Comparison of industrial-scale tubular photobioreactor to FRP (fiberglass reinforced plastic) panel photobioreactor on outdoor culture of Nannochloropsis oculata in the marine hatchery

Microalgal culture is a key procedure in marine fish hatcheries, but this activity is far from optimized and has several problems remain to be solved. Nannochloropsis oculata are important to live feed organisms, which are used to rear the larvae of marine finfish. N. oculata were cultivated in tubular PBR and FRP panel PBR in a greenhouse. Tubular PBR was reached 701.7 x 106 cells mL-1 as its maximum cell density and FRP panel PBR was reached 245 x 106 cells mL-1 as maximum. Also, estimated maximum dry weights of tubular and FRP panel PBRs were calculated as 3.249 g L-1 and 1.47 g L-1, respectively. Consequently, tubular PBR was showed that it is more efficient than FRP panel PBR in this study.

On the Directivity of Acoustic Waves Generated by the Angle Beam Wedge Actuator in Thin-Walled Structures

The paper aims to develop improved acoustic-based structural health monitoring (SHM) and nondestructive evaluation (NDE) techniques, which provide the waves directivity emitted by the angle beam wedge actuators in thin-walled structures made of plastic materials and polymeric composites. Our investigation includes the dispersive analysis of the waves that can be excited in the studied plastic panel. Its results allowed to find two kinds of generated acoustic waves—anti-symmetric Lamb waves (A0) and shear horizontally polarized SH waves (SS0). The bounds of the chosen frequency range for the experimental and numerical studies were accepted as a compromise between the desire to obtain a high defect resolution by generating short waves, their adjustable directivity, and maximum propagation length. The finite element model for the transducer was built by using the results of an actuator structure experimental study. The frequency response functions for the actuator current and oscillation amplitude of the footprint surface demonstrated good agreement. The found eigenfrequencies of the actuator’s structure were used for the numerical and experimental study of the Lamb and SH wave generation and propagation in a thin-walled plastic panel. Our results convincingly demonstrated the satisfactory directivity of the actuated waves at their excitation on the frequencies that corresponded to the natural modes of the actuator oscillation. The authors assume that an efficient use of the proposed technique for other analyzed quasi-isotropic materials and applied actuators can be provided by preliminary research using a similar approach and methods presented in this article.

On the Directivity of Acoustic Waves Generated by the Angle Beam Wedge Actuator in Thin Walled Structures

The paper is aimed to develop an improved acoustic-based Structural Health Monitoring (SHM) and Non-Destructive Evaluation (NDE) techniques, which provide the waves directivity emitting by the angle-beam wedge actuators in the thin-walled structures made of plastic materials and polymeric composites. Our investigation includes the dispersive analysis of the waves that can be excited in the studied plastic panel. Its results allowed to find two kinds of the generated acoustic waves - anti-symmetric Lamb waves A0 and shear horizontally polarized SH waves SS0. The bounds of the chosen frequency range for the experimental and numerical studies were accepted as a compromise between the desire to obtain high defects resolution by generating short waves, their adjustable directivity and maximum propagation length. The finite element model for the transducer was built by using the results of actuator structure experimental study. The frequency response functions for the actuator current and oscillation amplitude of the footprint surface demonstrated good agreement. The found eigenfrequencies of actuator's structure were used for the numerical and experimental study of the Lamb and SH wave generation and propagation in a thin-walled plastic panel. Our results convincingly demonstrated the satisfactory directivity of the actuated waves at their excitation on the frequencies that corresponded to the natural modes of the actuator oscillation. The authors assume that an efficient use of the proposed technique for other analyzed quasi-isotropic materials and applied actuators can be provided by a preliminary research using the similar approach and methods presented in this article.

Shrinkage Analysis of Injection-Compression Molding for Transparent Plastic Panel by 3D Simulation

Injection molding which is adopted to fabricate transparent plastic panel has merits such as high efficiency and low cost, and is being used widely. However, at the end of injection molding process, product may be affected by uneven shrinkage and as a result, bring defects such as warp to the final part. This can greatly damage its mechanical and optical quality. Injection-compression molding(ICM) can significantly minimize these defects. In the present paper, 3D model and coupled calculation method of flow, temperature and pressure are used to simulate the process of ICM for an irregular geometric transparent plastic panel. This method can not only reconstruct 3D flow front, temperature and pressure field of ICM process in a much more realistic way, but also more fully demonstrate the length of 3D fiber flow line(FFL) and the variation of shrinkage rate and its homogenize process. Due to such improved algorithm, great improvement has been made to accurately calculate the shrinkage rate in depth of the panel and predict its warp data, in comparison to the traditional temperature-volume contraction index method, which has important practical value to guide and design the technological process of ICM.

Methode zur Untersuchung der Lernfähigkeit von Kälbern in Gruppenhaltung und Ergebnisse bei visuellen Differenzierungsaufgaben

Title of the paper: Method to assess the learning ability of group-housed calves and results of visual discrimination tasks Assessing the sensory capacity and learning ability of farm animals will be of increasing importance for the evaluation of animal welfare in order to develop new efficient farming technologies which seriously consider the animals' well-being. The more-arm-maze test using optic signalling proved to be a useful method to assess the learning ability of singel or group-housed calves. Each test box consisted of 3 Stands per calf arranged side by side (stand dimensions: 1.00 m long, 0.30 m wide and 1.50 m high, wooden walls). The Stands could be distinguished by coloured lamps or black visual patterns of different shapes, projeeted on a white plastic panel above the entrance as Stimuli. Chosing the right (conditioned) Stimulus the calves were rewarded by milk (unconditioned Stimulus) when suckling at the dispenser. Given a random expectation of 33%, the calves reached at least 70% correct choiees already at the 4th test day.