Location effects of passive damping material in cross-ply laminates on natural frequency and mode shape

This study presents an experimental investigation of the free vibration of cantilevered composite laminated plates with embedded passive damping material at different stages. A total of five composite laminated plates are considered. The lay-up sequences for the five composite laminated plates with and without two embedded layers of passive damping material are [90°/0°/90°/0°]s, [90°/0°/90°/0°/d]s, [90°/0°/90°/d/0°]s, [90°/0°/d/90°/0°]s, and [90°/d/0°/90°/0°]s. The passive damping material employed is a 3M material, SJ-2015 ISD 112, with peak damping properties in the ambient temperature range of 32°F to 140°F. The composite material used is a carbon fiber (977-2)/epoxy resin (IM7). The effect of the passive damping system employed in this study for the composite plates are discussed. Modal testing is performed on these plates to determine resonant frequencies, amplitude and mode shape information. The study included white noise and sinusoidal dynamic testing techniques, a PC computer based data acquisition system, and a virtual instrument dynamic analysis. The different locations of the passive damping material in the cross-ply laminated plates resulted in degradation effects on the natural frequency, damping and mode of shape

Potential impact of prickly pear cactus flour and Salix babylonica extract on cecal fermentation and methane production in horses

The cecal gas (GP) and methane (CH4) production and cecal fermentation kinetics when corn grain (CG) was replaced with prickly cactus (PC) in a horse’s diet at different levels of Salix babylonica (SB) extract was investigated. Three total mixed rations where CG was replaced with PC at three levels (/kg): 0 g (Control), 75 g (PC75) or 150 g (PC150) were prepared and SB extract added at four levels: 0, 0.6, 1.2 and 1.8 mL/g dry matter (DM) of substrates. No ration type 9 SB extract dose interaction was observed (P [0.05) for GP kinetics and CH4 production. Increasing the level of PC in the ration quadratically increased (P \0.01) the asymptotic GP and decreased (P\0.01) the rate and lag time of GP. Increasing the level of PC in the ration, increased GP values (P\0.05). Increasing the level of SB extract linearly decreased (P = 0.001) the lag time of GP of all diets without affecting the asymptotic GP or the rate of GP. Ration type and SB level had no effect (P [0.05) on CH4 production; however, at 36 h of incubation, SB extract decreased CH4 production. The rations PC75 and PC150 increased cecal pH compared with the control ration. The PC150 ration had the highest (P\0.05) DM degradability, short chain fatty acids production, and gas yield after 24 h of incubation, with no effect (P[0.05) of SB inclusion on all investigated fermentation kinetic parameters. It is concluded that increasing the level of PC in the diet of horse and replacing CG up to 60%, increased GP and improved cecal fermentation kinetics without affecting CH4 production. Inclusion of S. babylonica extract in the tested rations had weak effects on fermentation kinetics although it decreased the lag time of GP

Hybrid Damping System for an Electronic Equipment Mounting Shelf

The objective of this study was to design and construct a vibration control system for an electronic equipment shelf to be evaluated in the NASA Dryden FTF-II. The vibration control system was a hybrid system which included passive and active damping techniques. Passive damping was fabricated into the equipment shelf using ScothDamp(trademark) damping film and aluminum constraining layers. Active damping was achieved using a two channel active control circuit employing QuickPack(trademark) sensors and actuators. Preliminary Chirp test results indicated passive damping smoothed the frequency response while active damping reduced amplitudes of the frequency response for most frequencies below 500Hz

Hybrid Damping System for an Electronic Equipment Mounting Shelf

The objective of this study was to design and construct a vibration control system for an electronic equipment shelf to be evaluated in the NASA Dryden FTF-11. The vibration control system was a hybrid system which included passive and active damping techniques. Passive damping was fabricated into the equipment shelf using ScothDamp(trademark) damping film and aluminum constraining layers. Active damping was achieved using a two channel active control circuit employing QuickPack(trademark) sensors and actuators. Preliminary Chirp test results indicated passive damping smoothed the frequency response while active damping reduced amplitudes of the frequency response for most frequencies below 500Hz

Strong effects of uniaxial pressure and short-range correlations in Cr2Ge2Te6

Cr2Ge2Te6 is a quasi-two-dimensional semiconducting van der Waals ferromagnet down to the bilayer with great potential for technological applications. Engineering the critical temperature to achieve room-temperature applications is one of the critical next steps on this path. Here, we report high-resolution capacitance dilatometry studies on Cr2Ge2Te6 single crystals which directly prove significant magnetoelastic coupling and provide quantitative values of the large uniaxial pressure effects on long-range magnetic order (∂TC/∂pc=24.7 K/GPa and ∂TC/∂pab=−15.6 K/GPa) derived from thermodynamic relations. Moderate in-plane strain is thus sufficient to strongly enhance ferromagnetism in Cr2Ge2Te6 up to room temperature. Moreover, unambiguous signs of short-range magnetic order up to 200 K are found

Magnetic properties of triangular lattice antiferromagnets Ba3RB9O18 (R = Yb, Er)

Frustration, spin correlations and interplay between competing degrees of freedom are some of the key ingredients that underlie exotic states with fractional excitations in quantum materials. Rare-earth based two dimensional magnetic lattice wherein crystal electric field, spin-orbit coupling, anisotropy and electron correlation between rare-earth moments offer a new paradigm in this context. Herein, we present crystal structure, magnetic susceptibility and specific heat accompanied by crystal electric field calculations on the polycrystalline sample of Ba3RB9O18 (R = Yb, Er) in which R3+ ions form a perfect triangular lattice without anti-site disorder. The localized R3+ spins show neither long-range order nor spin-glass state down to 1.9 K in Ba3RB9O18. Magnetization data reveal a pseudospin Jeff = 1/2 ( Yb3+) in the Kramers doublet state and a weak antiferromagnetic interaction between Jeff = 1/2 moments in the Yb variant. On the other hand, the effective moment {\mu}eff = 8.8 {\mu}B was obtained from the Curie-Weiss fit of the low-temperature susceptibility data of Er variant suggests the admixture of higher crystal electric field states with the ground state. The Curie-Weiss fit of low-temperature susceptibility data for Er system unveils the presence of a relatively strong antiferromagnetic interaction between Er3+ moments compared to its Yb3+ analog. Ba3ErB9O18 does not show long-range magnetic ordering down to 500 mK. Furthermore, our crystal electric field calculations based on magnetization data of Ba3ErB9O18 suggest the presence of a small gap between the ground and first excited Kramers doublets. The broad maximum around 4 K in magnetic specific heat in zero-field is attributed to the thermal population of the first CEF excited state in Ba3ErB9O18, which is consistent with our CEF calculations

Digestion, growth performance and caecal fermentation in growing rabbits fed diets containing foliage of browse trees

[EN] This study aimed to evaluate the effect of feeding dried foliage (leaves and petioles) of Acacia saligna, Leucaena leucocephala or Moringa oleifera on the performance, digestibility, N utilisation, caecal fermentation and microbial profiles in New Zealand White (NZW) rabbits. One hundred weaned male NZW rabbits weighing 819.2±16.6 g and aged 35±1 d were randomly allocated into 4 groups of 25 rabbits each. Rabbits were fed on pelleted diets containing 70% concentrate mixture and 30% Egyptian berseem (Trifolium alexandrinum) hay (Control diet) or one of the other 3 experimental diets, where 50% of berseem hay was replaced with A. saligna (AS), L. leucocephala (LL) or M. oleifera (MO). Compared to Control diet, decreases in dry matter (DM; P=0.004), organic matter (P=0.028), crude protein (CP; P=0.001), neutral detergent fibre (P=0.033) and acid detergent fibre (P=0.011) digestibility were observed with the AS diet. However, DM and CP digestibility were increased by 3% with the MO diet, and N utilisation was decreased (P<0.05) with AS. Rabbits fed AS and LL diets showed decreased (P=0.001) average daily gain by 39 and 7%, respectively vs. Control. Feed conversion was similar in Control and MO rabbits, whereas rabbits fed AS diet ate up to 45% more feed (P=0.002) than Control rabbits to gain one kg of body weight. Caecal ammonia-N was increased (P=0.002) with LL, while acetic acid was decreased (P=0.001) with AS diet vs. other treatments. Caecal E. coli and Lactobacillus spp. bacteria counts were decreased with MO by about 44 and 51%, respectively, vs. Control. In conclusion, under the study conditions, tree foliage from M. oleifera and L. leucocephala are suitable fibrous ingredients to be included up to 150 g/kg in the diets of growing rabbits, and can safely replace 50% of berseem hay in diets of NZW rabbits without any adverse effect on their growth performance. Foliage from M. oleifera had a better potential as a feed for rabbits than that from L. leucocephala. Although foliage from A. saliga may be also used at 150 g/kg in the diets of growing rabbits, this level of inclusion may result in reduced feed digestibility and growth performance.Abu Hafsa, S.; Salem, A.; Hassan, A.; Kholif, A.; Elghandour, M.; Barbabosa, A.; Lopez, S. (2016). Digestion, growth performance and caecal fermentation in growing rabbits fed diets containing foliage of browse trees. World Rabbit Science. 24(4):283-293. doi:10.4995/wrs.2016.4359.SWORD28329324

Utility of arylhydrazidoyl aryl ethers in heterocycles: A novel synthesis of aryloxypyridazines, phthalazines and thieno-[3,4-d]pyridazine derivatives

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Valorization of Caesalpinia coriaria Fruit Waste to Enhance the Ruminal Mitigation of Greenhouse Gases Production

La editorial tiene los derechos de autor y le solicito a hacer visibles la fecha técnica del artículo.The use of fruits waste from tanniniferous trees represents a new technology that aims to solve or mitigate greenhouse gases emission, and to increase the production of food of animal origin in an ecofriendly manner. This study aims to evaluate the production of methane and carbon dioxide, degradability by in vitro ruminal fermentation in goats diet supplemented with nuts (Caesalpinia coriaria Jacq. Willd.) for adoption by livestock farmers. Condensed tannins (CT) of C. coriaria inclusion rates were 0 (CT0 or control, no CT), 1.5 (CT1.5), 3.0 (CT3), 4.5 (CT4.5) and 6.0% (CT6) of the total mixed ration. All CT treatments reduced (linear, quadratic and cubic; P = 0.001) CH4, CO2 and H2 gases, and had some increasing effect on total biogas production. However, CT3 reduced greenhouse gases and had the highest biogas production. Addition of tannins from cascalote fruit waste (C. coriaria Jacq. Willd.) to goats diet at CT3 level reduced methane production, improved fermentation and ruminal degradability in vitro and has potential to be used as ecofriendly feed or feed additive

Influence of exogenous enzymes in presence of Salix babylonica extract on digestibility, microbial protein synthesis and performance of lambs fed maize silage

In Mexico, there are native trees that can be used as an alternative feed when forages are scarce and of poor quality in the dry season (Palma et al. 1995). However, the use of plants or their extracts as feed additives is restricted by their secondary compound content (Salem et al. 2014c): although the ideal concentrations can modify and support the utilization of nutrients in the rumen (Salem et al. 2014a, b, c), an inverse relationship between secondary compound concentration and animal performance has been observed (Vasta & Luciano 2011; Salem et al. 2011a, 2013).Sixteen Suffolk lambs with 29 ± 2·0 kg body weight were housed in individual cages for 60 days and allotted to four treatments in a completely randomized design to determine the effect of administration of Salix babylonica (SB) extract and/or exogenous enzymes (ZADO®) on lamb performance. Lambs were fed with 300 g/kg concentrate (160 g crude protein (CP)/kg, 13·4 MJ metabolizable energy (ME)/kg dry matter (DM)) and 700 g/kg maize silage (80 g/kg CP, 11·7 MJ ME/kg DM) as a basal diet (control). Another three treatments were tested; the SB extract was administered at 30 ml/day (SB) and exogenous enzymes ZADO® (i.e. an exogenous enzyme cocktail in a powder form) directly fed at 10 g/day (EZ), while the last treatment contained ZADO® at 10 g/day + SB extract at 30 ml/day (EZSB). Lambs of the treatment EZSB had the greatest average daily weight gain (ADG) and feed conversion throughout the period of the experiment. However, during the first 30 days SB was more effective for ADG than EZ and vice versa during the last 30 days of the experiment.Water consumption was greater for SB, followed by EZ and EZSB compared to the control. Intakes ofDMand organicmatter (OM) were the highest in EZSB followed by EZ, which had the greatest neutral detergent fibre, acid detergent fibre (ADF) and nitrogen (N) intakes. The EZSB treatment had the greatest DM and OM digestibilities compared to the other treatments; however, SB had the greatest ADF digestibility. Combination of EZ and SB had the best N balance. Allantoin, total purine derivatives (PD), allantoin : -creatinine ratio, and PD: creatinine ratio were increased in EZSB compared to the other treatments. However, EZ supplementation increased uric acid concentration, whereas the microbial N (g N/day) and metabolizable protein (g N/day) were increased in EZSB versus the other treatments. It can be concluded that addition of 10 g ZADO® in combination with S. babylonica extract at 30 ml/day in the diet of lambs increased feed intake, nutrient digestibility and daily gain, with a positive impact on the use of N and microbial protein synthesis