Power Conditioning for MEMS-Based Waste Vibrational Energy Harvester
2015-06-01
Energy Harvester 15. NUMBER OF PAGES 53 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT Unclassified 18. SECURITY CLASSIFICATION OF THIS...FOR MEMS-BASED WASTE VIBRATIONAL ENERGY HARVESTER by Seyfullah Emen June 2015 Thesis Advisor: Dragoslav Grbovic Co-Advisor: Sherif...COVERED Master’s Thesis 4. TITLE AND SUBTITLE POWER CONDITIONING FOR MEMS-BASED WASTE VIBRATIONAL ENERGY HARVESTER 5. FUNDING NUMBERS 6. AUTHOR
NASA Astrophysics Data System (ADS)
Takei, Ryohei; Okada, Hironao; Makimoto, Natsumi; Itoh, Toshihiro; Kobayashi, Takeishi
2016-10-01
We developed a power management circuit for piezoelectric microelectromechanical system cantilever vibration energy harvesters (VEHs) with ultralow-power consumption. The power management circuit was effective in a wireless vibration monitoring system. To operate the system, ultralow-power electronics were required because only a small amount of electrical power was generated from the faint environmental vibration. Pb(Zr,Ti)O3 (PZT) and aluminum nitride (AlN) VEHs were fabricated and their equivalent circuits were extracted from output voltage measurements. The power management circuit was simulated using the extracted circuits. The simulation suggested that the power management circuit can be driven by a vibration acceleration of 1.0 m/s2 by lowering the power consumption of the power management circuit using existing electronics.
NASA Astrophysics Data System (ADS)
Renaud, M.; Elfrink, R.; Jambunathan, M.; de Nooijer, C.; Wang, Z.; Rovers, M.; Vullers, R.; van Schaijk, R.
2012-10-01
Assuming a sinusoidal vibration as input, an inertial piezoelectric harvester designed for maximum efficiency of the electromechanical energy conversion does not always lead to maximum power generation. In this case, what can be gained by optimizing the efficiency of the device? Detailing an answer to this question is the backbone of this paper. It is shown that, while the maximum efficiency operating condition does not always lead to maximum power generation, it corresponds always to maximum power per square unit deflection of the piezoelectric harvester. This understanding allows better optimization of the generated power when the deflection of the device is limited by hard stops. This is illustrated by experimental measurements on vacuum-packaged MEMS harvesters based on AlN as piezoelectric material. The results obtained for a sinusoidal vibration are extended to random vibrations. In this case, we demonstrate that the optimum generated power is directly proportional to the efficiency of the harvester, thus answering the initial question. For both types of studied vibrations, simple closed-form formulas describing the generated power and efficiency in optimum operating conditions are elaborated. These formulas are based on parameters that are easily measured or modeled. Therefore, they are useful performance metrics for existing piezoelectric harvesters.
Harvesting Ambient Vibration Energy over a Wide Frequency Range for Self-Powered Electronics.
Wang, Xiaofeng; Niu, Simiao; Yi, Fang; Yin, Yajiang; Hao, Chenglong; Dai, Keren; Zhang, Yue; You, Zheng; Wang, Zhong Lin
2017-02-28
Vibration is one of the most common energy sources in ambient environment. Harvesting vibration energy is a promising route to sustainably drive small electronics. This work introduces an approach to scavenge vibrational energy over a wide frequency range as an exclusive power source for continuous operation of electronics. An elastic multiunit triboelectric nanogenerator (TENG) is rationally designed to efficiently harvest low-frequency vibration energy, which can provide a maximum instantaneous output power density of 102 W·m(-3) at as low as 7 Hz and maintain its stable current outputs from 5 to 25 Hz. A self-charging power unit (SCPU) combining the TENG and a 10 mF supercapacitor gives a continuous direct current (DC) power delivery of 1.14 mW at a power management efficiency of 45.6% at 20 Hz. The performance of the SCPU can be further enhanced by a specially designed power management circuit, with a continuous DC power of 2 mW and power management efficiency of 60% at 7 Hz. Electronics such as a thermometer, hygrometer, and speedometer can be sustainably powered solely by the harvested vibration energy from a machine or riding bicycle. This approach has potential applications in self-powered systems for environment monitoring, machine safety, and transportation.
NASA Astrophysics Data System (ADS)
Beeby, Stephen P.; Wang, Leran; Zhu, Dibin; Weddell, Alex S.; Merrett, Geoff V.; Stark, Bernard; Szarka, Gyorgy; Al-Hashimi, Bashir M.
2013-07-01
The design of vibration energy harvesters (VEHs) is highly dependent upon the characteristics of the environmental vibrations present in the intended application. VEHs can be linear resonant systems tuned to particular frequencies or nonlinear systems with either bistable operation or a Duffing-type response. This paper provides detailed vibration data from a range of applications, which has been made freely available for download through the Energy Harvesting Network’s online data repository. In particular, this research shows that simulation is essential in designing and selecting the most suitable vibration energy harvester for particular applications. This is illustrated through C-based simulations of different types of VEHs, using real vibration data from a diesel ferry engine, a combined heat and power pump, a petrol car engine and a helicopter. The analysis shows that a bistable energy harvester only has a higher output power than a linear or Duffing-type nonlinear energy harvester with the same Q-factor when it is subjected to white noise vibration. The analysis also indicates that piezoelectric transduction mechanisms are more suitable for bistable energy harvesters than electromagnetic transduction. Furthermore, the linear energy harvester has a higher output power compared to the Duffing-type nonlinear energy harvester with the same Q factor in most cases. The Duffing-type nonlinear energy harvester can generate more power than the linear energy harvester only when it is excited at vibrations with multiple peaks and the frequencies of these peaks are within its bandwidth. Through these new observations, this paper illustrates the importance of simulation in the design of energy harvesting systems, with particular emphasis on the need to incorporate real vibration data.
Powering pacemakers from heartbeat vibrations using linear and nonlinear energy harvesters
NASA Astrophysics Data System (ADS)
Amin Karami, M.; Inman, Daniel J.
2012-01-01
Linear and nonlinear piezoelectric devices are introduced to continuously recharge the batteries of the pacemakers by converting the vibrations from the heartbeats to electrical energy. The power requirement of a pacemaker is very low. However, after few years, patients require another surgical operation just to replace their pacemaker battery. Linear low frequency and nonlinear mono-stable and bi-stable energy harvesters are designed according to the especial signature of heart vibrations. The proposed energy harvesters are robust to variation of heart rate and can meet the power requirement of pacemakers.
NASA Astrophysics Data System (ADS)
Ren, Long; Chen, Renwen; Xia, Huakang; Zhang, Xiaoxiao
2016-04-01
To supply power to wireless sensor networks, a type of broadband electromagnetic vibration energy harvester (VEH) using bistable vibration scavenging structure is proposed. It consists of a planar spring, an electromagnetic transducer with an annular magnetic circuit, and a coil assembly with a ferrite bobbin inside. A nonlinear magnetic force respecting to the relative displacement is generated by the ferrite bobbin, and to broaden the working frequency bandwidth of the VEH. Moreover, the ferrite bobbin increases the magnetic flux linkage gradient of the coil assembly in its moving region, and further to improve its output voltage. The dynamic behaviors of the VEH are analyzed and predicted by finite element analysis and ODE calculation. Validation experiments are carried out and show that the VEH can harvest high energy in a relatively wide excitation frequency band. The further test shows that the load power of the VEH with a load resistor of 90Ω can reach 10mW level in a wide frequency bandwidth when the acceleration level of the harmonic excitation is 1g. It can ensure the intermittent work of many sensors as well as wireless communication modules at least.
NASA Astrophysics Data System (ADS)
Grabham, N. J.; Harden, C.; Vincent, D.; Beeby, S. P.
2016-11-01
A wirelessly powered remote sensor node is presented along with its design process. The purpose of the node is the further expansion of the sensing capabilities of the commercial Perpetuum system used for condition monitoring on trains and rolling stock which operates using vibration energy harvesting. Surplus harvested vibration energy is transferred wirelessly to a remote satellite sensor to allow measurements over a wider area to be made. This additional data is to be used for long term condition monitoring. Performance measurements made on the prototype remote sensor node are reported and advantages and disadvantages of using the same RF frequency for power and data transfer are identified.
Kim, Moonkeun; Lee, Sang-Kyun; Ham, Yong-Hyun; Yang, Yil Suk; Kwon, Jong-Kee; Kwon, Kwang-Ho
2012-08-01
We designed and fabricated a bimorph cantilever array for sustainable power with an integrated Cu proof mass to obtain additional power and current. We fabricated a cantilever system using single-crystal piezoelectric material and compared the calculations for single and arrayed cantilevers to those obtained experimentally. The vibration energy harvester had resonant frequencies of 60.4 and 63.2 Hz for short and open circuits, respectively. The damping ratio and quality factor of the cantilever device were 0.012 and 41.66, respectively. The resonant frequency at maximum average power was 60.8 Hz. The current and highest average power of the harvester array were found to be 0.728 mA and 1.61 mW, respectively. The sustainable maximum power was obtained after slightly shifting the short-circuit frequency. In order to improve the current and power using an array of cantilevers, we also performed energy conversion experiments.
A Vibration-Based MEMS Piezoelectric Energy Harvester and Power Conditioning Circuit
Yu, Hua; Zhou, Jielin; Deng, Licheng; Wen, Zhiyu
2014-01-01
This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of the harvester, and harmonic analysis is performed to investigate the influence of the geometric parameters on the output voltage. Based on simulation results, a MEMS Pb(Zr,Ti)O3 (PZT) cantilever array with an integrated large Si proof mass is designed and fabricated to improve output voltage and power. Test results show that the fabricated generator, with five cantilever beams (with unit dimensions of about 3 × 2.4 × 0.05 mm3) and an individual integrated Si mass dimension of about 8 × 12.4 × 0.5 mm3, produces a output power of 66.75 μW, or a power density of 5.19 μW·mm−3·g−2 with an optimal resistive load of 220 kΩ from 5 m/s2 vibration acceleration at its resonant frequency of 234.5 Hz. In view of high internal impedance characteristic of the PZT generator, an efficient autonomous power conditioning circuit, with the function of impedance matching, energy storage and voltage regulation, is then presented, finding that the efficiency of the energy storage is greatly improved and up to 64.95%. The proposed self-supplied energy generator with power conditioning circuit could provide a very promising complete power supply solution for wireless sensor node loads. PMID:24556670
A vibration-based MEMS piezoelectric energy harvester and power conditioning circuit.
Yu, Hua; Zhou, Jielin; Deng, Licheng; Wen, Zhiyu
2014-02-19
This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of the harvester, and harmonic analysis is performed to investigate the influence of the geometric parameters on the output voltage. Based on simulation results, a MEMS Pb(Zr,Ti)O3 (PZT) cantilever array with an integrated large Si proof mass is designed and fabricated to improve output voltage and power. Test results show that the fabricated generator, with five cantilever beams (with unit dimensions of about 3 × 2.4 × 0.05 mm3) and an individual integrated Si mass dimension of about 8 × 12.4 × 0.5 mm3, produces a output power of 66.75 μW, or a power density of 5.19 μW∙mm-3∙g-2 with an optimal resistive load of 220 kΩ from 5 m/s2 vibration acceleration at its resonant frequency of 234.5 Hz. In view of high internal impedance characteristic of the PZT generator, an efficient autonomous power conditioning circuit, with the function of impedance matching, energy storage and voltage regulation, is then presented, finding that the efficiency of the energy storage is greatly improved and up to 64.95%. The proposed self-supplied energy generator with power conditioning circuit could provide a very promising complete power supply solution for wireless sensor node loads.
NASA Astrophysics Data System (ADS)
Truong, Binh Duc; Phu Le, Cuong; Halvorsen, Einar
2016-12-01
This paper presents experiments on how to approach the physical limits on power from vibration energy harvesting under displacement-constrained operation. A MEMS electrostatic vibration energy harvester with voltage-control of the system stiffness is used for this purpose. The power saturation problem, when the proof-mass displacement reaches a maximum amplitude for sufficient acceleration amplitude, is shifted to higher accelerations by use of load optimization. In addition, we demonstrate the effect of varying the electromechanical coupling k 2. Measurement results show that harvested power can also be made to follow the optimal power of the velocity-damped generator for a range of accelerations, which implies displacement constraints. Compared to the saturated power, the power increases 1.5 times with the optimal load for electromechanical coupling at k 2 = 8.7%. This is improved 2.3 times for a higher coupling of {{k}2}=17.9 % . The obtained system effectiveness exceeds 60%. This work shows a first demonstration of reaching optimal power in the intermediate acceleration-range between the two extremes of maximum efficiency and maximum power transfer. The experimental results follow the theoretical results for a device with both load and stiffness tuning surprisingly well, despite only optimizing the load here. We compared a linearized lumped-model of the device with the same augmented by end-stop nonlinearities. The comparison shows that an effective stiffness due to end-stop impacts in the latter model closely matches the optimal stiffness for the former model, and therefore can explain why the experimental output power is close to optimal despite the lack of deliberate stiffness tuning.
NASA Astrophysics Data System (ADS)
Zilletti, Michele; Elliott, Stephen J.; Rustighi, Emiliano
2012-08-01
The tuning of a dynamic vibration absorber is considered such that either the kinetic energy of the host structure is minimised or the power dissipation within the absorber is maximised. If the host structure is approximated as a damped single degree of freedom, the optimal values for the ratio of the absorber's natural frequency to the host structure and the optimal damping ratio of the absorber are shown to be the same whether the kinetic energy of the host structure is minimised or the power dissipation of the absorber is maximised. It is also demonstrated that the total power input into the system does not depend on the two parameters but only on the host structure's mass.
Broadband electromagnetic vibration energy harvesting system for powering wireless sensor nodes
NASA Astrophysics Data System (ADS)
Marin, Anthony; Turner, John; Ha, Dong Sam; Priya, Shashank
2013-07-01
This paper reports the design of an electromagnetic vibration energy harvesting system that provides high power density and broad bandwidth. The ‘double cell’ harvester was chosen as the generator for this system. In order to harvest power over a broad range of frequencies, four ‘double cell’ harvesters with varying resonances were incorporated in the system architecture. The average AC to regulated DC power conversion efficiency across the 4 Hz bandwidth was 78%, which is one of the highest reported magnitudes for an electromagnetic vibration harvesting system. The magnetic flux density variation within the double cell array was modeled using the finite element method and compared to a single cell with equivalent tip mass and magnet volume. The double cell array was found to generate a similar magnitude of power to a single cell but three times higher bandwidth. The average generator conversion efficiency for the double cell array was 45.3%, which approaches the maximum theoretical limit of 50%.
NASA Astrophysics Data System (ADS)
Du, Sijun; Chen, Shao-Tuan; Jia, Yu; Arroyo, Emmanuelle; Seshia, Ashwin
2016-11-01
Among the various methods of extracting energy harvested by a piezoelectric vibration energy harvester, full-bridge rectifiers (FBR) are widely employed due to its simplicity and stability. However, its efficiency and operational range are limited due to a threshold voltage that the open-circuit voltage generated from the piezoelectric transducer (PT) must attain prior to any energy extraction. This voltage linearly depends on the output voltage of the FBR and the forward voltage drop of diodes and the nature of the interface can significantly limit the amount of extracted energy under low excitation levels. In this paper, a passive scheme is proposed to split the electrode of a micromachined PT into multiple (n) equal regions, which are electrically connected in series. The power output from such a series connected MEMS PT allows for the generated voltage to readily overcome the threshold set by the FBR. Theoretical calculations have been performed in this paper to assess the performance for different series stages (n values) and the theory has been experimentally validated. The results show that a PT with more series stages (high n values) improves the efficiency of energy extraction relative to the case with fewer series-connected stages under weak excitation levels.
NASA Astrophysics Data System (ADS)
Uluşan, H.; Gharehbaghi, K.; Zorlu, Ö.; Muhtaroğlu, A.; Külah, H.
2015-12-01
This study presents a novel hybrid system that combines the power generated simultaneously by a vibration-based Electromagnetic (EM) harvester and a UHF band RF harvester. The novel hybrid scavenger interface uses a power management circuit in 180 nm CMOS technology to step-up and to regulate the combined output. At the first stage of the system, the RF harvester generates positive DC output with a 7-stage threshold compensated rectifier, while the EM harvester generates negative DC output with a self-powered AC/DC negative doubler circuit. At the second stage, the generated voltages are serially added, stepped-up with an on-chip charge pump circuit, and regulated to a typical battery voltage of 3 V. Test results indicate that the hybrid operation enables generation of 9 μW at 3 V output for a wide range of input stimulations, which could not be attained with either harvesting mode by itself. Moreover the hybrid system behaves as a typical battery, and keeps the output voltage stable at 3 V up to 18 μW of output power. The presented system is the first battery-like harvester to our knowledge that generates energy from two independent sources and regulates the output to a stable DC voltage.
NASA Astrophysics Data System (ADS)
Chandrasekharan, Nataraj
Innovation in integrated circuit technology along with improved manufacturing processes has resulted in considerable reduction in power consumption of electromechanical devices. Majority of these devices are currently powered by batteries. However, the issues posed by batteries, including the need for frequent battery recharge/replacement has resulted in a compelling need for alternate energy to achieve self-sufficient device operation or to supplement battery power. Vibration based energy harvesting methods through piezoelectric transduction provides with a promising potential towards replacing or supplementing battery power source. However, current piezoelectric energy harvesters generate low specific power (power-to-weight ratio) when compared to batteries that the harvesters seek to replace or supplement. In this study, the potential of integrating lightweight cellular honeycomb structures with existing piezoelectric device configurations (bimorph) to achieve higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of a conventional piezoelectric bimorph with honeycomb structures of the same material results in a significant increase in power-to-weight ratio of the piezoelectric harvester. In order to maximize the electrical response of vibration based power harvesters, the natural frequency of these harvesters is designed to match the input driving frequency. The commonly used technique of adding a tip mass is employed to lower the natural frequency (to match driving frequency) of both, solid and honeycomb substrate bimorphs. At higher excitation frequency, the natural frequency of the traditional solid substrate bimorph can only be altered (to match driving frequency) through a change in global geometric design parameters, typically achieved by increasing the thickness of the harvester. As a result, the size of the harvester is increased and can be disadvantageous
NASA Astrophysics Data System (ADS)
Iannacci, J.; Sordo, G.; Serra, E.; Kucera, M.; Schmid, U.
2015-05-01
In this work, we discuss the verification and preliminary experimental characterization of a MEMS-based vibration Energy Harvester (EH) design. The device, named Four-Leaf Clover (FLC), is based on a circular-shaped mechanical resonator with four petal-like mass-spring cascaded systems. This solution introduces several mechanical Degrees of Freedom (DOFs), and therefore enables multiple resonant modes and deformation shapes in the vibrations frequency range of interest. The target is to realize a wideband multi-modal EH-MEMS device, that overcomes the typical narrowband working characteristics of standard cantilevered EHs, by ensuring flexible and adaptable power source to ultra-low power electronics for integrated remote sensing nodes (e.g. Wireless Sensor Networks - WSNs) in the Internet of Things (IoT) scenario, aiming to self-powered and energy autonomous smart systems. Finite Element Method simulations of the FLC EH-MEMS show the presence of several resonant modes for vibrations up to 4-5 kHz, and level of converted power up to a few μW at resonance and in closed-loop conditions (i.e. with resistive load). On the other hand, the first experimental tests of FLC fabricated samples, conducted with a Laser Doppler Vibrometer (LDV), proved the presence of several resonant modes, and allowed to validate the accuracy of the FEM modeling method. Such a good accordance holds validity for what concerns the coupled field behavior of the FLC EH-MEMS, as well. Both measurements and simulations performed at 190 Hz (i.e. out of resonance) showed the generation of power in the range of nW (Root Mean Square - RMS values). Further steps of this work will include the experimental characterization in a full range of vibrations, aiming to prove the whole functionality of the FLC EH-MEMS proposed design concept.
Kim, Moonkeun; Lee, Sang-Kyun; Yang, Yil Suk; Jeong, Jaehwa; Min, Nam Ki; Kwon, Kwang-Ho
2013-12-01
We fabricated dual-beam cantilevers on the microelectromechanical system (MEMS) scale with an integrated Si proof mass. A Pb(Zr,Ti)O3 (PZT) cantilever was designed as a mechanical vibration energy-harvesting system for low power applications. The resonant frequency of the multilayer composition cantilevers were simulated using the finite element method (FEM) with parametric analysis carried out in the design process. According to simulations, the resonant frequency, voltage, and average power of a dual-beam cantilever was 69.1 Hz, 113.9 mV, and 0.303 microW, respectively, at optimal resistance and 0.5 g (gravitational acceleration, m/s2). Based on these data, we subsequently fabricated cantilever devices using dual-beam cantilevers. The harvested power density of the dual-beam cantilever compared favorably with the simulation. Experiments revealed the resonant frequency, voltage, and average power density to be 78.7 Hz, 118.5 mV, and 0.34 microW, respectively. The error between the measured and simulated results was about 10%. The maximum average power and power density of the fabricated dual-beam cantilever at 1 g were 0.803 microW and 1322.80 microW cm(-3), respectively. Furthermore, the possibility of a MEMS-scale power source for energy conversion experiments was also tested.
Vibration Testing of Stirling Power Convertors
NASA Technical Reports Server (NTRS)
Hughes, Bill; Goodnight, Thomas; McNelis, Mark E.; Suarez, Vicente J.; Schreiber, Jeff; Samorezov, Sergey
2003-01-01
The NASA John H. Glenn Research Center (GRC) and the U.S. Department of Energy (DOE) are currently developing a high efficient, long life, free piston Stirling convertor for use as an advanced spacecraft power system for future NASA missions. As part of this development, a Stirling Technology Demonstrator Convertor (TDC), developed by Stirling Technology Company (STC) for DOE, was vibration tested at GRC s Structural Dynamics Laboratory (SDU7735) in November- December 1999. This testing demonstrated that the Stirling TDC is able to withstand the harsh random vibration (20 to 2000 Hertz) seen during a typical spacecraft launch and survive with no structural damage or functional power performance degradation, thereby enabling its usage in future spacecraft power systems. The Stirling Vibration Test Team at NASA GRC and STC personnel conducted tests on a single 55 electric watt TDC. The purpose was to characterize the TDC s structural response to vibration and determine if the TDC could survive the vibration criteria established by the Jet Propulsion Laboratory (JPL) for launch environments. The TDC was operated at full-stroke and full power conditions during the vibration testing. The TDC was tested in two orientations, with the direction of vibration parallel and perpendicular to the TDC s moving components (displacer and piston). The TDC successfully passed a series of sine and random vibration tests. The most severe test was a 12.3 Grms random vibration test (peak vibration level of 0.2 g2/Hz from 50 to 250 Hertz) with test durations of 3 minutes per axis. The random vibration test levels were chosen to simulate, with margin, the maximum anticipated launch vibration conditions. As a result of this very successful vibration testing and successful evaluations in other key technical readiness areas, the Stirling power system is now considered a viable technology for future application for NASA spacecraft missions. Possible usage of the Stirling power system would be
Vibration shape effects on the power output in piezoelectric vibro-impact energy harvesters
NASA Astrophysics Data System (ADS)
Twiefel, Jens
2013-04-01
Vibro-Impcact harvesting devices are one concept to increase the bandwidth of resonant operated piezoelectric vibration generators. The fundamental setup is a piezoelectric bending element, where the deflection is limited by two stoppers. After starting the system in resonance operation the bandwidth increases towards higher frequencies as soon the deflection reach the stopper. If the stoppers are rigid, the frequency response gives constant amplitude for increasing frequencies, as long the system is treated as ideal one-DOF system with symmetric stoppers. In consequence, the bandwidth is theoretically unlimited large. However, such a system also has two major drawbacks, firstly the complicated startup mechanism and secondly the tendency to drop from the high constant branch in the frequency response on the much smaller linear branch if the system is disturbed. Nevertheless, the system has its application wherever the startup problem can be solved. Most modeling approaches utilize modal one-DOF models to describe the systems behavior and do not tread the higher harmonics of the beam. This work investigates the effects of the stoppers on the vibration shape of the piezoelectric beam, wherefore a finite element model is used. The used elements are one-dimensional two node elements based on the Timoshenko-beam theory. The finite element code is implemented in Matlab. The model is calculated utilizing time step integration for simulation, to reduce the computation time an auto-resonant calculation method is implemented. A control loop including positive feedback and saturation is used to create a self-excited system. Therefore, the system is always operated in resonance (on the backbone curve) and the frequency is a direct result of the computation. In this case tip velocity is used as feedback. This technique allows effective parametric studies. Investigated parameters include gap, excitation amplitude, tip mass as well as the stiffness of the stopper. The stress and
Molecular vibrational energy flow
NASA Astrophysics Data System (ADS)
Gruebele, M.; Bigwood, R.
This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental studies. We consider the problem in various representations, and use these to develop a family of simple models which combine specific molecular properties (e.g. size, vibrational frequencies) with statistical properties of the potential energy surface and wavefunctions. This marriage of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate time regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate time IVR differs in many aspects from the early stages of hydrogenic mode IVR. As a result, IVR can be coherently frozen, with potential applications to selective chemistry.
Fernando, Joseph S; Sun, Qiao
2013-11-01
A vibration harvester is usually designed to work in resonance responding to source vibration. Many existing types of harvesters use a single mechanical resonator to amplify the excitation vibrations. However, these harvesters are inherently limited in the amount of power that they can produce, due to their design, particularly in the limited number of design parameters. In our study, we propose a two-stage design to improve a harvester's performance both in power production and in bandwidth widening. In this paper, we demonstrate that a two-stage design can increase the power production when the device is intended to operate under a single frequency excitation. Harvester parameters are optimized to provide maximum power production. Power production comparisons between single-stage and two-stage harvesters are made through numerical simulation and experiments.
Energy scavenging from environmental vibration.
Galchev, Tzeno; Apblett, Christopher Alan; Najafi, Khalil
2009-10-01
The goal of this project is to develop an efficient energy scavenger for converting ambient low-frequency vibrations into electrical power. In order to achieve this a novel inertial micro power generator architecture has been developed that utilizes the bi-stable motion of a mechanical mass to convert a broad range of low-frequency (< 30Hz), and large-deflection (>250 {micro}m) ambient vibrations into high-frequency electrical output energy. The generator incorporates a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromagnetic scavenger. This frequency up-conversion technique enhances the electromechanical coupling and increases the generated power. This architecture is called the Parametric Frequency Increased Generator (PFIG). Three generations of the device have been fabricated. It was first demonstrated using a larger bench-top prototype that had a functional volume of 3.7cm3. It generated a peak power of 558{micro}W and an average power of 39.5{micro}W at an input acceleration of 1g applied at 10 Hz. The performance of this device has still not been matched by any other reported work. It yielded the best power density and efficiency for any scavenger operating from low-frequency (<10Hz) vibrations. A second-generation device was then fabricated. It generated a peak power of 288{micro}W and an average power of 5.8{micro}W from an input acceleration of 9.8m/s{sup 2} at 10Hz. The device operates over a frequency range of 20Hz. The internal volume of the generator is 2.1cm{sup 3} (3.7cm{sup 3} including casing), half of a standard AA battery. Lastly, a piezoelectric version of the PFIG is currently being developed. This device clearly demonstrates one of the key features of the PFIG architecture, namely that it is suitable for MEMS integration, more so than resonant generators, by incorporating a brittle bulk piezoelectric ceramic. This is the first micro-scale piezoelectric generator capable of <10Hz operation. The
Vibration energy harvester optimization using artificial intelligence
NASA Astrophysics Data System (ADS)
Hadas, Z.; Ondrusek, C.; Kurfurst, J.; Singule, V.
2011-06-01
This paper deals with an optimization study of a vibration energy harvester. This harvester can be used as autonomous source of electrical energy for remote or wireless applications, which are placed in environment excited by ambient mechanical vibrations. The ambient energy of vibrations is usually on very low level but the harvester can be used as alternative source of energy for electronic devices with an expected low level of power consumption of several mW. The optimized design of the vibration energy harvester was based on previous development and the sensitivity of harvester design was improved for effective harvesting from mechanical vibrations in aeronautic applications. The vibration energy harvester is a mechatronic system which generates electrical energy from ambient vibrations due to precision tuning up generator parameters. The optimization study for maximization of harvested power or minimization of volume and weight are the main goals of our development. The optimization study of such complex device is complicated therefore artificial intelligence methods can be used for tuning up optimal harvester parameters.
2009-09-01
referred to as solar cells or PV arrays. First recorded by French Scientist Edmund Becquerel in 1839, the photovoltaic effect is a simple physical process... solar cell array matched for electrostatic MEMS capable of providing power with an upper voltage potential of 150 V and currents in the nA to µA range...The team used a hydrogenated amorphous silicon (a-Si:H) to optimize their solar array design. Each cell is comprised of a triple layer of P-N
Harvesting Vibrational Energy Using Material Work Functions
Varpula, Aapo; Laakso, Sampo J.; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika
2014-01-01
Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications. PMID:25348004
Frequency adjustable MEMS vibration energy harvester
NASA Astrophysics Data System (ADS)
Podder, P.; Constantinou, P.; Amann, A.; Roy, S.
2016-10-01
Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.
Wireless Inductive Power Device Suppresses Blade Vibrations
NASA Technical Reports Server (NTRS)
Morrison, Carlos R.; Provenza, Andrew J.; Choi, Benjamin B.; Bakhle, Milind A.; Min, James B.; Stefko, George L.; Duffy, Kirsten P.; Fougers, Alan J.
2011-01-01
Vibration in turbomachinery can cause blade failures and leads to the use of heavier, thicker blades that result in lower aerodynamic efficiency and increased noise. Metal and/or composite fatigue in the blades of jet engines has resulted in blade destruction and loss of lives. Techniques for suppressing low-frequency blade vibration, such as gtuned circuit resistive dissipation of vibratory energy, h or simply "passive damping," can require electronics incorporating coils of unwieldy dimensions and adding unwanted weight to the rotor. Other approaches, using vibration-dampening devices or damping material, could add undesirable weight to the blades or hub, making them less efficient. A wireless inductive power device (WIPD) was designed, fabricated, and developed for use in the NASA Glenn's "Dynamic Spin Rig" (DSR) facility. The DSR is used to simulate the functionality of turbomachinery. The relatively small and lightweight device [10 lb (approx.=4.5 kg)] replaces the existing venerable and bulky slip-ring. The goal is the eventual integration of this technology into actual turbomachinery such as jet engines or electric power generators, wherein the device will facilitate the suppression of potentially destructive vibrations in fan blades. This technology obviates slip rings, which require cooling and can prove unreliable or be problematic over time. The WIPD consists of two parts: a remote element, which is positioned on the rotor and provides up to 100 W of electrical power to thin, lightweight piezoelectric patches strategically placed on/in fan blades; and a stationary base unit that wirelessly communicates with the remote unit. The base unit supplies inductive power, and also acts as an input and output corridor for wireless measurement, and active control command to the remote unit. Efficient engine operation necessitates minimal disturbance to the gas flow across the turbine blades in any effort to moderate blade vibration. This innovation makes it
Vibration energy harvesting by magnetostrictive material
NASA Astrophysics Data System (ADS)
Wang, Lei; Yuan, F. G.
2008-08-01
A new class of vibration energy harvester based on magnetostrictive material (MsM), Metglas 2605SC, is designed, developed and tested. It contains two submodules: an MsM harvesting device and an energy harvesting circuit. Compared to piezoelectric materials, the Metglas 2605SC offers advantages including higher energy conversion efficiency, longer life cycles, lack of depolarization and higher flexibility to survive in strong ambient vibrations. To enhance the energy conversion efficiency and alleviate the need of a bias magnetic field, Metglas ribbons are transversely annealed by a strong magnetic field along their width direction. To analyze the MsM harvesting device a generalized electromechanical circuit model is derived from Hamilton's principle in conjunction with the normal mode superposition method based on Euler-Bernoulli beam theory. The MsM harvesting device is equivalent to an electromechanical gyrator in series with an inductor. In addition, the proposed model can be readily extended to a more practical case of a cantilever beam element with a tip mass. The energy harvesting circuit, which interfaces with a wireless sensor and accumulates the harvested energy into an ultracapacitor, is designed on a printed circuit board (PCB) with plane dimension 25 mm × 35 mm. It mainly consists of a voltage quadrupler, a 3 F ultracapacitor and a smart regulator. The output DC voltage from the PCB can be adjusted within 2.0-5.5 V. In experiments, the maximum output power and power density on the resistor can reach 200 µW and 900 µW cm-3, respectively, at a low frequency of 58 Hz. For a working prototype under a vibration with resonance frequency of 1.1 kHz and peak acceleration of 8.06 m s-2 (0.82 g), the average power and power density during charging the ultracapacitor can achieve 576 µW and 606 µW cm-3, respectively, which compete favorably with piezoelectric vibration energy harvesters.
A MEMS vibration energy harvester for automotive applications
NASA Astrophysics Data System (ADS)
van Schaijk, R.; Elfrink, R.; Oudenhoven, J.; Pop, V.; Wang, Z.; Renaud, M.
2013-05-01
The objective of this work is to develop MEMS vibration energy harvesters for tire pressure monitoring systems (TPMS), they can be located on the rim or on the inner-liner of the car tire. Nowadays TPMS modules are powered by batteries with a limited lifetime. A large effort is ongoing to replace batteries with small and long lasting power sources like energy harvesters [1]. The operation principle of vibration harvesters is mechanical resonance of a seismic mass, where mechanical energy is converted into electrical energy. In general, vibration energy harvesters are of specific interest for machine environments where random noise or repetitive shock vibrations are present. In this work we present the results for MEMS based vibration energy harvesting for applying on the rim or inner-liner. The vibrations on the rim correspond to random noise. A vibration energy harvester can be described as an under damped mass-spring system acting like a mechanical band-pass filter, and will resonate at its natural frequency [2]. At 0.01 g2/Hz noise amplitude the average power can reach the level that is required to power a simple wireless sensor node, approximately 10 μW [3]. The dominant vibrations on the inner-liner consist mainly of repetitive high amplitude shocks. With a shock, the seismic mass is displaced, after which the mass will "ring-down" at its natural resonance frequency. During the ring-down period, part of the mechanical energy is harvested. On the inner-liner of the tire repetitive (one per rotation) high amplitude (few hundred g) shocks occur. The harvester enables an average power of a few tens of μW [4], sufficient to power a more sophisticated wireless sensor node that can measure additional tire-parameters besides pressure. In this work we characterized MEMS vibration energy harvesters for noise and shock excitation. We validated their potential for TPMS modules by measurements and simulation.
Vibrational Power Flow Analysis of Rods and Beams
NASA Technical Reports Server (NTRS)
Wohlever, James Christopher; Bernhard, R. J.
1988-01-01
A new method to model vibrational power flow and predict the resulting energy density levels in uniform rods and beams is investigated. This method models the flow of vibrational power in a manner analogous to the flow of thermal power in a heat conduction problem. The classical displacement solutions for harmonically excited, hysteretically damped rods and beams are used to derive expressions for the vibrational power flow and energy density in the rod and beam. Under certain conditions, the power flow in these two structural elements will be shown to be proportional to the energy density gradient. Using the relationship between power flow and energy density, an energy balance on differential control volumes in the rod and beam leads to a Poisson's equation which models the energy density distribution in the rod and beam. Coupling the energy density and power flow solutions for rods and beams is also discussed. It is shown that the resonant behavior of finite structures complicates the coupling of solutions, especially when the excitations are single frequency inputs. Two coupling formulations are discussed, the first based on the receptance method, and the second on the travelling wave approach used in Statistical Energy Analysis. The receptance method is the more computationally intensive but is capable of analyzing single frequency excitation cases. The traveling wave approach gives a good approximation of the frequency average of energy density and power flow in coupled systems, and thus, is an efficient technique for use with broadband frequency excitation.
A vibration powered wireless mote on the Forth Road Bridge
NASA Astrophysics Data System (ADS)
Jia, Yu; Yan, Jize; Feng, Tao; Du, Sijun; Fidler, Paul; Soga, Kenichi; Middleton, Campbell; Seshia, Ashwin A.
2015-12-01
The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ∼126 cm3, was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent.
Energy evaluation of protection effectiveness of anti-vibration gloves.
Hermann, Tomasz; Dobry, Marian Witalis
2016-10-06
This article describes an energy method of assessing protection effectiveness of anti-vibration gloves on the human dynamic structure. The study uses dynamic models of the human and the glove specified in Standard No. ISO 10068:2012. The physical models of human-tool systems were developed by combining human physical models with a power tool model. The combined human-tool models were then transformed into mathematical models from which energy models were finally derived. Comparative energy analysis was conducted in the domain of rms powers. The energy models of the human-tool systems were solved using numerical simulation implemented in the MATLAB/Simulink environment. The simulation procedure demonstrated the effectiveness of the anti-vibration glove as a method of protecting human operators of hand-held power tools against vibration. The desirable effect is achieved by lowering the flow of energy in the human-tool system when the anti-vibration glove is employed.
A vibration energy harvester using diamagnetic levitation
NASA Astrophysics Data System (ADS)
Palagummi, S.; Yuan, F. G.
2013-04-01
In this paper a novel electromagnetic vibration type energy harvester which uses a diamagnetic levitation system is conceptualized, designed, fabricated, and tested. The harvester uses two diamagnetic plates made of pyrolytic graphite between which a cylindrical magnet levitates passively. Two archimedean spiral coils are placed in grooves which are engraved in the pyrolytic graphite plates, used to convert the mechanical energy into electrical energy efficiently. The geometric configurations of coils are selected based on the field distribution of the magnet to enhance the efficiency of the harvester. A thorough theoretical analysis is done to compare with the experiment results. At an input power of 103.45 μW and at a frequency of 2.7 Hz, the harvester generated a power of 0.744 μW at an efficiency of 0.72 %. Both theoretical and experimental results show that this new energy harvesting system is efficient and can capture low frequency broadband spectra.
Vibration energy harvesting with polyphase AC transducers
NASA Astrophysics Data System (ADS)
McCullagh, James J.; Scruggs, Jeffrey T.; Asai, Takehiko
2016-04-01
Three-phase transduction affords certain advantages in the efficient electromechanical conversion of energy, especially at higher power scales. This paper considers the use of a three-phase electric machine for harvesting energy from vibrations. We consider the use of vector control techniques, which are common in the area of industrial electronics, for optimizing the feedback loops in a stochastically-excited energy harvesting system. To do this, we decompose the problem into two separate feedback loops for direct and quadrature current components, and illustrate how each might be separately optimized to maximize power output. In a simple analytical example, we illustrate how these techniques might be used to gain insight into the tradeoffs in the design of the electronic hardware and the choice of bus voltage.
Evaluating vehicular-induced bridge vibrations for energy harvesting applications
NASA Astrophysics Data System (ADS)
Reichenbach, Matthew; Fasl, Jeremiah; Samaras, Vasilis A.; Wood, Sharon; Helwig, Todd; Lindenberg, Richard
2012-04-01
Highway bridges are vital links in the transportation network in the United States. Identifying possible safety problems in the approximately 600,000 bridges across the country is generally accomplished through labor-intensive, visual inspections. Ongoing research sponsored by NIST seeks to improve inspection practices by providing real-time, continuous monitoring technology for steel bridges. A wireless sensor network with a service life of ten years that is powered by an integrated energy harvester is targeted. In order to achieve the target ten-year life for the monitoring system, novel approaches to energy harvesting for use in recharging batteries are investigated. Three main sources of energy are evaluated: (a) vibrational energy, (b) solar energy, and (c) wind energy. Assessing the energy produced from vehicular-induced vibrations and converted through electromagnetic induction is the focus of this paper. The goal of the study is to process acceleration data and analyze the vibrational response of steel bridges to moving truck loads. Through spectral analysis and harvester modeling, the feasibility of vibration-based energy harvesting for longterm monitoring can be assessed. The effects of bridge conditions, ambient temperature, truck traffic patterns, and harvester position on the power content of the vibrations are investigated. With sensor nodes continually recharged, the proposed real-time monitoring system will operate off the power grid, thus reducing life cycle costs and enhancing inspection practices for state DOTs. This paper will present the results of estimating the vibration energy of a steel bridge in Texas.
Vibration energy harvesting from random force and motion excitations
NASA Astrophysics Data System (ADS)
Tang, Xiudong; Zuo, Lei
2012-07-01
A vibration energy harvester is typically composed of a spring-mass system with an electromagnetic or piezoelectric transducer connected in parallel with a spring. This configuration has been well studied and optimized for harmonic vibration sources. Recently, a dual-mass harvester, where two masses are connected in series by the energy transducer and a spring, has been proposed. The dual-mass vibration energy harvester is proved to be able to harvest more power and has a broader bandwidth than the single-mass configuration, when the parameters are optimized and the excitation is harmonic. In fact, some dual-mass vibration energy harvesters, such as regenerative vehicle suspensions and buildings with regenerative tuned mass dampers (TMDs), are subjected to random excitations. This paper is to investigate the dual-mass and single-mass vibration harvesters under random excitations using spectrum integration and the residue theorem. The output powers for these two types of vibration energy harvesters, when subjected to different random excitations, namely force, displacement, velocity and acceleration, are obtained analytically with closed-form expressions. It is also very interesting to find that the output power of the vibration energy harvesters under random excitations depends on only a few parameters in very simple and elegant forms. This paper also draws some important conclusions on regenerative vehicle suspensions and buildings with regenerative TMDs, which can be modeled as dual-mass vibration energy harvesters. It is found that, under white-noise random velocity excitation from road irregularity, the harvesting power from vehicle suspensions is proportional to the tire stiffness and road vertical excitation spectrum only. It is independent of the chassis mass, tire-wheel mass, suspension stiffness and damping coefficient. Under random wind force excitation, the power harvested from buildings with regenerative TMD will depends on the building mass only, not
Microelectromechanical power generator and vibration sensor
Roesler, Alexander W.; Christenson, Todd R.
2006-11-28
A microelectromechanical (MEM) apparatus is disclosed which can be used to generate electrical power in response to an external source of vibrations, or to sense the vibrations and generate an electrical output voltage in response thereto. The MEM apparatus utilizes a meandering electrical pickup located near a shuttle which holds a plurality of permanent magnets. Upon movement of the shuttle in response to vibrations coupled thereto, the permanent magnets move in a direction substantially parallel to the meandering electrical pickup, and this generates a voltage across the meandering electrical pickup. The MEM apparatus can be fabricated by LIGA or micromachining.
NASA Astrophysics Data System (ADS)
Lu, Y.; O'Riordan, E.; Cottone, F.; Boisseau, S.; Galayko, D.; Blokhina, E.; Marty, F.; Basset, P.
2016-12-01
This paper reports a batch-fabricated, low-frequency and wideband MEMS electrostatic vibration energy harvester (e-VEH), which implements corona-charged vertical electrets and nonlinear elastic stoppers. A numeric model is used to perform parametric study, where we observe a wideband bi-modality resulting from nonlinearity. The nonlinear stoppers improve the bandwidth and induce a frequency-up feature at low frequencies. When the e-VEH works with a bias of 45 V, the power reaches a maximum value of 6.6 μW at 428 Hz and 2.0 g rms, and is above 1 μW at 50 Hz. When the frequency drops below 60 Hz, a ‘frequency-up’ conversion behavior is observed with peaks of power at 34 Hz and 52 Hz. The -3 dB bandwidth is more than 60% of its central frequency, both including and excluding the hysteresis introduced by the nonlinear stoppers. We also perform experiments with wideband Gaussian noise. The device is eventually tested with an RF data transmission setup, where a communication node with an internal temperature sensor is powered. Every 2 min, a data transmission at 868 MHz is performed by the sensor node supplied by the e-VEH, and received at a distance of up to 15 m.
Design, simulation, fabrication, and characterization of MEMS vibration energy harvesters
NASA Astrophysics Data System (ADS)
Oxaal, John
Energy harvesting from ambient sources has been a longtime goal for microsystem engineers. The energy available from ambient sources is substantial and could be used to power wireless micro devices, making them fully autonomous. Self-powered wireless sensors could have many applications in for autonomous monitoring of residential, commercial, industrial, geological, or biological environments. Ambient vibrations are of particular interest for energy harvesting as they are ubiquitous and have ample kinetic energy. In this work a MEMS device for vibration energy harvesting using a variable capacitor structure is presented. The nonlinear electromechanical dynamics of a gap-closing type structure is experimentally studied. Important experimental considerations such as the importance of reducing off-axis vibration during testing, characterization methods, dust contamination, and the effect of grounding on parasitic capacitance are discussed. A comprehensive physics based model is developed and validated with two different microfabricated devices. To achieve maximal power, devices with high aspect ratio electrodes and a novel two-level stopper system are designed and fabricated. The maximum achieved power from the MEMS device when driven by sinusoidal vibrations was 3.38 muW. Vibrations from HVAC air ducts, which have a primary frequency of 65 Hz and amplitude of 155 mgrms, are targeted as the vibration source and devices are designed for maximal power harvesting potential at those conditions. Harvesting from the air ducts, the devices reached 118 nW of power. When normalized to the operating conditions, the best figure of merit of the devices tested was an order of magnitude above state-of-the-art of the devices (1.24E-6).
On Kinetics Modeling of Vibrational Energy Transfer
NASA Technical Reports Server (NTRS)
Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.
Two degrees of freedom piezoelectric vibration energy harvester
NASA Astrophysics Data System (ADS)
Wang, Wei; Liu, Shengsheng; Cao, Junyi; Zhou, Shengxi; Lin, Jing
2016-04-01
Recently, vibration energy harvesting from surrounding environments to power wearable devices and wireless sensors in structure health monitoring has received considerable interest. Piezoelectric conversion mechanism has been employed to develop many successful energy harvesting devices due to its simple structure, long life span, high harvesting efficiency and so on. However, there are many difficulties of microscale cantilever configurations in energy harvesting from low frequency ambient. In order to improve the adaptability of energy harvesting from ambient vibrations, a two degrees of freedom (2-DOF) magnetic-coupled piezoelectric energy harvester is proposed in this paper. The electromechanical governing models of the cantilever and clamped hybrid energy harvester are derived to describe the dynamic characteristics for 2-DOF magnetic-coupled piezoelectric vibration energy harvester. Numerical simulations based on Matlab and ANSYS software show that the proposed magnetically coupled energy harvester can enhance the effective operating frequency bandwidth and increase the energy density. The experimental voltage responses of 2-DOF harvester under different structure parameters are acquired to demonstrate the effectiveness of the lumped parameter model for low frequency excitations. Moreover, the proposed energy harvester can enhance the energy harvesting performance over a wider bandwidth of low frequencies and has a great potential for broadband vibration energy harvesting.
Piezoelectric Power Requirements for Active Vibration Control
NASA Technical Reports Server (NTRS)
Brennan, Matthew C.; McGowan, Anna-Maria Rivas
1997-01-01
This paper presents a method for predicting the power consumption of piezoelectric actuators utilized for active vibration control. Analytical developments and experimental tests show that the maximum power required to control a structure using surface-bonded piezoelectric actuators is independent of the dynamics between the piezoelectric actuator and the host structure. The results demonstrate that for a perfectly-controlled system, the power consumption is a function of the quantity and type of piezoelectric actuators and the voltage and frequency of the control law output signal. Furthermore, as control effectiveness decreases, the power consumption of the piezoelectric actuators decreases. In addition, experimental results revealed a non-linear behavior in the material properties of piezoelectric actuators. The material non- linearity displayed a significant increase in capacitance with an increase in excitation voltage. Tests show that if the non-linearity of the capacitance was accounted for, a conservative estimate of the power can easily be determined.
NASA Astrophysics Data System (ADS)
Lee, Chun-Ying; Lin, Jia-Hong
2017-02-01
Tunable vibration absorber is an effective device to reduce the vibration of structure subjected to harmonic excitation. The vibration energy is transferred mostly to the absorber when the natural frequency of the absorber is tuned to the excitation frequency. In this study, a piezoelectric (PZT) transducer was incorporated into the absorber in order to harvest the vibration energy and still alleviate the vibration of a platform structure. The tuning in dynamic characteristics of the absorber was facilitated by controlling its tip mass. The design formulation of the absorber was presented with a single degree-of-freedom (SDOF) model having the equivalent parameters. In the meantime, an optimal electric load resistor was determined to maximize the power output from the PZT transducer. The experimental measurement validated the SDOF model with good accuracy both in the vibration response and the output electric voltage. Finally, the absorber was installed on a platform structure to investigate its vibration reduction and energy harvesting capability for the external disturbance frequency covering certain frequency span. With three resonance modes of the platform studied, the absorber was able to reduce more than 80% of its original vibration and harvest several folds of electric power comparing with the untuned absorber. Although the performance in vibration reduction was slightly influenced (<6%), the great increase in the electric energy harvested revealed the absorber design a good potential toward self-powered sensor or actuator applications.
Statistics of power input into a vibrated granular system
NASA Astrophysics Data System (ADS)
Wang, Hongqiang; Feitosa, Klebert; Menon, Narayanan
2004-03-01
Statistics of power input into a vibrated granular system Authors: Hongqiang Wang, Klebert Feitosa, Narayanan Menon Motivated by the recent Fluctuation theorem of Gallavotti and Cohen, we demonstrate a numerical and experimental exploration of the fluctuations in power input and energy dissipation in a sub-volume of a vibrated granular system. Both experimental and simulation results are in accord with the Fluctuation relation, even for short-time fluctuations. In the simulations, we are also able to compare power fluctuations in rotational and translational modes; we discuss the effective temperatures arising from this fluctuation relation. Finally, in the simulations, we also study the dependence of our results on the size of the sub-volume considered in the system. Supported by: NSF DMR 9878433, DMR 0216719
Magnetically levitated autoparametric broadband vibration energy harvesting
NASA Astrophysics Data System (ADS)
Kurmann, L.; Jia, Y.; Manoli, Y.; Woias, P.
2016-11-01
Some of the lingering challenges within the current paradigm of vibration energy harvesting (VEH) involve narrow operational frequency range and the inevitable non-resonant response from broadband noise excitations. Such VEHs are only suitable for limited applications with fixed sinusoidal vibration, and fail to capture a large spectrum of the real world vibration. Various arraying designs, frequency tuning schemes and nonlinear vibratory approaches have only yielded modest enhancements. To fundamentally address this, the paper proposes and explores the potentials in using highly nonlinear magnetic spring force to activate an autoparametric oscillator, in order to realize an inherently broadband resonant system. Analytical and numerical modelling illustrate that high spring nonlinearity derived from magnetic levitation helps to promote the 2:1 internal frequency matching required to activate parametric resonance. At the right internal parameters, the resulting system can intrinsically exhibit semi-resonant response regardless of the bandwidth of the input vibration, including broadband white noise excitation.
Vibration Monitoring of Power Distribution Poles
Clark Scott; Gail Heath; John Svoboda
2006-04-01
Some of the most visible and least monitored elements of our national security infrastructure are the poles and towers used for the distribution of our nation’s electrical power. Issues surrounding these elements within the United States include safety such as unauthorized climbing and access, vandalism such as nut/bolt removal or destructive small arms fire, and major vandalism such as the downing of power poles and towers by the cutting of the poles with a chainsaw or torches. The Idaho National Laboratory (INL) has an ongoing research program working to develop inexpensive and sensitive sensor platforms for the monitoring and characterization of damage to the power distribution infrastructure. This presentation covers the results from the instrumentation of a variety of power poles and wires with geophone assemblies and the recording of vibration data when power poles were subjected to a variety of stimuli. Initial results indicate that, for the majority of attacks against power poles, the resulting signal can be seen not only on the targeted pole but on sensors several poles away in the distribution network and a distributed sensor system can be used to monitor remote and critical structures.
Piezoelectric energy harvesting from traffic-induced bridge vibrations
NASA Astrophysics Data System (ADS)
Peigney, Michaël; Siegert, Dominique
2013-09-01
This paper focuses on energy harvesting from traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case study, in situ vibration measurements are presented and analysed. From these results, a prototype of a cantilever piezoelectric harvester is designed, tested and modelled. Even though the considered bridge vibrations are characterized by small amplitude and a low frequency (i.e. below 15 Hz), it is shown that mean power of the order of 0.03 mW can be produced, with a controlled voltage between 1.8 and 3.6 V. A simple model is proposed for theoretical prediction of the delivered power in terms of traffic intensity. This model shows good agreement with the experimental results and leads to a simple but effective design rule for piezoelectric harvesters to be used on bridges.
Vibration energy harvesting using Galfenol-based transducer
NASA Astrophysics Data System (ADS)
Berbyuk, Viktor
2013-04-01
In this paper the novel design of Galfenol based vibration energy harvester is presented. The device uses Galfenol rod diameter 6.35 mm and length 50mm, polycrystalline, production grade, manufactured by FSZM process by ETREMA Product Inc. For experimental study of the harvester, the test rig was developed. It was found by experiment that for given frequency of external excitation there exist optimal values of bias and pre-stress which maximize generated voltage and harvested power. Under optimized operational conditions and external excitations with frequency 50Hz the designed transducer generates about 10 V and harvests about 0,45 W power. Within the running conditions, the Galfenol rod power density was estimated to 340mW/cm3. The obtained results show high practical potential of Galfenol based sensors for vibration-to-electrical energy conversion, structural health monitoring, etc.
Mechanical vibration to electrical energy converter
Kellogg, Rick Allen; Brotz, Jay Kristoffer
2009-03-03
Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.
A new figure of merit for wideband vibration energy harvesters
NASA Astrophysics Data System (ADS)
Liu, W. Q.; Badel, A.; Formosa, F.; Wu, Y. P.
2015-12-01
The performance evaluation method is a very important part in the field of vibration energy harvesting. It provides the ability to compare and rate different vibration energy harvesters (VEHs). Considering the lack of a well-recognized tool, this article proposed a new systematic figure of merit for the appraisement of wideband VEHs. Extensive investigations are first performed for some classic figures for linear VEHs. With the common fundamental information obtained, the proposed figure integrates four essential factors: the revised energy harvester effectiveness, the mechanical quality factor, the normalized bandwidth and the effective mass density. Special considerations are devoted to the properties of wideband VEHs about the operation range and the average power in this domain which are related to the performance target of stable power output. Afterward, this new figure is applied to some literature VEHs and demonstrated to present good evaluations of wideband VEHs. Moreover, it exhibits the ability to point out the improvement information of the concerned VEHs further developments.
Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano; Silvers, Kurt L.
2013-07-01
Formal journal article Experimental analysis of a piezoelectric energy harvesting system for harmonic, random, and sine on random vibration Abstract: Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random and sine on random (SOR) input vibration scenarios. Additionally, the implications of source vibration characteristics on harvester design are discussed. Studies in vibration harvesting have yielded numerous alternatives for harvesting electrical energy from vibrations but piezoceramics arose as the most compact, energy dense means of energy transduction. The rise in popularity of harvesting energy from ambient vibrations has made piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. In this manuscript, variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. We characterize the source vibration by its acceleration response for repeatability and transcription to general application. The results agree with numerical and theoretical predictions for in previous literature that load optimal resistance varies with transducer natural frequency and source type, and the findings demonstrate that significant gains are seen with lower tuned transducer natural frequencies for similar source amplitudes. Going beyond idealized steady state sinusoidal and simplified random vibration input, SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibrational sources significantly alter power generation and power processing
Damping and energy dissipation in soft tissue vibrations during running.
Khassetarash, Arash; Hassannejad, Reza; Enders, Hendrik; Ettefagh, Mir Mohammad
2015-01-21
It has been well accepted that the vibrations of soft tissue cannot be simulated by a single sinusoidal function. In fact, these vibrations are a combination of several vibration modes. In this study, these modes are extracted applying a recently developed method namely, partly ensemble empirical mode decomposition (PEEMD). Then, a methodology for estimating the damping properties and energy dissipation caused by damping for each mode is used. Applying this methodology on simulated signals demonstrates high accuracy. This methodology is applied to the acceleration signals of the gastrocnemius muscle during sprinting and the differences between the damping properties of different vibration modes were identified. The results were 1) the damping property of high-frequency mode was higher than that for low-frequency modes. 2) All identified modes were in under damped condition, therefore, the vibrations had an oscillatory nature. 3) The damping ratios of lower modes are about 100% increased compared to higher modes. 4) The energy dissipation occurred in lower modes were much more than that for higher mode; According to the power spectrum of the ground reaction force (GRF), which is the input force into the body, the recent finding supports the muscle tuning paradigm. It is suggested that the damping properties and energy dissipation can be used to distinguish between different running conditions (surface, fatigue, etc.).
Energy harvesting from an autoparametric vibration absorber
NASA Astrophysics Data System (ADS)
Yan, Zhimiao; Hajj, Muhammad R.
2015-11-01
The combined control and energy harvesting characteristics of an autoparametric vibration absorber consisting of a base structure subjected to the external force and a cantilever beam with a tip mass are investigated. The piezoelectric sheets are attached to the cantilever beam to convert the vibrations of the base structure into electrical energy. The coupled nonlinear representative model is developed by using the extended Hamiton’s principle. The effects of the electrical load resistance on the frequency and damping ratio of the cantilever beam are analyzed. The impacts of the external force and load resistance on the structural displacements of the base structure and the beam and on the level of harvested energy are determined. The results show that the initial conditions have a significant impact on the system’s response. The relatively high level of energy harvesting is not necessarily accompanied with the minimum displacements of the base structure.
Efficiency enhancement of a cantilever-based vibration energy harvester.
Kubba, Ali E; Jiang, Kyle
2013-12-23
Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (V(ave)), and average normal strain in the piezoelectric transducer (ε(ave)) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle).
Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester
Kubba, Ali E.; Jiang, Kyle
2014-01-01
Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (Vave), and average normal strain in the piezoelectric transducer (εave) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle). PMID:24366177
Vibrational energy transport in the presence of intrasite vibrational energy redistribution.
Schade, Marco; Hamm, Peter
2009-07-28
The mechanism of vibrational energy flow is studied in a regime where a diffusion equation is likely to break down, i.e., on length scales of a few chemical bonds and time scales of a few picoseconds. This situation occurs, for example, during photochemical reactions in protein environment. To that end, a toy model is introduced that on the one hand mimics the vibrational normal mode distribution of proteins, and on the other hand is small enough to numerically time propagate the system fully quantum mechanically. Comparing classical and quantum-mechanical results, the question is addressed to what extent the classical nature of the molecular dynamics simulations (which would be the only choice for the modeling of a real molecular system) affects the vibrational energy flow mechanism. Small differences are found which are due to the different ways classical and quantum mechanics distribute thermal energy over vibrational modes. In either case, a ballistic and a diffusive phase can be identified. For these small length and time scales, the latter is governed by intrasite vibrational energy redistribution, since vibrational energy does not necessarily thermalize completely within individual peptide units. Overall, the model suggests a picture that unifies many of the observations made recently in experiments.
Electrostatic MEMS vibration energy harvester for HVAC applications
NASA Astrophysics Data System (ADS)
Oxaal, J.; Hella, M.; Borca-Tasciuc, D.-A.
2015-12-01
This paper reports on an electrostatic MEMS vibration energy harvester with gapclosing interdigitated electrodes, designed for and tested on HVAC air ducts. The device is fabricated on SOI wafers using a custom microfabrication process. A dual-level physical stopper system is implemented in order to control the minimum gap between the electrodes and maximize the power output. It utilizes cantilever beams to absorb a portion of the impact energy as the electrodes approach the impact point, and a film of parylene with nanometer thickness deposited on the electrode sidewalls, which defines the absolute minimum gap and provides electrical insulation. The fabricated device was first tested on a vibration shaker to characterize its resonant behavior. The device exhibits spring hardening behavior due to impacts with the stoppers and spring softening behavior with increasing voltage bias. Testing was carried out on HVAC air duct vibrating with an RMS acceleration of 155 mgRMS and a primary frequency of 60 Hz with a PSD of 7.15·10-2 g2/Hz. The peak power measured is 12nW (0.6 nW RMS) with a PSD of 6.9·10-11 W/Hz at 240 Hz (four times of the primary frequency of 60 Hz), which is the highest output reported for similar vibration conditions and biasing voltages.
Multistable chain for ocean wave vibration energy harvesting
NASA Astrophysics Data System (ADS)
Harne, R. L.; Schoemaker, M. E.; Wang, K. W.
2014-03-01
The heaving of ocean waves is a largely untapped, renewable kinetic energy resource. Conversion of this energy into electrical power could integrate with solar technologies to provide for round-the-clock, portable, and mobile energy supplies usable in a wide variety of marine environments. However, the direct drive conversion methodology of gridintegrated wave energy converters does not efficiently scale down to smaller, portable architectures. This research develops an alternative power conversion approach to harness the extraordinarily large heaving displacements and long oscillation periods as an excitation source for an extendible vibration energy harvesting chain. Building upon related research findings and engineering insights, the proposed system joins together a series of dynamic cells through bistable interfaces. Individual impulse events are generated as the inertial mass of each cell is pulled across a region of negative stiffness to induce local snap through dynamics; the oscillating magnetic inertial mass then generates current in a coil which is connected to energy harvesting circuitry. It is shown that linking the cells into a chain transmits impulses through the system leading to cascades of vibration and enhancement of electrical energy conversion from each impulse event. This paper describes the development of the multistable chain and ways in which realistic design challenges were addressed. Numerical modeling and corresponding experiments demonstrate the response of the chain due to slow and large amplitude input motion. Lastly, experimental studies give evidence that energy conversion efficiency of the chain for wave energy conversion is much higher than using an equal number of cells without connections.
Ueno, Toshiyuki
2015-05-07
Vibration based power generation technology is utilized effectively in various fields. Author has invented novel vibrational power generation device using magnetostrictive material. The device is based on parallel beam structure consisting of a rod of iron-gallium alloy wound with coil and yoke accompanied with permanent magnet. When bending force is applied on the tip of the device, the magnetization inside the rod varies with induced stress due to the inverse magnetostrictive effect. In vibration, the time variation of the magnetization generates voltage on the wound coil. The magnetostrictive type is advantageous over conventional such using piezoelectric or moving magnet types in high efficiency and high robustness, and low electrical impedance. Here, author has established device configuration, simple, rigid, and high power output endurable for practical applications. In addition, the improved device is lower cost using less volume of Fe-Ga and permanent magnet compared to our conventional, and its assembly by soldering is easy and fast suitable for mass production. Average power of 3 mW/cm{sup 3} under resonant vibration of 212 Hz and 1.2 G was obtained in miniature prototype using Fe-Ga rod of 2 × 0.5× 7 mm{sup 3}. Furthermore, the damping effect was observed, which demonstrates high energy conversion of the generator.
Vibration power generator for a linear MR damper
NASA Astrophysics Data System (ADS)
Sapiński, Bogdan
2010-10-01
The paper describes the structure and the results of numerical calculations and experimental tests of a newly developed vibration power generator for a linear magnetorheological (MR) damper. The generator consists of permanent magnets and coil with foil winding. The device produces electrical energy according to Faraday's law of electromagnetic induction. This energy is applied to vary the damping characteristics of the MR damper attached to the generator by the input current produced by the device. The objective of the numerical calculations was to determine the magnetic field distribution in the generator as well as the electric potential and current density in the generator's coil during the idle run and under the load applied to the MR damper control coil. The results of the calculations were used during the design and manufacturing stages of the device. The objective of the experimental tests carried out on a dynamic testing machine was to evaluate the generator's efficiency and to compare the experimental and predicted data. The experimental results demonstrate that the engineered device enables a change in the kinetic energy of the reciprocal motion of the MR damper which leads to variations in the damping characteristics. That is why the generator may be used to build up MR damper based vibration control systems which require no external power.
Energy harvester array using piezoelectric circular diaphragm for rail vibration
NASA Astrophysics Data System (ADS)
Wang, Wei; Huang, Rong-Jin; Huang, Chuan-Jun; Li, Lai-Feng
2014-12-01
Generating electric energy from mechanical vibration using a piezoelectric circular membrane array is presented in this paper. The electrical characteristics of the functional array consisted of three plates with varies tip masses are examined under dynamic conditions. With an optimal load resistor of 11 kΩ, an output power of 21.4 mW was generated from the array in parallel connection at 150 Hz under a pre-stress of 0.8 N and a vibration acceleration of 9.8 m/s2. Moreover, the broadband energy harvesting using this array still can be realized with different tip masses. Three obvious output power peaks can be obtained in a frequency spectra of 110 Hz to 260 Hz. The results show that using a piezoelectric circular diaphragm array can increase significantly the output of energy compared with the use of a single plate. And by optimizing combination of tip masses with piezoelectric elements in array, the frequency range can be tuned to meet the broadband vibration. This array may possibly be exploited to design the energy harvesting for practical applications such as future high speed rail.
Magnetostrictive vibration damper and energy harvester for rotating machinery
NASA Astrophysics Data System (ADS)
Deng, Zhangxian; Asnani, Vivake M.; Dapino, Marcelo J.
2015-04-01
Vibrations generated by machine driveline components can cause excessive noise and structural dam- age. Magnetostrictive materials, including Galfenol (iron-gallium alloys) and Terfenol-D (terbium-iron- dysprosium alloys), are able to convert mechanical energy to magnetic energy. A magnetostrictive vibration ring is proposed, which generates electrical energy and dampens vibration, when installed in a machine driveline. A 2D axisymmetric finite element (FE) model incorporating magnetic, mechanical, and electrical dynamics is constructed in COMSOL Multiphysics. Based on the model, a parametric study considering magnetostrictive material geometry, pickup coil size, bias magnet strength, flux path design, and electrical load is conducted to maximize loss factor and average electrical output power. By connecting various resistive loads to the pickup coil, the maximum loss factors for Galfenol and Terfenol-D due to electrical energy loss are identified as 0.14 and 0.34, respectively. The maximum av- erage electrical output power for Galfenol and Terfenol-D is 0.21 W and 0.58 W, respectively. The loss factors for Galfenol and Terfenol-D are increased to 0.59 and 1.83, respectively, by using an L-C resonant circuit.
Magnetostrictive Vibration Damper and Energy Harvester for Rotating Machinery
NASA Technical Reports Server (NTRS)
Deng, Zhangxian; Asnani, Vivake M.; Dapino, Marcelo J.
2015-01-01
Vibrations generated by machine driveline components can cause excessive noise and structural damage. Magnetostrictive materials, including Galfenol (iron-gallium alloys) and Terfenol-D (terbium-iron-dysprosium alloys), are able to convert mechanical energy to magnetic energy. A magnetostrictive vibration ring is proposed, which generates electrical energy and dampens vibration, when installed in a machine driveline. A 2D axisymmetric finite element (FE) model incorporating magnetic, mechanical, and electrical dynamics is constructed in COMSOL Multiphysics. Based on the model, a parametric study considering magnetostrictive material geometry, pickup coil size, bias magnet strength, flux path design, and electrical load is conducted to maximize loss factor and average electrical output power. By connecting various resistive loads to the pickup coil, the maximum loss factors for Galfenol and Terfenol-D due to electrical energy loss are identified as 0.14 and 0.34, respectively. The maximum average electrical output power for Galfenol and Terfenol-D is 0.21 W and 0.58 W, respectively. The loss factors for Galfenol and Terfenol-D are increased to 0.59 and 1.83, respectively, by using an L-C resonant circuit.
Harvesting energy from the natural vibration of human walking.
Yang, Weiqing; Chen, Jun; Zhu, Guang; Yang, Jin; Bai, Peng; Su, Yuanjie; Jing, Qingsheng; Cao, Xia; Wang, Zhong Lin
2013-12-23
The triboelectric nanogenerator (TENG), a unique technology for harvesting ambient mechanical energy based on the triboelectric effect, has been proven to be a cost-effective, simple, and robust approach for self-powered systems. However, a general challenge is that the output current is usually low. Here, we demonstrated a rationally designed TENG with integrated rhombic gridding, which greatly improved the total current output owing to the structurally multiplied unit cells connected in parallel. With the hybridization of both the contact-separation mode and sliding electrification mode among nanowire arrays and nanopores fabricated onto the surfaces of two contact plates, the newly designed TENG produces an open-circuit voltage up to 428 V, and a short-circuit current of 1.395 mA with the peak power density of 30.7 W/m(2). Relying on the TENG, a self-powered backpack was developed with a vibration-to-electric energy conversion efficiency up to 10.62(±1.19) %. And it was also demonstrated as a direct power source for instantaneously lighting 40 commercial light-emitting diodes by harvesting the vibration energy from natural human walking. The newly designed TENG can be a mobile power source for field engineers, explorers, and disaster-relief workers.
Fundamental issues in nonlinear wideband-vibration energy harvesting
NASA Astrophysics Data System (ADS)
Halvorsen, Einar
2013-04-01
Mechanically nonlinear energy harvesters driven by broadband vibrations modeled as white noise are investigated. We derive an upper bound on output power versus load resistance and show that, subject to mild restrictions that we make precise, the upper-bound performance can be obtained by a linear harvester with appropriate stiffness. Despite this, nonlinear harvesters can have implementation-related advantages. Based on the Kramers equation, we numerically obtain the output power at weak coupling for a selection of phenomenological elastic potentials and discuss their merits.
Resonant vibrational energy transfer in ice Ih.
Shi, L; Li, F; Skinner, J L
2014-06-28
Fascinating anisotropy decay experiments have recently been performed on H2O ice Ih by Timmer and Bakker [R. L. A. Timmer, and H. J. Bakker, J. Phys. Chem. A 114, 4148 (2010)]. The very fast decay (on the order of 100 fs) is indicative of resonant energy transfer between OH stretches on different molecules. Isotope dilution experiments with deuterium show a dramatic dependence on the hydrogen mole fraction, which confirms the energy transfer picture. Timmer and Bakker have interpreted the experiments with a Förster incoherent hopping model, finding that energy transfer within the first solvation shell dominates the relaxation process. We have developed a microscopic theory of vibrational spectroscopy of water and ice, and herein we use this theory to calculate the anisotropy decay in ice as a function of hydrogen mole fraction. We obtain very good agreement with experiment. Interpretation of our results shows that four nearest-neighbor acceptors dominate the energy transfer, and that while the incoherent hopping picture is qualitatively correct, vibrational energy transport is partially coherent on the relevant timescale.
Low Frequency Vibration Energy Harvesting using Diamagnetically Stabilized Magnet Levitation
NASA Astrophysics Data System (ADS)
Palagummi, Sri Vikram
Over the last decade, vibration-based energy harvesting has provided a technology push on the feasibility of self-powered portable small electronic devices and wireless sensor nodes. Vibration energy harvesters in general transduce energy by damping out the environmentally induced relative emotion through either a cantilever beam or an equivalent suspension mechanism with one of the transduction mechanisms, like, piezoelectric, electrostatic, electromagnetic or magnetostrictive. Two major challenges face the present harvesters in literature, one, they suffer from the unavoidable mechanical damping due to internal friction present in the systems, second, they cannot operate efficiently in the low frequency range (< 10 Hz), when most of the ambient vibrational energy is in this low frequency broadband range. Passive and friction free diamagnetically stabilized magnet levitation mechanisms which can work efficiently as a vibration energy harvester in the low frequency range are discussed in this work. First, a mono-stable vertical diamagnetic levitation (VDL) based vibration energy harvester (VEH) is discussed. The harvester consists of a lifting magnet (LM), a floating magnet (FM) and two diamagnetic plates (DPs). The LM balances out the weight of the FM and stability is brought about by the repulsive effect of the DPs, made of pyrolytic graphite. Two thick cylindrical coils, placed in grooves which are engraved in the DPs, are used to convert the mechanical energy into electrical energy. Experimental frequency response of the system is validated by the theoretical analysis which showed that the VEH works in a low frequency range but sufficient levitation gap was not achieved and the frequency response characteristic of the system was effectively linear. To overcome these challenges, the influence of the geometry of the FM, the LM, and the DP were parametrically studied to assess their effects on the levitation gap, size of the system and the natural frequency. For
Piezoelectric energy harvesting from heartbeat vibrations for leadless pacemakers
NASA Astrophysics Data System (ADS)
Ansari, M. H.; Karami, M. Amin
2015-12-01
This paper studies energy harvesting from heartbeat vibrations using fan-folded piezoelectric beams. The generated energy from the heartbeat can be used to power a leadless pacemaker. In order to utilize the available 3 dimensional space to the energy harvester, we chose the fan-folded design. The proposed device consists of several piezoelectric beams stacked on top of each other. The size for this energy harvester is 2 cm by 0.5 cm by 1 cm, which makes the natural frequency very high. High natural frequency is one major concern about the micro-scaled energy harvesters. By utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, this natural frequency is reduced to the desired range. This fan-folded design makes it possible to generate more than 10 μW of power. The proposed device does not incorporate magnets and is thus Magnetic resonance imaging (MRI) compatible. Although our device is a linear energy harvester, it is shown that the device is relatively insensitive to the heartrate. The natural frequencies and the mode shapes of the device are calculated. An analytical solution is presented and the method is verified by experimental investigation. We use a closed loop shaker controller and a shaker to simulate the heartbeat vibrations. The developed analytical model is verified through comparison of theoretical and experimental tip displacement and acceleration frequency response functions.
Next Generation Power and Energy
2010-12-02
Cells Advanced Generators Direct Conversion Photovoltaics Future Fuels Energy Storage Batteries Capacitors Flywheels Motors & Actuators Motors Actuators...Generation Power Distribution Energy Storage Power Conversion Propulsion Ship’s Power Sources Mission Systems Industry Competes for Components; ‘Submit...Chiller Technologies / HVAC ONR Maintaining Robust S&T Investment Power LoadSystem Control Power Generation Power Distribution Energy Storage Power
NASA Astrophysics Data System (ADS)
Umaba, M.; Nakamachi, E.; Morita, Y.
2015-12-01
In this study, a high frequency piezoelectric energy harvester converted from the human low vibrated motion energy was newly developed. This hybrid energy harvester consists of the unimorph piezoelectric cantilever, the pendulum and a pair of permanent magnets. One magnet was attached at the edge of cantilever, and the counterpart magnet at the edge of pendulum. The mechanical energy provided through the human walking motion, which is a typical ubiquitous existence of vibration, is converted to the electric energy via the piezoelectric unimorph cantilever vibration. At first, we studied the energy convert mechanism and analyze the performance of novel energy harvester, where the resonance free vibration of unimorph piezoelectric cantilever generated a high electric power. Next, we equipped the counterpart permanent magnet at the edge of pendulum, which vibrates with a very low frequency caused by the human walking. Then the counterpart magnet was set at the edge of unimorph piezoelectric cantilever, which vibrated with a high frequency. This low-to-high frequency convert "dual vibration system" can be characterized as an enhanced energy harvester. We examined and obtained average values of voltage and power in this system, as 8.31 mV and 0.33 μW. Those results show the possibility to apply for the energy harvester in the portable and implantable Bio-MEMS devices.
Vibrational Power Flow in the Moving Belt Passing Through a Tensioner
NASA Astrophysics Data System (ADS)
KWON, Y. I.; IH, J.-G.
2000-01-01
Because of the high performance and low weight requirements for modern machines including engines, the belts servicing high dynamic loads at high speed tend to be very susceptible to the transferred vibration. In this paper, a method is proposed for obtaining the physical characteristics of the transverse vibrational power flow through moving rubber belts. The governing equation is derived by applying Hamilton's principle to the description of the flexural vibrations in axially moving belts, where the tensioner is considered to be a one-degree-of-freedom system. The total power flow calculated and measured in the moving belt is the sum of the true power flow and the power component associated with the steady medium motion. Consequently, any component that is due solely to the belt movement should be subtracted from the total power flow in order to obtain the true, net power flow. This concept is employed in calculating the transverse vibrational power flow through belt-pulley systems that include a tensioner. An equivalent system including an idler instead of the tensioner is also considered, and the observed power flow in this condition is ascribed to the power flow due only to the movement of the medium. The results of analysis show that the vibrational power of the two belt-spans flows into the tensioner. It is shown that the energy flow, measured by using two laser sensors, agrees reasonably well with the predicted results.
Stacked and folded piezoelectrets for vibration-based energy harvesting
NASA Astrophysics Data System (ADS)
Sessler, G. M.; Pondrom, P.; Zhang, X.
2016-08-01
Vibration-based energy harvesting with piezoelectrets can be significantly improved by using multiple layers of these materials. In particular, folding or stacking of piezoelectrets or a combination of these methods results in increased power output of the energy harvesters. The possibilities of these procedures are explored, together with the effect of seismic mass, resonance frequency, and terminating resistance. It is found that with seismic masses of about 20 g and using radiation-crosslinked polypropylene (IXPP) as a piezoelectret, power outputs of up to 80 µW can be achieved for an acceleration of 1 g. Expected dependencies of generated power on frequency, folding and stacking parameters, in particular number of layers, and on seismic mass, are confirmed.
Wideband, low-frequency springless vibration energy harvesters: part I
NASA Astrophysics Data System (ADS)
Bendame, Mohamed; Abdel-Rahman, Eihab; Soliman, Mostafa
2016-11-01
We present a novel architecture for wideband and low-frequency vibration energy harvesting (VEH). Springless vibration energy harvesters (SVEH) employ impact oscillators as energy harvesting elements. A seismic mass moves along a linear guide limited by stoppers at both ends of the track. An electromagnetic transducer converts the kinetic energy captured by the mass into electrical energy. Experiments using prototypes of the horizontal SVEH demonstrated low frequency harvesting (<20 Hz), wideband harvesting (up to 6.0 Hz), and an optimal rectified output power of P = 12 mW for a base acceleration amplitude of 0.5 g. A model of the electromagnetic SVEH was developed and validated experimentally. A figure of merit was defined to quantify realizable output power in linear and nonlinear VEHs. Comparison using this figure of merit shows that electromagnetic SVEHs outperform their linear counterparts by 92%-232% for acceleration amplitudes in the range of 0.4-0.6 g.
NASA Astrophysics Data System (ADS)
Hale, Cameron Edward
Current theories of hegemony have, for the most part, ignored energy as a factor. It is argued here, however, that there are three reasons to expect energy to be a factor in the rise of nations to hegemonic power. First, societies require flow-throughs of energy, material, and information in order to maintain themselves, grow, and develop. Second, the types of energy systems used by a society set somewhat predictable limits on what humans can do and on how they will be organized. And third, since different energy sources and their associated technologies exhibit different capabilities and limitations, advantages may be conferred on one society over another based on the energy sources used by those societies. Case studies of the economic, military, and energy systems of the four nations that have achieved hegemony---Portugal, the Netherlands, the United Kingdom, and the United States---found that changes in energy systems were a significant factor in each instance of hegemony. Also examined was the premise that the rise and decline of hegemonic powers may reflect the movement away from, and subsequent return to, a condition of steady-state---where a society's energy systems, and those parts of the society that respond to changes in energy factors, change very slowly over time. It was postulated that an extended period of stable energy conditions in conjunction with the diffusion of technology would erode any energy-based differences in power among nations. While, on the other hand, the movement away from a condition of steady-state brought on by changes in a society's energy systems might provide that society with enough advantages that it could seek hegemony. Evidence for an association between the movement from one steady-state to another and the rise and decline of hegemony was found in only two of the four cases.
Identification of the nonlinear vibration system of power transformers
NASA Astrophysics Data System (ADS)
Jing, Zheng; Hai, Huang; Pan, Jie; Yanni, Zhang
2017-01-01
This paper focuses on the identification of the nonlinear vibration system of power transformers. A Hammerstein model is used to identify the system with electrical inputs and the vibration of the transformer tank as the output. The nonlinear property of the system is modelled using a Fourier neural network consisting of a nonlinear element and a linear dynamic block. The order and weights of the network are determined based on the Lipschitz criterion and the back-propagation algorithm. This system identification method is tested on several power transformers. Promising results for predicting the transformer vibration and extracting system parameters are presented and discussed.
U-shape magnetostrictive vibration based power generator for universal use
NASA Astrophysics Data System (ADS)
Ueno, T.
2016-04-01
Vibrational power generator extracts electrical energy from ambient vibration. Author invented novel configuration using magnetostrictive material. The device is based on parallel beams of iron-gallium alloy and magnetic material, and features high efficiency, high robustness, and low electrical impedance. In this paper, author proposes U-shape generator for universal use. It consists of the parallel beams and fixed and free end beams forming U-shape frame flexibly modified for variety of mechanical input. Miniature U-shape prototype using Fe-Ga rod 6 by 0.5 by 13 mm3 exhibited average power of 3.7 mW under vibration of 166 Hz and 2.5 G. L-shape type was demonstrated to generate electromotive force by two directional vibrations. In switch type, maximum energy of 0.7 mJ was retrieved by one pushing force. The performances are sufficient to drive wireless module for heath monitoring and remote control.
Vibrational energy levels of CH5+
NASA Astrophysics Data System (ADS)
Wang, Xiao-Gang; Carrington, Tucker
2008-12-01
We present a parallelized contracted basis-iterative method for calculating numerically exact vibrational energy levels of CH5+ (a 12-dimensional calculation). We use Radau polyspherical coordinates and basis functions that are products of eigenfunctions of bend and stretch Hamiltonians. The bend eigenfunctions are computed in a nondirect product basis with more than 200×106 functions and the stretch functions are computed in a product potential optimized discrete variable basis. The basis functions have amplitude in all of the 120 equivalent minima. Many low-lying levels are well converged. We find that the energy level pattern is determined in part by the curvature and width of the valley connecting the minima and in part by the slope of the walls of this valley but does not depend on the height or shape of the barriers separating the minima.
Production, Delivery and Application of Vibration Energy in Healthcare
NASA Astrophysics Data System (ADS)
Abundo, Paolo; Trombetta, Chiara; Foti, Calogero; Rosato, Nicola
2011-02-01
In Rehabilitation Medicine therapeutic application of vibration energy in specific clinical treatments and in sport rehabilitation is being affirmed more and more.Vibration exposure can have positive or negative effects on the human body depending on the features and time of the characterizing wave. The human body is constantly subjected to different kinds of vibrations, inducing bones and muscles to actively modify their structure and metabolism in order to fulfill the required functions. Like every other machine, the body supports only certain vibration energy levels over which long term impairments can be recognized. As shown in literature anyway, short periods of vibration exposure and specific frequency values can determine positive adjustments.
Methods of performing downhole operations using orbital vibrator energy sources
Cole, Jack H.; Weinberg, David M.; Wilson, Dennis R.
2004-02-17
Methods of performing down hole operations in a wellbore. A vibrational source is positioned within a tubular member such that an annulus is formed between the vibrational source and an interior surface of the tubular member. A fluid medium, such as high bulk modulus drilling mud, is disposed within the annulus. The vibrational source forms a fluid coupling with the tubular member through the fluid medium to transfer vibrational energy to the tubular member. The vibrational energy may be used, for example, to free a stuck tubular, consolidate a cement slurry and/or detect voids within a cement slurry prior to the curing thereof.
Airflow energy harvesters of metal-based PZT thin films by self-excited vibration
NASA Astrophysics Data System (ADS)
Suwa, E.; Tsujiura, Y.; Kurokawa, F.; Hida, H.; Kanno, I.
2014-11-01
We developed self-excited vibration energy harvesters of Pb(Zr,Ti)O3 (PZT) thin films using airflow. To enhance the self-excited vibration, we used 30-μm-thick stainless steel (SS304) foils as base cantilevers on which PZT thin films were deposited by rf-magnetron sputtering. To compensate for the initial bending of PZT/SS304 unimorph cantilever due to the thermal stress, we deposited counter PZT thin films on the back of the SS304 cantilever. We evaluated power-generation performance and vibration mode of the energy harvester in the airflow. When the angle of attack (AOA) was 20° to 30°, large vibration was generated at wind speeds over 8 m/s. By FFT analysis, we confirmed that stable self-excited vibration was generated. At the AOA of 30°, the output power reached 19 μW at wind speeds of 12 m/s.
Dark Energy Drives Vibrating Atoms, Chain reactions, Etc.:
NASA Astrophysics Data System (ADS)
Sven, Charles
2010-03-01
The 14 billion year old atom - destroyed Hiroshima, vibrates at a 100 trillion times/sec, emanates photons at the speed of light, contains atom sized proton force field that attracts electrons, all driven by ``Dark Energy.'' This ageless atom's superpowerful requirements, must be supplied from a huge, external, super high-frequency, super-cooled, ``Dark Energy field,'' undetected by current technology, existing for 14+ billion years without degradation. Demonstrating this age-old atom's ``dark energy'' power source requires the synthesis of a number of elements, forces, observations and experiments, many of which are combined in novel but only in replicable venues. Solution includes ``Dark Energy'' participation in celestial observations. Expanded excerpt from my presentation at: the American Physical Society's April meeting in Denver 2009 Section T8: Cosmology
Energy harvesting from structural vibrations of magnetic shape memory alloys
NASA Astrophysics Data System (ADS)
Farsangi, Mohammad Amin Askari; Cottone, Francesco; Sayyaadi, Hassan; Zakerzadeh, Mohammad Reza; Orfei, Francesco; Gammaitoni, Luca
2017-03-01
This letter presents the idea of scavenging energy from vibrating structures through magnetic shape memory alloy (MSMA). To this end, a MSMA specimen made of Ni50Mn28Ga22 is coupled to a cantilever beam through a step. Two permanent magnets installed at the top and bottom of the beam create a bias field perpendicular to the magnetization axis of the specimen. When vibrating the device, a longitudinal axial load applies on the MSMA, which in turn changes the magnetization, due to the martensitic variant reorientation mechanism. A pick-up coil wounded around the MSMA converts this variation into voltage according to the Faraday's law. Experimental test confirms the possibility of generating voltage in a vibrating MSMA. In particular, 15 μW power is harvested for acceleration of 0.3 g RMS at a frequency of 19.1 Hz, which is comparable with piezoelectric energy harvesters. It is also found that the optimum bias magnetic field for maximum voltage is lower than the starting field of pseudo elastic behavior.
Vibration-based energy harvesting with stacked piezoelectrets
Pondrom, P.; Hillenbrand, J.; Sessler, G. M.; Bös, J.; Melz, T.
2014-04-28
Vibration-based energy harvesters with multi-layer piezoelectrets (ferroelectrets) are presented. Using a simple setup with nine layers and a seismic mass of 8 g, it is possible to generate a power up to 1.3 µW at 140 Hz with an input acceleration of 1g. With better coupling between seismic mass and piezoelectret, and thus reduced damping, the power output of a single-layer system is increased to 5 µW at 700 Hz. Simulations indicate that for such improved setups with 10-layer stacks, utilizing seismic masses of 80 g, power levels of 0.1 to 1 mW can be expected below 100 Hz.
Smart nanocoated structure for energy harvesting at low frequency vibration
NASA Astrophysics Data System (ADS)
Sharma, Sudhanshu
Increasing demands of energy which is cleaner and has an unlimited supply has led development in the field of energy harvesting. Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, piezoelectric power generation can provide a convenient alternative to traditional power sources. In this research, a piezoelectric power generator composite prototype was developed to maximize the power output of the system. A lead zirconate titanate (PZT) composite structure was formed and mounted on a cantilever bar and was studied to convert vibration energy of the low range vibrations at 30 Hz--1000 Hz. To improve the performance of the PZT, different coatings were made using different percentage of Ferrofluid (FNP) and Zinc Oxide nanoparticles (ZnO) and binder resin. The optimal coating mixture constituent percentage was based on the performance of the composite structure formed by applying the coating on the PZT. The fabricated PZT power generator composite with an effective volume of 0.062 cm3 produced a maximum of 44.5 μW, or 0.717mW/cm3 at its resonant frequency of 90 Hz. The optimal coating mixture had the composition of 59.9%FNP + 40% ZnO + 1% Resin Binder. The coating utilizes the opto-magneto-electrical properties of ZnO and Magnetic properties of FNP. To further enhance the output, the magneto-electric (ME) effect was increased by subjecting the composite to magnetic field where coating acts as a magnetostrictive material. For the effective volume of 0.0062 cm 3, the composite produced a maximum of 68.5 μW, or 1.11mW/cm 3 at its resonant frequency of 90 Hz at 160 gauss. The optimal coating mixture had the composition of 59.9% FNP + 40% ZnO + 1% Resin Binder. This research also focused on improving the efficiency of solar cells by utilizing the magnetic effect along with gas plasma etching to improve the internal reflection
An implantable fluidic vibrational energy harvester
NASA Astrophysics Data System (ADS)
Inoue, S.; Takahashi, T.; Kumemura, M.; Fujita, H.; Toshiyoshi, H.
2016-11-01
Targeting implantable medical devices such as respiratory pace-maker, we have developed a proof-of-concept level energy harvester device that could earn electric power of 44 μW/cm2 by the fluidic motion in a PDMS microchannel placed on a silicon substrate with built-in permanent electrical charges or so-called electrets. The motion of the working fluid will be operated by the heart beat or breathing as a final shape of the energy harvesting system.
Vibration-assisted resonance in photosynthetic excitation-energy transfer
NASA Astrophysics Data System (ADS)
Irish, E. K.; Gómez-Bombarelli, R.; Lovett, B. W.
2014-07-01
Understanding how the effectiveness of natural photosynthetic energy-harvesting systems arises from the interplay between quantum coherence and environmental noise represents a significant challenge for quantum theory. Recently it has begun to be appreciated that discrete molecular vibrational modes may play an important role in the dynamics of such systems. Here we present a microscopic mechanism by which intramolecular vibrations may be able to contribute to the efficiency and directionality of energy transfer. Excited vibrational states create resonant pathways through the system, supporting fast and efficient energy transport. Vibrational damping together with the natural downhill arrangement of molecular energy levels gives intrinsic directionality to the energy flow. Analytical and numerical results demonstrate a significant enhancement of the efficiency and directionality of energy transport that can be directly related to the existence of resonances between vibrational and excitonic levels.
Membrane-type vibrational energy harvester based on a multi-layered piezoelectric membrane
NASA Astrophysics Data System (ADS)
Yoo, Seunghwan; Kim, Jonghun; Park, Suk-in; Jang, Cheol-Yong; Jeong, Hakgeun
2014-03-01
In this study, we fabricated a membrane-type vibrational energy harvester by using a conventional micro-electro-mechanical (MEMS) method. The membrane-type vibrational energy harvester consists of a multi-layered diaphragm for stable and flexible vibration, a piezoelectric ZnO film for responding to the vibrational energy and for generating electric power, and a vibrator connected to the bottom of multi-layered diaphragm for enhancing the vibrational displacement of the diaphragm. First, we characterized the quality of a ZnO film through scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD), which showed a preferred c-axis orientation, a hexagonal rod shape and a quite smooth surface. After the membrane-type vibrational energy harvester had been fabricated, we integrated it into a printing circuit board to realize piezoelectric generation and confirm its performance. Finally, under vibrational motion, we obtained a useful output voltage of 400 mV, and we estimated that the energy harvester generated an actual output voltage of about 200 uV.
NASA Astrophysics Data System (ADS)
Zalesskaya, G. A.; Yakovlev, D. L.; Sambor, E. G.
2000-08-01
Efficiency of vibrational energy transfer (VET) in vibrational quasicontinuum of triplet states was estimated from the dependence of time-resolved delayed fluorescence of benzophenone and anthraquinone on bath gas pressure. The negative temperature dependence for vibration-vibration (V-V) and positive for vibration-translation (V-T) energy transfers from benzophenone and anthraquinone to bath gases (C 2H 4, SF 6, CCl 4, C 5H 12) were obtained between 373 and 553 K. Polarizability and dipole moment of colliding molecules seem to affect the efficiency of V-V relaxation. These data reflect the dominance of long-range attractive interactions in V-V energy transfer and short-range repulsive interactions in V-T energy transfer.
Vibrational energy transfer in shocked molecular crystals.
Hooper, Joe
2010-01-07
We consider the process of establishing thermal equilibrium behind an ideal shock front in molecular crystals and its possible role in initiating chemical reaction at high shock pressures. A new theory of equilibration via multiphonon energy transfer is developed to treat the scattering of shock-induced phonons into internal molecular vibrations. Simple analytic forms are derived for the change in this energy transfer at different Hugoniot end states following shock compression. The total time required for thermal equilibration is found to be an order of magnitude or faster than proposed in previous work; in materials representative of explosive molecular crystals, equilibration is predicted to occur within a few picoseconds following the passage of an ideal shock wave. Recent molecular dynamics calculations are consistent with these time scales. The possibility of defect-induced temperature localization due purely to nonequilibrium phonon processes is studied by means of a simple model of the strain field around an inhomogeneity. The specific case of immobile straight dislocations is studied, and a region of enhanced energy transfer on the order of 5 nm is found. Due to the rapid establishment of thermal equilibrium, these regions are unrelated to the shock sensitivity of a material but may allow temperature localization at high shock pressures. Results also suggest that if any decomposition due to molecular collisions is occurring within the shock front itself, these collisions are not enhanced by any nonequilibrium thermal state.
A hybrid indoor ambient light and vibration energy harvester for wireless sensor nodes.
Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei
2014-05-19
To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT) for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si) solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%.
A Hybrid Indoor Ambient Light and Vibration Energy Harvester for Wireless Sensor Nodes
Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei
2014-01-01
To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT) for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si) solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%. PMID:24854054
A 3D printed electromagnetic nonlinear vibration energy harvester
NASA Astrophysics Data System (ADS)
Constantinou, P.; Roy, S.
2016-09-01
A 3D printed electromagnetic vibration energy harvester is presented. The motion of the device is in-plane with the excitation vibrations, and this is enabled through the exploitation of a leaf isosceles trapezoidal flexural pivot topology. This topology is ideally suited for systems requiring restricted out-of-plane motion and benefits from being fabricated monolithically. This is achieved by 3D printing the topology with materials having a low flexural modulus. The presented system has a nonlinear softening spring response, as a result of designed magnetic force interactions. A discussion of fatigue performance is presented and it is suggested that whilst fabricating, the raster of the suspension element is printed perpendicular to the flexural direction and that the experienced stress is as low as possible during operation, to ensure longevity. A demonstrated power of ˜25 μW at 0.1 g is achieved and 2.9 mW is demonstrated at 1 g. The corresponding bandwidths reach up-to 4.5 Hz. The system’s corresponding power density of ˜0.48 mW cm-3 and normalised power integral density of 11.9 kg m-3 (at 1 g) are comparable to other in-plane systems found in the literature.
A dimensionless analysis of a 2DOF piezoelectric vibration energy harvester
NASA Astrophysics Data System (ADS)
Xiao, Han; Wang, Xu; John, Sabu
2015-06-01
In this study, a dimensionless analysis method is proposed to predict the output voltage and harvested power for a 2DOF vibration energy harvesting system. This method allows us to compare the harvesting power and efficiency of the 2DOF vibration energy harvesting system and to evaluate the harvesting system performance regardless the sizes or scales. The analysis method is a hybrid of time domain simulation and frequency response analysis approaches, which would be a useful tool for parametric study, design and optimisation of a 2DOF piezoelectric vibration energy harvester. In a case study, a quarter car suspension model with a piezoelectric material insert is chosen to be studied. The 2DOF vibration energy harvesting system could potentially be applied in a vehicle to convert waste or harmful ambient vibration energy into electrical energy for charging the battery. Especially for its application in a hybrid vehicle or an electrical vehicle, the 2DOF vibration energy harvesting system could improve charge mileage, comfort and reliability.
Relativistic rotation-vibrational energies for the Cs2 molecule
NASA Astrophysics Data System (ADS)
Jia, Chun-Sheng; Jia, Yue
2017-01-01
We present bound state solutions of the Dirac equation with the improved Rosen-Morse potential energy model. In the non-relativistic limit, the relativistic energy equation becomes the non-relativistic rotation-vibrational energy expression of the diatomic molecule. We find that the relativistic effect of the relative motion of the ions produces an obvious decrease in the vibrational energies for the 33Σg + state of the Cs2 molecule. It is observed that the behavior of the relativistic rotation-vibrational energies in larger rotational quantum numbers remains similar to that of the system with zero rotational quantum number.
Vibration Powered RF-Transponder for Sensing Low Frequency Motion Events
NASA Astrophysics Data System (ADS)
Gupta, S. K.; Pinrod, V.; Nadig, S.; Davaji, B.; Lal, A.
2016-11-01
Vibration energy harvesting offers a pathway to developing battery-less sensing solutions to be deployed in wireless sensor network nodes. The integration of the energy harvesters require regulation by power conditioning and control circuitry that consume some of the energy generated, reducing the effective energy available for node function. By designing a unique 3D-printed plastic structure for low frequency sensitivity and mechanical switching, and a lateral PZT bimorph for capturing energy from environmental vibrations, we report a zero-power consumption RF-transponder capable of detecting and reporting motion events without a battery. We have successfully picked up wireless transmissions on an external receiver placed ∼25cm away from the transponder, shaken at 0.75 g and 20 Hz. We have additionally demonstrated the ability to harvest energy from 5 Hz vibrations up to just under 150 Hz. When placed on an oil-based electric generator, which vibrates when operating, the RF-transponder has successfully picked up the differing harmonics to identify the mode of operation as the economy or regular power setting.
Vibrational Energy Transfer of Diatomic Gases in Hypersonic Expanding Flows.
NASA Astrophysics Data System (ADS)
Ruffin, Stephen Merrick
In high temperature flows related to vehicles at hypersonic speeds significant excitation of the vibrational energy modes of the gas can occur. Accurate predictions of the vibrational state of the gas and the rates of vibrational energy transfer are essential to achieve optimum engine performance, for design of heat shields, and for studies of ground based hypersonic test facilities. The Landau -Teller relaxation model is widely used because it has been shown to give accurate predictions in vibrationally heating flows such as behind forebody shocks. However, a number of experiments in nozzles have indicated that it fails to accurately predict the rate of energy transfer in expanding, or cooling, flow regions and fails to predict the distribution of energy in the vibrational quantum levels. The present study examines the range of applicability of the Landau -Teller model in expanding flows and develops techniques which provide accurate predictions in expanding flows. In the present study, detailed calculations of the vibrational relaxation process of N_2 and CO in cooling flows are conducted. A coupled set of vibrational transition rate equations and quasi one-dimensional fluid dynamic equations is solved. Rapid anharmonic Vibration-Translation transition rates and Vibration -Vibration exchange collisions are found to be responsible for vibrational relaxation acceleration in situations of high vibrational temperature and low translational temperature. The predictions of the detailed master equation solver are in excellent agreement with experimental results. The exact degree of acceleration is cataloged in this study for N_2 and is found to be a function of both the translational temperature (T) and the ratio of vibrational to translational temperatures (T_{vib}/T). Non-Boltzmann population distributions are observed for values of T _{vib}/T as low as 2.0. The local energy transfer rate is shown to be an order of magnitude or more faster than the Landau-Teller model
Electret transducer for vibration-based energy harvesting
Hillenbrand, J. Sessler, G. M.; Pondrom, P.
2015-05-04
Vibration-based electret energy harvesters with soft cellular spacer rings are presented. These harvesters are closely related to recently introduced electret accelerometers; however, their development targets are partially differing. Various harvesters with seismic masses from 8 to 23 g and surface potentials in the 500 V regime were built and characterized and powers of up to 8 μW at about 2 kHz and an acceleration of 1 g were measured. An analytical model is presented which, for instance, allows the calculation of the frequency response of the power output into a given load resistance. Finally, experimental and calculated results are compared.
Wideband, low-frequency springless vibration energy harvesters: part II
NASA Astrophysics Data System (ADS)
Bendame, Mohamed; Abdel-Rahman, Eihab; Soliman, Mostafa
2016-11-01
This paper concludes a two-part investigation of a novel architecture for vibration energy harvesting (VEH), the springless VEH. In this part, we study vertical springless electromagnetic VEHs where the direction of motion is aligned with the gravitational field. Experimental results show the existence of three topologies in the response of vertical springless VEHs; linear, single-impact, and double-impact. A model, encompassing all three topologies, was developed and validated by comparison to experimental results. We found that vertical springless VEHs demonstrate low frequency harvesting (<20 Hz), widebeand harvesting (bandwidths up to \\text{BW}=11.2 Hz), and an optimal output power of P = 7.52 mW at a base acceleration of 0.6 g. While horizontal springless VEHs typically offer more output power, the single-impact regime of the vertical springless VEHs offers the simultaneous advantages of wider harvesting bandwidths at lower operating frequencies.
Validation of a hybrid electromagnetic-piezoelectric vibration energy harvester
NASA Astrophysics Data System (ADS)
Edwards, Bryn; Hu, Patrick A.; Aw, Kean C.
2016-05-01
This paper presents a low frequency vibration energy harvester with contact based frequency up-conversion and hybrid electromagnetic-piezoelectric transduction. An electromagnetic generator is proposed as a power source for low power wearable electronic devices, while a second piezoelectric generator is investigated as a potential power source for a power conditioning circuit for the electromagnetic transducer output. Simulations and experiments are conducted in order to verify the behaviour of the device under harmonic as well as wide-band excitations across two key design parameters—the length of the piezoelectric beam and the excitation frequency. Experimental results demonstrated that the device achieved a power output between 25.5 and 34 μW at an root mean squared (rms) voltage level between 16 and 18.5 mV for the electromagnetic transducer in the excitation frequency range of 3-7 Hz, while the output power of the piezoelectric transducer ranged from 5 to 10.5 μW with a minimum peak-to-peak output voltage of 6 V. A multivariate model validation was performed between experimental and simulation results under wide-band excitation in terms of the rms voltage outputs of the electromagnetic and piezoelectric transducers, as well as the peak-to-peak voltage output of the piezoelectric transducer, and it is found that the experimental data fit the model predictions with a minimum probability of 63.4% across the parameter space.
Note: Vibration energy harvesting based on a round acoustic fence
NASA Astrophysics Data System (ADS)
Cui, Xiao-bin; Huang, Cheng-ping; Hu, Jun-hui
2015-07-01
An energy harvester based on a round acoustic fence (RAF) has been proposed and studied. The RAF is composed of cylindrical stubs stuck in a circular array on a thin metal plate, which can confine the acoustic energy efficiently. By removing one stub and thus opening a small gap in the RAF, acoustic leakage with larger intensity can be produced at the gap opening. With the vibration source surrounded by the RAF, the energy harvesting at the gap opening has a wide bandwidth and is insensitive to the position of the vibration source. The results may have potential applications in harvesting the energy of various vibration sources in solid structure.
Energy harvesting from vibration with cross-linked polypropylene piezoelectrets
Zhang, Xiaoqing; Wu, Liming; Sessler, Gerhard M.
2015-07-15
Piezoelectret films are prepared by modification of the microstructure of polypropylene foam sheets cross-linked by electronic irradiation (IXPP), followed by proper corona charging. Young’s modulus, relative permittivity, and electromechanical coupling coefficient of the fabricated films, determined by dielectric resonance spectra, are about 0.7 MPa, 1.6, and 0.08, respectively. Dynamic piezoelectric d{sub 33} coefficients up to 650 pC/N at 200 Hz are achieved. The figure of merit (FOM, d{sub 33} ⋅ g{sub 33}) for a more typical d{sub 33} value of 400 pC/N is about 11.2 GPa{sup −1}. Vibration-based energy harvesting with one-layer and two-layer stacks of these films is investigated at various frequencies and load resistances. At an optimum load resistance of 9 MΩ and a resonance frequency of 800 Hz, a maximum output power of 120 μW, referred to the acceleration g due to gravity, is obtained for an energy harvester consisting of a one-layer IXPP film with an area of 3.14 cm{sup 2} and a seismic mass of 33.7 g. The output power can be further improved by using two-layer stacks of IXPP films in electric series. IXPP energy harvesters could be used to energize low-power electronic devices, such as wireless sensors and LED lights.
NASA Astrophysics Data System (ADS)
Harne, Ryan L.
2012-04-01
Vibrational energy harvesting devices are oftentimes constructed in a manner identical to classical tuned-massdampers used in vibration control applications. However, many applications and models in past work assume that the harvesters will have negligible influence on the host structure (e.g. harvesters on a bridge). In contrast, this work adopts the perspective that the energy harvester is analogous to an electromechanical vibration absorber, attenuating the structural vibrations via a dominant mechanical influence while converting the absorbed energy into electric power. One embodiment of a device serving these two purposes-passive vibration attenuation and energy harvesting-is introduced. The device utilizes a distributed piezoelectric spring layer such that as the spring is strained between the top mass layer and the vibrating host structure the piezoelectric spring generates a voltage potential across its electrodes. Two experimental studies are detailed which investigate the capability for energy harvesting vibration absorbers to meet both goals. It is found that achievement of both objectives may require compromise but with proper device design still yields a viable electrical output.
The Role of Resonant Vibrations in Electronic Energy Transfer
Somsen, Oscar J. G.; Novoderezhkin, Vladimir I.; Mančal, Tomáš; van Grondelle, Rienk
2016-01-01
Abstract Nuclear vibrations play a prominent role in the spectroscopy and dynamics of electronic systems. As recent experimental and theoretical studies suggest, this may be even more so when vibrational frequencies are resonant with transitions between the electronic states. Herein, a vibronic multilevel Redfield model is reported for excitonically coupled electronic two‐level systems with a few explicitly included vibrational modes and interacting with a phonon bath. With numerical simulations the effects of the quantized vibrations on the dynamics of energy transfer and coherence in a model dimer are illustrated. The resonance between the vibrational frequency and energy gap between the sites leads to a large delocalization of vibronic states, which then results in faster energy transfer and longer‐lived mixed coherences. PMID:26910485
Enhanced vibration based energy harvesting using embedded acoustic black holes
NASA Astrophysics Data System (ADS)
Zhao, L.; Semperlotti, F.; Conlon, S. C.
2014-03-01
In this paper, we investigate the use of dynamic structural tailoring via the concept of an Acoustic Black Hole (ABH) to enhance the performance of piezoelectric based energy harvesting from operational mechanical vibrations. The ABH is a variable thickness structural feature that can be embedded in the host structure allowing a smooth reduction of the phase velocity while minimizing the amplitude of reflected waves. The ABH thickness variation is typically designed according to power-law profiles. As a propagating wave enters the ABH, it is progressively slowed down while its wavelength is compressed. This effect results in structural areas with high energy density that can be exploited effectively for energy harvesting. The potential of ABH for energy harvesting is shown via a numerical study based on fully coupled finite element electromechanical models of an ABH tapered plate with surface mounted piezo-transducers. The performances of the novel design are evaluated by direct comparison with a non-tapered structure in terms of energy ratios and attenuation indices. Results show that the tailored structural design allows a drastic increase in the harvested energy both for steady state and transient excitation. Performance dependencies of key design parameters are also investigated.
Vibration suppression of composite laminated plate with nonlinear energy sink
NASA Astrophysics Data System (ADS)
Zhang, Ye-Wei; Zhang, Hao; Hou, Shuai; Xu, Ke-Fan; Chen, Li-Qun
2016-06-01
The composite laminated plate is widely used in supersonic aircraft. So, there are many researches about the vibration suppression of composite laminated plate. In this paper, nonlinear energy sink (NES) as an effective method to suppress vibration is studied. The coupled partial differential governing equations of the composite laminated plate with the nonlinear energy sink (NES) are established by using the Hamilton principle. The fourth-order Galerkin discrete method is used to truncate the partial differential equations, which are solved by numerical integration method. Meanwhile study about the precise effectiveness of the nonlinear energy sink (NES) by discussing the different installation location of the nonlinear energy sink (NES) at the same speed. The results indicate that the nonlinear energy sink (NES) can significantly suppress the severe vibration of the composite laminated plate with speed wind loadings in to protect the composite laminated plate from excessive vibration.
Vibration behavior of fuel-element vibration suppressors for the advanced power reactor
NASA Technical Reports Server (NTRS)
Adams, D. W.; Fiero, I. B.
1973-01-01
Preliminary shock and vibration tests were performed on vibration suppressors for the advanced power reactor for space application. These suppressors position the fuel pellets in a pin type fuel element. The test determined the effect of varying axial clearance on the behavior of the suppressors when subjected to shock and vibratory loading. The full-size suppressor was tested in a mockup model of fuel and clad which required scaling of test conditions. The test data were correlated with theoretical predictions for suppressor failure. Good agreement was obtained. The maximum difference with damping neglected was about 30 percent. Neglecting damping would result in a conservative design.
NASA Astrophysics Data System (ADS)
Elfrink, R.; Renaud, M.; Kamel, T. M.; de Nooijer, C.; Jambunathan, M.; Goedbloed, M.; Hohlfeld, D.; Matova, S.; Pop, V.; Caballero, L.; van Schaijk, R.
2010-10-01
This paper describes the characterization of thin-film MEMS vibration energy harvesters based on aluminum nitride as piezoelectric material. A record output power of 85 µW is measured. The parasitic-damping and the energy-harvesting performances of unpackaged and packaged devices are investigated. Vacuum and atmospheric pressure levels are considered for the packaged devices. When dealing with packaged devices, it is found that vacuum packaging is essential for maximizing the output power. Therefore, a wafer-scale vacuum package process is developed. The energy harvesters are used to power a small prototype (1 cm3 volume) of a wireless autonomous sensor system. The average power consumption of the whole system is less than 10 µW, and it is continuously provided by the vibration energy harvester.
NASA Astrophysics Data System (ADS)
Rantz, Robert; Roundy, Shad
2016-04-01
A tremendous amount of research has been performed on the design and analysis of vibration energy harvester architectures with the goal of optimizing power output; most studies assume idealized input vibrations without paying much attention to whether such idealizations are broadly representative of real sources. These "idealized input signals" are typically derived from the expected nature of the vibrations produced from a given source. Little work has been done on corroborating these expectations by virtue of compiling a comprehensive list of vibration signals organized by detailed classifications. Vibration data representing 333 signals were collected from the NiPS Laboratory "Real Vibration" database, processed, and categorized according to the source of the signal (e.g. animal, machine, etc.), the number of dominant frequencies, the nature of the dominant frequencies (e.g. stationary, band-limited noise, etc.), and other metrics. By categorizing signals in this way, the set of idealized vibration inputs commonly assumed for harvester input can be corroborated and refined, and heretofore overlooked vibration input types have motivation for investigation. An initial qualitative analysis of vibration signals has been undertaken with the goal of determining how often a standard linear oscillator based harvester is likely the optimal architecture, and how often a nonlinear harvester with a cubic stiffness function might provide improvement. Although preliminary, the analysis indicates that in at least 23% of cases, a linear harvester is likely optimal and in no more than 53% of cases would a nonlinear cubic stiffness based harvester provide improvement.
Berschin, G; Sommer, H-M
2010-03-01
Muscle exercise using whole body vibration platforms is well known as an alternative physical exercise in therapy as well as in high performance sports. Various studies could show an effectiveness in particular to improve maximal strength and springiness. Using these platforms there is no consideration to posture although the damage potential of vibration stress i. e. on intervertebral discs is well-known. Therefore the effect of posture on the transmission and absorption of vibration loads in bipedal standing was examined in a study with 20 sport students. They were exposed to a whole body vibration load in bipedal standing at a vibration frequency of 25 Hz. The transmission of energy was measured at the head in different postural positions. An average transmission of 9 % was measured in spontaneous bipedal standing. It significantly decreased with gradual changes of posture. After 6 weeks posture conditioning exercise this effect was significantly improved. In conclusion different posture in bipedal standing implies not only different energy absorption but also different effects on muscle performance which can explain the partly inconsistent results after vibration exercise. In addition whole body vibration exercise in a prone or sitting position may increase the risk of overload and should be avoided because of reduced energy absorption capacity.
NASA Astrophysics Data System (ADS)
Zhao, S.; Erturk, A.
2013-01-01
We present electroelastic modeling, analytical and numerical solutions, and experimental validations of piezoelectric energy harvesting from broadband random vibrations. The modeling approach employed herein is based on a distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included, since broadband random vibrations, such as Gaussian white noise, might excite higher vibration modes. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given power spectral density (PSD) or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first of the two numerical solution methods employs the Fourier series representation of the base acceleration history in an ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H bimorph under different random excitation levels. The simulations exhibit very good agreement with the experimental measurements for a range of resistive electrical boundary conditions and input PSD levels. It is also shown that lightly damped higher vibration modes can alter the expected power curve under broadband random excitation. Therefore, the distributed-parameter modeling and solutions presented herein can be used as a more accurate alternative to the existing single-degree-of-freedom solutions for broadband random vibration energy harvesting.
Experimental study of a self-powered and sensing MR-damper-based vibration control system
NASA Astrophysics Data System (ADS)
Sapiński, Bogdan
2011-10-01
The paper deals with a semi-active vibration control system based on a magnetorheological (MR) damper. The study outlines the model and the structure of the system, and describes its experimental investigation. The conceptual design of this system involves harvesting energy from structural vibrations using an energy extractor based on an electromagnetic transduction mechanism (Faraday's law). The system consists of an electromagnetic induction device (EMI) prototype and an MR damper of RD-1005 series manufactured by Lord Corporation. The energy extracted is applied to control the damping characteristics of the MR damper. The model of the system was used to prove that the proposed vibration control system is feasible. The system was realized in the semi-active control strategy with energy recovery and examined through experiments in the cases where the control coil of the MR damper was voltage-supplied directly from the EMI or voltage-supplied via the rectifier, or supplied with a current control system with two feedback loops. The external loop used the sky-hook algorithm whilst the internal loop used the algorithm switching the photorelay, at the output from the rectifier. Experimental results of the proposed vibration control system were compared with those obtained for the passive system (MR damper is off-state) and for the system with an external power source (conventional system) when the control coil of the MR damper was supplied by a DC power supply and analogue voltage amplifier or a DC power supply and a photorelay. It was demonstrated that the system is able to power-supply the MR damper and can adjust itself to structural vibrations. It was also found that, since the signal of induced voltage from the EMI agrees well with that of the relative velocity signal across the damper, the device can act as a 'velocity-sign' sensor.
Two methods for damping torsional vibrations in DFIG-based wind generators using power converters
NASA Astrophysics Data System (ADS)
Zhao, Zuyi; Lu, Yupu; Xie, Da; Yu, Songtao; Wu, Wangping
2017-01-01
This paper proposes novel damping control algorithms by using static synchronous compensator (STATCOM) and energy storage system (ESS) to damp torsional vibrations in doubly fed induction generator (DFIG) based wind turbine systems. It first analyses the operating characteristics of STATCOM and ESS for regulating power variations to increase grid voltage stability. Then, new control strategies for STATCOM and ESS are introduced to damp the vibrations. It is followed by illustration of their effectiveness to damp the drive train torsional vibrations of wind turbines, which can be caused by grid disturbances, such as voltage sags and frequency fluctuations. Results suggest that STATCOM is a promising technology to mitigate the torsional vibrations caused by grid voltage sags. By contrast, the ESS connected to the point of common coupling (PCC) of wind turbine systems shows even obvious advantages because of its capability of absorbing/releasing both active and reactive power. It can thus be concluded that STATCOM is useful for stabilizing power system voltage fluctuations, and ESS is more effective both in regulating PCC voltage fluctuations and damping torsional vibrations caused by grid voltage frequency fluctuations.
NASA Astrophysics Data System (ADS)
Harne, Ryan L.
2012-03-01
Fundamental studies in vibrational energy harvesting consider the electromechanically coupled devices to be excited by uniform base vibration. Since many harvester devices are mass-spring systems, there is a clear opportunity to exploit the mechanical resonance in a fashion identical to tuned mass dampers to simultaneously suppress the vibration of the host structure via reactive forces while converting the ‘absorbed’ vibration into electrical power. This paper presents a general analytical model for the coupled electro-elastic dynamics of a vibrating panel to which distributed energy harvesting devices are attached. One such device is described which employs a corrugated piezoelectric spring layer. The model is validated by comparison to measured elastic and electric frequency response functions. Tests on an excited panel show that the device, contributing 1% additional mass to the structure, concurrently attenuates the lowest panel mode accelerance by >20 dB while generating 0.441 µW for a panel drive acceleration of 3.29 m s-2. Adjustment of the load resistance connected to the piezoelectric spring layer verifies the analogy between the present harvester device and an electromechanically stiffened and damped vibration absorber. The results show that maximum vibration suppression and energy harvesting objectives occur for nearly the same load resistance in the harvester circuit.
Rotary bistable and Parametrically Excited Vibration Energy Harvesting
NASA Astrophysics Data System (ADS)
Kurmann, L.; Jia, Y.; Hoffmann, D.; Manoli, Y.; Woias, P.
2016-11-01
Parametric resonance is a type of nonlinear vibration phenomenon [1], [2] induced from the periodic modulation of at least one of the system parameters and has the potential to exhibit interesting higher order nonlinear behaviour [3]. Parametrically excited vibration energy harvesters have been previously shown to enhance both the power amplitude [4] and the frequency bandwidth [5] when compared to the conventional direct resonant approach. However, to practically activate the more profitable regions of parametric resonance, additional design mechanisms [6], [7] are required to overcome a critical initiation threshold amplitude. One route is to establish an autoparametric system where external direct excitation is internally coupled to parametric excitation [8]. For a coupled two degrees of freedom (DoF) oscillatory system, principal autoparametric resonance can be achieved when the natural frequency of the first DoF f1 is twice that of the second DoF f2 and the external excitation is in the vicinity of f1. This paper looks at combining rotary and translatory motion and use autoparametric resonance phenomena.
A diamagnetically stabilized horizontally levitated electromagnetic vibration energy harvester
NASA Astrophysics Data System (ADS)
Palagummi, S.; Zou, J.; Yuan, F. G.
2015-04-01
This article investigates a horizontal diamagnetic levitation (HDL) system for vibration energy harvesting. In this configuration, two large magnets, alias lifting magnets, are arranged co-axially at a distance such that in between them a magnet, alias floating magnet, is passively levitated at a laterally offset equilibrium position. The levitation is stabilized in the horizontal direction by two diamagnetic plates made of pyrolytic graphite placed on each side of the floating magnet. This HDL configuration permits large amplitude vibration of the floating magnet and exploits the ability to tailor the geometry to meet specific applications due to its frequency tuning capability. Theoretical modeling techniques are discussed followed by an experimental setup to validate it. At an input root mean square (RMS) acceleration of 0.0434 m/s2 (0.0044 grms) and at a resonant frequency of 1.2 Hz, the prototype generated a RMS power of 3.6 μW with an average system efficiency of 1.93%. Followed by the validation, parametric studies on the geometry of the components are undertaken to show that with the optimized parameters the efficiency can be further enhanced.
Zhang, Yulong; Wang, Tianyang; Zhang, Ai; Peng, Zhuoteng; Luo, Dan; Chen, Rui; Wang, Fei
2016-12-01
In this paper, we present design and test of a broadband electrostatic energy harvester with a dual resonant structure, which consists of two cantilever-mass subsystems each with a mass attached at the free edge of a cantilever. Comparing to traditional devices with single resonant frequency, the proposed device with dual resonant structure can resonate at two frequencies. Furthermore, when one of the cantilever-masses is oscillating at resonance, the vibration amplitude is large enough to make it collide with the other mass, which provides strong mechanical coupling between the two subsystems. Therefore, this device can harvest a decent power output from vibration sources at a broad frequency range. During the measurement, continuous power output up to 6.2-9.8 μW can be achieved under external vibration amplitude of 9.3 m/s(2) at a frequency range from 36.3 Hz to 48.3 Hz, which means the bandwidth of the device is about 30% of the central frequency. The broad bandwidth of the device provides a promising application for energy harvesting from the scenarios with random vibration sources. The experimental results indicate that with the dual resonant structure, the vibration-to-electricity energy conversion efficiency can be improved by 97% when an external random vibration with a low frequency filter is applied.
Density-noise power fluctuations in vibrated granular media
NASA Astrophysics Data System (ADS)
Nowak, E. R.; Grushin, A.; Barnum, A. C.; Weissman, M. B.
2001-02-01
The noise power spectra of the fluctuations in density of a vibrated column of granular material are found to be time dependent. Spectral analysis of these noise power fluctuations shows nontrivial frequency dependences. The noise powers at different frequencies are also found to fluctuate in a partially correlated way. In most instances, the slow variations of the noise are strongly correlated over a broad range of frequencies. These results indicate that highly cooperative interactions exist between fluctuators. In contrast, effects of such strongly coupled fluctuators are absent in the one-dimensional parking-lot-model, one of the simplest systems used to provide a model for recent granular compaction experiments.
Vibrational energy transfer dynamics in ruthenium polypyridine transition metal complexes.
Fedoseeva, Marina; Delor, Milan; Parker, Simon C; Sazanovich, Igor V; Towrie, Michael; Parker, Anthony W; Weinstein, Julia A
2015-01-21
Understanding the dynamics of the initial stages of vibrational energy transfer in transition metal complexes is a challenging fundamental question which is also of crucial importance for many applications, such as improving the performance of solar devices or photocatalysis. The present study investigates vibrational energy transport in the ground and the electronic excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2, a close relative of the efficient "N3" dye used in dye-sensitized solar cells. Using the emerging technique of ultrafast two-dimensional infrared spectroscopy, we show that, similarly to other transition-metal complexes, the central Ru heavy atom acts as a "bottleneck" making the energy transfer from small ligands with high energy vibrational stretching frequencies less favorable and thereby affecting the efficiency of vibrational energy flow in the complex. Comparison of the vibrational relaxation times in the electronic ground and excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2 shows that it is dramatically faster in the latter. We propose to explain this observation by the intramolecular electrostatic interactions between the thiocyanate group and partially oxidised Ru metal center, which increase the degree of vibrational coupling between CN and Ru-N modes in the excited state thus reducing structural and thermodynamic barriers that slow down vibrational relaxation and energy transport in the electronic ground state. As a very similar behavior was earlier observed in another transition-metal complex, Re(4,4'-(COOEt)2-2,2'-bpy)(CO)3Cl, we suggest that this effect in vibrational energy dynamics might be common for transition-metal complexes with heavy central atoms.
Improvement of force factor of magnetostrictive vibration power generator for high efficiency
NASA Astrophysics Data System (ADS)
Kita, Shota; Ueno, Toshiyuki; Yamada, Sotoshi
2015-05-01
We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 × 1.5 × 50 mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73 W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration.
Improvement of force factor of magnetostrictive vibration power generator for high efficiency
Kita, Shota Ueno, Toshiyuki; Yamada, Sotoshi
2015-05-07
We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 × 1.5 × 50 mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73 W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration.
Heavy atom vibrational modes and low-energy vibrational autodetachment in nitromethane anions.
Thompson, Michael C; Baraban, Joshua H; Matthews, Devin A; Stanton, John F; Weber, J Mathias
2015-06-21
We report infrared spectra of nitromethane anion, CH3NO2 (-), in the region 700-2150 cm(-1), obtained by Ar predissociation spectroscopy and electron detachment spectroscopy. The data are interpreted in the framework of second-order vibrational perturbation theory based on coupled-cluster electronic structure calculations. The modes in the spectroscopic region studied here are mainly based on vibrations involving the heavier atoms; this work complements earlier studies on nitromethane anion that focused on the CH stretching region of the spectrum. Electron detachment begins at photon energies far below the adiabatic electron affinity due to thermal population of excited vibrational states.
A Detailed Level Kinetics Model of NO Vibrational Energy Distributions
NASA Technical Reports Server (NTRS)
Sharma, Surendra P.; Gilmore, John; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Several contemporary problems have pointed to the desirability of a detailed level kinetics approach to modeling the distribution of vibrational energy in NO. Such a model is necessary when vibrational redistribution reactions are insufficient to maintain a Boltzmann distribution over the vibrational energy states. Recent calculations of the rate constant for the first reaction of the Zeldovich mechanism (N2 + O (goes to) NO + N) have suggested that the product NO is formed in high vibrational states. In shock layer flowfields, the product NO molecules may experience an insufficient number of collisions to establish a Boltzmann distribution over vibrational states, thus necessitating a level kinetics model. In other flows, such as expansions of high temperature air, fast, near-resonance vibrational energy exchanges with N2 and O2 may also require a level specific model for NO because of the relative rates of vibrational exchange and redistribution. The proposed report will integrate computational and experimental components to construct such a model for the NO molecule.
NASA Astrophysics Data System (ADS)
Kajihara, Tadao; Ueno, Yoshikazu; Tsujiura, Yuichi; Koshiba, Yasuko; Morimoto, Masahiro; Kanno, Isaku; Ishida, Kenji
2017-04-01
We investigated piezoelectric vibration energy harvesters with poly(vinylidene fluoride/trifluoroethylene) films and the improved power generation from using multistacked and stretched ferroelectric films on the cantilevers. The energy harvesters generated electric power with a resonant frequency of approximately 25 Hz, which corresponded to the ambient vibration. The power density of four-layered harvesters was estimated to be 2.5 µW/m3, which was larger than the power density of previous harvesters. The output power of stretched-film harvesters was 3.6 times the output obtained from unstretched films. In addition, because organic ferroelectric films are flexible, the resonant frequency of each harvester was practically constant even when using the techniques of multistacking and stretching.
Spectroscopic probes of vibrationally excited molecules at chemically significant energies
Rizzo, T.R.
1993-12-01
This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.
A magnetic-spring-based, low-frequency-vibration energy harvester comprising a dual Halbach array
NASA Astrophysics Data System (ADS)
Salauddin, M.; Halim, M. A.; Park, J. Y.
2016-09-01
Energy harvesting that uses low-frequency vibrations is attractive due to the availability of such vibrations throughout the ambient environment. Significant power generation at low-frequency vibrations, however, is challenging because the power flow decreases as the frequency decreases; moreover, designing a spring-mass system that is suitable for low-frequency-vibration energy harvesting is difficult. In this work, our proposed device overcomes both of these challenges by using a dual Halbach array and magnetic springs. Each Halbach array concentrates the magnetic-flux lines on one side of the array while suppressing the flux lines on the other side; therefore, a dual Halbach array allows for an interaction between the concentrated magnetic-flux lines and the same coil so that the maximum flux linkage occurs. During the experiment, vibration was applied in a horizontal direction to reduce the gravity effect on the Halbach-array structure. To achieve an increased power generation at low-amplitude and low-frequency vibrations, the magnetic structure of the dual Halbach array and the magnetic springs were optimized in terms of the operating frequency and the power density; subsequently, a prototype was fabricated and tested. The prototype device offers a normalized power density of 133.45 μW cm-3 g-2 that is much higher than those of recently reported electromagnetic energy harvesters; furthermore, it is capable of delivering a maximum average power of 1093 μW to a 44 Ω optimum load, at an 11 Hz resonant frequency and under a 0.5 g acceleration.
Sound power and vibration levels for two different piano soundboards
NASA Astrophysics Data System (ADS)
Squicciarini, Giacomo; Valiente, Pablo Miranda; Thompson, David J.
2016-09-01
This paper compares the sound power and vibration levels for two different soundboards for upright pianos. One of them is made of laminated spruce and the other of solid spruce (tone-wood). These differ also in the number of ribs and manufacturing procedure. The methodology used is defined in two major steps: (i) acoustic power due to a unit force is obtained reciprocally by measuring the acceleration response of the piano soundboards when excited by acoustic waves in reverberant field; (ii) impact tests are adopted to measure driving point and spatially-averaged mean-square transfer mobility. The results show that, in the midhigh frequency range, the soundboard made of solid spruce has a greater vibrational and acoustic response than the laminated soundboard. The effect of string tension is also addressed, showing that is only relevant at low frequencies.
A resonant electromagnetic vibration energy harvester for intelligent wireless sensor systems
Qiu, Jing Wen, Yumei; Li, Ping; Liu, Xin; Chen, Hengjia; Yang, Jin
2015-05-07
Vibration energy harvesting is now receiving more interest as a means for powering intelligent wireless sensor systems. In this paper, a resonant electromagnetic vibration energy harvester (VEH) employing double cantilever to convert low-frequency vibration energy into electrical energy is presented. The VEH is made up of two cantilever beams, a coil, and magnetic circuits. The electric output performances of the proposed electromagnetic VEH have been investigated. With the enhancement of turns number N, the optimum peak power of electromagnetic VEH increases sharply and the resonance frequency deceases gradually. When the vibration acceleration is 0.5 g, we obtain the optimum output voltage and power of 9.04 V and 50.8 mW at frequency of 14.9 Hz, respectively. In a word, the prototype device was successfully developed and the experimental results exhibit a great enhancement in the output power and bandwidth compared with other traditional electromagnetic VEHs. Remarkably, the proposed resonant electromagnetic VEH have great potential for applying in intelligent wireless sensor systems.
Chaos in vibrating systems with a limited power-supply.
Krasnopolskaya, Tatyana S.; Shvets, Alexander Yu.
1993-07-01
New models and properties of forced oscillations of the various physical systems (pendulum and piezoceramic transducer) due to the interaction with the excitation device of limited power-supply are investigated in details. Using an analysis of the largest Lyapunov exponent for a complicated system-vibrating subsystem and exciter-the regions for three steady state regimes are determined, namely: stationary, periodic and chaotic.
Power conditioning for low-voltage piezoelectric stack energy harvesters
NASA Astrophysics Data System (ADS)
Skow, E.; Leadenham, S.; Cunefare, K. A.; Erturk, A.
2016-04-01
Low-power vibration and acoustic energy harvesting scenarios typically require a storage component to be charged to enable wireless sensor networks, which necessitates power conditioning of the AC output. Piezoelectric beam-type bending mode energy harvesters or other devices that operate using a piezoelectric element at resonance produce high voltage levels, for which AC-DC converters and step-down DC-DC converters have been previously investigated. However, for piezoelectric stack energy harvesters operating off-resonance and producing low voltage outputs, a step-up circuit is required for power conditioning, such as seen in electromagnetic vibration energy scavengers, RF communications, and MEMS harvesters. This paper theoretically and experimentally investigates power conditioning of a low-voltage piezoelectric stack energy harvester.
Design improvements for an electret-based MEMS vibrational electrostatic energy harvester
NASA Astrophysics Data System (ADS)
Altena, G.; Renaud, M.; Elfrink, R.; Goedbloed, M. H.; de Nooijer, C.; van Schaijk, R.
2013-12-01
This paper presents several improvements to the design of an electret-based MEMS vibrational electrostatic energy harvester that have led to a two orders of magnitude increase in power compared to a previously presented device. The device in this paper has a footprint of approximately 1 cm2 and generated 175 μW. The following two improvements to the design are discussed: the electrical connection principle of the harvester and the electrode geometrical configuration. The measured performance of the device is compared with simulations. When exited by sinusoidal vibration, a device employing the two design improvements but with a higher resonance frequency and higher electret potential generated 495 μW AC power, which is the highest reported value for electret-based MEMS vibrational electrostatic energy harvesters with a similar footprint. This makes this device a promising candidate for the targeted application of wireless tire pressure monitoring systems (TPMS).
Energy 101: Concentrating Solar Power
None
2016-07-12
From towers to dishes to linear mirrors to troughs, concentrating solar power (CSP) technologies reflect and collect solar heat to generate electricity. A single CSP plant can generate enough power for about 90,000 homes. This video explains what CSP is, how it works, and how systems like parabolic troughs produce renewable power. For more information on the Office of Energy Efficiency and Renewable Energy's CSP research, see the Solar Energy Technology Program's Concentrating Solar Power Web page at http://www1.eere.energy.gov/solar/csp_program.html.
Energy transfer in mesoscopic vibrational systems enabled by eigenfrequency fluctuations
NASA Astrophysics Data System (ADS)
Atalaya, Juan
Energy transfer between low-frequency vibrational modes can be achieved by means of nonlinear coupling if their eigenfrequencies fulfill certain nonlinear resonance conditions. Because of the discreteness of the vibrational spectrum at low frequencies, such conditions may be difficult to satisfy for most low-frequency modes in typical mesoscopic vibrational systems. Fluctuations of the vibrational eigenfrequencies can also be relatively strong in such systems. We show that energy transfer between modes can occur in the absence of nonlinear resonance if frequency fluctuations are allowed. The case of three modes with cubic nonlinear coupling and no damping is particularly interesting. It is found that the system has a non-thermal equilibrium state which depends only on the initial conditions. The rate at which the system approaches to such state is determined by the parameters such as the noise strength and correlation time, the nonlinearity strength and the detuning from exact nonlinear resonance. We also discuss the case of many weakly coupled modes. Our results shed light on the problem of energy relaxation of low-frequency vibrational modes into the continuum of high-frequency vibrational modes. The results have been obtained with Mark Dykman. Alternative email: jatalaya2012@gmail.com.
Designing and Testing Energy Harvesters Suitable for Renewable Power Sources
NASA Astrophysics Data System (ADS)
Synkiewicz, B.; Guzdek, P.; Piekarski, J.; Zaraska, K.
2016-01-01
Energy harvesters convert waste power (heat, light and vibration) directly to electric power . Fast progress in their technology, design and areas of application (e.g. “Internet of Things”) has been observed recently. Their effectiveness is steadily growing which makes their application to powering sensor networks with wireless data transfer reasonable. The main advantage is the independence from wired power sources, which is especially important for monitoring state of environmental parameters. In this paper we describe the design and realization of a gas sensor monitoring CO level (powered by TEG) and two, designed an constructed in ITE, autonomous power supply modules powered by modern photovoltaic cells.
Vibrational energy transport in molecules and the statistical properties of vibrational modes
NASA Astrophysics Data System (ADS)
Pandey, Hari Datt; Leitner, David M.
2017-01-01
Statistical properties of the eigenmodes computed for two molecules, dodecane and perfluorododecane, are examined and compared with predictions of random matrix theory. The eigenmode statistics of the heat carrying modes of perfluorododecane correspond to Porter-Thomas statistics, whereas those for dodecane do not. Vibrational energy transport in the two molecules is also computed and found to be diffusive in perfluorododecane but not in dodecane, consistent with recent experiments. The correspondence between eigenmode statistics and vibrational energy transport dynamics in molecules as well as thermalization in molecules are discussed.
2011-11-01
2011 GreenGov Symposium Oct. 31 ‐ Nov. 2, 2011 Washington Hilton Washington, DC Clean Energy – Session 5 Increasing the DoD Renewable Energy...Rev. 8-98) Prescribed by ANSI Std Z39-18 Clean Energy – Session 5 Increasing the DoD Renewable Energy Portfolio November 1, 2011 Army Energy in... Clean Energy – Session 5 Increasing the DoD Renewable Energy Portfolio November 1, 2011 3 Army Energy Consumption, 2010 Facilities Vehicles
Killoran, N.; Huelga, S. F.; Plenio, M. B.
2015-10-21
Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system’s power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle’s relevance in parameter regimes connected to natural light-harvesting structures.
Killoran, N; Huelga, S F; Plenio, M B
2015-10-21
Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's relevance in parameter regimes connected to natural light-harvesting structures.
NASA Astrophysics Data System (ADS)
Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei
2014-04-01
Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.
Investigation of an energy harvesting MR damper in a vibration control system
NASA Astrophysics Data System (ADS)
Sapiński, Bogdan; Rosół, Maciej; Węgrzynowski, Marcin
2016-12-01
In this paper the authors investigate the performance of an energy harvesting MR damper (EH-MRD) employed in a semi-active vibration control system (SVCS) and used in a single DOF mechanical structure configuration. Main components of the newly proposed SCVS include the MR damper and an electromagnetic vibration energy harvester based on the Faraday’s law (EVEH) that converts vibration energy into electrical energy and delivers electrical power supplying the MR damper. The main objective of the study is to indicate that the SVCS, controlled by the specially designed embedded system, is feasible and presents good performance at the present stage of the research. The work describes investigation the unique features of the EH-MRD, i.e. its self-powering and self-sensing capabilities. Two cases were considered and the testing was done accordingly. In the case 1, only the self-powered capability was investigated. It was found out that harvested energy is sufficient to power the EH-MRD damper and to adjust it to structural vibration. The results confirmed the adequacy of the SVCS and demonstrated a significant reduction of the resonance peak. In the case 2, both the self-powering and self-sensing capabilities were investigated. Due to the self-sensing capability, the SCVS does not require any sensor. It appeared that thus harvested energy is sufficient to power the EH-MRD and enables self-sensing action since the signal of voltage induced by EVEH agrees with the relative velocity signal across the device. Similar to case 1, the resonance peak is significantly reduced.
Energy harvesting by means of flow-induced vibrations on aerospace vehicles
NASA Astrophysics Data System (ADS)
Li, Daochun; Wu, Yining; Da Ronch, Andrea; Xiang, Jinwu
2016-10-01
This paper reviews the design, implementation, and demonstration of energy harvesting devices that exploit flow-induced vibrations as the main source of energy. Starting with a presentation of various concepts of energy harvesters that are designed to benefit from a general class of flow-induced vibrations, specific attention is then given at those technologies that may offer, today or in the near future, a potential benefit to extend the operational capabilities and to monitor critical parameters of unmanned aerial vehicles. Various phenomena characterized by flow-induced vibrations are discussed, including limit cycle oscillations of plates and wing sections, vortex-induced and galloping oscillations of bluff bodies, vortex-induced vibrations of downstream structures, and atmospheric turbulence and gusts. It was found that linear or linearized modeling approaches are commonly employed to support the design phase of energy harvesters. As a result, highly nonlinear and coupled phenomena that characterize flow-induced vibrations are neglected in the design process. The Authors encourage a shift in the current design paradigm: considering coupled nonlinear phenomena, and adequate modeling tools to support their analysis, from a design limitation to a design opportunity. Special emphasis is placed on identifying designs and implementations applicable to aircraft configurations. Application fields of flow-induced vibrations-based energy harvesters are discussed including power supply for wireless sensor networks and simultaneous energy harvest and control. A large body of work on energy harvesters is included in this review journal. Whereas most of the references claim direct applications to unmanned aerial vehicles, it is apparent that, in most of the cases presented, the working principles and characteristics of the energy harvesters are incompatible with any aerospace applications. Finally, the challenges that hold back the integration of energy harvesting
Low Head, Vortex Induced Vibrations River Energy Converter
Bernitsas, Michael B.; Dritz, Tad
2006-06-30
Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.
Ionization energy and active cation vibrations of trans-2-fluorostyrene
NASA Astrophysics Data System (ADS)
Wu, Pei Ying; Tzeng, Sheng Yuan; Hsu, Ya Chu; Tzeng, Wen Bih
2017-02-01
We applied the two-color resonant two-photon mass-analyzed threshold ionization (MATI) technique to record the cation spectra of trans-2-fluorostyrene by ionizing via six intermediate vibronic levels. The adiabatic ionization energy was determined to be 69 304 ± 5 cm-1. The distinct MATI bands at 67, 124, 242, 355, 737, 806, 833, and 993 cm-1 were assigned to the active cation vibrations related to out-of-plane substituent-sensitive bending vibrations and in-plane ring deformation and bending motions. Many combination vibrations were also observed. Our experimental results suggest that the molecular geometry and vibrational coordinates of the trans-2-fluorostyrene cation in the D0 state resemble those of the neutral species in the S1 state.
Accurate Measurement of Velocity and Acceleration of Seismic Vibrations near Nuclear Power Plants
NASA Astrophysics Data System (ADS)
Arif, Syed Javed; Imdadullah; Asghar, Mohammad Syed Jamil
In spite of all prerequisite geological study based precautions, the sites of nuclear power plants are also susceptible to seismic vibrations and their consequent effects. The effect of the ongoing nuclear tragedy in Japan caused by an earthquake and its consequent tsunami on March 11, 2011 is currently beyond contemplations. It has led to a rethinking on nuclear power stations by various governments around the world. Therefore, the prediction of location and time of large earthquakes has regained a great importance. The earth crust is made up of several wide, thin and rigid plates like blocks which are in constant motion with respect to each other. A series of vibrations on the earth surface are produced by the generation of elastic seismic waves due to sudden rupture within the plates during the release of accumulated strain energy. The range of frequency of seismic vibrations is from 0 to 10 Hz. However, there appears a large variation in magnitude, velocity and acceleration of these vibrations. The response of existing or conventional methods of measurement of seismic vibrations is very slow, which is of the order of tens of seconds. A systematic and high resolution measurement of velocity and acceleration of these vibrations are useful to interpret the pattern of waves and their anomalies more accurately, which are useful for the prediction of an earthquake. In the proposed work, a fast rotating magnetic field (RMF) is used to measure the velocity and acceleration of seismic vibrations in the millisecond range. The broad spectrum of pulses within one second range, measured by proposed method, gives all possible values of instantaneous velocity and instantaneous acceleration of the seismic vibrations. The spectrum of pulses in millisecond range becomes available which is useful to measure the pattern of fore shocks to predict the time and location of large earthquakes more accurately. Moreover, instead of average, the peak values of these quantities are helpful
Zhao, Nian; Yang, Jin Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping
2016-01-15
This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.
Power management for energy harvesting wireless sensors
NASA Astrophysics Data System (ADS)
Arms, S. W.; Townsend, C. P.; Churchill, D. L.; Galbreath, J. H.; Mundell, S. W.
2005-05-01
The objective of this work was to demonstrate smart wireless sensing nodes capable of operation at extremely low power levels. These systems were designed to be compatible with energy harvesting systems using piezoelectric materials and/or solar cells. The wireless sensing nodes included a microprocessor, on-board memory, sensing means (1000 ohm foil strain gauge), sensor signal conditioning, 2.4 GHz IEEE 802.15.4 radio transceiver, and rechargeable battery. Extremely low power consumption sleep currents combined with periodic, timed wake-up was used to minimize the average power consumption. Furthermore, we deployed pulsed sensor excitation and microprocessor power control of the signal conditioning elements to minimize the sensors" average contribution to power draw. By sleeping in between samples, we were able to demonstrate extremely low average power consumption. At 10 Hz, current consumption was 300 microamps at 3 VDC (900 microwatts); at 5 Hz: 400 microwatts, at 1 Hz: 90 microwatts. When the RF stage was not used, but data were logged to memory, consumption was further reduced. Piezoelectric strain energy harvesting systems delivered ~2000 microwatts under low level vibration conditions. Output power levels were also measured from two miniature solar cells; which provided a wide range of output power (~100 to 1400 microwatts), depending on the light type & distance from the source. In summary, system power consumption may be reduced by: 1) removing the load from the energy harvesting & storage elements while charging, 2) by using sleep modes in between samples, 3) pulsing excitation to the sensing and signal conditioning elements in between samples, and 4) by recording and/or averaging, rather than frequently transmitting, sensor data.
Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; ...
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this report, we present a theoretical formalism to demonstrate themore » slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. In conclusion, we also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions« less
Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R.
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.
Dong, Hui; Lewis, Nicholas H C; Oliver, Thomas A A; Fleming, Graham R
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.
Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R.
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this report, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. In conclusion, we also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions
NASA Astrophysics Data System (ADS)
Harne, R. L.
2013-04-01
Vibrational energy harvesting devices are often designed in a manner analogous to classical dynamic vibration absorbers (DVAs). An electromechanical mass-spring system is devised so as to resonate at the frequency most dominant in the environmental vibration spectrum; the consequent device oscillation is converted to a electrical signal which is harnessed for immediate usage or as a charging mechanism for a battery. The DVA is likewise designed but with the intention of inducing substantial inertial influence upon a host structure for vibration control purposes, either to globally dampen the vibration of the main body or, in an undamped configuration to "absorb" the primary system vibration at a single frequency. This paper describes the development of an electromechanical mass-spring-damper which seeks to serve both goals of passive vibration control and energy harvesting. The device utilizes a piezoelectric film spring and a distributed mass layer so as to be suitable for the attenuation of surface vibrations and to convert a portion of the absorbed energy into electric power. The development and design of the device are presented and the results of realistic tests are provided to show both the potentials and the challenges encountered when attempting to superpose the goals of vibration control and energy harvesting.
Calculating vibrational spectra using modified Shepard interpolated potential energy surfaces.
Evenhuis, Christian R; Manthe, Uwe
2008-07-14
A potential energy interpolation approach based on modified Shepard interpolation and specifically designed for calculation of vibrational states is presented. The importance of the choice of coordinates for the rate of convergence is demonstrated. Studying the vibrational states of the water molecule as a test case, a coordinate system comprised of inverse bond distances and trigonometric functions of the bond angle is found to be particularly efficient. Different sampling schemes used to locate the reference points in the modified Shepard interpolation are investigated. A final scheme is recommended, which allows the construction of potential energy surfaces to sub-wave-number accuracy.
Vibrational energy relaxation in liquid oxygen
NASA Astrophysics Data System (ADS)
Everitt, K. F.; Egorov, S. A.; Skinner, J. L.
1998-09-01
We consider theoretically the relaxation from the first excited vibrational state to the ground state of oxygen molecules in neat liquid oxygen. The relaxation rate constant is related in the usual way to the Fourier transform of a certain quantum mechanical force-force time-correlation function. A result from Egelstaff allows one instead to relate the rate constant (approximately) to the Fourier transform of a classical force-force time-correlation function. This Fourier transform is then evaluated approximately by calculating three equilibrium averages from a classical molecular dynamics simulation. Our results for the relaxation times (at two different temperatures) are within a factor of 5 of the experimental relaxation times, which are in the ms range.
Delayed-feedback vibration absorbers to enhance energy harvesting
NASA Astrophysics Data System (ADS)
Kammer, Ayhan S.; Olgac, Nejat
2016-02-01
Recovering energy from ambient vibrations has recently been a popular research topic. This article is conceived as a concept study that explores new directions to enhance the performance of such energy harvesting devices from base excitation. The main idea revolves around the introduction of delayed feedback sensitization (or tuning) of an active vibration absorber setup. To clarify the concept, the Delayed Resonator theory is reviewed and its suitability for energy harvesting purposes is studied. It is recognized that an actively tuned and purely resonant absorber is infeasible for such applications. The focus is then shifted to alternative tuning schemes that deviate from resonance conditions. Also called Delayed Feedback Vibration Absorbers, these devices may indeed provide significant enhancements in energy harvesting capacity. Analytical developments are presented to study energy generation and consumption characteristics. Effects of excitation frequency and absorber damping are investigated. The influences of time-delayed feedback on the stability and the transient performance of the system are also treated. The analysis starts from a stand-alone absorber, emulating seismic mass type harvesters. The work is then extended to vibration control applications, where an absorber/harvester is coupled with a primary structure. The results are demonstrated with numerical simulations on a case study.
A nanogenerator as a self-powered sensor for measuring the vibration spectrum of a drum membrane.
Yu, Aifang; Zhao, Yong; Jiang, Peng; Wang, Zhong Lin
2013-02-08
A nanogenerator (NG) is a device that converts vibration energy into electricity. Here, a flexible, small size and lightweight NG is successfully demonstrated as an active sensor for detecting the vibration spectrum of a drum membrane without the use of an external power source. The output current/voltage signal of the NG is a direct measure of the strain of the local vibrating drum membrane that contains rich informational content, such as, notably, the vibration frequency, vibration speed and vibration amplitude. In comparison to the laser vibrometer, which is excessively complex and expensive, this kind of small and low cost sensor based on an NG is also capable of detecting the local vibration frequency of a drum membrane accurately. A spatial arrangement of the NGs on the membrane can provide position-dependent vibration information on the surface. The measured frequency spectrum can be understood on the basis of the theoretically calculated vibration modes. This work expands the application of NGs and reveals the potential for developing sound wave detection, environmental/infrastructure monitoring and many more applications.
Influence of Packing on Low Energy Vibrations of Densified Glasses
NASA Astrophysics Data System (ADS)
Carini, Giovanni, Jr.; Carini, Giuseppe; D'Angelo, Giovanna; Tripodo, Gaspare; Di Marco, Gaetano; Vasi, Cirino; Gilioli, Edmondo
2013-12-01
A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples of B2O3, which have been high-pressure quenched to go through different glassy phases having growing density to the crystalline state. It has revealed that the excess volume characterizing the glassy networks favors the formation of specific glassy structural units, the boroxol rings, which produce the boson peak, a broad band of low energy vibrational states. The decrease of boroxol rings with increasing pressure of synthesis is associated with the progressive depression of the excess low energy vibrations until their full disappearance in the crystalline phase, where the rings are missing. These observations prove that the additional soft vibrations in glasses arise from specific units whose formation is made possible by the poor atomic packing of the network.
A novel vibrational energy harvester with electric double layer electrets
NASA Astrophysics Data System (ADS)
Ono, S.; Miwa, K.; Iori, J.; Mitsuya, H.; Ishibashi, K.; Sano, C.; Toshiyoshi, H.; Fujita, H.
2016-11-01
We propose a new type of vibrational energy harvester with an electric double layer (EDL) electrets. Instead of using any external bias-voltage source or dielectric layer on top of the metal electrode to sustain EDL, we succeed to anchor the ions to polymer network to form the EDL electrets. By changing contact area between the EDL electrets and the electrode, large electric current is generated in the circuit. Owing to extremely large capacitance of the EDL electret, vibrational energy harvesters have the unique capability to leverage the high- density charge accumulation to the electrode and obtained current density becomes as high as 200 μA/cm2 with output voltage of 1V even with low frequency vibrations as low as 1 Hz.
Pradhan, G. B.; Juanes-Marcos, J. C.; Balakrishnan, N.; Kendrick, Brian K.
2013-11-21
Quantum scattering calculations are reported for state-to-state vibrational relaxation and reactive scattering in O + OH(v = 2 − 3, j = 0) collisions on the electronically adiabatic ground state {sup 2}A′′ potential energy surface of the HO{sub 2} molecule. The time-independent Schrödinger equation in hyperspherical coordinates is solved to determine energy dependent probabilities and cross sections over collision energies ranging from ultracold to 0.35 eV and for total angular momentum quantum number J = 0. A J-shifting approximation is then used to compute initial state selected reactive rate coefficients in the temperature range T = 1 − 400 K. Results are found to be in reasonable agreement with available quasiclassical trajectory calculations. Results indicate that rate coefficients for O{sub 2} formation increase with increasing the OH vibrational level except at low and ultralow temperatures where OH(v = 0) exhibits a slightly different trend. It is found that vibrational relaxation of OH in v = 2 and v = 3 vibrational levels is dominated by a multi-quantum process.
NASA Technical Reports Server (NTRS)
Mckenzie, R. L.
1976-01-01
A semiclassical collision model is applied to the study of energy transfer rates between a vibrationally excited diatomic molecule and a structureless atom. The molecule is modeled as an anharmonic oscillator with a multitude of dynamically coupled vibrational states. Three main aspects in the prediction of vibrational energy transfer rates are considered. The applicability of the semiclassical model to an anharmonic oscillator is first evaluated for collinear encounters. Second, the collinear semiclassical model is applied to obtain numerical predictions of the vibrational energy transfer rate dependence on the initial vibrational state quantum number. Thermally averaged vibration-translation rate coefficients are predicted and compared with CO-He experimental values for both ground and excited initial states. The numerical model is also used as a basis for evaluating several less complete but analytic models. Third, the role of rational motion in the dynamics of vibrational energy transfer is examined. A three-dimensional semiclassical collision model is constructed with coupled rotational motion included. Energy transfer within the molecule is shown to be dominated by vibration-rotation transitions with small changes in angular momentum. The rates of vibrational energy transfer in molecules with rational frequencies that are very small in comparison to their vibrational frequency are shown to be adequately treated by the preceding collinear models.
A two-dimensional broadband vibration energy harvester using magnetoelectric transducer
Yang, Jin Wen, Yumei; Li, Ping; Yue, Xihai; Yu, Qiangmo; Bai, Xiaoling
2013-12-09
In this study, a magnetoelectric vibration energy harvester was demonstrated, which aims at addressing the limitations of the existing approaches in single dimensional operation with narrow working bandwidth. A circular cross-section cantilever rod, not a conventional thin cantilever beam, was adopted to extract vibration energy in arbitrary in-plane motion directions. The magnetic interaction not only resulted in a nonlinear motion of the rod with increased frequency bandwidth, but also contributed to a multi-mode motion to exhibit double power peaks. In energy harvesting with in-plane directions, it showed a maximum bandwidth of 4.4 Hz and power of 0.59 mW, with acceleration of 0.6 g (with g = 9.8 m s{sup −2})
Saffar, Saber; Abdullah, Amir
2014-03-01
Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach.
DEAP-based energy harvesting using vortex-induced vibrations
NASA Astrophysics Data System (ADS)
Hoffstadt, Thorben; Heinze, Robert; Wahl, Tim; Kameier, Frank; Maas, Jürgen
2014-03-01
Generators based on dielectric electroactive polymers (DEAP) convert mechanical strain energy into electrical field energy. In order to harvest renewable energy from ambient sources adequate generator setups have to be developed. Thus, in this contribution a DEAP generator is presented which uses periodic vortex induced vibration of a circular cylinder as excitation mechanism, by which e.g. Flow energy of a wind or water current can be converted. For this purpose a novel generator design consisting of a cylinder that is elastically mounted on DEAP material is presented. Since the effect of vortex induced vibrations depends on the stiffness and damping of the utilized generator's eigenmode, a method to adapt both via the electrostatic pressure and energy conversion is proposed. After the validation of the general functionality of the novel generator design, analyses concerning the control of the overall harvester are carried out.
Heavy atom vibrational modes and low-energy vibrational autodetachment in nitromethane anions
Thompson, Michael C.; Weber, J. Mathias; Baraban, Joshua H.; Matthews, Devin A.; Stanton, John F.
2015-06-21
We report infrared spectra of nitromethane anion, CH{sub 3}NO{sub 2}{sup −}, in the region 700–2150 cm{sup −1}, obtained by Ar predissociation spectroscopy and electron detachment spectroscopy. The data are interpreted in the framework of second-order vibrational perturbation theory based on coupled-cluster electronic structure calculations. The modes in the spectroscopic region studied here are mainly based on vibrations involving the heavier atoms; this work complements earlier studies on nitromethane anion that focused on the CH stretching region of the spectrum. Electron detachment begins at photon energies far below the adiabatic electron affinity due to thermal population of excited vibrational states.
Nesbitt, D.J. |; Field, R.W.
1996-08-01
A pedagogical overview of intramolecular vibrational redistribution (IVR) phenomena in vibrationally excited molecules is presented. In the interest of focus and simplicity, the topics covered deal primarily with IVR in the ground electronic state, relying on examples from the literature to illustrate key points. The experimental topics discussed attempt to sample systematically three different energy regimes on the full potential surface corresponding to (i) `low`, e.g., moderate- to high-resolution vibrational spectroscopies, (ii) `intermediate`, e.g., stimulated emission pumping and high overtone spectroscopies, and (iii) `high`, e.g., photofragment/predissociation dynamical spectroscopies. The interplay between experiment and theory is highlighted here because it has facilitated enormous advances in the field over the past decade. 183 refs., 13 figs., 2 tabs.
Magma energy for power generation
Dunn, J.C.
1987-01-01
Thermal energy contained in crustal magma bodies represents a large potential resource for the US and magma generated power could become a viable alternative in the future. Engineering feasibility of the magma energy concept is being investigated as part of the Department of Energy's Geothermal Program. This current project follows a seven-year Magma Energy Research Project where scientific feasibility of the concept was concluded.
NASA Astrophysics Data System (ADS)
Montanini, Roberto; Quattrocchi, Antonino
2016-06-01
A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d31 mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.
NASA Astrophysics Data System (ADS)
Lin, Zhiming; Chen, Jun; Li, Xiaoshi; Li, Jun; Liu, Jun; Awais, Qasim; Yang, Jin
2016-12-01
Vibration, widely existing in an ambient environment with a variety of forms and wide-range of scales, recently becomes an attractive target for energy harvesting. However, its time-varying directions and frequencies render a lack of effective energy technology to scavenge it. Here, we report a rationally designed nonlinear magnetoelectric generator for broadband and multi-directional vibration energy harvesting. By using a stabilized three-dimensional (3D) magnetic interaction and spring force, the device working bandwidth was largely broadened, which was demonstrated both experimentally and theoretically. The multidirectional vibration energy harvesting was enabled by three identical suspended springs with equal intersection angles, which are all connected to a cylindrical magnet. Numerical simulations and experimental results show that the nonlinear harvester can sustain large-amplitude oscillations over a wide frequency range, and it can generate power efficiently in an arbitrary direction. Moreover, the experimental data suggest that the proposed nonlinear energy harvester has the potential to scavenge vibrational energy over a broad range of ambient frequencies in 3D space.
Simultaneous Vibration Suppression and Energy Harvesting
2013-08-15
Computational Edition, Thompson International, Florence, KY. Bilgen, Onur, Aerodynamic and Electromechanical Design , Modeling and Implementation of...Transducers: Analysis and Design Based on the Electromechanical Impedance” Part V (Chapter 28) Smart Sensors for Industrial Applications, Ed K...Brazil, March 13th - March 18th, 2011. (Keynote Address) Inman, D. J., 2011, “Nonlinear Considerations in Energy Harvesting,” EPSRC Energy
Importance of Atomic Contacts in Vibrational Energy Flow in Proteins.
Kondoh, Masato; Mizuno, Misao; Mizutani, Yasuhisa
2016-06-02
Vibrational energy flow in proteins was studied by monitoring the time-resolved anti-Stokes ultraviolet resonance Raman scattering of three myoglobin mutants in which a Trp residue substitutes a different amino acid residue near heme. The anti-Stokes Raman intensities of the Trp residue in the three mutants increased with similar rates after depositing excess vibrational energy at heme, despite the difference in distance between heme and each substituted Trp residue along the main chain of the protein. This indicates that vibrational energy is not transferred through the main chain of the protein but rather through atomic contacts between heme and the Trp residue. Distinct differences were observed in the amplitude of the band intensity change between the Trp residues at different positions, and the amplitude of the band intensity change exhibits a correlation with the extent of exposure of the Trp residue to solvent water. This correlation indicates that atomic contacts between an amino acid residue and solvent water play an important role in vibrational energy flow in a protein.
Two-dimensional resonance frequency tuning approach for vibration-based energy harvesting
NASA Astrophysics Data System (ADS)
Dong, Lin; Prasad, M. G.; Fisher, Frank T.
2016-06-01
Vibration-based energy harvesting seeks to convert ambient vibrations to electrical energy and is of interest for, among other applications, powering the individual nodes of wireless sensor networks. Generally it is desired to match the resonant frequencies of the device to the ambient vibration source to optimize the energy harvested. This paper presents a two-dimensionally (2D) tunable vibration-based energy harvesting device via the application of magnetic forces in two-dimensional space. These forces are accounted for in the model separately, with the transverse force contributing to the transverse stiffness of the system while the axial force contributes to a change in axial stiffness of the beam. Simulation results from a COMSOL magnetostatic 3D model agree well with the analytical model and are confirmed with a separate experimental study. Furthermore, analysis of the three possible magnetization orientations between the fixed and tuning magnets shows that the transverse parallel magnetization orientation is the most effective with regards to the proposed 2D tuning approach. In all cases the transverse stiffness term is in general significantly larger than the axial stiffness contribution, suggesting that from a tuning perspective it may be possible to use these stiffness contributions for coarse and fine frequency tuning, respectively. This 2D resonant frequency tuning approach extends earlier 1D approaches and may be particularly useful in applications where space constraints impact the available design space of the energy harvester.
Wu, Jiang; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro
2016-07-01
A method for measuring the mechanical quality factor (Q factor) of materials in large-amplitude flexural vibrations was devised on the basis of the original definition of the Q factor. The Q factor, the ratio of the reactive energy to the dissipated energy, was calculated from the vibration velocity distribution. The bar thickness was selected considering the effect of the thickness on the estimation error. In the experimental setup, a 1-mm-thick polymer-based bar was used as a sample and fixed on the top of a longitudinal transducer. Using transducers of different lengths, flexural waves in the frequency range of 20-90kHz were generated on the bar. The vibration strain in the experiment reached 0.06%. According to the Bernoulli-Euler model, the reactive energy and dissipated energy were estimated from the vertical velocity distribution on the bar, and the Q factors were measured as the driving frequency and strain were varied. The experimental results showed that the Q factors decrease as the driving frequencies and strains increase. At a frequency of 28.30kHz, the Q factor of poly(phenylene sulfide) (PPS) reached approximately 460 when the strain was smaller than 0.005%. PPS exhibited a much higher Q factor than the other tested polymers, which implies that it is a potentially applicable material as the elastomer for high-power ultrasonic devices.
Minimization of the vibration energy of thin-plate structure
NASA Technical Reports Server (NTRS)
Inoue, Katsumi; Townsend, Dennis P.; Coy, John J.
1992-01-01
An optimization method is proposed to reduce the vibration of thin plate structures. The method is based on a finite element shell analysis, a modal analysis, and a structural optimization method. In the finite element analysis, a triangular shell element with 18 dof is used. In the optimization, the overall vibration energy of the structure is adopted as the objective function, and it is minimized at the given exciting frequency by varying the thickness of the elements. The technique of modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variables. The sensitivity is represented by the sensitivities of both eigenvalues and eigenvectors. The optimum value is computed by the gradient projection method and a unidimensional search procedure under the constraint condition of constant weight. A computer code, based on the proposed method, is developed and is applied to design problems using a beam and a plate as test cases. It is confirmed that the vibration energy is reduced at the given exciting frequency. For the beam excited by a frequency slightly less than the fundamental natural frequency, the optimized shape is close to the beam of uniform strength.
Maximum power point tracking for optimizing energy harvesting process
NASA Astrophysics Data System (ADS)
Akbari, S.; Thang, P. C.; Veselov, D. S.
2016-10-01
There has been a growing interest in using energy harvesting techniques for powering wireless sensor networks. The reason for utilizing this technology can be explained by the sensors limited amount of operation time which results from the finite capacity of batteries and the need for having a stable power supply in some applications. Energy can be harvested from the sun, wind, vibration, heat, etc. It is reasonable to develop multisource energy harvesting platforms for increasing the amount of harvesting energy and to mitigate the issue concerning the intermittent nature of ambient sources. In the context of solar energy harvesting, it is possible to develop algorithms for finding the optimal operation point of solar panels at which maximum power is generated. These algorithms are known as maximum power point tracking techniques. In this article, we review the concept of maximum power point tracking and provide an overview of the research conducted in this area for wireless sensor networks applications.
NASA Astrophysics Data System (ADS)
Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.
2014-11-01
Current commercial wireless tire pressure monitoring systems (TPMS) require a battery as electrical power source. The battery limits the lifetime of the TPMS. This limit can be circumvented by replacing the battery by a vibration energy harvester. Autonomous wireless TPMS powered by MEMS electret based vibration energy harvester have been demonstrated. A remaining technical challenge to attain the grade of commercial product with these autonomous TPMS is the mechanical reliability of the MEMS harvester. It should survive the harsh conditions imposed by the tire environment, particularly in terms of mechanical shocks. As shown in this article, our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, several types of shock absorbing structures are investigated. With the best proposed solution, the shock resilience of the harvesters is brought above 2500 g.
Shoe-mounted vibration energy harvester of PZT piezoelectric thin films on metal foils
NASA Astrophysics Data System (ADS)
Nishi, T.; Ito, T.; Hida, H.; Kanno, I.
2016-11-01
This paper describes shoe-mounted piezoelectric vibration energy harvesters (PVEHs). The PVEHs were fabricated from Pb(ZrTi)O3 (PZT) thin films which were directly deposited onto Pt/Ti-coated stainless steel foil by rf-magnetron sputtering. We experimentally and theoretically evaluated impulse responses of the PVEHs by applying a simple impulse input on the energy harvesters, typical damped free vibration behaviour was clearly observed, and the output signal was in good agreement with the theoretical value. We measured the output power by applying the impulse input with an optimal load resistance of 33.9 kΩ. The maximum output power was approximately 20 μW, which correspond with the calculated value based on theoretical equation. From these results, the theoretical equation we derived might be helpful for design purposes of the shoe-mounted PVEHs.
Power flow prediction in vibrating systems via model reduction
NASA Astrophysics Data System (ADS)
Li, Xianhui
This dissertation focuses on power flow prediction in vibrating systems. Reduced order models (ROMs) are built based on rational Krylov model reduction which preserve power flow information in the original systems over a specified frequency band. Stiffness and mass matrices of the ROMs are obtained by projecting the original system matrices onto the subspaces spanned by forced responses. A matrix-free algorithm is designed to construct ROMs directly from the power quantities at selected interpolation frequencies. Strategies for parallel implementation of the algorithm via message passing interface are proposed. The quality of ROMs is iteratively refined according to the error estimate based on residual norms. Band capacity is proposed to provide a priori estimate of the sizes of good quality ROMs. Frequency averaging is recast as ensemble averaging and Cauchy distribution is used to simplify the computation. Besides model reduction for deterministic systems, details of constructing ROMs for parametric and nonparametric random systems are also presented. Case studies have been conducted on testbeds from Harwell-Boeing collections. Input and coupling power flow are computed for the original systems and the ROMs. Good agreement is observed in all cases.
Investigation of Vibrational Energy Transfer in Connected Structures
NASA Technical Reports Server (NTRS)
Hwang, C.; Pi, W. S.
1973-01-01
The results are reported of an analytical and experimental investigation on the vibrational energy transfer between connected substructures under random excitation. In the analytical area, the basic foundation and assumptions of the statistical energy analysis (SEA) method, a major tool in random response analysis of structures, were examined and reviewed. A new SEA formulation based on the strong coupling condition of the substructures was carried out and presented. Also presented were the results of vibration energy transfer study based on the wave equations applied to connected structures. In the experimental phase, three simple structural models were fabricated and tested. Additional tests were performed on selected substructures which formed parts of the test models. The test results were presented and evaluated against the analytical data.
NASA Astrophysics Data System (ADS)
Alexander, B. X. S.
Flywheel energy storage has distinct advantages over conventional energy storage methods such as electrochemical batteries. Because the energy density of a flywheel rotor increases quadratically with its speed, the foremost goal in flywheel design is to achieve sustainable high speeds of the rotor. Many issues exist with the flywheel rotor operation at high and varying speeds. A prominent problem is synchronous rotor vibration, which can drastically limit the sustainable rotor speed. In a set of projects, the novel Active Disturbance Rejection Control (ADRC) is applied to various problems of flywheel rotor operation. These applications include rotor levitation, steady state rotation at high speeds and accelerating operation. Several models such as the lumped mass model and distributed three-mass models have been analyzed. In each of these applications, the ADRC has been extended to cope with disturbance, noise, and control effort optimization; it also has been compared to various industry-standard controllers such as PID and PD/observer, and is proven to be superior. The control performance of the PID controller and the PD/observer currently used at NASA Glenn has been improved by as much as an order of magnitude. Due to the universality of the second order system, the results obtained in the rotor vibration problem can be straightforwardly extended to other vibrational systems, particularly, the MEMS gyroscope. Potential uses of a new nonlinear controller, which inherits the ease of use of the traditional PID, are also discussed.
Electromagnetic Vibration Energy Harvester Using Springless Proof Mass and Ferrofluid as a Lubricant
NASA Astrophysics Data System (ADS)
Chae, S. H.; Ju, S.; Choi, Y.; Jun, S.; Park, S. M.; Lee, S.; Lee, H. W.; Ji, C.-H.
2013-12-01
This paper presents an electromagnetic energy harvester using an array of rectangular permanent magnets as springless proof mass and ferrofluid as a lubricating material. Lateral motion of the multi-pole magnet array generates voltage across an array of copper windings formed under the aluminum channel in response to low frequency external vibrations such as human-body-induced motion. A proof-of-concept device has been fabricated and output voltage has been measured at various input frequencies and accelerations provided by a vibration exciter. Device with ferrofluid lubrication generated maximum open-circuit voltage of 0.47V at 3g vibration at 12Hz, which is 8% higher than that of the device without lubricant. Maximum output power of 71.26μW has been obtained at 40.8Ω with the device with ferrofluid lubrication.
Efficiency improvement of a cantilever-type energy harvester using torsional vibration
NASA Astrophysics Data System (ADS)
Kim, In-Ho; Jang, Seon-Jun; Koo, Jeong-Hoi; Jung, Hyung-Jo
2016-04-01
In this paper, a piezoelectric vibrational energy harvester utilizing coupled bending and torsional vibrations is investigated. The proposed system consists of a cantilever-type substrate covered by the piezoelectric ceramic and a proof mass which is perpendicularly connected to the free end of the cantilever beam by a rigid bar. While the natural frequency and output voltage of the conventional system are affected by bending deformation of the piezoelectric plate, the proposed system makes use of its twisting deformation. The natural frequency of the device can be significantly decreased by manipulating the location of the proof mass on the rigid bar. In order to validate the performance of the proposed energy harvester, numerical simulations and vertical shaker tests are carried out. It is demonstrated that the proposed energy harvester can shift down its resonant frequency considerably and generate much higher output power than the conventional system. It is, therefore, concluded that the proposed energy harvester utilizing the coupled bending and torsional vibrations can be effectively applied to low-frequency vibration situations.
Influence of combined fundamental potentials in a nonlinear vibration energy harvester
Podder, Pranay; Mallick, Dhiman; Amann, Andreas; Roy, Saibal
2016-01-01
Ambient mechanical vibrations have emerged as a viable energy source for low-power wireless sensor nodes aiming the upcoming era of the ‘Internet of Things’. Recently, purposefully induced dynamical nonlinearities have been exploited to widen the frequency spectrum of vibration energy harvesters. Here we investigate some critical inconsistencies between the theoretical formulation and applications of the bistable Duffing nonlinearity in vibration energy harvesting. A novel nonlinear vibration energy harvesting device with the capability to switch amidst individually tunable bistable-quadratic, monostable-quartic and bistable-quartic potentials has been designed and characterized. Our study highlights the fundamentally different large deflection behaviors of the theoretical bistable-quartic Duffing oscillator and the experimentally adapted bistable-quadratic systems, and underlines their implications in the respective spectral responses. The results suggest enhanced performance in the bistable-quartic potential in comparison to others, primarily due to lower potential barrier and higher restoring forces facilitating large amplitude inter-well motion at relatively lower accelerations. PMID:27874033
Influence of combined fundamental potentials in a nonlinear vibration energy harvester
NASA Astrophysics Data System (ADS)
Podder, Pranay; Mallick, Dhiman; Amann, Andreas; Roy, Saibal
2016-11-01
Ambient mechanical vibrations have emerged as a viable energy source for low-power wireless sensor nodes aiming the upcoming era of the ‘Internet of Things’. Recently, purposefully induced dynamical nonlinearities have been exploited to widen the frequency spectrum of vibration energy harvesters. Here we investigate some critical inconsistencies between the theoretical formulation and applications of the bistable Duffing nonlinearity in vibration energy harvesting. A novel nonlinear vibration energy harvesting device with the capability to switch amidst individually tunable bistable-quadratic, monostable-quartic and bistable-quartic potentials has been designed and characterized. Our study highlights the fundamentally different large deflection behaviors of the theoretical bistable-quartic Duffing oscillator and the experimentally adapted bistable-quadratic systems, and underlines their implications in the respective spectral responses. The results suggest enhanced performance in the bistable-quartic potential in comparison to others, primarily due to lower potential barrier and higher restoring forces facilitating large amplitude inter-well motion at relatively lower accelerations.
NASA Astrophysics Data System (ADS)
Perfetto, S.; Rohlfing, J.; Infante, F.; Mayer, D.; Herold, S.
2016-09-01
Piezoelectric transducers can be used to harvest electrical energy from structural vibrations in order to power continuously operating condition monitoring systems local to where they operate. However, excessive vibrations can compromise the safe operation of mechanical systems. Therefore, absorbers are commonly used to control vibrations. With an integrated device, the mechanical energy that otherwise would be dissipated can be converted via piezoelectric transducers. Vibration absorbers are designed to have high damping factors. Hence, the integration of transducers would lead to a low energy conversion. Efficient energy harvesters usually have low damping capabilities; therefore, they are not effective for vibration suppression. Thus, the design of an integrated device needs to consider the two conflicting requirements on the damping. This study focuses on the development of a laboratory test rig with a host structure and a vibration absorber with tunable damping via an active relative velocity feedback. A voice coil actuator is used for this purpose. To overcome the passive damping effects of the back electromagnetic force a novel voltage feedback control is proposed, which has been validated both in simulation and experimentally. The aim of this study is to have a test rig ready for the introduction of piezo-transducers and available for future experimental evaluations of the damping effect on the effectiveness of vibration reduction and energy harvesting efficiency.
Accurate ab initio vibrational energies of methyl chloride
Owens, Alec; Yurchenko, Sergei N.; Yachmenev, Andrey; Tennyson, Jonathan; Thiel, Walter
2015-06-28
Two new nine-dimensional potential energy surfaces (PESs) have been generated using high-level ab initio theory for the two main isotopologues of methyl chloride, CH{sub 3}{sup 35}Cl and CH{sub 3}{sup 37}Cl. The respective PESs, CBS-35{sup HL}, and CBS-37{sup HL}, are based on explicitly correlated coupled cluster calculations with extrapolation to the complete basis set (CBS) limit, and incorporate a range of higher-level (HL) additive energy corrections to account for core-valence electron correlation, higher-order coupled cluster terms, scalar relativistic effects, and diagonal Born-Oppenheimer corrections. Variational calculations of the vibrational energy levels were performed using the computer program TROVE, whose functionality has been extended to handle molecules of the form XY {sub 3}Z. Fully converged energies were obtained by means of a complete vibrational basis set extrapolation. The CBS-35{sup HL} and CBS-37{sup HL} PESs reproduce the fundamental term values with root-mean-square errors of 0.75 and 1.00 cm{sup −1}, respectively. An analysis of the combined effect of the HL corrections and CBS extrapolation on the vibrational wavenumbers indicates that both are needed to compute accurate theoretical results for methyl chloride. We believe that it would be extremely challenging to go beyond the accuracy currently achieved for CH{sub 3}Cl without empirical refinement of the respective PESs.
NASA Astrophysics Data System (ADS)
Chuntonov, Lev; Peskin, Uri
2017-01-01
Vibrational energy transfer driven by anharmonicity is the major mechanism of energy dissipation in polyatomic molecules and in molecules embedded in condensed phase environment. Energy transfer pathways are sensitive to the particular intra-molecular structure as well as to specific interactions between the molecule and its environment, and their identification is a challenging many-body problem. This work introduces a theoretical approach which enables to identify the dominant pathways for specified initial excitations, by screening the different possible relaxation channels. For each channel, the many-body Hamiltonian is mapped onto a respective all-vibrational Spin-Boson Hamiltonian, expressed in terms of the harmonic frequencies and the anharmonic coupling parameters obtained from the electronic structure of the molecule in its environment. A focus is given on the formulation of the relaxation rates when different limits of perturbation theory apply. In these cases the proposed Spin-Boson Screening approach becomes especially powerful.
State-of-the-art in vibration-based electrostatic energy harvesting
NASA Astrophysics Data System (ADS)
Ullah Khan, Farid; Usman Qadir, Muhammad
2016-10-01
Recently, embedded systems and wireless sensor nodes have been gaining importance. For operating these devices several vibration-based energy harvesters have been successfully developed and reported, such as piezoelectric, electromagnetic, and electrostatic energy harvesters (EEHs). This paper presents the state-of-the-art in the field of vibration-based EEHs. Mainly, two types of EEHs, electret-free and electret-based, are reported in the literature. The developed EEHs are mostly of the centimeter scale. These energy harvesters, with resonant frequencies ranging from 2 Hz to 1.7 kHz, when subjected to excitation on the order of 0.25 g to 14.2 g, generate power that ranges from 0.46 nW to 2.1 mW.
Resonant vibrational excitation of CO by low-energy electrons
Poparic, G. B.; Belic, D. S.; Vicic, M. D.
2006-06-15
Electron impact vibrational excitation of the CO molecule, via the {sup 2}{pi} resonance, in the 0-4 eV energy region has been investigated. The energy dependence of the resonant excitation of the first ten vibrational levels, v=1 to v=10, has been measured by use of a crossed-beams double trochoidal electron spectrometer. Obtained relative differential cross sections are normalized to the absolute values. Integral cross sections are determined by using our recent results on scattered electrons angular distributions, which demonstrate clear p-partial wave character of this resonance. Substructures appear in the {sup 2}{pi} resonant excitation of the CO molecule which have not been previously observed.
Exploring the vibrational fingerprint of the electronic excitation energy via molecular dynamics
Deyne, Andy Van Yperen-De; Pauwels, Ewald; Ghysels, An; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen; De Meyer, Thierry; De Clerck, Karen
2014-04-07
A Fourier-based method is presented to relate changes of the molecular structure during a molecular dynamics simulation with fluctuations in the electronic excitation energy. The method implies sampling of the ground state potential energy surface. Subsequently, the power spectrum of the velocities is compared with the power spectrum of the excitation energy computed using time-dependent density functional theory. Peaks in both spectra are compared, and motions exhibiting a linear or quadratic behavior can be distinguished. The quadratically active motions are mainly responsible for the changes in the excitation energy and hence cause shifts between the dynamic and static values of the spectral property. Moreover, information about the potential energy surface of various excited states can be obtained. The procedure is illustrated with three case studies. The first electronic excitation is explored in detail and dominant vibrational motions responsible for changes in the excitation energy are identified for ethylene, biphenyl, and hexamethylbenzene. The proposed method is also extended to other low-energy excitations. Finally, the vibrational fingerprint of the excitation energy of a more complex molecule, in particular the azo dye ethyl orange in a water environment, is analyzed.
NASA Technical Reports Server (NTRS)
Inoue, Katsumi; Krantz, Timothy L.
1995-01-01
While the vibration analysis of gear systems has been developed, a systematic approach to the reduction of gearbox vibration has been lacking. The technique of reducing vibration by shifting natural frequencies is proposed here for gearboxes and other thin-plate structures using the theories of finite elements, modal analysis, and optimization. A triangular shell element with 18 degrees of freedom is developed for structural and dynamic analysis. To optimize, the overall vibration energy is adopted as the objective function to be minimized at the excitation frequency by varying the design variable (element thickness) under the constraint of overall constant weight. Modal analysis is used to determine the sensitivity of the vibration energy as a function of the eigenvalues and eigenvectors. The optimum design is found by the gradient projection method and a unidimensional search procedure. By applying the computer code to design problems for beams and plates, it was verified that the proposed method is effective in reducing vibration energy. The computer code is also applied to redesign the NASA Lewis gear noise rig test gearbox housing. As one example, only the shape of the top plate is varied, and the vibration energy levels of all the surfaces are reduced, yielding an overall reduction of 1/5 compared to the initial design. As a second example, the shapes of the top and two side plates are varied to yield an overall reduction in vibration energy of 1/30.
NASA Astrophysics Data System (ADS)
Halim, Miah A.; Park, Jae Y.
2014-03-01
We present a non-resonant, frequency up-converted electromagnetic energy harvester that generates significant power from human-body-induced vibration, e.g., hand-shaking. Upon excitation, a freely movable non-magnetic ball within a cylinder periodically hits two magnets suspended on two helical compression springs located at either ends of the cylinder, allowing those to vibrate with higher frequencies. The device parameters have been designed based on the characteristics of human hand-shaking vibration. A prototype has been developed and tested both by vibration exciter (for non-resonance test) and by manual hand-shaking. The fabricated device generated 110 μW average power with 15.4 μW cm-3 average power density, while the energy harvester was mounted on a smart phone and was hand-shaken, indicating its ability in powering portable hand-held smart devices from low frequency (<5 Hz) vibrations.
Optimal energy harvesting from vortex-induced vibrations of cables
NASA Astrophysics Data System (ADS)
Antoine, G. O.; de Langre, E.; Michelin, S.
2016-11-01
Vortex-induced vibrations (VIV) of flexible cables are an example of flow-induced vibrations that can act as energy harvesting systems by converting energy associated with the spontaneous cable motion into electricity. This work investigates the optimal positioning of the harvesting devices along the cable, using numerical simulations with a wake oscillator model to describe the unsteady flow forcing. Using classical gradient-based optimization, the optimal harvesting strategy is determined for the generic configuration of a flexible cable fixed at both ends, including the effect of flow forces and gravity on the cable's geometry. The optimal strategy is found to consist systematically in a concentration of the harvesting devices at one of the cable's ends, relying on deformation waves along the cable to carry the energy towards this harvesting site. Furthermore, we show that the performance of systems based on VIV of flexible cables is significantly more robust to flow velocity variations, in comparison with a rigid cylinder device. This results from two passive control mechanisms inherent to the cable geometry: (i) the adaptability to the flow velocity of the fundamental frequencies of cables through the flow-induced tension and (ii) the selection of successive vibration modes by the flow velocity for cables with gravity-induced tension.
Vortex-induced vibrations mitigation through a nonlinear energy sink
NASA Astrophysics Data System (ADS)
Dai, H. L.; Abdelkefi, A.; Wang, L.
2017-01-01
The passive suppression mechanism of the vortex-induced vibrations (VIV) of the cylinder by means of an essentially nonlinear element, the nonlinear energy sink (NES) is investigated. The flow-induced loads on the cylinder are modeled using a prevalent van der Pol oscillator which is experimentally validated, coupling to the structural vibrations in the presence of the NES structure. Based on the coupled nonlinear governing equations of motion, the performed analysis indicates that the mass and damping of NES have significant effects on the coupled frequency and damping of the aero-elastic system, leading to the shift of synchronization region and mitigation of vibration responses. It is demonstrated that the coupled system of flow-cylinder-NES behaves resonant interactions, showing periodic, aperiodic, and multiple stable responses which depend on the values of the NES parameters. In addition, it is found that the occurrence of multiple stable responses can enhance the nonlinear energy pumping effect, resulting in the increment of transferring energy from the flow via the cylinder to the NES, which is related to the essential nonlinearity of the sink stiffness. This results in a significant reduction in the VIV amplitudes of the primary circular cylinder for appropriate NES parameter values.
Optimal energy harvesting from vortex-induced vibrations of cables.
Antoine, G O; de Langre, E; Michelin, S
2016-11-01
Vortex-induced vibrations (VIV) of flexible cables are an example of flow-induced vibrations that can act as energy harvesting systems by converting energy associated with the spontaneous cable motion into electricity. This work investigates the optimal positioning of the harvesting devices along the cable, using numerical simulations with a wake oscillator model to describe the unsteady flow forcing. Using classical gradient-based optimization, the optimal harvesting strategy is determined for the generic configuration of a flexible cable fixed at both ends, including the effect of flow forces and gravity on the cable's geometry. The optimal strategy is found to consist systematically in a concentration of the harvesting devices at one of the cable's ends, relying on deformation waves along the cable to carry the energy towards this harvesting site. Furthermore, we show that the performance of systems based on VIV of flexible cables is significantly more robust to flow velocity variations, in comparison with a rigid cylinder device. This results from two passive control mechanisms inherent to the cable geometry: (i) the adaptability to the flow velocity of the fundamental frequencies of cables through the flow-induced tension and (ii) the selection of successive vibration modes by the flow velocity for cables with gravity-induced tension.
Energy Industry Powers CTE Program
ERIC Educational Resources Information Center
Khokhar, Amy
2012-01-01
Michael Fields is a recent graduate of Buckeye Union High School in Buckeye, Arizona. Fields is enrolled in the Estrella Mountain Community College (EMCC) Get Into Energy program, which means he is well on his way to a promising career. Specializing in power plant technology, in two years he will earn a certificate that will all but guarantee a…
NASA Astrophysics Data System (ADS)
Lumentut, M. F.; Howard, I. M.
2013-03-01
Power harvesters that extract energy from vibrating systems via piezoelectric transduction show strong potential for powering smart wireless sensor devices in applications of health condition monitoring of rotating machinery and structures. This paper presents an analytical method for modelling an electromechanical piezoelectric bimorph beam with tip mass under two input base transverse and longitudinal excitations. The Euler-Bernoulli beam equations were used to model the piezoelectric bimorph beam. The polarity-electric field of the piezoelectric element is excited by the strain field caused by base input excitation, resulting in electrical charge. The governing electromechanical dynamic equations were derived analytically using the weak form of the Hamiltonian principle to obtain the constitutive equations. Three constitutive electromechanical dynamic equations based on independent coefficients of virtual displacement vectors were formulated and then further modelled using the normalised Ritz eigenfunction series. The electromechanical formulations include both the series and parallel connections of the piezoelectric bimorph. The multi-mode frequency response functions (FRFs) under varying electrical load resistance were formulated using Laplace transformation for the multi-input mechanical vibrations to provide the multi-output dynamic displacement, velocity, voltage, current and power. The experimental and theoretical validations reduced for the single mode system were shown to provide reasonable predictions. The model results from polar base excitation for off-axis input motions were validated with experimental results showing the change to the electrical power frequency response amplitude as a function of excitation angle, with relevance for practical implementation.
NASA Astrophysics Data System (ADS)
Miller, Lindsay Margaret
Wireless sensor networks (WSNs) have the potential to transform engineering infrastructure, manufacturing, and building controls by allowing condition monitoring, asset tracking, demand response, and other intelligent feedback systems. A wireless sensor node consists of a power supply, sensor(s), power conditioning circuitry, radio transmitter and/or receiver, and a micro controller. Such sensor nodes are used for collecting and communicating data regarding the state of a machine, system, or process. The increasing demand for better ways to power wireless devices and increase operation time on a single battery charge drives an interest in energy harvesting research. Today, wireless sensor nodes are typically powered by a standard single-charge battery, which becomes depleted within a relatively short timeframe depending on the application. This introduces tremendous labor costs associated with battery replacement, especially when there are thousands of nodes in a network, the nodes are remotely located, or widely-distributed. Piezoelectric vibration energy harvesting presents a potential solution to the problems associated with too-short battery life and high maintenance requirements, especially in industrial environments where vibrations are ubiquitous. Energy harvester designs typically use the harvester to trickle charge a rechargeable energy storage device rather than directly powering the electronics with the harvested energy. This allows a buffer between the energy harvester supply and the load where energy can be stored in a "tank". Therefore, the harvester does not need to produce the full required power at every instant to successfully power the node. In general, there are tens of microwatts of power available to be harvested from ambient vibrations using micro scale devices and tens of milliwatts available from ambient vibrations using meso scale devices. Given that the power requirements of wireless sensor nodes range from several microwatts to about one
Highly piezoelectric MgZr co-doped aluminum nitride-based vibrational energy harvesters.
Minh, Le Van; Hara, Motoaki; Yokoyama, Tsuyoshi; Nishihara, Tokihiro; Ueda, Masanori; Kuwano, Hiroki
2015-11-01
The first MgZr co-doped AlN-based vibrational energy harvester (VEH) is presented. (MgZr)AlN, which is a new class of doped AlN, provides high piezoelectricity and cost advantage. Using 13%-(MgZr)-doped AlN for micromachined VEHs, maximum output power of 1.3 μW was achieved with a Q-factor of 400 when resonant frequency, vibration acceleration, load resistance were 792 Hz, 8 m/s(2), and 1.1 MΩ, respectively. Normalized power density was 8.1 kW·g(-2)·m(-3). This was one of the highest values among the currently available piezoelectric VEHs.
NASA Astrophysics Data System (ADS)
Takiguchi, T.; Sasaki, T.; Nakajima, T.; Yamaura, S.; Sekiguchi, T.; Shoji, S.
2014-11-01
Basic research of MEMS based micro devices for vibration energy harvesting using vinylidene fluoride / trifluoroethylene (VDF/TrFE) copolymer thin film was investigated. The VDF/TrFE copolymer thin film was formed by spin coating. Thickness of VDF/TrFE copolymer thin film was ranged from 375 nm to 2793 nm. Impedance of VDF/TrFE copolymer thin film was measured by LCR meter. Thin film in each thickness was fully poled by voltage based on C-V characteristics result. Generated power of the devices under applied vibration was observed by an oscilloscope. When the film thickness is 2793 nm, the generated power was about 0.815 μJ.
NASA Astrophysics Data System (ADS)
Ben Ouanes, M. A.; Lu, Y.; Samaali, H.; Basset, P.; Najar, F.
2016-11-01
In this work, we demonstrate that the use of self-synchronized mechanical switches in replacement of diodes into electrostatic vibration energy harvesters (e-VEH) can lead to better power generation. Indeed, mechanical switches have the advantage of no leakage current and no threshold voltage. As a proof of concept, we use the Bennet's doubler electrostatic generator. The proposed e-VEH is composed of two variable capacitors triggered by a central electrode taken as an inertial mass. Ambient vibrations induce inertial forces on the central electrode, as a result a voltage doubling is obtained at each operating cycle. The mechanical switches are directly fixed to the moving electrode. In addition, no dedicated pre-charge is required: the system starts with ambient electrical charges. The device is fabricated and tested under harmonic motion. A comparison between the proposed design and those using diodes under the same operating conditions shows an experimental direct increase of the harvested electrical power of around 28%.
NASA Astrophysics Data System (ADS)
Ung, Chandarin; Moss, Scott D.; Chiu, Wing K.; Payne, Owen R.; Vandewater, Luke A.; Galea, Steve C.
2015-04-01
The dominant vibration frequencies exhibited by heavy haul railcars (operating in remote regions of Western Australia) are found to be 5.8 Hz and 14.6 Hz for loaded and unloaded trips respectively. This paper describes the in-service demonstration of two electromagnetic vibration energy harvesting technologies designed to generated power from these railcar vibrations: (i) a coupled two-degree of freedom (2-DoF) device capable of capturing both dominant frequencies of the railcar and (ii) a hybrid rotary-translational harvester device based on a magnetic sphere capable of harvesting from ̴ 6 Hz. The two devices were laboratory tested prior to mounting on a heavy railcar for in-service demonstration. Within the laboratory the coupled 2-DoF device was found to produce a maximum peak output power of 350 mW from 0.4 g root-mean-square (rms) acceleration at 15 Hz and 230 mW from 6 Hz. The hybrid rotary-translational device based on an oscillating magnetic sphere can produce ̴138 mW from host vibration of 0.4 g rms at 5.4 Hz. This paper will discuss and compare the performance of the two prototypes, both within the laboratory and during the in-service demonstration on a heavy heal railcar.
NASA Astrophysics Data System (ADS)
Abed, I.; Kacem, N.; Bouhaddi, N.; Bouazizi, M. L.
2016-02-01
We propose a multi-modal vibration energy harvesting approach based on arrays of coupled levitated magnets. The equations of motion which include the magnetic nonlinearity and the electromagnetic damping are solved using the harmonic balance method coupled with the asymptotic numerical method. A multi-objective optimization procedure is introduced and performed using a non-dominated sorting genetic algorithm for the cases of small magnet arrays in order to select the optimal solutions in term of performances by bringing the eigenmodes close to each other in terms of frequencies and amplitudes. Thanks to the nonlinear coupling and the modal interactions even for only three coupled magnets, the proposed method enable harvesting the vibration energy in the operating frequency range of 4.6-14.5 Hz, with a bandwidth of 190% and a normalized power of 20.2 {mW} {{cm}}-3 {{{g}}}-2.
Experimental energy harvesting from fluid flow by using two vibrating masses
NASA Astrophysics Data System (ADS)
Nishi, Yoshiki; Fukuda, Kengo; Shinohara, Wataru
2017-04-01
In this study, an experiment was performed to determine how the addition of a second degree of freedom to a vibratory system affects its energy extraction from a surrounding fluid flow. A circular cylinder was submerged underwater and subjected to flow, and another cylinder mounted on springs was inserted between the submerged cylinder and a generator. The experiment results demonstrated that vortex-induced vibration occurred at frequencies that were locked-in to the first and second natural modes for reduced velocity ranges of 5.0-9.0 and greater than 12.0, respectively. The output voltages were particularly high when the vibration frequency was locked-in to that of the second natural mode. It was found that application of energy extraction using a system with two degrees of freedom can widen the range of reduced velocity within which power extraction is effective.
Vibrational energy distribution analysis (VEDA): scopes and limitations.
Jamróz, Michał H
2013-10-01
The principle of operations of the VEDA program written by the author for Potential Energy Distribution (PED) analysis of theoretical vibrational spectra is described. Nowadays, the PED analysis is indispensible tool in serious analysis of the vibrational spectra. To perform the PED analysis it is necessary to define 3N-6 linearly independent local mode coordinates. Already for 20-atomic molecules it is a difficult task. The VEDA program reads the input data automatically from the Gaussian program output files. Then, VEDA automatically proposes an introductory set of local mode coordinates. Next, the more adequate coordinates are proposed by the program and optimized to obtain maximal elements of each column (internal coordinate) of the PED matrix (the EPM parameter). The possibility for an automatic optimization of PED contributions is a unique feature of the VEDA program absent in any other programs performing PED analysis.
Vibrational Energy Distribution Analysis (VEDA): Scopes and limitations
NASA Astrophysics Data System (ADS)
Jamróz, Michał H.
2013-10-01
The principle of operations of the VEDA program written by the author for Potential Energy Distribution (PED) analysis of theoretical vibrational spectra is described. Nowadays, the PED analysis is indispensible tool in serious analysis of the vibrational spectra. To perform the PED analysis it is necessary to define 3N-6 linearly independent local mode coordinates. Already for 20-atomic molecules it is a difficult task. The VEDA program reads the input data automatically from the Gaussian program output files. Then, VEDA automatically proposes an introductory set of local mode coordinates. Next, the more adequate coordinates are proposed by the program and optimized to obtain maximal elements of each column (internal coordinate) of the PED matrix (the EPM parameter). The possibility for an automatic optimization of PED contributions is a unique feature of the VEDA program absent in any other programs performing PED analysis.
ENergy and Power Evaluation Program
1996-11-01
In the late 1970s, national and international attention began to focus on energy issues. Efforts were initiated to design and test analytical tools that could be used to assist energy planners in evaluating energy systems, particularly in developing countries. In 1984, the United States Department of Energy (DOE) commissioned Argonne National Laboratory`s Decision and Information Sciences Division (DIS) to incorporate a set of analytical tools into a personal computer-based package for distribution in developing countries. The package developed by DIS staff, the ENergy and Power Evaluation Program (ENPEP), covers the range of issues that energy planners must face: economic development, energy demand projections, supply-and-demand balancing, energy system expansion, and environmental impact analysis. Following the original DOE-supported development effort, the International Atomic Energy Agency (IAEA), with the assistance from the US Department of State (DOS) and the US Department of Energy (DOE), provided ENPEP training, distribution, and technical support to many countries. ENPEP is now in use in over 60 countries and is an international standard for energy planning tools. More than 500 energy experts have been trained in the use of the entire ENPEP package or some of its modules during the international training courses organized by the IAEA in collaboration with Argonne`s Decision and Information Sciences (DIS) Division and the Division of Educational Programs (DEP). This report contains the ENPEP program which can be download from the internet. Described in this report is the description of ENPEP Program, news, forums, online support and contacts.
NASA Astrophysics Data System (ADS)
Yao, Gang; Wang, Hai; Yang, Chunlai; Wen, Li
2017-03-01
With the increasing development of wireless sensor network (WSN), power supply for WSN nodes had attracted increasing attention, and the energy harvesting system based on Karman vortex street has been widely used in underwater WSN. But the research of the influences of affecting factors towards the energy harvesting system is yet to be completed. So, in this paper, an underwater flow-induced vibration energy harvesting system based on Karman vortex street was proposed and tested. The influence of bluff body geometry and flow velocity towards the performance of the energy harvesting has been researched. The results showed that the output voltage increased as the diameter of bluff body and the water velocity increase. The power generation efficiency was the best when the shape of bluff body was circular.
Apparent Mass and Absorbed Power during Exposure to Whole-Body Vibration and Repeated Shocks
NASA Astrophysics Data System (ADS)
MANSFIELD, N. J.; HOLMLUND, P.; LUNDSTRÖM, R.
2001-11-01
Exposure to mechanical shocks might pose a greater health risk than exposure to continuous vibration. Previous studies have investigated subjective responses, muscle activity or transmission of vibration to the spine or head during shock. If there is a difference between biomechanic responses of the seated body to shocks when compared to continuous vibration, then this may indicate a more, or less, hazardous vibration waveform. This paper presents measurements of apparent mass and absorbed power during exposure to random vibration, repeated shocks and combinations of shocks and random vibration. Eleven male and 13 female subjects were exposed to 15 vibration conditions generated using an electro-dynamic shaker. Subjects were exposed to five 20 s acceleration waveforms with nominally identical power spectra (random vibration, equally spaced shocks, unequally spaced shocks, random combined with equally spaced shocks, random combined with unequally spaced shocks) at each of 0·5, 1·0 and 1·5 m/s2r.m.s. The general shapes of the apparent mass or absorbed power curves were not affected by stimulus type, indicating that the biomechanical response of the body is fundamentally the same when exposed to shocks or random vibration. Two non-linear effects were observed: apparent mass resonance frequencies were slightly higher for exposure to shocks; apparent mass and absorbed power resonance frequencies decreased with increases in vibration magnitude for each stimulus type. It is concluded that the two non-linear mechanisms operate simultaneously: a stiffening effect during exposure to shocks and a softening effect as vibration magnitudes increase. Total absorbed powers were greatest for shock stimuli and least for random vibration.
Air-spaced PDMS piezo-electret cantilevers for vibration energy harvesting
NASA Astrophysics Data System (ADS)
Kachroudi, A.; Basrour, S.; Rufer, L.; Jomni, F.
2016-11-01
This paper reports a design of a new prototype of air-spaced cantilevers made from a micro-structured PDMS piezo-electret material for accelerometer and energy harvesting applications. The test performed on these cantilevers in a sensor mode exhibits a stable sensitivity of 385 mV/g for a frequency ranging from 5 Hz to 200 Hz that encompass most macro-scale vibrations. In the energy harvesting mode, the cantilever generates a power of 103 nW with a load resistance of 217 MΩ.
NASA Astrophysics Data System (ADS)
Ansari, M. H.; Karami, M. Amin
2016-03-01
This paper studies energy harvesting from heartbeat vibrations for powering leadless pacemakers. Unlike traditional pacemakers, leadless pacemakers are implanted inside the heart and the pacemaker is in direct contact with the myocardium. A leadless pacemaker is in the shape of a cylinder. Thus, in order to utilize the available 3-dimensional space for the energy harvester, we choose a fan-folded 3D energy harvester. The proposed device consists of several piezoelectric beams stacked on top of each other. The volume of the energy harvester is 1 cm3 and its dimensions are 2 cm × 0.5 cm × 1 cm. Although high natural frequency is generally a major concern with micro-scale energy harvesters, by utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, we reduced the natural frequency to the desired range. This fan-folded design makes it possible to generate more than 10 μ W of power per cubic centimeter. The proposed device is compatible with Magnetic Resonance Imaging. Although the proposed device is a linear energy harvester, it is relatively insensitive to the heart rate. The natural frequencies and the mode shapes of the device are calculated analytically. The accuracy of the analytical model is verified by experimental investigations. We use a closed loop shaker system to precisely replicate heartbeat vibrations in vitro.
NASA Astrophysics Data System (ADS)
Zhang, Qian; Wang, Yufeng; Zhao, Lurui; Sok Kim, Eun
2016-02-01
This paper presents two microfabrication approaches for multi-layer coils for vibration-energy harvesters. A magnet array is arranged with alternating north- and south-orientation to provide a rapidly changing magnetic field for high electromagnetic energy conversion. Multi-turn spiral coils on silicon wafer are aligned to the magnet array for maximum magnetic flux change. One type of coil is made out of 300 μm-thick copper that is electroplated with silicon mold, and the other is built on 25 μm-thick copper electroplated with photoresist mold. The low resistive coils fabricated by the first approach are integrated in a microfabricated energy harvester of 17 × 7 × 1.7 mm3 (=0.2 cm3) weighing 0.8 g, which generates 14.3 μW power output (into 0.7 Ω load) from vibration amplitude of 6 μm at 250 Hz. The latter approach is used to make a 1080-turn coil for a microfabricated electromagnetic energy harvester with magnet array and plastic spring. Though the size and weight of the harvester are only 44 × 20 × 6 mm3 (=5.3 cm3) and 12 g, respectively, it generates 1.04 mW power output (into 190 Ω load) when it is vibrated at 75 Hz with vibration amplitude of 220 μm.
Harne, Ryan L
2012-07-01
Conversion of ambient vibrational energy into electric power has been the impetus of much modern research. The traditional analysis has focused on absolute electrical power output from the harvesting devices and efficiency defined as the convertibility of an infinite resource of vibration excitation into power. This perspective has limited extensibility when applying resonant harvesters to host resonant structures when the inertial influence of the harvester is more significant. Instead, this work pursues a fundamental understanding of the coupled dynamics of a main mass-spring-damper system to which an electromagnetic or piezoelectric mass-spring-damper is attached. The governing equations are derived, a metric of efficiency is presented, and analysis is undertaken. It is found that electromagnetic energy harvesting efficiency and maximum power output is limited by the strength of the coupling such that no split system resonances are induced for a given mass ratio. For piezoelectric harvesters, only the coupling strength and certain design requirements dictate maximum power and efficiency achievable. Since the harvesting circuitry must "follow" the split resonances as the piezoelectric harvesters become more massive, the optimum design of piezoelectric harvesters appears to be more involved than for electromagnetic devices.
Optimization design of high power ultrasonic circular ring radiator in coupled vibration.
Xu, Long; Lin, Shuyu; Hu, Wenxu
2011-10-01
This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction.
Nonlinear mode coupling and vibrational energy transfer in Yukawa clusters
NASA Astrophysics Data System (ADS)
Qiao, Ke; Kong, Jie; Matthews, Lorin; Hyde, Truell
2015-11-01
Nonlinear mode coupling and the subsequent vibrational energy transfer that results is an important topic in chemical physics research, ranging from small molecules consisting of several atoms to macromolecules such as those found in proteins and DNA. Nonlinear mode coupling is recognized as the mechanism leading to ergodicity, which is a foundational tenet of statistical mechanics. Over the past two decades, Yukawa systems of particles such as those found in complex plasma, have been shown to be an effective model across a large number of physical systems. In this research, nonlinear mode coupling in Yukawa clusters consisting of 3-10 particles is examined via numerical simulation of the vibrational energy transfer between modes starting from an initial excited state. The relationship between the energy transfer process and the internal resonance between modes having a specified frequency ratio and the temporal evolution of the system to a state of equal energy across all modes, i.e., the state of ergodicity, will be discussed. Support from the NSF and the DOE (award numbers PHY-1262031 and PHY-1414523) is gratefully acknowledged.
NASA Astrophysics Data System (ADS)
Tsampas, P.; Roditis, G.; Papadimitriou, V.; Chatzakos, P.; Gan, Tat-Hean
2013-05-01
Increasing demand in mobile, autonomous devices has made energy harvesting a particular point of interest. Systems that can be powered up by a few hundreds of microwatts could feature their own energy extraction module. Energy can be harvested from the environment close to the device. Particularly, the ambient mechanical vibrations conversion via piezoelectric transducers is one of the most investigated fields for energy harvesting. A technique for optimized energy harvesting using piezoelectric actuators called "Synchronized Switching Harvesting" is explored. Comparing to a typical full bridge rectifier, the proposed harvesting technique can highly improve harvesting efficiency, even in a significantly extended frequency window around the piezoelectric actuator's resonance. In this paper, the concept of design, theoretical analysis, modeling, implementation and experimental results using CEDRAT's APA 400M-MD piezoelectric actuator are presented in detail. Moreover, we suggest design guidelines for optimum selection of the storage unit in direct relation to the characteristics of the random vibrations. From a practical aspect, the harvesting unit is based on dedicated electronics that continuously sense the charge level of the actuator's piezoelectric element. When the charge is sensed, to come to a maximum, it is directed to speedily flow into a storage unit. Special care is taken so that electronics operate at low voltages consuming a very small amount of the energy stored. The final prototype developed includes the harvesting circuit implemented with miniaturized, low cost and low consumption electronics and a storage unit consisting of a super capacitors array, forming a truly self-powered system drawing energy from ambient random vibrations of a wide range of characteristics.
NASA Astrophysics Data System (ADS)
Muthalif, Asan G. A.; Nordin, N. H. Diyana
2015-03-01
Harvesting energy from the surroundings has become a new trend in saving our environment. Among the established ones are solar panels, wind turbines and hydroelectric generators which have successfully grown in meeting the world's energy demand. However, for low powered electronic devices; especially when being placed in a remote area, micro scale energy harvesting is preferable. One of the popular methods is via vibration energy scavenging which converts mechanical energy (from vibration) to electrical energy by the effect of coupling between mechanical variables and electric or magnetic fields. As the voltage generated greatly depends on the geometry and size of the piezoelectric material, there is a need to define an optimum shape and configuration of the piezoelectric energy scavenger. In this research, mathematical derivations for unimorph piezoelectric energy harvester are presented. Simulation is done using MATLAB and COMSOL Multiphysics software to study the effect of varying the length and shape of the beam to the generated voltage. Experimental results comparing triangular and rectangular shaped piezoelectric beam are also presented.
Future Electric Ship and Power and Energy
2010-09-01
Navy Hybrid Electric Ship S&T Issues/Challenges Power Generation, Energy Storage , Power Distribution & Control, and Thermal Closing Thoughts...development of efficient power systems. 1. Power Generation: • Fuel Cells & Fuel Reforming • Advanced Generators 2. Energy Storage : • Batteries... Storage : •Advanced materials (high purity, high dielectric breakdown) •Increased energy density and high temperature operation Goal: Increased
Venezuelan energy resources and electric power system
Altimari, J.
1994-06-01
This article discusses the changing energy policy of Venezuela which is intended to make its electric power sector more competitive. The topics of the article include an overview of the power industry (both private and public utilities), energy sources, power system capacity, generation resources, power demand, load management, and energy conservation.
NASA Astrophysics Data System (ADS)
Harne, R. L.; Zhang, Chunlin; Li, Bing; Wang, K. W.
2016-07-01
Impulsive energies are abundant throughout the natural and built environments, for instance as stimulated by wind gusts, foot-steps, or vehicle-road interactions. In the interest of maximizing the sustainability of society's technological developments, one idea is to capture these high-amplitude and abrupt energies and convert them into usable electrical power such as for sensors which otherwise rely on less sustainable power supplies. In this spirit, the considerable sensitivity to impulse-type events previously uncovered for bistable oscillators has motivated recent experimental and numerical studies on the power generation performance of bistable vibration energy harvesters. To lead to an effective and efficient predictive tool and design guide, this research develops a new analytical approach to estimate the electroelastic response and power generation of a bistable energy harvester when excited by an impulse. Comparison with values determined by direct simulation of the governing equations shows that the analytically predicted net converted energies are very accurate for a wide range of impulse strengths. Extensive experimental investigations are undertaken to validate the analytical approach and it is seen that the predicted estimates of the impulsive energy conversion are in excellent agreement with the measurements, and the detailed structural dynamics are correctly reproduced. As a result, the analytical approach represents a significant leap forward in the understanding of how to effectively leverage bistable structures as energy harvesting devices and introduces new means to elucidate the transient and far-from-equilibrium dynamics of nonlinear systems more generally.
Vibration characterisation of cymbal transducers for power ultrasonic applications
NASA Astrophysics Data System (ADS)
Bejarano, F.; Feeney, A.; Lucas, M.
2012-08-01
A Class V cymbal flextensional transducer is composed of a piezoceramic disc or ring sandwiched between two cymbal-shaped shell end-caps. These end-caps act as mechanical transformers to convert high impedance, low radial displacement of the piezoceramic into low impedance, large axial motion of the end-cap. The cymbal transducer was developed in the early 1990's at Penn State University, and is an improvement of the moonie transducer which has been in use since the 1980's. Despite the fact that cymbal transducers have been used in many fields, both as sensors and actuators, due to its physical limitations its use has been mainly at low power intensities. It is only very recently that its suitability for high amplitude and high power applications has been studied, and consequently implementation in this area of research remains undeveloped. This paper employs experimental modal analysis (EMA), vibration response measurements and electrical impedance measurements to characterise two variations of the cymbal transducer design, both aimed at incorporation in ultrasonic cutting devices. The transducers are fabricated using the commercial Eccobond 45LV epoxy adhesive as the bonding agent. The first cymbal transducer is of the classic design where the piezoceramic disc is bonded directly to the end-caps. The second cymbal transducer includes a metal ring bonded to the outer edge of the piezoceramic disc. The reason for the inclusion of this metal ring is to improve the mechanical coupling with the end-caps. This would therefore make this design particularly suitable for power ultrasonic applications, reducing the possibility of debonding at the higher ultrasonic amplitudes. The experimental results demonstrate that the second cymbal design is a significant improvement on the more classic design, allowing the transducer to operate at higher voltages and higher amplitudes, exhibiting a linear response over a practical power ultrasonic device driving voltage range. The
From MEMS to macro-world: a micro-milling machined wideband vibration piezoelectric energy harvester
NASA Astrophysics Data System (ADS)
Iannacci, J.; Sordo, G.
2015-05-01
In this work, we discuss a novel mechanical resonator design for the realization of vibration Energy Harvester (EH) capable to deliver power levels in the mW range. The device overcomes the typical constraint of frequency narrowband operability of standard cantilevered EHs, by exploiting a circular-shaped resonator with an increased number of mechanical Degrees Of Freedom (DOFs), leading to several resonant modes in the range of vibrations of interest (i.e. multi-modal wideband EH). The device, named Four-Leaf Clover (FLC), is simulated in Ansys Worbench™, showing a significant number of resonant modes up to vibrations of around 2 kHz (modal eigenfrequencies analysis), and exhibiting levels of converted power up to a few mW at resonance (harmonic coupled-field analysis). The sole FLC mechanical structure is realized by micro-milling an Aluminum foil, while a cantilevered test structure also including PolyVinyliDene Fluoride (PVDF) film sheet is assembled in order to collect first experimental feedback on generated power levels. The first lab based tests show peak-to-peak voltages of several Volts when the cantilever is stimulated with a mechanical pulse. Further developments of this work will comprise the assembly of an FLC demonstrator with PVDF pads, and its experimental testing in order to validate the simulated results.
Optimal design of a vibration-based energy harvester using magnetostrictive material (MsM)
NASA Astrophysics Data System (ADS)
Hu, J.; Xu, F.; Huang, A. Q.; Yuan, F. G.
2011-01-01
In this study, an optimal vibration-based energy harvesting system using magnetostrictive material (MsM) was designed and tested to enable the powering of a wireless sensor. In particular, the conversion efficiency, converting from magnetic to electric energy, is approximately modeled from the magnetic field induced by the beam vibration. A number of factors that affect the output power such as the number of MsM layers, coil design and load matching are analyzed and explored in the design optimization. From the measurements, the open-circuit voltage can reach 1.5 V when the MsM cantilever beam operates at the second natural frequency 324 Hz. The AC output power is 970 µW, giving a power density of 279 µW cm - 3. The attempt to use electrical reactive components (either inductors or capacitors) to resonate the system at any frequency has also been analyzed and tested experimentally. The results showed that this approach is not feasible to optimize the power. Since the MsM device has low output voltage characteristics, a full-wave quadrupler has been designed to boost the rectified output voltage. To deliver the maximum output power to the load, a complex conjugate impedance matching between the load and the MsM device is implemented using a discontinuous conduction mode (DCM) buck-boost converter. The DC output power after the voltage quadrupler reaches 705 µW and the corresponding power density is 202 µW cm - 3. The output power delivered to a lithium rechargeable battery is around 630 µW, independent of the load resistance.
Kongsted, Jacob; Christiansen, Ove
2006-09-28
An automatic and general procedure for the calculation of geometrical derivatives of the energy and general property surfaces for molecular systems is developed and implemented. General expressions for an n-mode representation are derived, where the n-mode representation includes only the couplings between n or less degrees of freedom. The general expressions are specialized to derivative force fields and property surfaces, and a scheme for calculation of the numerical derivatives is implemented. The implementation is interfaced to electronic structure programs and may be used for both ground and excited electronic states. The implementation is done in the context of a vibrational structure program and can be used in combination with vibrational self-consistent field (VSCF), vibrational configuration interaction (VCI), vibrational Moller-Plesset, and vibrational coupled cluster calculations of anharmonic wave functions and calculation of vibrational averaged properties at the VSCF and VCI levels. Sample calculations are presented for fundamental vibrational energies and vibrationally averaged dipole moments and frequency dependent polarizabilities and hyperpolarizabilities of water and formaldehyde.
Characterization of a water pump for drum-type washing machine by vibration power approach
NASA Astrophysics Data System (ADS)
Heo, YongHwa; Kim, Kwang-joon
2015-03-01
Water pumps used in drum-type washing machines to save water are likely to make the washing process noisier than the one without those because the water pumps attached usually onto cabinet structure work as additional vibration and noise sources. In order to either counteract such vibration and noise problems by stiffness design of the cabinet structure or classify the water pumps from the view point of an acceptance test, characterization of the water pumps as excitation sources would be essential. In this paper, several methods to characterize a water pump as an excitation source are investigated. Measurements by traditional methods of blocked force and/or free velocity for a water pump of 35 W are presented. Two methods of vibration power suggested rather recently are reviewed. Then, another method of the vibration power is proposed. Estimations of the vibration power for the water pump operating on a beam structure are obtained and discussed comparatively.
Determination of stepsize parameters for intermolecular vibrational energy transfer
Tardy, D.C.
1992-03-01
Intermolecular energy transfer of highly excited polyatomic molecules plays an important role in many complex chemical systems: combustion, high temperature and atmospheric chemistry. By monitoring the relaxation of internal energy we have observed trends in the collisional efficiency ({beta}) for energy transfer as a function of the substrate's excitation energy and the complexities of substrate and deactivator. For a given substrate {beta} increases as the deactivator's mass increase to {approximately}30 amu and then exhibits a nearly constant value; this is due to a mass mismatch between the atoms of the colliders. In a homologous series of substrate molecules (C{sub 3}{minus}C{sub 8}) {beta} decreases as the number of atoms in the substrate increases; replacing F with H increases {beta}. All substrates, except for CF{sub 2}Cl{sub 2} and CF{sub 2}HCl below 10,000 cm{sup {minus}1}, exhibited that {beta} is independent of energy, i.e. <{Delta}E>{sub all} is linear with energy. The results are interpreted with a simple model which considers that {beta} is a function of the ocillators energy and its vibrational frequency. Limitations of current approximations used in high temperature unimolecular reactions were evaluated and better approximations were developed. The importance of energy transfer in product yields was observed for the photoactivation of perfluorocyclopropene and the photoproduction of difluoroethyne. 3 refs., 18 figs., 4 tabs.
NASA Astrophysics Data System (ADS)
Chiu, Yi; Hong, Hao-Chiao; Hsu, Wei-Hung
2016-12-01
A wideband vibrational electromagnetic energy harvester employing nonlinear spring effects is proposed and demonstrated. The harvesters were designed and fabricated by commercial rigid-flex printed circuit boards technology. Rigid FR-4 boards were used for mechanical support and coil winding, whereas flexible polyimide films were patterned for mechanical springs and mass platforms. Two sets of coils were patterned and fabricated in the harvester with an internal coil resistance of about 16 Ω each. Two rare-earth magnets were attached to the central platform as shuttle mass. The total dimension of the harvester was 20 × 20 × 4 mm3. In vibration tests, nonlinearity could be observed even at 0.1 grms vibration level due to the spring hardening effect. The frequency for peak induced voltage increased from 187 Hz at low vibration to 382 Hz at 5 grms vibration. The effective half-power bandwidth increased from 8 Hz at 0.1 grms to 32 Hz at 1 grms and 52 Hz at 5 grms due to the hysteresis in frequency response. For a matched load and 1 grms vibration at 250 Hz, the maximum output power was 160 nW, corresponding to a power density of 100 nW cm-3.
Vibrational energies for HFCO using a neural network sum of exponentials potential energy surface.
Pradhan, Ekadashi; Brown, Alex
2016-05-07
A six-dimensional potential energy surface (PES) for formyl fluoride (HFCO) is fit in a sum-of-products form using neural network exponential fitting functions. The ab initio data upon which the fit is based were computed at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12]/cc-pVTZ-F12 level of theory. The PES fit is accurate (RMSE = 10 cm(-1)) up to 10 000 cm(-1) above the zero point energy and covers most of the experimentally measured IR data. The PES is validated by computing vibrational energies for both HFCO and deuterated formyl fluoride (DFCO) using block improved relaxation with the multi-configuration time dependent Hartree approach. The frequencies of the fundamental modes, and all other vibrational states up to 5000 cm(-1) above the zero-point energy, are more accurate than those obtained from the previous MP2-based PES. The vibrational frequencies obtained on the PES are compared to anharmonic frequencies at the MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels of theory obtained using second-order vibrational perturbation theory. The new PES will be useful for quantum dynamics simulations for both HFCO and DFCO, e.g., studies of intramolecular vibrational redistribution leading to unimolecular dissociation and its laser control.
Energy Balance for Random Vibrations of Piecewise-Conservative Systems
NASA Astrophysics Data System (ADS)
IOURTCHENKO, D. V.; DIMENTBERG, M. F.
2001-12-01
Vibrations of systems with instantaneous or stepwise energy losses, e.g., due to impacts with imperfect rebounds, dry friction forces(s) (in which case the losses may be treated as instantaneous ones by appropriate introduction of the response energy) and/or active feedback “bang-bang” control of the systems' response are considered. Response of such (non-linear) systems to a white-noise random excitation is considered for the case where there are no other response energy losses. Thus, a simple linear energy growth with time between “jumps” is observed. Explicit expressions for the expected response energy are derived by direct application of the stochastic differential equations calculus, which contains the expected time interval between two consecutive jumps. The latter may be predicted as a solution to the relevant first-passage problem. Perturbational analysis of the relevant PDE for this problem for a certain vibroimpact system demonstrated the possibility for using the solution to the corresponding free vibration problem as a zero order approximation. The method is applied to an s.d.o.f. system with a feedback inertia control, designed according to a certain previously introduced “generalized reversed swings law”. Extensive Monte-Carlo simulation results are presented for this system as well as for several previously analyzed ones: system with impacts; system with dry friction; system with stiffness control; pendulum with controlled length. The results are compared with those due to the asymptotic stochastic averaging approach. Both methods are shown to provide adequate accuracy far beyond the expected applicability range of the asymptotic approach (which requires both excitation intensity and losses to be small), with direct energy balance being generally superior.
The influence of mass configurations on velocity amplified vibrational energy harvesters
NASA Astrophysics Data System (ADS)
O'Donoghue, D.; Frizzell, R.; Kelly, G.; Nolan, K.; Punch, J.
2016-05-01
Vibrational energy harvesters scavenge ambient vibrational energy, offering an alternative to batteries for the autonomous operation of low power electronics. Velocity amplified electromagnetic generators (VAEGs) utilize the velocity amplification effect to increase power output and operational bandwidth, compared to linear resonators. A detailed experimental analysis of the influence of mass ratio and number of degrees-of-freedom (dofs) on the dynamic behaviour and power output of a macro-scale VAEG is presented. Various mass configurations are tested under drop-test and sinusoidal forced excitation, and the system performances are compared. For the drop-test, increasing mass ratio and number of dofs increases velocity amplification. Under forced excitation, the impacts between the masses are more complex, inducing greater energy losses. This results in the 2-dof systems achieving the highest velocities and, hence, highest output voltages. With fixed transducer size, higher mass ratios achieve higher voltage output due to the superior velocity amplification. Changing the magnet size to a fixed percentage of the final mass showed the increase in velocity of the systems with higher mass ratios is not significant enough to overcome the reduction in transducer size. Consequently, the 3:1 mass ratio systems achieved the highest output voltage. These findings are significant for the design of future reduced-scale VAEGs.
NASA Astrophysics Data System (ADS)
Oxaal, J.; Hella, M.; Borca-Tasciuc, D.-A.
2016-12-01
This paper reports on electrostatic MEMS vibration energy harvesters with gap-closing interdigitated electrodes, designed for and tested on HVAC air ducts. The harvesters were fabricated on SOI wafers with 200 µm device layer using a custom microfabrication process. Designs with aspects ratio (electrodes’ gap versus depth) of 10 and 20 were implemented, while the overall footprint was approximately 1 cm × 1 cm in both cases. In order to enhance the power output, a dual-level physical stopper system was designed to control the minimum gap between the electrodes, which is a key parameter in the conversion process. The dual-level stopper utilizes cantilever beams to absorb a portion of the impact energy as the electrodes approach the impact point, and a film of parylene with nanometer thickness deposited on the electrode sidewalls. The parylene layer defines the absolute minimum gap and provides electrical insulation. The fabricated devices were first tested on a vibration shaker to characterize the resonant behavior. Devices with aspect ratio 10 were found to exhibit frequency up-conversion, which enhances the amount of converted power. Devices with both aspect ratios were found to exhibits spring hardening due to impact with the stoppers and spring softening behavior at increasing voltage bias. The highest power measured on shaker table for sinusoidal vibrations was 3.13 µW (includes enhancement due to frequency up-conversion driven by impact) for aspect ratio 10, and 0.166 µW for aspect ratio 20. The corresponding dimensional figure-of-merit, defined as the power output normalized to vibration acceleration and frequency, squared voltage and device mass, was in the range of 10 · 10-8 m V-2 for both devices, about an order of magnitude higher than state-of-the-art. Testing was carried out on HVAC air duct vibrating with an RMS acceleration of 155 mg RMS, a primary frequency of 60 Hz and a PSD of 7.15 · 10-2 g2 Hz-1. The peak power measured was
Energy harvesting for self-powered aerostructure actuation
NASA Astrophysics Data System (ADS)
Bryant, Matthew; Pizzonia, Matthew; Mehallow, Michael; Garcia, Ephrahim
2014-04-01
This paper proposes and experimentally investigates applying piezoelectric energy harvesting devices driven by flow induced vibrations to create self-powered actuation of aerostructure surfaces such as tabs, flaps, spoilers, or morphing devices. Recently, we have investigated flow-induced vibrations and limit cycle oscillations due to aeroelastic flutter phenomena in piezoelectric structures as a mechanism to harvest energy from an ambient fluid flow. We will describe how our experimental investigations in a wind tunnel have demonstrated that this harvested energy can be stored and used on-demand to actuate a control surface such as a trailing edge flap in the airflow. This actuated control surface could take the form of a separate and discrete actuated flap, or could constitute rotating or deflecting the oscillating energy harvester itself to produce a non-zero mean angle of attack. Such a rotation of the energy harvester and the associated change in aerodynamic force is shown to influence the operating wind speed range of the device, its limit cycle oscillation (LCO) amplitude, and its harvested power output; hence creating a coupling between the device's performance as an energy harvester and as a control surface. Finally, the induced changes in the lift, pitching moment, and drag acting on a wing model are quantified and compared for a control surface equipped with an oscillating energy harvester and a traditional, static control surface of the same geometry. The results show that when operated in small amplitude LCO the energy harvester adds negligible aerodynamic drag.
NASA Astrophysics Data System (ADS)
Takeya, Kouichi; Sasaki, Eiichi; Kobayashi, Yusuke
2016-01-01
A bridge vibration energy harvester has been proposed in this paper using a tuned dual-mass damper system, named hereafter Tuned Mass Generator (TMG). A linear electromagnetic transducer has been applied to harvest and make use of the unused reserve of energy the aforementioned damper system absorbs. The benefits of using dual-mass systems over single-mass systems for power generation have been clarified according to the theory of vibrations. TMG parameters have been determined considering multi-domain parameters, and TMG has been tuned using a newly proposed parameter design method. Theoretical analysis results have shown that for effective energy harvesting, it is essential that TMG has robustness against uncertainties in bridge vibrations and tuning errors, and the proposed parameter design method for TMG has demonstrated this feature.
NASA Astrophysics Data System (ADS)
Asanuma, H.; Hara, M.; Oguchi, H.; Kuwano, H.
2016-07-01
Previously, we succeeded in developing a new electret [termed a ferroelectric dipole electret (FDE)] having an extremely high electric field using a polarized ferroelectric material. However, the pull-in, in which an oscillator sticks to the FDE under its strong electrostatic force, poses a problem for practical vibration energy harvesters. In this study, we propose use of nonlinear restoring force of a spring with a stopper in order to prevent pull-in for FDE-based vibration energy harvesters. The spring with a stopper was designed using a finite element method (FEM) analysis such that the restoring force of the spring will exceed the electrostatic force of the FDE. The proposed harvester combines the FDE and the spring successfully, and generated electricity without the pull-in. It also showed the highest figure of merit of output power and wide frequency band when compared with other available electret-based vibration energy harvesters.
NASA Astrophysics Data System (ADS)
Schwarzer, D.; Kutne, P.; Schröder, C.; Troe, J.
2004-07-01
Intramolecular vibrational energy flow in excited bridged azulene-anthracene compounds is investigated by time-resolved pump-probe laser spectroscopy. The bridges consist of molecular chains and are of the type (CH2)m with m up to 6 as well as (CH2OCH2)n (n=1,2) and CH2SCH2. After light absorption into the azulene S1 band and subsequent fast internal conversion, excited molecules are formed where the vibrational energy is localized at the azulene side. The vibrational energy transfer through the molecular bridge to the anthracene side and, finally, to the surrounding medium is followed by probing the red edge of the azulene S3 absorption band at 300 nm and/or the anthracene S1 absorption band at 400 nm. In order to separate the time scales for intramolecular and intermolecular energy transfer, most of the experiments were performed in supercritical xenon where vibrational energy transfer to the bath is comparably slow. The intramolecular equilibration proceeds in two steps. About 15%-20% of the excitation energy leaves the azulene side within a short period of 300 fs. This component accompanies the intramolecular vibrational energy redistribution (IVR) within the azulene chromophore and it is caused by dephasing of normal modes contributing to the initial local excitation of the azulene side and extending over large parts of the molecule. Later, IVR in the whole molecule takes place transferring vibrational energy from the azulene through the bridge to the anthracene side and thereby leading to microcanonical equilibrium. The corresponding time constants τIVR for short bridges increase with the chain length. For longer bridges consisting of more than three elements, however, τIVR is constant at around 4-5 ps. Comparison with molecular dynamics simulations suggests that the coupling of these chains to the two chromophores limits the rate of intramolecular vibrational energy transfer. Inside the bridges the energy transport is essentially ballistic and, therefore
Hu, Youfan; Yang, Jin; Jing, Qingshen; Niu, Simiao; Wu, Wenzhuo; Wang, Zhong Lin
2013-11-26
An unstable mechanical structure that can self-balance when perturbed is a superior choice for vibration energy harvesting and vibration detection. In this work, a suspended 3D spiral structure is integrated with a triboelectric nanogenerator (TENG) for energy harvesting and sensor applications. The newly designed vertical contact-separation mode TENG has a wide working bandwidth of 30 Hz in low-frequency range with a maximum output power density of 2.76 W/m(2) on a load of 6 MΩ. The position of an in-plane vibration source was identified by placing TENGs at multiple positions as multichannel, self-powered active sensors, and the location of the vibration source was determined with an error less than 6%. The magnitude of the vibration is also measured by the output voltage and current signal of the TENG. By integrating the TENG inside a buoy ball, wave energy harvesting at water surface has been demonstrated and used for lighting illumination light, which shows great potential applications in marine science and environmental/infrastructure monitoring.
Mode-specific energy absorption by solvent molecules during CO2 vibrational cooling.
Kandratsenka, Alexander; Schroeder, Jörg; Schwarzer, Dirk; Vikhrenko, Vyacheslav S
2007-04-14
Non-equilibrium molecular dynamics (NEMD) simulations of energy transfer from vibrationally excited CO(2) to CCl(4) and CH(2)Cl(2) solvent molecules are performed to identify the efficiency of different energy pathways into the solvent bath. Studying in detail the work performed by the vibrationally excited solute on the different solvent degrees of freedom, it is shown that vibration-to-vibration (V-V) processes are strongly dominant and controlled by those accepting modes which are close in frequency to the CO(2) bend and symmetric stretch vibration.
Accurate studies of dissociation energies and vibrational energies on alkali metals
NASA Astrophysics Data System (ADS)
Liu, Xiu-Ying; Sun, Wei-Guo; Fan, Qun-Chao
2008-06-01
This paper studies full vibrational spectra {Ev} and molecular dissociation energies De by using conventional least-squares (LS) fitting and an algebraic method (AM) proposed recently for 10 diatomic electronic states of 7Li2, Na2, NaK and NaLi molecules based on some known experimental vibrational energies in a subset [Evexpt] respectively. Studies show that: (1) although both the full AM spectrum {EvAM} and the LS spectrum {EvLS} can reproduce the known experimental energies in [Evexpt], the {EvAM} is superior to the {EvLS} in that the high-lying AM vibrational energies which may not be available experimentally have better or much better accuracy than those LS counterparts in {EvLS}, and so is the AM dissociation energy DeAM; (2) the main source of the errors in the data obtained by using the LS fitting is that the fitting which is just a pure mathematical process does not use any physical criteria that must be satisfied by the full vibrational spectrum, while the AM method does. This study suggests that when fitting or solving a physical equation using a set of source data, it is important not only to apply a proper mathematical tool, but also to use correct physical criteria which measure the physical properties of the data, kick out those data having bigger errors, and impose conditional convergence on the numerical process.
Remote Electromagnetic Vibration of Steerable Needles for Imaging in Power Doppler Ultrasound
Cabreros, Sarah S.; Jimenez, Nina M.; Greer, Joseph D.; Adebar, Troy K.; Okamura, Allison M.
2015-01-01
Robotic needle steering systems for minimally invasive medical procedures require complementary medical imaging systems to track the needles in real time. Ultrasound is a promising imaging modality because it offers relatively low-cost, real-time imaging of the needle. Previous methods applied vibration to the base of the needle using a voice coil actuator, in order to make the needle visible in power Doppler ultrasound. We propose a new method for needle tip vibration, using electromagnetic actuation of small permanent magnets placed inside the needle to improve needle tip visibility in power Doppler imaging. Robotic needle insertion experiments using artificial tissue and ex vivo porcine liver showed that the electromagnetic tip vibration method can generate a stronger Doppler response compared to the previous base vibration method, resulting in better imaging at greater needle depth in tissue. It also eliminates previous issues with vibration damping along the shaft of the needle. PMID:26413379
Remote Electromagnetic Vibration of Steerable Needles for Imaging in Power Doppler Ultrasound.
Cabreros, Sarah S; Jimenez, Nina M; Greer, Joseph D; Adebar, Troy K; Okamura, Allison M
2015-05-01
Robotic needle steering systems for minimally invasive medical procedures require complementary medical imaging systems to track the needles in real time. Ultrasound is a promising imaging modality because it offers relatively low-cost, real-time imaging of the needle. Previous methods applied vibration to the base of the needle using a voice coil actuator, in order to make the needle visible in power Doppler ultrasound. We propose a new method for needle tip vibration, using electromagnetic actuation of small permanent magnets placed inside the needle to improve needle tip visibility in power Doppler imaging. Robotic needle insertion experiments using artificial tissue and ex vivo porcine liver showed that the electromagnetic tip vibration method can generate a stronger Doppler response compared to the previous base vibration method, resulting in better imaging at greater needle depth in tissue. It also eliminates previous issues with vibration damping along the shaft of the needle.
NASA Astrophysics Data System (ADS)
Basset, P.; Galayko, D.; Cottone, F.; Guillemet, R.; Blokhina, E.; Marty, F.; Bourouina, T.
2014-03-01
This paper presents an advanced study including the design, characterization and theoretical analysis of a capacitive vibration energy harvester. Although based on a resonant electromechanical device, it is intended for operation in a wide frequency band due to the combination of stop-end effects and a strong biasing electrical field. The electrostatic transducer has an interdigited comb geometry with in-plane motion, and is obtained through a simple batch process using two masks. A continuous conditioning circuit is used for the characterization of the transducer. A nonlinear model of the coupled system ‘transduce-conditioning circuit’ is presented and analyzed employing two different semi-analytical techniques together with precise numerical modelling. Experimental results are in good agreement with results obtained from numerical modelling. With the 1 g amplitude of harmonic external acceleration at atmospheric pressure, the system transducer-conditioning circuit has a half-power bandwidth of more than 30% and converts more than 2 µW of the power of input mechanical vibrations over the range of 140 and 160 Hz. The harvester has also been characterized under stochastic noise-like input vibrations.
Sassani, Farrokh
2014-01-01
The simulation results for electromagnetic energy harvesters (EMEHs) under broad band stationary Gaussian random excitations indicate the importance of both a high transformation factor and a high mechanical quality factor to achieve favourable mean power, mean square load voltage, and output spectral density. The optimum load is different for random vibrations and for sinusoidal vibration. Reducing the total damping ratio under band-limited random excitation yields a higher mean square load voltage. Reduced bandwidth resulting from decreased mechanical damping can be compensated by increasing the electrical damping (transformation factor) leading to a higher mean square load voltage and power. Nonlinear EMEHs with a Duffing spring and with linear plus cubic damping are modeled using the method of statistical linearization. These nonlinear EMEHs exhibit approximately linear behaviour under low levels of broadband stationary Gaussian random vibration; however, at higher levels of such excitation the central (resonant) frequency of the spectral density of the output voltage shifts due to the increased nonlinear stiffness and the bandwidth broadens slightly. Nonlinear EMEHs exhibit lower maximum output voltage and central frequency of the spectral density with nonlinear damping compared to linear damping. Stronger nonlinear damping yields broader bandwidths at stable resonant frequency. PMID:24605063
Khan, Farid; Stoeber, Boris; Sassani, Farrokh
2014-01-01
The simulation results for electromagnetic energy harvesters (EMEHs) under broad band stationary Gaussian random excitations indicate the importance of both a high transformation factor and a high mechanical quality factor to achieve favourable mean power, mean square load voltage, and output spectral density. The optimum load is different for random vibrations and for sinusoidal vibration. Reducing the total damping ratio under band-limited random excitation yields a higher mean square load voltage. Reduced bandwidth resulting from decreased mechanical damping can be compensated by increasing the electrical damping (transformation factor) leading to a higher mean square load voltage and power. Nonlinear EMEHs with a Duffing spring and with linear plus cubic damping are modeled using the method of statistical linearization. These nonlinear EMEHs exhibit approximately linear behaviour under low levels of broadband stationary Gaussian random vibration; however, at higher levels of such excitation the central (resonant) frequency of the spectral density of the output voltage shifts due to the increased nonlinear stiffness and the bandwidth broadens slightly. Nonlinear EMEHs exhibit lower maximum output voltage and central frequency of the spectral density with nonlinear damping compared to linear damping. Stronger nonlinear damping yields broader bandwidths at stable resonant frequency.
Exploring Energy, Power, and Transportation Technology.
ERIC Educational Resources Information Center
Bowers, Donovan; Kellum, Mary
These teacher's materials for a seven-unit course were developed to help students develop technological literacy, career exploration, and problem-solving skills relative to the communication industries. The seven units include an overview of energy and power, principles of energy and power, power production and conversion, power transmission and…
NASA Astrophysics Data System (ADS)
Yuan, G.; Wang, D. H.
2017-03-01
Multi-directional and multi-degree-of-freedom (multi-DOF) vibration energy harvesting are attracting more and more research interest in recent years. In this paper, the principle of a piezoelectric six-DOF vibration energy harvester based on parallel mechanism is proposed to convert the energy of the six-DOF vibration to single-DOF vibrations of the limbs on the energy harvester and output voltages. The dynamic model of the piezoelectric six-DOF vibration energy harvester is established to estimate the vibrations of the limbs. On this basis, a Stewart-type piezoelectric six-DOF vibration energy harvester is developed and explored. In order to validate the established dynamic model and the analysis results, the simulation model of the Stewart-type piezoelectric six-DOF vibration energy harvester is built and tested with different vibration excitations by SimMechanics, and some preliminary experiments are carried out. The results show that the vibration of the limbs on the piezoelectric six-DOF vibration energy harvester can be estimated by the established dynamic model. The developed Stewart-type piezoelectric six-DOF vibration energy harvester can harvest the energy of multi-directional linear vibration and multi-axis rotating vibration with resonance frequencies of 17 Hz, 25 Hz, and 47 Hz. Moreover, the resonance frequencies of the developed piezoelectric six-DOF vibration energy harvester are not affected by the direction changing of the vibration excitation.
NASA Astrophysics Data System (ADS)
Hsu, Chang-Hung; Liu, Jui-Jung; Fu, Chao-Ming; Huang, Yi-Mei; Chang, Chia-Wen; Cheng, Shan-Jen
2015-05-01
This study investigated the effect of magnetostriction-induced core magnetomechanical vibrations and noise on the magnetic properties of power transformers. The magnetostriction of grain-oriented Si steels was found to be extremely sensitive to compressive stress applied along the rolling direction and to tensile stress applied along the transverse direction. The compressive stress increased the variation in the magnitude of magnetostriction, which is correlated with core vibration and noise. A 2D model of the power transformer was used to simulate the noise and vibration variables through a finite element analysis.
NASA Astrophysics Data System (ADS)
Pancharoen, K.; Zhu, D.; Beeby, S. P.
2016-11-01
This paper presents a magnetically levitated electromagnetic vibration energy harvester based on magnet arrays. It has a nonlinear response that extends the operating bandwidth and enhances the power output of the harvesting device. The harvester is designed to be embedded in a hip prosthesis and harvest energy from low frequency movements (< 5 Hz) associated with human motion. The design optimization is performed using Comsol simulation considering the constraints on size of the harvester and low operating frequency. The output voltage across the optimal load 3.5kΩ generated from hip movement is 0.137 Volts during walking and 0.38 Volts during running. The power output harvested from hip movement during walking and running is 5.35 μW and 41.36 μW respectively..
Electrostatic vibration energy harvester with 2.4-GHz Cockcroft-Walton rectenna start-up
NASA Astrophysics Data System (ADS)
Takhedmit, Hakim; Saddi, Zied; Karami, Armine; Basset, Philippe; Cirio, Laurent
2017-02-01
In this paper, we propose the design, fabrication and experiments of a macro-scale electrostatic vibration energy harvester (e-VEH), pre-charged wirelessly for the first time with a 2.4-GHz Cockcroft-Walton rectenna. The rectenna is designed and optimized to operate at low power densities and provide high voltage levels: 0.5 V at 0.76 μW/cm2 and 1 V at 1.53 μW/cm2. The e-VEH uses a Bennet doubler as a conditioning circuit. Experiments show a 23-V voltage across the transducer terminal, when the harvester is excited at 25 Hz by 1.5 g of external acceleration. An accumulated energy of 275 μJ and a maximum available power of 0.4 μW are achieved. xml:lang="fr"
NASA Astrophysics Data System (ADS)
Asanuma, H.; Okubo, H.; Komatsuzaki, T.; Iwata, Y.
2016-11-01
To downsize the clamp area and increase the output power of the harvester, we developed a miniature piezoelectric vibration energy harvester with combining a Z-shaped folded spring and a mechanically-switching SSHI (synchronized switch harvesting on inductor). The overall harvester size is 4×2×3 cm3. The FEM analysis revealed that the output power increases and the value of the 1st and 2nd resonance frequencies move closer as the angle of the Z-shaped spring decreases, therefore, the smaller angle would be more promising. The experimental results showed that the maximum output power of our harvester for the 1st (20.2 Hz) and 2nd (53.0 Hz) resonance frequencies at the applied acceleration of 4.9 m/s2 are 088 and 0.98 mW, respectively. The reason for a marked enhancement of the output power for the 2nd resonance frequency is attributed to the vertical movement of the 2nd vibrational mode which applies larger mechanical stress to the piezo ceramic and achieves better electrical contact between the tip of the Z-shaped spring and the spring plunger.
A modal approach to modeling spatially distributed vibration energy dissipation.
Segalman, Daniel Joseph
2010-08-01
The nonlinear behavior of mechanical joints is a confounding element in modeling the dynamic response of structures. Though there has been some progress in recent years in modeling individual joints, modeling the full structure with myriad frictional interfaces has remained an obstinate challenge. A strategy is suggested for structural dynamics modeling that can account for the combined effect of interface friction distributed spatially about the structure. This approach accommodates the following observations: (1) At small to modest amplitudes, the nonlinearity of jointed structures is manifest primarily in the energy dissipation - visible as vibration damping; (2) Correspondingly, measured vibration modes do not change significantly with amplitude; and (3) Significant coupling among the modes does not appear to result at modest amplitudes. The mathematical approach presented here postulates the preservation of linear modes and invests all the nonlinearity in the evolution of the modal coordinates. The constitutive form selected is one that works well in modeling spatially discrete joints. When compared against a mathematical truth model, the distributed dissipation approximation performs well.
Net energy analysis - powerful tool for selecting elective power options
Baron, S.
1995-12-01
A number of net energy analysis studies have been conducted in recent years for electric power production from coal, oil and uranium fuels; synthetic fuels from coal and oil shale; and heat and electric power from solar energy. This technique is an excellent indicator of investment costs, environmental impact and potential economic competitiveness of alternative electric power systems for energy planners from the Eastern European countries considering future options. Energy conservation is also important to energy planners and the net energy analysis technique is an excellent accounting system on the extent of energy resource conservation. The author proposes to discuss the technique and to present the results of his studies and others in the field. The information supplied to the attendees will serve as a powerful tool to the energy planners considering their electric power options in the future.
Auxetic piezoelectric energy harvesters for increased electric power output
NASA Astrophysics Data System (ADS)
Li, Qiang; Kuang, Yang; Zhu, Meiling
2017-01-01
This letter presents a piezoelectric bimorph with auxetic (negative Poisson's ratio) behaviors for increased power output in vibration energy harvesting. The piezoelectric bimorph comprises a 2D auxetic substrate sandwiched between two piezoelectric layers. The auxetic substrate is capable of introducing auxetic behaviors and thus increasing the transverse stress in the piezoelectric layers when the bimorph is subjected to a longitudinal stretching load. As a result, both 31- and 32-modes are simultaneously exploited to generate electric power, leading to an increased power output. The increasing power output principle was theoretically analyzed and verified by finite element (FE) modelling. The FE modelling results showed that the auxetic substrate can increase the transverse stress of a bimorph by 16.7 times. The average power generated by the auxetic bimorph is 2.76 times of that generated by a conventional bimorph.
Careers in Geothermal Energy: Power from below
ERIC Educational Resources Information Center
Liming, Drew
2013-01-01
In the search for new energy resources, scientists have discovered ways to use the Earth itself as a valuable source of power. Geothermal power plants use the Earth's natural underground heat to provide clean, renewable energy. The geothermal energy industry has expanded rapidly in recent years as interest in renewable energy has grown. In 2011,…
Rectifying the output of vibrational piezoelectric energy harvester using quantum dots.
Li, Lijie
2017-03-20
Piezoelectric energy harvester scavenges mechanical vibrations and generates electricity. Researchers have strived to optimize the electromechanical structures and to design necessary external power management circuits, aiming to deliver high power and rectified outputs ready for serving as batteries. Complex deformation of the mechanical structure results in charges with opposite polarities appearing on same surface, leading to current loss in the attached metal electrode. External power management circuits such as rectifiers comprise diodes that consume power and have undesirable forward bias. To address the above issues, we devise a novel integrated piezoelectric energy harvesting device that is structured by stacking a layer of quantum dots (QDs) and a layer of piezoelectric material. We find that the QD can rectify electrical charges generated from the piezoelectric material because of its adaptable conductance to the electrochemical potentials of both sides of the QDs layer, so that electrical current causing energy loss on the same surface of the piezoelectric material can be minimized. The QDs layer has the potential to replace external rectification circuits providing a much more compact and less power-consumption solution.
Rectifying the output of vibrational piezoelectric energy harvester using quantum dots
Li, Lijie
2017-01-01
Piezoelectric energy harvester scavenges mechanical vibrations and generates electricity. Researchers have strived to optimize the electromechanical structures and to design necessary external power management circuits, aiming to deliver high power and rectified outputs ready for serving as batteries. Complex deformation of the mechanical structure results in charges with opposite polarities appearing on same surface, leading to current loss in the attached metal electrode. External power management circuits such as rectifiers comprise diodes that consume power and have undesirable forward bias. To address the above issues, we devise a novel integrated piezoelectric energy harvesting device that is structured by stacking a layer of quantum dots (QDs) and a layer of piezoelectric material. We find that the QD can rectify electrical charges generated from the piezoelectric material because of its adaptable conductance to the electrochemical potentials of both sides of the QDs layer, so that electrical current causing energy loss on the same surface of the piezoelectric material can be minimized. The QDs layer has the potential to replace external rectification circuits providing a much more compact and less power-consumption solution. PMID:28317841
Rectifying the output of vibrational piezoelectric energy harvester using quantum dots
NASA Astrophysics Data System (ADS)
Li, Lijie
2017-03-01
Piezoelectric energy harvester scavenges mechanical vibrations and generates electricity. Researchers have strived to optimize the electromechanical structures and to design necessary external power management circuits, aiming to deliver high power and rectified outputs ready for serving as batteries. Complex deformation of the mechanical structure results in charges with opposite polarities appearing on same surface, leading to current loss in the attached metal electrode. External power management circuits such as rectifiers comprise diodes that consume power and have undesirable forward bias. To address the above issues, we devise a novel integrated piezoelectric energy harvesting device that is structured by stacking a layer of quantum dots (QDs) and a layer of piezoelectric material. We find that the QD can rectify electrical charges generated from the piezoelectric material because of its adaptable conductance to the electrochemical potentials of both sides of the QDs layer, so that electrical current causing energy loss on the same surface of the piezoelectric material can be minimized. The QDs layer has the potential to replace external rectification circuits providing a much more compact and less power-consumption solution.
A Smart Load Interface and Voltage Regulator for Electrostatic Vibration Energy Harvester
NASA Astrophysics Data System (ADS)
Bedier, Mohammed; Basset, Philippe; Galayko, Dimitri
2016-11-01
This paper presents a new implementation in ams 0.35μm HV technology of a complete energy management system for an electrostatic vibrational energy harvester (e-VEH). It is based on the Bennet's doubler architecture and includes a load voltage regulator (LVR) and a smart Load Interface (LI) that are self-controlled with internal voltages for maximum power point tracking (MMPT). The CMOS implementation makes use of an energy harvester that is capable of producing up to 1.8μW at harmonic excitation, given its internal voltage is kept within its optimum. An intermediate LI stage and its controller makes use of a high side switch with zero static power level shifter, and a low power hysteresis comparator. A full circuit level simulation with a VHDL-AMS model of the e-VEH presented was successfully achieved, indicating that the proposed load interface controller consumes less than 100nW average power. Moreover, a LVR regulates the buffer and discharge the harvested energy into a generic resistive load maintaining the voltage within a nominal value of 2 Volts.
NASA Astrophysics Data System (ADS)
Bab, Saeed; Khadem, S. E.; Shahgholi, Majid; Abbasi, Amirhassan
2017-02-01
The current paper investigates the effects of a number of smooth nonlinear energy sinks (NESs) located on the disk and bearings on the vibration attenuation of a rotor-blisk-journal bearing system under excitation of a mass eccentricity force. The blade and rotor are modeled using the Euler-Bernoulli beam theory. The nonlinear energy sinks on the bearing have a linear damping and an essentially nonlinear stiffness. The nonlinear energy sinks on the disk have a linear damping, linear stiffness, and an essentially nonlinear stiffness. It can be seen that the linear stiffness of the NESs on the disk is eliminated by the negative stiffness induced by the centrifugal force, and the collection of the NESs can be tuned to a required rotational speed of the rotor by varying the linear stiffness of the NESs. Furthermore, the remained stiffness of the NESs on the disk after elimination of their linear stiffness, would be essentially a nonlinear (nonlinearizable) one. Two nonlinear energy sinks in the vertical axes are positioned on the bearing housing and nnd NESs are located on the perimeter of the disk. The equations of motion are extracted using the extended Hamilton principle. The modal coordinates and complex transformations are employed to decrease the number of equations of motion. A genetic algorithm is used to optimize the parameters of the nonlinear energy sinks and its objective function is considered as minimizing the vibration of the rotating system within an operating speed range. In order to examine the periodic and non-periodic solutions of the system, time history, bifurcation diagram, Poincaré map, phase portrait, Lyapunov exponent, and power spectra analyses are performed. System shows periodic and quasi-periodic motions for different values of the system parameters. It is shown that the NESs on the disk and bearings have almost local effects on vibration reduction of rotating system. In addition, the optimum NESs remove the instability region from the
A reduced energy supply strategy in active vibration control
NASA Astrophysics Data System (ADS)
Ichchou, M. N.; Loukil, T.; Bareille, O.; Chamberland, G.; Qiu, J.
2011-12-01
In this paper, a control strategy is presented and numerically tested. This strategy aims to achieve the potential performance of fully active systems with a reduced energy supply. These energy needs are expected to be comparable to the power demands of semi-active systems, while system performance is intended to be comparable to that of a fully active configuration. The underlying strategy is called 'global semi-active control'. This control approach results from an energy investigation based on management of the optimal control process. Energy management encompasses storage and convenient restitution. The proposed strategy monitors a given active law without any external energy supply by considering purely dissipative and energy-demanding phases. Such a control law is offered here along with an analysis of its properties. A suboptimal form, well adapted for practical implementation steps, is also given. Moreover, a number of numerical experiments are proposed in order to validate test findings.
The molecular potential energy surface and vibrational energy levels of methyl fluoride. Part II.
Manson, Steven A; Law, Mark M; Atkinson, Ian A; Thomson, Grant A
2006-06-28
New analytical bending and stretching, ground electronic state, potential energy surfaces for CH(3)F are reported. The surfaces are expressed in bond-length, bond-angle internal coordinates. The four-dimensional stretching surface is an accurate, least squares fit to over 2000 symmetrically unique ab initio points calculated at the CCSD(T) level. Similarly, the five-dimensional bending surface is a fit to over 1200 symmetrically unique ab initio points. This is an important first stage towards a full nine-dimensional potential energy surface for the prototype CH(3)F molecule. Using these surfaces, highly excited stretching and (separately) bending vibrational energy levels of CH(3)F are calculated variationally using a finite basis representation method. The method uses the exact vibrational kinetic energy operator derived for XY(3)Z systems by Manson and Law (preceding paper, Part I, Phys. Chem. Chem. Phys., 2006, 8, DOI: 10.1039/b603106d). We use the full C(3v) symmetry and the computer codes are designed to use an arbitrary potential energy function. Ultimately, these results will be used to design a compact basis for fully coupled stretch-bend calculations of the vibrational energy levels of the CH(3)F system.
Orientation of bluff body for designing efficient energy harvesters from vortex-induced vibrations
Dai, H. L.; Abdelkefi, A.; Yang, Y.; Wang, L.
2016-02-01
The characteristics and performances of four distinct vortex-induced vibrations (VIVs) piezoelectric energy harvesters are experimentally investigated and compared. The difference between these VIV energy harvesters is the installation of the cylindrical bluff body at the tip of cantilever beam with different orientations (bottom, top, horizontal, and vertical). Experiments show that the synchronization regions of the bottom, top, and horizontal configurations are almost the same at low wind speeds (around 1.5 m/s). The vertical configuration has the highest wind speed for synchronization (around 3.5 m/s) with the largest harvested power, which is explained by its highest natural frequency and the smallest coupled damping. The results lead to the conclusion that to design efficient VIV energy harvesters, the bluff body should be aligned with the beam for low wind speeds (<2 m/s) and perpendicular to the beam at high wind speeds (>2 m/s)
Harvesting energy from the vibration of a passing train using a single-degree-of-freedom oscillator
NASA Astrophysics Data System (ADS)
Gatti, G.; Brennan, M. J.; Tehrani, M. G.; Thompson, D. J.
2016-01-01
With the advent of wireless sensors, there has been an increasing amount of research in the area of energy harvesting, particularly from vibration, to power these devices. An interesting application is the possibility of harvesting energy from the track-side vibration due to a passing train, as this energy could be used to power remote sensors mounted on the track for strutural health monitoring, for example. This paper describes a fundamental study to determine how much energy could be harvested from a passing train. Using a time history of vertical vibration measured on a sleeper, the optimum mechanical parameters of a linear energy harvesting device are determined. Numerical and analytical investigations are both carried out. It is found that the optimum amount of energy harvested per unit mass is proportional to the product of the square of the input acceleration amplitude and the square of the input duration. For the specific case studied, it was found that the maximum energy that could be harvested per unit mass of the oscillator is about 0.25 J/kg at a frequency of about 17 Hz. The damping ratio for the optimum harvester was found to be about 0.0045, and the corresponding amplitude of the relative displacement of the mass is approximately 5 mm.
Pradhan, Ekadashi; Carreón-Macedo, José-Luis; Cuervo, Javier E; Schröder, Markus; Brown, Alex
2013-08-15
The ground state potential energy and dipole moment surfaces for CS2 have been determined at the CASPT2/C:cc-pVTZ,S:aug-cc-pV(T+d)Z level of theory. The potential energy surface has been fit to a sum-of-products form using the neural network method with exponential neurons. A generic interface between neural network potential energy surface fitting and the Heidelberg MCTDH software package is demonstrated. The potential energy surface has also been fit using the potfit procedure in MCTDH. For fits to the low-energy regions of the potential, the neural network method requires fewer parameters than potfit to achieve high accuracy; global fits are comparable between the two methods. Using these potential energy surfaces, the vibrational energies have been computed for the four most abundant CS2 isotopomers. These results are compared to experimental and previous theoretical data. The current potential energy surfaces are shown to accurately reproduce the low-lying vibrational energies within a few wavenumbers. Hence, the potential energy and dipole moments surfaces will be useful for future study on the control of quantum dynamics in CS2.
Shock reliability analysis and improvement of MEMS electret-based vibration energy harvesters
NASA Astrophysics Data System (ADS)
Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.
2015-10-01
Vibration energy harvesters can serve as a replacement solution to batteries for powering tire pressure monitoring systems (TPMS). Autonomous wireless TPMS powered by microelectromechanical system (MEMS) electret-based vibration energy harvester have been demonstrated. The mechanical reliability of the MEMS harvester still has to be assessed in order to bring the harvester to the requirements of the consumer market. It should survive the mechanical shocks occurring in the tire environment. A testing procedure to quantify the shock resilience of harvesters is described in this article. Our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, the first important aspect is to understand the failure mechanism. Failure is found to occur in the form of fracture of the device’s springs. It results from impacts between the anchors of the springs when the harvester undergoes a shock. The shock resilience of the harvesters can be improved by redirecting these impacts to nonvital parts of the device. With this philosophy in mind, we design three types of shock absorbing structures and test their effect on the shock resilience of our MEMS harvesters. The solution leading to the best results consists of rigid silicon stoppers covered by a layer of Parylene. The shock resilience of the harvesters is brought above 2500 g. Results in the same range are also obtained with flexible silicon bumpers, which are simpler to manufacture.
Application of Energy Storage in Power Systems
NASA Astrophysics Data System (ADS)
Alqunun, Khalid M.
The purpose of this research is to determine the advantages of using energy storage systems. This study presents a model for energy storage in electric power systems. The model involves methods of reducing the operation cost of a power network and the calculation of capital cost of energy storage systems. Two test systems have been considered, the IEEE six-bus system and the IEEE 118-bus system, to analyze the impact of energy storage on power system economic operation. Properties of energy storage have been considered such as rated power investment cost and rated energy investment cost. Mixed integer programming has been used to formulate the model. A comparison between centralized energy storage system and distributed energy storage system have been proposed. The results show that distributed energy storage system has more impact on reducing total operation cost. Also, an analysis on optimal sizing of energy storage system with fixed investment cost is provided.
DSMC Modeling of Vibration-Vibration Energy Transfer Between Diatomic Molecules
Bondar, Ye. A.; Ivanov, M. S.
2008-12-31
Larsen-Borgnakke model, widely used in the DSMC method to simulate rotation-translation and vibration-translation exchanges in molecular collisions, is applied for the first time to resonant exchange between the vibrational modes of diatomic molecules (VV exchange). The validation of the model is performed through comparisons with experimental data on VV exchange in nitrogen.
Low-energy electron attachment and detachment in vibrationally excited oxygen
NASA Astrophysics Data System (ADS)
Aleksandrov, N. L.; Anokhin, E. M.
2009-11-01
Three-body electron attachment to O2 molecules and electron detachment from O_{2}^{-} ions have been theoretically studied in vibrationally excited oxygen and O2-containing mixtures. Assuming that electron attachment and detachment proceed via the formation of vibrationally excited temporary O_{2}^{-} ions, the rates of these processes were determined on the basis of the statistical approach for the vibrational transfer and relaxation in collisions between O_{2}^{-} ions and O2 molecules. The calculated attachment and detachment rate constants turned out to agree well with available measurements in unexcited oxygen. This method was extended to calculate attachment and detachment rates in vibrationally excited oxygen. It was shown that the effect of vibrational excitation on electron detachment is profound, whereas attachment of low-energy electrons to vibrationally excited O2 is inefficient. The calculated vibrational distribution of stable O_{2}^{-} ions turned out to be non-equilibrium in an excited gas and the effective vibrational temperature of the ions was much lower than the vibrational temperature of molecules. An analytical method was suggested to determine this distribution and the effective vibrational temperature. The calculated rate constants were used to simulate the formation and decay of an electron-beam-generated plasma in N2 : O2 mixtures at elevated vibrational temperatures. The calculations showed that vibrational excitation of molecules leads to orders of magnitude increase in the plasma density and in the plasma lifetime, in agreement with available observations.
Self-powered semi-passive vibration damping system based on self-sensing approach
NASA Astrophysics Data System (ADS)
Shen, Hui; Zhang, Fengsheng; Ji, Hongli; Qiu, Jinhao; Bian, Yixiang
2016-01-01
In recent years, semi-passive vibration damping using Synchronized Switching Damping on Inductor (SSDI) technique has been intensively investigated. In this paper, a self-powered semi-passive vibration damping system based on self sensing approach is proposed and investigated. With the self-sensing technique, the same piezoelectric element can be used as a sensor and an actuator. Compared with the other self-powered SSDI approaches, this technique can not only detect switching time without lag, but also reduce the number of piezoelectric elements. Furthermore, a low-power circuit for semi-passive piezoelectric vibration control based on self-sensing technique is designed. Experimental results demonstrate that the self-sensing SSDI system has good damping performance. The performance of the self-sensing SSDI system is also compared with the externally powered system.
Inversion vibration of PH3+(X~ 2A2'') studied by zero kinetic energy photoelectron spectroscopy
NASA Astrophysics Data System (ADS)
Yang, Jie; Li, Juan; Hao, Yusong; Zhou, Chang; Mo, Yuxiang
2006-08-01
We report the first rotationally resolved spectroscopic studies on PH3+(X˜A2″2) using zero kinetic energy photoelectron spectroscopy and coherent VUV radiation. The spectra about 8000cm-1 above the ground vibrational state of PH3+(X˜A2″2) have been recorded. We observed the vibrational energy level splittings of PH3+(X˜A2″2) due to the tunneling effect in the inversion (symmetric bending) vibration (ν2+). The energy splitting for the first inversion vibrational state (0+/0-) is 5.8cm-1. The inversion vibrational energy levels, rotational constants, and adiabatic ionization energies (IEs) for ν2+=0-16 have been determined. The bond angles between the neighboring P-H bonds and the P-H bond lengths are also obtained using the experimentally determined rotational constants. With the increasing of the inversion vibrational excitations (ν2+), the bond lengths (P-H) increase a little and the bond angles (H-P-H) decrease a lot. The inversion vibrational energy levels have also been calculated by using one dimensional potential model and the results are in good agreement with the experimental data for the first several vibrational levels. In addition to inversion vibration, we also observed firstly the other two vibrational modes: the symmetric P-H stretching vibration (ν1+) and the degenerate bending vibration (ν4+). The fundamental frequencies for ν1+ and ν4+ are 2461.6 (±2) and 1043.9 (±2)cm-1, respectively. The first IE for PH3 was determined as 79670.9 (±1)cm-1.
A Wind Energy Powered Wireless Temperature Sensor Node
Zhang, Chuang; He, Xue-Feng; Li, Si-Yu; Cheng, Yao-Qing; Rao, Yang
2015-01-01
A wireless temperature sensor node composed of a piezoelectric wind energy harvester, a temperature sensor, a microcontroller, a power management circuit and a wireless transmitting module was developed. The wind-induced vibration energy harvester with a cuboid chamber of 62 mm × 19.6 mm × 10 mm converts ambient wind energy into electrical energy to power the sensor node. A TMP102 temperature sensor and the MSP430 microcontroller are used to measure the temperature. The power management module consists of LTC3588-1 and LT3009 units. The measured temperature is transmitted by the nRF24l01 transceiver. Experimental results show that the critical wind speed of the harvester was about 5.4 m/s and the output power of the harvester was about 1.59 mW for the electrical load of 20 kΩ at wind speed of 11.2 m/s, which was sufficient to power the wireless sensor node to measure and transmit the temperature every 13 s. When the wind speed increased from 6 m/s to 11.5 m/s, the self-powered wireless sensor node worked normally. PMID:25734649
A wind energy powered wireless temperature sensor node.
Zhang, Chuang; He, Xue-Feng; Li, Si-Yu; Cheng, Yao-Qing; Rao, Yang
2015-02-27
A wireless temperature sensor node composed of a piezoelectric wind energy harvester, a temperature sensor, a microcontroller, a power management circuit and a wireless transmitting module was developed. The wind-induced vibration energy harvester with a cuboid chamber of 62 mm × 19.6 mm × 10 mm converts ambient wind energy into electrical energy to power the sensor node. A TMP102 temperature sensor and the MSP430 microcontroller are used to measure the temperature. The power management module consists of LTC3588-1 and LT3009 units. The measured temperature is transmitted by the nRF24l01 transceiver. Experimental results show that the critical wind speed of the harvester was about 5.4 m/s and the output power of the harvester was about 1.59 mW for the electrical load of 20 kΩ at wind speed of 11.2 m/s, which was sufficient to power the wireless sensor node to measure and transmit the temperature every 13 s. When the wind speed increased from 6 m/s to 11.5 m/s, the self-powered wireless sensor node worked normally.
A review of vibration problems in power station boiler feed pumps
NASA Technical Reports Server (NTRS)
France, David
1994-01-01
Boiler feed pump reliability and availability is recognized as important to the overall efficiency of power generation. Vibration monitoring is often used as a part of planned maintenance. This paper reviews a number of different types of boiler feed pump vibration problems describing some methods of solution in the process. It is hoped that this review may assist both designers and users faced with similar problems.
Vibration piezoelectric energy harvester with multi-beam
Cui, Yan Zhang, Qunying Yao, Minglei; Dong, Weijie; Gao, Shiqiao
2015-04-15
This work presents a novel vibration piezoelectric energy harvester, which is a micro piezoelectric cantilever with multi-beam. The characteristics of the PZT (Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3}) thin film were measured; XRD (X-ray diffraction) pattern and AFM (Atomic Force Microscope) image of the PZT thin film were measured, and show that the PZT (Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3}) thin film is highly (110) crystal oriented; the leakage current is maintained in nA magnitude, the residual polarisation Pr is 37.037 μC/cm{sup 2}, the coercive field voltage Ec is 27.083 kV/cm, and the piezoelectric constant d{sub 33} is 28 pC/N. In order to test the dynamic performance of the energy harvester, a new measuring system was set up. The maximum output voltage of the single beam of the multi-beam can achieve 80.78 mV under an acceleration of 1 g at 260 Hz of frequency; the maximum output voltage of the single beam of the multi-beam is almost 20 mV at 1400 Hz frequency. .
Hung, Chiao-Fang; Yeh, Po-Chen; Chung, Tien-Kan
2017-01-01
In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic–mechanical–piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x-axis and y-axis in-plane and z-axis magnetic fields into piezoelectric voltage outputs. Under the x-axis magnetic field (sine-wave, 100 Hz, 0.2–3.2 gauss) and the z-axis magnetic field (sine-wave, 142 Hz, 0.2–3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13–26.15 mV with 8.79 mV/gauss and 1.31–8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x-axis vibration (sine-wave, 100 Hz, 3.5 g) and z-axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on. PMID:28208693
Hung, Chiao-Fang; Yeh, Po-Chen; Chung, Tien-Kan
2017-02-08
In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic-mechanical-piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x-axis and y-axis in-plane and z-axis magnetic fields into piezoelectric voltage outputs. Under the x-axis magnetic field (sine-wave, 100 Hz, 0.2-3.2 gauss) and the z-axis magnetic field (sine-wave, 142 Hz, 0.2-3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13-26.15 mV with 8.79 mV/gauss and 1.31-8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x-axis vibration (sine-wave, 100 Hz, 3.5 g) and z-axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on.
Applications of energy harvesting for ultralow power technology
NASA Astrophysics Data System (ADS)
Pop-Vadean, A.; Pop, P. P.; Barz, C.; Chiver, O.
2015-06-01
Ultra-low-power (ULP) technology is enabling a wide range of new applications that harvest ambient energy in very small amounts and need little or no maintenance - self-sustaining devices that are capable of perpetual or nearly perpetual operation. These new systems, which are now appearing in industrial and consumer electronics, also promise great changes in medicine and health. Until recently, the idea of micro-scale energy harvesting, and collecting miniscule amounts of ambient energy to power electronic systems, was still limited to research proposals and laboratory experiments.Today an increasing number of systems are appearing that take advantage of light, vibrations and other forms of previously wasted environmental energy for applications where providing line power or maintaining batteries is inconvenient. In the industrial world, where sensors gather information from remote equipment and hazardous processes; in consumer electronics, where mobility and convenience are served; and in medical systems, with unique requirements for prosthetics and non-invasive monitoring, energy harvesting is rapidly expanding into new applications.This paper serves as a survey for applications of energy harvesting for ultra low power technology based on various technical papers available in the public domain.
Hiskes, J.R.; Karo, A.M.
1982-06-28
We consider the negative ion concentrations in hydrogen discharges caused by electron excitation and dissociative attachment processes. The principal formation and destruction processes are discussed for electron densities in the range 10/sup 8/ to 10/sup 13/ electrons cm/sup -3/. Expressions are developed for calculating the high energy portion of the electron energy distribution in the discharge; using these energy distributions the electron excitation rates are evaluated. At low densities, the vibrational distribution arises from singlet electronic excitations and triplet excitations through the /sup 3/..pi../sub u/ state, in equilibrium with wall de-excitation processes. At high densities singlet excitations predominate in equilibrium with atom-molecule de-excitation processes. Possibilities for negative ion generation in a two-chamber tandem system are discussed in which the vibrational excitation occurs in a high power, high electron temperature discharge, kT/sub e/ = 5 eV, and dissociative attachment occurs in a low temperature kT/sub e/ = 1 eV, plasma chamber.
Global Nonlinear Analysis of Piezoelectric Energy Harvesting from Ambient and Aeroelastic Vibrations
NASA Astrophysics Data System (ADS)
Abdelkefi, Abdessattar
Converting vibrations to a usable form of energy has been the topic of many recent investigations. The ultimate goal is to convert ambient or aeroelastic vibrations to operate low-power consumption devices, such as microelectromechanical systems, heath monitoring sensors, wireless sensors or replacing small batteries that have a finite life span or would require hard and expensive maintenance. The transduction mechanisms used for transforming vibrations to electric power include: electromagnetic, electrostatic, and piezoelectric mechanisms. Because it can be used to harvest energy over a wide range of frequencies and because of its ease of application, the piezoelectric option has attracted significant interest. In this work, we investigate the performance of different types of piezoelectric energy harvesters. The objective is to design and enhance the performance of these harvesters. To this end, distributed-parameter and phenomenological models of these harvesters are developed. Global analysis of these models is then performed using modern methods of nonlinear dynamics. In the first part of this Dissertation, global nonlinear distributed-parameter models for piezoelectric energy harvesters under direct and parametric excitations are developed. The method of multiple scales is then used to derive nonlinear forms of the governing equations and associated boundary conditions, which are used to evaluate their performance and determine the effects of the nonlinear piezoelectric coefficients on their behavior in terms of softening or hardening. In the second part, we assess the influence of the linear and nonlinear parameters on the dynamic behavior of a wing-based piezoaeroelastic energy harvester. The system is composed of a rigid airfoil that is constrained to pitch and plunge and supported by linear and nonlinear torsional and flexural springs with a piezoelectric coupling attached to the plunge degree of freedom. Linear analysis is performed to determine the
NASA Astrophysics Data System (ADS)
Seleznev, V. S.; Emanov, A. F.; Soloviev, V. M.; Glinsky, B. M.; Kashun, V. N.
The outcomes of work under the IRC project 1067 "Creation of calibration technology of seismic stations and seismic traces with use of high-power seismic vibrators", which was fulfilled by the Institute of Computational Mathematics and Mathematical Geo- physics SB RAS, Altai-Sayan Experimental Seismological Expedition SB RAS and Research Institute of Impulse Engineering of Russia Minatom, are given. The project is connected to problems of station calibration of an international system of monitor- ing of the Agreement of Mutual Ban of Nuclear Tests and provided for a research of wave fields of high-power vibrators and industrial explosions Within the realization of the project plan the researches on recording a high-power 100-ton fixed vibrator (located on a proving ground of Novosibirsk) on the areal aperture on distances to 400 km have been carried out. From recording results is shown that from a high-power vibrator of a vertical force reference waves from the interfaces in the Earth's crust (di- rect Pg-, Sg-, reflected PkP-, SkS-waves) and the Moho discontinuity (Pn-, Sn-, PmP-, SmS-waves) are stably recorded. The comparison of wave fields from a vibrator and industrial explosions has been made and the perspective scheme of station calibration (international and local network) with use of high-power fixed and movable vibrators has been developed. Basic outcomes of the project can be formulated as follows: 1) the perspective scheme of seismic station calibration of the international network on distances of 1500-2000 km using of vibrators of the increased power (more than 1000 tons of a force) has been grounded; 2) the calibration of seismic stations on distances of 500 - 1500 km has been developed and tested on practical examples on basis of combined method with use of data from vibrators of an average power (60-100-ton of a force) and information from seismological networks of earthquakes and indus- trial explosions; 3) from movable vibrators of low power (40
NASA Astrophysics Data System (ADS)
Hobeck, J. D.; Inman, D. J.
2014-11-01
Extensive research has been done on the topics of both turbulence-induced vibration and vibration based energy harvesting; however, little effort has been put into bringing these two topics together. Preliminary experimental studies have shown that piezoelectric structures excited by turbulent flow can produce significant amounts of useful power. This research could serve to benefit applications such as powering remote, self-sustained sensors in small rivers or air ventilation systems where turbulent fluid flow is a primary source of ambient energy. A novel solution for harvesting energy in these unpredictable fluid flow environments was explored by the authors in previous work, and a harvester prototype was developed. This prototype, called piezoelectric grass, has been the focus of many experimental studies. In this paper the authors present a theoretical analysis of the piezoelectric grass harvester modeled as a single unimorph cantilever beam exposed to turbulent cross-flow. This distributed parameter model was developed using a combination of both analytical and statistical techniques. The analytical portion uses a Rayleigh-Ritz approximation method to describe the beam dynamics, and utilizes piezoelectric constitutive relationships to define the electromechanical coupling effects. The statistical portion of the model defines the turbulence-induced forcing function distributed across the beam surface. The model presented in this paper was validated using results from several experimental case studies. Preliminary results show that the model agrees quite well with experimental data. A parameter optimization study was performed with the proposed model. This study demonstrated how a new harvester could be designed to achieve maximum power output in a given turbulent fluid flow environment.
Ab initio potential energy surface and vibration-rotation energy levels of beryllium monohydroxide.
Koput, Jacek
2017-01-05
The accurate potential energy surface of beryllium monohydroxide, BeOH, in its ground electronic state X 2A' has been determined from ab initio calculations using the coupled-cluster approach in conjunction with the correlation-consistent core-valence basis sets up to septuple-zeta quality. The higher-order electron correlation, scalar relativistic, and adiabatic effects were taken into account. The BeOH molecule was confirmed to be bent at equilibrium, with the BeOH angle of 141.2° and the barrier to linearity of 129 cm(-1) . The vibration-rotation energy levels of the BeOH and BeOD isotopologues were predicted using a variational approach and compared with recent experimental data. The results can be useful in a further analysis of high-resolution vibration-rotation spectra of these interesting species. © 2016 Wiley Periodicals, Inc.
Wang, Peihong; Du, Hejun
2015-07-01
Zinc oxide (ZnO) thin film piezoelectric microelectromechanical systems (MEMS) based vibration energy harvesters with two different designs are presented. These harvesters consist of a silicon cantilever, a silicon proof mass, and a ZnO piezoelectric layer. Design I has a large ZnO piezoelectric element and Design II has two smaller and equally sized ZnO piezoelectric elements; however, the total area of ZnO thin film in two designs is equal. The ZnO thin film is deposited by means of radio-frequency magnetron sputtering method and is characterized by means of XRD and SEM techniques. These ZnO energy harvesters are fabricated by using MEMS micromachining. The natural frequencies of the fabricated ZnO energy harvesters are simulated and tested. The test results show that these two energy harvesters with different designs have almost the same natural frequency. Then, the output performance of different ZnO energy harvesters is tested in detail. The effects of series connection and parallel connection of two ZnO elements on the load voltage and power are also analyzed. The experimental results show that the energy harvester with two ZnO piezoelectric elements in parallel connection in Design II has higher load voltage and higher load power than the fabricated energy harvesters with other designs. Its load voltage is 2.06 V under load resistance of 1 MΩ and its maximal load power is 1.25 μW under load resistance of 0.6 MΩ, when it is excited by an external vibration with frequency of 1300.1 Hz and acceleration of 10 m/s(2). By contrast, the load voltage of the energy harvester of Design I is 1.77 V under 1 MΩ resistance and its maximal load power is 0.98 μW under 0.38 MΩ load resistance when it is excited by the same vibration.
NASA Astrophysics Data System (ADS)
Karami, Armine; Basset, Philippe; Galayko, Dimitri
2015-12-01
This paper reports for the first time experiments using an electrostatic vibration energy harvester comprised of a low voltage electret-charged MEMS transducer joined to an unstable autosynchronous conditioning circuit with rectangular charge-voltage characteristic, also known as the Bennet's doubler conditioning circuit. The experimental results show that the electret voltage, even if of low value, can be used as the necessary pre-charge for these type of electrostatic vibration energy harvesters. Also, the use of such a conditioning circuit with a low-voltage electret capacitive MEMS tranducer instead of the previously-reported conditioning circuits with direct connection to load or through a rectifier, can be advantageous in terms of maximal harvested power for a low-voltage electret, showing up to 95% higher converted power.
Low-frequency and wideband vibration energy harvester with flexible frame and interdigital structure
Li, Pengwei Wang, Yanfen; Luo, Cuixian; Li, Gang; Hu, Jie; Zhang, Wendong; Liu, Ying; Liu, Wei
2015-04-15
As an alternative to traditional cantilever beam structures and their evolutions, a flexible beam based, interdigital structure, vibration energy harvester has been presented and investigated. The proposed interdigital-shaped oscillator consists of a rectangular flexible frame and series of cantilever beams interdigitally bonded to it. In order to achieve low frequency and wide-bandwidth harvesting, Young’s modulus of materials, frame size and the amount of the cantilevers have been studied systematically. The measured frequency responses of the designed device (PDMS frame, quintuple piezoelectric cantilever beams) show a 460% increase in bandwidth below 80Hz. When excited at an acceleration of 1.0 g, the energy harvester achieves to a maximum open-circuit voltage of 65V, and the maximum output power 4.5 mW.
Vibration energy harvester with low resonant frequency based on flexible coil and liquid spring
NASA Astrophysics Data System (ADS)
Wang, Y.; Zhang, Q.; Zhao, L.; Tang, Y.; Shkel, A.; Kim, E. S.
2016-11-01
This paper reports an electromagnetic vibration-energy harvester with low resonant frequency based on liquid spring composed of ferrofluid. Cylinder magnet array formed by four disc NdFeB magnets is suspended by ferrofluid in a laser-machined acrylic tube which is wrapped by flexible planar coil fabricated with microfabrication process. The magnet array and coil are aligned automatically by the ferrofluid. Restoring force when the magnet array is deviated from the balance position is proportional to the deviated distance, which makes the ferrofluid work as a liquid spring obeying Hook's law. Experimental results show that the electromagnetic energy harvester occupying 1.8 cc and weighing 5 g has a resonant frequency of 16 Hz and generates an induced electromotive force of Vrms = 2.58 mV (delivering 79 nW power into matched load of 21 Ω) from 3 g acceleration at 16 Hz.
Water Power for a Clean Energy Future
2013-04-12
This document describes some of the accomplishments of the Department of Energy Water Power Program, and how those accomplishments are supporting the advancement of renewable energy generated using hydropower technologies and marine and hydrokinetic technologies.
NASA Astrophysics Data System (ADS)
Pan, Xumin; Wang, Zhao; Cao, Zilan; Zhang, Shenqiu; He, Yahua; Zhang, Youdong; Chen, Kansong; Hu, Yongming; Gu, Haoshuang
2016-10-01
The development of self-powered vibration sensors using polymeric piezoelectric nanomaterials has attracted great attention owing to their outstanding flexibility and energy harvesting behaviours. In this study, ultra-long poly (vinylidene fluoride) (PVDF) nanofibres with optimised β-phase content were synthesised through electrospinning method with different DC voltages. The increase in the β-phase content of the PVDF nanofibres greatly enhanced their piezoelectric response with nearly tripled output voltage and current under the same strain condition. Moreover, the output voltage exhibited linear correlations with both the amplitude and frequency of the strain. Under a fixed frequency of 1.54 Hz, the output voltage exhibited a linear correlation to the strain amplitude with strain sensitivity up to 0.92 V rad-1 and 0.61 V mm-1. The frequency-dependent strain sensing behaviour also confirmed the necessity for frequency calibration to the measured results of vibration. Accordingly, the sensor can be used for self-powered monitoring of the vibration state of a metal foil and measuring the intrinsic resonance frequency of the objects without any powering source.
Harvesting broadband kinetic impact energy from mechanical triggering/vibration and water waves.
Wen, Xiaonan; Yang, Weiqing; Jing, Qingshen; Wang, Zhong Lin
2014-07-22
We invented a triboelectric nanogenerator (TENG) that is based on a wavy-structured Cu-Kapton-Cu film sandwiched between two flat nanostructured PTFE films for harvesting energy due to mechanical vibration/impacting/compressing using the triboelectrification effect. This structure design allows the TENG to be self-restorable after impact without the use of extra springs and converts direct impact into lateral sliding, which is proved to be a much more efficient friction mode for energy harvesting. The working mechanism has been elaborated using the capacitor model and finite-element simulation. Vibrational energy from 5 to 500 Hz has been harvested, and the generator's resonance frequency was determined to be ∼100 Hz at a broad full width at half-maximum of over 100 Hz, producing an open-circuit voltage of up to 72 V, a short-circuit current of up to 32 μA, and a peak power density of 0.4 W/m(2). Most importantly, the wavy structure of the TENG can be easily packaged for harvesting the impact energy from water waves, clearly establishing the principle for ocean wave energy harvesting. Considering the advantages of TENGs, such as cost-effectiveness, light weight, and easy scalability, this approach might open the possibility for obtaining green and sustainable energy from the ocean using nanostructured materials. Lastly, different ways of agitating water were studied to trigger the packaged TENG. By analyzing the output signals and their corresponding fast Fourier transform spectra, three ways of agitation were evidently distinguished from each other, demonstrating the potential of the TENG for hydrological analysis.
Reliability of vibration energy harvesters of metal-based PZT thin films
NASA Astrophysics Data System (ADS)
Tsujiura, Y.; Suwa, E.; Kurokawa, F.; Hida, H.; Kanno, I.
2014-11-01
This paper describes the reliability of piezoelectric vibration energy harvesters (PVEHs) of Pb(Zr,Ti)O3 (PZT) thin films on metal foil cantilevers. The PZT thin films were directly deposited onto the Pt-coated stainless-steel (SS430) cantilevers by rf-magnetron sputtering, and we observed their aging behavior of power generation characteristics under the resonance vibration condition for three days. During the aging measurement, there was neither fatigue failure nor degradation of dielectric properties in our PVEHs (length: 13 mm, width: 5.0 mm, thickness: 104 μm) even under a large excitation acceleration of 25 m/s2. However, we observed clear degradation of the generated electric voltage depending on excitation acceleration. The decay rate of the output voltage was 5% from the start of the measurement at 25 m/s2. The transverse piezoelectric coefficient (e31,f) also degraded with almost the same decay rate as that of the output voltage; this indicates that the degradation of output voltage was mainly caused by that of piezoelectric properties. From the decay curves, the output powers are estimated to degrade 7% at 15 m/s2 and 36% at 25 m/s2 if we continue to excite the PVEHs for 30 years.
High-efficiency MOSFET bridge rectifier for AlN MEMS cantilever vibration energy harvester
NASA Astrophysics Data System (ADS)
Takei, Ryohei; Okada, Hironao; Noda, Daiji; Ohta, Ryo; Takeshita, Toshihiro; Itoh, Toshihiro; Kobayashi, Takeishi
2017-04-01
We developed a high-efficiency MOSFET bridge rectifier for use in an aluminum nitride (AlN) piezoelectric MEMS cantilever vibration energy harvester (VEH). The bridge rectifier consists of four MOSFETs with a circuit configuration similar to that of a typical diode bridge rectifier. The output voltage of the full-wave rectification via the MOSFET bridge was simulated with an equivalent circuit model of the AlN VEH, which is extracted from an experimental result. The channel width of the MOSFET was designed to be adopted for use with a high-voltage and low-current AlN VEH. The designed rectifier was fabricated using the 0.18 µm high voltage technology of a commercially available CMOS foundry. The AlN VEH with our bridge rectifier generated a DC power of 0.514 µW at 2.49 V under an applied vibration with an acceleration amplitude of 0.5 m/s2 at a frequency of 46.6 Hz. The DC power is 1.4 times higher than that generated by the same AlN VEH with a MOSFET bridge consisting of commercially available discrete MOSFETs.
NASA Astrophysics Data System (ADS)
Shen, Wenai; Zhu, Songye; Zhu, Hongping
2016-06-01
Flexible bridge stay cables are often vulnerable to problematic vibrations under dynamic excitations. However, from an energy perspective, such excessive vibrations denote a green and sustainable energy source to some electronic devices (such as semi-active dampers or wireless sensors) installed on the same cables. This paper presents an experimental study on a novel dual-function system called electromagnetic damper cum energy harvester (EMDEH). The proposed EMDEH, consisting of an electromagnetic device connected to an energy-harvesting circuit (EHC), simultaneously harvests cable vibration energy and provides sufficient damping to the cables. A fixed-duty-cycle buck-boost converter is employed as the EHC, which emulates a resistive load and provides approximately optimal damping and optimal energy harvesting efficiency when operating in discontinuous conduction mode. A 5.85 m long scaled stay cable installed with a prototype EMDEH is tested in the laboratory under a series of harmonic and random excitations. The EMDEH can achieve a control performance comparable to passive viscous dampers. An average electrical power of 31.6 and 21.51 mW is harvested under harmonic and random vibrations, respectively, corresponding to the efficiency of 16.9% and 13.8%, respectively. Moreover, this experimental study proves that optimal damping and energy harvesting can be achieved simultaneously, which answers a pending question regarding such a dual-objective optimization problem. Self-powered semi-active control systems or wireless sensor networks may be developed for bridge stay cables in the future based on the proposed concept in this study.
Mechanism of emergence of intense vibrations of turbines on the Sayano-Shushensk hydro power plant
NASA Astrophysics Data System (ADS)
Kurzin, V. B.; Seleznev, V. S.
2010-07-01
It is demonstrated that the level of vibrations of turbines on the Sayano-Shushensk hydro power plant is enhanced by the capability of a compressible fluid to perform its own hydroacoustic oscillations (which can be unstable) in the turbine duct. Based on the previously obtained results of solving the problem of natural hydroacoustic oscillations in the turbine duct and some ideas about turbine interaction with an unsteady compressible fluid flow, results of full-scale studies of turbine vibrations and seismic monitoring of the dam of the Sayano-Shushensk hydro power plant before and during the accident are analyzed.
Solar energy thermally powered electrical generating system
NASA Technical Reports Server (NTRS)
Owens, William R. (Inventor)
1989-01-01
A thermally powered electrical generating system for use in a space vehicle is disclosed. The rate of storage in a thermal energy storage medium is controlled by varying the rate of generation and dissipation of electrical energy in a thermally powered electrical generating system which is powered from heat stored in the thermal energy storage medium without exceeding a maximum quantity of heat. A control system (10) varies the rate at which electrical energy is generated by the electrical generating system and the rate at which electrical energy is consumed by a variable parasitic electrical load to cause storage of an amount of thermal energy in the thermal energy storage system at the end of a period of insolation which is sufficient to satisfy the scheduled demand for electrical power to be generated during the next period of eclipse. The control system is based upon Kalman filter theory.
Liu, Jianbo; Uselman, Brady W; Boyle, Jason M; Anderson, Scott L
2006-10-07
A combined experimental and trajectory study of vibrationally state-selected NO2+ collisions with Ne, Ar, Kr, and Xe is presented. Ne, Ar, and Kr are similar in that only dissociation to the excited singlet oxygen channel is observed; however, the appearance energies vary by approximately 4 eV between the three rare gases, and the variation is nonmonotonic in rare gas mass. Xe behaves quite differently, allowing efficient access to the ground triplet state dissociation channel. For all four rare gases there are strong effects of NO2+ vibrational excitation that extend over the entire collision energy range, implying that vibration influences the efficiency of collision to internal energy conversion. Bending excitation is more efficient than stretching; however, bending angular momentum partially counters the enhancement. Direct dynamics trajectories for NO2+ + Kr reproduce both the collision energy and vibrational state effects observed experimentally and reveal that intracomplex charge transfer is critical for the efficient energy transfer needed to drive dissociation. The strong vibrational effects can be rationalized in terms of bending, and to a lesser extent, stretching distortion enhancing transition to the Kr+ -NO2 charge state.
ERIC Educational Resources Information Center
Holdren, John; Herrera, Philip
The demand of Americans for more and more power, particularly electric power, contrasted by the deep and growing concern for the environment and a desire by private citizens to participate in the public decisions that affect the environment is the dilemma explored in this book. Part One by John Holdren, offers a scientist's overview of the energy…
Pulsed Power Driven Fusion Energy
SLUTZ,STEPHEN A.
1999-11-22
Pulsed power is a robust and inexpensive technology for obtaining high powers. Considerable progress has been made on developing light ion beams as a means of transporting this power to inertial fusion capsules. However, further progress is hampered by the lack of an adequate ion source. Alternatively, z-pinches can efficiently convert pulsed power into thermal radiation, which can be used to drive an inertial fusion capsule. However, a z-pinch driven fusion explosion will destroy a portion of the transmission line that delivers the electrical power to the z-pinch. They investigate several options for providing standoff for z-pinch driven fusion. Recyclable Transmission Lines (RTLs) appear to be the most promising approach.
Field Telemetry of Blade-rotor Coupled Torsional Vibration at Matuura Power Station Number 1 Unit
NASA Technical Reports Server (NTRS)
Isii, Kuniyoshi; Murakami, Hideaki; Otawara, Yasuhiko; Okabe, Akira
1991-01-01
The quasi-modal reduction technique and finite element model (FEM) were used to construct an analytical model for the blade-rotor coupled torsional vibration of a steam turbine generator of the Matuura Power Station. A single rotor test was executed in order to evaluate umbrella vibration characteristics. Based on the single rotor test results and the quasi-modal procedure, the total rotor system was analyzed to predict coupled torsional frequencies. Finally, field measurement of the vibration of the last stage buckets was made, which confirmed that the double synchronous resonance was 124.2 Hz, meaning that the machine can be safely operated. The measured eigen values are very close to the predicted value. The single rotor test and this analytical procedure thus proved to be a valid technique to estimate coupled torsional vibration.
The influence of molecular rotation on vibration-translation energy transfer
NASA Technical Reports Server (NTRS)
Mckenzie, R. L.
1977-01-01
A three-dimensional vibration-rotation collision model is formulated within a semiclassical framework to study the effect of coupled rotational motion on the rate of vibrational energy transfer for collisions between anharmonic diatomic molecules and structureless atoms. Emphasis is on the net rates of vibrational energy transfer summed over all final rotational states rather than those for individual vibration-rotation transitions. The corresponding three-dimensional rate parameters are cast into forms that may be identified with equivalent parameters associated with the collinear approximation. Their comparisons allow the validity of a collinear model to be evaluated and some constraints on its application to be implied. The mechanisms of vibrational energy transfer including rotational transitions are shown to be separable into three classes which are identified and discussed
NASA Astrophysics Data System (ADS)
Brusa, E.; Zelenika, S.; Moro, L.; Benasciutti, D.
2009-05-01
One of the main requirements in wireless sensor operation is the availability of autonomous power sources sufficiently compact to be embedded in the same housing and, when the application involves living people, wearable. A possible technological solution satisfying these needs is energy harvesting from the environment. Vibration energy scavenging is one of the most studied approaches in this frame. In this work the conversion of kinetic into electric energy via piezoelectric coupling in resonant beams is studied. Various design approaches are analyzed and relevant parameters are identified. Numerical methods are applied to stress and strain analyses as well as to evaluate the voltage and charge generated by electromechanical coupling. The aim of the work is increasing the specific power generated per unit of scavenger volume by optimizing its shape. Besides the conventional rectangular geometry proposed in literature, two trapezoidal shapes, namely the direct and the reversed trapezoidal configuration, are analyzed. They are modeled to predict their dynamic behavior and energy conversion performance. Analytical and FEM models are compared and resulting figures of merit are drawn. Results of a preliminary experimental validation are also given. A systematic validation of characteristic specimens via an experimental campaign is ongoing.
Diameter-dependent dissipation of vibration energy of cantilevered multiwall carbon nanotubes.
Sawaya, Shintaro; Arie, Takayuki; Akita, Seiji
2011-04-22
This study investigated the mechanical properties of vibrating cantilevered multiwall carbon nanotubes in terms of energy loss in a vibrating nanotube. Young's moduli of the nanotubes show a clear dependence of the perfection of the sp(2) carbon network, as determined from Raman spectroscopy. The energy loss corresponding to the inverse of the quality factor increases with increasing tube diameter, although the nanotube maintains high mechanical strength around 0.5 TPa. This fact implies that the vibration energy is dissipated mainly not by defects, but by van der Waals interactions between walls.
NASA Astrophysics Data System (ADS)
Yan, Shuai; Sun, Weichao
2017-09-01
Active suspension systems have advantages on mitigating the effects of vehicle vibration caused by road roughness, which are one of the most important component parts in influencing the performances of vehicles. However, high amount of energy consumption restricts the application of active suspension systems. From the point of energy saving, this paper presents a self-powered criterion of the active suspension system to judge whether a motor-driven suspension can be self-powered or not, and then a motor parameter condition is developed as a reference to design a self-powered suspension. An energy regeneration implementation scheme is subsequently proposed to make the active suspension which has the potential to be self-powered achieve energy-saving target in the real application. In this implementation scheme, operating electric circuits are designed based on different working status of the actuator and power source and it is realizable to accumulate energy from road vibration and supply energy to the actuator by switching corresponding electric circuits. To apply the self-powered suspension criterion and energy regeneration implementation scheme, an active suspension system is designed with a constrained H∞ controller and calculation results indicate that it has the capability to be self-powered. Simulation results show that the performances of the self-powered active suspension are nearly the same as those of the active suspension with an external energy source and can achieve energy regeneration at the same time.
Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization
NASA Technical Reports Server (NTRS)
Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.
2014-01-01
This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise.
Compact inductive energy storage pulse power system.
K, Senthil; Mitra, S; Roy, Amitava; Sharma, Archana; Chakravarthy, D P
2012-05-01
An inductive energy storage pulse power system is being developed in BARC, India. Simple, compact, and robust opening switches, capable of generating hundreds of kV, are key elements in the development of inductive energy storage pulsed power sources. It employs an inductive energy storage and opening switch power conditioning techniques with high energy density capacitors as the primary energy store. The energy stored in the capacitor bank is transferred to an air cored storage inductor in 5.5 μs through wire fuses. By optimizing the exploding wire parameters, a compact, robust, high voltage pulse power system, capable of generating reproducibly 240 kV, is developed. This paper presents the full details of the system along with the experimental data.
Improved design of linear electromagnetic transducers for large-scale vibration energy harvesting
NASA Astrophysics Data System (ADS)
Tang, Xiudong; Zuo, Lei; Lin, Teng; Zhang, Peisheng
2011-03-01
This paper presents the design and optimization of tubular Linear Electromagnetic Transducers (LETs) with applications to large-scale vibration energy harvesting, such as from vehicle suspensions, tall buildings or long bridges. Four types of LETs are considered and compared, namely, single-layer configuration using axial magnets, double-layer configuration using axial magnets, single-layer configuration using both axial and radial magnets, double-layer configuration using both axial and radial magnets. In order to optimize the LETs, the parameters investigated in this paper include the thickness of the magnets in axial direction and the thickness of the coils in the radial direction. Finite element method is used to analyze the axisymmetric two-dimensional magnetic fields. Both magnetic flux densities Br [T] in the radial direction and power density [W/m3] are calculated. It is found that the parameter optimization can increase the power density of LETs to 2.7 times compared with the initial design [Zuo et al, Smart Materials and Structures, v19 n4, 2010], and the double-layer configuration with both radial and axial magnets can improve the power density to 4.7 times, approaching to the energy dissipation rate of traditional oil dampers. As a case study, we investigate its application to energy-harvesting shock absorbers. For a reasonable retrofit size, the LETs with double-layer configuration and both axial and radial NdFeB magnets can provide a damping coefficient of 1138 N.s/m while harvesting 35.5 W power on the external electric load at 0.25 m/s suspension velocity. If the LET is shorten circuit, it can dissipate energy at the rate of 142.0 W, providing of a damping coefficient of 2276 N.s/m. Practical consideration of number of coil phases is also discussed.
Captain Power and Power Quiz: Two New Energy Education Programs.
ERIC Educational Resources Information Center
Niedermeyer, Fred C.; Roberson, Ernest J.
1979-01-01
Describes the development and the testing of two elementary school programs on energy education: "Captain Power" for Grades 2 or 3 and "Power Quiz" for Grades 5 or 6. The programs were tested in classrooms and revised to the point where they will reliably produce high levels of achievement of specified learning outcomes.…
NASA Astrophysics Data System (ADS)
Colin, M.; Basrour, S.; Rufer, L.
2013-05-01
Current version of implantable cardioverter defibrillators (ICDs) and pacemakers consists of a battery-powered pulse generator connected onto the heart through electrical leads inserted through the veins. However, it is known that long-term lead failure may occur and cause a dysfunction of the device. When required, the removal of the failed leads is a complex procedure associated with a potential risk of mortality. As a consequence, the main players in the field of intracardiac implants prepare a next generation of devices: miniaturized and autonomous leadless implants, which could be directly placed inside the heart. In this paper, we discuss the frequency content of a heart vibration spectrum, and the dimensional restrictions in the case of a leadless pacemaker. In combination with the requirements in terms of useable energy, we will present a design study of a resonant piezoelectric scavenger aimed at powering such a device. In particular, we will show how the frequency-volume-energy requirement leads to new challenges in terms of power densities, which are to be addressed through implementation of innovative piezoelectric thick films fabrication processes. This paper also presents the simulation, fabrication and the testing of an ultralow frequency (15Hz) resonant piezoelectric energy harvester prototype. Using both harmonic (50mg) and real heart-induced vibrations, we obtained an output power of 60μW and 10μW respectively. Finally, we will place emphasis on the new constraint represented by the gravitational (orientation) sensitivity inherent to these ultra low frequency resonant energy harvesters.
Vibrational effects on surface energies and band gaps in hexagonal and cubic ice
NASA Astrophysics Data System (ADS)
Engel, Edgar A.; Monserrat, Bartomeu; Needs, Richard J.
2016-07-01
Surface energies of hexagonal and cubic water ice are calculated using first-principles quantum mechanical methods, including an accurate description of anharmonic nuclear vibrations. We consider two proton-orderings of the hexagonal and cubic ice basal surfaces and three proton-orderings of hexagonal ice prism surfaces, finding that vibrations reduce the surface energies by more than 10%. We compare our vibrational densities of states to recent sum frequency generation absorption measurements and identify surface proton-orderings of experimental ice samples and the origins of characteristic absorption peaks. We also calculate zero point quantum vibrational corrections to the surface electronic band gaps, which range from -1.2 eV for the cubic ice basal surface up to -1.4 eV for the hexagonal ice prism surface. The vibrational corrections to the surface band gaps are up to 12% smaller than for bulk ice.
Development of Vibration-Based Piezoelectric Raindrop Energy Harvesting System
NASA Astrophysics Data System (ADS)
Wong, Chin Hong; Dahari, Zuraini
2017-01-01
The trend of finding new means to harvest energy has triggered numerous researches to explore the potential of raindrop energy harvesting. This paper presents an investigation on raindrop energy harvesting which compares the performance of polyvinylidene fluoride (PVDF) cantilever and bridge structure transducers and the development of a raindrop energy harvesting system. The parameters which contribute to the output voltage such as droplet size, droplets released at specific heights and dimensions of PVDF transducers are analyzed. Based on the experimental results, the outcomes have shown that the bridge structure transducer generated a higher voltage than the cantilever. Several dimensions have been tested and it was found that the 30 mm × 4 mm × 25 μm bridge structure transducer generated a relatively high AC open-circuit voltage, which is 4.22 V. The power generated by the bridge transducer is 18 μW across a load of 330 kΩ. The transducer is able to drive up a standard alternative current (AC) to direct current (DC) converter (full-wave bridge rectifier). It generated a DC voltage, V DC of 8.7 mV and 229 pW across a 330 kΩ resistor per drop. It is also capable to generate 9.3 nJ in 20 s from an actual rain event.
Development of Vibration-Based Piezoelectric Raindrop Energy Harvesting System
NASA Astrophysics Data System (ADS)
Wong, Chin Hong; Dahari, Zuraini
2017-03-01
The trend of finding new means to harvest energy has triggered numerous researches to explore the potential of raindrop energy harvesting. This paper presents an investigation on raindrop energy harvesting which compares the performance of polyvinylidene fluoride (PVDF) cantilever and bridge structure transducers and the development of a raindrop energy harvesting system. The parameters which contribute to the output voltage such as droplet size, droplets released at specific heights and dimensions of PVDF transducers are analyzed. Based on the experimental results, the outcomes have shown that the bridge structure transducer generated a higher voltage than the cantilever. Several dimensions have been tested and it was found that the 30 mm × 4 mm × 25 μm bridge structure transducer generated a relatively high AC open-circuit voltage, which is 4.22 V. The power generated by the bridge transducer is 18 μW across a load of 330 kΩ. The transducer is able to drive up a standard alternative current (AC) to direct current (DC) converter (full-wave bridge rectifier). It generated a DC voltage, V DC of 8.7 mV and 229 pW across a 330 kΩ resistor per drop. It is also capable to generate 9.3 nJ in 20 s from an actual rain event.
Energy Storage for the Power Grid
Imhoff, Carl; Vaishnav, Dave
2014-07-01
The iron vanadium redox flow battery was developed by researchers at Pacific Northwest National Laboratory as a solution to large-scale energy storage for the power grid. This technology provides the energy industry and the nation with a reliable, stable, safe, and low-cost storage alternative for a cleaner, efficient energy future.
Teachers Environmental Resource Unit: Energy and Power.
ERIC Educational Resources Information Center
Bemiss, Clair W.
Problems associated with energy production and power are studied in this teacher's guide to better understand the impact of man's energy production on the environment, how he consumes energy, and in what quantities. The resource unit is intended to provide the teacher with basic information that will aid classroom review of these problems. Topics…
Renewable Energy. The Power to Choose.
ERIC Educational Resources Information Center
Deudney, Daniel; Flavin, Christopher
This book, consisting of 13 chapters, charts the progress made in renewable energy in recent years and outlines renewable energy's prospects. Areas addressed include: energy at the crossroads (discussing oil, gas, coal, nuclear power, and the conservation revolution); solar building design; solar collection; sunlight to electricity; wood; energy…
Laser energy converted into electric power
NASA Technical Reports Server (NTRS)
Shimada, K.
1973-01-01
Apparatus verifies concepts of converting laser energy directly into electric energy. Mirror, placed in beam and inclined at angle to it, directs small amount of incident radiation to monitor which establishes precise power levels and other beam characteristics. Second mirror and condensing lens direct bulk of laser energy into laser plasmadynamic converter.
Energy Storage for the Power Grid
Imhoff, Carl; Vaishnav, Dave
2016-07-12
The iron vanadium redox flow battery was developed by researchers at Pacific Northwest National Laboratory as a solution to large-scale energy storage for the power grid. This technology provides the energy industry and the nation with a reliable, stable, safe, and low-cost storage alternative for a cleaner, efficient energy future.
Using powerful vibrators for calibration of seismic traces in nuclear explosion monitoring problems
NASA Astrophysics Data System (ADS)
Glinsky, B.; Kovalevsky, V.; Seleznev, V.; Emanov, A.; Soloviev, V.
2009-04-01
The efficiency of functioning of the International Seismic Monitoring System (ISMS) is connected with the accuracy of the location and identification of a source of seismic waves which can be nuclear explosion. The errors in the determination of the location are caused by local and regional variations of wave hodographs. Empirical approach to solving these problems is to use events for which the locations and times are known, in order to determine a set of corrections to the regional model of wave propagation. The using of powerful vibrators for calibration of seismic traces is a new way in nuclear explosion monitoring problems. Now the 60-100 tons force vibrator can radiate the signals which can be recorded at the distances up to 500 km and can be used for regional calibration of seismic traces. The comparison of the seismic wave fields of powerful vibrators and 100-ton chemical explosion "Omega-3" at the 630-km profile, quarry explosions of the Kuznetsk basin with power from 50 to 700 tons at the distances up to 355 km showed their equivalence in the main types of waves. The paper presents the results of experiments of long-distance recording of seismic signals of powerful vibrators and detailed investigation of the velocity characteristics of the Earth's crust in West Siberia and Altay-Sayan region.
Using powerful vibrators for calibration of seismic traces in nuclear explosion monitoring problems.
NASA Astrophysics Data System (ADS)
Glinsky, B.; Kovalevsky, V.; Seleznev, V.; Emanov, A.; Soloviev, V.
2009-04-01
The efficiency of functioning of the International Seismic Monitoring System (ISMS) is connected with the accuracy of the location and identification of a source of seismic waves which can be nuclear explosion. The errors in the determination of the location are caused by local and regional variations of wave hodographs. Empirical approach to solving these problems is to use events for which the locations and times are known, in order to determine a set of corrections to the regional model of wave propagation. The using of powerful vibrators for calibration of seismic traces is a new way in nuclear explosion monitoring problems. Now the 60-100 tons force vibrator can radiate the signals which can be recorded at the distances up to 500 km and can be used for regional calibration of seismic traces. The comparison of the seismic wave fields of powerful vibrators and 100-ton chemical explosion "Omega-3" at the 630-km profile, quarry explosions of the Kuznetsk basin with power from 50 to 700 tons at the distances up to 355 km showed their equivalence in the main types of waves. The paper presents the results of experiments of long-distance recording of seismic signals of powerful vibrators and detailed investigation of the velocity characteristics of the Earth's crust in West Siberia and Altay-Sayan region.
Effect of Vibration Training on Anaerobic Power and Quardroceps Surface EMG in Long Jumpers
ERIC Educational Resources Information Center
Liu, Bin; Luo, Jiong
2015-01-01
Objective: To explore the anaerobic power and surface EMG (sEMG) of quardrocep muscle in lower extremities after single vibration training intervention. Methods: 8 excellent male long jumpers voluntarily participated in this study. Four intervention modes were devised, including high frequency high amplitude (HFHA,30Hz,6mm), low frequency low…
A fail-safe magnetorheological energy absorber for shock and vibration isolation
NASA Astrophysics Data System (ADS)
Bai, Xian-Xu; Wereley, Norman M.
2014-05-01
Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control.
A fail-safe magnetorheological energy absorber for shock and vibration isolation
Bai, Xian-Xu; Wereley, Norman M.
2014-05-07
Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control.
Saffar, Saber; Abdullah, Amir
2014-01-01
The acoustic impedances of matching layers, their internal loss and vibration amplitude are the most important and influential parameters in the performance of high power airborne ultrasonic transducers. In this paper, the optimum acoustic impedances of the transducer matching layers were determined by using a genetic algorithm, the powerful tool for optimizating domain. The analytical results showed that the vibration amplitude increases significantly for low acoustic impedance matching layers. This enhancement is maximum and approximately 200 times higher for the last matching layer where it has the same interface with the air than the vibration amplitude of the source, lead zirconate titanate-pizo electric while transferring the 1 kW is desirable. This large amplitude increases both mechanical failure and temperature of the matching layers due to the internal loss of the matching layers. It has analytically shown that the temperature in last matching layer with having the maximum vibration amplitude is high enough to melt or burn the matching layers. To verify suggested approach, the effect of the amplitude of vibration on the induced temperature has been investigated experimentally. The experimental results displayed good agreement with the theoretical predictions.
NASA Astrophysics Data System (ADS)
Tobiason, J. D.; Utz, A. L.; Crim, F. F.
1994-07-01
Vibrational overtone excitation followed by laser-induced fluorescence detection allows the direct measurement of rotationally resolved vibrational energy transfer rates in highly vibrationally excited acetylene molecules. We detect transfer from the initial, even rotational states Ji=0-22 of 3ν3 (ν˜0=9640 cm-1) to the nearly isoenergetic final state Jf=4 of ν1+ν2+ν3+2ν4, l=0 (ν˜0=9668 cm-1). For these pathways, we observe changes in energy of up to ‖ΔE‖=530 cm-1 (≊2.5 kT) and in angular momentum quantum number of up to ‖ΔJ‖=18 in a single collision, and we measure state-to-state rate constants of about 0.1 μs-1Torr-1 (160 collisions). Measurements under single collision conditions ensure that the vibrational relaxation is free of any rotational equilibration. By applying detailed balance and summing the resulting reverse rate constants, we obtain a total rate constant of 1.3 μs-1Torr-1 (13 collisions) for transfer from ν1+ν2+ν3+2ν4, l=0, Jf=4 to all final rotational states in 3ν3. The energy transfer rate between two specific rovibrational states decreases exponentially with increasing energy difference. The vibrational relaxation does not have a strong angular momentum dependence in general, but transfer from the initial rotational states 3ν3, J=16, and J=20 is anomalously fast. The Fermi resonance of 3ν3 and ν1+ν2+ν3+2ν4, l=0 appears to enhance collisional transfer between the pair by a factor of 10 or more over that for uncoupled levels, and the anomalously fast transfer from initial states 3ν3, J=16 and 20 is probably due to their relatively strong, rotation-specific intramolecular coupling with other nearby, unobserved vibrational states.
Energy harvesting to power embedded condition monitoring hardware
NASA Astrophysics Data System (ADS)
Farinholt, Kevin; Brown, Nathan; Siegel, Jake; McQuown, Justin; Humphris, Robert
2015-04-01
The shift toward condition-based monitoring is a key area of research for many military, industrial, and commercial customers who want to lower the overall operating costs of capital equipment and general facilities. Assessing the health of rotating systems such as gearboxes, bearings, pumps and other actuation systems often rely on the need for continuous monitoring to capture transient signals that are evidence of events that could cause (i.e. cavitation), or be the result of (i.e. spalling), damage within a system. In some applications this can be accomplished using line powered analyzers, however for wide-spread monitoring, the use of small-scale embedded electronic systems are more desirable. In such cases the method for powering the electronics becomes a significant design factor. This work presents a multi-source energy harvesting approach meant to provide a robust power source for embedded electronics, capturing energy from vibration, thermal and light sources to operate a low-power sensor node. This paper presents the general design philosophy behind the multi-source harvesting circuit, and how it can be extended from powering electronics developed for periodic monitoring to sensing equipment capable of providing continuous condition-based monitoring.
NASA Technical Reports Server (NTRS)
Tessarzik, J. M.; Chiang, T.; Badgley, R. H.
1973-01-01
The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.
NASA Astrophysics Data System (ADS)
Kuo, Chun-Liang; Lin, Shun-Chiu; Wu, Wen-Jong
2016-10-01
This paper presents the development of a bimorph microelectromechanical system (MEMS) generator for vibration energy harvesting. The bimorph generator is in cantilever beam structure formed by laminating two lead zirconate titanate thick-film layers on both sides of a stainless steel substrate. Aiming to scavenge vibration energy efficiently from the environment and transform into useful electrical energy, the two piezoelectric layers on the device can be poled for serial and parallel connections to enhance the output voltage or output current respectively. In addition, a tungsten proof mass is bonded at the tip of the device to adjust the resonance frequency. The experimental result shows superior performance the generator. At the 0.5 g base excitation acceleration level, the devices pooled for serial connection and the device poled for parallel connection possess an open-circuit output voltage of 11.6 VP-P and 20.1 VP-P, respectively. The device poled for parallel connection reaches a maximum power output of 423 μW and an output voltage of 15.2 VP-P at an excitation frequency of 143.4 Hz and an externally applied based excitation acceleration of 1.5 g, whereas the device poled serial connection achieves a maximum power output of 413 μW and an output voltage of 33.0 VP-P at an excitation frequency of 140.8 Hz and an externally applied base excitation acceleration of 1.5 g. To demonstrate the feasibility of the MEMS generator for real applications, we finished the demonstration of a self-powered Bluetooth low energy wireless temperature sensor sending readings to a smartphone with only the power from the MEMS generator harvesting from vibration.
NASA Technical Reports Server (NTRS)
Mckenzie, R. L.
1975-01-01
A semiclassical model of the inelastic collision between a vibrationally excited anharmonic oscillator and a structureless atom was used to predict the variation of thermally averaged vibration-translation rate coefficients with temperature and initial-state quantum number. Multiple oscillator states were included in a numerical solution for collinear encounters. The results are compared with CO-He experimental values for both ground and excited initial states using several simplified forms of the interaction potential. The numerical model was also used as a basis for evaluating several less complete but analytic models. Two computationally simple analytic approximations were found that successfully reproduced the numerical rate coefficients for a wide range of molecular properties and collision partners. Their limitations were also identified. The relative rates of multiple-quantum transitions from excited states were evaluated for several molecular types.
NASA Technical Reports Server (NTRS)
Mckenzie, R. L.
1976-01-01
A semiclassical model of the inelastic collision between a vibrationally excited anharmonic oscillator and a structureless atom is used to predict the variation of thermally averaged vibrational-translational rate coefficients with temperature and initial-state quantum number. Multiple oscillator states are included in a numerical solution for collinear encounters. The results are compared with CO-He experimental values for both ground and excited initial states using several simplified forms of the interaction potential. The numerical model is also used as a basis for evaluating several less complete, but analytic, models. Two computationally simple analytic approximations are found that successfully reproduce the numerical rate coefficients for a wide range of molecular properties and collision partners. Their limitations are identified, and the relative rates of multiple-quantum transitions from excited states are evaluated for several molecular types.
NASA Astrophysics Data System (ADS)
Bykov, A. D.; Duchko, A. N.
2016-05-01
The Rayleigh-Schrödinger perturbation theory of high orders and the algebraic Padé-Hermite approximants are used to determine the singular points of a vibrational energy function of the formaldehyde molecule dependent on a complex perturbation parameter as on the argument. It is shown that the Fermi, Darling-Dennison, and other higher-order vibrational resonances are related to Katz's points—common branch points on the complex plane of the energy of two vibrational states. Analysis of Katz's points that connect different vibrational states allows one to reveal essential resonance perturbations, to introduce an additional classification for them, and to determine the polyad structure of an energy spectrum.
Power Measurement Methods for Energy Efficient Applications
Calandrini, Guilherme; Gardel, Alfredo; Bravo, Ignacio; Revenga, Pedro; Lázaro, José L.; Toledo-Moreo, F. Javier
2013-01-01
Energy consumption constraints on computing systems are more important than ever. Maintenance costs for high performance systems are limiting the applicability of processing devices with large dissipation power. New solutions are needed to increase both the computation capability and the power efficiency. Moreover, energy efficient applications should balance performance vs. consumption. Therefore power data of components are important. This work presents the most remarkable alternatives to measure the power consumption of different types of computing systems, describing the advantages and limitations of available power measurement systems. Finally, a methodology is proposed to select the right power consumption measurement system taking into account precision of the measure, scalability and controllability of the acquisition system. PMID:23778191
NASA Astrophysics Data System (ADS)
Yuan, Xuan; Changgeng, Shuai; Yan, Gao; Zhenghong, Zhao
2016-09-01
This paper reviews recent advances in vibration energy harvesting with particular emphasis on the solutions by using dielectric electroactive polymers (DEAPs) and piezoelectric materials. These smart materials are in essence capable of converting wasted vibration energy in the environment to usable electrical energy. Much previous researches have been devoted to studying the technology of harvesting mechanical energy using piezoelectric materials. The recent introduction of the DEAPs that exhibits large displacements under electric activation has led to their consideration as promising replacement for conventional piezoelectric materials. The properties of the two materials are described in this paper together with a comparison of their performance in relation with energy harvesting. Finally comparisons are made in the applications of vibration energy harvesting using these two materials. This paper has been written with reference to a large number of published papers listed in the reference section.
Rotation vibration energy level clustering in the XB1 ground electronic state of PH2
NASA Astrophysics Data System (ADS)
Yurchenko, S. N.; Thiel, W.; Jensen, Per; Bunker, P. R.
2006-10-01
We use previously determined potential energy surfaces for the Renner-coupled XB1 and AA1 electronic states of the phosphino (PH 2) free radical in a calculation of the energies and wavefunctions of highly excited rotational and vibrational energy levels of the X˜ state. We show how spin-orbit coupling, the Renner effect, rotational excitation, and vibrational excitation affect the clustered energy level patterns that occur. We consider both 4-fold rotational energy level clustering caused by centrifugal distortion, and vibrational energy level pairing caused by local mode behaviour. We also calculate ab initio dipole moment surfaces for the X˜ and A˜ states, and the X˜-A˜ transition moment surface, in order to obtain spectral intensities.
NASA Astrophysics Data System (ADS)
Chen, Shih-Jui; Wu, Jia-Yin
2016-09-01
A vibration structure with two-degrees-of-freedom is proposed to increase the usable bandwidth of a micromachined electromagnetic energy harvester. Compared with the structure of a pure cantilever harvester, the proposed structure is formed by integrating a spiral diaphragm into a U-shaped cantilever diaphragm. By performing finite element analysis, the resonance frequencies of the two diaphragms are designed with a slight shift, both lower than 300 Hz. In addition, to achieve output bandwidth broadening, electroplated copper coils on the spiral and the U-shaped cantilever are coupled and the connection sequences of the coupled coils are arranged such that single- or duo-mode tuning of the energy harvester can be realized. The harvester delivers powers of 22.1 and 21.5 nW at two resonance frequencies of 211 and 274 Hz, respectively, in the duo-mode operation. The proposed spiral-cantilever coupled energy harvester has lower resonance frequencies and broader bandwidth than a pure cantilever-type harvester of equal area, and can therefore harvest more energy from the environment.
Vibrational energy on surfaces: Ultrafast flash-thermal conductance of molecular monolayers
NASA Astrophysics Data System (ADS)
Dlott, Dana
2008-03-01
Vibrational energy flow through molecules remains a perennial problem in chemical physics. Usually vibrational energy dynamics are viewed through the lens of time-dependent level populations. This is natural because lasers naturally pump and probe vibrational transitions, but it is also useful to think of vibrational energy as being conducted from one location in a molecule to another. We have developed a new technique where energy is driven into a specific part of molecules adsorbed on a metal surface, and ultrafast nonlinear coherent vibrational spectroscopy is used to watch the energy arrive at another part. This technique is the analog of a flash thermal conductance apparatus, except it probes energy flow with angstrom spatial and femtosecond temporal resolution. Specific examples to be presented include energy flow along alkane chains, and energy flow into substituted benzenes. Ref: Z. Wang, J. A. Carter, A. Lagutchev, Y. K. Koh, N.-H. Seong, D. G. Cahill, and D. D. Dlott, Ultrafast flash thermal conductance of molecular chains, Science 317, 787-790 (2007). This material is based upon work supported by the National Science Foundation under award DMR 0504038 and the Air Force Office of Scientific Research under award FA9550-06-1-0235.
Energy Decisions: Is Solar Power the Solution?
ERIC Educational Resources Information Center
Childress, Vincent W.
2011-01-01
People around the world are concerned about affordable energy. It is needed to power the global economy. Petroleum-based transportation and coal-fired power plants are economic prime movers fueling the global economy, but coal and gasoline are also the leading sources of air pollution. Both of these sources produce greenhouse gases and toxins.…
Power Technologies Energy Data Book - Fourth Edition
Aabakken, J.
2006-08-01
This report, prepared by NREL's Strategic Energy Analysis Center, includes up-to-date information on power technologies, including complete technology profiles. The data book also contains charts on electricity restructuring, power technology forecasts, electricity supply, electricity capability, electricity generation, electricity demand, prices, economic indicators, environmental indicators, and conversion factors.
SPS Energy Conversion Power Management Workshop
NASA Technical Reports Server (NTRS)
1980-01-01
Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.
TARDEC’s Power and Energy Vision
2009-04-27
Hybrid Electric (HE) fleet. High-power, high-energy density, Li-ion batteries are being designed for use in Hybrid Electric Vehicle (HEV) propulsion...short-circuit protection device used to protect equipment when military vehicles increasingly exceed the electrical power generation capability...genera- tion and usage, addresses both approaches. It is, therefore, a systems engineering approach to the efficient use of electrical power on vehicle
Coal and nuclear power: Illinois' energy future
Not Available
1982-01-01
This conference was sponsored by the Energy Resources Center, University of Illinois at Chicago; the US Department of Energy; the Illinois Energy Resources Commission; and the Illinois Department of Energy and Natural Resources. The theme for the conference, Coal and Nuclear Power: Illinois' Energy Future, was based on two major observations: (1) Illinois has the largest reserves of bituminous coal of any state and is surpassed in total reserves only by North Dakota, and Montana; and (2) Illinois has made a heavy commitment to the use of nuclear power as a source of electrical power generation. Currently, nuclear power represents 30% of the electrical energy produced in the State. The primary objective of the 1982 conference was to review these two energy sources in view of the current energy policy of the Reagan Administration, and to examine the impact these policies have on the Midwest energy scene. The conference dealt with issues unique to Illinois as well as those facing the entire nation. A separate abstract was prepared for each of the 30 individual presentations.
A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot.
Liu, Yingxiang; Chen, Weishan; Liu, Junkao; Shi, Shengjun
2010-08-01
A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot was proposed in this paper. The stator of proposed motor contains a horizontal transducer and a vertical transducer. Longitudinal vibrations are superimposed in the stator and generate an elliptical trajectory at the driving foot. The sensitivity analysis of structural parameters to the resonance frequencies of two working modes of the stator was performed using the finite element method. The resonance frequencies of two working modes were degenerated by adjusting the structural parameters. The vibration characteristics of stator were studied and discussed. A prototype motor was fabricated and measured. Typical output of the prototype is a no-load speed of 1160 mm/s and maximum thrust force of 20 N at a voltage of 200 V(rms).
NASA Astrophysics Data System (ADS)
Fujisaki, Hiroshi; Yagi, Kiyoshi; Kikuchi, Hiroto; Takami, Toshiya; Stock, Gerhard
2017-01-01
Performing comprehensive quantum-chemical calculations, a vibrational Hamiltonian of acetylbenzonitrile is constructed, on the basis of which a quantum-mechanical "tier model" is developed that describes the vibrational dynamics following excitation of the CN stretch mode. Taking into account 36 vibrational modes and cubic and quartic anharmonic couplings between up to three different modes, the tier model calculations are shown to qualitatively reproduce the main findings of the experiments of Rubtsov and coworkers (2011), including the energy relaxation of the initially excited CN mode and the structure-dependent vibrational transport. Moreover, the calculations suggest that the experimentally measured cross-peak among the CN and CO modes does not correspond to direct excitation of the CO normal mode but rather reflects excited low-frequency vibrations that anharmonically couple to the CO mode. Complementary quasiclassical trajectory calculations are found to be in good overall agreement with the quantum calculations.
Power conversion from environmentally scavenged energy sources.
Druxman, Lee Daniel
2007-09-01
As the power requirements for modern electronics continue to decrease, many devices which were once dependent on wired power are now being implemented as portable devices operating from self-contained power sources. The most prominent source of portable power is the electrochemical battery, which converts chemical energy into electricity. However, long lasting batteries require large amounts of space for chemical storage, and inevitably require replacement when the chemical reaction no longer takes place. There are many transducers and scavenging energy sources (SES) that are able to exploit their environment to generate low levels of electrical power over a long-term time period, including photovoltaic cells, thermoelectric generators, thermionic generators, and kinetic/piezoelectric power generators. This generated power is sustainable as long as specific environmental conditions exist and also does not require the large volume of a long lifetime battery. In addition to the required voltage generation, stable power conversion requires excess energy to be efficiently stored in an ultracapacitor or similar device and monitoring control algorithms to be implemented, while computer modeling and simulation can be used to complement experimental testing. However, building an efficient and stable power source scavenged from a varying input source is challenging.
Mems-Based Waste Vibration and Acoustic Energy Harvesters
2014-12-01
Timothy J. Householder Approved by: Dragoslav Grbovic Thesis Advisor Bruce Denardo Co-Advisor Andres Larraza Chair, Department...MotionPro X3 high-speed camera with a Carl Zeiss MAKRO-PLANAR T*, 2-100 mm, ZF.2 macro-lens was used to observe the vibrational mode at 3910 frames
Micromachined cantilevers-on-membrane topology for broadband vibration energy harvesting
NASA Astrophysics Data System (ADS)
Jia, Yu; Du, Sijun; Seshia, Ashwin A.
2016-12-01
The overwhelming majority of microelectromechanical piezoelectric vibration energy harvesting topologies have been based on cantilevers, doubly-clamped beams or basic membranes. While these conventional designs offer simplicity, their broadband responses have been limited thus far. This paper investigates the feasibility of a new integrated cantilevers-on-membrane design that explores the optimisation of piezoelectric strain distribution and improvement of the broadband power output. While a classic membrane has the potential to offer a broader resonant peak than its cantilever counterpart, the inclusion of a centred proof mass compromises its otherwise high strain energy regions. The proposed topology addresses this issue by relocating the proof mass onto subsidiary cantilevers and combines the merits of both the membrane and the cantilever designs. Numerical simulations, constructed using fitted values based on finite element models, were used to investigate the broadband response of the proposed design in contrast to a classic plain membrane. Experimentally, when subjected to a band-limited white noise excitation, the new cantilevers-on-membrane harvester exhibited nearly two fold power output enhancement when compared to a classic plain membrane harvester of a comparable size.
NASA Astrophysics Data System (ADS)
Khbeis, Michael Tawfik
Scavenging energy from environmental sources is an active area of research to enable remote sensing and microsystems applications. Furthermore, as energy demands soar, there is a significant need to explore new sources and curb waste. Vibration energy scavenging is one environmental source for remote applications and a candidate for recouping energy wasted by mechanical sources that can be harnessed to monitor and optimize operation of critical infrastructure (e.g. Smart Grid). Current vibration scavengers are limited by volume and ancillary requirements for operation such as control circuitry overhead and battery sources. This dissertation, for the first time, reports a mass producible hybrid energy scavenger system that employs both piezoelectric and electrostatic transduction on a common MEMS device. The piezoelectric component provides an inherent feedback signal and pre-charge source that enables electrostatic scavenging operation while the electrostatic device provides the proof mass that enables low frequency operation. The piezoelectric beam forms the spring of the resonant mass-spring transducer for converting vibration excitation into an AC electrical output. A serially poled, composite shim, piezoelectric bimorph produces the highest output rectified voltage of over 3.3V and power output of 145muW using ¼ g vibration acceleration at 120Hz. Considering solely the volume of the piezoelectric beam and tungsten proof mass, the volume is 0.054cm3, resulting in a power density of 2.68mW/cm3. Incorporation of a simple parallel plate structure that provides the proof mass for low frequency resonant operation in addition to cogeneration via electrostatic energy scavenging provides a 19.82 to 35.29 percent increase in voltage beyond the piezoelectric generated DC rails. This corresponds to approximately 2.1nW additional power from the electrostatic scavenger component and demonstrates the first instance of hybrid energy scavenging using both piezoelectric and
Simulating Energy Relaxation in Pump-Probe Vibrational Spectroscopy of Hydrogen-Bonded Liquids.
Dettori, Riccardo; Ceriotti, Michele; Hunger, Johannes; Melis, Claudio; Colombo, Luciano; Donadio, Davide
2017-03-14
We introduce a nonequilibrium molecular dynamics simulation approach, based on the generalized Langevin equation, to study vibrational energy relaxation in pump-probe spectroscopy. A colored noise thermostat is used to selectively excite a set of vibrational modes, leaving the other modes nearly unperturbed, to mimic the effect of a monochromatic laser pump. Energy relaxation is probed by analyzing the evolution of the system after excitation in the microcanonical ensemble, thus providing direct information about the energy redistribution paths at the molecular level and their time scale. The method is applied to hydrogen-bonded molecular liquids, specifically deuterated methanol and water, providing a robust picture of energy relaxation at the molecular scale.
Fiscalini Farms Renewable Energy Power Generation Project
2009-02-01
Funded by the American Recovery and Reinvestment Act of 2009 Fiscalini Farms L.P., in collaboration with University of the Pacific, Biogas Energy, Inc., and the University of California at Berkeley will measure and analyze the efficiency and regulatory compliance of a renewable energy system for power generation. The system will utilize digester gas from an anaerobic digester located at the Fiscalini Farms dairy for power generation with a reciprocating engine. The project will provide power, efficiency, emissions, and cost/benefit analysis for the system and evaluate its compliance with federal and California emissions standards.
Space solar power - An energy alternative
NASA Technical Reports Server (NTRS)
Johnson, R. W.
1978-01-01
The space solar power concept is concerned with the use of a Space Power Satellite (SPS) which orbits the earth at geostationary altitude. Two large symmetrical solar collectors convert solar energy directly to electricity using photovoltaic cells woven into blankets. The dc electricity is directed to microwave generators incorporated in a transmitting antenna located between the solar collectors. The antenna directs the microwave beam to a receiving antenna on earth where the microwave energy is efficiently converted back to dc electricity. The SPS design promises 30-year and beyond lifetimes. The SPS is relatively pollution free as it promises earth-equivalence of 80-85% efficient ground-based thermal power plant.
Ab initio potential energy surface and vibration-rotation energy levels of sulfur dioxide.
Koput, Jacek
2017-05-05
An accurate potential energy surface of sulfur dioxide, SO2 , in its ground electronic state X∼ 1A1 has been determined from ab initio calculations using the coupled-cluster approach in conjunction with the correlation-consistent basis sets up to septuple-zeta quality. The results obtained with the conventional and explicitly correlated coupled-cluster methods are compared. The role of the core-electron correlation, higher-order valence-electron correlation, scalar relativistic, and adiabatic effects in determining the structure and dynamics of the SO2 molecule is discussed. The vibration-rotation energy levels of the (32) SO2 and (34) SO2 isotopologues were predicted using a variational approach. It was shown that the inclusion of the aforementioned effects was mandatory to attain the "spectroscopic" accuracy. © 2017 Wiley Periodicals, Inc.
Power conditioning system for energy sources
Mazumder, Sudip K.; Burra, Rajni K.; Acharya, Kaustuva
2008-05-13
Apparatus for conditioning power generated by an energy source includes an inverter for converting a DC input voltage from the energy source to a square wave AC output voltage, and a converter for converting the AC output voltage from the inverter to a sine wave AC output voltage.
Breezy Power: From Wind to Energy
ERIC Educational Resources Information Center
Claymier, Bob
2009-01-01
This lesson combines the science concepts of renewable energy and producing electricity with the technology concepts of design, constraints, and technology's impact on the environment. Over five class periods, sixth-grade students "work" for a fictitious power company as they research wind as an alternative energy source and design and test a…
Fluid Power Systems. Energy Technology Series.
ERIC Educational Resources Information Center
Center for Occupational Research and Development, Inc., Waco, TX.
This course in fluid power systems is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in company-sponsored…
Mechanism of vibrational energy dissipation of free OH groups at the air–water interface
Hsieh, Cho-Shuen; Campen, R. Kramer; Okuno, Masanari; Backus, Ellen H. G.; Nagata, Yuki; Bonn, Mischa
2013-01-01
Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air–water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air–H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces. PMID:24191016
Mechanism of vibrational energy dissipation of free OH groups at the air-water interface.
Hsieh, Cho-Shuen; Campen, R Kramer; Okuno, Masanari; Backus, Ellen H G; Nagata, Yuki; Bonn, Mischa
2013-11-19
Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air-water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air-H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces.
Vibration interaction in a multiple flywheel system
NASA Astrophysics Data System (ADS)
Firth, Jordan; Black, Jonathan
2012-03-01
This paper investigates vibration interaction in a multiple flywheel system. Flywheels can be used for kinetic energy storage in a satellite Integrated Power and Attitude Control System (IPACS). One hitherto unstudied problem with IPACS is vibration interaction between multiple unbalanced wheels. This paper uses a linear state-space dynamics model to study the impact of vibration interaction. Specifically, imbalance-induced vibration inputs in one flywheel rotor are used to cause a resonant whirling vibration in another rotor. Extra-synchronous resonant vibrations are shown to exist, but with damping modeled the effect is minimal. Vibration is most severe when both rotors are spinning in the same direction.
Voltage tuning of vibrational mode energies in single-molecule junctions
Li, Yajing; Doak, Peter; Kronik, Leeor; Neaton, Jeffrey B.; Natelson, Douglas
2014-01-01
Vibrational modes of molecules are fundamental properties determined by intramolecular bonding, atomic masses, and molecular geometry, and often serve as important channels for dissipation in nanoscale processes. Although single-molecule junctions have been used to manipulate electronic structure and related functional properties of molecules, electrical control of vibrational mode energies has remained elusive. Here we use simultaneous transport and surface-enhanced Raman spectroscopy measurements to demonstrate large, reversible, voltage-driven shifts of vibrational mode energies of C60 molecules in gold junctions. C60 mode energies are found to vary approximately quadratically with bias, but in a manner inconsistent with a simple vibrational Stark effect. Our theoretical model instead suggests that the mode shifts are a signature of bias-driven addition of electronic charge to the molecule. These results imply that voltage-controlled tuning of vibrational modes is a general phenomenon at metal–molecule interfaces and is a means of achieving significant shifts in vibrational energies relative to a pure Stark effect. PMID:24474749
Energy Servers Deliver Clean, Affordable Power
NASA Technical Reports Server (NTRS)
2010-01-01
K.R. Sridhar developed a fuel cell device for Ames Research Center, that could use solar power to split water into oxygen for breathing and hydrogen for fuel on Mars. Sridhar saw the potential of the technology, when reversed, to create clean energy on Earth. He founded Bloom Energy, of Sunnyvale, California, to advance the technology. Today, the Bloom Energy Server is providing cost-effective, environmentally friendly energy to a host of companies such as eBay, Google, and The Coca-Cola Company. Bloom's NASA-derived Energy Servers generate energy that is about 67-percent cleaner than a typical coal-fired power plant when using fossil fuels and 100-percent cleaner with renewable fuels.
Saving Energy Through Advanced Power Strips (Poster)
Christensen, D.
2013-10-01
Advanced Power Strips (APS) look just like ordinary power strips, except that they have built-in features that are designed to reduce the amount of energy used by many consumer electronics. There are several different types of APSs on the market, but they all operate on the same basic principle of shutting off the supply power to devices that are not in use. By replacing your standard power strip with an APS, you can signifcantly cut the amount of electricity used by your home office and entertainment center devices, and save money on your electric bill. This illustration summarizes the different options.
NASA Astrophysics Data System (ADS)
Furumachi, S.; Ueno, T.
2016-04-01
We study magnetostrictive vibration based power generator using iron-gallium alloy (Galfenol). The generator is advantages over conventional, such as piezoelectric material in the point of high efficiency highly robust and low electrical impedance. Generally, the generator exhibits maximum power when its resonant frequency matches the frequency of ambient vibration. In other words, the mismatch of these frequencies results in significant decrease of the output. One solution is making the spring characteristics nonlinear using magnetic force, which distorts the resonant peak toward higher or lower frequency side. In this paper, vibrational generator consisting of Galfenol plate of 6 by 0.5 by 13 mm wound with coil and U shape-frame accompanied with plates and pair of permanent magnets was investigated. The experimental results show that lean of resonant peak appears attributed on the non-linear spring characteristics, and half bandwidth with magnets is 1.2 times larger than that without. It was also demonstrated that the addition of proof mass is effective to increase the sensitivity but also the bandwidth. The generator with generating power of sub mW order is useful for power source of wireless heath monitoring for bridge and factory machine.
Modified relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons
Dunkelberger, A. D.; Spann, B. T.; Fears, K. P.; Simpkins, B. S.; Owrutsky, J. C.
2016-01-01
Coupling vibrational transitions to resonant optical modes creates vibrational polaritons shifted from the uncoupled molecular resonances and provides a convenient way to modify the energetics of molecular vibrations. This approach is a viable method to explore controlling chemical reactivity. In this work, we report pump–probe infrared spectroscopy of the cavity-coupled C–O stretching band of W(CO)6 and the direct measurement of the lifetime of a vibration-cavity polariton. The upper polariton relaxes 10 times more quickly than the uncoupled vibrational mode. Tuning the polariton energy changes the polariton transient spectra and relaxation times. We also observe quantum beats, so-called vacuum Rabi oscillations, between the upper and lower vibration-cavity polaritons. In addition to establishing that coupling to an optical cavity modifies the energy-transfer dynamics of the coupled molecules, this work points out the possibility of systematic and predictive modification of the excited-state kinetics of vibration-cavity polariton systems. PMID:27874010
NASA Astrophysics Data System (ADS)
Zhu, Bing; Han, Jiayi; Zhao, Jian; Deng, Weiwen
2017-04-01
Intelligent tires are essentially a data acquisition system based on a number of complex intelligent sensors inside the tire. Intelligent tires which are capable of boosting the performance of the vehicle have the key problem of energy supply. A practical energy harvester was here designed to support the electric equipment in the intelligent tires and make it feasible for them to work steadily and constantly. This harvester takes the centrifugal force caused by the rotation of the wheel, which could affect the resonance frequency of the piezoelectric cantilever, into account. First, the vibration characteristics of the wheel were analyzed by road test, and the optimal arrangement for vibration energy usage was determined. Then, a piezoelectric vibration energy harvester was designed according to a series of formulas that took the effect of centrifugal force on resonance frequency into account. Finally, a road test was carried out to test the generated energy of the energy harvester excited by the vibration of the wheel. The results showed that the electric power meets the need of general low-power consumption triaxial accelerometers used in intelligent tires.
ENIDINE: Vibration and seismic isolation technologies for power generation station applications
Zemanek, T.A.
1994-12-31
ENIDINE Inc. is a world leader in the design and manufacture of shock and vibration mounts. Founded in 1966, the company has two manufacturing facilities, employs over 300 people and supports a worldwide network of distributors and representatives. ENIDINE Inc. is part of the ENIDINE Corporate Group which owns a number of companies that design and manufacture Hydraulic/Pneumatic cylinders, Electromechanical devices, Hydraulic Control Valves and a number of Industrial Distribution companies throughout Europe. In total, the ENIDINE Corporate Group has over 900 employees with annual sales of over $100 million. ENIDINE shock and vibration mounts are used to isolate the vibration of missiles from their guidance systems, pumps from hospital operating equipment and off shore oil rigs, from the shock energy of waves in the North Sea. ENIDINE products can be found on all Boeing and McDonnell Douglas aircraft, as well as many electronic and weapons systems on board Navy ships.
Ostasevicius, Vytautas; Janusas, Giedrius; Milasauskaite, Ieva; Zilys, Mindaugas; Kizauskiene, Laura
2015-01-01
This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4–4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation. PMID:26029948
NASA Astrophysics Data System (ADS)
Nakano, K.; Su, D.; Zheng, R.; Cartmell, M.
2016-09-01
Vibrational energy harvesters are often excited by band-limited noise excitations. In this paper, the influence of the stiffness nonlinearity on the transduction of the energy harvester and the relative performance of linear, monostable hardening-type and bistable energy harvesters are compared and investigated. The performance is experimentally compared under band-limited noise excitations of different levels, bandwidths, and centre frequencies at first. The rms output power delivered to the same load resistance is measured and compared under the same excitation levels, which indicts the constant electrical damping level. It is shown that the effect of nonlinearities is strongly dependent on the excitation parameters. Under a moderate excitation level it is shown that the monostable hardening-type oscillator performs worse than its linear counterpart under band-limited excitation. However, the results also illustrate that for the most part of the frequency and bandwidth range considered, the bistable harvester can outperforms the linear variant but for around the peak output area. Moreover, the comparison is also numerically conducted with the consideration of the optimised electrical damping level and the displacement constraint of the device. General conclusions are drawn based on the experimental observations.
The thermal effects on high-frequency vibration of beams using energy flow analysis
NASA Astrophysics Data System (ADS)
Zhang, Wenbo; Chen, Hualing; Zhu, Danhui; Kong, Xiangjie
2014-04-01
In this paper, the energy flow analysis (EFA) method is developed to predict the high-frequency response of beams in a thermal environment, which is a topic of concern in aerospace and automotive industries. The temperature load applied on the structures can generate thermal stresses and change material properties. The wavenumber and group velocity associated with the in-plane axial force arising from thermal stresses are included in the derivation of the governing energy equation, and the input power is obtained from the derived effective bending stiffness. In addition, effect of temperature-dependent material properties is considered in the EFA model. To verify the proposed formulation, numerical simulations are performed for a pinned-pinned beam in a uniform thermal environment. The EFA results are compared with the modal solutions for various frequencies and damping loss factors, and good correlations are observed. The results show that the spatial distributions and levels of energy density can be affected by the thermal effects, and the vibration response of beams increases with temperature.
Spectroscopic probes of vibrationally excited molecules at chemically significant energies
Rizzo, T.R.
1993-04-01
Infrared-optical double resonance is being used to study the unimolecular dissociation dynamics of hydrazoic acid (HN[sub 3]). 6[nu][sub NH] vibrational overtone excitation spectra are given for HN[sub 3]. Work was begun to determine the feasibility of extending the infrared-optical double resonance photofragment spectroscopy to small free radicals, and to be able to monitor atomic dissociation fragments via laser induced fluorescence in the VUV spectrum. 1 fig.
Vibration Monitoring for Predictive Maintenance in Central Energy Plants
1993-09-01
D: Vibration Coupling Between Machines (or Individual Machine Components) 45 APPENDIX E: Balancing of Machine Components 46 APPENDIX F: Alignment of...Appendix F details specific techniques for aligning machines. Some common techniques for correcting misalignment are: 1. Laser-optic alignment 2...Strain gage alignment 3. Dial indicator alignment . Eccentricity Eccentricity refers to the condition where the center line of a rotor does not coincide
Fedorov, Dmitry A.; Varganov, Sergey A.; Derevianko, Andrei
2014-05-14
We calculate the potential energy curves, the permanent dipole moment curves, and the lifetimes of the ground and excited vibrational states of the heteronuclear alkali dimers XY (X, Y = Li, Na, K, Rb, Cs) in the X{sup 1}Σ{sup +} electronic state using the coupled cluster with singles doubles and triples method. All-electron quadruple-ζ basis sets with additional core functions are used for Li and Na, and small-core relativistic effective core potentials with quadruple-ζ quality basis sets are used for K, Rb, and Cs. The inclusion of the coupled cluster non-perturbative triple excitations is shown to be crucial for obtaining the accurate potential energy curves. A large one-electron basis set with additional core functions is needed for the accurate prediction of permanent dipole moments. The dissociation energies are overestimated by only 14 cm{sup −1} for LiNa and by no more than 114 cm{sup −1} for the other molecules. The discrepancies between the experimental and calculated harmonic vibrational frequencies are less than 1.7 cm{sup −1}, and the discrepancies for the anharmonic correction are less than 0.1 cm{sup −1}. We show that correlation between atomic electronegativity differences and permanent dipole moment of heteronuclear alkali dimers is not perfect. To obtain the vibrational energies and wave functions the vibrational Schrödinger equation is solved with the B-spline basis set method. The transition dipole moments between all vibrational states, the Einstein coefficients, and the lifetimes of the vibrational states are calculated. We analyze the decay rates of the vibrational states in terms of spontaneous emission, and stimulated emission and absorption induced by black body radiation. In all studied heteronuclear alkali dimers the ground vibrational states have much longer lifetimes than any excited states.
Fedorov, Dmitry A; Derevianko, Andrei; Varganov, Sergey A
2014-05-14
We calculate the potential energy curves, the permanent dipole moment curves, and the lifetimes of the ground and excited vibrational states of the heteronuclear alkali dimers XY (X, Y = Li, Na, K, Rb, Cs) in the X(1)Σ(+) electronic state using the coupled cluster with singles doubles and triples method. All-electron quadruple-ζ basis sets with additional core functions are used for Li and Na, and small-core relativistic effective core potentials with quadruple-ζ quality basis sets are used for K, Rb, and Cs. The inclusion of the coupled cluster non-perturbative triple excitations is shown to be crucial for obtaining the accurate potential energy curves. A large one-electron basis set with additional core functions is needed for the accurate prediction of permanent dipole moments. The dissociation energies are overestimated by only 14 cm(-1) for LiNa and by no more than 114 cm(-1) for the other molecules. The discrepancies between the experimental and calculated harmonic vibrational frequencies are less than 1.7 cm(-1), and the discrepancies for the anharmonic correction are less than 0.1 cm(-1). We show that correlation between atomic electronegativity differences and permanent dipole moment of heteronuclear alkali dimers is not perfect. To obtain the vibrational energies and wave functions the vibrational Schrödinger equation is solved with the B-spline basis set method. The transition dipole moments between all vibrational states, the Einstein coefficients, and the lifetimes of the vibrational states are calculated. We analyze the decay rates of the vibrational states in terms of spontaneous emission, and stimulated emission and absorption induced by black body radiation. In all studied heteronuclear alkali dimers the ground vibrational states have much longer lifetimes than any excited states.
NASA Astrophysics Data System (ADS)
Ma, Yongbin; Zhang, Yahui; Kennedy, David
2015-09-01
Based on the concept of the hybrid finite element (FE) analysis and statistical energy analysis (SEA), a new hybrid method is developed for the mid-frequency vibration of a system comprising rectangular thin plates. The wave propagation method based on symplectic analysis is used to describe the vibration of the deterministic plate component. By enforcing the displacement continuity and equilibrium of force at the connection interface, the dynamic coupling between the deterministic plate component and the statistical plate component described by SEA is established. Furthermore, the hybrid solution formulation for the mid-frequency vibration of the system built up by plates is proposed. The symplectic analytical wave describing the deterministic plate component eliminates the boundary condition limitation of the traditional analytical wave propagation method and overcomes the numerical instability of numerical wave propagation methods. Numerical examples compare results from the proposed method with those from the hybrid FE-SEA method and the Monte Carlo method. The comparison illustrates that the proposed method gives good predictions for the mid-frequency behavior of the system considered here with low computational time. In addition, a constant proportionality coefficient between the system coupling power and the energy difference between the plate components can be found, when external forces are applied at different locations on a line perpendicular to the wave propagation direction. Based on this finding, two fast solution techniques are developed for the energy response of the system, and are validated by numerical examples.
Energy neutral and low power wireless communications
NASA Astrophysics Data System (ADS)
Orhan, Oner
Wireless sensor nodes are typically designed to have low cost and small size. These design objectives impose restrictions on the capacity and efficiency of the transceiver components and energy storage units that can be used. As a result, energy becomes a bottleneck and continuous operation of the sensor network requires frequent battery replacements, increasing the maintenance cost. Energy harvesting and energy efficient transceiver architectures are able to overcome these challenges by collecting energy from the environment and utilizing the energy in an intelligent manner. However, due to the nature of the ambient energy sources, the amount of useful energy that can be harvested is limited and unreliable. Consequently, optimal management of the harvested energy and design of low power transceivers pose new challenges for wireless network design and operation. The first part of this dissertation is on energy neutral wireless networking, where optimal transmission schemes under different system setups and objectives are investigated. First, throughput maximization for energy harvesting two-hop networks with decode-and-forward half-duplex relays is studied. For a system with two parallel relays, various combinations of the following four transmission modes are considered: Broadcast from the source, multi-access from the relays, and successive relaying phases I and II. Next, the energy cost of the processing circuitry as well as the transmission energy are taken into account for communication over a broadband fading channel powered by an energy harvesting transmitter. Under this setup, throughput maximization, energy maximization, and transmission completion time minimization problems are studied. Finally, source and channel coding for an energy-limited wireless sensor node is investigated under various energy constraints including energy harvesting, processing and sampling costs. For each objective, optimal transmission policies are formulated as the solutions of a
Energy storage options for space power
NASA Astrophysics Data System (ADS)
Hoffman, H. W.; Martin, J. F.; Olszewski, M.
Including energy storage in a space power supply enhances the feasibility of using thermal power cycles (Rankine or Brayton) and providing high-power pulses. Superconducting magnets, capacitors, electrochemical batteries, thermal phase-change materials (PCM), and flywheels are assessed; the results obtained suggest that flywheels and phase-change devices hold the most promise. Latent heat storage using inorganic salts and metallic eutectics offers thermal energy storage densities of 1500 kJ/kg to 2000 kJ/kg at temperatures to 1675 K. Innovative techniques allow these media to operate in direct contact with the heat engine working fluid. Enhancing thermal conductivity and/or modifying PCM crystallization habit provide other options. Flywheels of low-strain graphite and Kevlar fibers have achieved mechanical energy storage densities of 300 kJ/kg. With high-strain graphite fibers, storage densities appropriate to space power needs (about 500 kJ/kg) seem feasible. Coupling advanced flywheels with emerging high power density homopolar generators and compulsators could result in electric pulse-power storage modules of significantly higher energy density.
Power and Energy Architecture for Army Advanced Energy Initiative
2006-11-01
requirement for power and energy in a rapidly modernized, highly digital, and network -centric Army is growing exponentially. Simultaneously the ability to...concept will provide synergy to requirements, platforms, network architectures and technologies based upon visibility, direction and standardization...In short, we must move from a “stranded” energy architecture to a “ networked or grid” architecture. The Army needs to view battlefield energy
Energy transfer efficiency in the chromophore network strongly coupled to a vibrational mode
NASA Astrophysics Data System (ADS)
Mourokh, Lev G.; Nori, Franco
2015-11-01
Using methods from condensed matter and statistical physics, we examine the transport of excitons through the photosynthetic complex from a receiving antenna to a reaction center. Writing the equations of motion for the exciton creation-annihilation operators, we are able to describe the exciton dynamics, even in the regime when the reorganization energy is of the order of the intrasystem couplings. We determine the exciton transfer efficiency in the presence of a quenching field and protein environment. While the majority of the protein vibrational modes are treated as a heat bath, we address the situation when specific modes are strongly coupled to excitons and examine the effects of these modes on the energy transfer efficiency in the steady-state regime. Using the structural parameters of the Fenna-Matthews-Olson complex, we find that, for vibrational frequencies below 16 meV, the exciton transfer is drastically suppressed. We attribute this effect to the formation of a "mixed exciton-vibrational mode" where the exciton is transferred back and forth between the two pigments with the absorption or emission of vibrational quanta, instead of proceeding to the reaction center. The same effect suppresses the quantum beating at the vibrational frequency of 25 meV. We also show that the efficiency of the energy transfer can be enhanced when the vibrational mode strongly couples to the third pigment only, instead of coupling to the entire system.
Collisional vibrational energy transfer of OH (A 2Sigma + , v'=1)
NASA Astrophysics Data System (ADS)
Williams, Leah R.; Crosley, David R.
1996-05-01
Vibrational energy transfer (VET) and quenching of the v'=1 level of A 2Σ+ OH have been studied using laser-induced fluorescence in a discharge flow cell at room temperature. VET cross sections (Å2) are N2, 30.1±2.8; O2, 2.8±0.3; Ar, 0.56±0.05; H2O, 8.6±0.6. The rotational energy distribution in v'=0 following the VET event was determined for nine colliders. It is nonthermal, generally populating high rotational levels. There are three broad categories of colliders that cause varying degrees of vibrational to rotational energy transfer; H2, D2, and CH4 show the least; N2, CO2, CF4, and N2O more; and O2 and Ar the most, with about one-third of the vibrational energy appearing as OH rotation.
Do, T. P. T.; Lopes, M. C. A.; Konovalov, D. A.; White, R. D.; Brunger, M. J. E-mail: darryl.jones@flinders.edu.au; Jones, D. B. E-mail: darryl.jones@flinders.edu.au
2015-03-28
We report differential cross sections (DCSs) for electron-impact vibrational-excitation of tetrahydrofuran, at intermediate incident electron energies (15-50 eV) and over the 10°-90° scattered electron angular range. These measurements extend the available DCS data for vibrational excitation for this species, which have previously been obtained at lower incident electron energies (≤20 eV). Where possible, our data are compared to the earlier measurements in the overlapping energy ranges. Here, quite good agreement was generally observed where the measurements overlapped.
Vibration exercise as a warm-up modality for deadlift power output.
Cochrane, Darryl J; Coley, Karl W; Pritchard, Hayden J; Barnes, Matthew J
2015-04-01
Vibration exercise (VbX) has gained popularity as a warm-up modality to enhance performance in golf, baseball, and sprint cycling, but little is known about the efficacy of using VbX as a warm-up before resistance exercise, such as deadlifting. The aim of this study was to compare the effects of a deadlift (DL)-specific warm-up, VbX warm-up, and Control on DL power output (PO). The DL warm-up (DL-WU) included 10, 8, and 5 repetitions performed at 30, 40, and 50% 1-repetition maximum (1RM), respectively, where the number of repetitions was matched by body-weight squats performed with vibration and without vibration (Control). The warm-up conditions were randomized and performed at least 2 days apart. Peak power (PP), mean power, rate of force development (RFD), and electromyography (EMG) were measured during the concentric phase of 2 consecutive DLs (75% 1RM) at 30 seconds and 2:30 minutes after the warm-up conditions. There was no significant (p > 0.05) main effect or interaction effect between the DL-WU, VbX warm-up, and Control for PP, mean power, RFD, and EMG. Vibration exercise warm-up did not exhibit an ergogenic effect to potentiate muscle activity more than the specific DL-WU and Control. Therefore, DL PO is affected to a similar extent, irrespective of the type of stimuli, when the warm-up is not focused on raising muscle temperature.
A test rig for the measurement of vibration in hand-held power tools.
Hansson, J E; Kihlberg, S
1983-03-01
The purpose of the present project was to study the possibility of using a test rig for the measurement of vibration and noise from hand-held power tools. A test rig was designed to give the same effect on tool handle vibration as the human hand/arm system. Work was simulated by feeding the material to be processed against the tool, clamped into the rig, with the aid of a co-ordinate table. It was designed for use in studies of impact drills, chain saws, grinders and similar power tools. The report describes a proposal for testing the vibration properties of impact drills. Drilling with the test rig was compared with manual drilling. The difference in the acceleration level between the two methods was about 1 dB for ISO-weighted values in the critical direction. Both methods showed good reproducibility. The possibility of conducting noise level tests of a power tool in the rig was studied and the results are reported separately.
Energy Finite Element Analysis Developments for Vibration Analysis of Composite Aircraft Structures
NASA Technical Reports Server (NTRS)
Vlahopoulos, Nickolas; Schiller, Noah H.
2011-01-01
The Energy Finite Element Analysis (EFEA) has been utilized successfully for modeling complex structural-acoustic systems with isotropic structural material properties. In this paper, a formulation for modeling structures made out of composite materials is presented. An approach based on spectral finite element analysis is utilized first for developing the equivalent material properties for the composite material. These equivalent properties are employed in the EFEA governing differential equations for representing the composite materials and deriving the element level matrices. The power transmission characteristics at connections between members made out of non-isotropic composite material are considered for deriving suitable power transmission coefficients at junctions of interconnected members. These coefficients are utilized for computing the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations is solved numerically and the vibration levels within the entire system can be computed. The new EFEA formulation for modeling composite laminate structures is validated through comparison to test data collected from a representative composite aircraft fuselage that is made out of a composite outer shell and composite frames and stiffeners. NASA Langley constructed the composite cylinder and conducted the test measurements utilized in this work.
Energy flow for electric power system deregulation
NASA Astrophysics Data System (ADS)
Lin, Chia-Hung
Over the past few years, the electric power utility industry in North America and other countries has experienced a strong drive towards deregulation. People have considered the necessity of deregulation of electric utilities for higher energy efficiency and energy saving. The vertically integrated monopolistic industry is being transferred into a horizontally integrated competitive structure in some countries. Wheeling charges are a current high priority problem throughout the power industry, for independent power producers, as well as regulators. Nevertheless the present transmission pricing mechanism fails to be adjusted by a customer loading condition. Customer loading is dynamic, but the present wheeling charge method is fixed, not real-time. A real-time wheeling charge method is developed in this dissertation. This dissertation introduces a concept of a power flow network which can be used for the calculation of power contribution factors in a network. The contribution factor is defined as the ratio of the power contributed by a particular source to a line flow or bus load to the total output of the source. Generation, transmission, and distribution companies can employ contribution factors for the calculation of energy cost, wheeling charges, and loss compensation. Based on the concept of contribution factors, a proposed loss allocation method is developed in this dissertation. Besides, counterflow condition will be given a credit in the proposed loss allocation method. A simple 22-bus example was used for evaluating the contribution factors, proposed wheeling charge method, and loss allocation method.
Origin of low-energy quadrupole collectivity in vibrational nuclei.
Walz, C; Fujita, H; Krugmann, A; von Neumann-Cosel, P; Pietralla, N; Ponomarev, V Yu; Scheikh-Obeid, A; Wambach, J
2011-02-11
The coupling of the giant quadrupole resonance to valence-space configurations is shown to be the origin of the formation of low-lying quadrupole-collective structures in vibrational nuclei with symmetric and mixed-symmetric character with respect to the proton-neutron degree of freedom. For the first time experimental evidence for this picture is obtained from electron- and proton scattering experiments on the nucleus ^{92}Zr that are sensitive to the relative phase of valence-space amplitudes by quantum interference.
Two-dimensional concentrated-stress low-frequency piezoelectric vibration energy harvesters
Sharpes, Nathan; Abdelkefi, Abdessattar; Priya, Shashank
2015-08-31
Vibration-based energy harvesters using piezoelectric materials have long made use of the cantilever beam structure. Surmounting the deficiencies in one-dimensional cantilever-based energy harvesters has been a major focus in the literature. In this work, we demonstrate a strategy of using two-dimensional beam shapes to harvest energy from low frequency excitations. A characteristic Zigzag-shaped beam is created to compare against the two proposed two-dimensional beam shapes, all of which occupy a 25.4 × 25.4 mm{sup 2} area. In addition to maintaining the low-resonance bending frequency, the proposed beam shapes are designed with the goal of realizing a concentrated stress structure, whereby stress in the beam is concentrated in a single area where a piezoelectric layer may be placed, rather than being distributed throughout the beam. It is shown analytically, numerically, and experimentally that one of the proposed harvesters is able to provide significant increase in power production, when the base acceleration is set equal to 0.1 g, with only a minimal change in the resonant frequency compared to the current state-of-the-art Zigzag shape. This is accomplished by eliminating torsional effects, producing a more pure bending motion that is necessary for high electromechanical coupling. In addition, the proposed harvesters have a large effective beam tip whereby large tip mass may be placed while retaining a low-profile, resulting in a low volume harvester and subsequently large power density.
NASA Astrophysics Data System (ADS)
Mitsuya, H.; Ashizawa, H.; Ishibashi, K.; Homma, H.; Ataka, M.; Hashiguchi, G.; Fujita, H.; Toshiyoshi, H.
2016-11-01
An energy harvester has been developed to efficiently earn energy from both cyclic and impulse vibrations by using a symmetric pair of comb-electrodes that are heavily doped with potassium-ions to form electrets. By equalizing the electromechanical forces on the opposing comb-drives, energy conversion efficiency is enhanced for both impulses and broad-frequency harmonic vibrations.
Vibrational energy flow models for the Rayleigh-Love and Rayleigh-Bishop rods
NASA Astrophysics Data System (ADS)
Han, Ju-Bum; Hong, Suk-Yoon; Song, Jee-Hun; Kwon, Hyun-Wung
2014-01-01
Energy Flow Analysis (EFA) has been developed to predict the vibrational energy density of the system structures in the medium-to-high frequency range. The elementary longitudinal wave theory is often used to describe the longitudinal vibration of a slender rod. However, for relatively large diameter rods or high frequency ranges, the elementary longitudinal wave theory is inaccurate because the lateral motions are not taken into account. In this paper, vibrational energy flow models are developed to analyze the longitudinally vibrating Rayleigh-Love rod considering the effect of lateral inertia, and the Rayleigh-Bishop rod considering the effect not only of the lateral inertia but also of the shear stiffness. The derived energy governing equations are second-order differential equations which predict the time and space averaged energy density and active intensity distributions in a rod. To verify the accuracy of the developed energy flow models, various numerical analyses are performed for a rod and coupled rods. Also, the EFA results for the Rayleigh-Love and Rayleigh-Bishop rods are compared with the analytical solutions for these models, the traditional energy flow solutions, and the analytical solutions for the classical rod.
NASA Astrophysics Data System (ADS)
Pollak, Eli
1981-05-01
A necessary and sufficient condition for the existence of a classical vibrationally adiabatic barrier or well in collinear systems is the existence of periodic orbit dividing surfaces. Knowledge of all pods immediately provides all adiabatic barriers and wells. Furthermore, the classical equation connecting the barriers and wells to the masses and potential energy surface of the system is shown, under mild conditions, to be identical in form to the corresponding quantal equation. The only difference is in the determination of the vibrational state which is obtained by WKB quantization classically. The classical barriers and wells can therefore be used to analyze quantal computations. Such analysis is provided for the hydrogen exchange reaction and the F+HH system. A novel result is the existence of vibrationally adiabatic barriers even where no saddle point exists on the static potential energy surface. These barriers are an outcome of competition between the increase of potential energy and decrease of vibrational force constant along the reaction coordinate. Their existence is therefore of general nature — not limited to the specific structure of a given potential energy surface. The experimental significance of these barriers is discussed. The implications on the use of forward or reverse quasiclassical computations is analyzed. A definite conclusion is that one should not average over initial vibrational action in such calculations.
Trajectory studies of vibrational energy transfer in gas--surface collisions
Lucchese, R.R.; Tully, J.C.
1984-04-01
We have applied the stochastic trajectory method to the scattering of NO from the (001) surface of an LiF crystal. The surface was represented by a 32 atom primary zone and the effects of the rest of the surface atoms were included using the Generalized Langevin Equation method. The forces between the surface atoms were treated using a shell model and the gas--surface interactions included short-range repulsions, attractive dispersion forces, and the interaction of the dipole moment of NO and the surface ions. The dependence of the dipole moment and the dependence of the molecular polarizability on the internuclear separation of NO were also included. The calculated vibrational energy accommodation coefficient was less than 1% when trapping of the gas diatom was negligible. By modifying the vibrational frequency of the scattered diatom we have examined the dependence of vibrational energy transfer on frequency. An exponential dependence on the ratio of the molecular frequency to the surface Debye frequency was found, similar to behavior observed for vibrational relaxation in condensed phases. We have also examined the relative efficiency of the coupling of the vibrational mode to the translational and rotational modes of the gas diatom and to the phonon modes of the surface. We found that the vibrational mode is most strongly coupled to the surface phonons with a much weaker coupling to the rotational and translational modes.
Lan, C. B.; Qin, W. Y.
2014-09-15
This letter investigates the energy harvesting from the horizontal coherent resonance of a vertical cantilever beam subjected to the vertical base excitation. The potential energy of the system has two symmetric potential wells. So, under vertical excitation, the system can jump between two potential wells, which will lead to the large vibration in horizontal direction. Two piezoelectric patches are pasted to harvest the energy. From experiment, it is found that the vertical excitation can make the beam turn to be bistable. The system can transform vertical vibration into horizontal vibration of low frequency when excited by harmonic motion. The horizontal coherence resonance can be observed when excited by a vertical white noise. The corresponding output voltages of piezoelectric films reach high values.
Effect of collision energy and vibrational excitation on endothermic ion-molecule reactions
Turner, T.P.
1984-07-01
This thesis is divided into two major parts. In the first part an experimental study of proton and deuteron transfer in H/sub 2//sup +/ + He and HD/sup +/ + He has been carried out as a function of kinetic and vibrational energy. The data gives evidence that at lower kinetic energies, the spectator stripping mechanism indeed plays an important role when H/sub 2//sup +/ or HD/sup +/ is vibrationally excited. The second half of this thesis examines the relative efficiencies between the excitation of C-C stretching vibration and collision energy on the promotion of the H atom transfer reaction of C/sub 2/H/sub 2//sup +/ + H/sub 2/ ..-->.. C/sub 2/H/sub 3//sup +/ + H.
A method for analyzing the vibrational energy flow in biomolecules in solution.
Soler, Miguel Angel; Bastida, Adolfo; Farag, Marwa H; Zúñiga, José; Requena, Alberto
2011-11-28
A method is proposed to analyze the intra- and intermolecular vibrational energy flow occurring in biomolecules in solution during relaxation processes. It is based on the assumption that the total energy exchanged between the vibrational modes is minimal and the global process is essentially statistical. This statistical minimum flow method is shown to provide very useful information about the amount and the rate at which energy is transferred between the individual vibrations of the molecule. To demonstrate the performance of the method, an application is made to the relaxation of the amide I mode of N-methylacetamide-d in aqueous D(2)O solution which yields a detailed quantitative description of the process.
Abramavicius, Darius; Valkunas, Leonas
2016-01-01
Oscillatory features of two-dimensional spectra of photosynthetic pigment-protein complexes during few picoseconds after electronic excitations of chlorophylls in various pigment-proteins were recently related to the coherent nuclear vibrations. It has been also speculated that the vibrations may assist the excitonic energy transfer and charge separation, hence contributing to energy transport and energy conversion efficiency. Here, we consider three theoretical approaches usually used for characterization of the excitation dynamics and charge separation, namely Redfield, Förster, and Marcus model descriptions, regarding this question. We show that two out of the three mechanisms require explicit resonances of excitonic splittings and the nuclear vibration frequencies. However, the third one related to the electron transfer is in principle off resonant.
Intermediate energy electron impact excitation of composite vibrational modes in phenol.
Neves, R F C; Jones, D B; Lopes, M C A; Nixon, K L; de Oliveira, E M; da Costa, R F; Varella, M T do N; Bettega, M H F; Lima, M A P; da Silva, G B; Brunger, M J
2015-05-21
We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C6H5OH). The measurements were carried out at incident electron energies in the range 15-40 eV and for scattered-electron angles in the range 10-90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C6H5OH molecule by electron impact.
Comparison of Five Topologies of Cantilever-based MEMS Piezoelectric Vibration Energy Harvesters
NASA Astrophysics Data System (ADS)
Jia, Y.; Seshia, A. A.
2014-11-01
In the realm of MEMS piezoelectric vibration energy harvesters, cantilever-based designs are by far the most popular. Despite being deceptively simple, the active piezoelectric area near the clamped end is able to accumulate maximum strain-generated-electrical-charge, while the free end is able to accommodate a proof mass without compromising the effective area of the piezoelectric generator since it experiences minimal strain anyway. While other contending designs do exist, this paper investigates five micro-cantilever (MC) topologies, namely: a plain MC, a tapered MC, a lined MC, a holed MC and a coupled MC, in order to assess their relative performance as an energy harvester. Although a classical straight and plain MC offers the largest active piezoelectric area, alternative MC designs can potentially offer higher average mechanical strain distribution for a given mechanical loading. Numerical simulation and experimental comparison of these 5 MCs (0.5 μ AlN on 10 μm Si) with the same practical dimensions of 500 μm and 2000 μm, suggest a cantilever with a coupled subsidiary cantilever yield the best power performance, closely followed by the classical plain topology.
NASA Astrophysics Data System (ADS)
Blažević, D.; Zelenika, S.
2015-05-01
Scavenging of low-level ambient vibrations i.e. the conversion of kinetic into electric energy, is proven as effective means of powering low consumption electronic devices such as wireless sensor nodes. Cantilever based scavengers are characterised by several advantages and thus thoroughly investigated; analytical models based on a distributed parameter approach, Euler-Bernoulli beam theory and eigenvalue analysis have thus been developed and experimentally verified. Finite element models (FEM) have also been proposed employing different modelling approaches and commercial software packages with coupled analysis capabilities. An approach of using a FEM analysis of a piezoelectric cantilever bimorph under harmonic excitation is used in this work. Modal, harmonic and linear and nonlinear transient analyses are performed. Different complex dynamic effects are observed and compared to the results obtained by using a distributed parameter model. The influence of two types of finite elements and three mesh densities is also investigated. A complex bimorph cantilever, based on commercially available Midé Technology® Volture energy scavengers, is then considered. These scavengers are characterised by an intricate multilayer structure not investigated so far in literature. An experimental set-up is developed to evaluate the behaviour of the considered class of devices. The results of the modal and the harmonic FEM analyses of the behaviour of the multilayer scavengers are verified experimentally for three different tip masses and 12 different electrical load values. A satisfying agreement between numerical and experimental results is achieved.
Analysis of vibrational-translational energy transfer using the direct simulation Monte Carlo method
NASA Technical Reports Server (NTRS)
Boyd, Iain D.
1991-01-01
A new model is proposed for energy transfer between the vibrational and translational modes for use in the direct simulation Monte Carlo method (DSMC). The model modifies the Landau-Teller theory for a harmonic oscillator and the rate transition is related to an experimental correlation for the vibrational relaxation time. Assessment of the model is made with respect to three different computations: relaxation in a heat bath, a one-dimensional shock wave, and hypersonic flow over a two-dimensional wedge. These studies verify that the model achieves detailed balance, and excellent agreement with experimental data is obtained in the shock wave calculation. The wedge flow computation reveals that the usual phenomenological method for simulating vibrational nonequilibrium in the DSMC technique predicts much higher vibrational temperatures in the wake region.
Aspects of the Eckart frame ro-vibrational kinetic energy operator
NASA Astrophysics Data System (ADS)
Szalay, Viktor
2015-08-01
A most decisive part of developing the Eckart frame ro-vibrational kinetic energy operator (KEO) in terms of curvilinear internal coordinates is the introduction of vibrational displacements obeying the Eckart conditions. It is examined here, how such displacements may be constructed by orthogonal and nonorthogonal transformations, and how they can be employed in developing the KEO. In particular, it is shown analytically, by term by term comparison, that the Eckart KEOs obtained by employing Pickett's method and the gateway Hamiltonian method are equivalent. That is, although it may appear in the form of very different expressions, the general, exact ro-vibrational Eckart frame KEO is unique. As side result, it has been shown that the simple formula of the pseudo-potential derived by Watson for the exact KEO given in normal coordinates applies to any Eckart frame KEO, irrespective of the choice of the vibrational coordinates.
Novel Nuclear Powered Photocatalytic Energy Conversion
White,John R.; Kinsmen,Douglas; Regan,Thomas M.; Bobek,Leo M.
2005-08-29
The University of Massachusetts Lowell Radiation Laboratory (UMLRL) is involved in a comprehensive project to investigate a unique radiation sensing and energy conversion technology with applications for in-situ monitoring of spent nuclear fuel (SNF) during cask transport and storage. The technology makes use of the gamma photons emitted from the SNF as an inherent power source for driving a GPS-class transceiver that has the ability to verify the position and contents of the SNF cask. The power conversion process, which converts the gamma photon energy into electrical power, is based on a variation of the successful dye-sensitized solar cell (DSSC) design developed by Konarka Technologies, Inc. (KTI). In particular, the focus of the current research is to make direct use of the high-energy gamma photons emitted from SNF, coupled with a scintillator material to convert some of the incident gamma photons into photons having wavelengths within the visible region of the electromagnetic spectrum. The high-energy gammas from the SNF will generate some power directly via Compton scattering and the photoelectric effect, and the generated visible photons output from the scintillator material can also be converted to electrical power in a manner similar to that of a standard solar cell. Upon successful implementation of an energy conversion device based on this new gammavoltaic principle, this inherent power source could then be utilized within SNF storage casks to drive a tamper-proof, low-power, electronic detection/security monitoring system for the spent fuel. The current project has addressed several aspects associated with this new energy conversion concept, including the development of a base conceptual design for an inherent gamma-induced power conversion unit for SNF monitoring, the characterization of the radiation environment that can be expected within a typical SNF storage system, the initial evaluation of Konarka's base solar cell design, the design and
NASA Astrophysics Data System (ADS)
Nawayseh, Naser; Griffin, Michael J.
2012-01-01
Although the discomfort or injury associated with whole-body vibration cannot be predicted directly from the power absorbed during exposure to vibration, the absorbed power may contribute to understanding of the biodynamics involved in such responses. From measurements of force and acceleration at the seat, the feet, and the backrest, the power absorbed at these three locations was calculated for subjects sitting in four postures (feet hanging, maximum thigh contact, average thigh contact, and minimum thigh contact) both with and without a rigid vertical backrest while exposed to four magnitudes (0.125, 0.25, 0.625, and 1.25 m s -2 rms) of random fore-and-aft vibration. The power absorbed by the body at the supporting seat surface when there was no backrest showed a peak around 1 Hz and another peak between 3 and 4 Hz. Supporting the back with the backrest decreased the power absorbed at the seat at low frequencies but increased the power absorbed at high frequencies. Foot support influenced both the magnitude and the frequency of the peaks in the absorbed power spectra as well as the total absorbed power. The measurements of absorbed power are consistent with backrests being beneficial during exposure to low frequency fore-and-aft vibration but detrimental with high frequency fore-and-aft vibration.
Financing renewable energy for Village Power application
Santibanez-Yeneza, G.
1997-12-01
When one talks of rural development, no doubt, the issue of rural energy is not far behind. As a significant component of any development strategy, rural energy is seen as the engine for growth that can bring about economic upliftment in the countryside. Many approaches to rural energy development have been tried. These approaches differ from country to country. But regardless of structure and approach, the goal remain essentially the same: to provide rural communities access to reliable energy services at affordable prices. In recent years, as global concern for the environment has increased, many governments have turned to renewable energy as a more environment friendly alternative to rural electrification. Technological advances in renewable energy application has helped to encourage this use. System reliability has improved, development costs have, to some extent been brought down and varied application approaches have been tried and tested in many areas. Indeed, there is huge potential for the development of renewable energy in the rural areas of most developing countries. At the rural level, renewable energy resources are almost always abundantly available: woodwaste, agricultural residues, animal waste, small-scale hydro, wind, solar and even sometimes geothermal resources. Since smaller scale systems are usually expected in these areas, renewable energy technologies can very well serve as decentralized energy systems for rural application. And not only for rural applications, new expansion planning paradigms have likewise led to the emergence of decentralized energy systems not only as supply options but also as corrective measures for maintaining end of line voltage levels. On the other hand, where renewable energy resource can provide significant blocks of power, they can be relied upon to provide indigenous power to the grids.
NASA Astrophysics Data System (ADS)
Simpkins, Blake S.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Spann, Bryan T.; Owrutsky, Jeffrey C.
2016-09-01
Coherent coupling between an optical transition and confined optical mode have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we demonstrate both static and dynamic results for vibrational bands strongly coupled to optical cavities. We experimentally and numerically describe strong coupling between a Fabry-Pérot cavity and carbonyl stretch ( 1730 cm 1) in poly-methylmethacrylate and provide evidence that the mixed-states are immune to inhomogeneous broadening. We investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of a urethane monomer. Rabi splittings are in excellent agreement with an analytical description using no fitting parameters. Ultrafast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band, as well as drastically modified relaxation rates. We speculate these modified kinetics are a consequence of the energy proximity between the vibration-cavity polariton modes and excited state transitions and that polaritons offer an alternative relaxation path for vibrational excitations. Varying the polariton energies by angle-tuning yields transient results consistent with this hypothesis. Furthermore, Rabi oscillations, or quantum beats, are observed at early times and we see evidence that these coherent vibration-cavity polariton excitations impact excited state population through cavity losses. Together, these results indicate that cavity coupling may be used to influence both excitation and relaxation rates of vibrations. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied in steady state and dynamically.
NASA Astrophysics Data System (ADS)
Yang, Yangyiwei; Wang, Shuai; Stein, Peter; Xu, Bai-Xiang; Yang, Tongqing
2017-04-01
Due to many potential promising applications, vibration-based piezoelectric energy harvesters (VPEH) with a clamped circular diaphragm are an intensively studied design in the field of piezoelectric energy harvesters. Nonetheless, their performance still leaves space for improvement, which is the primary target of this article. We define two structural parameters, namely the ratio ϖ 1 between the bonding area and the piezoceramic diameter as well as the ratio ϖ 2 between the clamping rim and the substrate diameter, to characterize these structures. A vibration model is developed in order to provide an analytical foundation for the identification of optimal parameters ϖ 1 and ϖ 2. It is verified by finite-element simulations and substantive experiments. The results allow to relate the device performance, including resonance frequency and output power, to ϖ 1 and ϖ 2. This shows that the output rises with increasing ϖ 2, and that the maximum output for a given ϖ 2 always lies in the range {\\varpi }1\\in ({0.1,} 0.2). Based on this observation, an improved harvester structure with a pre-stress of 0.3 N is identified, that exhibits a matched power up to 16.3 mW at 219 Hz. This demonstrates the feasibility to achieve VPEHs with higher outputs and lower eigenfrequency through simultaneous modification of ϖ 1 and ϖ 2, which is highly beneficial for low-frequency energy harvesting.
NASA Astrophysics Data System (ADS)
Ferin, G.; Bantignies, C.; Le Khanh, H.; Flesch, E.; Nguyen-Dinh, A.
2015-12-01
Harvesting energy from ambient mechanical vibrations is a smart and efficient way to power autonomous sensors and support innovative developments in IoT (Internet of Things), WSN (Wireless Sensor Network) and even implantable medical devices. Beyond the environmental operating conditions, efficiency of such devices is mainly related to energy source properties like the amplitude of vibrations and its spectral contain and some of these applications exhibit a quite low frequency spectrum where harvesting surrounding mechanical energy make sense, typically 5-50Hz for implantable medical devices or 50Hz-150Hz for industrial machines. Harvesting such low frequency vibrations is a challenge since it leads to adapt the resonator geometries to the targeted frequency or to use out-off band indirect harvesting strategies. In this paper we present a piezoelectric based vibrational energy harvesting device (PEH) which could be integrated into a biocompatible package to power implantable sensor or therapeutic medical devices. The presented architecture is a serial bimorph laminated with ultra-thinned (ranging from 15μm to 100μm) outer PZT “skins” that could operate at a “very low frequency”, below 25Hz typically. The core process flow is disclosed and performances highlighted with regards to other low frequency demonstrations.
Utilising Nonlinear Air Damping as a Soft Mechanical Stopper for MEMS Vibration Energy Harvesting
NASA Astrophysics Data System (ADS)
Chen, Shao-Tuan; Du, Sijun; Arroyo, Emmanuelle; Jia, Yu; Seshia, Ashwin
2016-11-01
This paper reports on the theory and experimental verification of utilising air damping as a soft stopper mechanism for piezoelectric vibration energy harvesting to enhance shock resistance. Experiments to characterise device responsiveness under various vibration conditions were performed at different air pressure levels, and a dimensionless model was constructed with nonlinear damping terms included to model PVEH response. The relationship between the quadratic damping coefficient ζ n and air pressure is empirically established, and an optimal pressure level is calculated to trade off harvestable energy and device robustness for specific environmental conditions.
Second-order many-body perturbation expansions of vibrational Dyson self-energies.
Hermes, Matthew R; Hirata, So
2013-07-21
Second-order many-body perturbation theories for anharmonic vibrational frequencies and zero-point energies of molecules are formulated, implemented, and tested. They solve the vibrational Dyson equation self-consistently by taking into account the frequency dependence of the Dyson self-energy in the diagonal approximation, which is expanded in a diagrammatic perturbation series up to second order. Three reference wave functions, all of which are diagrammatically size consistent, are considered: the harmonic approximation and diagrammatic vibrational self-consistent field (XVSCF) methods with and without the first-order Dyson geometry correction, i.e., XVSCF[n] and XVSCF(n), where n refers to the truncation rank of the Taylor-series potential energy surface. The corresponding second-order perturbation theories, XVH2(n), XVMP2[n], and XVMP2(n), are shown to be rigorously diagrammatically size consistent for both total energies and transition frequencies, yield accurate results (typically within a few cm(-1) at n = 4 for water and formaldehyde) for both quantities even in the presence of Fermi resonance, and have access to fundamentals, overtones, and combinations as well as their relative intensities as residues of the vibrational Green's functions. They are implemented into simple algorithms that require only force constants and frequencies of the reference methods (with no basis sets, quadrature, or matrix diagonalization at any stage of the calculation). The rules for enumerating and algebraically interpreting energy and self-energy diagrams are elucidated in detail.
Tower Power: Producing Fuels from Solar Energy
ERIC Educational Resources Information Center
Antal, M. J., Jr.
1976-01-01
This article examines the use of power tower technologies for the production of synthetic fuels. This process overcomes the limitations of other processes by using a solar furnace to drive endothermic fuel producing reactions and the resulting fuels serve as a medium for storing solar energy. (BT)
Low-energy vibrational dynamics of cesium borate glasses.
Crupi, C; D'Angelo, G; Vasi, C
2012-06-07
Low-temperature specific heat and inelastic light scattering experiments have been performed on a series of cesium borate glasses and on a cesium borate crystal. Raman measurements on the crystalline sample have revealed the existence of cesium rattling modes in the same frequency region where glasses exhibit the boson peak (BP). These localized modes are supposed to overlap with the BP in cesium borate glasses affecting its magnitude. Their influence on the low frequency vibrational dynamics in glassy samples has been considered, and their contribution to the specific heat has been estimated. Evidence for a relation between the changes of the BP induced by the increased amount of metallic oxide and the variations of the elastic medium has been provided.
Multi-source energy harvester power management
NASA Astrophysics Data System (ADS)
Schlichting, Alexander D.; Tiwari, Rashi; Garcia, Ephrahim
2011-03-01
Much of the work on improving energy harvesting systems currently focuses on tasks beyond geometric optimization and has shifted to using complex feedback control circuitry. While the specific technique and effectiveness of the circuits have varied, an important goal is still out of reach for many desired applications: to produce sufficient and sustained power. This is due in part to the power requirements of the control circuits themselves. One method for increasing the robustness and versatility of energy harvesting systems which has started to receive some attention would be to utilize multiple energy sources simultaneously. If some or all of the present energy sources were harvested, the amount of constant power which could be provided to the system electronics would increase dramatically. This work examines two passive circuit topologies, parallel and series, for combining multiple piezoelectric energy harvesters onto a single storage capacitor using an LTspice simulation. The issue of the relative phase between the two piezoelectric signals is explored to show that the advantages of both configurations are significantly affected by increased relative phase values.
Yuksek, N. S.; Almasri, M.; Feng, Z. C.
2014-09-15
In this paper, we propose an electromagnetic power harvester that uses a transformative multi-impact approach to achieve a wide bandwidth response from low frequency vibration sources through frequency-up conversion. The device consists of a pick-up coil, fixed at the free edge of a cantilever beam with high resonant frequency, and two cantilever beams with low excitation frequencies, each with an impact mass attached at its free edge. One of the two cantilevers is designed to resonate at 25 Hz, while the other resonates at 50 Hz within the range of ambient vibration frequency. When the device is subjected to a low frequency vibration, the two low-frequency cantilevers responded by vibrating at low frequencies, and thus their thick metallic masses made impacts with the high resonance frequency cantilever repeatedly at two locations. This has caused it along with the pick-up coil to oscillate, relative to the permanent magnet, with decaying amplitude at its resonance frequency, and results in a wide bandwidth response from 10 to 63 Hz at 2 g. A wide bandwidth response between 10–51 Hz and 10–58 Hz at acceleration values of 0.5 g and 2 g, respectively, were achieved by adjusting the impact cantilever frequencies closer to each other (25 Hz and 45 Hz). A maximum output power of 85 μW was achieved at 5 g at 30 Hz across a load resistor, 2.68 Ω.
Vibrational energy harvesting by exploring structural benefits and nonlinear characteristics
NASA Astrophysics Data System (ADS)
Wei, Chongfeng; Jing, Xingjian
2017-07-01
Traditional energy harvesters are often of low efficiency due to very limited energy harvesting bandwidth, which should also be enough close to the ambient excitation frequency. To overcome this difficulty, some attempts can be seen in the literature typically with the purposes of either increasing the energy harvesting bandwidth with a harvester array, or enhancing the energy harvesting bandwidth and peak with nonlinear coupling effect etc. This paper presents an alternative way which can achieve tuneable resonant frequency (from high frequency to ultralow frequency) and improved energy harvesting bandwidth and peak simultaneously by employing special structural benefits and advantageous displacement-dependent nonlinear damping property. The proposed energy harvesting system employs a lever systems combined with an X-shape supporting structure and demonstrates very adjustable stiffness and unique nonlinear damping characteristics which are very beneficial for energy harvesting. It is shown that the energy harvesting performance of the proposed system is directly determined by several easy-to-tune structural parameters and also by the relative displacement in a special nonlinear manner, which provides a great flexibility and/or a unique tool for tuning and improving energy harvesting efficiency via matching excitation frequencies and covering a broader frequency band. This study potentially provides a new insight into the design of energy harvesting systems by employing structural benefits and geometrical nonlinearities.
Voltage scheduling for low power/energy
NASA Astrophysics Data System (ADS)
Manzak, Ali
2001-07-01
Power considerations have become an increasingly dominant factor in the design of both portable and desk-top systems. An effective way to reduce power consumption is to lower the supply voltage since voltage is quadratically related to power. This dissertation considers the problem of lowering the supply voltage at (i) the system level and at (ii) the behavioral level. At the system level, the voltage of the variable voltage processor is dynamically changed with the work load. Processors with limited sized buffers as well as those with very large buffers are considered. Given the task arrival times, deadline times, execution times, periods and switching activities, task scheduling algorithms that minimize energy or peak power are developed for the processors equipped with very large buffers. A relation between the operating voltages of the tasks for minimum energy/power is determined using the Lagrange multiplier method, and an iterative algorithm that utilizes this relation is developed. Experimental results show that the voltage assignment obtained by the proposed algorithm is very close (0.1% error) to that of the optimal energy assignment and the optimal peak power (1% error) assignment. Next, on-line and off-fine minimum energy task scheduling algorithms are developed for processors with limited sized buffers. These algorithms have polynomial time complexity and present optimal (off-line) and close-to-optimal (on-line) solutions. A procedure to calculate the minimum buffer size given information about the size of the task (maximum, minimum), execution time (best case, worst case) and deadlines is also presented. At the behavioral level, resources operating at multiple voltages are used to minimize power while maintaining the throughput. Such a scheme has the advantage of allowing modules on the critical paths to be assigned to the highest voltage levels (thus meeting the required timing constraints) while allowing modules on non-critical paths to be assigned
Sun, Kyung Ho; Kim, Young-Cheol; Kim, Jae Eun
2014-10-15
While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm{sup 3}, which was designed for a target frequency of as low as 100 Hz.
NASA Astrophysics Data System (ADS)
Sun, Kyung Ho; Kim, Young-Cheol; Kim, Jae Eun
2014-10-01
While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm3, which was designed for a target frequency of as low as 100 Hz.
NASA Astrophysics Data System (ADS)
Sekiguchi, K.; Shimojima, A.; Kajimoto, O.
2002-04-01
A pump-probe experiment was performed to examine vibrational population relaxation of diiodomethane (CH 2I 2) molecule dissolved in supercritical CO 2. Using an apparatus with femtosecond time resolution, we observed the contributions of intramolecular vibrational energy redistribution (IVR) and intermolecular vibrational energy transfer (VET) separately. IVR and VET rates were measured with varying solvent densities at a constant temperature. It is shown that the IVR rate is not density dependent while the VET rate increases with increasing density from 0.4 to 0.8 g cm-3. This observation suggests that the rate of the VET process is determined by solute-solvent collisions whereas the IVR rate is not much affected by solute-solvent interaction.
Dhote, Sharvari Zu, Jean; Zhu, Yang
2015-04-20
In this paper, a nonlinear wideband multi-mode piezoelectric vibration-based energy harvester (PVEH) is proposed based on a compliant orthoplanar spring (COPS), which has an advantage of providing multiple vibration modes at relatively low frequencies. The PVEH is made of a tri-leg COPS flexible structure, where three fixed-guided beams are capable of generating strong nonlinear oscillations under certain base excitation. A prototype harvester was fabricated and investigated through both finite-element analysis and experiments. The frequency response shows multiple resonance which corresponds to a hardening type of nonlinear resonance. By adding masses at different locations on the COPS structure, the first three vibration modes are brought close to each other, where the three hardening nonlinear resonances provide a wide bandwidth for the PVEH. The proposed PVEH has enhanced performance of the energy harvester in terms of a wide frequency bandwidth and a high-voltage output under base excitations.
Surowiec, Rachel K; Wang, Henry; Nagelkirk, Paul R; Frame, Jeffrey W; Dickin, D Clark
2014-07-01
Recently, individualized frequency (I-Freq) has been introduced with the notion that athletes may elicit a greater reflex response at differing levels (Hz) of vibration. The aim of the study was to evaluate acute whole-body vibration as a feasible intervention to increase power in trained cyclists and evaluate the efficacy of using I-Freq as an alternative to 30Hz, a common frequency seen in the literature. Twelve highly trained, competitive male cyclists (age, 29.9 ± 10.0 years; body height, 175.4 ± 7.8 cm; body mass, 77.3 ± 13.9 kg) participated in the study. A Wingate test for anaerobic power was administered on 3 occasions: following a control of no vibration, 30 Hz, or I-freq. Measures of peak power, average power (AP), and the rate of fatigue were recorded and compared with the vibration conditions using separate repeated measures analysis of variance. Peak power, AP, and the rate of fatigue were not significantly impacted by either the 30 Hz or I-Freq vibration interventions (p > 0.05). Given the trained status of the individuals in this study, the ability to elicit an acute response may have been muted. Future studies should further refine the vibration parameters used and assess changes in untrained or recreationally trained populations.
Distributed Wireless Power Transfer With Energy Feedback
NASA Astrophysics Data System (ADS)
Lee, Seunghyun; Zhang, Rui
2017-04-01
Energy beamforming (EB) is a key technique for achieving efficient radio-frequency (RF) transmission enabled wireless energy transfer (WET). By optimally designing the waveforms from multiple energy transmitters (ETs) over the wireless channels, they can be constructively combined at the energy receiver (ER) to achieve an EB gain that scales with the number of ETs. However, the optimal design of EB waveforms requires accurate channel state information (CSI) at the ETs, which is challenging to obtain practically, especially in a distributed system with ETs at separate locations. In this paper, we study practical and efficient channel training methods to achieve optimal EB in a distributed WET system. We propose two protocols with and without centralized coordination, respectively, where distributed ETs either sequentially or in parallel adapt their transmit phases based on a low-complexity energy feedback from the ER. The energy feedback only depends on the received power level at the ER, where each feedback indicates one particular transmit phase that results in the maximum harvested power over a set of previously used phases. Simulation results show that the two proposed training protocols converge very fast in practical WET systems even with a large number of distributed ETs, while the protocol with sequential ET phase adaptation is also analytically shown to converge to the optimal EB design with perfect CSI by increasing the training time. Numerical results are also provided to evaluate the performance of the proposed distributed EB and training designs as compared to other benchmark schemes.
Zero-point energy, tunneling, and vibrational adiabaticity in the Mu + H2 reaction
Mielke, Steven L.; Garrett, Bruce C.; Fleming, Donald G.; Truhlar, Donald G.
2015-01-09
Abstract: Isotopic substitution of muonium for hydrogen provides an unparalleled opportunity to deepen our understanding of quantum mass effects on chemical reactions. A recent topical review [Aldegunde et al., Mol. Phys. 111, 3169 (2013)] of the thermal and vibrationally-stateselected reaction of Mu with H2 raises a number of issues that are addressed here. We show that some earlier quantum mechanical calculations of the Mu + H2 reaction, which are highlighted in this review and which have been used to benchmark approximate methods, are in error by as much as 19% in the low-temperature limit. We demonstrate that an approximate treatment of the Born–Oppenheimer diagonal correction that was used in some recent studies is not valid for treating the vibrationally-state-selected reaction. We also discuss why vibrationally adiabatic potentials that neglect bend zero-point energy are not a useful analytical tool for understanding reaction rates and why vibrationally nonadiabatic transitions cannot be understood by considering tunneling through vibrationally adiabatic potentials. Finally, we present calculations on a hierarchical family of potential energy surfaces to assess the sensitivity of rate constants to the quality of the potential surface.
NASA Astrophysics Data System (ADS)
Shin, Seungha
All energy conversion inefficiencies begin with emission of resonant atomic motions, e.g., vibrations, and are declared as waste heat once these motions thermalize to equilibrium. The nonequilibrium energy occupancy of the vibrational modes can be targeted as a harvestable, low entropy energy source for direct conversion to electric energy. Since the lifetime of these resonant vibrations is short, special nanostructures are required with the appropriate tuning of the kinetics. These in turn require multiscale, multiphysics treatments. Atomic vibration is described with quasiparticle phonon in solid, and the optical phonon emission is dominant relaxation channel in semiconductors. These optical modes become over-occupied when their emission rate becomes larger than their decay rate, thus hindering energy relaxation and transport in devices. Effective removal of these phonons by drifting electrons is investigated by manipulating the electron distribution to have higher population in the low-energy states, thus allowing favorable phonon absorption. This is done through introduction, design and analysis of a heterobarrier conducting current, where the band gap is controlled by alloying, thus creating a spatial variation which is abrupt followed by a linear gradient (to ensure directed current). Self-consistent ensemble Monte Carlo simulations based on interaction kinetics between electron and phonon show that up to 19% of the phonon energy is converted to electric potential with an optimized GaAs/AlxGa1-xAs barrier structure over a range of current and electron densities, and this system is also verified through statistical entropy analysis. This direct energy conversion improves the device performance with lower operation temperature and enhances overall energy conversion efficiency. Through this study, the paradigm for harvesting the resonant atomic vibration is proposed, reversing the general role of phonon as only causing electric potential drop. Fundamentals
NASA Astrophysics Data System (ADS)
Brennan, M. J.; Tang, B.; Melo, G. Pechoto; Lopes, V.
2014-02-01
A mass-spring-damper system is at the core of both a vibration absorber and a harvester of energy from ambient vibrations. If such a device is attached to a structure that has a high impedance, then it will have very little effect on the vibrations of the structure, but it can be used to convert mechanical vibrations into electrical energy (act as an energy harvester). However, if the same device is attached to a structure that has a relatively low impedance, then the device may attenuate the vibrations as it may act as both a vibration absorber and an energy harvester simultaneously. In this paper such a device is discussed. Two situations are considered; the first is when the structure is excited with broadband random excitation and the second is when the structure is excited by a single frequency. The optimum parameters of the device for both energy harvesting and vibration attenuation are discussed for these two cases. For random excitation it is found that if the device is optimized for vibration suppression, then this is also adequate for maximizing the energy absorbed (harvested), and thus a single device can effectively suppress vibration and harvest energy at the same time. For single frequency excitation this is found not to be the case. To maximize the energy harvested, the natural frequency of the system (host structure and absorber) has to coincide with the forcing frequency, but to minimize vibration of the host structure, the natural frequency of the absorber has to coincide with the forcing frequency. In this case, therefore, a single resonator cannot effectively suppress vibration and harvest energy at the same time.
Fluctuations of internal energy flow in a vibrated granular gas.
Puglisi, Andrea; Visco, Paolo; Barrat, Alain; Trizac, Emmanuel; van Wijland, Frédéric
2005-09-09
The nonequilibrium fluctuations of power flux in a fluidized granular media have been recently measured in an experiment [Phys. Rev. Lett. 92, 164301 (2004)], which was announced to be a verification of the fluctuation relation (FR) by Gallavotti and Cohen. An effective temperature was also identified and proposed to be a useful probe for such nonequilibrium systems. We explain these results in terms of a two-temperature Poisson process. Within this model, supported by independent molecular dynamics simulations, power flux fluctuations do not satisfy the FR and the nature of the effective temperature is clarified. In the pursuit of a hypothetical global quantity fulfilling the FR, this points to the need of considering candidates other than the power flux.
Fluctuations of Internal Energy Flow in a Vibrated Granular Gas
NASA Astrophysics Data System (ADS)
Puglisi, Andrea; Visco, Paolo; Barrat, Alain; Trizac, Emmanuel; van Wijland, Frédéric
2005-09-01
The nonequilibrium fluctuations of power flux in a fluidized granular media have been recently measured in an experiment [Phys. Rev. Lett. 92, 164301 (2004)PRLTAO0031-900710.1103/PhysRevLett.92.164301], which was announced to be a verification of the fluctuation relation (FR) by Gallavotti and Cohen. An effective temperature was also identified and proposed to be a useful probe for such nonequilibrium systems. We explain these results in terms of a two-temperature Poisson process. Within this model, supported by independent molecular dynamics simulations, power flux fluctuations do not satisfy the FR and the nature of the effective temperature is clarified. In the pursuit of a hypothetical global quantity fulfilling the FR, this points to the need of considering candidates other than the power flux.
NASA Astrophysics Data System (ADS)
González Ureña, A.; Telle, H. H.; Tornero, J.
2013-01-01
A simple, inelastic electron-scattering dynamical model is presented to account for vibrational excitation in molecular adsorbates. The basic two ingredients of the theoretical model are: (i) the conservation of the total angular momentum, and (ii) the requirement of a critical time to allow for the intra-molecular energy re-arrangement of the transient negative-ion complex. The model is applied to the vibrational excitation dynamics of molecules chemisorbed at sub-monolayer conditions on ordered metal surfaces. This was exemplified for Acrylonitrile adsorbed on Cu(1 0 0), whose vibrational excitation was studied via energy loss spectra of low-energy two-photon photoemission (2PPE) electrons, and for ammonia (NH3 and ND3) adsorbed on Cu(1 0 0), being probed in a STM experiment. Fits of the model to the data allowed for deducing the energy threshold of the vibrational excitation of the Cdbnd C and Ctbnd N bonds of the ACN adsorbate molecules, and the threshold for the symmetric ν1-stretch mode excitation of adsorbed NH3/ND3. Also, information about the temporal dynamics underlying the inelastic electron scattering was gained.
NASA Astrophysics Data System (ADS)
Royston, T. J.; Singh, R.
1996-07-01
While significant non-linear behavior has been observed in many vibration mounting applications, most design studies are typically based on the concept of linear system theory in terms of force or motion transmissibility. In this paper, an improved analytical strategy is presented for the design optimization of complex, active of passive, non-linear mounting systems. This strategy is built upon the computational Galerkin method of weighted residuals, and incorporates order reduction and numerical continuation in an iterative optimization scheme. The overall dynamic characteristics of the mounting system are considered and vibratory power transmission is minimized via adjustment of mount parameters by using both passive and active means. The method is first applied through a computational example case to the optimization of basic passive and active, non-linear isolation configurations. It is found that either active control or intentionally introduced non-linearity can improve the mount's performance; but a combination of both produces the greatest benefit. Next, a novel experimental, active, non-linear isolation system is studied. The effect of non-linearity on vibratory power transmission and active control are assessed via experimental measurements and the enhanced Galerkin method. Results show how harmonic excitation can result in multiharmonic vibratory power transmission. The proposed optimization strategy offers designers some flexibility in utilizing both passive and active means in combination with linear and non-linear components for improved vibration mounts.
NASA Technical Reports Server (NTRS)
Tessarzik, J. M.; Chiang, T.; Badgley, R. H.
1973-01-01
The random vibration response of a gas bearing rotor support system has been experimentally and analytically investigated in the amplitude and frequency domains. The NASA Brayton Rotating Unit (BRU), a 36,000 rpm, 10 KWe turbogenerator had previously been subjected in the laboratory to external random vibrations, and the response data recorded on magnetic tape. This data has now been experimentally analyzed for amplitude distribution and magnetic tape. This data has now been experimentally analyzed for amplitude distribution and frequency content. The results of the power spectral density analysis indicate strong vibration responses for the major rotor-bearing system components at frequencies which correspond closely to their resonant frequencies obtained under periodic vibration testing. The results of amplitude analysis indicate an increasing shift towards non-Gaussian distributions as the input level of external vibrations is raised. Analysis of axial random vibration response of the BRU was performed by using a linear three-mass model. Power spectral densities, the root-mean-square value of the thrust bearing surface contact were calculated for specified input random excitation.
LDV measurement of bird ear vibrations to determine inner ear impedance and middle ear power flow
NASA Astrophysics Data System (ADS)
Muyshondt, Pieter G. G.; Pires, Felipe; Dirckx, Joris J. J.
2016-06-01
The mechanical behavior of the middle ear structures in birds and mammals is affected by the fluids in the inner ear (IE) that are present behind the oval window. In this study, the aim was to gather knowledge of the acoustic impedance of the IE in the ostrich, to be able to determine the effect on vibrations and power flow in the single-ossicle bird middle ear for future studies. To determine the IE impedance, vibrations of the ossicle were measured for both the quasi-static and acoustic stimulus frequencies. In the acoustic regime, vibrations were measured with a laser Doppler vibrometer and electromagnetic stimulation of the ossicle. The impedance of the inner ear could be determined by means of a simple RLC model in series, which resulted in a stiffness reactance of KIE = 0.20.1012 Pa/m3, an inertial impedance of MIE = 0.652.106 Pa s2/m3, and a resistance of RIE = 1.57.109 Pa s/m. The measured impedance is found to be considerably smaller than what is found for the human IE.
NASA Astrophysics Data System (ADS)
Wu, Dan; Guyomar, Daniel; Richard, Claude
2013-04-01
A new global approach for improved vibration damping of smart structure, based on global energy redistribution by means of a network of piezoelectric elements is proposed. It is basically using semi-active Synchronized Switch Damping technique. SSD technique relies on a cumulative build-up of the voltage resulting from the continuous switching and it was shown that the performance is strongly related to this voltage. The increase of the piezoelectric voltage results in improvement of the damping performance. External voltage sources or improved switching sequences were previously designed to increase this voltage in the case of single piezoelectric element structure configurations. This paper deals with extended structure with many embedded piezoelectric elements. The proposed strategy consist of using an electric network made with non-linear component and switches in order to set up and control a low-loss energy transfer from source piezoelements extracting the vibration energy of the structure and oriented toward a given piezoelement in order to increase its operative energy for improving a given mode damping. This paper presents simulation of a clamped plate with four piezoelectric elements implemented in the Matlab/SimulinkTM environment and SimscapeTM library. The various simulation cases show the relationship between the damping performance on a given targeted mode and the established power flow. SSDD and SSDT are two proposed original networks. Performances are compared to the SSDI baseline. A damping increase of 18dB can be obtained even with a weakly coupled piezoelectric element in the multi-sine excitation case. This result proves the importance of new global non-linear multi-actuator strategies for improved vibration damping of extended smart structure.
Fiber optic vibration sensor for high-power electric machines realized using 3D printing technology
NASA Astrophysics Data System (ADS)
Igrec, Bojan; Bosiljevac, Marko; Sipus, Zvonimir; Babic, Dubravko; Rudan, Smiljko
2016-03-01
The objective of this work was to demonstrate a lightweight and inexpensive fiber-optic vibration sensor, built using 3D printing technology, for high-power electric machines and similar applications. The working principle is based on modulating the light intensity using a blade attached to a bendable membrane. The sensor prototype was manufactured using PolyJet Matrix technology with DM 8515 Grey 35 Polymer. The sensor shows linear response, expected bandwidth (< 150 Hz), and from our measurements we estimated the damping ratio for used polymer to be ζ ≍ 0.019. The developed prototype is simple to assemble, adjust, calibrate and repair.
Vibrational energy transfer and anisotropy decay in liquid water: is the Förster model valid?
Yang, Mino; Li, Fu; Skinner, J L
2011-10-28
Ultrafast pump-probe anisotropy experiments have been performed on liquid H(2)O and D(2)O. In both cases, the anisotropy decay is extremely fast (on the order of 100 or 200 fs) and is presumed due to resonant vibrational energy transfer. The experiments have been interpreted in terms of the Förster theory, wherein the rate constant for intermolecular hopping transport is proportional to the inverse sixth power of the distance between the vibrational chromophores. In particular, the anisotropy decay is assumed to be simply related to the survival probability as calculated with the Förster theory. While the theory fits the data well, and is a reasonable model for these systems, there are several assumptions in the theory that might be suspect for water. Using our mixed quantum/classical model for vibrational spectroscopy and dynamics in liquid water, which agrees well with anisotropy decay experiments on the pure liquids as well as H(2)O/D(2)O mixtures, we critically analyze both the survival probability and anisotropy decay, in order to assess the applicability of the Förster theory.
Power Supplies for High Energy Particle Accelerators
NASA Astrophysics Data System (ADS)
Dey, Pranab Kumar
2016-06-01
The on-going research and the development projects with Large Hadron Collider at CERN, Geneva, Switzerland has generated enormous enthusiasm and interest amongst all to know about the ultimate findings on `God's Particle'. This paper has made an attempt to unfold the power supply requirements and the methodology adopted to provide the stringent demand of such high energy particle accelerators during the initial stages of the search for the ultimate particles. An attempt has also been made to highlight the present status on the requirement of power supplies in some high energy accelerators with a view that, precautionary measures can be drawn during design and development from earlier experience which will be of help for the proposed third generation synchrotron to be installed in India at a huge cost.
Water Desalination Systems Powered by Solar Energy
NASA Astrophysics Data System (ADS)
Barseghyan, A.
2015-12-01
The supply of potable water from polluted rivers, lakes, unsafe wells, etc. is a problem of high priority. One of the most effective methods to obtain low cost drinking water is desalination. Advanced water treatment system powered by Solar Energy and based on electrodialysis for water desalination and purification, is suggested. Technological and economic evaluations and the benefits of the suggested system are discussed. The Advanced Water Treatment System proposed clears water not only from different salts, but also from some infections, thus decreasing the count of diseases which are caused by the usage of non-clear water. Using Solar Energy makes the system stand alone which is convenient to use in places where power supply is problem.
Energy, Power and Thermal Research Overview
2010-09-01
Research Overview Rick Fingers, Ph.D. Chief Energy/Power/Thermal Division Propulsion Directorate Air Force Research ... Air Vehicles Sensors AFOSR 5 AFRL People & Facilities • 10 Major R&D Sites across US • 40 Sites World-Wide • $40B Real Property & Capital throughout... AFRL • 5,764 Government Employees – 4570 Air Force Civilian – 1194 Military • 3,844 Onsite Contractors 6 Propulsion Directorate’s Strategic
Electric Power From Ambient Energy Sources
DeSteese, John G.; Hammerstrom, Donald J.; Schienbein, Lawrence A.
2000-10-03
This report summarizes research on opportunities to produce electric power from ambient sources as an alternative to using portable battery packs or hydrocarbon-fueled systems in remote areas. The work was an activity in the Advanced Concepts Project conducted by Pacific Northwest National Laboratory (PNNL) for the Office of Research and Development in the U.S. Department of Energy Office of Nonproliferation and National Security.
NASA Astrophysics Data System (ADS)
Argenti, L.; Plésiat, E.; Kukk, E.; Ueda, K.; Decleva, P.; Martín, F.
2012-11-01
Distinct oscillations in vibrationally resolved cross section ratios for the photoionization of CH4 from the C 1s orbital at photon energies as high as 1keV are predicted. The oscillations are attributed to the different relative vibrational excitation due to the scattering of the photoelectron by the peripheral hydrogen atoms. The latter effect is also responsible for the well known EXAFS oscillations in the integrated photoelectron spectrum. The calculations are performed with an ab-initio DFT method [1], as well as with a single-particle semi-analytical model, which incorporate both the effect of the nuclear recoil and of the Coulomb corrections.
NASA Astrophysics Data System (ADS)
Dudka, A.; Basset, P.; Cottone, F.; Blokhina, E.; Galayko, D.
2013-12-01
This paper reports on an electrostatic Vibration Energy Harvester (e-VEH) system, for which the energy conversion process is initiated with a low bias voltage and is compatible with wideband stochastic external vibrations. The system employs the auto-synchronous conditioning circuit topology with the use of a novel dedicated integrated low-power high-voltage switch that is needed to connect the charge pump and flyback - two main parts of the used conditioning circuit. The proposed switch is designed and implemented in AMS035HV CMOS technology. Thanks to the proposed switch device, which is driven with a low-voltage ground-referenced logic, the e-VEH system may operate within a large voltage range, from a pre-charge low voltage up to several tens volts. With such a high-voltage e-VEH operation, it is possible to obtain a strong mechanical coupling and a high rate of vibration energy conversion. The used transducer/resonator device is fabricated with a batch-processed MEMS technology. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110-170 Hz, up to 0.75 μW of net electrical power has been harvested with our system. This work presents an important milestone in the challenge of designing a fully integrated smart conditioning interface for the capacitive e-VEHs.
Energy Storage Applications in Power Systems with Renewable Energy Generation
NASA Astrophysics Data System (ADS)
Ghofrani, Mahmoud
In this dissertation, we propose new operational and planning methodologies for power systems with renewable energy sources. A probabilistic optimal power flow (POPF) is developed to model wind power variations and evaluate the power system operation with intermittent renewable energy generation. The methodology is used to calculate the operating and ramping reserves that are required to compensate for power system uncertainties. Distributed wind generation is introduced as an operational scheme to take advantage of the spatial diversity of renewable energy resources and reduce wind power fluctuations using low or uncorrelated wind farms. The POPF is demonstrated using the IEEE 24-bus system where the proposed operational scheme reduces the operating and ramping reserve requirements and operation and congestion cost of the system as compared to operational practices available in the literature. A stochastic operational-planning framework is also proposed to adequately size, optimally place and schedule storage units within power systems with high wind penetrations. The method is used for different applications of energy storage systems for renewable energy integration. These applications include market-based opportunities such as renewable energy time-shift, renewable capacity firming, and transmission and distribution upgrade deferral in the form of revenue or reduced cost and storage-related societal benefits such as integration of more renewables, reduced emissions and improved utilization of grid assets. A power-pool model which incorporates the one-sided auction market into POPF is developed. The model considers storage units as market participants submitting hourly price bids in the form of marginal costs. This provides an accurate market-clearing process as compared to the 'price-taker' analysis available in the literature where the effects of large-scale storage units on the market-clearing prices are neglected. Different case studies are provided to
Chung, Pao-Hung; Lin, Guan-Lun; Liu, Chiang; Chuang, Long-Ren; Shiang, Tzyy-Yuang
2013-01-01
The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key pointsEight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population.The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism.Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other.
Chung, Pao-Hung; Lin, Guan-Lun; Liu, Chiang; Chuang, Long-Ren; Shiang, Tzyy-Yuang
2013-01-01
The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key points Eight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population. The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism. Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other
NASA Astrophysics Data System (ADS)
Lu, Y.; Cottone, F.; Boisseau, S.; Galayko, D.; Marty, F.; Basset, P.
2015-12-01
This paper reports for the first time a MEMS electrostatic vibration energy harvester (e-VEH) with corona-charged vertical electrets on its electrodes. The bandwidth of the 1-cm2 device is extended in low and high frequencies by nonlinear elastic stoppers. With a bias voltage of 46 V (electret@21 V + DC external source@25 V) between the electrodes, the RMS power of the device reaches 0.89 μW at 33 Hz and 6.6 μW at 428 Hz. The -3dB frequency band including the hysteresis is 223∼432 Hz, the one excluding the hysteresis 88∼166 Hz. We also demonstrate the charging of a 47 μF capacitor used for powering a wireless and autonomous temperature sensor node with a data transmission beyond 10 m at 868 MHz.
Chaos control applied to piezoelectric vibration-based energy harvesting systems
NASA Astrophysics Data System (ADS)
Barbosa, W. O. V.; De Paula, A. S.; Savi, M. A.; Inman, D. J.
2015-11-01
Chaotic behavior presents intrinsic richness due to the existence of an infinity number of unstable periodic orbits (UPOs). The possibility of stabilizing these periodic patterns with a small amount of energy makes this kind of response interesting to various dynamical systems. Energy harvesting has as a goal the use of available mechanical energy by promoting a conversion into electrical energy. The combination of these two approaches may establish autonomous systems where available environmental mechanical energy can be employed for control purposes. Two different goals can be defined as priority, allowing a change between them: vibration reduction and energy harvesting enhancement. This work deals with the use of harvested energy to perform chaos control. Both control actuation and energy harvesting are induced employing piezoelectric materials, in a simultaneous way. A bistable piezomagnetoelastic structure subjected to harmonic excitations is investigated as a case study. Numerical simulations show situations where it is possible to perform chaos control using only the energy generated by the harvesting system.
Power and energy of exploding wires
NASA Astrophysics Data System (ADS)
Valancius, Cole J.; Garasi, Christopher J.; O'Malley, Patrick D.
2017-01-01
Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a more broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.
Perspectives on renewable energy and Village Power
Hoffman, A.R.
1997-12-01
The author provides a brief overview of the role the Department of Energy has been playing in the area of renewable energy sources and their applications at a village level. Energy demand is rising sharply, and shortages are becoming more acute. Developing countries will present a large demand, and market opportunity over the next 40 years. Environmental concerns are a factor in the choice for what sources to promote and develop. The author touches on the features of renewable sources which makes them attractive to DOE for some applications, and what the goals of the department are in supporting this technology. Examples of applications at the level of village power are presented for both the US and abroad.
Roles of the Excitation in Harvesting Energy from Vibrations
Zhang, Hui; Ma, Tianwei
2015-01-01
The study investigated the role of excitation in energy harvesting applications. While the energy ultimately comes from the excitation, it was shown that the excitation may not always behave as a source. When the device characteristics do not perfectly match the excitation, the excitation alternately behaves as a source and a sink. The extent to which the excitation behaves as a sink determines the energy harvesting efficiency. Such contradictory roles were shown to be dictated by a generalized phase defined as the instantaneous phase angle between the velocity of the device and the excitation. An inductive prototype device with a diamagnetically levitated seismic mass was proposed to take advantage of the well established phase changing mechanism of vibro-impact to achieve a broader device bandwidth. Results suggest that the vibro-impact can generate an instantaneous, significant phase shift in response velocity that switches the role of the excitation. If introduced properly outside the resonance zone it could dramatically increase the energy harvesting efficiency. PMID:26496183
Pietanza, L. D. Colonna, G.; D'Ammando, G.; Laricchiuta, A.; Capitelli, M.
2016-01-15
A Boltzmann equation, in the presence of superelastic vibrational and electronic collisions and of electron-electron Coulomb collisions, has been solved in CO{sub 2} plasma in discharge and post discharge conditions. Superelastic vibrational collisions play an important role in affecting the electron energy distribution function (eedf) in a wide range of the reduced electric field E/N and of vibrational temperatures characterizing the vibrational modes of CO{sub 2}. An important result is the dependence of fractional power losses and of the relevant rate coefficients on the vibrational temperatures of the system. Superelastic electronic collisions, on the other hand, are the main processes affecting eedf and related quantities in the post discharge conditions (i.e., E/N = 0). In particular at low vibrational temperatures, the superelastic electronic collisions form an important plateau in the eedf, largely influencing the rate coefficients and the fractional power transfer.
Reactive Power Compensation Using an Energy Management System
2014-09-01
Power electronics enabled energy management systems,” in Proceedings of IEEE Applied Power Electronics Conference, Long Beach, CA, Mar. 2013, pp...DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE REACTIVE POWER COMPENSATION USING AN ENERGY MANAGEMENT SYSTEM 5. FUNDING NUMBERS 6. AUTHOR(S...efficiency is the reactive power demand on the grid. Inductive power demand reduces power factor, increases energy losses during transmission, limits real
Vibration energy harvesting using the nonlinear oscillations of a magnetostrictive material
NASA Astrophysics Data System (ADS)
Tsutsumi, Erika; del Rosario, Zachary; Lee, Christopher
2012-04-01
A novel magnetostrictive-material-based device concept to convert ambient mechanical vibration into electricity has been designed, fabricated, and tested. In order to harvest energy over a greater frequency range as compared to state-of- the-art devices, an L-shaped beam which is tuned so that the first two (bending) natural frequencies have a (near) two-to-one ratio is used as a mechanical transducer to generate nonlinear oscillations. Under harmonic excitation, an internal resonance or autoparametric, dynamic response can occur in which one vibration mode parametrically excites a second vibration mode resulting in significant displacement of both modes over an extended frequency range. A magnetostrictive material, Metglas 2605SA1, is used to convert vibration into electricity. Vibration-induced strain in the Metglas changes its magnetization which in turn generates current in a coil of wire. Metglas is highly flexible so it can undergo large displacement and does not fatigue under extended excitation. Demonstration devices are used to study how this nonlinear response can be exploited to generate electricity under single-frequency, harmonic and random base excitation.
Random vibration analysis of the Topaz-II nuclear reactor power system. Master`s thesis
Campbell, S.E.
1995-06-01
The TOPAZ-II Ya-21U is one of six Russian made space nuclear power systems which is based on theomionic power conversion. The U.S. is presently analyzing TOPAZ-II to determine the reliability and feasibility of using this system. A structural analysis test was conducted on the TOPAZ unit in May 1993 to provide data from which modal parameters could be identified. This test showed the fundamental frequency to be 10.5 Hz, yet the test results that the Russians conducted identified a fundamental frequency of 5 Hz. Another finite element model was created incorporating new developments in TOPAZ-II and modifications to the finite element model to better simulate the mass properties of the TOPAZ-II2. A second structural analysis test was conducted on the TOPAZ unit 06-09 September 1994. This thesis focuses on the random vibration analysis of the TOPAZ-II Ya-2lU utilizing the most recent test results and the Master Series (updated version) I-DEAS software. The modal respose of the model and simulated random vibration tests were within 8.33%. This model is a feasible tool which can be used to analyze the TOPAZ unit without testing the unit to fatigue.
NASA Astrophysics Data System (ADS)
Herdic, Peter C.; Houston, Brian H.; Corsaro, Robert D.; Judge, John A.
2002-11-01
Implementation of active control techniques in mechanical vibration isolation systems has been a challenging problem for a number of years where numerous physical control laws have been explored. An energy-based approach to the problem involving the energy transfer or power flow through the mount into the base structure is a first-principles approach to developing control laws and evaluating the system performance. A lumped-parameter model of a passive-active hybrid isolation mount has been developed and validated with experimental data. The mount device has a conventional passive compliant spring, embedded force and velocity sensors, and a piezoceramic actuation layer. This study investigates a complete set of possible layer configurations, that is, the optimal placement of sensors and actuator relative to the passive compliant isolator element. A number of different local physical control laws are examined and the level of power flow through the mount is used to evaluate the performance for the matrix of possible implementations. These results will be discussed with particular emphasis placed on the optimal control configuration and laws, and the related physics. a)Also with SFA, Inc., Largo, MD 20774.
NASA Astrophysics Data System (ADS)
Kruglova, T. V.
2004-01-01
The detailed spectroscope information about highly excited molecules and radicals such us as H+3, H2, HI, H2O, CH2 is needed for a number of applications in the field of laser physics, astrophysics and chemistry. Studies of highly excited molecular vibration-rotation states face several problems connected with slowly convergence or even divergences of perturbation expansions. The physical reason for a perturbation expansion divergence is the large amplitude motion and strong vibration-rotation coupling. In this case one needs to use the special method of series summation. There were a number of papers devoted to this problem: papers 1-10 in the reference list are only example of studies on this topic. The present report is aimed at the application of GET method (Generalized Euler Transformation) to the diatomic molecule. Energy levels of a diatomic molecule is usually represented as Dunham series on rotational J(J+1) and vibrational (V+1/2) quantum numbers (within the perturbation approach). However, perturbation theory is not applicable for highly excited vibration-rotation states because the perturbation expansion in this case becomes divergent. As a consequence one need to use special method for the series summation. The Generalized Euler Transformation (GET) is known to be efficient method for summing of slowly convergent series, it was already used for solving of several quantum problems Refs.13 and 14. In this report the results of Euler transformation of diatomic molecule Dunham series are presented. It is shown that Dunham power series can be represented of functional series that is equivalent to its partial summation. It is also shown that transformed series has the butter convergent properties, than the initial series.
Statistics of power injection in a plate set into chaotic vibration
NASA Astrophysics Data System (ADS)
Cadot, O.; Boudaoud, A.; Touzé, C.
2008-12-01
A vibrating plate is set into a chaotic state of wave turbulence by either a periodic or a random local forcing. Correlations between the forcing and the local velocity response of the plate at the forcing point are studied. Statistical models with fairly good agreement with the experiments are proposed for each forcing. Both distributions of injected power have a logarithmic cusp for zero power, while the tails are Gaussian for the periodic driving and exponential for the random one. The distributions of injected work over long time intervals are investigated in the framework of the fluctuation theorem, also known as the Gallavotti-Cohen theorem. It appears that the conclusions of the theorem are verified only for the periodic, deterministic forcing. Using independent estimates of the phase space contraction, this result is discussed in the light of available theoretical framework.
Ab initio potential energy surface and vibration-rotation energy levels of silicon dicarbide, SiC2.
Koput, Jacek
2016-10-05
The accurate ground-state potential energy surface of silicon dicarbide, SiC2 , has been determined from ab initio calculations using the coupled-cluster approach. Results obtained with the conventional and explicitly correlated coupled-cluster methods were compared. The core-electron correlation, higher-order valence-electron correlation, and scalar relativistic effects were taken into account. The potential energy barrier to the linear SiCC configuration was predicted to be 1782 cm(-1) . The vibration-rotation energy levels of the SiC2 , (29) SiC2 , (30) SiC2 , and SiC(13) C isotopologues were calculated using a variational method. The experimental vibration-rotation energy levels of the main isotopologue were reproduced to high accuracy. In particular, the experimental energy levels of the highly anharmonic vibrational ν3 mode of SiC2 were reproduced to within 6.7 cm(-1) , up to as high as the v3 = 16 state.
A budget of energy transfer in a sustained vocal folds vibration in glottis
NASA Astrophysics Data System (ADS)
Zhang, Lucy; Yang, Jubiao; Krane, Michael
2016-11-01
A set of force and energy balance equations using the control volume approach is derived based on the first principles of physics for a sustained vocal folds vibration in glottis. The control volume analysis is done for compressible airflow in a moving and deforming control volume in the vicinity of the vocal folds. The interaction between laryngeal airflow and vocal folds are successfully simulated using the modified Immersed Finite Element Method (mIFEM), a fully coupled approach to simulate fluid-structure interactions. Detailed mathematical terms are separated out for deeper physical understanding and utilization of mechanical energy is quantified with the derived equation. The results show that majority of energy input is consumed for driving laryngeal airflow, while a smaller portion is for compensating viscous losses in and sustaining the vibration of the vocal folds. We acknowledge the funding support of NIH 2R01DC005642-10A1.
Exploitation of a tristable nonlinear oscillator for improving broadband vibration energy harvesting
NASA Astrophysics Data System (ADS)
Zhou, Shengxi; Cao, Junyi; Lin, Jing; Wang, Zezhou
2014-09-01
Numerical and experimental investigations of a broadband vibration energy harvester with triple-well are presented. The nonlinear restoring force of the tristable oscillator is experimentally identified as a high order polynomial that depends on the relative spacing and locations of the magnets in the magnetically coupled piezoelectric cantilever. Simulations and experiments are performed at different harmonic excitation levels ranging from 10 to 35 Hz. The tristable energy harvester possesses the unique jump characteristics of oscillation center stemming from excitation level and initial displacements. Its broad frequency range of 15.1-32.5 Hz is obtained from the transition among three wells. It is also demonstrated that the tristable nonlinear oscillator will be more helpful to improve the broadband performance for harvesting vibration energy under low frequency excitations.
On the nature of intramolecular vibrational energy transfer in dense molecular environments
NASA Astrophysics Data System (ADS)
von Benten, Rebekka S.; Abel, Bernd
2010-12-01
Transient femtosecond-IR-pump-UV-absorption probe-spectroscopy has been employed to shed light on the nature of intramolecular vibrational energy transfer (IVR) in dense molecular environments ranging from the diluted gas phase to the liquid. A general feature in our experiments and those of others is that IVR proceeds via multiple timescales if overtones or combination vibrations of high frequency modes are excited. It has been found that collisions enhance IVR if its (slower) timescales can compete with collisions. This enhancement is, however, much more weaker and rather inefficient as opposed to the effect of collisions on intermolecular energy transfer which is well known. In a series of experiments we found that IVR depends not significantly on the average energy transferred in a collision but rather on the number of collisions. The collisions are much less efficient in affecting IVR than VET. We conclude that collision induced broadening of vibrational energy levels reduces the energy gaps and enhances existing couplings between tiers. The present results are an important step forward to rationalize and understand apparently different and not consistent results from different groups on different molecular systems between gas and liquid phases.
Modelling of a Bi-axial Vibration Energy Harvester
2013-05-01
in an induced electromotive force (EMF) in the wire-coil by Faraday’s Law of Induction [14], and hence power output across an electrical load...TN-1174 assumed solution into a series solution. HAM was applied to the equation developed in section 2.2.1 in a similar fashion to previous results...cos()(’)(’ )(’)(’)( 5 5 53 3 3 1 2 akAkA kAAA (7) The HAM approach produces series solutions to the new
Spectroscopy and Chemistry of Molecules with High Vibrational Energy Content.
1982-10-15
dissociation channels, viz., HC elimination, ring scission, and C=Cl homolysis. (Francisco and Steinfeld, 1981; Lawrance et al., 1981). The species CF300CF 3...Trifluoromethyl) peroxide", Intl. J. Chem. Kinetics, 13, 627 (1981). W.D. Lawrance , J. Silberstein, Zhang Fu-min, Zhu Qing-shi, J.S. Francisco, and J...75, 3153 (1981). J.S. Francisco, W.D. Lawrance , J.I. Steinfeld, and R.G. Gilbert, "Infrared Multiphoton Decomposition and Energy-Dependent
Dynamic treatment of vibrational energy relaxation in a heterogeneous and fluctuating environment.
Fujisaki, Hiroshi; Stock, Gerhard
2008-10-07
A computational approach to describe the energy relaxation of a high-frequency vibrational mode in a fluctuating heterogeneous environment is outlined. Extending previous work [H. Fujisaki, Y. Zhang, and J. E. Straub, J. Chem. Phys. 124, 144910 (2006)], second-order time-dependent perturbation theory is employed which includes the fluctuations of the parameters in the Hamiltonian within the vibrational adiabatic approximation. This means that the time-dependent vibrational frequencies along a molecular dynamics trajectory are obtained via a partial geometry optimization of the solute with fixed solvent and a subsequent normal mode calculation. Adopting the amide I mode of N-methylacetamide in heavy water as a test problem, it is shown that the inclusion of dynamic fluctuations may significantly change the vibrational energy relaxation. In particular, it is found that relaxation occurs in two phases, because for short times (approximately < 200 fs) the spectral density appears continuous due to the frequency-time uncertainty relation, while at longer times the discrete nature of the bath becomes apparent. Considering the excellent agreement between theory and experiment, it is speculated if this behavior can explain the experimentally obtained biphasic relaxation the amide I mode of N-methylacetamide.
Jia, Yu; Du, Sijun; Seshia, Ashwin A.
2016-01-01
This paper contends to be the first to report the experimental observation of up to 28 orders of parametric resonance, which has thus far only been envisioned in the theoretical realm. While theory has long predicted the onset of n orders of parametric resonance, previously reported experimental observations have been limited up to about the first 5 orders. This is due to the rapid narrowing nature of the frequency bandwidth of the higher instability intervals, making practical accessibility increasingly more difficult. Here, the authors have experimentally confirmed up to 28 orders of parametric resonance in a micromachined membrane resonator when electrically undamped. While the implication of this finding spans across the vibration dynamics and transducer application spectrum, the particular significance of this work is to broaden the accumulative operational frequency bandwidth of vibration energy harvesting for enabling self-powered microsystems. Up to 5 orders were recorded when driven at 1.0 g of acceleration across a matched load of 70 kΩ. With a natural frequency of 980 Hz, the fundamental mode direct resonance had a −3 dB bandwidth of 55 Hz, in contrast to the 314 Hz for the first order parametric resonance; furthermore, the half power bands of all 5 orders accumulated to 478 Hz. PMID:27445205
NASA Astrophysics Data System (ADS)
Komuro, Atsushi; Takahashi, Kazunori; Ando, Akira
2015-10-01
Vibration-to-translation (V-T) energy transfer in atmospheric-pressure streamer discharge is numerically simulated using a two-dimensional electro-hydrodynamic model. The model includes state-to-state vibrational kinetics in humid air and is coupled with the compressible flow equation of the gas fluid. The vibrational distribution of {{\\text{O}}2}(v) reaches equilibrium more quickly than that of {{\\text{N}}2}(v) , whereas the energy released from {{\\text{O}}2}(v) does not increase the gas temperature. In humid air, the decay rate of the vibrational energy of {{\\text{N}}2}(v) is accelerated by the V-T energy transfer through water molecules and the energy heats the gas. However, the increase in gas temperature due to V-T energy transfer is not always seen because it competes with thermal diffusion.
Sound power radiation from a vibrating structure in terms of structure-dependent radiation modes
NASA Astrophysics Data System (ADS)
Ji, Lin; Bolton, J. Stuart
2015-01-01
As a good supplement of conventional acoustic radiation modes (a-modes), a set of so-called "structure-dependent radiation modes" (s-modes) is introduced to describe the sound power radiation from a vibrating structure. Differing from a-modes, s-modes are determined by not only the acoustic resistance matrix of the structure but also the frequency-independent normal modes of the structure. Such a new definition has the following main advantages over the conventional one: (1) it can reflect directly the influences of dynamic properties (e.g., boundary conditions) of the structures on its sound power radiation; (2) the number of s-modes generated is generally less than that of a-modes since the former depends on the number of structural modes involved in the vibration while the latter depends on the number of segmented elemental radiators of the structure, and consequently, the demand for large data storage can be greatly alleviated, especially for large structures and/or higher frequency vibrations; (3) the set of s-modes possesses a better convergence than that of a-modes because the higher ordered s-modes can decay more rapidly than the same ordered a-modes. Two baffled, finite, models, i.e., a simple beam and a thin plate, are employed to investigate numerically the acoustic properties of s-modes, and then compared with those of a-modes. It has been shown that the two sets of radiation modes share a very similar frequency-dependent behavior in that the radiation efficiency falls off very rapidly with increasing mode order at low frequency range (typically with kl<1). Meanwhile, the number of s-modes required to describe the total sound power radiation is found to be the same as that of a-modes. Consequently, an appropriate truncation of a-modes can be achieved by using the number of vibrational modes involved. Nevertheless, the odd-ordered (even-ordered) s-modes are found only associated with the odd-numbered (even-ordered) structural modes. In case of only few
Radiant Energy Power Source for Jet Aircraft
Doellner, O.L.
1992-02-01
This report beings with a historical overview on the origin and early beginnings of Radiant Energy Power Source for Jet Aircraft. The report reviews the work done in Phase I (Grant DE-FG01-82CE-15144) and then gives a discussion of Phase II (Grant DE-FG01-86CE-15301). Included is a reasonably detailed discussion of photovoltaic cells and the research and development needed in this area. The report closes with a historical perspective and summary related to situations historically encountered on projects of this nature. 15 refs.
Energy and power limits for microbial activity
NASA Astrophysics Data System (ADS)
LaRowe, D.; Amend, J.
2014-12-01
The goal of this presentation is to describe a quantitative framework for determining how energy limits microbial activity, biomass and, ultimately, biogeochemical processes. Although this model can be applied to any environment, its utility is demonstrated in marine sediments, which are an attractive test habitat because they encompass a broad spectrum of energy levels, varying amounts of biomass and are ubiquitous. The potential number of active microbial cells in Arkonas Basin (Baltic Sea) sediments are estimated as a function of depth by quantifying the amount of energy that is available to them and the rate at which it is supplied: power. The amount of power supplied per cubic centimeter of sediment is determined by calculating the Gibbs energy of fermentation and sulfate reduction in combination with the rate of particulate organic carbon, POC, degradation. The Reactive Continuum Model (Boudreau and Ruddick, 1991), RCM, is used to determine the rate at which POC is made available for microbial consumption. The RCM represents POC as containing a range of different types of organic compounds whose ability to be consumed by microorganisms varies as a function of the age of the sediment and on the distribution of compound types that were initially deposited. The sediment age model and RCM parameters determined by (Mogollon et al., 2012) are used. The power available for fermentation and sulfate reduction coupled to H2 and acetate oxidation varies from 10-8 W cm-3 at the sediment water interface to between 10-11 - 10-12 W cm-3 at 3.5 meters below the seafloor, mbsf. Using values of maintenance powers for each of these catabolic activities taken from the literature, the total number of active cells in these sediments similarly decreases from just less than 108 cell cm-3 at the SWI to 4.6 x 104 cells cm-3 at 3.5 mbsf. The number of moles of POC decreases from 2.6 x 10-5 to 9.5 x 10-6, also becoming more recalcitrant with depth. Boudreau, B. P. and Ruddick, B. R
Photovoltaic power - An important new energy option
NASA Technical Reports Server (NTRS)
Ferber, R. R.
1983-01-01
A review of photovoltaic (PV) power technology is presented with an emphasis of PV as an economical and technically feasible alternative source of energy. The successful completion of the development and transfer of emerging low-cost technologies into a fully commercialized status are identified as the means to the realization of this option's full potential. The DOE National Photovoltaics Program, a significant sponsor of PV R&D, expects both flat-plate and concentrator collectors to meet established cost targets. Citing the DOE large flat-plate grid-connected system project of the Sacramento Municipal Utility District, current technology modules priced at near $5/Wp (1983 dollars) are steadily reducing costs. A recent DOE study suggests that PV-generated electricity produced at a 30-year levelized cost of 15 cents per kWh would represent a viable energy supply alternative for the nation.
Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
Offenhaeuser, F.
1987-01-01
The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.
NASA Astrophysics Data System (ADS)
Heo, YongHwa; Kim, Kwang-joon
2015-02-01
While the vibration power for a set of harmonic force and velocity signals is well defined and known, it is not as popular yet for a set of stationary random force and velocity processes, although it can be found in some literatures. In this paper, the definition of the vibration power for a set of non-stationary random force and velocity signals will be derived for the purpose of a time-frequency analysis based on the definitions of the vibration power for the harmonic and stationary random signals. The non-stationary vibration power, defined as the short-time average of the product of the force and velocity over a given frequency range of interest, can be calculated by three methods: the Wigner-Ville distribution, the short-time Fourier transform, and the harmonic wavelet transform. The latter method is selected in this paper because band-pass filtering can be done without phase distortions, and the frequency ranges can be chosen very flexibly for the time-frequency analysis. Three algorithms for the time-frequency analysis of the non-stationary vibration power using the harmonic wavelet transform are discussed. The first is an algorithm for computation according to the full definition, while the others are approximate. Noting that the force and velocity decomposed into frequency ranges of interest by the harmonic wavelet transform are constructed with coefficients and basis functions, for the second algorithm, it is suggested to prepare a table of time integrals of the product of the basis functions in advance, which are independent of the signals under analysis. How to prepare and utilize the integral table are presented. The third algorithm is based on an evolutionary spectrum. Applications of the algorithms to the time-frequency analysis of the vibration power transmitted from an excitation source to a receiver structure in a simple mechanical system consisting of a cantilever beam and a reaction wheel are presented for illustration.
NASA Astrophysics Data System (ADS)
Anton, S. R.; Taylor, S. G.; Raby, E. Y.; Farinholt, K. M.
2013-03-01
With a global interest in the development of clean, renewable energy, wind energy has seen steady growth over the past several years. Advances in wind turbine technology bring larger, more complex turbines and wind farms. An important issue in the development of these complex systems is the ability to monitor the state of each turbine in an effort to improve the efficiency and power generation. Wireless sensor nodes can be used to interrogate the current state and health of wind turbine structures; however, a drawback of most current wireless sensor technology is their reliance on batteries for power. Energy harvesting solutions present the ability to create autonomous power sources for small, low-power electronics through the scavenging of ambient energy; however, most conventional energy harvesting systems employ a single mode of energy conversion, and thus are highly susceptible to variations in the ambient energy. In this work, a multi-source energy harvesting system is developed to power embedded electronics for wind turbine applications in which energy can be scavenged simultaneously from several ambient energy sources. Field testing is performed on a full-size, residential scale wind turbine where both vibration and solar energy harvesting systems are utilized to power wireless sensing systems. Two wireless sensors are investigated, including the wireless impedance device (WID) sensor node, developed at Los Alamos National Laboratory (LANL), and an ultra-low power RF system-on-chip board that is the basis for an embedded wireless accelerometer node currently under development at LANL. Results indicate the ability of the multi-source harvester to successfully power both sensors.
Vázquez, Juana; Harding, Michael E; Stanton, John F; Gauss, Jürgen
2011-05-10
A variational method for the calculation of low-lying vibrational energy levels of molecules with small amplitude vibrations is presented. The approach is based on the Watson Hamiltonian in rectilinear normal coordinates and characterized by a quasi-analytic integration over the kinetic energy operator (KEO). The KEO beyond the harmonic approximation is represented by a Taylor series in terms of the rectilinear normal coordinates around the equilibrium configuration. This formulation of the KEO enables its extension to arbitrary order until numerical convergence is reached for those states describing small amplitude motions and suitably represented with a rectilinear system of coordinates. A Gauss-Hermite quadrature grid representation of the anharmonic potential is used for all the benchmark examples presented. Results for a set of molecules with linear and nonlinear configurations, i.e., CO2, H2O, and formyl fluoride (HFCO), illustrate the performance of the method and the versatility of our implementation.
Milosevic, Matija; McConville, Kristiina M V
2007-01-01
This study considers the use of hand-held power tools and the exposure of a large number of employees to hand-arm vibrations in work settings as well as the harmful effects that such exposure has on health and safety. The major objective of the project was the development of a diagnostic device for the detection and monitoring of the vibrations produced during work activities in a natural working environment and to analyze the impact of the vibrations on workers during different work operations. The developed device for vibration monitoring is based on the latest generation MEMS tri-axis accelerometer with a wireless link with the PC station. This study demonstrates the use of the device in evaluating the level of protection that gloves provide concerning the level of vibrations during work operations. The initial evaluation shows that the proposed solution provides an effective multifunctional, low-cost diagnostic device for vibration measurement in natural work settings. Preliminary results indicate that the developed device could be used for health and safety studies, evaluation of protective equipment, and ongoing monitoring in a natural working environment, and in this way may lead to more effective prevention and management of the risks associated with exposure to workplace vibrations.
NASA Astrophysics Data System (ADS)
Chong, C.; Kim, E.; Charalampidis, E. G.; Kim, H.; Li, F.; Kevrekidis, P. G.; Lydon, J.; Daraio, C.; Yang, J.
2016-05-01
This article explores the excitation of different vibrational states in a spatially extended dynamical system through theory and experiment. As a prototypical example, we consider a one-dimensional packing of spherical particles (a so-called granular chain) that is subject to harmonic boundary excitation. The combination of the multimodal nature of the system and the strong coupling between the particles due to the nonlinear Hertzian contact force leads to broad regions in frequency where different vibrational states are possible. In certain parametric regions, we demonstrate that the nonlinear Schrödinger equation predicts the corresponding modes fairly well. The electromechanical model we apply predicts accurately the conversion from the obtained mechanical energy to the electrical energy observed in experiments.
NASA Astrophysics Data System (ADS)
Kim, In-Ho; Jang, Seon-Jun; Jung, Hyung-Jo
2013-07-01
In this paper, an innovative strategy for improving the performance of a recently developed rotational energy harvester is proposed. Its performance can be considerably enhanced by replacing the electromagnetic induction part, consisting of moving permanent magnets and a fixed solenoid coil, with a moving mass and a rotational generator (i.e., an electric motor). The proposed system is easily tuned to the natural frequency of a target structure using the position change of a proof mass. Owing to the high efficiency of the rotational generator, the device can more effectively harness electrical energy from the wind-induced vibration of a stay cable. Also, this new configuration makes the device more compact and geometrically tunable. In order to validate the effectiveness of the new configuration, a series of laboratory and field tests are carried out with the prototype of the proposed device, which is designed and fabricated based on the dynamic characteristics of the vibration of a stay cable installed in an in-service cable-stayed bridge. From the field test, it is observed that the normalized output power of the proposed system is 35.67 mW (m s-2)-2, while that of the original device is just 5.47 mW (m s-2)-2. These results show that the proposed device generates much more electrical energy than the original device. Moreover, it is verified that the proposed device can generate sufficient electricity to power a wireless sensor node placed on a cable under gentle-moderate wind conditions.
The benefits of noise and nonlinearity: Extracting energy from random vibrations
NASA Astrophysics Data System (ADS)
Gammaitoni, Luca; Neri, Igor; Vocca, Helios
2010-10-01
Nonlinear behavior is the ordinary feature of the vast majority of dynamical systems and noise is commonly present in any finite temperature physical and chemical system. In this article we briefly review the potentially beneficial outcome of the interplay of noise and nonlinearity by addressing the novel field of vibration energy harvesting. The role of nonlinearity in a piezoelectric harvester oscillator dynamics is modeled with nonlinear stochastic differential equation.
Interplay between vibrational energy transfer and excited state deactivation in DNA components.
West, Brantley A; Womick, Jordan M; Moran, Andrew M
2013-07-25
Femtosecond laser spectroscopies are used to examine a thymine family of systems chosen to expose the interplay between excited state deactivation and two distinct vibrational energy transfer (VET) pathways: (i) VET from the base to the deoxyribose ring; (ii) VET between neighboring units in a dinucleotide. We find that relaxation in the ground electronic state accelerates markedly as the molecular sizes increase from the nucleobase to the dinucleotide. This behavior directly reflects growth in the density of vibrational quantum states on the substituent of the base. Excited state lifetimes are studied at temperatures ranging from 100 to 300 K to characterize the thermal fluctuations that connect the Franck-Condon geometries and the conical intersections leading back to the ground state. An Arrhenius analysis yields an approximate excited state energy barrier of 13 meV in the thymine dinucleotide. In addition, we find that the transfer of vibrational energy from the base to the substituent suppresses thermal fluctuations across this energy barrier. The possibility that the solvent viscosity imposes friction on the reaction coordinate is examined by comparing thymine and adenine systems. Experiments suggest that the solvent viscosity has little effect on barrier crossing dynamics in thymine because the conical intersection is accessed through relatively small out-of-plane atomic displacements. Overall, we conclude that the transfer of vibrational quanta from thymine to the deoxyribose ring couples significantly to the internal conversion rate, whereas the neighboring unit in the dinucleotide serves as a secondary heat bath. In natural DNA, it follows that (local) thermal fluctuations in the geometries of subunits involving the base and deoxyribose ring are most important to this subpicosecond relaxation process.
Alkaline fuel cells for prime power and energy storage
NASA Astrophysics Data System (ADS)
Stedman, J. K.
Alkaline fuel cell technology and its application to future space missions requiring high power and energy storage are discussed. Energy densities exceeding 100 watthours per pound and power densities approaching 0.5 pounds per kilowatt are calculated for advanced systems. Materials research to allow reversible operation of cells for energy storage and higher temperature operation for peaking power is warranted.
NASA Astrophysics Data System (ADS)
Yoo, Ji Ho; Köckert, Hansjochen; Mullaney, John C.; Stephens, Susanna L.; Evans, Corey J.; Walker, Nicholas R.; Le Roy, Robert. J.
2016-12-01
Pure rotational spectra of PbI and InI are interpreted to yield a full analytic potential energy function for each molecule. Rotational spectra for PbI have been retrieved from literature sources to perform the analysis. Rotational transition frequencies for excited vibrational states of InI (0 < v < 11) are measured during this work. Ignoring hyperfine splittings, Bv and Dv values are used to generate a set of "synthetic" pure R (0) transitions for each vibrational level. These are then fitted to an "Expanded Morse Oscillator" (EMO) potential using the direct-potential-fit program, dPOTFIT. The well-depth parameter, De , is fixed at a literature value, while values of the equilibrium distance re and EMO exponent-coefficient expansion (potential-shape) parameters are determined from the fits. Comparison with potential functions determined after including older mid-IR and visible electronic transition data shows that our analysis of the pure microwave data alone yields potential energy functions that accurately predict (to better than 1%) the overtone vibrational energies far beyond the range spanned by the levels for which the microwave data is available.
Anaerobic power in road cyclists is improved after 10 weeks of whole-body vibration training.
Oosthuyse, Tanja; Viedge, Alison; McVeigh, Joanne; Avidon, Ingrid
2013-02-01
Whole-body vibration (WBV) training has previously improved muscle power in various athletic groups requiring explosive muscle contractions. To evaluate the benefit of including WBV as a training adjunct for improving aerobic and anaerobic cycling performance, road cyclists (n = 9) performed 3 weekly, 10-minute sessions of intermittent WBV on synchronous vertical plates (30 Hz) while standing in a static posture. A control group of cyclists (n = 8) received no WBV training. Before and after the 10-week intervention period, lean body mass (LBM), cycling aerobic peak power (Wmax), 4 mM lactate concentration (OBLA), VO2peak, and Wingate anaerobic peak and mean power output were determined. The WBV group successfully completed all WBV sessions but reported a significant 30% decrease in the weekly cycling training time (pre: 9.4 ± 3.3 h·wk(-1); post: 6.7 ± 3.7 h·wk(-1); p = 0.01) that resulted in a 6% decrease in VO2peak and a 4% decrease in OBLA. The control group reported a nonsignificant 6% decrease in cycling training volume (pre: 9.5 ± 3.6 h·wk(-1); 8.6 ± 2.9 h·wk(-1); p = 0.13), and all measured variables were maintained. Despite the evidence of detraining in the WBV group, Wmax was maintained (pre: 258 ± 53 W; post: 254 ± 57 W; p = 0.43). Furthermore, Wingate peak power increased by 6% (668 ± 189 to 708 ± 220 W; p = 0.055), and Wingate mean power increased by 2% (553 ± 157 to 565 ± 157 W; p = 0.006) in the WBV group from preintervention to postintervention, respectively, without any change to LBM. The WBV training is an attractive training supplement for improving anaerobic power without increasing muscle mass in road cyclists.
Energy Flux in the Cochlea: Evidence Against Power Amplification of the Traveling Wave.
van der Heijden, Marcel; Versteegh, Corstiaen P C
2015-10-01
Traveling waves in the inner ear exhibit an amplitude peak that shifts with frequency. The peaking is commonly believed to rely on motile processes that amplify the wave by inserting energy. We recorded the vibrations at adjacent positions on the basilar membrane in sensitive gerbil cochleae and tested the putative power amplification in two ways. First, we determined the energy flux of the traveling wave at its peak and compared it to the acoustic power entering the ear, thereby obtaining the net cochlear power gain. For soft sounds, the energy flux at the peak was 1 ± 0.6 dB less than the middle ear input power. For more intense sounds, increasingly smaller fractions of the acoustic power actually reached the peak region. Thus, we found no net power amplification of soft sounds and a strong net attenuation of intense sounds. Second, we analyzed local wave propagation on the basilar membrane. We found that the waves slowed down abruptly when approaching their peak, causing an energy densification that quantitatively matched the amplitude peaking, similar to the growth of sea waves approaching the beach. Thus, we found no local power amplification of soft sounds and strong local attenuation of intense sounds. The most parsimonious interpretation of these findings is that cochlear sensitivity is not realized by amplifying acoustic energy, but by spatially focusing it, and that dynamic compression is realized by adjusting the amount of dissipation to sound intensity.
Performance Studies of the Vibration Wire Monitor on the Test Stand with Low Energy Electron Beam
NASA Astrophysics Data System (ADS)
Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu
In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic
Non-classicality of the molecular vibrations assisting exciton energy transfer at room temperature
O’Reilly, Edward J.; Olaya-Castro, Alexandra
2014-01-01
Advancing the debate on quantum effects in light-initiated reactions in biology requires clear identification of non-classical features that these processes can exhibit and utilize. Here we show that in prototype dimers present in a variety of photosynthetic antennae, efficient vibration-assisted energy transfer in the sub-picosecond timescale and at room temperature can manifest and benefit from non-classical fluctuations of collective pigment motions. Non-classicality of initially thermalized vibrations is induced via coherent exciton–vibration interactions and is unambiguously indicated by negativities in the phase–space quasi-probability distribution of the effective collective mode coupled to the electronic dynamics. These quantum effects can be prompted upon incoherent input of excitation. Our results therefore suggest that investigation of the non-classical properties of vibrational motions assisting excitation and charge transport, photoreception and chemical sensing processes could be a touchstone for revealing a role for non-trivial quantum phenomena in biology. PMID:24402469
NASA Astrophysics Data System (ADS)
Emdadul Hoque, Md.; Mizuno, Takeshi; Ishino, Yuji; Takasaki, Masaya
2010-08-01
This paper presents a six-degree-of-freedom hybrid vibration isolation system integrated with an active negative suspension, an active-passive positive suspension and a passive weight support mechanism. The aim of the research consists in maximizing the system and control performances, and minimizing the system development and maintenance costs. The vibration isolation system is, fundamentally, developed by connecting an active negative suspension realized by zero-power control in series with an active-passive positive suspension. The system could effectively isolate ground vibrations in addition to suppress the effect of on-board generated direct disturbances of the six-axis motions, associated with vertical and horizontal directions. The system is further reinforced by introducing a passive weight support mechanism in parallel with the basic system. The modified system with zero-power control allows simplified design of the isolation table without power consumption. It also offers enhanced performance on direct disturbance suppression and large payload supporting capabilities, without degrading transmissibility characteristics. A mathematical model of the system is presented and, therefore, analyzed to demonstrate that zero-compliance to direct disturbance could be generated by the developed system. Experimental demonstrations validate the proposed concept that exhibits high stiffness of the isolation table to static and dynamic direct disturbances, and good transmissibility characteristics against ground vibration. Further improvements of the vibration isolation system and the control system are discussed as well.
Development and modelisation of a hydro-power conversion system based on vortex induced vibration
NASA Astrophysics Data System (ADS)
Lefebure, David; Dellinger, Nicolas; François, Pierre; Mosé, Robert
2016-11-01
The Vortex Induced Vibration (VIV) phenomenon leads to mechanical issues concerning bluff bodies immerged in fluid flows and have therefore been studied by numerous authors. Moreover, an increasing demand for energy implies the development of alternative, complementary and renewable energy solutions. The main idea of EauVIV project consists in the use of VIV rather than its deletion. When rounded objects are immerged in a fluid flow, vortices are formed and shed on their downstream side, creating a pressure imbalance resulting in an oscillatory lift. A convertor modulus consists of an elastically mounted, rigid cylinder on end-springs, undergoing flow- induced motion when exposed to transverse fluid-flow. These vortices induce cyclic lift forces in opposite directions on the circular bar and cause the cylinder to vibrate up and down. An experimental prototype was developed and tested in a free-surface water channel and is already able to recover energy from free-stream velocity between 0.5 and 1 m.s -1. However, the large number of parameters (stiffness, damping coefficient, velocity of fluid flow, etc.) associated with its performances requires optimization and we choose to develop a complete tridimensionnal numerical model solution. A 3D numerical model has been developed in order to represent the real system behavior and improve it through, for example, the addition of parallel cylinders. The numerical model build up was carried out in three phases. The first phase consists in establishing a 2D model to choose the turbulence model and quantify the dependence of the oscillations amplitudes on the mesh size. The second corresponds to a 3D simulation with cylinder at rest in first time and with vertical oscillation in a second time. The third and final phase consists in a comparison between the experimental system dynamic behavior and its numerical model.
NASA Astrophysics Data System (ADS)
Strozzi, Matteo; Smirnov, Valeri V.; Manevitch, Leonid I.; Milani, Massimo; Pellicano, Francesco
2016-10-01
In this paper, the nonlinear vibrations and energy exchange of single-walled carbon nanotubes (SWNTs) are studied. The Sanders-Koiter theory is applied to model the nonlinear dynamics of the system in the case of finite amplitude of vibration. The SWNT deformation is described in terms of longitudinal, circumferential and radial displacement fields. Simply supported, clamped and free boundary conditions are considered. The circumferential flexural modes (CFMs) are investigated. Two different approaches based on numerical and analytical models are compared. In the numerical model, an energy method based on the Lagrange equations is used to reduce the nonlinear partial differential equations of motion to a set of nonlinear ordinary differential equations, which is solved by using the implicit Runge-Kutta numerical method. In the analytical model, a reduced form of the Sanders-Koiter theory assuming small circumferential and tangential shear deformations is used to get the nonlinear ordinary differential equations of motion, which are solved by using the multiple scales analytical method. The transition from energy beating to energy localization in the nonlinear field is studied. The effect of the aspect ratio on the analytical and numerical values of the nonlinear energy localization threshold for different boundary conditions is investigated. Time evolution of the total energy distribution along the axis of a simply supported SWNT
Vibration transmission through periodic structures using a mobility power flow approach
NASA Technical Reports Server (NTRS)
Cuschieri, J. M.
1990-01-01
The transmission of vibrational power (time averaged) through multiple coupled (periodic) structures is examined. The analysis is performed in the frequency domain and the coupling between the sub-elements of the periodic structure is expressed in terms of structural mobility functions for the junction points and between the junction points of the sub-elements. Equal length spans between stiffeners or supports of the periodic structure are considered. Through the use of the mobility power flow approach, the influence of sub-element and junction parameters, including damping at the joints, can be investigated. The results from the analysis can be in the form of either structural intensity or alternatively structural power content for each of the sub-elements. The examples discussed are for a thin, perfectly periodic beam with a finite number of spans with different types of stiffeners and/or supports between the spans. The excitation of the structure is by a point load located midway along the first span.
Scavenging vibration energy from seismically isolated bridges using an electromagnetic harvester
NASA Astrophysics Data System (ADS)
Lu, Qiuchen; Loong, Chengning; Chang, Chih-Chen; Dimitrakopoulos, Elias G.
2014-04-01
The increasing worldwide efforts in securing renewable energy sources increase incentive for civil engineers to investigate whether the kinetic energy associated with the vibration of larger-scale structures can be harvested. Such a research remains challenging and incomplete despite that hundreds of related articles have been published in the last decade. Base isolation is one of the most popular means of protecting a civil engineering structure against earthquake forces. Seismic isolation hinges on the decoupling of the structure from the shaking ground, hence protecting the structure from stress and damage during an earthquake excitation. The low stiffness isolator inserted between the structure and the ground dominates the response leading to a structural system of longer vibration period. As a consequence of this period shift, the spectral acceleration is reduced, but higher response displacements are produced. To mitigate this side effect, usually isolators are combined with the use of additional energy dissipation. In this study, the feasibility of scavenging the need-to-be dissipated energy from the isolator installed in a seismically isolated bridge using an electromagnetic (EM) energy harvester is investigated. The EM energy harvester consists of an energy harvesting circuit and a capacitor for energy storage. A mathematical model for this proposed EM energy harvester is developed and implemented on an idealized base-isolated single-degree-of-freedom system. The effect of having this EM energy harvester on the performance of this seismic isolated system is analyzed and discussed. The potential of installing such an EM energy harvester on a seismically isolated bridge is also addressed.
Koput, Jacek
2015-06-30
The accurate ground-state potential energy function of imidogen, NH, has been determined from ab initio calculations using the multireference averaged coupled-pair functional (MR-ACPF) method in conjunction with the correlation-consistent core-valence basis sets up to octuple-zeta quality. The importance of several effects, including electron correlation beyond the MR-ACPF level of approximation, the scalar relativistic, adiabatic, and nonadiabatic corrections were discussed. Along with the large one-particle basis set, all of these effects were found to be crucial to attain "spectroscopic" accuracy of the theoretical predictions of vibration-rotation energy levels of NH.
NASA Astrophysics Data System (ADS)
Lumentut, Mikail F.; Howard, Ian M.
2016-02-01
This paper focuses on the primary development of novel numerical and analytical techniques of the modal damped vibration energy harvesters with arbitrary proof mass offset. The key equations of electromechanical finite element discretisation using the extended Lagrangian principle are revealed and simplified to give matrix and scalar forms of the coupled system equations, indicating the most relevant numerical technique for the power harvester research. To evaluate the performance of the numerical study, the analytical closed-form boundary value equations have been developed using the extended Hamiltonian principle. The results from the electromechanical frequency response functions (EFRFs) derived from two theoretical studies show excellent agreement with experimental studies. The benefit of the numerical technique is in providing effective and quick predictions for analysing parametric designs and physical properties of piezoelectric materials. Although analytical technique provides a challenging process for analysing the complex smart structure, it shows complementary study for validating the numerical technique.
Energy: Add Power to Your Collection.
ERIC Educational Resources Information Center
Rholes, Julia M.
1981-01-01
An annotated bibliography of 34 children's books on different types of energy at various reading levels includes general titles, as well as books on coal, geothermal energy, nuclear energy, ocean engineering, petroleum, solar energy, and wind energy. (CHC)
NASA Astrophysics Data System (ADS)
Pfeiffer, Florian; Rauhut, Guntram; Feller, David; Peterson, Kirk A.
2013-01-01
Anharmonic zero point vibrational energies (ZPVEs) calculated using both conventional CCSD(T) and MP2 in combination with vibrational second-order perturbation theory (VPT2) are compared to explicitly correlated CCSD(T)-F12 and MP2-F12 results that utilize vibrational configuration interaction (VCI) theory for 26 molecules of varying size. Sequences of correlation consistent basis sets are used throughout. It is found that the explicitly correlated methods yield results close to the basis set limit even with double-zeta quality basis sets. In particular, the anharmonic contributions to the ZPVE are accurately recovered at just the MP2 (or MP2-F12) level of theory. Somewhat surprisingly, the best vibrational CI results agreed with the VPT2 values with a mean unsigned deviation of just 0.09 kJ/mol and a standard deviation of just 0.11 kJ/mol. The largest difference was observed for C4H4O (0.34 kJ/mol). A simplified version of the vibrational CI procedure that limited the modal expansion to at most 2-mode coupling yielded anharmonic corrections generally within about 0.1 kJ/mol of the full 3- or 4-mode results, except in the cases of C3H8 and C4H4O where the contributions were underestimated by 1.3 and 0.8 kJ/mol, respectively (34% and 40%, respectively). For the molecules considered in this work, accurate anharmonic ZPVEs are most economically obtained by combining CCSD(T)-F12a/cc-pVDZ-F12 harmonic frequencies with either MP2/aug-cc-pVTZ/VPT2 or MP2-F12/cc-pVDZ-F12/VCI anharmonic corrections.
Feasibility of Self Powered Actuation for Flow, Separation and Vibration Control
NASA Technical Reports Server (NTRS)
Shyam, Vikram; Bak, Dillon; Izadnegahdar, Alain
2015-01-01
A gas turbine engine is anywhere from 40-50% efficient. A large amount of energy is wasted as heat. Some of this heat is recoverable through the use of energy harvesting and can be used for powering on-board systems or for storing energy in batteries to replace auxiliary power units (APUs). As hybrid electric aircraft become more common, the use of energy harvesting will see increasingly more benefit and become commonplace in gas turbine engines. For electric aircraft with motors, TEGs would be beneficial for reclaiming waste heat from electric motors. The primary focus of this work was to evaluate the feasibility of harvesting energy from the hot section of a gas turbine engine (for a single aisle Boeing 737 thrust class) using thermoelectric generators (TEGs). The resulting heat could be used to power on-board actuation mechanisms such as plasma actuators and piezoelectric actuators. The work is a result of a two year NASA Center Innovation Fund from 2009 to 2011. The trade-off between thermoelectric harvesting and blade surface temperature were studied to ensure that blade durability is not adversely impacted by embedding a low thermal conductivity TEG. Calculations show that.5-10 Watts can be harvested per blade depending on flow conditions and on the thermoelectric material chosen. BiTe and SiGe were used for this analysis and future thermoelectric generators or multiferroic alloys could considerably improve power output.
Fujisaki, Hiroshi; Straub, John E
2007-10-18
With use of a time-dependent perturbation theory, vibrational energy relaxation (VER) of isotopically labeled amide I modes in cytochrome c solvated with water is investigated. Contributions to the VER are decomposed into two contributions from the protein and water. The VER pathways are visualized by using radial and angular excitation functions for resonant normal modes. Key differences of VER among different amide I modes are demonstrated, leading to a detailed picture of the spatial anisotropy of the VER. The results support the experimental observation that amide I modes in proteins relax with subpicosecond time scales, while the relaxation mechanism turns out to be sensitive to the environment of the amide I mode.
Electric power processing, distribution, management and energy storage
NASA Technical Reports Server (NTRS)
Giudici, R. J.
1980-01-01
Power distribution subsystems are required for three elements of the SPS program: (1) orbiting satellite, (2) ground rectenna, and (3) Electric Orbiting Transfer Vehicle (EOTV). Power distribution subsystems receive electrical power from the energy conversion subsystem and provide the power busses rotary power transfer devices, switchgear, power processing, energy storage, and power management required to deliver control, high voltage plasma interactions, electric thruster interactions, and spacecraft charging of the SPS and the EOTV are also included as part of the power distribution subsystem design.
Power flow as a complement to statistical energy analysis and finite element analysis
NASA Technical Reports Server (NTRS)
Cuschieri, J. M.
1987-01-01
Present methods of analysis of the structural response and the structure-borne transmission of vibrational energy use either finite element (FE) techniques or statistical energy analysis (SEA) methods. The FE methods are a very useful tool at low frequencies where the number of resonances involved in the analysis is rather small. On the other hand SEA methods can predict with acceptable accuracy the response and energy transmission between coupled structures at relatively high frequencies where the structural modal density is high and a statistical approach is the appropriate solution. In the mid-frequency range, a relatively large number of resonances exist which make finite element method too costly. On the other hand SEA methods can only predict an average level form. In this mid-frequency range a possible alternative is to use power flow techniques, where the input and flow of vibrational energy to excited and coupled structural components can be expressed in terms of input and transfer mobilities. This power flow technique can be extended from low to high frequencies and this can be integrated with established FE models at low frequencies and SEA models at high frequencies to form a verification of the method. This method of structural analysis using power flo and mobility methods, and its integration with SEA and FE analysis is applied to the case of two thin beams joined together at right angles.
NASA Astrophysics Data System (ADS)
Faria, Cassio T.; Inman, Daniel J.
2014-04-01
When a mechanical and/or structural component is immersed in a fluid and it vibrates, the reasonable assumption is that part of the energy is transmitted to the adjacent media. For some engineering applications the energy transport between these two domains, i.e., structure and fluid, plays a central role. The work presented in this paper is focused on discussing the energy transport in beam-like structures as they can be used to represent flexible swimmers (fish-like pulsating mechanisms) in their simplest form. In order to expose the role of each of the fluid and beam properties effecting the energy transfer process, a simplified analytical fluid-structure interaction (FSI) model is derived. After analysis of the resulting coupled-systems' damping coefficient, a new energy transport component is added to the initial Euler-Bernoulli beam equation; a term associated with diffusion (fluid viscosity). In addition our modeling results in an added mass term, a characteristic consistent with previous literature. While deriving the model, an important assumption is made: beam mode shapes are not significantly affected by the domains' interaction. This hypothesis is experimentally tested in two different fluid media and confirmed to be reasonable for the first three vibration mode shapes.
Excitation of vibrational quanta in furfural by intermediate-energy electrons.
Jones, D B; Neves, R F C; Lopes, M C A; da Costa, R F; Varella, M T do N; Bettega, M H F; Lima, M A P; García, G; Blanco, F; Brunger, M J
2015-12-14
We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.
Excitation of vibrational quanta in furfural by intermediate-energy electrons
Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; Costa, R. F. da; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; García, G.; and others
2015-12-14
We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.
Semi-active controller design for vibration suppression and energy harvesting via LMI approach
NASA Astrophysics Data System (ADS)
Liu, Yilun; Lin, Chi-Chang; Zuo, Lei
2014-04-01
The vibration control plays an important role in energy harvesting systems. Compared to the active control, semi-active control is a more preferred alternative for practical use. Many different semi-active control strategies have been developed, among which LQ-clip, Skyhook and model predictive control are the most popular strategies in literatures. In this paper, a different control strategy that designs semi-active controller via LMI approach is proposed. Different from clipping the control input after controller construction like most existing control methods, the proposed method fulfills the semi-active control input feasibility constraints before the controller construction. The methodology is developed through LMI approach which leads to a stabilizing linear controller to ensure semi-active constraint and the pre-designed performance. An illustrative example, vibration control system of a tall building, is presented to show the efficiency of the method and validate the new approach.
APPLICATION OF STATISTICAL ENERGY ANALYSIS TO VIBRATIONS OF MULTI-PANEL STRUCTURES.
cylindrical shell are compared with predictions obtained from statistical energy analysis . Generally good agreement is observed. The flow of mechanical...the coefficients of proportionality between power flow and average modal energy difference, which one must know in order to apply statistical energy analysis . No
Model of a single mode energy harvester and properties for optimal power generation
NASA Astrophysics Data System (ADS)
Liao, Yabin; Sodano, Henry A.
2008-12-01
The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, the field of power harvesting has experienced significant growth due to the ever increasing desire to produce portable and wireless electronics with extended life. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of