EXPERIMENTAL INVESTIGATION INTO THE EFFECTS OF REDUCED VERTICAL CENTRE OF GRAVITY OF AN ARTICULATED CONCRETE MATTRESS IN CURRENT FLOW

Author(s):  
A Neville ◽  
R McLaren ◽  
J Weber ◽  
C Chin ◽  
J Binns ◽  
...  

An articulated concrete mattress model has been utilised to investigate the effects of reduced vertical centre of gravity on the stability of a 400 series block. Experimental testing was conducted at the AMC CWC, Beauty Point. To determine the effects that a reduced centre of gravity has on stability, the 3 by 3 articulated concrete mattress model was subject to pure uniform current flow. The subsequent forces were analysed with a six degree of freedom underwater force sensor. In order to gain a range of real world scenarios, the experimental model was tested at six flow angles ranging from -15 degrees through to 60 degrees, at 15 degree increments. Additionally, five fluid velocities starting at 0.6 m/s through to 1.4 m/s, at 0.2 m/s increments were investigated. These results explain how the inversion of a 400 series block increases its hydrodynamic coefficients and subsequently decreases its stability performance in current flow. Ultimately, this study provides experimental information for the installation of 400 series articulated concrete mattresses in the inverted orientation.

2017 ◽  
Vol Vol 159 (A3) ◽  
Author(s):  
A Neville ◽  
R McLaren ◽  
J Weber ◽  
C Chin ◽  
J Binns ◽  
...  

An articulated concrete mattress model has been utilised to investigate the effects of reduced vertical centre of gravity on the stability of a 400 series block. Experimental testing was conducted at the AMC CWC, Beauty Point. To determine the effects that a reduced centre of gravity has on stability, the 3 by 3 articulated concrete mattress model was subject to pure uniform current flow. The subsequent forces were analysed with a six degree of freedom underwater force sensor. In order to gain a range of real world scenarios, the experimental model was tested at six flow angles ranging from -15 degrees through to 60 degrees, at 15 degree increments. Additionally, five fluid velocities starting at 0.6 m/s through to 1.4 m/s, at 0.2 m/s increments were investigated. These results explain how the inversion of a 400 series block increases its hydrodynamic coefficients and subsequently decreases its stability performance in current flow. Ultimately, this study provides experimental information for the installation of 400 series articulated concrete mattresses in the inverted orientation.


2009 ◽  
Vol 60 (3) ◽  
pp. 567-574 ◽  
Author(s):  
S. Beltrán ◽  
I. Irizar ◽  
H. Monclús ◽  
I. Rodríguez-Roda ◽  
E. Ayesa

The total amount of solids in Wastewater Treatment Plants (WWTPs) and their distribution among the different elements and lines play a crucial role in the stability, performance and operational costs of the process. However, an accurate prediction of the evolution of solids concentration in the different elements of a WWTP is not a straightforward task. This paper presents the design, development and validation of a generic Kalman observer for the on-line estimation of solids concentration in the tank reactors of WWTPs. The proposed observer is based on the fact that the information about the evolution of the total amount of solids in the plant can be supplied by the available on-line Suspended Solids (SS) analysers, while their distribution can be simultaneously estimated from the hydraulic pattern of the plant. The proposed observer has been applied to the on-line estimation of SS in the reactors of a pilot-scale Membrane Bio-Reactor (MBR). The results obtained have shown that the experimental information supplied by a sole on-line SS analyser located in the first reactor of the pilot plant, in combination with updated information about internal flow rates data, has been able to give a reasonable estimation of the evolution of the SS concentration in all the tanks.


In the first part of this paper opportunity has been taken to make some adjustments in certain general formulae of previous papers, the necessity for which appeared in discussions with other workers on this subject. The general results thus amended are then applied to a general discussion of the stability problem including the effect of the trailing wake which was deliberately excluded in the previous paper. The general conclusion is that to a first approximation the wake, as usually assumed, has little or no effect on the reality of the roots of the period equation, but that it may introduce instability of the oscillations, if the centre of gravity of the element is not sufficiently far forward. During the discussion contact is made with certain partial results recently obtained by von Karman and Sears, which are shown to be particular cases of the general formulae. An Appendix is also added containing certain results on the motion of a vortex behind a moving cylinder, which were obtained to justify certain of the assumptions underlying the trail theory.


2021 ◽  
Author(s):  
Saika Iwamatsu ◽  
Yasunori Nihei ◽  
Kazuhiro Iijima ◽  
Tomoki Ikoma ◽  
Tomoki Komori

Abstract In this study, a series of dedicated water tank tests were conducted in wind and waves to investigate the stability performance and turning motion of Floating Offshore Wind Turbine (FOWT) equipped with two vertical axis wind turbines (VAWT). The FOWT targeted in this study is called Multi-connection VAWT, which is a new type of FOWT moored by Single-Point-Mooring (SPM) system. We designed and manufactured two types of semi-submersible floating bodies. One is a type in which VAWTs are mounted in two places of a right-angled isosceles triangle (Type-A) on a single floater, and the other is two independent units equipped with VAWTs on two separate floaters centered on a moored body. This is a type in which two semi-submersible floating bodies are lined up in a straight line (Type-B). The experimental conditions were determined by scaling down to 1/100 using Froude’s scaling law based on a wind thrust load of 320 kN (rated wind speed of 12 m/s) assuming an actual machine. In the free yawing test in waves, Type-A turned downwards, while Type-B was barely affected by the waves. Furthermore, in the free yawing test in wind, both Type-A and Type-B turned leeward and stabilized at a final point where the wind load was balanced.


2018 ◽  
Vol 49 (2) ◽  
pp. 92-99 ◽  
Author(s):  
Stefano Melzi ◽  
Edoardo Sabbioni ◽  
Michele Vignati ◽  
Maurizio Cutini ◽  
Massimo Brambilla ◽  
...  

Fruit harvesting trucks are used to easy and speed-up the work of agricultural operators. These vehicles are provided with a moving cargo bed, which can be raised up to 3 meters from the ground so that workers are closer to the plants top. Due to factors like height of centre of gravity and operation on soft and irregular soil, these vehicles present several safety issues. This research, carried out inside a project funded by INAIL (Italian National Institute for Insurance against Accidents at Work), analysed the stability of fruit harvesting trucks with particular focus on rollover risk. Experimental tests were carried out to characterise the response of these vehicles. Multibody models of two trucks were then developed and used to determine the rollover angle along a generic direction considering the effect of vehicle configuration and of tire-soil stiffness.


Author(s):  
Swathi Kommamuri ◽  
P. Sureshbabu

Power system stability improvement by a coordinate Design ofThyristor Controlled Series Compensator (TCSC) controller is addressed in this paper.Particle Swarm Optimization (PSO) technique is employed for optimization of the parameterconstrained nonlinear optimization problem implemented in a simulation environment. The proposed controllers are tested on a weakly connected power system. The non-linear simulation results are presented. The eigenvalue analysis and simulation results show the effectiveness and robustness of proposed controllers to improve the stability performance of power system by efficient damping of low frequency oscillations under various disturbances.


2019 ◽  
Vol 13 (4) ◽  
pp. 289
Author(s):  
Didik Ariyanto ◽  
Suharyanto Suharyanto ◽  
Flandrianto Sih Palimirmo ◽  
Yogi Himawan

Ikan mas (Cyprinus carpio) merupakan komoditas budidaya yang mudah beradaptasi dengan berbagai kondisi lingkungan. Penelitian ini bertujuan mempelajari pengaruh genotipe, lingkungan, dan interaksi antara genotipe dengan lingkungan terhadap stabilitas penampilan fenotipik ikan mas dalam kegiatan budidaya. Rancangan percobaan menggunakan rancangan faktorial 3 x 5 dengan lima ulangan. Lima strain ikan mas, yaitu Rajadanu, Sutisna, Majalaya, Wildan, dan Sinyonya dipelihara secara komunal di dalam tiga model wadah budidaya, yaitu kolam beton, kolam jaring, dan kolam tanah, selama 90 hari. Hasil penelitian menunjukkan bahwa penampilan fenotipik ikan mas dipengaruhi oleh genotipe, lingkungan dan interaksi kedua faktor tersebut. Strain Sutisna dan Wildan mempunyai nilai sintasan yang paling baik di semua lingkungan dibanding tiga strain lainnya. Strain Sutisna mempunyai pertumbuhan terbaik di kolam tanah sedangkan strain Wildan di kolam jaring. Hal ini menyebabkan kedua strain tersebut menghasilkan biomassa panen terbaik pada lingkungan yang berbeda. Hasil analisis stabilitas menunjukkan bahwa kelima strain ikan mas dalam penelitian ini relatif tidak stabil dan mempunyai respons yang berbeda jika dipelihara pada lingkungan yang berbeda. Strain Wildan dan Rajadanu merupakan strain ikan mas yang mempunyai respons terhadap perbedaan lingkungan paling tinggi. Strain dengan karakteristik tersebut akan mempunyai performa terbaik pada lokasi dan kondisi pemeliharan yang sesuai dengan kebutuhannya, tetapi mempunyai penampilan fenotipik yang rendah jika kondisi lingkungan budidayanya tidak sesuai. Strain Sutisna, Sinyonya, dan Majalaya merupakan strain ikan mas dengan daya responsi terhadap lingkungan lebih rendah. Karakteristik ini menyebabkan penampilan fenotipik ketiga strain tersebut relatif stabil pada semua lokasi dan kondisi budidaya, meskipun tidak bisa mencapai hasil yang maksimal.Common carp (Cyprinus carpio) is known as fish species highly adaptable to various environmental conditions. This study aimed to evaluate the effect of genotype, environment, and their interaction in phenotypic performance stability of common carp. The experimental design used a 3 x 5 factorial design with five repetitions. Five strains of common carp, namely Rajadanu, Sutisna, Majalaya, Wildan, and Sinyonya were stocked communally for 90 days in three culture systems: concrete pond, net cage pond, and earthen pond. The result showed that the phenotypic performance of common carp was influenced by genotype, environment, and their interaction. Sutisna and Wildan strains have a higher survival rate compared to other strains in all culture systems. Sutisna and Wildan strains have the best growth performance in the earthen pond and net cage pond, respectively. Both strains also have the highest biomass production at harvest in all culture systems. Based on the stability performance analysis, Wildan and Rajadanu have the highest response to the different environmental conditions. Strains with this characteristic perform best in different locations or culture systems as long as the environmental conditions are suitable. However, these fish will likely perform poor in the unsuitable culture environment. Sutisna, Sinyonya, and Majalaya are carp strains with lower responsiveness to environmental change. Such characteristic causes the phenotypic performance of these three strains cannot achieve the maximum results, yet it is relatively stable in all locations.


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