Search

Research has focused on alternative plant materials or additives that can be used instead of fish meal due to limited stocks and increased feed prices, although it is important for carnivorous fish species. Taurine is a functional amino acid supplemented to low fish meal diets to improve the growth performance of fish. In this study, eight experimental diets with 0%, 0.5%, 1% and 2% ratios of taurine supplemented (T0, T0.5, T1 and T2) high (HFM) and low fish meal (LFM) diets were prepared (defined as HFMT0, HFMT0.5, HFMT1, HFMT2, LFMT0, LFMT0.5, LFMT1 and LFMT2). The experiment was carried out in twenty-four 400 L rectangular fiberglass tanks conducted in a marine water system, and fish (initial mean weight of 23.5 g) were stocked in each tank. The nutrition trial was carried out for 90 days with three replicates. Meagre fed with the HFMT1 diet had a higher final mean weight (FMW) and specific growth rate (SGR) than fish fed with HFMT0 and all LFM diets. Including taurine in all LFM diets also enhanced growth performance. The FMW and SGR of fish fed the LFMT0.5 diet were similar when compared to HFMT0 (P>0.05) and increased compared to that of other LFM diets with taurine (P<0.05). Meagre fed the LFM0.5 diet had a lower feed conversion rate (FCR) than those provided for all HFM diets, although there was no significant difference between treatments. Dietary taurine has decreased the hepatosomatic index (HSI), viscerosomatic index (VSI) and total ammonia-nitrogen excretion (TAN), irrespective of taurine and fish meal levels. Including dietary taurine at both fish meal levels enhances the number of red blood cells (RBC) and whole-body amino acids of meagre. The most remarkable conclusion of this study is the inclusion of taurine in low fish meal diets improved growth performance and profitability in meagre, and the level of 0.5% has been recommended.

Improving the power and efficiency of 9xx-nm broad-area laser diodes has a great help in reducing the cost of laser systems and expanding applications. This letter presents an optimized epitaxial structure with high power and conversion efficiency. Laser diodes with 230 $\mu \text{m}$ emitter width and 5 mm cavity length deliver continuous-wave output power up to 48.5 W at 48 A, 30 °C, the highest power reported for 9xx-nm single emitter lasers so far. The slope efficiency is as high as 1.23 W/A due to a low internal optical loss of 0.31 cm−1 and a high internal efficiency of 96%. The maximum power conversion efficiency reaches 72.6% at 15.3 W and 67.3% at the operating power of 30 W under a heatsink temperature of 25 °C. Life test results show no failure in 1000 hours for 55 laser diodes.

ABSTRACT In this study, artificial neural network (ANN) and fuzzy logic (FL) models have been developed for predicting the compressive strength ([f.sub.c]) and dynamic modulus of elasticity ([E.sub.d]) of the [...]

ABSTRACT In this study, the alterations at the reinforcement steels embedded in corroded and not corroded reinforcement mortar specimens after high temperatures were investigated. These reinforced mortar specimens with 3 [...]

In the present study, the harmonic movement of fluid flow and the behaviour of elastic structure under this movement are investigated. Accordingly, a recently developed fluid-structure interaction method in which fluid and structure are simulated with smoothed particle hydrodynamics (SPH) and finite element method (FEM) is used. The interaction between fluid and the structure is satisfied with the contact mechanics. In order to validate the numerical model under harmonic movement, different experiments are used. First, the structure is assumed to be rigid and the pressures calculated on the structure are compared with the experimental data available in the literature. Similarly, free-surfaces are also validated with novel experiments carried out in the context of this study. In addition, the interaction between an elastic structure and fluid is investigated in the novel experiments in which a water tank having an elastic buffer in the middle is moved under harmonic horizontal movement and the deflection of the elastic buffer and free-surface profiles are measured. Comprehensive results are given for all validation cases. According to the results, the numerical method is successful and can be used in these types of problems.

There have been few experimental and numerical studies on damping effects in fluid-structure interaction (FSI) problems. Therefore, a comprehensive experimental study was conducted to investigate such effects. In experiments, a water column in a container was released and hit a rubber plate. It continued its motion until hitting a downstream wall where pressure transducers had been placed. The experiments were repeated using rubber plates with different thickness and material properties. Free-surface profiles, displacements of the rubber plates, and pressures were recorded. In addition, a numerical model was developed to simulate the violent interaction between the fluid and the elastic structure. Smoothed particle hydrodynamics (SPH) and finite element method (FEM) were used to model the fluid and the structure. Contact mechanics was used to model the coupling mechanism. The obtained numerical results were in agreement with the experimental data. We found that damping is a less important parameter in the FSI problem considered.

Exhaust emissions resulting from the motor vehicles have harmful and long lasting effects on both the human health and environment. Especially increasing concentrations of exhaust emissions in the closed environments and in the environments that cannot be sufficiently ventilated can cause damage on the human health and lead even to the death. The main harmful exhaust emissions based on the motor vehicles are gases such as CO (carbon dioxide), HC (hydrocarbons), and NOx (nitrogen oxides). In the circumstances of remaining under the influence of these gases, all the systems of the human body are generally get harmed. Therefore, the exhaust emission maps of the areas where there are the harmful exhaust emission concentrations in the high level, and the discharge methods of these gases in a very short space of time must be. In this study, the emission measurements have been carried out in four underground and five aboveground multi-storey car parks located in Istanbul. The effects on the human health of the measured fields were studied by the use of the results of the performed measurements, by comparing them with the maximum allowable concentration (MAC) and the threshold limit value - time weighed average (TLV – TWA) values. Taking into consideration all of the measurement results in the under-ground and above-ground multi-storey car parks, it is determined that the short-term use of the measured fields do not pose any risks in terms of human health. The suggestions regarding the improvement works of the car-parks were presented.

We have demonstrated a monolithic (fully fused), 1.2-kW, Yb-doped fiber laser with near-single-mode beam quality. This laser employs a new generation of high-brightness, fiber-coupled pump sources based on spatially multiplexed single emitters, with each pump providing 100 W at 915 nm within 0.15 NA from a standard 105/125 m fiber. The fiber laser is end pumped through the high-reflector FBG using a 19:1 fused-fiber pump combiner, eliminating the need for pump/signal combiners. The output wavelength is 1080 nm, with a linewidth of < 0.5 nm FWHM. A peak power of 1.5 kW was reached in modulated operation (1-ms pulse duration) with M2< 1.2.

The effect that geometrical resonances of orbiting internally reflecting rays have on the morphology-dependent resonances of microspheres is investigated heuristically and numerically using generalized Lorenz–Mie theory. Angularly resolved off-axis Gaussian beam elastic scattering spectra are presented. The results obtained show that the elastic scattering intensity of morphology-dependent resonances is noticeably enhanced in the vicinity of the geometrical resonance scattering angles.

Data are presented demonstrating a new lithographic vertical-cavity surface-emitting laser (VCSEL) technology, which produces simultaneous mode- and current-confinement only by lithography and epitaxial crystal growth. The devices are grown by solid source molecular beam epitaxy, and have lithographically defined sizes that vary from 3 m to 20 m. The lithographic process allows the devices to have high uniformity throughout the wafer and scalability to very small size. The 3 m device shows a threshold current of 310 A, the slope efficiency of 0.81 W/A, and the maximum output power of more than 5 mW. The 3 m device also shows single-mode single-polarization operation without the use of surface grating, and has over 25 dB side-mode-suppression-ratio up to 1 mW of output power. The devices have low thermal resistance due to the elimination of oxide aperture. High reliability is achieved by removal of internal strain caused by the oxide, stress test shows no degradation for the 3 m device operating at very high injection current level of 142 kA/cm2for 1000 hours, while at this dive level commercial VCSELs fail rapidly. The lithographic VCSEL technology can lead to manufacture of reliable small size laser diode, which will have application in large area 2-D arrays and low power sensors.

Data are presented demonstrating lithographic vertical-cavity surface-emitting lasers (VCSELs) and their scaling properties. Lithographic VCSELs have simultaneous mode- and current-confinement defined only by lithography and epitaxial crystal growth. The lithographic process of these devices allows getting uniform device size throughout a wafer and easy scaling to manufacture very small lasers. The semiconductor's high thermal conductivity enables the small lithographic VCSEL to have lower thermal resistance than an oxide-aperture VCSEL, while the lithographic fabrication produces high VCSEL uniformity even at small size. Very dense packing is also possible. Devices of 3 m to 20 m diameters are fabricated and scaling properties are characterized. 3 m lithographic VCSELs produce output power of 4.1 mW, with threshold current of 260 A and slope efficiency of 0.76 W/A at emission wavelength of ~980 nm. These VCSELs also have single-mode single-polarization lasing without the use of a surface grating, and have >25 dB sidemode- suppression-ratio up to 1 mW of output power. Lifetime tests demonstrate that 3 m VCSEL operates for hundreds of hours at high injection current level of 85 kA/cm2with 3.7 mW output power without degradation. Scaling properties and low thermal resistance of the lithographic VCSELs can extend the VCSEL technology to manufacturable and reliable small size lasers and densely packed arrays with long device lifetime.

There is a common belief among the majority of surgeons occupied with cleft lip–cleft palate repair that early one-stage simultaneous repair of hard and soft palates affects maxillofacial development adversely. This proposition has not been proven with long-term clinical studies. In this study, the effects of one-stage repair on the maxillofacial development of children with complete unilateral cleft lip–cleft palate were investigated, and the results were compared with those of the cleft children treated with conventional two-stage repair.