Purpose – The purpose of this paper is to present a hierarchy decision model for assessing the priority of safety management elements in manufacturing enterprises with reference to three major industries (i.e. textile and clothing, electronics, and printing and publishing) in Hong Kong. The identification of core decision criteria and safety management elements were addressed with respect to the effective implementation of safety management systems (SMS) in manufacturing enterprises.Design/methodology/approach – Empirical data were acquired via a conduct of personal interviews with evaluators (i.e. safety personnel, experts and professionals) in industry. Using the analytic hierarchy process (AHP) methodology, a list of seven decision criteria and 13 safety management elements were identified and their relative importance were evaluated.Findings – It was found that the top three criteria for SMS implementation were “client requirement” “insurance company requirement” and “employee requirement”. Both “safe...

The nonlinearity parameter B/A has been determined for various biological solutions and soft tissues using the thermodynamic and finite amplitude methods. Agreement between the two methods is better than 10% for the tissues and 1% for the solutions. Fat has a B/A value around 11, the highest among soft tissues studied. Other soft tissues including liver, muscle, brain, and heart muscle have B/A values close to 7. Based on the observed linear relation between the B/A value and solute concentration in protein solutions, and also the lack of dependence of the B/A value on solute molecular weight in dextran solutions, it is postulated that the nonlinearity in these solutions is due to solute-solvent interactions. The general trend of increasing B/A value with specimen structural hierarchy suggests that the nonlinearity of biological materials is related to this feature. These observations suggest the use of the nonlinearity parameter B/A in tissue characterization, particularly since structural alteration often attends the pathological state.

The nonlinearity parameter B/A has been determined for various biological solutions and soft tissues using both the thermodynamic and finite amplitude methods. This letter is to show that agreement achieved between the two methods is within a fraction of a percent for liquid samples and within 10% for the soft tissues studied.

The nonlinearity parameter B/A has been d etermined for tissue models (aqueous solutions of biological macromolecules) a nd for excised tissues from measurements of the fundamental pressure amplitude, at the source, and the second harmonic pressure amplitude, as a function of distance from the source. The general demeanor of the tissue model results is that B/A increases nearly linearly with solute concentration but, for a fixed concentration, is relatively insensitive to the molecular weight of the solute inolecules. Whole mammalian blood, whose dry weiqht consists largely of protein, exhibits a B/A value essentially that of protein solutions of the same dry weight concentration. Excised mammalian liver yields a B/A value significantly greater than blood, but homogenization of the tissue substantially reduces this B/A value. These findings suggest that the solutions become more nonlinear as the spacing distance between solute molecules decreases and that tissue architecture contributes to nonlinear behavior. It is felt that details of nonlinear ultrasonic propagation in living systems s hould contribute to further improvement of clinical diagnostic and therapeutic procedures.

Gas content of Pisum sativum root tips was determined by observing their density changes when subjected to hydrostatic pressure. The density of the root tissues at atmospheric pressure decreased with distance from the tip. Gas content of the meristem was less than 0.05% total tissue volume. Gas content increased with distance from the tip, approaching 1% at a distance of 4 mm from the tip.

The propagation of nonlinear ultrasonic waves in aqueous solutions of biological macromolecules (tissue models) has been studied by making measurements of the fundamental at the sound source and the second harmonic as a function of distance from the source. These studies show that the nonlinearity parameter B/A for bovine serum albumin and hemoglobin solutions increases nearly linearly with concentration from 5.2 for water to 7.3 for a 40% solution, suggesting that the solution becomes more nonlinear as the spacing distance between molecules decreases. Solutions of dextran molecules also have been studied from the monomer to a molecular weight of 2 000 000 Daltons showing that the nonlinearity parameter, for fixed concentration, is relatively insensitive to molecular weight. Measurements have also been made in whole mammalian blood which exhibits a nonlinearity parameter in proportion to its dry weight which consists largely of protein. These findings suggest that details of nonlinear acoustic propagation in living systems may contribute to further improvement in clinical diagnostic procedures. [This research was supported by a grant from the National Science Foundation.]

The phenomenon of thermal lesion production in tissues by unfocused ultrasound has been modeled under the assumptions (1) that damage to the tissues is the result of a chemical rate process and (2) that the time–temperature exposure of the tissue results from a competition between the rate of heat generation by absorption of ultrasonic energy and thermal diffusion. The model was tested by observing thresholds for color change in samples of excised bovine liver at 6 cm from a 2.25-MHz, 1.27-cm-diam piston source and 11.5 cm from a 4.4-MHz, 1.27-cm source. The observations disagreed sharply with predictions of the linear model. However, after recognition of the fact that finite amplitude phenomena modify the effective absorption coefficients of the tissues, the model gives excellent predictions of observed thresholds simply by using intensity dependent values of the absorption coefficients in the numerical calculations. Thermoelectric and radiation force methods were used to demonstrate the nonlinear absorption phenomenon in excised liver. In contrast with the case of focused ultrasound, the thresholds for lesion formation by unfocused sources (1) occur at lower intensities, (2) are strongly dependent upon frequency, and (3) because acoustic saturation in the coupling medium imposes lower limits on tissue intensities for unfocused than for focused ultrasound, unfocused lesions are limited to relatively long exposure times.

Examples of nonlinear acoustic phenomena in water in the range of frequencies and intensities of interest for biomedical ultrasound are provided. Total intensities, including all harmonics generated in the medium have been measured with a spherical radiometer. The fundamental component of the waves have been measured with a miniature probe hydrophone and low pass filter. Simple adaptation of the theory summarized in a companion paper leads to predictions which are in excellent agreement with the observations. The illustrated phenomena must be considered in studies of the biological effects of ultrasound as well as in the applications of ultrasound in medicine.

The growth rate of roots is reduced by exposure to ultrasound at 10 W/cm2 for 1 min. The reduction is somewhat greater at 1 MHz than at 5 MHz. A hydrostatic pressure of 30 atm reduced, but did not eliminate, the effect of ultrasound on growth. The frequency and pressure dependence taken together with earlier observations support the postulate that a cavitationlike mechanism is at least partly responsible for the action of ultrasound on the growth of these developing plant tissues.

Histological studies (7) on pea roots sonicated by a broad beam of ultrasound indicated that most of the damage occurs in the elongation region. There is little microscopic evidence of cell destruction in the meristem, and yet this region of dividing cells shows a marked cytokinetic response to sonication. Indirect effects of ultrasound were therefore suspected to exist.