Source Of Mechanical Energy Research Articles

Protein Folding Drives Muscle Contraction

In the current view of muscle contraction, the power stroke of a myosin motor is the sole source of mechanical energy driving the contraction of muscle. These models exclude titin, the largest protein in the human body, which sets the passive elasticity of muscles. Here, we show that stepwise unfolding/folding of titin Ig domains occurs in the elastic I band region of intact myofibrils and that the physiological forces on titin fall between 6-8 pN. We utilize magnetic tweezers together with HaloTag anchoring to record the extension of titin Ig domains I10 and I91 for several hours at nanometer resolution in passive force-clamp mode. Titin Ig domains that had been previously unfolded undergo spontaneous stepwise folding at forces below 10 pN. We show that under a pulling force of 8 pN, previously unfolded I10 or I91 domains undergo a stepwise contraction of 13 nm, as they move from the collapsed to the molten globule state. Thus, folding of a single Ig domain at the physiological force of 8 pN, generates 105 zJ of contractile energy, which is larger than the mechanical energy delivered by the power stroke of a single myosin motor (∼40 zJ). From published measurements of passive muscle elasticity, we calculate that both “soft” and “stiff” muscles operate over a range of forces that straddle the folding probability of Ig domains as shown here. We propose that the stretching of an inactivated muscle recruits Ig domains to the unfolded state; activation of the myosin motors reduces the force on titin to harness the energy of Ig domain folding. From this perspective, both the myosin motors and titin operate as an inextricable molecular system for the storage and delivery of mechanical energy.

Work Done by Titin Protein Folding Assists Muscle Contraction.

Current theories of muscle contraction propose that the power stroke of a myosin motor is the sole source of mechanical energy driving the sliding filaments of a contracting muscle. These models exclude titin, the largest protein in the human body, which determines the passive elasticity of muscles. Here, we show that stepwise unfolding/folding of titin immunoglobulin (Ig) domains occurs in the elastic I band region of intact myofibrils at physiological sarcomere lengths and forces of 6-8 pN. We use single-molecule techniques to demonstrate that unfolded titin Ig domains undergo a spontaneous stepwise folding contraction at forces below 10 pN, delivering up to 105 zJ of additional contractile energy, which is larger than the mechanical energy delivered by the power stroke of a myosin motor. Thus, it appears inescapable that folding of titin Ig domains is an important, but as yet unrecognized, contributor to the force generated by a contracting muscle.

Empirical closures for particulate debris bed spreading induced by gas–liquid flow

Efficient removal of decay heat from the nuclear reactor core debris is paramount for termination of severe accident progression. One of the strategies is based on melt fragmentation, quenching and cooling in a deep pool of water under the reactor vessel. Geometrical configuration of the debris bed is among the important factors which determine possibility of removing the decay heat from the debris bed by natural circulation of the coolant. For instance, a tall mound-shape debris bed can be non-coolable, while the same debris can be coolable if spread uniformly. Decay heat generates a significant amount of thermal energy which goes to production of steam inside the debris bed. Two-phase flow escaping through the top layer of the bed becomes a source of mechanical energy which can move the particulate debris along the slope of the bed. The motion of the debris will lead to flattening of the bed. Such process is often called “self-leveling” phenomenon. Spreading of the debris bed by the self-leveling process can take significant time, depending on the initial debris bed configuration and other parameters. There is a competition between the time scales for reaching (i) a coolable configuration of the bed, and (ii) onset of dryout and re-melting of the debris. In the previous work we have demonstrated that the rate of particulate debris spreading is determined by local gas velocity and local slope angle of the bed. In this work we develop a scaling approach and a closure for prediction of debris spreading rate based on generalization of available experimental data. We demonstrate that introduced scaling criteria are universal for particles of different shapes and size distributions.

Reclaiming the Don: An Environmental History of Toronto's Don River Valley, by Jennifer L. Bonnell

Reclaiming the Don: An Environmental History of Toronto's Don River Valley, by Jennifer L. Bonnell. Toronto, University of Toronto Press, 2014. xxx, 277 pp. $65.00 Cdn (cloth), $29.95 Cdn (paper). Jennifer Bonnell's Reclaiming the Don is a captivating history of a tiny river valley's intimate connection to the development of Toronto from the 1790s to the present. Organized around successive visions and plans for the Don, as well as the natural, political, and social forces that influenced them, the book explores the interplay of these different imagined futures as a dynamic process of historical change with profound consequences for the watershed and city. Bonnell's study reveals a key historical pattern. For elites, the river shifted from a central feature of a colonial town to a marginalized and disease-ridden industrial sewer and then to a celebrated corridor of metropolitan development and parkland. These pendulum swings between a landscape of opportunity and a waste space reveal the complexity of our material and cultural relationships with rivers over time and help to explain the intricately layered history of Canada's largest urban landscape and one of its most polluted waterways. Moreover, Bonnell's skillful investigation of how the Don has been many things to many people offers insight into the changing nature of urban pollution and shifting environmental values across two centuries. The book's first two chapters discuss the river as an Aboriginal portage route, a source of fertile soils, clay, and mechanical energy for settlers, as well as a waste sink and railbed for a rapidly industrializing city. Chapter three examines the Don Improvement Project, a large scale attempt to re-engineer the river with the competing goals of riverine flood control, harbour transportation, human health, and the expansion of urban space. Bonnell's fourth chapter explores the transient cultures and liminal spaces that emerged around the river in the late nineteenth and early twentieth century. The remaining three chapters focus on conservationist Charles Sauriol's efforts to preserve the Don and the theatrical protests of a burgeoning Canadian environmental movement; the development of a metropolitan parkway through the river valley; and the city's latest plan to redesign the Don's mouth. Throughout the book, Bonnell demonstrates her skill as a gifted storyteller by combining case studies of key events, social groups, and modernization projects, with biography and landscape analysis, in an engaging and cohesive narrative. Moreover, the maps, engineering plans, and photographs accompanying the text help readers visualize the Don's history and geography. The links Bonnell forges between marginal environments and social outcasts are an invaluable contribution to Canadian history. …

Enhanced energy harvesting based on surface morphology engineering of P(VDF-TrFE) film

Polyvinylidene fluoride (PVDF) has great potential for its use as an energy harvesting material as it exhibits not only outstanding piezoelectric and electrostatic characteristics resulting from ferroelectric effects, but also remarkably robust stability against repeated mechanical stress compared to inorganic materials. We report enhanced performances of poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) based energy generators with wider range of selections of flexible substrates through a surface morphology engineering using solvent annealing method as the key technology for simple and cost-effective fabrication at room temperature. It is clearly revealed that a solvent annealed P(VDF-TrFE) film is crystallised at room temperature and that the surface morphology is changed from a rough surface into a smooth and flat surface with increasing annealing time. This surface morphology engineering results in 8 times enhanced output voltage and current of the energy generators because of well-aligned electrical dipoles. We also demonstrate a highly transparent and flexible energy generator by employing graphene electrodes with the solvent annealed P(VDF-TrFE) film, which can be effectively harvesting various mechanical energy sources.

Nanopatterned Fiber Based Textile Triboelectiric Nanogenerator

There has been increasing demand for highly efficient portable energy harvesters due to the development and mass consumption of portable electronic devices. Photovoltaic, thermoelectric, piezoelectric and triboelectric energy scavengers have become strong candidates for portable energy harvesters in future self-powered portable electronic device applications.Among these, Triboelectric energy harvesters that can convert mechanical energy into electrical energy have recently attracted attention. Compared to time-constrained photovoltaic, piezoelectric energy harvesters are not limited in time and space because mechanical energy sources such as body movement, heartbeat, blood flow, wind, tide, low-frequency seismic vibrations, and sound from the surrounding environment are prevalent. In this study, we report the textile based as a substrate for foldable and wearable triboelectric power generators. Nano-size pattened PDMS on the conductive woven fabric substrate by dip-coated method. For practical applications, nano patterned conductive woven fabric based power generator showed the continuous driving of the liquid crystal display screen and light emitting diode successfully. Furthermore, textile based power generator showed high sensitivity acts low applying for of under 1kgf. The results presented here may create new possibilities for energy harvesting wearable devices, particularly in applications that require wearability and flexibility.

Laboratory-Scale-Model Testing of Well Stimulation by Use of Mechanical-Impulse Hydraulic Fracturing

Summary Reservoir stimulation is commonly used to increase well-production rates and enable economic oil and gas recovery from conventional and unconventional reservoirs. One potential stimulation method that has been laboratory tested as a means to increase well injectivity after conventional hydraulic fracturing is mechanical-impulse hydraulic fracturing (MIHF). MIHF is a high-strain-rate stimulation method that uses a mechanical-energy source as an alternative to rapid gas expansion. Field-scale viability of MIHF was evaluated by use of elastic mechanics and thermodynamics. Results from laboratory tests are presented in which associated flow data indicated significant increases to well injectivity after MIHF stimulation. Tests were performed in two granite specimens with dimensions of 300×300×240 mm3 and 300×300×300 mm3, respectively. The first specimen was unconfined at room-temperature conditions, whereas the second was subjected to heating and true-triaxial confinement. Stimulated well injectivity was evaluated with a series of step-constant-pressure and step-constant-flow injection tests.

Hydraulic efficiency of horizontal waterwheels: Laboratory data and CFD study for upgrading a western Himalayan watermill

Traditional waterwheels are widely used in remote areas as a source of mechanical energy for grinding grain. The classical design suffers of a very low hydraulic efficiency. The basic challenge is to increase the power output but not the rpms, with a desirable working regime in the range of 120–160 rpm. We study the hydraulic efficiency of waterwheels with analytical expressions and measured data from two laboratory scale designs in a variety of cases that differ in 1) blade inclination angle, 2) inclination angle of the water conduit, 3) blade geometry and 4) impact point of the waterjet on the blade surface. A waterwheel with blades with a notch in the upper edge does not improve the straight blade results. A very simple curved blade profile may enhance the hydraulic efficiency up to 46%. We analyze the performance of the new designs when applied to a real waterwheel located in the western Himalaya by means of Computational Fluid Dynamics (CFD) simulations. The maximum power delivered by the traditional wooden made waterwheel is 1.97 kW at 120 rpm. The waterwheel having 36 curved iron blades generates a power equal to 3.2 kW also at 120 rpm.

A vibration-driven nanogenerator fabricated on common paper substrate for harvesting energy from environment

There are numerous sources of mechanical energy in our environment, such as ultrasonic waves, body movement, and irregular air flow/vibration. Here, we present a simple, cost-effective approach for fabricating a flexible nanogenerator and apply it to harvest energy from environmental mechanical vibrations. The nanogenerator was based on ZnO nanorods grown on common paper substrate using a low-temperature hydrothermal method. Piezoelectric currents were measured by attaching the nanogenerator on the surface of a cantilever and a wind-up drum, respectively. At the same time, the vibrations of the cantilever and wind-up drum could also be characterized by the corresponding output signals. This is a practical and versatile technology with the potential for converting a variety of environment energy into electric energy, and also with the application for pre-warning of emergency, such as earthquake and burgling.

A flexible anisotropic self-powered piezoelectric direction sensor based on double sided ZnO nanowires configuration

We have successfully synthesized highly dense and well aligned zinc oxide nanowires (NWs) on the two sides of a PEDOT: PSS substrate by a single step low temperature hydrothermal method. The grown sample was used to fabricate a double sided piezoelectric nanogenerator (NG). The maximum harvested output power density from the fabricated double sided NG configuration was about 4.44 mW cm−2. The results obtained from the present double sided NG were approximately double the output from a single side. In addition to that, the voltage polarity of the harvested voltage from the two sides of the NG has been investigated. The results showed that upon bending, an anisotropic voltage polarity is generated on the two sides. Indicating that, this double sided NG can be used as a self-powered voltage polarity based direction sensor. The results of the present flexible double sided NG is very promising for harvesting energy from irregular mechanical energy sources in the surrounding environment. In addition, the fabricated configuration showed stability for sensing and can be used in surveillance and security applications.

Robust triboelectric nanogenerator based on rolling electrification and electrostatic induction at an instantaneous energy conversion efficiency of ∼ 55%.

In comparison to in-pane sliding friction, rolling friction not only is likely to consume less mechanical energy but also presents high robustness with minimized wearing of materials. In this work, we introduce a highly efficient approach for harvesting mechanical energy based on rolling electrification and electrostatic induction, aiming at improving the energy conversion efficiency and device durability. The rolling triboelectric nanogenerator is composed of multiple steel rods sandwiched by two fluorinated ethylene propylene (FEP) thin films. The rolling motion of the steel rods between the FEP thin films introduces triboelectric charges on both surfaces and leads to the change of potential difference between each pair of electrodes on back of the FEP layer, which drives the electrons to flow in the external load. As power generators, each pair of output terminals works independently and delivers an open-circuit voltage of 425 V, and a short-circuit current density of 5 mA/m(2). The two output terminals can also be integrated to achieve an overall power density of up to 1.6 W/m(2). The impacts of variable structural factors were investigated for optimization of the output performance, and other prototypes based on rolling balls were developed to accommodate different types of mechanical energy sources. Owing to the low frictional coefficient of the rolling motion, an instantaneous energy conversion efficiency of up to 55% was demonstrated and the high durability of the device was confirmed. This work presents a substantial advancement of the triboelectric nanogenerators toward large-scope energy harvesting and self-powered systems.

Linear Serial Elastic Hydraulic Actuator: Digital Prototyping and Force Control

In aggressive environments for humans, such as those present in the offshore industry, the main alternative is to replace human labor by remotely controlled robots, and some cases completely autonomous robots. The environment affects directly on robots tasks. When a robot works in a structured environment, its automation is easier since the environment can be modeled by dynamics equations. However if the environment is non-structured this modeling is quite difficult and presents a high computational effort. To overcome this difficult, over the years series elastic actuator (SEA) has been applied in non-structured environments. Actuators of the mechanical systems are always rigidly connected to the load to be moved. This can be observed in the hydraulic systems of agricultural, highway construction and mining equipment and in elevation and cargo transportation, among others. Unlike rigid actuators, a SEA contains an elastic element in series with the mechanical energy source. Such an elastic element gives SEA's several unique properties compared to rigid actuators, including tolerance to impact loads, low mechanical output impedance, passive mechanical energy storage, and increased peak power output. However it is not trivial to select the correct spring for the system. The spring has to be able to support the loads, but the spring cannot be too stiff, otherwise system impedance will be high. Iterative methods are needed to select the spring, which fits in impedance and bandwidth parameters. The resonance frequency is another issue for SEAs. This paper describes an entire digital prototyping of a linear serial elastic hydraulic actuator. It is done a digital prototyping of a tubular actuator design, which encapsulates the mechanical and electrical components and sensors. The digital prototype dimensions, mass and inertia properties are used to build the dynamic model for simulations and implementation of a controller. Moreover the methodology adopted results in a good response actuator with a compact and high force design

Effect of Architectural Glazing Parameters, Shading, Thermal Mass and Night Ventilation on Public Building Energy Consumption under Hungarian Climate

An important field of improving energy eciency of public and oce buildings with glazed facades is a conscious design of the building skin. The study first sets categories of available (conventional and sophisticated) glazing product types used in exterior walls on the basis of thermal transmission, solar heat gain and light transmission properties. A large number of computer simulations has been run using different glazing types, fenestration rates, fixed and moveable (controlled) external shadings, night ventilation rates and internal heat storage capacity in order to determine their effect on energy demands. The study compares heating, cooling and lighting energy demands of the internal spaces, independently from choice of mechanical systems and energy sources in order to analyse the clear effect of building skin and related parameters on energy needs. The simulation were run for Hungarian location (Szombathely), however the results and findings can be adopted for regions of similar continental climate. The target of the study is to set guidelines for the early stages of architectural design of energy efficient glazed façade constructions and buildings.

Integral activity of intrapulmonary source of mechanical energy in healthy subjects and in patients with obstructive lung diseases

Two functional levels of mechanical energy intrapulmonary source have been viewed in this article for the first time. The first level is located into the perialveolar space. This level provides inspiratory and expiratory activity of the lungs together with respiratory muscles. Due to this, the inspiratory alveolar pressure is lower than the intrapleural pressure and the expiratory alveolar pressure is higher than the intrapleural pressure. This is deter mined by work of breathing measured as negative elastic hysteresis area and allows overcoming some nonelastic resistance of the lungs. The lung activity on overcoming the elastic resistance is estimated by multiplying the total work of breathing by a functional coefficient of lung elasticity (FCLE). The latter is calculated by dividing the total lung compliance by the dynamic lung compliance and reflects change in the elastic lung tension from spontaneous breathing level to the total lung compliance level. FCLE approximates 1 in healthy subjects and in patients with normal lung elastic recoil (LER). LER is lower and the total lung capacity is higher in lung obstructive diseases. Consequently, the total lung compliance could increase and FCLE could grow up to 10 in such cases (for instance, in severe emphysema). This leads to increasing lung activity on overcoming the elastic resistance up to 10 kgf × m / min or higher. Actually, this huge work of breathing is not performed due to the 2nd level of lung mechanical activity that is an active dilation of the large airways on expiration; this mechanism prevents valvular bronchial obstruction.

The comparison of main operational indicators for the naturally aspirated and supercharged engines

Combustion engines are currently the leading source of mechanical energy in the sector of goods and people transport. Indispensable element of engines development is operational indicators rise. These indicators are direct criteria of comparison and they allow assessment of specific power level of each construction. It can be observed, that in the era of charge exchange systems the naturally aspirated engines are still available in common application. In the paper the main indicators and specific parameters for newest engines have been compared; the engines design has been described as well and classified by their application.

Recent progress in piezoelectric nanogenerators as a sustainable power source in self-powered systems and active sensors

Mechanical energy sources are abundant in our living environment, such as body motion, vehicle transportation, engine vibrations and breezy wind, which have been underestimated in many cases. They could be converted into electrical energy and utilized for many purposes, including driving small electronic devices or even constructing an integrated system operated without bulky batteries and power cables. Many progresses have been made recently in the mechanical energy harvesting technology based on piezoelectric nanogenerators (PENGs). By introducing a new sandwich structure design, high performance PENGs can be achieved through very simple fabrication process with good mechanical stability by utilizing ZnO nanowires (NWs). By further optimizing the nanomaterials׳ properties and device structure, the PENG׳s open circuit (OC) voltage can be elevated to over 37V. Two important applications of this technology are that the nanogenerator can be used as a sustainable power source for self-powered system and can worked as active sensors. Several demonstrations are reviewed here. Finally, perspectives of this mechanical energy harvesting technology are discussed. Co-operation with power management circuit, capability of integrating with a system, and low cost large-scale manufacturing processing are suggested to be the key points toward commercialization of PENGs.

Biodiesel from Seeds: An Experiment for Organic Chemistry

Plants can store the chemical energy required by their developing offspring in the form of triglycerides. These lipids can be isolated from seeds and then converted into biodiesel through a transesterification reaction. This second-year undergraduate organic chemistry laboratory experiment exemplifies the conversion of an agricultural energy source directly into a mechanical energy source.

ON THE IMPACT OF RADIATION PRESSURE ON THE DYNAMICS AND INNER STRUCTURE OF DUSTY WIND-DRIVEN SHELLS

Massive young stellar clusters are strong sources of radiation and mechanical energy. Their powerful winds and radiation pressure sweep-up interstellar gas into thin expanding shells which trap the ionizing radiation produced by the central clusters affecting the dynamics and the distribution of their ionized gas. Here we continue our comparison of the star cluster winds and radiation pressure effects on the dynamics of shells around young massive clusters. We calculate the impact that radiation pressure has on the distribution of matter and thermal pressure within such shells as well as on the density weighted ionization parameter $U_w$ and put our results on the diagnostic diagram which allows one to discriminate between the wind-dominated and radiation-dominated regimes. We found that model predicted values of the ionization parameter agree well with typical values found in local starburst galaxies. Radiation pressure may affect the inner structure and the dynamics of wind-driven shells only at the earliest stages of evolution or if a major fraction of the star cluster mechanical luminosity is dissipated or radiated away within the star cluster volume and thus the star cluster mechanical energy output is significantly smaller than star cluster synthetic models predict. However, even in these cases radiation dominates over the wind dynamical pressure only if the exciting cluster is embedded into a high density ambient medium.

A flexible hybrid strain energy harvester using piezoelectric and electrostatic conversion

A new design of flexible energy harvester to utilize piezoelectric and electrostatic energy conversion mechanisms simultaneously from a single mechanical energy source is proposed. This non-resonant type harvester enables low-frequency mechanical inputs to be converted to electricity, and the polymeric structures make the harvester mechanically flexible, allowing it to be applied to non-planar surfaces. The fabricated harvester generated peak- and average power densities of 159 and 1.79 μW cm−2 respectively by piezoelectric conversion, and 52.9 μW cm−2 and 1.59 nW cm−2 respectively by electrostatic conversion from an input force of 1.2 N at 3 Hz. Considering its flexibility and ability to harvest mechanical inputs at frequencies below 3 Hz, low-frequency human movements could be a potential energy source for the proposed hybrid harvester to exploit.

Solar Air-Conditioning: Design for a Compressor-Less System using Peltier Effect

Air-conditioning is one of the major consumers of electrical energy in many parts of the world today and already today air-conditioning causes energy shortage in for example China. The demand can be expected to increase because of changing working times, increased comfort expectations and global warming. Air-conditioning systems in use are most often built around a vapour compression system driven by grid-electricity. However, most ways of generating the electricity today, as well as the refrigerants being used in traditional vapour compression systems, have negative impact on the environment. Solar air-conditioning might be a way to reduce the demand for electricity. In addition many solar air-conditioning systems are constructed in ways that eliminate the need for CFC, HCFC or HFC refrigerants. This research work is based on the Peltier effect with which we can cool a specific area without using compressor which take a huge consumption of electricity. And this system is driven by solar energy using solar plates, battery, transformer peltier module and heat sink. This paper deals with a wide range of components, from room air-conditioners to solar.Conventional compressor run cooling devices have many drawbacks pertaining to energy efficiency and the use of CFC refrigerants. Both these factors indirectly point to the impending scenario of global warming. As most of the electricity generation relies on the coal power plants, which add greenhouse gases to the atmosphere is the major cause of global warming. Although researches are going on, better alternatives for the CFC refrigerants is still on the hunt. So instead of using conventional air conditioning systems, other products which can efficiently cool a person are to be devised. By using other efficient cooling mechanisms we can save the electricity bills and also control the greenhouse gases that are currently released into the atmosphere .Air-conditioning is one of the major. Collectors, which can be used as subcomponents in a solar air-conditioning system. However, most of the components and subsystems covered are not only suitable for solar air-conditioning. Some components are used for electrically, mechanically or heat driven air-conditioning. And of course other sources of mechanical energy or heat could be used for powering these components. Other components are used for solar energy collection and storage, which can be used in solar energy system with other purposes than just driving a solar air-conditioning system. In this research work the idea was to build an alternative for AC and to provide Air conditioning effect. The research aims to design and build a miniature prototype of thermoelectric cooling system for a conventional air conditioned to provide air conditioning to reduce the consumption of electricity and to reduce the pollution.