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1

PIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGY  

E-print Network

PIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGY PIEZOELECTRIC POWER SCAVENGING OFPIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGYMECHANICAL VIBRATION ENERGY CE 511- Structural

Ervin, Elizabeth K.

2

Power Processing Circuits for Piezoelectric Vibration-Based Energy Harvesters  

Microsoft Academic Search

The behavior of a piezoelectric vibration-driven energy harvester with different power processing circuits is evaluated. Two load types are considered: a resistive load and an ac-dc rectifier load. An optimal resistive and optimal dc-voltage load for the harvester is analytically calculated. The difference between the optimal output power flow from the harvester to both load circuits depends on the coupling

R. D'hulst; T. Sterken; R. Puers; G. Deconinck; J. Driesen

2010-01-01

3

A micropower programmable DSP powered using a MEMS-based vibration-to-electric energy converter  

Microsoft Academic Search

An ultra-low-power programmable DSP for sensor applications enables systems to be powered by ambient vibration. The three-chip system consists of a MEMS transducer that converts vibration to a voltage delivered to a conversion IC. The conversion IC creates a stable power supply that provides energy to the sensor DSP load. The system exploits ambient mechanical vibration as its energy source

R. Amirtharajah; S. Meninger; J. O. Mur-Miranda; A. Chandrakasan; J. Lang

2000-01-01

4

Improving power output for vibration-based energy scavengers  

Microsoft Academic Search

Pervasive networks of wireless sensor and communication nodes have the potential to significantly impact society and create large market opportunities. For such networks to achieve their full potential, however, we must develop practical solutions for self-powering these autonomous electronic devices. We've modeled, designed, and built small cantilever-based devices using piezoelectric materials that can scavenge power from low-level ambient vibration sources.

Shad Roundy; Eli S. Leland; Jessy Baker; Eric Carleton; Elizabeth K. Reilly; Elaine Lai; Brian Otis; Jan M. Rabaey; Paul K. Wright; V. Sundararajan

2005-01-01

5

A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data  

NASA Astrophysics Data System (ADS)

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.

Beeby, Stephen P.; Wang, Leran; Zhu, Dibin; Weddell, Alex S.; Merrett, Geoff V.; Stark, Bernard; Szarka, Gyorgy; Al-Hashimi, Bashir M.

2013-07-01

6

Vibration energy harvesting is an attractive technique for the potential powering of wireless sensors and low power devices. While the technique can be employed to  

E-print Network

ABSTRACT Vibration energy harvesting is an attractive technique for the potential powering vibrations and vibrating structures, a general requirement independent of the mechanical to electrical energy transfer mechanism is that the vibration energy harvesting device operate in resonance at the excitation

Fisher, Frank

7

Powering pacemakers from heartbeat vibrations using linear and nonlinear energy harvesters  

NASA Astrophysics Data System (ADS)

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.

Amin Karami, M.; Inman, Daniel J.

2012-01-01

8

Scaling and power density metrics of electromagnetic vibration energy harvesting devices  

NASA Astrophysics Data System (ADS)

A review of the vibration energy harvesting literature has been undertaken with the goal of establishing scaling laws for experimentally demonstrated harvesting devices based on electromagnetic transduction. Power density metrics are examined with respect to scaling length, mass, frequency and drive acceleration. Continuous improvements in demonstrated power density of harvesting devices over the past decade are noted. Scaling laws are developed from observations that appear to suggest an upper limit to the power density achievable with current harvesting techniques.

Moss, Scott D.; Payne, Owen R.; Hart, Genevieve A.; Ung, Chandarin

2015-02-01

9

A Vibration-Based MEMS Piezoelectric Energy Harvester and Power Conditioning Circuit  

PubMed Central

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 ?W, or a power density of 5.19 ?W·mm?3·g?2 with an optimal resistive load of 220 k? 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

Yu, Hua; Zhou, Jielin; Deng, Licheng; Wen, Zhiyu

2014-01-01

10

A vibration-based MEMS piezoelectric energy harvester and power conditioning circuit.  

PubMed

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 ?W, or a power density of 5.19 ?W?mm-3?g-2 with an optimal resistive load of 220 k? 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

Yu, Hua; Zhou, Jielin; Deng, Licheng; Wen, Zhiyu

2014-01-01

11

Self-powered autonomous wireless sensor node using vibration energy harvesting  

NASA Astrophysics Data System (ADS)

This paper reports the development and implementation of an energy aware autonomous wireless condition monitoring sensor system (ACMS) powered by ambient vibrations. An electromagnetic (EM) generator has been designed to harvest sufficient energy to power a radio-frequency (RF) linked accelerometer-based sensor system. The ACMS is energy aware and will adjust the measurement/transmit duty cycle according to the available energy; this is typically every 3 s at 0.6 m s-2rms acceleration and can be as low as 0.2 m s-2rms with a duty cycle around 12 min. The EM generator has a volume of only 150 mm3 producing an average power of 58 µW at 0.6 m s-2rms acceleration at a frequency of 52 Hz. In addition, a voltage multiplier circuit is shown to increase the electrical damping compared to a purely resistive load; this allows for an average power of 120 µW to be generated at 1.7 m s-2rms acceleration. The ACMS has been successfully demonstrated on an industrial air compressor and an office air conditioning unit, continuously monitoring vibration levels and thereby simulating a typical condition monitoring application.

Torah, R.; Glynne-Jones, P.; Tudor, M.; O'Donnell, T.; Roy, S.; Beeby, S.

2008-12-01

12

Electromagnetic Energy Harvesting Circuit With Feedforward and Feedback DC–DC PWM Boost Converter for Vibration Power Generator System  

Microsoft Academic Search

This paper presents an integrated vibration power generator system. The system consists of a mini electromagnetic vibration power generator and a highly efficient energy harvesting circuit implemented on a minute printed circuit board and a 0.35-mum CMOS integrated chip. By introducing a feedback control into the dc-dc pulsewidth modulation (PWM) boost converter with feedforward control, the energy harvesting circuit can

Xinping Cao; Wen-Jen Chiang; Ya-Chin King; Yi-Kuen Lee

2007-01-01

13

Multi-modal vibration based MEMS energy harvesters for ultra-low power wireless functional nodes  

NASA Astrophysics Data System (ADS)

The aim of this contribution is to report and discuss a preliminary study and rough optimization of a novel concept of MEMS device for vibration energy harvesting, based on a multi-modal dynamic behavior. The circular-shaped device features Four-Leaf Clover-like (FLC) double spring-mass cascaded systems, kept constrained to the surrounding frame by means of four straight beams. The combination of flexural bending behavior of the slender beams plus deformable parts of the petals enable to populate the desired vibration frequency range with a number of resonant modes, and improve the energy conversion capability of the micro-transducer. The harvester device, conceived for piezoelectric mechanical into electric energy conversion, is intended to sense environmental vibrations and, thereby, its geometry is optimized to have a large concentration of resonant modes in a frequency range below 5-10 kHz. The results of FEM (Finite Element Method) based analysis performed in ANSYSTM Workbench are reported, both concerning modal and harmonic response, providing important indications related to the device geometry optimization. The analysis reported in this work is limited to the sole mechanical modeling of the proposed MEMS harvester device concept. Future developments of the study will encompass the inclusion of piezoelectric conversion in the FEM simulations, in order to have indications of the actual power levels achievable with the proposed harvester concept. Furthermore, the results of the FEM studies here discussed, will be validated against experimental data, as soon as the MEMS resonator specimens, currently under fabrication, are ready for testing.

Iannacci, J.; Gottardi, M.; Serra, E.; Di Criscienzo, R.; Borrielli, A.; Bonaldi, M.

2013-05-01

14

Downhole vibration sensing by vibration energy harvesting  

E-print Network

This thesis outlines the design of a prototype electromagnetic induction vibration energy harvesting device for use in a downhole environment. First order models of the necessary components for a generic vibration energy ...

Trimble, A. Zachary

2007-01-01

15

Power Electronic Devices for Damping Torsional Vibrations  

Microsoft Academic Search

Torsional vibrations and resonance problems with synchronous machines are most frequently encountered in rotor systems with long shafts and large inertias constituting a weakly damped mechanical resonator which exhibits a low resonance frequency. It is impossible to obtain a effective mechanical damping for these torsional vibrations, but by using a power electronics device and an inductive or capacitive energy storage

A. M. Miri; T. Zöller; T. Leibfried

16

Vibration Testing of Stirling Power Convertors  

NASA Technical Reports Server (NTRS)

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 to supply on- board electric spacecraft power for future NASA Deep-Space Missions, performing as an attractive alternative to Radioisotope Thermoelectric Generators (RTG). Usage of the Stirling technology is also being considered as the electric power source for future Mars rovers, whose mission profiles may exclude the use of photovoltaic power systems (such as exploring at high Martian latitudes or for missions of lengthy durations). GRC s Thermo-Mechanical Systems Branch (5490) provides Stirling technology expertise under a Space Act Agreement with the DOE. Additional vibration testing, by GRC s Structural Systems Dynamics Branch (7733, is planned to continue to demonstrate the Stirling power system s vibration capability as its technology and flight system designs progress.

Hughes, Bill; Goodnight, Thomas; McNelis, Mark E.; Suarez, Vicente J.; Schreiber, Jeff; Samorezov, Sergey

2003-01-01

17

A Framework for Determining the Maximum Theoretical Power Output for a Given Vibration Energy  

NASA Astrophysics Data System (ADS)

This paper outlines a mathematical framework to determine the upper bound on extractable power as a function of the forcing vibrations. In addition to determining the upper bound on power output, the method described provides insight into the dynamic transducer forces required to attain the upper bound. This relationship, between input vibration parameters and transducer force gives a critical first step in determining the optimal transducer architecture for a given vibration input. The method developed is applied to two specific vibration inputs; a single sinusoid, and the sum of two sinusoids. For the single sinusoidal case, the optimal transducer force is found to be that produced by a linear spring, resonant with the input frequency, and a linear viscous damper, with matched impedance to the mechanical damper. The solution to this first case was previously known, but has been used here to validate the methodology. The resulting transducer force for the input described by a sum of two sinusoids is found to be inherently time dependent. This time dependency shows that an active system can outperform a passive system. Furthermore, the upper bound on power output is shown to be twice that obtainable from a linear harvester centred at the lower of the two frequencies.

Heit, J.; Roundy, S.

2014-11-01

18

Harvesting energy from non-ideal vibrations  

E-print Network

Energy harvesting has drawn significant interest for its potential to power autonomous low-power applications. Vibration energy harvesting is particularly well suited to industrial condition sensing, environmental monitoring ...

Chang, Samuel C

2013-01-01

19

Energy harvesting vibration sources for microsystems applications  

Microsoft Academic Search

This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric,

S P Beeby; M J Tudor; N M White

2006-01-01

20

Energy harvesting of gas pipeline vibration  

NASA Astrophysics Data System (ADS)

Pipelines conveying gas under pressure exhibit turbulence-induced vibrations. The current work is concerned with extracting useful power from pipelines operating well within their stability region. At such regions, the pipe vibrations exist in small magnitudes and are unlikely to cause structural failure, yet can be exploited to provide useful energy for low-power electronic devices. Accordingly, emphasis in the present work is placed on the development of an energy harvesting technique employing the omnipresent and inevitable flow-induced vibrations in gas pipelines.

Arafa, M.; Akl, W.; Majeed, M.; Al-Hussain, K.; Baz, A.

2010-04-01

21

A Linear Generator Powered from Bridge Vibrations for Wireless Sensors  

Microsoft Academic Search

A linear generator harvests which bridge vibration energy is used as the power source for a 3.3 V supply for the wireless sensor. Because of its ironless structure, the generator must be designed using the finite element method (FEM). The prime mover's mass and spring stiffness are analyzed with the vibration energy of the bridge. The linear generator's model is

Haodong Li; Pragasen Pillay

2007-01-01

22

Wireless Inductive Power Device Suppresses Blade Vibrations  

NASA Technical Reports Server (NTRS)

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 possible to moderate vibration on or in turbomachinery blades by providing 100 W of wireless electrical power and actuation control to thin, lightweight vibration-suppressing piezoelectric patches (eight actuation and eight sensor patches in this prototype, for a total of 16 channels) positioned strategically on the surface of, or within, titanium fan blades, or embedded in composite fan blades. This approach moves significantly closer to the ultimate integration of "active" vibration suppression technology into jet engines and other turbomachinery devices such as turbine electrical generators used in the power industry. The novel feature of this device is in its utilization of wireless technology to simultaneously sense and actively control vibration in rotating or stationary turbomachinery blades using piezoelectric patches. In the past, wireless technology was used solely for sensing and diagnostics. This technology, however, will accomplish much more, in terms of simultaneously sensing, suppressing blade vibration, and making it possible for detailed study of vibration impact in turbomachinery blades.

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

23

Energy scavenging from environmental vibration.  

SciTech Connect

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 fabricated device currently generates a peak power of 25.9{micro}W and an average power of 1.21{micro}W from an input acceleration of 9.8m/s{sup -} at 10Hz. The device operates over a frequency range of 23Hz. The internal volume of the generator is 1.2cm{sup 3}.

Galchev, Tzeno (University of Michigan); Apblett, Christopher Alan; Najafi, Khalil (University of Michigan)

2009-10-01

24

A Miniature Coupled Bistable Vibration Energy Harvester  

NASA Astrophysics Data System (ADS)

This paper reports the design and test of a miniature coupled bistable vibration energy harvester. Operation of a bistable structure largely depends on vibration amplitude rather than frequency, which makes it very promising for wideband vibration energy harvesting applications. A coupled bistable structure consists of a pair of mobile magnets that create two potential wells and thus the bistable phenomenon. It requires lower excitation to trigger bistable operation compared to conventional bistable structures. Based on previous research, this work focused on miniaturisation of the coupled bistable structure for energy harvesting application. The proposed bistable energy harvester is a combination of a Duffing's nonlinear structure and a linear assisting resonator. Experimental results show that the output spectrum of the miniature coupled bistable vibration energy harvester was the superposition of several spectra. It had a higher maximum output power and a much greater bandwidth compared to simply the Duffing's structure without the assisting resonator.

Zhu, D.; Arthur, D. C.; Beeby, S. P.

2014-11-01

25

An electromagnetic, vibration-powered generator for intelligent sensor systems  

Microsoft Academic Search

This paper describes the design of miniature generators capable of converting ambient vibration energy into electrical energy for use in powering intelligent sensor systems. Such a device acts as the power supply of a microsystem which can be used in inaccessible areas where wires can not be practically attached to provide power or transmit sensor data. Two prototypes of miniature

P. Glynne-Jones; M. J. Tudor; S. P. Beeby; N. M. White

2004-01-01

26

Vibration-to-electric energy conversion  

Microsoft Academic Search

A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) tech- nology. A low-power controller IC has been fabricated in a 0 6µm CMOS pro- cess and has been tested and

Scott Meninger; Jose Oscar Mur-Miranda; Rajeevan Amirtharajah; Anantha Chandrakasan; Jeffrey Lang

1999-01-01

27

Vibration harvesting in traffic tunnels to power wireless sensor nodes  

NASA Astrophysics Data System (ADS)

Monitoring the traffic and the structural health of traffic tunnels requires numerous sensors. Powering these remote and partially embedded sensors from ambient energies will reduce maintenance costs, and improve the sensor network performance. This work reports on vibration levels detected in railway and road tunnels as a potential energy source for embedded sensors. The measurement results showed that the vibrations at any location in the road tunnel and at the wall in the railway tunnel are too small for useful vibration harvesting. In contrast, the railway sleeper features usable vibrations and sufficient mounting space. For this application site, a robust piezoelectric vibration harvester was designed and equipped with a power interface circuit. Within the field test, it is demonstrated that sufficient energy is harvested to supply a microcontroller with a radio frequency (RF) interface.

Wischke, M.; Masur, M.; Kröner, M.; Woias, P.

2011-08-01

28

Vibration based energy harvesting using piezoelectric material  

Microsoft Academic Search

Energy harvesting has been around for centuries in the form of windmills, watermills and passive solar power systems. It is not only restricted to the natural resources but it has widen the tapping source to utilise the vibration which happen all around us. In the last decade, beam with piezoceramic patches have been used as a method to harverst energy.

M. N Fakhzan; Asan G. A. Muthalif

2011-01-01

29

Self-powered signal processing using vibration-based power generation  

Microsoft Academic Search

Low power design trends raise the possibility of using ambient energy to power future digital systems. A chip has been designed and tested to demonstrate the feasibility of operating a digital system from power generated by vibrations in its environment. A moving coil electromagnetic transducer was used as a power generator. Calculations show that power on the order of 400

Rajeevan Amirtharajah; Anantha P. Chandrakasan

1998-01-01

30

A vibration energy harvester using magnet/piezoelectric composite transducer  

NASA Astrophysics Data System (ADS)

In this research, a vibration energy harvester employing the magnet/piezoelectric composite transducer to convert mechanical vibration energy into electrical energy is presented. The electric output performance of a vibration energy harvester has been investigated. Compared to traditional magnetoelectric transducer, the proposed vibration energy harvester has some remarkable characteristic which do not need binder. The experimental results show that the presented vibration energy harvester can obtain an average power of 0.39 mW for an acceleration of 0.6g at frequency of 38 Hz. Remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a widely range of wireless sensors in wireless sensor network.

Qiu, Jing; Chen, Hengjia; Wen, Yumei; Li, Ping; Yang, Jin; Li, Wenli

2014-05-01

31

Vibrational power flow analysis of rods and beams. Thesis  

NASA Technical Reports Server (NTRS)

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.

Wohlever, James Christopher; Bernhard, R. J.

1988-01-01

32

Harvesting vibrational energy using material work functions.  

PubMed

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

Varpula, Aapo; Laakso, Sampo J; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

2014-01-01

33

Harvesting Vibrational Energy Using Material Work Functions  

PubMed Central

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

Varpula, Aapo; Laakso, Sampo J.; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

2014-01-01

34

Energy harvesting from wind-induced vibration of suspension bridges  

E-print Network

Recently, an extensive amount of research has been focused on energy harvesting from structural vibration sources for wireless self-powered microsystem applications. One method of energy harvesting is using electromagnetic ...

Shi, Miao, M. Eng. Massachusetts Institute of Technology

2013-01-01

35

Vibrational excitation energies from vibrational coupled cluster response theory  

NASA Astrophysics Data System (ADS)

Response theory in the context of vibrational coupled cluster (VCC) theory is introduced and used to obtain vibrational excitation energies. The relation to the vibrational configuration interaction (VCI) approach is described, and the increase in accuracy of VCC response energies relative to VCI energies is discussed theoretically in terms of a perturbational order expansion and demonstrated numerically. To illustrate the theory, a pilot implementation is used to obtain anharmonic vibrational frequencies for fundamental, first overtone and combination excitations of formaldehyde as well as for the fundamental transitions of ethylene.

Seidler, Peter; Christiansen, Ove

2007-05-01

36

Vibration characteristic of high power CO2 laser  

NASA Astrophysics Data System (ADS)

High power CO2 laser is widely used in various scientific, industrial and military applications. Vibration is a common phenomenon during laser working process, it will affect the working performance of high power CO2 laser, vibration must be strictly controlled in the condition where the laser pointing is required. This paper proposed a method to investigate the vibration characteristic of high power CO2 laser. An experiment device with vibration acceleration sensor was established to measure vibration signal of CO2 laser, the measured vibration signal was mathematically treated using space-frequency conversion, and then the vibration characteristic of high power CO2 laser can be obtained.

Zhang, Kuo

2015-02-01

37

Energy scavenging from low frequency vibrations  

NASA Astrophysics Data System (ADS)

The development of three energy conversion devices that are able to transform vibrations in their surroundings to electrical energy is discussed in this thesis. These energy harvesters are based upon a newly invented architecture called the Parametric Frequency Increased Generator (PFIG). The PFIG structure is designed to efficiently convert low frequency and non-periodic vibrations into electrical power. The three PFIG devices have a combined operating range covering two orders of magnitude in acceleration (0.54--19.6m/s 2) and a frequency range spanning up to 60Hz; making them some of the most versatile generators in existence. The PFIG utilizes a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromechanical scavenger. By up-converting the ambient vibration frequency to a higher internal operation frequency, the PFIG achieves better electromechanical coupling. The fixed internal displacement and dynamics of the PFIG allow it to operate more efficiently than resonant generators when the ambient vibration amplitude is higher than the internal displacement limit of the device. The PFIG structure is capable of efficiently converting mechanical vibrations with variable characteristics including amplitude and frequency, into electrical power. The first electromagnetic harvester can generate a peak power of 163microW and an average power of 13.6microW from an input acceleration of 9.8m/s 2 at 10Hz, and it can operate up to 60Hz. The internal volume of the generator is 2.12cm3 (3.75 including casing). It sets the state-of-the-art in efficiency in the <20Hz range. The volume figure of merit is 0.068%, which is a 10x improvement over other published works. It has a record high bandwidth figure of merit (0.375%). A second piezoelectric implementation generates 3.25microW of average power under the same excitation conditions, while the volume of the generator is halved (1.2cm3). A third PFIG was developed for critical infrastructure monitoring applications. It is used to harvest the very low-amplitude, low-frequency, and non-periodic vibrations present on bridges. The device generates 2.3microW of average power from an input acceleration of 0.54m/s2 at only 2Hz. The internal volume of the generator is 43cm3. It can operate over an unprecedentedly large acceleration (0.54--9.8m/s2) and frequency range (up to 30Hz) without any modifications or tuning.

Galchev, Tzeno V.

38

Design and performance of a microelectromagnetic vibration powered generator  

Microsoft Academic Search

In this paper we, report on the design, simulation and initial results of a microgenerator, which converts external vibrations into electrical energy. Power is generated by means of electromagnetic transduction with static magnets positioned either side of a moving coil located on a silicon structure designed to resonate laterally in the plane of the chip. The development and fabrication of

S. P. Beeby; M. J. Tudor; E. Koukharenko; N. M. White; T. O'Donnell; C. Saha; S. Kulkarni; S. Roy

2005-01-01

39

A MEMS vibration energy harvester for automotive applications  

NASA Astrophysics Data System (ADS)

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 ?W [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 ?W [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.

van Schaijk, R.; Elfrink, R.; Oudenhoven, J.; Pop, V.; Wang, Z.; Renaud, M.

2013-05-01

40

Modeling and design of a MEMS piezoelectric vibration energy harvester  

E-print Network

The modeling and design of MEMS-scale piezoelectric-based vibration energy harvesters (MPVEH) are presented. The work is motivated by the need for pervasive and limitless power for wireless sensor nodes that have application ...

Du Toit, Noël Eduard

2005-01-01

41

Electrostatic vibration-to-electric energy conversion  

E-print Network

Ultra-Low-Power electronics can perform useful functions with power levels as low as 170 nW. This makes them amenable to powering from ambient sources such as vibration. In this case, they can become autonomous. Motivated ...

Mur Miranda, José Oscar, 1972-

2004-01-01

42

Similarity and duality of electromagnetic and piezoelectric vibration energy harvesters  

NASA Astrophysics Data System (ADS)

A frequency analysis has been conducted to study vibration energy harvesting performance and characteristics of a single degree of freedom vibration energy harvester connected to a single load resistor based on the Laplace transfer method and physical models of a voltage source. The performance and characteristics of electromagnetic and piezoelectric harvesters have been analysed and compared. The main research outcome is the disclosure of similarity and duality of electromagnetic and piezoelectric harvesters for both the energy harvesting efficiency and the normalised resonant harvested power using only two dimensionless characteristic parameters: the normalised resistance and the normalised force factor. The dimensionless resonant harvested power and energy harvesting efficiency analysis allows for a parameter study and optimization of the ambient vibration energy harvesters from macro- to nano-scales and for evaluation of the vibration energy harvester performance regardless of the size and type.

Wang, Xu; John, Sabu; Watkins, Simon; Yu, Xinghuo; Xiao, Han; Liang, Xingyu; Wei, Haiqiao

2015-02-01

43

Vibrational structure theory: new vibrational wave function methods for calculation of anharmonic vibrational energies and vibrational contributions to molecular properties.  

PubMed

A number of recently developed theoretical methods for the calculation of vibrational energies and wave functions are reviewed. Methods for constructing the appropriate quantum mechanical Hamilton operator are briefly described before reviewing a particular branch of theoretical methods for solving the nuclear Schrödinger equation. The main focus is on wave function methods using the vibrational self-consistent field (VSCF) as starting point, and includes vibrational configuration interaction (VCI), vibrational Møller-Plesset (VMP) theory, and vibrational coupled cluster (VCC) theory. The convergence of the different methods towards the full vibrational configuration interaction (FVCI) result is discussed. Finally, newly developed vibrational response methods for calculation of vibrational contributions to properties, energies, and transition probabilities are discussed. PMID:17551617

Christiansen, Ove

2007-06-21

44

Evaluating vehicular-induced bridge vibrations for energy harvesting applications  

NASA Astrophysics Data System (ADS)

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.

Reichenbach, Matthew; Fasl, Jeremiah; Samaras, Vasilis A.; Wood, Sharon; Helwig, Todd; Lindenberg, Richard

2012-04-01

45

A vibration energy harvester using diamagnetic levitation  

NASA Astrophysics Data System (ADS)

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 ?W and at a frequency of 2.7 Hz, the harvester generated a power of 0.744 ?W 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.

Palagummi, S.; Yuan, F. G.

2013-04-01

46

A magnetically levitated vibration energy harvester  

NASA Astrophysics Data System (ADS)

In this paper a novel electromagnetic vibration type energy harvester that 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 thick cylindrical coils, placed in grooves which are engraved in the pyrolytic graphite plates, are used to convert the mechanical energy into electrical energy efficiently. The geometric configurations of the coils are selected based on the field distribution of the magnet to enhance the efficiency of the harvester. A thorough theoretical analysis is carried out to compare with experimental results. At an input power of 103.45 ?W and at a frequency of 2.7 Hz, the harvester generated a power of 0.74 ?W with a system efficiency of 0.72%. Both theoretical and experimental results show that this new energy harvesting system can capture low frequency broadband spectra.

Wang, X. Y.; Palagummi, S.; Liu, L.; Yuan, F. G.

2013-05-01

47

A comparison between several vibration-powered piezoelectric generators for standalone systems  

Microsoft Academic Search

This paper presents a comparison between four vibration-powered generators designed to power standalone systems, such as wireless transducers. Ambient vibrations are converted into electrical energy using piezoelectric materials. The originality of the proposed approaches is based on a particular processing of the voltage delivered by the piezoelectric material, which enhances the electromechanical conversion. The principle of each processing circuit is

E. Lefeuvre; A. Badel; C. Richard; L. Petit; D. Guyomar

2006-01-01

48

Vibration energy harvesting from random force and motion excitations  

NASA Astrophysics Data System (ADS)

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 on the parameters of the TMD subsystem if the ratio of electrical and mechanical damping is constant.

Tang, Xiudong; Zuo, Lei

2012-07-01

49

Microelectromechanical systems vibration powered electromagnetic generator for wireless sensor applications  

Microsoft Academic Search

This paper presents a silicon microgenerator, fabricated using standard silicon micromachining techniques, which converts\\u000a external ambient vibrations into electrical energy. Power is generated by an electromagnetic transduction mechanism with static\\u000a magnets positioned on either side of a moving coil, which is located on a silicon structure designed to resonate laterally\\u000a in the plane of the chip. The volume of this

E. Koukharenko; S. P. Beeby; M. J. Tudor; N. M. White; T. O’Donnell; C. Saha; S. Kulkarni; S. Roy

2006-01-01

50

A study of low level vibrations as a power source for wireless sensor nodes  

Microsoft Academic Search

Advances in low power VLSI design, along with the potentially low duty cycle of wireless sensor nodes open up the possibility of powering small wireless computing devices from scavenged ambient power. A broad review of potential power scavenging technologies and conventional energy sources is first presented. Low-level vibrations occurring in common household and office environments as a potential power source

Shad Roundy; Paul K. Wright; Jan M. Rabaey

2003-01-01

51

Adaptive Vibration Reduction System Shown to Effectively Eliminate Vibrations for the Stirling Radioisotope Power System  

NASA Technical Reports Server (NTRS)

Stirling Technology Company (STC), as part of a Small Business Innovation Research contract Phase II with the NASA Glenn Research Center at Lewis Field, is developing an Adaptive Vibration Reduction System (AVRS) that will effectively eliminate vibrations for the Stirling radioisotope power system. The AVRS will reduce vibration levels for two synchronized, opposed Stirling converters by a factor of 10 or more under normal operating conditions. Even more importantly, the AVRS will be adaptive and will be able to adjust to any changing converter conditions over the course of a mission. The Stirling converter is being developed by NASA and the Department of Energy (DOE) as a high-efficiency option for a radioisotope power system to provide onboard electric power for NASA deep space missions. The high Stirling efficiency of over 25 percent for this application will reduce the required amount of isotope by more than a factor of 3 in comparison to the current radioisotope thermoelectric generators (RTG s). Stirling is the most developed converter option of the advanced power technologies under consideration.

Thieme, Lanny G.

2000-01-01

52

An electromagnetic micro power generator for wideband environmental vibrations  

Microsoft Academic Search

This paper presents a wideband electromagnetic vibration-to-electrical micro power generator. The micro generator is capable of generating steady power over a predetermined frequency range. Power is generated by means of the relative motion between a magnet and coils fabricated over resonating cantilevers through electromagnetic induction. The reported generator covers a wide band of external vibration frequency by implementing a number

Ibrahim Sari; Tuna Balkan; Haluk Kulah

2008-01-01

53

Vibration Monitoring of Power Distribution Poles  

SciTech Connect

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.

Clark Scott; Gail Heath; John Svoboda

2006-04-01

54

DESIGN, FABRICATION AND SIMULATIONS OF MICROELECTROMAGNETIC VIBRATION-POWERED GENERATOR FOR LOW POWER MEMS  

Microsoft Academic Search

In this paper we report on the design, simulation and fabrication of a microgenerator, which converts external vibrations into electrical energy. Power is generated by means of electromagnetic transduction with static magnets positioned either side of a moving coil located on a silicon structure designed to resonate laterally in the plane of the chip. Previous millimetre scale electromagnetic generators have

S. P. Beeby; M. J. Tudor; E. Koukharenko; N. M. White; T. O'Donnell; C. Saha; S. Kulkarni

2005-01-01

55

Piezoelectric energy harvesting from hybrid vibrations  

NASA Astrophysics Data System (ADS)

The concept of harvesting energy from ambient and galloping vibrations of a bluff body with a triangular cross-section geometry is investigated. A piezoelectric transducer is attached to the transverse degree of freedom of the body in order to convert these vibrations to electrical energy. A coupled nonlinear distributed-parameter model is developed that takes into consideration the galloping force and moment nonlinearities and the base excitation effects. The aerodynamic loads are modeled using the quasi-steady approximation. Linear analysis is performed to determine the effects of the electrical load resistance and wind speed on the global damping and frequency of the harvester as well as on the onset of instability. Then, nonlinear analysis is performed to investigate the impact of the base acceleration, wind speed, and electrical load resistance on the performance of the harvester and the associated nonlinear phenomena that take place. The results show that, depending on the interaction between the base and galloping excitations, and the considered values of the wind speed, base acceleration, and electrical load resistance, different nonlinear phenomena arise while others disappear. Short- and open-circuit configurations for different wind speeds and base accelerations are assessed. The results show that the maximum levels of harvested power are accompanied by a minimum transverse displacement when varying the electrical load resistance.

Yan, Zhimiao; Abdelkefi, Abdessattar; Hajj, Muhammad R.

2014-02-01

56

Vibrationally assisted energy transfer to IF  

NASA Astrophysics Data System (ADS)

The vibrationally assisted transfer laser, a novel concept which enhances energy transfer from metastable molecules to excited electric states of species that are candidate systems for short wavelength chemical lasers, is presented. The concept uses chemically derived vibrational energy in the ground state of the acceptor series to open energy transfer pathways that would other wise be inaccessible. It is demonstrated that vibrational energy within IF(X,v) can dramatically enhance the energy transfer from NF(a) and O2(a) to IF(B), the upper level of a proven laser. It is suggested that this result may have general implications for numerous potential systems since the formation of highly nonthermal vibrational distributions within electronic ground states of diatomic molecules is a common result of exothermic reactions.

Davis, S. J.; Kessler, W. J.

1991-06-01

57

Analysis on vibration and vibration-elimination of nuclear-powered pipe  

Microsoft Academic Search

Some pipe lines of a nuclear power plant exists serious vibration that seriously affected the normal production safety. By the spectral analysis of measured time domain signal, the main vibration frequency of the pipe lines was obtained. The model analysis was processed with pipe stress analysis software CAESAR II. The natural frequency was found. According to the causes of pipe

Xiangqian Fu; Chao Wang; Si Yu; Hui Yin; Dawei Zhang; Meng Liu; Cong Chen

2011-01-01

58

Embedded fragmentation of vibrational energies  

NASA Astrophysics Data System (ADS)

Can the zero-point vibrational energies (ZPVE) of molecular clusters and crystals be evaluated as sums of ZPVE of constituent molecular fragments embedded in the cluster or crystal electrostatic environment? What is the appropriate unit of fragmentation: monomers or overlapping dimers? Can the contributions of acoustic phonons, which are fundamentally delocalized, be recuperated at satisfactory accuracy? These questions are answered by this study applying embedded monomer- and dimer-fragmentation methods to the harmonic ZPVE of hydrogen fluoride clusters, hydrogen fluoride crystal, and water clusters. Our findings are as follows: (1) ZPVE are reproduced accurately by both fragmentation schemes within a few percents of exact values or a few tenths of 1 kcal mol-1 per molecule even for crystalline hydrogen fluoride, which has acoustic phonons. (2) Both the monomer- and dimer-based fragmentation are nearly equally accurate and useful for the absolute values of ZPVE, but the latter is more reliable than the former in reproducing the relative ZPVE of cluster isomers of the same size. (3) The embedding field is essential as it renders nonzero frequencies to the translational and rotational motions of monomers and dimers, accounting for the pseudo-translational and librational motions of the entire clusters or crystals. (4) Some of these low-frequency modes of fragments are calculated to have imaginary frequencies because the fragments are not at their equilibrium geometries, causing ZPVE to be complex. The imaginary part of ZPVE, which is nonphysical and is guaranteed to vanish in the exact limit of the many-body expansion, is nonetheless a useful estimate of errors in the real part.

Sode, Olaseni; Hirata, So

2012-11-01

59

Abstract--This paper presents ambient mechanical vibrations as an alternative source for energy harvesting, especially  

E-print Network

Abstract--This paper presents ambient mechanical vibrations as an alternative source for energy harvesting, especially beneficial where alternatives such as light, wind, biomass and thermal energy are limited, e.g., powering underground sensors. Transduction of ambient kinetic energy, e.g., the vibrations

Kumar, Ratnesh

60

Vibrational energy levels of hydrogen cyanide  

Microsoft Academic Search

Sixty-nine vibrational energy levels have been calculated for HCN, using an abinitio potential energy function adjusted to the fundamentals, and also an empirical potential function by Murrell etal. The energy levels were calculated variationally, using a novel directCI procedure analogous to methods widely used in electronic structure theory. The present paper includes states with up to four quanta of excitation

Kevin M. Dunn; James E. Boggs; Peter Pulay

1986-01-01

61

Experimental Analysis of a Piezoelectric Energy Harvesting System for Harmonic, Random, and Sine on Random Vibration  

SciTech Connect

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 requirements by increasing harvested power, shifting optimal conditioning impedance, inducing significant voltage supply fluctuations and ultimately rendering idealized sinusoidal and random analyses insufficient.

Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano; Silvers, Kurt L.

2013-07-01

62

Study on Vibration Control Device Using Power Generator  

Microsoft Academic Search

In this paper, the authors developed a vibration control device (V.C.D.) using a power generator and a flywheel which is suitable for vibration suppression of a structure. The V.C.D. consists of a ball screw, a ball nut, a flywheel, a gear, and a power generator. The linear motion is converted into a rotating motion by the ball screw mechanism. The

Taichi MATSUOKA; Katsuaki SUNAKODA; Kazuhiko HIRAMOTO; Takafumi OHTAKE

63

Piezoelectric energy harvesting from traffic-induced bridge vibrations  

E-print Network

Piezoelectric energy harvesting from traffic-induced bridge vibrations Micha¨el Peigney1 harvesting of traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case-induced bridge vibrations 2 1. Introduction This paper focuses on using bridge vibrations as an energy source

Paris-Sud XI, Université de

64

Estimating Vibrational Powers Of Parts In Fluid Machinery  

NASA Technical Reports Server (NTRS)

In new method of estimating vibrational power associated with component of fluid-machinery system, physics of flow through (or in vicinity of) component regarded as governing vibrations. Devised to generate scaling estimates for design of new parts of rocket engines (e.g., pumps, combustors, nozzles) but applicable to terrestrial pumps, turbines, and other machinery in which turbulent flows and vibrations caused by such flows are significant. Validity of method depends on assumption that fluid flows quasi-steadily and that flow gives rise to uncorrelated acoustic powers in different parts of pump.

Harvey, S. A.; Kwok, L. C.

1995-01-01

65

Intramolecular Vibrational-Energy Redistribution in Fluoroform  

NASA Astrophysics Data System (ADS)

In this study, theoretical vibrational spectra and molecular dynamics of fluoroform, developed from first principles, are presented. Particular attention is given to intramolecular vibrational-energy redistribution (IVR) present in the CH overtones which exhibit multiple time scales and thus multiple mechanisms in the IVR dynamics. A 9-dimensional ab initio potential energy surface is developed to adequately account for the vibrational couplings of all modes. Furthermore, all-mode vibrational state calculations, of large primitive space dimension, are performed using a recently developed wave operator sorting algorithm (WOSA) in tandem with the recursive residue generation method (RRGM). All fundamentals, first overtones, and bimodal combination states with up to 3 quanta are presented. Also, the A_1 and E-symmetry CH polyads are characterized through the second overtone. Equilibrium geometry, rotational constants, and vibrational properties agree quantitatively with experiment in most cases. The error is systematic in origin and largely due to the error in the ab initio harmonic frequencies. New vibrational constants and resonance interactions are reported for the background modes. In contrast to the prominent CH stretch -bend Fermi resonance structure, responsible for ultrafast (t < 50 fs) energy transfer, the CH polyads also exhibit vibrational fine-structure of order 1 to 10 cm^{-1} due to background -mode coupling. This secondary coupling results in IVR on the picosecond time scale. Modifications to the WOSA are presented, based on systematic analysis of its convergence properties for the CH fundamental and first overtone, and filtered-Lanczos eigenstate analysis is performed on these states. Finally, the IVR dynamics of the CH overtones, through upsilon_{s}=4, is assessed by explicit propagation of initial zero-order overtone states. Preliminary findings are discussed.

Maynard, Andrew Thomas

66

Mechanical vibration to electrical energy converter  

DOEpatents

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.

Kellogg, Rick Allen (Tijeras, NM); Brotz, Jay Kristoffer (Albuquerque, NM)

2009-03-03

67

Effect of electrode configurations on piezoelectric vibration energy harvesting performance  

NASA Astrophysics Data System (ADS)

Piezoelectric vibration energy harvesting is an attractive technology for self-powered wireless sensor networks because of the potential to deliver power to the sensor nodes from mechanical vibration sources in the surrounding medium. Systematic device designs are required in order to increase performance along with materials development of high piezoelectric coefficients and design of circuits with high power transfer efficiency. In this work, we present refined structural and electrical modeling of interdigitated electrodes (IDEs) for piezoelectric vibration energy harvesting, followed by parametric case studies on MEMS devices. Differences in geometric parameters including the size of the electrode and the number of IDE fingers for given device dimensions lead to substantial changes in harvesting performance such as capacitance, system coupling, voltage and power. When compared with parallel plate electrodes, use of IDEs results in much higher voltage generation by a factor of ten times while similar power levels are observed for both {3-1} and {3-3} configurations at optimal electrical loading conditions.

Kim, Miso; Dugundji, John; Wardle, Brian L.

2015-04-01

68

Vibration energy harvesting by magnetostrictive material  

Microsoft Academic Search

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

Lei Wang; F. G. Yuan

2008-01-01

69

Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester  

PubMed Central

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 (?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 ?J/cycle). PMID:24366177

Kubba, Ali E.; Jiang, Kyle

2014-01-01

70

Multi-link piezoelectric structure for vibration energy harvesting  

NASA Astrophysics Data System (ADS)

Work in piezoelectric vibration energy harvesting has typically focused on single member cantilevered structures with transverse tip displacement at a known frequency, taking advantage of the optimal coupling characteristics of piezoceramics in the 3-1 bending mode. Multi-member designs could be advantageous in delivering power to a load in environments with random or wide-band vibrations. The design presented in this work consists of two hinged piezoceramic (PZT-5A) beams x-poled for series operation. Each beam measures 31.8mm x 12.7mm x 0.38mm and consists of two layers of nickel-plated piezoceramic adhered to a brass center shim. The hinge device consists of two custom-machined aluminum attachments epoxied to the end of a beam and connected using a 1.59mm diameter alloy steel dowel. A stainless steel torsion spring is placed over the pin and attached to the aluminum body to provide a restoring torque when under rotation. The design is modeled using the piezoelectric constitutive equations to solve for voltage and power for a set of electromechanical boundary conditions. Experimental measurements on the design are achieved by bolting one end of the structure to a vibration shaker and fixing the other to a rigid framework of industrial aluminum framing material. For a given frequency of vibration, power output of the structure can be obtained by measuring voltage drop across a resistive load.

Aryanpur, Rameen M.; White, Robert D.

2012-04-01

71

Resonant intermolecular transfer of vibrational energy in liquid water  

Microsoft Academic Search

Many biological, chemical and physical processes involve the transfer of energy. In the case of electronic excitations, transfer between molecules is rapid, whereas for vibrations in the condensed phase, resonant energy transfer is an unlikely process because the typical timescale of vibrational relaxation (a few picoseconds) is much shorter than that of resonant intermolecular vibrational energy transfer. For the OH-stretch

Sander Woutersen; Huib J. Bakker

1999-01-01

72

Energy harvester array using piezoelectric circular diaphragm for rail vibration  

NASA Astrophysics Data System (ADS)

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 k?, 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.

Wang, Wei; Huang, Rong-Jin; Huang, Chuan-Jun; Li, Lai-Feng

2014-12-01

73

Multistable chain for ocean wave vibration energy harvesting  

NASA Astrophysics Data System (ADS)

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.

Harne, R. L.; Schoemaker, M. E.; Wang, K. W.

2014-03-01

74

Vibration behavior of fuel-element vibration suppressors for the advanced power reactor  

NASA Technical Reports Server (NTRS)

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.

Adams, D. W.; Fiero, I. B.

1973-01-01

75

Self-powered discrete time piezoelectric vibration damper  

NASA Astrophysics Data System (ADS)

Structural vibration suppression is of great interest to the aircraft industry as it can reduce the amplitude of excessive vibration in lightly damped panels caused by conditions in their operational environment. One technique of suppressing vibration is to use passive damping techniques such as constrained layered damping incorporating viscoelastic materials. However these techniques may not be acceptable because of weight concerns or extreme temperature variations. Over the past decade much work has been done by researchers on the use of piezoelectric ceramic devices, using passive and active techniques, for structural vibration suppression. The passive piezoelectric damping devices consist of a piezoelectric element and either a resistive or resonant shunt. The resonant circuit shunt, which is analogous to a mechanical vibration absorber, gives better vibration reduction compared to the resistor shunt. This device requires a large value of inductance in order to be tuned to a particular structural vibration mode. A large value inductor can be made by a using a gyrator type circuit however the circuit needs external power. A method of vibration control using a discrete time controller and piezoelectric devices is presented. That is, this paper describes the concept of a self-powered discrete time piezoelectric vibration damper which does not need tuning to the structural resonant frequency and is powered by piezoelectric elements, i.e. does not need an external power supply. This device is referred to as a strain amplitude minimization patch (STAMP) damper. A brief description of the theory used and of the scheme is presented. Also the operation of this device is compared with other 'passive' techniques, involving piezoelectric elements, such as the resistive passive damper and the parallel resonant passive damper cases. Experimental results presented, on a cantilevered beam, demonstrate the concept and show that the device, even in its current underdeveloped form, has better damping than the simple resistor damper. Measurements taken indicate that the maximum RMS tip accelerations, at resonance, are reduced by 17.3%, 62.7% and 39.5% for the resistor, parallel resonant and STAMP damper devices, respectively, when compared to the short circuit reference condition. The performance of each device is observed when the resonant frequency of the system changes when a mass is added to the tip of the cantilever. This paper also discusses areas where improvements in the performance of the STAMP damper can be achieved.

Konak, Michael J.; Powlesland, Ian G.; van der Velden, Stephen P.; Galea, Stephen C.

1997-11-01

76

Powerful Low-Frequency Vibrators and Outlooks of their Application at Monitoring of  

E-print Network

Powerful Low-Frequency Vibrators and Outlooks of their Application at Monitoring of Engineering-chemical industrial plant of atomic energy Ministry, Russia; (5) Geophysical Survey, SB RAS, Russia Abstract of fault zone depths using changes in recorded spectra. Other applications include deep seismic profiling

Korneev, Valeri A.

77

A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources  

E-print Network

not require a very large inductor for low frequencies, and multi-modal damping is achievable without complex Accepted 18 April 2010 Available online 6 May 2010 Keywords: Piezoelectric Control Structural damping Semi-passive damping Energy harvesting a b s t r a c t In the paper, a vibration damping system powered by harvested

Paris-Sud XI, Université de

78

Compliant bistable mechanism for low frequency vibration energy harvester inspired by auditory hair bundle structures  

NASA Astrophysics Data System (ADS)

This paper presents a bio-inspired mechanism for the performance enhancement of piezoelectric power generation in vibration energy harvesting. A compliant bistable mechanism for vibration energy harvesting was explored based on the negative stiffness inspired by the auditory hair bundle structures. The proposed mechanism consists of a compliant, four-bar linkage system to mimic the hair bundle structure inside an inner ear. Our initial prototype energy harvester demonstrates that the compliant bistable mechanism featuring negative stiffness outperforms the conventional vibration energy harvester in the infra-low frequency range (1-10 Hz).

Kim, Gi-Woo; Kim, Jaehwan

2013-01-01

79

Airflow energy harvesters of metal-based PZT thin films by self-excited vibration  

NASA Astrophysics Data System (ADS)

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-?m-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 ?W at wind speeds of 12 m/s.

Suwa, E.; Tsujiura, Y.; Kurokawa, F.; Hida, H.; Kanno, I.

2014-11-01

80

Resonant vibrational energy transfer in ice Ih  

SciTech Connect

Fascinating anisotropy decay experiments have recently been performed on H{sub 2}O 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.

Shi, L.; Li, F.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

2014-06-28

81

Converged vibrational energy levels and quantum mechanical vibrational partition function of ethane  

E-print Network

Converged vibrational energy levels and quantum mechanical vibrational partition function of ethane function of ethane is calculated in the temperature range of 200­600 K using well-converged energy levels have been successfully carried out for small systems such as H2O and CH4; however, it is very difficult

Truhlar, Donald G

82

Vibration-to-electric energy conversion  

Microsoft Academic Search

Abstract: A system is proposed to convert ambient mechanicalvibration into electrical energy for use in powering autonomouslow power electronic systems. The energy is transduced throughthe use of a variable capacitor. Using microelectromechanical systems(MEMS) technology, such a device has been designed for thesystem. A low-power controller IC has been fabricated in a 0.6- mCMOS process and has been tested and measured

Scott Meninger; Jose Oscar Mur-miranda; Rajeevan Amirtharajah; Anantha P. Chandrakasan; Jeffrey H. Lang

2001-01-01

83

Powerful Low-Frequency Vibrators for Active Seismology  

SciTech Connect

In the past two decades, active seismology studies in Russia have made use of powerful (40- and 100-ton) low-frequency vibrators. These sources create a force amplitude of up to 100 tons and function in the 1.5 3, 3 6, and 5 10 Hz frequency bands. The mobile versions of the vibrator have a force amplitude of 40 tons and a 6 12 Hz frequency band. Recording distances for the 100-ton vibrator are as large as 350 km, enabling the refracted waves to penetrate down to 50 km depths. Vibrator operation sessions are highly repeatable, having distinct summer or winter spectral patterns. A long profile of seismic records allows estimation of fault zone depths using changes in recorded spectra. Other applications include deep seismic profiling, seismic hazard mapping, structural testing, stress-induced anisotropy studies, seismic station calibration, and large-structure integrity testing. The theoretical description of the low-frequency vibrator is given in the appendices, which contain numerical examples.

Alekseev, A.S.; Chichinin, I.S.; Korneev, V.A.

2003-12-01

84

Methods of performing downhole operations using orbital vibrator energy sources  

DOEpatents

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.

Cole, Jack H.; Weinberg, David M.; Wilson, Dennis R.

2004-02-17

85

Production, Delivery and Application of Vibration Energy in Healthcare  

NASA Astrophysics Data System (ADS)

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.

Abundo, Paolo; Trombetta, Chiara; Foti, Calogero; Rosato, Nicola

2011-02-01

86

New nonlinear vibration energy harvesters based on PVDF hybrid fluid diaphragm  

NASA Astrophysics Data System (ADS)

A low resonance frequency piezoelectric energy harvesting using a hybrid fluid diaphragm (HFD) is presented. This paper describes the design, fabrication and measurement of such device for harvesting energy from environmental vibrations. The HFD consists in an incompressible fluid confined between two thin piezoelectric membranes. The output voltage and power of the PVDF HFD are studied based on experimental and simulation results. Compared with conventional vibration harvester, this proposed solution is very simple and suitable for miniaturization and integration.

Huet, F.; Formosa, F.; Badel, A.

2014-11-01

87

Power extraction using flow-induced vibration of a circular cylinder placed near another fixed cylinder  

NASA Astrophysics Data System (ADS)

We conducted an experiment in a towing tank to investigate the performance of an energy extraction system using the flow-induced vibration of a circular cylinder. This experiment tested three different cases involving the following arrangements of cylinder(s) of identical diameter: the upstream fixed-downstream movable arrangement (case F); the upstream movable-downstream fixed arrangement (case R); and a movable isolated cylinder (case I). In cases F and R, the separation distance (ratio of the distance between the centers of the two cylinders to their diameters) is fixed at 1.30. Measurement results show that while cases F and I generate vortex-induced vibration (VIV) resonance responses, case R yields wake-induced vibration (WIV) at reduced velocity over 9.0, which is significantly larger than that of the VIV response, leading to the induction of higher electronic power in a generator. Accordingly, primary energy conversion efficiency is higher in the case involving WIV.

Nishi, Yoshiki; Ueno, Yuta; Nishio, Masachika; Quadrante, Luis Antonio Rodrigues; Kokubun, Kentaroh

2014-05-01

88

Experimental study of a self-powered and sensing MR-damper-based vibration control system  

NASA Astrophysics Data System (ADS)

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.

Sapi?ski, Bogdan

2011-10-01

89

Vibrational energy transfer in ultracold molecule - molecule collisions  

E-print Network

We present a rigorous study of vibrational relaxation in p-H2 + p-H2 collisions at cold and ultracold temperatures and identify an efficient mechanism of ro-vibrational energy transfer. If the colliding molecules are in different rotational and vibrational levels, the internal energy may be transferred between the molecules through an extremely state-selective process involving simultaneous conservation of internal energy and total rotational angular momentum. The same transition in collisions of distinguishable molecules corresponds to the rotational energy transfer from one vibrational state of the colliding molecules to another.

Goulven Quéméner; Naduvalath Balakrishnan; Roman V. Krems

2008-01-15

90

Membrane-type vibrational energy harvester based on a multi-layered piezoelectric membrane  

NASA Astrophysics Data System (ADS)

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.

Yoo, Seunghwan; Kim, Jonghun; Park, Suk-in; Jang, Cheol-Yong; Jeong, Hakgeun

2014-03-01

91

Vibration-based energy harvesting with stacked piezoelectrets  

SciTech Connect

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.

Pondrom, P., E-mail: ppondrom@nt.tu-darmstadt.de [Institute for Telecommunications Technology, Technische Universität Darmstadt, Merckstr. 25, 64283 Darmstadt (Germany); System Reliability and Machine Acoustics SzM, Technische Universität Darmstadt, Magdalenenstr. 4, 64289 Darmstadt (Germany); Hillenbrand, J.; Sessler, G. M. [Institute for Telecommunications Technology, Technische Universität Darmstadt, Merckstr. 25, 64283 Darmstadt (Germany); Bös, J.; Melz, T. [System Reliability and Machine Acoustics SzM, Technische Universität Darmstadt, Magdalenenstr. 4, 64289 Darmstadt (Germany)

2014-04-28

92

Synchronized Multiple-Array Vibrational Device for Microelectromechanical System Electrostatic Energy Harvester  

NASA Astrophysics Data System (ADS)

In this paper, we describe a novel structure of a vibrational micro-electro-mechanical system (MEMS) device for power generation enhancement. A synchronized multiple-array vibrational device, in which movable plates are connected by rods, increases the area of the movable plate in the energy conversion region and couples the phase of movement. The fabricated device resonates at approximately 1430 Hz with an acceleration amplitude of 6 m/s2 and nanoampere-order AC current is generated. These results confirm that this MEMS vibrational device will contribute to the progress in energy harvesting.

Ono, Kazuyoshi; Sato, Norio; Shimamura, Toshishige; Ugajin, Mamoru; Sakata, Tomomi; Mutoh, Shin'ichiro; Kodate, Junichi; Jin, Yoshito; Sato, Yasuhiro

2012-05-01

93

Resonance tracking and vibration stablilization for high power ultrasonic transducers.  

PubMed

Resonant frequency shift and electrical impedance variation are common phenomena in the application of high power ultrasonic transducers, e.g. in focused ultrasound surgery and in cutting. They result in low power efficiency and unstable vibration amplitude. To solve this problem, a driving and measurement system has been developed to track the resonance of high power transducers and to stabilise their vibration velocity. This has the ability to monitor the operating and performance parameters of the ultrasonic transducers in real time. The configuration of the system, with its control algorithm implemented in LabVIEW (National Instruments, Newbury, UK), ensures flexibility to suit different transducers and load conditions. In addition, with different programs, it can be utilised as a high power impedance analyser or an instantaneous electrical power measurement system for frequencies in the MHz range. The effectiveness of this system has been demonstrated in detailed studies. With it, high transducer performance at high power can be achieved and monitored in real time. PMID:23928264

Kuang, Y; Jin, Y; Cochran, S; Huang, Z

2014-01-01

94

Vibrational energy levels of CH5(+).  

PubMed

We present a parallelized contracted basis-iterative method for calculating numerically exact vibrational energy levels of CH(5)(+) (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 200x10(6) 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. PMID:19102521

Wang, Xiao-Gang; Carrington, Tucker

2008-12-21

95

A Hybrid Indoor Ambient Light and Vibration Energy Harvester for Wireless Sensor Nodes  

PubMed Central

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

Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei

2014-01-01

96

A hybrid indoor ambient light and vibration energy harvester for wireless sensor nodes.  

PubMed

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

Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei

2014-01-01

97

Vibration-assisted resonance in photosynthetic excitation-energy transfer  

NASA Astrophysics Data System (ADS)

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.

Irish, E. K.; Gómez-Bombarelli, R.; Lovett, B. W.

2014-07-01

98

Extension of vibrational power flow techniques to two-dimensional structures  

NASA Technical Reports Server (NTRS)

In the analysis of the vibration response and structure-borne vibration transmission between elements of a complex structure, statistical energy analysis (SEA) or Finite Element Analysis (FEA) are generally used. However, an alternative method is using vibrational power flow techniques which can be especially useful in the mid- frequencies between the optimum frequency regimes for FEA and SEA. Power flow analysis has in general been used on one-dimensional beam-like structures or between structures with point joints. In this paper, the power flow technique is extended to two-dimensional plate like structures joined along a common edge without frequency or spatial averaging the results, such that the resonant response of the structure is determined. The power flow results are compared to results obtained using FEA at low frequencies and SEA at high frequencies. The agreement with FEA results is good but the power flow technique has an improved computational efficiency. Compared to the SEA results the power flow results show a closer representation of the actual response of the structure.

Cuschieri, J. M.

1987-01-01

99

Enhancing light-harvesting power with coherent vibrational interactions: a quantum heat engine picture  

E-print Network

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 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 quantify its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's applicability for realistic biological structures.

Nathan Killoran; Susana F. Huelga; Martin B. Plenio

2014-12-12

100

Micromachined silicon Generator for Harvesting Power from Vibrations  

Microsoft Academic Search

This paper describes the design, simulation and fabrication of an electromagnetic device for generating electrical energy from vibrations. A range of dimensions has been simulated using ANSYS in order to determine natural frequencies and material stresses. A 300µm wide paddle beam gives a natural frequency of 6.4 kHz for the mode of operation and induced stresses at maximum amplitudes are

S. P. Beeby; M. J. Tudor; E. Koukharenko; N. M. White; T. O'Donnell; C. Saha; S. Kulkarni; S. Roy

101

[The influence of posture on transmission and absorption of vibration energy in whole body vibration exercise].  

PubMed

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. PMID:20229446

Berschin, G; Sommer, H-M

2010-03-01

102

A chaotic vibration energy harvester using magnetic material  

NASA Astrophysics Data System (ADS)

This paper presents a new wideband electromagnetic vibration energy harvester (VEH) composed of a magnetic core embedded into the coil axis. The magnetic core generates a nonlinear magnetic force, which gives rise to the nonlinearity in the behavior of the VEH. Moreover, the magnetic core increases the flux linkage with the coil. These features improve the operational bandwidth and output power of the VEH. Numerical analysis and experimental measurements reveal that the operational bandwidth of the proposed VEH is over 30 Hz in which the output power is kept about 0.1 mW. Moreover, the proposed VEH operates by complicated oscillation due to nonlinear forces acting on the oscillator. Evaluation of the Lyapunov exponent for the measured oscillation suggests that the proposed VEH produces chaotic oscillation.

Sato, Takahiro; Igarashi, Hajime

2015-02-01

103

Simple method for measuring vibration amplitude of high power airborne ultrasonic transducer: using thermo-couple.  

PubMed

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. PMID:24246149

Saffar, Saber; Abdullah, Amir

2014-03-01

104

Nonlinear vibration control and energy harvesting of a beam using a nonlinear energy sink and a piezoelectric device  

NASA Astrophysics Data System (ADS)

This paper presents an optimal design for a system comprising a nonlinear energy sink (NES) and a piezoelectric-based vibration energy harvester attached to a free-free beam under shock excitation. The energy harvester is used for scavenging vibration energy dissipated by the NES. Grounded and ungrounded configurations are examined and the systems parameters are optimized globally to both maximize the dissipated energy by the NES and increase the harvested energy by piezoelectric element. A satisfactory amount of energy has been harvested as electric power in both configurations. The realization of nonlinear vibration control through one-way irreversible nonlinear energy pumping and optimizing the system parameters result in acquiring up to 78 percent dissipation of the grounded system energy.

Nili Ahmadabadi, Z.; Khadem, S. E.

2014-09-01

105

Energy harvesting of random wide-band vibrations with applications to an electro-magnetic rotational energy harvester  

E-print Network

In general, vibration energy harvesting is the scavenging of ambient vibration by transduction of mechanical kinetic energy into electrical energy. Many mechanical or electro-mechanical systems produce mechanical vibrations. ...

Trimble, A. Zachary

2011-01-01

106

Optimization design of high power ultrasonic circular ring radiator in coupled vibration  

Microsoft Academic Search

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

Long Xu; Shuyu Lin; Wenxu Hu

2011-01-01

107

Stresa, Italy, 26-28 April 2006 SCALING EFFECTS FOR ELECTROMAGNETIC VIBRATIONAL POWER  

E-print Network

Stresa, Italy, 26-28 April 2006 SCALING EFFECTS FOR ELECTROMAGNETIC VIBRATIONAL POWER GENERATORS This paper investigates how the power generated by electromagnetic based vibrational power generators scales with the dimension of the generator. The effects of scaling on the magnetic fields, the coil parameters

Boyer, Edmond

108

Piezoelectric Power Scavenging of Mechanical Vibration and R H Middleton  

E-print Network

vibrations present in the nozzle in water jet assisted drilling. Generating electricity locally at the nozzle stress. Vibration source Water jet assisted drilling gives rise to large mechanical vibrations because piezoelectric material. In some mining applications, eg water jet drilling; large high frequency vibrations may

Duffy, Ken

109

Micro-scale piezoelectric vibration energy harvesting: From fixed-frequency to adaptable-frequency devices  

NASA Astrophysics Data System (ADS)

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 hundred milliwatts and are falling steadily as improvements are made, it is feasible to use energy harvesting to power WSNs. This research begins by presenting the results of a thorough survey of ambient vibrations in the machine room of a large campus building, which found that ambient vibrations are low frequency, low amplitude, time varying, and multi-frequency. The modeling and design of fixed-frequency micro scale energy harvesters are then presented. The model is able to take into account rotational inertia of the harvester's proof mass and it accepts arbitrary measured acceleration input, calculating the energy harvester's voltage as an output. The fabrication of the micro electromechanical system (MEMS) energy harvesters is discussed and results of the devices harvesting energy from ambient vibrations are presented. The harvesters had resonance frequencies ranging from 31 - 232 Hz, which was the lowest reported in literature for a MEMS device, and produced 24 pW/g2 - 10 nW/g2 of harvested power from ambient vibrations. A novel method for frequency modification of the released harvester devices using a dispenser printed mass is then presented, demonstrating a frequency shift of 20 Hz. Optimization of the MEMS energy harvester connected to a resistive load is then presented, finding that the harvested power output can be increased to several microwatts with the optimized design as long as the driving frequency matches the harvester's resonance frequency. A framework is then presented to allow a similar optimization to be conducted with the harvester connected to a synchronously switched pre-bias circuit. With the realization that the optimized energy harvester only produces usable amounts of power if the resonance frequency and driving frequency match, which is an unrealistic situation in the case of ambient vibrations which change over time and are not always known a priori, an adaptable-frequency energy harvester was designed. The adaptable-frequency harvester works by taking advantage of the coupling between

Miller, Lindsay Margaret

110

A wideband vibration energy harvester based on a folded asymmetric gapped cantilever  

NASA Astrophysics Data System (ADS)

This paper reports a wideband multi-mass multi-spring piezoelectric vibration energy harvester (VEH) based on a folded asymmetric gapped cantilever, which enables multiple resonant modes formed by pure bending of every stage. Moreover, the heaviest proof mass is placed at the last stage of the cantilever to increase the harvested power. The VEH's energy conversion efficiency is further increased using the asymmetric gapped structure. A prototype has been developed and characterized. The experimental results match with finite element simulation well. The prototype was tested on an air conditioning unit to demonstrate its energy harvesting capability with a realistic broadband vibration source.

Hu, Yating; Xu, Yong

2014-02-01

111

Magnetic induction systems to harvest energy from mechanical vibrations  

E-print Network

This thesis documents the design process for magnetic induction systems to harvest energy from mechanical vibrations. Two styles of magnetic induction systems - magnet-through-coil and magnet-across-coils - were analyzed. ...

Jonnalagadda, Aparna S

2007-01-01

112

Ultrafast vibrational energy relaxation of the water bridge.  

PubMed

We report the energy relaxation of the OH stretch vibration of HDO molecules contained in an HDO:D(2)O water bridge using femtosecond mid-infrared pump-probe spectroscopy. We found that the vibrational lifetime is shorter (~630 ± 50 fs) than for HDO molecules in bulk HDO:D(2)O (~740 ± 40 fs). In contrast, the thermalization dynamics following the vibrational relaxation are much slower (~1.5 ± 0.4 ps) than in bulk HDO:D(2)O (~250 ± 90 fs). These differences in energy relaxation dynamics strongly indicate that the water bridge and bulk water differ on a molecular scale. PMID:21997703

Piatkowski, Lukasz; Wexler, Adam D; Fuchs, Elmar C; Schoenmaker, Hinco; Bakker, Huib J

2012-05-14

113

Enhanced vibration based energy harvesting using embedded acoustic black holes  

NASA Astrophysics Data System (ADS)

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.

Zhao, L.; Semperlotti, F.; Conlon, S. C.

2014-03-01

114

Extracting energy from Vortex-Induced Vibrations: A parametric study  

Microsoft Academic Search

Here, Vortex-Induced Vibrations (VIVs) of a circular cylinder are analyzed as a potential source for energy harvesting. To this end, VIV is described by a one-degree-of-freedom model where fluid forces are introduced from experimental data from forced vibration tests. The influence of some influencing parameters, like the mass ratio m? or the mechanical damping ? in the energy conversion factor

Antonio Barrero-Gil; Santiago Pindado; Sergio Avila

115

Development and experiments of a micro piezoelectric vibration energy storage device  

NASA Astrophysics Data System (ADS)

According to the difficult replacement and poor endurance of the battery for wireless sensor network nodes, a micro piezoelectric vibration energy storage device was developed in this paper. The electric generating performance of the device was then tested on a self-made experimental system. It is shown that the developed energy storage device can collect effectively surrounding vibrations. What is more, the inherent frequency of the device can be expanded by adjusting the span between its two piezoelectric vibrators. It is also found that the output of the device depends badly on the external load resistance. With the increasing of load resistance, the output voltage increases while the output power increases first then decreases. The output power has an optimal associated load resistance. The output power achieves a maximum value 115.2 ?W when the load resistance is 200 k?. With the energy storing circuit, the output electric energy of the device can effectively act as a power source for any low power micro electron devices such as wireless sensor network nodes. It is believed that this work may be practical for energy supplying of the low power micro electron devices.

Chen, Guangzhu; Meng, Qingchun; Fu, Hailing; Bao, Jiusheng

2013-10-01

116

Electromagnetic energy harvester with repulsively stacked multilayer magnets for low frequency vibrations  

E-print Network

traffic induced bridge vibrations. First, the governing equation for electromechanical coupling from the ambient vibration of the bridge. Keywords: energy harvesting, electromagnetic harvester, bridge vibration, linear generator, multilayer magnets. #12;1 1. Introduction Wireless sensors are now

Stanford University

117

Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber  

NASA Astrophysics Data System (ADS)

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.

Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

2014-04-01

118

Design and simulation of a capacitive vibration energy generator based on radioisotope 63Ni  

Microsoft Academic Search

This paper presents the design and simulation of energy harvesting system based on radioisotope. This energy generator is a typical spring-mass-damping system that converts nuclear energy into mechanical vibration energy. The vibration energy is converted into extricable electrical energy by a capacitive energy converter which consists of a top Pt electrode and a bottom Al electrode deposited on vibration mass.

Yanfei Li; Zaijun Cheng; Haisheng San; Yingxian Duo; Xuyuan Chen

2010-01-01

119

Spectroscopic probes of vibrationally excited molecules at chemically significant energies  

SciTech Connect

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.

Rizzo, T.R. [Univ. of Rochester, NY (United States)

1993-12-01

120

Low Frequency Vibration Energy Harvester Using Spherical Permanent Magnet with Non-uniform Mass Distribution  

NASA Astrophysics Data System (ADS)

We present a non-resonant vibration energy harvesting device using springless spherical permanent magnet with non-uniform mass distribution as a proof mass. The magnet has its center-of-mass below the geometrical center, which generates a roly-poly-like motion in response to external vibrations. Two different types of magnet assemblies with different center-of-mass position have been fabricated and tested. Using the roly-poly-like magnets, proof-of-concept electromagnetic energy harvesters have been fabricated and tested. Moreover, effect of ferrofluid as a lubricant has been tested with the fabricated energy harvester. Maximum open-circuit voltage of 154.4mV and output power of 4.53?W have been obtained at 3g vibration at 12Hz with the fabricated device.

Choi, Y.; Ju, S.; Chae, S. H.; Jun, S.; Park, S. M.; Lee, S.; Lee, H. W.; Ji, C.-H.

2013-12-01

121

Vibration-translation energy transfer in vibrationally excited diatomic molecules. Ph.D. Thesis - York Univ., Toronto  

NASA Technical Reports Server (NTRS)

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.

Mckenzie, R. L.

1976-01-01

122

Optimization design of high power ultrasonic circular ring radiator in coupled vibration.  

PubMed

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. PMID:21529873

Xu, Long; Lin, Shuyu; Hu, Wenxu

2011-10-01

123

IEEE Power and Energy  

NSDL National Science Digital Library

IIEEE presents Power and Energy magazine online. The latest issue as well as several previous issues are available online for free use. Columns of Power and Energy highlight history, industry news, standards, and opinion articles. The archives currently go back to 2009.

2003-01-01

124

Coupled analysis of multi-impact energy harvesting from low-frequency wind induced vibrations  

NASA Astrophysics Data System (ADS)

Energy need from off-grid locations has been critical for effective real-time monitoring and control to ensure structural safety and reliability. To harvest energy from ambient environments, the piezoelectric-based energy-harvesting system has been proven very efficient to convert high frequency vibrations into usable electrical energy. However, due to the low frequency nature of the vibrations of civil infrastructures, such as those induced from vehicle impacts, wind, and waves, the application of a traditional piezoelectric-based energy-harvesting system is greatly restrained since the output power drops dramatically with the reduction of vibration frequencies. This paper focuses on the coupled analysis of a proposed piezoelectric multi-impact wind-energy-harvesting device that can effectively up-convert low frequency wind-induced vibrations into high frequency ones. The device consists of an H-shape beam and four bimorph piezoelectric cantilever beams. The H-shape beam, which can be easily triggered to vibrate at a low wind speed, is originated from the first Tacoma Narrows Bridge, which failed at wind speeds of 18.8 m s?1 in 1940. The multi-impact mechanism between the H-shape beam and the bimorph piezoelectric cantilever beams is incorporated to improve the harvesting performance at lower frequencies. During the multi-impact process, a series of sequential impacts between the H-shape beam and the cantilever beams can trigger high frequency vibrations of the cantilever beams and result in high output power with a considerably high efficiency. In the coupled analysis, the coupled structural, aerodynamic, and electrical equations are solved to obtain the dynamic response and the power output of the proposed harvesting device. A parametric study for several parameters in the coupled analysis framework is carried out including the external resistance, wind speed, and the configuration of the H-shape beam. The average harvested power for the piezoelectric cantilever beam reaches 11.77 mW with a power density of 6.11 mW cm?3 under the wind speed of 10 m s?1, which is sufficient to power small sensors. The average harvested power can further reach up to 45 mW under the wind speed of 14 m s?1.

Zhu, Jin; Zhang, Wei

2015-04-01

125

Vibrational and collision energy effects on the reaction with methanol  

E-print Network

Vibrational and collision energy effects on the reaction of CH3CHO¿ with methanol Ho-Tae Kim, Jianbo Liu, and Scott L. Anderson Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 measured for reaction of acetaldehyde cation with methanol over a center-of-mass collision energy range

Anderson, Scott L.

126

Low Head, Vortex Induced Vibrations River Energy Converter  

SciTech Connect

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.

Bernitsas, Michael B.; Dritz, Tad

2006-06-30

127

Characterization of a water pump for drum-type washing machine by vibration power approach  

NASA Astrophysics Data System (ADS)

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.

Heo, YongHwa; Kim, Kwang-joon

2015-03-01

128

A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot  

Microsoft Academic Search

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

Yingxiang Liu; Weishan Chen; Junkao Liu; Shengjun Shi

2010-01-01

129

A two-dimensional broadband vibration energy harvester using magnetoelectric transducer  

SciTech Connect

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})

Yang, Jin, E-mail: yangjin@cqu.edu.cn; Wen, Yumei; Li, Ping; Yue, Xihai; Yu, Qiangmo; Bai, Xiaoling [Department of Optoelectronic Engineering, Research Center of Sensors and Instruments, Chongqing University, Chongqing 400044 (China)] [Department of Optoelectronic Engineering, Research Center of Sensors and Instruments, Chongqing University, Chongqing 400044 (China)

2013-12-09

130

Vibration characterisation of cymbal transducers for power ultrasonic applications  

NASA Astrophysics Data System (ADS)

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 results also show that the device can be accurately tuned using finite element modelling and that the cymbal exhibits a modal response as predicted by the finite element models.

Bejarano, F.; Feeney, A.; Lucas, M.

2012-08-01

131

Modeling and analysis of a micromachined piezoelectric energy harvester stimulated by ambient random vibrations  

NASA Astrophysics Data System (ADS)

Piezoelectric energy microgenerators are devices that continuously generate electricity when they are subjected to varying mechanical strain due to vibrations. They can generate electrical power up to 100 ?W which can be used to drive various sensing and actuating MEMS devices. Today, piezoelectric energy harvesters are considered autonomous and reliable energy sources to actuate low power microdevices such as wireless sensor networks, indoor-outdoor monitoring, facility management and biomedical applications. The advantages of piezoelectric energy harvesters including high power density, moderate output power and CMOS compatible fabrication in particular with aluminum nitride (AlN) have fuelled and motivated researchers to develop MEMS based energy harvesters. Recently, the use of AlN as a piezoelectric material has increased fabrication compatibility, enabling the realization of smart integrated systems on chip which include sensors, actuators and energy storage. Piezoelectric MEMS energy microgenerator is used to capture and transform the available ambient mechanical vibrations into usable electric energy via resonant coupling in the thin film piezoelectric material. Analysis and modeling of piezoelectric energy generators are very important aspects for improved performance. Aluminum nitride as the piezoelectric material is sandwiched between two electrodes. The device design includes a silicon cantilever on which the AlN film is deposited and which features a seismic mass at the end of the cantilever. Beam theory and lumped modeling with circuit elements are applied for modeling and analysis of the device operation at various acceleration values. The model shows good agreement with the experimental findings, thus giving confidence in the model.

Alamin Dow, Ali B.; Al-Rubaye, Hasan A.; Koo, David; Schneider, Michael; Bittner, Achim; Schmid, Ulrich; Kherani, Nazir P.

2011-06-01

132

Electromagnetic Vibration Energy Harvester Using Springless Proof Mass and Ferrofluid as a Lubricant  

NASA Astrophysics Data System (ADS)

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 71.26?W has been obtained at 40.8? with the device with ferrofluid lubrication.

Chae, S. H.; Ju, S.; Choi, Y.; Jun, S.; Park, S. M.; Lee, S.; Lee, H. W.; Ji, C.-H.

2013-12-01

133

THE INTRAMOLECULAR VIBRATIONAL ENERGY DISTRIBUTION OF INFRARED MULTIPHOTON EXCITED MOLECULES  

E-print Network

the intramolecular dynamics of infrared multiphoton excited molecules. Time-resolved spontaneous and coherent anti-Stokes Raman spectroscopy was employed to measure the energy distribution among vibrational modes immediately with English, I was depressed and lacked confidence. He encouraged me at that time, and has continued to give

Mazur, Eric

134

DEAP-based energy harvesting using vortex-induced vibrations  

NASA Astrophysics Data System (ADS)

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.

Hoffstadt, Thorben; Heinze, Robert; Wahl, Tim; Kameier, Frank; Maas, Jürgen

2014-03-01

135

Harvesting vibration energy by a triple-cantilever based triboelectric nanogenerator  

E-print Network

device has been designed for harvesting vibration energy, especially at low frequencies, opening its application as a new energy technology. 1 Introduction There are tremendous amounts of ambient vibration

Wang, Zhong L.

136

Tunable Vibration Energy Harvester for Condition Monitoring of Maritime Gearboxes  

NASA Astrophysics Data System (ADS)

This paper reports on a new tuning concept, which enables the operation of a vibration generator for energy autonomous condition monitoring of maritime gearboxes. The tuning concept incorporates a circular tuning magnet, which interacts with a coupling magnet attached to the active transducer element. The tuning range can be tailored to the application by careful design of the gap between tuning magnet and coupling magnet. A total rotation angle of only 180° is required for the tuning magnet in order to obtain the full frequency bandwidth. The tuning concept is successfully demonstrated by charging a 0.6 F capacitor on the basis of physical vibration profiles taken from a gearbox.

Hoffmann, D.; Willmann, A.; Folkmer, B.; Manoli, Y.

2014-11-01

137

Improved mechanical reliability of MEMS electret based vibration energy harvesters for automotive applications  

NASA Astrophysics Data System (ADS)

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.

Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.

2014-11-01

138

Ride Vibrations on a 7·5 kW Rotary Power Tiller  

Microsoft Academic Search

The power tiller has become a versatile power source for small and medium size farms in India owing to development of a variety of matching equipment. In order to overcome the problem of drudgery involved in its operation, an operator’s seat has been designed and developed. Power tiller ride vibration levels have been measured at man-seat interface along three mutually

C. R. Mehta; P. S. Tiwari; A. C. Varshney

1997-01-01

139

High power low frequency ultrasonic transducer: vibration amplitude measurements by an optical interferometric method  

Microsoft Academic Search

High power low frequency ultrasonic systems used in sonochemistry, for cell disruption or sonophoresis are usually calibrated and controlled with procedures (electrical power measurement, calorimetry, chemical dosimetry) that just give an indication about performance. The surface vibration amplitude, both in air and in water of a high power low frequency ultrasonic system, is determined by laser interferometry combined to calculation.

Alain Boucaud; Nicolas Felix; Luis Pizarro; Frederic Patat

1999-01-01

140

Vibration control based on dynamic compensation in an electric power steering system  

Microsoft Academic Search

The market for power assist steering in small cars is expanding. Most common among the products rapidly coming to the market are electrically powered hydraulic units and electrically powered systems that act directly on the steering column or on the steering gear. Control system stability and system vibrations are always a concern. While the system synthesized in this paper is

A. T. Zaremba; M. K. Liubakka; R. M. Stuntz

1997-01-01

141

Ultrafast vibrational dynamics and energy transfer in imidazolium ionic liquids.  

PubMed

Femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) is used as a probe for monitoring the vibrational dynamics of room temperature ionic liquids (ILs). The experiments are performed on a series of 1,3-dialkylimidazolium ILs containing the bis(trifluoromethylsulfonyl)imide [NTf2] anion. The effect of methylation of the cationic C2 position on the dephasing time is studied analyzing [NTf2]-ILs of 1-ethyl-3-methylimidazolium [EMIM], 1-ethyl-2,3-dimethylimidazolium [EMMIM], 1-butyl-3-methylimidazolium [BMIM], and 1-butyl-2,3-dimethylimidazolium [BMMIM]. Raman coherences are excited around ?1400 cm(-1), and the vibrational dephasing of the modes in the fingerprint region is monitored as a function of time. The results indicate that vibrational energy transfer occurs governed by the interionic interactions. This is suggested by mode beating involving vibrations beyond the excitation spectrum as well as systematic differences in the temporal dephasing behavior. In contrast, the length of the cationic alkyl side chain has a negligible impact on the vibrational dynamics. PMID:24697246

Namboodiri, Mahesh; Kazemi, Mehdi Mohammad; Zeb Khan, Tahir; Materny, Arnulf; Kiefer, Johannes

2014-04-23

142

Automatic generation of force fields and property surfaces for use in variational vibrational calculations of anharmonic vibrational energies and zero-point vibrational averaged properties.  

PubMed

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. PMID:17014167

Kongsted, Jacob; Christiansen, Ove

2006-09-28

143

Automatic generation of force fields and property surfaces for use in variational vibrational calculations of anharmonic vibrational energies and zero-point vibrational averaged properties  

NASA Astrophysics Data System (ADS)

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 Møller-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.

Kongsted, Jacob; Christiansen, Ove

2006-09-01

144

Rotational and Vibrational Energy Transfer from the First Overtone Strech of Acetylene  

NASA Astrophysics Data System (ADS)

Gas lasers that are optically pumped by solid state devices are currently being considered for applications that require high powers and high beam quality. Optical pumping in the 1-2 ?m region is of interest as there are efficient diode laser sources that operate in this spectral range. An optically pumped C_2H_2 laser was recently demonstrated by Wolfgang et al. at the University of New Mexico. Excitation of the CH overtone transition (v_C_H=2) at 1.52 ?m yielded lasing on an asymmetric stretch combination band centered at 3.1 ?m. Collisional energy transfer data for the v_C_H=2 level is needed for analysis and modeling of the laser performance. Although there have been numerous studies of energy transfer for vibrationally excited acetylene, the v_C_H=2 level has received very little attention. We are currently examining state-to-state ro-vibrational energy transfer processes for v_C_H=2 in self-collisions using a pulsed IR pump- UV probe technique. Pure rotational transfer has been characterized and rapid vibrational transfer has also been observed. Identification of the collisionally populated vibrational levels and measurements of the transfer rate constants are in progress.

Heaven, M. C.; Han, Jiande; Freel, Keith

2010-06-01

145

A Branched Beam-Based Vibration Energy Harvester  

NASA Astrophysics Data System (ADS)

In this paper, a strategy to utilize a branched beam system to improve the frequency response characteristic of vibration energy harvesting is demonstrated. A basic unit of the device consists of several branch beams with proof mass at their ends and one main cantilever beam with a piezoelectric component at its root and proof mass at its end. The device can utilize the resonance of the branch beams and main beam to generate multiple output voltage peaks, providing a better frequency response characteristic than that of the conventional piezoelectric vibration energy harvester. Multiple branch structure and multiple basic units with similar structures can be connected to generate more output voltage peaks in the frequency response characteristic. Only one piezoelectric component is needed in the device, which makes it competitive in the management of harvested electric energy.

Zhang, Guangcheng; Hu, Junhui

2014-09-01

146

Investigation of Vibrational Energy Transfer in Connected Structures  

NASA Technical Reports Server (NTRS)

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.

Hwang, C.; Pi, W. S.

1973-01-01

147

Investigation of folded spring structures for vibration-based piezoelectric energy harvesting  

NASA Astrophysics Data System (ADS)

This paper presents a fixed-fixed folded spring as an alternative elastic element for beam-based piezoelectric energy harvesting. In order to harvest energy from low frequency vibration in an optimal manner, the natural/operational frequencies of harvesters must be reduced to match low frequency input vibrations. Therefore, natural frequency reduction of vibration-based energy harvesters is critical to maximize output power at low operational frequency. The mechanical optimization of cantilever-based piezoelectric energy harvesters is limited by residual stress-based beam curling that produced through microfabrication adding additional mechanical stiffness to the system. The fixed-fixed folded spring structure presented in this paper allows for increased effective beam length and residual stress relaxation, without out of plane beam curling to further reducing the natural frequency. Multiple designs of folded spring energy harvesters are presented to demonstrate the effect of important design parameters. It is shown that the folded spring harvesters were capable of harvesting electricity at low natural frequencies, ranging from 45?Hz to 3667?Hz. Additionally, the harvesters were shown to be insensitive to microfabrication-based residual stress beam curling. The maximum power output achieved by the folded spring harvesters was 690.5?nW at 226.3?Hz for a single harvesting element of an array, with a PZT layer thickness of 0.24??m. The work presented in this paper demonstrates that the fixed-fixed folded spring can be used as a viable structural element for low frequency piezoelectric energy harvesting to take advantage of ambient vibrations found in low frequency applications.

Lueke, J.; Rezaei, M.; Moussa, W. A.

2014-12-01

148

A POWER FLOW METHOD FOR EVALUATING VIBRATION FROM UNDERGROUND RAILWAYS  

E-print Network

of an underground-tunnel showing the different structural components (in this figure the floating slab is mounted into nearby buildings. Many methods are used to decrease vibration levels in nearby structures. One is the use of floating-slab track as Slab bearings Floating Slab Soil Tunnel Rail Rail pads Figure 1: Layout

Talbot, James P.

149

White Noise Responsiveness of an AlN Piezoelectric MEMS Cantilever Vibration Energy Harvester  

NASA Astrophysics Data System (ADS)

This paper reports the design, analysis and experimental characterisation of a piezoelectric MEMS cantilever vibration energy harvester, the enhancement of its power output by adding various values of end mass, as well as assessing the responsiveness towards white noise. Devices are fabricated using a 0.5 ?m AlN on 10 ?m doped Si process. Cantilevers with 5 mm length and 2 mm width were tested at either unloaded condition (MC0: fn 577 Hz) or subjected to estimated end masses of 2 mg (MC2: fn 129 Hz) and 5 mg (MC5: fn 80 Hz). While MC0 was able to tolerate a higher drive acceleration prior to saturation (7 g with 0.7 ?W), MC5 exhibited higher peak power attainable at a lower input vibration (2.56 ?W at 3 ms?2). MC5 was also subjected to band-limited (10 Hz to 2 kHz) white noise vibration, where the power response was only a fraction of its resonant counterpart for the same input: peak instantaneous power >1 ?W was only attainable beyond 2 g of white noise, whereas single frequency resonant response only required 2.5 ms?2. Both the first resonant response and the band-limited white noise response were also compared to a numerical model, showing close agreements.

Jia, Y.; Seshia, A. A.

2014-11-01

150

Energy Harvesting from Ambient Vibrations with Arbitrary In-Plane Motion Directions Using a Magnetostrictive/Piezoelectric Laminate Composite Transducer  

NASA Astrophysics Data System (ADS)

A magnetoelectric (ME) vibration energy harvester has been designed to scavenge sufficient energy from ambient vibration with arbitrary motion directions in a plane and over a range of frequencies. In the harvester, a circular-cross-section cantilever rod is adopted to extract the vibration energy due to its ability to host accelerations in arbitrary in-plane motion directions. The magnetic coupling between the magnet and the ME transducer results in nonlinear oscillation of the cantilever rod with increased frequency bandwidth. To achieve optimal vibration energy harvesting performance, the effects of the nonlinear vibration and the harvester parameters including the magnetic circuit and the separation distance on the electrical output and the?working bandwidth are analyzed. The experimental results show that the harvester can scavenge vibration energy in arbitrary in-plane directions, exhibiting a bandwidth of 4.0 Hz and maximum power of 0.22 mW at acceleration of 0.6 g (with g = 9.8 m s-2).

Yang, Jin; Wen, Yumei; Li, Ping; Yue, Xihai; Yu, Qiangmo

2014-07-01

151

A review of vibration problems in power station boiler feed pumps  

NASA Technical Reports Server (NTRS)

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.

France, David

1994-01-01

152

Quasisubharmonic vibrations in metal plates excited by high-power ultrasonic pulses  

Microsoft Academic Search

Strongly nonlinear vibration phenomena in metal plates excited by high-power ultrasonic pulses in different conditions are studied experimentally and theoretically. The experimental conditions for generating quasisubharmonics and subharmonics are found and discussed. The plate vibrations are characterized by waveforms, frequency spectra, pseudostate portraits, and Poincaré maps. Then, a three-degree-of-freedom vibroimpact-dynamic model is presented to explore the generation mechanisms of the

Zhao-Jiang Chen; Shu-Yi Zhang; Kai Zheng; Pao-Kuang Kuo

2009-01-01

153

Vibration energy harvesting via parametrically-induced bistability  

NASA Astrophysics Data System (ADS)

The dynamic response to white Gaussian noise of a bistable non-linear vibration energy harvester based on the repulsive electrostatic interaction between a microcantilever and an electrode has been theoretically studied. The cantilever-electrode system can be brought from a linear regime characterized by a quadratic potential, when cantilever is far from the electrode, to a non-linear bistable regime characterized by a quartic potential, when both elements are close enough. This distance parameter, which is commonly used to tune bistability, is unusually used here also to inject the energy to the system in the form of displacement noise. Thus, the widening and shifting to the low-frequency region of the response spectrum as well as the enhancement of the rms out-of-plane vibration of the cantilever are both demonstrated through this parametrically-induced bistability.

Abadal, G.; López, M.; Venstra, W. J.; Murillo, G.; Torres, F.

2014-11-01

154

Vibration–Translational Energy Transfer According to the Morse Potential  

Microsoft Academic Search

A quantum-mechanical analysis of molecular vibration–translational motion energy transfer is obtained using the Morse potential, a one-dimensional model, and the method of distorted waves. All wavefunctions and transition matrix elements are obtained in closed form. In the limit of high temperatures, the results are identical to the Landau–Teller expression. At low temperatures, resonances are found to result from the attractive

Samuel L. Thompson

1968-01-01

155

Exploring the vibrational fingerprint of the electronic excitation energy via molecular dynamics  

SciTech Connect

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.

Deyne, Andy Van Yperen-De; Pauwels, Ewald; Ghysels, An; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen, E-mail: karen.hemelsoet@ugent.be [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium)] [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium); De Meyer, Thierry [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium) [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium); Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium); De Clerck, Karen [Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium)] [Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium)

2014-04-07

156

Harvestable vibrational energy from an avian source: theoretical predictions vs. measured values  

NASA Astrophysics Data System (ADS)

For many reasons, it would be beneficial to have the capability of powering a wildlife tag over the course of multiple migratory seasons. Such an energy harvesting system would allow for more data collection and eliminate the need to replace depleted batteries. In this work, we investigate energy harvesting on birds and focus on vibrational energy harvesting. We review a method of predicting the amount of power that can be safely harvested from the birds such that the effect on their longterm survivability is not compromised. After showing that the safely harvestable power is significant in comparison to the circuits used in avian tags, we present testing results for the flight accelerations of two species of birds. Using these measured values, we then design harvesters that matched the flight acceleration frequency and are sufficiently low mass to be carried by the birds.

Shafer, Michael W.; MacCurdy, Robert; Garcia, Ephrahim; Winkler, David

2012-04-01

157

Repulsively driven frequency-increased-generators for durable energy harvesting from ultra-low frequency vibration.  

PubMed

An electromagnetic kinetic energy harvester has been developed, which can convert ultra-low-frequency motion and vibration energy into electrical power. This harvester employs a two-stage vibratory structure to collect low-frequency kinetic energy and effectively transfer it into electric power by using a pair of high-frequency resonant generators. Non-contact magnetic repulsive force is herein utilized for the 1st-stage sliding vibrator to drive the 2nd-stage resonators into frequency-up-conversion resonance. The non-contact actuation is helpful for durable and long-life working of the device. The prototyped device is fabricated and the design is well confirmed by experimental test. The harvester can be well operated at the frequency as low as 0.25 Hz. Under driving acceleration of 1 g at 0.5 Hz, the miniaturized harvester can generate a peak power of 4.42 mW and an average power of 158 ?W. PMID:24784650

Tang, Qiaochu; Yang, Yongliang; Li, Xinxin

2014-04-01

158

Step-up converter for electromagnetic vibrational energy scavenger  

E-print Network

This paper introduces a voltage multiplier (VM) circuit which can step up a minimum voltage of 150 mV (peak). The operation and characteristics of this converter circuit are described. The voltage multiplier circuit is also tested with micro and macro scale electromagnetic vibrational generators and the effect of the VM on the optimum load conditions of the electromagnetic generator is presented. The measured results show that 85% efficiency can be achieved from this VM circuit at a power level of 18 ?W.

Saha, C; Godsell, J; Carlioz, L; Wang, N; Mccloskey, P; Beeby, S; Tudor, J; Torah, Russel

2008-01-01

159

Skyrmion vibrational energies together with a generalized mass term  

SciTech Connect

We study various properties of a one-parameter mass term for the Skyrme model, originating from the works of Kopeliovich, Piette and Zakrzewski [V. B. Kopeliovich, B. Piette, and W. J. Zakrzewski, Phys. Rev. D 73, 014006 (2006).], through the use of axially symmetric solutions obtained numerically by simulated-annealing. These solutions allow us to observe asymptotic behaviors of the B=2 binding energies that differ to those previously obtained [B. Piette and W. J. Zakrzewski, Phys. Rev. D 77, 074009 (2008).]. We also decipher the characteristics of three distinct vibrational modes that appear as eigenstates of the vibrational Hamiltonian. This analysis further examine the assertion that the one-parameter mass term offers a better account of baryonic matter than the traditional mass term.

Davies, Merlin C.; Marleau, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec, G1K 7P4 (Canada)

2009-04-01

160

Electron-vibration energy exchange models in nitrogen-containing plasma flows  

SciTech Connect

The physics of vibrational kinetics in nitrogen-containing plasma produced by collisions with electrons is studied on the basis of recently derived cross sections and rate coefficients for the resonant vibrational-excitation by electron-impact. The temporal relaxation of the vibrational energy and of the vibrational distribution function is analyzed in a state-to-state approach. The electron and vibrational temperatures are varied in the range [0-50 000] K. Conclusions are drawn with respect to the derivation of reduced models and to the accuracy of a relaxation time formalism. An analytical fit of the vibrational relaxation time is given.

Laporta, V. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Istituto di Metodologie Inorganiche e dei Plasmi, CNR, 70125 Bari (Italy); Bruno, D. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, 70125 Bari (Italy)

2013-03-14

161

Field Telemetry of Blade-rotor Coupled Torsional Vibration at Matuura Power Station Number 1 Unit  

NASA Technical Reports Server (NTRS)

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.

Isii, Kuniyoshi; Murakami, Hideaki; Otawara, Yasuhiko; Okabe, Akira

1991-01-01

162

Optimized energy harvesting from mechanical vibrations through piezoelectric actuators, based on a synchronized switching technique  

NASA Astrophysics Data System (ADS)

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.

Tsampas, P.; Roditis, G.; Papadimitriou, V.; Chatzakos, P.; Gan, Tat-Hean

2013-05-01

163

Optimal design of a vibration-based energy harvester using magnetostrictive material (MsM)  

NASA Astrophysics Data System (ADS)

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.

Hu, J.; Xu, F.; Huang, A. Q.; Yuan, F. G.

2011-01-01

164

Vibrational wave functions and energy levels of large anharmonic clusters: A vibrational SCF study of (Ar)13  

NASA Astrophysics Data System (ADS)

The vibrational ground state and the fundamental excited states of (Ar)13 were studied by vibrational self-consistent field (VSCF) calculations. These calculations treat the interaction between different modes through a mean potential approximation, and incorporate anharmonicity in full. The good accuracy of VSCF for such systems was demonstrated by test calculations for (Ar)3 and other clusters. The study of (Ar)13 focused on the properties of the wave functions and the excitation energies, on the role of the coupling between the modes and on the deviation from the harmonic approximation. It was found that SCF excitation energies for the fundamental transitions differ from the harmonic values by about 25% for the softest modes, and by about 10% for the stiffest modes. Coupling between the modes, treated by SCF, was found to be much more important than the intrinsic anharmonicity of the individual modes. For the ground state, the harmonic wave function compares well with VSCF, but for the fundamental excited states appreciable differences were found. The results for a potential field expanded to fourth-order polynomial in the normal mode displacements are found to be valid, almost indentical with those for a more elaborate sixth-order polynomial expansion. The fundamental excitation frequencies computed using the Aziz-Slaman Ar-Ar pair potential are very similar, with some quantitative deviations, to the values obtained with a Lennard-Jones potential. The differences are larger for certain specific modes, and very small for the others. These calculations demonstrate the computational power of VSCF as a tool for quantum-mechanical calculations for large clusters, at the level of specific wave functions.

Jung, Joon O.; Gerber, R. Benny

1996-12-01

165

Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization  

NASA Technical Reports Server (NTRS)

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.

Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.

2014-01-01

166

Optimal piezoelectric beam shape for single and broadband vibration energy harvesting: Modeling, simulation and experimental results  

NASA Astrophysics Data System (ADS)

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.

Muthalif, Asan G. A.; Nordin, N. H. Diyana

2015-03-01

167

Electronic resonance with anticorrelated pigment vibrations drives photosynthetic energy transfer outside the adiabatic framework  

PubMed Central

The delocalized, anticorrelated component of pigment vibrations can drive nonadiabatic electronic energy transfer in photosynthetic light-harvesting antennas. In femtosecond experiments, this energy transfer mechanism leads to excitation of delocalized, anticorrelated vibrational wavepackets on the ground electronic state that exhibit not only 2D spectroscopic signatures attributed to electronic coherence and oscillatory quantum energy transport but also a cross-peak asymmetry not previously explained by theory. A number of antennas have electronic energy gaps matching a pigment vibrational frequency with a small vibrational coordinate change on electronic excitation. Such photosynthetic energy transfer steps resemble molecular internal conversion through a nested intermolecular funnel. PMID:23267114

Tiwari, Vivek; Peters, William K.; Jonas, David M.

2013-01-01

168

Vibration interaction in a multiple flywheel system  

NASA Astrophysics Data System (ADS)

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.

Firth, Jordan; Black, Jonathan

2012-03-01

169

Electrostatic vibration energy harvester with combined effect of electrical nonlinearities and mechanical impact  

NASA Astrophysics Data System (ADS)

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.

Basset, P.; Galayko, D.; Cottone, F.; Guillemet, R.; Blokhina, E.; Marty, F.; Bourouina, T.

2014-03-01

170

Modeling and Simulation of Linear and Nonlinear MEMS Scale Electromagnetic Energy Harvesters for Random Vibration Environments  

PubMed Central

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

Sassani, Farrokh

2014-01-01

171

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration  

NASA Technical Reports Server (NTRS)

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.

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

172

Vibration Analysis of Obstacle-avoidance for EHV Power Transmission Lines Inspection Robot  

Microsoft Academic Search

Research on the inspection robot for extra high voltage (EHV) power transmission lines focuses on their practical applications in the electric industry. Obstacle-avoidance plays a key in the inspection robot. When there is ambient interference, such as wind, a vibration is thereby occurred, which influences on the lines localization precision of the arm mechanism of the robot during the avoidance

Sun Cuilian; Wang Hongguang; Zhao Mingyang

2007-01-01

173

Analytical modeling and experimental verification of vibration-based piezoelectric bimorph beam with a tip-mass for power harvesting  

NASA Astrophysics Data System (ADS)

Power harvesting techniques that convert vibration energy into electrical energy through piezoelectric transducers show strong potential for powering smart wireless sensor devices in applications of structural health monitoring. This paper presents an analytical model of the dynamic behavior of an electromechanical piezoelectric bimorph cantilever harvester connected with an AC-DC circuit based on the Euler-Bernoulli beam theory and Hamiltonian theorem. A new cantilevered piezoelectric bimorph structure is proposed in which the plug-type connection between support layer and tip-mass ensures that the gravity center of the tip-mass is collinear with the gravity center of the beam so that the brittle fracture of piezoelectric layers can also be avoided while vibrating with large amplitude. The tip-mass is equated by the inertial force and inertial moment acting at the end of the piezoelectric bimorph beam based on D'Alembert's principle. An AC-DC converting circuit soldered with the piezoelectric elements is also taken into account. A completely new analytic expression of the global behavior of the electromechanical piezoelectric bimorph harvesting system with AC-DC circuit under input base transverse excitation is derived. Moreover, an experimental energy harvester is fabricated and the theoretical analysis and experimental results of the piezoelectric harvester under the input base transverse displacement excitation are validated by using measurements of the absolute tip displacement, electric voltage response, electric current response and electric power harvesting.

Wang, Hongjin; Meng, Qingfeng

2013-03-01

174

Vibration amplitude and induced temperature limitation of high power air-borne ultrasonic transducers.  

PubMed

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. PMID:23664304

Saffar, Saber; Abdullah, Amir

2014-01-01

175

A method for analyzing absorbed power distribution in the hand and arm substructures when operating vibrating tools  

NASA Astrophysics Data System (ADS)

In this study it was hypothesized that the vibration-induced injuries or disorders in a substructure of human hand-arm system are primarily associated with the vibration power absorption distributed in that substructure. As the first step to test this hypothesis, the major objective of this study is to develop a method for analyzing the vibration power flow and the distribution of vibration power absorptions in the major substructures (fingers, palm-hand-wrist, forearm and upper arm, and shoulder) of the system exposed to hand-transmitted vibration. A five-degrees-of-freedom model of the system incorporating finger- as well as palm-side driving points was applied for the analysis. The mechanical impedance data measured at the two driving points under four different hand actions involving 50 N grip-only, 15 N grip and 35 N push, 30 N grip and 45 N push, and 50 N grip and 50 N push, were used to identify the model parameters. The vibration power absorption distributed in the substructures were evaluated using vibration spectra measured on many tools. The frequency weightings of the distributed vibration power absorptions were derived and compared with the weighting defined in ISO 5349-1 (2001). This study found that vibration power absorption is primarily distributed in the arm and shoulder when operating low-frequency tools such as rammers, while a high concentration of vibration power absorption in the fingers and hand is observed when operating high-frequency tools, such as grinders. The vibration power absorption distributed in palm-wrist and arm is well correlated with the ISO-weighted acceleration, while the finger vibration power absorption is highly correlated with unweighted acceleration. The finger vibration power absorption-based frequency weighting suggested that exposure to vibration in the frequency range of 16-500 Hz could pose higher risks of developing finger disorders. The results support the use of the frequency weighting specified in the current standard for assessing risks of developing disorders in the palm-wrist-arm substructures. The standardized weighting, however, could overestimate low-frequency effects but greatly underestimate high-frequency effects on the development of finger disorders. The results are further discussed to show that the trends observed in the vibration power absorptions distributed in the substructures are consistent with some major findings of various physiological and epidemiological studies, which provides a support to the hypothesis of this study.

Dong, Jennie H.; Dong, Ren G.; Rakheja, Subhash; Welcome, Daniel E.; McDowell, Thomas W.; Wu, John Z.

2008-04-01

176

Efficiency improvement in a vibration power generator for a linear MR damper: numerical study  

NASA Astrophysics Data System (ADS)

This paper summarizes a numerical analysis of the electromagnetic field, voltage and circuit properties and the cogging force in a vibration power generator comprising permanent magnets and a coil with a foil winding. The device converts the energy harvested from vibrations into electrical energy which is next used to vary the damping characteristics of a linear MR damper attached to the generator. The objective of the study is to propose a sufficiently efficient generator whose finally developed (target) version could be integrated with a small-scale MR damper to build a single device. Two design options for the device are numerically studied, the previously engineered generator 1 and the newly devised generator 2. Generator 1 incorporates two magnet systems having four magnets each and a single-section coil, while generator 2 comprises three magnet systems with four magnets each and a two-section coil. Calculations were performed to determine the electromagnetic field, voltage and current properties and the cogging force in the generators. The electromagnetic field parameters include the distribution of the magnetic field, the electrical potential field and the current density in the open turn and closed turn of the generators’ coils. The voltage and current properties include electromotive force (emf) in the generators and the voltage, current, instantaneous power and energy of the magnetic field in the MR damper control coil which is represented by resistance parameter R and inductance parameter L. The cogging force expresses the magnetic interactions between the permanent magnet systems and ferromagnetic structural components of the generators. The occurrence of this force is very unfavourable and attempts should be made to reduce it through control of the parameters of the magnetic circuit components. On one hand, comparison of the numerical results for the electromagnetic field parameters and voltage and current properties revealed that for the predetermined RL parameters of the MR damper control coil, generator 2 seems to be more efficient than generator 1 and hence is more suitable for supplying the MR damper. On the other hand, comparison of the calculated cogging force levels revealed that its value tends to be lower in generator 1. It is reasonable to suppose that development of a final version of the generator with the defined structure and enhanced efficiency would have to involve some trade-off between the emf and the cogging force.

Sapi?ski, Bogdan; Krupa, Stanis?aw

2013-04-01

177

Energy-dependent characteristics of collisinal vibration-energy exchange in vapors of polyatomic molcules  

SciTech Connect

CO{sub 2} laser-induced delayed fluorescence was used to study the collisional vibration-energy exchange between the polyatomic molecules in gases. The efficiency of collisional exchange, the mean amount of energy transfer in one collision, as well as their correlation with the vibration energy and with the size of excited molecule were determined for diacetyl, acetophenone, benzophenone, and anthraquinone molecules form the experimentally observed pressure dependences of the decay rates and fluorescence intensities. It was shown that the mean amount of energy transfer per collision decreases with the molecular size and increases as E{sup m}, with m>2, with increasing the vibration energy. 25 refs., 4 figs., 1 tab.

Zalesskaya, G.A.; Yakovlev, D.L. [Institute of Molecular and Atomic Physics, Minsk (Belarus)

1995-02-01

178

Vibration energy harvesting using a phononic crystal with point defect states  

NASA Astrophysics Data System (ADS)

A vibration energy harvesting generator was studied in the present research using point-defect phononic crystal with piezoelectric material. By removing a rod from a perfect phononic crystal, a resonant cavity was formed. The elastic waves in the range of gap frequencies were all forbidden in any direction, while the waves with resonant frequency were localized and enhanced in the resonant cavity. The collected vibration energy was converted into electric energy by putting a polyvinylidene fluoride film in the middle of the defect. This structure can be used to simultaneously realize both vibration damping and broad-distributed vibration energy harvesting.

Lv, Hangyuan; Tian, Xiaoyong; Wang, Michael Yu; Li, Dichen

2013-01-01

179

POWER EVALUATION FOR FLUTTER-BASED ELCTROMAGNETIC ENERGY HARVESTER USING CFD SIMULATIONS  

E-print Network

to generate power (Allen and Smits 2001; Sun et al. 2011) and to generate inductance power in electromagneticPOWER EVALUATION FOR FLUTTER-BASED ELCTROMAGNETIC ENERGY HARVESTER USING CFD SIMULATIONS J. Park 1-shape cantilever causes periodic vibration, which can be converted into electric power through an electromagnetic

Stanford University

180

A donor-acceptor pair for the real time study of vibrational energy transfer in proteins.  

PubMed

Vibrational energy transfer (VET) is believed to play an important role in protein function. Theoretical studies predict highly directional, anisotropic VET in proteins. Distinct energy transfer pathways which connect distant functional sites in proteins have been proposed by simulations, indicating a function in allosteric communication. Experimental evidence for such pathways, however, is lacking. In small molecules, ultrafast vibrational pump-probe spectroscopy has been used to investigate VET between different parts of a molecule in great detail. Here, we address the requirements for extending this powerful approach to proteins and present a protein-compatible donor-acceptor pair for the real time investigation of VET. This VET pair consists of two non-native amino acids, ?-(1-azulenyl)-alanine and azidohomoalanine, which can be positioned site-specifically and are found to be very well suited for spectroscopic studies of VET. Important for the study of proteins, co-translational incorporation of each of the amino acids has been demonstrated before using mutually independent approaches of protein engineering. We investigated the performance of the proposed VET pair in a model peptide which is designed to contain additional characteristic vibrational modes frequently used in infrared spectroscopy of proteins. Despite a larger inter-residue distance, we find that our VET acceptor generates a major signal that is easily observed compared to the other vibrational modes in the congested parts of the spectrum. We find sufficient signal size at concentrations compatible with proteins and over distances that will allow tracking of energy flow along predicted transfer pathways. PMID:24413252

Müller-Werkmeister, Henrike M; Bredenbeck, Jens

2014-02-21

181

Isotopically selective collisional vibrational energy transfer in CF3H.  

PubMed

The authors investigate here the mechanism of collisionally enhanced isotopic selectivity observed in infrared multiple photon dissociation (IRMPD) of vibrationally preexcited CF3H by Boyarkin et al. [J. Chem. Phys. 118, 93 (2003)]. For both the carbon-12 and carbon-13 isotopic species they measure the dependence of the IRMPD yield on the time delay between the preexcitation and the dissociation pulses at different dissociation frequencies as well as its dependence on the initial isotopic composition of the sample. The results reveal that the collisional increase in isotopic selectivity originates not only from that of IRMPD itself but also from the isotopic selectivity of vibrational energy transfer, with the latter making the major contribution under their experimental conditions. They suggest that the observed isotopic selectivity in collisional energy transfer arises from the difference in overlap between the absorption spectra of the nu5 mode in the 12CF3H acceptor molecule with emission spectra of the same mode in the two isotopically different donors. Understanding the origin of this collisional effect has important implications for optimization of laser isotope separation processes. PMID:17302472

Bossart, R; Boyarkin, O V; Makarov, A A; Rizzo, T R

2007-02-01

182

Adhesion energy characterization of monolayer graphene by vibrational spectroscopy  

NASA Astrophysics Data System (ADS)

As at nano/micro-scale van der Waals forces often dominate various other types of forces, the accurate adhesion characterization of graphene (Gr) is essential to its processing, manipulation, and possible integration into integrated circuits and other nano/micro-scale devices. Since 2010, the reported (experimental) adhesion energy of monolayer Gr with silicon dioxide (SiO2) has increased from 151 ± 28 mJ/m2 to 450 ± 20 mJ/m2. Here, we report a set of adhesion energy values for Gr monolayers on a SiO2 substrate by adopting a unique vibrational spectroscopy approach based on the motion of adhesive microparticles on a vibrating substrate. The reported results indicate that the work-of-adhesion measurements of monolayer Gr on SiO2 could be highly scattered and its mean value is determined as WSiO2-Gr = 1160.26 mJ/m2, which is the highest value reported to date. Unlike the reported existing methods, the current non-contact and non-destructive spectral technique requires no knowledge of the mechanical properties of Gr. Based on the reported data, with the current approach, it is also demonstrated that the weak adhesive interactions between a polystyrene latex microparticle and SiO2 substrate across the monolayer Gr can be detected as well.

Vahdat, Armin Saeedi; Cetinkaya, Cetin

2013-10-01

183

Determination of stepsize parameters for intermolecular vibrational energy transfer  

SciTech Connect

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.

Tardy, D.C.

1992-03-01

184

Power management for energy harvesting wireless sensors  

NASA Astrophysics Data System (ADS)

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.

Arms, S. W.; Townsend, C. P.; Churchill, D. L.; Galbreath, J. H.; Mundell, S. W.

2005-05-01

185

Molecular dynamics simulation of vibrational energy relaxation of highly excited molecules in fluids. III. Equilibrium simulations of vibrational energy relaxation of azulene in carbon dioxide  

NASA Astrophysics Data System (ADS)

The expressions for vibrational energy relaxation (VER) rates of polyatomic molecules in terms of equilibrium capacity time correlation functions (TCFs) derived in the first paper of this series [J. Chem. Phys. 110, 5273 (1999)] are used for the investigation of VER of azulene in carbon dioxide at low (3.2 MPa) and high (270 MPa) pressure. It is shown that for both cases the VER times evaluated on the basis of the same potential model via solute-solvent interaction capacity TCFs by means of equilibrium molecular dynamics (EMD) simulations satisfactorily agree with the nonequilibrium (NEMD) molecular dynamics [J. Chem. Phys. 110, 5286 (1999)] and experimental [J. Chem. Phys. 105, 3121 (1996)] results as well. Thus it follows that these methods can complement each other in characterizing VER from different points of view. Although more computational power and refined methods of dealing with simulated data are required for EMD simulations, they allow the use of powerful tools of equilibrium statistical mechanics for investigating the relaxation process. To this end, an analysis of VER mechanisms on the basis of normal mode and atomic representations is carried out. The influence of temperature and CO2 pressure on azulene normal mode spectra and solvent assisted intermode coupling in connection with the eigenvector structure is investigated in great detail. The normal mode capacity cross-correlation matrix reveals the significance of intermode coupling, which significantly contributes to intramolecular vibrational energy redistribution (IVR). As a new concept, partial normal mode relaxation rates are introduced. It is shown that these rates demonstrate similar properties as the energy exchange rates through particular normal modes in nonequilibrium simulations. Atomic spectra and friction coefficients are characterized by a complicated frequency dependence due to contributions from many normal modes. Atomic capacity TCFs and partial relaxation rates are analyzed and reveal a similar picture to that obtained from NEMD simulations. These results show that VER and IVR cannot be separated from each other and have to be considered as mutually connected processes.

Heidelbach, C.; Vikhrenko, V. S.; Schwarzer, D.; Fedchenia, I. I.; Schroeder, J.

1999-11-01

186

Piezoelectric energy harvesting from vortex-induced vibrations of circular cylinder  

NASA Astrophysics Data System (ADS)

The concept of harvesting energy from a circular cylinder undergoing vortex-induced vibrations is investigated. The energy is harvested by attaching a piezoelectric transducer to the transverse degree of freedom. Numerical simulations are performed for Reynolds numbers (Re) in the range 96?Re?118, which covers the pre-synchronization, synchronization, and post-synchronization regimes. Load resistances (R) in the range 500 ??R?5 M? are considered. The results show that the load resistance has a significant effect on the oscillation amplitude, lift coefficient, voltage output, and harvested power. The results also show that the synchronization region widens when the load resistance increases. It is also found that there is an optimum value of the load resistance for which the harvested power is maximum. This optimum value does not correspond to the case of largest oscillations, which points to the need for a coupled analysis as performed here.

Mehmood, A.; Abdelkefi, A.; Hajj, M. R.; Nayfeh, A. H.; Akhtar, I.; Nuhait, A. O.

2013-09-01

187

Vibration-vibration and vibration-translation energy transfer in H2-H2 collisions: A critical test of experiment with full-dimensional quantum dynamics  

NASA Astrophysics Data System (ADS)

Quantum scattering calculations of vibration-vibration (VV) and vibration-translation (VT) energy transfer for non-reactive H2-H2 collisions on a full-dimensional potential energy surface are reported for energies ranging from the ultracold to the thermal regime. The efficiency of VV and VT transfer is known to strongly correlate with the energy gap between the initial and final states. In H2(v = 1, j = 0) + H2(v = 0, j = 1) collisions, the inelastic cross section at low energies is dominated by a VV process leading to H2(v = 0, j = 0) + H2(v = 1, j = 1) products. At energies above the opening of the v = 1, j = 2 rotational channel, pure rotational excitation of the para-H2 molecule leading to the formation of H2(v = 1, j = 2) + H2(v = 0, j = 1) dominates the inelastic cross section. For vibrationally excited H2 in the v = 2 vibrational level colliding with H2(v = 0), the efficiency of both VV and VT process is examined. It is found that the VV process leading to the formation of 2H2(v = 1) molecules dominates over the VT process leading to H2(v = 1) + H2(v = 0) products, consistent with available experimental data, but in contrast to earlier semiclassical results. Overall, VV processes are found to be more efficient than VT processes, for both distinguishable and indistinguishable H2-H2 collisions confirming room temperature measurements for v = 1 and v = 2.

dos Santos, S. Fonseca; Balakrishnan, N.; Forrey, R. C.; Stancil, P. C.

2013-03-01

188

Vibration excitation and energy transfer during ultrasonically assisted drilling  

NASA Astrophysics Data System (ADS)

Successful application of ultrasonically assisted drilling needs dynamic matching of the transducer with the drill bit considered as a continuous system loaded by the nonlinear processing load. When using standard tools this leads to the compatible choice of the transducer and accurate matching of the transducer and tool. The principal dynamical features of this matching are considered. Optimal position of excitation cross section of the drill bit, which depends on the relationship between elasto-dissipative characteristics of the transducer, the drill bit and the work load, is found in general analytical form. The optimal matching preserves the resonant tuning of the transducer and compensates the additional energy losses in the drill bit and processing. This produces also an amplification of vibration amplitude. The effect is achieved through the generation and maintenance of a nonlinear resonant mode of vibration and by active matching of the oscillating system with the dynamic loads imposed by the cutting process with the help of the intelligent electronic feedback circuitry. A prototype of an ultrasonic drilling system has been designed, manufactured. and tested. Improvements of machining characteristics due to superposition of ultrasonic vibration are demonstrated. Substantial improvements in the cutting performance of drill bits lead to benefits in drilling performance, which include faster penetration rates, reduction of tool wear, improvements in the surface finish, roundness and straightness of holes and, in ductile materials, the reduction or even complete elimination of burrs on both the entrance and exit faces of plates. The reduction in the reactive force experienced also causes greatly reduced deformation when drilling through thin, flexible plates and helps to alleviate delamination hazard.

Babitsky, V. I.; Astashev, V. K.; Meadows, A.

2007-12-01

189

A Control Method Switching from Vibration Reduction to Positioning for Power Assisted Moving Flexible Structures  

NASA Astrophysics Data System (ADS)

This paper shows control methods of the smooth switching from vibration reduction when a worker conveys flexible structures to their positioning. One of the important issues in this study is there are no knowledge of the goal position before conveying an object and the terminal time when worker finishes conveying. Then one of sensors can detect the displacement of the object not anytime but only the time when the position is settled. Additionally, an overshoot has to be prevented when there are other objects at the goal position. For clearing up these issues, we applied an adaptive nonstationary control method and showed its effectiveness. And two methods for determining the goal position with limited sensor signals are proposed. For showing the utility of the proposed methods, we conducted four kinds of experiments of positioning a flexible object: 1) only the power assist control, 2) the vibration control with power assist control, 3) the vibration and position control with power assist control and laser sensor, 4) the vibration and position control with power assist control without laser sensor. The results show that the first method is useful for accurate positioning in a short time. The second method does not need an additional sensor used in the first method. However, this method takes a longer time for accurate positioning settling. Adaptive nonstationary control with smooth mode switching is useful when the additional sensor signal is input in the positioning stage only. Then, the results also show that vibration control is important when not only conveying but also positioning because of preventing the overshoot. The proposed methods are useful because it can position any undetermined goal position before conveying.

Fujimoto, Isao; Hara, Susumu; Yamada, Yoji; Morita, Yoshifumi; Seshimo, Kiyoshi; Higashi, Masatake

190

Operation Assist by Vibration Suppression Control Using Impulse Shaped Signals for Power Assist Type Conveyance System  

NASA Astrophysics Data System (ADS)

This paper presents an assist control method for flexible parts conveyance task using power assist type conveyance system. The assist control method should be designed so as to not only suppress the vibration but also reduce degradation of operating feel. For this purpose, multiple impulse shaped signals are used as feedforward signals in order to reduce the vibration of flexible parts during conveyance. In addition, adjustment time is introduced to adjust input timing of impulse shaped signal and to suppress vibration. Moreover, in order to improve the degradation of operating feel, the smaller amplitudes of the three impulse shaped signals are used and input repeatedly. The effectiveness of the proposed system was verified experimentally.

Yamamoto, Yuichi; Uchida, Masaki; Morita, Yoshifumi; Hara, Susumu

191

Design considerations for small-scale wind energy harvesters driven by broadband vortex-induced vibrations  

NASA Astrophysics Data System (ADS)

In recent years, an increasing number of breakthroughs have been made in the field of small-scale wind energy harvesting, where specialized materials are utilized to convert flow energy into electric power. Several studies on this power extraction rely on a common energy harvester setup in which a stiff cantilever beam is attached to the trailing edge of a miniature bluff body. At these small scales where boundary layer effects are appreciable in the laminar flow regime, periodic vortex shedding can be used to drive transverse vibrations in the beam. Interestingly, the fluid dynamics involved in this unsteady process have been studied for decades not to exploit their characteristics, but instead to eliminate potentially destructive effects. As a result, there is still much room for improvement and expansion on recent design studies. A study of how subtle changes in bluff body trailing edge geometry effect power output of a model will be presented in this paper. The model under consideration consists of a miniature bluff body on the order of tens of millimeters in diameter, to which a piezoelectric cantilever is attached at the trailing edge. This model is specifically designed for laminar to transitional Reynolds Number flows (500-2800) where the periodicity of vortex shedding approaches the natural frequency of the beam. As the flow speed is further increased, the effect of lock-in occurs where the resonant beam motion resists a change in vortex shedding frequency. Vibration amplitudes of the beam reach a maximum under this condition, thus maximizing power generation efficiency of the system and providing an optimal condition to operate the harvester. In an effort to meaningfully compare the results, a number of dimensionless parameters are employed. The influence of parameters such as beam length and natural frequency, fluid flow speed, and trailing edge geometry are studied utilizing COMSOL Multiphysics laminar, fluid-structure interaction simulations in order to create design guidelines for an improved energy harvester.

Paxson, Benjamin; Wickenheiser, Adam M.

2014-04-01

192

The Power of Energy Storage  

E-print Network

The Power of Energy Storage How to Increase Deployment in California to Reduce Greenhouse Gas;1Berkeley Law \\ UCLA Law The Power of Energy Storage: How to Increase Deployment in California to Reduce Greenhouse Gas Emissions Executive Summary: Expanding Energy Storage in California Sunshine and wind, even

Sadoulet, Elisabeth

193

Energy 101: Concentrating Solar Power  

ScienceCinema

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.

None

2013-05-29

194

Energy 101: Concentrating Solar Power  

SciTech Connect

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.

None

2010-01-01

195

Broadband electromagnetic power harvester from vibrations via frequency conversion by impact oscillations  

NASA Astrophysics Data System (ADS)

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 ?W was achieved at 5 g at 30 Hz across a load resistor, 2.68 ?.

Yuksek, N. S.; Feng, Z. C.; Almasri, M.

2014-09-01

196

Broadband electromagnetic power harvester from vibrations via frequency conversion by impact oscillations  

SciTech Connect

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??W was achieved at 5?g at 30?Hz across a load resistor, 2.68 ?.

Yuksek, N. S.; Almasri, M. [Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65211 (United States); Feng, Z. C. [Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri 65211 (United States)

2014-09-15

197

Time scale considerations on the relaxation of electronic and vibrational energy distributions in a nitrogen afterglow (+)  

E-print Network

L-251 Time scale considerations on the relaxation of electronic and vibrational energy plus signibcatifs. Les résultats du calcul montrent que les collisions électroniques sur l of the electron energy distribution function (edf) in vibrationally excited N2 post discharges has been analysed

Boyer, Edmond

198

Reaction of formaldehyde cation with methane: Effects of collision energy and methane vibrations  

E-print Network

Reaction of formaldehyde cation with methane: Effects of collision energy and H2CO¿ and methane, Salt Lake City, Utah 84112 Received 20 February 2003; accepted 3 April 2003 The effects on the title reaction of collision energy (Ecol), five H2CO vibrational modes, and deformation vibrations of methane

Anderson, Scott L.

199

Mode-specific energy analysis for rotating-vibrating triatomic molecules in classical trajectory simulation  

E-print Network

Mode-specific energy analysis for rotating-vibrating triatomic molecules in classical trajectory A method for the mode-specific energy analysis in a classical trajectory calculation is developed. The pure normal mode, the vibrational velocity is divided into two parts, the angular motion part and the angular

Kim, Myung Soo

200

Investigation of effect of reduction of valve friction in a power control system by use of a vibrator  

NASA Technical Reports Server (NTRS)

Brief ground tests were made to determine the effect of reduction of valve friction in a power control system of a fighter airplane by use of a vibrator. The vibrator was found to be an effective means of overcoming adverse effects of valve friction on the control characteristics.

Phillips, William H

1955-01-01

201

Measurements of mechanical vibrations at magnetic cores of power transformers with fiber-optic interferometric intrinsic sensor  

Microsoft Academic Search

A fiber-optic interferometric sensor with intrinsic transducer along a length of the fiber is presented for vibration measurements of the magnetic core inside an oil-filled power transformer. The sensor is designed for high sensitivity measurements into the harsh environment of electromagnetic fields, wide temperature change, and in oil immersing. This sensor allows enough sensitivity for the application, for which vibrations

Horatio Lamela Rivera; Jose A. García-Souto; J. Sanz

2000-01-01

202

Correct Prediction of the Vibration Behavior of the High Power Ultrasonic Transducers by Fem Simulation  

Microsoft Academic Search

High power ultrasound is nowadays used in a wide variety of applications ranging from medical devices, ultrasonic cleaning,\\u000a ultrasonic welding and machining to sonochemistry [1]. Since Prof. Langevin developed the first sandwich ultrasonic transducer by embedding piezoelectric rings between two metals\\u000a and employed it for high intensity vibration, there have been great efforts in modeling and formulating such transducers [2–5].

Abbas Pak; Amir Abdullah

203

Vibration-to-electric energy conversion using a mechanically-varied capacitor  

E-print Network

Past research in vibration energy harvesting has focused on the use of variable capacitors, magnets, or piezoelectric materials as the basis of energy transduction. How- ever, few of these studies have explored the detailed ...

Yen, Bernard Chih-Hsun, 1981-

2005-01-01

204

Green vehicle shock absorber: Micromachined wavy shaped piezoelectric cushion energy harvester and its power generating demonstration based on real navigation  

Microsoft Academic Search

The paper presents a novel micromachined piezoelectric cushion power generator which harvests vibration energy from the vehicle shock absorber. The developed transducer demonstrates the feasibility of the concept of Green vehicle shock absorber. Two major components are involved in implementation of the device: a wavy shaped PVDF film for scavenging vibration energy and an elastic PDMS cushion for damping the

Guo-Hua Feng; Min-Yiang Tsai

2011-01-01

205

Vibrational excitation of adsorbed molecules by photoelectrons of very low energy: acrylonitrile on Cu(100).  

PubMed

In this study, we report on a powerful method of primary photoelectron scattering by adsorbed species. Specifically, threshold-energy (E(kin,max) < 0.5 eV) two-photon photoelectrons (2PPE) are used to probe acrylonitrile (ACN) molecules chemisorbed onto a Cu(100) substrate, held at room temperature. This has proven to constitute a perfect tool to reveal the ACN vibrational modes in the chemisorbed state. From the dynamics of the directional (perpendicular to the copper surface) electron energy loss we conclude that only a few fundamental vibrational motions of adsorbed ACN are excited, namely the C=C, C?N and C-H stretch modes. From the excitation probability spectra threshold energies, E(th), of these modes was extracted: E(th)(C=C) = 182(15) meV, E(th)(C?N) = 248(16) meV--which are shifted noticeably from the equivalent gas phase values; and E(th)(C-H) ?360-380 meV--which varies only marginally from the gas phase value. The interpretation of the excitation spectra suggests that the di-? adsorption configuration of the terminal C- and N-atoms dominates, which agrees well with the orientation and bindings predicted in Density Functional Theory (DFT) calculations. Consistent with this is the observation that the contribution to the 2PPE excitation spectra from the C-H stretch motion is by far the largest, which are not directly affected by chemisorption bonding. PMID:21399839

Tornero, J; Telle, H H; García, G; González Ureña, A

2011-05-14

206

Global Nonlinear Analysis of Piezoelectric Energy Harvesting from Ambient and Aeroelastic Vibrations  

NASA Astrophysics Data System (ADS)

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 effects of the linear spring coefficients and electrical load resistance on the flutter speed. Then, the normal form of the Hopf bifurcation ( utter) is derived to characterize the type of instability and determine the effects of the aerodynamic nonlinearities and the nonlinear coefficients of the springs on the system's stability near the bifurcation. This is useful to characterize the effects of different parameters on the system's output and ensure that subcritical or "catastrophic" bifurcation does not take place. Both linear and nonlinear analyses are then used to design and enhance the performance of these harvesters. In the last part, the concept of energy harvesting from vortex-induced vibrations of a circular cylinder is investigated. The power levels that can be generated from these vibrations and the variations of these levels with the freestream velocity are determined. A mathematical model that accounts for the coupled lift force, cylinder motion and generated voltage is presented. Linear analysis of the electromechanical model is performed to determine the effects of the electrical load resistance on the natural frequency of the rigid cylinder and the onset of the synchronization region. The impacts of the nonlinearities on the cylinder's response and energy harvesting are then investigated.

Abdelkefi, Abdessattar

207

Motion characteristics and output voltage analysis of micro-vibration energy harvester based on diamagnetic levitation  

NASA Astrophysics Data System (ADS)

In this paper, the force analysis and output performance of the micro-vibration energy harvester are elaborated. The force of the floating magnet in the magnetic field of the lifting magnet is firstly analyzed. Using COMSOL™, the change of magnetic force exerted on the floating magnet versus the vertical distance and the horizontal eccentric distance is obtained for different lifting magnets of a cylinder, a ring and an inner cylinder plus an outer ring, respectively. When the distance between the lifting and floating magnets ranges from 7.3 to 8.1 mm, the change rate of the magnetic force versus the vertical distance for the inner cylinder plus outer ring structure is the smallest, whose value is 619 µN/mm. In other words, if the inner cylinder plus outer ring structure is used as the lifting magnet, the vibration space of the floating magnet is the largest, which is 8 and 7.6 % larger than the cylinder and ring lifting magnets, respectively. The horizontal restoring forces of the three structures are substantially equal to each other at the horizontal eccentric distance of 4 mm, which is around 860 µN. Then the equilibrium position change of the floating magnet is discussed when the energy harvester is in an inclined position. Finally, by the analysis of the vibration model, the output performances of the energy harvester are comparatively calculated under the vertical and inclined positions. At the natural frequency of 6.93 Hz, the maximum power of 66.7 µW is generated.

Ye, Zhitong; Duan, Zhiyong; Takahata, Kenichi; Su, Yufeng

2015-01-01

208

Motion characteristics and output voltage analysis of micro-vibration energy harvester based on diamagnetic levitation  

NASA Astrophysics Data System (ADS)

In this paper, the force analysis and output performance of the micro-vibration energy harvester are elaborated. The force of the floating magnet in the magnetic field of the lifting magnet is firstly analyzed. Using COMSOL™, the change of magnetic force exerted on the floating magnet versus the vertical distance and the horizontal eccentric distance is obtained for different lifting magnets of a cylinder, a ring and an inner cylinder plus an outer ring, respectively. When the distance between the lifting and floating magnets ranges from 7.3 to 8.1 mm, the change rate of the magnetic force versus the vertical distance for the inner cylinder plus outer ring structure is the smallest, whose value is 619 µN/mm. In other words, if the inner cylinder plus outer ring structure is used as the lifting magnet, the vibration space of the floating magnet is the largest, which is 8 and 7.6 % larger than the cylinder and ring lifting magnets, respectively. The horizontal restoring forces of the three structures are substantially equal to each other at the horizontal eccentric distance of 4 mm, which is around 860 µN. Then the equilibrium position change of the floating magnet is discussed when the energy harvester is in an inclined position. Finally, by the analysis of the vibration model, the output performances of the energy harvester are comparatively calculated under the vertical and inclined positions. At the natural frequency of 6.93 Hz, the maximum power of 66.7 µW is generated.

Ye, Zhitong; Duan, Zhiyong; Takahata, Kenichi; Su, Yufeng

2014-08-01

209

A distributed parameter electromechanical and statistical model for energy harvesting from turbulence-induced vibration  

NASA Astrophysics Data System (ADS)

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.

Hobeck, J. D.; Inman, D. J.

2014-11-01

210

Reliability of vibration energy harvesters of metal-based PZT thin films  

NASA Astrophysics Data System (ADS)

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 ?m) 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.

Tsujiura, Y.; Suwa, E.; Kurokawa, F.; Hida, H.; Kanno, I.

2014-11-01

211

ESTIMATING DAMPING PARAMETERS IN MULTI-DEGREE-OF-FREEDOM VIBRATION SYSTEMS BY BALANCING ENERGY0  

E-print Network

motility response [22]. These techniques can produce modal damping in multi- degree-of-freedom (MDOFESTIMATING DAMPING PARAMETERS IN MULTI-DEGREE-OF-FREEDOM VIBRATION SYSTEMS BY BALANCING ENERGY0 B@egr.msu.edu ABSTRACT A method of estimating damping parameters for multi- degree-of-freedom vibration systems

Feeny, Brian

212

Vibration Exercise as a Warm-up Modality for Deadlift Power Output.  

PubMed

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 prior to 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. The DL warm-up included 10, 8, and 5 repetitions performed at 30%, 40%, and 50% 1 repetition maximum (RM), respectively, where the number of repetitions was matched by body weight squats performed with vibration and without vibration (Control). The warm-up conditions were randomised and performed at least 2 days apart. Peak power, mean power, rate of force development, and electromyography (EMG) were measured during the concentric phase of two consecutive deadlifts (75% 1 RM) at 30 s and 2:30 min following the warm-up conditions. There was no significant (p > 0.05) main effect or interaction effect between the DL warm-up, VbX warm-up and Control for peak power, mean power, rate of force development, and EMG. VbX warm-up did not exhibit an ergogenic effect to potentiate muscle activity more than the specific deadlift warm-up 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. PMID:25353078

Cochrane, Darryl J; Coley, Karl W; Pritchard, Hayden J; Barnes, Matthew J

2014-10-28

213

ENERGY EFFICIENCY RESEARCH POWERS  

E-print Network

Californiaratepayers,theEnergy Commissionimplementedthecountry'sfirstenergyeffi- ciencybuildingandappliancestandardsin1978.Theregu- lationsinCalifornia'sAppliance incorporated into the building and appliance stan- dards. This included research on television energy use, externalpowersupplies,batterychargers,residentialfur- nacefans,coolroofsforhomes,homeatticducts,kitchen

214

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. Part 3: Sinusoidal and random vibration data reduction and evaluation, and random vibration probability analysis  

NASA Technical Reports Server (NTRS)

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.

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

215

A hybrid electromagnetic energy harvesting device for low frequency vibration  

NASA Astrophysics Data System (ADS)

An electromagnetic energy harvesting device, which converts a translational base motion into a rotational motion by using a rigid bar having a moving mass pivoted on a hinged point with a power spring, has been recently developed for use of civil engineering structures having low natural frequencies. The device utilizes the relative motion between moving permanent magnets and a fixed solenoid coil in order to harvest electrical power. In this study, the performance of the device is enhanced by introducing a rotational-type generator at a hinged point. In addition, a mechanical stopper, which makes use of an auxiliary energy harvesting part to further improve the efficiency, is incorporated into the device. The effectiveness of the proposed hybrid energy harvesting device based on electromagnetic mechanism is verified through a series of laboratory tests.

Jung, Hyung-Jo; Kim, In-Ho; Min, Dong Yi; Sim, Sung-Han; Koo, Jeong-Hoi

2013-04-01

216

Harvesting broadband kinetic impact energy from mechanical triggering/vibration and water waves.  

PubMed

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 ?A, 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. PMID:24964297

Wen, Xiaonan; Yang, Weiqing; Jing, Qingshen; Wang, Zhong Lin

2014-07-22

217

The effects of whole-body vibration on the Wingate test for anaerobic power when applying individualized frequencies.  

PubMed

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. PMID:24378660

Surowiec, Rachel K; Wang, Henry; Nagelkirk, Paul R; Frame, Jeffrey W; Dickin, D Clark

2014-07-01

218

The Power of Energy  

NSDL National Science Digital Library

Have you ever wondered how energy changes from one form to another? How you can put food in microwave, and seconds later it is hot? What happens between the time you plug in a TV and you see a picture? Students will take a deeper look into energy. What are all of the kinds of energy that help an object work? This lesson is a fun way to involve kids in their learning and include technology to present.

Diana Congden

2012-06-14

219

Renewable Energy Powers Renewable Energy Lab, Employees  

E-print Network

. NREL is also using solar energy for auxiliary purposes such as powering streetlights, water pumps and the lab's new entrance sign. An experimental 12-kilowatt rooftop solar system also feeds electricity back

220

Energy 101: Concentrating Solar Power  

NSDL National Science Digital Library

This video describes how concentrating solar power (CSP) technologies reflect and collect solar energy to generate electricity. This video explains what CSP is, how it works, and focuses on parabolic troughs.

National Renewable Energy Laboratory (NREL)

221

Origin of Low-Energy Quadrupole Collectivity in Vibrational Nuclei H. Fujita,2,3  

E-print Network

Origin of Low-Energy Quadrupole Collectivity in Vibrational Nuclei C. Walz,1 H. Fujita,2,3 A is a separation of energy (respectively momentum) scales such that the high-energy degrees of freedom) energy scale. In the IBM the relevant low-energy degrees of freedom for the description of quadrupole

Ponomarev, Vladimir

222

Energy, A Crisis in Power.  

ERIC Educational Resources Information Center

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

Holdren, John; Herrera, Philip

223

Vibration-translation energy transfer in anharmonic diatomic molecules. 2: The vibrational quantum number dependence  

NASA Technical Reports Server (NTRS)

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.

Mckenzie, R. L.

1975-01-01

224

Influence of hand forces and handle size on power absorption of the human hand arm exposed to zh-axis vibration  

NASA Astrophysics Data System (ADS)

The effect of handle size and hand forces, on the power absorbed by the hand-arm system, was investigated in a laboratory study using seven healthy male subjects exposed to two levels of broadband random vibration in the 8-1000 Hz frequency range along the zh-axis. The measurements were performed with three instrumented cylindrical handles of different diameter (30, 40 and 50 mm). The influence of hand forces applied by the subjects holding the vibrating handles was investigated under nine different grip/push force combinations. The posture adopted by the subjects consisted of the bent forearm with elbow angle of 90° and neutral wrist position, as described in the ISO 10819 standard. The pressure distribution at the hand-handle interface was also measured to quantify the static contact force corresponding to each combination of grip force, push force and handle size. The hand-handle coupling force, as defined in ISO/WD 15230, was further evaluated by summing the grip and push forces. The measured total absorbed power revealed relatively low inter-subject variability (generally less than 12%). Total absorbed power was found to be better correlated with coupling force than the contact force, while most of the absorbed power occurred in the low-frequency range, below 200 Hz. The magnitude of power absorbed within the hand and arm was observed to be strongly dependent upon the handle size; larger handles cause higher absorption of energy. The results also suggested that the power absorption is influenced by the grip as well as push force. The results attained from ANOVA confirmed the significance of all studied factors, i.e. vibration magnitude, handle diameter, and the grip and push forces on the power absorbed into the human hand and arm exposed to vibration.

Aldien, Y.; Marcotte, P.; Rakheja, S.; Boileau, P.-É.

2006-03-01

225

Design, fabrication and characterization of a very low frequency piezoelectric energy harvester designed for heart beat vibration scavenging  

NASA Astrophysics Data System (ADS)

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 60?W and 10?W 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.

Colin, M.; Basrour, S.; Rufer, L.

2013-05-01

226

A fail-safe magnetorheological energy absorber for shock and vibration isolation  

NASA Astrophysics Data System (ADS)

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.

Bai, Xian-Xu; Wereley, Norman M.

2014-05-01

227

A fail-safe magnetorheological energy absorber for shock and vibration isolation  

SciTech Connect

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.

Bai, Xian-Xu, E-mail: bai@hfut.edu.cn [Department of Vehicle Engineering, Hefei University of Technology, Hefei 230009 (China); Wereley, Norman M. [Department of Aerospace Engineering, University of Maryland, College Park, Maryland 20742 (United States)

2014-05-07

228

Investigation of geometries of bistable piezoelectric-laminate plates for vibration-based energy harvesting  

NASA Astrophysics Data System (ADS)

The need for reduced power requirements for small electronic components, such as wireless sensor networks, has prompted interest in recent years for energy harvesting technologies capable of capturing energy from broadband ambient vibrations. Encouraging results have been reported for an arrangement of piezoelectric layers attached to carbon fiber / epoxy laminates which possess bistability by virtue of their specific asymmetric stacking sequence. The inherent bistability of the underlying structure is exploited for energy harvesting since a transition from one stable configuration to another, or `snap-through', is used to repeatedly strain the surface-bonded piezoelectric and generate electrical energy. Existing studies, both experimental and modelling, have been limited to simple geometric laminate shapes, restricting the scope for improved energy harvesting performance by limiting the number of design variables. In this paper we present an analytical model to predict the static shapes of laminates of any desired profile, validated experimentally using a digital image correlation system. Good accuracy in terms of out-of-plane displacements (5-7%) are shown in line with existing square modelling results. The static model is then mapped to a dynamics model and used to compare results against an experimental study of the harvesting performance of an example arbitrary geometry piezoelectric-laminate energy harvester.

Betts, David N.; Bowen, Christopher R.; Inman, Daniel J.; Weaver, Paul M.; Kim, H. A.

2014-04-01

229

Improved design of linear electromagnetic transducers for large-scale vibration energy harvesting  

NASA Astrophysics Data System (ADS)

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.

Tang, Xiudong; Zuo, Lei; Lin, Teng; Zhang, Peisheng

2011-03-01

230

Solar energy power generation system  

SciTech Connect

A solar energy power generation system is described which consists of: (a) means for collecting and concentrating solar energy; (b) heat storage means; (c) Stirling engine means for producing power; (d) first heat transfer means for receiving the concentrated solar energy and for transferring heat to the heat storage means; and (e) second heat transfer means for controllably transferring heat from the storage means to the Stirling engine means and including a discharge heat pipe means for transferring heat to the Stirling engine means and further including means for inserting and withdrawing the discharge heat pipe means into and out of the heat storage means.

Nilsson, J.E.; Cochran, C.D.

1986-05-06

231

Invited talk, IEEE Int. Symp. Micro-NanoMechatoronics and Human Science (MHS2008), Nagoya, (2008), pp. 180-183. Energy Harvesting from Vibration Using Polymer Electret  

E-print Network

applications of electrets such as acoustic/mechanical transducers and air filter have been proposed [14 for large output power. Figure 2 shows power spectra of vibration acceleration in a car cabin. Since high Figure 1. Vibration-driven power generator. Figure 2. Power spectra of vibration in a car cabin. -180

Kasagi, Nobuhide

232

Random vibration analysis of the Topaz-II nuclear reactor power system. Master`s thesis  

SciTech Connect

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.

Campbell, S.E.

1995-06-01

233

Energy harvesting for self-powered aerostructure actuation  

NASA Astrophysics Data System (ADS)

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.

Bryant, Matthew; Pizzonia, Matthew; Mehallow, Michael; Garcia, Ephrahim

2014-04-01

234

Vibrational energy on surfaces: Ultrafast flash-thermal conductance of molecular monolayers  

NASA Astrophysics Data System (ADS)

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.

Dlott, Dana

2008-03-01

235

Mechanism of vibrational energy dissipation of free OH groups at the air-water interface.  

PubMed

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

Hsieh, Cho-Shuen; Campen, R Kramer; Okuno, Masanari; Backus, Ellen H G; Nagata, Yuki; Bonn, Mischa

2013-11-19

236

Active Seismic Monitoring Using High-Power Moveable 40-TONS Vibration Sources in Altay-Sayn Region of Russia  

NASA Astrophysics Data System (ADS)

The paper presents data of operating vibroseismic observations using high-power stationary 100-tons and moveable 40-tons vibration sources, which have been carried out in Russia for 30 years. It is shown that investigations using high-power vibration sources open new possibilities for study stressedly-deformed condition of the Earth`s crust and the upper mantle and tectonic process in them. Special attention is given to developing operating seismic translucences of the Earth`s crust and the upper mantle using high-power 40-tons vibration sources. As a result of experimental researches there was proved high stability and repeatability of vibration effects. There were carried out long period experiments of many days with vibration source sessions of every two hours with the purpose of monitoring accuracy estimation. It was determined, that repeatability of vibroseismic effects (there was researched time difference of repeated sessions of P- and S-waves from crystal rocks surface) could be estimated as 10-3 - 10-4 sec. It is ten times less than revealed here annual variations of kinematic parameters according to regime vibroseismic observations. It is shown, that on hard high-speed grounds radiation spectrum becomes narrowband and is dislocated to high frequency; at the same time quantity of multiple high-frequency harmonic is growing. At radiation on soft sedimentary grounds (sand, clay) spectrum of vibration source in near zone is more broadband, correlograms are more compact. there Correspondence of wave fields from 40-tons vibration sources and explosions by reference waves from boundaries in he Earth`s crust and the upper mantle at record distance of 400 km was proved by many experiments in various regions of Russia; there was carried out the technique of high-power vibration sources grouping for increase of effectiveness of emanation and increase of record distance. According to results of long-term vibroseismic monitoring near Novosibirsk (1997-2012) there are determined variations in velocities of longitudinal and transverse waves. Both from 100-tons and 40-tons vibration sources there are distinctly determined annual and semiannual variations, and also variations of 120 and 90 days. There is determined correlations of revealed variations of P- and S-wave velocities with drowning of the upper part of the Earth`s crust because of season changes of water volumes in the biggest Novosibirsk water reservoir. There were carried out experiments on aperture widening of operating vibroseismic observations in seismic active zones of the South of Altay. All these results prove possibility of using moveable collapsible 40-tons vibration sources for active monitoring of seismic dangerous zones, nuclear power plants, nuclear waste storage etc.

Soloviev, V. M.; Seleznev, V. S.; Emanov, A. F.; Kashun, V. N.; Elagin, S. A.; Romanenko, I.; Shenmayer, A. E.; Serezhnikov, N.

2013-05-01

237

High frequency vibration energy transfer in a system of three plates connected at discrete points using statistical energy analysis  

NASA Astrophysics Data System (ADS)

Vibration energy transfer in a system of three plates separated by a small distance and connected at a few discrete points, like solar panels in a spacecraft, is investigated. Coupling loss factors are obtained experimentally using the power injection technique. The system is then subjected to the acoustic excitation in a reverberant chamber. The measured responses of the inner plate are significant. But the measured responses of the inner plates are higher than the responses estimated based on the coupling loss factors obtained. When the system is subjected to mechanical excitation the measured responses of the inner plate closely match with the estimated responses. The difference is perhaps due to the sound radiated from the outer plates not being considered for the calculation, requiring further studies.

Renji, K.; Mahalakshmi, M.

2006-09-01

238

Stresa, Italy, 26-28 April 2006 VIBRATIONAL ENERGY SCAVENGING WITH SI TECHNOLOGY  

E-print Network

Stresa, Italy, 26-28 April 2006 VIBRATIONAL ENERGY SCAVENGING WITH SI TECHNOLOGY ELECTROMAGNETIC present the design and optimization of an electromagnetic inertial microgenerator for energy scavenging. For such applications, an interesting option is the use of inertial microgenerators for energy scavenging from

Boyer, Edmond

239

FRONTIERS ARTICLE Imaging bond breaking and vibrational energy transfer in small water  

E-print Network

FRONTIERS ARTICLE Imaging bond breaking and vibrational energy transfer in small water containing it is possible to generate accurate potential energy surfaces (PESs) for small clusters, such as those of water (REMPI) are used to determine accurate bond dissociation energies (D0) of (H2O)2, (H2O)3, HCl­H2O and NH3

Reisler, Hanna

240

An elastic-support model for enhanced bistable piezoelectric energy harvesting from random vibrations  

NASA Astrophysics Data System (ADS)

To overcome the defect of conventional nonlinear piezoelectric cantilever vibration energy harvesters, in this paper we conceive an elastic-support model to study the performance of energy converters under two types of variable-intensity excitation conditions: filtered Gaussian noises and pink noises. When excitation intensity is insufficient, thanks to the system's variable potential function, frequent bistable transition oscillations between two wells occur in elastic-support systems, while only weak oscillations in either well could be observed in rigid-support systems. In practical applications, the structural parameters of energy harvesters are not allowed to make real-time changes. If considered remaining the magnet interval and the spring's elastic stiffness unchanged while receiving stable maximum output voltage, elastic-support systems can be made full use toward variable-intensity filtered Gaussian noises. It has been proven that elastic-support systems are capable of adapting to random excitations with variable intensity, through which maximum power output and sufficient electromechanical energy conversion of the system can be accomplished.

Leng, Y. G.; Gao, Y. J.; Tan, D.; Fan, S. B.; Lai, Z. H.

2015-02-01

241

Vibrational and total energy dependence of the reaction rate of Na with CO2 laser-excited SF6  

Microsoft Academic Search

The rate of reaction between sodium and sulfur hexafluoride has been studied as a function of the vibrational energy and total thermal energy of the SF6 in the temperature range 380–440 °K. Vibrational energy was increased by absorption of radiation from a pulsed CO2 laser, and total energy was increased by heating the reaction system. The reaction rate was determined

Mark Eyal; Frederick R. Grabiner; Uri Agam; Leonard A. Gamss

1981-01-01

242

Improved energy harvesting from wideband vibrations by nonlinear piezoelectric converters  

Microsoft Academic Search

Vibration harvesters typically are linear mass-spring devices working at resonance. A different approach is here proposed based on nonlinear converters that exploit stochastic resonance with white-noise excitation. It consists of a piezoelectric beam converter coupled to permanent magnets to create a bistable system. Under proper conditions, the system bounces between two stable states in response to random excitation, which significantly

M. Ferrari; V. Ferrari; M. Guizzetti; B. Andò; S. Baglio; C. Trigona

2010-01-01

243

Accurate potential energy, dipole moment curves, and lifetimes of vibrational states of heteronuclear alkali dimers  

SciTech Connect

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}?{sup +} electronic state using the coupled cluster with singles doubles and triples method. All-electron quadruple-? basis sets with additional core functions are used for Li and Na, and small-core relativistic effective core potentials with quadruple-? 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.; Varganov, Sergey A., E-mail: svarganov@unr.edu [Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0216 (United States); Derevianko, Andrei [Department of Physics, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0220 (United States)] [Department of Physics, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0220 (United States)

2014-05-14

244

Sound power radiation from a vibrating structure in terms of structure-dependent radiation modes  

NASA Astrophysics Data System (ADS)

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 of the s-modes dominating, each s-mode tends to be largely affected either by the same ordered structural mode for a non-resonant frequency or by the resonant mode for a resonant frequency. As a result, the coupling relations between the dominating radiation modes and the associated structural modes can be revealed explicitly. In general, s-modes are recommended to be used to describe the sound power radiation from a vibrating structure whose geometry sizes are much larger than the acoustic wavelength, should its structural modes and the associated modal amplitudes have been somehow obtained.

Ji, Lin; Bolton, J. Stuart

2015-01-01

245

Energy Industry Powers CTE Program  

ERIC Educational Resources Information Center

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…

Khokhar, Amy

2012-01-01

246

High resolution studies of dissociative electron attachment to molecules: dependence on electron and vibrational energy  

NASA Astrophysics Data System (ADS)

For several molecules which are important for plasma processing and gaseous dielectrics (CF3I, CF3Br, CH3Br, and SF6), we have studied the dependence of dissociative electron attachment (DEA) on both the electron energy and on the initial vibrational energy. With reference to electron swarm data, we determine highly-resolved absolute DEA cross sections over a broad energy range, using the Laser Photoelectron Attachment (LPA) method (E = 0-0.2 eV, ?E ? 1-3 meV) and the EXtended Laser Photoelectron Attachment (EXLPA) method (0-2 eV, ?E ? 15-30 meV). The experimental data are compared with the results of R-matrix calculations, involving ab initioinformation on the potential energy curves and semiempirical autodetachment widths. For CF3I and CF3Br, previous DEA cross sections are found to be substantially too high. For CH3Br, the measurements confirm a predicted vibrational Feshbach resonance, associated with the v3 = 4 vibrational threshold, and the value of the activation energy (due to an intermediate barrier) for this exothermic DEA process. For SF6, we report absolute cross sections for SF6- as well as SF5- formation for vibrational temperatures ranging from 200 to 500 K. Moreover, the first absoluteDEA cross sections (SF5- formation) for CO2-laser excited SF6 molecules have been obtained at different initial vibrational temperatures. The results indicate that the effect of the mode-selective energy input into the v3-mode (predominantly v3 = 1) on the enhancement of SF5- formation is very similar to that of a corresponding rise of the average vibrational energy by thermal heating; at E = 2 meV electron energy, the results indicate an activation energy of about 0.38 eV.

Ruf, M.-W.; Braun, M.; Marienfeld, S.; Fabrikant, I. I.; Hotop, H.

2007-11-01

247

The thermal effects on high-frequency vibration of beams using energy flow analysis  

NASA Astrophysics Data System (ADS)

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.

Zhang, Wenbo; Chen, Hualing; Zhu, Danhui; Kong, Xiangjie

2014-04-01

248

Vibrational Energy Harvester based on Electrical Double Layer of Ionic Liquid  

NASA Astrophysics Data System (ADS)

To boost the output of the vibration energy harvester an order of magnitude higher, we devised a high-performance energy harvester taking advantages of the two characteristics of ionic liquid, namely variable deformation of liquid and the electrical double layer between ionic liquid and metal. The electrical double layer is approximately 1nm thick and works as insulator within the voltage range of ±2.0V. Therefore, we can obtain quite high capacitance(1- 10?/cm2). Squeezing and drawing ionic liquid between a pair of vibrating electrodes, we can obtain a ?W-class energy harvester.

Yamada, S.; Mitsuya, H.; Fujita, H.

2014-11-01

249

Analysis of vibrational-translational energy transfer using the direct simulation Monte Carlo method  

NASA Technical Reports Server (NTRS)

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.

Boyd, Iain D.

1991-01-01

250

Energy Finite Element Analysis Developments for Vibration Analysis of Composite Aircraft Structures  

NASA Technical Reports Server (NTRS)

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.

Vlahopoulos, Nickolas; Schiller, Noah H.

2011-01-01

251

Time averaging the semiclassical initial value representation for the calculation of vibrational energy levels. II.  

E-print Network

energy levels. II. Application to H2CO, NH3 , CH4, CH2D2 Alexey L. Kaledin and William H. Miller densities of molecules, previously tested successfully on H2O, is applied here to several larger molecules dynamics, however, the phase space average converges more slowly. Results for vibrational energy levels

Miller, William H.

252

Low power interface IC's for electrostatic energy harvesting applications  

NASA Astrophysics Data System (ADS)

The application of wireless distributed micro-sensor systems ranges from equipment diagnostic and control to real time structural and biomedical monitoring. A major obstacle in developing autonomous micro-sensor networks is the need for local electric power supply, since using a battery is often not a viable solution. This void has sparked significant interest in micro-scale power generators based on electrostatic, piezoelectric and electromagnetic energy conversion that can scavenge ambient energy from the environment. In comparison to existing energy harvesting techniques, electrostatic-based power generation is attractive as it can be integrated using mainstream silicon technologies while providing higher power densities through miniaturization. However the power output of reported electrostatic micro-generators to date does not meet the communication and computation requirements of wireless sensor nodes. The objective of this thesis is to investigate novel CMOS-based energy harvesting circuit (EHC) architectures to increase the level of harvested mechanical energy in electrostatic converters. The electronic circuits that facilitate mechanical to electrical energy conversion employing variable capacitors can either have synchronous or asynchronous architectures. The later does not require synchronization of electrical events with mechanical motion, which eliminates difficulties in gate clocking and the power consumption associated with complex control circuitry. However, the implementation of the EHC with the converter can be detrimental to system performance when done without concurrent optimization of both elements, an aspect mainly overlooked in the literature. System level analysis is performed to show that there is an optimum value for either the storage capacitor or cycle number for maximum scavenging of ambient energy. The analysis also shows that maximum power is extracted when the system approaches synchronous operation. However, there is a region of interest where the storage capacitor can be optimized to produce almost 70% of the ideal power taken as the power harvested with synchronous converters when neglecting the power consumption associated with synchronizing control circuitry. Theoretical predictions are confirmed by measurements on an asynchronous EHC implemented with a macro-scale electrostatic converter prototype. Based on the preceding analysis, the design of a novel ultra low power electrostatic integrated energy harvesting circuit is proposed for efficient harvesting of mechanical energy. The fundamental challenges of designing reliable low power sensing circuits for charge constrained electrostatic energy harvesters with capacity to self power its controller and driver stages are addressed. Experimental results are presented for a controller design implemented in AMI 0.7muM high voltage CMOS process using a macro-scale electrostatic converter prototype. The EHC produces 1.126muW for a power investment of 417nW with combined conduction and controller losses of 450nW which is a 20-30% improvement compared to prior art on electrostatic EHCs operating under charge constrain. Inherently dual plate variable capacitors harvest energy only during half of the mechanical cycle with the other half unutilized for energy conversion. To harvest mechanical energy over the complete mechanical vibration cycle, a low power energy harvesting circuit (EHC) that performs charge constrained synchronous energy conversion on a tri-plate variable capacitor for maximizing energy conversion is proposed. The tri-plate macro electrostatic generator with capacitor variation of 405pF to 1.15nF and 405pF to 1.07nF on two complementary adjacent capacitors is fabricated and used in the characterization of the designed EHC. The integrated circuit fabricated in AMI 0.7muM high voltage CMOS process, produces a total output power of 497nW to a 10muF reservoir capacitor from a 98Hz vibration signal. In summary, the thesis lays out the theoretical and experimental foundation for overcoming the main challenges associated with the desi

Kempitiya, Asantha

253

The vibrational energies of ozone up to the dissociation threshold: Dynamics calculations on an accurate potential energy surface  

E-print Network

The vibrational energies of ozone up to the dissociation threshold: Dynamics calculations present an ab initio potential energy surface for the ground electronic state of ozone. It is global, i. All bound states of nonrotating ozone up to more than 99% of the dissociation energy are calculated

Farantos, Stavros C.

254

Design of high-efficiency vibration energy harvesters and experimental functional tests for improving bandwidth and tunability  

NASA Astrophysics Data System (ADS)

The reduction of power consumption of sensors allows the local power supply or wireless sensor networks. This paper introduces the results of design and experiments on devices for harvesting energy from vibrations of machines. The main contribution of this research is the empirical evaluation of different technical solutions able to improve harvester performances and sensing system duty cycle. Satisfactory results have been achieved in lowering of resonance by levitating suspensions and in increasing of Q-factor by studying the air flows. Output power values of 10mW (5.7Hz, 1.4g) and 115mW (3.2Hz, 0.2g) were obtained for piezoelectric and inductive harvesters respectively.

Somà, A.; De Pasquale, G.

2013-05-01

255

Energy harvesting from coherent resonance of horizontal vibration of beam excited by vertical base motion  

SciTech Connect

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.

Lan, C. B.; Qin, W. Y. [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072 (China)

2014-09-15

256

Effect of collision energy and vibrational excitation on endothermic ion-molecule reactions  

SciTech Connect

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.

Turner, T.P.

1984-07-01

257

A bi-annular-gap magnetorheological energy absorber for shock and vibration mitigation  

NASA Astrophysics Data System (ADS)

For semi-active shock and vibration mitigation systems using magnetorheological energy absorbers (MREAs), the minimization of the field-off damper force of the MREA at high speed is of particular significance because the damper force due to the viscous damping at high speed becomes too excessive and thus the controllable dynamic force range that is defined by the ratio of the field-on damper force to the field-off damper force is significantly reduced. In this paper, a bi-annular-gap MREA with an inner-set permanent magnet is proposed to decrease the field-off damper force at high speed while keeping appropriate dynamic force range for improving shock and vibration mitigation performance. In the bi-annular-gap MREA, two concentric annular gaps are configured in parallel so as to decrease the baseline damper force and both magnetic activation methods using the electromagnetic coil winding and the permanent magnet are used to keep holding appropriate magnetic intensity in these two concentric annular gaps in the consideration of failure of the electric power supply. An initial field-on damper force is produced by the magnetic field bias generated from the inner-set permanent magnet. The initial damper force of the MREA can be increased (or decreased) through applying positive (or negative) current to the electromagnetic coil winding inside the bi-annular-gap MREA. After establishing the analytical damper force model of the bi-annular-gap MREA using a Bingham-plastic nonlinear fluid model, the principle and magnetic properties of the MREA are analytically validated and analyzed via electromagnetic finite element analysis (FEA). The performance of the bi-annular-gap MREA is also theoretically compared with that of a traditional single-annular- gap MREA with the constraints of an identical volume by the performance matrix, such as the damper force, dynamic force range, and Bingham number with respect to different excitation velocities.

Bai, Xian-Xu; Wereley, Norman M.; Choi, Young-Tai; Wang, Dai-Hua

2012-04-01

258

Vibration transmission through periodic structures using a mobility power flow approach  

NASA Technical Reports Server (NTRS)

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.

Cuschieri, J. M.

1990-01-01

259

Vibrational energy flow models for the Rayleigh-Love and Rayleigh-Bishop rods  

NASA Astrophysics Data System (ADS)

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.

Han, Ju-Bum; Hong, Suk-Yoon; Song, Jee-Hun; Kwon, Hyun-Wung

2014-01-01

260

ENergy and Power Evaluation Program  

SciTech Connect

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.

NONE

1996-11-01

261

Comparison of Five Topologies of Cantilever-based MEMS Piezoelectric Vibration Energy Harvesters  

NASA Astrophysics Data System (ADS)

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 ? AlN on 10 ?m Si) with the same practical dimensions of 500 ?m and 2000 ?m, suggest a cantilever with a coupled subsidiary cantilever yield the best power performance, closely followed by the classical plain topology.

Jia, Y.; Seshia, A. A.

2014-11-01

262

A wind energy powered wireless temperature sensor node.  

PubMed

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 k? 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

Zhang, Chuang; He, Xue-Feng; Li, Si-Yu; Cheng, Yao-Qing; Rao, Yang

2015-01-01

263

Net energy analysis: Powerful tool for selecting electric power options  

NASA Astrophysics Data System (ADS)

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.

Baron, S.

264

The effects of vibrational mode and collision energy on the reaction of formaldehyde cation with carbonyl sulfide  

E-print Network

The effects of vibrational mode and collision energy on the reaction of formaldehyde cation of Utah, Salt Lake City, Utah 84112 Received 7 August 2002; accepted 23 August 2002 The effects of collision energy (Ecol) and five different H2CO vibrational modes on the title reaction have been studied

Anderson, Scott L.

265

A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion  

SciTech Connect

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.

Sun, Kyung Ho; Kim, Young-Cheol [Department of System Dynamics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jae Eun, E-mail: jekim@cu.ac.kr [School of Mechanical and Automotive Engineering, Catholic University of Daegu, 13-13 Hayang-Ro, Hayang-Eup, Gyeongsan-Si, Gyeongsangbuk-Do 712-702 (Korea, Republic of)

2014-10-15

266

Tidal energy in electric power systems  

Microsoft Academic Search

This paper discusses the uses and advantages of tidal energy in restructured power systems. The paper defines the resources as well as the ways in which tidal energy is converted into electricity. The paper also reviews a few tidal power projects around the world. It also shows the working of hydro tidal power plant. A comparative review of renewable energy

S. Sheth; M. Shahidehpour

2005-01-01

267

Stresa, Italy, 25-27 April 2007 CHARACTERISATION OF AN ELECTROSTATIC VIBRATION HARVESTER  

E-print Network

Stresa, Italy, 25-27 April 2007 CHARACTERISATION OF AN ELECTROSTATIC VIBRATION HARVESTER T. Sterken ambient vibration is proposed as an alternative to storage based power supplies for autonomous systems. The system presented converts the mechanical energy of a vibration into electrical energy by means

Paris-Sud XI, Université de

268

Study of vibrational energy localization and redistribution in hydrogen peroxide H2O2 at low energy  

E-print Network

Study of vibrational energy localization and redistribution in hydrogen peroxide H2O2 at low energy in hydrogen peroxide H2O2 is studied at about 4000 cm-1 above the quantum mechanical ground state using the ab contributes to this effort by presenting a study of IVR in hydrogen peroxide H2O2 at about 4000 cm-1 above

269

7/30/2014 Smart sensors that harvest power from sun, heat or vibrations https://ec.europa.eu/programmes/horizon2020/en/print/688 1/2  

E-print Network

7/30/2014 Smart sensors that harvest power from sun, heat or vibrations https://ec.europa.eu/programmes/horizon2020) Smart sensors that harvest power from sun, heat or vibrations Published by newsroom editor that allows wireless sensor networks to power themselves from the sun, heat or vibrations. The innovation

Rossi, Michele

270

A new global approach using a network of piezoelectric elements and energy redistribution for enhanced vibration damping of smart structure  

NASA Astrophysics Data System (ADS)

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.

Wu, Dan; Guyomar, Daniel; Richard, Claude

2013-04-01

271

The influence of collision and vibrational energy on the reaction with acetylene  

E-print Network

The influence of collision and vibrational energy on the reaction of CH3CHO¿ with acetylene Ho-Tae Kim, Jianbo Liu, and Scott L. Anderson Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850 Received 22 January 2001; accepted 21 February 2001 Reaction of acetaldehyde cations

Anderson, Scott L.

272

Effects of reagent translational and vibrational energy on the dynamics of endothermic reactions  

SciTech Connect

The endothermic reactions Br + CH/sub 3/I ..-->.. CH/sub 3/ + IBr (..delta..H/sub 0//sup 0/ = 13 kcal/mole) and Br + CF/sub 3/I ..-->.. CF/sub 3/ + IBr (..delta..H/sub 0//sup 0/ = 11 kcal/mole) have been studied by the crossed molecular beams method. Detailed center-of-mass contour maps of the IBr product flux as a function of recoil velocity and scattering angle are derived. For both systems it is found that the IBr product is sharply backward scattered with respect to the incident Br dirction, and that most of the available energy goes into product translation. Vibrational enhancement of the Br + CF/sub 3/I reaction was investigated by using the infrared multiphoton absorption process to prepare highly vibrationally excited CF/sub 3/I. At a collision energy of 31 kcal/mole (several times the barrier height), reagent vibrational energy appears to be less effective than an equivalent amount of (additional) translational energy in promoting reaction. More forward scattered IBr is produced in reactions of Br with vibrationally hot CF/sub 3/I.

Krajnovich, D.; Zhang, Z.; Huisken, F.; Shen, Y.R.; Lee, Y.T.

1981-07-01

273

Oscillator strengths, HuangRhys parameters, and vibrational quantum energies of cerium-doped gadolinium oxyorthosilicate  

E-print Network

Oscillator strengths, Huang­Rhys parameters, and vibrational quantum energies of cerium absorption of cerium-doped gadolinium oxyorthosilicate (Gd2SiO5:Ce) has been measured and analyzed oscillator strengths, f, are calculated from Smakula's Z. Phys. 59, 603 1930 formula and knowledge of cerium

274

Studies on vibrational excitation differential cross-sections of low-energy electron scattering from N2 molecule  

NASA Astrophysics Data System (ADS)

The vibrational excitation differential cross-sections (DCS) of low-energy electron-N2 scattering are studied using vibrational close-coupling (VCC) method and vibrational scattering potentials which include static, exchange and polarization contributions. By including the contributions of 18 partial waves, 20 vibrational states, and 16 molecular symmetries (up to ?=7), the converged vibrational excitation (0?2, 0?3, 0?4) DCS agree well with experimental results. Also obtained are converged vibrational (1?0, 1?1, 1?2, 1?3) DCS, with the impact energies being those of the main resonant peaks (1.92 eV, 1.90 eV, 1.62 eV, 1.63 eV).

Dai, W.; Sun, W. G.; Feng, H.; Shen, L.

2006-09-01

275

A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.  

PubMed

A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 ??, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. PMID:21507747

Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

2011-04-01

276

Transformation of potential energy surfaces for estimating isotopic shifts in anharmonic vibrational frequency calculations  

SciTech Connect

A transformation of potential energy surfaces (PES) being represented by multi-mode expansions is introduced, which allows for the calculation of anharmonic vibrational spectra of any isotopologue from a single PES. This simplifies the analysis of infrared spectra due to significant CPU-time savings. An investigation of remaining deviations due to truncations and the so-called multi-level approximation is provided. The importance of vibrational-rotational couplings for small molecules is discussed in detail. In addition, an analysis is proposed, which provides information about the quality of the transformation prior to its execution. Benchmark calculations are provided for a set of small molecules.

Meier, Patrick; Oschetzki, Dominik; Rauhut, Guntram, E-mail: rauhut@theochem.uni-stuttgart.de [Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)] [Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Berger, Robert [Clemens-Schöpf Institut für Organische Chemie and Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt (Germany)] [Clemens-Schöpf Institut für Organische Chemie and Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt (Germany)

2014-05-14

277

Vibrational excitation of hydrogen fluoride by low-energy electrons: theory and experiment  

NASA Astrophysics Data System (ADS)

Vibrational excitation (VE) of HF by low-energy electrons has been investigated experimentally and theoretically. A new nonlocal resonance model has been constructed based on ab initio calculations of the coupling between a discrete state and continuum states. VE and resonant elastic cross sections have been calculated for a set of initial vibrational states of the molecular target. New high-resolution measurements of VE cross sections for the transitions v = 0 rightarrow 1,..., 4 have been carried out. The calculated cross sections are in good agreement with the experimental data, indicating that the mechanisms responsible for the rich threshold structures found in the collision cross sections of HF are well understood.

Cízek, M.; Horácek, J.; Allan, M.; Fabrikant, I. I.; Domcke, W.

2003-07-01

278

On the ro–vibrational energies for the lithium dimer; maximum-possible rotational levels  

NASA Astrophysics Data System (ADS)

The Deng–Fan potential is used to discuss the reliability of the improved Greene–Aldrich approximation and the factorization recipe of Badawi et al [17] for the central attractive/repulsive core J?ft( J+1 \\right)/2? {{r}2}. The factorization recipe is shown to be a more reliable approximation and is used to obtain the rotational–vibrational energies for the {{a}3}? u+–7Li2 dimer. For each vibrational state only a limited number of the rotational levels are found to be supported by the {{a}3}? u+–7Li2 dimer.

Mustafa, Omar

2015-03-01

279

The power output and efficiency of a negative capacitance shunt for vibration control of a flexural system  

NASA Astrophysics Data System (ADS)

A negative capacitance shunt is a basic, analog, active circuit electrically connected to a piezoelectric transducer to control the vibrations of flexural bodies. The shunt circuit consists of a resistor and a synthetic negative capacitor to introduce a real and imaginary impedance on a vibrating mechanical system. The electrical impedance of the negative capacitance shunt modifies the effective modulus of the piezoelectric transducer to reduce the stiffness and increase the damping, which causes a decrease in amplitude of the vibrating structure to which the elements are bonded. To gain an insight into the electromechanical coupling and power output, the shunt and the electrical properties of the piezoelectric transducer are modeled using circuit modeling software. The power output of the model is validated with experimental measurements of a shunt connected to a piezoelectric transducer pair bonded to a vibrating aluminum cantilever beam. The model is used to select the passive components of the negative capacitance shunt to increase the efficiency and quantify the voltage output limit of the op-amp.

Beck, Benjamin S.; Cunefare, Kenneth A.; Collet, Manuel

2013-06-01

280

Apparatus for generating seismic vibration energy in a borehole  

SciTech Connect

A signal generating apparatus is described for use in fluid-filled boreholes, comprising: a frame for suspension in the borehole; a tube having first and second ends and disposed in the frame a first acoustic energy source mounted in the first end to direct energy to a central point; a second acoustic energy source mounted in the second end to direct energy to the central point; an energy deflector plate disposed at 45 degrees to and along the axis of the tube central point at an equal angle to each means for energizing the first and second acoustic energy sources.

Benzing, W.M.

1986-12-30

281

Careers in Geothermal Energy: Power from below  

ERIC Educational Resources Information Center

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,…

Liming, Drew

2013-01-01

282

Vibrational Energies for Acrylonitrile from Mm-Wave to Thz Rotational Spectra  

NASA Astrophysics Data System (ADS)

The THz rotational spectrum of acrylonitrile has recently been studied in detail. The coverage of the ground state rotational transitions has been extended up to J=128, K_a=29 and it was found that at very high-J there are multiple manifestations of a perturbation between the ground state and the lowest vibrationally excited state, V11=1. The perturbation has been successfully fitted and the excited state energy determined at 228.29991(2) Cm-1, which turns out to be the largest energy difference between any two neighboring vibrational states of acrylonitrile. Extensive broadband rotational spectra of acrylonitrile have been recorded at JPL and at OSU and provide coverage from the mm-wave region up to well into the THz. The analysis of these spectra performed with the AABS package allowed identification of a ladder of pairwise perturbations extending from the ground state and connecting all successive low lying vibrational states. A global fit of all of the observed effects is expected to deliver accurate energies for the lowest vibrational states from only the rotational spectrum. The progress made towards achieving this goal is described. Z.Kisiel, L.Pszczó?kowski, B.J.Drouin, C.S.Brauer, S.Yu, J.C.Pearson, J. Mol. Spectrosc., 258, 26 (2009). Z.Kisiel, L.Pszczó?kowski, I.R.Medvedev, M.Winewisser, F.C.De Lucia, E.Herbst, J. Mol. Spectrosc., 233, 231 (2005).

Kisiel, Zbigniew; Pszczó?kowski, Lech; Drouin, Brian J.; Brauer, Carolyn S.; Yu, Shanshan; Pearson, John C.; Medvedev, Ivan R.; Fortman, Sarah; Neese, Christopher

2011-06-01

283

Vibration Condition Monitoring Techniques for Fault Diagnosis of Electromotor with 1.5 Kw Power  

NASA Astrophysics Data System (ADS)

Vibration analysis is the main conditions monitoring techniques for machinery maintenance and fault diagnosis. This technique has its unique advantages and disadvantages associated with the monitoring and fault diagnosis of machinery. When this technique is conducted independently, only a portion of machine faults are typically diagnosed. However, practical experience has shown that this technique in a machine condition monitoring program provides useful reliable information, bringing significant cost benefits to industry. The objective of this research is to investigate the correlation between vibration analysis and fault diagnosis. This was achieved by vibration analysis and investigating different operating conditions of an experimental electromotor. The electromotor was initially run under normal operating conditions as a comparative test. A series of tests were then conducted corresponding to different operating condition. Our varieties were speed of electromotor at three levels, respectively 500, 1000 and 1500 rpm. We did three faults in our electromotor; there were misalignment, looseness and bad bearing. We coupled our electromotor to the variable blade fan and applied several load on that by changing the number of blade of fan. We have chosen 2, 6 and 10 blades fan to apply three different loads on our electromotor. Vibration data was regularly collected. Numerical data produced by vibration analysis were compared with vibration spectra in normal condition of healthy machine, in order to quantify the effectiveness of the vibration condition monitoring technique. The results from this paper have given more understanding on the dependent roles of vibration analysis in predicting and diagnosing machine faults.

Mohamadi Monavar, H.; Ahmadi, H.; Mohtasebi, S. S.; Hasani, S.

284

Estimating the vibration level of an L-shaped beam using power flow techniques  

NASA Technical Reports Server (NTRS)

The response of one component of an L-shaped beam, with point force excitation on the other component, is estimated using the power flow method. The transmitted power from the source component to the receiver component is expressed in terms of the transfer and input mobilities at the excitation point and the joint. The response is estimated both in narrow frequency bands, using the exact geometry of the beams, and as a frequency averaged response using infinite beam models. The results using this power flow technique are compared to the results obtained using finite element analysis (FEA) of the L-shaped beam for the low frequency response and to results obtained using statistical energy analysis (SEA) for the high frequencies. The agreement between the FEA results and the power flow method results at low frequencies is very good. SEA results are in terms of frequency averaged levels and these are in perfect agreement with the results obtained using the infinite beam models in the power flow method. The narrow frequency band results from the power flow method also converge to the SEA results at high frequencies. The advantage of the power flow method is that detail of the response can be retained while reducing computation time, which will allow the narrow frequency band analysis of the response to be extended to higher frequencies.

Cuschieri, J. M.; Mccollum, M.; Rassineux, J. L.; Gilbert, T.

1986-01-01

285

Alternative Energy and Remote Power Products  

NSDL National Science Digital Library

Based in Alaska, ABS Alaskan provides batteries, alternative energy and remote and power products. The site contains a Library link, where users can explore a basic power system diagram, visit the document download center, and find information explaining alternative energy and power systems.

286

Vibrations of micro-eV energies in nanocrystalline microstructures.  

PubMed

The phonon density of states of nanocrystalline bcc Fe and nanocrystalline fcc Ni3Fe were measured by inelastic neutron scattering in two different ranges of energy. As has been reported previously, the nanocrystalline materials showed enhancements in their phonon density of states at energies from 2 to 15 meV, compared to control samples composed of large crystals. The present measurements were extended to energies in the micro-eV range, and showed significant, but smaller, enhancements in the number of modes in the energy range from 5 to 18 microeV. These modes of micro-eV energies provide a long-wavelength limit that bounds the fraction of modes at milli-eV energies originating with the cooperative dynamics of the nanocrystalline microstructure. PMID:15600935

Yue, A F; Papandrew, A B; Delaire, O; Fultz, B; Chowdhuri, Z; Dimeo, R M; Neumann, D A

2004-11-12

287

Flow-induced vibration  

SciTech Connect

This book reports on dimensional analysis; ideal fluid models; vortex-induced vibration; galloping and flutter; instability of tube and cylinder arrays; vibrations induced by oscillating flow; vibration induced by turbulence and sound; damping of structures; sound induced by vortex shedding; vibrations of a pipe containing a fluid flow; indices. It covers the analysis of the vibrations of structures exposed to fluid flows; explores applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.

Blevins, R.D.

1990-01-01

288

Piezoelectrochemical effect: Mechanical energy induced redox reaction in aqueous solutions through vibrating piezoelectric materials  

NASA Astrophysics Data System (ADS)

We propose a phenomenon of piezoelectrochemical (PZEC) effect for the direct conversion of mechanical energy to chemical energy. This phenomenon is further applied for generating hydrogen and oxygen via direct water decomposition by means of as-synthesized piezoelectric quartz (SiO2) nano-rods, ZnO microfibers, and BaTiO3 microdendrites. The materials are vibrated with ultrasonic waves leading to a strain-induced electric charge development on their surface. With sufficient electric potential, the strained piezoelectric materials in water triggered the redox reaction of water to produce hydrogen and oxygen gases. All materials have indicated a well response to the external mechanical vibration to drive the desired chemical reactions. ZnO fibers under ultrasonic vibrations showed a stoichiometric ratio of H 2/O2 (2:1) initial gas production from pure water. The efficiency of the piezoelectrochemical effect was calculated by ratio of the chemical energy output over the mechanical energy input of the system. The study of piezoelectrochemical effect is further applied to the environmental cleaning technology. Accordingly, a dissolved orange dye (AO7) was decomposed via mechanical driving force by using BaTiO3 microdendrites. Kinetic details of the dye decomposition through piezoelectrochemical effect were investigated. In addition, the piezoelectrochemical effect was proposed to the implication of tectonic hydrogen in geological systems providing insights of hydrogen generation in active fault zones. The tectonic hydrogen produced through PZEC effect could be a sustainable energy source for subsurface microbial community. This study provides a simple and cost-effective technology for generating hydrogen fuels as well as environmental cleaning by scavenging energy wastes such as noise or stray vibrations from the environment. This new piezoelectrochemical effect may have potential implications in solving the challenging energy and environmental issues that we are facing today and in the future.

Hong, Kuang-Sheng

289

Effect of whole body vibrations on performance indexes of aerobic power and flexibility in non-athlete men  

Microsoft Academic Search

The aim of the present study was to investigate the effect of one session whole body vibration (WBV) on anaerobic power and flexibility in non-athletic male students. The participants were 12 untrained healthy male students (age: 25.42 years; body mass: 72.99 kg; height: 175.92 cm and body fat percentage: 19.69%). On the day of assessment, the subjects carried out 10

Babak Davoodi; Sajad Arshadi; Shirin Zilaei Bouri

2010-01-01

290

Energy storage systems for advanced power applications  

Microsoft Academic Search

While energy storage technologies do not represent energy sources, they provide valuable added benefits to improve stability power quality, and reliability of supply. Battery technologies have improved significantly in order to meet the challenges of practical electric vehicles and utility applications. Flywheel technologies are now used in advanced nonpolluting uninterruptible power supplies. Advanced capacitors are being considered as energy storage

PAULO F. RIBEIRO; BRIAN K. JOHNSON; MARIESA L. CROW; AYSEN ARSOY; YILU LIU

2001-01-01

291

Electromagnetic energy harvesting from vibrations of multiple frequencies  

Microsoft Academic Search

A novel multi-frequency energy harvester has been designed and fabricated, which consists of three permanent magnets, three sets of two-layer copper coils and a supported beam of acrylic, while these coils are made of thin fire resistant 4 (FR4) substrates using a standard printed circuit board. The energy under the first, second and third resonant modes can be harvested, corresponding

Bin Yang; Chengkuo Lee; Wenfeng Xiang; Jin Xie; Johnny Han He; Rama Krishna Kotlanka; Siew Ping Low; Hanhua Feng

2009-01-01

292

Mode-Specific Vibrational Energy Relaxation of Amide I and II Modes in N-Methylacetamide/Water Clusters: Intra-and Intermolecular Energy Transfer  

E-print Network

Mode-Specific Vibrational Energy Relaxation of Amide I and II Modes in N, 2008; ReVised Manuscript ReceiVed: February 2, 2009 The mode-specific vibrational energy relaxation of the amide I and amide II modes in NMA-d1/(D2O)n (n ) 0-3) clusters were studied using the time

Straub, John E.

293

Bonneville Power Administration's Purchasing of Energy Savings  

E-print Network

BONNEVILLE POWER ADMINISTRATION'S PURCHASE OF ENERGY SAVINGS Harold (Skip) Schick Leslie E. McMillan Bonneville Power Administration Port1and, Oregon INTRODUCTION The Bonneville Power Administration (BPA) is conducting a commercial... of several activities BPA is conductin9 to develop the capabil ity to conserve energy in the com mercial sector of electrical energy use. This paper describes the benefits of the approach, the program des ign, 1essons 1earned through field testing...

Schick, H.

294

The reduction of rotorcraft power and vibration using optimally controlled active gurney flap  

NASA Astrophysics Data System (ADS)

The main topic of the present study is the application of active control scheme for the reduction of rotorcraft main rotor power reduction and vibratory load. When the helicopter is operated near its flight boundary, the required power and vibratory loads rapidly increases which impose a limit on the helicopter operation. Various methods were proposed and studied in order to achieve performance improvement under such operating condition. The effect of active control scheme was examined for its impact on the performance improvement and vibration reduction in the present study. Numerical simulations are based on the UH-60A Blackhawk helicopter with an active Gurney flap spanning from 70%R to 80%R of the main rotor. For obtaining the aeroelastic response of the rotor blade, finite element method was used to represent elastic blade. The aerodynamic loads acting on the blade are provided by CFD based 2D lookup table. Prescribed wake model was used to resolve the induced inflow over the rotor disk. The unsteady aerodynamic behavior due to the higher harmonic actuation of active Gurney flap was resolved by the time-domain unsteady aerodynamic model. The first part of preliminary study covers parametric study using Gurney flap. Starting with simple rigid blade representation of the rotor blade, the effect of 1/rev Gurney flap actuation was examined on three different gross weights. The effect of active Gurney flap width, the chordwise location of active Gurney flap, the effect of unsteady aerodynamic model, and the effect of 2/rev actuation frequency were examined. The second part of preliminary study was conducted with the elastic blade model to include the effect of torsion dynamics. Performance improvement using active Gurney flap was examined for maximizing thrust capability at two flight speeds. 1/rev Gurney flap actuation increased the gross weight capability up to 1,000 lbs. Also, 1/rev actuation of Gurney flap increased maximum altitude limit of baseline rotor by 1,400 ft. Furthermore, it was predicted that the maximum level flight speed can be increased by 30 knots with respect to that of the baseline rotor. The effect of active Gurney flap on the vibration reduction was first examined at the stall condition. Using 1/rev actuation, in-plane vibratory force and moment can be reduced by 68% and 44%, respectively. The effects of higher harmonic frequencies were investigated at the high-speed cruise speed, and single frequency phase sweep was conducted to find the best phase angle that minimizes each vibratory components. 3/rev actuation yielded 36% reduction in in-plane vibratory moment. 74% reduction in vertical vibratory force was predicted with 4/rev actuation. With 5/rev actuation, 81% reduction in vertical vibratory load was observed. With the input-output information obtained from single frequency phase sweep, the plant model which correlates active control inputs to helicopter vibratory loads was constructed. Multicyclic controller was applied to the plant model, and 25% reduction in the cost function was reported. Vertical vibratory load was reduced by 51%, and inplane force and moment were reduced by 18%, 22%, respectively.

Bae, Eui Sung

295

Low-frequency vibration energy harvesting using a locally resonant phononic crystal plate with spiral beams  

NASA Astrophysics Data System (ADS)

A low-frequency vibration energy generator has been proposed by using a locally resonant phononic crystal plate which has spiral beams connecting the scatterers and the matrix. Finite element analysis shows that at the flat bands frequencies of the phononic crystal, locally resonant leads to the spiral beams having strong deformations which are perpendicular to the plate. A designed structure with three PC cells arranged in the same direction was adopted for the experiments. Piezoelectric patches were adhered on the end of the spiral beams and then the collected vibration energy could be converted into electric energy. The maximum single-channel output voltage which reached as much as 13 V was obtained at the first flat band frequency 29.2 Hz in the experiment. Meanwhile, in the low-frequency range of 0-500 Hz, it showed that the piezoelectric transformation could be conducted at a dozen of resonant frequencies. Furthermore, through modulating the structure parameters, this phononic crystal has the potential to realize broad-distributed vibration energy harvesting.

Shen, Li; Wu, Jiu Hui; Zhang, Siwen; Liu, Zhangyi; Li, Jing

2015-01-01

296

Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

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.

Offenhaeuser, F.

1987-01-01

297

Performance enhancement of a rotational energy harvester utilizing wind-induced vibration of an inclined stay cable  

NASA Astrophysics Data System (ADS)

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.

Kim, In-Ho; Jang, Seon-Jun; Jung, Hyung-Jo

2013-07-01

298

Free vibrations of an uncertain energy pumping system  

NASA Astrophysics Data System (ADS)

The aim of this paper is to study the energy pumping (the irreversible energy transfer from one structure, linear, to another structure, nonlinear) robustness considering the uncertainties of the parameters of a two DOF mass-spring-damper, composed of two subsystems, coupled by a linear spring: one linear subsystem, the primary structure, and one nonlinear subsystem, the so-called NES (nonlinear energy sink). Three parameters of the system will be considered as uncertain: the nonlinear stiffness and the two dampers. Random variables are associated to the uncertain parameters and probability density functions are constructed for the random variables applying the Maximum Entropy Principle. A sensitivity analysis is then performed, considering different levels of dispersion, and conclusions are obtained about the influence of the uncertain parameters in the robustness of the system.

Cataldo, Edson; Bellizzi, Sergio; Sampaio, Rubens

2013-12-01

299

Distribution of vibrational potential energy in molecular systems  

NASA Astrophysics Data System (ADS)

It is shown that for a collection of n classical harmonic oscillators, the long-time distribution of potential energies P is approximated by sinm(?P) for n?4, where m=(8n/?2-1/?2) and P is scaled to lie between 0 and 1. As n??, the distribution tends to a ?-function centered about P=0.5. When coupling is present between the oscillators, the effective value of m is reduced, so that the breadth of the potential energy distribution reflects the degree of randomization in the system.

Pritchard, Huw O.; Raj Vatsya, S.; Shen, DeLin

1999-05-01

300

Vibrational and Translational Energy Effects in the Reaction of Ammonia Ions with Water Michael A. Everest, John C. Poutsma, and Richard N. Zare*  

E-print Network

Vibrational and Translational Energy Effects in the Reaction of Ammonia Ions with Water Molecules of vibrationally state-selected ammonia ions with deuterated water is investigated with a quadrupole energies from 0.5 to 10.0 eV (center of mass) and ammonia ion vibrational states 1020-10 and 1122

Zare, Richard N.

301

Non-classicality of the molecular vibrations assisting exciton energy transfer at room temperature  

PubMed Central

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

O’Reilly, Edward J.; Olaya-Castro, Alexandra

2014-01-01

302

Layout optimization methodology of piezoelectric transducers in energy-recycling semi-active vibration control systems  

NASA Astrophysics Data System (ADS)

An optimization methodology is proposed for the piezoelectric transducer (PZT) layout of an energy-recycling semi-active vibration control (ERSAVC) system for a space structure composed of trusses. Based on numerical optimization techniques, we intend to generate optimal location of PZTs under the constraint for the total length of PZTs. The design variables are set as the length of the PZT on each truss based on the concept of the ground structure approach. The transient problems of the mechanical and electrical vibrations based on the ERSAVC theory are considered as the equations of state. The objective is to minimize the integration of the square of all displacement over the whole analysis time domain. The sensitivity of the objective function is derived based on the adjoint variable method. Based on these formulations, an optimization algorithm is constructed using the fourth-order Runge-Kutta method and the method of moving asymptotes. Numerical examples are provided to illustrate the validity and utility of the proposed methodology. Using the proposed methodology, the optimal location of PZTs for the vibration suppression for multi-modal vibration is studied, which can be benchmark results of further study in the context of ERSAVC systems.

Takezawa, Akihiro; Makihara, Kanjuro; Kogiso, Nozomu; Kitamura, Mitsuru

2014-01-01

303

Energy analysis of wave and tidal power  

NASA Astrophysics Data System (ADS)

Energy requirements for building wave- and tidal-power systems are estimated and the relationship between energy requirements and extraction efficiency is examined for wavepower systems. It is found that a point of maximum net output is reached, beyond which further increases in extraction efficiency result in decreased net energy. In this manner, the energy analysis identifies a limit on the energy which could, in principle, be extracted by a wave-energy system. Finally, it is noted that although similar limits could be identified for other types of energy sources, the tidal power analysis is confined to a brief comparison of energy inputs and outputs.

Harrison, R.; Smith, K. G.; Varley, J. S.

1980-06-01

304

Imaging bond breaking and vibrational energy transfer in small water containing clusters  

NASA Astrophysics Data System (ADS)

This letter presents a brief overview of our recent experimental studies of state-to-state vibrational predissociation (VP) dynamics of small hydrogen bonded (H-bonded) clusters following vibrational excitation. Velocity map imaging (VMI) and resonance-enhanced multiphoton ionization (REMPI) are used to determine accurate bond dissociation energies (D0) of (H2O)2, (H2O)3, HCl-H2O and NH3-H2O. Pair-correlated product energy distributions from the VP of these complexes are also presented and compared to theoretical models. Further insights into mechanisms are obtained from the recent quasi-classical trajectory (QCT) calculations of Bowman and coworkers. The D0 values for (H2O)2 and (H2O)3 are in very good agreement with recent calculated values, and the results are used to estimate the contributions of cooperative interactions to the H-bonding network.

Samanta, Amit K.; Ch'ng, Lee C.; Reisler, Hanna

2013-06-01

305

Nonlinear small-amplitude waves in a dissipative gas with an excess of vibrational energy  

NASA Astrophysics Data System (ADS)

Results of earlier studies, concerned with the effect of energy exchange between the translational and vibrational degrees of freedom in a molecular gas on the propagation of acoustic and shock waves, are extended to the case of cylindrical and spherical waves for one-dimensional plane waves of small amplitude. An equation for gas velocity is obtained which allows for the effect of dissipative processes. Some exact solutions for this equation are presented.

Krasnobaev, K. V.; Tarev, V. Iu.

1990-04-01

306

Relative spins and excitation energies of superdeformed bands in 190Hg: Further evidence for octupole vibration  

E-print Network

An experiment using the Eurogam Phase II gamma-ray spectrometer confirms the existence of an excited superdeformed (SD) band in 190Hg and its very unusual decay into the lowest SD band over 3-4 transitions. The energies and dipole character of the transitions linking the two SD bands have been firmly established. Comparisons with RPA calculations indicate that the excited SD band can be interpreted as an octupole-vibrational structure.

B. Crowell; M. P. Carpenter; R. V. F. Janssens; D. J. Blumenthal; Timar; A. N. Wilson; J. F. Sharpey-Schafer; T. Nakatsukasa; I. Ahmad; A. Astier; F. Azaiez; L. du Croux; B. J. P. Gall; F. Hannachi; T. L. Khoo; A. Korichi; T. Lauritsen; A. Lopez-Martens; M. Meyer; D. Nisius; E. S. Paul; M. G. Porquet; N. Redon

1994-12-29

307

Relative spins and excitation energies of superdeformed bands in $^{190}$Hg further evidence for octupole vibration  

E-print Network

An experiment using the Eurogam Phase II gamma-ray spectrometer confirms the existence of an excited superdeformed (SD) band in 190Hg and its very unusual decay into the lowest SD band over 3-4 transitions. The energies and dipole character of the transitions linking the two SD bands have been firmly established. Comparisons with RPA calculations indicate that the excited SD band can be interpreted as an octupole-vibrational structure.

Crowell, B; Janssens, R V F; Blumenthal, D J; Wilson, A N; Sharpey-Schafer, J F; Nakatsukasa, T; Ahmad, I; Astier, A; Azaiez, F; Du Croix, L; Gall, B J P; Hannachi, F; Khoo, T L; Korichi, A; Lauritsen, T; López-Martens, A; Meyer, M R; Nisius, D; Paul, E S; Porquet, M G; Redon, N; Crowell, B; Carpenter, M P; Janssens, R V F; Blumenthal, D J; Wilson, A N; Sharpey-Schafer, J F; Nakatsukasa, T; du Croux, L; Gall, B J P; Hannachi, F; Khoo, T L; Korichi, A; Lauritsen, T; Lopez-Martens, A; Meyer, M; Nisius, D; Paul, E S; Porquet, M G; Redon, N

1994-01-01

308

Communication: Fast transport and relaxation of vibrational energy in polymer chains  

NASA Astrophysics Data System (ADS)

We investigate ballistic vibrational energy transport through optical phonon band in oligomeric chains in the presence of decoherence. An exact solution is obtained for the excitation density in the space-time representation in the continuous limit and this solution is used to characterize the energy transport time and intensity. Three transport mechanisms are identified such as ballistic, diffusive, and directed diffusive regimes, occurring at different distances and time scales. The crossover between the two diffusive regimes is continuous, while the switch between the ballistic and diffusive mechanisms occurs in a discontinuous manner in accord with the recent experimental results on energy transport in perfluoroalkanes.

Kurnosov, Arkady A.; Rubtsov, Igor V.; Burin, Alexander L.

2015-01-01

309

Renewable Energy Powered Water Treatment Systems   

E-print Network

There are many motivations for choosing renewable energy technologies to provide the necessary energy to power water treatment systems for reuse and desalination. These range from the lack of an existing electricity grid, ...

Richards, Bryce S.; Schäfer, Andrea

2009-01-01

310

Energy function analysis for power system stability  

Microsoft Academic Search

Energy Function Analysis for Power System Stability presents the concept of energy function, which has found wide-spread applications for power systems in recent years. The most recent advances in five distinct areas are reviewed: Development of energy functions for structure preserving models, which can incorporate non-linear load models; energy functions which include a detailed model of the generating unit (i.e.

M. A. Pai

1989-01-01

311

Compilers for Power andCompilers for Power and Energy ManagementEnergy Management  

E-print Network

Compilers for Power andCompilers for Power and Energy ManagementEnergy Management Ulrich (UlrichISLPED'02 August 13, 2002 6 3RZHU3RZHU YVYV (QHUJ\\ (QHUJ\\ SRZHU DFWLYLW\\ OHYHO DW D JLYHQ SRLQW LQ WLPH HQHUJ\\ WRWDO DPRXQW RI DFWLYLW\\ time power time power VDPH HQHUJ\\ GLIIHUHQW SHDN#12; SRZHU RSWLPL

Kremer, Ulrich

312

Thermal energy storage for power plant applications  

Microsoft Academic Search

This study was conducted by Pacific Northwest Laboratory (PNL) to evaluate alternative methods of using coal to generate peak and intermediate load power. The approach was to review the technical and economic feasibility of using thermal energy storage (TES) with a conventional coal-fired power plant and an integrated gasification combined cycle (IGCC) power plant. In the first case, conventional pulverized

S. Somasundaram; M. K. Drost; Z. I. Antoniak; D. R. Brown

1990-01-01

313

Coordinated Management: Power, Performance, Energy, and Temperature  

E-print Network

with shorter time constants, such as current spikes in the power distribution network, and longer intervalsCoordinated Management: Power, Performance, Energy, and Temperature Heather Hanson Stephen W at Austin IBM Technical Contact : Rob Bell, Jr. Abstract We are developing a next-generation power manager

Keckler, Stephen W.

314

Picosecond IR-UV pump-probe spectroscopic study on the intramolecular vibrational energy redistribution of NH2 and CH stretching vibrations of jet-cooled aniline.  

PubMed

Intramolecular vibrational energy redistribution (IVR) of the NH2 symmetric and asymmetric stretching vibrations of jet-cooled aniline has been investigated by picosecond time-resolved IR-UV pump-probe spectroscopy. A picosecond IR laser pulse excited the NH2 symmetric or asymmetric stretching vibration of aniline in the electronic ground state and the subsequent time evolutions of the excited level as well as redistributed levels were observed by a picosecond UV pulse. The IVR lifetimes for symmetric and asymmetric stretches were obtained to be 18 and 34 ps, respectively. In addition, we obtained the direct evidence that IVR proceeds via two-step bath states; that is, the NH2 stretch energy first flows into the doorway state and the energy is further dissipated into dense bath states. The rate constants of the second step were estimated to be comparable to or slower than those of the first step IVR. The relaxation behavior was compared with that of IVR of the OH stretching vibration of phenol [Y. Yamada, T. Ebata, M. Kayano, and M. Mikami J. Chem. Phys. 120, 7400 (2004)]. We found that the second step IVR process of aniline is much slower than that of phenol, suggesting a large difference of the "doorway state increasing the dense bath states" anharmonic coupling strength between the two molecules. We also observed IVR of the CH stretching vibrations, which showed much faster IVR behavior than that of the NH2 stretches. The fast relaxation is described by the interference effect, which is caused by the coherent excitation of the quasistationary states. PMID:16392491

Yamada, Yuji; Okano, Jun-ichi; Mikami, Naohiko; Ebata, Takayuki

2005-09-22

315

Power electronics and alternative energy generation  

Microsoft Academic Search

Growth in alterative energy generation technologies and markets will have a major impact on the development of power electronics in the future. The paper discusses some of these implications, and outlines the technological and performance challenges for power electronic systems in alternative energy applications.

James P Lyons; Vlatko Vlatkovic

2004-01-01

316

ENERGY, POWER AND ENVIRONMENT (Environmental Analytical Chemistry)  

E-print Network

the development of society has been intertwined with quest for sources of energy and power. In the middleENERGY, POWER AND ENVIRONMENT (Environmental Analytical Chemistry) CHEM 6284/CHEM 4803 Fall 2014 3 of radiation with matter; measurement of radiation; nuclear reactions; 9/30 10/2-9 Midterm Health effects

Sherrill, David

317

Solar energy thermally powered electrical generating system  

NASA Technical Reports Server (NTRS)

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.

Owens, William R. (Inventor)

1989-01-01

318

Second Proof Work, Power, and Energy  

E-print Network

) energy sources, such as solar energy, wind, water flows, ocean and tidal waves, and biomassSecond Proof Work, Power, and Energy M. KOSTIC Northern Illinois University DeKalb, Illinois, United States 1. Basic Concepts 2. Forms, Classifications, and Conservation of Energy 3. Work

Kostic, Milivoje M.

319

Nuclear Power Trends Energy Economics and Sustainability  

E-print Network

Nuclear Power Trends Energy Economics and Sustainability L. H. Tsoukalas Purdue University Nuclear;National Research Council of Greece, May 8, 2008 Outline · The Problem · Nuclear Energy Trends · Energy Economics · Life Cycle Analysis · Nuclear Sustainability · Nuclear Energy in Greece? #12;National Research

320

Anharmonic force field, vibrational energies, and barrier to inversion of SiH{sub 3}{sup -}  

SciTech Connect

The full quartic force field of the ground electronic state of the silyl anion (SiH{sub 3}{sup -}) has been determined at the CCSD(T)-R12 level employing a [Si/H]=[16s11p6d5f/7s5p4d] basis set. The vibrational energy levels, using the quartic force field as a representation of the potential energy hypersurface around equilibrium, have been determined by vibrational perturbation theory carried out to second, fourth, and sixth order. The undetected vibrational fundamental for the umbrella mode, {nu}{sub 2}, is predicted to be 844 cm-1. High-quality ab initio quantum chemical methods, including higher-order coupled cluster (CC) and many-body perturbation (MP) theory with basis sets ranging from [Si/H] [5s4p2d/3s2p] to [8s7p6d5f4g3h/7s6p5d4f3g] have been employed to obtain the best possible value for the inversion barrier of the silyl anion. The rarely quantified effects of one- and two-particle relativistic terms, core correlation, and the diagonal Born-Oppenheimer correction (DBOC) have been included in the determination of the barrier for this model system. The final electronic (vibrationless) extrapolated barrier height of this study is 8351{+-}100 cm{sup -1}. (c) 2000 American Institute of Physics.

Aarset, Kirsten [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary)] [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary); Csaszar, Attila G. [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary)] [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary); Sibert, Edwin L. III [Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)] [Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Allen, Wesley D. [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)] [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Schaefer, Henry F. III [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)] [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Klopper, Wim [Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, (Norway) [Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, (Norway); Theoretical Chemistry Group, Debye Institute, Utrecht University, Padualaan 14, NL-3584 CH Utrecht, The Netherlands (Netherlands); Noga, Jozef [Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-84236 Bratislava, (Slovakia)] [Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-84236 Bratislava, (Slovakia)

2000-03-01

321

Testing Skyrme energy-density functionals with the QRPA in low-lying vibrational states of rare-earth nuclei  

E-print Network

Although nuclear energy density functionals are determined primarily by fitting to ground state properties, they are often applied in nuclear astrophysics to excited states, usually through the quasiparticle random phase approximation (QRPA). Here we test the Skyrme functionals SkM* and SLy4 along with the self-consistent QRPA by calculating properties of low-lying vibrational states in a large number of well-deformed even-even rare-earth nuclei. We reproduce trends in energies and transition probabilities associated with gamma-vibrational states, but our results are not perfect and indicate the presences of multi-particle-hole correlations that are not included in the QRPA. The Skyrme functional SkM* performs noticeably better than SLy4. In a few nuclei, changes in the treatment of the pairing energy functional have a significant effect. The QRPA is less successful with "beta-vibrational" states than with the gamma-vibrational states.

J. Terasaki; J. Engel

2011-05-19

322

Testing Skyrme energy-density functionals with the QRPA in low-lying vibrational states of rare-earth nuclei  

E-print Network

Although nuclear energy density functionals are determined primarily by fitting to ground state properties, they are often applied in nuclear astrophysics to excited states, usually through the quasiparticle random phase approximation (QRPA). Here we test the Skyrme functionals SkM* and SLy4 along with the self-consistent QRPA by calculating properties of low-lying vibrational states in a large number of well-deformed even-even rare-earth nuclei. We reproduce trends in energies and transition probabilities associated with gamma-vibrational states, but our results are not perfect and indicate the presences of multi-particle-hole correlations that are not included in the QRPA. The Skyrme functional SkM* performs noticeably better than SLy4. In a few nuclei, changes in the treatment of the pairing energy functional have a significant effect. The QRPA is less successful with "beta-vibrational" states than with the gamma-vibrational states.

Terasaki, J

2011-01-01

323

Dissociative attachment and vibrational excitation in low-energy electron collisions with chlorine molecules  

NASA Astrophysics Data System (ADS)

In a combined experimental and theoretical effort, we have investigated dissociative attachment and vibrational excitation in low-energy electron collisions with chlorine molecules. Using the laser photoelectron attachment method, we have measured the energy dependence of the cross section sgrDA(E) for dissociative electron attachment (Cl- formation) over the range 0-195 meV with an energy width of 1-3 meV and for Rydberg electron transfer at high principal quantum numbers (n>67). Near zero energy, the cross section shows a behaviour compatible with the threshold law for p-wave attachment via the 2Sgru+ resonance, reaches a maximum around 50 meV and declines towards higher energies. These findings are in good agreement with the results of semi-empirical R-matrix calculations. Measured rate coefficients knl for Cl- formation due to electron transfer from K**(nl) Rydberg atoms were found to be nearly constant for high principal quantum numbers (n>67) in contrast to the behaviour expected within the quasi-free electron model for p-wave attachment. The R-matrix calculations are extended to describe electron attachment through the 2Pgrg and 2Pgru resonances, and recommended absolute cross sections for dissociative attachment to chlorine molecules at room temperature are provided over the energy range 0-9 eV. Furthermore, we predict cross sections for vibrationally inelastic electron scattering through the 2Sgru+, 2Pgrg and 2Pgru resonances.

Ruf, M.-W.; Barsotti, S.; Braun, M.; Hotop, H.; Fabrikant, I. I.

2004-01-01

324

Attachment and vibrational excitation in low-energy electron collisions with chlorine molecules  

NASA Astrophysics Data System (ADS)

In a combined experimental and theoretical effort, we have investigated attachment and vibrational excitation in low-energy electron collisions with chlorine molecules. Using the laser photoelectron attachment method, we have measured the energy dependence of the cross section for dissociative electron attachment (Cl^- formation) over the range 0 - 195 meV with an energy width of 1-3 meV. Near zero energy, the cross section shows a behavior compatible with the threshold law for p-wawe attachment via the ^2?_u^+ resonance, reaches a maximum around 50 meV and declines towards higher energies. These findings are in very good agreement with the results of semiempirical R-matrix calculations. The latter are extended to describe attachment through the ^2?g and ^2?u resonances, and recommended absolute cross sections for dissociative attachment to chlorine molecules at room temperature are provided over the energy range 0 - 9 eV. Furthermore, we predict cross sections for vibrationally inelastic scattering through the ^2?_u^+, ^2?_g, and ^2?u resonances.

Fabrikant, Ilya; Barsotti, Stefano; Ruf, Martin; Hotop, Hartmut

2003-05-01

325

Time Resolved Infrared Emission from Vibrational Excited Acetylene Following Super Energy Transfer Collisions with Hot Hydrogen  

NASA Astrophysics Data System (ADS)

Can a molecule be activated with large amounts of energy transferred in a single collision between an atom and a molecule? If so, this type of collision will greatly affect molecular reactivity and equilibrium in systems including combustion where abundant hot atoms exist. Conventional expectation of translation to vibration (T-V) energy transfer is that probability decreases exponentially with energy transferred. We show, however, that in collisions between a pair of atom/molecule for which chemical reactions may occur, such as between a hyperthermal H atom and an ambient acetylene molecule, (T-V) energy transfer occurs with surprisingly high efficiency through chemical complex formation. Time-resolved infrared emission observations reveal that collisions between H atoms moving with 60 kcal/mole energy and acetylene molecules result in transfer of up to 70% of this energy into vibrational degrees of freedom. These experimental results are further supported by state of the art quasi-classical trajectory calculations performed by Bowman and coworkers.

Smith, J. M.; Nikow, M.; Dai, J. Ma Andh. L.

2013-06-01

326

Shock and vibration tests of uranium mononitride fuel pellets for a space power nuclear reactor  

NASA Technical Reports Server (NTRS)

Shock and vibration tests were conducted on cylindrically shaped, depleted, uranium mononitride (UN) fuel pellets. The structural capabilities of the pellets were determined under exposure to shock and vibration loading which a nuclear reactor may encounter during launching into space. Various combinations of diametral and axial clearances between the pellets and their enclosing structures were tested. The results of these tests indicate that for present fabrication of UN pellets, a diametral clearance of 0.254 millimeter and an axial clearance of 0.025 millimeter are tolerable when subjected to launch-induced loads.

Adams, D. W.

1972-01-01

327

A comparison of filter diagonalisation methods with the Lanczos method for calculating vibrational energy levels  

NASA Astrophysics Data System (ADS)

In this Letter we compare two low-storage filter diagonalisation methods for calculating energy levels and compare both to the Lanczos algorithm. We are able to calculate energy levels in a high-lying window in the vibrational spectrum of H 2O with fewer matrix-vector products using the Lanczos algorithm than using the filter diagonalisation methods. We find that the Lanczos calculation is less costly and that the cost of building the Hamiltonian and overlap matrices in the filtered basis is excessive if one uses a non-Chebyshev discrete variable representation filter.

Huang, Shi-Wei; Carrington, Tucker

1999-10-01

328

Compact inductive energy storage pulse power system  

NASA Astrophysics Data System (ADS)

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 ?s 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.

K, Senthil; Mitra, S.; Roy, Amitava; Sharma, Archana; Chakravarthy, D. P.

2012-05-01

329

Scavenging vibration energy from seismically isolated bridges using an electromagnetic harvester  

NASA Astrophysics Data System (ADS)

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.

Lu, Qiuchen; Loong, Chengning; Chang, Chih-Chen; Dimitrakopoulos, Elias G.

2014-04-01

330

Modeling energy transport in a cantilevered Euler-Bernoulli beam actively vibrating in Newtonian fluid  

NASA Astrophysics Data System (ADS)

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.

Faria, Cassio T.; Inman, Daniel J.

2014-04-01

331

Vibrational vs. translational energy in promoting a prototype metal–hydrocarbon insertion reaction  

PubMed Central

The reaction Y + CH4 ? HYCH3 ? YCH2 + H2 is initiated by C–H insertion involving a 20 ± 3 kcal/mol potential energy barrier. The reaction is studied in crossed molecular beams under two different conditions with nearly the same total energy. One experiment is carried out at a collision energy of 15.1 kcal/mol with one quantum of CH4 antisymmetric (?3) stretching vibrational excitation (8.63 kcal/mol), the other at a collision energy of 23.8 kcal/mol. The reaction cross-section for C–H stretch excited methane (?s) is found to be at least a factor of 2.2 times larger than for ground-state methane (?g) at the same total energy. PMID:18678904

Proctor, David L.; Davis, H. Floyd

2008-01-01

332

Compensation of a digitally controlled static power converter for the damping of rolling mill torsional vibration  

Microsoft Academic Search

A significant advance in damping of torsional vibration by the application of an additional control loop is described. The control feeds measured spindle torque into the drive current regulator, typically increasing damping by 50 to 100%, which is comparable with other damping methods reviewed. A scale model and a large full-scale mill have both been tested with the new control

D. H. E. Butler; M. A. Churches; Y. Anbe; H. Naitoh

1992-01-01

333

Compensation of a digitally controlled static power converter for the damping of rolling mill torsional vibration  

Microsoft Academic Search

A significant advance in damping of torsional vibration by the application of an additional control loop is described. The control feeds measured spindle torque into the drive current regulator, typically increasing damping by 50% to 100%, comparable to other damping methods reviewed. A scale model and a large full-scale mill have been tested with the new control loop. The increased

DAVID H. E. BUTLER; MICHAEL A. CHURCHES; E. R. Vergan; Y. Anbe; H. Naitoh

1990-01-01

334

Energy Finite Element Analysis for Computing the High Frequency Vibration of the Aluminum Testbed Cylinder and Correlating the Results to Test Data  

NASA Technical Reports Server (NTRS)

The Energy Finite Element Analysis (EFEA) is a finite element based computational method for high frequency vibration and acoustic analysis. The EFEA solves with finite elements governing differential equations for energy variables. These equations are developed from wave equations. Recently, an EFEA method for computing high frequency vibration of structures either in vacuum or in contact with a dense fluid has been presented. The presence of fluid loading has been considered through added mass and radiation damping. The EFEA developments were validated by comparing EFEA results to solutions obtained by very dense conventional finite element models and solutions from classical techniques such as statistical energy analysis (SEA) and the modal decomposition method for bodies of revolution. EFEA results have also been compared favorably with test data for the vibration and the radiated noise generated by a large scale submersible vehicle. The primary variable in EFEA is defined as the time averaged over a period and space averaged over a wavelength energy density. A joint matrix computed from the power transmission coefficients is utilized for coupling the energy density variables across any discontinuities, such as change of plate thickness, plate/stiffener junctions etc. When considering the high frequency vibration of a periodically stiffened plate or cylinder, the flexural wavelength is smaller than the interval length between two periodic stiffeners, therefore the stiffener stiffness can not be smeared by computing an equivalent rigidity for the plate or cylinder. The periodic stiffeners must be regarded as coupling components between periodic units. In this paper, Periodic Structure (PS) theory is utilized for computing the coupling joint matrix and for accounting for the periodicity characteristics.

Vlahopoulos, Nickolas

2005-01-01

335

Electrostatic Force-induced Broadband Effect in Electret- based Vertical Vibration Energy Harvesters using Finegrained Stainless Steel Oscillator  

NASA Astrophysics Data System (ADS)

We propose a fine-grained stainless-steel as a promising material for a robust oscillator and investigate the dependence of frequency band width, resonance frequency, and output power on initial air gaps in electret-based vertical vibration energy harvesters. Beams of the oscillator showed a shallow side-etched depth less than 10 ?m, as well as smooth edges. The oscillator succeeded in travelling over 1-mm displacement without fracture. Also, we found that broader frequency band, as well as lower resonance frequency, can be achieved with reducing the initial air gap, whereas the output power exhibited a peak value at an optimal initial air gap. The results may be attributed to the soft spring effect induced by the stronger electrostatic force. Maximum output power density and FWHM of frequency band width of our harvester are 4.7 ?W/cm3 and 14 Hz at initial air gap 0.3 mm and acceleration 4.9 m/s2.

Asanuma, H.; Hara, M.; Oguchi, H.; Kuwano, H.

2014-11-01

336

Topology optimization and fabrication of low frequency vibration energy harvesting microdevices  

NASA Astrophysics Data System (ADS)

Topological design of miniaturized resonating structures capable of harvesting electrical energy from low frequency environmental mechanical vibrations encounters a particular physical challenge, due to the conflicting design requirements: low resonating frequency and miniaturization. In this paper structural static stiffness to resist undesired lateral deformation is included into the objective function, to prevent the structure from degenerating and forcing the solution to be manufacturable. The rational approximation of material properties interpolation scheme is introduced to deal with the problems of local vibration and instability of the low density area induced by the design dependent body forces. Both density and level set based topology optimization (TO) methods are investigated in their parameterization, sensitivity analysis, and applicability for low frequency energy harvester TO problems. Continuum based variation formulations for sensitivity analysis and the material derivative based shape sensitivity analysis are presented for the density method and the level set method, respectively; and their similarities and differences are highlighted. An external damper is introduced to simulate the energy output of the resonator due to electrical damping and the Rayleigh proportional damping is used for mechanical damping. Optimization results for different scenarios are tested to illustrate the influences of dynamic and static loads. To demonstrate manufacturability, the designs are built to scale using a 3D microfabrication method and assembled into vibration energy harvester prototypes. The fabricated devices based on the optimal results from using different TO techniques are tested and compared with the simulation results. The structures obtained by the level set based TO method require less post-processing before fabrication and the structures obtained by the density based TO method have resonating frequency as low as 100 Hz. The electrical voltage response in the experiment matches the trend of the simulation data.

Deng, Jiadong; Rorschach, Katherine; Baker, Evan; Sun, Cheng; Chen, Wei

2015-02-01

337

The Assistance of Molecular Vibrations on Coherent Energy Transfer in Photosynthesis from the View of Quantum Heat Engine  

E-print Network

Recently the quantum nature in the energy transport in solar cell and light-harvesting complexes have attracted much attention, as being triggered by the experimental observations. We model the light-harvesting complex (i.e., PEB50 dimer) as a quantum heat engine (QHE) and study the effect of the undamped intra-molecule vibrational modes on the coherent energy transfer process and quantum transport. We find that the exciton-vibration interaction has non-trivial contribution to the promotion of quantum yield as well as transport properties of the quantum heat engine at steady state, by enhancing the quantum coherence quantified by entanglement entropy. The perfect quantum yield over 90% has been obtained, with theexciton-vibration coupling. We attribute these improvements to the renormalization of the electronic couplings effectively induced by exciton-vibration interaction and the subsequent delocalization of excitons. Finally we demonstrate that the thermal relaxation and dephasing can help the excitation en...

Zhang, Zhedong

2015-01-01

338

Power Electronics in Renewable Energy Systems  

Microsoft Academic Search

The global electrical energy consumption is still rising and there is a steady demand to increase the power capacity. It is expected that it has to be doubled within 20 years. The production, distribution and use of the energy should be as technological efficient as possible and incentives to save energy at the end-user should also be set up. Deregulation

F. Blaabjerg; F. Iov; R. Teodorescu; Z. Chen

2006-01-01

339

Teachers Environmental Resource Unit: Energy and Power.  

ERIC Educational Resources Information Center

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…

Bemiss, Clair W.

340

Laser Fusion Energy The High Average Power  

E-print Network

Laser Fusion Energy and The High Average Power Program John Sethian Naval Research Laboratory Dec for Inertial Fusion Energy with lasers, direct drive targets and solid wall chambers Lasers DPPSL (LLNL) Kr posters Snead Payne #12;Laser(s) Goals 1. Develop technologies that can meet the fusion energy

341

Laser energy converted into electric power  

NASA Technical Reports Server (NTRS)

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.

Shimada, K.

1973-01-01

342

Target isotope effects for vibrationally-resolved electron capture in low-energy collisions of O3+ with molecular hydrogen  

E-print Network

Target isotope effects for vibrationally-resolved electron capture in low-energy collisions of O3+ with molecular hydrogen P. C. Stancil Department of Physics and Astronomy and the Center for Simulational Physics hydrogen isotopomers (H2, HD, T2) for collision energies of 1 and 100 eV/u. Potential energy surfaces

Stancil, Phillip C.

343

Vibrational mode and collision energy effects on reaction Jianbo Liu, Brian Van Devener, and Scott L. Andersona)  

E-print Network

Vibrational mode and collision energy effects on reaction of H2CO¿ with C2D4 Jianbo Liu, Brian Van Devener, and Scott L. Andersona) Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 different H2CO vibrational modes on the reaction of H2CO with C2D4 over the center-of-mass Ecol range from 0

Anderson, Scott L.

344

A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels  

SciTech Connect

In this paper we report a new ground state potential energy surface for ethylene (ethene) C{sub 2}H{sub 4} obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82?542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C{sub 2}H{sub 4} molecule was obtained with a RMS(Obs.–Calc.) deviation of 2.7 cm{sup ?1} for fundamental bands centers and 5.9 cm{sup ?1} for vibrational bands up to 7800 cm{sup ?1}. Large scale vibrational and rotational calculations for {sup 12}C{sub 2}H{sub 4}, {sup 13}C{sub 2}H{sub 4}, and {sup 12}C{sub 2}D{sub 4} isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm{sup ?1} are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of {sup 13}C{sub 2}H{sub 4} and {sup 12}C{sub 2}D{sub 4} and rovibrational levels of {sup 12}C{sub 2}H{sub 4}.

Delahaye, Thibault, E-mail: thibault.delahaye@univ-reims.fr; Rey, Michaël, E-mail: michael.rey@univ-reims.fr; Tyuterev, Vladimir G. [Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, BP 1039, F-51687, Reims Cedex 2 (France); Nikitin, Andrei [Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, Russian Academy of Sciences, 634055 Tomsk, Russia and Quamer, State University of Tomsk (Russian Federation); Szalay, Péter G. [Institute of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest (Hungary)

2014-09-14

345

Vibrational energy flow in the villin headpiece subdomain: Master equation simulations.  

PubMed

We examine vibrational energy flow in dehydrated and hydrated villin headpiece subdomain HP36 by master equation simulations. Transition rates used in the simulations are obtained from communication maps calculated for HP36. In addition to energy flow along the main chain, we identify pathways for energy transport in HP36 via hydrogen bonding between residues quite far in sequence space. The results of the master equation simulations compare well with all-atom non-equilibrium simulations to about 1 ps following initial excitation of the protein, and quite well at long times, though for some residues we observe deviations between the master equation and all-atom simulations at intermediate times from about 1-10 ps. Those deviations are less noticeable for hydrated than dehydrated HP36 due to energy flow into the water. PMID:25702030

Leitner, David M; Buchenberg, Sebastian; Brettel, Paul; Stock, Gerhard

2015-02-21

346

Vibrational energy flow in the villin headpiece subdomain: Master equation simulations  

NASA Astrophysics Data System (ADS)

We examine vibrational energy flow in dehydrated and hydrated villin headpiece subdomain HP36 by master equation simulations. Transition rates used in the simulations are obtained from communication maps calculated for HP36. In addition to energy flow along the main chain, we identify pathways for energy transport in HP36 via hydrogen bonding between residues quite far in sequence space. The results of the master equation simulations compare well with all-atom non-equilibrium simulations to about 1 ps following initial excitation of the protein, and quite well at long times, though for some residues we observe deviations between the master equation and all-atom simulations at intermediate times from about 1-10 ps. Those deviations are less noticeable for hydrated than dehydrated HP36 due to energy flow into the water.

Leitner, David M.; Buchenberg, Sebastian; Brettel, Paul; Stock, Gerhard

2015-02-01

347

Power Measurement Methods for Energy Efficient Applications  

PubMed Central

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

Calandrini, Guilherme; Gardel, Alfredo; Bravo, Ignacio; Revenga, Pedro; Lázaro, José L.; Toledo-Moreo, F. Javier

2013-01-01

348

Fast vibrational calculation of anharmonic OH-stretch frequencies for two low-energy noradrenaline conformers  

NASA Astrophysics Data System (ADS)

We introduce a new reduced-coupling technique to accelerate direct calculations of a selected number of vibrational frequencies in large molecular systems. Our method combines the advantages of the single-to-all correlation-corrected vibrational self-consistent field (STA-CC-VSCF) approach [D. M. Benoit, J. Chem. Phys. 125, 244110 (2006)] with those of the fast-CC-VSCF technique [D. M. Benoit, J. Chem. Phys. 120, 562 (2004)] and allows the ab initio calculation of only the relevant parts of the required potential energy surface (PES). We demonstrate, using a set of five aliphatic alcohol molecules, that the new fast-STA-CC-VSCF method is accurate and leads to very substantial time gains for the computations of the PES. We then use the fast-STA-CC-VSCF method to accelerate the computation of the OH-stretch and NH-stretch frequencies of the two lowest-energy conformers of noradrenaline, namely, AG1a and GG1a. Our new approach enables us to run the calculation 89 times faster than the standard CC-VSCF technique and makes it possible to use a high-level MP2/TZP description of the PES. We demonstrate that the influence of the strong mode-mode couplings is crucial for a realistic description of the particular OH-stretch vibrational signature of each conformer. Finally, of the two possible low-energy conformers, we identify AG1a as the one most likely to have been observed in the experiments of Snoek et al. [Mol. Phys. 101, 1239 (2003)].

Benoit, David M.

2008-12-01

349

Fast vibrational calculation of anharmonic OH-stretch frequencies for two low-energy noradrenaline conformers.  

PubMed

We introduce a new reduced-coupling technique to accelerate direct calculations of a selected number of vibrational frequencies in large molecular systems. Our method combines the advantages of the single-to-all correlation-corrected vibrational self-consistent field (STA-CC-VSCF) approach [D. M. Benoit, J. Chem. Phys. 125, 244110 (2006)] with those of the fast-CC-VSCF technique [D. M. Benoit, J. Chem. Phys. 120, 562 (2004)] and allows the ab initio calculation of only the relevant parts of the required potential energy surface (PES). We demonstrate, using a set of five aliphatic alcohol molecules, that the new fast-STA-CC-VSCF method is accurate and leads to very substantial time gains for the computations of the PES. We then use the fast-STA-CC-VSCF method to accelerate the computation of the OH-stretch and NH-stretch frequencies of the two lowest-energy conformers of noradrenaline, namely, AG1a and GG1a. Our new approach enables us to run the calculation 89 times faster than the standard CC-VSCF technique and makes it possible to use a high-level MP2/TZP description of the PES. We demonstrate that the influence of the strong mode-mode couplings is crucial for a realistic description of the particular OH-stretch vibrational signature of each conformer. Finally, of the two possible low-energy conformers, we identify AG1a as the one most likely to have been observed in the experiments of Snoek et al. [Mol. Phys. 101, 1239 (2003)]. PMID:19102529

Benoit, David M

2008-12-21

350

SPS Energy Conversion Power Management Workshop  

NASA Technical Reports Server (NTRS)

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.

1980-01-01

351

Power Technologies Energy Data Book - Fourth Edition  

SciTech Connect

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.

Aabakken, J.

2006-08-01

352

Energy Decisions: Is Solar Power the Solution?  

ERIC Educational Resources Information Center

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.…

Childress, Vincent W.

2011-01-01

353

On the self-powering of SHM techniques using seismic energy harvesting  

NASA Astrophysics Data System (ADS)

Growing demands in self-powered, wireless Structural Health Monitoring (SHM) systems has placed a particular attention on energy harvesting products. While most of works done in this domain considered directly coupled active materials, it may be preferential to use seismic (or indirect-coupled) harvesters for maintenance issues. With a seismic type harvester, a model considering constant vibration magnitude excitation is no longer valid as electrical energy extraction from mechanical vibration leads to a reduction of the vibration magnitude of the harvester because of electromechanical coupling effect. This paper extends a Single Degree of Freedom (SDOF) model with a constant force or acceleration excitation to a Two Degree of Freedom (TDOF) approach to describe the tradeoff between the damping effect on the host structure and the harvested power due to the mechanical to mechanical coupling effect. When the harvester mass to host structure mass ratio is around 10-3, the maximal power is obtained and the host structure has then a sudden displacement reduction due to the strong mechanical to mechanical coupling. Its application to self-powered SHM will be also introduced in the paper.

Wu, Yi-Chieh; Lallart, Mickaël.; Yan, Linjuan; Guyomar, Daniel; Richard, Claude

2013-04-01

354

Theoretical investigation of highly excited vibrational states in DFCO: Calculation of the out-of-plane bending states and simulation of the intramolecular vibrational energy redistribution  

NASA Astrophysics Data System (ADS)

A previously developed modified Davidson scheme [C. Iung and F. Ribeiro, J. Chem. Phys. 121, 174105 (2005)] is applied to compute and analyze highly excited (?2,?6) eigenstates in DFCO. The present paper is also devoted to the simulations of the intramolecular vibrational energy redistribution (IVR) initiated by an excitation of the out-of-plane bending vibration (n?6, n =2,4,6,…,18, and 20). The multiconfiguration time-dependent Hartree method is exploited to propagate the corresponding six-dimensional wave packets. A comprehensive comparison with experimental data as well as with previous simulations of IVR in HFCO [G. Pasin et al. J. Chem. Phys. 124, 194304 (2006)] is presented.

Pasin, Gauthier; Iung, Christophe; Gatti, Fabien; Meyer, Hans-Dieter

2007-01-01

355

A refined quartic potential energy surface and large scale vibrational calculations for S0 thiophosgene.  

PubMed

In this work we present a full 6D quartic potential energy surface (PES) for S0 thiophosgene in curvilinear symmetrized bond-angle coordinates. The PES was refined starting from an ab initio field derived from acc-pVTZ basis set with CCSD(T) corrections for electron correlation. In the present calculations we used our variational method that was recently tested on formaldehyde and some of its isotopomers, along with additional improvements. The lower experimentally known vibrational levels for 35Cl2CS were reproduced quite well in the calculations, which can be regarded as a test for the feasibility of the obtained quartic PES. PMID:25615683

Rashev, Svetoslav; Moule, David C

2015-04-01

356

Influence of vibration on mechanical power and electromyogram activity in human arm flexor muscles  

Microsoft Academic Search

The aim of this study was to evaluate the influence of vibration on the mechanical properties of arm flexors. A group of\\u000a 12 international level boxers, all members of the Italian national team, voluntarily participated in the experiment: all were\\u000a engaged in regular boxing training. At the beginning of the study they were tested whilst performing forearm flexion with\\u000a an

Carmelo Bosco; Marco Cardinale; Olga Tsarpela

1999-01-01

357

Theoretical investigation of intramolecular vibrational energy redistribution in highly excited HFCO  

NASA Astrophysics Data System (ADS)

The present paper is devoted to the simulations of the intramolecular vibrational energy redistribution (IVR) in HFCO initiated by an excitation of the out-of-plane bending vibration [n?6=2,4,6,…,18,20]. Using a full six-dimensional ab initio potential energy, the multiconfiguration time-dependent Hartree (MCTDH) method was exploited to propagate the corresponding six-dimensional wave packets. This study emphasizes the stability of highly excited states of the out-of-plane bending mode which exist even above the dissociation threshold. More strikingly, the structure of the IVR during the first step of the dynamics is very stable for initial excitations ranging from 2?6 to 20?6. This latter result is consistent with the analysis of the eigenstates obtained, up to 10?6, with the aid of the Davidson algorithm in a foregoing paper [Iung and Ribeiro, J. Chem. Phys. 121, 174105 (2005)]. The present study can be considered as complementary to this previous investigation. This paper also shows how MCTDH can be used to predict the dynamical behavior of a strongly excited system and to determine the energies of the corresponding highly excited states.

Pasin, Gauthier; Gatti, Fabien; Iung, Christophe; Meyer, Hans-Dieter

2006-05-01

358

Increasing Power and Energy in Amonix CPV Solar Power Plants  

Microsoft Academic Search

Large-scale concentration photovoltaic (CPV) power plants deliver the high energy production and low electricity cost that will allow photovoltaics to become a substantial portion of the electrical grid. High concentration minimizes the semiconductor material costs, while tracking delivers higher capacity factors and provides a better match to demand. In order to prove the net cost benefits, however, annual deployments must

Geoffrey S. Kinsey; Aditya Nayak; Mingguo Liu; Vahan Garboushian

2011-01-01

359

Variational calculations of rotational-vibrational energies of CH{sub 4} and isotopomers using an adjusted ab initio potential  

SciTech Connect

The authors report variational calculations of vibrational energies of CH{sub 4}, CH{sub 3}D, CH{sub 2}D{sub 2}, CHD{sub 3}, and CD{sub 4} using the code Multimode and the ab initio force field of Lee and co-workers [Lee, T.J.; Martin, J.M.L.; Taylor, P.R.--J.Chem.Phys. 1995, 102, 254], re-expressed using Morse variables in the stretch displacements. Comparisons are made with experimental energies for CH{sub 4} with this potential, and then small adjustments are made to the potential to improve agreement with experiment for CH{sub 4}. Calculations for the isotopomers are done using the adjusted potential and compared with experiment. Additional vibrational energies and assignments not reported experimentally are also given for CH{sub 4} and the isotopomers. Exact rotational-vibrational energies of CH{sub 4} are also reported for J = 1.

Carter, S.; Bowman, J.M.

2000-03-23

360

A quasi-classical trajectory study of the OH + SO reaction: the role of ro-vibrational energy.  

PubMed

A study of the OH + SO ? H + SO2 reaction using a quasi-classical trajectory method is presented with the aim of investigating the role of the ro-vibrational energy of the reactants in the reactivity. The calculations were carried out using a previously reported global potential energy surface for HSO2((2)A). Different initial conditions with one and both reactants ro-vibrationally excited were studied. The reactive cross sections, for each studied combination, are calculated and then fitted to a capture-like model combined with a factor accounting for the recrossing effects. The Vibrational Energy Quantum Mechanical Threshold of the Complex method was used to correct for the zero-point vibrational energy leakage of the classical calculations. State specific and averaged rate constants are reported. The reactivity is affected when ro-vibrational energy of either of the reactants is changed. The present calculations provide a theoretical support for the experimental rate constant for temperatures below 550 K, but fail to account for the significant fall in the observed rate constant upon increasing the temperature above this value. PMID:24837441

Pires, W A D; Garrido, J D; Nascimento, M A C; Ballester, M Y

2014-07-01

361

High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: the effect of donor fluorination on strong collision energy transfer.  

PubMed

Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ?41,000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1?S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ?E region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ?E region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency. PMID:25527934

Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

2014-12-21

362

High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: The effect of donor fluorination on strong collision energy transfer  

NASA Astrophysics Data System (ADS)

Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm-1) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ˜41 000 cm-1 was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1?S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ?E region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ?E region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

Kim, Kilyoung; Johnson, Alan M.; Powell, Amber L.; Mitchell, Deborah G.; Sevy, Eric T.

2014-12-01

363

Coal and nuclear power: Illinois' energy future  

SciTech Connect

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.

Not Available

1982-01-01

364

Intermediate-energy differential and integral cross sections for vibrational excitation in ?-tetrahydrofurfuryl alcohol  

SciTech Connect

Differential and integral cross section measurements, for incident electron energies in the 20–50 eV range, are reported for excitation of several composite vibrational modes in ?-tetrahydrofurfuryl alcohol (THFA). Optimisation and frequency calculations, using GAUSSIAN 09 at the B3LYP/aug-cc-pVDZ level, were also undertaken for the two most abundant conformers of THFA, with results being reported for their respective mode classifications and excitation energies. Those calculations assisted us in the experimental assignments of the composite features observed in our measured energy loss spectra. There are, to the best of our knowledge, no other experimental or theoretical data currently available in the literature against which we can compare the present results.

Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Chiari, L.; Jones, D. B.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); White, R. D. [School of Engineering and Physical Sciences, James Cook University, Townsville, 4810 Queensland (Australia); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, Kuala Lumpur (Malaysia)

2014-06-07

365

Space solar power - An energy alternative  

NASA Technical Reports Server (NTRS)

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.

Johnson, R. W.

1978-01-01

366

The influence of translational and vibrational energy on the reaction of Cl with CH{sub 3}D  

SciTech Connect

The reaction of Cl atoms with CH{sub 3}D proceeds either by abstraction of hydrogen to produce HCl + CH{sub 2}D or by abstraction of deuterium to produce DCl + CH{sub 3}. Using Cl atoms with different amounts of translational energy, produced by photolysis of Cl{sub 2} with 309, 355, or 416 nm light, reveals the influence of translational energy on the relative reaction probability for the two channels. These measurements give an estimate of the energy barrier for the reaction for comparison to theory and indicate that tunneling is the dominant reaction mechanism at low collision energies. Adding two quanta of C-H stretching vibration causes the reaction to proceed readily at all collision energies. Detecting the vibrational state of the CH{sub 2}D product shows that vibrational energy initially in the surviving C-H bond appears as vibrational excitation of the product, an example of spectator behavior in the reaction. The reaction produces both stretch and stretch-bend excited products except at the lowest collision energy. A subtle variation in the reaction probability of the lowest energy rotational states with translational energy may reflect the presence of a van der Waals well in the entrance channel.

Berke, Andrew E.; Volpa, Ethan H.; Annesley, Christopher J.; Crim, F. Fleming [Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706 (United States)

2013-06-14

367

Elastic scattering, vibrational excitation, and attachment in low-energy electron- S F6 scattering: Experiment and effective range theory  

NASA Astrophysics Data System (ADS)

Cross sections at low energies for vibrationally elastic and inelastic scattering, as well as electron attachment to SF6 , have been calculated using a multichannel effective range theory (ERT) with complex boundary conditions. The most active vibrational modes, the totally symmetric mode ?1 and the infrared active mode ?3 , have been included in the calculation. The ERT parameters were fitted to reproduce the experimental total and attachment cross sections. Differential elastic and vibrational excitation cross sections have been measured at 30° and 135° using a spectrometer with hemispherical analyzers. The calculation reproduces correctly the magnitudes and shapes of the differential elastic and ?1 , ?3 , and 2?1 excitation cross sections, in particular the sharp structures at vibrational thresholds. The s - and p -wave phase shifts obtained in the present analysis differ from those recently derived by Field [Phys. Rev. A, 69, 052716 (2004)].

Fabrikant, Ilya I.; Hotop, Hartmut; Allan, Michael

2005-02-01

368

Saving Energy Through Advanced Power Strips (Poster)  

SciTech Connect

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.

Christensen, D.

2013-10-01

369

Determination of molecular vibrational state energies using the ab initio semiclassical initial value representation: Application to formaldehyde  

NASA Astrophysics Data System (ADS)

We have demonstrated the use of ab initio molecular dynamics (AIMD) trajectories to compute the vibrational energy levels of molecular systems in the context of the semiclassical initial value representation (SC-IVR). A relatively low level of electronic structure theory (HF/3-21G) was used in this proof-of-principle study. Formaldehyde was used as a test case for the determination of accurate excited vibrational states. The AIMD-SC-IVR vibrational energies have been compared to those from curvilinear and rectilinear vibrational self-consistent field/vibrational configuration interaction with perturbation selected interactions-second-order perturbation theory (VSCF/VCIPSI-PT2) and correlation-corrected vibrational self-consistent field (cc-VSCF) methods. The survival amplitudes were obtained from selecting different reference wavefunctions using only a single set of molecular dynamics trajectories. We conclude that our approach is a further step in making the SC-IVR method a practical tool for first-principles quantum dynamics simulations.

Wong, Stephanie Y. Y.; Benoit, David M.; Lewerenz, Marius; Brown, Alex; Roy, Pierre-Nicholas

2011-03-01

370

Determination of molecular vibrational state energies using the ab initio semiclassical initial value representation: application to formaldehyde.  

PubMed

We have demonstrated the use of ab initio molecular dynamics (AIMD) trajectories to compute the vibrational energy levels of molecular systems in the context of the semiclassical initial value representation (SC-IVR). A relatively low level of electronic structure theory (HF/3-21G) was used in this proof-of-principle study. Formaldehyde was used as a test case for the determination of accurate excited vibrational states. The AIMD-SC-IVR vibrational energies have been compared to those from curvilinear and rectilinear vibrational self-consistent field/vibrational configuration interaction with perturbation selected interactions-second-order perturbation theory (VSCF/VCIPSI-PT2) and correlation-corrected vibrational self-consistent field (cc-VSCF) methods. The survival amplitudes were obtained from selecting different reference wavefunctions using only a single set of molecular dynamics trajectories. We conclude that our approach is a further step in making the SC-IVR method a practical tool for first-principles quantum dynamics simulations. PMID:21384953

Wong, Stephanie Y Y; Benoit, David M; Lewerenz, Marius; Brown, Alex; Roy, Pierre-Nicholas

2011-03-01

371

Optimal Power Allocation for Renewable Energy Source  

E-print Network

Battery powered transmitters face energy constraint, replenishing their energy by a renewable energy source (like solar or wind power) can lead to longer lifetime. We consider here the problem of finding the optimal power allocation under random channel conditions for a wireless transmitter, such that rate of information transfer is maximized. Here a rechargeable battery, which is periodically charged by renewable source, is used to power the transmitter. All of above is formulated as a Markov Decision Process. Structural properties like the monotonicity of the optimal value and policy derived in this paper will be of vital importance in understanding the kind of algorithms and approximations needed in real-life scenarios. The effect of curse of dimensionality which is prevalent in Dynamic programming problems can thus be reduced. We show our results under the most general of assumptions.

Sinha, Abhinav

2011-01-01

372

Enhancement of the performance of a hybrid nonlinear vibration energy harvester based on piezoelectric and electromagnetic transductions  

NASA Astrophysics Data System (ADS)

A multiphysics model of a hybrid piezoelectric-electromagnetic vibration energy harvester (VEH), including the main sources of nonlinearities, is developed. The continuum problem is derived on the basis of the extended Hamilton principle, and the modal Galerkin decomposition method is used in order to obtain a reduced-order model consisting of a nonlinear Duffing equation of motion coupled with two transduction equations. The resulting system is solved analytically using the method of multiple time scales and numerically by means of the harmonic balance method coupled with the asymptotic numerical continuation technique. Closed-form expressions for the moving magnet critical amplitude and the critical load resistance are provided in order to allow evaluation of the linear dynamic range of the proposed device. Several numerical simulations have been performed to highlight the performance of the hybrid VEH. In particular, the power density and the frequency bandwidth can be boosted, by up to 60% and 29% respectively, compared to those for a VEH with pure magnetic levitation thanks to the nonlinear elastic guidance. Moreover, the hybrid transduction permits enhancement of the power density by up to 84%.

Mahmoudi, S.; Kacem, N.; Bouhaddi, N.

2014-07-01

373

Breezy Power: From Wind to Energy  

ERIC Educational Resources Information Center

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…

Claymier, Bob

2009-01-01

374

Fluid Power Systems. Energy Technology Series.  

ERIC Educational Resources Information Center

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…

Center for Occupational Research and Development, Inc., Waco, TX.

375

Power conditioning system for energy sources  

DOEpatents

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.

Mazumder, Sudip K. (Chicago, IL); Burra, Rajni K. (Chicago, IL); Acharya, Kaustuva (Chicago, IL)

2008-05-13

376

Potential energy scans and vibrational assignments of cyclopropanecarboxylic acid and cyclopropanecarboxamide.  

PubMed

The structural stability and internal rotations in cyclopropanecarboxylic acid and cyclopropanecarboxamide were investigated by the DFT-B3LYP and the ab initio MP2 calculations using 6-311G** and 6-311+G** basis sets. The computations were extended to the MP4//MP2/6-311G** and CCSD(T)//MP2/6-311G** single-point calculations. From the calculations the molecules were predicted to exist predominantly in the cis (C=O group eclipses the cyclopropane ring) with a cis-trans barrier of about 4-6kcal/mol. The OCOH torsional barrier in the acid was estimated to be about 12-13kcal/mol while the corresponding OCNH torsional barrier in the amide was calculated to be about 20kcal/mol. The equilibrium constant k for the cis<-->trans interconversion in cyclopropanecarboxylic acid was calculated to be 0.1729 at 298.15K that corresponds to an equilibrium mixture of about 85% cis and 15% trans. The vibrational frequencies were computed at the DFT-B3LYP level. Normal coordinate calculations were carried out and potential energy distributions were calculated for the low energy cis conformer of the molecules. Complete vibrational assignments were made on the basis of normal coordinate calculations and comparison with experimental data of the molecules. PMID:18599341

Badawi, H M; Al-Saadi, A A; Al-Khaldi, M A A; Al-Abbad, S A; Al-Sunaidi, Z H A

2008-12-15

377

An investigation into active vibration isolation based on predictive control: Part I: Energy source control  

NASA Astrophysics Data System (ADS)

We report the results of a recent study for the active vibration isolation with whole-spacecraft vibration isolation as an application background into which three parts are divided: (i) energy source control, (ii) nonlinearity and time delay, (iii) implementation and experiment. This paper is the first in this three-part series report, which presents theoretical and experimental investigations into pressure tracking system for energy source control of the isolator. Considering the special environment of the rocket and expected characteristics of actuators, where the isolator will be arranged between the rocket and the spacecraft, pneumatic actuator is proposed to realize the active isolation control. In order to improve the dynamic characteristics of the pneumatic isolator, a cascade control algorithm with double loop structure and predictive control algorithm for pressure tracking control of the inner loop are proposed. In the current paper, a pressure tracking control system using model predictive control (MPC) is studied first. A pneumatic model around pressure work point is built firstly by simplifying the flow equation of valve's orifices and pressure differential equation of the chambers. With this model, an MPC algorithm in the state space is developed, and problems including control parameter choice and command horizon generator are discussed in detail. In addition, by adding model error correction loop and velocity compensation feedback, effects of model uncertainty and volume variation of chambers are reduced greatly. Thus with this design, the real-time pressure tracking can be guaranteed, and so that the active control system can work at higher frequency range.

Fei, H. Z.; Zheng, G. T.; Liu, Z. G.

2006-09-01

378

Computation of high-energy vibrational eigenstates: Application to C6H5D  

NASA Astrophysics Data System (ADS)

In this study, a two loop iteration scheme, similar to one developed recently [Phys. Rev. E 51, 3643 (1995)], is applied to the computation of high energy vibrational eigenstates in 21-mode planar C6H5D. The computational method is based upon the use of a spectral filter to extract a small number of eigenpairs (near the test input energy E) from the interior of the dense energy spectrum. In the outer iteration loop, a very effective filter, the Green function G(E)=(E1-H)-1, is used to drive the Lanczos recursion algorithm through a small number of steps (frequently <10). The result is a small tridiagonal representation of the Green function. The Lanczos algorithm converges quickly because the desired eigenvalues, those near the test energy, are mapped to the extreme edges of the spectrum of the filter. In order to apply the Green function to the current Lanczos vector, a matrix partitioning technique is combined with a perturbation-iteration method in the inner iteration loop. The Green function-Lanczos algorithm, GFLA, was then used to compute eigenstates for 21-mode planar C6H5D near the energy of the v=3 CD overtone (about 6700 cm-1). These computations were done using an active space with the dimension 20 000. The resulting eigenfunctions were then subjected to several types of analysis, including basis state and vibrational mode distributions. It is shown that the energetic distribution of basis functions in the eigenvectors exhibits multifractal scaling (finer features built upon coarser features).

Wyatt, Robert E.

1995-11-01

379

Energy Servers Deliver Clean, Affordable Power  

NASA Technical Reports Server (NTRS)

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.

2010-01-01

380

Energy storage options for space power  

NASA Astrophysics Data System (ADS)

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.

Hoffman, H. W.; Martin, J. F.; Olszewski, M.

381

Energy storage options for space power  

SciTech Connect

Including energy storage in a space power supply enhances the feasibility of using thermal power cycles (Rankine or Brayton) and providing high-power pulses. Review of storage options (superconducting magnets, capacitors, electrochemical batteries, thermal phase-change materials (PCM), and flywheels) suggests 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 to 2000 kJ/kg at temperatures to 1675/sup 0/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 (approx. 550 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.

Hoffman, H.W.; Martin, J.F.; Olszewski, M.

1985-01-01

382

Three-dimensional analytic probabilities of coupled vibrational-rotational-translational energy transfer for DSMC modeling of nonequilibrium flows  

SciTech Connect

A three-dimensional, nonperturbative, semiclassical analytic model of vibrational energy transfer in collisions between a rotating diatomic molecule and an atom, and between two rotating diatomic molecules (Forced Harmonic Oscillator–Free Rotation model) has been extended to incorporate rotational relaxation and coupling between vibrational, translational, and rotational energy transfer. The model is based on analysis of semiclassical trajectories of rotating molecules interacting by a repulsive exponential atom-to-atom potential. The model predictions are compared with the results of three-dimensional close-coupled semiclassical trajectory calculations using the same potential energy surface. The comparison demonstrates good agreement between analytic and numerical probabilities of rotational and vibrational energy transfer processes, over a wide range of total collision energies, rotational energies, and impact parameter. The model predicts probabilities of single-quantum and multi-quantum vibrational-rotational transitions and is applicable up to very high collision energies and quantum numbers. Closed-form analytic expressions for these transition probabilities lend themselves to straightforward incorporation into DSMC nonequilibrium flow codes.

Adamovich, Igor V. [Nonequilibrium Thermodynamics Laboratory, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)] [Nonequilibrium Thermodynamics Laboratory, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

2014-04-15

383

Lumped parameter models of vortex induced vibration with application to the design of aquatic energy harvester  

NASA Astrophysics Data System (ADS)

In the present study, a lumped parameter model for vortex-induced vibrations is analysed. In this work, the vortex-induced vibrations of an elastically mounted rigid cylinder are able to move in-line and transverse to the flow with equal mass ratio and natural frequencies. A simplified lumped mass model is proposed to study the two degree of freedom (dof) structural oscillator. A classical van der Pol equation along with acceleration coupling, models the near wake dynamics describing the fluctuating nature of vortex shedding. The model dynamics is investigated analytically and the results are compared for moderate mass ratios. The results predicted using this model show a good agreement with the experimental data. The dependence of stream-wise displacement on mass and damping is explored. The cause of cross-flow displacement magnification due to freedom to move in stream-wise direction is also explored using the proposed model. Apart from these two degrees of freedom, the cylinder can also undergo rotation about its centre of mass. The effect of freedom to move in this rotational degree of freedom is exploited to our advantage by applying it to the VIVACE (Vortex induced vibration aquatic clean energy) design which was originally proposed by Bernitsas et al. (2008). The original design was not reported to be the optimal one and the set-up was shown to work only for a given flow velocity. But, the flow environment keeps changing and hence there is a need to bring in robustness and optimize the proposed design. The values of optimized spring stiffness have been found using the lumped mass model. The design is made robust by exploiting the rotational mode. This mode is triggered by varying the overhang lengths in accordance with the varying flow velocity in order to strike resonance for a certain flow regime.

Dhanwani, Manish A.; Sarkar, Abhijit; Patnaik, B. S. V.

2013-11-01

384

High resolution proton energy loss spectroscopy of the high overtone vibrations in CF4  

NASA Astrophysics Data System (ADS)

Proton energy loss spectroscopy (PELS) has been used to investigate the very high overtone states of the ?3 mode in CF4. With a new scattering apparatus, which is described here in detail, it has been possible to directly measure the energy levels of the dominantly excited ?3 mode up to its 14th overtone with an energy resolution of ?E=10-15 meV, corresponding to 80-120 cm-1. The data are interpreted using the Hecht vibrational Hamiltonian which predicts the tensor splitting of the ?3 mode energy levels into sublevel bands. By adjusting the values of the anharmonicity parameters X33, G33, and T33, previously determined by IR spectroscopy and introducing a second-order anharmonicity parameter X333, it was possible to fit the ?3 mode energy levels to the measured energy loss distributions. A model based on the earlier theoretical work of Levene and Perry [H. B. Levene and D. Perry, J. Chem. Phys. 84, 4385 (1986)] for the proton-CF4 scattering process is extended to allow the simulation of complete spectra including contributions from combinations with the ?1 and ?4 mode for comparison with the experimental energy loss spectra. The influence of all relevant parameters on the simulated data is analyzed in detail.

Maring, W.; Toennies, J. P.; Wang, R. G.; Levene, H. B.

1995-07-01

385

Harvesting microalgal biomass using a magnetically induced membrane vibration (MMV) system: filtration performance and energy consumption.  

PubMed

This study was performed to investigate the effectiveness of submerged microfiltration to harvest both a marine diatom Phaeodactylum tricornutum and a Chlorella vulgaris in a recently developed magnetically induced membrane vibrating (MMV) system. We assess the filtration performance by conducting the improved flux step method (IFM), fed-batch concentration filtrations and membrane fouling autopsy using two lab-made membranes with different porosity. The full-scale energy consumption was also estimated. Overall results suggest that the MMV offers a good fouling control and the process was proven to be economically attractive. By combining the membrane filtration (15× concentration) with centrifugation to reach a final concentration of 25% w/v, the energy consumption to harvest P. tricornutum and C. vulgaris was, respectively, as low as 0.84 and 0.77kWh/m(3), corresponding to 1.46 and 1.39 kWh/kg of the harvested biomass. PMID:23624051

Bilad, M R; Discart, V; Vandamme, D; Foubert, I; Muylaert, K; Vankelecom, Ivo F J

2013-06-01

386

Vibration Testing of an Operating Stirling Convertor  

NASA Technical Reports Server (NTRS)

The NASA John H. Glenn Research Center and the U.S. Department of Energy are currently developing a Stirling convertor for use as an advanced spacecraft power system for future NASA deep-space missions. As part of this development, a Stirling Technology Demonstrator Convertor (TDC) was recently tested to verify its survivability and capability of withstanding its expected launch random vibration environment. The TDC was fully operational (producing power) during the random vibration testing. The output power of the convertor was measured during the testing, and these results are discussed in this paper. Numerous accelerometers and force gauges were also present which provided information on the dynamic characteristics of the TDC and an indication of any possible damage due to vibration. These measurements will also be discussed in this paper. The vibration testing of the Stirling TDC was extremely successful. The TDC survived all its vibration testing with no structural damage or functional performance degradation. As a result of this testing, the Stirling convertor's capability to withstand vibration has been demonstrated, enabling its usage in future spacecraft power systems.

Hughes, William O.; McNelis, Mark E.; Goodnight, Thomas W.

2000-01-01

387

Broadband energy harvesting by exploiting nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate  

NASA Astrophysics Data System (ADS)

Recently bistable composite laminates have been investigated for broadband energy harvesting, by taking advantage of their nonlinear oscillations around the first vibration mode. However, it has been reported that the excitation acceleration needed for the desired large amplitude limit cycle oscillation is too high, if the first vibration mode is elevated to relative higher frequencies (60 Hz e.g.). This study investigates the feasibility of exploiting the nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate (RPBL), for broadband vibration energy harvesting at relative higher frequencies, but with relative low excitation acceleration. The proposed RPBL has three oscillation patterns around the second vibration mode, including single-well oscillation, chaotic intermittency oscillation and limit cycle oscillation. The broadband characteristics and the considerable energy conversion efficiency of the RPBL are demonstrated in experiments. The static nonlinearity and the dynamic responses of the RPBL are investigated by finite element method. Finite element analysis (FEA) reveals that the enhanced dynamic responses of the RPBL are due to its softening bending stiffness and the local snap through phenomenon. The FEA results coincide reasonably well with experimental results.

Li, Hao; Dai, Fuhong; Du, Shanyi

2015-04-01

388

Relaxation dynamics in quantum dissipative systems: the microscopic effect of intramolecular vibrational energy redistribution.  

PubMed

We investigate the effect of inter-mode coupling on the vibrational relaxation dynamics of molecules in weak dissipative environments. The simulations are performed within the reduced density matrix formalism in the Markovian regime, assuming a Lindblad form for the system-bath interaction. The prototypical two-dimensional model system representing two CO molecules approaching a Cu(100) surface is adapted from an ab initio potential, while the diatom-diatom vibrational coupling strength is systematically varied. In the weak system-bath coupling limit and at low temperatures, only first order non-adiabatic uni-modal coupling terms contribute to surface-mediated vibrational relaxation. Since dissipative dynamics is non-unitary, the choice of representation will affect the evolution of the reduced density matrix. Two alternative representations for computing the relaxation rates and the associated operators are thus compared: the fully coupled spectral basis, and a factorizable ansatz. The former is well-established and serves as a benchmark for the solution of Liouville-von Neumann equation. In the latter, a contracted grid basis of potential-optimized discrete variable representation is tailored to incorporate most of the inter-mode coupling, while the Lindblad operators are represented as tensor products of one-dimensional operators, for consistency. This procedure results in a marked reduction of the grid size and in a much more advantageous scaling of the computational cost with respect to the increase of the dimensionality of the system. The factorizable method is found to provide an accurate description of the dissipative quantum dynamics of the model system, specifically of the time evolution of the state populations and of the probability density distribution of the molecular wave packet. The influence of intra-molecular vibrational energy redistribution appears to be properly taken into account by the new model on the whole range of coupling strengths. It demontrates that most of the mode mixing during relaxation is due to the potential part of the Hamiltonian and not to the coupling among relaxation operators. PMID:25149802

Uranga-Piña, L; Tremblay, J C

2014-08-21

389

Extracting energy from a flow: An asymptotic approach using vortex-induced vibrations and feedback control  

NASA Astrophysics Data System (ADS)

This paper considers vortex-induced vibrations of a cylinder in water streams for renewable energy production. We use an analytical model recently obtained by the authors from the asymptotic analysis of a coupled flow-cylinder system, and assess the ability of a control velocity applied at the cylinder wall to optimize the magnitude of dissipated energy at disposal to be harvested. The retained approach is that of proportional feedback control. When the system evolves on its limit cycle, we show that the control yields an increase in the mean dissipated energy by 3.5%, as well as a significant improvement of the robustness with respect to small inaccuracies of the structural parameters. However, we also show that the system is susceptible to converge to cycles of lower energy when subjected to external disturbances, as a result of the simultaneous existence of multiple stable cycles. Consequently, we propose a transient control algorithm meant to force the return of the system to its optimal cycle. Its efficiency is assessed for two feedback approaches relying on distinct types of measurements: we find significant differences in the time needed to reach convergence to the optimal cycle, which ultimately results in energy being spent when feedback is designed from cylinder measurements, and in energy being harnessed when feedback is designed from flow measurements.

Meliga, Philippe; Chomaz, Jean-Marc; Gallaire, François

2011-07-01

390

Accurate variational calculations and analysis of the HOCl vibrational energy spectrum  

NASA Astrophysics Data System (ADS)

Large scale variational calculations for the vibrational states of HOCl are performed using a recently developed, accurate ab initio potential energy surface. Three different approaches for obtaining vibrational states are employed and contrasted; a truncation/recoupling scheme with direct diagonalization, the Lanczos method, and Chebyshev iteration with filter diagonalization. The complete spectrum of bound states for nonrotating HOCl is computed and analyzed within a random matrix theory framework. This analysis indicates almost entirely regular dynamics with only a small degree of chaos. The nearly regular spectral structure allows us to make assignments for the most significant part of the spectrum, based on analysis of coordinate expectation values and eigenfunctions. Ground state dipole moments and dipole transition probabilities are also calculated using accurate ab initio data. Computed values are in good agreement with available experimental data. Some exact rovibrational calculations for J=1, including Coriolis coupling, are performed. The exact results are nearly identical with those obtained from the adiabatic rotation approximation and very close to those from the centrifugal sudden approximation, thus indicating a very small degree of asymmetry and Coriolis coupling for the HOCl molecule.

Skokov, Sergei; Qi, Jianxin; Bowman, Joel M.; Yang, Chao-Yie; Gray, Stephen K.; Peterson, Kirk A.; Mandelshtam, Vladimir A.

1998-12-01

391

Experiments on active control of vibrational power flow using piezoceramic actuators and sensors  

NASA Technical Reports Server (NTRS)

The active control of flexural power flow in both semiinfinite and finite elastic beams is experimentally investigated. The experimental results demonstrate that piezoceramic transducers when used in conjunction with an adaptive least mean squares controller, can effectively control flexural power flow in thin beam systems. The piezoceramic transducers offer distinct size and weight advantages over conventional transducers. The experiments also demonstrate the use of an axial scanning laser vibrometer to determine out of plane velocity and power flow.

Gibbs, Gary P.; Fuller, Chris R.

1990-01-01

392

Power Generation Characteristics of Single Electrode Output Circuit in Electret Energy Harvester  

NASA Astrophysics Data System (ADS)

This paper reports the new output circuit using a single electrode in electret energy harvester, and proves that the single electrode is able to generate output power on grounded load. 3D numerical model of gap-closing type electret energy harvester is presented, and power generation characteristics are analysed and verified. Results show that the two electrodes are actually two independent current sources. Single electrode output circuit has two merits: when only one electrode is connected, it reduces wiring difficulty; when both electrodes are connected to grounded load respectively, it doubles output power compared with traditional output circuit. Using proposed circuit, maximal total power of 30mm×20mm prototype reaches 154.5?W@10Hz, 1.8mm sinusoidal vibration, and an LED has been successfully lighted up.

Bu, L.; Xu, H. Y.; Xu, B. J.; Song, L.

2014-11-01

393

Electron hole pair mediated vibrational excitation in CO scattering from Au(111): Incidence energy and surface temperature dependence  

SciTech Connect

We investigated the translational incidence energy (E{sub i}) and surface temperature (T{sub s}) dependence of CO vibrational excitation upon scattering from a clean Au(111) surface. We report absolute v = 0 ? 1 excitation probabilities for E{sub i} between 0.16 and 0.84 eV and T{sub s} between 473 and 973 K. This is now only the second collision system where such comprehensive measurements are available – the first is NO on Au(111). For CO on Au(111), vibrational excitation occurs via direct inelastic scattering through electron hole pair mediated energy transfer – it is enhanced by incidence translation and the electronically non-adiabatic coupling is about 5 times weaker than in NO scattering from Au(111). Vibrational excitation via the trapping desorption channel dominates at E{sub i} = 0.16 eV and quickly disappears at higher E{sub i}.

Shirhatti, Pranav R.; Werdecker, Jörn; Golibrzuch, Kai; Wodtke, Alec M.; Bartels, Christof, E-mail: cbartel@gwdg.de [Institute for Physical Chemistry, Georg August University of Göttingen, 37077 Göttingen (Germany); Max Planck Institute for Biophysical Chemistry, 37077 Göttingen (Germany)

2014-09-28

394

Role of energy exchange in vibrational dephasing processes in liquids and solids  

SciTech Connect

Three theories which claim relevance to the dephasing of molecular vibrations in condensed phase matter are presented. All of these theories predict (in certain limiting cases) that the widths and shifts of molecular vibrations will obey an Arrhenius temperature dependence. The basic tenets of the theories are detailed so that the differences between them may be used in an experiment to distinguish between them. One model, based on intermolecular energy exchange of low-frequency modes, results in dephasing the high-frequency modes when anharmonic coupling is present. A computer analysis of temperature dependent experimental lineshapes can result in the extraction of various parameters such as the anharmonic shifts and the exchange rates. It is shown that, in order to properly assess the relative validity of the three models, other evidence must be obtained such as the spectral parameters of the low-frequency modes, the combination bands, and the isotopic dilution behavior. This evidence is presented for d/sub 14/-durene (perdeutero-1,2,4,5-tetramethylbenzene) and compared to previous data obtained on pure h/sub 14/-durene. An extension of the (HSC) intermolecular energy exchange model which allows for the possibility of partial delocalization of the low-frequency modes gives an adequate description of the experimental evidence. Isotopic dilution experiments, in particular, have resulted in a detailed picture of the energy transfer dynamics of the low-frequency modes. A section in which some spontaneous Raman spectra support a model of inhomogeneous broadening in liquids based on results of picosecond stimulated Raman spectroscopy is presented. The model is that a distribution of environmental sites is created by a distribution in the local density and thus creates inhomogeneous broadening.

Marks, S.

1981-08-01

395

Energy saving potential of office equipment power management  

Microsoft Academic Search

While many studies have estimated the energy saving potential of office equipment power management, there is no recent study about the energy saving potential of shortening the power management delay time. In this paper, we estimated the energy saving potential of the complete saturation of power management, and also the additional energy saving potential of shortening the power management delay

Kaoru Kawamoto; Yoshiyuki Shimoda; Minoru Mizuno

2004-01-01

396

Direct evidence for mode-specific vibrational energy relaxation from quantum time-dependent perturbation theory. III. The 4 and 7 modes of  

E-print Network

Direct evidence for mode-specific vibrational energy relaxation from quantum time-dependent perturbation theory. III. The 4 and 7 modes of nonplanar nickel porphyrin models Yong Zhang and John E. Straub://jcp.aip.org/about/rights_and_permissions #12;Direct evidence for mode-specific vibrational energy relaxation from quantum time

Straub, John E.

397

Direct evidence for mode-specific vibrational energy relaxation from quantum time-dependent perturbation theory. II. The 4 and 7 modes of  

E-print Network

Direct evidence for mode-specific vibrational energy relaxation from quantum time-dependent perturbation theory. II. The 4 and 7 modes of iron-protoporphyrin IX and iron porphine Yong Zhang and John E://jcp.aip.org/about/rights_and_permissions #12;Direct evidence for mode-specific vibrational energy relaxation from quantum time

Straub, John E.

398

Vibrational spectroscopy in the electron microscope  

NASA Astrophysics Data System (ADS)

Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for `aloof' spectroscopy that largely avoids radiation damage.

Krivanek, Ondrej L.; Lovejoy, Tracy C.; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R. W.; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E.; Lagos, Maureen J.; Egerton, Ray F.; Crozier, Peter A.

2014-10-01

399

A Study on Design and Analysis of Hybrid Vibration Damper with Energy Harvesting and Optimal Damping Effect  

NASA Astrophysics Data System (ADS)

The basic purpose of a damper is to reduce the vibration and to have a better ride comfort, road handling and safety to the rider. Recent developments show that an active vibration damper can effectively work much better than a passive damper. The effectiveness and reliability can be further enhanced by using hybrid dampers, which is a combination of active and passive dampers. But the need to have energy optimization in any field need not be stressed. Consequently, novel suspension concepts are required, not only to improve the vehicle's dynamic performance, but also to see that the energy generated during vibration can be harvested by utilizing regeneration functions. Hence if a hybrid damper with energy harvesting capability be designed, it would serve both purposes. In the hybrid damper a combination of hydraulic damper to act as a passive damper and an electromagnetic (EM) damper to act as an active damper is considered. The hydraulic system has more reliability and is time tested and the EM system acts as a dynamic vibration system as well as energy harvester. In this study a hybrid EM damper is modeled, analyzed and validity is shown for frequency response functions and energy balance for its active use. It is also shown how the effectiveness of the suspension system can be enhanced by using a hybrid damper.

Hanumantha Rao, T. V.; Srinivasa Rao, M. S. S.; Apparao, B. V.; Satyanarayana, K.

2014-04-01

400

A compilation of spacecraft loads data from four Titan Centaur launch vehicle flights. Volume 2, part 1: Vibration power spectral density analysis of launch and max Q flight  

NASA Technical Reports Server (NTRS)

Summary plots are presented for the time histories and power spectral density analyses of vibration and acceleration on the spacecraft from the Titan Centaur launchings carrying the Viking dynamic simulator and the two Viking spacecraft (TC-1, TC-3 and TC-4).

Kachadourian, G. (compiler)

1977-01-01

401

Simulation of shaft vibrations due to interaction between turbine-generator train and power electronic converters at the Visund oil platform  

Microsoft Academic Search

The Norwegian company Norsk Hydro AS has frequently experienced severe vibration problems within the power generator trains at some of their oil platforms in the North Sea. Initially, these problems were believed to have a pure mechanical nature. The generator shaft was therefore modified to increase its inherent damping, but this only partly solved the problem. The focus was eventually

M. Hernes; B. Gustavsen

2002-01-01

402

Powerful low-frequency vibrators and outlooks of their application at monitoring of engineering constructions and at solving other problems of active seismology  

SciTech Connect

In the past two decades, active seismology studies in Russia have made use of powerful (40- and 100-ton) low-frequency vibrators. These sources create a force amplitude of up to 100 tons and function in the 1.5-3, 3-6 and 5-10 Hz frequency bands. The mobile versions of the vibrator have a force amplitude of 40 tons and a 6-12 Hz frequency band. Registration distances for the 100 ton vibrator are as large as 350 km, enabling the refracted waves to penetrate down to 50 km depths. Vibrator operation sessions are highly repeatable, having distinct ''summer'' or ''winter'' spectral patterns. A long profile of seismic records allows estimating of fault zone depths using changes in recorded spectra. Other applications include deep seismic profiling, seismic hazard mapping, structural testing, stress induced anisotropy studies, seismic station calibration, and large-structure integrity testing. In more detail, these questions are discussed in reports of our colleagues from Novosibirsk. This report is devoted mainly to powerful low-frequency vibrators, their theoretical description and design. Besides, problems of vibroseismic monitoring of engineering constructions are briefly elucidated.

Alekseev, A. S.; Chichinin, I. S.; Korneev, V. A.; Komissarov, V. V.; Seleznev, V. S.; Emanov, A. F.

2004-06-11

403

Novel Nuclear Powered Photocatalytic Energy Conversion  

SciTech Connect

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 fabrication of a range of new cell materials and geometries at Konarka's manufacturing facilities, and the irradiation testing and evaluation of these new cell designs within the UML Radiation Laboratory. The primary focus of all this work was to establish the proof of concept of the basic gammavoltaic principle using a new class of dye-sensitized photon converter (DSPC) materials based on KTI's original DSSC design. In achieving this goal, this report clearly establishes the viability of the basic gammavoltaic energy conversion concept, yet it also identifies a set of challenges that must be met for practical implementation of this new technology.

White,John R.; Kinsmen,Douglas; Regan,Thomas M.; Bobek,Leo M.

2005-08-29

404

Shock and Vibration Testing of an AMB Supported Energy Storage Flywheel  

NASA Astrophysics Data System (ADS)

Shock and vibration testing of an Active Magnetic Bearing (AMB) supported energy storage flywheel is presented. The flywheel is under development at the University of Texas-Center for Electromechanics (UT-CEM) for application in a transit bus. The flywheel is gimbal mounted to reduce the gyroscopic forces transmitted to the magnetic bearings during pitching and rolling motions of the bus. The system was placed on a hydraulic terrain simulator and driven through pitch, roll and shock motions equivalent to 150% of maximum expected bus frame values. Although the AMB control approach was originally developed specifically to ensure rotordynamic stability, relative rotor/housing motion was typically less than half of the backup bearing clearance under all tested conditions. Test results are presented and compared to analytical predictions for the 35000rpm nominal operating speed. The impact of the AMB control algorithm is discussed relative to the input forcing function.

Hawkins, Lawrence; Murphy, Brian; Zierer, Joseph; Hayes, Richard

405

Peroxyacetyl radical: Electronic excitation energies, fundamental vibrational frequencies, and symmetry breaking in the first excited state  

NASA Astrophysics Data System (ADS)

Peroxyacetyl radical [CH3C(O)O2] is among the most abundant peroxy radicals in the atmosphere and is involved in OH-radical recycling along with peroxyacetyl nitrate formation. Herein, the ground ( X ˜ ) and first ( A ˜ ) excited state surfaces of cis and trans peroxyacetyl radical are characterized using high-level ab initio methods. Geometries, anharmonic vibrational frequencies, and adiabatic excitation energies extrapolated to the complete basis-set limit are reported from computations with coupled-cluster theory. Excitation of the trans conformer is found to induce a symmetry-breaking conformational change due to second-order Jahn-Teller interactions with higher-lying excited states. Additional benchmark computations are provided to aid future theoretical work on peroxy radicals.

Copan, Andreas V.; Wiens, Avery E.; Nowara, Ewa M.; Schaefer, Henry F.; Agarwal, Jay

2015-02-01

406

Rotor hub vibration and blade loads reduction, and energy harvesting via embedded radial oscillator  

NASA Astrophysics Data System (ADS)

An embedded radial absorber is investigated to control helicopter rotor hub vibration and blade loads. The absorber is modeled as a discrete mass moving in the spanwise direction within the blade. The absorber is retained in place and tuned with a spring and a damper. The radial absorber couples with lead-lag dynamic through Coriolis forces. The embedded radial absorber coupled to the helicopter is analyzed with a comprehensive rotorcraft model. The blade is modeled as an elastic beam undergoing flap bending, lag bending and elastic torsion, and a radial degree of freedom is added for the absorber. The tuning of the embedded radial absorber to a frequency close to 3/rev with no damping is shown to reduce significantly (up to 86%) the 4/rev in-plane hub forces of a 4-bladed hingeless rotor similar to a MBB BO-105 in high speed flight. The simulation shows that the absorber modifies the in-plane blade root shears to synchronize them to cancel each other in the transmission from rotating frame to fixed frame. A design of an embedded radial absorber experiment for hub vibration control is presented and it is concluded that for such high tuning frequencies as 3/rev, it is feasible to use a regular coil spring to compensate for the steady centrifugal force. Large reduction of blade lag shear (85%) and lag bending moment (71%) is achieved by tuning the embedded radial absorber close to 1/rev (also shown for a BO-105 like helicopter in high speed flight). The absorber reduces the amplitude of the lag bending moment at 1/rev, thus reducing the blade lead-lag motion and reducing the blade drag shear and lag bending moment. Finally, the use of the embedded radial absorber is investigated as a source electrical power when combined with an electromagnetic circuit. A model of the electromagnetic system is developed and validated, and an evaluation of the amount of power harvestable for different configurations is presented. The maximum power harvested was calculated to be 133 watts.

Austruy, Julien

407

Anharmonic Effects on the Electron-Energy Spectra of Surface Vibrations  

NASA Astrophysics Data System (ADS)

First, we consider the effect of lateral interactions on double losses and overtones in electron-energy-loss studies of surface vibrations. We develop a theory of two-phonon losses in the dipole-dominated regime of small -angle scattering. Our calculation employs the simple model of an ordered overlayer of molecules adsorbed on a crystal surface. With this model, we can identify two features; one which corresponds to the double loss and another which corresponds the excitation of an overtone. We then study the role of lateral interactions in each. We find that the presence of lateral interactions affects the position of the overtone relative to the double loss, and influences both its width and shape. The implications of these results are discussed, particularly as they relate to estimates of dissociation energies by the Birge-Sponer procedure. Next, we consider the anharmonic damping of adsorbate vibrations, with specific applications to species (S, O, and CO) adsorbed on the Ni(100) and Ni(111) surfaces. Our attention is restricted to adsorbate modes that can decay by two-phonon processes to one substrate phonon and either another substrate mode phonon or to a phonon of a mode that is localized on the adsorbate. The magnitude and temperature variation of the linewidth of adsorbate modes by this mechanism is explored; we find that near room temperature the calculated linewidths vary linearly with temperature. We also simulate the inhomogeneous broadening produced by disorder by considering the eigenfrequencies of infrared -active modes. Finally, we consider the diffuse scattering of electrons from surfaces by long-wavelength, acoustic phonons. The mechanism that we explore is the modulation of the image potential from ripples induced in the surface profile by thermally-excited surface and bulk phonons. We compare our results with earlier studies, and with the scattering produced by the dynamic-dipole moment of the surface atoms.

Ariyasu, Janice Carol

408

Tower Power: Producing Fuels from Solar Energy  

ERIC Educational Resources Information Center

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)

Antal, M. J., Jr.

1976-01-01

409

Active power filter with hybrid energy storage  

Microsoft Academic Search

An active power filter that uses an impressed current converter and an inductive-capacitive energy storage circuit is presented. This storage includes a switching section to interface the inductive and capacitive element. This solution allows independent choice of the converter configuration and of the type of storage system which, in this particular case, is mainly capacitive. The theory of operation is

L. Malesani; L. Rossetto; P. Tenti

1991-01-01

410

Volume 76. number 1 CHEMICAL PHYSICS LETTERS 15 November 1980 THE KINETICS OF VIBRATIONAL ENERGY TRANSFER AND RELAXATION PROCESSES  

E-print Network

Volume 76. number 1 CHEMICAL PHYSICS LETTERS 15 November 1980 THE KINETICS OF VIBRATIONAL ENERGY to be the overtones of v3 of which the iirst overtone transltlon has a large oscillator strength and is there- fore was connected to a glass vacuum syste

Apkarian, V. Ara

411

Direct evidence for mode-specific vibrational energy relaxation from quantum time-dependent perturbation theory. I. Five-coordinate  

E-print Network

Direct evidence for mode-specific vibrational energy relaxation from quantum time 2008; accepted 3 December 2008; published online 13 January 2009 The time scales and mechanisms of mode-Markovian time-dependent perturbation theory and density functional theory calculation. Seven normal modes

Straub, John E.

412

Quantum theory of vibrational, rotational, and translational energy exchange in collisions of polyatomic molecules. Application to methyl halides  

Microsoft Academic Search

We derive a quantum theory of inter- and intramolecular transfer of vibrational, rotational, and translational energy in collisions of polyatomic molecules, in the case that short range forces between the collision partners are of prevailing importance. For this purpose, we first transform the Hamiltonian into the form which enables us to eliminate the coordinates which are cyclic in the limit

Adolf Miklavc

1983-01-01

413

Direct calculation of anharmonic vibrational states of polyatomic molecules using potential energy surfaces calculated from density functional theory  

NASA Astrophysics Data System (ADS)

Potential energy surface points computed from variants of density functional theory (DFT) are used to calculate directly the anharmonic vibrational frequencies of H2O, Cl-H2O, and (H2O)2. The method is an adaptation to DFT of a recent algorithm for direct calculations of anharmonic vibrational frequencies using ab initio electronic structure codes. The DFT calculations are performed using the BLYP and the B3LYP functionals and the results are compared with experiment, and also with those calculated directly from a potential energy surface obtained using ab initio Möller-Plesset second-order perturbation theory (MP2). The direct calculation of the vibrational states from the potential energy points is performed using the correlation-corrected vibrational self-consistent field (CC-VSCF) method. This method includes anharmonicity and correlations between different vibrational modes. The accuracy of this method is examined and it is shown that for the experimentally measured transitions the errors in the CC-VSCF calculations are much less than the errors due to the potential energy surface. By comparison with the experimentally measured frequencies the CC-VSCF method thus provides a test for the quality of the potential energy surfaces. The results obtained with the B3LYP functional, in contrast to those of the BLYP functional, are of comparable quality to those obtained with MP2. The B3LYP anharmonic frequencies are in good agreement with experiment, showing this DFT method describes well the anharmonic part of the potential energy surface. The BLYP results systematically underestimate both the harmonic and anharmonic frequencies and indicate that using this functional for the description of hydrogen-bonded systems may cause significant errors.

Wright, Nicholas J.; Gerber, R. Benny

2000-02-01

414

Vibrational spectra, theoretical calculations, and two-dimensional potential energy surface for the ring-puckering vibrations of 2,4,7-trioxa[3.3.0]octane.  

PubMed

2,4,7-Trioxa[3.3.0]octane (247TOO) is an unusual bicyclic molecule which can exist in four different conformational forms which are determined by the directions of the two ring- puckering motions. The vibrational assignments of 247TOO have been made based on its infrared and Raman spectra and theoretical density functional theory (DFT) calculations. The two ring-puckering motions (in-phase and out-of-phase) were observed in the Raman spectra of the liquid at 249 and 205 cm(-1) and these values correspond well to the DFT values of 247 and 198 cm(-1). Ab initio calculations were utilized to calculate the structures and conformational energies for the four energy minima and the barriers to interconversion and the data was utilized to generate a two-dimensional potential energy surface (PES) for the two ring-puckering motions. The resulting quantum state energies for this PES were then calculated in order to better understand the patterns that are produced when the PES has four energy minima at different energy values. The wave functions corresponding to the different quantum states were also calculated. The NMR spectrum of 247TOO showed the presence of the two lowest energy conformations, consistent with the results of the ab initio calculations. PMID:25514365

Chun, Hye Jin; Meinander, Niklas; Villarreal, John R; Laane, Jaan

2015-01-15

415

Energy Storage System Sizing for Smoothing Power Generation , P. Bydlowski  

E-print Network

Energy Storage System Sizing for Smoothing Power Generation of Direct J. Aubry1 , P. Bydlowski 1 E-mail: judicael.aubry Abstract This paper examines the sizing energy storage system (ESS) for energy converter. Keywords: Energy Storage System (ESS), power smoothing, Direct Wave Energy Converter, Supercapacitor, Power

Boyer, Edmond

416

Nuclear Power and the World's Energy Requirements  

E-print Network

The global requirements for energy are increasing rapidly as the global population increases and the under-developed nations become more advanced. The traditional fuels used in their traditional ways will become increasingly unable to meet the demand. The need for a review of the energy sources available is paramount, although the subsequent need to develop a realistic strategy to deal with all local and global energy requirements is almost as important. Here attention will be restricted to examining some of the claims and problems of using nuclear power to attempt to solve this major question.

V. Castellano; R. F. Evans; J. Dunning-Davies

2004-06-10

417

Non-equilibrium vibrational and electron energy distributions functions in atmospheric nitrogen ns pulsed discharges and \\mus post-discharges: the role of electron molecule vibrational excitation scaling-laws  

E-print Network

The formation of the electron energy distribution function in nanosecond atmospheric nitrogen discharges is investigated by means of self-consistent solution of the chemical kinetics and the Boltzmann equation for free electrons. The post-discharge phase is followed to few microseconds. The model is formulated in order to investigate the role of the cross section set, focusing on the vibrational-excitation by electron-impact through resonant channel. Four different cross section sets are considered, one based on internally consistent vibrational-excitation calculations which extend to the whole vibrational ladder, and the others obtained by applying commonly used scaling-laws.

Colonna, Gianpiero; Celiberto, Roberto; Capitelli, Mario; Tennyson, Jonathan

2015-01-01

418

Measurement of vibrational spectrum of liquid using monochromated scanning transmission electron microscopy-electron energy loss spectroscopy.  

PubMed

Investigations on the dynamic behavior of molecules in liquids at high spatial resolution are greatly desired because localized regions, such as solid-liquid interfaces or sites of reacting molecules, have assumed increasing importance with respect to improving material performance. In application to liquids, electron energy loss spectroscopy (EELS) observed with transmission electron microscopy (TEM) is a promising analytical technique with the appropriate resolutions. In this study, we obtained EELS spectra from an ionic liquid, 1-ethyl-3-methylimidazolium bis (trifluoromethyl-sulfonyl) imide (C2mim-TFSI), chosen as the sampled liquid, using monochromated scanning TEM (STEM). The molecular vibrational spectrum and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap of the liquid were investigated. The HOMO-LUMO gap measurement coincided with that obtained from the ultraviolet-visible spectrum. A shoulder in the spectrum observed ?0.4 eV is believed to originate from the molecular vibration. From a separately performed infrared observation and first-principles calculations, we found that this shoulder coincided with the vibrational peak attributed to the C-H stretching vibration of the [C2mim(+)] cation. This study demonstrates that a vibrational peak for a liquid can be observed using monochromated STEM-EELS, and leads one to expect observations of chemical reactions or aids in the analysis of the dynamic behavior of molecules in liquid. PMID:25015973

Miyata, Tomohiro; Fukuyama, Mao; Hibara, Akihide; Okunishi, Eiji; Mukai, Masaki; Mizoguchi, Teruyasu

2014-10-01

419

Energy storage for hybrid remote power systems  

SciTech Connect

Energy storage can be a cost-effective component of hybrid remote power systems. Storage serves the special role of taking advantage of intermittent renewable power sources. Traditionally this role has been played by lead-acid batteries, which have high life-cycle costs and pose special disposal problems. Hydrogen or zinc-air storage technologies can reduce life-cycle costs and environmental impacts. Using projected data for advanced energy storage technologies, LLNL ran an optimization for a hypothetical Arctic community with a reasonable wind resource (average wind speed 8 m/s). These simulations showed the life-cycle annualized cost of the total energy system (electric plus space heating) might be reduced by nearly 40% simply by adding wind power to the diesel system. An additional 20 to 40% of the wind-diesel cost might be saved by adding hydrogen storage or zinc-air fuel cells to the system. Hydrogen produced by electrolysis of water using intermittent, renewable power provides inexpensive long-term energy storage. Conversion back to electricity with fuel cells can be accomplished with available technology. The advantages of a hydrogen electrolysis/fuel cell system include low life-cycle costs for long term storage, no emissions of concern, quiet operation, high reliability with low maintenance, and flexibility to use hydrogen as a direct fuel (heating, transportation). Disadvantages include high capital costs, relatively low electrical turn-around efficiency, and lack of operating experience in utility settings. Zinc-air fuel cells can lower capital and life-cycle costs compared to hydrogen, with most of the same advantages. Like hydrogen systems, zinc-air technology promises a closed system for long-term storage of energy from intermittent sources. The turn around efficiency is expected to exceed 60%, while use of waste heat can potentially increase overall energy efficiency to over 80%.

Isherwood, W., LLNL

1998-03-01

420

Assistance of molecular vibrations on coherent energy transfer in photosynthesis from the view of a quantum heat engine.  

PubMed

Recently, the quantum nature in the energy transport in solar cells and light-harvesting complexes has attracted much attention as being triggered by the experimental observations. We model the light-harvesting complex (i.e., PEB50 dimer) as a quantum heat engine (QHE) and study the effect of the undamped intramolecule vibrational modes on the coherent energy-transfer process and quantum transport. We find that the exciton-vibration interaction has nontrivial contribution to the promotion of quantum yield as well as transport properties of the QHE at steady state by enhancing the quantum coherence quantified by entanglement entropy. The perfect quantum yield over 90% has been obtained, with the exciton-vibration coupling. We attribute these improvements to the renormalization of the electronic couplings effectively induced by exciton-vibration interaction and the subsequent delocalization of excitons. Finally, we demonstrate that the thermal relaxation and dephasing can help the excitation energy transfer in the PEB50 dimer. PMID:25776946

Zhang, Zhedong; Wang, Jin

2015-04-01

421

Accurate ab initio and ``hybrid'' potential energy surfaces, intramolecular vibrational energies, and classical ir spectrum of the water dimer  

NASA Astrophysics Data System (ADS)

We report three modifications to recent ab initio, full-dimensional potential energy surfaces (PESs) for the water dimer [X. Huang et al., J. Chem. Phys. 128, 034312 (2008)]. The first modification is a refit of ab initio electronic energies to produce an accurate dissociation energy De. The second modification adds replacing the water monomer component of the PES with a spectroscopically accurate one and the third modification produces a hybrid potential that goes smoothly in the asymptotic region to the flexible, Thole-type model potential, version 3 dimer potential (denoted TTM3-F) [G. S. Fanourgakis and S. S. Xantheas, J. Chem. Phys. 128, 074506 (2008)]. The rigorous D0 for these PESs, obtained using diffusion Monte Carlo calculations of the dimer zero-point energy, and an accurate zero-point energy of the monomer, range from 12.5 to 13.2 kJ/mol (2.99-3.15 kcal/mol), with the latter being the suggested benchmark value. For TTM3-F D0 equals 16.1 kJ/mol. Vibrational calculations of monomer fundamental energies using the code MULTIMODE are reported for these PESs and the TTM3-F PES and compared to experiment. A classical molecular dynamics simulation of the infrared spectra of the water dimer and deuterated water dimer at 300 K are also reported using the ab initio dipole moment surface reported previously [X. Huang, B. J. Braams, and J. M. Bowman, J. Phys. Chem. A 110, 445 (2006)].

Shank, Alex; Wang, Yimin; Kaledin, Alexey; Braams, Bastiaan J.; Bowman, Joel M.

2009-04-01

422

Sleep Control for Base Stations Powered by Heterogeneous Energy Sources  

E-print Network

to the power grid, some BSs are purely powered by the renewable energy. BS sleep is introduced not only to save grid power, but also to store renewable energy for future use when the temporal traffic variation does of those BS powered by the renewable energy, and this will lead to network coverage hole and thus severely

423

A theoretical study on the mechanism of electronic to vibrational energy transfer in Hg/3P/ + CO  

NASA Technical Reports Server (NTRS)

The mechanism of electronic-to-vibrational (E-V) energy transfer in Hg(3P) + CO collisions has been studied theoretically. The configuration interaction (CI) method was employed to calculate potential energy surfaces of the collision system. A simplified theoretical model, based on the reaction coordinate concept and the calculated potential energy characteristics, was used to discuss the mechanism of the singlet-triplet transition and the energy disposal in the collision. The results obtained were that: (a) the quenching process processed via a collision complex mechanism; and that (b) the triplet-singlet transition occurs near the collinear geometry. A model classical trajectory calculation gives a product CO vibrational distribution in good agreement with the experimental result.

Kato, S.; Jaffe, R. L.; Komornicki, A.; Morokuma, K.

1983-01-01

424

Energy Storage Applications in Power Systems with Renewable Energy Generation  

NASA Astrophysics Data System (ADS)

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 i