Some aspects of numerical simulation for lamb wave propogation in composite laminates

Some aspects of numerical simulation of Lamb wave propagation in composite laminates using the finite element models with explicit dynamic analysis are addressed in this study. To correctly and efficiently describe the guided-wave excited/received by piezoelectric actuators/sensors, effective models of surface-bounded flat PZT disks based on effective force, moment and displacement are developed. Different finite element models for Lamb wave excitation, collection and propagation in isotropic plate and quasi-isotropic laminated composite are evaluated using continuum elements (3-D solid element) and structural elements (3-D shell element), to elaborate the validity and versatility of the proposed actuator/sensor models.

Propagation characteristics of lamb waves in stringer-stiffened panels

Stringer-stiffened plate-like structure is a typical engineering structure and its structural integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the previous studies, the specimens were relatively simple. In this paper, the above mentioned method was extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic simulation was applied to investigate the Lamb wave propagation characteristics due to the existence of stringer with the consideration of its material and geometric configurations.

Dietary manipulation of muscle long-chain omega-3 and omega-6 fatty acids and sensory properties of lamb meat

The effects of dietary manipulation of muscle long-chain omega-3 fatty acids (FA) on sensory properties of cooked meat in second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs were evaluated. Lambs fed dietary supplements of fish meal (FM, Exp. 1) and fish oil (FO, Exp. 2) showed moderately (P<0.01) and markedly (P<0.001) increased muscle long-chain omega-3 FA content compared with those fed the basal diet of lucerne chaff and oat chaff. Protected canola seed (PCS, Exp. 1) significantly (P<0.001) increased omega-6 FA content of the longissimus muscle. In each of the 2 experiments (1 and 2), after being fed experimental diets for 6 weeks lambs were slaughtered at a commercial abattoir. At 24 h post-mortem (PM) the semitendinosus and biceps femoris muscles were removed from animals and stored at −20&deg;C until evaluation of sensory properties using experienced panel members. The muscle samples were stored for 3 (Exp. 1) and 12 (Exp. 2) months then removed, thawed and cooked for sensory evaluation. The meat samples were cooked under standardized conditions in a convection microwave at 180&deg;C (20–25 min) to an internal temperature of 75&deg;C. Cooked samples were tested for flavour, aroma, juiciness and overall palatability. The significant increase in muscle long-chain omega-3 with FM (Exp. 1 and 2) and FO (Exp. 2) or omega-6 FA with PCS (Exp. 1) were not detrimental to sensory panel evaluations of flavour or aroma of cooked meat when compared with the basal diet. However, meat from FM (Exp. 1) had lower juiciness and FO (Exp. 2) had lower overall palatability. Protected sunflower meal protein with FO (Exp. 2) significantly lowered ratings for flavour, juiciness and overall palatability. Lamb meat with increased levels of long-chain omega-3 FA can be produced without altering the sensory quality (flavour or aroma) of the cooked meat.

Comparison of the color stability and lipid oxidative stability of fresh vacuum packaged lamb muscle containing elevated omega-3 and omega-6 fatty acid levels from dietary manipulation

A series of three experiments were conducted with second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs to evaluate the effects of dietary treatments on manipulation of muscle long-chain (LC) omega-3 fatty acids (FA) on the color stability and oxidative stability of fresh and vacuum packaged lamb. At the end of 7-, 6- and 6-week experimental periods for experiments (Exp.) 1–3 respectively, lambs were slaughtered at a commercial abattoir. At 24 h post-mortem, muscle longissimus lumborum (LL) and longissimus thoracis (LT) were removed and evaluated for color and lipid oxidative stability under specified commercial storage and display condition. Of the dietary supplements used, fish meal and fish oil moderately (P<0.01) and markedly (P<0.001) increased muscle omega-3 FA content, while both protected canola seed (P<0.001) and protected sunflower meal protein significantly (P<0.02) increased muscle omega-6 FA content or ratio of omega-6/omega-3 of the longissimus muscle. In all experiments, the substantial increase (P<0.001) in muscle LC omega-3 and omega-6 FA had no consistent significant effect on color values (redness (a*), yellowness (b*) and lightness (L*)) for fresh and vacuum packaged lamb over a 6-day display period. Lipid oxidation, determined by the levels of thiobarbituric acid reactive substances (TBARS) indicated the enrichment of muscle polyunsaturated fatty acid (PUFA) levels in lambs did not produce significant differences resulting either from main treatment effects or for treatment×day×type interactions (where type was fresh and vacuum packaged). Present results demonstrated the color and lipid oxidative stability of lamb longissimus muscle during refrigerated display was not affected by enhanced levels of omega-3 and omega-6 FA due to dietary treatments.

Comparison of the color stability and lipid oxidative stability of fresh and vacuum packaged lamb muscle containing elevated omega-3 and omega-6 fatty acid levels from dietary manipulation

A series of three experiments were conducted with second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs to evaluate the effects of dietary treatments on manipulation of muscle long-chain (LC) omega-3 fatty acids (FA) on the color stability and oxidative stability of fresh and vacuum packaged lamb. At the end of 7-, 6- and 6-week experimental periods for experiments (Exp.) 1–3 respectively, lambs were slaughtered at a commercial abattoir. At 24 h post-mortem, muscle longissimus lumborum (LL) and longissimus thoracis (LT) were removed and evaluated for color and lipid oxidative stability under specified commercial storage and display condition. Of the dietary supplements used, fish meal and fish oil moderately (P<0.01) and markedly (P<0.001) increased muscle omega-3 FA content, while both protected canola seed (P<0.001) and protected sunflower meal protein significantly (P<0.02) increased muscle omega-6 FA content or ratio of omega-6/omega-3 of the longissimus muscle. In all experiments, the substantial increase (P<0.001) in muscle LC omega-3 and omega-6 FA had no consistent significant effect on color values (redness (a*), yellowness (b*) and lightness (L*)) for fresh and vacuum packaged lamb over a 6-day display period. Lipid oxidation, determined by the levels of thiobarbituric acid reactive substances (TBARS) indicated the enrichment of muscle polyunsaturated fatty acid (PUFA) levels in lambs did not produce significant differences resulting either from main treatment effects or for treatment×day×type interactions (where type was fresh and vacuum packaged). Present results demonstrated the color and lipid oxidative stability of lamb longissimus muscle during refrigerated display was not affected by enhanced levels of omega-3 and omega-6 FA due to dietary treatments.

Comparison of the color stability and lipid oxidative stability fo fresh and vacuum packaged lamb muscle containing elevated omega-3 and omega-6 fatty acid levels from dietary manipulation

A series of three experiments were conducted with second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs to evaluate the effects of dietary treatments on manipulation of muscle long-chain (LC) omega-3 fatty acids (FA) on the color stability and oxidative stability of fresh and vacuum packaged lamb. At the end of 7-, 6- and 6-week experimental periods for experiments (Exp.) 1–3 respectively, lambs were slaughtered at a commercial abattoir. At 24 h post-mortem, muscle longissimus lumborum (LL) and longissimus thoracis (LT) were removed and evaluated for color and lipid oxidative stability under specified commercial storage and display condition. Of the dietary supplements used, fish meal and fish oil moderately (P<0.01) and markedly (P<0.001) increased muscle omega-3 FA content, while both protected canola seed (P<0.001) and protected sunflower meal protein significantly (P<0.02) increased muscle omega-6 FA content or ratio of omega-6/omega-3 of the longissimus muscle. In all experiments, the substantial increase (P<0.001) in muscle LC omega-3 and omega-6 FA had no consistent significant effect on color values (redness (a*), yellowness (b*) and lightness (L*)) for fresh and vacuum packaged lamb over a 6-day display period. Lipid oxidation, determined by the levels of thiobarbituric acid reactive substances (TBARS) indicated the enrichment of muscle polyunsaturated fatty acid (PUFA) levels in lambs did not produce significant differences resulting either from main treatment effects or for treatment×day×type interactions (where type was fresh and vacuum packaged). Present results demonstrated the color and lipid oxidative stability of lamb longissimus muscle during refrigerated display was not affected by enhanced levels of omega-3 and omega-6 FA due to dietary treatments.

Quantitative assessment of through-thickness crack size based on Lamb wave scattering in aluminium plates

The interaction of Lamb wave modes at varying frequencies with a through-thickness crack of different lengths in aluminium plates was analysed in terms of finite element method and experimental study. For oblique-wave incidence, both numerical and experimental results showed that the wave scattering from a crack leads to complicated transmission, reflection and diffraction accompanied by possible wave-mode conversion. A dual-PZT actuation scheme was therefore applied to generate the fundamental symmetrical mode (S0) with enhanced energy to facilitate the identification of crack-scattered wave components. The relationship between crack length and the reflection/transmission coefficient obtained with the aid of the Hilbert transform was established, through which the crack length was quantitatively evaluated. The effects of wavelength of Lamb waves and wave diffraction on the properties of the reflection and transmission coefficients were analysed.

Activation of the hypothalamo-pituitary-adrenal axis by isolation and restraint stress during lactation in ewes : effect of the presence of the lamb and suckling

We investigated the effect of the presence and absence of lambs and suckling by lambs to attenuate activation of the hypothalamo-pituitary-adrenal (HPA) axis to isolation and restraint stress in lactating sheep. In experiment 1, blood samples were collected every 10 min from nonlactating (n = 5) and lactating (n = 5) ewes for 4 h before and during stress. In experiment 2, ewes (n = 6) were allocated to 1) nonlactating, 2) lactating with lambs absent, 3) lactating with lambs present but unable to suckle, and 4) lactating with lambs present and able to suckle. Blood samples were collected over 8 h with no stress (control day) and for 4 h before and 4 h during stress (stress day). In experiment 1, the mean (±SEM) cortisol concentrations increased significantly (P < 0.05) in nonlactating ewes during stress but did not change in lactating ewes. In experiment 2, cortisol did not vary on the control day or pretreatment of the stress day but increased (P < 0.05) during stress in all groups except lactating ewes with lambs present and able to suckle. The greatest cortisol response occurred in nonlactating ewes followed by lactating ewes with lambs absent and lactating ewes with lambs present but unable to suckle. During stress, the ACTH concentrations increased (P < 0.05) in nonlactating ewes and lactating ewes with lambs absent but not in lactating ewes with lambs present. We conclude that the activity of the HPA axis during isolation and restraint is reduced in lactating ewes and that the presence of lambs increases this level of attenuation.

Effect of migration on food habits of Somali women living as refugees in Australia

This study aimed to assess the dietary changes that occur for migrants moving from a low-income to a high-income country. The sample included 45 females who had migrated to Australia from Somalia within the past 5years (1996-2001). The data for the study was derived from structured interviews conducted by a bilingual interviewer and anthropometry. Usual dietary intake and frequency of consumption of 54 foods were determined both for Australia (current home) and for Somalia (previous home). In Australia, subjects maintained the structure of the diet from their country of birth. They did increase their consumption of some processed food, such as instant noodles, crisps, and pizza. However, there was little evidence that the subjects adopted ready or partially prepared meals or takeaway meals. A significant addition to the diet in Australia was the use of breakfast cereals. Significant substitutions were of ready-baked bread for traditional bread and lamb for camel meat. The mean BMI of the sample was 27.4kg/m². Sixty percent of the sample were overweight or obese (BMI>25). Some of the dietary changes observed may be consistent with increased energy intake and altered nutrient density. Given the association between transition to a high-income diet and obesity, it is important that migrants are encouraged to retain the best of their traditional diet while adopting healthy foods from host country.

Green decisions : demographics and consumer understanding of environmental labels

This research examined the demographic profiles of Australian green consumers in relation to their satisfaction of environmental labelling. It examined consumers’ understanding of labelling and empirically investigated the association of demographic profile of consumers with their attitudes towards such labels. The results indicated that some of the demographic variables were significant, which is largely consistent with earlier findings by other researchers in this area. Label dissatisfaction was higher in the older and middle age respondents. However, some respondents disagreed that labels were accurate while commenting that labels were easy to understand. The key issue arising from the findings is that in order to provide perception of accuracy in labels, it is an option to use Type I or Type III labelling on products. These labels are, arguably, more credible because they are endorsed by third party labelling experts. This would come at a cost and for green products that use third party labelling, they will also have to bear in mind to keep the prices competitive.

Assessment of delamination in composite beams using shear horizontal (SH) wave mode

Interaction of Lamb waves with structural damage can lead to wave mode conversion. In this study, the shear horizontal (SH) wave, from the mode conversion of the fundamental symmetric Lamb wave (S0), was used for quantitative identification of delamination in composite beams, based on advanced signal processing using an inverse approach. SH wave propagation under various delamination conditions in CF/EP beams made of orthotropic plain woven fabrics was simulated, and signal characteristics were extracted in terms of the concept of digital damage fingerprints (DDF). With the aid of an artificial neural algorithm, the relation between the DDF of delamination-scattered SH mode and damage parameters was calibrated, whereby the occurrence, location and size of delamination in the composite beams were assessed. The approach was experimentally validated, and the results demonstrate the effectiveness of SH mode for quantitative damage evaluation of composite structures.

Green products and corporate strategy : an empirical investigation

Purpose – The purpose of the study is to examine the influence of multiple factors on the green purchase intention of customers in Australia.

Design/methodology/approach – A conceptual model is proposed and was subjected to empirical verification with the use of a survey of metropolitan and regional households in Victoria, Australia. The data were analyzed using both descriptive measures and exploratory factor analysis to identify and validate the items contributing to each component in the model. AMOS structural modeling was used to estimate the measure of respondents' overall perception of green products and their intention to purchase.

Findings – The results indicate that customers' corporate perception with respect to companies placing higher priority on profitability than on reducing pollution and regulatory protection were the significant predictors of customers' negative overall perception toward green products. The only positive contribution to customers' perception was their past experience with the product. Other factors including the perception of green products, product labels, packaging, and product ingredients did not appear to influence customers' perception. The results also indicate that customers are not tolerant of lower quality and higher prices of green products.

Research limitations/implications – The knowledge of the overall perception formation about green products and its predictors provides management with the facility to identify and implement strategies that may better influence the change of attitude by customers. Corporations can also benefit from the identification of the types of information required to enable management to influence this process of perception formation.

Originality/value – The present findings contributes to an understanding of the antecedents of green purchasing and highlight that green customers rely more on personal experience with the product than the information provided by the marketer.