Function-Oriented Synthesis: How to Design Simplified Analogues of Antibacterial Nucleoside Natural Products?

PubMed

Ichikawa, Satoshi

2016-06-01

It is important to pursue function-oriented synthesis (FOS), a strategy for the design of less structurally complex targets with comparable or superior activity that can be made in a practical manner, because compared to synthetic drugs, many biologically relevant natural products possess large and complex chemical structures that may restrict chemical modifications in a structure-activity relationship study. In this account, we describe recent efforts to simplify complex nucleoside natural products including caprazamycins. Considering the structure-activity relationship study with several truncated analogues, three types of simplified derivatives, namely, oxazolidine, isoxazolidine, and lactam-fused isoxazolidine-containing uridine derivatives, were designed and efficiently synthesized. These simplified derivatives have exhibited promising antibacterial activities. A significant feature of our studies is the rational and drastic simplification of the molecular architecture of caprazamycins. This study provides a novel strategy for the development of a new type of antibacterial agent effective against drug-resistant bacteria. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Applicability Evaluation of Simplified Cognitive Behavioral Therapy.

PubMed

Zhang, Li; Zhu, Zhipei; Fang, Fang; Shen, Yuan; Liu, Na; Li, Chunbo

2018-04-25

We have developed a structured cognitive behavioral therapy manual for anxiety disorder in China, and the present study evaluated the applicability of simplified cognitive behavioral therapy based on our previous research. To evaluate the applicability of simplified cognitive behavioral therapy (SCBT) on generalized anxiety disorder (GAD) by conducting a multi-center controlled clinical trial. A multi-center controlled clinical trial of SCBT was conducted on patients with GAD, including institutions specializing in mental health and psychiatry units in general hospitals. The participants were divided into 3 groups: SCBT group, SCBT with medication group and medication group. The drop-out rates of these three groups, the therapy satisfaction of patients who received SCBT and the evaluation of SCBT from therapists were compared. (1) There was no significant difference among the drop-out rates in the three groups. (2) Only the duration and times of therapy were significantly different between the two groups of patients who received the SCBT, and the therapy satisfaction of the SCBT group was higher than that of the SCBT with medication group. (3) Eighteen therapists who conducted the SCBT indicated that the manual was easy to comprehend and operate, and this therapy could achieve the therapy goals. The applicability of SCBT for patients with GAD is relatively high, and it is hopeful that SCBT can become a psychological treatment which can be applied in medical institutions of various levels.

Estimating inelastic heavy-particle - hydrogen collision data. II. Simplified model for ionic collisions and application to barium-hydrogen ionic collisions

NASA Astrophysics Data System (ADS)

Belyaev, Andrey K.; Yakovleva, Svetlana A.

2017-12-01

Aims: A simplified model is derived for estimating rate coefficients for inelastic processes in low-energy collisions of heavy particles with hydrogen, in particular, the rate coefficients with high and moderate values. Such processes are important for non-local thermodynamic equilibrium modeling of cool stellar atmospheres. Methods: The derived method is based on the asymptotic approach for electronic structure calculations and the Landau-Zener model for nonadiabatic transition probability determination. Results: It is found that the rate coefficients are expressed via statistical probabilities and reduced rate coefficients. It is shown that the reduced rate coefficients for neutralization and ion-pair formation processes depend on single electronic bound energies of an atomic particle, while the reduced rate coefficients for excitation and de-excitation processes depend on two electronic bound energies. The reduced rate coefficients are calculated and tabulated as functions of electronic bound energies. The derived model is applied to barium-hydrogen ionic collisions. For the first time, rate coefficients are evaluated for inelastic processes in Ba+ + H and Ba2+ + H- collisions for all transitions between the states from the ground and up to and including the ionic state. Tables with calculated data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A33

Molecular dynamics of conformational substates for a simplified protein model

NASA Astrophysics Data System (ADS)

Grubmüller, Helmut; Tavan, Paul

1994-09-01

Extended molecular dynamics simulations covering a total of 0.232 μs have been carried out on a simplified protein model. Despite its simplified structure, that model exhibits properties similar to those of more realistic protein models. In particular, the model was found to undergo transitions between conformational substates at a time scale of several hundred picoseconds. The computed trajectories turned out to be sufficiently long as to permit a statistical analysis of that conformational dynamics. To check whether effective descriptions neglecting memory effects can reproduce the observed conformational dynamics, two stochastic models were studied. A one-dimensional Langevin effective potential model derived by elimination of subpicosecond dynamical processes could not describe the observed conformational transition rates. In contrast, a simple Markov model describing the transitions between but neglecting dynamical processes within conformational substates reproduced the observed distribution of first passage times. These findings suggest, that protein dynamics generally does not exhibit memory effects at time scales above a few hundred picoseconds, but confirms the existence of memory effects at a picosecond time scale.

Enzymolysis kinetics and structural characteristics of rice protein with energy-gathered ultrasound and ultrasound assisted alkali pretreatments.

PubMed

Li, Suyun; Yang, Xue; Zhang, Yanyan; Ma, Haile; Qu, Wenjuan; Ye, Xiaofei; Muatasim, Rahma; Oladejo, Ayobami Olayemi

2016-07-01

This research investigated the structural characteristics and enzymolysis kinetics of rice protein which was pretreated by energy-gathered ultrasound and ultrasound assisted alkali. The structural characteristics of rice protein before and after the pretreatment were performed with surface hydrophobicity and Fourier transform infrared (FTIR). There was an increase in the intensity of fluorescence spectrum and changes in functional groups after the pretreatment on rice protein compared with the control (without ultrasound and ultrasound assisted alkali processed), thus significantly enhancing efficiency of the enzymatic hydrolysis. A simplified kinetic equation for the enzymolysis model with the impeded reaction of enzyme was deduced to successfully describe the enzymatic hydrolysis of rice protein by different pretreatments. The initial observed rate constants (Kin,0) as well as ineffective coefficients (kimp) were proposed and obtained based on the experimental observation. The results showed that the parameter of kin,0 increased after ultrasound and ultrasound assisted alkali pretreatments, which proved the effects of the pretreatments on the substrate enhancing the enzymolysis process and had relation to the structure changes of the pretreatments on the substrate. Furthermore, the applicability of the simplified model was demonstrated by the enzymatic hydrolysis process for other materials. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of a measure of informed choice suitable for use in low literacy populations.

PubMed

Dormandy, Elizabeth; Tsui, Elaine Y L; Marteau, Theresa M

2007-06-01

To assess the reliability and validity of a simplified questionnaire-based measure of informed choice in populations with low literacy. The measure comprises (a) knowledge about the test and (b) attitudes towards undergoing the test. Responses to (a) and (b) together with information on test uptake, are used to classify choices as informed or uninformed. A cross-sectional study of 79 pregnant women (46 women with higher, and 33 with lower education levels) completed a simplified questionnaire, a standardised questionnaire and a semi-structured interview about antenatal sickle cell and thalassaemia (SCT) screening. The measures used were: (a) informed choice, based on knowledge about the test, attitudes towards undergoing the test, and uptake of the test and (b) ease of completion measures. The simplified measures of knowledge and attitudes were able to distinguish between women classified according to interview responses as having good or poor knowledge (knowledge scores 6.8 versus 3.2, p<0.001), and positive or negative attitudes towards undergoing the test (attitude scores 20.6 versus 16.2, p=0.023). There was no difference in rates of informed choice derived from the simplified or standardised measures (54% versus 51%, 95% CI difference -11 to 19). Women with lower levels of education found the simplified questionnaire easier to complete than the standardised version (11.0 versus 9.6, p=0.009). Those with higher levels of education found no difference in ease of completion between the two versions of the questionnaire (11.8 versus 11.6, p=0.54). A simplified questionnaire-based measure of informed choice in antenatal SCT screening is as reliable and valid as a more complex standardised version and for those with less education, easier to complete. The simplified questionnaire-based measure of informed choice is suitable for use in populations with low and high levels of education.

Modeling the initial mechanical response and yielding behavior of gelled crude oil

NASA Astrophysics Data System (ADS)

Lei, Chen; Gang, Liu; Xingguo, Lu; Minghai, Xu; Yuannan, Tang

2018-05-01

The initial mechanical response and yielding behavior of gelled crude oil under constant shear rate conditions were investigated. By putting the Maxwell mechanical analog and a special dashpot in parallel, a quasi-Jeffreys model was obtained. The kinetic equation of the structural parameter in the Houska model was simplified reasonably so that a simplified constitutive equation of the special dashpot was expressed. By introducing a damage factor into the constitutive equation of the special dashpot and the Maxwell mechanical analog, we established a constitutive equation of the quasi-Jeffreys model. Rheological tests of gelled crude oil were conducted by imposing constant shear rates and the relationship between the shear stress and shear strain under different shear rates was plotted. It is found that the constitutive equation can fit the experimental data well under a wide range of shear rates. Based on the fitted parameters in the quasi-Jeffreys model, the shear stress changing rules of the Maxwell mechanical analog and the special dashpot were calculated and analyzed. It is found that the critical yield strain and the corresponding shear strain where shear stress of the Maxwell analog is the maximum change slightly under different shear rates. And then a critical damage softening strain which is irrelevant to the shearing conditions was put forward to describe the yielding behavior of gelled crude oil.

A simplified model for dynamics of cell rolling and cell-surface adhesion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cimrák, Ivan, E-mail: ivan.cimrak@fri.uniza.sk

2015-03-10

We propose a three dimensional model for the adhesion and rolling of biological cells on surfaces. We study cells moving in shear flow above a wall to which they can adhere via specific receptor-ligand bonds based on receptors from selectin as well as integrin family. The computational fluid dynamics are governed by the lattice-Boltzmann method. The movement and the deformation of the cells is described by the immersed boundary method. Both methods are fully coupled by implementing a two-way fluid-structure interaction. The adhesion mechanism is modelled by adhesive bonds including stochastic rules for their creation and rupture. We explore amore » simplified model with dissociation rate independent of the length of the bonds. We demonstrate that this model is able to resemble the mesoscopic properties, such as velocity of rolling cells.« less

Cavitation and Wake Structure of Unsteady Tip Vortex Flows

DTIC Science & Technology

1992-12-10

wake structure generated by three-dimensional lifting surfaces. No longer can the wake be modeled as a simple horseshoe vortex structure with the tip...first initiates. -13- Z Strtn vortex "~Bound vortex "’ ; b Wake 2 Figure 1.5 Far-Field Horseshoe Model of a Finite Wing This figure shows a finite wing...Figure 1.11 Simplified Illustration of Wake Structure Behind an Oscillating Wing This schematic shows a simplified model of the trailing vortex

a Study on Strain Rate Effect in Collision Analysis of Rolling STOCK

NASA Astrophysics Data System (ADS)

Kim, Seung Rok; Koo, Jeong Seo

In this paper, the strain rate effect of energy absorption members in rolling stock is studied using the virtual testing model (VTM) for Korean high speed train (KHST). The VTM of KHST was simulated for two different strain rate conditions. The VTM is composed of FE models for structures, and nonlinear spring/damper models for dynamic components. To simplify numerical model for the full rake KHST, the first three units consist of full flexible multi-body dynamic models, and the remainder does 1-D spring/damper/mass models. To evaluate the strain rate effect of KHST, the crash simulation was performed under the accident scenario for a collision with a rigid mass of 15 tons at 110kph. The numerical results show that the overall crash response of the train is not largely affected as much as expected, but individual components have some different deformations according to strain rate. The deformation of the front end structure without strain rate effect is larger than that with it. However, the deformation of the rear end structure without strain rate effect is smaller than that with it. Finally, the intrusion of the driver's cabin is overestimated for no strain rate effect when compared to the case with it.

Simplified failure sequence evaluation of reactor pressure vessel head corroding in-core instrumentation assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

McVicker, J.P.; Conner, J.T.; Hasrouni, P.N.

1995-11-01

In-Core Instrumentation (ICI) assemblies located on a Reactor Pressure Vessel Head have a history of boric acid leakage. The acid tends to corrode the nuts and studs which fasten the flanges of the assembly, thereby compromising the assembly`s structural integrity. This paper provides a simplified practical approach in determining the likelihood of an undetected progressing assembly stud deterioration, which would lead to a catastrophic loss of reactor coolant. The structural behavior of the In-Core Instrumentation flanged assembly is modeled using an elastic composite section assumption, with the studs transmitting tension and the pressure sealing gasket experiencing compression. Using the abovemore » technique, one can calculate the flange relative deflection and the consequential coolant loss flow rate, as well as the stress in any stud. A solved real life example develops the expected failure sequence and discusses the exigency of leak detection for safe shutdown. In the particular case of Calvert Cliffs Nuclear Power Plant (CCNPP) it is concluded that leak detection occurs before catastrophic failure of the ICI flange assembly.« less

A simplified method for assessing particle deposition rate in aircraft cabins

NASA Astrophysics Data System (ADS)

You, Ruoyu; Zhao, Bin

2013-03-01

Particle deposition in aircraft cabins is important for the exposure of passengers to particulate matter, as well as the airborne infectious diseases. In this study, a simplified method is proposed for initial and quick assessment of particle deposition rate in aircraft cabins. The method included: collecting the inclined angle, area, characteristic length, and freestream air velocity for each surface in a cabin; estimating the friction velocity based on the characteristic length and freestream air velocity; modeling the particle deposition velocity using the empirical equation we developed previously; and then calculating the particle deposition rate. The particle deposition rates for the fully-occupied, half-occupied, 1/4-occupied and empty first-class cabin of the MD-82 commercial airliner were estimated. The results show that the occupancy did not significantly influence the particle deposition rate of the cabin. Furthermore, the simplified human model can be used in the assessment with acceptable accuracy. Finally, the comparison results show that the particle deposition rate of aircraft cabins and indoor environments are quite similar.

Fundamental period of Italian reinforced concrete buildings: comparison between numerical, experimental and Italian code simplified values

NASA Astrophysics Data System (ADS)

Ditommaso, Rocco; Carlo Ponzo, Felice; Auletta, Gianluca; Iacovino, Chiara; Nigro, Antonella

2015-04-01

Aim of this study is a comparison among the fundamental period of reinforced concrete buildings evaluated using the simplified approach proposed by the Italian Seismic code (NTC 2008), numerical models and real values retrieved from an experimental campaign performed on several buildings located in Basilicata region (Italy). With the intention of proposing simplified relationships to evaluate the fundamental period of reinforced concrete buildings, scientists and engineers performed several numerical and experimental campaigns, on different structures all around the world, to calibrate different kind of formulas. Most of formulas retrieved from both numerical and experimental analyses provides vibration periods smaller than those suggested by the Italian seismic code. However, it is well known that the fundamental period of a structure play a key role in the correct evaluation of the spectral acceleration for seismic static analyses. Generally, simplified approaches impose the use of safety factors greater than those related to in depth nonlinear analyses with the aim to cover possible unexpected uncertainties. Using the simplified formula proposed by the Italian seismic code the fundamental period is quite higher than fundamental periods experimentally evaluated on real structures, with the consequence that the spectral acceleration adopted in the seismic static analysis may be significantly different than real spectral acceleration. This approach could produces a decreasing in safety factors obtained using linear and nonlinear seismic static analyses. Finally, the authors suggest a possible update of the Italian seismic code formula for the simplified estimation of the fundamental period of vibration of existing RC buildings, taking into account both elastic and inelastic structural behaviour and the interaction between structural and non-structural elements. Acknowledgements This study was partially funded by the Italian Civil Protection Department within the project DPC-RELUIS 2014 - RS4 ''Seismic observatory of structures and health monitoring''. References R. Ditommaso, M. Vona, M. R. Gallipoli and M. Mucciarelli (2013). Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings. Nat. Hazards Earth Syst. Sci., 13, 1903-1912, 2013. www.nat-hazards-earth-syst-sci.net/13/1903/2013. doi:10.5194/nhess-13-1903-2013

A simplified model for glass formation

NASA Technical Reports Server (NTRS)

Uhlmann, D. R.; Onorato, P. I. K.; Scherer, G. W.

1979-01-01

A simplified model of glass formation based on the formal theory of transformation kinetics is presented, which describes the critical cooling rates implied by the occurrence of glassy or partly crystalline bodies. In addition, an approach based on the nose of the time-temperature-transformation (TTT) curve as an extremum in temperature and time has provided a relatively simple relation between the activation energy for viscous flow in the undercooled region and the temperature of the nose of the TTT curve. Using this relation together with the simplified model, it now seems possible to predict cooling rates using only the liquidus temperature, glass transition temperature, and heat of fusion.

Simplified analytical model and balanced design approach for light-weight wood-based structural panel in bending

Treesearch

Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

2016-01-01

This paper presents a simplified analytical model and balanced design approach for modeling lightweight wood-based structural panels in bending. Because many design parameters are required to input for the model of finite element analysis (FEA) during the preliminary design process and optimization, the equivalent method was developed to analyze the mechanical...

Solution of the comoving-frame equation of transfer in spherically symmetric flows. V - Multilevel atoms. [in early star atmospheres

NASA Technical Reports Server (NTRS)

Mihalas, D.; Kunasz, P. B.

1978-01-01

The coupled radiative transfer and statistical equilibrium equations for multilevel ionic structures in the atmospheres of early-type stars are solved. Both lines and continua are treated consistently; the treatment is applicable throughout a transonic wind, and allows for the presence of background continuum sources and sinks in the transfer. An equivalent-two-level-atoms approach provides the solution for the equations. Calculations for simplified He (+)-like model atoms in parameterized isothermal wind models indicate that subordinate line profiles are sensitive to the assumed mass-loss rate, and to the assumed structure of the velocity law in the atmospheres.

Influence of mass transfer resistance on overall nitrate removal rate in upflow sludge bed reactors.

PubMed

Ting, Wen-Huei; Huang, Ju-Sheng

2006-09-01

A kinetic model with intrinsic reaction kinetics and a simplified model with apparent reaction kinetics for denitrification in upflow sludge bed (USB) reactors were proposed. USB-reactor performance data with and without sludge wasting were also obtained for model verification. An independent batch study showed that the apparent kinetic constants k' did not differ from the intrinsic k but the apparent Ks' was significantly larger than the intrinsic Ks suggesting that the intra-granule mass transfer resistance can be modeled by changes in Ks. Calculations of the overall effectiveness factor, Thiele modulus, and Biot number combined with parametric sensitivity analysis showed that the influence of internal mass transfer resistance on the overall nitrate removal rate in USB reactors is more significant than the external mass transfer resistance. The simulated residual nitrate concentrations using the simplified model were in good agreement with the experimental data; the simulated results using the simplified model were also close to those using the kinetic model. Accordingly, the simplified model adequately described the overall nitrate removal rate and can be used for process design.

Modified off-midline closure of pilonidal sinus disease.

PubMed

Saber, Aly

2014-05-01

Numerous surgical procedures have been described for pilonidal sinus disease, but treatment failure and disease recurrence are frequent. Conventional off-midline flap closures have relatively favorable surgical outcomes, but relatively unfavorable cosmetic outcomes. The author reported outcomes of a new simplified off-midline technique for closure of the defect after complete excision of the sinus tracts. Two hundred patients of both sexes were enrolled for modified D-shaped excisions were used to include all sinuses and their ramifications, with a simplified procedure to close the defect. The overall wound infection rate was 12%, (12.2% for males and 11.1% for females). Wound disruption was necessitating laying the whole wound open and management as open technique. The overall wound disruption rate was 6%, (6.1% for males and 5.5% for females) and the overall recurrence rate was 7%. Our simplified off-midline closure without flap appeared to be comparable to conventional off-midline closure with flap, in terms of wound infection, wound dehiscence, and recurrence. Advantages of the simplified procedure include potentially reduced surgery complexity, reduced surgery time, and improved cosmetic outcome.

Approximate method for calculating free vibrations of a large-wind-turbine tower structure

NASA Technical Reports Server (NTRS)

Das, S. C.; Linscott, B. S.

1977-01-01

A set of ordinary differential equations were derived for a simplified structural dynamic lumped-mass model of a typical large-wind-turbine tower structure. Dunkerley's equation was used to arrive at a solution for the fundamental natural frequencies of the tower in bending and torsion. The ERDA-NASA 100-kW wind turbine tower structure was modeled, and the fundamental frequencies were determined by the simplified method described. The approximate fundamental natural frequencies for the tower agree within 18 percent with test data and predictions analyzed.

Organic thin film transistor with a simplified planar structure

NASA Astrophysics Data System (ADS)

Zhang, Lei; Yu, Jungsheng; Zhong, Jian; Jiang, Yadong

2009-05-01

Organic thin film transistor (OTFT) with a simplified planar structure is described. The gate electrode and the source/drain electrodes of OTFT are processed in one planar structure. And these three electrodes are deposited on the glass substrate by DC sputtering technology using Cr/Ni target. Then the electrode layouts of different width length ratio are made by photolithography technology at the same time. Only one step of deposition and one step of photolithography is needed while conventional process takes at least two steps of deposition and two steps of photolithography. Metal is first prepared on the other side of glass substrate and electrode is formed by photolithography. Then source/drain electrode is prepared by deposition and photolithography on the side with the insulation layer. Compared to conventional process of OTFTs, the process in this work is simplified. After three electrodes prepared, the insulation layer is made by spin coating method. The organic material of polyimide is used as the insulation layer. A small molecular material of pentacene is evaporated on the insulation layer using vacuum deposition as the active layer. The process of OTFTs needs only three steps totally. A semi-auto probe stage is used to connect the three electrodes and the probe of the test instrument. A charge carrier mobility of 0.3 cm2 /V s, is obtained from OTFTs on glass substrates with and on/off current ratio of 105. The OTFTs with the planar structure using simplified process can simplify the device process and reduce the fabrication cost.

Research on simplified parametric finite element model of automobile frontal crash

NASA Astrophysics Data System (ADS)

Wu, Linan; Zhang, Xin; Yang, Changhai

2018-05-01

The modeling method and key technologies of the automobile frontal crash simplified parametric finite element model is studied in this paper. By establishing the auto body topological structure, extracting and parameterizing the stiffness properties of substructures, choosing appropriate material models for substructures, the simplified parametric FE model of M6 car is built. The comparison of the results indicates that the simplified parametric FE model can accurately calculate the automobile crash responses and the deformation of the key substructures, and the simulation time is reduced from 6 hours to 2 minutes.

A Continuous Method for Gene Flow

PubMed Central

Palczewski, Michal; Beerli, Peter

2013-01-01

Most modern population genetics inference methods are based on the coalescence framework. Methods that allow estimating parameters of structured populations commonly insert migration events into the genealogies. For these methods the calculation of the coalescence probability density of a genealogy requires a product over all time periods between events. Data sets that contain populations with high rates of gene flow among them require an enormous number of calculations. A new method, transition probability-structured coalescence (TPSC), replaces the discrete migration events with probability statements. Because the speed of calculation is independent of the amount of gene flow, this method allows calculating the coalescence densities efficiently. The current implementation of TPSC uses an approximation simplifying the interaction among lineages. Simulations and coverage comparisons of TPSC vs. MIGRATE show that TPSC allows estimation of high migration rates more precisely, but because of the approximation the estimation of low migration rates is biased. The implementation of TPSC into programs that calculate quantities on phylogenetic tree structures is straightforward, so the TPSC approach will facilitate more general inferences in many computer programs. PMID:23666937

Mechanistic Studies of ε-Caprolactone Polymerization by (salen)AlOR Complexes and a Predictive Model for Cyclic Ester Polymerizations

PubMed Central

2016-01-01

Aluminum alkoxide complexes (2) of salen ligands with a three-carbon linker and para substituents having variable electron-withdrawing capabilities (X = NO2, Br, OMe) were prepared, and the kinetics of their ring-opening polymerization (ROP) of ε-caprolactone (CL) were investigated as a function of temperature, with the aim of drawing comparisons to similar systems with two-carbon linkers investigated previously (1). While 1 and 2 exhibit saturation kinetics and similar dependences of their ROP rates on substituents X (invariant Keq, similar Hammett ρ = +1.4(1) and 1.2(1) for k2, respectively), ROP by 2 was significantly faster than for 1. Theoretical calculations confirm that, while the reactant structures differ, the transition state geometries are quite similar, and by analyzing the energetics of the involved distortions accompanying the structural changes, a significant contribution to the basis for the rate differences was identified. Using this knowledge, a simplified computational method for evaluating ligand structural influences on cyclic ester ROP rates is proposed that may have utility for future catalyst design. PMID:26900488

Silk-regulated hierarchical hollow magnetite/carbon nanocomposite spheroids for lithium-ion battery anodes.

PubMed

Sheng, Weiqin; Zhu, Guobin; Kaplan, David L; Cao, Chuanbao; Zhu, Hesun; Lu, Qiang

2015-03-20

Hierarchical olive-like structured carbon-Fe3O4 nanocomposite particles composed of a hollow interior and a carbon coated surface are prepared by a facile, silk protein-assisted hydrothermal method. Silk nanofibers as templates and carbon precursors first regulate the formation of hollow Fe2O3 microspheres and then they are converted into carbon by a reduction process into Fe3O4. This process significantly simplifies the fabrication and carbon coating processes to form complex hollow structures. When tested as anode materials for lithium-ion batteries, these hollow carbon-coated particles exhibit high capacity (900 mAh g(-1)), excellent cycle stability (180 cycles) and rate performance due to their unique hierarchical hollow structure and carbon coating.

The effects of temperature and diet on age grading and population age structure determination in Drosophila.

PubMed

Aw, Wen C; Ballard, J William O

2013-10-01

The age structure of natural population is of interest in physiological, life history and ecological studies but it is often difficult to determine. One methodological problem is that samples may need to be invasively sampled preventing subsequent taxonomic curation. A second problem is that it can be very expensive to accurately determine the age structure of given population because large sample sizes are often necessary. In this study, we test the effects of temperature (17 °C, 23 °C and 26 °C) and diet (standard cornmeal and low calorie diet) on the accuracy of the non-invasive, inexpensive and high throughput near-infrared spectroscopy (NIRS) technique to determine the age of Drosophila flies. Composite and simplified calibration models were developed for each sex. Independent sets for each temperature and diet treatments with flies not involved in calibration model were then used to validate the accuracy of the calibration models. The composite NIRS calibration model was generated by including flies reared under all temperatures and diets. This approach permits rapid age measurement and age structure determination in large population of flies as less than or equal to 9 days, or more than 9 days old with 85-97% and 64-99% accuracy, respectively. The simplified calibration models were generated by including flies reared at 23 °C on standard diet. Low accuracy rates were observed when simplified calibration models were used to identify (a) Drosophila reared at 17 °C and 26 °C and (b) 23 °C with low calorie diet. These results strongly suggest that appropriate calibration models need to be developed in the laboratory before this technique can be reliably used in field. These calibration models should include the major environmental variables that change across space and time in the particular natural population to be studied. Copyright © 2013 Elsevier Ltd. All rights reserved.

The σ law of evolutionary dynamics in community-structured population.

PubMed

Tang, Changbing; Li, Xiang; Cao, Lang; Zhan, Jingyuan

2012-08-07

Evolutionary game dynamics in finite populations provide a new framework to understand the selection of traits with frequency-dependent fitness. Recently, a simple but fundamental law of evolutionary dynamics, which we call σ law, describes how to determine the selection between two competing strategies: in most evolutionary processes with two strategies, A and B, strategy A is favored over B in weak selection if and only if σR+S>T+σP. This relationship holds for a wide variety of structured populations with mutation rate and weak selection under certain assumptions. In this paper, we propose a model of games based on a community-structured population and revisit this law under the Moran process. By calculating the average payoffs of A and B individuals with the method of effective sojourn time, we find that σ features not only the structured population characteristics, but also the reaction rate between individuals. That is to say, an interaction between two individuals are not uniform, and we can take σ as a reaction rate between any two individuals with the same strategy. We verify this viewpoint by the modified replicator equation with non-uniform interaction rates in a simplified version of the prisoner's dilemma game (PDG). Copyright © 2012 Elsevier Ltd. All rights reserved.

A simplified method for elastic-plastic-creep structural analysis

NASA Technical Reports Server (NTRS)

Kaufman, A.

1984-01-01

A simplified inelastic analysis computer program (ANSYPM) was developed for predicting the stress-strain history at the critical location of a thermomechanically cycled structure from an elastic solution. The program uses an iterative and incremental procedure to estimate the plastic strains from the material stress-strain properties and a plasticity hardening model. Creep effects are calculated on the basis of stress relaxation at constant strain, creep at constant stress or a combination of stress relaxation and creep accumulation. The simplified method was exercised on a number of problems involving uniaxial and multiaxial loading, isothermal and nonisothermal conditions, dwell times at various points in the cycles, different materials and kinematic hardening. Good agreement was found between these analytical results and nonlinear finite element solutions for these problems. The simplified analysis program used less than 1 percent of the CPU time required for a nonlinear finite element analysis.

A simplified method for elastic-plastic-creep structural analysis

NASA Technical Reports Server (NTRS)

Kaufman, A.

1985-01-01

A simplified inelastic analysis computer program (ANSYPM) was developed for predicting the stress-strain history at the critical location of a thermomechanically cycled structure from an elastic solution. The program uses an iterative and incremental procedure to estimate the plastic strains from the material stress-strain properties and a plasticity hardening model. Creep effects are calculated on the basis of stress relaxation at constant strain, creep at constant stress or a combination of stress relaxation and creep accumulation. The simplified method was exercised on a number of problems involving uniaxial and multiaxial loading, isothermal and nonisothermal conditions, dwell times at various points in the cycles, different materials and kinematic hardening. Good agreement was found between these analytical results and nonlinear finite element solutions for these problems. The simplified analysis program used less than 1 percent of the CPU time required for a nonlinear finite element analysis.

Simplified half-life methods for the analysis of kinetic data

NASA Technical Reports Server (NTRS)

Eberhart, J. G.; Levin, E.

1988-01-01

The analysis of reaction rate data has as its goal the determination of the order rate constant which characterize the data. Chemical reactions with one reactant and present simplified methods for accomplishing this goal are considered. The approaches presented involve the use of half lives or other fractional lives. These methods are particularly useful for the more elementary discussions of kinetics found in general and physical chemistry courses.

Spiral Antenna-Coupled Microbridge Structures for THz Application.

PubMed

Gou, Jun; Zhang, Tian; Wang, Jun; Jiang, Yadong

2017-12-01

Bolometer sensor is a good candidate for THz imaging due to its compact system, low cost, and wideband operation. Based on infrared microbolometer structures, two kinds of antenna-coupled microbridge structures are proposed with different spiral antennas: spiral antenna on support layer and spiral antenna with extended legs. Aiming at applications in detection and imaging, simulations are carried out mainly for optimized absorption at 2.52 THz, which is the radiation frequency of far-infrared CO 2 lasers. The effects of rotation angle, line width, and spacing of the spiral antenna on THz wave absorption of microbridge structures are discussed. Spiral antenna, with extended legs, is a good solution for high absorption rate at low absorption frequency and can be used as electrode lead simultaneously for simplified manufacturing process. A spiral antenna-coupled microbridge structure with an absorption rate of more than 75% at 2.52 THz is achieved by optimizing the structure parameters. This research demonstrates the use of different spiral antennas for enhanced and tunable THz absorption of microbridge structures and provides an effective way to fabricate THz microbolometer detectors with great potential in the application of real-time THz imaging.

Thermal Protection System Cavity Heating for Simplified and Actual Geometries Using Computational Fluid Dynamics Simulations with Unstructured Grids

NASA Technical Reports Server (NTRS)

McCloud, Peter L.

2010-01-01

Thermal Protection System (TPS) Cavity Heating is predicted using Computational Fluid Dynamics (CFD) on unstructured grids for both simplified cavities and actual cavity geometries. Validation was performed using comparisons to wind tunnel experimental results and CFD predictions using structured grids. Full-scale predictions were made for simplified and actual geometry configurations on the Space Shuttle Orbiter in a mission support timeframe.

Simplified and refined finite element approaches for determining stresses and internal forces in geometrically nonlinear structural analysis

NASA Technical Reports Server (NTRS)

Robinson, J. C.

1979-01-01

Two methods for determining stresses and internal forces in geometrically nonlinear structural analysis are presented. The simplified approach uses the mid-deformed structural position to evaluate strains when rigid body rotation is present. The important feature of this approach is that it can easily be used with a general-purpose finite-element computer program. The refined approach uses element intrinsic or corotational coordinates and a geometric transformation to determine element strains from joint displacements. Results are presented which demonstrate the capabilities of these potentially useful approaches for geometrically nonlinear structural analysis.

Simplification of reversible Markov chains by removal of states with low equilibrium occupancy.

PubMed

Ullah, Ghanim; Bruno, William J; Pearson, John E

2012-10-21

We present a practical method for simplifying Markov chains on a potentially large state space when detailed balance holds. A simple and transparent technique is introduced to remove states with low equilibrium occupancy. The resulting system has fewer parameters. The resulting effective rates between the remaining nodes give dynamics identical to the original system's except on very fast timescales. This procedure amounts to using separation of timescales to neglect small capacitance nodes in a network of resistors and capacitors. We illustrate the technique by simplifying various reaction networks, including transforming an acyclic four-node network to a three-node cyclic network. For a reaction step in which a ligand binds, the law of mass action implies a forward rate proportional to ligand concentration. The effective rates in the simplified network are found to be rational functions of ligand concentration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Constraint Logic Programming approach to protein structure prediction.

PubMed

Dal Palù, Alessandro; Dovier, Agostino; Fogolari, Federico

2004-11-30

The protein structure prediction problem is one of the most challenging problems in biological sciences. Many approaches have been proposed using database information and/or simplified protein models. The protein structure prediction problem can be cast in the form of an optimization problem. Notwithstanding its importance, the problem has very seldom been tackled by Constraint Logic Programming, a declarative programming paradigm suitable for solving combinatorial optimization problems. Constraint Logic Programming techniques have been applied to the protein structure prediction problem on the face-centered cube lattice model. Molecular dynamics techniques, endowed with the notion of constraint, have been also exploited. Even using a very simplified model, Constraint Logic Programming on the face-centered cube lattice model allowed us to obtain acceptable results for a few small proteins. As a test implementation their (known) secondary structure and the presence of disulfide bridges are used as constraints. Simplified structures obtained in this way have been converted to all atom models with plausible structure. Results have been compared with a similar approach using a well-established technique as molecular dynamics. The results obtained on small proteins show that Constraint Logic Programming techniques can be employed for studying protein simplified models, which can be converted into realistic all atom models. The advantage of Constraint Logic Programming over other, much more explored, methodologies, resides in the rapid software prototyping, in the easy way of encoding heuristics, and in exploiting all the advances made in this research area, e.g. in constraint propagation and its use for pruning the huge search space.

Modified Off-Midline Closure of Pilonidal Sinus Disease

PubMed Central

Saber, Aly

2014-01-01

Background: Numerous surgical procedures have been described for pilonidal sinus disease, but treatment failure and disease recurrence are frequent. Conventional off-midline flap closures have relatively favorable surgical outcomes, but relatively unfavorable cosmetic outcomes. Aim: The author reported outcomes of a new simplified off-midline technique for closure of the defect after complete excision of the sinus tracts. Patients and Methods: Two hundred patients of both sexes were enrolled for modified D-shaped excisions were used to include all sinuses and their ramifications, with a simplified procedure to close the defect. Results: The overall wound infection rate was 12%, (12.2% for males and 11.1% for females). Wound disruption was necessitating laying the whole wound open and management as open technique. The overall wound disruption rate was 6%, (6.1% for males and 5.5% for females) and the overall recurrence rate was 7%. Conclusion: Our simplified off-midline closure without flap appeared to be comparable to conventional off-midline closure with flap, in terms of wound infection, wound dehiscence, and recurrence. Advantages of the simplified procedure include potentially reduced surgery complexity, reduced surgery time, and improved cosmetic outcome. PMID:24926445

Computational Modeling of Liquid and Gaseous Control Valves

NASA Technical Reports Server (NTRS)

Daines, Russell; Ahuja, Vineet; Hosangadi, Ashvin; Shipman, Jeremy; Moore, Arden; Sulyma, Peter

2005-01-01

In this paper computational modeling efforts undertaken at NASA Stennis Space Center in support of rocket engine component testing are discussed. Such analyses include structurally complex cryogenic liquid valves and gas valves operating at high pressures and flow rates. Basic modeling and initial successes are documented, and other issues that make valve modeling at SSC somewhat unique are also addressed. These include transient behavior, valve stall, and the determination of flow patterns in LOX valves. Hexahedral structured grids are used for valves that can be simplifies through the use of axisymmetric approximation. Hybrid unstructured methodology is used for structurally complex valves that have disparate length scales and complex flow paths that include strong swirl, local recirculation zones/secondary flow effects. Hexahedral (structured), unstructured, and hybrid meshes are compared for accuracy and computational efficiency. Accuracy is determined using verification and validation techniques.

Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.

2010-01-01

This paper details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. The specific test method selected for the standardized test procedure utilizes a single cantilever beam (SCB) specimen configuration. The objective of the current work is to develop a method for establishing SCB specimen dimensions. This is achieved by imposing specific limitations on specimen dimensions, with the objectives of promoting a linear elastic specimen response, and simplifying the data reduction method required for computing the critical strain energy release rate associated with debonding. The sizing method is also designed to be suitable for incorporation into a standardized test protocol. Preliminary application of the resulting sizing method yields practical specimen dimensions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moulin, D.; Chapuliot, S.; Drubay, B.

For structures like vessels or pipes containing a fluid, the Leak-Before-Break (LBB) assessment requires to demonstrate that it is possible, during the lifetime of the component, to detect a rate of leakage due to a possible defect, the growth of which would result in a leak before-break of the component. This LBB assessment could be an important contribution to the overall structural integrity argument for many components. The aim of this paper is to review some practices used for LBB assessment and to describe how some new R & D results have been used to provide a simplified approach ofmore » fracture mechanics analysis and especially the evaluation of crack shape and size during the lifetime of the component.« less

A hybrid phenomenological model for ferroelectroelastic ceramics. Part II: Morphotropic PZT ceramics

NASA Astrophysics Data System (ADS)

Stark, S.; Neumeister, P.; Balke, H.

2016-10-01

In this part II of a two part series, the rate-independent hybrid phenomenological constitutive model introduced in part I is modified to account for the material behavior of morphotropic lead zirconate titanate ceramics (PZT ceramics). The modifications are based on a discussion of the available literature results regarding the micro-structure of these materials. In particular, a monoclinic phase and a highly simplified representation of the hierarchical structure of micro-domains and nano-domains observed experimentally are incorporated into the model. It is shown that experimental data for the commercially available morphotropic PZT material PIC151 (PI Ceramic GmbH, Lederhose, Germany) can be reproduced and predicted based on the modified hybrid model.

Definition of ground test for verification of large space structure control

NASA Technical Reports Server (NTRS)

Doane, G. B., III; Glaese, J. R.; Tollison, D. K.; Howsman, T. G.; Curtis, S. (Editor); Banks, B.

1984-01-01

Control theory and design, dynamic system modelling, and simulation of test scenarios are the main ideas discussed. The overall effort is the achievement at Marshall Space Flight Center of a successful ground test experiment of a large space structure. A simplified planar model of ground test experiment of a large space structure. A simplified planar model of ground test verification was developed. The elimination from that model of the uncontrollable rigid body modes was also examined. Also studied was the hardware/software of computation speed.

Simplifying the complexity of resistance heterogeneity in metastasis

PubMed Central

Lavi, Orit; Greene, James M.; Levy, Doron; Gottesman, Michael M.

2014-01-01

The main goal of treatment regimens for metastasis is to control growth rates, not eradicate all cancer cells. Mathematical models offer methodologies that incorporate high-throughput data with dynamic effects on net growth. The ideal approach would simplify, but not over-simplify, a complex problem into meaningful and manageable estimators that predict a patient’s response to specific treatments. Here, we explore three fundamental approaches with different assumptions concerning resistance mechanisms, in which the cells are categorized into either discrete compartments or described by a continuous range of resistance levels. We argue in favor of modeling resistance as a continuum and demonstrate how integrating cellular growth rates, density-dependent versus exponential growth, and intratumoral heterogeneity improves predictions concerning the resistance heterogeneity of metastases. PMID:24491979

Clinical assessment of early language development: a simplified short form of the Mandarin communicative development inventory.

PubMed

Soli, Sigfrid D; Zheng, Yun; Meng, Zhaoli; Li, Gang

2012-09-01

The purpose of this study was to develop a practical mean for clinical evaluation of early pediatric language development by establishing developmental trajectories for receptive and expressive vocabulary growth in children between 6 and 32 months of age using a simple, time-efficient assessment tool. Simplified short form versions of the Words and Gestures and Words and Sentences vocabulary inventories in the Mandarin Communicative Development Inventory [1] were developed and used to assess early language development in developmentally normal children from 6 to 32 months of age during routine health checks. Developmental trajectories characterizing the rate of receptive and expressive vocabulary growth between 6 and 32 months of age are reported. These trajectories allow the equivalent age corresponding to a score to be determined after a brief structured interview with the child's parents that can be conducted in a busy clinical setting. The simplified short forms of the Mandarin Communicative Development Inventories can serve as a clinically useful tool to assess early child language development, providing a practical mean of objectively assessing early language development following early interventions to treat young children with hearing impairment as well as speech and language delays. Objective evidence of language development is essential for achievement of effective (re)habilitation outcomes. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

48 CFR 41.401 - Monthly and annual review.

Code of Federal Regulations, 2010 CFR

2010-10-01

... values exceeding the simplified acquisition threshold, on an annual basis. Annual reviews of accounts with annual values at or below the simplified acquisition threshold shall be conducted when deemed... services to each facility under the utility's most economical, applicable rate and to examine competitive...

Comparative study on structural and optical properties of CdS films fabricated by three different low-cost techniques

NASA Astrophysics Data System (ADS)

Ravichandran, K.; Philominathan, P.

2009-03-01

Highly crystalline and transparent cadmium sulphide films were fabricated at relatively low temperature by employing an inexpensive, simplified spray technique using perfume atomizer (generally used for cosmetics). The structural, surface morphological and optical properties of the films were studied and compared with that prepared by conventional spray pyrolysis using air as carrier gas and chemical bath deposition. The films deposited by the simplified spray have preferred orientation along (1 0 1) plane. The lattice parameters were calculated as a = 4.138 Å and c = 6.718 Å which are well agreed with that obtained from the other two techniques and also with the standard data. The optical transmittance in the visible range and the optical band gap were found as 85% and 2.43 eV, respectively. The structural and optical properties of the films fabricated by the simplified spray are found to be desirable for opto-electronic applications.

Standard Versus Simplified Consent Materials for Biobank Participation: Differences in Patient Knowledge and Trial Accrual.

PubMed

Garrett, Sarah B; Murphy, Marie; Wiley, James; Dohan, Daniel

2017-12-01

Replacing standard consent materials with simplified materials is a promising intervention to improve patient comprehension, but there is little evidence on its real-world implementation. We employed a sequential two-arm design to compare the effect of standard versus simplified consent materials on potential donors' understanding of biobank processes and their accrual to an active biobanking program. Participants were female patients of a California breast health clinic. Subjects from the simplified arm answered more items correctly ( p = .064), reported "don't know" for fewer items ( p = .077), and consented to donate to the biobank at higher rates ( p = .025) than those from the standard arm. Replacing an extant consent form with a simplified version is feasible and may benefit patient comprehension and study accrual.

Multidisciplinary Optimization Methods for Aircraft Preliminary Design

NASA Technical Reports Server (NTRS)

Kroo, Ilan; Altus, Steve; Braun, Robert; Gage, Peter; Sobieski, Ian

1994-01-01

This paper describes a research program aimed at improved methods for multidisciplinary design and optimization of large-scale aeronautical systems. The research involves new approaches to system decomposition, interdisciplinary communication, and methods of exploiting coarse-grained parallelism for analysis and optimization. A new architecture, that involves a tight coupling between optimization and analysis, is intended to improve efficiency while simplifying the structure of multidisciplinary, computation-intensive design problems involving many analysis disciplines and perhaps hundreds of design variables. Work in two areas is described here: system decomposition using compatibility constraints to simplify the analysis structure and take advantage of coarse-grained parallelism; and collaborative optimization, a decomposition of the optimization process to permit parallel design and to simplify interdisciplinary communication requirements.

Medical Decision-Making Among Elderly People in Long Term Care.

ERIC Educational Resources Information Center

Tymchuk, Alexander J.; And Others

1988-01-01

Presented informed consent information on high and low risk medical procedures to elderly persons in long term care facility in standard, simplified, or storybook format. Comprehension was significantly better for simplified and storybook formats. Ratings of decision-making ability approximated comprehension test results. Comprehension test…

Origami-based mechanical metamaterials with tunable frequency band structures (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yasuda, Hiromi; Pratt, Riley; Yang, Jinkyu

2017-04-01

We investigate wave dynamics in origami-based mechanical metamaterials composed of bellows-like origami structures, specifically the Tachi-Miura Polyhedron (TMP). One of the unique features of the TMP is that its structural deformations take place only along the crease lines, therefore the structure can be made of rigid plates and hinges. By utilizing this feature, we introduce linear torsional springs to model the crease lines and derive the force and displacement relationship of the TMP structure along the longitudinal direction. Our analysis shows strain softening/hardening behaviors in compression/tensile regions respectively, and the force-displacement curve can be manipulated by altering the initial configuration of the TMP (e.g., the initial folding angle). We also fabricate physical prototypes and measure the force-displacement behavior to verify our analytical model. Based on this static analysis on the TMP, we simplify the TMP structure into a linkage model, preserving the tunable strain softening/hardening behaviors. Dynamic analysis is also conducted numerically to analyze the frequency response of the simplified TMP unit cell under harmonic excitations. The simplified TMP exhibits a transition between linear and nonlinear behaviors, which depends on the amplitude of the excitation and the initial configuration. In addition, we design a 1D system composed of simplified TMP unit cells and analyze the relationship between frequency and wave number. If two different configurations of the unit cell (e.g., different initial folding angles) are connected in an alternating arrangement, the system develops frequency bandgaps. These unique static/dynamic behaviors can be exploited to design engineering devices which can handle vibrations and impact in an efficient manner.

Structural considerations for solar installers : an approach for small, simplified solar installations or retrofits.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richards, Elizabeth H.; Schindel, Kay; Bosiljevac, Tom

2011-12-01

Structural Considerations for Solar Installers provides a comprehensive outline of structural considerations associated with simplified solar installations and recommends a set of best practices installers can follow when assessing such considerations. Information in the manual comes from engineering and solar experts as well as case studies. The objectives of the manual are to ensure safety and structural durability for rooftop solar installations and to potentially accelerate the permitting process by identifying and remedying structural issues prior to installation. The purpose of this document is to provide tools and guidelines for installers to help ensure that residential photovoltaic (PV) power systemsmore » are properly specified and installed with respect to the continuing structural integrity of the building.« less

What drives interaction strengths in complex food webs? A test with feeding rates of a generalist stream predator.

PubMed

Preston, Daniel L; Henderson, Jeremy S; Falke, Landon P; Segui, Leah M; Layden, Tamara J; Novak, Mark

2018-05-08

Describing the mechanisms that drive variation in species interaction strengths is central to understanding, predicting, and managing community dynamics. Multiple factors have been linked to trophic interaction strength variation, including species densities, species traits, and abiotic factors. Yet most empirical tests of the relative roles of multiple mechanisms that drive variation have been limited to simplified experiments that may diverge from the dynamics of natural food webs. Here, we used a field-based observational approach to quantify the roles of prey density, predator density, predator-prey body-mass ratios, prey identity, and abiotic factors in driving variation in feeding rates of reticulate sculpin (Cottus perplexus). We combined data on over 6,000 predator-prey observations with prey identification time functions to estimate 289 prey-specific feeding rates at nine stream sites in Oregon. Feeding rates on 57 prey types showed an approximately log-normal distribution, with few strong and many weak interactions. Model selection indicated that prey density, followed by prey identity, were the two most important predictors of prey-specific sculpin feeding rates. Feeding rates showed a positive relationship with prey taxon densities that was inconsistent with predator saturation predicted by current functional response models. Feeding rates also exhibited four orders-of-magnitude in variation across prey taxonomic orders, with the lowest feeding rates observed on prey with significant anti-predator defenses. Body-mass ratios were the third most important predictor variable, showing a hump-shaped relationship with the highest feeding rates at intermediate ratios. Sculpin density was negatively correlated with feeding rates, consistent with the presence of intraspecific predator interference. Our results highlight how multiple co-occurring drivers shape trophic interactions in nature and underscore ways in which simplified experiments or reliance on scaling laws alone may lead to biased inferences about the structure and dynamics of species-rich food webs. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Patients' ratings of genetic conditions validate a taxonomy to simplify decisions about preconception carrier screening via genome sequencing.

PubMed

Leo, Michael C; McMullen, Carmit; Wilfond, Benjamin S; Lynch, Frances L; Reiss, Jacob A; Gilmore, Marian J; Himes, Patricia; Kauffman, Tia L; Davis, James V; Jarvik, Gail P; Berg, Jonathan S; Harding, Cary; Kennedy, Kathleen A; Simpson, Dana Kostiner; Quigley, Denise I; Richards, C Sue; Rope, Alan F; Goddard, Katrina A B

2016-03-01

Advances in genome sequencing and gene discovery have created opportunities to efficiently assess more genetic conditions than ever before. Given the large number of conditions that can be screened, the implementation of expanded carrier screening using genome sequencing will require practical methods of simplifying decisions about the conditions for which patients want to be screened. One method to simplify decision making is to generate a taxonomy based on expert judgment. However, expert perceptions of condition attributes used to classify these conditions may differ from those used by patients. To understand whether expert and patient perceptions differ, we asked women who had received preconception genetic carrier screening in the last 3 years to fill out a survey to rate the attributes (predictability, controllability, visibility, and severity) of several autosomal recessive or X-linked genetic conditions. These conditions were classified into one of five taxonomy categories developed by subject experts (significantly shortened lifespan, serious medical problems, mild medical problems, unpredictable medical outcomes, and adult-onset conditions). A total of 193 women provided 739 usable ratings across 20 conditions. The mean ratings and correlations demonstrated that participants made distinctions across both attributes and categories. Aggregated mean attribute ratings across categories demonstrated logical consistency between the key features of each attribute and category, although participants perceived little difference between the mild and serious categories. This study provides empirical evidence for the validity of our proposed taxonomy, which will simplify patient decisions for results they would like to receive from preconception carrier screening via genome sequencing. © 2016 Wiley Periodicals, Inc.

Effect of livestock grazing in the partitions of a semiarid plant-plant spatial signed network

NASA Astrophysics Data System (ADS)

Saiz, Hugo; Alados, Concepción L.

2014-08-01

In recent times, network theory has become a useful tool to study the structure of the interactions in ecological communities. However, typically, these approaches focus on a particular kind of interaction while neglecting other possible interactions present in the ecosystem. Here, we present an ecological network for plant communities that consider simultaneously positive and negative interactions, which were derived from the spatial association and segregation between plant species. We employed this network to study the structure and the association strategies in a semiarid plant community of Cabo de Gata-Níjar Natural Park, SE Spain, and how they changed in 4 sites that differed in stocking rate. Association strategies were obtained from the partitions of the network, built based on a relaxed structural balance criterion. We found that grazing simplified the structure of the plant community. With increasing stocking rate species with no significant associations became dominant and the number of partitions decreased in the plant community. Independently of stocking rate, many species presented an associative strategy in the plant community because they benefit from the association to certain ‘nurse’ plants. These ‘nurses’ together with species that developed a segregating strategy, intervened in most of the interactions in the community. Ecological networks that combine links with different signs provide a new insight to analyze the structure of natural communities and identify the species which play a central role in them.

Theoretical research and experimental validation of elastic dynamic load spectra on bogie frame of high-speed train

NASA Astrophysics Data System (ADS)

Zhu, Ning; Sun, Shouguang; Li, Qiang; Zou, Hua

2016-05-01

When a train runs at high speeds, the external exciting frequencies approach the natural frequencies of bogie critical components, thereby inducing strong elastic vibrations. The present international reliability test evaluation standard and design criteria of bogie frames are all based on the quasi-static deformation hypothesis. Structural fatigue damage generated by structural elastic vibrations has not yet been included. In this paper, theoretical research and experimental validation are done on elastic dynamic load spectra on bogie frame of high-speed train. The construction of the load series that correspond to elastic dynamic deformation modes is studied. The simplified form of the load series is obtained. A theory of simplified dynamic load-time histories is then deduced. Measured data from the Beijing-Shanghai Dedicated Passenger Line are introduced to derive the simplified dynamic load-time histories. The simplified dynamic discrete load spectra of bogie frame are established. Based on the damage consistency criterion and a genetic algorithm, damage consistency calibration of the simplified dynamic load spectra is finally performed. The computed result proves that the simplified load series is reasonable. The calibrated damage that corresponds to the elastic dynamic discrete load spectra can cover the actual damage at the operating conditions. The calibrated damage satisfies the safety requirement of damage consistency criterion for bogie frame. This research is helpful for investigating the standardized load spectra of bogie frame of high-speed train.

Simplified dispatch-assisted CPR instructions outperform standard protocol.

PubMed

Dias, J A; Brown, T B; Saini, D; Shah, R C; Cofield, S S; Waterbor, J W; Funkhouser, E; Terndrup, T E

2007-01-01

Dispatch-assisted chest compressions only CPR (CC-CPR) has gained widespread acceptance, and recent research suggests that increasing the proportion of compression time during CPR may increase survival from out-of-hospital cardiac arrest. We created a simplified CC-CPR protocol to reduce time to start chest compressions and to increase the proportion of time spent delivering chest compressions. This simplified protocol was compared to a published protocol, Medical Priority Dispatch System (MPDS) Version 11.2, recommended by the National Academies of Emergency Dispatch. Subjects were randomized to the MPDS v11.2 protocol or a simplified protocol. Data was recorded from a Laerdal Resusci Anne Skillreporter manikin. A simulated emergency medical dispatcher, contacted by cell phone, delivered standardized instructions for both protocols. Outcomes included chest compression rate, depth, hand position, full release, overall proportion of compressions without error, time to start of CPR and total hands-off chest time. Proportions were analyzed by Wilcoxon's Rank Sum tests and time variables with Welch ANOVA and Wilcoxon's Rank Sum test. All tests used a two-sided alpha-level of 0.05. One hundred and seventeen subjects were randomized prospectively, 58 to the standard protocol and 59 to the simplified protocol. The average age of subjects in both groups was 25 years old. For both groups, the compression rate was equivalent (104 simplified versus 94 MPDS, p = 0.13), as was the proportion with total release (1.0 simplified versus 1.0 MPDS, p = 0.09). The proportion to the correct depth was greater in the simplified protocol (0.31 versus 0.03, p < 0.01), as was the proportion of compressions done without error (0.05 versus 0.0, p = 0.16). Time to start of chest compressions and total hands-off chest time were better in the simplified protocol (start time 60.9s versus 78.6s, p < 0.0001; hands-off chest time 69 s versus 95 s, p < 0.0001). The proportion with correct hand position, however, was worse in the simplified protocol (0.35 versus 0.84, p < 0.01). The simplified protocol was as good as, or better than the MPDS v11.2 protocol in every aspect studied except hand position, and the simplified protocol resulted in significant time savings. The protocol may need modification to ensure correct hand position. Time savings and improved quality of CPR achieved by the new set of instructions could be important in strengthening critical links in the cardiac chain of survival.

A Simplified Model for the Effect of Weld-Induced Residual Stresses on the Axial Ultimate Strength of Stiffened Plates

NASA Astrophysics Data System (ADS)

Chen, Bai-Qiao; Guedes Soares, C.

2018-03-01

The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies (IACS) Common Structural Rules (CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.

Investigations in a Simplified Bracketed Grid Approach to Metrical Structure

ERIC Educational Resources Information Center

Liu, Patrick Pei

2010-01-01

In this dissertation, I examine the fundamental mechanisms and assumptions of the Simplified Bracketed Grid Theory (Idsardi 1992) in two ways: first, by comparing it with Parametric Metrical Theory (Hayes 1995), and second, by implementing it in the analysis of several case studies in stress assignment and syllabification. Throughout these…

High-pulse-energy mode-locked picosecond oscillator

NASA Astrophysics Data System (ADS)

Chao, Yang; Chen, Meng; Li, Gang

2014-02-01

We report on a high-pulse-energy solid-state picosecond Nd:YVO4 oscillator with cavity-dumping. The laser is end-pumped by an 808 nm laser diode and passively mode-locked with a semiconductor saturable absorption mirror (SESAM). In pure cw-mode-locking, this laser produced 2.5 W of average power at a pulse repetition rate of 40 MHz and pulse duration around 12 ps. A cavity dumping technique using an intra-cavity BBO electro-optic crystal to which bidirectional voltage was applied was adopted, effectively improving the cavity-dumping rate. Tunable high repetition rate from 100 kHz to 1 MHz was achieved. With electro-optic cavity dumper working at 1 MHz repetition rate, we achieved average power 594 mW. The laser includes a 5 mm long, a-cut, 0.5% doped Nd:YVO4 crystal with a 5-degree angle at one end face. Laser radiation is coupled out from the crystal end face with a 5-degree angle, without requiring insertion of a thin-film polarizer (TFP), thus simplifying the laser structure. This picosecond laser system has the advantages of compact structure and high stability, providing a good oscillator for regenerative amplifiers.

Oscillating water column structural model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Copeland, Guild; Bull, Diana L; Jepsen, Richard Alan

2014-09-01

An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by amore » BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.« less

Generalized fictitious methods for fluid-structure interactions: Analysis and simulations

NASA Astrophysics Data System (ADS)

Yu, Yue; Baek, Hyoungsu; Karniadakis, George Em

2013-07-01

We present a new fictitious pressure method for fluid-structure interaction (FSI) problems in incompressible flow by generalizing the fictitious mass and damping methods we published previously in [1]. The fictitious pressure method involves modification of the fluid solver whereas the fictitious mass and damping methods modify the structure solver. We analyze all fictitious methods for simplified problems and obtain explicit expressions for the optimal reduction factor (convergence rate index) at the FSI interface [2]. This analysis also demonstrates an apparent similarity of fictitious methods to the FSI approach based on Robin boundary conditions, which have been found to be very effective in FSI problems. We implement all methods, including the semi-implicit Robin based coupling method, in the context of spectral element discretization, which is more sensitive to temporal instabilities than low-order methods. However, the methods we present here are simple and general, and hence applicable to FSI based on any other spatial discretization. In numerical tests, we verify the selection of optimal values for the fictitious parameters for simplified problems and for vortex-induced vibrations (VIV) even at zero mass ratio ("for-ever-resonance"). We also develop an empirical a posteriori analysis for complex geometries and apply it to 3D patient-specific flexible brain arteries with aneurysms for very large deformations. We demonstrate that the fictitious pressure method enhances stability and convergence, and is comparable or better in most cases to the Robin approach or the other fictitious methods.

A Simplified Technique for Evaluating Human "CCR5" Genetic Polymorphism

ERIC Educational Resources Information Center

Falteisek, Lukáš; Cerný, Jan; Janštová, Vanda

2013-01-01

To involve students in thinking about the problem of AIDS (which is important in the view of nondecreasing infection rates), we established a practical lab using a simplified adaptation of Thomas's (2004) method to determine the polymorphism of HIV co-receptor CCR5 from students' own epithelial cells. CCR5 is a receptor involved in inflammatory…

Inelastic behavior of structural components

NASA Technical Reports Server (NTRS)

Hussain, N.; Khozeimeh, K.; Toridis, T. G.

1980-01-01

A more accurate procedure was developed for the determination of the inelastic behavior of structural components. The actual stress-strain curve for the mathematical of the structure was utilized to generate the force-deformation relationships for the structural elements, rather than using simplified models such as elastic-plastic, bilinear and trilinear approximations. relationships were generated for beam elements with various types of cross sections. In the generational of these curves, stress or load reversals, kinematic hardening and hysteretic behavior were taken into account. Intersections between loading and unloading branches were determined through an iterative process. Using the inelastic properties obtained, the plastic static response of some simple structural systems composed of beam elements was computed. Results were compared with known solutions, indicating a considerable improvement over response predictions obtained by means of simplified approximations used in previous investigations.

42 CFR 413.321 - Simplified cost report for SNFs.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES; OPTIONAL PROSPECTIVELY DETERMINED PAYMENT RATES FOR SKILLED NURSING FACILITIES Prospectively Determined Payment Rates for Low-Volume Skilled Nursing Facilities, for Cost Reporting Periods Beginning...

42 CFR 413.321 - Simplified cost report for SNFs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... SERVICES; OPTIONAL PROSPECTIVELY DETERMINED PAYMENT RATES FOR SKILLED NURSING FACILITIES Prospectively Determined Payment Rates for Low-Volume Skilled Nursing Facilities, for Cost Reporting Periods Beginning...

78 FR 44459 - Rate Regulation Reforms

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-24

... the interest rate. A simple multiplication of the nominal rate by the portion of the year covered by... makes technical changes to the full and simplified rate procedures; changes the interest rate that... allocation methodology for cross-over traffic. Part IV sets out the change in the interest rate carriers must...

A Simplified Method for Tissue Engineering Skeletal Muscle Organoids in Vitro

NASA Technical Reports Server (NTRS)

Shansky, Janet; DelTatto, Michael; Chromiak, Joseph; Vandenburgh, Herman

1996-01-01

Tissue-engineered three dimensional skeletal muscle organ-like structures have been formed in vitro from primary myoblasts by several different techniques. This report describes a simplified method for generating large numbers of muscle organoids from either primary embryonic avian or neonatal rodent myoblasts, which avoids the requirements for stretching and other mechanical stimulation.

Dynamic characteristics and simplified numerical methods of an all-vertical-piled wharf in offshore deep water

NASA Astrophysics Data System (ADS)

Zhang, Hua-qing; Sun, Xi-ping; Wang, Yuan-zhan; Yin, Ji-long; Wang, Chao-yang

2015-10-01

There has been a growing trend in the development of offshore deep-water ports in China. For such deep sea projects, all-vertical-piled wharves are suitable structures and generally located in open waters, greatly affected by wave action. Currently, no systematic studies or simplified numerical methods are available for deriving the dynamic characteristics and dynamic responses of all-vertical-piled wharves under wave cyclic loads. In this article, we compare the dynamic characteristics of an all-vertical-piled wharf with those of a traditional inshore high-piled wharf through numerical analysis; our research reveals that the vibration period of an all-vertical-piled wharf under cyclic loading is longer than that of an inshore high-piled wharf and is much closer to the period of the loading wave. Therefore, dynamic calculation and analysis should be conducted when designing and calculating the characteristics of an all-vertical-piled wharf. We establish a dynamic finite element model to examine the dynamic response of an all-vertical-piled wharf under wave cyclic loads and compare the results with those under wave equivalent static load; the comparison indicates that dynamic amplification of the structure is evident when the wave dynamic load effect is taken into account. Furthermore, a simplified dynamic numerical method for calculating the dynamic response of an all-vertical-piled wharf is established based on the P-Y curve. Compared with finite element analysis, the simplified method is more convenient to use and applicable to large structural deformation while considering the soil non-linearity. We confirmed that the simplified method has acceptable accuracy and can be used in engineering applications.

Advanced low-activation materials. Fibre-reinforced ceramic composites

NASA Astrophysics Data System (ADS)

Fenici, P.; Scholz, H. W.

1994-09-01

A serious safety and environmental concern for thermonuclear fusion reactor development regards the induced radioactivity of the first wall and structural components. The use of low-activation materials (LAM) in a demonstration reactor would reduce considerably its potential risk and facilitate its maintenance. Moreover, decommissioning and waste management including disposal or even recycling of structural materials would be simplified. Ceramic fibre-reinforced SiC materials offer highly appreciable low activation characteristics in combination with good thermomechanical properties. This class of materials is now under experimental investigation for structural application in future fusion reactors. An overview on the recent results is given, covering coolant leak rates, thermophysical properties, compatibility with tritium breeder materials, irradiation effects, and LAM-consistent purity. SiC/SiC materials present characteristics likely to be optimised in order to meet the fusion application challenge. The scope is to put into practice the enormous potential of inherent safety with fusion energy.

Research on Bell-Shaped Vibratory Angular Rate Gyro's Character of Resonator

PubMed Central

Su, Zhong; Fu, Mengyin; Li, Qing; Liu, Ning; Liu, Hong

2013-01-01

Bell-shaped vibratory angular rate gyro (abbreviated as BVG) is a new type Coriolis vibratory gyro that was inspired by Chinese traditional clocks. The resonator fuses based on a variable thickness axisymmetric multicurved surface shell. Its characteristics can directly influence the performance of BVG. The BVG structure not only has capabilities of bearing high overload, high impact and, compared with the tuning fork, vibrating beam, shell and a comb structure, but also a higher frequency to overcome the influence of the disturbance of the exterior environment than the same sized hemispherical resonator gyroscope (HRG) and the traditional cylinder vibratory gyroscope. It can be widely applied in high dynamic low precision angular rate measurement occasions. The main work is as follows: the issue mainly analyzes the structure and basic principle, and investigates the bell-shaped resonator's mathematical model. The reasonable structural parameters are obtained from finite element analysis and an intelligent platform. Using the current solid vibration gyro theory analyzes the structural characteristics and principles of BVG. The bell-shaped resonator is simplified as a paraboloid of the revolution mechanical model, which has a fixed closed end and a free opened end. It obtains the natural frequency and vibration modes based on the theory of elasticity. The structural parameters are obtained from the orthogonal method by the research on the structural parameters of the resonator analysis. It obtains the modal analysis, stress analysis and impact analysis with the chosen parameters. Finally, using the turntable experiment verifies the gyro effect of the BVG. PMID:23575033

Comparison of Observed Spatio-temporal Aftershock Patterns with Earthquake Simulator Results

NASA Astrophysics Data System (ADS)

Kroll, K.; Richards-Dinger, K. B.; Dieterich, J. H.

2013-12-01

Due to the complex nature of faulting in southern California, knowledge of rupture behavior near fault step-overs is of critical importance to properly quantify and mitigate seismic hazards. Estimates of earthquake probability are complicated by the uncertainty that a rupture will stop at or jump a fault step-over, which affects both the magnitude and frequency of occurrence of earthquakes. In recent years, earthquake simulators and dynamic rupture models have begun to address the effects of complex fault geometries on earthquake ground motions and rupture propagation. Early models incorporated vertical faults with highly simplified geometries. Many current studies examine the effects of varied fault geometry, fault step-overs, and fault bends on rupture patterns; however, these works are limited by the small numbers of integrated fault segments and simplified orientations. The previous work of Kroll et al., 2013 on the northern extent of the 2010 El Mayor-Cucapah rupture in the Yuha Desert region uses precise aftershock relocations to show an area of complex conjugate faulting within the step-over region between the Elsinore and Laguna Salada faults. Here, we employ an innovative approach of incorporating this fine-scale fault structure defined through seismological, geologic and geodetic means in the physics-based earthquake simulator, RSQSim, to explore the effects of fine-scale structures on stress transfer and rupture propagation and examine the mechanisms that control aftershock activity and local triggering of other large events. We run simulations with primary fault structures in state of California and northern Baja California and incorporate complex secondary faults in the Yuha Desert region. These models produce aftershock activity that enables comparison between the observed and predicted distribution and allow for examination of the mechanisms that control them. We investigate how the spatial and temporal distribution of aftershocks are affected by changes to model parameters such as shear and normal stress, rate-and-state frictional properties, fault geometry, and slip rate.

A comparison between simplified and intensive dose-titration algorithms using AIR inhaled insulin for insulin-naive patients with type 2 diabetes in a randomized noninferiority trial.

PubMed

Mathieu, C; Cuddihy, R; Arakaki, R F; Belin, R M; Planquois, J-M; Lyons, J N; Heilmann, C R

2009-09-01

Insulin initiation and optimization is a challenge for patients with type 2 diabetes. Our objective was to determine whether safety and efficacy of AIR inhaled insulin (Eli Lilly and Co., Indianapolis, IN) (AIR is a registered trademark of Alkermes, Inc., Cambridge, MA) using a simplified regimen was noninferior to an intensive regimen. This was an open-label, randomized study in insulin-naive adults not optimally controlled by oral antihyperglycemic medications. Simplified titration included a 6 U per meal AIR insulin starting dose. Individual doses were adjusted at mealtime in 2-U increments from the previous day's four-point self-monitored blood glucose (SMBG) (total < or =6 U). Starting Air insulin doses for intensive titration were based on fasting blood glucose, gender, height, and weight. Patients conducted four-point SMBG daily for the study duration. Insulin doses were titrated based on the previous 3 days' mean SMBG (total < or =8 U). End point hemoglobin A1C (A1C) was 7.07 +/- 0.09% and 6.87 +/- 0.09% for simplified (n = 178) and intensive (n = 180) algorithms, respectively. Noninferiority between algorithms was not established. The fasting blood glucose (least squares mean +/- standard error) values for the simplified (137.27 +/- 3.42 mg/dL) and intensive (133.13 +/- 3.42 mg/dL) algorithms were comparable. Safety profiles were comparable. The hypoglycemic rate at 4, 8, 12, and 24 weeks was higher in patients receiving intensive titration (all P < .0001). The nocturnal hypoglycemic rate for patients receiving intensive titration was higher than for those receiving simplified titration at 8 (P < 0.015) and 12 weeks (P < 0.001). Noninferiority between the algorithms, as measured by A1C, was not demonstrated. This finding re-emphasizes the difficulty of identifying optimal, simplified insulin regimens for patients.

Early Efficacy Analysis of Biatrial Ablation versus Left and Simplified Right Atrial Ablation for Atrial Fibrillation Treatment in Patients with Rheumatic Heart Disease.

PubMed

Liu, Hong; Chen, Lin; Xiao, Yingbin; Ma, Ruiyan; Hao, Jia; Chen, Baicheng; Qin, Chuan; Cheng, Wei

2015-08-01

Atrial fibrillation (AF) is the most common sustained arrhythmia. About 60% of patients with rheumatic heart disease have persistent AF. A total of 197 patients underwent valve replacement concomitant bipolar radiofrequency ablation (BRFA). Patients were divided into the biatrial ablation group and the simplified right atrial ablation group. In biatrial ablation group, the patients underwent a complete left and right atrial ablation. In simplified right atrial ablation group, the patients underwent a complete left atrial ablation and a simplified right atrial ablation. The conversion of sinus rhythm (SR) was high in both groups during the follow-up period. In the simplified right atrial ablation group, SR conversion rate was 88.29% at discharge. At six months and 12 months after surgery, 87.39% of patients and 86.49% of patients were in SR free of antiarrhythmic drugs, respectively. While in the biatrial ablation group, SA conversion rate was 89.53% at discharge. Percentage of patients in SR free of antiarrhythmic drugs was 88.37% and 88.37% at six months and 12 months after surgery, respectively. Echocardiography showed left atrial diameter decreased significantly after the surgery in the two groups. The ejection fraction and fractional shortening were improved significantly, without significant differences between the two groups. The results suggest that the concomitant left atrial and simplified right atrial BRFA for AF in patients undergoing valve replacement can achieve similar early efficiency as biatrial ablation. Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Putting proteins back into water

NASA Astrophysics Data System (ADS)

de Los Rios, Paolo; Caldarelli, Guido

2000-12-01

We introduce a simplified protein model where the solvent (water) degrees of freedom appear explicitly (although in an extremely simplified fashion). Using this model we are able to recover the thermodynamic phenomenology of proteins over a wide range of temperatures. In particular we describe both the warm and the cold protein denaturation within a single framework, while addressing important issues about the structure of model proteins.

Earplug rankings based on the protector-attenuation rating (P-AR).

DOT National Transportation Integrated Search

1975-01-01

Forty-five attenuation spectra for earplugs were classified according to a simplified method designed to produce single-number ratings of noise reduction. The rating procedure was applied to the mean attenuation scores, to mean-minus-one-standard-dev...

Studies on the S-band bunching system with the Hybrid Bunching-accelerating Structure

NASA Astrophysics Data System (ADS)

Pei, Shi-Lun; Gao, Bin

2018-04-01

Generally, a standard bunching system is composed of a standing-wave (SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure. In the industrial area, the bunching system is usually simplified by eliminating the PB and integrating the B and the standard accelerating structure together to form a β-varied accelerating structure. The beam capturing efficiency for this kind of simplified system is often worse than that for the standard one. The hybrid buncher (HB) has been proved to be a successful attempt to reduce the cost but preserve the beam quality as much as possible. Here we propose to exclusively simplify the standard bunching system by integrating the PB, the B and the standard accelerating structure together to form a Hybrid Bunching-accelerating Structure (HBaS). Compared to the standard bunching system, the one based on the HBaS is more compact, and the cost is lowered to the largest extent. With almost the same beam transportation efficiency (∼70%) from the electron gun to the linac exit, the peak-to-peak (p-to-p) beam energy spread and the 1 σ emittance of the linac with the HBaS are ∼20% and ∼60% bigger than those of the linac based on the split PB/B/standard accelerating structure system. Nonetheless, the proposed HBaS can be widely applied in the industrial linacs to greatly increase the beam capturing efficiency without fairly increasing the construction cost.

Stand, species, and individual traits impact transpiration in historically disturbed forests.

NASA Astrophysics Data System (ADS)

Blakely, B.; Rocha, A. V.; McLachlan, J. S.

2017-12-01

Historic logging disturbances have changed the structure and species composition of most Northern temperate forests. These changes impact the process of transpiration - which in turn impacts canopy surface temperature - but the links among structure, composition, and transpiration remain unclear. For this reason, ecosystem models typically use simplified structure and composition to simulate the impact of disturbances on forest transpiration. However, such simplifications ignore real variability among stands, species, and individual trees that may strongly influence transpiration across spatial and temporal scales. To capture this variability, we monitored transpiration in 48 individual trees of multiple species in both undisturbed (400+ yr) and historically logged (80 - 120 yr) forests. Using modern and historic forest surveys, we upscaled our observations to stand and regional scales to identify the key changes impacting transpiration. We extended these inferences by establishing a relationship between transpiration and measured surface temperature, linking disturbance-induced changes in structure and composition to local and regional climate. Despite greater potential evapotranspiration and basal area, undisturbed forest transpired less than disturbed (logged) forest. Transpiration was a strong predictor of surface temperature, and the canopy surface was warmer in undisturbed forest. Transpiration differences among disturbed and undisturbed forests resulted from (1) lesser transpiration and dampened seasonality in evergreen species (2) greater transpiration in younger individuals within a species, and (3) strong transpiration by large individuals. When transpiration was scaled to the stand or regional level in a simplified manner (e.g. a single transpiration rate for all deciduous individuals), the resulting estimates differed markedly from the original. Stand- species- and individual-level traits are therefore essential for understanding how transpiration and surface temperature respond to disturbance. Without consideration of such traits, current ecosystem models may struggle to capture the true impact of logging disturbances on forest transpiration.

Position Corrections for Airspeed and Flow Angle Measurements on Fixed-Wing Aircraft

NASA Technical Reports Server (NTRS)

Grauer, Jared A.

2017-01-01

This report addresses position corrections made to airspeed and aerodynamic flow angle measurements on fixed-wing aircraft. These corrections remove the effects of angular rates, which contribute to the measurements when the sensors are installed away from the aircraft center of mass. Simplified corrections, which are routinely used in practice and assume small flow angles and angular rates, are reviewed. The exact, nonlinear corrections are then derived. The simplified corrections are sufficient in most situations; however, accuracy diminishes for smaller aircraft that incur higher angular rates, and for flight at high air flow angles. This is demonstrated using both flight test data and a nonlinear flight dynamics simulation of a subscale transport aircraft in a variety of low-speed, subsonic flight conditions.

Simplified Life-Cycle Cost Estimation

NASA Technical Reports Server (NTRS)

Remer, D. S.; Lorden, G.; Eisenberger, I.

1983-01-01

Simple method for life-cycle cost (LCC) estimation avoids pitfalls inherent in formulations requiring separate estimates of inflation and interest rates. Method depends for validity observation that interest and inflation rates closely track each other.

Microplate and shear zone models for oceanic spreading center reorganizations

NASA Technical Reports Server (NTRS)

Engeln, Joseph F.; Stein, Seth; Werner, John; Gordon, Richard

1988-01-01

The kinematics of rift propagation and the resulting goemetries of various tectonic elements for two plates is reviewed with no overlap zone. The formation and evolution of overlap regions using schematic models is discussed. The models are scaled in space and time to approximate the Easter plate, but are simplified to emphasize key elements. The tectonic evolution of overlap regions which act as rigid microplates and shear zones is discussed, and the use of relative motion and structural data to discriminate between the two types of models is investigated. The effect of propagation rate and rise time on the size, shape, and deformation of the overlap region is demonstrated.

Coherent or hopping like energy transfer in the chlorosome ?

NASA Astrophysics Data System (ADS)

Nalbach, Peter

2014-08-01

Chlorosomes, as part of the light-harvesting system of green bacteria, are the largest and most efficient antennae systems in nature. We have studied energy transfer dynamics in the chlorosome in a simplified toy model employing a master equation. Dephasing and relaxation due to environmental fluctuations are included by Lindblad dephasing and Redfield thermalization rates. We find at room temperature three separate time scales, i.e. 25 fs, 250 fs and 2.5 ps and determine the according energy pathways through the hierarchical structure in the chlorosome. Quantum coherence lives up to 150 fs at which time the energy is spread over roughly 12 pigments in our model.

An Analytical Solution for Transient Thermal Response of an Insulated Structure

NASA Technical Reports Server (NTRS)

Blosser, Max L.

2012-01-01

An analytical solution was derived for the transient response of an insulated aerospace vehicle structure subjected to a simplified heat pulse. This simplified problem approximates the thermal response of a thermal protection system of an atmospheric entry vehicle. The exact analytical solution is solely a function of two non-dimensional parameters. A simpler function of these two parameters was developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Using these techniques, the maximum structural temperature rise was calculated using the analytical solutions and shown to typically agree with finite element simulations within 10 to 20 percent over the relevant range of parameters studied.

Simplified nonplanar wafer bonding for heterogeneous device integration

NASA Astrophysics Data System (ADS)

Geske, Jon; Bowers, John E.; Riley, Anton

2004-07-01

We demonstrate a simplified nonplanar wafer bonding technique for heterogeneous device integration. The improved technique can be used to laterally integrate dissimilar semiconductor device structures on a lattice-mismatched substrate. Using the technique, two different InP-based vertical-cavity surface-emitting laser active regions have been integrated onto GaAs without compromising the quality of the photoluminescence. Experimental and numerical simulation results are presented.

Space Fabrication Demonstration System

NASA Technical Reports Server (NTRS)

1977-01-01

Progress on fabrication facility (beam builder) support structure control, clamp/weld block, and welding and truss cut off is discussed. The brace attachment design was changed and the design of the weld mechanism was modified which achieved the following system benefits: (1) simplified weld electrode life; (2) reduced weld power requirements; and (3) simplified brace attachment mechanisms. Static and fatigue characteristics of spot welded 2024T3 aluminum joints are evaluated.

Causal Learning with Local Computations

ERIC Educational Resources Information Center

Fernbach, Philip M.; Sloman, Steven A.

2009-01-01

The authors proposed and tested a psychological theory of causal structure learning based on local computations. Local computations simplify complex learning problems via cues available on individual trials to update a single causal structure hypothesis. Structural inferences from local computations make minimal demands on memory, require…

Research on Darrieus-type hydraulic turbine for extra-low head hydropower utilization

NASA Astrophysics Data System (ADS)

Furukawa, A.; Watanabe, S.; Okuma, K.

2012-11-01

A Darrieus-type turbine has been investigated for extra-low head hydropower utilization. In the present paper, authors'research on Darrieus-type hydraulic turbine is briefly reviewed. The working principle of Darrieus turbine is explained with advantage of its simple structure, at first. Then the fluid-dynamic difference between rotating and linear motions of a blade in a uniform flow is clarified with guiding principle of high performance design of Darrieus turbine. Cavitation problem is also described. Next, effects of duct-casing, consisting of an intake, runner section and draft tube, are discussed and a simplified structure of Darrieus turbine is shown by installing the inlet nozzle. Finally, in the practical use, an adjustment of inlet nozzle section by lowering the inlet nozzle height is proposed when flow rate is varied temporally and seasonally.

Influences of strain rate on yield strength aluminum alloys

NASA Astrophysics Data System (ADS)

Rizal, Samsul; Firdaus, Hamdani Teuku; Thaib, Razali; Homma, Hiroomi

2005-04-01

The simulation of aircraft has often been performing by implementing finite element code on supercomputers. The reliability an accuracy of simulation depends mainly on the material model as well as on structural model used in calculations. Consequently, an accurate knowledge of mechanical behavior of materials under impact loading is essential for safety performance evaluation of structure. Impact tension tests on specimens for aircrafts and automotive structural applications are conduct by means of the split Hopkinson bar apparatus. Small specimens having diameter 4 mm are use in the test. Tensile stress-strain relations at strain rates of 102 s-1 to over 103 s-1 are present and compared with those obtained at quasi-static strain rates. The limitations on the applicability of apparatus are also discusses. The other importance of the reference of strain, while studying void growth in elastic-viscoplastic material, is emphasized. In the present paper, a simplified plane-symmetrical two-dimensional finite element model for a SHPB with a plate specimen made of an elastic material is first established. The used of strain gage mounted at the specimens to be monitored strain during the course of impact test. Comparisons may then be made between the numerical predicted and experimentally observed of load and a specimen strain. This report also describes the apparatus and instrumentation, and also be discusses the advantages and limitations of experimental technique. Fractograph is taken by scanning electron microscope on the center of the specimens for judgment of the fracture mechanism and strain rates influences on the materials.

Quick and Easy Rate Equations for Multistep Reactions

ERIC Educational Resources Information Center

Savage, Phillip E.

2008-01-01

Students rarely see closed-form analytical rate equations derived from underlying chemical mechanisms that contain more than a few steps unless restrictive simplifying assumptions (e.g., existence of a rate-determining step) are made. Yet, work published decades ago allows closed-form analytical rate equations to be written quickly and easily for…

29 CFR 548.100 - Introductory statement.

Code of Federal Regulations, 2010 CFR

2010-07-01

... simplify bookkeeping and computation of overtime pay. 1 The regular rate is the average hourly earnings of... AUTHORIZATION OF ESTABLISHED BASIC RATES FOR COMPUTING OVERTIME PAY Interpretations Introduction § 548.100... requirements of computing overtime pay at the regular rate, 1 and to allow, under specific conditions, the use...

Numerical Approximation of Elasticity Tensor Associated With Green-Naghdi Rate.

PubMed

Liu, Haofei; Sun, Wei

2017-08-01

Objective stress rates are often used in commercial finite element (FE) programs. However, deriving a consistent tangent modulus tensor (also known as elasticity tensor or material Jacobian) associated with the objective stress rates is challenging when complex material models are utilized. In this paper, an approximation method for the tangent modulus tensor associated with the Green-Naghdi rate of the Kirchhoff stress is employed to simplify the evaluation process. The effectiveness of the approach is demonstrated through the implementation of two user-defined fiber-reinforced hyperelastic material models. Comparisons between the approximation method and the closed-form analytical method demonstrate that the former can simplify the material Jacobian evaluation with satisfactory accuracy while retaining its computational efficiency. Moreover, since the approximation method is independent of material models, it can facilitate the implementation of complex material models in FE analysis using shell/membrane elements in abaqus.

Essential core of the Hawking–Ellis types

NASA Astrophysics Data System (ADS)

Martín-Moruno, Prado; Visser, Matt

2018-06-01

The Hawking–Ellis (Segre–Plebański) classification of possible stress–energy tensors is an essential tool in analyzing the implications of the Einstein field equations in a more-or-less model-independent manner. In the current article the basic idea is to simplify the Hawking–Ellis type I, II, III, and IV classification by isolating the ‘essential core’ of the type II, type III, and type IV stress–energy tensors; this being done by subtracting (special cases of) type I to simplify the (Lorentz invariant) eigenvalue structure as much as possible without disturbing the eigenvector structure. We will denote these ‘simplified cores’ type II0, type III0, and type IV0. These ‘simplified cores’ have very nice and simple algebraic properties. Furthermore, types I and II0 have very simple classical interpretations, while type IV0 is known to arise semi-classically (in renormalized expectation values of standard stress–energy tensors). In contrast type III0 stands out in that it has neither a simple classical interpretation, nor even a simple semi-classical interpretation. We will also consider the robustness of this classification considering the stability of the different Hawking–Ellis types under perturbations. We argue that types II and III are definitively unstable, whereas types I and IV are stable.

Simplified Calculation Model and Experimental Study of Latticed Concrete-Gypsum Composite Panels

PubMed Central

Jiang, Nan; Ma, Shaochun

2015-01-01

In order to address the performance complexity of the various constituent materials of (dense-column) latticed concrete-gypsum composite panels and the difficulty in the determination of the various elastic constants, this paper presented a detailed structural analysis of the (dense-column) latticed concrete-gypsum composite panel and proposed a feasible technical solution to simplified calculation. In conformity with mechanical rules, a typical panel element was selected and divided into two homogenous composite sub-elements and a secondary homogenous element, respectively for solution, thus establishing an equivalence of the composite panel to a simple homogenous panel and obtaining the effective formulas for calculating the various elastic constants. Finally, the calculation results and the experimental results were compared, which revealed that the calculation method was correct and reliable and could meet the calculation needs of practical engineering and provide a theoretical basis for simplified calculation for studies on composite panel elements and structures as well as a reference for calculations of other panels. PMID:28793631

[Authorization, translation, back translation and language modification of the simplified Chinese adult comorbidity-27 index].

PubMed

Gao, L; Mao, C; Yu, G Y; Peng, X

2016-10-09

Objective: To translate the adult comorbidity evaluation-27(ACE-27) index authored by professor JF Piccirillo into Chinese and for the purpose of assessing the possible impact of comorbidity on survival of oral cancer patients and improving cancer staging. Methods: The translation included the following steps, obtaining permission from professor Piccirillo, translation, back translation, language modification, adjusted by the advice from the professors of oral and maxillofacial surgery. The test population included 154 patients who were admitted to Peking University of Stomatology during March 2011. Questionnaire survey was conducted on these patients. Retest of reliability, internal consistency reliability, content validity, and structure validity were performed. Results: The simplified Chinese ACE-27 index was established. The Cronbach's α was 0.821 in the internal consistency reliability test. The Kaiser-Meyer-Olkin (KMO) value of 8 items was 0.859 in the structure validity test. Conclusions: The simplified Chinese ACE-27 index has good feasibility and reliability. It is useful to assess the comorbidity of oral cancer patients.

Simplified Calculation Model and Experimental Study of Latticed Concrete-Gypsum Composite Panels.

PubMed

Jiang, Nan; Ma, Shaochun

2015-10-27

In order to address the performance complexity of the various constituent materials of (dense-column) latticed concrete-gypsum composite panels and the difficulty in the determination of the various elastic constants, this paper presented a detailed structural analysis of the (dense-column) latticed concrete-gypsum composite panel and proposed a feasible technical solution to simplified calculation. In conformity with mechanical rules, a typical panel element was selected and divided into two homogenous composite sub-elements and a secondary homogenous element, respectively for solution, thus establishing an equivalence of the composite panel to a simple homogenous panel and obtaining the effective formulas for calculating the various elastic constants. Finally, the calculation results and the experimental results were compared, which revealed that the calculation method was correct and reliable and could meet the calculation needs of practical engineering and provide a theoretical basis for simplified calculation for studies on composite panel elements and structures as well as a reference for calculations of other panels.

A simplified method of evaluating the stress wave environment of internal equipment

NASA Technical Reports Server (NTRS)

Colton, J. D.; Desmond, T. P.

1979-01-01

A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.

Environmental analysis Waste Isolation Pilot Plant (WIPP) cost reduction proposals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The Waste Isolation Pilot Plant (WIPP) is a research and development facility to demonstrate the safe disposal of radioactive wastes resulting from the defense activities and programs of the United States government. The facility is planned to be developed in bedded salt at the Los Medanos site in southeastern New Mexico. The environmental consequences of contruction and operation of the WIPP facility are documented in ''Final Environmental Impact Statement, Waste Isolation Pilot Plant''. The proposed action addressed by this environmental analysis is to simplify and reduce the scope of the WIPP facility as it is currently designed. The proposed changesmore » to the existing WIPP design are: limit the waste storage rate to 500,000 cubic feet per year; eliminate one shaft and revise the underground ventilation system; eliminate the underground conveyor system; combine the Administration Building, the Underground Personnel Building and the Waste Handling Building office area; simplify the central monitoring system; simplify the security control systems; modify the Waste Handling Building; simplify the storage exhaust system; modify the above ground salt handling logistics; simplify the power system; reduce overall site features; simplify the Warehouse/Shops Building and eliminate the Vehicle Maintenance Building; and allow resource recovery in Control Zone IV.« less

Development and Validation of the Implicit Information from Lewis Structures Instrument(IILSI): Do Students Connect Structures with Properties?

ERIC Educational Resources Information Center

Cooper, Melanie M.; Underwood, Sonia M.; Hilley, Caleb Z.

2012-01-01

Lewis structures are a simplified two dimensional "cartoon" of molecular structure that allow a knowledgeable user to predict the types of properties a particular substance may exhibit. However, prior research shows that many students fail to recognize these structure-property connections and are unable to decode the information…

Structural (Performance) class Potential for North America

Treesearch

Eric Jones; David E. Kretschmann; Kevin Cheung

2014-01-01

Structural class systems are species-independent product classification systems for structural timber. They are used throughout the world to reduce the number of species and grade choices that face the designer of wood construction projects. Structural class systems offer an opportunity to simplify timber specification in North America and to encourage more effective...

The Structural Algebra Option: A Discussion Paper.

ERIC Educational Resources Information Center

Kirshner, David

The goal of this paper is to renew interest in the structural option to algebra instruction. Concern for the usual secondary school algebra curriculum related to simplifying expressions, solving equations, and rationalizing numerators and denominators is viewed from three pedagogical approaches: (1) structural approach, (2) empirical approach, and…

Scalable Video Transmission Over Multi-Rate Multiple Access Channels

DTIC Science & Technology

2007-06-01

Rate - compatible punctured convolutional codes (RCPC codes ) and their ap- plications,” IEEE...source encoded using the MPEG-4 video codec. The source encoded bitstream is then channel encoded with Rate Compatible Punctured Convolutional (RCPC...Clark, and J. M. Geist, “ Punctured convolutional codes or rate (n-1)/n and simplified maximum likelihood decoding,” IEEE Transactions on

Thermoelectric refrigerator

NASA Technical Reports Server (NTRS)

Park, Brian V. (Inventor); Smith, Jr., Malcolm C. (Inventor); McGrath, Ralph D. (Inventor); Gilley, Michael D. (Inventor); Criscuolo, Lance (Inventor); Nelson, John L. (Inventor)

1996-01-01

A refrigerator is provided which combines the benefits of superinsulation materials with thermoelectric devices and phase change materials to provide an environmentally benign system that is energy efficient and can maintain relatively uniform temperatures for extended periods of time with relatively low electrical power requirements. The refrigerator includes a thermoelectric assembly having a thermoelectric device with a hot sink and a cold sink. The superinsulation materials include a plurality of vacuum panels. The refrigerator is formed from an enclosed structure having a door. The vacuum panels may be contained within the walls of the enclosed structure and the door. By mounting the thermoelectric assembly on the door, the manufacturer of the enclosed structure is simplified and the overall R rating of the refrigerator increased. Also an electrical motor and propellers may be mounted on the door to assist in the circulation of air to improve the efficiency of the cold sink and the hot sink. A propeller and/or impeller is preferably mounted within the refrigerator to assist in establishing the desired air circulation flow path.

Reaction of positronium with doped ions in silica-based glasses in the size determination of subnanometer structural open spaces

NASA Astrophysics Data System (ADS)

Inoue, K.; Kataoka, H.; Nagai, Y.; Hasegawa, M.; Kobayashi, Y.

2013-10-01

Positron annihilation spectroscopy is employed to estimate the size of subnanometer-scale open spaces in insulating materials. In most cases, the size is estimated from the lifetime of long-lived ortho-positronium (o-Ps) by pickoff annihilation using a simplified model. However, reactions of Ps with surrounding electrons other than the pickoff reaction, such as spin conversion or chemical reaction, could give a substantially underestimated size using the simplified model. In the present paper, we report that the size of the open spaces can be evaluated correctly by the angular correlation of positron annihilation radiation (ACAR) with a magnetic field using the spin-polarization effect on Ps formation, even if such reactions of Ps occur in the material. This method is applied to the subnanometer-scale structural open spaces of silica-based glass doped with Fe. We demonstrate the influence of the Ps reaction on size-estimation of the open spaces from the o-Ps lifetime. Furthermore, the type of reaction, whether spin conversion or chemical, is distinguished from the magnetic field dependence of the Ps self-annihilation component intensity in the ACAR spectra. The Ps reaction in silica-based glass doped with Fe is a chemical reaction (most likely oxidation) rather than spin conversion, with Fe ions. The chemical quenching rate with Fe ions is determined from the dependence of the o-Ps lifetime on the Fe content.

A simplified fracture network model for studying the efficiency of a single well semi open loop heat exchanger in fractured crystalline rock

NASA Astrophysics Data System (ADS)

de La Bernardie, Jérôme; de Dreuzy, Jean-Raynald; Bour, Olivier; Thierion, Charlotte; Ausseur, Jean-Yves; Lesuer, Hervé; Le Borgne, Tanguy

2016-04-01

Geothermal energy is a renewable energy source particularly attractive due to associated low greenhouse gas emission rates. Crystalline rocks are in general considered of poor interest for geothermal applications at shallow depths (< 100m), because of the low permeability of the medium. In some cases, fractures may enhance permeability, but thermal energy storage at these shallow depths is still remaining very challenging because of the complexity of fractured media. The purpose of this study is to test the possibility of efficient thermal energy storage in shallow fractured rocks with a single well semi open loop heat exchanger (standing column well). For doing so, a simplified numerical model of fractured media is considered with few fractures. Here we present the different steps for building the model and for achieving the sensitivity analysis. First, an analytical and dimensional study on the equations has been achieved to highlight the main parameters that control the optimization of the system. In a second step, multiphysics software COMSOL was used to achieve numerical simulations in a very simplified model of fractured media. The objective was to test the efficiency of such a system to store and recover thermal energy depending on i) the few parameters controlling fracture network geometry (size and number of fractures) and ii) the frequency of cycles used to store and recover thermal energy. The results have then been compared to reference shallow geothermal systems already set up for porous media. Through this study, relationships between structure, heat exchanges and storage may be highlighted.

Opiate Users' Perceived Barriers Against Attending Methadone Maintenance Therapy: A Qualitative Study in China

PubMed Central

Lin, Chunqing; Wu, Zunyou; Detels, Roger

2012-01-01

Methadone maintenance therapy (MMT) in China is facing challenges such as high relapse rates and low coverage. The study assessed factors influencing MMT utilization among opiate users. In-depth interviews were conducted among 30 opiate users in 2008 to ascertain the barriers against seeking MMT. Data were analyzed using ATLAS.ti. Barriers to the treatment included requirement of registration with police, perceived discrimination, logistic difficulties, side effects, fear of being addicted to another drug, lack of additional services, and economic burden. The result suggests the need for structural changes such as improving comprehensive services, simplifying application procedure, and enhancing referral system. The study's limitations are noted. PMID:21417558

Creating 3D Physical Models to Probe Student Understanding of Macromolecular Structure

ERIC Educational Resources Information Center

Cooper, A. Kat; Oliver-Hoyo, M. T.

2017-01-01

The high degree of complexity of macromolecular structure is extremely difficult for students to process. Students struggle to translate the simplified two-dimensional representations commonly used in biochemistry instruction to three-dimensional aspects crucial in understanding structure-property relationships. We designed four different physical…

[Influence of trabecular microstructure modeling on finite element analysis of dental implant].

PubMed

Shen, M J; Wang, G G; Zhu, X H; Ding, X

2016-09-01

To analyze the influence of trabecular microstructure modeling on the biomechanical distribution of implant-bone interface with a three-dimensional finite element mandible model of trabecular structure. Dental implants were embeded in the mandibles of a beagle dog. After three months of the implant installation, the mandibles with dental implants were harvested and scaned by micro-CT and cone-beam CT. Two three-dimensional finite element mandible models, trabecular microstructure(precise model) and macrostructure(simplified model), were built. The values of stress and strain of implant-bone interface were calculated using the software of Ansys 14.0. Compared with the simplified model, the precise models' average values of the implant bone interface stress increased obviously and its maximum values did not change greatly. The maximum values of quivalent stress of the precise models were 80% and 110% of the simplified model and the average values were 170% and 290% of simplified model. The maximum and average values of equivalent strain of precise models were obviously decreased, and the maximum values of the equivalent effect strain were 17% and 26% of simplified model and the average ones were 21% and 16% of simplified model respectively. Stress and strain concentrations at implant-bone interface were obvious in the simplified model. However, the distributions of stress and strain were uniform in the precise model. The precise model has significant effect on the distribution of stress and strain at implant-bone interface.

Quantitative method of medication system interface evaluation.

PubMed

Pingenot, Alleene Anne; Shanteau, James; Pingenot, James D F

2007-01-01

The objective of this study was to develop a quantitative method of evaluating the user interface for medication system software. A detailed task analysis provided a description of user goals and essential activity. A structural fault analysis was used to develop a detailed description of the system interface. Nurses experienced with use of the system under evaluation provided estimates of failure rates for each point in this simplified fault tree. Means of estimated failure rates provided quantitative data for fault analysis. Authors note that, although failures of steps in the program were frequent, participants reported numerous methods of working around these failures so that overall system failure was rare. However, frequent process failure can affect the time required for processing medications, making a system inefficient. This method of interface analysis, called Software Efficiency Evaluation and Fault Identification Method, provides quantitative information with which prototypes can be compared and problems within an interface identified.

Effect of picric acid and enzymatic creatinine on the efficiency of the glomerular filtration rate predicator formula.

PubMed

Qiu, Ling; Guo, Xiuzhi; Zhu, Yan; Shou, Weilin; Gong, Mengchun; Zhang, Lin; Han, Huijuan; Quan, Guoqiang; Xu, Tao; Li, Hang; Li, Xuewang

2013-01-01

To investigate the impact of serum creatinine measurement on the applicability of glomerular filtration rate (GFR) evaluation equations. 99mTc-DTPA plasma clearance rate was used as GFR reference (rGFR) in patients with chronic kidney disease (CKD). Serum creatinine was measureded using enzymatic or picric acid creatinine reagent. The GFR of the patients were estimated using the Cockcroft-Gault equation corrected for body surface area, simplified Modification of Diet in Renal Disease (MDRD) equation, simplified MDRD equation corrected to isotopes dilution mass spectrometry, the CKD epidemiology collaborative research equation, and two Chinese simplified MDRD equations. Significant differences in the eGFR results estimated through enzymatic and picric acid methods were observed for the same evaluation equation. The intraclass correlation coefficient (ICC) of eGFR when the creatinine was measured by the picric acid method was significantly lower than that of the enzymatic method. The assessment accuracy of every equation using the enzymatic method to measure creatinine was significantly higher than that measured by the picric acid method when rGFR was > or = 60 mL/min/1.73m2. A significant difference was demonstrated in the same GFR evaluation equation using the picric acid and enzymatic methods. The enzymatic creatinine method was better than the picric acid method.

Development of the ICD-10 simplified version and field test.

PubMed

Paoin, Wansa; Yuenyongsuwan, Maliwan; Yokobori, Yukiko; Endo, Hiroyoshi; Kim, Sukil

2018-05-01

The International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) has been used in various Asia-Pacific countries for more than 20 years. Although ICD-10 is a powerful tool, clinical coding processes are complex; therefore, many developing countries have not been able to implement ICD-10-based health statistics (WHO-FIC APN, 2007). This study aimed to simplify ICD-10 clinical coding processes, to modify index terms to facilitate computer searching and to provide a simplified version of ICD-10 for use in developing countries. The World Health Organization Family of International Classifications Asia-Pacific Network (APN) developed a simplified version of the ICD-10 and conducted field testing in Cambodia during February and March 2016. Ten hospitals were selected to participate. Each hospital sent a team to join a training workshop before using the ICD-10 simplified version to code 100 cases. All hospitals subsequently sent their coded records to the researchers. Overall, there were 1038 coded records with a total of 1099 ICD clinical codes assigned. The average accuracy rate was calculated as 80.71% (66.67-93.41%). Three types of clinical coding errors were found. These related to errors relating to the coder (14.56%), those resulting from the physician documentation (1.27%) and those considered system errors (3.46%). The field trial results demonstrated that the APN ICD-10 simplified version is feasible for implementation as an effective tool to implement ICD-10 clinical coding for hospitals. Developing countries may consider adopting the APN ICD-10 simplified version for ICD-10 code assignment in hospitals and health care centres. The simplified version can be viewed as an introductory tool which leads to the implementation of the full ICD-10 and may support subsequent ICD-11 adoption.

Analytic model of aurorally coupled magnetospheric and ionospheric electrostatic potentials

NASA Technical Reports Server (NTRS)

Cornwall, J. M.

1994-01-01

This paper describes modest but significant improvements on earlier studies of electrostatic potential structure in the auroral region using the adiabatic auroral arc model. This model has crucial nonlinearities (connected, for example. with aurorally produced ionization) which have hampered analysis; earlier work has either been linear, which I will show is a poor approximation or, if nonlinear, either numerical or too specialized to study parametric dependencies. With certain simplifying assumptions I find new analytic nonlinear solutions fully exhibiting the parametric dependence of potentials on magnetospheric (e.g.. cross-tail potential) and ionospheric (e.g., recombination rate) parameters. No purely phenomenological parameters are introduced. The results are in reasonable agreement with observed average auroral potential drops, inverted-V scale sizes, and dissipation rates. The dissipation rate is quite comparable to tail energization and transport rates and should have a major effect on tail and magnetospheric dynamics. This paper gives various relations between the cross-tail potential and auroral parameters (e.g., total parallel currents and potential drops) which can be studied with existing data sets.

78 FR 41857 - Simplified Cost Accounting and Other Actions To Reduce Paperwork in the Summer Food Service...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-12

... of the number of meals served to eligible children times the operating payment rate. For... meals served to eligible children times the administrative payment rate, or the amount specified in the... maximum ``meals times rates'' combined operating and administrative reimbursement without regard to their...

Impact of Missing Physiologic Data on Performance of the Simplified Acute Physiology Score 3 Risk-Prediction Model.

PubMed

Engerström, Lars; Nolin, Thomas; Mårdh, Caroline; Sjöberg, Folke; Karlström, Göran; Fredrikson, Mats; Walther, Sten M

2017-12-01

The Simplified Acute Physiology 3 outcome prediction model has a narrow time window for recording physiologic measurements. Our objective was to examine the prevalence and impact of missing physiologic data on the Simplified Acute Physiology 3 model's performance. Retrospective analysis of prospectively collected data. Sixty-three ICUs in the Swedish Intensive Care Registry. Patients admitted during 2011-2014 (n = 107,310). None. Model performance was analyzed using the area under the receiver operating curve, scaled Brier's score, and standardized mortality rate. We used a recalibrated Simplified Acute Physiology 3 model and examined model performance in the original dataset and in a dataset of complete records where missing data were generated (simulated dataset). One or more data were missing in 40.9% of the admissions, more common in survivors and low-risk admissions than in nonsurvivors and high-risk admissions. Discrimination did not decrease with one to two missing variables, but accuracy was highest with no missing data. Calibration was best in the original dataset with a mix of full records and records with some missing values (area under the receiver operating curve was 0.85, scaled Brier 27%, and standardized mortality rate 0.99). With zero, one, and two data missing, the scaled Brier was 31%, 26%, and 21%; area under the receiver operating curve was 0.84, 0.87, and 0.89; and standardized mortality rate was 0.92, 1.05 and 1.10, respectively. Datasets where the missing data were simulated for oxygenation or oxygenation and hydrogen ion concentration together performed worse than datasets with these data originally missing. There is a coupling between missing physiologic data, admission type, low risk, and survival. Increased loss of physiologic data reduced model performance and will deflate mortality risk, resulting in falsely high standardized mortality rates.

Quantitative structure-activity relationships for organophosphates binding to acetylcholinesterase.

PubMed

Ruark, Christopher D; Hack, C Eric; Robinson, Peter J; Anderson, Paul E; Gearhart, Jeffery M

2013-02-01

Organophosphates are a group of pesticides and chemical warfare nerve agents that inhibit acetylcholinesterase, the enzyme responsible for hydrolysis of the excitatory neurotransmitter acetylcholine. Numerous structural variants exist for this chemical class, and data regarding their toxicity can be difficult to obtain in a timely fashion. At the same time, their use as pesticides and military weapons is widespread, which presents a major concern and challenge in evaluating human toxicity. To address this concern, a quantitative structure-activity relationship (QSAR) was developed to predict pentavalent organophosphate oxon human acetylcholinesterase bimolecular rate constants. A database of 278 three-dimensional structures and their bimolecular rates was developed from 15 peer-reviewed publications. A database of simplified molecular input line entry notations and their respective acetylcholinesterase bimolecular rate constants are listed in Supplementary Material, Table I. The database was quite diverse, spanning 7 log units of activity. In order to describe their structure, 675 molecular descriptors were calculated using AMPAC 8.0 and CODESSA 2.7.10. Orthogonal projection to latent structures regression, bootstrap leave-random-many-out cross-validation and y-randomization were used to develop an externally validated consensus QSAR model. The domain of applicability was assessed by the William's plot. Six external compounds were outside the warning leverage indicating potential model extrapolation. A number of compounds had residuals >2 or <-2, indicating potential outliers or activity cliffs. The results show that the HOMO-LUMO energy gap contributed most significantly to the binding affinity. A mean training R (2) of 0.80, a mean test set R (2) of 0.76 and a consensus external test set R (2) of 0.66 were achieved using the QSAR. The training and external test set RMSE values were found to be 0.76 and 0.88. The results suggest that this QSAR model can be used in physiologically based pharmacokinetic/pharmacodynamic models of organophosphate toxicity to determine the rate of acetylcholinesterase inhibition.

Preliminary orbit determination for lunar satellites.

NASA Technical Reports Server (NTRS)

Lancaster, E. R.

1973-01-01

Methods for the determination of orbits of artificial lunar satellites from earth-based range rate measurements developed by Koskela (1964) and Bateman et al. (1966) are simplified and extended to include range measurements along with range rate measurements. For illustration, a numerical example is presented.

Theoretical and experimental investigation of architected core materials incorporating negative stiffness elements

NASA Astrophysics Data System (ADS)

Chang, Chia-Ming; Keefe, Andrew; Carter, William B.; Henry, Christopher P.; McKnight, Geoff P.

2014-04-01

Structural assemblies incorporating negative stiffness elements have been shown to provide both tunable damping properties and simultaneous high stiffness and damping over prescribed displacement regions. In this paper we explore the design space for negative stiffness based assemblies using analytical modeling combined with finite element analysis. A simplified spring model demonstrates the effects of element stiffness, geometry, and preloads on the damping and stiffness performance. Simplified analytical models were validated for realistic structural implementations through finite element analysis. A series of complementary experiments was conducted to compare with modeling and determine the effects of each element on the system response. The measured damping performance follows the theoretical predictions obtained by analytical modeling. We applied these concepts to a novel sandwich core structure that exhibited combined stiffness and damping properties 8 times greater than existing foam core technologies.

Working Mechanism for Flexible Perovskite Solar Cells with Simplified Architecture.

PubMed

Xu, Xiaobao; Chen, Qi; Hong, Ziruo; Zhou, Huanping; Liu, Zonghao; Chang, Wei-Hsuan; Sun, Pengyu; Chen, Huajun; De Marco, Nicholas; Wang, Mingkui; Yang, Yang

2015-10-14

In this communication, we report an efficient and flexible perovskite solar cell based on formamidinium lead trihalide (FAPbI3) with simplified configuration. The device achieved a champion efficiency of 12.70%, utilizing direct contact between metallic indium tin oxide (ITO) electrode and perovskite absorber. The underlying working mechanism is proposed subsequently, via a systematic investigation focusing on the heterojunction within this device. A significant charge storage has been observed in the perovskite, which is believed to generate photovoltage and serves as the driving force for charge transferring from the absorber to ITO electrode as well. More importantly, this simplified device structure on flexible substrates suggests its compatibility for scale-up fabrication, which paves the way for commercialization of perovskite photovoltaic technology.

A fluid model simulation of a simplified plasma limiter based on spectral-element time-domain method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Cheng; Ding, Dazhi, E-mail: dzding@njust.edu.cn; Fan, Zhenhong

2015-03-15

A simplified plasma limiter prototype is proposed and the fluid model coupled with Maxwell's equations is established to describe the operating mechanism of plasma limiter. A three-dimensional (3-D) simplified sandwich structure plasma limiter model is analyzed with the spectral-element time-domain (SETD) method. The field breakdown threshold of air and argon at different frequency is predicted and compared with the experimental data and there is a good agreement between them for gas microwave breakdown discharge problems. Numerical results demonstrate that the two-layer plasma limiter (plasma-slab-plasma) has better protective characteristics than a one-layer plasma limiter (slab-plasma-slab) with the same length of gasmore » chamber.« less

Si-Doping Effects in Cu(In,Ga)Se2 Thin Films and Applications for Simplified Structure High-Efficiency Solar Cells.

PubMed

Ishizuka, Shogo; Koida, Takashi; Taguchi, Noboru; Tanaka, Shingo; Fons, Paul; Shibata, Hajime

2017-09-13

We found that elemental Si-doped Cu(In,Ga)Se 2 (CIGS) polycrystalline thin films exhibit a distinctive morphology due to the formation of grain boundary layers several tens of nanometers thick. The use of Si-doped CIGS films as the photoabsorber layer in simplified structure buffer-free solar cell devices is found to be effective in enhancing energy conversion efficiency. The grain boundary layers formed in Si-doped CIGS films are expected to play an important role in passivating CIGS grain interfaces and improving carrier transport. The simplified structure solar cells, which nominally consist of only a CIGS photoabsorber layer and a front transparent and a back metal electrode layer, demonstrate practical application level solar cell efficiencies exceeding 15%. To date, the cell efficiencies demonstrated from this type of device have remained relatively low, with values of about 10%. Also, Si-doped CIGS solar cell devices exhibit similar properties to those of CIGS devices fabricated with post deposition alkali halide treatments such as KF or RbF, techniques known to boost CIGS device performance. The results obtained offer a new approach based on a new concept to control grain boundaries in polycrystalline CIGS and other polycrystalline chalcogenide materials for better device performance.

Simplified three-dimensional model provides anatomical insights in lizards' caudal autotomy as printed illustration.

PubMed

De Amorim, Joana D C G; Travnik, Isadora; De Sousa, Bernadete M

2015-03-01

Lizards' caudal autotomy is a complex and vastly employed antipredator mechanism, with thorough anatomic adaptations involved. Due to its diminished size and intricate structures, vertebral anatomy is hard to be clearly conveyed to students and researchers of other areas. Three-dimensional models are prodigious tools in unveiling anatomical nuances. Some of the techniques used to create them can produce irregular and complicated forms, which despite being very accurate, lack didactical uniformity and simplicity. Since both are considered fundamental characteristics for comprehension, a simplified model could be the key to improve learning. The model here presented depicts the caudal osteology of Tropidurus itambere, and was designed to be concise, in order to be easily assimilated, yet complete, not to compromise the informative aspect. The creation process requires only basic skills in manipulating polygons in 3D modeling softwares, in addition to the appropriate knowledge of the structure to be modeled. As reference for the modeling, we used microscopic observation and a photograph database of the caudal structures. This way, no advanced laboratory equipment was needed and all biological materials were preserved for future research. Therefore, we propose a wider usage of simplified 3D models both in the classroom and as illustrations for scientific publications.

Design and performance evaluation of a simplified dynamic model for combined sewer overflows in pumped sewer systems

NASA Astrophysics Data System (ADS)

van Daal-Rombouts, Petra; Sun, Siao; Langeveld, Jeroen; Bertrand-Krajewski, Jean-Luc; Clemens, François

2016-07-01

Optimisation or real time control (RTC) studies in wastewater systems increasingly require rapid simulations of sewer systems in extensive catchments. To reduce the simulation time calibrated simplified models are applied, with the performance generally based on the goodness of fit of the calibration. In this research the performance of three simplified and a full hydrodynamic (FH) model for two catchments are compared based on the correct determination of CSO event occurrences and of the total discharged volumes to the surface water. Simplified model M1 consists of a rainfall runoff outflow (RRO) model only. M2 combines the RRO model with a static reservoir model for the sewer behaviour. M3 comprises the RRO model and a dynamic reservoir model. The dynamic reservoir characteristics were derived from FH model simulations. It was found that M2 and M3 are able to describe the sewer behaviour of the catchments, contrary to M1. The preferred model structure depends on the quality of the information (geometrical database and monitoring data) available for the design and calibration of the model. Finally, calibrated simplified models are shown to be preferable to uncalibrated FH models when performing optimisation or RTC studies.

Determination of the Shear Stress Distribution in a Laminate from the Applied Shear Resultant--A Simplified Shear Solution

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

2007-01-01

The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate based on laminated beam theory. The method does not consider the solution of a particular boundary value problem, rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

Simplified Models for the Study of Postbuckled Hat-Stiffened Composite Panels

NASA Technical Reports Server (NTRS)

Vescovini, Riccardo; Davila, Carlos G.; Bisagni, Chiara

2012-01-01

The postbuckling response and failure of multistringer stiffened panels is analyzed using models with three levels of approximation. The first model uses a relatively coarse mesh to capture the global postbuckling response of a five-stringer panel. The second model can predict the nonlinear response as well as the debonding and crippling failure mechanisms in a single stringer compression specimen (SSCS). The third model consists of a simplified version of the SSCS that is designed to minimize the computational effort. The simplified model is well-suited to perform sensitivity analyses for studying the phenomena that lead to structural collapse. In particular, the simplified model is used to obtain a deeper understanding of the role played by geometric and material modeling parameters such as mesh size, inter-laminar strength, fracture toughness, and fracture mode mixity. Finally, a global/local damage analysis method is proposed in which a detailed local model is used to scan the global model to identify the locations that are most critical for damage tolerance.

Simplification of irreversible Markov chains by removal of states with fast leaving rates.

PubMed

Jia, Chen

2016-07-07

In the recent work of Ullah et al. (2012a), the authors developed an effective method to simplify reversible Markov chains by removal of states with low equilibrium occupancies. In this paper, we extend this result to irreversible Markov chains. We show that an irreversible chain can be simplified by removal of states with fast leaving rates. Moreover, we reveal that the irreversibility of the chain will always decrease after model simplification. This suggests that although model simplification can retain almost all the dynamic information of the chain, it will lose some thermodynamic information as a trade-off. Examples from biology are also given to illustrate the main results of this paper. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anovulatory and ovulatory infertility: results with simplified management.

PubMed Central

Hull, M G; Savage, P E; Bromham, D R

1982-01-01

A simplified scheme for the management of anovulatory and of ovulatory (usually called unexplained) infertility was evaluated in 244 women. Eighteen patients were excluded because of primary ovarian failure, 164 were treated for ovulatory failure, and 62 with ovulatory infertility remained untreated. Twenty-five patients had a properly validated negative postcoital test. In the remaining 201 patients the two-year conception rates were 96% in patients with amenorrhoea, 83% in those with oligomenorrhoea, 74% in those with luteal deficiency, and 88% in those with ovulatory infertility. Comparison with normal rates implied that amenorrhoea represents a pure form of ovulatory failure that is completely correctable whereas in other conditions unexplained factors also contribute to infertility though to a much smaller extent than was previously thought. PMID:6805656

Delivery of prazosin hydrochloride from osmotic pump system prepared by coating the core tablet with an indentation.

PubMed

Liu, Longxiao; Wang, Jinchao; Zhu, Suyan

2007-04-01

The preparation of an osmotic pump tablet was simplified by elimination of laser drilling using prazosin hydrochloride as the model drug. The osmotic pump system was obtained by coating the indented core tablet compressed by the punch with a needle. A multiple regression equation was achieved with the experimental data of core tablet formulations, and then the formulation was optimized. The influences of the indentation size of the core tablet, environmental media, and agitation rate on drug release profile were investigated. The optimal osmotic pump tablet was found to deliver prazosin hydrochloride at an approximately constant rate up to 24 hr, and independent on both release media and agitation rate. Indentation size of core tablet hardly affected drug release in the range of 0.80-1.15 mm. The method that is simplified by elimination of laser drilling may be promising for preparation of an osmotic pump tablet.

Asymmetry of perceived key movement in chorale sequences: converging evidence from a probe-tone analysis.

PubMed

Cuddy, L L; Thompson, W F

1992-01-01

In a probe-tone experiment, two groups of listeners--one trained, the other untrained, in traditional music theory--rated the goodness of fit of each of the 12 notes of the chromatic scale to four-voice harmonic sequences. Sequences were 12 simplified excerpts from Bach chorales, 4 nonmodulating, and 8 modulating. Modulations occurred either one or two steps in either the clockwise or the counterclockwise direction on the cycle of fifths. A consistent pattern of probe-tone ratings was obtained for each sequence, with no significant differences between listener groups. Two methods of analysis (Fourier analysis and regression analysis) revealed a directional asymmetry in the perceived key movement conveyed by modulating sequences. For a given modulation distance, modulations in the counterclockwise direction effected a clearer shift in tonal organization toward the final key than did clockwise modulations. The nature of the directional asymmetry was consistent with results reported for identification and rating of key change in the sequences (Thompson & Cuddy, 1989a). Further, according to the multiple-regression analysis, probe-tone ratings did not merely reflect the distribution of tones in the sequence. Rather, ratings were sensitive to the temporal structure of the tonal organization in the sequence.

Modeling light and temperature effects on leaf emergence in wheat and barley

NASA Technical Reports Server (NTRS)

Volk, T.; Bugbee, B.

1991-01-01

Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by > 70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than +/- 5% for wheat and less than +/- 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar.

STAT3 Inhibitory Activity of Structurally Simplified Withaferin A Analogues.

PubMed

Tahara, Teruyuki; Streit, Ursula; Pelish, Henry E; Shair, Matthew D

2017-04-07

Signal transducer and activator of transcription 3 (STAT3) is a component of the JAK/STAT pathway. Therapeutic inhibition of STAT3 has been of high interest, as its aberrant activation has been linked to cancer, inflammation, and other human diseases. The withanolide family natural product withaferin A (1) inhibits STAT3 activation. We designed, synthesized, and evaluated simplified withanolide analogues SLW1 (3) and SLW2 (4), and found that SLW1 retained the STAT3 inhibitory activity of withaferin A.

Simplified analysis and optimization of space base and space shuttle heat rejection systems

NASA Technical Reports Server (NTRS)

Wulff, W.

1972-01-01

A simplified radiator system analysis was performed to predict steady state radiator system performance. The system performance was found to be describable in terms of five non-dimensional system parameters. The governing differential equations are integrated numerically to yield the enthalpy rejection for the coolant fluid. The simplified analysis was extended to produce the derivatives of the coolant exit temperature with respect to the governing system parameters. A procedure was developed to find the optimum set of system parameters which yields the lowest possible coolant exit temperature for either a given projected area or a given total mass. The process can be inverted to yield either the minimum area or the minimum mass, together with the optimum geometry, for a specified heat rejection rate.

Influence of model reduction on uncertainty of flood inundation predictions

NASA Astrophysics Data System (ADS)

Romanowicz, R. J.; Kiczko, A.; Osuch, M.

2012-04-01

Derivation of flood risk maps requires an estimation of the maximum inundation extent for a flood with an assumed probability of exceedence, e.g. a 100 or 500 year flood. The results of numerical simulations of flood wave propagation are used to overcome the lack of relevant observations. In practice, deterministic 1-D models are used for flow routing, giving a simplified image of a flood wave propagation process. The solution of a 1-D model depends on the simplifications to the model structure, the initial and boundary conditions and the estimates of model parameters which are usually identified using the inverse problem based on the available noisy observations. Therefore, there is a large uncertainty involved in the derivation of flood risk maps. In this study we examine the influence of model structure simplifications on estimates of flood extent for the urban river reach. As the study area we chose the Warsaw reach of the River Vistula, where nine bridges and several dikes are located. The aim of the study is to examine the influence of water structures on the derived model roughness parameters, with all the bridges and dikes taken into account, with a reduced number and without any water infrastructure. The results indicate that roughness parameter values of a 1-D HEC-RAS model can be adjusted for the reduction in model structure. However, the price we pay is the model robustness. Apart from a relatively simple question regarding reducing model structure, we also try to answer more fundamental questions regarding the relative importance of input, model structure simplification, parametric and rating curve uncertainty to the uncertainty of flood extent estimates. We apply pseudo-Bayesian methods of uncertainty estimation and Global Sensitivity Analysis as the main methodological tools. The results indicate that the uncertainties have a substantial influence on flood risk assessment. In the paper we present a simplified methodology allowing the influence of that uncertainty to be assessed. This work was supported by National Science Centre of Poland (grant 2011/01/B/ST10/06866).

Verification of fluid-structure-interaction algorithms through the method of manufactured solutions for actuator-line applications

NASA Astrophysics Data System (ADS)

Vijayakumar, Ganesh; Sprague, Michael

2017-11-01

Demonstrating expected convergence rates with spatial- and temporal-grid refinement is the ``gold standard'' of code and algorithm verification. However, the lack of analytical solutions and generating manufactured solutions presents challenges for verifying codes for complex systems. The application of the method of manufactured solutions (MMS) for verification for coupled multi-physics phenomena like fluid-structure interaction (FSI) has only seen recent investigation. While many FSI algorithms for aeroelastic phenomena have focused on boundary-resolved CFD simulations, the actuator-line representation of the structure is widely used for FSI simulations in wind-energy research. In this work, we demonstrate the verification of an FSI algorithm using MMS for actuator-line CFD simulations with a simplified structural model. We use a manufactured solution for the fluid velocity field and the displacement of the SMD system. We demonstrate the convergence of both the fluid and structural solver to second-order accuracy with grid and time-step refinement. This work was funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Wind Energy Technologies Office, under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory.

Improved Design of Tunnel Supports : Volume 1 : Simplified Analysis for Ground-Structure Interaction in Tunneling

DOT National Transportation Integrated Search

1980-06-01

The purpose of this report is to provide the tunneling profession with improved practical tools in the technical or design area, which provide more accurate representations of the ground-structure interaction in tunneling. The design methods range fr...

A Simplified Model of Local Structure in Aqueous Proline Amino Acid Revealed by First-Principles Molecular Dynamics Simulations

PubMed Central

Troitzsch, Raphael Z.; Tulip, Paul R.; Crain, Jason; Martyna, Glenn J.

2008-01-01

Aqueous proline solutions are deceptively simple as they can take on complex roles such as protein chaperones, cryoprotectants, and hydrotropic agents in biological processes. Here, a molecular level picture of proline/water mixtures is developed. Car-Parrinello ab initio molecular dynamics (CPAIMD) simulations of aqueous proline amino acid at the B-LYP level of theory, performed using IBM's Blue Gene/L supercomputer and massively parallel software, reveal hydrogen-bonding propensities that are at odds with the predictions of the CHARMM22 empirical force field but are in better agreement with results of recent neutron diffraction experiments. In general, the CPAIMD (B-LYP) simulations predict a simplified structural model of proline/water mixtures consisting of fewer distinct local motifs. Comparisons of simulation results to experiment are made by direct evaluation of the neutron static structure factor S(Q) from CPAIMD (B-LYP) trajectories as well as to the results of the empirical potential structure refinement reverse Monte Carlo procedure applied to the neutron data. PMID:18790850

A simplified model of local structure in aqueous proline amino acid revealed by first-principles molecular dynamics simulations.

PubMed

Troitzsch, Raphael Z; Tulip, Paul R; Crain, Jason; Martyna, Glenn J

2008-12-01

Aqueous proline solutions are deceptively simple as they can take on complex roles such as protein chaperones, cryoprotectants, and hydrotropic agents in biological processes. Here, a molecular level picture of proline/water mixtures is developed. Car-Parrinello ab initio molecular dynamics (CPAIMD) simulations of aqueous proline amino acid at the B-LYP level of theory, performed using IBM's Blue Gene/L supercomputer and massively parallel software, reveal hydrogen-bonding propensities that are at odds with the predictions of the CHARMM22 empirical force field but are in better agreement with results of recent neutron diffraction experiments. In general, the CPAIMD (B-LYP) simulations predict a simplified structural model of proline/water mixtures consisting of fewer distinct local motifs. Comparisons of simulation results to experiment are made by direct evaluation of the neutron static structure factor S(Q) from CPAIMD (B-LYP) trajectories as well as to the results of the empirical potential structure refinement reverse Monte Carlo procedure applied to the neutron data.

Structure and strategy in encoding simplified graphs

NASA Technical Reports Server (NTRS)

Schiano, Diane J.; Tversky, Barbara

1992-01-01

Tversky and Schiano (1989) found a systematic bias toward the 45-deg line in memory for the slopes of identical lines when embedded in graphs, but not in maps, suggesting the use of a cognitive reference frame specifically for encoding meaningful graphs. The present experiments explore this issue further using the linear configurations alone as stimuli. Experiments 1 and 2 demonstrate that perception and immediate memory for the slope of a test line within orthogonal 'axes' are predictable from purely structural considerations. In Experiments 3 and 4, subjects were instructed to use a diagonal-reference strategy in viewing the stimuli, which were described as 'graphs' only in Experiment 3. Results for both studies showed the diagonal bias previously found only for graphs. This pattern provides converging evidence for the diagonal as a cognitive reference frame in encoding linear graphs, and demonstrates that even in highly simplified displays, strategic factors can produce encoding biases not predictable solely from stimulus structure alone.

Simplified DFT methods for consistent structures and energies of large systems

NASA Astrophysics Data System (ADS)

Caldeweyher, Eike; Gerit Brandenburg, Jan

2018-05-01

Kohn–Sham density functional theory (DFT) is routinely used for the fast electronic structure computation of large systems and will most likely continue to be the method of choice for the generation of reliable geometries in the foreseeable future. Here, we present a hierarchy of simplified DFT methods designed for consistent structures and non-covalent interactions of large systems with particular focus on molecular crystals. The covered methods are a minimal basis set Hartree–Fock (HF-3c), a small basis set screened exchange hybrid functional (HSE-3c), and a generalized gradient approximated functional evaluated in a medium-sized basis set (B97-3c), all augmented with semi-classical correction potentials. We give an overview on the methods design, a comprehensive evaluation on established benchmark sets for geometries and lattice energies of molecular crystals, and highlight some realistic applications on large organic crystals with several hundreds of atoms in the primitive unit cell.

Novel Method of Estimating Metabolic Rates of Soldiers Engaged in Chemical Biological Defense Training

DTIC Science & Technology

2016-12-01

Simplified example of estimating metabolic rate from core temperature using the SCENARIO thermoregulatory model. 7 4 Edgewood training site, Day 1, core... temperature (TC) and metabolic rate (Ṁ). 10 5 Edgewood training site, Day 2, core temperature (TC) and metabolic rate (Ṁ). 11 6 Hayward...training site, Day 1, core temperature (TC) and metabolic rate (Ṁ). 12 7 Hayward training site, Day 2, core temperature (TC) and metabolic rate (Ṁ). 13

Computational multiheterodyne spectroscopy

PubMed Central

Burghoff, David; Yang, Yang; Hu, Qing

2016-01-01

Dual-comb spectroscopy allows for high-resolution spectra to be measured over broad bandwidths, but an essential requirement for coherent integration is the availability of a phase reference. Usually, this means that the combs’ phase and timing errors must be measured and either minimized by stabilization or removed by correction, limiting the technique’s applicability. We demonstrate that it is possible to extract the phase and timing signals of a multiheterodyne spectrum completely computationally, without any extra measurements or optical elements. These techniques are viable even when the relative linewidth exceeds the repetition rate difference and can tremendously simplify any dual-comb system. By reconceptualizing frequency combs in terms of the temporal structure of their phase noise, not their frequency stability, we can greatly expand the scope of multiheterodyne techniques. PMID:27847870

Building Roof Segmentation from Aerial Images Using a Line-and Region-Based Watershed Segmentation Technique

PubMed Central

Merabet, Youssef El; Meurie, Cyril; Ruichek, Yassine; Sbihi, Abderrahmane; Touahni, Raja

2015-01-01

In this paper, we present a novel strategy for roof segmentation from aerial images (orthophotoplans) based on the cooperation of edge- and region-based segmentation methods. The proposed strategy is composed of three major steps. The first one, called the pre-processing step, consists of simplifying the acquired image with an appropriate couple of invariant and gradient, optimized for the application, in order to limit illumination changes (shadows, brightness, etc.) affecting the images. The second step is composed of two main parallel treatments: on the one hand, the simplified image is segmented by watershed regions. Even if the first segmentation of this step provides good results in general, the image is often over-segmented. To alleviate this problem, an efficient region merging strategy adapted to the orthophotoplan particularities, with a 2D modeling of roof ridges technique, is applied. On the other hand, the simplified image is segmented by watershed lines. The third step consists of integrating both watershed segmentation strategies into a single cooperative segmentation scheme in order to achieve satisfactory segmentation results. Tests have been performed on orthophotoplans containing 100 roofs with varying complexity, and the results are evaluated with the VINETcriterion using ground-truth image segmentation. A comparison with five popular segmentation techniques of the literature demonstrates the effectiveness and the reliability of the proposed approach. Indeed, we obtain a good segmentation rate of 96% with the proposed method compared to 87.5% with statistical region merging (SRM), 84% with mean shift, 82% with color structure code (CSC), 80% with efficient graph-based segmentation algorithm (EGBIS) and 71% with JSEG. PMID:25648706

Carbon cycling at the tipping point: Does ecosystem structure predict resistance to disturbance?

NASA Astrophysics Data System (ADS)

Gough, C. M.; Bond-Lamberty, B. P.; Stuart-Haentjens, E.; Atkins, J.; Haber, L.; Fahey, R. T.

2017-12-01

Ecosystems worldwide are subjected to disturbances that reshape their physical and biological structure and modify biogeochemical processes, including carbon storage and cycling rates. Disturbances, including those from insect pests, pathogens, and extreme weather, span a continuum of severity and, accordingly, may have different effects on carbon cycling processes. Some ecosystems resist biogeochemical changes following disturbance, until a critical threshold of severity is exceeded. The ecosystem properties underlying such functional resistance, and signifying when a tipping point will occur, however, are almost entirely unknown. Here, we present observational and experimental results from forests in the Great Lakes region, showing ecosystem structure is closely coupled with carbon cycling responses to disturbance, with shifts in structure predicting thresholds of and, in some cases, increases in carbon storage. We find, among forests in the region, that carbon storage regularly exhibits a non-linear threshold response to increasing disturbance levels, but the severity at which a threshold is reached varies among disturbed forests. More biologically and structurally complex forest ecosystems sometimes exhibit greater functional resistance than simpler forests, and consequently may have a higher disturbance severity threshold. Counter to model predictions but consistent with some theoretical frameworks, empirical data show moderate levels of disturbance may increase ecosystem complexity to a point, thereby increasing rates of carbon storage. Disturbances that increase complexity therefore may stimulate carbon storage, while severe disturbances at or beyond thresholds may simplify structure, leading to carbon storage declines. We conclude that ecosystem structural attributes are closely coupled with biogeochemical thresholds across disturbance severity gradients, suggesting that improved predictions of disturbance-related changes in the carbon cycle require better representation of ecosystem structure in models.

78 FR 11988 - Cable Television Act of 1992

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-21

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 76 [MM Docket No. 92-266, FCC 95-397] Cable... Register on October 5, 1995. The Commission simplified rules affecting cable operators' rates and provided cable operators with an additional option for adjusting their rates. DATES: The amendments to 47 CFR 76...

Simplified bridge load rating methodology using the national bridge inventory file : user manual

DOT National Transportation Integrated Search

1988-08-01

The purpose of this research was to develop a computerized system to determine the adequacy of a bridge or group of bridges to carry specified overload vehicles. The system utilizes two levels of analysis. The Level 1 analysis is the basic rating sys...

Simplified bridge load rating methodology using the national bridge inventory file : program listing

DOT National Transportation Integrated Search

1987-08-01

The purpose of this research was to develop a computerized system to determine the adequacy of a bridge or group of bridges to carry specified overload vehicles. The system utilizes two levels of analysis. The Level 1 analysis is the basic rating sys...

Large Angle Transient Dynamics (LATDYN) user's manual

NASA Technical Reports Server (NTRS)

Abrahamson, A. Louis; Chang, Che-Wei; Powell, Michael G.; Wu, Shih-Chin; Bingel, Bradford D.; Theophilos, Paula M.

1991-01-01

A computer code for modeling the large angle transient dynamics (LATDYN) of structures was developed to investigate techniques for analyzing flexible deformation and control/structure interaction problems associated with large angular motions of spacecraft. This type of analysis is beyond the routine capability of conventional analytical tools without simplifying assumptions. In some instances, the motion may be sufficiently slow and the spacecraft (or component) sufficiently rigid to simplify analyses of dynamics and controls by making pseudo-static and/or rigid body assumptions. The LATDYN introduces a new approach to the problem by combining finite element structural analysis, multi-body dynamics, and control system analysis in a single tool. It includes a type of finite element that can deform and rotate through large angles at the same time, and which can be connected to other finite elements either rigidly or through mechanical joints. The LATDYN also provides symbolic capabilities for modeling control systems which are interfaced directly with the finite element structural model. Thus, the nonlinear equations representing the structural model are integrated along with the equations representing sensors, processing, and controls as a coupled system.

Computer program simplifies selection of structural steel columns

NASA Technical Reports Server (NTRS)

Vissing, G. S.

1966-01-01

Computer program rapidly selects appropriate size steel columns and base plates for construction of multistory structures. The program produces a printed record containing the size of a section required at a particular elevation, the stress produced by the loads, and the allowable stresses for that section.

Structurally simplified biphenyl combretastatin A4 derivatives retain in vitro anti-cancer activity dependent on mitotic arrest

PubMed Central

Tarade, Daniel; Ma, Dennis; Pignanelli, Christopher; Mansour, Fadi; Simard, Daniel; van den Berg, Sean; Gauld, James; McNulty, James; Pandey, Siyaram

2017-01-01

The cis-stilbene, combretastatin A4 (CA4), is a potent microtubule targeting and vascular damaging agent. Despite promising results at the pre-clinical level and extensive clinical evaluation, CA4 has yet to be approved for therapeutic use. One impediment to the development of CA4 is an inherent conformational instability about the ethylene linker, which joins two aromatic rings. We have previously published preliminary data regarding structurally simplified biphenyl derivatives of CA4, lacking an ethylene linker, which retain anti-proliferative and pro-apoptotic activity, albeit at higher doses. Our current study provides a more comprehensive evaluation regarding the anti-proliferative and pro-apoptotic properties of biphenyl CA4 derivatives in both 2D and 3D cancerous and non-cancerous cell models. Computational analysis has revealed that cytotoxicity of CA4 and biphenyl analogues correlates with predicted tubulin affinity. Additional mechanistic evaluation of the biphenyl derivatives found that their anti-cancer activity is dependent on prolonged mitotic arrest, in a similar manner to CA4. Lastly, we have shown that cancer cells deficient in the extrinsic pathway of apoptosis experience delayed cell death following treatment with CA4 or analogues. Biphenyl derivatives of CA4 represent structurally simplified analogues of CA4, which retain a similar mechanism of action. The biphenyl analogues warrant in vivo examination to evaluate their potential as vascular damaging agents. PMID:28253265

Application of X-Ray Computer Tomography for Observing the Central Void Formations and the Fuel Pin Deformations of Irradiated FBR Fuel Assemblies

NASA Astrophysics Data System (ADS)

Katsuyama, Kozo; Nagamine, Tsuyoshi; Furuya, Hirotaka

2010-10-01

In order to observe the structural change in the interior of irradiated fuel assemblies, a non-destructive post-irradiation examination (PIE) technique using X-ray computer tomography (X-ray CT) was developed. This X-ray CT technique was applied to observe the central void formations and fuel pin deformations of fuel assemblies which had been irradiated at high linear heat rating. The central void sizes in all fuel pins were measured on five cross sections of the core fuel column as a parameter for evaluating fuel thermal performance. In addition, the fuel pin deformations were analyzed from X-ray CT images obtained along the axial direction of a fuel assembly at the same separation interval. A dependence of void size on the linear heat rating was seen in the fuel assembly irradiated at high linear heat rating. In addition, significant undulations of the fuel pin were observed along the axial direction, coinciding with the wrapping wire pitch in the core fuel column. Application of the developed technique should provide enhanced resolution of measurements and simplify fuel PIEs.

In vitro embryo production in goats: Slaughterhouse and laparoscopic ovum pick up-derived oocytes have different kinetics and requirements regarding maturation media.

PubMed

Souza-Fabjan, Joanna Maria G; Locatelli, Yann; Duffard, Nicolas; Corbin, Emilie; Touzé, Jean-Luc; Perreau, Christine; Beckers, Jean François; Freitas, Vicente José F; Mermillod, Pascal

2014-05-01

A total of 3427 goat oocytes were used in this study to identify possible differences during in vitro embryo production from slaughterhouse or laparoscopic ovum pick up (LOPU) oocytes. In experiment 1, one complex, one semi-defined, and one simplified IVM media were compared using slaughterhouse oocytes. In experiment 2, we checked the effect of oocyte origin (slaughterhouse or LOPU) on the kinetics of maturation (18 vs. 22 vs. 26 hours) when submitted to semi-defined or simplified media. In experiment 3, we determined the differences in embryo development between slaughterhouse and LOPU oocytes when submitted to both media and then to IVF or parthenogenetic activation (PA). Embryos from all groups were vitrified, and their viability evaluated in vitro after thawing. In experiment 1, no difference (P > 0.05) was detected among treatments for maturation rate (metaphase II [MII]; 88% on average), cleavage (72%), blastocyst from the initial number of cumulus oocyte complexes (46%) or from the cleaved ones (63%), hatching rate (69%), and the total number of blastomeres (187). In experiment 2, there was no difference of MII rate between slaughterhouse oocytes cultured for 18 or 22 hours, whereas the MII rate increased significantly (P < 0.05) between 18 and 22 hours for LOPU oocytes in the simplified medium. Moreover, slaughterhouse oocytes cultured in simplified medium matured significantly faster than LOPU oocytes at 18 and 22 hours (P < 0.05). In experiment 3, cleavage rate was significantly greater (P < 0.001) in all four groups of embryos produced by PA than IVF. Interestingly, PA reached similar rates for slaughterhouse oocytes cultured in both media, but improved (P < 0.05) the cleavage rate of LOPU oocytes. Slaughterhouse oocytes had acceptable cleavage rate after IVF (∼67%), whereas LOPU oocytes displayed a lower one (∼38%), in contrast to cleavage after PA. The percentage of blastocysts in relation to cleaved embryos was not affected by the origin of the oocytes (P > 0.05). Therefore, slaughterhouse oocytes developed a greater proportion of blastocysts than LOPU ones, expressed as the percentage of total cumulus oocyte complexes entering to IVM. Vitrified-thawed blastocysts presented similar survival and hatching rates between the oocyte origin, media, or method of activation. In conclusion, slaughterhouse and LOPU derived oocytes may have different IVM kinetics and require different IVM and IVF conditions. Although the IVM and IVF systems still need improvements to enhance embryo yield, the in vitro development step is able to generate good quality embryos from LOPU-derived oocytes. Copyright © 2014 Elsevier Inc. All rights reserved.

The role of interest and inflation rates in life-cycle cost analysis

NASA Technical Reports Server (NTRS)

Eisenberger, I.; Remer, D. S.; Lorden, G.

1978-01-01

The effect of projected interest and inflation rates on life cycle cost calculations is discussed and a method is proposed for making such calculations which replaces these rates by a single parameter. Besides simplifying the analysis, the method clarifies the roles of these rates. An analysis of historical interest and inflation rates from 1950 to 1976 shows that the proposed method can be expected to yield very good projections of life cycle cost even if the rates themselves fluctuate considerably.

W-algebra for solving problems with fuzzy parameters

NASA Astrophysics Data System (ADS)

Shevlyakov, A. O.; Matveev, M. G.

2018-03-01

A method of solving the problems with fuzzy parameters by means of a special algebraic structure is proposed. The structure defines its operations through operations on real numbers, which simplifies its use. It avoids deficiencies limiting applicability of the other known structures. Examples for solution of a quadratic equation, a system of linear equations and a network planning problem are given.

Linking dynamics of the inhibitory network to the input structure

PubMed Central

Komarov, Maxim

2017-01-01

Networks of inhibitory interneurons are found in many distinct classes of biological systems. Inhibitory interneurons govern the dynamics of principal cells and are likely to be critically involved in the coding of information. In this theoretical study, we describe the dynamics of a generic inhibitory network in terms of low-dimensional, simplified rate models. We study the relationship between the structure of external input applied to the network and the patterns of activity arising in response to that stimulation. We found that even a minimal inhibitory network can generate a great diversity of spatio-temporal patterning including complex bursting regimes with non-trivial ratios of burst firing. Despite the complexity of these dynamics, the network’s response patterns can be predicted from the rankings of the magnitudes of external inputs to the inhibitory neurons. This type of invariant dynamics is robust to noise and stable in densely connected networks with strong inhibitory coupling. Our study predicts that the response dynamics generated by an inhibitory network may provide critical insights about the temporal structure of the sensory input it receives. PMID:27650865

Toward a better understanding of helicopter stability derivatives

NASA Technical Reports Server (NTRS)

Hansen, R. S.

1982-01-01

An amended six degree of freedom helicopter stability and control derivative model was developed in which body acceleration and control rate derivatives were included in the Taylor series expansion. These additional derivatives were derived from consideration of the effects of the higher order rotor flapping dynamics, which are known to be inadequately represented in the conventional six degree of freedom, quasistatic stability derivative model. The amended model was a substantial improvement over the conventional model, effectively doubling the unsable bandwidth and providing a more accurate representation of the short period and cross axis characteristics. Further investigations assessed the applicability of the two stability derivative model structures for flight test parameter identification. Parameters were identified using simulation data generated from a higher order base line model having sixth order rotor tip path plane dynamics. Three lower order models were identified: one using the conventional stability derivative model structure, a second using the amended six degree of freedom model structure, and a third model having eight degrees of freedom that included a simplified rotor tip path plane tilt representation.

Design of a sensor network for structural health monitoring of a full-scale composite horizontal tail

NASA Astrophysics Data System (ADS)

Gao, Dongyue; Wang, Yishou; Wu, Zhanjun; Rahim, Gorgin; Bai, Shengbao

2014-05-01

The detection capability of a given structural health monitoring (SHM) system strongly depends on its sensor network placement. In order to minimize the number of sensors while maximizing the detection capability, optimal design of the PZT sensor network placement is necessary for structural health monitoring (SHM) of a full-scale composite horizontal tail. In this study, the sensor network optimization was simplified as a problem of determining the sensor array placement between stiffeners to achieve the desired the coverage rate. First, an analysis of the structural layout and load distribution of a composite horizontal tail was performed. The constraint conditions of the optimal design were presented. Then, the SHM algorithm of the composite horizontal tail under static load was proposed. Based on the given SHM algorithm, a sensor network was designed for the full-scale composite horizontal tail structure. Effective profiles of cross-stiffener paths (CRPs) and uncross-stiffener paths (URPs) were estimated by a Lamb wave propagation experiment in a multi-stiffener composite specimen. Based on the coverage rate and the redundancy requirements, a seven-sensor array-network was chosen as the optimal sensor network for each airfoil. Finally, a preliminary SHM experiment was performed on a typical composite aircraft structure component. The reliability of the SHM result for a composite horizontal tail structure under static load was validated. In the result, the red zone represented the delamination damage. The detection capability of the optimized sensor network was verified by SHM of a full-scale composite horizontal tail; all the diagnosis results were obtained in two minutes. The result showed that all the damage in the monitoring region was covered by the sensor network.

Assessing uncertainty in radar measurements on simplified meteorological scenarios

NASA Astrophysics Data System (ADS)

Molini, L.; Parodi, A.; Rebora, N.; Siccardi, F.

2006-02-01

A three-dimensional radar simulator model (RSM) developed by Haase (1998) is coupled with the nonhydrostatic mesoscale weather forecast model Lokal-Modell (LM). The radar simulator is able to model reflectivity measurements by using the following meteorological fields, generated by Lokal Modell, as inputs: temperature, pressure, water vapour content, cloud water content, cloud ice content, rain sedimentation flux and snow sedimentation flux. This work focuses on the assessment of some uncertainty sources associated with radar measurements: absorption by the atmospheric gases, e.g., molecular oxygen, water vapour, and nitrogen; attenuation due to the presence of a highly reflecting structure between the radar and a "target structure". RSM results for a simplified meteorological scenario, consisting of a humid updraft on a flat surface and four cells placed around it, are presented.

Simplified Model to Predict Deflection and Natural Frequency of Steel Pole Structures

NASA Astrophysics Data System (ADS)

Balagopal, R.; Prasad Rao, N.; Rokade, R. P.

2018-04-01

Steel pole structures are suitable alternate to transmission line towers, due to difficulty encountered in finding land for the new right of way for installation of new lattice towers. The steel poles have tapered cross section and they are generally used for communication, power transmission and lighting purposes. Determination of deflection of steel pole is important to decide its functionality requirement. The excessive deflection of pole may affect the signal attenuation and short circuiting problems in communication/transmission poles. In this paper, a simplified method is proposed to determine both primary and secondary deflection based on dummy unit load/moment method. The predicted deflection from proposed method is validated with full scale experimental investigation conducted on 8 m and 30 m high lighting mast, 132 and 400 kV transmission pole and found to be in close agreement with each other. Determination of natural frequency is an important criterion to examine its dynamic sensitivity. A simplified semi-empirical method using the static deflection from the proposed method is formulated to determine its natural frequency. The natural frequency predicted from proposed method is validated with FE analysis results. Further the predicted results are validated with experimental results available in literature.

A pediatric brain structure atlas from T1-weighted MR images

NASA Astrophysics Data System (ADS)

Shan, Zuyao Y.; Parra, Carlos; Ji, Qing; Ogg, Robert J.; Zhang, Yong; Laningham, Fred H.; Reddick, Wilburn E.

2006-03-01

In this paper, we have developed a digital atlas of the pediatric human brain. Human brain atlases, used to visualize spatially complex structures of the brain, are indispensable tools in model-based segmentation and quantitative analysis of brain structures. However, adult brain atlases do not adequately represent the normal maturational patterns of the pediatric brain, and the use of an adult model in pediatric studies may introduce substantial bias. Therefore, we proposed to develop a digital atlas of the pediatric human brain in this study. The atlas was constructed from T1 weighted MR data set of a 9 year old, right-handed girl. Furthermore, we extracted and simplified boundary surfaces of 25 manually defined brain structures (cortical and subcortical) based on surface curvature. Higher curvature surfaces were simplified with more reference points; lower curvature surfaces, with fewer. We constructed a 3D triangular mesh model for each structure by triangulation of the structure's reference points. Kappa statistics (cortical, 0.97; subcortical, 0.91) indicated substantial similarities between the mesh-defined and the original volumes. Our brain atlas and structural mesh models (www.stjude.org/BrainAtlas) can be used to plan treatment, to conduct knowledge and modeldriven segmentation, and to analyze the shapes of brain structures in pediatric patients.

Estimation of cardiac reserve by peak power: validation and initial application of a simplified index

NASA Technical Reports Server (NTRS)

Armstrong, G. P.; Carlier, S. G.; Fukamachi, K.; Thomas, J. D.; Marwick, T. H.

1999-01-01

OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection fraction or rate-pressure product.

Kinematic equations for resolved-rate control of an industrial robot arm

NASA Technical Reports Server (NTRS)

Barker, L. K.

1983-01-01

An operator can use kinematic, resolved-rate equations to dynamically control a robot arm by watching its response to commanded inputs. Known resolved-rate equations for the control of a particular six-degree-of-freedom industrial robot arm and proceeds to simplify the equations for faster computations are derived. Methods for controlling the robot arm in regions which normally cause mathematical singularities in the resolved-rate equations are discussed.

Non-homogeneous hybrid rocket fuel for enhanced regression rates utilizing partial entrainment

NASA Astrophysics Data System (ADS)

Boronowsky, Kenny

A concept was developed and tested to enhance the performance and regression rate of hydroxyl terminated polybutadiene (HTPB), a commonly used hybrid rocket fuel. By adding small nodules of paraffin into the HTPB fuel, a non-homogeneous mixture was created resulting in increased regression rates. The goal was to develop a fuel with a simplified single core geometry and a tailorable regression rate. The new fuel would benefit from the structural stability of HTPB yet not suffer from the large void fraction representative of typical HTPB core geometries. Regression rates were compared between traditional HTPB single core grains, 85% HTPB mixed with 15% (by weight) paraffin cores, 70% HTPB mixed with 30% paraffin cores, and plain paraffin single core grains. Each fuel combination was tested at oxidizer flow rates, ranging from 0.9 - 3.3 g/s of gaseous oxygen, in a small scale hybrid test rocket and average regression rates were measured. While large uncertainties were present in the experimental setup, the overall data showed that the regression rate was enhanced as paraffin concentration increased. While further testing would be required at larger scales of interest, the trends are encouraging. Inclusion of paraffin nodules in the HTPB grain may produce a greater advantage than other more noxious additives in current use. In addition, it may lead to safer rocket motors with higher integrated thrust due to the decreased void fraction.

A Z-Axis Quartz Cross-Fork Micromachined Gyroscope Based on Shear Stress Detection

PubMed Central

Xie, Liqiang; Wu, Xuezhong; Li, Shengyi; Wang, Haoxu; Su, Jianbin; Dong, Peitao

2010-01-01

Here we propose a novel quartz micromachined gyroscope. The sensor has a simple cross-fork structure in the x-y plane of quartz crystal. Shear stress rather than normal stress is utilized to sense Coriolis’ force generated by the input angular rate signal. Compared to traditional quartz gyroscopes, which have two separate sense electrodes on each sidewall, there is only one electrode on each sidewall of the sense beam. As a result, the fabrication of the electrodes is simplified and the structure can be easily miniaturized. In order to increase sensitivity, a pair of proof masses is attached to the ends of the drive beam, and the sense beam has a tapered design. The structure is etched from a z-cut quartz wafer and the electrodes are realized by direct evaporation using the aperture mask method. The drive mode frequency of the prototype is 13.38 kHz, and the quality factor is approximately 1,000 in air. Therefore, the gyroscope can work properly without a vacuum package. The measurement ability of the shear stress detection design scheme is validated by the Coriolis’ force test. The performance of the sensor is characterized on a precision rate table using a specially designed readout circuit. The experimentally obtained scale factor is 1.45 mV/°/s and the nonlinearity is 3.6% in range of ±200 °/s. PMID:22294887

Use of Savitzky-Golay Filter for Performances Improvement of SHM Systems Based on Neural Networks and Distributed PZT Sensors.

PubMed

de Oliveira, Mario A; Araujo, Nelcileno V S; da Silva, Rodolfo N; da Silva, Tony I; Epaarachchi, Jayantha

2018-01-08

A considerable amount of research has focused on monitoring structural damage using Structural Health Monitoring (SHM) technologies, which has had recent advances. However, it is important to note the challenges and unresolved problems that disqualify currently developed monitoring systems. One of the frontline SHM technologies, the Electromechanical Impedance (EMI) technique, has shown its potential to overcome remaining problems and challenges. Unfortunately, the recently developed neural network algorithms have not shown significant improvements in the accuracy of rate and the required processing time. In order to fill this gap in advanced neural networks used with EMI techniques, this paper proposes an enhanced and reliable strategy for improving the structural damage detection via: (1) Savitzky-Golay (SG) filter, using both first and second derivatives; (2) Probabilistic Neural Network (PNN); and, (3) Simplified Fuzzy ARTMAP Network (SFAN). Those three methods were employed to analyze the EMI data experimentally obtained from an aluminum plate containing three attached PZT (Lead Zirconate Titanate) patches. In this present study, the damage scenarios were simulated by attaching a small metallic nut at three different positions in the aluminum plate. We found that the proposed method achieves a hit rate of more than 83%, which is significantly higher than current state-of-the-art approaches. Furthermore, this approach results in an improvement of 93% when considering the best case scenario.

Use of Savitzky–Golay Filter for Performances Improvement of SHM Systems Based on Neural Networks and Distributed PZT Sensors

PubMed Central

Araujo, Nelcileno V. S.; da Silva, Rodolfo N.; da Silva, Tony I.; Epaarachchi, Jayantha

2018-01-01

A considerable amount of research has focused on monitoring structural damage using Structural Health Monitoring (SHM) technologies, which has had recent advances. However, it is important to note the challenges and unresolved problems that disqualify currently developed monitoring systems. One of the frontline SHM technologies, the Electromechanical Impedance (EMI) technique, has shown its potential to overcome remaining problems and challenges. Unfortunately, the recently developed neural network algorithms have not shown significant improvements in the accuracy of rate and the required processing time. In order to fill this gap in advanced neural networks used with EMI techniques, this paper proposes an enhanced and reliable strategy for improving the structural damage detection via: (1) Savitzky–Golay (SG) filter, using both first and second derivatives; (2) Probabilistic Neural Network (PNN); and, (3) Simplified Fuzzy ARTMAP Network (SFAN). Those three methods were employed to analyze the EMI data experimentally obtained from an aluminum plate containing three attached PZT (Lead Zirconate Titanate) patches. In this present study, the damage scenarios were simulated by attaching a small metallic nut at three different positions in the aluminum plate. We found that the proposed method achieves a hit rate of more than 83%, which is significantly higher than current state-of-the-art approaches. Furthermore, this approach results in an improvement of 93% when considering the best case scenario. PMID:29316693

A mathematical model captures the structure of subjective affect

PubMed Central

Mattek, Alison M.; Wolford, George; Whalen, Paul J.

2016-01-01

While it is possible to observe when another person is having an emotional moment, we also derive information about the affective states of others from what they tell us they are feeling. In an effort to distill the complexity of affective experience, psychologists routinely focus on a simplified subset of subjective rating scales (i.e., dimensions) that capture considerable variability in reported affect: reported valence (i.e., how good or bad?) and reported arousal (e.g., how strong is the emotion you are feeling?). Still, existing theoretical approaches address the basic organization and measurement of these affective dimensions differently. Some approaches organize affect around the dimensions of bipolar valence and arousal (e.g., the circumplex model; Russell, 1980), whereas alternative approaches organize affect around the dimensions of unipolar positivity and unipolar negativity (e.g., the bivariate evaluative model; Cacioppo & Berntson, 1994). In this report, we (1) replicate the data structure observed when collected according to the two approaches described above, and re-interpret these data to suggest that the relationship between each pair of affective dimensions is conditional on valence ambiguity; then (2) formalize this structure with a mathematical model depicting a valence ambiguity dimension that decreases in range as arousal decreases (a triangle). This model captures variability in affective ratings better than alternative approaches, increasing variance explained from ~60% to over 90% without adding parameters. PMID:28544868

Sound production due to large-scale coherent structures

NASA Technical Reports Server (NTRS)

Gatski, T. B.

1979-01-01

The acoustic pressure fluctuations due to large-scale finite amplitude disturbances in a free turbulent shear flow are calculated. The flow is decomposed into three component scales; the mean motion, the large-scale wave-like disturbance, and the small-scale random turbulence. The effect of the large-scale structure on the flow is isolated by applying both a spatial and phase average on the governing differential equations and by initially taking the small-scale turbulence to be in energetic equilibrium with the mean flow. The subsequent temporal evolution of the flow is computed from global energetic rate equations for the different component scales. Lighthill's theory is then applied to the region with the flowfield as the source and an observer located outside the flowfield in a region of uniform velocity. Since the time history of all flow variables is known, a minimum of simplifying assumptions for the Lighthill stress tensor is required, including no far-field approximations. A phase average is used to isolate the pressure fluctuations due to the large-scale structure, and also to isolate the dynamic process responsible. Variation of mean square pressure with distance from the source is computed to determine the acoustic far-field location and decay rate, and, in addition, spectra at various acoustic field locations are computed and analyzed. Also included are the effects of varying the growth and decay of the large-scale disturbance on the sound produced.

The influence of computational assumptions on analysing abdominal aortic aneurysm haemodynamics.

PubMed

Ene, Florentina; Delassus, Patrick; Morris, Liam

2014-08-01

The variation in computational assumptions for analysing abdominal aortic aneurysm haemodynamics can influence the desired output results and computational cost. Such assumptions for abdominal aortic aneurysm modelling include static/transient pressures, steady/transient flows and rigid/compliant walls. Six computational methods and these various assumptions were simulated and compared within a realistic abdominal aortic aneurysm model with and without intraluminal thrombus. A full transient fluid-structure interaction was required to analyse the flow patterns within the compliant abdominal aortic aneurysms models. Rigid wall computational fluid dynamics overestimates the velocity magnitude by as much as 40%-65% and the wall shear stress by 30%-50%. These differences were attributed to the deforming walls which reduced the outlet volumetric flow rate for the transient fluid-structure interaction during the majority of the systolic phase. Static finite element analysis accurately approximates the deformations and von Mises stresses when compared with transient fluid-structure interaction. Simplifying the modelling complexity reduces the computational cost significantly. In conclusion, the deformation and von Mises stress can be approximately found by static finite element analysis, while for compliant models a full transient fluid-structure interaction analysis is required for acquiring the fluid flow phenomenon. © IMechE 2014.

A simplified CT-guided approach for greater occipital nerve infiltration in the management of occipital neuralgia.

PubMed

Kastler, Adrian; Onana, Yannick; Comte, Alexandre; Attyé, Arnaud; Lajoie, Jean-Louis; Kastler, Bruno

2015-08-01

To evaluate the efficacy of a simplified CT-guided greater occipital nerve (GON) infiltration approach in the management of occipital neuralgia (ON). Local IRB approval was obtained and written informed consent was waived. Thirty three patients suffering from severe refractory ON who underwent a total of 37 CT-guided GON infiltrations were included between 2012 and 2014. GON infiltration was performed at the first bend of the GON, between the inferior obliqus capitis and semispinalis capitis muscles with local anaesthetics and cortivazol. Pain was evaluated via VAS scores. Clinical success was defined by pain relief greater than or equal to 50 % lasting for at least 3 months. The pre-procedure mean pain score was 8/10. Patients suffered from left GON neuralgia in 13 cases, right GON neuralgia in 16 cases and bilateral GON neuralgia in 4 cases. The clinical success rate was 86 %. In case of clinical success, the mean pain relief duration following the procedure was 9.16 months. Simplified CT-guided infiltration appears to be effective in managing refractory ON. With this technique, infiltration of the GON appears to be faster, technically easier and, therefore, safer compared with other previously described techniques. • Occipital neuralgia is a very painful and debilitating condition • GON infiltrations have been successful in the treatment of occipital neuralgia • This simplified technique presents a high efficacy rate with long-lasting pain relief • This infiltration technique does not require contrast media injection for pre-planning • GON infiltration at the first bend appears easier and safer.

Comparative efficacy of a simplified handwashing program for improvement in hand hygiene and reduction of school absenteeism among children with intellectual disability.

PubMed

Lee, Regina L T; Leung, Cynthia; Tong, Wah Kun; Chen, Hong; Lee, Paul H

2015-09-01

Infectious diseases are common among schoolchildren as a result of their poor hand hygiene, especially in those who have developmental disabilities. A quasi-experimental study using a pre- to post-test design with a control group was used to test the feasibility and sustainability of simplified 5-step handwashing techniques to measure the hand hygiene outcome for students with mild intellectual disability. Sickness-related school absenteeism was compared. The intervention group experienced a significant increase in the rating of their handwashing quality in both hands from pre- to post-test: left dorsum (+1.05, P < .001); right dorsum (+1.00, P < .001); left palm (+0.98, P < .001); and right palm (+1.09, P < .001). The pre- to post-test difference in the intervention group (+1.03, P < .001) was significantly greater than the difference in the control group (+0.34, P = .001). There were no differences between the post-test and the sustainability assessment in the intervention group. The intervention school experienced a significantly lower absenteeism rate (0.0167) than the control group in the same year (0.028, P = .04).Students in this study showed better performance in simplified handwashing techniques and experienced lower absenteeism than those using usual practice in special education school settings. The simplified 5-step hand hygiene technique has been proven effective in reducing the spread of infectious diseases. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Control pole placement relationships

NASA Technical Reports Server (NTRS)

Ainsworth, O. R.

1982-01-01

Using a simplified Large Space Structure (LSS) model, a technique was developed which gives algebraic relationships for the unconstrained poles. The relationships, which were obtained by this technique, are functions of the structural characteristics and the control gains. Extremely interesting relationships evolve for the case when the structural damping is zero. If the damping is zero, the constrained poles are uncoupled from the structural mode shapes. These relationships, which are derived for structural damping and without structural damping, provide new insight into the migration of the unconstrained poles for the CFPPS.

Linear network representation of multistate models of transport.

PubMed Central

Sandblom, J; Ring, A; Eisenman, G

1982-01-01

By introducing external driving forces in rate-theory models of transport we show how the Eyring rate equations can be transformed into Ohm's law with potentials that obey Kirchhoff's second law. From such a formalism the state diagram of a multioccupancy multicomponent system can be directly converted into linear network with resistors connecting nodal (branch) points and with capacitances connecting each nodal point with a reference point. The external forces appear as emf or current generators in the network. This theory allows the algebraic methods of linear network theory to be used in solving the flux equations for multistate models and is particularly useful for making proper simplifying approximation in models of complex membrane structure. Some general properties of linear network representation are also deduced. It is shown, for instance, that Maxwell's reciprocity relationships of linear networks lead directly to Onsager's relationships in the near equilibrium region. Finally, as an example of the procedure, the equivalent circuit method is used to solve the equations for a few transport models. PMID:7093425

On the spin-axis dynamics of a Moonless Earth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Gongjie; Batygin, Konstantin, E-mail: gli@cfa.harvard.edu

2014-07-20

The variation of a planet's obliquity is influenced by the existence of satellites with a high mass ratio. For instance, Earth's obliquity is stabilized by the Moon and would undergo chaotic variations in the Moon's absence. In turn, such variations can lead to large-scale changes in the atmospheric circulation, rendering spin-axis dynamics a central issue for understanding climate. The relevant quantity for dynamically forced climate change is the rate of chaotic diffusion. Accordingly, here we re-examine the spin-axis evolution of a Moonless Earth within the context of a simplified perturbative framework. We present analytical estimates of the characteristic Lyapunov coefficientmore » as well as the chaotic diffusion rate and demonstrate that even in absence of the Moon, the stochastic change in Earth's obliquity is sufficiently slow to not preclude long-term habitability. Our calculations are consistent with published numerical experiments and illustrate the putative system's underlying dynamical structure in a simple and intuitive manner.« less

On the combinatorics of sparsification.

PubMed

Huang, Fenix Wd; Reidys, Christian M

2012-10-22

We study the sparsification of dynamic programming based on folding algorithms of RNA structures. Sparsification is a method that improves significantly the computation of minimum free energy (mfe) RNA structures. We provide a quantitative analysis of the sparsification of a particular decomposition rule, Λ∗. This rule splits an interval of RNA secondary and pseudoknot structures of fixed topological genus. Key for quantifying sparsifications is the size of the so called candidate sets. Here we assume mfe-structures to be specifically distributed (see Assumption 1) within arbitrary and irreducible RNA secondary and pseudoknot structures of fixed topological genus. We then present a combinatorial framework which allows by means of probabilities of irreducible sub-structures to obtain the expectation of the Λ∗-candidate set w.r.t. a uniformly random input sequence. We compute these expectations for arc-based energy models via energy-filtered generating functions (GF) in case of RNA secondary structures as well as RNA pseudoknot structures. Furthermore, for RNA secondary structures we also analyze a simplified loop-based energy model. Our combinatorial analysis is then compared to the expected number of Λ∗-candidates obtained from the folding mfe-structures. In case of the mfe-folding of RNA secondary structures with a simplified loop-based energy model our results imply that sparsification provides a significant, constant improvement of 91% (theory) to be compared to an 96% (experimental, simplified arc-based model) reduction. However, we do not observe a linear factor improvement. Finally, in case of the "full" loop-energy model we can report a reduction of 98% (experiment). Sparsification was initially attributed a linear factor improvement. This conclusion was based on the so called polymer-zeta property, which stems from interpreting polymer chains as self-avoiding walks. Subsequent findings however reveal that the O(n) improvement is not correct. The combinatorial analysis presented here shows that, assuming a specific distribution (see Assumption 1), of mfe-structures within irreducible and arbitrary structures, the expected number of Λ∗-candidates is Θ(n2). However, the constant reduction is quite significant, being in the range of 96%. We furthermore show an analogous result for the sparsification of the Λ∗-decomposition rule for RNA pseudoknotted structures of genus one. Finally we observe that the effect of sparsification is sensitive to the employed energy model.

Sintering Process and Mechanical Property of MWCNTs/HDPE Bulk Composite.

PubMed

Ming-Wen, Wang; Tze-Chi, Hsu; Jie-Ren, Zheng

2009-08-01

Studies have proved that increasing polymer matrices by carbon nanotubes to form structural reinforcement and electrical conductivity have significantly improved mechanical and electrical properties at very low carbon nanotubes loading. In other words, increasing polymer matrices by carbon nanotubes to form structural reinforcement can reduce friction coefficient and enhance anti-wear property. However, producing traditional MWCNTs in polymeric materix is an extremely complicated process. Using melt-mixing process or in situ polymerization leads to better dispersion effect on composite materials. In this study, therefore, to simplify MWCNTs /HDPE composite process and increase dispersion, powder was used directly to replace pellet to mix and sinter with MWCNTs. The composite bulks with 0, 0.5, 1, 2 and 4% nanotube content by weight was analyzed under SEM to observe nanotubes dispersion. At this rate, a MWCNTs/HDPE composite bulk with uniformly dispersed MWCNTs was achieved, and through the wear bench (Pin-on-Disk), the wear experiment has accomplished. Accordingly, the result suggests the sintered MWCNTs/HDPE composites amplify the hardness and wear-resist property.

CO2 Biofixation and Growth Kinetics of Chlorella vulgaris and Nannochloropsis gaditana.

PubMed

Adamczyk, Michał; Lasek, Janusz; Skawińska, Agnieszka

2016-08-01

CO2 biofixation was investigated using tubular bioreactors (15 and 1.5 l) either in the presence of green algae Chlorella vulgaris or Nannochloropsis gaditana. The cultivation was carried out in the following conditions: temperature of 25 °C, inlet-CO2 of 4 and 8 vol%, and artificial light enhancing photosynthesis. Higher biofixation were observed in 8 vol% CO2 concentration for both microalgae cultures than in 4 vol%. Characteristic process parameters such as productivity, CO2 fixation, and kinetic rate coefficient were determined and discussed. Simplified and advanced methods for determination of CO2 fixation were compared. In a simplified method, it is assumed that 1 kg of produced biomass equals 1.88 kg recycled CO2. Advance method is based on empirical results of the present study (formula with carbon content in biomass). It was observed that application of the simplified method can generate large errors, especially if the biomass contains a relatively low amount of carbon. N. gaditana is the recommended species for CO2 removal due to a high biofixation rate-more than 1.7 g/l/day. On day 10 of cultivation, the cell concentration was more than 1.7 × 10(7) cells/ml. In the case of C. vulgaris, the maximal biofixation rate and cell concentration did not exceed 1.4 g/l/day and 1.3 × 10(7) cells/ml, respectively.

A transfer function type of simplified electrochemical model with modified boundary conditions and Padé approximation for Li-ion battery: Part 1. lithium concentration estimation

NASA Astrophysics Data System (ADS)

Yuan, Shifei; Jiang, Lei; Yin, Chengliang; Wu, Hongjie; Zhang, Xi

2017-06-01

To guarantee the safety, high efficiency and long lifetime for lithium-ion battery, an advanced battery management system requires a physics-meaningful yet computationally efficient battery model. The pseudo-two dimensional (P2D) electrochemical model can provide physical information about the lithium concentration and potential distributions across the cell dimension. However, the extensive computation burden caused by the temporal and spatial discretization limits its real-time application. In this research, we propose a new simplified electrochemical model (SEM) by modifying the boundary conditions for electrolyte diffusion equations, which significantly facilitates the analytical solving process. Then to obtain a reduced order transfer function, the Padé approximation method is adopted to simplify the derived transcendental impedance solution. The proposed model with the reduced order transfer function can be briefly computable and preserve physical meanings through the presence of parameters such as the solid/electrolyte diffusion coefficients (Ds&De) and particle radius. The simulation illustrates that the proposed simplified model maintains high accuracy for electrolyte phase concentration (Ce) predictions, saying 0.8% and 0.24% modeling error respectively, when compared to the rigorous model under 1C-rate pulse charge/discharge and urban dynamometer driving schedule (UDDS) profiles. Meanwhile, this simplified model yields significantly reduced computational burden, which benefits its real-time application.

An Ecological Context for Regenerating Mult-cohort, Mixed-species Red Pine Forests

Treesearch

Brian Palik; John Zasada

2003-01-01

Human disturbances have simplified the structure and composition of red pine forest, relative to historical conditions. A greater understanding of natureal disturbances and their role in generating complex stand structures, and their associated benefits, has increased interest in managing for mixed-species, multi-aged stands. We outline a conceptual approach for...

Further Simplification of the Simple Erosion Narrowing Score With Item Response Theory Methodology.

PubMed

Oude Voshaar, Martijn A H; Schenk, Olga; Ten Klooster, Peter M; Vonkeman, Harald E; Bernelot Moens, Hein J; Boers, Maarten; van de Laar, Mart A F J

2016-08-01

To further simplify the simple erosion narrowing score (SENS) by removing scored areas that contribute the least to its measurement precision according to analysis based on item response theory (IRT) and to compare the measurement performance of the simplified version to the original. Baseline and 18-month data of the Combinatietherapie Bij Reumatoide Artritis (COBRA) trial were modeled using longitudinal IRT methodology. Measurement precision was evaluated across different levels of structural damage. SENS was further simplified by omitting the least reliably scored areas. Discriminant validity of SENS and its simplification were studied by comparing their ability to differentiate between the COBRA and sulfasalazine arms. Responsiveness was studied by comparing standardized change scores between versions. SENS data showed good fit to the IRT model. Carpal and feet joints contributed the least statistical information to both erosion and joint space narrowing scores. Omitting the joints of the foot reduced measurement precision for the erosion score in cases with below-average levels of structural damage (relative efficiency compared with the original version ranged 35-59%). Omitting the carpal joints had minimal effect on precision (relative efficiency range 77-88%). Responsiveness of a simplified SENS without carpal joints closely approximated the original version (i.e., all Δ standardized change scores were ≤0.06). Discriminant validity was also similar between versions for both the erosion score (relative efficiency = 97%) and the SENS total score (relative efficiency = 84%). Our results show that the carpal joints may be omitted from the SENS without notable repercussion for its measurement performance. © 2016, American College of Rheumatology.

The Application of a Massively Parallel Computer to the Simulation of Electrical Wave Propagation Phenomena in the Heart Muscle Using Simplified Models

NASA Technical Reports Server (NTRS)

Karpoukhin, Mikhii G.; Kogan, Boris Y.; Karplus, Walter J.

1995-01-01

The simulation of heart arrhythmia and fibrillation are very important and challenging tasks. The solution of these problems using sophisticated mathematical models is beyond the capabilities of modern super computers. To overcome these difficulties it is proposed to break the whole simulation problem into two tightly coupled stages: generation of the action potential using sophisticated models. and propagation of the action potential using simplified models. The well known simplified models are compared and modified to bring the rate of depolarization and action potential duration restitution closer to reality. The modified method of lines is used to parallelize the computational process. The conditions for the appearance of 2D spiral waves after the application of a premature beat and the subsequent traveling of the spiral wave inside the simulated tissue are studied.

A Multi-Resolution Data Structure for Two-Dimensional Morse Functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bremer, P-T; Edelsbrunner, H; Hamann, B

2003-07-30

The efficient construction of simplified models is a central problem in the field of visualization. We combine topological and geometric methods to construct a multi-resolution data structure for functions over two-dimensional domains. Starting with the Morse-Smale complex we build a hierarchy by progressively canceling critical points in pairs. The data structure supports mesh traversal operations similar to traditional multi-resolution representations.

Towards a standard design model for quad-rotors: A review of current models, their accuracy and a novel simplified model

NASA Astrophysics Data System (ADS)

Amezquita-Brooks, Luis; Liceaga-Castro, Eduardo; Gonzalez-Sanchez, Mario; Garcia-Salazar, Octavio; Martinez-Vazquez, Daniel

2017-11-01

Applications based on quad-rotor-vehicles (QRV) are becoming increasingly wide-spread. Many of these applications require accurate mathematical representations for control design, simulation and estimation. However, there is no consensus on a standardized model for these purposes. In this article a review of the most common elements included in QRV models reported in the literature is presented. This survey shows that some elements are recurrent for typical non-aerobatic QRV applications; in particular, for control design and high-performance simulation. By synthesising the common features of the reviewed models a standard generic model SGM is proposed. The SGM is cast as a typical state-space model without memory-less transformations, a structure which is useful for simulation and controller design. The survey also shows that many QRV applications use simplified representations, which may be considered simplifications of the SGM here proposed. In order to assess the effectiveness of the simplified models, a comprehensive comparison based on digital simulations is presented. With this comparison, it is possible to determine the accuracy of each model under particular operating ranges. Such information is useful for the selection of a model according to a particular application. In addition to the models found in the literature, in this article a novel simplified model is derived. The main characteristics of this model are that its inner dynamics are linear, it has low complexity and it has a high level of accuracy in all the studied operating ranges, a characteristic found only in more complex representations. To complement the article the main elements of the SGM are evaluated with the aid of experimental data and the computational complexity of all surveyed models is briefly analysed. Finally, the article presents a discussion on how the structural characteristics of the models are useful to suggest particular QRV control structures.

Application of a passivity based control methodology for flexible joint robots to a simplified Space Shuttle RMS

NASA Technical Reports Server (NTRS)

Sicard, Pierre; Wen, John T.

1992-01-01

A passivity approach for the control design of flexible joint robots is applied to the rate control of a three-link arm modeled after the shoulder yaw joint of the Space Shuttle Remote Manipulator System (RMS). The system model includes friction and elastic joint couplings modeled as nonlinear springs. The basic structure of the proposed controller is the sum of a model-based feedforward and a model-independent feedback. A regulator approach with link state feedback is employed to define the desired motor state. Passivity theory is used to design a motor state-based controller to stabilize the error system formed by the feedforward. Simulation results show that greatly improved performance was obtained by using the proposed controller over the existing RMS controller.

Most recent common ancestor probability distributions in gene genealogies under selection.

PubMed

Slade, P F

2000-12-01

A computational study is made of the conditional probability distribution for the allelic type of the most recent common ancestor in genealogies of samples of n genes drawn from a population under selection, given the initial sample configuration. Comparisons with the corresponding unconditional cases are presented. Such unconditional distributions differ from samples drawn from the unique stationary distribution of population allelic frequencies, known as Wright's formula, and are quantified. Biallelic haploid and diploid models are considered. A simplified structure for the ancestral selection graph of S. M. Krone and C. Neuhauser (1997, Theor. Popul. Biol. 51, 210-237) is enhanced further, reducing the effective branching rate in the graph. This improves efficiency of such a nonneutral analogue of the coalescent for use with computational likelihood-inference techniques.

Neutron residual stress measurement and numerical modeling in a curved thin-walled structure by laser powder bed fusion additive manufacturing

DOE PAGES

An, Ke; Yuan, Lang; Dial, Laura; ...

2017-09-11

Severe residual stresses in metal parts made by laser powder bed fusion additive manufacturing processes (LPBFAM) can cause both distortion and cracking during the fabrication processes. Limited data is currently available for both iterating through process conditions and design, and in particular, for validating numerical models to accelerate process certification. In this work, residual stresses of a curved thin-walled structure, made of Ni-based superalloy Inconel 625™ and fabricated by LPBFAM, were resolved by neutron diffraction without measuring the stress-free lattices along both the build and the transverse directions. The stresses of the entire part during fabrication and after cooling downmore » were predicted by a simplified layer-by-layer finite element based numerical model. The simulated and measured stresses were found in good quantitative agreement. The validated simplified simulation methodology will allow to assess residual stresses in more complex structures and to significantly reduce manufacturing cycle time.« less

Simplified and refined structural modeling for economical flutter analysis and design

NASA Technical Reports Server (NTRS)

Ricketts, R. H.; Sobieszczanski, J.

1977-01-01

A coordinated use of two finite-element models of different levels of refinement is presented to reduce the computer cost of the repetitive flutter analysis commonly encountered in structural resizing to meet flutter requirements. One model, termed a refined model (RM), represents a high degree of detail needed for strength-sizing and flutter analysis of an airframe. The other model, called a simplified model (SM), has a relatively much smaller number of elements and degrees-of-freedom. A systematic method of deriving an SM from a given RM is described. The method consists of judgmental and numerical operations to make the stiffness and mass of the SM elements equivalent to the corresponding substructures of RM. The structural data are automatically transferred between the two models. The bulk of analysis is performed on the SM with periodical verifications carried out by analysis of the RM. In a numerical example of a supersonic cruise aircraft with an arrow wing, this approach permitted substantial savings in computer costs and acceleration of the job turn-around.

Neutron residual stress measurement and numerical modeling in a curved thin-walled structure by laser powder bed fusion additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Ke; Yuan, Lang; Dial, Laura

Severe residual stresses in metal parts made by laser powder bed fusion additive manufacturing processes (LPBFAM) can cause both distortion and cracking during the fabrication processes. Limited data is currently available for both iterating through process conditions and design, and in particular, for validating numerical models to accelerate process certification. In this work, residual stresses of a curved thin-walled structure, made of Ni-based superalloy Inconel 625™ and fabricated by LPBFAM, were resolved by neutron diffraction without measuring the stress-free lattices along both the build and the transverse directions. The stresses of the entire part during fabrication and after cooling downmore » were predicted by a simplified layer-by-layer finite element based numerical model. The simulated and measured stresses were found in good quantitative agreement. The validated simplified simulation methodology will allow to assess residual stresses in more complex structures and to significantly reduce manufacturing cycle time.« less

Transient dynamic analysis of the Bao'An Stadium

NASA Astrophysics Data System (ADS)

Knight, David; Whitefield, Rowan; Nhieu, Eric; Tahmasebinia, Faham; Ansourian, Peter; Alonso-Marroquin, Fernando

2016-08-01

Bao'An Stadium is a unique structure that utilises 54m span cantilevers with tensioned members to support the roof. This report involves a simplified finite element model of Bao'An stadium using Strand7 to analyse the effects of deflections, buckling and earthquake loading. Modelling the cantilevers of the original structure with a double curvature was problematic due to unrealistic deflections and no total mass participation using the Spectral Response Solver. To rectify this, a simplified symmetrical stadium was created and the cable free length attribute was used to induce tension in the inner ring and bottom chord members to create upwards deflection. Further, in place of the Spectral Response Solver, the Transient Linear Dynamic Solver was inputted with an El-Centro earthquake. The stadium's response to a 0.20g earthquake and self-weight indicated the deflections satisfied AS1170.0, the loading in the columns was below the critical buckling load, and all structural members satisfied AS4100.

Dynamic behaviour of thin composite plates for different boundary conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sprintu, Iuliana, E-mail: sprintui@yahoo.com, E-mail: rotaruconstantin@yahoo.com; Rotaru, Constantin, E-mail: sprintui@yahoo.com, E-mail: rotaruconstantin@yahoo.com

2014-12-10

In the context of composite materials technology, which is increasingly present in industry, this article covers a topic of great interest and theoretical and practical importance. Given the complex design of fiber-reinforced materials and their heterogeneous nature, mathematical modeling of the mechanical response under different external stresses is very difficult to address in the absence of simplifying assumptions. In most structural applications, composite structures can be idealized as beams, plates, or shells. The analysis is reduced from a three-dimensional elasticity problem to a oneor two-dimensional problem, based on certain simplifying assumptions that can be made because the structure is thin.more » This paper aims to validate a mathematical model illustrating how thin rectangular orthotropic plates respond to the actual load. Thus, from the theory of thin plates, new analytical solutions are proposed corresponding to orthotropic rectangular plates having different boundary conditions. The proposed analytical solutions are considered both for solving equation orthotropic rectangular plates and for modal analysis.« less

A simplified implementation of van der Waals density functionals for first-principles molecular dynamics applications

NASA Astrophysics Data System (ADS)

Wu, Jun; Gygi, François

2012-06-01

We present a simplified implementation of the non-local van der Waals correlation functional introduced by Dion et al. [Phys. Rev. Lett. 92, 246401 (2004)] and reformulated by Román-Pérez et al. [Phys. Rev. Lett. 103, 096102 (2009)]. The proposed numerical approach removes the logarithmic singularity of the kernel function. Complete expressions of the self-consistent correlation potential and of the stress tensor are given. Combined with various choices of exchange functionals, five versions of van der Waals density functionals are implemented. Applications to the computation of the interaction energy of the benzene-water complex and to the computation of the equilibrium cell parameters of the benzene crystal are presented. As an example of crystal structure calculation involving a mixture of hydrogen bonding and dispersion interactions, we compute the equilibrium structure of two polymorphs of aspirin (2-acetoxybenzoic acid, C9H8O4) in the P21/c monoclinic structure.

Interactive Physical Simulation of Catheter Motion within Mayor Vessel Structures and Cavities for ASD/VSD Treatment

NASA Astrophysics Data System (ADS)

Becherer, Nico; Hesser, Jürgen; Kornmesser, Ulrike; Schranz, Dietmar; Männer, Reinhard

2007-03-01

Simulation systems are becoming increasingly essential in medical education. Hereby, capturing the physical behaviour of the real world requires a sophisticated modelling of instruments within the virtual environment. Most models currently used are not capable of user interactive simulations due to the computation of the complex underlying analytical equations. Alternatives are often based on simplifying mass-spring systems, being able to deliver high update rates that come at the cost of less realistic motion. In addition, most techniques are limited to narrow and tubular vessel structures or restrict shape alterations to two degrees of freedom, not allowing instrument deformations like torsion. In contrast, our approach combines high update rates with highly realistic motion and can in addition be used with respect to arbitrary structures like vessels or cavities (e.g. atrium, ventricle) without limiting the degrees of freedom. Based on energy minimization, bending energies and vessel structures are considered as linear elastic elements; energies are evaluated at regularly spaced points on the instrument, while the distance of the points is fixed, i.e. we simulate an articulated structure of joints with fixed connections between them. Arbitrary tissue structures are modeled through adaptive distance fields and are connected by nodes via an undirected graph system. The instrument points are linked to nodes by a system of rules. Energy minimization uses a Quasi Newton method without preconditioning and, hereby, gradients are estimated using a combination of analytical and numerical terms. Results show a high quality in motion simulation when compared to a phantom model. The approach is also robust and fast. Simulating an instrument with 100 joints runs at 100 Hz on a 3 GHz PC.

Highly efficient blue and warm white organic light-emitting diodes with a simplified structure

NASA Astrophysics Data System (ADS)

Li, Xiang-Long; Ouyang, Xinhua; Chen, Dongcheng; Cai, Xinyi; Liu, Ming; Ge, Ziyi; Cao, Yong; Su, Shi-Jian

2016-03-01

Two blue fluorescent emitters were utilized to construct simplified organic light-emitting diodes (OLEDs) and the remarkable difference in device performance was carefully illustrated. A maximum current efficiency of 4.84 cd A-1 (corresponding to a quantum efficiency of 4.29%) with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.144, 0.127) was achieved by using N,N-diphenyl-4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1, 1‧:4‧, 1″-terphenyl]-4-amine (BBPI) as a non-doped emission layer of the simplified blue OLEDs without carrier-transport layers. In addition, simplified fluorescent/phosphorescent (F/P) hybrid warm white OLEDs without carrier-transport layers were fabricated by utilizing BBPI as (1) the blue emitter and (2) the host of a complementary yellow phosphorescent emitter (PO-01). A maximum current efficiency of 36.8 cd A-1 and a maximum power efficiency of 38.6 lm W-1 were achieved as a result of efficient energy transfer from the host to the guest and good triplet exciton confinement on the phosphorescent molecules. The blue and white OLEDs are among the most efficient simplified fluorescent blue and F/P hybrid white devices, and their performance is even comparable to that of most previously reported complicated multi-layer devices with carrier-transport layers.

A simplified analytical solution for thermal response of a one-dimensional, steady state transpiration cooling system in radiative and convective environment

NASA Technical Reports Server (NTRS)

Kubota, H.

1976-01-01

A simplified analytical method for calculation of thermal response within a transpiration-cooled porous heat shield material in an intense radiative-convective heating environment is presented. The essential assumptions of the radiative and convective transfer processes in the heat shield matrix are the two-temperature approximation and the specified radiative-convective heatings of the front surface. Sample calculations for porous silica with CO2 injection are presented for some typical parameters of mass injection rate, porosity, and material thickness. The effect of these parameters on the cooling system is discussed.

A modified approach to controller partitioning

NASA Technical Reports Server (NTRS)

Garg, Sanjay; Veillette, Robert J.

1993-01-01

The idea of computing a decentralized control law for the integrated flight/propulsion control of an aircraft by partitioning a given centralized controller is investigated. An existing controller partitioning methodology is described, and a modified approach is proposed with the objective of simplifying the associated controller approximation problem. Under the existing approach, the decentralized control structure is a variable in the partitioning process; by contrast, the modified approach assumes that the structure is fixed a priori. Hence, the centralized controller design may take the decentralized control structure into account. Specifically, the centralized controller may be designed to include all the same inputs and outputs as the decentralized controller; then, the two controllers may be compared directly, simplifying the partitioning process considerably. Following the modified approach, a centralized controller is designed for an example aircraft mode. The design includes all the inputs and outputs to be used in a specified decentralized control structure. However, it is shown that the resulting centralized controller is not well suited for approximation by a decentralized controller of the given structure. The results indicate that it is not practical in general to cast the controller partitioning problem as a direct controller approximation problem.

Simplified method to solve sound transmission through structures lined with elastic porous material.

PubMed

Lee, J H; Kim, J

2001-11-01

An approximate analysis method is developed to calculate sound transmission through structures lined with porous material. Because the porous material has both the solid phase and fluid phase, three wave components exist in the material, which makes the related analysis very complicated. The main idea in developing the approximate method is very simple: modeling the porous material using only the strongest of the three waves, which in effect idealizes the material as an equivalent fluid. The analysis procedure has to be conducted in two steps. In the first step, sound transmission through a flat double panel with a porous liner of infinite extents, which has the same cross sectional construction as the actual structure, is solved based on the full theory and the strongest wave component is identified. In the second step sound transmission through the actual structure is solved modeling the porous material as an equivalent fluid while using the actual geometry of the structure. The development and validation of the method are discussed in detail. As an application example, the transmission loss through double walled cylindrical shells with a porous core is calculated utilizing the simplified method.

Examination of simplified travel demand model. [Internal volume forecasting model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R.L. Jr.; McFarlane, W.J.

1978-01-01

A simplified travel demand model, the Internal Volume Forecasting (IVF) model, proposed by Low in 1972 is evaluated as an alternative to the conventional urban travel demand modeling process. The calibration of the IVF model for a county-level study area in Central Wisconsin results in what appears to be a reasonable model; however, analysis of the structure of the model reveals two primary mis-specifications. Correction of the mis-specifications leads to a simplified gravity model version of the conventional urban travel demand models. Application of the original IVF model to ''forecast'' 1960 traffic volumes based on the model calibrated for 1970more » produces accurate estimates. Shortcut and ad hoc models may appear to provide reasonable results in both the base and horizon years; however, as shown by the IVF mode, such models will not always provide a reliable basis for transportation planning and investment decisions.« less

Simplified Model and Response Analysis for Crankshaft of Air Compressor

NASA Astrophysics Data System (ADS)

Chao-bo, Li; Jing-jun, Lou; Zhen-hai, Zhang

2017-11-01

The original model of crankshaft is simplified to the appropriateness to balance the calculation precision and calculation speed, and then the finite element method is used to analyse the vibration response of the structure. In order to study the simplification and stress concentration for crankshaft of air compressor, this paper compares calculative mode frequency and experimental mode frequency of the air compressor crankshaft before and after the simplification, the vibration response of reference point constraint conditions is calculated by using the simplified model, and the stress distribution of the original model is calculated. The results show that the error between calculative mode frequency and experimental mode frequency is controlled in less than 7%, the constraint will change the model density of the system, the position between the crank arm and the shaft appeared stress concentration, so the part of the crankshaft should be treated in the process of manufacture.

GoPros™ as an underwater photogrammetry tool for citizen science

PubMed Central

David, Peter A.; Dupont, Sally F.; Mathewson, Ciaran P.; O’Neill, Samuel J.; Powell, Nicholas N.; Williamson, Jane E.

2016-01-01

Citizen science can increase the scope of research in the marine environment; however, it suffers from necessitating specialized training and simplified methodologies that reduce research output. This paper presents a simplified, novel survey methodology for citizen scientists, which combines GoPro imagery and structure from motion to construct an ortho-corrected 3D model of habitats for analysis. Results using a coral reef habitat were compared to surveys conducted with traditional snorkelling methods for benthic cover, holothurian counts, and coral health. Results were comparable between the two methods, and structure from motion allows the results to be analysed off-site for any chosen visual analysis. The GoPro method outlined in this study is thus an effective tool for citizen science in the marine environment, especially for comparing changes in coral cover or volume over time. PMID:27168973

GoPros™ as an underwater photogrammetry tool for citizen science.

PubMed

Raoult, Vincent; David, Peter A; Dupont, Sally F; Mathewson, Ciaran P; O'Neill, Samuel J; Powell, Nicholas N; Williamson, Jane E

2016-01-01

Citizen science can increase the scope of research in the marine environment; however, it suffers from necessitating specialized training and simplified methodologies that reduce research output. This paper presents a simplified, novel survey methodology for citizen scientists, which combines GoPro imagery and structure from motion to construct an ortho-corrected 3D model of habitats for analysis. Results using a coral reef habitat were compared to surveys conducted with traditional snorkelling methods for benthic cover, holothurian counts, and coral health. Results were comparable between the two methods, and structure from motion allows the results to be analysed off-site for any chosen visual analysis. The GoPro method outlined in this study is thus an effective tool for citizen science in the marine environment, especially for comparing changes in coral cover or volume over time.

Simplifying microbial electrosynthesis reactor design.

PubMed

Giddings, Cloelle G S; Nevin, Kelly P; Woodward, Trevor; Lovley, Derek R; Butler, Caitlyn S

2015-01-01

Microbial electrosynthesis, an artificial form of photosynthesis, can efficiently convert carbon dioxide into organic commodities; however, this process has only previously been demonstrated in reactors that have features likely to be a barrier to scale-up. Therefore, the possibility of simplifying reactor design by both eliminating potentiostatic control of the cathode and removing the membrane separating the anode and cathode was investigated with biofilms of Sporomusa ovata. S. ovata reduces carbon dioxide to acetate and acts as the microbial catalyst for plain graphite stick cathodes as the electron donor. In traditional 'H-cell' reactors, where the anode and cathode chambers were separated with a proton-selective membrane, the rates and columbic efficiencies of microbial electrosynthesis remained high when electron delivery at the cathode was powered with a direct current power source rather than with a potentiostat-poised cathode utilized in previous studies. A membrane-less reactor with a direct-current power source with the cathode and anode positioned to avoid oxygen exposure at the cathode, retained high rates of acetate production as well as high columbic and energetic efficiencies. The finding that microbial electrosynthesis is feasible without a membrane separating the anode from the cathode, coupled with a direct current power source supplying the energy for electron delivery, is expected to greatly simplify future reactor design and lower construction costs.

Inverse correlation between the standard deviation of R-R intervals in supine position and the simplified menopausal index in women with climacteric symptoms.

PubMed

Yanagihara, Nobuyuki; Seki, Meikan; Nakano, Masahiro; Hachisuga, Toru; Goto, Yukio

2014-06-01

Disturbance of autonomic nervous activity has been thought to play a role in the climacteric symptoms of postmenopausal women. This study was therefore designed to investigate the relationship between autonomic nervous activity and climacteric symptoms in postmenopausal Japanese women. The autonomic nervous activity of 40 Japanese women with climacteric symptoms and 40 Japanese women without climacteric symptoms was measured by power spectral analysis of heart rate variability using a standard hexagonal radar chart. The scores for climacteric symptoms were determined using the simplified menopausal index. Sympathetic excitability and irritability, as well as the standard deviation of mean R-R intervals in supine position, were significantly (P < 0.01, 0.05, and 0.001, respectively) decreased in women with climacteric symptoms. There was a negative correlation between the standard deviation of mean R-R intervals in supine position and the simplified menopausal index score. The lack of control for potential confounding variables was a limitation of this study. In climacteric women, the standard deviation of mean R-R intervals in supine position is negatively correlated with the simplified menopausal index score.

Application of a simplified theory of ELF propagation to a simplified worldwide model of the ionosphere

NASA Astrophysics Data System (ADS)

Behroozi-Toosi, A. B.; Booker, H. G.

1980-12-01

The simplified theory of ELF wave propagation in the earth-ionosphere transmission lines developed by Booker (1980) is applied to a simplified worldwide model of the ionosphere. The theory, which involves the comparison of the local vertical refractive index gradient with the local wavelength in order to classify the altitude into regions of low and high gradient, is used for a model of electron and negative ion profiles in the D and E regions below 150 km. Attention is given to the frequency dependence of ELF propagation at a middle latitude under daytime conditions, the daytime latitude dependence of ELF propagation at the equinox, the effects of sunspot, seasonal and diurnal variations on propagation, nighttime propagation neglecting and including propagation above 100 km, and the effect on daytime ELF propagation of a sudden ionospheric disturbance. The numerical values obtained by the method for the propagation velocity and attenuation rate are shown to be in general agreement with the analytic Naval Ocean Systems Center computer program. It is concluded that the method employed gives more physical insights into propagation processes than any other method, while requiring less effort and providing maximal accuracy.

Impact of Moist Physics Complexity on Tropical Cyclone Simulations from the Hurricane Weather Research and Forecast System

NASA Astrophysics Data System (ADS)

Kalina, E. A.; Biswas, M.; Newman, K.; Grell, E. D.; Bernardet, L.; Frimel, J.; Carson, L.

2017-12-01

The parameterization of moist physics in numerical weather prediction models plays an important role in modulating tropical cyclone structure, intensity, and evolution. The Hurricane Weather Research and Forecast system (HWRF), the National Oceanic and Atmospheric Administration's operational model for tropical cyclone prediction, uses the Scale-Aware Simplified Arakawa-Schubert (SASAS) cumulus scheme and a modified version of the Ferrier-Aligo (FA) microphysics scheme to parameterize moist physics. The FA scheme contains a number of simplifications that allow it to run efficiently in an operational setting, which includes prescribing values for hydrometeor number concentrations (i.e., single-moment microphysics) and advecting the total condensate rather than the individual hydrometeor species. To investigate the impact of these simplifying assumptions on the HWRF forecast, the FA scheme was replaced with the more complex double-moment Thompson microphysics scheme, which individually advects cloud ice, cloud water, rain, snow, and graupel. Retrospective HWRF forecasts of tropical cyclones that occurred in the Atlantic and eastern Pacific ocean basins from 2015-2017 were then simulated and compared to those produced by the operational HWRF configuration. Both traditional model verification metrics (i.e., tropical cyclone track and intensity) and process-oriented metrics (e.g., storm size, precipitation structure, and heating rates from the microphysics scheme) will be presented and compared. The sensitivity of these results to the cumulus scheme used (i.e., the operational SASAS versus the Grell-Freitas scheme) also will be examined. Finally, the merits of replacing the moist physics schemes that are used operationally with the alternatives tested here will be discussed from a standpoint of forecast accuracy versus computational resources.

Curves showing column strength of steel and duralumin tubing

NASA Technical Reports Server (NTRS)

Ross, Orrin E

1929-01-01

Given here are a set of column strength curves that are intended to simplify the method of determining the size of struts in an airplane structure when the load in the member is known. The curves will also simplify the checking of the strength of a strut if the size and length are known. With these curves, no computations are necessary, as in the case of the old-fashioned method of strut design. The process is so simple that draftsmen or others who are not entirely familiar with mechanics can check the strength of a strut without much danger of error.

Shape control of large space structures

NASA Technical Reports Server (NTRS)

Hagan, M. T.

1982-01-01

A survey has been conducted to determine the types of control strategies which have been proposed for controlling the vibrations in large space structures. From this survey several representative control strategies were singled out for detailed analyses. The application of these strategies to a simplified model of a large space structure has been simulated. These simulations demonstrate the implementation of the control algorithms and provide a basis for a preliminary comparison of their suitability for large space structure control.

Communication: The simplified generalized entropy theory of glass-formation in polymer melts.

PubMed

Freed, Karl F

2015-08-07

While a wide range of non-trivial predictions of the generalized entropy theory (GET) of glass-formation in polymer melts agree with a large number of observed universal and non-universal properties of these glass-formers and even for the dependence of these properties on monomer molecular structure, the huge mathematical complexity of the theory precludes its extension to describe, for instance, the perplexing, complex behavior observed for technologically important polymer films with thickness below ∼100 nm and for which a fundamental molecular theory is lacking for the structural relaxation. The present communication describes a hugely simplified version of the theory, called the simplified generalized entropy theory (SGET) that provides one component necessary for devising a theory for the structural relaxation of thin polymer films and thereby supplements the first required ingredient, the recently developed Flory-Huggins level theory for the thermodynamic properties of thin polymer films, before the concluding third step of combining all the components into the SGET for thin polymer films. Comparisons between the predictions of the SGET and the full GET for the four characteristic temperatures of glass-formation provide good agreement for a highly non-trivial model system of polymer melts with chains of the structure of poly(n-α olefins) systems where the GET has produced good agreement with experiment. The comparisons consider values of the relative backbone and side group stiffnesses such that the glass transition temperature decreases as the amount of excess free volume diminishes, contrary to general expectations but in accord with observations for poly(n-alkyl methacrylates). Moreover, the SGET is sufficiently concise to enable its discussion in a standard course on statistical mechanics or polymer physics.

Non-Optical Applications of Photonic Crystal Structures

DTIC Science & Technology

2005-02-23

antenna created by covering a metallic ground plane with a periodic band-gap structure. By incorporating varactor diodes into the structure, they have...defects can be created in alumina band-gap materials by use of laser machining. (a) 1ncalizcd A 1II Cavity Fig 10 - (a) Schematics of propagation of...The primary applications are in dentistry and dermatology . The scale length of Terahertz devices simplifies the problems of fabrication and

A Fast Proceduere for Optimizing Thermal Protection Systems of Re-Entry Vehicles

NASA Astrophysics Data System (ADS)

Ferraiuolo, M.; Riccio, A.; Tescione, D.; Gigliotti, M.

The aim of the present work is to introduce a fast procedure to optimize thermal protection systems for re-entry vehicles subjected to high thermal loads. A simplified one-dimensional optimization process, performed in order to find the optimum design variables (lengths, sections etc.), is the first step of the proposed design procedure. Simultaneously, the most suitable materials able to sustain high temperatures and meeting the weight requirements are selected and positioned within the design layout. In this stage of the design procedure, simplified (generalized plane strain) FEM models are used when boundary and geometrical conditions allow the reduction of the degrees of freedom. Those simplified local FEM models can be useful because they are time-saving and very simple to build; they are essentially one dimensional and can be used for optimization processes in order to determine the optimum configuration with regard to weight, temperature and stresses. A triple-layer and a double-layer body, subjected to the same aero-thermal loads, have been optimized to minimize the overall weight. Full two and three-dimensional analyses are performed in order to validate those simplified models. Thermal-structural analyses and optimizations are executed by adopting the Ansys FEM code.

A User's Guide to Topological Data Analysis

ERIC Educational Resources Information Center

Munch, Elizabeth

2017-01-01

Topological data analysis (TDA) is a collection of powerful tools that can quantify shape and structure in data in order to answer questions from the data's domain. This is done by representing some aspect of the structure of the data in a simplified topological signature. In this article, we introduce two of the most commonly used topological…

Collaborative Modelling of the Vascular System--Designing and Evaluating a New Learning Method for Secondary Students

ERIC Educational Resources Information Center

Haugwitz, Marion; Sandmann, Angela

2010-01-01

Understanding biological structures and functions is often difficult because of their complexity and micro-structure. For example, the vascular system is a complex and only partly visible system. Constructing models to better understand biological functions is seen as a suitable learning method. Models function as simplified versions of real…

Extensions and evaluations of a general quantitative theory of forest structure and dynamics

PubMed Central

Enquist, Brian J.; West, Geoffrey B.; Brown, James H.

2009-01-01

Here, we present the second part of a quantitative theory for the structure and dynamics of forests under demographic and resource steady state. The theory is based on individual-level allometric scaling relations for how trees use resources, fill space, and grow. These scale up to determine emergent properties of diverse forests, including size–frequency distributions, spacing relations, canopy configurations, mortality rates, population dynamics, successional dynamics, and resource flux rates. The theory uniquely makes quantitative predictions for both stand-level scaling exponents and normalizations. We evaluate these predictions by compiling and analyzing macroecological datasets from several tropical forests. The close match between theoretical predictions and data suggests that forests are organized by a set of very general scaling rules. Our mechanistic theory is based on allometric scaling relations, is complementary to “demographic theory,” but is fundamentally different in approach. It provides a quantitative baseline for understanding deviations from predictions due to other factors, including disturbance, variation in branching architecture, asymmetric competition, resource limitation, and other sources of mortality, which are not included in the deliberately simplified theory. The theory should apply to a wide range of forests despite large differences in abiotic environment, species diversity, and taxonomic and functional composition. PMID:19363161

Measured and calculated acoustic attenuation rates of tuned resonator arrays for two surface impedance distribution models with flow

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Abrahamson, A. Louis; Jones, Michael G.

1988-01-01

An experiment was performed to validate two analytical models for predicting low frequency attenuation of duct liner configurations built from an array of seven resonators that could be individually tuned via adjustable cavity depths. These analytical models had previously been developed for high frequency aero-engine inlet duct liner design. In the low frequency application, the liner surface impedance distribution is unavoidably spatially varying by virtue of available fabrication techniques. The characteristic length of this spatial variation may be a significant fraction of the acoustic wavelength. Comparison of measured and predicted attenuation rates and transmission losses for both modal decomposition and finite element propagation models were in good to excellent agreement for a test frequency range that included the first and second cavity resonance frequencies. This was true for either of two surface impedance distribution modeling procedures used to simplify the impedance boundary conditions. In the presence of mean flow, measurements revealed a fine scale structure of acoustic hot spots in the attenuation and phase profiles. These details were accurately predicted by the finite element model. Since no impedance changes due to mean flow were assumed, it is concluded that this fine scale structure was due to convective effects of the mean flow interacting with the surface impedance nonuniformities.

Feasibility of implementation of a "simplified, No-X-Ray, no-lead apron, two-catheter approach" for ablation of supraventricular arrhythmias in children and adults.

PubMed

Stec, Sebastian; Śledź, Janusz; Mazij, Mariusz; Raś, Małgorzata; Ludwik, Bartosz; Chrabąszcz, Michał; Śledź, Arkadiusz; Banasik, Małgorzata; Bzymek, Magdalena; Młynarczyk, Krzysztof; Deutsch, Karol; Labus, Michał; Śpikowski, Jerzy; Szydłowski, Lesław

2014-08-01

Although the "near-zero-X-Ray" or "No-X-Ray" catheter ablation (CA) approach has been reported for treatment of various arrhythmias, few prospective studies have strictly used "No-X-Ray," simplified 2-catheter approaches for CA in patients with supraventricular tachycardia (SVT). We assessed the feasibility of a minimally invasive, nonfluoroscopic (MINI) CA approach in such patients. Data were obtained from a prospective multicenter CA registry of patients with regular SVTs. After femoral access, 2 catheters were used to create simple, 3D electroanatomic maps and to perform electrophysiologic studies. Medical staff did not use lead aprons after the first 10 MINI CA cases. A total of 188 patients (age, 45 ± 21 years; 17% <19 years; 55% women) referred for the No-X-Ray approach were included. They were compared to 714 consecutive patients referred for a simplified approach using X-rays (age, 52 ± 18 years; 7% <19 years; 55% women). There were 9 protocol exceptions that necessitated the use of X-rays. Ultimately, 179/188 patients underwent the procedure without fluoroscopy, with an acute success rate of 98%. The procedure times (63 ± 26 vs. 63 ± 29 minutes, P > 0.05), major complications (0% vs. 0%, P > 0.05) and acute (98% vs. 98%, P > 0.05) and long-term (93% vs. 94%, P > 0.05) success rates were similar in the "No-X-Ray" and control groups. Implementation of a strict "No-X-Ray, simplified 2-catheter" CA approach is safe and effective in majority of the patients with SVT. This modified approach for SVTs should be prospectively validated in a multicenter study. © 2014 Wiley Periodicals, Inc.

Evaluation of the upconversion mechanisms in Ho3+-doped crystals: Experiment and theoretical modeling

NASA Astrophysics Data System (ADS)

Osiac, E.; Sokólska, I.; Kück, S.

2002-06-01

The paper compares the mechanisms that enable the upconverted green emission (5S2-->5I8) of the Ho3+ ion under infrared excitation (700-920 nm) in several crystalline hosts (YAlO3, YLiF4, Y3Sc2Ga3O12, and BaY2F8). Parameters involved in the upconversion such as excited-state absorption and cross-relaxation rates were determined from spectroscopic measurements. A system of differential equation (rate equations) was used to describe the upconversion mechanism and was numerically solved. The results were compared with experimental data. A reduction of this system to a three-level ``simplified system'' is presented, which includes only the ground level, the emitting level, and the intermediate level. The differences between the photon-avalanche mechanism and the looping mechanism are discussed and analyzed according to this simplified system.

Aspects of Cool-Flame Supported Droplet Combustion in Microgravity

NASA Technical Reports Server (NTRS)

Nayagam, Vedha; Dietrich, Daniel L.; Williams, Forman A.

2015-01-01

Droplet combustion experiments performed on board the International Space Station have shown that normal-alkane fuels with negative temperature coefficient (NTC) chemistry can support quasi-steady, low-temperature combustion without any visible flame. Here we review the results for n-decane, n-heptane, and n-octane droplets burning in carbon dioxidehelium diluted environments at different pressures and initial droplet sizes. Experimental results for cool-flame burning rates, flame standoff ratios, and extinction diameters are compared against simplified theoretical models of the phenomenon. A simplified quasi-steady model based on the partial-burning regime of Lin predicts the burning rate, and flame standoff ratio reasonably well for all three normal alkanes. The second-stage cool-flame burning and extinction following the first-stage hot-flame combustion, however, shows a small dependence on the initial droplet size, thus deviating from the quasi-steady results. An asymptotic model that estimates the oxygen depletion by the hot flame and its influence on cool-flame burning rates is shown to correct the quasi-steady results and provide a better comparison with the measured burning-rate results.This work was supported by the NASA Space Life and Physical Sciences Research and Applications Program and the International Space Station Program.

Physical heterogeneity control on effective mineral dissolution rates

NASA Astrophysics Data System (ADS)

Jung, Heewon; Navarre-Sitchler, Alexis

2018-04-01

Hydrologic heterogeneity may be an important factor contributing to the discrepancy in laboratory and field measured dissolution rates, but the governing factors influencing mineral dissolution rates among various representations of physical heterogeneity remain poorly understood. Here, we present multiple reactive transport simulations of anorthite dissolution in 2D latticed random permeability fields and link the information from local grid scale (1 cm or 4 m) dissolution rates to domain-scale (1m or 400 m) effective dissolution rates measured by the flux-weighted average of an ensemble of flow paths. We compare results of homogeneous models to heterogeneous models with different structure and layered permeability distributions within the model domain. Chemistry is simplified to a single dissolving primary mineral (anorthite) distributed homogeneously throughout the domain and a single secondary mineral (kaolinite) that is allowed to dissolve or precipitate. Results show that increasing size in correlation structure (i.e. long integral scales) and high variance in permeability distribution are two important factors inducing a reduction in effective mineral dissolution rates compared to homogeneous permeability domains. Larger correlation structures produce larger zones of low permeability where diffusion is an important transport mechanism. Due to the increased residence time under slow diffusive transport, the saturation state of a solute with respect to a reacting mineral approaches equilibrium and reduces the reaction rate. High variance in permeability distribution favorably develops large low permeability zones that intensifies the reduction in mixing and effective dissolution rate. However, the degree of reduction in effective dissolution rate observed in 1 m × 1 m domains is too small (<1% reduction from the corresponding homogeneous case) to explain several orders of magnitude reduction observed in many field studies. When multimodality in permeability distribution is approximated by high permeability variance in 400 m × 400 m domains, the reduction in effective dissolution rate increases due to the effect of long diffusion length scales through zones with very slow reaction rates. The observed scale dependence becomes complicated when pH dependent kinetics are compared to the results from pH independent rate constants. In small domains where the entire domain is reactive, faster anorthite dissolution rates and slower kaolinite precipitation rates relative to pH independent rates at far-from-equilibrium conditions reduce the effective dissolution rate by increasing the saturation state. However, in large domains where less- or non-reactive zones develop, higher kaolinite precipitation rates in less reactive zones increase the effective anorthite dissolution rates relative to the rates observed in pH independent cases.

Metal ion influence on eumelanin fluorescence and structure.

PubMed

Sutter, Jens-Uwe; Birch, David J S

2014-04-10

Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

Scenario analysis for techno-economic model development of U.S. offshore wind support structures

DOE PAGES

Damiani, Rick; Ning, Andrew; Maples, Ben; ...

2016-09-22

Challenging bathymetry and soil conditions of future US offshore wind power plants might promote the use of multimember, fixed-bottom structures (or 'jackets') in place of monopiles. Support structures affect costs associated with the balance of system and operation and maintenance. Understanding the link between these costs and the main environmental design drivers is crucial in the quest for a lower levelized cost of energy, and it is the main rationale for this work. Actual cost and engineering data are still scarce; hence, we evaluated a simplified engineering approach to tie key site and turbine parameters (e.g. water depth, wave height,more » tower-head mass, hub height and generator rating) to the overall support weight. A jacket-and-tower sizing tool, part of the National Renewable Energy Laboratory's system engineering software suite, was utilized to achieve mass-optimized support structures for 81 different configurations. This tool set provides preliminary sizing of all jacket components. Results showed reasonable agreement with the available industry data, and that the jacket mass is mainly driven by water depth, but hub height and tower-head mass become more influential at greater turbine ratings. A larger sensitivity of the structural mass to wave height and target eigenfrequency was observed for the deepest water conditions (>40 m). Thus, techno-economic analyses using this model should be based on accurate estimates of actual metocean conditions and turbine parameters especially for deep waters. Finally, the relationships derived from this study will inform National Renewable Energy Laboratory's offshore balance of system cost model, and they will be used to evaluate the impact of changes in technology on offshore wind lower levelized cost of energy.« less

Metal ion influence on eumelanin fluorescence and structure

NASA Astrophysics Data System (ADS)

Sutter, Jens-Uwe; Birch, David J. S.

2014-06-01

Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

Mode tuning of a simplified string instrument using time-dimensionless state-derivative control

NASA Astrophysics Data System (ADS)

Benacchio, Simon; Chomette, Baptiste; Mamou-Mani, Adrien; Finel, Victor

2015-01-01

In recent years, there has been a growing interest in smart structures, particularly in the field of musical acoustics. Control methods, initially developed to reduce vibration and damage, can be a good way to shift modal parameters of a structure in order to modify its dynamic response. This study focuses on smart musical instruments and aims to modify their radiated sound. This is achieved by controlling the modal parameters of the soundboard of a simplified string instrument. A method combining a pole placement algorithm and a time-dimensionless state-derivative control is used and quickly compared to a usual state control method. Then the effect of the mode tuning on the coupling between the string and the soundboard is experimentally studied. Controlling two vibration modes of the soundboard, its acoustic response and the damping of the third partial of the sound are modified. Finally these effects are listened in the radiated sound.

Coach simplified structure modeling and optimization study based on the PBM method

NASA Astrophysics Data System (ADS)

Zhang, Miaoli; Ren, Jindong; Yin, Ying; Du, Jian

2016-09-01

For the coach industry, rapid modeling and efficient optimization methods are desirable for structure modeling and optimization based on simplified structures, especially for use early in the concept phase and with capabilities of accurately expressing the mechanical properties of structure and with flexible section forms. However, the present dimension-based methods cannot easily meet these requirements. To achieve these goals, the property-based modeling (PBM) beam modeling method is studied based on the PBM theory and in conjunction with the characteristics of coach structure of taking beam as the main component. For a beam component of concrete length, its mechanical characteristics are primarily affected by the section properties. Four section parameters are adopted to describe the mechanical properties of a beam, including the section area, the principal moments of inertia about the two principal axles, and the torsion constant of the section. Based on the equivalent stiffness strategy, expressions for the above section parameters are derived, and the PBM beam element is implemented in HyperMesh software. A case is realized using this method, in which the structure of a passenger coach is simplified. The model precision is validated by comparing the basic performance of the total structure with that of the original structure, including the bending and torsion stiffness and the first-order bending and torsional modal frequencies. Sensitivity analysis is conducted to choose design variables. The optimal Latin hypercube experiment design is adopted to sample the test points, and polynomial response surfaces are used to fit these points. To improve the bending and torsion stiffness and the first-order torsional frequency and taking the allowable maximum stresses of the braking and left turning conditions as constraints, the multi-objective optimization of the structure is conducted using the NSGA-II genetic algorithm on the ISIGHT platform. The result of the Pareto solution set is acquired, and the selection strategy of the final solution is discussed. The case study demonstrates that the mechanical performances of the structure can be well-modeled and simulated by PBM beam. Because of the merits of fewer parameters and convenience of use, this method is suitable to be applied in the concept stage. Another merit is that the optimization results are the requirements for the mechanical performance of the beam section instead of those of the shape and dimensions, bringing flexibility to the succeeding design.

Flexible Data Link

DTIC Science & Technology

2015-04-01

DDC ) results in more complicated digital (FPGA) processing, yet simplifies the analog design significantly while improving the quality of the...Interleaved CP Cyclic Prefix DAC Digital to Analog Converter DDC Digital Down Converter DDR Double Data Rate DUC Digital Up Converter ENOB Effective

Machine learning methods can replace 3D profile method in classification of amyloidogenic hexapeptides.

PubMed

Stanislawski, Jerzy; Kotulska, Malgorzata; Unold, Olgierd

2013-01-17

Amyloids are proteins capable of forming fibrils. Many of them underlie serious diseases, like Alzheimer disease. The number of amyloid-associated diseases is constantly increasing. Recent studies indicate that amyloidogenic properties can be associated with short segments of aminoacids, which transform the structure when exposed. A few hundreds of such peptides have been experimentally found. Experimental testing of all possible aminoacid combinations is currently not feasible. Instead, they can be predicted by computational methods. 3D profile is a physicochemical-based method that has generated the most numerous dataset - ZipperDB. However, it is computationally very demanding. Here, we show that dataset generation can be accelerated. Two methods to increase the classification efficiency of amyloidogenic candidates are presented and tested: simplified 3D profile generation and machine learning methods. We generated a new dataset of hexapeptides, using more economical 3D profile algorithm, which showed very good classification overlap with ZipperDB (93.5%). The new part of our dataset contains 1779 segments, with 204 classified as amyloidogenic. The dataset of 6-residue sequences with their binary classification, based on the energy of the segment, was applied for training machine learning methods. A separate set of sequences from ZipperDB was used as a test set. The most effective methods were Alternating Decision Tree and Multilayer Perceptron. Both methods obtained area under ROC curve of 0.96, accuracy 91%, true positive rate ca. 78%, and true negative rate 95%. A few other machine learning methods also achieved a good performance. The computational time was reduced from 18-20 CPU-hours (full 3D profile) to 0.5 CPU-hours (simplified 3D profile) to seconds (machine learning). We showed that the simplified profile generation method does not introduce an error with regard to the original method, while increasing the computational efficiency. Our new dataset proved representative enough to use simple statistical methods for testing the amylogenicity based only on six letter sequences. Statistical machine learning methods such as Alternating Decision Tree and Multilayer Perceptron can replace the energy based classifier, with advantage of very significantly reduced computational time and simplicity to perform the analysis. Additionally, a decision tree provides a set of very easily interpretable rules.

Synthesis of Large Quantities of Single-Walled Aluminogermanante Nanotube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levard,C.; Rose, J.; Mision, A.

2008-01-01

A simple aqueous synthesis yielded about 100 times more structurally well-organized single-walled aluminogermanate nanotubes than previously reported 'standard' procedures. The structure analyses using XRD, IRTF, TEM, and XAS were greatly facilitated by the high concentrations available, and they ascertained the imogolite-like structure of the nanotubes. Simplicity and yield of the synthesis protocol are likely to favor commercial applications of theses materials as well as simplified syntheses of other nanophases.

Structure formation in nonlocal MOND

NASA Astrophysics Data System (ADS)

Tan, L.; Woodard, R. P.

2018-05-01

We consider structure formation in a nonlocal, metric-based realization of Milgrom's MOdified Newtonian Dynamics (MOND). We derive the general equations for linearized scalar perturbations about the ΛCDM expansion history. These equations are considerably simplified for sub-horizon modes, and it becomes obvious (in this model) that the MOND enhancement is not sufficient to allow ordinary matter to drive structure formation. We discuss ways in which the model might be changed to correct the problem.

The PEMFC-integrated CO oxidation — a novel method of simplifying the fuel cell plant

NASA Astrophysics Data System (ADS)

Rohland, Bernd; Plzak, Vojtech

Natural gas and methanol are the most economical fuels for residential fuel cell power generators as well as for mobile PEM-fuel cells. However, they have to be reformed with steam into hydrogen, which is to be cleaned from CO by shift-reaction and by partial oxidation to a level of no more than 30 ppm CO. This level is set by the Pt/Ru-C-anode of the PEMFC. A higher partial oxidation reaction rate for CO than those of Pt/Ru-C can be achieved in an oxidic Au-catalyst system. In the Fe 2O 3-Au system, a reaction rate of 2·10 -3 mol CO/s g Au at 1000 ppm CO and 5% "air bleed" at 80°C is achieved. This high rate allows to construct a catalyst-sheet for each cell within a PEMFC-stack. Practical and theoretical current/voltage characteristics of PEMFCs with catalyst-sheet are presented at 1000 ppm CO in hydrogen with 5% "air bleed". This gives the possibility of simplifying the gas processor of the plant.

Approximations to galaxy star formation rate histories: properties and uses of two examples

NASA Astrophysics Data System (ADS)

Cohn, J. D.

2018-05-01

Galaxies evolve via a complex interaction of numerous different physical processes, scales and components. In spite of this, overall trends often appear. Simplified models for galaxy histories can be used to search for and capture such emergent trends, and thus to interpret and compare results of galaxy formation models to each other and to nature. Here, two approximations are applied to galaxy integrated star formation rate histories, drawn from a semi-analytic model grafted onto a dark matter simulation. Both a lognormal functional form and principal component analysis (PCA) approximate the integrated star formation rate histories fairly well. Machine learning, based upon simplified galaxy halo histories, is somewhat successful at recovering both fits. The fits to the histories give fixed time star formation rates which have notable scatter from their true final time rates, especially for quiescent and "green valley" galaxies, and more so for the PCA fit. For classifying galaxies into subfamilies sharing similar integrated histories, both approximations are better than using final stellar mass or specific star formation rate. Several subsamples from the simulation illustrate how these simple parameterizations provide points of contact for comparisons between different galaxy formation samples, or more generally, models. As a side result, the halo masses of simulated galaxies with early peak star formation rate (according to the lognormal fit) are bimodal. The galaxies with a lower halo mass at peak star formation rate appear to stall in their halo growth, even though they are central in their host halos.

The Effects of Forming Parameters on Conical Ring Rolling Process

PubMed Central

Meng, Wen; Zhao, Guoqun; Guan, Yanjin

2014-01-01

The plastic penetration condition and biting-in condition of a radial conical ring rolling process with a closed die structure on the top and bottom of driven roll, simplified as RCRRCDS, were established. The reasonable value range of mandrel feed rate in rolling process was deduced. A coupled thermomechanical 3D FE model of RCRRCDS process was established. The changing laws of equivalent plastic strain (PEEQ) and temperature distributions with rolling time were investigated. The effects of ring's outer radius growth rate and rolls sizes on the uniformities of PEEQ and temperature distributions, average rolling force, and average rolling moment were studied. The results indicate that the PEEQ at the inner layer and outer layer of rolled ring are larger than that at the middle layer of ring; the temperatures at the “obtuse angle zone” of ring's cross-section are higher than those at “acute angle zone”; the temperature at the central part of ring is higher than that at the middle part of ring's outer surfaces. As the ring's outer radius growth rate increases at its reasonable value ranges, the uniformities of PEEQ and temperature distributions increase. Finally, the optimal values of the ring's outer radius growth rate and rolls sizes were obtained. PMID:25202716

Finite element model updating of riveted joints of simplified model aircraft structure

NASA Astrophysics Data System (ADS)

Yunus, M. A.; Rani, M. N. Abdul; Sani, M. S. M.; Shah, M. A. S. Aziz

2018-04-01

Thin metal sheets are widely used to fabricate a various type of aerospace structures because of its flexibility and easily to form into any type shapes of structure. The riveted joint has turn out to be one of the popular joint types in jointing the aerospace structures because they can be easily be disassembled, maintained and inspected. In this paper, thin metal sheet components are assembled together via riveted joints to form a simplified model of aerospace structure. However, to model the jointed structure that are attached together via the mechanical joints such as riveted joint are very difficult due to local effects. Understandably that the dynamic characteristic of the joined structure can be significantly affected by these joints due to local effects at the mating areas of the riveted joints such as surface contact, clamping force and slips. A few types of element connectors that available in MSC NATRAN/PATRAN have investigated in order to presented as the rivet joints. Thus, the results obtained in term of natural frequencies and mode shapes are then contrasted with experimental counterpart in order to investigate the acceptance level of accuracy between element connectors that are used in modelling the rivet joints of the riveted joints structure. The reconciliation method via finiteelement model updating is used to minimise the discrepancy of the initial finite element model of the riveted joined structure as close as experimental data and their results are discussed.

An NMR database for simulations of membrane dynamics.

PubMed

Leftin, Avigdor; Brown, Michael F

2011-03-01

Computational methods are powerful in capturing the results of experimental studies in terms of force fields that both explain and predict biological structures. Validation of molecular simulations requires comparison with experimental data to test and confirm computational predictions. Here we report a comprehensive database of NMR results for membrane phospholipids with interpretations intended to be accessible by non-NMR specialists. Experimental ¹³C-¹H and ²H NMR segmental order parameters (S(CH) or S(CD)) and spin-lattice (Zeeman) relaxation times (T(1Z)) are summarized in convenient tabular form for various saturated, unsaturated, and biological membrane phospholipids. Segmental order parameters give direct information about bilayer structural properties, including the area per lipid and volumetric hydrocarbon thickness. In addition, relaxation rates provide complementary information about molecular dynamics. Particular attention is paid to the magnetic field dependence (frequency dispersion) of the NMR relaxation rates in terms of various simplified power laws. Model-free reduction of the T(1Z) studies in terms of a power-law formalism shows that the relaxation rates for saturated phosphatidylcholines follow a single frequency-dispersive trend within the MHz regime. We show how analytical models can guide the continued development of atomistic and coarse-grained force fields. Our interpretation suggests that lipid diffusion and collective order fluctuations are implicitly governed by the viscoelastic nature of the liquid-crystalline ensemble. Collective bilayer excitations are emergent over mesoscopic length scales that fall between the molecular and bilayer dimensions, and are important for lipid organization and lipid-protein interactions. Future conceptual advances and theoretical reductions will foster understanding of biomembrane structural dynamics through a synergy of NMR measurements and molecular simulations. Copyright © 2010 Elsevier B.V. All rights reserved.

Structural Characteristics and In Vitro Biodegradation of a Novel Zn-Li Alloy Prepared by Induction Melting and Hot Rolling

NASA Astrophysics Data System (ADS)

Zhao, Shan; McNamara, Cameron T.; Bowen, Patrick K.; Verhun, Nicholas; Braykovich, Jacob P.; Goldman, Jeremy; Drelich, Jaroslaw W.

2017-03-01

Zinc shows great promise as a bioabsorbable metal; however, the low tensile strength of pure zinc limits its application for endovascular stent purposes. In this study, a new Zn- xLi alloy (with x = 2, 4, 6 at. pct) was prepared by induction melting in an argon atmosphere and processed through hot rolling. Structures of the formulated binary alloys were characterized by X-ray diffraction and optical microscopy. Mechanical testing showed that the incorporation of Li into Zn increased ultimate tensile strength from <120 MPa (pure Zn) to >560 MPa ( x = 6 at. pct). In vitro corrosion behavior was evaluated by immersion tests in simulated body fluid. The Zn-2Li and Zn-4Li corrosion study demonstrated that corrosion rates and products resemble those observed for pure Zn in vivo, and in addition, the Zn-4Li alloy exhibits higher resistance to corrosion as compared to Zn-2Li. The findings herein encourage further exploration of Zn-Li systems for structural use in biomedical vascular support applications with the ultimate goal of simplifying stent procedures, thereby reducing stent-related complications.

Orthogonal model and experimental data for analyzing wood-fiber-based tri-axial ribbed structural panels in bending

Treesearch

Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

2017-01-01

This paper presents an analysis of 3-dimensional engineered structural panels (3DESP) made from wood-fiber-based laminated paper composites. Since the existing models for calculating the mechanical behavior of core configurations within sandwich panels are very complex, a new simplified orthogonal model (SOM) using an equivalent element has been developed. This model...

A Simplified Method for the 3D Printing of Molecular Models for Chemical Education

ERIC Educational Resources Information Center

Jones, Oliver A. H.; Spencer, Michelle J. S.

2018-01-01

Using tangible models to help students visualize chemical structures in three dimensions has been a mainstay of chemistry education for many years. Conventional chemistry modeling kits are, however, limited in the types and accuracy of the molecules, bonds and structures they can be used to build. The recent development of 3D printing technology…

Analysis and Design of Complex Network Environments

DTIC Science & Technology

2014-02-01

entanglements among un- measured variables. This “potential entanglement ” type of network complexity is previously unaddressed in the literature, yet it...Appreciating the power of structural representations that allow for potential entanglement among unmeasured variables to simplify network inference problems...rely on the idea of subsystems and allows for potential entanglement among unmeasured states. As a result, inferring a system’s signal structure

Process for making carbon foam

DOEpatents

Klett, James W.

2000-01-01

The process obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

Wind-tunnel investigation of the aerodynamic characteristics of the Standard Dynamics Model in coning motion at Mach 0.6

NASA Technical Reports Server (NTRS)

Jermey, C.; Schiff, L. B.

1985-01-01

A series of wind-tunnel tests have been conducted on the Standard Dynamics Model (a simplified generic fighter-aircraft shape) undergoing coning motion at Mach 0.6. Six-component force and moment data are presented for a range of angles of attack, sideslip and coning rates. At the relatively low nondimensional coning rates employed, the lateral aerodynamic charactersitics generally show a linear variation with coning rate.

Laboratory alluvial fans in one dimension.

PubMed

Guerit, L; Métivier, F; Devauchelle, O; Lajeunesse, E; Barrier, L

2014-08-01

When they reach a flat plain, rivers often deposit their sediment load into a cone-shaped structure called alluvial fan. We present a simplified experimental setup that reproduces, in one dimension, basic features of alluvial fans. A mixture of water and glycerol transports and deposits glass beads between two transparent panels separated by a narrow gap. As the beads, which mimic natural sediments, get deposited in this gap, they form an almost one-dimensional fan. At a moderate sediment discharge, the fan grows quasistatically and maintains its slope just above the threshold for sediment transport. The water discharge determines this critical slope. At leading order, the sediment discharge only controls the velocity at which the fan grows. A more detailed analysis reveals a slight curvature of the fan profile, which relates directly to the rate at which sediments are transported.

Effect of thermal processing practices on the properties of superplastic Al-Li alloys

NASA Technical Reports Server (NTRS)

Hales, Stephen J.; Lippard, Henry E.

1993-01-01

The effect of thermal processing on the mechanical properties of superplastically formed structural components fabricated from three aluminum-lithium alloys was evaluated. The starting materials consisted of 8090, 2090, and X2095 (Weldalite(TM) 049), in the form of commercial-grade superplastic sheet. The experimental test matrix was designed to assess the impact on mechanical properties of eliminating solution heat treatment and/or cold water quenching from post-forming thermal processing. The extensive hardness and tensile property data compiled are presented as a function of aging temperature, superplastic strain and temper/quench rate for each alloy. The tensile properties of the materials following superplastic forming in two T5-type tempers are compared with the baseline T6 temper. The implications for simplifying thermal processing without degradation in properties are discussed on the basis of the results.

Computer study the oxygen release from Al melts

NASA Astrophysics Data System (ADS)

Y Galashev, Alexander; Rakhmanova, Oksana R.

2018-02-01

The behavior of oxygen ions in the Al melts under action of a constant electric field was studied by molecular dynamics. The rate of O2- ions moving up from the cathode to the melt surface increases. The time of the first ion reaching the surface decreases with increase in O2- concentration. The Al and O2- self-diffusion coefficients increase with increasing concentration of ions in the system. The structure of the neighborhood of oxygen ions was studied in detail by statistical geometry. The distributions of truncated Voronoi polyhedra according to the number of faces and of faces according to the number of sides were determined. Simplified polyhedra were obtained after elimination of small-scale thermal fluctuations from the model. The picture of the oxygen ions final location can vary greatly depending on the boundary conditions and their application sequence.

Design of an Advanced Wood Composite Rotor and Development of Wood Composite Blade Technology

NASA Technical Reports Server (NTRS)

Stroebel, Thomas; Dechow, Curtis; Zuteck, Michael

1984-01-01

In support of a program to advance wood composite wind turbine blade technology, a design was completed for a prototype, 90-foot diameter, two-bladed, one-piece rotor, with all wood/epoxy composite structure. The rotor was sized for compatibility with a generator having a maximum power rating of 4000 kilowatts. Innovative features of the rotor include: a teetering hub to minimize the effects of gust loads, untwisted blades to promote rotor power control through stall, joining of blades to the hub structure via an adhesive bonded structural joint, and a blade structural design which was simplified relative to earlier efforts. The prototype rotor was designed to allow flexibility for configuring the rotor upwind or downwind of the tower, for evaluating various types of teeter dampers and/or elastomeric stops, and with variable delta-three angle settings of the teeter shaft axis. The prototype rotor was also designed with provisions for installing pressure tap and angle of attack instrumentation in one blade. A production version rotor cost analysis was conducted. Included in the program were efforts directed at developing advanced load take-off stud designs for subsequent evaluation testing by NASA, development of aerodynamic tip brake concepts, exploratory testing of a wood/epoxy/graphite concept, and compression testing of wood/epoxy laminate, with scarf-jointed plies.

Nouvelles techniques pratiques pour la modelisation du comportement dynamique des systèmes eau-structure

NASA Astrophysics Data System (ADS)

Miquel, Benjamin

The dynamic or seismic behavior of hydraulic structures is, as for conventional structures, essential to assure protection of human lives. These types of analyses also aim at limiting structural damage caused by an earthquake to prevent rupture or collapse of the structure. The particularity of these hydraulic structures is that not only the internal displacements are caused by the earthquake, but also by the hydrodynamic loads resulting from fluid-structure interaction. This thesis reviews the existing complex and simplified methods to perform such dynamic analysis for hydraulic structures. For the complex existing methods, attention is placed on the difficulties arising from their use. Particularly, interest is given in this work on the use of transmitting boundary conditions to simulate the semi infinity of reservoirs. A procedure has been developed to estimate the error that these boundary conditions can introduce in finite element dynamic analysis. Depending on their formulation and location, we showed that they can considerably affect the response of such fluid-structure systems. For practical engineering applications, simplified procedures are still needed to evaluate the dynamic behavior of structures in contact with water. A review of the existing simplified procedures showed that these methods are based on numerous simplifications that can affect the prediction of the dynamic behavior of such systems. One of the main objectives of this thesis has been to develop new simplified methods that are more accurate than those existing. First, a new spectral analysis method has been proposed. Expressions for the fundamental frequency of fluid-structure systems, key parameter of spectral analysis, have been developed. We show that this new technique can easily be implemented in a spreadsheet or program, and that its calculation time is near instantaneous. When compared to more complex analytical or numerical method, this new procedure yields excellent prediction of the dynamic behavior of fluid-structure systems. Spectral analyses ignore the transient and oscillatory nature of vibrations. When such dynamic analyses show that some areas of the studied structure undergo excessive stresses, time history analyses allow a better estimate of the extent of these zones as well as a time notion of these excessive stresses. Furthermore, the existing spectral analyses methods for fluid-structure systems account only for the static effect of higher modes. Thought this can generally be sufficient for dams, for flexible structures the dynamic effect of these modes should be accounted for. New methods have been developed for fluid-structure systems to account for these observations as well as the flexibility of foundations. A first method was developed to study structures in contact with one or two finite or infinite water domains. This new technique includes flexibility of structures and foundations as well as the dynamic effect of higher vibration modes and variations of the levels of the water domains. Extension of this method was performed to study beam structures in contact with fluids. These new developments have also allowed extending existing analytical formulations of the dynamic properties of a dry beam to a new formulation that includes effect of fluid-structure interaction. The method yields a very good estimate of the dynamic behavior of beam-fluid systems or beam like structures in contact with fluid. Finally, a Modified Accelerogram Method (MAM) has been developed to modify the design earthquake into a new accelerogram that directly accounts for the effect of fluid-structure interaction. This new accelerogram can therefore be applied directly to the dry structure (i.e. without water) in order to calculate the dynamic response of the fluid-structure system. This original technique can include numerous parameters that influence the dynamic response of such systems and allows to treat analytically the fluid-structure interaction while keeping the advantages of finite element modeling.

A VLSI architecture for simplified arithmetic Fourier transform algorithm

NASA Technical Reports Server (NTRS)

Reed, Irving S.; Shih, Ming-Tang; Truong, T. K.; Hendon, E.; Tufts, D. W.

1992-01-01

The arithmetic Fourier transform (AFT) is a number-theoretic approach to Fourier analysis which has been shown to perform competitively with the classical FFT in terms of accuracy, complexity, and speed. Theorems developed in a previous paper for the AFT algorithm are used here to derive the original AFT algorithm which Bruns found in 1903. This is shown to yield an algorithm of less complexity and of improved performance over certain recent AFT algorithms. A VLSI architecture is suggested for this simplified AFT algorithm. This architecture uses a butterfly structure which reduces the number of additions by 25 percent of that used in the direct method.

Silicon Carbide Metallization

NASA Astrophysics Data System (ADS)

Lescoat, F.; Tanguy, F.; Durand, P.

2016-05-01

A study has been done to assess the feasibility of metallization of Silicon Carbide (SiC) in order to simplify design and mounting of one or more ground reference rail needed to provide an electrical reference for electronics mounted on an SiC structure.

A Unified Kinetics and Equilibrium Experiment: Rate Law, Activation Energy, and Equilibrium Constant for the Dissociation of Ferroin

ERIC Educational Resources Information Center

Sattar, Simeen

2011-01-01

Tris(1,10-phenanthroline)iron(II) is the basis of a suite of four experiments spanning 5 weeks. Students determine the rate law, activation energy, and equilibrium constant for the dissociation of the complex ion in acid solution and base dissociation constant for phenanthroline. The focus on one chemical system simplifies a daunting set of…

Modelling of Heat and Moisture Loss Through NBC Ensembles

DTIC Science & Technology

1991-11-01

the heat and moisture transport through various NBC clothing ensembles. The analysis involves simplifying the three dimensional physical problem of... clothing on a person to that of a one dimensional problem of flow through parallel layers of clothing and air. Body temperatures are calculated based on...prescribed work rates, ambient conditions and clothing properties. Sweat response and respiration rates are estimated based on empirical data to

Motion video analysis using planar parallax

NASA Astrophysics Data System (ADS)

Sawhney, Harpreet S.

1994-04-01

Motion and structure analysis in video sequences can lead to efficient descriptions of objects and their motions. Interesting events in videos can be detected using such an analysis--for instance independent object motion when the camera itself is moving, figure-ground segregation based on the saliency of a structure compared to its surroundings. In this paper we present a method for 3D motion and structure analysis that uses a planar surface in the environment as a reference coordinate system to describe a video sequence. The motion in the video sequence is described as the motion of the reference plane, and the parallax motion of all the non-planar components of the scene. It is shown how this method simplifies the otherwise hard general 3D motion analysis problem. In addition, a natural coordinate system in the environment is used to describe the scene which can simplify motion based segmentation. This work is a part of an ongoing effort in our group towards video annotation and analysis for indexing and retrieval. Results from a demonstration system being developed are presented.

Relative dynamics and motion control of nanosatellite formation flying

NASA Astrophysics Data System (ADS)

Pimnoo, Ammarin; Hiraki, Koju

2016-04-01

Orbit selection is a necessary factor in nanosatellite formation mission design/meanwhile, to keep the formation, it is necessary to consume fuel. Therefore, the best orbit design for nanosatellite formation flying should be one that requires the minimum fuel consumption. The purpose of this paper is to analyse orbit selection with respect to the minimum fuel consumption, to provide a convenient way to estimate the fuel consumption for keeping nanosatellite formation flying and to present a simplified method of formation control. The formation structure is disturbed by J2 gravitational perturbation and other perturbing accelerations such as atmospheric drag. First, Gauss' Variation Equations (GVE) are used to estimate the essential ΔV due to the J2 perturbation and atmospheric drag. The essential ΔV presents information on which orbit is good with respect to the minimum fuel consumption. Then, the linear equations which account for J2 gravitational perturbation of Schweighart-Sedwick are presented and used to estimate the fuel consumption to maintain the formation structure. Finally, the relative dynamics motion is presented as well as a simplified motion control of formation structure by using GVE.

Using a bias aware EnKF to account for unresolved structure in an unsaturated zone model

NASA Astrophysics Data System (ADS)

Erdal, D.; Neuweiler, I.; Wollschläger, U.

2014-01-01

When predicting flow in the unsaturated zone, any method for modeling the flow will have to define how, and to what level, the subsurface structure is resolved. In this paper, we use the Ensemble Kalman Filter to assimilate local soil water content observations from both a synthetic layered lysimeter and a real field experiment in layered soil in an unsaturated water flow model. We investigate the use of colored noise bias corrections to account for unresolved subsurface layering in a homogeneous model and compare this approach with a fully resolved model. In both models, we use a simplified model parameterization in the Ensemble Kalman Filter. The results show that the use of bias corrections can increase the predictive capability of a simplified homogeneous flow model if the bias corrections are applied to the model states. If correct knowledge of the layering structure is available, the fully resolved model performs best. However, if no, or erroneous, layering is used in the model, the use of a homogeneous model with bias corrections can be the better choice for modeling the behavior of the system.

Crack cause analysis of a graphite nozzle throat insert

NASA Astrophysics Data System (ADS)

Sun, Lin; Bao, Futing; Zhao, Yu; Hou, Lian; Hui, Weihua; Zhang, Ning; Shi, Wei

2017-08-01

With an objective to determine the failure cause of a throughout crack at an angle of 45° and a breach during a firing test, a simplified analysis procedure with consideration of the structure gap was established to simulate the thermo-structural response of a nozzle. By neglecting erosion and pyrolysis of the insulating materials and establishing temperature-dependent or anisotropic material models, ANSYS Parameter Design Language codes were written to perform the fully coupled thermal-structural simulation. A Quasi-1D flow was calculated for supplying boundary conditions. Study on mesh independence and time step independence was also conducted to evaluate simulated results. It was found that shortly after ignition, compressive stress in the x direction and tensile stress in the y direction contributed to anomalies. And through contact status analysis, inappropriate gap design was regarded as the origin of the too large stress, which was the primary cause of these anomalies during firing test. Simulation results were in good agreement with firing test results. In addition, the simplified analysis procedure was proven effective. Gap size should be seriously dealt with in the future design.

Intrinsically-generated fluctuating activity in excitatory-inhibitory networks.

PubMed

Mastrogiuseppe, Francesca; Ostojic, Srdjan

2017-04-01

Recurrent networks of non-linear units display a variety of dynamical regimes depending on the structure of their synaptic connectivity. A particularly remarkable phenomenon is the appearance of strongly fluctuating, chaotic activity in networks of deterministic, but randomly connected rate units. How this type of intrinsically generated fluctuations appears in more realistic networks of spiking neurons has been a long standing question. To ease the comparison between rate and spiking networks, recent works investigated the dynamical regimes of randomly-connected rate networks with segregated excitatory and inhibitory populations, and firing rates constrained to be positive. These works derived general dynamical mean field (DMF) equations describing the fluctuating dynamics, but solved these equations only in the case of purely inhibitory networks. Using a simplified excitatory-inhibitory architecture in which DMF equations are more easily tractable, here we show that the presence of excitation qualitatively modifies the fluctuating activity compared to purely inhibitory networks. In presence of excitation, intrinsically generated fluctuations induce a strong increase in mean firing rates, a phenomenon that is much weaker in purely inhibitory networks. Excitation moreover induces two different fluctuating regimes: for moderate overall coupling, recurrent inhibition is sufficient to stabilize fluctuations; for strong coupling, firing rates are stabilized solely by the upper bound imposed on activity, even if inhibition is stronger than excitation. These results extend to more general network architectures, and to rate networks receiving noisy inputs mimicking spiking activity. Finally, we show that signatures of the second dynamical regime appear in networks of integrate-and-fire neurons.

Intrinsically-generated fluctuating activity in excitatory-inhibitory networks

PubMed Central

Mastrogiuseppe, Francesca; Ostojic, Srdjan

2017-01-01

Recurrent networks of non-linear units display a variety of dynamical regimes depending on the structure of their synaptic connectivity. A particularly remarkable phenomenon is the appearance of strongly fluctuating, chaotic activity in networks of deterministic, but randomly connected rate units. How this type of intrinsically generated fluctuations appears in more realistic networks of spiking neurons has been a long standing question. To ease the comparison between rate and spiking networks, recent works investigated the dynamical regimes of randomly-connected rate networks with segregated excitatory and inhibitory populations, and firing rates constrained to be positive. These works derived general dynamical mean field (DMF) equations describing the fluctuating dynamics, but solved these equations only in the case of purely inhibitory networks. Using a simplified excitatory-inhibitory architecture in which DMF equations are more easily tractable, here we show that the presence of excitation qualitatively modifies the fluctuating activity compared to purely inhibitory networks. In presence of excitation, intrinsically generated fluctuations induce a strong increase in mean firing rates, a phenomenon that is much weaker in purely inhibitory networks. Excitation moreover induces two different fluctuating regimes: for moderate overall coupling, recurrent inhibition is sufficient to stabilize fluctuations; for strong coupling, firing rates are stabilized solely by the upper bound imposed on activity, even if inhibition is stronger than excitation. These results extend to more general network architectures, and to rate networks receiving noisy inputs mimicking spiking activity. Finally, we show that signatures of the second dynamical regime appear in networks of integrate-and-fire neurons. PMID:28437436

Innovative Design for Composite Spacecraft Structure Thanks to Automatic Fiber Placement Technology

NASA Astrophysics Data System (ADS)

Brindeau, Aymeric; Khalfi, Thomas

2014-06-01

The innovative design for composite spacecraft structure thanks to automatic fiber placement technology takes place in the frame of the development of a new launcher. A heavy loaded spacecraft carrying structure is developed in order to allow performance and big payload volumes.This kind of structure already exists on a current launcher, but performances are not compatible with the new requirements. Indeed, in spite of a sandwich design made of carbon and aluminium honeycomb, mass and stiffness requirements are not fulfilled.Consequently, for the new structure, an innovative design has been set-up. The materials are still sandwich made of carbon and aluminium honeycomb in order to obtain the best ratio mass / stiffness, but major evolutions have been implemented of the geometry of the structure in order to increase the performance of the product. These evolutions are allowed thanks to the use of the fiber placement technology, which allows manufacturing geometries that are not reachable with standard lay-up by hands. The main progress deals with the manufacturing of revolution sub-structures, in one shot, with double curvature areas. Moreover, beyond the technical performance of the new product and the gains in terms of manufacturing time and quality, the integration of sub-structures is extremely simplified compared to the existing process. As a result, the technology of fiber placement is the opportunity to imagine new designs which allows increasing the performances, to reduce manufacturing cycles, and to simplify integration operations.

Detection of grapes in natural environment using HOG features in low resolution images

NASA Astrophysics Data System (ADS)

Škrabánek, Pavel; Majerík, Filip

2017-07-01

Detection of grapes in real-life images has importance in various viticulture applications. A grape detector based on an SVM classifier, in combination with a HOG descriptor, has proven to be very efficient in detection of white varieties in high-resolution images. Nevertheless, the high time complexity of such utilization was not suitable for its real-time applications, even when a detector of a simplified structure was used. Thus, we examined possibilities of the simplified version application on images of lower resolutions. For this purpose, we designed a method aimed at search for a detector’s setting which gives the best time complexity vs. performance ratio. In order to provide precise evaluation results, we formed new extended datasets. We discovered that even applied on low-resolution images, the simplified detector, with an appropriate setting of all tuneable parameters, was competitive with other state of the art solutions. We concluded that the detector is qualified for real-time detection of grapes in real-life images.

On equivalent parameter learning in simplified feature space based on Bayesian asymptotic analysis.

PubMed

Yamazaki, Keisuke

2012-07-01

Parametric models for sequential data, such as hidden Markov models, stochastic context-free grammars, and linear dynamical systems, are widely used in time-series analysis and structural data analysis. Computation of the likelihood function is one of primary considerations in many learning methods. Iterative calculation of the likelihood such as the model selection is still time-consuming though there are effective algorithms based on dynamic programming. The present paper studies parameter learning in a simplified feature space to reduce the computational cost. Simplifying data is a common technique seen in feature selection and dimension reduction though an oversimplified space causes adverse learning results. Therefore, we mathematically investigate a condition of the feature map to have an asymptotically equivalent convergence point of estimated parameters, referred to as the vicarious map. As a demonstration to find vicarious maps, we consider the feature space, which limits the length of data, and derive a necessary length for parameter learning in hidden Markov models. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Role of Surface, Semantic and Grammatical Features on Simplification of Spanish Medical Texts: A User Study

PubMed Central

Mukherjee, Partha; Leroy, Gondy; Kauchak, David; Navarrete, Brianda Armenta; Diaz, Damian Y.; Colina, Sonia

2017-01-01

Simplifying medical texts facilitates readability and comprehension. While most simplification work focuses on English, we investigate whether features important for simplifying English text are similarly helpful for simplifying Spanish text. We conducted a user study on 15 Spanish medical texts using Amazon Mechanical Turk and measured perceived and actual difficulty. Using the median of the difficulty scores, we split the texts into easy and difficult groups and extracted 10 surface, 2 semantic and 4 grammatical features. Using t-tests, we identified those features that significantly distinguish easy text from difficult text in Spanish and compare with prior work in English. We found that easy Spanish texts use more repeated words and adverbs, less negations and more familiar words, similar to English. Also like English, difficult Spanish texts use more nouns and adjectives. However in contrast to English, easier Spanish texts contained longer sentences and used grammatical structures that were more varied. PMID:29854201

Analysis of simplified heat transfer models for thermal property determination of nano-film by TDTR method

NASA Astrophysics Data System (ADS)

Wang, Xinwei; Chen, Zhe; Sun, Fangyuan; Zhang, Hang; Jiang, Yuyan; Tang, Dawei

2018-03-01

Heat transfer in nanostructures is of critical importance for a wide range of applications such as functional materials and thermal management of electronics. Time-domain thermoreflectance (TDTR) has been proved to be a reliable measurement technique for the thermal property determinations of nanoscale structures. However, it is difficult to determine more than three thermal properties at the same time. Heat transfer model simplifications can reduce the fitting variables and provide an alternative way for thermal property determination. In this paper, two simplified models are investigated and analyzed by the transform matrix method and simulations. TDTR measurements are performed on Al-SiO2-Si samples with different SiO2 thickness. Both theoretical and experimental results show that the simplified tri-layer model (STM) is reliable and suitable for thin film samples with a wide range of thickness. Furthermore, the STM can also extract the intrinsic thermal conductivity and interfacial thermal resistance from serial samples with different thickness.

Predator-prey Encounter Rates in Turbulent Environments: Consequences of Inertia Effects and Finite Sizes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pecseli, H. L.; Trulsen, J.

2009-10-08

Experimental as well as theoretical studies have demonstrated that turbulence can play an important role for the biosphere in marine environments, in particular also by affecting prey-predator encounter rates. Reference models for the encounter rates rely on simplifying assumptions of predators and prey being described as point particles moving passively with the local flow velocity. Based on simple arguments that can be tested experimentally we propose corrections for the standard expression for the encounter rates, where now finite sizes and Stokes drag effects are included.

Maximum-Likelihood Detection Of Noncoherent CPM

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Simon, Marvin K.

1993-01-01

Simplified detectors proposed for use in maximum-likelihood-sequence detection of symbols in alphabet of size M transmitted by uncoded, full-response continuous phase modulation over radio channel with additive white Gaussian noise. Structures of receivers derived from particular interpretation of maximum-likelihood metrics. Receivers include front ends, structures of which depends only on M, analogous to those in receivers of coherent CPM. Parts of receivers following front ends have structures, complexity of which would depend on N.

Models of earth structure inferred from neodymium and strontium isotopic abundances

PubMed Central

Wasserburg, G. J.; DePaolo, D. J.

1979-01-01

A simplified model of earth structure based on the Nd and Sr isotopic characteristics of oceanic and continental tholeiitic flood basalts is presented, taking into account the motion of crustal plates and a chemical balance for trace elements. The resulting structure that is inferred consists of a lower mantle that is still essentially undifferentiated, overlain by an upper mantle that is the residue of the original source from which the continents were derived. PMID:16592688

Fault Diagnostics for Turbo-Shaft Engine Sensors Based on a Simplified On-Board Model

PubMed Central

Lu, Feng; Huang, Jinquan; Xing, Yaodong

2012-01-01

Combining a simplified on-board turbo-shaft model with sensor fault diagnostic logic, a model-based sensor fault diagnosis method is proposed. The existing fault diagnosis method for turbo-shaft engine key sensors is mainly based on a double redundancies technique, and this can't be satisfied in some occasions as lack of judgment. The simplified on-board model provides the analytical third channel against which the dual channel measurements are compared, while the hardware redundancy will increase the structure complexity and weight. The simplified turbo-shaft model contains the gas generator model and the power turbine model with loads, this is built up via dynamic parameters method. Sensor fault detection, diagnosis (FDD) logic is designed, and two types of sensor failures, such as the step faults and the drift faults, are simulated. When the discrepancy among the triplex channels exceeds a tolerance level, the fault diagnosis logic determines the cause of the difference. Through this approach, the sensor fault diagnosis system achieves the objectives of anomaly detection, sensor fault diagnosis and redundancy recovery. Finally, experiments on this method are carried out on a turbo-shaft engine, and two types of faults under different channel combinations are presented. The experimental results show that the proposed method for sensor fault diagnostics is efficient. PMID:23112645

Fault diagnostics for turbo-shaft engine sensors based on a simplified on-board model.

PubMed

Lu, Feng; Huang, Jinquan; Xing, Yaodong

2012-01-01

Combining a simplified on-board turbo-shaft model with sensor fault diagnostic logic, a model-based sensor fault diagnosis method is proposed. The existing fault diagnosis method for turbo-shaft engine key sensors is mainly based on a double redundancies technique, and this can't be satisfied in some occasions as lack of judgment. The simplified on-board model provides the analytical third channel against which the dual channel measurements are compared, while the hardware redundancy will increase the structure complexity and weight. The simplified turbo-shaft model contains the gas generator model and the power turbine model with loads, this is built up via dynamic parameters method. Sensor fault detection, diagnosis (FDD) logic is designed, and two types of sensor failures, such as the step faults and the drift faults, are simulated. When the discrepancy among the triplex channels exceeds a tolerance level, the fault diagnosis logic determines the cause of the difference. Through this approach, the sensor fault diagnosis system achieves the objectives of anomaly detection, sensor fault diagnosis and redundancy recovery. Finally, experiments on this method are carried out on a turbo-shaft engine, and two types of faults under different channel combinations are presented. The experimental results show that the proposed method for sensor fault diagnostics is efficient.

Sampling considerations for modal analysis with damping

NASA Astrophysics Data System (ADS)

Park, Jae Young; Wakin, Michael B.; Gilbert, Anna C.

2015-03-01

Structural health monitoring (SHM) systems are critical for monitoring aging infrastructure (such as buildings or bridges) in a cost-effective manner. Wireless sensor networks that sample vibration data over time are particularly appealing for SHM applications due to their flexibility and low cost. However, in order to extend the battery life of wireless sensor nodes, it is essential to minimize the amount of vibration data these sensors must collect and transmit. In recent work, we have studied the performance of the Singular Value Decomposition (SVD) applied to the collection of data and provided new finite sample analysis characterizing conditions under which this simple technique{also known as the Proper Orthogonal Decomposition (POD){can correctly estimate the mode shapes of the structure. Specifically, we provided theoretical guarantees on the number and duration of samples required in order to estimate a structure's mode shapes to a desired level of accuracy. In that previous work, however, we considered simplified Multiple-Degree-Of-Freedom (MDOF) systems with no damping. In this paper we consider MDOF systems with proportional damping and show that, with sufficiently light damping, the POD can continue to provide accurate estimates of a structure's mode shapes. We support our discussion with new analytical insight and experimental demonstrations. In particular, we study the tradeoffs between the level of damping, the sampling rate and duration, and the accuracy to which the structure's mode shapes can be estimated.

Aerodynamic characteristics of the standard dynamics model in coning motion at Mach 0.6

NASA Technical Reports Server (NTRS)

Jermey, C.; Schiff, L. B.

1985-01-01

A wind tunnel test was conducted on the Standard Dynamics Model (a simplified generic fighter aircraft shape) undergoing coning motion at Mach 0.6. Six component force and moment data are presented for a range of angle of attack, sideslip, and coning rates. At the relatively low non-dimensional coning rate employed (omega b/2V less than or equal to 0.04), the lateral aerodynamic characteristics generally show a linear variation with coning rate.

Advancements in dynamic kill calculations for blowout wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kouba, G.E.; MacDougall, G.R.; Schumacher, B.W.

1993-09-01

This paper addresses the development, interpretation, and use of dynamic kill equations. To this end, three simple calculation techniques are developed for determining the minimum dynamic kill rate. Two techniques contain only single-phase calculations and are independent of reservoir inflow performance. Despite these limitations, these two methods are useful for bracketing the minimum flow rates necessary to kill a blowing well. For the third technique, a simplified mechanistic multiphase-flow model is used to determine a most-probable minimum kill rate.

Mapping DNA methylation by transverse current sequencing: Reduction of noise from neighboring nucleotides

NASA Astrophysics Data System (ADS)

Alvarez, Jose; Massey, Steven; Kalitsov, Alan; Velev, Julian

Nanopore sequencing via transverse current has emerged as a competitive candidate for mapping DNA methylation without needed bisulfite-treatment, fluorescent tag, or PCR amplification. By eliminating the error producing amplification step, long read lengths become feasible, which greatly simplifies the assembly process and reduces the time and the cost inherent in current technologies. However, due to the large error rates of nanopore sequencing, single base resolution has not been reached. A very important source of noise is the intrinsic structural noise in the electric signature of the nucleotide arising from the influence of neighboring nucleotides. In this work we perform calculations of the tunneling current through DNA molecules in nanopores using the non-equilibrium electron transport method within an effective multi-orbital tight-binding model derived from first-principles calculations. We develop a base-calling algorithm accounting for the correlations of the current through neighboring bases, which in principle can reduce the error rate below any desired precision. Using this method we show that we can clearly distinguish DNA methylation and other base modifications based on the reading of the tunneling current.

Nonlinear convergence active vibration absorber for single and multiple frequency vibration control

NASA Astrophysics Data System (ADS)

Wang, Xi; Yang, Bintang; Guo, Shufeng; Zhao, Wenqiang

2017-12-01

This paper presents a nonlinear convergence algorithm for active dynamic undamped vibration absorber (ADUVA). The damping of absorber is ignored in this algorithm to strengthen the vibration suppressing effect and simplify the algorithm at the same time. The simulation and experimental results indicate that this nonlinear convergence ADUVA can help significantly suppress vibration caused by excitation of both single and multiple frequency. The proposed nonlinear algorithm is composed of equivalent dynamic modeling equations and frequency estimator. Both the single and multiple frequency ADUVA are mathematically imitated by the same mechanical structure with a mass body and a voice coil motor (VCM). The nonlinear convergence estimator is applied to simultaneously satisfy the requirements of fast convergence rate and small steady state frequency error, which are incompatible for linear convergence estimator. The convergence of the nonlinear algorithm is mathematically proofed, and its non-divergent characteristic is theoretically guaranteed. The vibration suppressing experiments demonstrate that the nonlinear ADUVA can accelerate the convergence rate of vibration suppressing and achieve more decrement of oscillation attenuation than the linear ADUVA.

AUTOMATIC ENGLISH-TO-LOGIC TRANSLATION IN A SIMPLIFIED MODEL, A STUDY IN THE LOGIC OF GRAMMAR. FINAL REPORT.

ERIC Educational Resources Information Center

BACKER, P.O.; BOHNERT, H.G.

THE LATEST IN A SERIES OF ENGLISH-LIKE LANGUAGES IS DESCRIBED WHICH IS TRANSLATABLE INTO FORMS OF A FIRST-ORDER PREDICATE CALCULUS NOTATION. THE STUDY IS BASED ON THE HYPOTHESIS THAT SYNTACTIC AMBIGUITY ARISING FROM DIFFERENCES IN DEEP STRUCTURE CAN BE ADEQUATELY DESCRIBED ONLY IF THE DEEP STRUCTURES CAN BE SYSTEMATICALLY REPRESENTED. THE NOTATION…

Design for inadvertent damage in composite laminates

NASA Technical Reports Server (NTRS)

Singhal, Surendra N.; Chamis, Christos C.

1992-01-01

Simplified predictive methods and models to computationally simulate durability and damage in polymer matrix composite materials/structures are described. The models include (1) progressive fracture, (2) progressively damaged structural behavior, (3) progressive fracture in aggressive environments, (4) stress concentrations, and (5) impact resistance. Several examples are included to illustrate applications of the models and to identify significant parameters and sensitivities. Comparisons with limited experimental data are made.

Sintering Process and Mechanical Property of MWCNTs/HDPE Bulk Composite

PubMed Central

Tze-Chi, Hsu; Jie-Ren, Zheng

2009-01-01

Studies have proved that increasing polymer matrices by carbon nanotubes to form structural reinforcement and electrical conductivity have significantly improved mechanical and electrical properties at very low carbon nanotubes loading. In other words, increasing polymer matrices by carbon nanotubes to form structural reinforcement can reduce friction coefficient and enhance anti-wear property. However, producing traditional MWCNTs in polymeric materix is an extremely complicated process. Using melt-mixing process or in situ polymerization leads to better dispersion effect on composite materials. In this study, therefore, to simplify MWCNTs /HDPE composite process and increase dispersion, powder was used directly to replace pellet to mix and sinter with MWCNTs. The composite bulks with 0, 0.5, 1, 2 and 4% nanotube content by weight was analyzed under SEM to observe nanotubes dispersion. At this rate, a MWCNTs/HDPE composite bulk with uniformly dispersed MWCNTs was achieved, and through the wear bench (Pin-on-Disk), the wear experiment has accomplished. Accordingly, the result suggests the sintered MWCNTs/HDPE composites amplify the hardness and wear-resist property. PMID:19730688

Endowing Hydrochromism to Fluorans via Bioinspired Alteration of Molecular Structures and Microenvironments and Expanding Their Potential for Rewritable Paper.

PubMed

Xi, Guan; Sheng, Lan; Zhang, Ivan; Du, Jiahui; Zhang, Ting; Chen, Qiaonan; Li, Guiying; Zhang, Ying; Song, Yue; Li, Jianhua; Zhang, Yu-Mo; Zhang, Sean Xiao-An

2017-11-01

Interest and effort toward new materials for rewritable paper have increased dramatically because of the exciting advantages for sustainable development and better nature life cycle. Inspired by how nature works within living systems, herein, we have used fluorans, as a concept verification, to endow original acidochromic, basochromic or photochromic molecules with broader properties, such as switchable with solvent, water, heat, electricity, stress, other force, etc., via simplified methods (i.e., via variation of submolecular structure or microenvironments). The hydrochromic visual change and reversible behavior of selected molecules have been explored, and the primary mechanism at the atomic or subatomic level has been hypothesized. In addition, several newly demonstrated hydrochromic fluorans have been utilized for water-jet rewritable paper (WJRP), which exhibit great photostability, high hydrochromic contrast, and fast responsive rate and which can be reused at least 30 times without significant variation. The water-jet prints have good resolution and various colors and can keep legibility after a few months or years. This improved performance is a major step toward practical applications of WJRP.

Artificial cell mimics as simplified models for the study of cell biology.

PubMed

Salehi-Reyhani, Ali; Ces, Oscar; Elani, Yuval

2017-07-01

Living cells are hugely complex chemical systems composed of a milieu of distinct chemical species (including DNA, proteins, lipids, and metabolites) interconnected with one another through a vast web of interactions: this complexity renders the study of cell biology in a quantitative and systematic manner a difficult task. There has been an increasing drive towards the utilization of artificial cells as cell mimics to alleviate this, a development that has been aided by recent advances in artificial cell construction. Cell mimics are simplified cell-like structures, composed from the bottom-up with precisely defined and tunable compositions. They allow specific facets of cell biology to be studied in isolation, in a simplified environment where control of variables can be achieved without interference from a living and responsive cell. This mini-review outlines the core principles of this approach and surveys recent key investigations that use cell mimics to address a wide range of biological questions. It will also place the field in the context of emerging trends, discuss the associated limitations, and outline future directions of the field. Impact statement Recent years have seen an increasing drive to construct cell mimics and use them as simplified experimental models to replicate and understand biological phenomena in a well-defined and controlled system. By summarizing the advances in this burgeoning field, and using case studies as a basis for discussion on the limitations and future directions of this approach, it is hoped that this minireview will spur others in the experimental biology community to use artificial cells as simplified models with which to probe biological systems.

Intentionality, degree of damage, and moral judgments.

PubMed

Berg-Cross, L G

1975-12-01

153 first graders were given Piagetian moral judgment problems with a new simplified methodology as well as the usual story-pair paradigm. The new methodology involved making quantitative judgments about single stories and examined the influence of level of intentionality and degree of damage upon absolute punishment ratings. Contrary to results obtained with a story-pair methodology, it was found that with single stories even 6-year-old children responded to the level of intention in the stories as well as the quantity and quality of damage involved. This suggested that Piaget's methodology may be forcing children to employ a simplifying strategy while under other conditions they are able to perform the mental operations necessary to make complex moral judgments.

Estimating surface temperature in forced convection nucleate boiling - A simplified method

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Papell, S. S.

1977-01-01

A simplified expression to estimate surface temperatures in forced convection boiling was developed using a liquid nitrogen data base. Using the principal of corresponding states and the Kutateladze relation for maximum pool boiling heat flux, the expression was normalized for use with other fluids. The expression was applied also to neon and water. For the neon data base, the agreement was acceptable with the exclusion of one set suspected to be in the transition boiling regime. For the water data base at reduced pressure greater than 0.05 the agreement is generally good. At lower reduced pressures, the water data scatter and the calculated temperature becomes a function of flow rate.

Experimental investigation on the flow around a simplified geometry of automotive engine compartment

NASA Astrophysics Data System (ADS)

D'Hondt, Marion; Gilliéron, Patrick; Devinant, Philippe

2011-05-01

In the current sustainable development context, car manufacturers have to keep doing efforts to reduce the aerodynamic drag of automotive vehicle in order to decrease their CO2 and greenhouse gas emissions. The cooling airflow, through the engine compartment of vehicles, contributes from 5 to 10% to the total aerodynamic drag. By means of simplified car geometry, equipped with an engine compartment, the configurations that favor a low contribution to total drag are identified. PIV (particle image velocimetry) velocity measurements in the wake of the geometry allow explaining these drag reductions. Besides, the cooling flow rate is also assessed and gives indications on the configurations that favor the engine cooling.

Geocoded data structures and their applications to Earth science investigations

NASA Technical Reports Server (NTRS)

Goldberg, M.

1984-01-01

A geocoded data structure is a means for digitally representing a geographically referenced map or image. The characteristics of representative cellular, linked, and hybrid geocoded data structures are reviewed. The data processing requirements of Earth science projects at the Goddard Space Flight Center and the basic tools of geographic data processing are described. Specific ways that new geocoded data structures can be used to adapt these tools to scientists' needs are presented. These include: expanding analysis and modeling capabilities; simplifying the merging of data sets from diverse sources; and saving computer storage space.

Simple and high-speed polarization-based QKD

NASA Astrophysics Data System (ADS)

Grünenfelder, Fadri; Boaron, Alberto; Rusca, Davide; Martin, Anthony; Zbinden, Hugo

2018-01-01

We present a simplified BB84 protocol with only three quantum states and one decoy-state level. We implement this scheme using the polarization degree of freedom at telecom wavelength. Only one pulsed laser is used in order to reduce possible side-channel attacks. The repetition rate of 625 MHz and the achieved secret bit rate of 23 bps over 200 km of standard fiber are the actual state of the art.

Latrunculin A can improve the birth rate of cloned mice and simplify the nuclear transfer protocol by gently inhibiting actin polymerization.

PubMed

Terashita, Yukari; Wakayama, Sayaka; Yamagata, Kazuo; Li, Chong; Sato, Eimei; Wakayama, Teruhiko

2012-06-01

Although animal cloning is becoming more practicable, there are many abnormalities in cloned embryos, and the success rate of producing live animals by cloning has been low. Here, we focused on the procedure for preventing pseudo-second polar body extrusion from somatic cell nuclear transfer (SCNT)-derived oocytes. Typically, reconstructed oocytes are treated with cytochalasin B (CB), but here latrunculin A (LatA) was used instead of CB to prevent pseudo-second polar body extrusion by inhibiting actin polymerization. CB caps F-actin, LatA binds G-actin, and both drugs prevent their polymerization. When the localization of F-actin was examined using phalloidin staining, it was abnormally scattered in the cytoplasm of CB-treated 1-cell embryos, but this was not detected in LatA-treated or in vitro fertilization-derived control embryos. The spindle was larger in CB-treated oocytes than in LatA-treated or untreated control oocytes. LatA treatment also doubled the rate of full-term development after embryo transfer. These results suggest that cloning efficiency in mice can be improved by optimizing each step of the SCNT procedure. Moreover, by using LatA, we could simplify the procedure with a higher birth rate of cloned mice compared with our original method.

Quantitative chemical exchange saturation transfer (qCEST) MRI - omega plot analysis of RF-spillover-corrected inverse CEST ratio asymmetry for simultaneous determination of labile proton ratio and exchange rate.

PubMed

Wu, Renhua; Xiao, Gang; Zhou, Iris Yuwen; Ran, Chongzhao; Sun, Phillip Zhe

2015-03-01

Chemical exchange saturation transfer (CEST) MRI is sensitive to labile proton concentration and exchange rate, thus allowing measurement of dilute CEST agent and microenvironmental properties. However, CEST measurement depends not only on the CEST agent properties but also on the experimental conditions. Quantitative CEST (qCEST) analysis has been proposed to address the limitation of the commonly used simplistic CEST-weighted calculation. Recent research has shown that the concomitant direct RF saturation (spillover) effect can be corrected using an inverse CEST ratio calculation. We postulated that a simplified qCEST analysis is feasible with omega plot analysis of the inverse CEST asymmetry calculation. Specifically, simulations showed that the numerically derived labile proton ratio and exchange rate were in good agreement with input values. In addition, the qCEST analysis was confirmed experimentally in a phantom with concurrent variation in CEST agent concentration and pH. Also, we demonstrated that the derived labile proton ratio increased linearly with creatine concentration (P < 0.01) while the pH-dependent exchange rate followed a dominantly base-catalyzed exchange relationship (P < 0.01). In summary, our study verified that a simplified qCEST analysis can simultaneously determine labile proton ratio and exchange rate in a relatively complex in vitro CEST system. Copyright © 2015 John Wiley & Sons, Ltd.

Medicare and Medicaid programs; CY 2015 Home Health Prospective Payment System rate update; Home Health Quality Reporting Requirements; and survey and enforcement requirements for home health agencies. Final rule.

PubMed

2014-11-06

This final rule updates Home Health Prospective Payment System (HH PPS) rates, including the national, standardized 60-day episode payment rates, the national per-visit rates, and the non-routine medical supply (NRS) conversion factor under the Medicare prospective payment system for home health agencies (HHAs), effective for episodes ending on or after January 1, 2015. As required by the Affordable Care Act, this rule implements the second year of the four-year phase-in of the rebasing adjustments to the HH PPS payment rates. This rule provides information on our efforts to monitor the potential impacts of the rebasing adjustments and the Affordable Care Act mandated face-to-face encounter requirement. This rule also implements: Changes to simplify the face-to-face encounter regulatory requirements; changes to the HH PPS case-mix weights; changes to the home health quality reporting program requirements; changes to simplify the therapy reassessment timeframes; a revision to the Speech-Language Pathology (SLP) personnel qualifications; minor technical regulations text changes; and limitations on the reviewability of the civil monetary penalty provisions. Finally, this rule also discusses Medicare coverage of insulin injections under the HH PPS, the delay in the implementation of the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM), and a HH value-based purchasing (HH VBP) model.

Role of gravity in preparative electrophoresis

NASA Technical Reports Server (NTRS)

Bier, M.

1975-01-01

The fundamental formulas of electrophoresis are derived microscopically and applied to the problem of isotachophoresis. A simple physical model of the isotachophoresis front is proposed. The front motion and structure are studied in the simplified case without convection, diffusion and non-electric external forces.

A Simplified Representation of the Chemical Nature and Reactions of Soil Humus.

ERIC Educational Resources Information Center

Stevenson, F. J.; Olsen, R. A.

1989-01-01

Presented is a comprehensible structural representation of humic substances. A number of important roles of soil organic matter, including contribution to the cation-exchange capacity, binding of pesticides, and formation of complexes with micronutrient cations, are illustrated. (Author/CW)

49 CFR 1111.2 - Amended and supplemental complaints.

Code of Federal Regulations, 2010 CFR

2010-10-01

... TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION RULES OF PRACTICE COMPLAINT AND INVESTIGATION PROCEDURES... evidence to opt for a different rate reasonableness methodology, among Three-Benchmark, Simplified-SAC or Full-SAC. If so amended, the procedural schedule begins again under the new methodology as set forth at...

Planar doped barrier devices for subharmonic mixers

NASA Technical Reports Server (NTRS)

Lee, T. H.; East, J. R.; Haddad, G. I.

1991-01-01

An overview is given of planar doped barrier (PDB) devices for subharmonic mixer applications. A simplified description is given of PDB characteristics along with a more complete numerical analysis of the current versus voltage characteristics of typical structures. The analysis points out the tradeoffs between the device structure and the resulting characteristics that are important for mixer performance. Preliminary low-frequency characterization results are given for the device structures, and a computer analysis of subharmonic mixer parameters and performance is presented.

Image acquisition system using on sensor compressed sampling technique

NASA Astrophysics Data System (ADS)

Gupta, Pravir Singh; Choi, Gwan Seong

2018-01-01

Advances in CMOS technology have made high-resolution image sensors possible. These image sensors pose significant challenges in terms of the amount of raw data generated, energy efficiency, and frame rate. This paper presents a design methodology for an imaging system and a simplified image sensor pixel design to be used in the system so that the compressed sensing (CS) technique can be implemented easily at the sensor level. This results in significant energy savings as it not only cuts the raw data rate but also reduces transistor count per pixel; decreases pixel size; increases fill factor; simplifies analog-to-digital converter, JPEG encoder, and JPEG decoder design; decreases wiring; and reduces the decoder size by half. Thus, CS has the potential to increase the resolution of image sensors for a given technology and die size while significantly decreasing the power consumption and design complexity. We show that it has potential to reduce power consumption by about 23% to 65%.

Equivalent circuit-level model of quantum cascade lasers with integrated hot-electron and hot-phonon effects

NASA Astrophysics Data System (ADS)

Yousefvand, H. R.

2017-12-01

We report a study of the effects of hot-electron and hot-phonon dynamics on the output characteristics of quantum cascade lasers (QCLs) using an equivalent circuit-level model. The model is developed from the energy balance equation to adopt the electron temperature in the active region levels, the heat transfer equation to include the lattice temperature, the nonequilibrium phonon rate to account for the hot phonon dynamics and simplified two-level rate equations to incorporate the carrier and photon dynamics in the active region. This technique simplifies the description of the electron-phonon interaction in QCLs far from the equilibrium condition. Using the presented model, the steady and transient responses of the QCLs for a wide range of sink temperatures (80 to 320 K) are investigated and analysed. The model enables us to explain the operating characteristics found in QCLs. This predictive model is expected to be applicable to all QCL material systems operating in pulsed and cw regimes.

Biped Robot Gait Planning Based on 3D Linear Inverted Pendulum Model

NASA Astrophysics Data System (ADS)

Yu, Guochen; Zhang, Jiapeng; Bo, Wu

2018-01-01

In order to optimize the biped robot’s gait, the biped robot’s walking motion is simplify to the 3D linear inverted pendulum motion mode. The Center of Mass (CoM) locus is determined from the relationship between CoM and the Zero Moment Point (ZMP) locus. The ZMP locus is planned in advance. Then, the forward gait and lateral gait are simplified as connecting rod structure. Swing leg trajectory using B-spline interpolation. And the stability of the walking process is discussed in conjunction with the ZMP equation. Finally the system simulation is carried out under the given conditions to verify the validity of the proposed planning method.

Further investigation on "A multiplicative regularization for force reconstruction"

NASA Astrophysics Data System (ADS)

Aucejo, M.; De Smet, O.

2018-05-01

We have recently proposed a multiplicative regularization to reconstruct mechanical forces acting on a structure from vibration measurements. This method does not require any selection procedure for choosing the regularization parameter, since the amount of regularization is automatically adjusted throughout an iterative resolution process. The proposed iterative algorithm has been developed with performance and efficiency in mind, but it is actually a simplified version of a full iterative procedure not described in the original paper. The present paper aims at introducing the full resolution algorithm and comparing it with its simplified version in terms of computational efficiency and solution accuracy. In particular, it is shown that both algorithms lead to very similar identified solutions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frederick, P.R.

The purpose of this research was to provide a handbook on Project PETROL RAM and its ideas for enhancing the base-level fuels operations. This handbook is to serve as an introduction and reference guide to the components, characteristics, and capabilities of the proposed initiative. In preparing this handbook, available information on the structure, operations, and procedures of a typical base Fuels Management Branch was gathered, then condensed and simplified. For added depth and understanding, personal interviews with personnel involved in the design and development of this project were conducted. The research resulted in a handbook that describes, in simplified terminology,more » the different systems which are being developed under the Project PETROL RAM initiative.« less

Energy and water vapor transport across a simplified cloud-clear air interface

NASA Astrophysics Data System (ADS)

Gallana, L.; Di Savino, S.; De Santi, F.; Iovieno, M.; Tordella, D.

2014-11-01

We consider a simplified physics of the could interface where condensation, evaporation and radiation are neglected and momentum, thermal energy and water vapor transport is represented in terms of the Boussinesq model coupled to a passive scalar transport equation for the vapor. The interface is modeled as a layer separating two isotropic turbulent regions with different kinetic energy and vapor concentration. In particular, we focus on the small scale part of the inertial range of the atmospheric boundary layer as well as on the dissipative range of scales which are important to the micro-physics of warm clouds. We have numerically investigated stably stratified interfaces by locally perturbing at an initial instant the standard temperature lapse rate at the cloud interface and then observing the temporal evolution of the system. When the buoyancy term becomes of the same order of the inertial one, we observe a spatial redistribution of the kinetic energy which produce a concomitant pit of kinetic energy within the mixing layer. In this situation, the mixing layer contains two interfacial regions with opposite kinetic energy gradient, which in turn produces two intermittent sublayers in the velocity fluctuations field. This changes the structure of the field with respect to the corresponding non-stratified shearless mixing: the communication between the two turbulent region is weak, and the growth of the mixing layer stops. These results are discussed with respect to Large Eddy Simulations data for the Planetary Boundary Layers.

Report of the 1988 2-D Intercomparison Workshop, chapter 3

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Brasseur, Guy; Soloman, Susan; Guthrie, Paul D.; Garcia, Rolando; Yung, Yuk L.; Gray, Lesley J.; Tung, K. K.; Ko, Malcolm K. W.; Isaken, Ivar

1989-01-01

Several factors contribute to the errors encountered. With the exception of the line-by-line model, all of the models employ simplifying assumptions that place fundamental limits on their accuracy and range of validity. For example, all 2-D modeling groups use the diffusivity factor approximation. This approximation produces little error in tropospheric H2O and CO2 cooling rates, but can produce significant errors in CO2 and O3 cooling rates at the stratopause. All models suffer from fundamental uncertainties in shapes and strengths of spectral lines. Thermal flux algorithms being used in 2-D tracer tranport models produce cooling rates that differ by as much as 40 percent for the same input model atmosphere. Disagreements of this magnitude are important since the thermal cooling rates must be subtracted from the almost-equal solar heating rates to derive the net radiative heating rates and the 2-D model diabatic circulation. For much of the annual cycle, the net radiative heating rates are comparable in magnitude to the cooling rate differences described. Many of the models underestimate the cooling rates in the middle and lower stratosphere. The consequences of these errors for the net heating rates and the diabatic circulation will depend on their meridional structure, which was not tested here. Other models underestimate the cooling near 1 mbar. Suchs errors pose potential problems for future interactive ozone assessment studies, since they could produce artificially-high temperatures and increased O3 destruction at these levels. These concerns suggest that a great deal of work is needed to improve the performance of thermal cooling rate algorithms used in the 2-D tracer transport models.

Examination of Wave Speed in Rotating Detonation Engines Using Simplified Computational Fluid Dynamics

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.

2018-01-01

A simplified, two-dimensional, computational fluid dynamic (CFD) simulation, with a reactive Euler solver is used to examine possible causes for the low detonation wave propagation speeds that are consistently observed in air breathing rotating detonation engine (RDE) experiments. Intense, small-scale turbulence is proposed as the primary mechanism. While the solver cannot model this turbulence, it can be used to examine the most likely, and profound effect of turbulence. That is a substantial enlargement of the reaction zone, or equivalently, an effective reduction in the chemical reaction rate. It is demonstrated that in the unique flowfield of the RDE, a reduction in reaction rate leads to a reduction in the detonation speed. A subsequent test of reduced reaction rate in a purely one-dimensional pulsed detonation engine (PDE) flowfield yields no reduction in wave speed. The reasons for this are explained. The impact of reduced wave speed on RDE performance is then examined, and found to be minimal. Two other potential mechanisms are briefly examined. These are heat transfer, and reactive mixture non-uniformity. In the context of the simulation used for this study, both mechanisms are shown to have negligible effect on either wave speed or performance.

Plasmonic platforms of self-assembled silver nanostructures in application to fluorescence

PubMed Central

Luchowski, Rafal; Calander, Nils; Shtoyko, Tanya; Apicella, Elisa; Borejdo, Julian; Gryczynski, Zygmunt; Gryczynski, Ignacy

2011-01-01

Fluorescence intensity changes were investigated theoretically and experimentally using self-assembled colloidal structures on silver semitransparent mirrors. Using a simplified quasi-static model and finite element method, we demonstrate that near-field interactions of metallic nanostructures with a continuous metallic surface create conditions that produce enormously enhanced surface plasmon resonances. The results were used to explain the observed enhancements and determine the optimal conditions for the experiment. The theoretical parts of the studies are supported with reports on detailed emission intensity changes which provided multiple fluorescence hot spots with 2–3 orders of enhancements. We study two kinds of the fluorophores: dye molecules and fluorescent nanospheres characterized with similar spectral emission regions. Using a lifetime-resolved fluorescence/reflection confocal microscopy technique, we find that the largest rate for enhancement (~1000-fold) comes from localized areas of silver nanostructures. PMID:21403765

Navier-Stokes calculations on multi-element airfoils using a chimera-based solver

NASA Technical Reports Server (NTRS)

Jasper, Donald W.; Agrawal, Shreekant; Robinson, Brian A.

1993-01-01

A study of Navier-Stokes calculations of flows about multielement airfoils using a chimera grid approach is presented. The chimera approach utilizes structured, overlapped grids which allow great flexibility of grid arrangement and simplifies grid generation. Calculations are made for two-, three-, and four-element airfoils, and modeling of the effect of gap distance between elements is demonstrated for a two element case. Solutions are obtained using the thin-layer form of the Reynolds averaged Navier-Stokes equations with turbulence closure provided by the Baldwin-Lomax algebraic model or the Baldwin-Barth one equation model. The Baldwin-Barth turbulence model is shown to provide better agreement with experimental data and to dramatically improve convergence rates for some cases. Recently developed, improved farfield boundary conditions are incorporated into the solver for greater efficiency. Computed results show good comparison with experimental data which include aerodynamic forces, surface pressures, and boundary layer velocity profiles.

The abundance and variety of carbohydrate-active enzymes in the human gut microbiota.

PubMed

El Kaoutari, Abdessamad; Armougom, Fabrice; Gordon, Jeffrey I; Raoult, Didier; Henrissat, Bernard

2013-07-01

Descriptions of the microbial communities that live on and in the human body have progressed at a spectacular rate over the past 5 years, fuelled primarily by highly parallel DNA-sequencing technologies and associated advances in bioinformatics, and by the expectation that understanding how to manipulate the structure and functions of our microbiota will allow us to affect health and prevent or treat diseases. Among the myriad of genes that have been identified in the human gut microbiome, those that encode carbohydrate-active enzymes (CAZymes) are of particular interest, as these enzymes are required to digest most of our complex repertoire of dietary polysaccharides. In this Analysis article, we examine the carbohydrate-digestive capacity of a simplified but representative mini-microbiome in order to highlight the abundance and variety of bacterial CAZymes that are represented in the human gut microbiota.

The development of flux-split algorithms for flows with non-equilibrium thermodynamics and chemical reactions

NASA Technical Reports Server (NTRS)

Grossman, B.; Cinella, P.

1988-01-01

A finite-volume method for the numerical computation of flows with nonequilibrium thermodynamics and chemistry is presented. A thermodynamic model is described which simplifies the coupling between the chemistry and thermodynamics and also results in the retention of the homogeneity property of the Euler equations (including all the species continuity and vibrational energy conservation equations). Flux-splitting procedures are developed for the fully coupled equations involving fluid dynamics, chemical production and thermodynamic relaxation processes. New forms of flux-vector split and flux-difference split algorithms are embodied in a fully coupled, implicit, large-block structure, including all the species conservation and energy production equations. Several numerical examples are presented, including high-temperature shock tube and nozzle flows. The methodology is compared to other existing techniques, including spectral and central-differenced procedures, and favorable comparisons are shown regarding accuracy, shock-capturing and convergence rates.

The Partition Between Terminal Speed and Mass Loss: Thin, Thick, and Rotating Line-Driven Winds

NASA Astrophysics Data System (ADS)

Gayley, K. G.; Onifer, A. J.

2003-01-01

Steady-state supersonic line-driven winds are important contributors to wind-blown bubbles in star forming regions. The key input to the bubble in the energy-conserving phase is the wind kinetic-energy flux, which involves both the mass-loss rate and the terminal speed. However, these quantities are themselves self-consistent parameters of the line-driving process, so relate to each other and to the resulting wind optical depth. This complex interrelation between optical depth, mass-loss, and wind speed lies at the heart of line-driven wind theory. Drawing on the successes and insights of ``CAK'' theory, I will convey a simplified view of how to unite these processes using the concept of effective opacity, with attention to the ramifications for nonspherical nebular and wind-blown structures. Recent extensions to nongray optically thick environments such as Wolf-Rayet winds and supernovae are also discussed.

Design and fabrication of hybrid SPP waveguides for ultrahigh-bandwidth low-penalty terabit-scale data transmission.

PubMed

Du, Jing; Wang, Jian

2017-11-27

Here we design and fabricate a hybrid surface plasmon polarities (SPP) waveguide on the silicon-on-insulator (SOI) photonics platform. The designed hybrid SPP waveguide is composed of a metal ridge, an air gap, and a silicon ridge. We simulate the mode characteristics in the structure and design the waveguide with a wide air gap that can simplify the fabrication process and maintain the advantages of the hybrid SPP mode. The performance of ultrahigh-bandwidth data transmission through the proposed waveguide is then investigated using 161 wavelength-division multiplexing (WDM) channels, each carrying a 11.2-Gbit/s orthogonal frequency-division multiplexing (OFDM) 16-ary quadrature amplitude modulation (16-QAM) signal. The bit-error rates (BERs) of all 161 channels are less than 1e-3. The favorable results show the prospect of on-chip optical interconnection using the proposed hybrid SPP waveguide.

Photogrammetric Modeling and Image-Based Rendering for Rapid Virtual Environment Creation

DTIC Science & Technology

2004-12-01

area and different methods have been proposed. Pertinent methods include: Camera Calibration , Structure from Motion, Stereo Correspondence, and Image...Based Rendering 1.1.1 Camera Calibration Determining the 3D structure of a model from multiple views becomes simpler if the intrinsic (or internal...can introduce significant nonlinearities into the image. We have found that camera calibration is a straightforward process which can simplify the

Simplified Dynamic Structural Time History Response Analysis of Flexible Approach Walls Founded on Clustered Pile Groups Using Impact_Deck

DTIC Science & Technology

2016-07-01

Abstract Flexible approach walls are being considered for retrofits, replacements, or upgrades to Corps lock structures that have exceeded their...case of Lock and Dam 3, the peak reaction force for any individual pile group was 11% of the peak impact load. DISCLAIMER: The contents of this...Generation Flexible Approach Walls ......................................... 1 1.2.1 Lock and Dam 3

Highly Simplified Tandem Organic Light-Emitting Devices Incorporating a Green Phosphorescence Ultrathin Emitter within a Novel Interface Exciplex for High Efficiency.

PubMed

Xu, Ting; Zhou, Jun-Gui; Huang, Chen-Chao; Zhang, Lei; Fung, Man-Keung; Murtaza, Imran; Meng, Hong; Liao, Liang-Sheng

2017-03-29

Herein we report a novel design philosophy of tandem OLEDs incorporating a doping-free green phosphorescent bis[2-(2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) (Ir(ppy) 2 (acac)) as an ultrathin emissive layer (UEML) into a novel interface-exciplex-forming structure of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TmPyPB). Particularly, relatively low working voltage and remarkable efficiency are achieved and the designed tandem OLEDs exhibit a peak current efficiency of 135.74 cd/A (EQE = 36.85%) which is two times higher than 66.2 cd/A (EQE = 17.97%) of the device with a single emitter unit. This might be one of the highest efficiencies of OLEDs applying ultrathin emitters without light extraction. Moreover, with the proposed structure, the color gamut of the displays can be effectively increased from 76% to 82% NTSC if the same red and blue emissions as those in the NTSC are applied. A novel form of harmonious fusion among interface exciplex, UEML, and tandem structure is successfully realized, which sheds light on further development of ideal OLED structure with high efficiency, simplified fabrication, low power consumption, low cost, and improved color gamut, simultaneously.

Adolescent cocaine exposure simplifies orbitofrontal cortical dendritic arbors

PubMed Central

DePoy, Lauren M.; Perszyk, Riley E.; Zimmermann, Kelsey S.; Koleske, Anthony J.; Gourley, Shannon L.

2014-01-01

Cocaine and amphetamine remodel dendritic spines within discrete cortico-limbic brain structures including the orbitofrontal cortex (oPFC). Whether dendrite structure is similarly affected, and whether pre-existing cellular characteristics influence behavioral vulnerabilities to drugs of abuse, remain unclear. Animal models provide an ideal venue to address these issues because neurobehavioral phenotypes can be defined both before, and following, drug exposure. We exposed mice to cocaine from postnatal days 31–35, corresponding to early adolescence, using a dosing protocol that causes impairments in an instrumental reversal task in adulthood. We then imaged and reconstructed excitatory neurons in deep-layer oPFC. Prior cocaine exposure shortened and simplified arbors, particularly in the basal region. Next, we imaged and reconstructed orbital neurons in a developmental-genetic model of cocaine vulnerability—the p190rhogap+/– mouse. p190RhoGAP is an actin cytoskeleton regulatory protein that stabilizes dendrites and dendritic spines, and p190rhogap+/– mice develop rapid and robust locomotor activation in response to cocaine. Despite this, oPFC dendritic arbors were intact in drug-naïve p190rhogap+/– mice. Together, these findings provide evidence that adolescent cocaine exposure has long-term effects on dendrite structure in the oPFC, and they suggest that cocaine-induced modifications in dendrite structure may contribute to the behavioral effects of cocaine more so than pre-existing structural abnormalities in this cell population. PMID:25452728

A simplified method for monomeric carbohydrate analysis of corn stover biomass

USDA-ARS?s Scientific Manuscript database

Constituent determination of biomass for theoretical ethanol yield (TEY) estimation requires the removal of non-structural carbohydrates prior to analysis to prevent interference with the analytical procedure. According to the accepted U.S. Dept. of Energy-National Renewable Energy Laboratory (NREL)...

A simplified method for prediction of long-term prestress loss in post-tensioned concrete bridges.

DOT National Transportation Integrated Search

2006-07-01

Creep and shrinkage of concrete and relaxation of prestressing steel cause time-dependent changes in : the stresses and strains of concrete structures. These changes result in continuous reduction in the : concrete compression stresses and in the ten...

The Mad Fox Disease: Rabies.

ERIC Educational Resources Information Center

Keller, Rosanne

One of a series of instructional materials produced by the Literacy Council of Alaska, this booklet provides information about the control of rabies. Using both simplified sentence structure and vocabulary, it describes how rabies may be spread, its symptoms, its treatment, and ways it can be prevented. (FL)

DOE Office of Scientific and Technical Information (OSTI.GOV)

König, Johannes; Merle, Alexander; Totzauer, Maximilian

We investigate the early Universe production of sterile neutrino Dark Matter by the decays of singlet scalars. All previous studies applied simplifying assumptions and/or studied the process only on the level of number densities, which makes it impossible to give statements about cosmic structure formation. We overcome these issues by dropping all simplifying assumptions (except for one we showed earlier to work perfectly) and by computing the full course of Dark Matter production on the level of non-thermal momentum distribution functions. We are thus in the position to study a broad range of aspects of the resulting settings and applymore » a broad set of bounds in a reliable manner. We have a particular focus on how to incorporate bounds from structure formation on the level of the linear power spectrum, since the simplistic estimate using the free-streaming horizon clearly fails for highly non-thermal distributions. Our work comprises the most detailed and comprehensive study of sterile neutrino Dark Matter production by scalar decays presented so far.« less

Quantum theory of the structure and bonding in proteins. Part 11. A simplified method and its application to the α-amino-isobutyric acid residue

NASA Astrophysics Data System (ADS)

Peters, David; Peters, Jane

Information about the preferred conformation of the α-amino-isobutyric acid residue (α-AIB) is obtained without explicit computation of its wave function. The conformation of lowest energy of this residue is close to the usual helical conformation and so the residue may occur at the 2 position of a type I or I' bend or in either position of a type III or III' bend. The available experimental information refers to a β bend formed from α-AIB-PRO and then the theory and experiment agree that the only possibility is a type III bend. It is predicted that a β sheet structure may be formed at rather higher energy and in the planar and not the pleated form. There is no apparent reason why this residue should not form an α helix. The simplified method used here is closely related to the partitioned potential energy methods which are widely used in this subject.

Characterization and calibration of a viscoelastic simplified potential energy clock model for inorganic glasses

DOE PAGES

Chambers, Robert S.; Tandon, Rajan; Stavig, Mark E.

2015-07-07

In this study, to analyze the stresses and strains generated during the solidification of glass-forming materials, stress and volume relaxation must be predicted accurately. Although the modeling attributes required to depict physical aging in organic glassy thermosets strongly resemble the structural relaxation in inorganic glasses, the historical modeling approaches have been distinctly different. To determine whether a common constitutive framework can be applied to both classes of materials, the nonlinear viscoelastic simplified potential energy clock (SPEC) model, developed originally for glassy thermosets, was calibrated for the Schott 8061 inorganic glass and used to analyze a number of tests. A practicalmore » methodology for material characterization and model calibration is discussed, and the structural relaxation mechanism is interpreted in the context of SPEC model constitutive equations. SPEC predictions compared to inorganic glass data collected from thermal strain measurements and creep tests demonstrate the ability to achieve engineering accuracy and make the SPEC model feasible for engineering applications involving a much broader class of glassy materials.« less

Two-Dimensional Hermite Filters Simplify the Description of High-Order Statistics of Natural Images.

PubMed

Hu, Qin; Victor, Jonathan D

2016-09-01

Natural image statistics play a crucial role in shaping biological visual systems, understanding their function and design principles, and designing effective computer-vision algorithms. High-order statistics are critical for conveying local features, but they are challenging to study - largely because their number and variety is large. Here, via the use of two-dimensional Hermite (TDH) functions, we identify a covert symmetry in high-order statistics of natural images that simplifies this task. This emerges from the structure of TDH functions, which are an orthogonal set of functions that are organized into a hierarchy of ranks. Specifically, we find that the shape (skewness and kurtosis) of the distribution of filter coefficients depends only on the projection of the function onto a 1-dimensional subspace specific to each rank. The characterization of natural image statistics provided by TDH filter coefficients reflects both their phase and amplitude structure, and we suggest an intuitive interpretation for the special subspace within each rank.

Latent transition models with latent class predictors: attention deficit hyperactivity disorder subtypes and high school marijuana use

PubMed Central

Reboussin, Beth A.; Ialongo, Nicholas S.

2011-01-01

Summary Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder which is most often diagnosed in childhood with symptoms often persisting into adulthood. Elevated rates of substance use disorders have been evidenced among those with ADHD, but recent research focusing on the relationship between subtypes of ADHD and specific drugs is inconsistent. We propose a latent transition model (LTM) to guide our understanding of how drug use progresses, in particular marijuana use, while accounting for the measurement error that is often found in self-reported substance use data. We extend the LTM to include a latent class predictor to represent empirically derived ADHD subtypes that do not rely on meeting specific diagnostic criteria. We begin by fitting two separate latent class analysis (LCA) models by using second-order estimating equations: a longitudinal LCA model to define stages of marijuana use, and a cross-sectional LCA model to define ADHD subtypes. The LTM model parameters describing the probability of transitioning between the LCA-defined stages of marijuana use and the influence of the LCA-defined ADHD subtypes on these transition rates are then estimated by using a set of first-order estimating equations given the LCA parameter estimates. A robust estimate of the LTM parameter variance that accounts for the variation due to the estimation of the two sets of LCA parameters is proposed. Solving three sets of estimating equations enables us to determine the underlying latent class structures independently of the model for the transition rates and simplifying assumptions about the correlation structure at each stage reduces the computational complexity. PMID:21461139

Oral health survey and oral health questionnaire for high school students in Tibet, China

PubMed Central

2014-01-01

Objectives The aim of this study is to identify the oral health status as well as oral health practices and access for care of graduating senior high school Tibetan students in Shannan prefecture of Tibet. Methods Based on standards of the 3rd Chinese National Oral Epidemiological Survey and WHO Oral Health Surveys, 1907 graduating students from three senior high schools were examined for caries, periodontitis, dental fluorosis, and oral hygiene status. The questionnaire to the students addressed oral health practices and present access to oral medical services. Results Dental caries prevalence (39.96%) and mean DMFT (0.97) were high in Tibetan students. In community periodontal indexes, the detection rate of gingivitis and dental calculus were 59.50% and 62.64%, respectively. Oral hygiene index-simplified was 0.69, with 0.36 and 0.33 in debris index-simplified and calculus index-simplified, respectively. Community dental fluorosis index was 0.29, with 8.13% in prevalence rate. The questionnaire showed students had poor oral health practices and unawareness for their needs for oral health services. It was also noted that the local area provides inadequate oral medical services. Conclusions Tibetan students had higher prevalence of dental diseases and lower awareness of oral health needs. The main reasons were geographical environment, dietary habit, students’ attitude to oral health, and lack of oral health promotion and education. Oral health education and local dentists training should be strengthened to get effective prevention of dental diseases. PMID:24884668

Mathematical Description of Complex Chemical Kinetics and Application to CFD Modeling Codes

NASA Technical Reports Server (NTRS)

Bittker, D. A.

1993-01-01

A major effort in combustion research at the present time is devoted to the theoretical modeling of practical combustion systems. These include turbojet and ramjet air-breathing engines as well as ground-based gas-turbine power generating systems. The ability to use computational modeling extensively in designing these products not only saves time and money, but also helps designers meet the quite rigorous environmental standards that have been imposed on all combustion devices. The goal is to combine the very complex solution of the Navier-Stokes flow equations with realistic turbulence and heat-release models into a single computer code. Such a computational fluid-dynamic (CFD) code simulates the coupling of fluid mechanics with the chemistry of combustion to describe the practical devices. This paper will focus on the task of developing a simplified chemical model which can predict realistic heat-release rates as well as species composition profiles, and is also computationally rapid. We first discuss the mathematical techniques used to describe a complex, multistep fuel oxidation chemical reaction and develop a detailed mechanism for the process. We then show how this mechanism may be reduced and simplified to give an approximate model which adequately predicts heat release rates and a limited number of species composition profiles, but is computationally much faster than the original one. Only such a model can be incorporated into a CFD code without adding significantly to long computation times. Finally, we present some of the recent advances in the development of these simplified chemical mechanisms.

Mathematical description of complex chemical kinetics and application to CFD modeling codes

NASA Technical Reports Server (NTRS)

Bittker, D. A.

1993-01-01

A major effort in combustion research at the present time is devoted to the theoretical modeling of practical combustion systems. These include turbojet and ramjet air-breathing engines as well as ground-based gas-turbine power generating systems. The ability to use computational modeling extensively in designing these products not only saves time and money, but also helps designers meet the quite rigorous environmental standards that have been imposed on all combustion devices. The goal is to combine the very complex solution of the Navier-Stokes flow equations with realistic turbulence and heat-release models into a single computer code. Such a computational fluid-dynamic (CFD) code simulates the coupling of fluid mechanics with the chemistry of combustion to describe the practical devices. This paper will focus on the task of developing a simplified chemical model which can predict realistic heat-release rates as well as species composition profiles, and is also computationally rapid. We first discuss the mathematical techniques used to describe a complex, multistep fuel oxidation chemical reaction and develop a detailed mechanism for the process. We then show how this mechanism may be reduced and simplified to give an approximate model which adequately predicts heat release rates and a limited number of species composition profiles, but is computationally much faster than the original one. Only such a model can be incorporated into a CFD code without adding significantly to long computation times. Finally, we present some of the recent advances in the development of these simplified chemical mechanisms.

Uncertainty Analysis of Air Radiation for Lunar Return Shock Layers

NASA Technical Reports Server (NTRS)

Kleb, Bil; Johnston, Christopher O.

2008-01-01

By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).

A phylogenetic analysis of normal modes evolution in enzymes and its relationship to enzyme function

PubMed Central

Lai, Jason; Jin, Jing; Kubelka, Jan; Liberles, David A.

2012-01-01

Since the dynamic nature of protein structures is essential for enzymatic function, it is expected that the functional evolution can be inferred from the changes in the protein dynamics. However, dynamics can also diverge neutrally with sequence substitution between enzymes without changes of function. In this study, a phylogenetic approach is implemented to explore the relationship between enzyme dynamics and function through evolutionary history. Protein dynamics are described by normal mode analysis based on a simplified harmonic potential force field applied to the reduced Cα representation of the protein structure while enzymatic function is described by Enzyme Commission (EC) numbers. Similarity of the binding pocket dynamics at each branch of the protein family’s phylogeny was analyzed in two ways: 1) explicitly by quantifying the normal mode overlap calculated for the reconstructed ancestral proteins at each end and 2) implicitly using a diffusion model to obtain the reconstructed lineage-specific changes in the normal modes. Both explicit and implicit ancestral reconstruction identified generally faster rates of change in dynamics compared with the expected change from neutral evolution at the branches of potential functional divergences for the alpha-amylase, D-isomer specific 2-hydroxyacid dehydrogenase, and copper-containing amine oxidase protein families. Normal modes analysis added additional information over just comparing the RMSD of static structures. However, the branch-specific changes were not statistically significant compared to background function-independent neutral rates of change of dynamic properties and blind application of the analysis would not enable prediction of changes in enzyme specificity. PMID:22651983

A phylogenetic analysis of normal modes evolution in enzymes and its relationship to enzyme function.

PubMed

Lai, Jason; Jin, Jing; Kubelka, Jan; Liberles, David A

2012-09-21

Since the dynamic nature of protein structures is essential for enzymatic function, it is expected that functional evolution can be inferred from the changes in protein dynamics. However, dynamics can also diverge neutrally with sequence substitution between enzymes without changes of function. In this study, a phylogenetic approach is implemented to explore the relationship between enzyme dynamics and function through evolutionary history. Protein dynamics are described by normal mode analysis based on a simplified harmonic potential force field applied to the reduced C(α) representation of the protein structure while enzymatic function is described by Enzyme Commission numbers. Similarity of the binding pocket dynamics at each branch of the protein family's phylogeny was analyzed in two ways: (1) explicitly by quantifying the normal mode overlap calculated for the reconstructed ancestral proteins at each end and (2) implicitly using a diffusion model to obtain the reconstructed lineage-specific changes in the normal modes. Both explicit and implicit ancestral reconstruction identified generally faster rates of change in dynamics compared with the expected change from neutral evolution at the branches of potential functional divergences for the α-amylase, D-isomer-specific 2-hydroxyacid dehydrogenase, and copper-containing amine oxidase protein families. Normal mode analysis added additional information over just comparing the RMSD of static structures. However, the branch-specific changes were not statistically significant compared to background function-independent neutral rates of change of dynamic properties and blind application of the analysis would not enable prediction of changes in enzyme specificity. Copyright © 2012 Elsevier Ltd. All rights reserved.

A simplified orthotropic formulation of the viscoplasticity theory based on overstress

NASA Technical Reports Server (NTRS)

Sutcu, M.; Krempl, E.

1988-01-01

An orthotropic, small strain viscoplasticity theory based on overstress is presented. In each preferred direction the stress is composed of time (rate) independent (or plastic) and viscous (or rate dependent) contributions. Tension-compression asymmetry can depend on direction and is included in the model. Upon a proper choice of a material constant one preferred direction can exhibit linear elastic response while the other two deform in a viscoplastic manner.

Vibrational Energy Transfer within the B 3Pi (0(+) sub u) State of 79BR2 Upon Collision with N2, O2, NO, and SF6

DTIC Science & Technology

1993-12-01

molecular radii derived for a (6,12) Lennard - Jones potential from viscosity data tabulated in reference (7). 49 Table A. 1. Gas Kinetic Collision...transfer rates and electronic quenching rates of the diatomic interhalogens in determining potential candidates for visible chemical lasers. This thesis...configuration ..................... 4 2. B2 potential energy curves ................................................................... 5 3. Simplified

Solid State Mini-RPV Color Imaging System

DTIC Science & Technology

1975-09-12

completed in the design and construction phase . Con- siderations are now in progress for conducting field tests of the equipment against "real world...Simplified Parallel Injection Configuration 2-21 CID Parallel Injection Configuration 2-23 Element Rate Timing 2-25 Horizontal Input and Phase Line...Timing 2-26 Line Reset /Injection Timing 2-27 Line Rate Timing (Start of Readout) 2-28 Driver A4 Block Diagram 2-31 Element Scan Time Base

Mass-loss rates of cool stars

NASA Astrophysics Data System (ADS)

Katrien Els Decin, Leen

2015-08-01

Over much of the initial mass function, stars lose a significant fraction of their mass through a stellar wind during the late stages of their evolution when being a (super)giant star. As of today, we can not yet predict the mass-loss rate during the (super)giant phase for a given star with specific stellar parameters from first principles. This uncertainty directly impacts the accuracy of current stellar evolution and population synthesis models that predict the enrichment of the interstellar medium by these stellar winds. Efforts to establish the link between the initial physical and chemical conditions at stellar birth and the mass-loss rate during the (super)giant phase have proceeded on two separate tracks: (1) more detailed studies of the chemical and morpho-kinematical structure of the stellar winds of (super)giant stars in our own Milky Way by virtue of the proximity, and (2) large scale and statistical studies of a (large) sample of stars in other galaxies (such as the LMC and SMC) and globular clusters eliminating the uncertainty on the distance estimate and providing insight into the dependence of the mass-loss rate on the metallicity. In this review, I will present recent results of both tracks, will show how recent measurements confirm (some) theoretical predictions, but also how results from the first track admonish of common misconceptions inherent in the often more simplified analysis used to analyse the large samples from track 2.

Optimisation and evaluation of pre-design models for offshore wind turbines with jacket support structures and their influence on integrated load simulations

NASA Astrophysics Data System (ADS)

Schafhirt, S.; Kaufer, D.; Cheng, P. W.

2014-12-01

In recent years many advanced load simulation tools, allowing an aero-servo-hydroelastic analyses of an entire offshore wind turbine, have been developed and verified. Nowadays, even an offshore wind turbine with a complex support structure such as a jacket can be analysed. However, the computational effort rises significantly with an increasing level of details. This counts especially for offshore wind turbines with lattice support structures, since those models do naturally have a higher number of nodes and elements than simpler monopile structures. During the design process multiple load simulations are demanded to obtain an optimal solution. In the view of pre-design tasks it is crucial to apply load simulations which keep the simulation quality and the computational effort in balance. The paper will introduce a reference wind turbine model consisting of the REpower5M wind turbine and a jacket support structure with a high level of detail. In total twelve variations of this reference model are derived and presented. Main focus is to simplify the models of the support structure and the foundation. The reference model and the simplified models are simulated with the coupled simulation tool Flex5-Poseidon and analysed regarding frequencies, fatigue loads, and ultimate loads. A model has been found which reaches an adequate increase of simulation speed while holding the results in an acceptable range compared to the reference results.

Efficient finite element modelling for the investigation of the dynamic behaviour of a structure with bolted joints

NASA Astrophysics Data System (ADS)

Omar, R.; Rani, M. N. Abdul; Yunus, M. A.; Mirza, W. I. I. Wan Iskandar; Zin, M. S. Mohd

2018-04-01

A simple structure with bolted joints consists of the structural components, bolts and nuts. There are several methods to model the structures with bolted joints, however there is no reliable, efficient and economic modelling methods that can accurately predict its dynamics behaviour. Explained in this paper is an investigation that was conducted to obtain an appropriate modelling method for bolted joints. This was carried out by evaluating four different finite element (FE) models of the assembled plates and bolts namely the solid plates-bolts model, plates without bolt model, hybrid plates-bolts model and simplified plates-bolts model. FE modal analysis was conducted for all four initial FE models of the bolted joints. Results of the FE modal analysis were compared with the experimental modal analysis (EMA) results. EMA was performed to extract the natural frequencies and mode shapes of the test physical structure with bolted joints. Evaluation was made by comparing the number of nodes, number of elements, elapsed computer processing unit (CPU) time, and the total percentage of errors of each initial FE model when compared with EMA result. The evaluation showed that the simplified plates-bolts model could most accurately predict the dynamic behaviour of the structure with bolted joints. This study proved that the reliable, efficient and economic modelling of bolted joints, mainly the representation of the bolting, has played a crucial element in ensuring the accuracy of the dynamic behaviour prediction.

Simplified models of dark matter with a long-lived co-annihilation partner

NASA Astrophysics Data System (ADS)

Khoze, Valentin V.; Plascencia, Alexis D.; Sakurai, Kazuki

2017-06-01

We introduce a new set of simplified models to address the effects of 3-point interactions between the dark matter particle, its dark co-annihilation partner, and the Standard Model degree of freedom, which we take to be the tau lepton. The contributions from dark matter co-annihilation channels are highly relevant for a determination of the correct relic abundance. We investigate these effects as well as the discovery potential for dark matter co-annihilation partners at the LHC. A small mass splitting between the dark matter and its partner is preferred by the co-annihilation mechanism and suggests that the co-annihilation partners may be long-lived (stable or meta-stable) at collider scales. It is argued that such long-lived electrically charged particles can be looked for at the LHC in searches of anomalous charged tracks. This approach and the underlying models provide an alternative/complementarity to the mono-jet and multi-jet based dark matter searches widely used in the context of simplified models with s-channel mediators. We consider four types of simplified models with different particle spins and coupling structures. Some of these models are manifestly gauge invariant and renormalizable, others would ultimately require a UV completion. These can be realised in terms of supersymmetric models in the neutralino-stau co-annihilation regime, as well as models with extra dimensions or composite models.

A Simplified Mesh Deformation Method Using Commercial Structural Analysis Software

NASA Technical Reports Server (NTRS)

Hsu, Su-Yuen; Chang, Chau-Lyan; Samareh, Jamshid

2004-01-01

Mesh deformation in response to redefined or moving aerodynamic surface geometries is a frequently encountered task in many applications. Most existing methods are either mathematically too complex or computationally too expensive for usage in practical design and optimization. We propose a simplified mesh deformation method based on linear elastic finite element analyses that can be easily implemented by using commercially available structural analysis software. Using a prescribed displacement at the mesh boundaries, a simple structural analysis is constructed based on a spatially varying Young s modulus to move the entire mesh in accordance with the surface geometry redefinitions. A variety of surface movements, such as translation, rotation, or incremental surface reshaping that often takes place in an optimization procedure, may be handled by the present method. We describe the numerical formulation and implementation using the NASTRAN software in this paper. The use of commercial software bypasses tedious reimplementation and takes advantage of the computational efficiency offered by the vendor. A two-dimensional airfoil mesh and a three-dimensional aircraft mesh were used as test cases to demonstrate the effectiveness of the proposed method. Euler and Navier-Stokes calculations were performed for the deformed two-dimensional meshes.

Simplified ZrTiO x -based RRAM cell structure with rectifying characteristics by integrating Ni/n + -Si diode.

PubMed

Lin, Chia-Chun; Wu, Yung-Hsien; Chang, You-Tai; Sun, Cherng-En

2014-01-01

A simplified one-diode one-resistor (1D1R) resistive switching memory cell that uses only four layers of TaN/ZrTiO x /Ni/n(+)-Si was proposed to suppress sneak current where TaN/ZrTiO x /Ni can be regarded as a resistive-switching random access memory (RRAM) device while Ni/n(+)-Si acts as an Schottky diode. This is the first RRAM cell structure that employs metal/semiconductor Schottky diode for current rectifying. The 1D1R cell exhibits bipolar switching behavior with SET/RESET voltage close to 1 V without requiring a forming process. More importantly, the cell shows tight resistance distribution for different states, significantly rectifying characteristics with forward/reverse current ratio higher than 10(3) and a resistance ratio larger than 10(3) between two states. Furthermore, the cell also displays desirable reliability performance in terms of long data retention time of up to 10(4) s and robust endurance of 10(5) cycles. Based on the promising characteristics, the four-layer 1D1R structure holds the great potential for next-generation nonvolatile memory technology.

Simplified Structure of Ducted Darrieus-Type Hydro Turbine with Narrow Intake for Extra-low Head Hydropower Utilization

NASA Astrophysics Data System (ADS)

Matsushita, Daisuke; Okuma, Kusuo; Watanabe, Satoshi; Furukawa, Akinori

A ducted Darrieus-type hydro turbine has been proposed for extra-low head hydropower utilization of total head less than 2m, where development is almost not done in the commercial base. Though the efficiency of Darrieus-type turbine, which is cross flow type, is not so high as conventional type, the Darrieus-type has a cost-advantage due to the simple structure. By installing a narrow intake at upstream of the runner, the efficiency becomes higher than normal intake that a width of which is the same as one of runner section. In the case of normal intake, the casing clearance between the runner pitch circle and the side-wall at the runner section becomes the influential factor which deteriorates the efficiency. On the other hand, in the case of narrow intake, it is possible to keep efficiency high, based on the fact that the distorting flow to the clearance is prevented. In the present paper, the effects of narrow intake and draft tube on turbine performance are experimentally examined and the design guideline of simplified structure for ducted Darrieus-type turbine with narrow intake is proposed.

Simplified molecular input line entry system-based: QSAR modelling for MAP kinase-interacting protein kinase (MNK1).

PubMed

Begum, S; Achary, P Ganga Raju

2015-01-01

Quantitative structure-activity relationship (QSAR) models were built for the prediction of inhibition (pIC50, i.e. negative logarithm of the 50% effective concentration) of MAP kinase-interacting protein kinase (MNK1) by 43 potent inhibitors. The pIC50 values were modelled with five random splits, with the representations of the molecular structures by simplified molecular input line entry system (SMILES). QSAR model building was performed by the Monte Carlo optimisation using three methods: classic scheme; balance of correlations; and balance correlation with ideal slopes. The robustness of these models were checked by parameters as rm(2), r(*)m(2), [Formula: see text] and randomisation technique. The best QSAR model based on single optimal descriptors was applied to study in vitro structure-activity relationships of 6-(4-(2-(piperidin-1-yl) ethoxy) phenyl)-3-(pyridin-4-yl) pyrazolo [1,5-a] pyrimidine derivatives as a screening tool for the development of novel potent MNK1 inhibitors. The effects of alkyl group, -OH, -NO2, F, Cl, Br, I, etc. on the IC50 values towards the inhibition of MNK1 were also reported.

The performance of fine-grained and coarse-grained elastic network models and its dependence on various factors.

PubMed

Na, Hyuntae; Song, Guang

2015-07-01

In a recent work we developed a method for deriving accurate simplified models that capture the essentials of conventional all-atom NMA and identified two best simplified models: ssNMA and eANM, both of which have a significantly higher correlation with NMA in mean square fluctuation calculations than existing elastic network models such as ANM and ANMr2, a variant of ANM that uses the inverse of the squared separation distances as spring constants. Here, we examine closely how the performance of these elastic network models depends on various factors, namely, the presence of hydrogen atoms in the model, the quality of input structures, and the effect of crystal packing. The study reveals the strengths and limitations of these models. Our results indicate that ssNMA and eANM are the best fine-grained elastic network models but their performance is sensitive to the quality of input structures. When the quality of input structures is poor, ANMr2 is a good alternative for computing mean-square fluctuations while ANM model is a good alternative for obtaining normal modes. © 2015 Wiley Periodicals, Inc.

Adaptation of child oral health education leaflets for Arabic migrants in Australia: a qualitative study.

PubMed

Arora, Amit; Al-Salti, Ibrahim; Murad, Hussam; Tran, Quang; Itaoui, Rhonda; Bhole, Sameer; Ajwani, Shilpi; Jones, Charlotte; Manohar, Narendar

2018-01-10

The purpose of this study was to gain an in-depth understanding of Arabic-speaking mothers views on the usefulness of existing oral health education leaflets aimed at young children and also to record their views on the tailored versions of these leaflets. This qualitative study was nested within a large ongoing birth cohort study in South Western Sydney, Australia. Arabic-speaking mothers (n = 19) with young children were purposively selected and approached for a semi-structured interview. Two original English leaflets giving advice on young children's oral health were sent to mother's prior to the interview. On the day of interview, mothers were given simplified-English and Arabic versions of both the leaflets and were asked to compare the three versions. Interviews were audio-recorded, subsequently transcribed verbatim and analysed by thematic analysis. Ethical approval was obtained from Human Research Ethics Committees of the former Sydney South West Area Health Service, University of Sydney and Western Sydney University. Mothers reported that simplified English together with the Arabic version of the leaflets were useful sources of information. Although many mothers favoured the simplified version over original English leaflets, the majority favoured the leaflets in Arabic. Ideally, a "dual Arabic - simplified English leaflet" was preferred. The understanding of key health messages was optimised through a simple layout and visual images. There is a need to tailor oral health education leaflets for Arabic-speaking migrants. Producers of dental leaflets should also consider a "dual Arabic - simplified English leaflet" to improve oral health knowledge of Arabic-speaking migrants. The use of simple layout and pictures assists Arabic-speaking migrants to understand the content of dental leaflets.

Incompletely Mixed Surface Transient Storage Zones at River Restoration Structures: Modeling Implications

NASA Astrophysics Data System (ADS)

Endreny, T. A.; Robinson, J.

2012-12-01

River restoration structures, also known as river steering deflectors, are designed to reduce bank shear stress by generating wake zones between the bank and the constricted conveyance region. There is interest in characterizing the surface transient storage (STS) and associated biogeochemical processing in the STS zones around these structures to quantify the ecosystem benefits of river restoration. This research explored how the hydraulics around river restoration structures prohibits application of transient storage models designed for homogenous, completely mixed STS zones. We used slug and constant rate injections of a conservative tracer in a 3rd order river in Onondaga County, NY over the course of five experiments at varying flow regimes. Recovered breakthrough curves spanned a transect including the main channel and wake zone at a j-hook restoration structure. We noted divergent patterns of peak solute concentration and times within the wake zone regardless of transect location within the structure. Analysis reveals an inhomogeneous STS zone which is frequently still loading tracer after the main channel has peaked. The breakthrough curve loading patterns at the restoration structure violated the assumptions of simplified "random walk" 2 zone transient storage models which seek to identify representative STS zones and zone locations. Use of structure-scale Weiner filter based multi-rate mass transfer models to characterize STS zones residence times are similarly dependent on a representative zone location. Each 2 zone model assumes 1 zone is a completely mixed STS zone and the other a completely mixed main channel. Our research reveals limits to simple application of the recently developed 2 zone models, and raises important questions about the measurement scale necessary to identify critical STS properties at restoration sites. An explanation for the incompletely mixed STS zone may be the distinct hydraulics at restoration sites, including a constrained high velocity conveyance region closely abutting a wake zone that receives periodic disruption from the upstream structure shearing vortices.igure 1. River restoration j-hook with blue dye revealing main channel and edge of wake zone with multiple surface transient storage zones.

Pyro thruster for performing rocket booster attachment, disconnect, and jettison functions

NASA Technical Reports Server (NTRS)

Hornyak, Stephen

1989-01-01

The concept of a pyro thruster, combining an automatic structural attachment with quick disconnect and thrusting capability, is described. The purpose of the invention is to simplify booster installation, disengagement, and jettison functions for the U.S. Air Force Advanced Launch Systems (ALS) program.

Evaluation of Various Tack Coat Materials Using Interface Shear Device and Recommendations on a Simplified Device

DOT National Transportation Integrated Search

2017-12-01

The performance of pavement interface bonds affects the integrity of pavement structures. In current practice, tack coats are used to ensure sufficient bonding between asphalt concrete (AC) layers as well as AC and concrete or aggregate base layers. ...

Comparison of Traditional Design Nonlinear Programming Optimization and Stochastic Methods for Structural Design

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Pai, Shantaram S.; Coroneos, Rula M.

2010-01-01

Structural design generated by traditional method, optimization method and the stochastic design concept are compared. In the traditional method, the constraints are manipulated to obtain the design and weight is back calculated. In design optimization, the weight of a structure becomes the merit function with constraints imposed on failure modes and an optimization algorithm is used to generate the solution. Stochastic design concept accounts for uncertainties in loads, material properties, and other parameters and solution is obtained by solving a design optimization problem for a specified reliability. Acceptable solutions were produced by all the three methods. The variation in the weight calculated by the methods was modest. Some variation was noticed in designs calculated by the methods. The variation may be attributed to structural indeterminacy. It is prudent to develop design by all three methods prior to its fabrication. The traditional design method can be improved when the simplified sensitivities of the behavior constraint is used. Such sensitivity can reduce design calculations and may have a potential to unify the traditional and optimization methods. Weight versus reliabilitytraced out an inverted-S-shaped graph. The center of the graph corresponded to mean valued design. A heavy design with weight approaching infinity could be produced for a near-zero rate of failure. Weight can be reduced to a small value for a most failure-prone design. Probabilistic modeling of load and material properties remained a challenge.

A New Relationship Between Soft X-Rays and EUV Flare Light Curves

NASA Astrophysics Data System (ADS)

Thiemann, Edward

2016-05-01

Solar flares are the result of magnetic reconnection in the solar corona which converts magnetic energy into kinetic energy resulting in the rapid heating of solar plasma. As this plasma cools, it emits radiation at different EUV wavelengths when the dropping temperature passes a line’s temperature of formation. This results in a delay in the emissions from cooler EUV lines relative to hotter EUV lines. Therefore, characterizing how this hot plasma cools is important for understanding how the corresponding geo-effective extreme ultraviolet (EUV) irradiance evolves in time. I present a simple new framework in which to study flare cooling by using a Lumped Element Thermal Model (LETM). LETM is frequently used in science and engineering to simplify a complex multi-dimensional thermal system by reducing it to a 0-D thermal circuit. For example, a structure that conducts heat out of a system is simplified with a resistive element and a structure that allows a system to store heat is simplified with a capacitive element. A major advantage of LETM is that the specific geometry of a system can be ignored, allowing for an intuitive analysis of the major thermal processes. I show that LETM is able to accurately reproduce the temporal evolution of cooler flare emission lines based on hotter emission line evolution. In particular, it can be used to predict the evolution of EUV flare light curves using the NOAA X-Ray Sensor (XRS).

78 FR 34427 - 2012 Tax Information for Use In The Revenue Shortfall Allocation Method

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-07

... Information for Use In The Revenue Shortfall Allocation Method AGENCY: Surface Transportation Board, DOT... of American Railroads (AAR), for use in the Revenue Shortfall Allocation Method (RSAM). DATES... revised in Simplified Standards for Rail Rate Cases--Taxes in Revenue Shortfall Allocation Method, EP 646...

MODELING SMALL-SCALE SPILLS OF AQUEOUS SOLUTIONS IN THE INDOOR ENVIRONMENT

EPA Science Inventory

A mass transfer model is proposed to estimate the rates of chemical emissions from aqueous solutions spilled on hard surfaces inside buildings. The model is presented in two forms: a set of four ordinary differential equations and a simplified exact solution. The latter can be ...

Tax Wealth in Fifty States.

ERIC Educational Resources Information Center

Halstead, D. Kent

This study presents a scheme for yearly, comparative, computation of state and local government tax capacity and effort. Figures for all states for fiscal year 1975 are presented in extensive tables. The system used is a simplified version of the Representative Tax System, which identifies tax bases, determines national average tax rates for those…

A user-oriented and computerized model for estimating vehicle ride quality

NASA Technical Reports Server (NTRS)

Leatherwood, J. D.; Barker, L. M.

1984-01-01

A simplified empirical model and computer program for estimating passenger ride comfort within air and surface transportation systems are described. The model is based on subjective ratings from more than 3000 persons who were exposed to controlled combinations of noise and vibration in the passenger ride quality apparatus. This model has the capability of transforming individual elements of a vehicle's noise and vibration environment into subjective discomfort units and then combining the subjective units to produce a single discomfort index typifying passenger acceptance of the environment. The computational procedures required to obtain discomfort estimates are discussed, and a user oriented ride comfort computer program is described. Examples illustrating application of the simplified model to helicopter and automobile ride environments are presented.

Development of a Low-Lift Chiller Controller and Simplified Precooling Control Algorithm - Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gayeski, N.; Armstrong, Peter; Alvira, M.

2011-11-30

KGS Buildings LLC (KGS) and Pacific Northwest National Laboratory (PNNL) have developed a simplified control algorithm and prototype low-lift chiller controller suitable for model-predictive control in a demonstration project of low-lift cooling. Low-lift cooling is a highly efficient cooling strategy conceived to enable low or net-zero energy buildings. A low-lift cooling system consists of a high efficiency low-lift chiller, radiant cooling, thermal storage, and model-predictive control to pre-cool thermal storage overnight on an optimal cooling rate trajectory. We call the properly integrated and controlled combination of these elements a low-lift cooling system (LLCS). This document is the final report formore » that project.« less

Direct Synthesis of Microwave Waveforms for Quantum Computing

NASA Astrophysics Data System (ADS)

Raftery, James; Vrajitoarea, Andrei; Zhang, Gengyan; Leng, Zhaoqi; Srinivasan, Srikanth; Houck, Andrew

Current state of the art quantum computing experiments in the microwave regime use control pulses generated by modulating microwave tones with baseband signals generated by an arbitrary waveform generator (AWG). Recent advances in digital analog conversion technology have made it possible to directly synthesize arbitrary microwave pulses with sampling rates of 65 gigasamples per second (GSa/s) or higher. These new ultra-wide bandwidth AWG's could dramatically simplify the classical control chain for quantum computing experiments, presenting potential cost savings and reducing the number of components that need to be carefully calibrated. Here we use a Keysight M8195A AWG to study the viability of such a simplified scheme, demonstrating randomized benchmarking of a superconducting qubit with high fidelity.

A simulation study of emergency lunar escape to orbit using several simplified manual guidance and control techniques

NASA Technical Reports Server (NTRS)

Middleton, D. B.; Hurt, G. J., Jr.

1971-01-01

A fixed-base piloted simulator investigation has been made of the feasibility of using any of several manual guidance and control techniques for emergency lunar escape to orbit with very simplified, lightweight vehicle systems. The escape-to-orbit vehicles accommodate two men, but one man performs all of the guidance and control functions. Three basic attitude-control modes and four manually executed trajectory-guidance schemes were used successfully during approximately 125 simulated flights under a variety of conditions. These conditions included thrust misalinement, uneven propellant drain, and a vehicle moment-of-inertia range of 250 to 12,000 slugs per square foot. Two types of results are presented - orbit characteristics and pilot ratings of vehicle handling qualities.

Fast Orientation of Video Images of Buildings Acquired from a UAV without Stabilization.

PubMed

Kedzierski, Michal; Delis, Paulina

2016-06-23

The aim of this research was to assess the possibility of conducting an absolute orientation procedure for video imagery, in which the external orientation for the first image was typical for aerial photogrammetry whereas the external orientation of the second was typical for terrestrial photogrammetry. Starting from the collinearity equations, assuming that the camera tilt angle is equal to 90°, a simplified mathematical model is proposed. The proposed method can be used to determine the X, Y, Z coordinates of points based on a set of collinearity equations of a pair of images. The use of simplified collinearity equations can considerably shorten the processing tine of image data from Unmanned Aerial Vehicles (UAVs), especially in low cost systems. The conducted experiments have shown that it is possible to carry out a complete photogrammetric project of an architectural structure using a camera tilted 85°-90° ( φ or ω) and simplified collinearity equations. It is also concluded that there is a correlation between the speed of the UAV and the discrepancy between the established and actual camera tilt angles.

Fast Orientation of Video Images of Buildings Acquired from a UAV without Stabilization

PubMed Central

Kedzierski, Michal; Delis, Paulina

2016-01-01

The aim of this research was to assess the possibility of conducting an absolute orientation procedure for video imagery, in which the external orientation for the first image was typical for aerial photogrammetry whereas the external orientation of the second was typical for terrestrial photogrammetry. Starting from the collinearity equations, assuming that the camera tilt angle is equal to 90°, a simplified mathematical model is proposed. The proposed method can be used to determine the X, Y, Z coordinates of points based on a set of collinearity equations of a pair of images. The use of simplified collinearity equations can considerably shorten the processing tine of image data from Unmanned Aerial Vehicles (UAVs), especially in low cost systems. The conducted experiments have shown that it is possible to carry out a complete photogrammetric project of an architectural structure using a camera tilted 85°–90° (φ or ω) and simplified collinearity equations. It is also concluded that there is a correlation between the speed of the UAV and the discrepancy between the established and actual camera tilt angles. PMID:27347954

Tire-rim interface pressure of a commercial vehicle wheel under radial loads: theory and experiment

NASA Astrophysics Data System (ADS)

Wan, Xiaofei; Shan, Yingchun; Liu, Xiandong; He, Tian; Wang, Jiegong

2017-11-01

The simulation of the radial fatigue test of a wheel has been a necessary tool to improve the design of the wheel and calculate its fatigue life. The simulation model, including the strong nonlinearity of the tire structure and material, may produce accurate results, but often leads to a divergence in calculation. Thus, a simplified simulation model in which the complicated tire model is replaced with a tire-wheel contact pressure model is used extensively in the industry. In this paper, a simplified tire-rim interface pressure model of a wheel under a radial load is established, and the pressure of the wheel under different radial loads is tested. The tire-rim contact behavior affected by the radial load is studied and analyzed according to the test result, and the tire-rim interface pressure extracted from the test result is used to evaluate the simplified pressure model and the traditional cosine function model. The results show that the proposed model may provide a more accurate prediction of the wheel radial fatigue life than the traditional cosine function model.

Large deflections and vibrations of a tip pulled beam with variable transversal section

NASA Astrophysics Data System (ADS)

Kurka, P.; Izuka, J.; Gonzalez, P.; Teixeira, L. H.

2016-10-01

The use of long flexible probes in outdoors exploration vehicles, as opposed to short and rigid arms, is a convenient way to grant easier access to regions of scientific interest such as terrain slopes and cliff sides. Longer and taller arms can also provide information from a wider exploration horizon. The drawback of employing long and flexible exploration probes is the fact that its vibration is not easily controlled in real time operation by means of a simple analytic linear dynamic model. The numerical model required to describe the dynamics of a very long and flexible structure is often very large and of slow computational convergence. The present work proposes a simplified numerical model of a long flexible beam with variable cross section, which is statically deflected by a pulling cable. The paper compares the proposed simplified model with experimental data regarding the static and dynamic characteristics of a beam with variable cross section. The simulations show the effectiveness of the simplified dynamic model employed in an active control loop to suppress tip vibrations of the beam.

Blood flow mechanics and oxygen transport and delivery in the retinal microcirculation: multiscale mathematical modeling and numerical simulation.

PubMed

Causin, Paola; Guidoboni, Giovanna; Malgaroli, Francesca; Sacco, Riccardo; Harris, Alon

2016-06-01

The scientific community continues to accrue evidence that blood flow alterations and ischemic conditions in the retina play an important role in the pathogenesis of ocular diseases. Many factors influence retinal hemodynamics and tissue oxygenation, including blood pressure, blood rheology, oxygen arterial permeability and tissue metabolic demand. Since the influence of these factors on the retinal circulation is difficult to isolate in vivo, we propose here a novel mathematical and computational model describing the coupling between blood flow mechanics and oxygen ([Formula: see text]) transport in the retina. Albeit in a simplified manner, the model accounts for the three-dimensional anatomical structure of the retina, consisting in a layered tissue nourished by an arteriolar/venular network laying on the surface proximal to the vitreous. Capillary plexi, originating from terminal arterioles and converging into smaller venules, are embedded in two distinct tissue layers. Arteriolar and venular networks are represented by fractal trees, whereas capillary plexi are represented using a simplified lumped description. In the model, [Formula: see text] is transported along the vasculature and delivered to the tissue at a rate that depends on the metabolic demand of the various tissue layers. First, the model is validated against available experimental results to identify baseline conditions. Then, a sensitivity analysis is performed to quantify the influence of blood pressure, blood rheology, oxygen arterial permeability and tissue oxygen demand on the [Formula: see text] distribution within the blood vessels and in the tissue. This analysis shows that: (1) systemic arterial blood pressure has a strong influence on the [Formula: see text] profiles in both blood and tissue; (2) plasma viscosity and metabolic consumption rates have a strong influence on the [Formula: see text] tension at the level of the retinal ganglion cells; and (3) arterial [Formula: see text] permeability has a strong influence on the [Formula: see text] saturation in the retinal arterioles.

Impact of cell size on inventory and mapping errors in a cellular geographic information system

NASA Technical Reports Server (NTRS)

Wehde, M. E. (Principal Investigator)

1979-01-01

The author has identified the following significant results. The effect of grid position was found insignificant for maps but highly significant for isolated mapping units. A modelable relationship between mapping error and cell size was observed for the map segment analyzed. Map data structure was also analyzed with an interboundary distance distribution approach. Map data structure and the impact of cell size on that structure were observed. The existence of a model allowing prediction of mapping error based on map structure was hypothesized and two generations of models were tested under simplifying assumptions.

Thermal Characterization and Flammability of Structural Epoxy Adhesive and Carbon/Epoxy Composite with Environmental and Chemical Degradation (Postprint)

DTIC Science & Technology

2012-01-01

this study). TGA scans show the thermal degradation of carbon/ epoxy composite by fuel additive at room temperature. Through Microscale Combustion...concerns regarding the durability of structural epoxy adhesive contaminated by hydraulic fluid or fuel additive , under simplified test conditions (no...higher than room tem- perature) or fuel additive (at all temperatures of this study). TGA scans show the thermal degradation of carbon/ epoxy composite

Pitch-based carbon foam and composites

DOEpatents

Klett, James W.

2001-01-01

A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

Pitch-based carbon foam and composites

DOEpatents

Klett, James W.

2003-12-16

A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

Pitch-based carbon foam and composites

DOEpatents

Klett, James W.

2003-12-02

A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

Pitch-based carbon foam and composites

DOEpatents

Klett, James W.

2002-01-01

A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

A simplified experimental model for clearance of some pathogenic bacteria using common bacterivorous ciliated spp. in Tigris river

NASA Astrophysics Data System (ADS)

Ali, Talib Hassan; Saleh, Dhuha Saad

2014-03-01

Bacteria-specific uptake rates of three different protozoan taxa on a pure and mixed bacterial community was studied by means of a simplified and functionally reproducible experimental model. The bacterial species Shigella flexneri, Escherichia coli and Salmonella typhi were isolated and classified from stool samples of patients suffering from diarrhea. Paramecium caudatum, Tetrahymena pyriformis and Halteria grandinella, free living ciliate Protozoans, were isolated and identified from Tigris river water. Pure and mixed ( E. coli + S. typhi), ( E. coli + Sh. flexneri) bacterial cultures were used with each ciliate genera to evaluate the following: predator duplication rate, prey reduction rate, clearance rate and net grazing rate. We used selective lactose fermentation phenomena of enteric bacteria on MacConkey medium for the quantification of bacteria cultural characteristics. The final bacteria concentration was reduced by growing protozoa of 98-99.9 % compared to protozoa-free controls. It showed that Tetrahymena pyriformis had the highest duplication rate (4.13 time/day) in both types of cultures (pure and mixed), followed by Paramecium caudatum and Halteria grandinella, respectively. Paramecium caudatum had the highest rate of ingestion in both types of cultures (26 × 103 bacteria/organism/hr) and yielded the longest time required for 90 % bacterial reduction in a pure suspension of S. typhi (166 h). Clearance rates of pathogenic bacteria by ciliates ranged between 106 nanoliter/organism/h by P. caudatum to S. typhi and 1.92 nanoliter/organism/h seen in T. pyriformis in ( E. coli + S. typhi) mixed culture. We used aquatic experimental microcosms under controlled conditions to explore bacteria-dependent ciliate growth and examined whether these ciliates could discriminate between equally sized bacterial preys in a mixture.

Corrosion detection and evolution monitoring in reinforced concrete structures by the use of fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Ali-Alvarez, S.; Ferdinand, P.; Magne, S.; Nogueira, R. P.

2013-04-01

Corrosion of reinforced bar (rebar) in concrete structures represents a major issue in civil engineering works, being its detection and evolution a challenge for the applied research. In this work, we present a new methodology to corrosion detection in reinforced concrete structures, by combining Fiber Bragg Grating (FBG) sensors with the electrochemical and physical properties of rebar in a simplified assembly. Tests in electrolytic solutions and concrete were performed for pitting and general corrosion. The proposed Structural Health Monitoring (SHM) methodology constitutes a direct corrosion measurement potentially useful to implement or improve Condition-Based Maintenance (CBM) program for civil engineering concrete structures.

Entropy reduction via simplified image contourization

NASA Technical Reports Server (NTRS)

Turner, Martin J.

1993-01-01

The process of contourization is presented which converts a raster image into a set of plateaux or contours. These contours can be grouped into a hierarchical structure, defining total spatial inclusion, called a contour tree. A contour coder has been developed which fully describes these contours in a compact and efficient manner and is the basis for an image compression method. Simplification of the contour tree has been undertaken by merging contour tree nodes thus lowering the contour tree's entropy. This can be exploited by the contour coder to increase the image compression ratio. By applying general and simple rules derived from physiological experiments on the human vision system, lossy image compression can be achieved which minimizes noticeable artifacts in the simplified image.

The role of boundary variability in polycrystalline grain-boundary diffusion

NASA Astrophysics Data System (ADS)

Moghadam, M. M.; Rickman, J. M.; Harmer, M. P.; Chan, H. M.

2015-01-01

We investigate the impact of grain-boundary variability on mass transport in a polycrystal. More specifically, we perform both numerical and analytical studies of steady-state diffusion in prototypical microstructures in which there is either a discrete spectrum of grain-boundary activation energies or else a complex distribution of grain-boundary character, and hence a continuous spectrum of boundary activation energies. An effective diffusivity is calculated for these structures using simplified multi-state models and, for the case of a continuous spectrum, employing experimentally obtained grain-boundary energy data. We identify different diffusive regimes for these cases and quantify deviations from Arrhenius behavior using effective medium theory. Finally, we examine the diffusion kinetics of a simplified model of an interfacial layering (i.e., complexion) transition.

Advances in bioanalytical techniques to measure steroid hormones in serum.

PubMed

French, Deborah

2016-06-01

Steroid hormones are measured clinically to determine if a patient has a pathological process occurring in the adrenal gland, or other hormone responsive organs. They are very similar in structure making them analytically challenging to measure. Additionally, these hormones have vast concentration differences in human serum adding to the measurement complexity. GC-MS was the gold standard methodology used to measure steroid hormones clinically, followed by radioimmunoassay, but that was replaced by immunoassay due to ease of use. LC-MS/MS has now become a popular alternative owing to simplified sample preparation than for GC-MS and increased specificity and sensitivity over immunoassay. This review will discuss these methodologies and some new developments that could simplify and improve steroid hormone analysis in serum.

Simplified Technique for Predicting Offshore Pipeline Expansion

NASA Astrophysics Data System (ADS)

Seo, J. H.; Kim, D. K.; Choi, H. S.; Yu, S. Y.; Park, K. S.

2018-06-01

In this study, we propose a method for estimating the amount of expansion that occurs in subsea pipelines, which could be applied in the design of robust structures that transport oil and gas from offshore wells. We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines. Due to the effects of high pressure and high temperature, the production of fluid from offshore wells is typically caused by physical deformation of subsea structures, e.g., expansion and contraction during the transportation process. In severe cases, vertical and lateral buckling occurs, which causes a significant negative impact on structural safety, and which is related to on-bottom stability, free-span, structural collapse, and many other factors. In addition, these factors may affect the production rate with respect to flow assurance, wax, and hydration, to name a few. In this study, we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage, which can lead to savings in both cost and computation time. As such, in this paper, we propose an applicable diagram, which we call the standard dimensionless ratio (SDR) versus virtual anchor length (L A ) diagram, that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios. With this user guideline, offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation, design, and maintenance of the subsea pipeline.

"Starfish" Heater Head For Stirling Engine

NASA Technical Reports Server (NTRS)

Vitale, N.

1993-01-01

Proposed "starfish" heater head for Stirling engine enables safe use of liquid sodium as heat-transfer fluid. Sodium makes direct contact with heater head but does not come in contact with any structural welds. Design concept minimizes number of, and simplifies nonstructural thermal welds and facilitates inspection of such welds.

Vibrations and structureborne noise in space station

NASA Technical Reports Server (NTRS)

Vaicaitis, R.

1985-01-01

The related literature was reviewed and a preliminary analytical model was developed for simplified acoustic and structural geometries for pressurized and unpressurized space station modules. In addition to the analytical work, an experimental program on structureborne noise generation and transmission was started. A brief review of those accomplishments is given.

Simplified Techniques for Evaluation and Interpretation of Pavement Deflections for Network-level Analysis : Guide for Assessment of Pavement Structure Performance for PMS Applications

DOT National Transportation Integrated Search

2012-06-01

The objective of this study was to develop an approach for incorporating techniques to interpret and evaluate deflection : data for network-level pavement management system (PMS) applications. The first part of this research focused on : identifying ...

An Analysis of the Effect of Knowledge Management on the Execution of Simplified Acquisition Procedures

DTIC Science & Technology

2012-12-27

of Work UCC Uniform Commercial Code USD(AT&L) Under Secretary of Defense for Acquisition, Technology, and Logistics WBS Work Breakdown Structure...intensive career field. The FAR, the DFARS, and other federal agency supplements of the FAR, the Uniform Commercial Code ( UCC ), installation guidelines

Factor Structure of the Chinese Virtues Questionnaire

ERIC Educational Resources Information Center

Duan, Wenjie; Ho, Samuel M. Y.; Yu, Bai; Tang, Xiaoqing; Zhang, Yonghong; Li, Tingting; Yuen, Tom

2012-01-01

Objectives: The present study examined the factorial invariance and functional equivalence of the Values in Action Inventory of Strengths (VIA-IS) among the Chinese. Methods: A total of 839 undergraduate students completed the 240-item Simplified Chinese version of the VIA-IS online. Another 40 students participated in qualitative interviews to…

The German Passive: Analysis and Teaching Technique.

ERIC Educational Resources Information Center

Griffen, T. D.

1981-01-01

Proposes an analysis of German passive based upon internal structure rather than translation conventions from Latin and Greek. Claims that this approach leads to a description of the perfect participle as an adjectival complement, which eliminates the classification of a passive voice for German and simplifies the learning task. (MES)

A vegetation classification system for use in California: its conceptual basis

Treesearch

Timothy E. Paysen; Jeanine A. Derby; C. Eugene Conrad

1982-01-01

A taxonomic Vegetation Classification System proposed for use in California is designed to simplify interdisciplinary communication about vegetation. The system structure is an aggregative plant community hierarchy at four levels of precision--the Association, Series, Subformation, and Formation. A flexible Phase category links specific resource management concerns to...

SMOKE TOOL FOR MODELS-3 VERSION 4.1 STRUCTURE AND OPERATION DOCUMENTATION

EPA Science Inventory

The SMOKE Tool is a part of the Models-3 system, a flexible software system designed to simplify the development and use of air quality models and other environmental decision support tools. The SMOKE Tool is an input processor for SMOKE, (Sparse Matrix Operator Kernel Emissio...

Fundamental structure of steady plastic shock waves in metals

NASA Astrophysics Data System (ADS)

Molinari, A.; Ravichandran, G.

2004-02-01

The propagation of steady plane shock waves in metallic materials is considered. Following the constitutive framework adopted by R. J. Clifton [Shock Waves and the Mechanical Properties of Solids, edited by J. J. Burke and V. Weiss (Syracuse University Press, Syracuse, N.Y., 1971), p. 73] for analyzing elastic-plastic transient waves, an analytical solution of the steady state propagation of plastic shocks is proposed. The problem is formulated in a Lagrangian setting appropriate for large deformations. The material response is characterized by a quasistatic tensile (compression) test (providing the isothermal strain hardening law). In addition the elastic response is determined up to second order elastic constants by ultrasonic measurements. Based on this simple information, it is shown that the shock kinetics can be quite well described for moderate shocks in aluminum with stress amplitude up to 10 GPa. Under the later assumption, the elastic response is assumed to be isentropic, and thermomechanical coupling is neglected. The model material considered here is aluminum, but the analysis is general and can be applied to any viscoplastic material subjected to moderate amplitude shocks. Comparisons with experimental data are made for the shock velocity, the particle velocity and the shock structure. The shock structure is obtained by quadrature of a first order differential equation, which provides analytical results under certain simplifying assumptions. The effects of material parameters and loading conditions on the shock kinetics and shock structure are discussed. The shock width is characterized by assuming an overstress formulation for the viscoplastic response. The effects on the shock structure of strain rate sensitivity are analyzed and the rationale for the J. W. Swegle and D. E. Grady [J. Appl. Phys. 58, 692 (1985)] universal scaling law for homogeneous materials is explored. Finally, the ability to deduce information on the viscoplastic response of materials subjected to very high strain rates from shock wave experiments is discussed.

Tectolinear interpretation of a 1:5,000,000 Landsat-1 mosaic compared with the structure of central and eastern United States

USGS Publications Warehouse

Kutina, Jan; Carter, William D.

1978-01-01

The pattern of lineaments and curvilinear features interpreted from a 1:5,000,000 mosaic of satellite images (Landsat-1 was superimposed on a simplified version of the Geological Map of the United States, 1:2,500,000 scale, showing the structural scheme of Central and Eastern United States. A comparison of the above two patterns, shown in Fig. 1, is presented in this paper.

Tick off to Take off: The Pre-Departure Guide

ERIC Educational Resources Information Center

Arthur, Erica

2009-01-01

"Tick Off to Take Off (TOTTO)" is an online pre-departure guide for UK undergraduates intending to study abroad. It aims to simplify the application process, centralise information, increase efficiency and improve retention rates. TOTTO responds to the changing climate surrounding study abroad in UK universities and offers one way to…

Theoretical characterization of photoinduced electron transfer in rigidly linked donor-acceptor molecules: the fragment charge difference and the generalized Mulliken-Hush schemes

NASA Astrophysics Data System (ADS)

Lee, Sheng-Jui; Chen, Hung-Cheng; You, Zhi-Qiang; Liu, Kuan-Lin; Chow, Tahsin J.; Chen, I.-Chia; Hsu, Chao-Ping

2010-10-01

We calculate the electron transfer (ET) rates for a series of heptacyclo[6.6.0.02,6.03,13.014,11.05,9.010,14]-tetradecane (HCTD) linked donor-acceptor molecules. The electronic coupling factor was calculated by the fragment charge difference (FCD) [19] and the generalized Mulliken-Hush (GMH) schemes [20]. We found that the FCD is less prone to problems commonly seen in the GMH scheme, especially when the coupling values are small. For a 3-state case where the charge transfer (CT) state is coupled with two different locally excited (LE) states, we tested with the 3-state approach for the GMH scheme [30], and found that it works well with the FCD scheme. A simplified direct diagonalization based on Rust's 3-state scheme was also proposed and tested. This simplified scheme does not require a manual assignment of the states, and it yields coupling values that are largely similar to those from the full Rust's approach. The overall electron transfer (ET) coupling rates were also calculated.

Computational modeling of the pressurization process in a NASP vehicle propellant tank experimental simulation

NASA Technical Reports Server (NTRS)

Sasmal, G. P.; Hochstein, J. I.; Wendl, M. C.; Hardy, T. L.

1991-01-01

A multidimensional computational model of the pressurization process in a slush hydrogen propellant storage tank was developed and its accuracy evaluated by comparison to experimental data measured for a 5 ft diameter spherical tank. The fluid mechanic, thermodynamic, and heat transfer processes within the ullage are represented by a finite-volume model. The model was shown to be in reasonable agreement with the experiment data. A parameter study was undertaken to examine the dependence of the pressurization process on initial ullage temperature distribution and pressurant mass flow rate. It is shown that for a given heat flux rate at the ullage boundary, the pressurization process is nearly independent of initial temperature distribution. Significant differences were identified between the ullage temperature and velocity fields predicted for pressurization of slush and those predicted for pressurization of liquid hydrogen. A simplified model of the pressurization process was constructed in search of a dimensionless characterization of the pressurization process. It is shown that the relationship derived from this simplified model collapses all of the pressure history data generated during this study into a single curve.

Flow resistance and suspended load in sand-bed rivers: Simplified stratification model

USGS Publications Warehouse

Wright, S.; Parker, G.

2004-01-01

New methods are presented for the prediction of the flow depth, grain-size specific near-bed concentration, and bed-material suspended sediment transport rate in sand-bed rivers. The salient improvements delineated here all relate to the need to modify existing formulations in order to encompass the full range of sand-bed rivers, and in particular large, low-slope sand-bed rivers. They can be summarized as follows: (1) the inclusion of density stratification effects in a simplified manner, which have been shown in the companion paper to be particularly relevant for large, low-slope, sand-bed rivers; (2) a new predictor for near-bed entrainment rate into suspension which extends a previous relation to the range of large, low-slope sand-bed rivers; and (3) a new predictor for form drag which again extends a previous relation to include large, low-slope sand-bed rivers. Finally, every attempt has been made to cast the relations in the simplest form possible, including the development of software, so that practicing engineers may easily use the methods. ?? ASCE.

Color and Vector Flow Imaging in Parallel Ultrasound With Sub-Nyquist Sampling.

PubMed

Madiena, Craig; Faurie, Julia; Poree, Jonathan; Garcia, Damien; Garcia, Damien; Madiena, Craig; Faurie, Julia; Poree, Jonathan

2018-05-01

RF acquisition with a high-performance multichannel ultrasound system generates massive data sets in short periods of time, especially in "ultrafast" ultrasound when digital receive beamforming is required. Sampling at a rate four times the carrier frequency is the standard procedure since this rule complies with the Nyquist-Shannon sampling theorem and simplifies quadrature sampling. Bandpass sampling (or undersampling) outputs a bandpass signal at a rate lower than the maximal frequency without harmful aliasing. Advantages over Nyquist sampling are reduced storage volumes and data workflow, and simplified digital signal processing tasks. We used RF undersampling in color flow imaging (CFI) and vector flow imaging (VFI) to decrease data volume significantly (factor of 3 to 13 in our configurations). CFI and VFI with Nyquist and sub-Nyquist samplings were compared in vitro and in vivo. The estimate errors due to undersampling were small or marginal, which illustrates that Doppler and vector Doppler images can be correctly computed with a drastically reduced amount of RF samples. Undersampling can be a method of choice in CFI and VFI to avoid information overload and reduce data transfer and storage.

Artificial Aging Effects on Cryogenic Fracture Toughness of the Main Structural Alloy for the Super Lightweight Tank

NASA Technical Reports Server (NTRS)

Chen, P. S.; Stanton, W. P.

2002-01-01

In 1996, Marshall Space Flight Center developed a multistep heating rate-controlled (MSRC) aging technique that significantly enhanced cryogenic fracture toughness (CFT) and reduced the statistical spread of fracture toughness values in alloy 2195 by controlling the location and size of strengthening precipitate T1. However, it could not be readily applied to flight-related hardware production, primarily because large-scale production furnaces are unable to maintain a heating rate of 0.6 C (1 F)/hr. In August 1996, a new program was initiated to determine whether the MSRC aging treatment could be further modified to facilitate its implementation to flight hardware production. It was successfully redesigned into a simplified two-step aging treatment consisting of 132 C (270 F)/20 hr + 138 C (280 F)/40 hr. Results indicated that two-step aging can achieve the same yield strength levels as those produced by conventional aging while providing greatly improved ductility. Two-step aging proved to be very effective at enhancing CFT, enabling previously rejected materials to meet simulated service requirements. Cryogenic properties are improved by controlling T1 nucleation and growth so that they are promoted in the matrix and suppressed in the subgrain boundaries.

Theoretical and Experimental Study of Radial Velocity Generation for Extending Bandwidth of Magnetohydrodynamic Angular Rate Sensor at Low Frequency.

PubMed

Ji, Yue; Li, Xingfei; Wu, Tengfei; Chen, Cheng

2015-12-15

The magnetohydrodynamics angular rate sensor (MHD ARS) has received much attention for its ultra-low noise in ultra-broad bandwidth and its impact resistance in harsh environments; however, its poor performance at low frequency hinders its work in long time duration. The paper presents a modified MHD ARS combining Coriolis with MHD effect to extend the measurement scope throughout the whole bandwidth, in which an appropriate radial flow velocity should be provided to satisfy simplified model of the modified MHD ARS. A method that can generate radial velocity by an MHD pump in MHD ARS is proposed. A device is designed to study the radial flow velocity generated by the MHD pump. The influence of structure and physical parameters are studied by numerical simulation and experiment of the device. The analytic expression of the velocity generated by the energized current drawn from simulation and experiment are consistent, which demonstrates the effectiveness of the method generating radial velocity. The study can be applied to generate and control radial velocity in modified MHD ARS, which is essential for the two effects combination throughout the whole bandwidth.

Theoretical and Experimental Study of Radial Velocity Generation for Extending Bandwidth of Magnetohydrodynamic Angular Rate Sensor at Low Frequency

PubMed Central

Ji, Yue; Li, Xingfei; Wu, Tengfei; Chen, Cheng

2015-01-01

The magnetohydrodynamics angular rate sensor (MHD ARS) has received much attention for its ultra-low noise in ultra-broad bandwidth and its impact resistance in harsh environments; however, its poor performance at low frequency hinders its work in long time duration. The paper presents a modified MHD ARS combining Coriolis with MHD effect to extend the measurement scope throughout the whole bandwidth, in which an appropriate radial flow velocity should be provided to satisfy simplified model of the modified MHD ARS. A method that can generate radial velocity by an MHD pump in MHD ARS is proposed. A device is designed to study the radial flow velocity generated by the MHD pump. The influence of structure and physical parameters are studied by numerical simulation and experiment of the device. The analytic expression of the velocity generated by the energized current drawn from simulation and experiment are consistent, which demonstrates the effectiveness of the method generating radial velocity. The study can be applied to generate and control radial velocity in modified MHD ARS, which is essential for the two effects combination throughout the whole bandwidth. PMID:26694393

A semi-phenomenological model to predict the acoustic behavior of fully and partially reticulated polyurethane foams

NASA Astrophysics Data System (ADS)

Doutres, Olivier; Atalla, Noureddine; Dong, Kevin

2013-02-01

This paper proposes simple semi-phenomenological models to predict the sound absorption efficiency of highly porous polyurethane foams from microstructure characterization. In a previous paper [J. Appl. Phys. 110, 064901 (2011)], the authors presented a 3-parameter semi-phenomenological model linking the microstructure properties of fully and partially reticulated isotropic polyurethane foams (i.e., strut length l, strut thickness t, and reticulation rate Rw) to the macroscopic non-acoustic parameters involved in the classical Johnson-Champoux-Allard model (i.e., porosity ϕ, airflow resistivity σ, tortuosity α∝, viscous Λ, and thermal Λ' characteristic lengths). The model was based on existing scaling laws, validated for fully reticulated polyurethane foams, and improved using both geometrical and empirical approaches to account for the presence of membrane closing the pores. This 3-parameter model is applied to six polyurethane foams in this paper and is found highly sensitive to the microstructure characterization; particularly to strut's dimensions. A simplified micro-/macro model is then presented. It is based on the cell size Cs and reticulation rate Rw only, assuming that the geometric ratio between strut length l and strut thickness t is known. This simplified model, called the 2-parameter model, considerably simplifies the microstructure characterization procedure. A comparison of the two proposed semi-phenomenological models is presented using six polyurethane foams being either fully or partially reticulated, isotropic or anisotropic. It is shown that the 2-parameter model is less sensitive to measurement uncertainties compared to the original model and allows a better estimation of polyurethane foams sound absorption behavior.

Rubble masonry response under cyclic actions: The experience of L’Aquila city (Italy)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fonti, Roberta, E-mail: roberta.fonti@tum.de; Barthel, Rainer, E-mail: r.barthel@lrz.tu-muenchen.de; Formisano, Antonio, E-mail: antoform@unina.it

2015-12-31

Several methods of analysis are available in engineering practice to study old masonry constructions. Two commonly used approaches in the field of seismic engineering are global and local analyses. Despite several years of research in this field, the various methodologies suffer from a lack of comprehensive experimental validation. This is mainly due to the difficulty in simulating the many different kinds of masonry and, accordingly, the non-linear response under horizontal actions. This issue can be addressed by examining the local response of isolated panels under monotonic and/or alternate actions. Different testing methodologies are commonly used to identify the local responsemore » of old masonry. These range from simplified pull-out tests to sophisticated in-plane monotonic tests. However, there is a lack of both knowledge and critical comparison between experimental validations and numerical simulations. This is mainly due to the difficulties in implementing irregular settings within both simplified and advanced numerical analyses. Similarly, the simulation of degradation effects within laboratory tests is difficult with respect to old masonry in-situ boundary conditions. Numerical models, particularly on rubble masonry, are commonly simplified. They are mainly based on a kinematic chain of rigid blocks able to perform different “modes of damage” of structures subjected to horizontal actions. This paper presents an innovative methodology for testing; its aim is to identify a simplified model for out-of-plane response of rubbleworks with respect to the experimental evidence. The case study of L’Aquila district is discussed.« less

Dissecting jets and missing energy searches using $n$-body extended simplified models

DOE PAGES

Cohen, Timothy; Dolan, Matthew J.; El Hedri, Sonia; ...

2016-08-04

Simplified Models are a useful way to characterize new physics scenarios for the LHC. Particle decays are often represented using non-renormalizable operators that involve the minimal number of fields required by symmetries. Generalizing to a wider class of decay operators allows one to model a variety of final states. This approach, which we dub the $n$-body extension of Simplified Models, provides a unifying treatment of the signal phase space resulting from a variety of signals. In this paper, we present the first application of this framework in the context of multijet plus missing energy searches. The main result of thismore » work is a global performance study with the goal of identifying which set of observables yields the best discriminating power against the largest Standard Model backgrounds for a wide range of signal jet multiplicities. Our analysis compares combinations of one, two and three variables, placing emphasis on the enhanced sensitivity gain resulting from non-trivial correlations. Utilizing boosted decision trees, we compare and classify the performance of missing energy, energy scale and energy structure observables. We demonstrate that including an observable from each of these three classes is required to achieve optimal performance. In conclusion, this work additionally serves to establish the utility of $n$-body extended Simplified Models as a diagnostic for unpacking the relative merits of different search strategies, thereby motivating their application to new physics signatures beyond jets and missing energy.« less

Application of the backstepping method to the prediction of increase or decrease of infected population.

PubMed

Kuniya, Toshikazu; Sano, Hideki

2016-05-10

In mathematical epidemiology, age-structured epidemic models have usually been formulated as the boundary-value problems of the partial differential equations. On the other hand, in engineering, the backstepping method has recently been developed and widely studied by many authors. Using the backstepping method, we obtained a boundary feedback control which plays the role of the threshold criteria for the prediction of increase or decrease of newly infected population. Under an assumption that the period of infectiousness is same for all infected individuals (that is, the recovery rate is given by the Dirac delta function multiplied by a sufficiently large positive constant), the prediction method is simplified to the comparison of the numbers of reported cases at the current and previous time steps. Our prediction method was applied to the reported cases per sentinel of influenza in Japan from 2006 to 2015 and its accuracy was 0.81 (404 correct predictions to the total 500 predictions). It was higher than that of the ARIMA models with different orders of the autoregressive part, differencing and moving-average process. In addition, a proposed method for the estimation of the number of reported cases, which is consistent with our prediction method, was better than that of the best-fitted ARIMA model ARIMA(1,1,0) in the sense of mean square error. Our prediction method based on the backstepping method can be simplified to the comparison of the numbers of reported cases of the current and previous time steps. In spite of its simplicity, it can provide a good prediction for the spread of influenza in Japan.

Evaluation of Silicon-on-Insulator HTOP-01 Operational Amplifier for Wide Temperature Operation

NASA Technical Reports Server (NTRS)

Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

2008-01-01

Electronics capable of operation under extreme temperatures are required in many of NASA space exploration missions. Aerospace and military applications, as well as some terrestrial industries constitute environments where electronic systems are anticipated to be exposed to extreme temperatures and wide-range thermal swings. Electronics that are able to withstand and operate efficiently in such harsh environments would simplify, if not eliminate, traditional thermal control elements and their associated structures for proper ambient operation. As a result, overall system mass would be reduced, design would be simplified, and reliability would be improved. Electronic parts that are built utilizing silicon-on-insulator (SOI) technology are known to offer better radiation-tolerance compared to their conventional silicon counterparts, provide faster switching, and consume less power. They also exhibit reduced leakage current and, thus, they are often tailored for high temperature operation. These attributes make SOI-based devices suitable for use in harsh environments where extreme temperatures and wide thermal swings are anticipated. A new operational amplifier, based on silicon-on-insulator technology and geared for high temperature well-logging applications, was recently introduced by Honeywell Corporation. This HTOP-01 dual precision operational amplifier is a low power device, operates on a single supply, and has an internal oscillator and an external clocking option [1]. It is rated for operation from -55 C to +225 C with a maximum output current capability of 50 mA. The amplifier chip is designed as a 14-pin, hermetically-sealed device in a ceramic package. Table I shows some of the device manufacturer s specifications.

Biomethanation under psychrophilic conditions.

PubMed

Dhaked, Ram Kumar; Singh, Padma; Singh, Lokendra

2010-12-01

The biomethanation of organic matter represents a long-standing, well-established technology. Although at mesophilic and thermophilic temperatures the process is well understood, current knowledge on psychrophilic biomethanation is somewhat scarce. Methanogenesis is particularly sensitive to temperature, which not only affects the activity and structure of the microbial community, but also results in a change in the degradation pathway of organic matter. There is evidence of psychrophilic methanogenesis in natural environments, and a number of methanogenic archaea have been isolated with optimum growth temperatures of 15-25 °C. At psychrophilic temperatures, large amounts of heat are needed to operate reactors, thus resulting in a marginal or negative overall energy yield. Biomethanation at ambient temperature can alleviate this requirement, but for stable biogas production, a microbial consortium adapted to low temperatures or a psychrophilic consortium is required. Single-step or two-step high rate anaerobic reactors [expanded granular sludge bed (EGSB) and up flow anaerobic sludge bed (UASB)] have been used for the treatment of low strength wastewater. Simplified versions of these reactors, such as anaerobic sequencing batch reactors (ASBR) and anaerobic migrating blanket reactor (AMBR) have also been developed with the aim of reducing volume and cost. This technology has been further simplified and extended for the disposal of night soil in high altitude, low temperature areas of the Himalayas, where the hilly terrain, non-availability of conventional energy, harsh climate and space constraints limit the application of complicated reactors. Biomethanation at psychrophilic temperatures and the contribution made to night-soil degradation in the Himalayas are reviewed in this article. Copyright © 2010 Elsevier Ltd. All rights reserved.

Soft-output decoding algorithms in iterative decoding of turbo codes

NASA Technical Reports Server (NTRS)

Benedetto, S.; Montorsi, G.; Divsalar, D.; Pollara, F.

1996-01-01

In this article, we present two versions of a simplified maximum a posteriori decoding algorithm. The algorithms work in a sliding window form, like the Viterbi algorithm, and can thus be used to decode continuously transmitted sequences obtained by parallel concatenated codes, without requiring code trellis termination. A heuristic explanation is also given of how to embed the maximum a posteriori algorithms into the iterative decoding of parallel concatenated codes (turbo codes). The performances of the two algorithms are compared on the basis of a powerful rate 1/3 parallel concatenated code. Basic circuits to implement the simplified a posteriori decoding algorithm using lookup tables, and two further approximations (linear and threshold), with a very small penalty, to eliminate the need for lookup tables are proposed.

A Simplified GCS-DCSK Modulation and Its Performance Optimization

NASA Astrophysics Data System (ADS)

Xu, Weikai; Wang, Lin; Chi, Chong-Yung

2016-12-01

In this paper, a simplified Generalized Code-Shifted Differential Chaos Shift Keying (GCS-DCSK) whose transmitter never needs any delay circuits, is proposed. However, its performance is deteriorated because the orthogonality between substreams cannot be guaranteed. In order to optimize its performance, the system model of the proposed GCS-DCSK with power allocations on substreams is presented. An approximate bit error rate (BER) expression of the proposed model, which is a function of substreams’ power, is derived using Gaussian Approximation. Based on the BER expression, an optimal power allocation strategy between information substreams and reference substream is obtained. Simulation results show that the BER performance of the proposed GCS-DCSK with the optimal power allocation can be significantly improved when the number of substreams M is large.

Reflector and Protections in a Sodium-cooled Fast Reactor: Modelling and Optimization

NASA Astrophysics Data System (ADS)

Blanchet, David; Fontaine, Bruno

2017-09-01

The ASTRID project (Advanced Sodium Technological Reactor for Industrial Demonstration) is a Generation IV nuclear reactor concept under development in France [1]. In this frame, studies are underway to optimize radial reflectors and protections. Considering radial protections made in natural boron carbide, this study is conducted to assess the neutronic performances of the MgO as the reference choice for reflector material, in comparison with other possible materials including a more conventional stainless steel. The analysis is based upon a simplified 1-D and 2-D deterministic modelling of the reactor, providing simplified interfaces between core, reflector and protections. Such models allow examining detailed reaction rate distributions; they also provide physical insights into local spectral effects occurring at the Core-Reflector and at the Reflector-Protection interfaces.

Uncertainty about fundamentals and herding behavior in the FOREX market

NASA Astrophysics Data System (ADS)

Kaltwasser, Pablo Rovira

2010-03-01

It is traditionally assumed in finance models that the fundamental value of assets is known with certainty. Although this is an appealing simplifying assumption it is by no means based on empirical evidence. A simple heterogeneous agent model of the exchange rate is presented. In the model, traders do not observe the true underlying fundamental exchange rate and as a consequence they base their trades on beliefs about this variable. Despite the fact that only fundamentalist traders operate in the market, the model belongs to the heterogeneous agent literature, as traders have different beliefs about the fundamental rate.

Solid motor aft closure insulation erosion. [heat flux correlation for rate analysis

NASA Technical Reports Server (NTRS)

Stampfl, E.; Landsbaum, E. M.

1973-01-01

The erosion rate of aft closure insulation in a number of large solid propellant motors was empirically analyzed by correlating the average ablation rate with a number of variables that had previously been demonstrated to affect heat flux. The main correlating parameter was a heat flux based on the simplified Bartz heat transfer coefficient corrected for two-dimensional effects. A multiplying group contained terms related to port-to-throat ratio, local wall angle, grain geometry and nozzle cant angle. The resulting equation gave a good correlation and is a useful design tool.

Simplification and Saving

PubMed Central

Beshears, John; Choi, James J.; Laibson, David; Madrian, Brigitte C.

2012-01-01

The daunting complexity of important financial decisions can lead to procrastination. We evaluate a low-cost intervention that substantially simplifies the retirement savings plan participation decision. Individuals received an opportunity to enroll in a retirement savings plan at a pre-selected contribution rate and asset allocation, allowing them to collapse a multidimensional problem into a binary choice between the status quo and the pre-selected alternative. The intervention increases plan enrollment rates by 10 to 20 percentage points. We find that a similar intervention can be used to increase contribution rates among employees who are already participating in a savings plan. PMID:24443619

TH-C-12A-04: Dosimetric Evaluation of a Modulated Arc Technique for Total Body Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsiamas, P; Czerminska, M; Makrigiorgos, G

2014-06-15

Purpose: A simplified Total Body Irradiation (TBI) was developed to work with minimal requirements in a compact linac room without custom motorized TBI couch. Results were compared to our existing fixed-gantry double 4 MV linac TBI system with prone patient and simultaneous AP/PA irradiation. Methods: Modulated arc irradiates patient positioned in prone/supine positions along the craniocaudal axis. A simplified inverse planning method developed to optimize dose rate as a function of gantry angle for various patient sizes without the need of graphical 3D treatment planning system. This method can be easily adapted and used with minimal resources. Fixed maximum fieldmore » size (40×40 cm2) is used to decrease radiation delivery time. Dose rate as a function of gantry angle is optimized to result in uniform dose inside rectangular phantoms of various sizes and a custom VMAT DICOM plans were generated using a DICOM editor tool. Monte Carlo simulations, film and ionization chamber dosimetry for various setups were used to derive and test an extended SSD beam model based on PDD/OAR profiles for Varian 6EX/ TX. Measurements were obtained using solid water phantoms. Dose rate modulation function was determined for various size patients (100cm − 200cm). Depending on the size of the patient arc range varied from 100° to 120°. Results: A PDD/OAR based beam model for modulated arc TBI therapy was developed. Lateral dose profiles produced were similar to profiles of our existing TBI facility. Calculated delivery time and full arc depended on the size of the patient (∼8min/ 100° − 10min/ 120°, 100 cGy). Dose heterogeneity varied by about ±5% − ±10% depending on the patient size and distance to the surface (buildup region). Conclusion: TBI using simplified modulated arc along craniocaudal axis of different size patients positioned on the floor can be achieved without graphical / inverse 3D planning.« less

Biomass-C specific temperature responses of microbial C transformations reveal consistency regardless of microbial community structure across diverse timescales of inquiry

NASA Astrophysics Data System (ADS)

Min, K.; Buckeridge, K. M.; Ziegler, S. E.; Edwards, K. A.; Bagchi, S.; Billings, S. A.

2016-12-01

The responses of heterotrophic microbial process rates to temperature in soils are often investigated in the short-term (hours to months), making it difficult to predict longer-term temperature responses. Here, we integrate the temperature sensitivity obtained from the Arrhenius model with the concepts of microbial resistance, resilience, and susceptibility to assess temporal dynamics of microbial temperature responses. We collected soils along a boreal forest climate gradient (long-term effect), and quantified exo-enzyme activities and CO2 respiration at 5, 15, and 25°C for 84 days (relatively short-term effect). Microbial process rates were examined at two levels (per g microbial biomass-C; and per g dry soil) along with community structure, to characterize driving mechanisms for temporal patterns (e.g., size of biomass, physiological plasticity, community composition). Although temperature sensitivity of exo-enzyme activities on a per g dry soil basis showed both resistance and resilience depending on the types of exo-enzyme, biomass -C-specific responses always exhibited resistance regardless of distinct community composition. Temperature sensitivity of CO2 respiration was constant across time and different communities at both units. This study advances our knowledge in two ways. First, resistant temperature sensitivity of exo-enzymes and respiration at biomass-C specific level across distinct communities and diverse timescales indicates a common relationship between microbial physiology and temperature at a fundamental level, a useful feature allowing microbial process models to be reasonably simplified. Second, different temporal responses of exo-enzymes depending on the unit selected provide a cautionary tale for those projecting future microbial behaviors, because interpretation of ecosystem process rates may vary with the unit of observation.

PWR Facility Dose Modeling Using MCNP5 and the CADIS/ADVANTG Variance-Reduction Methodology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blakeman, Edward D; Peplow, Douglas E.; Wagner, John C

2007-09-01

The feasibility of modeling a pressurized-water-reactor (PWR) facility and calculating dose rates at all locations within the containment and adjoining structures using MCNP5 with mesh tallies is presented. Calculations of dose rates resulting from neutron and photon sources from the reactor (operating and shut down for various periods) and the spent fuel pool, as well as for the photon source from the primary coolant loop, were all of interest. Identification of the PWR facility, development of the MCNP-based model and automation of the run process, calculation of the various sources, and development of methods for visually examining mesh tally filesmore » and extracting dose rates were all a significant part of the project. Advanced variance reduction, which was required because of the size of the model and the large amount of shielding, was performed via the CADIS/ADVANTG approach. This methodology uses an automatically generated three-dimensional discrete ordinates model to calculate adjoint fluxes from which MCNP weight windows and source bias parameters are generated. Investigative calculations were performed using a simple block model and a simplified full-scale model of the PWR containment, in which the adjoint source was placed in various regions. In general, it was shown that placement of the adjoint source on the periphery of the model provided adequate results for regions reasonably close to the source (e.g., within the containment structure for the reactor source). A modification to the CADIS/ADVANTG methodology was also studied in which a global adjoint source is weighted by the reciprocal of the dose response calculated by an earlier forward discrete ordinates calculation. This method showed improved results over those using the standard CADIS/ADVANTG approach, and its further investigation is recommended for future efforts.« less

A Toy Model of Electrodynamics in (1 + 1) Dimensions

ERIC Educational Resources Information Center

Boozer, A. D.

2007-01-01

A model is presented that describes a scalar field interacting with a point particle in (1+1) dimensions. The model exhibits many of the same phenomena that appear in classical electrodynamics, such as radiation and radiation damping, yet has a much simpler mathematical structure. By studying these phenomena in a highly simplified model, the…

Consumer Learning for University Students: A Case for a Curriculum

ERIC Educational Resources Information Center

Crafford, Sharon; Bitzer, Eli

2009-01-01

This article indicates how the application of a simplified version of the analytical abstraction method (AAM) was used in curriculum development for consumer learning at one higher education institution in South Africa. We used a case study design and qualitative research methodology to generate data through semi-structured interviews with eight…

14 CFR Appendix A to Part 23 - Simplified Design Load Criteria

Code of Federal Regulations, 2012 CFR

2012-01-01

... imposed when the particular items are installed in the airplane. The engine mount, however, must be.... (d) Supplementary conditions; rear lift truss; engine torque; side load on engine mount. Each of the... weight. (2) Each engine mount and its supporting structures must be designed for the maximum limit torque...

14 CFR Appendix A to Part 23 - Simplified Design Load Criteria

Code of Federal Regulations, 2014 CFR

2014-01-01

... imposed when the particular items are installed in the airplane. The engine mount, however, must be.... (d) Supplementary conditions; rear lift truss; engine torque; side load on engine mount. Each of the... weight. (2) Each engine mount and its supporting structures must be designed for the maximum limit torque...

14 CFR Appendix A to Part 23 - Simplified Design Load Criteria

Code of Federal Regulations, 2013 CFR

2013-01-01

... imposed when the particular items are installed in the airplane. The engine mount, however, must be.... (d) Supplementary conditions; rear lift truss; engine torque; side load on engine mount. Each of the... weight. (2) Each engine mount and its supporting structures must be designed for the maximum limit torque...

Myth Structure and Media Fiction Plot: An Exploration.

ERIC Educational Resources Information Center

Harless, James D.

Based on the general research of Joseph Campbell in adventure plots from mythology, the author explores the simplified monomyth plots currently in frequent use in mass media programing. The close relationship of media fiction to mythic stories is established through the analysis of more than 25 stories resulting from media broadcasting. The media…

Low-Hanging Fruit: How Boards Can Improve Education Now through Pedagogy, Portability, and Price

ERIC Educational Resources Information Center

Smith, Peter

2011-01-01

Boards do not have to wait for coming reforms to improve pricing and academic structure for students. They can have a significant impact immediately by making recognized learning portable, simplifying pricing, and reducing costs to students. Developmental education, blended and online learning, and adaptive learning are being touted as…

Trait covariance: the functional warp of plant diversity?

DOE PAGES

Walker, Anthony P.; McCormack, M. Luke; Messier, Julie; ...

2017-11-07

In 300 BC Ancient Greece, Theophrastus was one of the first to organize the diversity of plant life on Earth into categories of function and use (Theophrastus, 1916). Currently, scientists are still working to simplify the vast array of plant species and forms in order to distill general features of plant function, structure, and strategy.

Forest thinning changes movement patterns and habitat use by Pacific marten

Treesearch

Katie M. Moriarty; Clinton W. Epps; William J. Zielinski

2016-01-01

ABSTRACT Simplifying stand structure to reduce fuel density is a high priority for forest managers; however, affects to Pacific marten (Martes caurina) movement and connectivity are unknown. We evaluated whether thinning forests to reduce fuels influenced movements of Pacific marten. We collected movement paths from 22 martens using global positioning system telemetry...

Trait covariance: the functional warp of plant diversity?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Anthony P.; McCormack, M. Luke; Messier, Julie

In 300 BC Ancient Greece, Theophrastus was one of the first to organize the diversity of plant life on Earth into categories of function and use (Theophrastus, 1916). Currently, scientists are still working to simplify the vast array of plant species and forms in order to distill general features of plant function, structure, and strategy.

Simplified Analytical Model of a Covered Burr-Arch-Truss Timber Bridge

Treesearch

F. Fanous; D. Rammer; T. Wipf

2013-01-01

Due to the importance of historical timber covered bridges throughout history, their preservation is necessary. However, conducting an accurate structural evaluation of these types of bridges has always caused difficulties to bridge engineers. This paper summarizes an investigation that was sponsored by the Federal Highway Administration and the USDA Forest Products...

76 FR 65307 - Self-Regulatory Organizations; Financial Industry Regulatory Authority, Inc.; Notice of Filing of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-20

... Equity Security would fall into one of six tiers rather than nine tiers. Specifically, for OTC Equity... proposing changes to the minimum quotation sizes to, among other things, simplify the tier structure... quotations in this lower- priced tier should result in more substantive dollar-value commitments to the...

Nested Neural Networks

NASA Technical Reports Server (NTRS)

Baram, Yoram

1992-01-01

Report presents analysis of nested neural networks, consisting of interconnected subnetworks. Analysis based on simplified mathematical models more appropriate for artificial electronic neural networks, partly applicable to biological neural networks. Nested structure allows for retrieval of individual subpatterns. Requires fewer wires and connection devices than fully connected networks, and allows for local reconstruction of damaged subnetworks without rewiring entire network.

Rugged microelectronic module package supports circuitry on heat sink

NASA Technical Reports Server (NTRS)

Johnson, A. L.

1966-01-01

Rugged module package for thin film hybrid microcircuits incorporated a rigid, thermally conductive support structure, which serves as a heat sink, and a lead wire block in which T-shaped electrical connectors are potted. It protects the circuitry from shock and vibration loads, dissipates internal heat, and simplifies electrical connections between adjacent modules.

Optoelectronic Materials Center

DTIC Science & Technology

1991-06-11

surface - emitting GaAs/AIGaAs vertical - cavity laser (TJ- VCSEL ) incorporating wavelength-resonant...multi-quantum well, vertical cavity surface - emitted laser . This structure consists entirely of undoped epilayers, thus simplifying the problems of... cavity surface - emitting lasers ( VCSELs ) for doubling and for parallel optical data processing. Progress - GaAIAs/GaAs and InGaAs/GaAs RPG- VCSEL

Position uncertainty distribution for articulated arm coordinate measuring machine based on simplified definite integration

NASA Astrophysics Data System (ADS)

You, Xu; Zhi-jian, Zong; Qun, Gao

2018-07-01

This paper describes a methodology for the position uncertainty distribution of an articulated arm coordinate measuring machine (AACMM). First, a model of the structural parameter uncertainties was established by statistical method. Second, the position uncertainty space volume of the AACMM in a certain configuration was expressed using a simplified definite integration method based on the structural parameter uncertainties; it was then used to evaluate the position accuracy of the AACMM in a certain configuration. Third, the configurations of a certain working point were calculated by an inverse solution, and the position uncertainty distribution of a certain working point was determined; working point uncertainty can be evaluated by the weighting method. Lastly, the position uncertainty distribution in the workspace of the ACCMM was described by a map. A single-point contrast test of a 6-joint AACMM was carried out to verify the effectiveness of the proposed method, and it was shown that the method can describe the position uncertainty of the AACMM and it was used to guide the calibration of the AACMM and the choice of AACMM’s accuracy area.

Structure, function, and control of the human musculoskeletal network

PubMed Central

Murphy, Andrew C.; Muldoon, Sarah F.; Baker, David; Lastowka, Adam; Bennett, Brittany; Yang, Muzhi

2018-01-01

The human body is a complex organism, the gross mechanical properties of which are enabled by an interconnected musculoskeletal network controlled by the nervous system. The nature of musculoskeletal interconnection facilitates stability, voluntary movement, and robustness to injury. However, a fundamental understanding of this network and its control by neural systems has remained elusive. Here we address this gap in knowledge by utilizing medical databases and mathematical modeling to reveal the organizational structure, predicted function, and neural control of the musculoskeletal system. We constructed a highly simplified whole-body musculoskeletal network in which single muscles connect to multiple bones via both origin and insertion points. We demonstrated that, using this simplified model, a muscle’s role in this network could offer a theoretical prediction of the susceptibility of surrounding components to secondary injury. Finally, we illustrated that sets of muscles cluster into network communities that mimic the organization of control modules in primary motor cortex. This novel formalism for describing interactions between the muscular and skeletal systems serves as a foundation to develop and test therapeutic responses to injury, inspiring future advances in clinical treatments. PMID:29346370

Towards engineered branch placement: Unreal™ match between vapour-liquid-solid glancing angle deposition nanowire growth and simulation

NASA Astrophysics Data System (ADS)

Taschuk, M. T.; Tucker, R. T.; LaForge, J. M.; Beaudry, A. L.; Kupsta, M. R.; Brett, M. J.

2013-12-01

The vapour-liquid-solid glancing angle deposition (VLS-GLAD) process is capable of producing complex nanotree structures with control over azimuthal branch orientation and height. We have developed a thin film growth simulation including ballistic deposition, simplified surface diffusion, and droplet-mediated cubic crystal growth for the VLS-GLAD process using the UnrealTM Development Kit. The use of a commercial game engine has provided an interactive environment while allowing a custom physics implementation. Our simulation's output is verified against experimental data, including a volumetric film reconstruction produced using focused ion beam and scanning-electron microscopy (SEM), crystallographic texture, and morphological characteristics such as branch orientation. We achieve excellent morphological and texture agreement with experimental data, as well as qualitative agreement with SEM imagery. The simplified physics in our model reproduces the experimental films, indicating that the dominant role flux geometry plays in the VLS-GLAD competitive growth process responsible for azimuthally oriented branches and biaxial crystal texture evolution. The simulation's successful reproduction of experimental data indicates that it should have predictive power in designing novel VLS-GLAD structures.

Testing a simple control law to reduce broadband frequency harmonic vibrations using semi-active tuned mass dampers

NASA Astrophysics Data System (ADS)

Moutinho, Carlos

2015-05-01

This paper is focused on the control problems related to semi-active tuned mass dampers (TMDs) used to reduce harmonic vibrations, specially involving civil structures. A simplified version of the phase control law is derived and its effectiveness is investigated and evaluated. The objective is to improve the functioning of control systems of this type by simplifying the measurement process and reducing the number of variables involved, making the control system more feasible and reliable. Because the control law is of ON/OFF type, combined with appropriate trigger conditions, the activity of the actuation system may be significantly reduced, which may be of few seconds a day in many practical cases, increasing the durability of the device and reducing its maintenance. Moreover, due to the ability of the control system to command the motion of the inertial mass, the semi-active TMD is relatively insensitive to its initial tuning, resulting in the capability of self-tuning and in the possibility of controlling several vibration modes of a structure over a significant broadband frequency.

Aerodynamic drag control by pulsed jets on simplified car geometry

NASA Astrophysics Data System (ADS)

Gilliéron, Patrick; Kourta, Azeddine

2013-02-01

Aerodynamic drag control by pulsed jets is tested in a wind tunnel around a simplified car geometry named Ahmed body with a rear slant angle of 35°. Pulsed jet actuators are located 5 × 10-3 m from the top of the rear window. These actuators are produced by a pressure difference ranging from 1.5 to 6.5 × 105 Pa. Their excitation frequency can vary between 10 and 550 Hz. The analysis of the control effects is based on wall visualizations, aerodynamic drag coefficient measurements, and the velocity fields obtained by 2D PIV measurements. The maximum drag reduction is 20 % and is obtained for the excitation frequency F j = 500 Hz and for the pressure difference ∆ P = 1.5 × 105 Pa. This result is linked with a substantial reduction in the transverse development of the longitudinal vortex structures coming from the left and right lateral sides of the rear window, with a displacement of the vortex centers downstream and with a decrease in the transverse rotational absolute values of these structures.

Effects of network node consolidation in optical access and aggregation networks on costs and power consumption

NASA Astrophysics Data System (ADS)

Lange, Christoph; Hülsermann, Ralf; Kosiankowski, Dirk; Geilhardt, Frank; Gladisch, Andreas

2010-01-01

The increasing demand for higher bit rates in access networks requires fiber deployment closer to the subscriber resulting in fiber-to-the-home (FTTH) access networks. Besides higher access bit rates optical access network infrastructure and related technologies enable the network operator to establish larger service areas resulting in a simplified network structure with a lower number of network nodes. By changing the network structure network operators want to benefit from a changed network cost structure by decreasing in short and mid term the upfront investments for network equipment due to concentration effects as well as by reducing the energy costs due to a higher energy efficiency of large network sites housing a high amount of network equipment. In long term also savings in operational expenditures (OpEx) due to the closing of central office (CO) sites are expected. In this paper different architectures for optical access networks basing on state-of-the-art technology are analyzed with respect to network installation costs and power consumption in the context of access node consolidation. Network planning and dimensioning results are calculated for a realistic network scenario of Germany. All node consolidation scenarios are compared against a gigabit capable passive optical network (GPON) based FTTH access network operated from the conventional CO sites. The results show that a moderate reduction of the number of access nodes may be beneficial since in that case the capital expenditures (CapEx) do not rise extraordinarily and savings in OpEx related to the access nodes are expected. The total power consumption does not change significantly with decreasing number of access nodes but clustering effects enable a more energyefficient network operation and optimized power purchase order quantities leading to benefits in energy costs.

Thermal instability in gravitationally stratified plasmas: implications for multiphase structure in clusters and galaxy haloes

NASA Astrophysics Data System (ADS)

McCourt, Michael; Sharma, Prateek; Quataert, Eliot; Parrish, Ian J.

2012-02-01

We study the interplay among cooling, heating, conduction and magnetic fields in gravitationally stratified plasmas using simplified, plane-parallel numerical simulations. Since the physical heating mechanism remains uncertain in massive haloes such as groups or clusters, we adopt a simple, phenomenological prescription which enforces global thermal equilibrium and prevents a cooling flow. The plasma remains susceptible to local thermal instability, however, and cooling drives an inward flow of material. For physically plausible heating mechanisms in clusters, the thermal stability of the plasma is independent of its convective stability. We find that the ratio of the cooling time-scale to the dynamical time-scale tcool/tff controls the non-linear evolution and saturation of the thermal instability: when tcool/tff≲ 1, the plasma develops extended multiphase structure, whereas when tcool/tff≳ 1 it does not. (In a companion paper, we show that the criterion for thermal instability in a more realistic, spherical potential is somewhat less stringent, tcool/tff≲ 10.) When thermal conduction is anisotropic with respect to the magnetic field, the criterion for multiphase gas is essentially independent of the thermal conductivity of the plasma. Our criterion for local thermal instability to produce multiphase structure is an extension of the cold versus hot accretion modes in galaxy formation that applies at all radii in hot haloes, not just to the virial shock. We show that this criterion is consistent with data on multiphase gas in galaxy groups and clusters; in addition, when tcool/tff≳ 1, the net cooling rate to low temperatures and the mass flux to small radii are suppressed enough relative to models without heating to be qualitatively consistent with star formation rates and X-ray line emission in groups and clusters.

Development and validation of a simplified titration method for monitoring volatile fatty acids in anaerobic digestion.

PubMed

Sun, Hao; Guo, Jianbin; Wu, Shubiao; Liu, Fang; Dong, Renjie

2017-09-01

The volatile fatty acids (VFAs) concentration has been considered as one of the most sensitive process performance indicators in anaerobic digestion (AD) process. However, the accurate determination of VFAs concentration in AD processes normally requires advanced equipment and complex pretreatment procedures. A simplified method with fewer sample pretreatment procedures and improved accuracy is greatly needed, particularly for on-site application. This report outlines improvements to the Nordmann method, one of the most popular titrations used for VFA monitoring. The influence of ion and solid interfering subsystems in titrated samples on results accuracy was discussed. The total solid content in titrated samples was the main factor affecting accuracy in VFA monitoring. Moreover, a high linear correlation was established between the total solids contents and VFA measurement differences between the traditional Nordmann equation and gas chromatography (GC). Accordingly, a simplified titration method was developed and validated using a semi-continuous experiment of chicken manure anaerobic digestion with various organic loading rates. The good fitting of the results obtained by this method in comparison with GC results strongly supported the potential application of this method to VFA monitoring. Copyright © 2017. Published by Elsevier Ltd.

Probabilistic Structures Analysis Methods (PSAM) for select space propulsion system components

NASA Technical Reports Server (NTRS)

1991-01-01

The basic formulation for probabilistic finite element analysis is described and demonstrated on a few sample problems. This formulation is based on iterative perturbation that uses the factorized stiffness on the unperturbed system as the iteration preconditioner for obtaining the solution to the perturbed problem. This approach eliminates the need to compute, store and manipulate explicit partial derivatives of the element matrices and force vector, which not only reduces memory usage considerably, but also greatly simplifies the coding and validation tasks. All aspects for the proposed formulation were combined in a demonstration problem using a simplified model of a curved turbine blade discretized with 48 shell elements, and having random pressure and temperature fields with partial correlation, random uniform thickness, and random stiffness at the root.

New evidence favoring multilevel decomposition and optimization

NASA Technical Reports Server (NTRS)

Padula, Sharon L.; Polignone, Debra A.

1990-01-01

The issue of the utility of multilevel decomposition and optimization remains controversial. To date, only the structural optimization community has actively developed and promoted multilevel optimization techniques. However, even this community acknowledges that multilevel optimization is ideally suited for a rather limited set of problems. It is warned that decomposition typically requires eliminating local variables by using global variables and that this in turn causes ill-conditioning of the multilevel optimization by adding equality constraints. The purpose is to suggest a new multilevel optimization technique. This technique uses behavior variables, in addition to design variables and constraints, to decompose the problem. The new technique removes the need for equality constraints, simplifies the decomposition of the design problem, simplifies the programming task, and improves the convergence speed of multilevel optimization compared to conventional optimization.

Simplified Analysis of Airspike Heat Flux Into Lightcraft Thermal Management System

NASA Astrophysics Data System (ADS)

Head, Dean R.; Seo, Junghwa; Cassenti, Brice N.; Myrabo, Leik N.

2005-04-01

An approximate method is presented for estimating the airspike heat flux into a 9-meter diameter lightcraft, integrated over its flight to low Earth orbit. The super-pressure lightcraft's exotic twin-hull, sandwich structure is assumed to be fabricated from SiC/SiC thin-film ceramic matrix composites of semiconductor grade purity, giving superior structural properties while being transparent to 35-GHz microwave radiation. The vehicle's MHD slipstream accelerator engine is energized by an annular microwave power beam — converted on-board into DC electric power by two concentric, water-cooled microwave rectenna arrays. The vehicle's airspike is created by a central 3-m diameter laser beam that sustains a laser-supported detonation wave at a distance of 10-m ahead of the craft; the LSD wave propagates up the beam with a velocity that matches the lightcraft's flight speed. The simplified analysis, which is based on aerodynamic heating during re-entry, shows that helium flowing at a velocity of 10 m/s through the lightcraft's double-hull is sufficient to keep the outer, 0.13-mm thick SiC skin safely under its maximum service temperature. The interior helium pressurant that maintains the structural integrity of this exotic pressure-airship, increases in temperature by only 25 K during the flight to LEO.

Transfer of the left-side bias effect in perceptual expertise: The case of simplified and traditional Chinese character recognition

PubMed Central

Liu, Tianyin; Yeh, Su-Ling

2018-01-01

The left-side bias (LSB) effect observed in face and expert Chinese character perception is suggested to be an expertise marker for visual object recognition. However, in character perception this effect is limited to characters printed in a familiar font (font-sensitive LSB effect). Here we investigated whether the LSB and font-sensitive LSB effects depend on participants’ familiarity with global structure or local component information of the stimuli through examining their transfer effects across simplified and traditional Chinese scripts: the two Chinese scripts share similar overall structures but differ in the visual complexity of local components in general. We found that LSB in expert Chinese character processing could be transferred to the Chinese script that the readers are unfamiliar with. In contrast, the font-sensitive LSB effect did not transfer, and was limited to characters with the visual complexity the readers were most familiar with. These effects suggest that the LSB effect may be generalized to another visual category with similar overall structures; in contrast, effects of within-category variations such as fonts may depend on familiarity with local component information of the stimuli, and thus may be limited to the exemplars of the category that experts are typically exposed to. PMID:29608570

Decomposed fuzzy systems and their application in direct adaptive fuzzy control.

PubMed

Hsueh, Yao-Chu; Su, Shun-Feng; Chen, Ming-Chang

2014-10-01

In this paper, a novel fuzzy structure termed as the decomposed fuzzy system (DFS) is proposed to act as the fuzzy approximator for adaptive fuzzy control systems. The proposed structure is to decompose each fuzzy variable into layers of fuzzy systems, and each layer is to characterize one traditional fuzzy set. Similar to forming fuzzy rules in traditional fuzzy systems, layers from different variables form the so-called component fuzzy systems. DFS is proposed to provide more adjustable parameters to facilitate possible adaptation in fuzzy rules, but without introducing a learning burden. It is because those component fuzzy systems are independent so that it can facilitate minimum distribution learning effects among component fuzzy systems. It can be seen from our experiments that even when the rule number increases, the learning time in terms of cycles is still almost constant. It can also be found that the function approximation capability and learning efficiency of the DFS are much better than that of the traditional fuzzy systems when employed in adaptive fuzzy control systems. Besides, in order to further reduce the computational burden, a simplified DFS is proposed in this paper to satisfy possible real time constraints required in many applications. From our simulation results, it can be seen that the simplified DFS can perform fairly with a more concise decomposition structure.

Optimal mapping of terrestrial gamma dose rates using geological parent material and aerogeophysical survey data.

PubMed

Rawlins, B G; Scheib, C; Tyler, A N; Beamish, D

2012-12-01

Regulatory authorities need ways to estimate natural terrestrial gamma radiation dose rates (nGy h⁻¹) across the landscape accurately, to assess its potential deleterious health effects. The primary method for estimating outdoor dose rate is to use an in situ detector supported 1 m above the ground, but such measurements are costly and cannot capture the landscape-scale variation in dose rates which are associated with changes in soil and parent material mineralogy. We investigate the potential for improving estimates of terrestrial gamma dose rates across Northern Ireland (13,542 km²) using measurements from 168 sites and two sources of ancillary data: (i) a map based on a simplified classification of soil parent material, and (ii) dose estimates from a national-scale, airborne radiometric survey. We used the linear mixed modelling framework in which the two ancillary variables were included in separate models as fixed effects, plus a correlation structure which captures the spatially correlated variance component. We used a cross-validation procedure to determine the magnitude of the prediction errors for the different models. We removed a random subset of 10 terrestrial measurements and formed the model from the remainder (n = 158), and then used the model to predict values at the other 10 sites. We repeated this procedure 50 times. The measurements of terrestrial dose vary between 1 and 103 (nGy h⁻¹). The median absolute model prediction errors (nGy h⁻¹) for the three models declined in the following order: no ancillary data (10.8) > simple geological classification (8.3) > airborne radiometric dose (5.4) as a single fixed effect. Estimates of airborne radiometric gamma dose rate can significantly improve the spatial prediction of terrestrial dose rate.

Design of one-kilometer-long antenna sticks and support structure for a geosynchronous satellite

NASA Astrophysics Data System (ADS)

Freeman, Janet Elizabeth

This study develops a preliminary structural design for three one-kilometer-long antenna sticks and an antenna support structure for a geosynchronous earth-imaging satellite. On each of the antenna sticks is mounted a linear array of over 16,000 antenna elements. The antenna sticks are parallel to each other, and are spaced 1 km apart so that they form the corners of an imaginary triangular tube. This tube is spinning about its long axis. Antenna performance requires that the position of each antenna element be known to an accuracy of 0.5 cm, and that the spacecraft's spin axis be parallel to the earth's spin axis within one degree. Assuming that the position of each joint on each antenna stick is known, the antenna sticks are designed as beams under a uniformly distributed acceleration (due to spacecraft spin) to meet the displacement accuracy requirements for the antenna elements. Both a thin-walled round tube and a three-longeron double-laced truss are considered for the antenna stick structure. A spacecraft spinrate is chosen by considering the effects of environmental torques on the precession of a simplified spacecraft. A preliminary truss-like support structure configuration is chosen, and analyzed in quasi-static equilibrium with control thrusters firing to estimate the axial loads in the structural members. The compressive loads found by this analysis are used to design the support structure members to be buckling-critical three-longeron double-laced truss columns. Some tension-only members consisting of Kevlar cord are included in the design to eliminate the need for bulkier members. The lateral vibration modes of the individual structural members are found by conventional analysis -- the fundamental frequencies are as low as 0.0066 Hz. Finite element dynamic analyses of the structure in free vibration confirm that simplified models of the structure and members can be used to determine the structural modes and natural frequencies for design purposes.

Laminar Diffusion Flame Studies (Ground- and Space-Based Studies)

NASA Technical Reports Server (NTRS)

Dai, Z.; El-Leathy, A. M.; Lin, K.-C.; Sunderland, P. B.; Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2000-01-01

Laminar diffusion flames are of interest because they provide model flame systems that are far more tractable for analysis and experiments than more practical turbulent diffusion flames. Certainly, understanding flame processes within laminar diffusion flames must precede understanding these processes in more complex turbulent diffusion flames. In addition, many properties of laminar diffusion flames are directly relevant to turbulent diffusion flames using laminar flamelet concepts. Laminar jet diffusion flame shapes (luminous flame boundaries) have been of particular interest since the classical study of Burke and Schumann because they are a simple nonintrusive measurement that is convenient for evaluating flame structure predictions. Thus, consideration of laminar flame shapes is undertaken in the following, emphasizing conditions where effects of gravity are small, due to the importance of such conditions to practical applications. Another class of interesting properties of laminar diffusion flames are their laminar soot and smoke point properties (i.e., the flame length, fuel flow rate, characteristic residence time, etc., at the onset of soot appearance in the flame (the soot point) and the onset of soot emissions from the flame (the smoke point)). These are useful observable soot properties of nonpremixed flames because they provide a convenient means to rate several aspects of flame sooting properties: the relative propensity of various fuels to produce soot in flames; the relative effects of fuel structure, fuel dilution, flame temperature and ambient pressure on the soot appearance and emission properties of flames; the relative levels of continuum radiation from soot in flames; and effects of the intrusion of gravity (or buoyant motion) on emissions of soot from flames. An important motivation to define conditions for soot emissions is that observations of laminar jet diffusion flames in critical environments, e.g., space shuttle and space station facilities, cannot involve soot emitting flames in order to ensure that test chamber windows used for experimental observations are not blocked by soot deposits, thereby compromising unusually valuable experimental results. Another important motivation to define conditions where soot is present in diffusion flames is that flame chemistry, transport and radiation properties are vastly simplified when soot is absent, making such flames far more tractable for detailed numerical simulations than corresponding soot-containing flames. Motivated by these observations, the objectives of this phase of the investigation were as follows: (1) Observe flame-sheet shapes (the location of the reaction zone near phi=1) of nonluminous (soot free) laminar jet diffusion flames in both still and coflowing air and use these results to develop simplified models of flame-sheet shapes for these conditions; (2) Observe luminous flame boundaries of luminous (soot-containing) laminar jet diffusion flames in both still and coflowing air and use these results to develop simplified models of luminous flame boundaries for these conditions. In order to fix ideas here, maximum luminous flame boundaries at the laminar smoke point conditions were sought, i.e., luminous flame boundaries at the laminar smoke point; (3) Observe effects of coflow on laminar soot- and smoke-point conditions because coflow has been proposed as a means to control soot emissions and minimize the presence of soot in diffusion flames.

Design, synthesis and biological evaluation of paclitaxel-mimics possessing only the oxetane D-ring and side chain structures.

PubMed

Chen, Xing-Xiu; Gao, Feng; Wang, Qi; Huang, Xing; Wang, Dan

2014-01-01

Two spiro paclitaxel-mimics consisting only of an oxetane D-ring and a C-13 side chain were designed and synthesized on the basis of analysis of structure-activity relationships (SAR) of paclitaxel. In vitro microtubule-stabilizing and antiproliferative assays indicated a moderate weaker activity of the mimics than paclitaxel, but which still represented the first example of simplified paclitaxel analogues with significant anti-tumor biological activity. Copyright © 2013 Elsevier B.V. All rights reserved.

A topological hierarchy for functions on triangulated surfaces.

PubMed

Bremer, Peer-Timo; Edelsbrunner, Herbert; Hamann, Bernd; Pascucci, Valerio

2004-01-01

We combine topological and geometric methods to construct a multiresolution representation for a function over a two-dimensional domain. In a preprocessing stage, we create the Morse-Smale complex of the function and progressively simplify its topology by cancelling pairs of critical points. Based on a simple notion of dependency among these cancellations, we construct a hierarchical data structure supporting traversal and reconstruction operations similarly to traditional geometry-based representations. We use this data structure to extract topologically valid approximations that satisfy error bounds provided at runtime.

Human infants' learning of social structures: the case of dominance hierarchy.

PubMed

Mascaro, Olivier; Csibra, Gergely

2014-01-01

We tested 15-month-olds' capacity to represent social-dominance hierarchies with more than two agents. Our results showed that infants found it harder to memorize dominance relations that were presented in an order that hindered the incremental formation of a single structure (Study 1). These results suggest that infants attempt to build structures incrementally, relation by relation, thereby simplifying the complex problem of recognizing a social structure. Infants also found circular dominance structures harder to process than linear dominance structures (Study 2). These expectations about the shape of structures may facilitate learning. Our results suggest that infants attempt to represent social structures composed of social relations. They indicate that human infants go beyond learning about individual social partners and their respective relations and form hypotheses about how social groups are organized.

Assessment of nerve involvement in the lumbar spine: agreement between magnetic resonance imaging, physical examination and pain drawing findings.

PubMed

Bertilson, Bo C; Brosjö, Eva; Billing, Hans; Strender, Lars-Erik

2010-09-10

Detection of nerve involvement originating in the spine is a primary concern in the assessment of spine symptoms. Magnetic resonance imaging (MRI) has become the diagnostic method of choice for this detection. However, the agreement between MRI and other diagnostic methods for detecting nerve involvement has not been fully evaluated. The aim of this diagnostic study was to evaluate the agreement between nerve involvement visible in MRI and findings of nerve involvement detected in a structured physical examination and a simplified pain drawing. Sixty-one consecutive patients referred for MRI of the lumbar spine were - without knowledge of MRI findings - assessed for nerve involvement with a simplified pain drawing and a structured physical examination. Agreement between findings was calculated as overall agreement, the p value for McNemar's exact test, specificity, sensitivity, and positive and negative predictive values. MRI-visible nerve involvement was significantly less common than, and showed weak agreement with, physical examination and pain drawing findings of nerve involvement in corresponding body segments. In spine segment L4-5, where most findings of nerve involvement were detected, the mean sensitivity of MRI-visible nerve involvement to a positive neurological test in the physical examination ranged from 16-37%. The mean specificity of MRI-visible nerve involvement in the same segment ranged from 61-77%. Positive and negative predictive values of MRI-visible nerve involvement in segment L4-5 ranged from 22-78% and 28-56% respectively. In patients with long-standing nerve root symptoms referred for lumbar MRI, MRI-visible nerve involvement significantly underestimates the presence of nerve involvement detected by a physical examination and a pain drawing. A structured physical examination and a simplified pain drawing may reveal that many patients with "MRI-invisible" lumbar symptoms need treatment aimed at nerve involvement. Factors other than present MRI-visible nerve involvement may be responsible for findings of nerve involvement in the physical examination and the pain drawing.

Statistical genetics and evolution of quantitative traits

NASA Astrophysics Data System (ADS)

Neher, Richard A.; Shraiman, Boris I.

2011-10-01

The distribution and heritability of many traits depends on numerous loci in the genome. In general, the astronomical number of possible genotypes makes the system with large numbers of loci difficult to describe. Multilocus evolution, however, greatly simplifies in the limit of weak selection and frequent recombination. In this limit, populations rapidly reach quasilinkage equilibrium (QLE) in which the dynamics of the full genotype distribution, including correlations between alleles at different loci, can be parametrized by the allele frequencies. This review provides a simplified exposition of the concept and mathematics of QLE which is central to the statistical description of genotypes in sexual populations. Key results of quantitative genetics such as the generalized Fisher’s “fundamental theorem,” along with Wright’s adaptive landscape, are shown to emerge within QLE from the dynamics of the genotype distribution. This is followed by a discussion under what circumstances QLE is applicable, and what the breakdown of QLE implies for the population structure and the dynamics of selection. Understanding the fundamental aspects of multilocus evolution obtained through simplified models may be helpful in providing conceptual and computational tools to address the challenges arising in the studies of complex quantitative phenotypes of practical interest.

Biotransformation of trace organic chemicals during groundwater recharge: How useful are first-order rate constants?

PubMed

Regnery, J; Wing, A D; Alidina, M; Drewes, J E

2015-08-01

This study developed relationships between the attenuation of emerging trace organic chemicals (TOrC) during managed aquifer recharge (MAR) as a function of retention time, system characteristics, and operating conditions using controlled laboratory-scale soil column experiments simulating MAR. The results revealed that MAR performance in terms of TOrC attenuation is primarily determined by key environmental parameters (i.e., redox, primary substrate). Soil columns with suboxic and anoxic conditions performed poorly (i.e., less than 30% attenuation of moderately degradable TOrC) in comparison to oxic conditions (on average between 70-100% attenuation for the same compounds) within a residence time of three days. Given this dependency on redox conditions, it was investigated if key parameter-dependent rate constants are more suitable for contaminant transport modeling to properly capture the dynamic TOrC attenuation under field-scale conditions. Laboratory-derived first-order removal kinetics were determined for 19 TOrC under three different redox conditions and rate constants were applied to MAR field data. Our findings suggest that simplified first-order rate constants will most likely not provide any meaningful results if the target compounds exhibit redox dependent biotransformation behavior or if the intention is to exactly capture the decline in concentration over time and distance at field-scale MAR. However, if the intention is to calculate the percent removal after an extended time period and subsurface travel distance, simplified first-order rate constants seem to be sufficient to provide a first estimate on TOrC attenuation during MAR. Copyright © 2015 Elsevier B.V. All rights reserved.

Design Considerations for Thermally Insulating Structural Sandwich Panels for Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Blosser, Max L.

2016-01-01

Simplified thermal/structural sizing equations were derived for the in-plane loading of a thermally insulating structural sandwich panel. Equations were developed for the strain in the inner and outer face sheets of a sandwich subjected to uniaxial mechanical loads and differences in face sheet temperatures. Simple equations describing situations with no viable solution were developed. Key design parameters, material properties, and design principles are identified. A numerical example illustrates using the equations for a preliminary feasibility assessment of various material combinations and an initial sizing for minimum mass of a sandwich panel.

An approximate methods approach to probabilistic structural analysis

NASA Technical Reports Server (NTRS)

Mcclung, R. C.; Millwater, H. R.; Wu, Y.-T.; Thacker, B. H.; Burnside, O. H.

1989-01-01

A probabilistic structural analysis method (PSAM) is described which makes an approximate calculation of the structural response of a system, including the associated probabilistic distributions, with minimal computation time and cost, based on a simplified representation of the geometry, loads, and material. The method employs the fast probability integration (FPI) algorithm of Wu and Wirsching. Typical solution strategies are illustrated by formulations for a representative critical component chosen from the Space Shuttle Main Engine (SSME) as part of a major NASA-sponsored program on PSAM. Typical results are presented to demonstrate the role of the methodology in engineering design and analysis.

47 CFR 1.1409 - Commission consideration of the complaint.

Code of Federal Regulations, 2014 CFR

2014-10-01

... multiplying the percentage of the total usable space, or the percentage of the total duct or conduit capacity... paragraph 1.1409(e)(2)(ii) of this section: Rate = Space Factor × Cost Where Cost in Urbanized Service Areas... cable operators and telecommunications carriers: ER29JN01.014 simplified as: ER29JN01.015 If no inner...

47 CFR 1.1409 - Commission consideration of the complaint.

Code of Federal Regulations, 2013 CFR

2013-10-01

... multiplying the percentage of the total usable space, or the percentage of the total duct or conduit capacity... paragraph 1.1409(e)(2)(ii) of this section: Rate = Space Factor × Cost Where Cost in Urbanized Service Areas... cable operators and telecommunications carriers: ER29JN01.014 simplified as: ER29JN01.015 If no inner...

SPECIES AND ROTATION FREQUENCY INFLUENCE SOIL NITROGEN IN SIMPLIFIED TROPICAL PLANT COMMUNITIES

Treesearch

JOHN J. EWEL

2006-01-01

Among the many factors that potentially influence the rate at which nitrogen (N) becomes available to plants in terrestrial ecosystems are the identity and diversity of species composition, frequency of disturbance or stand turnover, and time. Replicated suites of investigator-designed communities afforded an opportunity to examine the effects of those factors on net N...

Sex Stereotyping Versus Perceived Value as the Mediator of Sex Differentiated Math Participation.

ERIC Educational Resources Information Center

Parsons, Jacquelynne Eccles

Students' stereotyping of mathematics as a male domain and their ratings of themselves on a simplified version of the PAQ was correlated with a battery of measures designed to assess student attitudes toward mathematics and their plans to continue taking mathematics courses. This was done to evaluate both sex-typed personality characteristics and…

Simplified Two-Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydorgen/Oxygen

NASA Technical Reports Server (NTRS)

Molnar, Melissa; Marek, C. John

2005-01-01

A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two-time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (> 1 x 10(exp -20) moles/cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T4). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/air fuel and for the H2/O2. A similar correlation is also developed using data from NASA s Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T4) as a function of overall fuel/air ratio, pressure and initial temperature (T3). High values of the regression coefficient R2 are obtained.

Summary of Simplified Two Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydrogen/Oxygen

NASA Technical Reports Server (NTRS)

Marek, C. John; Molnar, Melissa

2005-01-01

A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (greater than l x 10(exp -20)) moles per cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T(sub 4)). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/Air fuel and for H2/O2. A similar correlation is also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T(sub 4)) as a function of overall fuel/air ratio, pressure and initial temperature (T(sub 3)). High values of the regression coefficient R squared are obtained.

Quality rating and private-prices: Evidence from the nursing home industry.

PubMed

Huang, Sean Shenghsiu; Hirth, Richard A

2016-12-01

We use the rollout of the five-star rating of nursing homes to study how private-pay prices respond to quality rating. We find that star rating increases the price differential between top- and bottom-ranked facilities. On average, prices of top-ranked facilities increased by 4.8 to 6.0 percent more than the prices of bottom-ranked facilities. We find stronger price effects in markets that are less concentrated where consumers may have more choices of alternative nursing homes. Our results suggest that with simplified design and when markets are less concentrated, consumers are more responsive to quality reporting. Copyright © 2016 Elsevier B.V. All rights reserved.

A simplified analysis of the multigrid V-cycle as a fast elliptic solver

NASA Technical Reports Server (NTRS)

Decker, Naomi H.; Taasan, Shlomo

1988-01-01

For special model problems, Fourier analysis gives exact convergence rates for the two-grid multigrid cycle and, for more general problems, provides estimates of the two-grid convergence rates via local mode analysis. A method is presented for obtaining mutigrid convergence rate estimates for cycles involving more than two grids (using essentially the same analysis as for the two-grid cycle). For the simple cast of the V-cycle used as a fast Laplace solver on the unit square, the k-grid convergence rate bounds obtained by this method are sharper than the bounds predicted by the variational theory. Both theoretical justification and experimental evidence are presented.

Comparison of fundamental natural period of masonry and reinforced concrete buildings retrieved from experimental campaigns performed in Italy, Greece and Spain

NASA Astrophysics Data System (ADS)

Nigro, Antonella; Ponzo, Felice C.; Ditommaso, Rocco; Auletta, Gianluca; Iacovino, Chiara; Nigro, Domenico S.; Soupios, Pantelis; García-Fernández, Mariano; Jimenez, Maria-Jose

2017-04-01

Aim of this study is the experimental estimation of the dynamic characteristics of existing buildings and the comparison of the related fundamental natural period of the buildings (masonry and reinforced concrete) located in Basilicata (Italy), in Madrid (Spain) and in Crete (Greece). Several experimental campaigns, on different kind of structures all over the world, have been performed in the last years with the aim of proposing simplified relationships to evaluate the fundamental period of buildings. Most of formulas retrieved from experimental analyses provide vibration periods smaller than those suggested by the Italian Seismic Code (NTC2008) and the European Seismic Code (EC8). It is known that the fundamental period of a structure play a key role in the correct estimation of the spectral acceleration for seismic static analyses and to detect possible resonance phenomena with the foundation soil. Usually, simplified approaches dictate the use of safety factors greater than those related to in depth dynamic linear and nonlinear analyses with the aim to cover any unexpected uncertainties. The fundamental period calculated with the simplified formula given by both NTC 2008 and EC8 is higher than the fundamental period measured on the investigated structures in Italy, Spain and Greece. The consequence is that the spectral acceleration adopted in the seismic static analysis may be significantly different than real spectral acceleration. This approach could produces a decreasing in safety factors obtained using linear seismic static analyses. Based on numerical and experimental results, in order to confirm the results proposed in this work, authors suggest to increase the number of numerical and experimental tests considering also the effects of non-structural components and soil during small, medium and strong motion earthquakes. Acknowledgements This study was partially funded by the Italian Department of Civil Protection within the project DPC-RELUIS 2016 - RS4 ''Seismic observatory of structures and health monitoring'' and by the "Centre of Integrated Geomorphology for the Mediterranean Area - CGIAM" within the Framework Agreement with the University of Basilicata "Study, Research and Experimentation in the Field of Analysis and Monitoring of Seismic Vulnerability of Strategic and Relevant Buildings for the purposes of Civil Protection and Development of Innovative Strategies of Seismic Reinforcement".

Evaluation of rate law approximations in bottom-up kinetic models of metabolism.

PubMed

Du, Bin; Zielinski, Daniel C; Kavvas, Erol S; Dräger, Andreas; Tan, Justin; Zhang, Zhen; Ruggiero, Kayla E; Arzumanyan, Garri A; Palsson, Bernhard O

2016-06-06

The mechanistic description of enzyme kinetics in a dynamic model of metabolism requires specifying the numerical values of a large number of kinetic parameters. The parameterization challenge is often addressed through the use of simplifying approximations to form reaction rate laws with reduced numbers of parameters. Whether such simplified models can reproduce dynamic characteristics of the full system is an important question. In this work, we compared the local transient response properties of dynamic models constructed using rate laws with varying levels of approximation. These approximate rate laws were: 1) a Michaelis-Menten rate law with measured enzyme parameters, 2) a Michaelis-Menten rate law with approximated parameters, using the convenience kinetics convention, 3) a thermodynamic rate law resulting from a metabolite saturation assumption, and 4) a pure chemical reaction mass action rate law that removes the role of the enzyme from the reaction kinetics. We utilized in vivo data for the human red blood cell to compare the effect of rate law choices against the backdrop of physiological flux and concentration differences. We found that the Michaelis-Menten rate law with measured enzyme parameters yields an excellent approximation of the full system dynamics, while other assumptions cause greater discrepancies in system dynamic behavior. However, iteratively replacing mechanistic rate laws with approximations resulted in a model that retains a high correlation with the true model behavior. Investigating this consistency, we determined that the order of magnitude differences among fluxes and concentrations in the network were greatly influential on the network dynamics. We further identified reaction features such as thermodynamic reversibility, high substrate concentration, and lack of allosteric regulation, which make certain reactions more suitable for rate law approximations. Overall, our work generally supports the use of approximate rate laws when building large scale kinetic models, due to the key role that physiologically meaningful flux and concentration ranges play in determining network dynamics. However, we also showed that detailed mechanistic models show a clear benefit in prediction accuracy when data is available. The work here should help to provide guidance to future kinetic modeling efforts on the choice of rate law and parameterization approaches.

Structural, morphological, gas sensing and photocatalytic characterization of MoO3 and WO3 thin films prepared by the thermal vacuum evaporation technique

NASA Astrophysics Data System (ADS)

Arfaoui, A.; Touihri, S.; Mhamdi, A.; Labidi, A.; Manoubi, T.

2015-12-01

Thin films of molybdenum trioxide and tungsten trioxide were deposited on glass substrates using a simplified thermal evaporation under vacuum method monitored by heat treatment in flowing oxygen at 500 °C for 1 h. The structural and morphological properties of the films were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy. The X-ray diffraction analysis shows that the films of MoO3 and WO3 were well crystallized in orthorhombic and monoclinic phase respectively with the crystallites preferentially oriented toward (2 0 0) direction parallel a-axis for both samples. In literature, we have shown in previous papers that structural and surface morphology of metal thin films play an important role in the gas detection mechanism. In this article, we have studied the response evolution of MoO3 and WO3 thin films sensors ethanol versus time, working temperature and the concentration of the ethanol. It was found that these films had high sensitivity to ethanol, which made them as a good candidate for the ethanol sensor. Finally, the photocatalytic activity of the samples was evaluated with respect to the degradation reaction of a wastewater containing methylene blue (MB) under UV-visible light irradiation. The molybdenum trioxide exhibits a higher degradation rate than the tungsten trioxide thin films under similar experimental conditions.

Simplified tools for evaluating domestic ventilation systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maansson, L.G.; Orme, M.

1999-07-01

Within an International Energy Agency (IEA) project, Annex 27, experts from 8 countries (Canada, France, Italy, Japan, The Netherlands, Sweden, UK and USA) have developed simplified tools for evaluating domestic ventilation systems during the heating season. Tools for building and user aspects, thermal comfort, noise, energy, life cycle cost, reliability and indoor air quality (IAQ) have been devised. The results can be used both for dwellings at the design stage and after construction. The tools lead to immediate answers and indications about the consequences of different choices that may arise during discussion with clients. This paper presents an introduction tomore » these tools. Examples applications of the indoor air quality and energy simplified tools are also provided. The IAQ tool accounts for constant emission sources, CO{sub 2}, cooking products, tobacco smoke, condensation risks, humidity levels (i.e., for judging the risk for mould and house dust mites), and pressure difference (for identifying the risk for radon or land fill spillage entering the dwelling or problems with indoor combustion appliances). An elaborated set of design parameters were worked out that resulted in about 17,000 combinations. By using multi-variate analysis it was possible to reduce this to 174 combinations for IAQ. In addition, a sensitivity analysis was made using 990 combinations. The results from all the runs were used to develop a simplified tool, as well as quantifying equations relying on the design parameters. A computerized energy tool has also been developed within this project, which takes into account air tightness, climate, window airing pattern, outdoor air flow rate and heat exchange efficiency.« less

A randomized controlled trial of the different impression methods for the complete denture fabrication: Patient reported outcomes.

PubMed

Jo, Ayami; Kanazawa, Manabu; Sato, Yusuke; Iwaki, Maiko; Akiba, Norihisa; Minakuchi, Shunsuke

2015-08-01

To compare the effect of conventional complete dentures (CD) fabricated using two different impression methods on patient-reported outcomes in a randomized controlled trial (RCT). A cross-over RCT was performed with edentulous patients, required maxillomandibular CDs. Mandibular CDs were fabricated using two different methods. The conventional method used a custom tray border moulded with impression compound and a silicone. The simplified used a stock tray and an alginate. Participants were randomly divided into two groups. The C-S group had the conventional method used first, followed by the simplified. The S-C group was in the reverse order. Adjustment was performed four times. A wash out period was set for 1 month. The primary outcome was general patient satisfaction, measured using visual analogue scales, and the secondary outcome was oral health-related quality of life, measured using the Japanese version of the Oral Health Impact Profile for edentulous (OHIP-EDENT-J) questionnaire scores. Twenty-four participants completed the trial. With regard to general patient satisfaction, the conventional method was significantly more acceptable than the simplified. No significant differences were observed between the two methods in the OHIP-EDENT-J scores. This study showed CDs fabricated with a conventional method were significantly more highly rated for general patient satisfaction than a simplified. CDs, fabricated with the conventional method that included a preliminary impression made using alginate in a stock tray and subsequently a final impression made using silicone in a border moulded custom tray resulted in higher general patient satisfaction. UMIN000009875. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cooling rates for glass containing lunar compositions

NASA Technical Reports Server (NTRS)

Fang, C. Y.; Yinnon, H.; Uhlmann, D. R.

1983-01-01

Cooling rates required to form glassy or partly-crystalline bodies of 14 lunar compositions have been estimated using a previously introduced, simplified model. The calculated cooling rates are found to be in good agreement with cooling rates measured for the same compositions. Measurements are also reported of the liquidus temperature and glass transition temperature for each composition. Inferred cooling rates are combined with heat flow analyses to obtain insight into the thermal histories of samples 15422, 14162, 15025, 74220, 74241, 10084, 15425, and 15427. The critical cooling rates required to form glasses of 24 lunar compositions, including the 14 compositions of the present study, are suggested to increase systematically with increasing ratio of total network modifiers/total network formers in the compositions. This reflects the importance of melt viscosity in affecting glass formation.

Investigation of Particle Deposition in Internal Cooling Cavities of a Nozzle Guide Vane

NASA Astrophysics Data System (ADS)

Casaday, Brian Patrick

Experimental and computational studies were conducted regarding particle deposition in the internal film cooling cavities of nozzle guide vanes. An experimental facility was fabricated to simulate particle deposition on an impingement liner and upstream surface of a nozzle guide vane wall. The facility supplied particle-laden flow at temperatures up to 1000°F (540°C) to a simplified impingement cooling test section. The heated flow passed through a perforated impingement plate and impacted on a heated flat wall. The particle-laden impingement jets resulted in the buildup of deposit cones associated with individual impingement jets. The deposit growth rate increased with increasing temperature and decreasing impinging velocities. For some low flow rates or high flow temperatures, the deposit cones heights spanned the entire gap between the impingement plate and wall, and grew through the impingement holes. For high flow rates, deposit structures were removed by shear forces from the flow. At low temperatures, deposit formed not only as individual cones, but as ridges located at the mid-planes between impinging jets. A computational model was developed to predict the deposit buildup seen in the experiments. The test section geometry and fluid flow from the experiment were replicated computationally and an Eulerian-Lagrangian particle tracking technique was employed. Several particle sticking models were employed and tested for adequacy. Sticking models that accurately predicted locations and rates in external deposition experiments failed to predict certain structures or rates seen in internal applications. A geometry adaptation technique was employed and the effect on deposition prediction was discussed. A new computational sticking model was developed that predicts deposition rates based on the local wall shear. The growth patterns were compared to experiments under different operating conditions. Of all the sticking models employed, the model based on wall shear, in conjunction with geometry adaptation, proved to be the most accurate in predicting the forms of deposit growth. It was the only model that predicted the changing deposition trends based on flow temperature or Reynolds number, and is recommended for further investigation and application in the modeling of deposition in internal cooling cavities.

Multiple mechanisms generate a universal scaling with dissipation for the air-water gas transfer velocity

NASA Astrophysics Data System (ADS)

Katul, Gabriel; Liu, Heping

2017-02-01

A large corpus of field and laboratory experiments support the finding that the water side transfer velocity kL of sparingly soluble gases near air-water interfaces scales as kL˜(νɛ)1/4, where ν is the kinematic water viscosity and ɛ is the mean turbulent kinetic energy dissipation rate. Originally predicted from surface renewal theory, this scaling appears to hold for marine and coastal systems and across many environmental conditions. It is shown that multiple approaches to representing the effects of turbulence on kL lead to this expression when the Kolmogorov microscale is assumed to be the most efficient transporting eddy near the interface. The approaches considered range from simplified surface renewal schemes with distinct models for renewal durations, scaling and dimensional considerations, and a new structure function approach derived using analogies between scalar and momentum transfer. The work offers a new perspective as to why the aforementioned 1/4 scaling is robust.

Continuous assessment of volunteers' satisfaction in clinical research through simplified questionnaires.

PubMed

Pluchart, Hélène; Gaget, Olivier; Cracowski, Claire; Paris, Adeline; Cracowski, Jean-Luc

2018-01-06

In our clinical research center, a 27 multiple-choice and 3 verbatim questions satisfaction questionnaire has been used since 2008 in order to assess the satisfaction of the volunteers participating in our studies. In this work, we aimed at reducing the number of questions of this cumbersome questionnaire while exploring the same dimensions. We used k-mean and hierarchical clustering to determine which questions provided the same information or, on the contrary, which questions were able to discriminate a satisfied volunteer from an unsatisfied volunteer. We were able to reduce our satisfaction questionnaire from 30 questions to 6 closed-ended and 2 open-ended questions, which will allow to save volunteers time while increasing their participation rate. This questionnaire could be used in other structures practicing clinical research, as part of their quality process. Copyright © 2018 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

Upscaling transport of a reacting solute through a peridocially converging-diverging channel at pre-asymptotic times

NASA Astrophysics Data System (ADS)

Sund, Nicole L.; Bolster, Diogo; Dawson, Clint

2015-11-01

In this study we extend the Spatial Markov model, which has been successfully used to upscale conservative transport across a diverse range of porous media flows, to test if it can accurately upscale reactive transport, defined by a spatially heterogeneous first order degradation rate. We test the model in a well known highly simplified geometry, commonly considered as an idealized pore or fracture structure, a periodic channel with wavy boundaries. The edges of the flow domain have a layer through which there is no flow, but in which diffusion of a solute still occurs. Reactions are confined to this region. We demonstrate that the Spatial Markov model, an upscaled random walk model that enforces correlation between successive jumps, can reproduce breakthrough curves measured from microscale simulations that explicitly resolve all pertinent processes. We also demonstrate that a similar random walk model that does not enforce successive correlations is unable to reproduce all features of the measured breakthrough curves.

PIV Analysis Comparing Aerodynamic Downforce Devices on Race Car in Water Tunnel

NASA Astrophysics Data System (ADS)

Hellman, Sam; Tkacik, Peter; Uddin, Mesbah; Kelly, Scott

2010-11-01

There have been claims that the rear wing on the NASCAR Car of Tomorrow (COT) race car causes lift in the condition where the car spins during a crash and is traveling backwards down the track at a high rate of speed. When enough lift is generated, the race car can lose control and even fly off of the track surface completely. To address this concern, a new rear spoiler was designed by NASCAR to replace the wing and prevent this dangerous condition. Flow characteristics of both the rear wing and the new spoiler are qualitatively analyzed using particle image velocimetry (PIV). The experiment is done in a continuous flow water tunnel using a simplified 10% scale model COT. Flow structures are identified and compared for both the wing and spoiler. The same conditions are also reviewed when the car is traveling backwards as it might during a crash. The cause of the lift generated by the rear wing when in reverse is shown.

Oxygen reduction on a Pt(111) catalyst in HT-PEM fuel cells by density functional theory

NASA Astrophysics Data System (ADS)

Sun, Hong; Li, Jie; Almheiri, Saif; Xiao, Jianyu

2017-08-01

The oxygen reduction reaction plays an important role in the performance of high-temperature proton exchange membrane (HT-PEM) fuel cells. In this study, a molecular dynamics model, which is based on the density functional theory and couples the system's energy, the exchange-correlation energy functional, the charge density distribution function, and the simplified Kohn-Sham equation, was developed to simulate the oxygen reduction reaction on a Pt(111) surface. Additionally, an electrochemical reaction system on the basis of a four-electron reaction mechanism was also developed for this simulation. The reaction path of the oxygen reduction reaction, the product structure of each reaction step and the system's energy were simulated. It is found that the first step reaction of the first hydrogen ion with the oxygen molecule is the controlling step of the overall reaction. Increasing the operating temperature speeds up the first step reaction rate and slightly decreases its reaction energy barrier. Our results provide insight into the working principles of HT-PEM fuel cells.

Kinetic Monte Carlo simulations of ion-induced ripple formation: Dependence on flux, temperature, and defect concentration in the linear regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chason, E.; Chan, W. L.; Bharathi, M. S.

Low-energy ion bombardment produces spontaneous periodic structures (sputter ripples) on many surfaces. Continuum theories describe the pattern formation in terms of ion-surface interactions and surface relaxation kinetics, but many features of these models (such as defect concentration) are unknown or difficult to determine. In this work, we present results of kinetic Monte Carlo simulations that model surface evolution using discrete atomistic versions of the physical processes included in the continuum theories. From simulations over a range of parameters, we obtain the dependence of the ripple growth rate, wavelength, and velocity on the ion flux and temperature. The results are discussedmore » in terms of the thermally dependent concentration and diffusivity of ion-induced surface defects. We find that in the early stages of ripple formation the simulation results are surprisingly well described by the predictions of the continuum theory, in spite of simplifying approximations used in the continuum model.« less

Simulation study of a new inverse-pinch high Coulomb transfer switch

NASA Technical Reports Server (NTRS)

Choi, S. H.

1984-01-01

A simulation study of a simplified model of a high coulomb transfer switch is performed. The switch operates in an inverse pinch geometry formed by an all metal chamber, which greatly reduces hot spot formations on the electrode surfaces. Advantages of the switch over the conventional switches are longer useful life, higher current capability and lower inductance, which improves the characteristics required for a high repetition rate switch. The simulation determines the design parameters by analytical computations and comparison with the experimentally measured risetime, current handling capability, electrode damage, and hold-off voltages. The parameters of initial switch design can be determined for the anticipated switch performance. Results are in agreement with the experiment results. Although the model is simplified, the switch characteristics such as risetime, current handling capability, electrode damages, and hold-off voltages are accurately determined.

Radical nature of C- lignin

Treesearch

Laura Berstis; Thomas Elder; Michael Crowley; Gregg T. Beckham

2016-01-01

The recently discovered lignin composed of caffeoyl alcohol monolignols or C-lignin is particularly intriguing given its homogeneous, linear polymeric structure and exclusive benzodioxane linkage between monomers. By virtue of this simplified chemistry, the potential emerges for improved valorization strategies with C-lignin relative to other natural heterogeneous...

Using passive seismology to study the sub-surface and internal structure of Didymoon

NASA Astrophysics Data System (ADS)

Murdoch, N.; Hempel, S.; Pou, L.; Cadu, A.; Garcia, R. F.; Mimoun, D.; Margerin, L.; Karatekin, O.

2017-09-01

As there is evidence to suggest that asteroids are seismically active, passive rather than active seismology could be performed thus simplifying the mission design. Here we discuss the possibility of performing a passive seismic experiment on Didymoon; the secondary component of asteroid (65803) Didymos and the target of the joint ESA-NASA mission AIDA

Kinesthetic Life Cycle of Stars

NASA Astrophysics Data System (ADS)

Reinfeld, Erika L.; Hartman, Mark A.

We present a kinesthetic approach to learning about the life cycle of stars. Using a simplified two-layer model for stellar structure, learners recreate kinesthetically the birth, life, and death of low- and high-mass stars. Examples of how this activity has been used in several settings outside school time provide additional resources for extending student learning about this topic.

Forest processes from stands to landscapes: exploring model forecast uncertainties using cross-scale model comparison

Treesearch

Michael J. Papaik; Andrew Fall; Brian Sturtevant; Daniel Kneeshaw; Christian Messier; Marie-Josee Fortin; Neal Simon

2010-01-01

Forest management practices conducted primarily at the stand scale result in simplified forests with regeneration problems and low structural and biological diversity. Landscape models have been used to help design management strategies to address these problems. However, there remains a great deal of uncertainty that the actual management practices result in the...

Sex and the single squirrel: a genetic view of forest management in the Pacific Northwest.

Treesearch

Sally Duncan

2003-01-01

Forest management throughout the world is producing simplified forests. There is growing concern that these forests maintain neither complete vertebrate communities nor conditions favorable to maintenance of genetic diversity of those vertebrate populations that do find habitat in simply structured stands. Genetics is increasingly being used as a basis for management...

Changes in fish assemblage structure in the main-stem Willamette River, Oregon

EPA Science Inventory

The Willamette River if Oregon’s largest river, with a basin area of 29,800 km² and a mean annual discharge of 680 m³/3. Beginning in the 1890s, the channel was greatly simplified for navigation. By the 1940s, it was polluted by organic wastes, which resulted in low dissolved o...

Initial riparian down wood dynamics in relation to thinning and buffer width

Treesearch

Paul D. Anderson; Deanna H. Olson; Adrian Ares

2013-01-01

Down wood plays many functional roles in aquatic and riparian ecosystems. Simplifi cation of forest structure and low abundance of down wood in stream channels and riparian areas is a common legacy of historical management in headwater forests west of the Cascade Range in the US northwest. Contemporary management practices emphasize the implementation of vegetation...

Development of a simplified flexible pavement design protocol for New York State Department of Transportation based on the AASHTO mechanistic-empirical pavement design guide : final report.

DOT National Transportation Integrated Search

2017-01-01

The New York State Department of Transportation (NYSDOT) has used the AASHTO 1993 Design Guide for the design of new flexible pavement structures for more than two decades. The AASHTO 1993 Guide is based on the empirical design equations developed fr...

Development of a simplified flexible pavement design protocol for New York State Department of Transportation based on the AASHTO Mechanistic-Empirical Pavement Design Guide : technical summary.

DOT National Transportation Integrated Search

2017-01-01

This report summarizes the local calibration of the distress models for the Northeast (NE) region of the United States and the development of new design tables for new flexible pavement structures. Design, performance, and traffic data collected on t...

Wildland fire in ecosystems: effects of fire on fauna

Treesearch

Jane Kapler Smith

2000-01-01

VOLUME 1: Fires affect animals mainly through effects on their habitat. Fires often cause short-term increases in wildlife foods that contribute to increases in populations of some animals. These increases are moderated by the animals' ability to thrive in the altered, often simplified, structure of the postfire environment. The extent of fire effects on animal...

Single element laser beam shaper

DOEpatents

Zhang, Shukui [Yorktown, VA; Shinn, Michelle D [Newport News, VA

2005-09-13

A single lens laser beam shaper for converting laser beams from any spatial profile to a flat-top or uniform spatial profile. The laser beam shaper includes a lens having two aspheric surfaces. The beam shaper significantly simplifies the overall structure in comparison with conventional 2-element systems and therefore provides great ease in alignment and reduction of cost.

Between Curriculum Complexity and Stereotypes: Exploring Stereotypes of Teachers and Education in Media as a Question of Structural Violence

ERIC Educational Resources Information Center

Edling, Silvia

2015-01-01

The paper highlights four tendencies in the media reporting of teachers and education: (a) recurring patterns of defining education in crisis, (b) mantling responsibility as exterior spokespersons for education and teachers, (c) excluding teachers' and educational researchers' knowledge and experiences in the media and (d) simplifying the notion…

A Computer Simulation Comparing the Incentive Structures of Dictatorships and Democracies

ERIC Educational Resources Information Center

Nishikawa, Katsuo A.; Jaeger, Joseph

2011-01-01

The draw of simulations is that by replicating a simplified version of reality they can illustrate the repercussions that individual choices create. Students can play the role of a judge, an ambassador, or a parliamentarian and can experience first hand how their decisions play out. As a discipline, we assume that such practices are an improvement…

A Skeleton Tells Its Own Story: Forensic Analyses of Skeletal Elements for the Science Classroom Laboratory

ERIC Educational Resources Information Center

Naples, Virginia L.; Breed, David; Miller, Jon S.

2010-01-01

The techniques of forensic anthropology and pathology can provide new information to increase student interest in studying the structural details of the human skeleton. We present a simplified methodology for assessing skeletal ethnicity, sex, age, and stature. An inexpensive method has been devised for constructing an osteometric board to allow…

Eccentric superconducting RF cavity separator structure

DOEpatents

Aggus, John R.; Giordano, Salvatore T.; Halama, Henry J.

1976-01-01

Accelerator apparatus having an eccentric-shaped, iris-loaded deflecting cavity for an rf separator for a high energy high momentum, charged particle accelerator beam. In one embodiment, the deflector is superconducting, and the apparatus of this invention provides simplified machining and electron beam welding techniques. Model tests have shown that the electrical characteristics provide the desired mode splitting without adverse effects.

Alternative Approaches to the Family Life Cycle in the Analysis of Housing Consumption.

ERIC Educational Resources Information Center

McLeod, P. B.; Ellis, J. R.

1983-01-01

Used loan-approval data to analyze the effects of life-cycle stage on housing consumption. The detailed typologies were not generally superior to the more simplified approaches, except for per capita consumption. For per capita consumption, price, and quality, clear evidence is found for structural nonhomogeneity across life-cycle stages. (JAC)

The School of the Future. Stelco Trend. Number 34 in a Series.

ERIC Educational Resources Information Center

Walker, Howard V.; Arthur, E. R.

Floor plans and illustrations present a simplified building system for an elementary school that can be utilized by any school board. All components for the system can be drawn from existing products and readily integrated with the structure. The component assembly and connections are illustrated in detail. Factory production is utilized to reduce…

Mapping Practices of Christian Education: Toward a Framework of Contextual Differences around the Globe

ERIC Educational Resources Information Center

de Muynck, Bram; Reijnoudt-Klein, Willemieke; Spruyt-de Kloe, Marike

2017-01-01

This article reports the development of a framework that structures differences in Christian educational practices worldwide. One of its purposes is to simplify the complexity of the contexts in which global partners cooperate. The framework also offers the theoretical basis for an instrument that nongovernmental organizations can use to determine…

Weighing up the weighted case mix tool (WCMT): a psychometric investigation using confirmatory factor analysis.

PubMed

Duane, B G; Humphris, G; Richards, D; Okeefe, E J; Gordon, K; Freeman, R

2014-12-01

To assess the use of the WCMT in two Scottish health boards and to consider the impact of simplifying the tool to improve efficient use. A retrospective analysis of routine WCMT data (47,276 cases). Public Dental Service (PDS) within NHS Lothian and Highland. The WCMT consists of six criteria. Each criterion is measured independently on a four-point scale to assess patient complexity and the dental care for the disabled/impaired patient. Psychometric analyses on the data-set were conducted. Conventional internal consistency coefficients were calculated. Latent variable modelling was performed to assess the 'fit' of the raw data to a pre-specified measurement model. A Confirmatory Factor Analysis (CFA) was used to test three potential changes to the existing WCMT that included, the removal of the oral risk factor question, the removal of original weightings for scoring the Tool, and collapsing the 4-point rating scale to three categories. The removal of the oral risk factor question had little impact on the reliability of the proposed simplified CMT to discriminate between levels of patient complexity. The removal of weighting and collapsing each item's rating scale to three categories had limited impact on reliability of the revised tool. The CFA analysis provided strong evidence that a new, proposed simplified Case Mix Tool (sCMT) would operate closely to the pre-specified measurement model (the WMCT). A modified sCMT can demonstrate, without reducing reliability, a useful measure of the complexity of patient care. The proposed sCMT may be implemented within primary care dentistry to record patient complexity as part of an oral health assessment.

Risk stratification in middle-aged patients with congestive heart failure: prospective comparison of the Heart Failure Survival Score (HFSS) and a simplified two-variable model.

PubMed

Zugck, C; Krüger, C; Kell, R; Körber, S; Schellberg, D; Kübler, W; Haass, M

2001-10-01

The performance of a US-American scoring system (Heart Failure Survival Score, HFSS) was prospectively evaluated in a sample of ambulatory patients with congestive heart failure (CHF). Additionally, it was investigated whether the HFSS might be simplified by assessment of the distance ambulated during a 6-min walk test (6'WT) instead of determination of peak oxygen uptake (peak VO(2)). In 208 middle-aged CHF patients (age 54+/-10 years, 82% male, NYHA class 2.3+/-0.7; follow-up 28+/-14 months) the seven variables of the HFSS: CHF aetiology; heart rate; mean arterial pressure; serum sodium concentration; intraventricular conduction time; left ventricular ejection fraction (LVEF); and peak VO(2), were determined. Additionally, a 6'WT was performed. The HFSS allowed discrimination between patients at low, medium and high risk, with mortality rates of 16, 39 and 50%, respectively. However, the prognostic power of the HFSS was not superior to a two-variable model consisting only of LVEF and peak VO(2). The areas under the receiver operating curves (AUC) for prediction of 1-year survival were even higher for the two-variable model (0.84 vs. 0.74, P<0.05). Replacing peak VO(2) with 6'WT resulted in a similar AUC (0.83). The HFSS continued to predict survival when applied to this patient sample. However, the HFSS was inferior to a two-variable model containing only LVEF and either peak VO(2) or 6'WT. As the 6'WT requires no sophisticated equipment, a simplified two-variable model containing only LVEF and 6'WT may be more widely applicable, and is therefore recommended.

History of the Development of Liquid-Applied Coatings for Protection of Reinforced Concrete

NASA Technical Reports Server (NTRS)

Curran, Joseph J.; Hansen, marlin H.

2005-01-01

Corrosion of reinforcing steel in concrete is an insidious problem for structures at Kennedy Space Center (KSC). KSC is located on the coast of Florida in a highly corrosive atmosphere. Launch pads, highway bridge infrastructure, and buildings are strongly affected. To mitigate these problems, NASA initiated a development program for a Galvanic Liquid-Applied Coating System (GLACS). A breakthrough in this area would have great commercial value in transportation, marine and construction industry infrastructures. The patented NASA GLACS system has undergone considerable testing to meet the needs of commercialization. A moisture-cure coating gives excellent adhesion with ease of application compared to existing galvanic products on the market. The latest development, GalvaCori; can be sprayed or hand applied to almost any structure shape. A self-adhesive conductive tape system has been devised to simplify current collection within the coating areas. In testing programs, millivolt potential and milliamp output per square foot of anode have been closely studied at actual test sites. These two parameters are probably the most challenging items of a resin-based, room-temperature-applied, galvanic coating. Extensive re-formulation has resulted in a system that provides the needed polarization for catholic protection of reinforcing steel in concrete in a variety of structure environments. The rate of corrosion of rebar in concrete is greatly affected by the environment of the structure. In addition to this, for any given concrete structure; moisture level, carbonization, and chloride contamination influences the rate of rebar corrosion. Similarly, the cathodic protection level of galvanic systems is also dependent on the moisture level of the concrete. GalvaCorr is formulated to maintain galvanic activity as the moisture level of the structure declines. GalvaCorr is available as a three-part kit. The mixing step requires about ten minutes. The viscosity can be easily adjusted to meet the application needs. The pot or working life is four to six hours, depending on the temperature. GalvaCorr can be thought of as a spray-on coating, battery ready to provide up to -1.4 volts (relative to CSE) of cathodic protection (CP) potential.

Plasmonic detection of possible defects in multilayer nanohole array consisting of essential materials in simplified STT-RAM cell

NASA Astrophysics Data System (ADS)

Sadri-Moshkenani, Parinaz; Khan, Mohammad Wahiduzzaman; Zhao, Qiancheng; Krivorotov, Ilya; Nilsson, Mikael; Bagherzadeh, Nader; Boyraz, Ozdal

2017-08-01

Plasmonic nanostructures are highly used for sensing purposes since they support plasmonic modes which make them highly sensitive to the refractive index change of their surrounding medium. Therefore, they can also be used to detect changes in optical properties of ultrathin layer films in a multilayer plasmonic structure. Here, we investigate the changes in optical properties of ultrathin films of macro structures consisting of STT-RAM layers. Among the highest sensitive plasmonic structures, nanohole array has attracted many research interest because of its ease of fabrication, small footprint, and simplified optical alignment. Hence it is more suitable for defect detection in STT-RAM geometries. Moreover, the periodic nanohole pattern in the nanohole array structure makes it possible to couple the light to the surface plasmon polariton (SPP) mode supported by the structure. To assess the radiation damages and defects in STT-RAM cells we have designed a multilayer nanohole array based on the layers used in STT-RAM structure, consisting 4nm- Ta/1.5nm-CoFeB/2nm-MgO/1.5nm-CoFeB/4nm-Ta layers, all on a 300nm silver layer on top of a PEC boundary. The nanoholes go through all the layers and become closed by the PEC boundary on one side. The dimensions of the designed nanoholes are 313nm depth, 350nm diameter, and 700nm period. Here, we consider the normal incidence of light and investigate zeroth-order reflection coefficient to observe the resonance. Our simulation results show that a 10% change in refractive index of the 2nm-thick MgO layer leads to about 122GHz shift in SPP resonance in reflection pattern.

Vibration analysis of the maglev guideway with the moving load

NASA Astrophysics Data System (ADS)

Wang, H. P.; Li, J.; Zhang, K.

2007-09-01

The response of the guideway induced by moving maglev vehicle is investigated in this paper. The maglev vehicle is simplified as evenly distributed force acting on the guideway at constant speed. According to the experimental line, the guideway structure of rail-sleeper-bridge is simplified as Bernoulli-Euler (B-E) beam—evenly distributed spring—simply supported B-E beam structure; thus, double deck model of the maglev guideway is constructed which can more accurately reflect the dynamic characteristic of the experimental line. The natural frequency and mode are deduced based on the theoretical model. The relationship between structural parameters and natural frequency are exploited by employing the numerical calculation method. The way to suppress the vehicle-guideway interaction by regulating the structural parameter is also discussed here. Using the normal coordinate transformation method, the coupled differential equations of motion of the maglev guideway are converted into a set of uncoupled equations. The closed-form solutions for the response of the guideway subjecting the moving load are derived. It is noted that the moving load would not induce the vehicle-guideway interaction oscillation. The analysis of the guideway impact factor implies that at some position of the guideway, the deflection may decrease with the increase of the speed of the load; several extreme value of the guideway displacement will appear induced by different speeds, with different acting place, the speeds are different either. The final numerical simulation verifies these conclusions.

A reduced factor structure for the PROQOL-HIV questionnaire provided reliable indicators of health-related quality of life.

PubMed

Lalanne, Christophe; Chassany, Olivier; Carrieri, Patrizia; Marcellin, Fabienne; Armstrong, Andrew R; Lert, France; Spire, Bruno; Dray-Spira, Rosemary; Duracinsky, Martin

2016-04-01

To identify a simplified factor structure for the PROQOL-human immunodeficiency virus (HIV) questionnaire to improve the measurement of the health-related quality of life (HRQL) of HIV-positive patients in clinical care and research settings. HRQL data were collected using the eight-dimension PROQOL-HIV questionnaire from 2,537 patients (VESPA2 study). Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) validated a simpler four-factor structure and assessed measurement invariance (MI). Multigroup analysis assessed the effect of sex, age, and antiretroviral therapy (ART) on the resulting factor scores. Correlations with symptom and Short Form (SF)-12 self-reports assessed convergent validity. Item analysis, EFA, and CFAs confirmed the validity [comparative fit index (CFI), 0.948; root mean square error of approximation, 0.064] and reliability (α's ≥ 0.8) of four dimensions: physical health and symptoms, health concerns and mental distress, social and intimate relationships, and treatment-related impact. Strong MI was demonstrated across sex and age (decrease in CFI <0.01). A multiple-cause multiple-indicator model indicated that HRQL correlated as expected with sex, age, and the ART status. Correlations of HRQL, symptom reports, and SF-12 scores evidenced convergent validity criterion. The simplified factor structure and scoring scheme for PROQOL-HIV will allow clinicians to monitor with greater reliability the HRQL of patients in clinical care and research settings. Copyright © 2016 Elsevier Inc. All rights reserved.

What determines the spectrum of protein native state structures?

PubMed

Lezon, Timothy R; Banavar, Jayanth R; Lesk, Arthur M; Maritan, Amos

2006-05-01

We present a brief summary of the key factors underlying protein structure, as developed in the investigations of Pauling, Ramachandran, and Rose. We then outline a simplified physical model of proteins that focuses on geometry and symmetry. Although this model superficially appears unrelated to the detailed chemical descriptions commonly applied to proteins, we show that it captures the essential elements of the chemistry and provides a unified framework for understanding the common characteristics of folded proteins. We suggest that the spectrum of protein native state structures is determined by geometry and symmetry and the role of the sequence is to choose its native state structure from this predetermined menu. 2006 Wiley-Liss, Inc.

Automatic Generalizability Method of Urban Drainage Pipe Network Considering Multi-Features

NASA Astrophysics Data System (ADS)

Zhu, S.; Yang, Q.; Shao, J.

2018-05-01

Urban drainage systems are indispensable dataset for storm-flooding simulation. Given data availability and current computing power, the structure and complexity of urban drainage systems require to be simplify. However, till data, the simplify procedure mainly depend on manual operation that always leads to mistakes and lower work efficiency. This work referenced the classification methodology of road system, and proposed a conception of pipeline stroke. Further, length of pipeline, angle between two pipelines, the pipeline belonged road level and diameter of pipeline were chosen as the similarity criterion to generate the pipeline stroke. Finally, designed the automatic method to generalize drainage systems with the concern of multi-features. This technique can improve the efficiency and accuracy of the generalization of drainage systems. In addition, it is beneficial to the study of urban storm-floods.

Simplified radio-over-fiber transport systems with a low-cost multiband light source.

PubMed

Chang, Ching-Hung; Peng, Peng-Chun; Lu, Hai-Han; Shih, Chine-Liang; Chen, Hwan-Wen

2010-12-01

In this Letter, low-cost radio-over-fiber (ROF) transport systems are proposed and experimentally demonstrated. By utilizing a laser diode (LD) and a local oscillator (LO) to generate coherent multiband optical carriers, as well as a self-composed wavelength selector to separate every two carriers for different ROF transport systems, no any other dedicated LD or electrical frequency upconverting circuit/process is needed in the central station (CS). Compared with current ROF systems, the required numbers of LDs, LOs, and mixers in a CS are significantly reduced. Reducing the number of components not only can simplify the network structure but can also reduce the volume and complexity of the relative logistics. To demonstrate the practice of the proposed ROF transport systems, clear eye diagrams and error-free transmission performance are experimentally presented.

Isostatic gravity map with simplified geology of the Los Angeles 30 x 60 minute quadrangle

USGS Publications Warehouse

Wooley, R.J.; Yerkes, R.F.; Langenheim, V.E.; Chuang, F.C.

2003-01-01

This isostatic residual gravity map is part of the Southern California Areal Mapping Project (SCAMP) and is intended to promote further understanding of the geology in the Los Angeles 30 x 60 minute quadrangle, California, by serving as a basis for geophysical interpretations and by supporting both geological mapping and topical (especially earthquake) studies. Local spatial variations in the Earth's gravity field (after various corrections for elevation, terrain, and deep crustal structure explained below) reflect the lateral variation in density in the mid- to upper crust. Densities often can be related to rock type, and abrupt spatial changes in density commonly mark lithologic boundaries. The map shows contours of isostatic gravity overlain on a simplified geology including faults and rock types. The map is draped over shaded-relief topography to show landforms.

Analysis of ionospheric refraction error corrections for GRARR systems

NASA Technical Reports Server (NTRS)

Mallinckrodt, A. J.; Parker, H. C.; Berbert, J. H.

1971-01-01

A determination is presented of the ionospheric refraction correction requirements for the Goddard range and range rate (GRARR) S-band, modified S-band, very high frequency (VHF), and modified VHF systems. The relation ships within these four systems are analyzed to show that the refraction corrections are the same for all four systems and to clarify the group and phase nature of these corrections. The analysis is simplified by recognizing that the range rate is equivalent to a carrier phase range change measurement. The equation for the range errors are given.

Modeling creep behavior of fiber composites

NASA Technical Reports Server (NTRS)

Chen, J. L.; Sun, C. T.

1988-01-01

A micromechanical model for the creep behavior of fiber composites is developed based on a typical cell consisting of a fiber and the surrounding matrix. The fiber is assumed to be linearly elastic and the matrix nonlinearly viscous. The creep strain rate in the matrix is assumed to be a function of stress. The nominal stress-strain relations are derived in the form of differential equations which are solved numerically for off-axis specimens under uniaxial loading. A potential function and the associated effective stress and effective creep strain rates are introduced to simplify the orthotropic relations.

A Pilot Model for the NASA Simplified Aid for EVA Rescue (SAFER) (Single-Axis Pitch Task)

NASA Astrophysics Data System (ADS)

Handley, Patrick Mark

This thesis defines, tests, and validates a descriptive pilot model for a single-axis pitch control task of the Simplified Aid for EVA Rescue (SAFER). SAFER is a small propulsive jetpack used by astronauts for self-rescue. Pilot model research supports development of improved self-rescue strategies and technologies through insights into pilot behavior.This thesis defines a multi-loop pilot model. The innermost loop controls the hand controller, the middle loop controls pitch rate, and the outer loop controls pitch angle. A human-in-the-loop simulation was conducted to gather data from a human pilot. Quantitative and qualitative metrics both indicate that the model is an acceptable fit to the human data. Fuel consumption was nearly identical; time to task completion matched very well. There is some evidence that the model responds faster to initial pitch rates than the human, artificially decreasing the model's time to task completion. This pilot model is descriptive, not predictive, of the human pilot. Insights are made into pilot behavior from this research. Symmetry implies that the human responds to positive and negative initial conditions with the same strategy. The human pilot appears indifferent to pitch angles within 0.5 deg, coasts at a constant pitch rate 1.09 deg/s, and has a reaction delay of 0.1 s.

The foamed structures in numerical testing

NASA Astrophysics Data System (ADS)

John, Antoni; John, Małgorzata

2018-01-01

In the paper numerical simulation of the foamed metal structures using numerical homogenization algorithm is prescribed. From the beginning, numerical model of heterogeneous porous simplified structures of typical foamed metal, based on the FEM was built and material parameters (coefficients of elasticity matrix of the considered structure) were determined with use of numerical homogenization algorithm. During the work the different RVE models of structure were created and their properties were compared at different relative density, different numbers and the size and structure of the arrangement of voids. Finally, obtained results were used in modeling of typical elements made from foam metals structures - sandwich structure and profile filled with metal foam. Simulation were performed for different dimensions of cladding and core. Additionally, the test of influence material orientation (arrangement of voids in RVE element) on the maximum stresses and displacement during bending test was performed.

Highly Simplified Reddish Orange Phosphorescent Organic Light-Emitting Diodes Incorporating a Novel Carrier- and Exciton-Confining Spiro-Exciplex-Forming Host for Reduced Efficiency Roll-off.

PubMed

Xu, Ting; Zhang, Ye-Xin; Wang, Bo; Huang, Chen-Chao; Murtaza, Imran; Meng, Hong; Liao, Liang-Sheng

2017-01-25

A novel exciplex-forming host is applied so as to design highly simplified reddish orange light-emitting diodes (OLEDs) with low driving voltage, high efficiency, and an extraordinarily low efficiency roll-off, by combining N,N-10-triphenyl-10H-spiro [acridine-9,9'-fluoren]-3'-amine (SAFDPA) with 4,7-diphenyl-1,10-phenanthroline (Bphen) doped with trivalent iridium complex bis(2-methyldibenzo[f,h]quinoxaline) (acetylacetonate)iridium(III) (Ir(MDQ) 2 (acac)). The reddish orange OLEDs achieve a strikingly high power efficiency (PE) of 31.80 lm/W with an ultralow threshold voltage of 2.24 V which is almost equal to the triplet energy level of the phosphorescent reddish orange emitting dopant. The power efficiency of the device with the exciplex-forming host is enhanced, achieving 36.2% mainly owing to the lower operating voltage by the novel exciplex forming cohost, compared with the reference device (23.54 lm/W). Moreover, the OLEDs show extraordinarily low current efficiency (CE) roll-off to 1.41% at the brightness from 500 to 5000 cd/m 2 with a maximal CE of 32.87 cd/A (EQE max = 11.01%). The devices display a good reddish orange color (CIE of (0.628, 0.372) at 500 cd/m 2 ) nearly without color shift with increasing brightness. Co-host architecture phosphorescent OLEDs show a simpler device structure, lower working voltage, and a better efficiency and stability than those of the reference devices without the cohost architecture, which helps to simplify the OLED structure, lower the cost, and popularize OLED technology.

Memory functions reveal structural properties of gene regulatory networks

PubMed Central

Perez-Carrasco, Ruben

2018-01-01

Gene regulatory networks (GRNs) control cellular function and decision making during tissue development and homeostasis. Mathematical tools based on dynamical systems theory are often used to model these networks, but the size and complexity of these models mean that their behaviour is not always intuitive and the underlying mechanisms can be difficult to decipher. For this reason, methods that simplify and aid exploration of complex networks are necessary. To this end we develop a broadly applicable form of the Zwanzig-Mori projection. By first converting a thermodynamic state ensemble model of gene regulation into mass action reactions we derive a general method that produces a set of time evolution equations for a subset of components of a network. The influence of the rest of the network, the bulk, is captured by memory functions that describe how the subnetwork reacts to its own past state via components in the bulk. These memory functions provide probes of near-steady state dynamics, revealing information not easily accessible otherwise. We illustrate the method on a simple cross-repressive transcriptional motif to show that memory functions not only simplify the analysis of the subnetwork but also have a natural interpretation. We then apply the approach to a GRN from the vertebrate neural tube, a well characterised developmental transcriptional network composed of four interacting transcription factors. The memory functions reveal the function of specific links within the neural tube network and identify features of the regulatory structure that specifically increase the robustness of the network to initial conditions. Taken together, the study provides evidence that Zwanzig-Mori projections offer powerful and effective tools for simplifying and exploring the behaviour of GRNs. PMID:29470492