Amplitude Variability in Simulated Incoherent Seismic Ground Motions

This note compares in detail four commonly used schemes for the simulation of spatially variable ground motions. Emphasis is placed not only on the conformity of the simulations with the power and cross spectral density of the random field but, also, on the examination of the consistency of the simulations with the homogeneity condition, and the (Fourier) amplitude variability of the simulations. It is shown that, whereas three techniques that simulate ground motions in parallel satisfy the homogeneity requirement, produce simulations with random amplitudes, and amplitude and phase variability consistent with that of recorded data, one technique that simulates motions in sequence does not.     

Enumeration of bifidobacteria in dairy products

There is much interest in the potential role of bifidobacteria as dietary inclusions, but their isolation from dairy products, and subsequent identification, can cause problems. A range of selective and non-selective media were examined, and modified Rogosa agar was found to give the best recovery from yogurt-like products. A morphological examination of typical isolates suggested that only bifidobacteria had grown on the medium, but confirmation by means of biochemical tests proved inconclusive, and it seems that the genus/species definition merits further attention.     

Seismic loads predicted by spatial variability models

Seismic loads that result from different expressions describing the spatial variability of the seismic ground motions at the supports of lifelines are evaluated and compared in this study. The analysis considers two spatial variability models, that are commonly used in lifeline earthquake engineering, namely the ones developed by Harichandran and Vanmarcke (J. Eng. Mech., 112 (1986)) and by Luco and Wong (Earthquake Eng. Struct. Dyn., 14 (1986)). It is shown that the models produce significantly different seismic loads for the analysis of buried and above-ground lifelines.     

Seismic source mechanisms and ground motion models

A summary of the recently developed analytical models for the prediction of strong ground motions is presented in this paper. The models are classified into two groups: The first describes root mean square, peak values and Fourier spectra of ground accelerations and velocities, whereas the second develops power spectral densities, cross correlation coefficients and spatial variations of ground motions. Several source models used in the inverse problem, namely the problem of inferring source mechanisms from recorded data, are also discussed.     

Electromagnetic Heating for Industrial Kilning of Malt: a Feasibility Study

Industrial malting operations use ～800 kWh/t of energy to produce the heat required to kiln malt. Electromagnetic heating technologies are suggested as a way to potentially improve the energy efficiency of the kilning processing. In this work, the potential for using electromagnetic heating to dry malt to commercially acceptable moisture levels whilst preserving the activity of enzymes critical for downstream brewing processes is investigated. The 2450 MHz bulk dielectric properties of malt at moisture contents consistent with those occurring at different points in the kilning process are evaluated; 12% is shown to be a critical moisture level below which drying becomes more energy intensive. Calculated penetration depths of electromagnetic energy in malt at radio frequency are 100-fold higher than at microwave frequencies, showing a significant advantage for commercial-scale batch processing. The moisture contents and alpha and beta amylase activity of malt subjected to RF heating at different temperatures, treatment times and RF energy inputs in the intermediate and bound water drying regions were determined. It is shown for the first time that whilst significantly reduced process times are attainable, significant energy efficiency improvements compared to conventional kilning can only be achieved at higher product temperatures and thus at the expense of enzyme survival. It is suggested that RF heating may be feasible where higher bulk temperatures are not critical for downstream use of the material or when used in hybrid systems.     

Challenges in the Processing Line of Spanish Style cv. Chalkidiki Green Table Olives Spontaneously Fermented in Reduced NaCl Content Brines

In this work, the effect of different treatments using selected combinations of chloride salts (NaCl, KCl, CaCl_2, MgCl₂) in fermentation brine to assess the safety, quality, and nutritional value of the Spanish style cv. Chalkidiki green table olives spontaneously fermented is studied. Examination of safety parameters (bacteria/yeasts, pH, acidity) and changes in olive color and texture characteristics in brines during fermentation, and in mineral content of olives upon storage up to 12 months, is conducted using appropriate methods. Sensory evaluation takes place in certain cases. Among the tested salt combinations, those of 4.08% NaCl, 2.8% KCl, 1% CaCl₂, and 0.12% MgCl₂ (w/v) are found to be the most effective regarding safety, color, texture, and taste. Findings support that Spanish style cv. Chalkidiki green olives can be spontaneously fermented in reduced NaCl content brine. The 50% lower NaCl content of the fermented olives compared with that in traditionally fermented ones suggests that reformulation of cv. Chalkidiki green table olives by safe intervention is feasible. Practical Applications: cv. Chalkidiki green table olives are of high importance for the Greek economy. Traditionally they are spontaneously fermented in NaCl brine (8% w/v). Partial replacement of NaCl content with other salts in such a line results in a product acceptable in terms of safety and quality characteristics. The Greek table olive industry may profit from the findings in an attempt to remodel the traditional spontaneous fermentation in green olive processing according to international dietary guidelines.     

Assessing quantities and disposal routes for household hazardous products in the United Kingdom

The disposal of household products containing hazardous substances (household hazardous wastes; HHW) is of concern due to possible health and environmental effects as a consequence of environmental pollution. The potential risks of disposal are proportional to the amounts of products used and waste generated, but much of the data relating to quantities are old, inconsistent, or nonexistent. Hence, full-scale risk assessment is not yet feasible. This pilot study was aimed at an initial assessment of the amounts of hazardous products used or stored within the household and potential disposal routes. Representatives of 400 households from southeast England were interviewed about socio-demographic factors, perception of the risks associated with the use and disposal of hazardous waste generated in households, quantities of particular products currently in use or stored within the household, and times and methods of disposal of such products. The estimates of quantities obtained were compared with sales figures and waste estimates to improve understanding of product flow through to the HHW stream. The disposal routes investigated demonstrated that most householders claim to use the entire product priorto disposal in the general refuse bin. The relationship with socio-demographic factors demonstrated a difference between neighborhood size and length of residence in a household with regard to product quantities possessed and the disposal habits adopted.     

Effect of spatial variability and propagation of seismic ground motions on the response of multiply supported structures

The response of lifelines, modelled as two- and three-span continuous symmetric beams of various lengths, subjected to partially and fully correlated seismic ground motions is examined. The partial correlation of the input motions consists of a term that characterizes the loss of coherence and a term that represents the apparent propagation (phase difference). The analysis suggests that the propagation effects may be neglected when the motions at the site exhibit loss of coherence; however, when the motions are coherent, phase differences may produce higher or lower response than the one induced by fully correlated motions, depending on whether the dominant modes are antisymmetric or symmetric at the location along the beam and for the response quantity (bending moment or shear force) under consideration.     

Development of differential response spectra for lifeline seismic analysis

An important consideration in the seismic analysis and design of long lifelines is the differential ground motion at their supports, which may induce significant stresses and strains in the structure. Presented herein are empirical, closed from expressions of differential ground motions. These expressions are approximations of the analytical results obtained by Zerva et al.¹ and depend on a few parameters that vary with separation distance.

The empirical approximations, and the results of the analytical model are used as input motions in the evaluation of the dynamic response of a specific lifeline system. Axial and transverse (horizontal and vertical) motions are considered. The results of the analysis indicate that simplified expressions, such as the empirical approximations presented herein, may adequately describe the effect of differential ground motions on lifelines. Finally, the differential response spectrum, namely the variation of the maximum differential displacement in a pipeline with the natural frequency of the system, is introduced.