Prevalence of teen driver errors leading to serious motor vehicle crashes

Objectives

Motor vehicle crashes are the leading cause of adolescent deaths. Programs and policies should target the most common and modifiable reasons for crashes. We estimated the frequency of critical reasons for crashes involving teen drivers, and examined in more depth specific teen driver errors.

Methods

The National Highway Traffic Safety Administration's (NHTSA) National Motor Vehicle Crash Causation Survey collected data at the scene of a nationally representative sample of 5470 serious crashes between 7/05 and 12/07. NHTSA researchers assigned a single driver, vehicle, or environmental factor as the critical reason for the event immediately leading to each crash. We analyzed crashes involving 15–18 year old drivers.

Results

822 teen drivers were involved in 795 serious crashes, representing 335,667 teens in 325,291 crashes. Driver error was by far the most common reason for crashes (95.6%), as opposed to vehicle or environmental factors. Among crashes with a driver error, a teen made the error 79.3% of the time (75.8% of all teen-involved crashes). Recognition errors (e.g., inadequate surveillance, distraction) accounted for 46.3% of all teen errors, followed by decision errors (e.g., following too closely, too fast for conditions) (40.1%) and performance errors (e.g., loss of control) (8.0%). Inadequate surveillance, driving too fast for conditions, and distracted driving together accounted for almost half of all crashes. Aggressive driving behavior, drowsy driving, and physical impairments were less commonly cited as critical reasons. Males and females had similar proportions of broadly classified errors, although females were specifically more likely to make inadequate surveillance errors.

Conclusions

Our findings support prioritization of interventions targeting driver distraction and surveillance and hazard awareness training.     

Effect of block copolymer dopants and alkylsilane monolayers on the fracture toughness of polystyrene-glass interfaces

The asymmetric double cantilever beam fracture test has been used to study the fracture toughness of polystyrene (PS)-glass interfaces reinforced with poly(deuterostyrene-b-2 vinyl pyridine) (dPS-PVP) as a function of degree of polymerization of the blocks. The effect of modifying the glass substrate with various selfassembled monolayers is also described. For the block copolymer with degrees of polymerization,N _dPS=656 andN _PVP=46 (referred to asN _dPS —N _PVP or 656-46), located at the interface between glass and PS, the interface fails by chain scission at areal chain densities, , of the block copolymer below a critical value, ^*. Above this value, e.g. > ^*, the interface fails by crazing followed by chain scission. For the 656-46 diblock copolymer, the transition is located at ^*=0.03 chains nm^–2, which results in a calculated force to break a C-C bond along the polymer backbone of approximately 2 × 10^–9N. For the 800–870 diblock copolymer at the interface between glass and PS, failure occurs due to chain scission. Fracture of both the 656-46 and the 800–870 block copolymers at the interface between (OTS) octadecyltrichlorosilane monolayer coated glass and PS is due to chain pulloff of the block copolymer from the OTS coated glass. Very little additional stress was transferred across the interface, resulting in fracture toughnesses comparable to that of a PS-glass interface with no block copolymer added.     

Statistical filtering of useful concrete creep data from imperfect laboratory tests

The reporting and evaluation of creep tests of concrete is complicated by the fact that creep is significant even for the shortest observable load durations. Compared to the strain after 0.1 s load duration, the strain at 2 h duration is typically 53% greater. Most experimenters have for decades been unaware of this fact. Consequently, the reported creep curves require correction by a time shift, which ranges from 0 to 2 h. This further implies a vertical shift of entire creep curve, important for all times up to structure lifetime. To filter out the errors, it is argued that, within an initial period during which the advance of hydration is negligible, which is normally about 1 day, the initial basic creep must follow a power law of the time. Creep test data from the literature are used to prove it. Corrections by time and deformation shifts are determined by minimization of the sum of squared deviations of the power law from the creep test data. For a fixed exponent n and time shift s, the optimization is reduced to linear regressions of two kinds, depending on whether the data are given in terms of either the compliance function or the creep coefficient. For both, the linear regression parameters depend nonlinearly on the chosen values of n and s. To avoid nonlinear optimization, which need not converge to the correct result, a set of many discrete values of n and s within their realistic ranges is selected and the (n, s) combination minimizing the objective function is obtained by a search. Enforcing a power law form of the initial creep curve is found to lead to better data fits. The optimum exponent n for the entire database is around 0.3, applicable to the time period cca (10 s, 1 day). After that, the exponent transits to about 0.1, and prior to that it is about 0.08. After filtering out the errors, the corrected database will allow better calibration of the general creep prediction model such as B3 or B4.     

Describing function‐based approximations of biomolecular systems

Mathematical methods provide useful framework for the analysis and design of complex systems. In newer contexts such as biology, however, there is a need to both adapt existing methods as well as to develop new ones. Using a combination of analytical and computational approaches, the authors adapt and develop the method of describing functions to represent the input–output responses of biomolecular signalling systems. They approximate representative systems exhibiting various saturating and hysteretic dynamics in a way that is better than the standard linearisation. Furthermore, they develop analytical upper bounds for the computational error estimates. Finally, they use these error estimates to augment the limit cycle analysis with a simple and quick way to bound the predicted oscillation amplitude. These results provide system approximations that can add more insight into the local behaviour of these systems than standard linearisation, compute responses to other periodic inputs and to analyse limit cycles.Inspec keywords: molecular biophysics, physiological models, approximation theoryOther keywords: describing‐function‐based approximations, mathematical methods, computational approaches, biomolecular signalling systems, hysteretic dynamics, saturating dynamics, analytical upper bounds, computational error estimates, oscillation amplitude     

Microstructural analysis of Au/Pt/Ti contacts to p-type InGaAs

A detailed study on the microstructural changes that occur on annealing of Au/Pt/Ti ohmic contacts to n-type InGaAs has been carried out. The metal layers were deposited sequentially by electron beam evaporation onto InGaAs, doped with Zn to a level of 7 × 10¹⁸ cm^–3, that was epitaxially grown on < 100 > InP substrates. The deposition sequence and metal layer thicknesses were: Ti (25 or 30 nm), Pt (25 or 30 nm) and Au (250 or 300 nm). Samples were annealed at temperatures ranging from 250–425 C in a nitrogen atmosphere. As-deposited contacts were Schottky barriers, while a minimum contact resistance of 2 × 10^–5 cm² was obtained by annealing in the 375–425 C range. Annealing resulted in the inward diffusion of Ti and outward diffusion of In and As, leading to the formation of TiAs, metallic In and Ga-rich InGaAs at the Ti/InGaAs interface. The Pt diffusion barrier was effective in preventing In diffusion into the outer Au layer and minimizing Au diffusion to the semiconductor.     

Multiplying circuits with semiconductor diodes

Conclusions The characteristics of semiconductor diodes type D9E and other types have a steeper slope than the approximated parabola. It is, therefore, possible by connecting a building-out resistor in series with the diode to make up a two-terminal network whose characteristic has three common points with approximated parabola. The error of approximation then does not exceed 2%.In order to preserve the square-law characteristic of the two-terminal resistance-diode network despite changing temperature it is necessary to connect a thermistor in series with the diode. Thermistors type MMT are suitable for use with diodes type D9E.Temperature changes produce variations in the characteristics of diodes and thermistors which form part of the circuit, thus leading to errors. The compensation of these errors can be attained by means of thermistors types MMT and KMT.Tests have shown that the referred error of thermally-compensated diode multiplying circuits does not exceed 2–3% in the temperature range of 20±10 C.     

The 0–2 Transition of CO in Condensed Oxygen,Nitrogen, and Argon

Infrared absorption spectra of CO in the region of the first overtone have been observed in dilute (approximately 1 to 10 parts in 1000) liquid solutions of oxygen, nitrogen, and argon, and clear crystalline nitrogen and argon matrices. The overtone band was found at 4249.0, 4252.4, and 4252.0 cm⁻¹ with half widths of 18.4, 17.8, and 13.7 cm⁻¹ in liquid oxygen, nitrogen, and argon solutions at 82, 78, and 82 °K, respectively. The half width in liquid oxygen varied from 18.4 to 10.0 cm⁻¹ in the temperature range 82 to 57 °K. The band position was the same but its width was smaller in the crystalline nitrogen matrix. Two bands were observed in the clear crystalline argon solid at 4245 and 4256 cm⁻¹. The solution results cannot be interpreted with the recent theory of Buckingham.Infrared absorption spectra of carbon monoxide in the region of the first overtone have been observed in the liquid solvents oxygen, nitrogen, and argon. In addition, the spectra have been obtained in clear crystalline solutions of argon and of nitrogen near the triple points of these solvents. The purpose of these experiments was to determine the influence of temperature, phase changes, and solvents on half width, position, and shape of the CO absorption band.A Perkin-Elmer model 99 monochromator with a 2000 lines/cm grating blazed at 10° (1.7μ in first order) was used in the first order with a spectral slit width of about 1 cm⁻¹. An antireflection coated germanium filter eliminated the higher orders from the 1000 w tungsten filament lamp used as the light source. The quartz absorption cell used, recently described by Bass and Broida [1], was modified slightly by recessing the windows further into the coolant tube. The resultant increased thermal contact between the refrigerant and the solution greatly simplified the growing of the clear crystalline matrices. The temperature of the refrigerant, liquid oxygen, was regulated by pumping on it with a small vacuum pump (capacity 14 liters/min). The vapor pressure of the liquid oxygen refrigerant, measured with an aneroid type gauge, provided an indication of the temperature. The direct measurement of the vapor pressure above the solution with a mercury manometer also provided an indication of the temperature. Solutions were prepared from the gases which had been mixed in the ratios of 1 to 10 parts carbon monoxide to 1000 parts of the various solvents. The position, the half width, and the shape of the spectral band did not depend on the concentration in this range. The clear solid solutions were grown slowly from the liquids at or near the triple points of the solvents.The measured frequencies and half widths of the 0–2 transition of CO in condensed oxygen, nitrogen, and argon are summarized in 2]). There were no changes in the position or the shape of the band in liquid oxygen at temperatures from 57 to 82 °K. However the half-band width varied from 10.0 to 18.4 cm⁻¹ in this temperature range. In liquid argon the band is slightly asymmetric with more absorption on the high-frequency side.

Table 1

The 0–2 transition of CO in condensed oxygen, nitrogen and argon

Determining the error in reproducing continuous random signals by means of pulsed frequency transducers

Conclusions Owing to the application of the suggested parameters , , _ge, and m which characterize the PFM system, it is possible to approximate the error relationships by means of linear functions convenient for calculations. The suggested technique can be applied for determining modulation and restoration errors of voltage-to-frequency and frequency-to-code transducers for various signal distribution laws and correlation functions.Translated from Izmeritel'naya Tekhnika, Vol. 19, No. 6, pp. 25–26, June, 1976.     

Quantitative estimation of measurement errors for general technological parameters

Results are presented on the metrological characteristics of multichannel data-acquisition systems (DAS) that perform indirect measurements. General and typical structures are given for such DAS, which are represented by mathematical models for the errors in processing the data in them. An analysis is presented of the dependence of the error on the DAS parameters and input signals.Translated from Izmeritelnaya Tekhnika, No. 10, pp. 16–20, October, 2004.     

Measurement of angle errors of mutual inductance coils by means of an alternating current bridge

Summary In using the described method for the measurement of angle errors of mutual inductance coils, it should be kept in mind that the error is determined by a number of factors, of which eddy currents in windings and the distributed capacitance are the most important. The presence of distributed capacitance leads to a situation where, in transition from the accordant connection of windings to connection in opposition, the leakage current changes. Therefore, the measured value of the angle error can be, generally speaking, substantially different from the value obtained if the given coil is used as an actual measure of the 90° phase shift. Consequently, the described method of measuring the angle error is suitable for those mutual inductance coils where the capacitance leakage is sufficiently small or does not change to a great extent when the coil connections are interchanged.It should be remarked that this circumstance affects the measured value of the coefficient of mutual inductance to a certain extent if the measurement results are obtained by using (6).Finally, we shall make another remark regarding the difference (R₂-R₁). In deriving (7), it was assumed that the resistance of both coils remained unchanged during the measurements. As the resistance corresponding to the loss angle is small, in order that the above condition be satisfied, it is necessary, in particular, to keep the temperature conditions of the coils under careful control by not overloading them with a current which would cause appreciable heating.The requirement for the stability of resistances can be set forth in a concrete manner by assigning a certain given error caused by their instability.Denoting the change in resistance by R, we obtain accordingly:Thus, for R=1000 cps, M=0.01 h, and for =5·10^–5, we have R=3·10^–3 ohm.     

Exploiting intrinsic fluctuations to identify model parameters

Parameterisation of kinetic models plays a central role in computational systems biology. Besides the lack of experimental data of high enough quality, some of the biggest challenges here are identification issues. Model parameters can be structurally non‐identifiable because of functional relationships. Noise in measured data is usually considered to be a nuisance for parameter estimation. However, it turns out that intrinsic fluctuations in particle numbers can make parameters identifiable that were previously non‐identifiable. The authors present a method to identify model parameters that are structurally non‐identifiable in a deterministic framework. The method takes time course recordings of biochemical systems in steady state or transient state as input. Often a functional relationship between parameters presents itself by a one‐dimensional manifold in parameter space containing parameter sets of optimal goodness. Although the system''s behaviour cannot be distinguished on this manifold in a deterministic framework it might be distinguishable in a stochastic modelling framework. Their method exploits this by using an objective function that includes a measure for fluctuations in particle numbers. They show on three example models, immigration‐death, gene expression and Epo‐EpoReceptor interaction, that this resolves the non‐identifiability even in the case of measurement noise with known amplitude. The method is applied to partially observed recordings of biochemical systems with measurement noise. It is simple to implement and it is usually very fast to compute. This optimisation can be realised in a classical or Bayesian fashion.Inspec keywords: biochemistry, physiological models, stochastic processes, measurement errors, fluctuations, parameter estimationOther keywords: model parameter identification, deterministic framework, biochemical system, steady state, transient state, stochastic modelling framework, objective function, immigration‐death model, gene expression, Epo–EpoReceptor interaction, stochastic fluctuations, measurement noise     

Note on the Thermal Degradation of Polytetrafluoroethylene as a First-Order Reaction

Additional experiments on the rates of thermal degradation of polytetrafluoroethylene in a vacuum confirm an earlier conclusion that a first-order rate law is involved in the degradation reaction.In a study made by Madorsky, Hart, Straus, and Sedlak¹ on the rates and activation energy of thermal degradation of polytetrafluoroethylene in a vacuum, two methods were employed: a gravimetric method, using a very sensitive tungsten spring balance in a vacuum system to measure the rate of loss of weight of the degrading sample, and a pressure method, using a multiplying manometer to measure the pressure of the C₂F₄ formed in the reaction. The material that was used was in the form of a tape 0.07 mm thick. Weight of the sample was about 7 mg in the gravimetric experiments and 5 to 306 mg in the pressure experiments.The rates obtained by the gravimetric method are reproduced in figure 1, plotted as a function of percentage loss of weight of the sample for 480, 490, 500, and 510 °C. The initial rates were obtained by extrapolating the rate curves to the ordinate. The rate curves beyond the initial 5 to 18 percent loss of weight of the sample are straight lines, and when extended to the right they approach near the zero rate at 100 percent volatilization. The rates obtained by the pressure method were studied at 10 different temperatures ranging from 423.5 to 513.0 °C. Logarithms of the initial rates obtained by both methods are shown in figure 2 plotted against the inverse of absolute temperature.² From the Arrhenius equation the slope of the resulting straight line indicates an activation energy of 80.5 kcal/mole. From the appearance of the curves in figure 1 it seemed logical to conclude that the reaction involved in the thermal degradation of polytetrafluoroethylene in a vacuum follows a first-order law.Open in a separate windowFigure 1Rate of thermal degradation of polytetrafluoroethylene by the weight method as a function of percentage volatilization.Open in a separate windowFigure 2Activation energy slope for thermal degradation of polytetrafluoroethylene.●—weight method (see footnote ¹)○—pressure method (see footnote ¹)■—present work.At a later date Wall and Michaelson³ studied the rate of thermal degradation of polytetrafluoroethylene at 460 °C in a stream of nitrogen. They used a gravimetric method by heating 1-g samples of a powdered material and weighing the residues at intervals. They state that below about 480 °C the reaction is zero order, whereas above 510 °C they concede it is first order.In view of this result by Wall and Michaelson, it was deemed advisable to check further on the rate order involved in the thermal degradation of this material in a vacuum. Although experiments by the pressure method were carried out in our earlier work at temperatures below 480 °C, the extent of volatilization was at most only 6.4 percent. Degradation had not been carried far enough to determine accurately whether the percentage loss versus time plots were straight or curved lines, i.e., whether the indicated reaction is of zero or first order. Rate experiments were therefore carried out by the weight method at lower temperatures, namely at 460, 475, and 485 °C, and the results are shown in figure 3, where percentage loss of weight is plotted against time. The curves are definitely not straight lines, as would have been the case if the reaction had followed a zero order.Open in a separate windowFigure 3Pyrolysis of polytetrafluoroethylene at low temperatures.In our previous work (see footnote ¹) the rates were obtained by plotting the slopes between two neighboring experimental points in the volatilization-time plots. In the present work the slopes were calculated from the curves shown in figure 3, and the resulting rate curves based on these calculations are shown in figure 4. The same type of rate curves were obtained as in the earlier work. Values obtained for the initial rates at these three temperatures fit nicely into the Arrhenius plot, as shown by the squares in figure 2.Open in a separate windowFigure 4Rates of thermal degradation of polytetraduoroethylene at low temperatures.The present work therefore confirms our earlier conclusion that the degradation of polytetrafluoroethylene in a vacuum follows a first-order rate law, where the rate of volatilization, based on the sample, is directly proportional to the amount of residue.     

Absolute Configuration and Chemical Topology

The stereochemistry of catenanes, knotted molecules, and Borromean rings is discussed. An augmentation of the Cahn-Ingold-Prelog convention for designating absolute configuration is proposed. A convention is proposed for designating the absolute configuration of knotted molecules. A suggestion is made concerning the citing of the absolute configuration of molecularly dissymmetric diastereomers.Proposals of rules for designating absolute configuration have been put forth by Cahn, Ingold, and Prelog¹ and by Terentiev and Potapov.² The rules of the latter workers are deliberately linked to nomenclature. Those of the former workers rely entirely on structure and have found wide acceptance among organic chemists. In their closely reasoned paper Cahn, Ingold, and Prelog properly claim to have covered by their rules all known types of dissymmetry deriving from tetracovalent and tricovalent atoms.Work aiming toward the establishment of a major system for handling chemical information requires the ability precisely to designate chemical structures without recourse to structural formulas. A number of notation systems have been devised for representing chemical structures by linear arrays of symbols,³ although none of the systems has yet been perfected even for organic compounds.⁴ Since an adequate information handling system must accommodate not only all known structural types but also those structural types which have to date been merely speculated on, an examination of more esoteric stereochemistry was undertaken. I now wish to propose an augmentation of the Cahn-Ingold-Prelog (C-I-P) rules and the addition of a new (specialized) set of rules to cover a wider range of molecularly dissymmetric structural types.The molecularly dissymmetric structures for which further rules are necessary are of two types: (1) substituted catenanes,⁵ which are stereochemically related to substituted allenes and spiro compounds, and (2) knots,⁶, ⁷ compounds whose dissymmetry is due entirely to topology, independent of substitution. ^{6, 7} The C-I-P convention is inapplicable to knots and before being applied to catenanes requires a further convention for defining the “near groups”.     

Note on Particle Velocity in Collisions Between Liquid Drops and Solids

Equations are developed for plane-wave particle velocity produced in solid-against-liquid collisions. An explicit expression for the dimensionless coefficient α that appears in these equations is deduced.Collisions between liquid drops and the planar surfaces of solids have become important in the present era of high-speed flight. Except for the pressure that results when a drop of incompressible liquid collides with the planar surface of an unyielding solid [1],¹ exact hydrodynamic treatments of the various aspects of this type of collision have not been developed. Plane-wave theory has been used in several approximate treatments [2, 3, 4]. One of the unknowns encountered in the use of plane-wave theory for solid-against-liquid collisions was the particle velocity in the compressed zones.During collision between a solid rod A having flat ends and moving with velocity V in the (+z)-direction of a stationary coordinate system (fig. 1) and a similar liquid rod B that is at rest, there is a radial flow of liquid at the impacted end of rod B. In order that the rods remain in contact while the compressional waves initiated by the collision move through them, the interface velocity (I) must obey the inequality V−v′ >v where v′, v are the particle velocities in the compressed zones.Open in a separate windowFigure 1Collision between a plate moving at velocity V and a liquid drop at rest idealized as collision between a solid rod A and a liquid rod B.We can then write α(V−v′)=v where α is a dimensionless coefficient having a value less than one, and v + αv^′ = αV.(1)Using the relation that exists between stress and particle velocity for plane waves, the equality of stresses at the surfaces of contact is given by zv = z^′v^′, (2)where z is the acoustic impedance (product of sound speed and density). From eq (1) and (2), the particle velocities v, v′ are found to be v = αz^′V/(z^′ + αz)(3) v^′ = αzV/(z^′ + αz), (4)and the plane-wave stress σ is given by σ = σ^′ = αzz^′V/(z^′ + αz).(5)The quantity that must be determined to make these equations useful is the coefficient α.One of the approximate treatments in which plane-wave theory was used for solid-against-liquid collisions [3] provides a means of deducing an explicit expression for the coefficient α. In this treatment the complicated situation of collision between a moving target plate and a relatively stationary liquid drop was idealized as the simple case of the collision of two rods with flat ends. If a plate is fired against a drop (fig. 1), a core of material extending through the plate under the contact area is slowed down with respect to the remainder of the plate and a similar core of material through the drop is set in motion. The cores were regarded as true cylinders free to move in the z-directions (fig. 1) but restrained laterally. The compressional waves that move through the cylinders were regarded as plane waves.With use of this simple model, an equation was developed that gives pit depth δ′ as a function of impingement velocity V for collisions of metal target plates with liquid drops [3]. For impingement velocities for which elastic recovery of the plate is complete, the pit depth was taken to be the product of a numerical constant, the particle velocity given to the cylindrical core of material under the collision area, and the time that the particle velocity exists. The particle velocity was taken to be zV/(z+z′), which is the plane-wave particle velocity for solid-against-solid collisions. The time during which the particle velocity exists was taken to be 2d/c where d is the diameter of the drop and c is the sound speed of the liquid of which it is composed. Therefore, δ′ = (constant) (d/c) [zV/(z+z′)].The pit-depth equation that was developed was applied first to collisions of mercury drops and waterdrops with target plates of copper, 1100–O aluminum, 2024–O aluminum, steel, and lead. The constant was found empirically to be 7.2. The equation was then found to apply without change of the constant to collisions between metal target plates and soft ductile metal spheres that flowed during and as a result of the collision.The same equation was later applied [4] to collision of steel spheres against target plates of 1100–O aluminum, 2024–O aluminum, and copper. It was found empirically that if the target plate was struck by a rigid hardened steel sphere that did not flow as a result of the collision the constant was 17.5.The constants found for the pit-depth equation for the case that a target plate collides with a liquid drop or soft ductile metal sphere and for the case that it collides with a rigid hardened steel sphere provide a means of obtaining an explicit expression for the coefficient α. The two cases differ only in the particle velocity given to the core of material through the target plate. The particle velocity v′ for solid-against-solid collisions was used in each case. The particle velocity v′ for solid-against-liquid collisions should have been used for the case that the target plate collided with a liquid drop or with a soft deforming metal sphere that would flow as a result of the collision.Because it is the particle velocity given to the core of target material under the collision area that is different, and because the constant 7.2 is 0.41 of the constant 17.5, it follows that αzV/(z′+αz) = 0.41 zV/(z′+z) from which α = 0.41/[1 + (0.59 z/z^′)].(6)Values of α calculated with use of eq (6) for collisions of waterdrops and mercury drops with target plates of aluminum, copper, lead, and glass are given in 2]. It was found experimentally [2] that 0.00118 sec were required for a glass plate to move through a 0.57-cm-diam waterdrop when the relative impingement velocity was 820 cm/sec (26.9 ft/sec). The velocity at which the plate moved through the drop was 484 cm/sec. It was assumed that no particle velocity was given to the cylinder of glass through the plate under the collision area. Then the velocity at which the plate moved through the drop was (1−α)V. To this degree of approximation (1−α)820 = 484 and α = 0.4.Table 1Some values of the coefficient α

Solid hydrogen and deuterium. II. Pressure and compressibility calculated by a lowest-order constrained-variation method

The pressure and the compressibility of solid H₂ and D₂ are obtained from ground-state energies calculated by means of a modified variational lowest-order constrained-variation (LOCV) method. Both fcc and hcp structures are considered, but results are given for the fcc structure only. The pressure and the compressibility are calculated or estimated from the dependence of the ground-state energy on density or molar volume, generally in a density region of 0.65^–3 to 1.3^–3, corresponding to a molar volume of 12–24 cm³/mole, where = 2.958 å, and the calculations are done for five different two-body potentials. Theoretical results for the pressure are 340–460 atm for solid H₂ at a particle density of 0.82^–3 or a molar volume of 19 cm³/mole, and 370–490 atm for solid ⁴He at a particle density of 0.92^–3 or a molar volume of 17 cm³/mole. The corresponding experimental results are 650 and 700 atm, respectively. Theoretical results for the compressibility are 210 × 10^–6 to 260 × 10^–6 atm^–1 for solid H₂ at a particle density of 0.82^–3 or a molar volume of 19 cm³/mole, and 150 × 10^–6 to 180 × 10^–6 atm^–1 for solid D₂ at a particle density of 0.92^–3 or a molar volume of 17 cm³/mole. The corresponding experimental results are 180 × 10^–6 and 140 × 10^–6 atm^–1, respectively. The agreement with experimental results is better for higher densities.     

Analog-digital converter having apparatus monitoring

Conclusions

1. Since the converter carries out, during its operation, the checking of each recorded stage during the course of a conversion, it is possible to replace, during the conversion process, the stage having a systematic error by means of a spare stage, i.e. to increase its reliability substantially.
2. The detection and elimination of systematic errors of converter stages permits a transition to the probabilistic principle of increasing accuracy by increasing the number of converter stages in exchange for a reduction in speed [4].
3. It is possible to generate the conversion result with a code indicating the confidence interval of the error.

     

Experimental investigation of subjective errors in decoding circular diagrams

Conclusions The subjective error in decoding a circular diagram is a substantial component of the total circular-diagram measurement error. It was found that in measuring roundness irregularities below 1 , which corresponds to shape precision I, II, and III of GOST (All-Union State Standard) 10356-63, the subjective decoding error may attain 50% of the measured quantity.This error in measuring roundness irregularities which approach 1 can be substantially reduced by providing additional expansion steps.The subjective decoding error consists of the error in finding the center and diameter of the basic circumference and of the error in estimating the position of the most distant point from the basic circumference. These are random errors. Numerical characteristics of their statistical distribution have been established for reading errors at ¯S_o=±0.06 templet divisions, for finding the position of the center at ¯S_c=±0.2 templet divisions, and for determining the diameter of the basic circumference at S_d=+-0.09 templet divisions.It has been established that the decoding of circular diagrams entails the operator in the complicated visual problem of orientation by means of templet scale lines and of tracing one of these lines. His task can be greatly facilitated by altering the design of the templet.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 27–31, May, 1968.