Lumped Parameter Model (LPM) for Light-Duty Vehicles

EPA Pesticide Factsheets

EPA’s Lumped Parameter Model (LPM) is a free, desktop computer application that estimates the effectiveness (CO2 Reduction) of various technology combinations or “packages,” in a manner that accounts for synergies between technologies.

Finite element simulation of piezoelectric transformers.

PubMed

Tsuchiya, T; Kagawa, Y; Wakatsuki, N; Okamura, H

2001-07-01

Piezoelectric transformers are nothing but ultrasonic resonators with two pairs of electrodes provided on the surface of a piezoelectric substrate in which electrical energy is carried in the mechanical form. The input and output electrodes are arranged to provide the impedance transformation, which results in the voltage transformation. As they are operated at a resonance, the electrical equivalent circuit approach has traditionally been developed in a rather empirical way and has been used for analysis and design. The present paper deals with the analysis of the piezoelectric transformers based on the three-dimensional finite element modelling. The PIEZO3D code that we have developed is modified to include the external loading conditions. The finite element approach is now available for a wide variety of the electrical boundary conditions. The equivalent circuit of lumped parameters can also be derived from the finite element method (FEM) solution if required. The simulation of the present transformers is made for the low intensity operation and compared with the experimental results. Demonstration is made for basic Rosen-type transformers in which the longitudinal mode of a plate plays an important role; in which the equivalent circuit of lumped constants has been used. However, there are many modes of vibration associated with the plate, the effect of which cannot always be ignored. In the experiment, the double resonances are sometimes observed in the vicinity of the operating frequency. The simulation demonstrates that this is due to the coupling of the longitudinal mode with the flexural mode. Thus, the simulation provides an invaluable guideline to the transformer design.

Note: A calibration method to determine the lumped-circuit parameters of a magnetic probe.

PubMed

Li, Fuming; Chen, Zhipeng; Zhu, Lizhi; Liu, Hai; Wang, Zhijiang; Zhuang, Ge

2016-06-01

This paper describes a novel method to determine the lumped-circuit parameters of a magnetic inductive probe for calibration by using Helmholtz coils with high frequency power supply (frequency range: 10 kHz-400 kHz). The whole calibration circuit system can be separated into two parts: "generator" circuit and "receiver" circuit. By implementing the Fourier transform, two analytical lumped-circuit models, with respect to these separated circuits, are constructed to obtain the transfer function between each other. Herein, the precise lumped-circuit parameters (including the resistance, inductance, and capacitance) of the magnetic probe can be determined by fitting the experimental data to the transfer function. Regarding the fitting results, the finite impedance of magnetic probe can be used to analyze the transmission of a high-frequency signal between magnetic probes, cables, and acquisition system.

A distributed parameter model of transmission line transformer for high voltage nanosecond pulse generation

NASA Astrophysics Data System (ADS)

Li, Jiangtao; Zhao, Zheng; Li, Longjie; He, Jiaxin; Li, Chenjie; Wang, Yifeng; Su, Can

2017-09-01

A transmission line transformer has potential advantages for nanosecond pulse generation including excellent frequency response and no leakage inductance. The wave propagation process in a secondary mode line is indispensable due to an obvious inside transient electromagnetic transition in this scenario. The equivalent model of the transmission line transformer is crucial for predicting the output waveform and evaluating the effects of magnetic cores on output performance. However, traditional lumped parameter models are not sufficient for nanosecond pulse generation due to the natural neglect of wave propagations in secondary mode lines based on a lumped parameter assumption. In this paper, a distributed parameter model of transmission line transformer was established to investigate wave propagation in the secondary mode line and its influential factors through theoretical analysis and experimental verification. The wave propagation discontinuity in the secondary mode line induced by magnetic cores is emphasized. Characteristics of the magnetic core under a nanosecond pulse were obtained by experiments. Distribution and formation of the secondary mode current were determined for revealing essential wave propagation processes in secondary mode lines. The output waveform and efficiency were found to be affected dramatically by wave propagation discontinuity in secondary mode lines induced by magnetic cores. The proposed distributed parameter model was proved more suitable for nanosecond pulse generation in aspects of secondary mode current, output efficiency, and output waveform. In depth, comprehension of underlying mechanisms and a broader view of the working principle of the transmission line transformer for nanosecond pulse generation can be obtained through this research.

A distributed parameter model of transmission line transformer for high voltage nanosecond pulse generation.

PubMed

Li, Jiangtao; Zhao, Zheng; Li, Longjie; He, Jiaxin; Li, Chenjie; Wang, Yifeng; Su, Can

2017-09-01

A transmission line transformer has potential advantages for nanosecond pulse generation including excellent frequency response and no leakage inductance. The wave propagation process in a secondary mode line is indispensable due to an obvious inside transient electromagnetic transition in this scenario. The equivalent model of the transmission line transformer is crucial for predicting the output waveform and evaluating the effects of magnetic cores on output performance. However, traditional lumped parameter models are not sufficient for nanosecond pulse generation due to the natural neglect of wave propagations in secondary mode lines based on a lumped parameter assumption. In this paper, a distributed parameter model of transmission line transformer was established to investigate wave propagation in the secondary mode line and its influential factors through theoretical analysis and experimental verification. The wave propagation discontinuity in the secondary mode line induced by magnetic cores is emphasized. Characteristics of the magnetic core under a nanosecond pulse were obtained by experiments. Distribution and formation of the secondary mode current were determined for revealing essential wave propagation processes in secondary mode lines. The output waveform and efficiency were found to be affected dramatically by wave propagation discontinuity in secondary mode lines induced by magnetic cores. The proposed distributed parameter model was proved more suitable for nanosecond pulse generation in aspects of secondary mode current, output efficiency, and output waveform. In depth, comprehension of underlying mechanisms and a broader view of the working principle of the transmission line transformer for nanosecond pulse generation can be obtained through this research.

WATGIS: A GIS-Based Lumped Parameter Water Quality Model

Treesearch

Glenn P. Fernandez; George M. Chescheir; R. Wayne Skaggs; Devendra M. Amatya

2002-01-01

A Geographic Information System (GIS)­based, lumped parameter water quality model was developed to estimate the spatial and temporal nitrogen­loading patterns for lower coastal plain watersheds in eastern North Carolina. The model uses a spatially distributed delivery ratio (DR) parameter to account for nitrogen retention or loss along a drainage network. Delivery...

Lump solutions with interaction phenomena in the (2+1)-dimensional Ito equation

NASA Astrophysics Data System (ADS)

Zou, Li; Yu, Zong-Bing; Tian, Shou-Fu; Feng, Lian-Li; Li, Jin

2018-03-01

In this paper, we consider the (2+1)-dimensional Ito equation, which was introduced by Ito. By considering the Hirota’s bilinear method, and using the positive quadratic function, we obtain some lump solutions of the Ito equation. In order to ensure rational localization and analyticity of these lump solutions, some sufficient and necessary conditions are provided on the parameters that appeared in the solutions. Furthermore, the interaction solutions between lump solutions and the stripe solitons are discussed by combining positive quadratic function with exponential function. Finally, the dynamic properties of these solutions are shown via the way of graphical analysis by selecting appropriate values of the parameters.

Design Optimization Tool for Synthetic Jet Actuators Using Lumped Element Modeling

NASA Technical Reports Server (NTRS)

Gallas, Quentin; Sheplak, Mark; Cattafesta, Louis N., III; Gorton, Susan A. (Technical Monitor)

2005-01-01

The performance specifications of any actuator are quantified in terms of an exhaustive list of parameters such as bandwidth, output control authority, etc. Flow-control applications benefit from a known actuator frequency response function that relates the input voltage to the output property of interest (e.g., maximum velocity, volumetric flow rate, momentum flux, etc.). Clearly, the required performance metrics are application specific, and methods are needed to achieve the optimal design of these devices. Design and optimization studies have been conducted for piezoelectric cantilever-type flow control actuators, but the modeling issues are simpler compared to synthetic jets. Here, lumped element modeling (LEM) is combined with equivalent circuit representations to estimate the nonlinear dynamic response of a synthetic jet as a function of device dimensions, material properties, and external flow conditions. These models provide reasonable agreement between predicted and measured frequency response functions and thus are suitable for use as design tools. In this work, we have developed a Matlab-based design optimization tool for piezoelectric synthetic jet actuators based on the lumped element models mentioned above. Significant improvements were achieved by optimizing the piezoceramic diaphragm dimensions. Synthetic-jet actuators were fabricated and benchtop tested to fully document their behavior and validate a companion optimization effort. It is hoped that the tool developed from this investigation will assist in the design and deployment of these actuators.

Electromechanical coupling factor of capacitive micromachined ultrasonic transducers.

PubMed

Caronti, Alessandro; Carotenuto, Riccardo; Pappalardo, Massimo

2003-01-01

Recently, a linear, analytical distributed model for capacitive micromachined ultrasonic transducers (CMUTs) was presented, and an electromechanical equivalent circuit based on the theory reported was used to describe the behavior of the transducer [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 49, 159-168 (2002)]. The distributed model is applied here to calculate the dynamic coupling factor k(w) of a lossless CMUT, based on a definition that involves the energies stored in a dynamic vibration cycle, and the results are compared with those obtained with a lumped model. A strong discrepancy is found between the two models as the bias voltage increases. The lumped model predicts an increasing dynamic k factor up to unity, whereas the distributed model predicts a more realistic saturation of this parameter to values substantially lower. It is demonstrated that the maximum value of k(w), corresponding to an operating point close to the diaphragm collapse, is 0.4 for a CMUT single cell with a circular membrane diaphragm and no parasitic capacitance (0.36 for a cell with a circular plate diaphragm). This means that the dynamic coupling factor of a CMUT is comparable to that of a piezoceramic plate oscillating in the thickness mode. Parasitic capacitance decreases the value of k(w), because it does not contribute to the energy conversion. The effective coupling factor k(eff) is also investigated, showing that this parameter coincides with k(w) within the lumped model approximation, but a quite different result is obtained if a computation is made with the more accurate distributed model. As a consequence, k(eff), which can be measured from the transducer electrical impedance, does not give a reliable value of the actual dynamic coupling factor.

Electromechanical coupling factor of capacitive micromachined ultrasonic transducers

NASA Astrophysics Data System (ADS)

Caronti, Alessandro; Carotenuto, Riccardo; Pappalardo, Massimo

2003-01-01

Recently, a linear, analytical distributed model for capacitive micromachined ultrasonic transducers (CMUTs) was presented, and an electromechanical equivalent circuit based on the theory reported was used to describe the behavior of the transducer [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 49, 159-168 (2002)]. The distributed model is applied here to calculate the dynamic coupling factor kw of a lossless CMUT, based on a definition that involves the energies stored in a dynamic vibration cycle, and the results are compared with those obtained with a lumped model. A strong discrepancy is found between the two models as the bias voltage increases. The lumped model predicts an increasing dynamic k factor up to unity, whereas the distributed model predicts a more realistic saturation of this parameter to values substantially lower. It is demonstrated that the maximum value of kw, corresponding to an operating point close to the diaphragm collapse, is 0.4 for a CMUT single cell with a circular membrane diaphragm and no parasitic capacitance (0.36 for a cell with a circular plate diaphragm). This means that the dynamic coupling factor of a CMUT is comparable to that of a piezoceramic plate oscillating in the thickness mode. Parasitic capacitance decreases the value of kw, because it does not contribute to the energy conversion. The effective coupling factor keff is also investigated, showing that this parameter coincides with kw within the lumped model approximation, but a quite different result is obtained if a computation is made with the more accurate distributed model. As a consequence, keff, which can be measured from the transducer electrical impedance, does not give a reliable value of the actual dynamic coupling factor.

Rogue waves and lump solitons for a ?-dimensional B-type Kadomtsev-Petviashvili equation in fluid dynamics

NASA Astrophysics Data System (ADS)

Sun, Yan; Tian, Bo; Xie, Xi-Yang; Chai, Jun; Yin, Hui-Min

2018-07-01

Under investigation is a ?-dimensional B-type Kadomtsev-Petviashvili equation, which has applications in the propagation of non-linear waves in fluid dynamics. Through the Hirota method and the extended homoclinic test technique, we obtain the breather-type kink soliton solutions and breather rational soliton solutions. Rogue wave solutions are derived, which come from the derivation of breather rational solitons with respect to x. Amplitudes of the breather-type kink solitons and rogue waves decrease with a non-zero parameter in the equation, ?, increasing when ?. In addition, dark rogue waves are derived when ?. Furthermore, with the aid of the Hirota method and symbolic computation, two types of the lump solitons are obtained with the different choices of the parameters. We graphically study the lump solitons related to the parameter ?, and amplitude of the lump soliton is negatively correlated with ? when ?.

DRAINMOD-GIS: a lumped parameter watershed scale drainage and water quality model

Treesearch

G.P. Fernandez; G.M. Chescheir; R.W. Skaggs; D.M. Amatya

2006-01-01

A watershed scale lumped parameter hydrology and water quality model that includes an uncertainty analysis component was developed and tested on a lower coastal plain watershed in North Carolina. Uncertainty analysis was used to determine the impacts of uncertainty in field and network parameters of the model on the predicted outflows and nitrate-nitrogen loads at the...

Performance analysis of FET microwave devices by use of extended spectral-element time-domain method

NASA Astrophysics Data System (ADS)

Sheng, Yijun; Xu, Kan; Wang, Daoxiang; Chen, Rushan

2013-05-01

The extended spectral-element time-domain (SETD) method is employed to analyse field effect transistor (FET) microwave devices. In order to impose the contribution of the FET microwave devices into the electromagnetic simulation, the SETD method is extended by introducing a lumped current term into the vector Helmholtz equation. The change of currents on each lumped component can be expressed by the change of voltage via corresponding models of equivalent circuit. The electric fields around the lumped component must be influenced by the change of voltage on each lumped component, and vice versa. So a global coupling about the EM-circuit can be built directly. The fully explicit solving scheme is maintained in this extended SETD method and the CPU time can be saved spontaneously. Three practical FET microwave devices are analysed in this article. The numerical results demonstrate the ability and accuracy of this method.

Compact lumped circuit model of discharges in DC accelerator using partial element equivalent circuit

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

Banerjee, Srutarshi; Rajan, Rehim N.; Singh, Sandeep K.

2014-07-01

DC Accelerators undergoes different types of discharges during its operation. A model depicting the discharges has been simulated to study the different transient conditions. The paper presents a Physics based approach of developing a compact circuit model of the DC Accelerator using Partial Element Equivalent Circuit (PEEC) technique. The equivalent RLC model aids in analyzing the transient behavior of the system and predicting anomalies in the system. The electrical discharges and its properties prevailing in the accelerator can be evaluated by this equivalent model. A parallel coupled voltage multiplier structure is simulated in small scale using few stages of coronamore » guards and the theoretical and practical results are compared. The PEEC technique leads to a simple model for studying the fault conditions in accelerator systems. Compared to the Finite Element Techniques, this technique gives the circuital representation. The lumped components of the PEEC are used to obtain the input impedance and the result is also compared to that of the FEM technique for a frequency range of (0-200) MHz. (author)« less

Lump Solutions and Interaction Phenomenon for (2+1)-Dimensional Sawada-Kotera Equation

NASA Astrophysics Data System (ADS)

Huang, Li-Li; Chen, Yong

2017-05-01

In this paper, a class of lump solutions to the (2+1)-dimensional Sawada-Kotera equation is studied by searching for positive quadratic function solutions to the associated bilinear equation. To guarantee rational localization and analyticity of the lumps, some sufficient and necessary conditions are presented on the parameters involved in the solutions. Then, a completely non-elastic interaction between a lump and a stripe of the (2+1)-dimensional Sawada-Kotera equation is obtained, which shows a lump solution is drowned or swallowed by a stripe soliton. Finally, 2-dimensional curves, 3-dimensional plots and density plots with particular choices of the involved parameters are presented to show the dynamic characteristics of the obtained lump and interaction solutions. Supported by the Global Change Research Program of China under Grant No. 2015CB953904, National Natural Science Foundation of China under Grant Nos. 11675054 and 11435005, Outstanding Doctoral Dissertation Cultivation Plan of Action under Grant No. YB2016039, and Shanghai Collaborative Innovation Center of Trustworthy Software for Internet of Things under Grant No. ZF1213

Lumped Parameter Modeling for Rapid Vibration Response Prototyping and Test Correlation for Electronic Units

NASA Technical Reports Server (NTRS)

Van Dyke, Michael B.

2013-01-01

Present preliminary work using lumped parameter models to approximate dynamic response of electronic units to random vibration; Derive a general N-DOF model for application to electronic units; Illustrate parametric influence of model parameters; Implication of coupled dynamics for unit/board design; Demonstrate use of model to infer printed wiring board (PWB) dynamics from external chassis test measurement.

Ultrabroadband Microwave Metamaterial Absorber Based on Electric SRR Loaded with Lumped Resistors

NASA Astrophysics Data System (ADS)

Zhao, Jingcheng; Cheng, Yongzhi

2016-10-01

An ultrabroadband microwave metamaterial absorber (MMA) based on an electric split-ring resonator (ESRR) loaded with lumped resistors is presented. Compared with an ESRR MMA, the composite MMA (CMMA) loaded with lumped resistors offers stronger absorption over an extremely extended bandwidth. The reflectance simulated under different substrate loss conditions indicates that incident electromagnetic (EM) wave energy is mainly consumed by the lumped resistors. The simulated surface current and power loss density distributions further illustrate the mechanism underlying the observed absorption. Further simulation results indicate that the performance of the CMMA can be tuned by adjusting structural parameters of the ESRR and lumped resistor parameters. We fabricated and measured MMA and CMMA samples. The CMMA yielded below -10 dB reflectance from 4.4 GHz to 18 GHz experimentally, with absorption bandwidth and relative bandwidth of 13.6 GHz and 121.4%, respectively. This ultrabroadband microwave absorber has potential applications in the electromagnetic energy harvesting and stealth fields.

Roles of epsilon-near-zero (ENZ) and mu-near-zero (MNZ) materials in optical metatronic circuit networks.

PubMed

Abbasi, Fereshteh; Engheta, Nader

2014-10-20

The concept of metamaterial-inspired nanocircuits, dubbed metatronics, was introduced in [Science 317, 1698 (2007); Phys. Rev. Lett. 95, 095504 (2005)]. It was suggested how optical lumped elements (nanoelements) can be made using subwavelength plasmonic or non-plasmonic particles. As a result, the optical metatronic equivalents of a number of electronic circuits, such as frequency mixers and filters, were suggested. In this work we further expand the concept of electronic lumped element networks into optical metatronic circuits and suggest a conceptual model applicable to various metatronic passive networks. In particular, we differentiate between the series and parallel networks using epsilon-near-zero (ENZ) and mu-near-zero (MNZ) materials. We employ layered structures with subwavelength thicknesses for the nanoelements as the building blocks of collections of metatronic networks. Furthermore, we explore how by choosing the non-zero constitutive parameters of the materials with specific dispersions, either Drude or Lorentzian dispersion with suitable parameters, capacitive and inductive responses can be achieved in both series and parallel networks. Next, we proceed with the one-to-one analogy between electronic circuits and optical metatronic filter layered networks and justify our analogies by comparing the frequency response of the two paradigms. Finally, we examine the material dispersion of near-zero relative permittivity as well as other physically important material considerations such as losses.

Lumped Model Generation and Evaluation: Sensitivity and Lie Algebraic Techniques with Applications to Combustion

DTIC Science & Technology

1989-03-03

address global parameter space mapping issues for first order differential equations. The rigorous criteria for the existence of exact lumping by linear projective transformations was also established.

Steady-state, lumped-parameter model for capacitor-run, single-phase induction motors

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

Umans, S.D.

1996-01-01

This paper documents a technique for deriving a steady-state, lumped-parameter model for capacitor-run, single-phase induction motors. The objective of this model is to predict motor performance parameters such as torque, loss distribution, and efficiency as a function of applied voltage and motor speed as well as the temperatures of the stator windings and of the rotor. The model includes representations of both the main and auxiliary windings (including arbitrary external impedances) and also the effects of core and rotational losses. The technique can be easily implemented and the resultant model can be used in a wide variety of analyses tomore » investigate motor performance as a function of load, speed, and winding and rotor temperatures. The technique is based upon a coupled-circuit representation of the induction motor. A notable feature of the model is the technique used for representing core loss. In equivalent-circuit representations of transformers and induction motors, core loss is typically represented by a core-loss resistance in shunt with the magnetizing inductance. In order to maintain the coupled-circuit viewpoint adopted in this paper, this technique was modified slightly; core loss is represented by a set of core-loss resistances connected to the ``secondaries`` of a set of windings which perfectly couple to the air-gap flux of the motor. An example of the technique is presented based upon a 3.5 kW, single-phase, capacitor-run motor and the validity of the technique is demonstrated by comparing predicted and measured motor performance.« less

Calibrating binary lumped parameter models

NASA Astrophysics Data System (ADS)

Morgenstern, Uwe; Stewart, Mike

2017-04-01

Groundwater at its discharge point is a mixture of water from short and long flowlines, and therefore has a distribution of ages rather than a single age. Various transfer functions describe the distribution of ages within the water sample. Lumped parameter models (LPMs), which are mathematical models of water transport based on simplified aquifer geometry and flow configuration can account for such mixing of groundwater of different age, usually representing the age distribution with two parameters, the mean residence time, and the mixing parameter. Simple lumped parameter models can often match well the measured time varying age tracer concentrations, and therefore are a good representation of the groundwater mixing at these sites. Usually a few tracer data (time series and/or multi-tracer) can constrain both parameters. With the building of larger data sets of age tracer data throughout New Zealand, including tritium, SF6, CFCs, and recently Halon-1301, and time series of these tracers, we realised that for a number of wells the groundwater ages using a simple lumped parameter model were inconsistent between the different tracer methods. Contamination or degradation of individual tracers is unlikely because the different tracers show consistent trends over years and decades. This points toward a more complex mixing of groundwaters with different ages for such wells than represented by the simple lumped parameter models. Binary (or compound) mixing models are able to represent a more complex mixing, with mixing of water of two different age distributions. The problem related to these models is that they usually have 5 parameters which makes them data-hungry and therefore difficult to constrain all parameters. Two or more age tracers with different input functions, with multiple measurements over time, can provide the required information to constrain the parameters of the binary mixing model. We obtained excellent results using tritium time series encompassing the passage of the bomb-tritium through the aquifer, and SF6 with its steep gradient currently in the input. We will show age tracer data from drinking water wells that enabled identification of young water ingression into wells, which poses the risk of bacteriological contamination from the surface into the drinking water.

Measurement of Hydrologic Streamflow Metrics and Estimation of Streamflow with Lumped Parameter Models in a Managed Lake System, Sebago Lake, Maine

NASA Astrophysics Data System (ADS)

Reeve, A. S.; Martin, D.; Smith, S. M.

2013-12-01

Surface waters within the Sebago Lake watershed (southern Maine, USA) provide a variety of economically and intrinsically valuable recreational, commercial and environmental services. Different stakeholder groups for the 118 km2 Sebago Lake and surrounding watershed advocate for different lake and watershed management strategies, focusing on the operation of a dam at the outflow from Sebago Lake. While lake level in Sebago Lake has been monitored for over a century, limited data is available on the hydrologic processes that drive lake level and therefore impact how dam operation (and other changes to the region) will influence the hydroperiod of the lake. To fill this information gap several tasks were undertaken including: 1) deploying data logging pressure transducers to continuously monitor stream stage in nine tributaries, 2) measuring stream discharge at these sites to create rating curves for the nine tributaries, and using the resulting continuous discharge records to 3) calibrate lumped parameter computer models based on the GR4J model, modified to include a degree-day snowmelt routine. These lumped parameter models have been integrated with a simple lake water-balance model to estimate lake level and its response to different scenarios including dam management strategies. To date, about three years of stream stage data have been used to estimate stream discharge in all monitored tributaries (data collection is ongoing). Baseflow separation indices (BFI) for 2010 and 2011 using the USGS software PART and the Eckhart digital filter in WHAT range from 0.80-0.86 in the Crooked River and Richmill Outlet,followed by Northwest (0.75) and Muddy (0.53-0.56) Rivers, with the lowest BFI measured in Sticky River (0.41-0.56). The BFI values indicate most streams have significant groundwater (or other storage) inputs. The lumped parameter watershed model has been calibrated for four streams (Nash-Sutcliffe = 0.4 to 0.9), with the other major tributaries containing hydraulic structures that are not included in the lumped parameter model. Calibrated watershed models tend to substantially underestimate the highest streamflows while overestimating low flows. An early June 2012 event caused extremely high flows with discharge in the Crooked River (the most significant tributary) peaking at about 85 m3/day. The lumped parameter model dramatically underestimated this important and anomalous event, but provided a reasonable prediction of flows throughout the rest of 2012. Ongoing work includes incorporating hydraulic structures in the lumped parameter model and using the available data to drive the lake water-balance model that has been prepared.

Deflection Analysis of the Space Shuttle External Tank Door Drive Mechanism

NASA Technical Reports Server (NTRS)

Tosto, Michael A.; Trieu, Bo C.; Evernden, Brent A.; Hope, Drew J.; Wong, Kenneth A.; Lindberg, Robert E.

2008-01-01

Upon observing an abnormal closure of the Space Shuttle s External Tank Doors (ETD), a dynamic model was created in MSC/ADAMS to conduct deflection analyses for assessing whether the Door Drive Mechanism (DDM) was subjected to excessive additional stress, and more importantly, to evaluate the magnitude of the induced step or gap with respect to shuttle s body tiles. To model the flexibility of the DDM, a lumped parameter approximation was used to capture the compliance of individual parts within the drive linkage. These stiffness approximations were then validated using FEA and iteratively updated in the model to converge on the actual distributed parameter equivalent stiffnesses. The goal of the analyses is to determine the deflections in the mechanism and whether or not the deflections are in the region of elastic or plastic deformation. Plastic deformation may affect proper closure of the ETD and would impact aero-heating during re-entry.

The generation of symmetric and asymmetric lump solitons by a bottom topography

NASA Astrophysics Data System (ADS)

Lu, Zhiming

2016-11-01

A group of Lump solutions to the (2+1)-dimensional Kadomtsev-Petviashvili (KP) equation is obtained analytically by making use of Hirota bilinear transform method. Then the generation of symmetric and asymmetric lump solitons by an obliquely-placed three-dimensional bottom topography is numerically investigated using the forced Kadomtsev-Petviashvili-I (fKP-I) equation. The numerical method is based on the third order Runge-Kutta method and the Crank-Nicolson scheme. The main result is the asymmetric generation of asymmetric lump-type solitons downstream of the obstacle.The lump soliton with a smaller amplitude is generated with a longer period and moves in a larger angle with respect to the positive x-axis than the one with a larger amplitude. The amplitude of the lump solitons strongly depend on the volume of the obstacle rather than the shape. Finally the effects of the detuning parameter on the generation of lump solitons is also studied. Project supported by NSFC with No. 11272196.

Simplified microstrip discontinuity modeling using the transmission line matrix method interfaced to microwave CAD

NASA Astrophysics Data System (ADS)

Thompson, James H.; Apel, Thomas R.

1990-07-01

A technique for modeling microstrip discontinuities is presented which is derived from the transmission line matrix method of solving three-dimensional electromagnetic problems. In this technique the microstrip patch under investigation is divided into an integer number of square and half-square (triangle) subsections. An equivalent lumped-element model is calculated for each subsection. These individual models are then interconnected as dictated by the geometry of the patch. The matrix of lumped elements is then solved using either of two microwave CAD software interfaces with each port properly defined. Closed-form expressions for the lumped-element representation of the individual subsections is presented and experimentally verified through the X-band frequency range. A model demonstrating the use of symmetry and block construction of a circuit element is discussed, along with computer program development and CAD software interface.

A continuous-discrete approach for evaluation of natural frequencies and mode shapes of high-rise buildings

NASA Astrophysics Data System (ADS)

Malekinejad, Mohsen; Rahgozar, Reza; Malekinejad, Ali; Rahgozar, Peyman

2016-09-01

In this paper, a continuous-discrete approach based on the concept of lumped mass and equivalent continuous approach is proposed for free vibration analysis of combined system of framed tube, shear core and outrigger-belt truss in high-rise buildings. This system is treated as a continuous system (i.e., discrete beams and columns are replaced with equivalent continuous membranes) and a discrete system (or lumped mass system) at different stages of dynamic analysis. The structure is discretized at each floor of the building as a series of lumped masses placed at the center of shear core. Each mass has two transitional degrees of freedom (lateral and axial( and one rotational. The effect of shear core and outrigger-belt truss on framed tube system is modeled as a rotational spring placed at the location of outrigger-belt truss system along structure's height. By solving the resulting eigen problem, natural frequencies and mode-shapes are obtained. Numerical examples are presented to show acceptable accuracy of the procedure in estimating the fundamental frequencies and corresponding mode shapes of the combined system as compared to finite element analysis of the complete structure. The simplified proposed method is much faster and should be more suitable for rapid interactive design.

Emergence and space-time structure of lump solution to the (2+1)-dimensional generalized KP equation

NASA Astrophysics Data System (ADS)

Tan, Wei; Dai, Houping; Dai, Zhengde; Zhong, Wenyong

2017-11-01

A periodic breather-wave solution is obtained using homoclinic test approach and Hirota's bilinear method with a small perturbation parameter u0 for the (2+1)-dimensional generalized Kadomtsev-Petviashvili equation. Based on the periodic breather-wave, a lump solution is emerged by limit behaviour. Finally, three different forms of the space-time structure of the lump solution are investigated and discussed using the extreme value theory.

Rogue waves and lump solutions for a (3+1)-dimensional generalized B-type Kadomtsev-Petviashvili equation in fluid mechanics

NASA Astrophysics Data System (ADS)

Wu, Xiao-Yu; Tian, Bo; Chai, Han-Peng; Sun, Yan

2017-08-01

Under investigation in this letter is a (3+1)-dimensional generalized B-type Kadomtsev-Petviashvili equation, which describes the weakly dispersive waves propagating in a fluid. Employing the Hirota method and symbolic computation, we obtain the lump, breather-wave and rogue-wave solutions under certain constraints. We graphically study the lump waves with the influence of the parameters h1, h3 and h5 which are all the real constants: When h1 increases, amplitude of the lump wave increases, and location of the peak moves; when h3 increases, lump wave’s amplitude decreases, but location of the peak keeps unchanged; when h5 changes, lump wave’s peak location moves, but amplitude keeps unchanged. Breather waves and rogue waves are displayed: Rogue waves emerge when the periods of the breather waves go to the infinity.

Comparison of particle-tracking and lumped-parameter age-distribution models for evaluating vulnerability of production wells to contamination

USGS Publications Warehouse

Eberts, S.M.; Böhlke, J.K.; Kauffman, L.J.; Jurgens, B.C.

2012-01-01

Environmental age tracers have been used in various ways to help assess vulnerability of drinking-water production wells to contamination. The most appropriate approach will depend on the information that is available and that which is desired. To understand how the well will respond to changing nonpoint-source contaminant inputs at the water table, some representation of the distribution of groundwater ages in the well is needed. Such information for production wells is sparse and difficult to obtain, especially in areas lacking detailed field studies. In this study, age distributions derived from detailed groundwater-flow models with advective particle tracking were compared with those generated from lumped-parameter models to examine conditions in which estimates from simpler, less resource-intensive lumped-parameter models could be used in place of estimates from particle-tracking models. In each of four contrasting hydrogeologic settings in the USA, particle-tracking and lumped-parameter models yielded roughly similar age distributions and largely indistinguishable contaminant trends when based on similar conceptual models and calibrated to similar tracer data. Although model calibrations and predictions were variably affected by tracer limitations and conceptual ambiguities, results illustrated the importance of full age distributions, rather than apparent tracer ages or model mean ages, for trend analysis and forecasting.

Parametric excitation of tire-wheel assemblies by a stiffness non-uniformity

NASA Astrophysics Data System (ADS)

Stutts, D. S.; Krousgrill, C. M.; Soedel, W.

1995-01-01

A simple model of the effect of a concentrated radial stiffness non-uniformity in a passenger car tire is presented. The model treats the tread band of the tire as a rigid ring supported on a viscoelastic foundation. The distributed radial stiffness is lumped into equivalent horizontal (fore-and-aft) and vertical stiffnesses. The concentrated radial stiffness non-uniformity is modeled by treating the tread band as fixed, and the stiffness non-uniformity as rotating around it at the nominal angular velocity of the wheel. Due to loading, the center of mass of the tread band ring model is displaced upward with respect to the wheel spindle and, therefore, the rotating stiffness non-uniformity is alternately compressed and stretched through one complete rotation. This stretching and compressing of the stiffness non-uniformity results in force transmission to the wheel spindle at twice the nominal angular velocity in frequency, and therefore, would excite a given resonance at one-half the nominal angular wheel velocity that a mass unbalance would. The forcing produced by the stiffness non-uniformity is parametric in nature, thus creating the possibility of parametric resonance. The basic theory of the parametric resonance is explained, and a parameter study using derived lumped parameters based on a typical passenger car tire is performed. This study revealed that parametric resonance in passenger car tires, although possible, is unlikely at normal highway speeds as predicted by this model unless the tire is partially deflated.

A comparison of two approaches to modelling snow cover dynamics at the Polish Polar Station at Hornsund

NASA Astrophysics Data System (ADS)

Luks, B.; Osuch, M.; Romanowicz, R. J.

2012-04-01

We compare two approaches to modelling snow cover dynamics at the Polish Polar Station at Hornsund. In the first approach we apply physically-based Utah Energy Balance Snow Accumulation and Melt Model (UEB) (Tarboton et al., 1995; Tarboton and Luce, 1996). The model uses a lumped representation of the snowpack with two primary state variables: snow water equivalence and energy. Its main driving inputs are: air temperature, precipitation, wind speed, humidity and radiation (estimated from the diurnal temperature range). Those variables are used for physically-based calculations of radiative, sensible, latent and advective heat exchanges with a 3 hours time step. The second method is an application of a statistically efficient lumped parameter time series approach to modelling the dynamics of snow cover , based on daily meteorological measurements from the same area. A dynamic Stochastic Transfer Function model is developed that follows the Data Based Mechanistic approach, where a stochastic data-based identification of model structure and an estimation of its parameters are followed by a physical interpretation. We focus on the analysis of uncertainty of both model outputs. In the time series approach, the applied techniques also provide estimates of the modeling errors and the uncertainty of the model parameters. In the first, physically-based approach the applied UEB model is deterministic. It assumes that the observations are without errors and that the model structure perfectly describes the processes within the snowpack. To take into account the model and observation errors, we applied a version of the Generalized Likelihood Uncertainty Estimation technique (GLUE). This technique also provide estimates of the modelling errors and the uncertainty of the model parameters. The observed snowpack water equivalent values are compared with those simulated with 95% confidence bounds. This work was supported by National Science Centre of Poland (grant no. 7879/B/P01/2011/40). Tarboton, D. G., T. G. Chowdhury and T. H. Jackson, 1995. A Spatially Distributed Energy Balance Snowmelt Model. In K. A. Tonnessen, M. W. Williams and M. Tranter (Ed.), Proceedings of a Boulder Symposium, July 3-14, IAHS Publ. no. 228, pp. 141-155. Tarboton, D. G. and C. H. Luce, 1996. Utah Energy Balance Snow Accumulation and Melt Model (UEB). Computer model technical description and users guide, Utah Water Research Laboratory and USDA Forest Service Intermountain Research Station (http://www.engineering.usu.edu/dtarb/). 64 pp.

Whirling and stability of flywheel systems, part I: Derivation of combined and lumped parameter models

NASA Astrophysics Data System (ADS)

Ramanujam, G.; Bert, C. W.

1983-06-01

The objective of this paper is to provide a theoretical foundation to predict many aspects of dynamic behavior of flywheel systems when spin-tested with a quill shaft support and driven by an air turbine. Theoretical analyses for the following are presented: (1) determination of natural frequencies (or for brevity critical speeds of various orders), (2) Routh-type stability analysis to determine the stability limits (i.e., the speed range within which small perturbations attenuate rather than cause catastrophic failure), and (3) forced whirling analysis to estimate the response of major components of the system to flywheel mass eccentricity and initial tilt. For the first and third kinds of analyses, two different mathematical models of the generic system are investigated. One is a seven-degree-of-freedom lumped parameter analysis, while the other is a combined distributed and lumped parameter analysis.

Stabilization and synchronization for a mechanical system via adaptive sliding mode control.

PubMed

Song, Zhankui; Sun, Kaibiao; Ling, Shuai

2017-05-01

In this paper, we investigate the synchronization problem of chaotic centrifugal flywheel governor with parameters uncertainty and lumped disturbances. A slave centrifugal flywheel governor system is considered as an underactuated following-system which a control input is designed to follow a master centrifugal flywheel governor system. To tackle lumped disturbances and uncertainty parameters, a novel synchronization control law is developed by employing sliding mode control strategy and Nussbaum gain technique. Adaptation updating algorithms are derived in the sense of Lyapunov stability analysis such that the lumped disturbances can be suppressed and the adverse effect caused by uncertainty parameters can be compensated. In addition, the synchronization tracking-errors are proven to converge to a small neighborhood of the origin. Finally, simulation results demonstrate the effectiveness of the proposed control scheme. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Characterization of the pharmacokinetics of gasoline using PBPK modeling with a complex mixtures chemical lumping approach.

PubMed

Dennison, James E; Andersen, Melvin E; Yang, Raymond S H

2003-09-01

Gasoline consists of a few toxicologically significant components and a large number of other hydrocarbons in a complex mixture. By using an integrated, physiologically based pharmacokinetic (PBPK) modeling and lumping approach, we have developed a method for characterizing the pharmacokinetics (PKs) of gasoline in rats. The PBPK model tracks selected target components (benzene, toluene, ethylbenzene, o-xylene [BTEX], and n-hexane) and a lumped chemical group representing all nontarget components, with competitive metabolic inhibition between all target compounds and the lumped chemical. PK data was acquired by performing gas uptake PK studies with male F344 rats in a closed chamber. Chamber air samples were analyzed every 10-20 min by gas chromatography/flame ionization detection and all nontarget chemicals were co-integrated. A four-compartment PBPK model with metabolic interactions was constructed using the BTEX, n-hexane, and lumped chemical data. Target chemical kinetic parameters were refined by studies with either the single chemical alone or with all five chemicals together. o-Xylene, at high concentrations, decreased alveolar ventilation, consistent with respiratory irritation. A six-chemical interaction model with the lumped chemical group was used to estimate lumped chemical partitioning and metabolic parameters for a winter blend of gasoline with methyl t-butyl ether and a summer blend without any oxygenate. Computer simulation results from this model matched well with experimental data from single chemical, five-chemical mixture, and the two blends of gasoline. The PBPK model analysis indicated that metabolism of individual components was inhibited up to 27% during the 6-h gas uptake experiments of gasoline exposures.

Flexible hydrological modeling - Disaggregation from lumped catchment scale to higher spatial resolutions

NASA Astrophysics Data System (ADS)

Tran, Quoc Quan; Willems, Patrick; Pannemans, Bart; Blanckaert, Joris; Pereira, Fernando; Nossent, Jiri; Cauwenberghs, Kris; Vansteenkiste, Thomas

2015-04-01

Based on an international literature review on model structures of existing rainfall-runoff and hydrological models, a generalized model structure is proposed. It consists of different types of meteorological components, storage components, splitting components and routing components. They can be spatially organized in a lumped way, or on a grid, spatially interlinked by source-to-sink or grid-to-grid (cell-to-cell) routing. The grid size of the model can be chosen depending on the application. The user can select/change the spatial resolution depending on the needs and/or the evaluation of the accuracy of the model results, or use different spatial resolutions in parallel for different applications. Major research questions addressed during the study are: How can we assure consistent results of the model at any spatial detail? How can we avoid strong or sudden changes in model parameters and corresponding simulation results, when one moves from one level of spatial detail to another? How can we limit the problem of overparameterization/equifinality when we move from the lumped model to the spatially distributed model? The proposed approach is a step-wise one, where first the lumped conceptual model is calibrated using a systematic, data-based approach, followed by a disaggregation step where the lumped parameters are disaggregated based on spatial catchment characteristics (topography, land use, soil characteristics). In this way, disaggregation can be done down to any spatial scale, and consistently among scales. Only few additional calibration parameters are introduced to scale the absolute spatial differences in model parameters, but keeping the relative differences as obtained from the spatial catchment characteristics. After calibration of the spatial model, the accuracies of the lumped and spatial models were compared for peak, low and cumulative runoff total and sub-flows (at downstream and internal gauging stations). For the distributed models, additional validation on spatial results was done for the groundwater head values at observation wells. To ensure that the lumped model can produce results as accurate as the spatially distributed models or close regardless to the number of parameters and implemented physical processes, it was checked whether the structure of the lumped models had to be adjusted. The concept has been implemented in a PCRaster - Python platform and tested for two Belgian case studies (catchments of the rivers Dijle and Grote Nete). So far, use is made of existing model structures (NAM, PDM, VHM and HBV). Acknowledgement: These results were obtained within the scope of research activities for the Flemish Environment Agency (VMM) - division Operational Water Management on "Next Generation hydrological modeling", in cooperation with IMDC consultants, and for Flanders Hydraulics Research (Waterbouwkundig Laboratorium) on "Effect of climate change on the hydrological regime of navigable watercourses in Belgium".

Paul Drude's Prediction of Nonreciprocal Mutual Inductance for Tesla Transformers

PubMed Central

McGuyer, Bart

2014-01-01

Inductors, transmission lines, and Tesla transformers have been modeled with lumped-element equivalent circuits for over a century. In a well-known paper from 1904, Paul Drude predicts that the mutual inductance for an unloaded Tesla transformer should be nonreciprocal. This historical curiosity is mostly forgotten today, perhaps because it appears incorrect. However, Drude's prediction is shown to be correct for the conditions treated, demonstrating the importance of constraints in deriving equivalent circuits for distributed systems. The predicted nonreciprocity is not fundamental, but instead is an artifact of the misrepresentation of energy by an equivalent circuit. The application to modern equivalent circuits is discussed. PMID:25542040

Paul Drude's prediction of nonreciprocal mutual inductance for Tesla transformers.

PubMed

McGuyer, Bart

2014-01-01

Inductors, transmission lines, and Tesla transformers have been modeled with lumped-element equivalent circuits for over a century. In a well-known paper from 1904, Paul Drude predicts that the mutual inductance for an unloaded Tesla transformer should be nonreciprocal. This historical curiosity is mostly forgotten today, perhaps because it appears incorrect. However, Drude's prediction is shown to be correct for the conditions treated, demonstrating the importance of constraints in deriving equivalent circuits for distributed systems. The predicted nonreciprocity is not fundamental, but instead is an artifact of the misrepresentation of energy by an equivalent circuit. The application to modern equivalent circuits is discussed.

Multi-objective optimal design of magnetorheological engine mount based on an improved non-dominated sorting genetic algorithm

NASA Astrophysics Data System (ADS)

Zheng, Ling; Duan, Xuwei; Deng, Zhaoxue; Li, Yinong

2014-03-01

A novel flow-mode magneto-rheological (MR) engine mount integrated a diaphragm de-coupler and the spoiler plate is designed and developed to isolate engine and the transmission from the chassis in a wide frequency range and overcome the stiffness in high frequency. A lumped parameter model of the MR engine mount in single degree of freedom system is further developed based on bond graph method to predict the performance of the MR engine mount accurately. The optimization mathematical model is established to minimize the total of force transmissibility over several frequency ranges addressed. In this mathematical model, the lumped parameters are considered as design variables. The maximum of force transmissibility and the corresponding frequency in low frequency range as well as individual lumped parameter are limited as constraints. The multiple interval sensitivity analysis method is developed to select the optimized variables and improve the efficiency of optimization process. An improved non-dominated sorting genetic algorithm (NSGA-II) is used to solve the multi-objective optimization problem. The synthesized distance between the individual in Pareto set and the individual in possible set in engineering is defined and calculated. A set of real design parameters is thus obtained by the internal relationship between the optimal lumped parameters and practical design parameters for the MR engine mount. The program flowchart for the improved non-dominated sorting genetic algorithm (NSGA-II) is given. The obtained results demonstrate the effectiveness of the proposed optimization approach in minimizing the total of force transmissibility over several frequency ranges addressed.

A novel analytical description of periodic volume coil geometries in MRI

NASA Astrophysics Data System (ADS)

Koh, D.; Felder, J.; Shah, N. J.

2018-03-01

MRI volume coils can be represented by equivalent lumped element circuits and for a variety of these circuit configurations analytical design equations have been presented. The unification of several volume coil topologies results in a two-dimensional gridded equivalent lumped element circuit which compromises the birdcage resonator, its multiple endring derivative but also novel structures like the capacitive coupled ring resonator. The theory section analyzes a general two-dimensional circuit by noting that its current distribution can be decomposed into a longitudinal and an azimuthal dependency. This can be exploited to compare the current distribution with a transfer function of filter circuits along one direction. The resonances of the transfer function coincide with the resonance of the volume resonator and the simple analytical solution can be used as a design equation. The proposed framework is verified experimentally against a novel capacitive coupled ring structure which was derived from the general circuit formulation and is proven to exhibit a dominant homogeneous mode. In conclusion, a unified analytical framework is presented that allows determining the resonance frequency of any volume resonator that can be represented by a two dimensional meshed equivalent circuit.

Modeling Piezoelectric Stack Actuators for Control of Micromanipulation

NASA Technical Reports Server (NTRS)

Goldfarb, Michael; Celanovic, Nikola

1997-01-01

A nonlinear lumped-parameter model of a piezoelectric stack actuator has been developed to describe actuator behavior for purposes of control system analysis and design, and, in particular, for microrobotic applications requiring accurate position and/or force control. In formulating this model, the authors propose a generalized Maxwell resistive capacitor as a lumped-parameter causal representation of rate-independent hysteresis. Model formulation is validated by comparing results of numerical simulations to experimental data. Validation is followed by a discussion of model implications for purposes of actuator control.

Multi-band Monopole Antennas Loaded with Metamaterial TL

NASA Astrophysics Data System (ADS)

Song, Zhi-jie; Liang, Jian-gang

2015-05-01

A novel metamaterial transmission line (TL) by loading complementary single Archimedean spiral resonator pair (CSASRP) is investigated and used to design a set of multi-frequency monopole antennas. The particularity is that the CSASRP which features dual-shunt branches in the equivalent circuit model is directly etched in the signal strip. By smartly controlling the element parameters, three antennas are designed and one of them covering UMTS and Bluetooth bands is fabricated and measured. The antenna exhibits impedance matching better than -10 dB and normal monopolar radiation patterns at working bands of 1.9-2.22 and 2.38-2.5 GHz. Moreover, the loaded element also contributes to the radiation, which is the major advantage of this prescription over previous lumped-element loadings. The proposed antenna is also more compact over previous designs.

Assessment of hemodynamic load components affecting optimization of cardiac resynchronization therapy by lumped parameter mode.

PubMed

Xu, Ke; Butlin, Mark; Avolio, Alberto P

2012-01-01

Timing of biventricular pacing devices employed in cardiac resynchronization therapy (CRT) is a critical determinant of efficacy of the procedure. Optimization is done by maximizing function in terms of arterial pressure (BP) or cardiac output (CO). However, BP and CO are also determined by the hemodynamic load of the pulmonary and systemic vasculature. This study aims to use a lumped parameter circulatory model to assess the influence of the arterial load on the atrio-ventricular (AV) and inter-ventricular (VV) delay for optimal CRT performance.

Effect of ambient temperature on species lumping for total organic gases in gasoline exhaust emissions

NASA Astrophysics Data System (ADS)

Roy, Anirban; Choi, Yunsoo

2017-03-01

Volatile organic compound (VOCs) emissions from sources often need to be compressed or "lumped" into species classes for use in emissions inventories intended for air quality modeling. This needs to be done to ensure computational efficiency. The lumped profiles are usually reported for one value of ambient temperature. However, temperature-specific detailed profiles have been constructed in the recent past - the current study investigates how the lumping of species from those profiles into different atmospheric chemistry mechanisms is affected by temperature, considering three temperatures (-18 °C, -7 °C and 24 °C). The mechanisms considered differed on the assumptions used for lumping: CB05 (carbon bond type), SAPRC (ozone formation potential) and RACM2 (molecular surrogate and reactivity weighting). In this space, four sub-mechanisms for SAPRC were considered. Scaling factors were developed for each lumped model species and mechanism in terms of moles of lumped species per unit mass. Species which showed a direct one-to-one mapping (SAPRC/RACM2) reported scaling factors that were unchanged across mechanisms. However, CB05 showed different trends since one compound often is mapped onto multiple model species, out of which the paraffinic double bond (PAR) is predominant. Temperature-dependent parameterizations for emission factors pertaining to each lumped species class and mechanism were developed as part of the study. Here, the same kind of model species showed varying lumping parameters across the different mechanisms. These differences could be attributed to differing approaches in lumping. The scaling factors and temperature-dependent parameterizations could be used to update emissions inventories such as MOVES or SMOKE for use in chemical transport modeling.

An approach for including the stiffness and damping of elastohydrodynamic point contacts in deep groove ball bearing equilibrium models

NASA Astrophysics Data System (ADS)

Nonato, Fábio; Cavalca, Katia L.

2014-12-01

This work presents a methodology for including the Elastohydrodynamic (EHD) film effects to a lateral vibration model of a deep groove ball bearing by using a novel approximation for the EHD contacts by a set of equivalent nonlinear spring and viscous damper. The fitting of the equivalent contact model used the results of a transient multi-level finite difference EHD algorithm to adjust the dynamic parameters. The comparison between the approximated model and the finite difference simulated results showed a suitable representation of the stationary and dynamic contact behaviors. The linear damping hypothesis could be shown as a rough representation of the actual hysteretic behavior of the EHD contact. Nevertheless, the overall accuracy of the model was not impaired by the use of such approximation. Further on, the inclusion of the equivalent EHD contact model is equated for both the restoring and the dissipative components of the bearing's lateral dynamics. The derived model was used to investigate the effects of the rolling element bearing lubrication on the vibration response of a rotor's lumped parameter model. The fluid film stiffening effect, previously only observable by experimentation, could be quantified using the proposed model, as well as the portion of the bearing damping provided by the EHD fluid film. Results from a laboratory rotor-bearing test rig were used to indirectly validate the proposed contact approximation. A finite element model of the rotor accounting for the lubricated bearing formulation adequately portrayed the frequency content of the bearing orbits observed on the test rig.

A new lumped-parameter model for flow in unsaturated dual-porosity media

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

Zimmerman, Robert W.; Hadgu, Teklu; Bodvarsson, Gudmundur S.

A new lumped-parameter approach to simulating unsaturated flow processes in dual-porosity media such as fractured rocks or aggregated soils is presented. Fluid flow between the fracture network and the matrix blocks is described by a non-linear equation that relates the imbibition rate to the local difference in liquid-phase pressure between the fractures and the matrix blocks. Unlike a Warren-Root-type equation, this equation is accurate in both the early and late time regimes. The fracture/matrix interflow equation has been incorporated into an existing unsaturated flow simulator, to serve as a source/sink term for fracture gridblocks. Flow processes are then simulated usingmore » only fracture gridblocks in the computational grid. This new lumped-parameter approach has been tested on two problems involving transient flow in fractured/porous media, and compared with simulations performed using explicit discretization of the matrix blocks. The new procedure seems to accurately simulate flow processes in unsaturated fractured rocks, and typically requires an order of magnitude less computational time than do simulations using fully-discretized matrix blocks. [References: 37]« less

Application of Biologically Based Lumping To Investigate the Toxicokinetic Interactions of a Complex Gasoline Mixture.

PubMed

Jasper, Micah N; Martin, Sheppard A; Oshiro, Wendy M; Ford, Jermaine; Bushnell, Philip J; El-Masri, Hisham

2016-03-15

People are often exposed to complex mixtures of environmental chemicals such as gasoline, tobacco smoke, water contaminants, or food additives. We developed an approach that applies chemical lumping methods to complex mixtures, in this case gasoline, based on biologically relevant parameters used in physiologically based pharmacokinetic (PBPK) modeling. Inhalation exposures were performed with rats to evaluate the performance of our PBPK model and chemical lumping method. There were 109 chemicals identified and quantified in the vapor in the chamber. The time-course toxicokinetic profiles of 10 target chemicals were also determined from blood samples collected during and following the in vivo experiments. A general PBPK model was used to compare the experimental data to the simulated values of blood concentration for 10 target chemicals with various numbers of lumps, iteratively increasing from 0 to 99. Large reductions in simulation error were gained by incorporating enzymatic chemical interactions, in comparison to simulating the individual chemicals separately. The error was further reduced by lumping the 99 nontarget chemicals. The same biologically based lumping approach can be used to simplify any complex mixture with tens, hundreds, or thousands of constituents.

Patient-specific parameter estimation in single-ventricle lumped circulation models under uncertainty

PubMed Central

Schiavazzi, Daniele E.; Baretta, Alessia; Pennati, Giancarlo; Hsia, Tain-Yen; Marsden, Alison L.

2017-01-01

Summary Computational models of cardiovascular physiology can inform clinical decision-making, providing a physically consistent framework to assess vascular pressures and flow distributions, and aiding in treatment planning. In particular, lumped parameter network (LPN) models that make an analogy to electrical circuits offer a fast and surprisingly realistic method to reproduce the circulatory physiology. The complexity of LPN models can vary significantly to account, for example, for cardiac and valve function, respiration, autoregulation, and time-dependent hemodynamics. More complex models provide insight into detailed physiological mechanisms, but their utility is maximized if one can quickly identify patient specific parameters. The clinical utility of LPN models with many parameters will be greatly enhanced by automated parameter identification, particularly if parameter tuning can match non-invasively obtained clinical data. We present a framework for automated tuning of 0D lumped model parameters to match clinical data. We demonstrate the utility of this framework through application to single ventricle pediatric patients with Norwood physiology. Through a combination of local identifiability, Bayesian estimation and maximum a posteriori simplex optimization, we show the ability to automatically determine physiologically consistent point estimates of the parameters and to quantify uncertainty induced by errors and assumptions in the collected clinical data. We show that multi-level estimation, that is, updating the parameter prior information through sub-model analysis, can lead to a significant reduction in the parameter marginal posterior variance. We first consider virtual patient conditions, with clinical targets generated through model solutions, and second application to a cohort of four single-ventricle patients with Norwood physiology. PMID:27155892

A physics-based model of the electrical impedance of ionic polymer metal composites

NASA Astrophysics Data System (ADS)

Cha, Youngsu; Aureli, Matteo; Porfiri, Maurizio

2012-06-01

In this paper, we analyze the chemoelectrical behavior of ionic polymer metal composites (IPMCs) in the small voltage range with a novel hypothesis on the charge dynamics in proximity of the electrodes. In particular, we homogenize the microscopic properties of the interfacial region through a so-called composite layer which extends between the polymer membrane and the metal electrode. This layer accounts for the dissimilar properties of its constituents by describing the charge distribution via two species of charge carriers, that is, electrons and mobile counterions. We model the charge dynamics in the IPMC by adapting the multiphysics formulation based on the Poisson-Nernst-Planck (PNP) framework, which is enriched through an additional term to capture the electron transport in the composite layer. Under the hypothesis of small voltage input, we use the linearized PNP model to derive an equivalent IPMC circuit model with lumped elements. The equivalent model comprises a resistor connected in series with the parallel of a capacitor and a Warburg impedance element. These elements idealize the phenomena of charge build up in the double layer region and the faradaic impedance related to mass transfer, respectively. We validate the equivalent model through measurements on in-house fabricated samples addressing both IPMC step response and impedance, while assessing the influence of repeated plating cycles on the electrical properties of IPMCs. Experimental results are compared with theoretical findings to identify the equivalent circuit parameters. Findings from this study are compared with alternative impedance models proposed in the literature.

A passive terahertz video camera based on lumped element kinetic inductance detectors

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

Rowe, Sam, E-mail: sam.rowe@astro.cf.ac.uk; Pascale, Enzo; Doyle, Simon

We have developed a passive 350 GHz (850 μm) video-camera to demonstrate lumped element kinetic inductance detectors (LEKIDs)—designed originally for far-infrared astronomy—as an option for general purpose terrestrial terahertz imaging applications. The camera currently operates at a quasi-video frame rate of 2 Hz with a noise equivalent temperature difference per frame of ∼0.1 K, which is close to the background limit. The 152 element superconducting LEKID array is fabricated from a simple 40 nm aluminum film on a silicon dielectric substrate and is read out through a single microwave feedline with a cryogenic low noise amplifier and room temperature frequencymore » domain multiplexing electronics.« less

Nonlinear dynamics of planetary gears using analytical and finite element models

NASA Astrophysics Data System (ADS)

Ambarisha, Vijaya Kumar; Parker, Robert G.

2007-05-01

Vibration-induced gear noise and dynamic loads remain key concerns in many transmission applications that use planetary gears. Tooth separations at large vibrations introduce nonlinearity in geared systems. The present work examines the complex, nonlinear dynamic behavior of spur planetary gears using two models: (i) a lumped-parameter model, and (ii) a finite element model. The two-dimensional (2D) lumped-parameter model represents the gears as lumped inertias, the gear meshes as nonlinear springs with tooth contact loss and periodically varying stiffness due to changing tooth contact conditions, and the supports as linear springs. The 2D finite element model is developed from a unique finite element-contact analysis solver specialized for gear dynamics. Mesh stiffness variation excitation, corner contact, and gear tooth contact loss are all intrinsically considered in the finite element analysis. The dynamics of planetary gears show a rich spectrum of nonlinear phenomena. Nonlinear jumps, chaotic motions, and period-doubling bifurcations occur when the mesh frequency or any of its higher harmonics are near a natural frequency of the system. Responses from the dynamic analysis using analytical and finite element models are successfully compared qualitatively and quantitatively. These comparisons validate the effectiveness of the lumped-parameter model to simulate the dynamics of planetary gears. Mesh phasing rules to suppress rotational and translational vibrations in planetary gears are valid even when nonlinearity from tooth contact loss occurs. These mesh phasing rules, however, are not valid in the chaotic and period-doubling regions.

Low-volume aluminum and aluminum / titanium nitride bilayer lumped-element kinetic inductance detectors for far-infrared astronomy

NASA Astrophysics Data System (ADS)

Glenn, Jason; Fyhrie, Adalyn; Wheeler, Jordan; Day, Peter K.; Eom, Byeong H.; Leduc, Henry G.

2016-07-01

We present the design and characterization of low-volume, lumped-element aluminum kinetic inductance de- tectors for sensitive far-infrared astronomy observations. The lumped-element kinetic inductance detectors are comprised of meandered inductors that serve as radiation absorbers in parallel with interdigitated capacitors, forming high quality factor resonators. Low inductor volumes lead to low noise equivalent powers by raising quasiparticles densities, and hence responsivities, with respect to larger volumes. Low volumes are achieved with thin (20 nm), narrow (150 nm) inductors. The interdigitated capacitor architecture is designed to mitigate two-level system noise by lowering electric fields in the silicon substrate. Resonance frequencies are in the range of 190 to 500 MHz, with measured internal quality factors in excess of 1 x 105. In a prior incarnation, a titanium nitride layer on top of the aluminum served as a protective layer, but complicated the superconducting proper- ties. These results were reported previously. In the current incarnation, the aluminum layer is left bare with no titanium nitride over-layer. The results for these bare aluminum devices include a yield of 88%, frequency responsivity of 109 W-1, and noise equivalent power of 1 x 10-17 W Hz-1/2 for a 350μm array. There is no evidence for 1=f noise down to at least 200 mHz. The sensitivity is currently limited by white noise, very likely from stray light in the testbed; for this detector design, sensitivities limited by generation-recombination noise in a lower-background environment should be several orders of magnitude lower.

lumpR 2.0.0: an R package facilitating landscape discretisation for hillslope-based hydrological models

NASA Astrophysics Data System (ADS)

Pilz, Tobias; Francke, Till; Bronstert, Axel

2017-08-01

The characteristics of a landscape pose essential factors for hydrological processes. Therefore, an adequate representation of the landscape of a catchment in hydrological models is vital. However, many of such models exist differing, amongst others, in spatial concept and discretisation. The latter constitutes an essential pre-processing step, for which many different algorithms along with numerous software implementations exist. In that context, existing solutions are often model specific, commercial, or depend on commercial back-end software, and allow only a limited or no workflow automation at all. Consequently, a new package for the scientific software and scripting environment R, called lumpR, was developed. lumpR employs an algorithm for hillslope-based landscape discretisation directed to large-scale application via a hierarchical multi-scale approach. The package addresses existing limitations as it is free and open source, easily extendible to other hydrological models, and the workflow can be fully automated. Moreover, it is user-friendly as the direct coupling to a GIS allows for immediate visual inspection and manual adjustment. Sufficient control is furthermore retained via parameter specification and the option to include expert knowledge. Conversely, completely automatic operation also allows for extensive analysis of aspects related to landscape discretisation. In a case study, the application of the package is presented. A sensitivity analysis of the most important discretisation parameters demonstrates its efficient workflow automation. Considering multiple streamflow metrics, the employed model proved reasonably robust to the discretisation parameters. However, parameters determining the sizes of subbasins and hillslopes proved to be more important than the others, including the number of representative hillslopes, the number of attributes employed for the lumping algorithm, and the number of sub-discretisations of the representative hillslopes.

On 4-degree-of-freedom biodynamic models of seated occupants: Lumped-parameter modeling

NASA Astrophysics Data System (ADS)

Bai, Xian-Xu; Xu, Shi-Xu; Cheng, Wei; Qian, Li-Jun

2017-08-01

It is useful to develop an effective biodynamic model of seated human occupants to help understand the human vibration exposure to transportation vehicle vibrations and to help design and improve the anti-vibration devices and/or test dummies. This study proposed and demonstrated a methodology for systematically identifying the best configuration or structure of a 4-degree-of-freedom (4DOF) human vibration model and for its parameter identification. First, an equivalent simplification expression for the models was made. Second, all of the possible 23 structural configurations of the models were identified. Third, each of them was calibrated using the frequency response functions recommended in a biodynamic standard. An improved version of non-dominated sorting genetic algorithm (NSGA-II) based on Pareto optimization principle was used to determine the model parameters. Finally, a model evaluation criterion proposed in this study was used to assess the models and to identify the best one, which was based on both the goodness of curve fits and comprehensive goodness of the fits. The identified top configurations were better than those reported in the literature. This methodology may also be extended and used to develop the models with other DOFs.

A Pair of Resonance Stripe Solitons and Lump Solutions to a Reduced (3+1)-Dimensional Nonlinear Evolution Equation

NASA Astrophysics Data System (ADS)

Chen, Mei-Dan; Li, Xian; Wang, Yao; Li, Biao

2017-06-01

With symbolic computation, some lump solutions are presented to a (3+1)-dimensional nonlinear evolution equation by searching the positive quadratic function from the Hirota bilinear form of equation. The quadratic function contains six free parameters, four of which satisfy two determinant conditions guaranteeing analyticity and rational localization of the solutions, while the others are free. Then, by combining positive quadratic function with exponential function, the interaction solutions between lump solutions and the stripe solitons are presented on the basis of some conditions. Furthermore, we extend this method to obtain more general solutions by combining of positive quadratic function and hyperbolic cosine function. Thus the interaction solutions between lump solutions and a pair of resonance stripe solitons are derived and asymptotic property of the interaction solutions are analyzed under some specific conditions. Finally, the dynamic properties of these solutions are shown in figures by choosing the values of the parameters. Supported by National Natural Science Foundation of China under Grant Nos. 11271211, 11275072, and 11435005, Ningbo Natural Science Foundation under Grant No. 2015A610159 and the Opening Project of Zhejiang Provincial Top Key Discipline of Physics Sciences in Ningbo University under Grant No. xkzw11502 and K.C. Wong Magna Fund in Ningbo University

RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.11)

NASA Astrophysics Data System (ADS)

Long, A. J.

2014-09-01

The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, springflow, groundwater level, solute transport, or cave drip for a measurement point in response to a system input of precipitation, recharge, or solute injection. The RRAWFLOW open-source code is written in the R language and is included in the Supplement to this article along with an example model of springflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution; i.e., the unit hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Other options include the use of user-defined IRFs and different methods to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications. RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

Solving transient acoustic boundary value problems with equivalent sources using a lumped parameter approach.

PubMed

Fahnline, John B

2016-12-01

An equivalent source method is developed for solving transient acoustic boundary value problems. The method assumes the boundary surface is discretized in terms of triangular or quadrilateral elements and that the solution is represented using the acoustic fields of discrete sources placed at the element centers. Also, the boundary condition is assumed to be specified for the normal component of the surface velocity as a function of time, and the source amplitudes are determined to match the known elemental volume velocity vector at a series of discrete time steps. Equations are given for marching-on-in-time schemes to solve for the source amplitudes at each time step for simple, dipole, and tripole source formulations. Several example problems are solved to illustrate the results and to validate the formulations, including problems with closed boundary surfaces where long-time numerical instabilities typically occur. A simple relationship between the simple and dipole source amplitudes in the tripole source formulation is derived so that the source radiates primarily in the direction of the outward surface normal. The tripole source formulation is shown to eliminate interior acoustic resonances and long-time numerical instabilities.

Dark lump excitations in superfluid Fermi gases

NASA Astrophysics Data System (ADS)

Xu, Yan-Xia; Duan, Wen-Shan

2012-11-01

We study the linear and nonlinear properties of two-dimensional matter-wave pulses in disk-shaped superfluid Fermi gases. A Kadomtsev—Petviashvili I (KPI) solitary wave has been realized for superfluid Fermi gases in the limited cases of Bardeen—Cooper—Schrieffer (BCS) regime, Bose—Einstein condensate (BEC) regime, and unitarity regime. One-lump solution as well as one-line soliton solutions for the KPI equation are obtained, and two-line soliton solutions with the same amplitude are also studied in the limited cases. The dependence of the lump propagating velocity and the sound speed of two-dimensional superfluid Fermi gases on the interaction parameter are investigated for the limited cases of BEC and unitarity.

Comparison the Results of Numerical Simulation And Experimental Results for Amirkabir Plasma Focus Facility

NASA Astrophysics Data System (ADS)

Goudarzi, Shervin; Amrollahi, R.; Niknam Sharak, M.

2014-06-01

In this paper the results of the numerical simulation for Amirkabir Mather-type Plasma Focus Facility (16 kV, 36μF and 115 nH) in several experiments with Argon as working gas at different working conditions (different discharge voltages and gas pressures) have been presented and compared with the experimental results. Two different models have been used for simulation: five-phase model of Lee and lumped parameter model of Gonzalez. It is seen that the results (optimum pressures and current signals) of the Lee model at different working conditions show better agreement than lumped parameter model with experimental values.

Two methods for modeling vibrations of planetary gearboxes including faults: Comparison and validation

NASA Astrophysics Data System (ADS)

Parra, J.; Vicuña, Cristián Molina

2017-08-01

Planetary gearboxes are important components of many industrial applications. Vibration analysis can increase their lifetime and prevent expensive repair and safety concerns. However, an effective analysis is only possible if the vibration features of planetary gearboxes are properly understood. In this paper, models are used to study the frequency content of planetary gearbox vibrations under non-fault and different fault conditions. Two different models are considered: phenomenological model, which is an analytical-mathematical formulation based on observation, and lumped-parameter model, which is based on the solution of the equations of motion of the system. Results of both models are not directly comparable, because the phenomenological model provides the vibration on a fixed radial direction, such as the measurements of the vibration sensor mounted on the outer part of the ring gear. On the other hand, the lumped-parameter model provides the vibrations on the basis of a rotating reference frame fixed to the carrier. To overcome this situation, a function to decompose the lumped-parameter model solutions to a fixed reference frame is presented. Finally, comparisons of results from both model perspectives and experimental measurements are presented.

Optimization of Quenching Parameters for the Reduction of Titaniferous Magnetite Ore by Lean Grade Coal Using the Taguchi Method and Its Isothermal Kinetic Study

NASA Astrophysics Data System (ADS)

Sarkar, Bitan Kumar; Kumar, Nikhil; Dey, Rajib; Das, Gopes Chandra

2018-06-01

In the present study, a unique method is adopted to achieve higher reducibility of titaniferous magnetite lump ore (TMO). In this method, TMO is initially heated followed by water quenching. The quenching process generates cracks due to thermal shock in the dense TMO lumps, which, in turn, increases the extent of reduction (EOR) using the lean grade coal as a reductant. The optimum combination of parameters found by using Taguchi's L27 orthogonal array (OA) (five factors, three levels) is - 8 + 4 mm of particle size (PS1), 1423 K of quenching temperature (Qtemp2), 15 minutes of quenching time (Qtime3), 3 times the number of quenching {(No. of Q)3}, and 120 minutes of reduction time (Rtime3) at fixed reduction temperature of 1473 K. At optimized levels of the parameters, 92.39 pct reduction is achieved. Isothermal reduction kinetics of the quenched TMO lumps at the optimized condition reveals mixed controlled mechanisms [initially contracting geometry (CG3) followed by diffusion (D3)]. Activation energies calculated are 69.895 KJ/mole for CG3 and 39.084 KJ/mole for D3.

College Savings Plans: Second Generation Progress and Problems.

ERIC Educational Resources Information Center

Olivas, Michael A.

College savings plans, which operate in 20 states, work on a simple premise: parents or grandparents place a lump sum in a contract or make monthly payments that guarantees the money will be sufficient for an equivalent of tuition and fees in a set period of time in the future. The state can guarantee the return by virtue of pooled assets. States…

A new method for analyzing the refill process and fabrication of a piezoelectric inkjet printing head for LCD color filter manufacturing

NASA Astrophysics Data System (ADS)

Moon, Kang Seok; Choi, Jung Hoon; Choi, Dong-June; Kim, Sun Ho; Hyo Ha, Man; Nam, Hyo-Jin; Kim, Min Soo

2008-12-01

This paper presents a method for analyzing the refill process of a piezoelectric inkjet printing head with a high firing frequency for color filter manufacturing. Theoretical and experimental studies on the equivalent length (Leq) versus jetting characteristics were performed. The new model has shown quantitatively the same result compared with a commercialized simulation code. Also it is identified that the refill time increases with the equivalent liquid length (Leq) because the viscous force increases. The inkjet printing head has been designed with a lumped model analysis and fabricated with a silicon wafer (1 0 0) by a MEMS process. To investigate how the equivalent length (Leq) influences the firing frequency, an experiment was conducted using a stroboscope. In the case of colorant ink, it is possible to eject an ink droplet up to 5 kHz with a 40 pl drop volume. On the other hand, the firing frequency calculated with the new model is about 3 kHz under the condition of the equivalent liquid length (Leq), 250 µm. The difference between the new model and experiment may be a result of a mismatch of initial meniscus position due to the meniscus oscillation. Experimentally the meniscus oscillation is observed through an optical measurement with a visualization apparatus and a transparent nozzle. Hence the efficiency of the new model may be enhanced in a high viscosity range. The methods for increasing the firing frequency are to reduce the equivalent length (Leq) and to modify the ink property. Because the former tends to decrease a viscous loss and the latter tends to increase a viscous damping, two parameters should be combined adequately within an allowable drop volume.

A new 3D finite element model of the IEC 60318-1 artificial ear: II. Experimental and numerical validation

NASA Astrophysics Data System (ADS)

Bravo, Agustín; Barham, Richard; Ruiz, Mariano; López, Juan Manuel; De Arcas, Guillermo; Alonso, Jesus

2012-12-01

In part I, the feasibility of using three-dimensional (3D) finite elements (FEs) to model the acoustic behaviour of the IEC 60318-1 artificial ear was studied and the numerical approach compared with classical lumped elements modelling. It was shown that by using a more complex acoustic model that took account of thermo-viscous effects, geometric shapes and dimensions, it was possible to develop a realistic model. This model then had clear advantages in comparison with the models based on equivalent circuits using lumped parameters. In fact results from FE modelling produce a better understanding about the physical phenomena produced inside ear simulator couplers, facilitating spatial and temporal visualization of the sound fields produced. The objective of this study (part II) is to extend the investigation by validating the numerical calculations against measurements on an ear simulator conforming to IEC 60318-1. For this purpose, an appropriate commercially available device is taken and a complete 3D FE model developed for it. The numerical model is based on key dimensional data obtained with a non-destructive x-ray inspection technique. Measurements of the acoustic transfer impedance have been carried out on the same device at a national measurement institute using the method embodied in IEC 60318-1. Having accounted for the actual device dimensions, the thermo-viscous effects inside narrow slots and holes and environmental conditions, the results of the numerical modelling were found to be in good agreement with the measured values.

SUITABILITY OF USING IN VITRO AND COMPUTATIONALLY ESTIMATED PARAMETERS IN SIMPLIFIED PHARMACOKINETIC MODELS

EPA Science Inventory

A challenge in PBPK model development is estimating the parameters for absorption, distribution, metabolism, and excretion of the parent compound and metabolites of interest. One approach to reduce the number of parameters has been to simplify pharmacokinetic models by lumping p...

RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.15)

USGS Publications Warehouse

Long, Andrew J.

2015-01-01

The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, spring flow, groundwater level, or solute transport for a measurement point in response to a system input of precipitation, recharge, or solute injection. I introduce the first version of RRAWFLOW available for download and public use and describe additional options. The open-source code is written in the R language and is available at http://sd.water.usgs.gov/projects/RRAWFLOW/RRAWFLOW.html along with an example model of streamflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution, i.e., the unit-hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Several options are included to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications (e.g., estimating missing periods in a hydrologic record). RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

Behavioral Implications of Piezoelectric Stack Actuators for Control of Micromanipulation

NASA Technical Reports Server (NTRS)

Goldfarb, Michael; Celanovic, Nikola

1996-01-01

A lumped-parameter model of a piezoelectric stack actuator has been developed to describe actuator behavior for purposes of control system analysis and design, and in particular for microrobotic applications requiring accurate position and/or force control. In addition to describing the input-output dynamic behavior, the proposed model explains aspects of non-intuitive behavioral phenomena evinced by piezoelectric actuators, such as the input-output rate-independent hysteresis and the change in mechanical stiffness that results from altering electrical load. The authors incorporate a generalized Maxwell resistive capacitor as a lumped-parameter causal representation of rate-independent hysteresis. Model formulation is validated by comparing results of numerical simulations to experimental data.

Stochastic lumping analysis for linear kinetics and its application to the fluctuation relations between hierarchical kinetic networks.

PubMed

Deng, De-Ming; Chang, Cheng-Hung

2015-05-14

Conventional studies of biomolecular behaviors rely largely on the construction of kinetic schemes. Since the selection of these networks is not unique, a concern is raised whether and under which conditions hierarchical schemes can reveal the same experimentally measured fluctuating behaviors and unique fluctuation related physical properties. To clarify these questions, we introduce stochasticity into the traditional lumping analysis, generalize it from rate equations to chemical master equations and stochastic differential equations, and extract the fluctuation relations between kinetically and thermodynamically equivalent networks under intrinsic and extrinsic noises. The results provide a theoretical basis for the legitimate use of low-dimensional models in the studies of macromolecular fluctuations and, more generally, for exploring stochastic features in different levels of contracted networks in chemical and biological kinetic systems.

Improved test methods for determining lightning-induced voltages in aircraft

NASA Technical Reports Server (NTRS)

Crouch, K. E.; Plumer, J. A.

1980-01-01

A lumped parameter transmission line with a surge impedance matching that of the aircraft and its return lines was evaluated as a replacement for earlier current generators. Various test circuit parameters were evaluated using a 1/10 scale relative geometric model. Induced voltage response was evaluated by taking measurements on the NASA-Dryden Digital Fly by Wire F-8 aircraft. Return conductor arrangements as well as other circuit changes were also evaluated, with all induced voltage measurements being made on the same circuit for comparison purposes. The lumped parameter transmission line generates a concave front current wave with the peak di/dt near the peak of the current wave which is more representative of lightning. However, the induced voltage measurements when scaled by appropriate scale factors (peak current or di/dt) resulting from both techniques yield comparable results.

Implementation of interconnect simulation tools in spice

NASA Technical Reports Server (NTRS)

Satsangi, H.; Schutt-Aine, J. E.

1993-01-01

Accurate computer simulation of high speed digital computer circuits and communication circuits requires a multimode approach to simulate both the devices and the interconnects between devices. Classical circuit analysis algorithms (lumped parameter) are needed for circuit devices and the network formed by the interconnected devices. The interconnects, however, have to be modeled as transmission lines which incorporate electromagnetic field analysis. An approach to writing a multimode simulator is to take an existing software package which performs either lumped parameter analysis or field analysis and add the missing type of analysis routines to the package. In this work a traditionally lumped parameter simulator, SPICE, is modified so that it will perform lossy transmission line analysis using a different model approach. Modifying SPICE3E2 or any other large software package is not a trivial task. An understanding of the programming conventions used, simulation software, and simulation algorithms is required. This thesis was written to clarify the procedure for installing a device into SPICE3E2. The installation of three devices is documented and the installations of the first two provide a foundation for installation of the lossy line which is the third device. The details of discussions are specific to SPICE, but the concepts will be helpful when performing installations into other circuit analysis packages.

Design and Experimental Evaluation of a Robust Position Controller for an Electrohydrostatic Actuator Using Adaptive Antiwindup Sliding Mode Scheme

PubMed Central

Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

2013-01-01

A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. PMID:23983640

Nonlinear dynamics of a circular piezoelectric plate for vibratory energy harvesting

NASA Astrophysics Data System (ADS)

Yuan, Tian-Chen; Yang, Jian; Chen, Li-Qun

2018-06-01

Nonlinear behaviors are investigated for a vibration-based energy harvester. The harvester consists of a circular composite plate with the clamped boundary, a proof mass and two steel rings. The lumped parameter model of the harvester is established and the parameters are identified from the experiment. The measured nonlinear behaviors can be approximately described by the lumped model. Both the experimental and the numerical results demonstrate that the circular plate harvester has soft characteristics under low excitation and both hard characteristics and soft characteristics under high excitation. The experimental results show that the output voltage can achieve over 35 V (about 50 mW) and more than 14 Hz of bandwidth with 25 kΩ load resistance.

Application of Biologically-Based Lumping To Investigate the ...

EPA Pesticide Factsheets

People are often exposed to complex mixtures of environmental chemicals such as gasoline, tobacco smoke, water contaminants, or food additives. However, investigators have often considered complex mixtures as one lumped entity. Valuable information can be obtained from these experiments, though this simplification provides little insight into the impact of a mixture's chemical composition on toxicologically-relevant metabolic interactions that may occur among its constituents. We developed an approach that applies chemical lumping methods to complex mixtures, in this case gasoline, based on biologically relevant parameters used in physiologically-based pharmacokinetic (PBPK) modeling. Inhalation exposures were performed with rats to evaluate performance of our PBPK model. There were 109 chemicals identified and quantified in the vapor in the chamber. The time-course kinetic profiles of 10 target chemicals were also determined from blood samples collected during and following the in vivo experiments. A general PBPK model was used to compare the experimental data to the simulated values of blood concentration for the 10 target chemicals with various numbers of lumps, iteratively increasing from 0 to 99. Large reductions in simulation error were gained by incorporating enzymatic chemical interactions, in comparison to simulating the individual chemicals separately. The error was further reduced by lumping the 99 non-target chemicals. Application of this biologic

Mathematical circulatory system model

NASA Technical Reports Server (NTRS)

Lakin, William D. (Inventor); Stevens, Scott A. (Inventor)

2010-01-01

A system and method of modeling a circulatory system including a regulatory mechanism parameter. In one embodiment, a regulatory mechanism parameter in a lumped parameter model is represented as a logistic function. In another embodiment, the circulatory system model includes a compliant vessel, the model having a parameter representing a change in pressure due to contraction of smooth muscles of a wall of the vessel.

RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.15)

NASA Astrophysics Data System (ADS)

Long, A. J.

2015-03-01

The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, spring flow, groundwater level, or solute transport for a measurement point in response to a system input of precipitation, recharge, or solute injection. I introduce the first version of RRAWFLOW available for download and public use and describe additional options. The open-source code is written in the R language and is available at http://sd.water.usgs.gov/projects/RRAWFLOW/RRAWFLOW.html along with an example model of streamflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution, i.e., the unit-hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Several options are included to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications (e.g., estimating missing periods in a hydrologic record). RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

Fault detection in heavy duty wheels by advanced vibration processing techniques and lumped parameter modeling

NASA Astrophysics Data System (ADS)

Malago`, M.; Mucchi, E.; Dalpiaz, G.

2016-03-01

Heavy duty wheels are used in applications such as automatic vehicles and are mainly composed of a polyurethane tread glued to a cast iron hub. In the manufacturing process, the adhesive application between tread and hub is a critical assembly phase, since it is completely made by an operator and a contamination of the bond area may happen. Furthermore, the presence of rust on the hub surface can contribute to worsen the adherence interface, reducing the operating life. In this scenario, a quality control procedure for fault detection to be used at the end of the manufacturing process has been developed. This procedure is based on vibration processing techniques and takes advantages of the results of a lumped parameter model. Indicators based on cyclostationarity can be considered as key parameters to be adopted in a monitoring test station at the end of the production line due to their not deterministic characteristics.

A new analytical method for estimating lumped parameter constants of linear viscoelastic models from strain rate tests

NASA Astrophysics Data System (ADS)

Mattei, G.; Ahluwalia, A.

2018-04-01

We introduce a new function, the apparent elastic modulus strain-rate spectrum, E_{app} ( \\dot{ɛ} ), for the derivation of lumped parameter constants for Generalized Maxwell (GM) linear viscoelastic models from stress-strain data obtained at various compressive strain rates ( \\dot{ɛ}). The E_{app} ( \\dot{ɛ} ) function was derived using the tangent modulus function obtained from the GM model stress-strain response to a constant \\dot{ɛ} input. Material viscoelastic parameters can be rapidly derived by fitting experimental E_{app} data obtained at different strain rates to the E_{app} ( \\dot{ɛ} ) function. This single-curve fitting returns similar viscoelastic constants as the original epsilon dot method based on a multi-curve global fitting procedure with shared parameters. Its low computational cost permits quick and robust identification of viscoelastic constants even when a large number of strain rates or replicates per strain rate are considered. This method is particularly suited for the analysis of bulk compression and nano-indentation data of soft (bio)materials.

A wave model for rigid-frame porous materials using lumped parameter concepts

NASA Astrophysics Data System (ADS)

Rossetti, S.; Gardonio, P.; Brennan, M. J.

2005-08-01

The work presented in this paper concerns the behaviour of porous media when exposed to a normal incidence sound field. A propagating wave model based on lumped parameter concepts of acoustic mass, stiffness and damping is used to investigate the absorption phenomena due to the wave propagation in the layer(s) and interference effects due to the wave reflection-transmission at the interfaces of the layer(s). Results from the theoretical model have been validated by measurements on samples of consolidated rubber granulate material. Two typical installations where a layer of porous material is placed next to a rigid wall, and where it is placed at a distance from a rigid wall are used as reference cases. The geometrical and physical properties of porous materials can be described by such parameters as the non-dimensional shape factor and the porosity. The propagating model introduced is used to investigate the effect of these two parameters on acoustic absorption and thus relate the physical properties to the acoustic behaviour.

Hydrodynamic flow in the vicinity of a nanopore induced by an applied voltage

PubMed Central

Mao, Mao; Ghosal, Sandip; Hu, Guohui

2013-01-01

Continuum simulation is employed to study ion transport and fluid flow through a nanopore in a solid-state membrane under an applied potential drop. Results show the existence of concentration polarization layers on the surfaces of the membrane. The nonuniformity of the ionic distribution gives rise to an electric pressure that drives vortical motion in the fluid. There is also a net hydrodynamic flow through the nanopore due to an asymmetry induced by the membrane surface charge. The qualitative behavior is similar to that observed in a previous study using molecular dynamic simulations. The current–voltage characteristics show some nonlinear features but are not greatly affected by the hydrodynamic flow in the parameter regime studied. In the limit of thin Debye layers, the electric resistance of the system can be characterized using an equivalent circuit with lumped parameters. Generation of vorticity can be understood qualitatively from elementary considerations of the Maxwell stresses. However, the flow strength is a strongly nonlinear function of the applied field. Combination of electrophoretic and hydrodynamic effects can lead to ion selectivity in terms of valences and this could have some practical applications in separations. PMID:23689946

Application of a rat hindlimb model: a prediction of force spaces reachable through stimulation of nerve fascicles.

PubMed

Johnson, Will L; Jindrich, Devin L; Zhong, Hui; Roy, Roland R; Edgerton, V Reggie

2011-12-01

A device to generate standing or locomotion through chronically placed electrodes has not been fully developed due in part to limitations of clinical experimentation and the high number of muscle activation inputs of the leg. We investigated the feasibility of functional electrical stimulation paradigms that minimize the input dimensions for controlling the limbs by stimulating at nerve fascicles, utilizing a model of the rat hindlimb, which combined previously collected morphological data with muscle physiological parameters presented herein. As validation of the model, we investigated the suitability of a lumped-parameter model for the prediction of muscle activation during dynamic tasks. Using the validated model, we found that the space of forces producible through activation of muscle groups sharing common nerve fascicles was nonlinearly dependent on the number of discrete muscle groups that could be individually activated (equivalently, the neuroanatomical level of activation). Seven commonly innervated muscle groups were sufficient to produce 78% of the force space producible through individual activation of the 42 modeled hindlimb muscles. This novel, neuroanatomically derived reduction in input dimension emphasizes the potential to simplify controllers for functional electrical stimulation to improve functional recovery after a neuromuscular injury.

Application of a Rat Hindlimb Model: A Prediction of Force Spaces Reachable Through Stimulation of Nerve Fascicles

PubMed Central

Johnson, Will L.; Jindrich, Devin L.; Zhong, Hui; Roy, Roland R.

2011-01-01

A device to generate standing or locomotion through chronically placed electrodes has not been fully developed due in part to limitations of clinical experimentation and the high number of muscle activation inputs of the leg. We investigated the feasibility of functional electrical stimulation paradigms that minimize the input dimensions for controlling the limbs by stimulating at nerve fascicles, utilizing a model of the rat hindlimb which combined previously collected morphological data with muscle physiological parameters presented herein. As validation of the model we investigated the suitability of a lumped-parameter model for prediction of muscle activation during dynamic tasks. Using the validated model we found that the space of forces producible through activation of muscle groups sharing common nerve fascicles was nonlinearly dependent on the number of discrete muscle groups that could be individually activated (equivalently, the neuroanatomical level of activation). Seven commonly innervated muscle groups were sufficient to produce 78% of the force space producible through individual activation of the 42 modeled hindlimb muscles. This novel, neuroanatomically derived reduction in input dimension emphasizes the potential to simplify controllers for functional electrical stimulation to improve functional recovery after a neuromuscular injury. PMID:21244999

Evaluation of SCS-CN method using a fully distributed physically based coupled surface-subsurface flow model

NASA Astrophysics Data System (ADS)

Shokri, Ali

2017-04-01

The hydrological cycle contains a wide range of linked surface and subsurface flow processes. In spite of natural connections between surface water and groundwater, historically, these processes have been studied separately. The current trend in hydrological distributed physically based model development is to combine distributed surface water models with distributed subsurface flow models. This combination results in a better estimation of the temporal and spatial variability of the interaction between surface and subsurface flow. On the other hand, simple lumped models such as the Soil Conservation Service Curve Number (SCS-CN) are still quite common because of their simplicity. In spite of the popularity of the SCS-CN method, there have always been concerns about the ambiguity of the SCS-CN method in explaining physical mechanism of rainfall-runoff processes. The aim of this study is to minimize these ambiguity by establishing a method to find an equivalence of the SCS-CN solution to the DrainFlow model, which is a fully distributed physically based coupled surface-subsurface flow model. In this paper, two hypothetical v-catchment tests are designed and the direct runoff from a storm event are calculated by both SCS-CN and DrainFlow models. To find a comparable solution to runoff prediction through the SCS-CN and DrainFlow, the variance between runoff predictions by the two models are minimized by changing Curve Number (CN) and initial abstraction (Ia) values. Results of this study have led to a set of lumped model parameters (CN and Ia) for each catchment that is comparable to a set of physically based parameters including hydraulic conductivity, Manning roughness coefficient, ground surface slope, and specific storage. Considering the lack of physical interpretation in CN and Ia is often argued as a weakness of SCS-CN method, the novel method in this paper gives a physical explanation to CN and Ia.

Optics-based compressibility parameter for pharmaceutical tablets obtained with the aid of the terahertz refractive index.

PubMed

Chakraborty, Mousumi; Ridgway, Cathy; Bawuah, Prince; Markl, Daniel; Gane, Patrick A C; Ketolainen, Jarkko; Zeitler, J Axel; Peiponen, Kai-Erik

2017-06-15

The objective of this study is to propose a novel optical compressibility parameter for porous pharmaceutical tablets. This parameter is defined with the aid of the effective refractive index of a tablet that is obtained from non-destructive and contactless terahertz (THz) time-delay transmission measurement. The optical compressibility parameter of two training sets of pharmaceutical tablets with a priori known porosity and mass fraction of a drug was investigated. Both pharmaceutical sets were compressed with one of the most commonly used excipients, namely microcrystalline cellulose (MCC) and drug Indomethacin. The optical compressibility clearly correlates with the skeletal bulk modulus determined by mercury porosimetry and the recently proposed terahertz lumped structural parameter calculated from terahertz measurements. This lumped structural parameter can be used to analyse the pattern of arrangement of excipient and drug particles in porous pharmaceutical tablets. Therefore, we propose that the optical compressibility can serve as a quality parameter of a pharmaceutical tablet corresponding with the skeletal bulk modulus of the porous tablet, which is related to structural arrangement of the powder particles in the tablet. Copyright © 2017 Elsevier B.V. All rights reserved.

Lie symmetry analysis, Bäcklund transformations, and exact solutions of a (2 + 1)-dimensional Boiti-Leon-Pempinelli system

NASA Astrophysics Data System (ADS)

Zhao, Zhonglong; Han, Bo

2017-10-01

In this paper, the Lie symmetry analysis method is employed to investigate the Lie point symmetries and the one-parameter transformation groups of a (2 + 1)-dimensional Boiti-Leon-Pempinelli system. By using Ibragimov's method, the optimal system of one-dimensional subalgebras of this system is constructed. Truncated Painlevé analysis is used for deriving the Bäcklund transformation. The method of constructing lump-type solutions of integrable equations by means of Bäcklund transformation is first presented. Meanwhile, the lump-type solutions of the (2 + 1)-dimensional Boiti-Leon-Pempinelli system are obtained. The lump-type wave is one kind of rogue wave. The fusion-type N-solitary wave solutions are also constructed. In addition, this system is integrable in terms of the consistent Riccati expansion method.

On a sparse pressure-flow rate condensation of rigid circulation models

PubMed Central

Schiavazzi, D. E.; Hsia, T. Y.; Marsden, A. L.

2015-01-01

Cardiovascular simulation has shown potential value in clinical decision-making, providing a framework to assess changes in hemodynamics produced by physiological and surgical alterations. State-of-the-art predictions are provided by deterministic multiscale numerical approaches coupling 3D finite element Navier Stokes simulations to lumped parameter circulation models governed by ODEs. Development of next-generation stochastic multiscale models whose parameters can be learned from available clinical data under uncertainty constitutes a research challenge made more difficult by the high computational cost typically associated with the solution of these models. We present a methodology for constructing reduced representations that condense the behavior of 3D anatomical models using outlet pressure-flow polynomial surrogates, based on multiscale model solutions spanning several heart cycles. Relevance vector machine regression is compared with maximum likelihood estimation, showing that sparse pressure/flow rate approximations offer superior performance in producing working surrogate models to be included in lumped circulation networks. Sensitivities of outlets flow rates are also quantified through a Sobol’ decomposition of their total variance encoded in the orthogonal polynomial expansion. Finally, we show that augmented lumped parameter models including the proposed surrogates accurately reproduce the response of multiscale models they were derived from. In particular, results are presented for models of the coronary circulation with closed loop boundary conditions and the abdominal aorta with open loop boundary conditions. PMID:26671219

Compartment Venting Analyses of Ares I First Stage Systems Tunnel

NASA Technical Reports Server (NTRS)

Wang, Qunzhen; Arner, Stephen

2009-01-01

Compartment venting analyses have been performed for the Ares I first stage systems tunnel using both the lumped parameter method and the three-dimensional (31)) transient computational fluid dynamics (CFD) approach. The main objective of venting analyses is to predict the magnitudes of differential pressures across the skin so the integrity of solid walls can be evaluated and properly designed. The lumped parameter method assumes the gas pressure and temperature inside the systems tunnel are spatially uniform, which is questionable since the tunnel is about 1,700 in. long and 4 in. wide. Therefore, 31) transient CFD simulations using the commercial CFD code FLUENT are performed in order to examine the gas pressure and temperature variations inside the tunnel. It was found that the uniform pressure and temperature assumptions inside the systems tunnel are valid during ascent. During reentry, the uniform pressure assumption is also reasonable but the uniform temperature assumption is not valid. Predicted pressure and temperature inside the systems tunnel using CFD are also compared with those from the lumped parameter method using the NASA code CHCHVENT. In general, the average pressure and temperature inside the systems tunnel from CFD are between the burst and crush results from CHCHVENT during both ascent and reentry. The skin differential pressure and pressure inside the systems tunnel relative to freestream pressure from CHCHVENT as well as velocity vectors and streamlines are also discussed in detail.

An application of PSO algorithm for multi-criteria geometry optimization of printed low-pass filters based on conductive periodic structures

NASA Astrophysics Data System (ADS)

Steckiewicz, Adam; Butrylo, Boguslaw

2017-08-01

In this paper we discussed the results of a multi-criteria optimization scheme as well as numerical calculations of periodic conductive structures with selected geometry. Thin printed structures embedded on a flexible dielectric substrate may be applied as simple, cheap, passive low-pass filters with an adjustable cutoff frequency in low (up to 1 MHz) radio frequency range. The analysis of an electromagnetic phenomena in presented structures was realized on the basis of a three-dimensional numerical model of three proposed geometries of periodic elements. The finite element method (FEM) was used to obtain a solution of an electromagnetic harmonic field. Equivalent lumped electrical parameters of printed cells obtained in such manner determine the shape of an amplitude transmission characteristic of a low-pass filter. A nonlinear influence of a printed cell geometry on equivalent parameters of cells electric model, makes it difficult to find the desired optimal solution. Therefore an optimization problem of optimal cell geometry estimation with regard to an approximation of the determined amplitude transmission characteristic with an adjusted cutoff frequency, was obtained by the particle swarm optimization (PSO) algorithm. A dynamically suitable inertia factor was also introduced into the algorithm to improve a convergence to a global extremity of a multimodal objective function. Numerical results as well as PSO simulation results were characterized in terms of approximation accuracy of predefined amplitude characteristics in a pass-band, stop-band and cutoff frequency. Three geometries of varying degrees of complexity were considered and their use in signal processing systems was evaluated.

Comparison of alternative designs for reducing complex neurons to equivalent cables.

PubMed

Burke, R E

2000-01-01

Reduction of the morphological complexity of actual neurons into accurate, computationally efficient surrogate models is an important problem in computational neuroscience. The present work explores the use of two morphoelectrotonic transformations, somatofugal voltage attenuation (AT cables) and signal propagation delay (DL cables), as bases for construction of electrotonically equivalent cable models of neurons. In theory, the AT and DL cables should provide more accurate lumping of membrane regions that have the same transmembrane potential than the familiar equivalent cables that are based only on somatofugal electrotonic distance (LM cables). In practice, AT and DL cables indeed provided more accurate simulations of the somatic transient responses produced by fully branched neuron models than LM cables. This was the case in the presence of a somatic shunt as well as when membrane resistivity was uniform.

Characterization of an air jet haptic lump display.

PubMed

Bianchi, Matteo; Gwilliam, James C; Degirmenci, Alperen; Okamura, Allison M

2011-01-01

During manual palpation, clinicians rely on distributed tactile information to identify and localize hard lumps embedded in soft tissue. The development of tactile feedback systems to enhance palpation using robot-assisted minimally invasive surgery (RMIS) systems is challenging due to size and weight constraints, motivating a pneumatic actuation strategy. Recently, an air jet approach has been proposed for generating a lump percept. We use this technique to direct a thin stream of air through an aperture directly on the finger pad, which indents the skin in a hemispherical manner, producing a compelling lump percept. We hypothesize that the perceived parameters of the lump (e.g. size and stiffness) can be controlled by jointly adjusting air pressure and the aperture size through which air escapes. In this work, we investigate how these control variables interact to affect perceived pressure on the finger pad. First, we used a capacitive tactile sensor array to measure the effect of aperture size on output pressure, and found that peak output pressure increases with aperture size. Second, we performed a psychophysical experiment for each aperture size to determine the just noticeable difference (JND) of air pressure on the finger pad. Subject-averaged pressure JND values ranged from 19.4-24.7 kPa, with no statistical differences observed between aperture sizes. The aperture-pressure relationship and the pressure JND values will be fundamental for future display control.

The urban energy balance of a lightweight low-rise neighborhood in Andacollo, Chile

NASA Astrophysics Data System (ADS)

Crawford, Ben; Krayenhoff, E. Scott; Cordy, Paul

2018-01-01

Worldwide, the majority of rapidly growing neighborhoods are found in the Global South. They often exhibit different building construction and development patterns than the Global North, and urban climate research in many such neighborhoods has to date been sparse. This study presents local-scale observations of net radiation ( Q * ) and sensible heat flux ( Q H ) from a lightweight low-rise neighborhood in the desert climate of Andacollo, Chile, and compares observations with results from a process-based urban energy-balance model (TUF3D) and a local-scale empirical model (LUMPS) for a 14-day period in autumn 2009. This is a unique neighborhood-climate combination in the urban energy-balance literature, and results show good agreement between observations and models for Q * and Q H . The unmeasured latent heat flux ( Q E ) is modeled with an updated version of TUF3D and two versions of LUMPS (a forward and inverse application). Both LUMPS implementations predict slightly higher Q E than TUF3D, which may indicate a bias in LUMPS parameters towards mid-latitude, non-desert climates. Overall, the energy balance is dominated by sensible and storage heat fluxes with mean daytime Bowen ratios of 2.57 (observed Q H /LUMPS Q E )-3.46 (TUF3D). Storage heat flux ( ΔQ S ) is modeled with TUF3D, the empirical objective hysteresis model (OHM), and the inverse LUMPS implementation. Agreement between models is generally good; the OHM-predicted diurnal cycle deviates somewhat relative to the other two models, likely because OHM coefficients are not specified for the roof and wall construction materials found in this neighborhood. New facet-scale and local-scale OHM coefficients are developed based on modeled ΔQ S and observed Q * . Coefficients in the empirical models OHM and LUMPS are derived from observations in primarily non-desert climates in European/North American neighborhoods and must be updated as measurements in lightweight low-rise (and other) neighborhoods in various climates become available.

Fluctuation relations between hierarchical kinetically equivalent networks with Arrhenius-type transitions and their roles in systems and structural biology.

PubMed

Deng, De-Ming; Lu, Yi-Ta; Chang, Cheng-Hung

2017-06-01

The legality of using simple kinetic schemes to determine the stochastic properties of a complex system depends on whether the fluctuations generated from hierarchical equivalent schemes are consistent with one another. To analyze this consistency, we perform lumping processes on the stochastic differential equations and the generalized fluctuation-dissipation theorem and apply them to networks with the frequently encountered Arrhenius-type transition rates. The explicit Langevin force derived from those networks enables us to calculate the state fluctuations caused by the intrinsic and extrinsic noises on the free energy surface and deduce their relations between kinetically equivalent networks. In addition to its applicability to wide classes of network related systems, such as those in structural and systems biology, the result sheds light on the fluctuation relations for general physical variables in Keizer's canonical theory.

Observation time scale, free-energy landscapes, and molecular symmetry

PubMed Central

Wales, David J.; Salamon, Peter

2014-01-01

When structures that interconvert on a given time scale are lumped together, the corresponding free-energy surface becomes a function of the observation time. This view is equivalent to grouping structures that are connected by free-energy barriers below a certain threshold. We illustrate this time dependence for some benchmark systems, namely atomic clusters and alanine dipeptide, highlighting the connections to broken ergodicity, local equilibrium, and “feasible” symmetry operations of the molecular Hamiltonian. PMID:24374625

Transient Behavior of Lumped-Constant Systems for Sensing Gas Pressures

NASA Technical Reports Server (NTRS)

Delio, Gene J; Schwent, Glennon V; Cesaro, Richard S

1949-01-01

The development of theoretical equations describing the behavior of a lumped-constant pressure-sensing system under transient operation Is presented with experimental data that show agreement with the equations. A pressure-sensing system 'consisting of a tube terminating in a reservoir is investigated for the transient relation between a presSure disturbance at the open end of the tube and the pressure response in the reservoir. Design parameters are presented that can be adjusted to achieve a desired performance fran such a system when the system is considered as a transfer member of a control loop.

Model reduction for experimental thermal characterization of a holding furnace

NASA Astrophysics Data System (ADS)

Loussouarn, Thomas; Maillet, Denis; Remy, Benjamin; Dan, Diane

2017-09-01

Vacuum holding induction furnaces are used for the manufacturing of turbine blades by loss wax foundry process. The control of solidification parameters is a key factor for the manufacturing of these parts. The definition of the structure of a reduced heat transfer model with experimental identification through an estimation of its parameters is required here. Internal sensors outputs, together with this model, can be used for assessing the thermal state of the furnace through an inverse approach, for a better control. Here, an axisymmetric furnace and its load have been numerically modelled using FlexPDE, a finite elements code. The internal induction heat source as well as the transient radiative transfer inside the furnace are calculated through this detailed model. A reduced lumped body model has been constructed to represent the numerical furnace. The model reduction and the estimation of the parameters of the lumped body have been made using a Levenberg-Marquardt least squares minimization algorithm, using two synthetic temperature signals with a further validation test.

Frequency analysis of a two-stage planetary gearbox using two different methodologies

NASA Astrophysics Data System (ADS)

Feki, Nabih; Karray, Maha; Khabou, Mohamed Tawfik; Chaari, Fakher; Haddar, Mohamed

2017-12-01

This paper is focused on the characterization of the frequency content of vibration signals issued from a two-stage planetary gearbox. To achieve this goal, two different methodologies are adopted: the lumped-parameter modeling approach and the phenomenological modeling approach. The two methodologies aim to describe the complex vibrations generated by a two-stage planetary gearbox. The phenomenological model describes directly the vibrations as measured by a sensor fixed outside the fixed ring gear with respect to an inertial reference frame, while results from a lumped-parameter model are referenced with respect to a rotating frame and then transferred into an inertial reference frame. Two different case studies of the two-stage planetary gear are adopted to describe the vibration and the corresponding spectra using both models. Each case presents a specific geometry and a specific spectral structure.

VIIP: Central Nervous System (CNS) Modeling

NASA Technical Reports Server (NTRS)

Vera, Jerry; Mulugeta, Lealem; Nelson, Emily; Raykin, Julia; Feola, Andrew; Gleason, Rudy; Samuels, Brian; Ethier, C. Ross; Myers, Jerry

2015-01-01

Current long-duration missions to the International Space Station and future exploration-class missions beyond low-Earth orbit expose astronauts to increased risk of Visual Impairment and Intracranial Pressure (VIIP) syndrome. It has been hypothesized that the headward shift of cerebrospinal fluid (CSF) and blood in microgravity may cause significant elevation of intracranial pressure (ICP), which in turn may then induce VIIP syndrome through interaction with various biomechanical pathways. However, there is insufficient evidence to confirm this hypothesis. In this light, we are developing lumped-parameter models of fluid transport in the central nervous system (CNS) as a means to simulate the influence of microgravity on ICP. The CNS models will also be used in concert with the lumped parameter and finite element models of the eye described in the related IWS works submitted by Nelson et al., Feola et al. and Ethier et al.

Development of a hybrid (numerical-hydraulic) circulatory model: prototype testing and its response to IABP assistance.

PubMed

Ferrari, G; Kozarski, M; De Lazzari, C; Górczyńska, K; Tosti, G; Darowski, M

2005-07-01

Merging numerical and physical models of the circulation makes it possible to develop a new class of circulatory models defined as hybrid. This solution reduces the costs, enhances the flexibility and opens the way to many applications ranging from research to education and heart assist devices testing. In the prototype described in this paper, a hydraulic model of systemic arterial tree is connected to a lumped parameters numerical model including pulmonary circulation and the remaining parts of systemic circulation. The hydraulic model consists of a characteristic resistance, of a silicon rubber tube to allow the insertion of an Intra-Aortic Balloon Pump (IABP) and of a lumped parameters compliance. Two electro-hydraulic interfaces, realized by means of gear pumps driven by DC motors, connect the numerical section with both terminals of the hydraulic section. The lumped parameters numerical model and the control system (including analog to digital and digital to analog converters)are developed in LabVIEW environment. The behavior of the model is analyzed by means of the ventricular pressure-volume loops and the time courses of arterial and ventricular pressures and flows in different circulatory conditions. A simulated pathological condition was set to test the IABP and verify the response of the system to this type of mechanical circulatory assistance. The results show that the model can represent hemodynamic relationships in different ventricular and circulatory conditions and is able to react to the IABP assistance.

Deflection Analysis of the Space Shuttle External Tank Door Drive Mechanism

NASA Technical Reports Server (NTRS)

Tosto, Michael A.; Trieu, Bo C.; Evernden, Brent A.; Hope, Drew J.; Wong, Kenneth A.; Lindberg, Robert E.

2008-01-01

Upon observing an abnormal closure of the Space Shuttle s External Tank Doors (ETD), a dynamic model was created in MSC/ADAMS to conduct deflection analyses of the Door Drive Mechanism (DDM). For a similar analysis, the traditional approach would be to construct a full finite element model of the mechanism. The purpose of this paper is to describe an alternative approach that models the flexibility of the DDM using a lumped parameter approximation to capture the compliance of individual parts within the drive linkage. This approach allows for rapid construction of a dynamic model in a time-critical setting, while still retaining the appropriate equivalent stiffness of each linkage component. As a validation of these equivalent stiffnesses, finite element analysis (FEA) was used to iteratively update the model towards convergence. Following this analysis, deflections recovered from the dynamic model can be used to calculate stress and classify each component s deformation as either elastic or plastic. Based on the modeling assumptions used in this analysis and the maximum input forcing condition, two components in the DDM show a factor of safety less than or equal to 0.5. However, to accurately evaluate the induced stresses, additional mechanism rigging information would be necessary to characterize the input forcing conditions. This information would also allow for the classification of stresses as either elastic or plastic.

Interpretation of environmental tracers in groundwater systems with stagnant water zones.

PubMed

Maloszewski, Piotr; Stichler, Willibald; Zuber, Andrzej

2004-03-01

Lumped-parameter models are commonly applied for determining the age of water from time records of transient environmental tracers. The simplest models (e.g. piston flow or exponential) are also applicable for dating based on the decay or accumulation of tracers in groundwater systems. The models are based on the assumption that the transit time distribution function (exit age distribution function) of the tracer particles in the investigated system adequately represents the distribution of flow lines and is described by a simple function. A chosen or fitted function (called the response function) describes the transit time distribution of a tracer which would be observed at the output (discharge area, spring, stream, or pumping wells) in the case of an instantaneous injection at the entrance (recharge area). Due to large space and time scales, response functions are not measurable in groundwater systems, therefore, functions known from other fields of science, mainly from chemical engineering, are usually used. The type of response function and the values of its parameters define the lumped-parameter model of a system. The main parameter is the mean transit time of tracer through the system, which under favourable conditions may represent the mean age of mobile water. The parameters of the model are found by fitting calculated concentrations to the experimental records of concentrations measured at the outlet. The mean transit time of tracer (often called the tracer age), whether equal to the mean age of water or not, serves in adequate combinations with other data for determining other useful parameters, e.g. the recharge rate or the content of water in the system. The transit time distribution and its mean value serve for confirmation or determination of the conceptual model of the system and/or estimation of its potential vulnerability to anthropogenic pollution. In the interpretation of environmental tracer data with the aid of the lumped-parameter models, the influence of diffusion exchange between mobile water and stagnant or quasi-stagnant water is seldom considered, though it leads to large differences between tracer and water ages. Therefore, the article is focused on the transit time distribution functions of the most common lumped-parameter models, particularly those applicable for the interpretation of environmental tracer data in double-porosity aquifers, or aquifers in which aquitard diffusion may play an important role. A case study is recalled for a confined aquifer in which the diffusion exchange with aquitard most probably strongly influenced the transport of environmental tracers. Another case study presented is related to the interpretation of environmental tracer data obtained from lysimeters installed in the unsaturated zone with a fraction of stagnant water.

Coupled magneto-electro-mechanical lumped parameter model for a novel vibration-based magneto-electro-elastic energy harvesting systems

NASA Astrophysics Data System (ADS)

Shirbani, Meisam Moory; Shishesaz, Mohammad; Hajnayeb, Ali; Sedighi, Hamid Mohammad

2017-06-01

The objective of this paper is to present a coupled magneto-electro-mechanical (MEM) lumped parameter model for the response of the proposed magneto-electro-elastic (MEE) energy harvesting systems under base excitation. The proposed model can be used to create self-powering systems, which are not limited to a finite battery energy. As a novel approach, the MEE composites are used instead of the conventional piezoelectric materials in order to enhance the harvested electrical power. The considered structure consists of a MEE layer deposited on a layer of non-MEE material, in the framework of unimorph cantilever bars (longitudinal displacement) and beams (transverse displacement). To use the generated electrical potential, two electrodes are connected to the top and bottom surfaces of the MEE layer. Additionally, a stationary external coil is wrapped around the vibrating structure to induce a voltage in the coil by the magnetic field generated in the MEE layer. In order to simplify the design procedure of the proposed energy harvester and obtain closed form solutions, a lumped parameter model is prepared. As a first step in modeling process, the governing constitutive equations, Gauss's and Faraday's laws, are used to derive the coupled MEM differential equations. The derived equations are then solved analytically to obtain the dynamic behavior and the harvested voltages and powers of the proposed energy harvesting systems. Finally, the influences of the parameters that affect the performance of the MEE energy harvesters such as excitation frequency, external resistive loads and number of coil turns are discussed in detail. The results clearly show the benefit of the coil circuit implementation, whereby significant increases in the total useful harvested power as much as 38% and 36% are obtained for the beam and bar systems, respectively.

Modelling chemical depletion profiles in regolith

USGS Publications Warehouse

Brantley, S.L.; Bandstra, J.; Moore, J.; White, A.F.

2008-01-01

Chemical or mineralogical profiles in regolith display reaction fronts that document depletion of leachable elements or minerals. A generalized equation employing lumped parameters was derived to model such ubiquitously observed patterns:C = frac(C0, frac(C0 - Cx = 0, Cx = 0) exp (??ini ?? over(k, ??) ?? x) + 1)Here C, Cx = 0, and Co are the concentrations of an element at a given depth x, at the top of the reaction front, or in parent respectively. ??ini is the roughness of the dissolving mineral in the parent and k???? is a lumped kinetic parameter. This kinetic parameter is an inverse function of the porefluid advective velocity and a direct function of the dissolution rate constant times mineral surface area per unit volume regolith. This model equation fits profiles of concentration versus depth for albite in seven weathering systems and is consistent with the interpretation that the surface area (m2 mineral m- 3 bulk regolith) varies linearly with the concentration of the dissolving mineral across the front. Dissolution rate constants can be calculated from the lumped fit parameters for these profiles using observed values of weathering advance rate, the proton driving force, the geometric surface area per unit volume regolith and parent concentration of albite. These calculated values of the dissolution rate constant compare favorably to literature values. The model equation, useful for reaction fronts in both steady-state erosional and quasi-stationary non-erosional systems, incorporates the variation of reaction affinity using pH as a master variable. Use of this model equation to fit depletion fronts for soils highlights the importance of buffering of pH in the soil system. Furthermore, the equation should allow better understanding of the effects of important environmental variables on weathering rates. ?? 2008.

Lumped versus distributed thermoregulatory control: results from a three-dimensional dynamic model.

PubMed

Werner, J; Buse, M; Foegen, A

1989-01-01

In this study we use a three-dimensional model of the human thermal system, the spatial grid of which is 0.5 ... 1.0 cm. The model is based on well-known physical heat-transfer equations, and all parameters of the passive system have definite physical values. According to the number of substantially different areas and organs, 54 spatially different values are attributed to each physical parameter. Compatibility of simulation and experiment was achieved solely on the basis of physical considerations and physiological basic data. The equations were solved using a modification of the alternating direction implicit method. On the basis of this complex description of the passive system close to reality, various lumped and distributed parameter control equations were tested for control of metabolic heat production, blood flow and sweat production. The simplest control equations delivering results on closed-loop control compatible with experimental evidence were determined. It was concluded that it is essential to take into account the spatial distribution of heat production, blood flow and sweat production, and that at least for control of shivering, distributed controller gains different from the pattern of distribution of muscle tissue are required. For sweat production this is not so obvious, so that for simulation of sweating control after homogeneous heat load a lumped parameter control may be justified. Based on these conclusions three-dimensional temperature profiles for cold and heat load and the dynamics for changes of the environmental conditions were computed. In view of the exact simulation of the passive system and the compatibility with experimentally attainable variables there is good evidence that those values extrapolated by the simulation are adequately determined. The model may be used both for further analysis of the real thermoregulatory mechanisms and for special applications in environmental and clinical health care.

Design and performance of dual-polarization lumped-element kinetic inductance detectors for millimeter-wave polarimetry

NASA Astrophysics Data System (ADS)

McCarrick, H.; Jones, G.; Johnson, B. R.; Abitbol, M. H.; Ade, P. A. R.; Bryan, S.; Day, P.; Essinger-Hileman, T.; Flanigan, D.; Leduc, H. G.; Limon, M.; Mauskopf, P.; Miller, A.; Tucker, C.

2018-02-01

Aims: Lumped-element kinetic inductance detectors (LEKIDs) are an attractive technology for millimeter-wave observations that require large arrays of extremely low-noise detectors. We designed, fabricated and characterized 64-element (128 LEKID) arrays of horn-coupled, dual-polarization LEKIDs optimized for ground-based CMB polarimetry. Our devices are sensitive to two orthogonal polarizations in a single spectral band centered on 150 GHz with Δν/ν = 0.2. The 65 × 65 mm square arrays are designed to be tiled into the focal plane of an optical system. We demonstrate the viability of these dual-polarization LEKIDs with laboratory measurements. Methods: The LEKID modules are tested with an FPGA-based readout system in a sub-kelvin cryostat that uses a two-stage adiabatic demagnetization refrigerator. The devices are characterized using a blackbody and a millimeter-wave source. The polarization properties are measured with a cryogenic stepped half-wave plate. We measure the resonator parameters and the detector sensitivity, noise spectrum, dynamic range, and polarization response. Results: The resonators have internal quality factors approaching 1 × 106. The detectors have uniform response between orthogonal polarizations and a large dynamic range. The detectors are photon-noise limited above 1 pW of absorbed power. The noise-equivalent temperatures under a 3.4 K blackbody load are <100 μK √s. The polarization fractions of detectors sensitive to orthogonal polarizations are >80%. The entire array is multiplexed on a single readout line, demonstrating a multiplexing factor of 128. The array and readout meet the requirements for 4 arrays to be read out simultaneously for a multiplexing factor of 512. Conclusions: This laboratory study demonstrates the first dual-polarization LEKID array optimized specifically for CMB polarimetry and shows the readiness of the detectors for on-sky observations.

Photon noise from chaotic and coherent millimeter-wave sources measured with horn-coupled, aluminum lumped-element kinetic inductance detectors

NASA Astrophysics Data System (ADS)

Flanigan, D.; McCarrick, H.; Jones, G.; Johnson, B. R.; Abitbol, M. H.; Ade, P.; Araujo, D.; Bradford, K.; Cantor, R.; Che, G.; Day, P.; Doyle, S.; Kjellstrand, C. B.; Leduc, H.; Limon, M.; Luu, V.; Mauskopf, P.; Miller, A.; Mroczkowski, T.; Tucker, C.; Zmuidzinas, J.

2016-02-01

We report photon-noise limited performance of horn-coupled, aluminum lumped-element kinetic inductance detectors at millimeter wavelengths. The detectors are illuminated by a millimeter-wave source that uses an active multiplier chain to produce radiation between 140 and 160 GHz. We feed the multiplier with either amplified broadband noise or a continuous-wave tone from a microwave signal generator. We demonstrate that the detector response over a 40 dB range of source power is well-described by a simple model that considers the number of quasiparticles. The detector noise-equivalent power (NEP) is dominated by photon noise when the absorbed power is greater than approximately 1 pW, which corresponds to NEP≈2 ×10-17 W Hz-1 /2 , referenced to absorbed power. At higher source power levels, we observe the relationships between noise and power expected from the photon statistics of the source signal: NEP∝P for broadband (chaotic) illumination and NEP∝P1 /2 for continuous-wave (coherent) illumination.

Horn-coupled, commercially-fabricated aluminum lumped-element kinetic inductance detectors for millimeter wavelengths

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

McCarrick, H., E-mail: hlm2124@columbia.edu; Flanigan, D.; Jones, G.

We discuss the design, fabrication, and testing of prototype horn-coupled, lumped-element kinetic inductance detectors (LEKIDs) designed for cosmic microwave background studies. The LEKIDs are made from a thin aluminum film deposited on a silicon wafer and patterned using standard photolithographic techniques at STAR Cryoelectronics, a commercial device foundry. We fabricated 20-element arrays, optimized for a spectral band centered on 150 GHz, to test the sensitivity and yield of the devices as well as the multiplexing scheme. We characterized the detectors in two configurations. First, the detectors were tested in a dark environment with the horn apertures covered, and second, themore » horn apertures were pointed towards a beam-filling cryogenic blackbody load. These tests show that the multiplexing scheme is robust and scalable, the yield across multiple LEKID arrays is 91%, and the measured noise-equivalent temperatures for a 4 K optical load are in the range 26±6 μK√(s)« less

Theoretical study of a thermo-acousto-electric generator equipped with an electroacoustic feedback loop

NASA Astrophysics Data System (ADS)

Olivier, Come; Penelet, Guillaume; Poignand, Gaelle; Lotton, Pierrick

2015-10-01

A simplified model of a Stirling-type thermoacoustic engine coupled to a resonant mechanical system is presented. The acoustic network is presented as its temperature-dependent lumped element equivalent, and the nonlinear effects involved in such engines are accounted for in a nonlinear heat equation governing the temperature distribution through the thermoacoustic core. The low-order model is sufficient to capture the behavior of the engine, both in terms of stability and dynamic behavior.

Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations.

PubMed

Safaei, Soroush; Blanco, Pablo J; Müller, Lucas O; Hellevik, Leif R; Hunter, Peter J

2018-01-01

We propose a detailed CellML model of the human cerebral circulation that runs faster than real time on a desktop computer and is designed for use in clinical settings when the speed of response is important. A lumped parameter mathematical model, which is based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, is constructed using a bond graph formulation to ensure mass conservation and energy conservation. The model includes arterial vessels with geometric and anatomical data based on the ADAN circulation model. The peripheral beds are represented by lumped parameter compartments. We compare the hemodynamics predicted by the bond graph formulation of the cerebral circulation with that given by a classical one-dimensional Navier-Stokes model working on top of the whole-body ADAN model. Outputs from the bond graph model, including the pressure and flow signatures and blood volumes, are compared with physiological data.

A lumped parameter mathematical model for simulation of subsonic wind tunnels

NASA Technical Reports Server (NTRS)

Krosel, S. M.; Cole, G. L.; Bruton, W. M.; Szuch, J. R.

1986-01-01

Equations for a lumped parameter mathematical model of a subsonic wind tunnel circuit are presented. The equation state variables are internal energy, density, and mass flow rate. The circuit model is structured to allow for integration and analysis of tunnel subsystem models which provide functions such as control of altitude pressure and temperature. Thus the model provides a useful tool for investigating the transient behavior of the tunnel and control requirements. The model was applied to the proposed NASA Lewis Altitude Wind Tunnel (AWT) circuit and included transfer function representations of the tunnel supply/exhaust air and refrigeration subsystems. Both steady state and frequency response data are presented for the circuit model indicating the type of results and accuracy that can be expected from the model. Transient data for closed loop control of the tunnel and its subsystems are also presented, demonstrating the model's use as a control analysis tool.

Method And Apparatus For Two Dimensional Surface Property Analysis Based On Boundary Measurement

DOEpatents

Richardson, John G.

2005-11-15

An apparatus and method for determining properties of a conductive film is disclosed. A plurality of probe locations selected around a periphery of the conductive film define a plurality of measurement lines between each probe location and all other probe locations. Electrical resistance may be measured along each of the measurement lines. A lumped parameter model may be developed based on the measured values of electrical resistance. The lumped parameter model may be used to estimate resistivity at one or more selected locations encompassed by the plurality of probe locations. The resistivity may be extrapolated to other physical properties if the conductive film includes a correlation between resistivity and the other physical properties. A profile of the conductive film may be developed by determining resistivity at a plurality of locations. The conductive film may be applied to a structure such that resistivity may be estimated and profiled for the structure's surface.

A new lumped-parameter approach to simulating flow processes in unsaturated dual-porosity media

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

Zimmerman, R.W.; Hadgu, T.; Bodvarsson, G.S.

We have developed a new lumped-parameter dual-porosity approach to simulating unsaturated flow processes in fractured rocks. Fluid flow between the fracture network and the matrix blocks is described by a nonlinear equation that relates the imbibition rate to the local difference in liquid-phase pressure between the fractures and the matrix blocks. This equation is a generalization of the Warren-Root equation, but unlike the Warren-Root equation, is accurate in both the early and late time regimes. The fracture/matrix interflow equation has been incorporated into a computational module, compatible with the TOUGH simulator, to serve as a source/sink term for fracture elements.more » The new approach achieves accuracy comparable to simulations in which the matrix blocks are discretized, but typically requires an order of magnitude less computational time.« less

Rogue wave and a pair of resonance stripe solitons to a reduced (3+1)-dimensional Jimbo-Miwa equation

NASA Astrophysics Data System (ADS)

Zhang, Xiaoen; Chen, Yong

2017-11-01

In this paper, a combination of stripe soliton and lump soliton is discussed to a reduced (3+1)-dimensional Jimbo-Miwa equation, in which such solution gives rise to two different excitation phenomena: fusion and fission. Particularly, a new combination of positive quadratic functions and hyperbolic functions is considered, and then a novel nonlinear phenomenon is explored. Via this method, a pair of resonance kink stripe solitons and rogue wave is studied. Rogue wave is triggered by the interaction between lump soliton and a pair of resonance kink stripe solitons. It is exciting that rogue wave must be attached to the stripe solitons from its appearing to disappearing. The whole progress is completely symmetry, the rogue wave starts itself from one stripe soliton and lose itself in another stripe soliton. The dynamic properties of the interaction between one stripe soliton and lump soliton, rogue wave are discussed by choosing appropriate parameters.

A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells

USGS Publications Warehouse

Jurgens, Bryant; Böhlke, John Karl; Kauffman, Leon J.; Belitz, Kenneth; Esser, Bradley K.

2016-01-01

A partial exponential lumped parameter model (PEM) was derived to determine age distributions and nitrate trends in long-screened production wells. The PEM can simulate age distributions for wells screened over any finite interval of an aquifer that has an exponential distribution of age with depth. The PEM has 3 parameters – the ratio of saturated thickness to the top and bottom of the screen and mean age, but these can be reduced to 1 parameter (mean age) by using well construction information and estimates of the saturated thickness. The PEM was tested with data from 30 production wells in a heterogeneous alluvial fan aquifer in California, USA. Well construction data were used to guide parameterization of a PEM for each well and mean age was calibrated to measured environmental tracer data (3H, 3He, CFC-113, and 14C). Results were compared to age distributions generated for individual wells using advective particle tracking models (PTMs). Age distributions from PTMs were more complex than PEM distributions, but PEMs provided better fits to tracer data, partly because the PTMs did not simulate 14C accurately in wells that captured varying amounts of old groundwater recharged at lower rates prior to groundwater development and irrigation. Nitrate trends were simulated independently of the calibration process and the PEM provided good fits for at least 11 of 24 wells. This work shows that the PEM, and lumped parameter models (LPMs) in general, can often identify critical features of the age distributions in wells that are needed to explain observed tracer data and nonpoint source contaminant trends, even in systems where aquifer heterogeneity and water-use complicate distributions of age. While accurate PTMs are preferable for understanding and predicting aquifer-scale responses to water use and contaminant transport, LPMs can be sensitive to local conditions near individual wells that may be inaccurately represented or missing in an aquifer-scale flow model.

Lump, periodic lump and interaction lump stripe solutions to the (2+1)-dimensional B-type Kadomtsev-Petviashvili equation

NASA Astrophysics Data System (ADS)

Wu, Pinxia; Zhang, Yufeng; Muhammad, Iqbal; Yin, Qiqi

2018-03-01

In this paper, the Hirota’s bilinear form is employed to investigate the lump, periodic lump and interaction lump stripe solutions of the (2+1)-dimensional B-type Kadomtsev-Petviashvili (BKP) equation. Many results are obtained by dynamic process of figures. We analyze the propagation direction and horizontal velocity of lump solutions to find some constraint conditions which include positiveness and localization. In the process of the travel of the periodic lump solutions, it appears that the energy distribution is not symmetrical. The interaction lump stripe solutions of non-elastic indicate that the lump solitons are dropped and swallowed by the stripe soliton.

Uncertainty Quantification in Multi-Scale Coronary Simulations Using Multi-resolution Expansion

NASA Astrophysics Data System (ADS)

Tran, Justin; Schiavazzi, Daniele; Ramachandra, Abhay; Kahn, Andrew; Marsden, Alison

2016-11-01

Computational simulations of coronary flow can provide non-invasive information on hemodynamics that can aid in surgical planning and research on disease propagation. In this study, patient-specific geometries of the aorta and coronary arteries are constructed from CT imaging data and finite element flow simulations are carried out using the open source software SimVascular. Lumped parameter networks (LPN), consisting of circuit representations of vascular hemodynamics and coronary physiology, are used as coupled boundary conditions for the solver. The outputs of these simulations depend on a set of clinically-derived input parameters that define the geometry and boundary conditions, however their values are subjected to uncertainty. We quantify the effects of uncertainty from two sources: uncertainty in the material properties of the vessel wall and uncertainty in the lumped parameter models whose values are estimated by assimilating patient-specific clinical and literature data. We use a generalized multi-resolution chaos approach to propagate the uncertainty. The advantages of this approach lies in its ability to support inputs sampled from arbitrary distributions and its built-in adaptivity that efficiently approximates stochastic responses characterized by steep gradients.

Implementation of a numerical holding furnace model in foundry and construction of a reduced model

NASA Astrophysics Data System (ADS)

Loussouarn, Thomas; Maillet, Denis; Remy, Benjamin; Dan, Diane

2016-09-01

Vacuum holding induction furnaces are used for the manufacturing of turbine blades by loss wax foundry process. The control of solidification parameters is a key factor for the manufacturing of these parts in according to geometrical and structural expectations. The definition of a reduced heat transfer model with experimental identification through an estimation of its parameters is required here. In a further stage this model will be used to characterize heat exchanges using internal sensors through inverse techniques to optimize the furnace command and the optimization of its design. Here, an axisymmetric furnace and its load have been numerically modelled using FlexPDE, a finite elements code. A detailed model allows the calculation of the internal induction heat source as well as transient radiative transfer inside the furnace. A reduced lumped body model has been defined to represent the numerical furnace. The model reduction and the estimation of the parameters of the lumped body have been made using a Levenberg-Marquardt least squares minimization algorithm with Matlab, using two synthetic temperature signals with a further validation test.

Simulation of adaptive semi-active magnetorheological seat damper for vehicle occupant blast protection

NASA Astrophysics Data System (ADS)

Yoo, Jin-Hyeong; Murugan, Muthuvel; Wereley, Norman M.

2013-04-01

This study investigates a lumped-parameter human body model which includes lower leg in seated posture within a quarter-car model for blast injury assessment simulation. To simulate the shock acceleration of the vehicle, mine blast analysis was conducted on a generic land vehicle crew compartment (sand box) structure. For the purpose of simulating human body dynamics with non-linear parameters, a physical model of a lumped-parameter human body within a quarter car model was implemented using multi-body dynamic simulation software. For implementing the control scheme, a skyhook algorithm was made to work with the multi-body dynamic model by running a co-simulation with the control scheme software plug-in. The injury criteria and tolerance levels for the biomechanical effects are discussed for each of the identified vulnerable body regions, such as the relative head displacement and the neck bending moment. The desired objective of this analytical model development is to study the performance of adaptive semi-active magnetorheological damper that can be used for vehicle-occupant protection technology enhancements to the seat design in a mine-resistant military vehicle.

Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer

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

Sethuraman, Latha; Keller, Jonathan; Wallen, Robb

2016-08-31

This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is presented in two parts beginning with the identification of the primary torsional modes followed by the investigation of approaches to damp the torsional vibrations. The key mechanical parameters for the lumped parameter models and justification for the element grouping used in the derivation of the torsional modes are presented. The sensitivities of the torsional modes to different test article properties are discussed. The oscillations observed from the low-speed andmore » generator torque measurements were used to identify the extent of damping inherently achieved through active and passive compensation techniques. A simplified Simulink model of the dynamometer test article integrating the electro-mechanical power conversion and control features was established to emulate the torque behavior that was observed during testing. The torque response in the high-speed, low-speed, and generator shafts were tested and validated against experimental measurements involving step changes in load with the dynamometer operating under speed-regulation mode. The Simulink model serves as a ready reference to identify the torque sensitivities to various system parameters and to explore opportunities to improve torsional damping under different conditions.« less

Impact of model structure on flow simulation and hydrological realism: from a lumped to a semi-distributed approach

NASA Astrophysics Data System (ADS)

Garavaglia, Federico; Le Lay, Matthieu; Gottardi, Fréderic; Garçon, Rémy; Gailhard, Joël; Paquet, Emmanuel; Mathevet, Thibault

2017-08-01

Model intercomparison experiments are widely used to investigate and improve hydrological model performance. However, a study based only on runoff simulation is not sufficient to discriminate between different model structures. Hence, there is a need to improve hydrological models for specific streamflow signatures (e.g., low and high flow) and multi-variable predictions (e.g., soil moisture, snow and groundwater). This study assesses the impact of model structure on flow simulation and hydrological realism using three versions of a hydrological model called MORDOR: the historical lumped structure and a revisited formulation available in both lumped and semi-distributed structures. In particular, the main goal of this paper is to investigate the relative impact of model equations and spatial discretization on flow simulation, snowpack representation and evapotranspiration estimation. Comparison of the models is based on an extensive dataset composed of 50 catchments located in French mountainous regions. The evaluation framework is founded on a multi-criterion split-sample strategy. All models were calibrated using an automatic optimization method based on an efficient genetic algorithm. The evaluation framework is enriched by the assessment of snow and evapotranspiration modeling against in situ and satellite data. The results showed that the new model formulations perform significantly better than the initial one in terms of the various streamflow signatures, snow and evapotranspiration predictions. The semi-distributed approach provides better calibration-validation performance for the snow cover area, snow water equivalent and runoff simulation, especially for nival catchments.

Analysis of stability and bifurcations of fixed points and periodic solutions of a lumped model of neocortex with two delays

PubMed Central

2012-01-01

A lumped model of neural activity in neocortex is studied to identify regions of multi-stability of both steady states and periodic solutions. Presence of both steady states and periodic solutions is considered to correspond with epileptogenesis. The model, which consists of two delay differential equations with two fixed time lags is mainly studied for its dependency on varying connection strength between populations. Equilibria are identified, and using linear stability analysis, all transitions are determined under which both trivial and non-trivial fixed points lose stability. Periodic solutions arising at some of these bifurcations are numerically studied with a two-parameter bifurcation analysis. PMID:22655859

Lumped Parameter Models of the Central Nervous System for VIIP Research

NASA Technical Reports Server (NTRS)

Vera, J.; Mulugeta, L.; Nelson, E. S.; Raykin, J.; Feola, A.; Gleason, R.; Samuels, B.; Myers, J. G.

2015-01-01

INTRODUCTION: Current long-duration missions to the International Space Station and future exploration-class missions beyond low-Earth orbit, such as to Mars and asteroids, expose astronauts to increased risk of Visual Impairment and Intracranial Pressure (VIIP) syndrome [1]. It has been hypothesized that the headward shift of cerebral spinal fluid (CSF) and blood in microgravity may cause significant elevation of intracranial pressure (ICP), which in turn induces VIIP syndrome through biomechanical pathways [1, 2]. However, there is insufficient evidence to confirm this hypothesis. In this light, we are developing lumped-parameter models of fluid transport in the central nervous system (CNS) as a means to simulate the influence of microgravity on ICP. The CNS models will also be used in concert with the lumped parameter and finite element models of the eye described in the realted IWS abstracts submitted by Nelson et al., Feola et al. and Ethier et al. METHODS: We have developed a nine compartment CNS model (Figure 1) capable of both time-dependent and steady state fluid transport simulations, based on the works of Stevens et al. [3]. The breakdown of compartments within the model includes: vascular (3), CSF (2), brain (1) and extracranial (3). The boundary pressure in the Central Arteries [A] node is prescribed using an oscillating pressure function PA(t) simulating the carotid pulsatile pressure wave as developed by Linninger et al. [4]. For each time step, pressures are integrated through time using an adaptive-timestep 4th and 5th order Runga-Kutta solver. Once pressures are found, constitutive equations are used to solve for flowrates (Q) between each compartment. In addition to fluid flow between the different compartments, compliance (C) interactions between neighboring compartments are represented. We are also developing a second CNS model based on the works of Linninger et al. [4] which takes a more granular approach to represent the interactions of the intracranial and spinal compartments with the inclusion of arteries, arterioles, capillaries, venules, veins, venous sinus, and ventricles. The flow through the arteries, veins and CSF compartments are governed by continuity, momentum and distensibility balance equations. Furthermore, unlike the Stevens et al. approach, the Monro-Kellie doctrine of constant cranial volume and the bi-phasic nature of the brain parenchyma are implemented. These features appear to be more consistent with the physiologic and anatomical behavior of the CNS, and follow a modeling philosophy similar to the lumped parameter eye model that is intended to be integrated with the CNS model. However, Linninger’s approach has never been implemented to include hydrostatic gradient and microgravity simulation capabilities. Therefore, we aim at implement this modeling approach for spaceflight simulations and assess its overall applicability to VIIP research. OBJECTIVES: We will present verification and validation test results for both models, as well as head-to-head comparison to explore their strengths and limitations with respect to mathematical implementation and physiological significance for VIIP research. In doing so, we hope to provide some guidance to the HRP research community on how to appropriately leverage lumped parameter models for space biomedical research.

Highway Fuel Consumption Computer Model (Version 1)

DOT National Transportation Integrated Search

1974-04-01

A highway fuel consumption computer model is given. The model allows the computation of fuel consumption of a highway vehicle class as a function of time. The model is of the initial value (in this case initial inventory) and lumped parameter type. P...

Deducing Electronic Unit Internal Response During a Vibration Test Using a Lumped Parameter Modeling Approach

NASA Technical Reports Server (NTRS)

Van Dyke, Michael B.

2014-01-01

During random vibration testing of electronic boxes there is often a desire to know the dynamic response of certain internal printed wiring boards (PWBs) for the purpose of monitoring the response of sensitive hardware or for post-test forensic analysis in support of anomaly investigation. Due to restrictions on internally mounted accelerometers for most flight hardware there is usually no means to empirically observe the internal dynamics of the unit, so one must resort to crude and highly uncertain approximations. One common practice is to apply Miles Equation, which does not account for the coupled response of the board in the chassis, resulting in significant over- or under-prediction. This paper explores the application of simple multiple-degree-of-freedom lumped parameter modeling to predict the coupled random vibration response of the PWBs in their fundamental modes of vibration. A simple tool using this approach could be used during or following a random vibration test to interpret vibration test data from a single external chassis measurement to deduce internal board dynamics by means of a rapid correlation analysis. Such a tool might also be useful in early design stages as a supplemental analysis to a more detailed finite element analysis to quickly prototype and analyze the dynamics of various design iterations. After developing the theoretical basis, a lumped parameter modeling approach is applied to an electronic unit for which both external and internal test vibration response measurements are available for direct comparison. Reasonable correlation of the results demonstrates the potential viability of such an approach. Further development of the preliminary approach presented in this paper will involve correlation with detailed finite element models and additional relevant test data.

Uncertainty quantification in flux balance analysis of spatially lumped and distributed models of neuron-astrocyte metabolism.

PubMed

Calvetti, Daniela; Cheng, Yougan; Somersalo, Erkki

2016-12-01

Identifying feasible steady state solutions of a brain energy metabolism model is an inverse problem that allows infinitely many solutions. The characterization of the non-uniqueness, or the uncertainty quantification of the flux balance analysis, is tantamount to identifying the degrees of freedom of the solution. The degrees of freedom of multi-compartment mathematical models for energy metabolism of a neuron-astrocyte complex may offer a key to understand the different ways in which the energetic needs of the brain are met. In this paper we study the uncertainty in the solution, using techniques of linear algebra to identify the degrees of freedom in a lumped model, and Markov chain Monte Carlo methods in its extension to a spatially distributed case. The interpretation of the degrees of freedom in metabolic terms, more specifically, glucose and oxygen partitioning, is then leveraged to derive constraints on the free parameters to guarantee that the model is energetically feasible. We demonstrate how the model can be used to estimate the stoichiometric energy needs of the cells as well as the household energy based on the measured oxidative cerebral metabolic rate of glucose and glutamate cycling. Moreover, our analysis shows that in the lumped model the net direction of lactate dehydrogenase (LDH) in the cells can be deduced from the glucose partitioning between the compartments. The extension of the lumped model to a spatially distributed multi-compartment setting that includes diffusion fluxes from capillary to tissue increases the number of degrees of freedom, requiring the use of statistical sampling techniques. The analysis of the distributed model reveals that some of the conclusions valid for the spatially lumped model, e.g., concerning the LDH activity and glucose partitioning, may no longer hold.

Rational Solutions and Lump Solutions of the Potential YTSF Equation

NASA Astrophysics Data System (ADS)

Sun, Hong-Qian; Chen, Ai-Hua

2017-07-01

By using of the bilinear form, rational solutions and lump solutions of the potential Yu-Toda-Sasa-Fukuyama (YTSF) equation are derived. Dynamics of the fundamental lump solution, n1-order lump solutions, and N-lump solutions are studied for some special cases. We also find some interaction behaviours of solitary waves and one lump of rational solutions.

Gap Excitations and Series Loads in Microstrip Lines: Equivalent Network Characterization with Application to THz Circuits

NASA Technical Reports Server (NTRS)

Neto, Andrea; Siegel, Peter H.

2001-01-01

At submillimeter wavelengths typical gap discontinuities in microstrip, CPW lines or at antenna terminals, which might contain diodes or active elements, cannot be viewed as simple quasi statically evaluated lumped elements. Planar Schottky diodes at 2.5 THz, for example, have a footprint that is comparable to a wavelength. Thus, apart from modelling the diodes themselves, the connection with their exciting elements (antennas or microstrip) gives rise to parasitics. Full wave or strictly numeric approaches can be used to account for these parasitics but at the expense of generality of the solution and the CPU time of the calculation. In this paper an equivalent network is derived that accurately accounts for large gap discontinuities (with respect to a wavelength) without suffering from the limitations of available numeric techniques.

Effects of angles and offsets in crash simulations of automobiles with light trucks

DOT National Transportation Integrated Search

2001-06-06

Two series of finite element and lumped parameter model vehicle-to-vehicle frontal crash simulations were conducted. The vehicles modeled are the 1994 Chevrolet C-1500 light truck and the 1997 Ford Crown Victoria. The first set of simulations involve...

Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations

PubMed Central

Safaei, Soroush; Blanco, Pablo J.; Müller, Lucas O.; Hellevik, Leif R.; Hunter, Peter J.

2018-01-01

We propose a detailed CellML model of the human cerebral circulation that runs faster than real time on a desktop computer and is designed for use in clinical settings when the speed of response is important. A lumped parameter mathematical model, which is based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, is constructed using a bond graph formulation to ensure mass conservation and energy conservation. The model includes arterial vessels with geometric and anatomical data based on the ADAN circulation model. The peripheral beds are represented by lumped parameter compartments. We compare the hemodynamics predicted by the bond graph formulation of the cerebral circulation with that given by a classical one-dimensional Navier-Stokes model working on top of the whole-body ADAN model. Outputs from the bond graph model, including the pressure and flow signatures and blood volumes, are compared with physiological data. PMID:29551979

Channel flow and trichloroethylene treatment in a partly iron-filled fracture: experimental and model results.

PubMed

Cai, Zuansi; Merly, Corrine; Thomson, Neil R; Wilson, Ryan D; Lerner, David N

2007-08-15

Technical developments have now made it possible to emplace granular zero-valent iron (Fe(0)) in fractured media to create a Fe(0) fracture reactive barrier (Fe(0) FRB) for the treatment of contaminated groundwater. To evaluate this concept, we conducted a laboratory experiment in which trichloroethylene (TCE) contaminated water was flushed through a single uniform fracture created between two sandstone blocks. This fracture was partly filled with what was intended to be a uniform thickness of iron. Partial treatment of TCE by iron demonstrated that the concept of a Fe(0) FRB is practical, but was less than anticipated for an iron layer of uniform thickness. When the experiment was disassembled, evidence of discrete channelised flow was noted and attributed to imperfect placement of the iron. To evaluate the effect of the channel flow, an explicit Channel Model was developed that simplifies this complex flow regime into a conceptualised set of uniform and parallel channels. The mathematical representation of this conceptualisation directly accounts for (i) flow channels and immobile fluid arising from the non-uniform iron placement, (ii) mass transfer from the open fracture to iron and immobile fluid regions, and (iii) degradation in the iron regions. A favourable comparison between laboratory data and the results from the developed mathematical model suggests that the model is capable of representing TCE degradation in fractures with non-uniform iron placement. In order to apply this Channel Model concept to a Fe(0) FRB system, a simplified, or implicit, Lumped Channel Model was developed where the physical and chemical processes in the iron layer and immobile fluid regions are captured by a first-order lumped rate parameter. The performance of this Lumped Channel Model was compared to laboratory data, and benchmarked against the Channel Model. The advantages of the Lumped Channel Model are that the degradation of TCE in the system is represented by a first-order parameter that can be used directly in readily available numerical simulators.

Channel flow and trichloroethylene treatment in a partly iron-filled fracture: Experimental and model results

NASA Astrophysics Data System (ADS)

Cai, Zuansi; Merly, Corrine; Thomson, Neil R.; Wilson, Ryan D.; Lerner, David N.

2007-08-01

Technical developments have now made it possible to emplace granular zero-valent iron (Fe 0) in fractured media to create a Fe 0 fracture reactive barrier (Fe 0 FRB) for the treatment of contaminated groundwater. To evaluate this concept, we conducted a laboratory experiment in which trichloroethylene (TCE) contaminated water was flushed through a single uniform fracture created between two sandstone blocks. This fracture was partly filled with what was intended to be a uniform thickness of iron. Partial treatment of TCE by iron demonstrated that the concept of a Fe 0 FRB is practical, but was less than anticipated for an iron layer of uniform thickness. When the experiment was disassembled, evidence of discrete channelised flow was noted and attributed to imperfect placement of the iron. To evaluate the effect of the channel flow, an explicit Channel Model was developed that simplifies this complex flow regime into a conceptualised set of uniform and parallel channels. The mathematical representation of this conceptualisation directly accounts for (i) flow channels and immobile fluid arising from the non-uniform iron placement, (ii) mass transfer from the open fracture to iron and immobile fluid regions, and (iii) degradation in the iron regions. A favourable comparison between laboratory data and the results from the developed mathematical model suggests that the model is capable of representing TCE degradation in fractures with non-uniform iron placement. In order to apply this Channel Model concept to a Fe 0 FRB system, a simplified, or implicit, Lumped Channel Model was developed where the physical and chemical processes in the iron layer and immobile fluid regions are captured by a first-order lumped rate parameter. The performance of this Lumped Channel Model was compared to laboratory data, and benchmarked against the Channel Model. The advantages of the Lumped Channel Model are that the degradation of TCE in the system is represented by a first-order parameter that can be used directly in readily available numerical simulators.

Eigenvalue computations with the QUAD4 consistent-mass matrix

NASA Technical Reports Server (NTRS)

Butler, Thomas A.

1990-01-01

The NASTRAN user has the option of using either a lumped-mass matrix or a consistent- (coupled-) mass matrix with the QUAD4 shell finite element. At the Sixteenth NASTRAN Users' Colloquium (1988), Melvyn Marcus and associates of the David Taylor Research Center summarized a study comparing the results of the QUAD4 element with results of other NASTRAN shell elements for a cylindrical-shell modal analysis. Results of this study, in which both the lumped-and consistent-mass matrix formulations were used, implied that the consistent-mass matrix yielded poor results. In an effort to further evaluate the consistent-mass matrix, a study was performed using both a cylindrical-shell geometry and a flat-plate geometry. Modal parameters were extracted for several modes for both geometries leading to some significant conclusions. First, there do not appear to be any fundamental errors associated with the consistent-mass matrix. However, its accuracy is quite different for the two different geometries studied. The consistent-mass matrix yields better results for the flat-plate geometry and the lumped-mass matrix seems to be the better choice for cylindrical-shell geometries.

Modeling spray/puddle dissolution processes for deep-ultraviolet acid-hardened resists

NASA Astrophysics Data System (ADS)

Hutchinson, John M.; Das, Siddhartha; Qian, Qi-De; Gaw, Henry T.

1993-10-01

A study of the dissolution behavior of acid-hardened resists (AHR) was undertaken for spray and spray/puddle development processes. The Site Services DSM-100 end-point detection system is used to measure both spray and puddle dissolution data for a commercially available deep-ultraviolet AHR resist, Shipley SNR-248. The DSM allows in situ measurement of dissolution rate on the wafer chuck and hence allows parameter extraction for modeling spray and puddle processes. The dissolution data for spray and puddle processes was collected across a range of exposure dose and postexposure bake temperature. The development recipe was varied to decouple the contribution of the spray and puddle modes to the overall dissolution characteristics. The mechanisms involved in spray versus puddle dissolution and the impact of spray versus puddle dissolution on process performance metrics has been investigated. We used the effective-dose-modeling approach and the measurement capability of the DSM-100 and developed a lumped parameter model for acid-hardened resists that incorporates the effects of exposure, postexposure bake temperature and time, and development condition. The PARMEX photoresist-modeling program is used to determine parameters for the spray and for the puddle process. The lumped parameter AHR model developed showed good agreement with experimental data.

Dynamic modeling, property investigation, and adaptive controller design of serial robotic manipulators modeled with structural compliance

NASA Technical Reports Server (NTRS)

Tesar, Delbert; Tosunoglu, Sabri; Lin, Shyng-Her

1990-01-01

Research results on general serial robotic manipulators modeled with structural compliances are presented. Two compliant manipulator modeling approaches, distributed and lumped parameter models, are used in this study. System dynamic equations for both compliant models are derived by using the first and second order influence coefficients. Also, the properties of compliant manipulator system dynamics are investigated. One of the properties, which is defined as inaccessibility of vibratory modes, is shown to display a distinct character associated with compliant manipulators. This property indicates the impact of robot geometry on the control of structural oscillations. Example studies are provided to illustrate the physical interpretation of inaccessibility of vibratory modes. Two types of controllers are designed for compliant manipulators modeled by either lumped or distributed parameter techniques. In order to maintain the generality of the results, neither linearization is introduced. Example simulations are given to demonstrate the controller performance. The second type controller is also built for general serial robot arms and is adaptive in nature which can estimate uncertain payload parameters on-line and simultaneously maintain trajectory tracking properties. The relation between manipulator motion tracking capability and convergence of parameter estimation properties is discussed through example case studies. The effect of control input update delays on adaptive controller performance is also studied.

Analysis of intra-aortic balloon pump model with ovine myocardial infarction.

PubMed

Abdolrazaghi, Mona; Navidbakhsh, Mahdi; Hassani, Kamran; Rabbani, Shahram; Ahmadi, Hossein

2009-12-01

In this study, we have tried to model the effects of intra-aortic balloon pump (IABP) on myocardial infarction (MI) using the standardized data of MI in sheep which was obtained by ligation of the left anterior descending coronary artery. Mathematical model of whole cardiovascular system was presented in accordance to the arterial tree. The lumped parameter model was primarily obtained for a rigid vessel regarding the vessel diameter. In this study, the proper lumped model of every vessel was obtained by incorporating the rigid vessel lumped model into the capacitance as a compliance of the vessel. Intra-aortic balloon pump was modeled with the hemodynamic parameters of the aorta. It was assumed that balloon pump inflates at the beginning of the diastole and deflates near the beginning of the next systole. During balloon pumping, the vessel diameter variation function counter pulsates sinusoidally with the same period of the cardiac cycle. End systolic pressure and end diastolic pressure decreases along with hemodynamic flow optimized through systemic arteries due to balloon pumping in diastole. It has been shown that the blood flow in subclavian artery increases as well. Moreover, the cardiac work keeps low, which prone to lower oxygen consumption. The results of modeling are in good agreement with IABP documentation. The presented model is a useful tool for studying of the cardiovascular system pathology and the presented modeling data are in good agreement with the experimental ones.

Simulated lumped-parameter system reduced-order adaptive control studies

NASA Technical Reports Server (NTRS)

Johnson, C. R., Jr.; Lawrence, D. A.; Taylor, T.; Malakooti, M. V.

1981-01-01

Two methods of interpreting the misbehavior of reduced order adaptive controllers are discussed. The first method is based on system input-output description and the second is based on state variable description. The implementation of the single input, single output, autoregressive, moving average system is considered.

Bridging the gap between measurements and modelling: a cardiovascular functional avatar.

PubMed

Casas, Belén; Lantz, Jonas; Viola, Federica; Cedersund, Gunnar; Bolger, Ann F; Carlhäll, Carl-Johan; Karlsson, Matts; Ebbers, Tino

2017-07-24

Lumped parameter models of the cardiovascular system have the potential to assist researchers and clinicians to better understand cardiovascular function. The value of such models increases when they are subject specific. However, most approaches to personalize lumped parameter models have thus far required invasive measurements or fall short of being subject specific due to a lack of the necessary clinical data. Here, we propose an approach to personalize parameters in a model of the heart and the systemic circulation using exclusively non-invasive measurements. The personalized model is created using flow data from four-dimensional magnetic resonance imaging and cuff pressure measurements in the brachial artery. We term this personalized model the cardiovascular avatar. In our proof-of-concept study, we evaluated the capability of the avatar to reproduce pressures and flows in a group of eight healthy subjects. Both quantitatively and qualitatively, the model-based results agreed well with the pressure and flow measurements obtained in vivo for each subject. This non-invasive and personalized approach can synthesize medical data into clinically relevant indicators of cardiovascular function, and estimate hemodynamic variables that cannot be assessed directly from clinical measurements.

The welfare gain from replacing the health insurance tax exclusion with lump-sum tax credits.

PubMed

Liu, Liqun; Rettenmaier, Andrew J; Saving, Thomas R

2011-06-01

This paper analyzes the welfare gain from replacing the tax exclusion of employer-provided health insurance with a lump-sum tax credit. It differs from earlier studies in that we look at the welfare cost of health insurance tax exclusion as coming directly from excessive health insurance rather than from overconsumption of medical care and that we account for the labor market effect of the tax exclusion on welfare. Both differences work to produce a smaller tax reform welfare gain. For a set of mid-range parameter values, the welfare gain is about 21% of current health insurance tax expenditures. In addition, government tax expenditures would fall by 38%, and health insurance spending would fall by 77% after the reform.

Uncertainty in a monthly water balance model using the generalized likelihood uncertainty estimation methodology

NASA Astrophysics Data System (ADS)

Rivera, Diego; Rivas, Yessica; Godoy, Alex

2015-02-01

Hydrological models are simplified representations of natural processes and subject to errors. Uncertainty bounds are a commonly used way to assess the impact of an input or model architecture uncertainty in model outputs. Different sets of parameters could have equally robust goodness-of-fit indicators, which is known as Equifinality. We assessed the outputs from a lumped conceptual hydrological model to an agricultural watershed in central Chile under strong interannual variability (coefficient of variability of 25%) by using the Equifinality concept and uncertainty bounds. The simulation period ran from January 1999 to December 2006. Equifinality and uncertainty bounds from GLUE methodology (Generalized Likelihood Uncertainty Estimation) were used to identify parameter sets as potential representations of the system. The aim of this paper is to exploit the use of uncertainty bounds to differentiate behavioural parameter sets in a simple hydrological model. Then, we analyze the presence of equifinality in order to improve the identification of relevant hydrological processes. The water balance model for Chillan River exhibits, at a first stage, equifinality. However, it was possible to narrow the range for the parameters and eventually identify a set of parameters representing the behaviour of the watershed (a behavioural model) in agreement with observational and soft data (calculation of areal precipitation over the watershed using an isohyetal map). The mean width of the uncertainty bound around the predicted runoff for the simulation period decreased from 50 to 20 m3s-1 after fixing the parameter controlling the areal precipitation over the watershed. This decrement is equivalent to decreasing the ratio between simulated and observed discharge from 5.2 to 2.5. Despite the criticisms against the GLUE methodology, such as the lack of statistical formality, it is identified as a useful tool assisting the modeller with the identification of critical parameters.

20 CFR 234.12 - 1937 Act lump-sum death payment.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false 1937 Act lump-sum death payment. 234.12 Section 234.12 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.12 1937 Act lump-sum death payment. (a) The 1937 Act...

20 CFR 234.12 - 1937 Act lump-sum death payment.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false 1937 Act lump-sum death payment. 234.12 Section 234.12 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.12 1937 Act lump-sum death payment. (a) The 1937 Act...

20 CFR 234.12 - 1937 Act lump-sum death payment.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false 1937 Act lump-sum death payment. 234.12 Section 234.12 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.12 1937 Act lump-sum death payment. (a) The 1937 Act...

20 CFR 234.12 - 1937 Act lump-sum death payment.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true 1937 Act lump-sum death payment. 234.12 Section 234.12 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.12 1937 Act lump-sum death payment. (a) The 1937 Act...

20 CFR 234.12 - 1937 Act lump-sum death payment.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true 1937 Act lump-sum death payment. 234.12 Section 234.12 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.12 1937 Act lump-sum death payment. (a) The 1937 Act...

Lump solutions and interaction phenomenon to the third-order nonlinear evolution equation

NASA Astrophysics Data System (ADS)

Kofane, T. C.; Fokou, M.; Mohamadou, A.; Yomba, E.

2017-11-01

In this work, the lump solution and the kink solitary wave solution from the (2 + 1) -dimensional third-order evolution equation, using the Hirota bilinear method are obtained through symbolic computation with Maple. We have assumed that the lump solution is centered at the origin, when t = 0 . By considering a mixing positive quadratic function with exponential function, as well as a mixing positive quadratic function with hyperbolic cosine function, interaction solutions like lump-exponential and lump-hyperbolic cosine are presented. A completely non-elastic interaction between a lump and kink soliton is observed, showing that a lump solution can be swallowed by a kink soliton.

Armpit lump

MedlinePlus

... You will be asked questions about your medical history and symptoms, such as: When did you first notice the lump? Has the lump changed? Are you breastfeeding? Is there anything that makes the lump worse? ...

Devolatilization Characteristics and Kinetic Analysis of Lump Coal from China COREX3000 Under High Temperature

NASA Astrophysics Data System (ADS)

Xu, Runsheng; Zhang, Jianliang; Wang, Guangwei; Zuo, Haibin; Liu, Zhengjian; Jiao, Kexin; Liu, Yanxiang; Li, Kejiang

2016-08-01

A devolatilization study of two lump coals used in China COREX3000 was carried out in a self-developed thermo-gravimetry at four temperature conditions [1173 K, 1273 K, 1373 K, and 1473 K (900 °C, 1000 °C, 1100 °C, and 1200 °C)] under N2. This study reveals that the working temperature has a strong impact on the devolatilization rate of the lump coal: the reaction rate increases with the increasing temperature. However, the temperature has little influence on the maximum mass loss. The conversion rate curve shows that the reaction rate of HY lump coal is higher than KG lump coal. The lump coals were analyzed by XRD, FTIR, and optical microscopy to explore the correlation between devolatilization rate and properties of lump coal. The results show that the higher reaction rate of HY lump coal attributes to its more active maceral components, less aromaticity and orientation degree of the crystallite, and more oxygenated functional groups. The random nucleation and nuclei growth model (RNGM), volume model (VM), and unreacted shrinking core model (URCM) were employed to describe the reaction behavior of lump coal. It was concluded from kinetics analysis that RNGM model was the best model for describing the devolatilization of lump coals. The apparent activation energies of isothermal devolatilization of HY lump coal and KG lump coal are 42.35 and 45.83 kJ/mol, respectively. This study has implications for the characteristics and mechanism modeling of devolatilization of lump coal in COREX gasifier.

Mixed lump-kink and rogue wave-kink solutions for a (3 + 1) -dimensional B-type Kadomtsev-Petviashvili equation in fluid mechanics

NASA Astrophysics Data System (ADS)

Hu, Cong-Cong; Tian, Bo; Wu, Xiao-Yu; Yuan, Yu-Qiang; Du, Zhong

2018-02-01

Under investigation is a (3 + 1) -dimensional B-type Kadomtsev-Petviashvili equation, which describes the weakly dispersive waves in a fluid. Via the Hirota method and symbolic computation, we obtain the mixed lump-kink and mixed rogue wave-kink solutions. Through the mixed lump-kink solutions, we observe three different phenomena between a lump and one kink. For the fusion phenomenon, a lump and a kink are merged with the lump's energy transferring into the kink gradually, until the lump merges into the kink completely. Fission phenomenon displays that a lump separates from a kink. The last phenomenon shows that a lump travels together with a kink with their amplitudes unchanged. In addition, we graphically study the interaction between a rogue wave and a pair of the kinks. It can be observed that the rogue wave arises from one kink and disappears into the other kink. At certain time, the amplitude of the rogue wave reaches the maximum.

Bioimpedance Measurement of Segmental Fluid Volumes and Hemodynamics

NASA Technical Reports Server (NTRS)

Montgomery, Leslie D.; Wu, Yi-Chang; Ku, Yu-Tsuan E.; Gerth, Wayne A.; DeVincenzi, D. (Technical Monitor)

2000-01-01

Bioimpedance has become a useful tool to measure changes in body fluid compartment volumes. An Electrical Impedance Spectroscopic (EIS) system is described that extends the capabilities of conventional fixed frequency impedance plethysmographic (IPG) methods to allow examination of the redistribution of fluids between the intracellular and extracellular compartments of body segments. The combination of EIS and IPG techniques was evaluated in the human calf, thigh, and torso segments of eight healthy men during 90 minutes of six degree head-down tilt (HDT). After 90 minutes HDT the calf and thigh segments significantly (P < 0.05) lost conductive volume (eight and four percent, respectively) while the torso significantly (P < 0.05) gained volume (approximately three percent). Hemodynamic responses calculated from pulsatile IPG data also showed a segmental pattern consistent with vascular fluid loss from the lower extremities and vascular engorgement in the torso. Lumped-parameter equivalent circuit analyses of EIS data for the calf and thigh indicated that the overall volume decreases in these segments arose from reduced extracellular volume that was not completely balanced by increased intracellular volume. The combined use of IPG and EIS techniques enables noninvasive tracking of multi-segment volumetric and hemodynamic responses to environmental and physiological stresses.

Fission and fusion interaction phenomena of mixed lump kink solutions for a generalized (3+1)-dimensional B-type Kadomtsev-Petviashvili equation

NASA Astrophysics Data System (ADS)

Liu, Yaqing; Wen, Xiaoyong

2018-05-01

In this paper, a generalized (3+1)-dimensional B-type Kadomtsev-Petviashvili (gBKP) equation is investigated by using the Hirota’s bilinear method. With the aid of symbolic computation, some new lump, mixed lump kink and periodic lump solutions are derived. Based on the derived solutions, some novel interaction phenomena like the fission and fusion interactions between one lump soliton and one kink soliton, the fission and fusion interactions between one lump soliton and a pair of kink solitons and the interactions between two periodic lump solitons are discussed graphically. Results might be helpful for understanding the propagation of the shallow water wave.

20 CFR 234.11 - 1974 Act lump-sum death payment.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false 1974 Act lump-sum death payment. 234.11... LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.11 1974 Act lump-sum death payment. (a) The total amount... household” as the employee at the time of the employee's death. (Refer to § 234.21 for an explanation of...

20 CFR 234.11 - 1974 Act lump-sum death payment.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true 1974 Act lump-sum death payment. 234.11... LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.11 1974 Act lump-sum death payment. (a) The total amount... household” as the employee at the time of the employee's death. (Refer to § 234.21 for an explanation of...

20 CFR 234.11 - 1974 Act lump-sum death payment.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false 1974 Act lump-sum death payment. 234.11... LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.11 1974 Act lump-sum death payment. (a) The total amount... household” as the employee at the time of the employee's death. (Refer to § 234.21 for an explanation of...

20 CFR 234.11 - 1974 Act lump-sum death payment.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false 1974 Act lump-sum death payment. 234.11... LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.11 1974 Act lump-sum death payment. (a) The total amount... household” as the employee at the time of the employee's death. (Refer to § 234.21 for an explanation of...

20 CFR 234.11 - 1974 Act lump-sum death payment.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true 1974 Act lump-sum death payment. 234.11... LUMP-SUM PAYMENTS Lump-Sum Death Payment § 234.11 1974 Act lump-sum death payment. (a) The total amount... household” as the employee at the time of the employee's death. (Refer to § 234.21 for an explanation of...

Lump and lump-soliton solutions to the (2+1) -dimensional Ito equation

NASA Astrophysics Data System (ADS)

Yang, Jin-Yun; Ma, Wen-Xiu; Qin, Zhenyun

2017-06-01

Based on the Hirota bilinear form of the (2+1) -dimensional Ito equation, one class of lump solutions and two classes of interaction solutions between lumps and line solitons are generated through analysis and symbolic computations with Maple. Analyticity is naturally guaranteed for the presented lump and interaction solutions, and the interaction solutions reduce to lumps (or line solitons) while the hyperbolic-cosine (or the quadratic function) disappears. Three-dimensional plots and contour plots are made for two specific examples of the resulting interaction solutions.

Representing Lumped Markov Chains by Minimal Polynomials over Field GF(q)

NASA Astrophysics Data System (ADS)

Zakharov, V. M.; Shalagin, S. V.; Eminov, B. F.

2018-05-01

A method has been proposed to represent lumped Markov chains by minimal polynomials over a finite field. The accuracy of representing lumped stochastic matrices, the law of lumped Markov chains depends linearly on the minimum degree of polynomials over field GF(q). The method allows constructing the realizations of lumped Markov chains on linear shift registers with a pre-defined “linear complexity”.

Accounting for the influence of vegetation and landscape improves model transferability in a tropical savannah region

NASA Astrophysics Data System (ADS)

Gao, Hongkai; Hrachowitz, Markus; Sriwongsitanon, Nutchanart; Fenicia, Fabrizio; Gharari, Shervan; Savenije, Hubert H. G.

2016-10-01

Understanding which catchment characteristics dominate hydrologic response and how to take them into account remains a challenge in hydrological modeling, particularly in ungauged basins. This is even more so in nontemperate and nonhumid catchments, where—due to the combination of seasonality and the occurrence of dry spells—threshold processes are more prominent in rainfall runoff behavior. An example is the tropical savannah, the second largest climatic zone, characterized by pronounced dry and wet seasons and high evaporative demand. In this study, we investigated the importance of landscape variability on the spatial variability of stream flow in tropical savannah basins. We applied a stepwise modeling approach to 23 subcatchments of the Upper Ping River in Thailand, where gradually more information on landscape was incorporated. The benchmark is represented by a classical lumped model (FLEXL), which does not account for spatial variability. We then tested the effect of accounting for vegetation information within the lumped model (FLEXLM), and subsequently two semidistributed models: one accounting for the spatial variability of topography-based landscape features alone (FLEXT), and another accounting for both topographic features and vegetation (FLEXTM). In cross validation, each model was calibrated on one catchment, and then transferred with its fitted parameters to the remaining catchments. We found that when transferring model parameters in space, the semidistributed models accounting for vegetation and topographic heterogeneity clearly outperformed the lumped model. This suggests that landscape controls a considerable part of the hydrological function and explicit consideration of its heterogeneity can be highly beneficial for prediction in ungauged basins in tropical savannah.

Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction

PubMed Central

Desikan, Radhika

2016-01-01

Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

On the rejection of internal and external disturbances in a wind energy conversion system with direct-driven PMSG.

PubMed

Li, Shengquan; Zhang, Kezhao; Li, Juan; Liu, Chao

2016-03-01

This paper deals with the critical issue in a wind energy conversion system (WECS) based on a direct-driven permanent magnet synchronous generator (PMSG): the rejection of lumped disturbance, including the system uncertainties in the internal dynamics and unknown external forces. To simultaneously track the motor speed in real time and capture the maximum power, a maximum power point tracking strategy is proposed based on active disturbance rejection control (ADRC) theory. In real application, system inertia, drive torque and some other parameters change in a wide range with the variations of disturbances and wind speeds, which substantially degrade the performance of WECS. The ADRC design must incorporate the available model information into an extended state observer (ESO) to compensate the lumped disturbance efficiently. Based on this principle, a model-compensation ADRC is proposed in this paper. Simulation study is conducted to evaluate the performance of the proposed control strategy. It is shown that the effect of lumped disturbance is compensated in a more effective way compared with the traditional ADRC approach. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

OHD/HL - Distributed Model

Science.gov Websites

Sacramento Soil Moisture Accounting Model (SAC-SMA) in a lumped and semi-distributed manner. Before any were derived using a procedure developed by VictorKoren ( Useof Soil Property Data in the Derivation of focused on developing a procedure to derive the SAC-SMAmodel parameters based on soil texture data. It is

Lumped Parameter Models for Predicting Nitrogen Transport in Lower Coastal Plain Watersheds

Treesearch

Devendra M. Amatya; George M. Chescheir; Glen P. Fernandez; R. Wayne Skaggs; F. Birgand; J.W. Gilliam

2003-01-01

hl recent years physically based comprehensive disfributed watershed scale hydrologic/water quality models have been developed and applied 10 evaluate cumulative effects of land arld water management practices on receiving waters, Although fhesc complex physically based models are capable of simulating the impacts ofthese changes in large watersheds, they are often...

Electroacoustic analysis, design, and implementation of a small balanced armature speaker.

PubMed

Bai, Mingsian R; You, Bo-Cheng; Lo, Yi-Yang

2014-11-01

This paper presents a new design and implementation of a balanced armature speaker (BAS), which is composed of permanent magnetic circuits, a moving armature, and a coil. The armature rocks about a pivot with the coil at one end and the permanent magnet on another. A magnetic circuit analysis is conducted for the designed BAS to formulate the force factor, which is required for modeling the coupling between the electrical and mechanical systems. In addition, an electromechanoacoustical analogous circuit is established for the BAS, which bears the same structure as the moving coil loudspeaker, except that the force factor is different. A hybrid model, which combines the lumped parameter model in the electrical and acoustical domains with a finite element model in the mechanical domain, is developed to model the high-frequency response because of the high-order modes of the membrane, the drive rod, and the armature. The electroacoustic analysis is experimentally verified. The results indicate that the sound pressure response that is simulated using the hybrid model is in superior agreement with the measured response to that simulated using the lumped parameter model.

Interaction Solutions for Lump-line Solitons and Lump-kink Waves of the Dimensionally Reduced Generalised KP Equation

NASA Astrophysics Data System (ADS)

Ahmed, Iftikhar

2017-09-01

In this work, we investigate dimensionally reduced generalised Kadomtsev-Petviashvili equation, which can describe many nonlinear phenomena in fluid dynamics. Based on the bilinear formalism, direct Maple symbolic computations are used with an ansätz function to construct three classes of interaction solutions between lump and line solitons. Furthermore, the dynamics of interaction phenomena is explained with 3D plots and 2D contour plots. For the first class of interaction solutions, lump appeared at t=0, and there was a normal interaction between lump and line solitons at t=1, 2, 5, and 10. For the second class of interaction solutions, lump appeared from one side of line soliton at t=0, but it started moving downward at t=1, 2, and 5. Finally, at t=10, this lump was completely swallowed by other side. By contrast, for the third class of interaction solutions, lump appeared from one side of line soliton at t=0, but it started moving upward at t=1, 2, and 5. Finally, at t=10, this lump was completely swallowed by other side. Furthermore, interaction solutions between lump solutions and kink wave are also investigated. These results might be helpful to understand the propagation processes for nonlinear waves in fluid mechanics.

A model for flexi-bar to evaluate intervertebral disc and muscle forces in exercises.

PubMed

Abdollahi, Masoud; Nikkhoo, Mohammad; Ashouri, Sajad; Asghari, Mohsen; Parnianpour, Mohamad; Khalaf, Kinda

2016-10-01

This study developed and validated a lumped parameter model for the FLEXI-BAR, a popular training instrument that provides vibration stimulation. The model which can be used in conjunction with musculoskeletal-modeling software for quantitative biomechanical analyses, consists of 3 rigid segments, 2 torsional springs, and 2 torsional dashpots. Two different sets of experiments were conducted to determine the model's key parameters including the stiffness of the springs and the damping ratio of the dashpots. In the first set of experiments, the free vibration of the FLEXI-BAR with an initial displacement at its end was considered, while in the second set, forced oscillations of the bar were studied. The properties of the mechanical elements in the lumped parameter model were derived utilizing a non-linear optimization algorithm which minimized the difference between the model's prediction and the experimental data. The results showed that the model is valid (8% error) and can be used for simulating exercises with the FLEXI-BAR for excitations in the range of the natural frequency. The model was then validated in combination with AnyBody musculoskeletal modeling software, where various lumbar disc, spinal muscles and hand muscles forces were determined during different FLEXI-BAR exercise simulations. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

A physics-based fractional order model and state of energy estimation for lithium ion batteries. Part I: Model development and observability analysis

NASA Astrophysics Data System (ADS)

Li, Xiaoyu; Fan, Guodong; Pan, Ke; Wei, Guo; Zhu, Chunbo; Rizzoni, Giorgio; Canova, Marcello

2017-11-01

The design of a lumped parameter battery model preserving physical meaning is especially desired by the automotive researchers and engineers due to the strong demand for battery system control, estimation, diagnosis and prognostics. In light of this, a novel simplified fractional order electrochemical model is developed for electric vehicle (EV) applications in this paper. In the model, a general fractional order transfer function is designed for the solid phase lithium ion diffusion approximation. The dynamic characteristics of the electrolyte concentration overpotential are approximated by a first-order resistance-capacitor transfer function in the electrolyte phase. The Ohmic resistances and electrochemical reaction kinetics resistance are simplified to a lumped Ohmic resistance parameter. Overall, the number of model parameters is reduced from 30 to 9, yet the accuracy of the model is still guaranteed. In order to address the dynamics of phase-change phenomenon in the active particle during charging and discharging, variable solid-state diffusivity is taken into consideration in the model. Also, the observability of the model is analyzed on two types of lithium ion batteries subsequently. Results show the fractional order model with variable solid-state diffusivity agrees very well with experimental data at various current input conditions and is suitable for electric vehicle applications.

Predicting nitrate discharge dynamics in mesoscale catchments using the lumped StreamGEM model and Bayesian parameter inference

NASA Astrophysics Data System (ADS)

Woodward, Simon James Roy; Wöhling, Thomas; Rode, Michael; Stenger, Roland

2017-09-01

The common practice of infrequent (e.g., monthly) stream water quality sampling for state of the environment monitoring may, when combined with high resolution stream flow data, provide sufficient information to accurately characterise the dominant nutrient transfer pathways and predict annual catchment yields. In the proposed approach, we use the spatially lumped catchment model StreamGEM to predict daily stream flow and nitrate concentration (mg L-1 NO3-N) in four contrasting mesoscale headwater catchments based on four years of daily rainfall, potential evapotranspiration, and stream flow measurements, and monthly or daily nitrate concentrations. Posterior model parameter distributions were estimated using the Markov Chain Monte Carlo sampling code DREAMZS and a log-likelihood function assuming heteroscedastic, t-distributed residuals. Despite high uncertainty in some model parameters, the flow and nitrate calibration data was well reproduced across all catchments (Nash-Sutcliffe efficiency against Log transformed data, NSL, in the range 0.62-0.83 for daily flow and 0.17-0.88 for nitrate concentration). The slight increase in the size of the residuals for a separate validation period was considered acceptable (NSL in the range 0.60-0.89 for daily flow and 0.10-0.74 for nitrate concentration, excluding one data set with limited validation data). Proportions of flow and nitrate discharge attributed to near-surface, fast seasonal groundwater and slow deeper groundwater were consistent with expectations based on catchment geology. The results for the Weida Stream in Thuringia, Germany, using monthly as opposed to daily nitrate data were, for all intents and purposes, identical, suggesting that four years of monthly nitrate sampling provides sufficient information for calibration of the StreamGEM model and prediction of catchment dynamics. This study highlights the remarkable effectiveness of process based, spatially lumped modelling with commonly available monthly stream sample data, to elucidate high resolution catchment function, when appropriate calibration methods are used that correctly handle the inherent uncertainties.

Mechanical Fluidity of Fully Suspended Biological Cells

PubMed Central

Maloney, John M.; Lehnhardt, Eric; Long, Alexandra F.; Van Vliet, Krystyn J.

2013-01-01

Mechanical characteristics of single biological cells are used to identify and possibly leverage interesting differences among cells or cell populations. Fluidity—hysteresivity normalized to the extremes of an elastic solid or a viscous liquid—can be extracted from, and compared among, multiple rheological measurements of cells: creep compliance versus time, complex modulus versus frequency, and phase lag versus frequency. With multiple strategies available for acquisition of this nondimensional property, fluidity may serve as a useful and robust parameter for distinguishing cell populations, and for understanding the physical origins of deformability in soft matter. Here, for three disparate eukaryotic cell types deformed in the suspended state via optical stretching, we examine the dependence of fluidity on chemical and environmental influences at a timescale of ∼1 s. We find that fluidity estimates are consistent in the time and frequency domains under a structural damping (power-law or fractional-derivative) model, but not under an equivalent-complexity, lumped-component (spring-dashpot) model; the latter predicts spurious time constants. Although fluidity is suppressed by chemical cross-linking, we find that ATP depletion in the cell does not measurably alter the parameter, and we thus conclude that active ATP-driven events are not a crucial enabler of fluidity during linear viscoelastic deformation of a suspended cell. Finally, by using the capacity of optical stretching to produce near-instantaneous increases in cell temperature, we establish that fluidity increases with temperature—now measured in a fully suspended, sortable cell without the complicating factor of cell-substratum adhesion. PMID:24138852

Application of a high-energy-density permanent magnet material in underwater systems

NASA Astrophysics Data System (ADS)

Cho, C. P.; Egan, C.; Krol, W. P.

1996-06-01

This paper addresses the application of high-energy-density permanent magnet (PM) technology to (1) the brushless, axial-field PM motor and (2) the integrated electric motor/pump system for under-water applications. Finite-element analysis and lumped parameter magnetic circuit analysis were used to calculate motor parameters and performance characteristics and to conduct tradeoff studies. Compact, efficient, reliable, and quiet underwater systems are attainable with the development of high-energy-density PM material, power electronic devices, and power integrated-circuit technology.

Bone-conduction circuit model for chinchilla part I: Defining parameters by fitting to air-conduction data

NASA Astrophysics Data System (ADS)

Bowers, Peter; Rosowski, John J.

2018-05-01

An air-conduction circuit model that will serve as the basis for a model of bone-conduction hearing is developed for chinchilla. The lumped-element model is based on the classic Zwislocki model of the human middle ear. Model parameters are fit to various measurements of chinchilla middle-ear transfer functions and impedances. The model is in agreement with studies of the effects of middle-ear cavity holes in experiments that require access to the middle-ear air space.

Large Signal Modeling and Analysis of the GaAs MESFET.

DTIC Science & Technology

1986-07-09

various dimensions and physical parameters. A powerful computer aided design system can be developed by automating the circuit element and parameter...circuit model of the GaAs MESFET to aid in the designs of microwave MESFET circuits. The circuit elements of this model are obtained either directly...34. -. ’ Abstract The purpose of this work is to develop a large signal signal lumped circuit model of the GaAs MESFET to aid In the designs of microwave MESFET

Identification of quasi-steady compressor characteristics from transient data

NASA Technical Reports Server (NTRS)

Nunes, K. B.; Rock, S. M.

1984-01-01

The principal goal was to demonstrate that nonlinear compressor map parameters, which govern an in-stall response, can be identified from test data using parameter identification techniques. The tasks included developing and then applying an identification procedure to data generated by NASA LeRC on a hybrid computer. Two levels of model detail were employed. First was a lumped compressor rig model; second was a simplified turbofan model. The main outputs are the tools and procedures generated to accomplish the identification.

Lumped Parameter experiments for Single Mode Fiber Laser Cutting of Thin Stainless Steel Plate

NASA Astrophysics Data System (ADS)

Lai, Shengying; Jia, Ye; Han, Bing; Wang, Jun; Liu, Zongkai; Ni, Xiaowu; Shen, Zhonghua; Lu, Jian

2017-06-01

The present work reports the parameters on laser cutting stainless steel including workpiece thickness, cutting speed, defocus length and assisting gas pressure. The cutting kerf width, dross attachment and cut edge squareness deviation are examined to provide information on cutting quality. The results show that with the increasing thickness, the cutting speed decrease rate is about 27%. The optimal ranges of cutting speed, defocus length and gas pressure are obtained with maximum quality. The first section in your paper

42 CFR 411.46 - Lump-sum payments.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 2 2010-10-01 2010-10-01 false Lump-sum payments. 411.46 Section 411.46 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM... Covered Under Workers' Compensation § 411.46 Lump-sum payments. (a) Lump-sum commutation of future...

20 CFR 225.26 - Residual Lump-Sum PIA.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., except that social security earnings are not used to compute the RLS PIA. ... INSURANCE AMOUNT DETERMINATIONS PIA's Used in Computing Survivor Annuities and the Amount of the Residual Lump-Sum Payable § 225.26 Residual Lump-Sum PIA. The Residual Lump-Sum PIA (RLS PIA) is used to compute...

QUANTIFICATION AND INTERPRETATION OF TOTAL PETROLEUM HYDROCARBONS IN SEDIMENT SAMPLES BY A GC/MS METHOD AND COMPARISON WITH EPA 418.1 AND A RAPID FIELD METHOD

EPA Science Inventory

ABSTRACT: Total Petroleum hydrocarbons (TPH) as a lumped parameter can be easily and rapidly measured or monitored. Despite interpretational problems, it has become an accepted regulatory benchmark used widely to evaluate the extent of petroleum product contamination. Three cu...

Modeling of the Near Field Coupling Between an External Loop and an Implantable Spiral Chip Antennas in Biosensor Systems

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Miranda, Felix A.

2006-01-01

In this paper, the near field coupling between an external hand-held loop antenna and an implantable miniature (1x1 mm) printed square spiral chip antenna used in bio-MEMS sensors for contact-less powering and RF telemetry is investigated. The loop and the spiral are inductively coupled and effectively form a transformer. The numerical results include the quasi-stationary magnetic field pattern of the implanted antenna, near zone wave impedance as a function of the radial distance and the values of the lumped elements in the equivalent circuit model for the transformer.

Applications of SPICE for modeling miniaturized biomedical sensor systems

NASA Technical Reports Server (NTRS)

Mundt, C. W.; Nagle, H. T.

2000-01-01

This paper proposes a model for a miniaturized signal conditioning system for biopotential and ion-selective electrode arrays. The system consists of three main components: sensors, interconnections, and signal conditioning chip. The model for this system is based on SPICE. Transmission-line based equivalent circuits are used to represent the sensors, lumped resistance-capacitance circuits describe the interconnections, and a model for the signal conditioning chip is extracted from its layout. A system for measurements of biopotentials and ionic activities can be miniaturized and optimized for cardiovascular applications based on the development of an integrated SPICE system model of its electrochemical, interconnection, and electronic components.

Excimer laser annealing for low-voltage power MOSFET

NASA Astrophysics Data System (ADS)

Chen, Yi; Okada, Tatsuya; Noguchi, Takashi; Mazzamuto, Fulvio; Huet, Karim

2016-08-01

Excimer laser annealing of lumped beam was performed to form the P-base junction for high-performance low-voltage-power MOSFET. An equivalent shallow-junction structure for the P-base junction with a uniform impurity distribution is realized by adopting excimer laser annealing (ELA). The impurity distribution in the P-base junction can be controlled precisely by the irradiated pulse energy density and the number of shots of excimer laser. High impurity activation for the shallow junction has been confirmed in the melted phase. The application of the laser annealing technology in the fabrication process of a practical low-voltage trench gate MOSFET was also examined.

28 CFR 523.16 - Lump sum awards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... TRANSFER COMPUTATION OF SENTENCE Extra Good Time § 523.16 Lump sum awards. Any staff member may recommend to the Warden the approval of an inmate for a lump sum award of extra good time. Such recommendations... make lump sum awards of extra good time not to exceed thirty days. If the recommendation is for an...

28 CFR 523.16 - Lump sum awards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... TRANSFER COMPUTATION OF SENTENCE Extra Good Time § 523.16 Lump sum awards. Any staff member may recommend to the Warden the approval of an inmate for a lump sum award of extra good time. Such recommendations... make lump sum awards of extra good time not to exceed thirty days. If the recommendation is for an...

28 CFR 523.16 - Lump sum awards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... TRANSFER COMPUTATION OF SENTENCE Extra Good Time § 523.16 Lump sum awards. Any staff member may recommend to the Warden the approval of an inmate for a lump sum award of extra good time. Such recommendations... make lump sum awards of extra good time not to exceed thirty days. If the recommendation is for an...

28 CFR 523.16 - Lump sum awards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... TRANSFER COMPUTATION OF SENTENCE Extra Good Time § 523.16 Lump sum awards. Any staff member may recommend to the Warden the approval of an inmate for a lump sum award of extra good time. Such recommendations... make lump sum awards of extra good time not to exceed thirty days. If the recommendation is for an...

28 CFR 523.16 - Lump sum awards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... TRANSFER COMPUTATION OF SENTENCE Extra Good Time § 523.16 Lump sum awards. Any staff member may recommend to the Warden the approval of an inmate for a lump sum award of extra good time. Such recommendations... make lump sum awards of extra good time not to exceed thirty days. If the recommendation is for an...

Parameter sensitivity analysis of a lumped-parameter model of a chain of lymphangions in series.

PubMed

Jamalian, Samira; Bertram, Christopher D; Richardson, William J; Moore, James E

2013-12-01

Any disruption of the lymphatic system due to trauma or injury can lead to edema. There is no effective cure for lymphedema, partly because predictive knowledge of lymphatic system reactions to interventions is lacking. A well-developed model of the system could greatly improve our understanding of its function. Lymphangions, defined as the vessel segment between two valves, are the individual pumping units. Based on our previous lumped-parameter model of a chain of lymphangions, this study aimed to identify the parameters that affect the system output the most using a sensitivity analysis. The system was highly sensitive to minimum valve resistance, such that variations in this parameter caused an order-of-magnitude change in time-average flow rate for certain values of imposed pressure difference. Average flow rate doubled when contraction frequency was increased within its physiological range. Optimum lymphangion length was found to be some 13-14.5 diameters. A peak of time-average flow rate occurred when transmural pressure was such that the pressure-diameter loop for active contractions was centered near maximum passive vessel compliance. Increasing the number of lymphangions in the chain improved the pumping in the presence of larger adverse pressure differences. For a given pressure difference, the optimal number of lymphangions increased with the total vessel length. These results indicate that further experiments to estimate valve resistance more accurately are necessary. The existence of an optimal value of transmural pressure may provide additional guidelines for increasing pumping in areas affected by edema.

Modeling the human body/seat system in a vibration environment.

PubMed

Rosen, Jacob; Arcan, Mircea

2003-04-01

The vibration environment is a common man-made artificial surrounding with which humans have a limited tolerance to cope due to their body dynamics. This research studied the dynamic characteristics of a seated human body/seat system in a vibration environment. The main result is a multi degrees of freedom lumped parameter model that synthesizes two basic dynamics: (i) global human dynamics, the apparent mass phenomenon, including a systematic set of the model parameters for simulating various conditions like body posture, backrest, footrest, muscle tension, and vibration directions, and (ii) the local human dynamics, represented by the human pelvis/vibrating seat contact, using a cushioning interface. The model and its selected parameters successfully described the main effects of the apparent mass phenomenon compared to experimental data documented in the literature. The model provided an analytical tool for human body dynamics research. It also enabled a primary tool for seat and cushioning design. The model was further used to develop design guidelines for a composite cushion using the principle of quasi-uniform body/seat contact force distribution. In terms of evenly distributing the contact forces, the best result for the different materials and cushion geometries simulated in the current study was achieved using a two layer shaped geometry cushion built from three materials. Combining the geometry and the mechanical characteristics of a structure under large deformation into a lumped parameter model enables successful analysis of the human/seat interface system and provides practical results for body protection in dynamic environment.

Complex capacitance in the representation of modulus of the lithium niobate crystals

NASA Astrophysics Data System (ADS)

Alim, Mohammad A.; Batra, A. K.; Bhattacharjee, Sudip; Aggarwal, M. D.

2011-03-01

The lithium niobate (LiNbO 3 or LN) single crystal is grown in-house. The ac small-signal electrical characterization is conducted over a temperature range 35 ≤T≤150 °C as a function of measurement frequency (10 ≤f≤10 6 Hz). Meaningful observation is noted only in a narrow temperature range 59 ≤T≤73 °C. These electrical data when analyzed via complex plane formalisms revealed single semicircular relaxation both in the complex capacitance ( C*) and in the modulus ( M*) planes. The physical meaning of this kind of observation is obtained on identifying the relaxation type, and then incorporating respective equivalent circuit model. The simplistic non-blocking nature of the equivalent circuit model obtained via M*-plane is established as the lumped relaxation is identified in the C*-plane. The feature of the eventual equivalent circuit model allows non-blocking aspect for the LN crystal attributing to the presence of the operative dc conduction process. Identification of this leakage dc conduction via C*-plane is portrayed in the M*-plane where the blocking nature is removed. The interacting interpretation between these two complex planes is successfully presented.

Lump waves and breather waves for a (3+1)-dimensional generalized Kadomtsev-Petviashvili Benjamin-Bona-Mahony equation for an offshore structure

NASA Astrophysics Data System (ADS)

Yin, Ying; Tian, Bo; Wu, Xiao-Yu; Yin, Hui-Min; Zhang, Chen-Rong

2018-04-01

In this paper, we investigate a (3+1)-dimensional generalized Kadomtsev-Petviashvili Benjamin-Bona-Mahony equation, which describes the fluid flow in the case of an offshore structure. By virtue of the Hirota method and symbolic computation, bilinear forms, the lump-wave and breather-wave solutions are derived. Propagation characteristics and interaction of lump waves and breather waves are graphically discussed. Amplitudes and locations of the lump waves, amplitudes and periods of the breather waves all vary with the wavelengths in the three spatial directions, ratio of the wave amplitude to the depth of water, or product of the depth of water and the relative wavelength along the main direction of propagation. Of the interactions between the lump waves and solitons, there exist two different cases: (i) the energy is transferred from the lump wave to the soliton; (ii) the energy is transferred from the soliton to the lump wave.

Sherwood correlation for dissolution of pooled NAPL in porous media

NASA Astrophysics Data System (ADS)

Aydin Sarikurt, Derya; Gokdemir, Cagri; Copty, Nadim K.

2017-11-01

The rate of interphase mass transfer from non-aqueous phase liquids (NAPLs) entrapped in the subsurface into the surrounding mobile aqueous phase is commonly expressed in terms of Sherwood (Sh) correlations that are expressed as a function of flow and porous media properties. Because of the lack of precise methods for the estimation of the interfacial area separating the NAPL and aqueous phases, most studies have opted to use modified Sherwood expressions that lump the interfacial area into the interphase mass transfer coefficient. To date, there are only two studies in the literature that have developed non-lumped Sherwood correlations; however, these correlations have undergone limited validation. In this paper controlled dissolution experiments from pooled NAPL were conducted. The immobile NAPL mass is placed at the bottom of a flow cell filled with porous media with water flowing horizontally on top. Effluent aqueous phase concentrations were measured for a wide range of aqueous phase velocities and for two different porous media. To interpret the experimental results, a two-dimensional pore network model of the NAPL dissolution kinetics and aqueous phase transport was developed. The observed effluent concentrations were then used to compute best-fit mass transfer coefficients. Comparison of the effluent concentrations computed with the two-dimensional pore network model to those estimated with one-dimensional analytical solutions indicates that the analytical model which ignores the transport in the lateral direction can lead to under-estimation of the mass transfer coefficient. Based on system parameters and the estimated mass transfer coefficients, non-lumped Sherwood correlations were developed and compared to previously published data. The developed correlations, which are a significant improvement over currently available correlations that are associated with large uncertainties, can be incorporated into future modeling studies requiring non-lumped Sh expressions.

Testicle lump

MedlinePlus

... A testicle lump is swelling or a growth (mass) in one or both testicles. Considerations A testicle ... ages. Causes Possible causes of a painful scrotal mass include: A cyst-like lump in the scrotum ...

Experimental Uncertainty Associated with Traveling Wave Excitation

DTIC Science & Technology

2014-09-15

20 2.9 Schematic of the Lumped Model [6] . . . . . . . . . . . . . . . . . . . . . . . 21 2.10 Multiple Coupled Pendulum [7...model to describe the physical system, the authors chose to employ a coupled pendulum model to represent a rotor. This system is shown in Figure 2.10...System mistuning is introduced by altering pendulum lengths. All other system parameters are equal. A linear viscous proportional damping force is

Application of a DRAINMOD-based watershed model to a lower coastal plain watershed

Treesearch

Glenn P. Fernandez; George M. Chescheir; R. Wayne Skaggs; Devendra M. Amatya

2003-01-01

This is a case study for applying DRAINMOD-GIS, a DRAINMOD based lumped parameter watershed model to Chicod Creek, a 11300 ha coastal plain watershed in North Carolina which is not intensively instrumented or documented. The study utilized the current database of land-use, topography, stream network, soil, and weather data available to the State and Federal agencies....

A simplified lumped model for the optimization of post-buckled beam architecture wideband generator

NASA Astrophysics Data System (ADS)

Liu, Weiqun; Formosa, Fabien; Badel, Adrien; Hu, Guangdi

2017-11-01

Buckled beams structures are a classical kind of bistable energy harvesters which attract more and more interests because of their capability to scavenge energy over a large frequency band in comparison with linear generator. The usual modeling approach uses the Galerkin mode discretization method with relatively high complexity, while the simplification with a single-mode solution lacks accuracy. It stems on the optimization of the energy potential features to finally define the physical and geometrical parameters. Therefore, in this paper, a simple lumped model is proposed with explicit relationship between the potential shape and parameters to allow efficient design of bistable beams based generator. The accuracy of the approximation model is studied with the effectiveness of application analyzed. Moreover, an important fact, that the bending stiffness has little influence on the potential shape with low buckling level and the sectional area determined, is found. This feature extends the applicable range of the model by utilizing the design of high moment of inertia. Numerical investigations demonstrate that the proposed model is a simple and reliable tool for design. An optimization example of using the proposed model is demonstrated with satisfactory performance.

Hydrologic relations between lakes and aquifer in a recharge area near Orlando, Florida

USGS Publications Warehouse

Lichtler, William F.; Hughes, G.H.; Pfischner, F.L.

1976-01-01

The three lakes investigated in Orange County, Florida, gain water from adjoining water-table aquifer and lose water to Floridan aquifer by downward leakage. Net seepage (net exchange of water between lake and aquifers) can be estimated by equation S = AX + BY, where S is net seepage, X represents hydraulic gradient between lake and water-table aquifer, A is lumped parameter representing effect of hydraulic conductivity and cross-sectional area of materials in flow section of water-table aquifer, Y is head difference between lake level and potentiometric surface of Floridan aquifer, and B is lumped parameter representing effect of hydraulic conductivity, area, and thickness of materials between lake bottom and Floridan aquifer. If values of S, X, and Y are available for two contrasting water-level conditions, coefficients A and B are determinable by solution of two simultaneous equations. If the relation between lake and ground-water level is the same on all sides of the lake--with regard to each aquifer--and if X and Y are truly representative of these relations, then X and Y terms of equation provide valid estimates of inflow to lake from water-table aquifer and outflow from lake to Floridan aquifer. (Woodard-USGS)

TURTLE with MAD input (Trace Unlimited Rays Through Lumped Elements) -- A computer program for simulating charged particle beam transport systems and DECAY TURTLE including decay calculations

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

Carey, D.C.

1999-12-09

TURTLE is a computer program useful for determining many characteristics of a particle beam once an initial design has been achieved, Charged particle beams are usually designed by adjusting various beam line parameters to obtain desired values of certain elements of a transfer or beam matrix. Such beam line parameters may describe certain magnetic fields and their gradients, lengths and shapes of magnets, spacings between magnetic elements, or the initial beam accepted into the system. For such purposes one typically employs a matrix multiplication and fitting program such as TRANSPORT. TURTLE is designed to be used after TRANSPORT. For conveniencemore » of the user, the input formats of the two programs have been made compatible. The use of TURTLE should be restricted to beams with small phase space. The lumped element approximation, described below, precludes the inclusion of the effect of conventional local geometric aberrations (due to large phase space) or fourth and higher order. A reading of the discussion below will indicate clearly the exact uses and limitations of the approach taken in TURTLE.« less

FORTRAN 4 computer program for calculating critical speeds of rotating shafts

NASA Technical Reports Server (NTRS)

Trivisonno, R. J.

1973-01-01

A FORTRAN 4 computer program, written for the IBM DCS 7094/7044 computer, that calculates the critical speeds of rotating shafts is described. The shaft may include bearings, couplings, extra masses (nonshaft mass), and disks for the gyroscopic effect. Shear deflection is also taken into account, and provision is made in the program for sections of the shaft that are tapered. The boundary conditions at the ends of the shaft can be fixed (deflection and slope equal to zero) or free (shear and moment equal to zero). The fixed end condition enables the program to calculate the natural frequencies of cantilever beams. Instead of using the lumped-parameter method, the program uses continuous integration of the differential equations of beam flexure across different shaft sections. The advantages of this method over the usual lumped-parameter method are less data preparation and better approximation of the distribution of the mass of the shaft. A main feature of the program is the nature of the output. The Calcomp plotter is used to produce a drawing of the shaft with superimposed deflection curves at the critical speeds, together with all pertinent information related to the shaft.

SIMPL: A Simplified Model-Based Program for the Analysis and Visualization of Groundwater Rebound in Abandoned Mines to Prevent Contamination of Water and Soils by Acid Mine Drainage

PubMed Central

Kim, Sung-Min

2018-01-01

Cessation of dewatering following underground mine closure typically results in groundwater rebound, because mine voids and surrounding strata undergo flooding up to the levels of the decant points, such as shafts and drifts. SIMPL (Simplified groundwater program In Mine workings using the Pipe equation and Lumped parameter model), a simplified lumped parameter model-based program for predicting groundwater levels in abandoned mines, is presented herein. The program comprises a simulation engine module, 3D visualization module, and graphical user interface, which aids data processing, analysis, and visualization of results. The 3D viewer facilitates effective visualization of the predicted groundwater level rebound phenomenon together with a topographic map, mine drift, goaf, and geological properties from borehole data. SIMPL is applied to data from the Dongwon coal mine and Dalsung copper mine in Korea, with strong similarities in simulated and observed results. By considering mine workings and interpond connections, SIMPL can thus be used to effectively analyze and visualize groundwater rebound. In addition, the predictions by SIMPL can be utilized to prevent the surrounding environment (water and soil) from being polluted by acid mine drainage. PMID:29747480

Fire Detection Tradeoffs as a Function of Vehicle Parameters

NASA Technical Reports Server (NTRS)

Urban, David L.; Dietrich, Daniel L.; Brooker, John E.; Meyer, Marit E.; Ruff, Gary A.

2016-01-01

Fire survivability depends on the detection of and response to a fire before it has produced an unacceptable environment in the vehicle. This detection time is the result of interplay between the fire burning and growth rates; the vehicle size; the detection system design; the transport time to the detector (controlled by the level of mixing in the vehicle); and the rate at which the life support system filters the atmosphere, potentially removing the detected species or particles. Given the large differences in critical vehicle parameters (volume, mixing rate and filtration rate) the detection approach that works for a large vehicle (e.g. the ISS) may not be the best choice for a smaller crew capsule. This paper examines the impact of vehicle size and environmental control and life support system parameters on the detectability of fires in comparison to the hazard they present. A lumped element model was developed that considers smoke, heat, and toxic product release rates in comparison to mixing and filtration rates in the vehicle. Recent work has quantified the production rate of smoke and several hazardous species from overheated spacecraft polymers. These results are used as the input data set in the lumped element model in combination with the transport behavior of major toxic products released by overheating spacecraft materials to evaluate the necessary alarm thresholds to enable appropriate response to the fire hazard.

Patient-specific biomechanical model of hypoplastic left heart to predict post-operative cardio-circulatory behaviour.

PubMed

Cutrì, Elena; Meoli, Alessio; Dubini, Gabriele; Migliavacca, Francesco; Hsia, Tain-Yen; Pennati, Giancarlo

2017-09-01

Hypoplastic left heart syndrome is a complex congenital heart disease characterised by the underdevelopment of the left ventricle normally treated with a three-stage surgical repair. In this study, a multiscale closed-loop cardio-circulatory model is created to reproduce the pre-operative condition of a patient suffering from such pathology and virtual surgery is performed. Firstly, cardio-circulatory parameters are estimated using a fully closed-loop cardio-circulatory lumped parameter model. Secondly, a 3D standalone FEA model is build up to obtain active and passive ventricular characteristics and unloaded reference state. Lastly, the 3D model of the single ventricle is coupled to the lumped parameter model of the circulation obtaining a multiscale closed-loop pre-operative model. Lacking any information on the fibre orientation, two cases were simulated: (i) fibre distributed as in the physiological right ventricle and (ii) fibre as in the physiological left ventricle. Once the pre-operative condition is satisfactorily simulated for the two cases, virtual surgery is performed. The post-operative results in the two cases highlighted similar hemodynamic behaviour but different local mechanics. This finding suggests that the knowledge of the patient-specific fibre arrangement is important to correctly estimate the single ventricle's working condition and consequently can be valuable to support clinical decision. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

On the feasibility of a transient dynamic design analysis

NASA Astrophysics Data System (ADS)

Cunniff, Patrick F.; Pohland, Robert D.

1993-05-01

The Dynamic Design Analysis Method has been used for the past 30 years as part of the Navy's efforts to shock-harden heavy shipboard equipment. This method which has been validated several times employs normal mode theory and design shock values. This report examines the degree of success that may be achieved by using simple equipment-vehicle models that produce time history responses which are equivalent to the responses that would be achieved using spectral design values employed by the Dynamic Design Analysis Method. These transient models are constructed by attaching the equipment's modal oscillators to the vehicle which is composed of rigid masses and elastic springs. Two methods have been developed for constructing these transient models. Each method generates the parameters of the vehicles so as to approximate the required damaging effects, such that the transient model is excited by an idealized impulse applied to the vehicle mass to which the equipment modal oscillators are attached. The first method called the Direct Modeling Method, is limited to equipment with at most three-degrees of freedom and the vehicle consists of a single lumped mass and spring. The Optimization Modeling Method, which is based on the simplex method for optimization, has been used successfully with a variety of vehicle models and equipment sizes.

A novel sliding mode guidance law without line-of-sight angular rate information accounting for autopilot lag

NASA Astrophysics Data System (ADS)

He, Shaoming; Wang, Jiang; Wang, Wei

2017-12-01

This paper proposes a new composite guidance law to intercept manoeuvring targets without line-of-sight (LOS) angular rate information in the presence of autopilot lag. The presented formulation is obtained via a combination of homogeneous theory and sliding mode control approach. Different from some existing observers, the proposed homogeneous observer can estimate the lumped uncertainty and the LOS angular rate in an integrated manner. To reject the mismatched lumped uncertainty in the integrated guidance and autopilot system, a sliding surface, which consists of the system states and the estimated states, is proposed and a robust guidance law is then synthesised. Stability analysis shows that the LOS angular rate can be stabilised in a small region around zero asymptotically and the upper bound can be lowered by appropriate parameter choice. Numerical simulations with some comparisons are carried out to demonstrate the superiority of the proposed method.

On the stability of lumps and wave collapse in water waves.

PubMed

Akylas, T R; Cho, Yeunwoo

2008-08-13

In the classical water-wave problem, fully localized nonlinear waves of permanent form, commonly referred to as lumps, are possible only if both gravity and surface tension are present. While much attention has been paid to shallow-water lumps, which are generalizations of Korteweg-de Vries solitary waves, the present study is concerned with a distinct class of gravity-capillary lumps recently found on water of finite or infinite depth. In the near linear limit, these lumps resemble locally confined wave packets with envelope and wave crests moving at the same speed, and they can be approximated in terms of a particular steady solution (ground state) of an elliptic equation system of the Benney-Roskes-Davey-Stewartson (BRDS) type, which governs the coupled evolution of the envelope along with the induced mean flow. According to the BRDS equations, however, initial conditions above a certain threshold develop a singularity in finite time, known as wave collapse, due to nonlinear focusing; the ground state, in fact, being exactly at the threshold for collapse suggests that the newly discovered lumps are unstable. In an effort to understand the role of this singularity in the dynamics of lumps, here we consider the fifth-order Kadomtsev-Petviashvili equation, a model for weakly nonlinear gravity-capillary waves on water of finite depth when the Bond number is close to one-third, which also admits lumps of the wave packet type. It is found that an exchange of stability occurs at a certain finite wave steepness, lumps being unstable below but stable above this critical value. As a result, a small-amplitude lump, which is linearly unstable and according to the BRDS equations would be prone to wave collapse, depending on the perturbation, either decays into dispersive waves or evolves into an oscillatory state near a finite-amplitude stable lump.

Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams

USGS Publications Warehouse

Choi, Jungyill; Harvey, Judson W.; Conklin, Martha H.

2000-01-01

The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as subsurface hyporheic zones. However, most investigators use transport models with just a single storage zone in their modeling studies, which assumes that the effects of multiple storage zones can be lumped together. Our study addressed the following question: Can a single‐storage zone model reliably characterize the effects of physical retention and biogeochemical reactions in multiple storage zones? We extended an existing stream transport model with a single storage zone to include a second storage zone. With the extended model we generated 500 data sets representing transport of nonreactive and reactive solutes in stream systems that have two different types of storage zones with variable hydrologic conditions. The one storage zone model was tested by optimizing the lumped storage parameters to achieve a best fit for each of the generated data sets. Multiple storage processes were categorized as possessing I, additive; II, competitive; or III, dominant storage zone characteristics. The classification was based on the goodness of fit of generated data sets, the degree of similarity in mean retention time of the two storage zones, and the relative distributions of exchange flux and storage capacity between the two storage zones. For most cases (>90%) the one storage zone model described either the effect of the sum of multiple storage processes (category I) or the dominant storage process (category III). Failure of the one storage zone model occurred mainly for category II, that is, when one of the storage zones had a much longer mean retention time (ts ratio > 5.0) and when the dominance of storage capacity and exchange flux occurred in different storage zones. We also used the one storage zone model to estimate a “single” lumped rate constant representing the net removal of a solute by biogeochemical reactions in multiple storage zones. For most cases the lumped rate constant that was optimized by one storage zone modeling estimated the flux‐weighted rate constant for multiple storage zones. Our results explain how the relative hydrologic properties of multiple storage zones (retention time, storage capacity, exchange flux, and biogeochemical reaction rate constant) affect the reliability of lumped parameters determined by a one storage zone transport model. We conclude that stream transport models with a single storage compartment will in most cases reliably characterize the dominant physical processes of solute retention and biogeochemical reactions in streams with multiple storage zones.

Taking the mystery out of mathematical model applications to karst aquifers—A primer

USGS Publications Warehouse

Kuniansky, Eve L.

2014-01-01

Advances in mathematical model applications toward the understanding of the complex flow, characterization, and water-supply management issues for karst aquifers have occurred in recent years. Different types of mathematical models can be applied successfully if appropriate information is available and the problems are adequately identified. The mathematical approaches discussed in this paper are divided into three major categories: 1) distributed parameter models, 2) lumped parameter models, and 3) fitting models. The modeling approaches are described conceptually with examples (but without equations) to help non-mathematicians understand the applications.

Distributed parameter system coupled ARMA expansion identification and adaptive parallel IIR filtering - A unified problem statement. [Auto Regressive Moving-Average

NASA Technical Reports Server (NTRS)

Johnson, C. R., Jr.; Balas, M. J.

1980-01-01

A novel interconnection of distributed parameter system (DPS) identification and adaptive filtering is presented, which culminates in a common statement of coupled autoregressive, moving-average expansion or parallel infinite impulse response configuration adaptive parameterization. The common restricted complexity filter objectives are seen as similar to the reduced-order requirements of the DPS expansion description. The interconnection presents the possibility of an exchange of problem formulations and solution approaches not yet easily addressed in the common finite dimensional lumped-parameter system context. It is concluded that the shared problems raised are nevertheless many and difficult.

Quantitative Diagnosis of Continuous-Valued, Stead-State Systems

NASA Technical Reports Server (NTRS)

Rouquette, N.

1995-01-01

Quantitative diagnosis involves numerically estimating the values of unobservable parameters that best explain the observed parameter values. We consider quantitative diagnosis for continuous, lumped- parameter, steady-state physical systems because such models are easy to construct and the diagnosis problem is considerably simpler than that for corresponding dynamic models. To further tackle the difficulties of numerically inverting a simulation model to compute a diagnosis, we propose to decompose a physical system model in terms of feedback loops. This decomposition reduces the dimension of the problem and consequently decreases the diagnosis search space. We illustrate this approach on a model of thermal control system studied in earlier research.

High-frequency resonant-tunneling oscillators

NASA Technical Reports Server (NTRS)

Brown, E. R.; Parker, C. D.; Calawa, A. R.; Manfra, M. J.; Chen, C. L.

1991-01-01

Advances in high-frequency resonant-tunneling-diode (RTD) oscillators are described. Oscillations up to a frequency of 420 GHz have been achieved in the GaAs/AlAs system. Recent results obtained with In0.53Ga0.47As/AlAs and InAs/AlSb RTDs show a greatly increased power density and indicate the potential for fundamental oscillations up to about 1 THz. These results are consistent with a lumped-element equivalent circuit model of the RTD. The model shows that the maximum oscillation frequency of the GaAs/AlAs RTDs is limited primarily by series resistance, and that the power density is limited by low peak-to-valley current ratio.

Electrical model of cold atmospheric plasma gun

NASA Astrophysics Data System (ADS)

Slutsker, Ya. Z.; Semenov, V. E.; Krasik, Ya. E.; Ryzhkov, M. A.; Felsteiner, J.; Binenbaum, Y.; Gil, Z.; Shtrichman, R.; Cohen, J. T.

2017-10-01

We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.

Improvement of modulation bandwidth in electroabsorption-modulated laser by utilizing the resonance property in bonding wire.

PubMed

Kwon, Oh Kee; Han, Young Tak; Baek, Yong Soon; Chung, Yun C

2012-05-21

We present and demonstrate a simple and cost-effective technique for improving the modulation bandwidth of electroabsorption-modulated laser (EML). This technique utilizes the RF resonance caused by the EML chip (i.e., junction capacitance) and bonding wire (i.e, wire inductance). We analyze the effects of the lengths of the bonding wires on the frequency responses of EML by using an equivalent circuit model. To verify this analysis, we package a lumped EML chip on the sub-mount and measure its frequency responses. The results show that, by using the proposed technique, we can increase the modulation bandwidth of EML from ~16 GHz to ~28 GHz.

Lump and rogue waves for the variable-coefficient Kadomtsev-Petviashvili equation in a fluid

NASA Astrophysics Data System (ADS)

Jia, Xiao-Yue; Tian, Bo; Du, Zhong; Sun, Yan; Liu, Lei

2018-04-01

Under investigation in this paper is the variable-coefficient Kadomtsev-Petviashvili equation, which describes the long waves with small amplitude and slow dependence on the transverse coordinate in a single-layer shallow fluid. Employing the bilinear form and symbolic computation, we obtain the lump, mixed lump-stripe soliton and mixed rogue wave-stripe soliton solutions. Discussions indicate that the variable coefficients are related to both the lump soliton’s velocity and amplitude. Mixed lump-stripe soliton solutions display two different properties, fusion and fission. Mixed rogue wave-stripe soliton solutions show that a rogue wave arises from one of the stripe solitons and disappears into the other. When the time approaches 0, rogue wave’s energy reaches the maximum. Interactions between a lump soliton and one-stripe soliton, and between a rogue wave and a pair of stripe solitons, are shown graphically.

A dam-reservoir module for a semi-distributed hydrological model

NASA Astrophysics Data System (ADS)

de Lavenne, Alban; Thirel, Guillaume; Andréassian, Vazken; Perrin, Charles; Ramos, Maria-Helena

2017-04-01

Developing modeling tools that help to assess the spatial distribution of water resources is a key issue to achieve better solutions for the optimal management of water availability among users in a river basin. Streamflow dynamics depends on (i) the spatial variability of rainfall, (ii) the heterogeneity of catchment behavior and response, and (iii) local human regulations (e.g., reservoirs) that store and control surface water. These aspects can be successfully handled by distributed or semi-distributed hydrological models. In this study, we develop a dam-reservoir module within a semi-distributed rainfall-runoff model (de Lavenne et al. 2016). The model runs at the daily time step, and has five parameters for each sub-catchment as well as a streamflow velocity parameter for flow routing. Its structure is based on two stores, one for runoff production and one for routing. The calibration of the model is performed from upstream to downstream sub-catchments, which efficiently uses spatially-distributed streamflow measurements. In a previous study, Payan et al. (2008) described a strategy to implement a dam module within a lumped rainfall-runoff model. Here we propose to adapt this strategy to a semi-distributed hydrological modelling framework. In this way, the specific location of existing reservoirs inside a river basin is explicitly accounted for. Our goal is to develop a tool that can provide answers to the different issues involved in spatial water management in human-influenced contexts and at large modelling scales. The approach is tested for the Seine basin in France. Results are shown for model performance with and without the dam module. Also, a comparison with the lumped GR5J model highlights the improvements obtained in model performance by considering human influences more explicitly, and by facilitating parameter identifiability. This work opens up new perspectives for streamflow naturalization analyses and scenario-based spatial assessment of water resources under global change. References de Lavenne, A.; Thirel, G.; Andréassian, V.; Perrin, C. & Ramos, M.-H. (2016), 'Spatial variability of the parameters of a semi-distributed hydrological model', PIAHS 373, 87-94. Payan, J.-L.; Perrin, C.; Andréassian, V. & Michel, C. (2008), 'How can man-made water reservoirs be accounted for in a lumped rainfall-runoff model?', Water Resour. Res. 44(3), W03420.

Development of an analytical solution for the Budyko watershed parameter in terms of catchment physical features

NASA Astrophysics Data System (ADS)

Reaver, N.; Kaplan, D. A.; Jawitz, J. W.

2017-12-01

The Budyko hypothesis states that a catchment's long-term water and energy balances are dependent on two relatively easy to measure quantities: rainfall depth and potential evaporation. This hypothesis is expressed as a simple function, the Budyko equation, which allows for the prediction of a catchment's actual evapotranspiration and discharge from measured rainfall depth and potential evaporation, data which are widely available. However, the two main analytically derived forms of the Budyko equation contain a single unknown watershed parameter, whose value varies across catchments; variation in this parameter has been used to explain the hydrological behavior of different catchments. The watershed parameter is generally thought of as a lumped quantity that represents the influence of all catchment biophysical features (e.g. soil type and depth, vegetation type, timing of rainfall, etc). Previous work has shown that the parameter is statistically correlated with catchment properties, but an explicit expression has been elusive. While the watershed parameter can be determined empirically by fitting the Budyko equation to measured data in gauged catchments where actual evapotranspiration can be estimated, this limits the utility of the framework for predicting impacts to catchment hydrology due to changing climate and land use. In this study, we developed an analytical solution for the lumped catchment parameter for both forms of the Budyko equation. We combined these solutions with a statistical soil moisture model to obtain analytical solutions for the Budyko equation parameter as a function of measurable catchment physical features, including rooting depth, soil porosity, and soil wilting point. We tested the predictive power of these solutions using the U.S. catchments in the MOPEX database. We also compared the Budyko equation parameter estimates generated from our analytical solutions (i.e. predicted parameters) with those obtained through the calibration of the Budyko equation to discharge data (i.e. empirical parameters), and found good agreement. These results suggest that it is possible to predict the Budyko equation watershed parameter directly from physical features, even for ungauged catchments.

Can a simple lumped parameter model simulate complex transit time distributions? Benchmarking experiments in a virtual watershed.

NASA Astrophysics Data System (ADS)

Wilusz, D. C.; Maxwell, R. M.; Buda, A. R.; Ball, W. P.; Harman, C. J.

2016-12-01

The catchment transit-time distribution (TTD) is the time-varying, probabilistic distribution of water travel times through a watershed. The TTD is increasingly recognized as a useful descriptor of a catchment's flow and transport processes. However, TTDs are temporally complex and cannot be observed directly at watershed scale. Estimates of TTDs depend on available environmental tracers (such as stable water isotopes) and an assumed model whose parameters can be inverted from tracer data. All tracers have limitations though, such as (typically) short periods of observation or non-conservative behavior. As a result, models that faithfully simulate tracer observations may nonetheless yield TTD estimates with significant errors at certain times and water ages, conditioned on the tracer data available and the model structure. Recent advances have shown that time-varying catchment TTDs can be parsimoniously modeled by the lumped parameter rank StorAge Selection (rSAS) model, in which an rSAS function relates the distribution of water ages in outflows to the composition of age-ranked water in storage. Like other TTD models, rSAS is calibrated and evaluated against environmental tracer data, and the relative influence of tracer-dependent and model-dependent error on its TTD estimates is poorly understood. The purpose of this study is to benchmark the ability of different rSAS formulations to simulate TTDs in a complex, synthetic watershed where the lumped model can be calibrated and directly compared to a virtually "true" TTD. This experimental design allows for isolation of model-dependent error from tracer-dependent error. The integrated hydrologic model ParFlow with SLIM-FAST particle tracking code is used to simulate the watershed and its true TTD. To add field intelligence, the ParFlow model is populated with over forty years of hydrometric and physiographic data from the WE-38 subwatershed of the USDA's Mahantango Creek experimental catchment in PA, USA. The results are intended to give practical insight into tradeoffs between rSAS model structure and skill, and define a new performance benchmark to which other transit time models can be compared.

Analysis and Design Considerations of a High-Power Density, Dual Air Gap, Axial-Field Brushless, Permanent Magnet Motor.

NASA Astrophysics Data System (ADS)

Cho, Chahee Peter

1995-01-01

Until recently, brush dc motors have been the dominant drive system because they provide easily controlled motor speed over a wide range, rapid acceleration and deceleration, convenient control of position, and lower product cost. Despite these capabilities, the brush dc motor configuration does not satisfy the design requirements for the U.S. Navy's underwater propulsion applications. Technical advances in rare-earth permanent magnet materials, in high-power semiconductor transistor technology, and in various rotor position-sensing devices have made using brushless permanent magnet motors a viable alternative. This research investigates brushless permanent magnet motor technology, studying the merits of dual-air gap, axial -field, brushless, permanent magnet motor configuration in terms of power density, efficiency, and noise/vibration levels. Because the design objectives for underwater motor applications include high-power density, high-performance, and low-noise/vibration, the traditional, simplified equivalent circuit analysis methods to assist in meeting these goals were inadequate. This study presents the development and verification of detailed finite element analysis (FEA) models and lumped parameter circuit models that can calculate back electromotive force waveforms, inductance, cogging torque, energized torque, and eddy current power losses. It is the first thorough quantification of dual air-gap, axial -field, brushless, permanent magnet motor parameters and performance characteristics. The new methodology introduced in this research not only facilitates the design process of an axial field, brushless, permanent magnet motor but reinforces the idea that the high-power density, high-efficiency, and low-noise/vibration motor is attainable.

Technique for predicting high-frequency stability characteristics of gaseous-propellant combustors

NASA Technical Reports Server (NTRS)

Priem, R. J.; Jefferson, Y. S. Y.

1973-01-01

A technique for predicting the stability characteristics of a gaseous-propellant rocket combustion system is developed based on a model that assumes coupling between the flow through the injector and the oscillating chamber pressure. The theoretical model uses a lumped parameter approach for the flow elements in the injection system plus wave dynamics in the combustion chamber. The injector flow oscillations are coupled to the chamber pressure oscillations with a delay time. Frequency and decay (or growth) rates are calculated for various combustor design and operating parameters to demonstrate the influence of various parameters on stability. Changes in oxidizer design parameters had a much larger influence on stability than a similar change in fuel parameters. A complete description of the computer program used to make these calculations is given in an appendix.

Estimating Groundwater-Age Distributions Contributing to Streams in the Fractured-Rock Terrain of the Upper Potomac River Basin, USA (Invited)

NASA Astrophysics Data System (ADS)

Sanford, W. E.; Fleming, B.; Pope, J.

2013-12-01

Base flow to individual streams has discharging groundwater with ages that vary widely between values of days to centuries or more. This distribution of ages has important repercussions for the response time of a watershed between change in land-use practices and the discharge of contaminants, such as nitrogen, to streams or coastal waterways. Lumped parameter models are frequently used to predict such watershed responses in shallow aquifers, but these usually assume homogeneous hydraulic properties. In the Chesapeake Bay watershed, however, over half of the terrain is underlain by fractured-rock, where heterogeneous hydraulic properties do not fit standard lumped-parameter model assumptions. In order to better understand the response behavior of a regional fractured-rock terrain, we developed a seven-million node, three-dimensional groundwater model of the Upper Potomac River Basin (~24,000 sq. km) using MODFLOW that includes siliciclastic, carbonate, and metamorphic rocks. Inverse modeling was undertaken to estimate regional values of hydraulic conductivity (K) using 200 water-level measurements in wells, and effective porosity using >100 environmental tracer (CFC-113, SF6, 3H, 3He) measurements from wells, springs and the Potomac River at the basin outlet. Results indicate a very strong depth-dependence of K, with values declining by 4-6 orders of magnitude within 100 m of land surface, with the bulk of the transmissivity being focused in the upper 10 m. This depth-dependent behavior has major implications for the watershed response time, as the base flows have ages that range over four orders of magnitude, as opposed to a shallow homogenous aquifer that usually has an equivalent range of less than two orders of magnitude. A tritium record from 1961-1991 in the Potomac River at the basin outflow can be reproduced by the model using advective transport and a single regional porosity value of 2-3 percent. In addition, the fit to the data can be improved at early and late times by assuming fracture porosity (1-2%) dominates transport at shallow (<10 m depth) depths, and matrix porosity (5-20%) dominates at deeper (>10 m) depths. Histograms of base-flow ages for individual subwatersheds in the basin have mean values of decades, but median values on the order of one year. Base-flow age is also predicted to increase substantially in these subwatersheds in the downstream direction.

29 CFR 4050.8 - Automatic lump sum.

Code of Federal Regulations, 2010 CFR

2010-07-01

... present value (determined as of the deemed distribution date under the missing participant lump sum... Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION PLAN TERMINATIONS MISSING PARTICIPANTS § 4050.8 Automatic lump sum. This section applies to a missing participant whose designated benefit was...

VETERANS BENEFITS: Veterans Have Mixed Views on a Lump Sum Disability Payment Option

DTIC Science & Technology

2000-12-01

These advantages and disadvantages generally weigh the benefit of financial flexibility against the risk of financial loss. 8If the lump sum is... BENEFITS Veterans Have Mixed Views on a Lump Sum Disability Payment OptionGAO-01-172 Form SF298 Citation Data Report Date ("DD MON YYYY") 00DEC2000...Report Type N/A Dates Covered (from... to) ("DD MON YYYY") Title and Subtitle VETERANS BENEFITS Veterans Have Mixed Views on a Lump Sum Disability

Hybrid soliton solutions in the (2+1)-dimensional nonlinear Schrödinger equation

NASA Astrophysics Data System (ADS)

Chen, Meidan; Li, Biao

2017-11-01

Rational solutions and hybrid solutions from N-solitons are obtained by using the bilinear method and a long wave limit method. Line rogue waves and lumps in the (2+1)-dimensional nonlinear Schrödinger (NLS) equation are derived from two-solitons. Then from three-solitons, hybrid solutions between kink soliton with breathers, periodic line waves and lumps are derived. Interestingly, after the collision, the breathers are kept invariant, but the amplitudes of the periodic line waves and lumps change greatly. For the four-solitons, the solutions describe as breathers with breathers, line rogue waves or lumps. After the collision, breathers and lumps are kept invariant, but the line rogue wave has a great change.

Management of palpable breast lumps. Consensus guideline for family physicians.

PubMed Central

Heisey, R.; Mahoney, L.; Watson, B.

1999-01-01

OBJECTIVE: To describe an approach to managing women who present with palpable breast lumps. QUALITY OF EVIDENCE: Databases were searched from 1990 to 1998 using the search terms breast lumps, breast diseases, and breast cysts. Bibliographies of the articles obtained were searched for further relevant titles. Most evidence on management of breast cysts was obtained from cohort studies. Evidence on family physicians' approach to managing breast lumps is based on a review of the 1998 Canadian consensus guidelines and a review of a 1998 consensus guideline by 12 University of Toronto surgical oncologists (U of T guidelines). MAIN MESSAGE: Family physicians can manage women presenting with breast lumps if they have skill in breast cyst aspiration. Most breast cysts can be cured in minutes, thus avoiding unwarranted anxiety and eliminating unnecessary additional investigations and referrals. Women presenting with solid lesions should be referred to a surgeon. CONCLUSIONS: Breast cyst aspiration is a simple technique family physicians can use to either cure breast lumps or define appropriate cases for referral. PMID:10463093

Dynamics of lumps and dark-dark solitons in the multi-component long-wave-short-wave resonance interaction system.

PubMed

Rao, Jiguang; Porsezian, Kuppuswamy; He, Jingsong; Kanna, Thambithurai

2018-01-01

General semi-rational solutions of an integrable multi-component (2+1)-dimensional long-wave-short-wave resonance interaction system comprising multiple short waves and a single long wave are obtained by employing the bilinear method. These solutions describe the interactions between various types of solutions, including line rogue waves, lumps, breathers and dark solitons. We only focus on the dynamical behaviours of the interactions between lumps and dark solitons in this paper. Our detailed study reveals two different types of excitation phenomena: fusion and fission. It is shown that the fundamental (simplest) semi-rational solutions can exhibit fission of a dark soliton into a lump and a dark soliton or fusion of one lump and one dark soliton into a dark soliton. The non-fundamental semi-rational solutions are further classified into three subclasses: higher-order, multi- and mixed-type semi-rational solutions. The higher-order semi-rational solutions show the process of annihilation (production) of two or more lumps into (from) one dark soliton. The multi-semi-rational solutions describe N ( N ≥2) lumps annihilating into or producing from N -dark solitons. The mixed-type semi-rational solutions are a hybrid of higher-order semi-rational solutions and multi-semi-rational solutions. For the mixed-type semi-rational solutions, we demonstrate an interesting dynamical behaviour that is characterized by partial suppression or creation of lumps from the dark solitons.

Dynamics of lumps and dark-dark solitons in the multi-component long-wave-short-wave resonance interaction system

NASA Astrophysics Data System (ADS)

Rao, Jiguang; Porsezian, Kuppuswamy; He, Jingsong; Kanna, Thambithurai

2018-01-01

General semi-rational solutions of an integrable multi-component (2+1)-dimensional long-wave-short-wave resonance interaction system comprising multiple short waves and a single long wave are obtained by employing the bilinear method. These solutions describe the interactions between various types of solutions, including line rogue waves, lumps, breathers and dark solitons. We only focus on the dynamical behaviours of the interactions between lumps and dark solitons in this paper. Our detailed study reveals two different types of excitation phenomena: fusion and fission. It is shown that the fundamental (simplest) semi-rational solutions can exhibit fission of a dark soliton into a lump and a dark soliton or fusion of one lump and one dark soliton into a dark soliton. The non-fundamental semi-rational solutions are further classified into three subclasses: higher-order, multi- and mixed-type semi-rational solutions. The higher-order semi-rational solutions show the process of annihilation (production) of two or more lumps into (from) one dark soliton. The multi-semi-rational solutions describe N(N≥2) lumps annihilating into or producing from N-dark solitons. The mixed-type semi-rational solutions are a hybrid of higher-order semi-rational solutions and multi-semi-rational solutions. For the mixed-type semi-rational solutions, we demonstrate an interesting dynamical behaviour that is characterized by partial suppression or creation of lumps from the dark solitons.

Parameter dimensionality reduction of a conceptual model for streamflow prediction in Canadian, snowmelt dominated ungauged basins

NASA Astrophysics Data System (ADS)

Arsenault, Richard; Poissant, Dominique; Brissette, François

2015-11-01

This paper evaluated the effects of parametric reduction of a hydrological model on five regionalization methods and 267 catchments in the province of Quebec, Canada. The Sobol' variance-based sensitivity analysis was used to rank the model parameters by their influence on the model results and sequential parameter fixing was performed. The reduction in parameter correlations improved parameter identifiability, however this improvement was found to be minimal and was not transposed in the regionalization mode. It was shown that 11 of the HSAMI models' 23 parameters could be fixed with little or no loss in regionalization skill. The main conclusions were that (1) the conceptual lumped models used in this study did not represent physical processes sufficiently well to warrant parameter reduction for physics-based regionalization methods for the Canadian basins examined and (2) catchment descriptors did not adequately represent the relevant hydrological processes, namely snow accumulation and melt.

Rapid Quantification of Energy Absorption and Dissipation Metrics for PPE Padding Materials

DTIC Science & Technology

2010-01-22

dampers ,   i.e.,  Hooke’s  Law  springs  and   viscous ...absorbing/dissipating materials. Input forces caused by blast pressures, determined from computational fluid dynamics (CFD) analysis and simulation...simple  lumped-­‐ parameter  elements   –  spring,  k  (energy  storage)   –  damper ,  b  (energy  dissipa/on   Rapid

Directions for computational mechanics in automotive crashworthiness

NASA Technical Reports Server (NTRS)

Bennett, James A.; Khalil, T. B.

1993-01-01

The automotive industry has used computational methods for crashworthiness since the early 1970's. These methods have ranged from simple lumped parameter models to full finite element models. The emergence of the full finite element models in the mid 1980's has significantly altered the research direction. However, there remains a need for both simple, rapid modeling methods and complex detailed methods. Some directions for continuing research are discussed.

Directions for computational mechanics in automotive crashworthiness

NASA Astrophysics Data System (ADS)

Bennett, James A.; Khalil, T. B.

1993-08-01

The automotive industry has used computational methods for crashworthiness since the early 1970's. These methods have ranged from simple lumped parameter models to full finite element models. The emergence of the full finite element models in the mid 1980's has significantly altered the research direction. However, there remains a need for both simple, rapid modeling methods and complex detailed methods. Some directions for continuing research are discussed.

The Prediction of Transducer Element Performance from In-Air Measurements.

DTIC Science & Technology

1982-01-19

33 13. Predicted and Measured Transducer Impedance . . . 35 14. Principle of Operation of Fotonic Sensor . . . . 40 15. Experimental Set-up for...inferred from tests of the assembled element, and cannot account for assembly problems such as misalignment and improper glue joints. Thus, the...the results neither predict nor account for the element variability found in actual practice. Our purpose, then, is to derive the lumped-parameter

Modal analysis of human body vibration model for Indian subjects under sitting posture.

PubMed

Singh, Ishbir; Nigam, S P; Saran, V H

2015-01-01

Need and importance of modelling in human body vibration research studies are well established. The study of biodynamic responses of human beings can be classified into experimental and analytical methods. In the past few decades, plenty of mathematical models have been developed based on the diverse field measurements to describe the biodynamic responses of human beings. In this paper, a complete study on lumped parameter model derived from 50th percentile anthropometric data for a seated 54- kg Indian male subject without backrest support under free un-damped conditions has been carried out considering human body segments to be of ellipsoidal shape. Conventional lumped parameter modelling considers the human body as several rigid masses interconnected by springs and dampers. In this study, concept of mass of interconnecting springs has been incorporated and eigenvalues thus obtained are found to be closer to the values reported in the literature. Results obtained clearly establish decoupling of vertical and fore-and-aft oscillations. The mathematical modelling of human body vibration studies help in validating the experimental investigations for ride comfort of a sitting subject. This study clearly establishes the decoupling of vertical and fore-and-aft vibrations and helps in better understanding of possible human response to single and multi-axial excitations.

Air sparging: Air-water mass transfer coefficients

NASA Astrophysics Data System (ADS)

Braida, Washington J.; Ong, Say Kee

1998-12-01

Experiments investigating the mass transfer of several dissolved volatile organic compounds (VOCs) across the air-water interface were conducted using a single-air- channel air-sparging system. Three different porous media were used in the study. Air velocities ranged from 0.2 cm s-1 to 2.5 cm s-1. The tortuosity factor for each porous medium and the air-water mass transfer coefficients were estimated by fitting experimental data to a one-dimensional diffusion model. The estimated mass transfer coefficients KG ranged from 1.79 × 10-3 cm min-1 to 3.85 × 10-2 cm min-1. The estimated lumped gas phase mass transfer coefficients KGa were found to be directly related to the air diffusivity of the VOC, air velocity, and particle size, and inversely related to the Henry's law constant of the VOCs. Of the four parameters investigated, the parameter that controlled or had a dominant effect on the lumped gas phase mass transfer coefficient was the air diffusivity of the VOC. Two empirical models were developed by correlating the Damkohler and the modified air phase Sherwood numbers with the air phase Peclet number, Henry's law constant, and the reduced mean particle size of porous media. The correlation developed in this study may be used to obtain better predictions of mass transfer fluxes for field conditions.

Laser cutting of various materials: Kerf width size analysis and life cycle assessment of cutting process

NASA Astrophysics Data System (ADS)

Yilbas, Bekir Sami; Shaukat, Mian Mobeen; Ashraf, Farhan

2017-08-01

Laser cutting of various materials including Ti-6Al-4V alloy, steel 304, Inconel 625, and alumina is carried out to assess the kerf width size variation along the cut section. The life cycle assessment is carried out to determine the environmental impact of the laser cutting in terms of the material waste during the cutting process. The kerf width size is formulated and predicted using the lump parameter analysis and it is measured from the experiments. The influence of laser output power and laser cutting speed on the kerf width size variation is analyzed using the analytical tools including scanning electron and optical microscopes. In the experiments, high pressure nitrogen assisting gas is used to prevent oxidation reactions in the cutting section. It is found that the kerf width size predicted from the lump parameter analysis agrees well with the experimental data. The kerf width size variation increases with increasing laser output power. However, this behavior reverses with increasing laser cutting speed. The life cycle assessment reveals that material selection for laser cutting is critical for the environmental protection point of view. Inconel 625 contributes the most to the environmental damages; however, recycling of the waste of the laser cutting reduces this contribution.

23 CFR 140.920 - Lump sum payments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Lump sum payments. 140.920 Section 140.920 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Railroad Work § 140.920 Lump sum payments. Where approved by FHWA, pursuant to 23 CFR 646.216...

23 CFR 140.920 - Lump sum payments.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false Lump sum payments. 140.920 Section 140.920 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Railroad Work § 140.920 Lump sum payments. Where approved by FHWA, pursuant to 23 CFR 646.216...

23 CFR 140.920 - Lump sum payments.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false Lump sum payments. 140.920 Section 140.920 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Railroad Work § 140.920 Lump sum payments. Where approved by FHWA, pursuant to 23 CFR 646.216...

23 CFR 140.920 - Lump sum payments.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false Lump sum payments. 140.920 Section 140.920 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Railroad Work § 140.920 Lump sum payments. Where approved by FHWA, pursuant to 23 CFR 646.216...

20 CFR 222.44 - Other relationship determinations for lump-sum payments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... THE RAILROAD RETIREMENT ACT FAMILY RELATIONSHIPS Relationship as Parent, Grandchild, Brother or Sister § 222.44 Other relationship determinations for lump-sum payments. Other claimants will be considered to... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Other relationship determinations for lump...

29 CFR 4050.9 - Annuity or elective lump sum-living missing participant.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 9 2014-07-01 2014-07-01 false Annuity or elective lump sum-living missing participant... CORPORATION PLAN TERMINATIONS MISSING PARTICIPANTS § 4050.9 Annuity or elective lump sum—living missing participant. This section applies to a missing participant whose designated benefit was determined under...

29 CFR 4050.9 - Annuity or elective lump sum-living missing participant.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 9 2011-07-01 2011-07-01 false Annuity or elective lump sum-living missing participant... CORPORATION PLAN TERMINATIONS MISSING PARTICIPANTS § 4050.9 Annuity or elective lump sum—living missing participant. This section applies to a missing participant whose designated benefit was determined under...

29 CFR 4050.9 - Annuity or elective lump sum-living missing participant.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 9 2013-07-01 2013-07-01 false Annuity or elective lump sum-living missing participant... CORPORATION PLAN TERMINATIONS MISSING PARTICIPANTS § 4050.9 Annuity or elective lump sum—living missing participant. This section applies to a missing participant whose designated benefit was determined under...

29 CFR 4050.9 - Annuity or elective lump sum-living missing participant.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 9 2012-07-01 2012-07-01 false Annuity or elective lump sum-living missing participant... CORPORATION PLAN TERMINATIONS MISSING PARTICIPANTS § 4050.9 Annuity or elective lump sum—living missing participant. This section applies to a missing participant whose designated benefit was determined under...

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

Wight, L.; Zaslawsky, M.

Two approaches for calculating soil structure interaction (SSI) are compared: finite element and lumped mass. Results indicate that the calculations with the lumped mass method are generally conservative compared to those obtained by the finite element method. They also suggest that a closer agreement between the two sets of calculations is possible, depending on the use of frequency-dependent soil springs and dashpots in the lumped mass calculations. There is a total lack of suitable guidelines for implementing the lumped mass method of calculating SSI, which leads to the conclusion that the finite element method is generally superior for calculative purposes.

Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops.

PubMed

Warriner, David R; Brown, Alistair G; Varma, Susheel; Sheridan, Paul J; Lawford, Patricia; Hose, David R; Al-Mohammad, Abdallah; Shi, Yubing

2014-01-01

The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models. A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax). For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

Noise analysis in air-coupled PVDF ultrasonic sensors.

PubMed

Fiorillo, A S

2000-01-01

In this paper we analyze the noise generated in a piezo-polymer based sensor for low frequency ultrasound in air. The sensor includes two curved PVDF transducers for medium and short range applications. A lumped RLC equivalent circuit was derived from the measurement of the transducer's electrical admittance, in air, by taking into account both mechanical and dielectric losses, which we suppose are the major sources of noise in similar devices. The electrical model was used to study and optimize the noise performance of a 61 kHz transducer and to simulate the electrical behavior of the complete transmitter-receiver system. The validity of the overall electrical model with low noise was confirmed after verifying, with Pspice, agreement of the practical and theoretical results.

Equivalent-circuit models for electret-based vibration energy harvesters

NASA Astrophysics Data System (ADS)

Phu Le, Cuong; Halvorsen, Einar

2017-08-01

This paper presents a complete analysis to build a tool for modelling electret-based vibration energy harvesters. The calculational approach includes all possible effects of fringing fields that may have significant impact on output power. The transducer configuration consists of two sets of metal strip electrodes on a top substrate that faces electret strips deposited on a bottom movable substrate functioning as a proof mass. Charge distribution on each metal strip is expressed by series expansion using Chebyshev polynomials multiplied by a reciprocal square-root form. The Galerkin method is then applied to extract all charge induction coefficients. The approach is validated by finite element calculations. From the analytic tool, a variety of connection schemes for power extraction in slot-effect and cross-wafer configurations can be lumped to a standard equivalent circuit with inclusion of parasitic capacitance. Fast calculation of the coefficients is also obtained by a proposed closed-form solution based on leading terms of the series expansions. The achieved analytical result is an important step for further optimisation of the transducer geometry and maximising harvester performance.

An efficient deterministic-probabilistic approach to modeling regional groundwater flow: 2. Application to Owens Valley, California

USGS Publications Warehouse

Guymon, Gary L.; Yen, Chung-Cheng

1990-01-01

The applicability of a deterministic-probabilistic model for predicting water tables in southern Owens Valley, California, is evaluated. The model is based on a two-layer deterministic model that is cascaded with a two-point probability model. To reduce the potentially large number of uncertain variables in the deterministic model, lumping of uncertain variables was evaluated by sensitivity analysis to reduce the total number of uncertain variables to three variables: hydraulic conductivity, storage coefficient or specific yield, and source-sink function. Results demonstrate that lumping of uncertain parameters reduces computational effort while providing sufficient precision for the case studied. Simulated spatial coefficients of variation for water table temporal position in most of the basin is small, which suggests that deterministic models can predict water tables in these areas with good precision. However, in several important areas where pumping occurs or the geology is complex, the simulated spatial coefficients of variation are over estimated by the two-point probability method.

An efficient deterministic-probabilistic approach to modeling regional groundwater flow: 2. Application to Owens Valley, California

NASA Astrophysics Data System (ADS)

Guymon, Gary L.; Yen, Chung-Cheng

1990-07-01

The applicability of a deterministic-probabilistic model for predicting water tables in southern Owens Valley, California, is evaluated. The model is based on a two-layer deterministic model that is cascaded with a two-point probability model. To reduce the potentially large number of uncertain variables in the deterministic model, lumping of uncertain variables was evaluated by sensitivity analysis to reduce the total number of uncertain variables to three variables: hydraulic conductivity, storage coefficient or specific yield, and source-sink function. Results demonstrate that lumping of uncertain parameters reduces computational effort while providing sufficient precision for the case studied. Simulated spatial coefficients of variation for water table temporal position in most of the basin is small, which suggests that deterministic models can predict water tables in these areas with good precision. However, in several important areas where pumping occurs or the geology is complex, the simulated spatial coefficients of variation are over estimated by the two-point probability method.

General high-order breathers and rogue waves in the (3 + 1) -dimensional KP-Boussinesq equation

NASA Astrophysics Data System (ADS)

Sun, Baonan; Wazwaz, Abdul-Majid

2018-11-01

In this work, we investigate the (3 + 1) -dimensional KP-Boussinesq equation, which can be used to describe the nonlinear dynamic behavior in scientific and engineering applications. We derive general high-order soliton solutions by using the Hirota's bilinear method combined with the perturbation expansion technique. We also obtain periodic solutions comprising of high-order breathers, periodic line waves, and mixed solutions consisting of breathers and periodic line waves upon selecting particular parameter constraints of the obtained soliton solutions. Furthermore, smooth rational solutions are generated by taking a long wave limit of the soliton solutions. These smooth rational solutions include high-order rogue waves, high-order lumps, and hybrid solutions consisting of lumps and line rogue waves. To better understand the dynamical behaviors of these solutions, we discuss some illustrative graphical analyses. It is expected that our results can enrich the dynamical behavior of the (3 + 1) -dimensional nonlinear evolution equations of other forms.

Theoretical investigation of dielectric corona pre-ionization TEA nitrogen laser based on transmission line method

NASA Astrophysics Data System (ADS)

Bahrampour, Alireza; Fallah, Robabeh; Ganjovi, Alireza A.; Bahrampour, Abolfazl

2007-07-01

This paper models the dielectric corona pre-ionization, capacitor transfer type of flat-plane transmission line traveling wave transverse excited atmospheric pressure nitrogen laser by a non-linear lumped RLC electric circuit. The flat-plane transmission line and the pre-ionizer dielectric are modeled by a lumped linear RLC and time-dependent non-linear RC circuit, respectively. The main discharge region is considered as a time-dependent non-linear RLC circuit where its resistance value is also depends on the radiated pre-ionization ultra violet (UV) intensity. The UV radiation is radiated by the resistance due to the surface plasma on the pre-ionizer dielectric. The theoretical predictions are in a very good agreement with the experimental observations. The electric circuit equations (including the ionization rate equations), the equations of laser levels population densities and propagation equation of laser intensities, are solved numerically. As a result, the effects of pre-ionizer dielectric parameters on the electrical behavior and output laser intensity are obtained.

Hormones, Women and Breast Cancer

MedlinePlus

... sure that it is benign (not cancer). These tests can include • A mammogram • A breast ultrasound • A sample of cells from the lump (called a fine needle aspirate) • A sample of a piece of tissue from the lump (called a core biopsy) Possible Symptoms of Breast Cancer • A lump • ...

Lumped parameter, isotopic model simulations of closed-basin lake response to drought in the Pacific Northwest and implications for lake sediment oxygen isotope records.

NASA Astrophysics Data System (ADS)

Steinman, B. A.; Rosenmeier, M.; Abbott, M.

2008-12-01

The economy of the Pacific Northwest relies heavily on water resources from the drought-prone Columbia River and its tributaries, as well as the many lakes and reservoirs of the region. Proper management of these water resources requires a thorough understanding of local drought histories that extends well beyond the instrumental record of the twentieth century, a time frame too short to capture the full range of drought variability in the Pacific Northwest. Here we present a lumped parameter, mass-balance model that provides insight into the influence of hydroclimatological changes on two small, closed-basin systems located in north- central Washington. Steady state model simulations of lake water oxygen isotope ratios using modern climate and catchment parameter datasets demonstrate a strong sensitivity to both the amount and timing of precipitation, and to changes in summertime relative humidity, particularly at annual and decadal time scales. Model tests also suggest that basin hypsography can have a significant impact on lake water oxygen isotope variations, largely through surface area to volume and consequent evaporative flux to volume ratio changes in response to drought and pluvial sequences. Additional simulations using input parameters derived from both on-site and National Climatic Data Center historical climate datasets accurately approximate three years of continuous lake observations (seasonal water sampling and continuous lake level monitoring) and twentieth century oxygen isotope ratios in sediment core authigenic carbonate recovered from the lakes. Results from these model simulations suggest that small, closed-basin lakes in north-central Washington are highly sensitive to changes in the drought-related climate variables, and that long (8000 year), high resolution records of quantitative changes in precipitation and evaporation are obtainable from sediment cores recovered from water bodies of the Pacific Northwest.

Reduced-Order Structure-Preserving Model for Parallel-Connected Three-Phase Grid-Tied Inverters

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

Johnson, Brian B; Purba, Victor; Jafarpour, Saber

Next-generation power networks will contain large numbers of grid-connected inverters satisfying a significant fraction of system load. Since each inverter model has a relatively large number of dynamic states, it is impractical to analyze complex system models where the full dynamics of each inverter are retained. To address this challenge, we derive a reduced-order structure-preserving model for parallel-connected grid-tied three-phase inverters. Here, each inverter in the system is assumed to have a full-bridge topology, LCL filter at the point of common coupling, and the control architecture for each inverter includes a current controller, a power controller, and a phase-locked loopmore » for grid synchronization. We outline a structure-preserving reduced-order inverter model with lumped parameters for the setting where the parallel inverters are each designed such that the filter components and controller gains scale linearly with the power rating. By structure preserving, we mean that the reduced-order three-phase inverter model is also composed of an LCL filter, a power controller, current controller, and PLL. We show that the system of parallel inverters can be modeled exactly as one aggregated inverter unit and this equivalent model has the same number of dynamical states as any individual inverter in the system. Numerical simulations validate the reduced-order model.« less

Can we use the equivalent sphere model to approximate organ doses in space radiation environments?

NASA Astrophysics Data System (ADS)

Lin, Zi-Wei

For space radiation protection one often calculates the dose or dose equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However, previous studies have concluded that a 5cm sphere gives a very different dose from the exact BFO dose. One study concludes that a 9cm sphere is a reasonable approximation for the BFO dose in solar particle event (SPE) environments. In this study we investigate the reason behind these observations and extend earlier studies by studying whether BFO, eyes or the skin can be approximated by the equivalent sphere model in different space radiation environments such as solar particle events and galactic cosmic ray (GCR) environments. We take the thickness distribution functions of the organs from the CAM (Computerized Anatomical Man) model, then use a deterministic radiation transport to calculate organ doses in different space radiation environments. The organ doses have been evaluated with a water or aluminum shielding from 0 to 20 g/cm2. We then compare these exact doses with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we propose to use a modified equivalent sphere model with two radius parameters to represent the skin or eyes. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for eyes or the skin. For galactic cosmic rays environments, the equivalent sphere model with one organ-specific radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of eyes or the skin, but is unacceptable for the dose of eyes or the skin. The BFO radius parameters are found to be significantly larger than 5 cm in all cases, consistent with the conclusion of an earlier study. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and 11 cm for the BFO, 3.7 to 4.8 cm for eyes, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose. In the proposed modified equivalent sphere model, the range of each of the two radius parameters for the skin (or eyes) is much tighter than that in the equivalent sphere model with one radius parameter. Our results thus show that the equivalent sphere model works better in galactic cosmic rays environments than in solar particle events. The model works well or marginally well for BFO but usually does not work for eyes or the skin. A modified model with two radius parameters works much better in approximating the dose and dose equivalent in eyes or the skin.

45 CFR 158.241 - Form of rebate.

Code of Federal Regulations, 2012 CFR

2012-10-01

... check or lump-sum reimbursement using the same method that was used for payment, such as credit card or... in the form of a premium credit, lump-sum check, or, if an enrollee paid the premium using a credit card or direct debit, by lump-sum reimbursement to the account used to pay the premium. (2) Any rebate...

Microgravity-Induced Physiological Fluid Redistribution: Computational Analysis to Assess Influence of Physiological Parameters

NASA Technical Reports Server (NTRS)

Myers, J. G.; Eke, Chika; Werner, C.; Nelson, E. S.; Mulugeta, L.; Feola, A.; Raykin, J.; Samuels, B.; Ethier, C. R.

2016-01-01

Space flight impacts human physiology in many ways, the most immediate being the marked cephalad (headward) shift of fluid upon introduction into the microgravity environment. This physiological response to microgravity points to the redistribution of blood and interstitial fluid as a major factor in the loss of venous tone and reduction in heart muscle efficiency which impact astronaut performance. In addition, researchers have hypothesized that a reduction in astronaut visual acuity, part of the Visual Impairment and Intracranial Pressure (VIIP) syndrome, is associated with this redistribution of fluid. VIIP arises within several months of beginning space flight and includes a variety of ophthalmic changes including posterior globe flattening, distension of the optic nerve sheath, and kinking of the optic nerve. We utilize a suite of lumped parameter models to simulate microgravity-induced fluid redistribution in the cardiovascular, central nervous and ocular systems to provide initial and boundary data to a 3D finite element simulation of ocular biomechanics in VIIP. Specifically, the lumped parameter cardiovascular model acts as the primary means of establishing how microgravity, and the associated lack of hydrostatic gradient, impacts fluid redistribution. The cardiovascular model consists of 16 compartments, including three cerebrospinal fluid (CSF) compartments, three cranial blood compartments, and 10 thoracic and lower limb blood compartments. To assess the models capability to address variations in physiological parameters, we completed a formal uncertainty and sensitivity analysis that evaluated the relative importance of 42 input parameters required in the model on relative compartment flows and compartment pressures. Utilizing the model in a pulsatile flow configuration, the sensitivity analysis identified the ten parameters that most influenced each compartment pressure. Generally, each compartment responded appropriately to parameter variations associated with itself and adjacent compartments. However, several unexpected interactions between components, such as between the choroid plexus and the lower capillaries, were found, and are due to simplifications in the formulation of the model. The analysis illustrates that highly influential parameters and those that have unique influences within the model formulation must be tightly controlled for successful model application.

Affects of Anxiety and Depression on Health-Related Quality of Life among Patients with Benign Breast Lumps Diagnosed via Ultrasonography in China.

PubMed

Lou, Zhe; Li, Yinyan; Yang, Yilong; Wang, Lie; Yang, Jun

2015-08-28

There is a high incidence of benign breast lumps among women, and these lumps may lead to physical and psychological problems. This study aims to evaluate anxiety and depressive symptoms among patients with benign breast lumps diagnosed via ultrasonography and investigate their impacts on health-related quality of life (HRQOL). A cross-sectional survey was conducted in Shenyang, China, from January to November 2013. Data were collected with self-administered questionnaires, including the Zung Self-Rating Anxiety Scale (SAS), the Center for Epidemiologic Studies Depression Scale (CES-D), and the 36-item Short-Form Health Survey (SF-36), together with demographic characteristics, from patients of the Department of Breast Surgery of the First Affiliated Hospital of China Medical University. Hierarchical multiple regression analysis (HMR) was performed to explore the effects of anxiety and depression on HRQOL. The overall prevalences of anxiety (SAS score ≥ 40) and depression (CES-D scores ≥ 16) were 40.2% and 62.0%, respectively, and 37.5% of the participants had both of these psychological symptoms. The means and standard deviations of PCS and MCS were 75.42 (15.22) and 68.70 (17.71), respectively. Anxiety and depressive symptoms were significantly negatively associated with the HRQOL of patients with benign breast lumps diagnosed via ultrasonography. Women with benign breast lumps diagnosed via ultrasonography in China experienced relatively high levels of anxiety and depressive symptoms. Anxiety and depressive symptoms had significant negative impacts on both the mental and physical quality of life (QOL) of women with benign breast lumps. Beyond the necessary clinical treatment procedures, psychological guidance and detailed explanations of the disease should be offered to alleviate the anxiety and depressive symptoms and enhance the HRQOL of patients with benign breast lumps.

Wicking of liquids in screens

NASA Technical Reports Server (NTRS)

Symons, E. P.

1974-01-01

An investigation was conducted to determine the magnitude of the wicking rates of liquids in various screens. Evaluation of the parameters characterizing the wicking process resulted in the development of an expression which defined the wicking velocity in terms of screen and system geometry, liquid properties, and gravitational effects. Experiment data obtained both in normal gravity and in weightlessness demonstrated that the model successfully predicted the functional relation of the liquid properties and the distance from the liquid source to the wicking velocity. Because the pore geometry in the screens was complex, several screen geometric parameters were lumped into a single constant which was determined experimentally for each screen.

Tube-Load Model Parameter Estimation for Monitoring Arterial Hemodynamics

PubMed Central

Zhang, Guanqun; Hahn, Jin-Oh; Mukkamala, Ramakrishna

2011-01-01

A useful model of the arterial system is the uniform, lossless tube with parametric load. This tube-load model is able to account for wave propagation and reflection (unlike lumped-parameter models such as the Windkessel) while being defined by only a few parameters (unlike comprehensive distributed-parameter models). As a result, the parameters may be readily estimated by accurate fitting of the model to available arterial pressure and flow waveforms so as to permit improved monitoring of arterial hemodynamics. In this paper, we review tube-load model parameter estimation techniques that have appeared in the literature for monitoring wave reflection, large artery compliance, pulse transit time, and central aortic pressure. We begin by motivating the use of the tube-load model for parameter estimation. We then describe the tube-load model, its assumptions and validity, and approaches for estimating its parameters. We next summarize the various techniques and their experimental results while highlighting their advantages over conventional techniques. We conclude the review by suggesting future research directions and describing potential applications. PMID:22053157

29 CFR 4044.73 - Lump sums and other alternative forms of distribution in lieu of annuities.

Code of Federal Regulations, 2010 CFR

2010-07-01

... distribution is the present value of the normal form of benefit provided by the plan payable at normal... 29 Labor 9 2010-07-01 2010-07-01 false Lump sums and other alternative forms of distribution in... Benefits and Assets Non-Trusteed Plans § 4044.73 Lump sums and other alternative forms of distribution in...

20 CFR 222.31 - Relationship as child for annuity and lump-sum payment purposes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... that person is— (1) The natural or legally adopted child of the employee (see § 222.33); or (2) The... equitably adopted child of the employee. (b) Lump-sum payment claimant. A claimant for a lump-sum payment... of the employee; (2) A child legally adopted by the employee (this does not include any child adopted...

Decay of Kadomtsev-Petviashvili lumps in dissipative media

NASA Astrophysics Data System (ADS)

Clarke, S.; Gorshkov, K.; Grimshaw, R.; Stepanyants, Y.

2018-03-01

The decay of Kadomtsev-Petviashvili lumps is considered for a few typical dissipations-Rayleigh dissipation, Reynolds dissipation, Landau damping, Chezy bottom friction, viscous dissipation in the laminar boundary layer, and radiative losses caused by large-scale dispersion. It is shown that the straight-line motion of lumps is unstable under the influence of dissipation. The lump trajectories are calculated for two most typical models of dissipation-the Rayleigh and Reynolds dissipations. A comparison of analytical results obtained within the framework of asymptotic theory with the direct numerical calculations of the Kadomtsev-Petviashvili equation is presented. Good agreement between the theoretical and numerical results is obtained.

Analysis and synthesis of distributed-lumped-active networks by digital computer

NASA Technical Reports Server (NTRS)

1973-01-01

The use of digital computational techniques in the analysis and synthesis of DLA (distributed lumped active) networks is considered. This class of networks consists of three distinct types of elements, namely, distributed elements (modeled by partial differential equations), lumped elements (modeled by algebraic relations and ordinary differential equations), and active elements (modeled by algebraic relations). Such a characterization is applicable to a broad class of circuits, especially including those usually referred to as linear integrated circuits, since the fabrication techniques for such circuits readily produce elements which may be modeled as distributed, as well as the more conventional lumped and active ones.

Single lump breast surface stress assessment study

NASA Astrophysics Data System (ADS)

Vairavan, R.; Ong, N. R.; Sauli, Z.; Kirtsaeng, S.; Sakuntasathien, S.; Paitong, P.; Alcain, J. B.; Lai, S. L.; Retnasamy, V.

2017-09-01

Breast cancer is one of the commonest cancers diagnosed among women around the world. Simulation approach has been utilized to study, characterize and improvise detection methods for breast cancer. However, minimal simulation work has been done to evaluate the surface stress of the breast with lumps. Thus, in this work, simulation analysis was utilized to evaluate and assess the breast surface stress due to the presence of a lump within the internal structure of the breast. The simulation was conducted using the Elmer software. Simulation results have confirmed that the presence of a lump within the breast causes stress on the skin surface of the breast.

Ultrathin lightweight plate-type acoustic metamaterials with positive lumped coupling resonant

NASA Astrophysics Data System (ADS)

Ma, Fuyin; Huang, Meng; Wu, Jiu Hui

2017-01-01

The experimental realization and theoretical understanding of a two-dimensional multiple cells lumped ultrathin lightweight plate-type acoustic metamaterials structures have been presented, wherein broadband excellent sound attenuation ability at low frequencies is realized by employing a lumped element coupling resonant effect. The basic unit cell of the metamaterials consists of an ultrathin stiff nylon plate clamped by two elastic ethylene-vinyl acetate copolymer or acrylonitrile butadiene styrene frames. The strong sound attenuation (up to nearly 99%) at low frequencies is experimentally revealed by the precisely designed metamaterials, for which the physical mechanism of the sound attenuation could be explicitly understood using the finite element simulations. As to the designed samples, the lumped effect from the frame compliance leads to a coupling flexural resonance at designable low frequencies. As a result, the whole composite structure become strongly anti-resonant with the incident sound waves, followed by a higher sound attenuation, i.e., the lumped resonant effect has been effectively reversed to be positive from negative for sound attenuation, and the acoustic metamaterial design could be extended to the lumped element containing multiple cells, rather than confined to a single cell.

A simple distributed sediment delivery approach for rural catchments

NASA Astrophysics Data System (ADS)

Reid, Lucas; Scherer, Ulrike

2014-05-01

The transfer of sediments from source areas to surface waters is a complex process. In process based erosion models sediment input is thus quantified by representing all relevant sub processes such as detachment, transport and deposition of sediment particles along the flow path to the river. A successful application of these models requires, however, a large amount of spatially highly resolved data on physical catchment characteristics, which is only available for a few, well examined small catchments. For the lack of appropriate models, the empirical Universal Soil Loss Equation (USLE) is widely applied to quantify the sediment production in meso to large scale basins. As the USLE provides long-term mean soil loss rates, it is often combined with spatially lumped models to estimate the sediment delivery ratio (SDR). In these models, the SDR is related to data on morphological characteristics of the catchment such as average local relief, drainage density, proportion of depressions or soil texture. Some approaches include the relative distance between sediment source areas and the river channels. However, several studies showed that spatially lumped parameters describing the morphological characteristics are only of limited value to represent the factors of influence on sediment transport at the catchment scale. Sediment delivery is controlled by the location of the sediment source areas in the catchment and the morphology along the flow path to the surface water bodies. This complex interaction of spatially varied physiographic characteristics cannot be adequately represented by lumped morphological parameters. The objective of this study is to develop a simple but spatially distributed approach to quantify the sediment delivery ratio by considering the characteristics of the flow paths in a catchment. We selected a small catchment located in in an intensively cultivated loess region in Southwest Germany as study area for the development of the SDR approach. The flow pathways were extracted in a geographic information system. Then the sediment delivery ratio for each source area was determined using an empirical approach considering the slope, morphology and land use properties along the flow path. As a benchmark for the calibration of the model parameters we used results of a detailed process based erosion model available for the study area. Afterwards the approach was tested in larger catchments located in the same loess region.

Towards an atrio-ventricular delay optimization assessed by a computer model for cardiac resynchronization therapy

NASA Astrophysics Data System (ADS)

Ojeda, David; Le Rolle, Virginie; Tse Ve Koon, Kevin; Thebault, Christophe; Donal, Erwan; Hernández, Alfredo I.

2013-11-01

In this paper, lumped-parameter models of the cardiovascular system, the cardiac electrical conduction system and a pacemaker are coupled to generate mitral ow pro les for di erent atrio-ventricular delay (AVD) con gurations, in the context of cardiac resynchronization therapy (CRT). First, we perform a local sensitivity analysis of left ventricular and left atrial parameters on mitral ow characteristics, namely E and A wave amplitude, mitral ow duration, and mitral ow time integral. Additionally, a global sensitivity analysis over all model parameters is presented to screen for the most relevant parameters that a ect the same mitral ow characteristics. Results provide insight on the in uence of left ventricle and atrium in uence on mitral ow pro les. This information will be useful for future parameter estimation of the model that could reproduce the mitral ow pro les and cardiovascular hemodynamics of patients undergoing AVD optimization during CRT.

Characterization of high order spatial discretizations and lumping techniques for discontinuous finite element SN transport

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

Maginot, P. G.; Ragusa, J. C.; Morel, J. E.

2013-07-01

We examine several possible methods of mass matrix lumping for discontinuous finite element discrete ordinates transport using a Lagrange interpolatory polynomial trial space. Though positive outflow angular flux is guaranteed with traditional mass matrix lumping in a purely absorbing 1-D slab cell for the linear discontinuous approximation, we show that when used with higher degree interpolatory polynomial trial spaces, traditional lumping does yield strictly positive outflows and does not increase in accuracy with an increase in trial space polynomial degree. As an alternative, we examine methods which are 'self-lumping'. Self-lumping methods yield diagonal mass matrices by using numerical quadrature restrictedmore » to the Lagrange interpolatory points. Using equally-spaced interpolatory points, self-lumping is achieved through the use of closed Newton-Cotes formulas, resulting in strictly positive outflows in pure absorbers for odd power polynomials in 1-D slab geometry. By changing interpolatory points from the traditional equally-spaced points to the quadrature points of the Gauss-Legendre or Lobatto-Gauss-Legendre quadratures, it is possible to generate solution representations with a diagonal mass matrix and a strictly positive outflow for any degree polynomial solution representation in a pure absorber medium in 1-D slab geometry. Further, there is no inherent limit to local truncation error order of accuracy when using interpolatory points that correspond to the quadrature points of high order accuracy numerical quadrature schemes. (authors)« less

Analysing grouping of nucleotides in DNA sequences using lumped processes constructed from Markov chains.

PubMed

Guédon, Yann; d'Aubenton-Carafa, Yves; Thermes, Claude

2006-03-01

The most commonly used models for analysing local dependencies in DNA sequences are (high-order) Markov chains. Incorporating knowledge relative to the possible grouping of the nucleotides enables to define dedicated sub-classes of Markov chains. The problem of formulating lumpability hypotheses for a Markov chain is therefore addressed. In the classical approach to lumpability, this problem can be formulated as the determination of an appropriate state space (smaller than the original state space) such that the lumped chain defined on this state space retains the Markov property. We propose a different perspective on lumpability where the state space is fixed and the partitioning of this state space is represented by a one-to-many probabilistic function within a two-level stochastic process. Three nested classes of lumped processes can be defined in this way as sub-classes of first-order Markov chains. These lumped processes enable parsimonious reparameterizations of Markov chains that help to reveal relevant partitions of the state space. Characterizations of the lumped processes on the original transition probability matrix are derived. Different model selection methods relying either on hypothesis testing or on penalized log-likelihood criteria are presented as well as extensions to lumped processes constructed from high-order Markov chains. The relevance of the proposed approach to lumpability is illustrated by the analysis of DNA sequences. In particular, the use of lumped processes enables to highlight differences between intronic sequences and gene untranslated region sequences.

Comparative estimation and assessment of initial soil moisture conditions for Flash Flood warning in Saxony

NASA Astrophysics Data System (ADS)

Luong, Thanh Thi; Kronenberg, Rico; Bernhofer, Christian; Janabi, Firas Al; Schütze, Niels

2017-04-01

Flash Floods are known as highly destructive natural hazards due to their sudden appearance and severe consequences. In Saxony/Germany flash floods occur in small and medium catchments of low mountain ranges which are typically ungauged. Besides rainfall and orography, pre-event moisture is decisive, as it determines the available natural retention in the catchment. The Flash Flood Guidance concept according to WMO and Prof. Marco Borga (University of Padua) will be adapted to incorporate pre-event moisture in real-time flood forecast within the ESF EXTRUSO project (SAB-Nr. 100270097). To arrive at pre-event moisture for the complete area of the low mountain range with flash flood potential, a widely applicable, accurate but yet simple approach is needed. Here, we use radar precipitation as input time series, detailed orographic, land-use and soil information and a lumped parameter model to estimate the overall catchment soil moisture and potential retention. When combined with rainfall forecast and its intrinsic uncertainty, the approach allows to find the point in time when precipitation exceeds the retention potential of the catchment. Then, spatially distributed and complex hydrological modeling and additional measurements can be initiated. Assuming reasonable rainfall forecasts of 24 to 48hrs, this part can start up to two days in advance of the actual event. The lumped-parameter model BROOK90 is used and tested for well observed catchments. First, physical meaningful parameters (like albedo or soil porosity) a set according to standards and second, "free" parameters (like percentage of lateral flow) were calibrated objectively by PEST (Model-Independent Parameter Estimation and Uncertainty Analysis) with the target on evapotranspiration and soil moisture which both have been measured at the study site Anchor Station Tharandt in Saxony/Germany. Finally, first results are presented for the Wernersbach catchment in Tharandt forest for main flood events in the 50-year gauging period since 1968.

The Shock and Vibration Digest. Volume 12, Number 6,

DTIC Science & Technology

1980-06-01

I 20 .. I%25 1.4~ iu±.6 MICROCOPY RESOLUTION TESI CHARI 1 AIIONAL BURtAU Ua SIANDARDS I63 4 i’U 00 SVIC NOTES The weight saving advantages of...34Theoretical and Manifolds by Using Lumped Parameter De - Experimental Investigation of Valve Movement scriptions," J. Sound Vib., 64 (3), pp 387-402 and...COMPUTATIONAL TECHNIQUES work for the textbook through definitions and de - FOR INTERFACE PROBLEMS scriptions of dynamic systems, modeling procedures

Determination of timescales of nitrate contamination by groundwater age models in a complex aquifer system

NASA Astrophysics Data System (ADS)

Koh, E. H.; Lee, E.; Kaown, D.; Lee, K. K.; Green, C. T.

2017-12-01

Timing and magnitudes of nitrate contamination are determined by various factors like contaminant loading, recharge characteristics and geologic system. Information of an elapsed time since recharged water traveling to a certain outlet location, which is defined as groundwater age, can provide indirect interpretation related to the hydrologic characteristics of the aquifer system. There are three major methods (apparent ages, lumped parameter model, and numerical model) to date groundwater ages, which differently characterize groundwater mixing resulted by various groundwater flow pathways in a heterogeneous aquifer system. Therefore, in this study, we compared the three age models in a complex aquifer system by using observed age tracer data and reconstructed history of nitrate contamination by long-term source loading. The 3H-3He and CFC-12 apparent ages, which did not consider the groundwater mixing, estimated the most delayed response time and a highest period of the nitrate loading had not reached yet. However, the lumped parameter model could generate more recent loading response than the apparent ages and the peak loading period influenced the water quality. The numerical model could delineate various groundwater mixing components and its different impacts on nitrate dynamics in the complex aquifer system. The different age estimation methods lead to variations in the estimated contaminant loading history, in which the discrepancy in the age estimation was dominantly observed in the complex aquifer system.

Simulating nitrate response functions in watersheds: Case studies in the United States and New Zealand

NASA Astrophysics Data System (ADS)

Gusyev, Maksym; Abrams, Daniel; Morgenstern, Uwe; Stewart, Michael

2016-04-01

Non-point sources of nitrate contamination are a common concern in different parts of the world and are difficult to characterize. Due to the solubility of nitrate, it easily enters groundwater and may take years or decades to completely flush to a stream. During this time, it may undergo denitrification, in particular if dissolved oxygen levels are low, requiring a representation of spatially distributed nitrate input as well as detailed hydrogeology. In this presentation, nitrate response functions are generated with four different methodologies that are listed in the order of decreasing degrees of freedom: groundwater flow and chemical transport (MODFLOW/MT3D), groundwater flow with solute particle tracing (MODFLOW/MODPATH), cross-sectional groundwater flow model (MODFLOW), and lumped parameter models (LPMs). We tested these approaches in selected watersheds in the Eastern and Midwestern United States as well as New Zealand and found similar nitrate results in all cases despite different model complexities. It is noted that only the fully three dimensional MODFLOW models with MT3D or MODPATH could account for detailed patterns of land use and nitrate applications; the cross-sectional models and lumped parameter models could only do so approximately. Denitrification at depth could also be explicitly accounted for in all four approaches, although this was not a major factor in any of the watersheds investigated.

Statistical Validation of Surrogate Endpoints: Another Look at the Prentice Criterion and Other Criteria.

PubMed

Saraf, Sanatan; Mathew, Thomas; Roy, Anindya

2015-01-01

For the statistical validation of surrogate endpoints, an alternative formulation is proposed for testing Prentice's fourth criterion, under a bivariate normal model. In such a setup, the criterion involves inference concerning an appropriate regression parameter, and the criterion holds if the regression parameter is zero. Testing such a null hypothesis has been criticized in the literature since it can only be used to reject a poor surrogate, and not to validate a good surrogate. In order to circumvent this, an equivalence hypothesis is formulated for the regression parameter, namely the hypothesis that the parameter is equivalent to zero. Such an equivalence hypothesis is formulated as an alternative hypothesis, so that the surrogate endpoint is statistically validated when the null hypothesis is rejected. Confidence intervals for the regression parameter and tests for the equivalence hypothesis are proposed using bootstrap methods and small sample asymptotics, and their performances are numerically evaluated and recommendations are made. The choice of the equivalence margin is a regulatory issue that needs to be addressed. The proposed equivalence testing formulation is also adopted for other parameters that have been proposed in the literature on surrogate endpoint validation, namely, the relative effect and proportion explained.

Modeling Wind Wave Evolution from Deep to Shallow Water

DTIC Science & Technology

2011-09-30

validation and calibration of new model developments. WORK COMPLETED Development of a Lumped Quadruplet Approximation ( LQA ) To make evaluation of the...interactions based on the WRT method. This Lumped Quadruplet Approximation ( LQA ) clusters (lumps) contributions to the integrations over the...total transfer rate. A procedure has been developed to test the implementation (of LQA and other reduced versions of the WRT) where 1) the non

Dynamics of a distributed drill string system: Characteristic parameters and stability maps

NASA Astrophysics Data System (ADS)

Aarsnes, Ulf Jakob F.; van de Wouw, Nathan

2018-03-01

This paper involves the dynamic (stability) analysis of distributed drill-string systems. A minimal set of parameters characterizing the linearized, axial-torsional dynamics of a distributed drill string coupled through the bit-rock interaction is derived. This is found to correspond to five parameters for a simple drill string and eight parameters for a two-sectioned drill-string (e.g., corresponding to the pipe and collar sections of a drilling system). These dynamic characterizations are used to plot the inverse gain margin of the system, parametrized in the non-dimensional parameters, effectively creating a stability map covering the full range of realistic physical parameters. This analysis reveals a complex spectrum of dynamics not evident in stability analysis with lumped models, thus indicating the importance of analysis using distributed models. Moreover, it reveals trends concerning stability properties depending on key system parameters useful in the context of system and control design aiming at the mitigation of vibrations.

Modeling of a carbon nanotube ultracapacitor.

PubMed

Orphanou, Antonis; Yamada, Toshishige; Yang, Cary Y

2012-03-09

The modeling of carbon nanotube ultracapacitor (CNU) performance based on the simulation of electrolyte ion motion between the cathode and the anode is described. Using a molecular dynamics (MD) approach, the equilibrium positions of the electrode charges interacting through the Coulomb potential are determined, which in turn yield the equipotential surface and electric field associated with the capacitor. With an applied ac voltage, the current is computed based on the nanotube and electrolyte particle distribution and interaction, resulting in the frequency-dependent impedance Z(ω). From the current and impedance profiles, the Nyquist and cyclic voltammetry (CV) plots are then extracted. The results of these calculations compare well with existing experimental data. A lumped-element equivalent circuit for the CNU is proposed and the impedance computed from this circuit correlates well with the simulated and measured impedances.

Optical Kerr Spatiotemporal Dark-Lump Dynamics of Hydrodynamic Origin

NASA Astrophysics Data System (ADS)

Baronio, Fabio; Wabnitz, Stefan; Kodama, Yuji

2016-04-01

There is considerable fundamental and applicative interest in obtaining nondiffractive and nondispersive spatiotemporal localized wave packets propagating in optical cubic nonlinear or Kerr media. Here, we analytically predict the existence of a novel family of spatiotemporal dark lump solitary wave solutions of the (2 +1 )D nonlinear Schrödinger equation. Dark lumps represent multidimensional holes of light on a continuous wave background. We analytically derive the dark lumps from the hydrodynamic exact soliton solutions of the (2 +1 )D shallow water Kadomtsev-Petviashvili model, inheriting their complex interaction properties. This finding opens a novel path for the excitation and control of optical spatiotemporal waveforms of hydrodynamic footprint and multidimensional optical extreme wave phenomena.

Optical Kerr Spatiotemporal Dark-Lump Dynamics of Hydrodynamic Origin.

PubMed

Baronio, Fabio; Wabnitz, Stefan; Kodama, Yuji

2016-04-29

There is considerable fundamental and applicative interest in obtaining nondiffractive and nondispersive spatiotemporal localized wave packets propagating in optical cubic nonlinear or Kerr media. Here, we analytically predict the existence of a novel family of spatiotemporal dark lump solitary wave solutions of the (2+1)D nonlinear Schrödinger equation. Dark lumps represent multidimensional holes of light on a continuous wave background. We analytically derive the dark lumps from the hydrodynamic exact soliton solutions of the (2+1)D shallow water Kadomtsev-Petviashvili model, inheriting their complex interaction properties. This finding opens a novel path for the excitation and control of optical spatiotemporal waveforms of hydrodynamic footprint and multidimensional optical extreme wave phenomena.

Estimation of outer-middle ear transmission using DPOAEs and fractional-order modeling of human middle ear

NASA Astrophysics Data System (ADS)

Naghibolhosseini, Maryam

Our ability to hear depends primarily on sound waves traveling through the outer and middle ear toward the inner ear. Hence, the characteristics of the outer and middle ear affect sound transmission to/from the inner ear. The role of the middle and outer ear in sound transmission is particularly important for otoacoustic emissions (OAEs), which are sound signals generated in a healthy cochlea, and recorded by a sensitive microphone placed in the ear canal. OAEs are used to evaluate the health and function of the cochlea; however, they are also affected by outer and middle ear characteristics. To better assess cochlear health using OAEs, it is critical to quantify the impact of the outer and middle ear on sound transmission. The reported research introduces a noninvasive approach to estimate outer-middle ear transmission using distortion product otoacoustic emissions (DPOAEs). In addition, the role of the outer and middle ear on sound transmission was investigated by developing a physical/mathematical model, which employed fractional-order lumped elements to include the viscoelastic characteristics of biological tissues. Impedance estimations from wideband refectance measurements were used for parameter fitting of the model. The model was validated comparing its estimates of the outer-middle ear sound transmission with those given by DPOAEs. The outer-middle ear transmission by the model was defined as the sum of forward and reverse outer-middle ear transmissions. To estimate the reverse transmission by the model, the probe-microphone impedance was calculated through estimating the Thevenin-equivalent circuit of the probe-microphone. The Thevenin-equivalent circuit was calculated using measurements in a number of test cavities. Such modeling enhances our understanding of the roles of different parts of the outer and middle ear and how they work together to determine their function. In addition, the model would be potentially helpful in diagnosing pathologies of cochlear or middle ear origin.

Comparative study of contrast-enhanced ultrasound qualitative and quantitative analysis for identifying benign and malignant breast tumor lumps.

PubMed

Liu, Jian; Gao, Yun-Hua; Li, Ding-Dong; Gao, Yan-Chun; Hou, Ling-Mi; Xie, Ting

2014-01-01

To compare the value of contrast-enhanced ultrasound (CEUS) qualitative and quantitative analysis in the identification of breast tumor lumps. Qualitative and quantitative indicators of CEUS for 73 cases of breast tumor lumps were retrospectively analyzed by univariate and multivariate approaches. Logistic regression was applied and ROC curves were drawn for evaluation and comparison. The CEUS qualitative indicator-generated regression equation contained three indicators, namely enhanced homogeneity, diameter line expansion and peak intensity grading, which demonstrated prediction accuracy for benign and malignant breast tumor lumps of 91.8%; the quantitative indicator-generated regression equation only contained one indicator, namely the relative peak intensity, and its prediction accuracy was 61.5%. The corresponding areas under the ROC curve for qualitative and quantitative analyses were 91.3% and 75.7%, respectively, which exhibited a statistically significant difference by the Z test (P<0.05). The ability of CEUS qualitative analysis to identify breast tumor lumps is better than with quantitative analysis.

Breast Lumps

MedlinePlus

... 2015. Raftery AT, et al. Breast lumps. In: Churchill's Pocketbook of Differential Diagnosis. 4th ed. Philadelphia, Pa.: Churchill Livingston Elsevier; 2014. http://www.clinicalkey.com. Accessed ...

Can the Equivalent Sphere Model Approximate Organ Doses in Space Radiation Environments?

NASA Technical Reports Server (NTRS)

Zi-Wei, Lin

2007-01-01

In space radiation calculations it is often useful to calculate the dose or dose equivalent in blood-forming organs (BFO). the skin or the eye. It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However previous studies have shown that a 5cm sphere gives conservative dose values for BFO. In this study we use a deterministic radiation transport with the Computerized Anatomical Man model to investigate whether the equivalent sphere model can approximate organ doses in space radiation environments. We find that for galactic cosmic rays environments the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent and marginally well for the BFO dose and the dose equivalent of the eye or the skin. For solar particle events the radius parameters for the organ dose equivalent increase with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin The ranges of the radius parameters are also shown and the BFO radius parameters are found to be significantly larger than 5 cm in all eases.

29 CFR Appendix C to Part 4022 - Lump Sum Interest Rates for Private-Sector Payments

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 9 2010-07-01 2010-07-01 false Lump Sum Interest Rates for Private-Sector Payments C... Appendix C to Part 4022—Lump Sum Interest Rates for Private-Sector Payments [In using this table: (1) For... (where y is an integer and 0 n 1 + n 2), interest rate i 3 shall apply from the valuation date for a...

29 CFR Appendix B to Part 4022 - Lump Sum Interest Rates for PBGC Payments

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 9 2010-07-01 2010-07-01 false Lump Sum Interest Rates for PBGC Payments B Appendix B to... 4022—Lump Sum Interest Rates for PBGC Payments [In using this table: (1) For benefits for which the... + n2), interest rate i3 shall apply from the valuation date for a period of y−n1−n2 years; interest...

Rogue Waves and Lump Solitons of the (3+1)-Dimensional Generalized B-type Kadomtsev-Petviashvili Equation for Water Waves

NASA Astrophysics Data System (ADS)

Sun, Yan; Tian, Bo; Liu, Lei; Chai, Han-Peng; Yuan, Yu-Qiang

2017-12-01

In this paper, the (3+1)-dimensional generalized B-type Kadomtsev-Petviashvili equation for water waves is investigated. Through the Hirota method and Kadomtsev-Petviashvili hierarchy reduction, we obtain the first-order, higher-order, multiple rogue waves and lump solitons based on the solutions in terms of the Gramian. The first-order rogue waves are the line rogue waves which arise from the constant background and then disappear into the constant background again, while the first-order lump solitons propagate stably. Interactions among several first-order rogue waves which are described by the multiple rogue waves are presented. Elastic interactions of several first-order lump solitons are also presented. We find that the higher-order rogue waves and lump solitons can be treated as the superpositions of several first-order ones, while the interaction between the second-order lump solitons is inelastic. Supported by the National Natural Science Foundation of China under Grant Nos. 11772017, 11272023, and 11471050, by the Open Fund of State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), China (IPOC: 2017ZZ05), and by the Fundamental Research Funds for the Central Universities of China under Grant No. 2011BUPTYB02

Axillary silicone lymphadenopathy presenting with a lump and altered sensation in the breast: a case report

PubMed Central

2009-01-01

Introduction Silicone lymphadenopathy is a rare but recognised complication of procedures involving the use of silicone. It has a poorly understood mechanism but is thought to occur following the transportation of silicone particles from silicone-containing prostheses to lymph nodes by macrophages. Case presentation We report of a case involving a 35-year-old woman who presented to the breast clinic with a breast lump and altered sensation below her left nipple 5 years after bilateral cosmetic breast augmentations. A small lump was detected inferior to the nipple but clinical examination and initial ultrasound investigation showed both implants to be intact. However, mammography and magnetic resonance imaging of both breasts revealed both intracapsular and extracapsular rupture of the left breast prosthesis. The patient went on to develop a flu-like illness and tender lumps in the left axilla and right mastoid regions. An excision biopsy of the left axillary lesion and replacement of the ruptured implant was performed. Subsequent histological analysis showed that the axillary lump was a lymph node containing large amounts of silicone. Conclusion The exclusion of malignancy remains the priority when dealing with lumps in the breast or axilla. Silicone lymphadenopathy should however be considered as a differential diagnosis in patients in whom silicone prostheses are present. PMID:19830102

Transformation to equivalent dimensions—a new methodology to study earthquake clustering

NASA Astrophysics Data System (ADS)

Lasocki, Stanislaw

2014-05-01

A seismic event is represented by a point in a parameter space, quantified by the vector of parameter values. Studies of earthquake clustering involve considering distances between such points in multidimensional spaces. However, the metrics of earthquake parameters are different, hence the metric in a multidimensional parameter space cannot be readily defined. The present paper proposes a solution of this metric problem based on a concept of probabilistic equivalence of earthquake parameters. Under this concept the lengths of parameter intervals are equivalent if the probability for earthquakes to take values from either interval is the same. Earthquake clustering is studied in an equivalent rather than the original dimensions space, where the equivalent dimension (ED) of a parameter is its cumulative distribution function. All transformed parameters are of linear scale in [0, 1] interval and the distance between earthquakes represented by vectors in any ED space is Euclidean. The unknown, in general, cumulative distributions of earthquake parameters are estimated from earthquake catalogues by means of the model-free non-parametric kernel estimation method. Potential of the transformation to EDs is illustrated by two examples of use: to find hierarchically closest neighbours in time-space and to assess temporal variations of earthquake clustering in a specific 4-D phase space.

Rutting resistance of asphalt mixture with cup lumps modified binder

NASA Astrophysics Data System (ADS)

Shaffie, E.; Hanif, W. M. M. Wan; Arshad, A. K.; Hashim, W.

2017-11-01

Rutting is the most common pavement distress in pavement structures which occurs mainly due to several factors such as increasing of traffic volume, climatic conditions and also due to construction design errors. This failure reduced the service life of the pavement, reduced driver safety and increase cost of maintenance. Polymer Modified Binder has been observed for a long time in improving asphalt pavement performance. Research shows that the use of polymer in bituminous mix not only improve the resistance to rutting but also increase the life span of the pavement. This research evaluates the physical properties and rutting performance of dense graded Superpave-designed HMA mix. Two different types of dense graded Superpave HMA mix were developed consists of unmodified binder mix (UMB) and cup lumps rubber (liquid form) modified binder mix (CLMB). Natural rubber polymer modified binder was prepared from addition of 8 percent of cup lumps into binder. Results showed that all the mixes passed the Superpave volumetric properties criteria which indicate that these mixtures were good with respect to durability and flexibility. Furthermore, rutting results from APA rutting test was determined to evaluate the performance of these mixtures. The rutting result of CLMB demonstrates better resistance to rutting than those prepared using UMB mix. Addition of cup lumps rubber in asphalt mixture was found to be significant, where the cup lumps rubber has certainly improves the binder properties and enhanced its rutting resistance due to greater elasticity offered by the cup lumps rubber particles. It shows that the use of cup lumps rubber can significantly reduce the rut depth of asphalt mixture by 41% compared to the minimum rut depth obtained for the UMB mix. Therefore, it can be concluded that the cup lumps rubber is suitable to be used as a modifier to modified binder in order to enhance the properties of the binder and thus improves the performance of asphalt mixes.

Maturity of lumped element kinetic inductance detectors for space-borne instruments in the range between 80 and 180 GHz

NASA Astrophysics Data System (ADS)

Catalano, A.; Benoit, A.; Bourrion, O.; Calvo, M.; Coiffard, G.; D'Addabbo, A.; Goupy, J.; Le Sueur, H.; Macías-Pérez, J.; Monfardini, A.

2016-07-01

This work intends to give the state-of-the-art of our knowledge of the performance of lumped element kinetic inductance detectors (LEKIDs) at millimetre wavelengths (from 80 to 180 GHz). We evaluate their optical sensitivity under typical background conditions that are representative of a space environment and their interaction with ionising particles. Two LEKID arrays, originally designed for ground-based applications and composed of a few hundred pixels each, operate at a central frequency of 100 and 150 GHz (Δν/ν about 0.3). Their sensitivities were characterised in the laboratory using a dedicated closed-cycle 100 mK dilution cryostat and a sky simulator, allowing for the reproduction of realistic, space-like observation conditions. The impact of cosmic rays was evaluated by exposing the LEKID arrays to alpha particles (241Am) and X sources (109Cd), with a read-out sampling frequency similar to those used for Planck HFI (about 200 Hz), and also with a high resolution sampling level (up to 2 MHz) to better characterise and interpret the observed glitches. In parallel, we developed an analytical model to rescale the results to what would be observed by such a LEKID array at the second Lagrangian point. We show that LEKID arrays behave adequately in space-like conditions with a measured noise equivalent power close to the cosmic microwave background photon noise and an impact of cosmic rays smaller with respect to those observed with Planck satellite detectors.

Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains and microbial community succession analysis

NASA Astrophysics Data System (ADS)

Hao, Xiao-dong; Liang, Yi-li; Yin, Hua-qun; Liu, Hong-wei; Zeng, Wei-min; Liu, Xue-duan

2017-04-01

Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains was carried out by mixed cultures on a small scale over a period of 210 d. Lump ores as a framework were loaded at the bottom of the ore heap. The overall copper leaching rates of tailings and lump ores were 57.10wt% and 65.52wt%, respectively. The dynamic shifts of microbial community structures about attached microorganisms were determined using the Illumina MiSeq sequencing platform based on 16S rRNA amplification strategy. The results indicated that chemolithotrophic genera Acidithiobacillus and Leptospirillum were always detected and dominated the microbial community in the initial and middle stages of the heap bioleaching process; both genera might be responsible for improving the copper extraction. However, Thermogymnomonas and Ferroplasma increased gradually in the final stage. Moreover, the effects of various physicochemical parameters and microbial community shifts on the leaching efficiency were further investigated and these associations provided some important clues for facilitating the effective application of bioleaching.

Lumped Multi-Bubble Analysis of Injection Cooling System for Storage of Cryogenic Liquids

NASA Astrophysics Data System (ADS)

Saha, Pritam; Sandilya, Pavitra

2017-12-01

Storage of cryogenic liquids is a critical issue in many cryogenic applications. Subcooling of the liquid by bubbling a gas has been suggested to extend the storage period by reducing the boil-off loss. Liquid evaporation into the gas may cause liquid subcooling by extracting the latent heat of vaporization from the liquid. The present study aims at studying the factors affecting the liquid subcooling during gas injection. A lumped parameter model is presented to capture the effects of bubble dynamics (coalescence, breakup, deformation etc.) on the heat and mass transport between the gas and the liquid. The liquid subcooling has been estimated as a function of the key operating variables such as gas flow rate and gas injection temperature. Numerical results have been found to predict the change in the liquid temperature drop reasonably well when compared with the previously reported experimental results. This modelling approach can therefore be used in gauging the significance of various process variables on the liquid subcooling by injection cooling, as well as in designing and rating an injection cooling system.

Excellent low-frequency sound absorption of radial membrane acoustic metamaterial

NASA Astrophysics Data System (ADS)

Gao, Nansha; Wu, Jiu Hui; Hou, Hong; Yu, Lie

2017-01-01

This paper proposes a new radial membrane acoustic metamaterial (RMAM) structure, wherein a layer membrane substrate is covered with a rigid ring (polymethyl methacrylate frame and aluminum lump). The dispersion relationships, transmission spectra and displacement fields of the eigenmodes of this radial membrane acoustic metamaterial are studied with FEM. In contrast to the traditional radial phononic crystals (RPCs), the proposed structures can open bandgaps (BGs) in lower frequency range (0-300 Hz). Simulation results show that the physical mechanism behind the bandgaps is the coupling effects between the rotational vibration of aluminum lump and the transverse vibration of membrane. Geometrical parameters which can adjust the bandgaps’ widths or positions are analyzed. Finally, we investigate the axial sound transmission loss of this acoustic metamaterial structure, and discuss the effects of factor loss, membrane thickness and the number of layers of unit cell on the axial sound transmission loss. Dynamic effective density proves the accuracy of the FEM results. This kind of structure has potential application in pipe or circular ring structure for damping/noise reduction.

Can the Equivalent Sphere Model Approximate Organ Doses in Space?

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2007-01-01

For space radiation protection it is often useful to calculate dose or dose,equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to. simulate the BFO dose. However, many previous studies have concluded that a 5cm sphere gives very different dose values from the exact BFO values. One study [1] . concludes that a 9 cm sphere is a reasonable approximation for BFO'doses in solar particle event environments. In this study we use a deterministic radiation transport [2] to investigate the reason behind these observations and to extend earlier studies. We take different space radiation environments, including seven galactic cosmic ray environments and six large solar particle events, and calculate the dose and dose equivalent in the skin, eyes and BFO using their thickness distribution functions from the CAM (Computerized Anatomical Man) model [3] The organ doses have been evaluated with a water or aluminum shielding of an areal density from 0 to 20 g/sq cm. We then compare with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we address why the equivalent sphere model is not a good approximation in some cases. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin. For galactic cosmic rays environments, the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of the eye or the skin, but is unacceptable for the dose of the eye or the skin. The ranges of the radius parameters are also being investigated, and the BFO radius parameters are found to be significantly, larger than 5 cm in all cases, consistent with the conclusion of an earlier study [I]. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and I I cm for the BFO, 3.7 to 4.8 cm for the eye, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose.

41 CFR 302-6.203 - May I retain any balance left over from my TQSE lump sum payment if such payment is more than...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 4 2013-07-01 2012-07-01 true May I retain any balance left over from my TQSE lump sum payment if such payment is more than adequate? 302-6.203 Section 302-6... TEMPORARY QUARTERS SUBSISTENCE EXPENSES Lump Sum Payment § 302-6.203 May I retain any balance left over from...

41 CFR 302-5.18 - May I retain any balance left over from my househunting reimbursement if my lump sum is more than...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 41 Public Contracts and Property Management 4 2012-07-01 2012-07-01 false May I retain any balance left over from my househunting reimbursement if my lump sum is more than adequate to cover my... Expenses § 302-5.18 May I retain any balance left over from my househunting reimbursement if my lump sum is...

41 CFR 302-6.203 - May I retain any balance left over from my TQSE lump sum payment if such payment is more than...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 41 Public Contracts and Property Management 4 2014-07-01 2014-07-01 false May I retain any balance left over from my TQSE lump sum payment if such payment is more than adequate? 302-6.203 Section 302-6... TEMPORARY QUARTERS SUBSISTENCE EXPENSES Lump Sum Payment § 302-6.203 May I retain any balance left over from...

41 CFR 302-5.18 - May I retain any balance left over from my househunting reimbursement if my lump sum is more than...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 41 Public Contracts and Property Management 4 2014-07-01 2014-07-01 false May I retain any balance left over from my househunting reimbursement if my lump sum is more than adequate to cover my... Expenses § 302-5.18 May I retain any balance left over from my househunting reimbursement if my lump sum is...

41 CFR 302-6.203 - May I retain any balance left over from my TQSE lump sum payment if such payment is more than...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 41 Public Contracts and Property Management 4 2012-07-01 2012-07-01 false May I retain any balance left over from my TQSE lump sum payment if such payment is more than adequate? 302-6.203 Section 302-6... TEMPORARY QUARTERS SUBSISTENCE EXPENSES Lump Sum Payment § 302-6.203 May I retain any balance left over from...

41 CFR 302-5.18 - May I retain any balance left over from my househunting reimbursement if my lump sum is more than...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 4 2013-07-01 2012-07-01 true May I retain any balance left over from my househunting reimbursement if my lump sum is more than adequate to cover my... Expenses § 302-5.18 May I retain any balance left over from my househunting reimbursement if my lump sum is...

An interactive method based on the live wire for segmentation of the breast in mammography images.

PubMed

Zewei, Zhang; Tianyue, Wang; Li, Guo; Tingting, Wang; Lu, Xu

2014-01-01

In order to improve accuracy of computer-aided diagnosis of breast lumps, the authors introduce an improved interactive segmentation method based on Live Wire. This paper presents the Gabor filters and FCM clustering algorithm is introduced to the Live Wire cost function definition. According to the image FCM analysis for image edge enhancement, we eliminate the interference of weak edge and access external features clear segmentation results of breast lumps through improving Live Wire on two cases of breast segmentation data. Compared with the traditional method of image segmentation, experimental results show that the method achieves more accurate segmentation of breast lumps and provides more accurate objective basis on quantitative and qualitative analysis of breast lumps.

Inverse dynamics of adaptive structures used as space cranes

NASA Technical Reports Server (NTRS)

Das, S. K.; Utku, S.; Wada, B. K.

1990-01-01

As a precursor to the real-time control of fast moving adaptive structures used as space cranes, a formulation is given for the flexibility induced motion relative to the nominal motion (i.e., the motion that assumes no flexibility) and for obtaining the open loop time varying driving forces. An algorithm is proposed for the computation of the relative motion and driving forces. The governing equations are given in matrix form with explicit functional dependencies. A simulator is developed to implement the algorithm on a digital computer. In the formulations, the distributed mass of the crane is lumped by two schemes, vz., 'trapezoidal' lumping and 'Simpson's rule' lumping. The effects of the mass lumping schemes are shown by simulator runs.

On Theoretical Limits of Dynamic Model Updating Using a Sensitivity-Based Approach

NASA Astrophysics Data System (ADS)

GOLA, M. M.; SOMÀ, A.; BOTTO, D.

2001-07-01

The present work deals with the determination of the newly discovered conditions necessary for model updating with the eigensensitivity approach. The treatment concerns the maximum number of identifiable parameters regarding the structure of the eigenvectors derivatives. A mathematical demonstration is based on the evaluation of the rank of the least-squares matrix and produces the algebraic limiting conditions. Numerical application to a lumped parameter structure is employed to validate the mathematical limits taking into account different subsets of mode shapes. The demonstration is extended to the calculation of the eigenvector derivatives with both the Fox and Kapoor, and Nelson methods. III conditioning of the least-squares sensitivity matrix is revealed through the covariance jump.

Fluid dynamics in flexible tubes: An application to the study of the pulmonary circulation

NASA Technical Reports Server (NTRS)

Kuchar, N. R.

1971-01-01

Based on an analysis of unsteady, viscous flow through distensible tubes, a lumped-parameter model for the dynamics of blood flow through the pulmonary vascular bed was developed. The model is nonlinear, incorporating the variation of flow resistance with transmural pressure. Solved using a hybrid computer, the model yields information concerning the time-dependent behavior of blood pressures, flow rates, and volumes in each important class of vessels in each lobe of each lung in terms of the important physical and environmental parameters. Simulations of twenty abnormal or pathological situations of interest in environmental physiology and clinical medicine were performed. The model predictions agree well with physiological data.

Combustion stability analysis of preburners in liquid propellant rocket engines during shutdown

NASA Technical Reports Server (NTRS)

Lim, Kair-Chuan; George, Paul E., II

1987-01-01

A linearized one-dimensional lumped-parameter model capable of predicting the occurrence of the low frequency combustion instability (chugging) experienced during preburner shutdown in the Space Shuttle Main Engines is discussed, and predictions are compared with NASA experimental results. Results from a parametric study of parameters including chamber pressure, fuel and oxygen temperatures, and the effective bulk modulus of the liquid oxidizer suggest that chugging is probably affected by conditions at shutdown through the fuel and oxidizer temperatures. It is suggested that chugging is initiated when the fuel, oxidizer, and helium temperature and flow rates pass into an unstable region, and that chugging may be terminated by decaying pressures.

Interpretation of current-voltage relationships for "active" ion transport systems: I. Steady-state reaction-kinetic analysis of class-I mechanisms.

PubMed

Hansen, U P; Gradmann, D; Sanders, D; Slayman, C L

1981-01-01

This paper develops a simple reaction-kinetic model to describe electrogenic pumping and co- (or counter-) transport of ions. It uses the standard steady-state approach for cyclic enzyme- or carrier-mediated transport, but does not assume rate-limitation by any particular reaction step. Voltage-dependence is introduced, after the suggestion of Läuger and Stark (Biochim. Biophys. Acta 211:458-466, 1970), via a symmetric Eyring barrier, in which the charge-transit reaction constants are written as k12 = ko12 exp(zF delta psi/2RT) and k21 = ko21 exp(-zF delta psi/2RT). For interpretation of current-voltage relationships, all voltage-independent reaction steps are lumped together, so the model in its simplest form can be described as a pseudo-2-state model. It is characterized by the two voltage-dependent reaction constants, two lumped voltage-independent reaction constants (k12, k21), and two reserve factors (ri, ro) which formally take account of carrier states that are indistinguishable in the current-voltage (I-V) analysis. The model generates a wide range of I-V relationships, depending on the relative magnitudes of the four reaction constants, sufficient to describe essentially all I-V datas now available on "active" ion-transport systems. Algebraic and numerical analysis of the reserve factors, by means of expanded pseudo-3-, 4-, and 5-state models, shows them to be bounded and not large for most combinations of reaction constants in the lumped pathway. The most important exception to this rule occurs when carrier decharging immediately follows charge transit of the membrane and is very fast relative to other constituent voltage-independent reactions. Such a circumstance generates kinetic equivalence of chemical and electrical gradients, thus providing a consistent definition of ion-motive forces (e.g., proton-motive force, PMF). With appropriate restrictions, it also yields both linear and log-linear relationships between net transport velocity and either membrane potential or PMF. The model thus accommodates many known properties of proton-transport systems, particularly as observed in "chemiosmotic" or energy-coupling membranes.

Comparison of Lumped and Distributed Hydrologic Models Used for Planning and Water Resources Management at the Combeima River Basin, Colombia.

NASA Astrophysics Data System (ADS)

Salgado, F., II; Vélez, J.

2014-12-01

The catchment area is considered as the planning unit of natural resources where multiple factors as biotic, abiotic and human interact in a web of relationships making this unit a complex system. It is also considered by several authors as the most suitable unit for studying the water movement in nature and a tool for the understanding of natural processes. This research implements several hydrological models commonly used in water resources management and planning. It is the case of Témez, abcd, T, P, ARMA (1,1), and the lumped conceptual model TETIS. This latest model has been implemented in its distributed version for comparison purposes and it has been the basis for obtaining information, either through the reconstruction of natural flow series, filling missing data, forecasting or simulation. Hydrological models make use of lumped data of precipitation and potential evapotranspiration, as well as the following parameters for each one of the models which are related to soil properties as capillary storage capacity; the hydraulic saturated conductivity of the upper and lower layers of the soil, and residence times in the flow surface, subsurface layers and base flow. The calibration and the validation process of the models were performed making adjustments to the parameters listed above, taking into account the consistency in the efficiency indexes and the adjustment between the observed and simulated flows using the flow duration curve. The Nash index gave good results for the TETIS model and acceptable values were obtained to the other models. The calibration of the distributed model was complex and its results were similar to those obtained with the aggregated model. This comparison allows planners to use the hydrological multimodel techniques to reduce the uncertainty associated with planning processes in developing countries. Moreover, taking into account the information limitations required to implement a hydrological models, this application can be a good approach to water resources management. This project can be an important tool for decision making of different actors, such as local government, environmental agencies (CORTOLIMA), risk management office. Finally, the establishment of an improved network of hydro-meteorological stations that allow acquiring a better quality information.

Dynamic model including piping acoustics of a centrifugal compression system

NASA Astrophysics Data System (ADS)

van Helvoirt, Jan; de Jager, Bram

2007-04-01

This paper deals with low-frequency pulsation phenomena in full-scale centrifugal compression systems associated with compressor surge. The Greitzer lumped parameter model is applied to describe the dynamic behavior of an industrial compressor test rig and experimental evidence is provided for the presence of acoustic pulsations in the compression system under study. It is argued that these acoustic phenomena are common for full-scale compression systems where pipe system dynamics have a significant influence on the overall system behavior. The main objective of this paper is to extend the basic compressor model in order to include the relevant pipe system dynamics. For this purpose a pipeline model is proposed, based on previous developments for fluid transmission lines. The connection of this model to the lumped parameter model is accomplished via the selection of appropriate boundary conditions. Validation results will be presented, showing a good agreement between simulation and measurement data. The results indicate that the damping of piping transients depends on the nominal, time-varying pressure and flow velocity. Therefore, model parameters are made dependent on the momentary pressure and a switching nonlinearity is introduced into the model to vary the acoustic damping as a function of flow velocity. These modifications have limited success and the results indicate that a more sophisticated model is required to fully describe all (nonlinear) acoustic effects. However, the very good qualitative results show that the model adequately combines compressor and pipe system dynamics. Therefore, the proposed model forms a step forward in the analysis and modeling of surge in full-scale centrifugal compression systems and opens the path for further developments in this field.

Awareness that early cancer lump is painless could decrease breast cancer mortality in developing countries.

PubMed

Garg, Pankaj

2016-06-10

There are several factors which contribute to patients' reporting late to healthcare facility even after detecting the breast lump (patient delay). Amongst these, one of the important factors in low- and middle-income countries is lack of awareness that early cancer lump is painless (ECLIPs). Pain is often taken as a danger sign and absence of pain is often not taken seriously. The studies have shown that up to 98% of women in low-income countries are unaware that a painless lump could be a warning sign of early breast cancer. This fact is significant because this could be one of the prime reasons for the women having discovered a painless lump in the breast, accidentally or by breast self-examination, presume it to be harmless and don't report early to health care facility. Therefore, creating awareness about ECLIPs could be an effective strategy to reduce mortality due to breast cancer in low- and middle-income countries. Moreover, unlike modifying risk factors which requires long term behavior modification, creating awareness about ECLIPs is easy and cost effective.

Novel parametric reduced order model for aeroengine blade dynamics

NASA Astrophysics Data System (ADS)

Yuan, Jie; Allegri, Giuliano; Scarpa, Fabrizio; Rajasekaran, Ramesh; Patsias, Sophoclis

2015-10-01

The work introduces a novel reduced order model (ROM) technique to describe the dynamic behavior of turbofan aeroengine blades. We introduce an equivalent 3D frame model to describe the coupled flexural/torsional mode shapes, with their relevant natural frequencies and associated modal masses. The frame configurations are identified through a structural identification approach based on a simulated annealing algorithm with stochastic tunneling. The cost functions are constituted by linear combinations of relative errors associated to the resonance frequencies, the individual modal assurance criteria (MAC), and on either overall static or modal masses. When static masses are considered the optimized 3D frame can represent the blade dynamic behavior with an 8% error on the MAC, a 1% error on the associated modal frequencies and a 1% error on the overall static mass. When using modal masses in the cost function the performance of the ROM is similar, but the overall error increases to 7%. The approach proposed in this paper is considerably more accurate than state-of-the-art blade ROMs based on traditional Timoshenko beams, and provides excellent accuracy at reduced computational time when compared against high fidelity FE models. A sensitivity analysis shows that the proposed model can adequately predict the global trends of the variations of the natural frequencies when lumped masses are used for mistuning analysis. The proposed ROM also follows extremely closely the sensitivity of the high fidelity finite element models when the material parameters are used in the sensitivity.

A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

NASA Astrophysics Data System (ADS)

Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

2012-04-01

Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

Effect of shape on bone cement polymerization time in knee joint replacement surgery

PubMed Central

Yoon, Jung-Ro; Ko, Young-Rok; Shin, Young-Soo

2018-01-01

Abstract Background: Although many factors are known to influence the polymerization time of bone cement, it remains unclear which bone cement shape predicts the precise polymerization time. The purpose of this study was to investigate whether different cement shapes influenced polymerization time and to identify the relationship between cement shape and ambient operating theater temperature, relative humidity, and equilibration time. Methods: Samples were gathered prospectively from 237 patients undergoing primary total knee arthroplasty. The cement components were made into 2 different shapes: lump and pan. The time at which no macroscopic indentation of both cement models was possible was recorded as the polymerization time. Results: There was no significant difference between hand mixing (lump shape: 789.3 ± 128.4 seconds, P = .591; pan shape: 899.3 ± 152.2 seconds, P = .584) and vacuum mixing (lump shape: 780.2 ± 131.1 seconds, P = .591; pan shape: 909.9 ± 143.3 seconds, P = .584) in terms of polymerization time. Conversely, the polymerization time was significantly shorter for Antibiotic Simplex (lump shape: 757.4 ± 114.9 seconds, P = .001; pan shape: 879.5 ± 125.0 seconds, P < .001) when compared with Palacos R+G (lump shape: 829.0 ± 139.3 seconds, P = .001; pan shape: 942.9 ± 172.0 seconds, P < .001). Polymerization time was also significantly longer (P < .001) for the pan shape model (904 ± 148.0 seconds) when compared with the lump shape model (785.2 ± 129.4 seconds). In addition, the polymerization time decreased with increasing temperature (lump shape: R2 = 0.334, P < .001; pan shape: R2 = 0.375, P < .001), humidity (lump shape: R2 = 0.091, P < .001; pan shape: R2 = 0.106, P < .001), and equilibration time (lump shape: R2 = 0.073, P < .001; pan shape: R2 = 0.044, P < .001). Conclusions: The polymerization time was equally affected by temperature, relative humidity, and equilibration time regardless of bone cement shape. Furthermore, the pan shape model better reflected the cement polymerization time between implant and bone compared with the lump shape model. The current findings suggest that, clinically, constant pressure with the knee in <45° of flexion needs to be applied until remaining pan shaped cement is completely polymerized. PMID:29703041

7 CFR 1726.205 - Multiparty lump sum quotations.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Procurement Procedures § 1726.205 Multiparty lump sum quotations. The borrower or its engineer must contact a sufficient number of...

7 CFR 1726.205 - Multiparty lump sum quotations.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Procurement Procedures § 1726.205 Multiparty lump sum quotations. The borrower or its engineer must contact a sufficient number of...

7 CFR 1726.205 - Multiparty lump sum quotations.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Procurement Procedures § 1726.205 Multiparty lump sum quotations. The borrower or its engineer must contact a sufficient number of...

7 CFR 1726.205 - Multiparty lump sum quotations.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Procurement Procedures § 1726.205 Multiparty lump sum quotations. The borrower or its engineer must contact a sufficient number of...

7 CFR 1726.205 - Multiparty lump sum quotations.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Procurement Procedures § 1726.205 Multiparty lump sum quotations. The borrower or its engineer must contact a sufficient number of...

Breast Abscess Mimicking Breast Carcinoma in Male.

PubMed

Gochhait, Debasis; Dehuri, Priyadarshini; Umamahesweran, Sandyya; Kamat, Rohan

2018-01-01

Male breast can show almost all pathological entities described in female breast. Inflammatory conditions of the breast in male are not common; however, occasionally, it can be encountered in the form of an abscess. Clinically, gynecomastia always presents as a symmetric unilateral or bilateral lump in the retroareolar region, and any irregular asymmetric lump raises a possibility of malignancy. Radiology should be used as a part of the triple assessment protocol for breast lump along with fine-needle aspiration cytology for definite diagnosis and proper management.

Gravity controlled anti-reverse rotation device

DOEpatents

Dickinson, Robert J.; Wetherill, Todd M.

1983-01-01

A gravity assisted anti-reverse rotation device for preventing reverse rotation of pumps and the like. A horizontally mounted pawl is disposed to mesh with a fixed ratchet preventing reverse rotation when the pawl is advanced into intercourse with the ratchet by a vertically mounted lever having a lumped mass. Gravitation action on the lumped mass urges the pawl into mesh with the ratchet, while centrifugal force on the lumped mass during forward, allowed rotation retracts the pawl away from the ratchet.

Distributed and Lumped Parameter Models for the Characterization of High Throughput Bioreactors

PubMed Central

Conoscenti, Gioacchino; Cutrì, Elena; Tuan, Rocky S.; Raimondi, Manuela T.; Gottardi, Riccardo

2016-01-01

Next generation bioreactors are being developed to generate multiple human cell-based tissue analogs within the same fluidic system, to better recapitulate the complexity and interconnection of human physiology [1, 2]. The effective development of these devices requires a solid understanding of their interconnected fluidics, to predict the transport of nutrients and waste through the constructs and improve the design accordingly. In this work, we focus on a specific model of bioreactor, with multiple input/outputs, aimed at generating osteochondral constructs, i.e., a biphasic construct in which one side is cartilaginous in nature, while the other is osseous. We next develop a general computational approach to model the microfluidics of a multi-chamber, interconnected system that may be applied to human-on-chip devices. This objective requires overcoming several challenges at the level of computational modeling. The main one consists of addressing the multi-physics nature of the problem that combines free flow in channels with hindered flow in porous media. Fluid dynamics is also coupled with advection-diffusion-reaction equations that model the transport of biomolecules throughout the system and their interaction with living tissues and C constructs. Ultimately, we aim at providing a predictive approach useful for the general organ-on-chip community. To this end, we have developed a lumped parameter approach that allows us to analyze the behavior of multi-unit bioreactor systems with modest computational effort, provided that the behavior of a single unit can be fully characterized. PMID:27669413

Distributed and Lumped Parameter Models for the Characterization of High Throughput Bioreactors.

PubMed

Iannetti, Laura; D'Urso, Giovanna; Conoscenti, Gioacchino; Cutrì, Elena; Tuan, Rocky S; Raimondi, Manuela T; Gottardi, Riccardo; Zunino, Paolo

Next generation bioreactors are being developed to generate multiple human cell-based tissue analogs within the same fluidic system, to better recapitulate the complexity and interconnection of human physiology [1, 2]. The effective development of these devices requires a solid understanding of their interconnected fluidics, to predict the transport of nutrients and waste through the constructs and improve the design accordingly. In this work, we focus on a specific model of bioreactor, with multiple input/outputs, aimed at generating osteochondral constructs, i.e., a biphasic construct in which one side is cartilaginous in nature, while the other is osseous. We next develop a general computational approach to model the microfluidics of a multi-chamber, interconnected system that may be applied to human-on-chip devices. This objective requires overcoming several challenges at the level of computational modeling. The main one consists of addressing the multi-physics nature of the problem that combines free flow in channels with hindered flow in porous media. Fluid dynamics is also coupled with advection-diffusion-reaction equations that model the transport of biomolecules throughout the system and their interaction with living tissues and C constructs. Ultimately, we aim at providing a predictive approach useful for the general organ-on-chip community. To this end, we have developed a lumped parameter approach that allows us to analyze the behavior of multi-unit bioreactor systems with modest computational effort, provided that the behavior of a single unit can be fully characterized.

Current distribution in a three-dimensional IC analyzed by a perturbation method. Part 1: A simple steady state theory

NASA Technical Reports Server (NTRS)

Edmonds, Larry D.

1987-01-01

The steady state current distribution in a three dimensional integrated circuit is presented. A device physics approach, based on a perturbation method rather than an equivalent lumped circuit approach, is used. The perturbation method allows the various currents to be expressed in terms of elementary solutions which are solutions to very simple boundary value problems. A Simple Steady State Theory is the subtitle because the most obvious limitation of the present version of the analysis is that all depletion region boundary surfaces are treated as equipotential surfaces. This may be an adequate approximation in some applications but it is an obvious weakness in the theory when applied to latched states. Examples that illustrate the use of these analytical methods are not given because they will be presented in detail in the future.

Design and modeling of Faraday cages for substrate noise isolation

NASA Astrophysics Data System (ADS)

Wu, Joyce H.; del Alamo, Jesús A.

2013-07-01

A Faraday cage structure using through-substrate vias is an effective strategy to suppress substrate crosstalk, particularly at high frequencies. Faraday cages can reduce substrate noise by 32 dB at 10 GHz, and 26 dB at 50 GHz. We have developed lumped-element, equivalent circuit models of the Faraday cages and test structures to better understand the performance of the Faraday cages. These models compare well to measured results and show that the vias of the Faraday cage act as an RLC shunt to ground that draws substrate current. Designing a Faraday cage to achieve optimum isolation requires low via impedance and mitigation of via sidewall capacitance. The Faraday cage inductance is correlated to the number of vias and via spacing of the cage and can be optimized for the frequency of operation.

Development of dual-polarization LEKIDs for CMB observations

NASA Astrophysics Data System (ADS)

McCarrick, Heather; Abitbol, Maximilian H.; Ade, Peter A. R.; Barry, Peter; Bryan, Sean; Che, George; Day, Peter; Doyle, Simon; Flanigan, Daniel; Johnson, Bradley R.; Jones, Glenn; LeDuc, Henry G.; Limon, Michele; Mauskopf, Philip; Miller, Amber; Tucker, Carole; Zmuidzinas, Jonas

2016-07-01

We discuss the design considerations and initial measurements from arrays of dual-polarization, lumped-element kinetic inductance detectors (LEKIDs) nominally designed for cosmic microwave background (CMB) studies. The detectors are horn-coupled, and each array element contains two single-polarization LEKIDs, which are made from thin-film aluminum and optimized for a single spectral band centered on 150 GHz. We are developing two array architectures, one based on 160 micron thick silicon wafers and the other based on silicon-on-insulator (SOI) wafers with a 30 micron thick device layer. The 20-element test arrays (40 LEKIDs) are characterized with both a linearly-polarized electronic millimeter wave source and a thermal source. We present initial measurements including the noise spectra, noise-equivalent temperature, and responsivity. We discuss future testing and further design optimizations to be implemented.

Optomechanical oscillator pumped and probed by optically two isolated photonic crystal cavity systems.

PubMed

Tian, Feng; Sumikura, Hisashi; Kuramochi, Eiichi; Taniyama, Hideaki; Takiguchi, Masato; Notomi, Masaya

2016-11-28

Optomechanical control of on-chip emitters is an important topic related to integrated all-optical circuits. However, there is neither a realization nor a suitable optomechanical structure for this control. The biggest obstacle is that the emission signal can hardly be distinguished from the pump light because of the several orders' power difference. In this study, we designed and experimentally verified an optomechanical oscillation system, in which a lumped mechanical oscillator connected two optically isolated pairs of coupled one-dimensional photonic crystal cavities. As a functional device, the two pairs of coupled cavities were respectively used as an optomechanical pump for the lumped oscillator (cavity pair II, wavelengths were designed to be within a 1.5 μm band) and a modulation target of the lumped oscillator (cavity pair I, wavelengths were designed to be within a 1.2 μm band). By conducting finite element method simulations, we found that the lumped-oscillator-supported configurations of both cavity pairs enhance the optomechanical interactions, especially for higher order optical modes, compared with their respective conventional side-clamped configurations. Besides the desired first-order in-plane antiphase mechanical mode, other mechanical modes of the lumped oscillator were investigated and found to possibly have optomechanical applications with a versatile degree of freedom. In experiments, the oscillator's RF spectra were probed using both cavity pairs I and II, and the results matched those of the simulations. Dynamic detuning of the optical spectrum of cavity pair I was then implemented with a pumped lumped oscillator. This was the first demonstration of an optomechanical lumped oscillator connecting two optically isolated pairs of coupled cavities, whose biggest advantage is that one cavity pair can be modulated with an lumped oscillator without interference from the pump light in the other cavity pair. Thus, the oscillator is a suitable platform for optomechanical control of integrated lasers, cavity quantum electrodynamics, and spontaneous emission. Furthermore, this device may open the door on the study of interactions between photons, phonons, and excitons in the quantum regime.

Theoretical prediction on corrugated sandwich panels under bending loads

NASA Astrophysics Data System (ADS)

Shu, Chengfu; Hou, Shujuan

2018-05-01

In this paper, an aluminum corrugated sandwich panel with triangular core under bending loads was investigated. Firstly, the equivalent material parameters of the triangular corrugated core layer, which could be considered as an orthotropic panel, were obtained by using Castigliano's theorem and equivalent homogeneous model. Secondly, contributions of the corrugated core layer and two face panels were both considered to compute the equivalent material parameters of the whole structure through the classical lamination theory, and these equivalent material parameters were compared with finite element analysis solutions. Then, based on the Mindlin orthotropic plate theory, this study obtain the closed-form solutions of the displacement for a corrugated sandwich panel under bending loads in specified boundary conditions, and parameters study and comparison by the finite element method were executed simultaneously.

Review of Recent Development of Dynamic Wind Farm Equivalent Models Based on Big Data Mining

NASA Astrophysics Data System (ADS)

Wang, Chenggen; Zhou, Qian; Han, Mingzhe; Lv, Zhan’ao; Hou, Xiao; Zhao, Haoran; Bu, Jing

2018-04-01

Recently, the big data mining method has been applied in dynamic wind farm equivalent modeling. In this paper, its recent development with present research both domestic and overseas is reviewed. Firstly, the studies of wind speed prediction, equivalence and its distribution in the wind farm are concluded. Secondly, two typical approaches used in the big data mining method is introduced, respectively. For single wind turbine equivalent modeling, it focuses on how to choose and identify equivalent parameters. For multiple wind turbine equivalent modeling, the following three aspects are concentrated, i.e. aggregation of different wind turbine clusters, the parameters in the same cluster, and equivalence of collector system. Thirdly, an outlook on the development of dynamic wind farm equivalent models in the future is discussed.

Integrated Model of the Eye/Optic Nerve Head Biomechanical Environment

NASA Technical Reports Server (NTRS)

Ethier, C. R.; Feola, A.; Myers, J. G.; Nelson, E.; Raykin, J.; Samuels, B.

2017-01-01

Visual Impairment and Intracranial Pressure (VIIP) syndrome is a concern for long-duration space flight. Previously, it has been suggested that ocular changes observed in VIIP syndrome are related to the cephalad fluid shift that results in altered fluid pressures [1]. We are investigating the impact of changes in intracranial pressure (ICP) using a combination of numerical models, which simulate the effects of various environment conditions, including finite element (FE) models of the posterior eye. The specific interest is to understand how altered pressures due to gravitational changes affect the biomechanical environment of tissues of the posterior eye and optic nerve sheath. METHODS: Additional description of the numerical modeling is provided in the IWS abstract by Nelson et al. In brief, to simulate the effects of a cephalad fluid shift on the cardiovascular and ocular systems, we utilized a lumped-parameter compartment model of these systems. The outputs of this lumped-parameter model then inform boundary conditions (pressures) for a finite element model of the optic nerve head (Figure 1). As an example, we show here a simulation of postural change from supine to 15 degree head-down tilt (HDT), with primary outcomes being the predicted change in strains at the optic nerve head (ONH) region, specifically in the lamina cribrosa (LC), retrolaminar optic nerve, and prelaminar neural tissue (PLNT). The strain field can be decomposed into three orthogonal components, denoted as the first, second and third principal strains. We compare the peak tensile (first principal) and compressive (third principal) strains, since elevated strain alters cell phenotype and induces tissue remodeling. RESULTS AND CONCLUSIONS: Our lumped-parameter model predicted an IOP increase of c. 7 mmHg after 21 minutes of 15 degree HDT, which agreed with previous reports of IOP in HDT [1]. The corresponding FEM simulations predicted a relative increase in the magnitudes of the peak tensile and compressive strains in the lamina cribrosa of 42 and 43, respectively (Fig. 2). The corresponding changes in the optic nerve strains were 17 and 39, while in the PLNT they were 47 and 43. These magnitudes of relative elevations in peak strains may induce a phenotypic response in resident mechano-responsive resident cells [2]. This approach may be expanded to investigate other environmental changes (e.g. parabolic flight). Through our VIIP SCHOLAR project, we will validate and improve these integrated models by measuring patient-specific changes in optic nerve sheath geometry in patients with idiopathic intracranial hypertension before and after lumbar puncture and CSF removal.

Male Breast Cancer

MedlinePlus

Although breast cancer is much more common in women, men can get it too. It happens most often to men between ... 60 and 70. Breast lumps usually aren't cancer. However, most men with breast cancer have lumps. ...

Lump solutions to nonlinear partial differential equations via Hirota bilinear forms

NASA Astrophysics Data System (ADS)

Ma, Wen-Xiu; Zhou, Yuan

2018-02-01

Lump solutions are analytical rational function solutions localized in all directions in space. We analyze a class of lump solutions, generated from quadratic functions, to nonlinear partial differential equations. The basis of success is the Hirota bilinear formulation and the primary object is the class of positive multivariate quadratic functions. A complete determination of quadratic functions positive in space and time is given, and positive quadratic functions are characterized as sums of squares of linear functions. Necessary and sufficient conditions for positive quadratic functions to solve Hirota bilinear equations are presented, and such polynomial solutions yield lump solutions to nonlinear partial differential equations under the dependent variable transformations u = 2(ln ⁡ f) x and u = 2(ln ⁡ f) xx, where x is one spatial variable. Applications are made for a few generalized KP and BKP equations.

Artificial food lump from porous neoprene and the method of its use for the evaluation of adaptation patients to the dental constructions

NASA Astrophysics Data System (ADS)

Reshetnikov, A.; Urakov, A.; Kasatkin, A.; Soiher, M. G.; Kopylov, M.

2016-04-01

New dental product called artificial food lump is offered for dental practices. In its size and shape it is similar to the natural food bolus, which is formed in adult's mouth when chewing white bread. This innovative product resembles an inedible and non-swallowable chewing gum. Artificial lump is made of porous neoprene; it is elastic and has food flavor. It is not destroyed by chewing and has stable elasticity during chewing. Besides, artificial lump is manufactured in a way that it can be attached to the patient's clothes with a braid line. New medical device is intended to create the masticatory loading in patients' mouth in order to evaluate the quality of mounted dental restorations as well as patient's adaptation to it during the chewing process.

Outbreak of primary inoculation tuberculosis in an acupuncture clinic in southeastern China.

PubMed

Wang, J; Zhu, M Y; Li, C; Zhang, H B; Zuo, G B; Wang, M H; Teng, H L

2015-04-01

Outbreak of Mycobacterium tuberculosis infections associated with acupuncture has not been reported. Thirteen patients with a painful swollen lump were referred to our hospital. The index patient received acupuncture and paraspinal muscular injection at a local acupuncture clinic in April 2011 and was diagnosed with M. tuberculosis 1 month later. From May 2011 to August 2011, 12 more patients with a swollen lump on the nuchal region or in the lower back or the buttocks region were referred to our hospital. Tuberculin skin test (TST), T-SPOT.TB, acid-fast stain, M. tuberculosis culture, chest radiograph, and lump magnetic resonance imaging (MRI) were performed and the patients were diagnosed with tuberculous abscess of the lump. All 13 patients received intramuscular injection at the paraspinal muscle by two acupuncturists at a local clinic and reported a swollen lump at the injection site. The needles and syringes were reused after autoclave sterilization. The TST was positive in all patients. Twelve patients had positive acid-fast stains. Mycobacterial cultures of abscess specimens were positive in all 13 patients. T-SPOT.TB tests were positive in all patients who underwent the test. The lesions and biopsies were subjected to polymerase chain reaction (PCR) and gene sequencing by the Disease Control Center of Zhejiang Province, China and the causative agent was identified as M. tuberculosis, Beijing type. In conclusion, physicians should consider the possibility of mycobacterial infections, apart from other bacterial agents, in patients with a swollen paraspinal lump following intramuscular injection.

Thermal modeling of a cryogenic turbopump for space shuttle applications.

NASA Technical Reports Server (NTRS)

Knowles, P. J.

1971-01-01

Thermal modeling of a cryogenic pump and a hot-gas turbine in a turbopump assembly proposed for the Space Shuttle is described in this paper. A model, developed by identifying the heat-transfer regimes and incorporating their dependencies into a turbopump system model, included heat transfer for two-phase cryogen, hot-gas (200 R) impingement on turbine blades, gas impingement on rotating disks and parallel plate fluid flow. The ?thermal analyzer' program employed to develop this model was the TRW Systems Improved Numerical Differencing Analyzer (SINDA). This program uses finite differencing with lumped parameter representation for each node. Also discussed are model development, simulations of turbopump startup/shutdown operations, and the effects of varying turbopump parameters on the thermal performance.

A distributed lumped active all-pass network configuration.

NASA Technical Reports Server (NTRS)

Huelsman, L. P.; Raghunath, S.

1972-01-01

In this correspondence a new and interesting distributed lumped active network configuration that realizes an all-pass network function is described. A design chart for determining the values of the network elements is included.

Modeling of two-hot-arm horizontal thermal actuator

NASA Astrophysics Data System (ADS)

Yan, Dong; Khajepour, Amir; Mansour, Raafat

2003-03-01

Electrothermal actuators have a very promising future in MEMS applications since they can generate large deflection and force with low actuating voltages and small device areas. In this study, a lumped model of a two-hot-arm horizontal thermal actuator is presented. In order to prove the accuracy of the lumped model, finite element analysis (FEA) and experimental results are provided. The two-hot-arm thermal actuator has been fabricated using the MUMPs process. Both the experimental and FEA results are in good agreement with the results of lumped modeling.

Electrical Lumped Model Examination for Load Variation of Circulation System

NASA Astrophysics Data System (ADS)

Koya, Yoshiharu; Ito, Mitsuyo; Mizoshiri, Isao

Modeling and analysis of the circulation system enables the characteristic decision of circulation system in the body to be made. So, many models of circulation system have been proposed. But, they are complicated because the models include a lot of elements. Therefore, we proposed a complete circulation model as a lumped electrical circuit, which is comparatively simple. In this paper, we examine the effectiveness of the complete circulation model as a lumped electrical circuit. We use normal, angina pectoris, dilated cardiomyopathy and myocardial infarction for evaluation of the ventricular contraction function.

Brine evolution and mineral deposition in hydrologically open evaporite basins

USGS Publications Warehouse

Sanford, W.E.; Wood, W.W.

1991-01-01

A lumped-parameter, solute mass-balance model is developed to define the role of water outflow from a well-mixed basin. A mass-balance model is analyzed with a geochemical model designed for waters with high ionic strengths. Two typical waters, seawater and a Na-HCO3 ground water, are analyzed to illustrate the control that the leakage ratio (or hydrologic openness of the basin) has on brine evolution and the suite and thicknesses of evaporite minerals deposited. The analysis suggests that brines evolve differently under different leakage conditions. -from Authors

On the Discrete Spectrum of the Nonstationary Schrödinger Equation and Multipole Lumps of the Kadomtsev-Petviashvili I Equation

NASA Astrophysics Data System (ADS)

Villarroel, Javier; Ablowitz, Mark J.

The discrete spectrum of the nonstationary Schrödinger equation and localized solutions of the Kadomtsev-Petviashvili-I (KPI) equation are studied via the inverse scattering transform. It is shown that there exist infinitely many real and rationally decaying potentials which correspond to a discrete spectrum whose related eigenfunctions have multiple poles in the spectral parameter. An index or winding number is asssociated with each of these solutions. The resulting localized solutions of KPI behave as collection of individual humps with nonuniform dynamics.

The NASTRAN user's manual (level 17.0)

NASA Technical Reports Server (NTRS)

1979-01-01

NASTRAN embodies a lumped element approach, wherein the distributed physical properties of a structure are represented by a model consisting of a finite number of idealized substructures or elements that are interconnected at a finite of grid points, to which loads are applied. All input and output data pertain to the idealized structural model. The general procedures for defining structural models are described and instructions are given for each of the bulk data cards and case control cards. Additional information on the case control cards and use of parameters is included for each rigid format.

Blade frequency program for nonuniform helicopter rotors, with automated frequency search

NASA Technical Reports Server (NTRS)

Sadler, S. G.

1972-01-01

A computer program for determining the natural frequencies and normal modes of a lumped parameter model of a rotating, twisted beam, with nonuniform mass and elastic properties was developed. The program is used to solve the conditions existing in a helicopter rotor where the outboard end of the rotor has zero forces and moments. Three frequency search methods have been implemented. Including an automatic search technique, which allows the program to find up to the fifteen lowest natural frequencies without the necessity for input estimates of these frequencies.

Advanced Numerical Methods for Simulating Nonlinear Multirate Lumped Parameter Models

DTIC Science & Technology

1991-05-01

defining a Waveform: typedef struct Waveform char *name; /* character string of the name of the variable */ double tn; /* time of the beginning of the...A State-Space Approach, Reprinted from Proc. Third Ann. Allerton Conf. Circuits and Systems Thoery , 659-668, in Computer-Aided Circuit Design...kg/n 3) 1025.9 kg/m3 @ 15* C. v Kinematic Viscosity of Water (m2/sec) 1.19x10-6 m2/sec @ 15* C. G Acceleration of Gravity (m/sec2) 9.80665 m/sec 2 L

Rogue waves in the multicomponent Mel'nikov system and multicomponent Schrödinger-Boussinesq system

NASA Astrophysics Data System (ADS)

Sun, Baonan; Lian, Zhan

2018-02-01

By virtue of the bilinear method and the KP hierarchy reduction technique, exact explicit rational solutions of the multicomponent Mel'nikov equation and the multicomponent Schrödinger-Boussinesq equation are constructed, which contain multicomponent short waves and single-component long wave. For the multicomponent Mel'nikov equation, the fundamental rational solutions possess two different behaviours: lump and rogue wave. It is shown that the fundamental (simplest) rogue waves are line localised waves which arise from the constant background with a line profile and then disappear into the constant background again. The fundamental line rogue waves can be classified into three: bright, intermediate and dark line rogue waves. Two subclasses of non-fundamental rogue waves, i.e., multirogue waves and higher-order rogue waves are discussed. The multirogue waves describe interaction of several fundamental line rogue waves, in which interesting wave patterns appear in the intermediate time. Higher-order rogue waves exhibit dynamic behaviours that the wave structures start from lump and then retreat back to it. Moreover, by taking the parameter constraints further, general higher-order rogue wave solutions for the multicomponent Schrödinger-Boussinesq system are generated.

Frequency Combs in a Lumped-Element Josephson-Junction Circuit

NASA Astrophysics Data System (ADS)

Khan, Saeed; Türeci, Hakan E.

2018-04-01

We investigate the dynamics of a microwave-driven Josephson junction capacitively coupled to a lumped-element L C oscillator. In the regime of driving where the Josephson junction can be approximated as a Kerr oscillator, this minimal nonlinear system has been previously shown to exhibit a bistability in phase and amplitude. In the present study, we characterize the full phase diagram and show that besides a parameter regime exhibiting bistability, there is also a regime of self-oscillations characterized by a frequency comb in its spectrum. We discuss the mechanism of comb generation which appears to be different from those studied in microcavity frequency combs and mode-locked lasers. We then address the fate of the comblike spectrum in the regime of strong quantum fluctuations, reached when nonlinearity becomes the dominant scale with respect to dissipation. We find that the nonlinearity responsible for the emergence of the frequency combs also leads to its dephasing, leading to broadening and ultimate disappearance of sharp spectral peaks. Our study explores the fundamental question of the impact of quantum fluctuations for quantum systems which do not possess a stable fixed point in the classical limit.

Stage-by-Stage and Parallel Flow Path Compressor Modeling for a Variable Cycle Engine, NASA Advanced Air Vehicles Program - Commercial Supersonic Technology Project - AeroServoElasticity

NASA Technical Reports Server (NTRS)

Kopasakis, George; Connolly, Joseph W.; Cheng, Larry

2015-01-01

This paper covers the development of stage-by-stage and parallel flow path compressor modeling approaches for a Variable Cycle Engine. The stage-by-stage compressor modeling approach is an extension of a technique for lumped volume dynamics and performance characteristic modeling. It was developed to improve the accuracy of axial compressor dynamics over lumped volume dynamics modeling. The stage-by-stage compressor model presented here is formulated into a parallel flow path model that includes both axial and rotational dynamics. This is done to enable the study of compressor and propulsion system dynamic performance under flow distortion conditions. The approaches utilized here are generic and should be applicable for the modeling of any axial flow compressor design accurate time domain simulations. The objective of this work is as follows. Given the parameters describing the conditions of atmospheric disturbances, and utilizing the derived formulations, directly compute the transfer function poles and zeros describing these disturbances for acoustic velocity, temperature, pressure, and density. Time domain simulations of representative atmospheric turbulence can then be developed by utilizing these computed transfer functions together with the disturbance frequencies of interest.

46 CFR 148.245 - Direct reduced iron (DRI); lumps, pellets, and cold-molded briquettes.

Code of Federal Regulations, 2011 CFR

2011-10-01

... another during periods of rain or snow. (e) DRI lumps, pellets, or cold-molded briquettes may not be... percent hydrogen, by volume, is maintained throughout the voyage in any hold containing these materials...

Potential for Remotely Sensed Soil Moisture Data in Hydrologic Modeling

NASA Technical Reports Server (NTRS)

Engman, Edwin T.

1997-01-01

Many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture and portray the spatial heterogeneity of hydrologic processes and properties that one encounters in drainage basins. The hydrologic processes that may be detected include ground water recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential ET, and information about the hydrologic properties of soils and heterogeneity of hydrologic parameters. Microwave remote sensing has the potential to detect these signatures within a basin in the form of volumetric soil moisture measurements in the top few cm. These signatures should provide information on how and where to apply soil physical parameters in distributed and lumped parameter models and how to subdivide drainage basins into hydrologically similar sub-basins.

Biomass viability: An experimental study and the development of an empirical mathematical model for submerged membrane bioreactor.

PubMed

Zuthi, M F R; Ngo, H H; Guo, W S; Nghiem, L D; Hai, F I; Xia, S Q; Zhang, Z Q; Li, J X

2015-08-01

This study investigates the influence of key biomass parameters on specific oxygen uptake rate (SOUR) in a sponge submerged membrane bioreactor (SSMBR) to develop mathematical models of biomass viability. Extra-cellular polymeric substances (EPS) were considered as a lumped parameter of bound EPS (bEPS) and soluble microbial products (SMP). Statistical analyses of experimental results indicate that the bEPS, SMP, mixed liquor suspended solids and volatile suspended solids (MLSS and MLVSS) have functional relationships with SOUR and their relative influence on SOUR was in the order of EPS>bEPS>SMP>MLVSS/MLSS. Based on correlations among biomass parameters and SOUR, two independent empirical models of biomass viability were developed. The models were validated using results of the SSMBR. However, further validation of the models for different operating conditions is suggested. Copyright © 2015 Elsevier Ltd. All rights reserved.

Engineering Inertial and Primary-Frequency Response for Distributed Energy Resources: Preprint

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

Dall-Anese, Emiliano; Zhao, Changhong; Guggilam, Swaroop

We propose a framework to engineer synthetic-inertia and droop-control parameters for distributed energy resources (DERs) so that the system frequency in a network composed of DERs and synchronous generators conforms to prescribed transient and steady-state performance specifications. Our approach is grounded in a second-order lumped-parameter model that captures the dynamics of synchronous generators and frequency-responsive DERs endowed with inertial and droop control. A key feature of this reduced-order model is that its parameters can be related to those of the originating higher-order dynamical model. This allows one to systematically design the DER inertial and droop-control coefficients leveraging classical frequency-domain responsemore » characteristics of second-order systems. Time-domain simulations validate the accuracy of the model-reduction method and demonstrate how DER controllers can be designed to meet steady-state-regulation and transient-performance specifications.« less

Engineering Inertial and Primary-Frequency Response for Distributed Energy Resources

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

Dall-Anese, Emiliano; Zhao, Changhong; Guggilam, Swaroop

We propose a framework to engineer synthetic-inertia and droop-control parameters for distributed energy resources (DERs) so that the system frequency in a network composed of DERs and synchronous generators conforms to prescribed transient and steady-state performance specifications. Our approach is grounded in a second-order lumped-parameter model that captures the dynamics of synchronous generators and frequency-responsive DERs endowed with inertial and droop control. A key feature of this reduced-order model is that its parameters can be related to those of the originating higherorder dynamical model. This allows one to systematically design the DER inertial and droop-control coefficients leveraging classical frequency-domain responsemore » characteristics of second-order systems. Time-domain simulations validate the accuracy of the model-reduction method and demonstrate how DER controllers can be designed to meet steady-state-regulation and transient-performance specifications.« less

A Variational Reduction and the Existence of a Fully Localised Solitary Wave for the Three-Dimensional Water-Wave Problem with Weak Surface Tension

NASA Astrophysics Data System (ADS)

Buffoni, Boris; Groves, Mark D.; Wahlén, Erik

2017-12-01

Fully localised solitary waves are travelling-wave solutions of the three- dimensional gravity-capillary water wave problem which decay to zero in every horizontal spatial direction. Their existence has been predicted on the basis of numerical simulations and model equations (in which context they are usually referred to as `lumps'), and a mathematically rigorous existence theory for strong surface tension (Bond number {β} greater than {1/3} ) has recently been given. In this article we present an existence theory for the physically more realistic case {0 < β < 1/3} . A classical variational principle for fully localised solitary waves is reduced to a locally equivalent variational principle featuring a perturbation of the functional associated with the Davey-Stewartson equation. A nontrivial critical point of the reduced functional is found by minimising it over its natural constraint set.

A Variational Reduction and the Existence of a Fully Localised Solitary Wave for the Three-Dimensional Water-Wave Problem with Weak Surface Tension

NASA Astrophysics Data System (ADS)

Buffoni, Boris; Groves, Mark D.; Wahlén, Erik

2018-06-01

Fully localised solitary waves are travelling-wave solutions of the three- dimensional gravity-capillary water wave problem which decay to zero in every horizontal spatial direction. Their existence has been predicted on the basis of numerical simulations and model equations (in which context they are usually referred to as `lumps'), and a mathematically rigorous existence theory for strong surface tension (Bond number {β} greater than {1/3}) has recently been given. In this article we present an existence theory for the physically more realistic case {0 < β < 1/3}. A classical variational principle for fully localised solitary waves is reduced to a locally equivalent variational principle featuring a perturbation of the functional associated with the Davey-Stewartson equation. A nontrivial critical point of the reduced functional is found by minimising it over its natural constraint set.

SPICE modelling of a coupled piezoelectric-bimetal heat engine for autonomous Wireless Sensor Nodes (WSN) power supply

NASA Astrophysics Data System (ADS)

Boughaleb, J.; Monfray, S.; Vine, G.; Cottinet, P. J.; Arnaud, A.; Boisseau, S.; Duret, A. B.; Quenard, S.; Puscasu, O.; Maitre, C.; Trochut, S.; Hasbani, F.; Di Gilio, T.; Heinrich, V.; Urard, P.; Grasset, J. C.; Boeuf, F.; Guyomar, D.; Skotnicki, T.

2014-11-01

This paper deals with an electrical modelling and optimization of a thermal energy harvester dedicated to power autonomous systems. Such devices based on bimetal strips and piezoceramics turn thermal gradients into electricity by a two-step conversion mechanism. This work focuses first on a demonstration of a ST-WSN (GreenNet demonstration platform) supplied by the harvester to validate, for the first time, the harvesters viability. That demonstration focuses attention on the need for an optimized power management circuit for piezoelectric generators able to reach output voltages up to 20 V. The work deals then with the proposal of an equivalent lumped element model of the piezoelectric transducer with its SPICE implementation to enable the optimization of a dedicated power management circuit based on the Pulsed Synchronous Charge Extractor (PSCE). Simulations using the SPICE model and the power management circuit lead to an increased extracted power by 144%.

Uncovering the effective interval of resolution parameter across multiple community optimization measures

NASA Astrophysics Data System (ADS)

Li, Hui-Jia; Cheng, Qing; Mao, He-Jin; Wang, Huanian; Chen, Junhua

2017-03-01

The study of community structure is a primary focus of network analysis, which has attracted a large amount of attention. In this paper, we focus on two famous functions, i.e., the Hamiltonian function H and the modularity density measure D, and intend to uncover the effective thresholds of their corresponding resolution parameter γ without resolution limit problem. Two widely used example networks are employed, including the ring network of lumps as well as the ad hoc network. In these two networks, we use discrete convex analysis to study the interval of resolution parameter of H and D that will not cause the misidentification. By comparison, we find that in both examples, for Hamiltonian function H, the larger the value of resolution parameter γ, the less resolution limit the network suffers; while for modularity density D, the less resolution limit the network suffers when we decrease the value of γ. Our framework is mathematically strict and efficient and can be applied in a lot of scientific fields.

HEART: an automated beat-to-beat cardiovascular analysis package using Matlab.

PubMed

Schroeder, M J Mark J; Perreault, Bill; Ewert, D L Daniel L; Koenig, S C Steven C

2004-07-01

A computer program is described for beat-to-beat analysis of cardiovascular parameters from high-fidelity pressure and flow waveforms. The Hemodynamic Estimation and Analysis Research Tool (HEART) is a post-processing analysis software package developed in Matlab that enables scientists and clinicians to document, load, view, calibrate, and analyze experimental data that have been digitally saved in ascii or binary format. Analysis routines include traditional hemodynamic parameter estimates as well as more sophisticated analyses such as lumped arterial model parameter estimation and vascular impedance frequency spectra. Cardiovascular parameter values of all analyzed beats can be viewed and statistically analyzed. An attractive feature of the HEART program is the ability to analyze data with visual quality assurance throughout the process, thus establishing a framework toward which Good Laboratory Practice (GLP) compliance can be obtained. Additionally, the development of HEART on the Matlab platform provides users with the flexibility to adapt or create study specific analysis files according to their specific needs. Copyright 2003 Elsevier Ltd.

Reduction of chemical reaction models

NASA Technical Reports Server (NTRS)

Frenklach, Michael

1991-01-01

An attempt is made to reconcile the different terminologies pertaining to reduction of chemical reaction models. The approaches considered include global modeling, response modeling, detailed reduction, chemical lumping, and statistical lumping. The advantages and drawbacks of each of these methods are pointed out.

Lump Solitons in Surface Tension Dominated Flows

NASA Astrophysics Data System (ADS)

Milewski, Paul; Berger, Kurt

1999-11-01

The Kadomtsev-Petviashvilli I equation (KPI) which models small-amplitude, weakly three-dimensional surface-tension dominated long waves is integrable and allows for algebraically decaying lump solitary waves. It is not known (theoretically or numerically) whether the full free-surface Euler equations support such solutions. We consider an intermediate model, the generalised Benney-Luke equation (gBL) which is isotropic (not weakly three-dimensional) and contains KPI as a limit. We show numerically that: 1. gBL supports lump solitary waves; 2. These waves collide elastically and are stable; 3. They are generated by resonant flow over an obstacle.

Design synthesis and optimization of permanent magnet synchronous machines based on computationally-efficient finite element analysis

NASA Astrophysics Data System (ADS)

Sizov, Gennadi Y.

In this dissertation, a model-based multi-objective optimal design of permanent magnet ac machines, supplied by sine-wave current regulated drives, is developed and implemented. The design procedure uses an efficient electromagnetic finite element-based solver to accurately model nonlinear material properties and complex geometric shapes associated with magnetic circuit design. Application of an electromagnetic finite element-based solver allows for accurate computation of intricate performance parameters and characteristics. The first contribution of this dissertation is the development of a rapid computational method that allows accurate and efficient exploration of large multi-dimensional design spaces in search of optimum design(s). The computationally efficient finite element-based approach developed in this work provides a framework of tools that allow rapid analysis of synchronous electric machines operating under steady-state conditions. In the developed modeling approach, major steady-state performance parameters such as, winding flux linkages and voltages, average, cogging and ripple torques, stator core flux densities, core losses, efficiencies and saturated machine winding inductances, are calculated with minimum computational effort. In addition, the method includes means for rapid estimation of distributed stator forces and three-dimensional effects of stator and/or rotor skew on the performance of the machine. The second contribution of this dissertation is the development of the design synthesis and optimization method based on a differential evolution algorithm. The approach relies on the developed finite element-based modeling method for electromagnetic analysis and is able to tackle large-scale multi-objective design problems using modest computational resources. Overall, computational time savings of up to two orders of magnitude are achievable, when compared to current and prevalent state-of-the-art methods. These computational savings allow one to expand the optimization problem to achieve more complex and comprehensive design objectives. The method is used in the design process of several interior permanent magnet industrial motors. The presented case studies demonstrate that the developed finite element-based approach practically eliminates the need for using less accurate analytical and lumped parameter equivalent circuit models for electric machine design optimization. The design process and experimental validation of the case-study machines are detailed in the dissertation.

Distributed snow modeling suitable for use with operational data for the American River watershed.

NASA Astrophysics Data System (ADS)

Shamir, E.; Georgakakos, K. P.

2004-12-01

The mountainous terrain of the American River watershed (~4300 km2) at the Western slope of the Northern Sierra Nevada is subject to significant variability in the atmospheric forcing that controls the snow accumulation and ablations processes (i.e., precipitation, surface temperature, and radiation). For a hydrologic model that attempts to predict both short- and long-term streamflow discharges, a plausible description of the seasonal and intermittent winter snow pack accumulation and ablation is crucial. At present the NWS-CNRFC operational snow model is implemented in a semi distributed manner (modeling unit of about 100-1000 km2) and therefore lump distinct spatial variability of snow processes. In this study we attempt to account for the precipitation, temperature, and radiation spatial variability by constructing a distributed snow accumulation and melting model suitable for use with commonly available sparse data. An adaptation of the NWS-Snow17 energy and mass balance that is used operationally at the NWS River Forecast Centers is implemented at 1 km2 grid cells with distributed input and model parameters. The input to the model (i.e., precipitation and surface temperature) is interpolated from observed point data. The surface temperature was interpolated over the basin based on adiabatic lapse rates using topographic information whereas the precipitation was interpolated based on maps of climatic mean annual rainfall distribution acquired from PRISM. The model parameters that control the melting rate due to radiation were interpolated based on aspect. The study was conducted for the entire American basin for the snow seasons of 1999-2000. Validation of the Snow Water Equivalent (SWE) prediction is done by comparing to observation from 12 snow Sensors. The Snow Cover Area (SCA) prediction was evaluated by comparing to remotely sensed 500m daily snow cover derived from MODIS. The results that the distribution of snow over the area is well captured and the quantity compared to the snow gauges are well estimated in the high elevation.

FIDDLE: A Computer Code for Finite Difference Development of Linear Elasticity in Generalized Curvilinear Coordinates

NASA Technical Reports Server (NTRS)

Kaul, Upender K.

2005-01-01

A three-dimensional numerical solver based on finite-difference solution of three-dimensional elastodynamic equations in generalized curvilinear coordinates has been developed and used to generate data such as radial and tangential stresses over various gear component geometries under rotation. The geometries considered are an annulus, a thin annular disk, and a thin solid disk. The solution is based on first principles and does not involve lumped parameter or distributed parameter systems approach. The elastodynamic equations in the velocity-stress formulation that are considered here have been used in the solution of problems of geophysics where non-rotating Cartesian grids are considered. For arbitrary geometries, these equations along with the appropriate boundary conditions have been cast in generalized curvilinear coordinates in the present study.

Inhalation Exposure to PM-Bound Polycyclic Aromatic Hydrocarbons Released from Barbecue Grills Powered by Gas, Lump Charcoal, and Charcoal Briquettes.

PubMed

Badyda, Artur J; Widziewicz, Kamila; Rogula-Kozłowska, Wioletta; Majewski, Grzegorz; Jureczko, Izabela

2018-01-01

The present study seeks to define the possible cancer risk arising from the inhalation exposure to particle (PM)-bound polycyclic aromatic hydrocarbons (PAHs) present in barbecue emission gases and to compare the risk depending on the type of fuel used for grill powering. Three types of fuel were compared: liquid propane gas, lump charcoal, and charcoal briquettes. PM 2.5 and PM 2.5-100 were collected during grilling. Subsequently, 16 PAHs congeners were extracted from the PM samples and measured quantitatively using gas chromatography. The content of PM-bound PAHs was used to calculate PAHs deposition in the respiratory tract using the multiple path particle dosimetry model. Finally, a probabilistic risk model was developed to assess the incremental lifetime cancer risk (ILCR) faced by people exposed to PAHs. We found a distinctly greater PAHs formation in case of grills powered by charcoal briquettes. The summary concentration of PAHs (Σ16PAH) ranged from <0.002 μg/m 3 (gas grill) to 21.52 μg/m 3 (grill powered by briquettes). Daily exposure of a grill operator, while grilling meat, to PM 2.5 -bound PAHs, adjusted to benzo[a]pyrene toxicity equivalent (BaP eq ), was 326.9, 401.6, and 0.04 ng/d for lump charcoal, charcoal briquettes, and gas powered grill, respectively. Exposure to PAHs emitted from charcoal briquettes was four orders of magnitude greater than that for gas grill. The ILCR followed a log-normal distribution, with a geometric mean of 8.38 × 10 -5 for exposure to PM 2.5 -bound PAHs emitted from gas grills unloaded with food and as high as 8.68 × 10 -1 for the grills loaded with food over charcoal briquettes. The estimated cancer risk for people who would inhale barbecue particles for 5 h a day, 40 days a year exceeds the acceptable level set by the U.S. Environmental Protection Agency. We conclude that the type of heat source used for grilling influences the PM-bound PAHs formation. The greatest concentration of PAHs is generated when grilling over charcoal briquettes. Loading grills with food generates conspicuously more PAHs emissions. Traditional grilling poses cancer risk much above the acceptable limit, as opposed to much less risk involving gas powered grills.

Symbolic computation of equivalence transformations and parameter reduction for nonlinear physical models

NASA Astrophysics Data System (ADS)

Cheviakov, Alexei F.

2017-11-01

An efficient systematic procedure is provided for symbolic computation of Lie groups of equivalence transformations and generalized equivalence transformations of systems of differential equations that contain arbitrary elements (arbitrary functions and/or arbitrary constant parameters), using the software package GeM for Maple. Application of equivalence transformations to the reduction of the number of arbitrary elements in a given system of equations is discussed, and several examples are considered. The first computational example of generalized equivalence transformations where the transformation of the dependent variable involves an arbitrary constitutive function is presented. As a detailed physical example, a three-parameter family of nonlinear wave equations describing finite anti-plane shear displacements of an incompressible hyperelastic fiber-reinforced medium is considered. Equivalence transformations are computed and employed to radically simplify the model for an arbitrary fiber direction, invertibly reducing the model to a simple form that corresponds to a special fiber direction, and involves no arbitrary elements. The presented computation algorithm is applicable to wide classes of systems of differential equations containing arbitrary elements.

Experimental Verification of Guided-Wave Lumped Circuits Using Waveguide Metamaterials

NASA Astrophysics Data System (ADS)

Li, Yue; Zhang, Zhijun

2018-04-01

Through the construction and characterization in microwave frequencies, we experimentally demonstrate our recently developed theory of waveguide lumped circuits, i.e., waveguide metatronics [Sci. Adv. 2, e1501790 (2016), 10.1126/sciadv.1501790], as a method to design subwavelength-scaled analog circuits. In the paradigm of waveguide metatronics, numbers of lumped inductors and capacitors are easily integrated functionally inside the waveguide, which is an irreplaceable transmission line in millimeter-wave and terahertz systems with the advantages of low radiation loss and low crosstalk. An example of multiple-ordered metatronic filters with layered structures is fabricated utilizing the technique of substrate integrated waveguides, which can be easily constructed by the printed-circuit-board process. The materials used in the construction are also typical microwave materials with positive permittivity, low loss, and negligible dispersion, imitating the plasmonic materials with negative permittivity in the optical domain. The results verify the theory of waveguide metatronics, which provides an efficient platform of functional lumped circuit design for guided-wave processing.

Analytic study of solutions for a (3 + 1) -dimensional generalized KP equation

NASA Astrophysics Data System (ADS)

Gao, Hui; Cheng, Wenguang; Xu, Tianzhou; Wang, Gangwei

2018-03-01

The (3 + 1) -dimensional generalized KP (gKP) equation is an important nonlinear partial differential equation in theoretical and mathematical physics which can be used to describe nonlinear wave motion. Through the Hirota bilinear method, one-solition, two-solition and N-solition solutions are derived via symbolic computation. Two classes of lump solutions, rationally localized in all directions in space, to the dimensionally reduced cases in (2 + 1)-dimensions, are constructed by using a direct method based on the Hirota bilinear form of the equation. It implies that we can derive the lump solutions of the reduced gKP equation from positive quadratic function solutions to the aforementioned bilinear equation. Meanwhile, we get interaction solutions between a lump and a kink of the gKP equation. The lump appears from a kink and is swallowed by it with the change of time. This work offers a possibility which can enrich the variety of the dynamical features of solutions for higher-dimensional nonlinear evolution equations.

Suspension parameter estimation in the frequency domain using a matrix inversion approach

NASA Astrophysics Data System (ADS)

Thite, A. N.; Banvidi, S.; Ibicek, T.; Bennett, L.

2011-12-01

The dynamic lumped parameter models used to optimise the ride and handling of a vehicle require base values of the suspension parameters. These parameters are generally experimentally identified. The accuracy of identified parameters can depend on the measurement noise and the validity of the model used. The existing publications on suspension parameter identification are generally based on the time domain and use a limited degree of freedom. Further, the data used are either from a simulated 'experiment' or from a laboratory test on an idealised quarter or a half-car model. In this paper, a method is developed in the frequency domain which effectively accounts for the measurement noise. Additional dynamic constraining equations are incorporated and the proposed formulation results in a matrix inversion approach. The nonlinearities in damping are estimated, however, using a time-domain approach. Full-scale 4-post rig test data of a vehicle are used. The variations in the results are discussed using the modal resonant behaviour. Further, a method is implemented to show how the results can be improved when the matrix inverted is ill-conditioned. The case study shows a good agreement between the estimates based on the proposed frequency-domain approach and measurable physical parameters.

Online Condition Monitoring of Gripper Cylinder in TBM Based on EMD Method

NASA Astrophysics Data System (ADS)

Li, Lin; Tao, Jian-Feng; Yu, Hai-Dong; Huang, Yi-Xiang; Liu, Cheng-Liang

2017-11-01

The gripper cylinder that provides braced force for Tunnel Boring Machine (TBM) might fail due to severe vibration when the TBM excavates in the tunnel. Early fault diagnosis of the gripper cylinder is important for the safety and efficiency of the whole tunneling project. In this paper, an online condition monitoring system based on the Empirical Mode Decomposition (EMD) method is established for fault diagnosis of the gripper cylinder while TBM is working. Firstly, the lumped mass parameter model of the gripper cylinder is established considering the influence of the variable stiffness at the rock interface, the equivalent stiffness of the oil, the seals, and the copper guide sleeve. The dynamic performance of the gripper cylinder is investigated to provide basis for its health condition evaluation. Then, the EMD method is applied to identify the characteristic frequencies of the gripper cylinder for fault diagnosis and a field test is used to verify the accuracy of the EMD method for detection of the characteristic frequencies. Furthermore, the contact stiffness at the interface between the barrel and the rod is calculated with Hertz theory and the relationship between the natural frequency and the stiffness varying with the health condition of the cylinder is simulated based on the dynamic model. The simulation shows that the characteristic frequencies decrease with the increasing clearance between the barrel and the rod, thus the defects could be indicated by monitoring the natural frequency. Finally, a health condition management system of the gripper cylinder based on the vibration signal and the EMD method is established, which could ensure the safety of TBM.

Numerical and analytical investigation towards performance enhancement of a newly developed rockfall protective cable-net structure

NASA Astrophysics Data System (ADS)

Dhakal, S.; Bhandary, N. P.; Yatabe, R.; Kinoshita, N.

2012-04-01

In a previous companion paper, we presented a three-tier modelling of a particular type of rockfall protective cable-net structure (barrier), developed newly in Japan. Therein, we developed a three-dimensional, Finite Element based, nonlinear numerical model having been calibrated/back-calculated and verified with the element- and structure-level physical tests. Moreover, using a very simple, lumped-mass, single-degree-of-freedom, equivalently linear analytical model, a global-displacement-predictive correlation was devised by modifying the basic equation - obtained by combining the principles of conservation of linear momentum and energy - based on the back-analysis of the tests on the numerical model. In this paper, we use the developed models to explore the performance enhancement potential of the structure in terms of (a) the control of global displacement - possibly the major performance criterion for the proposed structure owing to a narrow space available in the targeted site, and (b) the increase in energy dissipation by the existing U-bolt-type Friction-brake Devices - which are identified to have performed weakly when integrated into the structure. A set of parametric investigations have revealed correlations to achieve the first objective in terms of the structure's mass, particularly by manipulating the wire-net's characteristics, and has additionally disclosed the effects of the impacting-block's parameters. Towards achieving the second objective, another set of parametric investigations have led to a proposal of a few innovative improvements in the constitutive behaviour (model) of the studied brake device (dissipator), in addition to an important recommendation of careful handling of the device based on the identified potential flaw.

Analysis and synthesis of bianisotropic metasurfaces by using analytical approach based on equivalent parameters

NASA Astrophysics Data System (ADS)

Danaeifar, Mohammad; Granpayeh, Nosrat

2018-03-01

An analytical method is presented to analyze and synthesize bianisotropic metasurfaces. The equivalent parameters of metasurfaces in terms of meta-atom properties and other specifications of metasurfaces are derived. These parameters are related to electric, magnetic, and electromagnetic/magnetoelectric dipole moments of the bianisotropic media, and they can simplify the analysis of complicated and multilayer structures. A metasurface of split ring resonators is studied as an example demonstrating the proposed method. The optical properties of the meta-atom are explored, and the calculated polarizabilities are applied to find the reflection coefficient and the equivalent parameters of the metasurface. Finally, a structure consisting of two metasurfaces of the split ring resonators is provided, and the proposed analytical method is applied to derive the reflection coefficient. The validity of this analytical approach is verified by full-wave simulations which demonstrate good accuracy of the equivalent parameter method. This method can be used in the analysis and synthesis of bianisotropic metasurfaces with different materials and in different frequency ranges by considering electric, magnetic, and electromagnetic/magnetoelectric dipole moments.

A hydrological emulator for global applications - HE v1.0.0

NASA Astrophysics Data System (ADS)

Liu, Yaling; Hejazi, Mohamad; Li, Hongyi; Zhang, Xuesong; Leng, Guoyong

2018-03-01

While global hydrological models (GHMs) are very useful in exploring water resources and interactions between the Earth and human systems, their use often requires numerous model inputs, complex model calibration, and high computation costs. To overcome these challenges, we construct an efficient open-source and ready-to-use hydrological emulator (HE) that can mimic complex GHMs at a range of spatial scales (e.g., basin, region, globe). More specifically, we construct both a lumped and a distributed scheme of the HE based on the monthly abcd model to explore the tradeoff between computational cost and model fidelity. Model predictability and computational efficiency are evaluated in simulating global runoff from 1971 to 2010 with both the lumped and distributed schemes. The results are compared against the runoff product from the widely used Variable Infiltration Capacity (VIC) model. Our evaluation indicates that the lumped and distributed schemes present comparable results regarding annual total quantity, spatial pattern, and temporal variation of the major water fluxes (e.g., total runoff, evapotranspiration) across the global 235 basins (e.g., correlation coefficient r between the annual total runoff from either of these two schemes and the VIC is > 0.96), except for several cold (e.g., Arctic, interior Tibet), dry (e.g., North Africa) and mountainous (e.g., Argentina) regions. Compared against the monthly total runoff product from the VIC (aggregated from daily runoff), the global mean Kling-Gupta efficiencies are 0.75 and 0.79 for the lumped and distributed schemes, respectively, with the distributed scheme better capturing spatial heterogeneity. Notably, the computation efficiency of the lumped scheme is 2 orders of magnitude higher than the distributed one and 7 orders more efficient than the VIC model. A case study of uncertainty analysis for the world's 16 basins with top annual streamflow is conducted using 100 000 model simulations, and it demonstrates the lumped scheme's extraordinary advantage in computational efficiency. Our results suggest that the revised lumped abcd model can serve as an efficient and reasonable HE for complex GHMs and is suitable for broad practical use, and the distributed scheme is also an efficient alternative if spatial heterogeneity is of more interest.

5 CFR 550.1203 - Eligibility.

Code of Federal Regulations, 2011 CFR

2011-01-01

... on active duty in the armed forces may elect to receive a lump-sum payment for accumulated and... Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL... Department of Defense (DOD) must make a lump-sum payment to an employee who has unused annual leave that was...

5 CFR 550.1203 - Eligibility.

Code of Federal Regulations, 2010 CFR

2010-01-01

... on active duty in the armed forces may elect to receive a lump-sum payment for accumulated and... Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL... Department of Defense (DOD) must make a lump-sum payment to an employee who has unused annual leave that was...

29 CFR 4050.8 - Automatic lump sum.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION PLAN TERMINATIONS MISSING PARTICIPANTS § 4050.8 Automatic lump sum. This section applies to a missing participant whose designated benefit was... PBGC pays the benefit. (2) Payee. Payment will be made— (i) To the missing participant, if located; (ii...

Application of Biologically-Based Lumping To Investigate the Toxicological Interactions of a Complex Gasoline Mixture

EPA Science Inventory

People are often exposed to complex mixtures of environmental chemicals such as gasoline, tobacco smoke, water contaminants, or food additives. However, investigators have often considered complex mixtures as one lumped entity. Valuable information can be obtained from these exp...

A theoretical interpretation of the antibody-antigen interactions between Salmonella and a thickness shear mode (TSM) quartz resonator

NASA Astrophysics Data System (ADS)

Bailey, Claude Albert

This dissertation outlines the developmental procedure for a real-time food-borne pathogen detector that uses a thickness shear mode (TSM) quartz resonator. A theory is discussed which provides some understanding of the measured signals obtained from the TSM resonator-based Salmonella detector. The theory explains surface viscosity and mass effects, but has yet to be fully implemented for anomalous bacterial interactions. An equivalent circuit model for an immunochemical coating and its effect on the TSM resonator frequency is presented. The latter part of this dissertation describes immunological experiments with precoated piezoelectric quartz crystals. A highly purified immunological system was used to optimize the immobilization procedure. The use of biosensors is becoming a viable alternative to conventional analysis and promises to experience dramatic growth, especially after their true potential is realized and more cost-effective assays are developed. Concern about the safety of our food and water supplies will undoubtedly stimulate further research, and miniaturized biosensors will be developed for use by safety inspectors, and concerned personnel. A Salmonella detector has been demonstrated consisting of a TSM resonator with antibodies immobilized in a Langmuir Blodgett (LB) film on the surface [3]. Scanning Electron Microscopy (SEM) images of bound Salmonella bacteria to both polished and unpolished TSM resonators were taken to correlate the mass of the bound organism to the Sauerbrey equation. Antigen-antibody interactions change the acoustic resonant properties that are reflected in the sensor frequency response. The Salmonella detector operates in a liquid environment (Salmonella suspended in a phosphate buffered saline solution). The viscous properties of this liquid overlayer could influence the TSM resonator's response. Various liquid media (buffer solutions, chicken exudate, and varying fat contents of milk) were studied as a function of temperature (0 to 50°C). Kinematic viscosity test were performed with buffer solutions and fat free milk with varying quantities of Salmonella bacteria. The response of the TSM quartz resonator is examined theoretically by modeling the sensor load as a viscoelastic film with a semi-infinite Newtonian liquid overlayer. This study analyzes the surface mechanical impedance of the TSM resonator using a Butterworth Van-Dyke equivalent circuit model [4, 5], modified to describe the surface load as lumped circuit elements [6, 7]. The sensor's impedance parameters are first modeled as a generic surface load, and then decomposed into individual impedance parameters that describe the films viscoelastic properties and liquid overlayer behavior [7]. This document describes investigations of TSM resonator surface acoustic interactions---mass, fluid viscosity, and viscoelasticity---that affect the sensor. (Abstract shortened by UMI.)

Modeling Single Ventricle Physiology: Review of Engineering Tools to Study First Stage Palliation of Hypoplastic Left Heart Syndrome

PubMed Central

Biglino, Giovanni; Giardini, Alessandro; Hsia, Tain-Yen; Figliola, Richard; Taylor, Andrew M.; Schievano, Silvia

2013-01-01

First stage palliation of hypoplastic left heart syndrome, i.e., the Norwood operation, results in a complex physiological arrangement, involving different shunting options (modified Blalock-Taussig, RV-PA conduit, central shunt from the ascending aorta) and enlargement of the hypoplastic ascending aorta. Engineering techniques, both computational and experimental, can aid in the understanding of the Norwood physiology and their correct implementation can potentially lead to refinement of the decision-making process, by means of patient-specific simulations. This paper presents some of the available tools that can corroborate clinical evidence by providing detailed insight into the fluid dynamics of the Norwood circulation as well as alternative surgical scenarios (i.e., virtual surgery). Patient-specific anatomies can be manufactured by means of rapid prototyping and such models can be inserted in experimental set-ups (mock circulatory loops) that can provide a valuable source of validation data as well as hydrodynamic information. Such models can be tuned to respond to differing the patient physiologies. Experimental set-ups can also be compatible with visualization techniques, like particle image velocimetry and cardiovascular magnetic resonance, further adding to the knowledge of the local fluid dynamics. Multi-scale computational models include detailed three-dimensional (3D) anatomical information coupled to a lumped parameter network representing the remainder of the circulation. These models output both overall hemodynamic parameters while also enabling to investigate the local fluid dynamics of the aortic arch or the shunt. As an alternative, pure lumped parameter models can also be employed to model Stage 1 palliation, taking advantage of a much lower computational cost, albeit missing the 3D anatomical component. Finally, analytical techniques, such as wave intensity analysis, can be employed to study the Norwood physiology, providing a mechanistic perspective on the ventriculo-arterial coupling for this specific surgical scenario. PMID:24400277

Analysis of groundwater discharge with a lumped-parameter model, using a case study from Tajikistan

NASA Astrophysics Data System (ADS)

Pozdniakov, S. P.; Shestakov, V. M.

A lumped-parameter model of groundwater balance is proposed that permits an estimate of discharge variability in comparison with the variability of recharge, by taking into account the influence of aquifer parameters. Recharge-discharge relationships are analysed with the model for cases of deterministic and stochastic recharge time-series variations. The model is applied to study the temporal variability of groundwater discharge in a river valley in the territory of Tajikistan, an independent republic in Central Asia. Résumé Un modèle global de bilan d'eau souterraine a été développé pour estimer la variabilité de l'écoulement par rapport à celle de la recharge, en prenant en compte l'influence des paramètres de l'aquifère. Les relations entre recharge et écoulement sont analysées à l'aide du modèle pour des variations des chroniques de recharge soit déterministes, soit stochastiques. Le modèle est appliquéà l'étude de la variabilité temporelle de l'écoulement souterrain vers une rivière, dans le Tadjikistan, une république indépendante d'Asie centrale. Resumen Se propone un modelo de parámetros concentrados para realizar el balance de aguas subterráneas, el cual permite estimar la variabilidad en la descarga con respecto a la variabilidad en la recarga, en función de los parámetros que caracterizan el acuífero. Las relaciones entre recarga y descarga se analizan con el modelo para distintos casos de series temporales de recarga, tanto deterministas como estocásticas. El modelo se aplica al estudio de la variabilidad temporal de la descarga en un valle aluvial de Tadyikistán, una república independiente del Asia Central.

Observations on Rotating Cavitation and Cavitation Surge from the Development of the Fastrac Engine Turbopump

NASA Technical Reports Server (NTRS)

Zoladz, Thomas F.

2000-01-01

Observations regarding rotating cavitation and cavitation surge experienced during the development of the Fastrac engine turbopump are discussed. Detailed observations acquired from the analysis of both water flow and liquid oxygen test data are offered in this paper. Scaling and general comparison of rotating cavitation between water flow and liquid oxygen testing are discussed. Complex data features linking the localized rotating cavitation mechanism of the inducer to system surge components are described in detail. Finally a description of a lumped-parameter hydraulic system model developed to better understand observed data is given.

Overview of Rotating Cavitation and Cavitation Surge in the Fastrac Engine LOX Turbopump

NASA Technical Reports Server (NTRS)

Zoladz, Thomas; Turner, Jim (Technical Monitor)

2001-01-01

Observations regarding rotating cavitation and cavitation surge experienced during the development of the Fastrac 60 Klbf engine turbopump are discussed. Detailed observations from the analysis of both water flow and liquid oxygen test data are offered. Scaling and general comparison of rotating cavitation between water flow and liquid oxygen testing are discussed. Complex data features linking the localized rotating cavitation mechanism of the inducer to system surge components are described in detail. Finally a description of a simple lumped-parameter hydraulic system model developed to better understand observed data is given.

Vertical axis wind turbine drive train transient dynamics

NASA Technical Reports Server (NTRS)

Clauss, D. B.; Carne, T. G.

1982-01-01

Start up of a vertical axis wind turbine causes transient torque oscillations in the drive train with peak torques which may be over two and one half times the rated torque of the turbine. A computer code, based on a lumped parameter model of the drive train, was developed and tested for the low cost 17 meter turbine; the results show excellent agreement with field data. The code was used to predict the effect of a slip clutch on transient torque oscillations. It was demonstrated that a slip clutch located between the motor and brake can reduce peak torques by thirty eight percent.

Design of microstrip components by computer

NASA Technical Reports Server (NTRS)

Cisco, T. C.

1972-01-01

A number of computer programs are presented for use in the synthesis of microwave components in microstrip geometries. The programs compute the electrical and dimensional parameters required to synthesize couplers, filters, circulators, transformers, power splitters, diode switches, multipliers, diode attenuators and phase shifters. Additional programs are included to analyze and optimize cascaded transmission lines and lumped element networks, to analyze and synthesize Chebyshev and Butterworth filter prototypes, and to compute mixer intermodulation products. The programs are written in FORTRAN and the emphasis of the study is placed on the use of these programs and not on the theoretical aspects of the structures.

Modelling of the internal dynamics and density in a tens of joules plasma focus device

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

Marquez, Ariel; Gonzalez, Jose; Tarifeno-Saldivia, Ariel

2012-01-15

Using MHD theory, coupled differential equations were generated using a lumped parameter model to describe the internal behaviour of the pinch compression phase in plasma focus discharges. In order to provide these equations with appropriate initial conditions, the modelling of previous phases was included by describing the plasma sheath as planar shockwaves. The equations were solved numerically, and the results were contrasted against experimental measurements performed on the device PF-50J. The model is able to predict satisfactorily the timing and the radial electron density profile at the maximum compression.

Modeling and experimental characterization of Blackglas(TM) polymer pyrolysis to ceramic and thermodynamic characterization of Blackglas(TM) ceramic

NASA Astrophysics Data System (ADS)

Wang, Feng

2000-10-01

The transformation of Blackglas(TM) polymer to ceramic is characterized by TGA-RGA/MS, Si29 and C13 NMR. Si29 NMR reveals a dependence between the postcure temperature and the microstructure of the resin. The postcure temperature that appears to give optimal mechanical and oxidative properties of Blackglas(TM) ceramic is around 150°C. The pyrolysis processing models, which are the Lumped Parameters Model (LPM), the Mechanistic Kinetic Model (MKM) and the Redistribution Reaction Model (RRM), are developed to provide an effective window of processing parameters rather than a costly, time-consuming trial and error approach. The Lumped Parameters Model (LPM) is developed to study the effects of various parameters such as temperature, curing conditions and heating rates on mass loss during the pyrolysis of resin and green composites. It can be used for the model-predictive control of the pyrolysis process; The Mechanistic Kinetic Model (MKM) is developed on the basis of known chemistry and architecture of the polysiloxane for the transformation of Blackglas(TM) polymer to ceramic and the evolution of gases. The effects of various heating protocols on the outgassing kinetics have been studied to develop an optimum protocol for a rapid pyrolysis process which gives a composite with desirable mechanical properties; The Redistribution Reaction Model (RRM) is proposed to describe how the microcompositions of silicon oxycarbide change with respect to temperature, and to the ratio O/Si in the polymer precursor. A Thermodynamic Additivity Model (TAM) is developed to estimate the heat capacity, standard heat of formation and entropy of Blackglas(TM) ceramic by means of the Neumann Kopp rule and the available thermodynamic data of the Si-C and Si-O systems. Thermal stability of this ceramic is investigated by constructing predominance diagrams, and it is shown that the internal degradation reactions, which account for a significant loss of strength, will proceed further in the Blackglas(TM) matrix than in the Nicalon fibers. This probably will induce failure in the matrix at lower temperatures than in the fibers. The predominance diagrams also explain the high temperature oxidation, reduction and volatilization experiments on silicon and silicon carbide in high vacuum.

Lumped transmission line avalanche pulser

DOEpatents

Booth, R.

1995-07-18

A lumped linear avalanche transistor pulse generator utilizes stacked transistors in parallel within a stage and couples a plurality of said stages, in series with increasing zener diode limited voltages per stage and decreasing balanced capacitance load per stage to yield a high voltage, high and constant current, very short pulse. 8 figs.

45 CFR 158.241 - Form of rebate.

Code of Federal Regulations, 2011 CFR

2011-10-01

... method that was used for payment, such as credit card or direct debit. ... in the form of a premium credit, lump-sum check, or, if an enrollee paid the premium using a credit card or direct debit, by lump-sum reimbursement to the account used to pay the premium. (2) Any rebate...

A Laboratory Simulation of Urban Runoff and the Potential for Hydrograph Prediction with Curve Numbers

USDA-ARS?s Scientific Manuscript database

Urban drainages are mosaics of pervious and impervious surfaces, and prediction of runoff hydrology with a lumped modeling approach using the NRCS curve number may be appropriate. However, the prognostic capability of such a lumped approach is complicated by routing and connectivity amongst infiltra...

Lumped transmission line avalanche pulser

DOEpatents

Booth, Rex

1995-01-01

A lumped linear avalanche transistor pulse generator utilizes stacked transistors in parallel within a stage and couples a plurality of said stages, in series with increasing zener diode limited voltages per stage and decreasing balanced capacitance load per stage to yield a high voltage, high and constant current, very short pulse.

Optimization of subcritical water extraction parameters of antioxidant polyphenols from sea buckthorn (Hippophaë rhamnoides L.) seed residue.

PubMed

Gong, Ying; Zhang, Xiaofei; He, Li; Yan, Qiuli; Yuan, Fang; Gao, Yanxiang

2015-03-01

Polyphenols was extracted with subcritical water from the sea buckthorn seed residue (after oil recovery), and the extraction parameters were optimized using response surface methodology (RSM). The independent processing variables were extraction temperature, extraction time and the ratio of water to solid. The optimal extraction parameters for the extracts with highest ABTS radical scavenging activity were 120 °C, 36 min and the water to solid ratio of 20, and the maximize antioxidant capacity value was 32.42 mmol Trolox equivalent (TE)/100 g. Under the optimal conditions, the yield of total phenolics, total flavonoids and proanthocyanidins was 36.62 mg gallic acid equivalents (GAE)/g, 19.98 mg rutin equivalent (RE)/g and 10.76 mg catechin equivalents (CE)/g, respectively.

Mechanistic equivalent circuit modelling of a commercial polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Giner-Sanz, J. J.; Ortega, E. M.; Pérez-Herranz, V.

2018-03-01

Electrochemical impedance spectroscopy (EIS) has been widely used in the fuel cell field since it allows deconvolving the different physic-chemical processes that affect the fuel cell performance. Typically, EIS spectra are modelled using electric equivalent circuits. In this work, EIS spectra of an individual cell of a commercial PEM fuel cell stack were obtained experimentally. The goal was to obtain a mechanistic electric equivalent circuit in order to model the experimental EIS spectra. A mechanistic electric equivalent circuit is a semiempirical modelling technique which is based on obtaining an equivalent circuit that does not only correctly fit the experimental spectra, but which elements have a mechanistic physical meaning. In order to obtain the aforementioned electric equivalent circuit, 12 different models with defined physical meanings were proposed. These equivalent circuits were fitted to the obtained EIS spectra. A 2 step selection process was performed. In the first step, a group of 4 circuits were preselected out of the initial list of 12, based on general fitting indicators as the determination coefficient and the fitted parameter uncertainty. In the second step, one of the 4 preselected circuits was selected on account of the consistency of the fitted parameter values with the physical meaning of each parameter.

Energy-state formulation of lumped volume dynamic equations with application to a simplified free piston Stirling engine

NASA Technical Reports Server (NTRS)

Daniele, C. J.; Lorenzo, C. F.

1979-01-01

Lumped volume dynamic equations are derived using an energy state formulation. This technique requires that kinetic and potential energy state functions be written for the physical system being investigated. To account for losses in the system, a Rayleigh dissipation function is formed. Using these functions, a Lagrangian is formed and using Lagrange's equation, the equations of motion for the system are derived. The results of the application of this technique to a lumped volume are used to derive a model for the free piston Stirling engine. The model was simplified and programmed on an analog computer. Results are given comparing the model response with experimental data.

Energy-state formulation of lumped volume dynamic equations with application to a simplified free piston Stirling engine

NASA Technical Reports Server (NTRS)

Daniele, C. J.; Lorenzo, C. F.

1979-01-01

Lumped volume dynamic equations are derived using an energy-state formulation. This technique requires that kinetic and potential energy state functions be written for the physical system being investigated. To account for losses in the system, a Rayleigh dissipation function is also formed. Using these functions, a Lagrangian is formed and using Lagrange's equation, the equations of motion for the system are derived. The results of the application of this technique to a lumped volume are used to derive a model for the free-piston Stirling engine. The model was simplified and programmed on an analog computer. Results are given comparing the model response with experimental data.

Sensitivity of Lumped Constraints Using the Adjoint Method

NASA Technical Reports Server (NTRS)

Akgun, Mehmet A.; Haftka, Raphael T.; Wu, K. Chauncey; Walsh, Joanne L.

1999-01-01

Adjoint sensitivity calculation of stress, buckling and displacement constraints may be much less expensive than direct sensitivity calculation when the number of load cases is large. Adjoint stress and displacement sensitivities are available in the literature. Expressions for local buckling sensitivity of isotropic plate elements are derived in this study. Computational efficiency of the adjoint method is sensitive to the number of constraints and, therefore, the method benefits from constraint lumping. A continuum version of the Kreisselmeier-Steinhauser (KS) function is chosen to lump constraints. The adjoint and direct methods are compared for three examples: a truss structure, a simple HSCT wing model, and a large HSCT model. These sensitivity derivatives are then used in optimization.

Adaptive sliding control of non-autonomous active suspension systems with time-varying loadings

NASA Astrophysics Data System (ADS)

Chen, Po-Chang; Huang, An-Chyau

2005-04-01

An adaptive sliding controller is proposed in this paper for controlling a non-autonomous quarter-car suspension system with time-varying loadings. The bound of the car-body loading is assumed to be available. Then, the reference coordinate is placed at the static position under the nominal loading so that the system dynamic equation is derived. Due to spring nonlinearities, the system property becomes asymmetric after coordinate transformation. Besides, in practical cases, system parameters are not easy to be obtained precisely for controller design. Therefore, in this paper, system uncertainties are lumped into two unknown time-varying functions. Since the variation bound of one of the unknown functions is not available, conventional adaptive schemes and robust designs are not applicable. To deal with this problem, the function approximation technique is employed to represent the unknown function as a finite combination of basis functions. The Lyapunov direct method can thus be used to find adaptive laws for updating coefficients in the approximating series and to prove stability of the closed-loop system. Since the position and velocity measurements of the unsprung mass are lumped into the unknown function, there is no need to install sensors on the axle and wheel assembly in the actual implementation. Simulation results are presented to show the performance of the proposed strategy.

24 CFR 84.82 - Provisions applicable only to lump sum grants.

Code of Federal Regulations, 2014 CFR

2014-04-01

... INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Use of Lump Sum Grants § 84.82... to performance and unit cost data. (4) Where HUD guarantees or insures the repayment of money... acceptable sureties, as prescribed in 31 CFR part 223, “Surety Companies Doing Business with the United...

24 CFR 84.82 - Provisions applicable only to lump sum grants.

Code of Federal Regulations, 2013 CFR

2013-04-01

... INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Use of Lump Sum Grants § 84.82... to performance and unit cost data. (4) Where HUD guarantees or insures the repayment of money... acceptable sureties, as prescribed in 31 CFR part 223, “Surety Companies Doing Business with the United...

24 CFR 84.82 - Provisions applicable only to lump sum grants.

Code of Federal Regulations, 2012 CFR

2012-04-01

... INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Use of Lump Sum Grants § 84.82... to performance and unit cost data. (4) Where HUD guarantees or insures the repayment of money... acceptable sureties, as prescribed in 31 CFR part 223, “Surety Companies Doing Business with the United...

24 CFR 570.513 - Lump sum drawdown for financing of property rehabilitation activities.

Code of Federal Regulations, 2010 CFR

2010-04-01

... recipient shall execute a written agreement with one or more private financial institutions for the..., the anticipated level of rehabilitation activities by the financial institution, the rate of interest and other benefits to be provided by the financial institution in return for the lump sum deposit, and...

5 CFR 831.2005 - Designation of beneficiary for lump-sum payment.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Designation of beneficiary for lump-sum payment. 831.2005 Section 831.2005 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED.... (e) A change of beneficiary may be made at any time and without the knowledge or consent of the...

5 CFR 831.2005 - Designation of beneficiary for lump-sum payment.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Designation of beneficiary for lump-sum payment. 831.2005 Section 831.2005 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED.... (e) A change of beneficiary may be made at any time and without the knowledge or consent of the...

5 CFR 831.2005 - Designation of beneficiary for lump-sum payment.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Designation of beneficiary for lump-sum payment. 831.2005 Section 831.2005 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED.... (e) A change of beneficiary may be made at any time and without the knowledge or consent of the...

5 CFR 831.2005 - Designation of beneficiary for lump-sum payment.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Designation of beneficiary for lump-sum payment. 831.2005 Section 831.2005 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED.... (e) A change of beneficiary may be made at any time and without the knowledge or consent of the...

20 CFR 217.10 - Application filed after death.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Application filed after death. 217.10 Section... APPLICATION FOR ANNUITY OR LUMP SUM Applications § 217.10 Application filed after death. (a) A survivor... expenses dies before applying for the lump-sum death payment under part 234 of this chapter. The...

5 CFR 550.1205 - Calculating a lump-sum payment.

Code of Federal Regulations, 2010 CFR

2010-01-01

... rate employee for all regularly scheduled periods of night shift duty covered by the unused annual... day and night shifts, the night differential is payable for that portion of the lump-sum period that would have occurred when the employee was scheduled to work night shifts. (ii) Premium pay under 5 U.S.C...

26 CFR 1.411(a)(13)-1 - Statutory hybrid plans.

Code of Federal Regulations, 2014 CFR

2014-04-01

... another benefit amount) and at least one of those formulas is a statutory hybrid benefit formula, the... certain statutory hybrid plans that determine benefits under a lump sum-based benefit formula. Paragraph... current balance or current value under a lump sum-based benefit formula. Pursuant to section 411(a)(13)(A...

26 CFR 1.411(a)(13)-1 - Statutory hybrid plans.

Code of Federal Regulations, 2013 CFR

2013-04-01

... another benefit amount) and at least one of those formulas is a statutory hybrid benefit formula, the... certain statutory hybrid plans that determine benefits under a lump sum-based benefit formula. Paragraph... current balance or current value under a lump sum-based benefit formula. Pursuant to section 411(a)(13)(A...

26 CFR 1.411(a)(13)-1 - Statutory hybrid plans.

Code of Federal Regulations, 2012 CFR

2012-04-01

... another benefit amount) and at least one of those formulas is a statutory hybrid benefit formula, the... certain statutory hybrid plans that determine benefits under a lump sum-based benefit formula. Paragraph... current balance or current value under a lump sum-based benefit formula. Pursuant to section 411(a)(13)(A...

26 CFR 1.411(a)(13)-1 - Statutory hybrid plans.

Code of Federal Regulations, 2011 CFR

2011-04-01

... another benefit amount) and at least one of those formulas is a statutory hybrid benefit formula, the... certain statutory hybrid plans that determine benefits under a lump sum-based benefit formula. Paragraph... current balance or current value under a lump sum-based benefit formula. Pursuant to section 411(a)(13)(A...

20 CFR 10.422 - May compensation payments be issued in a lump sum?

Code of Federal Regulations, 2010 CFR

2010-04-01

...-sum payments for wage-loss benefits, OWCP will not exercise further discretion in the matter. This... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false May compensation payments be issued in a lump sum? 10.422 Section 10.422 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF...

5 CFR 831.2005 - Designation of beneficiary for lump-sum payment.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Designation of beneficiary for lump-sum payment. 831.2005 Section 831.2005 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED.... (e) A change of beneficiary may be made at any time and without the knowledge or consent of the...

29 CFR 1450.12 - Collection in installments.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the debtor is financially unable to pay the indebtedness in one lump sum, payment may be accepted in... unable to pay the debt in one lump sum. If FMCS agrees to accept payment in regular installments it will... the debtor's ability to pay. If possible, the installment payments should be sufficient in size and...

29 CFR 1450.12 - Collection in installments.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the debtor is financially unable to pay the indebtedness in one lump sum, payment may be accepted in... unable to pay the debt in one lump sum. If FMCS agrees to accept payment in regular installments it will... the debtor's ability to pay. If possible, the installment payments should be sufficient in size and...

29 CFR 1450.12 - Collection in installments.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the debtor is financially unable to pay the indebtedness in one lump sum, payment may be accepted in... unable to pay the debt in one lump sum. If FMCS agrees to accept payment in regular installments it will... the debtor's ability to pay. If possible, the installment payments should be sufficient in size and...

29 CFR 1450.12 - Collection in installments.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the debtor is financially unable to pay the indebtedness in one lump sum, payment may be accepted in... unable to pay the debt in one lump sum. If FMCS agrees to accept payment in regular installments it will... the debtor's ability to pay. If possible, the installment payments should be sufficient in size and...

20 CFR 217.10 - Application filed after death.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Application filed after death. 217.10 Section... APPLICATION FOR ANNUITY OR LUMP SUM Applications § 217.10 Application filed after death. (a) A survivor... expenses dies before applying for the lump-sum death payment under part 234 of this chapter. The...

20 CFR 217.10 - Application filed after death.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Application filed after death. 217.10 Section... APPLICATION FOR ANNUITY OR LUMP SUM Applications § 217.10 Application filed after death. (a) A survivor... expenses dies before applying for the lump-sum death payment under part 234 of this chapter. The...

20 CFR 217.10 - Application filed after death.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Application filed after death. 217.10 Section... APPLICATION FOR ANNUITY OR LUMP SUM Applications § 217.10 Application filed after death. (a) A survivor... expenses dies before applying for the lump-sum death payment under part 234 of this chapter. The...

20 CFR 217.10 - Application filed after death.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Application filed after death. 217.10 Section... APPLICATION FOR ANNUITY OR LUMP SUM Applications § 217.10 Application filed after death. (a) A survivor... expenses dies before applying for the lump-sum death payment under part 234 of this chapter. The...

A lumped-circuit model for the radiation impedance of a circular piston in a rigid baffle.

PubMed

Bozkurt, Ayhan

2008-09-01

The radiation impedance of a piston transducer mounted in a rigid baffle has been widely addressed in the literature. The real and imaginary parts of the impedance are described by the first order Bessel and Struve functions, respectively. Although there are power series expansions for both functions, the analytic formulation of a lumped circuit is not trivial. In this paper, we present an empirical approach to the derivation of a lumped-circuit model for the radiation impedance expression, based on observations on the near-field behavior of stored kinetic and elastic energy. The field analysis is carried out using a finite element method model of the piston and surrounding fluid medium. We show that fluctuations in the real and imaginary components of the impedance can be modeled by series and shunt tank circuits, each of which shape a certain section of the impedance curve. Because the model is composed of lumped-circuit elements, it can be used in circuit simulators. Consequently, the proposed model is useful for the analysis of transducer front-end circuits.

Health monitoring system for transmission shafts based on adaptive parameter identification

NASA Astrophysics Data System (ADS)

Souflas, I.; Pezouvanis, A.; Ebrahimi, K. M.

2018-05-01

A health monitoring system for a transmission shaft is proposed. The solution is based on the real-time identification of the physical characteristics of the transmission shaft i.e. stiffness and damping coefficients, by using a physical oriented model and linear recursive identification. The efficacy of the suggested condition monitoring system is demonstrated on a prototype transient engine testing facility equipped with a transmission shaft capable of varying its physical properties. Simulation studies reveal that coupling shaft faults can be detected and isolated using the proposed condition monitoring system. Besides, the performance of various recursive identification algorithms is addressed. The results of this work recommend that the health status of engine dynamometer shafts can be monitored using a simple lumped-parameter shaft model and a linear recursive identification algorithm which makes the concept practically viable.

LACIE performance predictor final operational capability program description, volume 1

NASA Technical Reports Server (NTRS)

1976-01-01

The program EPHEMS computes the orbital parameters for up to two vehicles orbiting the earth for up to 549 days. The data represents a continuous swath about the earth, producing tables which can be used to determine when and if certain land segments will be covered. The program GRID processes NASA's climatology tape to obtain the weather indices along with associated latitudes and longitudes. The program LUMP takes substrata historical data and sample segment ID, crop window, crop window error and statistical data, checks for valid input parameters and generates the segment ID file, crop window file and the substrata historical file. Finally, the System Error Executive (SEE) Program checks YES error and truth data, CAMS error data, and signature extension data for validity and missing elements. A message is printed for each error found.

Ground-based testing of the dynamics of flexible space structures using band mechanisms

NASA Technical Reports Server (NTRS)

Yang, L. F.; Chew, Meng-Sang

1991-01-01

A suspension system based on a band mechanism is studied to provide the free-free conditions for ground based validation testing of flexible space structures. The band mechanism consists of a noncircular disk with a convex profile, preloaded by torsional springs at its center of rotation so that static equilibrium of the test structure is maintained at any vertical location; the gravitational force will be directly counteracted during dynamic testing of the space structure. This noncircular disk within the suspension system can be configured to remain unchanged for test articles with the different weights as long as the torsional spring is replaced to maintain the originally designed frequency ratio of W/k sub s. Simulations of test articles which are modeled as lumped parameter as well as continuous parameter systems, are also presented.

Computational analysis of hybrid Norwood circulation with distal aortic arch obstruction and reverse Blalock-Taussig shunt.

PubMed

Ceballos, Andres; Argueta-Morales, I Ricardo; Divo, Eduardo; Osorio, Ruben; Caldarone, Christopher A; Kassab, Alain J; Decampli, William M

2012-11-01

The hemodynamics characteristics of the hybrid Norwood (HN) procedure differ from those of the conventional Norwood and are not fully understood. We present a multiscale model of HN circulation to understand local hemodynamics and effects of aortic arch stenosis and a reverse Blalock-Taussig shunt (RBTS) on coronary and carotid perfusion. Four 3-dimensional models of four HN anatomic variants were developed, with and without 90% distal preductal arch stenosis and with and without a 4-mm RBTS. A lumped parameter model of the circulation was coupled to a local 3-dimensional computational fluid dynamics model. Outputs from the lumped parameter model provided waveform boundary conditions for the computational fluid dynamics model. A 90% distal arch stenosis reduced pressure and net flow-rate through the coronary and carotid arteries by 30%. Addition of the RBTS completely restored pressure and flow rate to baseline in these vessels. Zones of flow stagnation, flow reversal, and recirculation in the presence of stenosis were rendered more orderly by addition of the RBTS. In the absence of stenosis, presence of the shunt resulted in extensive zones of disturbed flow within the RBTS and arch. We found that a 4-mm × 21-mm RBTS completely compensated for the effects of a 90% discrete stenosis of the distal aortic arch in the HN. Placed preventatively, the RBTS and arch displayed zones with thrombogenic potential showing recirculation and stagnation that persist for a substantial fraction of the cardiac cycle, indicating that anticoagulation should be considered with a prophylactic RBTS. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Regional Evaluation of Groundwater Age Distributions Using Lumped Parameter Models with Large, Sparse Datasets: Example from the Central Valley, California, USA

NASA Astrophysics Data System (ADS)

Jurgens, B. C.; Bohlke, J. K.; Voss, S.; Fram, M. S.; Esser, B.

2015-12-01

Tracer-based, lumped parameter models (LPMs) are an appealing way to estimate the distribution of age for groundwater because the cost of sampling wells is often less than building numerical groundwater flow models sufficiently complex to provide groundwater age distributions. In practice, however, tracer datasets are often incomplete because of anthropogenic or terrigenic contamination of tracers, or analytical limitations. While age interpretations using such datsets can have large uncertainties, it may still be possible to identify key parts of the age distribution if LPMs are carefully chosen to match hydrogeologic conceptualization and the degree of age mixing is reasonably estimated. We developed a systematic approach for evaluating groundwater age distributions using LPMs with a large but incomplete set of tracer data (3H, 3Hetrit, 14C, and CFCs) from 535 wells, mostly used for public supply, in the Central Valley, California, USA that were sampled by the USGS for the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment or the USGS National Water Quality Assessment Programs. In addition to mean ages, LPMs gave estimates of unsaturated zone travel times, recharge rates for pre- and post-development groundwater, the degree of age mixing in wells, proportion of young water (<60 yrs), and the depth of the boundary between post-development and predevelopment groundwater throughout the Central Valley. Age interpretations were evaluated by comparing past nitrate trends with LPM predicted trends, and whether the presence or absence of anthropogenic organic compounds was consistent with model results. This study illustrates a practical approach for assessing groundwater age information at a large scale to reveal important characteristics about the age structure of a major aquifer, and of the water supplies being derived from it.

Assessing aquifer vulnerability from lumped parameter modeling of modern water proportions in groundwater mixtures - Application to nitrate pollution in California's South Coast Range

NASA Astrophysics Data System (ADS)

Hagedorn, B.; Ruane, M.; Clark, N.

2017-12-01

In California, the overuse of synthetic fertilizers and manure in agriculture have caused nitrate (NO3) to be one of the state's most widespread groundwater pollutants. Given that nitrogen fertilizer applications have steadily increased since the 1950s and given that soil percolation and recharge transit times in California can exceed timescales of decades, the nitrate impact on groundwater resources is likely a legacy for years and even decades to come. This study presents a methodology for groundwater vulnerability assessment that operates independently of difficult-to-constrain soil and aquifer property data (i.e., saturated thickness, texture, porosity, conductivity, etc.), but rather utilizes groundwater age and, more importantly, groundwater mixing information to illustrate actual vulnerability at the water table. To accomplish this, the modern (i.e., less than 60-year old) water proportion (MWP) in groundwater mixtures is computed via lumped parameter modeling of chemical tracer (i.e., 3H, 14C and 3Hetrit) data. These MWPs are then linked to groundwater dissolved oxygen (DO) values to describe the risk for soil zone-derived nitrate to accumulate in the saturated zone. Preliminary studies carried out for 71 wells in California's South Coast Range-Coastal (SCRC) study unit reveal MWP values derived from binary dispersion models of 3.24% to 21.8%. The fact that high MWPs generally coincide with oxic (DO ≥1.5 mg/L) groundwater conditions underscores the risk towards increased groundwater NO3 pollution for many of the tested wells. These results support the conclusion that best agricultural management and policy objectives should incorporate groundwater vulnerability models that are developed at the same spatial scale as the decision making.

Loudspeakers: Modeling and control

NASA Astrophysics Data System (ADS)

Al-Ali, Khalid Mohammad

This thesis documented a comprehensive study of loudspeaker modeling and control. A lumped-parameter model for a voice-coil loudspeaker in a vented enclosure was presented that derived from a consideration of physical principles. In addition, a low-frequency (20 Hz to 100 Hz), feedback control method designed to improve the nonlinear performance of the loudspeaker and a suitable performance measure for use in design and evaluation were proposed. Data from experiments performed on a variety of actual loudspeakers confirmed the practicality of the theory developed in this work. The lumped-parameter loudspeaker model, although simple, captured much of the nonlinear behavior of the loudspeaker. In addition, the model formulation allowed a straightforward application of modern control system methods and lent itself well to modern parametric identification techniques. The nonlinear performance of the loudspeaker system was evaluated using a suitable distortion measure that was proposed and compared with other distortion measures currently used in practice. Furthermore, the linearizing effect of feedback using a linear controller (both static and dynamic) was studied on a class of nonlinear systems. The results illustrated that the distortion reduction was potentially significant and a useful upper bound on the closed-loop distortion was found based on the sensitivity function of the system's linearization. A feedback scheme based on robust control theory was chosen for application to the loudspeaker system. Using the pressure output of the loudspeaker system for feedback, the technique offered significant advantages over those previously attempted. Illustrative examples were presented that proved the applicability of the theory developed in this dissertation to a variety of loudspeaker systems. The examples included a vented loudspeaker model and actual loudspeakers enclosed in both vented and sealed configurations. In each example, predictable and measurable distortion reduction at the output of the closed-loop system was recorded.

Groundwater discharge in high-mountain watersheds: A valuable resource for downstream semi-arid zones. The case of the Bérchules River in Sierra Nevada (Southern Spain).

PubMed

Jódar, Jorge; Cabrera, José Antonio; Martos-Rosillo, Sergio; Ruiz-Constán, Ana; González-Ramón, Antonio; Lambán, Luis Javier; Herrera, Christian; Custodio, Emilio

2017-09-01

Aquifers in permeable formations developed in high-mountain watersheds slow down the transfer of snowmelt to rivers, modifying rivers' flow pattern. To gain insight into the processes that control the hydrologic response of such systems the role played by groundwater in an alpine basin located at the southeastern part of the Iberian Peninsula is investigated. As data in these environments is generally scarce and its variability is high, simple lumped parameter hydrological models that consider the groundwater component and snow accumulation and melting are needed. Instead of using existing models that use many parameters, the Témez lumped hydrological model of common use in Spain and Ibero-American countries is selected and modified to consider snow to get a simplified tool to separate hydrograph components. The result is the TDD model (Témez-Degree Day) which is applied in a high mountain watershed with seasonal snow cover in Southern Spain to help in quantifying groundwater recharge and determining the groundwater contribution to the outflow. Average groundwater recharge is about 23% of the precipitation, and groundwater contribution to total outflow ranges between 70 and 97%. Direct surface runoff is 1% of precipitation. These values depend on the existence of snow. Results are consistent with those obtained with chloride atmospheric deposition mass balances by other authors. They highlight the important role of groundwater in high mountain areas, which is enhanced by seasonal snow cover. Results compare well with other areas. This effect is often neglected in water planning, but can be easily taken into account just by extending the water balance tool in use, or any other, following the procedure that has being developed. Copyright © 2017 Elsevier B.V. All rights reserved.

Analyses of Longitudinal Mode Combustion Instability in J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Protz, C. S.; Casiano, M. J.; Kenny, R. J.

2011-01-01

The National Aeronautics and Space Administration (NASA) and Pratt & Whitney Rocketdyne are developing a liquid oxygen/liquid hydrogen rocket engine for future upper stage and trans-lunar applications. This engine, designated the J-2X, is a higher pressure, higher thrust variant of the Apollo-era J-2 engine. The contract for development was let to Pratt & Whitney Rocketdyne in 2006. Over the past several years, development of the gas generator for the J-2X engine has progressed through a variety of workhorse injector, chamber, and feed system configurations on the component test stand at the NASA Marshall Space Flight Center (MSFC). Several of the initial configurations resulted in combustion instability of the workhorse gas generator assembly at a frequency near the first longitudinal mode of the combustion chamber. In this paper, several aspects of these combustion instabilities are discussed, including injector, combustion chamber, feed system, and nozzle influences. To ensure elimination of the instabilities at the engine level, and to understand the stability margin, the gas generator system has been modeled at the NASA MSFC with two techniques, the Rocket Combustor Interaction Design and Analysis (ROCCID) code and a lumped-parameter MATLAB(TradeMark) model created as an alternative calculation to the ROCCID methodology. To correctly predict the instability characteristics of all the chamber and injector geometries and test conditions as a whole, several inputs to the submodels in ROCCID and the MATLAB(TradeMark) model were modified. Extensive sensitivity calculations were conducted to determine how to model and anchor a lumped-parameter injector response, and finite-element and acoustic analyses were conducted on several complicated combustion chamber geometries to determine how to model and anchor the chamber response. These modifications and their ramification for future stability analyses of this type are discussed.

Combustion Stability Analyses for J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Protz, C. S.; Casiano, M. J.; Kenny, R. J.

2010-01-01

The National Aeronautics and Space Administration (NASA) is developing a liquid oxygen/liquid hydrogen rocket engine for upper stage and trans-lunar applications of the Ares vehicles for the Constellation program. This engine, designated the J-2X, is a higher pressure, higher thrust variant of the Apollo-era J-2 engine. Development was contracted to Pratt & Whitney Rocketdyne in 2006. Over the past several years, development of the gas generator for the J-2X engine has progressed through a variety of workhorse injector, chamber, and feed system configurations. Several of these configurations have resulted in injection-coupled combustion instability of the gas generator assembly at the first longitudinal mode of the combustion chamber. In this paper, the longitudinal mode combustion instabilities observed on the workhorse test stand are discussed in detail. Aspects of this combustion instability have been modeled at the NASA Marshall Space Flight Center with several codes, including the Rocket Combustor Interaction Design and Analysis (ROCCID) code and a new lumped-parameter MatLab model. To accurately predict the instability characteristics of all the chamber and injector geometries and test conditions, several features of the submodels in the ROCCID suite of calculations required modification. Finite-element analyses were conducted of several complicated combustion chamber geometries to determine how to model and anchor the chamber response in ROCCID. A large suite of sensitivity calculations were conducted to determine how to model and anchor the injector response in ROCCID. These modifications and their ramification for future stability analyses of this type are discussed in detail. The lumped-parameter MatLab model of the gas generator assembly was created as an alternative calculation to the ROCCID methodology. This paper also describes this model and the stability calculations.

Assessment of health risks due to arsenic from iron ore lumps in a beach setting.

PubMed

Swartjes, Frank A; Janssen, Paul J C M

2016-09-01

In 2011, an artificial hook-shaped peninsula of 128ha beach area was created along the Dutch coast, containing thousands of iron ore lumps, which include arsenic from natural origin. Elemental arsenic and inorganic arsenic induce a range of toxicological effects and has been classified as proven human carcinogens. The combination of easy access to the beach and the presence of arsenic raised concern about possible human health effects by the local authorities. The objective of this study is therefore to investigate human health risks from the presence of arsenic-containing iron ore lumps in a beach setting. The exposure scenarios underlying the human health-based risk limits for contaminated land in The Netherlands, based on soil material ingestion and a residential setting, are not appropriate. Two specific exposure scenarios related to the playing with iron ore lumps on the beach ('sandcastle building') are developed on the basis of expert judgement, relating to children in the age of 2 to 12years, i.e., a worst case exposure scenario and a precautionary scenario. Subsequently, exposure is calculated by the quantification of the following factors: hand loading, soil-mouth transfer effectivity, hand-mouth contact frequency, contact surface, body weight and the relative oral bioavailability factor. By lack of consensus on a universal reference dose for arsenic for use in the stage of risk characterization, three different types of assessments have been evaluated: on the basis of the current Provisional Tolerable Daily Intake (PTWI), on the basis of the Benchmark Dose Lower limit (BMDL), and by a comparison of exposure from the iron ore lumps with background exposure. It is concluded, certainly from the perspective of the conservative exposure assessment, that unacceptable human health risks due to exposure to arsenic from the iron ore lumps are unlikely and there is no need for risk management actions. Copyright © 2016 Elsevier B.V. All rights reserved.

A hydrological emulator for global applications – HE v1.0.0

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

Liu, Yaling; Hejazi, Mohamad; Li, Hongyi

While global hydrological models (GHMs) are very useful in exploring water resources and interactions between the Earth and human systems, their use often requires numerous model inputs, complex model calibration, and high computation costs. To overcome these challenges, we construct an efficient open-source and ready-to-use hydrological emulator (HE) that can mimic complex GHMs at a range of spatial scales (e.g., basin, region, globe). More specifically, we construct both a lumped and a distributed scheme of the HE based on the monthly abcd model to explore the tradeoff between computational cost and model fidelity. Model predictability and computational efficiency are evaluatedmore » in simulating global runoff from 1971 to 2010 with both the lumped and distributed schemes. The results are compared against the runoff product from the widely used Variable Infiltration Capacity (VIC) model. Our evaluation indicates that the lumped and distributed schemes present comparable results regarding annual total quantity, spatial pattern, and temporal variation of the major water fluxes (e.g., total runoff, evapotranspiration) across the global 235 basins (e.g., correlation coefficient r between the annual total runoff from either of these two schemes and the VIC is > 0.96), except for several cold (e.g., Arctic, interior Tibet), dry (e.g., North Africa) and mountainous (e.g., Argentina) regions. Compared against the monthly total runoff product from the VIC (aggregated from daily runoff), the global mean Kling–Gupta efficiencies are 0.75 and 0.79 for the lumped and distributed schemes, respectively, with the distributed scheme better capturing spatial heterogeneity. Notably, the computation efficiency of the lumped scheme is 2 orders of magnitude higher than the distributed one and 7 orders more efficient than the VIC model. A case study of uncertainty analysis for the world's 16 basins with top annual streamflow is conducted using 100 000 model simulations, and it demonstrates the lumped scheme's extraordinary advantage in computational efficiency. Lastly, our results suggest that the revised lumped abcd model can serve as an efficient and reasonable HE for complex GHMs and is suitable for broad practical use, and the distributed scheme is also an efficient alternative if spatial heterogeneity is of more interest.« less

Calibration of the ARID robot

NASA Technical Reports Server (NTRS)

Doty, Keith L

1992-01-01

The author has formulated a new, general model for specifying the kinematic properties of serial manipulators. The new model kinematic parameters do not suffer discontinuities when nominally parallel adjacent axes deviate from exact parallelism. From this new theory the author develops a first-order, lumped-parameter, calibration-model for the ARID manipulator. Next, the author develops a calibration methodology for the ARID based on visual and acoustic sensing. A sensor platform, consisting of a camera and four sonars attached to the ARID end frame, performs calibration measurements. A calibration measurement consists of processing one visual frame of an accurately placed calibration image and recording four acoustic range measurements. A minimum of two measurement protocols determine the kinematics calibration-model of the ARID for a particular region: assuming the joint displacements are accurately measured, the calibration surface is planar, and the kinematic parameters do not vary rapidly in the region. No theoretical or practical limitations appear to contra-indicate the feasibility of the calibration method developed here.

Design and implementation of an air-conditioning system with storage tank for load shifting

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

Hsu, Y.Y.; Wu, C.J.; Liou, K.L.

1987-11-01

The experience with the design, simulation and implementation of an air-conditioning system with chilled water storage tank is presented in this paper. The system is used to shift air-conditioning load of residential and commercial buildings from on-peak to off-peak period. Demand-side load management can thus be achieved if many buildings are equipped with such storage devices. In the design of this system, a lumped-parameter circuit model is first employed to simulate the heat transfer within the air-conditioned building such that the required capacity of the storage tank can be figured out. Then, a set of desirable parameters for the temperaturemore » controller of the system are determined using the parameter plane method and the root locus method. The validity of the proposed mathematical model and design approach is verified by comparing the results obtained from field tests with those from the computer simulations. Cost-benefit analysis of the system is also discussed.« less

Impedance analysis of cultured cells: a mean-field electrical response model for electric cell-substrate impedance sensing technique.

PubMed

Urdapilleta, E; Bellotti, M; Bonetto, F J

2006-10-01

In this paper we present a model to describe the electrical properties of a confluent cell monolayer cultured on gold microelectrodes to be used with electric cell-substrate impedance sensing technique. This model was developed from microscopic considerations (distributed effects), and by assuming that the monolayer is an element with mean electrical characteristics (specific lumped parameters). No assumptions were made about cell morphology. The model has only three adjustable parameters. This model and other models currently used for data analysis are compared with data we obtained from electrical measurements of confluent monolayers of Madin-Darby Canine Kidney cells. One important parameter is the cell-substrate height and we found that estimates of this magnitude strongly differ depending on the model used for the analysis. We analyze the origin of the discrepancies, concluding that the estimates from the different models can be considered as limits for the true value of the cell-substrate height.

The Equivalence of Two Methods of Parameter Estimation for the Rasch Model.

ERIC Educational Resources Information Center

Blackwood, Larry G.; Bradley, Edwin L.

1989-01-01

Two methods of estimating parameters in the Rasch model are compared. The equivalence of likelihood estimations from the model of G. J. Mellenbergh and P. Vijn (1981) and from usual unconditional maximum likelihood (UML) estimation is demonstrated. Mellenbergh and Vijn's model is a convenient method of calculating UML estimates. (SLD)

Numerical Homogenization of Jointed Rock Masses Using Wave Propagation Simulation

NASA Astrophysics Data System (ADS)

Gasmi, Hatem; Hamdi, Essaïeb; Bouden Romdhane, Nejla

2014-07-01

Homogenization in fractured rock analyses is essentially based on the calculation of equivalent elastic parameters. In this paper, a new numerical homogenization method that was programmed by means of a MATLAB code, called HLA-Dissim, is presented. The developed approach simulates a discontinuity network of real rock masses based on the International Society of Rock Mechanics (ISRM) scanline field mapping methodology. Then, it evaluates a series of classic joint parameters to characterize density (RQD, specific length of discontinuities). A pulse wave, characterized by its amplitude, central frequency, and duration, is propagated from a source point to a receiver point of the simulated jointed rock mass using a complex recursive method for evaluating the transmission and reflection coefficient for each simulated discontinuity. The seismic parameters, such as delay, velocity, and attenuation, are then calculated. Finally, the equivalent medium model parameters of the rock mass are computed numerically while taking into account the natural discontinuity distribution. This methodology was applied to 17 bench fronts from six aggregate quarries located in Tunisia, Spain, Austria, and Sweden. It allowed characterizing the rock mass discontinuity network, the resulting seismic performance, and the equivalent medium stiffness. The relationship between the equivalent Young's modulus and rock discontinuity parameters was also analyzed. For these different bench fronts, the proposed numerical approach was also compared to several empirical formulas, based on RQD and fracture density values, published in previous research studies, showing its usefulness and efficiency in estimating rapidly the Young's modulus of equivalent medium for wave propagation analysis.

29 CFR 4041.24 - Notices of plan benefits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... lump sum and the age at which, or form in which, the plan benefits will be paid differs from the normal retirement benefit— (i) The age or form stated in the plan; and (ii) The age or form adjustment factors; and... for the third month before the month in which the lump sum is distributed), a reference to the...

A painful perineal lump: an unusual case of ectopic breast tissue

PubMed Central

Yongue, G; Leff, D; Lamb, BW; Karim, S; Aref, F; Vashisht, R

2011-01-01

We report the case of a 40-year-old lady who presented with an episodically painful perineal lump. Clinical and radiological investigations were inconclusive. Excision biopsy confirmed an ectopic breast mass. Ectopic breast tissue is difficult to diagnose but close attention to clinical findings can help to guide further investigation and diagnosis. PMID:22004627

29 CFR 4044.75 - Other lump sum benefits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sum benefits. The value of a lump sum benefit which is not covered under § 4044.73 or § 4044.74 is equal to— (a) The value under the qualifying bid, if an insurer provides the benefit; or (b) The present value of the benefit as of the date of distribution, determined using reasonable actuarial assumptions...

Nonlinear Wave Propagation

DTIC Science & Technology

2000-03-17

scattering problem has intrinsic interest in its own right. A new class of lump type solutions of the multidimensional Kadomtsev - Petviashvili (KP) equation ...solutions associated with the Kadomtsev - Petviashvili equation have more com- plicated interaction properties than the previously known lump...B-3. New Solutions of the Nonstationary Schrödinger and Kadomtsev - Petviashvili Equations , M.J. Ablowitz and J. Villarroel, in Symmetries and

5 CFR 839.1115 - What is an actuarial reduction?

Code of Federal Regulations, 2010 CFR

2010-01-01

...? An actuarial reduction allows you to receive benefits without having to pay an amount due in a lump sum. OPM reduces your annuity in a way that, on average, allows the Fund to recover the amount of the... have to pay at that time. To compute an actuarial reduction, OPM divides the lump sum amount by the...

5 CFR 839.1115 - What is an actuarial reduction?

Code of Federal Regulations, 2011 CFR

2011-01-01

...? An actuarial reduction allows you to receive benefits without having to pay an amount due in a lump sum. OPM reduces your annuity in a way that, on average, allows the Fund to recover the amount of the... have to pay at that time. To compute an actuarial reduction, OPM divides the lump sum amount by the...

20 CFR 404.1059 - Deemed wages for certain individuals interned during World War II.

Code of Federal Regulations, 2011 CFR

2011-04-01

... the amount of, any lump-sum death payment in the case of a death after December 1972, and for... for a monthly benefit, a recalculation of benefits by reason of this section, or a lump-sum death...) The highest actual hourly rate of pay received for any employment before internment, multiplied by 40...

20 CFR 404.1059 - Deemed wages for certain individuals interned during World War II.

Code of Federal Regulations, 2012 CFR

2012-04-01

... the amount of, any lump-sum death payment in the case of a death after December 1972, and for... for a monthly benefit, a recalculation of benefits by reason of this section, or a lump-sum death...) The highest actual hourly rate of pay received for any employment before internment, multiplied by 40...

20 CFR 404.1059 - Deemed wages for certain individuals interned during World War II.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the amount of, any lump-sum death payment in the case of a death after December 1972, and for... for a monthly benefit, a recalculation of benefits by reason of this section, or a lump-sum death...) The highest actual hourly rate of pay received for any employment before internment, multiplied by 40...

20 CFR 404.1059 - Deemed wages for certain individuals interned during World War II.

Code of Federal Regulations, 2014 CFR

2014-04-01

... the amount of, any lump-sum death payment in the case of a death after December 1972, and for... for a monthly benefit, a recalculation of benefits by reason of this section, or a lump-sum death...) The highest actual hourly rate of pay received for any employment before internment, multiplied by 40...

20 CFR 404.1059 - Deemed wages for certain individuals interned during World War II.

Code of Federal Regulations, 2010 CFR

2010-04-01

... the amount of, any lump-sum death payment in the case of a death after December 1972, and for... for a monthly benefit, a recalculation of benefits by reason of this section, or a lump-sum death...) The highest actual hourly rate of pay received for any employment before internment, multiplied by 40...

Unmasking Diogenes Syndrome

PubMed Central

Nayak, Kashinath; Gopinath, Hima; Kini, Hema; Kumar, Pramod

2015-01-01

Diogenes syndrome is characterized by extreme self-neglect, social withdrawal, and poor personal and domestic hygiene. We report a case of Diogenes syndrome presenting with dermatitis passivata. An unusual “mask” of dirt resembling a carapace, onset of neglect after awareness of a breast lump and resumption of personal grooming and social activities after removal of the lump and counseling were seen. PMID:26120158

Leaks, Lumps, and Lines: Stigma and Women's Bodies

ERIC Educational Resources Information Center

Chrisler, Joan C.

2011-01-01

Women's bodies have often been positioned in art and popular culture as monstrous or defiled and women's bodily products (e.g., menstrual fluid, breast milk) as disgusting. This framing has led to the stigmatization of aspects of women's bodies (e.g., leaking fluids, lumps of fat, and lines in the skin that indicate aging), especially those…

45 CFR 158.241 - Form of rebate.

Code of Federal Regulations, 2014 CFR

2014-10-01

... reimbursement using the same method that was used for payment, such as credit card or direct debit. [75 FR 74921... in the form of a premium credit, lump-sum check, or, if an enrollee paid the premium using a credit card or direct debit, by lump-sum reimbursement to the account used to pay the premium. (2) For each of...

On Structural Equation Model Equivalence.

ERIC Educational Resources Information Center

Raykov, Tenko; Penev, Spiridon

1999-01-01

Presents a necessary and sufficient condition for the equivalence of structural-equation models that is applicable to models with parameter restrictions and models that may or may not fulfill assumptions of the rules. Illustrates the application of the approach for studying model equivalence. (SLD)

Sample size determination for a three-arm equivalence trial of Poisson and negative binomial responses.

PubMed

Chang, Yu-Wei; Tsong, Yi; Zhao, Zhigen

2017-01-01

Assessing equivalence or similarity has drawn much attention recently as many drug products have lost or will lose their patents in the next few years, especially certain best-selling biologics. To claim equivalence between the test treatment and the reference treatment when assay sensitivity is well established from historical data, one has to demonstrate both superiority of the test treatment over placebo and equivalence between the test treatment and the reference treatment. Thus, there is urgency for practitioners to derive a practical way to calculate sample size for a three-arm equivalence trial. The primary endpoints of a clinical trial may not always be continuous, but may be discrete. In this paper, the authors derive power function and discuss sample size requirement for a three-arm equivalence trial with Poisson and negative binomial clinical endpoints. In addition, the authors examine the effect of the dispersion parameter on the power and the sample size by varying its coefficient from small to large. In extensive numerical studies, the authors demonstrate that required sample size heavily depends on the dispersion parameter. Therefore, misusing a Poisson model for negative binomial data may easily lose power up to 20%, depending on the value of the dispersion parameter.

Mathematical, numerical and experimental study in the human aorta with coexisting models of bicuspid aortic stenosis and coarctation of the aorta.

PubMed

Keshavarz-Motamed, Z; Garcia, J; Kadem, L

2011-01-01

Coarctation of the aorta is an obstruction of the aorta and is usually associated with other concomitant cardiovascular abnormalities especially with bicuspid aortic valve stenosis. The objectives of this study are, (1) to investigate the effects of coarctation on the hemodynamics in the aorta to gain a better understanding of the cause of certain post-surgical coarctation problems, (2) to develop and introduce a new lumped parameter model, mainly based on non-invasive data, allowing the description of the interaction between left ventricle, coarctation of the aorta, aortic valve stenosis, and the arterial system.

Modeling of a resonant heat engine

NASA Astrophysics Data System (ADS)

Preetham, B. S.; Anderson, M.; Richards, C.

2012-12-01

A resonant heat engine in which the piston assembly is replaced by a sealed elastic cavity is modeled and analyzed. A nondimensional lumped-parameter model is derived and used to investigate the factors that control the performance of the engine. The thermal efficiency predicted by the model agrees with that predicted from the relation for the Otto cycle based on compression ratio. The predictions show that for a fixed mechanical load, increasing the heat input results in increased efficiency. The output power and power density are shown to depend on the loading for a given heat input. The loading condition for maximum output power is different from that required for maximum power density.

A factory concept for processing and manufacturing with lunar material

NASA Technical Reports Server (NTRS)

Driggers, G. W.

1977-01-01

A conceptual design for an orbital factory sized to process 1.5 million metric tons per year of raw lunar fines into 0.3 million metric tons of manufacturing materials is presented. A conservative approach involving application of present earth-based technology leads to a design devoid of new inventions. Earth based counterparts to the factory machinery were used to generate subsystem masses and lumped parameters for volume and mass estimates. The results are considered to be conservative since technologies more advanced than those assumed are presently available in many areas. Some attributes of potential space processing technologies applied to material refinement and component manufacture are discussed.

Controlling flexible structures with second order actuator dynamics

NASA Technical Reports Server (NTRS)

Inman, Daniel J.; Umland, Jeffrey W.; Bellos, John

1989-01-01

The control of flexible structures for those systems with actuators that are modeled by second order dynamics is examined. Two modeling approaches are investigated. First a stability and performance analysis is performed using a low order finite dimensional model of the structure. Secondly, a continuum model of the flexible structure to be controlled, coupled with lumped parameter second order dynamic models of the actuators performing the control is used. This model is appropriate in the modeling of the control of a flexible panel by proof-mass actuators as well as other beam, plate and shell like structural numbers. The model is verified with experimental measurements.

Conversion and matched filter approximations for serial minimum-shift keyed modulation

NASA Technical Reports Server (NTRS)

Ziemer, R. E.; Ryan, C. R.; Stilwell, J. H.

1982-01-01

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Low-pass implementations of these filters as parallel inphase- and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of .000001.

Building Thermal Models

NASA Technical Reports Server (NTRS)

Peabody, Hume L.

2017-01-01

This presentation is meant to be an overview of the model building process It is based on typical techniques (Monte Carlo Ray Tracing for radiation exchange, Lumped Parameter, Finite Difference for thermal solution) used by the aerospace industry This is not intended to be a "How to Use ThermalDesktop" course. It is intended to be a "How to Build Thermal Models" course and the techniques will be demonstrated using the capabilities of ThermalDesktop (TD). Other codes may or may not have similar capabilities. The General Model Building Process can be broken into four top level steps: 1. Build Model; 2. Check Model; 3. Execute Model; 4. Verify Results.

Inferring transit time distributions from atmospheric tracer data: Assessment of the predictive capacities of Lumped Parameter Models on a 3D crystalline aquifer model

NASA Astrophysics Data System (ADS)

Marçais, J.; de Dreuzy, J.-R.; Ginn, T. R.; Rousseau-Gueutin, P.; Leray, S.

2015-06-01

While central in groundwater resources and contaminant fate, Transit Time Distributions (TTDs) are never directly accessible from field measurements but always deduced from a combination of tracer data and more or less involved models. We evaluate the predictive capabilities of approximate distributions (Lumped Parameter Models abbreviated as LPMs) instead of fully developed aquifer models. We develop a generic assessment methodology based on synthetic aquifer models to establish references for observable quantities as tracer concentrations and prediction targets as groundwater renewal times. Candidate LPMs are calibrated on the observable tracer concentrations and used to infer renewal time predictions, which are compared with the reference ones. This methodology is applied to the produced crystalline aquifer of Plœmeur (Brittany, France) where flows leak through a micaschists aquitard to reach a sloping aquifer where they radially converge to the producing well, issuing broad rather than multi-modal TTDs. One, two and three parameters LPMs were calibrated to a corresponding number of simulated reference anthropogenic tracer concentrations (CFC-11, 85Kr and SF6). Extensive statistical analysis over the aquifer shows that a good fit of the anthropogenic tracer concentrations is neither a necessary nor a sufficient condition to reach acceptable predictive capability. Prediction accuracy is however strongly conditioned by the use of a priori relevant LPMs. Only adequate LPM shapes yield unbiased estimations. In the case of Plœmeur, relevant LPMs should have two parameters to capture the mean and the standard deviation of the residence times and cover the first few decades [0; 50 years]. Inverse Gaussian and shifted exponential performed equally well for the wide variety of the reference TTDs from strongly peaked in recharge zones where flows are diverging to broadly distributed in more converging zones. When using two sufficiently different atmospheric tracers like CFC-11 and 85Kr, groundwater renewal time predictions are accurate at 1-5 years for estimating mean transit times of some decades (10-50 years). 1-parameter LPMs calibrated on a single atmospheric tracer lead to substantially larger errors of the order of 10 years, while 3-parameter LPMs calibrated with a third atmospheric tracers (SF6) do not improve the prediction capabilities. Based on a specific site, this study highlights the high predictive capacities of two atmospheric tracers on the same time range with sufficiently different atmospheric concentration chronicles.

A Bayesian Uncertainty Framework for Conceptual Snowmelt and Hydrologic Models Applied to the Tenderfoot Creek Experimental Forest

NASA Astrophysics Data System (ADS)

Smith, T.; Marshall, L.

2007-12-01

In many mountainous regions, the single most important parameter in forecasting the controls on regional water resources is snowpack (Williams et al., 1999). In an effort to bridge the gap between theoretical understanding and functional modeling of snow-driven watersheds, a flexible hydrologic modeling framework is being developed. The aim is to create a suite of models that move from parsimonious structures, concentrated on aggregated watershed response, to those focused on representing finer scale processes and distributed response. This framework will operate as a tool to investigate the link between hydrologic model predictive performance, uncertainty, model complexity, and observable hydrologic processes. Bayesian methods, and particularly Markov chain Monte Carlo (MCMC) techniques, are extremely useful in uncertainty assessment and parameter estimation of hydrologic models. However, these methods have some difficulties in implementation. In a traditional Bayesian setting, it can be difficult to reconcile multiple data types, particularly those offering different spatial and temporal coverage, depending on the model type. These difficulties are also exacerbated by sensitivity of MCMC algorithms to model initialization and complex parameter interdependencies. As a way of circumnavigating some of the computational complications, adaptive MCMC algorithms have been developed to take advantage of the information gained from each successive iteration. Two adaptive algorithms are compared is this study, the Adaptive Metropolis (AM) algorithm, developed by Haario et al (2001), and the Delayed Rejection Adaptive Metropolis (DRAM) algorithm, developed by Haario et al (2006). While neither algorithm is truly Markovian, it has been proven that each satisfies the desired ergodicity and stationarity properties of Markov chains. Both algorithms were implemented as the uncertainty and parameter estimation framework for a conceptual rainfall-runoff model based on the Probability Distributed Model (PDM), developed by Moore (1985). We implement the modeling framework in Stringer Creek watershed in the Tenderfoot Creek Experimental Forest (TCEF), Montana. The snowmelt-driven watershed offers that additional challenge of modeling snow accumulation and melt and current efforts are aimed at developing a temperature- and radiation-index snowmelt model. Auxiliary data available from within TCEF's watersheds are used to support in the understanding of information value as it relates to predictive performance. Because the model is based on lumped parameters, auxiliary data are hard to incorporate directly. However, these additional data offer benefits through the ability to inform prior distributions of the lumped, model parameters. By incorporating data offering different information into the uncertainty assessment process, a cross-validation technique is engaged to better ensure that modeled results reflect real process complexity.

Methodological questions of creating tissue-equivalent phantoms

NASA Technical Reports Server (NTRS)

Kolodkin, A. V.; Popov, V. I.; Sychkov, M. A.; Nikl, I.; Erdei, M.; Eyben, O.

1974-01-01

On the basis of analysis and generalization of literature data, the composition of tissue equivalent plastic was justified, parameters of a standard man were determined, plaster and metal forms were created for casting dummies, and an experimental model was produced from tissue equivalent material.

CHAMP and GRACE Resonances and the Gravity Field of the Earth

NASA Astrophysics Data System (ADS)

Gooding, R. H.; Wagner, C. A.; Klokocnik, J.; Kostelecky, J.

With the far more precise orbits of CHAMP and GRACE today than was the standard 2-3 decades ago there was and is an unprecedented opportunity for determining precise and valuable values of certain lumped geopotential harmonic coefficients of selected orders independently of comprehensive gravity field models via the recently revived technique that capitalizes on the resonant variation of appropriate orbital elements the inclination in particular Here we first identify important resonances during the lifetime of CHAMP and GRACE in terms of the decaying semimajor axis these being 46 3 77 5 31 2 78 5 and 47 3 for CHAMP and 61 4 for GRACE Then we analyze state vectors for CHAMP and TLE for GRACE A from GFZ and determined the relevant lumped coefficients To increase its lifetime the CHAMP satellite orbit was raised twice in June and December 2002 so CHAMP passed through 31 2 resonance three times More accurate values for these coefficients are obtained than originally and the precision for the 62 4 overtone resonance implicit in 31 2 is striking comparable to that for 31 2 Most recently CHAMP passed throughout the 47 3 resonance yielding the opportunity to determine new lumped coefficients For GRACE we have no state vectors and have to work with the TLE only nevertheless we have lumped coefficients of 61st order from its strong 61 4 resonance In each case the resonant lumped values are compared with those derivable from various global gravity models We thereby confirm the continuing power of the resonance technique

Reproducing the nonlinear dynamic behavior of a structured beam with a generalized continuum model

NASA Astrophysics Data System (ADS)

Vila, J.; Fernández-Sáez, J.; Zaera, R.

2018-04-01

In this paper we study the coupled axial-transverse nonlinear vibrations of a kind of one dimensional structured solids by application of the so called Inertia Gradient Nonlinear continuum model. To show the accuracy of this axiomatic model, previously proposed by the authors, its predictions are compared with numeric results from a previously defined finite discrete chain of lumped masses and springs, for several number of particles. A continualization of the discrete model equations based on Taylor series allowed us to set equivalent values of the mechanical properties in both discrete and axiomatic continuum models. Contrary to the classical continuum model, the inertia gradient nonlinear continuum model used herein is able to capture scale effects, which arise for modes in which the wavelength is comparable to the characteristic distance of the structured solid. The main conclusion of the work is that the proposed generalized continuum model captures the scale effects in both linear and nonlinear regimes, reproducing the behavior of the 1D nonlinear discrete model adequately.

Simulation of 100-300 GHz solid-state harmonic sources

NASA Technical Reports Server (NTRS)

Zybura, Michael F.; Jones, J. Robert; Jones, Stephen H.; Tait, Gregory B.

1995-01-01

Accurate and efficient simulations of the large-signal time-dependent characteristics of second-harmonic Transferred Electron Oscillators (TEO's) and Heterostructure Barrier Varactor (HBV) frequency triplers have been obtained. This is accomplished by using a novel and efficient harmonic-balance circuit analysis technique which facilitates the integration of physics-based hydrodynamic device simulators. The integrated hydrodynamic device/harmonic-balance circuit simulators allow TEO and HBV circuits to be co-designed from both a device and a circuit point of view. Comparisons have been made with published experimental data for both TEO's and HBV's. For TEO's, excellent correlation has been obtained at 140 GHz and 188 GHz in second-harmonic operation. Excellent correlation has also been obtained for HBV frequency triplers operating near 200 GHz. For HBV's, both a lumped quasi-static equivalent circuit model and the hydrodynamic device simulator have been linked to the harmonic-balance circuit simulator. This comparison illustrates the importance of representing active devices with physics-based numerical device models rather than analytical device models.

Verification and Validation of the New Dynamic Mooring Modules Available in FAST v8: Preprint

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

Wendt, Fabian; Robertson, Amy; Jonkman, Jason

2016-08-01

The open-source aero-hydro-servo-elastic wind turbine simulation software, FAST v8, was recently coupled to two newly developed mooring dynamics modules: MoorDyn and FEAMooring. MoorDyn is a lumped-mass-based mooring dynamics module developed by the University of Maine, and FEAMooring is a finite-element-based mooring dynamics module developed by Texas A&M University. This paper summarizes the work performed to verify and validate these modules against other mooring models and measured test data to assess their reliability and accuracy. The quality of the fairlead load predictions by the open-source mooring modules MoorDyn and FEAMooring appear to be largely equivalent to what is predicted by themore » commercial tool OrcaFlex. Both mooring dynamic model predictions agree well with the experimental data, considering the given limitations in the accuracy of the platform hydrodynamic load calculation and the quality of the measurement data.« less

Verification and Validation of the New Dynamic Mooring Modules Available in FAST v8

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

Wendt, Fabian F.; Andersen, Morten T.; Robertson, Amy N.

2016-07-01

The open-source aero-hydro-servo-elastic wind turbine simulation software, FAST v8, was recently coupled to two newly developed mooring dynamics modules: MoorDyn and FEAMooring. MoorDyn is a lumped-mass-based mooring dynamics module developed by the University of Maine, and FEAMooring is a finite-element-based mooring dynamics module developed by Texas A&M University. This paper summarizes the work performed to verify and validate these modules against other mooring models and measured test data to assess their reliability and accuracy. The quality of the fairlead load predictions by the open-source mooring modules MoorDyn and FEAMooring appear to be largely equivalent to what is predicted by themore » commercial tool OrcaFlex. Both mooring dynamic model predictions agree well with the experimental data, considering the given limitations in the accuracy of the platform hydrodynamic load calculation and the quality of the measurement data.« less

A Compact Multiple Notched Ultra-Wide Band Antenna with an Analysis of the CSRR-TO-CSRR Coupling for Portable UWB Applications.

PubMed

Rahman, MuhibUr; Ko, Dong-Sik; Park, Jung-Dong

2017-09-25

We present a compact ultra-wideband (UWB) antenna integrated with sharp notches with a detailed analysis of the mutual coupling of the multiple notch resonators. By utilizing complementary split ring resonators (CSRR) on the radiating semi-circular patch, we achieve the sharp notch-filtering of various bands within the UWB band without increasing the antenna size. The notched frequency bands include WiMAX, INSAT, and lower and upper WLAN. In order to estimate the frequency shifts of the notch due to the coupling of the nearby CSRRs, an analysis of the coupling among the multiple notch resonators is carried out and we construct the lumped-circuit equivalent model. The time domain analysis of the proposed antenna is performed to show its validity on the UWB application. The measured frequency response of the input port corresponds quite well with the calculations and simulations. The radiation pattern of the implemented quad-notched UWB antenna is nearly omnidirectional in the passband.

A Compact Multiple Notched Ultra-Wide Band Antenna with an Analysis of the CSRR-TO-CSRR Coupling for Portable UWB Applications

PubMed Central

Ko, Dong-Sik

2017-01-01

We present a compact ultra-wideband (UWB) antenna integrated with sharp notches with a detailed analysis of the mutual coupling of the multiple notch resonators. By utilizing complementary split ring resonators (CSRR) on the radiating semi-circular patch, we achieve the sharp notch-filtering of various bands within the UWB band without increasing the antenna size. The notched frequency bands include WiMAX, INSAT, and lower and upper WLAN. In order to estimate the frequency shifts of the notch due to the coupling of the nearby CSRRs, an analysis of the coupling among the multiple notch resonators is carried out and we construct the lumped-circuit equivalent model. The time domain analysis of the proposed antenna is performed to show its validity on the UWB application. The measured frequency response of the input port corresponds quite well with the calculations and simulations. The radiation pattern of the implemented quad-notched UWB antenna is nearly omnidirectional in the passband. PMID:28946658

On the relationship between wave based control, absolute vibration suppression and input shaping

NASA Astrophysics Data System (ADS)

Peled, I.; O'Connor, W. J.; Halevi, Y.

2013-08-01

The modeling and control of continuous flexible structures is one of the most challenging problems in control theory. This topic gains more interest with the development of slender space structures, light weight aeronautical components or even traditional gears and drive shafts with flexible properties. Several control schemes are based on the traveling wave approach, rather than the more common modal methods. In this work we investigate the relationships between two of these methods. The Absolute Vibration Suppression (AVS) controller, which was developed for infinite dimension systems, is compared to Wave Based Control (WBC) which was designed primarily for lumped systems. The WBC was first adjusted to continuous systems and then the two controllers, whose algorithms seem different, are compared. The investigation shows that for the flexible shaft these two control laws are actually the same. Furthermore, when converted into an equivalent open loop controller they appear as an extension to continuous systems of the Input Shaping (IS) methodology.

77 FR 69665 - Agency Forms Submitted for OMB Review, Request for Comments

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-20

...), benefits that may be due on the death of a railroad employee or a survivor annuitant include (1) a lump-sum death benefit (2) a residual lump-sum payment (3) accrued annuities due but unpaid at death, and (4... notification of the death of a railroad employee or survivor annuitant, an RRB field office utilizes Form RL-94...

76 FR 35110 - Federal Travel Regulation (FTR); Miscellaneous Expense Allowance (MEA)

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-16

... Management Policy, at (202) 501-3822 or e-mail at [email protected] . Please cite FTR Amendment 2011-02... immediate family is automatically entitled to a lump-sum of one week's basic gross pay, up to $500, and an employee with an immediate family is entitled to a lump-sum of two weeks' basic gross pay, up to $1000. If...

36 CFR 223.64 - Appraisal on a lump-sum value or rate per unit of measure basis.

Code of Federal Regulations, 2010 CFR

2010-07-01

... costs or selling values subsequent to the rate redetermination which reduce conversion value to less... or rate per unit of measure basis. 223.64 Section 223.64 Parks, Forests, and Public Property FOREST... Contracts Appraisal and Pricing § 223.64 Appraisal on a lump-sum value or rate per unit of measure basis...

42 CFR 137.65 - May a Self-Governance Tribe receive statutorily mandated grant funding in an annual lump sum...

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false May a Self-Governance Tribe receive statutorily mandated grant funding in an annual lump sum advance payment? 137.65 Section 137.65 Public Health PUBLIC... HUMAN SERVICES TRIBAL SELF-GOVERNANCE Statutorily Mandated Grants § 137.65 May a Self-Governance Tribe...

Path lumping: An efficient algorithm to identify metastable path channels for conformational dynamics of multi-body systems

NASA Astrophysics Data System (ADS)

Meng, Luming; Sheong, Fu Kit; Zeng, Xiangze; Zhu, Lizhe; Huang, Xuhui

2017-07-01

Constructing Markov state models from large-scale molecular dynamics simulation trajectories is a promising approach to dissect the kinetic mechanisms of complex chemical and biological processes. Combined with transition path theory, Markov state models can be applied to identify all pathways connecting any conformational states of interest. However, the identified pathways can be too complex to comprehend, especially for multi-body processes where numerous parallel pathways with comparable flux probability often coexist. Here, we have developed a path lumping method to group these parallel pathways into metastable path channels for analysis. We define the similarity between two pathways as the intercrossing flux between them and then apply the spectral clustering algorithm to lump these pathways into groups. We demonstrate the power of our method by applying it to two systems: a 2D-potential consisting of four metastable energy channels and the hydrophobic collapse process of two hydrophobic molecules. In both cases, our algorithm successfully reveals the metastable path channels. We expect this path lumping algorithm to be a promising tool for revealing unprecedented insights into the kinetic mechanisms of complex multi-body processes.

BioMOL: a computer-assisted biological modeling tool for complex chemical mixtures and biological processes at the molecular level.

PubMed Central

Klein, Michael T; Hou, Gang; Quann, Richard J; Wei, Wei; Liao, Kai H; Yang, Raymond S H; Campain, Julie A; Mazurek, Monica A; Broadbelt, Linda J

2002-01-01

A chemical engineering approach for the rigorous construction, solution, and optimization of detailed kinetic models for biological processes is described. This modeling capability addresses the required technical components of detailed kinetic modeling, namely, the modeling of reactant structure and composition, the building of the reaction network, the organization of model parameters, the solution of the kinetic model, and the optimization of the model. Even though this modeling approach has enjoyed successful application in the petroleum industry, its application to biomedical research has just begun. We propose to expand the horizons on classic pharmacokinetics and physiologically based pharmacokinetics (PBPK), where human or animal bodies were often described by a few compartments, by integrating PBPK with reaction network modeling described in this article. If one draws a parallel between an oil refinery, where the application of this modeling approach has been very successful, and a human body, the individual processing units in the oil refinery may be considered equivalent to the vital organs of the human body. Even though the cell or organ may be much more complicated, the complex biochemical reaction networks in each organ may be similarly modeled and linked in much the same way as the modeling of the entire oil refinery through linkage of the individual processing units. The integrated chemical engineering software package described in this article, BioMOL, denotes the biological application of molecular-oriented lumping. BioMOL can build a detailed model in 1-1,000 CPU sec using standard desktop hardware. The models solve and optimize using standard and widely available hardware and software and can be presented in the context of a user-friendly interface. We believe this is an engineering tool with great promise in its application to complex biological reaction networks. PMID:12634134

A new modal superposition method for nonlinear vibration analysis of structures using hybrid mode shapes

NASA Astrophysics Data System (ADS)

Ferhatoglu, Erhan; Cigeroglu, Ender; Özgüven, H. Nevzat

2018-07-01

In this paper, a new modal superposition method based on a hybrid mode shape concept is developed for the determination of steady state vibration response of nonlinear structures. The method is developed specifically for systems having nonlinearities where the stiffness of the system may take different limiting values. Stiffness variation of these nonlinear systems enables one to define different linear systems corresponding to each value of the limiting equivalent stiffness. Moreover, the response of the nonlinear system is bounded by the confinement of these linear systems. In this study, a modal superposition method utilizing novel hybrid mode shapes which are defined as linear combinations of the modal vectors of the limiting linear systems is proposed to determine periodic response of nonlinear systems. In this method the response of the nonlinear system is written in terms of hybrid modes instead of the modes of the underlying linear system. This provides decrease of the number of modes that should be retained for an accurate solution, which in turn reduces the number of nonlinear equations to be solved. In this way, computational time for response calculation is directly curtailed. In the solution, the equations of motion are converted to a set of nonlinear algebraic equations by using describing function approach, and the numerical solution is obtained by using Newton's method with arc-length continuation. The method developed is applied on two different systems: a lumped parameter model and a finite element model. Several case studies are performed and the accuracy and computational efficiency of the proposed modal superposition method with hybrid mode shapes are compared with those of the classical modal superposition method which utilizes the mode shapes of the underlying linear system.

Nodular Fasciitis of the Breast Previously Misdiagnosed as Breast Carcinoma

PubMed Central

Ozben, Volkan; Aydogan, Fatih; Karaca, Fatih Can; Ilvan, Sennur; Uras, Cihan

2009-01-01

Summary Background Nodular fasciitis of the breast is a rare benign pathology that can mimic breast cancer clinically, radiologically, and histopathologically. Case Report An 18-year-old female patient had first visited a physician in a different center with the complaint of a lump in her left breast. Breast examination had revealed a palpable mass located in the left upper outer quadrant. Ultrasonography had demonstrated a hypoechoic lesion. Excisional biopsy of the lump had been performed and histopathologic examination misdiagnosed this lump as a mesenchymal tumor. The patient was then referred to our clinic for further investigations. Pathologic revision was performed and the diagnosis of nodular fasciitis of the breast was established. Conclusion Awareness of this rare clinical entity, nodular fasciitis, in the breast eliminates the misdiagnosis of breast cancer. PMID:20877676

Certainty Equivalence M-MRAC for Systems with Unmatched Uncertainties

NASA Technical Reports Server (NTRS)

Stepanyan, Vahram; Krishnakumar, Kalmanje

2012-01-01

The paper presents a certainty equivalence state feedback indirect adaptive control design method for the systems of any relative degree with unmatched uncertainties. The approach is based on the parameter identification (estimation) model, which is completely separated from the control design and is capable of producing parameter estimates as fast as the computing power allows without generating high frequency oscillations. It is shown that the system's input and output tracking errors can be systematically decreased by the proper choice of the design parameters.

A theoretical model for investigating the effect of vacuum fluctuations on the electromechanical stability of nanotweezers

NASA Astrophysics Data System (ADS)

Farrokhabadi, A.; Mokhtari, J.; Koochi, A.; Abadyan, M.

2015-06-01

In this paper, the impact of the Casimir attraction on the electromechanical stability of nanowire-fabricated nanotweezers is investigated using a theoretical continuum mechanics model. The Dirichlet mode is considered and an asymptotic solution, based on path integral approach, is applied to consider the effect of vacuum fluctuations in the model. The Euler-Bernoulli beam theory is employed to derive the nonlinear governing equation of the nanotweezers. The governing equations are solved by three different approaches, i.e. the modified variation iteration method, generalized differential quadrature method and using a lumped parameter model. Various perspectives of the problem, including the comparison with the van der Waals force regime, the variation of instability parameters and effects of geometry are addressed in present paper. The proposed approach is beneficial for the precise determination of the electrostatic response of the nanotweezers in the presence of Casimir force.

Understanding Lymphatic Valve Function via Computational Modeling

NASA Astrophysics Data System (ADS)

Wolf, Ki; Nepiyushchikh, Zhanna; Razavi, Mohammad; Dixon, Brandon; Alexeev, Alexander

2017-11-01

The lymphatic system is a crucial part to the circulatory system with many important functions, such as transport of interstitial fluid, fatty acid, and immune cells. Lymphatic vessels' contractile walls and valves allow lymph flow against adverse pressure gradients and prevent back flow. Yet, the effect of lymphatic valves' geometric and mechanical properties to pumping performance and lymphatic dysfunctions like lymphedema is not well understood. Our coupled fluid-solid computational model based on lattice Boltzmann model and lattice spring model investigates the dynamics and effectiveness of lymphatic valves in resistance minimization, backflow prevention, and viscoelastic response under different geometric and mechanical properties, suggesting the range of lymphatic valve parameters with effective pumping performance. Our model also provides more physiologically relevant relations of the valve response under varied conditions to a lumped parameter model of the lymphatic system giving an integrative insight into lymphatic system performance, including its failure due to diseases. NSF CMMI-1635133.

Genetic particle swarm parallel algorithm analysis of optimization arrangement on mistuned blades

NASA Astrophysics Data System (ADS)

Zhao, Tianyu; Yuan, Huiqun; Yang, Wenjun; Sun, Huagang

2017-12-01

This article introduces a method of mistuned parameter identification which consists of static frequency testing of blades, dichotomy and finite element analysis. A lumped parameter model of an engine bladed-disc system is then set up. A bladed arrangement optimization method, namely the genetic particle swarm optimization algorithm, is presented. It consists of a discrete particle swarm optimization and a genetic algorithm. From this, the local and global search ability is introduced. CUDA-based co-evolution particle swarm optimization, using a graphics processing unit, is presented and its performance is analysed. The results show that using optimization results can reduce the amplitude and localization of the forced vibration response of a bladed-disc system, while optimization based on the CUDA framework can improve the computing speed. This method could provide support for engineering applications in terms of effectiveness and efficiency.

Distributed parameter statics of magnetic catheters.

PubMed

Tunay, Ilker

2011-01-01

We discuss how to use special Cosserat rod theory for deriving distributed-parameter static equilibrium equations of magnetic catheters. These medical devices are used for minimally-invasive diagnostic and therapeutic procedures and can be operated remotely or controlled by automated algorithms. The magnetic material can be lumped in rigid segments or distributed in flexible segments. The position vector of the cross-section centroid and quaternion representation of an orthonormal triad are selected as DOF. The strain energy for transversely isotropic, hyperelastic rods is augmented with the mechanical potential energy of the magnetic field and a penalty term to enforce the quaternion unity constraint. Numerical solution is found by 1D finite elements. Material properties of polymer tubes in extension, bending and twist are determined by mechanical and magnetic experiments. Software experiments with commercial FEM software indicate that the computational effort with the proposed method is at least one order of magnitude less than standard 3D FEM.

An Overview of the GIS Weasel

USGS Publications Warehouse

Viger, Roland J.

2008-01-01

This fact sheet provides a high-level description of the GIS Weasel, a software system designed to aid users in preparing spatial information as input to lumped and distributed parameter environmental simulation models (ESMs). The GIS Weasel provides geographic information system (GIS) tools to help create maps of geographic features relevant to the application of a user?s ESM and to generate parameters from those maps. The operation of the GIS Weasel does not require a user to be a GIS expert, only that a user has an understanding of the spatial information requirements of the model. The GIS Weasel software system provides a GIS-based graphical user interface (GUI), C programming language executables, and general utility scripts. The software will run on any computing platform where ArcInfo Workstation (version 8.1 or later) and the GRID extension are accessible. The user controls the GIS Weasel by interacting with menus, maps, and tables.

Investigation of chaos and its control in a Duffing-type nano beam model

NASA Astrophysics Data System (ADS)

Jha, Abhishek Kumar; Dasgupta, Sovan Sundar

2018-04-01

The prediction of chaos of a nano beam with harmonic excitation is investigated. Using the Galerkin method the nonlinear lumped model of a clamped-clamped nano beam with nonlinear cubic stiffness is obtained. This is a Duffing system with hardening type of nonlinearity. Based on the energy function and the phase portrait of the system, the resonator dynamics is categorized into four situations in which Using Malnikov function, an analytical criterion for homoclinic intersection in the form of inequality is written in terms of the system parameters. A numerical study including largest lyapunov exponent, Poincare diagram and phase portrait confirm the analytical prediction of chaos and effect of forcing amplitude. Subsequently, a linear velocity feedback controller is introduced into the system to successfully control the chaotic motion of the system at a faster rate at larger value of gain parameter.

Study of a two-bed silica gel-water adsorption chiller: performance analysis

NASA Astrophysics Data System (ADS)

Sah, Ramesh P.; Choudhury, Biplab; Das, Ranadip K.

2018-01-01

In this study, a lumped parameter simulation model has been developed for analysis of the thermal performance of a single-stage two-bed adsorption chiller. Since silica gel has low regeneration temperature and water has high latent heat of vaporisation, silica gel-water pair has been chosen as the working pair of the adsorption chiller. Low-grade waste heat or solar heat at around 70-80°C can be used to run this adsorption chiller. In this model, the effects of operating parameters on the performance of the chiller have been studied. The simulated results show that the cooling capacity of the chiller has an optimum value of 5.95 kW for a cycle time of 1600 s with the hot, cooling, and chilled water inlet temperatures at 85°C, 25°C, and 14°C, respectively. The present model can be utilised to investigate and optimise adsorption chillers.

Modelling of deformation process for the layer of elastoviscoplastic media under surface action of periodic force of arbitrary type

NASA Astrophysics Data System (ADS)

Mikheyev, V. V.; Saveliev, S. V.

2018-01-01

Description of deflected mode for different types of materials under action of external force plays special role for wide variety of applications - from construction mechanics to circuits engineering. This article con-siders the problem of plastic deformation of the layer of elastoviscolastic soil under surface periodic force. The problem was solved with use of the modified lumped parameters approach which takes into account close to real distribution of normal stress in the depth of the layer along with changes in local mechanical properties of the material taking place during plastic deformation. Special numeric algorithm was worked out for computer modeling of the process. As an example of application suggested algorithm was realized for the deformation of the layer of elasoviscoplastic material by the source of external lateral force with the parameters of real technological process of soil compaction.

Equivalent Circuit Parameter Calculation of Interior Permanent Magnet Motor Involving Iron Loss Resistance Using Finite Element Method

NASA Astrophysics Data System (ADS)

Yamazaki, Katsumi

In this paper, we propose a method to calculate the equivalent circuit parameters of interior permanent magnet motors including iron loss resistance using the finite element method. First, the finite element analysis considering harmonics and magnetic saturation is carried out to obtain time variations of magnetic fields in the stator and the rotor core. Second, the iron losses of the stator and the rotor are calculated from the results of the finite element analysis with the considerations of harmonic eddy current losses and the minor hysteresis losses of the core. As a result, we obtain the equivalent circuit parameters i.e. the d-q axis inductance and the iron loss resistance as functions of operating condition of the motor. The proposed method is applied to an interior permanent magnet motor to calculate the characteristics based on the equivalent circuit obtained by the proposed method. The calculated results are compared with the experimental results to verify the accuracy.

Using lumped modelling for providing simple metrics and associated uncertainties of catchment response to agricultural-derived nitrates pollutions

NASA Astrophysics Data System (ADS)

RUIZ, L.; Fovet, O.; Faucheux, M.; Molenat, J.; Sekhar, M.; Aquilina, L.; Gascuel-odoux, C.

2013-12-01

The development of simple and easily accessible metrics is required for characterizing and comparing catchment response to external forcings (climate or anthropogenic) and for managing water resources. The hydrological and geochemical signatures in the stream represent the integration of the various processes controlling this response. The complexity of these signatures over several time scales from sub-daily to several decades [Kirchner et al., 2001] makes their deconvolution very difficult. A large range of modeling approaches intent to represent this complexity by accounting for the spatial and/or temporal variability of the processes involved. However, simple metrics are not easily retrieved from these approaches, mostly because of over-parametrization issues. We hypothesize that to obtain relevant metrics, we need to use models that are able to simulate the observed variability of river signatures at different time scales, while being as parsimonious as possible. The lumped model ETNA (modified from[Ruiz et al., 2002]) is able to simulate adequately the seasonal and inter-annual patterns of stream NO3 concentration. Shallow groundwater is represented by two linear stores with double porosity and riparian processes are represented by a constant nitrogen removal function. Our objective was to identify simple metrics of catchment response by calibrating this lumped model on two paired agricultural catchments where both N inputs and outputs were monitored for a period of 20 years. These catchments, belonging to ORE AgrHys, although underlain by the same granitic bedrock are displaying contrasted chemical signatures. The model was able to simulate the two contrasted observed patterns in stream and groundwater, both on hydrology and chemistry, and at the seasonal and pluri-annual scales. It was also compatible with the expected trends of nitrate concentration since 1960. The output variables of the model were used to compute the nitrate residence time in both the catchments. We used the Global Likelihood Uncertainty Estimations (GLUE) approach [Beven and Binley, 1992] to assess the parameter uncertainties and the subsequent error in model outputs and residence times. Reasonably low parameter uncertainties were obtained by calibrating simultaneously the two paired catchments with two outlets time series of stream flow and nitrate concentrations. Finally, only one parameter controlled the contrast in nitrogen residence times between the catchments. Therefore, this approach provided a promising metric for classifying the variability of catchment response to agricultural nitrogen inputs. Beven, K., and A. Binley (1992), THE FUTURE OF DISTRIBUTED MODELS - MODEL CALIBRATION AND UNCERTAINTY PREDICTION, Hydrological Processes, 6(3), 279-298. Kirchner, J. W., X. Feng, and C. Neal (2001), Catchment-scale advection and dispersion as a mechanism for fractal scaling in stream tracer concentrations, Journal of Hydrology, 254(1-4), 82-101. Ruiz, L., S. Abiven, C. Martin, P. Durand, V. Beaujouan, and J. Molenat (2002), Effect on nitrate concentration in stream water of agricultural practices in small catchments in Brittany : II. Temporal variations and mixing processes, Hydrology and Earth System Sciences, 6(3), 507-513.

Dating of young groundwater using tritium and gaseous tracers (SF6, SF5CF3, CFC-12, H-1301): case study from southern Poland

NASA Astrophysics Data System (ADS)

Rozanski, Kazimierz; Bartyzel, Jakub; Dulinski, Marek; Kuc, Tadeusz; Sliwka, Ireneusz; Mochalski, Pawel; Kania, Jaroslaw; Witczak, Stanislaw

2013-04-01

Groundwater is an important source of potable water in many countries. While it covers ca. 50% of the global drinking water needs, in Europe this share is even higher, reaching approximately 70%. Nowadays, this strategic resource is at risk due to anthropogenic pollutants of various nature entering shallow aquifers. Proper management of groundwater resources requires thorough understanding of groundwater dynamics on time scales characteristic for the history of pollutant input to groundwater. The bomb-tritium has been used for several decades now as a tracer of choice to detect recent recharge and to quantify groundwater residence times on time scales extending from several years to several decades. The lumped-parameter modeling was the most often employed approach in this context. Since nowadays atmospheric concentrations of tritium are approaching natural levels in most parts of the world, the usage of this tracer has become more problematic. Therefore, there is a growing interest in alternative indicators of groundwater age in shallow aquifers. Anthropogenic trace gases present in the atmosphere, such as freons (CFC-11, CFC-12, CFC-113) and sulfur hexafluoride (SF6), have been applied in numerous case studies as substitutes of tritium. Here we present the results of a comprehensive study aimed at quantifying mean residence time of groundwater in the recharge area of porous sandy aquifer system located in the southern Poland. The principal economic role of the aquifer, consisting of two water-bearing strata, is to provide potable water for public and private users. The yield of the aquifer is insufficient to meet all the needs and, as a consequence, licensing conflicts arise between water supply companies and industry on the amount of water available for safe exploitation. To quantify residence time distribution (RTD) functions of water parcels arriving at the production wells located in the recharge area of the aquifer, tritium along with several gaseous tracers was employed. Apart of well-established tracers such as SF6 and CFC-12, also other trace gases present in the atmosphere (SF5CF3 and H-1301) were tested as age indicators of young groundwater. Time series of tracer concentrations in the sampled boreholes were interpreted with the aid of lumped-parameter models. In parallel, the arrival times of tracers to the selected wells were calculated with the aid of 3D flow and transport model available for the studied groundwater system and compared with the RTD functions obtained from lumped-parameter modeling. Acknowledgements. Partial financial support of this work through GENESIS project (http:/www.thegenesisproject.eu) funded by the European Commission 7FP contract 226536 and through the funds from the Polish Ministry of Science and High Education (projects Nr. N N525 362637 and 11.11.220.01) is kindly acknowledged.