In the current paper we present a method of rearing tench (Tinca tinca L.) larvae under controlled conditions, fed on dry food (Gemma and Perla) and Artemia nauplii or decapsulated cysts of Artemia. ...Tench larvae were obtained after artificial spawning by aid of Ovopel stimulation. Two experiments were conducted during which fish were divided into 4 groups (in duplicate) and placed in 30 dm
3
glass fish tanks set up in a recirculating system. The fish were fed ad libitum and reared for 25 days. Larvae were fed exclusively (experiment 1) or after 10 days (experiment 2) of receiving Artemia nauplii with two types of compound feeds and decapsulated cysts of Artemia. The best growth rate was observed in the control group fed on Artemia nauplii and in the group offered decapsulated cysts in both experiments. The highest survival rate, over 96%, occurred in the control group. A twofold worse survival rate was obtained in the group fed exclusively on dry food. Applied transition schedule had significant effect on survival rate among treatments, however it did not influence the percentage of body deformations occurring in groups receiving compound feed only. The results obtained indicate the necessity of applying gradual transition from live food to compound feed and the improvement of feeding schedules in common tench culture.
In the current paper we present a method of rearing tench (Tinca tinca L.) larvae under controlled conditions, fed on dry food (Gemma and Perla) and Artemia nauplii or decapsulated cysts of Artemia. ...Tench larvae were obtained after artificial spawning by aid of Ovopel stimulation. Two experiments were conducted during which fish were divided into 4 groups (in duplicate) and placed in 30 dm3 glass fish tanks set up in a recirculating system. The fish were fed ad libitum and reared for 25 days. Larvae were fed exclusively (experiment 1) or after 10 days (experiment 2) of receiving Artemia nauplii with two types of compound feeds and decapsulated cysts of Artemia. The best growth rate was observed in the control group fed on Artemia nauplii and in the group offered decapsulated cysts in both experiments. The highest survival rate, over 96%, occurred in the control group. A twofold worse survival rate was obtained in the group fed exclusively on dry food. Applied transition schedule had significant effect on survival rate among treatments, however it did not influence the percentage of body deformations occurring in groups receiving compound feed only. The results obtained indicate the necessity of applying gradual transition from live food to compound feed and the improvement of feeding schedules in common tench culture.
Given its orthotropic and hygroscopic nature, Chinese fir exhibits varying mechanical behaviors in earlywood and latewood due to its naturally inhomogeneous structure when exposed to changes in ...loading direction and given moisture content (MC) range from 7.9 % to 16.1 %. In this study, we combined micro-tensile testing and the digital image correlation (DIC) technique to derive the moisture -dependent orthotropic elastic constants, i.e., Young’s modulus (E), Poisson’s ratio (ν) and shear modulus (G) for both earlywood and latewood in Chinese fir. The findings revealed that when loading in the parallel direction, the restraining effect caused by latewood on earlywood resulted in a difference compared with loading in series. Interestingly, the loading direction impacted the restraining effect more significantly than MC. Additionally, both Young’s modulus and shear modulus exhibited decreases with increasing MC within above range for both earlywood and latewood. Notably, the Young’s modulus of earlywood showed a higher sensitivity to MC variations compared to latewood. However, Poisson’s ratio did not consistently correlate with MC within above range in all orthotropic directions. A three-dimensional coordinate system visualization of the compliance parameters highlighted the differing sensitivities of earlywood and latewood to moisture. The independent moisture-dependent elastic components of earlywood and latewood derived in this study extended the moisture-dependent mechanical model of wood, offering theoretical guidance for the practical application of Chinese fir and other wood species.
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•Combined micro-tensile and DIC technique to derive the moisture-dependent orthotropic elastic constants of Chinese fir.•Moisture-dependent elasticity of earlywood and latewood were compared.•The three-dimensional elastic behavior of earlywood or latewood was visualized by body deformation.
Bamboo, a biomaterial with a unique gradient structure, possesses exceptional mechanical properties. The gradient structure impacts the mechanical properties of bamboo in the longitudinal (L), radial ...(R) and tangential (T) directions. To investigate the elasticity associated with gradient structure, we derived the orthotropic elastic constants: Young’s modulus (E), Poisson’s ratio (ν) and shear modulus (G) at different radial positions (outer, central and inner) through micro-tensile testing and the digital image correlation (DIC) technique. Our results revealed that the Young’s modulus of bamboo exhibited a characteristic orthotropic behavior irrespective of radial position. The ratio of E in the L, T and R directions (EL:ET:ER) was 6.05:1.08:1, 5.12:1.17:1 and 8.02:1.58:1, respectively at the outer, central and inner positions. With increasing fiber fraction, ν (except νRT) demonstrated an upward trend. Under main axis tension, fiber pull-out and brittle fracture were the main failure modes, whereas off-axis tension exposed the vulnerable interface between fibers and parenchyma cells. The enhancement effect of the gradient structure in the L and T directions was more prominent, resulting in a consistent deformation pattern from the inner to outer positions. However, strain localization was found when tensioning through the R direction. Leveraging the derived orthotropic elastic constants, we visualized the three-dimensional elastic behavior of bamboo by body deformation. Bamboo at the outer position exhibited quasi-isotropic behavior in the RT plane due to the high fiber fraction. This study provides critical experimental evidence for the orthotropic behavior of bamboo at different radial positions and valuable data for mechanical modeling and practical applications involving bamboo.
•Orthotropic elasticity of gradient-structured bamboo was evaluated.•The effect of the gradient structure in the L and T directions was more prominent.•The three-dimensional elastic behavior of bamboo was visualized by body deformation.
VIPER Angles, Baptiste; Rebain, Daniel; Macklin, Miles ...
Proceedings of the ACM on computer graphics and interactive techniques,
07/2019, Letnik:
2, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We extend the formulation of position-based rods to include elastic volumetric deformations. We achieve this by introducing an additional degree of freedom per vertex -- isotropic scale (and its ...velocity). Including scale enriches the space of possible deformations, allowing the simulation of volumetric effects, such as a reduction in cross-sectional area when a rod is stretched. We rigorously derive the continuous formulation of its elastic energy potentials, and hence its associated position-based dynamics (PBD) updates to realize this model, enabling the simulation of up to 26000 DOFs at 140 Hz in our GPU implementation. We further show how rods can provide a compact alternative to tetrahedral meshes for the representation of complex muscle deformations, as well as providing a convenient representation for collision detection. This is achieved by modeling a muscle as a bundle of rods, for which we also introduce a technique to automatically convert a muscle surface mesh into a rods-bundle. Finally, we show how rods and/or bundles can be skinned to a surface mesh to drive its deformation, resulting in an alternative to cages for real-time volumetric deformation. The source code of our physics engine will be openly available1.
There are several external and internal abnormalities that affect development in both wild and farmed fish. One of these abnormalities is known as saddleback syndrome (SBS), characterized by ...abnormalities in the shape, number, or absence of dorsal pterygiophores, causing a concavity in the dorsal region and absence of fin sections. The causes of this syndrome are not yet clear, but could be caused by fishing or predator damage, nutritional deficiencies, genetic conditions and environmental stress from pollutants that may cause alteration in the ontogenetic development of the fish. This study recorded for the first time the SBS in a wild-caught specimen of Thorichthys meeki Brind, 1918 (Cichlidae). Specimens were collected in the locality of Chekubul, municipality of Carmen, Campeche, México on November 18, 2022. The development of the dorsal fin begins from the first to the ninth dorsal spine where there is a dorsal concavity, which ends with the last three dorsal spines. There is no evidence of scoliosis or lordosis from the X-ray analysis; however, the dorsal pterygiophores show irregularities in their development. The specimen with the syndrome showed no other body abnormalities that would have prevented its development to adulthood, although the causative agent is unclear.
•A phase separation method based on Gaussian 1σ-criterion is proposed to isolate local-body phase from whole phase.•Position and shape of the superficial and subsurface defects in Culture Heritage ...have been detected by NDA-DH system.•Fundamental human voice is considered, results show local-body deformation is less sensitive to acoustic frequencies.
Previous collaborative studies have shown that fringe patterns by optical interference way are used as a direct diagnostic tool for qualitative analysis of defects in Culture Heritage. Nevertheless, the complexity of the fringe patterns prevents the accurate quantification of defects. In this study, a phase separation method based on the weighted least-squares algorithm is proposed to conveniently isolate the local phase distribution from the whole, complex fringe pattern. This method is examined to accurately quantify the deformation and strain distribution of visible and invisible defects. In experimental work, the Non-destructive Acoustic excitation and Digital Holography (NDA-DH) detection is employed for the superficial and subsurface defects in the Ruting murals of the Forbidden City, Beijing. Under the impact of fundamental human voice, the frequency range of the acoustic excitation was considered from 100–800 Hz. All results show that the suggested phase separation method allows direct observation of defects as well as quantified surface deformation providing a precious documentation to the conservators.
Flippers are key tissues through which frogs swim in water, and their spreading and contracting state directly affects their ability to move while driving their hind limbs. First, inspired by ...movement mechanism of frog flippers, a controllable soft-body extension-driven frog-like flipper mechanism was designed by combining the large elasticity and strong ductility of soft-body materials. This mechanism is driven by single motor via linkage gear, enabling it to simulate the changing state of flipper extension precisely controlled by the frog as it swims. Second, nonlinear mechanical calculations of flipper deformation membrane were carried out, and deformation optimization model based on Ogden's super soft-body material was established. Subsequently, integral analysis of the deformed area of flippers was used to obtain a fluid dynamics model of the paddling performance. Theoretical calculations and computational fluid dynamics simulations have shown that flippers can instantaneously control changes in the flipper area to inhibit fluid separation while swimming, effectively reducing the water drag of flippers in water and thus increasing the swimming propulsive force. Finally, when the spreading area of flippers was the same, and the swimming efficiency increased by 1, 1.6, and 1.9 times compared with that of fixed, passive folding, and passive spring flippers, respectively.
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