Retention and Survival Optimization of Juvenile Green Mussel (Perna Viridis) by Using Substrate from Seaweed Extract

Highlight ResearchThe qualitative bioactive assay on terpenoid compound of six macroalgae species were tested.The effect of six macroalgae extracts as inducer mediating settlement to juvenile Perna viridis were observed.Three macroalgae species were potentially promote the retention of juvenile P. viridisAbstractThe low retention of juvenile of green mussels (Perna viridis) in the aquaculture holding system has become a constraint for its production. The depress number of juvenile mussel on the collector rope might be caused due to both limited spawning season and their secondary settlement behaviour. Therefore, providing suitable substrate which able to improve green mussel seed retention is required. One of the solutions is by applying inducer mediating settlement as substrate enrichment in order to optimize the retention of juvenile P. viridis. The potential substrates thought to have these inductive activities is seaweed. Seaweed bioactive compound which may improve juvenile mussel retention is terpenoid. Six seaweed extracts used in the current study and the terpenoid of these six macroalgae species were tested. Qualitatively all six seaweed showed a positive result on the terpenoid compound. The retention and survival of juvenile green mussel observed by using 20 conical tanks with a complete randomized design experiment. Each of the seaweed species tested separately comparing with three other experimental treatments under 24 h observation time, A (rope), B (rope + PhytagelTM), C (rope + PhytagelTM l+ solvent), D (rope + PhytagelTM + seaweed extract), it made four experimental treatments with 5 times replications. The result indicated a variation pattern on the retention of juvenile mussels according to the experimental substrate. The juvenile mussels were preferably settled on enriched substrate of G. latifolium and S. polycystum, extracts (p<0.05). Adding seaweed extracts on the substrate did not affect the mussels survival (p>0.05).

Nonlinear buckling optimization technique to predict critical imperfection wavelength of combined liquid-filled steel conical tanks

The shape of the imperfection induced by welding has an influence on the buckling resistance of thin shell structures, and many previous studies have come up with various models to estimate the critical imperfection shape. The aim of the current study is to assess the adequacy of three different approaches available in the literature, which consider that the imperfection wavelength matching the first buckling mode of a perfect tank to be the critical one. The first approach is based on buckling formulae calculated using a linear eigenvalue analysis performed on extensive experimental results of buckling of conical shells. The second approach assumes the critical wavelength, in view of the buckling mode profile detected from finite element analysis, as the distance between the inflection points of the elastic curve of the first buckling mode of a perfect tank. The third approach estimates the critical wavelength as double the distance between maximum and minimum points of the elastic curve. To determine the optimum wavelength that would lead to the minimum buckling capacity of the tank, the current study is conducted numerically by coupling a nonlinear finite element model, developed in house, and a direct search optimization technique. The results obtained from this numerical tool show good agreement with the first and the second approaches, which proves the adequacy of these two approaches in estimating the critical wavelength of the governing buckling mode, while the third approach yields a wavelength that overestimates the buckling capacity of the tank.

Effect of yeast harvest moment on a brewing process in beer produced on an industrial scale

The aim of this study was to determine the effect of yeast harvest timing on the process performance, total yeast count and the content of volatile components in beer. The experiments were performed on an industrial scale with fermentation and maturation conducted in three fermentation tanks with a capacity of 3800 hl (cylindro-conical tanks – CCT). All processes were carried out using the same technological conditions. The worts were aerated with sterile air and yeast after the second fermentation (third generation) was added. The duration of the maturation phase and the processes of the yeast harvest were conducted at different times (1^st, 4^th and 6^th day) after finishing the primary fermentation process. During fermentation and maturation, changes in the contents of the extract, yeast, and volatile components were investigated. These experiments showed that the use of different times during yeast harvest had a significant impact on the course of fermentation and maturation and impact on the total yeast count during the maturation process and on the amount of volatile components in beer. With a delay in the start of yeast cropping, the content of acetaldehyde and vicinal diketones decreased and the content of esters increased. The timing of the yeast crop significantly influenced the final beer quality.

Liquid Induced Vibrations of Truncated Elastic Conical Shells with Elastic and Rigid Bottoms

A method of estimating natural modes and frequencies of vibrations for elastic shells of revolution conveying a liquid is proposed. The vibration modes of the liquid-filled elastic shells are presented as linear combinations of their own vibration modes without liquid. The explicit expression for fluid pressure is defined using Bernoulli’s integral and potential theory suppositions. Non-penetration, kinematic, and dynamic boundary conditions are applied at the shell walls and on a free liquid surface, respectively. The solution of the hydro-elasticity problem is found out using an effective technique based on coupled finite and boundary element methods. Computational vibration analysis of elastic truncated conical shells with different fixation conditions is accomplished. Sloshing and elastic walls frequencies and modes of liquid-filled truncated conical tanks are estimated. Both rigid and elastic bottoms of shells are considered. Some examples of numerical estimations are provided to testify the efficiency of the developed method

Optimum design of composite conical tanks under hydrostatic pressure

Elevated tanks are used all over the world to store water for times of shortage. These tanks can be made of steel, reinforced concrete, or composite, that is, concrete and steel. Composite tanks consist of an external steel shell attached to an internal reinforced concrete wall through steel studs. Composite conical tanks combine the advantages of reinforced concrete and steel tanks as they resist efficiently both tensile and compressive stresses. A comparison showed that the material cost of composite conical tanks is significantly less than that of steel or reinforced concrete tanks having the same layout dimensions. A numerical tool is developed to obtain the optimum design of composite conical tanks under hydrostatic pressure incorporating both finite element and genetic algorithm techniques. This tool is used to obtain the optimum design of a case study composite conical tank that was recently constructed. The developed optimization tool provides the thicknesses of the concrete and steel walls as well as the stud configuration corresponding to the minimum material cost. A comparison between the optimized and unoptimized case study composite tank revealed that a reduction of 32% in the material cost can be achieved. A sensitivity analysis is conducted by changing the price of concrete, steel plate, and studs by (±) 50% of the datum prices and obtaining the corresponding optimum design variables. This analysis showed that the optimum thicknesses of the concrete wall and steel shell as well as studs’ configuration are significantly sensitive to the change in the material prices.