NASA Technical Reports Server (NTRS)
2001-01-01
Langley Research Center has licensed a new high-temperature polyimide with versatile applications to Unitech LLC, of Hampton, Virginia, and J. D. Lincoln, Inc., of Costa Mesa, California. Through a Memorandum of Agreement (MOA) and its license, Unitech, a client of the NASA Hampton Roads Technology Incubator (HRTI), is now selling the new polyimide, better known as RP46. Dr. Ruth Pater, of NASA Langley, developed RP46 for aerospace applications. The material was designed for re-entry vehicles and high-temperature engine components; however, its versatile nature makes it applicable as a molding, adhesive, coating, composite matrix resin, foam, or film. Available in liquid and powder forms, RP46 can also be fabricated over mesh for use in molds. RP46 presents a profitable option to manufacturers, because the ease of manufacturing the resin and the reduction in curing time saves money. Consumers save money because RP46 is more durable than similar products that are susceptible to microcracking when used as a coating or adhesive in high-temperature situations and often required reapplication. The chances of microcracking are significantly reduced with RP46 because of its unsurpased ability to resist heat and corrosion.
Adkin, A; Bernier, D; Santymire, R M
2012-08-01
The Sichuan takin (takin; Budorcas taxicolor tibetana) is distributed in the Gansu and Sichuan providences of southern China and along eastern Tibet. Because of their ecology, few data on takin reproductive biology exist, with the exception of its mating season in the Sichuan province, which occurs from July through August. Therefore, the objectives were to: 1) characterize reproductive hormones in zoo-housed male and female takin, including pregnancy in the female, using non-invasive fecal steroid hormonal monitoring; 2) characterize behaviors of zoo-housed takin, emphasizing reproductive behaviors and activity budget; and 3) assess the influence of season on births in North America and reproductive hormonal and behavioral activity. Fecal samples were collected 3 to 5 times per week from two adult males and three adult females. Extracted hormones were analyzed using an enzyme immunoassay for progestagen and androgen concentrations. Behavioral observations were collected for 2 yrs using an ethogram. In this study, season affected reproduction, specifically birth occurrences, reproductive cyclicity in females and androgen production in males. The duration of the estrous cycle was approximately 35 d and cycles occurred June through December. Androgen concentrations peaked in May through August. Season did not influence behavior; however, age and sex may affect some behaviors, including activity level, foraging and drinking, social affiliative behavior, and visibility from the visitor's viewpoint. In conclusion, fecal hormonal and behavioral analyses can provide information for management and conservation of this herd species.
Li, Wang; Huan, Xiajuan; Zhou, Ying; Ma, Qingyi; Chen, Yulin
2009-06-12
A bacterial strain with high cellulase activity was isolated of feces sample of Golden Takin (Budorcas taxicolor Bedfordi). The bacterium was classified and designated Bacillus subtilis LN by morphological and 16SrDNA gene sequence analysis. Two putative cellulase genes, CelL15 and CelL73, were simultaneously cloned from the isolated strain by PCR. The putative gene CelL15 consisted of an open reading frame (ORF) of 1470 nucleotides and encoded a protein of 490 amino acids with a molecular weight of 54 kDa. The CelL73 gene consisted of an open reading frame (ORF) of 741 nucleotides and encoded a protein of 247 amino acids with a molecular weight of 27 kDa. Both genes were purified and cloned into pET-28a for expression in Escherichia coli BL21 (DE3). The ability of E. coli to degrade cellulose was enhanced when the two recombinants were cultured together.
Multimedia Matrix: A Cognitive Strategy for Designers.
ERIC Educational Resources Information Center
Sherry, Annette C.
This instructional development project evaluates the effect of a matrix-based strategy to assist multimedia authors in acquiring and applying principles for effective multimedia design. The Multimedia Matrix, based on the Park and Hannafin "Twenty Principles and Implications for Interactive Multimedia" design, displays a condensed…
Yao, Gang; Li, Yanhong; Li, Dayong; Williams, Peter; Hu, Jie
2016-07-01
The takin (Budorcas taxicolor) is an Endangered ungulate. We analyzed the variation within mtDNA control region sequences of takin populations in the Qinling Mountains, the Minshan Mountains and the confluence of these two mountain ranges. We did not find any shared haplotypes among the populations. We observed apparent variation in the control region length among the three populations, and independent population expansions in the late of Pleistocene, which suggests these populations may have independent evolutionary histories. We found only one haplotype, and the lowest measures of genetic diversity (h = 0; π = 0) in the population from the confluent zone, which suggests populations in the confluent zone may have grown from small founder populations and gene flow with other populations has ceased. Based on their phylogenetic relationships, we concluded that the takin population in the confluent zone was in the same clade as the Tangjiahe population, which suggests that these takin populations are Sichuan takin (Budorcas taxicolor tibetana).
Teaching Improvement Model Designed with DEA Method and Management Matrix
ERIC Educational Resources Information Center
Montoneri, Bernard
2014-01-01
This study uses student evaluation of teachers to design a teaching improvement matrix based on teaching efficiency and performance by combining management matrix and data envelopment analysis. This matrix is designed to formulate suggestions to improve teaching. The research sample consists of 42 classes of freshmen following a course of English…
Analytical techniques for instrument design - matrix methods
Robinson, R.A.
1997-09-01
We take the traditional Cooper-Nathans approach, as has been applied for many years for steady-state triple-axis spectrometers, and consider its generalisation to other inelastic scattering spectrometers. This involves a number of simple manipulations of exponentials of quadratic forms. In particular, we discuss a toolbox of matrix manipulations that can be performed on the 6- dimensional Cooper-Nathans matrix: diagonalisation (Moller-Nielsen method), coordinate changes e.g. from ({Delta}k{sub I},{Delta}k{sub F} to {Delta}E, {Delta}Q & 2 dummy variables), integration of one or more variables (e.g. over such dummy variables), integration subject to linear constraints (e.g. Bragg`s Law for analysers), inversion to give the variance-covariance matrix, and so on. We show how these tools can be combined to solve a number of important problems, within the narrow-band limit and the gaussian approximation. We will argue that a generalised program that can handle multiple different spectrometers could (and should) be written in parallel to the Monte-Carlo packages that are becoming available. We will also discuss the complementarity between detailed Monte-Carlo calculations and the approach presented here. In particular, Monte-Carlo methods traditionally simulate the real experiment as performed in practice, given a model scattering law, while the Cooper-Nathans method asks the inverse question: given that a neutron turns up in a particular spectrometer configuration (e.g. angle and time of flight), what is the probability distribution of possible scattering events at the sample? The Monte-Carlo approach could be applied in the same spirit to this question.
Matrix Transfer Function Design for Flexible Structures: An Application
NASA Technical Reports Server (NTRS)
Brennan, T. J.; Compito, A. V.; Doran, A. L.; Gustafson, C. L.; Wong, C. L.
1985-01-01
The application of matrix transfer function design techniques to the problem of disturbance rejection on a flexible space structure is demonstrated. The design approach is based on parameterizing a class of stabilizing compensators for the plant and formulating the design specifications as a constrained minimization problem in terms of these parameters. The solution yields a matrix transfer function representation of the compensator. A state space realization of the compensator is constructed to investigate performance and stability on the nominal and perturbed models. The application is made to the ACOSSA (Active Control of Space Structures) optical structure.
Airbreathing/Rocket Single-Stage-to-Orbit Design Matrix
NASA Technical Reports Server (NTRS)
Hunt, James L.
1995-01-01
A definitive design/performance study was performed on a single-stage-to-orbit (SSTO) airbreathing propelled orbital vehicle with rocket propulsion augmentation in the Access to Space activities during 1993. A credible reference design was established, but by no means an optimum. The results supported the viability of SSTO airbreathing/rocket vehicles for operational scenarios and indicated compelling reasons to continue to explore the design matrix. This paper will (1) summarize the Access to Space design activity from the SSTO airbreathing/rocket perspective, (2) present an airbreathing/rocket SSTO design matrix established for continued optimization of the design space, and (3) focus on the compelling reasons for airbreathing vehicles in Access to Space scenarios.
A Matrix-Free Algorithm for Multidisciplinary Design Optimization
NASA Astrophysics Data System (ADS)
Lambe, Andrew Borean
Multidisciplinary design optimization (MDO) is an approach to engineering design that exploits the coupling between components or knowledge disciplines in a complex system to improve the final product. In aircraft design, MDO methods can be used to simultaneously design the outer shape of the aircraft and the internal structure, taking into account the complex interaction between the aerodynamic forces and the structural flexibility. Efficient strategies are needed to solve such design optimization problems and guarantee convergence to an optimal design. This work begins with a comprehensive review of MDO problem formulations and solution algorithms. First, a fundamental MDO problem formulation is defined from which other formulations may be obtained through simple transformations. Using these fundamental problem formulations, decomposition methods from the literature are reviewed and classified. All MDO methods are presented in a unified mathematical notation to facilitate greater understanding. In addition, a novel set of diagrams, called extended design structure matrices, are used to simultaneously visualize both data communication and process flow between the many software components of each method. For aerostructural design optimization, modern decomposition-based MDO methods cannot efficiently handle the tight coupling between the aerodynamic and structural states. This fact motivates the exploration of methods that can reduce the computational cost. A particular structure in the direct and adjoint methods for gradient computation. motivates the idea of a matrix-free optimization method. A simple matrix-free optimizer is developed based on the augmented Lagrangian algorithm. This new matrix-free optimizer is tested on two structural optimization problems and one aerostructural optimization problem. The results indicate that the matrix-free optimizer is able to efficiently solve structural and multidisciplinary design problems with thousands of variables and
A Matrix-Free Algorithm for Multidisciplinary Design Optimization
NASA Astrophysics Data System (ADS)
Lambe, Andrew Borean
Multidisciplinary design optimization (MDO) is an approach to engineering design that exploits the coupling between components or knowledge disciplines in a complex system to improve the final product. In aircraft design, MDO methods can be used to simultaneously design the outer shape of the aircraft and the internal structure, taking into account the complex interaction between the aerodynamic forces and the structural flexibility. Efficient strategies are needed to solve such design optimization problems and guarantee convergence to an optimal design. This work begins with a comprehensive review of MDO problem formulations and solution algorithms. First, a fundamental MDO problem formulation is defined from which other formulations may be obtained through simple transformations. Using these fundamental problem formulations, decomposition methods from the literature are reviewed and classified. All MDO methods are presented in a unified mathematical notation to facilitate greater understanding. In addition, a novel set of diagrams, called extended design structure matrices, are used to simultaneously visualize both data communication and process flow between the many software components of each method. For aerostructural design optimization, modern decomposition-based MDO methods cannot efficiently handle the tight coupling between the aerodynamic and structural states. This fact motivates the exploration of methods that can reduce the computational cost. A particular structure in the direct and adjoint methods for gradient computation motivates the idea of a matrix-free optimization method. A simple matrix-free optimizer is developed based on the augmented Lagrangian algorithm. This new matrix-free optimizer is tested on two structural optimization problems and one aerostructural optimization problem. The results indicate that the matrix-free optimizer is able to efficiently solve structural and multidisciplinary design problems with thousands of variables and
Designing Cure Cycles for Matrix/Fiber Composite Parts
NASA Technical Reports Server (NTRS)
Hou, Tan-Hung
2006-01-01
A methodology has been devised for designing cure cycles to be used in the fabrication of matrix/fiber composite parts (including laminated parts). As used here, cure cycles signifies schedules of elevated temperature and pressure as functions of time, chosen to obtain desired rates of chemical conversion of initially chemically reactive matrix materials and to consolidate the matrix and fiber materials into dense solids. Heretofore, cure cycles have been designed following an empirical, trial-and-error approach, which cannot be relied upon to yield optimum results. In contrast, the present methodology makes it possible to design an optimum or nearly optimum cure cycle for a specific application. Proper design of a cure cycle is critical for achieving consolidation of a reactive matrix/fiber layup into a void-free laminate. A cure cycle for a composite containing a reactive resin matrix usually consists of a two-stage ramp-and-hold temperature profile. The temperature and the duration of the hold for each stage are unique for a given composite material. The first, lower-temperature ramp-and hold stage is called the B stage in composite- fabrication terminology. At this stage, pressure is not applied, and volatiles (solvents and reaction by-products) are free to escape. The second, higher-temperature stage is for final forced consolidation.
Airbreathing Hypersonic Vision-Operational-Vehicles Design Matrix
NASA Technical Reports Server (NTRS)
Hunt, James L.; Pegg, Robert J.; Petley, Dennis H.
1999-01-01
This paper presents the status of the airbreathing hypersonic airplane and space-access vision-operational-vehicle design matrix, with emphasis on horizontal takeoff and landing systems being studied at Langley; it reflects the synergies and issues, and indicates the thrust of the effort to resolve the design matrix including Mach 5 to 10 airplanes with global-reach potential, pop-up and dual-role transatmospheric vehicles and airbreathing launch systems. The convergence of several critical systems/technologies across the vehicle matrix is indicated. This is particularly true for the low speed propulsion system for large unassisted horizontal takeoff vehicles which favor turbines and/or perhaps pulse detonation engines that do not require LOX which imposes loading concerns and mission flexibility restraints.
Airbreathing Hypersonic Vision-Operational-Vehicles Design Matrix
NASA Technical Reports Server (NTRS)
Hunt, James L.; Pegg, Robert J.; Petley, Dennis H.
1999-01-01
This paper presents the status of the airbreathing hypersonic airplane and space-access vision-operational-vehicle design matrix, with emphasis on horizontal takeoff and landing systems being, studied at Langley, it reflects the synergies and issues, and indicates the thrust of the effort to resolve the design matrix including Mach 5 to 10 airplanes with global-reach potential, pop-up and dual-role transatmospheric vehicles and airbreathing launch systems. The convergence of several critical systems/technologies across the vehicle matrix is indicated. This is particularly true for the low speed propulsion system for large unassisted horizontal takeoff vehicles which favor turbines and/or perhaps pulse detonation engines that do not require LOX which imposes loading concerns and mission Flexibility restraints.
Control-matrix approach to stellarator design and control
Mynick, H.E.; Pomphrey, N.
2000-02-09
The full space Z always equal to {l{underscore}brace}Zj=1,..Nz{r{underscore}brace} of independent variables defining a stellarator configuration is large. To find attractive design points in this space, or to understand operational flexibility about a given design point, one needs insight into the topography in Z-space of the physics figures of merit Pi which characterize the machine performance, and means of determining those directions in Z-space which give one independent control over the Pi, as well as those which affect none of them, and so are available for design flexibility. The control matrix (CM) approach described here provides a mathematical means of obtaining these. In this work, the authors describe the CM approach and use it in studying some candidate Quasi-Axisymmetric (QA) stellarator configurations the NCSX design group has been considering. In the process of the analysis, a first exploration of the topography of the configuration space in the vicinity of these candidate systems has been performed, whose character is discussed.
Microstrip Butler matrix design and realization for 7 T MRI.
Yazdanbakhsh, Pedram; Solbach, Klaus
2011-07-01
This article presents the design and realization of 8 × 8 and 16 × 16 Butler matrices for 7 T MRI systems. With the focus on low insertion loss and high amplitude/phase accuracy, the microstrip line integration technology (microwave-integrated circuit) was chosen for the realization. Laminate material of high permittivity (ε(r) = 11) and large thickness (h = 3.2 mm) is shown to allow the best trade-off of circuit board size versus insertion loss, saving circuit area by extensive folding of branch-line coupler topology and meandering phase shifter and connecting strip lines and reducing mutual coupling of neighboring strip lines by shield structures between strip lines. With this approach, 8 × 8 Butler matrices were produced in single boards of 310 mm × 530 mm, whereas the 16 × 16 Butler matrices combined two submatrices of 8 × 8 with two smaller boards. Insertion loss was found at 0.73 and 1.1 dB for an 8 × 8 matrix and 16 × 16 matrix, respectively. Measured amplitude and phase errors are shown to represent highly pure mode excitation with unwanted modes suppressed by 40 and 35 dB, respectively. Both types of matrices were implemented with a 7 T MRI system and 8- and 16-element coil arrays for RF mode shimming experiments and operated successfully with 8 kW of RF power.
Recent advances in the design of matrix metalloprotease inhibitors.
Matter, Hans; Schudok, Manfred
2004-07-01
Inhibition of matrix metalloproteases (MMPs) for the treatment of diseases, such as cancer, arthritis and other diseases associated with tissue remodeling, has become an area of intense interest in the pharmaceutical industry in recent years. Despite tremendous efforts over the last decade to explore individual members of this target family, along with multiple inhibitor classes, simple and effective drugs for inhibiting individual MMPs have not yet emerged. This review highlights the major developments in research into MMPs and their inhibitors, from the recent medicinal chemistry literature, with a focus on structure-based design, selectivity and pharmacokinetic (PK) properties. The increasing availability of high-resolution X-ray crystal structures for many members of this protein family makes MMPs ideally suited for structure-based design approaches, which are now routinely used in this area. The most challenging aspect of lead optimization for MMP inhibitors is in finding candidates having acceptable pharmacological, PK and selectivity profiles. Clinical trials in cancer giving disappointing results have led to discussions on how to gain adequate MMP selectivity in order to minimize side effects. Unfortunately, careful analysis of X-ray crystal structures has not suggested any simple solutions. These areas collectively constitute the main challenges in the current search for orally available MMP inhibitors, and will be discussed in this review.
Designing an extracellular matrix protein with enhanced mechanical stability
Ng, Sean P.; Billings, Kate S.; Ohashi, Tomoo; Allen, Mark D.; Best, Robert B.; Randles, Lucy G.; Erickson, Harold P.; Clarke, Jane
2007-01-01
The extracellular matrix proteins tenascin and fibronectin experience significant mechanical forces in vivo. Both contain a number of tandem repeating homologous fibronectin type III (fnIII) domains, and atomic force microscopy experiments have demonstrated that the mechanical strength of these domains can vary significantly. Previous work has shown that mutations in the core of an fnIII domain from human tenascin (TNfn3) reduce the unfolding force of that domain significantly: The composition of the core is apparently crucial to the mechanical stability of these proteins. Based on these results, we have used rational redesign to increase the mechanical stability of the 10th fnIII domain of human fibronectin, FNfn10, which is directly involved in integrin binding. The hydrophobic core of FNfn10 was replaced with that of the homologous, mechanically stronger TNfn3 domain. Despite the extensive substitution, FNoTNc retains both the three-dimensional structure and the cell adhesion activity of FNfn10. Atomic force microscopy experiments reveal that the unfolding forces of the engineered protein FNoTNc increase by ≈20% to match those of TNfn3. Thus, we have specifically designed a protein with increased mechanical stability. Our results demonstrate that core engineering can be used to change the mechanical strength of proteins while retaining functional surface interactions. PMID:17535921
Blade system design studies volume II : preliminary blade designs and recommended test matrix.
Griffin, Dayton A.
2004-06-01
As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts, LLC is performing a Blade System Design Study (BSDS) concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The BSDS Volume I project report addresses issues and constraints identified to scaling conventional blade designs to the megawatt size range, and evaluated candidate materials, manufacturing and design innovations for overcoming and improving large blade economics. The current report (Volume II), presents additional discussion of materials and manufacturing issues for large blades, including a summary of current trends in commercial blade manufacturing. Specifications are then developed to guide the preliminary design of MW-scale blades. Using preliminary design calculations for a 3.0 MW blade, parametric analyses are performed to quantify the potential benefits in stiffness and decreased gravity loading by replacement of a baseline fiberglass spar with carbon-fiberglass hybrid material. Complete preliminary designs are then presented for 3.0 MW and 5.0 MW blades that incorporate fiberglass-to-carbon transitions at mid-span. Based on analysis of these designs, technical issues are identified and discussed. Finally, recommendations are made for composites testing under Part I1 of the BSDS, and the initial planned test matrix for that program is presented.
1986-01-01
MATRIX AND THE (0 REPRESENTATIVE DESIGN OF EXPERIMENTS .4 Kenneth R. Hammond, Robert M. Hamm and Janet Grassia ) 13 LA.’I.7 A GENERALIZING OVER...CONDITIONS BY COMBINING THE MULTITKAIT MULTIMETHOD MATRIX AND THE 46_6 REPRESENTATIVE DESIGN OF EXPERIMENTS Kenneth R. Hammond, Robert M. Hamm and Janet...and the Representative Design of Experiments 6. PERFORMINGOn. REPORT NUMER 7. AUTHOR(@) S. CONTRACT oR GRANT NUM6ER(s) Kenneth R. Hammond, Robert M
The Application of Concurrent Engineering Tools and Design Structure Matrix in Designing Tire
NASA Astrophysics Data System (ADS)
Ginting, Rosnani; Fachrozi Fitra Ramadhan, T.
2016-02-01
The development of automobile industry in Indonesia is growing rapidly. This phenomenon causes companies related to the automobile industry such as tire industry must develop products based on customers’ needs and considering the timeliness of delivering the product to the customer. It could be reached by applying strategic planning in developing an integrated concept of product development. This research was held in PT. XYZ that applied the sequential approach in designing and developing products. The need to improve in one stage of product development could occur re-designing that needs longer time in developing a new product. This research is intended to get an integrated product design concept of tire pertaining to the customer's needs using Concurrent Engineering Tools by implementing the two-phased of product development. The implementation of Concurrent Engineering approach results in applying the stage of project planning, conceptual design, and product modules. The product modules consist of four modules that using Product Architecture - Design Structure Matrix to ease the designing process of new product development.
The design of reversible hydrogels to capture extracellular matrix dynamics
NASA Astrophysics Data System (ADS)
Rosales, Adrianne M.; Anseth, Kristi S.
2016-02-01
The extracellular matrix (ECM) is a dynamic environment that constantly provides physical and chemical cues to embedded cells. Much progress has been made in engineering hydrogels that can mimic the ECM, but hydrogel properties are, in general, static. To recapitulate the dynamic nature of the ECM, many reversible chemistries have been incorporated into hydrogels to regulate cell spreading, biochemical ligand presentation and matrix mechanics. For example, emerging trends include the use of molecular photoswitches or biomolecule hybridization to control polymer chain conformation, thereby enabling the modulation of the hydrogel between two states on demand. In addition, many non-covalent, dynamic chemical bonds have found increasing use as hydrogel crosslinkers or tethers for cell signalling molecules. These reversible chemistries will provide greater temporal control of adhered cell behaviour, and they allow for more advanced in vitro models and tissue-engineering scaffolds to direct cell fate.
Design of inner coupling matrix for robustly self-synchronizing networks
NASA Astrophysics Data System (ADS)
Gequn, Liu; Zhiguo, Zhan; Knowles, Gareth
2015-12-01
A self-synchronizing network may undergo change of scale and topology during its functioning, thus adjustment of parameters is necessary to enable the synchronization. The adjustment cost and runtime-break demand a method to maintain continuous operation of the network. To address these issues, this paper presents an analytical method for the design of the inner coupling matrix. The proposed method renders the synchronization robust to change of network scale and topology. It is usual in network models that scale and topology are represented by outer coupling matrix. In this paper we only consider diffusively coupled networks. For these networks, the eigenvalues of the outer coupling matrix are all non-positive. By utilizing this property, the designed inner coupling matrix can cover the entire left half of complex plane within the synchronized region to underlie robustness of synchronization. After elaborating the applicability of several types of synchronization state for a robustly self-synchronizing network, the analytical design method is given for the stable equilibrium point case. Sometimes the Jacobian matrix of the node dynamical equation may lead to an unrealizable complex inner coupling matrix in the method. We then introduce a lemma of matrix transformation to prevent this possibility. Additionally, we investigated the choice of inner coupling matrix to get a desirable self-synchronization speed. The corresponding condition in the design procedure is given to drive the network synchronization faster than convergence of each node. Finally, the article includes examples that show effectiveness and soundness of the method.
NASA Technical Reports Server (NTRS)
Singh, M.
1999-01-01
Ceramic matrix composite (CMC) components are being designed, fabricated, and tested for a number of high temperature, high performance applications in aerospace and ground based systems. The critical need for and the role of reliable and robust databases for the design and manufacturing of ceramic matrix composites are presented. A number of issues related to engineering design, manufacturing technologies, joining, and attachment technologies, are also discussed. Examples of various ongoing activities in the area of composite databases. designing to codes and standards, and design for manufacturing are given.
Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes
NASA Technical Reports Server (NTRS)
Boyle, Robert
2014-01-01
This project demonstrated that higher temperature capabilities of ceramic matrix composites (CMCs) can be used to reduce emissions and improve fuel consumption in gas turbine engines. The work involved closely coupling aerothermal and structural analyses for the first-stage vane of a high-pressure turbine (HPT). These vanes are actively cooled, typically using film cooling. Ceramic materials have structural and thermal properties different from conventional metals used for the first-stage HPT vane. This project identified vane configurations that satisfy CMC structural strength and life constraints while maintaining vane aerodynamic efficiency and reducing vane cooling to improve engine performance and reduce emissions. The project examined modifications to vane internal configurations to achieve the desired objectives. Thermal and pressure stresses are equally important, and both were analyzed using an ANSYS® structural analysis. Three-dimensional fluid and heat transfer analyses were used to determine vane aerodynamic performance and heat load distributions.
Library designs for generic C++ sparse matrix computations of iterative methods
Pozo, R.
1996-12-31
A new library design is presented for generic sparse matrix C++ objects for use in iterative algorithms and preconditioners. This design extends previous work on C++ numerical libraries by providing a framework in which efficient algorithms can be written *independent* of the matrix layout or format. That is, rather than supporting different codes for each (element type) / (matrix format) combination, only one version of the algorithm need be maintained. This not only reduces the effort for library developers, but also simplifies the calling interface seen by library users. Furthermore, the underlying matrix library can be naturally extended to support user-defined objects, such as hierarchical block-structured matrices, or application-specific preconditioners. Utilizing optimized kernels whenever possible, the resulting performance of such framework can be shown to be competitive with optimized Fortran programs.
2013-01-01
An intuitionistic method is proposed to design shadow masks to achieve thickness profile control for evaporation coating processes. The proposed method is based on the concept of the shadow matrix, which is a matrix that contains coefficients that build quantitive relations between shape parameters of masks and shadow quantities of substrate directly. By using the shadow matrix, shape parameters of shadow masks could be derived simply by solving a matrix equation. Verification experiments were performed on a special case where coating materials have different condensation characteristics. By using the designed mask pair with complementary shapes, thickness uniformities of better than 98% are demonstrated for MgF2 (m = 1) and LaF3 (m = 0.5) simultaneously on a 280 mm diameter spherical substrate with the radius curvature of 200 mm. PMID:24227996
Design verification test matrix development for the STME thrust chamber assembly
NASA Technical Reports Server (NTRS)
Dexter, Carol E.; Elam, Sandra K.; Sparks, David L.
1993-01-01
This report presents the results of the test matrix development for design verification at the component level for the National Launch System (NLS) space transportation main engine (STME) thrust chamber assembly (TCA) components including the following: injector, combustion chamber, and nozzle. A systematic approach was used in the development of the minimum recommended TCA matrix resulting in a minimum number of hardware units and a minimum number of hot fire tests.
NASA Technical Reports Server (NTRS)
1974-01-01
A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.
Structural optical design of the complex multi-group zoom systems by means of matrix optics.
Kryszczyński, T; Mikucki, J
2013-08-26
New matrix formulas for structural optical design have been obtained from analysis of derivative of the system matrix in respect to construction parameters and movements of components. Functional parameters of the optical system become elements of the matrix, presenting working conditions of the optical system. Developed methodology of structural design multi-group zoom systems with unlimited number of components and with mechanical-electronic compensation is presented. Any optical system, such as the objective lens, reproduction system, or telescopic system, can be analyzed with this methodology. Kinematics of components pertaining to a full tract of the zoom system is determined for a discrete number of positions. Three examples of the structural design of complex zoom systems with five-components and high zooming ratio are provided.
Gupta-Ostermann, Disha; Hirose, Yoichiro; Odagami, Takenao; Kouji, Hiroyuki; Bajorath, Jürgen
2015-01-01
In a previous Method Article, we have presented the 'Structure-Activity Relationship (SAR) Matrix' (SARM) approach. The SARM methodology is designed to systematically extract structurally related compound series from screening or chemical optimization data and organize these series and associated SAR information in matrices reminiscent of R-group tables. SARM calculations also yield many virtual candidate compounds that form a "chemical space envelope" around related series. To further extend the SARM approach, different methods are developed to predict the activity of virtual compounds. In this follow-up contribution, we describe an activity prediction method that derives conditional probabilities of activity from SARMs and report representative results of first prospective applications of this approach.
Information Architecture for the Web: The IA Matrix Approach to Designing Children's Portals.
ERIC Educational Resources Information Center
Large, Andrew; Beheshti, Jamshid; Cole, Charles
2002-01-01
Presents a matrix that can serve as a tool for designing the information architecture of a Web portal in a logical and systematic manner. Highlights include interfaces; metaphors; navigation; interaction; information retrieval; and an example of a children's Web portal to provide access to museum information. (Author/LRW)
Design Studies for a Multiple Application Thermal Reactor for Irradiation Experiments (MATRIX)
Pope, Michael A.; Gougar, Hans D.; Ryskamp, J. M.
2015-03-01
The Advanced Test Reactor (ATR) is a high power density test reactor specializing in fuel and materials irradiation. For more than 45 years, the ATR has provided irradiations of materials and fuels testing along with radioisotope production. Should unforeseen circumstances lead to the decommissioning of ATR, the U.S. Government would be left without a large-scale materials irradiation capability to meet the needs of its nuclear energy and naval reactor missions. In anticipation of this possibility, work was performed under the Laboratory Directed Research and Development (LDRD) program to investigate test reactor concepts that could satisfy the current missions of the ATR along with an expanded set of secondary missions. A survey was conducted in order to catalogue the anticipated needs of potential customers. Then, concepts were evaluated to fill the role for this reactor, dubbed the Multi-Application Thermal Reactor Irradiation eXperiments (MATRIX). The baseline MATRIX design is expected to be capable of longer cycle lengths than ATR given a particular batch scheme. The volume of test space in In-Pile-Tubes (IPTs) is larger in MATRIX than in ATR with comparable magnitude of neutron flux. Furthermore, MATRIX has more locations of greater volume having high fast neutron flux than ATR. From the analyses performed in this work, it appears that the lead MATRIX design can be designed to meet the anticipated needs of the ATR replacement reactor. However, this design is quite immature, and therefore any requirements currently met must be re-evaluated as the design is developed further.
Discriminating effects of heterogeneity and matrix diffusion by alternative tracer designs
Tsang, Y.Y.W.
1995-03-01
Flow and transport calculations are carried out by numerical simulation for different tracer designs: single-well radially diverging/converging (huff-puff), single well radially converging, and two-well injection-withdrawal (doublet) in a 2D fracture zone. The fractured rocks are conceptualized as a dual-continuum: the well-connected fractures forming a heterogeneous continuum for advective transport, and the less permeable matrix forming a second continuum for tracer diffusion. Results show that the huff-puff design can be a good diagnostic test for matrix diffusion. The two-well doublet design averages over a large volume and corrects for the extreme sensitivity to spatial heterogeneities of the single well converging test, but requires prior knowledge of presence or absence of matrix diffusion to give reliable estimate of transport parameters. Results of this study demonstrate that using a suite of different tracer designs is important to reduce the uncertainty in association with solving the inverse problem of tracer test interpretation to characterize transport in fractured rocks.
Chen, Deng-kai; Gu, Rong; Gu, Yu-feng; Yu, Sui-huai
2016-01-01
Consumers' Kansei needs reflect their perception about a product and always consist of a large number of adjectives. Reducing the dimension complexity of these needs to extract primary words not only enables the target product to be explicitly positioned, but also provides a convenient design basis for designers engaging in design work. Accordingly, this study employs a numerical design structure matrix (NDSM) by parameterizing a conventional DSM and integrating genetic algorithms to find optimum Kansei clusters. A four-point scale method is applied to assign link weights of every two Kansei adjectives as values of cells when constructing an NDSM. Genetic algorithms are used to cluster the Kansei NDSM and find optimum clusters. Furthermore, the process of the proposed method is presented. The details of the proposed approach are illustrated using an example of electronic scooter for Kansei needs clustering. The case study reveals that the proposed method is promising for clustering Kansei needs adjectives in product emotional design. PMID:27630709
Yang, Yan-Pu; Chen, Deng-Kai; Gu, Rong; Gu, Yu-Feng; Yu, Sui-Huai
2016-01-01
Consumers' Kansei needs reflect their perception about a product and always consist of a large number of adjectives. Reducing the dimension complexity of these needs to extract primary words not only enables the target product to be explicitly positioned, but also provides a convenient design basis for designers engaging in design work. Accordingly, this study employs a numerical design structure matrix (NDSM) by parameterizing a conventional DSM and integrating genetic algorithms to find optimum Kansei clusters. A four-point scale method is applied to assign link weights of every two Kansei adjectives as values of cells when constructing an NDSM. Genetic algorithms are used to cluster the Kansei NDSM and find optimum clusters. Furthermore, the process of the proposed method is presented. The details of the proposed approach are illustrated using an example of electronic scooter for Kansei needs clustering. The case study reveals that the proposed method is promising for clustering Kansei needs adjectives in product emotional design.
Tosetto, Thaís; Camarotto, João Alberto
2012-01-01
The paper presents a correlation between the parameters of classical TRIZ and variables of analysis of the EWA to construct a matrix of contradictions in ergonomics, with the objective of assisting the designing processes in the Brazilian agricultural sector. Given the representativeness of the sector in the economy, the boundary conditions in which the activities are developed and their impact on the health of workers, this proposal should contribute to the development of adaptable solutions and the promotion of Decent Work.
ERIC Educational Resources Information Center
Shreve, Bradley
2016-01-01
To better realize their goals and overcome the many hurdles they encounter, tribal college leaders established the American Indian Higher Education Consortium (AIHEC) to serve as the "collective voice and unifying spirit" of the tribal college movement. For over four decades, AIHEC has taken the dreams and aspirations of the tribal…
Pankajakshan, Divya; Krishnan, Lissy K
2009-01-01
Tissue-engineered blood vessel substitutes should closely resemble native vessels in terms of structure, composition, mechanical properties, and function. Successful cardiovascular tissue engineering requires optimization of in vitro culture environment that would produce functional constructs. The extracellular matrix (ECM) protein elastin plays an essential role in the cardiovascular system to render elasticity to blood vessel wall, whereas collagen is responsible for providing mechanical strength. The objective of this study was to understand the significance of various ECM components on endothelial cell (EC) growth and tissue generation. We demonstrate that, even though fibrin is a good matrix for EC growth, fibronectin is the crucial component of the fibrin matrix that enhances EC adhesion, spreading, and proliferation. Vascular EC growth factor is known to influence in vitro growth of EC, but, so far, ECM deposition in in vitro culture has not been reported. In this study, it is shown that incorporation of a mixture of hypothalamus-derived angiogenic growth factors with fibrin matrix enhances synthesis and deposition of insoluble elastin and collagen in the matrix, within 10 days of in vitro culture. The results suggest that a carefully engineered fibrin composite matrix may support EC growth, survival, and remodeling of ECM in vitro and impart optimum properties to the construct for resisting the shear stress at the time of implantation.
Design of acoustic metamaterials using the covariance matrix adaptation evolutionary strategy
NASA Astrophysics Data System (ADS)
Huang, Bei; Cheng, Qiang; Song, Gang Yong; Cui, Tie Jun
2017-03-01
Acoustic metamaterials can manipulate sound waves in surprising ways, including the focusing, cloaking, and extraordinary transmitting of sound waves. With the increasing requirements for acoustic metamaterials with extreme parameters, we propose the design of acoustic meta-atoms with a large refraction index using the covariance matrix adaptation evolutionary optimization strategy. To validate the procedure, we propose an optimized metamaterial to construct an acoustic deflection lens. The full-wave simulation results are consistent with the theoretical predictions, showing the efficacy and accuracy of the proposed method, and indicating that the optimization algorithm is a powerful tool for designing meta-atoms with excellent applications.
Gunjal, P. T.; Shinde, M. B.; Gharge, V. S.; Pimple, S. V.; Gurjar, M. K.; Shah, M. N.
2015-01-01
The objective of this present investigation was to develop and formulate floating sustained release matrix tablets of s (-) atenolol, by using different polymer combinations and filler, to optimize by using surface response methodology for different drug release variables and to evaluate the drug release pattern of the optimized product. Floating sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: Hydroxypropyl methylcellulose, sodium bicarbonate as a gas generating agent, polyvinyl pyrrolidone as a binder and lactose monohydrate as filler. The 32 full factorial design was employed to investigate the effect of formulation variables on different properties of tablets applicable to floating lag time, buoyancy time, % drug release in 1 and 6 h (D1 h,D6 h) and time required to 90% drug release (t90%). Significance of result was analyzed using analysis of non variance and P < 0.05 was considered statistically significant. S (-) atenolol floating sustained release matrix tablets followed the Higuchi drug release kinetics that indicates the release of drug follows anomalous (non-Fickian) diffusion mechanism. The developed floating sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet. PMID:26798171
NASA Astrophysics Data System (ADS)
Tarhan, Başak; Ünlü, Kahraman
2005-11-01
Designing environmentally safe and economically feasible landfills can be a challenging task due to complex interactions that need to be taken into account between landfill size, waste and site characteristics. The main focus of this study is, by interfacing the geographic information systems (GIS) with system simulation models (SSM), to develop a methodology and a landfill design component selection matrix that can enable the determination of landfill design components providing the desired performance with minimal design details. In this paper, the conceptual framework and applications of the developed methodology demonstrating the selection of landfill design components that are suitable for the existing site conditions are presented. The conceptual model defines design variables, performance criteria and design components of a landfill. GIS and SSM are used to handle the site-specific data and to evaluate the landfill performance, respectively. Results indicate that the landfills having the same design characteristics show different performance under different site conditions; therefore, a landfill design that is technically and economically feasible should be selected on the basis of performance.
A modified Finite Element-Transfer Matrix for control design of space structures
NASA Technical Reports Server (NTRS)
Tan, T.-M.; Yousuff, A.; Bahar, L. Y.; Konstandinidis, M.
1990-01-01
The Finite Element-Transfer Matrix (FETM) method was developed for reducing the computational efforts involved in structural analysis. While being widely used by structural analysts, this method does, however, have certain limitations, particularly when used for the control design of large flexible structures. In this paper, a new formulation based on the FETM method is presented. The new method effectively overcomes the limitations in the original FETM method, and also allows an easy construction of reduced models that are tailored for the control design. Other advantages of this new method include the ability to extract open loop frequencies and mode shapes with less computation, and simplification of the design procedures for output feedback, constrained compensation, and decentralized control. The development of this new method and the procedures for generating reduced models using this method are described in detail and the role of the reduced models in control design is discussed through an illustrative example.
Design of electronic medical record user interfaces: a matrix-based method for improving usability.
Kuqi, Kushtrim; Eveleigh, Tim; Holzer, Thomas; Sarkani, Shahryar; Levin, James E; Crowley, Rebecca S
2013-01-01
This study examines a new approach of using the Design Structure Matrix (DSM) modeling technique to improve the design of Electronic Medical Record (EMR) user interfaces. The usability of an EMR medication dosage calculator used for placing orders in an academic hospital setting was investigated. The proposed method captures and analyzes the interactions between user interface elements of the EMR system and groups elements based on information exchange, spatial adjacency, and similarity to improve screen density and time-on-task. Medication dose adjustment task time was recorded for the existing and new designs using a cognitive simulation model that predicts user performance. We estimate that the design improvement could reduce time-on-task by saving an average of 21 hours of hospital physicians' time over the course of a month. The study suggests that the application of DSM can improve the usability of an EMR user interface.
Optical design and implementation of a variable-pitch dot matrix writer
NASA Astrophysics Data System (ADS)
Lee, Chih-Kung; Hsieh, Chi-Tang J.; Wu, Jeremy W.; Lee, Julie T.
1999-03-01
The fundamental thinking and the optical implementation of an innovative dot matrix writer that can generate image grating pixels of arbitrary grating pitch and grating orientations on a photoresist plate is presented. In this newly developed system, the incident laser beam is split by a beamsplitter to become two incident laser beams. The two coherent light beams are then focused onto a photoresist plate by an especially designed focusing lens. The grating pitch of the grating pixel formed on the photoresist plate can be varied on-the-fly by translating a set of stages to change the distance of the two coherent light beams before impinging on the focusing lens. Moving a lens on the incident light path to change the convergent angle of the incident light beams can change the spot size of this system. As the grating pixels generated by this dot matrix writer are able to have spot sizes, grating orientation, and grating pitch completely specified by the designer, the image effect by this type of dot matrix writer can exert a pre-specified color at each specific viewing angle. Diffractive images with various visual effects and applications that can be created by using this newly invented system are examined.
Strömberg, Eric A; Nyberg, Joakim; Hooker, Andrew C
2016-12-01
With the increasing popularity of optimal design in drug development it is important to understand how the approximations and implementations of the Fisher information matrix (FIM) affect the resulting optimal designs. The aim of this work was to investigate the impact on design performance when using two common approximations to the population model and the full or block-diagonal FIM implementations for optimization of sampling points. Sampling schedules for two example experiments based on population models were optimized using the FO and FOCE approximations and the full and block-diagonal FIM implementations. The number of support points was compared between the designs for each example experiment. The performance of these designs based on simulation/estimations was investigated by computing bias of the parameters as well as through the use of an empirical D-criterion confidence interval. Simulations were performed when the design was computed with the true parameter values as well as with misspecified parameter values. The FOCE approximation and the Full FIM implementation yielded designs with more support points and less clustering of sample points than designs optimized with the FO approximation and the block-diagonal implementation. The D-criterion confidence intervals showed no performance differences between the full and block diagonal FIM optimal designs when assuming true parameter values. However, the FO approximated block-reduced FIM designs had higher bias than the other designs. When assuming parameter misspecification in the design evaluation, the FO Full FIM optimal design was superior to the FO block-diagonal FIM design in both of the examples.
Klapp, Iftach; Mendlovic, David
2009-07-06
The problem of image restoration of space variant blur is common and important. One of the most useful descriptions of this problem is in its algebraic form I=H*O, where O is the object represented as a column vector, I is the blur image represented as a column vector and H is the PSF matrix that represents the optical system. When inverting the problem to restore the geometric object from the blurred image and the known system matrix, restoration is limited in speed and quality by the system condition. Current optical design methods focus on image quality, therefore if additional image processing is needed the matrix condition is taken "as is". In this paper we would like to present a new optical approach which aims to improve the system condition by proper optical design. In this new method we use Singular Value Decomposition (SVD) to define the weak parts of the matrix condition. We design a second optical system based on those weak SVD parts and then we add the second system parallel to the first one. The original and second systems together work as an improved parallel optics system. Following that, we present a method for designing such a "parallel filter" for systems with a spread SVD pattern. Finally we present a study case in which by using our new method we improve a space variant image system with an initial condition number of 8.76e4, down to a condition number of 2.29e3. We use matrix inversion to simulate image restoration. Results show that the new parallel optics immunity to Additive White Gaussian Noise (AWGN) is much better then that of the original simple lens. Comparing the original and the parallel optics systems, the parallel optics system crosses the MSEIF=0 [db] limit in SNR value which is more than 50db lower then the SNR value in the case of the original simple lens. The new parallel optics system performance is also compared to another method based on the MTF approach.
Design and development of high frequency matrix phased-array ultrasonic probes
NASA Astrophysics Data System (ADS)
Na, Jeong K.; Spencer, Roger L.
2012-05-01
High frequency matrix phased-array (MPA) probes have been designed and developed for more accurate and repeatable assessment of weld conditions of thin sheet metals commonly used in the auto industry. Unlike the line focused ultrasonic beam generated by a linear phased-array (LPA) probe, a MPA probe can form a circular shaped focused beam in addition to the typical beam steering capabilities of phased-array probes. A CIVA based modeling and simulation method has been used to design the probes in terms of various probe parameters such as number of elements, element size, overall dimensions, frequency etc. Challenges associated with the thicknesses of thin sheet metals have been resolved by optimizing these probe design parameters. A further improvement made on the design of the MPA probe proved that a three-dimensionally shaped matrix element can provide a better performing probe at a much lower probe manufacturing cost by reducing the total number of elements and lowering the operational frequency. This three dimensional probe naturally matches to the indentation shape of the weld on the thin sheet metals and hence a wider inspection area with the same level of spatial resolution obtained by a twodimensional flat MPA probe operating at a higher frequency. The two aspects, a wider inspection area and a lower probe manufacturing cost, make this three-dimensional MPA sensor more attractive to auto manufacturers demanding a quantitative nondestructive inspection method.
Choi, Du Hyung; Shin, Sangmun; Khoa Viet Truong, Nguyen; Jeong, Seong Hoon
2012-09-01
A robust experimental design method was developed with the well-established response surface methodology and time series modeling to facilitate the formulation development process with magnesium stearate incorporated into hydrophilic matrix tablets. Two directional analyses and a time-oriented model were utilized to optimize the experimental responses. Evaluations of tablet gelation and drug release were conducted with two factors x₁ and x₂: one was a formulation factor (the amount of magnesium stearate) and the other was a processing factor (mixing time), respectively. Moreover, different batch sizes (100 and 500 tablet batches) were also evaluated to investigate an effect of batch size. The selected input control factors were arranged in a mixture simplex lattice design with 13 experimental runs. The obtained optimal settings of magnesium stearate for gelation were 0.46 g, 2.76 min (mixing time) for a 100 tablet batch and 1.54 g, 6.51 min for a 500 tablet batch. The optimal settings for drug release were 0.33 g, 7.99 min for a 100 tablet batch and 1.54 g, 6.51 min for a 500 tablet batch. The exact ratio and mixing time of magnesium stearate could be formulated according to the resulting hydrophilic matrix tablet properties. The newly designed experimental method provided very useful information for characterizing significant factors and hence to obtain optimum formulations allowing for a systematic and reliable experimental design method.
Madgulkar, Ashwini R.; Bhalekar, Mangesh R.; Padalkar, Rahul R.; Shaikh, Mohseen Y.
2013-01-01
The aim was to determine the release-modifying effect of carboxymethyl xyloglucan for oral drug delivery. Sustained release matrix tablets of tramadol HCl were prepared by wet granulation method using carboxymethyl xyloglucan as matrix forming polymer. HPMC K100M was used in a small amount to control the burst effect which is most commonly seen with natural hydrophilic polymers. A simplex centroid design with three independent variables and two dependent variables was employed to systematically optimize drug release profile. Carboxymethyl xyloglucan (X1), HPMC K100M (X2), and dicalcium phosphate (X3) were taken as independent variables. The dependent variables selected were percent of drug release at 2nd hour (Y1) and at 8th hour (Y2). Response surface plots were developed, and optimum formulations were selected on the basis of desirability. The formulated tablets showed anomalous release mechanism and followed matrix drug release kinetics, resulting in regulated and complete release from the tablets within 8 to 10 hours. The polymer carboxymethyl xyloglucan and HPMC K100M had significant effect on drug release from the tablet (P > 0.05). Polynomial mathematical models, generated for various response variables using multiple regression analysis, were found to be statistically significant (P > 0.05). The statistical models developed for optimization were found to be valid. PMID:26555977
Becker, G.K.
1996-09-01
Regulatory compliance programs associated with the Department of Energy (DOE) Waste Isolation Pilot Plant (WIPP) Transuranic (TRU) Waste Characterization Program (the Program) require the collection of waste characterization data of known quality to support repository performance assessment, permitting, and associated activities. Blind audit samples, referred to as PDP (performance demonstration program) samples, are devices used in the NDA PDP program to acquire waste NDA system performance data per defined measurement routines. As defined under the current NDA PDP Program Plan, a PDP sample consists of a DOT 17C 55-gallon PDP matrix drum configured with insertable radioactive standards, working reference materials (WRMs). The particular manner in which the matrix drum and PDP standard(s) are combined is a function of the waste NDA system performance test objectives of a given cycle. The scope of this document is confined to the design of the PDP drum radioactive standard internal support structure, the matrix type and the as installed configuration. The term benign is used to designate a matrix possessing properties which are nominally non-interfering to waste NDA measurement techniques. Measurement interference sources are technique specific but include attributes such as: high matrix density, heterogeneous matrix distributions, matrix compositions containing high moderator/high Z element concentrations, etc. To the extent practicable the matrix drum design should not unduly bias one NDA modality over another due to the manner in which the matrix drum configuration manifests itself to the measurement system. To this end the PDP matrix drum configuration and composition detailed below is driven primarily by the intent to minimize the incorporation of matrix attributes known to interfere with fundamental waste NDA modalities, i.e. neutron and gamma based techniques.
NASA Technical Reports Server (NTRS)
Hanks, Brantley R.; Skelton, Robert E.
1991-01-01
Vibration in modern structural and mechanical systems can be reduced in amplitude by increasing stiffness, redistributing stiffness and mass, and/or adding damping if design techniques are available to do so. Linear Quadratic Regulator (LQR) theory in modern multivariable control design, attacks the general dissipative elastic system design problem in a global formulation. The optimal design, however, allows electronic connections and phase relations which are not physically practical or possible in passive structural-mechanical devices. The restriction of LQR solutions (to the Algebraic Riccati Equation) to design spaces which can be implemented as passive structural members and/or dampers is addressed. A general closed-form solution to the optimal free-decay control problem is presented which is tailored for structural-mechanical system. The solution includes, as subsets, special cases such as the Rayleigh Dissipation Function and total energy. Weighting matrix selection is a constrained choice among several parameters to obtain desired physical relationships. The closed-form solution is also applicable to active control design for systems where perfect, collocated actuator-sensor pairs exist.
NASA Technical Reports Server (NTRS)
Pak, Chan-gi; Li, Wesley W.
2009-01-01
Supporting the Aeronautics Research Mission Directorate guidelines, the National Aeronautics and Space Administration [NASA] Dryden Flight Research Center is developing a multidisciplinary design, analysis, and optimization [MDAO] tool. This tool will leverage existing tools and practices, and allow the easy integration and adoption of new state-of-the-art software. Today s modern aircraft designs in transonic speed are a challenging task due to the computation time required for the unsteady aeroelastic analysis using a Computational Fluid Dynamics [CFD] code. Design approaches in this speed regime are mainly based on the manual trial and error. Because of the time required for unsteady CFD computations in time-domain, this will considerably slow down the whole design process. These analyses are usually performed repeatedly to optimize the final design. As a result, there is considerable motivation to be able to perform aeroelastic calculations more quickly and inexpensively. This paper will describe the development of unsteady transonic aeroelastic design methodology for design optimization using reduced modeling method and unsteady aerodynamic approximation. The method requires the unsteady transonic aerodynamics be represented in the frequency or Laplace domain. Dynamically linear assumption is used for creating Aerodynamic Influence Coefficient [AIC] matrices in transonic speed regime. Unsteady CFD computations are needed for the important columns of an AIC matrix which corresponded to the primary modes for the flutter. Order reduction techniques, such as Guyan reduction and improved reduction system, are used to reduce the size of problem transonic flutter can be found by the classic methods, such as Rational function approximation, p-k, p, root-locus etc. Such a methodology could be incorporated into MDAO tool for design optimization at a reasonable computational cost. The proposed technique is verified using the Aerostructures Test Wing 2 actually designed
Snorradóttir, Bergthóra S; Gudnason, Pálmar I; Thorsteinsson, Freygardur; Másson, Már
2011-04-18
Silicone elastomers are commonly used for medical devices and external prosthesis. Recently, there has been growing interest in silicone-based medical devices with enhanced function that release drugs from the elastomer matrix. In the current study, an experimental design approach was used to optimize the release properties of the model drug diclofenac from medical silicone elastomer matrix, including a combination of four permeation enhancers as additives and allowing for constraints in the properties of the material. The D-optimal design included six factors and five responses describing material properties and release of the drug. The first experimental object was screening, to investigate the main and interaction effects, based on 29 experiments. All excipients had a significant effect and were therefore included in the optimization, which also allowed the possible contribution of quadratic terms to the model and was based on 38 experiments. Screening and optimization of release and material properties resulted in the production of two optimized silicone membranes, which were tested for transdermal delivery. The results confirmed the validity of the model for the optimized membranes that were used for further testing for transdermal drug delivery through heat-separated human skin. The optimization resulted in an excipient/drug/silicone composition that resulted in a cured elastomer with good tensile strength and a 4- to 7-fold transdermal delivery increase relative to elastomer that did not contain excipients.
Dormán, György; Cseh, Sándor; Hajdú, István; Barna, László; Kónya, Dénes; Kupai, Krisztina; Kovács, László; Ferdinandy, Péter
2010-05-28
Matrix metalloproteinases (MMPs) play an important role in tissue remodelling associated with various physiological and pathological processes, such as morphogenesis, angiogenesis, tissue repair, arthritis, chronic heart failure, chronic obstructive pulmonary disease, chronic inflammation and cancer metastasis. As a result, MMPs are considered to be viable drug targets in the therapy of these diseases. Despite the high therapeutic potential of MMP inhibitors (MMPIs), all clinical trials have failed to date, except for doxycycline for periodontal disease. This can be attributed to (i) poor selectivity of the MMPIs, (ii) poor target validation for the targeted therapy and (iii) poorly defined predictive preclinical animal models for safety and efficacy. Lessons from previous failures, such as recent discoveries of oxidative/nitrosative activation and phosphorylation of MMPs, as well as novel non-matrix related intra- and extracellular targets of MMP, give new hope for MMPI development for both chronic and acute diseases. In this article we critically review the major structural determinants of the selectivity and the milestones of past design efforts of MMPIs where 2-/3-dimensional structure-based methods were intensively applied. We also analyse the in vitro screening and preclinical/clinical pharmacology approaches, with particular emphasis on drawing conclusions on how to overcome efficacy and safety problems through better target validation and design of preclinical studies.
NASA Astrophysics Data System (ADS)
Theodore, Zachary B.
A robust proportional-integral (PI) controller was synthesized for the F-16 VISTA (Variable stability In-flight Simulator Test Aircraft) using a linear matrix inequality (LMI) approach, with the goal of eventually designing and implementing a linear parameter-varying PI controller on high performance aircraft. The combination of classical and modern control theory provides theoretically guaranteed stability and performance throughout the flight envelope and ease of implementation due to the simplicity of the PI controller structure. The controller is designed by solving a set of LMIs with pole placement constraints. This closed-loop system was simulated in MATLAB/Simulink to analyze the performance of the controller. A robust Hinfinity controller was also developed to compare performance with PI controller. The simulation results showed stability, albeit with poor performance compared to the Hinfinity controlle.
Study of mould design and forming process on advanced polymer-matrix composite complex structure
NASA Astrophysics Data System (ADS)
Li, S. J.; Zhan, L. H.; Bai, H. M.; Chen, X. P.; Zhou, Y. Q.
2015-07-01
Advanced carbon fibre-reinforced polymer-matrix composites are widely applied to aviation manufacturing field due to their outstanding performance. In this paper, the mould design and forming process of the complex composite structure were discussed in detail using the hat stiffened structure as an example. The key issues of the moulddesign were analyzed, and the corresponding solutions were also presented. The crucial control points of the forming process such as the determination of materials and stacking sequence, the temperature and pressure route of the co-curing process were introduced. In order to guarantee the forming quality of the composite hat stiffened structure, a mathematical model about the aperture of rubber mandrel was introduced. The study presented in this paper may provide some actual references for the design and manufacture of the important complex composite structures.
Design, analysis, and testing of a metal matrix composite web/flange intersection
NASA Technical Reports Server (NTRS)
Biggers, S. B.; Knight, N. F., Jr.; Moran, S. G.; Olliffe, R.
1992-01-01
An experimental and analytical program to study the local design details of a typical T-shaped web/flange intersection made from a metal matrix composite is described. Loads creating flange bending were applied to specimens having different designs and boundary conditions. Finite element analyses were conducted on models of the test specimens to predict the structural response. The analyses correctly predict failure load, mode, and location in the fillet material in the intersection region of the web and the flange when specimen quality is good. The test program shows the importance of fabrication quality in the intersection region. The full-scale test program that led to the investigation of this local detail is also described.
Designing and synthesis of a polymer matrix piezoelectric composite for energy harvesting
NASA Astrophysics Data System (ADS)
Biswal, Asutya Kumar; Das, Satyabati; Roy, Amritendu
2017-02-01
Now a day, a large variety of electronic and network devices require small yet steady power supply for operation. Traditionally, these devices are battery operated and the batteries are periodically charged for continuous operation. Often, the devices are so located that supply of power to recharge the batteries becomes challenging. Electrical energy harvesting by means of principle of piezoelectricity could be a viable solution to the above problem by means of providing a permanent power source. In this regard, piezoelectric lead zirconium titanate (PZT) was found to be a potential material. However, poor mechanical properties (brittleness) of bulk ceramic materials have been a concern for energy harvesting by means of mechanical motion (footsteps). In the present work, Pb(Zr 0.52 Ti 0.48)1‑x NbxO 3 at x=0.05 was prepared by conventional solid state synthesis route. XRD and SEM analyses were performed for structural characterization. PZT powders were found to be in single phase with tetragonal symmetry without any trace of a second phase. To render the required mechanical properties (flexibility), in the present work, we designed a polymer matrix ceramic composite without much compromising the piezoelectric properties. We prepared composite thick films of lead zirconium titanate (PZT) ceramic in poly vinylidene fluoride (PVDF) polymer matrix with varied composition of PZT from 10-50 vol %. The study of surface morphology by scanning electron microscope (SEM) shows good degree of dispersion of PZT in PVDF matrix. Ferroelectric characteristics of the composite films were studied by measuring the polarization-electric field hysteresis loops. Generated output voltage and current from the composite films are found to be approximately 0.35 volt and 4 nA, respectively.
Bannwart, Flávio C; Penelet, Guillaume; Lotton, Pierrick; Dalmont, Jean-Pierre
2013-05-01
The successful design of a thermoacoustic engine depends on the appropriate description of the processes involved inside the thermoacoustic core (TAC). This is a difficult task when considering the complexity of both the heat transfer phenomena and the geometry of the porous material wherein the thermoacoustic amplification process occurs. An attempt to getting round this difficulty consists in measuring the TAC transfer matrix under various heating conditions, the measured transfer matrices being exploited afterward into analytical models describing the complete apparatus. In this paper, a method based on impedance measurements is put forward, which allows the accurate measurement of the TAC transfer matrix, contrarily to the classical two-load method. Four different materials are tested, each one playing as the porous element allotted inside the TAC, which is submitted to different temperature gradients to promote thermoacoustic amplification. The experimental results are applied to the modeling of basic standing-wave and traveling-wave engines, allowing the prediction of the engine operating frequency and thermoacoustic amplification gain, as well as the optimum choice of the components surrounding the TAC.
Application of a sparse matrix design strategy to the synthesis of dos libraries.
Akella, Lakshmi B; Marcaurelle, Lisa A
2011-07-11
We have implemented an interactive and practical sparse matrix design strategy for the synthesis of DOS libraries, which facilitates the selection of diverse library members within a user-defined range of physicochemical properties while still maintaining synthetic efficiency. The utility of this approach is illustrated with the synthesis of an 8000-membered library of stereochemically diverse medium-sized rings accessible via a build/couple/pair DOS strategy. Diverse library members were selected from a virtual library by applying the maximum dissimilarity method, while the selection of similar analogs around each diverse product was ensured by picking near neighbors algorithmically based on fingerprint comparison. Adjustable filters on compound properties, which can be tailored to suit the needs of the target biology, facilitated subset selection from the synthetically accessible compounds.
Giustiniano, Mariateresa; Agamennone, Mariangela; Rossello, Armando; Gomez-Monterrey, Isabel; Novellino, Ettore; Campiglia, Pietro; Vernieri, Ermelinda; Bertamino, Alessia; Carotenuto, Alfonso
2013-01-01
A number of matrix metalloproteinases (MMPs) are important medicinal targets for conditions ranging from rheumatoid arthritis to cardiomyopathy, periodontal disease, liver cirrhosis, multiple sclerosis, and cancer invasion and metastasis, where they showed to have a dual role, inhibiting or promoting important processes involved in the pathology. MMPs contain a zinc (II) ion in the protein active site. Small-molecule inhibitors of these metalloproteins are designed to bind directly to the active site metal ions. In an effort to devise new approaches to selective inhibitors, in this paper, we describe the synthesis and preliminary biological evaluation of amino acid derivatives as new zinc binding groups (ZBGs). The incorporation of selected metal-binding functions in more complex biphenyl sulfonamide moieties allowed the identification of one compound able to interact selectively with different MMP enzymatic isoforms. PMID:23555050
Ogungbenro, Kayode; Aarons, Leon
2011-08-01
In the recent years, interest in the application of experimental design theory to population pharmacokinetic (PK) and pharmacodynamic (PD) experiments has increased. The aim is to improve the efficiency and the precision with which parameters are estimated during data analysis and sometimes to increase the power and reduce the sample size required for hypothesis testing. The population Fisher information matrix (PFIM) has been described for uniresponse and multiresponse population PK experiments for design evaluation and optimisation. Despite these developments and availability of tools for optimal design of population PK and PD experiments much of the effort has been focused on repeated continuous variable measurements with less work being done on repeated discrete type measurements. Discrete data arise mainly in PDs e.g. ordinal, nominal, dichotomous or count measurements. This paper implements expressions for the PFIM for repeated ordinal, dichotomous and count measurements based on analysis by a mixed-effects modelling technique. Three simulation studies were used to investigate the performance of the expressions. Example 1 is based on repeated dichotomous measurements, Example 2 is based on repeated count measurements and Example 3 is based on repeated ordinal measurements. Data simulated in MATLAB were analysed using NONMEM (Laplace method) and the glmmML package in R (Laplace and adaptive Gauss-Hermite quadrature methods). The results obtained for Examples 1 and 2 showed good agreement between the relative standard errors obtained using the PFIM and simulations. The results obtained for Example 3 showed the importance of sampling at the most informative time points. Implementation of these expressions will provide the opportunity for efficient design of population PD experiments that involve discrete type data through design evaluation and optimisation.
PID controller design for output PDFs of stochastic systems using linear matrix inequalities.
Guo, Lei; Wang, Hong
2005-02-01
This paper presents a pseudo proportional-integral-derivative (PID) tracking control strategy for general non-Gaussian stochastic systems based on a linear B-spline model for the output probability density functions (PDFs). The objective is to control the conditional PDFs of the system output to follow a given target function. Different from existing methods, the control structure (i.e., the PID) is imposed before the output PDF controller design. Following the linear B-spline approximation on the measured output PDFs, the concerned problem is transferred into the tracking of given weights which correspond to the desired PDF. For systems with or without model uncertainties, it is shown that the solvability can be casted into a group of matrix inequalities. Furthermore, an improved controller design procedure based on the convex optimization is proposed which can guarantee the required tracking convergence with an enhanced robustness. Simulations are given to demonstrate the efficiency of the proposed approach and encouraging results have been obtained.
Kabir, Khairul; Haidar, Azzam; Tomov, Stanimire; Dongarra, Jack J
2015-01-01
The manycore paradigm shift, and the resulting change in modern computer architectures, has made the development of optimal numerical routines extremely challenging. In this work, we target the development of numerical algorithms and implementations for Xeon Phi coprocessor architecture designs. In particular, we examine and optimize the general and symmetric matrix-vector multiplication routines (gemv/symv), which are some of the most heavily used linear algebra kernels in many important engineering and physics applications. We describe a successful approach on how to address the challenges for this problem, starting with our algorithm design, performance analysis and programing model and moving to kernel optimization. Our goal, by targeting low-level and easy to understand fundamental kernels, is to develop new optimization strategies that can be effective elsewhere for use on manycore coprocessors, and to show significant performance improvements compared to existing state-of-the-art implementations. Therefore, in addition to the new optimization strategies, analysis, and optimal performance results, we finally present the significance of using these routines/strategies to accelerate higher-level numerical algorithms for the eigenvalue problem (EVP) and the singular value decomposition (SVD) that by themselves are foundational for many important applications.
Rao, B Govinda
2005-01-01
It has been 10 years since a 3-dimensional structure of the catalytic domain of a Matrix Metalloprotease (MMP) was revealed for the first time in 1994. More than 80 structures of different MMPs in apo and inhibited forms, determined by X-ray crystallography and NMR methods, have been published by the end of year 2003. A large number of very potent inhibitors have been disclosed in published and patent literature. Several MMP inhibitors entered clinical trials for the treatment of cancer and arthritis. Most of the first generation inhibitors have hydroxamic acid as the Zinc-binding group and have limited specificity. With the failure of these inhibitors in clinical trials, more efforts have been directed to the design of specific inhibitors with different Zn-binding groups in recent years. This review will summarize all the published structural information and focus on the inhibitors that were designed to take advantage of the nonprime side of the MMP active site using structural information and computational analysis. Representative structures from all MMPs are aligned to a target structure to provide a better understanding of the similarities and differences of the active site pockets. This analysis supports the view that the differences in the nonprime side pockets provide better opportunities for designing inhibitors with higher specificity. Published information on all the Zinc-binding groups of MMP inhibitors is reviewed for the first time. Pros and cons of inhibitors with non-hydroxamate Zinc-binding groups in terms of specificity, toxicity and pharmacokinetic properties are discussed.
Cloete, Kevin Wesley; Ristow, Peter Gustav; Kasu, Mohaimin; D'Amato, Maria Eugenia
2017-03-01
CE equipment detects and deconvolutes mixtures containing up to six fluorescently labeled DNA fragments. This deconvolution is done by the collection software that requires a spectral calibration file. The calibration file is used to adjust for the overlap that occurs between the emission spectra of fluorescence dyes. All commercial genotyping and sequencing kits require the installation of a corresponding matrix standard to generate a calibration file. Due to the differences in emission spectrum overlap between fluorescent dyes, the application of existing commercial matrix standards to the electrophoretic separation of DNA labeled with other fluorescent dyes can yield undesirable results. Currently, the number of fluorescent dyes available for oligonucleotide labeling surpasses the availability of commercial matrix standards. Therefore, in this study we developed and evaluated a customized matrix standard using ATTO 633, ATTO 565, ATTO 550, ATTO Rho6G, and 6-FAM dyes for which no commercial matrix standard is available. We highlighted the potential genotyping errors of using an incorrect matrix standard by evaluating the relative performance of our custom dye set using six matrix standards. The specific performance of two genotyping kits (UniQTyper™ Y-10 version 1.0 and PowerPlex® Y23 System) was also evaluated using their specific matrix standards. The procedure we followed for the construction of our custom dye matrix standard can be extended to other fluorescent dyes.
T, Veenus Seelan; Henry, Linda Jeeva Kumari; Narra, Kishore; Lalduhsanga, Pachuau; Kandasamy, Ruckmani
2016-11-01
The present study deals with the development of natural macromolecule gum Albizia stipulata (AS) based novel pharmaceutical excipient for the controlled-release of paracetamol (PC). Central composite design (CCD) two-factor, five-level was used for the optimization of independent variables AS gum and compression force (CF) based on desired response variable drug release (DR) of paracetamol matrix tablets (PCMT). The optimized PCMT was prepared by wet granulation method and screened for pre- and post- compression parameters, and were characterized. The optimized PCMT (F14) formulation showed favorable in vitro release of PC (65%) in 12h, and the release kinetics followed zero order anomalous diffusion mechanism. AS gum exerted significant (p<0.001) anticancer activity with 98.25% inhibition at 2000μg/mL (IC50=179.12μg/mL) against A549 cell line. PC and PCMT showed 78.56% inhibition (IC50 value=856.58μg/mL) and 93.68% inhibition (IC50 value=396.35μg/mL) respectively, symbolizing that the gum remarkably potentiated the anticancer effect of PC in formulation after 24h treatment by inducing apoptosis. This is the first report on A. stipulata gum as a promising biopolymer for drug delivery application in cancer therapeutics.
Design Considerations for Ceramic Matrix Composite Vanes for High Pressure Turbine Applications
NASA Technical Reports Server (NTRS)
Boyle, Robert J.; Parikh, Ankur H.; Nagpal, Vinod K.; Halbig, Michael C.
2013-01-01
Issues associated with replacing conventional metallic vanes with Ceramic Matrix Composite (CMC) vanes in the first stage of the High Pressure Turbine (HPT) are explored. CMC materials have higher temperature capability than conventional HPT vanes, and less vane cooling is required. The benefits of less vane coolant are less NOx production and improved vane efficiency. Comparisons between CMC and metal vanes are made at current rotor inlet temperatures and at an vane inlet pressure of 50 atm.. CMC materials have directionally dependent strength characteristics, and vane designs must accommodate these characteristics. The benefits of reduced NOx and improved cycle efficiency obtainable from using CMC vanes. are quantified Results are given for vane shapes made of a two dimensional CMC weave. Stress components due to thermal and pressure loads are shown for all configurations. The effects on stresses of: (1) a rib connecting vane pressure and suction surfaces; (2) variation in wall thickness; and (3) trailing edge region cooling options are discussed. The approach used to obtain vane temperature distributions is discussed. Film cooling and trailing edge ejection were required to avoid excessive vane material temperature gradients. Stresses due to temperature gradients are sometimes compressive in regions where pressure loads result in high tensile stresses.
Sultana, Afrin; Reznik, Alla; Karim, Karim S; Rowlands, J A
2008-10-01
Protein crystallography is the most important technique for resolving the three-dimensional atomic structure of protein by measuring the intensity of its x-ray diffraction pattern. This work proposes a large area flat panel detector for protein crystallography based on direct conversion x-ray detection technique using avalanche amorphous selenium (a-Se) as the high gain photoconductor, and active matrix readout using amorphous silicon (a-Si:H) thin film transistors. The detector employs avalanche multiplication phenomenon of a-Se to make the detector sensitive to each incident x ray. The advantages of the proposed detector over the existing imaging plate and charge coupled device detectors are large area, high dynamic range coupled to single x-ray detection capability, fast readout, high spatial resolution, and inexpensive manufacturing process. The optimal detector design parameters (such as detector size, pixel size, and thickness of a-Se layer), and operating parameters (such as electric field across the a-Se layer) are determined based on the requirements for protein crystallography application. The performance of the detector is evaluated in terms of readout time (<1 s), dynamic range (approximately 10(5)), and sensitivity (approximately 1 x-ray photon), thus validating the detector's efficacy for protein crystallography.
SURVEY DESIGN FOR SPECTRAL ENERGY DISTRIBUTION FITTING: A FISHER MATRIX APPROACH
Acquaviva, Viviana; Gawiser, Eric; Bickerton, Steven J.; Grogin, Norman A.; Guo Yicheng; Lee, Seong-Kook
2012-04-10
The spectral energy distribution (SED) of a galaxy contains information on the galaxy's physical properties, and multi-wavelength observations are needed in order to measure these properties via SED fitting. In planning these surveys, optimization of the resources is essential. The Fisher Matrix (FM) formalism can be used to quickly determine the best possible experimental setup to achieve the desired constraints on the SED-fitting parameters. However, because it relies on the assumption of a Gaussian likelihood function, it is in general less accurate than other slower techniques that reconstruct the probability distribution function (PDF) from the direct comparison between models and data. We compare the uncertainties on SED-fitting parameters predicted by the FM to the ones obtained using the more thorough PDF-fitting techniques. We use both simulated spectra and real data, and consider a large variety of target galaxies differing in redshift, mass, age, star formation history, dust content, and wavelength coverage. We find that the uncertainties reported by the two methods agree within a factor of two in the vast majority ({approx}90%) of cases. If the age determination is uncertain, the top-hat prior in age used in PDF fitting to prevent each galaxy from being older than the universe needs to be incorporated in the FM, at least approximately, before the two methods can be properly compared. We conclude that the FM is a useful tool for astronomical survey design.
NASA Technical Reports Server (NTRS)
Packard, A. K.; Sastry, S. S.
1986-01-01
A method of solving a class of linear matrix equations over various rings is proposed, using results from linear geometric control theory. An algorithm, successfully implemented, is presented, along with non-trivial numerical examples. Applications of the method to the algebraic control system design methodology are discussed.
NASA Astrophysics Data System (ADS)
Azizur Rahman, M.; Fujimura, Hiroyuki; Shinjo, Ryuichi; Oomori, Tamotsu
2011-06-01
In this study, we demonstrate a key function of extracellular matrix proteins (ECMPs) on seed crystals, which are isolated from calcified endoskeletons of soft coral and contain only CaCO 3 without any living cells. This is the first report that an ECMP protein extracted from a marine organism could potentially influence in modifying the surface of a substrate for designing materials via crystallization. We previously studied with the ECMPs from a different type of soft coral ( Sinularia polydactyla) without introducing any seed crystals in the process , which showed different results. Thus, crystallization on the seed in the presence of ECMPs of present species is an important first step toward linking function to individual proteins from soft coral. For understanding this interesting phenomenon, in vitro crystallization was initiated in a supersaturated solution on seed particles of calcite (1 0 4) with and without ECMPs. No change in the crystal growth shape occurred without ECMPs present during the crystallization process. However, with ECMPs, the morphology and phase of the crystals in the crystallization process changed dramatically. Upon completion of crystallization with ECMPs, an attractive crystal morphology was found. Scanning electron microscopy (SEM) was utilized to observe the crystal morphologies on the seeds surface. The mineral phases of crystals nucleated by ECMPs on the seeds surface were examined by Raman spectroscopy. Although 50 mM Mg 2+ is influential in making aragonite in the crystallization process, the ECMPs significantly made calcite crystals even when 50 mM Mg 2+ was present in the process. Crystallization with the ECMP additive seems to be a technically attractive strategy to generate assembled micro crystals that could be used in crystals growth and design in the Pharmaceutical and biotechnology industries.
Digital-coded matrix system simplifies design and construction of flow charts
NASA Technical Reports Server (NTRS)
Otoole, E.
1971-01-01
Matrix system utilizing unique digital code enables drawing block diagrams with parallel blocks. Complete freedom is obtained in laying out diagram, and it is possible to go directly from matrix to finished drawing. Need to rough out diagram is eliminated and time involved is greatly reduced.
Saurí, J; Millán, D; Suñé-Negre, J M; Colom, H; Ticó, J R; Miñarro, M; Pérez-Lozano, P; García-Montoya, E
2014-12-30
The aim of this study is to obtain swelling controlled release matrix tablets of captopril using the Quality by Design methodology (ICH Q8) and to know the transport mechanisms involved in captopril release. To obtain the area of knowledge, the design of experiments studying the effect of two components (HPMC K15M and ethylcellulose) at different levels has been applied, with the captopril dissolution profile as the product's most important critical quality attribute (CQA). Different dissolution profiles have been obtained with the design of experiments performed, which is a key factor in the development of controlled release matrix tablets. Kinetic analysis according to the equations of Higuchi and Korsmeyer-Peppas demonstrates that the release mechanism is a mechanism of erosion when the whole percentage of the polymer is ethylcellulose, and a diffusion mechanism when the whole percentage of the polymer is HPMC K15M. The physico-chemical characteristics of the gel layer determine the release rate of captopril. The thickness of the gel layer, the porosity which is formed in the matrix upon contact with water, pore size, the swelling rate, the erosion rate of the matrix, and the physico-chemical characteristics of captopril, are factors related to the kinetic equations described and that allow us to predict the release mechanism of captopril. A new relationship of the kinetic equations governing the in vitro behavior with the physical characteristics of the gel layer of the different formulations has been established. This study shows that the size of water-filled pores and the degree of crosslinking between the chains of HPMC K15M of the matrix are related to the exponent n of the Korsmeyer-Peppas equation and the type of transport of the captopril from within the matrix to the dissolution medium, that is, if the transport is only through water-filled pores, or if a combination of diffusion occurs through water-filled pores with a transport through continuous
NASA Astrophysics Data System (ADS)
Deng, Meng
The first part of the work presented in this dissertation is focused on the design and development of novel miscible and biocompatible polyphosphazene-polyester blends as candidate materials for scaffold-based bone tissue engineering applications. Biodegradable polyesters such as poly(lactide-co-glycolide) (PLAGA) are among the most widely used polymeric materials for bone tissue engineering. However, acidic degradation products resulting from the bulk degradation mechanism often lead to catastrophic failure of the structure integrity, and adversely affect biocompatibility both in vitro and in vivo. One promising approach to circumvent these limitations is to blend PLAGA with other macromolecules that can buffer the acidic degradation products with a controlled degradation rate. Biodegradable polyphosphazenes (PPHOS), a new class of biomedical materials, have proved to be superior candidate materials to achieve this objective due to their unique buffering degradation products. A highly practical blending approach was adopted to develop novel biocompatible, miscible blends of these two polymers. In order to achieve this miscibility, a series of amino acid ester, alkoxy, aryloxy, and dipeptide substituted PPHOS were synthesized to promote hydrogen bonding interactions with PLAGA. Five mixed-substituent PPHOS compositions were designed and blended with PLAGA at different weight ratios producing candidate blends via a mutual solvent method. Preliminary characterization identified two specific side groups namely glycylglycine dipeptide and phenylphenoxy that resulted in improved blend miscibility and enhanced in vitro osteocompatibility. These findings led to the synthesis of a mixed-substituent polyphosphazene poly[(glycine ethyl glycinato)1(phenylphenoxy)1phosphazene] (PNGEGPhPh) for blending with PLAGA. Two dipeptide-based blends having weight ratios of PNGEGPhPh to PLAGA namely 25:75 (Matrix1) and 50:50 (Matrix2) were fabricated. Both of the blends were
NASA Astrophysics Data System (ADS)
Wu, Su-Yong; Long, Xing-Wu; Yang, Kai-Yong
2009-09-01
To improve the current status of home multilayer optical coating design with low speed and poor efficiency when a large layer number occurs, the accurate calculation and fast realization of merit function’s gradient and Hesse matrix is pointed out. Based on the matrix method to calculate the spectral properties of multilayer optical coating, an analytic model is established theoretically. And the corresponding accurate and fast computation is successfully achieved by programming with Matlab. Theoretical and simulated results indicate that this model is mathematically strict and accurate, and its maximal precision can reach floating-point operations in the computer, with short time and fast speed. Thus it is very suitable to improve the optimal search speed and efficiency of local optimization methods based on the derivatives of merit function. It has outstanding performance in multilayer optical coating design with a large layer number.
NASA Astrophysics Data System (ADS)
Greer, James A.
2011-11-01
Since the development of the Matrix Assisted Pulsed Laser Evaporation (MAPLE) process by the Naval Research Laboratory (NRL) in the late 1990s, MAPLE has become an active area of research for the deposition of a variety of polymer, biological, and organic thin films. As is often the case with advancements in thin-film deposition techniques new technology sometimes evolves by making minor or major adjustments to existing deposition process equipment and techniques. This is usually the quickest and least expensive way to try out new ideas and to "push the envelope" in order to obtain new and unique scientific results as quickly as possible. This process of "tweaking" current equipment usually works to some degree, but once the new process is further refined overall designs for a new deposition tool based on the critical attributes of the new process typically help capitalize more fully on the all the salient features of the new and improved process. This certainly has been true for the MAPLE process. In fact the first MAPLE experiments the polymer/solvent matrix was mixed and poured into a copper holder held at LN2 temperature on a laboratory counter top. The holder was then quickly placed onto a LN2 cooled reservoir in a vacuum deposition chamber and placed in a vertical position on a LN2 cooled stage and pumped down as quickly as possible. If the sample was not placed into the chamber quickly enough the frozen matrix would melt and drip into the bottom of the chamber onto the chambers main gate valve making a bit of a mess. However, skilled and motivated scientists usually worked quickly enough to make this process work most of the time. The initial results from these experiments were encouraging and led to several publications which sparked considerable interest in this newly developed technique Clearly this approach provided the vision that MAPLE was a viable deposition process, but the equipment was not optimal for conducting MAPLE experiments on a regular basis
Optimal binning of X-ray spectra and response matrix design
NASA Astrophysics Data System (ADS)
Kaastra, J. S.; Bleeker, J. A. M.
2016-03-01
Aims: A theoretical framework is developed to estimate the optimal binning of X-ray spectra. Methods: We derived expressions for the optimal bin size for model spectra as well as for observed data using different levels of sophistication. Results: It is shown that by taking into account both the number of photons in a given spectral model bin and their average energy over the bin size, the number of model energy bins and the size of the response matrix can be reduced by a factor of 10-100. The response matrix should then contain the response at the bin centre as well as its derivative with respect to the incoming photon energy. We provide practical guidelines for how to construct optimal energy grids as well as how to structure the response matrix. A few examples are presented to illustrate the present methods.
Performance and Safety Tests of Lithium-Ion Cells Arranged in a Matrix Design Configuration
NASA Technical Reports Server (NTRS)
Jeevarajan, Judith; Tracinski, Walt
2010-01-01
Matrix Packs display large variations in cell bank voltages at the charge and discharge current (C/2) used in this test program. The voltage difference is larger at the end of discharge than at the end of charge under the conditions studied. Disconnection of a cell from the pack leads to a larger voltage difference during discharge (greater than 2.0 V) between the bank that has one less cell and the other banks. Thermal profile does not show any significant changes or increase in temperature after one cell was disconnected from the bank in spite of falling to very low voltages at the end of discharge. All tests on the matrix pack with the HAM displayed lower max in general due to the placement of thermocouple on the outside of the HAM rather than on the cells. Disconnection of cells has almost no influence on the performance of the packs and does not show any abnormal thermal changes for the 100 cycles obtained in this test program. Longer cycle life may influence the performance especially if the low voltage cell goes into reversal. Overcharge leads to CID activation of cells. If the matrix configuration has a larger number of cells in series, (more than 5 S configuration), the limitations of protective devices may manifest itself irrespective of it being in a matrix configuration. External short circuit causes a fire with expulsion of content from some cells. The fire does not propagate itself laterally, but if there was cell module stacking, then the fire would cause the cells above it to also go into flames/thermal runaway. Limitations of protective devices are observed in this case as the PTCs in the cells did not protect under this abusive condition. Matrix configurations seem to provide protection against lateral propagation of fire and flame. Matrix pack configuration seems to provide good performance in spite of losing cell connections; at least for the configuration tested under this program.
Duncan, Neil A; Bruehlmann, Sabina B; Hunter, Christopher J; Shao, Xinxin; Kelly, Elizabeth J
2014-01-01
Designing biomaterials to mimic and function within the complex mechanobiological conditions of connective tissues requires a detailed understanding of the micromechanical environment of the cell. The objective of our study was to measure the in situ cell-matrix strains from applied tension in both tendon fascicles and cell-seeded type I collagen scaffolds using laser scanning confocal microscopy techniques. Tendon fascicles and collagen gels were fluorescently labelled to simultaneously visualise the extracellular matrix and cell nuclei under applied tensile strains of 5%. There were significant differences observed in the micromechanics at the cell-matrix scale suggesting that the type I collagen scaffold did not replicate the pattern of native tendon strains. In particular, although the overall in situ tensile strains in the matrix were quite similar (∼2.5%) between the tendon fascicles and the collagen scaffolds, there were significant differences at the cell-matrix boundary with visible shear across cell nuclei of >1 μm measured in native tendon which was not observed at all in the collagen scaffolds. Similarly, there was significant non-uniformity of intercellular strains with relative sliding observed between cell rows in tendon which again was not observed in the collagen scaffolds where the strain environment was much more uniform. If the native micromechanical environment is not replicated in biomaterial scaffolds, then the cells may receive incorrect or mixed mechanical signals which could affect their biosynthetic response to mechanical load in tissue engineering applications. This study highlights the importance of considering the microscale mechanics in the design of biomaterial scaffolds and the need to incorporate such features in computational models of connective tissues.
Designing a good life: a matrix for the technological mediation of morality.
Swierstra, Tsjalling; Waelbers, Katinka
2012-03-01
Technologies fulfill a social role in the sense that they influence the moral actions of people, often in unintended and unforeseen ways. Scientists and engineers are already accepting much responsibility for the technological, economical and environmental aspects of their work. This article asks them to take an extra step, and now also consider the social role of their products. The aim is to enable engineers to take a prospective responsibility for the future social roles of their technologies by providing them with a matrix that helps to explore in advance how emerging technologies might plausibly affect the reasons behind people's (moral) actions. On the horizontal axis of the matrix, we distinguished the three basic types of reasons that play a role in practical judgment: what is the case, what can be done and what should be done. On the vertical axis we distinguished the morally relevant classes of issues: stakeholders, consequences and the good life. To illustrate how this matrix may work in practice, the final section applies the matrix to the case of the Google PowerMeter.
NASA Astrophysics Data System (ADS)
Souza, Luiz C. G.; Bigot, P.
2016-10-01
One of the most well-known techniques of optimal control is the theory of Linear Quadratic Regulator (LQR). This method was originally applied only to linear systems but has been generalized for non-linear systems: the State Dependent Riccati Equation (SDRE) technique. One of the advantages of SDRE is that the weight matrix selection is the same as in LQR. The difference is that weights are not necessarily constant: they can be state dependent. Then, it gives an additional flexibility to design the control law. Many are applications of SDRE for simulation or real time control but generally SDRE weights are chosen constant so no advantage of this flexibility is taken. This work serves to show through simulation that state dependent weights matrix can improve SDRE control performance. The system is a non-linear flexible rotatory beam. In a brief first part SDRE theory will be explained and the non-linear model detailed. Then, influence of SDRE weight matrix associated with the state Q will be analyzed to get some insight in order to assume a state dependent law. Finally, these laws are tested and compared to constant weight matrix Q. Based on simulation results; one concludes showing the benefits of using an adaptive weight Q rather than a constant one.
1985-09-01
SUB. R Flat-Panel Dot-Matrix Displays, Color, Alphanumeric, 23 07 Video, LED, Grey Scale, Luminance, Optical Coupling, 23 11 Contrast, Legibility...based flight simulations and bench test experiments. SPECIFICS Method Utilizing the bottom-up methodology, the electro- optical % characteristics and...switches, with emphasis on the optical effects of fingerprints, and on techniques for optimizing the interpret- ability of rapidly time changing numeric
A design and evaluation of layered matrix tablet formulations of metoprolol tartrate.
Baloğlu, Esra; Senyiğit, Taner
2010-06-01
The aim of this paper was to evaluate the performance of different swellable polymers in the form of layered matrix tablets to provide controlled therapeutic effect of metoprolol tartrate for twice daily administration. Seven different swellable polymers (carrageenan, hydroxypropylmethyl cellulose, pectin, guar gum, xanthan gum, chitosan, and ethyl cellulose) were evaluated alone or in combination as release-retardant layer. Tablets were tested for weight variation, hardness, diameter/thickness ratio, friability, and drug content uniformity and subjected to in vitro drug-release studies. In addition, the target-release profile of metoprolol tartrate was plotted using its clinical pharmacokinetic data, and the release profiles of the tablets were evaluated in relation to the plotted target release profile. Carrageenan was determined as the best polymer in two-layered matrix tablet formulations due to its better accordance to the target release profile and was selected for preparing three-layered matrix tablets. Carrageenan formulations exhibited super case II release mechanism. Accelerated stability testing was performed on two- and three-layered matrix tablet formulations of carrageenan. The tablets were stored at 25 degrees C/60% relative humidity and 40 degrees C/75% relative humidity for 6 months and examined for physical appearance, drug content, and release characteristics. At the end of the storage time, formulations showed no change either in physical appearance, drug content, or drug-release profile. These results demonstrated the suitability of three-layered tablet formulation of carrageenan to provide controlled release and improved linearity for metoprolol tartrate in comparison to two-layered tablet formulation.
Choi, Du Hyung; Lim, Jun Yeul; Shin, Sangmun; Choi, Won Jun; Jeong, Seong Hoon; Lee, Sangkil
2014-10-01
To investigate the effects of hydrophilic polymers on the matrix system, an experimental design method was developed to integrate response surface methodology and the time series modeling. Moreover, the relationships among polymers on the matrix system were studied with the evaluation of physical properties including water uptake, mass loss, diffusion, and gelling index. A mixture simplex lattice design was proposed while considering eight input control factors: Polyethylene glycol 6000 (x1 ), polyethylene oxide (PEO) N-10 (x2 ), PEO 301 (x3 ), PEO coagulant (x4 ), PEO 303 (x5 ), hydroxypropyl methylcellulose (HPMC) 100SR (x6 ), HPMC 4000SR (x7 ), and HPMC 10(5) SR (x8 ). With the modeling, optimal formulations were obtained depending on the four types of targets. The optimal formulations showed the four significant factors (x1 , x2 , x3 , and x8 ) and other four input factors (x4 , x5 , x6 , and x7 ) were not significant based on drug release profiles. Moreover, the optimization results were analyzed with estimated values, targets values, absolute biases, and relative biases based on observed times for the drug release rates with four different targets. The result showed that optimal solutions and target values had consistent patterns with small biases. On the basis of the physical properties of the optimal solutions, the type and ratio of the hydrophilic polymer and the relationships between polymers significantly influenced the physical properties of the system and drug release. This experimental design method is very useful in formulating a matrix system with optimal drug release. Moreover, it can distinctly confirm the relationships between excipients and the effects on the system with extensive and intensive evaluations.
Chin-Pampillo, Juan Salvador; Ruiz-Hidalgo, Karla; Masís-Mora, Mario; Carazo-Rojas, Elizabeth; Rodríguez-Rodríguez, Carlos E
2015-12-01
Pesticide biopurification systems contain a biologically active matrix (biomixture) responsible for the accelerated elimination of pesticides in wastewaters derived from pest control in crop fields. Biomixtures have been typically prepared using the volumetric composition 50:25:25 (lignocellulosic substrate/humic component/soil); nonetheless, formal composition optimization has not been performed so far. Carbofuran is an insecticide/nematicide of high toxicity widely employed in developing countries. Therefore, the composition of a highly efficient biomixture (composed of coconut fiber, compost, and soil, FCS) for the removal of carbofuran was optimized by means of a central composite design and response surface methodology. The volumetric content of soil and the ratio coconut fiber/compost were used as the design variables. The performance of the biomixture was assayed by considering the elimination of carbofuran, the mineralization of (14)C-carbofuran, and the residual toxicity of the matrix, as response variables. Based on the models, the optimal volumetric composition of the FCS biomixture consists of 45:13:42 (coconut fiber/compost/soil), which resulted in minimal residual toxicity and ∼99% carbofuran elimination after 3 days. This optimized biomixture considerably differs from the standard 50:25:25 composition, which remarks the importance of assessing the performance of newly developed biomixtures during the design of biopurification systems.
NASA Astrophysics Data System (ADS)
Poria, Suswagata; Sahoo, Prasanta; Sutradhar, Goutam
2016-09-01
The present study outlines the use of Taguchi parameter design to minimize the wear performance of Al-TiB2 metal matrix composites by optimizing tribological process parameters. Different weight percentages of micro-TiB2 powders with average sizes of 5-40 micron are incorporated into molten LM4 aluminium matrix by stir casting method. The wear performance of Al-TiB2 composites is evaluated in a block-on-roller type Multitribo tester at room temperature. Three parameters viz. weight percentage of TiB2, load and speed are considered with three levels each at the time of experiment. A L27 orthogonal array is used to carry out experiments accommodating all the factors and their levels including their interaction effects. Optimal combination of parameters for wear performance is obtained by Taguchi analysis. Analysis of variance (ANOVA) is used to find out percentage contribution of each parameter and their interaction also on wear performance. Weight percentage of TiB2 is forced to be the most effective parameter in controlling wear behaviour of Al-TiB2 metal matrix composite.
NASA Technical Reports Server (NTRS)
Silvester, M. E.; Fitch, C. M.
1974-01-01
This paper describes matrix methods that have been developed for calculating compressible flow on a blade-to-blade surface of revolution. The methods have been fully tested to date only for the design of plane cascades to prescribed blade surface distributions; the methods will be illustrated here for that problem only. Similar methods are presently being applied to both the direct and indirect problems and for flow on arbitrary surfaces of revolution in annular cascades with stream sheet thickness variations. It is believed that by such methods, both the direct and indirect calculations can be reduced to about 60 to 90 seconds of computing.
Lornoxicam gastro retentive floating matrix tablets: Design and in vitro evaluation
Sathiyaraj, S.; Devi, Ramya D.; Hari, Vedha B. N.
2011-01-01
The objective of this present investigation is to prolong the gastric residence time of Lornoxicam by fabricating it into a floating sustained release matrix tablets. Lornoxicam, a potent oxicam group of non-steroidal anti-inflammatory drugs, suffers from relatively short half life of 2 to 3 hrs showing maximal absorption in proximal gastro intestinal tract region necessitating its need to be formulated as a floating sustained release matrix tablets. In this current investigation, hydroxyl propyl methyl cellulose K15M, a high viscous grade polymer with apparent viscosity of 15,000 cps, was kept as a variable (10-50%) and calcium carbonate (13%) was used as a gas generator. The prepared blends were subjected for its pre-formulation characterization. The directly compressed tablets were evaluated for physical parameters such as weight uniformity, hardness, friability, drug content, in-vitro buoyancy with axial and radial enlargement measurement, swelling index. From the investigation it was observed that the buoyancy lasted for up to 24 hrs. Fourier transform infra-red spectroscopy peaks assured the compatibility of the drug with excipients and confirmed the presence of pure drug in the formulation. It was supported by in-vitro dissolution studies; and the dissolution data was subjected to various release kinetic models to understand the mechanism of drug release. PMID:22171312
Pan, Houwen Matthew; Yu, Han; Guigas, Gernot; Fery, Andreas; Weiss, Matthias; Patzel, Volker; Trau, Dieter
2017-02-15
Hydrogels with complex internal structures are required for advanced drug delivery systems and tissue engineering or used as inks for 3D printing. However, hydrogels lack the tunability and diversity of polymeric shells and require complicated postsynthesis steps to alter its structure or properties. We report on the first integrated approach to assemble and design polymeric shells to take on various complex structures and functions such as multilayer nanofilms, multidensity immobilization matrix, or multiadhesive chromatography resins via the tuning of four assembly parameters: (a) poly(allylamine) (PA) concentration, (b) number of poly(allylamine)/poly(styrenesulfonic acid) (PA/PSSA) incubations, (c) poly(allylamine) (PA) to poly(ethylene glycol) (PEG) grafting ratio, and (d) % H2O present during assembly. Our approach combines the complex 3D structures of hydrogels with the versatility of self-assembled polymeric layers. Polymeric shells produced from our method have a highly uniform material distribution and well-defined shell boundaries. Shell thickness, density, and adhesive properties are easily tunable. By virtue of such unique material features, we demonstrate that polymeric shells can be designed to expand beyond its conventional function as thin films and serve as immobilization matrix, chromatography resins, or even reaction compartments. This technique could also uncover interesting perspectives in the development of novel multimaterials for 3D printing to synthesize scaffolds at a higher order of complexity.
Liang, Lihua; Sun, Mingxiao; Shi, Hongyu; Luan, Tiantian
2017-01-01
Fin-angle feedback control is usually used in conventional fin stabilizers, and its actual anti-rolling effect is difficult to reach theoretical design requirements. Primarily, lift of control torque is a theoretical value calculated by static hydrodynamic characteristics of fin. However, hydrodynamic characteristics of fin are dynamic while fin is moving in waves. As a result, there is a large deviation between actual value and theoretical value of lift. Firstly, the reasons of deviation are analyzed theoretically, which could avoid a variety of interference factors and complex theoretical derivations. Secondly, a new device is designed for direct measurement of actual lift, which is composed of fin-shaft combined mechanism and sensors. This new device can make fin-shaft not only be the basic function of rotating fin, but also detect actual lift. Through analysis using stiffness matrix of Euler-Bernoulli beam, displacement of shaft-core end is measured instead of lift which is difficult to measure. Then quantitative relationship between lift and displacement is defined. Three main factors are analyzed with quantitative relationship. What is more, two installation modes of sensors and a removable shaft-end cover are proposed according to hydrodynamic characteristics of fin. Thus the new device contributes to maintenance and measurement. Lastly, the effectiveness and accuracy of device are verified by contrasting calculation and simulation on the basis of actual design parameters. And the new measuring lift method can be proved to be effective through experiments. The new device is achieved from conventional fin stabilizers. Accordingly, the reliability of original equipment is inherited. The alteration of fin stabilizers is minor, which is suitable for engineering application. In addition, the flexural properties of fin-shaft are digitized with analysis of stiffness matrix. This method provides theoretical support for engineering application by carrying out finite
Liang, Lihua; Sun, Mingxiao; Shi, Hongyu; Luan, Tiantian
2017-01-01
Fin-angle feedback control is usually used in conventional fin stabilizers, and its actual anti-rolling effect is difficult to reach theoretical design requirements. Primarily, lift of control torque is a theoretical value calculated by static hydrodynamic characteristics of fin. However, hydrodynamic characteristics of fin are dynamic while fin is moving in waves. As a result, there is a large deviation between actual value and theoretical value of lift. Firstly, the reasons of deviation are analyzed theoretically, which could avoid a variety of interference factors and complex theoretical derivations. Secondly, a new device is designed for direct measurement of actual lift, which is composed of fin-shaft combined mechanism and sensors. This new device can make fin-shaft not only be the basic function of rotating fin, but also detect actual lift. Through analysis using stiffness matrix of Euler-Bernoulli beam, displacement of shaft-core end is measured instead of lift which is difficult to measure. Then quantitative relationship between lift and displacement is defined. Three main factors are analyzed with quantitative relationship. What is more, two installation modes of sensors and a removable shaft-end cover are proposed according to hydrodynamic characteristics of fin. Thus the new device contributes to maintenance and measurement. Lastly, the effectiveness and accuracy of device are verified by contrasting calculation and simulation on the basis of actual design parameters. And the new measuring lift method can be proved to be effective through experiments. The new device is achieved from conventional fin stabilizers. Accordingly, the reliability of original equipment is inherited. The alteration of fin stabilizers is minor, which is suitable for engineering application. In addition, the flexural properties of fin-shaft are digitized with analysis of stiffness matrix. This method provides theoretical support for engineering application by carrying out finite
Control Systems Analysis and Design via Matrix Inequalities and Interior Point Methods
2007-11-02
Springer-Verlag, 4th edition, 1997. [JBK+96] G. B. Jävorzky, S. Boyd, I. Kollär, L. Vandenberghe, and S.-P. Wu. Opti- mal excitation signal design for...multiple-output channels. To appear in IEEE GLOBECOM, 1998. [PS96] B. W. Parkinson and J. J. Spilker, Jr. Global positioning system : theory and
ERIC Educational Resources Information Center
Tsai, Kuan Chen
2016-01-01
The purpose of the present study is to explore to what extent the use of a more structured mode of assessing creative products--specifically, the CPAM--could beneficially influence design students' product creativity and creative processes. For this qualitative inquiry, following our CPAM-based intervention, students wrote reflective papers in…
Kennedy, Kelsey M; Bhaw-Luximon, Archana; Jhurry, Dhanjay
2017-03-01
Engineered scaffolds produced by electrospinning of biodegradable polymers offer a 3D, nanofibrous environment with controllable structural, chemical, and mechanical properties that mimic the extracellular matrix of native tissues and have shown promise for a number of tissue engineering applications. The microscale mechanical interactions between cells and electrospun matrices drive cell behaviors including migration and differentiation that are critical to promote tissue regeneration. Recent developments in understanding these mechanical interactions in electrospun environments are reviewed, with emphasis on how fiber geometry and polymer structure impact on the local mechanical properties of scaffolds, how altering the micromechanics cues cell behaviors, and how, in turn, cellular and extrinsic forces exerted on the matrix mechanically remodel an electrospun scaffold throughout tissue development. Techniques used to measure and visualize these mechanical interactions are described. We provide a critical outlook on technological gaps that must be overcome to advance the ability to design, assess, and manipulate the mechanical environment in electrospun scaffolds toward constructs that may be successfully applied in tissue engineering and regenerative medicine.
Jiang, Hong; Zuo, Yi; Zhang, Li; Li, Jidong; Zhang, Aiming; Li, Yubao; Yang, Xiaochao
2014-03-01
Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.
Design of indomethacin-loaded nanoparticles: effect of polymer matrix and surfactant
Dupeyrón, Danay; Kawakami, Monique; Ferreira, Adriana M; Cáceres-Vélez, Paolin Rocio; Rieumont, Jacques; Azevedo, Ricardo Bentes; Carvalho, José Carlos T
2013-01-01
Despite recent advances in nonsteroidal anti-inflammatory drug (NSAID) formulations, the design of targeted delivery systems to improve the efficacy and reduce side effects of NSAIDs continues to be a focus of much research. Enteric nanoparticles have been recognized as a potential system to reduce gastrointestinal irritations caused by NSAIDs. The aim of this study was to evaluate the effect of EUDRAGIT® L100, polyethylene glycol, and polysorbate 80 on encapsulation efficiency of indomethacin within enteric nanoparticles. Formulations were developed based on a multilevel factorial design (three factors, two levels). The amount of polyethylene glycol was shown to be the factor that had the greatest influence on the encapsulation efficiency (evaluated response) at 95% confidence level. Some properties of nanoparticles like process yield, drug–polymer interaction, particle morphology, and in vitro dissolution profile, which could affect biological performance, have also been evaluated. PMID:24092971
NASA Technical Reports Server (NTRS)
Crivello, James V.
2000-01-01
Several new series of novel, high reactivity epoxy resins are described which are designed specifically for the fabrication of high performance carbon fiber reinforced composites for commercial aircraft structural applications using cationic UV and e-beam curing. The objective of this investigation is to provide resin matrices which rapidly and efficiently cure under low e-beam doses which are suitable to high speed automated composite fabrication techniques such as automated tape and tow placement. It was further the objective of this work to provide resins with superior thermal, oxidative and atomic oxygen resistance.
2007-06-01
1: Interview with: Jane Doe ACME Corporation Chief Engineer Date: 11/2/01 Q: What are some of your challenges in coordinating design activities? Codes...Canwnentfl Jb3r ATh level yet so obviously it wasn’t an R, an A-5-R issue)......... Stakeholders. MD> comunicates with> Q. Do you have contact with any...some ways, the goal was to develop a suite of systems that were akin to the weapons of corporate warfare, the Blackberry and Treo (other multipurpose
Accurate Shim-Coil Design and Magnet-Field Profiling by a Power-Minimization-Matrix Method
NASA Astrophysics Data System (ADS)
Hoult, D. I.; Deslauriers, R.
The design of a single correction coil that annuls, with minimal power consumption, the field inhomogeneity associated with a specific magnet is described. The design strategy used is also shown to be advantageous for the production of high-accuracy, power-efficient shim coils, "drift-free" shims (i.e., no slow mainfield drift following a change of shim current), and high-homogeneity "shielded" magnets. Starting with a description of field inhomogeneity in a spherical-harmonic basis set, the cylindrical-surface current-density function needed to annul inhomogeneity is calculated, with minimization of electrical power dissipation, by a simple matrix formulation. The inclusion of design constraints, such as the annulment of mutual inductance between zonal shims and the magnet, is highlighted and production of the current-density function with both wire and cut sheet is briefly discussed. Insights are presented as to why the method, unlike some, gives a smooth current-density function lacking spurious high-frequency ripples, and experimental and numerical tests are reported that reveal the efficacy of the computational procedures.
NASA Astrophysics Data System (ADS)
Guo, Rongyan; Wang, Hongyan
2016-07-01
In this work, the issue of robust waveform optimization is addressed in the presence of clutter to improve the worst-case estimation accuracy for collocated multiple-input multiple-output (MIMO) radar. Robust design is necessary due to the fact that waveform design may be sensitive to uncertainties in the initial parameter estimates. Following the min-max approach, the robust waveform covariance matrix design is formulated here on the basis of Cramér-Rao Bound to ease this sensitivity systematically for improving the worst-case accuracy. To tackle the resultant complicated and nonlinear problem, a new diagonal loading (DL)-based iterative approach is developed, in which the inner optimization problem can first be decomposed to some independent subproblems by using the Hadamard's inequality, and then these subproblems can be reformulated into convex issues by using DL method, as well as the outer optimization problem can also be relaxed to a convex issue by translating the nonlinear function into a linear one, and, hence, both of them can be solved very effectively. An optimal solution to the original problem can be obtained via the least-squares fitting of the solution acquired by the iterative approach. Numerical simulations show the efficiency of the proposed method.
The design and testing of a dual fiber textile matrix for accelerating surface hemostasis.
Fischer, Thomas H; Vournakis, John N; Manning, James E; McCurdy, Shane L; Rich, Preston B; Nichols, Timothy C; Scull, Christopher M; McCord, Marian G; Decorta, Joseph A; Johnson, Peter C; Smith, Carr J
2009-10-01
The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions.
The Design and Testing of a Dual Fiber Textile Matrix for Accelerating Surface Hemostasis
Fischer, Thomas H.; Vournakis, John N.; Manning, James E.; McCurdy, Shane L.; Rich, Preston B.; Nichols, Timothy C.; Scull, Christopher M.; McCord, Marian G.; Decorta, Joseph A.; Johnson, Peter C.; Smith, Carr J.
2011-01-01
The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions. PMID:19489008
Zirehpour, Alireza; Rahimpour, Ahmad; Jahanshahi, Mohsen; Peyravi, Majid
2014-01-01
Olive oil mill wastewater (OMW) is a concentrated effluent with a high organic load. It has high levels of organic chemical oxygen demand (COD) and phenolic compounds. This study presents a unique process to treat OMW. The process uses ultrafiltration (UF) membranes modified by a functionalized multi wall carbon nano-tube (F-MWCNT). The modified tube has an inner diameter of 15-30 nm and is added to the OMW treatment process to improve performance of the membrane. Tests were done to evaluate the following operating parameters of the UF system; pressure, pH and temperature; also evaluated parameters of permeate flux, flux decline, COD removal and total phenol rejection. The Taguchi robust design method was applied for an optimization evaluation of the experiments. Variance (ANOVA) analysis was used to determine the most significant parameters affecting permeate flux, flux decline, COD removal and total phenols rejection. Results demonstrated coagulation and pH as the most important factors affecting permeate flux of the UF. Moreover, pH and F-MWCNT UF had significant positive effects on flux decline, COD removal and total phenols rejection. Based on the optimum conditions determined by the Taguchi method, evaluations for permeate flux tests; flux decline, COD removal and total phenols rejection were about 21.2 (kg/m(2) h), 12.6%, 72.6% and 89.5%, respectively. These results were in good agreement with those predicted by the Taguchi method (i.e.; 22.8 (kg/m(2) h), 11.9%, 75.8 and 94.7%, respectively). Mechanical performance of the membrane and its application for high organic wastewater treatment were determined as strong.
Low, Pearlie S J; Tjin, Monica S; Fong, Eileen
2015-06-11
Recombinant technology is a versatile platform to create novel artificial proteins with tunable properties. For the last decade, many artificial proteins that have incorporated functional domains derived from nature (or created de novo) have been reported. In particular, artificial extracellular matrix (aECM) proteins have been developed; these aECM proteins consist of biological domains taken from fibronectin, laminins and collagens and are combined with structural domains including elastin-like repeats, silk and collagen repeats. To date, aECM proteins have been widely investigated for applications in tissue engineering and wound repair. Recently, Tjin and coworkers developed integrin-specific aECM proteins designed for promoting human skin keratinocyte attachment and propagation. In their work, the aECM proteins incorporate cell binding domains taken from fibronectin, laminin-5 and collagen IV, as well as flanking elastin-like repeats. They demonstrated that the aECM proteins developed in their work were promising candidates for use as substrates in artificial skin. Here, we outline the design and construction of such aECM proteins as well as their purification process using the thermo-responsive characteristics of elastin.
Fuin, Niccolo; Pedemonte, Stefano; Arridge, Simon; Ourselin, Sebastien; Hutton, Brian F
2014-03-01
System designs in single photon emission tomography (SPECT) can be evaluated based on the fundamental trade-off between bias and variance that can be achieved in the reconstruction of emission tomograms. This trade off can be derived analytically using the Cramer-Rao type bounds, which imply the calculation and the inversion of the Fisher information matrix (FIM). The inverse of the FIM expresses the uncertainty associated to the tomogram, enabling the comparison of system designs. However, computing, storing and inverting the FIM is not practical with 3-D imaging systems. In order to tackle the problem of the computational load in calculating the inverse of the FIM, a method based on the calculation of the local impulse response and the variance, in a single point, from a single row of the FIM, has been previously proposed for system design. However this approximation (circulant approximation) does not capture the global interdependence between the variables in shift-variant systems such as SPECT, and cannot account e.g., for data truncation or missing data. Our new formulation relies on subsampling the FIM. The FIM is calculated over a subset of voxels arranged in a grid that covers the whole volume. Every element of the FIM at the grid points is calculated exactly, accounting for the acquisition geometry and for the object. This new formulation reduces the computational complexity in estimating the uncertainty, but nevertheless accounts for the global interdependence between the variables, enabling the exploration of design spaces hindered by the circulant approximation. The graphics processing unit accelerated implementation of the algorithm reduces further the computation times, making the algorithm a good candidate for real-time optimization of adaptive imaging systems. This paper describes the subsampled FIM formulation and implementation details. The advantages and limitations of the new approximation are explored, in comparison with the circulant
Di Bucchianico, Giuseppe; Camplone, Stefania; Picciani, Stefano; Vallese, Valeria
2012-01-01
The widespread sense of spatial disorientation that can be experienced in many public places (buildings and open spaces),generally depends on a design approach that doesn't take into account both the "communication skills" of the different parts of the spatial organization, both the variability of people and their ways of interacting with environments, orienteering themselves. Nevertheless, "not find the way" often has some obvious practical costs (loss of time, failure to achieve a target) and some more intangible, but no less important, emotional costs. That's why the design of signage systems must take into account both the specificities of places and the extreme variability of its users. The paper presents the results of a study on this specific issue. In particular, the study focuses on the description of some tools useful for the analysis and design of a signage system that is truly "for All".
BOGER, R.M.
2000-09-28
The DOE has identified a need to sample vapor space, exhaust ducts, supernate, sludge, and soft saltcake in waste tanks that store radioactive waste. This document provides the Design Compliance Matrix (DCM) for the Type 4 In-Situ Vapor Sampling (ISVS) system and the Grab Sampling System that are used for completing this type of sampling function. The DCM identifies the design requirements and the source of the requirements for the Type 4 ISVS system and the Grab Sampling system. The DCM is a single-source compilation design requirements for sampling and sampling support equipment and supports the configuration management of these systems.
Chandran, S.; Asghar, Laila F. A.; Mantha, Neelima
2008-01-01
Controlled release preparations have been reported to reduce the gastro irritant and ulcerogenic effects of non steroidal antiinflammatory drugs. In the present study, an attempt was made to develop matrix tablet-based controlled release formulations of ibuprofen, using ethyl cellulose as the rate-controlling polymer. In order to prevent initial release of the drug in the acidic environment of the stomach, cellulose acetate phthalate was incorporated in the matrix in varying amounts. It was found that with increasing the proportion of ethyl cellulose in the matrix, the drug release was extended for 14-16 h. Incorporation of cellulose acetate phthalate in ethyl cellulose matrix provided very low initial release of the drug in the first 2-3 h followed by enhanced release rate in alkaline medium owing to the high solubility of cellulose acetate phthalate at basic pH which led to creation of a porous matrix. It was concluded that combination of cellulose acetate phthalate with ethyl cellulose in the matrix base can be an effective means of developing a controlled release formulation of ibuprofen with very low initial release followed with controlled release up to 14-16 h. PMID:21394255
The intraclass covariance matrix.
Carey, Gregory
2005-09-01
Introduced by C.R. Rao in 1945, the intraclass covariance matrix has seen little use in behavioral genetic research, despite the fact that it was developed to deal with family data. Here, I reintroduce this matrix, and outline its estimation and basic properties for data sets on pairs of relatives. The intraclass covariance matrix is appropriate whenever the research design or mathematical model treats the ordering of the members of a pair as random. Because the matrix has only one estimate of a population variance and covariance, both the observed matrix and the residual matrix from a fitted model are easy to inspect visually; there is no need to mentally average homologous statistics. Fitting a model to the intraclass matrix also gives the same log likelihood, likelihood-ratio (LR) chi2, and parameter estimates as fitting that model to the raw data. A major advantage of the intraclass matrix is that only two factors influence the LR chi2--the sampling error in estimating population parameters and the discrepancy between the model and the observed statistics. The more frequently used interclass covariance matrix adds a third factor to the chi2--sampling error of homologous statistics. Because of this, the degrees of freedom for fitting models to an intraclass matrix differ from fitting that model to an interclass matrix. Future research is needed to establish differences in power-if any--between the interclass and the intraclass matrix.
NASA Technical Reports Server (NTRS)
Cannone, Jaime J.; Barnes, Cindy L.; Achari, Aniruddha; Kundrot, Craig E.; Whitaker, Ann F. (Technical Monitor)
2001-01-01
The Sparse Matrix approach for obtaining lead crystallization conditions has proven to be very fruitful for the crystallization of proteins and nucleic acids. Here we report a Sparse Matrix developed specifically for the crystallization of protein-DNA complexes. This method is rapid and economical, typically requiring 2.5 mg of complex to test 48 conditions. The method was originally developed to crystallize basic fibroblast growth factor (bFGF) complexed with DNA sequences identified through in vitro selection, or SELEX, methods. Two DNA aptamers that bind with approximately nanomolar affinity and inhibit the angiogenic properties of bFGF were selected for co-crystallization. The Sparse Matrix produced lead crystallization conditions for both bFGF-DNA complexes.
Reliability of using a fixed matrix in coregistration of combined PET-MRI in a split magnet design.
Sawiak, Sj; Hawkes, Rc; Ansorge, Re; Carpenter, Ta
2013-02-21
We consider the effects of using a fixed linear transformation to match positron emission tomography (PET) and magnetic resonance imaging (MRI) data acquired simultaneously using a split-magnet system. Estimates of the frequency offset in MRI scans were used to calculate geometric variability in MRI reconstruction as a consequence of mis-setting this parameter in addition to repeated estimation of the transformation matrix by manual measurements. None of the measured variability approached the resolution of the PET images so we concluded that a fixed matrix can be reliably used in such a system.
Patel, Dm; Patel, Bk; Patel, Ha; Patel, Cn
2011-07-01
The objective of the present study was to evaluate the effect of sintering condition on matrix formation and subsequent drug release from polymer matrix tablet for controlled release. The present study highlights the use of a microwave oven for the sintering process in order to achieve more uniform heat distribution with reduction in time required for sintering. We could achieve effective sintering within 8 min which is very less compared to conventional hot air oven sintering. The tablets containing the drug (propranolol hydrochloride) and sintering polymer (eudragit S-100) were prepared and kept in a microwave oven at 540 watt, 720 watt and 900 watt power for different time periods for sintering. The sintered tablets were evaluated for various tablet characteristics including dissolution study. Tablets sintered at 900 watt power for 8 min gave better dissolution profile compared to others. We conclude that microwave oven sintering is better than conventional hot air oven sintering process in preparation of controlled release tablets.
Markowski, Adam S; Mannan, M Sam
2008-11-15
A risk matrix is a mechanism to characterize and rank process risks that are typically identified through one or more multifunctional reviews (e.g., process hazard analysis, audits, or incident investigation). This paper describes a procedure for developing a fuzzy risk matrix that may be used for emerging fuzzy logic applications in different safety analyses (e.g., LOPA). The fuzzification of frequency and severity of the consequences of the incident scenario are described which are basic inputs for fuzzy risk matrix. Subsequently using different design of risk matrix, fuzzy rules are established enabling the development of fuzzy risk matrices. Three types of fuzzy risk matrix have been developed (low-cost, standard, and high-cost), and using a distillation column case study, the effect of the design on final defuzzified risk index is demonstrated.
NASA Technical Reports Server (NTRS)
Hou, Tan-Hung
2014-01-01
For the fabrication of resin matrix fiber reinforced composite laminates, a workable cure cycle (i.e., temperature and pressure profiles as a function of processing time) is needed and is critical for achieving void-free laminate consolidation. Design of such a cure cycle is not trivial, especially when dealing with reactive matrix resins. An empirical "trial and error" approach has been used as common practice in the composite industry. Such an approach is not only costly, but also ineffective at establishing the optimal processing conditions for a specific resin/fiber composite system. In this report, a rational "processing science" based approach is established, and a universal cure cycle design protocol is proposed. Following this protocol, a workable and optimal cure cycle can be readily and rationally designed for most reactive resin systems in a cost effective way. This design protocol has been validated through experimental studies of several reactive polyimide composites for a wide spectrum of usage that has been documented in the previous publications.
NASA Astrophysics Data System (ADS)
Ma, G. Z.; Chen, D.
2016-11-01
A Cu49Zr51 intermetallic is used as a base for synthesizing metallic glasses and composites with glass matrixes [(Cu49Zr51)100 - x Al x , where x = 0, 2, 4, 6, 8, 10 and 12 at.%]. The introduction of aluminum raises the microhardness and the ultimate compressive strength. In addition, the suppression of formation of crystalline phase upon the introduction of 8 at.% Al provides a glass-like structure in alloy (Cu49Zr51)92Al8. The formation of the glass-like structure is discussed within the concept of competitive nucleation of different intermetallics.
Liu, Hsia-Wei; Chaw, Jen-Ray; Shih, Yu-Chao; Huang, Ching-Cheng
2014-01-01
Hydroxypropyl methylcellulose (HPMC) was employed in this study to design controllable drug release systems because of its non-toxic nature, swelling properties. New interpenetrating polymer networks (IPN) of HPMC / tri-isocyanate crosslinked polyurethane (TCPU) could be prepared on the surfaces of IPN materials. To design "Novel Drug-carrying Matrix Systems", incorporation of novel structure is important to the possible formation of drug-carrying spaces within the material, which was achieved by using Tris (6-isocyanatohexyl) isocyanurate with three soft hexyl arms in this study. A series of novel drug-carrying matrix systems prepared by crosslinking reaction could be candidates for an excellent and smart potential material. When the polymeric networks were established on the surfaces of resulting materials, the developed hydrophilic interpenetrating polymeric structures of HPMC/ polyurethane could provide good wettability to the wound dressings, particularly for moisture healing application. The materials containing HPMC/polyurethane networks using 1% cross-linking agent showed a water uptake value of 5.1% after one hour, which has great potential for use as wound dressings for moisture healing. Furthermore, a new drug delivery system of hydrophilic IPN was successfully designed and established.
Nelson, Clarke; Khan, Yusuf; Laurencin, Cato T
2014-11-01
Bone is an essential organ for health and quality of life. Due to current shortfalls in therapy for bone tissue engineering, scientists have sought the application of synthetic materials as bone graft substitutes. As a composite organic/inorganic material with significant extra cellular matrix (ECM), one way to improve bone graft substitutes may be to engineer a synthetic matrix that is influenced by the physical appearance of natural ECM networks. In this work, the authors evaluate composite, hybrid scaffolds for bone tissue engineering based on composite ceramic/polymer microsphere scaffolds with synthetic ECM-mimetic networks in their pore spaces. Using thermally induced phase separation, nanoscale fibers were deposited in the pore spaces of structurally sound microsphere-based scaffold with a density proportionate to the initial polymer concentration. Porosimetry and mechanical testing indicated no significant changes in overall pore characteristics or mechanical integrity as a result of the fiber deposition process. These scaffolds displayed adequate mechanical integrity on the scale of human trabecular bone and supported the adhesion and proliferation of cultured mouse calvarial osteoblasts. Drawing from natural cues, these scaffolds may represent a new avenue forward for advanced bone tissue engineering scaffolds.
Ulu, Ahmet; Koytepe, Suleyman; Ates, Burhan
2016-11-20
We prepared biodegradable P(MAA-co-MMA)-starch composite as carrier matrix for the immobilization of l-asparaginase (l-ASNase), an important chemotherapeutic agent in acute lymphoblastic leukemia. Chemical characteristics and thermal stability of the prepared composites were determined by FT-IR, TGA, DTA and, DSC, respectively. Also, biodegradability measurements of P(MAA-co-MMA)-starch composites were carried out to examine the effects of degradation of the starch. Then, l-ASNase was immobilized on the P(MAA-co-MMA)-starch composites. The surface morphology of the composite before and after immobilization was characterized by SEM, EDX, and AFM. The properties of the immobilized l-ASNase were investigated and compared with the free enzyme. The immobilized l-ASNase had better showed thermal and pH stability, and remained stable after 30days of storage at 25°C. Thus, based on the findings of the present work, the P(MAA-co-MMA)-starch composite can be exploited as the biocompatible matrix used for l-ASNase immobilization for medical applications due to biocompatibility and biodegradability.
NASA Astrophysics Data System (ADS)
Pons Abenza, A.; Martinez-Mendoza, M.; Quesada Pereira, F. D.; Alvarez-Melcon, A.
2016-07-01
This paper presents for the first time the design of manifold multiplexers in waveguide technology using all-inductive dual-mode channel filters. It is shown that very complex transfer functions can be implemented for the channels, using simple structures that can be analyzed and manufactured with increased simplicity as compared to other commercial solutions. In this paper we adapt a standard design technique for manifold multiplexers to the new proposed technology. The paper is illustrated with the design of two triplexers, using H-type and E-type waveguide manifolds, with filters implementing two transmission zeros in the insertion loss response for maximum isolation between channels. Results show that the procedure is indeed effective and can be used for the design of practical multiplexer configurations.
Moeyaert, Mariola; Ugille, Maaike; Ferron, John M; Beretvas, S Natasha; Van den Noortgate, Wim
2014-09-01
The quantitative methods for analyzing single-subject experimental data have expanded during the last decade, including the use of regression models to statistically analyze the data, but still a lot of questions remain. One question is how to specify predictors in a regression model to account for the specifics of the design and estimate the effect size of interest. These quantitative effect sizes are used in retrospective analyses and allow synthesis of single-subject experimental study results which is informative for evidence-based decision making, research and theory building, and policy discussions. We discuss different design matrices that can be used for the most common single-subject experimental designs (SSEDs), namely, the multiple-baseline designs, reversal designs, and alternating treatment designs, and provide empirical illustrations. The purpose of this article is to guide single-subject experimental data analysts interested in analyzing and meta-analyzing SSED data.
Srichan, Tharatree; Phaechamud, Thawatchai
2017-01-01
An in situ forming gel is a dosage form which is promised for site-specific therapy such as periodontal pocket of periodontitis treatment. Ethylcellulose, bleached shellac, and Eudragit RS were applied in this study as a polymeric matrix for in situ forming gel employing N-methyl pyrrolidone (NMP) as solvent. Solutions comprising ethylcellulose, bleached shellac, and Eudragit RS in NMP were evaluated for viscosity, rheology, and rate of water penetration. Ease of administration by injection was determined as the force required to expel polymeric solutions through a needle using texture analyzer. In vitro gel formation and in vitro gel degradation were conducted after injection into phosphate buffer solution pH 6.8. Ethylcellulose, bleached shellac, and Eudragit RS could form the in situ gel, in vitro. Gel viscosity and pH value depended on percentage amount of the polymer, whereas the water diffusion at early period likely relied on types of polymer. Furthermore, the solutions containing higher polymer concentration exhibited the lower degree of degradation. All the preparations were acceptable as injectable dosage forms because the applied force was lower than 50 N. All of them inhibited Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans, and Porphyrommonas gingivalis growth owing to antimicrobial activity of NMP which exhibited a potential use for periodontitis treatment. Moreover, the developed systems presented as the solvent exchange induced in situ forming gel and showed capability to be incorporated with the suitable antimicrobial active compounds for periodontitis treatment which should be further studied.
NASA Technical Reports Server (NTRS)
Whitacre, J.; West, W. C.; Mojarradi, M.; Sukumar, V.; Hess, H.; Li, H.; Buck, K.; Cox, D.; Alahmad, M.; Zghoul, F. N.; Jackson, J.; Terry, S.; Blalock, B.
2003-01-01
This paper presents a design approach to help attain any random grouping pattern between the microbatteries. In this case, the result is an ability to charge microbatteries in parallel and to discharge microbatteries in parallel or pairs of microbatteries in series.
Antonuk, Larry E.; Zhao, Qihua; El-Mohri, Youcef; Du, Hong; Wang, Yi; Street, Robert A.; Ho, Jackson; Weisfield, Richard; Yao, William
2009-01-01
Active matrix flat-panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and∕or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from 75 to 127 μm. For each design, detailed measurements of fundamental pixel-level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of 127 μm pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of ∼80% (thereby assuring improved x-ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and 90 μm pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or continuous
Caves, Jeffrey M; Kumar, Vivek A; Martinez, Adam W; Kim, Jeong; Ripberger, Carrie M; Haller, Carolyn A; Chaikof, Elliot L
2010-09-01
Collagen and elastin networks contribute to highly specialized biomechanical responses in numerous tissues and species. Biomechanical properties such as modulus, elasticity, and strength ultimately affect tissue function and durability, as well as local cellular behavior. In the case of vascular bypass grafts, compliance at physiologic pressures is correlated with increased patency due to a reduction in anastomotic intimal hyperplasia. In this report, we combine extracellular matrix (ECM) protein analogues to yield multilamellar vascular grafts comprised of a recombinant elastin-like protein matrix reinforced with synthetic collagen microfibers. Structural analysis revealed that the fabrication scheme permits a range of fiber orientations and volume fractions, leading to tunable mechanical properties. Burst strengths of 239-2760 mm Hg, compliances of 2.8-8.4%/100 mm Hg, and suture retention strengths of 35-192 gf were observed. The design most closely approximating all target criteria displayed a burst strength of 1483 +/- 143 mm Hg, a compliance of 5.1 +/- 0.8%/100 mm Hg, and a suture retention strength of 173 +/- 4 gf. These results indicate that through incorporation of reinforcing collagen microfibers, recombinant elastomeric protein-based biomaterials can play a significant role in load bearing tissue substitutes. We believe that similar composites can be incorporated into tissue engineering schemes that seek to integrate cells within the structure, prior to or after implantation in vivo.
Adler, Camille; Schönenberger, Monica; Teleki, Alexandra; Kuentz, Martin
2016-02-29
Amorphous solid dispersions have for many years been a focus in oral formulations, especially in combination with a hot-melt extrusion process. The present work targets a novel approach with a system based on a fatty acid, a polymer and an inorganic carrier. It was intended to adsorb the acidic lipid by specific molecular interactions onto the solid carrier to design disorder in the alkyl chains of the lipid. Such designed lipid microdomains (DLM) were created as a new microstructure to accommodate a compound in a solid dispersion. Vibrational spectroscopy, X-ray powder diffraction, atomic force microscopy as well as electron microscopic imaging were employed to study a system of stearic acid, hydroxypropylcellulose and aluminum magnesium silicate. β-carotene was used as a poorly water-soluble model substance that is difficult to formulate with conventional solid dispersion formulations. The results indicated that the targeted molecular excipient interactions indeed led to DLMs for specific compositions. The different methods provided complementary aspects and important insights into the created microstructure. The novel delivery system appeared to be especially promising for the formulation of oral compounds that exhibit both high crystal energy and lipophilicity.
NASA Astrophysics Data System (ADS)
Lopes, D. F.; Oliveira, M. D.; Costa, C. A. Bana e.
2015-05-01
Risk matrices (RMs) are commonly used to evaluate health and safety risks. Nonetheless, they violate some theoretical principles that compromise their feasibility and use. This study describes how multiple criteria decision analysis methods have been used to improve the design and the deployment of RMs to evaluate health and safety risks at the Occupational Health and Safety Unit (OHSU) of the Regional Health Administration of Lisbon and Tagus Valley. ‘Value risk-matrices’ (VRMs) are built with the MACBETH approach in four modelling steps: a) structuring risk impacts, involving the construction of descriptors of impact that link risk events with health impacts and are informed by scientific evidence; b) generating a value measurement scale of risk impacts, by applying the MACBETH-Choquet procedure; c) building a system for eliciting subjective probabilities that makes use of a numerical probability scale that was constructed with MACBETH qualitative judgments on likelihood; d) and defining a classification colouring scheme for the VRM. A VRM built with OHSU members was implemented in a decision support system which will be used by OHSU members to evaluate health and safety risks and to identify risk mitigation actions.
NASA Astrophysics Data System (ADS)
Craps, Ben; Evnin, Oleg; Nguyen, Kévin
2017-02-01
Matrix quantum mechanics offers an attractive environment for discussing gravitational holography, in which both sides of the holographic duality are well-defined. Similarly to higher-dimensional implementations of holography, collapsing shell solutions in the gravitational bulk correspond in this setting to thermalization processes in the dual quantum mechanical theory. We construct an explicit, fully nonlinear supergravity solution describing a generic collapsing dilaton shell, specify the holographic renormalization prescriptions necessary for computing the relevant boundary observables, and apply them to evaluating thermalizing two-point correlation functions in the dual matrix theory.
Orbe, Josune; Sánchez-Arias, Juan A; Rabal, Obdulia; Rodríguez, José A; Salicio, Agustina; Ugarte, Ana; Belzunce, Miriam; Xu, Musheng; Wu, Wei; Tan, Haizhong; Ma, Hongyu; Páramo, José A; Oyarzabal, Julen
2015-03-12
Growing evidence suggests that matrix metalloproteinases (MMP) are involved in thrombus dissolution; then, considering that new therapeutic strategies are required for controlling hemorrhage, we hypothesized that MMP inhibition may reduce bleeding by delaying fibrinolysis. Thus, we designed and synthesized a novel series of MMP inhibitors to identify potential candidates for acute treatment of bleeding. Structure-based and knowledge-based strategies were utilized to design this novel chemical series, α-spiropiperidine hydroxamates, of potent and soluble (>75 μg/mL) pan-MMP inhibitors. The initial hit, 12, was progressed to an optimal lead 19d. Racemic 19d showed a remarkable in vitro phenotypic response and outstanding in vivo efficacy; in fact, the mouse bleeding time at 1 mg/kg was 0.85 min compared to 29.28 min using saline. In addition, 19d displayed an optimal ADME and safety profile (e.g., no thrombus formation). Its corresponding enantiomers were separated, leading to the preclinical candidate 5 (described in Drug Annotations series, J. Med. Chem. 2015, ).
Tuzlakoglu, Kadriye; Santos, Marina I; Neves, Nuno; Reis, Rui L
2011-02-01
Mimicking the structural organization and biologic function of natural extracellular matrix has been one of the main goals of tissue engineering. Nevertheless, the majority of scaffolding materials for bone regeneration highlights biochemical functionality in detriment of mechanical properties. In this work we present a rather innovative construct that combines in the same structure electrospun type I collagen nanofibers with starch-based microfibers. These combined structures were obtained by a two-step methodology and structurally consist in a type I collagen nano-network incorporated on a macro starch-based support. The morphology of the developed structures was assessed by several microscopy techniques and the collagenous nature of the nano-network was confirmed by immunohistochemistry. In addition, and especially regarding the requirements of large bone defects, we also successfully introduced the concept of layer by layer, as a way to produce thicker structures. In an attempt to recreate bone microenvironment, the design and biochemical composition of the combined structures also envisioned bone-forming cells and endothelial cells (ECs). The inclusion of a type I collagen nano-network induced a stretched morphology and improved the metabolic activity of osteoblasts. Regarding ECs, the presence of type I collagen on the combined structures provided adhesive support and obviated the need of precoating with fibronectin. It was also importantly observed that ECs on the nano-network organized into circular structures, a three-dimensional arrangement distinct from that observed for osteoblasts and resembling the microcappillary-like organizations formed during angiogenesis. By providing simultaneously physical and chemical cues for cells, the herein-proposed combined structures hold a great potential in bone regeneration as a man-made equivalent of extracellular matrix.
Metz, William C.; Metz, W. Chris; Mitrani, Jacques E.; Hewett, Jr., Paul L.; Jones, Christopher A.
2004-12-31
Sync Matrix provides a graphic display of the relationships among all of the response activities of each jurisdiction. This is accomplished through software that organizes and displays the activities by jurisdiction, function, and time for easy review and analysis. The software can also integrate the displays of multiple jurisdictions to allow examination of the total response.
Qin, Jinwen; Liu, Bing; Cao, Minhua
2016-12-19
Tin anode materials have attracted much attention owing to their high theoretical capacity, although rapid capacity fade is commonly observed mainly because of structural degradation resulting from volume expansion. Herein, we report a versatile strategy based on a basil seed inspired design for constructing a monodisperse core-shell Sn@C hybrid confined in a carbon matrix (Sn basil seeds). Analogous to the structure of basil seeds soaked in water, Sn basil seeds are used to tackle the volume expansion problem in lithium-ion batteries. Monodisperse Sn cores are encapsulated by a thick carbon layer, which thus lowers the electrolyte contact area. The obtained Sn basil seeds are closely packed to construct a framework that supplies fast electron transport and provides a reinforced mechanical backbone. As a consequence, an ensemble of this hybrid network shows significantly enhanced lithium-storage performance with a high capacity of 870 mAh g(-1) at a current density of 0.4 A g(-1) over 600 cycles. After the intense cycling, the Sn cores transform into ultrafine nanocrystals with sizes of 3-6 nm. The structural and morphological evolution of the Sn cores can reasonably explain the gradual increase in the capacity and the long-term cycling ability of our Sn basil seeds.
Sanches, Livia Rentas; Seulin, Saskia Carolina; Leyton, Vilma; Paranhos, Beatriz Aparecida Passos Bismara; Pasqualucci, Carlos Augusto; Muñoz, Daniel Romero; Osselton, Michael David; Yonamine, Mauricio
2012-04-01
Undoubtedly, whole blood and vitreous humor have been biological samples of great importance in forensic toxicology. The determination of opiates and their metabolites has been essential for better interpretation of toxicological findings. This report describes the application of experimental design and response surface methodology to optimize conditions for enzymatic hydrolysis of morphine-3-glucuronide and morphine-6-glucuronide. The analytes (free morphine, 6-acetylmorphine and codeine) were extracted from the samples using solid-phase extraction on mixed-mode cartridges, followed by derivatization to their trimethylsilyl derivatives. The extracts were analysed by gas chromatography-mass spectrometry with electron ionization and full scan mode. The method was validated for both specimens (whole blood and vitreous humor). A significant matrix effect was found by applying the F-test. Different recovery values were also found (82% on average for whole blood and 100% on average for vitreous humor). The calibration curves were linear for all analytes in the concentration range of 10-1,500 ng/mL. The limits of detection ranged from 2.0 to 5.0 ng/mL. The method was applied to a case in which a victim presented with a previous history of opiate use.
NASA Technical Reports Server (NTRS)
Zhu, Dong-Ming; Choi, Sung R.; Ghosn, Louis J.; Miller, Robert A.
2004-01-01
Ceramic thermal/environmental barrier coatings for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability remains a major concern with the ever-increasing temperature requirements. Currently, advanced T/EBC systems, which typically include a high temperature capable zirconia- (or hahia-) based oxide top coat (thermal barrier) on a less temperature capable mullite/barium-strontium-aluminosilicate (BSAS)/Si inner coat (environmental barrier), are being developed and tested for higher temperature capability Sic combustor applications. In this paper, durability of several thermal/environmental barrier coating systems on SiC/SiC ceramic matrix composites was investigated under laser simulated engine thermal gradient cyclic, and 1650 C (3000 F) test conditions. The coating cracking and delamination processes were monitored and evaluated. The effects of temperature gradients and coating configurations on the ceramic coating crack initiation and propagation were analyzed using finite element analysis (FEA) models based on the observed failure mechanisms, in conjunction with mechanical testing results. The environmental effects on the coating durability will be discussed. The coating design approach will also be presented.
Performance Appraisal for Matrix Management.
ERIC Educational Resources Information Center
Edwards, M. R.; Sproull, J. Ruth
1985-01-01
A matrix management system designed for use by a highly technical nuclear weapons research and development facility to improve productivity and flexibility by the use of multiple authority, responsibility, and accountability relationships is described. (MSE)
Barry, Jeremy A.; Muddiman, David C.
2013-01-01
Design of experiments (DOE) is a systematic and cost-effective approach to system optimization by which the effects of multiple parameters and parameter interactions on a given response can be measured in few experiments. Herein, we describe the use of statistical DOE to improve a few of the analytical figures of merit of the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) source for mass spectrometry. In a typical experiment, bovine cytochrome c (~12 kDa) was ionized via electrospray, and equine cytochrome c (~12 kDa) was desorbed and ionized by IR-MALDESI such that the ratio of equine:bovine was used as a measure of the ionization efficiency of IR-MALDESI. This response was used to rank the importance of seven source parameters including flow rate, laser fluence, laser repetition rate, ESI emitter to mass spectrometer inlet distance, sample stage height, sample plate voltage, and the sample to mass spectrometer inlet distance. A screening fractional factorial DOE was conducted to designate which of the seven parameters induced the greatest amount of change in the response. These important parameters (flow rate, stage height, sample to mass spectrometer inlet distance, and laser fluence) were then studied at higher resolution using a full factorial DOE to obtain the globally optimized combination of parameter settings. The optimum combination of settings was then compared with our previously determined settings to quantify the degree of improvement in detection limit. The limit of detection for the optimized conditions was approximately 10 attomoles compared with 100 femtomoles for the previous settings, which corresponds to a four order of magnitude improvement in the detection limit of equine cytochrome c. PMID:22095501
Takin' It to the Hill: A Conversation with Jim Shanley
ERIC Educational Resources Information Center
Shreve, Bradley
2016-01-01
Jim Shanley (Assiniboine) served as president of Standing Rock Community College (now Sitting Bull College) and later Fort Peck Community College, where he remained for 28 years. He was also one of the American Indian Higher Education Consortium's (AIHEC) early leaders. At the age of 29, he was appointed as AIHEC's executive committee president…
Shekhar, R.; Karunasagar, D.; Ranjit, M.; Arunachalam, J.
2009-10-15
An open-to-air type electrolyte cathode discharge (ELCAD) has been developed with a new design. The present configuration leads to a stable plasma even at low flow rates (0.96 mL/min). Plasma fluctuations arising from the variations in the gap between solid anode and liquid cathode were eliminated by providing a V-groove to the liquid glass-capillary. Cathode (ground) connection is given to the solution at the V-groove itself. Interfaced to atomic emission spectrometry (AES), its analytical performance is evaluated. The optimized molarity of the solution is 0.2 M. The analytical response curves for Ca, Cu, Cd, Pb, Hg, Fe, and Zn demonstrated good linearity. The limit of detections of Ca, Cu, Cd, Pb, Hg, Fe, and Zn are determined to be 17, 11, 5, 45, 15, 28, and 3 ng mL{sup -1}. At an integration time of 0.3 s, the relative standard deviation (RSD) values of the acid blank solutions are found to be less than 10% for the elements Ca, Cu, Cd, Hg, Fe, and Zn and 18% for Pb. The method is applied for the determination of the elemental constituents in different matrix materials such as tuna fish (IAEA-350), oyster tissue (NIST SRM 1566a), and coal fly ash (CFA SRM 1633b). The obtained results are in good agreement with the certified values. The accuracy is found to be between 7% and 0.6% for major to trace levels of constituent elements and the precision between 11% and 0.6%. For the injection of 100 {mu} L of 200 ng mL{sup -1} mercury solution at the flow rate of 0.8 mL/min, the flow injection studies resulted in the relative standard deviation (RSD) of 8%, concentration detection limit of 10 ng/mL, and mass detection limit of 1 ng for mercury.
Matrix market: a web resource for test matrix collection
Boisvert, R.F.; Pozo, R.; Remington, K.; Barrett, R.F.; Dongarra, J.J. /
1996-05-30
We describe a repository of data for the testing of numerical algorithms and mathematical software for matrix computations. The repository is designed to accommodate both dense and sparse matrices, as well as software to generate matrices. It has been seeded with the well known Harwell-Boeing sparse matrix collection. The raw data files have been augmented with an integrated World Wide Web interface which describes the matrices in the collection quantitatively and visually, For example, each matrix has a Web page which details its attributes, graphically depicts its sparsity pattern, and provides access to the matrix itself in several formats. In addition, a search mechanism is included which allows retrieval of matrices based on a variety of attributes, such as type and size, as well as through free-text search in abstracts. The URL is http://math.nist.gov/MatrixMarket.
1990-06-01
Engineering and Te.1’ ical Manageent FOR THE COMMANDER JOHN C. MADDEN, Colonel, USAF S , Integrated Engineering Technical Managesent IF YOUR ADDRESS HAS...In those early years all aspects of engineering design were conducted under the umbrella of this one organization. The Division had under its control ...direct control of the engineering workforce. It now became more and more apparent that we needed to combine more and more elements of the total design
Making recombinant extracellular matrix proteins.
Ruggiero, Florence; Koch, Manuel
2008-05-01
A variety of approaches to understand extracellular matrix protein structure and function require production of recombinant proteins. Moreover, the expression of heterologous extracellular matrix proteins, in particular collagens, using the recombinant technology is of major interest to the biomedical industry. Although extracellular matrix proteins are large, modular and often multimeric, most of them have been successfully produced in various expression systems. This review provides important factors, including the design of the construct, the cloning strategies, the expression vectors, the transfection method and the host cell systems, to consider in choosing a reliable and cost-effective way to make recombinant extracellular matrix proteins. Advantages and drawbacks of each system have been appraised. Protocols that may ease efficient recombinant production of extracellular matrix are described. Emphasis is placed on the recombinant collagen production. Members of the collagen superfamily exhibit specific structural features and generally require complex post-translational modifications to retain full biological activity that make more arduous their recombinant production.
Fukunishi, Yoshifumi; Hojo, Shinichi; Nakamura, Haruki
2006-01-01
A new method has been developed to design a focused library based on available active compounds using protein-compound docking simulations. This method was applied to the design of a focused library for cytochrome P450 (CYP) ligands, not only to distinguish CYP ligands from other compounds but also to identify the putative ligands for a particular CYP. Principal component analysis (PCA) was applied to the protein-compound affinity matrix, which was obtained by thorough docking calculations between a large set of protein pockets and chemical compounds. Each compound was depicted as a point in the PCA space. Compounds that were close to the known active compounds were selected as candidate hit compounds. A machine-learning technique optimized the docking scores of the protein-compound affinity matrix to maximize the database enrichment of the known active compounds, providing an optimized focused library.
Hybrid matrix fiber composites
Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.
2003-07-15
Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites include two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.
NASA Technical Reports Server (NTRS)
Hyland, R. E.; Wohl, M. L.; Thompson, R. L.; Finnegan, P. M.
1972-01-01
The results are reported of a preliminary feasibility screening study for providing long-term solutions to the problems of handling and managing radioactive wastes by extraterrestrial transportation of the wastes. Matrix materials and containers are discussed along with payloads, costs, and destinations for candidate space vehicles. The conclusions reached are: (1) Matrix material such as spray melt can be used without exceeding temperature limits of the matrix. (2) The cost in mills per kw hr electric, of space disposal of fission products is 4, 5, and 28 mills per kw hr for earth escape, solar orbit, and solar escape, respectively. (3) A major factor effecting cost is the earth storage time. Based on a normal operating condition design for solar escape, a storage time of more than sixty years is required to make the space disposal charge less than 10% of the bus-bar electric cost. (4) Based on a 10 year earth storage without further processing, the number of shuttle launches required would exceed one per day.
Kazemikia, Kaveh; Bonabi, Fahimeh; Asadpoorchallo, Ali; Shokrzadeh, Majid
2015-02-01
In this work, an optimized pulsed magnetic field production apparatus is designed based on a RLC (Resistance/Self-inductance/Capacitance) discharge circuit. An algorithm for designing an optimum magnetic coil is presented. The coil is designed to work at room temperature. With a minor physical reinforcement, the magnetic flux density can be set up to 12 Tesla with 2 ms duration time. In our design process, the magnitude and the length of the magnetic pulse are the desired parameters. The magnetic field magnitude in the RLC circuit is maximized on the basis of the optimal design of the coil. The variables which are used in the optimization process are wire diameter and the number of coil layers. The coil design ensures the critically damped response of the RLC circuit. The electrical, mechanical, and thermal constraints are applied to the design process. A locus of probable magnetic flux density values versus wire diameter and coil layer is provided to locate the optimum coil parameters. Another locus of magnetic flux density values versus capacitance and initial voltage of the RLC circuit is extracted to locate the optimum circuit parameters. Finally, the application of high magnetic fields on carbon nanotube-PolyPyrrole (CNT-PPy) nano-composite is presented. Scanning probe microscopy technique is used to observe the orientation of CNTs after exposure to a magnetic field. The result shows alignment of CNTs in a 10.3 Tesla, 1.5 ms magnetic pulse.
Farooque, Mohammad; Yuh, Chao-Yi
1996-01-01
A carbonate fuel cell matrix comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles.
Matrix with Prescribed Eigenvectors
ERIC Educational Resources Information Center
Ahmad, Faiz
2011-01-01
It is a routine matter for undergraduates to find eigenvalues and eigenvectors of a given matrix. But the converse problem of finding a matrix with prescribed eigenvalues and eigenvectors is rarely discussed in elementary texts on linear algebra. This problem is related to the "spectral" decomposition of a matrix and has important technical…
Ghasemi Estahbanati, Ehsan; Omidkhah, Mohammadreza; Ebadi Amooghin, Abtin
2017-03-08
In this research, Pebax1657 as an organic phase and silver nanoparticles as an inorganic phase were used for preparation of binary mixed matrix membranes (MMMs). Silver nanoparticles as a filler could enter the polymer chains and enhance the gas permeability by increasing the fractional free volume of membranes. Afterward, ternary MMMs were fabricated by addition of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid, in order to have better polymer/filler adhesion and eliminate interfacial defects and nonselective voids. In addition, positively polarized silver nanoparticles in the presence of the IL could interact with PEO segment of the polymer and increase the CO2 affinity of membranes, which results in increasing the CO2/light gases permselectivity of MMMs. Gas permeation properties of MMMs were studied at a temperature of 35 °C and operating pressures from 2 to 10 bar. Moreover, fabricated membranes were characterized by fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). The analysis revealed that there is a proper adhesion between positively charged surface of nanoparticles and the polymer, and both filler and IL decrease the crystallinity of the membranes, which could enhance the polar gas transport properties. Gas permeation results showed significant enhancement in CO2 permeability (325 Barrer) for binary membrane (Pebax 1657/1%Ag) at 35 °C and 10 bar. Moreover, ternary MMM (Pebax 1657/0.5%Ag/50%IL) encountered significant increase in both permeability and selectivity in comparison with neat membrane. Indeed, the CO2 permeability increased from 110 Barrer to 180 (about 64%). Moreover, the related CO2/CH4 and CO2/N2 selectivities were increased from 20.8 to 61.0 (more than 193%) and from 78.6 to 187.5 (about 139%), respectively.
Anderson, Damon S; Kirchner, Marc; Kellogg, Mark; Kalish, Leslie A; Jeong, Jee-Yeong; Vanasse, Gary; Berliner, Nancy; Fleming, Mark D; Steen, Hanno
2011-11-01
Disorders of iron metabolism affect over a billion people worldwide. The circulating peptide hormone hepcidin, the central regulator of iron distribution in mammals, holds great diagnostic potential for an array of iron-associated disorders, including iron loading (β-thalassemia), iron overload (hereditary hemochromatosis), and iron deficiency diseases. We describe a novel high-throughput matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry assay for quantification of hepcidin in human plasma. This assay involves enrichment using a functionalized MALDI chip, a novel solvent-detergent precipitation buffer, and quantification using a stable isotope labeled internal standard. The linear range of hepcidin in plasma was 1-120 nM, with a low limit of quantification (LOQ) (1 nM), high accuracy (<15% relative error (RE)), and high precision (intraday average 5.52-18.48% coefficient of variation (CV) and interday 9.32-14.83% CV). The assay showed strong correlation with an established hepcidin immunoassay (Spearman; R(2) = 0.839 n = 93 ethylenediaminetetraacetic acid (EDTA) plasma). A collection of normal healthy pediatric samples (range 3.8-32.5 ng/mL; mean 12.9 ng/mL; n = 119) showed significant differences from an adult collection (range 1.8-48.7 ng/mL; mean 16.1 ng/mL; n = 95; P = 0.0096). We discuss these preliminary reference ranges and correlations with additional parameters in light of the utility and limitations of hepcidin measurements as a stand-alone diagnostic and as a tool for therapeutic intervention.
Wang, Zhongkai; Jiang, Feng; Zhang, Yaqiong; You, Yezi; Wang, Zhigang; Guan, Zhibin
2015-01-27
Human skin exhibits highly nonlinear elastic properties that are essential to its physiological functions. It is soft at low strain but stiff at high strain, thereby protecting internal organs and tissues from mechanical trauma. However, to date, the development of materials to mimic the unique mechanical properties of human skin is still a great challenge. Here we report a bioinspired design of nanostructured elastomers combining two abundant plant-based biopolymers, stiff cellulose and elastic polyisoprene (natural rubber), to mimic the mechanical properties of human skin. The nanostructured elastomers show highly nonlinear mechanical properties closely mimicking that of human skin. Importantly, the mechanical properties of these nanostructured elastomers can be tuned by adjusting cellulose content, providing the opportunity to synthesize materials that mimic the mechanical properties of different types of skins. Given the simplicity, efficiency, and tunability, this design may provide a promising strategy for creating artificial skin for both general mechanical and biomedical applications.
Khajeh, Mostafa; Ghanbari, Ahmad
2011-10-01
Essential oil of Salvia mirzayanii cultivated in Iran was obtained by microwave assisted extraction (MAE) procedures. The essential oil was analysed by capillary gas chromatography using flame ionisation and mass spectrometric detections. The effects of different parameters, such as microwave power, temperature, time and type of solvent on the MAE of Salvia mirzayanii oil were investigated. Results of the two-level fractional factorial design (2(4-1)) based on an analysis of variance demonstrated that only the power, temperature and type of solvent were statistically significant. Optimal conditions for the extraction of essential oils were obtained by using Box-Behnken design. For optimum recovery of essential oil the variables power, temperature and solvent values were 115 W, 50°C and 14 s, respectively. Under the optimised experimental conditions, the extraction yield of microwave assisted extraction was 11.2% (w/w).
Parce, J. Wallace; Bernatis, Paul; Dubrow, Robert; Freeman, William P.; Gamoras, Joel; Kan, Shihai; Meisel, Andreas; Qian, Baixin; Whiteford, Jeffery A.; Ziebarth, Jonathan
2010-01-12
Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.
Nara, Hiroshi; Sato, Kenjiro; Naito, Takako; Mototani, Hideyuki; Oki, Hideyuki; Yamamoto, Yoshio; Kuno, Haruhiko; Santou, Takashi; Kanzaki, Naoyuki; Terauchi, Jun; Uchikawa, Osamu; Kori, Masakuni
2014-11-13
Matrix metalloproteinase-13 (MMP-13) has been implicated to play a key role in the pathology of osteoarthritis. On the basis of X-ray crystallography, we designed a series of potent MMP-13 selective inhibitors optimized to occupy the distinct deep S1' pocket including an adjacent branch. Among them, carboxylic acid inhibitor 21k exhibited excellent potency and selectivity for MMP-13 over other MMPs. An effort to convert compound 21k to the mono sodium salt 38 was promising in all animal species studied. Moreover, no overt toxicity was observed in a preliminary repeat dose oral toxicity study of compound 21k in rats. A single oral dose of compound 38 significantly reduced degradation products (CTX-II) released from articular cartilage into the joint cavity in a rat MIA model in vivo. In this article, we report the discovery of highly potent, selective, and orally bioavailable MMP-13 inhibitors as well as their detailed structure-activity data.
Finding Nonoverlapping Substructures of a Sparse Matrix
Pinar, Ali; Vassilevska, Virginia
2005-08-11
Many applications of scientific computing rely on computations on sparse matrices. The design of efficient implementations of sparse matrix kernels is crucial for the overall efficiency of these applications. Due to the high compute-to-memory ratio and irregular memory access patterns, the performance of sparse matrix kernels is often far away from the peak performance on a modern processor. Alternative data structures have been proposed, which split the original matrix A into A{sub d} and A{sub s}, so that A{sub d} contains all dense blocks of a specified size in the matrix, and A{sub s} contains the remaining entries. This enables the use of dense matrix kernels on the entries of A{sub d} producing better memory performance. In this work, we study the problem of finding a maximum number of nonoverlapping dense blocks in a sparse matrix, which is previously not studied in the sparse matrix community. We show that the maximum nonoverlapping dense blocks problem is NP-complete by using a reduction from the maximum independent set problem on cubic planar graphs. We also propose a 2/3-approximation algorithm that runs in linear time in the number of nonzeros in the matrix. This extended abstract focuses on our results for 2x2 dense blocks. However we show that our results can be generalized to arbitrary sized dense blocks, and many other oriented substructures, which can be exploited to improve the memory performance of sparse matrix operations.
NASA Technical Reports Server (NTRS)
Noton, B. R. (Editor); Kreider, K. G.; Chamis, C. C.
1974-01-01
This volume discusses a vaety of applications of both low- and high-cost composite materials in a number of selected engineering fields. The text stresses the use of fiber-reinforced composites, along with interesting material systems used in the electrical and nuclear industries. As to technology transfer, a similarity is noted between many of the reasons responsible for the utilization of composites and those problems requiring urgent solution, such as mechanized fabrication processes and design for production. Features topics include road transportation, rail transportation, civil aircraft, space vehicles, builing industry, chemical plants, and appliances and equipment. The laminate orientation code devised by Air Force materials laboratory is included. Individual items are announced in this issue.
Chen, James M; Yeh, Li-An
2004-09-01
Collagenases are a highly specific class of enzymes. In their native states, collagenases cleave only native triple helical collagen molecules at a single peptide bond between Gly775-Leu776 for Type I collagen and Gly775-Ile776 for Type II collagen. The linear sequence of collagen is about 1050 amino acids in length, where three linear peptide sequences are required to form a triple helical collagen molecule. At present, there exist no crystallographic structures of collagenase bound to native triple helical collagen; nor has it been shown that collagenase recognizes the triple helical conformation of collagen. In our study, we have used an inhibitor design structure-activity based approach to show that collagenase recognizes and cleaves triple helical collagen conformations in preference to non-triple helical collagen conformations.
Fong, Jiunn N. C.; Yildiz, Fitnat H.
2015-01-01
Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enzymatic degradation of polysaccharides, proteins, and nucleic acids. In this chapter, we will review functions of matrix proteins in a selected set of microorganisms, studies of the matrix proteomes of Vibrio cholerae and Pseudomonas aeruginosa, and roles of outer membrane vesicles and of nucleoid-binding proteins in biofilm formation. PMID:26104709
Development, implementation, and test results on integrated optics switching matrix
NASA Technical Reports Server (NTRS)
Rutz, E.
1982-01-01
A small integrated optics switching matrix, which was developed, implemented, and tested, indicates high performance. The matrix serves as a model for the design of larger switching matrices. The larger integrated optics switching matrix should form the integral part of a switching center with high data rate throughput of up to 300 megabits per second. The switching matrix technique can accomplish the design goals of low crosstalk and low distortion. About 50 illustrations help explain and depict the many phases of the integrated optics switching matrix. Many equations used to explain and calculate the experimental data are also included.
Schlecht, Martin F.; Kassakian, John G.; Caloggero, Anthony J.; Rhodes, Bruce; Otten, David; Rasmussen, Neil
1982-01-01
An automatic switching matrix that includes an apertured matrix board containing a matrix of wires that can be interconnected at each aperture. Each aperture has associated therewith a conductive pin which, when fully inserted into the associated aperture, effects electrical connection between the wires within that particular aperture. Means is provided for automatically inserting the pins in a determined pattern and for removing all the pins to permit other interconnecting patterns.
Kidoaki, Satoru; Kwon, Il Kuen; Matsuda, Takehisa
2005-01-01
To design a mesoscopically ordered structure of the matrices and scaffolds composed of nano- and microscale fiber meshes for artificial and tissue-engineering devices, two new electrospinning techniques are proposed: multilayering electrospinning and mixing electrospinning. First, the following four kinds of component polymers were individually electrospun to determine the conditions for producing stable nano- and microfibers by optimizing the formulation parameters (solvent and polymer concentration) and operation parameters (voltage, air gap, and flow rate) for each polymer: (a) type I collagen, (b) styrenated gelatin (ST-gelatin), (c) segmented polyurethane (SPU), and (d) poly(ethylene oxide). A trilayered electrospun mesh, in which individual fiber meshes (type I collagen, ST-gelatin, and SPU) were deposited layer by layer, was formed by sequential electrospinning; this was clearly visualized by confocal laser scanning microscopy. The mixed electrospun-fiber mesh composed of SPU and PEO was prepared by simultaneous electrospinning on a stainless-steel mandrel with high-speed rotation and traverse movement. A bilayered tubular construct composed of a thick SPU microfiber mesh as an outer layer and a thin type I collagen nanofiber mesh as an inner layer was fabricated as a prototype scaffold of artificial grafts, and visualized by scanning electron microscopy.
Krishnamoorthy, Ganesan; Sehgal, Praveen Kumar; Mandal, Asit Baran; Sadulla, Sayeed
2013-04-01
This work discusses the preparation and characterization of collagen scaffold with presence of D-Lysine (Coll-D-Lys)-assisted 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinimide (NHS)-initiated cross linking. The mechanical strength, thermal and structural stability, resistance to biodegradation and cell viability of this scaffold was investigated. The results of the Coll-D-Lys-EDC/NHS scaffold also indicate an increase in the tensile strength (T(S)), percentage of elongation (% E), denaturation temperature (T(d)), and decrease the decomposition rate. Scanning electron microscopic (SEM) and atomic force microscopic (AFM) analyses revealed a well ordered with properly oriented and well-aligned structure of scaffold. The D-Lys stabilizes the scaffold against degradation by collagenase than L-Lys. The cell assay showed more than 98 ± 2% fibroblast viability (NIH 3T3) after 72 h of culture Coll-D-Lys-scaffold when compared with native Coll and Coll-L-Lys-scaffold. The proteolytic machinery is not well equipped to deal with Coll-D-Lys-scaffold than Coll-L-Lys-scaffold. Incorporating D-Lys in scaffold design has the potential to improve existing collagen stability and create new topologies inaccessible to homochiral molecules. This method may assist in the functionalization of the scaffold for regenerative applications.
Finding nonoverlapping substructures of a sparse matrix
Pinar, Ali; Vassilevska, Virginia
2004-08-09
Many applications of scientific computing rely on computations on sparse matrices, thus the design of efficient implementations of sparse matrix kernels is crucial for the overall efficiency of these applications. Due to the high compute-to-memory ratio and irregular memory access patterns, the performance of sparse matrix kernels is often far away from the peak performance on a modern processor. Alternative data structures have been proposed, which split the original matrix A into A{sub d} and A{sub s}, so that A{sub d} contains all dense blocks of a specified size in the matrix, and A{sub s} contains the remaining entries. This enables the use of dense matrix kernels on the entries of A{sub d} producing better memory performance. In this work, we study the problem of finding a maximum number of non overlapping rectangular dense blocks in a sparse matrix, which has not been studied in the sparse matrix community. We show that the maximum non overlapping dense blocks problem is NP-complete by using a reduction from the maximum independent set problem on cubic planar graphs. We also propose a 2/3-approximation algorithm for 2 times 2 blocks that runs in linear time in the number of nonzeros in the matrix. We discuss alternatives to rectangular blocks such as diagonal blocks and cross blocks and present complexity analysis and approximation algorithms.
Czerwinski, Michael; Spence, Jason R
2017-01-05
Recently in Nature, Gjorevski et al. (2016) describe a fully defined synthetic hydrogel that mimics the extracellular matrix to support in vitro growth of intestinal stem cells and organoids. The hydrogel allows exquisite control over the chemical and physical in vitro niche and enables identification of regulatory properties of the matrix.
Polymer Matrix Composite Material Oxygen Compatibility
NASA Technical Reports Server (NTRS)
Owens, Tom
2001-01-01
Carbon fiber/polymer matrix composite materials look promising as a material to construct liquid oxygen (LOX) tanks. Based on mechanical impact tests the risk will be greater than aluminum, however, the risk can probably be managed to an acceptable level. Proper tank design and operation can minimize risk. A risk assessment (hazard analysis) will be used to determine the overall acceptability for using polymer matrix composite materials.
Grassmann matrix quantum mechanics
Anninos, Dionysios; Denef, Frederik; Monten, Ruben
2016-04-21
We explore quantum mechanical theories whose fundamental degrees of freedom are rectangular matrices with Grassmann valued matrix elements. We study particular models where the low energy sector can be described in terms of a bosonic Hermitian matrix quantum mechanics. We describe the classical curved phase space that emerges in the low energy sector. The phase space lives on a compact Kähler manifold parameterized by a complex matrix, of the type discovered some time ago by Berezin. The emergence of a semiclassical bosonic matrix quantum mechanics at low energies requires that the original Grassmann matrices be in the long rectangular limit.more » In conclusion, we discuss possible holographic interpretations of such matrix models which, by construction, are endowed with a finite dimensional Hilbert space.« less
Grassmann matrix quantum mechanics
Anninos, Dionysios; Denef, Frederik; Monten, Ruben
2016-04-21
We explore quantum mechanical theories whose fundamental degrees of freedom are rectangular matrices with Grassmann valued matrix elements. We study particular models where the low energy sector can be described in terms of a bosonic Hermitian matrix quantum mechanics. We describe the classical curved phase space that emerges in the low energy sector. The phase space lives on a compact Kähler manifold parameterized by a complex matrix, of the type discovered some time ago by Berezin. The emergence of a semiclassical bosonic matrix quantum mechanics at low energies requires that the original Grassmann matrices be in the long rectangular limit. In conclusion, we discuss possible holographic interpretations of such matrix models which, by construction, are endowed with a finite dimensional Hilbert space.
Construction of the Dependence Matrix Based on the TRIZ Contradiction Matrix in OOD
NASA Astrophysics Data System (ADS)
Ma, Jianhong; Zhang, Quan; Wang, Yanling; Luo, Tao
In the Object-Oriented software design (OOD), design of the class and object, definition of the classes’ interface and inheritance levels and determination of dependent relations have a serious impact on the reusability and flexibility of the system. According to the concrete problems of design, how to select the right solution from the hundreds of the design schemas which has become the focus of attention of designers. After analyzing lots of software design schemas in practice and Object-Oriented design patterns, this paper constructs the dependence matrix of Object-Oriented software design filed, referring to contradiction matrix of TRIZ (Theory of Inventive Problem Solving) proposed by the former Soviet Union innovation master Altshuller. As the practice indicates, it provides a intuitive, common and standardized method for designers to choose the right design schema. Make research and communication more effectively, and also improve the software development efficiency and software quality.
ERIC Educational Resources Information Center
Online-Offline, 1998
1998-01-01
Provides an annotated bibliography of resources on this month's theme "Design" for K-8 language arts, art and architecture, music and dance, science, math, social studies, health, and physical education. Includes Web sites, CD-ROMs and software, videos, books, audiotapes, magazines, professional resources and classroom activities.…
ERIC Educational Resources Information Center
Buchanan, Richard; Cross, Nigel; Durling, David; Nelson, Harold; Owen, Charles; Valtonen, Anna; Boling, Elizabeth; Gibbons, Andrew; Visscher-Voerman, Irene
2013-01-01
Scholars representing the field of design were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Richard Buchanan, Nigel Cross, David Durling, Harold Nelson, Charles Owen, and Anna Valtonen. Scholars…
Martens, J.S.; Hietala, V.M.; Plut, T.A.
1995-01-03
The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N[times]M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise. 6 figures.
Martens, Jon S.; Hietala, Vincent M.; Plut, Thomas A.
1995-01-01
The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.
NASA Astrophysics Data System (ADS)
Morozov, A.
2012-08-01
Partition functions of eigenvalue matrix models possess a number of very different descriptions: as matrix integrals, as solutions to linear and nonlinear equations, as τ-functions of integrable hierarchies and as special-geometry prepotentials, as result of the action of W-operators and of various recursions on elementary input data, as gluing of certain elementary building blocks. All this explains the central role of such matrix models in modern mathematical physics: they provide the basic "special functions" to express the answers and relations between them, and they serve as a dream model of what one should try to achieve in any other field.
Design of Interfaces in Metal Matrix Composites
1993-02-15
powder particle refinement occurred and nanosize copper and titanium nitride particles were observed under the TENT. In addition, consolidation of the...nitride and Zirconium nitride possess r !hirIvelv hiigh 1\\ir,.ai c.’n. Ic, t[, high hardness and high melting point. Copper alloys dispersion hairdened h...each time materials and their surfaces ground to remove the to determine the extent and the mmnde phase f’,rmed oxide scale present. and then cleaned
The "Pesticide-exposure Matrix" was developed to help epidemiologists and other researchers identify the active ingredients to which people were likely exposed when their homes and gardens were treated for pests in past years.
Functional Polymer Matrix Fibers
2007-11-02
the carbon nanofibers led to the deterioration of the polymeric cellulose structure. Extensive research on the surface treatment of carbon nanofibers...1 November 2003 - 14-Mar-05 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER FA8655-03-1-3042 Functional Polymer Matrix Fibres 5b. GRANT NUMBER 5c. PROGRAM...MARYLABONE RD LONDON NWl 5TH PERFORMANCE REPORT Project title: Functional polymer matrix fibers Period of performance: 1 November 2003 - 31 October 2004
Optical coherency matrix tomography
Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.
2015-01-01
The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes. PMID:26478452
Matrix computations on mesh arrays
Moreno, J.H.
1989-01-01
This dissertation addresses the systematic derivation of mesh arrays for matrix computations, in particular realizing the algorithm-specific arrays and mapping algorithms onto class-specific arrays. A data-dependency graph-based transformational method is proposed in a design frame work consisting of two stages, namely algorithm regularization and derivation of arrays. The first stage derives the fully-parallel data-dependency graph (FPG) of an algorithm and transforms this graph into a three-dimensional one with unidirectional nearest-neighbor dependencies (a multi-mesh graph MMG). The second stage transforms the MMG into a two-dimensional G-graph, which is realized as an algorithm-specific array or mapped onto a class-specific array. This stage allows the incorporation of implementation restrictions and the evaluation of tradeoffs in properties of cells, as well as the derivation of arrays for fixed-size data and partitioned problems, while performing optimization of specific performance/cost measures. The proposed method is formalized by presenting a sufficient set of transformations and demonstrating the equivalence of graphs obtained from those transformations. Moreover, it is demonstrated that the MMG representation is always possible, due to the characteristics of the operators. The method has been applied to a collection of matrix algorithms, including matrix multiplication, convolution, matrix decompositions, transitive closure, the Faddeev algorithm, and BBA{sup {minus}1}. The examples show that, in addition to the features listed earlier, this method is easy to apply. Moreover, the method is compared with other techniques, concluding that it is advantageous because it meets evaluation criteria and produces more efficient arrays.
Optimal matrix approximants in structural identification
NASA Technical Reports Server (NTRS)
Beattie, C. A.; Smith, S. W.
1992-01-01
Problems of model correlation and system identification are central in the design, analysis, and control of large space structures. Of the numerous methods that have been proposed, many are based on finding minimal adjustments to a model matrix sufficient to introduce some desirable quality into that matrix. In this work, several of these methods are reviewed, placed in a modern framework, and linked to other previously known ideas in computational linear algebra and optimization. This new framework provides a point of departure for a number of new methods which are introduced here. Significant among these is a method for stiffness matrix adjustment which preserves the sparsity pattern of an original matrix, requires comparatively modest computational resources, and allows robust handling of noisy modal data. Numerical examples are included to illustrate the methods presented herein.
Generalized matrix inversion is not harder than matrix multiplication
NASA Astrophysics Data System (ADS)
Petkovic, Marko D.; Stanimirovic, Predrag S.
2009-08-01
Starting from the Strassen method for rapid matrix multiplication and inversion as well as from the recursive Cholesky factorization algorithm, we introduced a completely block recursive algorithm for generalized Cholesky factorization of a given symmetric, positive semi-definite matrix . We used the Strassen method for matrix inversion together with the recursive generalized Cholesky factorization method, and established an algorithm for computing generalized {2,3} and {2,4} inverses. Introduced algorithms are not harder than the matrix-matrix multiplication.
Extracellular matrix structure.
Theocharis, Achilleas D; Skandalis, Spyros S; Gialeli, Chrysostomi; Karamanos, Nikos K
2016-02-01
Extracellular matrix (ECM) is a non-cellular three-dimensional macromolecular network composed of collagens, proteoglycans/glycosaminoglycans, elastin, fibronectin, laminins, and several other glycoproteins. Matrix components bind each other as well as cell adhesion receptors forming a complex network into which cells reside in all tissues and organs. Cell surface receptors transduce signals into cells from ECM, which regulate diverse cellular functions, such as survival, growth, migration, and differentiation, and are vital for maintaining normal homeostasis. ECM is a highly dynamic structural network that continuously undergoes remodeling mediated by several matrix-degrading enzymes during normal and pathological conditions. Deregulation of ECM composition and structure is associated with the development and progression of several pathologic conditions. This article emphasizes in the complex ECM structure as to provide a better understanding of its dynamic structural and functional multipotency. Where relevant, the implication of the various families of ECM macromolecules in health and disease is also presented.
Pan, Feng; Kasiviswanathan, Shiva
2010-01-01
In the matrix interdiction problem, a real-valued matrix and an integer k is given. The objective is to remove k columns such that the sum over all rows of the maximum entry in each row is minimized. This combinatorial problem is closely related to bipartite network interdiction problem which can be applied to prioritize the border checkpoints in order to minimize the probability that an adversary can successfully cross the border. After introducing the matrix interdiction problem, we will prove the problem is NP-hard, and even NP-hard to approximate with an additive n{gamma} factor for a fixed constant {gamma}. We also present an algorithm for this problem that achieves a factor of (n-k) mUltiplicative approximation ratio.
Matrixed business support comparison study.
Parsons, Josh D.
2004-11-01
The Matrixed Business Support Comparison Study reviewed the current matrixed Chief Financial Officer (CFO) division staff models at Sandia National Laboratories. There were two primary drivers of this analysis: (1) the increasing number of financial staff matrixed to mission customers and (2) the desire to further understand the matrix process and the opportunities and challenges it creates.
Rheocasting Al Matrix Composites
NASA Astrophysics Data System (ADS)
Girot, F. A.; Albingre, L.; Quenisset, J. M.; Naslain, R.
1987-11-01
Aluminum alloy matrix composites reinforced by SiC short fibers (or whiskers) can be prepared by rheocasting, a process which consists of the incorporation and homogeneous distribution of the reinforcement by stirring within a semi-solid alloy. Using this technique, composites containing fiber volume fractions in the range of 8-15%, have been obtained for various fibers lengths (i.e., 1 mm, 3 mm and 6 mm for SiC fibers). This paper attempts to delineate the best compocasting conditions for aluminum matrix composites reinforced by short SiC (e.g Nicalon) or SiC whiskers (e.g., Tokamax) and characterize the resulting microstructures.
Density matrix perturbation theory.
Niklasson, Anders M N; Challacombe, Matt
2004-05-14
An orbital-free quantum perturbation theory is proposed. It gives the response of the density matrix upon variation of the Hamiltonian by quadratically convergent recursions based on perturbed projections. The technique allows treatment of embedded quantum subsystems with a computational cost scaling linearly with the size of the perturbed region, O(N(pert.)), and as O(1) with the total system size. The method allows efficient high order perturbation expansions, as demonstrated with an example involving a 10th order expansion. Density matrix analogs of Wigner's 2n+1 rule are also presented.
Inverter Matrix for the Clementine Mission
NASA Technical Reports Server (NTRS)
Buehler, M. G.; Blaes, B. R.; Tardio, G.; Soli, G. A.
1994-01-01
An inverter matrix test circuit was designed for the Clementine space mission and is built into the RRELAX (Radiation and Reliability Assurance Experiment). The objective is to develop a circuit that will allow the evaluation of the CMOS FETs using a lean data set in the noisy spacecraft environment.
Fracture toughness testing of polymer matrix composites
NASA Technical Reports Server (NTRS)
Grady, Joseph E.
1992-01-01
The experimental techniques and associated data analysis methods used to measure the resistance to interlaminar fracture, or 'fracture toughness', of polymer matrix composite materials are described. A review in the use of energy techniques to characterize fracture behavior in elastic solids is given. An overview is presented of the types of approaches employed in the design of delamination-resistant composite materials.
Matrix Embedded Organic Synthesis
NASA Astrophysics Data System (ADS)
Kamakolanu, U. G.; Freund, F. T.
2016-05-01
In the matrix of minerals such as olivine, a redox reaction of the low-z elements occurs. Oxygen is oxidized to the peroxy state while the low-Z-elements become chemically reduced. We assign them a formula [CxHyOzNiSj]n- and call them proto-organics.
NASA Astrophysics Data System (ADS)
Elliott, John
2012-09-01
As part of our 'toolkit' for analysing an extraterrestrial signal, the facility for calculating structural affinity to known phenomena must be part of our core capabilities. Without such a resource, we risk compromising our potential for detection and decipherment or at least causing significant delay in the process. To create such a repository for assessing structural affinity, all known systems (language parameters) need to be structurally analysed to 'place' their 'system' within a relational communication matrix. This will need to include all known variants of language structure, whether 'living' (in current use) or ancient; this must also include endeavours to incorporate yet undeciphered scripts and non-human communication, to provide as complete a picture as possible. In creating such a relational matrix, post-detection decipherment will be assisted by a structural 'map' that will have the potential for 'placing' an alien communication with its nearest known 'neighbour', to assist subsequent categorisation of basic parameters as a precursor to decipherment. 'Universal' attributes and behavioural characteristics of known communication structure will form a range of templates (Elliott, 2001 [1] and Elliott et al., 2002 [2]), to support and optimise our attempt at categorising and deciphering the content of an extraterrestrial signal. Detection of the hierarchical layers, which comprise intelligent, complex communication, will then form a matrix of calculations that will ultimately score affinity through a relational matrix of structural comparison. In this paper we develop the rationales and demonstrate functionality with initial test results.
Matrix product state renormalization
NASA Astrophysics Data System (ADS)
Bal, M.; Rams, M. M.; Zauner, V.; Haegeman, J.; Verstraete, F.
2016-11-01
The truncation or compression of the spectrum of Schmidt values is inherent to the matrix product state (MPS) approximation of one-dimensional quantum ground states. We provide a renormalization group picture by interpreting this compression as an application of Wilson's numerical renormalization group along the imaginary time direction appearing in the path integral representation of the state. The location of the physical index is considered as an impurity in the transfer matrix and static MPS correlation functions are reinterpreted as dynamical impurity correlations. Coarse-graining the transfer matrix is performed using a hybrid variational ansatz based on matrix product operators, combining ideas of MPS and the multiscale entanglement renormalization ansatz. Through numerical comparison with conventional MPS algorithms, we explicitly verify the impurity interpretation of MPS compression, as put forward by V. Zauner et al. [New J. Phys. 17, 053002 (2015), 10.1088/1367-2630/17/5/053002] for the transverse-field Ising model. Additionally, we motivate the conceptual usefulness of endowing MPS with an internal layered structure by studying restricted variational subspaces to describe elementary excitations on top of the ground state, which serves to elucidate a transparent renormalization group structure ingrained in MPS descriptions of ground states.
The Matrix of Care: A Heuristic for Assessment and Placement.
ERIC Educational Resources Information Center
Salamon, Michael J.
1986-01-01
A more productive approach to providing appropriate long-term care is to separate physical from psychosocial needs when performing functional assessment and to rearrange them into a matrix. By examining each need separately, and where needs overlap in the matrix, more direct assessment can be performed, and specified interventions can be designed.…
Bohn, Mark S.; Anselmo, Mark
2001-01-01
Computer simulation was used in the development of an inward-burning, radial matrix gas burner and heat pipe heat exchanger. The burner and exchanger can be used to heat a Stirling engine on cloudy days when a solar dish, the normal source of heat, cannot be used. Geometrical requirements of the application forced the use of the inward burning approach, which presents difficulty in achieving a good flow distribution and air/fuel mixing. The present invention solved the problem by providing a plenum with just the right properties, which include good flow distribution and good air/fuel mixing with minimum residence time. CFD simulations were also used to help design the primary heat exchanger needed for this application which includes a plurality of pins emanating from the heat pipe. The system uses multiple inlet ports, an extended distance from the fuel inlet to the burner matrix, flow divider vanes, and a ring-shaped, porous grid to obtain a high-temperature uniform-heat radial burner. Ideal applications include dish/Stirling engines, steam reforming of hydrocarbons, glass working, and any process requiring high temperature heating of the outside surface of a cylindrical surface.
Composite Matrix Experimental Combustor
1994-04-01
Preliminary (Macro) Combustor Design ............................. 28 4.1 Preliminary Design Study-Early Concept Combustion System ............. 28 4.2...provided in Appendix B. 4.1 PRELIMINARY DESIGN STUDY-EARLY CONCEPT COMBUSTION SYSTEM The preliminary design effort resulted in the selection of the early...overall flowpath. The concept I combustor is a compact, annular, reverse-flow design incorporating a single row of primary combustion air holes and a
NASA Astrophysics Data System (ADS)
Edelman, Alan; Rao, N. Raj
Random matrix theory is now a big subject with applications in many disciplines of science, engineering and finance. This article is a survey specifically oriented towards the needs and interests of a numerical analyst. This survey includes some original material not found anywhere else. We include the important mathematics which is a very modern development, as well as the computational software that is transforming the theory into useful practice.
NASA Astrophysics Data System (ADS)
Mortensen, Andreas; Llorca, Javier
2010-08-01
In metal matrix composites, a metal is combined with another, often nonmetallic, phase to produce a novel material having attractive engineering attributes of its own. A subject of much research in the 1980s and 1990s, this class of materials has, in the past decade, increased significantly in variety. Copper matrix composites, layered composites, high-conductivity composites, nanoscale composites, microcellular metals, and bio-derived composites have been added to a palette that, ten years ago, mostly comprised ceramic fiber- or particle-reinforced light metals together with some well-established engineering materials, such as WC-Co cermets. At the same time, research on composites such as particle-reinforced aluminum, aided by novel techniques such as large-cell 3-D finite element simulation or computed X-ray microtomography, has served as a potent vehicle for the elucidation of the mechanics of high-contrast two-phase elastoplastic materials, with implications that range well beyond metal matrix composites.
t matrix of metallic wire structures
Zhan, T. R. Chui, S. T.
2014-04-14
To study the electromagnetic resonance and scattering properties of complex structures of which metallic wire structures are constituents within multiple scattering theory, the t matrix of individual structures is needed. We have recently developed a rigorous and numerically efficient equivalent circuit theory in which retardation effects are taken into account for metallic wire structures. Here, we show how the t matrix can be calculated analytically within this theory. We illustrate our method with the example of split ring resonators. The density of states and cross sections for scattering and absorption are calculated, which are shown to be remarkably enhanced at resonant frequencies. The t matrix serves as the basic building block to evaluate the interaction of wire structures within the framework of multiple scattering theory. This will open the door to efficient design and optimization of assembly of wire structures.
Snapshot retinal imaging Mueller matrix polarimeter
NASA Astrophysics Data System (ADS)
Wang, Yifan; Kudenov, Michael; Kashani, Amir; Schwiegerling, Jim; Escuti, Michael
2015-09-01
Early diagnosis of glaucoma, which is a leading cause for visual impairment, is critical for successful treatment. It has been shown that Imaging polarimetry has advantages in early detection of structural changes in the retina. Here, we theoretically and experimentally present a snapshot Mueller Matrix Polarimeter fundus camera, which has the potential to record the polarization-altering characteristics of retina with a single snapshot. It is made by incorporating polarization gratings into a fundus camera design. Complete Mueller Matrix data sets can be obtained by analyzing the polarization fringes projected onto the image plane. In this paper, we describe the experimental implementation of the snapshot retinal imaging Mueller matrix polarimeter (SRIMMP), highlight issues related to calibration, and provide preliminary images acquired from the camera.
t matrix of metallic wire structures
NASA Astrophysics Data System (ADS)
Zhan, T. R.; Chui, S. T.
2014-04-01
To study the electromagnetic resonance and scattering properties of complex structures of which metallic wire structures are constituents within multiple scattering theory, the t matrix of individual structures is needed. We have recently developed a rigorous and numerically efficient equivalent circuit theory in which retardation effects are taken into account for metallic wire structures. Here, we show how the t matrix can be calculated analytically within this theory. We illustrate our method with the example of split ring resonators. The density of states and cross sections for scattering and absorption are calculated, which are shown to be remarkably enhanced at resonant frequencies. The t matrix serves as the basic building block to evaluate the interaction of wire structures within the framework of multiple scattering theory. This will open the door to efficient design and optimization of assembly of wire structures.
Pneumococcal MSCRAMM targeting of the extracellular matrix
Paterson, Gavin K.; Orihuela, Carlos J.
2010-01-01
The attachment of bacteria to host cells and tissues and their subsequent invasion and dissemination are key processes during disease pathogenesis. In this issue of Molecular Microbiology, Jensch and co-workers provide further molecular insight into these events during infection with the Gram-positive bacterium Streptococcus pneumoniae. Their characterization of PavB, a bacterial surface protein with orthologues in other streptococci, shows it to bind the extracellar matrix components fibronection and plasminogen by virtue of repetitive sequences designated Streptococcal Surface Repeats (SSURE). In mice, a pavB mutant showed reduced nasopharyngeal colonisation and was attenuated in a lung infection model. As discussed here in the context of the pneumococcus, the study of PavB highlights the central role during microbal pathogenesis of targetting the extracellular matrix by so-called MSCRAMMs (microbial surface components recognizing adhesive matrix molecules). PMID:20444102
Flexible matrix composite laminated disk/ring flywheel
NASA Technical Reports Server (NTRS)
Gupta, B. P.; Hannibal, A. J.
1984-01-01
An energy storage flywheel consisting of a quasi-isotropic composite disk overwrapped by a circumferentially wound ring made of carbon fiber and a elastometric matrix is proposed. Through analysis it was demonstrated that with an elastomeric matrix to relieve the radial stresses, a laminated disk/ring flywheel can be designed to store a least 80.3 Wh/kg or about 68% more than previous disk/ring designs. at the same time the simple construction is preserved.
An Innovative Carbonate Fuel Cell Matrix, Abstract #188
Hilmi, Abdelkader; Surendranath, Arun; Yuh, Chao-Yi
2015-05-28
The electrolyte matrix in direct carbonate fuel cell (DFC) is a microporous ceramic structure sandwiched between the electrodes to isolate the fuel from the oxidant, store electrolyte and facilitate ionic transport. FCE has advanced DFC electrolyte matrix over the years and demonstrated that the matrix meets the requirements for greater than 5 year life based on accelerated tests and field stack operations. However, development of advanced designs and materials that can further increase the performance and extend cell life will enable accelerated MCFC deployment. This paper will report the progress on the development of an unique and innovative matrix design that offers numerous benefits to the carbonate fuel cell performance and durability. In addition, this paper will also review parameters that affect matrix material stability and approaches to extend cell life.
On the Matrix Exponential Function
ERIC Educational Resources Information Center
Hou, Shui-Hung; Hou, Edwin; Pang, Wan-Kai
2006-01-01
A novel and simple formula for computing the matrix exponential function is presented. Specifically, it can be used to derive explicit formulas for the matrix exponential of a general matrix A satisfying p(A) = 0 for a polynomial p(s). It is ready for use in a classroom and suitable for both hand as well as symbolic computation.
The cellulose resource matrix.
Keijsers, Edwin R P; Yılmaz, Gülden; van Dam, Jan E G
2013-03-01
The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the
Review of fracture and fatigue in ceramic matrix composites
Birman, V.; Byrd, L.W.
2000-06-01
A review of recent developments and state-of-the-art in research and understanding of damage and fatigue of ceramic matrix composites is presented. Both laminated as well as woven configurations are considered. The work on the effects of high temperature on fracture and fatigue of ceramic matrix composites is emphasized, because these materials are usually designed to operate in hostile environments. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design and practical operational structures are outlined. This review article includes 317 references.
Supported Molecular Matrix Electrophoresis.
Matsuno, Yu-Ki; Kameyama, Akihiko
2015-01-01
Mucins are difficult to separate using conventional gel electrophoresis methods such as SDS-PAGE and agarose gel electrophoresis, owing to their large size and heterogeneity. On the other hand, cellulose acetate membrane electrophoresis can separate these molecules, but is not compatible with glycan analysis. Here, we describe a novel membrane electrophoresis technique, termed "supported molecular matrix electrophoresis" (SMME), in which a porous polyvinylidene difluoride (PVDF) membrane filter is used to achieve separation. This description includes the separation, visualization, and glycan analysis of mucins with the SMME technique.
Advanced Integration Matrix Education Outreach
NASA Technical Reports Server (NTRS)
Paul Heather L.
2004-01-01
The Advanced Integration Matrix (AIM) will design a ground-based test facility for developing revolutionary integrated systems for joint human-robotic missions in order to study and solve systems-level integration issues for exploration missions beyond Low Earth Orbit (LEO). This paper describes development plans for educational outreach activities related to technological and operational integration scenarios similar to the challenges that will be encountered through this project. The education outreach activities will provide hands-on, interactive exercises to allow students of all levels to experience design and operational challenges similar to what NASA deals with everyday in performing the integration of complex missions. These experiences will relate to and impact students everyday lives by demonstrating how their interests in science and engineering can develop into future careers, and reinforcing the concepts of teamwork and conflict resolution. Allowing students to experience and contribute to real-world development, research, and scientific studies of ground-based simulations for complex exploration missions will stimulate interest in the space program, and bring NASA's challenges to the student level. By enhancing existing educational programs and developing innovative activities and presentations, AIM will support NASA s endeavor to "inspire the next generation of explorers.. .as only NASA can."
Clinical implications of matrix metalloproteinases.
Mandal, Malay; Mandal, Amritlal; Das, Sudip; Chakraborti, Tapati; Sajal, Chakraborti
2003-10-01
Matrix metalloproteinases (MMPs) are a family of neutral proteinases that are important for normal development, wound healing, and a wide variety of pathological processes, including the spread of metastatic cancer cells, arthritic destruction of joints, atherosclerosis, pulmonary fibrosis, emphysema and neuroinflammation. In the central nervous system (CNS), MMPs have been shown to degrade components of the basal lamina, leading to disruption of the blood brain barrier and to contribute to the neuroinflammatory responses in many neurological diseases. Inhibition of MMPs have been shown to prevent progression of these diseases. Currently, certain MMP inhibitors have entered into clinical trials. A goal to the future should be to design selective synthetic inhibitors of MMPs that have minimum side effects. MMP inhibitors are designed in such a way that these can not only bind at the active site of the proteinases but also to have the characteristics to bind to other sites of MMPs which might be a promising route for therapy. To name a few: catechins, a component isolated from green tea; and Novastal, derived from extracts of shark cartilage are currently in clinical trials for the treatment of MMP-mediated diseases.
Luneburg lens and optical matrix algebra research
NASA Technical Reports Server (NTRS)
Wood, V. E.; Busch, J. R.; Verber, C. M.; Caulfield, H. J.
1984-01-01
Planar, as opposed to channelized, integrated optical circuits (IOCs) were stressed as the basis for computational devices. Both fully-parallel and systolic architectures are considered and the tradeoffs between the two device types are discussed. The Kalman filter approach is a most important computational method for many NASA problems. This approach to deriving a best-fit estimate for the state vector describing a large system leads to matrix sizes which are beyond the predicted capacities of planar IOCs. This problem is overcome by matrix partitioning, and several architectures for accomplishing this are described. The Luneburg lens work has involved development of lens design techniques, design of mask arrangements for producing lenses of desired shape, investigation of optical and chemical properties of arsenic trisulfide films, deposition of lenses both by thermal evaporation and by RF sputtering, optical testing of these lenses, modification of lens properties through ultraviolet irradiation, and comparison of measured lens properties with those expected from ray trace analyses.
Ceramic Matrix Composites for Rotorcraft Engines
NASA Technical Reports Server (NTRS)
Halbig, Michael C.
2011-01-01
Ceramic matrix composite (CMC) components are being developed for turbine engine applications. Compared to metallic components, the CMC components offer benefits of higher temperature capability and less cooling requirements which correlates to improved efficiency and reduced emissions. This presentation discusses a technology develop effort for overcoming challenges in fabricating a CMC vane for the high pressure turbine. The areas of technology development include small component fabrication, ceramic joining and integration, material and component testing and characterization, and design and analysis of concept components.
Ceramic matrix and resin matrix composites: A comparison
NASA Technical Reports Server (NTRS)
Hurwitz, Frances I.
1987-01-01
The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.
Takin: An open-source software for experiment planning, visualisation, and data analysis
NASA Astrophysics Data System (ADS)
Weber, Tobias; Georgii, Robert; Böni, Peter
Due to their non-trivial resolution function, measurements on triple-axis spectrometers require extra care from the experimentalist in order to obtain optimal results and to avoid unwanted spurious artefacts. We present a free and open-source software system that aims to ease many of the tasks encountered during the planning phase, in the execution and in data treatment of experiments performed on neutron triple-axis spectrometers. The software is currently in use and has been successfully tested at the MLZ, but can be configured to work with other triple-axis instruments and instrument control systems.
Mixed Mode Matrix Multiplication
Meng-Shiou Wu; Srinivas Aluru; Ricky A. Kendall
2004-09-30
In modern clustering environments where the memory hierarchy has many layers (distributed memory, shared memory layer, cache,...), an important question is how to fully utilize all available resources and identify the most dominant layer in certain computations. When combining algorithms on all layers together, what would be the best method to get the best performance out of all the resources we have? Mixed mode programming model that uses thread programming on the shared memory layer and message passing programming on the distributed memory layer is a method that many researchers are using to utilize the memory resources. In this paper, they take an algorithmic approach that uses matrix multiplication as a tool to show how cache algorithms affect the performance of both shared memory and distributed memory algorithms. They show that with good underlying cache algorithm, overall performance is stable. When underlying cache algorithm is bad, superlinear speedup may occur, and an increasing number of threads may also improve performance.
Matrix membranes and integrability
Zachos, C.; Fairlie, D.; Curtright, T.
1997-06-01
This is a pedagogical digest of results reported in Curtright, Fairlie, {ampersand} Zachos 1997, and an explicit implementation of Euler`s construction for the solution of the Poisson Bracket dual Nahm equation. But it does not cover 9 and 10-dimensional systems, and subsequent progress on them Fairlie 1997. Cubic interactions are considered in 3 and 7 space dimensions, respectively, for bosonic membranes in Poisson Bracket form. Their symmetries and vacuum configurations are explored. Their associated first order equations are transformed to Nahm`s equations, and are hence seen to be integrable, for the 3-dimensional case, by virtue of the explicit Lax pair provided. Most constructions introduced also apply to matrix commutator or Moyal Bracket analogs.
Hyaluronan: A Matrix Component
NASA Astrophysics Data System (ADS)
Rügheimer, Louise
2008-09-01
The glucosaminoglycan hyaluronan is a key component of the extracellular matrix. It is a large, negatively charged molecule that can act as an ion exchange reservoir for positive ions. Hyaluronan is involved in renomedullary water handling through its water-binding capacity. In the renal medulla, the main source for hyaluronan production is the renomedullary interstitial cells. Hyaluronan synthases are found in the inner part of the plasma membrane and polymerize hyaluronan chains which are extruded into the extracellular space. Hyaluronidases are a family of enzymes involved in the degradation of hyaluronan. They have a wide range of properties, including differences in size, inhibitor sensitivities, catalytic mechanisms, substrate specificities and pH optima.
Hastings, Matthew B
2009-01-01
We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.
NASA Technical Reports Server (NTRS)
1976-01-01
Design concepts for a 1000 mw thermal stationary power plant employing the UF6 fueled gas core breeder reactor are examined. Three design combinations-gaseous UF6 core with a solid matrix blanket, gaseous UF6 core with a liquid blanket, and gaseous UF6 core with a circulating blanket were considered. Results show the gaseous UF6 core with a circulating blanket was best suited to the power plant concept.
Lectures on Matrix Field Theory
NASA Astrophysics Data System (ADS)
Ydri, Badis
The subject of matrix field theory involves matrix models, noncommutative geometry, fuzzy physics and noncommutative field theory and their interplay. In these lectures, a lot of emphasis is placed on the matrix formulation of noncommutative and fuzzy spaces, and on the non-perturbative treatment of the corresponding field theories. In particular, the phase structure of noncommutative $\\phi^4$ theory is treated in great detail, and an introduction to noncommutative gauge theory is given.
Fabrication and characterization of AZ91/CNT magnesium matrix composites
NASA Astrophysics Data System (ADS)
Park, Yong-Ha; Park, Yong-Ho; Park, Ik-Min; Oak, Jeong-jung; Kimura, Hisamichi; Cho, Kyung-Mox
2008-12-01
Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this study, we report light-weight, high strength heat resistant magnesium matrix composites. Microstructural study and tensile test were performed for the squeeze infiltrated magnesium matrix composites. The wear properties were characterized and the possibility for the application to automotive power train and engine parts was investigated. It was found that the squeeze infiltration technique is a proper method to fabricate magnesium matrix composites reducing casting defects such as pores and matrix/reinforcement interface separation etc. Improved tensile and mechanical properties were obtained with CNT reinforcing magnesium alloys
Systematic errors for a Mueller matrix dual rotating compensator ellipsometer.
Broch, Laurent; En Naciri, Aotmane; Johann, Luc
2008-06-09
The characterization of anisotropic materials and complex systems by ellipsometry has pushed the design of instruments to require the measurement of the full reflection Mueller matrix of the sample with a great precision. Therefore Mueller matrix ellipsometers have emerged over the past twenty years. The values of some coefficients of the matrix can be very small and errors due to noise or systematic errors can induce distored analysis. We present a detailed characterization of the systematic errors for a Mueller Matrix Ellipsometer in the dual-rotating compensator configuration. Starting from a general formalism, we derive explicit first-order expressions for the errors on all the coefficients of the Mueller matrix of the sample. The errors caused by inaccuracy of the azimuthal arrangement of the optical components and residual ellipticity introduced by imperfect optical elements are shown. A new method based on a four-zone averaging measurement is proposed to vanish the systematic errors.
Channeled partial Mueller matrix polarimetry
NASA Astrophysics Data System (ADS)
Alenin, Andrey S.; Tyo, J. S.
2015-09-01
In prior work,1,2 we introduced methods to treat channeled systems in a way that is similar to Data Reduction Method (DRM), by focusing attention on the Fourier content of the measurement conditions. Introduction of Q enabled us to more readily extract the performance of the system and thereby optimize it to obtain reconstruction with the least noise. The analysis tools developed for that exercise can be expanded to be applicable to partial Mueller Matrix Polarimeters (pMMPs), which were a topic of prior discussion as well. In this treatment, we combine the principles involved in both of those research trajectories and identify a set of channeled pMMP families. As a result, the measurement structure of such systems is completely known and the design of a channeled pMMP intended for any given task becomes a search over a finite set of possibilities, with the additional channel rotation allowing for a more desirable Mueller element mixing.
Ceramic matrix composite article and process of fabricating a ceramic matrix composite article
Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert
2016-01-12
A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.
Smart structure control in matrix second order form
NASA Astrophysics Data System (ADS)
Diwekar, Anjali M.; Yedavalli, Rama K.
1995-05-01
Matrix second order systems arise in a variety of structural dynamics and control problems. The analysis and design of such systems is traditionally done in frequency domain or in time domain (state space framework). The formulation of the control design problem in matrix second order form (i.e., configuration space framework) has many advantages over first order state space form. In this paper, a novel approach for designing a stabilizing controller in a second-order model of piezoelectrically controlled flexible beam is proposed.
Smart structure control in matrix second-order form
NASA Astrophysics Data System (ADS)
Diwekar, Anjali M.; Yedavalli, Rama K.
1996-08-01
Matrix second-order systems arise in a variety of structural dynamics and control problems. The analysis and design of such systems is traditionally done in the frequency domain or in the time domain (state space framework). The formulation of the control design problem in matrix second-order form (i.e. configuration space framework) has many advantages over first-order state-space form. In this paper, a novel approach for designing a stabilizing controller in a second-order model of a piezoelectrically controlled flexible beam is proposed.
Hybridized polymer matrix composites
NASA Technical Reports Server (NTRS)
House, E. E.; Hoggatt, J. T.; Symonds, W. A.
1980-01-01
The extent to which graphite fibers are released from resin matrix composites that are exposed to fire and impact conditions was determined. Laboratory simulations of those conditions that could exist in the event of an aircraft crash and burn situation were evaluated. The effectiveness of various hybridizing concepts in preventing this release of graphite fibers were also evaluated. The baseline (i.e., unhybridized) laminates examined were prepared from commercially available graphite/epoxy, graphite/polyimide, and graphite/phenolic materials. Hybridizing concepts investigated included resin fillers, laminate coatings, resin blending, and mechanical interlocking of the graphite reinforcement. The baseline and hybridized laminates' mechanical properties, before and after isothermal and humidity aging, were also compared. It was found that a small amount of graphite fiber was released from the graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that several hybrid concepts eliminated this fiber release. Isothermal and humidity aging did not appear to alter the fiber release tendencies.
Calkins, Noel C.
1991-01-01
An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.
NASA supercritical airfoils: A matrix of family-related airfoils
NASA Technical Reports Server (NTRS)
Harris, Charles D.
1990-01-01
The NASA supercritical airfoil development program is summarized in a chronological fashion. Some of the airfoil design guidelines are discussed, and coordinates of a matrix of family related supercritical airfoils ranging from thicknesses of 2 to 18 percent and over a design lift coefficient range from 0 to 1.0 are presented.
Cell–material interactions on biphasic polyurethane matrix
Dicesare, Patrick; Fox, Wade M.; Hill, Michael J.; Krishnan, G. Rajesh; Yang, Shuying; Sarkar, Debanjan
2013-01-01
Cell–matrix interaction is a key regulator for controlling stem cell fate in regenerative tissue engineering. These interactions are induced and controlled by the nanoscale features of extracellular matrix and are mimicked on synthetic matrices to control cell structure and functions. Recent studies have shown that nanostructured matrices can modulate stem cell behavior and exert specific role in tissue regeneration. In this study, we have demonstrated that nanostructured phase morphology of synthetic matrix can control adhesion, proliferation, organization and migration of human mesenchymal stem cells (MSCs). Nanostructured biodegradable polyurethanes (PU) with segmental composition exhibit biphasic morphology at nanoscale dimensions and can control cellular features of MSCs. Biodegradable PU with polyester soft segment and hard segment composed of aliphatic diisocyanates and dipeptide chain extender were designed to examine the effect polyurethane phase morphology. By altering the polyurethane composition, morphological architecture of PU was modulated and its effect was examined on MSC. Results show that MSCs can sense the nanoscale morphology of biphasic polyurethane matrix to exhibit distinct cellular features and, thus, signifies the relevance of matrix phase morphology. The role of nanostructured phases of a synthetic matrix in controlling cell–matrix interaction provides important insights for regulation of cell behavior on synthetic matrix and, therefore, is an important tool for engineering tissue regeneration. PMID:23255285
Uncovering Community Structures with Initialized Bayesian Nonnegative Matrix Factorization
Tang, Xianchao; Xu, Tao; Feng, Xia; Yang, Guoqing
2014-01-01
Uncovering community structures is important for understanding networks. Currently, several nonnegative matrix factorization algorithms have been proposed for discovering community structure in complex networks. However, these algorithms exhibit some drawbacks, such as unstable results and inefficient running times. In view of the problems, a novel approach that utilizes an initialized Bayesian nonnegative matrix factorization model for determining community membership is proposed. First, based on singular value decomposition, we obtain simple initialized matrix factorizations from approximate decompositions of the complex network’s adjacency matrix. Then, within a few iterations, the final matrix factorizations are achieved by the Bayesian nonnegative matrix factorization method with the initialized matrix factorizations. Thus, the network’s community structure can be determined by judging the classification of nodes with a final matrix factor. Experimental results show that the proposed method is highly accurate and offers competitive performance to that of the state-of-the-art methods even though it is not designed for the purpose of modularity maximization. PMID:25268494
ERIC Educational Resources Information Center
Jairam, Dharmananda; Kiewra, Kenneth A.; Kauffman, Douglas F.; Zhao, Ruomeng
2012-01-01
This study investigated how best to study a matrix. Fifty-three participants studied a matrix topically (1 column at a time), categorically (1 row at a time), or in a unified way (all at once). Results revealed that categorical and unified study produced higher: (a) performance on relationship and fact tests, (b) study material satisfaction, and…
Matrix Methods to Analytic Geometry.
ERIC Educational Resources Information Center
Bandy, C.
1982-01-01
The use of basis matrix methods to rotate axes is detailed. It is felt that persons who have need to rotate axes often will find that the matrix method saves considerable work. One drawback is that most students first learning to rotate axes will not yet have studied linear algebra. (MP)
Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix
Dr. Ronald Baney
2008-12-15
The objective of this project has been to identify a process for separating transuranic species from silicon carbide (SiC). Silicon carbide has become one of the prime candidates for the matrix in inert matrix fuels, (IMF) being designed to reduce plutonium inventories and the long half-lives actinides through transmutation since complete reaction is not practical it become necessary to separate the non-transmuted materials from the silicon carbide matrix for ultimate reprocessing. This work reports a method for that required process.l
Optical implementation of the Hopfield neural network with matrix gratings
NASA Astrophysics Data System (ADS)
Yeh, Sheng L.; Lo, Rong C.; Shi, Cha Y.
2004-02-01
We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.
Rolling Element Bearing Stiffness Matrix Determination (Presentation)
Guo, Y.; Parker, R.
2014-01-01
Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.
Micromechanics for ceramic matrix composites
NASA Technical Reports Server (NTRS)
Murthy, P. L. N.; Chamis, C. C.
1991-01-01
The fiber substructuring concepts and the micromechanics equations that are embedded in the Ceramic Matrix Composite Analyzer (CEMCAN) computer code are described as well as the code itself, its current features and capabilities, and some examples to demonstrate the code's versatility. The methodology is equally applicable to metal matrix and polymer matrix composites. The prediction of ply mechanical and thermal properties agree very well with the existing models in the Integrated Composite Analyzer and the Ceramic Matrix Composite Analyzer, lending credence to the fiber substructuring approach. Fiber substructuring can capture greater local detail than conventional unit-cell-based micromechanical theories. It offers promise in simulating complex aspects of micromechanics in ceramic matrix composites.
Graphite matrix materials for nuclear waste isolation
Morgan, W.C.
1981-06-01
At low temperatures, graphites are chemically inert to all but the strongest oxidizing agents. The raw materials from which artificial graphites are produced are plentiful and inexpensive. Morover, the physical properties of artificial graphites can be varied over a very wide range by the choice of raw materials and manufacturing processes. Manufacturing processes are reviewed herein, with primary emphasis on those processes which might be used to produce a graphite matrix for the waste forms. The approach, recommended herein, involves the low-temperature compaction of a finely ground powder produced from graphitized petroleum coke. The resultant compacts should have fairly good strength, low permeability to both liquids and gases, and anisotropic physical properties. In particular, the anisotropy of the thermal expansion coefficients and the thermal conductivity should be advantageous for this application. With two possible exceptions, the graphite matrix appears to be superior to the metal alloy matrices which have been recommended in prior studies. The two possible exceptions are the requirements on strength and permeability; both requirements will be strongly influenced by the containment design, including the choice of materials and the waste form, of the multibarrier package. Various methods for increasing the strength, and for decreasing the permeability of the matrix, are reviewed and discussed in the sections in Incorporation of Other Materials and Elimination of Porosity. However, it would be premature to recommend a particular process until the overall multi-barrier design is better defined. It is recommended that increased emphasis be placed on further development of the low-temperature compacted graphite matrix concept.
NASA Astrophysics Data System (ADS)
Horne, Richard B.; Kersten, Tobias; Glauert, Sarah A.; Meredith, Nigel P.; Boscher, Daniel; Sicard, Angelica; Maget, Vincent
2013-04-01
Whistler mode chorus waves play a major role in the loss and acceleration of electrons in the Earth's radiation belts. While high time resolution satellite data show that these waves are highly structured in frequency and time, at present their effects on the electron distribution can only be assessed on a global scale by using quasi-linear diffusion theory. Here we present new quasi-linear diffusion coefficients for upper and lower band chorus waves for use in global radiation belt models. Using data from DE 1 CRRES, Cluster 1, Double Star TC1 and THEMIS, we have constructed a database of wave properties and used this to construct new diffusion coefficients for L* = 1.5 to 10 in steps of 0.5, 10 latitude bins between 0o and 60o ,8 bins in MLT and 5 levels of geomagnetic activity as measured by Kp. We find that the peak frequency of lower band chorus is close to 0.2 fce, which is lower than that used in previous models. The combined upper and lower band chorus diffusion shows structure that should result in an energy dependent pitch angle anisotropy, particularly between 1 keV and 100 keV. The diffusion rates suggest that wave-particle interactions should still be very important outside geostationary orbit, out to at least L* = 8. We find significant energy diffusion near 1 keV near the loss cone, consistent with wave growth. By including the new chorus diffusion matrix into the BAS radiation belt (BRB) model we compare the effects on the evolution of the radiation belts against previous models.
NASA Astrophysics Data System (ADS)
Hung, Ming-Chin; Hsiao, Hsia-Tsai; Lin, Wei-Ting; Tu, Chun-Hao; Chang, Jiun-Jye; Chen, Po-Lun
2011-03-01
The present five masks bottom gate and staggered amorphous silicon (a-Si) thin-film transistor (TFT) process flow is not suitable for indium-gallium-zinc-oxide (IGZO) TFT because of its vulnerability to post etching process during the source/drain pattern. Bottom gate and coplanar IGZO TFTs were made feasible through the reverse of second (channel layer) and third (source/drain electrodes) masks process flow to avoid etching damage problem. Besides, the post IGZO nitrous oxygen (N2O) plasma treatment was employed to improve the stress instability. On the basis of secondary ion mass spectrometry (SIMS) and X-ray spectroscopy (XPS) results, it is believed that the post N2O plasma treatment passivates the interface states and converts the inhomogeneous and low quality IGZO to the homogeneous and high quality IGZO. In the end, a 5-in. IGZO active-matrix liquid crystal display was demonstrated via five masks bottom gate and coplanar TFT configuration.
Hybridized polymer matrix composites
NASA Technical Reports Server (NTRS)
London, A.
1981-01-01
Design approaches and materials are described from which are fabricated pyrostatic graphite/epoxy (Gr/Ep) laminates that show improved retention of graphite particulates when subjected to burning. Sixteen hybridized plus two standard Gr/Ep laminates were designed, fabricated, and tested in an effort to eliminate the release of carbon (graphite) fiber particles from burned/burning, mechanically disturbed samples. The term pyrostatic is defined as meaning mechanically intact in the presence of fire. Graphite particulate retentive laminates were constructed whose constituent materials, cost of fabrication, and physical and mechanical properties were not significantly different from existing Gr/Ep composites. All but one laminate (a Celion graphite/bis-maleimide polyimide) were based on an off-the-shelf Gr/Ep, the AS-1/3501-5A system. Of the 16 candidates studied, four thin (10-ply) and four thick (50-ply) hybridized composites are recommended.
Electronic nose with an air sensor matrix for detecting beef freshness
Technology Transfer Automated Retrieval System (TEKTRAN)
The design of an electronic nose includes the design of a matrix of chemical sensors such as gas sensors, and development of a pattern-recognition algorithm. The sensor matrix sniffs the vapor from a sample and provides a set of measurements. The pattern-recognizer compares the pattern of the meas...
NASA Astrophysics Data System (ADS)
Oehlmann, Dietmar; Ohlmann, Odile M.; Danzebrink, Hans U.
2005-04-01
perform this exchange, as a matrix, understood as source, of new ideas.
Why regenerative medicine needs an extracellular matrix.
Prestwich, Glenn D; Healy, Kevin E
2015-01-01
Regenerative medicine is now coming of age. Many attempts at cell therapy have failed to show significant efficacy, and the umbrella term 'stem cell therapy' is perceived in some quarters as hype or just expensive and unnecessary medical tourism. Here we present a short editorial in three parts. First, we examine the importance of using a semisynthetic extracellular matrix (ECM) mimetic, or sECM, to deliver and retain therapeutic cells at the site of administration. Second, we describe one approach in which biophysical and biochemical properties are tailored to each tissue type, which we call "design for optimal functionality." Third, we describe an alternative approach to sECM design and implementation, called "design for simplicity," in which a deconstructed, minimalist sECM is employed and biology is allowed to perform the customization in situ. We opine that an sECM, whether minimal or instructive, is an essential contributor to improve the outcomes of cell-based therapies.
Solid oxide fuel cell matrix and modules
Riley, B.
1988-04-22
Porous refractory ceramic blocks arranged in an abutting, stacked configuration and forming a three dimensional array provide a support structure and coupling means for a plurality of solid oxide fuel cells (SOFCs). The stack of ceramic blocks is self-supporting, with a plurality of such stacked arrays forming a matrix enclosed in an insulating refractory brick structure having an outer steel layer. The necessary connections for air, fuel, burnt gas, and anode and cathode connections are provided through the brick and steel outer shell. The ceramic blocks are so designed with respect to the strings of modules that by simple and logical design the strings could be replaced by hot reloading if one should fail. The hot reloading concept has not been included in any previous designs. 11 figs.
Matrix cracking in brittle-matrix composites with tailored interfaces
Danchaivijit, S.; Chao, L.Y.; Shetty, D.K.
1995-10-01
Matrix cracking from controlled through cracks with bridging filaments was studied in a model unidirectional composite of SiC filaments in an epoxy-bonded alumina matrix. An unbonded, frictional interface was produced by moderating the curing shrinkage of the epoxy with the alumina filler and coating the filaments with a releasing agent. Uniaxial tension test specimens (2.5 x 25 x 125 mm) with filament-bridged through cracks were fabricated by a novel two-step casting technique involving casting, precracking and joining of cracked and uncracked sections. Distinct matrix-cracking stresses, corresponding to the extension of the filament-bridged cracks, were measured in uniaxial tension tests using a high-sensitivity extensometer. The crack-length dependence of the matrix-cracking stress was found to be in good agreement with the prediction of a fracture-mechanics analysis that employed a new crack-closure force-crack-opening displacement relation in the calculation of the stress intensity for fiber-bridged cracks. The prediction was based on independent experimental measurements of the matrix fracture toughness (K{sub cm}), the interfacial sliding friction stress ({tau}) and the residual stress in the matrix ({sigma}{sub m}{sup I}). The matrix-cracking stress for crack lengths (2a) greater than 3 mm was independent of the crack length and agreed with the prediction of the steady-state theory of Budiansky, Hutchinson and Evans. Tests on specimens without the deliberately introduced cracks indicated a matrix-cracking stress significantly higher than the steady-state stress.
New pole placement algorithm - Polynomial matrix approach
NASA Technical Reports Server (NTRS)
Shafai, B.; Keel, L. H.
1990-01-01
A simple and direct pole-placement algorithm is introduced for dynamical systems having a block companion matrix A. The algorithm utilizes well-established properties of matrix polynomials. Pole placement is achieved by appropriately assigning coefficient matrices of the corresponding matrix polynomial. This involves only matrix additions and multiplications without requiring matrix inversion. A numerical example is given for the purpose of illustration.
Matrix Fourth-Complex Variables
NASA Astrophysics Data System (ADS)
Dimiev, Stancho; Marinov, Marin S.; Stoev, Peter
2009-11-01
In the paper we consider quasi-cyclic hyper-complex variables which are naturally related to the partial differential equations with complex variables. In fact, we develop a matrix 4×4 generalization of the classical bicomplex numbers [1], [2]. We recall that a matrix 2×2 isomorphic type treatment of the classical bicomplex numbers was developed in [3]. Here we develop a matrix 4×4 generalization of the bicomplex numbers including some improvement of the papers [3] and [4]. Let us remark that a deep generalization of the considered ideas was sketch in [5] before us.
Mechanotransduction and extracellular matrix homeostasis
Humphrey, Jay D.; Dufresne, Eric R.; Schwartz, Martin A.
2015-01-01
Preface Soft connective tissues at steady state are yet dynamic; resident cells continually read environmental cues and respond to promote homeostasis, including maintenance of the mechanical properties of the extracellular matrix that are fundamental to cellular and tissue health. The mechanosensing process involves assessment of the mechanics of the matrix by the cells through integrins and the actomyosin cytoskeleton, and is followed by a mechano-regulation process that includes the deposition, rearrangement, or removal of matrix to maintain overall form and function. Progress toward understanding the molecular, cellular, and tissue scale effects that promote mechanical homeostasis has helped identify key questions for future research. PMID:25355505
Genotype imputation via matrix completion
Chi, Eric C.; Zhou, Hua; Chen, Gary K.; Del Vecchyo, Diego Ortega; Lange, Kenneth
2013-01-01
Most current genotype imputation methods are model-based and computationally intensive, taking days to impute one chromosome pair on 1000 people. We describe an efficient genotype imputation method based on matrix completion. Our matrix completion method is implemented in MATLAB and tested on real data from HapMap 3, simulated pedigree data, and simulated low-coverage sequencing data derived from the 1000 Genomes Project. Compared with leading imputation programs, the matrix completion algorithm embodied in our program MENDEL-IMPUTE achieves comparable imputation accuracy while reducing run times significantly. Implementation in a lower-level language such as Fortran or C is apt to further improve computational efficiency. PMID:23233546
High temperature polymer matrix composites
NASA Technical Reports Server (NTRS)
Serafini, Tito T. (Editor)
1987-01-01
These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) Characterization; (4) environmental effects; and (5) applications.
High Temperature Polymer Matrix Composites
NASA Technical Reports Server (NTRS)
1985-01-01
These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) characterization; (4) environmental effects; and (5) applications.
Chan, Garnet Kin-Lic; Keselman, Anna; Nakatani, Naoki; Li, Zhendong; White, Steven R
2016-07-07
Current descriptions of the ab initio density matrix renormalization group (DMRG) algorithm use two superficially different languages: an older language of the renormalization group and renormalized operators, and a more recent language of matrix product states and matrix product operators. The same algorithm can appear dramatically different when written in the two different vocabularies. In this work, we carefully describe the translation between the two languages in several contexts. First, we describe how to efficiently implement the ab initio DMRG sweep using a matrix product operator based code, and the equivalence to the original renormalized operator implementation. Next we describe how to implement the general matrix product operator/matrix product state algebra within a pure renormalized operator-based DMRG code. Finally, we discuss two improvements of the ab initio DMRG sweep algorithm motivated by matrix product operator language: Hamiltonian compression, and a sum over operators representation that allows for perfect computational parallelism. The connections and correspondences described here serve to link the future developments with the past and are important in the efficient implementation of continuing advances in ab initio DMRG and related algorithms.
NASA Astrophysics Data System (ADS)
Chan, Garnet Kin-Lic; Keselman, Anna; Nakatani, Naoki; Li, Zhendong; White, Steven R.
2016-07-01
Current descriptions of the ab initio density matrix renormalization group (DMRG) algorithm use two superficially different languages: an older language of the renormalization group and renormalized operators, and a more recent language of matrix product states and matrix product operators. The same algorithm can appear dramatically different when written in the two different vocabularies. In this work, we carefully describe the translation between the two languages in several contexts. First, we describe how to efficiently implement the ab initio DMRG sweep using a matrix product operator based code, and the equivalence to the original renormalized operator implementation. Next we describe how to implement the general matrix product operator/matrix product state algebra within a pure renormalized operator-based DMRG code. Finally, we discuss two improvements of the ab initio DMRG sweep algorithm motivated by matrix product operator language: Hamiltonian compression, and a sum over operators representation that allows for perfect computational parallelism. The connections and correspondences described here serve to link the future developments with the past and are important in the efficient implementation of continuing advances in ab initio DMRG and related algorithms.
Interfacial reactions in titanium-matrix composites
Yang, J.M.; Jeng, S.M. )
1989-11-01
A study of the interfacial reaction characteristics of SiC fiber-reinforced titanium aluminide and disordered titanium alloy composites has determined that the matrix alloy compositions affect the microstructure and the distribution of the reaction products, as well as the growth kinetics of the reaction zones. The interfacial reaction products in the ordered titanium aluminide composite are more complicated than those in the disordered titanium-alloy composite. The activation energy of the interfacial reaction in the ordered titanium aluminide composite is also higher than that in the disordered titanium alloy composite. Designing an optimum interface is necessary to enhance the reliability and service life at elevated temperatures. 16 refs.
Metal Matrix Composite Materials for Aerospace Applications
NASA Technical Reports Server (NTRS)
Bhat, Biliyar N.; Jones, C. S. (Technical Monitor)
2001-01-01
Metal matrix composites (MMC) are attractive materials for aerospace applications because of their high specific strength, high specific stiffness, and lower thermal expansion coefficient. They are affordable since complex parts can be produced by low cost casting process. As a result there are many commercial and Department of Defense applications of MMCs today. This seminar will give an overview of MMCs and their state-of-the-art technology assessment. Topics to be covered are types of MMCs, fabrication methods, product forms, applications, and material selection issues for design and manufacture. Some examples of current and future aerospace applications will also be presented and discussed.
Extracellular matrix and wound healing.
Maquart, F X; Monboisse, J C
2014-04-01
Extracellular matrix has been known for a long time as an architectural support for the tissues. Many recent data, however, have shown that extracellular matrix macromolecules (collagens, elastin, glycosaminoglycans, proteoglycans and connective tissue glycoproteins) are able to regulate many important cell functions, such as proliferation, migration, protein synthesis or degradation, apoptosis, etc., making them able to play an important role in the wound repair process. Not only the intact macromolecules but some of their specific domains, that we called "Matrikines", are also able to regulate many cell activities. In this article, we will summarize main findings showing the effects of extracellular matrix macromolecules and matrikines on connective tissue and epithelial cells, particularly in skin, and their potential implication in the wound healing process. These examples show that extracellular matrix macromolecules or some of their specific domains may play a major role in wound healing. Better knowledge of these interactions may suggest new therapeutic targets in wound healing defects.
Matrix quantum mechanics from qubits
NASA Astrophysics Data System (ADS)
Hartnoll, Sean A.; Huijse, Liza; Mazenc, Edward A.
2017-01-01
We introduce a transverse field Ising model with order N 2 spins interacting via a nonlocal quartic interaction. The model has an O( N, ℤ), hyperoctahedral, symmetry. We show that the large N partition function admits a saddle point in which the symmetry is enhanced to O( N). We further demonstrate that this `matrix saddle' correctly computes large N observables at weak and strong coupling. The matrix saddle undergoes a continuous quantum phase transition at intermediate couplings. At the transition the matrix eigenvalue distribution becomes disconnected. The critical excitations are described by large N matrix quantum mechanics. At the critical point, the low energy excitations are waves propagating in an emergent 1 + 1 dimensional spacetime.
Stochastic determination of matrix determinants.
Dorn, Sebastian; Ensslin, Torsten A
2015-07-01
Matrix determinants play an important role in data analysis, in particular when Gaussian processes are involved. Due to currently exploding data volumes, linear operations-matrices-acting on the data are often not accessible directly but are only represented indirectly in form of a computer routine. Such a routine implements the transformation a data vector undergoes under matrix multiplication. While efficient probing routines to estimate a matrix's diagonal or trace, based solely on such computationally affordable matrix-vector multiplications, are well known and frequently used in signal inference, there is no stochastic estimate for its determinant. We introduce a probing method for the logarithm of a determinant of a linear operator. Our method rests upon a reformulation of the log-determinant by an integral representation and the transformation of the involved terms into stochastic expressions. This stochastic determinant determination enables large-size applications in Bayesian inference, in particular evidence calculations, model comparison, and posterior determination.
Molybdenum disilicide alloy matrix composite
Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott
1990-01-01
Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.
Staggered chiral random matrix theory
Osborn, James C.
2011-02-01
We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.
Molybdenum disilicide alloy matrix composite
Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott
1991-01-01
Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.
Molybdenum disilicide alloy matrix composite
Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.
1991-12-03
Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.
Algorithmic deformation of matrix factorisations
NASA Astrophysics Data System (ADS)
Carqueville, Nils; Dowdy, Laura; Recknagel, Andreas
2012-04-01
Branes and defects in topological Landau-Ginzburg models are described by matrix factorisations. We revisit the problem of deforming them and discuss various deformation methods as well as their relations. We have implemented these algorithms and apply them to several examples. Apart from explicit results in concrete cases, this leads to a novel way to generate new matrix factorisations via nilpotent substitutions, and to criteria whether boundary obstructions can be lifted by bulk deformations.
Universal Keplerian state transition matrix
NASA Technical Reports Server (NTRS)
Shepperd, S. W.
1985-01-01
A completely general method for computing the Keplerian state transition matrix in terms of Goodyear's universal variables is presented. This includes a new scheme for solving Kepler's problem which is a necessary first step to computing the transition matrix. The Kepler problem is solved in terms of a new independent variable requiring the evaluation of only one transcendental function. Furthermore, this transcendental function may be conveniently evaluated by means of a Gaussian continued fraction.
Mueller-Jones Matrix measurement in material identification
NASA Astrophysics Data System (ADS)
Xu, Jiang; Qian, Weixian; Wang, Xiao
2016-09-01
The uniformity of lattice arrangement plays an important role in industrial processing, science and technology studies and environmental pollution detection. However, there are very little papers to study surface structure by depolarization characteristics. In order to improve the efficiency and accuracy of material identification system by polarization technology, we developed a new method to decompose the Mueller matrix, we studied the mechanism of the scattering of electromagnetic wave, and analyzed the relationship between the characteristics of depolarization and mechanism of scattering. We used the Jones Matrix and Mueller Matrix to set up the physical model, and decomposed the Mueller-Jones Matrix by the characteristics of polarization, then got the depolarization coefficients (ωd) of the surfaces of the samples. By using this theory, we deduced the relation formula of Mueller matrix, Mueller-Jones matrix and Isotropic-Depolarizer matrix. Based on the polarized characteristics of the samples, we analyzed design method of material identification system and gave the results of the experimental test. Finally, we applied the theory of Fresnel formulas to verify the theoretical model. From the results, we found that the depolarization coefficients of the samples' surfaces were related to the scattering, and in the whole measurement process, the depolarization coefficients of the samples were far different; the method could easily to distinguish the metal and nonmetal, and more quickly to analyze the surface roughness of the samples. Therefore, the depolarization technology had a great application value, and the paper had very important significance on the development of surface structure study.
Automated acoustic matrix deposition for MALDI sample preparation.
Aerni, Hans-Rudolf; Cornett, Dale S; Caprioli, Richard M
2006-02-01
Novel high-throughput sample preparation strategies for MALDI imaging mass spectrometry (IMS) and profiling are presented. An acoustic reagent multispotter was developed to provide improved reproducibility for depositing matrix onto a sample surface, for example, such as a tissue section. The unique design of the acoustic droplet ejector and its optimization for depositing matrix solution are discussed. Since it does not contain a capillary or nozzle for fluid ejection, issues with clogging of these orifices are avoided. Automated matrix deposition provides better control of conditions affecting protein extraction and matrix crystallization with the ability to deposit matrix accurately onto small surface features. For tissue sections, matrix spots of 180-200 microm in diameter were obtained and a procedure is described for generating coordinate files readable by a mass spectrometer to permit automated profile acquisition. Mass spectral quality and reproducibility was found to be better than that obtained with manual pipet spotting. The instrument can also deposit matrix spots in a dense array pattern so that, after analysis in a mass spectrometer, two-dimensional ion images may be constructed. Example ion images from a mouse brain are presented.
Recycling of aluminum matrix composites
Nishida, Yoshinori; Izawa, Norihisa; Kuramasu, Yukio
1999-03-01
Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was separated from the alumina short fiber-reinforced composites. The separation ratio of the matrix from the SiC whisker-reinforced 6061 alloy composite was low and about 20 vol pct. The separation mechanism was discussed thermodynamically using interface free energies. Since the flux/fiber interface energy is smaller than the aluminum/fiber interface energy, the replacement of aluminum with fluxes in composites takes place easily. Gases released by the decomposition of fluxes act an important role in pushing out the molten matrix metal from the composite. The role was confirmed by the great amount cavity formed in the composite after the matrix metal flowed out.
Carbonate fuel cell matrix strengthening
Yuh, C.Y.; Haung, C.M.; Johnsen, R.
1995-12-31
The present baseline electrolyte matrix is a porous ceramic powder bed impregnated with alkali carbonate electrolyte. The matrix provides both ionic conduction and gas sealing. During fuel cell stack operation, the matrix experiences both mechanical and thermal stresses. Different mechanical characteristics of active and wet seal areas generate stress. Thermal stress is generated by nonuniform temperature distribution and thermal cycling. A carbonate fuel cell generally may experience planned and unplanned thermal cycles between 650 C and room temperature during its 40,000h life. During the cycling, the electrolyte matrix expands and contracts at a different rate from other cell components. Furthermore, the change in electrolyte volume associated with freezing/melting may generate additional thermal stress. Strengthening of the matrix may be beneficial for longer-term stability of the carbonate fuel cell with respect to repeated thermal cycling. Several promising strengtheners with improved chemical and mechanical stabilities were identified. Fibers provide the highest strengthening effect, followed by particulates. Matrix fabrication technique was successfully modified for uniformly incorporating the advanced strengtheners, maintaining the desired aspect ratio. Enhanced gas sealing demonstrated using the advanced matrices.
Hybridized polymer matrix composites
NASA Technical Reports Server (NTRS)
Henshaw, J.
1983-01-01
Methods of improving the fire resistance of graphite epoxy composite laminates were investigated with the objective of reducing the volume of loose graphite fibers disseminated into the airstream as the result of a high intensity aircraft fuel fire. Improvements were sought by modifying the standard graphite epoxy systems without significantly negating their structural effectiveness. The modifications consisted primarily of an addition of a third constituent material such as glass fibers, glass flakes, carbon black in a glassy resin. These additions were designed to encourage coalescense of the graphite fibers and thereby reduce their aerodynamic float characteristics. A total of 38 fire tests were conducted on thin (1.0 mm) and thick (6.0 mm) hybrid panels.
Experimental investigations on mechanical behavior of aluminium metal matrix composites
NASA Astrophysics Data System (ADS)
Rajesh, A. M.; Kaleemulla, Mohammed
2016-09-01
Today we are widely using aluminium based metal matrix composite for structural, aerospace, marine and automobile applications for its light weight, high strength and low production cost. The purpose of designing metal matrix composite is to add the desirable attributes of metals and ceramics to the base metal. In this study we developed aluminium metal matrix hybrid composite by reinforced Aluminium7075 alloy with silicon carbide (SiC) and aluminium oxide (alumina) by method of stir casting. This technique is less expensive and very effective. The Hardness test and Wear test were performed on the specimens which are prepared by stir casting techniques. The result reveals that the addition of silicon carbide and alumina particles in aluminium matrix improves the mechanical properties.
The transfer matrix approach to circular graphene quantum dots
NASA Astrophysics Data System (ADS)
Chau Nguyen, H.; Nguyen, Nhung T. T.; Nguyen, V. Lien
2016-07-01
We adapt the transfer matrix (T-matrix) method originally designed for one-dimensional quantum mechanical problems to solve the circularly symmetric two-dimensional problem of graphene quantum dots. Similar to one-dimensional problems, we show that the generalized T-matrix contains rich information about the physical properties of these quantum dots. In particular, it is shown that the spectral equations for bound states as well as quasi-bound states of a circular graphene quantum dot and related quantities such as the local density of states and the scattering coefficients are all expressed exactly in terms of the T-matrix for the radial confinement potential. As an example, we use the developed formalism to analyse physical aspects of a graphene quantum dot induced by a trapezoidal radial potential. Among the obtained results, it is in particular suggested that the thermal fluctuations and electrostatic disorders may appear as an obstacle to controlling the valley polarization of Dirac electrons.
Modeling the Stress Strain Behavior of Woven Ceramic Matrix Composites
NASA Technical Reports Server (NTRS)
Morscher, Gregory N.
2006-01-01
Woven SiC fiber reinforced SiC matrix composites represent one of the most mature composite systems to date. Future components fabricated out of these woven ceramic matrix composites are expected to vary in shape, curvature, architecture, and thickness. The design of future components using woven ceramic matrix composites necessitates a modeling approach that can account for these variations which are physically controlled by local constituent contents and architecture. Research over the years supported primarily by NASA Glenn Research Center has led to the development of simple mechanistic-based models that can describe the entire stress-strain curve for composite systems fabricated with chemical vapor infiltrated matrices and melt-infiltrated matrices for a wide range of constituent content and architecture. Several examples will be presented that demonstrate the approach to modeling which incorporates a thorough understanding of the stress-dependent matrix cracking properties of the composite system.
Matrix-assisted diffusion-ordered spectroscopy: choosing a matrix.
Gramosa, Nilce V; Ricardo, Nágila M S P; Adams, Ralph W; Morris, Gareth A; Nilsson, Mathias
2016-06-07
Diffusion-ordered spectroscopy (DOSY) is an important technique for separating the NMR signals of the components in a mixture, and relies on differences in diffusion coefficient. Standard DOSY experiments therefore struggle when the components of a mixture are of similar size, and hence diffuse at similar rates. Fortunately, the diffusion coefficients of solutes can be manipulated by changing the matrix in which they diffuse, using matrix components that interact differentially with them, a technique known as matrix-assisted DOSY. In the present investigation, we evaluate the performance of a number of new, previously used, and mixed matrices with an informative test mixture: the three positional isomers of dihydroxybenzene. The aim of this work is to present the matrix-assisted DOSY user with information about the potential utility of a set of matrices (and combinations of matrices), including ionic and non-ionic surfactants, complexing agents, polymers, and mixed solvents. A variety of matrices improved the diffusion resolution of the signals of the test system, with the best separation achieved by mixed micelles of sodium dodecyl sulfate and cetyl trimethylammonium bromide. The use of mixed matrices offers great potential for the analyst to tailor the matrix to a particular sample under study. © 2016 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons, Ltd.
2007-12-01
SME is an emergency response planning and exercise design and management software. SME implements an innovative approach of hosting its data in a customized Windows SharPoint Services (WSS) 3.0 site, and uses a Microsoft Win Forms technology as front-end to access the backend SharePoint list data as a client-server application. The utilization of WSS 3.0 allowed for a light weight application with the pwoer or project, data, document and user management tools that can link with everyday application such as Microsoft Office products, especially Outlook. The WinForms front-end application programmatically accesses the SharePoint List data through the exposed SharePoint Web Services application programming inerface (API). The SharePoint environment includes customized Web Parts that programmatically create new SharePoint sites with custom lists. The application also takes advantage of AJAX and Silverlight technologies to create a richer user experience for the SharePoint users.
Bandwidth and Noise in Spatiotemporally Modulated Mueller Matrix Polarimeters
NASA Astrophysics Data System (ADS)
Vaughn, Israel Jacob
Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is
The Astrobiology Matrix and the "Drake Matrix" in Education
NASA Technical Reports Server (NTRS)
Mizser, A.; Kereszturi, A.
2003-01-01
We organized astrobiology lectures in the Eotvos Lorand University of Sciences and the Polaris Observatory in 2002. We present here the "Drake matrix" for the comparison of the astrobiological potential of different bodies [1], and astrobiology matrix for the visualization of the interdisciplinary connections between different fields of astrobiology. Conclusion: In Hungary it is difficult to integrate astrobiology in the education system but the great advantage is that it can connect different scientific fields and improve the view of students. We would like to get in contact with persons and organizations who already have experience in the education of astrobiology.
Cooled Ceramic Matrix Composite Propulsion Structures Demonstrated
NASA Technical Reports Server (NTRS)
Jaskowiak, Martha H.; Dickens, Kevin W.
2005-01-01
NASA's Next Generation Launch Technology (NGLT) Program has successfully demonstrated cooled ceramic matrix composite (CMC) technology in a scramjet engine test. This demonstration represented the world s largest cooled nonmetallic matrix composite panel fabricated for a scramjet engine and the first cooled nonmetallic composite to be tested in a scramjet facility. Lightweight, high-temperature, actively cooled structures have been identified as a key technology for enabling reliable and low-cost space access. Tradeoff studies have shown this to be the case for a variety of launch platforms, including rockets and hypersonic cruise vehicles. Actively cooled carbon and CMC structures may meet high-performance goals at significantly lower weight, while improving safety by operating with a higher margin between the design temperature and material upper-use temperature. Studies have shown that using actively cooled CMCs can reduce the weight of the cooled flow-path component from 4.5 to 1.6 lb/sq ft and the weight of the propulsion system s cooled surface area by more than 50 percent. This weight savings enables advanced concepts, increased payload, and increased range. The ability of the cooled CMC flow-path components to operate over 1000 F hotter than the state-of-the-art metallic concept adds system design flexibility to space-access vehicle concepts. Other potential system-level benefits include smaller fuel pumps, lower part count, lower cost, and increased operating margin.
Relativistic Dipole Matrix Element Zeros
NASA Astrophysics Data System (ADS)
Lajohn, L. A.; Pratt, R. H.
2002-05-01
There is a special class of relativistic high energy dipole matrix element zeros (RZ), whose positions with respect to photon energy ω , only depend on the bound state l quantum number according to ω^0=mc^2/(l_b+1) (independent of primary quantum number n, nuclear charge Z, central potential V and dipole retardation). These RZ only occur in (n,l_b,j_b)arrow (ɛ , l_b+1,j_b) transitions such as ns_1/2arrow ɛ p_1/2; np_3/2arrow ɛ d_3/2: nd_5/2arrow ɛ f_5/2 etc. The nonrelativistic limit of these matrix elements can be established explicitly in the Coulomb case. Within the general matrix element formalism (such as that in [1]); when |κ | is substituted for γ in analytic expressions for matrix elements, the zeros remain, but ω^0 now becomes dependent on n and Z. When the reduction to nonrelativistic form is completed by application of the low energy approximation ω mc^2 mc^2, the zeros disappear. This nonzero behavior was noted in nonrelativistic dipole Coulomb matrix elements by Fano and Cooper [2] and later proven by Oh and Pratt[3]. (J. H. Scofield, Phys. Rev. A 40), 3054 (1989 (U. Fano and J. W. Cooper, Rev. Mod. Phys. 40), 441 (1968). (D. Oh and R. H. Pratt, Phys. Rev. A 34), 2486 (1986); 37, 1524 (1988); 45, 1583 (1992).
Matrix factorizations and elliptic fibrations
NASA Astrophysics Data System (ADS)
Omer, Harun
2016-09-01
I use matrix factorizations to describe branes at simple singularities of elliptic fibrations. Each node of the corresponding Dynkin diagrams of the ADE-type singularities is associated with one indecomposable matrix factorization which can be deformed into one or more factorizations of lower rank. Branes with internal fluxes arise naturally as bound states of the indecomposable factorizations. Describing branes in such a way avoids the need to resolve singularities. This paper looks at gauge group breaking from E8 fibers down to SU (5) fibers due to the relevance of such fibrations for local F-theory GUT models. A purpose of this paper is to understand how the deformations of the singularity are understood in terms of its matrix factorizations. By systematically factorizing the elliptic fiber equation, this paper discusses geometries which are relevant for building semi-realistic local models. In the process it becomes evident that breaking patterns which are identical at the level of the Kodaira type of the fibers can be inequivalent at the level of matrix factorizations. Therefore the matrix factorization picture supplements information which the conventional less detailed descriptions lack.
Active Matrix OLED Test Report
NASA Technical Reports Server (NTRS)
Salazar, George
2013-01-01
This report focuses on the limited environmental testing of the AMOLED display performed as an engineering evaluation by The NASA Johnson Space Center (JSC)-specifically. EMI. Thermal Vac, and radiation tests. The AMOLED display is an active-matrix Organic Light Emitting Diode (OLED) technology. The testing provided an initial understanding of the technology and its suitability for space applications. Relative to light emitting diode (LED) displays or liquid crystal displays (LCDs), AMOLED displays provide a superior viewing experience even though they are much lighter and smaller, produce higher contrast ratio and richer colors, and require less power to operate than LCDs. However, AMOLED technology has not been demonstrated in a space environment. Therefore, some risks with the technology must be addressed before they can be seriously considered for human spaceflight. The environmental tests provided preliminary performance data on the ability of the display technology to handle some of the simulated induced space/spacecraft environments that an AMOLED display will see during a spacecraft certification test program. This engineering evaluation is part of a Space Act Agreement (SM) between The NASA/JSC and Honeywell International (HI) as a collaborative effort to evaluate the potential use of AMOLED technology for future human spaceflight missions- both government-led and commercial. Under this SM, HI is responsible for doing optical performance evaluation, as well as temperature and touch screen studies. The NASA/JSC is responsible for performing environmental testing comprised of EMI, Thermal Vac, and radiation tests. Additionally, as part of the testing, limited optical data was acquired to assess performance as the display was subjected to the induced environments. The NASA will benefit from this engineering evaluation by understanding AMOLED suitability for future use in space as well as becoming a smarter buyer (or developer) of the technology. HI benefits
Noncommutative spaces from matrix models
NASA Astrophysics Data System (ADS)
Lu, Lei
Noncommutative (NC) spaces commonly arise as solutions to matrix model equations of motion. They are natural generalizations of the ordinary commutative spacetime. Such spaces may provide insights into physics close to the Planck scale, where quantum gravity becomes relevant. Although there has been much research in the literature, aspects of these NC spaces need further investigation. In this dissertation, we focus on properties of NC spaces in several different contexts. In particular, we study exact NC spaces which result from solutions to matrix model equations of motion. These spaces are associated with finite-dimensional Lie-algebras. More specifically, they are two-dimensional fuzzy spaces that arise from a three-dimensional Yang-Mills type matrix model, four-dimensional tensor-product fuzzy spaces from a tensorial matrix model, and Snyder algebra from a five-dimensional tensorial matrix model. In the first part of this dissertation, we study two-dimensional NC solutions to matrix equations of motion of extended IKKT-type matrix models in three-space-time dimensions. Perturbations around the NC solutions lead to NC field theories living on a two-dimensional space-time. The commutative limit of the solutions are smooth manifolds which can be associated with closed, open and static two-dimensional cosmologies. One particular solution is a Lorentzian fuzzy sphere, which leads to essentially a fuzzy sphere in the Minkowski space-time. In the commutative limit, this solution leads to an induced metric that does not have a fixed signature, and have a non-constant negative scalar curvature, along with singularities at two fixed latitudes. The singularities are absent in the matrix solution which provides a toy model for resolving the singularities of General relativity. We also discussed the two-dimensional fuzzy de Sitter space-time, which has irreducible representations of su(1,1) Lie-algebra in terms of principal, complementary and discrete series. Field
Matrix model approach to cosmology
NASA Astrophysics Data System (ADS)
Chaney, A.; Lu, Lei; Stern, A.
2016-03-01
We perform a systematic search for rotationally invariant cosmological solutions to toy matrix models. These models correspond to the bosonic sector of Lorentzian Ishibashi, Kawai, Kitazawa and Tsuchiya (IKKT)-type matrix models in dimensions d less than ten, specifically d =3 and d =5 . After taking a continuum (or commutative) limit they yield d -1 dimensional Poisson manifolds. The manifolds have a Lorentzian induced metric which can be associated with closed, open, or static space-times. For d =3 , we obtain recursion relations from which it is possible to generate rotationally invariant matrix solutions which yield open universes in the continuum limit. Specific examples of matrix solutions have also been found which are associated with closed and static two-dimensional space-times in the continuum limit. The solutions provide for a resolution of cosmological singularities, at least within the context of the toy matrix models. The commutative limit reveals other desirable features, such as a solution describing a smooth transition from an initial inflation to a noninflationary era. Many of the d =3 solutions have analogues in higher dimensions. The case of d =5 , in particular, has the potential for yielding realistic four-dimensional cosmologies in the continuum limit. We find four-dimensional de Sitter d S4 or anti-de Sitter AdS4 solutions when a totally antisymmetric term is included in the matrix action. A nontrivial Poisson structure is attached to these manifolds which represents the lowest order effect of noncommutativity. For the case of AdS4 , we find one particular limit where the lowest order noncommutativity vanishes at the boundary, but not in the interior.
Matrix cracking initiation stress in fiber-reinforced ceramic matrix composites
NASA Astrophysics Data System (ADS)
Kangutkar, Pramod Balkrishna
1991-05-01
One of the important design parameters in CMC's in the Matrix Cracking Initiation Stress (MCIS) which corresponds to the stress at which first matrix cracks are observed. Above the MCIS, the fibers will be exposed to the oxidizing environment which may degrade the mechanical property of the fibers and thus of the composite. In this thesis a systematic study to explore the effects of matrix toughness and inherent strength, fiber diameter, stiffness and volume fraction, temperature and interfacial bonding on the MCIS was carried out. Composites were fabricated using three different matrices--borosilicate glass, aluminosilicate glass and polycrystalline zirconium silicate (or zircon), and two different reinforcing fibers--an SiC monofilament (140 micron diameter) and an SiC yarn (16 micron diameter). In-situ observations during 3-point bend test inside the SEM indicate that matrix cracking is a local phenomenon and occurs first in the matrix between widest spaced fibers. In all composites the MCIS was found to increase with fiber additions and scaled with the monolithic strength. The relative increase in MCIS over the monolithic strength with fiber volume fraction, however, was found to depend strongly on the a(sub 0)/S ratio, where a(sub 0) is the inherent unreinforced matrix flaw size and S is the inter-fiber spacing. For small ratios, the effect of fiber additions on enhancing MCIS are minimal. As the ratio approaches unity, the role of the fibers in constraining the inherent flaw increases, thereby increasing the MCIS. Thermal residual stresses were also seen to play an important role in determining the MCIS; systems with compressive residual stresses in the matrix show higher MCIS at room temperature than at a higher temperature. In systems such as the 7740/Nicalon, which had negligible thermal stresses, MCIS showed minimal changes on testing at 520 C. Several theoretical models were reviewed and the predictions were compared to the experimental results. It was
Shrinkage estimation of the realized relationship matrix
Technology Transfer Automated Retrieval System (TEKTRAN)
The additive relationship matrix plays an important role in mixed model prediction of breeding values. For genotype matrix X (loci in columns), the product XX' is widely used as a realized relationship matrix, but the scaling of this matrix is ambiguous. Our first objective was to derive a proper ...
MatrixExplorer: a dual-representation system to explore social networks.
Henry, Nathalie; Fekete, Jean-Daniel
2006-01-01
MatrixExplorer is a network visualization system that uses two representations: node-link diagrams and matrices. Its design comes from a list of requirements formalized after several interviews and a participatory design session conducted with social science researchers. Although matrices are commonly used in social networks analysis, very few systems support the matrix-based representations to visualize and analyze networks. MatrixExplorer provides several novel features to support the exploration of social networks with a matrix-based representation, in addition to the standard interactive filtering and clustering functions. It provides tools to reorder (layout) matrices, to annotate and compare findings across different layouts and find consensus among several clusterings. MatrixExplorer also supports Node-link diagram views which are familiar to most users and remain a convenient way to publish or communicate exploration results. Matrix and node-link representations are kept synchronized at all stages of the exploration process.
A Contemporary Matrix Approach to Defining Shared Governance.
ERIC Educational Resources Information Center
Davenport, Richard; Daniels, Elaine; Jones, James; Kesseler, Roger; Mowrey, Merlyn
This paper outlines a matrix approach to shared governance developed at Central Michigan University (CMU), designed to help faculty and administrators focus on specific decision areas and to define existing roles more clearly. The process began at CMU in spring 1998 with the formation of an ad hoc committee on governance which surveyed faculty and…
Joining and fabrication of metal-matrix composite materials
NASA Technical Reports Server (NTRS)
Royster, D. M.; Wiant, H. R.; Bales, T. T.
1975-01-01
Manufacturing technology associated with developing fabrication processes to incorporate metal-matrix composites into flight hardware is studied. The joining of composite to itself and to titanium by innovative brazing, diffusion bonding, and adhesive bonding is examined. The effects of the fabrication processes on the material properties and their influence on the design of YF-12 wing panels are discussed.
A Screening Matrix for an Initial Line of Inquiry
ERIC Educational Resources Information Center
Nordness, Philip D.; Swain, Kristine D.; Haverkost, Ann
2012-01-01
The Screening for Understanding: Initial Line of Inquiry was designed to be used in conjunction with the child study team planning process for dealing with continuous problem behaviors prior to conducting a formal functional behavioral assessment. To conduct the initial line of inquiry a one-page reproducible screening matrix was used during child…
Biofilm Matrix Regulation by Candida albicans Zap1
Nobile, Clarissa J.; Nett, Jeniel E.; Hernday, Aaron D.; Homann, Oliver R.; Deneault, Jean-Sebastien; Nantel, Andre; Andes, David R.; Johnson, Alexander D.; Mitchell, Aaron P.
2009-01-01
A biofilm is a surface-associated population of microorganisms embedded in a matrix of extracellular polymeric substances. Biofilms are a major natural growth form of microorganisms and the cause of pervasive device-associated infection. This report focuses on the biofilm matrix of Candida albicans, the major fungal pathogen of humans. We report here that the C. albicans zinc-response transcription factor Zap1 is a negative regulator of a major matrix component, soluble β-1,3 glucan, in both in vitro and in vivo biofilm models. To understand the mechanistic relationship between Zap1 and matrix, we identified Zap1 target genes through expression profiling and full genome chromatin immunoprecipitation. On the basis of these results, we designed additional experiments showing that two glucoamylases, Gca1 and Gca2, have positive roles in matrix production and may function through hydrolysis of insoluble β-1,3 glucan chains. We also show that a group of alcohol dehydrogenases Adh5, Csh1, and Ifd6 have roles in matrix production: Adh5 acts positively, and Csh1 and Ifd6, negatively. We propose that these alcohol dehydrogenases generate quorum-sensing aryl and acyl alcohols that in turn govern multiple events in biofilm maturation. Our findings define a novel regulatory circuit and its mechanism of control of a process central to infection. PMID:19529758
A high-power X-band Butler matrix
NASA Astrophysics Data System (ADS)
Levy, R.
1984-04-01
A Butler matrix or array is an antenna beam-forming network using a combination of hybrids and fixed phase shifters. The Butler matrix has the property that a signal incident at each input port provides equal amplitude signals at the N output ports. The present investigation is concerned with the feasibility of constructing a Butler matrix in X-band, using a rectangular waveguide to obtain high peak power capability. The considered design and development program consists of two phases. In phase one, prior to building the actual matrix, a computer analysis of the microwave circuit was conducted, and studies of physical configurations and the associated mechanical problems were performed. Phase two involved the design, construction, and testing of an eight-element Butler matrix for the 9.5-10.0 GHz band. Attention is given to synthesis and analysis theory, a high-power phasor problem solution, the analysis of Butler matrices with imperfect components, physical layouts, and aspects of manufacture, assembly, tuning, and testing.
[Matrix Support: a bibliographical study].
Iglesias, Alexandra; Avellar, Luziane Zacché
2014-09-01
This article presents a bibliographical review of matrix support in mental health. A search was conducted in the Virtual Health Library and the LILACS, SciELO and Google Scholar databases using the key words: "matrix support in mental health." Fourteen articles were located with the desired characteristics, which indicates that only a restricted number of publications are in circulation. The articles were analyzed with respect to their structural and methodological aspects, which revealed the absolute predominance of the use of qualitative methods and health professionals as the target research population. The same articles were then analyzed for their theoretical discussions. Among other issues, the importance of matrix support to enhance the primary health care teams provided to people suffering from psychic distress is highlighted. However, there is still considerable confusion regarding the proposal of the matrix support and shared responsibilities between teams of reference and mental health professionals, which emphasizes the need for training of these professionals, as well as better coordination and organization of the mental health care network.
Integrability and generalized monodromy matrix
Lhallabi, T.; Moujib, A.
2007-09-15
We construct the generalized monodromy matrix M-circumflex({omega}) of two-dimensional string effective action by introducing the T-duality group properties. The integrability conditions with general solutions depending on spectral parameter are given. This construction is investigated for the exactly solvable Wess, Zumino, Novikov, and Witten model in pp-wave limit when B=0.
The Enrollment Analysis Matrix Concept.
ERIC Educational Resources Information Center
Chisholm, Mark
The underlying assumptions and the structure of the enrollment analysis matrix (EAM) concept are discussed. EAM is a component of the Strategic Planning Project of the National Center for Higher Education Management Systems. EAM relates changes in the population of potential students external to the institution to the impacts that might result…
NASA Astrophysics Data System (ADS)
Kuhapatanakul, Kantaphon
2015-11-01
In this note, we study the Fibonacci and Lucas p-numbers. We introduce the Lucas p-matrix and companion matrices for the sums of the Fibonacci and Lucas p-numbers to derive some interesting identities of the Fibonacci and Lucas p-numbers.
Matrix Algorithms in Signal Processing
1990-08-01
low rank perturbations with applications, SIAM J. MATRIX ANAL. APPL. 9, 40-58 (1988). [2] (with P . Arbenz and W. Gander), Restricted rank...key idea is to approximate the secular equation by an integral and then bound the integral using the ideas of Gauss- Radau integration. The Lanczos
NASA Astrophysics Data System (ADS)
Lü, Ling; Liu, Shuo; Li, Gang; Zhao, Guannan; Gu, Jiajia; Tian, Jing; Wang, Zhouyang
2016-11-01
In this paper, we research the outer synchronization among discrete networks with different topologies. Based on Lyapunov theorem, a novel synchronization technique is designed. Further, the control inputs of the networks and the adaptive laws of configuration matrix element are obtained. In the end, a numerical example is given to illustrate the effectiveness of the synchronization technique. It is found that the designed control input of the networks ensures the convergence of the errors among the networks to zero. And the designed adaptive law of configuration matrix element can replace effectively configuration matrix element in networks.
Toeplitz block circulant matrix optimized with particle swarm optimization for compressive imaging
NASA Astrophysics Data System (ADS)
Tao, Huifeng; Yin, Songfeng; Tang, Cong
2016-10-01
Compressive imaging is an imaging way based on the compressive sensing theory, which could achieve to capture the high resolution image through a small set of measurements. As the core of the compressive imaging, the design of the measurement matrix is sufficient to ensure that the image can be recovered from the measurements. Due to the fast computing capacity and the characteristic of easy hardware implementation, The Toeplitz block circulant matrix is proposed to realize the encoded samples. The measurement matrix is usually optimized for improving the image reconstruction quality. However, the existing optimization methods can destroy the matrix structure easily when applied to the Toeplitz block circulant matrix optimization process, and the deterministic iterative processes of them are inflexible, because of requiring the task optimized to need to satisfy some certain mathematical property. To overcome this problem, a novel method of optimizing the Toeplitz block circulant matrix based on the particle swarm optimization intelligent algorithm is proposed in this paper. The objective function is established by the way of approaching the target matrix that is the Gram matrix truncated by the Welch threshold. The optimized object is the vector composed by the free entries instead of the Gram matrix. The experimental results indicate that the Toeplitz block circulant measurement matrix can be optimized while preserving the matrix structure by our method, and result in the reconstruction quality improvement.
ERIC Educational Resources Information Center
Caldwell, Benjamin; Rohlman, Christopher; Benore-Parsons, Marilee
2004-01-01
We have designed a skills matrix to be used for developing and assessing undergraduate biochemistry and molecular biology laboratory curricula. We prepared the skills matrix for the Project Kaleidoscope Summer Institute workshop in Snowbird, Utah (July 2001) to help current and developing undergraduate biochemistry and molecular biology program…
Turbine Air-Flow Test Rig CFD Results for Test Matrix
NASA Technical Reports Server (NTRS)
Wilson, Josh
2003-01-01
This paper presents the Turbine Air-Flow Test (TAFT) rig computational fluid dynamics (CFD) results for test matrix. The topics include: 1) TAFT Background; 2) Design Point CFD; 3) TAFT Test Plan and Test Matrix; and 4) CFD of Test Points. This paper is in viewgraph form.
Printing microstructures in a polymer matrix using a ferrofluid droplet
NASA Astrophysics Data System (ADS)
Abdel Fattah, Abdel Rahman; Ghosh, Suvojit; Puri, Ishwar K.
2016-03-01
We print complex curvilinear microstructures in an elastomer matrix using a ferrofluid droplet as the print head. A magnetic field moves the droplet along a prescribed path in liquid polydimethylsiloxane (PDMS). The droplet sheds magnetic nanoparticle (MNP) clusters in its wake, forming printed features. The PDMS is subsequently heated so that it crosslinks, which preserves the printed features in the elastomer matrix. The competition between magnetic and drag forces experienced by the ferrofluid droplet and its trailing MNPs highlight design criteria for successful printing, which are experimentally confirmed. The method promises new applications, such as flexible 3D circuitry.
Structural bases for substrate and inhibitor recognition by matrix metalloproteinases.
Aureli, Loretta; Gioia, Magda; Cerbara, Ilaria; Monaco, Susanna; Fasciglione, Giovanni Francesco; Marini, Stefano; Ascenzi, Paolo; Topai, Alessandra; Coletta, Massimo
2008-01-01
Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases which are involved in the proteolytic processing of several components of the extracellular matrix. As a consequence, MMPs are implicated in several physiological and pathological processes, like skeletal growth and remodelling, wound healing, cancer, arthritis, and multiple sclerosis, raising a very widespread interest toward this class of enzymes as potential therapeutic targets. Here, structure-function relationships are discussed to highlight the role of different MMP domains on substrate/inhibitor recognition and processing and to attempt the formulation of advanced guidelines, based on natural substrates, for the design of inhibitors more efficient in vivo.
q-Virasoro constraints in matrix models
NASA Astrophysics Data System (ADS)
Nedelin, Anton; Zabzine, Maxim
2017-03-01
The Virasoro constraints play the important role in the study of matrix models and in understanding of the relation between matrix models and CFTs. Recently the localization calculations in supersymmetric gauge theories produced new families of matrix models and we have very limited knowledge about these matrix models. We concentrate on elliptic generalization of hermitian matrix model which corresponds to calculation of partition function on S 3 × S 1 for vector multiplet. We derive the q-Virasoro constraints for this matrix model. We also observe some interesting algebraic properties of the q-Virasoro algebra.
Chemical Biology for Understanding Matrix Metalloproteinase Function
Knapinska, Anna; Fields, Gregg B.
2013-01-01
The matrix metalloproteinase (MMP) family has long been associated with normal physiological processes such as embryonic implantation, tissue remodeling, organ development, and wound healing, as well as multiple aspects of cancer initiation and progression, osteoarthritis, inflammatory and vascular diseases, and neurodegenerative diseases. The development of chemically designed MMP probes has advanced our understanding of the roles of MMPs in disease in addition to shedding considerable light on the mechanisms of MMP action. The first generation of protease-activated agents has demonstrated proof of principle as well as providing impetus for in vivo applications. One common problem has been a lack of agent stability at nontargeted tissues and organs due to activation by multiple proteases. The present review considers how chemical biology has impacted the progress made in understanding the roles of MMPs in disease and the basic mechanisms of MMP action. PMID:22933318
Random Matrix Theory in molecular dynamics analysis.
Palese, Luigi Leonardo
2015-01-01
It is well known that, in some situations, principal component analysis (PCA) carried out on molecular dynamics data results in the appearance of cosine-shaped low index projections. Because this is reminiscent of the results obtained by performing PCA on a multidimensional Brownian dynamics, it has been suggested that short-time protein dynamics is essentially nothing more than a noisy signal. Here we use Random Matrix Theory to analyze a series of short-time molecular dynamics experiments which are specifically designed to be simulations with high cosine content. We use as a model system the protein apoCox17, a mitochondrial copper chaperone. Spectral analysis on correlation matrices allows to easily differentiate random correlations, simply deriving from the finite length of the process, from non-random signals reflecting the intrinsic system properties. Our results clearly show that protein dynamics is not really Brownian also in presence of the cosine-shaped low index projections on principal axes.
Ceramic - Matrix Composites for Extreme Applications
NASA Astrophysics Data System (ADS)
Ortona, A.; Gaia, D.; Maiola, G.; Capelari, T.; Mannarino, L.; Pin, F.; Ghisolfi, E.
2008-06-01
Hi-tech systems whose components operate in working conditions characterised by a chemically aggressive environment and elevated temperatures (above 1000°C) are ever more numerous. If metallic materials are not suitably protected and cooled under these conditions, they operate at the limit of their capacity and therefore the integrity of the component can not be guaranteed. Their cooling may furthermore constitute considerable complications in terms of their design. Ceramic materials are a category of materials that bears such extreme working conditions well. However, these materials are actually scarcely used due to their fragility. This limit is overcome by Ceramic Matrix Composites materials (CMCs). All the technologies introduced in this study are developed at FN S.P.A.
Scrambling with matrix black holes
NASA Astrophysics Data System (ADS)
Brady, Lucas; Sahakian, Vatche
2013-08-01
If black holes are not to be dreaded sinks of information but rather fully described by unitary evolution, they must scramble in-falling data and eventually leak it through Hawking radiation. Sekino and Susskind have conjectured that black holes are fast scramblers; they generate entanglement at a remarkably efficient rate, with the characteristic time scaling logarithmically with the entropy. In this work, we focus on Matrix theory—M-theory in the light-cone frame—and directly probe the conjecture. We develop a concrete test bed for quantum gravity using the fermionic variables of Matrix theory and show that the problem becomes that of chains of qubits with an intricate network of interactions. We demonstrate that the black hole system evolves much like a Brownian quantum circuit, with strong indications that it is indeed a fast scrambler. We also analyze the Berenstein-Maldacena-Nastase model and reach the same tentative conclusion.
Sapphire reinforced alumina matrix composites
NASA Technical Reports Server (NTRS)
Jaskowiak, Martha H.; Setlock, John A.
1994-01-01
Unidirectionally reinforced A1203 matrix composites have been fabricated by hot pressing. Approximately 30 volume % of either coated or uncoated sapphire fiber was used as reinforcement. Unstabilized ZrO2 was applied as the fiber coating. Composite mechanical behavior was analyzed both after fabrication and after additional heat treatment. The results of composite tensile tests were correlated with fiber-matrix interfacial shear strengths determined from fiber push-out tests. Substantially higher strength and greater fiber pull-out were observed for the coated fiber composites for all processing conditions studied. The coated fiber composites retained up to 95% and 87% of their as-fabricated strength when heat treated at 14000C for 8 or 24 hours, respectively. Electron microscopy analysis of the fracture surfaces revealed extensive fiber pull-out both before and after heat treatment.
Corrosion of Titanium Matrix Composites
Covino, B.S., Jr.; Alman, D.E.
2002-09-22
The corrosion behavior of unalloyed Ti and titanium matrix composites containing up to 20 vol% of TiC or TiB{sub 2} was determined in deaerated 2 wt% HCl at 50, 70, and 90 degrees C. Corrosion rates were calculated from corrosion currents determined by extrapolation of the tafel slopes. All curves exhibited active-passive behavior but no transpassive region. Corrosion rates for Ti + TiC composites were similar to those for unalloyed Ti except at 90 degrees C where the composites were slightly higher. Corrosion rates for Ti + TiB{sub 2} composites were generally higher than those for unalloyed Ti and increased with higher concentrations of TiB{sub 2}. XRD and SEM-EDS analyses showed that the TiC reinforcement did not react with the Ti matrix during fabrication while the TiB{sub 2} reacted to form a TiB phase.
High temperature polymer matrix composites
NASA Technical Reports Server (NTRS)
Meador, Michael A.
1987-01-01
With the increased emphasis on high performance aircraft the need for lightweight, thermal/oxidatively stable materials is growing. Because of their ease of fabrication, high specific strength, and ability to be tailored chemically to produce a variety of mechanical and physical properties, polymers and polymer matrix composites present themselves as attractive materials for a number of aeropropulsion applications. In the early 1970s researchers at the NASA Lewis Research Center developed a highly processable, thermally stable (600 F) polyimide, PMR-15. Since that time, PMR-15 has become commercially available and has found use in military aircraft, in particular, the F-404 engine for the Navy's F/A-18 strike fighter. The NASA Lewis'contributions to high temperature polymer matrix composite research will be discussed as well as current and future directions.
SALTSTONE MATRIX CHARACTERIZATION AND STADIUM SIMULATION RESULTS
Langton, C.
2009-07-30
less than that expected for saltstone containing the reference amount of slag (45 wt.% of the total cementitious mixture versus 21 wt.% used in the SIMCO samples). Consequently the SIMCO saltstone samples are expected to have lower strengths, and tortuosity and higher porosity, water diffusivity, and intrinsic permeability compared to the reference case MCU saltstone. MCU reference saltstone contains nonradioactive salt solution with a composition designed to simulate the product of the Modular Caustic Side Solvent Extraction (MCU) Unit [Harbour, 2009]. The SIMCO saltstone samples were cast in molds and cured for three days under plastic with a source of water to prevent drying. Details of the sample preparation process are presented in Attachment 2. The molds were then removed and the samples were cured at a constant temperature (76 F, 24 C) and 100 percent relative humidity for up to one year. Selected samples were periodically removed and characterized the evolution of the matrix as a function of age. In order to preserve the age dependent microstructure at the specified curing times it is necessary to stop hydration. This was accomplished by immersing the samples in isopropanol for 5 days to replace water with alcohol. The microstructure of the matrix material was also characterized as a function of aging. This information was used as a base line for comparison with leached microstructures. After curing for 137 days, specimens were cut into 20 mm disks and exposed to deionized water with a pH maintained at 10.5. Microstructure and calcium sulfur leaching results for samples leached for 31 days are presented in this report. Insufficient leached material was generated during the testing to date to obtain physical and mineralogical properties for leached saltstone. Longer term experiments are required because the matrix alteration rate due to immersion in deionized water is slow.
Myocardial structure and matrix metalloproteinases.
Aggeli, C; Pietri, P; Felekos, I; Rautopoulos, L; Toutouzas, K; Tsiamis, E; Stefanadis, C
2012-01-01
Metalloproteinases (MMPs) are enzymes which enhance proteolysis of extracellular matrix proteins. The pathophysiologic and prognostic role of MMPs has been demonstrated in numerous studies. The present review covers a wide a range of topics with regards to MMPs structural and functional properties, as well as their role in myocardial remodeling in several cardiovascular diseases. Moreover, the clinical and therapeutic implications from their assessment are highlighted.
Tough high performance composite matrix
NASA Technical Reports Server (NTRS)
Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)
1994-01-01
This invention is a semi-interpentrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. Provided is an improved high temperature matrix resin which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance, and moisture and solvent resistances.
Integrable matrix theory: Level statistics.
Scaramazza, Jasen A; Shastry, B Sriram; Yuzbashyan, Emil A
2016-09-01
We study level statistics in ensembles of integrable N×N matrices linear in a real parameter x. The matrix H(x) is considered integrable if it has a prescribed number n>1 of linearly independent commuting partners H^{i}(x) (integrals of motion) [H(x),H^{i}(x)]=0, [H^{i}(x),H^{j}(x)]=0, for all x. In a recent work [Phys. Rev. E 93, 052114 (2016)2470-004510.1103/PhysRevE.93.052114], we developed a basis-independent construction of H(x) for any n from which we derived the probability density function, thereby determining how to choose a typical integrable matrix from the ensemble. Here, we find that typical integrable matrices have Poisson statistics in the N→∞ limit provided n scales at least as logN; otherwise, they exhibit level repulsion. Exceptions to the Poisson case occur at isolated coupling values x=x_{0} or when correlations are introduced between typically independent matrix parameters. However, level statistics cross over to Poisson at O(N^{-0.5}) deviations from these exceptions, indicating that non-Poissonian statistics characterize only subsets of measure zero in the parameter space. Furthermore, we present strong numerical evidence that ensembles of integrable matrices are stationary and ergodic with respect to nearest-neighbor level statistics.
MALDI Matrix Research for Biopolymers
Fukuyama, Yuko
2015-01-01
Matrices are necessary materials for ionizing analytes in matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). The choice of a matrix appropriate for each analyte controls the analyses. Thus, in some cases, development or improvement of matrices can become a tool for solving problems. This paper reviews MALDI matrix research that the author has conducted in the recent decade. It describes glycopeptide, carbohydrate, or phosphopeptide analyses using 2,5-dihydroxybenzoic acid (2,5-DHB), 1,1,3,3-tetramethylguanidinium (TMG) salts of p-coumaric acid (CA) (G3CA), 3-aminoquinoline (3-AQ)/α-cyano-4-hydroxycinnamic acid (CHCA) (3-AQ/CHCA) or 3-AQ/CA and gengeral peptide, peptide containing disulfide bonds or hydrophobic peptide analyses using butylamine salt of CHCA (CHCAB), 1,5-diaminonaphthalene (1,5-DAN), octyl 2,5-dihydroxybenzoate (alkylated dihydroxybenzoate, ADHB), or 1-(2,4,6-trihydroxyphenyl)octan-1-one (alkylated trihydroxyacetophenone, ATHAP). PMID:26819908
A path-oriented matrix-based knowledge representation system
NASA Technical Reports Server (NTRS)
Feyock, Stefan; Karamouzis, Stamos T.
1993-01-01
Experience has shown that designing a good representation is often the key to turning hard problems into simple ones. Most AI (Artificial Intelligence) search/representation techniques are oriented toward an infinite domain of objects and arbitrary relations among them. In reality much of what needs to be represented in AI can be expressed using a finite domain and unary or binary predicates. Well-known vector- and matrix-based representations can efficiently represent finite domains and unary/binary predicates, and allow effective extraction of path information by generalized transitive closure/path matrix computations. In order to avoid space limitations a set of abstract sparse matrix data types was developed along with a set of operations on them. This representation forms the basis of an intelligent information system for representing and manipulating relational data.
Matrix-dominated mechanical properties of a fiber composite lamina
Lyon, R.E.; Schumann, D.L.; DeTeresa, S.J.
1992-05-18
Matrix-dominated mechanical properties of unidirectional fiber composite laminae were determined from hoop-wound tube specimens and cylindrical rods fabricated from both wet-filament winding and prepreg material systems. Longitudinal shear modulus and strength as well as transverse Young's modulus, transverse tensile strength, and transverse compressive strength were obtained from a thin-walled tube specimen using a new fixturing design. Lamina properties are presented for several carbon fiber/epoxy composite materials. Longitudinal shear moduli were measured for both tubes and rods in torsion. Results obtained in the linear-elastic regimes above and below the glass transition temperature (Tg) of the matrix phase were compared with micromechanics predictions. Although agreement between predicted and measured shear moduli was reasonable below Tg, large discrepancies were observed when the matrix phase was elastomeric.
Matrix-dominated mechanical properties of a fiber composite lamina
Lyon, R.E.; Schumann, D.L.; DeTeresa, S.J.
1992-05-18
Matrix-dominated mechanical properties of unidirectional fiber composite laminae were determined from hoop-wound tube specimens and cylindrical rods fabricated from both wet-filament winding and prepreg material systems. Longitudinal shear modulus and strength as well as transverse Young`s modulus, transverse tensile strength, and transverse compressive strength were obtained from a thin-walled tube specimen using a new fixturing design. Lamina properties are presented for several carbon fiber/epoxy composite materials. Longitudinal shear moduli were measured for both tubes and rods in torsion. Results obtained in the linear-elastic regimes above and below the glass transition temperature (Tg) of the matrix phase were compared with micromechanics predictions. Although agreement between predicted and measured shear moduli was reasonable below Tg, large discrepancies were observed when the matrix phase was elastomeric.
Matrix Formulation of Pebble Circulation in the PEBBED Code
Gougar, Hans D; Terry, William Knox; Ougouag, Abderrafi Mohammed-El-Ami
2002-04-01
The PEBBED technique provides a foundation for equilibrium fuel-cycle analysis and optimization in pebble-bed cores in which the fuel elements are continuously flowing and, if desired, recirculating. In addition to the modern analysis techniques used in, or being developed for, the code, PEBBED incorporates a novel nuclide-mixing algorithm that allows for sophisticated recirculation patterns using a matrix generated from basic core parameters. Derived from a simple partitioning of the pebble flow, the elements of the recirculation matrix are used to compute the spatially averaged density of each nuclide at the entry plane from the nuclide densities of pebbles emerging from the discharge conus. The order of the recirculation matrix is a function of the flexibility and sophistication of the fuel handling mechanism. This formulation for coupling pebble flow and neutronics enables core design and fuel cycle optimization to be performed by manipulating a few key core parameters. The formulation is amenable to modern optimization techniques.
Matrix-based image reconstruction methods for tomography
Llacer, J.; Meng, J.D.
1984-10-01
Matrix methods of image reconstruction have not been used, in general, because of the large size of practical matrices, ill condition upon inversion and the success of Fourier-based techniques. An exception is the work that has been done at the Lawrence Berkeley Laboratory for imaging with accelerated radioactive ions. An extension of that work into more general imaging problems shows that, with a correct formulation of the problem, positron tomography with ring geometries results in well behaved matrices which can be used for image reconstruction with no distortion of the point response in the field of view and flexibility in the design of the instrument. Maximum Likelihood Estimator methods of reconstruction, which use the system matrices tailored to specific instruments and do not need matrix inversion, are shown to result in good preliminary images. A parallel processing computer structure based on multiple inexpensive microprocessors is proposed as a system to implement the matrix-MLE methods. 14 references, 7 figures.
Solid oxide fuel cell matrix and modules
Riley, Brian
1990-01-01
Porous refractory ceramic blocks arranged in an abutting, stacked configuration and forming a three dimensional array provide a support structure and coupling means for a plurality of solid oxide fuel cells (SOFCs). Each of the blocks includes a square center channel which forms a vertical shaft when the blocks are arranged in a stacked array. Positioned within the channel is a SOFC unit cell such that a plurality of such SOFC units disposed within a vertical shaft form a string of SOFC units coupled in series. A first pair of facing inner walls of each of the blocks each include an interconnecting channel hole cut horizontally and vertically into the block walls to form gas exit channels. A second pair of facing lateral walls of each block further include a pair of inner half circular grooves which form sleeves to accommodate anode fuel and cathode air tubes. The stack of ceramic blocks is self-supporting, with a plurality of such stacked arrays forming a matrix enclosed in an insulating refractory brick structure having an outer steel layer. The necessary connections for air, fuel, burnt gas, and anode and cathode connections are provided through the brick and steel outer shell. The ceramic blocks are so designed with respect to the strings of modules that by simple and logical design the strings could be replaced by hot reloading if one should fail. The hot reloading concept has not been included in any previous designs.
R&D of MCFC matrix for long term operation
Nishimura, Takashi; Fujita, Yoji; Urushibata, Hiroaki; Sasaki, Akira
1996-12-31
Long term operation is an essential subject in the commercialization of the Molten Carbonate Fuel Cell (MCFC). Material stability is important for the development of the MCFC. particularly for long term operation. In this paper, the specification and the stabilization of MCFC matrix arc investigated, with the aim of producing 40000 hours of operation. It is common knowledge that matrix thickness has a large influence on shorting time, as shorting is caused by the dissolution of the nickel oxide cathodes. Therefore, the optimum thickness of a matrix designed for 40000 hours operation without the nickel shorting was sought. The influences of different electrolytes and matrix specifications on the shorting time were measured with accelerated cell tests. The internal resistance of the matrix was also estimated. Gamma( {gamma} )-lithium aluminate (LiAlO{sub 2}) powder with a sub-micron particle diameter is commonly used for a raw material of matrix to retain molten carbonate electrolytes. This is because most researchers found that {gamma}-LiA1O{sub 2} was the most stable material in the MCFC environment among the three allotropic forms alpha ( {alpha} ), beta ( {beta} ), and {gamma}. However. two problems with the stability of {gamma} -LiAlO{sub 2} are being vigorously discussed. especially in Japan: particle growth causes decreasing electrolyte retention, and the transformation of {gamma} to {alpha}. This transformation contradicts the accepted opinion that {gamma} is the most stable form. In this paper, the particle growth and the phase transformation of LiAlO{sub 2} are examined with post-test analyses. The influence of matrix degradation on cell performance is also considered.
Advanced Ceramic Matrix Composites with Multifunctional and Hybrid Structures
NASA Technical Reports Server (NTRS)
Singh, Mrityunjay; Morscher, Gregory N.
2004-01-01
Ceramic matrix composites are leading candidate materials for a number of applications in aeronautics, space, energy, and nuclear industries. Potential composite applications differ in their requirements for thickness. For example, many space applications such as "nozzle ramps" or "heat exchangers" require very thin (< 1 mm) structures whereas turbine blades would require very thick parts (> or = 1 cm). Little is known about the effect of thickness on stress-strain behavior or the elevated temperature tensile properties controlled by oxidation diffusion. In this study, composites consisting of woven Hi-Nicalon (trademark) fibers a carbon interphase and CVI SiC matrix were fabricated with different numbers of plies and thicknesses. The effect of thickness on matrix crack formation, matrix crack growth and diffusion kinetics will be discussed. In another approach, hybrid fiber-lay up concepts have been utilized to "alloy" desirable properties of different fiber types for mechanical properties, thermal stress management, and oxidation resistance. Such an approach has potential for the C(sub I)-SiC and SiC(sub f)-SiC composite systems. CVI SiC matrix composites with different stacking sequences of woven C fiber (T300) layers and woven SiC fiber (Hi-Nicalon (trademark)) layers were fabricated. The results will be compared to standard C fiber reinforced CVI SiC matrix and Hi-Nicalon reinforced CVI SiC matrix composites. In addition, shear properties of these composites at different temperatures will also be presented. Other design and implementation issues will be discussed along with advantages and benefits of using these materials for various components in high temperature applications.
The Cloutterbuck Minimum Data Matrix: A Teaching Mechanism for the New Millennium.
ERIC Educational Resources Information Center
Cloutterbuck, Jane C.; Cherry, Brenda S.
1998-01-01
The Cloutterbuck Minimum Data Matrix is designed to generate a base of consumer information for critical analysis and synthesis to produce health care outcomes. The interdisciplinary teaching tool helps students recognize the diversity of health care consumers. (SK)
Fast polar decomposition of an arbitrary matrix
NASA Technical Reports Server (NTRS)
Higham, Nicholas J.; Schreiber, Robert S.
1988-01-01
The polar decomposition of an m x n matrix A of full rank, where m is greater than or equal to n, can be computed using a quadratically convergent algorithm. The algorithm is based on a Newton iteration involving a matrix inverse. With the use of a preliminary complete orthogonal decomposition the algorithm can be extended to arbitrary A. How to use the algorithm to compute the positive semi-definite square root of a Hermitian positive semi-definite matrix is described. A hybrid algorithm which adaptively switches from the matrix inversion based iteration to a matrix multiplication based iteration due to Kovarik, and to Bjorck and Bowie is formulated. The decision when to switch is made using a condition estimator. This matrix multiplication rich algorithm is shown to be more efficient on machines for which matrix multiplication can be executed 1.5 times faster than matrix inversion.
Modeling the Mechanical Behavior of Ceramic Matrix Composite Materials
NASA Technical Reports Server (NTRS)
Jordan, William
1998-01-01
Ceramic matrix composites are ceramic materials, such as SiC, that have been reinforced by high strength fibers, such as carbon. Designers are interested in using ceramic matrix composites because they have the capability of withstanding significant loads while at relatively high temperatures (in excess of 1,000 C). Ceramic matrix composites retain the ceramic materials ability to withstand high temperatures, but also possess a much greater ductility and toughness. Their high strength and medium toughness is what makes them of so much interest to the aerospace community. This work concentrated on two different tasks. The first task was to do an extensive literature search into the mechanical behavior of ceramic matrix composite materials. This report contains the results of this task. The second task was to use this understanding to help interpret the ceramic matrix composite mechanical test results that had already been obtained by NASA. Since the specific details of these test results are subject to the International Traffic in Arms Regulations (ITAR), they are reported in a separate document (Jordan, 1997).
Metal-matrix composites: Status and prospects
NASA Technical Reports Server (NTRS)
1974-01-01
Applications of metal matrix composites for air frames and jet engine components are discussed. The current state of the art in primary and secondary fabrication is presented. The present and projected costs were analyzed to determine the cost effectiveness of metal matrix composites. The various types of metal matrix composites and their characteristics are described.
Rotation of hard particles in a soft matrix
NASA Astrophysics Data System (ADS)
Yang, Weizhu; Liu, Qingchang; Yue, Zhufeng; Li, Xiaodong; Xu, Baoxing
Soft-hard materials integration is ubiquitous in biological materials and structures in nature and has also attracted growing attention in the bio-inspired design of advanced functional materials, structures and devices. Due to the distinct difference in their mechanical properties, the rotation of hard phases in soft matrixes upon deformation has been acknowledged, yet is lack of theory in mechanics. In this work, we propose a theoretical mechanics framework that can describe the rotation of hard particles in a soft matrix. The rotation of multiple arbitrarily shaped, located and oriented particles with perfectly bonded interfaces in an elastic soft matrix subjected to a far-field tensile loading is established and analytical solutions are derived by using complex potentials and conformal mapping methods. Strong couplings and competitions of the rotation of hard particles among each other are discussed by investigating numbers, relative locations and orientations of particles in the matrix at different loading directions. Extensive finite element analyses are performed to validate theoretical solutions and good agreement of both rotation and stress field between them are achieved. Possible extensions of the present theory to non-rigid particles, viscoelastic matrix and imperfect bonding are also discussed. Finally, by taking advantage of the rotation of hard particles, we exemplify an application in a conceptual design of soft-hard material integrated phononic crystal and demonstrate that phononic band gaps can be successfully tuned with a high accuracy through the mechanical tension-induced rotation of hard particles. The present theory established herein is expected to be of immediate interests to the design of soft-hard materials integration based functional materials, structures and devices with tunable performance via mechanical rotation of hard phases.
Immunomodulatory effects of amniotic membrane matrix incorporated into collagen scaffolds
Hortensius, Rebecca A.; Ebens, Jill H.; Harley, Brendan A. C.
2016-01-01
Adult tendon wound repair is characterized by the formation of disorganized collagen matrix which leads to decreases in mechanical properties and scar formation. Studies have linked this scar formation to the inflammatory phase of wound healing. Instructive biomaterials designed for tendon regeneration are often designed to provide both structural and cellular support. In order to facilitate regeneration, success may be found by tempering the body’s inflammatory response. This work combines collagen-glycosaminoglycan scaffolds, previously developed for tissue regeneration, with matrix materials (hyaluronic acid and amniotic membrane) that have been shown to promote healing and decreased scar formation in skin studies. The results presented show that scaffolds containing amniotic membrane matrix have significantly increased mechanical properties and that tendon cells within these scaffolds have increased metabolic activity even when the media is supplemented with the pro-inflammatory cytokine interleukin-1 beta. Collagen scaffolds containing hyaluronic acid or amniotic membrane also temper the expression of genes associated with the inflammatory response in normal tendon healing (TNF-α, COLI, MMP-3). These results suggest that alterations to scaffold composition, to include matrix known to decrease scar formation in vivo, can modify the inflammatory response in tenocytes. PMID:26799369
Teaching Tip: When a Matrix and Its Inverse Are Stochastic
ERIC Educational Resources Information Center
Ding, J.; Rhee, N. H.
2013-01-01
A stochastic matrix is a square matrix with nonnegative entries and row sums 1. The simplest example is a permutation matrix, whose rows permute the rows of an identity matrix. A permutation matrix and its inverse are both stochastic. We prove the converse, that is, if a matrix and its inverse are both stochastic, then it is a permutation matrix.
Fiber-matrix interface failures
NASA Technical Reports Server (NTRS)
Rabenberg, Lew; Marcus, Harris L.; Park, Hun Sub; Zong, Gui Sheng; Brown, Lloyd D.
1989-01-01
Interface fractures of aluminum-graphite composites under transverse loading are expected to occur within the graphite fibers, but very near the interface. Residual stresses in aluminum, reinforced with the new high modulus pitch-based fibers, are much lower than would be expected based on simple elasticity calculations. The excess stress may be relaxed by shearing internal to the fibers or at the interface rather than by plastic flow of the matrix. The internal shearing also occurs during repeated thermal cycling of these composites; the fibers are repeatedly intruded, then extruded, during repeated temperature excursions.
Matrix management for aerospace 2000
NASA Technical Reports Server (NTRS)
Mccarthy, J. F., Jr.
1980-01-01
The martix management approach to program management is an organized effort for attaining program objectives by defining and structuring all elements so as to form a single system whose parts are united by interaction. The objective of the systems approach is uncompromisingly complete coverage of the program management endeavor. Starting with an analysis of the functions necessary to carry out a given program, a model must be defined; a matrix of responsibility assignment must be prepared; and each operational process must be examined to establish how it is to be carried out and how it relates to all other processes.
Diffusive dynamics on paper matrix
NASA Astrophysics Data System (ADS)
Chaudhury, Kaustav; Kar, Shantimoy; Chakraborty, Suman
2016-11-01
Writing with ink on a paper and the rapid diagnostics of diseases using paper cartridge, despite their remarkable diversities from application perspective, both involve the motion of a liquid from a source on a porous hydrophilic substrate. Here we bring out a generalization in the pertinent dynamics by appealing to the concerned ensemble-averaged transport with reference to the underlying molecular picture. Our results reveal that notwithstanding the associated complexities and diversities, the resultant liquid transport characteristics on a paper matrix, in a wide variety of applications, resemble universal diffusive dynamics. Agreement with experimental results from diversified applications is generic and validates our unified theory.
Random matrix theory within superstatistics.
Abul-Magd, A Y
2005-12-01
We propose a generalization of the random matrix theory following the basic prescription of the recently suggested concept of superstatistics. Spectral characteristics of systems with mixed regular-chaotic dynamics are expressed as weighted averages of the corresponding quantities in the standard theory assuming that the mean level spacing itself is a stochastic variable. We illustrate the method by calculating the level density, the nearest-neighbor-spacing distributions, and the two-level correlation functions for systems in transition from order to chaos. The calculated spacing distribution fits the resonance statistics of random binary networks obtained in a recent numerical experiment.
Neonatal disorders of germinal matrix.
Raets, M M A; Dudink, J; Govaert, P
2015-11-01
The germinal matrix (GM) is a richly vascularized, transient layer near the ventricles. It produces neurons and glial cells, and is present in the foetal brain between 8 and 36 weeks of gestation. At 25 weeks, it reaches its maximum volume and subsequently withers. The GM is vulnerable to haemorrhage in preterm infants. This selective vulnerability is explained by limited astrocyte end-feet coverage of microvessels, reduced expression of fibronectin and immature tight junctions. Focal lesions in the neonatal period include haemorrhage, germinolysis and stroke. Such lesions in transient layers interrupt normal brain maturation and induce neurodevelopmental sequelae.
Laminated Object Manufacturing-Based Design Ceramic Matrix Composites
2001-04-01
7 3.1.1-3 Examples of CMC Parts with 0 Gaussian Curvature A) Nicalon/ Blackglas™ Fairing Channel, B) SiC/SiC Engine Flameholders, C) DIMOX ™ Body...CMC Parts with 0 Gaussian Curvature A) Nicalon/ Blackglas™ Fairing Channel, B) SiC/SiC Engine Flameholders, C) DIMOX ™ Body Armor Plate
Modified matrix band design for ultra-conservative posterior restorations.
Deliperi, Simone
2008-01-01
Conventional box preparations, tunnel cavities and slot preparations have been recommended for the treatment of proximal carious lesions over the years. If the adjacent tooth is missing or the proximal surface becomes accessible at the time of cavity preparation of the adjacent tooth, a direct proximal access to the decay process can be performed. A similar procedure is supported by the use of adhesive composite restorations reinforcing the remaining sound tooth structure. The increasing patient and clinician's desire for ultraconservative treatment justifies this minimally invasive tooth preparation approach; however, appropriate materials and techniques need to be selected to achieve adequate bonding of the cavity walls and marginal adaptation of the composite.
The q-Laguerre matrix polynomials.
Salem, Ahmed
2016-01-01
The Laguerre polynomials have been extended to Laguerre matrix polynomials by means of studying certain second-order matrix differential equation. In this paper, certain second-order matrix q-difference equation is investigated and solved. Its solution gives a generalized of the q-Laguerre polynomials in matrix variable. Four generating functions of this matrix polynomials are investigated. Two slightly different explicit forms are introduced. Three-term recurrence relation, Rodrigues-type formula and the q-orthogonality property are given.
On matrix Painlevé hierarchies
NASA Astrophysics Data System (ADS)
Gordoa, P. R.; Pickering, A.; Zhu, Z. N.
2016-07-01
We define a matrix first Painlevé hierarchy and a matrix second Painlevé (PII) hierarchy. For our matrix PII hierarchy we also give auto-Bäcklund transformations and consider the iteration of solutions. This is the first paper to define matrix Painlevé hierarchies and to give auto-Bäcklund transformations for a matrix Painlevé hierarchy. We also consider, amongst other results, the derivation of sequences of special integrals and autonomous limits. Until now it has been unknown how to connect the known matrix PII equation to the obvious candidates for related completely integrable matrix partial differential equations. Our matrix PII hierarchy is placed firmly within the context of a matrix modified Korteweg-de Vries (mKdV) hierarchy. In deriving our matrix PII hierarchy we make use of the Hamiltonian structure of this matrix mKdV hierarchy. We thus see once again the importance for Painlevé hierarchies of the integrability structures of related completely integrable equations.
Matrix stiffening promotes a tumor vasculature phenotype
Bordeleau, Francois; Mason, Brooke N.; Lollis, Emmanuel Macklin; Mazzola, Michael; Zanotelli, Matthew R.; Somasegar, Sahana; Califano, Joseph P.; Montague, Christine; LaValley, Danielle J.; Huynh, John; Mencia-Trinchant, Nuria; Negrón Abril, Yashira L.; Hassane, Duane C.; Bonassar, Lawrence J.; Butcher, Jonathan T.; Weiss, Robert S.; Reinhart-King, Cynthia A.
2017-01-01
Tumor microvasculature tends to be malformed, more permeable, and more tortuous than vessels in healthy tissue, effects that have been largely attributed to up-regulated VEGF expression. However, tumor tissue tends to stiffen during solid tumor progression, and tissue stiffness is known to alter cell behaviors including proliferation, migration, and cell–cell adhesion, which are all requisite for angiogenesis. Using in vitro, in vivo, and ex ovo models, we investigated the effects of matrix stiffness on vessel growth and integrity during angiogenesis. Our data indicate that angiogenic outgrowth, invasion, and neovessel branching increase with matrix cross-linking. These effects are caused by increased matrix stiffness independent of matrix density, because increased matrix density results in decreased angiogenesis. Notably, matrix stiffness up-regulates matrix metalloproteinase (MMP) activity, and inhibiting MMPs significantly reduces angiogenic outgrowth in stiffer cross-linked gels. To investigate the functional significance of altered endothelial cell behavior in response to matrix stiffness, we measured endothelial cell barrier function on substrates mimicking the stiffness of healthy and tumor tissue. Our data indicate that barrier function is impaired and the localization of vascular endothelial cadherin is altered as function of matrix stiffness. These results demonstrate that matrix stiffness, separately from matrix density, can alter vascular growth and integrity, mimicking the changes that exist in tumor vasculature. These data suggest that therapeutically targeting tumor stiffness or the endothelial cell response to tumor stiffening may help restore vessel structure, minimize metastasis, and aid in drug delivery. PMID:28034921
Multifeature focus exposure matrix for tool diagnosis
NASA Astrophysics Data System (ADS)
Yang, Zhiyong; Burov, Anatoly Y.; Duan, Lifeng; Wang, Fan
2011-03-01
Lithographic tool performance is the main contributor to CDU. The tool designers and users require an accurate method to measure the tool's error factors on the wafer side in order to improve CDU. Engineers typically use the FEM method to estimate DOF and EL, and then predict the CDU. However, based on the exposure data, it is often difficult to separate systematic level physical errors, such as DOSE repeatability, focus repeatability, dynamic errors and all the other tool's imperfections. In this paper, we introduce a wafer data based method to diagnose tool's performance for CDU improvement. As the systematic errors have a specific signature, they generate a fingerprint in the exposure data. Based on the knowledge of the exposure process and process flow, multiple dimensions exposure matrix is designed to analyze and diagnose the tool's systematic error from wafer data fingerprint. For SMEE's scanner tool (SSA600/10), we use this method to diagnose tool's systematic error and improve the CDU. Some typical result is represented in this paper.
Link prediction via matrix completion
NASA Astrophysics Data System (ADS)
Pech, Ratha; Hao, Dong; Pan, Liming; Cheng, Hong; Zhou, Tao
2017-02-01
Inspired by the practical importance of social networks, economic networks, biological networks and so on, studies on large and complex networks have attracted a surge of attention in the recent years. Link prediction is a fundamental issue to understand the mechanisms by which new links are added to the networks. We introduce the method of robust principal component analysis (robust PCA) into link prediction, and estimate the missing entries of the adjacency matrix. On the one hand, our algorithm is based on the sparse and low-rank property of the matrix, while, on the other hand, it also performs very well when the network is dense. This is because a relatively dense real network is also sparse in comparison to the complete graph. According to extensive experiments on real networks from disparate fields, when the target network is connected and sufficiently dense, whether it is weighted or unweighted, our method is demonstrated to be very effective and with prediction accuracy being considerably improved compared to many state-of-the-art algorithms.
Extracellular Matrix and Liver Disease
Arriazu, Elena; Ruiz de Galarreta, Marina; Cubero, Francisco Javier; Varela-Rey, Marta; Pérez de Obanos, María Pilar; Leung, Tung Ming; Lopategi, Aritz; Benedicto, Aitor; Abraham-Enachescu, Ioana
2014-01-01
Abstract Significance: The extracellular matrix (ECM) is a dynamic microenvironment that undergoes continuous remodeling, particularly during injury and wound healing. Chronic liver injury of many different etiologies such as viral hepatitis, alcohol abuse, drug-induced liver injury, obesity and insulin resistance, metabolic disorders, and autoimmune disease is characterized by excessive deposition of ECM proteins in response to persistent liver damage. Critical Issues: This review describes the main collagenous and noncollagenous components from the ECM that play a significant role in pathological matrix deposition during liver disease. We define how increased myofibroblasts (MF) from different origins are at the forefront of liver fibrosis and how liver cell-specific regulation of the complex scarring process occurs. Recent Advances: Particular attention is paid to the role of cytokines, growth factors, reactive oxygen species, and newly identified matricellular proteins in the regulation of fibrillar type I collagen, a field to which our laboratory has significantly contributed over the years. We compile data from recent literature on the potential mechanisms driving fibrosis resolution such as MF’ apoptosis, senescence, and reversal to quiescence. Future Directions: We conclude with a brief description of how epigenetics, an evolving field, can regulate the behavior of MF and of how new “omics” tools may advance our understanding of the mechanisms by which the fibrogenic response to liver injury occurs. Antioxid. Redox Signal. 21, 1078–1097. PMID:24219114
Characterization of Metal Matrix Composites
NASA Technical Reports Server (NTRS)
Daniel, I. M.; Chun, H. J.; Karalekas, D.
1994-01-01
Experimental methods were developed, adapted, and applied to the characterization of a metal matrix composite system, namely, silicon carbide/aluminim (SCS-2/6061 Al), and its constituents. The silicon carbide fiber was characterized by determining its modulus, strength, and coefficient of thermal expansion. The aluminum matrix was characterized thermomechanically up to 399 C (750 F) at two strain rates. The unidirectional SiC/Al composite was characterized mechanically under longitudinal, transverse, and in-plane shear loading up to 399 C (750 F). Isothermal and non-isothermal creep behavior was also measured. The applicability of a proposed set of multifactor thermoviscoplastic nonlinear constitutive relations and a computer code was investigated. Agreement between predictions and experimental results was shown in a few cases. The elastoplastic thermomechanical behavior of the composite was also described by a number of new analytical models developed or adapted for the material system studied. These models include the rule of mixtures, composite cylinder model with various thermoelastoplastic analyses and a model based on average field theory. In most cases satisfactory agreement was demonstrated between analytical predictions and experimental results for the cases of stress-strain behavior and thermal deformation behavior at different temperatures. In addition, some models yielded detailed three-dimensional stress distributions in the constituents within the composite.
Matrix metalloproteinases in metabolic syndrome.
Hopps, E; Caimi, G
2012-03-01
Metabolic syndrome is commonly accompanied by an elevated cardiovascular risk with high morbidity and mortality. The alterations of the arterial vasculature begin with endothelial dysfunction and lead to micro- and macrovascular complications. The remodeling of the endothelial basal membrane, that promotes erosion and thrombosis, has a multifactorial pathogenesis that includes leukocyte activation, increased oxidative stress and also an altered matrix metalloproteinases (MMPs) expression. MMPs are endopeptidases which degrade extracellular matrix proteins, such as collagen, gelatins, fibronectin and laminin. They can be secreted by several cells within the vascular wall, but macrophages are determinant in the atherosclerotic plaques. Their activity is regulated by tissue inhibitors of MMP (TIMPs) and also by other molecules, such as plasmin. MMPs could be implicated in plaque instability predisposing to vascular complications. It has been demonstrated that an impaired MMP or TIMP expression is associated with higher risk of all-cause mortality. A large number of studies evaluated MMPs pattern in obesity, diabetes mellitus, arterial hypertension and dyslipidemia, all of which define metabolic syndrome according to several Consensus Statement (i.e. IDF, ATP III, AHA). However, few research have been carried out on subjects with metabolic syndrome. The evidences of an improvement in MMP/TIMP ratio with diet, exercise and medical therapy should encourage further investigations with the intent to contrast the atherosclerotic process and to reduce morbidity and mortality of this kind of patients.
High Strain Rate Behavior of Polymer Matrix Composites Analyzed
NASA Technical Reports Server (NTRS)
Goldberg, Robert K.; Roberts, Gary D.
2001-01-01
Procedures for modeling the high-speed impact of composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. To characterize and validate material models that could be used in the design of impactresistant engine cases, researchers must obtain material data over a wide variety of strain rates. An experimental program has been carried out through a university grant with the Ohio State University to obtain deformation data for a representative polymer matrix composite for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used to characterize and validate a constitutive model that was developed at the NASA Glenn Research Center.
Automatic Generation of Partitioned Matrix Expressions for Matrix Operations
NASA Astrophysics Data System (ADS)
Fabregat-Traver, Diego; Bientinesi, Paolo
2010-09-01
We target the automatic generation of formally correct algorithms and routines for linear algebra operations. Given the broad variety of architectures and configurations with which scientists deal, there does not exist one algorithmic variant that is suitable for all scenarios. Therefore, we aim to generate a family of algorithmic variants to attain high-performance for a broad set of scenarios. One of the authors has previously demonstrated that automatic derivation of a family of algorithms is possible when the Partitioned Matrix Expression (PME) of the target operation is available. The PME is a recursive definition that states the relations between submatrices in the input and the output operands. In this paper we describe all the steps involved in the automatic derivation of PMEs, thus making progress towards a fully automated system.
LAPACK Working Note 9: A test matrix generation suite
Demmel, J.; McKenney, A. . Courant Institute)
1989-02-28
We discuss the design and implementation of a suite of test matrix generators for testing linear algebra software. These routines generate random matrices with certain properties which are useful for testing linear equation solving, least squares, and eigendecomposition software. These properites include the spectrum, symmetry, bandwidth, norm, sparsity, conditioning (with respect to inversion or for the eigenproblem), type (real or complex), and storage scheme (dense, packed or banded).
Managing information systems: an ethical framework and information needs matrix.
Caputo, R K
1991-01-01
This paper urged administrators in human services to attend to values and ethics in the design and implementation of automated information systems. Toward this end, it presented an ethical framework reasserting the primacy of clients as citizens and encouraging the development of client-driven information systems. Finally, the paper presented the rationale for and two examples of an Information Needs Matrix to assist administrators in their deliberations about allocating discretionary resources among functional units within organizations.
Spine fusion using cell matrix composites enriched in bone marrow-derived cells.
Muschler, George F; Nitto, Hironori; Matsukura, Yoichi; Boehm, Cynthia; Valdevit, Antonio; Kambic, Helen; Davros, William; Powell, Kimerly; Easley, Kirk
2003-02-01
Bone marrow-derived cells including osteoblastic progenitors can be concentrated rapidly from bone marrow aspirates using the surface of selected implantable matrices for selective cell attachment. Concentration of cells in this way to produce an enriched cellular composite graft improves graft efficacy. The current study was designed to test the hypothesis that the biologic milieu of a bone marrow clot will significantly improve the efficacy of such a graft. An established posterior spinal fusion model and cancellous bone matrix was used to compare an enriched cellular composite bone graft alone, bone matrix plus bone marrow clot, and an enriched bone matrix composite graft plus bone marrow clot. Union score, quantitative computed tomography, and mechanical testing were used to define outcome. The union score for the enriched bone matrix plus bone marrow clot composite was superior to the enriched bone matrix alone and the bone matrix plus bone marrow clot. The enriched bone matrix plus bone marrow clot composite also was superior to the enriched bone matrix alone in fusion volume and in fusion area. These data confirm that the addition of a bone marrow clot to an enriched cell-matrix composite graft results in significant improvement in graft performance. Enriched composite grafts prepared using this strategy provide a rapid, simple, safe, and inexpensive method for intraoperative concentration and delivery of bone marrow-derived cells and connective tissue progenitors that may improve the outcome of bone grafting.
Superfund chemical data matrix, 1996
1996-06-01
The Superfund Chemical Data Matrix (SCDM) is a source for factor values and benchmark values applied when evaluating potential National Priorities List (NPL) sites using the Hazard Ranking System. The HRS assigns factor values for toxicity, gas migration potential, gas and ground water mobility, surface water persistence, and bioaccumulation potential based on the physical, chemical, and radiological properties of hazardous substances present at a site. Hazardous substances, as defined for HRS purposes, are CERCLA hazardous substances plus CERCLA pollutants and contaminants. The HRS also assigns extra weight to targets with exposure levels to hazardous substances that are at or above benchmarks. These benchmarks include both risk-based screening concentrations and concentrations specified in regulatory limits for the hazardous substances present at a site for a particular migration pathway.
Continuous analogues of matrix factorizations
Townsend, Alex; Trefethen, Lloyd N.
2015-01-01
Analogues of singular value decomposition (SVD), QR, LU and Cholesky factorizations are presented for problems in which the usual discrete matrix is replaced by a ‘quasimatrix’, continuous in one dimension, or a ‘cmatrix’, continuous in both dimensions. Two challenges arise: the generalization of the notions of triangular structure and row and column pivoting to continuous variables (required in all cases except the SVD, and far from obvious), and the convergence of the infinite series that define the cmatrix factorizations. Our generalizations of triangularity and pivoting are based on a new notion of a ‘triangular quasimatrix’. Concerning convergence of the series, we prove theorems asserting convergence provided the functions involved are sufficiently smooth. PMID:25568618
Evaluation of metal matrix composites
NASA Technical Reports Server (NTRS)
Okelly, K. P.
1971-01-01
The results of an evaluation of candidate metal-matrix composite materials for shuttle space radiators mounted to external structure are presented. The evaluation was specifically applicable to considerations of the manufacturing and properties of a potential space radiator. Two candidates, boron/aluminum and graphite/aluminum were obtained or made in various forms and tested in sufficient depth to allow selection of one of the two for future scale-up programs. The effort accomplished on this program verified that aluminum reinforced with boron was within the state-of-the-art in industry and possessed properties usable in the external skin areas available for shuttle radiators where re-entry temperatures will not exceed 800 F. It further demonstrated that graphite/aluminum has an apparently attractive future for space applications but requires extension development prior to scale-up.
Thermoplastic matrix composite processing model
NASA Technical Reports Server (NTRS)
Dara, P. H.; Loos, A. C.
1985-01-01
The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact.
Xu, Hui; Sandor, Maryellen; Lombardi, Jared
2013-01-01
Extracellular matrices derived from animal tissues for human tissue repairs are processed by various methods of physical, chemical, or enzymatic decellularization, viral inactivation, and terminal sterilization. The mechanisms of action in tissue repair vary among bioscaffolds and are suggested to be associated with process-induced extracellular matrix modifications. We compared three non-cross-linked, commercially available extracellular matrix scaffolds (Strattice, Veritas, and XenMatrix), and correlated extracellular matrix alterations to in vivo biological responses upon implantation in non-human primates. Structural evaluation showed significant differences in retaining native tissue extracellular matrix histology and ultrastructural features among bioscaffolds. Tissue processing may cause both the condensation of collagen fibers and fragmentation or separation of collagen bundles. Calorimetric analysis showed significant differences in the stability of bioscaffolds. The intrinsic denaturation temperature was measured to be 51°C, 38°C, and 44°C for Strattice, Veritas, and XenMatrix, respectively, demonstrating more extracellular matrix modifications in the Veritas and XenMatrix scaffolds. Consequently, the susceptibility to collagenase degradation was increased in Veritas and XenMatrix when compared to their respective source tissues. Using a non-human primate model, three bioscaffolds were found to elicit different biological responses, have distinct mechanisms of action, and yield various outcomes of tissue repair. Strattice permitted cell repopulation and was remodeled over 6 months. Veritas was unstable at body temperature, resulting in rapid absorption with moderate inflammation. XenMatrix caused severe inflammation and sustained immune reactions. This study demonstrates that extracellular matrix alterations significantly affect biological responses in soft tissue repair and regeneration. The data offer useful insights into the rational design of
Naik, Ganesh R; Nguyen, Hung T
2015-03-01
Surface electromyography (sEMG) is widely used in evaluating the functional status of the hand to assist in hand gesture recognition, prosthetics and rehabilitation applications. The sEMG is a noninvasive, easy to record signal of superficial muscles from the skin surface. Considering the nonstationary characteristics of sEMG, recent feature selection of hand gesture recognition using sEMG signals necessitate designers to use nonnegative matrix factorization (NMF)-based methods. This method exploits both the additive and sparse nature of signals by extracting accurate and reliable measurements of sEMG features using a minimum number of sensors. The testing has been conducted for simple and complex finger flexions using several experiments with artificial neural network classification scheme. It is shown, both by simulation and experimental studies, that the proposed algorithm is able to classify ten finger flexions (five simple and five complex finger flexions) recorded from two sEMG sensors up to 92% (95% for simple and 87% for complex flexions) accuracy. The recognition performances of simple and complex finger flexions are also validated with NMF permutation matrix analysis.
Thermophysical and Electrical Properties of Metal Matrix Composites
1979-12-01
de if necessary and identify by block number) Aluminum matrix composiles, aluminum alloy matrix composites, copper matrix composites, electrical...the various com- posites of aluminum and aluminum alloy mar-tices, copper matrix, lead matrix, magnesium matrix, nickel and nickel alloy matrices...titanium and titanium alloy matrices, tungsten matrix, and zinc matrix. Most of the data are for aluminum DD j JAN 73 1473 EDITION OF I NOV6 S IS
Fission Matrix Capability for MCNP Monte Carlo
NASA Astrophysics Data System (ADS)
Brown, Forrest; Carney, Sean; Kiedrowski, Brian; Martin, William
2014-06-01
We describe recent experience and results from implementing a fission matrix capability into the MCNP Monte Carlo code. The fission matrix can be used to provide estimates of the fundamental mode fission distribution, the dominance ratio, the eigenvalue spectrum, and higher mode forward and adjoint eigenfunctions of the fission neutron source distribution. It can also be used to accelerate the convergence of the power method iterations and to provide basis functions for higher-order perturbation theory. The higher-mode fission sources can be used in MCNP to determine higher-mode forward fluxes and tallies, and work is underway to provide higher-mode adjoint-weighted fluxes and tallies. Past difficulties and limitations of the fission matrix approach are overcome with a new sparse representation of the matrix, permitting much larger and more accurate fission matrix representations. The new fission matrix capabilities provide a significant advance in the state-of-the-art for Monte Carlo criticality calculations.
Eigenvalues properties of terms correspondences matrix
NASA Astrophysics Data System (ADS)
Bondarchuk, Dmitry; Timofeeva, Galina
2016-12-01
Vector model representations of text documents are widely used in the intelligent search. In this approach a collection of documents is represented in the form of the term-document matrix, reflecting the frequency of terms. In the latent semantic analysis the dimension of the vector space is reduced by the singular value decomposition of the term-document matrix. Authors use a matrix of terms correspondences, reflecting the relationship between the terms, to allocate a semantic core and to obtain more simple presentation of the documents. With this approach, reducing the number of terms is based on the orthogonal decomposition of the matrix of terms correspondences. Properties of singular values of the term-document matrix and eigenvalues of the matrix of terms correspondences are studied in the case when documents differ substantially in length.
Key Issues for Aerospace Applications of Ceramic Matrix Composites
NASA Technical Reports Server (NTRS)
Clinton, R. G., Jr.; Levine, S. R.
1998-01-01
Ceramic matrix composites (CMC) offer significant advantages for future aerospace applications including turbine engine and liquid rocket engine components, thermal protection systems, and "hot structures". Key characteristics which establish ceramic matrix composites as attractive and often enabling choices are strength retention at high temperatures and reduced weight relative to currently used metallics. However, due to the immaturity of this class of materials which is further compounded by the lack of experience with CMC's in the aerospace industry, there are significant challenges involved in the development and implementation of ceramic matrix composites into aerospace systems. Some of the more critical challenges are attachment and load transfer methodologies; manufacturing techniques, particularly scale up to large and thick section components; operational environment resistance; damage tolerance; durability; repair techniques; reproducibility; database availability; and the lack of validated design and analysis tools. The presentation will examine the technical issues confronting the application of ceramic matrix composites to aerospace systems and identify the key material systems having potential for substantial payoff relative to the primary requirements of light weight and reduced cost for future systems. Current programs and future research opportunities will be described in the presentation which will focus on materials and processes issues.
ANALYSIS OF A CLASSIFICATION ERROR MATRIX USING CATEGORICAL DATA TECHNIQUES.
Rosenfield, George H.; Fitzpatrick-Lins, Katherine
1984-01-01
Summary form only given. A classification error matrix typically contains tabulation results of an accuracy evaluation of a thematic classification, such as that of a land use and land cover map. The diagonal elements of the matrix represent the counts corrected, and the usual designation of classification accuracy has been the total percent correct. The nondiagonal elements of the matrix have usually been neglected. The classification error matrix is known in statistical terms as a contingency table of categorical data. As an example, an application of these methodologies to a problem of remotely sensed data concerning two photointerpreters and four categories of classification indicated that there is no significant difference in the interpretation between the two photointerpreters, and that there are significant differences among the interpreted category classifications. However, two categories, oak and cottonwood, are not separable in classification in this experiment at the 0. 51 percent probability. A coefficient of agreement is determined for the interpreted map as a whole, and individually for each of the interpreted categories. A conditional coefficient of agreement for the individual categories is compared to other methods for expressing category accuracy which have already been presented in the remote sensing literature.
Using self-assembled monolayers to model the extracellular matrix.
Mrksich, Milan
2009-03-01
The extracellular matrix is an insoluble aggregate of large proteins and glycosoaminoglycans that comprises the microenvironment of cells in tissue. The matrix displays a host of ligands that interact with cell-surface receptors to mediate the attachment and spreading of cells and regulate signaling processes. Studies of cell-matrix interactions and downstream signaling processes commonly employ substrates having an adsorbed layer of protein and are challenged by the difficulty in controlling the structure and activity of the immobilized protein. Significant effort has been directed towards the development of model substrates that present adhesion ligands in defined densities, orientations and environments. Among these approaches, self-assembled monolayers of alkanethiolates on gold offer a high level of control over the molecular structure of the surface and are well-suited to studies of cell adhesion. This review describes the design and use of monolayers for applications in cell biology, including the use of monolayers to evaluate the roles of peptide and protein ligands in cell-matrix interactions, the development of methods to pattern ligands on monolayers and applications to cell biology, the development of dynamic monolayers that can switch the activities of ligands presented to an adherent cell, and the rewiring of interactions between a cell and its substrate. These examples illustrate the flexibility inherent to monolayers for applications in cell biology.
Micromechanical Evaluation of Ceramic Matrix Composites
1991-02-01
Materials Sciences Corporation AD-A236 756 M.hM. 9 1 0513 IEIN HIfINU IIl- DTIC JUN 06 1991 MICROMECHANICAL EVALUATION OF S 0 CERAMIC MATRIX COMPOSITES C...Classification) \\() Micromechanical Evaluation of Ceramic Matrix Composites ) 12. PERSONAL AUTHOR(S) C-F. Yen, Z. Hashin, C. Laird, B.W. Rosen, Z. Wang 13a. TYPE...and strengthen the ceramic composites. In this task, various possibilities of crack propagation in unidirectional ceramic matrix composites under
Criteria for Matrix Dominated Failure
1988-02-01
8217 L . .... ... .... . !A,! A ,- -I 1. INTRODUCTION When designing adhesively bonded fibre composite repairs for metallic or comn- pwsite structutes, two...behaviour of fibre composite lauiinates [20.21,22]. * 4 2i 4| It haas aso been used to design 6dhMavely bonded repairs for cracked metallic com- ponents...several methodsearvently used for analysis of the ltnt rix dominated failure In composite nmaterial an adhesivty hankdedl joints . Particular attention has
Reconstituted asbestos matrix for fuel cells
NASA Technical Reports Server (NTRS)
Mcbryar, H.
1975-01-01
Method is described for reprocessing commercially available asbestos matrix stock to yield greater porosity and bubble pressure (due to increased surface tension), improved homogeneity, and greater uniformity.
Matrix metalloproteinases in destructive lung disease.
Houghton, A McGarry
2015-01-01
Matrix metalloproteinases (MMPs) play essential physiologic roles in numerous processes ranging from development to wound repair. Unfortunately, given the broad substrate specificity of the MMP family as a whole, aberrant degradation of extracellular matrix proteins can result in destructive disease. Emphysema, the result of destroyed lung elastin and collagen matrix, is the prototypical example of such a destructive process. More recent data has highlighted that MMPs play much more elaborate physiologic and pathophysiologic roles than simple matrix protein cleavage. Key pathophysiological roles for MMPs in emphysema will be discussed herein.
Multiscale Modeling of Ceramic Matrix Composites
NASA Technical Reports Server (NTRS)
Bednarcyk, Brett A.; Mital, Subodh K.; Pineda, Evan J.; Arnold, Steven M.
2015-01-01
Results of multiscale modeling simulations of the nonlinear response of SiC/SiC ceramic matrix composites are reported, wherein the microstructure of the ceramic matrix is captured. This micro scale architecture, which contains free Si material as well as the SiC ceramic, is responsible for residual stresses that play an important role in the subsequent thermo-mechanical behavior of the SiC/SiC composite. Using the novel Multiscale Generalized Method of Cells recursive micromechanics theory, the microstructure of the matrix, as well as the microstructure of the composite (fiber and matrix) can be captured.
SYMAT, COVAR: Test Procedures for Matrix Calculations
NASA Technical Reports Server (NTRS)
Morris, W. L.; Wiginton, C. L.; Lowell, D. K.
1972-01-01
The FORTRAN subroutine SYMAT and related subroutines are described. In essence SYMAT is an iterative algorithm in which the problem of finding eigenvalues and eigenvectors of a real symmetric matrix is transformed into an equivalent problem of finding eigenvalues and eigenvectors of an infinite sequence of matrices of order two. A DEMO PROGRAM contains a subroutine COVAR which is used to compute the covariance matrix (denoted by A) of a data matrix (denoted by X). Since a covariance matrix is symmetric it can be analyzed by using subroutine SYMAT.
Stokes scattering matrix for human skin.
Bhandari, Anak; Stamnes, Snorre; Hamre, Børge; Frette, Oyvind; Stamnes, Knut; Stamnes, Jakob J
2012-11-01
We use a layered model of normal human skin based on size distributions of polydisperse spherical particles and their complex refractive indices to compute the Stokes scattering matrix at wavelengths in the visible spectral band. The elements of the Stokes scattering matrix are required in a polarized radiative transfer code for a coupled air-tissue system to compute the polarized reflectance and examine how it is dependent on the vertical structure of the inherent optical properties of skin, including the phase matrix. Thus, the elements of the Stokes scattering matrix can be useful for investigating polarization-dependent light propagation in turbid optical media, such as human skin tissue.
NASA Technical Reports Server (NTRS)
Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Jones, Clyde S. (Technical Monitor)
2002-01-01
This presentation provides an overview of the effort by Metal Matrix Cast Composites, Inc. to redesign turbopump housing joints using metal matrix composite material and a toolless net-shape pressure infiltration casting technology. Topics covered include: advantage of metal matrix composites for propulsion components, baseline pump design and analysis, advanced toolless pressure infiltration casting process, subscale pump housing, preform splicing and joining for large components, and fullscale pump housing redesign.
Queering Participatory Design Research
ERIC Educational Resources Information Center
McWilliams, Jacob
2016-01-01
This article offers a way forward for educators and researchers interested in drawing on the principles of "queer theory" to inform participatory design. In this article, I aim to achieve two related goals: To introduce new concepts within a critical conceptual practice of questioning and challenging the "heterosexual matrix"…
Extracellular matrix proteins of dentine.
Butler, W T; Ritchie, H H; Bronckers, A L
1997-01-01
Bone and dentine extracellular matrix proteins are similar, consisting primarily of type I collagen, acidic proteins and proteoglycans. Although collagen forms the lattice for deposition of calcium and phosphate for formation of carbonate apatite, the non-collagenous proteins are believed to control initiation and growth of the crystals. Despite this similarity, dentine contains three unique proteins apparently absent from bone and other tissue: dentine phosphophoryn (DPP), dentine matrix protein 1 (DMP1) and dentine sialoprotein (DSP). DPP and DMP1 are acidic phosphoproteins probably involved in the control of mineralization processes. DPP may localize in gap regions of collagen and initiate apatite crystal formation by binding large quantities of calcium in a conformation that promotes this process. Extensive studies have been conducted in our laboratory on the nature, biosynthesis, localization and gene structure of DSP. Immunolocalization studies showed that rat DSP, a 53 kDa sialic acid-rich glycoprotein, was synthesized by young and mature odontoblasts, and by dental pulp cells and pre-ameloblasts, but not by ameloblasts, osteoblasts, chondrocytes or other cell types. The cDNA sequence indicated that DSP was a 366-residue protein with several potential N-glycosylation sites, as well as phosphorylation sites, but that the amino acid sequence was dissimilar to that of other known proteins. Northern blot analysis detected several mRNA species near 4.6 and 1.5 kb, indicative of alternative splicing events. Evidence for two DSP genes was obtained, further complicating this picture. Recent in situ hybridization studies utilizing rat and mouse molars and incisors indicated that DSP mRNA was expressed by young odontoblasts and odontoblasts in animals of all ages. Transcripts were also observed in pre-ameloblasts. The expression of DSP mRNA ceased when these cells matured to become secretory ameloblasts. DSP transcripts were not detected in osteoblasts or other cell
Extracellular matrix components in peripheral nerve regeneration.
Gonzalez-Perez, Francisco; Udina, Esther; Navarro, Xavier
2013-01-01
Injured axons of the peripheral nerve are able to regenerate and, eventually, reinnervate target organs. However, functional recovery is usually poor after severe nerve injuries. The switch of Schwann cells to a proliferative state, secretion of trophic factors, and the presence of extracellular matrix (ECM) molecules (such as collagen, laminin, or fibronectin) in the distal stump are key elements to create a permissive environment for axons to grow. In this review, we focus attention on the ECM components and their tropic role in axonal regeneration. These components can also be used as molecular cues to guide the axons through artificial nerve guides in attempts to better mimic the natural environment found in a degenerating nerve. Most used scaffolds tested are based on natural molecules that form the ECM, but use of synthetic polymers and functionalization of hydrogels are bringing new options. Progress in tissue engineering will eventually lead to the design of composite artificial nerve grafts that may replace the use of autologous nerve grafts to sustain regeneration over long gaps.
Vascular Extracellular Matrix and Arterial Mechanics
WAGENSEIL, JESSICA E.; MECHAM, ROBERT P.
2009-01-01
An important factor in the transition from an open to a closed circulatory system was a change in vessel wall structure and composition that enabled the large arteries to store and release energy during the cardiac cycle. The component of the arterial wall in vertebrates that accounts for these properties is the elastic fiber network organized by medial smooth muscle. Beginning with the onset of pulsatile blood flow in the developing aorta, smooth muscle cells in the vessel wall produce a complex extracellular matrix (ECM) that will ultimately define the mechanical properties that are critical for proper function of the adult vascular system. This review discusses the structural ECM proteins in the vertebrate aortic wall and will explore how the choice of ECM components has changed through evolution as the cardiovascular system became more advanced and pulse pressure increased. By correlating vessel mechanics with physiological blood pressure across animal species and in mice with altered vessel compliance, we show that cardiac and vascular development are physiologically coupled, and we provide evidence for a universal elastic modulus that controls the parameters of ECM deposition in vessel wall development. We also discuss mechanical models that can be used to design better tissue-engineered vessels and to test the efficacy of clinical treatments. PMID:19584318
Robust Joining and Assembly of Ceramic Matrix Composites for High Temperature Applications
NASA Technical Reports Server (NTRS)
Singh, Mrityunjay
2003-01-01
Advanced ceramic matrix composites (CMCs) are under active consideration for use in a wide variety of high temperature applications within the aerospace, energy, and nuclear industries. The engineering designs of CMC components require fabrication and manufacturing of large and complex shaped parts of various thicknesses. In many instances, it is more economical to build up complex shapes by joining simple geometrical shapes. Thus, joining and attachment have been recognized as enabling technologies for successful utilization of ceramic components in various demanding applications. In this presentation, various challenges and opportunities in design, fabrication, and testing of high temperature joints in ceramic matrix composites will be presented. A wide variety of ceramic composites, in different shapes and sizes, have been joined using an affordable, robust ceramic joining technology (ARCJoinT). Microstructure and mechanical properties of joints in melt infiltrated and CVI Sic matrix composites will be reported. Various joint design philosophies and design issues in joining of composites will be discussed.
A review of failure models for unidirectional ceramic matrix composites under monotonic loads
NASA Technical Reports Server (NTRS)
Tripp, David E.; Hemann, John H.; Gyekenyesi, John P.
1989-01-01
Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by trial and error since the emphasis of feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.
The evolution of extracellular matrix.
Ozbek, Suat; Balasubramanian, Prakash G; Chiquet-Ehrismann, Ruth; Tucker, Richard P; Adams, Josephine C
2010-12-01
We present a perspective on the molecular evolution of the extracellular matrix (ECM) in metazoa that draws on research publications and data from sequenced genomes and expressed sequence tag libraries. ECM components do not function in isolation, and the biological ECM system or "adhesome" also depends on posttranslational processing enzymes, cell surface receptors, and extracellular proteases. We focus principally on the adhesome of internal tissues and discuss its origins at the dawn of the metazoa and the expansion of complexity that occurred in the chordate lineage. The analyses demonstrate very high conservation of a core adhesome that apparently evolved in a major wave of innovation in conjunction with the origin of metazoa. Integrin, CD36, and certain domains predate the metazoa, and some ECM-related proteins are identified in choanoflagellates as predicted sequences. Modern deuterostomes and vertebrates have many novelties and elaborations of ECM as a result of domain shuffling, domain innovations and gene family expansions. Knowledge of the evolution of metazoan ECM is important for understanding how it is built as a system, its roles in normal tissues and disease processes, and has relevance for tissue engineering, the development of artificial organs, and the goals of synthetic biology.
ERIC Educational Resources Information Center
Jacobs, James A.
1994-01-01
This learning module on composites such as polymer matrix, metal matrix, ceramic matrix, particulate, and laminar includes a design brief giving context, objectives, evaluation, student outcomes, and quiz. (SK)
[The speech audiometry using the matrix sentence test].
Boboshko, M Yu; Zhilinskaya, E V; Vazhybok, A; Mal'tseva, N V; Tsokol', M; Kol'meier, B
The matrix sentence test in which the five-word semantically unpredictable sentences presented under the background noise conditions are used as the speech material was designed and validated for many languages. The objective of the present study was to evaluate the Russian version of the matrix sentence test (RuMatrix test) in the listeners of different ages with normal hearing. At the first stage of the study, 35 listeners at the age from 18 to 33 year were examined. The results of the estimation of the training effect dictated the necessity of conducting two training tracks before carrying out the RuMatrix test proper. The signal-to-noise ratio at which 50% speech recognition (SRT50) was obtained was found to be -8.8±0.8 dB SNR. A significant effect of exposure to the background noise was demonstrated: the noise level of 80 and 75 Db SPL led to a considerably lower intelligibility than the noise levels in the range from 45 to 70 dB SPL; in the subsequent studies, the noise level of 65 dB SPL was used. The high test-retest reliability of the RuMatrix test was proved. At the second stage of the study, 20 young (20-40 year old) listeners and 20 aged (62-74 year old) ones were examined. The mean SRT50 in the aged patients was found to be -6.9±1.1 dB SNR which was much worse than the mean STR50 in the young subjects (-8.7±0.9 dB SNR). It is concluded that, bearing in mind the excellent comparability of the results of the RUMat rix test across different languages, it can be used as a universal tool in international research projects.
Matrix model description of baryonic deformations
Bena, Iosif; Murayama, Hitoshi; Roiban, Radu; Tatar, Radu
2003-03-13
We investigate supersymmetric QCD with N{sub c} + 1 flavors using an extension of the recently proposed relation between gauge theories and matrix models.The impressive agreement between the two sides provides a beautiful confirmation of the extension of the gauge theory-matrix model relation to this case.
Improvements in sparse matrix operations of NASTRAN
NASA Technical Reports Server (NTRS)
Harano, S.
1980-01-01
A "nontransmit" packing routine was added to NASTRAN to allow matrix data to be refered to directly from the input/output buffer. Use of the packing routine permits various routines for matrix handling to perform a direct reference to the input/output buffer if data addresses have once been received. The packing routine offers a buffer by buffer backspace feature for efficient backspacing in sequential access. Unlike a conventional backspacing that needs twice back record for a single read of one record (one column), this feature omits overlapping of READ operation and back record. It eliminates the necessity of writing, in decomposition of a symmetric matrix, of a portion of the matrix to its upper triangular matrix from the last to the first columns of the symmetric matrix, thus saving time for generating the upper triangular matrix. Only a lower triangular matrix must be written onto the secondary storage device, bringing 10 to 30% reduction in use of the disk space of the storage device.
The Molecules of the Cell Matrix.
ERIC Educational Resources Information Center
Weber, Klaus; Osborn, Mary
1985-01-01
Cytoplasmic proteins form a highly structured yet changeable matrix that affects cell shape, division, motion, and transport of vesicles and organelles. Types of microfilaments, research techniques, actin and myosin, tumor cells, and other topics are addressed. Evidence indicates that the cell matrix might have a bearing on metabolism. (DH)
Risk Management using Dependency Stucture Matrix
NASA Astrophysics Data System (ADS)
Petković, Ivan
2011-09-01
An efficient method based on dependency structure matrix (DSM) analysis is given for ranking risks in a complex system or process whose entities are mutually dependent. This rank is determined according to the element's values of the unique positive eigenvector which corresponds to the matrix spectral radius modeling the considered engineering system. For demonstration, the risk problem of NASA's robotic spacecraft is analyzed.
Combination detergent/MALDI matrix: functional cleavable detergents for mass spectrometry.
Norris, Jeremy L; Porter, Ned A; Caprioli, Richard M
2005-08-01
This study reports the synthesis of the first functional cleavable detergent designed specifically for applications in mass spectrometry. Upon cleavage, two inert compounds and the MALDI matrix are formed, eliminating sources of potential interference originating from traditional cleavable detergents. Analysis of peptides demonstrates that MALDI matrix generated in situ results in MALDI spectra equivalent to those prepared using established protocols. Analysis of the membrane protein diacylglycerol kinase was accomplished using the combination detergent/MALDI matrix. Applications of the functional cleavable detergents to the profiling of whole cell lysates results in increased signal-to-noise ratios of many ions and the detection of additional proteins previously not observed.
BD Hanson; J Abrefah; SC Marschman; SG Prussin
2000-09-08
The main objective of this project is to develop an advanced fuel matrix capable of achieving extended burnup while improving safety margins and reliability for present operations. In the course of this project, the authors improve understanding of the mechanism for high burnup structure (HBS) formation and attempt to design a fuel to minimize its formation. The use of soluble dopants in the UO{sub 2} matrix to stabilize the matrix and minimize fuel-side corrosion of the cladding is the main focus.
ERIC Educational Resources Information Center
Anuar, Azad Athahiri; Rozubi, Norsayyidatina Che; Abdullah, Haslee Sharil
2015-01-01
The aims of this study were to develop and validate a MCC training module for trainee counselor based on MCC matrix model by Sue et al. (1992). This module encompassed five sub modules and 11 activities developed along the concepts and components of the MCC matrix model developed by Sue, Arredondo dan McDavis (1992). The design method used in this…
Control and synchronizing nonlinear systems with delay based on a special matrix structure
NASA Astrophysics Data System (ADS)
Hu, Jianbing; Zhao, Lingdong; Xie, Zhenguang
2014-04-01
This work presents a direct approach to design stabilizing controller for nonlinear systems with delay based on a special matrix structure and proves the validity of the approach according to Lyapunov-Krasovskii stable theorem and Linear Matrix Inequality—LMI. Control Lorenz system and synchronizing Rössler system with delay are taken as examples to explain the approach. Numerical simulations confirm the effectiveness of the approach proposed.
Maximizing sparse matrix vector product performance in MIMD computers
McLay, R.T.; Kohli, H.S.; Swift, S.L.; Carey, G.F.
1994-12-31
A considerable component of the computational effort involved in conjugate gradient solution of structured sparse matrix systems is expended during the Matrix-Vector Product (MVP), and hence it is the focus of most efforts at improving performance. Such efforts are hindered on MIMD machines due to constraints on memory, cache and speed of memory-cpu data transfer. This paper describes a strategy for maximizing the performance of the local computations associated with the MVP. The method focuses on single stride memory access, and the efficient use of cache by pre-loading it with data that is re-used while bypassing it for other data. The algorithm is designed to behave optimally for varying grid sizes and number of unknowns per gridpoint. Results from an assembly language implementation of the strategy on the iPSC/860 show a significant improvement over the performance using FORTRAN.
Noncoherent matrix inversion methods for Scansar processing
NASA Astrophysics Data System (ADS)
Dendal, Didier
1995-11-01
The aim of this work is to develop some algebraic reconstruction techniques for low resolution power SAR imagery, as in the Scansar or QUICKLOOK imaging modes. The traditional reconstruction algorithms are indeed not well fit to low resolution power purposes, since Fourier constraints impose a computational load of the same order as the one of the usual SAR azimuthal resolution. Furthermore, the range migration balancing is superfluous, as it does not cover a tenth of the resolution cell in the less favorable situations. There are several possibilities for using matrices in the azimuthal direction. The most direct alternative leads to a matrix inversion. Unfortunately, the numerical conditioning of the problem is far from being excellent, since each line of the matrix is an image of the antenna radiating pattern with a shift between two successive lines corresponding to the distance covered by the SAR between two pulses transmission (a few meters for satellite ERS1). We'll show how it is possible to turn a very ill conditioned problem into an equivalent one, but without any divergence risk, by a technique of successive decimation by two (resolution power increased by two at each step). This technique leads to very small square matrices (two lines and two columns), the good numeric conditioning of which is certified by a well-known theorem of numerical analysis. The convergence rate of the process depends on the circumstances (mainly the distance between two impulses transmissions) and on the required accuracy, but five or six iterations already give excellent results. The process is applicable at four or five levels (number of decimations) which corresponds to initial matrices of 16 by 16 or 32 by 32. The azimuth processing is performed on the basis of the projection function concept (tomographic analogy of radar principles). This integrated information results from classical coherent range compression. The aperture synthesis is obtained by non-coherent processing
Block Hadamard measurement matrix with arbitrary dimension in compressed sensing
NASA Astrophysics Data System (ADS)
Liu, Shaoqiang; Yan, Xiaoyan; Fan, Xiaoping; Li, Fei; Xu, Wen
2017-01-01
As Hadamard measurement matrix cannot be used for compressing signals with dimension of a non-integral power-of-2, this paper proposes a construction method of block Hadamard measurement matrix with arbitrary dimension. According to the dimension N of signals to be measured, firstly, construct a set of Hadamard sub matrixes with different dimensions and make the sum of these dimensions equals to N. Then, arrange the Hadamard sub matrixes in a certain order to form a block diagonal matrix. Finally, take the former M rows of the block diagonal matrix as the measurement matrix. The proposed measurement matrix which retains the orthogonality of Hadamard matrix and sparsity of block diagonal matrix has highly sparse structure, simple hardware implements and general applicability. Simulation results show that the performance of our measurement matrix is better than Gaussian matrix, Logistic chaotic matrix, and Toeplitz matrix.
The matrix exponential in transient structural analysis
NASA Technical Reports Server (NTRS)
Minnetyan, Levon
1987-01-01
The primary usefulness of the presented theory is in the ability to represent the effects of high frequency linear response with accuracy, without requiring very small time steps in the analysis of dynamic response. The matrix exponential contains a series approximation to the dynamic model. However, unlike the usual analysis procedure which truncates the high frequency response, the approximation in the exponential matrix solution is in the time domain. By truncating the series solution to the matrix exponential short, the solution is made inaccurate after a certain time. Yet, up to that time the solution is extremely accurate, including all high frequency effects. By taking finite time increments, the exponential matrix solution can compute the response very accurately. Use of the exponential matrix in structural dynamics is demonstrated by simulating the free vibration response of multi degree of freedom models of cantilever beams.
Biocompatible 3D Matrix with Antimicrobial Properties.
Ion, Alberto; Andronescu, Ecaterina; Rădulescu, Dragoș; Rădulescu, Marius; Iordache, Florin; Vasile, Bogdan Ștefan; Surdu, Adrian Vasile; Albu, Madalina Georgiana; Maniu, Horia; Chifiriuc, Mariana Carmen; Grumezescu, Alexandru Mihai; Holban, Alina Maria
2016-01-20
The aim of this study was to develop, characterize and assess the biological activity of a new regenerative 3D matrix with antimicrobial properties, based on collagen (COLL), hydroxyapatite (HAp), β-cyclodextrin (β-CD) and usnic acid (UA). The prepared 3D matrix was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Microscopy (FT-IRM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). In vitro qualitative and quantitative analyses performed on cultured diploid cells demonstrated that the 3D matrix is biocompatible, allowing the normal development and growth of MG-63 osteoblast-like cells and exhibited an antimicrobial effect, especially on the Staphylococcus aureus strain, explained by the particular higher inhibitory activity of usnic acid (UA) against Gram positive bacterial strains. Our data strongly recommend the obtained 3D matrix to be used as a successful alternative for the fabrication of three dimensional (3D) anti-infective regeneration matrix for bone tissue engineering.
Fiber-matrix interfaces in ceramic composites
Besmann, T.M.; Stinton, D.P.; Kupp, E.R.; Shanmugham, S.; Liaw, P.K.
1996-12-31
The mechanical properties of ceramic matrix composites (CMCs) are governed by the relationships between the matrix, the interface material, and the fibers. In non-oxide matrix systems compliant pyrolytic carbon and BN have been demonstrated to be effective interface materials, allowing for absorption of mismatch stresses between fiber and matrix and offering a poorly bonded interface for crack deflection. The resulting materials have demonstrated remarkable strain/damage tolerance together with high strength. Carbon or BN, however, suffer from oxidative loss in many service environments, and thus there is a major search for oxidation resistant alternatives. This paper reviews the issues related to developing a stable and effective interface material for non-oxide matrix CMCs.
Nuclear Matrix Proteins in Human Colon Cancer
NASA Astrophysics Data System (ADS)
Keesee, Susan K.; Meneghini, Marc D.; Szaro, Robert P.; Wu, Ying-Jye
1994-03-01
The nuclear matrix is the nonchromatin scaffolding of the nucleus. This structure confers nuclear shape, organizes chromatin, and appears to contain important regulatory proteins. Tissue specific nuclear matrix proteins have been found in the rat, mouse, and human. In this study we compared high-resolution two-dimensional gel electropherograms of nuclear matrix protein patterns found in human colon tumors with those from normal colon epithelia. Tumors were obtained from 18 patients undergoing partial colectomy for adenocarcinoma of the colon and compared with tissue from 10 normal colons. We have identified at least six proteins which were present in 18 of 18 colon tumors and 0 of 10 normal tissues, as well as four proteins present in 0 of 18 tumors and in 10 of 10 normal tissues. These data, which corroborate similar findings of cancer-specific nuclear matrix proteins in prostate and breast, suggest that nuclear matrix proteins may serve as important markers for at least some types of cancer.
A matrix analysis of conjugate gradient algorithms
Ashby, S.F.; Gutknecht, M.H.
1993-04-01
This paper explores the relationships between the conjugate gradient algorithms Orthodir, Orthomin, and Orthores. To facilitate this exploration, a matrix formulation for each algorithm is given. It is shown that Orthodir directly computes a Hessenberg matrix H{sub k} at step k. Orthores also computes a Hessenberg matrix, G{sub k}, which is similar to a Hessenberg matrix obtained from H{sub k} by perturbing its last column. (This perturbation vanishes at convergence.) Orthomin, on the other hand, computes a UL and LU factorization of the perturbed H{sub k} and G{sub k}, respectively. The breakdown of Orthomin and Orthores are interpreted in terms of these underlying matrix factorizations. A connection with Lanczos algorithms is also examined, as is the special case of B-normal(1) matrices (for which efficient three-term CG algorithms exist).
Instruments for Reading Direct-Marked Data-Matrix Symbols
NASA Technical Reports Server (NTRS)
Schramm, Harry F.; Corder, Eric L.
2006-01-01
Improved optoelectronic instruments (specially configured digital cameras) for reading direct-marked data-matrix symbols on the surfaces of optically reflective objects (including specularly reflective ones) are undergoing development. Data-matrix symbols are two-dimensional binary patterns that are used, like common bar codes, for automated identification of objects. The first data-matrix symbols were checkerboard-like patterns of black-and-white rectangles, typically existing in the forms of paint, ink, or detachable labels. The major advantage of direct marking (the marks are more durable than are painted or printed symbols or detachable labels) is offset by a major disadvantage (the marks generated by some marking methods do not provide sufficient contrast to be readable by optoelectronic instruments designed to read black-and-white data-matrix symbols). Heretofore, elaborate lighting, lensing, and software schemes have been tried in efforts to solve the contrast problem in direct-mark matrix- symbol readers. In comparison with prior readers based on those schemes, the readers now undergoing development are expected to be more effective while costing less. All of the prior direct-mark matrix-symbol readers are designed to be aimed perpendicularly to marked target surfaces, and they tolerate very little angular offset. However, the reader now undergoing development not only tolerates angular offset but depends on angular offset as a means of obtaining the needed contrast, as described below. The prototype reader (see Figure 1) includes an electronic camera in the form of a charge-coupled-device (CCD) image detector equipped with a telecentric lens. It also includes a source of collimated visible light and a source of collimated infrared light for illuminating a target. The visible and infrared illumination complement each other: the visible illumination is more useful for aiming the reader toward a target, while the infrared illumination is more useful for
Optimal control concepts in design sensitivity analysis
NASA Technical Reports Server (NTRS)
Belegundu, Ashok D.
1987-01-01
A close link is established between open loop optimal control theory and optimal design by noting certain similarities in the gradient calculations. The resulting benefits include a unified approach, together with physical insights in design sensitivity analysis, and an efficient approach for simultaneous optimal control and design. Both matrix displacement and matrix force methods are considered, and results are presented for dynamic systems, structures, and elasticity problems.
MATRIX City: A Multi-Risk Platform
NASA Astrophysics Data System (ADS)
Euchner, F.; Mignan, A.
2012-04-01
MATRIX City (the MATRIX Common IT sYstem) is the computational platform that is being developed in the course of the New Multi-Hazard and Multi-Risk Assessment Methods for Europe (MATRIX) project. MATRIX aims to develop multi-type hazard and risk assessment and mitigation tools suited to the European context. The core of MATRIX City is a risk engine of a novel type that is based on a sequential simulation approach, which allows to quantify interactions and other time-dependent processes at the hazard, exposure, vulnerability and risk levels. For risk estimation in realistic scenarios, data availability is crucial. To overcome this limitation, MATRIX City provides a component called Virtual City. It is a collection of heuristic databases, which provides a generic approach to quantifying multi-type hazard and risk when data coverage is poor, and for sensitivity analysis. MATRIX City results are intended to provide a "big picture" of the expected impact of multi-type hazard and risk modelling (as opposed to static modelling), thus being a valuable tool for decision support. MATRIX City development uses a modern software engineering approach (test-driven development, continuous integration). The architecture is flexible, so that new perils, new models and large datasets can be accommodated easily. However, it should be noted that hazard computation is not part of MATRIX City. Hazard footprints have to be provided as input data, as well as exposure and vulnerability. The data model used in MATRIX City is an enhancement of the Natural hazards' Risk Markup Language (NRML). An XML serialization of this data model, which is a GML (Geographic Markup Language) application schema, is used for data interchange.
Creep of plain weave polymer matrix composites
NASA Astrophysics Data System (ADS)
Gupta, Abhishek
Polymer matrix composites are increasingly used in various industrial sectors to reduce structural weight and improve performance. Woven (also known as textile) composites are one class of polymer matrix composites with increasing market share mostly due to their lightweight, their flexibility to form into desired shape, their mechanical properties and toughness. Due to the viscoelasticity of the polymer matrix, time-dependent degradation in modulus (creep) and strength (creep rupture) are two of the major mechanical properties required by engineers to design a structure reliably when using these materials. Unfortunately, creep and creep rupture of woven composites have received little attention by the research community and thus, there is a dire need to generate additional knowledge and prediction models, given the increasing market share of woven composites in load bearing structural applications. Currently, available creep models are limited in scope and have not been validated for any loading orientation and time period beyond the experimental time window. In this thesis, an analytical creep model, namely the Modified Equivalent Laminate Model (MELM), was developed to predict tensile creep of plain weave composites for any orientation of the load with respect to the orientation of the fill and warp fibers, using creep of unidirectional composites. The ability of the model to predict creep for any orientation of the load is a "first" in this area. The model was validated using an extensive experimental involving the tensile creep of plain weave composites under varying loading orientation and service conditions. Plain weave epoxy (F263)/ carbon fiber (T300) composite, currently used in aerospace applications, was procured as fabrics from Hexcel Corporation. Creep tests were conducted under two loading conditions: on-axis loading (0°) and off-axis loading (45°). Constant load creep, in the temperature range of 80-240°C and stress range of 1-70% UTS of the
Planned Missing Data Designs in Psychological Research
ERIC Educational Resources Information Center
Graham, John W.; Taylor, Bonnie J.; Olchowski, Allison E.; Cumsille, Patricio E.
2006-01-01
The authors describe 2 efficiency (planned missing data) designs for measurement: the 3-form design and the 2-method measurement design. The 3-form design, a kind of matrix sampling, allows researchers to leverage limited resources to collect data for 33% more survey questions than can be answered by any 1 respondent. Power tables for estimating…
Matrix evaluation of science objectives
NASA Technical Reports Server (NTRS)
Wessen, Randii R.
1994-01-01
The most fundamental objective of all robotic planetary spacecraft is to return science data. To accomplish this, a spacecraft is fabricated and built, software is planned and coded, and a ground system is designed and implemented. However, the quantitative analysis required to determine how the collection of science data drives ground system capabilities has received very little attention. This paper defines a process by which science objectives can be quantitatively evaluated. By applying it to the Cassini Mission to Saturn, this paper further illustrates the power of this technique. The results show which science objectives drive specific ground system capabilities. In addition, this process can assist system engineers and scientists in the selection of the science payload during pre-project mission planning; ground system designers during ground system development and implementation; and operations personnel during mission operations.
Imide Modified Epoxy Matrix Resin.
1981-02-01
the bisimide amine cured epoxies (IME’s) were considerably lower than the state-of-the-art epoxies . The strain-to-failure of the control resin system ...nine epoxy resin systems which were prepared from tetraglycidyl methylenedianiline (MY 720) cured with a stoichiometric quantity of bisimide-amine and...graphite imide modified cured epoxy resin composites. The designation for each material is also listed in Table 1. The composition of each resin system
Hierarchical cluster analysis of matrix effects on 110 pesticide residues in 28 tea matrixes.
Li, Yan; Pang, Guo-Fang; Fan, Chun-Lin; Chen, Xi
2013-01-01
Matrix effects on 110 pesticides in 28 tea matrixes of different varieties and origins by LC/MS/MS were studied, and most of the pesticides exhibited soft and medium signal suppression. To better understand the influence of the tea varieties and the physicochemical characteristics of pesticides on the matrix effects, the multivariate analysis tool called hierarchical cluster analysis was applied. Tea matrixes were grouped into three clusters: unfermented, fermented, and post-fermented teas. Any type of tea can be chosen from each cluster as a corresponding representative matrix within that cluster to make matrix-matched solutions, which could simplify analysis while guaranteeing its accuracy. Matrix effects on most pesticides were similar despite the physicochemical diversities of the pesticides.
Decellularized bone matrix grafts for calvaria regeneration
Lee, Dong Joon; Diachina, Shannon; Lee, Yan Ting; Zhao, Lixing; Zou, Rui; Tang, Na; Han, Han; Chen, Xin; Ko, Ching-Chang
2016-01-01
Decellularization is a promising new method to prepare natural matrices for tissue regeneration. Successful decellularization has been reported using various tissues including skin, tendon, and cartilage, though studies using hard tissue such as bone are lacking. In this study, we aimed to define the optimal experimental parameters to decellularize natural bone matrix using 0.5% sodium dodecyl sulfate and 0.1% NH4OH. Then, the effects of decellularized bone matrix on rat mesenchymal stem cell proliferation, osteogenic gene expression, and osteogenic differentiations in a two-dimensional culture system were investigated. Decellularized bone was also evaluated with regard to cytotoxicity, biochemical, and mechanical characteristics in vitro. Evidence of complete decellularization was shown through hematoxylin and eosin staining and DNA measurements. Decellularized bone matrix displayed a cytocompatible property, conserved structure, mechanical strength, and mineral content comparable to natural bone. To study new bone formation, implantation of decellularized bone matrix particles seeded with rat mesenchymal stem cells was conducted using an orthotopic in vivo model. After 3 months post-implantation into a critical-sized defect in rat calvaria, new bone was formed around decellularized bone matrix particles and also merged with new bone between decellularized bone matrix particles. New bone formation was analyzed with micro computed tomography, mineral apposition rate, and histomorphometry. Decellularized bone matrix stimulated mesenchymal stem cell proliferation and osteogenic differentiation in vitro and in vivo, achieving effective bone regeneration and thereby serving as a promising biological bone graft. PMID:28228929
[Modern polymers in matrix tablets technology].
Zimmer, Łukasz; Kasperek, Regina; Poleszak, Ewa
2014-01-01
Matrix tablets are the most popular method of oral drug administration, and polymeric materials have been used broadly in matrix formulations to modify and modulate drug release rate. The main goal of the system is to extend drug release profiles to maintain a constant in vivo plasma drug concentration and a consistent pharmacological effect. Polymeric matrix tablets offer a great potential as oral controlled drug delivery systems. Cellulose derivatives, like hydroxypropyl methylcellulose (HPMC) are often used as matrix formers. However, also other types of polymers can be used for this purpose including: Kollidon SR, acrylic acid polymers such as Eudragits and Carbopols. Nevertheless, polymers of natural origin like: carragens, chitosan and alginates widely used in the food and cosmetics industry are now coming to the fore of pharmaceutical research and are used in matrix tablets technology. Modern polymers allow to obtain matrix tablets by 3D printing, which enables to develop new formulation types. In this paper, the polymers used in matrix tablets technology and examples of their applications were described.
Fabric analysis of Allende matrix using EBSD
NASA Astrophysics Data System (ADS)
Watt, Lauren E.; Bland, Phil A.; Prior, Dave J.; Russell, Sara S.
Fabric analysis of the interstitial matrix material in primitive meteorites offers a novel window on asteroid formation and evolution. Electron backscatter diffraction (EBSD) has allowed fabrics in these fine-grained materials to be visualized in detail for the first time. Our data reveal that Allende, a CV3 chondrite, possesses a uniform, planar, short-axis alignment fabric that is pervasive on a broad scale and is probably the result of deformational shortening related to impact or gravitational compaction. Interference between this matrix fabric and the larger, more rigid components, such as dark inclusions (DIs) and calcium-aluminium-rich inclusions (CAIs), has lead to the development of locally oriented and intensified matrix fabrics. In addition, DIs possess fabrics that are conformable with the broader matrix fabric. These results suggest that DIs were in situ prior to the deformational shortening event responsible for these fabrics, thus providing an argument against dark inclusions being fragments from another lithified part of the asteroid (Kojima and Tomeoka 1996; Fruland et al. 1978). Moreover, both DIs and Allende matrix are highly porous (˜25%) (Corrigan et al. 1997). Mobilizing a highly porous DI during impact-induced brecciation without imposing a fabric and incorporating it into a highly porous matrix without significantly compacting these materials is improbable. We favor a model that involves Allende DIs, CAIs, and matrix accreting together and experiencing the same deformation events.
2-Adic clustering of the PAM matrix.
Khrennikov, A Yu; Kozyrev, S V
2009-12-07
In this paper we demonstrate that the use of the system of 2-adic numbers provides a new insight to some problems of genetics, in particular, degeneracy of the genetic code and the structure of the PAM matrix in bioinformatics. The 2-adic distance is an ultrametric and applications of ultrametric in bioinformatics are not surprising. However, by using the 2-adic numbers we match ultrametric with a number theoretic structure. In this way we find new applications of an ultrametric which differ from known up to now in bioinformatics. We obtain the following results. We show that the PAM matrix A allows the expansion into the sum of the two matrices A=A((2))+A((infinity)), where the matrix A((2)) is 2-adically regular (i.e. matrix elements of this matrix are close to locally constant with respect to the discussed earlier by the authors 2-adic parametrization of the genetic code), and the matrix A((infinity)) is sparse. We discuss the structure of the matrix A((infinity)) in relation to the side chain properties of the corresponding amino acids. We introduce the family of substitution matrices A(alpha,beta)=alpha A((2))+beta A((infinity)), alpha,beta>or=0 which should allow to vary the alignment procedure in order to take into account the different chemical and geometric properties of the amino acids.
An ESS maximum principle for matrix games.
Vincent, T L; Cressman, R
2000-11-01
Previous work has demonstrated that for games defined by differential or difference equations with a continuum of strategies, there exists a G-function, related to individual fitness, that must take on a maximum with respect to a virtual variable v whenever v is one of the vectors in the coalition of vectors which make up the evolutionarily stable strategy (ESS). This result, called the ESS maximum principle, is quite useful in determining candidates for an ESS. This principle is reformulated here, so that it may be conveniently applied to matrix games. In particular, we define a matrix game to be one in which fitness is expressed in terms of strategy frequencies and a matrix of expected payoffs. It is shown that the G-function in the matrix game setting must again take on a maximum value at all the strategies which make up the ESS coalition vector. The reformulated maximum principle is applicable to both bilinear and nonlinear matrix games. One advantage in employing this principle to solve the traditional bilinear matrix game is that the same G-function is used to find both pure and mixed strategy solutions by simply specifying an appropriate strategy space. Furthermore we show how the theory may be used to solve matrix games which are not in the usual bilinear form. We examine in detail two nonlinear matrix games: the game between relatives and the sex ratio game. In both of these games an ESS solution is determined. These examples not only illustrate the usefulness of this approach to finding solutions to an expanded class of matrix games, but aids in understanding the nature of the ESS as well.
Micromechanics-Based Computational Simulation of Ceramic Matrix Composites
NASA Technical Reports Server (NTRS)
Murthy, Pappu L. N.; Mutal, Subodh K.; Duff, Dennis L. (Technical Monitor)
2003-01-01
Advanced high-temperature Ceramic Matrix Composites (CMC) hold an enormous potential for use in aerospace propulsion system components and certain land-based applications. However, being relatively new materials, a reliable design properties database of sufficient fidelity does not yet exist. To characterize these materials solely by testing is cost and time prohibitive. Computational simulation then becomes very useful to limit the experimental effort and reduce the design cycle time, Authors have been involved for over a decade in developing micromechanics- based computational simulation techniques (computer codes) to simulate all aspects of CMC behavior including quantification of scatter that these materials exhibit. A brief summary/capability of these computer codes with typical examples along with their use in design/analysis of certain structural components is the subject matter of this presentation.
Curvature and gravity actions for matrix models
NASA Astrophysics Data System (ADS)
Blaschke, Daniel N.; Steinacker, Harold
2010-08-01
We show how gravitational actions, in particular the Einstein-Hilbert action, can be obtained from additional terms in Yang-Mills matrix models. This is consistent with recent results on induced gravitational actions in these matrix models, realizing spacetime as four-dimensional brane solutions. It opens up the possibility for a controlled non-perturbative description of gravity through simple matrix models, with interesting perspectives for the problem of vacuum energy. The relation with UV/IR mixing and non-commutative gauge theory is discussed.
Extracellular matrix signaling in morphogenesis and repair.
Clause, Kelly C; Barker, Thomas H
2013-10-01
The extracellular matrix (ECM) is critically important for many cellular processes including growth, differentiation, survival, and morphogenesis. Cells remodel and reshape the ECM by degrading and reassembling it, playing an active role in sculpting their surrounding environment and directing their own phenotypes. Both mechanical and biochemical molecules influence ECM dynamics in multiple ways; by releasing small bioactive signaling molecules, releasing growth factors stored within the ECM, eliciting structural changes to matrix proteins which expose cryptic sites and by degrading matrix proteins directly. The dynamic reciprocal communication between cells and the ECM plays a fundamental roll in tissue development, homeostasis, and wound healing.
Visual Matrix Clustering of Social Networks
Wong, Pak C.; Mackey, Patrick S.; Foote, Harlan P.; May, Richard A.
2013-07-01
The prevailing choices to graphically represent a social network in today’s literature are a node-link graph layout and an adjacency matrix. Both visualization techniques have unique strengths and weaknesses when applied to different domain applications. In this article, we focus our discussion on adjacency matrix and how to turn the matrix-based visualization technique from merely showing pairwise associations among network actors (or graph nodes) to depicting clusters of a social network. We also use node-link layouts to supplement the discussion.
Scattering matrix theory for stochastic scalar fields.
Korotkova, Olga; Wolf, Emil
2007-05-01
We consider scattering of stochastic scalar fields on deterministic as well as on random media, occupying a finite domain. The scattering is characterized by a generalized scattering matrix which transforms the angular correlation function of the incident field into the angular correlation function of the scattered field. Within the accuracy of the first Born approximation this matrix can be expressed in a simple manner in terms of the scattering potential of the scatterer. Apart from determining the angular distribution of the spectral intensity of the scattered field, the scattering matrix makes it possible also to determine the changes in the state of coherence of the field produced on scattering.
A matrix model from string field theory
NASA Astrophysics Data System (ADS)
Zeze, Syoji
2016-09-01
We demonstrate that a Hermitian matrix model can be derived from level truncated open string field theory with Chan-Paton factors. The Hermitian matrix is coupled with a scalar and U(N) vectors which are responsible for the D-brane at the tachyon vacuum. Effective potential for the scalar is evaluated both for finite and large N. Increase of potential height is observed in both cases. The large N matrix integral is identified with a system of N ZZ branes and a ghost FZZT brane.
Reducibility of Matrix Equations Containing Several Parameters.
1981-12-01
AD-AI15 568 AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOO;-ETC EF G 12 1ADA1551 REDUCIBILITY OF MATRIX EQUATIONS CONTAINING SEVERAL...PARAMETERS.E U)CA E UNCLASSIFIED AFIT/GE/RA/81D-1 N P11111111II soonhh Eu;o I. ’Trm * a, ~t- NMI 4 i’- 00Nt. met r~ REDUCIBILITY OF MATRIX EQUATIONS CONTAINING...1 REDUCIBILITY OF MATRIX EQUATIONS CONTAINING SEVERAL PARAMETERS THESIS Presented to the Faculty of the School of Engineering of the Air Force
Generic construction of efficient matrix product operators
NASA Astrophysics Data System (ADS)
Hubig, C.; McCulloch, I. P.; Schollwöck, U.
2017-01-01
Matrix product operators (MPOs) are at the heart of the second-generation density matrix renormalization group (DMRG) algorithm formulated in matrix product state language. We first summarize the widely known facts on MPO arithmetic and representations of single-site operators. Second, we introduce three compression methods (rescaled SVD, deparallelization, and delinearization) for MPOs and show that it is possible to construct efficient representations of arbitrary operators using MPO arithmetic and compression. As examples, we construct powers of a short-ranged spin-chain Hamiltonian, a complicated Hamiltonian of a two-dimensional system and, as proof of principle, the long-range four-body Hamiltonian from quantum chemistry.
Embedded systems for controlling LED matrix displays
NASA Astrophysics Data System (ADS)
Marghescu, Cristina; Drumea, Andrei
2016-12-01
LED matrix displays are a common presence in everyday life - they can be found in trains, buses, tramways, office information tables or outdoor media. The structure of the display unit is similar for all these devices, a matrix of light emitting diodes coupled between row and column lines, but there are many options for the display controller that switches these lines. Present paper analyzes different types of embedded systems that can control the LED matrix, based on single board computers, on microcontrollers with different peripheral devices or with programmable logic devices like field programmable gate arrays with implemented soft processor cores. Scalability, easiness of implementation and costs are analyzed for all proposed solutions.
Learned fusion operators based on matrix completion
NASA Astrophysics Data System (ADS)
Risko, Kelly K. D.; Hester, Charles F.
2011-05-01
The efficient and timely management of imagery captured in the battlefield requires methods capable of searching the voluminous databases and extracting highly symbolic concepts. When processing images, a semantic and definition gap exists between machine representations and the user's language. Based on matrix completion techniques, we present a fusion operator that fuses imagery and expert knowledge provided by user inputs during post analysis. Specifically, an information matrix is formed from imagery and a class map as labeled by an expert. From this matrix an image operator is derived for the extraction/prediction of information from future imagery. We will present results using this technique on single mode data.
High-temperature polymer matrix composites
NASA Technical Reports Server (NTRS)
Meador, Michael A.
1990-01-01
Polymers research at the NASA Lewis Research Center has produced high-temperature, easily processable resin systems, such as PMR-15. In addition, the Polymers Branch has investigated ways to improve the mechanical properties of polymers and the microcracking resistance of polymer matrix composites in response to industry need for new and improved aeropropulsion materials. Current and future research in the Polymers Branch is aimed at advancing the upper use temperature of polymer matrix composites to 700 F and beyond by developing new resins, by examining the use of fiber reinforcements other than graphite, and by developing coatings for polymer matrix composites to increase their oxidation resistance.
Bilateral kidney matrix stones: a rare case
Lahyani, Mounir; Rhannam, Yassine; Slaoui, Amine; Touzani, Alae; Karmouni, Tarik; Elkhader, Khalid; Koutani, Abdellatif; Andaloussi, Ahmed Ibn attya
2016-01-01
Kedney matrix stones are a rare form of calculi. Flank pain and urinary tract infections (UTI) are the most common presentations of matrix calculi. The diagnosis is usually made at surgery, but some preoperative radiographic findings might be suggestive. Open surgery was the method of choice for treatment. However, combination of ureterorenoscopy and percutaneous nephrolithotomy (PCNL) was found to be safe and effective. We report a rare case of renal and ureteral matrix stones that were diagnosed and treated by open surgery. We also describe its clinical, radiological and therapeutic features through a review of the literature. PMID:28292065
A transilient matrix for moist convection
Romps, D.; Kuang, Z.
2011-08-15
A method is introduced for diagnosing a transilient matrix for moist convection. This transilient matrix quantifies the nonlocal transport of air by convective eddies: for every height z, it gives the distribution of starting heights z{prime} for the eddies that arrive at z. In a cloud-resolving simulation of deep convection, the transilient matrix shows that two-thirds of the subcloud air convecting into the free troposphere originates from within 100 m of the surface. This finding clarifies which initial height to use when calculating convective available potential energy from soundings of the tropical troposphere.
Taking correlations in GPS least squares adjustments into account with a diagonal covariance matrix
NASA Astrophysics Data System (ADS)
Kermarrec, Gaël; Schön, Steffen
2016-09-01
Based on the results of Luati and Proietti (Ann Inst Stat Math 63:673-686, 2011) on an equivalence for a certain class of polynomial regressions between the diagonally weighted least squares (DWLS) and the generalized least squares (GLS) estimator, an alternative way to take correlations into account thanks to a diagonal covariance matrix is presented. The equivalent covariance matrix is much easier to compute than a diagonalization of the covariance matrix via eigenvalue decomposition which also implies a change of the least squares equations. This condensed matrix, for use in the least squares adjustment, can be seen as a diagonal or reduced version of the original matrix, its elements being simply the sums of the rows elements of the weighting matrix. The least squares results obtained with the equivalent diagonal matrices and those given by the fully populated covariance matrix are mathematically strictly equivalent for the mean estimator in terms of estimate and its a priori cofactor matrix. It is shown that this equivalence can be empirically extended to further classes of design matrices such as those used in GPS positioning (single point positioning, precise point positioning or relative positioning with double differences). Applying this new model to simulated time series of correlated observations, a significant reduction of the coordinate differences compared with the solutions computed with the commonly used diagonal elevation-dependent model was reached for the GPS relative positioning with double differences, single point positioning as well as precise point positioning cases. The estimate differences between the equivalent and classical model with fully populated covariance matrix were below the mm for all simulated GPS cases and below the sub-mm for the relative positioning with double differences. These results were confirmed by analyzing real data. Consequently, the equivalent diagonal covariance matrices, compared with the often used elevation
Malakar, Jadupati; Nayak, Amit Kumar; Goswami, Soumita
2012-01-01
The aim of this investigation was to develop and optimize bisoprolol fumarate matrix tablets for sustained release application by response surface methodology based on 23 factorial design. The effects of the amounts of calcium alginate, HPMC K4M, and Carbopol 943 in bisoprolol fumarate matrix tablets on the properties of bisoprolol fumarate sustained release matrix tablets like drug release and hardness were analyzed and optimized. The observed responses were coincided well with the predicted values by the experimental design. The optimized bisoprolol fumarate matrix tablets showed prolonged sustained release of bisoprolol fumarate over 6 hours. These matrix tablets followed the first-order model with anomalous (non-Fickian) diffusion mechanism. PMID:23378933
Imide modified epoxy matrix resins
NASA Technical Reports Server (NTRS)
Scola, D. A.
1984-01-01
The results of a program designed to develop tough imide modified epoxy resins cured by bisimide amine (BIA) hardeners are described. State-of-the-art epoxides MY720 and DER383 were used, and four bismide amines were evaluated. These were the BIA's derived from the 6F anhydride (4,4'-(hexafluoroisopropylidene) bis(phthalic anhydride) and the diamines 3,3'-diaminodiphynyl sulfone, 4,4'-oxygianiline, 4,4'-methylene dianiline, and 1,12-dodecane diamine. A key intermediate, designated 6F anhydride, is required for the synthesis of the bisimide amines. Reaction parameters to synthesize a precursor to the 6F anhydride (6FHC) in high yields were investigated. The catalyst trifluoromethane sulfonic acid was studied. Although small scale runs yielded the 6FHC in 50 percent yield, efforts to ranslate these results to a larger scale synthesis gave the 6FHC in only 9 percent yield. Results show that the concept of using bisimide amine as curing agents to improve the toughness properties of epoxies is valid.
Sticky Matrix: Adhesion Mechanism of the Staphylococcal Polysaccharide Intercellular Adhesin.
Formosa-Dague, Cécile; Feuillie, Cécile; Beaussart, Audrey; Derclaye, Sylvie; Kucharíková, Soňa; Lasa, Iñigo; Van Dijck, Patrick; Dufrêne, Yves F
2016-03-22
The development of bacterial biofilms on surfaces leads to hospital-acquired infections that are difficult to fight. In Staphylococci, the cationic polysaccharide intercellular adhesin (PIA) forms an extracellular matrix that connects the cells together during biofilm formation, but the molecular forces involved are unknown. Here, we use advanced force nanoscopy techniques to unravel the mechanism of PIA-mediated adhesion in a clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) strain. Nanoscale multiparametric imaging of the structure, adhesion, and elasticity of bacteria expressing PIA shows that the cells are surrounded by a soft and adhesive matrix of extracellular polymers. Cell surface softness and adhesion are dramatically reduced in mutant cells deficient for the synthesis of PIA or under unfavorable growth conditions. Single-cell force spectroscopy demonstrates that PIA promotes cell-cell adhesion via the multivalent electrostatic interaction with polyanionic teichoic acids on the S. aureus cell surface. This binding mechanism rationalizes, at the nanoscale, the well-known ability of PIA to strengthen intercellular adhesion in staphylococcal biofilms. Force nanoscopy offers promising prospects for understanding the fundamental forces in antibiotic-resistant biofilms and for designing anti-adhesion compounds targeting matrix polymers.
Magnetic properties of iron cluster/chromium matrix nanocomposites
Kruk, Robert; Wang, Di; Hahn, Horst
2015-01-01
Summary A custom-designed apparatus was used for the fine-tuned co-deposition of preformed Fe clusters into antiferromagnetic Cr matrices. Three series of samples with precisely defined cluster sizes, with accuracy to a few atoms, and controlled concentrations were fabricated, followed by a complete characterization of structure and magnetic performance. Relevant magnetic characteristics, reflecting the ferromagnetic/antiferromagnetic coupling between Fe clusters and the Cr matrix, i.e., blocking temperature, coercivity field, and exchange bias were measured and their dependence on cluster size and cluster concentration in the matrix was analyzed. It is evident that the blocking temperatures are clearly affected by both the cluster size and their concentration in the Cr matrix. In contrast the coercivity shows hardly any dependence on size or inter-cluster distance. The exchange bias was found to be strongly sensitive to the cluster size but not to the inter-cluster distances. Therefore, it was concluded to be an effect that is purely localized at the interfaces. PMID:26171292
Boundary formulations for sensitivity analysis without matrix derivatives
NASA Technical Reports Server (NTRS)
Kane, J. H.; Guru Prasad, K.
1993-01-01
A new hybrid approach to continuum structural shape sensitivity analysis employing boundary element analysis (BEA) is presented. The approach uses iterative reanalysis to obviate the need to factor perturbed matrices in the determination of surface displacement and traction sensitivities via a univariate perturbation/finite difference (UPFD) step. The UPFD approach makes it possible to immediately reuse existing subroutines for computation of BEA matrix coefficients in the design sensitivity analysis process. The reanalysis technique computes economical response of univariately perturbed models without factoring perturbed matrices. The approach provides substantial computational economy without the burden of a large-scale reprogramming effort.
TRAC-P validation test matrix. Revision 1.0
Hughes, E.D.; Boyack, B.E.
1997-09-05
This document briefly describes the elements of the Nuclear Regulatory Commission`s (NRC`s) software quality assurance program leading to software (code) qualification and identifies a test matrix for qualifying Transient Reactor Analysis Code (TRAC)-Pressurized Water Reactor Version (-P), or TRAC-P, to the NRC`s software quality assurance requirements. Code qualification is the outcome of several software life-cycle activities, specifically, (1) Requirements Definition, (2) Design, (3) Implementation, and (4) Qualification Testing. The major objective of this document is to define the TRAC-P Qualification Testing effort.
Parallel distance matrix computation for Matlab data mining
NASA Astrophysics Data System (ADS)
Skurowski, Przemysław; Staniszewski, Michał
2016-06-01
The paper presents utility functions for computing of a distance matrix, which plays a crucial role in data mining. The goal in the design was to enable operating on relatively large datasets by overcoming basic shortcoming - computing time - with an interface easy to use. The presented solution is a set of functions, which were created with emphasis on practical applicability in real life. The proposed solution is presented along the theoretical background for the performance scaling. Furthermore, different approaches of the parallel computing are analyzed, including shared memory, which is uncommon in Matlab environment.
Thermal-vacuum effects on polymer matrix composite materials
NASA Technical Reports Server (NTRS)
Tennyson, R. C.; Mabson, G. E.
1991-01-01
Results are presented on the thermal-vacuum response of a variety of fiber reinforced polymers matrix composites that comprised the UTIAS experiment on the LDEF satellite. Theoretical temperature-time predictions for this experiment are in excellent agreement with test data. Results also show quite clearly the effect of outgassing in the dimensional changes of these materials and the corresponding coefficients of thermal expansion. Finally, comparison with ground-based simulation tests are presented as well. Use of these data for design purposes are also given.
Ginsparg, P.
1991-01-01
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
Ginsparg, P.
1991-12-31
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
Amyloid Structures as Biofilm Matrix Scaffolds
Taglialegna, Agustina; Lasa, Iñigo
2016-01-01
Recent insights into bacterial biofilm matrix structures have induced a paradigm shift toward the recognition of amyloid fibers as common building block structures that confer stability to the exopolysaccharide matrix. Here we describe the functional amyloid systems related to biofilm matrix formation in both Gram-negative and Gram-positive bacteria and recent knowledge regarding the interaction of amyloids with other biofilm matrix components such as extracellular DNA (eDNA) and the host immune system. In addition, we summarize the efforts to identify compounds that target amyloid fibers for therapeutic purposes and recent developments that take advantage of the amyloid structure to engineer amyloid fibers of bacterial biofilm matrices for biotechnological applications. PMID:27185827
Superfund Chemical Data Matrix (SCDM) Query
This site allows you to to easily query the Superfund Chemical Data Matrix (SCDM) and generate a list of the corresponding Hazard Ranking System (HRS) factor values, benchmarks, and data elements that you need.
Axial grading of inert matrix fuels
Recktenwald, G. D.; Deinert, M. R.
2012-07-01
Burning actinides in an inert matrix fuel to 750 MWd/kg IHM results in a significant reduction in transuranic isotopes. However, achieving this level of burnup in a standard light water reactor would require residence times that are twice that of uranium dioxide fuels. The reactivity of an inert matrix assembly at the end of life is less than 1/3 of its beginning of life reactivity leading to undesirable radial and axial power peaking in the reactor core. Here we show that axial grading of the inert matrix fuel rods can reduce peaking significantly. Monte Carlo simulations are used to model the assembly level power distributions in both ungraded and graded fuel rods. The results show that an axial grading of uranium dioxide and inert matrix fuels with erbium can reduces power peaking by more than 50% in the axial direction. The reduction in power peaking enables the core to operate at significantly higher power. (authors)
Celsian Glass-Ceramic Matrix Composites
NASA Technical Reports Server (NTRS)
Bansal, Narottam P.; Dicarlo, James A.
1996-01-01
Glass-ceramic matrix reinforced fiber composite materials developed for use in low dielectric applications, such as radomes. Materials strong and tough, exhibit low dielectric properties, and endure high temperatures.
Chondrule-matrix relationships in chondritic meteorites
NASA Technical Reports Server (NTRS)
Brearley, A. J.
1994-01-01
The relationship between chondrules and matrix (fine grained material with a grain size less than 5 micrometers) in chondritic meteorites has been the subject of considerable controversy and no consensus currently exists. The coexistence of these two components in meteorites with bulk compositions that deviate only slightly from CI abundances suggests that cosmochemically their origins are closely linked. Any consideration of the relationship between chondrules and matrix hinges to a large degree on the origin of matrix. The entire spectrum of models exists from matrix as a nebular product to derivation entirely from chondrules. Early models of solar nebular evolution viewed chondrites as a two-component mixture of high- and low-temperature condensates. However, this model has been challenged by the recognition that the nebula was probably not uniformly vaporized.
Matrix Gla protein in tumoral pathology.
Gheorghe, Simona Roxana; Crăciun, Alexandra Mărioara
2016-01-01
Matrix Gla protein is a vitamin K-dependent protein secreted by chondrocytes and vascular smooth muscle cells. The presence of matrix Gla protein was reported in arterial and venous walls, lungs, kidney, uterus, heart, tooth cementum and eyes. Several studies identified matrix Gla protein in tumoral pathology. Until recently, it was thought to only have an inhibitory role of physiological and ectopic calcification. New studies demonstrated that it also has a role in physiological and pathological angiogenesis, as well as in tumorigenesis. The aim of this review is to report the latest findings related to the expression and clinical implications of matrix Gla protein in different types of cancer with an emphasis on cerebral tumors.
Comix, a New Matrix Element Generator
Gleisberg, Tanju; Hoche, Stefan; /Durham U., IPPP
2008-09-03
We present a new tree-level matrix element generator, based on the color dressed Berends-Giele recursive relations. We discuss two new algorithms for phase space integration, dedicated to be used with large multiplicities and color sampling.
Microstructure of Matrix in UHTC Composites
NASA Technical Reports Server (NTRS)
Johnson, Sylvia; Stackpoole, Margaret; Gusman, Michael I.; Chavez-Garia Jose; Doxtad, Evan
2011-01-01
Approaches to controlling the microstructure of Ultra High Temperature Ceramics (UHTCs) are described.. One matrix material has been infiltrated into carbon weaves to make composite materials. The microstructure of these composites is described.
Nuclear waste storage container with metal matrix
Sump, Kenneth R.
1978-01-01
The invention relates to a storage container for high-level waste having a metal matrix for the high-level waste, thereby providing greater impact strength for the waste container and increasing heat transfer properties.
Superfund Chemical Data Matrix (SCDM) Query - Popup
This site allows you to to easily query the Superfund Chemical Data Matrix (SCDM) and generate a list of the corresponding Hazardous Ranking System (HRS) factor values, benchmarks, and data elements that you need.
A graphical R-matrix atomic collision environment
NASA Astrophysics Data System (ADS)
Busby, David William
[/cal R]-matrix theory has been used effectively to compute properties characterising atomic and molecular collisions. Large Fortran packages have been developed over the past twenty-five years, which are esoteric and can sometimes be difficult to use. The aim of this research is to design and implement, using modern computer science techniques, an environment which will render the packages more straight forward and accessible. It is postulated that the interactive manipulation of graphical abstractions of the underlying physics will allow the user to concentrate on the physics of the process being studied. This approach renders the new [/cal R]-matrix packages simple to use by novice and experienced users alike, thereby improving their usefulness to the physics community. The Graphical [/cal R]-matrix Atomic Collision Environment (G[/cal R]ACE) is comprised of four graphical user interfaces. Grace expedites the construction and editing of input data stipulated by the [/cal R]-matrix program packages. Data can be entered symbolically and is extensively validated, through a series of graphical windows. The generated text file enables the [/cal R]-matrix package to be executed on a remote supercomputer to which the workstation is networked. Connected to a database of Clementi-type orbitals, pseudo facilitates the computation of pseudo-orbitals, incorporated in grace. The H-file [/cal B]rowser displays a graphical abstraction representing the physics of an inner region [/cal R]-matrix computation. This pin-points limitations which may need to be modified to improve the computation. [/cal A]nalysis provides a graphical environment on the local workstation where results of the remote computation may be displayed and interpreted. Eigenphase sums can be displayed graphically as a function of energy, where resonance fits can be performed. [/cal A]nalysis enables further points to be calculated if there is insufficient data. Effective collisions strengths can also be
Shrinkage approach for EEG covariance matrix estimation.
Beltrachini, Leandro; von Ellenrieder, Nicolas; Muravchik, Carlos H
2010-01-01
We present a shrinkage estimator for the EEG spatial covariance matrix of the background activity. We show that such an estimator has some advantages over the maximum likelihood and sample covariance estimators when the number of available data to carry out the estimation is low. We find sufficient conditions for the consistency of the shrinkage estimators and results concerning their numerical stability. We compare several shrinkage schemes and show how to improve the estimator by incorporating known structure of the covariance matrix.
Semiclassical matrix elements from periodic orbits
NASA Technical Reports Server (NTRS)
Eckhardt, B.; Fishman, S.; Mueller, K.; Wintgen, D.
1992-01-01
An extension of Gutzwiller's (1967, 1969, 1970, 1971, 1990) semiclassical theory for chaotic systems that allows a determination of matrix elements in terms of classical periodic orbits. Associated zeta functions are derived. The semiclassical predictions are found to be in good agreement with Fourier transforms of quantum spectra of hydrogen in a magnetic field. Expressions for off-diagonal matrix elements are derived that are extensions of the Bohr correspondence relations for integrable systems.
Semisupervised kernel matrix learning by kernel propagation.
Hu, Enliang; Chen, Songcan; Zhang, Daoqiang; Yin, Xuesong
2010-11-01
The goal of semisupervised kernel matrix learning (SS-KML) is to learn a kernel matrix on all the given samples on which just a little supervised information, such as class label or pairwise constraint, is provided. Despite extensive research, the performance of SS-KML still leaves some space for improvement in terms of effectiveness and efficiency. For example, a recent pairwise constraints propagation (PCP) algorithm has formulated SS-KML into a semidefinite programming (SDP) problem, but its computation is very expensive, which undoubtedly restricts PCPs scalability in practice. In this paper, a novel algorithm, called kernel propagation (KP), is proposed to improve the comprehensive performance in SS-KML. The main idea of KP is first to learn a small-sized sub-kernel matrix (named seed-kernel matrix) and then propagate it into a larger-sized full-kernel matrix. Specifically, the implementation of KP consists of three stages: 1) separate the supervised sample (sub)set X(l) from the full sample set X; 2) learn a seed-kernel matrix on X(l) through solving a small-scale SDP problem; and 3) propagate the learnt seed-kernel matrix into a full-kernel matrix on X . Furthermore, following the idea in KP, we naturally develop two conveniently realizable out-of-sample extensions for KML: one is batch-style extension, and the other is online-style extension. The experiments demonstrate that KP is encouraging in both effectiveness and efficiency compared with three state-of-the-art algorithms and its related out-of-sample extensions are promising too.
Mechanisms balancing skeletal matrix synthesis and degradation.
Blair, Harry C; Zaidi, Mone; Schlesinger, Paul H
2002-01-01
Bone is regulated by evolutionarily conserved signals that balance continuous differentiation of bone matrix-producing cells against apoptosis and matrix removal. This is continued from embryogenesis, where the skeleton differentiates as a solid mass and is shaped into separate bones by cell death and proteolysis. The two major tissues of the skeleton are avascular cartilage, with an extracellular matrix based on type II collagen and hydrophilic proteoglycans, and bone, a stronger and lighter material based on oriented type I collagen and hydroxyapatite. Both differentiate from the same mesenchymal stem cells. This differentiation is regulated by a family of related signals centred on bone morphogenic proteins. Fibroblast growth factors, Indian hedgehog and parathyroid hormone-related protein are important in determining the type of matrix and the relation of skeletal and non-skeletal structures. Removal of mineralized matrix involves apoptosis of matrix cells and differentiation of acid-secreting cells (osteoclasts) from macrophage precursors. Key regulators of matrix removal are signals in the tumour-necrosis-factor family. Osteoclasts dissolve bone by isolating a region of the matrix and secreting HCl and proteinases at that site. Successive cycles of removal and replacement allow growth, repair and remodelling. The signals for bone turnover are predominantly cell-membrane-associated, allowing very specific spatial regulation. In addition to its support function, bone is a reservoir of Ca2+, PO3-(4) and OH-. Secondary modulation of mineral secretion and bone degradation are mediated by humoral signals, including parathyroid hormone and vitamin D, as well as the cytokines that also regulate the underlying cell differentiation. PMID:12023876
Micromechanical Modeling of Woven Metal Matrix Composites
NASA Technical Reports Server (NTRS)
Bednarcyk, Brett A.; Pindera, Marek-Jerzy
1997-01-01
This report presents the results of an extensive micromechanical modeling effort for woven metal matrix composites. The model is employed to predict the mechanical response of 8-harness (8H) satin weave carbon/copper (C/Cu) composites. Experimental mechanical results for this novel high thermal conductivity material were recently reported by Bednarcyk et al. along with preliminary model results. The micromechanics model developed herein is based on an embedded approach. A micromechanics model for the local (micro-scale) behavior of the woven composite, the original method of cells (Aboudi), is embedded in a global (macro-scale) micromechanics model (the three-dimensional generalized method of cells (GMC-3D) (Aboudi). This approach allows representation of true repeating unit cells for woven metal matrix composites via GMC-3D, and representation of local effects, such as matrix plasticity, yarn porosity, and imperfect fiber-matrix bonding. In addition, the equations of GMC-3D were reformulated to significantly reduce the number of unknown quantities that characterize the deformation fields at the microlevel in order to make possible the analysis of actual microstructures of woven composites. The resulting micromechanical model (WCGMC) provides an intermediate level of geometric representation, versatility, and computational efficiency with respect to previous analytical and numerical models for woven composites, but surpasses all previous modeling work by allowing the mechanical response of a woven metal matrix composite, with an elastoplastic matrix, to be examined for the first time. WCGMC is employed to examine the effects of composite microstructure, porosity, residual stresses, and imperfect fiber-matrix bonding on the predicted mechanical response of 8H satin C/Cu. The previously reported experimental results are summarized, and the model predictions are compared to monotonic and cyclic tensile and shear test data. By considering appropriate levels of porosity
Application of Fuzzy Logic to Matrix FMECA
NASA Astrophysics Data System (ADS)
Shankar, N. Ravi; Prabhu, B. S.
2001-04-01
A methodology combining the benefits of Fuzzy Logic and Matrix FMEA is presented in this paper. The presented methodology extends the risk prioritization beyond the conventional Risk Priority Number (RPN) method. Fuzzy logic is used to calculate the criticality rank. Also the matrix approach is improved further to develop a pictorial representation retaining all relevant qualitative and quantitative information of several FMEA elements relationships. The methodology presented is demonstrated by application to an illustrative example.
Random Matrix Analysis of Human EEG Data
NASA Astrophysics Data System (ADS)
Šeba, P.
2003-11-01
We use random matrix theory to demonstrate the existence of generic and subject-independent features of the ensemble of correlation matrices extracted from human EEG data. In particular, the spectral density as well as the level spacings was analyzed and shown to be generic and subject independent. We also investigate number variance distributions. In this case we show that when the measured subject is visually stimulated the number variance displays deviations from the random matrix prediction.
Fibre-Matrix Interaction in Soft Tissue
Guo, Zaoyang
2010-05-21
Although the mechanical behaviour of soft tissue has been extensively studied, the interaction between the collagen fibres and the ground matrix has not been well understood and is therefore ignored by most constitutive models of soft tissue. In this paper, the human annulus fibrosus is used as an example and the potential fibre-matrix interaction is identified by careful investigation of the experimental results of biaxial and uniaxial testing of the human annulus fibrosus. First, the uniaxial testing result of the HAF along the axial direction is analysed and it is shown that the mechanical behaviour of the ground matrix can be well simulated by the incompressible neo-Hookean model when the collagen fibres are all under contraction. If the collagen fibres are stretched, the response of the ground matrix can still be described by the incompressible neo-Hookean model, but the effective stiffness of the matrix depends on the fibre stretch ratio. This stiffness can be more than 10 times larger than the one obtained with collagen fibres under contraction. This phenomenon can only be explained by the fibre-matrix interaction. Furthermore, we find that the physical interpretation of this interaction includes the inhomogeneity of the soft tissue and the fibre orientation dispersion. The dependence of the tangent stiffness of the matrix on the first invariant of the deformation tensor can also be explained by the fibre orientation dispersion. The significant effect of the fibre-matrix interaction strain energy on mechanical behaviour of the soft tissue is also illustrated by comparing some simulation results.
Nanophosphor composite scintillator with a liquid matrix
McKigney, Edward Allen; Burrell, Anthony Keiran; Bennett, Bryan L.; Cooke, David Wayne; Ott, Kevin Curtis; Bacrania, Minesh Kantilal; Del Sesto, Rico Emilio; Gilbertson, Robert David; Muenchausen, Ross Edward; McCleskey, Thomas Mark
2010-03-16
An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.
Fuel cell with electrolyte matrix assembly
Kaufman, Arthur; Pudick, Sheldon; Wang, Chiu L.
1988-01-01
This invention is directed to a fuel cell employing a substantially immobilized electrolyte imbedded therein and having a laminated matrix assembly disposed between the electrodes of the cell for holding and distributing the electrolyte. The matrix assembly comprises a non-conducting fibrous material such as silicon carbide whiskers having a relatively large void-fraction and a layer of material having a relatively small void-fraction.
Molten carbonate fuel cell matrix tape
Vine, R.W.; Schroll, C.R.; Reiser, C.A.
1986-04-08
A matrix material for a molten carbonate fuel cell is described comprising particles inert to molten carbonate electrolyte having a particle size less than about 1 micron, ceramic particles having a particle size greater than about 25 microns, and an organic polymeric binder material, the binder material being present in an amount at least about 35% by volume, the matrix material being flexible, pliable, and compliant at room temperature.
Cryogenic regenerator including sarancarbon heat conduction matrix
NASA Technical Reports Server (NTRS)
Jones, Jack A. (Inventor); Petrick, S. Walter (Inventor); Britcliffe, Michael J. (Inventor)
1989-01-01
A saran carbon matrix is employed to conduct heat through the heat storing volume of a cryogenic regenerator. When helium is adsorbed into the saran carbon matrix, the combination exhibits a volumetric specific heat much higher than previously used lead balls. A helium adsorbed saran regenerator should allow much lower refrigerator temperatures than those practically obtainable with lead based regenerators for regenerator type refrigeration systems.
Thorpe, C T; Chaudhry, S; Lei, I I; Varone, A; Riley, G P; Birch, H L; Clegg, P D; Screen, H R C
2015-08-01
Tendon injury is thought to involve both damage accumulation within the matrix and an accompanying cell response. While several studies have characterized cell and matrix response in chronically injured tendons, few have assessed the initial response of tendon to overload-induced damage. In this study, we assessed cell response to cyclic loading. Fascicle bundles from the equine superficial digital flexor tendon were exposed to cyclic loading in vitro, designed to mimic a bout of high-intensity exercise. Changes in cell morphology and protein-level alterations in markers of matrix inflammation and degradation were investigated. Loading resulted in matrix damage, which was accompanied by cells becoming rounder. The inflammatory markers cyclooxygenase-2 and interleukin-6 were increased in loaded samples, as were matrix metalloproteinase-13 and the collagen degradation marker C1,2C. These results indicate upregulation of inflammatory and degradative pathways in response to overload-induced in vitro, which may be initiated by alterations in cell strain environment because of localized matrix damage. This provides important information regarding the initiation of tendinopathy, suggesting that inflammation may play an important role in the initial cell response to tendon damage. Full understanding of the early tenocyte response to matrix damage is critical in order to develop effective treatments for tendinopathy.
Schauer, Kevin L.; LeMoine, Christophe M. R.; Pelin, Adrian; Corradi, Nicolas; Warren, Wesley C.; Grosell, Martin
2016-01-01
Marine teleost fish produce CaCO3 in their intestine as part of their osmoregulatory strategy. This precipitation is critical for rehydration and survival of the largest vertebrate group on earth, yet the molecular mechanisms that regulate this reaction are unknown. Here, we isolate and characterize an organic matrix associated with the intestinal precipitates produced by Gulf toadfish (Opsanus beta). Toadfish precipitates were purified using two different methods, and the associated organic matrix was extracted. Greater than 150 proteins were identified in the isolated matrix by mass spectrometry and subsequent database searching using an O. beta transcriptomic sequence library produced here. Many of the identified proteins were enriched in the matrix compared to the intestinal fluid, and three showed no substantial homology to any previously characterized protein in the NCBI database. To test the functionality of the isolated matrix, a micro-modified in vitro calcification assay was designed, which revealed that low concentrations of isolated matrix substantially promoted CaCO3 production, where high concentrations showed an inhibitory effect. High concentrations of matrix also decreased the incorporation of magnesium into the forming mineral, potentially providing an explanation for the variability in magnesium content observed in precipitates produced by different fish species. PMID:27694946
NASA Astrophysics Data System (ADS)
Schauer, Kevin L.; Lemoine, Christophe M. R.; Pelin, Adrian; Corradi, Nicolas; Warren, Wesley C.; Grosell, Martin
2016-10-01
Marine teleost fish produce CaCO3 in their intestine as part of their osmoregulatory strategy. This precipitation is critical for rehydration and survival of the largest vertebrate group on earth, yet the molecular mechanisms that regulate this reaction are unknown. Here, we isolate and characterize an organic matrix associated with the intestinal precipitates produced by Gulf toadfish (Opsanus beta). Toadfish precipitates were purified using two different methods, and the associated organic matrix was extracted. Greater than 150 proteins were identified in the isolated matrix by mass spectrometry and subsequent database searching using an O. beta transcriptomic sequence library produced here. Many of the identified proteins were enriched in the matrix compared to the intestinal fluid, and three showed no substantial homology to any previously characterized protein in the NCBI database. To test the functionality of the isolated matrix, a micro-modified in vitro calcification assay was designed, which revealed that low concentrations of isolated matrix substantially promoted CaCO3 production, where high concentrations showed an inhibitory effect. High concentrations of matrix also decreased the incorporation of magnesium into the forming mineral, potentially providing an explanation for the variability in magnesium content observed in precipitates produced by different fish species.
Automated MALDI matrix deposition method with inkjet printing for imaging mass spectrometry.
Baluya, Dodge L; Garrett, Timothy J; Yost, Richard A
2007-09-01
Careful matrix deposition on tissue samples for matrix-assisted laser desorption/ionization (MALDI) is critical for producing reproducible analyte ion signals. Traditional methods for matrix deposition are often considered an art rather than a science, with significant sample-to-sample variability. Here we report an automated method for matrix deposition, employing a desktop inkjet printer (<$200) with 5760 x 1440 dpi resolution and a six-channel piezoelectric head that delivers 3 pL/drop. The inkjet printer tray, designed to hold CDs and DVDs, was modified to hold microscope slides. Empty ink cartridges were filled with MALDI matrix solutions, including DHB in methanol/water (70:30) at concentrations up to 40 mg/mL. Various samples (including rat brain tissue sections and standards of small drug molecules) were prepared using three deposition methods (electrospray, airbrush, inkjet). A linear ion trap equipped with an intermediate-pressure MALDI source was used for analyses. Optical microscopic examination showed that matrix crystals were formed evenly across the sample. There was minimal background signal after storing the matrix in the cartridges over a 6-month period. Overall, the mass spectral images gathered from inkjet-printed tissue specimens were of better quality and more reproducible than from specimens prepared by the electrospray and airbrush methods.
Multifunctional and stable bone mimic proteinaceous matrix for bone tissue engineering.
Won, Jong-Eun; Yun, Ye-Rang; Jang, Jun-Hyeog; Yang, Sung-Hee; Kim, Joong-Hyun; Chrzanowski, Wojciech; Wall, Ivan B; Knowles, Jonathan C; Kim, Hae-Won
2015-07-01
Biomaterial surface design with biomimetic proteins holds great promise for successful regeneration of tissues including bone. Here we report a novel proteinaceous hybrid matrix mimicking bone extracellular matrix that has multifunctional capacity to promote stem cell adhesion and osteogenesis with excellent stability. Osteocalcin-fibronectin fusion protein holding collagen binding domain was networked with fibrillar collagen, featuring bone extracellular matrix mimic, to provide multifunctional and structurally-stable biomatrices. The hybrid protein, integrated homogeneously with collagen fibrillar networks, preserved structural stability over a month. Biological efficacy of the hybrid matrix was proven onto tethered surface of biopolymer porous scaffolds. Mesenchymal stem cells quickly anchored to the hybrid matrix, forming focal adhesions, and substantially conformed to cytoskeletal extensions, benefited from the fibronectin adhesive domains. Cells achieved high proliferative capacity to reach confluence rapidly and switched to a mature and osteogenic phenotype more effectively, resulting in greater osteogenic matrix syntheses and mineralization, driven by the engineered osteocalcin. The hybrid biomimetic matrix significantly improved in vivo bone formation in calvarial defects over 6 weeks. Based on the series of stimulated biological responses in vitro and in vivo the novel hybrid proteinaceous composition will be potentially useful as stem cell interfacing matrices for osteogenesis and bone regeneration.
Naturally derived myocardial matrix as an injectable scaffold for cardiac tissue engineering
Singelyn, Jennifer M.; DeQuach, Jessica A.; Seif-Naraghi, Sonya B.; Littlefield, Robert B.; Schup-Magoffin, Pamela J.; Christman, Karen L.
2009-01-01
Myocardial tissue lacks the ability to significantly regenerate itself following a myocardial infarction, thus tissue engineering strategies are required for repair. Several injectable materials have been examined for cardiac tissue engineering; however, none have been designed specifically to mimic the myocardium. The goal of this study was to investigate the in vitro properties and in vivo potential of an injectable myocardial matrix designed to mimic the natural myocardial extracellular environment. Porcine myocardial tissue was decellularized and processed to form a myocardial matrix with the ability to gel in vitro at 37°C and in vivo upon injection into rat myocardium. The resulting myocardial matrix maintained a complex composition, including glycosaminoglycan content, and was able to self-assemble to form a nanofibrous structure. Endothelial cells and smooth muscle cells were shown to migrate towards the myocardial matrix both in vitro and in vivo, with a significant increase in arteriole formation at 11 days post-injection. The matrix was also successfully pushed through a clinically used catheter, demonstrating its potential for minimally invasive therapy. Thus, we have demonstrated the initial feasibility and potential of a naturally derived myocardial matrix as an injectable scaffold for cardiac tissue engineering. PMID:19608268
Pseudomonas biofilm matrix composition and niche biology
Mann, Ethan E.; Wozniak, Daniel J.
2014-01-01
Biofilms are a predominant form of growth for bacteria in the environment and in the clinic. Critical for biofilm development are adherence, proliferation, and dispersion phases. Each of these stages includes reinforcement by, or modulation of, the extracellular matrix. Pseudomonas aeruginosa has been a model organism for the study of biofilm formation. Additionally, other Pseudomonas species utilize biofilm formation during plant colonization and environmental persistence. Pseudomonads produce several biofilm matrix molecules, including polysaccharides, nucleic acids, and proteins. Accessory matrix components shown to aid biofilm formation and adaptability under varying conditions are also produced by pseudomonads. Adaptation facilitated by biofilm formation allows for selection of genetic variants with unique and distinguishable colony morphology. Examples include rugose small-colony variants and wrinkly spreaders (WS), which over produce Psl/Pel or cellulose, respectively, and mucoid bacteria that over produce alginate. The well-documented emergence of these variants suggests that pseudomonads take advantage of matrix-building subpopulations conferring specific benefits for the entire population. This review will focus on various polysaccharides as well as additional Pseudomonas biofilm matrix components. Discussions will center on structure–function relationships, regulation, and the role of individual matrix molecules in niche biology. PMID:22212072
Sparse estimation of a covariance matrix.
Bien, Jacob; Tibshirani, Robert J
2011-12-01
We suggest a method for estimating a covariance matrix on the basis of a sample of vectors drawn from a multivariate normal distribution. In particular, we penalize the likelihood with a lasso penalty on the entries of the covariance matrix. This penalty plays two important roles: it reduces the effective number of parameters, which is important even when the dimension of the vectors is smaller than the sample size since the number of parameters grows quadratically in the number of variables, and it produces an estimate which is sparse. In contrast to sparse inverse covariance estimation, our method's close relative, the sparsity attained here is in the covariance matrix itself rather than in the inverse matrix. Zeros in the covariance matrix correspond to marginal independencies; thus, our method performs model selection while providing a positive definite estimate of the covariance. The proposed penalized maximum likelihood problem is not convex, so we use a majorize-minimize approach in which we iteratively solve convex approximations to the original nonconvex problem. We discuss tuning parameter selection and demonstrate on a flow-cytometry dataset how our method produces an interpretable graphical display of the relationship between variables. We perform simulations that suggest that simple elementwise thresholding of the empirical covariance matrix is competitive with our method for identifying the sparsity structure. Additionally, we show how our method can be used to solve a previously studied special case in which a desired sparsity pattern is prespecified.
NASA Astrophysics Data System (ADS)
Smirnov, Andrey
2016-08-01
A torus action on a symplectic variety allows one to construct solutions to the quantum Yang-Baxter equations ( R-matrices). For a torus action on cotangent bundles over flag varieties the resulting R-matrices are the standard rational solutions of the Yang-Baxter equation, well known in the theory of quantum integrable systems. The torus action on the instanton moduli space leads to more complicated R-matrices, depending additionally on two equivariant parameters t 1 and t 2. In this paper we derive an explicit expression for the R-matrix associated with the instanton moduli space. We study its matrix elements and its Taylor expansion in the powers of the spectral parameter. Certain matrix elements of this R-matrix give a generating function for the characteristic classes of tautological bundles over the Hilbert schemes in terms of the bosonic cut-and-join operators. In particular we rederive from the R-matrix the well known Lehn's formula for the first Chern class. We explicitly compute the first several coefficients for the power series expansion of the R-matrix in the spectral parameter. These coefficients are represented by simple contour integrals of some symmetrized bosonic fields.
Temperature dependent nonlinear metal matrix laminae behavior
NASA Technical Reports Server (NTRS)
Barrett, D. J.; Buesking, K. W.
1986-01-01
An analytical method is described for computing the nonlinear thermal and mechanical response of laminated plates. The material model focuses upon the behavior of metal matrix materials by relating the nonlinear composite response to plasticity effects in the matrix. The foundation of the analysis is the unidirectional material model which is used to compute the instantaneous properties of the lamina based upon the properties of the fibers and matrix. The unidirectional model assumes that the fibers properties are constant with temperature and assumes that the matrix can be modelled as a temperature dependent, bilinear, kinematically hardening material. An incremental approach is used to compute average stresses in the fibers and matrix caused by arbitrary mechanical and thermal loads. The layer model is incorporated in an incremental laminated plate theory to compute the nonlinear response of laminated metal matrix composites of general orientation and stacking sequence. The report includes comparisons of the method with other analytical approaches and compares theoretical calculations with measured experimental material behavior. A section is included which describes the limitations of the material model.
Genetic Relationships Between Chondrules, Rims and Matrix
NASA Technical Reports Server (NTRS)
Huss, G. R.; Alexander, C. M. OD.; Palme, H.; Bland, P. A.; Wasson, J. T.
2004-01-01
The most primitive chondrites are composed of chondrules and chondrule fragments, various types of inclusions, discrete mineral grains, metal, sulfides, and fine-grained materials that occur as interchondrule matrix and as chondrule/inclusion rims. Understanding how these components are related is essential for understanding how chondrites and their constituents formed and were processed in the solar nebula. For example, were the first generations of chondrules formed by melting of matrix or matrix precursors? Did chondrule formation result in appreciable transfer of chondrule material into the matrix? Here, we consider three types of data: 1) compositional data for bulk chondrites and matrix, 2) mineralogical and textural information, and 3) the abundances and characteristics of presolar materials that reside in the matrix and rims. We use these data to evaluate the roles of evaporation and condensation, chondrule formation, mixing of different nebular components, and secondary processing both in the nebula and on the parent bodies. Our goal is to identify the things that are reasonably well established and to point out the areas that need additional work.
Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem.
Katsevich, E; Katsevich, A; Singer, A
2015-01-22
In cryo-electron microscopy (cryo-EM), a microscope generates a top view of a sample of randomly oriented copies of a molecule. The problem of single particle reconstruction (SPR) from cryo-EM is to use the resulting set of noisy two-dimensional projection images taken at unknown directions to reconstruct the three-dimensional (3D) structure of the molecule. In some situations, the molecule under examination exhibits structural variability, which poses a fundamental challenge in SPR. The heterogeneity problem is the task of mapping the space of conformational states of a molecule. It has been previously suggested that the leading eigenvectors of the covariance matrix of the 3D molecules can be used to solve the heterogeneity problem. Estimating the covariance matrix is challenging, since only projections of the molecules are observed, but not the molecules themselves. In this paper, we formulate a general problem of covariance estimation from noisy projections of samples. This problem has intimate connections with matrix completion problems and high-dimensional principal component analysis. We propose an estimator and prove its consistency. When there are finitely many heterogeneity classes, the spectrum of the estimated covariance matrix reveals the number of classes. The estimator can be found as the solution to a certain linear system. In the cryo-EM case, the linear operator to be inverted, which we term the projection covariance transform, is an important object in covariance estimation for tomographic problems involving structural variation. Inverting it involves applying a filter akin to the ramp filter in tomography. We design a basis in which this linear operator is sparse and thus can be tractably inverted despite its large size. We demonstrate via numerical experiments on synthetic datasets the robustness of our algorithm to high levels of noise.
Centrifugal casting of metal matrix composites. Ph.D. Thesis
Berger, R.E.
1994-01-01
Metal matrix composites (MMCs) have excellent properties and low material costs, but high manufacturing costs. The primary difficulty in manufacturing MMCs is in forming a tight matrix/reinforcement bond. This dissertation investigates improving the matrix/reinforcement bond through the use of high centrifugal forces. High centrifugal forces promote fiber infiltration (or particle submergence), remove gas voids, and resist particle pushing by the solidification front. Several aluminum matrix MMC samples are formed at up to 2,660 g`s. The project involves: (1) design and construction of a rotating crucible capable of a 690 C, 2,600 g-force environment; (2) a finite differences heat transfer model using an unique technique (spreadsheet iteration) which has application to engineering teaching and simple modeling problems; (3) a bubble buoyancy/surface adhesion analysis to predict maximum surface voids or bubble cling in cast materials; (4) a fluid surface tension effects analysis evaluating particle submergence into a melt, and melt infiltration into a porous media such as a fiber form; (5) creation of samples and direct visual measurement of void sizes in agreement with bubble buoyancy/surface adhesion theory; (6) performance of tests and direct evidence supporting the developed particle submergence/porous media infiltration theories; and (7) creation of samples and direct measurement of material strength under subjection to bending stress. The final conclusion is that use of high centrifugal forces in MMC manufacturing has potential, however it is only useful for large diameter fibers or particles (on the order of 200 micron) and relatively high g-forces (on the order of 2,500 g`s).
Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem*
Katsevich, E.; Katsevich, A.; Singer, A.
2015-01-01
In cryo-electron microscopy (cryo-EM), a microscope generates a top view of a sample of randomly oriented copies of a molecule. The problem of single particle reconstruction (SPR) from cryo-EM is to use the resulting set of noisy two-dimensional projection images taken at unknown directions to reconstruct the three-dimensional (3D) structure of the molecule. In some situations, the molecule under examination exhibits structural variability, which poses a fundamental challenge in SPR. The heterogeneity problem is the task of mapping the space of conformational states of a molecule. It has been previously suggested that the leading eigenvectors of the covariance matrix of the 3D molecules can be used to solve the heterogeneity problem. Estimating the covariance matrix is challenging, since only projections of the molecules are observed, but not the molecules themselves. In this paper, we formulate a general problem of covariance estimation from noisy projections of samples. This problem has intimate connections with matrix completion problems and high-dimensional principal component analysis. We propose an estimator and prove its consistency. When there are finitely many heterogeneity classes, the spectrum of the estimated covariance matrix reveals the number of classes. The estimator can be found as the solution to a certain linear system. In the cryo-EM case, the linear operator to be inverted, which we term the projection covariance transform, is an important object in covariance estimation for tomographic problems involving structural variation. Inverting it involves applying a filter akin to the ramp filter in tomography. We design a basis in which this linear operator is sparse and thus can be tractably inverted despite its large size. We demonstrate via numerical experiments on synthetic datasets the robustness of our algorithm to high levels of noise. PMID:25699132
Modeling the formation of cell-matrix adhesions on a single 3D matrix fiber.
Escribano, J; Sánchez, M T; García-Aznar, J M
2015-11-07
Cell-matrix adhesions are crucial in different biological processes like tissue morphogenesis, cell motility, and extracellular matrix remodeling. These interactions that link cell cytoskeleton and matrix fibers are built through protein clutches, generally known as adhesion complexes. The adhesion formation process has been deeply studied in two-dimensional (2D) cases; however, the knowledge is limited for three-dimensional (3D) cases. In this work, we simulate different local extracellular matrix properties in order to unravel the fundamental mechanisms that regulate the formation of cell-matrix adhesions in 3D. We aim to study the mechanical interaction of these biological structures through a three dimensional discrete approach, reproducing the transmission pattern force between the cytoskeleton and a single extracellular matrix fiber. This numerical model provides a discrete analysis of the proteins involved including spatial distribution, interaction between them, and study of the different phenomena, such as protein clutches unbinding or protein unfolding.
Stout, David A.; Bar-Kochba, Eyal; Estrada, Jonathan B.; Toyjanova, Jennet; Kesari, Haneesh; Reichner, Jonathan S.; Franck, Christian
2016-01-01
Mechanobiology relates cellular processes to mechanical signals, such as determining the effect of variations in matrix stiffness with cell tractions. Cell traction recorded via traction force microscopy (TFM) commonly takes place on materials such as polyacrylamide- and polyethylene glycol-based gels. Such experiments remain limited in physiological relevance because cells natively migrate within complex tissue microenvironments that are spatially heterogeneous and hierarchical. Yet, TFM requires determination of the matrix constitutive law (stress–strain relationship), which is not always readily available. In addition, the currently achievable displacement resolution limits the accuracy of TFM for relatively small cells. To overcome these limitations, and increase the physiological relevance of in vitro experimental design, we present a new approach and a set of associated biomechanical signatures that are based purely on measurements of the matrix's displacements without requiring any knowledge of its constitutive laws. We show that our mean deformation metrics (MDM) approach can provide significant biophysical information without the need to explicitly determine cell tractions. In the process of demonstrating the use of our MDM approach, we succeeded in expanding the capability of our displacement measurement technique such that it can now measure the 3D deformations around relatively small cells (∼10 micrometers), such as neutrophils. Furthermore, we also report previously unseen deformation patterns generated by motile neutrophils in 3D collagen gels. PMID:26929377
Stout, David A; Bar-Kochba, Eyal; Estrada, Jonathan B; Toyjanova, Jennet; Kesari, Haneesh; Reichner, Jonathan S; Franck, Christian
2016-03-15
Mechanobiology relates cellular processes to mechanical signals, such as determining the effect of variations in matrix stiffness with cell tractions. Cell traction recorded via traction force microscopy (TFM) commonly takes place on materials such as polyacrylamide- and polyethylene glycol-based gels. Such experiments remain limited in physiological relevance because cells natively migrate within complex tissue microenvironments that are spatially heterogeneous and hierarchical. Yet, TFM requires determination of the matrix constitutive law (stress-strain relationship), which is not always readily available. In addition, the currently achievable displacement resolution limits the accuracy of TFM for relatively small cells. To overcome these limitations, and increase the physiological relevance of in vitro experimental design, we present a new approach and a set of associated biomechanical signatures that are based purely on measurements of the matrix's displacements without requiring any knowledge of its constitutive laws. We show that our mean deformation metrics (MDM) approach can provide significant biophysical information without the need to explicitly determine cell tractions. In the process of demonstrating the use of our MDM approach, we succeeded in expanding the capability of our displacement measurement technique such that it can now measure the 3D deformations around relatively small cells (∼10 micrometers), such as neutrophils. Furthermore, we also report previously unseen deformation patterns generated by motile neutrophils in 3D collagen gels.
Acid-base-driven matrix-assisted mass spectrometry for targeted metabolomics.
Shroff, Rohit; Rulísek, Lubomír; Doubsky, Jan; Svatos, Ales
2009-06-23
The ability to charge huge biomolecules without breaking them apart has made matrix-assisted laser desorption/ionization (MALDI) mass spectrometry an indispensable tool for biomolecular analysis. Conventional, empirically selected matrices produce abundant matrix ion clusters in the low-mass region (<500 Da), hampering the application of MALDI-MS to metabolomics. An ionization mode of MAILD, a rational protocol for matrix selection based on Brønsted-Lowry acid-base theory and its application to metabolomics, biological screening/profiling/imaging, and clinical diagnostics is illustrated. Numerous metabolites, covering important metabolic pathways (Krebs' cycle, fatty acid and glucosinolate biosynthesis), were detected in extracts, biofluids, and/or in biological tissues (Arabidopsis thaliana, Drosophila melanogaster, Acyrthosiphon pisum, and human blood). This approach moves matrix selection from "black art" to rational design and sets a paradigm for small-molecule analysis via MALDI-MS.
Optical matrix-matrix multiplication method demonstrated by the use of a multifocus hololens.
Liang, Y Z; Liu, H K
1984-08-01
A method of optical matrix-matrix multiplication is presented. The feasibility of the method is also experimentally demonstrated by the use of a dichromated-gelatin multifocus holographic lens (hololens). With the specific values of matrices chosen, the average percentage error between the theoretical and experimental data of the elements of the output matrix of the multiplication of some specific pairs of 3 x 3 matrices is 0.4%, which corresponds to an 8-bit accuracy.
Optical matrix-matrix multiplication method demonstrated by the use of a multifocus hololens
NASA Technical Reports Server (NTRS)
Liu, H. K.; Liang, Y.-Z.
1984-01-01
A method of optical matrix-matrix multiplication is presented. The feasibility of the method is also experimentally demonstrated by the use of a dichromated-gelatin multifocus holographic lens (hololens). With the specific values of matrices chosen, the average percentage error between the theoretical and experimental data of the elements of the output matrix of the multiplication of some specific pairs of 3 x 3 matrices is 0.4 percent, which corresponds to an 8-bit accuracy.
Blast Design of Reinforced Concrete and Masonry Components Retrofitted with FRP
2010-07-01
polymeric resin matrix . The fibers provide strength and stiffness to the composite, while the resin matrix provides stress transfer between fibers...unclassified 2 The most widely used type of polymer matrix for applications in building structures is epoxy resins. Other types of polymer matrix ...to the polymer matrix . All the fiber types in Table 1 can be used for blast design and the choice of fiber type is often an economic one. Table
Method of producing a hybrid matrix fiber composite
Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.
2006-03-28
Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites comprised of two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.
NASA Astrophysics Data System (ADS)
Longbiao, Li
2015-12-01
The matrix multicracking evolution of cross-ply ceramic-matrix composites (CMCs) has been investigated using energy balance approach. The multicracking of cross-ply CMCs was classified into five modes, i.e., (1) mode 1: transverse multicracking; (2) mode 2: transverse multicracking and matrix multicracking with perfect fiber/matrix interface bonding; (3) mode 3: transverse multicracking and matrix multicracking with fiber/matrix interface debonding; (4) mode 4: matrix multicracking with perfect fiber/matrix interface bonding; and (5) mode 5: matrix multicracking with fiber/matrix interface debonding. The stress distributions of four cracking modes, i.e., mode 1, mode 2, mode 3 and mode 5, are analysed using shear-lag model. The matrix multicracking evolution of mode 1, mode 2, mode 3 and mode 5, has been determined using energy balance approach. The effects of ply thickness and fiber volume fraction on matrix multicracking evolution of cross-ply CMCs have been investigated.
INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 1
NASA Technical Reports Server (NTRS)
2003-01-01
INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 16 (FOAM CORE) / CARBON REINFORCED CYANOESTER (CERAMIC MATRIX COMPOSITE - CMC) HOT STRUCTURE, PANEL 884-1: SAMPLE 1
INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 1
NASA Technical Reports Server (NTRS)
2003-01-01
INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 16 (FOAM CORE) / CARBON REINFORCED CYANOESTER (CERAMIC MATRIX COMPOSITE - CMC) HOT STRUCTURE, PANEL 884-1: SAMPLE 3
Imide modified epoxy matrix resins
NASA Technical Reports Server (NTRS)
Scola, D. A.; Pater, R. H.
1981-01-01
High char yield epoxy using novel bisimide amines (BIA's) as curing agents with a state of the art epoxy resin was developed. Stoichiometric quantities of the epoxy resin and the BIA's were studied to determine the cure cycle required for preparation of resin specimens. The bisimide cured epoxies were designated IME's (imide modified epoxy). The physical, thermal and mechanical properties of these novel resins were determined. The levels of moisture absorption exhibited by the bisimide amine cured expoxies (IME's) were considerably lower than the state of the art epoxies. The strain-to-failure of the control resin system was improved 25% by replacement of DDS with 6F-DDS. Each BIA containing resin exhibited twice the char yield of the control resin MY 720/DDS. Graphite fiber reinforced control (C) and IME resins were fabricated and characterized. Two of the composite systems showed superior properties compared to the other Celion 6000/IME composite systems and state of the art graphite epoxy systems. The two systems exhibited excellent wet shear and flexural strengths and moduli at 300 and 350 F.
Space transportation vehicle design evaluation using saturated designs
NASA Technical Reports Server (NTRS)
Unal, Resit
1993-01-01
An important objective in the preliminary design and evaluation of space transportation vehicles is to find the best values of design variables that optimize the performance characteristic (e.g. dry weight). For a given configuration, the vehicle performance can be determined by the use of complex sizing and performance evaluation computer programs. These complex computer programs utilize iterative algorithms and they are generally too expensive and/or difficult to use directly in multidisciplinary design optimization. An alternative is to use response surface methodology (RSM) and obtain quadratic polynomial approximations to the functional relationships between performance characteristics and design variables. In RSM, these approximation models are then used to determine optimum design parameter values and for rapid sensitivity studies. Constructing a second-order model requires that 'n' design parameters be studied at least at 3 levels (values) so that the coefficients in the model can be estimated. There, 3(n) factorial experiments (point designs or observations) may be necessary. For small values of 'n' such as two or three, this design works well. However, when a large number of design parameters are under study, the number of design points required for a full-factorial design may become excessive. Fortunately, these quadratic polynomial approximations can be obtained by selecting an efficient design matrix using central composite designs (CCD) from design of experiments theory. Each unique point design from the CCD matrix is then conducted using computerized analysis tools (e.g. POST, CONSIZ, etc.). In the next step, least squares regression analysis is used to calculate the quadratic polynomial coefficients from the data. However, in some multidisciplinary applications involving a large number of design variables and several disciplines, the computerized performance synthesis programs may get too time consuming and expensive to run even with the use of
Edgar, Lowell T.; Hoying, James B.; Weiss, Jeffrey A.
2015-01-01
Mechanical interactions during angiogenesis, i.e., traction applied by neovessels to the extracellular matrix and the corresponding deformation, are important regulators of growth and neovascularization. We have previously designed, implemented, and validated a coupled model of angiogenesis in which a discrete microvessel growth model interacts with a continuous finite element mesh through the application of local remodeling sprout stresses (Edgar et al. in Biomech Model Mechanobiol, 2014). However, the initial implementation of this framework does not take matrix density into account when determined these remodeling stresses and is therefore insufficient for the study of angiogenesis within heterogeneous matrix environments such as those found in vivo. The objective of this study was to implement sensitivity to matrix density in the active stress generation within AngioFE in order to allow the study of angiogenic growth within a heterogeneous density environment. We accomplished this by scaling active sprout stresses relative to local matrix density using a scaling factor previously determined from experimental data. We then exercised the new functionality of the model by simulating angiogenesis within four different scenarios: homogeneous density, a narrow gap model, and matrix density gradient, and a construct subjected to repeated loading/unloading and preconditioning. These numerical experiments predicted heterogeneous matrix density in the initially homogeneous case, the closure and alignment of microvessels along a low-density gap, the formation of a unique cap-like structure during angiogenesis within a density gradient, and the alignment of microvessels in the absence of applied load due to preconditioning. The result of these in silico investigations demonstrate how matrix heterogeneity affects neovascularization and matrix deformation and provides a platform for studying angiogenesis in complicated and multi-faceted mechanical environments that
Elongated polyproline motifs facilitate enamel evolution through matrix subunit compaction.
Jin, Tianquan; Ito, Yoshihiro; Luan, Xianghong; Dangaria, Smit; Walker, Cameron; Allen, Michael; Kulkarni, Ashok; Gibson, Carolyn; Braatz, Richard; Liao, Xiubei; Diekwisch, Thomas G H
2009-12-01
Vertebrate body designs rely on hydroxyapatite as the principal mineral component of relatively light-weight, articulated endoskeletons and sophisticated tooth-bearing jaws, facilitating rapid movement and efficient predation. Biological mineralization and skeletal growth are frequently accomplished through proteins containing polyproline repeat elements. Through their well-defined yet mobile and flexible structure polyproline-rich proteins control mineral shape and contribute many other biological functions including Alzheimer's amyloid aggregation and prolamine plant storage. In the present study we have hypothesized that polyproline repeat proteins exert their control over biological events such as mineral growth, plaque aggregation, or viscous adhesion by altering the length of their central repeat domain, resulting in dramatic changes in supramolecular assembly dimensions. In order to test our hypothesis, we have used the vertebrate mineralization protein amelogenin as an exemplar and determined the biological effect of the four-fold increased polyproline tandem repeat length in the amphibian/mammalian transition. To study the effect of polyproline repeat length on matrix assembly, protein structure, and apatite crystal growth, we have measured supramolecular assembly dimensions in various vertebrates using atomic force microscopy, tested the effect of protein assemblies on crystal growth by electron microscopy, generated a transgenic mouse model to examine the effect of an abbreviated polyproline sequence on crystal growth, and determined the structure of polyproline repeat elements using 3D NMR. Our study shows that an increase in PXX/PXQ tandem repeat motif length results (i) in a compaction of protein matrix subunit dimensions, (ii) reduced conformational variability, (iii) an increase in polyproline II helices, and (iv) promotion of apatite crystal length. Together, these findings establish a direct relationship between polyproline tandem repeat fragment
Modeling mechanophore activation within a crosslinked glassy matrix
NASA Astrophysics Data System (ADS)
Silberstein, Meredith N.; Min, Kyoungmin; Cremar, Lee D.; Degen, Cassandra M.; Martinez, Todd J.; Aluru, Narayana R.; White, Scott R.; Sottos, Nancy R.
2013-07-01
Mechanically induced reactivity is a promising means for designing self-reporting materials. Mechanically sensitive chemical groups called mechanophores are covalently linked into polymers in order to trigger specific chemical reactions upon mechanical loading. These mechanophores can be linked either within the backbone or as crosslinks between backbone segments. Mechanophore response is sensitive to both the matrix properties and placement within the matrix, providing two avenues for material design. A model framework is developed to describe reactivity of mechanophores located as crosslinks in a glassy polymer matrix. Simulations are conducted at the molecular and macromolecular scales in order to develop macroscale constitutive relations. The model is developed specifically for the case of spiropyran (SP) in lightly crosslinked polymethylmethacrylate (PMMA). This optically trackable mechanophore (fluorescent when activated) allows the model to be assessed in terms of observed experimental behavior. The force modified potential energy surface (FMPES) framework is used in conjunction with ab initio steered molecular dynamics (MD) simulations of SP to determine the mechanophore kinetics. MD simulations of the crosslinked PMMA structure under shear deformation are used to determine the relationship between macroscale stress and local force on the crosslinks. A continuum model implemented in a finite element framework synthesizes these mechanochemical relations with the mechanical behavior. The continuum model with parameters taken directly from the FMPES and MD analyses under predicts stress-driven activation relative to experimental data. The continuum model, with the physically motivated modification of force fluctuations, provides an accurate prediction for monotonic loading across three decades of strain rate and creep loading, suggesting that the fundamental physics are captured.
Elongated Polyproline Motifs Facilitate Enamel Evolution through Matrix Subunit Compaction
Luan, Xianghong; Dangaria, Smit; Walker, Cameron; Allen, Michael; Kulkarni, Ashok; Gibson, Carolyn; Braatz, Richard; Liao, Xiubei; Diekwisch, Thomas G. H.
2009-01-01
Vertebrate body designs rely on hydroxyapatite as the principal mineral component of relatively light-weight, articulated endoskeletons and sophisticated tooth-bearing jaws, facilitating rapid movement and efficient predation. Biological mineralization and skeletal growth are frequently accomplished through proteins containing polyproline repeat elements. Through their well-defined yet mobile and flexible structure polyproline-rich proteins control mineral shape and contribute many other biological functions including Alzheimer's amyloid aggregation and prolamine plant storage. In the present study we have hypothesized that polyproline repeat proteins exert their control over biological events such as mineral growth, plaque aggregation, or viscous adhesion by altering the length of their central repeat domain, resulting in dramatic changes in supramolecular assembly dimensions. In order to test our hypothesis, we have used the vertebrate mineralization protein amelogenin as an exemplar and determined the biological effect of the four-fold increased polyproline tandem repeat length in the amphibian/mammalian transition. To study the effect of polyproline repeat length on matrix assembly, protein structure, and apatite crystal growth, we have measured supramolecular assembly dimensions in various vertebrates using atomic force microscopy, tested the effect of protein assemblies on crystal growth by electron microscopy, generated a transgenic mouse model to examine the effect of an abbreviated polyproline sequence on crystal growth, and determined the structure of polyproline repeat elements using 3D NMR. Our study shows that an increase in PXX/PXQ tandem repeat motif length results (i) in a compaction of protein matrix subunit dimensions, (ii) reduced conformational variability, (iii) an increase in polyproline II helices, and (iv) promotion of apatite crystal length. Together, these findings establish a direct relationship between polyproline tandem repeat fragment
Imide modified epoxy matrix resins
NASA Technical Reports Server (NTRS)
Scola, D. A.
1982-01-01
Results of a program designed to develop tough imide modified epoxy (IME) resins cured by bisimide amine (BIA) hardeners are presented. State of the art epoxy resin, MY720, was used. Three aromatic bisimide amines and one aromatic aliphatic BIA were evaluated. BIA's derived from 6F anhydride (3,3 prime 4,4 prime-(hexafluoro isopropyl idene) bis (phthalic anhydride) and diamines, 3,3 prime-diam nodiphenyl sulfone (3,3 prime-DDS), 4,4 prime-diamino diphenyl sulfone (4,4 prime-DDS), 1.12-dodecane diamine (1,12-DDA) were used. BIA's were abbreviated 6F-3,3 prime-DDS, 6F-4,4 prime-DDS, 6F-3,3 prime-DDS-4,4 prime DDS, and 6F-3,3 prime-DDS-1,12-DDA corresponding to 6F anhydride and diamines mentioned. Epoxy resin and BIA's (MY720/6F-3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA and a 50:50 mixture of a BIA and parent diamine, MY720/6F-3,3 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA/3,3 prime-DDS were studied to determine effect of structure and composition. Effect of the addition of two commercial epoxies, glyamine 200 and glyamine 100 on the properties of several formulations was evaluated. Bisimide amine cured epoxies were designated IME's (imide modified epoxy). Physical, thermal and mechanical properties of these resins were determined. Moisture absorption in boiling water exhibited by several of the IME's was considerably lower than the state of the art epoxies (from 3.2% for the control and state of the art to 2.0 wt% moisture absorption). Char yields are increased from 20% for control and state of the art epoxies to 40% for IME resins. Relative toughness characteristics of IME resins were measured by 10 deg off axis tensile tests of Celion 6000/IME composites. Results show that IME's containing 6F-3,3 prime-DDS or 6F-3,3 prime-DDS-1,12-DDA improved the "toughness" characteristics of composites by about 35% (tensile strength), about 35% (intralaminar shear
Development of Ceramic Matrix Composite Turbine Blisks for Rocket Engines
NASA Technical Reports Server (NTRS)
Effinger, Mike; Genge, Gary; Kiser, J. Douglas; Munafo, Paul M. (Technical Monitor)
2000-01-01
Ceramic matrix composite (CMC) integrally bladed turbine disks (blisks) are being considered for use in various advanced propulsion systems for space vehicles. The successful development of this technology can significantly impact National Aeronautics and Space Administration (NASA) space transportation missions, by enabling new efficient systems that can operate at higher temperatures, while reducing costs. Composite blisks comprised of carbon (C) fibers and a silicon carbide (SiC) ceramic matrix were designed, fabricated, characterized, and tested by a multidisciplinary team involving materials, design, structural analysis, turbomachinery, and nondestructive evaluation representatives from government, academia, and industry during a 4.5 year effort led by the NASA Marshall Space Flight Center (MSFC). The testing of several of these blisks, which were developed in the Simplex Turbopump CMC Blisk ]Program for use in rocket engine turbopumps, was recently completed. CMC blisks offer potential advantages in rocket engine turbopumps including increased safety resulting from increased operating temperature margins and greater pump reliability, and decreased costs resulting from improved turbopump performance. The progress that was achieved in that development effort is reviewed, and some of the technology that could be applied to other advanced space transportation propulsion systems is discussed.
METCAN-PC - METAL MATRIX COMPOSITE ANALYZER
NASA Technical Reports Server (NTRS)
Murthy, P. L.
1994-01-01
High temperature metal matrix composites offer great potential for use in advanced aerospace structural applications. The realization of this potential however, requires concurrent developments in (1) a technology base for fabricating high temperature metal matrix composite structural components, (2) experimental techniques for measuring their thermal and mechanical characteristics, and (3) computational methods to predict their behavior. METCAN (METal matrix Composite ANalyzer) is a computer program developed to predict this behavior. METCAN can be used to computationally simulate the non-linear behavior of high temperature metal matrix composites (HT-MMC), thus allowing the potential payoff for the specific application to be assessed. It provides a comprehensive analysis of composite thermal and mechanical performance. METCAN treats material nonlinearity at the constituent (fiber, matrix, and interphase) level, where the behavior of each constituent is modeled accounting for time-temperature-stress dependence. The composite properties are synthesized from the constituent instantaneous properties by making use of composite micromechanics and macromechanics. Factors which affect the behavior of the composite properties include the fabrication process variables, the fiber and matrix properties, the bonding between the fiber and matrix and/or the properties of the interphase between the fiber and matrix. The METCAN simulation is performed as point-wise analysis and produces composite properties which are readily incorporated into a finite element code to perform a global structural analysis. After the global structural analysis is performed, METCAN decomposes the composite properties back into the localized response at the various levels of the simulation. At this point the constituent properties are updated and the next iteration in the analysis is initiated. This cyclic procedure is referred to as the integrated approach to metal matrix composite analysis. METCAN
A ceramic matrix composite thermal protection system for hypersonic vehicles
NASA Technical Reports Server (NTRS)
Riccitiello, Salvatore R.; Love, Wendell L.; Pitts, William C.
1993-01-01
The next generation of hypersonic vehicles (NASP, SSTO) that require reusable thermal protection systems will experience acreage surface temperatures in excess of 1100 C. More important, they will experience a more severe physical environment than the Space Shuttle due to non-pristine launching and landing conditions. As a result, maintenance, inspection, and replacement factors must be more thoroughly incorporated into the design of the TPS. To meet these requirements, an advanced thermal protection system was conceived, designated 'TOPHAT'. This system consists of a toughened outer ceramic matrix composite (CMC) attached to a rigid reusable surface insulator (RSI) which is directly bonded to the surface. The objective of this effort was to evaluate this concept in an aeroconvective environment, to determine the effect of impacts to the CMC material, and to compare the results with existing thermal protection systems.
Probabilistic Evaluation of Bolted Joints in Polymer Matrix Composites
NASA Technical Reports Server (NTRS)
Chamis, C. C.; Minnetyan, L.
1997-01-01
Computational methods are described to probabilistically simulate fracture in bolted composite structures. Progressive fracture is simulated via an innovative approach independent of stress intensity factors and fracture toughness. The effect on structure damage of design variable uncertainties is quantified. The Fast Probability Integrator is used to assess the scatter in the composite structure response before and after damage. Sensitivity of the response to design variables is evaluated. The methods are demonstrated for bolted joint polymer matrix composite panels under end loads. The effects of fabrication process are included in the simulation of damage in the bolted panel. The results show that the most effective way to reduce the end displacement at fracture is to control the load and ply thickness.
Tensile Properties of Polymeric Matrix Composites Subjected to Cryogenic Environments
NASA Technical Reports Server (NTRS)
Whitley, Karen S.; Gates, Thomas S.
2004-01-01
Polymer matrix composites (PMC s) have seen limited use as structural materials in cryogenic environments. One reason for the limited use of PMC s in cryogenic structures is a design philosophy that typically requires a large, validated database of material properties in order to ensure a reliable and defect free structure. It is the intent of this paper to provide an initial set of mechanical properties developed from experimental data of an advanced PMC (IM7/PETI-5) exposed to cryogenic temperatures and mechanical loading. The application of this data is to assist in the materials down-select and design of cryogenic fuel tanks for future reusable space vehicles. The details of the material system, test program, and experimental methods will be outlined. Tension modulus and strength were measured at room temperature, -196 C, and -269 C on five different laminates. These properties were also tested after aging at -186 C with and without loading applied. Microcracking was observed in one laminate.
Inelastic deformation of metal matrix composites
NASA Technical Reports Server (NTRS)
Lissenden, C. J.; Herakovich, C. T.; Pindera, M-J.
1993-01-01
A theoretical model capable of predicting the thermomechanical response of continuously reinforced metal matrix composite laminates subjected to multiaxial loading was developed. A micromechanical model is used in conjunction with nonlinear lamination theory to determine inelastic laminae response. Matrix viscoplasticity, residual stresses, and damage to the fiber/matrix interfacial zone are explicitly included in the model. The representative cell of the micromechanical model is considered to be in a state of generalized plane strain, enabling a quasi two-dimensional analysis to be performed. Constant strain finite elements are formulated with elastic-viscoplastic constitutive equations. Interfacial debonding is incorporated into the model through interface elements based on the interfacial debonding theory originally presented by Needleman, and modified by Tvergaard. Nonlinear interfacial constitutive equations relate interfacial tractions to displacement discontinuities at the interface. Theoretical predictions are compared with the results of an experimental program conducted on silicon carbide/titanium (SiC/Ti) unidirectional, (O4), and angle-ply, (+34)(sub s), tubular specimens. Multiaxial loading included increments of axial tension, compression, torque, and internal pressure. Loadings were chosen in an effort to distinguish inelastic deformation due to damage from matrix plasticity and separate time-dependent effects from time-independent effects. Results show that fiber/matrix debonding is nonuniform throughout the composite and is a major factor in the effective response. Also, significant creep behavior occurs at relatively low applied stress levels at room temperature.
Max-min distance nonnegative matrix factorization.
Wang, Jim Jing-Yan; Gao, Xin
2015-01-01
Nonnegative Matrix Factorization (NMF) has been a popular representation method for pattern classification problems. It tries to decompose a nonnegative matrix of data samples as the product of a nonnegative basis matrix and a nonnegative coefficient matrix. The columns of the coefficient matrix can be used as new representations of these data samples. However, traditional NMF methods ignore class labels of the data samples. In this paper, we propose a novel supervised NMF algorithm to improve the discriminative ability of the new representation by using the class labels. Using the class labels, we separate all the data sample pairs into within-class pairs and between-class pairs. To improve the discriminative ability of the new NMF representations, we propose to minimize the maximum distance of the within-class pairs in the new NMF space, and meanwhile to maximize the minimum distance of the between-class pairs. With this criterion, we construct an objective function and optimize it with regard to basis and coefficient matrices, and slack variables alternatively, resulting in an iterative algorithm. The proposed algorithm is evaluated on three pattern classification problems and experiment results show that it outperforms the state-of-the-art supervised NMF methods.
Convex Banding of the Covariance Matrix.
Bien, Jacob; Bunea, Florentina; Xiao, Luo
2016-01-01
We introduce a new sparse estimator of the covariance matrix for high-dimensional models in which the variables have a known ordering. Our estimator, which is the solution to a convex optimization problem, is equivalently expressed as an estimator which tapers the sample covariance matrix by a Toeplitz, sparsely-banded, data-adaptive matrix. As a result of this adaptivity, the convex banding estimator enjoys theoretical optimality properties not attained by previous banding or tapered estimators. In particular, our convex banding estimator is minimax rate adaptive in Frobenius and operator norms, up to log factors, over commonly-studied classes of covariance matrices, and over more general classes. Furthermore, it correctly recovers the bandwidth when the true covariance is exactly banded. Our convex formulation admits a simple and efficient algorithm. Empirical studies demonstrate its practical effectiveness and illustrate that our exactly-banded estimator works well even when the true covariance matrix is only close to a banded matrix, confirming our theoretical results. Our method compares favorably with all existing methods, in terms of accuracy and speed. We illustrate the practical merits of the convex banding estimator by showing that it can be used to improve the performance of discriminant analysis for classifying sound recordings.
Algebraic construction of the Darboux matrix revisited
NASA Astrophysics Data System (ADS)
Cieśliński, Jan L.
2009-10-01
We present algebraic construction of Darboux matrices for 1+1-dimensional integrable systems of nonlinear partial differential equations with a special stress on the nonisospectral case. We discuss different approaches to the Darboux-Bäcklund transformation, based on different λ-dependences of the Darboux matrix: polynomial, sum of partial fractions or the transfer matrix form. We derive symmetric N-soliton formulae in the general case. The matrix spectral parameter and dressing actions in loop groups are also discussed. We describe reductions to twisted loop groups, unitary reductions, the matrix Lax pair for the KdV equation and reductions of chiral models (harmonic maps) to SU(n) and to Grassmann spaces. We show that in the KdV case the nilpotent Darboux matrix generates the binary Darboux transformation. The paper is intended as a review of known results (usually presented in a novel context) but some new results are included as well, e.g., general compact formulae for N-soliton surfaces and linear and bilinear constraints on the nonisospectral Lax pair matrices which are preserved by Darboux transformations.
Phylogenetic Stochastic Mapping Without Matrix Exponentiation
Irvahn, Jan; Minin, Vladimir N.
2014-01-01
Abstract Phylogenetic stochastic mapping is a method for reconstructing the history of trait changes on a phylogenetic tree relating species/organism carrying the trait. State-of-the-art methods assume that the trait evolves according to a continuous-time Markov chain (CTMC) and works well for small state spaces. The computations slow down considerably for larger state spaces (e.g., space of codons), because current methodology relies on exponentiating CTMC infinitesimal rate matrices—an operation whose computational complexity grows as the size of the CTMC state space cubed. In this work, we introduce a new approach, based on a CTMC technique called uniformization, which does not use matrix exponentiation for phylogenetic stochastic mapping. Our method is based on a new Markov chain Monte Carlo (MCMC) algorithm that targets the distribution of trait histories conditional on the trait data observed at the tips of the tree. The computational complexity of our MCMC method grows as the size of the CTMC state space squared. Moreover, in contrast to competing matrix exponentiation methods, if the rate matrix is sparse, we can leverage this sparsity and increase the computational efficiency of our algorithm further. Using simulated data, we illustrate advantages of our MCMC algorithm and investigate how large the state space needs to be for our method to outperform matrix exponentiation approaches. We show that even on the moderately large state space of codons our MCMC method can be significantly faster than currently used matrix exponentiation methods. PMID:24918812
Phase diagram of matrix compressed sensing
NASA Astrophysics Data System (ADS)
Schülke, Christophe; Schniter, Philip; Zdeborová, Lenka
2016-12-01
In the problem of matrix compressed sensing, we aim to recover a low-rank matrix from a few noisy linear measurements. In this contribution, we analyze the asymptotic performance of a Bayes-optimal inference procedure for a model where the matrix to be recovered is a product of random matrices. The results that we obtain using the replica method describe the state evolution of the Parametric Bilinear Generalized Approximate Message Passing (P-BiG-AMP) algorithm, recently introduced in J. T. Parker and P. Schniter [IEEE J. Select. Top. Signal Process. 10, 795 (2016), 10.1109/JSTSP.2016.2539123]. We show the existence of two different types of phase transition and their implications for the solvability of the problem, and we compare the results of our theoretical analysis to the numerical performance reached by P-BiG-AMP. Remarkably, the asymptotic replica equations for matrix compressed sensing are the same as those for a related but formally different problem of matrix factorization.
Transfer matrix representation for periodic planar media
NASA Astrophysics Data System (ADS)
Parrinello, A.; Ghiringhelli, G. L.
2016-06-01
Sound transmission through infinite planar media characterized by in-plane periodicity is faced by exploiting the free wave propagation on the related unit cells. An appropriate through-thickness transfer matrix, relating a proper set of variables describing the acoustic field at the two external surfaces of the medium, is derived by manipulating the dynamic stiffness matrix related to a finite element model of the unit cell. The adoption of finite element models avoids analytical modeling or the simplification on geometry or materials. The obtained matrix is then used in a transfer matrix method context, making it possible to combine the periodic medium with layers of different nature and to treat both hard-wall and semi-infinite fluid termination conditions. A finite sequence of identical sub-layers through the thickness of the medium can be handled within the transfer matrix method, significantly decreasing the computational burden. Transfer matrices obtained by means of the proposed method are compared with analytical or equivalent models, in terms of sound transmission through barriers of different nature.
Nuclear matrix proteins in human colon cancer.
Keesee, S K; Meneghini, M D; Szaro, R P; Wu, Y J
1994-01-01
The nuclear matrix is the nonchromatin scaffolding of the nucleus. This structure confers nuclear shape, organizes chromatin, and appears to contain important regulatory proteins. Tissue specific nuclear matrix proteins have been found in the rat, mouse, and human. In this study we compared high-resolution two-dimensional gel electropherograms of nuclear matrix protein patterns found in human colon tumors with those from normal colon epithelia. Tumors were obtained from 18 patients undergoing partial colectomy for adenocarcinoma of the colon and compared with tissue from 10 normal colons. We have identified at least six proteins which were present in 18 of 18 colon tumors and 0 of 10 normal tissues, as well as four proteins present in 0 of 18 tumors and in 10 of 10 normal tissues. These data, which corroborate similar findings of cancer-specific nuclear matrix proteins in prostate and breast, suggest that nuclear matrix proteins may serve as important markers for at least some types of cancer. Images PMID:8127905
Thermal stress effects in intermetallic matrix composites
NASA Technical Reports Server (NTRS)
Wright, P. K.; Sensmeier, M. D.; Kupperman, D. S.; Wadley, H. N. G.
1993-01-01
Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.
Anyons and matrix product operator algebras
NASA Astrophysics Data System (ADS)
Bultinck, N.; Mariën, M.; Williamson, D. J.; Şahinoğlu, M. B.; Haegeman, J.; Verstraete, F.
2017-03-01
Quantum tensor network states and more particularly projected entangled-pair states provide a natural framework for representing ground states of gapped, topologically ordered systems. The defining feature of these representations is that topological order is a consequence of the symmetry of the underlying tensors in terms of matrix product operators. In this paper, we present a systematic study of those matrix product operators, and show how this relates entanglement properties of projected entangled-pair states to the formalism of fusion tensor categories. From the matrix product operators we construct a C∗-algebra and find that topological sectors can be identified with the central idempotents of this algebra. This allows us to construct projected entangled-pair states containing an arbitrary number of anyons. Properties such as topological spin, the S matrix, fusion and braiding relations can readily be extracted from the idempotents. As the matrix product operator symmetries are acting purely on the virtual level of the tensor network, the ensuing Wilson loops are not fattened when perturbing the system, and this opens up the possibility of simulating topological theories away from renormalization group fixed points. We illustrate the general formalism for the special cases of discrete gauge theories and string-net models.
A matrix safety frame approach to robot safety for space applications. Thesis
NASA Technical Reports Server (NTRS)
Montgomery, T. D.; Lauderbaugh, L. Ken
1988-01-01
The planned use of autonomous robots in space applications has generated many new safety problems. This thesis assesses safety of autonomous robot systems through the structure of a proposed three-dimensional matrix safety frame. By identifying the common points of accidents and fatalities involving terrestrial robots, reviewing terrestrial robot safety standards, and modifying and extending these results to space applications, hazards are identified and their associated risks assessed. Three components of the safeguarding dimension of the matrix safety frame, safeguarding through design and operation for intrinsic safety, and incorporation of add-on safety systems are explained through examples for both terrestrial and space robots. A space robot hazard identification checklist, a qualitative tool for robot systems designers, is developed using the structure imparted by the matrix safety frame. The development of an expert system from the contents of the checklist is discussed.