Kinds Of Curves Research Articles

The polode synthesis method

The Polode Synthesis method makes use of inversion letting the end point of the coupler of a dyad move on the desired curve keeping the other end joint fixed. The resultant moving centrode and moving polodes yield information about where solutions can be found. The method can be applied towards path generation, timed path generation, function generation, motion generation and timed motion generation. If neither the corresponding centrode nor the polodes intersect then, in general, the resultant coupler curve has only 4 points common with the desired curve. If the polodes intersect then 6-point solutions are obtained etc. The method is applied to straight line mechanisms where the coupler curve is to deviate little from the straight line over the entire range. The same kind of curve is generated so that certain crank positions correspond to certain positions of the coupler point. The method is then applied to a circular arc. The generation of an approximate ellipse is shown for illustrative purposes and the resultant curve is almost identical to the ellipse. The new method approximates the entire curve rather than selecting a few precision points through which the resultant coupler curve is intended to pass. However, only part of the desired curve may be prescribed. The method can be applied to any combination of links and joints.

Ultrasonography and gastric emptying: evaluation in infants with gastroesophageal reflux.

We have applied ultrasonography to the evaluation of gastric emptying in children. Two different populations have been investigated: normal children and children with gastroesophageal reflux. All the patients were less than 6 months of age. The diagnosis of gastroesophageal reflux was defined by 24-h pH measurement. The technique, used to measure gastric emptying, is the one described by Bolondi et al. In this research we used the simplified method. All children had been submitted to the examination after 4-h fasting. The standard meal was the usual milk formula, 300 ml/m2 body surface area (BSA). A cross-section area of the gastric antrum was determined before a meal and every 15 min for 2 h. The examination was concluded after two measurements were equal to the basal one. The normal gastric emptying curve was determined by a control group. Patients with gastroesophageal reflux showed three different kind of gastric emptying: (a) normal gastric emptying in 20% of cases, (b) abnormal gastric emptying in 15% of cases, and (c) intermediate cases in which the plateau curve is abnormal but the end time of gastric emptying is normal. We defined these three kinds of curves as type I or normal, type III or abnormal, and type II or intermediate. The estimate of frequency in patients with gastroesophageal reflux is similar to the reported data of the literature.

Ultrasonography and Gastric Emptying

We have applied ultrasonography to the evaluation of gastric emptying in children. Two different populations have been investigated: normal children and children with gastroesophageal reflux. All the patients were <6 months of age. The diagnosis of gastroesophageal reflux was defined by 24‐h pH measurement. The technique, used to measure gastric emplying, is the one described by Bolondi et al. In this research we used the simplified method. All children had been submitted to the examination after 4‐h fasting. The standard meal was the usual milk formula, 300 ml/m2 body surface area (BSA). A cross‐section area of the gastric antrum was determined before a meal and every 15 min for 2 h. The examination was concluded after two measurements were equal to the basal one. The normal gastric emptying curve was determined by a control group. Patients with gastro‐esophageal reflux showed three different kind of gastric emptying: (a) normal gastric emptying in 20% of cases, (b) abnormal gastric emptying in 15% of cases, and (c) intermediate cases in which the plateau curve is abnormal but the end time of gastric emptying is normal. We defined these three kinds of curves as type I or normal, type III or abnormal, and type II or intermediate. The estimate of frequency in patients with gastroesophageal reflux is similar to the reported data of the literature.

Gas transmission properties of polyvinyl chloride (PVC) films studied under subambient and ambient conditions for modified atmosphere packaging applications

AbstractThis study was undertaken to determine the gas transmission properties of three polyvinyl chloride (PVC) films mostly used as overwrap for fresh produce under subambient and ambient conditions (5–40°C). Three different kinds of curves or groups of data are presented: gas transmission rates, activation energy measurements and the permeability coefficient. Hydrophobic by nature, the PVCs are not affected in their gas transmission properties (O2, CO2) by the moisture level. Reliable gas transmission data were obtained with method variability (≤9%) over a wide range of temperature. Regression constants, activation energies for prediction equations and permeability ratios (CO2/O2) are presented for the three films. Greater uniformity in test procedures, and the presentation of permeability data normalized to 1 μm instead of 1 mil would simplify comparative studies within and between countries, laboratory services and from the scientific literature. More research is needed to study the wide variety of polymers available under subambient conditions.

Flow in Spillways with Gradually Varied Curvature

In the conventional design of a spillway invert and flow bucket, circular, elliptic, and parabolic curves are generally used to connect straight boundaries. Because of the abrupt change in curvature at tangency points, considerable drop of pressure may occur, which sometimes causes cavitation damage. Two kinds of curves with gradually varied curvature, CGVC 1 and CGVC 2, are suggested in spillway design to connect two given points. The slope and the curvature at both ends are specified for a CGVC 1 curve. For a CGVC 2 curve, with other conditions the same as CGVC 1, the curvature at the downstream end is not prescribed. A variable domain finite element scheme, in which the location of the free surfaces of the jet is determined simultaneously with the stream function, is then briefly described. The proposed curves with gradually varied curvature are used in four sample designs. Computational results with the finite element scheme indicate that the new designs give better pressure distribution than the conv...

Tunneling measurements of the energy gap in the high-Tc superconductor Tl2Ba2Ca2Cu3O10+ delta.

The tunneling I-V characteristic curves have been studied for a ceramic sample of ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{10+\mathrm{\ensuremath{\delta}}}$ using a scanning tunneling microscope. We have found two kinds of curves which are interpreted as due to the tunneling in superconductor--insulator--normal-metal and superconductor-insulator-superconductor junctions. Although the ${T}_{c}$ of the intervenient superconducting regions are unknown, values of 2\ensuremath{\Delta}/${k}_{B}$${T}_{c}$ are around the BCS value 3.5 using the ${T}_{c}$ obtained by resistance measurements.

Thermoanalytical examination under quasi-isothermal—quasi-isobaric conditions

The review begins with a short introductive survey on the history of the development of quasi-static measuring techniques. Thereafter, the authors give a detailed description of the measuring principles and theoretical fundamentals of the methods developed by themselves, of the so-called quasi-isothermal—quasi-isobaric (Q-TG and Q-TD) technique as well as of the simultaneous Q-TG/Q-DTG/Q-DTA and Q-TG/Q-TGT methods. Using examples, they demonstrate the characteristic types of the new kinds of curves and classify them according to their interpretation. With the presentation of a rather large amount of experimental material, the aim of the authors, beyond demonstrating the advantages of the methods, is also to express their disbelief in the justification of calculations of reaction kinetic parameters on the basis of dynamic thermoanalytical curves.

A method for detecting correspondences in a sequence of modifying shapes

It is interesting in many fields to analyze motion patterns generated by time-varying shape boundaries. When dealing with such a problem a possible initial approach consists of establishing a correspondence between segments obtained by decomposing boundary lines belonging to successive frames. In this work a mathematical model of moving shape boundaries is constructed. A technique for accomplishing related decompositions of such kinds of curves residing in contiguous frames is presented. Finally an algorithm based on the relaxation and tree search methods generates a correspondence process between tokens belonging to successive frames. Examples and results are displayed and discussed.

A unified molecular force field via a model theory of isoelectronic diatomic molecules

Electronic energy curves for diatomic molecules come in a wide variety of shapes. More categorically, these correspond to stable, metastable or repulsive states. We propose that a great deal of this apparently diverse behavior might in fact be contained in a single isoelectronic energy surface E(R,Z,Z′). That is, each kind of curve can be thought of as a particular cross section of the surface corresponding to some range of the nuclear charges Z and Z′. Analytic representations for these surfaces have been given and their properties examined. We have found that they are folded and contain critical points. These features put limits on the number of isoelectronic species that can exist in a sequence and interconnect their properties. By this we understand that data gathered on even the repulsive states of one molecule of an isoelectronic sequence contains information about the stable and metastable members of that sequence.

Colloid characterization by sedimentation field-flow fractionation. III. Emulsions

The successful application of sedimentation field-flow fractionation (sedimentation FFF) to the characterization of monodisperse and polydisperse particle populations was extended to the determination of the droplet size distribution (DSD) of emulsions. The theory and advantages of sedimentation FFF are briefly reviewed, and it is shown quite generally that the centrifugal field is not sufficiently strong to cause droplet distortion, aggregation, or other similar disturbances. Two different sets of experiments, applied to two commercial emulsions used for intravenous nutrition, are described. The safflower oil emulsion, subjected primarily to self-consistency tests, was shown to yield virtually identical raw DSD curves despite changes in field strength, sample size, flow velocity, and instrumental systems. For the soybean oil emulsion, a detector response correction factor was obtained by dissolution of the emulsion. It was shown that changes in the manufactured emulsion product could be followed by directly observing changes in the fractogram, or by noting changes in the DSD curves. The conditions under which the different kinds of curves can be used for comparative purposes were outlined.

Polymerization/excision kinetics of Escherichia coli DNA polymerase I. Stability in kinetic behaviour and variations of the rate constants with temperature and pH.

1. The incorporation and excision kinetics of Escherichia coli DNA polymerase I in the replication of (dA)n with dUTP and (dI)n with dCTP was studied at various temperatures and pH. When the incorporation/excision ratio (dy/dx) is plotted against the concentration of deoxynucleoside triphosphate [S] two kinds of curves are obtained. With (dI)n, dy/dx increases with [S], then reaches an asymptotic value. This behaviour, consistent with a kinetic amplification or kinetic proofreading mechanism, is observed at all temperatures and pH. With (dA)n, dy/dx increases with [S] but in a convex, instead of a concave manner. In this case, we approximated the curves by straight lines at the origin, in conformity with the prediction of the frayed-unfrayed model. Again a single behaviour is consistently observed at all temperatures and pH. 2. The data were analyzed in terms of ratios or products of three kinetic constants: ki for incorporation, ke for excision and, in the (dI)n system, theta for the processing of the incoming dNTP. The dNMP production in the (dI)n system is dominated by the ke theta term which increases with temperature and pH. Temperature influences excision more than incorporation, the net result being a linear decrease of ki/ke with temperature. The effect is more pronounced with (dI)n than with (dA)n and is probably related to the stability of the template-primer complex. The ki/ke term shows a bell-shaped dependency with pH in the (dI)n system. With (dA)n it remains constant between pH 7.5 and 8.5 then decreases with a transition midpoint at pH 9.0. We suggest that the pH profiles may reflect the ionization of the template in the first case, and of the substrate in the second.

Etude, par atd, du diagramme d'etat de l'arsenic et mesure de son enthalpie de fusion aux conditions du point triple

For DTA studies, arsenic samples are placed in silica ampoules which are evacuated and sealed. Since the arsenic sample does not fill the whole inner volume of the ampoule, theV/m ratio (whereV is the inner volume andm is the weight of the sample) can be varied. Depending on theV/m value, two kinds of curves are obtained. The distribution of phase regions in theT vs.V/m space is described. This distribution makes it possible to determine the specific volume of arsenic vapor at the triple point. The result obtained (7.90 mm3 mg−1) is consistent with As4 molecules in the vapor phase. From the DTA curves obtained, the heat of fusion of arsenic is estimated. The result (24.2 kJ mol−1) is consistent with the values reported in the literature.

A New Method of Nonlinear Analysis for Threshold and Shaping Actions in Transient States

Threshold and shaping actions of a dynamical system are analyzed in the phase plane. Attention is focussed on two kinds of curves (A-type and R-type curves) of the trajectory. The A-type curve causes the stabilization of the process, such as the shaping action; while the R-type curve causes the growth of the difference between two states of the system, such as the threshold action. As curves corresponding to the A-type (or R-type) curves, an A-inflector (or R-inflector) is defined. Their properties are investigated. The A-type (R-type) curve is located in the neighborhood of the A-inflector (R-inflector). The BVP model of an excitable membrane is taken as an example. This model is analyzed by the use of the A-inflector and the R-inflector. An algebraical equation for the threshold value and a necessary condition for the occurrence of threshold action are discussed.

Snap Loads in Taut Moored Platforms

It is shown by both model tests and theoretical analyses that the dynamic response of taut moored platforms subjected to regular waves can be divided by two kinds of curves into three categories, harmonic response, non-linear response with snap loads and other non-linear response.A new theory to analyze the snap load is proposed. This theory consists of time combinations of solutions of the linear differential equations corresponding to several kinds of wire states. The characteristics of the non-linear response with snap loads are clarified qualitatively and also quantitatively by the theoretical calculations and the model tests.

Population growth regulated by intraspecific competition for energy or time: Some simple representations

An examination is made of some of the ways populations can grow in response to changes in their own density. Under two different assumptions on birth and death rates, models for single-species population growth that incorporate intraspecific competition by interference but not exploitation are of logistic form. Where an individual's net energy input from feeding is inversely proportional to population size, population growth follows a convex curve, whether interference is included or not. Data of Smith (1963) on Daphnia populations are fit well by this kind of curve. Combination of the two kinds of growth can produce S-shaped curves whose inflection is displaced from that value—half the carrying capacity—given by the logistic; an upward displacement is favored by a high ratio of metabolic and replacement costs to feeding input. Inflection points from real curves are much more often higher than expected from the logistic. Nonmonotonic growth curves can arise when there is instantaneous feedback between consumers and resource availability; certain of these equations are of logistic or convex form at equilibrium. The possible effect of r- and K-selection on the biological parameters, such as feeding efficiency, used to construct the monotonie equations is discussed, and the equations are extended to 2-species competition. Table III characterizes some simple single-species growth curves.

Synthesis of dispersed surface waves by means of Fourier transform

ABSTRACT Flexual disturbances propagated upon a thin aluminum plate were studied experimentally. The thickness of the plate is 1.0 mm., and the distances between the source and the observation points are r = 0, 3.0, 5.0, 7.0, 15.0, and 20.0 cm. Using the method of Fourier transform, the dispersion curve was obtained. It agrees well with the theory, and the thickness of the plate was estimated with good accuracy (0.981 mm.). Disturbances at the distances 7.0, 3.0, and 0 cm. were numerically reproduced by means of Fourier synthesis from the data obtained at r = 15 cm. and 20 cm., and were compared with the observed disturbances. The agreement of the two kinds of curves are fairly good, with a little larger discrepancy for the case r = 0 than for the others.

Absolute amplitudes and spectra of certain musical instruments and orchestras

Measurements made on instruments and orchestras, during the playing of selections, include average amplitudes in long intervals (15 seconds) and distribution of peaks in very short intervals (one-eighth second). Octave and half-octave bands are measured, as well as unfiltered music. The instruments tested were selected as possibly contributing extreme frequencies and amplitudes. Calculations of peak acoustic powers range as high as 27 watts. Although different techniques would be applied today, such as the use of a recorded tape to insure exact duplication of a selection as different frequency bands are explored, and the measurement of rms rather than average amplitudes, it is nevertheless felt that the measurements were reasonably accurate. The type of presentation, however, left something to be desired. Both kinds of curves will be found here in new forms. For the peaks, the plan used later in presenting similar data on speech has been adopted. The average amplitudes are reduced to a per-cycle basis in a different manner. Both types are plotted in absolute rather than relative units, and are reduced to a common distance. The table of peak powers is recalculated, using the same assumptions as before, but making the estimate for the 1 per cent level of intervals, in all cases. All new reductions and calculations are made from the original measured data. Some changes in the text are necessary to describe the revisions of the figures, and a few comments have been added. The term "bar" which was in current use in 1931 for "dyne per square centimeter," is changed here to "microbar." The "Historical Note," which appeared at the end of the original paper, has been shortened somewhat and made a part of the introduction.

Examples of geoelectric surveys

The Introduction deals briefly with the general principles underlying geoelectric methods of surveying and gives a simple formula for the apparent resistivity at a given depth below the surface in a homogeneous medium. The two problems of interpreting the different kinds of curves obtained from field measurements and of determining the depth of the associated geological anomalies are discussed.In Section 1.2 the electrical equipment and field procedure are briefly described.Three particular anomalies are considered in Section 1.3. These are:(i) Parallel strata as illustrated by the boulder-clays which overlie the chalk of the Holderness Plain, East Yorkshire.(ii) Inclined strata which occur where the water-table reaches the surface on the slopes of the Mendip Hills, Somerset.(iii) A cavern in the limestone rocks at Pen Park near Filton, Bristol.In Sections 2, 3 and 4 respectively, the relevant equations, the geoelectric measurements and graphs together with their interpretations are discussed. The equation for inclined strata is deduced in a form comparable with the previously published equations for parallel strata and a spherical cavity. These latter are stated in Sections 2 and 4 respectively, and their derivation is given in the Appendix.From the graphs in Section 2 it is concluded that no ancient Humber estuary existed in the chalk beneath the boulder-clays, but the presence of an interglacial gravel separating two deposits of boulder-clays is established.In Section 3 the water-table is located and is found to emerge along a line of springs which coincides with the edge of the conglomerate deposited by the ancient Triassic sea.The deductions made from the graphs of Section 4 were verified by subsequent excavations which led to the rediscovery of Pen Park Hole.In the Appendix the derivation of the equations for a homogeneous medium, for parallel strata and for a buried sphere are given, together with theoretical relationships for calculating the depths of these particular anomalies.

A differential thermal analysis of soil humus

Abstract Many papers have been reported of soil minerals by means of the thermal differential analysis because of its great advantage. There have been. however, a quite few papers reported of soil humus, even though the humus is a constituent of soil that plays a very important role particularly in the field of soil fertility in itself and in combining with soil minerals. One of the difficulties of the study of humus appears to be due to the complexity of its structure. The report made in this paper will be the first step in the study of the structure of humus. In other words, the object of this paper is to check what kind of curve will be obtained by the thermal analysis method when soil humus is used.

Study of Clinical Application of Electrocardiographic Local Leads, especially of Local Leads Standardized by Maekawa (I)

(I)Practical and analytical methode of Local Leads. The Local Leads Electrocardiograms in this study are obtained by Chest and Esophageal Leads and they are composed of two kinds of curves which have R and F as indifferent electrodes in the same lead point. This paper showed that it is possible to know the unipolarity of Local Lead Electrocardiograms by comparative observation on the resemblance of these two kinds of curves, and rneasurement of Stimulus Arrival Time by means of Maekawa's method can give accurate analysis of conduction disturbance not only in ventricle but also in auricle.