Gender bias in the force concept inventory?
Dietz, R. D.; Pearson, R. H.; Semak, M. R.; Willis, C. W.
2012-02-01
Could the well-established fact that males tend to score higher than females on the Force Concept Inventory (FCI) be due to gender bias in the questions? The eventual answer to the question hinges on the definition of bias. We assert that a question is biased only if a factor other than ability (in this case gender) affects the likelihood that a student will answer the question correctly. The statistical technique of differential item functioning allows us to control for ability in our analysis of student performance on each of the thirty FCI questions. This method uses the total score on the FCI as the measure of ability. We conclude that the evidence for gender bias in the FCI questions is marginal at best.
Energy Technology Data Exchange (ETDEWEB)
Makhnovskii, Yurii A. [Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Leninsky Prospect 29, Moscow 119991 (Russian Federation); Berezhkovskii, Alexander M. [Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20819 (United States); Antipov, Anatoly E. [Faculty of Fundamental Physics and Chemical Engineering, Moscow State University, GSP-1, 1-51 Leninskie Gory, Moscow 119991 (Russian Federation); Zitserman, Vladimir Yu. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bldg. 2, Moscow 125412 (Russian Federation)
2015-11-07
This paper is devoted to particle transport in a tube formed by alternating wide and narrow sections, in the presence of an external biasing force. The focus is on the effective transport coefficients—mobility and diffusivity, as functions of the biasing force and the geometric parameters of the tube. Dependences of the effective mobility and diffusivity on the tube geometric parameters are known in the limiting cases of no bias and strong bias. The approximations used to obtain these results are inapplicable at intermediate values of the biasing force. To bridge the two limits Brownian dynamics simulations were run to determine the transport coefficients at intermediate values of the force. The simulations were performed for a representative set of tube geometries over a wide range of the biasing force. They revealed that there is a range of the narrow section length, where the force dependence of the mobility has a maximum. In contrast, the diffusivity is a monotonically increasing function of the force. A simple formula is proposed, which reduces to the known dependences of the diffusivity on the tube geometric parameters in both limits of zero and strong bias. At intermediate values of the biasing force, the formula catches the diffusivity dependence on the narrow section length, if the radius of these sections is not too small.
The estimation method of GPS instrumental biases
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A model of estimating the global positioning system (GPS) instrumental biases and the methods to calculate the relative instrumental biases of satellite and receiver are presented. The calculated results of GPS instrumental biases, the relative instrumental biases of satellite and receiver, and total electron content (TEC) are also shown. Finally, the stability of GPS instrumental biases as well as that of satellite and receiver instrumental biases are evaluated, indicating that they are very stable during a period of two months and a half.
Distributed force probe bending model of critical dimension atomic force microscopy bias
Ukraintsev, Vladimir A.; Orji, Ndubuisi G.; Vorburger, Theodore V.; Dixson, Ronald G.; Fu, Joseph; Silver, Rick M.
2013-04-01
Critical dimension atomic force microscopy (CD-AFM) is a widely used reference metrology technique. To characterize modern semiconductor devices, small and flexible probes, often 15 to 20 nm in diameter, are used. Recent studies have reported uncontrolled and significant probe-to-probe bias variation during linewidth and sidewall angle measurements. To understand the source of these variations, tip-sample interactions between high aspect ratio features and small flexible probes, and their influence on measurement bias, should be carefully studied. Using theoretical and experimental procedures, one-dimensional (1-D) and two-dimensional (2-D) models of cylindrical probe bending relevant to carbon nanotube (CNT) AFM probes were developed and tested. An earlier 1-D bending model was refined, and a new 2-D distributed force (DF) model was developed. Contributions from several factors were considered, including: probe misalignment, CNT tip apex diameter variation, probe bending before snapping, and distributed van der Waals-London force. A method for extracting Hamaker probe-surface interaction energy from experimental probe-bending data was developed. Comparison of the new 2-D model with 1-D single point force (SPF) model revealed a difference of about 28% in probe bending. A simple linear relation between biases predicted by the 1-D SPF and 2-D DF models was found. The results suggest that probe bending can be on the order of several nanometers and can partially explain the observed CD-AFM probe-to-probe variation. New 2-D and three-dimensional CD-AFM data analysis software is needed to take full advantage of the new bias correction modeling capabilities.
Self-Biased-SMA Drive PU Microgripper with Force Sensing in Visual Servo
Ren-Jung Chang; Chih-Cheng Shiu; Chih-Yi Cheng
2013-01-01
An innovative design of a polyurethane microgripper system with force sensor is developed for the measurement of gripping force in vision-based control. A microgripper mechanism integrated with a force sensing arm is fabricated by an excimer laser. The microgripper is actuated by a self-biased-SMA (Shape Memory Alloy) actuator. A computer-vision method through the ERES (Extended Regional Edge Statistics) algorithm is employed to track the motion of gripper. The position information of the gri...
Using forced choice to test belief bias in syllogistic reasoning.
Trippas, Dries; Verde, Michael F; Handley, Simon J
2014-12-01
In deductive reasoning, believable conclusions are more likely to be accepted regardless of their validity. Although many theories argue that this belief bias reflects a change in the quality of reasoning, distinguishing qualitative changes from simple response biases can be difficult (Dube, Rotello, & Heit, 2010). We introduced a novel procedure that controls for response bias. In Experiments 1 and 2, the task required judging which of two simultaneously presented syllogisms was valid. Surprisingly, there was no evidence for belief bias with this forced choice procedure. In Experiment 3, the procedure was modified so that only one set of premises was viewable at a time. An effect of beliefs emerged: unbelievable conclusions were judged more accurately, supporting the claim that beliefs affect the quality of reasoning. Experiments 4 and 5 replicated and extended this finding, showing that the effect was mediated by individual differences in cognitive ability and analytic cognitive style. Although the positive findings of Experiments 3-5 are most relevant to the debate about the mechanisms underlying belief bias, the null findings of Experiments 1 and 2 offer insight into how the presentation of an argument influences the manner in which people reason. PMID:25218460
Forecast Bias Correction: A Second Order Method
Crowell, Sean
2010-01-01
The difference between a model forecast and actual observations is called forecast bias. This bias is due to either incomplete model assumptions and/or poorly known parameter values and initial/boundary conditions. In this paper we discuss a method for estimating corrections to parameters and initial conditions that would account for the forecast bias. A set of simple experiments with the logistic ordinary differential equation is performed using an iterative version of a first order version of our method to compare with the second order version of the method.
Codon Usage Bias and Determining Forces in Taenia solium Genome.
Yang, Xing; Ma, Xusheng; Luo, Xuenong; Ling, Houjun; Zhang, Xichen; Cai, Xuepeng
2015-12-01
The tapeworm Taenia solium is an important human zoonotic parasite that causes great economic loss and also endangers public health. At present, an effective vaccine that will prevent infection and chemotherapy without any side effect remains to be developed. In this study, codon usage patterns in the T. solium genome were examined through 8,484 protein-coding genes. Neutrality analysis showed that T. solium had a narrow GC distribution, and a significant correlation was observed between GC12 and GC3. Examination of an NC (ENC vs GC3s)-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENC (the effective number of codons) values were detected below the expected curve, suggesting that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally. We also identified 26 optimal codons in the T. solium genome, all of which ended with either a G or C residue. These optimal codons in the T. solium genome are likely consistent with tRNAs that are highly expressed in the cell, suggesting that mutational and translational selection forces are probably driving factors of codon usage bias in the T. solium genome. PMID:26797435
A new polarization amplitude bias reduction method
Vidal, Matias; Leahy, J. P.; Dickinson, C.
2016-09-01
Polarization amplitude estimation is affected by a positive noise bias, particularly important in regions with low signal-to-noise ratio (SNR). We present a new approach to correct for this bias in the case there is additional information about the polarization angle. We develop the `known-angle estimator' that works in the special case when there is an independent and high SNR (≳ 2σ) measurement of the polarization angle. It is derived for the general case where the uncertainties in the Q, U Stokes parameters are not symmetric. This estimator completely corrects for the polarization bias if the polarization angle is perfectly known. In the realistic case, where the angle template has uncertainties, a small residual bias remains, but that is shown to be much smaller that the one left by other classical estimators. We also test our method with more realistic data, using the noise properties of the three lower frequency maps of Wilkinson Microwave Anisotropy Probe. In this case, the known-angle estimator also produces better results than methods that do not include the angle information. This estimator is therefore useful in the case where the polarization angle is expected to be constant over different data sets with different SNR.
A new method to measure galaxy bias
Pollack, Jennifer E; Porciani, Cristiano
2013-01-01
We present a new approach for modelling halo bias that utilizes the full non-linear information contained in the moments of the matter density field. The basis of our technique is to derive this information directly from a set of numerical simulations. Although our method is general, we perform a case study based on the local Eulerian bias scheme truncated to second-order. Using 200 N-body simulations that cover a total comoving volume of 675 (Gpc/h)^3, we measure several 2- and 3-point statistics of the halo distribution to unprecedented accuracy. We then use the bias model to fit the halo-halo power spectrum, the halo-matter cross spectrum and the corresponding three bispectra for wavenumbers in the range 0.04 < k < 0.12 h Mpc^-1. While all fits accurately describe the data, we find that the constraints on the bias parameters obtained using the full non-linear information differ significantly from those derived using leading-order standard perturbation theory. Hence, neglecting the full non-linear inf...
Zero-Variance Zero-Bias Principle for Observables in quantum Monte Carlo: Application to Forces
Assaraf, R
2003-01-01
A simple and stable method for computing accurate expectation values of observable with Variational Monte Carlo (VMC) or Diffusion Monte Carlo (DMC) algorithms is presented. The basic idea consists in replacing the usual ``bare'' estimator associated with the observable by an improved or ``renormalized'' estimator. Using this estimator more accurate averages are obtained: Not only the statistical fluctuations are reduced but also the systematic error (bias) associated with the approximate VMC or (fixed-node) DMC probability densities. It is shown that improved estimators obey a Zero-Variance Zero-Bias (ZVZB) property similar to the usual Zero-Variance Zero-Bias property of the energy with the local energy as improved estimator. Using this property improved estimators can be optimized and the resulting accuracy on expectation values may reach the remarkable accuracy obtained for total energies. As an important example, we present the application of our formalism to the computation of forces in molecular system...
Optimization of a parity of brake forces of automobiles in view of a bias of road
International Nuclear Information System (INIS)
In clause it is shown a method optimization of brake of forces in view of a bias road it is established, that in mountain conditions of loss of coupling weight of automobiles than 2-3 times concerning flat conditions therma are more. The degree of use of coupling weight in result use of a regulator of brake forces very much increases also efficiency of brake systems such a kind of automobiles is provided with definition of optimum factor of coupling at which value of loss of coupling weight is provided minimal
Self-Biased-SMA Drive PU Microgripper with Force Sensing in Visual Servo
Directory of Open Access Journals (Sweden)
Ren-Jung Chang
2013-06-01
Full Text Available An innovative design of a polyurethane microgripper system with force sensor is developed for the measurement of gripping force in vision-based control. A microgripper mechanism integrated with a force sensing arm is fabricated by an excimer laser. The microgripper is actuated by a self-biased-SMA (Shape Memory Alloy actuator. A computer-vision method through the ERES (Extended Regional Edge Statistics algorithm is employed to track the motion of gripper. The position information of the gripping point together with the deflection of the force sensing arm is utilized for sensing force. A fuzzy expert with a PI controller in a visual servo is employed to test the performance of sensing the gripping force in grasping of 38μm diameter metal rod. In the performance test, the microgripper system provides a maximum gripping size of 40μm, a maximum force resolution of 1μN and a maximum gripping force of 58μN.
Current-Induced Forces and Hot Spots in Biased Nanojunctions
DEFF Research Database (Denmark)
Lu, Jing Tao; Christensen, Rasmus Bjerregaard; Wang, Jian-Sheng;
2015-01-01
We investigate theoretically the interplay of current-induced forces (CIFs), Joule heating, and heat transport inside a current-carrying nanoconductor. We find that the CIFs, due to the electron-phonon coherence, can control the spatial heat dissipation in the conductor. This yields a significant...
The Air Force Officer Qualifying Test: Validity, Fairness, and Bias. Technical Report
Hardison, Chaitra M.; Sims, Carra S.; Wong, Eunice C.
2010-01-01
The Air Force has long recognized the importance of selecting the most qualified officers possible. For more than 60 years, it has relied on the Air Force Officer Qualifying Test (AFOQT) as one measure of those qualifications. A variety of concerns have been raised about whether the AFOQT is biased, too expensive, or even valid for predicting…
Tunable atomic force microscopy bias lithography on electron beam induced carbonaceous platforms
Directory of Open Access Journals (Sweden)
Narendra Kurra
2013-09-01
Full Text Available Tunable local electrochemical and physical modifications on the carbonaceous platforms are achieved using Atomic force microscope (AFM bias lithography. These carbonaceous platforms are produced on Si substrate by the technique called electron beam induced carbonaceous deposition (EBICD. EBICD is composed of functionalized carbon species, confirmed through X-ray photoelectron spectroscopy (XPS analysis. AFM bias lithography in tapping mode with a positive tip bias resulted in the nucleation of attoliter water on the EBICD surface under moderate humidity conditions (45%. While the lithography in the contact mode with a negative tip bias caused the electrochemical modifications such as anodic oxidation and etching of the EBICD under moderate (45% and higher (60% humidity conditions respectively. Finally, reversible charge patterns are created on these EBICD surfaces under low (30% humidity conditions and investigated by means of electrostatic force microscopy (EFM.
Restoring force method and response estimation
International Nuclear Information System (INIS)
The restoring force method is briefly outlined. Signal modifications that are necessary to successfully determine restoring force functions are discussed and illustrated. Restoring force functions for a base and a force excited system were determined and their effectiveness demonstrated by comparing measured and predicted signals. Additional developments that would make the restoring force method more general are suggested. 5 refs., 12 figs
Application of biasing techniques to the contributon Monte Carlo method
International Nuclear Information System (INIS)
Recently, a new Monte Carlo Method called the Contribution Monte Carlo Method was developed. The method is based on the theory of contributions, and uses a new receipe for estimating target responses by a volume integral over the contribution current. The analog features of the new method were discussed in previous publications. The application of some biasing methods to the new contribution scheme is examined here. A theoretical model is developed that enables an analytic prediction of the benefit to be expected when these biasing schemes are applied to both the contribution method and regular Monte Carlo. This model is verified by a variety of numerical experiments and is shown to yield satisfying results, especially for deep-penetration problems. Other considerations regarding the efficient use of the new method are also discussed, and remarks are made as to the application of other biasing methods. 14 figures, 1 tables
The shortwave radiative forcing bias of liquid and ice clouds from MODIS observations
Directory of Open Access Journals (Sweden)
L. Oreopoulos
2009-08-01
Full Text Available We present an assessment of the plane-parallel bias of the shortwave cloud radiative forcing (SWCRF of liquid and ice clouds at 1 deg scales using global MODIS (Terra and Aqua cloud optical property retrievals for four months of the year 2005 representative of the meteorological seasons. The (negative bias is estimated as the difference of SWCRF calculated using the Plane-Parallel Homogeneous (PPH approximation and the Independent Column Approximation (ICA. PPH calculations use MODIS-derived gridpoint means while ICA calculations use distributions of cloud optical thickness and effective radius. Assisted by a broadband solar radiative transfer algorithm, we find that the absolute value of global SWCRF bias of liquid clouds at the top of the atmosphere is about 6 W m^{−2} for MODIS overpass times while the SWCRF bias for ice clouds is smaller in absolute terms by about 0.7 W m^{−2}, but with stronger spatial variability. If effective radius variability is neglected and only optical thickness horizontal variations are accounted for, the absolute SWCRF biases increase by about 0.3–0.4 W m^{−2} on average. Marine clouds of both phases exhibit greater (more negative SWCRF biases than continental clouds. Finally, morning (Terra–afternoon (Aqua differences in SWCRF bias are much more pronounced for ice clouds, up to about 15% (Aqua producing stronger negative bias on global scales, with virtually all contribution to the difference coming from land areas. The substantial magnitude of the global SWCRF bias, which for clouds of both phases is collectively about 4 W m^{−2} for diurnal averages, should be considered a strong motivation for global climate modelers to accelerate efforts linking cloud schemes capable of subgrid condensate variability with appropriate radiative transfer schemes.
CEO emotional bias and dividend policy: Bayesian network method
Directory of Open Access Journals (Sweden)
Azouzi Mohamed Ali
2012-10-01
Full Text Available This paper assumes that managers, investors, or both behave irrationally. In addition, even though scholars have investigated behavioral irrationality from three angles, investor sentiment, investor biases and managerial biases, we focus on the relationship between one of the managerial biases, overconfidence and dividend policy. Previous research investigating the relationship between overconfidence and financial decisions has studied investment, financing decisions and firm values. However, there are only a few exceptions to examine how a managerial emotional bias (optimism, loss aversion and overconfidence affects dividend policies. This stream of research contends whether to distribute dividends or not depends on how managers perceive of the company’s future. I will use Bayesian network method to examine this relation. Emotional bias has been measured by means of a questionnaire comprising several items. As for the selected sample, it has been composed of some100 Tunisian executives. Our results have revealed that leader affected by behavioral biases (optimism, loss aversion, and overconfidence adjusts its dividend policy choices based on their ability to assess alternatives (optimism and overconfidence and risk perception (loss aversion to create of shareholder value and ensure its place at the head of the management team.
Bias-correction of CORDEX-MENA projections using the Distribution Based Scaling method
Bosshard, Thomas; Yang, Wei; Sjökvist, Elin; Arheimer, Berit; Graham, L. Phil
2014-05-01
Within the Regional Initiative for the Assessment of the Impact of Climate Change on Water Resources and Socio-Economic Vulnerability in the Arab Region (RICCAR) lead by UN ESCWA, CORDEX RCM projections for the Middle East Northern Africa (MENA) domain are used to drive hydrological impacts models. Bias-correction of newly available CORDEX-MENA projections is a central part of this project. In this study, the distribution based scaling (DBS) method has been applied to 6 regional climate model projections driven by 2 RCP emission scenarios. The DBS method uses a quantile mapping approach and features a conditional temperature correction dependent on the wet/dry state in the climate model data. The CORDEX-MENA domain is particularly challenging for bias-correction as it spans very diverse climates showing pronounced dry and wet seasons. Results show that the regional climate models simulate too low temperatures and often have a displaced rainfall band compared to WATCH ERA-Interim forcing data in the reference period 1979-2008. DBS is able to correct the temperature biases as well as some aspects of the precipitation biases. Special focus is given to the analysis of the influence of the dry-frequency bias (i.e. climate models simulating too few rain days) on the bias-corrected projections and on the modification of the climate change signal by the DBS method.
Dynamic atomic force microscopy methods
García, Ricardo; Pérez, Rubén
2002-09-01
In this report we review the fundamentals, applications and future tendencies of dynamic atomic force microscopy (AFM) methods. Our focus is on understanding why the changes observed in the dynamic properties of a vibrating tip that interacts with a surface make possible to obtain molecular resolution images of membrane proteins in aqueous solutions or to resolve atomic-scale surface defects in ultra high vacuum (UHV). Our description of the two major dynamic AFM modes, amplitude modulation atomic force microscopy (AM-AFM) and frequency modulation atomic force microscopy (FM-AFM) emphasises their common points without ignoring the differences in experimental set-ups and operating conditions. Those differences are introduced by the different feedback parameters, oscillation amplitude in AM-AFM and frequency shift and excitation amplitude in FM-AFM, used to track the topography and composition of a surface. The theoretical analysis of AM-AFM (also known as tapping-mode) emphasises the coexistence, in many situations of interests, of two stable oscillation states, a low and high amplitude solution. The coexistence of those oscillation states is a consequence of the presence of attractive and repulsive components in the interaction force and their non-linear dependence on the tip-surface separation. We show that key relevant experimental properties such as the lateral resolution, image contrast and sample deformation are highly dependent on the oscillation state chosen to operate the instrument. AM-AFM allows to obtain simultaneous topographic and compositional contrast in heterogeneous samples by recording the phase angle difference between the external excitation and the tip motion (phase imaging). Significant applications of AM-AFM such as high-resolution imaging of biomolecules and polymers, large-scale patterning of silicon surfaces, manipulation of single nanoparticles or the fabrication of single electron devices are also reviewed. FM-AFM (also called non
Reduction of systematic biases in regional climate downscaling through ensemble forcing
Energy Technology Data Exchange (ETDEWEB)
Yang, Hongwei; Wang, Bin [Chinese Academy of Sciences, LASG, Institute of Atmospheric Physics, Beijing (China); Wang, Bin [University of Hawaii at Manoa, Department of Meteorology, Honolulu, Hawaii (United States); University of Hawaii at Manoa, International Pacific Research Center, Honolulu, Hawaii (United States)
2012-02-15
Simulations of the East Asian summer monsoon for the period of 1979-2001 were carried out using the Weather Research and Forecast (WRF) model forced by three reanalysis datasets (NCEP-R2, ERA-40, and JRA-25). The experiments forced by different reanalysis data exhibited remarkable differences, primarily caused by uncertainties in the lateral boundary (LB) moisture fluxes over the Bay of Bengal and the Philippine Sea. The climatological mean water vapor convergence into the model domain computed from ERA-40 was about 24% higher than that from the NCEP-R2 reanalysis. We demonstrate that using the ensemble mean of NCEP-R2, ERA-40, and JRA-25 as LB forcing considerably reduced the biases in the model simulation. The use of ensemble forcing improved the performance in simulated mean circulation and precipitation, inter-annual variation in seasonal precipitation, and daily precipitation. The model simulated precipitation was superior to that in the reanalysis in both climatology and year-to-year variations, indicating the added value of dynamic downscaling. The results suggest that models having better performance under one set of LB forcing might worsen when another set of reanalysis data is used as LB forcing. Use of ensemble mean LB forcing for assessing regional climate model performance is recommended. (orig.)
CEO emotional bias and investment decision, Bayesian network method
Directory of Open Access Journals (Sweden)
Jarboui Anis
2012-08-01
Full Text Available This research examines the determinants of firms’ investment introducing a behavioral perspective that has received little attention in corporate finance literature. The following central hypothesis emerges from a set of recently developed theories: Investment decisions are influenced not only by their fundamentals but also depend on some other factors. One factor is the biasness of any CEO to their investment, biasness depends on the cognition and emotions, because some leaders use them as heuristic for the investment decision instead of fundamentals. This paper shows how CEO emotional bias (optimism, loss aversion and overconfidence affects the investment decisions. The proposed model of this paper uses Bayesian Network Method to examine this relationship. Emotional bias has been measured by means of a questionnaire comprising several items. As for the selected sample, it has been composed of some 100 Tunisian executives. Our results have revealed that the behavioral analysis of investment decision implies leader affected by behavioral biases (optimism, loss aversion, and overconfidence adjusts its investment choices based on their ability to assess alternatives (optimism and overconfidence and risk perception (loss aversion to create of shareholder value and ensure its place at the head of the management team.
FORC analysis of ferro-ferromagnetic exchange bias in nanocrystalline ribbons
Martínez-García, J. C.; Rivas, M.; García, J. A.
2016-04-01
Horizontal shift and distortion of the hysteresis loops can be induced in some Co-based nanocrystalline systems in which soft and hard ferromagnetic phases coexist. As all the aspects of the phenomenon can be well explained in terms of the exchange interaction between the two phases, it has been identified as an induced ferro-ferromagnetic exchange bias. In this work we use the differential analysis based on first-order reversal curves to analyse this particular kind of exchange bias, through the comparison of the FORC diagrams corresponding to samples with different crystallization degrees. A detailed study of the evolution of such diagrams is presented, pointing in each case to the more outstanding features of the spots corresponding to the different phases as well as to their interactions.
Tip-bias-induced domain evolution in PMN-PT transparent ceramics via piezoresponse force microscopy
Zhao, K. Y.; Zhao, W.; Zeng, H. R.; Yu, H. Z.; Ruan, W.; Xu, K. Q.; Li, G. R.
2015-05-01
Piezoresponse force microscopy (PFM) was employed to investigate ferroelectric domain structures and their dynamic behavior of lead magnesium niobate-lead titanate [Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT)] transparent ceramics under an tip-bias-induced electric field. A remarkable effect of fluctuation of PT content on the domain configurations and domain dynamic response in PMN-PT transparent ferroelectric ceramics were found by PFM. Comparing with PMN-10%PT and PMN-20%PT, the reversed polarization of macrodomain area in PMN-35%PT and PMN-25%PT exhibits a relatively higher response behavior and better polarization retention performance under the PFM tip-bias-induced electric field, which correspond to their unique macroscopic electro-optic properties.
On the bias of yield-based capital budgeting methods
Olivier Rousse
2008-01-01
The aim of this paper is twofold. First, we present a new capital budgeting method, called the real rate of return (RRR), which has been developed for solving the inconsistency of the modified internal rate of return (MIRR) with shareholders' wealth maximization when costs of capital differ between projects. After surveying the merits of this method over the MIRR, we focus our attention on another interesting feature of the RRR when cash flows are uncertain. We compare the RRR bias with the M...
Energy Technology Data Exchange (ETDEWEB)
Garcia, M.M.; Jimenez, I.; Vazquez, L.; Gomez-Aleixandre, C.; Albella, J.M.; Sanchez, O. [Instituto de Ciencia de Materiales, C.S.I.C., Cantoblanco28049, Madrid (Spain); Terminello, L.J. [Lawrence Livermore National Laboratory, Livermore, California94551 (United States); Himpsel, F.J. [Department of Physics, University of Wisconsin--Madison, Madison, Wisconsin53706 (United States)
1998-04-01
The bias-enhanced nucleation of diamond on Si(100) has been studied by x-ray absorption near-edge spectroscopy (XANES) and atomic force microscopy, two techniques well suited to characterize nanometric crystallites. Diamond nuclei of {approximately}15nm are formed after 5 min of bias-enhanced treatment. The number of nuclei and its size increases with the time of application of the bias voltage. A nanocrystalline diamond film is attained after 20 min of bias-enhanced nucleation. At the initial nucleation stages, the Si substrate appears covered with diamond crystallites and graphite, without SiC being detected by XANES. {copyright} {ital 1998 American Institute of Physics.}
Information bias in health research: definition, pitfalls, and adjustment methods
Althubaiti, Alaa
2016-01-01
As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassification, is one of the most common sources of bias that affects the validity of health research. It originates from the approach that is utilized to obtain or confir...
Nonlinear structural analysis using integrated force method
Indian Academy of Sciences (India)
N R B Krishnam Raju; J Nagabhushanam
2000-08-01
Though the use of the integrated force method for linear investigations is well-recognised, no efforts were made to extend this method to nonlinear structural analysis. This paper presents the attempts to use this method for analysing nonlinear structures. General formulation of nonlinear structural analysis is given. Typically highly nonlinear bench-mark problems are considered. The characteristic matrices of the elements used in these problems are developed and later these structures are analysed. The results of the analysis are compared with the results of the displacement method. It has been demonstrated that the integrated force method is equally viable and efficient as compared to the displacement method.
Directory of Open Access Journals (Sweden)
J.-K. Lee
2015-11-01
Full Text Available There are many potential sources of the biases in the radar rainfall estimation process. This study classified the biases from the rainfall estimation process into the reflectivity measurement bias and the rainfall estimation bias by the Quantitative Precipitation Estimation (QPE model and also conducted the bias correction methods to improve the accuracy of the Radar-AWS Rainrate (RAR calculation system operated by the Korea Meteorological Administration (KMA. In the Z bias correction for the reflectivity biases occurred by measuring the rainfalls, this study utilized the bias correction algorithm. The concept of this algorithm is that the reflectivity of the target single-pol radars is corrected based on the reference dual-pol radar corrected in the hardware and software bias. This study, and then, dealt with two post-process methods, the Mean Field Bias Correction (MFBC method and the Local Gauge Correction method (LGC, to correct the rainfall estimation bias by the QPE model. The Z bias and rainfall estimation bias correction methods were applied to the RAR system. The accuracy of the RAR system was improved after correcting Z bias. For the rainfall types, although the accuracy of the Changma front and the local torrential cases was slightly improved without the Z bias correction the accuracy of the typhoon cases got worse than the existing results in particular. As a result of the rainfall estimation bias correction, the Z bias_LGC was especially superior to the MFBC method because the different rainfall biases were applied to each grid rainfall amount in the LGC method. For the rainfall types, the results of the Z bias_LGC showed that the rainfall estimates for all types was more accurate than only the Z bias and, especially, the outcomes in the typhoon cases was vastly superior to the others.
Spherical collapse in Galileon gravity: fifth force solutions, halo mass function and halo bias
International Nuclear Information System (INIS)
We study spherical collapse in the Quartic and Quintic Covariant Galileon gravity models within the framework of the excursion set formalism. We derive the nonlinear spherically symmetric equations in the quasi-static and weak-field limits, focusing on model parameters that fit current CMB, SNIa and BAO data. We demonstrate that the equations of the Quintic model do not admit physical solutions of the fifth force in high density regions, which prevents the study of structure formation in this model. For the Quartic model, we show that the effective gravitational strength deviates from the standard value at late times (z∼<1), becoming larger if the density is low, but smaller if the density is high. This shows that the Vainshtein mechanism at high densities is not enough to screen all of the modifications of gravity. This makes halos that collapse at z∼<1 feel an overall weaker gravity, which suppresses halo formation. However, the matter density in the Quartic model is higher than in standard ΛCDM, which boosts structure formation and dominates over the effect of the weaker gravity. In the Quartic model there is a significant overabundance of high-mass halos relative to ΛCDM. Dark matter halos are also less biased than in ΛCDM, with the difference increasing appreciably with halo mass. However, our results suggest that the bias may not be small enough to fully reconcile the predicted matter power spectrum with LRG clustering data
Sample preparation method for scanning force microscopy
Jankov, I R; Szente, R N; Carreno, M N P; Swart, J W; Landers, R
2001-01-01
We present a method of sample preparation for studies of ion implantation on metal surfaces. The method, employing a mechanical mask, is specially adapted for samples analysed by Scanning Force Microscopy. It was successfully tested on polycrystalline copper substrates implanted with phosphorus ions at an acceleration voltage of 39 keV. The changes of the electrical properties of the surface were measured by Kelvin Probe Force Microscopy and the surface composition was analysed by Auger Electron Spectroscopy.
Bias annealing: A method for obtaining transition paths de novo
Hu, Jie; Ma, Ao; Dinner, Aaron R.
2006-09-01
Computational studies of dynamics in complex systems require means for generating reactive trajectories with minimum knowledge about the processes of interest. Here, we introduce a method for generating transition paths when an existing one is not already available. Starting from biased paths obtained from steered molecular dynamics, we use a Monte Carlo procedure in the space of whole trajectories to shift gradually to sampling an ensemble of unbiased paths. Application to basin-to-basin hopping in a two-dimensional model system and nucleotide-flipping by a DNA repair protein demonstrates that the method can efficiently yield unbiased reactive trajectories even when the initial steered dynamics differ significantly. The relation of the method to others and the physical basis for its success are discussed.
Directory of Open Access Journals (Sweden)
J.-K. Lee
2015-04-01
Full Text Available There are many potential sources of bias in the radar rainfall estimation process. This study classified the biases from the rainfall estimation process into the reflectivity measurement bias and QPE model bias and also conducted the bias correction methods to improve the accuracy of the Radar-AWS Rainrate (RAR calculation system operated by the Korea Meteorological Administration (KMA. For the Z bias correction, this study utilized the bias correction algorithm for the reflectivity. The concept of this algorithm is that the reflectivity of target single-pol radars is corrected based on the reference dual-pol radar corrected in the hardware and software bias. This study, and then, dealt with two post-process methods, the Mean Field Bias Correction (MFBC method and the Local Gauge Correction method (LGC, to correct rainfall-bias. The Z bias and rainfall-bias correction methods were applied to the RAR system. The accuracy of the RAR system improved after correcting Z bias. For rainfall types, although the accuracy of Changma front and local torrential cases was slightly improved without the Z bias correction, especially, the accuracy of typhoon cases got worse than existing results. As a result of the rainfall-bias correction, the accuracy of the RAR system performed Z bias_LGC was especially superior to the MFBC method because the different rainfall biases were applied to each grid rainfall amount in the LGC method. For rainfall types, Results of the Z bias_LGC showed that rainfall estimates for all types was more accurate than only the Z bias and, especially, outcomes in typhoon cases was vastly superior to the others.
Information bias in health research: definition, pitfalls, and adjustment methods
Althubaiti A
2016-01-01
Alaa Althubaiti Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia Abstract: As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassific...
CEO emotional bias and dividend policy: Bayesian network method
Azouzi Mohamed Ali; Jarboui Anis
2012-01-01
This paper assumes that managers, investors, or both behave irrationally. In addition, even though scholars have investigated behavioral irrationality from three angles, investor sentiment, investor biases and managerial biases, we focus on the relationship between one of the managerial biases, overconfidence and dividend policy. Previous research investigating the relationship between overconfidence and financial decisions has studied investment, financing decisions and firm values. However,...
Biases of tree-independent-character-subsampling methods.
Simmons, Mark P; Gatesy, John
2016-07-01
Observed Variability (OV) and Tree Independent Generation of Evolutionary Rates (TIGER) are quick and easy-to-apply tree-independent methods that have been proposed to provide unbiased estimates of each character's rate of evolution and serve as the basis for excluding rapidly evolving characters. Both methods have been applied to multiple phylogenomic datasets, and in many cases the authors considered their trees inferred from the OV- and TIGER-delimited sub-matrices to be better estimates of the phylogeny than their trees based on all characters. In this study we use four sets of simulations and an empirical phylogenomic example to demonstrate that both methods share a systematic bias against characters with more symmetric distributions of character states, against characters with greater observed character-state space, and against large clades in the context of character conflict. As a result these methods can favor convergences and reversals over synapomorphy, exacerbate long-branch attraction, and produce mutually exclusive phylogenetic inferences that are dependent upon differential taxon sampling. We assert that neither OV nor TIGER should be relied upon to increase the ratio of phylogenetic to non-phylogenetic signal in a data matrix. We also assert that skepticism is warranted for empirical phylogenetic results that are based on OV- and/or TIGER-based character deletion wherein a small clade is supported after deletion of characters, yet is contradicted by a larger clade when the entire data matrix was analyzed. PMID:27103257
A Polynomial Prediction Filter Method for Estimating Multisensor Dynamically Varying Biases
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The estimation of the sensor measurement biases in a multisensor system is vital for the sensor data fusion. A solution is provided for the estimation of dynamically varying multiple sensor biases without any knowledge of the dynamic bias model parameters. It is shown that the sensor bias pseudomeasurement can be dynamically obtained via a parity vector. This is accomplished by multiplying the sensor uncalibrated measurement equations by a projection matrix so that the measured variable is eliminated from the equations. Once the state equations of the dynamically varying sensor biases are modeled by a polynomial prediction filter, the dynamically varying multisensor biases can be obtained by Kalman filter. Simulation results validate that the proposed method can estimate the constant biases and dynamic biases of multisensors and outperforms the methods reported in literature.
Computing Method of Forces on Rivet
Directory of Open Access Journals (Sweden)
Ion DIMA
2014-03-01
Full Text Available This article aims to provide a quick methodology of forces calculation on rivet in single shear using the finite element method (FEM – NASTRAN/PATRAN. These forces can be used for the calculus of bearing, inter rivet buckling and riveting check. For this method to be efficient and fast, a macro has been developed based on this methodology described in the article. The macro was wrote in Visual Basic with Excel interface. In the beginning phase of any aircraft project, when the rivets type and position are not yet precisely known, the modelling of rivets, as attachment elements between items, is made node on node in the finite element model, without taking account of the rivets position. Although the rivets are not modelled in the finite element model, this method together with the macro enable a quick extraction and calculation of the forces on the rivet. This calculation of forces on rivet is intended to critical case, selected from the stress plots of NASTRAN for max. /min. principal stress and shear.
CEO emotional bias and investment decision, Bayesian network method
Jarboui Anis; Mohamed Ali Azouzi
2012-01-01
This research examines the determinants of firms’ investment introducing a behavioral perspective that has received little attention in corporate finance literature. The following central hypothesis emerges from a set of recently developed theories: Investment decisions are influenced not only by their fundamentals but also depend on some other factors. One factor is the biasness of any CEO to their investment, biasness depends on the cognition and emotions, because some leaders use them as h...
Evaluating a Combined Bias Correction and Stochastic Downscaling Method
Volosciuk, Claudia; Maraun, Douglas; Vrac, Mathieu; Widmann, Martin
2016-04-01
Much of our knowledge about future changes in precipitation relies on global (GCM) and/or regional climate models (RCM) that have resolutions which are much coarser than typical spatial scales of extreme precipitation. The major problems with these projections are both climate model biases and the scale gap between grid box and point scale. Wong et al. presented a first attempt to jointly bias correct and downscale precipitation at daily scales. This approach however relied on spectrally nudged RCM simulations and was not able to post-process GCM biases. Previously, we have presented an extension of this approach that separates the downscaling from the bias correction and in principle is applicable to free running RCMs, such as those available from ENSEMBLES or CORDEX. In a first step, we bias correct the RCMs (EURO-CORDEX) against gridded observational datasets (e.g., E-OBS) at the same scale using a quantile mapping approach that relies on distribution transformation. To correct the whole precipitation distribution including extreme tails we apply a mixture distribution of a gamma distribution for the precipitation mass and a generalized Pareto distribution for the extreme tail. In a second step, we bridge the scale gap: we add small scale variability to the bias corrected precipitation time series using a vector generalized linear gamma model (VGLM gamma). To calibrate the VGLM gamma model we determine the statistical relationship between precipitation observations on different scales, i.e. between gridded (e.g., E-OBS) and station (ECA&D) observations. Here we present a comprehensive evaluation of this approach against 86 weather stations in Europe based on the VALUE perfect predictor experiment, including a comparison with standard bias correction techniques.
Correcting for Partial Verification Bias: A Comparison of Methods
J.A.H. de Groot; K.J.M. Janssen; A.H. Zwinderman; P.M.M. Bossuyt; J.B. Reitsma; K.G.M. Moons
2011-01-01
PURPOSE: A common problem in diagnostic research is that the reference standard has not been carried out in all patients. This partial verification may lead to biased accuracy measures of the test under study. The authors studied the performance of multiple imputation and the conventional correction
Samozino, P; Rabita, G; Dorel, S; Slawinski, J; Peyrot, N; Saez de Villarreal, E; Morin, J-B
2016-06-01
This study aimed to validate a simple field method for determining force- and power-velocity relationships and mechanical effectiveness of force application during sprint running. The proposed method, based on an inverse dynamic approach applied to the body center of mass, estimates the step-averaged ground reaction forces in runner's sagittal plane of motion during overground sprint acceleration from only anthropometric and spatiotemporal data. Force- and power-velocity relationships, the associated variables, and mechanical effectiveness were determined (a) on nine sprinters using both the proposed method and force plate measurements and (b) on six other sprinters using the proposed method during several consecutive trials to assess the inter-trial reliability. The low bias (running. PMID:25996964
N3 Bias Field Correction Explained as a Bayesian Modeling Method
DEFF Research Database (Denmark)
Larsen, Christian Thode; Iglesias, Juan Eugenio; Van Leemput, Koen
2014-01-01
this paper we explain the successful bias field correction properties of N3 by showing that it implicitly uses the same generative models and computational strategies as expectation maximization (EM) based bias field correction methods. We demonstrate experimentally that purely EM-based methods are...
Method for removing atomic-model bias in macromolecular crystallography
Terwilliger, Thomas C.
2006-08-01
Structure factor bias in an electron density map for an unknown crystallographic structure is minimized by using information in a first electron density map to elicit expected structure factor information. Observed structure factor amplitudes are combined with a starting set of crystallographic phases to form a first set of structure factors. A first electron density map is then derived and features of the first electron density map are identified to obtain expected distributions of electron density. Crystallographic phase probability distributions are established for possible crystallographic phases of reflection k, and the process is repeated as k is indexed through all of the plurality of reflections. An updated electron density map is derived from the crystallographic phase probability distributions for each one of the reflections. The entire process is then iterated to obtain a final set of crystallographic phases with minimum bias from known electron density maps.
Methods of Monte Carlo biasing using two-dimensional discrete ordinates adjoint flux
Energy Technology Data Exchange (ETDEWEB)
Tang, J.S.; Stevens, P.N.; Hoffman, T.J.
1976-06-01
Methods of biasing three-dimensional deep penetration Monte Carlo calculations using importance functions obtained from a two-dimensional discrete ordinates adjoint calculation have been developed. The important distinction was made between the applications of the point value and the event value to alter the random walk in Monte Carlo analysis of radiation transport. The biasing techniques developed are the angular probability biasing which alters the collision kernel using the point value as the importance function and the path length biasing which alters the transport kernel using the event value as the importance function. Source location biasings using the step importance function and the scalar adjoint flux obtained from the two-dimensional discrete ordinates adjoint calculation were also investigated. The effects of the biasing techniques to Monte Carlo calculations have been investigated for neutron transport through a thick concrete shield with a penetrating duct. Source location biasing, angular probability biasing, and path length biasing were employed individually and in various combinations. Results of the biased Monte Carlo calculations were compared with the standard Monte Carlo and discrete ordinates calculations.
DriftLess™, an innovative method to estimate and compensate for the biases of inertial sensors
Ruizenaar, M.G.H.; Kemp, R.A.W.
2014-01-01
In this paper a method is presented that allows for bias compensation of low-cost MEMS inertial sensors. It is based on the use of two sets of inertial sensors and a rotation mechanism that physically rotates the sensors in an alternating fashion. After signal processing, the biases of both sets of
Variance bias analysis for the Gelbard's batch method
International Nuclear Information System (INIS)
In this paper, variances and the bias will be derived analytically when the Gelbard's batch method is applied. And then, the real variance estimated from this bias will be compared with the real variance calculated from replicas. Variance and the bias were derived analytically when the batch method was applied. If the batch method was applied to calculate the sample variance, covariance terms between tallies which exist in the batch were eliminated from the bias. With the 2 by 2 fission matrix problem, we could calculate real variance regardless of whether or not the batch method was applied. However as batch size got larger, standard deviation of real variance was increased. When we perform a Monte Carlo estimation, we could get a sample variance as the statistical uncertainty of it. However, this value is smaller than the real variance of it because a sample variance is biased. To reduce this bias, Gelbard devised the method which is called the Gelbard's batch method. It has been certificated that a sample variance get closer to the real variance when the batch method is applied. In other words, the bias get reduced. This fact is well known to everyone in the MC field. However, so far, no one has given the analytical interpretation on it
Extended force density method and its expressions
Miki, Masaaki
2011-01-01
The objective of this work can be divided into two parts. The first one is to propose an extension of the force density method (FDM)(H.J. Schek, 1974), a form-finding method for prestressed cable-net structures. The second one is to present a review of various form-finding methods for tension structures, in the relation with the extended FDM. In the first part, it is pointed out that the original FDM become useless when it is applied to the prestressed structures that consist of combinations of both tension and compression members, while the FDM is usually advantageous in form-finding analysis of cable-nets. To eliminate the limitation, a functional whose stationary problem simply represents the FDM is firstly proposed. Additionally, the existence of a variational principle in the FDM is also indicated. Then, the FDM is extensively redefined by generalizing the formulation of the functional. As the result, the generalized functionals enable us to find the forms of tension structures that consist of combinatio...
A Method for Estimating BeiDou Inter-frequency Satellite Clock Bias
Directory of Open Access Journals (Sweden)
LI Haojun
2016-02-01
Full Text Available A new method for estimating the BeiDou inter-frequency satellite clock bias is proposed, considering the shortage of the current methods. The constant and variable parts of the inter-frequency satellite clock bias are considered in the new method. The data from 10 observation stations are processed to validate the new method. The characterizations of the BeiDou inter-frequency satellite clock bias are also analyzed using the computed results. The results of the BeiDou inter-frequency satellite clock bias indicate that it is stable in the short term. The estimated BeiDou inter-frequency satellite clock bias results are molded. The model results show that the 10 parameters of model for each satellite can express the BeiDou inter-frequency satellite clock bias well and the accuracy reaches cm level. When the model parameters of the first day are used to compute the BeiDou inter-frequency satellite clock bias of the second day, the accuracy also reaches cm level. Based on the stability and modeling, a strategy for the BeiDou satellite clock service is presented to provide the reference of our BeiDou.
Optimal attitude determination method in presence of noise and bias on different star sensors
Directory of Open Access Journals (Sweden)
Amir Moghtadaei Rad
2014-03-01
Full Text Available There are different attitude determination methods which have been used in satellite and spacecraft by star tracker. Each of these methods have its own advantages and disadvantages depending on their application, stochastic characteristic of noise on sensors (bias or noise, and weight of noise falling on different sensors. The present study has thus explored the major methods from two perspectives: the effect of input noise or bias on each star sensor and the corresponding weight of each noise or bias falling on each sensor. These aspects are compared in each method and the optimal method according to each condition is introduced. N Vector, Triad, Quest, Q method and least square method are the methods studied and simulated in this article. Finally, a comparison is made between the methods and the optimal method is introduced theoretically and practically. Keywords: Attitude Determination, Celestial Navigation, Triad, Quest, Least Square, Satellite.
A scanning tunneling microscope break junction method with continuous bias modulation.
Beall, Edward; Yin, Xing; Waldeck, David H; Wierzbinski, Emil
2015-09-28
Single molecule conductance measurements on 1,8-octanedithiol were performed using the scanning tunneling microscope break junction method with an externally controlled modulation of the bias voltage. Application of an AC voltage is shown to improve the signal to noise ratio of low current (low conductance) measurements as compared to the DC bias method. The experimental results show that the current response of the molecule(s) trapped in the junction and the solvent media to the bias modulation can be qualitatively different. A model RC circuit which accommodates both the molecule and the solvent is proposed to analyze the data and extract a conductance for the molecule. PMID:26308622
Are shear force methods adequately reported?
Holman, Benjamin W B; Fowler, Stephanie M; Hopkins, David L
2016-09-01
This study aimed to determine the detail to which shear force (SF) protocols and methods have been reported in the scientific literature between 2009 and 2015. Articles (n=734) published in peer-reviewed animal and food science journals and limited to only those testing the SF of unprocessed and non-fabricated mammal meats were evaluated. It was found that most of these SF articles originated in Europe (35.3%), investigated bovine species (49.0%), measured m. longissimus samples (55.2%), used tenderometers manufactured by Instron (31.2%), and equipped with Warner-Bratzler blades (68.8%). SF samples were also predominantly thawed prior to cooking (37.1%) and cooked sous vide, using a water bath (50.5%). Information pertaining to blade crosshead speed (47.5%), recorded SF resistance (56.7%), muscle fibre orientation when tested (49.2%), sub-section or core dimension (21.8%), end-point temperature (29.3%), and other factors contributing to SF variation were often omitted. This base failure diminishes repeatability and accurate SF interpretation, and must therefore be rectified. PMID:27107727
Method for exploiting bias in factor analysis using constrained alternating least squares algorithms
Keenan, Michael R.
2008-12-30
Bias plays an important role in factor analysis and is often implicitly made use of, for example, to constrain solutions to factors that conform to physical reality. However, when components are collinear, a large range of solutions may exist that satisfy the basic constraints and fit the data equally well. In such cases, the introduction of mathematical bias through the application of constraints may select solutions that are less than optimal. The biased alternating least squares algorithm of the present invention can offset mathematical bias introduced by constraints in the standard alternating least squares analysis to achieve factor solutions that are most consistent with physical reality. In addition, these methods can be used to explicitly exploit bias to provide alternative views and provide additional insights into spectral data sets.
Comparison of Parametric and Nonparametric Methods for Analyzing the Bias of a Numerical Model
Directory of Open Access Journals (Sweden)
Isaac Mugume
2016-01-01
Full Text Available Numerical models are presently applied in many fields for simulation and prediction, operation, or research. The output from these models normally has both systematic and random errors. The study compared January 2015 temperature data for Uganda as simulated using the Weather Research and Forecast model with actual observed station temperature data to analyze the bias using parametric (the root mean square error (RMSE, the mean absolute error (MAE, mean error (ME, skewness, and the bias easy estimate (BES and nonparametric (the sign test, STM methods. The RMSE normally overestimates the error compared to MAE. The RMSE and MAE are not sensitive to direction of bias. The ME gives both direction and magnitude of bias but can be distorted by extreme values while the BES is insensitive to extreme values. The STM is robust for giving the direction of bias; it is not sensitive to extreme values but it does not give the magnitude of bias. The graphical tools (such as time series and cumulative curves show the performance of the model with time. It is recommended to integrate parametric and nonparametric methods along with graphical methods for a comprehensive analysis of bias of a numerical model.
Watanabe, Satoshi; Kanae, Shinjiro; Seto, Shinta; Yeh, Pat J.-F.; Hirabayashi, Yukiko; Oki, Taikan
2012-12-01
Bias-correction methods applied to monthly temperature and precipitation data simulated by multiple General Circulation Models (GCMs) are evaluated in this study. Although various methods have been proposed recently, an intercomparison among them using multiple GCM simulations has seldom been reported. Moreover, no previous methods have addressed the issue how to adequately deal with the changes of the statistics of bias-corrected variables from the historical to future simulations. In this study, a new method which conserves the changes of mean and standard deviation of the uncorrected model simulation data is proposed, and then five previous bias-correction methods as well as the proposed new method are intercompared by applying them to monthly temperature and precipitation data simulated from 12 GCMs in the Coupled Model Intercomparison Project (CMIP3) archives. Parameters of each method are calibrated by using 1948-1972 observed data and validated in the 1974-1998 period. These methods are then applied to the GCM future simulations (2073-2097) and the bias-corrected data are intercompared. For the historical simulations, negligible difference can be found between observed and bias-corrected data. However, the differences in future simulations are large dependent on the characteristics of each method. The new method successfully conserves the changes in the mean, standard deviation and the coefficient of variation before and after bias-correction. The differences of bias-corrected data among methods are discussed according to their respective characteristics. Importantly, this study classifies available correction methods into two distinct categories, and articulates important features for each of them.
Directory of Open Access Journals (Sweden)
W. Terink
2010-01-01
Full Text Available In many climate impact studies hydrological models are forced with meteorological data without an attempt to assess the quality of these data. The objective of this study is to compare downscaled ERA15 (ECMWF-reanalysis data precipitation and temperature with observed precipitation and temperature and apply a bias correction to these forcing variables. Precipitation is corrected by fitting the mean and coefficient of variation (CV of the observations. Temperature is corrected by fitting the mean and standard deviation of the observations. It appears that the uncorrected ERA15 is too warm and too wet for most of the Rhine basin. The bias correction leads to satisfactory results, precipitation and temperature differences decreased significantly, although there are a few years for which the correction of precipitation is less satisfying. Corrections were largest during summer for both precipitation and temperature, and for September and October for precipitation only. Besides the statistics the correction method was intended to correct for, it is also found to improve the correlations for the fraction of wet days and lag-1 autocorrelations between ERA15 and the observations. For the validation period temperature is corrected very well, but for precipitation the RMSE of the daily difference between modeled and observed precipitation has increased for the corrected situation. When taking random years for calibration, and the remaining years for validation, the spread in the mean bias error (MBE becomes larger for the corrected precipitation during validation, but the overal average MBE has decreased.
Novel Actuation Methods for High Force Haptics
Buerger, Stephen P.; Hogan, Neville
2010-01-01
This chapter presented and defined high force haptic systems, and articulated the specific constraints that make the selection of actuators for this application difficult. To provide context, the pioneering high force haptics application of therapeutic robotics, and the obstacles to continued advancement of the field, were discussed. We continue to develop therapeutic robots for human movement from lower body (including partial weight support) to fine finger motions, and the actuation problem...
Jou, Jerwen; Flores, Shaney; Cortes, Hector M; Leka, Bryce G
2016-06-01
It is widely believed that a Two-Alternative-Forced-Choice (2AFC) in an old/new recognition memory test is made by comparing the two items and choosing the item with the higher strength. For this reason, it is considered to be criterion-free by some researchers. We found evidence that subjects probabilistically compromised the comparison by choosing the left item when they recognized it as old. Using both normal test pairs (comprised of one new and one old item) and two types of null pairs (comprised of both-new or both-old items), we found that a left-biased choice was coupled with higher hit and false alarm rates and a shorter left than right-choice RT for the normal pairs, consistent with the hypothesis of a bias for making a choice on the basis of a left individual-item recognition. For the null pairs, RT was much longer for the both-new than for the both-old pairs, providing additional evidence for basing decision on an individual-item's absolute, rather than a relative, familiarity. Additionally, subjects gave higher confidence ratings to choices for the both-old than the normal and both-new pairs, again suggesting that their decision was based on absolute familiarity of the items. The results were found to be not due to a fast-response instruction. A comparative judgment experiment in which subjects chose the item higher or lower in an attribute magnitude did not show the response side bias and RT asymmetry. The presence of bias in the former, and the absence of it in the latter can be explained by a weak versus strong relational judgment in the former and the latter type of 2AFC, respectively. We discuss the implications these findings have for the use of the 2AFC as a method for testing recognition memory. PMID:27104925
Current-induced forces and hot-spots in biased nano-junctions
Lu, Jing Tao; Christensen, Rasmus Bjerregaard; Wang, Jian-Sheng; Hedegård, Per; Brandbyge, Mads
2014-01-01
We investigate theoretically the interplay of current-induced forces (CIFs), Joule heating, and heat transport inside a current-carrying nanoconductor. We find that the CIFs, due to the electron-phonon coherence, can control the spatial heat dissipation in the conductor. This yields a significant asymmetric concentration of excess heating (hot spot) even for a symmetric conductor. When coupled to the electrode phonons, CIFs drive different phonon heat flux into the two electrodes. First-princ...
Hsu, Hsiao-Ping; Binder, Kurt; Klushin, Leonid I; Skvortsov, Alexander M
2008-10-01
A polymer chain containing N monomers confined in a finite cylindrical tube of diameter D grafted at a distance L from the open end of the tube may undergo a rather abrupt transition, where part of the chain escapes from the tube to form a "crownlike" coil outside of the tube. When this problem is studied by Monte Carlo simulation of self-avoiding walks on the simple cubic lattice applying a cylindrical confinement and using the standard pruned-enriched Rosenbluth method (PERM), one obtains spurious results, however, with increasing chain length the transition gets weaker and weaker, due to insufficient sampling of the "escaped" states, as a detailed analysis shows. In order to solve this problem, a new variant of a biased sequential sampling algorithm with resampling is proposed, force-biased PERM: the difficulty of sampling both phases in the region of the first order transition with the correct weights is treated by applying a force at the free end pulling it out of the tube. Different strengths of this force need to be used and reweighting techniques are applied. Using rather long chains (up to N=18000 ) and wide tubes (up to D=29 lattice spacings), the free energy of the chain, its end-to-end distance, the number of "imprisoned" monomers can be estimated, as well as the order parameter and its distribution. It is suggested that this algorithm should be useful for other problems involving state changes of polymers, where the different states belong to rather disjunct "valleys" in the phase space of the system. PMID:18999448
Iterative Methods for the Force-based Quasicontinuum Approximation
Dobson, Matthew; Luskin, Mitchell; Ortner, Christoph
2009-01-01
Force-based atomistic-continuum hybrid methods are the only known pointwise consistent methods for coupling a general atomistic model to a finite element continuum model. For this reason, and due to their algorithmic simplicity, force-based coupling methods have become a popular class of atomistic-continuum hybrid models as well as other types of multiphysics models. However, the recently discovered unusual stability properties of the linearized force-based quasicontinuum (QCF) approximation,...
Kim, Kue Bum; Kwon, Hyun-Han; Han, Dawei
2015-11-01
In this paper, we present a comparative study of bias correction methods for regional climate model simulations considering the distributional parametric uncertainty underlying the observations/models. In traditional bias correction schemes, the statistics of the simulated model outputs are adjusted to those of the observation data. However, the model output and the observation data are only one case (i.e., realization) out of many possibilities, rather than being sampled from the entire population of a certain distribution due to internal climate variability. This issue has not been considered in the bias correction schemes of the existing climate change studies. Here, three approaches are employed to explore this issue, with the intention of providing a practical tool for bias correction of daily rainfall for use in hydrologic models ((1) conventional method, (2) non-informative Bayesian method, and (3) informative Bayesian method using a Weather Generator (WG) data). The results show some plausible uncertainty ranges of precipitation after correcting for the bias of RCM precipitation. The informative Bayesian approach shows a narrower uncertainty range by approximately 25-45% than the non-informative Bayesian method after bias correction for the baseline period. This indicates that the prior distribution derived from WG may assist in reducing the uncertainty associated with parameters. The implications of our results are of great importance in hydrological impact assessments of climate change because they are related to actions for mitigation and adaptation to climate change. Since this is a proof of concept study that mainly illustrates the logic of the analysis for uncertainty-based bias correction, future research exploring the impacts of uncertainty on climate impact assessments and how to utilize uncertainty while planning mitigation and adaptation strategies is still needed.
Employer loses bid to force insurer to pay in bias suit.
1997-05-30
Educational Testing Services (ETS) tried to force its insurer, Liberty Mutual Fire Insurance Company, to reimburse it for money paid to settle a lawsuit brought by [name removed], a California man fired in 1990. A U.S. District judge ruled that because [name removed] claimed he was fired due to his HIV status, Liberty Mutual was not liable. The discriminatory conduct alleged by [name removed] fell outside the scope of the insurance that ETS had purchased. In 1991, shortly after [name removed] sued, ETS made the first of three written requests to Liberty Mutual for defense and indemnity. The insurer refused or did not respond and in 1996, ETS sued Liberty Mutual, alleging breach of contract and bad faith. The judge ruled that Liberty Mutual owed no duty to defend against a lawsuit based on discriminatory acts and failure to accommodate an HIV-positive employee. PMID:11364346
Mundy, Peter D; Lake, Jason P; Carden, Patrick J C; Smith, Neal A; Lauder, Mike A
2016-03-01
There are two perceived criterion methods for measuring power output during the loaded countermovement jump (CMJ): the force platform method and the combined method (force platform + optoelectronic motion capture system). Therefore, the primary aim of the present study was to assess agreement between the force platform method and the combined method measurements of peak power and mean power output during the CMJ across a spectrum of loads. Forty resistance-trained team sport athletes performed maximal effort CMJ with additional loads of 0 (body mass only), 25, 50, 75 and 100% of body mass (BM). Bias was present for peak velocity, mean velocity, peak power and mean power at all loads investigated, and present for mean force up to 75% of BM. Peak velocity, mean velocity, peak power and mean power 95% ratio limits of agreement were clinically unacceptable at all loads investigated. The 95% ratio limits of agreement were widest at 0% of BM and decreased linearly as load increased. Therefore, the force platform method and the combined method cannot be used interchangeably for measuring power output during the loaded CMJ. As such, if power output is to be meaningfully investigated, a standardised method must be adopted. PMID:27075378
A scanning tunneling microscope break junction method with continuous bias modulation
Beall, Edward; Yin, Xing; Waldeck, David H.; Wierzbinski, Emil
2015-09-01
Single molecule conductance measurements on 1,8-octanedithiol were performed using the scanning tunneling microscope break junction method with an externally controlled modulation of the bias voltage. Application of an AC voltage is shown to improve the signal to noise ratio of low current (low conductance) measurements as compared to the DC bias method. The experimental results show that the current response of the molecule(s) trapped in the junction and the solvent media to the bias modulation can be qualitatively different. A model RC circuit which accommodates both the molecule and the solvent is proposed to analyze the data and extract a conductance for the molecule.Single molecule conductance measurements on 1,8-octanedithiol were performed using the scanning tunneling microscope break junction method with an externally controlled modulation of the bias voltage. Application of an AC voltage is shown to improve the signal to noise ratio of low current (low conductance) measurements as compared to the DC bias method. The experimental results show that the current response of the molecule(s) trapped in the junction and the solvent media to the bias modulation can be qualitatively different. A model RC circuit which accommodates both the molecule and the solvent is proposed to analyze the data and extract a conductance for the molecule. Electronic supplementary information (ESI) available: Additional current-time traces recorded for mesitylene, 2,4-dichlorotoluene, and 3,4-dichlorotoluene under different bias modulation frequencies, determined solvent capacitance values, and traces recorded under various geometrical constraints in the experimental cell. See DOI: 10.1039/c5nr04649a
Assessing response bias from missing quality of life data: The Heckman method
Directory of Open Access Journals (Sweden)
Spertus John A
2004-09-01
Full Text Available Abstract Background The objective of this study was to demonstrate the use of the Heckman two-step method to assess and correct for bias due to missing health related quality of life (HRQL surveys in a clinical study of acute coronary syndrome (ACS patients. Methods We analyzed data from 2,733 veterans with a confirmed diagnosis of acute coronary syndromes (ACS, including either acute myocardial infarction or unstable angina. HRQL outcomes were assessed by the Short-Form 36 (SF-36 health status survey which was mailed to all patients who were alive 7 months following ACS discharge. We created multivariable models of 7-month post-ACS physical and mental health status using data only from the 1,660 survey respondents. Then, using the Heckman method, we modeled survey non-response and incorporated this into our initial models to assess and correct for potential bias. We used logistic and ordinary least squares regression to estimate the multivariable selection models. Results We found that our model of 7-month mental health status was biased due to survey non-response, while the model for physical health status was not. A history of alcohol or substance abuse was no longer significantly associated with mental health status after controlling for bias due to non-response. Furthermore, the magnitude of the parameter estimates for several of the other predictor variables in the MCS model changed after accounting for bias due to survey non-response. Conclusion Recognition and correction of bias due to survey non-response changed the factors that we concluded were associated with HRQL seven months following hospital admission for ACS as well as the magnitude of some associations. We conclude that the Heckman two-step method may be a valuable tool in the assessment and correction of selection bias in clinical studies of HRQL.
A new method to measure galaxy bias by combining the density and weak lensing fields
Pujol, Arnau; Gaztañaga, Enrique; Amara, Adam; Refregier, Alexandre; Bacon, David J; Carretero, Jorge; Castander, Francisco J; Crocce, Martin; Fosalba, Pablo; Manera, Marc; Vikram, Vinu
2016-01-01
We present a new method to measure the redshift-dependent galaxy bias by combining information from the galaxy density field and the weak lensing field. This method is based on Amara et al. (2012), where they use the galaxy density field to construct a bias-weighted convergence field kg. The main difference between Amara et al. (2012) and our new implementation is that here we present another way to measure galaxy bias using tomography instead of bias parameterizations. The correlation between kg and the true lensing field k allows us to measure galaxy bias using different zero-lag correlations, such as / or /. This paper is the first that studies and systematically tests the robustness of this method in simulations. We use the MICE simulation suite, which includes a set of self-consistent N-body simulations, lensing maps, and mock galaxy catalogues. We study the accuracy and systematic uncertainties associated with the implementation of the method, and the regime where it is consistent with the linear galaxy...
He, Y Thomas; Ziemkiewicz, Paul F
2016-09-01
Aluminum is an important aquatic contaminant due to its ubiquity, toxicity and low regulatory discharge limits. Aluminum is mobilized in mining related, acidic drainage and is commonly a regulated pollutant. However, while aquatic toxicity studies and toxicity criteria are based on dissolved aluminum(Ald), discharge levels are, for statutory reasons, based on total recoverable aluminum (Alt). The rationale for using total recoverable aluminum recognizes the potential for the release of exchangeable, toxic cations or dissolution of metastable metal flocs in the event the discharge enters an acidic receiving stream. The digestion methods used in determining total recoverable metals are not meant to dissolve aluminosilicate clay particles but we found that they do, resulting in positively biased total recoverable aluminum values. This study explored the interaction between total suspended solids (TSS) and total recoverable aluminum using three digestion methods to evaluate which method introduced the least bias. Using field collected water and sediment samples from two coal mine drainage sites in Central West Virginia, three total recoverable digestion methods (USEPA Method 200.7, M1; USGS In-Bottle method, M2; and a Modified In-Bottle method, M3) were used to determine total recoverable aluminum across a range of total suspended solids concentrations. Baseline simulation experiments were conducted at pH 2.5, 3.5, 4.5 and 5.5 at different total suspended solids concentrations. Results indicated that dissolved aluminum did not respond to increasing total suspended solids concentrations while determined total recoverable aluminum increased with total suspended solids, indicating varying degrees of clay dissolution and, thus bias in the total recoverable aluminum concentration. While all three digestion methods overestimated total recoverable aluminum, at the same total suspended solids concentration, total recoverable aluminum extracted by USEPA Method 200.7 (M1) was
Better confidence intervals for left censored data using bias corrected bootstrap method
International Nuclear Information System (INIS)
Estimation of the 95% confidence intervals of the population parameters of small sized (say <= 30) environmental data samples under conventional statistical methodologies are error prone because the probability density function associated with the specified data sets, most of the times, is questionable. Therefore, in instances when the distribution of a statistic is unknown, nonparametric methods such as bootstrap override the conventional ones. The nonparametric (percentile) bootstrap method has been used to evaluate the confidence intervals of the mean. This paper describes the application of bias-corrected percentile bootstrap method that yields better confidence intervals than the percentile bootstrap method. An inter-comparative study of the two methods is also carried out. A case study with air activity data recorded from a specific Indian nuclear power plant is presented to support the superiority of bias corrected bootstrap method over the percentile bootstrap method and the conventional students -t method. (author)
Wang, Y. P.; Lu, Z. P.; Sun, D. S.; Wang, N.
2016-01-01
In order to better express the characteristics of satellite clock bias (SCB) and improve SCB prediction precision, this paper proposed a new SCB prediction model which can take physical characteristics of space-borne atomic clock, the cyclic variation, and random part of SCB into consideration. First, the new model employs a quadratic polynomial model with periodic items to fit and extract the trend term and cyclic term of SCB; then based on the characteristics of fitting residuals, a time series ARIMA ~(Auto-Regressive Integrated Moving Average) model is used to model the residuals; eventually, the results from the two models are combined to obtain final SCB prediction values. At last, this paper uses precise SCB data from IGS (International GNSS Service) to conduct prediction tests, and the results show that the proposed model is effective and has better prediction performance compared with the quadratic polynomial model, grey model, and ARIMA model. In addition, the new method can also overcome the insufficiency of the ARIMA model in model recognition and order determination.
von Bartheld, C.S.
2002-01-01
Investigators must choose between counting methods to quantify microscopic particles in tissues. The c o nventional profile-based ("model-based" or "2D-") counting methods have been criticized for their potential biases due to assumptions about shapes, sizes, and orientation of particles when converting profile counts into cell numbers. New stereological methods ("designbased" or "3D-") methods such as the optical disector or p hysical disector were initially i...
Force prediction in cold rolling mills by polynomial methods
Directory of Open Access Journals (Sweden)
Nicu ROMAN
2007-12-01
Full Text Available A method for steel and aluminium strip thickness control is provided including a new technique for predictive rolling force estimation method by statistic model based on polynomial techniques.
Directory of Open Access Journals (Sweden)
Xuhua Xia
2006-01-01
Full Text Available I show several types of topological biases in distance-based methods that use the least-squares method to evaluate branch lengths and the minimum evolution (ME or the Fitch-Margoliash (FM criterion to choose the best tree. For a 6-species tree, there are two tree shapes, one with three cherries (a cherry is a pair of adjacent leaves descending from the most recent common ancestor, and the other with two. When genetic distances are underestimated, the 3-cherry tree shape is favored with either the ME or FM criterion. When the genetic distances are overestimated, the ME criterion favors the 2-cherry tree, but the direction of bias with the FM criterion depends on whether negative branches are allowed, i.e. allowing negative branches favors the 3-cherry tree shape but disallowing negative branches favors the 2-cherry tree shape. The extent of the bias is explored by computer simulation of sequence evolution.
Double Force Compensation Method to Enhance the Performance of a Null Balance Force Sensor
Choi, In-Mook; Choi, Dong-June; Kim, Soo Hyun
2002-06-01
Microforce measurement is becoming more essential as precision industries such as biomedicine, precision chemistry, semiconductor manufacturing, and so forth develop. A null balance method has been introduced in order to improve on force measurement performances involving a loadcell. The null-balance type force sensor is analyzed and designed for the improvement of measurement performances. The measurement range and the resolution are dependent on the force generation capacity and the various error sources. These characteristics are estimated and verified according to the mechanical sensitivity and the force compensation sensitivity. Two different coil systems are designed and tested experimentally. Double force compensation is proposed in order to obtain a large range and high resolution. The measurement range of the large coil system and the resolution of the small one are fully realized by the double compensation method. After manufacturing, a range over 300 gf and resolution under ± 0.1 mgf were obtained by the double compensation method.
Müller, Marc F.; Thompson, Sally E.
2013-10-01
Estimating precipitation over large spatial areas remains a challenging problem for hydrologists. Sparse ground-based gauge networks do not provide a robust basis for interpolation, and the reliability of remote sensing products, although improving, is still imperfect. Current techniques to estimate precipitation rely on combining these different kinds of measurements to correct the bias in the satellite observations. We propose a novel procedure that, unlike existing techniques, (i) allows correcting the possibly confounding effects of different sources of errors in satellite estimates, (ii) explicitly accounts for the spatial heterogeneity of the biases and (iii) allows the use of non overlapping historical observations. The proposed method spatially aggregates and interpolates gauge data at the satellite grid resolution by focusing on parameters that describe the frequency and intensity of the rainfall observed at the gauges. The resulting gridded parameters can then be used to adjust the probability density function of satellite rainfall observations at each grid cell, accounting for spatial heterogeneity. Unlike alternate methods, we explicitly adjust biases on rainfall frequency in addition to its intensity. Adjusted rainfall distributions can then readily be applied as input in stochastic rainfall generators or frequency domain hydrological models. Finally, we also provide a procedure to use them to correct remotely sensed rainfall time series. We apply the method to adjust the distributions of daily rainfall observed by the TRMM satellite in Nepal, which exemplifies the challenges associated with a sparse gauge network and large biases due to complex topography. In a cross-validation analysis on daily rainfall from TRMM 3B42 v6, we find that using a small subset of the available gauges, the proposed method outperforms local rainfall estimations using the complete network of available gauges to directly interpolate local rainfall or correct TRMM by adjusting
Adhesion Force Measurements of Polymer Particles by Detachment Field Method
Institute of Scientific and Technical Information of China (English)
Masashi Nagayama; Nobuyasu Sakurai; Tatsuaki Wada; Manabu Takeuchi
2004-01-01
The adhesion force distributions of polymer particles to aluminum substrates were measured by the detachment field method. Polymer particles with conducting surface treatment were used for the measurements.Further the conventional detachment field method was modified to be applicable to the adhesion force measurements of a single particle. The adhesion force of the polymer particles increased with an increase in relative humidity. The surface roughness of the substrate influenced the adhesion forces of particles significantly. The influence of the CF4 plasma treatment of the polymer particles and thin layer coating of the substrate surface on the adhesion forces of the polymer particles was also studied, and factors affecting adhesion forces of polymer particles are discussed.
Integrated Force Method Solution to Indeterminate Structural Mechanics Problems
Patnaik, Surya N.; Hopkins, Dale A.; Halford, Gary R.
2004-01-01
Strength of materials problems have been classified into determinate and indeterminate problems. Determinate analysis primarily based on the equilibrium concept is well understood. Solutions of indeterminate problems required additional compatibility conditions, and its comprehension was not exclusive. A solution to indeterminate problem is generated by manipulating the equilibrium concept, either by rewriting in the displacement variables or through the cutting and closing gap technique of the redundant force method. Compatibility improvisation has made analysis cumbersome. The authors have researched and understood the compatibility theory. Solutions can be generated with equal emphasis on the equilibrium and compatibility concepts. This technique is called the Integrated Force Method (IFM). Forces are the primary unknowns of IFM. Displacements are back-calculated from forces. IFM equations are manipulated to obtain the Dual Integrated Force Method (IFMD). Displacement is the primary variable of IFMD and force is back-calculated. The subject is introduced through response variables: force, deformation, displacement; and underlying concepts: equilibrium equation, force deformation relation, deformation displacement relation, and compatibility condition. Mechanical load, temperature variation, and support settling are equally emphasized. The basic theory is discussed. A set of examples illustrate the new concepts. IFM and IFMD based finite element methods are introduced for simple problems.
Directory of Open Access Journals (Sweden)
Janja Novak
Full Text Available Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias. Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, using two different handling methods, as previous studies have shown that standard tail handling of mice increases physiological and behavioural measures of anxiety compared to cupped handling. Therefore, we hypothesised that tail handled mice would display a negative cognitive bias. We handled 28 female CD-1 mice for 16 weeks using either tail handling or cupped handling. The mice were then trained in an eight arm radial maze, where two adjacent arms predicted a positive outcome (darkness and food, while the two opposite arms predicted a negative outcome (no food, white noise and light. After six days of training, the mice were also given access to the four previously unavailable intermediate ambiguous arms of the radial maze and tested for cognitive bias. We were unable to validate this test, as mice from both handling groups displayed a similar pattern of exploration. Furthermore, we examined whether maze exploration is affected by the expression of stereotypic behaviour in the home cage. Mice with higher levels of stereotypic behaviour spent more time in positive arms and avoided ambiguous arms, displaying a negative cognitive bias. While this test needs further validation, our results indicate that it may allow the assessment of affective state in mice with minimal training-a major confound in current cognitive bias paradigms.
Novak, Janja; Bailoo, Jeremy D; Melotti, Luca; Rommen, Jonas; Würbel, Hanno
2015-01-01
Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, using two different handling methods, as previous studies have shown that standard tail handling of mice increases physiological and behavioural measures of anxiety compared to cupped handling. Therefore, we hypothesised that tail handled mice would display a negative cognitive bias. We handled 28 female CD-1 mice for 16 weeks using either tail handling or cupped handling. The mice were then trained in an eight arm radial maze, where two adjacent arms predicted a positive outcome (darkness and food), while the two opposite arms predicted a negative outcome (no food, white noise and light). After six days of training, the mice were also given access to the four previously unavailable intermediate ambiguous arms of the radial maze and tested for cognitive bias. We were unable to validate this test, as mice from both handling groups displayed a similar pattern of exploration. Furthermore, we examined whether maze exploration is affected by the expression of stereotypic behaviour in the home cage. Mice with higher levels of stereotypic behaviour spent more time in positive arms and avoided ambiguous arms, displaying a negative cognitive bias. While this test needs further validation, our results indicate that it may allow the assessment of affective state in mice with minimal training-a major confound in current cognitive bias paradigms. PMID:26154309
Directory of Open Access Journals (Sweden)
Ju Hyoung Lee
2015-12-01
Full Text Available Bias correction is a very important pre-processing step in satellite data assimilation analysis, as data assimilation itself cannot circumvent satellite biases. We introduce a retrieval algorithm-specific and spatially heterogeneous Instantaneous Field of View (IFOV bias correction method for Soil Moisture and Ocean Salinity (SMOS soil moisture. To the best of our knowledge, this is the first paper to present the probabilistic presentation of SMOS soil moisture using retrieval ensembles. We illustrate that retrieval ensembles effectively mitigated the overestimation problem of SMOS soil moisture arising from brightness temperature errors over West Africa in a computationally efficient way (ensemble size: 12, no time-integration. In contrast, the existing method of Cumulative Distribution Function (CDF matching considerably increased the SMOS biases, due to the limitations of relying on the imperfect reference data. From the validation at two semi-arid sites, Benin (moderately wet and vegetated area and Niger (dry and sandy bare soils, it was shown that the SMOS errors arising from rain and vegetation attenuation were appropriately corrected by ensemble approaches. In Benin, the Root Mean Square Errors (RMSEs decreased from 0.1248 m3/m3 for CDF matching to 0.0678 m3/m3 for the proposed ensemble approach. In Niger, the RMSEs decreased from 0.14 m3/m3 for CDF matching to 0.045 m3/m3 for the ensemble approach.
Fu, Haohao; Shao, Xueguang; Chipot, Christophe; Cai, Wensheng
2016-08-01
Proper use of the adaptive biasing force (ABF) algorithm in free-energy calculations needs certain prerequisites to be met, namely, that the Jacobian for the metric transformation and its first derivative be available and the coarse variables be independent and fully decoupled from any holonomic constraint or geometric restraint, thereby limiting singularly the field of application of the approach. The extended ABF (eABF) algorithm circumvents these intrinsic limitations by applying the time-dependent bias onto a fictitious particle coupled to the coarse variable of interest by means of a stiff spring. However, with the current implementation of eABF in the popular molecular dynamics engine NAMD, a trajectory-based post-treatment is necessary to derive the underlying free-energy change. Usually, such a posthoc analysis leads to a decrease in the reliability of the free-energy estimates due to the inevitable loss of information, as well as to a drop in efficiency, which stems from substantial read-write accesses to file systems. We have developed a user-friendly, on-the-fly code for performing eABF simulations within NAMD. In the present contribution, this code is probed in eight illustrative examples. The performance of the algorithm is compared with traditional ABF, on the one hand, and the original eABF implementation combined with a posthoc analysis, on the other hand. Our results indicate that the on-the-fly eABF algorithm (i) supplies the correct free-energy landscape in those critical cases where the coarse variables at play are coupled to either each other or to geometric restraints or holonomic constraints, (ii) greatly improves the reliability of the free-energy change, compared to the outcome of a posthoc analysis, and (iii) represents a negligible additional computational effort compared to regular ABF. Moreover, in the proposed implementation, guidelines for choosing two parameters of the eABF algorithm, namely the stiffness of the spring and the mass
WEIGHING GALAXY CLUSTERS WITH GAS. I. ON THE METHODS OF COMPUTING HYDROSTATIC MASS BIAS
International Nuclear Information System (INIS)
Mass estimates of galaxy clusters from X-ray and Sunyeav-Zel'dovich observations assume the intracluster gas is in hydrostatic equilibrium with their gravitational potential. However, since galaxy clusters are dynamically active objects whose dynamical states can deviate significantly from the equilibrium configuration, the departure from the hydrostatic equilibrium assumption is one of the largest sources of systematic uncertainties in cluster cosmology. In the literature there have been two methods for computing the hydrostatic mass bias based on the Euler and the modified Jeans equations, respectively, and there has been some confusion about the validity of these two methods. The word 'Jeans' was a misnomer, which incorrectly implies that the gas is collisionless. To avoid further confusion, we instead refer these methods as 'summation' and 'averaging' methods respectively. In this work, we show that these two methods for computing the hydrostatic mass bias are equivalent by demonstrating that the equation used in the second method can be derived from taking spatial averages of the Euler equation. Specifically, we identify the correspondences of individual terms in these two methods mathematically and show that these correspondences are valid to within a few percent level using hydrodynamical simulations of galaxy cluster formation. In addition, we compute the mass bias associated with the acceleration of gas and show that its contribution is small in the virialized regions in the interior of galaxy clusters, but becomes non-negligible in the outskirts of massive galaxy clusters. We discuss future prospects of understanding and characterizing biases in the mass estimate of galaxy clusters using both hydrodynamical simulations and observations and their implications for cluster cosmology
A novel adaptive force control method for IPMC manipulation
Hao, Lina; Sun, Zhiyong; Li, Zhi; Su, Yunquan; Gao, Jianchao
2012-07-01
IPMC is a type of electro-active polymer material, also called artificial muscle, which can generate a relatively large deformation under a relatively low input voltage (generally speaking, less than 5 V), and can be implemented in a water environment. Due to these advantages, IPMC can be used in many fields such as biomimetics, service robots, bio-manipulation, etc. Until now, most existing methods for IPMC manipulation are displacement control not directly force control, however, under most conditions, the success rate of manipulations for tiny fragile objects is limited by the contact force, such as using an IPMC gripper to fix cells. Like most EAPs, a creep phenomenon exists in IPMC, of which the generated force will change with time and the creep model will be influenced by the change of the water content or other environmental factors, so a proper force control method is urgently needed. This paper presents a novel adaptive force control method (AIPOF control—adaptive integral periodic output feedback control), based on employing a creep model of which parameters are obtained by using the FRLS on-line identification method. The AIPOF control method can achieve an arbitrary pole configuration as long as the plant is controllable and observable. This paper also designs the POF and IPOF controller to compare their test results. Simulation and experiments of micro-force-tracking tests are carried out, with results confirming that the proposed control method is viable.
Multilinear Biased Discriminant Analysis: A Novel Method for Facial Action Unit Representation
Khademi, Mahmoud; Manzuri-Shalmani, Mohammad T
2010-01-01
In this paper a novel efficient method for representation of facial action units by encoding an image sequence as a fourth-order tensor is presented. The multilinear tensor-based extension of the biased discriminant analysis (BDA) algorithm, called multilinear biased discriminant analysis (MBDA), is first proposed. Then, we apply the MBDA and two-dimensional BDA (2DBDA) algorithms, as the dimensionality reduction techniques, to Gabor representations and the geometric features of the input image sequence respectively. The proposed scheme can deal with the asymmetry between positive and negative samples as well as curse of dimensionality dilemma. Extensive experiments on Cohn-Kanade database show the superiority of the proposed method for representation of the subtle changes and the temporal information involved in formation of the facial expressions. As an accurate tool, this representation can be applied to many areas such as recognition of spontaneous and deliberate facial expressions, multi modal/media huma...
Influence of force-based crosstalk on the 'wedge method' in lateral force microscopy
International Nuclear Information System (INIS)
The lateral force mode of an atomic force microscope is a contact-based measurement where the cantilever moves laterally in order to contribute to the lateral component of the tip–surface interaction. An accurate quantitative measure is difficult to achieve and is subject to the calibration of a model of the machine such that the output signal is related to the contact forces. Currently available models and calibration methods do not consider the existence of crosstalk. The influence of the latter on the measurement is not clearly identified and raises the question of the result's accuracy. In this paper a definition of the crosstalk is given and the diversity of the crosstalk briefly presented. A first-order, two-dimensional model of the system that includes the force-based crosstalk is presented. The model is used to simulate a calibration method known as the 'wedge method'. A parametric study is carried out to evaluate the calibration errors that can be made by the 'wedge method'. Results show that force-based crosstalk can have a noticeable influence on the calibration as well as on the estimated friction coefficient
On Stein's method for products of normal random variables and zero bias couplings
Gaunt, Robert E.
2013-01-01
In this paper we extend Stein's method to the distribution of the product of $n$ independent mean zero normal random variables. A Stein equation is obtained for this class of distributions, which reduces to the classical normal Stein equation in the case $n=1$. This Stein equation motivates a generalisation of the zero bias transformation. We establish properties of this new transformation, and illustrate how they may be used together with the Stein equation to assess distributional distances...
MCNP/TORT coupling vs. MCNP biasing transport methods for PWR applications
International Nuclear Information System (INIS)
This paper presents the coupling methodology of the Monte Carlo code MCNP5 and the deterministic SN TORT, to meet the AREVA needs for PWR reactors analysis, but also BWR and GEN IV reactors. In general the long-range transport of neutron and gamma particles outside the core using only Monte Carlo calculations requires prohibitive computation time, if no biasing is included, to guide the particle population to spread towards the chosen target. This biasing becomes essential, if computing resources are limited. The disadvantage of this approach lies in the preparation of such biasing, particularly for non-standard configurations. An alternate method is proposed, with the coupling of the two codes specified above. The MCNP5 code is used to calculate the in-core neutron or gamma sources. The neutron/gamma particles are transported to the outside of the core and deposited on a predetermined outer surface. The surface source is subsequently propagated in SN/finite difference method. The convergence of the SN calculations is relatively short (few hours), which leads to a result in only about a half day, including MCNP5. A first physical validation of this coupling is obtained for the N4 French reactor. The thermal epithermal and fast fluxes are evaluated. A very good agreement is obtained for the neutron flux >1 eV; the deviations are below 5% for this part of spectrum. Finally a comparison is presented to demonstrate the interest or not of the coupling MCNP/TORT methodology vs. existing biasing methods in MCNP5. (author)
An improved method for calculation of interface pressure force in PLIC-VOF methods
International Nuclear Information System (INIS)
Conventional methods for the modeling of surface tension force in Piecewise Linear Interface Calculation-Volume of Fluid (PLIC-VOF) methods, such as Continuum Surface Force (CSF), Continuum Surface Stress (CSS) and also Meier's method, convert the surface tension force into a body force. Not only do they include the force in the interfacial cells but also in the neighboring cells. Thus they produce spurious currents. Also the pressure jump, due to the surface tension, is not calculated accurately in these methods. In this paper a more accurate method for the application of interface force in the computational modeling of free surfaces and interfaces which use PLIC-VOF methods is developed. This method is based on the evaluation of the surface tension force only in the interfacial cells and not the neighboring cells. Also the normal and the interface surface area needed for the calculation of the surface tension force is calculated more accurately. The present method is applied to a two-dimensional motionless drop of liquid and a bubble of gas as well as a non-circular two-dimensional drop, which oscillates due to the surface tension force, in an initially stagnant fluid with no gravity force. The results are compared with the results of the cases when CSF, CSS and Meier's methods are used. It is shown that the present method calculates pressure jump at the interface more accurately and produces less spurious currents comparing to CSS an CSF models. (author)
Seo, Ji-Hoon; Kim, Gang-Jun; Son, Donghee; Lee, Nam-Hyun; Kang, Yongha; Kang, Bongkoo
2016-08-01
We propose a method to predict the length dependency of the magnitude of degradation caused by negative bias temperature instability (NBTI) stress applied to a p-MOSFET. Threshold voltage degradation ΔV th varied according to the drain bias V d, during the measurement of drain current I d. The depletion length L dep into the channel was calculated based on a particular V d value and the channel doping concentration. L dep was used to extract the channel edge region length L edge, then the center channel region length L cen was obtained by subtracting L edge from the gate length L gate. We proposed an equation that uses L dep, L cen, L edge and degree of ΔV th variation to calculate ΔV th according to L gate while the p-MOSFET is under NBTI stress. Equation estimates of ΔV th at different L gate were similar to measurements.
A novel method for correcting scanline-observational bias of discontinuity orientation.
Huang, Lei; Tang, Huiming; Tan, Qinwen; Wang, Dingjian; Wang, Liangqing; Ez Eldin, Mutasim A M; Li, Changdong; Wu, Qiong
2016-01-01
Scanline observation is known to introduce an angular bias into the probability distribution of orientation in three-dimensional space. In this paper, numerical solutions expressing the functional relationship between the scanline-observational distribution (in one-dimensional space) and the inherent distribution (in three-dimensional space) are derived using probability theory and calculus under the independence hypothesis of dip direction and dip angle. Based on these solutions, a novel method for obtaining the inherent distribution (also for correcting the bias) is proposed, an approach which includes two procedures: 1) Correcting the cumulative probabilities of orientation according to the solutions, and 2) Determining the distribution of the corrected orientations using approximation methods such as the one-sample Kolmogorov-Smirnov test. The inherent distribution corrected by the proposed method can be used for discrete fracture network (DFN) modelling, which is applied to such areas as rockmass stability evaluation, rockmass permeability analysis, rockmass quality calculation and other related fields. To maximize the correction capacity of the proposed method, the observed sample size is suggested through effectiveness tests for different distribution types, dispersions and sample sizes. The performance of the proposed method and the comparison of its correction capacity with existing methods are illustrated with two case studies. PMID:26961249
Detection of forced oscillations in power systems with multichannel methods
Energy Technology Data Exchange (ETDEWEB)
Follum, James D. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
2015-09-30
The increasing availability of high fidelity, geographically dispersed measurements in power systems improves the ability of researchers and engineers to study dynamic behaviors in the grid. One such behavior that is garnering increased attention is the presence of forced oscillations. Power system engineers are interested in forced oscillations because they are often symptomatic of the malfunction or misoperation of equipment. Though the resulting oscillation is not always large in amplitude, the root cause may be serious. In this report, multi-channel forced oscillation detection methods are developed. These methods leverage previously developed detection approaches based on the periodogram and spectral-coherence. Making use of geographically distributed channels of data is shown to improved detection performance and shorten the delay before an oscillation can be detected in the online environment. Results from simulated and measured power system data are presented.
Laser measurement method of forced vibration in optical systems
International Nuclear Information System (INIS)
A forced vibration measurement method by laser combining the laser signal and high frequency CCD in optical systems is introduced. The method solves the conversion problem between the vibration signal and laser signal in optical systems, which can not only measure the impact of vibration on the beam stability, but also acquire the frequency characteristics of vibration signals. Forced vibration in an optical system is measured when the frequencies of vibration signals are 150 Hz and 200 Hz by using the method and the attributes of the vibration signals obtained fits those of the input signals. Test and analysis results demonstrate that the method has a time amplitude uncertainty of 6.25 μm and frequency resolution of 2 Hz. The handy and efficient method, whose measurement is precise, has been applied to the beam pointing stability study of the multiplexing excimer MOPA laser targeting test platform accordingly. (authors)
Modeling Enzymatic Transition States by Force Field Methods
DEFF Research Database (Denmark)
Hansen, Mikkel Bo; Jensen, Hans Jørgen Aagaard; Jensen, Frank
2009-01-01
The SEAM method, which models a transition structure as a minimum on the seam of two diabatic surfaces represented by force field functions, has been used to generate 20 transition structures for the decarboxylation of orotidine by the orotidine-5'-monophosphate decarboxylase enzyme. The dependence...... by various electronic structure methods, where part of the enzyme is represented by a force field description and the effects of the solvent are represented by a continuum model. The relative energies vary by several hundreds of kJ/mol between the transition structures, and tests showed that a large part...... of this variation is due to changes in the enzyme structure at distances more than 5 Å from the active site. There are significant differences between the results obtained by pure quantum methods and those from mixed quantum and molecular mechanics methods....
A method for additive bias correction in cross-cultural surveys
DEFF Research Database (Denmark)
Scholderer, Joachim; Grunert, Klaus G.; Brunsø, Karen
2001-01-01
Measurement bias in cross-cultural surveys can seriously threaten the validity of hypothesis tests. Direct comparisons of means depend on the assumption that differences in observed variables reflect differences in the underlying constructs, and not an additive bias that may be caused by cultural...... additive bias from cross-cultural data. The procedure involves four steps: (1) embed a potentially biased item in a factor-analytic measurement model, (2) test for the existence of additive bias between populations, (3) use the factor-analytic model to estimate the magnitude of the bias, and (4) replace...
Witzke, V; Favier, B
2016-01-01
Shear flows are ubiquitous in astrophysical objects including planetary and stellar interiors, where their dynamics can have significant impact on thermo-chemical processes. Investigating the complex dynamics of shear flows requires numerical calculations that provide a long time evolution of the system. To achieve a sufficiently long lifetime in a local numerical model the system has to be forced externally. However, at present, there exist several different forcing methods to sustain large-scale shear flows in local models. In this paper we examine and compare various methods used in the literature in order to resolve their respective applicability and limitations. These techniques are compared during the exponential growth phase of a shear flow instability, such as the Kelvin-Helmholtz (KH) instability, and some are examined during the subsequent non-linear evolution. A linear stability analysis provides reference for the growth rate of the most unstable modes in the system and a detailed analysis of the e...
DEFF Research Database (Denmark)
Thorson, James T.; Kristensen, Kasper
2016-01-01
Statistical models play an important role in fisheries science when reconciling ecological theory with available data for wild populations or experimental studies. Ecological models increasingly include both fixed and random effects, and are often estimated using maximum likelihood techniques...... is calculated as a nonlinear function of random effects. We therefore describe and evaluate a new "epsilon" estimator as a generic bias-correction estimator for derived quantities. We use simulated data to compare the epsilon-method with an existing bias-correction algorithm for estimating...... recruitment in four configurations of an age-structured population dynamics model. This simulation experiment shows that the epsilon-method and the existing bias-correction method perform equally well in data-rich contexts, but the epsilon-method is slightly less biased in data-poor contexts. We then apply...
Witzke, V.; Silvers, L. J.; Favier, B.
2016-08-01
Shear flows are ubiquitous in astrophysical objects including planetary and stellar interiors, where their dynamics can have significant impact on thermo-chemical processes. Investigating the complex dynamics of shear flows requires numerical calculations that provide a long time evolution of the system. To achieve a sufficiently long lifetime in a local numerical model the system has to be forced externally. However, at present, there exist several different forcing methods to sustain large-scale shear flows in local models. In this paper we examine and compare various methods used in the literature in order to resolve their respective applicability and limitations. These techniques are compared during the exponential growth phase of a shear flow instability, such as the Kelvin-Helmholtz (KH) instability, and some are examined during the subsequent non-linear evolution. A linear stability analysis provides reference for the growth rate of the most unstable modes in the system and a detailed analysis of the energetics provides a comprehensive understanding of the energy exchange during the system's evolution. Finally, we discuss the pros and cons of each forcing method and their relation with natural mechanisms generating shear flows.
Gamble, Reed
1989-01-01
Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)
Energy Technology Data Exchange (ETDEWEB)
Kim, D.W.; Kim, J.G.; Kim, A.R. [Changwon National University, 9 sarim-dong, Changwon 641-773 (Korea, Republic of); Park, M., E-mail: paku@changwon.ac.k [Changwon National University, 9 sarim-dong, Changwon 641-773 (Korea, Republic of); Yu, I.K. [Changwon National University, 9 sarim-dong, Changwon 641-773 (Korea, Republic of); Sim, K.D.; Kim, S.H.; Lee, S.J.; Cho, J.W. [Superconducting Device and Cryogenics Group, Korea Electrotechnology Research Institute, Changwon, 641-120 (Korea, Republic of); Won, Y.J. [Korea Electric Power Corporation, 411, youngdong-dearo, Gangnam-gu, Seoul (Korea, Republic of)
2010-11-01
The authors calculated the loss of the High Temperature Superconducting (HTS) model cable using Norris ellipse formula, and measured the loss of the model cable experimentally. Two kinds of measuring method are used. One is the electrical method, and the other is the calorimetric method. The electrical method can be used only in AC condition. But the calorimetric method can be used in both AC and DC bias conditions. In order to propose an effective measuring approach for Ripple Dependent Loss (RDL) under DC bias condition using the calorimetric method, Bismuth Strontium Calcium Copper Oxide (BSCCO) wires were used for the HTS model cable, and the SUS tapes were used as a heating tape to make the same pattern of the temperature profiles as in the electrical method without the transport current. The temperature-loss relations were obtained by the electrical method, and then applied to the calorimetric method by which the RDL under DC bias condition was well estimated.
International Nuclear Information System (INIS)
The authors calculated the loss of the High Temperature Superconducting (HTS) model cable using Norris ellipse formula, and measured the loss of the model cable experimentally. Two kinds of measuring method are used. One is the electrical method, and the other is the calorimetric method. The electrical method can be used only in AC condition. But the calorimetric method can be used in both AC and DC bias conditions. In order to propose an effective measuring approach for Ripple Dependent Loss (RDL) under DC bias condition using the calorimetric method, Bismuth Strontium Calcium Copper Oxide (BSCCO) wires were used for the HTS model cable, and the SUS tapes were used as a heating tape to make the same pattern of the temperature profiles as in the electrical method without the transport current. The temperature-loss relations were obtained by the electrical method, and then applied to the calorimetric method by which the RDL under DC bias condition was well estimated.
Scalable force directed graph layout algorithms using fast multipole methods
Yunis, Enas
2012-06-01
We present an extension to ExaFMM, a Fast Multipole Method library, as a generalized approach for fast and scalable execution of the Force-Directed Graph Layout algorithm. The Force-Directed Graph Layout algorithm is a physics-based approach to graph layout that treats the vertices V as repelling charged particles with the edges E connecting them acting as springs. Traditionally, the amount of work required in applying the Force-Directed Graph Layout algorithm is O(|V|2 + |E|) using direct calculations and O(|V| log |V| + |E|) using truncation, filtering, and/or multi-level techniques. Correct application of the Fast Multipole Method allows us to maintain a lower complexity of O(|V| + |E|) while regaining most of the precision lost in other techniques. Solving layout problems for truly large graphs with millions of vertices still requires a scalable algorithm and implementation. We have been able to leverage the scalability and architectural adaptability of the ExaFMM library to create a Force-Directed Graph Layout implementation that runs efficiently on distributed multicore and multi-GPU architectures. © 2012 IEEE.
Selva Kumar, C; Nair, Rahul R; Sivaramakrishnan, K G; Ganesh, D; Janarthanan, S; Arunachalam, M; Sivaruban, T
2012-12-01
Forces that influence the evolution of synonymous codon usage bias are analyzed in six species of three basal orders of aquatic insects. The rationale behind choosing six species of aquatic insects (three from Ephemeroptera, one from Plecoptera, and two from Odonata) for the present analysis is based on phylogenetic position at the basal clades of the Order Insecta facilitating the understanding of the evolution of codon bias and of factors shaping codon usage patterns in primitive clades of insect lineages and their subtle differences in some of their ecological and environmental requirements in terms of habitat-microhabitat requirements, altitudinal preferences, temperature tolerance ranges, and consequent responses to climate change impacts. The present analysis focuses on open reading frames of the 13 protein-coding genes in the mitochondrial genome of six carefully chosen insect species to get a comprehensive picture of the evolutionary intricacies of codon bias. In all the six species, A and T contents are observed to be significantly higher than G and C, and are used roughly equally. Since transcription hypothesis on codon usage demands A richness and T poorness, it is quite likely that mutation pressure may be the key factor associated with synonymous codon usage (SCU) variations in these species because the mutation hypothesis predicts AT richness and GC poorness in the mitochondrial DNA. Thus, AT-biased mutation pressure seems to be an important factor in framing the SCU variation in all the selected species of aquatic insects, which in turn explains the predominance of A and T ending codons in these species. This study does not find any association between microhabitats and codon usage variations in the mitochondria of selected aquatic insects. However, this study has identified major forces, such as compositional constraints and mutation pressure, which shape patterns of codon usage in mitochondrial genes in the primitive clades of insect lineages. PMID
Forced vibration of flexible body systems. A dynamic stiffness method
Liu, T. S.; Lin, J. C.
1993-10-01
Due to the development of high speed machinery, robots, and aerospace structures, the research of flexible body systems undergoing both gross motion and elastic deformation has seen increasing importance. The finite element method and modal analysis are often used in formulating equations of motion for dynamic analysis of the systems which entail time domain, forced vibration analysis. This study develops a new method based on dynamic stiffness to investigate forced vibration of flexible body systems. In contrast to the conventional finite element method, shape functions and stiffness matrices used in this study are derived from equations of motion for continuum beams. Hence, the resulting shape functions are named as dynamic shape functions. By applying the dynamic shape functions, the mass and stiffness matrices of a beam element are derived. The virtual work principle is employed to formulate equations of motion. Not only the coupling of gross motion and elastic deformation, but also the stiffening effect of axial forces is taken into account. Simulation results of a cantilever beam, a rotating beam, and a slider crank mechanism are compared with the literature to verify the proposed method.
Energy Technology Data Exchange (ETDEWEB)
Newman, W.I. (California Univ., Los Angeles, CA (USA) Los Alamos National Lab., NM (USA)); Haynes, M.P.; Terzian, Y. (Cornell Univ., Ithaca, NY (USA))
1991-01-01
The Power Spectrum Analysis'' method developed by Yu and Peebles has been widely employed as a technique for establishing the existence of periodicities. This method generates a sequence of random numbers from observational data which, it was claimed, is exponentially distributed with unit mean and variance, essentially independent of the distribution of the original data. We show that the derived random process preserves a subtle imprint of the original distribution, rendering the derived process nonstationary and producing a small but systematic bias in the usual estimate of the mean and variance. Although the derived variable may be reasonably described by an exponential distribution, the tail of the distribution is far removed from that an exponential, thereby rendering statistical inference and confidence testing based on the tail of the distribution completely unreliable. 22 refs.
GBIQ: a non-arbitrary, non-biased method for quantification of fluorescent images
Ninomiya, Youichirou; Zhao, Wei; Saga, Yumiko
2016-01-01
Non-arbitrary and non-biased quantification of fluorescent images is an essential tool for the data-centric approach to biological systems. Typical application is high-content analysis, where various phenotypic changes in cellular components and/or morphology are measured from fluorescent image data. A standard protocol to detect cellular phenotypes is cell-segmentation, in which boundaries of cellular components, such as cell nucleus and plasma membrane, are first identified to define cell segments, then acquiring various phenotypic data of each segment. To achieve reliable outcome, cell-segmentation requires manual adjustments of many parameters; this requirement could hamper automated image processing in high-throughput workflow, whose quantification must be non-arbitrary and non-biased. As a practical alternative to the segmentation-based method, we developed GBIQ (Grid Based Image Quantification), which allows comparison of cellular information without identification of single cells. GBIQ divides an image with tiles of fixed size grids and records statistics of the grids with their location coordinates, minimizing arbitrary intervenes. GBIQ requires only one parameter (size of grid) to be set; nonetheless it robustly produces results suitable for further statistical evaluation. The simplicity of GBIQ allows it to be readily implemented in an automated high-throughput image analysis workflow. PMID:27211912
Comparison of two bias correction methods for precipitation simulated with a regional climate model
Tschöke, Gabriele Vanessa; Kruk, Nadiane Smaha; de Queiroz, Paulo Ivo Braga; Chou, Sin Chan; de Sousa Junior, Wilson Cabral
2015-11-01
This study evaluates the performance of two bias correction techniques—power transformation and gamma distribution adjustment—for Eta regional climate model (RCM) precipitation simulations. For the gamma distribution adjustment, the number of dry days is not taken as a fixed parameter; rather, we propose a new methodology for handling dry days. We consider two cases: the first case is defined as having a greater number of simulated dry days than the observed number, and the second case is defined as the opposite. The present climate period was divided into calibration and validation sets. We evaluate the results of the two bias correction techniques using the Kolmogorov-Smirnov nonparametric test and the sum of the differences between the cumulative distribution curves. These tests show that both correction techniques were effective in reducing errors and consequently improving the reliability of the simulations. However, the gamma distribution correction method proved to be more efficient, particularly in reducing the error in the number of dry days.
Hydrological modeling as an evaluation tool of EURO-CORDEX RCMs and bias correction methods
Hakala, Kirsti; Seibert, Jan; Addor, Nans
2016-04-01
This research explores the impacts of climate change on catchment discharge and addresses the challenge of characterizing and communicating their uncertainties. It particularly focuses on the integrated evaluation of EURO-CORDEX regional climate model simulations, using hydrological modeling at the catchment scale. For the evaluation of the various RCMs combined with different bias correction operations there are two main approaches: 1) Separate evaluation of the statistical properties of each climate variable in terms of its statistical properties such as annual mean, seasonal variation, frequency of extreme events. This first approach is the standard way to evaluate RCM runs and bias correction methods. It also prevails by far in the literature. Here we introduce an alternative evaluation approach, which relies on hydrological modeling, 2) Combined evaluation of the different variables at the catchment scale; that is the evaluation is based on hydrological simulation results, which integrate the different variables (mainly temperature, precipitation and evaporation). Although more time demanding, this second approach has a critical advantage in that it allows a focus on the statistical properties of the climate variables which are most important for catchment-scale runoff. We rely on the semi-distributed hydrological model HBV and apply it to Swiss catchments representative of different hydrological regimes and expected responses to climate change. This research investigates both approaches, however the second approach will be discussed in greater depth as an elegant way to consider the multitude of factors relevant for hydrological modeling all at once.
Papadimitriou, Lamprini V.; Koutroulis, Aristeidis G.; Grillakis, Manolis G.; Tsanis, Ioannis K.
2016-05-01
Climate models project a much more substantial warming than the 2 °C target under the more probable emission scenarios, making higher-end scenarios increasingly plausible. Freshwater availability under such conditions is a key issue of concern. In this study, an ensemble of Euro-CORDEX projections under RCP8.5 is used to assess the mean and low hydrological states under +4 °C of global warming for the European region. Five major European catchments were analysed in terms of future drought climatology and the impact of +2 °C versus +4 °C global warming was investigated. The effect of bias correction of the climate model outputs and the observations used for this adjustment was also quantified. Projections indicate an intensification of the water cycle at higher levels of warming. Even for areas where the average state may not considerably be affected, low flows are expected to reduce, leading to changes in the number of dry days and thus drought climatology. The identified increasing or decreasing runoff trends are substantially intensified when moving from the +2 to the +4° of global warming. Bias correction resulted in an improved representation of the historical hydrology. It is also found that the selection of the observational data set for the application of the bias correction has an impact on the projected signal that could be of the same order of magnitude to the selection of the Global Climate Model (GCM).
Atomic force microscopy in biomedical research - Methods and protocols
Directory of Open Access Journals (Sweden)
CarloAlberto Redi
2011-11-01
Full Text Available Pier Carlo Braga and Davide Ricci are old friends not only for those researchers familiar with Atomic force microscopy (AFM but also for those beginners (like the undersigned that already enthusiastically welcomed their 2004 edition (for the same Humana press printing types of Atomic force microscopy: Biomedical methods and applications, eventhough I never had used the AFM. That book was much intended to overview the possible AFM applications for a wide range of readers so that they can be in some way stimulated toward the AFM use. In fact, the great majority of scientists is afraid both of the technology behind AFM (that is naturally thought highly demanding in term of concepts not so familiar to biologists and physicians and of the financial costs: both these two factors are conceived unapproachable by the medium range granted scientist usually not educated in terms of biophysics and electronic background....
A method for adjusting gender bias in neonatal tetanus reports in Egypt 1991.
Silvers, M J; Haddy, R
2002-04-01
Reports of neonatal tetanus (NT) disease, common in developing countries, often suffers from gender bias because male infants are brought to health facilities while females are attended at home. Using existing health data we applied reasonable assumptions to estimate the true incidence of NT economically. To adjust for gender disparities in national reporting, we ignored the number of female NT cases and doubled the number for males. Governorates with similar demographic risk profiles for NT were assigned to one of six groups. The highest incidence rate within the group was determined and applied to the number of live births represented by the group. Other internal data comparisons were done to support our estimate that the male:female ratio of NT incidence was far less than the reported 412:1. In 1991, the male: female ratio of NT cases was 4.12:1. Decreasing the male: female ratio to 1:1 decreased sensitivity to a 62% estimate. Further adjusting for assumed under-reporting by governorates based on population profiles yielded a reporting sensitivity of 40%. Estimated male and female age-specific NT mortality rates from available data supported the assumption that NT mortality ratios are less than 4.12:1. This report, therefore, describes a unique, economical method to estimate the incidence of a disease assumed to be affected by gender biases in the reporting system. The method relies on two assumptions: that the true NT male:female ratio is close to 1:1 and that populations with similar demographics within a country should have similar incidence rates of NT. PMID:12002534
Choosing the forcing terms in an inexact Newton method
Energy Technology Data Exchange (ETDEWEB)
Eisenstat, S.C. [Yale Univ., New Haven, CT (United States); Walker, H.F. [Utah State Univ., Logan, UT (United States)
1994-12-31
An inexact Newton method is a generalization of Newton`s method for solving F(x) = 0, F: {Re}{sup n} {r_arrow} {Re}{sup n}, in which each step reduces the norm of the local linear model of F. At the kth iteration, the norm reduction is usefully expressed by the inexact Newton condition where x{sub k} is the current approximate solution and s{sub k} is the step. In many applications, an {eta}{sub k} is first specified, and then an S{sub k} is found for which the inexact Newton condition holds. Thus {eta}{sub k} is often called a {open_quotes}forcing term{close_quotes}. In practice, the choice of the forcing terms is usually critical to the efficiency of the method and can affect robustness as well. Here, the authors outline several promising choices, discuss theoretical support for them, and compare their performance in a Newton iterative (truncated Newton) method applied to several large-scale problems.
Stein's method and the zero bias transformation with application to simple random sampling
Goldstein, Larry; Reinert, Gesine
1997-01-01
Let $W$ be a random variable with mean zero and variance $\\sigma^2$. The distribution of a variate $W^*$, satisfying $EWf(W)=\\sigma ^2 Ef'(W^*)$ for smooth functions $f$, exists uniquely and defines the zero bias transformation on the distribution of $W$. The zero bias transformation shares many interesting properties with the well known size bias transformation for non-negative variables, but is applied to variables taking on both positive and negative values. The transformation can also be ...
Smith, Micholas Dean; Rao, J Srinivasa; Segelken, Elizabeth; Cruz, Luis
2015-12-28
In this work we examine the dynamics of an intrinsically disordered protein fragment of the amyloid β, the Aβ21-30, under seven commonly used molecular dynamics force fields (OPLS-AA, CHARMM27-CMAP, AMBER99, AMBER99SB, AMBER99SB-ILDN, AMBER03, and GROMOS53A6), and three water models (TIP3P, TIP4P, and SPC/E). We find that the tested force fields and water models have little effect on the measures of radii of gyration and solvent accessible surface area (SASA); however, secondary structure measures and intrapeptide hydrogen-bonding are significantly modified, with AMBER (99, 99SB, 99SB-ILDN, and 03) and CHARMM22/27 force-fields readily increasing helical content and the variety of intrapeptide hydrogen bonds. On the basis of a comparison between the population of helical and β structures found in experiments, our data suggest that force fields that suppress the formation of helical structure might be a better choice to model the Aβ21-30 peptide. PMID:26629886
Directory of Open Access Journals (Sweden)
Stephanie M Willerth
Full Text Available BACKGROUND: With an estimated 38 million people worldwide currently infected with human immunodeficiency virus (HIV, and an additional 4.1 million people becoming infected each year, it is important to understand how this virus mutates and develops resistance in order to design successful therapies. METHODOLOGY/PRINCIPAL FINDINGS: We report a novel experimental method for amplifying full-length HIV genomes without the use of sequence-specific primers for high throughput DNA sequencing, followed by assembly of full length viral genome sequences from the resulting large dataset. Illumina was chosen for sequencing due to its ability to provide greater coverage of the HIV genome compared to prior methods, allowing for more comprehensive characterization of the heterogeneity present in the HIV samples analyzed. Our novel amplification method in combination with Illumina sequencing was used to analyze two HIV populations: a homogenous HIV population based on the canonical NL4-3 strain and a heterogeneous viral population obtained from a HIV patient's infected T cells. In addition, the resulting sequence was analyzed using a new computational approach to obtain a consensus sequence and several metrics of diversity. SIGNIFICANCE: This study demonstrates how a lower bias amplification method in combination with next generation DNA sequencing provides in-depth, complete coverage of the HIV genome, enabling a stronger characterization of the quasispecies present in a clinically relevant HIV population as well as future study of how HIV mutates in response to a selective pressure.
A method of imaging viscoelastic parameters with acoustic radiation force
International Nuclear Information System (INIS)
Acoustic radiation force has been proposed as a method of interrogating the mechanical properties of tissue. One simple approach applies a series of focused ultrasonic pulses to generate an acoustic radiation force, then processes the echoes returned from these pulses to estimate the radiation-force-induced displacement as a function of time. This process can be repeated at a number of locations to acquire data for image formation. In previous work we have formed images of tissue stiffness by depicting the maximum displacement induced at each tissue location after a finite period of insonification. While these maximum displacement images are able to differentiate materials of disparate mechanical properties, they exploit only a fraction of the information available. In this paper we show that the time-displacement curves acquired from tissue mimicking phantoms exhibit a viscoelastic response which is accurately described by the Voigt model. We describe how the viscous and elastic parameters of this model may be determined from experimental data. Finally, we show phantom images that depict not only the maximum local displacement, but also the viscous and elastic model parameters. These images offer complementary information about the target. (author)
Numerical Method for Wave Forces Acting on Partially Perforated Caisson
Institute of Scientific and Technical Information of China (English)
姜峰; 唐晓成; 金钊; 张莉; 陈洪洲
2015-01-01
The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid–structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier–Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.
Numerical method for wave forces acting on partially perforated caisson
Jiang, Feng; Tang, Xiao-cheng; Jin, Zhao; Zhang, Li; Chen, Hong-zhou
2015-04-01
The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid-structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier-Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.
Evaluation of Bias Correction Method for Satellite-Based Rainfall Data.
Bhatti, Haris Akram; Rientjes, Tom; Haile, Alemseged Tamiru; Habib, Emad; Verhoef, Wouter
2016-01-01
With the advances in remote sensing technology, satellite-based rainfall estimates are gaining attraction in the field of hydrology, particularly in rainfall-runoff modeling. Since estimates are affected by errors correction is required. In this study, we tested the high resolution National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Centre (CPC) morphing technique (CMORPH) satellite rainfall product (CMORPH) in the Gilgel Abbey catchment, Ethiopia. CMORPH data at 8 km-30 min resolution is aggregated to daily to match in-situ observations for the period 2003-2010. Study objectives are to assess bias of the satellite estimates, to identify optimum window size for application of bias correction and to test effectiveness of bias correction. Bias correction factors are calculated for moving window (MW) sizes and for sequential windows (SW's) of 3, 5, 7, 9, …, 31 days with the aim to assess error distribution between the in-situ observations and CMORPH estimates. We tested forward, central and backward window (FW, CW and BW) schemes to assess the effect of time integration on accumulated rainfall. Accuracy of cumulative rainfall depth is assessed by Root Mean Squared Error (RMSE). To systematically correct all CMORPH estimates, station based bias factors are spatially interpolated to yield a bias factor map. Reliability of interpolation is assessed by cross validation. The uncorrected CMORPH rainfall images are multiplied by the interpolated bias map to result in bias corrected CMORPH estimates. Findings are evaluated by RMSE, correlation coefficient (r) and standard deviation (SD). Results showed existence of bias in the CMORPH rainfall. It is found that the 7 days SW approach performs best for bias correction of CMORPH rainfall. The outcome of this study showed the efficiency of our bias correction approach. PMID:27314363
Evaluation of Bias Correction Method for Satellite-Based Rainfall Data
Directory of Open Access Journals (Sweden)
Haris Akram Bhatti
2016-06-01
Full Text Available With the advances in remote sensing technology, satellite-based rainfall estimates are gaining attraction in the field of hydrology, particularly in rainfall-runoff modeling. Since estimates are affected by errors correction is required. In this study, we tested the high resolution National Oceanic and Atmospheric Administration’s (NOAA Climate Prediction Centre (CPC morphing technique (CMORPH satellite rainfall product (CMORPH in the Gilgel Abbey catchment, Ethiopia. CMORPH data at 8 km-30 min resolution is aggregated to daily to match in-situ observations for the period 2003–2010. Study objectives are to assess bias of the satellite estimates, to identify optimum window size for application of bias correction and to test effectiveness of bias correction. Bias correction factors are calculated for moving window (MW sizes and for sequential windows (SW’s of 3, 5, 7, 9, …, 31 days with the aim to assess error distribution between the in-situ observations and CMORPH estimates. We tested forward, central and backward window (FW, CW and BW schemes to assess the effect of time integration on accumulated rainfall. Accuracy of cumulative rainfall depth is assessed by Root Mean Squared Error (RMSE. To systematically correct all CMORPH estimates, station based bias factors are spatially interpolated to yield a bias factor map. Reliability of interpolation is assessed by cross validation. The uncorrected CMORPH rainfall images are multiplied by the interpolated bias map to result in bias corrected CMORPH estimates. Findings are evaluated by RMSE, correlation coefficient (r and standard deviation (SD. Results showed existence of bias in the CMORPH rainfall. It is found that the 7 days SW approach performs best for bias correction of CMORPH rainfall. The outcome of this study showed the efficiency of our bias correction approach.
Rus, David L.; Patton, Charles J.; Mueller, David K.; Crawford, Charles G.
2013-01-01
The characterization of total-nitrogen (TN) concentrations is an important component of many surface-water-quality programs. However, three widely used methods for the determination of total nitrogen—(1) derived from the alkaline-persulfate digestion of whole-water samples (TN-A); (2) calculated as the sum of total Kjeldahl nitrogen and dissolved nitrate plus nitrite (TN-K); and (3) calculated as the sum of dissolved nitrogen and particulate nitrogen (TN-C)—all include inherent limitations. A digestion process is intended to convert multiple species of nitrogen that are present in the sample into one measureable species, but this process may introduce bias. TN-A results can be negatively biased in the presence of suspended sediment, and TN-K data can be positively biased in the presence of elevated nitrate because some nitrate is reduced to ammonia and is therefore counted twice in the computation of total nitrogen. Furthermore, TN-C may not be subject to bias but is comparatively imprecise. In this study, the effects of suspended-sediment and nitrate concentrations on the performance of these TN methods were assessed using synthetic samples developed in a laboratory as well as a series of stream samples. A 2007 laboratory experiment measured TN-A and TN-K in nutrient-fortified solutions that had been mixed with varying amounts of sediment-reference materials. This experiment identified a connection between suspended sediment and negative bias in TN-A and detected positive bias in TN-K in the presence of elevated nitrate. A 2009–10 synoptic-field study used samples from 77 stream-sampling sites to confirm that these biases were present in the field samples and evaluated the precision and bias of TN methods. The precision of TN-C and TN-K depended on the precision and relative amounts of the TN-component species used in their respective TN computations. Particulate nitrogen had an average variability (as determined by the relative standard deviation) of 13
Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong
2016-05-01
Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this
Investigation of multi-junction solar cells using electrostatic force microscopy methods
Energy Technology Data Exchange (ETDEWEB)
Moczała, M., E-mail: magdalena.moczala@pwr.wroc.pl [Wrocław University of Technology, Faculty of Microsystem Electronics and Photonics, Division of Metrology of Micro- and Nanostructures, ul. Z. Janiszewskiego 11/17, 50-372 Wrocław (Poland); Sosa, N.; Topol, A. [IBM Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Gotszalk, T. [Wrocław University of Technology, Faculty of Microsystem Electronics and Photonics, Division of Metrology of Micro- and Nanostructures, ul. Z. Janiszewskiego 11/17, 50-372 Wrocław (Poland)
2014-06-01
Multi-junction III–V solar cells are designed to have a much broader absorption of the solar spectrum than Si-based or single junctions, thus yield the highest conversion. The conversion efficiency can be further scaled with sun concentration. The ability of high conversion efficiencies makes multi-junction prime candidates for fine-tuning explorations aimed at getting closer to the theoretical efficiencies. In this paper, we report on electrostatic force microscopy (EFM) measurements of the built-in potential of multi-junction III–V semiconductor-based solar cells. Kelvin probe force microscopy (KPFM) was employed to qualitatively study the width and electrical properties of individual junctions, i.e., built-in potential, activity, and thickness of the p–n junctions. In addition, the voltage drops across individual solar cell p–n junctions were measured using Kelvin probe microscopy under various operation conditions: dark; illuminated; short-circuit; and biased. We present a method which enables the measurement of a working structure, while focusing on the electrical characteristics of an individual junction by virtue of selecting the spectral range of the illumination used. We show that these pragmatic studies can provide a feedback to improve photovoltaic device design, particularly of operation under a current mismatched situation. This new analysis technique offers additional insights into behavior of the multi-junction solar cell and shows promise for further progress in this field. - Highlights: • We explore the electronic structure of III–V based high efficiency solar cells. • Qualitative study of the solar cell operation characteristics is presented. • Quantitative study of the electrostatic landscape of operational high efficiency devices is presented. • Precise identification of the epitaxially grown p–n and tunnel junctions in the multi-junction solar cell. • Influence of illumination conditions and cell biasing on each p
Investigation of multi-junction solar cells using electrostatic force microscopy methods
International Nuclear Information System (INIS)
Multi-junction III–V solar cells are designed to have a much broader absorption of the solar spectrum than Si-based or single junctions, thus yield the highest conversion. The conversion efficiency can be further scaled with sun concentration. The ability of high conversion efficiencies makes multi-junction prime candidates for fine-tuning explorations aimed at getting closer to the theoretical efficiencies. In this paper, we report on electrostatic force microscopy (EFM) measurements of the built-in potential of multi-junction III–V semiconductor-based solar cells. Kelvin probe force microscopy (KPFM) was employed to qualitatively study the width and electrical properties of individual junctions, i.e., built-in potential, activity, and thickness of the p–n junctions. In addition, the voltage drops across individual solar cell p–n junctions were measured using Kelvin probe microscopy under various operation conditions: dark; illuminated; short-circuit; and biased. We present a method which enables the measurement of a working structure, while focusing on the electrical characteristics of an individual junction by virtue of selecting the spectral range of the illumination used. We show that these pragmatic studies can provide a feedback to improve photovoltaic device design, particularly of operation under a current mismatched situation. This new analysis technique offers additional insights into behavior of the multi-junction solar cell and shows promise for further progress in this field. - Highlights: • We explore the electronic structure of III–V based high efficiency solar cells. • Qualitative study of the solar cell operation characteristics is presented. • Quantitative study of the electrostatic landscape of operational high efficiency devices is presented. • Precise identification of the epitaxially grown p–n and tunnel junctions in the multi-junction solar cell. • Influence of illumination conditions and cell biasing on each p
Gap engineering using Hellmann-Feynmann forces: method and applications
Prasai, Kiran; Biawas, Parthapratim; Drabold, D. A.
Materials with optimized band gap are needed in many specialized applications. In this talk, we demonstrate that Hellmann-Feynman forces associated with the gap states can be used to find atomic coordinates that yield desired electronic density of states. Using tight-binding models, we show that this approach may be used to arrive at electronically designed models of amorphous silicon and carbon. We provide a simple recipe to include a priori electronic information in the formation of computer models of materials, and prove that this information may have profound structural consequences. We'll briefly discuss implementation of the method in ab-initio molecular dynamics simulations and highlight the latest feats of the method ranging from modeling amorphous semi-conducting materials to understanding the structure and properties of memory materials. K. Prasai, P. Biswas, and D. A. Drabold, Scientific reports, 5 (2015).
Leyrat, Clémence; Caille, Agnès; Donner, Allan; Giraudeau, Bruno
2014-09-10
Despite randomization, selection bias may occur in cluster randomized trials. Classical multivariable regression usually allows for adjusting treatment effect estimates with unbalanced covariates. However, for binary outcomes with low incidence, such a method may fail because of separation problems. This simulation study focused on the performance of propensity score (PS)-based methods to estimate relative risks from cluster randomized trials with binary outcomes with low incidence. The results suggested that among the different approaches used (multivariable regression, direct adjustment on PS, inverse weighting on PS, and stratification on PS), only direct adjustment on the PS fully corrected the bias and moreover had the best statistical properties. PMID:24771662
Computational Catalysis Using the Artificial Force Induced Reaction Method.
Sameera, W M C; Maeda, Satoshi; Morokuma, Keiji
2016-04-19
The artificial force induced reaction (AFIR) method in the global reaction route mapping (GRRM) strategy is an automatic approach to explore all important reaction paths of complex reactions. Most traditional methods in computational catalysis require guess reaction paths. On the other hand, the AFIR approach locates local minima (LMs) and transition states (TSs) of reaction paths without a guess, and therefore finds unanticipated as well as anticipated reaction paths. The AFIR method has been applied for multicomponent organic reactions, such as the aldol reaction, Passerini reaction, Biginelli reaction, and phase-transfer catalysis. In the presence of several reactants, many equilibrium structures are possible, leading to a number of reaction pathways. The AFIR method in the GRRM strategy determines all of the important equilibrium structures and subsequent reaction paths systematically. As the AFIR search is fully automatic, exhaustive trial-and-error and guess-and-check processes by the user can be eliminated. At the same time, the AFIR search is systematic, and therefore a more accurate and comprehensive description of the reaction mechanism can be determined. The AFIR method has been used for the study of full catalytic cycles and reaction steps in transition metal catalysis, such as cobalt-catalyzed hydroformylation and iron-catalyzed carbon-carbon bond formation reactions in aqueous media. Some AFIR applications have targeted the selectivity-determining step of transition-metal-catalyzed asymmetric reactions, including stereoselective water-tolerant lanthanide Lewis acid-catalyzed Mukaiyama aldol reactions. In terms of establishing the selectivity of a reaction, systematic sampling of the transition states is critical. In this direction, AFIR is very useful for performing a systematic and automatic determination of TSs. In the presence of a comprehensive description of the transition states, the selectivity of the reaction can be calculated more accurately
Variational method for infinite nuclear matter with noncentral forces
International Nuclear Information System (INIS)
Approximate energy expressions are proposed for infinite zero-temperature nuclear matter by taking into account noncentral forces. They are explicitly expressed as functionals of spin- (isospin-) dependent radial distribution functions, tensor distribution functions and spin-orbit distribution functions, and can be used conveniently in the variational method. A notable feature of these expressions is that they automatically guarantee the necessary conditions on the spin-isospin-dependent structure functions. The Euler-Lagrange equations are derived from these energy expressions and numerically solved for neutron matter and symmetric nuclear matter. The results show that the noncentral forces bring down the total energies too much with too dense saturation densities. Since the main reason for these undesirable results seems to be the long tails of the noncentral distribution functions, an effective theory is proposed by introducing a density-dependent damping function into the noncentral potentials to suppress the long tails of the non-central distribution functions. By adjusting the value of a parameter included in the damping function, we can reproduce the saturation point (both the energy and density) of symmetric nuclear matter with the Hamada-Johnston potential. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)
Kalashnikova, A. M.; Kozub, V. I.
2016-02-01
Experimentally observed ultrafast all-optical magnetization reversal in ferrimagnetic metals and heterostructures based on antiferromagnetically coupled ferromagnetic d - and f -metallic layers relies on intricate energy and angular momentum flow between electrons, phonons, and spins. Here we treat the problem of angular momentum transfer in the course of ultrafast laser-induced dynamics in a ferrimagnetic metallic system using microscopical approach based on the system of rate equations. We show that the magnetization reversal is supported by a coupling of d and f subsystems to delocalized s or p electrons. The latter can transfer spin between the two subsystems in an incoherent way owing to the (s ;p )-(d ;f ) exchange scattering. Since the effect of the external excitation in this process is reduced to the transient heating of the mobile electron subsystem, we also discuss the possibility to trigger the magnetization reversal by applying a voltage bias pulse to antiferromagnetically coupled metallic ferromagnetic layers embedded in point contact or tunneling structures. We argue that such devices allow controlling reversal with high accuracy. We also suggest using the anomalous Hall effect to register the reversal, thus playing a role of reading probes.
Force-Directed Method in Mirror Frames for Graph Drawing
Jing Lee; Ching-Hsing Pei
2010-01-01
The most widely used algorithms for graph drawing are force-directed algorithms. We should modify a hybrid force model that is coupling a traditional spring force model and a novel repulsive force model will be proposed to solve the graph drawing problems in 2-D space. Especially, regular triangle drawing frame can be applied to binary tree drawing problems that on an important contribution to computer science. And apply circle drawing frame to normal graph drawing problems, we get satisfacto...
Novak, Janja; Jeremy D Bailoo; Melotti, Luca; Rommen, Jonas; Würbel, Hanno
2015-01-01
Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, usin...
Hashlamon, Iyad; ERBATUR, Kemalettin
2013-01-01
This paper presents a novel method for ground force sensor faults detection and faulty signal reconstruction using Virtual force Sensor (VFS) for slow walking bipeds. The design structure of the VFS consists of two steps, the total ground reaction force (GRF) and its location estimation for each leg based on the center of mass (CoM) position, the leg kinematics, and the IMU readings is carried on in the first step. In the second step, the optimal estimation of the distributed reaction forces ...
Energy Technology Data Exchange (ETDEWEB)
Ali, Fazlat; Gunji, Michiharu; Yang, Sung-Chae; Suzuki, Tsuneo; Suematsu, Hisayuki; Jiang, Weihua; Yatsui, Kiyoshi [Nagaoka Univ. of Technology, Extreme Energy-Density Research Inst., Nagaoka, Niigata (Japan)
2002-06-01
The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)
International Nuclear Information System (INIS)
The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)
Indian Academy of Sciences (India)
G Sasibhushana Rao
2007-10-01
The positional accuracy of the Global Positioning System (GPS)is limited due to several error sources.The major error is ionosphere.By augmenting the GPS,the Category I (CAT I)Precision Approach (PA)requirements can be achieved.The Space-Based Augmentation System (SBAS)in India is known as GPS Aided Geo Augmented Navigation (GAGAN).One of the prominent errors in GAGAN that limits the positional accuracy is instrumental biases.Calibration of these biases is particularly important in achieving the CAT I PA landings.In this paper,a new algorithm is proposed to estimate the instrumental biases by modelling the TEC using 4th order polynomial.The algorithm uses values corresponding to a single station for one month period and the results conﬁrm the validity of the algorithm.The experimental results indicate that the estimation precision of the satellite-plus-receiver instrumental bias is of the order of ± 0.17 nsec.The observed mean bias error is of the order − 3.638 nsec and − 4.71 nsec for satellite 1 and 31 respectively.It is found that results are consistent over the period.
A New Method of Force Control for Unknown Environments
Directory of Open Access Journals (Sweden)
Vishnu Mallapragada
2008-11-01
Full Text Available Current robotic systems are expected to interact with unknown environment where controlling the interaction forces becomes an important issue. We propose a new control technique for force control on unknown environments that tunes the force controller based on online estimation of the environment parameters. However, the proposed approach overcomes the need for precise estimation of environment parameters, which are needed in many system identification-based force control approaches. This framework uses an artificial neural network (ANN-based proportional-integral (PI-gain scheduling force controller to track the desired force by adjusting control gains such that error in parameter estimation can be accommodated. Experimental results are presented to demonstrate the efficacy of the proposed control framework. Finally, the advantages and limitations of the proposed controller are discussed.
Force-Directed Method in Mirror Frames for Graph Drawing
Directory of Open Access Journals (Sweden)
Jing Lee
2010-11-01
Full Text Available The most widely used algorithms for graph drawing are force-directed algorithms. We should modify a hybrid force model that is coupling a traditional spring force model and a novel repulsive force model will be proposed to solve the graph drawing problems in 2-D space. Especially, regular triangle drawing frame can be applied to binary tree drawing problems that on an important contribution to computer science. And apply circle drawing frame to normal graph drawing problems, we get satisfactory and aesthetic criteria graphics.
Amplified RNA degradation in T7-amplification methods results in biased microarray hybridizations
Directory of Open Access Journals (Sweden)
Ivell Richard
2003-11-01
Full Text Available Abstract Background The amplification of RNA with the T7-System is a widely used technique for obtaining increased amounts of RNA starting from limited material. The amplified RNA (aRNA can subsequently be used for microarray hybridizations, warranting sufficient signal for image analysis. We describe here an amplification-time dependent degradation of aRNA in prolonged standard T7 amplification protocols, that results in lower average size aRNA and decreased yields. Results A time-dependent degradation of amplified RNA (aRNA could be observed when using the classical "Eberwine" T7-Amplification method. When the amplification was conducted for more than 4 hours, the resulting aRNA showed a significantly smaller size distribution on gel electrophoresis and a concomitant reduction of aRNA yield. The degradation of aRNA could be correlated to the presence of the T7 RNA Polymerase in the amplification cocktail. The aRNA degradation resulted in a strong bias in microarray hybridizations with a high coefficient of variation and a significant reduction of signals of certain transcripts, that seem to be susceptible to this RNA degrading activity. The time-dependent degradation of these transcripts was verified by a real-time PCR approach. Conclusions It is important to perform amplifications not longer than 4 hours as there is a characteristic 'quality vs. yield' situation for longer amplification times. When conducting microarray hybridizations it is important not to compare results obtained with aRNA from different amplification times.
Using Category Structures to Test Iterated Learning as a Method for Identifying Inductive Biases
Griffiths, Thomas L.; Christian, Brian R.; Kalish, Michael L.
2008-01-01
Many of the problems studied in cognitive science are inductive problems, requiring people to evaluate hypotheses in the light of data. The key to solving these problems successfully is having the right inductive biases--assumptions about the world that make it possible to choose between hypotheses that are equally consistent with the observed…
Alrachid, Houssam; Lelièvre, Tony; Talhouk, Raafat
2016-05-01
We prove global existence, uniqueness and regularity of the mild, Lp and classical solution of a non-linear Fokker-Planck equation arising in an adaptive importance sampling method for molecular dynamics calculations. The non-linear term is related to a conditional expectation, and is thus non-local. The proof uses tools from the theory of semigroups of linear operators for the local existence result, and an a priori estimate based on a supersolution for the global existence result.
The Distributed Diagonal Force Decomposition Method for Parallelizing Molecular Dynamics Simulations
Boršnik, Urban; Miller, Benjamin T.; Brooks, Bernard R.; Janežič, Dušanka
2011-01-01
Parallelization is an effective way to reduce the computational time needed for molecular dynamics simulations. We describe a new parallelization method, the distributed-diagonal force decomposition method, with which we extend and improve the existing force decomposition methods. Our new method requires less data communication during molecular dynamics simulations than replicated data and current force decomposition methods, increasing the parallel efficiency. It also dynamically load-balanc...
Fourcade, Yoan; Engler, Jan O.; Rödder, Dennis; Secondi, Jean
2014-01-01
MAXENT is now a common species distribution modeling (SDM) tool used by conservation practitioners for predicting the distribution of a species from a set of records and environmental predictors. However, datasets of species occurrence used to train the model are often biased in the geographical space because of unequal sampling effort across the study area. This bias may be a source of strong inaccuracy in the resulting model and could lead to incorrect predictions. Although a nu...
Projecting future drought in Mediterranean forests: bias correction of climate models matters!
Ruffault, Julien; Martin-StPaul, Nicolas K.; Duffet, Carole; Goge, Fabien; Mouillot, Florent
2013-01-01
Global and regional climate models (GCM and RCM) are generally biased and cannot be used as forcing variables in ecological impact models without some form of prior bias correction. In this study, we investigated the influence of the bias correction method on drought projections in Mediterranean forests in southern France for the end of the twenty-first century (2071–2100). We used a water balance model with two different atmospheric climate forcings built from the same RCM simulations ...
Kappelhof, Joost W. S.
2014-01-01
"This article investigates the impact of several sources of method bias on the cross-cultural comparison of attitudes towards gender roles and family ties among non-Western minority ethnic groups. In particular, it investigates how interviewer effects, the use of an interviewer with a shared ethnic background, interview language, interviewer gender, gender matching, the presence of others during the interview and differences in socio-demographic sample composition of non-Western minority ethn...
Novak, Janja; Bailoo, Jeremy Davidson; Melotti, Luca; Rommen, Jonas; Würbel, Hanno
2015-01-01
Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive ...
Does Ignoring Multi-Destination Trips in the Travel Cost Method Cause a Systematic Downward Bias?
Kuosmanen, T.K.; Nillesen, E.E.M.; Wesseler, J.H.H.
2003-01-01
In theory, treating the multi-destination trips (MDTs) as single-destination trips (SDT) does not necessarily lead to biased results, because negative effect of price increase may be offset by the shift of the estimated demand curve. However, in our empirical application of the TCM zonal model to the valuation of the economic benefits of the Bellenden Kerr National Park in Australia we find (statistically significant) evidence that ignoring the MDTs leads to a dramatic overestimation of the c...
Does ignoring multidestination trips in the travel cost method cause a systematic bias?
Kuosmanen, Timo; Nillesen, Eleonora; Wesseler, Justus
2004-01-01
The present paper demonstrates that treating multidestination trips (MDT) as single‐destination trips does not involve any systematic upward or downward bias in consumer surplus (CS) estimates because the direct negative effect of a price increase (treating MDT as a single‐destination trip) is offset by a shift in the estimated demand curve. Still, ignoring MDT can greatly underestimate or overestimate the CS. In addition, we demonstrate that there is a sound theoretical basis for using prefe...
Method for controlling release forces in release coatings
International Nuclear Information System (INIS)
The patent deals with a process to reduce oxygen in an inert gas stream by introducing a reducing gas into the inert gas in the presence of an electron beam. This process of reducing oxygen can be used when producing radiation curable release coatings that need a desired release force. These release coatings are used in the production of pressure sensitive adhesives. 6 tabs
Nakano, Katsushi; Suzuki, Yoshihiko
1999-04-01
For inspection of high aspect ratio structures like narrow semiconductor trenches, a thin membrane probe and a new force detection method have been proposed. Instead of conventional conical and pyramidal tips, a thin silicon nitride cantilever was set up vertically, and its edge was used as a tip. The membrane probe named as twist-probe (TP) was oscillated in the twisting resonance to detect a force from both vertical and lateral directions. About 100 μm long, 0.7 μm thick TP was fabricated as a trial. Amplitude versus distance curve measurements showed that the TP has a high spacing change sensitivity between the tip and a sample in both vertical and lateral directions. A trench cross-section imaging was demonstrated successfully with a TP and the twist resonant force detection method.
Institute of Scientific and Technical Information of China (English)
刘宇航; 陈志勇; 张嵘
2013-01-01
由于微机电系统(MEMS)陀螺通常采用微加工工艺生产制造,因此总是受微加工过程带来的的各种精度缺陷影响.对于MEMS陀螺,其零位输出误差因受环境因素影响而无法保持稳定,随时间表现出漂移特性,这种特性严重限制了MEMS陀螺在更高精度应用中的可用性.该文研究了一种改善MEMS陀螺零位误差温度稳定性的方法.通过分析陀螺运动特性及主要误差源,阐明陀螺驱动力对检测方向的耦合作用是零偏误差同相分量产生并随温度漂移的主要原因之一.为抑制陀螺驱动力耦合作用,提出对陀螺检测轴施加补偿静电力的方法.温度试验结果表明:施加补偿作用后,陀螺零偏误差同相分量的温度稳定性在12～60℃范围内提高了3倍以上.%Micro electro mechanical system (MEMS) gyroscopes can be manufactured using micro-machining procedures,but they are all subject to unavoidable defects related to the fabrication processes.The zero-rate output (ZRO) of a MEMS gyroscope is known to vary with the environment which severely restricts high-precision applications.This paper presents a method to improve MEMS gyroscope thermal stability during temperature variations.Analysis of the gyro's error sources and fundamental dynamics show that the coupling of driving forces has a crucial effect on the in phase ZRO and also contributes to the instabilities of the gyro's bias.The coupling of the gyro driving forces can be suppressed by electrostatic force compensation applied to the sensing axis with temperature tests showing that the gyro bias is three times more stable after compensation for temperatures of 12 ～ 60℃.
Experimental Study on Virtual Texture Force Perception Using the JND Method
Juan Wu; Liyuan Li; Ruqiang Yan; Dejing Ni; Wei Liu
2012-01-01
This paper presents an experimental investigation on virtual texture force perception, where the Just Noticeable Difference (JND) method is used to evaluate the effects of texture spatial period and human exploratory speed on texture force perception. Two experiments have been conducted in this study. The first experiment focused on JNDs of texture force under different spatial periods (0.055‐90mm) without limiting subjects’ exploratory speeds. It was found that JNDs of texture force were bet...
International Nuclear Information System (INIS)
We demonstrate the fabrication of thin films of ionic liquid (IL), 1-butyl-3-methyl-imidazolium tetrafluoborate, by nano-inkjet printing method using an atomic force microscope (AFM) cantilever. The IL filled in a pyramidal hollow of the AFM cantilever tip was extracted from an aperture at the bottom of the hollow and deposited onto a Pt substrate when the bias voltage was applied between the cantilever and the substrate. We succeeded in fabricating IL thin films with a thickness of 4 nm. The areas and thicknesses of IL thin films were controlled by the fabrication conditions in this method, which is also useful for the investigations of nanometer-scale properties of ionic liquid.
Systems and methods of detecting force and stress using tetrapod nanocrystal
Choi, Charina L.; Koski, Kristie J.; Sivasankar, Sanjeevi; Alivisatos, A. Paul
2013-08-20
Systems and methods of detecting force on the nanoscale including methods for detecting force using a tetrapod nanocrystal by exposing the tetrapod nanocrystal to light, which produces a luminescent response by the tetrapod nanocrystal. The method continues with detecting a difference in the luminescent response by the tetrapod nanocrystal relative to a base luminescent response that indicates a force between a first and second medium or stresses or strains experienced within a material. Such systems and methods find use with biological systems to measure forces in biological events or interactions.
Force measuring valve assemblies, systems including such valve assemblies and related methods
DeWall, Kevin George; Garcia, Humberto Enrique; McKellar, Michael George
2012-04-17
Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.
Assigning a Price to Radiative Forcing: Methods, Results, and Implications
Lutz, D. A.; Howarth, R. B.
2015-12-01
Climate change mitigation frameworks have increasingly begun to include components that involve active management of the land surface. Predominantly, these programs focus on the sequestration of greenhouse gasses in vegetation and soils, generating offset credits for projects which demonstrate considerable storage. However, it is widely known that biogeophysical interactions between the land surface and the atmosphere, such as latent and sensible heat flux, albedo radiative forcing, and surface roughness, can in many cases outweigh the influence of greenhouse gas storage on global and local climate. Surface albedo, in particular, has attracted attention in the context of these frameworks because it has been shown to influence the overall climate benefits of high-latitude forest growth through tradeoffs between carbon sequestration and radiative forcing from seasonal snow cover albedo. Here we review a methodology for pricing albedo-related radiative forcing through the use of an integrated assessment model, present the results under several emissions and social preference scenarios, and describe the implications that this pricing methodology may have on forest land management in the Northeastern United States. Additionally, we investigate the consequences of projected decreased winter precipitation on the net climate benefits of snow albedo throughout the state of New Hampshire, USA.
Xu, Zhongfeng
2012-09-01
An improved dynamical downscaling method (IDD) with general circulation model (GCM) bias corrections is developed and assessed over North America. A set of regional climate simulations is performed with the Weather Research and Forecasting Model (WRF) version 3.3 embedded in the National Center for Atmospheric Research\\'s (NCAR\\'s) Community Atmosphere Model (CAM). The GCM climatological means and the amplitudes of interannual variations are adjusted based on the National Centers for Environmental Prediction (NCEP)-NCAR global reanalysis products (NNRP) before using them to drive WRF. In this study, the WRF downscaling experiments are identical except the initial and lateral boundary conditions derived from the NNRP, original GCM output, and bias-corrected GCM output, respectively. The analysis finds that the IDD greatly improves the downscaled climate in both climatological means and extreme events relative to the traditional dynamical downscaling approach (TDD). The errors of downscaled climatological mean air temperature, geopotential height, wind vector, moisture, and precipitation are greatly reduced when the GCM bias corrections are applied. In the meantime, IDD also improves the downscaled extreme events characterized by the reduced errors in 2-yr return levels of surface air temperature and precipitation. In comparison with TDD, IDD is also able to produce a more realistic probability distribution in summer daily maximum temperature over the central U.S.-Canada region as well as in summer and winter daily precipitation over the middle and eastern United States. © 2012 American Meteorological Society.
Influence of the 3D inverse dynamic method on the joint forces and moments during gait
Dumas, R; Nicol, E.; Cheze, L.
2007-01-01
The joint forces and moments are commonly used in gait analysis. They can be computed by four different 3D inverse dynamic methods proposed in the literature, either based on vectors and Euler angles, wrenches and quaternions, homogeneous matrices, or generalized coordinates and forces. In order to analyze the influence of the inverse dynamic method, the joint forces and moments were computed during gait on nine healthy subjects. A ratio was computed between the relative dispersions (due to t...
Methods for Manipulating CaF Using Optical Polychromatic Forces
Eyler, Edward E.; Galica, Scott E.; Aldridge, Leland M.
2013-06-01
We are undertaking theoretical and experimental studies of laser deceleration and cooling of molecules using coherent multi-frequency optical forces. A primary objective is to reduce radiative loss into dark states when a pure two-level cycling transition is unavailable. The optical bichromatic force (BCF) can multiply the available velocity change for a given number of radiative cycles, by employing alternating cycles of excitation and stimulated emission from opposing directions. Tests in atomic helium show that when the BCF is combined with frequency chirping, very large decelerations are achieved. We report numerical studies of variations intended to further optimize deceleration, including a 4-color version. We describe progress on experimental tests using the 531 nm B ^2Σ^+leftrightarrow X ^2Σ^+ transition in CaF. We also describe low-cost lasers and electronics developed for these experiments. Several versatile new instruments are based on 32-bit microcontrollers, interfaced to an Android tablet that provides a touch-screen graphical interface. These include a timing/ramp generator, a PZT driver, a temperature controller, and even a phase-synchronized dual 35-4000 MHz rf synthesizer that fits on a 2 1/4" × 4 3/4" board. This research is supported by the National Science Foundation. M.A. Chieda and E.E. Eyler, Phys. Rev. A 86, 053415 (2012); also Phys. Rev. A 84, 063401 (2011).
Villeneuve-Faure, C.; Boudou, L.; Makasheva, K.; Teyssedre, G.
2014-11-01
Charges injection and accumulation in the dielectric remains a critical issue, mainly because these phenomena are involved in a great number of failure mechanisms in cables or electronic components. Achieving a better understanding of the mechanisms leading to charge injection, transport and trapping under electrical stress and of the relevant interface phenomena is a high priority. The classical methods used for space charge density profile measurements have a limited spatial resolution, which prevents them being used for investigating thin dielectric layers or interface processes. Thus, techniques derived from atomic force microscopy (AFM) have been investigated more and more for this kind of application, but so far they have been limited by their lack of in-depth sensitivity. In this paper a new method for space charge probing is described, the electrostatic force distance curve (EFDC), which is based on electrostatic force measurements using AFM. A comparison with the results obtained using kelvin force microscopy (KFM) allowed us to highlight the fact that EFDC is sensitive to charges localized in the third-dimension.
Arnet, Ursina; van Drongelen, Stefan; Veeger, DirkJan H. E. J.; van der Woude, Lucas H. V.
2012-01-01
Objective: To investigate the influence of exercise conditions (speed and method to impose power) on the applied force, force effectiveness and distribution of work during handcycling. Method: Ten able-bodied men performed handcycling on a treadmill. To test the effect of speed, subjects propelled a
Amano, Ken-ich
2013-01-01
We propose iterative methods for obtaining solvation structures on a solid plate which use force distributions measured by surface force apparatus (SFA) and atomic force microscopy (AFM) as input data. Two model systems are considered here. In the model system for SFA, the same two solid plates are immersed in a solvent, and a probe tip and a solid plate are immersed in a solvent in the model system for AFM. Advantages of the iterative methods are as follows: The iterative method for SFA can obtain the solvation structure, for example, in a Lennard-Jones liquid; The iterative method for AFM can obtain the solvation structure without an input datum of solvation structure around the probe tip.
An assessment of methods for computing radiative forcing in climate models
International Nuclear Information System (INIS)
Because the radiative forcing is rarely computed separately when performing climate model simulations, several alternative methods have been developed to estimate both the instantaneous (or direct) forcing and the adjusted forcing. The adjusted forcing accounts for the radiative impact arising from the adjustment of climate variables to the instantaneous forcing, independent of any surface warming. Using climate model experiments performed for CMIP5, we find the adjusted forcing for 4 × CO2 ranges from roughly 5.5–9 W m−2 in current models. This range is shown to be consistent between different methods of estimating the adjusted forcing. Decomposition using radiative kernels and offline double-call radiative transfer calculations indicates that the spread receives a substantial contribution (roughly 50%) from intermodel differences in the instantaneous component of the radiative forcing. Moreover, nearly all of the spread in adjusted forcing can be accounted for by differences in the instantaneous forcing and stratospheric adjustment, implying that tropospheric adjustments to CO2 play only a secondary role. This suggests that differences in modeling radiative transfer are responsible for substantial differences in the projected climate response and underscores the need to archive double-call radiative transfer calculations of the instantaneous forcing as a routine diagnostic. (letter)
A Novel Analytical Solution Method for Constraint Forces of the Kinematic Pair and Its Applications
Directory of Open Access Journals (Sweden)
Changjian Zhi
2015-01-01
Full Text Available Constraint forces of the kinematic pair are the basis of the kinematics and dynamics analysis of mechanisms. Exploring the solution method for constraint forces is a hot issue in the mechanism theory fields. Based on the observation method and the theory of reciprocal screw system, the solution method of reciprocal screw system is improved and its solution procedures become easier. This method is also applied to the solution procedure of the constraint force. The specific expressions of the constraint force are represented by the reciprocal screw system of twist. The transformation formula of twist under different coordinates is given and it make the expression of the twist of kinematic pair more facility. A slider-crank mechanism and a single loop spatial RUSR mechanism are taken as examples. It confirms that this method can be used to solve the constraint force of the planar and spatial mechanism.
An inverse method was developed to integrate satellite observations of atmospheric pollutant column concentrations and direct sensitivities predicted by a regional air quality model in order to discern biases in the emissions of the pollutant precursors.
Hewstone, Miles; Rubin, Mark; Willis, Hazel
2002-01-01
This chapter reviews the extensive literature on bias in favor of in-groups at the expense of out-groups. We focus on five issues and identify areas for future research: (a) measurement and conceptual issues (especially in-group favoritism vs. out-group derogation, and explicit vs. implicit measures of bias); (b) modern theories of bias highlighting motivational explanations (social identity, optimal distinctiveness, uncertainty reduction, social dominance, terror management); (c) key moderators of bias, especially those that exacerbate bias (identification, group size, status and power, threat, positive-negative asymmetry, personality and individual differences); (d) reduction of bias (individual vs. intergroup approaches, especially models of social categorization); and (e) the link between intergroup bias and more corrosive forms of social hostility. PMID:11752497
A new PWM based control method for forced commutated cycloconverters
International Nuclear Information System (INIS)
Highlights: ► A new control method is proposed for three-phase to single-phase cycloconverters from balanced and unbalanced input voltages. ► The proposed method has no limitation on frequency conversion and is independent of the load. ► In proposed method, the low order harmonics are not generated in the input and output quantities. ► The proposed method can be easily extended to three-phase to n-phase cycloconverters. ► We demonstrate real experimental results of the power converter. - Abstract: In this paper, a new control method is proposed for three-phase to single-phase cycloconverters for synthesizing the desired output voltage from balanced and unbalanced input voltages. The theoretical analysis of the proposed control method is given for both of the conventional topologies of three-phase to single-phase cycloconverters. Using the proposed control method, the maximum output/input voltage transfer ratios are 0.5 and 1.5 for conventional cycloconverters that consist of three and six bidirectional switches, respectively. The proposed control method has no limitation on frequency conversion and is independent of the load. In other words, using the proposed control method, the three-phase to single-phase cycloconverter can operate as a generalized transformer. Using the proposed control method, the low order harmonics are not generated in the input and output quantities. As a result, the size of the required filters is decreased. The proposed control method can be easily extended to three-phase to n-phase cycloconverters based on the same principle of the operation. The simulation and experimental results verify the operation and performance of the proposed control method.
Stochastic number projection method in the pairing-force problem
Capote, R; Capote, Roberto; Gonzalez, Augusto
1999-01-01
A new stochastic number projection method is proposed. The component of the BCS wave function corresponding to the right number of particles is obtained by means of a Metropolis algorithm in which the weight functions are constructed from the single-particle occupation probability. Either standard BCS or Lipkin-Nogami probability distributions can be used, thus the method is applicable for any pairing strength. The accuracy of the method is tested in the computation of pairing energies of model and real systems.
International Nuclear Information System (INIS)
In the determination of the energy spectrum of the neutron fluxes at the surveillance and 1/4 T positions of LWRs by analyzing measured reaction rates, a calculation of these fluxes is both useful and informative in guiding the unfolding, regardless of the particular unfolding procedure used. It should thus be an important part of any unfolding procedure to be able to calculate not only the fluxes but also to estimate both the corrections to this calculation arising from various methods approximations and the uncertainties in these corrections. In at least one unfolding procedure, that utilizing a generalized least squares technique, knowledge of all uncertainties including those arising from calculational methods approximations is an essential part of the input. The particular problem addressed in this paper is the estimation of some correction factors (i.e., biases or bias factors) and their uncertainties arising from various approximations used in calculating the fluxes and reaction rates in the Pool Critical Assembly (PCA) at Oak Ridge for the 8/7 configuration. In addition, the uncertainties in the calculated fluxes and reaction rates arising as the result of uncertainties in the non-nuclear data input was investigated
Directory of Open Access Journals (Sweden)
W. Zhu
2015-02-01
Full Text Available Dynamic flux chambers (DFCs and micrometeorological (MM methods are extensively deployed for gauging air–surface Hg0 gas exchange. However, a systematic evaluation of the precision of the contemporary Hg0 flux quantification methods is not available. In this study, the uncertainty in Hg0 flux measured by relaxed eddy accumulation (REA method, aerodynamic gradient method (AGM, modified Bowen-ratio (MBR method, as well as DFC of traditional (TDFC and novel (NDFC designs is assessed using a robust data-set from two field intercomparison campaigns. The absolute precision in Hg0 concentration difference (Δ C measurements is estimated at 0.064 ng m−3 for the gradient-based MBR and AGM system. For the REA system, the parameter is Hg0 concentration (C dependent at 0.069+0.022C. 57 and 62% of the individual vertical gradient measurements were found to be significantly different from zero during the campaigns, while for the REA-technique the percentage of significant observations was lower. For the chambers, non-significant fluxes are confined to a few nighttime periods with varying ambient Hg0 concentration. Relative bias for DFC-derived fluxes is estimated to be ~ ±10%, and ~ 85% of the flux bias are within ±2 ng m−2 h−1 in absolute term. The DFC flux bias follows a diurnal cycle, which is largely dictated by temperature controls on the enclosed volume. Due to contrasting prevailing micrometeorological conditions, the relative uncertainty (median in turbulent exchange parameters differs by nearly a factor of two between the campaigns, while that in Δ C measurements is fairly stable. The estimated flux uncertainties for the triad of MM-techniques are 16–27, 12–23 and 19–31% (interquartile range for the AGM, MBR and REA method, respectively. This study indicates that flux-gradient based techniques (MBR and AGM are preferable to REA in quantifying Hg0 flux over ecosystems with low vegetation height. A limitation of all Hg0 flux
A Non-smooth Nonlinear Conjugate Gradient Method for Interactive Contact Force Problems
DEFF Research Database (Denmark)
Silcowitz, Morten; Niebe, Sarah Maria; Erleben, Kenny
Interactive rigid body simulation is important for robot simulation and virtual design. A vital part of the simulation is the computation of contact forces. This paper addresses the contact force problem, as used in interactive simulation. The contact force problem can be formulated in the form of...... a nonlinear complementarity problem (NCP), which can be solved using an iterative splitting method, such as the projected Gauss–Seidel (PGS) method. We present a novel method for solving the NCP problem by applying a Fletcher–Reeves type nonlinear nonsmooth conjugate gradient (NNCG) type method. We...
Prying Force Calculation and Design Method for T-shaped Tensile Connector with High Strength Bolt
Institute of Scientific and Technical Information of China (English)
Zhaoxin Hou; Guohong Huang; Chao Gong
2015-01-01
In order to establish the design method for T⁃shaped tensile connector with high strength bolt, the theoretical analysis is carried out. Firstly, it analyzes the performance of the connector and establishes prying force calculation model. Based on the model, prying force equation and function between bolt prying force and flange thickness is derived, and the min and max thickness requirement of flange plate under a certain tension load is then obtained. Finally, two simplified design methods of the connector are proposed, which are bolt pulling capacity method and flange plate bending capacity method.
Directory of Open Access Journals (Sweden)
MohammadReza Zare
2010-12-01
Full Text Available In permanent magnet (PM linear motor, there is force ripple, which is detrimental to positioning. This force ripple is mainly due to cogging force and mutual force ripple. These forces are affected by geometric parameters of brushless PM motor, such as width of magnet, height of magnet, shifted length of magnet pole, length and height of armature and slot width. If flux density distribution can be described by geometric parameters that are related to the force ripple and force ripple is described by the flux density distribution, the optimal design can be done by considering force ripple as cost function and geometric parameters as design variables. In this paper, at first, flux density distribution in the air gap is calculated by analytic solution of Laplace and Possion equations in the function of geometric parameters. Cogging force is obtained by integrating Maxwell stress tensor, which is described by flux density distribution, on slot face and end face of iron core of armature. Secondly, a finite element method is presented in order to compare the previous method with this method.
Biased diffusion in tubes of alternating diameter: Analytical treatment in the case of strong bias
Zitserman, Vladimir Yu.; Berezhkovskii, Alexander M.; Antipov, Anatoly E.; Makhnovskii, Yurii A.
2014-12-01
This paper is devoted to the effective transport coefficients of a particle in a tube of alternating diameter. Analytical expressions are derived for the effective mobility and diffusivity under strong bias conditions, i.e., in the limiting case where the external biasing force tends to infinity. The expressions give the transport coefficients as functions of the geometric parameters of the tube and the external force. They show that the effective diffusivity is a linear function of the square of the external force, whereas the effective mobility is independent of the force. The problem of finding effective transport coefficients in a tube of alternating diameter is too complex to be analyzed by conventional methods. Therefore, the expressions are derived in the framework of an intuition-based approach and validated by Brownian dynamics simulations. The obtained results extend a short list of available analytical expressions for the effective transport coefficients.
Precise force measurement method by a Y-shaped cavity dual-frequency laser
Institute of Scientific and Technical Information of China (English)
Guangzong Xiao; Xingwu Long; Bin Zhang; Geng Li
2011-01-01
A novel precise force measurement based on a Y-shaped cavity dual-frequency laser is proposed. The principle of force measurement with this method is analyzed, and the analytic relation expression between the input force and the change in the output beat frequency is derived. Experiments using a 632.8-nm Y-shaped cavity He-Ne dual-frequency laser are then performed; they demonstrate that the force measurement is proportional to a high degree over almost five decades of input signal range. The maximum scale factor is observed as 5.02×109 Hz/N, with beat frequency instability equivalent resolution of 10-5 N. By optimizing the optical and geometrical parameters of the laser sensor, a force measurement resolution of 10-6i N could be expected.%A novel precise force measurement based on a Y-shaped cavity dual-frequency laser is proposed.The principle of force measurement with this method is analyzed,and the analytic relation expression between the input force and the change in the output beat frequency is derived.Experiments using a 632.8-nm Y-shaped cavity He-Ne dual-frequency laser are then performed;they demonstrate that the force measurement is proportional to a high degree over almost five decades of input signal range.The maximum scale factor is observed as 5.02× 109 Hz/N,with beat frequency instability equivalent resolution of 10-5 N.By optimizing the optical and geometrical parameters of the laser sensor,a force measurement resolution of 10 -6 N could be expected.Precise measurement of force and force-related nagnitudes,such as acceleration,pressure,and mass,is an often demanded task in modern engineering and science[1-3].In recent decades,some research efforts have been intensified to utilize optical measnrement procedures for obtaining precise force measurement.
A Study of the forced Van der Pol generalized oscillator with renormalization group method
2013-01-01
In this paper the equation of forced Van der Pol generalized oscillator is examined with renormalization group method. A brief recall of the renormalization group technique is done. We have applied this method to the equation of forced Van der Pol generalized oscillator to search for its asymptotic solution and its renormalization group equation. The analysis of the numerical simulation graph is done; the method's efficiency is pointed out.
Exploration of Local Force Calculations Using the Methods of Regularized Stokeslets
Thompson, Terese
2015-01-01
We analyze the performance of the Method of Regularized Stokeslets (MRS) and the Method of Auxiliary Regularized Stokeslets (MARS) in computing the forces necessary to translate a sphere with unit velocity in Stokes ﬂow. In particular, we explore the dependence of local and global force calculations on various parameters associated with each method. The parameters we varied include the regularization parameter, the discretization of the sphere, and the spread and placement of the auxiliary St...
Methods to compute dislocation line tension energy and force in anisotropic elasticity
International Nuclear Information System (INIS)
A frame indifferent formulation of the energy and force on a dislocation in a line tension model in an anisotropic elasticity media is presented. This formulation is valid for any dislocation line direction and Burgers' vector and expresses the energy and force in terms of an integral for which no general analytical solution can be calculated. Three numerical methods are investigated to evaluate the energy and the force: direct numerical integration, spherical harmonics expansions and an interpolation table method. We analyze the convergence and computational cost of each method and compare them with a view to selecting the most appropriate for implementation in large scale dislocation dynamics codes. (paper)
Base force element method of complementary energy principle for large rotation problems
Institute of Scientific and Technical Information of China (English)
Yijiang Peng; Yinghua Liu
2009-01-01
Using the concept of the base forces, a new finite element method (base force element method, BFEM) based on the complementary energy principle is presented for accurate modeling of structures with large displacements and large rotations. First, the complementary energy of an element is described by taking the base forces as state variables, and is then separated into deformation and rotation parts for the case of large deformation. Second, the control equations of the BFEM based on the complementary energy principle are derived using the Lagrange multiplier method. Nonlinear procedure of the BFEM is then developed. Finally, several examples are analyzed to illustrate the reliability and accuracy of the BFEM.
Karatay, Durmus U; Zhang, Jie; Harrison, Jeffrey S; Ginger, David S
2016-04-25
Dynamic force spectroscopy (DFS) measurements on biomolecules typically require classifying thousands of repeated force spectra prior to data analysis. Here, we study classification of atomic force microscope-based DFS measurements using machine-learning algorithms in order to automate selection of successful force curves. Notably, we collect a data set that has a testable positive signal using photoswitch-modified DNA before and after illumination with UV (365 nm) light. We generate a feature set consisting of six properties of force-distance curves to train supervised models and use principal component analysis (PCA) for an unsupervised model. For supervised classification, we train random forest models for binary and multiclass classification of force-distance curves. Random forest models predict successful pulls with an accuracy of 94% and classify them into five classes with an accuracy of 90%. The unsupervised method using Gaussian mixture models (GMM) reaches an accuracy of approximately 80% for binary classification. PMID:27010122
Biases in approximate solution to the criticality problem and alternative Monte Carlo method
International Nuclear Information System (INIS)
The solution to the problem of criticality for the neutron transport equation using the source iteration method is addressed. In particular, the question of convergence of the iterations is examined. It is concluded that slow convergence problems will occur in cases where the optical thickness of the space region in question is large. Furthermore it is shown that in general, the final result of the iterative process is strongly affected by an insufficient accuracy of the individual iterations. To avoid these problems, a modified method of the solution is suggested. This modification is based on the results of the theory of positive operators. The criticality problem is solved by means of the Monte Carlo method by constructing special random variables so that the differences between the observed and exact results are arbitrarily small. The efficiency of the method is discussed and some numerical results are presented
2016-01-01
This book aims to cover different aspects of Bias Temperature Instability (BTI). BTI remains as an important reliability concern for CMOS transistors and circuits. Development of BTI resilient technology relies on utilizing artefact-free stress and measurement methods and suitable physics-based models for accurate determination of degradation at end-of-life, and understanding the gate insulator process impact on BTI. This book discusses different ultra-fast characterization techniques for recovery artefact free BTI measurements. It also covers different direct measurements techniques to access pre-existing and newly generated gate insulator traps responsible for BTI. The book provides a consistent physical framework for NBTI and PBTI respectively for p- and n- channel MOSFETs, consisting of trap generation and trapping. A physics-based compact model is presented to estimate measured BTI degradation in planar Si MOSFETs having differently processed SiON and HKMG gate insulators, in planar SiGe MOSFETs and also...
Recursive bias estimation for high dimensional smoothers
Energy Technology Data Exchange (ETDEWEB)
Hengartner, Nicolas W [Los Alamos National Laboratory; Matzner-lober, Eric [UHB, FRANCE; Cornillon, Pierre - Andre [INRA
2008-01-01
In multivariate nonparametric analysis, sparseness of the covariates also called curse of dimensionality, forces one to use large smoothing parameters. This leads to biased smoothers. Instead of focusing on optimally selecting the smoothing parameter, we fix it to some reasonably large value to ensure an over-smoothing of the data. The resulting smoother has a small variance but a substantial bias. In this paper, we propose to iteratively correct the bias initial estimator by an estimate of the latter obtained by smoothing the residuals. We examine in detail the convergence of the iterated procedure for classical smoothers and relate our procedure to L{sub 2}-Boosting. We apply our method to simulated and real data and show that our method compares favorably with existing procedures.
An efficient implicit direct forcing immersed boundary method for incompressible flows
International Nuclear Information System (INIS)
A novel efficient implicit direct forcing immersed boundary method for incompressible flows with complex boundaries is presented. In the previous work [1], the calculation is performed on the Cartesian grid regardless of the immersed object, with a fictitious force evaluated on the Lagrangian points to mimic the presence of the physical boundaries. However the explicit direct forcing method [1] fails to accurately impose the non-slip boundary condition on the immersed interface. In the present work, the calculation is based on the implicit treatment of the artificial force while in an effective way of system iteration. The accuracy is also improved by solving the Navier-Stokes equation with the rotational incremental pressure- correction projection method of Guermond and Shen [2]. Numerical simulations performed with the proposed method are in good agreement with those in the literature
DEFF Research Database (Denmark)
Fennema-Notestine, Christine; Ozyurt, I Burak; Clark, Camellia P;
2006-01-01
distances, and an Expectation-Maximization algorithm. Methods tended to perform better on contemporary datasets; bias correction did not significantly improve method performance. Mesial sections were most difficult for all methods. Although AD image sets were most difficult to strip, HWA and BSE were more...
Performance appraisal of Indian state police forces using ARAS method
Directory of Open Access Journals (Sweden)
Debapriyo Paul
2016-05-01
Full Text Available In the light of recent excess of reported crimes in various states and union territories (UTs of India, it becomes imperative to evaluate the police performance of different states/UTs in order to identify the poor/under-performing ones requiring immediate attention. Although, a limited amount of research work has been carried out in this area, mainly employing data envelopment analysis approach, a definitive ranking of Indian states/UTs with respect to their police performance has never been derived using any of the multi-criteria decision making (MCDM techniques. Thus, the aim of this paper is focused on evaluating and ranking of all the Indian states/UTs with respect to their performance in minimizing criminal activities while employing additive ratio assessment (ARAS method as a simplistic MCDM tool. It is revealed that Chandigarh evolves out as the best performer amongst all the 35 Indian states/UTs, while West Bengal comes out as the worst performer. A detailed analysis of the results is also carried out to identify those Indian states/UTs where substantial improvement can be brought in.
Validation of a method to predict hammer speed from cable force
Sara M. Brice; Ness, Kevin F.; Doug Rosemond
2015-01-01
Purpose: The purpose of this study was to develop and validate a method that would facilitate immediate feedback on linear hammer speed during training. Methods: Three-dimensional hammer head positional data were measured and used to calculate linear speed (calculated speed) and cable force. These data were used to develop two linear regression models (shifted and non-shifted) that would allow prediction of hammer speed from measured cable force data (predicted speed). The accuracy of the ...
Force distribution in granular media studied by an energy method based on statistical mechanics
Galindo-Torres, S A
2010-01-01
In the present letter a method to find a proper expression for the force distribution inside a granular sample in static equilibrium is proposed. The method is based in statistical mechanics and the force distribution is obtained by studying how the potential elastic energy is divided among the different contacts between grains. It is found with DEM simulations with spheres that the elastic potential energy distribution follows a Bose Einstein law from which the force distribution is deduced. The present letter open a way in which granular materials can be studied with the tools provided by statistical mechanics.
DEFF Research Database (Denmark)
Nørlykke, Simon F.; Flyvbjerg, Henrik
2010-01-01
characteristic frequency and the diffusion coefficient. We give analytical results for the weight-dependent bias for the wide class of systems whose dynamics is described by a linear (integro)differential equation with additive noise, white or colored. Examples are optical tweezers with hydrodynamic self...
An Energy Conservative Ray-Tracing Method With a Time Interpolation of the Force Field
Energy Technology Data Exchange (ETDEWEB)
Yao, Jin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-02-10
A new algorithm that constructs a continuous force field interpolated in time is proposed for resolving existing difficulties in numerical methods for ray-tracing. This new method has improved accuracy, but with the same degree of algebraic complexity compared to Kaisers method.
A method for evaluating bias in global measurements of CO{sub 2} total columns from space
Energy Technology Data Exchange (ETDEWEB)
Wunch, D.; Wennberg, P. O.; Toon, G. C.; Connor, B. J.; Fisher, B.; Osterman, G. B.; Frankenberg, C.; Mandrake, L.; O?Dell, C.; Ahonen, P.; Biraud, S. C.; Castano, R.; Cressie, N.; Crisp, D.; Deutscher, N. M.; Eldering, A.; Fisher, M. L.; Griffith, D. W.T.; Gunson, M.; Heikkinen, P.; Keppel-Aleks, G.; Kyro, E.; Lindenmaier, R.; Macatangay, R.; Mendonca, J.; Messerschmidt, J.; Miller, C. E.; Morino, I.; Notholt, J.; Oyafuso, F. A.; Rettinger, M.; Robinson, J.; Roehl, C. M.; Salawitch, R. J.; Sherlock, V.; Strong, K.; Sussmann, R.; Tanaka, T.; Thompson, D. R.; Uchino, O.; Warneke, T.; Wofsy, S. C.
2011-08-01
We describe a method of evaluating systematic errors in measurements of total column dry-air mole fractions of CO{sub 2} (X{sub CO{sub 2}} ) from space, and we illustrate the method by applying it to the Atmospheric CO{sub 2} Observations from Space retrievals of the Greenhouse Gases Observing Satellite (ACOS-GOSAT) v2.8. The approach exploits the lack of large gradients in X{sub CO{sub 2}} south of 25{degree} S to identify large-scale offsets and other biases in the ACOS-GOSAT data with several retrieval parameters and errors in instrument calibration. We demonstrate the effectiveness of the method by comparing the ACOS-GOSAT data in the Northern Hemisphere with ground truth provided by the Total Carbon Column Observing Network (TCCON). We use the correlation between free-tropospheric temperature and X{sub CO{sub 2}} in the Northern Hemisphere to define a dynamically informed coincidence criterion between the ground-based TCCON measurements and the ACOS-GOSAT measurements. We illustrate that this approach provides larger sample sizes, hence giving a more robust comparison than one that simply uses time, latitude and longitude criteria. Our results show that the agreement with the TCCON data improves after accounting for the systematic errors. A preliminary evaluation of the improved v2.9 ACOS-GOSAT data is also discussed.
International Nuclear Information System (INIS)
This paper introduces an attitude control scheme based in optimal force distribution using quadratic programming which minimizes joint energy consumption. This method shares similarities with force distribution for multifingered hands, multiple coordinated manipulators and legged walking robots. In particular, an attitude control scheme was introduced inside the force distribution problem, and successfully implemented for control of the articulated body mobile robot KR-II. This is an actual mobile robot composed of cylindrical segments linked in series by prismatic joints and has a long snake-like appearance. These prismatic joints are force controlled so that each segment's vertical motion can automatically follow the terrain irregularities. An attitude control is necessary because this system acts like a system of wheeled inverted pendulum carts connected in series, being unstable by nature. The validity and effectiveness of the proposed method is verified by computer simulation and experiments with the robot KR-II. (author)
Energy Technology Data Exchange (ETDEWEB)
Fukushima, Edwardo F.; Hirose, Shigeo [Tokyo Inst. of Tech. (Japan)
2000-05-01
This paper introduces an attitude control scheme based in optimal force distribution using quadratic programming which minimizes joint energy consumption. This method shares similarities with force distribution for multifingered hands, multiple coordinated manipulators and legged walking robots. In particular, an attitude control scheme was introduced inside the force distribution problem, and successfully implemented for control of the articulated body mobile robot KR-II. This is an actual mobile robot composed of cylindrical segments linked in series by prismatic joints and has a long snake-like appearance. These prismatic joints are force controlled so that each segment's vertical motion can automatically follow the terrain irregularities. An attitude control is necessary because this system acts like a system of wheeled inverted pendulum carts connected in series, being unstable by nature. The validity and effectiveness of the proposed method is verified by computer simulation and experiments with the robot KR-II. (author)
Applications of a novel QM/MM method incorporating a polarizable force field.
Williams, Christopher; Herbert, John
2009-03-01
In conventional QM/MM methods the MM region is modeled by a force field that uses a set of point charges to represent the electrostatics. However, recently developed force fields use multipole expansions combined with polarizable sites to to represent electrostatic interactions. A novel algorithm is presented to interface this class of force fields with a QM region by allowing the QM region and the MM region to polarize each other self-consistently. It is implemented using the QChem electronic structure code and the AMOEBA force field as implemented in the software package TINKER. The algorithm is general and can be used with a variety of QM methods including MP2 and DFT. Examples of both ground state and excited state calculations are presented, including the investigation of the effectiveness of many-body expansions in modeling the solvation of charged species and the effect of charged environments on biomolecules.
An improved method for calculating force distributions in moment-stiff timber connections
DEFF Research Database (Denmark)
Ormarsson, Sigurdur; Blond, Mette
2012-01-01
An improved method for calculating force distributions in moment-stiff multi-dowel timber connections is presented, a method based on use of three-dimensional finite element simulations of timber connections subjected to moment action. The study that was carried out aimed at determining how the...... slip modulus varies with the angle between the direction of the dowel forces and the fibres in question, as well as how the orthotropic stiffness behaviour of the wood material affects the direction and the size of the forces. It was assumed that the force distribution generated by the moment action...... taking place strives to minimize the slip rotation between the separate members of a given timber connection. The results of modified hand calculations and of the corresponding finite element calculations that were performed were found to agree rather closely, and to differ remarkably from the results of...
An improved method for calculating force distributions in moment-stiff timber connections
DEFF Research Database (Denmark)
Ormarsson, Sigurdur; Blond, Mette
2012-01-01
An improved method for calculating force distributions in moment-stiff metal dowel-type timber connections is presented, a method based on use of three-dimensional finite element simulations of timber connections subjected to moment action. The study that was carried out aimed at determining how...... the slip modulus varies with the angle between the direction of the dowel forces and the fibres in question, as well as how the orthotropic stiffness behaviour of the wood material affects the direction and the size of the forces. It was assumed that the force distribution generated by the moment...... action taking place strives to minimize the slip rotation between the separate members of a given timber connection. The results of modified hand calculations based on the finite element calculations carried out were found to differ appreciably from the results of conventional hand calculations....
Roese, Neal J; Vohs, Kathleen D
2012-09-01
Hindsight bias occurs when people feel that they "knew it all along," that is, when they believe that an event is more predictable after it becomes known than it was before it became known. Hindsight bias embodies any combination of three aspects: memory distortion, beliefs about events' objective likelihoods, or subjective beliefs about one's own prediction abilities. Hindsight bias stems from (a) cognitive inputs (people selectively recall information consistent with what they now know to be true and engage in sensemaking to impose meaning on their own knowledge), (b) metacognitive inputs (the ease with which a past outcome is understood may be misattributed to its assumed prior likelihood), and (c) motivational inputs (people have a need to see the world as orderly and predictable and to avoid being blamed for problems). Consequences of hindsight bias include myopic attention to a single causal understanding of the past (to the neglect of other reasonable explanations) as well as general overconfidence in the certainty of one's judgments. New technologies for visualizing and understanding data sets may have the unintended consequence of heightening hindsight bias, but an intervention that encourages people to consider alternative causal explanations for a given outcome can reduce hindsight bias. PMID:26168501
Finite Element Method Analysis of the Tooth Movement Induced by Orthodontic Forces
Meštrović, Senka; Šlaj, Mladen; Rajić, Petra
2003-01-01
The finite element method is a useful technique for measuring structural stress and for movement analyses. The objective of this investigation was to get a more accurate estimation of tooth movement depending on application point when a tipping orthodontic force is applied. The tree-dimensional model of un upper canine, consisting of 4,000 hexahedron elements with 2,367 nodes was obtained. Horizontal, orally directed 1N tipping orthodontic force was applied to the model on five...
The Fast Multipole Method and Point Dipole Moment Polarizable Force Fields
Coles, Jonathan P.; Masella, Michel
2014-01-01
We present an implementation of the fast multipole method for computing coulombic electrostatic and polarization forces from polarizable force-fields based on induced point dipole moments. We demonstrate the expected $O(N)$ scaling of that approach by performing single energy point calculations on hexamer protein subunits of the mature HIV-1 capsid. We also show the long time energy conservation in molecular dynamics at the nanosecond scale by performing simulations of a protein complex embed...
Schulze, T L; Jordan, R A; Hung, R W
1997-11-01
Several tick sampling methods were evaluated for ixodes scapularis Say and Amblyomma americanum (I.) in oak-dominated mixed hard-wood, pitch pine-dominated, and mixed hardwood and pine forests in coastal New Jersey. Walking surveys were more efficient for collecting I. scapularis adults than dragging by a factor of > 2:1. In contrast, drag sampling yielded nearly twice as many A. americanum adults compared with walking surveys. I. scapularis subadults were rarely collected during walking surveys. A. americanum nymphs were collected from drags approximately 3:1 over walking surveys. Twice as many A. americanum larvae were obtained from drags compared with walking surveys. All developmental stages of A. americanum responded positively to carbon dioxide. Pitfall traps and leaf litter samples collected very few ticks. Tick distribution among habitats varied significantly with the sampling method chosen, and the relative ranking of sites with respect to tick abundance varied depending on the stage of tick sampled. Failure to recognize the biases in these commonly used sampling techniques can potentially lead to incorrect conclusions that can have significant adverse public health consequences. PMID:9439115
Hart, Ross E; Willett, Kyle W; Masters, Karen L; Cardamone, Carolin; Lintott, Chris J; Mackay, Robert J; Nichol, Robert C; Rosslowe, Christopher K; Simmons, Brooke D; Smethurst, Rebecca J
2016-01-01
The majority of galaxies in the local Universe exhibit spiral structure with a variety of forms. Many galaxies possess two prominent spiral arms, some have more, while others display a many-armed flocculent appearance. Spiral arms are associated with enhanced gas content and star-formation in the disks of low-redshift galaxies, so are important in the understanding of star-formation in the local universe. As both the visual appearance of spiral structure, and the mechanisms responsible for it vary from galaxy to galaxy, a reliable method for defining spiral samples with different visual morphologies is required. In this paper, we develop a new debiasing method to reliably correct for redshift-dependent bias in Galaxy Zoo 2, and release the new set of debiased classifications. Using these, a luminosity-limited sample of ~18,000 Sloan Digital Sky Survey spiral galaxies is defined, which are then further sub-categorised by spiral arm number. In order to explore how different spiral galaxies form, the demographic...
A calibration method for optical trap force by use of electrokinetic phenomena
Institute of Scientific and Technical Information of China (English)
Youli Yu; Zhenxi Zhang; Xiaolin Zhang
2006-01-01
@@ An experimental method for calibration of optical trap force upon cells by use of electrokinetic phenomena is demonstrated.An electronkinetic sample chamber system (ESCS) is designed instead of a common sample chamber and a costly automatism stage,thus the experimental setup is simpler and cheaper.Experiments indicate that the range of the trap force measured by this method is piconewton and sub-piconewton,which makes it fit for study on non-damage interaction between light and biological particles with optical tweezers especially.Since this method is relevant to particle electric charge,by applying an alternating electric field,the new method may overcome the problem of correcting drag force and allow us to measure simultaneously optical trap stiffness and particle electric charge.
A magnetostatic force inspection method for monitoring the oscillation marks of continuous casting
International Nuclear Information System (INIS)
Based on the well-known fact that ferromagnetic materials can be significantly attracted by a permanent magnet (PM), we develop an innovative magnetostatic force inspection method to monitor the oscillating marks formed during continuous casting. A small PM produces a static magnetic field that penetrates into the ferromagnetic material slab formed via continuous casting. This magnet forms a localized magnetic sensing zone (MSZ) within the ferromagnetic material. The magnetostatic force acting on the ferromagnetic material can be expressed as the Maxwell tensor integral over the surface of the ferromagnetic material within the MSZ. This force provides local surface profile information. The reaction force of the magnetostatic force acting on the PM can be measured using a laser–cantilever system (a high force resolution method), and thus the profile features of the oscillation marks can be obtained. A measuring device with a laser–cantilever system is designed, constructed, and applied in a series of prototypes and a static experiment. A numerical model is simultaneously constructed to validate the measurement results. The differences between the actual and measured profiles are analyzed. An actual steel specimen with oscillation marks is measured using this device, and the accuracy is evaluated. In summary, the potential for the application of this method in the metallurgy industry is demonstrated. (paper)
High Precision Prediction of Rolling Force Based on Fuzzy and Nerve Method for Cold Tandem Mill
Institute of Scientific and Technical Information of China (English)
JIA Chun-yu; SHAN Xiu-ying; NIU Zhao-ping
2008-01-01
The rolling force model for cold tandem mill was put forward by using the Elman dynamic recursive network method, based on the actual measured data. Furthermore, a good assumption is put forward, which brings a full universe of discourse self-adjusting factor fuzzy control, closed-loop adjusting, based on error feedback and expertise into a rolling force prediction model, to modify prediction outputs and improve prediction precision and robustness. The simulated results indicate that the method is highly effective and the prediction precision is better than that of the traditional method. Predicted relative error is less than ±4%, so the prediction is high precise for the cold tandem mill.
A method to measure the nonlinear force caused emittance growth in a RF photoinjector
Institute of Scientific and Technical Information of China (English)
Li Zheng-Hong; Yang Zhen-Ping
2006-01-01
Based on the multi-slit method, a new method is introduced to measure the non linear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by the multi-slit method. Based on the reconstructed phase space, besides the emittance, the emittance growth from the distortion of the phase space can also be measured. The emittance growth results from the effects of nonlinear force acting on electron, which is very important for the high quality beam in a RF photoinjector.
Method for Six-Legged Robot Stepping on Obstacles by Indirect Force Estimation
Xu, Yilin; Gao, Feng; Pan, Yang; Chai, Xun
2016-04-01
Adaptive gaits for legged robots often requires force sensors installed on foot-tips, however impact, temperature or humidity can affect or even damage those sensors. Efforts have been made to realize indirect force estimation on the legged robots using leg structures based on planar mechanisms. Robot Octopus III is a six-legged robot using spatial parallel mechanism(UP-2UPS) legs. This paper proposed a novel method to realize indirect force estimation on walking robot based on a spatial parallel mechanism. The direct kinematics model and the inverse kinematics model are established. The force Jacobian matrix is derived based on the kinematics model. Thus, the indirect force estimation model is established. Then, the relation between the output torques of the three motors installed on one leg to the external force exerted on the foot tip is described. Furthermore, an adaptive tripod static gait is designed. The robot alters its leg trajectory to step on obstacles by using the proposed adaptive gait. Both the indirect force estimation model and the adaptive gait are implemented and optimized in a real time control system. An experiment is carried out to validate the indirect force estimation model. The adaptive gait is tested in another experiment. Experiment results show that the robot can successfully step on a 0.2 m-high obstacle. This paper proposes a novel method to overcome obstacles for the six-legged robot using spatial parallel mechanism legs and to avoid installing the electric force sensors in harsh environment of the robot's foot tips.
Methodes de calcul des forces aerodynamiques pour les etudes des interactions aeroservoelastiques
Biskri, Djallel Eddine
L'aeroservoelasticite est un domaine ou interagissent la structure flexible d'un avion, l'aerodynamique et la commande de vol. De son cote, la commande du vol considere l'avion comme une structure rigide et etudie l'influence du systeme de commande sur la dynamique de vol. Dans cette these, nous avons code trois nouvelles methodes d'approximation de forces aerodynamiques: Moindres carres corriges, Etat minimal corrige et Etats combines. Dans les deux premieres methodes, les erreurs d'approximation entre les forces aerodynamiques approximees par les methodes classiques et celles obtenues par les nouvelles methodes ont les memes formes analytiques que celles des forces aerodynamiques calculees par LS ou MS. Quant a la troisieme methode, celle-ci combine les formulations des forces approximees avec les methodes standards LS et MS. Les vitesses et frequences de battement et les temps d'executions calcules par les nouvelles methodes versus ceux calcules par les methodes classiques ont ete analyses.
Park, Hyunwook; Pan, Xiaomin; Lee, Changhoon; Choi, Jung-Il
2016-06-01
A novel immersed boundary (IB) method based on an implicit direct forcing (IDF) scheme is developed for incompressible viscous flows. The key idea for the present IDF method is to use a block LU decomposition technique in momentum equations with Taylor series expansion to construct the implicit IB forcing in a recurrence form, which imposes more accurate no-slip boundary conditions on the IB surface. To accelerate the IB forcing convergence during the iterative procedure, a pre-conditioner matrix is introduced in the recurrence formulation of the IB forcing. A Jacobi-type parameter is determined in the pre-conditioner matrix by minimizing the Frobenius norm of the matrix function representing the difference between the IB forcing solution matrix and the pre-conditioner matrix. In addition, the pre-conditioning parameter is restricted due to the numerical stability in the recurrence formulation. Consequently, the present pre-conditioned IDF (PIDF) enables accurate calculation of the IB forcing within a few iterations. We perform numerical simulations of two-dimensional flows around a circular cylinder and three-dimensional flows around a sphere for low and moderate Reynolds numbers. The result shows that PIDF yields a better imposition of no-slip boundary conditions on the IB surfaces for low Reynolds number with a fairly larger time step than IB methods with different direct forcing schemes due to the implicit treatment of the diffusion term for determining the IB forcing. Finally, we demonstrate the robustness of the present PIDF scheme by numerical simulations of flow around a circular array of cylinders, flows around a falling sphere, and two sedimenting spheres in gravity.
[Comparison of cell elasticity analysis methods based on atomic force microscopy indentation].
Wang, Zhe; Hao, Fengtao; Chen, Xiaohu; Yang, Zhouqi; Ding, Chong; Shang, Peng
2014-10-01
In order to investigate in greater detail the two methods based on Hertz model for analyzing force-distance curve obtained by atomic force microscopy, we acquired the force-distance curves of Hela and MCF-7 cells by atomic force microscopy (AFM) indentation in this study. After the determination of contact point, Young's modulus in different indentation depth were calculated with two analysis methods of "two point" and "slope fitting". The results showed that the Young's modulus of Hela cell was higher than that of MCF-7 cell,which is in accordance with the F-actin distribution of the two types of cell. We found that the Young's modulus of the cells was decreased with increasing indentation depth and the curve trends by "slope fitting". This indicated that the "slope fitting" method could reduce the error caused by the miscalculation of contact point. The purpose of this study was to provide a guidance for researcher to choose an appropriate method for analyzing AFM indentation force-distance curve. PMID:25764725
Shibata, Takayuki; Ito, Yasuharu; Ozawa, Tatsuya; Nagai, Moeto; Kawashima, Takahiro
2014-02-01
The introduction of biological macromolecules such as DNA, RNA, and proteins into living cells plays a crucial role in the fundamental analysis of cellular functions and mechanisms in living systems. Therefore, we have been developing an effective platform for the in vitro manipulation and analysis of biological cells at the single-cells. In this paper, we successfully demonstrated a novel intracellular delivery method of DNA into living HeLa cells via a glass micropipette based on DC-biased AC electrokinetically driven forces. We also proposed a vibration-assisted insertion method for penetrating a cell membrane to reduce cell damage. Preliminary insertion tests on homemade SICM system and FEM simulations revealed that the application of the mechanical oscillation can reduce the deformation of cells probably due to an increase in their viscous resistance. Moreover, we also found that a change in the ion current during the insertion process allows us to detect the instant when the micropipette tip penetrates the cell membrane.
Directory of Open Access Journals (Sweden)
Allahyar Geramy
2015-10-01
Full Text Available Objectives: Headgears are among the effective orthodontic appliances to achieve treatment goals. Unilateral molar distal movement is sometimes needed during an orthodontic treat- ment, which can be achieved by an asymmetric headgear. Different unilateral headgears have been introduced. The main goal of this study was to analyze the force system of uni- lateral expanded outer bow asymmetric headgears by the finite element method (FEM.Materials and Methods: Six 3D finite element models of a mesiodistal slice of the maxilla containing upper first molars, their periodontal ligaments (PDLs, cancellous bone, cortical bone, and a cervical headgear with expanded outer bow attached to maxillary first molars were designed in SolidWorks 2010 and meshed in ANSYS Workbench ver. 12.1. The mod- els were the same except for the degree of outer bow expansion. The outer bow ends were loaded with 2-Newton force. The distal driving force and the net moment were evaluated.Results: A decrease in the distalizing force in the normal side molar from 1.69 N to 1.37 N was shown by increasing the degree of unilateral expansion. At the same time, the force increased from 2.19 N to 2.49 N in the expanded side molar. A net moment increasing from 2.26 N.mm to 4.64 N.mm was also shown.Conclusion: Unilateral outer bow expansion can produce different distalizing forces in mo- lars, which increase by increasing the expansion.
A new facility to realize a nanonewton force standard based on electrostatic methods
Nesterov, V.; Mueller, M.; Frumin, L. L.; Brand, U.
2009-06-01
A new differential nanoforce facility, based on a disc-pendulum with electrostatic stiffness reduction and an electrostatic force compensation for the measurement of horizontal forces in the range below 1 µN, is presented. First measurements in air over an averaging time of 50 s show a noise level of the facility of 42 pN. The method and the results of measuring the light pressure of a red He-Ne laser with a power of 7 mW (FL = 47 pN) are presented. The force measurement uncertainty of the device is below 5%, for a force to be measured of 1 nN and a measuring duration of 50 s.
Incorporation of lubrication effects into the force-coupling method for particulate two-phase flow
International Nuclear Information System (INIS)
We investigate the performance of the force-coupling method (FCM) for particulate flow at microscales. In this work, we restrict attention to flows where we may neglect fluid inertia (Stokes flows), particle inertia and Brownian motion. The FCM performs well when distances between solid boundaries are sufficiently large, however it does not capture the local effects of viscous lubrication forces for small gap widths. To improve the results, we develop a parameterization of the lubrication forces for inclusion in the model. This is based on exact results for isolated pairs of particles and single particle-wall configurations. The correction is imposed through the addition of a lubrication barrier force on affected particles. The parameterization is tested for several cases, illustrating both the improvements possible and the limitations
The application of cubic B-spline collocation method in impact force identification
Qiao, Baijie; Chen, Xuefeng; Xue, Xiaofeng; Luo, Xinjie; Liu, Ruonan
2015-12-01
The accurate real-time characterization of impact event is vital during the life-time of a mechanical product. However, the identified impact force may seriously diverge from the real one due to the unknown noise contaminating the measured data, as well as the ill-conditioned system matrix. In this paper, a regularized cubic B-spline collocation (CBSC) method is developed for identifying the impact force time history, which overcomes the deficiency of the ill-posed problem. The cubic B-spline function by controlling the mesh size of the collocation point has the profile of a typical impact event. The unknown impact force is approximated by a set of translated cubic B-spline functions and then the original governing equation of force identification is reduced to find the coefficient of the basis function at each collocation point. Moreover, a modified regularization parameter selection criterion derived from the generalized cross validation (GCV) criterion for the truncated singular value decomposition (TSVD) is introduced for the CBSC method to determine the optimum regularization number of cubic B-spline functions. In the numerical simulation of a two degrees-of-freedom (DOF) system, the regularized CBSC method is validated under different noise levels and frequency bands of exciting forces. Finally, an impact experiment is performed on a clamped-free shell structure to confirm the performance of the regularized CBSC method. Experimental results demonstrate that the peak relative errors of impact forces based on the regularized CBSC method are below 8%, while those based on the TSVD method are approximately 30%.
Indirect (source-free) integration method. II. Self-force consistent radial fall
Ritter, P; Spallicci, A; Cordier, S
2015-01-01
We apply our method of indirect integration, described in Part I, at fourth order, to the radial fall affected by the self-force. The Mode-Sum regularisation is performed in the Regge-Wheeler gauge using the equivalence with the harmonic gauge for this orbit. We consider also the motion subjected to a self-consistent and iterative correction determined by the self-force through osculating stretches of geodesics. The convergence of the results confirms the validity of the integration method. This work complements and justifies the analysis and the results appeared in Int. J. Geom. Meth. Mod. Phys., 11, 1450090 (2014).
Yijiang Peng; Qing Guo; Zhaofeng Zhang; Yanyan Shan
2015-01-01
The four-mid-node plane model of base force element method (BFEM) on complementary energy principle is used to analyze the rock mechanics problems. The method to simulate the crack propagation using the BFEM is proposed. And the calculation method of safety factor for rock mass stability was presented for the BFEM on complementary energy principle. The numerical researches show that the results of the BFEM are consistent with the results of conventional quadrilateral isoparametric element and...
Jirschitzka, Jens; Kimmerle, Joachim; Cress, Ulrike
2016-01-01
In four studies we tested a new methodological approach to the investigation of evaluation bias. The usage of piecewise growth curve modeling allowed for investigation into the impact of people's attitudes on their persuasiveness ratings of pro- and con-arguments, measured over the whole range of the arguments' polarity from an extreme con to an extreme pro position. Moreover, this method provided the opportunity to test specific hypotheses about the course of the evaluation bias within certain polarity ranges. We conducted two field studies with users of an existing online information portal (Studies 1a and 2a) as participants, and two Internet laboratory studies with mostly student participants (Studies 1b and 2b). In each of these studies we presented pro- and con-arguments, either for the topic of MOOCs (massive open online courses, Studies 1a and 1b) or for the topic of M-learning (mobile learning, Studies 2a and 2b). Our results indicate that using piecewise growth curve models is more appropriate than simpler approaches. An important finding of our studies was an asymmetry of the evaluation bias toward pro- or con-arguments: the evaluation bias appeared over the whole polarity range of pro-arguments and increased with more and more extreme polarity. This clear-cut result pattern appeared only on the pro-argument side. For the con-arguments, in contrast, the evaluation bias did not feature such a systematic picture. PMID:26840219
Jirschitzka, Jens; Kimmerle, Joachim; Cress, Ulrike
2016-01-01
In four studies we tested a new methodological approach to the investigation of evaluation bias. The usage of piecewise growth curve modeling allowed for investigation into the impact of people’s attitudes on their persuasiveness ratings of pro- and con-arguments, measured over the whole range of the arguments’ polarity from an extreme con to an extreme pro position. Moreover, this method provided the opportunity to test specific hypotheses about the course of the evaluation bias within certain polarity ranges. We conducted two field studies with users of an existing online information portal (Studies 1a and 2a) as participants, and two Internet laboratory studies with mostly student participants (Studies 1b and 2b). In each of these studies we presented pro- and con-arguments, either for the topic of MOOCs (massive open online courses, Studies 1a and 1b) or for the topic of M-learning (mobile learning, Studies 2a and 2b). Our results indicate that using piecewise growth curve models is more appropriate than simpler approaches. An important finding of our studies was an asymmetry of the evaluation bias toward pro- or con-arguments: the evaluation bias appeared over the whole polarity range of pro-arguments and increased with more and more extreme polarity. This clear-cut result pattern appeared only on the pro-argument side. For the con-arguments, in contrast, the evaluation bias did not feature such a systematic picture. PMID:26840219
Directory of Open Access Journals (Sweden)
Jens Jirschitzka
Full Text Available In four studies we tested a new methodological approach to the investigation of evaluation bias. The usage of piecewise growth curve modeling allowed for investigation into the impact of people's attitudes on their persuasiveness ratings of pro- and con-arguments, measured over the whole range of the arguments' polarity from an extreme con to an extreme pro position. Moreover, this method provided the opportunity to test specific hypotheses about the course of the evaluation bias within certain polarity ranges. We conducted two field studies with users of an existing online information portal (Studies 1a and 2a as participants, and two Internet laboratory studies with mostly student participants (Studies 1b and 2b. In each of these studies we presented pro- and con-arguments, either for the topic of MOOCs (massive open online courses, Studies 1a and 1b or for the topic of M-learning (mobile learning, Studies 2a and 2b. Our results indicate that using piecewise growth curve models is more appropriate than simpler approaches. An important finding of our studies was an asymmetry of the evaluation bias toward pro- or con-arguments: the evaluation bias appeared over the whole polarity range of pro-arguments and increased with more and more extreme polarity. This clear-cut result pattern appeared only on the pro-argument side. For the con-arguments, in contrast, the evaluation bias did not feature such a systematic picture.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The vast majority of tool condition monitoring systems use the motor current instead of the cutting force as the predictor signal. The measured motor current signal is time-dependant and instable. It is difficult to detect the cutting force token signal from such motor current signal. This paper presents a method that uses the wavelet transforms to reconstruct the cutting force token signal from the current signal based on the time frequency analysis of the cutting force signal. The result of the cutting force measurement experiment shows that the proposed reconstruct method could be used to analyze the spindle current and monitor the time-varying cutting force.
Hamad, Ibrahim Abou; Novotny, Mark A; Rikvold, Per Arne
2007-01-01
We propose a new, cyclic-voltammetry based experimental technique that can not only differentiate between discontinuous and continuous phase transitions in an adsorbate layer, but also quite accurately recover equilibrium behavior from dynamic analysis of systems with a continuous phase transition. The Electrochemical first-order reversal curve (EC-FORC) diagram for a discontinuous phase transition (nucleation and growth), such as occurs in underpotential deposition, is characterized by a negative region, while such a region does not exist for a continuous phase transition, such as occurs in the electrosorption of Br on Ag(100). Moreover, for systems with a continuous phase transition, the minima of the individual EC-FORCs trace the equilibrium curve, even at very high scan rates. Since obtaining experimental data for the EC-FORC method would require only a simple reprogramming of the potentiostat used in conventional cyclic-voltammetry experiments, we believe that this method has significant potential for ea...
Finite Element Based Stress Analysis of Seat Belt Using Integrated Force Method
Directory of Open Access Journals (Sweden)
Anjali Kale
2014-06-01
Full Text Available Integrated force method (IFM has been developed for solving various continuum mechanics problems, where all the internal forces are taken as independent variables. The system equilibrium equations (EE's are mathematically concatenated with the MATLAB based compatibility conditions (CC's to form the global set of equations. This paper explains the solution strategy of prototype seat-belt component using integrated force method. Actual seat belt component is taken here to verify IFM based FE element are readily used which is named as REC_5F_8D and REC_13F_16D where 5F and 13F reflects number of internal unknowns and 8D and 16D are number of total displacements respectively. The results for “Von Mises Stress” and Maximum Displacement using IFM based formulation and compared with ANSYS.
Finite Element Method Based Modeling for Prediction of Cutting Forces in Micro-end Milling
Pratap, Tej; Patra, Karali
2016-04-01
Micro-end milling is one of the widely used processes for producing micro features/components in micro-fluidic systems, biomedical applications, aerospace applications, electronics and many more fields. However in these applications, the forces generated in the micro-end milling process can cause tool vibration, process instability and even cause tool breakage if not minimized. Therefore, an accurate prediction of cutting forces in micro-end milling is essential. In this work, a finite element method based model is developed using ABAQUS/Explicit 6.12 software for prediction of cutting forces in micro-end milling with due consideration of tool edge radius effect, thermo-mechanical properties and failure parameters of the workpiece material including friction behaviour at tool-chip interface. Experiments have been performed for manufacturing of microchannels on copper plate using 500 µm diameter tungsten carbide micro-end mill and cutting forces are acquired through a dynamometer. Predicted cutting forces in feed and cross feed directions are compared with experimental results and are found to be in good agreements. Results also show that FEM based simulations can be applied to analyze size effects of specific cutting forces in micro-end milling process.
Directory of Open Access Journals (Sweden)
Yung-Chou Kao
2015-10-01
Full Text Available In this paper, the cutting force calculation of ball-end mill processing was modeled mathematically. All derivations of cutting forces were directly based on the tangential, radial, and axial cutting force components. In the developed mathematical model of cutting forces, the relationship of average cutting force and the feed per flute was characterized as a linear function. The cutting force coefficient model was formulated by a function of average cutting force and other parameters such as cutter geometry, cutting conditions, and so on. An experimental method was proposed based on the stable milling condition to estimate the cutting force coefficients for ball-end mill. This method could be applied for each pair of tool and workpiece. The developed cutting force model has been successfully verified experimentally with very promising results.
First priciples simulations of a bias-dependent electrochemical cell
Pedroza, Luana S; Rocha, Alexandre Reily; Fernández-Serra, Marivi
2016-01-01
Understanding the local structure of liquid water at the interfaces of metallic electrodes is a key problem in aqueous-based electrochemistry. Notably the system is under an external potential bias, which makes the task of simulating this setup difficult. To correctly compute the effect of an external bias potential applied to electrodes, we combine density functional theory and non-equilibrium Green's functions methods. Our method now allows to explicitly consider an external applied bias, in direct correspondence to the experiments. In this work, we apply this methodology to study the electronic properties and atomic forces of one water molecule at the interface of gold electrodes. We find that, as expected, the water molecule is sensitive to the sign and magnitude of the applied bias.
International Nuclear Information System (INIS)
We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increase output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope
Energy Technology Data Exchange (ETDEWEB)
Guo, Ying; Lu, Qingyou, E-mail: qxl@ustc.edu.cn [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hou, Yubin [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China)
2014-05-15
We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increase output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope.
DEFF Research Database (Denmark)
Chen, Jingzhe; Thygesen, Kristian S.; Jacobsen, Karsten W.
2012-01-01
We present an efficient implementation of a nonequilibrium Green's function method for self-consistent calculations of electron transport and forces in nanostructured materials. The electronic structure is described at the level of density functional theory using the projector augmented wave meth...
The Australian Defence Force Mental Health Prevalence and Wellbeing Study: design and methods.
Hooff, M.V.; McFarlane, A.C.; Davies, C.E.; Searle, A.K.; Fairweather-Schmidt, A.K.; Verhagen, A.F.; Benassi, H.; Hodson, S.E.
2014-01-01
BACKGROUND: The Australian Defence Force (ADF) Mental Health Prevalence and Wellbeing Study (MHPWS) is the first study of mental disorder prevalence in an entire military population. OBJECTIVE: The MHPWS aims to establish mental disorder prevalence, refine current ADF mental health screening methods
Kaljevic, Igor; Patnaik, Surya N.; Hopkins, Dale A.
1996-01-01
The Integrated Force Method has been developed in recent years for the analysis of structural mechanics problems. This method treats all independent internal forces as unknown variables that can be calculated by simultaneously imposing equations of equilibrium and compatibility conditions. In this paper a finite element library for analyzing two-dimensional problems by the Integrated Force Method is presented. Triangular- and quadrilateral-shaped elements capable of modeling arbitrary domain configurations are presented. The element equilibrium and flexibility matrices are derived by discretizing the expressions for potential and complementary energies, respectively. The displacement and stress fields within the finite elements are independently approximated. The displacement field is interpolated as it is in the standard displacement method, and the stress field is approximated by using complete polynomials of the correct order. A procedure that uses the definitions of stress components in terms of an Airy stress function is developed to derive the stress interpolation polynomials. Such derived stress fields identically satisfy the equations of equilibrium. Moreover, the resulting element matrices are insensitive to the orientation of local coordinate systems. A method is devised to calculate the number of rigid body modes, and the present elements are shown to be free of spurious zero-energy modes. A number of example problems are solved by using the present library, and the results are compared with corresponding analytical solutions and with results from the standard displacement finite element method. The Integrated Force Method not only gives results that agree well with analytical and displacement method results but also outperforms the displacement method in stress calculations.
Lubow, Bruce C; Ransom, Jason I
2016-01-01
Reliably estimating wildlife abundance is fundamental to effective management. Aerial surveys are one of the only spatially robust tools for estimating large mammal populations, but statistical sampling methods are required to address detection biases that affect accuracy and precision of the estimates. Although various methods for correcting aerial survey bias are employed on large mammal species around the world, these have rarely been rigorously validated. Several populations of feral horses (Equus caballus) in the western United States have been intensively studied, resulting in identification of all unique individuals. This provided a rare opportunity to test aerial survey bias correction on populations of known abundance. We hypothesized that a hybrid method combining simultaneous double-observer and sightability bias correction techniques would accurately estimate abundance. We validated this integrated technique on populations of known size and also on a pair of surveys before and after a known number was removed. Our analysis identified several covariates across the surveys that explained and corrected biases in the estimates. All six tests on known populations produced estimates with deviations from the known value ranging from -8.5% to +13.7% and population between the surveys that was significantly larger than the known reduction. Although the deviation between was only 9.1%, the precision estimate (CV = 1.6%) may have been artificially low. It was apparent that use of a helicopter in those surveys perturbed the horses, introducing detection error and heterogeneity in a manner that could not be corrected by our statistical models. Our results validate the hybrid method, highlight its potentially broad applicability, identify some limitations, and provide insight and guidance for improving survey designs. PMID:27139732
2016-01-01
Reliably estimating wildlife abundance is fundamental to effective management. Aerial surveys are one of the only spatially robust tools for estimating large mammal populations, but statistical sampling methods are required to address detection biases that affect accuracy and precision of the estimates. Although various methods for correcting aerial survey bias are employed on large mammal species around the world, these have rarely been rigorously validated. Several populations of feral horses (Equus caballus) in the western United States have been intensively studied, resulting in identification of all unique individuals. This provided a rare opportunity to test aerial survey bias correction on populations of known abundance. We hypothesized that a hybrid method combining simultaneous double-observer and sightability bias correction techniques would accurately estimate abundance. We validated this integrated technique on populations of known size and also on a pair of surveys before and after a known number was removed. Our analysis identified several covariates across the surveys that explained and corrected biases in the estimates. All six tests on known populations produced estimates with deviations from the known value ranging from -8.5% to +13.7% and <0.7 standard errors. Precision varied widely, from 6.1% CV to 25.0% CV. In contrast, the pair of surveys conducted around a known management removal produced an estimated change in population between the surveys that was significantly larger than the known reduction. Although the deviation between was only 9.1%, the precision estimate (CV = 1.6%) may have been artificially low. It was apparent that use of a helicopter in those surveys perturbed the horses, introducing detection error and heterogeneity in a manner that could not be corrected by our statistical models. Our results validate the hybrid method, highlight its potentially broad applicability, identify some limitations, and provide insight and guidance
Inertia Force Identification of Cantilever under Moving-Mass by Inverse Method
Directory of Open Access Journals (Sweden)
Qiang Chen
2012-12-01
Full Text Available In this paper, a recursive inverse method is applied to solve the identification problem of inertia force between the cantilever and moving mass. The recursive inverse method consists of two parts: Kalman filter and recursive least-square algorithm. The basic Euler-Bernoulli beam model is introduced. Then, the differential equations and the state space model of the modal responses and the inertia force can be obtained. Finally, the recursive inverse method, which is based on the discretized state function of the system, is adapted. The identification results show that the recursive inverse method is suitable to be adapted in this problem. Some characteristics of the identification results are discussed and some further conclusions are reached.
A nondestructive calibration method for maximizing the range and accuracy of AFM force measurement
International Nuclear Information System (INIS)
In this paper, a nondestructive method for the normal and lateral sensitivity calibrations of the optical lever in atomic force microscope (AFM) is presented. The practical application of this method in a dual-probe AFM is discussed in detail. To calibrate the conversion factors between photodiode responses and probe's deflection angles accurately without applying forces to the probe, a two-degrees-of-freedom flexure-hinge-based calibration device (FHCD) is developed. The device, which mainly consists of two mutually perpendicular flexure-hinge levers that share the same rotational center, serves as a switching mechanism for precise translation-to-rotation conversions both in the normal and lateral directions. During the calibration, a probe is attached to the FHCD at the meeting of the rotational axes of two levers. The FHCD is mounted on an AFM sample platform. The probe in this method acts as a mirror to be normally and laterally tilted at nanoscale angles to deflect the reflected laser beam by twisting the corresponding flexure-hinge levers, rather than the force-inducing probe deflection in traditional AFM calibration methods. With this method, the nondestructive calibration of the local and full-range sensitivities of the optical levers can be completed without destroying the probe tip or modifying the actual system setup of an AFM. Moreover, the nonlinearities of the optical levers are accurately compensated. Experimental results show that the linear ranges (with a deviation of 5% in the full range) of the force measurement are extended to 3.6 and 4.5 times in the normal and lateral directions, respectively, increasing to over 90% of the full range of the force measurement. (paper)
Directory of Open Access Journals (Sweden)
Daniel Gandyra
2015-01-01
Full Text Available We report a novel, practical technique for the concerted, simultaneous determination of both the adhesion force of a small structure or structural unit (e.g., an individual filament, hair, micromechanical component or microsensor to a liquid and its elastic properties. The method involves the creation and development of a liquid meniscus upon touching a liquid surface with the structure, and the subsequent disruption of this liquid meniscus upon removal. The evaluation of the meniscus shape immediately before snap-off of the meniscus allows the quantitative determination of the liquid adhesion force. Concurrently, by measuring and evaluating the deformation of the structure under investigation, its elastic properties can be determined. The sensitivity of the method is remarkably high, practically limited by the resolution of the camera capturing the process. Adhesion forces down to 10 µN and spring constants up to 2 N/m were measured. Three exemplary applications of this method are demonstrated: (1 determination of the water adhesion force and the elasticity of individual hairs (trichomes of the floating fern Salvinia molesta. (2 The investigation of human head hairs both with and without functional surface coatings (a topic of high relevance in the field of hair cosmetics was performed. The method also resulted in the measurement of an elastic modulus (Young’s modulus for individual hairs of 3.0 × 105 N/cm2, which is within the typical range known for human hair. (3 Finally, the accuracy and validity of the capillary adhesion technique was proven by examining calibrated atomic force microscopy cantilevers, reproducing the spring constants calibrated using other methods.
PRESSURE FORCE CONTROL FOR FABRICATION OF PLASTIC MICROFLUIDIC CHIPS WITH HOT EMBOSSING METHOD
Institute of Scientific and Technical Information of China (English)
LIU Chong; LIAO Junfeng; WANG Xiaodong; WANG Liding
2007-01-01
A pressure force control system for hot embossing of microfluidic chips is designed with a moment motor and a ball bearing lead screw. Based on the numeric PID technique, the algorithm of pulsant integral accelerated PID control is presented and the negative effects of nonlinearity from friction, clearance and saturation are eliminated. In order to improve the quick-response characteristic, independent thread technique is adopted. The method of pressure force control based on pulsant integral accelerated PID control and independent thread technique is applied with satisfactory control performance.
The Australian Defence Force Mental Health Prevalence and Wellbeing Study: design and methods
Van Hooff, Miranda; McFarlane, Alexander C; Christopher E. Davies; Searle, Amelia K.; Fairweather-Schmidt, A Kate; Verhagen, Alan; Benassi, Helen; Stephanie E Hodson
2014-01-01
Background: The Australian Defence Force (ADF) Mental Health Prevalence and Wellbeing Study (MHPWS) is the first study of mental disorder prevalence in an entire military population.Objective: The MHPWS aims to establish mental disorder prevalence, refine current ADF mental health screening methods, and identify specific occupational factors that influence mental health. This paper describes the design, sampling strategies, and methodology used in this study.Method: At Phase 1, approximately ...
A direct micropipette-based calibration method for atomic force microscope cantilevers
Liu, Baoyu; Yu, Yan; Yao, Da-Kang; Shao, Jin-Yu
2009-01-01
In this report, we describe a direct method for calibrating atomic force microscope (AFM) cantilevers with the micropipette aspiration technique (MAT). A closely fitting polystyrene bead inside a micropipette is driven by precisely controlled hydrostatic pressures to apply known loads on the sharp tip of AFM cantilevers, thus providing a calibration at the most functionally relevant position. The new method is capable of calibrating cantilevers with spring constants ranging from 0.01 to hundr...
Spatial uncertainty in bias corrected climate change projections and hydrogeological impacts
DEFF Research Database (Denmark)
Seaby, Lauren Paige; Refsgaard, Jens Christian; Sonnenborg, Torben;
2015-01-01
The question of which climate model bias correction methods and spatial scales for correction are optimal for both projecting future hydrological changes as well as removing initial model bias has so far received little attention. For 11 climate models (CMs), or GCM/RCM – Global/Regional Climate...... Model pairing, this paper analyses the relationship between complexity and robustness of three distribution-based scaling (DBS) bias correction methods applied to daily precipitation at various spatial scales. Hydrological simulations are forced by CM inputs to assess the spatial uncertainty of...... signals. The magnitude of spatial bias seen in precipitation inputs does not necessarily correspond to the magnitude of biases seen in hydrological outputs. Variables that integrate basin responses over time and space are more sensitive to mean spatial biases and less so on extremes. Hydrological...
Evaluation of drag force on a nonuniform particle distribution with a meshless method
Institute of Scientific and Technical Information of China (English)
Xi Wang; Changfu You
2011-01-01
A meshless Element-Free Galerkin (EFG) method was used to directly simulate the fluidization process in two dimensions. The drag force on particles was obtained by integrating the stress and shear forces on the particle surfaces. The results show that meshless methods are capable of dealing with real particle collisions, thus are superior to most mesh-based methods in reflecting the fluidization process with frequent particle collisions and suitable void fractions. Particle distribution greatly influences the drag coefficients even for the same voidage, that is, there are large differences in the average drag coefficients between nonuniform and uniform particle distributions. Different compacting directions also have different regularities, so conventional formulas such as ‘Wen and Yu' and ‘Felice' models have some deviations in such nonuniform distributions. To evaluate the influence of the nonuniformity, the drag force in multiple particle systems was simulated by using nonuniformity coefficients, CVX and Cw, to quantitatively describe the nonuniform distribution in different directions. Drag force during fluidization can be successfully evaluated by the use of Cvx alone.
A novel AFM based method for force measurements between individual hair strands
International Nuclear Information System (INIS)
Interactions between hairs and other natural fibers are of broad interest for both applications and fundamental understanding of biological interfaces. We present a novel method, that allows force measurements between individual hair strands. Hair fragments can be laser-cut without altering their surface chemistry. Subsequently, they are glued onto Atomic force microscopy (AFM) cantilevers. This allows carrying out measurements between the hair fragment and surface immobilized hair in a well-defined crossed-cylinder geometry. Both force-distance and friction measurements are feasible. Measurements in air with controlled humidity and in aqueous environment show clear differences which can be explained by the dominating role of capillary interactions in air. Friction is found to be anisotropic, reflecting the fine structure of hair cuticula. While the investigations are focused on the particular example of human hair, we expect that the approach can be extended to other animal/plant fibers and thus offers perspectives for broad spectrum systems.
A novel AFM based method for force measurements between individual hair strands
Energy Technology Data Exchange (ETDEWEB)
Max, Eva; Haefner, Wolfgang [Physical Chemistry II, University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth (Germany); Wilco Bartels, Frank [Polymer Physics, Global PU Specialties Research, BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemfoerde (Germany); Sugiharto, Albert [Polymer Physics and Analytics, G201, 67056 Ludwigshafen (Germany); Wood, Claudia [Care Chemicals and Formulators, Personal Care Ingredients, New Business and Application Development, BASF SE, E-EMV/GP - H201, 67056 Ludwigshafen (Germany); Fery, Andreas, E-mail: andreas.fery@uni-bayreuth.de [Physical Chemistry II, University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth (Germany)
2010-03-15
Interactions between hairs and other natural fibers are of broad interest for both applications and fundamental understanding of biological interfaces. We present a novel method, that allows force measurements between individual hair strands. Hair fragments can be laser-cut without altering their surface chemistry. Subsequently, they are glued onto Atomic force microscopy (AFM) cantilevers. This allows carrying out measurements between the hair fragment and surface immobilized hair in a well-defined crossed-cylinder geometry. Both force-distance and friction measurements are feasible. Measurements in air with controlled humidity and in aqueous environment show clear differences which can be explained by the dominating role of capillary interactions in air. Friction is found to be anisotropic, reflecting the fine structure of hair cuticula. While the investigations are focused on the particular example of human hair, we expect that the approach can be extended to other animal/plant fibers and thus offers perspectives for broad spectrum systems.
Validation of engineering methods for predicting hypersonic vehicle controls forces and moments
Maughmer, M.; Straussfogel, D.; Long, L.; Ozoroski, L.
1991-01-01
This work examines the ability of the aerodynamic analysis methods contained in an industry standard conceptual design code, the Aerodynamic Preliminary Analysis System (APAS II), to estimate the forces and moments generated through control surface deflections from low subsonic to high hypersonic speeds. Predicted control forces and moments generated by various control effectors are compared with previously published wind-tunnel and flight-test data for three vehicles: the North American X-15, a hypersonic research airplane concept, and the Space Shuttle Orbiter. Qualitative summaries of the results are given for each force and moment coefficient and each control derivative in the various speed ranges. Results show that all predictions of longitudinal stability and control derivatives are acceptable for use at the conceptual design stage.
A method of improving the dynamic response of 3D force/torque sensors
Osypiuk, Rafał; Piskorowski, Jacek; Kubus, Daniel
2016-02-01
In the paper attention is drawn to adverse dynamic properties of filters implemented in commercial measurement systems, force/torque sensors, which are increasingly used in industrial robotics. To remedy the problem, it has been proposed to employ a time-variant filter with appropriately modulated parameters, owing to which it is possible to suppress the amplitude of the transient response and, at the same time, to increase the pulsation of damped oscillations; this results in the improvement of dynamic properties in terms of reducing the duration of transients. This property plays a key role in force control and in the fundamental problem of the robot establishing contact with rigid environment. The parametric filters have been verified experimentally and compared with filters available for force/torque sensors manufactured by JR3. The obtained results clearly indicate the advantages of the proposed solution, which may be an interesting alternative to the classic methods of filtration.
International Nuclear Information System (INIS)
Electrostatic force microscopy (EFM) is a special design of non-contact atomic force microscopy used for detecting electrostatic interactions between the probe tip and the sample. Its resolution is limited by the finite probe size and the long-range characteristics of electrostatic forces. Therefore, quantitative analysis is crucial to understanding the relationship between the actual local surface potential distribution and the quantities obtained from EFM measurements. To study EFM measurements on bimetallic samples with surface potential inhomogeneities as a special case, we have simulated such measurements using the boundary element method and calculated the force component and force gradient component that would be measured by amplitude modulation (AM) EFM and frequency modulation (FM) EFM, respectively. Such analyses have been performed for inhomogeneities of various shapes and sizes, for different tip-sample separations and tip geometries, for different applied voltages, and for different media (e.g., vacuum or water) in which the experiment is performed. For a sample with a surface potential discontinuity, the FM-EFM resolution expression agrees with the literature; however, the simulation for AM-EFM suggests the existence of an optimal tip radius of curvature in terms of resolution. On the other hand, for samples with strip- and disk-shaped surface potential inhomogeneities, we have obtained quantitative expressions for the detectability size requirements as a function of experimental conditions for both AM- and FM-EFMs, which suggest that a larger tip radius of curvature is moderately favored for detecting the presence of such inhomogeneities
Czech Academy of Sciences Publication Activity Database
Szabó-Takács, Beáta; Farda, Aleš; Štěpánek, Petr; Skalák, Petr; Zahradníček, Pavel
Volume 1. 1. Brno: Global Change Research Centre, Academy of Sciences of the Czech Republic, v. v. i, 2015 - (Urban, O.; Klem, K.), s. 38-44 ISBN 978-80-87902-14-1 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : climate projection * ENSEMBLES * bias correction * temperature * precipitation Subject RIV: DG - Athmosphere Sciences, Meteorology
A fast high-order method to calculate wakefield forces in an electron beam
Energy Technology Data Exchange (ETDEWEB)
Qiang, Ji; Mitchell, Chad; Ryne, Robert D.
2012-03-22
In this paper we report on a high-order fast method to numerically calculate wakefield forces in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an O(Nlog(N)) computational cost, where N is the number of grid points. Using the Simpson quadrature rule with an accuracy of O(h4), where h is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield force. I. INTRODUCTION
A fast high-order method to calculate wakefield forces in an electron beam
Qiang, Ji; Ryne, Robert D
2012-01-01
In this paper we report on a high-order fast method to numerically calculate wakefield forces in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an $O(Nlog(N))$ computational cost, where $N$ is the number of grid points. Using the Simpson quadrature rule with an accuracy of $O(h^4)$, where $h$ is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield force.
Knowledge-Based Trajectory Error Pattern Method Applied to an Active Force Control Scheme
Directory of Open Access Journals (Sweden)
Endra Pitowarno, Musa Mailah, Hishamuddin Jamaluddin
2012-08-01
Full Text Available The active force control (AFC method is known as a robust control scheme that dramatically enhances the performance of a robot arm particularly in compensating the disturbance effects. The main task of the AFC method is to estimate the inertia matrix in the feedback loop to provide the correct (motor torque required to cancel out these disturbances. Several intelligent control schemes have already been introduced to enhance the estimation methods of acquiring the inertia matrix such as those using neural network, iterative learning and fuzzy logic. In this paper, we propose an alternative scheme called Knowledge-Based Trajectory Error Pattern Method (KBTEPM to suppress the trajectory track error of the AFC scheme. The knowledge is developed from the trajectory track error characteristic based on the previous experimental results of the crude approximation method. It produces a unique, new and desirable error pattern when a trajectory command is forced. An experimental study was performed using simulation work on the AFC scheme with KBTEPM applied to a two-planar manipulator in which a set of rule-based algorithm is derived. A number of previous AFC schemes are also reviewed as benchmark. The simulation results show that the AFC-KBTEPM scheme successfully reduces the trajectory track error significantly even in the presence of the introduced disturbances.Key Words: Active force control, estimated inertia matrix, robot arm, trajectory error pattern, knowledge-based.
A piecewise-integration method for simulating the influence of external forcing on climate
Institute of Scientific and Technical Information of China (English)
Zhifu Zhang; Chongjian Qiu; Chenghai Wang
2008-01-01
Climate drift occurs in most general circulation models (GCMs) as a result of incomplete physical and numerical representation of the complex climate system,which may cause large uncertainty in sensitivity experiments evaluating climate response to changes in external forcing.To solve this problem,we propose a piecewise-integration method to reduce the systematic error in climate sensitivity studies.The observations are firstly assimilated into a numerical model by using the dynamic relaxation technique to relax to the current state of atmosphere,and then the assimilated fields are continuously used to reinitialize the simulation to reduce the error of climate simulation.When the numerical model is integrated with changed external forcing,the results can be split into two parts,background and perturbation fields,and the background is the state before the external forcing is changed.The piecewise-integration method is used to continuously reinitialize the model with the assimilated field,instead of the background.Therefore,the simulation error of the model with the external forcing can be reduced.In this way,the accuracy of climate sensitivity experiments is greatly improved.Tests with a simple low-order spectral model show that this approach can significantly reduce the uncertainty of climate sensitivity experiments.
New method of space debris cleaning based on light negative force: tractor laser
Sun, Qiongge; Gao, Long; Li, Chen
2016-01-01
This paper presents a new way of space debris removal and protection, that is, using tractor laser, which based on light negative force, to achieve space debris cleaning and shielded. Tractor laser is traceable from the theory of optical tweezers, accompanied with non-diffraction beam. These kind of optical beams have the force named negative force pointing to optical source, this will bring the object along the trajectory of laser beam moving to the optical source. The negative force leads to the new method to convey and sampling the space micro-objects. In this paper, the application of tractor laser in the space debris collection and protection of 1cm is studied. The application of the several tractor beams in the space debris and sample collection is discussed. The proposed method can reduce the requirements of the laser to the satellite platform, and realize the collection of space debris, make the establishment of the space garbage station possible, and help to study the spatial non contact sample transmission and reduce the risk of space missions.
Bias in Dynamic Monte Carlo Alpha Calculations
Energy Technology Data Exchange (ETDEWEB)
Sweezy, Jeremy Ed [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nolen, Steven Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Terry R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trahan, Travis John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-02-06
A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.
First principle simulations of a bias-dependent electrochemical cell
Pedroza, Luana; Brandimarte, Pedro; Fernandez-Serra, Marivi; Rocha, Alexandre R.
Understanding the local structure of water molecules at the interfaces of metallic electrodes is a key problem in many electrochemical problems. Notably the system is under an external potential bias, which makes the task of simulating this setup difficult. To correctly compute the effect of an external bias potential applied to electrodes, we combine density functional theory and non-equilibrium Green's functions methods, with and without van der Waals interactions. In this work, we apply this methodology to study the electronic properties and forces of water molecules at the interface of different metallic electrodes. We find that the water molecule is sensitive to the sign and magnitude of the applied bias. We also show that it changes the position and orientation of the most stable configuration indicating that the external bias plays an important role in the structural properties of the interface. The authors thank FAPESP and CNPq for financial support.
Daniell method for power spectral density estimation in atomic force microscopy.
Labuda, Aleksander
2016-03-01
An alternative method for power spectral density (PSD) estimation--the Daniell method--is revisited and compared to the most prevalent method used in the field of atomic force microscopy for quantifying cantilever thermal motion--the Bartlett method. Both methods are shown to underestimate the Q factor of a simple harmonic oscillator (SHO) by a predictable, and therefore correctable, amount in the absence of spurious deterministic noise sources. However, the Bartlett method is much more prone to spectral leakage which can obscure the thermal spectrum in the presence of deterministic noise. By the significant reduction in spectral leakage, the Daniell method leads to a more accurate representation of the true PSD and enables clear identification and rejection of deterministic noise peaks. This benefit is especially valuable for the development of automated PSD fitting algorithms for robust and accurate estimation of SHO parameters from a thermal spectrum. PMID:27036781
Osuch, Marzena; Lawrence, Deborah; Meresa, Hadush K.; Napiórkowski, Jaroslaw J.; Romanowicz, Renata J.
2016-04-01
The aim of the study is an estimation of the uncertainty in flood indices introduced by bias correction of climate model variables in ten catchments in Poland. A simulation approach is used to obtain daily flows in catchments under changing climatic conditions, following the RCP4.5 and RCP8.5 emission scenarios. Climate projections were obtained from the EURO-CORDEX initiative, and time series of precipitation and air temperature from different RCM/GCMs for the periods: 1971-2000, 2021-2050 and 2071-2100 were used. The climate model outputs in the Poland area are highly biased; therefore, additional post processing in the form of bias correction of precipitation and temperature is needed. In this work we used four versions of the quantile mapping method (empirical quantile mapping, and three distribution based mappings: double gamma, single gamma and Birnbaum-Sanders) for correction of the precipitation time series and one method for air temperature correction (empirical quantile method). The HBV rainfall-runoff catchment-based model is used to estimate future flow time series. The models are calibrated using the available precipitation, air temperature, and flow observations for the period 1971-2000. Model performance is evaluated using observed data for the period 2001-2010. We also verify performance using the EURO-CORDEX simulations for the reference period (1971-2000), both with and without bias correction of the RCM/GCM outputs. Finally, the models are run for the future climate simulated by the RCM/GCM models for the years: 2021-2050 and 2071-2100. Changes in the mean annual flood and in flood quantiles are analysed and the effect of bias correction on the estimated changes is also considered. The results indicate substantial differences between climate models and catchments. The regional variability has a close relationship with the flood regime type. Catchments where high flows are expected to increase have a rainfall-dominated flood regime in the current
The fast multipole method and point dipole moment polarizable force fields
Coles, Jonathan P.; Masella, Michel
2015-01-01
We present an implementation of the fast multipole method for computing Coulombic electrostatic and polarization forces from polarizable force-fields based on induced point dipole moments. We demonstrate the expected O(N) scaling of that approach by performing single energy point calculations on hexamer protein subunits of the mature HIV-1 capsid. We also show the long time energy conservation in molecular dynamics at the nanosecond scale by performing simulations of a protein complex embedded in a coarse-grained solvent using a standard integrator and a multiple time step integrator. Our tests show the applicability of fast multipole method combined with state-of-the-art chemical models in molecular dynamical systems.
Mirsaidov, Utkur; Polyakov, Yuriy S; Misurkin, Pavel I; Musaev, Ibrahim; Polyakov, Sergey V
2010-01-01
The functional properties of many technological surfaces in biotechnology, electronics, and mechanical engineering depend to a large degree on the individual features of their nanoscale surface texture, which in turn are a function of the surface manufacturing process. Among these features, the surface irregularities and self-similarity structures at different spatial scales, especially in the range of 1 to 100 nm, are of high importance because they greatly affect the surface interaction forces acting at a nanoscale distance. An analytical method for parameterizing the surface irregularities and their correlations in nanosurfaces imaged by atomic force microscopy (AFM) is proposed. In this method, flicker noise spectroscopy - a statistical physics approach - is used to develop six nanometrological parameters characterizing the high-frequency contributions of jump- and spike-like irregularities into the surface texture. These contributions reflect the stochastic processes of anomalous diffusion and inertial e...
Another method to compute the thermodynamic Casimir force in lattice models.
Hasenbusch, Martin
2009-12-01
We discuss a method that allows us to compute the thermodynamic Casimir force at a given temperature in lattice models by performing a single Monte Carlo simulation. It is analogous to the one used by de Forcrand and co-workers in the study of 't Hooft loops and the interface tension in SU(N) lattice gauge models in four dimensions. We test the method at the example of thin films in the XY universality class. In particular we simulate the improved two-component phi4 model on the simple cubic lattice. This allows us to compare with our previous study, where we have computed the Casimir force by numerically integrating energy densities over the inverse temperature. PMID:20365131
Directory of Open Access Journals (Sweden)
Allahyar Geramy
2015-10-01
Full Text Available Objectives: This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths.Materials and Methods: Four 3D finite element method (FEM models of a cer- vical headgear attached to the maxillary first molars were designed in SolidWorks2010 software and transferred to ANSYS Workbench ver. 11 software. Modelscontained the first molars, their periodontal ligament (PDL, cancellous and cor- tical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with dif- ferences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was cal- culated trigonometrically using data from a volunteer.Results: The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N and distal (= 1.008 N forces and also generated moments (5.044 N.mm.Conclusion: As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment. Clinical Relevance:A difference range of 1mm to 15 mm of length in cervical headgear can be consi-dered as a safe length of outer bow shortening in clinical use.
Piche, Steffanie
Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris
Application of Base Force Element Method to Mesomechanics Analysis for Recycled Aggregate Concrete
Yijiang Peng; Yinghua Liu; Jiwei Pu; Lijuan Zhang
2013-01-01
The base force element method (BFEM) on potential energy principle is used to analyze recycled aggregate concrete (RAC) on mesolevel. The model of BFEM with triangular element is derived. The recycled aggregate concrete is taken as five-phase composites consisting of natural coarse aggregate, new mortar, new interfacial transition zone (ITZ), old mortar, and old ITZ on meso-level. The random aggregate model is used to simulate the mesostructure of recycled aggregate concrete. The mechanics pr...
Casimir Forces via Worldline Numerics: Method Improvements and Potential Engineering Applications
Aehlig, Klaus; Fischbacher, Thomas; Gerhard, Jochen
2011-01-01
The string theory inspired Worldline Numerics approach to Casimir force calculations has some favourable characteristics that might make it well suited for geometric optimization problems as they arise e.g. in NEMS device engineering. We explain this aspect in detail, developing some refinements of the method along the way. Also, we comment on the problem of generalizing Worldline Numerics from scalars to photons in the presence of conductors.
SocialFORCE – Methode zur Analyse und Bewertung von viralen Digital-Produkten und -Dienstleistungen
Dirr, Markus
2013-01-01
Die SocialFORCE-Methode liefert ein strukturiertes und methodisches Vorgehen zur Analyse und Bewertung von viralen Digital-Produkten und –Dienstleistung. Es werden verschiedene Arbeitsdiagramme eingeführt und exemplarisch auf SocialMedia-Plattformen bezogen. Eine differenzierte Definition von SocialMedia sowie eine Erläuterung verschiedener Formen der SocialMedia-Landschaft werden theoretisch dargestellt und anhand von praktischen Anwendungsfällen verdeutlicht. Zusammenhänge hinsichtlich d...
Application of Base Force Element Method to Mesomechanics Analysis for Concrete
2014-01-01
The base force element method (BFEM) on damage mechanics is used to analyze the compressive strength, the size effects of compressive strength, and fracture process of concrete at mesolevel. The concrete is taken as three-phase composites consisting of coarse aggregate, hardened cement mortar, and interfacial transition zone (ITZ) on mesolevel. The random aggregate model is used to simulate the mesostructure of concrete. The mechanical properties and fracture process of concrete under uniaxia...
Variable light biasing method to measure component I-V characteristics of multi-junction solar cells
Czech Academy of Sciences Publication Activity Database
Holovský, Jakub; Bonnet-Eymard, M.; Boccard, M.; Despeisse, M.; Ballif, C.
2012-01-01
Roč. 103, č. 8 (2012), s. 128-133. ISSN 0927-0248 R&D Projects: GA ČR GA202/09/0417 Institutional research plan: CEZ:AV0Z10100521 Keywords : current-voltage characteristics * multi-junction * p-i-n * light bias Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.630, year: 2012 http://www.sciencedirect.com/science/article/pii/S0927024812001705
Amano, Ken-ichi
2012-01-01
Recent surface force apparatus (SFA) and atomic force microscopy (AFM) can measure force curves between a probe and a sample surface in solvent. The force curve is thought as the solvation structure in some articles, because its shape is generally oscilltive and pitch of the oscillation is about the same as diameter of the solvent. However, it is not the solvation structure. It is just only a mean force between the probe and the sample surface. Therefore, a relation between the mean force and the solvation structure must be elucidated theoretically to deepen understanding of the measured result (the mean force). In this letter, we briefly explain the relation and a method for comparing the measured mean force and the solvation structure (obtained by a simulation or a liquid theory) by using basic statistical mechanics of liquid.
Development of methods of male contraception： impact of the World Health Organization Task Force
Institute of Scientific and Technical Information of China (English)
GeoffreyM.H.WaitesSc.D
2003-01-01
Objective:To give an historical record of the research of the World Health Organization (WHO) Task Force to develop methods of male contraception; to examine the social, political, medical, pharmaceutical, funding, and other factors that influenced progress; and to suggest reasons why such methods are only now becoming available. Design:Review of basic and clinical research over 30 years. Setting: Task force of a multinational Objective:To give an historical agency and collaborating agencies. Conclusion(s): Through the involvement of many international scientists, the WHO Task Force has uniquely contributed to the exploratory phases of the research in male contraception and by its multicenter contraceptive efficacy studies has accelerated progress towards the ideal hormonal method. Despite an adverse climate involving social and political attitudes, funding constraints, and pharmaceutical industry hesitations, WHO formed coalitions with governments and international agencies to sustain research with results that apply to men in culturally diverse populations and thereby to influence activities across the whole range of global reproductive health and family planning.
Mochizuki, Masahito; Oguchi, Masahiro; Kim, Seong-Oh; Jackman, Joshua A; Ogawa, Tetsu; Lkhamsuren, Ganchimeg; Cho, Nam-Joon; Hayashi, Tomohiro
2015-07-28
Peptide coatings on material surfaces have demonstrated wide application across materials science and biotechnology, facilitating the development of nanobio interfaces through surface modification. A guiding motivation in the field is to engineer peptides with a high and selective binding affinity to target materials. Herein, we introduce a quantitative force mapping method in order to evaluate the binding affinity of peptides to various hydrophilic oxide materials by atomic force microscopy (AFM). Statistical analysis of adhesion forces and probabilities obtained on substrates with a materials contrast enabled us to simultaneously compare the peptide binding affinity to different materials. On the basis of the experimental results and corresponding theoretical analysis, we discuss the role of various interfacial forces in modulating the strength of peptide attachment to hydrophilic oxide solid supports as well as to gold. The results emphasize the precision and robustness of our approach to evaluating the adhesion strength of peptides to solid supports, thereby offering guidelines to improve the design and fabrication of peptide-coated materials. PMID:26125092
International Nuclear Information System (INIS)
We suggest uncertainty compensation methods for the quantification of nanoscale indentation using atomic force microscopy (AFM). The main error factors in the force–distance curves originated from the difference between theoretical and real shape of AFM tip during nanoscale indentation measurements. For the uncertainty compensations of tip shapes and misalignment of loading axis, we applied the enhanced tip geometry function and Y-scanner moving to the AFM measurements. Three different materials such as Si wafer, glass, and Au film were characterized with these compensation methods. By applying compensation methods, our results show the decreased values from 167% to 39% below 100 nm indenting depth compared with the literature values. These compensation methods applied to thin films will show the advanced quantitative analysis of hardness measurements using nanoscale indenting AFM. - Highlights: • We suggest uncertainty compensation methods for quantitative hardness measurement. • The main errors during indentation are tip geometry and non-uniform loading. • 3D tip characterization is obtained by using atomic force microscope scan. • The compensation methods perform well in thin films below thickness of 100 nm
Sandage, Allan; Saha, A.
2002-01-01
Please note that this abstract has been shortened from that found in the paper. A brief history is given of the development of the correction for observation selection bias inherent in the calibration of absolute magnitudes using trigonometric parallaxes. As a tutorial to gain an intuitive understanding of several complicated trigonometric bias problems, we study a toy bias model of a parallax catalog which incorporates assumed parallax measuring errors of various severities. The two effects ...
A Comparison of Force-Time History Analysis Methods for Simplified Aircraft Impact Simulation
International Nuclear Information System (INIS)
In this paper, by comparing the various F-T History analysis method, we are about to propose the most reliable simplified method under the same condition with M-T Interaction analysis method. To find the suitable loading area applied aircraft crash, the studies for a various loading area (Case 1, 2, 3) ware performed using F-T History analysis method, and the former results were compared to the result of Case 4 using M-T Interaction analysis method. The various results according to the proposed loading area were pointed out. Thus, the results for a simplified loading area applied impact load may be fairly sensitive to the assumption associated with loading area. Finally, we can conclude that the Case 3 shows conservative and the most similar results with realistic simulation using M-T Interaction analysis method, i. e., Case 4. The reaction force-time relationship for accidental strike of Boeing 707-320 aircraft against a rigid surface was proposed by Riera. After that, the aircraft impact analysis has been studied significantly in the last few decades. The only way to acquire an exact solution of the aircraft impact analysis is direct impact test. However, for the large commercial aircraft impact, this direct test has been hardly performed because the scale of aircraft and impacted wall is very huge. Up to date, the numerical simulation using Missile-Target (M-T) Interaction analysis method is known as the only way to obtain a relatively accurate solution. However, because of its massive computational efforts and modeling complexity, this method is inadequate and inefficient to the application of the fragility analysis and risk assessments which is required many times of iterative simulations. Thus, a more simplified and conservative analysis method is required. The simplified method such as Force-Time (F-T) History analysis method has been studied by Riera, Sugano et al., Mullapudi et al. and etc.
MohammadReza Zare; Mousa Marzband
2010-01-01
In permanent magnet (PM) linear motor, there is force ripple, which is detrimental to positioning. This force ripple is mainly due to cogging force and mutual force ripple. These forces are affected by geometric parameters of brushless PM motor, such as width of magnet, height of magnet, shifted length of magnet pole, length and height of armature and slot width. If flux density distribution can be described by geometric parameters that are related to the force ripple and force ripple is desc...
Boundary Element Method Solution in the Time Domain For a Moving Time-Dependent Force
DEFF Research Database (Denmark)
Nielsen, Søren R.K.; Kirkegaard, Poul Henning; Rasmussen, K. M.
2001-01-01
The problem of a moving time dependent concentrated force on the surface of an elastic halfspace is of interest in the analysis of traffic generated noise. The Boundary element method (BEM) is superior to the finite element method (FEM) in solving such problems due to its inherent ability so...... satisfy the radiation conditions exactly. In this paper a model based on the BEM is formulated for the solution of the mentioned problem. A numerical solution is obtained for the 2D plane strain case, and comparison is made with the results obtained from a corresponding FEM solution with an impedance...
The Fast Multipole Method and Point Dipole Moment Polarizable Force Fields
Coles, Jonathan P
2014-01-01
We present a momentum conserving implementation of the fast multipole method for computing coulombic electrostatic and polarization forces from polarizable force-fields based on induced point dipole moments. We demonstrate the expected $O(N)$ scaling of that approach by performing single energy point calculations on hexamer protein subunits of the mature HIV-1 capsid. We also show the long time energy conservation in molecular dynamics at the nanosecond scale by performing simulations of a protein complex embedded in a coarse-grained solvent using both a standard integrator and a multiple time step one. Our tests show the applicability of FMM combined with state-of-the-art chemical models in molecular dynamical systems.
A combined lorentz-force and optical detection method for inclusion detection in molten metal
International Nuclear Information System (INIS)
The detection and removal of small-scale inclusions in molten metal has been a key issue for the aluminum casting industry. Silicon carbide and oxides particles of diameters as small as 10 to 20 micrometers are sizes that are encountered in the melt that should be reliably detected. We have developed an electromagnetic method utilizing heavy direct and alternating currents in conjunction with either the self-induced or an external magnetic field to generate a Lorentz force density in the melt. In response to the downward pressure on the melt, nonconducting inclusions are forced to the free melt surface. Appropriate mechanical and acoustic surface conditioning is used to enable particle escape. Finally, a optical detection system based on a CCD camera allows the quantitative classification of the inclusions
Application of stochastic variational method to 3-4 body systems with realistic nuclear force
Energy Technology Data Exchange (ETDEWEB)
Ohbayashi, Yoshihide [Niigata Univ. (Japan); Varga, K.; Suzuki, Yoshiyuki
1997-05-01
SVM (stochastic variational method) was applied to simulate triton and alpha with realistic nuclear force such as Reid V8 (RV8), Argonne V6, V8 (AV6 and aV8). 3-4 body systems were solved by about 300-400 dimensions and the results were agreed with the most accurate solution. Convergence of energy of 3-4 body systems was rapid by using AV6 and AV8 potential, but it was slow by RV8 with strong repulsive force core. The energy values using SVM and GFMC were almost same. Number of dimension to convert the energy of triton was decreased by refinement. (S.Y.)
Alternative method to control radiative vortex forces in a magneto-optical trap
International Nuclear Information System (INIS)
We present an experimental and theoretical study of controlling the atomic spatial distributions in a magneto-optical trap (MOT). With a diaphragm we can vary the waist and power of one of the cooling laser beams and we can change parameters of large-diameter, parallelogram-shaped atomic orbits. We show that the radiative force generated by the repumping MOT laser has to be taken into consideration. Computer simulations of atomic trajectories explain the observed spatial structures, and we employ these simulations to present potential applications of controlling the diaphragm diameter as a function of time. A potential use of controlled vortex forces seems to have a great significance in recently presented important new methods to investigate cold atom collisions in the MOT, which were recently published
Accurate computation of surface stresses and forces with immersed boundary methods
Goza, Andres; Morley, Benjamin; Colonius, Tim
2016-01-01
Many immersed boundary methods solve for surface stresses that impose the velocity boundary conditions on an immersed body. These surface stresses may contain spurious oscillations that make them ill-suited for representing the physical surface stresses on the body. Moreover, these inaccurate stresses often lead to unphysical oscillations in the history of integrated surface forces such as the coefficient of lift. While the errors in the surface stresses and forces do not necessarily affect the convergence of the velocity field, it is desirable, especially in fluid-structure interaction problems, to obtain smooth and convergent stress distributions on the surface. To this end, we show that the equation for the surface stresses is an integral equation of the first kind whose ill-posedness is the source of spurious oscillations in the stresses. We also demonstrate that for sufficiently smooth delta functions, the oscillations may be filtered out to obtain physically accurate surface stresses. The filtering is a...
Estimation of tensile force in tie-rods using a frequency-based identification method
Amabili, M.; Carra, S.; Collini, L.; Garziera, R.; Panno, A.
2010-05-01
A technique is developed to identify in-situ the tensile force in tie-rods which are used in ancient monumental masonry buildings to eliminate the lateral load exercised by the vaults and arcs. The technique is based on a frequency-based identification method that allows to minimize the measurement error and that is of simple execution. In particular, the first natural frequencies of the tie-rods are experimentally identified by measuring the frequency response functions (FRFs) with instrumented hammer excitation; four to six natural frequencies can be easily identified with a simple test. Then, a numerical model, based on the Rayleigh-Ritz method, is developed for the axially loaded tie-rod by using the Timoshenko beam theory retaining shear deformation and rotary inertia. Non-uniform section of the rod is considered since this is often the case for hand-made tie-rods in old buildings. The part of the tie-rod inserted inside the masonry wall is also modeled and a simple support is assumed at the extremities inside the walls. The constraints given to the part of the tie-rod inserted inside the masonry structure are assumed to be elastic foundations. The tensile force and the stiffness of the foundation are the unknowns. In some cases, the length of the rod inside the masonry wall can be also assumed as unknown. The numerical model is used to calculate the natural frequencies for a given set of unknowns. Then, a weighted difference between the calculated and identified natural frequencies is calculated and this difference is minimized in order to identify the unknowns, and in particular the tensile force. An estimation of the error in the identification of the force is given. The technique has been tested on five tie-rods at the ground floor of the famous castle of Fontanellato, Italy.
A simple method to construct soliton-like solution of the general KdV equation with external force
Institute of Scientific and Technical Information of China (English)
JiefangZHANG; FengminWU
2000-01-01
A simple and direct method is described to construct the soliton-like solution for the general KdV equation with external force. Crucial to the method is the assumption that the solution chosen is a special truncated expansion.
A direct micropipette-based calibration method for atomic force microscope cantilevers
Energy Technology Data Exchange (ETDEWEB)
Liu Baoyu; Yu Yan; Yao Dakang; Shao Jinyu [Department of Biomedical Engineering, Washington University, Saint Louis, Missouri 63130 (United States)
2009-06-15
In this report, we describe a direct method for calibrating atomic force microscope (AFM) cantilevers with the micropipette aspiration technique (MAT). A closely fitting polystyrene bead inside a micropipette is driven by precisely controlled hydrostatic pressures to apply known loads on the sharp tip of AFM cantilevers, thus providing a calibration at the most functionally relevant position. The new method is capable of calibrating cantilevers with spring constants ranging from 0.01 to hundreds of newtons per meter. Under appropriate loading conditions, this new method yields measurement accuracy and precision both within 10%, with higher performance for softer cantilevers. Furthermore, this method may greatly enhance the accuracy and precision of calibration for colloidal probes.
Three-body forces for electrons by the S-matrix method
International Nuclear Information System (INIS)
A electromagnetic three-body potential between eletrons is derived by the S-matrix method. This potential can be compared up to a certain point with other electromagnetic potentials (obtained by other methods) encountered in the literature. However, since the potential derived here is far more complete than others, this turns direct comparison with the potentials found in the literature somewhat difficult. These calculations allow a better understanding of the S-matrix method as applied to problems which involve the calculations of three-body nuclear forces (these calculations are performed in order to understand the 3He form factor). Furthermore, these results enable us to decide between two discrepant works which derive the two-pion exchange three-body potential, both by the S-matrix method. (author)
Energy Technology Data Exchange (ETDEWEB)
Hur, J.; Chun, Y.D.; Lee, J.; Hyun, D.S. [Hanyang Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering
1998-09-01
The distribution of radial force density in brushless permanent magnet DC motor is not uniform in axial direction. The analysis of radial force density has to consider the 3-D shape of teeth and overhand, because the radial force density causes vibration and acts on the surface of teeth inconstantly. For the analysis, a new 3-D equivalent magnetic circuit network method is used to account the rotor movement without remesh. The radial force density is calculated and analyzed by Maxwell stress tensor and discrete Fourier transform (DFT) respectively. The results of 3-D equivalent magnetic circuit method have been compared with the results of 3-D FEM.
Measuring nonlocal Lagrangian peak bias
Biagetti, Matteo; Desjacques, Vincent; Paranjape, Aseem
2013-01-01
In the Lagrangian approach to halo clustering, nonlocal bias can be generated either in the initial conditions or by the subsequent gravitational motions. Here, we investigate nonlocal Lagrangian bias contributions involving gradients of the linear density field, for which we have predictions from the excursion set peak formalism. We reformulate this approach in order to explicitly take into account the variable describing the crossing of the collapse barrier. This enables us to write down a bias expansion which includes all the bias terms, including the nonlocal ones. Having checked that the model furnishes a reasonable fit to the halo mass function, we extend the 1-point cross-correlation technique of Musso, Paranjape & Sheth (2012) to bias contributions that are chi-squared distributed. We validate the method with numerical realizations of peaks of Gaussian random fields before applying it to N-body simulations. We focus on the lowest (quadratic) order nonlocal bias factors predicted by the excursion s...
Resonant multi-frequency method for Kelvin probe force microscopy in air
International Nuclear Information System (INIS)
The multi-frequency method, recently introduced in atomic force microscopy (AFM), has shown remarkable enhancement of sensitivity and resolution of microscopy with a variety of heterogeneous materials. Under ambient conditions, Kelvin probe force microscopy (KPFM) is commonly carried out using only the first flexural eigenmode of the micro-cantilever probe. Here we report a resonant multi-frequency method for KPFM in air. To implement this method, the first eigenmode of the cantilever probe is used for topography imaging, whereas the second one is used to measure the local contact potential difference in the two-pass mode with the tip lifted. By introducing an additional feedback controller, a multi-frequency KPFM (MF-KPFM) is developed upon a commercial AFM. The performance of MF-KPFM, including the feedback controller, sensitivity and noise, lift height of the cantilever and lateral resolution, is evaluated and optimized. The capabilities of MF-KPFM are demonstrated by characterizing a charge pattern on a polymer electret. The results show that the lateral resolution of KPFM in air can be improved by the resonant multi-frequency method. (paper)
International Nuclear Information System (INIS)
For SU(2) hamiltonian lattice gauge theory we calculate the ground-state energy per plaquette and the glueball mass in 2 + 1 and 3 + 1 dimensions. In 2 + 1 dimensions, the calculations are made both analytically and using the Biased-Selection Monte Carlo (BSMC) method. In 3 + 1 dimensions the BSMC method alone was used to estimate the plaquette expectation value from which the other quantities can be calculated in our approximation. These calculations required about 10 minutes of IBM 3090-400 CPU time. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Huang, M.C.; Coldwell, R.L.; Katoot, M.W.
1988-11-21
For SU(2) hamiltonian lattice gauge theory we calculate the ground-state energy per plaquette and the glueball mass in 2 + 1 and 3 + 1 dimensions. In 2 + 1 dimensions, the calculations are made both analytically and using the Biased-Selection Monte Carlo (BSMC) method. In 3 + 1 dimensions the BSMC method alone was used to estimate the plaquette expectation value from which the other quantities can be calculated in our approximation. These calculations required about 10 minutes of IBM 3090-400 CPU time.
Compensation Method for Die Shift Caused by Flow Drag Force in Wafer-Level Molding Process
Directory of Open Access Journals (Sweden)
Simo Yeon
2016-05-01
Full Text Available Wafer-level packaging (WLP is a next-generation semiconductor packaging technology that is important for realizing high-performance and ultra-thin semiconductor devices. However, the molding process, which is a part of the WLP process, has various problems such as a high defect rate and low predictability. Among the various defect factors, the die shift primarily determines the quality of the final product; therefore, predicting the die shift is necessary to achieve high-yield production in WLP. In this study, the die shift caused by the flow drag force of the epoxy molding compound (EMC is evaluated from the die shift of a debonded molding wafer. Experimental and analytical methods were employed to evaluate the die shift occurring during each stage of the molding process and that resulting from the geometrical changes after the debonding process. The die shift caused by the EMC flow drag force is evaluated from the data on die movements due to thermal contraction/expansion and warpage. The relationship between the die shift and variation in the die gap is determined through regression analysis in order to predict the die shift due to the flow drag force. The results can be used for die realignment by predicting and compensating for the die shift.
Bharathy, P. Vijai; Nataraj, D.; Chu, Paul K.; Wang, Huaiyu; Yang, Q.; Kiran, M. S. R. N.; Silvestre-Albero, J.; Mangalaraj, D.
2010-10-01
Amorphous diamond like carbon (DLC) and titanium incorporated diamond like carbon (Ti-DLC) thin films were deposited by using reactive-biased target ion beam deposition method. The effects of Ti incorporation and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and nano-indentation. It was found that the Ti content in Ti-DLC films gets increased with increasing target bias voltage. At about 4.2 at.% of Ti, uniform sized well dispersed nanocrystals were seen in the DLC matrix. Using FFT analysis, a facility available in the TEM, it was found that the nanocrystals are in cubic TiC phase. Though at the core, the incorporated Ti atoms react with carbon to form cubic TiC; most of the surface exposed Ti atoms were found to react with the atmospheric oxygen to form weakly bonded Ti-O. The presence of TiC nanocrystals greatly modified the sp 3/sp 2 hybridized bonding ratio and is reflected in mechanical hardness of Ti-DLC films. These films were then tested for their biocompatibility by an invitro cell culturing test. Morphological observation and the cell proliferation test have demonstrated that the human osteoblast cells well attach and proliferate on the surface of Ti incorporated DLC films, suggesting possible applications in bone related implant coatings.
International Nuclear Information System (INIS)
Amorphous diamond like carbon (DLC) and titanium incorporated diamond like carbon (Ti-DLC) thin films were deposited by using reactive-biased target ion beam deposition method. The effects of Ti incorporation and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and nano-indentation. It was found that the Ti content in Ti-DLC films gets increased with increasing target bias voltage. At about 4.2 at.% of Ti, uniform sized well dispersed nanocrystals were seen in the DLC matrix. Using FFT analysis, a facility available in the TEM, it was found that the nanocrystals are in cubic TiC phase. Though at the core, the incorporated Ti atoms react with carbon to form cubic TiC; most of the surface exposed Ti atoms were found to react with the atmospheric oxygen to form weakly bonded Ti-O. The presence of TiC nanocrystals greatly modified the sp3/sp2 hybridized bonding ratio and is reflected in mechanical hardness of Ti-DLC films. These films were then tested for their biocompatibility by an invitro cell culturing test. Morphological observation and the cell proliferation test have demonstrated that the human osteoblast cells well attach and proliferate on the surface of Ti incorporated DLC films, suggesting possible applications in bone related implant coatings.
Cognitive biases and language universals
Baronchelli, Andrea; Puglisi, Andrea
2013-01-01
Language universals have been longly attributed to an innate Universal Grammar. An alternative explanation states that linguistic universals emerged independently in every language in response to shared cognitive, though non language-specific, biases. A computational model has recently shown how this could be the case, focusing on the paradigmatic example of the universal properties of color naming patterns, and producing results in accurate agreement with the experimental data. Here we investigate thoroughly the role of a cognitive bias in the framework of this model. We study how, and to what extent, the structure of the bias can influence the corresponding linguistic universal patterns. We show also that the cultural history of a group of speakers introduces population-specific constraints that act against the uniforming pressure of the cognitive bias, and we clarify the interplay between these two forces. We believe that our simulations can help to shed light on the possible mechanisms at work in the evol...
Jiang Hualiang; Li Jiabo; Zhang Haoyun; Liu Xiaofeng; Bai Fang; Wang Xicheng; Li Honglin
2010-01-01
Abstract Background Conformational sampling for small molecules plays an essential role in drug discovery research pipeline. Based on multi-objective evolution algorithm (MOEA), we have developed a conformational generation method called Cyndi in the previous study. In this work, in addition to Tripos force field in the previous version, Cyndi was updated by incorporation of MMFF94 force field to assess the conformational energy more rationally. With two force fields against a larger dataset ...
IMPROVED FABRICATION METHOD FOR CARBON NANOTUBE PROBE OF ATOMIC FORCE MICROSCOPY(AFM)
Institute of Scientific and Technical Information of China (English)
XU Zongwei; DONG Shen; GUO Liqiu; ZHAO Qingliang
2006-01-01
An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy (AFM) here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two high precision microtranslators. When silicon probe and carbon nanotube are very close, several tens voltage is applied between them. And carbon nanotube is divided and attached to the end of silicon probe, which mainly due to the arc welding function.Comparing with the arc discharge method before, the new method here needs no coat silicon probe with metal film in advance, which can greatly reduce the fabrication's difficulty. The fabricated carbon nanotube probe shows good property of higher aspect ratio and can more accurately reflect the true topography of silicon grating than silicon probe. Under the same image drive force, carbon nanotube probe had less indentation depth on soft triblock copolymer sample than silicon probe. This showed that carbon nanotube probe has lower spring constant and less damage to the scan sample than silicon probe.
International Nuclear Information System (INIS)
A general method based on the combination of electrostatic force microscopy with thermal cycling of the substrate holder is presented for direct, nanoscale characterization of the pyroelectric effect in a range of materials and sample configurations using commercial atomic force microscope systems. To provide an example of its broad applicability, the technique was applied to the examination of natural tourmaline gemstones. The method was validated using thermal cycles similar to those experienced in ambient conditions, where the induced pyroelectric response produced localized electrostatic surface charges whose magnitude demonstrated a correlation with the iron content and heat dissipation of each gemstone variety. In addition, the surface charge was shown to persist even at thermal equilibrium. This behavior is attributed to constant, stochastic cooling of the gemstone surface through turbulent contact with the surrounding air and indicates a potential utility for energy harvesting in applications including environmental sensors and personal electronics. In contrast to previously reported methods, ours has a capacity to carry out such precise nanoscale measurements with little or no restriction on the sample of interest, and represents a powerful new tool for the characterization of pyroelectric materials and devices. (paper)
A body-force based method to generate supersonic equilibrium turbulent boundary layer profiles
Waindim, M.; Gaitonde, D. V.
2016-01-01
We further develop a simple counterflow body force-based approach to generate an equilibrium spatially developing turbulent boundary layer suitable for Direct Numerical Simulations (DNS) or Large Eddy Simulations (LES) of viscous-inviscid interactions. The force essentially induces a small separated region in an incoming specified laminar boundary layer. The resulting unstable shear layer then transitions and breaks down to yield the desired unsteady profile. The effects of wall thermal conditions are explored to demonstrate the capability of the method for both fixed wall and adiabatic wall conditions. We then describe an efficient method to select parameters that ensure transition by examining precursor signatures using generalized stability variables. These precursors are shown to be evident in a computational domain spanning only a small region around the trip and can also be detected using 2D simulations. Finally, the method is tested for different Mach numbers ranging from 1.7 to 2.9, with emphasis on flow field surveys, Reynolds stresses, and energy spectra. These results provide guidance on boundary conditions for desired boundary layer thickness at each Mach number. The consequences of using a much lower Reynolds number in computation relative to experiment are evident at the higher Mach number, where a self sustaining turbulent boundary layer is more difficult to obtain.
Martin-Olmos, Cristina; Stieg, Adam Z.; Gimzewski, James K.
2012-06-01
A general method based on the combination of electrostatic force microscopy with thermal cycling of the substrate holder is presented for direct, nanoscale characterization of the pyroelectric effect in a range of materials and sample configurations using commercial atomic force microscope systems. To provide an example of its broad applicability, the technique was applied to the examination of natural tourmaline gemstones. The method was validated using thermal cycles similar to those experienced in ambient conditions, where the induced pyroelectric response produced localized electrostatic surface charges whose magnitude demonstrated a correlation with the iron content and heat dissipation of each gemstone variety. In addition, the surface charge was shown to persist even at thermal equilibrium. This behavior is attributed to constant, stochastic cooling of the gemstone surface through turbulent contact with the surrounding air and indicates a potential utility for energy harvesting in applications including environmental sensors and personal electronics. In contrast to previously reported methods, ours has a capacity to carry out such precise nanoscale measurements with little or no restriction on the sample of interest, and represents a powerful new tool for the characterization of pyroelectric materials and devices.
A Spanish continuous voluntary web survey: sample bias, weighting and efficiency
Pedraza,, I.; Tijdens, K.; Muñoz de Bustillo, R.; Steinmetz, S
2010-01-01
Using micro data from a continuous volunteer web survey (CVWS), the WageIndicator (WI), this paper firstly analyses the type of bias that such a survey method produces. Secondly, following a «modelbased » approach, two alternative data weighting methodologies are implemented. Thirdly, in order to test whether weighting corrects the bias, thus making it possible to obtain conclusions applicable to the whole labour force, the efficiency of the weighting methodologies is evaluated. Since the Wag...
Energy Technology Data Exchange (ETDEWEB)
Xiong, Jie L. [Faculty of Engineering, University of Hong Kong (Hong Kong); Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL, 61801 (United States); Tong, M.S. [Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL, 61801 (United States); Atkins, Phillip [Faculty of Engineering, University of Hong Kong (Hong Kong); Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL, 61801 (United States); Chew, W.C., E-mail: wcchew@hku.h [Faculty of Engineering, University of Hong Kong (Hong Kong); Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL, 61801 (United States)
2010-05-31
In this Letter, we generalized the surface integral equation method for the evaluation of Casimir force in arbitrary three-dimensional geometries. Similar to the two-dimensional case, the evaluation of the mean Maxwell stress tensor is cast into solving a series of three-dimensional scattering problems. The formulation and solution of the three-dimensional scattering problems are well-studied in classical computational electromagnetics. This Letter demonstrates that this quantum electrodynamic phenomenon can be studied using the knowledge and techniques of classical electrodynamics.
Characterization of single-crystal sapphire substrates by X-ray methods and atomic force microscopy
International Nuclear Information System (INIS)
The possibility of characterizing a number of practically important parameters of sapphire substrates by X-ray methods is substantiated. These parameters include wafer bending, traces of an incompletely removed damaged layer that formed as a result of mechanical treatment (scratches and marks), surface roughness, damaged layer thickness, and the specific features of the substrate real structure. The features of the real structure of single-crystal sapphire substrates were investigated by nondestructive methods of double-crystal X-ray diffraction and plane-wave X-ray topography. The surface relief of the substrates was investigated by atomic force microscopy and X-ray scattering. The use of supplementing analytical methods yields the most complete information about the structural inhomogeneities and state of crystal surface, which is extremely important for optimizing the technology of substrate preparation for epitaxy.
Measuring the loss tangent of polymer materials with atomic force microscopy based methods
International Nuclear Information System (INIS)
Atomic force microscopy (AFM) quantitatively maps viscoelastic parameters of polymers on the nanoscale by several methods. The loss tangent, the ratio between dissipated and stored energy, was measured on a blend of thermoplastic polymer materials by a dynamic contact method, contact resonance, and by a recently developed loss tangent measurement by amplitude modulation AFM. Contact resonance measurements were performed both with dual AC resonance tracking and band excitation (BE), allowing for a reference-free measurement of the loss tangent. Amplitude modulation AFM was performed where a recent interpretation of the phase signal under certain operating conditions allows for the loss tangent to be calculated. The loss tangent measurements were compared with values expected from time–temperature superposed frequency-dependent dynamical mechanical curves of materials and reveal that the loss tangents determined from the BE contact resonance method provide the most accurate values. (paper)
DEFF Research Database (Denmark)
Hasmasan, Adrian Augustin; Busca, Christian; Teodorescu, Remus;
2012-01-01
In this paper, a FEM (finite element method) based mechanical model for PP (press-pack) IGBTs (insulated gate bipolar transistors) is presented, which can be used to calculate the clamping force distribution among chips under various clamping conditions. The clamping force is an important parameter...
Bias in Absolute Magnitude Determination from Parallaxes
Feast, Michael
2002-01-01
Relations are given for the correction of bias when mean absolute magnitudes are derived by the method of reduced parallaxes. The bias in the case of the derivation of the absolute magnitudes of individual objects is also considered.
International Nuclear Information System (INIS)
In this work the geometry,force constants and vibrational frequencies are calculated for some hydrocarbones (ethane,propane,isobutane,neopentane,cyclopropane,cyclo-butanol) using the MINDO/3 methode(Modifie Iintermediate Neglect of Differential Overlap).The force constants are calculated using MINDO/3.Force programe when we modified this program by fixed the wave function which is used in the calculation of the force of the molecules with respect of cartisan coordinate.The research includes many steps as following:-1 1-Calculated the coordinates of the equilibruim geometry of the molecules by use (COAT) program. 2-Calculated the force constant by used MINDO/3 force program. 3-Calculate the elements of the atomic mass matrix. 4-Calculates the vibrational frequencies by solvent the secular equation.(6 tabs., 6 figs., 43 refs.)
A rate adaptive control method for Improving the imaging speed of atomic force microscopy
International Nuclear Information System (INIS)
A simple rate adaptive control method is proposed to improve the imaging speed of the atomic force microscope (AFM) in the paper. Conventionally, the probe implemented on the AFM scans the sample surface at a constant rate, resulting in low time efficiency. Numerous attempts have been made to realize high-speed AFMs, while little efforts are put into changing the constant-rate scanning. Here we report a rate adaptive control method based on variable-rate scanning. The method automatically sets the imaging speed for the x scanner through the analysis of the tracking errors in the z direction at each scanning point, thus improving the dynamic tracking performance of the z scanner. The development and functioning of the rate adaptive method are demonstrated, as well as how the approach significantly achieves faster scans and a higher resolution AFM imaging. - Highlights: • A rate adaptive control method is proposed to improve the imaging speed ofAFM. • The new method automatically selects appropriate scanning speed in the x direction through the analysis of the tracking errors in the z direction. • The system identification is carried out to obtain the mathematical model of thevertical feedback system of AFM
Identification Method of Sports Throwing Force Based on Fuzzy Neural Network
Directory of Open Access Journals (Sweden)
Rui Su
2013-07-01
Full Text Available In order to speed up the defects of the neural network computing and recognition, the essay proposes the information identification method research of sports throwing force based on the fuzzy neural network model. Firstly, I use the information, which is the combination of the wavelet transformation and the fuzzy neural network, to identify the new method combining and make the noise-suppressed processing of information. Then, according to the athlete’s throwing action and the extraction of signal processing characteristics, as well as the analysis of the fuzzy neural network algorithm. Finally, in order to verify the effectiveness of the proposed algorithm, I make analysis for the experimental results, which indicates that using this algorithm can not only have less noise than the traditional algorithm, but also have less number of the neural network computation. Besides, its recognition speed and accuracy is also higher.
Yuan, Jianping; Zhu, Zhanxia; Ming, Zhenfeng; Luo, Qiuyue
2015-07-01
This paper proposes an innovative method for simulating space microgravity effects. The new approach combines the neutral buoyancy and the electromagnetic force on the tested-body to balance the gravity and simulate the microgravity effects. In the paper, we present in some detail the magnetism-buoyancy hybrid microgravity simulation system, its components, functions and verification. We describe some key techniques such as ground-space similarity, the homogenization of electromagnetic field, the precise control of microgravity effects in dynamic environment, measurement in the hybrid suspension system. With this innovative microgravity simulation system, we prove through experiments and tests that our innovative method is feasible and effective and that the simulation fidelity is even higher than the neutral buoyancy system.
Wave system fitting: A new method for force measurements in shock tunnels with long test duration
Luo, Changtong; Wang, Yunpeng; Wang, Chun; Jiang, Zonglin
2015-10-01
Force measurements in shock tunnels are difficult due to the existence of vibrations excited by a sudden aerodynamic loading. Accelerometer inertia compensation could reduce its negative effect to some extent, but has inherent problems. A new signal decomposition method, wave system fitting (WSF), is proposed to remove vibration waves of low frequency. The WSF is accelerometer-free. It decomposes the balance signal and can separate vibration waves without the influence on the DC component, and it does work no matter the cycle of the sample signal is complete or not. As a standard signal post-processing tool in JF-12, the application results show that it works reliably with high accuracy, and it can also explain puzzling signals encountered in JF-12. WSF method is especially useful and irreplaceable whenever only a few cycles of a periodic signal could be obtained, as is usual for shock tunnels.
2004-01-01
The grant closure report is organized in the following four chapters: Chapter describes the two research areas Design optimization and Solid mechanics. Ten journal publications are listed in the second chapter. Five highlights is the subject matter of chapter three. CHAPTER 1. The Design Optimization Test Bed CometBoards. CHAPTER 2. Solid Mechanics: Integrated Force Method of Analysis. CHAPTER 3. Five Highlights: Neural Network and Regression Methods Demonstrated in the Design Optimization of a Subsonic Aircraft. Neural Network and Regression Soft Model Extended for PX-300 Aircraft Engine. Engine with Regression and Neural Network Approximators Designed. Cascade Optimization Strategy with Neural network and Regression Approximations Demonstrated on a Preliminary Aircraft Engine Design. Neural Network and Regression Approximations Used in Aircraft Design.
Directory of Open Access Journals (Sweden)
Lee Wah
2008-09-01
Full Text Available Abstract Background Pathogen detection using DNA microarrays has the potential to become a fast and comprehensive diagnostics tool. However, since pathogen detection chips currently utilize random primers rather than specific primers for the RT-PCR step, bias inherent in random PCR amplification becomes a serious problem that causes large inaccuracies in hybridization signals. Results In this paper, we study how the efficiency of random PCR amplification affects hybridization signals. We describe a model that predicts the amplification efficiency of a given random primer on a target viral genome. The prediction allows us to filter false-negative probes of the genome that lie in regions of poor random PCR amplification and improves the accuracy of pathogen detection. Subsequently, we propose LOMA, an algorithm to generate random primers that have good amplification efficiency. Wet-lab validation showed that the generated random primers improve the amplification efficiency significantly. Conclusion The blind use of a random primer with attached universal tag (random-tagged primer in a PCR reaction on a pathogen sample may not lead to a successful amplification. Thus, the design of random-tagged primers is an important consideration when performing PCR.
Juang, Jer-Nan; Wright, Jan R.
1989-01-01
Force appropriation methods aim to provide an estimate for the force pattern required to excite a 'pure' normal mode in a vibration test where multiple exciters are available. In this paper, a new method based upon a Singular Value Decompositon approach is presented. The appropriated force vector which minimizes the in-plane response components while maximizing the required quadrature components is found, subject to a fixed force norm. The method can accommodate more transducers than exciters and also more exciters than effective degrees of freedom. The method is demonstrated upon a six degree of freedom theoretical model and it is shown that an estimate for the effective degrees of freedom can be obtained.
International Nuclear Information System (INIS)
Structural health monitoring (SHM) consists of the continuous or periodic measurement of structural parameters and their analysis with the aim of deducing information about the performance and health condition of a structure. The significant increase in the construction of prestressed concrete bridges motivated this research on an SHM method for the on-site determination of the distribution of prestressing forces along prestressed concrete beam structures. The estimation of the distribution of forces is important as it can give information regarding the overall performance and structural integrity of the bridge. An inadequate transfer of the designed prestressing forces to the concrete cross-section can lead to a reduced capacity of the bridge and consequently malfunction or failure at lower loads than predicted by design. This paper researches a universal method for the determination of the distribution of prestressing forces along concrete beam structures at the time of transfer of the prestressing force (e.g., at the time of prestressing or post-tensioning). The method is based on the use of long-gauge fiber optic sensors, and the sensor network is similar (practically identical) to the one used for damage identification. The method encompasses the determination of prestressing forces at both healthy and cracked cross-sections, and for the latter it can yield information about the condition of the cracks. The method is validated on-site by comparison to design forces through the application to two structures: (1) a deck-stiffened arch and (2) a curved continuous girder. The uncertainty in the determination of prestressing forces was calculated and the comparison with the design forces has shown very good agreement in most of the structures’ cross-sections, but also helped identify some unusual behaviors. The method and its validation are presented in this paper. (papers)
Forced degradation of nepafenac: Development and validation of stability indicating UHPLC method.
Runje, Mislav; Babić, Sandra; Meštrović, Ernest; Nekola, Irena; Dujmić-Vučinić, Željka; Vojčić, Nina
2016-05-10
This paper presents stability study of the nonsteroidal anti-inflammatory drug (NSAID) nepafenac. In order to investigate stability of nepafenac, it was subjected to forced degradation under different stress conditions: acid and base hydrolysis, oxidation, humidity, heat and light. A novel stability indicating reverse phase ultra high performance liquid chromatographic (UHPLC) method coupled to ultraviolet detector has been developed to separate nepafenac and all related compounds (2-aminobenzophenone, Cl-thionepafenac, thionepafenac, Cl-nepafenac, hydroxy-nepafenac, and cyclic-nepafenac). Efficient chromatographic separation was achieved on a Waters Acquity BEH C18 stationary phase with a gradient elution. Quantification was carried out at 235 nm at a flow rate of 0.6 mL/min(-1). The resolution between nepafenac and six potential impurities is found to be greater than 2.0. The developed method was validated with respect to specificity, LOD, LOQ, linearity, precision, accuracy and robustness. The r(2) values for nepafenac and six potential impurities were all greater than 0.999. The developed method is capable to detect impurities of nepafenac at a level of 0.005% with respect to test concentration of 1.0mg/mL. Significant degradation is observed in acid, base and oxidative degradation conditions and degradation products (DPs) were identified using mass spectrometry analysis; two of them were found to be a known process related impurities (hydroxy- and cyclic-nepafenac) whereas four degradation products were identified as new degradation impurities. The forced degradation samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.5%. PMID:26871279
Multi-Sphere Method for modeling spacecraft electrostatic forces and torques
Stevenson, Daan; Schaub, Hanspeter
2013-01-01
The use of electrostatic (Coulomb) actuation for formation flying is attractive because non-renewable fuel reserves are not depleted and plume impingement issues are avoided. Prior analytical electrostatic force models used for Coulomb formations assume spherical spacecraft shapes, which include mutual capacitance and induced effects. However, this framework does not capture any orientation-dependent forces or torques on generic spacecraft geometries encountered during very close operations and docking scenarios. The Multi-Sphere Method (MSM) uses a collection of finite spheres to represent a complex shape and analytically approximate the Coulomb interaction with other charged bodies. Finite element analysis software is used as a truth model to determine the optimal sphere locations and radii. The model is robust to varying system parameters such as prescribed voltages and external shape size. Using the MSM, faster-than-realtime electrostatic simulation of six degree of freedom relative spacecraft motion is feasible, which is crucial for the development of robust relative position and orientation control algorithms in local space situational awareness applications. To demonstrate this ability, the rotation of a cylindrical craft in deep space is simulated, while charge control from a neighboring spacecraft is used to de-spin the object. Using a 1 m diameter craft separated by 10 m from a 3 by 1 m cylindrical craft in deep space, a 2 °/s initial rotation rate can be removed from the cylinder within 3 days, using electric potentials up to 30 kV.
Directory of Open Access Journals (Sweden)
Gil Herrnstadt
2015-03-01
The protocol was designed to engage the user in an assortment of static and dynamic arm matching and opposing tasks. The training incorporates force feedback movements, force feedback positioning, and force matching tasks with same and opposite direction movements. We are able to suggest identification
Identifying a robust method to build RCMs ensemble as climate forcing for hydrological impact models
Olmos Giménez, P.; García Galiano, S. G.; Giraldo-Osorio, J. D.
2016-06-01
The regional climate models (RCMs) improve the understanding of the climate mechanism and are often used as climate forcing to hydrological impact models. Rainfall is the principal input to the water cycle, so special attention should be paid to its accurate estimation. However, climate change projections of rainfall events exhibit great divergence between RCMs. As a consequence, the rainfall projections, and the estimation of uncertainties, are better based in the combination of the information provided by an ensemble approach from different RCMs simulations. Taking into account the rainfall variability provided by different RCMs, the aims of this work are to evaluate the performance of two novel approaches based on the reliability ensemble averaging (REA) method for building RCMs ensembles of monthly precipitation over Spain. The proposed methodologies are based on probability density functions (PDFs) considering the variability of different levels of information, on the one hand of annual and seasonal rainfall, and on the other hand of monthly rainfall. The sensitivity of the proposed approaches, to two metrics for identifying the best ensemble building method, is evaluated. The plausible future scenario of rainfall for 2021-2050 over Spain, based on the more robust method, is identified. As a result, the rainfall projections are improved thus decreasing the uncertainties involved, to drive hydrological impacts models and therefore to reduce the cumulative errors in the modeling chain.
Directory of Open Access Journals (Sweden)
Domenico Fuoco
2012-03-01
Full Text Available In order to study and develop an economical solution to environmental pollution in water, a wide variety of materials have been investigated. Natural zeolites emerge from that research as the best in class of this category. Zeolites are natural materials which are relatively abundant and non biodegradable, economical and serve to perform processes of environmental remediation. This paper contains a full description of a new method to characterize the superficial properties of natural zeolites of exotic provenience (Caribbean Islets with atomic force microscopy (AFM. AFM works with the simplicity of the optical microscope and the high resolution typical of a transmission electron microscope (TEM. If the sample is conductive, structural information of mesoporous material is obtained using scanning and transmission electron microscopy (SEM and TEM, otherwise the sample has to be processed through the grafitation technique, but this procedure induces errors of topography. Therefore, the existing AFM method, to observe zeolite powders, is made in a liquid cell-head scanner. This work confirms that it is possible to use an ambient air-head scanner to obtain a new kind of microtopography. Once optimized, this new method will allow investigation of organic micelles, a very soft nanostructure of cetyltriammonium bromide (CTAB, upon an inorganic surface such as natural zeolites. The data also demonstrated some correlation between SEM microphotographies and AFM 3D images.
Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method
Kurashige, Yuki; Nakajima, Takahito; Sato, Takeshi; Hirao, Kimihiko
2010-06-01
We propose an efficient method for evaluating the Coulomb force in the Gaussian and finite-element Coulomb (GFC) method, which is a linear-scaling approach for evaluating the Coulomb matrix and energy in large molecular systems. The efficient evaluation of the analytical gradient in the GFC is not straightforward as well as the evaluation of the energy because the SCF procedure with the Coulomb matrix does not give a variational solution for the Coulomb energy. Thus, an efficient approximate method is alternatively proposed, in which the Coulomb potential is expanded in the Gaussian and finite-element auxiliary functions as done in the GFC. To minimize the error in the gradient not just in the energy, the derived functions of the original auxiliary functions of the GFC are used additionally for the evaluation of the Coulomb gradient. In fact, the use of the derived functions significantly improves the accuracy of this approach. Although these additional auxiliary functions enlarge the size of the discretized Poisson equation and thereby increase the computational cost, it maintains the near linear scaling as the GFC and does not affects the overall efficiency of the GFC approach.
A block-iterative nodal integral method for forced convection problems
International Nuclear Information System (INIS)
A new efficient iterative nodal integral method for the time-dependent two- and three-dimensional incompressible Navier-Stokes equations has been developed. Using the approach introduced by Azmy and Droning to develop nodal mehtods with high accuracy on coarse spatial grids for two-dimensional steady-state problems and extended to coarse two-dimensional space-time grids by Wilson et al. for thermal convection problems, we have developed a new iterative nodal integral method for the time-dependent Navier-Stokes equations for mechanically forced convection. A new, extremely efficient block iterative scheme is employed to invert the Jacobian within each of the Newton-Raphson iterations used to solve the final nonlinear discrete-variable equations. By taking advantage of the special structure of the Jacobian, this scheme greatly reduces memory requirements. The accuracy of the overall method is illustrated by appliying it to the time-dependent version of the classic two-dimensional driven cavity problem of computational fluid dynamics
DEFF Research Database (Denmark)
Babiker, Hassan; Ding, Ming; Overgaard, Søren
2013-01-01
could be affected by the various quality and quantity of bone in the local environment. Thus, implant ﬁxation in one part might differ from the other part of the implant. This study aimed to investigate the inﬂuence of the sampling method on data evaluation. Material and methods: Titanium alloy implants...
Comparative analysis of methods for determining bite force in the spiny dogfish Squalus acanthias.
Huber, Daniel Robert; Motta, Philip Jay
2004-01-01
Many studies have identified relationships between the forces generated by the cranial musculature during feeding and cranial design. Particularly important to understanding the diversity of cranial form amongst vertebrates is knowledge of the generated magnitudes of bite force because of its use as a measure of ecological performance. In order to determine an accurate morphological proxy for bite force in elasmobranchs, theoretical force generation by the quadratomandibularis muscle of the spiny dogfish Squalus acanthias was modeled using a variety of morphological techniques, and lever-ratio analyses were used to determine resultant bite forces. These measures were compared to in vivo bite force measurements obtained with a pressure transducer during tetanic stimulation experiments of the quadratomandibularis. Although no differences were found between the theoretical and in vivo bite forces measured, modeling analyses indicate that the quadratomandibularis muscle should be divided into its constituent divisions and digital images of the cross-sections of these divisions should be used to estimate cross-sectional area when calculating theoretical force production. From all analyses the maximum bite force measured was 19.57 N. This relatively low magnitude of bite force is discussed with respect to the ecomorphology of the feeding mechanism of S. acanthias to demonstrate the interdependence of morphology, ecology, and behavior in organismal design. PMID:14695686
Nesterov, Vladimir
2009-08-01
A nanonewton force facility, based on a disk-pendulum with electrostatic stiffness reduction and electrostatic force compensation, for the measurement of horizontal forces in the range below 1 µN, is presented. It consists of a measuring system and an identical reference system. Recent experiments with the nanonewton force facility have achieved agreement between an electrostatic force and a gravitational force of 80 nN with an uncertainty of less than 3%. A novel method for measurements of the air (vacuum) permittivity at zero frequencies by means of the nanonewton force facility is presented. First measurements in air show a permittivity of the air ɛ ≈ 8.71 × 10-12 F m-1 with an uncertainty of 3%. From a theoretical analysis, it follows that this method can be used for the measurement of the vacuum permittivity ɛ0 at zero frequencies with a relative uncertainty of about 10-5. The precise measurement of the vacuum permittivity ɛ0 for an electrostatic field would be another test for the correctness of Maxwell's equations.
Venema, Victor; Lindau, Ralf
2016-04-01
In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements
Sandage, A; Sandage, Allan
2002-01-01
Please note that this abstract has been shortened from that found in the paper. A brief history is given of the development of the correction for observation selection bias inherent in the calibration of absolute magnitudes using trigonometric parallaxes. As a tutorial to gain an intuitive understanding of several complicated trigonometric bias problems, we study a toy bias model of a parallax catalog which incorporates assumed parallax measuring errors of various severities. The two effects of bias errors on the derived absolute magnitudes are (1) the Lutz-Kelker correction itself that depends on the fractional parallax error and the spatial distribution, and (2) a Malmquist-like `incompleteness' correction of opposite sign due to various apparent magnitude cut-offs as they are progressively imposed on the catalog. The simulations involve 3 million stars spread with varying density distributions in a volume bounded by a radius of 50,000 pc. A fixed absolute magnitude of M_V = +0.6 is used to imitate RR Lyrae...
Parvanova, Sonia
2012-03-01
An idea related to the calculation of stress intensity factors based on the standard appearance of the force-displacement curve is developed in this paper. The presented procedure predicts the shape of the graphics around the point under consideration form where indirectly the stress intensity factors are obtained. The numerical implementation of the new approach is achieved by using element free Galerkin method, which is a variant of meshless methods and requires only nodal data for a domain discretization without a finite element mesh. A MATLAB software code for two dimensional elasticity problems has been worked out, along with intrinsic basis enrichment for precise modelling of the singular stress field around the crack tip. One numerical example of a rectangular plate with different lengths of a symmetric edge crack is portrayed. The stress intensity factors obtained by the present numerical approach are compared with analytical solutions. The errors in the stress intensity factors for opening fracture mode I are less than 1% although the model mesh is relatively coarse.
An adaptive non-raster scanning method in atomic force microscopy for simple sample shapes
International Nuclear Information System (INIS)
It is a significant challenge to reduce the scanning time in atomic force microscopy while retaining imaging quality. In this paper, a novel non-raster scanning method for high-speed imaging is presented. The method proposed here is developed for a specimen with the simple shape of a cell. The image is obtained by scanning the boundary of the specimen at successively increasing heights, creating a set of contours. The scanning speed is increased by employing a combined prediction algorithm, using a weighted prediction from the contours scanned earlier, and from the currently scanned contour. In addition, an adaptive change in the height step after each contour scan is suggested. A rigorous simulation test bed recreates the x–y specimen stage dynamics and the cantilever height control dynamics, so that a detailed parametric comparison of the scanning algorithms is possible. The data from different scanning algorithms are compared after the application of an image interpolation algorithm (the Delaunay interpolation algorithm), which can also run on-line. (paper)
Elvarsson, B. P.; Taylor, L.; Trenkel, Verena; Kupca, V.; Stefansson, G.
2014-01-01
Statistical models of marine ecosystems use a variety of data sources to estimate parameters using composite or weighted likelihood functions with associated weighting issues and questions on how to obtain variance estimates. Regardless of the method used to obtain point estimates, a method is required for variance estimation. A bootstrap technique is introduced for the evaluation of uncertainty in such models, taking into account inherent spatial and temporal correlations in the datasets, wh...
Cartagena, Alexander; Raman, Arvind
2014-01-01
The measurement of viscoelasticity of cells in physiological environments with high spatio-temporal resolution is a key goal in cell mechanobiology. Traditionally only the elastic properties have been measured from quasi-static force-distance curves using the atomic force microscope (AFM). Recently, dynamic AFM-based methods have been proposed to map the local in vitro viscoelastic properties of living cells with nanoscale resolution. However, the differences in viscoelastic properties estima...
Meiklejohn, Kelly A; Faircloth, Brant C; Glenn, Travis C; Kimball, Rebecca T; Braun, Edward L
2016-07-01
Rapid evolutionary radiations are expected to require large amounts of sequence data to resolve. To resolve these types of relationships many systematists believe that it will be necessary to collect data by next-generation sequencing (NGS) and use multispecies coalescent ("species tree") methods. Ultraconserved element (UCE) sequence capture is becoming a popular method to leverage the high throughput of NGS to address problems in vertebrate phylogenetics. Here we examine the performance of UCE data for gallopheasants (true pheasants and allies), a clade that underwent a rapid radiation 10-15 Ma. Relationships among gallopheasant genera have been difficult to establish. We used this rapid radiation to assess the performance of species tree methods, using ∼600 kilobases of DNA sequence data from ∼1500 UCEs. We also integrated information from traditional markers (nuclear intron data from 15 loci and three mitochondrial gene regions). Species tree methods exhibited troubling behavior. Two methods [Maximum Pseudolikelihood for Estimating Species Trees (MP-EST) and Accurate Species TRee ALgorithm (ASTRAL)] appeared to perform optimally when the set of input gene trees was limited to the most variable UCEs, though ASTRAL appeared to be more robust than MP-EST to input trees generated using less variable UCEs. In contrast, the rooted triplet consensus method implemented in Triplec performed better when the largest set of input gene trees was used. We also found that all three species tree methods exhibited a surprising degree of dependence on the program used to estimate input gene trees, suggesting that the details of likelihood calculations (e.g., numerical optimization) are important for loci with limited phylogenetic information. As an alternative to summary species tree methods we explored the performance of SuperMatrix Rooted Triple - Maximum Likelihood (SMRT-ML), a concatenation method that is consistent even when gene trees exhibit topological differences
The Adaptive Buffered Force QM/MM method in the CP2K and AMBER software packages
Mones, Letif; Götz, Andreas W; Laino, Teodoro; Walker, Ross C; Leimkuhler, Ben; Csányi, Gábor; Bernstein, Noam
2014-01-01
The implementation and validation of the adaptive buffered force QM/MM method in two popular packages, CP2K and AMBER are presented. The implementations build on the existing QM/MM functionality in each code, extending it to allow for redefinition of the QM and MM regions during the simulation and reducing QM-MM interface errors by discarding forces near the boundary according to the buffered force-mixing approach. New adaptive thermostats, needed by force-mixing methods, are also implemented. Different variants of the method are benchmarked by simulating the structure of bulk water, water autoprotolysis in the presence of zinc and dimethyl-phosphate hydrolysis using various semiempirical Hamiltonians and density functional theory as the QM model. It is shown that with suitable parameters, based on force convergence tests, the adaptive buffered-force QM/MM scheme can provide an accurate approximation of the structure in the dynamical QM region matching the corresponding fully QM simulations, as well as reprod...
Energy Technology Data Exchange (ETDEWEB)
Maiz, F., E-mail: fethimaiz@gmail.com [University of Cartage, Nabeul Engineering Preparatory Institute, Merazka, 8000 Nabeul (Tunisia); King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413 (Saudi Arabia)
2015-04-15
A novel method to calculate the quantum transmission, resonance and eigenvalue energies forming the sub-bands structure of non-symmetrical, non-periodical semiconducting heterostructure potential has been proposed in this paper. The method can be applied on a multilayer system with varying thickness of the layer and effective mass of electrons and holes. Assuming an approximated effective mass and using Bastard's boundary conditions, Schrödinger equation at each media is solved and then using a confirmed recurrence method, the transmission and reflection coefficients and the energy quantification condition are expressed. They are simple combination of coupled equations. Schrödinger's equation solutions are Airy functions or plane waves, depending on the electrical potential energy slope. To illustrate the feasibility of the proposed method, the N barriers – (N−1) wells structure for N=3, 5, 8, 9, 17 and 35 are studied. All results show very good agreements with previously published results obtained from applying different methods on similar systems.
Pope, Devin G.; Price, Joseph; Wolfers, Justin
2014-01-01
Can raising awareness of racial bias subsequently reduce that bias? We address this question by exploiting the widespread media attention highlighting racial bias among professional basketball referees that occurred in May 2007 following the release of an academic study. Using new data, we confirm that racial bias persisted in the years after the study's original sample, but prior to the media coverage. Subsequent to the media coverage though, the bias completely disappeared. We examine poten...
DEFF Research Database (Denmark)
Silcowitz, Morten; Niebe, Sarah Maria; Erleben, Kenny
2009-01-01
n interactive physical simulation, contact forces are applied to prevent rigid bodies from penetrating each other. Accurate contact force determination is a computationally hard problem. Thus, in practice one trades accuracy for performance. The result is visual artifacts such as viscous or damped...
Anker, Richard
1983-01-01
This article discusses the difficulties involved in obtaining accurate labor force data for Third World women, from the point of view of interviewers, respondents, and labor statisticians or economists. Suggestions are then made regarding alternative definitions of the labor force and survey questionnaire structures in order to overcome some of…
The Modeling Method of Forces Action Based on COADL%基于COADL兵力行动建模方法
Institute of Scientific and Technical Information of China (English)
张磊; 朱琳
2011-01-01
According to the desire of forces action modeling,designing a series of modeling language for forces action- COADL (Course Of Action Description Language), from the description of forces action modeling language,giving the outcome of forces action strategy. And as a basis, discussing the method of forces action modeling which based on COADL, concretely including : forces action basic modeling, phase action modeling, course of action modeling and forces action dynamic model.%根据兵力行动建模的需要,设计了一套兵力行动建模语言--COADL (Course Of Action Description Language),通过对兵力行动建模语言的描述,得到了兵力行动策略的产生,并以此为基础,讨论了基于COADL兵力行动的建模方法,具体包括:基本兵力行动建模,阶段行动方案建模,行动过程建模和兵力行动动态模型的构建.
Directory of Open Access Journals (Sweden)
Khudolii O.N.
2010-08-01
Full Text Available The terms of effective development of force are considered for young gymnasts on the stages of initial and specialized preparation. The models of urgent and moved aside training effect of the power loadings are certain for young gymnasts 7-13 years. It is set that the process of power preparation of young gymnasts can be separate on two stages. On the first stage by means of the concentrated power loadings the expressed decline of force of group of muscles is arrived at. On the second stage by means of favourable a display maximal efforts of loadings the increase of force of group of muscles is arrived at. Application of the power loadings of different orientation is given by possibility during 10-12 employments on 30-60% to increase force of group of muscles, shorten time of training on development of force in two times.
International Nuclear Information System (INIS)
Coarse-grained (CG) models of molecular systems, with fewer mechanical degrees of freedom than an all-atom model, are used extensively in chemical physics. It is generally accepted that a coarse-grained model that accurately describes equilibrium structural properties (as a result of having a well constructed CG potential energy function) does not necessarily exhibit appropriate dynamical behavior when simulated using conservative Hamiltonian dynamics for the CG degrees of freedom on the CG potential energy surface. Attempts to develop accurate CG dynamic models usually focus on replacing Hamiltonian motion by stochastic but Markovian dynamics on that surface, such as Langevin or Brownian dynamics. However, depending on the nature of the system and the extent of the coarse-graining, a Markovian dynamics for the CG degrees of freedom may not be appropriate. In this paper, we consider the problem of constructing dynamic CG models within the context of the Multi-Scale Coarse-graining (MS-CG) method of Voth and coworkers. We propose a method of converting a MS-CG model into a dynamic CG model by adding degrees of freedom to it in the form of a small number of fictitious particles that interact with the CG degrees of freedom in simple ways and that are subject to Langevin forces. The dynamic models are members of a class of nonlinear systems interacting with special heat baths that were studied by Zwanzig [J. Stat. Phys. 9, 215 (1973)]. The properties of the fictitious particles can be inferred from analysis of the dynamics of all-atom simulations of the system of interest. This is analogous to the fact that the MS-CG method generates the CG potential from analysis of equilibrium structures observed in all-atom simulation data. The dynamic models generate a non-Markovian dynamics for the CG degrees of freedom, but they can be easily simulated using standard molecular dynamics programs. We present tests of this method on a series of simple examples that demonstrate that
Energy Technology Data Exchange (ETDEWEB)
Davtyan, Aram; Dama, James F.; Voth, Gregory A. [Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, and Computation Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Andersen, Hans C., E-mail: hca@stanford.edu [Department of Chemistry, Stanford University, Stanford, California 94305 (United States)
2015-04-21
Coarse-grained (CG) models of molecular systems, with fewer mechanical degrees of freedom than an all-atom model, are used extensively in chemical physics. It is generally accepted that a coarse-grained model that accurately describes equilibrium structural properties (as a result of having a well constructed CG potential energy function) does not necessarily exhibit appropriate dynamical behavior when simulated using conservative Hamiltonian dynamics for the CG degrees of freedom on the CG potential energy surface. Attempts to develop accurate CG dynamic models usually focus on replacing Hamiltonian motion by stochastic but Markovian dynamics on that surface, such as Langevin or Brownian dynamics. However, depending on the nature of the system and the extent of the coarse-graining, a Markovian dynamics for the CG degrees of freedom may not be appropriate. In this paper, we consider the problem of constructing dynamic CG models within the context of the Multi-Scale Coarse-graining (MS-CG) method of Voth and coworkers. We propose a method of converting a MS-CG model into a dynamic CG model by adding degrees of freedom to it in the form of a small number of fictitious particles that interact with the CG degrees of freedom in simple ways and that are subject to Langevin forces. The dynamic models are members of a class of nonlinear systems interacting with special heat baths that were studied by Zwanzig [J. Stat. Phys. 9, 215 (1973)]. The properties of the fictitious particles can be inferred from analysis of the dynamics of all-atom simulations of the system of interest. This is analogous to the fact that the MS-CG method generates the CG potential from analysis of equilibrium structures observed in all-atom simulation data. The dynamic models generate a non-Markovian dynamics for the CG degrees of freedom, but they can be easily simulated using standard molecular dynamics programs. We present tests of this method on a series of simple examples that demonstrate that
Comparison of force fields and calculation methods for vibration intervals of isotopic H+3 molecules
International Nuclear Information System (INIS)
This paper reports (a) improved values for low-lying vibration intervals of H+3, H2D+, D2H+, and D+3 calculated using the variational method and Simons--Parr--Finlan representations of the Carney--Porter and Dykstra--Swope ab initio H+3 potential energy surfaces, (b) quartic normal coordinate force fields for isotopic H+3 molecules, (c) comparisons of variational and second-order perturbation theory, and (d) convergence properties of the Lai--Hagstrom internal coordinate vibrational Hamiltonian. Standard deviations between experimental and ab initio fundamental vibration intervals of H+3, H2D+, D2H+, and D+3 for these potential surfaces are 6.9 (Carney--Porter) and 1.2 cm-1 (Dykstra--Swope). The standard deviations between perturbation theory and exact variational fundamentals are 5 and 10 cm-1 for the respective surfaces. The internal coordinate Hamiltonian is found to be less efficient than the previously employed ''t'' coordinate Hamiltonian for these molecules, except in the case of H2D+
Hasan, Md. Sharif; Kayesh, Ruhul; Begum, Farida; Rahman, S. M. Abdur
2016-01-01
The aim of our current research was to synthesize some transition metal complexes of Naproxen, determine their physical properties, and examine their relative stability under various conditions. Characterizations of these complexes were done by 1H-NMR, Differential Scanning Calorimetry (DSC), FT-IR, HPLC, and scanning electron microscope (SEM). Complexes were subjected to acidic, basic, and aqueous hydrolysis as well as oxidation, reduction, and thermal degradation. Also the reversed phase high-performance liquid chromatography (RP-HPLC) method of Naproxen outlined in USP was verified for the Naproxen-metal complexes, with respect to accuracy, precision, solution stability, robustness, and system suitability. The melting points of the complexes were higher than that of the parent drug molecule suggesting their thermal stability. In forced degradation study, complexes were found more stable than the Naproxen itself in all conditions: acidic, basic, oxidation, and reduction media. All the HPLC verification parameters were found within the acceptable value. Therefore, it can be concluded from the study that the metal complexes of Naproxen can be more stable drug entity and offer better efficacy and longer shelf life than the parent Naproxen. PMID:27034891
Hasan, Md Sharif; Kayesh, Ruhul; Begum, Farida; Rahman, S M Abdur
2016-01-01
The aim of our current research was to synthesize some transition metal complexes of Naproxen, determine their physical properties, and examine their relative stability under various conditions. Characterizations of these complexes were done by 1H-NMR, Differential Scanning Calorimetry (DSC), FT-IR, HPLC, and scanning electron microscope (SEM). Complexes were subjected to acidic, basic, and aqueous hydrolysis as well as oxidation, reduction, and thermal degradation. Also the reversed phase high-performance liquid chromatography (RP-HPLC) method of Naproxen outlined in USP was verified for the Naproxen-metal complexes, with respect to accuracy, precision, solution stability, robustness, and system suitability. The melting points of the complexes were higher than that of the parent drug molecule suggesting their thermal stability. In forced degradation study, complexes were found more stable than the Naproxen itself in all conditions: acidic, basic, oxidation, and reduction media. All the HPLC verification parameters were found within the acceptable value. Therefore, it can be concluded from the study that the metal complexes of Naproxen can be more stable drug entity and offer better efficacy and longer shelf life than the parent Naproxen. PMID:27034891
Pre-employment screening and health management for safety forces-methods and techniques.
Mostardi, R A; Porterfield, J A; King, S; Urycki, S
1990-01-01
The purpose of this clinical report is to describe the process by which safety forces (police and fire) are tested prior to employment (pre-employment screening) and the periodic evaluations used to maintain such standards. The process began by testing 350 male police volunteers and developing a series of age stratified norms. These norms are used to compare incoming recruits such that candidates of a given age are compared to norms developed from police officers of the same age. The purposes of this report are to describe the clinical tests used in the pre-employment screening, to report the normative data and to describe the methods of comparing data obtained from applicants to the established norms. The proper management of high risk employees through pre-employment screening and intervention programs has been viewed as being necessary both for the individual employee in reducing injury and disease and for the municipality for cost saving purposes. J Orthop Sports Phys Ther 1990;11(9):398-401. PMID:18787271
Energy Technology Data Exchange (ETDEWEB)
Shiohata, K.; Nemoto, K.; Nagawa, Y.; Sakamoto, S.; Kobayashi, T.; Ito, M.; Koharagi, H. [Hitachi, Ltd, Tokyo (Japan)
1998-11-01
In this analysis method, electromagnetic force calculated by 2-dimensional analysis is transformed into external force for 3-dimensional structural-vibration analysis. And a modeling procedure for a vibrating structure is developed. Further, a space-modal-resonance criteria which relates electromagnetic force to structural-vibration or noise is introduced. In the structural-vibration analysis, the finite element method is used; and in the noise analysis, the boundary element method is used. Finally, vibration and noise of an induction motor are calculated using this criteria. Consequently, high-accuracy modeling is achieved and noise the calculated by the simulation almost coincides with that obtained by experiments. And it is clarified that the-space-modal resonance criteria is effective in numerical simulation. 11 refs., 9 figs., 3 tabs.
An Approximate Method for Calculation of Fluid Force and Response of A Circular Cylinder at Lock-in
Institute of Scientific and Technical Information of China (English)
WANG Yi
2008-01-01
In this paper, equations calculating lift force of a rigid circular cylinder at lock-in in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cylinder at lock-in are deduced based on mode analysis of a multi-degree freedom system. The simplified forms of these equations are also given. Furthermore, an approximate method to predict the forces and response of rigid circular cylinders and long flexible circular cylinders at lock-in is introduced in the case of low mass-damping ratio. A method to eliminate one deficiency of these equations is introduced. Comparison with experimental results shows the effectiveness of this approximate method.
International Nuclear Information System (INIS)
Safety relief valve (SRV) operation creates unsteady reaction forces on the discharge piping due to fluid acceleration. It is important to estimate these forces in order to properly design the piping system and pipe motion restraints. Normally an SRV discharges steam or other gaseous substance. However, the SRV piping design of a nuclear power system may be required to withstand reaction forces caused by the discharge of two-phase steam/water mixtures. The method of characteristics is used to solve both the two-phase and gas flow equations in an SRV piping system. Pipe segment forces for a sample SRV system are presented for cases of steam and water discharge. 5 refs
Goldarag, Firooz Esmaeili; Barzegar, Sajjad; Babaei, Alireza
2015-01-01
In this research, an experimental method for measuring the clamping force as a result of tightening torque in double lap simple bolted and hybrid (bolted-bonded) joints is proposed. Two types of joints, i.e. double lap simple and hybrid (bolted-bonded) joints were prepared for testing. In order to measure the clamping force or pretension resulting from the tightening torque at different applied torques, for both types of joints, a special experimental method was designed using a steel bush th...
DEFF Research Database (Denmark)
Troldborg, Niels; Sørensen, Niels N.; Réthoré, Pierre-Elouan;
2015-01-01
This paper describes a consistent algorithm for eliminating the numerical wiggles appearing when solving the finite volume discretized Navier-Stokes equations with discrete body forces in a collocated grid arrangement. The proposed method is a modification of the Rhie-Chow algorithm where the force...... in a cell is spread on neighboring cells by applying equivalent pressure jumps at the cell faces. The method shows excellent results when applied for simulating the flow through an actuator disk, which is relevant for wind turbine wake simulations. (c) 2015 Elsevier Ltd. All rights reserved....
An Improved Calibration Method for Hydrazine Monitors for the United States Air Force
Energy Technology Data Exchange (ETDEWEB)
Korsah, K
2003-07-07
This report documents the results of Phase 1 of the ''Air Force Hydrazine Detector Characterization and Calibration Project''. A method for calibrating model MDA 7100 hydrazine detectors in the United States Air Force (AF) inventory has been developed. The calibration system consists of a Kintek 491 reference gas generation system, a humidifier/mixer system which combines the dry reference hydrazine gas with humidified diluent or carrier gas to generate the required humidified reference for calibrations, and a gas sampling interface. The Kintek reference gas generation system itself is periodically calibrated using an ORNL-constructed coulometric titration system to verify the hydrazine concentration of the sample atmosphere in the interface module. The Kintek reference gas is then used to calibrate the hydrazine monitors. Thus, coulometric titration is only used to periodically assess the performance of the Kintek reference gas generation system, and is not required for hydrazine monitor calibrations. One advantage of using coulometric titration for verifying the concentration of the reference gas is that it is a primary standard (if used for simple solutions), thereby guaranteeing, in principle, that measurements will be traceable to SI units (i.e., to the mole). The effect of humidity of the reference gas was characterized by using the results of concentrations determined by coulometric titration to develop a humidity correction graph for the Kintek 491 reference gas generation system. Using this calibration method, calibration uncertainty has been reduced by 50% compared to the current method used to calibrate hydrazine monitors in the Air Force inventory and calibration time has also been reduced by more than 20%. Significant findings from studies documented in this report are the following: (1) The Kintek 491 reference gas generation system (generator, humidifier and interface module) can be used to calibrate hydrazine detectors. (2) The
Roche, Laurent; Danieli, Coraline; Belot, Aurélien; Grosclaude, Pascale; Bouvier, Anne-Marie; Velten, Michel; Iwaz, Jean; Remontet, Laurent; Bossard, Nadine
2013-05-15
Net survival, the survival which might occur if cancer was the only cause of death, is a major epidemiological indicator required for international or temporal comparisons. Recent findings have shown that all classical methods used for routine estimation of net survival from cancer-registry data, sometimes called "relative-survival methods," provide biased estimates. Meanwhile, an unbiased estimator, the Pohar-Perme estimator (PPE), was recently proposed. Using real data, we investigated the magnitude of the errors made by four "relative-survival" methods (Ederer I, Hakulinen, Ederer II and a univariable regression model) vs. PPE as reference and examined the influence of time of follow-up, cancer prognosis, and age on the errors made. The data concerned seven cancer sites (2,51,316 cases) collected by FRANCIM cancer registries. Net survivals were estimated at 5, 10 and 15 years postdiagnosis. At 5 years, the errors were generally small. At 10 years, in good-prognosis cancers, the errors made in nonstandardized estimates with all classical methods were generally great (+2.7 to +9% points in prostate cancer) and increased in age-class estimations (vs. 5-year ones). At 15 years, in bad- or average-prognosis cancers, the errors were often substantial whatever the nature of the estimation. In good-prognosis cancers, the errors in nonstandardized estimates of all classical methods were great and sometimes very important. With all classical methods, great errors occurred in age-class estimates resulting in errors in age-standardized estimates (+0.4 to +3.2% points in breast cancer). In estimating net survival, cancer registries should abandon all classical methods and adopt the new Pohar-Perme estimator. PMID:22961565
Energy Technology Data Exchange (ETDEWEB)
Alexeev, A. V.; Maltseva, D. V.; Ivanov, V. A., E-mail: ivanov@polly.phys.msu.ru [Faculty of Physics, Moscow State University, 119991 Moscow (Russian Federation); Klushin, L. I., E-mail: leo@aub.edu.lb [Department of Physics, American University of Beirut, P.O. Box 11-0236, Beirut 1107 2020 (Lebanon); Skvortsov, A. M., E-mail: astarling@yandex.ru [Chemical-Pharmaceutical Academy, Prof. Popova 14, 197022 St. Petersburg (Russian Federation)
2015-04-28
We study force-extension curves of a single semiflexible chain consisting of several rigid rods connected by flexible spacers. The atomic force microscopy and laser optical or magnetic tweezers apparatus stretching these rod-coil macromolecules are discussed. In addition, the stretching by external isotropic force is analyzed. The main attention is focused on computer simulation and analytical results. We demonstrate that the force-extension curves for rod-coil chains composed of two or three rods of equal length differ not only quantitatively but also qualitatively in different probe methods. These curves have an anomalous shape for a chain of two rods. End-to-end distributions of rod-coil chains are calculated by Monte Carlo method and compared with analytical equations. The influence of the spacer’s length on the force-extension curves in different probe methods is analyzed. The results can be useful for interpreting experiments on the stretching of rod-coil block-copolymers.
Institute of Scientific and Technical Information of China (English)
Jim Wang; Sheng-dun Zhao; Hu-shan Shi; Chun-jian Hua
2009-01-01
A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity, the kinematic parameters of the slide, connecting rod and crank were formulated approximately. On the basis of the results above, three inertia forces and the input moment in the mechanism during its idle running were investigated and formulated by dynamic analysis. A verification experiment was performed on a slider-crank mechanism at a high-speed press machine. The forces derived from the established formulas were compared respectively with those obtained by the ADAMS software and the classical method of connecting rod mass substitution. It was experimentally found that the proposed formulas have an improved performance over related earlier techniques. By use of these results, a 1000 kN 1250 rpm four-point high-speed press machine was designed and manufactured. The slide of this press is driven by four sets of slider-crank mechanisms with symmetrical layout and opposite rotation directions to counterbalance the horizontal inertia forces. Four eccentric counterbalance blocks were designed to counterbalance the vertical force after their mass and equivalent eccentric radius were formulated. The high-speed press machine designed by the proposed counterbalance method has worked with satisfactory performance and good dynamic balance for more than four years in practical production.
Design of a piezoresistive triaxial force sensor probe using the sidewall doping method
International Nuclear Information System (INIS)
In this study, we propose a triaxial force measurement sensor probe with piezoresistors fabricated via sidewall doping using rapid thermal diffusion. The device was developed as a tool for measuring micronewton-level forces as vector quantities. The device consists of a 15 µm thick cantilever, two sensing beams and four wiring beams. The length and width of the cantilever are 1240 µm and 140 µm, respectively, with a beam span of 1200 µm and a width of 10–15 µm. The piezoresistors are formed at the root of the cantilever and the sidewalls of the two sensing beams. The sensor spring constants for each axis were measured at kx = 1.5 N m−1, ky = 3.5 N m−1 and kz = 0.64 N m−1. We confirmed that our device was capable of measuring triaxial forces with a minimum detectable force at the submicronewton level. (paper)
Analyses of Levitation Force in Induction Heating Furnace using 3D Edge Finite Element Method
Cingoski, Vlatko; Yamashita, Hideo; Aoi, Tatsufumi
1994-01-01
Induction heating is a very common procedure for melting metals and alloy especially where all other heating procedures are not applicable or advisable. But, design process of such a complicated induction heating devices usually results with extensive use of computer job, time and cost. Not only magnetic flux density and eddy current density distributions inside the furnace have to be analyzed, but also the distribution and intensity of electromagnetic forces, especially levitation force has ...
Approximate Method of Calculating Forces on Rudder During Ship Sailing on a Shipping Route
Directory of Open Access Journals (Sweden)
K. Zelazny
2014-09-01
Full Text Available Service speed of a ship in real weather conditions is a basic design parameter. Forecasting of this speed at preliminary design stage is made difficult by the lack of simple but at the same accurate models of forces acting upon a ship sailing on a preset shipping route. The article presents a model for calculating forces and moment on plane rudder, useful for forecasting of ship service speed at preliminary stages of ship design.
Dielectric Boundary Forces in Numerical Poisson-Boltzmann Methods: Theory and Numerical Strategies
Cai, Qin; Ye, Xiang; Wang, Jun; Luo, Ray
2011-01-01
Continuum modeling of electrostatic interactions based upon the numerical solutions of the Poisson-Boltzmann equation has been widely adopted in biomolecular applications. To extend their applications to molecular dynamics and energy minimization, robust and efficient methodologies to compute solvation forces must be developed. In this study, we have first reviewed the theory for the computation of dielectric boundary forces based on the definition of the Maxwell stress tensor. This is follow...
Tactics, methods and techniques to improve Special Forces in-service enlisted recruiting
Burrell, Robert M.
2002-01-01
This thesis identifies and analyzes recruiting strategies that exist outside of the military service that might be considered to increase the number of high-quality enlisted recruits for the United States Army Special Forces Command (USASFC). The thesis contains a review of the current Special Forces recruiting processes and describes how Special Operations Recruiting Command (SORC) recruits enlisted soldiers. It also analyzes goal congruency and cohesion between SORC, SWCS(A), and USASFC(A)....
Degtiarenko, Pavel V.; Popov, Vladimir E.
2011-03-22
A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.
Siebert, T; Sust, M; Thaller, S; Tilp, M; Wagner, H
2007-04-01
We evaluate an improved method for individually determining neuromuscular properties in vivo. The method is based on Hill's equation used as a force law combined with Newton's equation of motion. To ensure the range of validity of Hill's equation, we first perform detailed investigations on in vitro single muscles. The force-velocity relation determined with the model coincides well with results obtained by standard methods (r=.99) above 20% of the isometric force. In addition, the model-predicted force curves during work loop contractions very well agree with measurements (mean difference: 2-3%). Subsequently, we deduce theoretically under which conditions it is possible to combine several muscles of the human body to model muscles. This leads to a model equation for human leg extension movements containing parameters for the muscle properties and for the activation. To numerically determine these invariant neuromuscular properties we devise an experimental method based on concentric and isometric leg extensions. With this method we determine individual muscle parameters from experiments such that the simulated curves agree well with experiments (r=.99). A reliability test with 12 participants revealed correlations r=.72-.91 for the neuromuscular parameters (p<.01). Predictions of similar movements under different conditions show mean errors of about 5%. In addition, we present applications in sports practise and theory. PMID:17343950
von Nessi, G T
2012-01-01
A new method, based on Bayesian analysis, is presented which unifies the inference of plasma equilibria parameters in a Tokamak with the ability to quantify differences between inferred equilibria and Grad-Shafranov force-balance solutions. At the heart of this technique is the new method of observation splitting, which allows multiple forward models to be associated with a single diagnostic observation. This new idea subsequently provides a means by which the the space of GS solutions can be efficiently characterised via a prior distribution. Moreover, by folding force-balance directly into one set of forward models and utilising simple Biot-Savart responses in another, the Bayesian inference of the plasma parameters itself produces an evidence (a normalisation constant of the inferred posterior distribution) which is sensitive to the relative consistency between both sets of models. This evidence can then be used to help determine the relative accuracy of the tested force-balance model across several discha...
Rashid, Tariq; Shahinpoor, Mohsen
1999-05-01
Ionic polymer platinum composite (IPPC) artificial muscles have been the subject of research activities at AMRI (Artificial Muscle Research Institute) and have been identified as smart intelligent material. The potential for such artificial muscles is so vast that muscles of different enhanced characteristics will be required in the future to accomplish different desired tasks. However the immediate challenges are to identify, control and enhance different desired characteristics of artificial muscles (IPPC). One important milestone that may be regarded, as the most critical one is to enhance force produced by these artificial muscles. Obviously force enhancement if successful may put these artificial muscles into one-to-one competition against the available line of traditional force actuators which fall in the same category. In order to experimentally approach the process of optimizing the force output of ionic polymeric platinum composite (IPPC) artificial muscles, an orthogonal array method was used to identify potential specific manufacturing procedures. These sets of procedures will eventually be helpful to identify the different desired characteristics of manufactured artificial muscles. One manufactured artificial muscles are tested for force outputs, the best ones would then be easily traced back to manufacturing procedure and will be further enhanced up to the desired levels by further refining the underlying manufacturing procedures. The measure chosen for optimization process was basically the force generated by a specific piece of muscle of specific geometry.
Challenges in bias correcting climate change simulations
Maraun, Douglas; Shepherd, Ted; Zappa, Giuseppe; Gutierrez, Jose; Widmann, Martin; Hagemann, Stefan; Richter, Ingo; Soares, Pedro; Mearns, Linda
2016-04-01
Biases in climate model simulations - if these are directly used as input for impact models - will introduce further biases in subsequent impact simulations. In response to this issue, so-called bias correction methods have been developed to post-process climate model output. These methods are now widely used and a crucial component in the generation of high resolution climate change projections. Bias correction is conceptually similar to model output statistics, which has been successfully used for several decades in numerical weather prediction. Yet in climate science, some authors outrightly dismiss any form of bias correction. Starting from this seeming contradiction, we highlight differences between the two contexts and infer consequences and limitations for the applicability of bias correction to climate change projections. We first show that cross validation approaches successfully used to evaluate weather forecasts are fundamentally insufficient to evaluate climate change bias correction. We further demonstrate that different types of model mismatches with observations require different solutions, and some may not sensibly be mitigated. In particular we consider the influence of large-scale circulation biases, biases in the persistence of weather regimes, and regional biases caused by an insufficient representation of the flow-topography interaction. We conclude with a list of recommendations and suggestions for future research to reduce, to post-process, and to cope with climate model biases.
Rolling Force and Rolling Moment in Spline Cold Rolling Using Slip-line Field Method
Institute of Scientific and Technical Information of China (English)
ZHANG Dawei; LI Yongtang; FU Jianhua; ZHENG Quangang
2009-01-01
Rolling force and rolling moment are prime process parameter of external spline cold rolling. However, the precise theoretical formulae of rolling force and rolling moment are still very fewer, and the determination of them depends on experience. In the present study, the mathematical models of rolling force and rolling moment are established based on stress field theory of slip-line. And the isotropic hardening is used to improve the yield criterion. Based on MATLAB program language environment, calculation program is developed according to mathematical models established. The rolling force and rolling moment could be predicted quickly via the calculation program, and then the reliability of the models is validated by FEM. Within the range of module of spline m=0.5-1.5 mm, pressure angle of reference circle α=30.0°-45.0°, and number of spline teeth Z=19-54, the rolling force and rolling moment in rolling process (finishing rolling is excluded) are researched by means of virtualizing orthogonal experiment design. The results of the present study indicate that:the influences of module and number of spline teeth on the maximum rolling force and rolling moment in the process are remarkable;in the case of pressure angle of reference circle is little, module of spline is great, and number of spline teeth is little, the peak value of rolling force in rolling process may appear in the midst of the process;the peak value of rolling moment in rolling process appears in the midst of the process, and then oscillator weaken to a stable value. The results of the present study may provide guidelines for the determination of power of the motor and the design of hydraulic system of special machine, and provide basis for the farther researches on the precise forming process of external spline cold rolling.
Hritz, A. D.; Raymond, T. M.; Dutcher, D. D.
2016-01-01
Accurate estimates of particle surface tension are required for models concerning atmospheric aerosol nucleation and activation. However, it is difficult to collect sufficiently large volumes of atmospheric aerosol for use in typical instruments that measure surface tension, such as goniometers or Wilhelmy plates. In this work, a method that measures the surface tension of collected liquid nanoparticles using atomic force microscopy is presented. A...
International Nuclear Information System (INIS)
The Monte Carlo codes are particularly used at IRSN to simulate the particle transport in complex geometries such as multi-element detectors, voxel phantoms and irradiation facilities. These calculations without any optimisation could run over several CPU days. The biasing methods of TRIPOLI 4.3 or MCNPX 2.4 appear to be very powerful but they require a careful control in order to obtain reliable results. This is why IRSN users of these codes have developed a simple model, i.e. a bunker room, in order to test in terms of CPU time and control difficulty different variance reduction methods proposed by the codes. The geometry of the model is a square room in which there is a neutron isotropic source of UO2, which is typical of the sources simulated in engineering calculations to evaluate the protection shields of the installation facilities. The ceiling, floor and walls are made of concrete. The purpose of the simulation is to calculate the ambient dose equivalent rate outside the room at 20 cm from a wall. The presented results obtained with the two codes are compared with respect to CPU time. (authors)
A Deployment Method Based on Spring Force in Wireless Robot Sensor Networks
Directory of Open Access Journals (Sweden)
Xiangyu Yu
2014-05-01
Full Text Available Robotic sensor deployment is fundamental for the effectiveness of wireless robot sensor networks - a good deployment algorithm leads to good coverage and connectivity with low energy consumption for the whole network. Virtual force-based algorithms (VFAs is one of the most popular approaches to this problem. In VFA, sensors are treated as points subject to repulsive and attractive forces exerted among them - sensors can move according to imaginary force generated in algorithms. In this paper, a virtual spring force-based algorithm with proper damping is proposed for the deployment of sensor nodes in a wireless sensor network (WSN. A new metric called Pair Correlation Diversion (PCD is introduced to evaluate the uniformity of the sensor distribution. Numerical simulations showed that damping can affect the network coverage, energy consumption, convergence time and general topology in the deployment. Moreover, it was found that damping effect (imaginary friction force has significant influence on algortithm outcomes. In addition, when working under approximate critical-damping condition, the proposed approach has the advantage of a higher coverage rate, better configurational uniformity and less energy consumption.
Institute of Scientific and Technical Information of China (English)
杨芃焘; 杨万民; 王妙; 李佳伟; 郭玉霞
2015-01-01
The influence of the width of the middle magnet in the permanent magnet guideways (PMGs) on the levitation force and the levitation height of single-domain yttrium barium copper oxide (YBCO) bulks has been investigated at 77 K under the zero field cooled (ZFC) state. It is found that the largest levitation force can be obtained in the system with the width of the middle magnet of the PMG equal to the size of the YBCO bulk when the gap between the YBCO bulk and PMG is small. Both larger levitation force and higher levitation height can be obtained in the system with the width of the middle magnet of the PMG larger than the size of the YBCO bulk. The stiffness of the levitation force between the PMG and the YBCO bulk is higher in the system with a smaller width of the middle magnet in the PMG. These results provide an effective way to control the levitation force and the levitation height for the superconducting maglev design and applications.
Pork tenderness estimation by taste panel, Warner-Bratzler shear force and on-line methods.
Van Oeckel, M J; Warnants, N; Boucqué, C V
1999-12-01
The extent to which modification of Warner-Bratzler shear force (WBSF) determinations, relating to storage and preparation of the meat, aperture of the V-shaped cutting blade and shearing velocity, improve the relationship with sensory tenderness perception of pork was studied. Additionally four on-line methods: pH1, FOP1 (light scattering), PQM1 (conductivity) and DDLT (Double Density Light Transmission), were evaluated for their ability to predict tenderness. Sensory tenderness evaluation was conducted on 120 frozen (at -18°C for several months) samples of m. longissimus thoracis et lumborum. After overnight thawing, the meat was grilled to an internal temperature of 74°C and scored on an eight-point scale, from extremely tough to extremely tender. The standard WBSF procedure (protocol A) consisted of heating fresh meat samples (stored for 48 h at 4°C post slaughter) at 75°C for 50 min, cooling in cold tap water for 40 min, taking cylindrical cores parallel to the fibre direction, and shearing at a velocity of 200 mm/min with a blade aperture of 60°. For the prediction of sensory tenderness, the WBSF standard procedure (protocol A) showed the lowest variance (R(2)=15%) and the highest standard error of the estimate (SEE=0.97 N) compared to the other WBSF protocols. A decrease in shearing velocity, from 200 to 100 mm/min and, a replacement of the cutting blade with an aperture of 60° by one with an aperture of 30° led to improvements of R(2) (respectively, 19% vs. 13% and 47% vs. 23%) and SEE (respectively, 0.93 N vs. 0.97 N and 0.80 N vs. 0.97 N) and thus were better predictors of tenderness. A blade aperture of 30° instead of 60° also led to considerably lower WBSF values (22.1 N vs. 30.0 N). Freezing, frozen storage and thawing of the meat, prior to WBSF measurement, resulted in higher shear force values (32.7 N vs. 28.7 N) and a better prediction of tenderness, R(2) (25% vs. 15%) and SEE (0.94 N vs. 1.00 N). Furthermore, preparing the frozen stored
Image method in the calculation of the van der Waals force between an atom and a conducting surface
Souza, Reinaldo de Melo e; Sigaud, C; Farina, C
2012-01-01
Initially, we make a detailed historical survey of van der Waals forces, collecting the main references on the subject. Then, we review a method recently proposed by Eberlein and Zietal to compute the dispersion van der Waals interaction between a neutral but polarizable atom and a perfectly conducting surface of arbitrary shape. This method has the advantage of relating the quantum problem to a corresponding classical one in electrostatics so that all one needs is to compute an appropriate Green function. We show how the image method of electrostatics can be conveniently used together with the Eberlein and Zietal mehtod (when the problem admits an image solution). We then illustrate this method in a couple of simple but important cases, including the atom-sphere system. Particularly, in our last example, we present an original result, namely, the van der Waals force between an atom and a boss hat made of a grounded conducting material.
An extended force density method for form finding of constrained cable nets
Directory of Open Access Journals (Sweden)
Ghada Aboul-Nasr
2015-06-01
This paper studied the prestressed cable nets and the loaded cable nets. For prestressed cable nets, coordinate constraints to all nodes of the cable net are introduced to modify the shape after graphically examining the preliminary shape. This preliminary shape resulted from linear analysis of assumed distribution of cable force densities. For analyzing cable nets under different load cases, the first load case is analyzed to achieve the coordinate constraints assigned to nodes. Analysis results are node coordinates, cable forces and lengths. Young’s modulus and areas of cables are used to calculate the unstressed length of all cables using materialization equations, those lengths are used as constraint in the analysis of other load cases. Forces in all cables under different load cases/combinations are calculated. By using this approach, design of cable net under static load is simplified.
A method to transfer distributed Lorentz forces in 3D to a finite element mechanical model
Milanese, A
2011-01-01
The problem of transferring distributed Lorentz forces acting on a coil to a mechanical mesh in 3D is studied. The same analysis was presented a few months ago for the 2D case. Although the physics and the mathematical procedure is the same, the actual details are different enough to be worth being analyzed. With these routines it is possible to perform the magnetic analysis with one tool (for example, ROXIE in 2D, Vector Fields Opera in 3D) and then to project the Lorentz forces on an independent mechanical mesh (for example, in ANSYS). This has the potential to streamline the design of superconducting magnets; a similar analysis strategy is adopted at LBNL. An appendix lists an example of code that can be used to transfer such forces, in an attempt to provide a ready-to-use recipe to the interested engineer.
Calculation Method for Effect of Silt Sediment on Lifting Force of HydraulicGate
Institute of Scientific and Technical Information of China (English)
Gao Shizhao; Xu Guobin; Wang Mingbin
2015-01-01
In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine parti-cles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper putsforward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling(or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accu-racy can meet the need of practical engineering.
Modelling cognitive affective biases in major depressive disorder using rodents.
Hales, Claire A; Stuart, Sarah A; Anderson, Michael H; Robinson, Emma S J
2014-10-01
Major depressive disorder (MDD) affects more than 10% of the population, although our understanding of the underlying aetiology of the disease and how antidepressant drugs act to remediate symptoms is limited. Major obstacles include the lack of availability of good animal models that replicate aspects of the phenotype and tests to assay depression-like behaviour in non-human species. To date, research in rodents has been dominated by two types of assays designed to test for depression-like behaviour: behavioural despair tests, such as the forced swim test, and measures of anhedonia, such as the sucrose preference test. These tests have shown relatively good predictive validity in terms of antidepressant efficacy, but have limited translational validity. Recent developments in clinical research have revealed that cognitive affective biases (CABs) are a key feature of MDD. Through the development of neuropsychological tests to provide objective measures of CAB in humans, we have the opportunity to use 'reverse translation' to develop and evaluate whether similar methods are suitable for research into MDD using animals. The first example of this approach was reported in 2004 where rodents in a putative negative affective state were shown to exhibit pessimistic choices in a judgement bias task. Subsequent work in both judgement bias tests and a novel affective bias task suggest that these types of assay may provide translational methods for studying MDD using animals. This review considers recent work in this area and the pharmacological and translational validity of these new animal models of CABs. PMID:24467454
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity,the kinematic parameters of the slide,connecting rod and crank were formulated approximately. On the basis of the results above,three inertia forces and the input moment in the mechanism during its idle running were investigated and fo...
International Nuclear Information System (INIS)
Analytical methods and test data employed in the core design of bolted joints for the LWBR core are presented. The effects of external working loads, thermal expansion, and material stress relaxation are considered in the formulation developed to analyze joint performance. Extensions of these methods are also provided for bolted joints having both axial and bending flexibilities, and for the effect of plastic deformation on internal forces developed in a bolted joint. Design applications are illustrated by examples
Institute of Scientific and Technical Information of China (English)
2008-01-01
Computational prediction of adsorption of small molecules in porous materials has great impact on the basic and applied research in chemical engineering and material sciences. In this work,we report an approach based on grand canonical ensemble Monte Carlo(GCMC) simulations and ab initio force fields. We calculated the adsorption curves of ammonia in ZSM-5 zeolite and hydrogen in MOF-5(a metal-organic-framework material). The predictions agree well with experimental data. Because the predictions are based on the first principle force fields,this approach can be used for the adsorption prediction of new molecules or materials without experimental data as guidance.
Institute of Scientific and Technical Information of China (English)
罗渝; 许强; 何思明; 李新坡; 何尽川; 吴永
2015-01-01
A new method based on the multi-wedge translation mechanism is presented to calculate the lateral force acting on the stabilizing piles. At first, there is no assumption for the shape of potential sliding surface, it is just considered that the potential sliding surface is a composite of a number of straight lines. And then, the potential sliding mass is divided into a number of triangular wedges take with these straight lines as its base. The kinematic theorem of limit analysis is adopted to calculate the rate of external work and the rate of energy dissipation for each triangular wedge, respectively. Furthermore, the multivariate functions are established to calculate the lateral force acting on the stabilizing piles. The lateral force and the corresponding potential sliding surfaces can be obtained by an optimizational technique. At last, an example is taken to illustrate the method. The effect of soil strength parameters, slope angle and pile roughness on the lateral force and the corresponding potential sliding surface are analyzed. The result are compared with those obtained using other methods.
Directory of Open Access Journals (Sweden)
Nickolas Vlahopoulos
1999-01-01
Full Text Available In this paper a new methodology is presented for applying measured accelerations and forces as excitation on a structural finite element model in order to perform a forced frequency response analysis. The computed vibration constitutes the excitation for an acoustic boundary element analysis. The new developments presented in this paper are associated with: the equivalent force method that can prescribe the acceleration at certain parts of the structure; the integration within a single process of test data that define the excitation, with the vibration analysis, and the acoustic prediction; the utilization of the new technology in simulating the noise radiated from a running engine and determining the effects of design changes. Numerical results for noise radiated from a running engine are compared to test data for a baseline design. The effect of two structural design modifications on the radiated noise is computed, and conclusions are deduced.
Method and system for measuring gate valve clearances and seating force
Casada, Donald A.; Haynes, Howard D.; Moyers, John C.; Stewart, Brian K.
1996-01-01
Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner.
Calibration Methods of Force Control Diagnostic System of A Rolling Stock on the Run
Kolomeets, A.; Bekher, S.
2016-01-01
In article the technique of calibration of system of dynamic control of a rolling stock is described. The scheme of carrying out and the device for calibration of dynamic control of a rolling stock is provided. Dependence of dynamic force on temporary parameters of blow is defined.
Yang, Peng-Tao; Yang, Wan-Min; Wang, Miao; Li, Jia-Wei; Guo, Yu-Xia
2015-11-01
The influence of the width of the middle magnet in the permanent magnet guideways (PMGs) on the levitation force and the levitation height of single-domain yttrium barium copper oxide (YBCO) bulks has been investigated at 77 K under the zero field cooled (ZFC) state. It is found that the largest levitation force can be obtained in the system with the width of the middle magnet of the PMG equal to the size of the YBCO bulk when the gap between the YBCO bulk and PMG is small. Both larger levitation force and higher levitation height can be obtained in the system with the width of the middle magnet of the PMG larger than the size of the YBCO bulk. The stiffness of the levitation force between the PMG and the YBCO bulk is higher in the system with a smaller width of the middle magnet in the PMG. These results provide an effective way to control the levitation force and the levitation height for the superconducting maglev design and applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 51342001 and 50872079), the Key-grant Project of Chinese Ministry of Education (Grant No. 311033), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120202110003), the Innovation Team in Shaanxi Province, China (Grant No. 2014KTC-18), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. GK201101001 and GK201305014), and the Outstanding Doctoral Thesis Foundation Project of Shaanxi Normal University, China (Grant Nos. X2011YB08 and X2012YB05).
Anhysteretic and biased first magnetization curves for Finemet-type toroidal samples
Varga, L. K.; Kovács, Gy.; Takács, J.
The anhysteretic and a set of biased first magnetization (BFMC) curves together with a set of first-order reversal curves (FORC) were measured and modeled by the hyperbolic T( x) model for a Finemet-type nanocrystalline toroidal sample with a round hysteresis loop. Similar to the FORC diagram, a "fingerprint"-like distribution has been obtained from a set of BFMC curves using the mixed second-derivate method of Pike. It is concluded that while the FORC diagram gives the distribution of coercive fields (or Preisach distribution), the BFMC diagram gives the distribution of the critical field where the domain wall magnetization become unstable and split up.
Energy Technology Data Exchange (ETDEWEB)
Valdes Hernandez, Maria del C.; Gonzalez-Castro, Victor; Wang, Xin; Doubal, Fergus; Munoz Maniega, Susana; Wardlaw, Joanna M. [Centre for Clinical Brian Sciences, Department of Neuroimaging Sciences, Edinburgh (United Kingdom); Ghandour, Dina T. [University of Edinburgh, College of Medicine and Veterinary Medicine, Edinburgh (United Kingdom); Armitage, Paul A. [University of Sheffield, Department of Cardiovascular Sciences, Sheffield (United Kingdom)
2016-05-15
Subtle inhomogeneities in the scanner's magnetic fields (B{sub 0} and B{sub 1}) alter the intensity levels of the structural magnetic resonance imaging (MRI) affecting the volumetric assessment of WMH changes. Here, we investigate the influence that (1) correcting the images for the B{sub 1} inhomogeneities (i.e. bias field correction (BFC)) and (2) selection of the WMH change assessment method can have on longitudinal analyses of WMH progression and discuss possible solutions. We used brain structural MRI from 46 mild stroke patients scanned at stroke onset and 3 years later. We tested three BFC approaches: FSL-FAST, N4 and exponentially entropy-driven homomorphic unsharp masking (E{sup 2}D-HUM) and analysed their effect on the measured WMH change. Separately, we tested two methods to assess WMH changes: measuring WMH volumes independently at both time points semi-automatically (MCMxxxVI) and subtracting intensity-normalised FLAIR images at both time points following image gamma correction. We then combined the BFC with the computational method that performed best across the whole sample to assess WMH changes. Analysis of the difference in the variance-to-mean intensity ratio in normal tissue between BFC and uncorrected images and visual inspection showed that all BFC methods altered the WMH appearance and distribution, but FSL-FAST in general performed more consistently across the sample and MRI modalities. The WMH volume change over 3 years obtained with MCMxxxVI with vs. without FSL-FAST BFC did not significantly differ (medians(IQR)(with BFC) = 3.2(6.3) vs. 2.9(7.4)ml (without BFC), p = 0.5), but both differed significantly from the WMH volume change obtained from subtracting post-processed FLAIR images (without BFC)(7.6(8.2)ml, p < 0.001). This latter method considerably inflated the WMH volume change as subtle WMH at baseline that became more intense at follow-up were counted as increase in the volumetric change. Measurement of WMH volume change remains
International Nuclear Information System (INIS)
Subtle inhomogeneities in the scanner's magnetic fields (B0 and B1) alter the intensity levels of the structural magnetic resonance imaging (MRI) affecting the volumetric assessment of WMH changes. Here, we investigate the influence that (1) correcting the images for the B1 inhomogeneities (i.e. bias field correction (BFC)) and (2) selection of the WMH change assessment method can have on longitudinal analyses of WMH progression and discuss possible solutions. We used brain structural MRI from 46 mild stroke patients scanned at stroke onset and 3 years later. We tested three BFC approaches: FSL-FAST, N4 and exponentially entropy-driven homomorphic unsharp masking (E2D-HUM) and analysed their effect on the measured WMH change. Separately, we tested two methods to assess WMH changes: measuring WMH volumes independently at both time points semi-automatically (MCMxxxVI) and subtracting intensity-normalised FLAIR images at both time points following image gamma correction. We then combined the BFC with the computational method that performed best across the whole sample to assess WMH changes. Analysis of the difference in the variance-to-mean intensity ratio in normal tissue between BFC and uncorrected images and visual inspection showed that all BFC methods altered the WMH appearance and distribution, but FSL-FAST in general performed more consistently across the sample and MRI modalities. The WMH volume change over 3 years obtained with MCMxxxVI with vs. without FSL-FAST BFC did not significantly differ (medians(IQR)(with BFC) = 3.2(6.3) vs. 2.9(7.4)ml (without BFC), p = 0.5), but both differed significantly from the WMH volume change obtained from subtracting post-processed FLAIR images (without BFC)(7.6(8.2)ml, p < 0.001). This latter method considerably inflated the WMH volume change as subtle WMH at baseline that became more intense at follow-up were counted as increase in the volumetric change. Measurement of WMH volume change remains challenging. Although
Institute of Scientific and Technical Information of China (English)
周子康; 崔斌
2003-01-01
Based on the adjustment of public financial revenue and expenditure of China according to the international comparable scope, the authors project and research the condition of public financial revenue and expenditure in China by using bias least square method. After the analysis, the authors think that the real public financial capability of China is not as weak as people estimate in advance.
A Single-Vector Force Calibration Method Featuring the Modern Design of Experiments
Parker, P. A.; Morton, M.; Draper, N.; Line, W.
2001-01-01
This paper proposes a new concept in force balance calibration. An overview of the state-of-the-art in force balance calibration is provided with emphasis on both the load application system and the experimental design philosophy. Limitations of current systems are detailed in the areas of data quality and productivity. A unique calibration loading system integrated with formal experimental design techniques has been developed and designated as the Single-Vector Balance Calibration System (SVS). This new concept addresses the limitations of current systems. The development of a quadratic and cubic calibration design is presented. Results from experimental testing are compared and contrasted with conventional calibration systems. Analyses of data are provided that demonstrate the feasibility of this concept and provide new insights into balance calibration.
MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS
Directory of Open Access Journals (Sweden)
Mario Dobrilović
2005-12-01
Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.
MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS
2005-01-01
Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a p...
Zhou, Y.; Ojeda-May, P.; Nagaraju, M.; Pu, J.
2016-01-01
Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path–force matching (RP–FM) has been developed. In RP–FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP–FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639
Zhou, Y; Ojeda-May, P; Nagaraju, M; Pu, J
2016-01-01
Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path-force matching (RP-FM) has been developed. In RP-FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP-FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639
Method and apparatus for adaptive force and position control of manipulators
Seraji, Homayoun (Inventor)
1995-01-01
The described and improved multi-arm invention of this application presents three strategies for adaptive control of cooperative multi-arm robots which coordinate control over a common load. In the position-position control strategy, the adaptive controllers ensure that the end-effector positions of both arms track desired trajectories in Cartesian space despite unknown time-varying interaction forces exerted through a load. In the position-hybrid control strategy, the adaptive controller of one arm controls end-effector motions in the free directions and applied forces in the constraint directions; while the adaptive controller of the other arm ensures that the end-effector tracks desired position trajectories. In the hybrid-hybrid control strategy, the adaptive controllers ensure that both end-effectors track reference position trajectories while simultaneously applying desired forces on the load. In all three control strategies, the cross-coupling effects between the arms are treated as disturbances which are compensated for by the adaptive controllers while following desired commands in a common frame of reference. The adaptive controllers do not require the complex mathematical model of the arm dynamics or any knowledge of the arm dynamic parameters or the load parameters such as mass and stiffness. Circuits in the adaptive feedback and feedforward controllers are varied by novel adaptation laws.
Eri Miura-Fujiwara; Yoshifumi Inaguma; Hisashi Sato; Yoshimi Watanabe
2009-01-01
One of the fabrication methods for functionally graded materials (FGMs) is a centrifugal solid-particle method, which is an application of the centrifugal casting technique. However, it is the difficult to fabricate FGMs containing nano-particles by the centrifugal solid-particle method. Recently, we proposed a novel fabrication method, which we have named the centrifugal mixed-powder method, by which we can obtain FGMs containing nano-particles. Using this processing method, Cu-based FGMs co...
Melsen, L.A.; van Lanen, H. A. J.; N. Wanders; Van Huijgevoort, M. H. J.; Weedon, G.P.
2011-01-01
In this report, two di erent methods to calculate reference evapotranspiration are applied and compared. This has been done in response to inconsistencies among the daily variables in the WATCH Forcing Data (WFD). One method is so-called radiation based (ET0rad), and is the well known Penman-Monteith equation with, among others, incoming short wave radiation as a variable. The radiation-based method used the variables Tair, Tmax and Tmin, Wind, SWdown, LWnet, Qair and PSurf from the WFD. The ...
Observer Biases in the Classroom.
Kite, Mary E.
1991-01-01
Presents three student exercises that demonstrate common perceptual errors described in social psychological literature: actor-observer effect, false consensus bias, and priming effects. Describes methods to be followed and gives terms, sentences, and a story to be used in the exercises. Suggests discussion of the bases and impact of such…
DEFF Research Database (Denmark)
Lynov, Jens-Peter; Bergeron, K.; Coutsias, E.A.;
2000-01-01
We present an efficient spectral method for studies of fundamental vortex dynamics in forced, circular shear flows. The numerical results are compared with results from experiments carried out in rotating flows with both planar and parabolic geometries, Due to the high accuracy of the code, it can...... be determined whether a two-dimensional model is sufficient to describe the experimental results. (C) 2000 IMACS. Published by Elsevier Science B.V. All rights reserved....
Systematic study of even-even nuclei with Hartree-Fock+BCS method using Skyrme SIII force
Energy Technology Data Exchange (ETDEWEB)
Tajima, Naoki; Takahara, Satoshi; Onishi, Naoki [Tokyo Univ. (Japan). Coll. of Arts and Sciences
1997-03-01
We have applied the Hartree-Fock+BCS method with Skyrme SIII force formulated in a three-dimensional Cartesian-mesh representation to even-even nuclei with 2 {<=} Z {<=} 114. We discuss the results concerning the atomic masses, the quadrupole (m=0, 2) and hexadecapole (m=0, 2, 4) deformations, the skin thicknesses, and the halo radii. We also discuss the energy difference between oblate and prolate solutions and the shape difference between protons and neutrons. (author)
Inami, Eiichi; Sugimoto, Yoshiaki
2016-08-01
We propose a new method of extracting electrostatic force. The technique is based on frequency modulation atomic force microscopy (FM-AFM) combined with a voltage pulse. In this method, the work that the electrostatic field does on the oscillating tip is measured through the cantilever energy dissipation. This allows us to directly extract capacitive forces including the longer range part, to which the conventional FM-AFM is insensitive. The distance-dependent contact potential difference, which is modulated by local charges distributed on the surfaces of the tip and/or sample, could also be correctly obtained. In the absence of local charges, our method can perfectly reproduce the electrostatic force as a function of the distance and the bias voltage. Furthermore, we demonstrate that the system serves as a sensitive sensor enabling us to check the existence of the local charges such as trapped charges and patch charges.
Rival, D.; Schoenweitz, D.; Tropea, C.
2009-11-01
It is often very challenging or even impossible to measure the forces directly on swimming or flying animals. For this reason traditional control-volume methods are used to estimate the unsteady forces on the body in question. TR-PIV systems allow for the measurement of the full spatial and temporal velocity field in the control volume as well as along the bounding control surfaces. The corresponding pressure field can be integrated from the complete velocity-field data set. However, the measurement of the velocity field in the proximity of the body’s surface is at times cumbersome due to shadows and reflections. An alternate control-volume formulationfootnotetextJ. Z. Wu, Z.-L. Pan and X.-Y. Lu, ``Unsteady fluid-dynamic force solely in terms of control-surface integral,” Phys. of Fluids 17, 098102 (2005) eliminates the need for velocity measurements in the proximity of the body. This method has been tested and compared to the traditional control-volume technique for a generic pitching and plunging flat plate in a hover chamber. The advantages and disadvantages of these methods are discussed in the context of their measurement accuracy.
Jiang, Shan; Li, Pan; Yu, Yan; Liu, Jun; Yang, Zhiyong
2014-10-17
A thorough understanding of needle-tissue interaction mechanics is necessary to optimize needle design, achieve robotically needle steering, and establish surgical simulation system. It is obvious that the interaction is influenced by numerous variable parameters, which are divided into three categories: needle geometries, insertion methods, and tissue characteristics. A series of experiments are performed to explore the effect of influence factors (material samples n=5 for each factor) on the insertion force. Data were collected from different biological tissues and a special tissue-equivalent phantom with similar mechanical properties, using a 1-DOF mechanical testing system instrumented with a 6-DOF force/torque (F/T) sensor. The experimental results indicate that three basic phases (deformation, insertion, and extraction phase) are existent during needle penetration. Needle diameter (0.7-3.2mm), needle tip (blunt, diamond, conical, and beveled) and bevel angle (10-85°) are turned out to have a great influence on insertion force, so do the insertion velocity (0.5-10mm/s), drive mode (robot-assisted and hand-held), and the insertion process (interrupted and continuous). Different tissues such as skin, muscle, fat, liver capsule and vessel are proved to generate various force cures, which can contribute to the judgement of the needle position and provide efficient insertion strategy. PMID:25169657
Lagrangian bias in the local bias model
International Nuclear Information System (INIS)
It is often assumed that the halo-patch fluctuation field can be written as a Taylor series in the initial Lagrangian dark matter density fluctuation field. We show that if this Lagrangian bias is local, and the initial conditions are Gaussian, then the two-point cross-correlation between halos and mass should be linearly proportional to the mass-mass auto-correlation function. This statement is exact and valid on all scales; there are no higher order contributions, e.g., from terms proportional to products or convolutions of two-point functions, which one might have thought would appear upon truncating the Taylor series of the halo bias function. In addition, the auto-correlation function of locally biased tracers can be written as a Taylor series in the auto-correlation function of the mass; there are no terms involving, e.g., derivatives or convolutions. Moreover, although the leading order coefficient, the linear bias factor of the auto-correlation function is just the square of that for the cross-correlation, it is the same as that obtained from expanding the mean number of halos as a function of the local density only in the large-scale limit. In principle, these relations allow simple tests of whether or not halo bias is indeed local in Lagrangian space. We discuss why things are more complicated in practice. We also discuss our results in light of recent work on the renormalizability of halo bias, demonstrating that it is better to renormalize than not. We use the Lognormal model to illustrate many of our findings
Bias-correction in vector autoregressive models
DEFF Research Database (Denmark)
Engsted, Tom; Pedersen, Thomas Quistgaard
2014-01-01
We analyze the properties of various methods for bias-correcting parameter estimates in both stationary and non-stationary vector autoregressive models. First, we show that two analytical bias formulas from the existing literature are in fact identical. Next, based on a detailed simulation study...... improvement over ordinary least squares. We pay special attention to the risk of pushing an otherwise stationary model into the non-stationary region of the parameter space when correcting for bias. Finally, we consider a recently proposed reduced-bias weighted least squares estimator, and we find that it...
Force and deflection sensor with shell membrane and optical gratings and method of manufacture
Park, Yong-Lae (Inventor); Moslehi, Behzad (Inventor); Black, Richard James (Inventor); Cutkosky, Mark R. (Inventor); Chau, Kelvin K (Inventor)
2011-01-01
A sensor for force is formed from an elastomeric cylinder having a region with apertures. The apertures have passageways formed between them, and an optical fiber is introduced into these passageways, where the optical fiber has a grating for measurement of tension positioned in the passageways between apertures. Optionally, a temperature measurement sensor is placed in or around the elastomer for temperature correction, and if required, a copper film may be deposited in the elastomer for reduced sensitivity to spot temperature variations in the elastomer near the sensors.
Measurement of intrinsic properties of amyloid fibrils by the peak force QNM method
Adamcik, Jozef; Lara, Cecile; Usov, Ivan; Jeong, Jae Sun; Ruggeri, Francesco S.; Dietler, Giovanni; Lashuel, Hilal A.; Hamley, Ian W.; Mezzenga, Raffaele
2012-07-01
We report the investigation of the mechanical properties of different types of amyloid fibrils by the peak force quantitative nanomechanical (PF-QNM) technique. We demonstrate that this technique correctly measures the Young's modulus independent of the polymorphic state and the cross-sectional structural details of the fibrils, and we show that values for amyloid fibrils assembled from heptapeptides, α-synuclein, Aβ(1-42), insulin, β-lactoglobulin, lysozyme, ovalbumin, Tau protein and bovine serum albumin all fall in the range of 2-4 GPa.
Calculation method of efficiency factor in Alford's force
Energy Technology Data Exchange (ETDEWEB)
Ding, X.; Yang, Y.; Chen, W.; Huang, S.; Zheng, C. [Huazhong University of Science and Technology, Wuhan (China). College of Energy and Power Engineering
2006-07-01
The mechanism of gas excitation for wheel eccentricity and to calculate Alford's force are introduced. On the basis of the blade-and-flow parameters a new formulation is derived and validated. The calculation results are consistent with current theory and experimental conclusions. The physical meaning of the ranges of numerical values of the efficiency factor are discussed. This gets rid of the difficulty of selecting the efficiency factor in Alford's formulation and lays a theoretical foundation for the stability analysis to increases turbine rotor stability. (author)
Germano, Fabrizio
2008-01-01
Within the spokes model of Chen and Riordan (2007) that allows for non-localized competition among arbitrary numbers of media outlets, we quantify the effect of concentration of ownership on quality and bias of media content. A main result shows that too few commercial outlets, or better, too few separate owners of commercial outlets can lead to substantial bias in equilibrium. Increasing the number of outlets (commercial and non-commercial) tends to bring down this bias; but the strong...
Jonker, J.B.; Essen, van, A.M.
1997-01-01
A finite element based method has been developed for computing time-averaged fluid-induced radial excitation forces and rotor dynamic forces on a two-dimensional centrifugal impeller rotating and whirling in a volute casing. In this method potential flow theory is used, which implies the assumption of irrotational inviscid flow. In comparison with other analyses of fluid-induced impeller forces, two main features have been included. Firstly, the hydrodynamic interaction between impeller and v...
DEFF Research Database (Denmark)
Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan
2006-01-01
This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model state...... illustrated on a simple one-dimensional groundwater problem. The results show that the presented filters outperform the standard Kalman filter and that the implementations with bias feedback work in more general conditions than the implementations without feedback. 2005 Elsevier Ltd. All rights reserved....
Sertić, Josip; Kozak, Dražan; Samardžić, Ivan
2014-01-01
The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of "Milano" boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized. PMID:24959612
Continuous surface force based lattice Boltzmann equation method for simulating thermocapillary flow
Zheng, Lin; Zheng, Song; Zhai, Qinglan
2016-02-01
In this paper, we extend a lattice Boltzmann equation (LBE) with continuous surface force (CSF) to simulate thermocapillary flows. The model is designed on our previous CSF LBE for athermal two phase flow, in which the interfacial tension forces and the Marangoni stresses as the results of the interface interactions between different phases are described by a conception of CSF. In this model, the sharp interfaces between different phases are separated by a narrow transition layers, and the kinetics and morphology evolution of phase separation would be characterized by an order parameter via Cahn-Hilliard equation which is solved in the frame work of LBE. The scalar convection-diffusion equation for temperature field is resolved by thermal LBE. The models are validated by thermal two layered Poiseuille flow, and two superimposed planar fluids at negligibly small Reynolds and Marangoni numbers for the thermocapillary driven convection, which have analytical solutions for the velocity and temperature. Then thermocapillary migration of two/three dimensional deformable droplet are simulated. Numerical results show that the predictions of present LBE agreed with the analytical solution/other numerical results.
Directory of Open Access Journals (Sweden)
Eri Miura-Fujiwara
2009-12-01
Full Text Available One of the fabrication methods for functionally graded materials (FGMs is a centrifugal solid-particle method, which is an application of the centrifugal casting technique. However, it is the difficult to fabricate FGMs containing nano-particles by the centrifugal solid-particle method. Recently, we proposed a novel fabrication method, which we have named the centrifugal mixed-powder method, by which we can obtain FGMs containing nano-particles. Using this processing method, Cu-based FGMs containing SiC particles and Al-based FGMs containing TiO2 nano-particles on their surfaces have been fabricated. In this article, the microstructure and mechanical property of Cu/SiC and Al/TiO2 FGMs, fabricated by the centrifugal mixed-powder method are reviewed.
Jonker, J.B.; Essen, van T.G.
1997-01-01
A finite element based method has been developed for computing time-averaged fluid-induced radial excitation forces and rotor dynamic forces on a two-dimensional centrifugal impeller rotating and whirling in a volute casing. In this method potential flow theory is used, which implies the assumption
Ramos, A; Talaia, P; Queirós de Melo, F J
2016-01-01
The main goal of this work was to develop an approached model to study dynamic behavior and prediction of the stress distribution in an in vitro Charnley cemented hip arthroplasty. An alternative version of the described pseudo-dynamic procedure is proposed by using the time integration Newmark algorithm. An internal restoring force vector is numerically calculated from the displacement, velocity, and acceleration vectors. A numerical model of hip replacement was developed to analyze the deformation of a dynamically stressed structure for all time steps. The experimental measurement of resulting internal forces generated in the structure (internal restoring force vector) is the second fundamental step of the pseudo-dynamic procedure. These data (as a feedback) are used by the time integration algorithm, which allows updating of the structure's shape for the next displacement, velocity, and acceleration vectors. In the field of Biomechanics, the potentialities of this method contribute to the determination of a dynamically equivalent in vitro stress field of a cemented hip prosthesis; implant fitted in patients with a normal mobility or practice sports. Consequences of the stress distribution in the implant zone that underwent cyclic fatigue loads were also discussed by using a finite element model. Application of this method in Biomechanics appears as a useful tool in the approximate stress field characterization of the peak stress state. Results show a peak value around two times the static situation, more for making possible the prediction of future damage and a programed clinical examination in patients using hip prosthesis. PMID:25483822
Amano, Ken-ichi
2012-01-01
Recent surface force apparatus (SFA) and atomic force microscopy (AFM) can measure force curves between a probe and a sample surface in solvent. The force curve is thought as the solvation structure in some articles, because its shape is generally oscilltive and pitch of the oscillation is about the same as diameter of the solvent. However, it is not the solvation structure. It is only the force between the probe and the sample surface. Therefore, this brief paper presents a method for calculating the solvation structure from the force curve. The method is constructed by using integral equation theory, a statistical mechanics of liquid (Ornstein-Zernike equation coupled by hypernetted-chain closure). This method is considered to be important for elucidation of the solvation structure on a sample surface.
Continuous surface force based lattice Boltzmann equation method for simulating thermocapillary flow
Zheng, Lin; Zhai, Qinglan
2014-01-01
In this paper, we extend a lattice Boltzmann equation (LBE) with continuous surface fore (CSF) to simulate thermocapillary flows. The model is designed on our previous CSF LBE for athermal two phase flow, in which the interfacial tension forces and the Marangoni stresses as the results of the interface interactions between different phases are described by a conception of CSF. In this model, the sharp interfaces between different phases are separated by a narrow transition layers, and the kinetics and morphology evolution of phase separation would be characterized by an order parameter visa Cahn-Hilliard equation which is solved in the frame work of LBE. The scalar convection-diffusion equation for temperature field is also solved by thermal LBE. The models are validated by thermal two layered Poiseuille flow, and a two superimposed planar fluids at negligibly small Reynolds and Marangoni numbers for the thermocapillary driven convection, which have analytical solutions for the velocity and temperature. Then ...
International Nuclear Information System (INIS)
The atomic force microscope (AFM) is widely used for studying the surface morphology and growth of live cells. There are relatively fewer reports on the AFM imaging of yeast cells (Kasas and Ikai, 1995), (Gad and Ikai, 1995). Yeasts have thick and mechanically strong cell walls and are therefore difficult to attach to a solid substrate. In this report, a new immobilization technique for the height mode imaging of living yeast cells in solid media using AFM is presented. The proposed technique allows the cell surface to be almost completely exposed to the environment and studied using AFM. Apart from the new immobilization protocol, for the first time, height mode imaging of live yeast cell surface in intermittent contact mode is presented in this report. Stable and reproducible imaging over a 10-h time span is observed. A significant improvement in operational stability will facilitate the investigation of growth patterns and surface patterns of yeast cells.
Yaghoubi, S.; Shirani, E.; Pishevar, A. R.; Afshar, Y.
2015-04-01
To simulate liquid fluid flows with high Schmidt numbers (Sc), one needs to use a modified version of the Dissipative Particle Dynamics (DPD) method. Recently the modifications made by others for the weight function of dissipative forces, enables DPD simulations for Sc, up to 10. In this paper, we introduce a different dissipative force weight function for DPD simulations that allows achieving a solution with higher values of Sc and improving the dynamic characteristics of the simulating fluid. Moreover, by reducing the energy of DPD particles, even higher values of Sc can be achieved. Finally, using the new proposed weight function and kBT =0.2 , the Sc values can reach up to 200.
Yuan, W.; Li, L.; Zhang, D. G.; Hong, J. Z.
2016-06-01
A flexible beam with large overall rotating motion impacting with a rigid slope is studied in this paper. The tangential friction force caused by the oblique impact is analyzed. The tangential motion of the system is divided into a stick state and a slip state. The contact constraint model and Coulomb friction model are used respectively to deal with the two states. Based on this hybrid modeling method, dynamic equations of the system, which include all states (before, during, and after the collision) are obtained. Simulation results of a concrete example are compared with the results obtained from two other models: a nontangential friction model and a modified Coulomb model. Differences in the results from the three models are discussed. The tangential friction force cannot be ignored when an oblique impact occurs. In addition, the results obtained from the model proposed in this paper are more consistent with real movement.
Assessing the utility of frequency dependent nudging for reducing biases in biogeochemical models
Lagman, Karl B.; Fennel, Katja; Thompson, Keith R.; Bianucci, Laura
2014-09-01
Bias errors, resulting from inaccurate boundary and forcing conditions, incorrect model parameterization, etc. are a common problem in environmental models including biogeochemical ocean models. While it is important to correct bias errors wherever possible, it is unlikely that any environmental model will ever be entirely free of such errors. Hence, methods for bias reduction are necessary. A widely used technique for online bias reduction is nudging, where simulated fields are continuously forced toward observations or a climatology. Nudging is robust and easy to implement, but suppresses high-frequency variability and introduces artificial phase shifts. As a solution to this problem Thompson et al. (2006) introduced frequency dependent nudging where nudging occurs only in prescribed frequency bands, typically centered on the mean and the annual cycle. They showed this method to be effective for eddy resolving ocean circulation models. Here we add a stability term to the previous form of frequency dependent nudging which makes the method more robust for non-linear biological models. Then we assess the utility of frequency dependent nudging for biological models by first applying the method to a simple predator-prey model and then to a 1D ocean biogeochemical model. In both cases we only nudge in two frequency bands centered on the mean and the annual cycle, and then assess how well the variability in higher frequency bands is recovered. We evaluate the effectiveness of frequency dependent nudging in comparison to conventional nudging and find significant improvements with the former.
International Nuclear Information System (INIS)
This documents Phase 1 determinations on sampler induced bias for four sampler types used in tank characterization. Each sampler, grab sampler or bottle-on-a-string, auger sampler, sludge sampler and universal sampler, is briefly discussed and their physical limits noted. Phase 2 of this document will define additional testing and analysis to further define Sampler Bias
Stefanescu, Dan Mihai
2011-01-01
Part I introduces the basic ""Principles and Methods of Force Measurement"" acording to a classification into a dozen of force transducers types: resistive, inductive, capacitive, piezoelectric, electromagnetic, electrodynamic, magnetoelastic, galvanomagnetic (Hall-effect), vibrating wires, (micro)resonators, acoustic and gyroscopic. Two special chapters refer to force balance techniques and to combined methods in force measurement. Part II discusses the ""(Strain Gauge) Force Transducers Components"", evolving from the classical force transducer to the digital / intelligent one, with the inco
Comparison between Mean Forces and Swarms-of-Trajectories String Methods.
Maragliano, Luca; Roux, Benoît; Vanden-Eijnden, Eric
2014-02-11
The original formulation of the string method in collective variable space is compared with a recent variant called string method with swarms-of-trajectories. The assumptions made in the original method are revisited and the significance of the minimum free energy path (MFEP) is discussed in the context of reactive events. These assumptions are compared to those made in the string method with swarms-of-trajectories, and shown to be equivalent in a certain regime: in particular an expression for the path identified by the swarms-of-trajectories method is given and shown to be closely related to the MFEP. Finally, the algorithmic aspects of both methods are compared. PMID:26580029
Compressive force-path method unified ultimate limit-state design of concrete structures
Kotsovos, Michael D
2014-01-01
This book presents a method which simplifies and unifies the design of reinforced concrete (RC) structures and is applicable to any structural element under both normal and seismic loading conditions. The proposed method has a sound theoretical basis and is expressed in a unified form applicable to all structural members, as well as their connections. It is applied in practice through the use of simple failure criteria derived from first principles without the need for calibration through the use of experimental data. The method is capable of predicting not only load-carrying capacity but also the locations and modes of failure, as well as safeguarding the structural performance code requirements. In this book, the concepts underlying the method are first presented for the case of simply supported RC beams. The application of the method is progressively extended so as to cover all common structural elements. For each structural element considered, evidence of the validity of the proposed method is presented t...
Langdon, Jonathan H; Elegbe, Etana; McAleavey, Stephen A
2015-07-01
Single tracking location (STL) shear wave elasticity imaging (SWEI) is a method for detecting elastic differences between tissues. It has the advantage of intrinsic speckle bias suppression compared with multiple tracking location variants of SWEI. However, the assumption of a linear model leads to an overestimation of the shear modulus in viscoelastic media. A new reconstruction technique denoted single tracking location viscosity estimation (STL-VE) is introduced to correct for this overestimation. This technique utilizes the same raw data generated in STL-SWEI imaging. Here, the STL-VE technique is developed by way of a maximum likelihood estimation for general viscoelastic materials. The method is then implemented for the particular case of the Kelvin-Voigt Model. Using simulation data, the STL-VE technique is demonstrated and the performance of the estimator is characterized. Finally, the STL-VE method is used to estimate the viscoelastic parameters of ex vivo bovine liver. We find good agreement between the STL-VE results and the simulation parameters as well as between the liver shear wave data and the modeled data fit. PMID:26168170
Nategholeslam, Mostafa; Gray, C G; Tomberli, Bruno
2014-12-11
We present a new sampling and analysis scheme for calculating the potential of mean force (PMF) of systems studied by steered molecular dynamics simulations. This scheme, which we call the bin-passing method, is based on the forward-reverse (FR) method (due to I. Kosztin and co-workers, Kosztin et al. J. Chem. Phys. 2006, 124(6), 064106) and arguments based on the second law of thermodynamics. Applying the bin-passing method results in enhanced sampling, better separation of the reversible and irreversible work distributions, and faster convergence to the underlying PMF of the system under study. Post-simulation analysis is performed using a purpose-built software that we have made publicly available at https://github.com/1particle/bin-passing_analyzer under the terms of the GNU General Public License (version 3). Three examples are provided, for systems of varying sizes and complexities, to demonstrate the efficiency of this method and the quality of the results: for the dissociation PMF of NaCl in water, the bin-passing method obtains PMFs in excellent agreement with that obtained for the same system and using the same force-field through static (equilibrium) methods. The bin-passing method gives a very symmetric PMF for passage of a single water molecule through a DPPC bilayer, and the resultant PMF leads to permeability values in better agreement with experiments than those obtained through previous simulation studies. Finally, we consider the interaction of the antimicrobial peptide HHC-36 with two model membranes and employ the bin-passing method to obtain the PMFs for peptide adsorption to the membranes. The characteristics of these PMFs are consistent with the qualities established for the HHC-36 peptide through in vivo and in vitro experiments, as a non-toxic strong antimicrobial agent. PMID:25372312
Hritz, Andrew D.; Raymond, Timothy M.; Dutcher, Dabrina D.
2016-08-01
Accurate estimates of particle surface tension are required for models concerning atmospheric aerosol nucleation and activation. However, it is difficult to collect the volumes of atmospheric aerosol required by typical instruments that measure surface tension, such as goniometers or Wilhelmy plates. In this work, a method that measures, ex situ, the surface tension of collected liquid nanoparticles using atomic force microscopy is presented. A film of particles is collected via impaction and is probed using nanoneedle tips with the atomic force microscope. This micro-Wilhelmy method allows for direct measurements of the surface tension of small amounts of sample. This method was verified using liquids, whose surface tensions were known. Particles of ozone oxidized α-pinene, a well-characterized system, were then produced, collected, and analyzed using this method to demonstrate its applicability for liquid aerosol samples. It was determined that oxidized α-pinene particles formed in dry conditions have a surface tension similar to that of pure α-pinene, and oxidized α-pinene particles formed in more humid conditions have a surface tension that is significantly higher.
A method for solving X-ray spectra in laser fusion and a research on ponderomotive force
International Nuclear Information System (INIS)
Two parts are inclued. (1) A method for solving X-ray spectra in laser fusion is presented. In order to solve X-ray spectra in laser fusion, an iterative method with amplitude-limiting and periodic smoothing technique has been developed on the basis of SAND iteration. It has been used to solve the X-ray spectra in laser fusion and some satisfactory results have been obtained. The method is suitable for solving the X-ray spectra from the data of sub-keV X-ray spectrometer, multi-channel K-edge filtering spectrometer and multi-channel filtering fluorescence spectrometer. The computational results show that the numerical instability is suppressed completely, and nonphysical 'negative spectra' and numerical structure in the computed X-ray spectra are eliminated by means of this method. The computational results are independent of the initial trial spectra. (2) Two-dimensional propagation of laser and ponderomotive force are studied. The authors have also studied the two-dimensional laser propagation code HEATER, which has been used in numerical research on absorption rate and radial and axial ponderomotive force with some proper modifications
Bassenne, Maxime; Urzay, Javier; Park, George I.; Moin, Parviz
2016-03-01
This study investigates control-based forcing methods for incompressible homogeneous-isotropic turbulence forced linearly in physical space which result in constant turbulent kinetic energy, constant turbulent dissipation (also constant enstrophy), or a combination of the two based on a least-squares error minimization. The methods consist of proportional controllers embedded in the forcing coefficients. During the transient, the controllers adjust the forcing coefficients such that the controlled quantity achieves very early a minimal relative error with respect to its target stationary value. Comparisons of these forcing methods are made with the non-controlled approaches of Rosales and Meneveau ["Linear forcing in numerical simulations of isotropic turbulence: Physical space implementations and convergence properties," Phys. Fluids 17, 095106 (2005)] and Carroll and Blanquart ["A proposed modification to Lundgren's physical space velocity forcing method for isotropic turbulence," Phys. Fluids 25, 105114 (2013)], using direct numerical simulations (DNS) and large-eddy simulations (LES). The results indicate that the proposed constant-energetics forcing methods shorten the transient period from a user-defined artificial flow field to Navier-Stokes turbulence while maintaining steadier statistics. Additionally, the proposed method of constant kinetic-energy forcing behaves more robustly in coarse LES when initial conditions are employed that favor the occurrence of subgrid-scale backscatter, whereas the other approaches fail to provide physical turbulent flow fields. For illustration, the proposed forcing methods are applied to dilute particle-laden homogeneous-isotropic turbulent flows; the results serve to highlight the influences of the forcing strategies on the disperse-phase statistics.
Phonon excitation and instabilities in biased graphene nanoconstrictions
DEFF Research Database (Denmark)
Gunst, Tue; Lu, Jing Tao; Hedegård, Per;
2013-01-01
We investigate how a high current density perturbs the phonons in a biased graphene nanoconstriction coupled to semi-infinite electrodes. The coupling to electrode phonons, electrode electrons under bias, Joule heating, and current-induced forces is evaluated using first principles density functi...
Magnetization reversal in submicron disks: exchange biased vortices
Sort Viñas, Jordi; Hoffmann, Axel; Chung, S-H.; Buchanan, K. S.; Grimsditch, M.; Baró, M.D.; Dieny, B; Nogués i Sanmiquel, Josep
2005-01-01
Submicron, circular, ferromagnetic-antiferromagnetic dots exhibit different magnetization reversal mechanisms depending on the direction of the magnetic applied field. Shifted, constricted hysteresis loops, typical for vortex formation, are observed for fields along the exchange bias direction. However, for fields applied close to perpendicular to the exchange bias direction, magnetization reversal occurs via coherent rotation. Magnetic force microscopy imaging together with micromagnetic sim...
Driving force analysis of the agricultural water footprint in China based on the LMDI method.
Zhao, Chunfu; Chen, Bin
2014-11-01
China's water scarcity problems have become more severe because of the unprecedented economic development and population explosion. Considering agriculture's large share of water consumption, obtaining a clear understanding of Chinese agricultural consumptive water use plays a key role in addressing China's water resource stress and providing appropriate water mitigation policies. We account for the Chinese agricultural water footprint from 1990 to 2009 based on bottom up approach. Then, the underlying driving forces are decomposed into diet structure effect, efficiency effect, economic activity effect, and population effect, and analyzed by applying a log-mean Divisia index (LMDI) model. The results reveal that the Chinese agricultural water footprint has risen from the 94.1 Gm3 in 1990 to 141 Gm3 in 2009. The economic activity effect is the largest positive contributor to promoting the water footprint growth, followed by the population effect and diet structure effect. Although water efficiency improvement as a significant negative effect has reduced overall water footprint, the water footprint decline from water efficiency improvement cannot compensate for the huge increase from the three positive driving factors. The combination of water efficiency improvement and dietary structure adjustment is the most effective approach for controlling the Chinese agricultural water footprint's further growth. PMID:25289879
Indian Academy of Sciences (India)
Izzet Karakurt
2014-10-01
In this paper, an optimization study was carried out for the cutting force (Fc) acting on circular diamond sawblades in rock sawing. The peripheral speed, traverse speed, cut depth and flow rate of cooling fluid were considered as operating variables and optimized by using Taguchi approach for the Fc. L16(44) orthogonal array was chosen for the experimental trials based on the operating variables and their levels. The signal-to-noise (S/N) ratios and the analysis of variance (ANOVA) were employed to determine optimum cutting conditions and significant operating variables, respectively. The Fc was also modelled based on the operating variables using regression analysis. The developed model was then verified using various statistical approaches. The results revealed that the operating variables of circular diamond sawblades can be precisely optimized by Taguchi approach for the Fc in rock sawing. The cut depth and peripheral speed were statistically determined as the significant operating variables affecting Fc. Furthermore, the modelling results showed that the proposed model can be effectively used for the prediction of Fc in practical applications.
Choi, Min S.; Meshik, Xenia; Mukherjee, Souvik; Farid, Sidra; Doan, Samuel; Covnot, Leigha; Dutta, Mitra; Stroscio, Michael A.
2015-11-01
ZnO quantum dots (QDs) are used in a variety of applications due to several desirable characteristics, including a wide band gap, luminescence, and biocompatibility. Wurtzite ZnO QDs also exhibit a spontaneous polarization along the growth axis, leading to large electric fields. In this work, ZnO QDs around 7 nm in diameter are synthesized using the sol-gel method. Their size and structure are confirmed using photoluminescence, Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. Additionally, electrostatic force microscopy (EFM) is used to measure the amplitude change in the probe which is associated with the electric field produced by ZnO immobilized by layer-by-layer synthesis technique. The measured electrostatic field of 10 8 V/m is comparable to theoretically predicted value. Additionally, the strength of the electrostatic field is shown to depend on the orientation of the QD's c-axis. These results demonstrate a unique technique of quantifying ZnO's electric force using EFM.
Application and investigation of a bound for outcome reporting bias
Gamble Carrol; Williamson Paula R
2007-01-01
Abstract Background Direct empirical evidence for the existence of outcome reporting bias is accumulating and this source of bias is recognised as a potential threat to the validity of meta-analysis of randomised clinical trials. Methods A method for calculating the maximum bias in a meta-analysis due to publication bias is adapted for the setting where within-study selective non-reporting of outcomes is suspected, and compared to the alternative approach of missing data imputation. The prope...
Static Kirchhoff Rods under the Action of External Forces: Integration via Runge-Kutta Method
Directory of Open Access Journals (Sweden)
Ademir L. Xavier Jr.
2014-01-01
at once Kirchhoff and filament reference system equations under appropriate initial boundary conditions. To show the application of the method, we display several numerical solutions for filaments including cases showing the effect of gravity.
Recursive bias estimation for high dimensional regression smoothers
Energy Technology Data Exchange (ETDEWEB)
Hengartner, Nicolas W [Los Alamos National Laboratory; Cornillon, Pierre - Andre [AGROSUP, FRANCE; Matzner - Lober, Eric [UNIV OF RENNES, FRANCE
2009-01-01
In multivariate nonparametric analysis, sparseness of the covariates also called curse of dimensionality, forces one to use large smoothing parameters. This leads to biased smoother. Instead of focusing on optimally selecting the smoothing parameter, we fix it to some reasonably large value to ensure an over-smoothing of the data. The resulting smoother has a small variance but a substantial bias. In this paper, we propose to iteratively correct of the bias initial estimator by an estimate of the latter obtained by smoothing the residuals. We examine in details the convergence of the iterated procedure for classical smoothers and relate our procedure to L{sub 2}-Boosting, For multivariate thin plate spline smoother, we proved that our procedure adapts to the correct and unknown order of smoothness for estimating an unknown function m belonging to H({nu}) (Sobolev space where m should be bigger than d/2). We apply our method to simulated and real data and show that our method compares favorably with existing procedures.
Directory of Open Access Journals (Sweden)
I. I. Sergey
2005-01-01
Full Text Available The paper contains description of a simplified method for calculating closing-in of switch-gear flexible buses at short circuit. The developed method is based on integral and energy principles of mechanics. In order to increase accuracy of the calculation corrections factors are introduced in an explicit formula for calculation of maximum horizontal deviations. These factors have been obtained with the help of a computer program that realized numerical method for calculating closing-in of wires by flexible thread levels.Diagrams are constructed with the purpose to find ymax and criteria of electro-dynamic resistance of flexible buses (permissible impulse of electro-dynamic forces and current of electro-dynamic resistance is determined.
Hamza Fadhila; Azouzi Mohamed Ali; Jarboui Anis
2014-01-01
This paper studies the role of governance mechanisms, CEO‟s cognitive characteristics and firms‟ financial features in justifying the CEO‟s escalatory behavior in firm‟s investment decision. This study aims to provide evidence as to whether managers consider the persuasive influence of governance mechanisms and the firm‟s financial indicators to persevere his initial investment decision while he notes a high level of commitment bias. The proposed model of this paper uses Bayesian Network Meth...
Statistical framework for estimating GNSS bias
Vierinen, Juha; Coster, Anthea J.; Rideout, William C.; Erickson, Philip J.; Norberg, Johannes
2016-03-01
We present a statistical framework for estimating global navigation satellite system (GNSS) non-ionospheric differential time delay bias. The biases are estimated by examining differences of measured line-integrated electron densities (total electron content: TEC) that are scaled to equivalent vertical integrated densities. The spatiotemporal variability, instrumentation-dependent errors, and errors due to inaccurate ionospheric altitude profile assumptions are modeled as structure functions. These structure functions determine how the TEC differences are weighted in the linear least-squares minimization procedure, which is used to produce the bias estimates. A method for automatic detection and removal of outlier measurements that do not fit into a model of receiver bias is also described. The same statistical framework can be used for a single receiver station, but it also scales to a large global network of receivers. In addition to the Global Positioning System (GPS), the method is also applicable to other dual-frequency GNSS systems, such as GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema). The use of the framework is demonstrated in practice through several examples. A specific implementation of the methods presented here is used to compute GPS receiver biases for measurements in the MIT Haystack Madrigal distributed database system. Results of the new algorithm are compared with the current MIT Haystack Observatory MAPGPS (MIT Automated Processing of GPS) bias determination algorithm. The new method is found to produce estimates of receiver bias that have reduced day-to-day variability and more consistent coincident vertical TEC values.
Which forcing data errors matter most when modeling seasonal snowpacks?
Raleigh, M. S.; Lundquist, J. D.; Clark, M. P.
2014-12-01
High quality forcing data are critical when modeling seasonal snowpacks and snowmelt, but their quality is often compromised due to measurement errors or deficiencies in gridded data products (e.g., spatio-temporal interpolation, empirical parameterizations, or numerical weather model outputs). To assess the relative impact of errors in different meteorological forcings, many studies have conducted sensitivity analyses where errors (e.g., bias) are imposed on one forcing at a time and changes in model output are compared. Although straightforward, this approach only considers simplistic error structures and cannot quantify interactions in different meteorological forcing errors (i.e., it assumes a linear system). Here we employ the Sobol' method of global sensitivity analysis, which allows us to test how co-existing errors in six meteorological forcings (i.e., air temperature, precipitation, wind speed, humidity, incoming shortwave and longwave radiation) impact specific modeled snow variables (i.e., peak snow water equivalent, snowmelt rates, and snow disappearance timing). Using the Sobol' framework across a large number of realizations (>100000 simulations annually at each site), we test how (1) the type (e.g., bias vs. random errors), (2) distribution (e.g., uniform vs. normal), and (3) magnitude (e.g., instrument uncertainty vs. field uncertainty) of forcing errors impact key outputs from a physically based snow model (the Utah Energy Balance). We also assess the role of climate by conducting the analysis at sites in maritime, intermountain, continental, and tundra snow zones. For all outputs considered, results show that (1) biases in forcing data are more important than random errors, (2) the choice of error distribution can enhance the importance of specific forcings, and (3) the level of uncertainty considered dictates the relative importance of forcings. While the relative importance of forcings varied with snow variable and climate, the results broadly
B.Satyanarayana; P. Murali Krishna; B. Sreenivasareddy; D. Ramachndran
2012-01-01
A new HPLC method was developed for selective and simultaneous determination of of Teamazepam. The developed method is also applicable for the related substances determination in bulk drugs. The chromatographic separation was achieved on a Zorbax SB C-18, 4.6 x 250mm, and 5µ column. The mobile phase consisted of Acetonitrile and methanol (60:40, v/v) delivered at a flow rate of 2.0 mL min−1. Buffers consisted of dissolve 5.22 g of dipotassium hydrogen orthophosphate in 1000 mL of water and ad...
Photiadou, Christiana; van den Hurk, Bart; van Delden, Aarnout; Weerts, Albrecht
2016-01-01
An adapted statistical bias correction method is introduced to incorporate circulation-dependence of the model precipitation bias, and its influence on estimated discharges for the Rhine basin is analyzed for a historical period. The bias correction method is tailored to time scales relevant to flooding events in the basin. Large-scale circulation patterns (CPs) are obtained through Maximum Covariance Analysis using reanalysis sea level pressure and high-resolution precipitation observations. A bias correction using these CPs is applied to winter and summer separately, acknowledging the seasonal variability of the circulation regimes in North Europe and their correlation with regional precipitation rates over the Rhine basin. Two different climate model ensemble outputs are explored: ESSENCE and CMIP5. The results of the CP-method are then compared to observations and uncorrected model outputs. Results from a simple bias correction based on a delta factor (NoCP-method) are also used for comparison. For both summer and winter, the CP-method offers a statistically significant improvement of precipitation statistics for subsets of data dominated by particular circulation regimes, demonstrating the circulation-dependence of the precipitation bias. Uncorrected, CP and NoCP corrected model outputs were used as forcing to a hydrological model to simulate river discharges. The CP-method leads to a larger improvement in simulated discharge in the Alpine area in winter than in summer due to a stronger dependence of Rhine precipitation on atmospheric circulation in winter. However, the NoCP-method, in comparison to the CP-method, improves the discharge estimations over the entire Rhine basin.
International Nuclear Information System (INIS)
We report a new method for fabrication of Ni nanogaps based on electromigration induced by a field emission current. This method is called “activation” and is demonstrated here using a current source with alternately reversing polarities. The activation procedure with alternating current bias, in which the current source polarity alternates between positive and negative bias conditions, is performed with planar Ni nanogaps defined on SiO2/Si substrates at room temperature. During negative biasing, a Fowler-Nordheim field emission current flows from the source (cathode) to the drain (anode) electrode. The Ni atoms at the tip of the drain electrode are thus activated and then migrate across the gap from the drain to the source electrode. In contrast, in the positive bias case, the field emission current moves the activated atoms from the source to the drain electrode. These two procedures are repeated until the tunnel resistance of the nanogaps is successively reduced from 100 TΩ to 48 kΩ. Scanning electron microscopy and atomic force microscopy studies showed that the gap separation narrowed from approximately 95 nm to less than 10 nm because of the Ni atoms that accumulated at the tips of both the source and drain electrodes. These results show that the alternately biased activation process, which is a newly proposed atom transfer technique, can successfully control the tunnel resistance of the Ni nanogaps and is a suitable method for formation of ultrasmall nanogap structures
Laminar forced convective/conductive heat transfer by finite element method
International Nuclear Information System (INIS)
The present study is directed at developing a finite element computer program for solution of decoupled convective/conductive heat transfer problems. Penalty function formulation has been used to solve momentum equations and subsequently transient energy equation is solved using modified Crank-Nicolson method. The optimal upwinding scheme has been employed in energy equation to remove oscillations at high Peclet number. (author)
Bootstrap bias-adjusted GMM estimators
Ramalho, Joaquim J.S.
2005-01-01
The ability of six alternative bootstrap methods to reduce the bias of GMM parameter estimates is examined in an instrumental variable framework using Monte Carlo analysis. Promising results were found for the two bootstrap estimators suggested in the paper.
International Nuclear Information System (INIS)
Non-empiric calculations of the force field, frequencies of normal oscillations and intensities of oscillations in JR spectrum of LiBH3+ complex ions are performed using the MO lcao SCF method. The alteration of the force field and vibrational spectrum of BH3 molecule is analyzed in the case of its coordination with Li+ cation
Harassment, Bias, and Discrimination.
Welliver, Paul W.
1995-01-01
Discusses a new principle which has been added to the AECT (Association for Educational Communications and Technology) Code of Professional Ethics regarding discrimination, harassment, and bias. An example is presented which illustrates a violation of a professional colleague's rights. (LRW)
DEFF Research Database (Denmark)
Paldam, Martin
censoring: selection by the size of estimate; SR3 selects the optimal combination of fit and size; and SR4 selects the first satisficing result. The last four SRs are steered by priors and result in bias. The MST and the FAT-PET have been developed for detection and correction of such bias. The simulations...... are made by data variation, while the model is the same. It appears that SR0 generates narrow funnels much at odds with observed funnels, while the other four funnels look more realistic. SR1 to SR4 give the mean a substantial bias that confirms the prior causing the bias. The FAT-PET MRA works well...
Introduction to Unconscious Bias
Schmelz, Joan T.
2010-05-01
We all have biases, and we are (for the most part) unaware of them. In general, men and women BOTH unconsciously devalue the contributions of women. This can have a detrimental effect on grant proposals, job applications, and performance reviews. Sociology is way ahead of astronomy in these studies. When evaluating identical application packages, male and female University psychology professors preferred 2:1 to hire "Brian” over "Karen” as an assistant professor. When evaluating a more experienced record (at the point of promotion to tenure), reservations were expressed four times more often when the name was female. This unconscious bias has a repeated negative effect on Karen's career. This talk will introduce the concept of unconscious bias and also give recommendations on how to address it using an example for a faculty search committee. The process of eliminating unconscious bias begins with awareness, then moves to policy and practice, and ends with accountability.
International Nuclear Information System (INIS)
Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied – in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry – neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration
Microfluidic devices, systems, and methods for quantifying particles using centrifugal force
Energy Technology Data Exchange (ETDEWEB)
Schaff, Ulrich Y.; Sommer, Gregory J.; Singh, Anup K.
2015-11-17
Embodiments of the present invention are directed toward microfluidic systems, apparatus, and methods for measuring a quantity of cells in a fluid. Examples include a differential white blood cell measurement using a centrifugal microfluidic system. A method may include introducing a fluid sample containing a quantity of cells into a microfluidic channel defined in part by a substrate. The quantity of cells may be transported toward a detection region defined in part by the substrate, wherein the detection region contains a density media, and wherein the density media has a density lower than a density of the cells and higher than a density of the fluid sample. The substrate may be spun such that at least a portion of the quantity of cells are transported through the density media. Signals may be detected from label moieties affixed to the cells.
Sociometric methods and difference: a force for good - or yet more harm?
Child, Samantha
2012-01-01
This paper offers a critique of sociometrics as a ubiquitous method of measuring social relationships among children in social groups such as school classes. This is important in relation to disability politics and research as the apparently scientific measures are frequently used in the process of labelling children or predisposing the children involved, or others involved with them, to view disabled and other children in particular ways. We open a debate about judgements concerning whether ...
Domenico Fuoco
2012-01-01
In order to study and develop an economical solution to environmental pollution in water, a wide variety of materials have been investigated. Natural zeolites emerge from that research as the best in class of this category. Zeolites are natural materials which are relatively abundant and non biodegradable, economical and serve to perform processes of environmental remediation. This paper contains a full description of a new method to characterize the superficial properties of natural zeolites...
Investigation of Flash Flotation Technology Utilizing Centrifugal Forces and Novel Sparging Methods
Rowley, Dylan Mark
2014-01-01
A new processing technique, centrifugal flotation, has been developed in recent research projects to overcome the large residence times and fine particle limitations of traditional flotation technologies. The major innovation in the area of centrifugal flotation is the Air Sparged Hydrocyclone (ASH), which has proven capabilities in achieving quality products at specific capacities greater than traditional flotation methods. However, the ASH technology ultimately suffers from sparger plugging...
Mishra, Anil V; Umaru B. Conteh
2014-01-01
This paper constructs the float adjusted measure of home bias and explores the determinants of bond home bias by employing the International Monetary Fund's high quality dataset (2001 to 2009) on cross-border bond investment. The paper finds that Australian investors' prefer investing in countries with higher economic development and more developed bond markets. Exchange rate volatility appears to be an impediment for cross-border bond investment. Investors prefer investing in countries with ...
Measuring agricultural policy bias
DEFF Research Database (Denmark)
Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn
2010-01-01
that the agricultural price incentive bias generally perceived to exist during the 1980s was largely eliminated during the 1990s. Results also demonstrate that general equilibrium effects and country-specific characteristics are crucial for determining the sign and magnitude of agricultural bias. Our comprehensive...... protection measure is therefore uniquely suited to capture the full impact of trade policies on relative agricultural price incentives....
Directory of Open Access Journals (Sweden)
Phillips Carl V
2004-08-01
Full Text Available Abstract Background Publication bias, as typically defined, refers to the decreased likelihood of studies' results being published when they are near the null, not statistically significant, or otherwise "less interesting." But choices about how to analyze the data and which results to report create a publication bias within the published results, a bias I label "publication bias in situ" (PBIS. Discussion PBIS may create much greater bias in the literature than traditionally defined publication bias (the failure to publish any result from a study. The causes of PBIS are well known, consisting of various decisions about reporting that are influenced by the data. But its impact is not generally appreciated, and very little attention is devoted to it. What attention there is consists largely of rules for statistical analysis that are impractical and do not actually reduce the bias in reported estimates. PBIS cannot be reduced by statistical tools because it is not fundamentally a problem of statistics, but rather of non-statistical choices and plain language interpretations. PBIS should be recognized as a phenomenon worthy of study – it is extremely common and probably has a huge impact on results reported in the literature – and there should be greater systematic efforts to identify and reduce it. The paper presents examples, including results of a recent HIV vaccine trial, that show how easily PBIS can have a large impact on reported results, as well as how there can be no simple answer to it. Summary PBIS is a major problem, worthy of substantially more attention than it receives. There are ways to reduce the bias, but they are very seldom employed because they are largely unrecognized.
Goodfriend, Marvin
1991-01-01
Aggregation in the presence of data-processing lags distorts the information content of data, violating orthogonality restrictions that hold at the individual level. Though the phenomenon is general, it is illustrated here for the life-cycle-permanent-income model. Cross-section and pooled-panel data induce information-aggregation bias akin to that in aggregate time series. Calculations show that information aggregation can seriously bias tests of the life-cycle model on aggregate time series...
Attention bias modification: the Emperor's new suit?
Directory of Open Access Journals (Sweden)
Emmelkamp Paul MG
2012-06-01
Full Text Available Abstract A series of primarily laboratory-based studies found attention bias modification in socially anxious participants to lead to reduced anxiety. It is argued that the failure to replicate the positive results of attention bias modification in the study of Carlbring et al. may be due to reasons other than the application through the Internet. A number of controlled studies failed to replicate the positive effects of attention bias modification in clinically rather than subclinically socially anxious subjects. Given the lack of robust evidence for attention bias modification in clinically socially anxious individuals, the author is inclined to consider attention bias modification as 'the Emperor's new suit'. Results achieved with regular Internet-based treatments for social anxiety disorder based on cognitive therapy and exposure methods are much better than those achieved with attention bias modification procedures delivered 'face to face' in clinically distressed participants. Given the lack of robust evidence for attention bias modification in clinical samples, there is no need yet to investigate the implementation of attention bias modification through the Internet. Please see related article: http://www.biomedcentral.com/1471-244X/12/66
EVIDENCE OF NATIONALISTIC BIAS IN MUAYTHAI
Directory of Open Access Journals (Sweden)
Tony D. Myers
2006-07-01
Full Text Available MuayThai is a combat sport with a growing international profile but limited research conducted into judging practices and processes. Problems with judging of other subjectively judged combat sports have caused controversy at major international tournaments that have resulted in changes to scoring methods. Nationalistic bias has been central to these problems and has been identified across a range of sports. The aim of this study was to examine nationalistic bias in MuayThai. Data were collected from the International Federation of MuayThai Amateur (IFMA World Championships held in Almaty, Kazakhstan September 2003 and comprised of tournament results from 70 A-class MuayThai bouts each judged by between five and nine judges. Bouts examined featured 62 competitors from 21 countries and 25 judges from 11 countries. Results suggested that nationalistic bias was evident. The bias observed equated to approximately one round difference between opposing judges over the course of a bout (a mean of 1.09 (SE=0.50 points difference between judges with opposing affilations. The number of neutral judges used meant that this level of bias generally did not influence the outcome of bouts. Future research should explore other ingroup biases, such as nearest neighbour bias and political bias as well as investigating the feasibility adopting an electronic scoring system
Biased causal inseparable game
Bhattacharya, Some Sankar
2015-01-01
Here we study the \\emph{causal inseparable} game introduced in [\\href{http://www.nature.com/ncomms/journal/v3/n10/full/ncomms2076.html}{Nat. Commun. {\\bf3}, 1092 (2012)}], but it's biased version. Two separated parties, Alice and Bob, generate biased bits (say input bit) in their respective local laboratories. Bob generates another biased bit (say decision bit) which determines their goal: whether Alice has to guess Bob's bit or vice-verse. Under the assumption that events are ordered with respect to some global causal relation, we show that the success probability of this biased causal game is upper bounded, giving rise to \\emph{biased causal inequality} (BCI). In the \\emph{process matrix} formalism, which is locally in agreement with quantum physics but assume no global causal order, we show that there exist \\emph{inseparable} process matrices that violate the BCI for arbitrary bias in the decision bit. In such scenario we also derive the maximal violation of the BCI under local operations involving tracele...
Zhou, Yu-wei; Zhang, Igor Ying; Wu, Jian-ming; Wu, An-an; Xu, Xin
2011-12-01
Benzene dimer (bz2) is the simplest prototype of the π-π interactions. Such interactions are ubiquitous in diverse areas of science and molecular engineering. In the present work, we have made assessment on some modern density functional methods including B97-D, BLYP-D3, M06-2X, XYG3, and force field models including CHARMM, AMBER, MM3, AMOEBA on six important interaction modes of bz2. Our results not only highlight the usefulness of these cost-effective methods, which can be used as economic substitutes of the expensive CCSD(T) for complex real-world systems, but also indicate their weakness in the description of the π-π interactions, which points to the future direction for further improvements.
International Nuclear Information System (INIS)
We describe a magnetic resonance force microscopy experiment carried out using both a fast-relaxing spin system and a frequency-modulation mode detection method, presenting a validation of the measured signal and sensitivity. The detection method applied along with a self-excited cantilever oscillation worked stably without any serious interference due to spurious cantilever excitation despite application of first-harmonic microwave modulation, and thereby successfully created almost the maximum available signal. The signal could be measured without distortion while the magnetic field was swept at a rate of 1.9 G s-1. The measured sensitivity approached the thermal noise limit of the cantilever with a high quality factor. The experimental results for both signal and noise were in good agreement with theoretical predictions
Janet Gale Stotsky
1996-01-01
This paper examines the nature of gender bias in tax systems. Gender bias takes both explicit and implicit forms. Explicit gender bias is found in many personal income tax systems. Several countries, especially those in Western Europe, have undertaken to eliminate explicit gender bias in recent years. It is more difficult to identify implicit gender bias, since this depends in large part on value judgments as to desirable social and economic behavior. Implicit gender bias has also been a targ...
Delmotte, Blaise; Keaveny, Eric E.; Plouraboué, Franck; Climent, Eric
2015-12-01
We present a new development of the force-coupling method (FCM) to address the accurate simulation of a large number of interacting micro-swimmers. Our approach is based on the squirmer model, which we adapt to the FCM framework, resulting in a method that is suitable for simulating semi-dilute squirmer suspensions. Other effects, such as steric interactions, are considered with our model. We test our method by comparing the velocity field around a single squirmer and the pairwise interactions between two squirmers with exact solutions to the Stokes equations and results given by other numerical methods. We also illustrate our method's ability to describe spheroidal swimmer shapes and biologically-relevant time-dependent swimming gaits. We detail the numerical algorithm used to compute the hydrodynamic coupling between a large collection (104-105) of micro-swimmers. Using this methodology, we investigate the emergence of polar order in a suspension of squirmers and show that for large domains, both the steady-state polar order parameter and the growth rate of instability are independent of system size. These results demonstrate the effectiveness of our approach to achieve near continuum-level results, allowing for better comparison with experimental measurements while complementing and informing continuum models.
Pan, Wenxiao; Bao, Jie; Tartakovsky, Alexandre
2013-11-01
A Continuous Boundary Force (CBF) method was developed for implementing Robin (Navier) boundary condition (BC) that can describe no-slip or slip conditions (slip length from zero to infinity) at the fluid-solid interface. In the CBF method the Robin BC is replaced by a homogeneous Neumann BC and an additional volumetric source term in the governing momentum equation. The formulation is derived based on an approximation of the sharp boundary with a diffuse interface of finite thickness, across which the BC is reformulated by means of a smoothed characteristic function. The CBF method is easy to be implemented in Lagrangian particle-based methods. We first implemented it in smoothed particle hydrodynamics (SPH) to solve numerically the Navier-Stokes equations subject to spatial-independent or dependent Robin BC in two and three dimensions. The numerical accuracy and convergence is examined through comparisons with the corresponding finite difference or finite element solutions. The CBF method is further implemented in smoothed dissipative particle dynamics (SDPD), a mesoscale scheme, for modeling slip flows commonly existent in micro/nano channels and microfluidic devices. The authors acknowledge the funding support by the ASCR Program of the Office of Science, U.S. Department of Energy.
International Nuclear Information System (INIS)
A new method of theoretical simulation for Kelvin probe force microscopy (KPFM) imaging on semiconductor or metal samples is proposed. The method is based on a partitioned real space (PR) density functional based tight binding (DFTB) calculation of the electronic states to determine the multi-pole electro-static force, which is augmented with the chemical force obtained by a perturbation treatment of the orbital hybridization. With the PR-DFTB method, the change of the total energy is calculated together with the induced charge distribution in the tip and the sample by their approach under an applied bias voltage, and the KPFM images, namely the patterns of local contact potential difference (LCPD) distribution, are obtained with the minimum condition of the interaction force. However, since the interaction force is due to electro-static multi-poles, the spatial resolution of the KPFM images obtained by PR-DFTB is limited to the nano-scale range and an atom-scale resolution cannot be attained. By introducing an additional chemical force, i.e., the force due to the orbital hybridization, we succeeded in reproducing atom-scale resolution of KPFM images. Case studies are performed for clean and impurity embedded Si surfaces with Si tip models. (paper)
Probability biases as Bayesian inference
Directory of Open Access Journals (Sweden)
Andre; C. R. Martins
2006-11-01
Full Text Available In this article, I will show how several observed biases in human probabilistic reasoning can be partially explained as good heuristics for making inferences in an environment where probabilities have uncertainties associated to them. Previous results show that the weight functions and the observed violations of coalescing and stochastic dominance can be understood from a Bayesian point of view. We will review those results and see that Bayesian methods should also be used as part of the explanation behind other known biases. That means that, although the observed errors are still errors under the be understood as adaptations to the solution of real life problems. Heuristics that allow fast evaluations and mimic a Bayesian inference would be an evolutionary advantage, since they would give us an efficient way of making decisions. %XX In that sense, it should be no surprise that humans reason with % probability as it has been observed.
Wen, L; Wang, T M; Wu, G H; Liang, J H
2012-09-01
We implement a mackerel (Scomber scombrus) body-shaped robot, programmed to display the three most typical body/caudal fin undulatory kinematics (i.e. anguilliform, carangiform and thunniform), in order to biomimetically investigate hydrodynamic issues not easily tackled experimentally with live fish. The robotic mackerel, mounted on a servo towing system and initially at rest, can determine its self-propelled speed by measuring the external force acting upon it and allowing for the simultaneous measurement of power, flow field and self-propelled speed. Experimental results showed that the robotic swimmer with thunniform kinematics achieved a faster final swimming speed (St = 0.424) relative to those with carangiform (St = 0.43) and anguilliform kinematics (St = 0.55). The thrust efficiency, estimated from a digital particle image velocimetry (DPIV) flow field, showed that the robotic swimmer with thunniform kinematics is more efficient (47.3%) than those with carangiform (31.4%) and anguilliform kinematics (26.6%). Furthermore, the DPIV measurements illustrate that the large-scale characteristics of the flow pattern generated by the robotic swimmer with both anguilliform and carangiform kinematics were wedge-like, double-row wake structures. Additionally, a typical single-row reverse Karman vortex was produced by the robotic swimmer using thunniform kinematics. Finally, we discuss this novel force-feedback-controlled experimental method, and review the relative self-propelled hydrodynamic results of the robot when utilizing the three types of undulatory kinematics. PMID:22556135
澤田, 秀夫
The aerodynamic performance of an AGARD-B model, as an example of a winged model, was measured in a low-speed wind tunnel equipped with the JAXA 60cm Magnetic Suspension and Balance System (MSBS). The flow speed was in the range between 25m/s and 35m/s, and the angle of attack and the yaw angle were in the range of [- 8, 4] and [- 3, 3] degrees, respectively. Six components of the aerodynamic force were evaluated by using the control coil currents of the MSBS. In evaluating the drag, the effect of the lift on the drag must be evaluated at MSBS when the lift is much larger than drag. A new evaluation method for drag and lift was proposed and was examined successfully by subjecting the model to the same loads as in the wind tunnel test. The drag coefficient at zero lift and the derivatives of the lift and pitching moment coefficient with respect to the angle of attack were evaluated and compared with other source data sets. The obtained data agreed well with the corresponding values of the other sources. The side force, yawing moment and rolling moment coefficients were also evaluated on the basis of corresponding calibration test results, and reasonable results were obtained, although they could not be compared due to the lack of reliable data sets.
Caetano, J V; Percin, M; van Oudheusden, B W; Remes, B; de Wagter, C; de Croon, G C H E; de Visser, C C
2015-10-01
An accurate knowledge of the unsteady aerodynamic forces acting on a bio-inspired, flapping-wing micro air vehicle (FWMAV) is crucial in the design development and optimization cycle. Two different types of experimental approaches are often used: determination of forces from position data obtained from external optical tracking during free flight, or direct measurements of forces by attaching the FWMAV to a force transducer in a wind-tunnel. This study compares the quality of the forces obtained from both methods as applied to a 17.4 gram FWMAV capable of controlled flight. A comprehensive analysis of various error sources is performed. The effects of different factors, e.g., measurement errors, error propagation, numerical differentiation, filtering frequency selection, and structural eigenmode interference, are assessed. For the forces obtained from free flight experiments it is shown that a data acquisition frequency below 200 Hz and an accuracy in the position measurements lower than ± 0.2 mm may considerably hinder determination of the unsteady forces. In general, the force component parallel to the fuselage determined by the two methods compares well for identical flight conditions; however, a significant difference was observed for the forces along the stroke plane of the wings. This was found to originate from the restrictions applied by the clamp to the dynamic oscillations observed in free flight and from the structural resonance of the clamped FWMAV structure, which generates loads that cannot be distinguished from the external forces. Furthermore, the clamping position was found to have a pronounced influence on the eigenmodes of the structure, and this effect should be taken into account for accurate force measurements. PMID:26292289
Institute of Scientific and Technical Information of China (English)
YAN XiuFen; JIANG Nan; MA Jing
2009-01-01
A series of theoretical approaches,including conventional FF03 and FF03-based polarization model,as well as the generalized energy-based fragmentation (GEBF) quantum chemistry method,have been applied to investigate the interactions between acetate ion (CH_3COO~-) and the α-subunit of human adult hemoglobin (designated as Hb-α) at four binding sites (Lys16,Lys90,Arg92,and Lys127),respectively.The FF03-based polarizable force fields show that the interaction energies between the CH_3COO~-group and Hb-α follow the trend of Arg92＞Lys127＞Lys90＞Lys16.The complexation of CH_3COO~-with Hb-α is governed by the long-range electrostatic interactions and steric effect.
Energy Technology Data Exchange (ETDEWEB)
Lima, B.L.S. [Laboratório de Sensores Óticos, Escola Politécnica, Universidade de São Paulo, SP (Brazil); Maximino, F.L. [Laboratório de Materiais Magnéticos, Instituto de Física, Universidade de São Paulo, CEP:05314-970 São Paulo, SP (Brazil); Santos, J.C. [Laboratório de Sensores Óticos, Escola Politécnica, Universidade de São Paulo, SP (Brazil); Santos, A.D., E-mail: adsantos@if.usp.br [Laboratório de Materiais Magnéticos, Instituto de Física, Universidade de São Paulo, CEP:05314-970 São Paulo, SP (Brazil)
2015-12-01
This paper presents a method based on the Atomic Force Microscopy technique for direct measurement of magnetostriction coefficient of amorphous Tb–Co films deposited on Si(100) substrate. The magnetostriction coefficient of the film is determined by AFM measuring the deflection of the sample when applying a magnetic field. In order to maximize the deflection of the sample, in-plane magnetic anisotropy was induced by heat treatment under a magnetic field of 5 kOe. The value obtained for the saturation magnetostriction is 204×10{sup −6} for the Tb{sub 23}Co{sub 77} film. - Highlights: • Measurement of magnetostriction coefficient using AFM. • Tb–Co thin films produced by magnetron sputtering. • Magnetostriction characterization of magnetic thin films on nonmagnetic substrates.
International Nuclear Information System (INIS)
This paper presents a method based on the Atomic Force Microscopy technique for direct measurement of magnetostriction coefficient of amorphous Tb–Co films deposited on Si(100) substrate. The magnetostriction coefficient of the film is determined by AFM measuring the deflection of the sample when applying a magnetic field. In order to maximize the deflection of the sample, in-plane magnetic anisotropy was induced by heat treatment under a magnetic field of 5 kOe. The value obtained for the saturation magnetostriction is 204×10−6 for the Tb23Co77 film. - Highlights: • Measurement of magnetostriction coefficient using AFM. • Tb–Co thin films produced by magnetron sputtering. • Magnetostriction characterization of magnetic thin films on nonmagnetic substrates
International Nuclear Information System (INIS)
Non-empirical calculations of equilibrium internuclear distances, force constants, frequencies of normal vibrations, isotope shifts and vibration intensities in IR spectrum of BF3 molecule have been made by MO LCAO SCF method using three bases of grouped gauss functions: DZ (9s5p/4s2p), TZ(10s6p/5s3p) and TZ+P (10s6p1d/5s3p1d). All the three bases lead to the results which are in good agreement with the experimental data. For instance, theoretical values of vibration frequencies differ from the experimental ones by average 3.2; 2.4 and 7.0% in the bases DZ, TZ and TZ+P respectively
Statistical framework for estimating GNSS bias
Vierinen, Juha; Rideout, William C; Erickson, Philip J; Norberg, Johannes
2015-01-01
We present a statistical framework for estimating global navigation satellite system (GNSS) non-ionospheric differential time delay bias. The biases are estimated by examining differences of measured line integrated electron densities (TEC) that are scaled to equivalent vertical integrated densities. The spatio-temporal variability, instrumentation dependent errors, and errors due to inaccurate ionospheric altitude profile assumptions are modeled as structure functions. These structure functions determine how the TEC differences are weighted in the linear least-squares minimization procedure, which is used to produce the bias estimates. A method for automatic detection and removal of outlier measurements that do not fit into a model of receiver bias is also described. The same statistical framework can be used for a single receiver station, but it also scales to a large global network of receivers. In addition to the Global Positioning System (GPS), the method is also applicable to other dual frequency GNSS s...
Bias Modeling for Distantly Supervised Relation Extraction
Directory of Open Access Journals (Sweden)
Yang Xiang
2015-01-01
Full Text Available Distant supervision (DS automatically annotates free text with relation mentions from existing knowledge bases (KBs, providing a way to alleviate the problem of insufficient training data for relation extraction in natural language processing (NLP. However, the heuristic annotation process does not guarantee the correctness of the generated labels, promoting a hot research issue on how to efficiently make use of the noisy training data. In this paper, we model two types of biases to reduce noise: (1 bias-dist to model the relative distance between points (instances and classes (relation centers; (2 bias-reward to model the possibility of each heuristically generated label being incorrect. Based on the biases, we propose three noise tolerant models: MIML-dist, MIML-dist-classify, and MIML-reward, building on top of a state-of-the-art distantly supervised learning algorithm. Experimental evaluations compared with three landmark methods on the KBP dataset validate the effectiveness of the proposed methods.
DEFF Research Database (Denmark)
Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn
The measurement issue is the key issue in the literature on trade policy-induced agri-cultural price incentive bias. This paper introduces a general equilibrium effective rate of protection (GE-ERP) measure, which extends and generalizes earlier partial equilibrium nominal protection measures....... For the 15 sample countries, the results indicate that the agricultural price incentive bias, which was generally perceived to exist during the 1980s, was largely eliminated during the 1990s. The results also demonstrate that general equilibrium effects and country-specific characteristics - including trade...... shares and intersectoral linkages - are crucial for determining the sign and magnitude of trade policy bias. The GE-ERP measure is therefore uniquely suited to capture the full impact of trade policies on agricultural price incentives. A Monte Carlo procedure confirms that the results are robust...
International Nuclear Information System (INIS)
A simple calibration method is described for the determination of surface energy by atomic force microscopy (AFM) pull-off force measurements on nanostructured surfaces covered with molecularly thin liquid films. The method is based on correlating pull-off forces measured in arbitrary units on a nanostructured surface with pull-off forces measured on macroscopically smooth dip-coated gauge surfaces with known surface energy. The method avoids the need for complex calibration of the AFM cantilever stiffness and the determination of the radius of curvature of the AFM tip. Both of the latter measurements are associated with indirect and less accurate measurements of surface energy based on various contact mechanics adhesion models.
Chang, Le; Ishikawa, Takeshi; Kuwata, Kazuo; Takada, Shoji
2013-05-30
Accurate computational estimate of the protein-ligand binding affinity is of central importance in rational drug design. To improve accuracy of the molecular mechanics (MM) force field (FF) for protein-ligand simulations, we use a protein-specific FF derived by the fragment molecular orbital (FMO) method and by the restrained electrostatic potential (RESP) method. Applying this FMO-RESP method to two proteins, dodecin, and lysozyme, we found that protein-specific partial charges tend to differ more significantly from the standard AMBER charges for isolated charged atoms. We did not see the dependence of partial charges on the secondary structure. Computing the binding affinities of dodecin with five ligands by MM PBSA protocol with the FMO-RESP charge set as well as with the standard AMBER charges, we found that the former gives better correlation with experimental affinities than the latter. While, for lysozyme with five ligands, both charge sets gave similar and relatively accurate estimates of binding affinities. PMID:23420697
International Nuclear Information System (INIS)
An accurate experimental method is proposed for on-spot calibration of the measurement sensitivities of multiple micro-cantilever dynamic modes in atomic force microscopy. One of the key techniques devised for this method is a reliable contact detection mechanism that detects the tip-surface contact instantly. At the contact instant, the oscillation amplitude of the tip deflection, converted to that of the deflection signal in laser reading through the measurement sensitivity, exactly equals to the distance between the sample surface and the cantilever base position. Therefore, the proposed method utilizes the recorded oscillation amplitude of the deflection signal and the base position of the cantilever at the contact instant for the measurement sensitivity calibration. Experimental apparatus along with various signal processing and control modules was realized to enable automatic and rapid acquisition of multiple sets of data, with which the calibration of a single dynamic mode could be completed in less than 1 s to suppress the effect of thermal drift and measurement noise. Calibration of the measurement sensitivities of the first and second dynamic modes of three micro-cantilevers having distinct geometries was successfully demonstrated. The dependence of the measurement sensitivity on laser spot location was also experimentally investigated. Finally, an experiment was performed to validate the calibrated measurement sensitivity of the second dynamic mode of a micro-cantilever.
Contextual modulation of biases in face recognition.
Directory of Open Access Journals (Sweden)
Fatima Maria Felisberti
Full Text Available BACKGROUND: The ability to recognize the faces of potential cooperators and cheaters is fundamental to social exchanges, given that cooperation for mutual benefit is expected. Studies addressing biases in face recognition have so far proved inconclusive, with reports of biases towards faces of cheaters, biases towards faces of cooperators, or no biases at all. This study attempts to uncover possible causes underlying such discrepancies. METHODOLOGY AND FINDINGS: Four experiments were designed to investigate biases in face recognition during social exchanges when behavioral descriptors (prosocial, antisocial or neutral embedded in different scenarios were tagged to faces during memorization. Face recognition, measured as accuracy and response latency, was tested with modified yes-no, forced-choice and recall tasks (N = 174. An enhanced recognition of faces tagged with prosocial descriptors was observed when the encoding scenario involved financial transactions and the rules of the social contract were not explicit (experiments 1 and 2. Such bias was eliminated or attenuated by making participants explicitly aware of "cooperative", "cheating" and "neutral/indifferent" behaviors via a pre-test questionnaire and then adding such tags to behavioral descriptors (experiment 3. Further, in a social judgment scenario with descriptors of salient moral behaviors, recognition of antisocial and prosocial faces was similar, but significantly better than neutral faces (experiment 4. CONCLUSION: The results highlight the relevance of descriptors and scenarios of social exchange in face recognition, when the frequency of prosocial and antisocial individuals in a group is similar. Recognition biases towards prosocial faces emerged when descriptors did not state the rules of a social contract or the moral status of a behavior, and they point to the existence of broad and flexible cognitive abilities finely tuned to minor changes in social context.
On System-Dependent Sources of Uncertainty and Bias in Ultrasonic Quantitative Shear-Wave Imaging.
Deng, Yufeng; Rouze, Ned C; Palmeri, Mark L; Nightingale, Kathryn R
2016-03-01
Ultrasonic quantitative shear-wave imaging methods have been developed over the last decade to estimate tissue elasticity by measuring the speed of propagating shear waves following acoustic radiation force excitation. This work discusses eight sources of uncertainty and bias arising from ultrasound system-dependent parameters in ultrasound shear-wave speed (SWS) measurements. Each of the eight sources of error is discussed in the context of a linear, isotropic, elastic, homogeneous medium, combining previously reported analyses with Field II simulations, full-wave 2-D acoustic propagation simulations, and experimental studies. Errors arising from both spatial and temporal sources lead to errors in SWS measurements. Arrival time estimation noise, speckle bias, hardware fluctuations, and phase aberration cause uncertainties (variance) in SWS measurements, while pulse repetition frequency (PRF) and beamforming errors, as well as coupling medium sound speed mismatch, cause biases in SWS measurements (accuracy errors). Calibration of the sources of bias is an important step in the development of shear-wave imaging systems. In a well-calibrated system, where the sources of bias are minimized, and averaging over a region of interest (ROI) is employed to reduce the sources of uncertainty, an SWS error can be expected. PMID:26886980
Anderson, L. R.; Miller, R. D.
1979-01-01
The LOADS computer program L218 which calculates dynamic load coefficient matrices utilizing the force summation method is described. The load equations are derived for a flight vehicle in straight and level flight and excited by gusts and/or control motions. In addition, sensor equations are calculated for use with an active control system. The load coefficient matrices are calculated for the following types of loads: (1) translational and rotational accelerations, velocities, and displacements; (2) panel aerodynamic forces; (3) net panel forces; and (4) shears, bending moments, and torsions.
Institute of Scientific and Technical Information of China (English)
Ma Yingkun; Xie Shilin; Zhang Xinong; Luo Yajun
2013-01-01
A hybrid calibration approach based on support vector machines (SVM) is proposed to characterize nonlinear cross coupling of multi-dimensional transducer.It is difficult to identify these unknown nonlinearities and crosstalk just with a single conventional calibration approach.In this paper,a hybrid model comprising calibration matrix and SVM model for calibrating linearity and nonlinearity respectively is built up.The calibration matrix is determined by linear artificial neural network (ANN),and the SVM is used to compensate for the nonlinear cross coupling among each dimension.A simulation of the calibration of a multi-dimensional sensor is conducted by the SVM hybrid calibration method,which is then utilized to calibrate a six-component force/torque transducer of wind tunnel balance.From the calibrating results,it can be indicated that the SVM hybrid calibration method has improved the calibration accuracy significantly without increasing data samples,compared with calibration matrix.Moreover,with the calibration matrix,the hybrid model can provide a basis for the design of transducers.
Wijk, van, M.J.; Krut, S.; Pierrot, F.; J. L. Herder
2011-01-01
This paper proposes a generic method for deriving the general shaking force balance conditions of parallel manipulators. Instead of considering the balancing of a parallel manipulator link-by-link or leg-by-leg, the architecture is considered altogether. The first step is to write the linear momentum of each element. The second step is to substitute the derivatives of the loop equations, by which the general force balance conditions are obtained. Subsequently specific kinematic conditions are...
Li, R.; Wang, S.-Y.; Gillies, R. R.
2016-04-01
Large biases associated with climate projections are problematic when it comes to their regional application in the assessment of water resources and ecosystems. Here, we demonstrate a method that can reduce systematic biases in regional climate projections. The global and regional climate models employed to demonstrate the technique are the Community Climate System Model (CCSM) and the Weather Research and Forecasting (WRF) model. The method first utilized a statistical regression technique and a global reanalysis dataset to correct biases in the CCSM-simulated variables (e.g., temperature, geopotential height, specific humidity, and winds) that are subsequently used to drive the WRF model. The WRF simulations were conducted for the western United States and were driven with (a) global reanalysis, (b) original CCSM, and (c) bias-corrected CCSM data. The bias-corrected CCSM data led to a more realistic regional climate simulation of precipitation and associated atmospheric dynamics, as well as snow water equivalent (SWE), in comparison to the original CCSM-driven WRF simulation. Since most climate applications rely on existing global model output as the forcing data (i.e., they cannot re-run or change the global model), which often contain large biases, this method provides an effective and economical tool to reduce biases in regional climate downscaling simulations of water resource variables.
Directory of Open Access Journals (Sweden)
Dirk Reith
2013-09-01
Full Text Available Molecular modeling is an important subdomain in the field of computational modeling, regarding both scientific and industrial applications. This is because computer simulations on a molecular level are a virtuous instrument to study the impact of microscopic on macroscopic phenomena. Accurate molecular models are indispensable for such simulations in order to predict physical target observables, like density, pressure, diffusion coefficients or energetic properties, quantitatively over a wide range of temperatures. Thereby, molecular interactions are described mathematically by force fields. The mathematical description includes parameters for both intramolecular and intermolecular interactions. While intramolecular force field parameters can be determined by quantum mechanics, the parameterization of the intermolecular part is often tedious. Recently, an empirical procedure, based on the minimization of a loss function between simulated and experimental physical properties, was published by the authors. Thereby, efficient gradient-based numerical optimization algorithms were used. However, empirical force field optimization is inhibited by the two following central issues appearing in molecular simulations: firstly, they are extremely time-consuming, even on modern and high-performance computer clusters, and secondly, simulation data is affected by statistical noise. The latter provokes the fact that an accurate computation of gradients or Hessians is nearly impossible close to a local or global minimum, mainly because the loss function is flat. Therefore, the question arises of whether to apply a derivative-free method approximating the loss function by an appropriate model function. In this paper, a new Sparse Grid-based Optimization Workflow (SpaGrOW is presented, which accomplishes this task robustly and, at the same time, keeps the number of time-consuming simulations relatively small. This is achieved by an efficient sampling procedure
Institute of Scientific and Technical Information of China (English)
张伟; 荣伟彬; 王乐锋; 路遥; 孙立宁
2015-01-01
针对保偏光纤耦合器熔融拉锥制造过程中拉力控制问题,提出一种新的计算机在线拉力控制方法. 拉力控制系统由计算机、拉伸机构、圆光栅及控制电路组成,通过检测光纤支架的旋转角度、改变线圈中的电流,控制永磁铁与线圈间的电磁力,实现对拉伸力的实时控制. 分析电磁力和拉力的关系,建立永磁铁和线圈的三维有限元模型,确定永磁铁的运动轨迹,并对通电线圈的磁场分布和电磁力进行仿真,得到线圈中的电流、支架旋转角度和拉力的关系式. 仿真结果表明拉力控制良好,控制误差约为1.03%.%According to the problem of drawing force control in the fused biconical tapering process of polarization maintaining fiber ( PMF ) coupler, an online computer control method of drawing force is presented, which includes the computer, drawing mechanism, rotary position encoders and a control circuit. By detecting the rotation angle of fiber clamp, the electro-magnetic force can be controlled through changing the coil current, and the real-time control of drawing force is realized. Firstly, the relationship between the electromagnetic force and drawing force is analyzed, a 3D finite element model of the permanent magnet and the coil is established, and a trajectory equation describing the permanent magnet is obtained. Then, by simulation of the magnetic field and the electro-magnetic force around the coil, the relationship among the coil current, the rotation angle of fiber clamp and the drawing force is determined. At last, by simulation, the drawing force is controlled within an error of 1.03%.
Mei, Chuh; Shen, Mo-How
1987-01-01
Multiple-mode nonlinear forced vibration of a beam was analyzed by the finite element method. Inplane (longitudinal) displacement and inertia (IDI) are considered in the formulation. By combining the finite element method and nonlinear theory, more realistic models of structural response are obtained more easily and faster.
Equivalent body-force model for magnetostrictive transduction in EMATs
Nagy, Peter B.; Ribichini, Remo
2015-03-01
Electromagnetic Acoustic Transducers (EMATs) are an attractive alternative to standard piezoelectric probes in those applications where couplant fluid cannot be used, i.e. high speed or high temperature testing, or when specific wave-modes have to be excited. When used on ferromagnetic samples, EMATs generate elastic waves through three different transduction mechanisms: the Lorentz force, the magnetization force and magnetostriction. The modeling of such phenomena has drawn the attention of several researchers, leading to different physical formalizations, especially for magnetostriction, being the most complex mechanism. This work presents a physics-based model for tangential bias field magnetostrictive EMATs employing surface tractions equivalent to the inertia body forces caused by magnetostrictive strains. This type of modeling had been previously used to validate a Finite Element model for normal bias field EMATs and here is extended to the tangential bias field configuration. Moreover, it is shown that the proposed model is equivalent to a recently developed method using the spatial convolution integral of body forces with Green's tensor to model elastic wave generation in a solid half-space.
Directory of Open Access Journals (Sweden)
Yan-yang Wang
2014-01-01
Full Text Available The vibration of SRM obtains less attention for in-wheel motor applications according to the present research works. In this paper, the vertical component of SRM unbalanced radial force, which is named as SRM vertical force, is taken into account in suspension performance for in-wheel motor driven electric vehicles (IWM-EV. The analysis results suggest that SRM vertical force has a great effect on suspension performance. The direct cause for this phenomenon is that SRM vertical force is directly exerted on the wheel, which will result in great variation in tyre dynamic load and the tyre will easily jump off the ground. Furthermore, the frequency of SRM vertical force is broad which covers the suspension resonance frequencies. So it is easy to arouse suspension resonance and greatly damage suspension performance. Aiming at the new problem, FxLMS (filtered-X least mean square controller is proposed to improve suspension performance. The FxLMS controller is based on active suspension system which can generate the controllable force to suppress the vibration caused by SRM vertical force. The conclusion shows that it is effective to take advantage of active suspensions to reduce the effect of SRM vertical force on suspension performance.
Dujmovic, Vida; Morin, Pat
2008-01-01
A data structure, called a biased range tree, is presented that preprocesses a set S of n points in R^2 and a query distribution D for 2-sided orthogonal range counting queries. The expected query time for this data structure, when queries are drawn according to D, matches, to within a constant factor, that of the optimal decision tree for S and D. The memory and preprocessing requirements of the data structure are O(n log n).
Kadelbach, Irmgard
2003-01-01
Die Elektrocochleographie (EcoG) ist eine der vielversprechendsten Methoden, cochleäre Dysfunktionen mit objektiver Diagnostik zu verifizieren. Erweitert durch das Prinzip des Biasings, also der gleichzeitigen Präsentation von Testtönen in einen niederfrequenten 52-Hz-Sinusdauerton, läßt sich die Funktion der Cochlea und eine möglicherweise pathologische Arbeitsweise aufdecken. In der Auswertung der Amplituden des Summationspotentials (SP), des cochleären Mikrophonpotentials (CM) und des Summ...
Photoconductivity of biased graphene
Freitag, Marcus; Low, Tony; Xia, Fengnian; Avouris, Phaedon
2012-01-01
Graphene is a promising candidate for optoelectronic applications such as photodetectors, terahertz imagers, and plasmonic devices. The origin of photoresponse in graphene junctions has been studied extensively and is attributed to either thermoelectric or photovoltaic effects. In addition, hot carrier transport and carrier multiplication are thought to play an important role. Here we report the intrinsic photoresponse in biased but otherwise homogeneous graphene. In this classic photoconduct...
Orum, Aslihan; Takatori, Kazumasa; Hori, Shigeo; Ikeda, Tomiko; Yoshimura, Masamichi; Tani, Toshihiko
2016-08-01
Rectangular platelike particles of La2Ti2O7, a layered perovskite, were synthesized in KCl, NaCl, and LiCl by the molten flux method. The formation mechanism of the equilibrium shape in these alkali chloride fluxes was discussed in terms of the surface and interfacial energies of crystallographic planes. The atomic force microscopy (AFM) observations revealed that the developed plane of the platelike particles is along the interlayers in the {110}-type layered crystal structure, and is considered to represent the lowest surface energy plane in which strong, periodic Ti–O bond chains terminate. Herein, for the first time, a growth mechanism for La2Ti2O7 particles is proposed and discussed. Triangular prism structures along the c-axis were observed on the developed planes of KCl-grown particles whereas no such structures were found on those of LiCl-grown ones. AFM measurements suggest that the prism facets are {210}-La2Ti2O7, which results in lower interfacial energy within KCl.
International Nuclear Information System (INIS)
Highlights: • We propose and develop the LMDI approach to factorize changes in electricity bill vulnerability. • Spanish vulnerability (1995–2011) markedly grew mainly by increasing gas dependence. • Fuel price increase and growing importance of electricity damage energy security. • Energy intensity advances & fuel diversification: insufficient to drive vulnerability. • Main recommendation: enhance internal energy market and common external EU strategy. - Abstract: High energy dependence on fossil raises vulnerability concerns about security of supply and energy cost. This research examines the impact of high dependence of imported fuels for power generation in Spain through the quantification and analysis of the driving forces behind the change in its electricity bill. Following logarithmic mean Divisia indexes approach, we present and perform a new method that enables a complete decomposition of changes in electricity vulnerability into contributions from several drivers. In fact, we identify five predefined factors behind the variations in vulnerability in Spain during the 1998–2011 period: fuel price, average heat rate, fuel dependence, degree of electricity importance and energy intensity. The application of this approach reveals a significant increase in Spanish vulnerability in the last two decades, promoted by increments in fuel price and importance of electricity over the primary energy consumption, but especially by increasing fuel dependence (particularly gas dependence). Therefore, findings mainly advocate for those strategies aimed at reducing Spanish energy dependence. Also those improving thermal efficiency and energy intensity are indicated
Atitoaie, Alexandru; Stoleriu, Laurentiu; Tanasa, Radu; Stancu, Alexandru; Enachescu, Cristian
2016-04-01
The scientific community is manifesting a high research interest on spin crossover compounds and their recently synthesized nanoparticles, due to their various appealing properties, such as the bistability between a diamagnetic low spin state and a paramagnetic high spin state (HS), inter-switchable by temperature or pressure changes, light irradiation or magnetic field. The utility of these compounds showing hysteresis covers a broad area of applications, from the development of more efficient designs of temperature and pressure sensors to automotive and aeronautic industries and even a new type of molecular actuators. We are proposing in this work a study regarding the kinetic effects and the distribution of reversible and irreversible components on the thermal hysteresis of spin crossover nanoparticulated systems. We are considering here tridimensional systems with different sizes and also systems of nanoparticles with a Gaussian size distribution. The correlations between the kinetics of the thermal hysteresis, the distributions of sizes and intermolecular interactions and the transition temperature distributions were established by using the FORC (First Order Reversal Curves) method using a Monte Carlo technique within an Ising-like system.
Method of mechanical holding of cantilever chip for tip-scan high-speed atomic force microscope
International Nuclear Information System (INIS)
In tip-scan atomic force microscopy (AFM) that scans a cantilever chip in the three dimensions, the chip body is held on the Z-scanner with a holder. However, this holding is not easy for high-speed (HS) AFM because the holder that should have a small mass has to be able to clamp the cantilever chip firmly without deteriorating the Z-scanner’s fast performance, and because repeated exchange of cantilever chips should not damage the Z-scanner. This is one of the reasons that tip-scan HS-AFM has not been established, despite its advantages over sample stage-scan HS-AFM. Here, we present a novel method of cantilever chip holding which meets all conditions required for tip-scan HS-AFM. The superior performance of this novel chip holding mechanism is demonstrated by imaging of the α3β3 subcomplex of F1-ATPase in dynamic action at ∼7 frames/s
Yan, Yifei; Zhang, Lisong; Yan, Xiangzhen
2016-01-01
In this paper, a single-slope tunnel pipeline was analysed considering the effects of vertical earth pressure, horizontal soil pressure, inner pressure, thermal expansion force and pipeline-soil friction. The concept of stagnation point for the pipeline was proposed. Considering the deformation compatibility condition of the pipeline elbow, the push force of anchor blocks of a single-slope tunnel pipeline was derived based on an energy method. Then, the theoretical formula for this force is thus generated. Using the analytical equation, the push force of the anchor block of an X80 large-diameter pipeline from the West-East Gas Transmission Project was determined. Meanwhile, to verify the results of the analytical method, and the finite element method, four categories of finite element codes were introduced to calculate the push force, including CAESARII, ANSYS, AutoPIPE and ALGOR. The results show that the analytical results agree well with the numerical results, and the maximum relative error is only 4.1%. Therefore, the results obtained with the analytical method can satisfy engineering requirements. PMID:26963097
Liang, Zhang; Yanqing, Hou; Jie, Wu
2016-06-01
The multi-antenna synchronized receiver (using a common clock) is widely applied in GNSS-based attitude determination (AD) or terrain deformations monitoring, and many other applications, since the high-accuracy single-differenced carrier phase can be used to improve the positioning or AD accuracy. Thus, the line bias (LB) parameter (fractional bias isolating) should be calibrated in the single-differenced phase equations. In the past decades, all researchers estimated the LB as a constant parameter in advance and compensated it in real time. However, the constant LB assumption is inappropriate in practical applications because of the physical length and permittivity changes of the cables, caused by the environmental temperature variation and the instability of receiver-self inner circuit transmitting delay. Considering the LB drift (or colored LB) in practical circumstances, this paper initiates a real-time estimator using auto regressive moving average-based (ARMA) prediction/whitening filter model or Moving average-based (MA) constant calibration model. In the ARMA-based filter model, four cases namely AR(1), ARMA(1, 1), AR(2) and ARMA(2, 1) are applied for the LB prediction. The real-time relative positioning model using the ARMA-based predicting LB is derived and it is theoretically proved that the positioning accuracy is better than the traditional double difference carrier phase (DDCP) model. The drifting LB is defined with a phase temperature changing rate integral function, which is a random walk process if the phase temperature changing rate is white noise, and is validated by the analysis of the AR model coefficient. The auto covariance function shows that the LB is indeed varying in time and estimating it as a constant is not safe, which is also demonstrated by the analysis on LB variation of each visible satellite during a zero and short baseline BDS/GPS experiment. Compared to the DDCP approach, in the zero-baseline experiment, the LB constant
Systematic approach to establishing criticality biases
International Nuclear Information System (INIS)
A systematic approach has been developed to determine benchmark biases and apply those biases to code results to meet the requirements of DOE Order 5480.24 regarding documenting criticality safety margins. Previously, validation of the code against experimental benchmarks to prove reasonable agreement was sufficient. However, DOE Order 5480.24 requires contractors to adhere to the requirements of ANSI/ANS-8.1 and establish subcritical margins. A method was developed to incorporate biases and uncertainties from benchmark calculations into a keff value with quantifiable uncertainty. The method produces a 95% confidence level in both the keff value of the scenario modeled and the distribution of the keffS calculated by the Monte Carlo code. Application of the method to a group of benchmarks modeled using the KENO-Va code and the SCALE 27 group cross sections is also presented
Researching Sex Bias in the Classroom.
Donlan, Dan
This paper outlines five methods of research on sex bias in the classroom: one-time survey, one class/one treatment, two class/two treatment, one class/random assignment to treatment, and analysis of differentiated effect. It shows how each method could be used in attempting to measure the effect of a unit on Norma Klein's "Mom, the Wolfman and…