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The development of energy recovery systems in vehicles is a form of synergy between energy efficiency and renewable energy to overcome the energy crisis and global warming problems. This paper addresses such challenges by introducing a novel design of a piezoelectric energy harvester (PEH) for a vehicle suspension system. The PEH is designed to capture the linear vibration of the suspension system subjected to road surface roughness and move on uniform bridges. The vibration is amplified by a pressurized liquid cylinder-piston mechanism which deforms the piezoelectric bar to produce electric power. An additional novel mechanism in the form of a piezoelectric protector is also proposed to avoid physical damage due to excessive unidirectional compressive force as a result of an unpredictable uneven road. Given the key design parameters, the electric power can be harvested up to 67.5 W for a PEH with a span of 150 m of the bridge, a velocity of 40 m/s, and a vehicle mass of 2,691.6 kg.

The development of energy recovery systems in vehicles is a form of synergy between energy efficiency and renewable energy to overcome the energy crisis and global warming problems. This paper addresses such challenges by introducing a novel design of a piezoelectric energy harvester (PEH) for a vehicle suspension system. The PEH is designed to capture the linear vibration of the suspension system subjected to road surface roughness and move on uniform bridges. The vibration is amplified by a pressurized liquid cylinder-piston mechanism which deforms the piezoelectric bar to produce electric power. An additional novel mechanism in the form of a piezoelectric protector is also proposed to avoid physical damage due to excessive unidirectional compressive force as a result of an unpredictable uneven road. Given the key design parameters, the electric power can be harvested up to 67.5 W for a PEH with a span of 150 m of the bridge, a velocity of 40 m/s, and a vehicle mass of 2,691.6 kg. [ABSTRACT FROM AUTHOR]

The 5.12 Wenchuan earthquake in 2008 led to a large number of loose deposits on the slope on both sides of the gully in the formation area. Under the triggering action of heavy rainfall, the previously unrecognized slope loose source in formation areas easily failed and started earlier than the overall start of the gully debris flow, which has practical significance for realizing the early warning of the gully debris flow starting. The special loose source conditions and postearthquake geological environment change the hydraulic mechanism of traditional debris flow start-up, which brings great difficulties to the monitoring and early warning of postearthquake debris flows. Therefore, based on hydraulics, on the premise of building a hydraulic model of groundwater level change of loose slope accumulation body, the characteristics and rules of groundwater level change are analyzed with the aid of hydraulic seepage theories, and the action characteristics of hydrodynamic pressure and hydrostatic pressure on the accumulation body are quantitatively studied. Based on field exploration data and average slope gradient, we divided the accumulation body in a reasonable manner; completed the sliding force, anti-sliding force and residual-sliding force mechanical expression and establishment; and performed a slope stability analysis. The research results show that the slope starting mode is divided into the thrust-type landslide and the retrogressive landslide mode of the subsection disintegration. The hydraulic deposit mechanism analytical results can also reverse the critical rainfall condition of slope failure. Finally, taking the Yindongzi gully in Dujiangyan as an example, the hydraulic mechanism of typical slope deposits in the formation area was analyzed and combined with the historical debris flow events in the study area to verify the physical simulation test, which was consistent with the field investigation results after the disaster. [ABSTRACT FROM AUTHOR]

Due to the perilous conditions in coal mine accidents, trapped people need to be rescued as soon as possible. The danger and complexity of this environment have brought great difficulties for search and rescue. The emergence of rescue robots has addressed this problem, and the improvement of their search-and-rescue ability is a key concern for rescue robot designers. Based on previous experience of a tracked mobile robot, this paper proposes a new solution via the addition of adjustive rocker arms. For this purpose, a hydraulic unit is installed between the rocker arms and the robot, which enables the rocker arms to be pulled back and forth, enabling its adaptation to more complex environments. In addition, based on kinematics equations, by analyzing the motion rules and characteristics of climbing typical obstacles including stairs, grooves, and lug steps, the present research not only works out the centroid coordinates but also explores the maximal obstacle height. The results show that when the rocker arms are extended by hydraulic pressure, the obstacle-climbing height of the robot increases 16.7 percent. This demonstrates the improvement in obstacle climbing ability and rescue efficiency in complex environments. [ABSTRACT FROM AUTHOR]

Due to the perilous conditions in coal mine accidents, trapped people need to be rescued as soon as possible. The danger and complexity of this environment have brought great difficulties for search and rescue. The emergence of rescue robots has addressed this problem, and the improvement of their search-and-rescue ability is a key concern for rescue robot designers. Based on previous experience of a tracked mobile robot, this paper proposes a new solution via the addition of adjustive rocker arms. For this purpose, a hydraulic unit is installed between the rocker arms and the robot, which enables the rocker arms to be pulled back and forth, enabling its adaptation to more complex environments. In addition, based on kinematics equations, by analyzing the motion rules and characteristics of climbing typical obstacles including stairs, grooves, and lug steps, the present research not only works out the centroid coordinates but also explores the maximal obstacle height. The results show that when the rocker arms are extended by hydraulic pressure, the obstacle-climbing height of the robot increases 16.7 percent. This demonstrates the improvement in obstacle climbing ability and rescue efficiency in complex environments.

Blow-out fractures are one of the most common fractures in maxillofacial trauma. Two mechanisms are thought to cause these fractures, the buckling mechanism and hydraulic mechanism. This study aims to compare between the two mechanisms in terms of intensity and extension using the finite elements method. Three-dimensional model was generated using computed tomography data of young male patient. Virtual loads were applied on the infra-orbital rim and the eyeball separately. Von Mises stress and equivalent elastic strain were examined in each simulation. The simulation predicted fractures on the infra-orbital rim and orbital floor when simulating the buckling mechanism, and on the orbital floor and mesial wall when simulating the hydraulic mechanism. Biomechanical studies are essential in understanding maxillofacial fractures mechanisms. Our results ascertained and confirmed what is seen clinically and explained the two mechanisms of blow-out fractures. [ABSTRACT FROM AUTHOR]

The diving beetles (Dytiscidae, Coleoptera) are families of water beetles. When they see light, they fly to the light source directly from the water. Their hind wings are thin and fragile under the protection of their elytra (forewings). When the beetle is at rest the hind wings are folded over the abdomen of the beetle and when in flight they unfold to provide the necessary aerodynamic forces. In this paper, the unfolding process of the hind wing of Cybister japonicus Sharp (order: Coleoptera) was investigated. The motion characteristics of the blood in the veins of the structure system show that the veins have microfluidic control over the hydraulic mechanism of the unfolding process. A model is established, and the hind wing extending process is simulated. The blood flow and pressure changes are discussed. The driving mechanism for hydraulic control of the folding and unfolding actions of beetle hind wings is put forward. This can assist the design of new deployable micro air vehicles and bioinspired deployable systems.

Failure of loose gully deposits under the effect of rainfall contributes to the potential risk of debris flow. In the past decades, researches on hydraulic mechanism and time-dependent characteristics of loose deposits failure are frequently reported, however adequate measures for reducing debris flow are not available practically. In this context, a time-dependent model was established to determine the changes of water table of loose deposits using hydraulic and topographic theories. In addition, the variation in water table with elapsed time was analyzed. The formulas for calculating hydrodynamic and hydrostatic pressures on each strip and block unit of deposit were proposed, and the slope stability and failure risk of the loose deposits were assessed based on the time-dependent hydraulic characteristics of established model. Finally, the failure mechanism of deposits based on infinite slope theory was illustrated, with an example, to calculate sliding force, anti-sliding force and residual sliding force applied to each slice. The results indicate that failure of gully deposits under the effect of rainfall is the result of continuously increasing hydraulic pressure and water table. The time-dependent characteristics of loose deposit failure are determined by the factors of hydraulic properties, drainage area of interest, rainfall pattern, rainfall duration and intensity.

A continuous variable valve lift (VVL) mechanism for a diesel engine is proposed in this research. The hydraulic mechanism, which consists of a driving plunger, a driven plunger, a hydraulic cylinder, and a hydraulic oil tank, is the key part of the VVL mechanism. Simulation is conducted to study the relationship between maximum valve lift and rotation angle of driving plunger. Calculation results indicate that the maximum valve lift decreases with increasing rotation angle. A prototype was manufactured and successfully tested in a single-cylinder diesel engine. The experiments, which were conducted at different rotation angles of the driving plunger, validate the accuracy of the calculation results. The difference between experimental valve lift curve and cam lift curve is considered the result of oil leakage. Rotating the driving plunger is an effective method to regulate valve lift. Working stability of the VVL mechanism is validated through a multi-cycle operation. Experimental results indicate that the VVL mechanism is effective and reliable for realizing continuous VVL in engines. [ABSTRACT FROM AUTHOR]

In most beetles, the hind wings are thin and fragile; when at rest, they are held over the back of the beetle. When the hind wing unfolds, it provides the necessary aerodynamic forces for flight. In this paper, we investigate the hydraulic mechanism of the unfolding process of the hind wings in Dorcus titanus platymelus (Oder: Coleoptera). The wing unfolding process of Dorcus titanus platymelus was examined using high speed camera sequences (400 frames/s), and the hydraulic pressure in the veins was measured with a biological pressure sensor and dynamic signal acquisition and analysis (DSA) during the expansion process. We found that the total time for the release of hydraulic pressure during wing folding is longer than the time required for unfolding. The pressure is proportional to the length of the wings and the body mass of the beetle. A retinal camera was used to investigate the fluid direction. We found that the peak pressures correspond to two main cross-folding joint expansions in the hind wing. These observations strongly suggest that blood pressure facilitates the extension of hind wings during unfolding. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study is to present a rational coherent hypothesis to explain the palpable involuntary movements of the cranium. The arterial and venous anatomy inside and around the skull and spinal column presents a complete vascular system with the capacity to regulate intra-cranial pressure to a level of equilibrium slightly higher than atmospheric pressure. Variations in cerebrospinal fluid (csf) pressure control the volume of blood draining through the cavernous sinus and hence into the inter-vertebral venous plexus in relation to the jugular vein. Stable intra-cranial pressure is maintained by a controlled release of venous blood through the inter-vertebral venous plexus (slow) and the jugular vein (fast) in the cavernous sinus. Any distortion of the skull from its healthy state will lead to reduced intra-cranial volume. The process of release from the state of compression has been interpreted as “cranial rhythm” but may be a mechanical adjustment increasing the internal volume of the skull, aided by the continual maintenance of stable intracranial pressure. This involuntary movement is capable of being assisted manually. [Copyright &y& Elsevier]

Introduction: Orbital wall fractures consider one of the most common fractures in the maxillofacial trauma. These fractures caused by two mechanisms, the buckling mechanism and hydraulic mechanism. This study aims to compare between the two mechanisms in terms of intensity and extension using the finite elements method., Material and Methods: Three-dimensional model of the skull was generated using computed tomography data of young male patient. Virtual loads were applied on the eyeball and the infra-orbital rim separately. Von Mises stresses were examined in each simulation., Results: The simulation predicted fractures on the infra-orbital rim and orbital floor when simulating the hydraulic mechanism, and on the orbital floor and mesial wall when simulating the buckling mechanism., Conclusion: Biomechanical studies are essential part in understanding maxillofacial fractures mechanisms. The results confirmed and ascertained what is seen clinically, and explained clearly the two mechanisms of orbital fractures., (Copyright © 2021 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

The diving beetles (Dytiscidae, Coleoptera) are families of water beetles. When they see light, they fly to the light source directly from the water. Their hind wings are thin and fragile under the protection of their elytra (forewings). When the beetle is at rest the hind wings are folded over the abdomen of the beetle and when in flight they unfold to provide the necessary aerodynamic forces. In this paper, the unfolding process of the hind wing of Cybister japonicus Sharp (order: Coleoptera) was investigated. The motion characteristics of the blood in the veins of the structure system show that the veins have microfluidic control over the hydraulic mechanism of the unfolding process. A model is established, and the hind wing extending process is simulated. The blood flow and pressure changes are discussed. The driving mechanism for hydraulic control of the folding and unfolding actions of beetle hind wings is put forward. This can assist the design of new deployable micro air vehicles and bioinspired deployable systems.

The paper presents the requirements imposed on suspension mechanism of tractors through which agricultural machines are coupled to tractors. Also, it is presented the functional principles of hydraulic action systems of suspension mechanism, such as: simple systems of lifting and descending, hydraulic systems with position adjustment, hydraulic systems with force adjustment. The hydraulic systems of simple lifting and descending can be equipped with a hydraulic cylinder with simple action or with double action. The hydraulic systems with position adjustment achieves the maintaining of the agricultural machine in a fix position towards the supporting plane of tractor. In the case of plowghing agregates, hydraulic systems with position adjustment assure the constant maintaining of the work depth when the grounds are better leveled up. The hydraulic systems with force adjustment achieve the modifying of machine position towards tractor depending on the resistance held by the agricultural machine (plow, for example) during work. The paper presents a theme of actuality, because in modem agriculture, in construction of tractors and agricultural machines, the hydraulic systems of actioning and adjustment got a considerable development. [ABSTRACT FROM AUTHOR]