Quantifying technological aspects of process sustainability: a thermodynamic approach

Thermodynamic analysis has greatly helped to compare and to improve the energy efficiency of all kinds of technological processes, and recently we have also attempted to analyse some important biochemical processes under intracellular conditions. This work has pointed to some key strategies on sustainable process operation, such as the exceptionally high thermodynamic efficiencies of chemical and solar energy conversion in living cells.From this it was expected that the sustainability strategies of specific biochemical processes and those of the ecosphere as a whole could be of guidance to current technological processes, especially now that there is a growing demand from government and industry to effectively deal with sustainability aspects in process analysis. Our focus on this issue has led to methodologies to quantify technological aspects of sustainability by making use of thermodynamic principles. Three indicators were constructed to express three technological aspects of process sustainability. First, an indicator for the sustainability of resource utilization considers the thermodynamic input and the availability the resources used in the process. Secondly, an efficiency indicator focuses on the conversion and loss of thermodynamic quantities in the process itself. Thirdly, an indicator for environmental compatibility takes into account the thermodynamic input required to prevent possible negative side effects of the process, such as global warming or water pollution. The three indicators are used to reflect on (un)sustainable characteristics of current technological processes compared to biochemical processes. Finally, we address the drawbacks of combining indicator values to express overall sustainability.     

Analysis of Fourier synthesis holography for imaging through scattering materials

The technique of Fourier synthesis holography to image through scattering materials is analyzed in detail. A broad spectral source is decomposed into its Fourier components, and a hologram is formed at each wavelength and stored in the computer. Upon synthesis in the computer, a clear image can be formed of the obscured object. Post-data-acquisition processing such as selection of the gating time delay and autocorrelation shaping are also demonstrated.     

Hyperbaric reservoir fluids: High-pressure phase behavior of asymmetric methane +n-alkane systems

In this paper, experimental three-phase equilibrium (solidn-alkane + liquid + vapor) data for binary methane +n-alkane systems are presented. For the binary system methane + tetracosane, the three-phase curve was determined based on two phase equilibrium measurements in a composition range fromx _c24 = 0.0027 tox _c24 = 1.0. The second critical endpoint of this system was found atp = (1114.7 ± 0.5) M Pa.T = (322.6 ± 0.25) K, and a mole fraction of tetracosane in the critical fluidphase ofx _c24 = 0.0415 ± 0.0015. The second critical endpoint occurs where solid tetracosane is in equilibrium with a critical fluid phase (S _c24 +L =V). For the binary systems of methane with then-alkanes tetradecane, triacontane, tetracontane, and pentacontane, only the coordinates of the second critical endpoints were measured. The second critical endpoint temperature is found close to the atmospheric melting point temperature of then-alkane. The pressures at the second critical endpoints do not exceed 200 MPa. Based on these experimental data and data from the literature, correlations for the pressure. temperature, and fluid phase composition at the second critical endpoint of binary methane +n-alkane systems withn-alkanes between octane and pentacontane were developed.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Creep and rupture of an ods alloy with high stress rupture ductility

The creep and stress rupture properties of an oxide (Y₂O₃) dispersion strengthened nickel-base alloy, which also is strengthened by γ′ precipitates, was studied at 760 °C and 1093 °C. At both temperatures the alloy YDNiCrAl exhibits unusually high stress rupture ductility as measured by both elongation and reduction in area. Failure was transgranular, and different modes of failure were observed including crystallographic fracture at intermediate temperatures and tearing or necking almost to a chisel point at higher temperatures. While the rupture ductility was high, the creep strength of the alloy was low relative to conventional γ′ strengthened superalloys in the intermediate temperature range and to ODS alloys in the higher temperature range. These findings are discussed with respect to the alloy composition; the strengthening oxide phases, which are inhomogeneously dispersed; the grain morphology, which is coarse and elongated and exhibits many included grains; and the second phase inclusion particles occurring at grain boundaries and in the matrix. The creep properties, in particular the high stress dependencies and high creep activation energies measured, are discussed with respect to the resisting stress model of creep in particle strengthened alloys. RICHARD M. ARONS, formerly a Graduate Student at Columbia University     

High-resolution optical chirped pulse gating

We describe a system for achieving high-resolution range gating using optically chirped pulses. The technique converts signals from the time domain into signals in the frequency domain through a nonlinear, sum-frequency generation process. The technique is based on similar methods used in microwave radar. We draw analogies between our method and conventional and time-lens imaging processes, and present experimental results demonstrating the method.     

Carmi Harari (1920-2003).

Obituary for psychologist Carmi Harari (1920-2003). Among other things the obituary notes that, Harari was a noted psychoanalyst, clinical and forensic psychologist, disability examiner, and prolific workshop leader worldwide on issues of peacemaking and political psychology. He was an active officer and member of many international psychology groups, including the Psychologists for Social Responsibility, the National Register of Health Service Providers in Psychology, the National Accreditation Association for Psychoanalysis, the Council of Representatives of the APA (1974-1994), and the Committee on International Relations in Psychology. He served as president of the International Association of Applied Psychology, president of the New York State Psychological Association, and president of the Rockland County Psychological Society. Harari was an APA fellow in eight divisions, including Clinical, Psychotherapy, and Independent Practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Creep and strain recovery in hot-pressed silicon nitride

It is observed that creep response in hot-pressed silicon is characterized by two parallel phenomena; one accounts for a persistent non-recoverable plastic deformation and the other for a transient viscoelastic recoverable deformation. The persistent creep component is time-dependent, and apparently follows parabolic time kinetics. It is further observed that creep is characterized by a power law stress exponent of about 4 and an activation energy of 848 kJ mol^–1. The viscoelastic recoverable component of strain is found to be independent of the total plastic strain in the material. The recovery rate at any given time is directly proportional to the preceding creep stress and therefore can be considered linear viscoelastic. The creep compliance of the viscoelastic transient is temperature-dependent with an activation energy of about 722 kJ mol^–1. It is further observed that the viscoelastic recovery is characterized by a spectrum of retardation times and can be modelled by a series of Kelvin analogue models. Finally, the viscoelastic recovery and the viscoelastic component of subsequent creep appear to be inversely related and apparently obey Boltzman superposition. A model is developed for the creep and recovery behaviour of hot-pressed silicon nitride consistent with all experimental observations and based in relative grain motion accommodated by the fluid grain-boundary glass liquid flow, cavitation and wedge opening.     

Repeated isolation stress in the neonatal rat: Relation to brain dopamine systems in the 10-day-old rat.

Isolation of the rat pup from the nest and dam for one hour per day from PN 2–9 is a useful paradigm for producing stress in the neonate. These previously isolated rats respond to an amphetamine challenge with alterations in activity at the juvenile stage or as adults. Furthermore, when dopamine release is measured in the nucleus accumbens, juveniles release 3 times more dopamine after amphetamine than do controls. This study describes changes in behavior and brain dopamine systems at PN 10. Experiment 1 determined an appropriate amphetamine dose that could be used for behavioral activation at PN 10. Experiment 2 produced significant evidence of enhanced behavioral activation after the isolation paradigm and indicated that brain regions innervated by the mesolimbic dopamine system, septum, and hypothalamus display increased dopamine turnover and that the nigrostriatal pathway is less active. Likewise, in Experiment 3, in vivo microdialysis of the nucleus accumbens indicated that previously isolated pups respond to an amphetamine challenge with a several-fold increase in dopamine release over a 4-hour session. (PsycINFO Database Record (c) 2010 APA, all rights reserved)