scholarly journals Avian mud nest architecture by self-secreted saliva

2021 ◽  
Vol 118 (3) ◽  
pp. e2018509118
Author(s):  
Yeonsu Jung ◽  
Sohyun Jung ◽  
Sang-im Lee ◽  
Wonjung Kim ◽  
Ho-Young Kim
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Bird Species ◽  
Experimental Measurements ◽  
Nest Construction ◽  
Nest Architecture ◽  
Artificial Nests ◽  
Granular Piles ◽  
Biopolymer Solutions ◽  
Sufficient Strength

Mud nests built by swallows (Hirundinidae) and phoebes (Sayornis) are stable granular piles attached to cliffs, walls, or ceilings. Although these birds have been observed to mix saliva with incohesive mud granules, how such biopolymer solutions provide the nest with sufficient strength to support the weight of the residents as well as its own remains elusive. Here, we elucidate the mechanism of strong granular cohesion by the viscoelastic paste of bird saliva through a combination of theoretical analysis and experimental measurements in both natural and artificial nests. Our mathematical model considering the mechanics of mud nest construction allows us to explain the biological observation that all mud-nesting bird species should be lightweight.

Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality

2013 ◽  
Vol 760-762 ◽  
pp. 2263-2266
Author(s):  
Kang Yong ◽  
Wei Chen
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Yield Strength ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Significant Influence ◽  
External Pressure ◽  
Pipe Diameter ◽  
Axial Loads ◽  
The Stability

Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

scholarly journals Endemic Cyprus Scops Owl Otus cyprius Readily Breeds in Artificial Nest Boxes

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1775
Author(s):  
Savvas Iezekiel ◽  
Reuven Yosef ◽  
Constantinos Themistokleus ◽  
Dimitrios E. Bakaloudis ◽  
Christos G. Vlachos ◽  
...  
Keyword(s):  
Rural Areas ◽  
Habitat Preferences ◽  
Bird Species ◽  
Laying Date ◽  
Artificial Nests ◽  
Breeding Parameters ◽  
Island Endemic ◽  
Nest Boxes ◽  
Ecological Requirements ◽  
Old Trees

As is well-known, endemic island bird species are especially vulnerable to extinction from anthropogenic environmental change and reduced fitness compared with mainland taxa. The Cyprus Scops Owl, Otus cyprius, is a recently recognized island endemic species whose ecology and breeding biology have not been studied. It nests mainly in holes in trees and buildings, so the felling of old trees, modern architectural practices, and the renovation of old houses in villages may reduce nest site availability. Its population trend is also unknown. Therefore, to better determine its ecological requirements and habitat preferences we placed nest boxes in rural areas adjacent to the forest, in the forest, and in the ecotone between them, and used breeding success as our indicator of habitat suitability. We found that breeding parameters like laying date, clutch size, length of the incubation period, hatching day, hatching success, and number of nestlings did not differ between the three habitats. Despite the low level of nest box occupancy rate (5–11%) the endemic Cyprus Scops Owl readily breeds in artificial nests. Therefore, although we are unaware of any current threats to the Cyprus Scops Owl, we recommend that its conservation be prioritized, including studies, monitoring, habitat conservation, and the provision of nest boxes.

Attenuation of pulsations in the reciprocating compressor piping system with an elbow-shaped surge tank

2018 ◽  
Vol 233 (5) ◽  
pp. 1677-1689
Author(s):  
Quyang Ma ◽  
Guoan Yang ◽  
Mengjun Li
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Frequency Analysis ◽  
Transfer Matrix Method ◽  
Piping System ◽  
Pulsation Frequency ◽  
Reciprocating Compressor ◽  
Pressure Pulsations ◽  
Surge Tank ◽  
The Mathematical Model

An elbow-shaped surge tank is proposed to suppress the pressure pulsations. The transfer matrix method was developed and the mathematical model was established to predict the distribution of pressure pulsations in the piping system (on which a surge tank was already installed) with an elbow-shaped surge tank. Simulation work of the whole piping system was performed. The results show that the elbow-shaped surge tank has good performance to attenuate the pressure pulsations. The frequency analysis shows that the amplitude for the first pulsation frequency is attenuated to a low level. The impulse response was analyzed to examine the efficiency of suppressing pulsations by using the suppressor. The theoretical analysis showed that there exists the optimal suppression performance when setting the distance between the elbow-shaped surge tank and the existing one. Meanwhile, modifying the ratio of length to diameter with a fixed surge volume could also impact the pressure pulsations. The analysis results can be used as a reference in designing and installing the elbow-shaped surge tank.

scholarly journals DETERMINING THE FORCES OF INTERACTION OF MAIN GEOKHODS SYSTEMS WITH GEO-ENVIRONMENT AND WITH EACH OTHER

2018 ◽  
pp. 23-30
Author(s):  
V. Yu. Beglyakov ◽  
V. V. Aksenov ◽  
I. K. Kostinets ◽  
A. A. Khoreshok
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Interaction Process ◽  
Generalized Model ◽  
Machine Elements ◽  
General Mathematical Model ◽  
Mine Workings ◽  
Modular Principles ◽  
Sufficient Strength

The processes occurring during the geodetic excavation of underground excavations are characterized by the interaction of the elements of the geokhod with each other and with the geo-environment. The interaction process can be investigated in mathematical modeling, solving the problems of justifying the parameters of the drives and interacting forces, ensuring sufficient strength of the machine elements and the bearing capacity of the contour array. The proposed block-modular principles of constructing a mathematical model allow solving particular problems of the system and its individual elements. From the solution of particular problems, it is now necessary to proceed to the solution of the generalized model, using equivalent loads and reduced total moments (forces). The construction of a generalized model requires a number of assumptions, but its solution will reveal the interaction between the elements of the geokhod and the geo-environment, which is very relevant.As an example, the solution of a particular problem is given-the determination of the value of the forces arising from the interaction of the blade of an external engine with the medium.A list of assumptions is formulated that allow us to describe a general mathematical model of the interaction between the geo-environment and the geokhod, as well as the processes occurring during geodetic excavation of mine workings.

Thickness Deformation of Constrained Layer Damping: An Experimental and Theoretical Evaluation

2000 ◽  
Vol 123 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Peter Y. H. Huang ◽  
Per G. Reinhall ◽  
I. Y. Shen ◽  
Jessica M. Yellin
Keyword(s):  
Mathematical Model ◽  
Transfer Functions ◽  
Viscoelastic Layer ◽  
Experimental Setup ◽  
Experimental Measurements ◽  
Constrained Layer Damping ◽  
Response Functions ◽  
Theoretical Evaluation ◽  
Calculated Frequency ◽  
Direct Measurements

This paper presents a study of thickness deformation of the viscoelastic material in constrained layer damping (CLD) treatments. The first goal of the study is to demonstrate the feasibility of using direct measurement to investigate thickness deformation in CLD treatments. The experimental setup consisted of a constrained layer beam cantilevered to a shaker, an accelerometer mounted at the cantilevered end, and two laser vibrometers that simultaneously measured the responses of the base beam and the constraining layer, respectively, at the free end. A spectrum analyzer calculated frequency response functions (FRFs) between the accelerometer inputs and the vibrometer outputs. Measured FRFs of the base beam and the constraining layer were compared to detect thickness deformation. Experimental results showed that direct measurements can detect thickness deformation as low as 0.5 percent. The second goal is to evaluate the accuracy of a mathematical model developed by Miles and Reinhall [7] that accounts for thickness deformation. FRFs were calculated by using the method of distributed transfer functions by Yang and Tan [13]. Comparison of the numerical results with the experimental measurements indicated that consideration of thickness deformation can improve the accuracy of existing constrained layer damping models when the viscoelastic layer is thick.

scholarly journals Is it safe to nest near bold neighbours? Spatial patterns in predation risk associated with the density of American Golden-Plover nest

2016 ◽  
Author(s):  
Marie-Andrée Giroux ◽  
Myriam Trottier-Paquet ◽  
Joël Bêty ◽  
Vincent Lamarre ◽  
Nicolas Lecomte
Keyword(s):  
Predation Risk ◽  
Spatial Patterns ◽  
Bird Species ◽  
Artificial Nests ◽  
Species Of Conservation Concern ◽  
Composition And Structure ◽  
Negative Effect ◽  
Conservation Concern ◽  
Golden Plover ◽  
Mobbing Behaviour

Predation is one of the main factors explaining nesting mortality in most bird species. Birds can avoid nest predation or reduce predation pressure by breeding at higher latitude, showing anti-predator behaviour, and nesting in association with protective species. Plovers actively defend their territory by displaying early warning and aggressive/mobbing behaviour, potentially benefiting the neighbouring nests by decreasing their predation risk. To test for the existence of such a protective effect, we studied the influence of proximity to plover nests on predation risk of artificial nests on Igloolik Island (Nunavut, Canada) in July 2014. We predicted that the predation risk of artificial nests increases and decreases with the distance to and the density of plover nests, respectively. We monitored 18 plover nests and set 35 artificial nests at 30, 50, 100, 200 and 500 m from seven of those plover nests. Surprisingly, we showed that predation risk of artificial nests increases with the density of active plover nests. We also found a significant negative effect of the distance to the nearest active protector nest on predation risk of artificial nests. Understanding how the composition and structure of shorebird communities generate spatial patterns in predation risks represent a key step to better understand the importance of these species of conservation concern in tundra food webs.

scholarly journals Theoretical Analysis and Adaptive Synchronization of a 4D Hyperchaotic Oscillator

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
T. Fonzin Fozin ◽  
J. Kengne ◽  
F. B. Pelap
Keyword(s):  
Mathematical Model ◽  
Adaptive Control ◽  
Theoretical Analysis ◽  
Electronic Circuit ◽  
Adaptive Synchronization ◽  
Uncertain Parameters ◽  
Exponential Nonlinearity ◽  
Dynamical Properties ◽  
Hyperchaotic Systems ◽  
Good Agreement

We propose a new mathematical model of the TNC oscillator and study its impact on the dynamical properties of the oscillator subjected to an exponential nonlinearity. We establish the existence of hyperchaotic behavior in the system through theoretical analysis and by exploiting electronic circuit experiments. The obtained numerical results are found to be in good agreement with experimental observations. Moreover, the new technique on adaptive control theory is used on our model and it is rigorously proven that the adaptive synchronization can be achieved for hyperchaotic systems with uncertain parameters.

scholarly journals A bistable structural element

2008 ◽  
Vol 222 (11) ◽  
pp. 2045-2051 ◽  
Author(s):  
T Schioler ◽  
S Pellegrino
Keyword(s):  
Theoretical Analysis ◽  
Analytical Model ◽  
Mechanical Behaviour ◽  
The Other ◽  
Experimental Measurements ◽  
Structural Element ◽  
High Stiffness ◽  
Revolute Joints ◽  
Prototype Structure ◽  
Good Agreement

This article presents a novel bistable structural element that has high stiffness in stable configurations, but requires only a small amount of energy to be switched from one configuration to the other. The element is based on a planar linkage of four bars connected by revolute joints, braced by tape-spring diagonals. A description of the concept is presented, along with a detailed theoretical analysis of its mechanical behaviour. Experimental measurements obtained from a prototype structure are found to be in very good agreement with the predictions from this analytical model.

Motion Control of an Electromechanical Micro Robot

2020 ◽  
Vol 63 (6) ◽  
pp. 57-65
Author(s):  
Ruzil Safiullin ◽  
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Motion Control ◽  
Elastic Element ◽  
Human Life ◽  
Robotic Systems ◽  
System Of Equations ◽  
Functional Modules ◽  
Innovative Technologies ◽  
Micro Robot

Currently, the development of innovative technologies in the field of electromechanics are microelectrome-chanical systems. They are widely used both in various industries and in domestic conditions of human life. An algorithm and a mathematical model of the design of an electromechanical composite microrobot have been developed. A system of equations of mechanics and electrodynamics was used to describe its metrological char-acteristics. By solving this system of equations, a theoretical analysis of the operation of its engine with a spiral secondary elastic element is carried out. Using the mechatronic approach, the buoyancy and coordination of its functional modules are studied. The results of this article will be useful for engineers involved in the design and operation of micro robots using robotic systems in the fields of biotechnology and biomechanics.

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