Effect Of Small Errors Research Articles

What gas exchange data can tell us about photosynthesis.

What gas exchange data can tell us about photosynthesis.

Analyses of Error and Precision of 6-DOF Platform

A particular subset of 6-DOF parallel mechanisms is known as Stewart platforms (or hexapod). Stewart platform characteristic analyzed in this paper is the effect of small errors within its elements (strut lengths, joint placement) which can be caused by manufacturing tolerances or setting up errors or other even unknown sources to end effector. The biggest kinematics problem is parallel robotics which is the forward kinematics. On the basis of forward kinematic of 6-DOF platform, the algorithm model was built by Newton iteration, several computer programs were written in the MATLAB and Visual C++ programming language. The model is effective and real-time approved by forwards kinematics, inverse kinematics iteration and practical experiment. Analyzing the resource of error, get some related spectra map, top plat position and posture error corresponding every error resource respectively. By researching and comparing the error spectra map, some general results is concluded.

The ACPI Climate Change Simulations

The Parallel Climate Model (PCM) has been used in the Accelerated ClimatePrediction Initiative (ACPI) Program to simulate the global climateresponse to projected CO2, sulfate, and other greenhouse gasforcingunder a business-as-usual emissions scenario during the 21st century. In these runs, the oceans were initialized to 1995 conditions by a group from the Scripps Institution of Oceanography and other institutions. An ensemble of three model runs was then carried out to the year 2099 using the projected forcing. Atmospheric data fromthese runs were saved at 6-hourly intervals (hourly for certain criticalfields) to support the ACPI objective of accurately modeling hydrologicalcycles over the western U.S. It is shown that the initialization to1995 conditions partly removes the un-forced oceanic temperature and salinity drifts that occurred in the standard 20th century integration. The ACPI runs show a global surface temperature increase of 3–8 °C over northern high-latitudes by the end of the 21st century, and 1–2 °C over the oceans. This is generally within ±0.1°Cof model runs without the 1995 ocean initialization. The exception is in theAntarctic circumpolar ocean where surface air temperature is cooler in theACPI run; however the ensemble scatter is large in this region. Althoughthe difference in climate at the end of the 21st century is minimalbetween the ACPI runs and traditionally spun up runs, it might be largerfor CGCMs with higher climate sensitivity or larger ocean drifts. Ourresults suggest that the effect of small errors in the oceans (such asthose associated with climate drifts) on CGCM-simulated climate changesfor the next 50–100 years may be negligible.

Determination of the combustion properties of natural gases by pseudo-constituents⋆

This paper presents a methodology for a rapid determination of important natural gas combustion properties (lower heating value, Wobbe index and the stoichiometric air–fuel ratio) using easily detectable physical properties. It is possible to determine natural gas composition by measuring two physical properties and using specific ternary diagrams (CH4–C2H6–C3H8 and CH4–C2H6–N2). The first part of the work deals with the selection of two physical properties from a group comprising thermal conductivity, refraction index, and speed of sound. Then, in the second part, a sensor using the best couple of physical property is used to determine the ternary pseudo-constituents of the gas mixture. The model and the sensor are applied to specific situations such as the online determination of LHV. The error on the combustion properties of natural gas is less than 1% over the gases considered in the present study and over about 20 typical gases supplied over Europe. The effect of small errors in the measurement of physical properties has also been highlighted.

Robustness of Nonlinear Filters Over the Infinite Time Interval

Nonlinear filtering is one of the classical areas of stochastic control. From the point of view of practical usefulness, it is important that the filter not be too sensitive to the assumptions made on the initial distribution, the transition function of the underlying signal process and the model for the observation. This is particularly acute if the filter is of interest over a very long or potentially infinite time interval. Then the effects of small errors in the model which is used to construct the filter might accumulate to make the output useless for large time. The problem of asymptotic sensitivity to the initial condition has been treated in several papers. We are concerned with this as well as with the sensitivity to the signal model, uniformly over the infinite time interval. It is conceivable that the effects of even small errors in the model will accumulate so that the filter will eventually be useless. The robustness is shown for three classes of problems. For the first two cases, the signal model is Markov and the observations are taken in discrete time, and the observation is the usual function of the signal plus noise. The last class treated is a continuous time Markov process, with a point process observation.

Magnetic Configuration Scans in H-1 Heliac

The results of the experimental study of the magnetic configurations in the H-1 heliac are presented. The shape of the flux surfaces and the rotational transform in H-1 can be controlled by varying external coil currents. Electron beam magnetic mapping has been performed to show the existence of closed nested flux surfaces and to observe the effect of small errors in coil alignment on the vacuum magnetic structure in H-1. Langmuir probes have been used to study the electron density profiles in a current-free collisional RF-sustained plasma (n{sub e}<=4 x 10{sup 12} cm{sup -3}, T{sub e}<= 15 eV). In standard magnetic configuration and for the present moderate RF power levels, the highest central density is achieved at rather low magnetic field (0.07 T). This regime is characterized by peaked density profiles that appear to have a maximum coincident with the position of the vacuum magnetic axis. When a lowest-order m=1, n=1 resonance is introduced inside the outermost magnetic surface a strong asymmetry in both the vacuum magnetic structure and the plasma density profiles is observed. We observed low frequency (2-3 kHz) density fluctuations having low radial mode numbers and internal parallel plasma current localized in the regions of highest densitymore » gradient. These fluctuations are effectively suppressed by an increase of the magnetic field. 4 refs., 6 figs.« less

Effects of Small Errors in Electrode Placement on Body Composition Assessment by Bioelectrical Impedance

Effects of Small Errors in Electrode Placement on Body Composition Assessment by Bioelectrical Impedance

Selective Area Chemical Vapor Deposition of Silicon by the Alternating Cyclic Method: A Thermodynamic Analysis

The selective area chemical vapor deposition of silicon using the alternating cyclic, A. C., hydrogen reduction of is discussed from the perspective of a thermodynamic analysis over a broad pressure and temperature range. The analyses incorporated the thermodynamic data for all the known species in the Si‐H‐Cl and Si‐H‐Cl‐Ar systems. The A. C. concept is based on the sequential hydrogen reduction of , followed cyclically by the etching of spurious nuclei of silicon via an embedded disproportionation reaction. The analysis indicates the feasibility of the A. C. technique and identifies the temperature and total system pressure range for maximum process efficiency. The effect of small errors in the thermodynamic data of the vapor phase species on the results of the calculations has also been investigated.

Division-of-wave-front thin-film beam splitter for generating binary patterns of orthogonal elliptical polarization states

A division-of-wave-front thin-film beam splitter is described that reflects monochromatic light at oblique incidence with orthogonal elliptical polarization states. It consists of a metallic substrate partially covered with a transparent thin film that inverts the ratio ρ of the complex p and s reflection coefficients at the principal angle of the metal. Any pattern of coated and uncoated areas of the substrate is imprinted upon the reflected wave front as a corresponding two-dimensional spatial binary polarization pattern. A specific design is given that uses a Au substrate at a wavelength of 632.8 nm. The effects of small errors in the film refractive index, the film thickness, and the angle of incidence are discussed. It is noted that a layer that inverts ρ at a certain (especially high) angle of incidence is an effective ρ-inverting layer at all angles.

Linearization of second‐order reaction data

AbstractReaction data described by the second‐order growth function A(t) = A∞(αt) (1 + αt)−1, where A∞ is the ultimate value of the product concentration A(t), can be linearized by plotting a suitable function F(t) against the time (t). The slope of the straight line obtained is (2α), where α is the product of the rate constant (k2) and the initial concentration of either reactant, with the result that k2 can be determined without knowledge of Aϰ. Optimal determination of the parameter α requires that data taking be limited to the interval 0 ≤ t ≤ T, where (αT) is approximately 4.0. Numerical data derived from an experiment on the exchange of lead by zinc ions in the enzyme carbonic anhydrase are analyzed to illustrate the method. The effects of small errors in the initial concentrations and of small deviations from second‐order kinetics are briefly discussed.

On the extended-range predictability of large-scale quasi-stationary patterns in the atmosphere

A principal objective of this article is to establish theoretically the result that, contrary to some previously held beliefs, internal nonlinear processes (wave-wave and wave-mean interactions) among the large scales not likely to be the dominant mechanisms that lead to unpredictability of the low-frequency portion of the large-scale waves in the extra-tropical atmosphere. It is further argued that theoretically quasi-stationary long waves can probably be predicted at extended ranges if boundary forcings and tropical influence can be treated as known during the range of prediction. The problem of long-range predictability of quasi-stationary long waves is studied here using a three-dimensional quasi-geostrophic channel model of the atmosphere, with lateral and lower boundary forcings prescribed. The low-frequency component of the flow is isolated by taking the running-time mean with an averaging period taken to be longer than the typical lifecycle of synoptic-scale baroclinic waves. When this period is chosen to be 10 days or longer, it is found that the evolution of the large-scale flow is not governed by a regular initial-value problem and detailed information of the initial condition is not “remembered‘ by the quasi-stationary waves beyond the predictability limit for the atmosphere as a whole. Instead, it is found that the extended-range evolution of the stationary waves responds to the corresponding evolution of the zonal index, which measures the total zonal geostrophic angular momentum in the channel. Some issues of theoretical predictability, such as the effect of small errors in the initial condition and of small uncertainties in our knowledge of the transient eddy fluxes, are addressed. It is argued that, since the evolution of the zonal index is found to be governed by a remarkably simple first order nonlinear differential equation of a single scalar function of time, whose solution has predictable properties, the quasi-stationary long waves, whose evolution is determined by the prognostic information contained in the zonal index, are perhaps also predictable beyond the “predictability limit”. DOI: 10.1111/j.1600-0870.1986.tb00419.x

Reduction of interaction tones from axial flow fans by suitable design of rotor configuration

An expression is derived to give details of the acoustic power radiated by a circular array of point dipoles situated in free air. The phase relationships existing between the sources are contrived to be of the type generated by the interaction of axial flow fan aerofoil rows, and thus a simple model for the acoustic output of a fan due to the fluctuating forces on the stator vanes is obtained. The effects of small errors in source (vane) location are investigated, and hence a realistic estimate of the behaviour of such phased arrays derived. It is shown that the large reduction in discrete tone radiation anticipated through a suitable choice of blade and vane numbers is critically dependent on exact cascade geometry, and hence additional methods must be used if tonal annoyance is to be eliminated. The removal of discrete tones from fan noise by the uneven circumferential distribution of the rotor blades is then re-examined in the light of this work, and some suggestions made as to how this technique might be most conveniently and effectively employed. The work is illustrated by theoretical and experimental results for a small axial flow fan.

The effects of error in the element values and the converter transfer characteristic on the responses of active rc filters

This paper first deals briefly with negative impedance converters and with the methods of active network synthesis devised by Linvill and Yanagisawa. The greater part of the paper treats the effects of small errors in the element values and in the transfer characteristic of the negative impedance converter on the response of low-pass Maximally Flat Magnitude (Butterworth) and Equal Ripple (Chebyshev) filters of secondorder. Butterworth and Chebyshev filters of the fourth-order are also considered. Curves are given showing the way in which the errors distort the response characteristics; the importance is pointed out of the proximity to the negative impedance converter of a circuit element having an error in its value. A symmetry between the effects of error in circuit elements on either side of the converter is also noted. The method of display of the sensitivity of circuits to errors used in this paper is believed to be unique for active networks in that the effect on the response curve is shown directly. In other work on the subject, reviewed in this paper, equations are given showing the sensitivity of the poles of the network function to changes in element values and converter sensitivity. The pole shifts are, of course, a measure of the effect on the response of the filter but the effect is shown more clearly when a change in the response curve is given.

On the Effects of Small Errors in the Angles of Corner-Cube Reflectors

When a ray is reflected successively on three mirrors that are approximately mutually perpendicular, the ray is returned nearly parallel to the original direction. If the original and final directions are denoted by unit vectors q and −t, and if a, b, c are the normals to the three mirrors taken in order in a right-handed sense, then it is shown theoretically that t=q+2q×(+αa-βb+γc),to the first order in α, β, γ, where these are the small angles by which the angles between the three mirrors exceed right angles. A geometrical construction to realize this formula is described.If the three reflecting faces are parts of the surface of a symmetrical solid tetrahedron, refraction at the fourth surface increases the angular deviation of the final ray from the incident ray by a factor of μ cosr/cosi for the component of the deviation in the plane defined by the incident ray and the normal, and by a factor of μ for the perpendicular component. (i is the angle of incidence, and μ sinr=sini.)Finally, it is shown theoretically that this type of reflecting unit (with a curved refracting surface), when used at the rear of road vehicles, could have greater efficiency if one of the angles between the reflecting surfaces were 90.14 deg instead of 90 deg.