Solid Modeling Aerospace Research Tool (SMART) user's guide, version 2.0
Mcmillin, Mark L.; Spangler, Jan L.; Dahmen, Stephen M.; Rehder, John J.
1993-01-01
The Solid Modeling Aerospace Research Tool (SMART) software package is used in the conceptual design of aerospace vehicles. It provides a highly interactive and dynamic capability for generating geometries with Bezier cubic patches. Features include automatic generation of commonly used aerospace constructs (e.g., wings and multilobed tanks); cross-section skinning; wireframe and shaded presentation; area, volume, inertia, and center-of-gravity calculations; and interfaces to various aerodynamic and structural analysis programs. A comprehensive description of SMART and how to use it is provided.
Occupant modeling in the aerospace environment
Yaklin, P.; Lim, T.; Marshall, R.
1999-01-01
Dynamic testing and occupant protection standards are a reality in the aerospace industry. Methods to model these situations are evolving. A method of modeling an occupant on a crew seat, in a drop test is presented. This method combines a rigid body occupant model with a finite element model of the
Common Cause Failure Modeling: Aerospace Versus Nuclear
Stott, James E.; Britton, Paul; Ring, Robert W.; Hark, Frank; Hatfield, G. Spencer
2010-01-01
Aggregate nuclear plant failure data is used to produce generic common-cause factors that are specifically for use in the common-cause failure models of NUREG/CR-5485. Furthermore, the models presented in NUREG/CR-5485 are specifically designed to incorporate two significantly distinct assumptions about the methods of surveillance testing from whence this aggregate failure data came. What are the implications of using these NUREG generic factors to model the common-cause failures of aerospace systems? Herein, the implications of using the NUREG generic factors in the modeling of aerospace systems are investigated in detail and strong recommendations for modeling the common-cause failures of aerospace systems are given.
Nonlinear modeling of an aerospace object dynamics
Davydov, I. E.; Davydov, E. I.
2017-01-01
Here are presented the scientific results, obtained by motion modeling of complicated technical systems of aerospace equipment with consideration of nonlinearities. Computerized panel that allows to measure mutual influence of the system's motion and stabilization device with consideration of its real characteristics has been developed. Analysis of motion stability of a system in general has been carried out and time relationships of the system's motion taking in account nonlinearities are presented.
A Model Aerospace Curriculum: August Martin High School.
Strickler, Mervin K., Jr.
This document presents an operational model of a thematic aerospace education school--the August Martin High School (New York). Part 1 briefly describes the nature of aviation/aerospace education and the background of the school. This background information includes how the school was formed, rationale for an aerospace thematic school, research…
Aerospace and maritime applications for solid oxide regenerative fuel cells
Sridhar, K.R.; McElroy, J. [Ion America Corporation, Sunnyvale, CA (United States)
2005-07-01
Solid Oxide Regenerative Fuel Cells (SORFC's) have been demonstrated for over 1000 hours of operation at degradation rates as low as 0.5% per 1000 hours for current densities as high as 300mA/cm2. Efficiency levels (fuel cell power out vs. electrolysis power in) have been demonstrated as high as 70% at 300mA/cm2. These attributes now make the SORFC a leading candidate for many applications not previously considered viable for the regenerative fuel cell approach. The SORFC has several distinct advantages in comparison with the familiar PEM regenerative fuel cell. Among the advantages are; oxidant electrode reversibility, water independence with open oxidant chambers, ability to operate at very low oxidant pressures, near unity current efficiency, and ability to electrolyze carbon dioxide as well as water. Additionally, a single SORFC stack can accomplish all of the above. With the aforementioned demonstrations and technical advantages various aerospace and maritime applications have become very attractive for the SORFC. At high altitude in the earth's atmosphere the SORFC can breathe the rare air with only a small performance penalty. In the space arena the SORFC can produce CO and oxygen from the Martian atmospheric carbon dioxide and alternately produce electricity from those reactant stores. In nuclear submarines the SORFC can produce pure oxygen by electrolysis of expired carbon dioxide and alternately produce electricity. In Unmanned Underwater Vehicles (UUVs) the SORFC can enable the desired range because of the very high energy density. (orig.)
Application of Smart Solid State Sensor Technology in Aerospace Applications
Hunter, Gary W.; Xu, Jennifer C.; Dungan, L.K.; Makel, D.; Ward, B.; Androjna, D.
2008-01-01
Aerospace applications require a range of chemical sensing technologies to monitor conditions in both space vehicles and aircraft operations. One example is the monitoring of oxygen. For example, monitoring of ambient oxygen (O2) levels is critical to ensuring the health, safety, and performance of humans living and working in space. Oxygen sensors can also be incorporated in detection systems to determine if hazardous leaks are occurring in space propulsion systems and storage facilities. In aeronautic applications, O2 detection has been investigated for fuel tank monitoring. However, as noted elsewhere, O2 is not the only species of interest in aerospace applications with a wide range of species of interest being relevant to understand an environmental or vehicle condition. These include combustion products such as CO, HF, HCN, and HCl, which are related to both the presence of a fire and monitoring of post-fire clean-up operations. This paper discusses the development of an electrochemical cell platform based on a polymer electrolyte, NAFION, and a three-electrode configuration. The approach has been to mature this basic platform for a range of applications and to test this system, combined with "Lick and Stick" electronics, for its viability to monitor an environment related to astronaut crew health and safety applications with an understanding that a broad range of applications can be addressed with a core technology.
Murray, R. W.
1973-01-01
A comprehensive study of advanced water recovery and solid waste processing techniques employed in both aerospace and domestic or commercial applications is reported. A systems approach was used to synthesize a prototype system design of an advanced water treatment/waste processing system. Household water use characteristics were studied and modified through the use of low water use devices and a limited amount of water reuse. This modified household system was then used as a baseline system for development of several water treatment waste processing systems employing advanced techniques. A hybrid of these systems was next developed and a preliminary design was generated to define system and hardware functions.
Elements of a collaborative systems model within the aerospace industry
Westphalen, Bailee R.
2000-10-01
Scope and method of study. The purpose of this study was to determine the components of current aerospace collaborative efforts. There were 44 participants from two selected groups surveyed for this study. Nineteen were from the Oklahoma Air National Guard based in Oklahoma City representing the aviation group. Twenty-five participants were from the NASA Johnson Space Center in Houston representing the aerospace group. The surveys for the aviation group were completed in reference to planning missions necessary to their operations. The surveys for the aerospace group were completed in reference to a well-defined and focused goal from a current mission. A questionnaire was developed to survey active participants of collaborative systems in order to consider various components found within the literature. Results were analyzed and aggregated through a database along with content analysis of open-ended question comments from respondents. Findings and conclusions. This study found and determined elements of a collaborative systems model in the aerospace industry. The elements were (1) purpose or mission for the group or team; (2) commitment or dedication to the challenge; (3) group or team meetings and discussions; (4) constraints of deadlines and budgets; (5) tools and resources for project and simulations; (6) significant contributors to the collaboration; (7) decision-making formats; (8) reviews of project; (9) participants education and employment longevity; (10) cross functionality of team or group members; (11) training on the job plus teambuilding; (12) other key elements identified relevant by the respondents but not included in the model such as communication and teamwork; (13) individual and group accountability; (14) conflict, learning, and performance; along with (15) intraorganizational coordination. These elements supported and allowed multiple individuals working together to solve a common problem or to develop innovation that could not have been
VARTM Process Modeling of Aerospace Composite Structures
Song, Xiao-Lan; Grimsley, Brian W.; Hubert, Pascal; Cano, Roberto J.; Loos, Alfred C.
2003-01-01
A three-dimensional model was developed to simulate the VARTM composite manufacturing process. The model considers the two important mechanisms that occur during the process: resin flow, and compaction and relaxation of the preform. The model was used to simulate infiltration of a carbon preform with an epoxy resin by the VARTM process. The model predicted flow patterns and preform thickness changes agreed qualitatively with the measured values. However, the predicted total infiltration times were much longer than measured most likely due to the inaccurate preform permeability values used in the simulation.
75 FR 12468 - Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes
2010-03-16
... With the next 10 Follow Quartz aileron pushrod bearings. hours time-in- Mountain Aerospace service (TIS... aileron Within 50 hours TIS Follow Quartz pushrod bearings. after the cleaning Mountain Aerospace and... Aerospace, Inc. Model 11E Airplanes AGENCY: Federal Aviation Administration (FAA), Department...
75 FR 39472 - Airworthiness Directives; Eclipse Aerospace, Inc. Model EA500 Airplanes
2010-07-09
... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Eclipse Aerospace... directive (AD) for certain Eclipse Aerospace, Inc. (Eclipse) Model EA500 airplanes. This proposed AD would... proposed AD, contact Eclipse Aerospace, Incorporated, 2503 Clark Carr Loop, SE., Albuquerque, New...
Computational Modeling of Flow Control Systems for Aerospace Vehicles Project
National Aeronautics and Space Administration — Clear Science Corp. proposes to develop computational methods for designing active flow control systems on aerospace vehicles with the primary objective of...
Solid model design simplification
Ames, A.L.; Rivera, J.J.; Webb, A.J.; Hensinger, D.M.
1997-12-01
This paper documents an investigation of approaches to improving the quality of Pro/Engineer-created solid model data for use by downstream applications. The investigation identified a number of sources of problems caused by deficiencies in Pro/Engineer`s geometric engine, and developed prototype software capable of detecting many of these problems and guiding users towards simplified, useable models. The prototype software was tested using Sandia production solid models, and provided significant leverage in attacking the simplification problem.
Aerothermoelastic modeling and simulation of aerospace vehicles using particle-based methods
Mason, Matthew Scott
As hypersonic aerospace vehicles are designed to increased performance specifications utilizing lighter weight, higher strength materials, fluid-structural interaction (FSI) effects become increasingly important to model, especially considering the increasing use of numerical models in many phases of design. When a fluid flows over a solid, a force is imparted on the solid and the solid deforms. This deformation, in turn, causes a change in the fluid flow field which modifies the force distribution on the structure. This FSI induced deformation is a primary area of study within the field of aeroelasticity. To further complicate the matter, thermodynamic and chemical effects are vitally important to model in the hypersonic flow regime. Traditionally, two separate numerical models are utilized to model the fluid and solid phases and a coupling algorithm accomplishes the task of modeling FSI. Coupling between the two solvers introduces numerical inaccuracies, inefficiencies, and for many mesh-based solvers, large deformations cannot be modeled. For this research, a combined Eulerian grid-based and Lagrangian particle-based solver known as the Material Point Method (MPM) is introduced and defined from prior research by others, and the particular MPM numerical code utilized in this research is outlined. The code combines the two separate solvers into a single numerical algorithm with separate constitutive relations for the fluid and solid phase, thereby allowing FSI modeling within a single computational framework. A limiter is applied to reduce numerical noise and oscillations around shock and expansion waves and exhibits a large reduction in oscillation amplitude and frequency. A Fourier's Law of Conduction heat transfer algorithm is implemented for heat transfer at a fluid-structure interface. The results from this heat transfer algorithm are compared with an independently developed numerical code for the single ramp case and experimental data for the double cone
A Conceptual Aerospace Vehicle Structural System Modeling, Analysis and Design Process
Mukhopadhyay, Vivek
2007-01-01
A process for aerospace structural concept analysis and design is presented, with examples of a blended-wing-body fuselage, a multi-bubble fuselage concept, a notional crew exploration vehicle, and a high altitude long endurance aircraft. Aerospace vehicle structures must withstand all anticipated mission loads, yet must be designed to have optimal structural weight with the required safety margins. For a viable systems study of advanced concepts, these conflicting requirements must be imposed and analyzed early in the conceptual design cycle, preferably with a high degree of fidelity. In this design process, integrated multidisciplinary analysis tools are used in a collaborative engineering environment. First, parametric solid and surface models including the internal structural layout are developed for detailed finite element analyses. Multiple design scenarios are generated for analyzing several structural configurations and material alternatives. The structural stress, deflection, strain, and margins of safety distributions are visualized and the design is improved. Over several design cycles, the refined vehicle parts and assembly models are generated. The accumulated design data is used for the structural mass comparison and concept ranking. The present application focus on the blended-wing-body vehicle structure and advanced composite material are also discussed.
Sampson, Enrique, Jr.
Many aerospace workers believe transferring work projects abroad has an erosive effect on the U.S. aerospace industry (Pritchard, 2002). This qualitative phenomenological study examines factors for outsourcing decisions and the perceived effects of outsourcing on U.S. aerospace workers. The research sample consists of aerospace industry leaders and nonleaders from the East Coast, Midwest, and West Coast of the United States. Moustakas' modified van Kaam methods of analysis (1994) and Decision Explorer analysis software were applied to the interview transcripts. Resultant data identified five core themes: communication, best value, opportunities, cost, and offset consideration. The themes provided the framework for a model designed to assist leaders in making effective decisions and communicating the benefits of those decisions when considering outsourcing of work projects.
Hilburn, Monty D.
Successful lean manufacturing and cellular manufacturing execution relies upon a foundation of leadership commitment and strategic planning built upon solid data and robust analysis. The problem for this study was to create and employ a simple lean transformation planning model and review process that could be used to identify functional support staff resources required to plan and execute lean manufacturing cells within aerospace assembly and manufacturing sites. The lean planning model was developed using available literature for lean manufacturing kaizen best practices and validated through a Delphi panel of lean experts. The resulting model and a standardized review process were used to assess the state of lean transformation planning at five sites of an international aerospace manufacturing and assembly company. The results of the three day, on-site review were compared with baseline plans collected from each of the five sites to determine if there analyzed, with focus on three critical areas of lean planning: the number and type of manufacturing cells identified, the number, type, and duration of planned lean and continuous kaizen events, and the quantity and type of functional staffing resources planned to support the kaizen schedule. Summarized data of the baseline and on-site reviews was analyzed with descriptive statistics. ANOVAs and paired-t tests at 95% significance level were conducted on the means of data sets to determine if null hypotheses related to cell, kaizen event, and support resources could be rejected. The results of the research found significant differences between lean transformation plans developed by site leadership and plans developed utilizing the structured, on-site review process and lean transformation planning model. The null hypothesis that there was no difference between the means of pre-review and on-site cell counts was rejected, as was the null hypothesis that there was no significant difference in kaizen event plans. These
Development of Parametric Mass and Volume Models for an Aerospace SOFC/Gas Turbine Hybrid System
Tornabene, Robert; Wang, Xiao-yen; Steffen, Christopher J., Jr.; Freeh, Joshua E.
2005-01-01
In aerospace power systems, mass and volume are key considerations to produce a viable design. The utilization of fuel cells is being studied for a commercial aircraft electrical power unit. Based on preliminary analyses, a SOFC/gas turbine system may be a potential solution. This paper describes the parametric mass and volume models that are used to assess an aerospace hybrid system design. The design tool utilizes input from the thermodynamic system model and produces component sizing, performance, and mass estimates. The software is designed such that the thermodynamic model is linked to the mass and volume model to provide immediate feedback during the design process. It allows for automating an optimization process that accounts for mass and volume in its figure of merit. Each component in the system is modeled with a combination of theoretical and empirical approaches. A description of the assumptions and design analyses is presented.
Murray, R. W.
1973-01-01
Water and sewage treatment systems are presented with concentration on the filtration of water. Equipment is described for organic removal, solids removal, nutrient removal, inorganic removal, and disinfection of the water. Such things as aseline hardware, additional piping connections, waste disposal, and costs involved are also reported.
Multiscale Modeling, Simulation and Visualization and Their Potential for Future Aerospace Systems
Noor, Ahmed K. (Compiler)
2002-01-01
This document contains the proceedings of the Training Workshop on Multiscale Modeling, Simulation and Visualization and Their Potential for Future Aerospace Systems held at NASA Langley Research Center, Hampton, Virginia, March 5 - 6, 2002. The workshop was jointly sponsored by Old Dominion University's Center for Advanced Engineering Environments and NASA. Workshop attendees were from NASA, other government agencies, industry, and universities. The objectives of the workshop were to give overviews of the diverse activities in hierarchical approach to material modeling from continuum to atomistics; applications of multiscale modeling to advanced and improved material synthesis; defects, dislocations, and material deformation; fracture and friction; thin-film growth; characterization at nano and micro scales; and, verification and validation of numerical simulations, and to identify their potential for future aerospace systems.
Shortis, Mark R.; Robson, Stuart; Jones, Thomas W.; Goad, William K.; Lunsford, Charles B.
2016-06-01
Aerospace engineers require measurements of the shape of aerodynamic surfaces and the six degree of freedom (6DoF) position and orientation of aerospace models to analyse structural dynamics and aerodynamic forces. The measurement technique must be non-contact, accurate, reliable, have a high sample rate and preferably be non-intrusive. Close range photogrammetry based on multiple, synchronised, commercial-off-the-shelf digital cameras can supply surface shape and 6DoF data at 5-15Hz with customisable accuracies. This paper describes data acquisition systems designed and implemented at NASA Langley Research Center to capture surface shapes and 6DoF data. System calibration and data processing techniques are discussed. Examples of experiments and data outputs are described.
Solid Oxide Fuel Cell/Gas Turbine Hybrid Cycle Technology for Auxiliary Aerospace Power
Steffen, Christopher J., Jr.; Freeh, Joshua E.; Larosiliere, Louis M.
2005-01-01
A notional 440 kW auxiliary power unit has been developed for 300 passenger commercial transport aircraft in 2015AD. A hybrid engine using solid-oxide fuel cell stacks and a gas turbine bottoming cycle has been considered. Steady-state performance analysis during cruise operation has been presented. Trades between performance efficiency and system mass were conducted with system specific energy as the discriminator. Fuel cell performance was examined with an area specific resistance. The ratio of fuel cell versus turbine power was explored through variable fuel utilization. Area specific resistance, fuel utilization, and mission length had interacting effects upon system specific energy. During cruise operation, the simple cycle fuel cell/gas turbine hybrid was not able to outperform current turbine-driven generators for system specific energy, despite a significant improvement in system efficiency. This was due in part to the increased mass of the hybrid engine, and the increased water flow required for on-board fuel reformation. Two planar, anode-supported cell design concepts were considered. Designs that seek to minimize the metallic interconnect layer mass were seen to have a large effect upon the system mass estimates.
Dynamic modeling of brushless dc motors for aerospace actuation
Demerdash, N. A.; Nehl, T. W.
1980-11-01
A discrete time model for simulation of the dynamics of samarium cobalt-type permanent magnet brushless dc machines is presented. The simulation model includes modeling of the interaction between these machines and their attached power conditioners. These are transistorized conditioner units. This model is part of an overall discrete-time analysis of the dynamic performance of electromechanical actuators, which was conducted as part of prototype development of such actuators studied and built for NASA-Johnson Space Center as a prospective alternative to hydraulic actuators presently used in shuttle orbiter applications. The resulting numerical simulations of the various machine and power conditioner current and voltage waveforms gave excellent correlation to the actual waveforms collected from actual hardware experimental testing. These results, numerical and experimental, are presented here for machine motoring, regeneration and dynamic braking modes. Application of the resulting model to the determination of machine current and torque profiles during closed-loop actuator operation were also analyzed and the results are given here. These results are given in light of an overall view of the actuator system components. The applicability of this method of analysis to design optimization and trouble-shooting in such prototype development is also discussed in light of the results at hand.
Dynamic modeling of brushless dc motors for aerospace actuation
Demerdash, N. A.; Nehl, T. W.
1980-01-01
A discrete time model for simulation of the dynamics of samarium cobalt-type permanent magnet brushless dc machines is presented. The simulation model includes modeling of the interaction between these machines and their attached power conditioners. These are transistorized conditioner units. This model is part of an overall discrete-time analysis of the dynamic performance of electromechanical actuators, which was conducted as part of prototype development of such actuators studied and built for NASA-Johnson Space Center as a prospective alternative to hydraulic actuators presently used in shuttle orbiter applications. The resulting numerical simulations of the various machine and power conditioner current and voltage waveforms gave excellent correlation to the actual waveforms collected from actual hardware experimental testing. These results, numerical and experimental, are presented here for machine motoring, regeneration and dynamic braking modes. Application of the resulting model to the determination of machine current and torque profiles during closed-loop actuator operation were also analyzed and the results are given here. These results are given in light of an overall view of the actuator system components. The applicability of this method of analysis to design optimization and trouble-shooting in such prototype development is also discussed in light of the results at hand.
Modeling of Unilateral Contact Conditions in Aerospace Systems
2005-12-31
1976. [21] C. Canudas de Wit, H. Olsson, K.J. Astrom , and P. Lischinsky. A new model for control of systems with friction. IEEE Transactions on...Vol. 30, No. 7, pp. 1083-1138. April, pp. 675-686. Canudas de Wit, C., Olsson, H., Astrom , K.J., and Valanis, K.C., 1971, "A Theory of...C., H. Olsson, K.J. Astrom , and P. Lischinsky, "A New Model for Control of Systems with Friction," IEEE Transactions on Automantic Control, vol. 40
Global Modeling of CO2 Discharges with Aerospace Applications
Chloe Berenguer
2014-01-01
Full Text Available We developed a global model aiming to study discharges in CO2 under various conditions, pertaining to a large spectrum of pressure, absorbed energy, and feeding values. Various physical conditions and form factors have been investigated. The model was applied to a case of radiofrequency discharge and to helicon type devices functioning in low and high feed conditions. In general, main charged species were found to be CO2+ for sufficiently low pressure cases and O− for higher pressure ones, followed by CO2+, CO+, and O2+ in the latter case. Dominant reaction is dissociation of CO2 resulting into CO production. Electronegativity, important for radiofrequency discharges, increases with pressure, arriving up to 3 for high flow rates for absorbed power of 250 W, and diminishes with increasing absorbed power. Model results pertaining to radiofrequency type plasma discharges are found in satisfactory agreement with those available from an existing experiment. Application to low and high flow rates feedings cases of helicon thruster allowed for evaluation of thruster functioning conditions pertaining to absorbed powers from 50 W to 1.8 kW. The model allows for a detailed evaluation of the CO2 potential to be used as propellant in electric propulsion devices.
Full-Range Mathematical Modeling of Turboshaft Engine in Aerospace
Sheng, Hanlin; Zhang, Tianhong; Jiang, Wei
2016-12-01
In this paper, an approximate computation method of low-speed component characteristics in aeroengine is used and full-range component characteristics is obtained by combining experimental data above idle. Moreover, based on components matching method and variable specific heat method, a full-range static and dynamic mathematical model of turboshaft engine is built, including start-up state. And the numerical simulation result of the engine whole working process is also showed in this paper. The comparison result between the simulation result and the experimental data shows that, the full-range model built by the computation method of low-speed component characteristics is of a certain accuracy, which can meet the needs of a turboshaft engine semi-physical simulation.
Influence of Stochastic Modelling in Aerospace in EMC Environment
Patier, Laurent; Lallechere, Sebastien; Bonnet, Pierre; Paladian, Francoise
2016-05-01
This paper aims to demonstrate the ability of stochastic collocation method (SCM) for electromagnetic compatibility (EMC) space applications. The increasing number of antennas embedded on spacecraft implies growth of potential EMC issues. Harsh constraints on antennas could spoil ideal radiating performances. Project management for spacecraft development requires deeper analyses (e.g., modifying locations of several radiators) between qualification and flight models. We propose here to quantify behaviour modifications using SCM in antennas and EMC frameworks.
Atmospheric Turbulence Modeling for Aerospace Vehicles: Fractional Order Fit
Kopasakis, George (Inventor)
2015-01-01
An improved model for simulating atmospheric disturbances is disclosed. A scale Kolmogorov spectral may be scaled to convert the Kolmogorov spectral into a finite energy von Karman spectral and a fractional order pole-zero transfer function (TF) may be derived from the von Karman spectral. Fractional order atmospheric turbulence may be approximated with an integer order pole-zero TF fit, and the approximation may be stored in memory.
Aerospace laser sensing of cloudiness: numerical statistical modeling
Kargin, A. B.; Kargin, B. A.; Lavrov, M. V.
2013-08-01
In the numerical modeling of laser radiation transfer in optically dense cloudy media it is necessary to take into account multiple scattering effects, which alter the spatiotemporal structure of light pulses. The Monte Carlo method makes it possible to achieve the most complete account of these effects in the solution of direct problems of laser sensing of scattering media. This work considers two problems. The first is connected with construction of an adequate optical model of crystalline clouds which takes account their optical anisotropy. The second touches on questions of Monte Carlo modeling of laser radiation transfer in optically anisotropic media. A number of results of numerical experiments are presented which establish a quantitative connection between some cloud parameters and the magnitude and shape of the time convolution of a non-stationary laser return signal reflected by a single-layer continuous crystalline or liquid-droplet cloud and by two-level continuous cloudiness, when the crystalline cloud is located above the liquid-droplet cloud.
Michaud, Vince
2015-01-01
NASA Aerospace Medicine overview - Aerospace Medicine is that specialty area of medicine concerned with the determination and maintenance of the health, safety, and performance of those who fly in the air or in space.
Automated Modeling and Simulation Using the Bond Graph Method for the Aerospace Industry
Granda, Jose J.; Montgomery, Raymond C.
2003-01-01
Bond graph modeling was originally developed in the late 1950s by the late Prof. Henry M. Paynter of M.I.T. Prof. Paynter acted well before his time as the main advantage of his creation, other than the modeling insight that it provides and the ability of effectively dealing with Mechatronics, came into fruition only with the recent advent of modern computer technology and the tools derived as a result of it, including symbolic manipulation, MATLAB, and SIMULINK and the Computer Aided Modeling Program (CAMPG). Thus, only recently have these tools been available allowing one to fully utilize the advantages that the bond graph method has to offer. The purpose of this paper is to help fill the knowledge void concerning its use of bond graphs in the aerospace industry. The paper first presents simple examples to serve as a tutorial on bond graphs for those not familiar with the technique. The reader is given the basic understanding needed to appreciate the applications that follow. After that, several aerospace applications are developed such as modeling of an arresting system for aircraft carrier landings, suspension models used for landing gears and multibody dynamics. The paper presents also an update on NASA's progress in modeling the International Space Station (ISS) using bond graph techniques, and an advanced actuation system utilizing shape memory alloys. The later covers the Mechatronics advantages of the bond graph method, applications that simultaneously involves mechanical, hydraulic, thermal, and electrical subsystem modeling.
Modeling solid-state precipitation
Nebylov, AlexanderKozeschnik, Ernst
2012-01-01
Over recent decades, modeling and simulation of solid-state precipitation has attracted increased attention in academia and industry due to their important contributions in designing properties of advanced structural materials and in increasing productivity and decreasing costs for expensive alloying. In particular, precipitation of second phases is an important means for controlling the mechanical-technological properties of structural materials. However, profound physical modeling of precipitation is not a trivial task. This book introduces you to the classical methods of precipitation model
Mathematical modelling in solid mechanics
Sofonea, Mircea; Steigmann, David
2017-01-01
This book presents new research results in multidisciplinary fields of mathematical and numerical modelling in mechanics. The chapters treat the topics: mathematical modelling in solid, fluid and contact mechanics nonconvex variational analysis with emphasis to nonlinear solid and structural mechanics numerical modelling of problems with non-smooth constitutive laws, approximation of variational and hemivariational inequalities, numerical analysis of discrete schemes, numerical methods and the corresponding algorithms, applications to mechanical engineering numerical aspects of non-smooth mechanics, with emphasis on developing accurate and reliable computational tools mechanics of fibre-reinforced materials behaviour of elasto-plastic materials accounting for the microstructural defects definition of structural defects based on the differential geometry concepts or on the atomistic basis interaction between phase transformation and dislocations at nano-scale energetic arguments bifurcation and post-buckling a...
无
2007-01-01
Polarized magnetic system has a series of features, such as small volume, light weight, low power consumption, high sensitivity, quick movement and so on, widely used in the products of the military aerospace electromagnetic relay. The typical polarized magnetic system has mainly four structures and its simplified equivalent magnetic circuits model is the base of the design of the electromagnetic relay with permanent magnet. In the past, the analysis method that people used was difficult to build the unified mathematical models, which divided the work gap magnetic flux into "permanent magnet flux" and "electromagnetic flux". Based on the analysis method of the work gap magnetic voltage, this paper founds the unified mathematical model of the polarized magnetic system and divides the attractive torque into permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula. It analyses the influence of permanent magnet sizes on permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula and the conclusions can direct the design of aerospace electromagnetic relay with permanent magnet.
A simple analytical aerodynamic model of Langley Winged-Cone Aerospace Plane concept
Pamadi, Bandu N.
1994-01-01
A simple three DOF analytical aerodynamic model of the Langley Winged-Coned Aerospace Plane concept is presented in a form suitable for simulation, trajectory optimization, and guidance and control studies. The analytical model is especially suitable for methods based on variational calculus. Analytical expressions are presented for lift, drag, and pitching moment coefficients from subsonic to hypersonic Mach numbers and angles of attack up to +/- 20 deg. This analytical model has break points at Mach numbers of 1.0, 1.4, 4.0, and 6.0. Across these Mach number break points, the lift, drag, and pitching moment coefficients are made continuous but their derivatives are not. There are no break points in angle of attack. The effect of control surface deflection is not considered. The present analytical model compares well with the APAS calculations and wind tunnel test data for most angles of attack and Mach numbers.
NASA Perspective and Modeling of Thermal Runaway Propagation Mitigation in Aerospace Batteries
Shack, P.; Iannello, C.; Rickman, S.; Button, R.
2014-01-01
NASA has traditionally sought to reduce the likelihood of a single cell thermal runaway (TR) in their aerospace batteries to an absolute minimum by employing rigorous screening program of the cells. There was generally a belief that TR propagation resulting in catastrophic failure of the battery was a forgone conclusion for densely packed aerospace lithium-ion batteries. As it turns out, this may not be the case. An increasing number of purportedly TR propagation-resistant batteries are appearing among NASA partners in the commercial sector and the Department of Defense. In the recent update of the battery safety standard (JSC 20793) to address this paradigm shift, the NASA community included requirements for assessing TR severity and identifying simple, low-cost severity reduction measures. Unfortunately, there are no best-practice guidelines for this work in the Agency, so the first project team attempting to meet these requirements would have an undue burden placed upon them. A NASA engineering Safety Center (NESC) team set out to perform pathfinding activities for meeting those requirements. This presentation will provide contextual background to this effort, as well as initial results in attempting to model and simulate TR heat transfer and propagation within battery designs.
Aerospace Technology (Aerospace Engineering Degree)
Tiseira Izaguirre, Andrés Omar; Blanco Rodríguez, David; Carreres Talens, Marcos; Fajardo Peña, Pablo
2013-01-01
Apuntes de la asignatura Tecnología Aeroespacial Tiseira Izaguirre, AO.; Blanco Rodríguez, D.; Carreres Talens, M.; Fajardo Peña, P. (2013). Aerospace Technology (Aerospace Engineering Degree). Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/35263.
Chambers, Joseph
2010-01-01
The state of the art in aeronautical engineering has been continually accelerated by the development of advanced analysis and design tools. Used in the early design stages for aircraft and spacecraft, these methods have provided a fundamental understanding of physical phenomena and enabled designers to predict and analyze critical characteristics of new vehicles, including the capability to control or modify unsatisfactory behavior. For example, the relatively recent emergence and routine use of extremely powerful digital computer hardware and software has had a major impact on design capabilities and procedures. Sophisticated new airflow measurement and visualization systems permit the analyst to conduct micro- and macro-studies of properties within flow fields on and off the surfaces of models in advanced wind tunnels. Trade studies of the most efficient geometrical shapes for aircraft can be conducted with blazing speed within a broad scope of integrated technical disciplines, and the use of sophisticated piloted simulators in the vehicle development process permits the most important segment of operations the human pilot to make early assessments of the acceptability of the vehicle for its intended mission. Knowledgeable applications of these tools of the trade dramatically reduce risk and redesign, and increase the marketability and safety of new aerospace vehicles. Arguably, one of the more viable and valuable design tools since the advent of flight has been testing of subscale models. As used herein, the term "model" refers to a physical article used in experimental analyses of a larger full-scale vehicle. The reader is probably aware that many other forms of mathematical and computer-based models are also used in aerospace design; however, such topics are beyond the intended scope of this document. Model aircraft have always been a source of fascination, inspiration, and recreation for humans since the earliest days of flight. Within the scientific
Modeling solid-state precipitation
Nebylov, AlexanderKozeschnik, Ernst
2012-01-01
Over recent decades, modeling and simulation of solid-state precipitation has attracted increased attention in academia and industry due to their important contributions in designing properties of advanced structural materials and in increasing productivity and decreasing costs for expensive alloying. In particular, precipitation of second phases is an important means for controlling the mechanical-technological properties of structural materials. However, profound physical modeling of precipitation is not a trivial task. This book introduces you to the classical methods of precipitation modeling and to recently-developed advanced, computationally-efficient techniques. If you're a research professional, academic, or student, you'll learn: nucleation theory, precipitate growth, calculation of interfacial energies. advanced techniques for technologically relevant multicomponent systems and complex thermo-mechanical treatments. numerical approaches using evolution equations and discrete particle size distribu...
75 FR 61345 - Airworthiness Directives; Eclipse Aerospace, Inc. Model EA500 Airplanes
2010-10-05
... 2010-CE-027-AD; Amendment 39-16459; AD 2010-20-24] RIN 2120-AA64 Airworthiness Directives; Eclipse... identified in this AD, contact Eclipse Aerospace Incorporated, 2503 Clark Carr Loop, SE., Albuquerque, New... Information Bulletin (SAIB) Chris Jackman, Eclipse Aerospace Incorporated, proposed the withdrawal of the...
2011-03-10
...-005-AD; Amendment 39-16631; AD 2011-06-06] RIN 2120-AA64 Airworthiness Directives; Eclipse Aerospace..., we issued AD 2008-24-07, amendment 39-15747 (73 FR 70866, November 24, 2008), for certain Eclipse Aviation Corporation (Eclipse) Model EA500 airplanes equipped with a Pratt and Whitney Canada, Corp....
Reed, H; Leckey, Cara A C; Dick, A; Harvey, G; Dobson, J
2017-09-05
Ultrasonic damage detection and characterization is commonly used in nondestructive evaluation (NDE) of aerospace composite components. In recent years there has been an increased development of guided wave based methods. In real materials and structures, these dispersive waves result in complicated behavior in the presence of complex damage scenarios. Model-based characterization methods utilize accurate three dimensional finite element models (FEMs) of guided wave interaction with realistic damage scenarios to aid in defect identification and classification. This work describes an inverse solution for realistic composite damage characterization by comparing the wavenumber-frequency spectra of experimental and simulated ultrasonic inspections. The composite laminate material properties are first verified through a Bayesian solution (Markov chain Monte Carlo), enabling uncertainty quantification surrounding the characterization. A study is undertaken to assess the efficacy of the proposed damage model and comparative metrics between the experimental and simulated output. The FEM is then parameterized with a damage model capable of describing the typical complex damage created by impact events in composites. The damage is characterized through a transdimensional Markov chain Monte Carlo solution, enabling a flexible damage model capable of adapting to the complex damage geometry investigated here. The posterior probability distributions of the individual delamination petals as well as the overall envelope of the damage site are determined. Copyright © 2017 Elsevier B.V. All rights reserved.
A Model-Based Approach to Engineering Behavior of Complex Aerospace Systems
Ingham, Michel; Day, John; Donahue, Kenneth; Kadesch, Alex; Kennedy, Andrew; Khan, Mohammed Omair; Post, Ethan; Standley, Shaun
2012-01-01
One of the most challenging yet poorly defined aspects of engineering a complex aerospace system is behavior engineering, including definition, specification, design, implementation, and verification and validation of the system's behaviors. This is especially true for behaviors of highly autonomous and intelligent systems. Behavior engineering is more of an art than a science. As a process it is generally ad-hoc, poorly specified, and inconsistently applied from one project to the next. It uses largely informal representations, and results in system behavior being documented in a wide variety of disparate documents. To address this problem, JPL has undertaken a pilot project to apply its institutional capabilities in Model-Based Systems Engineering to the challenge of specifying complex spacecraft system behavior. This paper describes the results of the work in progress on this project. In particular, we discuss our approach to modeling spacecraft behavior including 1) requirements and design flowdown from system-level to subsystem-level, 2) patterns for behavior decomposition, 3) allocation of behaviors to physical elements in the system, and 4) patterns for capturing V&V activities associated with behavioral requirements. We provide examples of interesting behavior specification patterns, and discuss findings from the pilot project.
a computational modeling for image motion velocity on focal plane of aerial & aerospace frame camera
Zhang, X.; Jin, G.; Li, Z. Y.
As the resolving power and geometric accuracy of aerial aerospace imaging is demanded to be higher the researches in technology of IMC become very important In order to compensate the image motion on focal plane the rule of FPIMV Focal Plane Image Motion Velocity should be grasped while the posture of aircraft and the modes of imaging are under changing In this paper a reasonable computational modeling scheme to the problem is introduced Coordinates transformation method is utilized for calculation of forward FPIMV under different condition of vertical and sloped imaging meanwhile integrated with three axes posture and angle velocity of aircraft Forward FPIMV combine with pitch roll and yaw FPIMV is considered simultaneously and the derivation calculating expressions of frame camera FPIMV under different conditions is presented in detail The solution is applied to computational simulation and has been confirmed to be effective based on the calculation result and it lays the foundation for our farther researches on frame camera IMC technology Key words IMC FPIMV Focal Plane Image Motion Velocity Coordinates transformation method
Building Mathematical Models Of Solid Objects
Randall, Donald P.; Jones, Kennie H.; Von Ofenheim, William H.; Gates, Raymond L.; Matthews, Christine G.
1989-01-01
Solid Modeling Program (SMP) version 2.0 provides capability to model complex solid objects mathematically through aggregation of geometric primitives (parts). System provides designer with basic set of primitive parts and capability to define new primitives. Six primitives included in present version: boxes, cones, spheres, paraboloids, tori, and trusses. Written in VAX/VMS FORTRAN 77.
2011-10-14
...These special conditions are issued for the Gulfstream Aerospace LP (GALP) model G280 airplane. This airplane will have a novel or unusual design feature associated with engine torque loads imposed by sudden engine stoppage. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
Udlock, D. E.
1978-01-01
Storage of solid propellants in either a dry or a vacuum environment causes a significantly greater increase in the propellants' modulus and maximum tensile strength than does ambient storage. It is postulated that these physical property changes can be attributed to the effect trace amount of moisture has on the bond between the propellants' binder and oxidizer.
Molecular Modeling of Solid Fluid Phase Behavior
Peter A. Monson
2007-12-20
This report gives a summary of the achievements under DOE contract No. DOE/ER/14150 during the period September 1, 1990 to December 31, 2007. This project was concerned with the molecular modeling of solid-fluid equilibrium. The focus was on understanding how solid-fluid and solid-solid phase behavior are related to molecular structure, and the research program made a seminal contribution in this area. The project led to 34 journal articles, including a comprehensive review article published in Advances in Chemical Physics. The DOE funding supported the work of 5 Ph.D. students, 2 M.S. students and 5 postdoctoral researchers.
2013-02-13
... engine, four- passenger, composite airplane. The installation of winglets, as proposed by Tamarack... Aerospace Group's modification. The design change will install winglets and an Active Technology Load Alleviation System (ATLAS). The addition of the ATLAS mitigates the negative effects of the winglets...
Sandeep Arora
2017-01-01
Full Text Available Evolutionarily, man is a terrestrial mammal, adapted to land. Aviation and now space/microgravity environment, hence, pose new challenges to our physiology. Exposure to these changes affects the human body in acute and chronic settings. Since skin reflects our mental and physical well-being, any change/side effects of this environment shall be detected on the skin. Aerospace industry offers a unique environment with a blend of all possible occupational disorders, encompassing all systems of the body, particularly the skin. Aerospace dermatologists in the near future shall be called upon for their expertise as we continue to push human physiological boundaries with faster and more powerful military aircraft and look to colonize space stations and other planets. Microgravity living shall push dermatology into its next big leap-space, the final frontier. This article discusses the physiological effects of this environment on skin, effect of common dermatoses in aerospace environment, effect of microgravity on skin, and occupational hazards of this industry.
Arora, Gp Capt Sandeep
2017-01-01
Evolutionarily, man is a terrestrial mammal, adapted to land. Aviation and now space/microgravity environment, hence, pose new challenges to our physiology. Exposure to these changes affects the human body in acute and chronic settings. Since skin reflects our mental and physical well-being, any change/side effects of this environment shall be detected on the skin. Aerospace industry offers a unique environment with a blend of all possible occupational disorders, encompassing all systems of the body, particularly the skin. Aerospace dermatologists in the near future shall be called upon for their expertise as we continue to push human physiological boundaries with faster and more powerful military aircraft and look to colonize space stations and other planets. Microgravity living shall push dermatology into its next big leap-space, the final frontier. This article discusses the physiological effects of this environment on skin, effect of common dermatoses in aerospace environment, effect of microgravity on skin, and occupational hazards of this industry.
Cellular Automata Model for Elastic Solid Material
DONG Yin-Feng; ZHANG Guang-Cai; XU Ai-Guo; GAN Yan-Biao
2013-01-01
The Cellular Automaton (CA) modeling and simulation of solid dynamics is a long-standing difficult problem.In this paper we present a new two-dimensional CA model for solid dynamics.In this model the solid body is represented by a set of white and black particles alternatively positioned in the x-and y-directions.The force acting on each particle is represented by the linear summation of relative displacements of the nearest-neighboring particles.The key technique in this new model is the construction of eight coefficient matrices.Theoretical and numerical analyses show that the present model can be mathematically described by a conservative system.So,it works for elastic material.In the continuum limit the CA model recovers the well-known Navier equation.The coefficient matrices are related to the shear module and Poisson ratio of the material body.Compared with previous CA model for solid body,this model realizes the natural coupling of deformations in the x-and y-directions.Consequently,the wave phenomena related to the Poisson ratio effects are successfully recovered.This work advances significantly the CA modeling and simulation in the field of computational solid dynamics.
Modelling end-pumped solid state lasers
Bernhardi, E.H.; Bollig, C.; Forbes, A.; Esser, M.J.D.; Wörhoff, K.; Agazzi, L.; Ismail, N.; Leijtens, X.
2008-01-01
The operation dynamics of end-pumped solid-state lasers are investigated by means of a spatially resolved numerical rate-equation model and a time-dependent analytical thermal model. The rate-equation model allows the optimization of parameters such as the output coupler transmission and gain medium
Comfort, A.
1982-01-01
The relevancy of gerontology and geriatrics to the discipline of aerospace medicine is examined. It is noted that since the shuttle program gives the facility to fly passengers, including specially qualified older persons, it is essential to examine response to acceleration, weightlessness, and re-entry over the whole adult lifespan, not only its second quartile. The physiological responses of the older person to weightlessness and the return to Earth gravity are reviewed. The importance of the use of the weightless environment to solve critical problems in the fields of fundamental gerontology and geriatrics is also stressed.
2011-10-14
...These special conditions are issued for the Gulfstream Aerospace LP (GALP) Model G280 airplane. This airplane will have a novel or unusual design feature associated with the pilot-compartment view through a hydrophobic windshield coating, in lieu of windshield wipers. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
CFD modelling of solid propellant ignition
Lowe, C
1996-01-01
Solid propellant is the highly energetic fuel burnt in the combustion chamber of ballistic weapons. It is manufactured, for this purpose, in either granular or stick form. Internal ballistics describes the behavior within the combustion chamber throughout the ballistic cycle upto projectile exit from the muzzle of the gun barrel. Over the last twenty years this has been achieved by modelling the process using two-phase flow equations. The solid granules or sticks constitute ...
Aerospace Systems Monitor Project
National Aeronautics and Space Administration — Proposal Title: Aerospace Systems Monitor PHASE 1 Technical Abstract: This Phase II STTR project will continue development and commercialization of the Aerospace...
Combustion response modeling for composite solid propellants
1977-01-01
A computerized mathematical model of the combustion response function of composite solid propellants was developed with particular attention to the contributions of the solid phase heterogeneity. The one-dimensional model treats the solid phase as alternating layers of ammonium perchlorate and binder, with an exothermic melt layer at the surface. Solution of the Fourier heat equation in the solid provides temperature and heat flux distributions with space and time. The problem is solved by conserving the heat flux at the surface from that produced by a suitable model of the gas phase. An approximation of the BDP flame model is utilized to represent the gas phase. By the use of several reasonable assumptions, it is found that a significant portion of the problem can be solved in closed form. A method is presented by which the model can be applied to tetramodal particle size distributions. A computerized steady-state version of the model was completed, which served to validate the various approximations and lay a foundation for the combustion response modeling. The combustion response modeling was completed in a form which does not require an iterative solution, and some preliminary results were acquired.
Haptics-based dynamic implicit solid modeling.
Hua, Jing; Qin, Hong
2004-01-01
This paper systematically presents a novel, interactive solid modeling framework, Haptics-based Dynamic Implicit Solid Modeling, which is founded upon volumetric implicit functions and powerful physics-based modeling. In particular, we augment our modeling framework with a haptic mechanism in order to take advantage of additional realism associated with a 3D haptic interface. Our dynamic implicit solids are semi-algebraic sets of volumetric implicit functions and are governed by the principles of dynamics, hence responding to sculpting forces in a natural and predictable manner. In order to directly manipulate existing volumetric data sets as well as point clouds, we develop a hierarchical fitting algorithm to reconstruct and represent discrete data sets using our continuous implicit functions, which permit users to further design and edit those existing 3D models in real-time using a large variety of haptic and geometric toolkits, and visualize their interactive deformation at arbitrary resolution. The additional geometric and physical constraints afford more sophisticated control of the dynamic implicit solids. The versatility of our dynamic implicit modeling enables the user to easily modify both the geometry and the topology of modeled objects, while the inherent physical properties can offer an intuitive haptic interface for direct manipulation with force feedback.
Flower solid modeling based on sketches
Zhan DING; Shu-chang XU; Xiu-zi YE; Yin ZHANG; San-yuan ZHANG
2008-01-01
In this paper we propose a method to model flowers of solid shape. Based on (Ijiri et al., 2005)'s method, we separate individual flower modeling and inflorescence modeling procedures into structure and geometry modeling. We incorporate interactive editing gestures to allow the user to edit structure parameters freely onto structure diagram. Furthermore, we use free-hand sketching techniques to allow users to create and edit 3D geometrical elements freely and easily. The final step is to automatically merge all independent 3D geometrical elements into a single waterproof mesh. Our experiments show that this solid modeling approach is promising. Using our approach, novice users can create vivid flower models easily and freely. The generated flower model is waterproof. It can have applications in visualization, animation, gaming, and toys and decorations if printed out on 3D rapid prototyping devices.
Fundamental Physics and Model Assumptions in Turbulent Combustion Models for Aerospace Propulsion
2014-06-01
Astronautics also speculate that, for non-equilibrium flows, this effect could be even stronger. Combustion problems wherein the energy deposition often...flamelet regime. However, in the presence of slow reactions such as pyrolysis and/or at high Reynolds numbers that lead to smaller turbulent scales...376404. 20S. Menon and N. Patel. Subgrid Modeling for Simulation of Spray Combustion in Large-Scale Combustors. AIAA Journal, 44(4):709–723, 2006. 21M
Modeling the electrified solid-liquid interface
Rossmeisl, Jan; Skulason, Egill; Björketun, Mårten;
2008-01-01
A detailed atomistic model based on density functional theory calculations is presented of the charged solid-electrolyte interface. Having protons solvated in a water bilayer outside a Pt(111) slab with excess electrons, we show how the interface capacitance is well described and how the work...
Ephraim Suhir
2014-12-01
Full Text Available Improvements in safety in the air and in space can be achieved through better ergonomics, better work environment, and other efforts of the traditional avionic psychology that directly affect human behaviors and performance. There is also a significant potential, however, for further reduction in aerospace accidents and casualties through better understanding the role that various uncertainties play in the planner’s and operator’s worlds of work, when never-perfect human, never failure-free navigation equipment and instrumentation, never hundred-percent-predictable response of the object of control (air- or space-craft, and uncertain-and-often-harsh environments contribute jointly to the likelihood of a mishap. By employing quantifiable and measurable ways of assessing the role and significance of such uncertainties and treating a human-in-the-loop (HITL as a part, often the most crucial part, of a complex man–instrumentation–equipment–vehicle–environment system, one could improve dramatically the state-of-the-art in assuring aerospace operational safety. This can be done by predicting, quantifying and, if necessary, even specifying an adequate (low enough probability of a possible accident. Nothing and nobody is perfect, of course, and the difference between a highly reliable object, product, performance or a mission and an insufficiently reliable one is “merely” in the level of the never-zero probability of failure. Application of the probabilistic predictive modeling (PPM concept provides a natural and an effective means for reduction of vehicular casualties. When success and safety are imperative, ability to predict and quantify the outcome of an HITL related mission or a situation is a must. This is not the current practice though. The application of the PPM concept can improve therefore the state-of-the-art in understanding and accounting for the human performance in a vehicular mission or a situation. While the traditional
Dynamics of aerospace vehicles
Schmidt, David K.
1991-01-01
The focus of this research was to address the modeling, including model reduction, of flexible aerospace vehicles, with special emphasis on models used in dynamic analysis and/or guidance and control system design. In the modeling, it is critical that the key aspects of the system being modeled be captured in the model. In this work, therefore, aspects of the vehicle dynamics critical to control design were important. In this regard, fundamental contributions were made in the areas of stability robustness analysis techniques, model reduction techniques, and literal approximations for key dynamic characteristics of flexible vehicles. All these areas are related. In the development of a model, approximations are always involved, so control systems designed using these models must be robust against uncertainties in these models.
Sankararaman, Shankar; Goebel, Kai
2013-01-01
This paper investigates the use of the inverse first-order reliability method (inverse- FORM) to quantify the uncertainty in the remaining useful life (RUL) of aerospace components. The prediction of remaining useful life is an integral part of system health prognosis, and directly helps in online health monitoring and decision-making. However, the prediction of remaining useful life is affected by several sources of uncertainty, and therefore it is necessary to quantify the uncertainty in the remaining useful life prediction. While system parameter uncertainty and physical variability can be easily included in inverse-FORM, this paper extends the methodology to include: (1) future loading uncertainty, (2) process noise; and (3) uncertainty in the state estimate. The inverse-FORM method has been used in this paper to (1) quickly obtain probability bounds on the remaining useful life prediction; and (2) calculate the entire probability distribution of remaining useful life prediction, and the results are verified against Monte Carlo sampling. The proposed methodology is illustrated using a numerical example.
Solid mechanics theory, modeling, and problems
Bertram, Albrecht
2015-01-01
This textbook offers an introduction to modeling the mechanical behavior of solids within continuum mechanics and thermodynamics. To illustrate the fundamental principles, the book starts with an overview of the most important models in one dimension. Tensor calculus, which is called for in three-dimensional modeling, is concisely presented in the second part of the book. Once the reader is equipped with these essential mathematical tools, the third part of the book develops the foundations of continuum mechanics right from the beginning. Lastly, the book’s fourth part focuses on modeling the mechanics of materials and in particular elasticity, viscoelasticity and plasticity. Intended as an introductory textbook for students and for professionals interested in self-study, it also features numerous worked-out examples to aid in understanding.
Inference-based procedural modeling of solids
Biggers, Keith
2011-11-01
As virtual environments become larger and more complex, there is an increasing need for more automated construction algorithms to support the development process. We present an approach for modeling solids by combining prior examples with a simple sketch. Our algorithm uses an inference-based approach to incrementally fit patches together in a consistent fashion to define the boundary of an object. This algorithm samples and extracts surface patches from input models, and develops a Petri net structure that describes the relationship between patches along an imposed parameterization. Then, given a new parameterized line or curve, we use the Petri net to logically fit patches together in a manner consistent with the input model. This allows us to easily construct objects of varying sizes and configurations using arbitrary articulation, repetition, and interchanging of parts. The result of our process is a solid model representation of the constructed object that can be integrated into a simulation-based environment. © 2011 Elsevier Ltd. All rights reserved.
The Chameleon Solid Rocket Propulsion Model
Robertson, Glen A.
2010-01-01
The Khoury and Weltman (2004a and 2004b) Chameleon Model presents an addition to the gravitation force and was shown by the author (Robertson, 2009a and 2009b) to present a new means by which one can view other forces in the Universe. The Chameleon Model is basically a density-dependent model and while the idea is not new, this model is novel in that densities in the Universe to include the vacuum of space are viewed as scalar fields. Such an analogy gives the Chameleon scalar field, dark energy/dark matter like characteristics; fitting well within cosmological expansion theories. In respect to this forum, in this paper, it is shown how the Chameleon Model can be used to derive the thrust of a solid rocket motor. This presents a first step toward the development of new propulsion models using density variations verse mass ejection as the mechanism for thrust. Further, through the Chameleon Model connection, these new propulsion models can be tied to dark energy/dark matter toward new space propulsion systems utilizing the vacuum scalar field in a way understandable by engineers, the key toward the development of such systems. This paper provides corrections to the Chameleon rocket model in Robertson (2009b).
Demerdash, N. A. O.; Nehl, T. W.
1979-01-01
The development, fabrication and evaluation of a prototype electromechanical actuator (EMA) is discussed. Application of the EMA as a motor for control surfaces in aerospace flight is examined. A mathematical model of the EMA is developed for design optimization. Nonlinearities which complicate the mathematical model are discussed. The dynamics of the EMA from the underlying physical principles are determined and a discussion of similating the control logic by means of equivalent boolean expressions is presented.
Wax Precipitation Modeled with Many Mixed Solid Phases
Heidemann, Robert A.; Madsen, Jesper; Stenby, Erling Halfdan
2005-01-01
The behavior of the Coutinho UNIQUAC model for solid wax phases has been examined. The model can produce as many mixed solid phases as the number of waxy components. In binary mixtures, the solid rich in the lighter component contains little of the heavier component but the second phase shows sub...
Photogrammetric techniques for aerospace applications
Liu, Tianshu; Burner, Alpheus W.; Jones, Thomas W.; Barrows, Danny A.
2012-10-01
Photogrammetric techniques have been used for measuring the important physical quantities in both ground and flight testing including aeroelastic deformation, attitude, position, shape and dynamics of objects such as wind tunnel models, flight vehicles, rotating blades and large space structures. The distinct advantage of photogrammetric measurement is that it is a non-contact, global measurement technique. Although the general principles of photogrammetry are well known particularly in topographic and aerial survey, photogrammetric techniques require special adaptation for aerospace applications. This review provides a comprehensive and systematic summary of photogrammetric techniques for aerospace applications based on diverse sources. It is useful mainly for aerospace engineers who want to use photogrammetric techniques, but it also gives a general introduction for photogrammetrists and computer vision scientists to new applications.
76 FR 50881 - Airworthiness Directives; M7 Aerospace LP Airplanes
2011-08-17
...-025-AD; Amendment 39-16771; AD 2011-17-07] RIN 2120-AA64 Airworthiness Directives; M7 Aerospace LP.... SUMMARY: We are adopting a new airworthiness directive (AD) for certain M7 Aerospace LP Models SA226-T... AD, contact M7 Aerospace, LC, 10823 NE. Entrance Road, San Antonio, Texas 78216; telephone (210)...
78 FR 77618 - Airworthiness Directives; M7 Aerospace LLC Airplanes
2013-12-24
... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; M7 Aerospace LLC...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for all M7 Aerospace LLC Models SA226-AT... bulkhead. This proposed AD also requires reporting certain inspection results to M7 Aerospace LLC. We...
77 FR 54787 - Airworthiness Directives; M7 Aerospace LLC Airplanes
2012-09-06
...-17177; AD 2012-18-01] RIN 2120-AA64 Airworthiness Directives; M7 Aerospace LLC Airplanes AGENCY: Federal... new airworthiness directive (AD) for all M7 Aerospace LLC Models SA226-AT, SA226-T, SA226-T(B), SA226... information identified in this AD, contact M7 Aerospace LP, 10823 NE Entrance Road, San Antonio, Texas...
77 FR 75908 - Airworthiness Directives; Gulfstream Aerospace Corporation
2012-12-26
... Aerospace Corporation AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Aerospace Corporation Model GV and GV-SP airplanes. This proposed AD was prompted by reports of two failures... in this proposed AD, contact Gulfstream Aerospace Corporation, Technical Publications Dept., P.O....
78 FR 30243 - Airworthiness Directives; Eclipse Aerospace, Inc. Airplanes
2013-05-22
... Directives; Eclipse Aerospace, Inc. Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... all Eclipse Aerospace, Inc. Model EA500 airplanes equipped with Avio, Avio with ETT, or Avio NG 1.0... identified in this proposed AD, contact Eclipse Aerospace, Inc. 26 East Palatine Road, Wheeling,...
Modelling of Heat Transfer at the Solid to Solid Interface
Rywotycki M.
2016-03-01
Full Text Available In technological process of steel industry heat transfer is a very important factor. Heat transfer plays an essential role especially in rolling and forging processes. Heat flux between a tool and work piece is a function of temperature, pressure and time. A methodology for the determination of the heat transfer at solid to solid interface has been developed. It involves physical experiment and numerical methods. The first one requires measurements of the temperature variations at specified points in the two samples brought into contact. Samples made of C45 and NC6 steels have been employed in physical experiment. One of the samples was heated to an initial temperature of: 800°C, 1000°C and 1100°C. The second sample has been kept at room temperature. The numerical part makes use of the inverse method for calculating the heat flux and at the interface. The method involves the temperature field simulation in the axially symmetrical samples. The objective function is bulled up as a dimensionless error norm between measured and computed temperatures. The variable metric method is employed in the objective function minimization. The heat transfer coefficient variation in time at the boundary surface is approximated by cubic spline functions.
Elliptic solid-on-solid model's partition function as a single determinant
Galleas, W
2016-01-01
In this work we express the partition function of the integrable elliptic solid-on-solid model with domain-wall boundary conditions as a single determinant. This representation appears naturally as the solution of a system of functional equations governing the model's partition function.
Instabilities on crystal surfaces: The two-component body-centered solid-on-solid model
Carlon, E.; van Beijeren, H.; Mazzeo, G.
1996-01-01
The free energy of crystal surfaces that can be described by the two-component body-centered solid-on-solid model has been calculated in a mean-field approximation. The system may model ionic crystals with a bcc lattice structure (for instance CsCl). Crossings between steps are energetically favored
Modeling Degradation in Solid Oxide Electrolysis Cells
Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff
2010-09-01
Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.
2011-10-20
... configuration in the Gulfstream Model GIV-X passenger airplane. The Gulfstream Model GIV-X is a two-engine jet.... Mail: Send comments to Docket Operations, M-30, U.S. Department of Transportation (DOT), 1200 New... by Courier: Take comments to Docket Operations in Room W12-140 of the West Building Ground Floor...
Befrui, Bizhan A.
1995-01-01
This viewgraph presentation discusses the following: STAR-CD computational features; STAR-CD turbulence models; common features of industrial complex flows; industry-specific CFD development requirements; applications and experiences of industrial complex flows, including flow in rotating disc cavities, diffusion hole film cooling, internal blade cooling, and external car aerodynamics; and conclusions on turbulence modeling needs.
YANG Tao; BOZHKO, Serhiy; Asher, Greg
2015-01-01
This paper aims to develop a functional model of symmetrical multi-pulse Auto-Transformer Rectifier Units (ATRUs) for More-Electric Aircraft (MEA) applications. The ATRU is seen as the most reliable way readily to be applied in the MEA. Interestingly, there is no model of ATRUs suitable for unbalanced or faulty conditions at the moment. This paper is aimed to fill this gap and develop functional models suitable for both balanced and unbalanced conditions. Using the fact that the DC voltage an...
SPATIAL MODELING OF SOLID-STATE REGULAR POLYHEDRA (SOLIDS OF PLATON IN AUTOCAD SYSTEM
P. V. Bezditko
2009-03-01
Full Text Available This article describes the technology of modeling regular polyhedra by graphic methods. The authors came to the conclusion that in order to create solid models of regular polyhedra the method of extrusion is best to use.
Demerdash, N. A. O.
1976-01-01
The modes of operation of the brushless d.c. machine and its corresponding characteristics (current flow, torque-position, etc.) are presented. The foundations and basic principles on which the preliminary numerical model is based, are discussed.
75 FR 30282 - Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes
2010-06-01
.... Applicability (c) This AD applies to Model 11E airplanes, all serial numbers, that are certificated in any category. Subject (d) Air Transport Association of America (ATA) Code 27: Flight Controls. Unsafe Condition...
2011-11-01
rich low temperature chemistry Pressure: 1 atm DME model: Zhao et al., Int. J. Chem. Kinet ., (40) 2008 37 Flow tube experiments DME : rich low... Kinetic enhancement Fuel fragmentsTemperature increase Transport enhancementThermal enhancement Radicals H2, CO CH4 Understanding: Good poor O, NO O2(a∆g...plasma flame kinetic mechanism Develop numerical methods to achieve efficient modeling of detailed plasma flame chemistry 5 Outline 1. Background 2
Verification and Validation of ICME Methods and Models for Aerospace Applications
2012-06-11
most dominant and expected pro- cessing and behavioral mechanisms. Correspondingly, de- fining customer needs , the reality-of-interest, accuracy...chal- lenge some common shortcomings of materials modeling and include the following: Understanding customer needs An ICME model should serve a real...ICME predictions provide equal or better confidence than historical precedents. Dialog with the customer needs to continue throughout the ICME V&V
Integrated modeling for the manufacture of aerospace discs: Grain structure evolution
Kermanpur, A.; Lee, P. D.; McLean, M.; Tin, S.
2004-03-01
Process models of the various stages of gas turbine disc manufacture have been integrated to simulate the grain structure evolution of a nickel-based superalloy throughout the manufacturing route. The production of these critical structural components requires several distinct processing stages: vacuum induction melting, vacuum arc remelting, homogenization heat treatment, cogging, forging, final heat treatment, and machining. The microstructure, and hence properties, change significantly during these consecutive manufacturing stages due to the various thermal and thermo-mechanical treatments. Although separate models have previously been applied to the different processing stages, this article describes how these models can be integrated to track the microstructure of the part from secondary melting through to the final forging.
Smith, O. E.; Adelfang, S. I.
1998-01-01
The wind profile with all of its variations with respect to altitude has been, is now, and will continue to be important for aerospace vehicle design and operations. Wind profile databases and models are used for the vehicle ascent flight design for structural wind loading, flight control systems, performance analysis, and launch operations. This report presents the evolution of wind statistics and wind models from the empirical scalar wind profile model established for the Saturn Program through the development of the vector wind profile model used for the Space Shuttle design to the variations of this wind modeling concept for the X-33 program. Because wind is a vector quantity, the vector wind models use the rigorous mathematical probability properties of the multivariate normal probability distribution. When the vehicle ascent steering commands (ascent guidance) are wind biased to the wind profile measured on the day-of-launch, ascent structural wind loads are reduced and launch probability is increased. This wind load alleviation technique is recommended in the initial phase of vehicle development. The vehicle must fly through the largest load allowable versus altitude to achieve its mission. The Gumbel extreme value probability distribution is used to obtain the probability of exceeding (or not exceeding) the load allowable. The time conditional probability function is derived from the Gumbel bivariate extreme value distribution. This time conditional function is used for calculation of wind loads persistence increments using 3.5-hour Jimsphere wind pairs. These increments are used to protect the commit-to-launch decision. Other topics presented include the Shuttle Shuttle load-response to smoothed wind profiles, a new gust model, and advancements in wind profile measuring systems. From the lessons learned and knowledge gained from past vehicle programs, the development of future launch vehicles can be accelerated. However, new vehicle programs by their very
A Discrete Approach to Meshless Lagrangian Solid Modeling
Matthew Marko
2017-07-01
Full Text Available The author demonstrates a stable Lagrangian solid modeling method, tracking the interactions of solid mass particles rather than using a meshed grid. This numerical method avoids the problem of tensile instability often seen with smooth particle applied mechanics by having the solid particles apply stresses expected with Hooke’s law, as opposed to using a smoothing function for neighboring solid particles. This method has been tested successfully with a bar in tension, compression, and shear, as well as a disk compressed into a flat plate, and the numerical model consistently matched the analytical Hooke’s law as well as Hertz contact theory for all examples. The solid modeling numerical method was then built into a 2-D model of a pressure vessel, which was tested with liquid water particles under pressure and simulated with smoothed particle hydrodynamics. This simulation was stable, and demonstrated the feasibility of Lagrangian specification modeling for fluid–solid interactions.
2011-12-28
... G280 Airplane, Operation Without Normal Electrical Power AGENCY: Federal Aviation Administration (FAA... associated with operation without normal electrical power. The applicable airworthiness regulations do not... Model G280 will have a novel or unusual design feature associated with operation without...
2011-05-25
... INFORMATION CONTACT: Loran Haworth, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind... type certificate for their new Model G250 airplane. The G250 is an 8-10 passenger (19 maximum), twin... nautical miles. Airplane dimensions are 61.69-foot wing span, 66.6-foot overall length, and 20.8-foot...
2011-10-20
... passenger airplane. The Gulfstream Model GIV-X is a two-engine jet transport airplane with a maximum takeoff... Operations, M-30, U.S. Department of Transportation (DOT), 1200 New Jersey Avenue, SE., Room W12-140, West... Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue, SE., Washington,...
75 FR 45075 - Airworthiness Directives; Eclipse Aerospace, Inc. Model EA500 Airplanes
2010-08-02
... information system and the airplane flight manuals. The FAA incorrectly referenced the applicability for Model EA500 airplanes with certain serial numbers (SNs) of this proposed AD as ``000039 through 000104, 000113... incorporating changes to the electronic flight information system and the airplane flight manuals. In the...
2011-06-29
... LP Model Galaxy and Gulfstream 200 airplanes, certificated in any category, serial numbers 219 through 231 inclusive. Subject (d) Air Transport Association (ATA) of America Code 51: Standard Practices... A, dated January 25, 2010. (2) For airplanes having serial numbers 224 through 231 inclusive: Do the...
Hybrid finite-volume-ROM approach to non-linear aerospace fluid-structure interaction modelling
Mowat, AGB
2011-06-01
Full Text Available frame, describe the fluid domain while the structure is represented by a quadratic modal reduced order model (ROM). A Runge-Kutta dual-timestepping method is employed for the fluid solver, and three upwind schemes are considered viz. AUSM+ -up, HLLC...
Model predictions of latitude-dependent ozone depletion due to aerospace vehicle operations
Borucki, W. J.; Whitten, R. C.; Watson, V. R.; Riegel, C. A.; Maples, A. L.; Capone, L. A.
1976-01-01
Results are presented from a two-dimensional model of the stratosphere that simulates the seasonal movement of ozone by both wind and eddy transport, and contains all the chemistry known to be important. The calculated reductions in ozone due to NO2 injection from a fleet of supersonic transports are compared with the zonally averaged results of a three-dimensional model for a similar episode of injection. The agreement is good in the northern hemisphere, but is not as good in the southern hemisphere. Both sets of calculations show a strong corridor effect in that the predicted ozone depletions are largest to the north of the flight corridor for aircraft operating in the northern hemisphere.
Modeling of Residual Stress and Machining Distortion in Aerospace Components (PREPRINT)
2010-03-01
Quenched Superalloy Turbine Disc : Measurements and Modeling,” Metallurgical And Materials Transactions A Volume 37a, February 2006, 459. 7. D. Dye, K.T...order to produce a change in microstructure (e.g., phase transformation, recrystallization). Nickel base superalloy disks used in aircraft...nickel base superalloys . This step completes the transformation to a desired microstructure and 3 properties with the added benefit of stress relaxation
Development of temperature statistical model when machining of aerospace alloy materials
Kadirgama Kumaran
2014-01-01
Full Text Available This paper presents to develop first-order models for predicting the cutting temperature for end-milling operation of Hastelloy C-22HS by using four different coated carbide cutting tools and two different cutting environments. The first-order equations of cutting temperature are developed using the response surface methodology (RSM. The cutting variables are cutting speed, feed rate, and axial depth. The analyses are carried out with the aid of the statistical software package. It can be seen that the model is suitable to predict the longitudinal component of the cutting temperature close to those readings recorded experimentally with a 95% confident level. The results obtained from the predictive models are also compared with results obtained from finite-element analysis (FEA. The developed first-order equations for the cutting temperature revealed that the feed rate is the most crucial factor, followed by axial depth and cutting speed. The PVD coated cutting tools perform better than the CVD-coated cutting tools in terms of cutting temperature. The cutting tools coated with TiAlN perform better compared with other cutting tools during the machining performance of Hastelloy C-22HS. It followed by TiN/TiCN/TiN and CVD coated with TiN/TiCN/Al2O3 and TiN/TiCN/TiN. From the finite-element analysis, the distribution of the cutting temperature can be discussed. High temperature appears in the lower sliding friction zone and at the cutting tip of the cutting tool. Maximum temperature is developed at the rake face some distance away from the tool nose, however, before the chip lift away.
Development and validation of a strategic repositioning model for defense and aerospace contractors
Bers, John A.
Strategic repositioning refers to the organized efforts of defense contractors to "reposition" a technology that they have developed for a defense sector customer into a civilian or commercial market. The strategic repositioning model developed here is a structural model: it seeks to isolate the factors that influence choice of strategy, which in turn influences the organization's performance. The model draws from the prior experience of contractors (through interviews and surveys) and companies in other sectors (through a review of the relevant published research). (1) Over all, the model accounted for 55% of the variance in financial performance of the sample and 35% for the underlying population. (2) Key success factors include a rigorous planning process, a target market in the growth (vs. incubation) stage, a priority on market leadership as well as financial return, the ability to operate in an ambiguous business environment, and a relatively short time horizon but strong corporate support. (3) The greatest challenges that a contractor is likely to encounter are understanding his new customers' buying practices, strong competition, and adapting his technology to their needs and price expectations. (4) To address these issues contractors often involve partners in their entry strategy, but partnerships of equals tend to be more difficult to bring off than direct entry strategies. (5) The two major target market categories--government and commercial--present different challenges. Commercial customers are more likely to resist doing business with the contractor, while contractors entering government and other noncommercial markets are more likely to encounter price resistance, low technical sophistication among customers, and difficulties reaching their customer base. (6) Despite these differences across markets, performance is not influenced by the target market category, nor by the type of product or service or the contractor's functional orientation (marketing
Macroscopic modelling of solid-state fermentation
Hoogschagen, M.J.
2007-01-01
Solid-state fermentation is different from the more well known process of liquid fermentation because no free flowing water is present. The technique is primarily used in Asia. Well-known products are the foods tempe, soy sauce and saké. In industrial solid-state fermentation, the substrate usually
Using a Parametric Solid Modeler as an Instructional Tool
Devine, Kevin L.
2008-01-01
This paper presents the results of a quasi-experimental study that brought 3D constraint-based parametric solid modeling technology into the high school mathematics classroom. This study used two intact groups; a control group and an experimental group, to measure the extent to which using a parametric solid modeler during instruction affects…
Modeling for CVD of Solid Oxide Electrolyte
Starr, T.L.
2002-09-18
Because of its low thermal conductivity, high thermal expansion and high oxygen ion conductivity yttria-stabilized zirconia (YSZ) is the material of choice for high temperature electrolyte applications. Current coating fabrication methods have their drawbacks, however. Air plasma spray (APS) is a relatively low-cost process and is suitable for large and relatively complex shapes. it is difficult to produce uniform, relatively thin coatings with this process, however, and the coatings do not exhibit the columnar microstructure that is needed for reliable, long-term performance. The electron-beam physical vapor deposition (EB-PVD) process does produce the desirable microstructure, however, the capital cost of these systems is very high and the line-of-sight nature of the process limits coating uniformity and the ability to coat large and complex shapes. The chemical vapor deposition (CVD) process also produces the desirable columnar microstructure and--under proper conditions--can produce uniform coatings over complex shapes. CVD has been used for many materials but is relatively undeveloped for oxides, in general, and for zirconia, in particular. The overall goal of this project--a joint effort of the University of Louisville and Oak Ridge National Laboratory (ORNL)--is to develop the YSZ CVD process for high temperature electrolyte applications. This report describes the modeling effort at the University of Louisville, which supports the experimental work at ORNL. Early work on CVD of zirconia and yttria used metal chlorides, which react with water vapor to form solid oxide. Because of this rapid gas-phase reaction the water generally is formed in-situ using the reverse water-gas-shift reaction or a microwave plasma. Even with these arrangements gas-phase nucleation and powder formation are problems when using these precursors. Recent efforts on CVD of zirconia and YSZ have focused on use of metal-organic precursors (MOCVD). These are more stable in the gas
Procedures for Geometric Data Reduction in Solid Log Modelling
Luis G. Occeña; Wenzhen Chen; Daniel L. Schmoldt
1995-01-01
One of the difficulties in solid log modelling is working with huge data sets, such as those that come from computed axial tomographic imaging. Algorithmic procedures are described in this paper that have successfully reduced data without sacrificing modelling integrity.
Aerospace Materials Process Modelling
1988-08-01
deTresca La d~termination du coefficient de frottement de Tresca 9 est effectu~e de facon courante en forgeant un anneau de g~oan~trie fix~e. On mesure la...ailleurs et vaut a= 105 xt 0 , 2 5 Les riductions relatives du diam~tre int~rieur sont report~es sur l1abaque TVM(fig. 2a). Les coefficient de frottement ...validated material data bass. Information such as constitutive equations, intrinsic workability maps, effective heat-transfer coefficients , interface
Burn Rate Modelling of Solid Rocket Propellants (Short Communication
A.R. Kulkarni
1998-01-01
Full Text Available A generalised model of burning of a solid rocket propellant based on kinetics of propellant hasbeen developed. A complete set of variables has been formed after examining the existing models.Buckingham theorem provides the functional form of the model, such that the existing models are thesubcases of this generalised model. This proposed model has been validated by an experimental data.
Aerospace Systems Monitor Project
National Aeronautics and Space Administration — This Phase I STTR project will demonstrate the Aerospace System Monitor (ASM). This technology transforms the power distribution network in a spacecraft or aircraft...
Viscoelastic Modelling of Solid Rocket Propellants using Maxwell Fluid Model
Himanshu Shekhar
2010-07-01
Full Text Available Maxwell fluid model consisting of a spring and a dashpot in series is applied for viscoelastic characterisation of solid rocket propellants. Suitable values of spring constant and damping coefficient wereemployed by least square variation of errors for generation of complete stress-strain curve in uniaxial tensile mode for case-bonded solid propellant formulations. Propellants from the same lot were tested at different strain rates. It was observed that change in spring constant, representing elastic part was very small with strain rate but damping constant varies significantly with variation in strain rate. For a typical propellant formulation, when strain rate was raised from 0.00037/s to 0.185/s, spring constant K changed from 5.5 MPato 7.9 MPa, but damping coefficient D was reduced from 1400 MPa-s to 4 MPa-s. For all strain rates, stress-strain curve was generated using Maxwell model and close matching with actual test curve was observed.This indicates validity of Maxwell fluid model for uniaxial tensile testing curves of case-bonded solid propellant formulations. It was established that at higher strain rate, damping coefficient becomes negligible as compared to spring constant. It was also observed that variation of spring constant is logarithmic with strain rate and that of damping coefficient follows power law. The correlation coefficients were introduced to ascertain spring constants and damping coefficients at any strain rate from that at a reference strain rate. Correlationfor spring constant needs a coefficient H, which is function of propellant formulation alone and not of test conditions and the equation developeds K2 = K1 + H ´ ln{(de2/dt/(de1/dt}. Similarly for damping coefficient D also another constant S is introduced and prediction formula is given by D2 = D1 ´ {(de2/dt/(de1/dt}S.Evaluating constants H and S at different strain rates validate this mathematical formulation for differentpropellant formulations
A Local Composition Model for Paraffinic Solid Solutions
Coutinho, A.P. João; Knudsen, Kim; Andersen, Simon Ivar
1996-01-01
The description of the solid-phase non-ideality remains the main obstacle in modelling the solid-liquid equilibrium of hydrocarbons. A theoretical model, based on the local composition concept, is developed for the orthorhombic phase of n-alkanes and tested against experimental data for binary sy...... systems. It is shown that it can adequately predict the experimental phase behaviour of paraffinic mixtures. This work extends the applicability of local composition models to the solid phase. Copyright (C) 1996 Elsevier Science Ltd....
Advanced Materials and Coatings for Aerospace Applications
Miyoshi, Kazuhisa
2004-01-01
In the application area of aerospace tribology, researchers and developers must guarantee the highest degree of reliability for materials, components, and systems. Even a small tribological failure can lead to catastrophic results. The absence of the required knowledge of tribology, as Professor H.P. Jost has said, can act as a severe brake in aerospace vehicle systems-and indeed has already done so. Materials and coatings must be able to withstand the aerospace environments that they encounter, such as vacuum terrestrial, ascent, and descent environments; be resistant to the degrading effects of air, water vapor, sand, foreign substances, and radiation during a lengthy service; be able to withstand the loads, stresses, and temperatures encountered form acceleration and vibration during operation; and be able to support reliable tribological operations in harsh environments throughout the mission of the vehicle. This presentation id divided into two sections: surface properties and technology practice related to aerospace tribology. The first section is concerned with the fundamental properties of the surfaces of solid-film lubricants and related materials and coatings, including carbon nanotubes. The second is devoted to applications. Case studies are used to review some aspects of real problems related to aerospace systems to help engineers and scientists to understand the tribological issues and failures. The nature of each problem is analyzed, and the tribological properties are examined. All the fundamental studies and case studies were conducted at the NASA Glenn Research Center.
Mechanical and Aerospace Engineering
Millsaps, Knox T.; Gordis, J. H.; Brophy, C. M.; Stephens, Sandra
2008-01-01
This brochure explains the Mechanical and Aerospace Engineering program at the Naval Postgraduate School. Sections include: Advancing your career, student research, degree programs, special programs, research and distance learning programs. The Mechanical and Aerospace Engineering (MAE) Department, the founding department of the Naval Postgraduate School in 1909, offers a wide range of graduate degree programs including M.S. and Ph.D., in either Mechanical or Astronautical En...
Rheological and solid-state NMR assessments of copovidone/clotrimazole model solid dispersions.
Yang, Fengyuan; Su, Yongchao; Zhu, Lei; Brown, Chad D; Rosen, Lawrence A; Rosenberg, Kenneth J
2016-03-16
This study aims to assess several model solid dispersions by using dynamic oscillatory rheology, solid-state NMR and other solid phase characterization techniques, and correlate their viscoelastic responses with processing methods and microstructures. A model active pharmaceutical ingredient (API), clotrimazole, was compounded with copovidone to form solid dispersions via various techniques with different mixing capabilities. Physicochemical characterizations of the resulting solid dispersions demonstrated that simple physical mixing led to a poorly mixed blend manifested by existence of large API crystalline content and heterogeneous distribution. Cryogenic milling significantly improved mixing of two components as a result of reduced particle size and increased contact surface area, but produced limited amorphous content. In contrast, hot melt extrusion (HME) processing resulted in a homogenous amorphous solid dispersion because of its inherent mixing efficiency. Storage modulus and viscosities versus frequency of different solid dispersions indicated that the incorporation of API into the polymer matrix resulted in a plasticizing effect which reduced the viscosity. The crystalline/aggregated forms of API also exhibited more elastic response than its amorphous/dispersed counterpart. Temperature ramps of the physical mixture with high API concentration captured a critical temperature, at which a bump was observed in damping factor. This bump was attributed to the dissolution of crystalline API into the polymer. In addition, heating-cooling cycles of various solid dispersions suggested that cryomilling and HME processing could form a homogeneous solid dispersion at low API content, whereas high drug concentration led to a relatively unstable dispersion due to supersaturation of API in the polymer.
Modeling supercritical fluid extraction process involving solute-solid interaction
Goto, M.; Roy, B. Kodama, A.; Hirose, T. [Kumamoto Univ., Kumamoto (Japan)
1998-04-01
Extraction or leaching of solute from natural solid material is a mass transfer process involving dissolution or release of solutes from a solid matrix. Interaction between the solute and solid matrix often influences the supercritical fluid extraction process. A model accounting for the solute-solid interaction as well as mass transfer is developed. The BET equation is used to incorporate the interaction and the solubility of solutes into the local equilibrium in the model. Experimental data for the supercritical extraction of essential oil and cuticular wax from peppermint leaves are successfully analyzed by the model. The effects of parameters on the extraction behavior are demonstrated to illustrate the concept of the model. 18 refs., 5 figs., 1 tab.
Calculation of statistical entropic measures in a model of solids
Sanudo, Jaime
2012-01-01
In this work, a one-dimensional model of crystalline solids based on the Dirac comb limit of the Kronig-Penney model is considered. From the wave functions of the valence electrons, we calculate a statistical measure of complexity and the Fisher-Shannon information for the lower energy electronic bands appearing in the system. All these magnitudes present an extremal value for the case of solids having half-filled bands, a configuration where in general a high conductivity is attained in real solids, such as it happens with the monovalent metals.
Aerospace Accident - Injury Autopsy Data System -
Department of Transportation — The Aerospace Accident Injury Autopsy Database System will provide the Civil Aerospace Medical Institute (CAMI) Aerospace Medical Research Team (AMRT) the ability to...
Sliney, Harold E.
1993-01-01
The state of knowledge of solid lubricants is reviewed. The results of research on solid lubricants from the 1940's to the present are presented from a historical perspective. Emphasis is placed largely, but not exclusively, on work performed at NASA Lewis Research Center with a natural focus on aerospace applications. However, because of the generic nature of the research, the information presented in this review is applicable to most areas where solid lubricant technology is useful.
On the elliptic $\\mathfrak{gl}_2$ solid-on-solid model: functional relations and determinants
Galleas, W
2016-01-01
In this work we study an elliptic solid-on-solid model with domain-wall boundaries having the elliptic quantum group $\\mathcal{E}_{p, \\gamma}[\\widehat{\\mathfrak{gl}_2}]$ as its underlying symmetry algebra. We elaborate on results previously presented by the author and extend our analysis to include continuous families of single determinantal representations for the model's partition function. Interestingly, our families of representations are parameterized by two continuous complex variables which can be arbitrarily chosen without affecting the partition function.
Solid-on-solid model for surface growth in 2+1 dimensions
Hosseinabadi, S.; Masoudi, A. A.; Sadegh Movahed, M.
2010-04-01
We analyze in detail the solid-on-solid (SOS) model for growth processes on a square substrate in 2+1 dimensions. By using the Markovian surface properties, we introduce an alternative approach for determining the roughness exponent of a special type of SOS model-the restricted-solid-on-solid (RSOS) model-in 2+1 dimensions. This model is the SOS model with the additional restriction that the height difference must be S=1. Our numerical results show that the behavior of the SOS model in 2+1 dimensions for approximately S≥S×∼8 belongs to the two different universality classes: during the initial time stage, tChein and Pang (2004) [8]. Using the structure function, we compute the roughness exponent. In contrast to the growth exponent, the roughness exponent does not show crossover for different values of S. The scaling exponents of the structure function for fixed values of separation distance versus S in one and two space dimensions are ξ=0.92±0.05 and ξ=0.86±0.05 at 1σ confidence level, respectively.
Advanced methods of solid oxide fuel cell modeling
Milewski, Jaroslaw; Santarelli, Massimo; Leone, Pierluigi
2011-01-01
Fuel cells are widely regarded as the future of the power and transportation industries. Intensive research in this area now requires new methods of fuel cell operation modeling and cell design. Typical mathematical models are based on the physical process description of fuel cells and require a detailed knowledge of the microscopic properties that govern both chemical and electrochemical reactions. ""Advanced Methods of Solid Oxide Fuel Cell Modeling"" proposes the alternative methodology of generalized artificial neural networks (ANN) solid oxide fuel cell (SOFC) modeling. ""Advanced Methods
Aerogels in Aerospace: An Overview
Nadiir Bheekhun
2013-01-01
Full Text Available Aerogels are highly porous structures prepared via a sol-gel process and supercritical drying technology. Among the classes of aerogels, silica aerogel exhibits the most remarkable physical properties, possessing lower density, thermal conductivity, refractive index, and dielectric constant than any solids. Its acoustical property is such that it can absorb the sound waves reducing speed to 100 m/s compared to 332 m/s for air. However, when it comes to commercialization, the result is not as expected. It seems that mass production, particularly in the aerospace industry, has dawdled behind. This paper highlights the evolution of aerogels in general and discusses the functions and significances of silica aerogel in previous astronautical applications. Future outer-space applications have been proposed as per the current research trend. Finally, the implementation of conventional silica aerogel in aeronautics is argued with an alternative known as Maerogel.
Pinelli, Thomas E.; Kennedy, John M.; Barclay, Rebecca O.
1991-01-01
In this paper, the diffusion of federally funded aerospace R&D is explored from the perspective of the information-seeking behavior of U.S. aerospace engineers and scientists. The following three assumptions frame this exploration: (1) knowledge production, transfer, and utilization are equally important components of the aerospace R&D process; (2) the diffusion of knowledge resulting from federally funded aerospace R&D is indispensable for the U.S. to remain a world leader in aerospace; and (3) U.S. government technical reports, produced by NASA and DOD, play an important, but as yet undefined, role in the diffusion of federally funded aerospace R&D. A conceptual model for federally funded aerospace knowledge diffusion, one that emphasizes U.S. goverment technical reports, is presented. Data regarding three research questions concerning the information-seeking behavior of U.S. aerospace engineers and scientists are also presented.
MODELING A SOLID BOUNDARY AS A FLUID OF INFINITE VISCOSITY
无
2000-01-01
A new approach to model viscosity in the conservation of momentum equations is presented and discussed. Coefficient of viscosity is modeled in such a way that it reaches asymptotically to infinity at the solid boundary but still yields a finite value for the shear stress at the solid wall. Basic objective of this research is to show that certain combinations of higher order normal velocity gradients become zero at the solid boundary.Modified solutions for the Couette flow and Poiseuille flow between two parallel plates are obtained by modeling the coefficient of viscosity in a novel way. Also,viscous drag computed by our model is expected to yield higher values than the values predicted by the existing models, which matches closely to the experimental data.
Energy recovery from solid waste. [production engineering model
Dalton, C.; Huang, C. J.
1974-01-01
A recent group study on the problem of solid waste disposal provided a decision making model for a community to use in determining the future for its solid waste. The model is a combination of the following factors: technology, legal, social, political, economic and environmental. An assessment of local or community needs determines what form of energy recovery is desirable. A market for low pressure steam or hot water would direct a community to recover energy from solid waste by incineration to generate steam. A fuel gas could be produced by a process known as pyrolysis if there is a local market for a low heating value gaseous fuel. Solid waste can also be used directly as a fuel supplemental to coal in a steam generator. An evaluation of these various processes is made.
Energy recovery from solid waste. [production engineering model
Dalton, C.; Huang, C. J.
1974-01-01
A recent group study on the problem of solid waste disposal provided a decision making model for a community to use in determining the future for its solid waste. The model is a combination of the following factors: technology, legal, social, political, economic and environmental. An assessment of local or community needs determines what form of energy recovery is desirable. A market for low pressure steam or hot water would direct a community to recover energy from solid waste by incineration to generate steam. A fuel gas could be produced by a process known as pyrolysis if there is a local market for a low heating value gaseous fuel. Solid waste can also be used directly as a fuel supplemental to coal in a steam generator. An evaluation of these various processes is made.
Frontier Aerospace Opportunities
Bushnell, Dennis M.
2014-01-01
Discussion and suggested applications of the many ongoing technology opportunities for aerospace products and missions, resulting in often revolutionary capabilities. The, at this point largely unexamined, plethora of possibilities going forward, a subset of which is discussed, could literally reinvent aerospace but requires triage of many possibilities. Such initial upfront homework would lengthen the Research and Development (R&D) time frame but could greatly enhance the affordability and performance of the evolved products and capabilities. Structural nanotubes and exotic energetics along with some unique systems approaches are particularly compelling.
WATEQ3 geochemical model: thermodynamic data for several additional solids
Krupka, K.M.; Jenne, E.A.
1982-09-01
Geochemical models such as WATEQ3 can be used to model the concentrations of water-soluble pollutants that may result from the disposal of nuclear waste and retorted oil shale. However, for a model to competently deal with these water-soluble pollutants, an adequate thermodynamic data base must be provided that includes elements identified as important in modeling these pollutants. To this end, several minerals and related solid phases were identified that were absent from the thermodynamic data base of WATEQ3. In this study, the thermodynamic data for the identified solids were compiled and selected from several published tabulations of thermodynamic data. For these solids, an accepted Gibbs free energy of formation, ..delta..G/sup 0//sub f,298/, was selected for each solid phase based on the recentness of the tabulated data and on considerations of internal consistency with respect to both the published tabulations and the existing data in WATEQ3. For those solids not included in these published tabulations, Gibbs free energies of formation were calculated from published solubility data (e.g., lepidocrocite), or were estimated (e.g., nontronite) using a free-energy summation method described by Mattigod and Sposito (1978). The accepted or estimated free energies were then combined with internally consistent, ancillary thermodynamic data to calculate equilibrium constants for the hydrolysis reactions of these minerals and related solid phases. Including these values in the WATEQ3 data base increased the competency of this geochemical model in applications associated with the disposal of nuclear waste and retorted oil shale. Additional minerals and related solid phases that need to be added to the solubility submodel will be identified as modeling applications continue in these two programs.
A solid-fluid mixture model allowing for solid dilatation under external pressure
Sciarra, Giulio; Hutter, Kolumban
2010-01-01
A sponge subjected to an increase of the outside fluid pressure expands its volume but nearly mantains its true density and thus gives way to an increase of the interstitial volume. This behaviour, not yet properly described by solid-fluid mixture theories, is studied here by using the Principle of Virtual Power with the most simple dependence of the free energy as a function of the partial apparent densities of the solid and the fluid. The model is capable of accounting for the above mentioned dilatational behaviour, but in order to isolate its essential features more clearly we compromise on the other aspects of deformation.
Biomass torrefaction: modeling of volatile and solid product evolution kinetics.
Bates, Richard B; Ghoniem, Ahmed F
2012-11-01
The aim of this work is the development of a kinetics model for the evolution of the volatile and solid product composition during torrefaction conditions between 200 and 300°C. Coupled to an existing two step solid mass loss kinetics mechanism, this model describes the volatile release kinetics in terms of a set of identifiable chemical components, permitting the solid product composition to be estimated by mass conservation. Results show that most of the volatiles released during the first stage include highly oxygenated species such as water, acetic acid, and carbon dioxide, while volatiles released during the second step are composed primarily of lactic acid, methanol, and acetic acid. This kinetics model will be used in the development of a model to describe reaction energy balance and heat release dynamics.
2012-10-23
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Airplanes AGENCY... airworthiness directive (AD) for certain Gulfstream Aerospace LP (Type Certificate previously held by Israel... Certificate previously held by Israel Aircraft Industries, Ltd.) Model Galaxy and Gulfstream 200...
Aerospace Education. NSTA Position Statement
National Science Teachers Association (NJ1), 2008
2008-01-01
National Science Teachers Association (NSTA) has developed a new position statement, "Aerospace Education." NSTA believes that aerospace education is an important component of comprehensive preK-12 science education programs. This statement highlights key considerations that should be addressed when implementing a high quality aerospace education…
Study of Delft aerospace alumni
Smits, G.N.
2008-01-01
This thesis reports on an alumni study of the Faculty Aerospace Engineering at Delft University of Technology to discover what the impact is of the degree in aerospace engineering on an alumnus' professional success and comment on what are important qualities for aerospace engineers to have in order
A Thermodynamic Mixed-Solid Asphaltene Precipitation Model
Lindeloff, Niels; Heidemann, R.A.; Andersen, Simon Ivar
1998-01-01
A simple model for the prediction of asphaltene precipitation is proposed. The model is based on an equation of state and uses standard thermodynamics, thus assuming that the precipitation phenomenon is a reversible process. The solid phase is treated as an ideal multicomponent mixture. An activity...
2016-05-25
Airlines lamented, “[We are] now laggards in every category.”13 Once we were visionaries, and integrated aerospace was a core cultural , industrial...share of advanced technology jobs in the United States lags behind the Czech Republic, Slovenia, Germany, Hungary, Sweden , Finland, Italy, Denmark
Study on the control mechanism of China aerospace enterprises' binary multinational operation
Wang Jian; Li Hanling; Wu Weiwei
2008-01-01
China's aerospace enterprises carry on the multinational operation and participate in the international competition and the international division of labor and cooperation positively.This article first analyzs China aerospace enterprises' binary multinational business control objective and constructes its model.Then the article analyzes the tangible and intangible control mechanism of China aerospace enterprises' binary multinational operation respectively.Finally,the article constructs the model of China aerospace enterprises' binary multinational operation mechanisms.
Yang, Qingchun; Wang, Hongxin; Chetehouna, Khaled; Gascoin, Nicolas
2017-01-01
The supersonic combustion ramjet (scramjet) engine remains the most promising airbreathing engine cycle for hypersonic flight, particularly the high-performance dual-mode scramjet in the range of flight Mach number from 4 to 7, because it can operates under different combustion modes. Isolator is a very key component of the dual-mode scramjet engine. In this paper, nonlinear characteristics of combustion mode transition is theoretically analyzed. The discontinuous sudden changes of static pressure and Mach number are obtained as the mode transition occurs, which emphasizing the importance of predication and control of combustion modes. In this paper, a predication model of different combustion modes is developed based on these these nonlinear features in the isolator flow field. it can provide a valuable reference for control system design of the scramjet-powered aerospace vehicle.
Geometric data transfer between CAD systems: solid models
Kroszynski, Uri; Palstroem, Bjarne; Trostmann, Erik
1989-01-01
The first phase of the ESPRIT project CAD*I resulted in a specification for the exchange of solid models as well as in some pilot implementations of processors based on this specification. The authors summarize the CAD*I approach, addressing the structure of neutral files for solids, entities......, and attributes supporting three kinds of representations: facilities for the transfer of parametric designs; referencing library components; and other general mechanisms. They also describe the current state of the specification and processor implementations and include an example of a CAD*I neutral file....... Results from cycle and intersystem solid model transfer tests are presented, showing the practicality of the CAD*I proposal. B-rep model transfer results are discussed in some detail. The relationship of this work to standardization efforts is outlined...
Modeling and Design of Semi-Solid Flow Batteries
Brunini, Victor Eric
A three-dimensional dynamic model of the recently introduced semi-solid flow battery system is developed and applied to address issues with important design and operation implications. Because of the high viscosity of semi-solid flow battery suspensions, alternative modes of operation not typically used in conventional redox flow battery systems must be explored to reduce pumping energy losses. Modeling results are presented .and compared to experimental observations to address important considerations for both stoichiometric and intermittent flow operation. The importance of active material selection, and its impact on efficient stoichiometric flow operation is discussed. Electrochemically active zone considerations relevant to intermittent flow operation of semi-solid flow batteries (or other potential electronically conductive flow battery systems) are addressed. Finally, the use of the model as a design tool for optimizing flow channel design to improve system level performance is demonstrated.(Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)
Solid-on-solid model for surface growth in 2+1 dimensions
Hosseinabadi, S. [Department of Physics, Alzahra University, P.O. Box 19938, Tehran 91167 (Iran, Islamic Republic of); Masoudi, A.A., E-mail: amasoudi@math.uwaterloo.c [Department of Physics, Alzahra University, P.O. Box 19938, Tehran 91167 (Iran, Islamic Republic of); Department of Applied Mathematics, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada); Sadegh Movahed, M. [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of)
2010-04-15
We analyze in detail the solid-on-solid (SOS) model for growth processes on a square substrate in 2+1 dimensions. By using the Markovian surface properties, we introduce an alternative approach for determining the roughness exponent of a special type of SOS model-the restricted-solid-on-solid (RSOS) model-in 2+1 dimensions. This model is the SOS model with the additional restriction that the height difference must be S=1. Our numerical results show that the behavior of the SOS model in 2+1 dimensions for approximately S>=S{sub x}approx8 belongs to the two different universality classes: during the initial time stage, t
76 FR 55614 - Airworthiness Directives; Pacific Aerospace Limited Airplanes
2011-09-08
... Order 12866; 2. Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Pacific Aerospace... (AD) for Pacific Aerospace Limited Models FU24-954 and FU24A-954 airplanes modified with an...
Frischauf, Norbert; Acosta-Iborra, Beatriz; Harskamp, Frederik; Moretto, Pietro; Malkow, Thomas; Honselaar, Michel; Steen, Marc; Hovland, Scott; Hufenbach, Bernhard; Schautz, Max; Wittig, Manfred; Soucek, Alexander
2013-07-01
satellites. Similar trends can be expected in the future for RADAR Earth Observation satellites and space infrastructure concepts of great scale. This paper examines current activities along the hydrogen value chain, both in the terrestrial and the aerospace sector. A general assessment of the synergy potential is complemented by a thorough analysis of specific applications serving as role models like a lunar manned base or pressurised rover, an aircraft APU or a high power telecommunications satellite. Potential performance improvements and cost savings serve as key performance indicators in these comparisons and trade-offs.
Two types of glitches in a solid quark star model
Lu, Jiguang
2015-01-01
The glitch of anomalous X-ray pulsars \\& soft gamma repeaters (AXP/SGRs) usually accompanied with detectable energy releases manifesting as X-ray bursts or outbursts, while the glitch of some pulsars like Vela release negligible energy. We find that these two types of glitch can naturally correspond to two types of starquake of solid stars. So far only quark star and quark cluster star model develop a solid star model. Then the two types of glitch may be an implication that the pulsar is composed by quark matter or quark cluster matter.
A user-friendly modified pore-solid fractal model
Dian-yuan Ding; Ying Zhao; Hao Feng; Bing-cheng Si; Robert Lee Hill
2016-01-01
The primary objective of this study was to evaluate a range of calculation points on water retention curves (WRC) instead of the singularity point at air-entry suction in the pore-solid fractal (PSF) model, which additionally considered the hysteresis effect based on the PSF theory. The modified pore-solid fractal (M-PSF) model was tested using 26 soil samples from Yangling on the Loess Plateau in China and 54 soil samples from the Unsaturated Soil Hydraulic Database. The derivation results s...
Phase field modeling of flexoelectricity in solid dielectrics
Chen, H. T.; Zhang, S. D.; Soh, A. K.; Yin, W. Y.
2015-07-01
A phase field model is developed to study the flexoelectricity in nanoscale solid dielectrics, which exhibit both structural and elastic inhomogeneity. The model is established for an elastic homogeneous system by taking into consideration all the important non-local interactions, such as electrostatic, elastic, polarization gradient, as well as flexoelectric terms. The model is then extended to simulate a two-phase system with strong elastic inhomogeneity. Both the microscopic domain structures and the macroscopic effective piezoelectricity are thoroughly studied using the proposed model. The results obtained show that the largest flexoelectric induced polarization exists at the interface between the matrix and the inclusion. The effective piezoelectricity is greatly influenced by the inclusion size, volume fraction, elastic stiffness, and the applied stress. The established model in the present study can provide a fundamental framework for computational study of flexoelectricity in nanoscale solid dielectrics, since various boundary conditions can be easily incorporated into the phase field model.
Developing and modelling of ohmic heating for solid food products
Feyissa, Aberham Hailu; Frosch, Stina
such as meat and seafood is not industrially utilized yet. Therefore, the aim of the current work is to model and develop the ohmic heating technology for heating of solid meat and seafood. A 3D mathematical model of coupled heat transfer and electric field during ohmic heating of meat products has been......Heating of solid foods using the conventional technologies is time-consuming due to the fact that heat transfer is limited by internal conduction within the product. This is a big challenge to food manufactures who wish to heat the product faster to the desired core temperature and to ensure more...... uniform quality across the product. Ohmic heating is one of the novel technologies potentially solving this problem by allowing volumetric heating of the product and thereby reducing or eliminating temperature gradients within the product. However, the application of ohmic heating for solid food products...
Managing complexity of aerospace systems
Tamaskar, Shashank
Growing complexity of modern aerospace systems has exposed the limits of conventional systems engineering tools and challenged our ability to design them in a timely and cost effective manner. According to the US Government Accountability Office (GAO), in 2009 nearly half of the defense acquisition programs are expecting 25% or more increase in unit acquisition cost. Increase in technical complexity has been identified as one of the primary drivers behind cost-schedule overruns. Thus to assure the affordability of future aerospace systems, it is increasingly important to develop tools and capabilities for managing their complexity. We propose an approach for managing the complexity of aerospace systems to address this pertinent problem. To this end, we develop a measure that improves upon the state-of-the-art metrics and incorporates key aspects of system complexity. We address the problem of system decomposition by presenting an algorithm for module identification that generates modules to minimize integration complexity. We demonstrate the framework on diverse spacecraft and show the impact of design decisions on integration cost. The measure and the algorithm together help the designer track and manage complexity in different phases of system design. We next investigate how complexity can be used as a decision metric in the model-based design (MBD) paradigm. We propose a framework for complexity enabled design space exploration that introduces the idea of using complexity as a non-traditional design objective. We also incorporate complexity with the component based design paradigm (a sub-field of MBD) and demonstrate it on several case studies. The approach for managing complexity is a small but significant contribution to the vast field of complexity management. We envision our approach being used in concert with a suite of complexity metrics to provide an ability to measure and track complexity through different stages of design and development. This will not
Explicit Modeling of Solid Ocean Floor in Shallow Underwater Explosions
A.P. Walters
2013-01-01
Full Text Available Current practices for modeling the ocean floor in underwater explosion simulations call for application of an inviscid fluid with soil properties. A method for modeling the ocean floor as a Lagrangian solid, vice an Eulerian fluid, was developed in order to determine its effects on underwater explosions in shallow water using the DYSMAS solver. The Lagrangian solid bottom model utilized transmitting boundary segments, exterior nodal forces acting as constraints, and the application of prestress to minimize any distortions into the fluid domain. For simplicity, elastic materials were used in this current effort, though multiple constitutive soil models can be applied to improve the overall accuracy of the model. Even though this method is unable to account for soil cratering effects, it does however provide the distinct advantage of modeling contoured ocean floors such as dredged channels and sloped bottoms absent in Eulerian formulations. The study conducted here showed significant differences among the initial bottom reflections for the different solid bottom contours that were modeled. The most important bottom contour effect was the distortion to the gas bubble and its associated first pulse timing. In addition to its utility in bottom modeling, implementation of the non-reflecting boundary along with realistic material models can be used to drastically reduce the size of current fluid domains.
Adaptive control with aerospace applications
Gadient, Ross
Robust and adaptive control techniques have a rich history of theoretical development with successful application. Despite the accomplishments made, attempts to combine the best elements of each approach into robust adaptive systems has proven challenging, particularly in the area of application to real world aerospace systems. In this research, we investigate design methods for general classes of systems that may be applied to representative aerospace dynamics. By combining robust baseline control design with augmentation designs, our work aims to leverage the advantages of each approach. This research contributes the development of robust model-based control design for two classes of dynamics: 2nd order cascaded systems, and a more general MIMO framework. We present a theoretically justified method for state limiting via augmentation of a robust baseline control design. Through the development of adaptive augmentation designs, we are able to retain system performance in the presence of uncertainties. We include an extension that combines robust baseline design with both state limiting and adaptive augmentations. In addition we develop an adaptive augmentation design approach for a class of dynamic input uncertainties. We present formal stability proofs and analyses for all proposed designs in the research. Throughout the work, we present real world aerospace applications using relevant flight dynamics and flight test results. We derive robust baseline control designs with application to both piloted and unpiloted aerospace system. Using our developed methods, we add a flight envelope protecting state limiting augmentation for piloted aircraft applications and demonstrate the efficacy of our approach via both simulation and flight test. We illustrate our adaptive augmentation designs via application to relevant fixed-wing aircraft dynamics. Both a piloted example combining the state limiting and adaptive augmentation approaches, and an unpiloted example with
Solid waste integrated cost analysis model: 1991 project year report
1991-01-01
The purpose of the City of Houston's 1991 Solid Waste Integrated Cost Analysis Model (SWICAM) project was to continue the development of a computerized cost analysis model. This model is to provide solid waste managers with tool to evaluate the dollar cost of real or hypothetical solid waste management choices. Those choices have become complicated by the implementation of Subtitle D of the Resources Conservation and Recovery Act (RCRA) and the EPA's Integrated Approach to managing municipal solid waste;. that is, minimize generation, maximize recycling, reduce volume (incinerate), and then bury (landfill) only the remainder. Implementation of an integrated solid waste management system involving all or some of the options of recycling, waste to energy, composting, and landfilling is extremely complicated. Factors such as hauling distances, markets, and prices for recyclable, costs and benefits of transfer stations, and material recovery facilities must all be considered. A jurisdiction must determine the cost impacts of implementing a number of various possibilities for managing, handling, processing, and disposing of waste. SWICAM employs a single Lotus 123 spreadsheet to enable a jurisdiction to predict or assess the costs of its waste management system. It allows the user to select his own process flow for waste material and to manipulate the model to include as few or as many options as he or she chooses. The model will calculate the estimated cost for those choices selected. The user can then change the model to include or exclude waste stream components, until the mix of choices suits the user. Graphs can be produced as a visual communication aid in presenting the results of the cost analysis. SWICAM also allows future cost projections to be made.
High power solid state retrofit lamp thermal characterization and modeling
Jakovenko, J.; Formánek, J.; Vladimír, J.; Husák, M.; Werkhoven, R.J.
2012-01-01
Thermal and thermo-mechanical modeling and characterization of solid state lightening (SSL) retrofit LED Lamp are presented in this paper. Paramount Importance is to design SSL lamps for reliability, in which thermal and thermo-mechanical aspects are key points. The main goal is to get a precise 3D
2011-10-13
... Directives; Eclipse Aerospace, Inc. Airplanes Equipped With Pratt & Whitney Canada, Corp. PW610F-A Engines...: We propose to revise an existing airworthiness directive (AD) that applies to all Eclipse Aerospace... 10, 2011), for all Eclipse Aerospace, Inc. Model EA500 airplanes equipped with Pratt & Whitney...
2010-05-21
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Model Gulfstream 100... adding the following new AD: 2010-11-02 Gulfstream Aerospace LP (Type Certificate Previously Held by... Gulfstream Aerospace LP (Type Certificate previously held by Israel Aircraft Industries, Ltd.)...
An integration scheme for stiff solid-gas reactor models
Bjarne A. Foss
2001-04-01
Full Text Available Many dynamic models encounter numerical integration problems because of a large span in the dynamic modes. In this paper we develop a numerical integration scheme for systems that include a gas phase, and solid and liquid phases, such as a gas-solid reactor. The method is based on neglecting fast dynamic modes and exploiting the structure of the algebraic equations. The integration method is suitable for a large class of industrially relevant systems. The methodology has proven remarkably efficient. It has in practice performed excellent and been a key factor for the success of the industrial simulator for electrochemical furnaces for ferro-alloy production.
Modeling steel deformation in the semi-solid state
Hojny, Marcin
2017-01-01
This book addresses selected aspects of steel-deformation modelling, both at very high temperatures and under the conditions in which the liquid and the solid phases coexist. Steel-deformation modelling with its simultaneous solidification is particularly difficult due to its specificity and complexity. With regard to industrial applications and the development of new, integrated continuous casting and rolling processes, the issues related to modelling are becoming increasingly important. Since the numerous industrial tests that are necessary when traditional methods are used to design the process of continuous casting immediately followed by rolling are expensive, new modelling concepts have been sought. Comprehensive tests were applied to solve problems related to the deformation of steel with a semi-solid core. Physical tests using specialist laboratory instruments (Gleeble 3800thermo-mechanical simulator, NANOTOM 180 N computer tomography, Zwick Z250 testing equipment, 3D blue-light scanning systems), and...
Modeling of ionic transport in solid polymer electrolytes
Cheang, P L; Teo, L L; Lim, T L, E-mail: plcheang@mmu.edu.my [Centre for Foundation Studies and Extension Education, Multimedia University, Jln Ayer Keroh Lama, 75450 Melaka (Malaysia)
2010-05-15
A Monte Carlo model describing the ionic trans port in solid polyme relectrolyte is developed. Single cation simulation is carried out using hopping rate to study the transport mechanism of a thermally activated ion in solid polymer electrolyte. In our model, the ion is able to hop along a polymer chain and to jump between different chains, surmounting energy barriers that consist of polymer's activation energy and the externally applied electric field. The model is able to trace the motion of ion across polymer electrolyte. The mean hopping distance is calculated based on the available open bond in the next nearest side. Random numbers are used to determine the hopping distances, free flight times, final energy and direction of the cation after successful hop. Drift velocity and energy of cation are simulated in our work. The model is expected to be able to simulate the lithium-polymer battery in future.
Modeling effective viscosity reduction behaviour of solid suspensions
Wei En-Bo; Ji Yan-Ju; Zhang Jun
2012-01-01
Under a simple shearing flow,the effective viscosity of solid suspensions can be reduced by controlling the inclusion particle size or the number of inclusion particles in a unit volume.Based on the Stokes equation,the transformation field method is used to model the reduction behaviour of effective viscosity of solid suspensions theoretically by enlarging the particle size at a given high concentration of particles.With a lot of samples of random cubic particles in a unit cell,our statistical results show that at the same higher concentration,the effective viscosity of solid suspensions can be reduced by increasing the particle size or reducing the number of inclusion particles in a unit volume.This work discloses the viscosity reduction mechanism of increasing particle size,which is observed experimentally.
Leung, Kevin
2015-03-01
Electrochemical reactions at electrode/electrolyte interfaces are critically dependent on the total electrochemical potential or voltage. In this presentation, we briefly review ab initio molecular dynamics (AIMD)-based estimate of voltages on graphite basal and edge planes, and then apply similar concepts to solid-solid interfaces relevant to lithium ion and Li-air batteries. Thin solid films on electrode surfaces, whether naturally occuring during power cycling (e.g., undesirable lithium carbonate on Li-air cathodes) or are artificially introduced, can undergo electrochemical reactions as the applied voltage varies. Here the onset of oxidation of lithium carbonate and other oxide thin films on model gold electrode surfaces is correlated with the electronic structure in the presence/absence of solvent molecules. Our predictions help determine whether oxidation first occurs at the electrode-thin film or electrolyte-thin film interface. Finally, we will critically compare the voltage estimate methodology used in the fuel cell community with the lithium cohesive energy calibration method broadly applied in the battery community, and discuss why they may yield different predictions. This work was supported by Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001160. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
SRM (Solid Rocket Motor) propellant and polymer materials structural modeling
Moore, Carleton J.
1988-01-01
The following investigation reviews and evaluates the use of stress relaxation test data for the structural analysis of Solid Rocket Motor (SRM) propellants and other polymer materials used for liners, insulators, inhibitors, and seals. The stress relaxation data is examined and a new mathematical structural model is proposed. This model has potentially wide application to structural analysis of polymer materials and other materials generally characterized as being made of viscoelastic materials. A dynamic modulus is derived from the new model for stress relaxation modulus and is compared to the old viscoelastic model and experimental data.
Modeling the diffusion of solid copper into liquid solder alloys
Rizvi, M.J. [School of Computing and Mathematical Sciences, University of Greenwich, 30 Park Row, London, SE10 9LS (United Kingdom)], E-mail: rm77@gre.ac.uk; Lu, H.; Bailey, C. [School of Computing and Mathematical Sciences, University of Greenwich, 30 Park Row, London, SE10 9LS (United Kingdom)
2009-01-01
During the soldering process, the copper atoms diffuse into liquid solders. The diffusion process determines integrity and the reworking possibility of a solder joint. In order to capture the diffusion scenarios of solid copper into liquid Sn-Pb and Sn-Cu solders, a computer modeling has been performed for 10 s. An analytical model has also been proposed for calculating the diffusion coefficient of copper into liquid solders. It is found that the diffusion coefficient for Sn-Pb solder is 2.74 x 10{sup -10} m{sup 2}/s and for Sn-Cu solder is 6.44 x 10{sup -9} m{sup 2}/s. The modeling results reveal that the diffusion coefficient is one of the major factors that govern the rate at which solid Cu dissolve in the molten solder. The predicted dissolved amounts of copper into solders have been validated with the help of scanning electron microscopic analysis.
CSIR
2006-12-01
Full Text Available fighter aircraft, or additional applications in other areas such as the automotive and power generation industries. Aerospace capabilities are essential to national safety and security. A large proportion of products in the aerospace sector has... of the technology is perva- sive and can, as such, be refined to fulfil the harsh environmental parameters required in both near and outer space. Technologies focusing on the aerospace sector are also likely to find application in the automotive...
MODELING AND SIMULATION OF SOLID FLUIDIZATION IN A RESIN COLUMN
Lee, S.
2014-06-24
The objective of the present work is to model the resin particles within the column during fluidization and sedimentation processes using computation fluid dynamics (CFD) approach. The calculated results will help interpret experimental results, and they will assist in providing guidance on specific details of testing design and establishing a basic understanding of particle’s hydraulic characteristics within the column. The model is benchmarked against the literature data and the test data (2003) conducted at Savannah River Site (SRS). The paper presents the benchmarking results and the modeling predictions of the SRS resin column using the improved literature correlations applicable for liquid-solid granular flow.
A lumped model for rotational modes in periodic solid composites
Peng, Pai
2013-10-01
We present a lumped model to study the rotational modes in a type of two-dimensional periodic solid composites comprised of a square array of rubber-coated steel cylinders embedded in an epoxy matrix. The model captures the physical essence of rotational modes in such systems for various combinations of material parameters, and, therefore it is able to describe the transition behaviour when the system is gradually adjusted from an elastic metamaterial to an elastic phononic crystal. From the model, we can define a transition zone which separates the typical elastic metamaterials and the phononic crystals.
A Liquid-Solid Coupling Hemodynamic Model with Microcirculation Load
Bai Li
2016-01-01
Full Text Available From the aspect of human circulation system structure, a complete hemodynamic model requires consideration of the influence of microcirculation load effect. This paper selected the seepage in porous media as the simulant of microcirculation load. On the basis of a bi-directional liquid-solid coupling tube model, we built a liquid-solid-porous media seepage coupling model. The simulation parameters accorded with the physiological reality. Inlet condition was set as transient single-pulse velocity, and outlet as free outlet. The pressure in the tube was kept at the state of dynamic stability in the range of 80–120 mmHg. The model was able to simulate the entire propagating process of pulse wave. The pulse wave velocity simulated was 6.25 m/s, which accorded with the physiological reality. The complex pressure wave shape produced by reflections of pressure wave was also observed. After the model changed the cardiac cycle length, the pressure change according with actual human physiology was simulated successfully. The model in this paper is well-developed and reliable. It demonstrates the importance of microcirculation load in hemodynamic model. Moreover the properties of the model provide a possibility for the simulation of dynamic adjustment process of human circulation system, which indicates a promising prospect in clinical application.
Advanced impedance modeling of solid oxide electrochemical cells
Graves, Christopher R.; Hjelm, Johan
2014-01-01
Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number o...... analysis methods and integrates the analysis process in a modular workflow – data validation (Kramers-Kronig), clean-up, visualization (DRT and others), modeling (nonlinear least-squares fitting), and final plotting for publication....
Impedance Modeling of Solid Oxide Fuel Cell Cathodes
Mortensen, Jakob Egeberg; Søgaard, Martin; Jacobsen, Torben
2010-01-01
A 1-dimensional impedance model for a solid oxide fuel cell cathode is formulated and applied to a cathode consisting of 50/50 wt% strontium doped lanthanum cobaltite and gadolinia doped ceria. A total of 42 impedance spectra were recorded in the temperature range: 555-852°C and in the oxygen...... physical parameters such as the cathode thickness. ©2010 COPYRIGHT ECS - The Electrochemical Society...
Design Through Manufacturing: The Solid Model - Finite Element Analysis Interface
Rubin, Carol
2003-01-01
State-of-the-art computer aided design (CAD) presently affords engineers the opportunity to create solid models of machine parts which reflect every detail of the finished product. Ideally, these models should fulfill two very important functions: (1) they must provide numerical control information for automated manufacturing of precision parts, and (2) they must enable analysts to easily evaluate the stress levels (using finite element analysis - FEA) for all structurally significant parts used in space missions. Today's state-of-the-art CAD programs perform function (1) very well, providing an excellent model for precision manufacturing. But they do not provide a straightforward and simple means of automating the translation from CAD to FEA models, especially for aircraft-type structures. The research performed during the fellowship period investigated the transition process from the solid CAD model to the FEA stress analysis model with the final goal of creating an automatic interface between the two. During the period of the fellowship a detailed multi-year program for the development of such an interface was created. The ultimate goal of this program will be the development of a fully parameterized automatic ProE/FEA translator for parts and assemblies, with the incorporation of data base management into the solution, and ultimately including computational fluid dynamics and thermal modeling in the interface.
Nondestructive Evaluation for Aerospace Composites
Leckey, Cara; Cramer, Elliott; Perey, Daniel
2015-01-01
Nondestructive evaluation (NDE) techniques are important for enabling NASA's missions in space exploration and aeronautics. The expanded and continued use of composite materials for aerospace components and vehicles leads to a need for advanced NDE techniques capable of quantitatively characterizing damage in composites. Quantitative damage detection techniques help to ensure safety, reliability and durability of space and aeronautic vehicles. This presentation will give a broad outline of NASA's range of technical work and an overview of the NDE research performed in the Nondestructive Evaluation Sciences Branch at NASA Langley Research Center. The presentation will focus on ongoing research in the development of NDE techniques for composite materials and structures, including development of automated data processing tools to turn NDE data into quantitative location and sizing results. Composites focused NDE research in the areas of ultrasonics, thermography, X-ray computed tomography, and NDE modeling will be discussed.
77 FR 71357 - Airworthiness Directives; Pacific Aerospace Limited Airplanes
2012-11-30
... applies to Pacific Aerospace Limited Models FU24-954 and FU24A-954 airplanes, all serial numbers, that are... Transport Association of America (ATA) Code 8: Leveling and Weighing. (e) Reason This AD was prompted by...
Modeling of Brain Shift Phenomenon for Different Craniotomies and Solid Models
Alvaro Valencia
2012-01-01
Full Text Available This study investigates the effects of different solid models on predictions of brain shift for three craniotomies. We created a generic 3D brain model based on healthy human brain and modeled the brain parenchyma as single continuum and constrained by a practically rigid skull. We have used elastic model, hyperelastic 1st, 2nd, and 3rd Ogden models, and hyperelastic Mooney-Rivlin with 2- and 5-parameter models. A pressure on the brain surface at craniotomy region was applied to load the model. The models were solved with the finite elements package ANSYS. The predictions on stress and displacements were compared for three different craniotomies. The difference between the predictions of elastic solid model and a hyperelastic Ogden solid model of maximum brain displacement and maximum effective stress is relevant.
MODELING OF TEMPERATURE FIELDS IN A SOLID HEAT ACCUMULLATORS
S. S. Belimenko
2016-10-01
Full Text Available Purpose. Currently, one of the priorities of energy conservation is a cost savings for heating in commercial and residential buildings by the stored thermal energy during the night and its return in the daytime. Economic effect is achieved due to the difference in tariffs for the cost of electricity in the daytime and at night. One of the most common types of devices that allow accumulating and giving the resulting heat are solid heat accumulators. The main purpose of the work: 1 software development for the calculation of the temperature field of a flat solid heat accumulator, working due to the heat energy accumulation in the volume of thermal storage material without phase transition; 2 determination the temperature distribution in its volumes at convective heat transfer. Methodology. To achieve the study objectives a heat transfer theory and Laplace integral transform were used. On its base the problems of determining the temperature fields in the channels of heat accumulators, having different cross-sectional shapes were solved. Findings. Authors have developed the method of calculation and obtained solutions for the determination of temperature fields in channels of the solid heat accumulator in conditions of convective heat transfer. Temperature fields over length and thickness of channels were investigated. Experimental studies on physical models and industrial equipment were conducted. Originality. For the first time the technique of calculating the temperature field in the channels of different cross-section for the solid heat accumulator in the charging and discharging modes was proposed. The calculation results are confirmed by experimental research. Practical value. The proposed technique is used in the design of solid heat accumulators of different power as well as full-scale production of them was organized.
A user-friendly modified pore-solid fractal model
Ding, Dian-Yuan; Zhao, Ying; Feng, Hao; Si, Bing-Cheng; Hill, Robert Lee
2016-12-01
The primary objective of this study was to evaluate a range of calculation points on water retention curves (WRC) instead of the singularity point at air-entry suction in the pore-solid fractal (PSF) model, which additionally considered the hysteresis effect based on the PSF theory. The modified pore-solid fractal (M-PSF) model was tested using 26 soil samples from Yangling on the Loess Plateau in China and 54 soil samples from the Unsaturated Soil Hydraulic Database. The derivation results showed that the M-PSF model is user-friendly and flexible for a wide range of calculation point options. This model theoretically describes the primary differences between the soil moisture desorption and the adsorption processes by the fractal dimensions. The M-PSF model demonstrated good performance particularly at the calculation points corresponding to the suctions from 100 cm to 1000 cm. Furthermore, the M-PSF model, used the fractal dimension of the particle size distribution, exhibited an accepted performance of WRC predictions for different textured soils when the suction values were ≥100 cm. To fully understand the function of hysteresis in the PSF theory, the role of allowable and accessible pores must be examined.
Facility for cold flow testing of solid rocket motor models
Bacchus, D. L.; Hill, O. E.; Whitesides, R. Harold
1992-02-01
A new cold flow test facility was designed and constructed at NASA Marshall Space Flight Center for the purpose of characterizing the flow field in the port and nozzle of solid propellant rocket motors (SRM's). A National Advisory Committee was established to include representatives from industry, government agencies, and universities to guide the establishment of design and instrumentation requirements for the new facility. This facility design includes the basic components of air storage tanks, heater, submicron filter, quiet control valve, venturi, model inlet plenum chamber, solid rocket motor (SRM) model, exhaust diffuser, and exhaust silencer. The facility was designed to accommodate a wide range of motor types and sizes from small tactical motors to large space launch boosters. This facility has the unique capability of testing ten percent scale models of large boosters such as the new Advanced Solid Rocket Motor (ASRM), at full scale motor Reynolds numbers. Previous investigators have established the validity of studying basic features of solid rocket motor development programs include the acquisition of data to (1) directly evaluate and optimize the design configuration of the propellant grain, insulation, and nozzle; and (2) provide data for validation of the computational fluid dynamics, (CFD), analysis codes and the performance analysis codes. A facility checkout model was designed, constructed, and utilized to evaluate the performance characteristics of the new facility. This model consists of a cylindrical chamber and converging/diverging nozzle with appropriate manifolding to connect it to the facility air supply. It was designed using chamber and nozzle dimensions to simulate the flow in a 10 percent scale model of the ASRM. The checkout model was recently tested over the entire range of facility flow conditions which include flow rates from 9.07 to 145 kg/sec (20 to 320 Ibm/sec) and supply pressure from 5.17 x 10 exp 5 to 8.27 x 10 exp 6 Pa. The
Modelling temperature and concentration dependent solid/liquid interfacial energies
Lippmann, Stephanie; Jung, In-Ho; Paliwal, Manas; Rettenmayr, Markus
2016-01-01
Models for the prediction of the solid/liquid interfacial energy in pure substances and binary alloys, respectively, are reviewed and extended regarding the temperature and concentration dependence of the required thermodynamic entities. A CALPHAD-type thermodynamic database is used to introduce temperature and concentration dependent melting enthalpies and entropies for multicomponent alloys in the temperature range between liquidus and solidus. Several suitable models are extended and employed to calculate the temperature and concentration dependent interfacial energy for Al-FCC with their respective liquids and compared with experimental data.
Modeling of efficient solid-state cooler on layered multiferroics.
Starkov, Ivan; Starkov, Alexander
2014-08-01
We have developed theoretical foundations for the design and optimization of a solid-state cooler working through caloric and multicaloric effects. This approach is based on the careful consideration of the thermodynamics of a layered multiferroic system. The main section of the paper is devoted to the derivation and solution of the heat conduction equation for multiferroic materials. On the basis of the obtained results, we have performed the evaluation of the temperature distribution in the refrigerator under periodic external fields. A few practical examples are considered to illustrate the model. It is demonstrated that a 40-mm structure made of 20 ferroic layers is able to create a temperature difference of 25K. The presented work tries to address the whole hierarchy of physical phenomena to capture all of the essential aspects of solid-state cooling.
Eisemann, Ulrich
2016-01-01
International audience; The new standard for software development in civil aviation, DO-178C, mainly differs from its predecessor DO-178B, in that it has standard supplements to provide greater scope for using new software development methods. The most important standard supplements are DO-331 on the methods of model-based development and model-based verification and DO-333 on the use of formal methods such as model checking and abstract interpretation. These key software design techniques of...
SSM - SOLID SURFACE MODELER, VERSION 6.0
Goza, S. P.
1994-01-01
The Solid Surface Modeler (SSM) is an interactive graphics software application for solid-shaded and wireframe three- dimensional geometric modeling. It enables the user to construct models of real-world objects as simple as boxes or as complex as Space Station Freedom. The program has a versatile user interface that, in many cases, allows mouse input for intuitive operation or keyboard input when accuracy is critical. SSM can be used as a stand-alone model generation and display program and offers high-fidelity still image rendering. Models created in SSM can also be loaded into other software for animation or engineering simulation. (See the information below for the availability of SSM with the Object Orientation Manipulator program, OOM, a graphics software application for three-dimensional rendering and animation.) Models are constructed within SSM using functions of the Create Menu to create, combine, and manipulate basic geometric building blocks called primitives. Among the simpler primitives are boxes, spheres, ellipsoids, cylinders, and plates; among the more complex primitives are tubes, skinned-surface models and surfaces of revolution. SSM also provides several methods for duplicating models. Constructive Solid Geometry (CSG) is one of the most powerful model manipulation tools provided by SSM. The CSG operations implemented in SSM are union, subtraction and intersection. SSM allows the user to transform primitives with respect to each axis, transform the camera (the user's viewpoint) about its origin, apply texture maps and bump maps to model surfaces, and define color properties; to select and combine surface-fill attributes, including wireframe, constant, and smooth; and to specify models' points of origin (the positions about which they rotate). SSM uses Euler angle transformations for calculating the results of translation and rotation operations. The user has complete control over the modeling environment from within the system. A variety of file
模型成熟度驱动的航天IPT协同研制模式研究%Research on Cooperative Model of Aerospace IPT Driven by Model Maturity
王红雨; 顾翠; 敬石开
2013-01-01
According to the characteristics of the aerospace research and the requirement for MBD is the only data source, the model maturity and the concept of MBD data are discussed. Research on how to build an IPT team and how to raise the efficiency of the IPT team under the existing aerospace system. Finally, the maturity model is applied to the parallel collaborative development of the IPT team, and analyses the definite mode and the application of this method.%根据航天型号研制的特点和 MBD 是唯一数据源的要求，探讨了模型成熟度以及MBD数据集的概念。对现有航天研制体制下如何构建IPT团队以及如何提高IPT团队的效率进行研究，最后将模型成熟度融入IPT团队的并行协同研制中，分析了这种方法的具体模式和应用。
LG Solid Oxide Fuel Cell (SOFC) Model Development
Haberman, Ben [LG Fuel Cell Systems Inc., North Canton, OH (United States); Martinez-Baca, Carlos [LG Fuel Cell Systems Inc., North Canton, OH (United States); Rush, Greg [LG Fuel Cell Systems Inc., North Canton, OH (United States)
2013-05-31
This report presents a summary of the work performed by LG Fuel Cell Systems Inc. during the project LG Solid Oxide Fuel Cell (SOFC) Model Development (DOE Award Number: DE-FE0000773) which commenced on October 1, 2009 and was completed on March 31, 2013. The aim of this project is for LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) to develop a multi-physics solid oxide fuel cell (SOFC) computer code (MPC) for performance calculations of the LGFCS fuel cell structure to support fuel cell product design and development. A summary of the initial stages of the project is provided which describes the MPC requirements that were developed and the selection of a candidate code, STAR-CCM+ (CD-adapco). This is followed by a detailed description of the subsequent work program including code enhancement and model verification and validation activities. Details of the code enhancements that were implemented to facilitate MPC SOFC simulations are provided along with a description of the models that were built using the MPC and validated against experimental data. The modeling work described in this report represents a level of calculation detail that has not been previously available within LGFCS.
A Photochemical Kinetic Model for Solid Dosage Forms.
Carvalho, Thiago C; La Cruz, Thomas E; Tabora, Jose E
2017-08-20
Photochemical kinetics models for pharmaceutical compounds in solution have been extensively investigated, but not in solid phase upon exposure to different light sources. The objective of this study was to develop a mathematical model to describe the solid state photodegradation of pharmaceutical powder materials under different area/volumetric scales and light exposure conditions. The model considered the previous formalism presented for photodegradation kinetics in solution phase with important elements applied to static powder material being irradiated with a polychromatic light source. The model also included the influence of optical phenomena (i.e. reflectance, scattering factors, etc.) by applying Beer-Lambert law to light attenuation, including effects of powder density. Drug substance and drug product intermediates (blends and tablet cores) were exposed to different light sources and intensities. The model reasonably predicted the photodegradation levels of powder beds of drug substance and drug product intermediates under white and yellow lights with intensities around 5 to 11 kLux. Importantly, the model estimates demonstrated that the reciprocity law for photoreactions was held. Further model evaluation showed that, due to light attenuation, the powder bed is in virtual darkness at cake depths greater than 500 μm. At 100 μm, the photodegradation of the investigated compound is expected to be close to 100% in 10 days under white fluorescent halophosphate light at 9.5 kLux. For tablets, defining the volume over exposed surface area ratio is more challenging. Nevertheless, the model can consider a bracket between worst and best cases to provide a reasonable photodegradation estimate. This tool can be significantly leveraged to simulate different light exposure scenarios while assessing photostability risk in order to define appropriate Control Strategy in manufacturing. Copyright © 2017. Published by Elsevier B.V.
Putnam, J. B.; Unataroiu, C. D.; Somers, J. T.
2014-01-01
The THOR anthropomorphic test device (ATD) has been developed and continuously improved by the National Highway Traffic Safety Administration to provide automotive manufacturers an advanced tool that can be used to assess the injury risk of vehicle occupants in crash tests. Recently, a series of modifications were completed to improve the biofidelity of THOR ATD [1]. The updated THOR Modification Kit (THOR-K) ATD was employed at Wright-Patterson Air Base in 22 impact tests in three configurations: vertical, lateral, and spinal [2]. Although a computational finite element (FE) model of the THOR had been previously developed [3], updates to the model were needed to incorporate the recent changes in the modification kit. The main goal of this study was to develop and validate a FE model of the THOR-K ATD. The CAD drawings of the THOR-K ATD were reviewed and FE models were developed for the updated parts. For example, the head-skin geometry was found to change significantly, so its model was re-meshed (Fig. 1a). A protocol was developed to calibrate each component identified as key to the kinematic and kinetic response of the THOR-K head/neck ATD FE model (Fig. 1b). The available ATD tests were divided in two groups: a) calibration tests where the unknown material parameters of deformable parts (e.g., head skin, pelvis foam) were optimized to match the data and b) validation tests where the model response was only compared with test data by calculating their score using CORrelation and Analysis (CORA) rating system. Finally, the whole ATD model was validated under horizontal-, vertical-, and lateral-loading conditions against data recorded in the Wright Patterson tests [2]. Overall, the final THOR-K ATD model developed in this study is shown to respond similarly to the ATD in all validation tests. This good performance indicates that the optimization performed during calibration by using the CORA score as objective function is not test specific. Therefore confidence is
Nehl, T. W.
1980-12-01
A discrete state space model of a power conditioner fed permanent magnet brushless dc motor for aerospace and electric vehicle applications is developed. The parameters which describe that machine portion of this model are derived from a two dimensional nonlinear magnetic field analysis using the finite element method. The model predicts the instantaneous mechanical and electrical behavior of a prototype electromechanical actuator for possible use on board the shuttle orbiter. The model is also used to simulate the instantaneous performance of an advanced electric vehicle propulsion unit. The results of the computer simulations are compared with experimental test data and excellent agreement between the two is found in all cases.
A Multistep Chaotic Model for Municipal Solid Waste Generation Prediction.
Song, Jingwei; He, Jiaying
2014-08-01
In this study, a univariate local chaotic model is proposed to make one-step and multistep forecasts for daily municipal solid waste (MSW) generation in Seattle, Washington. For MSW generation prediction with long history data, this forecasting model was created based on a nonlinear dynamic method called phase-space reconstruction. Compared with other nonlinear predictive models, such as artificial neural network (ANN) and partial least square-support vector machine (PLS-SVM), and a commonly used linear seasonal autoregressive integrated moving average (sARIMA) model, this method has demonstrated better prediction accuracy from 1-step ahead prediction to 14-step ahead prediction assessed by both mean absolute percentage error (MAPE) and root mean square error (RMSE). Max error, MAPE, and RMSE show that chaotic models were more reliable than the other three models. As chaotic models do not involve random walk, their performance does not vary while ANN and PLS-SVM make different forecasts in each trial. Moreover, this chaotic model was less time consuming than ANN and PLS-SVM models.
Space modeling with SolidWorks and NX
Duhovnik, Jože; Drešar, Primož
2015-01-01
Through a series of step-by-step tutorials and numerous hands-on exercises, this book aims to equip the reader with both a good understanding of the importance of space in the abstract world of engineers and the ability to create a model of a product in virtual space – a skill essential for any designer or engineer who needs to present ideas concerning a particular product within a professional environment. The exercises progress logically from the simple to the more complex; while SolidWorks or NX is the software used, the underlying philosophy is applicable to all modeling software. In each case, the explanation covers the entire procedure from the basic idea and production capabilities through to the real model; the conversion from 3D model to 2D manufacturing drawing is also clearly explained. Topics covered include modeling of prism, axisymmetric, symmetric, and sophisticated shapes; digitization of physical models using modeling software; creation of a CAD model starting from a physical model; free fo...
Model of spontaneous evaporating droplet on solid horizontal substrate
Dunin, S. Z.; Nagornov, O. V.; Trifonenkov, V. P.
2017-01-01
Free evaporation of sessile liquid non-isothermal drop on solid substrate is analyzed. Exact formulae for temperature and concentration fields are found out as functions of dimensionless parameters. The non-uniform temperature distribution at the drop surface creates the thermocapillar Marangonni forces that change their direction in the vicinity of stagnation points. Direction of the forces and disposition of the stagnation points are derived as function of contact angle and thermodynamic parameters of model. Conditions for the stagnation points to appear are found out. Moreover, maximal value of contact angle corresponding to presence of stagnation points in droplet is calculated as a function of the thermal conductivity ratio.
Forecasting municipal solid waste generation using artificial intelligence modelling approaches.
Abbasi, Maryam; El Hanandeh, Ali
2016-10-01
Municipal solid waste (MSW) management is a major concern to local governments to protect human health, the environment and to preserve natural resources. The design and operation of an effective MSW management system requires accurate estimation of future waste generation quantities. The main objective of this study was to develop a model for accurate forecasting of MSW generation that helps waste related organizations to better design and operate effective MSW management systems. Four intelligent system algorithms including support vector machine (SVM), adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN) and k-nearest neighbours (kNN) were tested for their ability to predict monthly waste generation in the Logan City Council region in Queensland, Australia. Results showed artificial intelligence models have good prediction performance and could be successfully applied to establish municipal solid waste forecasting models. Using machine learning algorithms can reliably predict monthly MSW generation by training with waste generation time series. In addition, results suggest that ANFIS system produced the most accurate forecasts of the peaks while kNN was successful in predicting the monthly averages of waste quantities. Based on the results, the total annual MSW generated in Logan City will reach 9.4×10(7)kg by 2020 while the peak monthly waste will reach 9.37×10(6)kg.
Davis JE, Eddy MJ, Sutton TM, Altomari TJ
2007-03-01
Solid modeling computer software systems provide for the design of three-dimensional solid models used in the design and analysis of physical components. The current state-of-the-art in solid modeling representation uses a boundary representation format in which geometry and topology are used to form three-dimensional boundaries of the solid. The geometry representation used in these systems is cubic B-spline curves and surfaces--a network of cubic B-spline functions in three-dimensional Cartesian coordinate space. Many Monte Carlo codes, however, use a geometry representation in which geometry units are specified by intersections and unions of half-spaces. This paper describes an algorithm for converting from a boundary representation to a half-space representation.
Aerospace engineering training: universities experience
Mertins Kseniya
2016-01-01
Full Text Available Contemporary professional working in aerospace engineering must have a set of soft and hard skills. The experience gained in universities shows that training of a competent professional is impossible without an employer involved in this process. The paper provides an analysis of missions, tasks and experience of aerospace professionals and identifies the present and future roles, missions and required skills of a highly qualified specialist in aerospace engineering. This analysis can be used to design a master’s program aiming at providing students with the required knowledge, know-how and attitudes needed to succeed as professionals in industrial companies.
E. V. Vysotskaya
2016-03-01
Full Text Available The "Introduction" describes topicality and importance of revealing the soil cover's disruption for a wide range of fields. It was shown that spectral brightness and colorimetric parameters of ground vegetation can be used for this task. However, a traditional scheme of data processing for remote sensing requires a long-term observations and can not always be applied, if quick decision-making is necessary or there is lack of information. Such cases require the use of special methods, one of which is a dynamic model developed with authors' participation based on the following basic relationships: (+,- (-, - (+, 0, (-, 0 (0,0. The section "Brief description of a dynamic model" describes the basic principles of dynamic systems used to solve the problem. Using above-mentioned relationships, the dynamics of a system consisting of several components is constructed and its main properties are listed. The main feature of this model is that the identification of structure and parameters of the dynamic system does not required sequential order of observations (as for models based on time series. This feature of the model enables for identifying the system's parameters of dynamics of the natural system to use information from a single picture taken from the spacecraft rather than long-term observations. The section "Materials and Methods" describes specific colorimetric parameters used to analyze the vegetation cover. The section "Obtained results" contains an example of the model's application to a satellite image for detecting the differences in two sites of a field with vegetation. One site is a recultivated area near the liquidated gas-oil well, another site is non-recultivated area at a considerable distance from the well (500-1000 m. The simulation results are described by eight signed graphs (4 graphs for each sites, whose structure allows to identify the system differences between the two cases. The section "Conclusions" summarizes the results of
Macro Level Modeling of a Tubular Solid Oxide Fuel Cell
Farshid Zabihian
2010-11-01
Full Text Available This paper presents a macro-level model of a solid oxide fuel cell (SOFC stack implemented in Aspen Plus® for the simulation of SOFC system. The model is 0-dimensional and accepts hydrocarbon fuels such as reformed natural gas, with user inputs of current density, fuel and air composition, flow rates, temperature, pressure, and fuel utilization factor. The model outputs the composition of the exhaust, work produced, heat available for the fuel reformer, and electrochemical properties of SOFC for model validation. It was developed considering the activation, concentration, and ohmic losses to be the main over-potentials within the SOFC, and mathematical expressions for these were chosen based on available studies in the literature. The model also considered the water shift reaction of CO and the methane reforming reaction. The model results were validated using experimental data from Siemens Westinghouse. The results showed that the model could capture the operating pressure and temperature dependency of the SOFC performance successfully in an operating range of 1–15 atm for pressure and 900 °C–1,000 °C for temperature. Furthermore, a sensitivity analysis was performed to identify the model constants and input parameters that impacted the over-potentials.
China To Boost Civil Aerospace Industrialization
无
2008-01-01
@@ The National Development and Reform Commission (NDRC) announced on January 30,2008 that it had approved the overall development planning of three national aerospace industrial bases.Building a civil aerospace industry base serves to optimize and integrate aerospace resources to further increase the potential for technological innovation and product R&D in China's aerospace industry.
Aerospace management techniques: Commercial and governmental applications
Milliken, J. G.; Morrison, E. J.
1971-01-01
A guidebook for managers and administrators is presented as a source of useful information on new management methods in business, industry, and government. The major topics discussed include: actual and potential applications of aerospace management techniques to commercial and governmental organizations; aerospace management techniques and their use within the aerospace sector; and the aerospace sector's application of innovative management techniques.
Demerdash, N. A. O.; Nehl, T. W.
1979-01-01
A description and user's guide of the computer program developed to simulate the dynamics of an electromechanical actuator for aerospace applications are presented. The effects of the stator phase currents on the permanent magnets of the rotor are examined. The voltage and current waveforms present in the power conditioner network during the motoring, regenerative braking, and plugging modes of operation are presented and discussed.
2009-11-04
need to keep the l if d i ti b tp asma un orm ur ng en re urs • We know that preheating will improve plasma uniformity • Sustaining plasma in a...0C sc arge p asmas n 2-a r an CxHy air mixtures, at P ~ 0.1 - 1 atm, T=300-800 K 500 600 700 800 P=40 torr, ν=40 kHz Air Air, model Outcome: kinetic...coup ng e ween p asma kinetics and flame chemistry is most important Laboratory for Advanced Fluid Dynamics and Combustion Research 0.0 0.3 0.6 0.9
Aerospace materials and material technologies
Wanhill, R
2017-01-01
This book is a comprehensive compilation of chapters on materials (both established and evolving) and material technologies that are important for aerospace systems. It considers aerospace materials in three Parts. Part I covers Metallic Materials (Mg, Al, Al-Li, Ti, aero steels, Ni, intermetallics, bronzes and Nb alloys); Part II deals with Composites (GLARE, PMCs, CMCs and Carbon based CMCs); and Part III considers Special Materials. This compilation has ensured that no important aerospace material system is ignored. Emphasis is laid in each chapter on the underlying scientific principles as well as basic and fundamental mechanisms leading to processing, characterization, property evaluation and applications. A considerable amount of materials data is compiled and presented in appendices at the end of the book. This book will be useful to students, researchers and professionals working in the domain of aerospace materials.
Automatically extracting sheet-metal features from solid model
刘志坚; 李建军; 王义林; 李材元; 肖祥芷
2004-01-01
With the development of modern industry,sheet-metal parts in mass production have been widely applied in mechanical,communication,electronics,and light industries in recent decades; but the advances in sheet-metal part design and manufacturing remain too slow compared with the increasing importance of sheet-metal parts in modern industry. This paper proposes a method for automatically extracting features from an arbitrary solid model of sheet-metal parts; whose characteristics are used for classification and graph-based representation of the sheet-metal features to extract the features embodied in a sheet-metal part. The extracting feature process can be divided for valid checking of the model geometry,feature matching,and feature relationship. Since the extracted features include abundant geometry and engineering information,they will be effective for downstream application such as feature rebuilding and stamping process planning.
Solid modeling and applications rapid prototyping, CAD and CAE theory
Um, Dugan
2016-01-01
The lessons in this fundamental text equip students with the theory of Computer Assisted Design (CAD), Computer Assisted Engineering (CAE), the essentials of Rapid Prototyping, as well as practical skills needed to apply this understanding in real world design and manufacturing settings. The book includes three main areas: CAD, CAE, and Rapid Prototyping, each enriched with numerous examples and exercises. In the CAD section, Professor Um outlines the basic concept of geometric modeling, Hermite and Bezier Spline curves theory, and 3-dimensional surface theories as well as rendering theory. The CAE section explores mesh generation theory, matrix notion for FEM, the stiffness method, and truss Equations. And in Rapid Prototyping, the author illustrates stereo lithographic theory and introduces popular modern RP technologies. Solid Modeling and Applications: Rapid Prototyping, CAD and CAE Theory is ideal for university students in various engineering disciplines as well as design engineers involved in product...
Life Cycle Costing Model for Solid Waste Management
Martinez-Sanchez, Veronica; Astrup, Thomas Fruergaard
2014-01-01
To ensure sustainability of solid waste management, there is a need for cost assessment models which are consistent with environmental and social assessments. However, there is a current lack of standardized terminology and methodology to evaluate economic performances and this complicates...... LCC, e.g. waste generator, waste operator and public finances and the perspective often defines the systemboundaries of the study, e.g. waste operators often focus on her/his own cost, i.e. technology based,whereas waste generators and public finances often focus on the entire waste system, i.......e. system based. Figure 1 illustrates the proposed modeling framework that distinguishes between: a) budget cost, b) externality costs and 3) transfers and defines unit costs of each technology (per ton of input waste). Unitcosts are afterwards combined with a mass balance to calculate the technology cost...
Mesoscale Modeling of Impact Compaction of Primitive Solar System Solids
Davison, Thomas M; Bland, Philip A
2016-01-01
We have developed a method for simulating the mesoscale compaction of early solar system solids in low velocity impact events, using the iSALE shock physics code. Chondrules are represented by nonporous disks, placed within a porous matrix. By simulating impacts into bimodal mixtures over a wide range of parameter space (including the chondrule-to-matrix ratio, the matrix porosity and composition and the impact velocity), we have shown how each of these parameters influences the shock processing of heterogeneous materials. The temperature after shock processing shows a strong dichotomy: matrix temperatures are elevated much higher than the chondrules, which remain largely cold. Chondrules can protect some matrix from shock compaction, with shadow regions in the lee side of chondrules exhibiting higher porosity that elsewhere in the matrix. Using the results from this mesoscale modelling, we show how the $\\varepsilon-\\alpha$ porous compaction model parameters depend on initial bulk porosity. We also show that ...
Automatically extracting sheet-metal features from solid model
刘志坚; 李建军; 王义林; 李材元; 肖祥芷
2004-01-01
With the development of modern industry, sheet-metal parts in mass production have been widely applied in mechanical, communication, electronics, and light industries in recent decades; but the advances in sheet-metal part design and manufacturing remain too slow compared with the increasing importance of sheet-metal parts in modern industry. This paper proposes a method for automatically extracting features from an arbitrary solid model of sheet-metal parts; whose characteristics are used for classification and graph-based representation of the sheet-metal features to extract the features embodied in a sheet-metal part. The extracting feature process can be divided for valid checking of the model geometry, feature matching, and feature relationship. Since the extracted features include abundant geometry and engineering information, they will be effective for downstream application such as feature rebuilding and stamping process planning.
GISCOD: general integrated solid waste co-digestion model.
Zaher, Usama; Li, Rongping; Jeppsson, Ulf; Steyer, Jean-Philippe; Chen, Shulin
2009-06-01
This paper views waste as a resource and anaerobic digestion (AD) as an established biological process for waste treatment, methane production and energy generation. A powerful simulation tool was developed for the optimization and the assessment of co-digestion of any combination of solid waste streams. Optimization was aimed to determine the optimal ratio between different waste streams and hydraulic retention time by changing the digester feed rates to maximize the biogas production rate. Different model nodes based on the ADM1 were integrated and implemented on the Matlab-Simulink simulation platform. Transformer model nodes were developed to generate detailed input for ADM1, estimating the particulate waste fractions of carbohydrates, proteins, lipids and inerts. Hydrolysis nodes were modeled separately for each waste stream. The fluxes from the hydrolysis nodes were combined and generated a detailed input vector to the ADM1. The integrated model was applied to a co-digestion case study of diluted dairy manure and kitchen wastes. The integrated model demonstrated reliable results in terms of calibration and optimization of this case study. The hydrolysis kinetics were calibrated for each waste fraction, and led to accurate simulation results of the process and prediction of the biogas production. The optimization simulated 200,000 days of virtual experimental time in 8 h and determined the feedstock ratio and retention time to set the digester operation for maximum biogas production rate.
Model Order Reduction for Fluid Dynamics with Moving Solid Boundary
Gao, Haotian; Wei, Mingjun
2016-11-01
We extended the application of POD-Galerkin projection for model order reduction from usual fixed-domain problems to more general fluid-solid systems when moving boundary/interface is involved. The idea is similar to numerical simulation approaches using embedded forcing terms to represent boundary motion and domain change. However, such a modified approach will not get away with the unsteadiness of boundary terms which appear as time-dependent coefficients in the new Galerkin model. These coefficients need to be pre-computed for prescribed motion, or worse, to be computed at each time step for non-prescribed motion. The extra computational cost gets expensive in some cases and eventually undermines the value of using reduced-order models. One solution is to decompose the moving boundary/domain to orthogonal modes and derive another low-order model with fixed coefficients for boundary motion. Further study shows that the most expensive integrations resulted from the unsteady motion (in both original and domain-decomposition approaches) have almost negligible impact on the overall dynamics. Dropping these expensive terms reduces the computation cost by at least one order while no obvious effect on model accuracy is noticed. Supported by ARL.
Dynamic spreading of nanofluids on solids part II: modeling.
Liu, Kuan-Liang; Kondiparty, Kirtiprakash; Nikolov, Alex D; Wasan, Darsh
2012-11-27
Recent studies on the spreading phenomena of liquid dispersions of nanoparticles (nanofluids) have revealed that the self-layering and two-dimensional structuring of nanoparticles in the three-phase contact region exert structural disjoining pressure, which drives the spreading of nanofluids by forming a continuous wedge film between the liquid (e.g., oil) and solid surface. Motivated by the practical applications of the phenomenon and experimental results reported in Part I of this two-part series, we thoroughly investigated the spreading dynamics of nanofluids against an oil drop on a solid surface. With the Laplace equation as a starting point, the spreading process is modeled by Navier-Stokes equations through the lubrication approach, which considers the structural disjoining pressure, gravity, and van der Waals force. The temporal interface profile and advancing inner contact line velocity of nanofluidic films are analyzed through varying the effective nanoparticle concentration, the outer contact angle, the effective nanoparticle size, and capillary pressure. It is found that a fast and spontaneous advance of the inner contact line movement can be obtained by increasing the nanoparticle concentration, decreasing the nanoparticle size, and/or decreasing the interfacial tension. Once the nanofluidic film is formed, the advancing inner contact line movement reaches a constant velocity, which is independent of the outer contact angle if the interfacial tension is held constant.
石柱; 何新责
2000-01-01
In this paper, the basic concepts related to sottware life-cycle models are presented first, the four typical life-cycle models including waterfall model, incremental model, evolutionary model and packagebased model, which have been successfully used in aerospace software development in China and abroad, are discussed. Finally, the guidelines on selecting an appropriate life-cycle model for a specific aerospace software project are proposed.%文中首先阐述有关生存周期模型的基本概念，简要介绍4个已在国内外航天界得到成功应用的典型生存周期模型：瀑布模型、增量模型、进化模型和基于软件包的生存周期模型，分别给出了这4个生存周期模型的优点、缺点、适用情况以及各生存周期阶段的主要产品和里程碑评审，最后给出选择航天型号软件生存周期模型的基本原则。
2012-08-01
the point of phase change is reached. Solid-phase exothermic reactions may occur in some propellant ingredients (such as AP [9] or ADN [4]) leading...M.L. Gross. Two-dimensional modeling of AP/HTPB utilizing a vorticity formula- tion and one-dimensional modeling of AP and ADN . PhD thesis, Brigham
State-of-the-Art Solid Waste Management Life-Cycle Modeling Workshop
Damgaard, Anders; Levis, James W.
There are many alternatives for the management of solid waste including recycling, biological treatment, thermal treatment and landfill disposal. In many cases, solid waste management systems include the use of several of these processes. Solid waste life-cycle assessment models are often used...... to evaluate the environmental consequences of various waste management strategies. The foundation of every life-cycle model is the development and use of process models to estimate the emissions from solid waste unit processes. The objective of this workshop is to describe life-cycle modeling of the solid...... waste processes and systems. The workshop will begin with an introduction to solid waste life-cycle modeling and available models, which will be followed by sessions on life-cycle process modeling for individual processes (e.g., landfills, biological treatment, and thermal treatment). The first part...
Automatic paper sliceform design from 3D solid models.
Le-Nguyen, Tuong-Vu; Low, Kok-Lim; Ruiz, Conrado; Le, Sang N
2013-11-01
A paper sliceform or lattice-style pop-up is a form of papercraft that uses two sets of parallel paper patches slotted together to make a foldable structure. The structure can be folded flat, as well as fully opened (popped-up) to make the two sets of patches orthogonal to each other. Automatic design of paper sliceforms is still not supported by existing computational models and remains a challenge. We propose novel geometric formulations of valid paper sliceform designs that consider the stability, flat-foldability and physical realizability of the designs. Based on a set of sufficient construction conditions, we also present an automatic algorithm for generating valid sliceform designs that closely depict the given 3D solid models. By approximating the input models using a set of generalized cylinders, our method significantly reduces the search space for stable and flat-foldable sliceforms. To ensure the physical realizability of the designs, the algorithm automatically generates slots or slits on the patches such that no two cycles embedded in two different patches are interlocking each other. This guarantees local pairwise assembility between patches, which is empirically shown to lead to global assembility. Our method has been demonstrated on a number of example models, and the output designs have been successfully made into real paper sliceforms.
Modeling Degradation in Solid Oxide Electrolysis Cells - Volume II
Manohar Motwani
2011-09-01
Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic non-equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential,, within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, non-equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.
Multiscale approach to modeling intrinsic dissipation in solids
Kunal, K.; Aluru, N. R.
2016-08-01
In this paper, we develop a multiscale approach to model intrinsic dissipation under high frequency of vibrations in solids. For vibrations with a timescale comparable to the phonon relaxation time, the local phonon distribution deviates from the equilibrium distribution. We extend the quasiharmonic (QHM) method to describe the dynamics under such a condition. The local deviation from the equilibrium state is characterized using a nonequilibrium stress tensor. A constitutive relation for the time evolution of the stress component is obtained. We then parametrize the evolution equation using the QHM method and a stochastic sampling approach. The stress relaxation dynamics is obtained using mode Langevin dynamics. Methods to obtain the input variables for the Langevin dynamics are discussed. The proposed methodology is used to obtain the dissipation rate Edissip for different cases. Frequency and size effect on Edissip are studied. The results are compared with those obtained using nonequilibrium molecular dynamics (MD).
A Model of Solid Waste Management Based Multilateral Co-Operation in Semi-Urban Community
Kanchanabhandhu, Chanchai; Woraphong, Seree
2016-01-01
The purpose of this research was to construct a model of solid waste management based on multilateral cooperation in semi-urban community. Its specific objectives were to 1) study the solid waste situation and involvement of community in the solid waste management in Wangtaku Sub-district, Muang District, Nakhon Pathom Province; 2) construct a…
Solid charged-core model of ball lightning
D. B. Muldrew
2010-01-01
Full Text Available In this study, ball lightning (BL is assumed to have a solid, positively-charged core. According to this underlying assumption, the core is surrounded by a thin electron layer with a charge nearly equal in magnitude to that of the core. A vacuum exists between the core and the electron layer containing an intense electromagnetic (EM field which is reflected and guided by the electron layer. The microwave EM field applies a ponderomotive force (radiation pressure to the electrons preventing them from falling into the core. The energetic electrons ionize the air next to the electron layer forming a neutral plasma layer. The electric-field distributions and their associated frequencies in the ball are determined by applying boundary conditions to a differential equation given by Stratton (1941. It is then shown that the electron and plasma layers are sufficiently thick and dense to completely trap and guide the EM field. This model of BL is exceptional in that it can explain all or nearly all of the peculiar characteristics of BL. The ES energy associated with the core charge can be extremely large which can explain the observations that occasionally BL contains enormous energy. The mass of the core prevents the BL from rising like a helium-filled balloon – a problem with most plasma and burning-gas models. The positively charged core keeps the negatively charged electron layer from diffusing away, i.e. it holds the ball together; other models do not have a mechanism to do this. The high electrical charges on the core and in the electron layer explains why some people have been electrocuted by BL. Experiments indicate that BL radiates microwaves upon exploding and this is consistent with the model. The fact that this novel model of BL can explain these and other observations is strong evidence that the model should be taken seriously.
Development of a solid propellant viscoelastic dynamic model
Hufferd, W. L.; Fitzgerald, J. E.
1976-01-01
The results of a one year study to develop a dynamic response model for the Space Shuttle Solid Rocket Motor (SRM) propellant are presented. An extensive literature survey was conducted, from which it was concluded that the only significant variables affecting the dynamic response of the SRM propellant are temperature and frequency. Based on this study, and experimental data on propellants related to the SRM propellant, a dynamic constitutive model was developed in the form of a simple power law with temperature incorporated in the form of a modified power law. A computer program was generated which performs a least-squares curve-fit of laboratory data to determine the model parameters and it calculates dynamic moduli at any desired temperature and frequency. Additional studies investigated dynamic scaling laws and the extent of coupling between the SRM propellant and motor cases. It was found, in agreement with other investigations, that the propellant provides all of the mass and damping characteristics whereas the case provides all of the stiffness.
Bioengineered models of solid human tumors for cancer research
Marturano-Kruik, Alessandro; Villasante, Aranzazu; Vunjak-Novakovic, Gordana
2016-01-01
Summary The lack of controllable in vitro models that can recapitulate the features of solid tumors such as Ewing’s sarcoma limits our understanding of the tumor initiation and progression and impedes the development of new therapies. Cancer research still relies of the use of simple cell culture, tumor spheroids, and small animals. Tissue-engineered tumor models are now being grown in vitro to mimic the actual tumors in patients. Recently, we have established a new protocol for bioengineering the Ewing’s sarcoma, by infusing tumor cell aggregates into the human bone engineered from the patient’s mesenchymal stem cells. The bone niche allows crosstalk between the tumor cells, osteoblasts and supporting cells of the bone, extracellular matrix and the tissue microenvironment. The bioreactor platform used in these experiments also allows the implementation of physiologically relevant mechanical signals. Here, we describe a method to build an in vitro model of Ewing’s sarcoma that mimics the key properties of the native tumor and provides the tissue context and physical regulatory signals. PMID:27115504
PHYSICAL MODEL FOR THE ENGINEERING ANALYSIS OF THE THERMOELASTICLTY OF SOLID BODIES
无
2000-01-01
The thermal behaviour of the solids under elastic deformations is analysed in order to obtain a model which combines the molecular dynamics results with the global thermal behaviour of the solids under elastic t ransformations.The result obtained consists of the introduction of the thermal behaviour in the ParrinelloRahman model,obtaining the thermal molecular dynamic model useful in the analysis of the thermoelastic behaviour of solids.
2013-08-06
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Airplanes AGENCY... Certificate Previously Held by Israel Aircraft Industries, Ltd.) Model Gulfstream 100 airplanes, and Model...: 2013-14-10 Gulfstream Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries,...
Multi-Physics Coupling Approaches for Aerospace Numerical Simulations.
Errera, M.; Dugeai, A.; Girodroux-Lavigne, P.; Garaud, J.D.; Poinot, M.; Cerqueira, S.; Chaineray, G.
2011-01-01
International audience; The purpose of this paper is to present coupling strategies for aerospace numerical calculations. In the first part, the basic approach used relies on the partitioned coupling of a finite-volume Navier-Stokes solver and a finite-element solid code. These two separate and independent simulation tools carry out exchanges via a coupling library. Two different applications illustrate the capabilities of this coupling method. The main advantage of this approach is to benefi...
Mathematical-statistical models of generated hazardous hospital solid waste.
Awad, A R; Obeidat, M; Al-Shareef, M
2004-01-01
This research work was carried out under the assumption that wastes generated from hospitals in Irbid, Jordan were hazardous. The hazardous and non-hazardous wastes generated from the different divisions in the three hospitals under consideration were not separated during collection process. Three hospitals, Princess Basma hospital (public), Princess Bade'ah hospital (teaching), and Ibn Al-Nafis hospital (private) in Irbid were selected for this study. The research work took into account the amounts of solid waste accumulated from each division and also determined the total amount generated from each hospital. The generation rates were determined (kilogram per patient, per day; kilogram per bed, per day) for the three hospitals. These generation rates were compared with similar hospitals in Europe. The evaluation suggested that the current situation regarding the management of these wastes in the three studied hospitals needs revision as these hospitals do not follow methods of waste disposals that would reduce risk to human health and the environment practiced in developed countries. Statistical analysis was carried out to develop models for the prediction of the quantity of waste generated at each hospital (public, teaching, private). In these models number of patients, beds, and type of hospital were revealed to be significant factors on quantity of waste generated. Multiple regressions were also used to estimate the quantities of wastes generated from similar divisions in the three hospitals (surgery, internal diseases, and maternity).
Cao, M; Monson, P A
2009-10-22
We present a study of the phase behavior for models of n-alkanes with chain lengths up to C(21) based on hard sphere united atom models of methyl and methylene groups, with fixed bond lengths and C-C-C bond angles. We extend earlier work on such models of shorter alkanes by allowing for gauche conformations in the chains. We focus particularly on the orientational order about the chain axes in the solid phase near the melting point, and our model shows how the loss of this orientational order leads to the formation of rotator phases. We have made extensive calculations of the thermodynamic properties of the models as well as order parameters for tracking the degree of orientational order around the chain axis. Depending on the chain length and whether the carbon number is even or odd, the model exhibits both a rotator phase and a more orientationally ordered solid phase in addition to the fluid phase. Our results indicate that the transition between the two solid phases is first-order with a small density change. The results are qualitatively similar to those seen experimentally and show that rotator phases can appear in models of alkanes without explicit treatment of attractive forces or explicit treatment of the hydrogen atoms in the chains.
Challenges in aerospace medicine education.
Grenon, S Marlene; Saary, Joan
2011-11-01
Aerospace medicine training and research represents a dream for many and a challenge for most. In Canada, although some opportunities exist for the pursuit of education and research in the aerospace medicine field, they are limited despite the importance of this field for enabling safe human space exploration. In this commentary, we aim to identify some of the challenges facing individuals wishing to get involved in the field as well as the causal factors for these challenges. We also explore strategies to mitigate against these.
Investigation of binary solid phases by calorimetry and kinetic modelling
Matovic, M.
2007-01-01
The traditional methods for the determination of liquid-solid phase diagrams are based on the assumption that the overall equilibrium is established between the phases. However, the result of the crystallization of a liquid mixture will typically be a non-equilibrium or metastable state of the solid
Modelling biogas production of solid waste: application of the BGP model to a synthetic landfill
Rodrigo-Ilarri, Javier; Segura-Sobrino, Francisco
2013-04-01
Production of biogas as a result of the decomposition of organic matter included on solid waste landfills is still an issue to be understood. Reports on this matter are rarely included on the engineering construction projects of solid waste landfills despite it can be an issue of critical importance while operating the landfill and after its closure. This paper presents an application of BGP (Bio-Gas-Production) model to a synthetic landfill. The evolution in time of the concentrations of the different chemical compounds of biogas is studied. Results obtained show the impact on the air quality of different management alternatives which are usually performed in real landfills.
Modeling transportation of suspended solids in Zhujiang River estuary, South China
CHEN Xiaohong; CHEN Yongqin; LAI Guoyou
2005-01-01
A three-dimensional transportation model for suspended solids (SS) in Zhujiang (Pearl) River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using hourly measured data of sediment contents during 25-26, July 1999. The results showed that modeled contents matched well with measured ones and that the modeled top layer distribution agreed with the remotely sensed image of suspended solids in summer. The modeled results showed clearly the layers of suspended solids in depth, with larger sediment contents in lower layers though in the interface between salt water and freshwater the lowest contents appeared in middle layer. In overall, the suspended solids inflow from 8 rivers, transport southwestward, and carried by strong coastal flow in Zhujiang River estuary. Contours of sediment contents in the estuary spread further to the open sea during ebb tide rather than flood tide which reflects that the suspended solids in the estuary are land sourced.
Modeling plasma plumes generated from laser solid interactions
Wilks, Scott C.; Higginson, D. P.; Link, A. J.; Park, H.-S.; Ping, Y.; Rinderknecht, H. G.; Ross, J. S.; Orban, C.; Hua, R.
2016-10-01
Laser pulses interacting with solid targets sitting in a vacuum form the basis for a large class of High Energy Density physics experiments. The resulting hydrodynamical evolution of the target during and after this interaction can be modeled using myriad techniques. These techniques range from pure particle-in-cell (PIC) to pure radiation-hydrodynamics, and include a large number of hybrid techniques in between. The particular method employed depends predominately on laser intensity. We compare and contrast several methods relevant for a large range of laser intensities (from Iλ2 1 ×1012W . μm2 /cm2 to Iλ2 1 ×1019W . μm2 /cm2) and energies (from E 100 mJ to E 100 kJ .) Density, temperature, and velocity profiles are benchmarked against recent experimental data. These experimental data include proton radiographs, time resolved x-ray images, and neutron yield and spectra. Methods to self-consistently handle backscatter and detailed energy deposition will also be discussed. LLNL-ABS-697767. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Aerospace Training. Washington's Community and Technical Colleges
Washington State Board for Community and Technical Colleges, 2014
2014-01-01
Aerospace is an economic powerhouse that generates jobs and fuels our economy. Washington's community and technical colleges produce the world-class employees needed to keep it that way. With about 1,250 aerospace-related firms employing more than 94,000 workers, Washington has the largest concentration of aerospace expertise in the nation. To…
Solid-Liquid equilibrium of n-alkanes using the Chain Delta Lattice Parameter model
Coutinho, João A.P.; Andersen, Simon Ivar; Stenby, Erling Halfdan
1996-01-01
The formation of a solid phase in liquid mixtures with large paraffinic molecules is a phenomenon of interest in the petroleum, pharmaceutical, and biotechnological industries among onters. Efforts to model the solid-liquid equilibrium in these systems have been mainly empirical and with different...... degrees of success.An attempt to describe the equilibrium between the high temperature form of a paraffinic solid solution, commonly known as rotator phase, and the liquid phase is performed. The Chain Delta Lattice Parameter model (CDLP) is developed allowing a successful description of the solid-liquid...... equilibrium of n-alkanes ranging from n-C_20 to n-C_40.The model is further modified to achieve a more correct temperature dependence because it severely underestimates the excess enthalpy. It is shown that the ratio of excess enthalpy and entropy for n-alkane solid solutions, as happens for other solid...
Modelling elasticity in solids using active cubes - application to simulated operations
Bro-Nielsen, Morten
1995-01-01
The paper describes an approach to elastic modelling of human tissue based on the use of 3D solid active models-active cubes (M. Bro-Nielsen, 1994)-and a shape description based on the metric tensor in a solid. Active cubes are used because they provide a natural parameterization of the surface a...
Aerospace applications of magnetic bearings
Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard
1994-01-01
Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.
Ceramic composites: Enabling aerospace materials
Levine, S. R.
1992-01-01
Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.
Modeling washoff of total suspended solids in the tropics.
Le, S H; Chua, L H C; Irvine, K N; Eikaas, H S
2017-09-15
Washoff behavior in the tropics is expected to behave differently from temperate areas due to differences in rainfall characteristics. In this study, rainfall, runoff and total suspended solids (TSS) were monitored from 9 catchments distinguished by different types of land use, in Singapore. The catchments ranged in size from 5.7ha to 85.2ha. Over 120 rain events were studied and more than 1000 storm samples were collected and analyzed. Monte Carlo analysis was applied to obtain the best fit values of the washoff model parameters consisting the washoff coefficient c3, washoff exponent c4 and initial mass on surface Bini. The exponent c4 was found to be approximately unity for all the events monitored, in agreement with other studies. The values of c3 and Bini were found to vary between events. Among all the rainfall and runoff characteristics studied, rainfall depth of the current event (d) was found to be the single parameter that significantly influenced the values of c3 and Bini. Contrary to expectations, Bini did not correlate well with antecedent dry period or with rainfall depth of the prior storm event. The results show that the common modeling practice where Bini is assumed to vary with antecedent dry period and previous rainfall depth should be reassessed when applied to catchments in the tropics. ANCOVA analysis showed that land use was not significant, but rather the variation of c3 and Bini with d was found to correlate well with the catchment area. Copyright © 2017 Elsevier Ltd. All rights reserved.
Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.
1994-01-01
The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DOD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical communications practices of U.S. aerospace engineers and scientists affiliated with, not necessarily belonging to, the Society of Manufacturing Engineers (SME).
Domestic applications for aerospace waste and water management technologies
Disanto, F.; Murray, R. W.
1972-01-01
Some of the aerospace developments in solid waste disposal and water purification, which are applicable to specific domestic problems are explored. Also provided is an overview of the management techniques used in defining the need, in utilizing the available tools, and in synthesizing a solution. Specifically, several water recovery processes will be compared for domestic applicability. Examples are filtration, distillation, catalytic oxidation, reverse osmosis, and electrodialysis. Solid disposal methods will be discussed, including chemical treatment, drying, incineration, and wet oxidation. The latest developments in reducing household water requirements and some concepts for reusing water will be outlined.
Investigating conceptual models for physical property couplings in solid solution models of cement
Benbow, Steven; Watson, Claire; Savage, David [Quintesssa Ltd., Henley-on-Thames (United Kingdom)
2005-11-15
The long-term behaviour of cementitious engineered barriers is an important process to consider when modelling the migration of radionuclides from a geological repository for nuclear waste. The modelling of cement is complicated by the fact that the cement is dominated by the behaviour of calcium silicate hydrate (CSH) gel which is a complex solid exhibiting incongruent dissolution behaviour. In this report, we have demonstrated the implementation of a solid-solution CSH gel model within a geochemical transport modelling framework using the Raiden computer code to investigate cement/concrete-groundwater interactions. The modelling conducted here shows that it is possible to couple various conceptual models for the evolution of physical properties of concrete with a solid solution model for cement degradation in a fully coupled geochemical transport model to describe the interaction of cement/concrete engineered barriers with groundwater. The results show that changes to the conceptual models and flow rates can give rise to very different evolutions. Most simulations were carried out at a reduced 'experimental' scale rather than full repository scale. The work has shown the possibility to investigate also the changing physical properties of degrading cement. To further develop the model more emphasis is needed on kinetics and the detailed development of a nearly clogged pore space. Modelling of the full repository scale could be another way forward to understand the behaviour of degrading concrete. A general conclusion is that the combined effects of chemical evolution and physical degradation should be analysed in performance assessments of cementitious repositories. Moreover, the project results will be used as one basis in coming reviews of SKB's safety assessments of repositories for spent fuel and low-and intermediate level waste.
Modeling the solid-liquid phase transition in saturated triglycerides
Pink, David A.; Hanna, Charles B.; Sandt, Christophe; MacDonald, Adam J.; MacEachern, Ronald; Corkery, Robert; Rousseau, Dérick
2010-02-01
We investigated theoretically two competing published scenarios for the melting transition of the triglyceride trilaurin (TL): those of (1) Corkery et al. [Langmuir 23, 7241 (2007)], in which the average state of each TL molecule in the liquid phase is a discotic "Y" conformer whose three chains are dynamically twisted, with an average angle of ˜120° between them, and those of (2) Cebula et al. [J. Am. Oil Chem. Soc. 69, 130 (1992)], in which the liquid-state conformation of the TL molecule in the liquid phase is a nematic h∗-conformer whose three chains are in a modified "chair" conformation. We developed two competing models for the two scenarios, in which TL molecules are in a nematic compact-chair (or "h") conformation, with extended, possibly all-trans, chains at low-temperatures, and in either a Y conformation or an h∗ conformation in the liquid state at temperatures higher than the phase-transition temperature, T∗=319 K. We defined an h-Y model as a realization of the proposal of Corkery et al. [Langmuir 23, 7241 (2007)], and explored its predictions by mapping it onto an Ising model in a temperature-dependent field, performing a mean-field approximation, and calculating the transition enthalpy ΔH. We found that the most plausible realization of the h-Y model, as applied to the solid-liquid phase transition in TL, and likely to all saturated triglycerides, gave a value of ΔH in reasonable agreement with the experiment. We then defined an alternative h-h∗ model as a realization of the proposal of Cebula et al. [J. Am. Oil Chem. Soc. 69, 130 (1992)], in which the liquid phase exhibits an average symmetry breaking similar to an h conformation, but with twisted chains, to see whether it could describe the TL phase transition. The h-h∗ model gave a value of ΔH that was too small by a factor of ˜3-4. We also predicted the temperature dependence of the 1132 cm-1 Raman band for both models, and performed measurements of the ratios of three TL Raman
2011-07-14
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Model Galaxy, Gulfstream... AD. Discussion The Civil Aviation Authority (CAA), which is the aviation authority for Israel, has...: Gulfstream Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.): Docket No...
2011-12-19
...-005-AD; Amendment 39-16890; AD 2011-06-06 R1] RIN 2120-AA64 Airworthiness Directives; Eclipse... directive (AD) that applies to all Eclipse Aerospace, Inc. Model EA500 airplanes equipped with Pratt...: 2011-06-06 R1 Eclipse Aerospace, Inc.: Amendment 39-16890; Docket No. FAA-2011-0199;...
2012-05-31
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Airplanes AGENCY... previously held by Israel Aircraft Industries, Ltd.) Model Galaxy and Gulfstream 200 airplanes. This proposed.... 39.13 by adding the following new AD: Gulfstream Aerospace LP (Type Certificate previously held...
2013-02-19
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Airplanes AGENCY... Previously Held by Israel Aircraft Industries, Ltd.) Model Gulfstream G150 airplanes. This AD was prompted by...: 2013-03-23 Gulfstream Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries,...
2011-11-10
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Airplanes AGENCY... previously held by Israel Aircraft Industries, Ltd.) Model Galaxy and Gulfstream G150 airplanes; and...: 2011-23-07 Gulfstream Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries,...
2012-07-30
... Aerospace LP (Type Certificate Previously Held by Israel Aircraft Industries, Ltd.) Airplanes AGENCY... previously held by Israel Aircraft Industries, Ltd.) Model Astra SPX, 1125 Westwind Astra, and Gulfstream 100... new AD: 2012-15-06 Gulfstream Aerospace LP (Type Certificate Previously Held by Israel...
Modeling of urban solid waste management system: the case of Dhaka city.
Sufian, M A; Bala, B K
2007-01-01
This paper presents a system dynamics computer model to predict solid waste generation, collection capacity and electricity generation from solid waste and to assess the needs for waste management of the urban city of Dhaka, Bangladesh. Simulated results show that solid waste generation, collection capacity and electricity generation potential from solid waste increase with time. Population, uncleared waste, untreated waste, composite index and public concern are projected to increase with time for Dhaka city. Simulated results also show that increasing the budget for collection capacity alone does not improve environmental quality; rather an increased budget is required for both collection and treatment of solid wastes of Dhaka city. Finally, this model can be used as a computer laboratory for urban solid waste management (USWM) policy analysis.
Modeling of Roller Bracket on SolidWorks%基于SolidWorks的上托辊架三维建模
邵娜
2015-01-01
介绍一种利用SolidWorks软件中的焊件设计模块对带式输送机托辊架进行建模的方法，该方法操作简单、快捷。通过对上托辊架的三维建模以及虚拟装配，可以很直观地检查出设计中的错误，提高设计效率。%Introduces a method of roller bracket model of belt conveyor by using weldment design module of SolidWorks software, the method is simple and fast. Through the roller frame 3D modeling and virtual assembly, can be very intuitive to check out the design errors and improve design efficiency.
Modeling and simulation of liquid diffusion through a porous finitely elastic solid
Zhao, Qiangsheng
2013-01-29
A new theory is proposed for the continuum modeling of liquid flow through a porous elastic solid. The solid and the voids are assumed to jointly constitute the macroscopic solid phase, while the liquid volume fraction is included as a separate state variable. A finite element implementation is employed to assess the predictive capacity of the proposed theory, with particular emphasis on the mechanical response of Nafion® membranes to the flow of water. © 2013 Springer-Verlag Berlin Heidelberg.
The need for the solid modelling of structure in the archaeology of buildings
Robert Daniels
1997-03-01
Full Text Available Three-dimensional modelling is an attempt to represent the world in three dimensions, simplifying through deliberate assumptions. In archaeology, this has developed as an extension of the traditional use of three-dimensional drawings to help present and record data. The debate in the archaeological literature over whether surface or solid modellers should be used is one based on the premise that the purpose of three-dimensional modelling is data visualisation. This concentration on perception modelling has been at the expense of research on the modelling of structure. Surface and Solid Modellers are introduced and defined. I argue that developments in modelling software mean that there is no longer a clear distinction between the two types of software along application lines. We should think of models in terms of their applications rather than the software which generates them. Although data visualisation (including virtual reality is an important part of three-dimensional modelling, I argue that it should be explicitly divorced from the related field of photo-realism at a research level. Perception modelling can be performed by surface or solid modellers. Modelling structure is better performed with a solid modeller, if we wish to be as explicit as possible in our modelling. A structural model can be used as a spatial database. If we wish to ask questions about the physical properties of a structure, then we must use solid modellers. In addition to the engineering properties of structures, solid modellers can also be used to answer questions about the economics of construction. For historical reasons, the construction industry has preferred to use surface modellers, but I argue for the advantages of solid modelling in the archaeological study of construction.
João Henrique Lopes Guerra
2011-01-01
Full Text Available A ampliação das alianças estratégicas na indústria aeronáutica mostra uma clara opção dos fabricantes de avião por um modelo de integração de sistemas em que eles concentram o seu foco em atividades relacionadas às suas competências essenciais. Apesar da importância desta indústria e embora os principais fabricantes de avião do mundo estejam adotando este modelo, a literatura sobre este tema ainda é escassa e, mesmo a existente, encontra-se muito fragmentada. Este trabalho, qualitativo e de cunho teórico-conceitual, aproveita a literatura disponível e observa a movimentação dos principais fabricantes de avião do mundo para identificar e compreender os fatores que os têm motivado a adotar este modelo. Os seguintes fatores foram identificados: o interesse em tecnologias e empresas especializadas, os acordos de offset e as grandes barreiras e riscos existentes na indústria aeronáutica. Como decorrência do modelo de integração de sistemas, a indústria aeronáutica sofre atualmente uma agressiva desintegração vertical.The increase in the number of strategic alliances in the aerospace industry shows a clear option of the aircraft manufacturers for a system integration model in which they can concentrate their focus on activities related to their core competences. Despite the importance of this industry and the fact that the major aircraft manufacturers in the world have adopted this model, the literature on this subject is rather scarce and fragmented. A qualitative and theoretical-conceptual research was carried out making use of the available literature and investigating the movement of the major aircraft manufacturers in the world to identify and understand the factors that have been motivating them to adopt this model. The following factors were identified: the interest in specialized technologies and companies, the offset agreements, and the great barriers and risks in the aerospace industry. Due to the system
Numerical modelling of biomass combustion: Solid conversion processes in a fixed bed furnace
Karim, Md. Rezwanul; Naser, Jamal
2017-06-01
Increasing demand for energy and rising concerns over global warming has urged the use of renewable energy sources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions. Combustion of solid biomass is a complex phenomenon due to its large varieties and physical structures. Among various systems, fixed bed combustion is the most commonly used technique for thermal conversion of solid biomass. But inadequate knowledge on complex solid conversion processes has limited the development of such combustion system. Numerical modelling of this combustion system has some advantages over experimental analysis. Many important system parameters (e.g. temperature, density, solid fraction) can be estimated inside the entire domain under different working conditions. In this work, a complete numerical model is used for solid conversion processes of biomass combustion in a fixed bed furnace. The combustion system is divided in to solid and gas phase. This model includes several sub models to characterize the solid phase of the combustion with several variables. User defined subroutines are used to introduce solid phase variables in commercial CFD code. Gas phase of combustion is resolved using built-in module of CFD code. Heat transfer model is modified to predict the temperature of solid and gas phases with special radiation heat transfer solution for considering the high absorptivity of the medium. Considering all solid conversion processes the solid phase variables are evaluated. Results obtained are discussed with reference from an experimental burner.
Space Station Freedom - A resource for aerospace education
Brown, Robert W.
1988-01-01
The role of the International Space Station in future U.S. aerospace education efforts is discussed from a NASA perspective. The overall design concept and scientific and technological goals of the Space Station are reviewed, and particular attention is given to education projects such as the Davis Planetarium Student Space Station, the Starship McCullough, the Space Habitat, the working Space Station model in Austin, TX, the Challenger Center for Space Life Education, Space M+A+X, and the Space Science Student Involvement Program. Also examined are learning-theory aspects of aerospace education: child vs adult learners, educational objectives, teaching methods, and instructional materials.
Inspection tools for aerospace critical surfaces
Workman, Gary L.; Thompson, G. W.; Nerren, Billy H.; Burns, H. Dewitt, Jr.
1998-03-01
The measurement and control of cleanliness for critical surfaces during manufacturing and in service operations provides unique challenges in aerospace. For re-usable propulsion systems, such as the solid rocket motors, the current thrust for environmentally benign processes has had a major impact on programs designed for maintaining quality in the production of bondline surfaces. The major goal is to improve upon our ability to detect and identify possible contaminants which are detrimental to the integrity of the bondline. This effort requires an in-depth study of the possible sources of contamination, methodologies to detect and identify contaminants, discriminate between contaminants and chemical species caused by environmental conditions, and the effect of particular contaminants on the bondline integrity of the critical surfaces. This presentation will provide an overview of several optical methods used to detect and identify contamination on critical surfaces, currently being performed by the Surface Contamination and Analysis Team at Marshall Space Flight Center. The methods under development for contamination monitoring include FTIR and Near-IR SPectrometry, UV Fluorescence, and Variable Angle Spectroscopic Ellipsometry. Comparisons between these methods and the current primary tool, optical stimulation of electron emission for on-line inspection will be presented. Experiments include quantitative measurement of silicone and Conoco HD2 greases, metal hydroxides, tape residues, etc. on solid rocket motor surfaces.
Machining distortion prediction of aerospace monolithic components
Yun-bo BI; Qun-lin CHENG; Hui-yue DONG; Ying-lin KE
2009-01-01
To predict the distortion of aerospace monolithic components.a model is established to simulate the numerical control (NC)milling process using 3D finite element method(FEM).In this model,the cutting layer is simplified firstly.Then,the models of cutting force and cutting temperature are established to gain the cutting loads,which are applied to the mesh model of the part.Finally,a prototype of machining simulation environment is developed to simulate the milling process of a spar.Key factors influencing the distortion,such as initial residual stress,cutting loads,fixture layout,cutting sequence,and tool path are considered all together.The total distortion of the spar is predicted and an experiment is conducted to validate the numerical results.It is found that the maximum discrepancy between the simulation results and experiment values is 19.0%
SPH Modeling of Droplet Impact on Solid Boundary
李大鸣; 白玲; 李玲玲; 赵明宇
2014-01-01
A droplet undergoes spreading, rebounding or splashing when it impacts solid boundary, which is a typical phenomenon of free surface flow that exists widely in modern industry. Smoothed particle hydrodynamics (SPH) method is applied to numerically study the dynamical behaviors of the droplet impacting solid boundary, and both the spreading and rebounding phenomena of the droplet are reproduced in the simulation. The droplet deformation, flow fields and pressure fields inside the droplet at different moments are analyzed. Two important factors, the initial veloc-ity and diameter, are discussed in determining the maximum spreading factor, revealing that the maximum spreading factor increases with the increase of the impact velocity and droplet diameter respectively.
Lattice Structures For Aerospace Applications
Del Olmo, E.; Grande, E.; Samartin, C. R.; Bezdenejnykh, M.; Torres, J.; Blanco, N.; Frovel, M.; Canas, J.
2012-07-01
The way of mass reduction improving performances in the aerospace structures is a constant and relevant challenge in the space business. The designs, materials and manufacturing processes are permanently in evolution to explore and get mass optimization solutions at low cost. In the framework of ICARO project, EADS CASA ESPACIO (ECE) has designed, manufactured and tested a technology demonstrator which shows that lattice type of grid structures is a promising weight saving solution for replacing some traditional metallic and composite structures for space applications. A virtual testing methodology was used in order to support the design of a high modulus CFRP cylindrical lattice technology demonstrator. The manufacturing process, based on composite Automatic Fiber Placement (AFP) technology developed by ECE, allows obtaining high quality low weight lattice structures potentially applicable to a wide range of aerospace structures. Launcher payload adaptors, satellite platforms, antenna towers or instrument supports are some promising candidates.
Damage growth in aerospace composites
2015-01-01
This book presents novel methods for the simulation of damage evolution in aerospace composites that will assist in predicting damage onset and growth and thus foster less conservative designs which realize the promised economic benefits of composite materials. The presented integrated numerical/experimental methodologies are capable of taking into account the presence of damage and its evolution in composite structures from the early phases of the design (conceptual design) through to the detailed finite element method analysis and verification phase. The book is based on the GARTEUR Research Project AG-32, which ran from 2007 to 2012, and documents the main results of that project. In addition, the state of the art in European projects on damage evolution in composites is reviewed. While the high specific strength and stiffness of composite materials make them suitable for aerospace structures, their sensitivity to damage means that designing with composites is a challenging task. The new approaches describ...
Predictive model to describe water migration in cellular solid foods during storage
Voogt, J.A.; Hirte, A.; Meinders, M.B.J.
2011-01-01
BACKGROUND: Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge. RESULTS: Water migration in cellular solid foods
Predictive model to describe water migration in cellular solid foods during storage
Voogt, J.A.; Hirte, A.; Meinders, M.B.J.
2011-01-01
Background: Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge. Results: Water migration in cellular solid foods invo
Solid-Liquid equilibrium of n-alkanes using the Chain Delta Lattice Parameter model
Coutinho, João A.P.; Andersen, Simon Ivar; Stenby, Erling Halfdan
1996-01-01
-liquid equilibrium of n-alkanes ranging from n-C_20 to n-C_40.The model is further modified to achieve a more correct temperature dependence because it severely underestimates the excess enthalpy. It is shown that the ratio of excess enthalpy and entropy for n-alkane solid solutions, as happens for other solid...
A. N. Chichko
2006-01-01
Full Text Available The method of calculation and results of computer dynamics modeling of solid ingot skin in a crystallizer are presented in the paper. The paper shows influence of ingot drawing rate on dynamics of solid ingot skin growth in the continuous casting machine at steel grades used at Republic Unitary Enterprise «Belarussian Metallurgical Works» (BMZ.
Predictive model to describe water migration in cellular solid foods during storage
Voogt, J.A.; Hirte, A.; Meinders, M.B.J.
2011-01-01
BACKGROUND: Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge. RESULTS: Water migration in cellular solid foods invo
Prediction of the amount of urban waste solids by applying a gray theoretical model
无
2003-01-01
Urban waste solids are now becoming one of the most crucial environmental problems. There are several different kinds of technologies normally used for waste solids disposal, among which landfill is more favorable in China than others, especially for urban waste solids. Most of the design works up to now are based on a roughly estimation of the amount of urban waste solids without any theoretical support, which lead to a series problems. To meet the basic information requirements for the design work, the amount of the urban waste solids was predicted in this research by applying the gray theoretical model GM (1,1) through non-linear differential equation simulation. The model parameters were estimated with the least square method (LSM) by running a certain MATALAB program, and the hypothesis test results show that the residual between the prediction value and the actual value approximately comply with the normal distribution , and the probability of the residual within the range (-0.17, 0.19) is more than 95%, which indicate obviously that the model can be well used for the prediction of the amount of waste solids and those had been already testified by the latest two years data about the urban waste solids from Loudi City of China. With this model, the predicted amount of the waste solids produced in Loudi City in the next 30 years is 8049000 ton in total.
Integrated Models for Solid Waste Management in Tourism Regions: Langkawi Island, Malaysia
Elmira Shamshiry
2011-01-01
Full Text Available The population growth, changing consumption patterns, and rapid urbanization contribute significantly to the growing volumes of solid waste that are generated in urban settings. As the rate of urbanization increases, demand on the services of solid waste management increases. The rapid urban growth in Langkawi Island, Malaysia, combined with the increasing rates of solid waste production has provided evidence that the traditional solid waste management practices, particularly the methods of waste collection and disposal, are inefficient and quite nonsustainable. Accordingly, municipal managers and planners in Langkawi need to look for and adopt a model for solid waste management that emphasizes an efficient and sustainable management of solid wastes in Langkawi Island. This study presents the current practices of solid waste management in Langkawi Island, describes the composition of the solid waste generated in that area, and presents views of local residents and tourist on issues related to solid waste management like the aesthetic value of the island environment. The most important issue of this paper is that it is the first time that integrated solid waste management is investigated in the Langkawi Island.
Integrated Models for Solid Waste Management in Tourism Regions: Langkawi Island, Malaysia
Shamshiry, Elmira; Nadi, Behzad; Bin Mokhtar, Mazlin; Komoo, Ibrahim; Saadiah Hashim, Halimaton; Yahaya, Nadzri
2011-01-01
The population growth, changing consumption patterns, and rapid urbanization contribute significantly to the growing volumes of solid waste that are generated in urban settings. As the rate of urbanization increases, demand on the services of solid waste management increases. The rapid urban growth in Langkawi Island, Malaysia, combined with the increasing rates of solid waste production has provided evidence that the traditional solid waste management practices, particularly the methods of waste collection and disposal, are inefficient and quite nonsustainable. Accordingly, municipal managers and planners in Langkawi need to look for and adopt a model for solid waste management that emphasizes an efficient and sustainable management of solid wastes in Langkawi Island. This study presents the current practices of solid waste management in Langkawi Island, describes the composition of the solid waste generated in that area, and presents views of local residents and tourist on issues related to solid waste management like the aesthetic value of the island environment. The most important issue of this paper is that it is the first time that integrated solid waste management is investigated in the Langkawi Island. PMID:21904559
Integrated models for solid waste management in tourism regions: Langkawi Island, Malaysia.
Shamshiry, Elmira; Nadi, Behzad; Mokhtar, Mazlin Bin; Komoo, Ibrahim; Hashim, Halimaton Saadiah; Yahaya, Nadzri
2011-01-01
The population growth, changing consumption patterns, and rapid urbanization contribute significantly to the growing volumes of solid waste that are generated in urban settings. As the rate of urbanization increases, demand on the services of solid waste management increases. The rapid urban growth in Langkawi Island, Malaysia, combined with the increasing rates of solid waste production has provided evidence that the traditional solid waste management practices, particularly the methods of waste collection and disposal, are inefficient and quite nonsustainable. Accordingly, municipal managers and planners in Langkawi need to look for and adopt a model for solid waste management that emphasizes an efficient and sustainable management of solid wastes in Langkawi Island. This study presents the current practices of solid waste management in Langkawi Island, describes the composition of the solid waste generated in that area, and presents views of local residents and tourist on issues related to solid waste management like the aesthetic value of the island environment. The most important issue of this paper is that it is the first time that integrated solid waste management is investigated in the Langkawi Island.
Sandwiched composites in aerospace engineering
Nunes, J. P.; Silva,J.F.
2016-01-01
This chapter considers sandwiched composites used in aerospace applications. Typical sandwich composites consist of two thin, stiff, high-strength facing skins separated by a thick and light core. New developments in the type of face and core materials, production methods and joining and repair techniques are discussed in this chapter. It also discusses various properties as well as their main design methods for existing and future applications of sandwiched composites.
Magnetic Gearboxes for Aerospace Applications
Perez-Diaz, Jose Luis; Diez-Jimenez, Efren; Alvarez-Valenzuela, Marco A.; Sanchez-Garcia-Casarrubios, Juan; Cristache, Christian; Valiente-Blanco, Ignacio
2014-01-01
Magnetic gearboxes are contactless mechanisms for torque-speed conversion. They present no wear, no friction and no fatigue. They need no lubricant and can be customized for other mechanical properties as stiffness or damping. Additionally, they can protect structures and mechanisms against overloads, limitting the transmitted torque. In this work, spur, planetary and "magdrive" or "harmonic drive" configurations are compared considering their use in aerospace applications. The most recent test data are summarized to provide some useful help for the design engineer.
Carbon nanotechnology for future aerospace
Inam, Fawad
2014-01-01
Carbon nanotubes (CNTs) and graphene are being widely investigated for their addition in polymer, ceramic and metal matrices to prepare nanocomposites owing to the combination of the superlative mechanical, thermal, and electronic properties attributed to them. These materials are subject of significant research interest for their utilisation in an increasing number of applications including energy, transportation, defence, automotive, aerospace, sporting goods, and infrastructure sectors. Pa...
Communication for performance in aerospace
Aurelian Virgil BALUTA; Gabriela IOSIF
2016-01-01
The paper outlines rules for employees in the aerospace field about general procedures, accounting, budgets, employees involvement in the companies goals as a team or as a group. The quality of all communications activities is presented in correlation with performance. For us, performance means economic and social references, stability and credibility of the business and, not least, a good communication within the existing groups or teams. We take in account long-term, medium and short perfor...
无
2002-01-01
Whether the particle will be trapped by the solid-liquid interface or not is dependent on its moving behavior ahead of theinterface, so a mathematical model has been developed to investigate the movement of the particle ahead of the solid-liquidinterface. Based on the theory for the boundary layer, the fluid velocity field near the solid-liquid interface was obtained, andthe trajectories of particles were calculated by the equations of motion for particles. In this model, the drag force, the addedmass force, the buoyance force, the gravitational force, the Saffman force and the Basset history force are considered. Theresults show that the behavior of the particle ahead of the solid-liquid interface is affected by the physical property of theparticle and fluid flow. And in the continuous casting process, if it moves in the stream directed upward or downward nearvertical solid-liquid interface or in the horizontal flow under the solid-liquid interface, the particle with the diameter from 5μmto 60 μm can reach the solid-liquid interface. But if it moves in horizontal flow above the solid-liquid interface, only theparticle with the diameter from 5μm to 10μm can reach the solid-liquid interface.
Solid-state fermentation : modelling fungal growth and activity
Smits, J.P.
1998-01-01
In solid-state fermentation (SSF) research, it is not possible to separate biomass quantitatively from the substrate. The evolution of biomass dry weight in time can therefore not be measured. Of the aiternatives to dry weight available, glucosamine content is most promising.
Gluc
Solid-state fermentation: modelling fungal growth and activity.
Smits, J.P.
1998-01-01
In solid-state fermentation (SSF) research, it is not possible to separate biomass quantitatively from the substrate. The evolution of biomass dry weight in time can therefore not be measured. Of the aiternatives to dry weight available, glucosamine content is most promising.Glucosamine is the monom
New constitutive model for the study of creeping solids
王世文; 杨兆建; 冯建玲
2002-01-01
In this paper, a incremental form of constitutive laws for creeping studies are proposed. The equations are based on the concept of creep hardening surface. Damage effects were introduced to the new constitutive relations to study solids creeping effects with pre-existing damages. The present formula is easy to be adopted into other numerical procedures such as finite element methods.
KIBO Industry, innovates in aerospace
Paillard, Jean-Philippe
2016-07-01
The conquest of space is a true inspiration. Imagine a long-duration mission to a distant destination. What shall we take to produce our food? A cow, fish, chicken, or just eggs. In the current state of the animal production technologies are complicated and expensive to implement, except perhaps one: the breeding of edible insects. Based on this postulate KIBO in partnership with Space Agriculture Task Force and the university's department of Nutrition Nagoya most innovative research program is created in modern nutrition. This program is called Pegasus. Pegasus research program aims to develop food productions and modules applicable to the aerospace conquest. Kibo industry is the first entomocole production company creat in Europe to human food; it aims to become the world leader by 2020. Kibo industry is particularly specialized in producing entomosource (products with insects). The first phase of the program is to achieve an outcome cereal bar edible insect to aerospace. So we will present the issues and objectives of the project, for aerospace and us. Jean-Philippe Paillard is the KIBO industry CEO and Vice President of the FFPIDI insects farms federation. He is also the co computer alone authorization dossier on the market in Europe and therefore the privileged interlocutor of the General Directorate for Health and Customer Review on this topic. He intervened at the last conference on the insect organized by FAO in Wageningen and various universities in France.
Research and Development of Rapid Design Systems for Aerospace Structure
Schaeffer, Harry G.
1999-01-01
This report describes the results of research activities associated with the development of rapid design systems for aerospace structures in support of the Intelligent Synthesis Environment (ISE). The specific subsystems investigated were the interface between model assembly and analysis; and, the high performance NASA GPS equation solver software system in the Windows NT environment on low cost high-performance PCs.
Vacuum Ultraviolet Laser Probe of Chemical Dynamics of Aerospace Relevance
2012-09-12
valuable for modeling aerospace environments using the Direct Simulation Monte Carlo and Particles in Cell methods. Environments of interest to the...School of Chemical Biology and Biotechnology”, Shenzhen , China, Nov. 21, 2010. 29. C. Y. Ng, “The Role of Basic (Chemical) Research in Modern
Evaluation and Model of Performance of A Tubular Solid Oxide Fuel Cell
JIA Jun-xi; SHEN Sheng-qiang
2005-01-01
A simulation model was developed to analyze the steady state and transient operation of a tubular solid oxide fuel cell. The model covers both the electrochemical and the heat transfer models. The electrochemical model deals with the Nernst potential, ohmic polarization, activation polarization, and concentration polarization, while the heat transfer model concerns the heat transfer by conduction, convection and radiation. The numerical results show that the ohmic loss is the dominant one among the three polarizations in a cathode-supported solid oxide fuel cell and in the middle part of a solid oxide fuel cell the temperature is higher than those at both the ends. When the inlet temperature and the flow rates of the fuel and the oxidant are kept constantly, the temperature of the solid structure of the cell will increase due to the increase of power output of the cell from the initial state to the new one.
Solid modeling research at Lawrence Livermore National Laboratory: 1982-1985
Kalibjian, J.R.
1985-09-01
The Lawrence Livermore National Laboratory has sponsored solid modeling research for the past four years to assess this new technology and to determine its potential benefits to the Nuclear Weapons Complex. We summarize here the results of five projects implemented during our effort. First, we have installed two solid modeler codes, TIPS-1 (Technical Information Processing System-1) and PADL-2 (Part and Assembly Description Language), on the Laboratory's CRAY-1 computers. Further, we have extended the geometric coverage and have enhanced the graphics capabilities of the TIPS-1 modeler. To enhance solid modeler performance on our OCTOPUS computer system, we have also developed a method to permit future use of the Laboratory's network video system to provide high-resolution, shaded images at users' locations. Finally, we have begun to implement code that will link solid-modeler data bases to finite-element meshing codes.
Computational Control of Flexible Aerospace Systems
Sharpe, Lonnie, Jr.; Shen, Ji Yao
1994-01-01
The main objective of this project is to establish a distributed parameter modeling technique for structural analysis, parameter estimation, vibration suppression and control synthesis of large flexible aerospace structures. This report concentrates on the research outputs produced in the last two years of the project. The main accomplishments can be summarized as follows. A new version of the PDEMOD Code had been completed. A theoretical investigation of the NASA MSFC two-dimensional ground-based manipulator facility by using distributed parameter modelling technique has been conducted. A new mathematical treatment for dynamic analysis and control of large flexible manipulator systems has been conceived, which may provide a embryonic form of a more sophisticated mathematical model for future modified versions of the PDEMOD Codes.
Analytical prediction of aerospace vehicle vibration environments
Wilby, J. F.; Piersol, A. G.
1981-01-01
Considerable attention has been given recently to the formulation and validation of analytical models for the prediction of aerospace vehicle vibration response to acoustic and fluctuating pressures. This paper summarizes the development of such analytical models for two applications, (1) structural vibrations of the Space Shuttle orbiter vehicle due to broadband rocket noise and aerodynamic boundary layer turbulence, and (2) structural vibrations of general aviation aircraft due to discrete frequency propeller and reciprocating engine exhaust noise. In both cases, the spatial exterior excitations are convected pressure fields which are described on the basis of measured cross spectra (coherence and phase) information. Structural modal data are obtained from analytical predictions, and structural responses to appropriate excitation fields are calculated. The results are compared with test data, and the strengths and weaknesses of the analytical models are assessed.
Gladkov, Svyatoslav; Kochmann, Julian; Reese, Stefanie; Hütter, Markus; Svendsen, Bob
2016-04-01
The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on "standard" non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible-irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258-267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085-1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or "phase-field" models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435-479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44-62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a "thermodynamically consistent" phase-field model. Phys. D 69 (1993), 107-113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.
Tung, Nguyen-Thach; Park, Chun-Woong; Oh, Tack-oon; Kim, Ju-Young; Ha, Jung-Myung; Rhee, Yun-Seok; Park, Eun-Seok
2011-12-01
Rebamipide, a novel anti-ulcer agent, is listed in biopharmaceutics classification class IV because of its low aqueous solubility and permeability. Consequently, the bioavailability of rebamipide is under 10% in humans. The aim of this study was to increase the solubility and determine the effect of solubility enhancement on the bioavailability and efficacy of rebamipide (RBM). After taking into account the physiochemical properties of RBM (solubility, melting point, dosage etc.), solid dispersion was chosen as the solubility enhancement method. A rebamipide solid dispersion system containing the drug, l-lysine, PVP-VA 64 and poloxamer 407 was obtained from a spray-drying method. Solubility enhancement of RBM from the solid dispersion was determined by a dissolution test in 900 ml at pH 1.2. The bioavailability and efficacy of RBM solid dispersion were evaluated in a rat model. The aqueous solubility of RBM was improved 62.17 times by solid dispersion. The oral bioavailability of the drug was also increased 1.74-fold from solid dispersion compared with the reference product in a rat model. With regard to the anti-ulcer effect, the percentage inhibition of the solid dispersion was 2.71 times higher than that of the reference product in the ulcer-induced rat model. A solid dispersion of rebamipide was successfully formulated using the spray-drying method. Bioavailability and efficacy of rebamipide were increased significantly by solubility enhancement of the drug. © 2011 The Authors. JPP © 2011 Royal Pharmaceutical Society.
A visual LISP program for voxelizing AutoCAD solid models
Marschallinger, Robert; Jandrisevits, Carmen; Zobl, Fritz
2015-01-01
AutoCAD solid models are increasingly recognized in geological and geotechnical 3D modeling. In order to bridge the currently existing gap between AutoCAD solid models and the grid modeling realm, a Visual LISP program is presented that converts AutoCAD solid models into voxel arrays. Acad2Vox voxelizer works on a 3D-model that is made up of arbitrary non-overlapping 3D-solids. After definition of the target voxel array geometry, 3D-solids are scanned at grid positions and properties are streamed to an ASCII output file. Acad2Vox has a novel voxelization strategy that combines a hierarchical reduction of sampling dimensionality with an innovative use of AutoCAD-specific methods for a fast and memory-saving operation. Acad2Vox provides georeferenced, voxelized analogs of 3D design data that can act as regions-of-interest in later geostatistical modeling and simulation. The Supplement includes sample geological solid models with instructions for practical work with Acad2Vox.
Solids Modelling and Capture Simulation of Piperazine in Potassium Solvents
Fosbøl, Philip Loldrup; Maribo-Mogensen, Bjørn; Thomsen, Kaj
2012-01-01
Piperazine is an amine which is used both as an activator or promoter, but also as active component in CO2 capture solvents. High concentrations are being formulated to draw benefit of the PZ properties. This results in a risk of precipitation of PZ and other solid phases during capture. It could...... be a benefit to the capture process, but it could also result in unforeseen situations of potential hazardous operation, clogging, equipment failure etc.Security of the PZ process needs to be in focus. Flow assurance requires additional attention, especially due to the precipitation phenomenon. This entails...... equilibrium (VLE) calculation, heat capacity determination, and similar thermodynamic properties. It especially allows for determination of solid liquid equilibria (SLE) and heat of absorption/heat of desorption which are core variables in the determination of energy requirements for CO2 capture. In this work...
Modeling of vapor-liquid-solid equilibrium in gas - aqueous electrolyte systems
Thomsen, Kaj; Rasmussen, Peter
1999-01-01
A thermodynamic model for the description of vapor-liquid-solid equilibria is introduced. This model is a combination of the extended UNIQUAC model for electrolytes and the Soave-Redlich-Kwong cubic equation of state. The model has been applied to aqueous systems containing ammonia and/or carbon...
Two types of glitches in a solid quark star model
Lu, Jiguang; Zhou, Enping
2015-01-01
TThe glitch of anomalous X-ray pulsars \\& soft gamma repeaters (AXP/SGRs) usually accompanied with detectable energy releases manifesting as X-ray bursts or outbursts, while the glitch of some pulsars like Vela release negligible energy. We find that these two types of glitches can naturally correspond to two types of starquake of solid strange stars. By applying the EoS of quark cluster star and some realistic pulsar parameters, we can reproduce consistent results compared with previous cons...
Experimental and modeling study of a two-stage pilot scale high solid anaerobic digester system.
Yu, Liang; Zhao, Quanbao; Ma, Jingwei; Frear, Craig; Chen, Shulin
2012-11-01
This study established a comprehensive model to configure a new two-stage high solid anaerobic digester (HSAD) system designed for highly degradable organic fraction of municipal solid wastes (OFMSW). The HSAD reactor as the first stage was naturally separated into two zones due to biogas floatation and low specific gravity of solid waste. The solid waste was retained in the upper zone while only the liquid leachate resided in the lower zone of the HSAD reactor. Continuous stirred-tank reactor (CSTR) and advective-diffusive reactor (ADR) models were constructed in series to describe the whole system. Anaerobic digestion model No. 1 (ADM1) was used as reaction kinetics and incorporated into each reactor module. Compared with the experimental data, the simulation results indicated that the model was able to well predict the pH, volatile fatty acid (VFA) and biogas production.
A Lattice Boltzmann Model for Fluid-Solid Coupling Heat Transfer in Fractal Porous Media
CAI Jun; HUAI Xiu-Lan
2009-01-01
We report a lattice Boltzmann model that can be used to simulate fluid-solid coupling heat transfer in fractal porous media.A numerical simulation is conducted to investigate the temperature evolution under different ratios of thermal conductivity of solid matrix of porous media to that of fluid.The accordance of our simulation results with the solutions from the conventional CFD method indicates the feasibility and the reliability for the developed lattice Boltzmann model to reveal the phenomena and rules of fluid-solid coupling heat transfer in complex porous structures.
Mathematical Modelling of In-Chamber Processes in Hydrocombined Propellant Solid Rocket Motors
Nikolai A. Obukhov
1998-10-01
Full Text Available The special conditions of employment of commercial rockets in the sea environment has opened up new possibilities of improving motor performance. The interesting method suggests supplying water into the running motor. This paper reports the calculations and experiments carried out with solid propellant model setups. The results prove the validity of the proposed method and allow the refinement of calculation techniques for the prediction of solid rocket motor performance characteristics. The serviceability of the solid propellant charges working in combination with water is demonstrated. A mathematical model is proposed for the operation of a hydrocombined propellant motor with water and powdered additives applied to the combustion chamber."
The Need for an Aerospace Pharmacy Residency
Bayuse, T.; Schuyler, C.; Bayuse, Tina M.
2007-01-01
This viewgraph poster presentation reviews the rationale for a call for a new program in residency for aerospace pharmacy. Aerospace medicine provides a unique twist on traditional medicine, and a specialty has evolved to meet the training for physicians, and it is becoming important to develop such a program for training in pharmacy designed for aerospace. The reasons for this specialist training are outlined and the challenges of developing a program are reviewed.
Advanced Ceramic Materials for Future Aerospace Applications
Misra, Ajay
2015-01-01
With growing trend toward higher temperature capabilities, lightweight, and multifunctionality, significant advances in ceramic matrix composites (CMCs) will be required for future aerospace applications. The presentation will provide an overview of material requirements for future aerospace missions, and the role of ceramics and CMCs in meeting those requirements. Aerospace applications will include gas turbine engines, aircraft structure, hypersonic and access to space vehicles, space power and propulsion, and space communication.
Index of International Publications in Aerospace Medicine
2010-10-01
Aerospace Medicine technical reports are available in full-text from the Civil Aerospace Medical Institute’s publications Web site: www.faa.gov/library...Other Topics Related to Aerospace Medicine IBERIA Dirección Servicios al Cliente. Pasajeros con Movilidad Reducida. Consejos para el Viaje. Madrid...Enfermos. Madrid, Spain: Ministerio del Aire, Servicio Información Aeronáutica, 1956. National Air Transportation Association. NATA Bloodborne Pathogens
Harrand, V.; Choudry, A.
1987-01-01
The structure of a flexible arm derived from concatenation of the Stewart-Table-based links were studied. Solid modeling provides not only a realistic simulation, but is also essential for studying vision algorithms. These algorithms could be used for the adaptive control of the arm, using the well-known algorithms such as shape from shading, edge detection, orientation, etc. Details of solid modeling and its relation to vision based adaptive control are discussed.
Bilgili, M Sinan; Demir, Ahmet; Varank, Gamze
2009-01-01
The main goal of this study was to present a comparison of landfill performance with respect to solids decomposition. Biochemical methane potential (BMP) test was used to determine the initial and the remaining CH(4) potentials of solid wastes during 27 months of landfilling operation in two pilot...... and R2 reactors were 0.01571 and 0.01195 1/d, respectively. The correlation between the model and the experimental parameters was more than 95%, showing the good fit of the model....
Thermodynamic model of hardness: Particular case of boron-rich solids
Mukhanov, V. A.; Kurakevych, O. O.; Solozhenko, V. L.
2011-01-01
A number of successful theoretical models of hardness have been developed recently. A thermodynamic model of hardness, which supposes the intrinsic character of correlation between hardness and thermodynamic properties of solids, allows one to predict hardness of known or even hypothetical solids from the data on Gibbs energy of atomization of the elements, which implicitly determine the energy density per chemical bonding. The only structural data needed is the coordination number of the ato...
Virial modeling of gas-solid Joule-Thomson effect for argon-carbon aerosol
Rybolt, T.R. (Tennessee Univ., Chattanooga, TN (USA))
1989-12-01
This paper presents the history of and later experimentation with the Joule--Thomson effect. The effect is discussed in terms of its association with a gas-solid dispersion. Experimental measurements of aerosol cooling were compared to a viral model utilizing chromatographic second gas-solid viral coefficients. The author extends the application of this model to include the effects of higher order viral coefficients.
Developing Digital Aerospace to Build The Advanced Aerospace Corporation in The World
HouJunjie; LiuHaibin; GaoShiwen
2005-01-01
It is the strategic goal to develop digital aerospace for ChinaAerospace Science and Technology Corporation (CASC) to realize its leap development. In the paper, we expound the connotation of developing digital aerospace, i.e. the digitization of aerospace products, the informatization of R&D and manufacturing, the industrialization of software products, and the integration of information of ground and space sectors.
Microelectronics packaging research directions for aerospace applications
Galbraith, L.
2003-01-01
The Roadmap begins with an assessment of needs from the microelectronics for aerospace applications viewpoint. Needs Assessment is divided into materials, packaging components, and radiation characterization of packaging.
Aspects of modelling classical or synchronous modelling with Solid Edge ST 9
Goanta Adrian Mihai
2017-01-01
Full Text Available The current situation of the design activity is dependent on both the level of training of the human resources and the financial resources of companies required purchasing the design software packages and complex calculation equipment. Consequently, the situation is very diverse in the sense that there are design cases using only drawing software but also classical 3D or synchronous modelling situations, simple or integrated into software packages that meet the Product Lifecycle Management (PLM principles. The natural tendency in modelling and design is primarily to the high computing power integrated software or somewhat simplified versions that, however, allow at least FEA modelling, simulation and the related 2D documentation. The paper presents some aspects of modernity in synchronous modelling as compared to the classic one, made with 2016 version of Solid Edge software from SIEMENS. Basically there were studied and analysed aspects of modelling ease, speed of changes and also optimization of commands in the modelling process of the same piece in the two versions mentioned: classic and synchronous. It is also presented the alternative path from one method to another within the same process of piece modelling, depending on the advantages provided by each method. In other words, the work is based on a case study of modelling a piece under the two modelling versions of which some aspects were highlighted and conclusions were drawn.
Sorption of toxic organic compounds on wastewater solids: Mechanism and modeling
Wang, L.; Govind, R.; Dobbs, R.A.
1992-01-01
Sorption of toxic organic compounds on wastewater solids is an important process in conventional biological wastewater treatment systems. The extent of accumulation of toxic organic compounds by sorption onto wastewater solids not only affects the efficiency of the treatment system, but also impacts the management of wastewater solids. The study is an attempt to propose a mechanism for understanding the sorption phenomenon and to develop a model for sorption on wastewater solids based on the proposed mechanism. It was postulated that sorption was a combination of two processes: adsorption and partitioning. A sorption model was developed for both single component and multicomponent systems. The model was tested using single component experimental isotherm data of eight toxic organic compounds.
Allis, Damian G.; Hakey, Patrick M.; Korter, Timothy M.
2008-10-01
The terahertz (THz, far-infrared) spectrum of 3,4-methylene-dioxymethamphetamine hydrochloride (Ecstasy) is simulated using solid-state density functional theory. While a previously reported isolated-molecule calculation is noteworthy for the precision of its solid-state THz reproduction, the solid-state calculation predicts that the isolated-molecule modes account for only half of the spectral features in the THz region, with the remaining structure arising from lattice vibrations that cannot be predicted without solid-state molecular modeling. The molecular origins of the internal mode contributions to the solid-state THz spectrum, as well as the proper consideration of the protonation state of the molecule, are also considered.
Internal Flow Simulation of High-Performance Solid Rockets using a k-ωTurbulence Model
V.R. SANAL KUMAR; H.D. KIM; B.N. RAGHUNANDAN; T. SETOGUCHI; S. RAGHUNATHAN
2005-01-01
@@ For technological reasons many high-performance solid rocket motors are made from segmented propellant grains with non-uniform port geometry. In this paper parametric studies have been carried out to examine the geometric dependence of transient flow features in solid rockets with non-uniform ports. Numerical computations have been carried out in an inert simulator of solid propellant rocket motor with the aid of a standard k-ω turbulence model. It was seen that the damping of the temperature fluctuation is faster in solid rocket with convergent port than with divergent port geometry. We inferred that the damping of the flow fluctuations using the port geometry is a meaningful objective for the suppression and control of the instability and/or pressure/thrust oscillations during the starting transient of solid rockets.
Cybersecurity for aerospace autonomous systems
Straub, Jeremy
2015-05-01
High profile breaches have occurred across numerous information systems. One area where attacks are particularly problematic is autonomous control systems. This paper considers the aerospace information system, focusing on elements that interact with autonomous control systems (e.g., onboard UAVs). It discusses the trust placed in the autonomous systems and supporting systems (e.g., navigational aids) and how this trust can be validated. Approaches to remotely detect the UAV compromise, without relying on the onboard software (on a potentially compromised system) as part of the process are discussed. How different levels of autonomy (task-based, goal-based, mission-based) impact this remote characterization is considered.
Detailed Multi-dimensional Modeling of Direct Internal Reforming Solid Oxide Fuel Cells.
Tseronis, K; Fragkopoulos, I S; Bonis, I; Theodoropoulos, C
2016-06-01
Fuel flexibility is a significant advantage of solid oxide fuel cells (SOFCs) and can be attributed to their high operating temperature. Here we consider a direct internal reforming solid oxide fuel cell setup in which a separate fuel reformer is not required. We construct a multidimensional, detailed model of a planar solid oxide fuel cell, where mass transport in the fuel channel is modeled using the Stefan-Maxwell model, whereas the mass transport within the porous electrodes is simulated using the Dusty-Gas model. The resulting highly nonlinear model is built into COMSOL Multiphysics, a commercial computational fluid dynamics software, and is validated against experimental data from the literature. A number of parametric studies is performed to obtain insights on the direct internal reforming solid oxide fuel cell system behavior and efficiency, to aid the design procedure. It is shown that internal reforming results in temperature drop close to the inlet and that the direct internal reforming solid oxide fuel cell performance can be enhanced by increasing the operating temperature. It is also observed that decreases in the inlet temperature result in smoother temperature profiles and in the formation of reduced thermal gradients. Furthermore, the direct internal reforming solid oxide fuel cell performance was found to be affected by the thickness of the electrochemically-active anode catalyst layer, although not always substantially, due to the counter-balancing behavior of the activation and ohmic overpotentials.
Life-cycle assessment of municipal solid wastes: development of the WASTED model.
Diaz, R; Warith, M
2006-01-01
This paper describes the development of the Waste Analysis Software Tool for Environmental Decisions (WASTED) model. This model provides a comprehensive view of the environmental impacts of municipal solid waste management systems. The model consists of a number of separate submodels that describe a typical waste management process: waste collection, material recovery, composting, energy recovery from waste and landfilling. These submodels are combined to represent a complete waste management system. WASTED uses compensatory systems to account for the avoided environmental impacts derived from energy recovery and material recycling. The model is designed to provide solid waste decision-makers and environmental researchers with a tool to evaluate waste management plans and to improve the environmental performance of solid waste management strategies. The model is user-friendly and compares favourably with other earlier models.
Nonisothermal particle modeling of municipal solid waste combustion with heavy metal vaporization
Mazza, G. [Facultad de Ingenieria, Departamento de Quimica, Universidad Nacional del Comahue, IDEPA (CONICET - UNCo), Buenos Aires 1400, 8300 Neuquen (Argentina); Falcoz, Q.; Gauthier, D.; Flamant, G. [Laboratoire Procedes et Materiaux et Energie Solaire (CNRS-PROMES), 7 Rue du Four Solaire, Odeillo, 66120 Font-Romeu Cedex (France); Soria, J. [Facultad de Ingenieria, Departamento de Quimica, Universidad Nacional del Comahue, IDEPA (CONICET - UNCo), Buenos Aires 1400, 8300 Neuquen (Argentina); Laboratoire Procedes et Materiaux et Energie Solaire (CNRS-PROMES), 7 Rue du Four Solaire, Odeillo, 66120 Font-Romeu Cedex (France)
2010-12-15
A particulate model was developed for municipal solid-waste incineration in a fluidized bed combining solid-waste-particle combustion and heavy metal vaporization from the burning particles. Based on a simpler, isothermal version presented previously, this model combines an asymptotic-combustion model for carbonaceous-solid combustion and a shrinking-core model to describe the heavy metal vaporization phenomenon, in which the particle is now considered nonisothermal. A parametric study is presented that shows the influence of temperature on the global metal-vaporization process. The simulation results are compared to experimental data obtained with a lab-scale fluid bed incinerator and to the results of the simpler isothermal model. It is shown that conduction in the particle strongly affects the variation of the vaporization rate with time and that the present version of the model well fits both the shape of the plots and the maximum heavy metal vaporization rates for all bed temperatures. (author)
Marra, Dario; Polverino, Pierpaolo; Sorrentino, Marco
2016-01-01
This book presents methodologies for optimal design of control and diagnosis strategies for Solid Oxide Fuel Cell systems. A key feature of the methodologies presented is the exploitation of modelling tools that balance accuracy and computational burden.
Optimization of a new flow design for solid oxide cells using computational fluid dynamics modelling
Duhn, Jakob Dragsbæk; Jensen, Anker Degn; Wedel, Stig;
2016-01-01
Design of a gas distributor to distribute gas flow into parallel channels for Solid Oxide Cells (SOC) is optimized, with respect to flow distribution, using Computational Fluid Dynamics (CFD) modelling. The CFD model is based on a 3d geometric model and the optimized structural parameters include...
Fourth NASA Workshop on Computational Control of Flexible Aerospace Systems, part 2
Taylor, Lawrence W., Jr. (Compiler)
1991-01-01
A collection of papers presented at the Fourth NASA Workshop on Computational Control of Flexible Aerospace Systems is given. The papers address modeling, systems identification, and control of flexible aircraft, spacecraft and robotic systems.
Reedy, E. D. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Chambers, Robert S. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Hughes, Lindsey Gloe [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Kropka, Jamie Michael [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Stavig, Mark E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Stevens, Mark J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
2015-09-01
The performance and reliability of many mechanical and electrical components depend on the integrity of po lymer - to - solid interfaces . Such interfaces are found in adhesively bonded joints, encapsulated or underfilled electronic modules, protective coatings, and laminates. The work described herein was aimed at improving Sandia's finite element - based capability to predict interfacial crack growth by 1) using a high fidelity nonlinear viscoelastic material model for the adhesive in fracture simulations, and 2) developing and implementing a novel cohesive zone fracture model that generates a mode - mixity dependent toughness as a natural consequence of its formulation (i.e., generates the observed increase in interfacial toughness wi th increasing crack - tip interfacial shear). Furthermore, molecular dynamics simulations were used to study fundamental material/interfa cial physics so as to develop a fuller understanding of the connection between molecular structure and failure . Also reported are test results that quantify how joint strength and interfacial toughness vary with temperature.
Ultrasonic Characterization of Aerospace Composites
Leckey, Cara; Johnston, Patrick; Haldren, Harold; Perey, Daniel
2015-01-01
Composite materials have seen an increased use in aerospace in recent years and it is expected that this trend will continue due to the benefits of reduced weight, increased strength, and other factors. Ongoing work at NASA involves the investigation of the large-scale use of composites for spacecraft structures (SLS components, Orion Composite Crew Module, etc). NASA is also involved in work to enable the use of composites in advanced aircraft structures through the Advanced Composites Project (ACP). In both areas (space and aeronautics) there is a need for new nondestructive evaluation and materials characterization techniques that are appropriate for characterizing composite materials. This paper will present an overview of NASA's needs for characterizing aerospace composites, including a description of planned and ongoing work under ACP for the detection of composite defects such as fiber waviness, reduced bond strength, delamination damage, and microcracking. The research approaches include investigation of angle array, guided wave, and phase sensitive ultrasonic methods. The use of ultrasonic simulation tools for optimizing and developing methods will also be discussed.
Communication for performance in aerospace
Aurelian Virgil BALUTA
2016-12-01
Full Text Available The paper outlines rules for employees in the aerospace field about general procedures, accounting, budgets, employees involvement in the companies goals as a team or as a group. The quality of all communications activities is presented in correlation with performance. For us, performance means economic and social references, stability and credibility of the business and, not least, a good communication within the existing groups or teams. We take in account long-term, medium and short performance for a new and modern field such as the aerospace industry. The paper highlights the group communication aspects, the process needed to optimize communication within a group, the team characteristics and mission, the team involvement versus group involvement, organization of the work team and defining/definition of roles in a team according to individual skills and some technics; to apply the Belbin test for determining the role of individuals within the team, for identifying the types of communication in order to get the information transmitted to the different types of individuals such as “analytical type”, “director type”, “friendly type”, “expressive type”, the needs and interest of these individuals, assessing how the information was received and the impact of the feedback.
Hossein Asefi
2015-09-01
Full Text Available Municipal solid waste management is one of the challenging issues in mega cities due to various interrelated factors such as operational costs and environmental concerns. Cost as one of the most significant constraints of municipal solid waste management can be effectively economized by efficient planning approaches. Considering diverse waste types in an integrated municipal solid waste system, a mathematical model of the location-routing problem is formulated and solved in this study in order to minimize the total cost of transportation and facility establishment.
ZikangWu; ArneJakobsen; 等
1994-01-01
The pupose of this paper is to investigate the validity of a lumped model,i.e.a reaction front model,for the simulation of solid absorption process.A distributed model is developed for solid absorption process,and a dimensionless RF number is suggested to predict the qualitative shape of reaction degree profile.The simulation results from the reaction front model are compared with those from the distributed model solved by a finite difference scheme,and it is shown that they are in good agreement in almost all cased.no matter whether there is reaction front or not.
Compressive strength of delaminated aerospace composites.
Butler, Richard; Rhead, Andrew T; Liu, Wenli; Kontis, Nikolaos
2012-04-28
An efficient analytical model is described which predicts the value of compressive strain below which buckle-driven propagation of delaminations in aerospace composites will not occur. An extension of this efficient strip model which accounts for propagation transverse to the direction of applied compression is derived. In order to provide validation for the strip model a number of laminates were artificially delaminated producing a range of thin anisotropic sub-laminates made up of 0°, ±45° and 90° plies that displayed varied buckling and delamination propagation phenomena. These laminates were subsequently subject to experimental compression testing and nonlinear finite element analysis (FEA) using cohesive elements. Comparison of strip model results with those from experiments indicates that the model can conservatively predict the strain at which propagation occurs to within 10 per cent of experimental values provided (i) the thin-film assumption made in the modelling methodology holds and (ii) full elastic coupling effects do not play a significant role in the post-buckling of the sub-laminate. With such provision, the model was more accurate and produced fewer non-conservative results than FEA. The accuracy and efficiency of the model make it well suited to application in optimum ply-stacking algorithms to maximize laminate strength.
Solid-liquid phase equilibria of the Gaussian core model fluid.
Mausbach, Peter; Ahmed, Alauddin; Sadus, Richard J
2009-11-14
The solid-liquid phase equilibria of the Gaussian core model are determined using the GWTS [J. Ge, G.-W. Wu, B. D. Todd, and R. J. Sadus, J. Chem. Phys. 119, 11017 (2003)] algorithm, which combines equilibrium and nonequilibrium molecular dynamics simulations. This is the first reported use of the GWTS algorithm for a fluid system displaying a reentrant melting scenario. Using the GWTS algorithm, the phase envelope of the Gaussian core model can be calculated more precisely than previously possible. The results for the low-density and the high-density (reentrant melting) sides of the solid state are in good agreement with those obtained by Monte Carlo simulations in conjunction with calculations of the solid free energies. The common point on the Gaussian core envelope, where equal-density solid and liquid phases are in coexistence, could be determined with high precision.
iSTEM: The Aerospace Engineering Challenge
English, Lyn D.; King, Donna T.; Hudson, Peter; Dawes, Les
2014-01-01
The authors developed The Paper Plane Challenge as one of a three-part response to The Aerospace Engineering Challenge. The Aerospace Engineering Challenge was the second of three multi-part activities that they had developed with the teachers during the year. Their aim was to introduce students to the exciting world of engineering, where they…
The 42nd Aerospace Mechanism Symposium
Boesiger, Edward A. (Editor); Hakun, Claef (Editor)
2014-01-01
The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production, and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development, and flight certification of new mechanisms.
Henkel Technologies and Products for China Aerospace
Michael Cichon; Helen Wei Li; Alex Wong; Stan Lehmann; Raymond Wong
2006-01-01
Epoxy structural adhesives and composites have been in use for many years for the construction of aerospace vehicles. Henkel provides many epoxy products. Many other resin systems have been evaluated and several, such as imide,phenolic and cyanate ester, have also achieved significant use. Henkel's newly developed "Epsilon" chemistry demonstrates unique features that benefit application in aerospace structure that use adhesives and composites.
Application of the PM6 method to modeling the solid state
Stewart, James J. P.
2008-01-01
The applicability of the recently developed PM6 method for modeling various properties of a wide range of organic and inorganic crystalline solids has been investigated. Although the geometries of most systems examined were reproduced with good accuracy, severe errors were found in the predicted structures of a small number of solids. The origin of these errors was investigated, and a strategy for improving the method proposed. Figure Detail of Structure of Dihydrogen Phosphate in KH2PO4 (upp...
Modeling of polymer networks for application to solid propellant formulating
Marsh, H. E.
1979-01-01
Methods for predicting the network structural characteristics formed by the curing of pourable elastomers were presented; as well as the logic which was applied in the development of mathematical models. A universal approach for modeling was developed and verified by comparison with other methods in application to a complex system. Several applications of network models to practical problems are described.
Powered Flight The Engineering of Aerospace Propulsion
Greatrix, David R
2012-01-01
Whilst most contemporary books in the aerospace propulsion field are dedicated primarily to gas turbine engines, there is often little or no coverage of other propulsion systems and devices such as propeller and helicopter rotors or detailed attention to rocket engines. By taking a wider viewpoint, Powered Flight - The Engineering of Aerospace Propulsion aims to provide a broader context, allowing observations and comparisons to be made across systems that are overlooked by focusing on a single aspect alone. The physics and history of aerospace propulsion are built on step-by-step, coupled with the development of an appreciation for the mathematics involved in the science and engineering of propulsion. Combining the author’s experience as a researcher, an industry professional and a lecturer in graduate and undergraduate aerospace engineering, Powered Flight - The Engineering of Aerospace Propulsion covers its subject matter both theoretically and with an awareness of the practicalities of the industry. To ...
Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.
1996-01-01
The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. Little is also known about the intermediary-based system that is used to transfer the results of federally funded R&D to the U.S. aerospace industry. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DOD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports, present a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis the technical communication practices of U.S. aerospace engineers and scientists who were members of the American Institute of Aeronautics and Astronautics (AIAA) and identified themselves as educators.
Spectroscopic Measurement Techniques for Aerospace Flows
Danehy, Paul M.; Bathel, Brett F.; Johansen, Craig T.; Cutler, Andrew D.; Hurley, Samantha
2014-01-01
The conditions that characterize aerospace flows are so varied, that a single diagnostic technique is not sufficient for its measurement. Fluid dynamists use knowledge of similarity to help categorize and focus on different flow conditions. For example, the Reynolds number represents the ratio of inertial to viscous forces in a flow. When the velocity scales, length scales, and gas density are large and the magnitude of the molecular viscosity is low, the Reynolds number becomes large. This corresponds to large scale vehicles (e.g Airbus A380), fast moving objects (e.g. artillery projectiles), vehicles in dense fluids (e.g. submarine in water), or flows with low dynamic viscosity (e.g. skydiver in air). In each of these cases, the inertial forces dominate viscous forces, and unsteady turbulent fluctuations in the flow variables are observed. In contrast, flows with small length scales (e.g. dispersion of micro-particles in a solid rocket nozzle), slow moving objects (e.g. micro aerial vehicles), flows with low density gases (e.g. atmospheric re-entry), or fluids with a large magnitude of viscosity (e.g. engine coolant flow), all have low Reynolds numbers. In these cases, viscous forces become very important and often the flows can be steady and laminar. The Mach number, which is the ratio of the velocity to the speed of sound in the medium, also helps to differentiate types of flows. At very low Mach numbers, acoustic waves travel much faster than the object, and the flow can be assumed to be incompressible (e.g. Cessna 172 aircraft). As the object speed approaches the speed of sound, the gas density can become variable (e.g. flow over wing of Learjet 85). When the object speed is higher than the speed of sound (Ma > 1), the presences of shock waves and other gas dynamic features can become important to the vehicle performance (e.g. SR-71 Blackbird). In the hypersonic flow regime (Ma > 5), large changes in temperature begin to affect flow properties, causing real
Transient Burning Rate Model for Solid Rocket Motor Internal Ballistic Simulations
David R. Greatrix
2008-01-01
Full Text Available A general numerical model based on the Zeldovich-Novozhilov solid-phase energy conservation result for unsteady solid-propellant burning is presented in this paper. Unlike past models, the integrated temperature distribution in the solid phase is utilized directly for estimating instantaneous burning rate (rather than the thermal gradient at the burning surface. The burning model is general in the sense that the model may be incorporated for various propellant burning-rate mechanisms. Given the availability of pressure-related experimental data in the open literature, varying static pressure is the principal mechanism of interest in this study. The example predicted results presented in this paper are to a substantial extent consistent with the corresponding experimental firing response data.
Modelling solid-convective flash pyrolysis of straw and wood in the Pyrolysis Centrifuge Reactor
Bech, Niels; Larsen, Morten Boberg; Jensen, Peter Arendt
2009-01-01
Less than a handful of solid-convective pyrolysis reactors for the production of liquid fuel from biomass have been presented and for only a single reactor a detailed mathematical model has been presented. In this article we present a predictive mathematical model of the pyrolysis process...... in the Pyrolysis Centrifuge Reactor, a novel solid-convective flash pyrolysis reactor. The model relies on the original concept for ablative pyrolysis of particles being pyrolysed through the formation of an intermediate liquid compound which is further degraded to form liquid organics, char, and gas. To describe...... that the reacting particle continuously shed the formed char layer....
Traveling waves for models of phase transitions of solids driven by configurational forces
Kawashima, Shuichi
2009-01-01
This article is concerned with the existence of traveling wave solutions, including standing waves, to some models based on configurational forces, describing respectively the diffusionless phase transformations of solid materials, e.g., Steel, and phase transitions due to interface motion by interface diffusion, e.g., Sintering. These models are recently proposed by Alber and Zhu. We consider both the order-parameter-conserved case and the non-conserved one, under suitable assumptions. Also we compare our results with the corresponding ones for the Allen-Cahn and the Cahn-Hilliard equations coupled with linear elasticity, which are models for diffusion-dominated phase transformations in elastic solids.
Application of simple dynamic recurrent neural networks in solid granule flowrate modeling
Du, Yun; Sun, Huiqin; Tian, Qiang; Ren, Haiping; Zhang, Suying
2008-10-01
To build the solid granule flowrate model by the simple dynamic recurrent neural network (SRNN) is presented in this paper. Because of the dynamic recurrent neural network has the characteristic of intricate network structure and slow training algorithm rate, the simple recurrent neural network without the weight values on recursion layer is studied. The recurrent prediction error (RPE) learning algorithm for SRNN by adjustment the weight value and the threshold value is reduced. The modeling result of solid granule flowrate indicates that it has fast convergence rate and the high precision the model. It can be used on real time.
Modelling of Physical, Chemical, and Material Properties of Solid Oxide Fuel Cells
Jakub Kupecki
2015-01-01
Full Text Available This paper provides a review of modelling techniques applicable for system-level studies to account for physical, chemical, and material properties of solid oxide fuel cells. Functionality of 0D to 3D models is discussed and selected examples are given. Author provides information on typical length scales in evaluation of power systems with solid oxide fuel cells. In each section, proper examples of previous studies done in the field of 0D–3D modelling are recalled and discussed.
Solid-state three-step model for high-harmonic generation from periodic crystals
Ikemachi, Takuya; Sato, Takeshi; Yumoto, Junji; Kuwata-Gonokami, Makoto; Ishikawa, Kenichi L
2016-01-01
We study high-harmonic generation (HHG) from solids driven by intense laser pulses using the time-dependent Schrodinger equation for a one-dimensional model periodic crystal. Based on the simulation results, we propose a simple model that can quantitatively explain many aspects of solid- state HHG, some of which have been experimentally observed. Incorporating interband tunneling, intraband acceleration, and recombination with the valence-band hole, our model can be viewed as a solid-state counterpart of the familiar three-step model highly successful for gas-phase HHG and provides a unified basis to understand HHG from gaseous media and solid-state materials. The solid-state three-step model describes how, by repeating intraband acceleration and interband tunneling, electrons climb up across multiple conduction bands. The key parameter in predicting the HHG spectrum structure from the band-climbing process is the peak-to-valley (or valley-to-peak) full amplitude of the pulse vector potential $A(t)$. When the...
SPH-DCDEM model for arbitrary geometries in free surface solid-fluid flows
Canelas, Ricardo B.; Crespo, Alejandro J. C.; Domínguez, Jose M.; Ferreira, Rui M. L.; Gómez-Gesteira, Moncho
2016-05-01
A unified discretization of rigid solids and fluids is introduced, allowing for resolved simulations of fluid-solid phases within a meshless framework. The numerical solution, attained by Smoothed Particle Hydrodynamics (SPH) and a variation of Discrete Element Method (DEM), the Distributed Contact Discrete Element Method (DCDEM) discretization, is achieved by directly considering solid-solid and solid-fluid interactions. The novelty of the work is centred on the generalization of the coupling of the DEM and SPH methodologies for resolved simulations, allowing for state-of-the-art contact mechanics theories to be used in arbitrary geometries, while fluid to solid and vice versa momentum transfers are accurately described. The methods are introduced, analysed and discussed. Initial validations on the DCDEM and the fluid coupling are presented, drawing from test cases in the literature. An experimental campaign serves as a validation point for complex, large scale solid-fluid flows, where a set of blocks in several configurations is subjected to a dam-break wave. Blocks are tracked and positions are then compared between experimental data and the numerical solutions. A Particle Image Velocimetry (PIV) technique allows for the quantification of the flow field and direct comparison with numerical data. The results show that the model is accurate and is capable of treating highly complex interactions, such as transport of debris or hydrodynamic actions on structures, if relevant scales are reproduced.
Solid-state-drives (SSDs) modeling simulation tools & strategies
2017-01-01
This book introduces simulation tools and strategies for complex systems of solid-state-drives (SSDs) which consist of a flash multi-core microcontroller plus NAND flash memories. It provides a broad overview of the most popular simulation tools, with special focus on open source solutions. VSSIM, NANDFlashSim and DiskSim are benchmarked against performances of real SSDs under different traffic workloads. PROs and CONs of each simulator are analyzed, and it is clearly indicated which kind of answers each of them can give and at a what price. It is explained, that speed and precision do not go hand in hand, and it is important to understand when to simulate what, and with which tool. Being able to simulate SSD’s performances is mandatory to meet time-to-market, together with product cost and quality. Over the last few years the authors developed an advanced simulator named “SSDExplorer” which has been used to evaluate multiple phenomena with great accuracy, from QoS (Quality Of Service) to Read Retry, fr...
3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups
Scalfani, Vincent F.; Vaid, Thomas P.
2014-01-01
Tangible models help students and researchers visualize chemical structures in three dimensions (3D). 3D printing offers a unique and straightforward approach to fabricate plastic 3D models of molecules and extended solids. In this article, we prepared a series of digital 3D design files of molecular structures that will be useful for teaching…
A grain size distribution model for non-catalytic gas-solid reactions
Heesink, Albertus B.M.; Prins, W.; van Swaaij, Willibrordus Petrus Maria
1993-01-01
A new model to describe the non-catalytic conversion of a solid by a reactant gas is proposed. This so-called grain size distribution (GSD) model presumes the porous particle to be a collection of grains of various sizes. The size distribution of the grains is derived from mercury porosimetry measur
3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups
Scalfani, Vincent F.; Vaid, Thomas P.
2014-01-01
Tangible models help students and researchers visualize chemical structures in three dimensions (3D). 3D printing offers a unique and straightforward approach to fabricate plastic 3D models of molecules and extended solids. In this article, we prepared a series of digital 3D design files of molecular structures that will be useful for teaching…
Model for on-line moisture-content control during solid-state fermentation
Nagel, F.J.J.I.; Tramper, J.; Bakker, M.S.N.; Rinzema, A.
2001-01-01
In this study we describe a model that estimates the extracellular (nonfungal) and overall water contents of wheat grains during solid-state fermentation (SSF) with Aspergillus oryzae, using on-line measurements of oxygen, carbon dioxide, and water vapor in the gas phase. The model uses elemental ba
Exploring Solid-State Structure and Physical Properties: A Molecular and Crystal Model Exercise
Bindel, Thomas H.
2008-01-01
A crystal model laboratory exercise is presented that allows students to examine relations among the microscopic-macroscopic-symbolic levels, using crystalline mineral samples and corresponding crystal models. Students explore the relationship between solid-state structure and crystal form. Other structure-property relationships are explored. The…
Exploring Solid-State Structure and Physical Properties: A Molecular and Crystal Model Exercise
Bindel, Thomas H.
2008-01-01
A crystal model laboratory exercise is presented that allows students to examine relations among the microscopic-macroscopic-symbolic levels, using crystalline mineral samples and corresponding crystal models. Students explore the relationship between solid-state structure and crystal form. Other structure-property relationships are explored. The…
Viterna, Larry A.
1991-01-01
Detailed understanding of heat transfer and fluid flow is required for many aerospace thermal systems. These systems often include phase change and operate over a range of accelerations or effective gravitational fields. An approach to analyzing such systems is presented which requires the simultaneous solution of the conservation laws of energy, momentum, and mass, as well as an equation of state. The variable property form of the governing equations are developed in two-dimensional Cartesian coordinates for a Newtonian fluid. A numerical procedure for solving the governing equations is presented and implemented in a computer program. The Galerkin form of the finite element method is used to solve the spatial variation of the field variables, along with the implicit Crank-Nicolson time marching algorithm. Quadratic Langrangian elements are used for the internal energy and the two components of velocity. Linear Lagrangian elements are used for the pressure. The location of the solid/liquid interface as well as the temperatures are determined form the calculated internal energy and pressure. This approach is quite general in that it can describe heat transfer without phase change, phase change with a sharp interface, and phase change without an interface. Analytical results from this model are compared to those of other researchers studying transient conduction, convection, and phase change and are found to be in good agreement. The numerical procedure presented requires significant computer resources, but this is not unusual when compared to similar studies by other researchers. Several methods are suggested to reduce the computational times.
Digital Library for Aerospace Education
Kudashev, Å. B.
The article reviews the experience of the development of digital digital library for the problems in organisation of state-of-the-art education in remote sensing for environmental research. Information-education resources are installed on the Web-Server of Space Research Institute. Web Server was organized in the form the Remote Sensing Data Server, and Metadata Server on the base of digital catalogues with satellite imagery. The integration of Russian Satellite Data of Remote Sensing would conclude the Digital Library. For this project we had the following guiding principles: create the Web resources of Satellite Data, Metadata, and Geospatial Information for University community; provide the information support for the Inter-University Aerospace Centre; provide free Web access and obtaining satellite images over Internet; provide the information exchange and data acquisition.
Energy Storage for Aerospace Applications
Perez-Davis, Marla E.; Loyselle, Patricia L.; Hoberecht, Mark A.; Manzo, Michelle A.; Kohout, Lisa L.; Burke, Kenneth A.; Cabrera, Carlos R.
2001-01-01
The NASA Glenn Research Center (GRC) has long been a major contributor to the development and application of energy storage technologies for NASAs missions and programs. NASA GRC has supported technology efforts for the advancement of batteries and fuel cells. The Electrochemistry Branch at NASA GRC continues to play a critical role in the development and application of energy storage technologies, in collaboration with other NASA centers, government agencies, industry and academia. This paper describes the work in batteries and fuel cell technologies at the NASA Glenn Research Center. It covers a number of systems required to ensure that NASAs needs for a wide variety of systems are met. Some of the topics covered are lithium-based batteries, proton exchange membrane (PEM) fuel cells, and nanotechnology activities. With the advances of the past years, we begin the 21st century with new technical challenges and opportunities as we develop enabling technologies for batteries and fuel cells for aerospace applications.
Development of mathematical models for solid state switching devices
Raburn, W. D.; Kim, J. C.
1980-01-01
Models are developed for two types of remote power controllers (RPC). The models give the equations for the currents and voltages for all elements of passive loads as a function of time for both turn-on and turn-off. It is shown that the RPC can be considered as a combination of current and voltage sources. Equations are given for these sources which are essentially independent of the load being turned on and off. Experimental results are given for several types of loads and comparisons are made with the results obtained using the models.
Analytical model of the combustion of multicomponent solid propellants
Cohen, N. S.; Price, C. F.; Strand, L. D.
1977-01-01
Multiple flame models derived for simple composite propellants are extended to describe the combustion of propellants containing multimodal particle sizes, mixed oxidizers and monopropellant binders. Models combining the component contributions to propellant surface structure, flame structure and energy distribution are based in part upon experimental observations and in part upon hypotheses constrained to provide reasonable agreement with measured burning rate characteristics. The methods employed consist of superposition, interaction and iteration. The computerized model is applied to explain the effects of multiple ingredients and to discuss burning rate tailoring problems of current interest.
Ng-Thow-Hing, Victor; Agur, Anne; Ball, Kevin A.; Fiume, Eugene; McKee, Nancy
1998-05-01
We introduce a mathematical primitive called the B-spline solid that can be used to create deformable models of muscle shape. B-spline solids can be used to model skeletal muscle for the purpose of building a data library of reusable, deformable muscles that are reconstructed from actual muscle data. Algorithms are provided for minimizing shape distortions that may be caused when fitting discrete sampled data to a continuous B-spline solid model. Visible Human image data provides a good indication of the perimeter of a muscle, but is not suitable for providing internal muscle fiber bundle arrangements which are important for physical simulation of muscle function. To obtain these fiber bundle orientations, we obtain 3-D muscle fiber bundle coordinates by triangulating optical images taken from three different camera views of serially dissected human soleus specimens. B-spline solids are represented as mathematical three-dimensional vector functions which can parameterize an enclosed volume as well as its boundary surface. They are based on B-spline basis functions, allowing local deformations via adjustable control points and smooth continuity of shape. After the B-spline solid muscle model is fitted with its external surface and internal volume arrangements, we can subsequently deform its shape to allow simulation of animated muscle tissue.
Model of sustainable utilization of organic solids waste in Cundinamarca, Colombia
Solanyi Castañeda Torres
2017-05-01
Full Text Available Introduction: This article considers a proposal of a model of use of organic solids waste for the department of Cundinamarca, which responds to the need for a tool to support decision-making for the planning and management of organic solids waste. Objective: To perform an approximation of a conceptual technical and mathematician optimization model to support decision-making in order to minimize environmental impacts. Materials and methods: A descriptive study was applied due to the fact that some fundamental characteristics of the studied homogeneous phenomenon are presented and it is also considered to be quasi experimental. The calculation of the model for plants of the department is based on three axes (environmental, economic and social, that are present in the general equation of optimization. Results: A model of harnessing organic solids waste in the techniques of biological treatment of composting aerobic and worm cultivation is obtained, optimizing the system with the emissions savings of greenhouse gases spread into the atmosphere, and in the reduction of the overall cost of final disposal of organic solids waste in sanitary landfill. Based on the economic principle of utility that determines the environmental feasibility and sustainability in the plants of harnessing organic solids waste to the department, organic fertilizers such as compost and humus capture carbon and nitrogen that reduce the tons of CO2.
43rd Aerospace Mechanisms Symposium
Boesiger, Edward A.
2016-01-01
The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms. Sponsored and organized by the Mechanisms Education Association, responsibility for hosting the AMS is shared by the National Aeronautics and Space Administration and Lockheed Martin Space Systems Company (LMSSC). Now in its 43rd symposium, the AMS continues to be well attended, attracting participants from both the U.S. and abroad. The 43rd AMS was held in Santa Clara, California on May 4, 5 and 6, 2016. During these three days, 42 papers were presented. Topics included payload and positioning mechanisms, components such as hinges and motors, CubeSats, tribology, and mechanism testing. Hardware displays during the supplier exhibit gave attendees an opportunity to meet with developers of current and future mechanism components. The high quality of this symposium is a result of the work of many people, and their efforts are gratefully acknowledged. This extends to the voluntary members of the symposium organizing committee representing the eight NASA field centers, LMSSC, and the European Space Agency. Appreciation is also extended to the session chairs, the authors, and particularly the personnel at ARC responsible for the symposium arrangements and the publication of these proceedings. A sincere thank you also goes to the symposium executive committee who is responsible for the year-to-year management of the AMS, including paper processing and preparation of the program. The use of trade names of manufacturers in this publication does not constitute an official endorsement of such products or manufacturers, either expressed or implied, by the National Aeronautics and Space Administration.
Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.
1994-01-01
The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DOD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis the technical communications practices of U.S. aerospace engineers and scientists affiliated with the Society of Automotive Engineers (SAE).
Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.
1995-01-01
The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DOD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis the technical communications practices of U.S. aerospace engineers and scientists who are members of the American Institute of Aeronautics and Astronautics (AIAA).
Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.
1994-01-01
The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DOD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis U.S. aerospace engineering faculty and students.
Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.
1994-01-01
The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DoD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis U.S. aerospace industry librarians and technical information specialists as information intermediaries.
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids
Dai, Fu-Zhi; Zhou, Yanchun
2016-01-01
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials. PMID:27604165
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids
Dai, Fu-Zhi; Zhou, Yanchun
2016-09-01
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials.
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids.
Dai, Fu-Zhi; Zhou, Yanchun
2016-09-08
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials.
Modeling Total Suspended Solids (TSS) Concentrations in Narragansett Bay.
This work covers mechanistic modeling of suspended particulates in estuarine systems with an application to Narragansett Bay, RI. Suspended particles directly affect water clarity and attenuate light in the water column. Water clarity affects both phytoplankton and submerged aqua...
Ignition models and simulation of solid propellant of thermodynamic undersea vehicle
ZHANG Jin-jun; QIAN Zhi-bo; YANG Jie; YAN Ping
2007-01-01
The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is necessary to establish accurate burning models for solid propellants. Based on combustion models using powder tings and two different solid ignition grains, namely star-shaped ignition grains and stuffed ignition grains, a mathematic model of the ignition process of the propulsion system was built.With the help of Matlah, a series of calculations were made to determine the effects of different grains on ignition characteristics. The results show that stuffed ignition grain is best suited to be the ignition grain of a thermodynamic undersea vehicle system.
A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids
Fu-Zhi Dai; Yanchun Zhou
2016-01-01
Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, wh...
Validation of a Solid Rocket Motor Internal Environment Model
Martin, Heath T.
2017-01-01
In a prior effort, a thermal/fluid model of the interior of Penn State University's laboratory-scale Insulation Test Motor (ITM) was constructed to predict both the convective and radiative heat transfer to the interior walls of the ITM with a minimum of empiricism. These predictions were then compared to values of total and radiative heat flux measured in a previous series of ITM test firings to assess the capabilities and shortcomings of the chosen modeling approach. Though the calculated fluxes reasonably agreed with those measured during testing, this exercise revealed means of improving the fidelity of the model to, in the case of the thermal radiation, enable direct comparison of the measured and calculated fluxes and, for the total heat flux, compute a value indicative of the average measured condition. By replacing the P1-Approximation with the discrete ordinates (DO) model for the solution of the gray radiative transfer equation, the radiation intensity field in the optically thin region near the radiometer is accurately estimated, allowing the thermal radiation flux to be calculated on the heat-flux sensor itself, which was then compared directly to the measured values. Though the fully coupling the wall thermal response with the flow model was not attempted due to the excessive computational time required, a separate wall thermal response model was used to better estimate the average temperature of the graphite surfaces upstream of the heat flux gauges and improve the accuracy of both the total and radiative heat flux computations. The success of this modeling approach increases confidence in the ability of state-of-the-art thermal and fluid modeling to accurately predict SRM internal environments, offers corrections to older methods, and supplies a tool for further studies of the dynamics of SRM interiors.
Ndanou, S., E-mail: serge.ndanou@univ-amu.fr; Favrie, N., E-mail: nicolas.favrie@univ-amu.fr; Gavrilyuk, S., E-mail: sergey.gavrilyuk@univ-amu.fr
2015-08-15
We extend the model of diffuse solid–fluid interfaces developed earlier by authors of this paper to the case of arbitrary number of interacting hyperelastic solids. Plastic transformations of solids are taken into account through a Maxwell type model. The specific energy of each solid is given in separable form: it is the sum of a hydrodynamic part of the energy depending only on the density and the entropy, and an elastic part of the energy which is unaffected by the volume change. It allows us to naturally pass to the fluid description in the limit of vanishing shear modulus. In spite of a large number of governing equations, the model has a quite simple mathematical structure: it is a duplication of a single visco-elastic model. The model is well posed both mathematically and thermodynamically: it is hyperbolic and compatible with the second law of thermodynamics. The resulting model can be applied in the situations involving an arbitrary number of fluids and solids. In particular, we show the ability of the model to describe spallation and penetration phenomena occurring during high velocity impacts.
Fluid-solid interaction model for hydraulic reciprocating O-ring seals
Liao, Chuanjun; Huang, Weifeng; Wang, Yuming; Suo, Shuangfu; Liu, Ying
2013-01-01
Elastohydrodynamic lubrication characteristics of hydraulic reciprocating seals have significant effects on sealing and tribology performances of hydraulic actuators, especially in high parameter hydraulic systems. Only elastic deformations of hydraulic reciprocating seals were discussed, and hydrodynamic effects were neglected in many studies. The physical process of the fluid-solid interaction effect did not be clearly presented in the existing fluid-solid interaction models for hydraulic reciprocating O-ring seals, and few of these models had been simultaneously validated through experiments. By exploring the physical process of the fluid-solid interaction effect of the hydraulic reciprocating O-ring seal, a numerical fluid-solid interaction model consisting of fluid lubrication, contact mechanics, asperity contact and elastic deformation analyses is constructed with an iterative procedure. With the SRV friction and wear tester, the experiments are performed to investigate the elastohydrodynamic lubrication characteristics of the O-ring seal. The regularity of the friction coefficient varying with the speed of reciprocating motion is obtained in the mixed lubrication condition. The experimental result is used to validate the fluid-solid interaction model. Based on the model, The elastohydrodynamic lubrication characteristics of the hydraulic reciprocating O-ring seal are presented respectively in the dry friction, mixed lubrication and full film lubrication conditions, including of the contact pressure, film thickness, friction coefficient, liquid film pressure and viscous shear stress in the sealing zone. The proposed numerical fluid-solid interaction model can be effectively used to analyze the operation characteristics of the hydraulic reciprocating O-ring seal, and can also be widely used to study other hydraulic reciprocating seals.
A General Mechanistic Model of Solid Oxide Fuel Cells
SHI Yixiang; CAI Ningsheng
2006-01-01
A comprehensive model considering all forms of polarization was developed. The model considers the intricate interdependency among the electrode microstructure, the transport phenomena, and the electrochemical processes. The active three-phase boundary surface was expressed as a function of electrode microstructure parameters (porosity, coordination number, contact angle, etc.). The exchange current densities used in the simulation were obtained by fitting a general formulation to the polarization curves proposed as a function of cell temperature and oxygen partial pressure. A validation study shows good agreement with published experimental data. Distributions of overpotentials, gas component partial pressures, and electronic/ionic current densities have been calculated. The effects of a porous electrode structure and of various operation conditions on cell performance were also predicted. The mechanistic model proposed can be used to interpret experimental observations and optimize cell performance by incorporating reliable experimental data.
Modeling of an Adjustable Beam Solid State Light Project
Clark, Toni
2015-01-01
This proposal is for the development of a computational model of a prototype variable beam light source using optical modeling software, Zemax Optics Studio. The variable beam light source would be designed to generate flood, spot, and directional beam patterns, while maintaining the same average power usage. The optical model would demonstrate the possibility of such a light source and its ability to address several issues: commonality of design, human task variability, and light source design process improvements. An adaptive lighting solution that utilizes the same electronics footprint and power constraints while addressing variability of lighting needed for the range of exploration tasks can save costs and allow for the development of common avionics for lighting controls.
A Model for Deformation and Fragmentation in Crushable Brittle Solids
2008-03-01
910. [13] Bažant ZP, Caner FC, Carol I, Adley MD, Akers SA. Microplane model M4 for concrete. I. formulation with work-conjugate deviatoric stress...ASCE J Eng Mech 2000;126:944–53. [14] Asaro RJ. Crystal plasticity. ASME J Appl Mech 1983;50:921–34. [15] Bažant ZP, Caner FC, Adley MD, Akers SA...Fracturing rate effect and creep in microplane model for dynamics. ASCE J Eng Mech 2000;126:962–70. [16] Bažant ZP, Adley MD, Caner FC, Carol I, Jirásek
Samadi, Sara; Vaziri, Behrooz Mahmoodzadeh
2017-07-14
Solid extraction process, using the supercritical fluid, is a modern science and technology, which has come in vogue regarding its considerable advantages. In the present article, a new and comprehensive model is presented for predicting the performance and separation yield of the supercritical extraction process. The base of process modeling is partial differential mass balances. In the proposed model, the solid particles are considered twofold: (a) particles with intact structure, (b) particles with destructed structure. A distinct mass transfer coefficient has been used for extraction of each part of solid particles to express different extraction regimes and to evaluate the process accurately (internal mass transfer coefficient was used for the intact-structure particles and external mass transfer coefficient was employed for the destructed-structure particles). In order to evaluate and validate the proposed model, the obtained results from simulations were compared with two series of available experimental data for extraction of chamomile extract with supercritical carbon dioxide, which had an excellent agreement. This is indicative of high potentiality of the model in predicting the extraction process, precisely. In the following, the effect of major parameters on supercritical extraction process, like pressure, temperature, supercritical fluid flow rate, and the size of solid particles was evaluated. The model can be used as a superb starting point for scientific and experimental applications. Copyright © 2017 Elsevier B.V. All rights reserved.
The 1990 NASA Aerospace Battery Workshop
Kennedy, Lewis M. (Compiler)
1991-01-01
This document contains the proceedings of the 21st annual NASA Aerospace Battery Workshop, hosted by the Marshall Space Flight Center on December 4-6, 1990. The workshop was attended by scientists and engineers from various agencies of the U.S. Government, aerospace contractors, and battery manufacturers as well as participation in like kind from the European Space Agency member nations. The subjects covered included nickel-cadmium, nickel-hydrogen, silver-zinc, lithium based chemistries, and advanced technologies as they relate to high reliability operations in aerospace applications.
Titanium alloys Russian aircraft and aerospace applications
Moiseyev, Valentin N
2005-01-01
This text offers previously elusive information on state-of-the-art Russian metallurgic technology of titanium alloys. It details their physical, mechanical, and technological properties, as well as treatments and applications in various branches of modern industry, particularly aircraft and aerospace construction. Titanium Alloys: Russian Aircraft and Aerospace Applications addresses all facets of titanium alloys in aerospace and aviation technology, including specific applications, fundamentals, composition, and properties of commercial alloys. It is useful for all students and researchers interested in the investigation and applications of titanium.
NASA biomedical applications team. Applications of aerospace technology in biology and medicine
Rouse, D. J.; Beadles, R.; Beall, H. C.; Brown, J. N., Jr.; Clingman, W. H.; Courtney, M. W.; Mccartney, M.; Scearce, R. W.; Wilson, B.
1979-01-01
The use of a bipolar donor-recipient model of medical technology transfer is presented. That methodology is designed to: (1) identify medical problems and aerospace technology that in combination constitute opportunities for successful medical products; (2) obtain the early participation of industry in the transfer process; and (3) obtain acceptance by the medical community of new medical products based on aerospace technology. Problem descriptions and activity reports and the results of a market study on the tissue freezing device are presented.
Advanced Breakdown Modeling for Solid-State Circuit Design
Milovanović, V.
2010-01-01
Modeling of the effects occurring outside the usual region of application of semiconductor devices is becoming more important with increasing demands set upon electronic systems for simultaneous speed and output power. Analog integrated circuit designers are forced to enter regimes of transistor ope
Electrochemical Impedance Modeling of a Solid Oxide Fuel Cell Anode
Mohammadi, R.; Søgaard, Martin; Ramos, Tania
2014-01-01
(TLM), which is suitably modified to account for the electrode microstructural details, is used for modeling the impedance arising from the electrochemical reactions. In order to solve the system of nonlinear equations, an in-house code based on the finite difference method was developed. Some...
Output Feedback M-MRAC Backstepping With Aerospace Applications
Stepanyan, Vahram; Krishnakumar, Kalmanje Sriniva
2014-01-01
The paper presents a certainty equivalence output feedback backstepping adaptive control design method for the systems of any relative degree with unmatched uncertainties without over-parametrization. It uses a fast prediction model to estimate the unknown parameters, which is independent of the control design. It is shown that the system's input and output tracking errors can be systematically decreased by the proper choice of the design parameters. The approach is applied to aerospace control problems and tested in numerical simulations.
Patisson, F
2005-09-15
Gas-solid reactions control a great number of major industrial processes involving matter transformation. This dissertation aims at showing that mathematical modelling is a useful tool for both understanding phenomena and optimising processes. First, the physical processes associated with a gas-solid reaction are presented in detail for a single particle, together with the corresponding available kinetic grain models. A second part is devoted to the modelling of multiparticle reactors. Different approaches, notably for coupling grain models and reactor models, are illustrated through various case studies: coal pyrolysis in a rotary kiln, production of uranium tetrafluoride in a moving bed furnace, on-grate incineration of municipal solid wastes, thermogravimetric apparatus, nuclear fuel making, steel-making electric arc furnace. (author)
76 FR 1600 - U.S. Aerospace Supplier & Investment Mission
2011-01-11
... International Trade Administration U.S. Aerospace Supplier & Investment Mission AGENCY: International Trade.... Aerospace Supplier & Investment Mission to Montreal, Canada on May 2-4, 2011. This aerospace mission is an ] ideal opportunity for U.S. aerospace companies to gain valuable international business leads in a...
75 FR 39911 - Aerospace Supplier Development Mission to China
2010-07-13
... International Trade Administration Aerospace Supplier Development Mission to China AGENCY: International Trade... Aerospace Supplier Development Mission to China from November 7-17, 2010. The 2010 Aerospace Supplier... industry. It is intended to include representatives from a variety of U.S. aerospace industry...
Model for solid oxide fuel cell cathodes prepared by infiltration
Samson, Alfred Junio; Søgaard, Martin; Hendriksen, Peter Vang
2017-01-01
A 1-dimensional model of a cathode has been developed in order to understand and predict the performance of cathodes prepared by infiltration of La0.6Sr0.4Co1.05O3-Î´ (LSC) into porous backbones of Ce0.9Gd0.1O1.95 (CGO). The model accounts for the mixed ionic and electronic conductivity of LSC......, ionic conductivity of CGO, gas transport in the porous cathode, and the oxygen reduction reaction at the surface of percolated LSC. Geometrical variations are applied to reflect a changing microstructure of LSC under varying firing temperatures. Using microstructural parameters obtained from detailed...... parameter variations are presented and discussed with the aim of presenting specific guidelines for optimizing the microstructure of cathodes prepared by infiltration....
A Basis for Solid Modeling of Gear Teeth with Application in Design and Manufacture
Huston, Ronald L.; Mavriplis, Dimitrios; Oswald, Fred B.; Liu, Yung Sheng
1994-01-01
This paper discusses a new approach to modeling gear tooth surfaces. A computer graphics solid modeling procedure is used to simulate the tooth fabrication processes. This procedure is based on the principles of differential geometry that pertain to envelopes of curves and surfaces. The procedure is illustrated with the modeling of spur, helical, bevel, spiral bevel and hypoid gear teeth. Applications in design and manufacturing arc discussed. Extensions to nonstandard tooth forms, to cams, and to rolling element hearings are proposed.
Computational multiscale modeling of fluids and solids theory and applications
Steinhauser, Martin Oliver
2017-01-01
The idea of the book is to provide a comprehensive overview of computational physics methods and techniques, that are used for materials modeling on different length and time scales. Each chapter first provides an overview of the basic physical principles which are the basis for the numerical and mathematical modeling on the respective length-scale. The book includes the micro-scale, the meso-scale and the macro-scale, and the chapters follow this classification. The book explains in detail many tricks of the trade of some of the most important methods and techniques that are used to simulate materials on the perspective levels of spatial and temporal resolution. Case studies are included to further illustrate some methods or theoretical considerations. Example applications for all techniques are provided, some of which are from the author’s own contributions to some of the research areas. The second edition has been expanded by new sections in computational models on meso/macroscopic scales for ocean and a...
A multiscale model of distributed fracture and permeability in solids in all-round compression
De Bellis, Maria Laura; Ortiz, Michael; Pandolfi, Anna
2016-01-01
We present a microstructural model of permeability in fractured solids, where the fractures are described in terms of recursive families of parallel, equidistant cohesive faults. Faults originate upon the attainment of a tensile or shear resistance in the undamaged material. Secondary faults may form in a hierarchical orga- nization, creating a complex network of connected fractures that modify the permeability of the solid. The undamaged solid may possess initial porosity and permeability. The particular geometry of the superposed micro-faults lends itself to an explicit analytical quantification of the porosity and permeability of the dam- aged material. The approach is particularly appealing as a means of modeling low permeability oil and gas reservoirs stimulated by hydraulic fracturing.
CO2 Absorption in a Lab-Scale Fixed Solid Bed Reactor: Modelling and Experimental Tests
Roberto Gabbrielli
2004-09-01
Full Text Available The CO2 absorption in a lab-scale fixed solid bed reactor filled with different solid sorbents has been studied under different operative conditions regarding temperature (20-200°C and input gas composition (N2, O2, CO2, H2O at 1bar pressure. The gas leaving the reactor has been analysed to measure the CO2 and O2 concentrations and, consequently, to evaluate the overall CO2 removal efficiency. In order to study the influence of solid sorbent type (i.e. CaO, coal bottom ash, limestone and blast furnace slag and of mass and heat transfer processes on CO2 removal efficiency, a one-dimensional time dependent mathematical model of the reactor, which may be considered a Plug Flow Reactor, has been developed. The quality of the model has been confirmed using the experimental results.
Scaling laws for gas-solid riser flow through two-fluid model simulation
P.R. Naren; Vivek. V. Ranade
2011-01-01
Scale up of gas-solid circulating fluidized bed (CFB) risers poses many challenges to researchers. In this paper, CFD investigation of hydrodynamic scaling laws for gas-solid riser flow was attempted on the basis of two-fluid model simulations, in particular, the recently developed empirical scaling law of Qi, Zhu,and Huang (2008). A 3D computational model with periodic boundaries was used to perform numerical experiments and to study the effect of various system and operating parameters in hydrodynamic scaling of riser flow. The Qi scaling ratio was found to ensure similarity in global parameters like overall crosssectional average solid holdup or pressure drop gradient. However, similarity in local flow profiles was not observed for all the test cases. The present work also highlighted the significance of error bars in reporting experimental values.
Tretyakov, Nikita; Müller, Marcus; Todorova, Desislava; Thiele, Uwe
2013-02-14
We study equilibrium properties of polymer films and droplets on a solid substrate employing particle-based simulation techniques (molecular dynamics) and a continuum description. Parameter-passing techniques are explored that facilitate a detailed comparison of the two models. In particular, the liquid-vapor, solid-liquid, and solid-vapor interface tensions, and the Derjaguin or disjoining pressure are determined by molecular dynamics simulations. This information is then introduced into continuum descriptions accounting for (i) the full curvature and (ii) a long-wave approximation of the curvature (thin film model). A comparison of the dependence of the contact angle on droplet size indicates that the theories agree well if the contact angles are defined in a compatible manner.
Sébastien Calvo
2013-01-01
Full Text Available In this work, we study the conditions needed to reach homogeneous distribution of aluminium salts particles in water inside a torispherical bottom shaped stirred tank of 70 L equipped with a Pfaudler RCI type impeller and three equispaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is used afterwards to develop scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. Sliding Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics is simulated independently using the well-known k-∊ turbulence model. The liquid-solid mixture behaviour is then described by implementing the Eulerian Mixture model. Computed liquid velocity fields are validated by comparison with PIV measurements. Computed Nhs were found to be in good agreement with experimental measurements. Results from different scales allowed correlating Nhs values to the volumetric power consumption.
A multiscale model of distributed fracture and permeability in solids in all-round compression
De Bellis, Maria Laura; Della Vecchia, Gabriele; Ortiz, Michael; Pandolfi, Anna
2017-07-01
We present a microstructural model of permeability in fractured solids, where the fractures are described in terms of recursive families of parallel, equidistant cohesive faults. Faults originate upon the attainment of tensile or shear strength in the undamaged material. Secondary faults may form in a hierarchical organization, creating a complex network of connected fractures that modify the permeability of the solid. The undamaged solid may possess initial porosity and permeability. The particular geometry of the superposed micro-faults lends itself to an explicit analytical quantification of the porosity and permeability of the damaged material. The model is the finite kinematics version of a recently proposed porous material model, applied with success to the simulation of laboratory tests and excavation problems [De Bellis, M. L., Della Vecchia, G., Ortiz, M., Pandolfi, A., 2016. A linearized porous brittle damage material model with distributed frictional-cohesive faults. Engineering Geology 215, 10-24. Cited By 0. 10.1016/j.enggeo.2016.10.010]. The extension adds over and above the linearized kinematics version for problems characterized by large deformations localized in narrow zones, while the remainder of the solid undergoes small deformations, as typically observed in soil and rock mechanics problems. The approach is particularly appealing as a means of modeling a wide scope of engineering problems, ranging from the prevention of water or gas outburst into underground mines, to the prediction of the integrity of reservoirs for CO2 sequestration or hazardous waste storage, to hydraulic fracturing processes.
Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes
García-Gen, Santiago [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Sousbie, Philippe; Rangaraj, Ganesh [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France); Lema, Juan M. [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Rodríguez, Jorge, E-mail: jrodriguez@masdar.ac.ae [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Institute Centre for Water and Environment (iWater), Masdar Institute of Science and Technology, PO Box 54224 Abu Dhabi (United Arab Emirates); Steyer, Jean-Philippe; Torrijos, Michel [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France)
2015-01-15
Highlights: • Fractionation of solid wastes into readily and slowly biodegradable fractions. • Kinetic coefficients estimation from mono-digestion batch assays. • Validation of kinetic coefficients with a co-digestion continuous experiment. • Simulation of batch and continuous experiments with an ADM1-based model. - Abstract: A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 g VS/L d. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes.
Models for solid-state transport: messenger RNA movement from nucleus to cytoplasm.
Agutter, P S
1994-09-01
This paper explores the idea that mRNAs are transported between their transcription and processing sites in the nucleus, and their translation and degradation sites in the cytoplasm, by a 'solid-state' process. The underlying assumption is that negligible quantities of mRNA and of mRNA precursors are in solution in vivo. Therefore, mRNA transport cannot be considered as movement in the aqueous phase of the cell. The main lines of experimental evidence supporting this 'solid-state' concept are summarized and related controversies are outlined. Three possible models for a solid-state transport mechanism are discussed: a direct transfer model, with receptors organized analogously to the components of a multienzyme complex; a motor-driven model, analogous to synaptic vesicle transport in axons; and an assembly-driven model which assumes net movement along a fibril resulting from differential activities at the poles. Qualitative evaluation indicates that each of these models has characteristic advantages and disadvantages. The possibility that other nucleocytoplasmic transport processes might operate by solid-state mechanisms is briefly discussed.
Modelling the processing of aluminium alloys in the semi-solid state
Wahlen, A. [ARC Leichtmetallkompetenzzentrum Ranshofen GmbH, Ranshofen (Austria)
2002-07-01
Thixoforming, an innovative technique in which metals are formed in their semi-solid state, permits the cost-efficient production of components with improved properties and performance compared to conventional pressure die casting. Since this process is still relatively new, great technical advances can be expected in the near future. These advances should allow production of near-net-shape components with good mechanical properties, combined with low manufacturing cost. Due to the distinct thixotropic flow pattern of the semi-solid slurry, high production speeds similar to those of conventional pressure die casting can be achieved, yet the disadvantages of the latter are eliminated: thixoformed components possess a good combination of strength and ductility, and they are heat-treatable and weldable. The requirement for thixotropic flow behaviour is a particular microstructure in the semi-solid state. At the onset of forming, the solid phase of the material must exhibit a globular morphology, a feature that can be produced with a novel casting technique called new rheocasting (NRC). Cast billets of several aluminium alloys and resulting microstructures show the feasibility of the chosen process variant. Constitutive models for the distinct flow behaviour of thixotropic aluminium alloys in the semi-solid state are derived with respect to temperature, strain rate and microstructure. Experimental techniques such as deformation tests, backward extrusion experiments, differential thermal analysis and quantitative metallurgy provide the necessary data to calibrate the materials models. For the implementation in a special-purpose FE software package, constitutive models for the thixotropic flow stress, the specific thixotropic flow stress, the specific heat capacity and the thermal conductivity of cast and wrought aluminium alloys in the semi-solid state are provided. For the optimization of the thixoforming manufacturing process these models were implemented in the FE
BIOLEACH: Coupled modeling of leachate and biogas production on solid waste landfills
Rodrigo-Clavero, Maria-Elena; Rodrigo-Ilarri, Javier
2015-04-01
One of the most important factors to address when performing the environmental impact assessment of urban solid waste landfills is to evaluate the leachate production. Leachate management (collection and treatment) is also one of the most relevant economical aspects to take into account during the landfill life. Leachate is formed as a solution of biological and chemical components during operational and post-operational phases on urban solid waste landfills as a combination of different processes that involve water gains and looses inside the solid waste mass. Infiltration of external water coming from precipitation is the most important component on this water balance. However, anaerobic waste decomposition and biogas formation processes play also a role on the balance as water-consuming processes. The production of leachate one biogas is therefore a coupled process. Biogas production models usually consider optimal conditions of water content on the solid waste mass. However, real conditions during the operational phase of the landfill may greatly differ from these optimal conditions. In this work, the first results obtained to predict both the leachate and the biogas production as a single coupled phenomenon on real solid waste landfills are shown. The model is applied on a synthetic case considering typical climatological conditions of Mediterranean catchments.
Injection Performance of a Gas-Solid Injector Based on the Particle Trajectory Model
Daolong Yang
2015-01-01
Full Text Available Gas-solid injectors are widely used feeding equipment in pneumatic conveying systems. The performance of a gas-solid injector has a significant influence on the type of application it can be employed for. To determine the key factors influencing the injection performance and address clogging problems in a gas-solid injector during a pneumatic conveying process, the particle trajectory model has been utilised as a means to perform simulations. In the particle trajectory model, the gas phase is treated as a continuous medium and the particle phase is treated as a dispersed phase. In this work, numerical and experimental studies were conducted for different nozzle positions in a gas-solid injector. A gas-solid injector test-bed was constructed based on the results of the simulations. The results show that the nozzle position is the key factor that affects the injection performance. The number of extrusive particles first increases and then decreases with the change in the nozzle position from left to right. Additionally, there is an optimum nozzle position that maximises the injection mass and minimises the number of particles remaining in the hopper. Based on the results of this work, the injection performance can be significantly increased and the clogging issues are effectively eliminated.
Kinetic study of solid waste pyrolysis using distributed activation energy model.
Bhavanam, Anjireddy; Sastry, R C
2015-02-01
The pyrolysis characteristics of municipal solid waste, agricultural residues such as ground nut shell, cotton husk and their blends are investigated using non-isothermal thermogravimetric analysis (TGA) with in a temperature range of 30-900 °C at different heating rates of 10 °C, 30 °C and 50 °C/min in inert atmosphere. From the thermograms obtained from TGA, it is observed that the maximum rate of degradation occurred in the second stage of the pyrolysis process for all the solid wastes. The distributed activation energy model (DAEM) is used to study the pyrolysis kinetics of the solid wastes. The kinetic parameters E (activation energy), k0 (frequency factor) are calculated from this model. It is found that the range of activation energies for agricultural residues are lower than the municipal solid waste. The activation energies for the municipal solid waste pyrolysis process drastically decreased with addition of agricultural residues. The proposed DAEM is successfully validated with TGA experimental data. Copyright © 2014 Elsevier Ltd. All rights reserved.
Bed models for solid fuel conversion process in grate-fired boilers
Costa, M.; Massarotti, N.; Indrizzi, V.
2013-01-01
to describe the thermo-chemical conversion process of a solid fuel bed in a grate-fired boiler is presented. In this work both models consider the incoming solid fuel as subjected to drying, pyrolysis, gasification and combustion. In the first approach the biomass bed is treated as a 0D system, but the thermo......Because of the complexity to describe and solve thermo-chemical processes occurring in a fuel bed in grate-fired boiler, it is often necessary to simplify the process and use modeling techniques based on overall mass, energy and species conservation. A comparison between two numerical models......-chemical processes are divided in two successive sections: drying and conversion (which includes pyrolysis, gasification and combustion). The second model is an empirical 1D approach. The two models need input data such as composition, temperature and feeding rate of biomass and primary air. Temperature, species...
Additive Manufacturing of Aerospace Propulsion Components
Misra, Ajay K.; Grady, Joseph E.; Carter, Robert
2015-01-01
The presentation will provide an overview of ongoing activities on additive manufacturing of aerospace propulsion components, which included rocket propulsion and gas turbine engines. Future opportunities on additive manufacturing of hybrid electric propulsion components will be discussed.
Autoclaves for Aerospace Applications: Issues and Challenges
A. R. Upadhya
2011-01-01
Full Text Available The Council of Scientific and Industerial Research National Aerospace Laboratories (CSIR-NAL, Bangalore, India has been engaged in the research of autoclaves for the past three decades and has pioneered their development and usage in India for aerospace/aircraft structural applications. The autoclaves at CSIR-NAL have played a significant role in all the major national aircraft/aerospace programs. The largest aerospace autoclave in India (working size of 4.4 m diameter and 9.0 m length has been successfully commissioned at CSIR-NAL. This paper gives the technological challenges faced and the innovative concepts that were introduced in these autoclaves.
Aerospace Grade Carbon Felt Preform Project
National Aeronautics and Space Administration — Fiber Materials, Inc. (FMI) will develop an aerospace-grade carbon felt preform by employing application specific materials with effective processes and fabrication...
Mass transfer inside oblate spheroidal solids: modelling and simulation
J. E. F. Carmo
2008-03-01
Full Text Available A numerical solution of the unsteady diffusion equation describing mass transfer inside oblate spheroids, considering a constant diffusion coefficient and the convective boundary condition, is presented. The diffusion equation written in the oblate spheroidal coordinate system was used for a two-dimensional case. The finite-volume method was employed to discretize the basic equation. The linear equation set was solved iteratively using the Gauss-Seidel method. As applications, the effects of the Fourier number, the Biot number and the aspect ratio of the body on the drying rate and moisture content during the process are presented. To validate the methodology, results obtained in this work are compared with analytical results of the moisture content encountered in the literature and good agreement was obtained. The results show that the model is consistent and it may be used to solve cases such as those that include disks and spheres and/or those with variable properties with small modifications.
Dynamic density functional theory of solid tumor growth: Preliminary models
Arnaud Chauviere
2012-03-01
Full Text Available Cancer is a disease that can be seen as a complex system whose dynamics and growth result from nonlinear processes coupled across wide ranges of spatio-temporal scales. The current mathematical modeling literature addresses issues at various scales but the development of theoretical methodologies capable of bridging gaps across scales needs further study. We present a new theoretical framework based on Dynamic Density Functional Theory (DDFT extended, for the first time, to the dynamics of living tissues by accounting for cell density correlations, different cell types, phenotypes and cell birth/death processes, in order to provide a biophysically consistent description of processes across the scales. We present an application of this approach to tumor growth.
Modeling and Structural Optimization of Solid Oxide Fuel Cells
Panagakos, Grigorios
The research conducted in the context of this PhD, lies on the cross section between multi-scale modeling of flow in porous media, electrochemical diffusion and reaction, in combination with Shape and Structural Optimization techniques. More specifi-cally, we have followed two lines of action...... requirements. On the one hand, it needs to secure the intake of fuel into the cell, fact that would require an as low hydraulic resistance as possible, i.e. ideally an open channel and on the other hand to exhibit an as high as possible electronic conductance, which in the ideal case would mean an area blocked...... completely by a material with high conductivity such as coated stainless steel. The balance between these two competing, oppositely driving forces, indicate that there should be a design that satisfies in the best way both. Similar problems have been successfully dealt by structural-topology optimization...
Probability and Statistics in Aerospace Engineering
Rheinfurth, M. H.; Howell, L. W.
1998-01-01
This monograph was prepared to give the practicing engineer a clear understanding of probability and statistics with special consideration to problems frequently encountered in aerospace engineering. It is conceived to be both a desktop reference and a refresher for aerospace engineers in government and industry. It could also be used as a supplement to standard texts for in-house training courses on the subject.
Introduction to NASA's Academy of Aerospace Quality
Smith, Alice; Smith, Jeffrey
2016-01-01
The NASA Academy of Aerospace Quality (AAQ) is an internet-based public domain forum of quality assurance-related educational modules for students and faculty at academic institutions targeting those involved in aerospace research, technology development, and payload design and development including Cube Sats, Small Sats, Nano Sats, Rockets and High Altitude Balloons. The target users are university project and research teams but the academy has also been used by K-12 teams, independent space...
Novel Wiring Technologies for Aerospace Applications
Gibson, Tracy L.; Parrish, Lewis M.
2014-01-01
Because wire failure in aerospace vehicles could be catastrophic, smart wiring capabilities have been critical for NASA. Through the years, researchers at Kennedy Space Center (KSC) have developed technologies, expertise, and research facilities to meet this need. In addition to aerospace applications, NASA has applied its knowledge of smart wiring, including self-healing materials, to serve the aviation industry. This webinar will discuss the development efforts of several wiring technologies at KSC and provide insight into both current and future research objectives.
Solid waste integrated cost analysis model: 1991 project year report. Part 2
1991-12-31
The purpose of the City of Houston`s 1991 Solid Waste Integrated Cost Analysis Model (SWICAM) project was to continue the development of a computerized cost analysis model. This model is to provide solid waste managers with tool to evaluate the dollar cost of real or hypothetical solid waste management choices. Those choices have become complicated by the implementation of Subtitle D of the Resources Conservation and Recovery Act (RCRA) and the EPA`s Integrated Approach to managing municipal solid waste;. that is, minimize generation, maximize recycling, reduce volume (incinerate), and then bury (landfill) only the remainder. Implementation of an integrated solid waste management system involving all or some of the options of recycling, waste to energy, composting, and landfilling is extremely complicated. Factors such as hauling distances, markets, and prices for recyclable, costs and benefits of transfer stations, and material recovery facilities must all be considered. A jurisdiction must determine the cost impacts of implementing a number of various possibilities for managing, handling, processing, and disposing of waste. SWICAM employs a single Lotus 123 spreadsheet to enable a jurisdiction to predict or assess the costs of its waste management system. It allows the user to select his own process flow for waste material and to manipulate the model to include as few or as many options as he or she chooses. The model will calculate the estimated cost for those choices selected. The user can then change the model to include or exclude waste stream components, until the mix of choices suits the user. Graphs can be produced as a visual communication aid in presenting the results of the cost analysis. SWICAM also allows future cost projections to be made.
Asymptotic Analysis in a Gas-Solid Combustion Model with Pattern Formation
Claude-Michel BRAUNER; Lina HU; Luca LORENZI
2013-01-01
The authors consider a free interface problem which stems from a gas-solid model in combustion with pattern formation.A third-order,fully nonlinear,self-consistent equation for the flame front is derived.Asymptotic methods reveal that the interface approaches a solution to the Kuramoto-Sivashinsky equation.Numerical results which illustrate the dynamics are presented.
Espinoza, D. N.; Vandamme, M.; Dangla, P.; Pereira, J.-M.; Vidal-Gilbert, S.
2013-12-01
Understanding the adsorption-induced swelling in coal is critical for predictable and enhanced coal bed methane production. The coal matrix is a natural anisotropic disordered microporous solid. We develop an elastic transverse isotropic poromechanical model for microporous solids which couples adsorption and strain through adsorption stress functions and expresses the adsorption isotherm as a multivariate function depending on fluid pressure and solid strains. Experimental data from the literature help invert the anisotropic adsorptive-mechanical properties of Brzeszcze coal samples exposed to CO2. The main findings include the following: (1) adsorption-induced swelling can be modeled by including fluid-specific and pressure-dependent adsorption stress functions into equilibrium equations, (2) modeling results suggest that swelling anisotropy is mostly caused by anisotropy of the solid mechanical properties, and (3) the total amount of adsorbed gas measured by immersing coal in the adsorbate overestimates adsorption amount compared to in situ conditions up to ˜20%. The developed fully coupled model can be upscaled to determine the coal seam permeability through permeability-stress relationships.
Meeuwse, P.; Klok, A.J.; Haemers, S.; Tramper, J.; Rinzema, A.
2012-01-01
Microbial lipids are an interesting feedstock for biodiesel. Their production from agricultural waste streams by fungi cultivated in solid-state fermentation may be attractive, but the yield of this process is still quite low. In this article, a mechanistic model is presented that describes growth,
Modelling fungal solid-state fermentation: The role of inactivation kinetics
Smits, J.P.; Sonsbeek, H.M. van; Knol, W.; Tramper, J.; Geelhoed, W.; Peeters, M.; Rinzema, A.
1999-01-01
The theoretical mathematical models described in this paper are used to evaluate the effects of fungal biomass inactivation kinetics on a non- isothermal tray solid-state fermentation (SSF). The inactivation kinetics, derived from previously reported experiments done under isothermal conditions and
Modeling the Ballistic Behavior of Solid Ejecta from the Deep Impact Cratering Event
Richardson, J. E.; Melosh, H. J.
2006-03-01
We describe results from a forward model of the first-order, solid ejecta particle behavior from the impact produced by the Deep Impact mission. The expansion rate of the plume places constraints on the gravity field, mass, and density of Tempel 1.
Numerical Simulation of Dense Gas-Solid Fluidized Beds: A Multiscale Modeling Strategy
Hoef, van der M.A.; Sint Annaland, van M.; Deen, N.G.; Kuipers, J.A.M.
2008-01-01
Gas-solid fluidized beds are widely applied in many chemical processes involving physical and/or chemical transformations, and for this reason they are the subject of intense research in chemical engineering science. Over the years, researchers have developed a large number of numerical models of ga
IMPROVED SUBGRID SCALE MODEL FOR DENSE TURBULENT SOLID-LIQUID TWO-PHASE FLOWS
TANG Xuelin; QIAN Zhongdong; WU Yulin
2004-01-01
The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules. Assuming that the solid-phase velocity distributions obey the Maxwell equations, the collision term for particles under dense two-phase flow conditions is also derived.In comparison with the governing equations of a dilute two-phase flow, the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations. Based on Cauchy-Helmholtz theorem and Smagorinsky model,a second-order dynamic sub-grid-scale (SGS) model, in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor, is proposed to model the two-phase governing equations by applying dimension analyses. Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls, the velocity and pressure fields, and the volumetric concentration are calculated. The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.
Gervais, C.; Grimbergen, R.F.P.; Markovits, I.; Ariaans, G.J.A.; Kaptein, B.; Bruggink, A.; Broxterman, Q.B.
2004-01-01
The possibility of solid solution behavior of diastereomeric salts, containing multiple resolving agents of the same family (Dutch Resolution), is predicted by molecular modeling. Super-cells containing different ratios of resolving agents in the diastereomeric salt are constructed and optimized, an
Extended GTST-MLD for aerospace system safety analysis.
Guo, Chiming; Gong, Shiyu; Tan, Lin; Guo, Bo
2012-06-01
The hazards caused by complex interactions in the aerospace system have become a problem that urgently needs to be settled. This article introduces a method for aerospace system hazard interaction identification based on extended GTST-MLD (goal tree-success tree-master logic diagram) during the design stage. GTST-MLD is a functional modeling framework with a simple architecture. Ontology is used to extend the ability of system interaction description in GTST-MLD by adding the system design knowledge and the past accident experience. From the level of functionality and equipment, respectively, this approach can help the technician detect potential hazard interactions. Finally, a case is used to show the method.
Optimal control with aerospace applications
Longuski, James M; Prussing, John E
2014-01-01
Want to know not just what makes rockets go up but how to do it optimally? Optimal control theory has become such an important field in aerospace engineering that no graduate student or practicing engineer can afford to be without a working knowledge of it. This is the first book that begins from scratch to teach the reader the basic principles of the calculus of variations, develop the necessary conditions step-by-step, and introduce the elementary computational techniques of optimal control. This book, with problems and an online solution manual, provides the graduate-level reader with enough introductory knowledge so that he or she can not only read the literature and study the next level textbook but can also apply the theory to find optimal solutions in practice. No more is needed than the usual background of an undergraduate engineering, science, or mathematics program: namely calculus, differential equations, and numerical integration. Although finding optimal solutions for these problems is a...
Materials Selection for Aerospace Systems
Arnold, Steven M.; Cebon, David; Ashby, Mike
2012-01-01
A systematic design-oriented, five-step approach to material selection is described: 1) establishing design requirements, 2) material screening, 3) ranking, 4) researching specific candidates and 5) applying specific cultural constraints to the selection process. At the core of this approach is the definition performance indices (i.e., particular combinations of material properties that embody the performance of a given component) in conjunction with material property charts. These material selection charts, which plot one property against another, are introduced and shown to provide a powerful graphical environment wherein one can apply and analyze quantitative selection criteria, such as those captured in performance indices, and make trade-offs between conflicting objectives. Finding a material with a high value of these indices maximizes the performance of the component. Two specific examples pertaining to aerospace (engine blades and pressure vessels) are examined, both at room temperature and elevated temperature (where time-dependent effects are important) to demonstrate the methodology. The discussion then turns to engineered/hybrid materials and how these can be effectively tailored to fill in holes in the material property space, so as to enable innovation and increases in performance as compared to monolithic materials. Finally, a brief discussion is presented on managing the data needed for materials selection, including collection, analysis, deployment, and maintenance issues.
Aerospace Technology Innovation. Volume 10
Turner, Janelle (Editor); Cousins, Liz (Editor); Bennett, Evonne (Editor); Vendette, Joel (Editor); West, Kenyon (Editor)
2002-01-01
Whether finding new applications for existing NASA technologies or developing unique marketing strategies to demonstrate them, NASA's offices are committed to identifying unique partnering opportunities. Through their efforts NASA leverages resources through joint research and development, and gains new insight into the core areas relevant to all NASA field centers. One of the most satisfying aspects of my job comes when I learn of a mission-driven technology that can be spun-off to touch the lives of everyday people. NASA's New Partnerships in Medical Diagnostic Imaging is one such initiative. Not only does it promise to provide greater dividends for the country's investment in aerospace research, but also to enhance the American quality of life. This issue of Innovation highlights the new NASA-sponsored initiative in medical imaging. Early in 2001, NASA announced the launch of the New Partnerships in Medical Diagnostic Imaging initiative to promote the partnership and commercialization of NASA technologies in the medical imaging industry. NASA and the medical imaging industry share a number of crosscutting technologies in areas such as high-performance detectors and image-processing tools. Many of the opportunities for joint development and technology transfer to the medical imaging market also hold the promise for future spin back to NASA.
Aerospace Avionics and Allied Technologies
Jitendra R. Raol
2011-07-01
Full Text Available Avionics is a very crucial and important technology, not only for civil/military aircraft but also for missiles, spacecraft, micro air vehicles (MAVs and unmanned aerial vehicles (UAVs. Even for ground-based vehicles and underwater vehicles (UWVs, avionics is a very important segment of their successful operation and mission accomplishment. The advances in many related and supporting technologies, especially digital electronics, embedded systems, embedded algorithms/software, mobile technology, sensors and instrumentation, computer (network-communication, and realtime operations and simulation, have given a great impetus to the field of avionics. Here, for the sake of encompassing many other applications as mentioned above, the term is used in an expanded sense: Aerospace Avionics (AA, although it is popularly known as Aviation Electronics (or Avionics. However, use of this technology is not limited to aircraft, and hence, we can incorporate all the three types-ground, land, and underwater vehicles-under the term avionics.Defence Science Journal, 2011, 61(4, pp.287-288, DOI:http://dx.doi.org/10.14429/dsj.61.1122
Ward Jones, Sarah E; Chevallier, François G; Paddon, Christopher A; Compton, Richard G
2007-06-01
Theory is presented to describe the voltammetric signals associated with the stripping phase of stripping voltammetry at solid electrodes. Three mathematical models are considered, and the importance of the hemispherical diffusion associated with electrochemical dissolution of particles in the micrometer range is investigated. Model A considers a "monolayer" system where the coverage at a specific point cannot exceed a maximum value. Model B considers a thin layer of metal or metal oxide, but in contrast to model A, the maximum surface coverage is not restricted. Model C represents the stripping of a "thick layer" where the deposition is also unrestricted.
Density-functional theory of a lattice-gas model with vapour, liquid, and solid phases
Prestipino, S.; Giaquinta, P. V.
2003-01-01
We use the classical version of the density-functional theory in the weighted-density approximation to build up the entire phase diagram and the interface structure of a two-dimensional lattice-gas model which is known, from previous studies, to possess three stable phases -- solid, liquid, and vapour. Following the common practice, the attractive part of the potential is treated in a mean-field-like fashion, although with different prescriptions for the solid and the fluid phases. It turns o...
A stochastic model of solid state thin film deposition: Application to chalcopyrite growth
Robert J. Lovelett
2016-04-01
Full Text Available Developing high fidelity quantitative models of solid state reaction systems can be challenging, especially in deposition systems where, in addition to the multiple competing processes occurring simultaneously, the solid interacts with its atmosphere. In this work, we develop a model for the growth of a thin solid film where species from the atmosphere adsorb, diffuse, and react with the film. The model is mesoscale and describes an entire film with thickness on the order of microns. Because it is stochastic, the model allows us to examine inhomogeneities and agglomerations that would be impossible to characterize with deterministic methods. We demonstrate the modeling approach with the example of chalcopyrite Cu(InGa(SeS2 thin film growth via precursor reaction, which is a common industrial method for fabricating thin film photovoltaic modules. The model is used to understand how and why through-film variation in the composition of Cu(InGa(SeS2 thin films arises and persists. We believe that the model will be valuable as an effective quantitative description of many other materials systems used in semiconductors, energy storage, and other fast-growing industries.
Solid Dynamic Models for Analysis of Stress and Strain in Human Hearts
Qiu Guan
2012-01-01
Full Text Available This paper proposes a solid model based on four-dimensional trivariate B-spline for strain and stress analysis of ventricular myocardium. With a series of processing steps in the four-dimensional medical images, the feature points of ventricular inner and outer wall are obtained. A B-spline surface is then used to build the dynamic deformation model of the myocardial walls. With such a surface model, a hexahedron control mesh can be constructed by sweeping the cloud data, and the ventricular solid model is built by fitting the trivariate B-spline parameters. Based on these models, a method of isogeometric analysis can be applied to calculate the stress and strain continuously distributed in the ventricle. The model is represented smoothly in the cylindrical coordinate system and is easy to measure myocardium dynamics for finding abnormal motion. Experiments are carried out for comparing the stress and strain distribution. It is found that the solid model can determine ventricular dynamics which can well reflect the deformation distribution in the heart and imply early clues of cardiac diseases.
Modeling the dynamic process of tsunami earthquake by liquid-solid coupling model
CAI Yon-gen; ZHAO Zhi-dong
2008-01-01
Tsunami induced by earthquake is an interaction problem between liquid and solid. Shallow-water wave equation is often used to modeling the tsunami, and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under sea floor, usually no interaction between them is considered in pure liquid model. In this study, the potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami. For modeling the earthquake, firstly the initial stress field to generate the earthquake is set up, and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside the earthquake fault. It is different from seismic dislocation theory in which the relative slip on the fault is specified in advance. The modeling results reveal that P, SP and the surface wave can be found at the sea surface besides the tsunami wave. The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes, and its maximum amplitude is 0.55 m, which is 2 times as large as that of the sea floor. Tsunami warning information can be taken from the surface wave on the sea surface, which is much earlier than that obtained from the seismograph stations on land. The tsunami speed on the open sea with 3 km depth is 175.8 m/s, which is a little greater than that predicted by long wave theory, (gh)1/2=171.5 m, and its wavelength and amplitude in average are 32 km and 2 m, respectively. After the tsunami propagates to the continental shelf, its speed and wavelength is reduced, but its amplitude become greater, especially, it can elevate up to 10 m and run 55 m forward in vertical and horizontal directions at sea shore, respectively. The maximum vertical accelerations at the epicenter on the sea surface and on the earthquake fault are 5.9 m/2 and 16.5 m/s2, respectively
Computational model and simulations of gas-liquid-solid three-phase interactions
Zhang, Lucy; Wang, Chu
2013-11-01
A computational technique to model three-phase (gas-liquid-solid) interactions is proposed in this study. This numerical algorithm couples a connectivity-free front-tracking method that treats gas-liquid multi-fluid interface to the immersed finite element method that treats fully-coupled fluid-solid interactions. The numerical framework is based on a non-boundary-fitted meshing technique where the background grid is fixed where no mesh-updating or re-meshing is required. An indicator function is used to identify the gas from the liquid, and the fluid (gas or liquid) from the solid. Several 2-D and 3-D validation cases are demonstrated to show the accuracy and the robustness of the method. Funding from NRC and CCNI computational facility at Rensselaer Polytechnic Institute are greatly acknowledged.
Kinetics of solid state phase transformations: Measurement and modelling of some basic issues
S Raju; E Mohandas
2010-01-01
A brief review of the issues involved in modelling of the solid state transformation kinetics is presented. The fact that apart from the standard thermodynamic parameters, certain path variables like heating or cooling rate can also exert a crucial influence on the kinetic outcome is stressed. The kinetic specialties that are intrinsic to phase changes proceeding under varying thermal history are enumerated. A simple and general modelling methodology for understanding the kinetics of non-isothermal transformations is outlined.
Modeling of Proton-Conducting Solid Oxide Fuel Cells Fueled with Syngas
2014-01-01
Solid oxide fuel cells (SOFCs) with proton conducting electrolyte (H-SOFCs) are promising power sources for stationary applications. Compared with other types of fuel cells, one distinct feature of SOFC is their fuel flexibility. In this study, a 2D model is developed to investigate the transport and reaction in an H-SOFC fueled with syngas, which can be produced from conventional natural gas or renewable biomass. The model fully considers the fluid flow, mass transfer, heat transfer and r...
Thermodynamic Perturbation Theory for Solid-Liquid Phase Transition of Lennard-Jones Model
ZHOUShi-Qi; ZHANGXiao-Qi
2004-01-01
Both a free volume approach for Helmholtz free energy and a theoretically-based fitted formula for radial distribution function (rdf) of hard sphere solid are employed to describe the Helmholtz free energy of Lennard-Jones solid in the framework of the first order thermodynamic perturbation theory, which also is employed for the uniform Lennard Jones fluid. The dividing of the Lennard-Jones potential follows from the INCA prescription, but the specification of the equivalent hard sphere diameter is determined by a simple iteration procedure devised originally for liquid state, but extended to solid state in the present study. Two hundred shells are used in the rdf to get an accurate perturbation term.The present approach is very accurate for the description of excess Helmholtz free energy of LJ solid, but shows some deviation from the simulation for excess Helmholtz free energy of uniform LJ fluid when the reduced temperature kT/ε is higher then 5. The present approach is satisfactory for description of solid-liquid phase transition of the Lennard-Jones model.
Thermodynamic Perturbation Theory for Solid-Liquid Phase Transition of Lennard-Jones Model
ZHOU Shi-Qi; ZHANG Xiao-Qi
2004-01-01
Both a free volume approach for Helmholtz free energy and a theoretically-based fitted formula for radial distribution function (rdf) of hard sphere solid are employed to describe the Helmholtz free energy of Lennard-Jones solid in the framework of the first order thermodynamic perturbation theory, which also is employed for the uniform LennardJones fluid. The dividing of the Lennard-Jones potential follows from the WCA prescription, but the specification of the equivalent hard sphere diameter is determined by a simple iteration procedure devised originally for liquid state, but extended to solid state in the present study. Two hundred sheiks are used in the rdf to get an accurate perturbation term.The present approach is very accurate for the description of excess Helmholtz free energy of LJ solid, but shows some deviation from the simulation for excess Helmholtz free energy of uniform LJ fluid when the reduced temperature kT/ε is higher then 5. The present approach is satisfactory for description of solid-liquid phase transition of the Lennard-Jones model.
Solid state drug-polymer miscibility studies using the model drug ABT-102.
Jog, Rajan; Gokhale, Rajeev; Burgess, Diane J
2016-07-25
Amorphous solid dispersions typically suffer storage stability issues due to: their amorphous nature, high drug loading, uneven drug:stabilizer ratio and plasticization effects as a result of hygroscopic excipients. An extensive solid state miscibility study was conducted to aid in understanding the mechanisms involved in drug/stabilizer interactions. ABT-102 (model drug) and nine different polymers with different molecular weights and viscosities were selected to investigate drug/polymer miscibility. Three different polymer:drug ratios (1:3, 1:1 and 3:1, w/w) were analyzed using: DSC, FTIR and PXRD. Three different techniques were used to prepare the amorphous solid dispersions: serial dilution, solvent evaporation and spray drying. Spray drying was the best method to obtain amorphous solid dispersions. However, under certain conditions amorphous formulations could be obtained using solvent evaporation. Melting point depression was used to calculate interaction parameters and free energy of mixing for the various drug polymer mixtures. The spray dried solid dispersions yielded a negative free energy of mixing which indicated strong drug-polymer miscibility compared to the solvent evaporation and serial dilution method. Soluplus was the best stabilizer compared to PVP and HPMC, which is probably a consequence of strong hydrogen bonding between the two CO moieties of soluplus and the drug NH moieities. Copyright © 2016. Published by Elsevier B.V.
National Aeronautics and Space Administration — The proposed research program aims at developing a variable-fidelity software tool set for aeroservothermoelastic-propulsive (ASTE-P) modeling that can be routinely...
National Aeronautics and Space Administration — The proposed research program aims at developing a variable-fidelity software tool set for aeroservothermoelastic-propulsive (ASTE-P) modeling that can be routinely...
Solid Lubrication Fundamentals and Applications
Miyoshi, Kazuhisa
2001-01-01
Solid Lubrication Fundamentals and Applications description of the adhesion, friction, abrasion, and wear behavior of solid film lubricants and related tribological materials, including diamond and diamond-like solid films. The book details the properties of solid surfaces, clean surfaces, and contaminated surfaces as well as discussing the structures and mechanical properties of natural and synthetic diamonds; chemical-vapor-deposited diamond film; surface design and engineering toward wear-resistant, self-lubricating diamond films and coatings. The author provides selection and design criteria as well as applications for synthetic and natural coatings in the commercial, industrial and aerospace industries..
Mathematical model of organic substrate degradation in solid waste windrow composting.
Seng, Bunrith; Kristanti, Risky Ayu; Hadibarata, Tony; Hirayama, Kimiaki; Katayama-Hirayama, Keiko; Kaneko, Hidehiro
2016-01-01
Organic solid waste composting is a complex process that involves many coupled physical, chemical and biological mechanisms. To understand this complexity and to ease in planning, design and management of the composting plant, mathematical model for simulation is usually applied. The aim of this paper is to develop a mathematical model of organic substrate degradation and its performance evaluation in solid waste windrow composting system. The present model is a biomass-dependent model, considering biological growth processes under the limitation of moisture, oxygen and substrate contents, and temperature. The main output of this model is substrate content which was divided into two categories: slowly and rapidly degradable substrates. To validate the model, it was applied to a laboratory scale windrow composting of a mixture of wood chips and dog food. The wastes were filled into a cylindrical reactor of 6 cm diameter and 1 m height. The simulation program was run for 3 weeks with 1 s stepwise. The simulated results were in reasonably good agreement with the experimental results. The MC and temperature of model simulation were found to be matched with those of experiment, but limited for rapidly degradable substrates. Under anaerobic zone, the degradation of rapidly degradable substrate needs to be incorporated into the model to achieve full simulation of a long period static pile composting. This model is a useful tool to estimate the changes of substrate content during composting period, and acts as a basic model for further development of a sophisticated model.
A Variational Model for Two-Phase Immiscible Electroosmotic Flow at Solid Surfaces
Shao, Sihong
2012-01-01
We develop a continuum hydrodynamic model for two-phase immiscible flows that involve electroosmotic effect in an electrolyte and moving contact line at solid surfaces. The model is derived through a variational approach based on the Onsager principle of minimum energy dissipation. This approach was first presented in the derivation of a continuum hydrodynamic model for moving contact line in neutral two-phase immiscible flows (Qian, Wang, and Sheng, J. Fluid Mech. 564, 333-360 (2006)). Physically, the electroosmotic effect can be formulated by the Onsager principle as well in the linear response regime. Therefore, the same variational approach is applied here to the derivation of the continuum hydrodynamic model for charged two-phase immiscible flows where one fluid component is an electrolyte exhibiting electroosmotic effect on a charged surface. A phase field is employed to model the diffuse interface between two immiscible fluid components, one being the electrolyte and the other a nonconductive fluid, both allowed to slip at solid surfaces. Our model consists of the incompressible Navier-Stokes equation for momentum transport, the Nernst-Planck equation for ion transport, the Cahn-Hilliard phase-field equation for interface motion, and the Poisson equation for electric potential, along with all the necessary boundary conditions. In particular, all the dynamic boundary conditions at solid surfaces, including the generalized Navier boundary condition for slip, are derived together with the equations of motion in the bulk region. Numerical examples in two-dimensional space, which involve overlapped electric double layer fields, have been presented to demonstrate the validity and applicability of the model, and a few salient features of the two-phase immiscible electroosmotic flows at solid surface. The wall slip in the vicinity of moving contact line and the Smoluchowski slip in the electric double layer are both investigated. © 2012 Global-Science Press.
Engineering bed models for solid fuel conversion process in grate-fired boilers
Costa, M.; Massarotti, N.; Indrizzi, V.
2014-01-01
A comparison between two numerical models describing the thermo-chemical conversion process of a solid fuel bed in a grate-fired boiler is presented. Both models consider the incoming biomass as subjected to drying, pyrolysis, gasification and combustion. In the first approach the biomass bed...... of the syngas predicted by the two models is equal to about 7%. The application to different types of biomass shows that the difference in the predictions increases as the carbon content grows. The phenomenological model, in fact, generally considers higher conversion rates of this element to volatiles...
Modelling Feature Design Based on Solid Works%基于Solid works建模特征设计
李彩霞; 范国勇
2008-01-01
研究了Solid Works零件建模特征的设计方法.针对Solid Works的特点提出草图绘制和特征绘制的几种不同的设计意图,分析了建模特征设计三种方法--层叠蛋糕法、制陶转盘法、制造法的优缺点.
A temperature-dependent surface free energy model for solid single crystals
Cheng, Tianbao; Fang, Daining; Yang, Yazheng
2017-01-01
A temperature-dependent theoretical model for the surface free energy of the solid single crystals is established. This model relates the surface free energy at the elevated temperatures to that at the reference temperature, the temperature-dependent specific heat at constant pressure and coefficient of the linear thermal expansion, the heat of phase transition, the melting heat, and the vapor heat. As examples, the surface free energies of Fe, Cu, Al, Ni, and Pb from 0 K to melting points are calculated and are in reasonable agreement with these from Tyson's theories and the experimental results. This model has obvious advantages compared to Tyson's semi-empirical equations from the aspect of physical meaning, applicable condition, and accuracy. The study shows that the surface free energy of the solid single crystals firstly remains approximately constant and then decreases linearly as temperature increases from 0 K to melting point.
Sabio, E.; Zamora, F.; González-García, C. M.; Ledesma, B.; Álvarez-Murillo, A.; Román, S.
2016-12-01
In this work, the adsorption kinetics of p-nitrophenol (PNP) onto several commercial activated carbons (ACs) with different textural and geometrical characteristics was studied. For this aim, a homogeneous diffusion solid model (HDSM) was used, which does take the adsorbent shape into account. The HDSM was solved by means of the finite element method (FEM) using the commercial software COMSOL. The different kinetic patterns observed in the experiments carried out can be described by the developed model, which shows that the sharp drop of adsorption rate observed in some samples is caused by the formation of a concentration wave. The model allows one to visualize the changes in concentration taking place in both liquid and solid phases, which enables us to link the kinetic behaviour with the main features of the carbon samples.
Modeling of Isobutane/Butene Alkylation Using Solid Acid Catalysts in a Fixed Bed Reactor
Liu Zheng; Tang Xiaojin; Hu Lifeng; Hou Shuandi
2016-01-01
A dynamic mass transfer model of isobutane/butene alkylation over solid acid catalysts in a ifxed bed reactor was established. In the model, a modiifed equation for the relationship between point activity and effective diffusion coefifcient was proposed. It is found that the simulation results ift the experimental data well and the breakthrough time of the bed layer is predicted accurately. By modeling the alkylation process, the time-space distribution of butene and point activity proifles of catalysts can be obtained. Furthermore, the reasons for the deactivation of solid acid catalysts were investigated. It indicates that the main reason for the deactivation of catalysts is the site coverage near the inlet of the reactor, while it is ascribed to the steric effect in the region far away from the inlet.
AN EXPERT APPROACH ON AUTOMATIC SOLID MODEL RECONSTRUCTION FROM 2D PROJECTIONS
İsmail ŞAHİN
2008-02-01
Full Text Available This paper examines how to automatically reconstruct three dimentions (3D models from their orthographic two and three views and explains a new approach developed for that purpose. The approach is based on the identification of geometric features with the interpretation of 2B views, their volumetric intersections and reconstruction of solid models. A number of rules have been defined for this goal and they implemented on a prototype software with the approach of expert systems. The developed software allows determination of some features efficiently such as slot, holes, blind holes, closed prismatic holes, etc. Another contrubition of this research is to reconstruct solid models from their full section and half section views that is almost noneexistend in the releated literature.
A mathematical model for municipal solid waste management - A case study in Hong Kong.
Lee, C K M; Yeung, C L; Xiong, Z R; Chung, S H
2016-12-01
With the booming economy and increasing population, the accumulation of waste has become an increasingly arduous issue and has aroused the attention from all sectors of society. Hong Kong which has a relative high daily per capita domestic waste generation rate in Asia has not yet established a comprehensive waste management system. This paper conducts a review of waste management approaches and models. Researchers highlight that mathematical models provide useful information for decision-makers to select appropriate choices and save cost. It is suggested to consider municipal solid waste management in a holistic view and improve the utilization of waste management infrastructures. A mathematical model which adopts integer linear programming and mixed integer programming has been developed for Hong Kong municipal solid waste management. A sensitivity analysis was carried out to simulate different scenarios which provide decision-makers important information for establishing Hong Kong waste management system.
Hua Li
2015-01-01
Full Text Available This study develops a sustainability assessment model for analysis and decision-making of the impact of China’s municipal solid waste management enhancement strategy options based on three waste treatment scenarios: landfill disposal, waste-to-energy incineration, and a combination of a material recovery facility and composting. The model employs life cycle assessment, health risk assessment, and full cost accounting to evaluate the treatment scenarios regarding safeguarding public health, protecting the environment and conserving resources, and economic feasibility. The model then uses an analytic hierarchy process for an overall appraisal of sustainability. Results suggest that a combination of material recovery and composting is the most efficient option. The study results clarify sustainable attributes, suitable predications, evaluation modeling, and stakeholder involvement issues in solid waste management. The demonstration of the use of sustainability assessment model (SAM provides flexibility by allowing assessment for a municipal solid waste management (MSWM strategy on a case-by-case basis, taking into account site-specific factors, therefore it has the potential for flexible applications in different communities/regions.
Robust and Adaptive Control With Aerospace Applications
Lavretsky, Eugene
2013-01-01
Robust and Adaptive Control shows the reader how to produce consistent and accurate controllers that operate in the presence of uncertainties and unforeseen events. Driven by aerospace applications the focus of the book is primarily on continuous-dynamical systems. The text is a three-part treatment, beginning with robust and optimal linear control methods and moving on to a self-contained presentation of the design and analysis of model reference adaptive control (MRAC) for nonlinear uncertain dynamical systems. Recent extensions and modifications to MRAC design are included, as are guidelines for combining robust optimal and MRAC controllers. Features of the text include: · case studies that demonstrate the benefits of robust and adaptive control for piloted, autonomous and experimental aerial platforms; · detailed background material for each chapter to motivate theoretical developments; · realistic examples and simulation data illustrating key features ...
A multi-objective model for sustainable recycling of municipal solid waste.
Mirdar Harijani, Ali; Mansour, Saeed; Karimi, Behrooz
2017-04-01
The efficient management of municipal solid waste is a major problem for large and populated cities. In many countries, the majority of municipal solid waste is landfilled or dumped owing to an inefficient waste management system. Therefore, an optimal and sustainable waste management strategy is needed. This study introduces a recycling and disposal network for sustainable utilisation of municipal solid waste. In order to optimise the network, we develop a multi-objective mixed integer linear programming model in which the economic, environmental and social dimensions of sustainability are concurrently balanced. The model is able to: select the best combination of waste treatment facilities; specify the type, location and capacity of waste treatment facilities; determine the allocation of waste to facilities; consider the transportation of waste and distribution of processed products; maximise the profit of the system; minimise the environmental footprint; maximise the social impacts of the system; and eventually generate an optimal and sustainable configuration for municipal solid waste management. The proposed methodology could be applied to any region around the world. Here, the city of Tehran, Iran, is presented as a real case study to show the applicability of the methodology.
Modelling Gas Adsorption in Porous Solids: Roles of Surface Chemistry and Pore Architecture
Satyanarayana Bonakala; Sundaram Balasubramanian
2015-10-01
Modelling the adsorption of small molecule gases such as N2 , CH4 and CO2 in porous solids can provide valuable insights for the development of next generation materials. Employing a grand canonical Monte Carlo simulation code developed in our group, the adsorption isotherms of CH4 and CO2 in many metal organic frameworks have been calculated and compared with experimental results. The isotherms computed within a force field approach are able to well reproduce the experimental data. Key functional groups in the solids which interact with gas molecules and the nature of their interactions have been identified. The most favorable interaction sites for CH4 and CO2 in the framework solids are located in the linkers which are directed towards the pores. The structure of a perfluorinated conjugated microporous polymer has been modelled and it is predicted to take up 10% more CO2 than its hydrogenated counterpart. In addition, the vibrational, orientational and diffusive properties of CO2 adsorbed in the solids have been examined using molecular dynamics simulations. Intermolecular modes of such adsorbed species exhibit a blue shift with increasing gas pressure.
Demerdash, N. A. O.; Nehl, T. W.
1979-01-01
A mathematical model was developed and computerized simulations were obtained for a brushless dc motor. Experimentally obtained oscillograms of the machine phase currents are presented and the corresponding current and voltage waveforms for various modes of operation of the motor are presented and discussed.
Pornprasertsuk, Rojana
Because of the steep increase in oil prices, the global warming effect and the drive for energy independence, alternative energy research has been encouraged worldwide. The sustainable fuels such as hydrogen, biofuel, natural gas, and solar energy have attracted the attention of researchers. To convert these fuels into a useful energy source, an energy conversion device is required. Fuel cells are one of the energy conversion devices which convert chemical potentials into electricity. Due to their high efficiency, the ease to scale from 1 W range to megawatts range, no recharging requirement and the lack of CO2 and NOx emission (if H2 and air/O 2 are used), fuel cells have become a potential candidate for both stationary power generators and portable applications. This thesis has been focused primarily on solid oxide fuel cell (SOFC) studies due to its high efficiency, varieties of fuel choices, and no water management problem. At the present, however, practical applications of SOFCs are limited by high operating temperatures that are needed to create the necessary oxide-ion vacancy mobility in the electrolyte and to create sufficient electrode reactivities. This thesis introduces several experimental and theoretical approaches to lower losses both in the electrolyte and the electrodes. Yttria stabilized zirconia (YSZ) is commonly used as a solid electrolyte for SOFCs due to its high oxygen-ion conductivity. To improve the ionic conductivity for low temperature applications, an approach that involves dilating the structure by irradiation and introducing edge dislocations into the electrolyte was studied. Secondly, to understand the activation loss in SOFC, the kinetic Monte Carlo (KMC) technique was implemented to model the SOFC operation to determining the rate-limiting step due to the electrodes on different sizes of Pt catalysts. The isotope exchange depth profiling technique was employed to investigate the irradiation effect on the ionic transport in different
Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes.
García-Gen, Santiago; Sousbie, Philippe; Rangaraj, Ganesh; Lema, Juan M; Rodríguez, Jorge; Steyer, Jean-Philippe; Torrijos, Michel
2015-01-01
A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 gVS/Ld. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes.
Modeling the impact of solid noise barriers on near road air quality
Venkatram, Akula; Isakov, Vlad; Deshmukh, Parikshit; Baldauf, Richard
2016-09-01
Studies based on field measurements, wind tunnel experiments, and controlled tracer gas releases indicate that solid, roadside noise barriers can lead to reductions in downwind near-road air pollutant concentrations. A tracer gas study showed that a solid barrier reduced pollutant concentrations as much as 80% next to the barrier relative to an open area under unstable meteorological conditions, which corresponds to typical daytime conditions when residents living or children going to school near roadways are most likely to be exposed to traffic emissions. The data from this tracer gas study and a wind tunnel simulation were used to develop a model to describe dispersion of traffic emissions near a highway in the presence of a solid noise barrier. The model is used to interpret real-world data collected during a field study conducted in a complex urban environment next to a large highway in Phoenix, Arizona, USA. We show that the analysis of the data with the model yields useful information on the emission factors and the mitigation impact of the barrier on near-road air quality. The estimated emission factors for the four species, ultrafine particles, CO, NO2, and black carbon, are consistent with data cited in the literature. The results suggest that the model accounted for reductions in pollutant concentrations from a 4.5 m high noise barrier, ranging from 40% next to the barrier to 10% at 300 m from the barrier.
Dynamic modeling of total suspended solids in the wetland Jaboque, Bogotá (Colombia
Julio Eduardo Beltrán-Vargas
2012-12-01
Full Text Available We propose a dynamic simulation model to provide a general explanation for the behavior of total suspended solids in the Jaboque wetland (Bogotá DC. The analyses were performed in three areas with distinct physical and chemical characteristics. The model predicted concentrations of total suspended solids in the months of April, May, June, October and November. Values ranged from 85 mg L-1 and 101 mg L-1 with an average of 65.12 mg L-1 with a hydraulic time retention between eight and nine days per year for the first area, the second area between 57 and 69 with an average of 50 mg L-1 with a hydraulic time between 20 and 23 days per year and in the third area between 56 mg L-1 and 67 mg L-1 with a mean of 48.8 mg L-1 and a hydraulic retention time between 24 and 26 days per year. The months of December, January, February, August and September showed a tendency to have lower values. The estimated values of total suspended solids based on our model had an acceptable correspondence, R2 = 0.95, 0.71, 0.67, with the actual values in all cases. The relative error for each area was 0.10, 0.20 and 0.26, demonstrating that the model does not overestimate the results.
AN Zhi-Wu; WANG Xiao-Min; LI Ming-Xuan; DENG Ming-Xi; MAO Jie
2009-01-01
Based on the exact solutions for the second-harmonic generations of the fundamental longitudinal and transverse waves propagating normally through a thin elastic layer between two solids, the approximate representations termed as 'nonlinear spring models' relating the stresses and displacements on both sides of the interface are rigorously developed by asymptotic expansions of the wave fields for an elastic layer in the limit of small thickness to wavelength ratio. The applicability for the so-called nonlinear spring models is numerically analyzed by comparison with exact solutions for the second harmonic wave reflections. The present nonlinear spring models lay a theoretical foundation to evaluate the interracial properties by nonlinear acoustic waves.
A hybrid cellular automaton model of solid tumor growth and bioreductive drug transport.
Kazmi, Nabila; Hossain, M A; Phillips, Roger M
2012-01-01
Bioreductive drugs are a class of hypoxia selective drugs that are designed to eradicate the hypoxic fraction of solid tumors. Their activity depends upon a number of biological and pharmacological factors and we used a mathematical modeling approach to explore the dynamics of tumor growth, infusion, and penetration of the bioreductive drug Tirapazamine (TPZ). An in-silico model is implemented to calculate the tumor mass considering oxygen and glucose as key microenvironmental parameters. The next stage of the model integrated extra cellular matrix (ECM), cell-cell adhesion, and cell movement parameters as growth constraints. The tumor microenvironments strongly influenced tumor morphology and growth rates. Once the growth model was established, a hybrid model was developed to study drug dynamics inside the hypoxic regions of tumors. The model used 10, 50 and 100 \\mu {\\rm M} as TPZ initial concentrations and determined TPZ pharmacokinetic (PK) (transport) and pharmacodynamics (cytotoxicity) properties inside hypoxic regions of solid tumor. The model results showed that diminished drug transport is a reason for TPZ failure and recommend the optimization of the drug transport properties in the emerging TPZ generations. The modeling approach used in this study is novel and can be a step to explore the behavioral dynamics of TPZ.
Next generation experiments and models for shock initiation and detonation of solid explosives
Tarver, C M
1999-06-01
Current phenomenological hydrodynamic reactive flow models, such as Ignition and Growth and Johnson- Tang-Forest, when normalized to embedded gauge and laser velocimetry data, have been very successful in predicting shock initiation and detonation properties of solid explosives in most scenarios. However, since these models use reaction rates based on the compression and pressure of the reacting mixture, they can not easily model situations in which the local temperature, which controls the local reaction rate, changes differently from the local pressure. With the advent of larger, faster, parallel computers, microscopic modeling of the hot spot formation processes and Arrhenius chemical kinetic reaction rates that dominate shock initiation and detonation can now be attempted. Such a modeling effort can not be successful without nanosecond or better time resolved experimental data on these processes. The experimental and modeling approaches required to build the next generation of physically realistic reactive flow models are discussed.
Paumel, K.; Moysan, J.; Chatain, D.; Corneloup, G.; Baqué, F.
2011-08-01
Ultrasonic inspection of sodium-cooled fast reactor requires a good acoustic coupling between the transducer and the liquid sodium. Ultrasonic transmission through a solid surface in contact with liquid sodium can be complex due to the presence of microscopic gas pockets entrapped by the surface roughness. Experiments are run using substrates with controlled roughness consisting of a network of holes and a modeling approach is then developed. In this model, a gas pocket stiffness at a partially solid-liquid interface is defined. This stiffness is then used to calculate the transmission coefficient of ultrasound at the entire interface. The gas pocket stiffness has a static, as well as an inertial component, which depends on the ultrasonic frequency and the radiative mass.
Solid Modeling and Finite Element Analysis of an Overhead Crane Bridge
C. Alkin
2005-01-01
Full Text Available The design of an overhead crane bridge with a double box girder has been investigated and a case study of a crane with 35 ton capacity and 13 m span length has been conducted. In the initial phase of the case study, conventional design calculations proposed by F. E. M. Rules and DIN standards were performed to verify the stress and deflection levels. The crane design was modeled using both solids and surfaces. Finite element meshes with 4-node tetrahedral and 4-node quadrilateral shell elements were generated from the solid and shell models, respectively. After a comparison of the finite element analyses, the conventional calculations and performance of the existing crane, the analysis with quadratic shell elements was found to give the most realistic results. As a result of this study, a design optimization method for an overhead crane is proposed.
Dongping TAO
2011-01-01
The molecular interaction vacancy model (MIVM) is used to estimate simultaneously activities of all components in a range of entire composition of six binary oxide solid solutions and the MnO-FeO-CaO ternary solid solution by their binary infinite dilute activity coefficients.The average errors are the 0.03%-5.0% for the binaries and the 4.11%-25.2% for the ternary which is less than that (4.84%-41.2%) of the sub-regular solution model (SRSM).This shows that MIVM is more effective and reliable than SRSM for the ternary and does not depend on a polynomial approximation with some ternary adjustable parameters.
Modelling interstellar physics and chemistry: implications for surface and solid-state processes.
Williams, David; Viti, Serena
2013-07-13
We discuss several types of regions in the interstellar medium of the Milky Way and other galaxies in which the chemistry appears to be influenced or dominated by surface and solid-state processes occurring on or in interstellar dust grains. For some of these processes, for example, the formation of H₂ molecules, detailed experimental and theoretical approaches have provided excellent fundamental data for incorporation into astrochemical models. In other cases, there is an astrochemical requirement for much more laboratory and computational study, and we highlight these needs in our description. Nevertheless, in spite of the limitations of the data, it is possible to infer from astrochemical modelling that surface and solid-state processes play a crucial role in astronomical chemistry from early epochs of the Universe up to the present day.
Kauranen, P. S.
1993-04-01
In the solid state concept of a direct methanol fuel cell (DMFC), methanol is directly oxidized at the anode of a solid polymer electrolyte fuel cell (SPEFC). Mathematical modelling of the transport and reaction phenomena within the electrodes and the electrolyte membrane is needed in order to get a closer insight into the operation of the fuel cell. In the work, macro-homogenous porous electrode and dilute solution theories are used to derive the phenomenological equations describing the transport and reaction mechanisms in a SPEFC single cell. The equations are first derived for a conventional H2/air SPEFC, and then extended for a DMFC. The basic model is derived in a one dimensional form in which it is assumed that species transport take place only in the direction crossing the cell sandwich. In addition, two dimensional descriptions of the catalyst layer are reviewed.
Computer-aided design model for anaerobic-phased-solids digester system
Zhang, Z.; Zhang, R. [University of California, Davis, CA (United States); Tiangco, V. [California Energy Commission, Sacramento, CA (United States)
1999-07-01
The anaerobic-phased-solids (APS) digester system is a newly developed anaerobic digestion system for converting solid wastes, such as crop residues and food wastes, into biogas for power and heat generation. A computer-aided engineering design model has been developed to design the APS-digester system and study the heat transfer from the reactors and energy production of the system. Simulation results of a case study are presented by using the model to predict the heating energy requirement and biogas energy production for anaerobic digestion of garlic waste. The important factors, such as environmental conditions, insulation properties, and characteristics of the wastes, on net energy production are also investigated. (author)
Janvier, C.
1998-04-02
The oxides-gaseous dioxygen equilibria and the textural thermal stability of six zirconium-cerin solutions Ce{sub 1-x}Zr{sub x}O{sub 2} (0
Revisiting low-fidelity two-fluid models for gas-solids transport
Adeleke, Najeem; Adewumi, Michael; Ityokumbul, Thaddeus
2016-08-01
Two-phase gas-solids transport models are widely utilized for process design and automation in a broad range of industrial applications. Some of these applications include proppant transport in gaseous fracking fluids, air/gas drilling hydraulics, coal-gasification reactors and food processing units. Systems automation and real time process optimization stand to benefit a great deal from availability of efficient and accurate theoretical models for operations data processing. However, modeling two-phase pneumatic transport systems accurately requires a comprehensive understanding of gas-solids flow behavior. In this study we discuss the prevailing flow conditions and present a low-fidelity two-fluid model equation for particulate transport. The model equations are formulated in a manner that ensures the physical flux term remains conservative despite the inclusion of solids normal stress through the empirical formula for modulus of elasticity. A new set of Roe-Pike averages are presented for the resulting strictly hyperbolic flux term in the system of equations, which was used to develop a Roe-type approximate Riemann solver. The resulting scheme is stable regardless of the choice of flux-limiter. The model is evaluated by the prediction of experimental results from both pneumatic riser and air-drilling hydraulics systems. We demonstrate the effect and impact of numerical formulation and choice of numerical scheme on model predictions. We illustrate the capability of a low-fidelity one-dimensional two-fluid model in predicting relevant flow parameters in two-phase particulate systems accurately even under flow regimes involving counter-current flow.
Brahmi, Mounaouer; Belhadi, Noureddine Hamed; Hamdi, Helmi; Hassen, Abdennaceur
2010-01-01
This work aimed to study UV-resistant strains of Pseudomonas aeruginosa, to propose a formulation of the kinetics of secondary treated wastewater disinfection and to underline the influence of suspended solids on the inactivation kinetics of these strains. Some investigations were carried out for the validation of some simulation models, from the simplest, the kinetics model of Chick-Watson reduced to first order, to rather complex models such as multi-kinetic and Collins-Selleck models. Results revealed that the involved processes of UV irradiation were too complex to be approached by a simplified formulation, even in the case of specific strains of microorganisms and the use of nearly constant UV radiation intensity. In fact, the application of Chick-Watson model in its original form is not representative of the kinetics of UV disinfection. Modification, taking into account the speed change during the disinfection process, has not significantly improved results. On the other hand, the application of Collins-Selleck model demonstrates that it was necessary to exceed a least dose of critical radiation to start the process of inactivation. To better explain the process of inactivation, we have assumed that the action of disinfectant on the survival of lonely microorganisms is faster than its action on suspended solids protected or agglomerated to each others. We can assume in this case the existence of two inactivation kinetics during the processes (parallel and independent) of the first-order. For this reason, the application of a new kinetic model by introducing a third factor reflecting the influence of suspended solids in water on disinfection kinetics appeared to be determinant for modeling UV inactivation of P. aeruginosa in secondary treated wastewater.
Revisiting low-fidelity two-fluid models for gas–solids transport
Adeleke, Najeem, E-mail: najm@psu.edu; Adewumi, Michael, E-mail: m2a@psu.edu; Ityokumbul, Thaddeus
2016-08-15
Two-phase gas–solids transport models are widely utilized for process design and automation in a broad range of industrial applications. Some of these applications include proppant transport in gaseous fracking fluids, air/gas drilling hydraulics, coal-gasification reactors and food processing units. Systems automation and real time process optimization stand to benefit a great deal from availability of efficient and accurate theoretical models for operations data processing. However, modeling two-phase pneumatic transport systems accurately requires a comprehensive understanding of gas–solids flow behavior. In this study we discuss the prevailing flow conditions and present a low-fidelity two-fluid model equation for particulate transport. The model equations are formulated in a manner that ensures the physical flux term remains conservative despite the inclusion of solids normal stress through the empirical formula for modulus of elasticity. A new set of Roe–Pike averages are presented for the resulting strictly hyperbolic flux term in the system of equations, which was used to develop a Roe-type approximate Riemann solver. The resulting scheme is stable regardless of the choice of flux-limiter. The model is evaluated by the prediction of experimental results from both pneumatic riser and air-drilling hydraulics systems. We demonstrate the effect and impact of numerical formulation and choice of numerical scheme on model predictions. We illustrate the capability of a low-fidelity one-dimensional two-fluid model in predicting relevant flow parameters in two-phase particulate systems accurately even under flow regimes involving counter-current flow.
Assessment of municipal solid waste settlement models based on field-scale data analysis.
Bareither, Christopher A; Kwak, Seungbok
2015-08-01
An evaluation of municipal solid waste (MSW) settlement model performance and applicability was conducted based on analysis of two field-scale datasets: (1) Yolo and (2) Deer Track Bioreactor Experiment (DTBE). Twelve MSW settlement models were considered that included a range of compression behavior (i.e., immediate compression, mechanical creep, and biocompression) and range of total (2-22) and optimized (2-7) model parameters. A multi-layer immediate settlement analysis developed for Yolo provides a framework to estimate initial waste thickness and waste thickness at the end-of-immediate compression. Model application to the Yolo test cells (conventional and bioreactor landfills) via least squares optimization yielded high coefficient of determinations for all settlement models (R(2)>0.83). However, empirical models (i.e., power creep, logarithmic, and hyperbolic models) are not recommended for use in MSW settlement modeling due to potential non-representative long-term MSW behavior, limited physical significance of model parameters, and required settlement data for model parameterization. Settlement models that combine mechanical creep and biocompression into a single mathematical function constrain time-dependent settlement to a single process with finite magnitude, which limits model applicability. Overall, all models evaluated that couple multiple compression processes (immediate, creep, and biocompression) provided accurate representations of both Yolo and DTBE datasets. A model presented in Gourc et al. (2010) included the lowest number of total and optimized model parameters and yielded high statistical performance for all model applications (R(2)⩾0.97).
Verotti Filho, C.; Costa, Glória Meyberg Nunes
1996-01-01
p. 351–355 Solubilities of several organic solids in four supercritical fluids are calculated with Soave and Peng-Robinson equations of state, incorporating excess Gibbs free energy into the mixing rules, with Heidemann-Kokal, Wong-Sandler and MHV2 procedures. Three excess Gibbs free energy models are used in the mixing rules: NRTL, UNiQUAC and UNIFAC. Furthermore, a comparison between these mixing rules and conventional two-binary-parameter form and modification of the excluded volume par...
Modeling barriers of solid waste to energy practices: An Indian perspective
S. Bag
2016-01-01
Full Text Available In recent years managing solid wastes has been one of the burning problems in front of state and local municipal authorities. This is mainly due to scarcity of lands for landfill sites. In this context experts suggest that conversion of solid waste to energy and useful component is the best approach to reduce space and public health related problems. The entire process has to be managed by technologies that prevent pollution and protect the environment and at the same time minimize the cost through recovery of energy. Energy recovery in the form of electricity, heat and fuel from the waste using different technologies is possible through a variety of processes, including incineration, gasification, pyrolysis and anaerobic digestion. These processes are often grouped under “Waste to Energy technologies”. The objective of the study is twofold. First authors assessed the current status of solid waste management practices in India. Secondly the leading barriers are identified and Interpretive structural modeling technique and MICMAC analysis is performed to identify the contextual interrelationships between leading barriers influencing the solid waste to energy programs in the country. Finally the conclusions are drawn which will assist policy makers in designing sustainable waste management programs.
Fdez-Güelfo, L A; Álvarez-Gallego, C; Sales Márquez, D; Romero García, L I
2011-01-01
Solid retention time (SRT) is a very important operational variable in continuous and semicontinuous waste treatment processes since the organic matter removal efficiency--expressed in terms of percentage of Dissolved Organic Carbon (% DOC) or Volatile Solids (% VS) removed--and the biogas or methane production are closely related with the SRT imposed. Optimum SRT is depending on the waste characteristics and the microorganisms involved in the process and, hence, it should be determined specifically in each case. In this work a series of experiments were carried out to determine the effect of SRT, from 40 to 8 days, on the performance of the dry (30% Total Solids) thermophilic (55°C) anaerobic digestion of organic fraction of Municipal Solid Wastes (OFMSW) operating at semicontinuous regime of feeding. The experimental results show than 15days is the optimum SRT (the best between all proved) for this process. Besides, data of organic matter concentration and methane production versus SRT have been used to obtain the kinetic parameters of the kinetic model of Romero García (1991): the maximum specific growth rate of the microorganisms (μmax=0.580 days(-1)) and the fraction of substrate non-biodegradable (α=0.268).
Aerospace concurrent engineering: a modern global approach
Imbert, Mariano; Li, Xiaoxing
2009-12-01
System engineering aspects, like concurrent engineering (CE) in the aerospace sector, has been studied by many authors. The change and evolution in this regard is continually influenced by the information technology advances. But global cooperation is only discussed by developed countries and high technology corporations. A review of CE and its ramifications in the aerospace industry is presented. Based on the current literature, the general lifecycle of a spacecraft and its phases are explained as well as the tools that are implemented in today's industry. In this paper we propose a new approach for the product development process in the spacecraft production industry the Aerospace Concurrent Engineering (ACE), which is mainly focused in the technology itself, its optimal design and environment impact rather than costs and marketing impact. And the potential of globally oriented research and implementation of space programs is discussed for its consideration.
Machine intelligence and autonomy for aerospace systems
Heer, Ewald (Editor); Lum, Henry (Editor)
1988-01-01
The present volume discusses progress toward intelligent robot systems in aerospace applications, NASA Space Program automation and robotics efforts, the supervisory control of telerobotics in space, machine intelligence and crew/vehicle interfaces, expert-system terms and building tools, and knowledge-acquisition for autonomous systems. Also discussed are methods for validation of knowledge-based systems, a design methodology for knowledge-based management systems, knowledge-based simulation for aerospace systems, knowledge-based diagnosis, planning and scheduling methods in AI, the treatment of uncertainty in AI, vision-sensing techniques in aerospace applications, image-understanding techniques, tactile sensing for robots, distributed sensor integration, and the control of articulated and deformable space structures.
Wireless Sensing Opportunities for Aerospace Applications
William Wilson
2008-07-01
Full Text Available Wireless sensors and sensor networks is an emerging technology area with many applications within the aerospace industry. Integrated vehicle health monitoring (IVHM of aerospace vehicles is needed to ensure the safety of the crew and the vehicle, yet often high costs, weight, size and other constraints prevent the incorporation of instrumentation onto spacecraft. This paper presents a few of the areas such as IVHM, where new wireless sensing technology is needed on both existing vehicles as well as future spacecraft. From ground tests to inflatable structures to the International Space Station, many applications could receive benefits from small, low power, wireless sensors. This paper also highlights some of the challenges that need to overcome when implementing wireless sensor networks for aerospace vehicles.
Sealed aerospace metal-hydride batteries
Coates, Dwaine
1992-01-01
Nickel metal hydride and silver metal hydride batteries are being developed for aerospace applications. There is a growing market for smaller, lower cost satellites which require higher energy density power sources than aerospace nickel-cadmium at a lower cost than space nickel-hydrogen. These include small LEO satellites, tactical military satellites and satellite constellation programs such as Iridium and Brilliant Pebbles. Small satellites typically do not have the spacecraft volume or the budget required for nickel-hydrogen batteries. NiCd's do not have adequate energy density as well as other problems such as overcharge capability and memory effort. Metal hydride batteries provide the ideal solution for these applications. Metal hydride batteries offer a number of advantages over other aerospace battery systems.
Aerospace manpower transfer to small business enterprises
Green, M. K.
1972-01-01
The feasibility of a program to effect transfer of aerospace professional people from the ranks of the unemployed into gainful employment in the small business community was investigated. The effectiveness of accomplishing transfer of technology from the aerospace effort into the private sector through migration of people rather than products or hardware alone was also studied. Two basic methodologies were developed. One involves the matching of ex-aerospace professionals and small companies according to their mutual needs. A training and indoctrination program is aimed at familiarizing the professional with the small company environment, and a program of follow-up counseling is defined. The second methodology incorporates efforts to inform and arouse interest among the nonaerospace business community toward affirmative action programs that will serve mutual self-interests of the individuals, companies, and communities involved.
Ray, Nadja; Rupp, Andreas; Prechtel, Alexander
2017-09-01
Upscaling transport in porous media including both biomass development and simultaneous structural changes in the solid matrix is extremely challenging. This is because both affect the medium's porosity as well as mass transport parameters and flow paths. We address this challenge by means of a multiscale model. At the pore scale, the local discontinuous Galerkin (LDG) method is used to solve differential equations describing particularly the bacteria's and the nutrient's development. Likewise, a sticky agent tightening together solid or bio cells is considered. This is combined with a cellular automaton method (CAM) capturing structural changes of the underlying computational domain stemming from biomass development and solid restructuring. Findings from standard homogenization theory are applied to determine the medium's characteristic time- and space-dependent properties. Investigating these results enhances our understanding of the strong interplay between a medium's functional properties and its geometric structure. Finally, integrating such properties as model parameters into models defined on a larger scale enables reflecting the impact of pore scale processes on the larger scale.
Surface clogging process modeling of suspended solids during urban stormwater aquifer recharge
Zijia Wang; Xinqiang Du; Yuesuo Yang; Xueyan Ye
2012-01-01
Aquifer recharge,which uses urban stormwater,is an effective technique to control the negative effects of groundwater overexploitation,while clogging problems in infiltration systems remain the key restricting factor in broadening its practice.Quantitative understanding of the clogging process is still very poor.A laboratory study was conducted to understand surface physical clogging processes,with the primary aim of developing a model for predicting suspended solid clogging processes before aquifer recharge projects start.The experiments investigated the clogging characteristics of different suspended solid sizes in recharge water by using a series of one-dimensional fine quartz sand columns.The results showed that the smaller the suspended particles in recharge water,the farther the distance of movement and the larger the scope of clogging in porous media.Clogging extents in fine sand were 1 cm,for suspended particle size ranging from 0.075 to 0.0385 mm,and 2 cm,for particles less than 0.0385 mm.In addition,clogging development occurred more rapidly for smaller suspended solid particles.It took 48,42,and 36 hr respectively,for large-,medium-,and small-sized particles to reach pre-determined clogging standards.An empirical formula and iteration model for the surface clogging evolution process were derived.The verification results obtained from stormwater recharge into fine sand demonstrated that the model could reflect the real laws of the surface clogging process.
Modeling Physical Stability of Amorphous Solids Based on Temperature and Moisture Stresses.
Zhu, Donghua Alan; Zografi, George; Gao, Ping; Gong, Yuchuan; Zhang, Geoff G Z
2016-09-01
Isothermal microcalorimetry was utilized to monitor the crystallization process of amorphous ritonavir (RTV) and its hydroxypropylmethylcellulose acetate succinate-based amorphous solid dispersion under various stressed conditions. An empirical model was developed: ln(τ)=ln(A)+EaRT-b⋅wc, where τ is the crystallization induction period, A is a pre-exponential factor, Ea is the apparent activation energy, b is the moisture sensitivity parameter, and wc is water content. To minimize the propagation of errors associated with the estimates, a nonlinear approach was used to calculate mean estimates and confidence intervals. The physical stability of neat amorphous RTV and RTV in hydroxypropylmethylcellulose acetate succinate solid dispersions was found to be mainly governed by the nucleation kinetic process. The impact of polymers and moisture on the crystallization process can be quantitatively described by Ea and b in this Arrhenius-type model. The good agreement between the measured values under some less stressful test conditions and those predicted, reflected by the slope and R(2) of the correlation plot of these 2 sets of data on a natural logarithm scale, indicates its predictability of long-term physical stability of amorphous RTV in solid dispersions. To further improve the model, more understanding of the impact of temperature and moisture on the amorphous physical stability and fundamentals regarding nucleation and crystallization is needed.
Numerical evaluation of turbulence models for dense to dilute gas-solid flows in vertical conveyor
Salar Azizi; Dariush Mowla; Goodarz Ahmadi
2012-01-01
A two-fluid model (TFM) of multiphase flows based on the kinetic theory and small frictional limit boundary condition of granular flow was used to study the behavior of dense to dilute gas-solid flows in vertical pneumatic conveyor.An axisymmetric 2-dimensional,vertical pipe with 5.6 m length and 0.01 m internal diameter was chosen as the computation domain,same to that used for experimentation in the literature.The chosen particles are spherical,of diameter 1.91 mm and density 2500 kg/m3.Turbulence interaction between the gas and particle phases was investigated by Simonin's and Ahmadi's models and their numerical results were validated for dilute to dense conveying of particles.Flow regimes transition and pressure drop were predicted.Voidage and velocity profiles of each phase were calculated in radial direction at different lengths of the conveying pipe.It was found that the voidage has a minimum,and gas and solid velocities have maximum values along the center line of the conveying pipe and pressure drop has a minimum value in transition from dense slugging to dilute stable flow regime.Slug length and pressure fluctuation reduction were predicted with increasing gas velocity,too.It is shown that solid phase turbulence plays a significant role in numerical prediction of hydrodynamics of conveyor and the capability of particles turbulence models depends on tuning parameters of slip-wall boundary condition.
Yan-jie Ni
2016-04-01
Full Text Available A 30 mm electrothermal-chemical (ETC gun experimental system is employed to research the burning rate characteristics of 4/7 high-nitrogen solid propellant. Enhanced gas generation rates (EGGR of propellants during and after electrical discharges are verified in the experiments. A modified 0D internal ballistic model is established to simulate the ETC launch. According to the measured pressure and electrical parameters, a transient burning rate law including the influence of EGGR coefficient by electric power and pressure gradient (dp/dt is added into the model. The EGGR coefficient of 4/7 high-nitrogen solid propellant is equal to 0.005 MW−1. Both simulated breech pressure and projectile muzzle velocity accord with the experimental results well. Compared with Woodley's modified burning rate law, the breech pressure curves acquired by the transient burning rate law are more consistent with test results. Based on the parameters calculated in the model, the relationship among propellant burning rate, pressure gradient (dp/dt and electric power is analyzed. Depending on the transient burning rate law and experimental data, the burning of solid propellant under the condition of plasma is described more accurately.
Yan-jie NI; Yong JIN; Gang WAN; Chun-xia YANG; Hai-yuan LI; Bao-ming LI
2016-01-01
A 30 mm electrothermal-chemical (ETC) gun experimental system is employed to research the burning rate characteristics of 4/7 high-nitrogen solid propellant. Enhanced gas generation rates (EGGR) of propellants during and after electrical discharges are verified in the experiments. A modified 0D internal ballistic model is established to simulate the ETC launch. According to the measured pressure and electrical parameters, a transient burning rate law including the influence of EGGR coefficient by electric power and pressure gradient (dp/dt) is added into the model. The EGGR coefficient of 4/7 high-nitrogen solid propellant is equal to 0.005 MW−1. Both simulated breech pressure and projectile muzzle velocity accord with the experimental results well. Compared with Woodley’s modified burning rate law, the breech pressure curves acquired by the transient burning rate law are more consistent with test results. Based on the parameters calculated in the model, the relationship among propellant burning rate, pressure gradient (dp/dt) and electric power is analyzed. Depending on the transient burning rate law and experimental data, the burning of solid propellant under the condition of plasma is described more accurately.
J. P. M. Whitty
2014-01-01
Full Text Available A novel computational technique is presented for embedding mass-loss due to burning into the ANSYS finite element modelling code. The approaches employ a range of computational modelling methods in order to provide more complete theoretical treatment of thermoelasticity absent from the literature for over six decades. Techniques are employed to evaluate structural integrity (namely, elastic moduli, Poisson’s ratios, and compressive brittle strength of honeycomb systems known to approximate three-dimensional cellular chars. That is, reducing the mass of diagonal ribs and both diagonal-plus-vertical ribs simultaneously show rapid decreases in the structural integrity of both conventional and reentrant (auxetic, i.e., possessing a negative Poisson’s ratio honeycombs. On the other hand, reducing only the vertical ribs shows initially modest reductions in such properties, followed by catastrophic failure of the material system. Calculations of thermal stress distributions indicate that in all cases the total stress is reduced in reentrant (auxetic cellular solids. This indicates that conventional cellular solids are expected to fail before their auxetic counterparts. Furthermore, both analytical and FE modelling predictions of the brittle crush strength of both auxteic and conventional cellular solids show a relationship with structural stiffness.
Combustion characteristics and turbulence modeling of swirling reacting flow in solid fuel ramjet
Musa, Omer; Xiong, Chen; Changsheng, Zhou
2017-10-01
This paper reviews the historical studies have been done on the solid-fuel ramjet engine and difficulties associated with numerical modeling of swirling flow with combustible gases. A literature survey about works related to numerical and experimental investigations on solid-fuel ramjet as well as using swirling flow and different numerical approaches has been provided. An overview of turbulence modeling of swirling flow and the behavior of turbulence at streamline curvature and system rotation are presented. A new and simple curvature/correction factor is proposed in order to reduce the programming complexity of SST-CC turbulence model. Finally, numerical and experimental investigations on the impact of swirling flow on SFRJ have been carried out. For that regard, a multi-physics coupling code is developed to solve the problems of multi-physics coupling of fluid mechanics, solid pyrolysis, heat transfer, thermodynamics, and chemical kinetics. The connected-pipe test facility is used to carry out the experiments. The results showed a positive impact of swirling flow on SFRJ along with, three correlations are proposed.
HUANG Weifeng; LIAO Chuanjun; LIU Xiangfeng; SUO Shuangfu; LIU Ying; WANG Yuming
2014-01-01
Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants. More accurate models on the operating mechanism of the seals are needed to help improve their performance. The thermal fluid-solid interaction (TFSI) mechanism of the hydrostatic seal is investigated in this study. Numerical models of the flow field and seal assembly are developed. Based on the mechanism for the continuity condition of the physical quantities at the fluid-solid interface, an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method. Dynamic mesh technology is adopted to adapt to the changing boundary shape. Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure. The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data. Using the TFSI model, the behavior of the seal is presented, including mechanical and thermal deformation, and the temperature field. The influences of the rotating speed and differential pressure of the sealing device on the temperature field, which occur widely in the actual use of the seal, are studied. This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals, and the model is validated by full-sized experiments.
Modeling, Simulation, Additive Manufacturing, and Experimental Evaluation of Solid and Porous NiTi
Taheri Andani, Mohsen
In recent years, shape memory alloys (SMAs) have entered a wide range of engineering applications in fields such as aerospace and medical applications. Nickel-titanium (NiTi) is the most commonly used SMAs due to its excellent functional characteristics (shape memory effect and superelasticity behavior). These properties are based on a solid-solid phase transformation between martensite and austenite. Beside these two characteristics, low stiffness, biocompatibility and corrosion properties of NiTi make it an attractive candidate for biomedical applications (e.g., bone plates, bone screws, and vascular stents). It is well know that manufacturing and processing of NiTi is very challenging. The functional properties of NiTi are significantly affected by the impurity level and due to the high titanium content, NiTi are highly reactive. Therefore, high temperature processed parts through methods such as melting and casting which result in increased impurity levels have inadequate structural and functional properties. Furthermore, high ductility and elasticity of NiTi, adhesion, work hardening and spring back effects make machining quite challenging. These unfavorable effects for machining cause significant tool wear along with decreasing the quality of work piece. Recently, additive manufacturing (AM) has gained significant attention for manufacturing NiTi. Since AM can create a part directly from CAD data, it is predicted that AM can overcome most of the manufacturing difficulties. This technique provides the possibility of fabricating highly complex parts, which cannot be processed by any other methods. Curved holes, designed porosity, and lattice like structures are some examples of mentioned complex parts. This work investigates manufacturing superelastic NiTi by selective laser melting (SLM) technique (using PXM by Phenix/3D Systems). An extended experimental study is conducted on the effect of subsequent heat treatments with different aging conditions on phase
Toulhoat, H. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)
1999-07-01
The solid-fluid interface is the place where several phenomena of great technological interest take place. This paper deals with the atomistic simulation of solid-fluid interfaces using the VASP (Vienna Ab Initio Simulation Package) code. VASP uses the electron density functional theory and takes into account the generalized gradient correction. Some examples of application of this method to the modeling of some chemical processes used in petroleum refining are presented: heterogenous catalysis, crystal growth for catalyst support preparation (thiophene hydro-desulfurization on molybdenum sulfide, sulfur poisoning of noble metals, interface tensions in the water/boehmite system). (J.S.)
MEMS for automotive and aerospace applications
Kraft, Michael
2013-01-01
MEMS for automotive and aerospace applications reviews the use of Micro-Electro-Mechanical-Systems (MEMS) in developing solutions to the unique challenges presented by the automotive and aerospace industries.Part one explores MEMS for a variety of automotive applications. The role of MEMS in passenger safety and comfort, sensors for automotive vehicle stability control applications and automotive tire pressure monitoring systems are considered, along with pressure and flow sensors for engine management, and RF MEMS for automotive radar sensors. Part two then goes on to explore MEMS for
Digital radiography in the aerospace industry
Buchanan, R. A.; Bueno, C.; Barry, R. C.; Barker, M. D.
An account is given of the bases of digital radiography (DR), with a view to the identification of NDE systems with the greatest usefulness to the aerospace industry and the nature of the advanced image processing and reconstruction techniques that have been devised thus far. The spatial resolution of any DR system is fundamentally limited by the number of pixels in the digital image and the system field-of-view. Attention is given to the problems of image geometric unsharpness and radiation quantum noise limits, as well as to the potential role of advanced DR in future NDT of aerospace components.
Extensions to the Dynamic Aerospace Vehicle Exchange Markup Language
Brian, Geoffrey J.; Jackson, E. Bruce
2011-01-01
The Dynamic Aerospace Vehicle Exchange Markup Language (DAVE-ML) is a syntactical language for exchanging flight vehicle dynamic model data. It provides a framework for encoding entire flight vehicle dynamic model data packages for exchange and/or long-term archiving. Version 2.0.1 of DAVE-ML provides much of the functionality envisioned for exchanging aerospace vehicle data; however, it is limited in only supporting scalar time-independent data. Additional functionality is required to support vector and matrix data, abstracting sub-system models, detailing dynamics system models (both discrete and continuous), and defining a dynamic data format (such as time sequenced data) for validation of dynamics system models and vehicle simulation packages. Extensions to DAVE-ML have been proposed to manage data as vectors and n-dimensional matrices, and record dynamic data in a compatible form. These capabilities will improve the clarity of data being exchanged, simplify the naming of parameters, and permit static and dynamic data to be stored using a common syntax within a single file; thereby enhancing the framework provided by DAVE-ML for exchanging entire flight vehicle dynamic simulation models.
Stanford Aerospace Research Laboratory research overview
Ballhaus, W. L.; Alder, L. J.; Chen, V. W.; Dickson, W. C.; Ullman, M. A.
1993-02-01
Over the last ten years, the Stanford Aerospace Robotics Laboratory (ARL) has developed a hardware facility in which a number of space robotics issues have been, and continue to be, addressed. This paper reviews two of the current ARL research areas: navigation and control of free flying space robots, and modelling and control of extremely flexible space structures. The ARL has designed and built several semi-autonomous free-flying robots that perform numerous tasks in a zero-gravity, drag-free, two-dimensional environment. It is envisioned that future generations of these robots will be part of a human-robot team, in which the robots will operate under the task-level commands of astronauts. To make this possible, the ARL has developed a graphical user interface (GUI) with an intuitive object-level motion-direction capability. Using this interface, the ARL has demonstrated autonomous navigation, intercept and capture of moving and spinning objects, object transport, multiple-robot cooperative manipulation, and simple assemblies from both free-flying and fixed bases. The ARL has also built a number of experimental test beds on which the modelling and control of flexible manipulators has been studied. Early ARL experiments in this arena demonstrated for the first time the capability to control the end-point position of both single-link and multi-link flexible manipulators using end-point sensing. Building on these accomplishments, the ARL has been able to control payloads with unknown dynamics at the end of a flexible manipulator, and to achieve high-performance control of a multi-link flexible manipulator.
Zhukov Ilya S.
2016-01-01
Full Text Available On the basis of obtained analytical estimate of characteristics of hybrid solid-propellant rocket engine verification of earlier developed physical and mathematical model of processes in a hybrid solid-propellant rocket engine for quasi-steady-state flow regime was performed. Comparative analysis of calculated and analytical data indicated satisfactory comparability of simulation results.
Zhukov Ilya S.; Borisov Boris V.; Bondarchuk Sergey S.; Zhukov Alexander S.
2016-01-01
On the basis of obtained analytical estimate of characteristics of hybrid solid-propellant rocket engine verification of earlier developed physical and mathematical model of processes in a hybrid solid-propellant rocket engine for quasi-steady-state flow regime was performed. Comparative analysis of calculated and analytical data indicated satisfactory comparability of simulation results.
Mohammadi, Bijan; Pironneau, Olivier; Cipolla, Vittorio
2016-01-01
This book presents papers surrounding the extensive discussions that took place from the ‘Variational Analysis and Aerospace Engineering’ workshop held at the Ettore Majorana Foundation and Centre for Scientific Culture in 2015. Contributions to this volume focus on advanced mathematical methods in aerospace engineering and industrial engineering such as computational fluid dynamics methods, optimization methods in aerodynamics, optimum controls, dynamic systems, the theory of structures, space missions, flight mechanics, control theory, algebraic geometry for CAD applications, and variational methods and applications. Advanced graduate students, researchers, and professionals in mathematics and engineering will find this volume useful as it illustrates current collaborative research projects in applied mathematics and aerospace engineering.
刘磊; 刘洪英; 马爱军; 冯雪梅; 石蒙; 董睿; 赵亚雄
2016-01-01
对于处在振动环境中的载人航天某装置复杂结构，设计过程中存在最小化质量、同时最大化一阶整体振动频率的多目标优化问题，可以利用多目标遗传算法（NSGA-II）求解得到Pareto最优解集，但利用NSGA-II 进行求解计算量大，对于复杂结构更甚。为了节省计算时间，提出基于Kriging代理模型的复杂结构多目标优化设计方法，首先通过拉丁超立方采样获得样本点，然后通过样本点创建Kriging模型，最后利用多目标遗传算法求解代理模型得到Pareto最优解集，方便设计师从中选择最优解，优化结果表明本文所述方法合理有效。%For a manned aerospace assembly under vibration environment, there are two objectives in design phase: min mass and max first integral vibration frequency. Usually it can be solved by using multi-objective genetic algorithm (NSGA-II), but the computing amount is too large, especially for complex structure. To drop the computing time of using of NSGA-II in multi-objective structural optimization, a method based on Kriging model was proposed. The method achieved the samples from Latin hypercube design firstly and created the Kriging model based on the samples. Then multi-objective optimization problem could be solved using NSGA-II on the Kriging model and got the Pareto set finally. The results verify the effectiveness and practicability of the method.
Graciele Viccini
2003-01-01
Full Text Available A mathematical model is developed for converting between the two measurement bases commonly used in the construction of growth profiles in solid-state fermentation, namely absolute mass ratio m(dry biomass/m(initial dry matter and relative mass ratio m(dry biomass/m(dry matter. These are not equivalent, due to the loss of dry matter as CO2 during the fermentation. The model is equally applicable to any biomass component used in indirect measurements of growth, such as protein. Use of the model to convert absolute mass ratio of the biomass profiles for the growth of Rhizopus oligosporus to a relative basis gave profiles that agreed well with the experimentally determined relative biomass profiles. This agreement was obtained for three different fermentations using the same set of parameter values in the model, namely a yield coefficient of m(protein/m(dry substrate = 0.2 g/g and a maintenance coefficient of zero, giving confidence in the reliability of the model. The model was then used to show that the measurement basis used can affect the form of the curve and therefore can also affect the conclusion drawn about the type of kinetics shown by the organism, with the extent of this effect depending on the length of time that growth occurs and the values of the yield and maintenance coefficients. This work shows that great care must be taken in drawing conclusions about growth kinetics in solid-state fermentation.
Modeling conversion and transport phenomena in solid-state fermentation: a review and perspectives.
Rahardjo, Yovita S P; Tramper, Johannes; Rinzema, Arjen
2006-01-01
Solid-state fermentation (SSF) is accompanied inevitably by development of concentration and temperature gradients within the substrate particles and microbial biofilms. These gradients are needed for driving the transport of substrates and products. In addition, concentration gradients have been suggested to be crucial for obtaining the characteristics that define the products of SSF; nevertheless, gradients are also known to result in reduced productivity and unwanted side reactions. Solid-state fermentations are generally batch processes and this further complicates their understanding as conditions change with time. Mathematical models are therefore needed for improving the understanding of SSF processes and allowing their manipulation to achieve the desired outcomes. Existing models of SSF processes describe coupled substrate conversion and diffusion and the consequent microbial growth. Existing models disregard many of the significant phenomena that are known to influence SSF. As a result, available models cannot explain the generation of the numerous products that form during any SSF process and the outcome of the process in terms of the characteristics of the final product. This review critically evaluates the proposed models and their experimental validation. In addition, important issues that need to be resolved for improved modeling of SSF are discussed.
Jiyuan Zhang
2014-09-01
Full Text Available The application of headspace-solid phase microextraction (HS-SPME has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and chemical reactor modeling was developed, describing the kinetic behavior of aroma active compounds extracted by SPME from two different food model systems, i.e., a semi-solid food and a liquid food. The model accounted for both adsorption and release of the analytes from SPME fiber, which occurred simultaneously but were counter-directed. The model had four parameters and their estimated values were found to be more reproducible than the direct measurement of the compounds themselves by instrumental analysis. With the relative standard deviations (RSD of each parameter less than 5% and root mean square error (RMSE less than 0.15, the model was proved to be a robust one in estimating the release of a wide range of low molecular weight acetates at three environmental temperatures i.e., 30, 40 and 60 °C. More insights of SPME behavior regarding the small molecule analytes were also obtained through the kinetic parameters and the model itself.
Application of fractional calculus to modeling transient combustion of solid propellants
Kulish, Vladimir; Horák, Vladimír; Duc, Linh Do; Lukáč, Tomáš
2017-01-01
It was Zel'dovich, who first considered the transient combustion problem of solid propellants. Some more detailed models of that process have been developed afterwards. However, until today, numerical methods remain the prevailing tool for modeling unsteady combustion processes. In this work, it has been demonstrated that at least one of the problems of the unsteady combustion theory, which previously investigated numerically, can be treated analytically by means of fractional calculus. The solution for the unsteady speed of combustion thus derived is then compared with the solution obtained by numerical means in previous studies. The comparison shows a good agreement between those results, especially for small values of time.
Anisotropic solid-liquid interface kinetics in silicon: an atomistically informed phase-field model
Bergmann, S.; Albe, K.; Flegel, E.; Barragan-Yani, D. A.; Wagner, B.
2017-09-01
We present an atomistically informed parametrization of a phase-field model for describing the anisotropic mobility of liquid-solid interfaces in silicon. The model is derived from a consistent set of atomistic data and thus allows to directly link molecular dynamics and phase field simulations. Expressions for the free energy density, the interfacial energy and the temperature and orientation dependent interface mobility are systematically fitted to data from molecular dynamics simulations based on the Stillinger-Weber interatomic potential. The temperature-dependent interface velocity follows a Vogel-Fulcher type behavior and allows to properly account for the dynamics in the undercooled melt.
Void damage model and service life prediction for solid high polymer
无
2001-01-01
Based on the analysis of three void damage variety models, this note presents ( i ) a method that regards the void content as a damage variation of the grain and ( ii ) a geometric model for micro-unit of void damage. Equations of the void damage variety containing void content are analyzed. This work is focused on the measurement of internal damage level and the damage variety estimation is directly related to the life predication in the practical engineering applications. Nowadays, the critical service life of the solid grain/polymers is usually presumed at domestic and international level. The strength or strain reduction of 20%or the stabilizer consumption of 50% is generally regarded as a critical storage life of the solid grain/polymers, and the service life is predicted by the extrapolation method on Anhenius formula. The applications, however, show that the above method is unreliable and has significant errors. With the aid of the discontiguous automatic measuring device of real time volume deformation and void content, the master curve of void damage variety, the storage service life and the surplus life of a solid rocket grain are obtained. Since the critical storage life has been measured, and the accuracy of the service life prediction has been greatly increased. It is a novel ideal and a break-through technique.
A two-fluid model for reactive dilute solid-liquid mixtures with phase changes
Reis, Martina Costa; Wang, Yongqi
2016-12-01
Based on the Eulerian spatial averaging theory and the Müller-Liu entropy principle, a two-fluid model for reactive dilute solid-liquid mixtures is presented. Initially, some averaging theorems and properties of average quantities are discussed and, then, averaged balance equations including interfacial source terms are postulated. Moreover, constitutive equations are proposed for a reactive dilute solid-liquid mixture, where the formation of the solid phase is due to a precipitation chemical reaction that involves ions dissolved in the liquid phase. To this end, principles of constitutive theory are used to propose linearized constitutive equations that account for diffusion, heat conduction, viscous and drag effects, and interfacial deformations. A particularity of the model is that the mass interfacial source term is regarded as an independent constitutive variable. The obtained results show that the inclusion of the mass interfacial source term into the set of independent constitutive variables permits to easily describe the phase changes associated with precipitation chemical reactions.
A two-fluid model for reactive dilute solid-liquid mixtures with phase changes
Reis, Martina Costa; Wang, Yongqi
2017-03-01
Based on the Eulerian spatial averaging theory and the Müller-Liu entropy principle, a two-fluid model for reactive dilute solid-liquid mixtures is presented. Initially, some averaging theorems and properties of average quantities are discussed and, then, averaged balance equations including interfacial source terms are postulated. Moreover, constitutive equations are proposed for a reactive dilute solid-liquid mixture, where the formation of the solid phase is due to a precipitation chemical reaction that involves ions dissolved in the liquid phase. To this end, principles of constitutive theory are used to propose linearized constitutive equations that account for diffusion, heat conduction, viscous and drag effects, and interfacial deformations. A particularity of the model is that the mass interfacial source term is regarded as an independent constitutive variable. The obtained results show that the inclusion of the mass interfacial source term into the set of independent constitutive variables permits to easily describe the phase changes associated with precipitation chemical reactions.
Kaniowski, Robert; Poniewski, Mieczysław
2013-12-01
Heat exchangers of different types find application in power systems based on solid oxide fuel cells (SOFC). Compact plate fin heat exchangers are typically found to perfectly fit systems with power output under 5 kWel. Micro-combined heat and power (micro-CHP) units with solid oxide fuel cells can exhibit high electrical and overall efficiencies, exceeding 85%, respectively. These values can be achieved only when high thermal integration of a system is assured. Selection and sizing of heat exchangers play a crucial role and should be done with caution. Moreover, performance of heat exchangers under variable operating conditions can strongly influence efficiency of the complete system. For that reason, it becomes important to develop high fidelity mathematical models allowing evaluation of heat exchangers under modified operating conditions, in high temperature regimes. Prediction of pressure and temperatures drops at the exit of cold and hot sides are important for system-level studies. Paper presents dedicated mathematical model used for evaluation of a plate fin heat exchanger, operating as a part of micro-CHP unit with solid oxide fuel cells.
A novel numerical model for passively mode-locked solid-state lasers
Leitner, A.; Aussenegg, F.; Lippitsch, M.; Roschger, E.
1983-04-01
Numerical computer models could be of high value in testing ideas for improving passive mode locking. Most of the known models for solid-state lasers lack realistic quantitative results, however. A new model is presented, using a rate-equation approach which has been refined to include interference effects by using field amplitudes and phases instead of energies. Also, the saturable absorber is treated by rate equations. With this model, a rather complete description of the pulse evolution is possible. The influence of various parameters on the mode-locking quality is calculated. The model is also capable of reliably describing processes based mainly on interference effects, like the action of external subresonators.
Microscopic model for the neutron dynamic structure factor of solid methane in phase II
Shin Yunchang, E-mail: yunchang.shin@yale.ed [Department of Physics, Indiana University Bloomington, IN 47408 (United States); Department of Physics, Yale University, New Haven, CT 06520 (United States); Mike Snow, W.; Liu, C.Y.; Lavelle, C.M.; Baxter, David V. [Department of Physics, Indiana University Bloomington, IN 47408 (United States)
2010-08-21
We have constructed a microscopic model for the neutron dynamic structure factor S(Q,{omega}) of solid methane in phase II. We expect this model to apply for neutron energies below 1 eV at pressures near 1 bar and temperatures below 20 K where methane possesses both free rotation and hindered rotation modes of the tetrahedral molecules in the unit cell. The model treats the motions of molecular translations, intra-molecular vibrations and the free and hindered rotations of methane molecule as independent. Total scattering cross-sections calculated from the model agree with the cross-section measurements for incident neutron energies of 0.5 meV-1 eV. The effective density of states is extracted from the model. We also present the quantitative calculation of the separate contributions of the two different rotational modes to the inelastic cross-section for different methane temperatures in phase II.
Control oriented modeling of ejector in anode gas recirculation solid oxygen fuel cell systems
Zhu Yinhai, E-mail: yinhai.zhu@gmail.co [School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Li Yanzhong, E-mail: yzli-epe@mail.xjtu.edu.c [School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Cai Wenjian [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
2011-04-15
A one-equation model is proposed for fuel ejector in anode gas recirculation solid oxide fuel cell (SOFC) system. Firstly, the fundamental governing equations are established by employing the thermodynamic, fluid dynamic principles and chemical constraints inside the ejector; secondly, the one-equation model is derived by using the parameter analysis and lumped-parameter method. Finally, the computational fluid dynamics (CFD) technique is employed to obtain the source data for determining the model parameters. The effectiveness of the model is studied under a wide range of operation conditions. The effect of ejector performance on the anode gas recirculation SOFC system is also discussed. The presented model, which only contains four constant parameters, is useful in real-time control and optimization of fuel ejector in the anode gas recirculation SOFC system.
Solid Waste Projection Model: Database User`s Guide. Version 1.4
Blackburn, C.L.
1993-10-01
The Solid Waste Projection Model (SWPM) system is an analytical tool developed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford Company (WHC) specifically to address Hanford solid waste management issues. This document is one of a set of documents supporting the SWPM system and providing instructions in the use and maintenance of SWPM components. This manual contains instructions for using Version 1.4 of the SWPM database: system requirements and preparation, entering and maintaining data, and performing routine database functions. This document supports only those operations which are specific to SWPM database menus and functions and does not Provide instruction in the use of Paradox, the database management system in which the SWPM database is established.
Microscopic model for chemical etchability along radiation damage paths in solids
Mukhtar Ahmed RANA
2008-01-01
It would be very interesting to develop a picture about removal of atoms from the radiation damaged paths or latent nuclear tracks and undamaged bulk material in track detectors. Here, theory of chemical etching is described briefly and a new model for chemical etching along radiation damaged paths in solids is developed based on basic scientific facts and valid assumptions. Dependence of chemical etching on radiation damage intensity and etching conditions is discussed. A new parameter for etching along radiation damaged paths is introduced, which is useful for investigation of relationship between chemical etchability and radiation damage in a solid. Results and discussion presented here are also useful for further development of nuclear waste immobilization.
Lakhdari, Fouad; Osmani, Ismahen; Tabet, Saida
2015-09-01
Thermal management in solid state laser is a challenge to the high power laser industry's ability to provide continued improvements in device and system performance. In this work an investigation of heat generation and thermo-mechanical effect in a high-power Nd:YAG and Yb:YAG cylindrical-type solid state laser pumped longitudinally with different power by fibre coupled laser diode is carried out by numerical simulation based on the finite element method (FEM). Impact of the dopant concentration on the power conversion efficiency is included in the simulation. The distribution of the temperature inside the lasing material is resolute according to the thermal conductivity. The thermo-mechanical effect is explored as a function of pump power in order to determine the maximum pumping power allowed to prevent the crystal's fracture. The presented simulations are in broad agreement with analytical solutions; provided that the boundary condition of the pump induced heat generation is accurately modelled.
Modified lattice-gas model for the gas-liquid-solid phase diagram
Imry, Yoseph; Schwartz, Moshe
1980-04-01
Crystalline order parameters related to the localization of the particles within the cells are introduced into the usual lattice-gas model. The coupling of these order parameters to the usual liquid-gas transition is shown to produce, in the simplest approximation, phase diagrams of qualitatively correct shapes. The Goldstone modes of the solid are retained in this picture. The Landau theory of melting is reviewed and shown to always lead to a first-order solid-fluid transition. The question of the possibility of the transition becoming second order due to fluctuations is discussed qualitatively. This possibility is shown to depend on the relative sizes of the first-order transition and the critical region of the fluctuations.
Viscosity of fused silica and thermal noise from the standard linear solid model
Kondratiev, N. M.; Gorodetsky, M. L.
2016-10-01
The fluctuation-dissipation theorem states that each source of dissipation yields corresponding fluctuations. The most obvious source of dissipation in liquids is viscosity—internal friction between layers of matter. However, this property also exists in solid materials in a glass state, i.e., an amorphous substance that cannot become a crystal due to high viscosity. Fused silica is a low-loss glass material used in many interferometric applications demanding high stability, such as Fabry-Perot etalons and gravitational-wave detector mirrors and suspensions. Very high viscosity (from 1 017 to 1 040 Pa s in the literature) can be the source of additional noise and can influence the performance of such devices. We show that fused silica may be described with the standard linear solid model of viscoelastisity and present a method to estimate this type of noise.
3D modeling and simulation of the thermal performance of solid cyclotron targets
Avila-Rodriguez, M.A.; Sader, J.A.; McQuarrie, S.A. [Alberta Univ., Edmonton PET Centre, Cross Cancer Institute, AB (Canada); McQuarrie, S.A. [Alberta Univ., Faculty of Medicine and Dentistry, Div. of Oncologic Imaging, Edmonton, AB (Canada)
2007-07-01
COMSOL Multiphysics was used to model and simulate the thermal performance of solid targets irradiated with charged particles. Parametric solutions for beam power densities in the range from 1.5 10{sup 5} to 1.5 10{sup 6} W/m{sup 2} and cooling water flow velocities from 0.2 to 4.0 m/s were obtained for different plate materials. Results showed that materials with a high thermal conductivity to heat capacity ratio behave better in cooling dynamic systems requiring fast dissipation of heat. Results also showed that water flow rates greater than 2.6 L/min do not noticeably improve the heat dissipation of solid targets irradiated with charged particles. (authors)
A two-phase solid/fluid model for dense granular flows including dilatancy effects
Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Koné, El-Hadj; Narbona-Reina, Gladys
2016-04-01
Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [{Iverson et al.}, 2010]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure [{Bouchut et al.}, 2016]. The model is derived from a 3D two-phase model proposed by {Jackson} [2000] based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work [{Bouchut et al.}, 2015]. In particular, {Pitman and Le} [2005] replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's model by closing the mixture equations by a weak compressibility relation following {Roux and Radjai} [1998]. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To
Surface clogging process modeling of suspended solid during urban stormwater aquifer recharge
Wang, Z.
2012-04-01
Aquifer recharge (AR), which uses urban stormwater, is an effective technique to control the negative environmental effects of groundwater over-exploitation. While AR is widely used worldwide, clogging problems in infiltration systems remain the key restricting factor in broadening its practice. At present, quantitative understanding of the clogging process is still very poor. A laboratory study was conducted to understand surface physical clogging processes, with the primary aim of developing a model for predicting suspended solid clogging process before the AR projects start. The experiments investigated the clogging characteristics of different suspended solids size in recharge water by using a series of 1-D fine quartz sand columns. The results showed that the smaller the suspended particles in recharge water, the farther the distance of movement and the larger the scope of clogging in porous media. Clogging extents in fine sand were 1 cm, with suspended particle sizes ranging from 0.075 mm to 0.0385 mm, and 2 cm, with particles less than 0.0385 mm. In addition, clogging development occurred faster for smaller suspended solid particles. It took large-, medium-, and small-sized particles 48, 42, and 36 h, respectively, to reach pre-determined clogging standards. An empirical formula and its recursive model for the surface clogging evolution process were derived based on the series of experiments. The verification results obtained by stormwater recharge into the fine sand demonstrated that the model could reflect the real conditions of surface clogging processes. Parameter sensitivity of the model was determined, and results showed that the estimated parameters in model would not cause obvious errors for clogging prediction.