Acoustic device for aiming at a tree a mechanism for holding a machine for stacking trees with root systems

The results of laboratory and industrial tests of an acoustic device for aiming at a tree are presented. The device may be used in machines in the agricultural and timber industry. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 45–47, August, 1998.     

Similarity law for radiant-heat-transfer coefficient for a body in a hypersonic flow

The flow of radiating gas around a blunt body with intense vaporization is analyzed. Calculations are made for air and a hydrogen-helium mixture. Universal relations between the radiant-heat-transfer coefficients and the scintillation parameter are derived.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol, 36, No. 2, pp. 244–248, February, 1979.     

Cryogenic dual-mode resonator for a fly-wheel oscillator for a caesium frequency standard

A dual-mode, sapphire-loaded cavity (SLC) resonator has been designed and optimized with the aid of finite element software. The resonance frequency was designed to be near the frequency of a Cs atomic frequency standard. Experimental tests are shown to agree very well with calculations. The difference frequency of two differently polarized modes is shown to be a highly sensitive temperature sensor in the 50 to 80 K temperature range. We show that an oscillator based on this resonator has the potential to operate with fractional frequency instability below 10/sup -14/ for measurement times of 1 to 100 seconds. This is sufficient to operate an atomic clock at the quantum projection noise limit.     

A reference model for a flowmeter magnetic field for a computing experiment

A reference model is considered for a magnetic field intended for checking programs and algorithms defining the electromagnetic field in an electromagnetic flowmeter measurement channel. __________ Translated from Izmeritel’naya Tekhnika, No. 4, pp. 39–41, April, 2007.     

On a proposal for a continuum with microstructure

Summary A recently proposed model for a continuum with microstructure is further substantiated by identifying the microstructure with dislocations. In particular, the continuum is viewed as a superimposed state composed of a perfect lattice state, an immobile dislocation state, and a mobile dislocation state. It is assumed that each state evolves continuously in space-time and transitions from one state to another take place spontaneously according to the balance laws of effective mass and momentum. When the constitutive equations are subjected to the requirements of invariance, familiar statements from dislocation dynamics are deduced. When plastic strain and yield are identified in terms of the parameters characterizing the dislocation states, familiar flow rules and yield surfaces are produced. The capability of the model to predict not only Tresca and Von-Mises plastic behavior but also phenomena such as kinematic hardening, different responses in tension and compression, latent hardening, and the Bauschinger effect, is shown. Finally, the appropriateness of our equations to model creep, cyclic plasticity, and fatigue, is illustrated.With 2 Figures     

Models for a Multichannel Meter for Parabolic Characteristics

Block diagrams are considered for two-channel and three-channel meters for determining the parameter of a parabolic characteristic for an electronic component or device. The accuracy in measuring the exponent is examined. Possible applications of the meters are indicated.     

Sensitivity analysis of a comprehensive model for a miniature-scale linear compressor for electronics cooling

A comprehensive model of a linear compressor for electronics cooling was previously presented by Bradshaw et al. (2011). The current study expands upon this work by first developing methods for predicting the resonant frequency of a linear compressor and for controlling its piston stroke. Key parameters governing compressor performance – leakage gap, eccentricity, and piston geometry – are explored using a sensitivity analysis. It is demonstrated that for optimum performance, the leakage gap and frictional parameters should be minimized. In addition, the ratio of piston stroke to diameter should not exceed a value of one to minimize friction and leakage losses, but should be large enough to preclude the need for an oversized motor. An improved linear compressor design is proposed for an electronics cooling application, with a predicted cooling capacity of 200 W a cylindrical compressor package size of diameter 50.3 mm and length 102 mm.     

Exploring a Bayesian hierarchical approach for developing safety performance functions for a mountainous freeway

While rural freeways generally have lower crash rates, interactions between driver behavior, traffic and geometric characteristics, and adverse weather conditions may increase the crash risk along some freeway sections. This paper examines the safety effects of roadway geometrics on crash occurrence along a freeway section that features mountainous terrain and adverse weather. Starting from preliminary exploration using Poisson models, Bayesian hierarchical models with spatial and random effects were developed to efficiently model the crash frequencies on road segments on the 20-mile freeway section of study. Crash data for 6 years (2000–2005), roadway geometry, traffic characteristics and weather information in addition to the effect of steep slopes and adverse weather of snow and dry seasons, were used in the investigation. Estimation of the model coefficients indicates that roadway geometry is significantly associated with crash risk; segments with steep downgrades were found to drastically increase the crash risk. Moreover, this crash risk could be significantly increased during snow season compared to dry season as a confounding effect between grades and pavement condition. Moreover, sites with higher degree of curvature, wider medians and an increase of the number of lanes appear to be associated with lower crash rate. Finally, a Bayesian ranking technique was implemented to rank the hazard levels of the roadway segments; the results confirmed that segments with steep downgrades are more crash prone along the study section.     

Proposal for a new scheme for producing a two-photon,high dimensional hyperentangled state

We propose an experimentally feasible scheme for generating a two 2?×?4?×?4 dimensional photon hyperentangled state, entangled in polarization, frequency and spatial mode. This scheme is mainly based on a parametric down-conversion source and cross-Kerr nonlinearities, which avoids the complicated uncertain post-selection. Our method can be easily expanded to the production of hyperentangled states with more photons in multidimensions. Hence the expectation for vast quantities of information in quantum information processing will possibly come true. Finally, we put forward a realizable quantum key distribution (QKD) protocol based on the high dimensional hyperentangled state.     

$200,000 for a photograph

Abstract

A defining moment in the history of photography in Chicago occurred in the summer of 1946. For six weeks, from 8 July to 16 August, world-renowned photographers convened for lectures, seminars, field trips, and demonstrations to inaugurate the new department of photography and its four-year programme at László Moholy-Nagy's Institute of Design (ID).1 Moholy founded the New Bauhaus in Chicago in 1937; it closed after little more than a year. It reopened in 1939 as the School of Design, and in 1944 the name was changed once more to the Institute of Design. The ID still exists in Chicago today but since 1949 has been a school within the Illinois Institute of Technology. Paul Strand, Berenice Abbott, Beaumont Newhall, Roy Stryker, and Erwin Blumenfeld all taught at the seminar, as did Arthur Siegel, Frank Scherschel, Gordon Coster, and Moholy himself The ‘New Vision in Photography’ seminar established the tenor of all subsequent teaching at the ID. Henceforth, learning photography there would be collaborative, practical, professional, intellectual, and have strong components of film and photohistory. Since many of the most important American photographers of the 1950s, 1960s, and 1970s were students at the ID (among them Thomas Barrow, Linda Connor, Barbara Crane, Kenneth Josephson, Ray K. Metzker, Richard Nickel, Arthur Sinsabaugh and Charles Swedlund) it is fur to say that the seminar directly impacted on the course of photography in the postwar period. And because it produced so many college-level instructors, the ID is regarded as ‘the seminal institution for the development of college-level photography programs’.²