Vibration analysis of cooling system of upgraded PARR-1: (primary pumps)

International Nuclear Information System (INIS)

Ayazuddin, S.K.; Baig, R.; Pervez, S.

1992-12-01

During the conversion and up gradation of PARR-1, major changes were made in the cooling system of the reactor with the addition of new heat exchanger assemblies and cooling tower. It was therefore, planned to perform vibration analysis on the cooling system to check proper installation and investigate any abnormality in the operation. As a first step, vibration measurements was made on the primary pumps PW-P1 and PW-P2. Power spectral density (PSD) or frequency spectrum of the signal produced from an accelerometer placed on the pump motor assembly was analysed to identify faults which are commonly found in rotating and reciprocating machinery such as unbalance, shaft misalignment and bearing instability. The root mean square (RMS) of the signal was compared with the vibration criterion chart to determine the operating condition of the pump motor assembly. The procedure used for the analysis and faults detected in the primary pump-motor system are discussed. 9 figs. (author)

Shock and vibration protection of submerged jet impingement cooling systems: Theory and experiment

International Nuclear Information System (INIS)

Haji Hosseinloo, Ashkan; Tan, Siow Pin; Yap, Fook Fah; Toh, Kok Chuan

2014-01-01

In the recent years, advances in high power density electronics and computing systems have pushed towards more advanced thermal management technologies and higher-capacity cooling systems. Among different types of cooling systems, jet impingement technology has gained attention and been widely used in different industries for its adaptability, cooling uniformity, large heat capacity, and ease of its localization. However, these cooling systems may not function properly in dynamically harsh environment inherent in many applications such as land, sea and air transportation. In this research article, a novel double-chamber jet impingement cooling system is fabricated and its performance is studied in harsh environment. Using the authors' previous studies, isolators with optimum properties are selected to ruggedize the chassis containing the cooling chamber against shock and random vibration. Experiments are conducted on both hard-mounted and isolated chassis and the cooling performance of the system is assessed using the inlet, and impingement surface temperatures of the cooling chamber. The experimental results show the isolation system prevents any failure that otherwise would occur, and also does not compromise the thermal performance of the system. - Highlights: • A novel double-chamber jet impingement cooling system was designed and fabricated. • Comprehensive set of random vibration and shock tests are conducted. • The isolation system proved to protect the cooling system properly against mechanical failure. • Cooling system performance was not significantly affected by the input random vibration and shock

Flow-induced vibration phenomenon in a Mark III TRIGA reactor

Energy Technology Data Exchange (ETDEWEB)

Lee, C K; Whittemore, W L; Kim, B S; Lee, J B; Blevins, R D; Burton, T E [Korea Atomic Energy Research Institute, Seoul (Korea, Republic of); General Atomic Company, San Diego, CA (United States)

1976-07-01

The Mark III TRIGA reactor with hexagonal fuel spacing is capable of operating at 2.0 MW. The Mark III at San Diego operated without core cooling problems or vibration at power levels up to 2.0 MW. All Mark III reactors have operated trouble-free up to 1.0 MW. The Mark III TRIGA in Korea was installed in 1972 and operated many months without trouble at 2.0 MW. During this period core changes including addition of new fuel were made. Eighteen months after startup, a coolant flow-induced vibration was observed for the first time at a power of 1.5 MW. A lengthy series of tests showed that it was not possible to establish a core configuration that permitted vibration-free operation for power levels in the range 1.5 - 2.0 MW. Observations during the tests confirmed that standing waves in the reactor tank water coupled the source within the core to the shield structure and surrounding building. Analysis of the data indicates strongly that the source of the vibration is the creation and collapse of bubbles with the core acting as a resonator. A substantially increased flow of coolant through the upper grid plate is expected to eliminate the vibration phenomenon and permit trouble-free operation at power up to 2.0 MW. In an attempt to seek a remedy, both GAC and KAERI have independently developed designs for upper grid plates. KAERI has constructed and installed an interim version of the standard grid plate which was calculated to provide 25% more coolant flow and mounted high so as to provide less restriction to flow around the upper fittings of the fuel elements. A substantial reduction in vibration was observed. No vibration was observed at any power up to 2.0 MW with cooling water at or below 20 C. A slight vibration at 1.8 MW occurred for higher cooling temperatures. The GAC grid plate design provides not only for increasing the flow area but also for streamlining the flow surfaces on the grid plate and possibly also on the top fittings of the fuel elements. It is

Flow-induced vibration phenomenon in a Mark III TRIGA reactor

International Nuclear Information System (INIS)

Lee, C.K.; Whittemore, W.L.; Kim, B.S.; Lee, J.B.; Blevins, R.D.; Burton, T.E.

1976-01-01

The Mark III TRIGA reactor with hexagonal fuel spacing is capable of operating at 2.0 MW. The Mark III at San Diego operated without core cooling problems or vibration at power levels up to 2.0 MW. All Mark III reactors have operated trouble-free up to 1.0 MW. The Mark III TRIGA in Korea was installed in 1972 and operated many months without trouble at 2.0 MW. During this period core changes including addition of new fuel were made. Eighteen months after startup, a coolant flow-induced vibration was observed for the first time at a power of 1.5 MW. A lengthy series of tests showed that it was not possible to establish a core configuration that permitted vibration-free operation for power levels in the range 1.5 - 2.0 MW. Observations during the tests confirmed that standing waves in the reactor tank water coupled the source within the core to the shield structure and surrounding building. Analysis of the data indicates strongly that the source of the vibration is the creation and collapse of bubbles with the core acting as a resonator. A substantially increased flow of coolant through the upper grid plate is expected to eliminate the vibration phenomenon and permit trouble-free operation at power up to 2.0 MW. In an attempt to seek a remedy, both GAC and KAERI have independently developed designs for upper grid plates. KAERI has constructed and installed an interim version of the standard grid plate which was calculated to provide 25% more coolant flow and mounted high so as to provide less restriction to flow around the upper fittings of the fuel elements. A substantial reduction in vibration was observed. No vibration was observed at any power up to 2.0 MW with cooling water at or below 20 C. A slight vibration at 1.8 MW occurred for higher cooling temperatures. The GAC grid plate design provides not only for increasing the flow area but also for streamlining the flow surfaces on the grid plate and possibly also on the top fittings of the fuel elements. It is

Cooling of molecular ion beams

International Nuclear Information System (INIS)

Wolf, A.; Krohn, S.; Kreckel, H.; Lammich, L.; Lange, M.; Strasser, D.; Grieser, M.; Schwalm, D.; Zajfman, D.

2004-01-01

An overview of the use of stored ion beams and phase space cooling (electron cooling) is given for the field of molecular physics. Emphasis is given to interactions between molecular ions and electrons studied in the electron cooler: dissociative recombination and, for internally excited molecular ions, electron-induced ro-vibrational cooling. Diagnostic methods for the transverse ion beam properties and for the internal excitation of the molecular ions are discussed, and results for phase space cooling and internal (vibrational) cooling are presented for hydrogen molecular ions

Experimental Study on Piezoelectric Energy Harvesting from Vortex-Induced Vibrations and Wake-Induced Vibrations

Directory of Open Access Journals (Sweden)

Min Zhang

2016-01-01

Full Text Available A rigid circular cylinder with two piezoelectric beams attached on has been tested through vortex-induced vibrations (VIV and wake-induced vibrations (WIV by installing a big cylinder fixed upstream, in order to study the influence of the different flow-induced vibrations (FIV types. The VIV test shows that the output voltage increases with the increases of load resistance; an optimal load resistance exists for the maximum output power. The WIV test shows that the vibration of the small cylinder is controlled by the vortex frequency of the large one. There is an optimal gap of the cylinders that can obtain the maximum output voltage and power. For a same energy harvesting device, WIV has higher power generation capacity; then the piezoelectric output characteristics can be effectively improved.

The Results of a Site Repair after a High Vibration Trip of a Secondary Cooling Fan in HANARO

International Nuclear Information System (INIS)

Park, Yong-Chul; Kim, Yang-Gon; Lee, Yong-Sub; Jung, Hawn-Seong; Lim, In-Cheol

2007-01-01

HANARO, an open-tank-in-pool type research reactor of 30 MWth power in Korea, which is different from a power plant reactor, exhausts a heat generated from the reactor core into the atmosphere through a secondary cooling tower instead of an electric power production from the heat. After a cooling tower overhaul, No. 2 cooling fan of the cooling tower was stopped by a high vibration trip while HANARO was operating normally. This paper describes the development of a high vibration trip of the cooling fan and the results of a site repair of the cooling fan

Rotational laser cooling of vibrationally and translationally cold molecular ions

DEFF Research Database (Denmark)

Staanum, Peter; Højbjerre, Klaus; Skyt, Peter Sandegaard

2010-01-01

Stationary molecules in well-defined internal states are of broad interest for physics and chemistry. In physics, this includes metrology 1, 2, 3 , quantum computing 4, 5 and many-body quantum mechanics 6, 7 , whereas in chemistry, state-prepared molecular targets are of interest for uni......-molecular reactions with coherent light fields 8, 9 , for quantum-state-selected bi-molecular reactions 10, 11, 12 and for astrochemistry 12 . Here, we demonstrate rotational ground-state cooling of vibrationally and translationally cold MgH+ ions, using a laser-cooling scheme based on excitation of a single...

Flow induced vibration studies on PFBR control plug components

Energy Technology Data Exchange (ETDEWEB)

Prakash, V., E-mail: prakash@igcar.gov.in [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India); Kumar, P. Anup; Anandaraj, M.; Thirumalai, M.; Anandbabu, C.; Rajan, K.K. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Flow induced vibration studies on Prototype Fast Breeder Reactor control plug model carried out. Black-Right-Pointing-Pointer Velocity similitude was followed for the study. Black-Right-Pointing-Pointer Frequencies and amplitude of vibrations of various control plug components measured. Black-Right-Pointing-Pointer Overall values of vibration are well within permissible limits. - Abstract: The construction of Prototype Fast Breeder Reactor (PFBR), a 500 MWe liquid sodium cooled reactor, is in progress at Kalpakkam in India. Control plug (CP) is located right above the core subassemblies in the hot pool. Control plug is an important component as many of the critical reactor parameters are sensed and controlled by the components housed in the control plug assembly. In PFBR primary circuit, components are basically thin walled, slender shells with diameter to thickness ratio ranging from 100 to 650. These components are prone to flow induced vibrations. The existence of free liquid (sodium) surfaces, which is the source of sloshing phenomenon and the operation of primary sodium pump in the primary pool are other potential sources of vibration of reactor components. Control plug is a hollow cylindrical shell structure and provides passages and support for 12 absorber rod drive mechanisms (ARDM) which consists of 9 control and safety rods and 3 diverse safety rods, 210 thermo wells to measure the sodium temperature at the exit of various fuel subassemblies, three failed fuel localization modules (FFLM) and acoustic detectors. It consists of a core cover plate (CCP), which forms the bottom end, two intermediate supports plate, i.e. lower stay plate (LSP) and upper stay plate (USP) and an outer shell. The CCP is located at a distance of 1.3 m from the core top. With such a gap, there will be long free hanging length of the thermocouple sleeves, Delayed neutron detector (DND) sampling tubes and ARDM shroud tubes and hence they are

Flow-induced vibration -- 1994. PVP-Volume 273

International Nuclear Information System (INIS)

Au-Yang, M.K.; Fujita, K.

1994-01-01

Flow-induced vibration is a subject of practical interest to many engineering disciplines, including the power generation, process, and petrochemical industries. In the nuclear industry, flow-induced vibration reaches a higher level of concern because of safety issues and the huge cost associated with down time and site repair. Not surprisingly, during the last 25 years a tremendous amount of effort has been spent in the study of flow-induced vibration phenomena related to nuclear plant components, notably nuclear steam generator tube banks and nuclear fuel bundles. Yet, in spite of this concentrated effort, the industry is still not free from flow-induced vibration-related problems. This explains why in this volume almost half of the papers address the issue of cross-flow induced vibration in tube bundles, with applications to the nuclear steam generator and nuclear fuel bundles in mind. Unlike 10 or 15 years ago, when flow-induced vibration studies almost always involved experimentation and empirical studies, the advent of high-speed computers has enabled numerical calculation and simulation of this complex phenomenon to take place. Separate abstracts were prepared for 27 papers in this volume

Recycler Electron Cooling Project: Mechanical vibrations in the Pelletron and their effect on the beam

International Nuclear Information System (INIS)

Kazakevich, Grigory M.; Burov, A.; Boffo, C.; Joireman, P.; Saewert, G.; Schmidt, C.W.; Shemyakin, A.; Fermilab

2005-01-01

The Fermilab's Recycler ring will employ an electron cooler to cool stored 8.9 GeV antiprotons [1]. The cooler is based on an electrostatic accelerator, Pelletron [2], working in an energy-recovery regime. A full-scale prototype of the cooler has been assembled and commissioned in a separate building [3]. The main goal of the experiments with the prototype was to demonstrate stable operation with a 3.5 MeV, 0.5 A DC electron beam while preserving a high beam quality in the cooling section. The quality is characterized, first of all, by a spread of electron velocities in the cooling section, which may be significantly affected by mechanical vibration of the Pelletron elements. This paper describes the results of vibration measurements in the Pelletron terminal and correlates them with the beam motion in the cooling section

Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions

DEFF Research Database (Denmark)

Drewsen, Michael

2011-01-01

[7,8,9]. Furthermore, in order to learn more about the chemistry in interstellar clouds, astrochemists can benefit greatly from direct measurements on cold reactions in laboratories [9]. Working with MgH+ molecular ions in a linear Paul trap, we routinely cool their translational degree of freedom...... by sympathetic cooling with Doppler laser cooled Mg+ ions. Giving the time for the molecules to equilibrate internally to the room temperature blackbody radiation, the vibrational degree of freedom will freeze out, leaving only the rotational degree of freedom to be cooled. We report here on the implementation...... results imply that, through this technique, cold molecular-ion experiments can now be carried out at cryogenic temperatures in room-temperature set-ups. References [1] Koelemeij, J. C. J., Roth, B., Wicht, A., Ernsting, I. and Schiller, S., Phys. Rev. Lett. 98, 173002 (2007). [2] Hudson, J. J., Sauer, B...

Development of a perpendicular vibration-induced electrical discharge machining process for fabrication of partially wavy inner structures

Energy Technology Data Exchange (ETDEWEB)

Lee, Ju Chul; Park, Sang Hu; Min, June Kee; Ha, Man Yeong; Shin, Bo Sung [Pusan National University, Busan (Korea, Republic of); Cho, Jong Rae [Korea Maritime University, Busan (Korea, Republic of)

2016-05-15

Heat transfer enhancement is an important issue in energy systems. To improve the efficiency of a cooling channel used inside injection molds, turbine blades, and high-temperature devices, channels with various shapes, such as wavy, elliptical, and twisted, have been studied. A cooling channel with a partially wavy inner structure has shown outstanding cooling performance despite a small increase in friction factor. However, generating a partially wavy inner structure inside a channel through conventional machining processes is not easy. To address this problem, we developed a new process called Perpendicular vibration-induced electrical discharge machining (PV-EDM). A specific electrode and one- and random-directional vibrating devices controlled by a pneumatic load were designed for the PV-EDM process. Experimental results showed that local shaping on the inner wall of a channel is possible, which confirmed the possibility of application of this process to actual industrial problems.

Development of an Anti-Vibration Controller for Magnetic Bearing Cooling Systems, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This proposal outlines a program to develop a vibration-free reverse-Brayton cycle cooling system using specially-tuned magnetic bearings. Such a system is critical...

Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions

DEFF Research Database (Denmark)

Drewsen, Michael

2011-01-01

an excellent alternative to atomic qubits in the realization of a practical ion trap based quantum computer due to favourable internal state decoherence rates. In chemistry, state prepared molecular targets are an ideal starting point for uni-molecular reactions, including coherent control...... of photofragmentation through the application of various laser sources [5,6]. In cold bi-molecular reactions, where the effect of even tiny potential barriers becomes significant, experiments with state prepared molecules can yield important information on the details of the potential curves of the molecular complexes...... by sympathetic cooling with Doppler laser cooled Mg+ ions. Giving the time for the molecules to equilibrate internally to the room temperature blackbody radiation, the vibrational degree of freedom will freeze out, leaving only the rotational degree of freedom to be cooled. We report here on the implementation...

Assessment of flow induced vibration in a sodium-sodium heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Prakash, V. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)], E-mail: prakash@igcar.gov.in; Thirumalai, M.; Prabhakar, R.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)

2009-01-15

The 500 MWe Prototype Fast Breeder Reactor (PFBR) is under construction at Kalpakkam. It is a liquid metal sodium cooled pool type fast reactor with all primary components located inside a sodium pool. The heat produced due to fission in the core is transported by primary sodium to the secondary sodium in a sodium to sodium Intermediate Heat Exchanger (IHX), which in turn is transferred to water in the steam generator. PFBR IHX is a shell and tube type heat exchanger with primary sodium on shell side and secondary sodium in the tube side. Since IHX is one of the critical components placed inside the radioactive primary sodium, trouble-free operation of the IHX is very much essential for power plant availability. To validate the design and the adequacy of the support system provided for the IHX, flow induced vibration (FIV) experiments were carried out in a water test loop on a 60 deg. sector model. This paper discusses the flow induced vibration measurements carried out in 60 deg. sector model of IHX, the modeling criteria, the results and conclusion.

Combination of Ultrasonic Vibration and Cryogenic Cooling for Cutting Performance Improvement of Inconel 718 Turning

Science.gov (United States)

Lin, S. Y.; Chung, C. T.; Cheng, Y. Y.

2011-01-01

The main objective of this study is to develop a thermo-elastic-plastic coupling model, based on a combination skill of ultrasonically assisted cutting and cryogenic cooling, under large deformation for Inconel 718 alloy machining process. The improvement extent on cutting performance and tool life promotion may be examined from this investigation. The critical value of the strain energy density of the workpiece will be utilized as the chip separation and the discontinuous chip segmentation criteria. The forced convection cooling and a hydrodynamic lubrication model will be considered and formulated in the model. Finite element method will be applied to create a complete numerical solution for this ultrasonic vibration cutting model. During the analysis, the cutting tool is incrementally advanced forward with superimposed ultrasonic vibration in a back and forth step-by-step manner, from an incipient stage of tool-workpiece engagement to a steady state of chip formation, a whole simulation of orthogonal cutting process under plane strain deformation is thus undertaken. High shear strength induces a fluctuation phenomenon of shear angle, high shear strain rate, variation of chip types and chip morphology, tool-chip contact length variation, the temperature distributions within the workpiece, chip and tool, periodic fluctuation in cutting forces can be determined from the developed model. A complete comparison of machining characteristics between some different combinations of ultrasonically assisted cutting and cryogenic cooling with conventional cutting operation can be acquired. Finally, the high-speed turning experiment for Inconel 718 alloy will be taken in the laboratory to validate the accuracy of the model, and the progressive flank wear, crater wear, notching and chipping of the tool edge can also be measured in the experiments.

Parametric analysis of protective grid flow induced vibration

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jooyoung; Eom, Kyongbo; Jeon, Sangyoun; Suh, Jungmin [KEPCO NF Co., Daejeon (Korea, Republic of)

2012-10-15

Protective grid (P-grid) flow-induced vibration in a nuclear power reactor is one of the critical factors for the mechanical integrity of a nuclear fuel. The P-grid is located at the lower most position above the bottom nozzle of the nuclear fuel as shown in Fig. 1, and it is required for not only filtering debris, but also supporting fuel rods. On the other hand, P-grid working conditions installed in a nuclear fuel in a reactor are severe in terms of flow speed, temperature and pressure. Considering such a severe condition of P-grid's functional performance in working environment, excessive vibration could be developed. Furthermore, if the P-grid is exposed to high levels of excessive vibration over a long period of time, fatigue failure could be unavoidable. Therefore, it is important to reduce excessive vibration while maintaining P-grid's own functional performance. KEPCO Nuclear Fuel has developed a test facility - Investigation Flow-induced Vibration (INFINIT) - to study flow-induced vibration caused by flowing coolant at various flow rates. To investigate specific relationships between configuration of P-grid and flow-induced vibration characteristics, several types of the P-grids were tested in INFINIT facility. And, based on the test results through parametric studies, the flow-induced vibration characteristics could be analyzed, and critical design parameters were found.

Flow-Induced Vibration of Circular Cylindrical Structures

Energy Technology Data Exchange (ETDEWEB)

Chen, Shoei-Sheng [Argonne National Lab. (ANL), Argonne, IL (United States). Components Technology Division

1985-06-01

Flow-induced vibration is a term to denote those phenomena associated with the response of structures placed in or conveying fluid flow. More specifically, the terra covers those cases in which an interaction develops between fluid-dynamic forces and the inertia, damping or elastic forces in the structures. The study of these phenomena draws on three disciplines: (1) structural mechanics, (2) mechanical vibration, and (3) fluid dynamics. The vibration of circular cylinders subject to flow has been known to man since ancient times; the vibration of a wire at its natural frequency in response to vortex shedding was known in ancient Greece as aeolian tones. But systematic studies of the problem were not made until a century ago when Strouhal established the relationship between vortex shedding frequency and flow velocity for a given cylinder diameter. The early research in this area has beer summarized by Zdravkovich (1985) and Goldstein (1965). Flow-induced structural vibration has been experienced in numerous fields, including the aerospace industry, power generation/transmission (turbine blades, heat exchanger tubes, nuclear reactor components), civil engineering (bridges, building, smoke stacks), and undersea technology. The problems have usually been encountered or created accidentally through improper design. In most cases, a structural or mechanical component, designed to meet specific objectives, develops problems when the undesired effects of flow field have not been accounted for in the design. When a flow-induced vibration problem is noted in the design stage, the engineer has different options to eliminate the detrimental vibration. Unfortunately, in many situations, the problems occur after the components are already in operation; the "fix" usually is very costly. Flow-induced vibration comprises complex and diverse phenomena; subcritical vibration of nuclear fuel assemblies, galloping of transmission lines, flutter of pipes conveying fluid, and whirling

Study on flow-induced vibration of large-diameter pipings in a sodium-cooled fast reactor. Influence of elbow curvature on velocity fluctuation field

International Nuclear Information System (INIS)

Ono, Ayako; Kimura, Nobuyuki; Kamide, Hideki; Tobita, Akira

2010-02-01

The main cooling system of Japan Sodium-cooled Fast Reactor (JSFR) consists of two loops to reduce the plant construction cost. In the design of JSFR, sodium coolant velocity is beyond 9m/s in the primary hot leg pipe with large-diameter (1.3m). The maximum Reynolds number in the piping reaches 4.2x10 7 . The hot leg pipe having a 90 degree elbow with curvature ratio of r/D=1.0, so-called 'short elbow', which enables a compact reactor vessel. In sodium cooled fast reactors, the system pressure is so low that thickness of pipings in the cooling system is thinner than that in LWRs. Under such a system condition in the cooling system, the flow-induced vibration (FIV) is concerned at the short elbow. The evaluation of the structural integrity of pipings in JSFR should be conducted based on a mechanistic approach of FIV at the elbow. It is significant to obtain the knowledge of the fluctuation intensity and spectra of velocity and pressure fluctuations in order to grasp the mechanism of the FIV. In this study, water experiments were conducted. Two types of 1/8 scaled elbows with different curvature ratio, r/D=1.0, 1.5, were used to investigate the influence of curvature on velocity fluctuation at the elbow. The velocity fields in the elbows were measured using a high speed PIV method. Unsteady behavior of secondary flow at the elbow outlet and separation flow at the inner wall of elbow were observed in the two types of elbows. It was found that the growth of secondary flow correlated with the flow fluctuation near the inside wall of the elbow. (author)

Non-equilibrium effects evidenced by vibrational spectra during the coil-to-globule transition in poly(N-isopropylacrylamide) subjected to an ultrafast heating-cooling cycle.

Science.gov (United States)

Deshmukh, Sanket A; Kamath, Ganesh; Suthar, Kamlesh J; Mancini, Derrick C; Sankaranarayanan, Subramanian K R S

2014-03-14

Molecular dynamics simulations in conjunction with finite element calculations are used to explore the conformational dynamics of a thermo-sensitive oligomer, namely poly(N-isopropylacrylamide) (PNIPAM), subjected to an ultra-fast heating-cooling cycle. Finite element (FE) calculations were used to predict the temperature profile resulting from laser-induced heating of the polymer-aqueous system. The heating rate (∼0.6 K ps(-1)) deduced from FE calculations was used to heat an aqueous solution of PNIPAM consisting of 30 monomeric units (30-mer) from 285 K to 315 K. Non-equilibrium effects arising from the ultra-fast heating-cooling cycle results in a hysteresis during the coil-to-globule transition. The corresponding atomic scale conformations were characterized by monitoring the changes in the vibrational spectra, which provided a reliable metric to study the coil-to-globule transition in PNIPAM and vice-versa across the LCST. The vibrational spectra of bonds involving atoms from the oligomer backbone and the various side-groups (amide I, amide II, and the isopropyl group of PNIPAM) of the oligomers were analyzed to study the conformational changes in the oligomer corresponding to the observed hysteresis. The differences in the vibrational spectra calculated at various temperatures during heating and cooling cycles were used to understand the coil-to-globule and globule-to-coil transitions in the PNIPAM oligomer and identify the changes in the relative interactions between various atoms in the backbone and in the side groups of the oligomer with water. The shifts in the computed vibrational spectral peaks and the changes in the intensity of peaks for the different regions of PNIPAM, seen across the LCST during the heating cycle, are in good agreement with previous experimental studies. The changes in the radius of gyration (Rg) and vibrational spectra for amide I and amide II regions of PNIPAM suggest a clear coil-to-globule transition at ∼301 K during the

Vibration-Induced Climbing of Drops

Science.gov (United States)

Brunet, P.; Eggers, J.; Deegan, R. D.

2007-10-01

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.

Scale modeling flow-induced vibrations of reactor components

International Nuclear Information System (INIS)

Mulcahy, T.M.

1982-06-01

Similitude relationships currently employed in the design of flow-induced vibration scale-model tests of nuclear reactor components are reviewed. Emphasis is given to understanding the origins of the similitude parameters as a basis for discussion of the inevitable distortions which occur in design verification testing of entire reactor systems and in feature testing of individual component designs for the existence of detrimental flow-induced vibration mechanisms. Distortions of similitude parameters made in current test practice are enumerated and selected example tests are described. Also, limitations in the use of specific distortions in model designs are evaluated based on the current understanding of flow-induced vibration mechanisms and structural response

Dynamic Characteristics of Flow Induced Vibration in a Rotor-Seal System

Directory of Open Access Journals (Sweden)

Nan Zhang

2011-01-01

Full Text Available Flow induced vibration is an important factor affecting the performance of the rotor-seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the fluid force, which is induced by the interaction between the unstable fluid flow in the seal and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear models. Various nonlinear phenomena of flow induced vibration in the rotor-seal system, such as synchronization phenomenon and amplitude mutation, are reproduced.

Simulation of fuel rods vibration in power reactors by vibration of tape coated with cadmium

International Nuclear Information System (INIS)

Holland, L.

1982-01-01

The circulation of cooling water in light water power reactor makes a vibration in internal components. The monitoring of those vibrations is necessary aiming to the safety use of reactors. Aiming at study those vibrations a neutron absorber, type vibratory tape was introduced in the core of a research reactor type Pulstar, operating at 80 W of power. The induced power variations were measured with an ionization chamber put besides the reactor core. The detector signal was recorded and analysed in a PDP-11 computer. The analysis of the results show that the power density of the detector signal, and thus, the power reactor, increase in the O-25 Hz range with an increase in the pulse height vibration. (E.G.) [pt

Alleviation of Buffet-Induced Vibration Using Piezoelectric Actuators

National Research Council Canada - National Science Library

Morgenstern, Shawn D

2006-01-01

.... The objective of this research was to determine the most critical natural modes of vibration for the F-16 ventral fin and design piezoelectric actuators capable of reducing buffet-induced ventral fin vibration...

Structural Design Optimization On Thermally Induced Vibration

International Nuclear Information System (INIS)

Gu, Yuanxian; Chen, Biaosong; Zhang, Hongwu; Zhao, Guozhong

2002-01-01

The numerical method of design optimization for structural thermally induced vibration is originally studied in this paper and implemented in application software JIFEX. The direct and adjoint methods of sensitivity analysis for thermal induced vibration coupled with both linear and nonlinear transient heat conduction is firstly proposed. Based on the finite element method, the structural linear dynamics is treated simultaneously with coupled linear and nonlinear transient heat structural linear dynamics is treated simultaneously with coupled linear and nonlinear transient heat conduction. In the thermal analysis model, the nonlinear heat conduction considered is result from the radiation and temperature-dependent materials. The sensitivity analysis of transient linear and nonlinear heat conduction is performed with the precise time integration method. And then, the sensitivity analysis of structural transient dynamics is performed by the Newmark method. Both the direct method and the adjoint method are employed to derive the sensitivity equations of thermal vibration, and there are two adjoint vectors of structure and heat conduction respectively. The coupling effect of heat conduction on thermal vibration in the sensitivity analysis is particularly investigated. With coupling sensitivity analysis, the optimization model is constructed and solved by the sequential linear programming or sequential quadratic programming algorithm. The methods proposed have been implemented in the application software JIFEX of structural design optimization, and numerical examples are given to illustrate the methods and usage of structural design optimization on thermally induced vibration

Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

Directory of Open Access Journals (Sweden)

Gu Wenbin

2015-01-01

Full Text Available Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater drilling blasting was measured in a field experiment. It shows that the water bottom vibration monitor could collect vibration signals quite effectively in underwater environments. The followed signal analysis shows that the characteristics of water bottom vibration and land ground vibration induced by the same underwater drilling blasting are quite different due to the different geological environments. The amplitude and frequency band of water bottom vibration both exceed those of land ground vibration. Water bottom vibration is mainly in low-frequency band that induced by blasting impact directly acts on rock. Besides the low-frequency component, land vibration contains another higher frequency band component that induced by followed water hammer wave acts on bank slope.

Prediction of induced vibrations in stall

Energy Technology Data Exchange (ETDEWEB)

Thirstrup Petersen, J; Thomsen, K; Aagaard Madsen, H [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

1999-03-01

The main results from recent research in stall induced vibrations are presented. The focus is on the edgewise blade vibrations, which during the last decade have turned out to be a potential threat against the stable operation of stall regulated wind turbines and a fact, which must be dealt with by the designer. The basic physical explanation for the phenomenon and examples of design precaution, which can be taken, are presented. (au)

Intermediate heat exchanger tube vibration induced by cross and parallel mixed flow

International Nuclear Information System (INIS)

Kawamura, Koji

1986-01-01

The characteristics of pool type LMFBR intermediate heat exchanger (IHX) tube vibrations induced by cross and parallel mixed flow were basically investigated. Secondary coolant in IHX tube bundle is mixed flow of parallel jit flow along the tube axis through flow holes in baffle plates and cross flow. By changing these two flow rate, flow distributions vary in the tube bundle. Mixed flow also induces vibrations which cause fretting wear and fatigue of tube. It is therefore very important to evaluate the tube vibration characteristics for estimating the tube integrity. The results show that the relationships between tube vibrations and flow distributions in the tube bundle were cleared, and mixed flow induced tube vibration could be evaluated on the base of the characteristics of both parallel and cross flow induced vibration. From these investigations it could be concluded that the characteristics of tube vibration for various flow distributions can be systematically evaluated. (author)

Specialists meeting on LMFBR flow induced vibrations. Summary report

International Nuclear Information System (INIS)

1977-12-01

A Specialists' Meeting on LMFBR Flow-Induced Vibrations was held at ANL in the United States which was sponsored by the International Atomic Energy Agency (IAEA) on the recommendations of the International Working Group on Fast Reactors (IWGFR). It was attended by participants from France, the Federal Republic of Germany, Italy, Japan, Netherlands, the United Kingdom, the Union of Soviet Socialist Republics, the United States and the IAEA. The purpose of the meeting was to provide, for the first time, a common forum for the exchange of information on flow-induced vibration programs of the member countries. As this was a first meeting, information was sought in the broad areas of: 1. Design Criteria and Problem Areas in LMFBR Design; 2. Current Design Procedures; and 3. Ongoing Research. A session was devoted to each of the above topics wherein papers were presented and discussed followed by open discussions on the session topic. The objective of the open discussions was to identify, from a review of specific reactor designs, (a) flow induced vibration problem areas (expected and observed) and their potential for occurrence; (b) failure modes and associated design criteria; (c) specific components that are susceptible to flow induced vibration; and (d) probable excitation mechanisms. It was aimed to assess the current state-of-the-art in designing to avoid flow induced vibration with consideration of licensing requirements; to evaluate existing methods of analysis, testing, and surveillance, along with their limitations and to identify areas requiring research and review ongoing research programmes relative to these research needs

Specialists meeting on LMFBR flow induced vibrations. Summary report

Energy Technology Data Exchange (ETDEWEB)

NONE

1977-12-01

A Specialists' Meeting on LMFBR Flow-Induced Vibrations was held at ANL in the United States which was sponsored by the International Atomic Energy Agency (IAEA) on the recommendations of the International Working Group on Fast Reactors (IWGFR). It was attended by participants from France, the Federal Republic of Germany, Italy, Japan, Netherlands, the United Kingdom, the Union of Soviet Socialist Republics, the United States and the IAEA. The purpose of the meeting was to provide, for the first time, a common forum for the exchange of information on flow-induced vibration programs of the member countries. As this was a first meeting, information was sought in the broad areas of: 1. Design Criteria and Problem Areas in LMFBR Design; 2. Current Design Procedures; and 3. Ongoing Research. A session was devoted to each of the above topics wherein papers were presented and discussed followed by open discussions on the session topic. The objective of the open discussions was to identify, from a review of specific reactor designs, (a) flow induced vibration problem areas (expected and observed) and their potential for occurrence; (b) failure modes and associated design criteria; (c) specific components that are susceptible to flow induced vibration; and (d) probable excitation mechanisms. It was aimed to assess the current state-of-the-art in designing to avoid flow induced vibration with consideration of licensing requirements; to evaluate existing methods of analysis, testing, and surveillance, along with their limitations and to identify areas requiring research and review ongoing research programmes relative to these research needs.

Vibration-induced particle formation during yogurt fermentation - Industrial vibration measurements and development of an experimental setup.

Science.gov (United States)

Körzendörfer, Adrian; Temme, Philipp; Nöbel, Stefan; Schlücker, Eberhard; Hinrichs, Jörg

2016-07-01

The aim of the study was to investigate the effects of vibrations during yogurt fermentation. Machinery such as pumps and switching valves generate vibrations that may disturb the gelation by inducing large particles. Oscillation measurements on an industrial yogurt production line showed that oscillations are transferred from pumps right up to the fermentation tanks. An experimental setup (20L) was developed to study the effect of vibrations systematically. The fermenters were decoupled with air springs to enable reference fermentations under idle conditions. A vibration exciter was used to stimulate the fermenters. Frequency sweeps (25-1005Hz, periodic time 10s) for 20min from pH5.4 induced large particles. The number of visible particles was significantly increased from 35±4 (reference) to 89±9 particles per 100g yogurt. Rheological parameters of the stirred yogurt samples were not influenced by vibrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flow-induced vibration in LMFBR steam generators: a state-of-the-art review

International Nuclear Information System (INIS)

Shin, Y.S.; Wambsganss, M.W.

1975-05-01

This state-of-the-art review identifies and discusses existing methods of flow-induced vibration analysis applicable to steam generators, their limitations, and base-technology needs. Also included are discussions of five different LMFBR steam-generator configurations and important design considerations, failure experiences, possible flow-induced excitation mechanisms, vibration testing, and available methods of vibration analysis. The objectives are to aid LMFBR steam-generator designers in making the best possible evaluation of potential vibration in steam-generator internals, and to provide the basis for development of design guidelines to avoid detrimental flow-induced vibration

Mechanisms mediating vibration-induced chronic musculoskeletal pain analyzed in the rat.

Science.gov (United States)

Dina, Olayinka A; Joseph, Elizabeth K; Levine, Jon D; Green, Paul G

2010-04-01

While occupational exposure to vibration is a common cause of acute and chronic musculoskeletal pain, eliminating exposure produces limited symptomatic improvement, and reexposure precipitates rapid recurrence or exacerbation. To evaluate mechanisms underlying these pain syndromes, we have developed a model in the rat, in which exposure to vibration (60-80Hz) induces, in skeletal muscle, both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia to a proinflammatory cytokine or reexposure to vibration. Exposure of a hind limb to vibration-produced mechanical hyperalgesia measured in the gastrocnemius muscle of the exposed hind limb, which persisted for approximately 2 weeks. When nociceptive thresholds had returned to baseline, exposure to a proinflammatory cytokine or reexposure to vibration produced markedly prolonged hyperalgesia. The chronic prolongation of vibration- and cytokine-hyperalgesia was prevented by spinal intrathecal injection of oligodeoxynucleotide (ODN) antisense to protein kinase Cepsilon, a second messenger in nociceptors implicated in the induction and maintenance of chronic pain. Vibration-induced hyperalgesia was inhibited by spinal intrathecal administration of ODN antisense to receptors for the type-1 tumor necrosis factor-alpha (TNFalpha) receptor. Finally, in TNFalpha-pretreated muscle, subsequent vibration-induced hyperalgesia was markedly prolonged. These studies establish a model of vibration-induced acute and chronic musculoskeletal pain, and identify the proinflammatory cytokine TNFalpha and the second messenger protein kinase Cepsilon as targets against which therapies might be directed to prevent and/or treat this common and very debilitating chronic pain syndrome. Copyright 2010 American Pain Society. All rights reserved.

FLOW-INDUCED VIBRATION IN PIPES: CHALLENGESS AND SOLUTIONS - A REVIEW

Directory of Open Access Journals (Sweden)

M. SIBA

2016-03-01

Full Text Available The Flow-induced vibration has recently been the topic of experimental, numerical, and theoretical studies. It was intended to implement better applications for controlling the flow using orifice technique. Having the flow under control, the orifice becomes an instrument for measuring the flow. The flow of all fluid such as water, oil, gas and vapours through an orifice was tested and mathematical models were developed adequately. The basic theme for these enormous studies was the need for the very accurate flow measurements through orifices. All experimental, theoretical, numerical, and analytical studies have agreed that there is more than one avenue to develop, modify, and enhance such measurements. However, one factor that affects the flow measurements is the vibration which was not treated as required until the mid-20th century due to enormous discoveries that damages could be rooted to vibration. Researchers have studied vibration and then proposed mathematical models in conjunction with the pressure and velocity measurements of the flowing fluids and then the effect of the vibration, induced or not induced, has been under continuous investigation. This paper is an attempt to review the previous studies regarding understanding the nature of the vibration and the possible effects of vibration on the flow and on the piping structure in order to limit the damage caused by the vibration. This study shows that the need for more experimental studies and more comprehensive analytical approaches are, in particular, very essential to develop better results.

Flow-induced vibration and fretting-wear damage in a moisture separator reheater

International Nuclear Information System (INIS)

Pettigrew, M.J.; Taylor, C.E.; Fisher, N.J.

1996-01-01

Tube failures due to excessive flow-induced vibration were experienced in the tube bundles of moisture separator reheaters in a BWR nuclear station. This paper presents the results of a root cause analysis and covers recommendations for continued operation and for replacement tube bundles. The following tasks are discussed: tube failure analysis; flow velocity distribution calculations; flow-induced vibration analysis with particular emphasis on finned-tubes; fretting-wear testing of a tube and tube-support material combination under simulated operating conditions; field measurements of flow-induced vibration; and development of vibration specifications for replacement tube bundles. The effect of transient operating conditions and of other operational changes such as tube fouling were considered in the analysis. This paper outlines a typical field problem and illustrates the application of flow-induced vibration technology for the solution of a practical problem

Flow induced vibrations in liquid metal fast breeder reactors

International Nuclear Information System (INIS)

1989-01-01

Flow induced vibrations are well known phenomena in industry. Engineers have to estimate their destructive effects on structures. In the nuclear industry, flow induced vibrations are assessed early in the design process, and the results are incorporated in the design procedures. In many cases, model testing is used to supplement the design process to ensure that detrimental behaviour due to flow induced vibrations will not occur in the component in question. While these procedures attempt to minimize the probability of adverse performance of the various components, there is a problem in the extrapolation of analytical design techniques and/or model testing to actual plant operation. Therefore, sodium tests or vibrational measurements of components in the reactor system are used to provide additional assurance. This report is a general survey of experimental and calculational methods in this area of structural mechanics. The report is addressed to specialists and institutions in industrialized and developing countries who are responsible for the design and operation of liquid metal fast breeder reactors. 92 refs, 90 figs, 8 tabs

Induced draught circular cooling tower

International Nuclear Information System (INIS)

Blanquet, J.C.

1980-01-01

Induced draught atmospheric cooling towers are described, to wit those in which the circulation is by power fans. This technique with fans grouped together in the centre enables a single tower to be used and provides an excellent integration of the steam wreath into the atmosphere. This type of cooling tower has been chosen for fitting out two 900 MW units of the Chinon power station in France [fr

Physical model study of neutron noise induced by vibration of reactor internals

International Nuclear Information System (INIS)

Liu Jinhui; Gu Fangyu

1999-01-01

The author presents a physical model of neutron noise induced by reactor internals vibration in frequency domain. Based on system control theory, the reactor dynamic equations are coupled with random vibration equation, and non-linear terms are also taken into accounted while treating the random vibration. Experiments carried out on a zero-power reactor show that the model can be used to describe dynamic character of neutron noise induced by internals' vibration. The model establishes a method to help to determine internals'vibration features, and to diagnosis anomalies through neutron noise

Vibration Monitoring Using Fiber Optic Sensors in a Lead-Bismuth Eutectic Cooled Nuclear Fuel Assembly

Directory of Open Access Journals (Sweden)

Ben De Pauw

2016-04-01

Full Text Available Excessive fuel assembly vibrations in nuclear reactor cores should be avoided in order not to compromise the lifetime of the assembly and in order to prevent the occurrence of safety hazards. This issue is particularly relevant to new reactor designs that use liquid metal coolants, such as, for example, a molten lead-bismuth eutectic. The flow of molten heavy metal around and through the fuel assembly may cause the latter to vibrate and hence suffer degradation as a result of, for example, fretting wear or mechanical fatigue. In this paper, we demonstrate the use of optical fiber sensors to measure the fuel assembly vibration in a lead-bismuth eutectic cooled installation which can be used as input to assess vibration-related safety hazards. We show that the vibration characteristics of the fuel pins in the fuel assembly can be experimentally determined with minimal intrusiveness and with high precision owing to the small dimensions and properties of the sensors. In particular, we were able to record local strain level differences of about 0.2 μϵ allowing us to reliably estimate the vibration amplitudes and modal parameters of the fuel assembly based on optical fiber sensor readings during different stages of the operation of the facility, including the onset of the coolant circulation and steady-state operation.

Friction interface mechanics and self-induced vibrations

OpenAIRE

Wernitz, Boris Alexander

2013-01-01

Vibrations in braking systems have been studied since the beginning of the last century and despite several insights, still many phenomena, particularly in the area of friction induced vibrations, are not fully understood. The objective of the actual study was the identification of the complex dynamics in the friction interface of a dry friction brake system. In this context, particular consideration was given to the generation of instabilities and brake squeal. In work presently being ...

Flow induced vibration in shell and tube heat exchangers

International Nuclear Information System (INIS)

Soper, B.M.H.

1981-01-01

Assessing heat exchanger designs, from the standpoint of flow induced vibration, is becoming increasingly important as shell side flow velocities are increased in a quest for better thermal performance. This paper reviews the state of the art concerning the main sources of vibration excitation, i.e. vortex shedding resonance, turbulent buffeting, fluidelastic instability and acoustic resonance, as well as the structural dynamics of the tubes. It is concluded that there are many areas which require further investigation but there are sufficient data available at present to design, with reasonable confidence, units that will be free from flow induced vibration. Topics which are considered to be key areas for further work are listed

Magnetically induced rotor vibration in dual-stator permanent magnet motors

Science.gov (United States)

Xie, Bang; Wang, Shiyu; Wang, Yaoyao; Zhao, Zhifu; Xiu, Jie

2015-07-01

Magnetically induced vibration is a major concern in permanent magnet (PM) motors, which is especially true for dual-stator motors. This work develops a two-dimensional model of the rotor by using energy method, and employs this model to examine the rigid- and elastic-body vibrations induced by the inner stator tooth passage force and that by the outer. The analytical results imply that there exist three typical vibration modes. Their presence or absence depends on the combination of magnet/slot, force's frequency and amplitude, the relative position between two stators, and other structural parameters. The combination and relative position affect these modes via altering the force phase. The predicted results are verified by magnetic force wave analysis by finite element method (FEM) and comparison with the existing results. Potential directions are also given with the anticipation of bringing forth more interesting and useful findings. As an engineering application, the magnetically induced vibration can be first reduced via the combination and then a suitable relative position.

Differences in Train-induced Vibration between Hard Soil and Soft Soil

Science.gov (United States)

Noyori, M.; Yokoyama, H.

2017-12-01

Vibration and noise caused by running trains sometimes raises environmental issues. Train-induced vibration is caused by moving static and dynamic axle loads. To reduce the vibration, it is important to clarify the conditions under which the train-induced vibration increases. In this study, we clarified the differences in train-induced vibration between on hard soil and on soft soil using a numerical simulation method. The numerical simulation method we used is a combination of two analysis. The one is a coupled vibration analysis model of a running train, a track and a supporting structure. In the analysis, the excitation force of the viaduct slabs generated by a running train is computed. The other analysis is a three-dimensional vibration analysis model of a supporting structure and the ground into which the excitation force computed by the former analysis is input. As a result of the numerical simulation, the ground vibration in the area not more than 25m from the center of the viaduct is larger under the soft soil condition than that under the hard soil condition in almost all frequency ranges. On the other hand, the ground vibration of 40 and 50Hz at a point 50m from the center of the viaduct under the hard soil condition is larger than that under the soft soil condition. These are consistent with the result of the two-dimensional FEM based on a ground model alone. Thus, we concluded that these results are obtained from not the effects of the running train but the vibration characteristics of the ground.

Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

OpenAIRE

Wenbin, Gu; Jianghai, Chen; Zhenxiong, Wang; Zhihua, Wang; Jianqing, Liu; Ming, Lu

2015-01-01

Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater ...

Vibration-Induced Kinesthetic Illusions and Corticospinal Excitability Changes.

Science.gov (United States)

Mancheva, Kapka; Rollnik, Jens D; Wolf, Werner; Dengler, Reinhard; Kossev, Andon

2017-01-01

The authors' aim was to investigate the changes of corticospinal excitability during kinesthetic illusions induced by tendon vibration. Motor-evoked potentials in response to transcranial magnetic stimulation were recorded from the vibrated flexor carpi radialis and its antagonist, extensor carpi radialis. The illusions were evoked under vision conditions without feedback for the position of the wrist (open or closed eyes). In these two conditions motor-evoked potential changes during vibration in the antagonist were not identical. This discrepancy may be a result of 2 simultaneously acting, different and opposite influences and the balance between them depends on visual conditions. Thus, the illusion was accompanied by the facilitation of corticospinal excitability in both vibrated muscle and its antagonist.

Energy harvesting by means of flow-induced vibrations on aerospace vehicles

Science.gov (United States)

Li, Daochun; Wu, Yining; Da Ronch, Andrea; Xiang, Jinwu

2016-10-01

This paper reviews the design, implementation, and demonstration of energy harvesting devices that exploit flow-induced vibrations as the main source of energy. Starting with a presentation of various concepts of energy harvesters that are designed to benefit from a general class of flow-induced vibrations, specific attention is then given at those technologies that may offer, today or in the near future, a potential benefit to extend the operational capabilities and to monitor critical parameters of unmanned aerial vehicles. Various phenomena characterized by flow-induced vibrations are discussed, including limit cycle oscillations of plates and wing sections, vortex-induced and galloping oscillations of bluff bodies, vortex-induced vibrations of downstream structures, and atmospheric turbulence and gusts. It was found that linear or linearized modeling approaches are commonly employed to support the design phase of energy harvesters. As a result, highly nonlinear and coupled phenomena that characterize flow-induced vibrations are neglected in the design process. The Authors encourage a shift in the current design paradigm: considering coupled nonlinear phenomena, and adequate modeling tools to support their analysis, from a design limitation to a design opportunity. Special emphasis is placed on identifying designs and implementations applicable to aircraft configurations. Application fields of flow-induced vibrations-based energy harvesters are discussed including power supply for wireless sensor networks and simultaneous energy harvest and control. A large body of work on energy harvesters is included in this review journal. Whereas most of the references claim direct applications to unmanned aerial vehicles, it is apparent that, in most of the cases presented, the working principles and characteristics of the energy harvesters are incompatible with any aerospace applications. Finally, the challenges that hold back the integration of energy harvesting

Heat exchanger vibrations - a case study (Paper No. 5.12)

International Nuclear Information System (INIS)

Khilnaney, V.K.

1992-01-01

The satisfactory performance of heat exchangers is crucial to the reliability of the plant. Thorough vibration analysis is essential at design stage to avoid failures at the time of operation. Detailed vibration analysis techniques were not available at the time of designing these exchangers and the exchangers were designed as per general guidelines and prevalent good engineering practices. The designs were not checked especially from the point of view of their proneness to excessive flow induced vibration. The present paper gives a study of revamping of cooling water heat exchanger at Heavy Water Plant, Kota. (author)

Flow-induced vibration of helical coil compression springs

International Nuclear Information System (INIS)

Stokes, F.E.; King, R.A.

1983-01-01

Helical coil compression springs are used in some nuclear fuel assembly designs to maintain holddown and to accommodate thermal expansion. In the reactor environment, the springs are exposed to flowing water, elevated temperatures and pressures, and irradiation. Flow parallel to the longitudinal axis of the spring may excite the spring coils and cause vibration. The purpose of this investigation was to determine the flow-induced vibration (FIV) response characteristics of the helical coil compression springs. Experimental tests indicate that a helical coil spring responds like a single circular cylinder in cross-flow. Two FIV excitation mechanisms control spring vibration. Namely: 1) Turbulent Buffeting causes small amplitude vibration which increases as a function of velocity squared. 2) Vortex Shedding causes large amplitude vibration when the spring natural frequency and Strouhal frequency coincide. Several methods can be used to reduce or to prevent vortex shedding large amplitude vibrations. One method is compressing the spring to a coil pitch-to-diameter ratio of 2 thereby suppressing the vibration amplitude. Another involves modifying the spring geometry to alter its stiffness and frequency characteristics. These changes result in separation of the natural and Strouhal frequencies. With an understanding of how springs respond in the flowing water environment, the spring physical parameters can be designed to avoid large amplitude vibration. (orig.)

Vibration induced sliding: theory and experiment for a beam with a spring-loaded mass

DEFF Research Database (Denmark)

Miranda, Erik; Thomsen, Jon Juel

1998-01-01

The study sets up a simple model for predicting vibration induced sliding of mass, and provides quantitative experimental evidence for the validity of the model. The results lend confidence to recent theoretical developments on using vibration induced sliding for passive vibration damping, and co...

Fatigue failure by in-line flow-induced vibration and fatigue life evaluation

International Nuclear Information System (INIS)

Odahara, Satoru; Murakami, Yukitaka; Inoue, Masahiro; Sueoka, Atsuo

2004-01-01

The phenomenon of fatigue failure by the In-line flow-induced vibration was studied. A newly water-flow-induced vibration system was made and used to reproduce fatigue failure by flow-induced vibration. A medium carbon steel specimen was fixed to the experimental equipment. A small artificial hole was introduced onto the specimen surface. Fatigue crack initiated from the artificial hole. A small portable strain histogram recorder (Mini Rainflow Corder, MRC) developed in another project of the authors' team was used to acquire the service strain hisogram at a critical point of the specimen and to measure the variation of natural frequency. Cumulative fatigue damage D defined by the Modified Miner Rule was calculated by using the strain histogram at the initial stage of test. The value of D was almost unity in the case of In-line vibration, while the values of D in the case of the Cross-flow vibration ranged from 0.2 to 0.8. (author)

Construction of a Vibration Monitoring System for HANARO's Rotating Machinery and Analysis of Pump Vibration Signals

International Nuclear Information System (INIS)

Ryu, Jeong Soo; Yoon, Doo Byung

2005-01-01

HANARO is an open-tank-in-pool type research reactor with a thermal power of 30MW. In order to remove the heat generated by the reactor core and the reflector vessel, primary cooling pumps and reflector cooling pumps circulate coolant. These pumps are installed at the RCI(Reactor Concrete Island) which is covered by heavy concrete hatches. For the prevention of an abnormal operation of these pumps in the RCI, it is necessary to construct a vibration monitoring system that provides an alarm signal to the reactor control room when the rotating speed or the vibration level exceeds the allowable limit. The first objective of this work is to construct a vibration monitoring system for HANARO's rotating machinery. The second objective is to verify the possibility of condition monitoring of the rotating machinery. To construct a vibration monitoring system, as a first step, the standards and references related to the vibration monitoring system were investigated. In addition, to determine the number and the location of sensors that can effectively characterize the overall vibration of a pump, the vibration of the primary cooling pumps and the reflector cooling pumps were measured. Based on these results, detailed construction plans for the vibration monitoring system for HANARO were established. Then, in accordance with the construction plans, the vibration monitoring system for HANARO's rotating machinery was manufactured and installed at HANARO. To achieve the second objective, FFT analysis and bearing fault detection of the measured vibration signals were performed. The analysis results demonstrate that the accelerometers mounted at the bearing locations of the pumps can effectively monitor the pump condition

An inverse method for identification of a distributed random excitation acting on a vibrating structure flow-induced vibration application

International Nuclear Information System (INIS)

Perotin, L.; Granger, S.

1997-01-01

In order to improve the prediction of wear problems due to flow-induced vibration in PWR components, an inverse method for identifying a distributed random excitation acting on a dynamical system has been developed at EDF. This method, whose applications go far beyond the flow-induced vibration field, has been implemented into the MEIDEE software. This method is presented. (author)

A Comparative Study of Ground and Underground Vibrations Induced by Bench Blasting

Directory of Open Access Journals (Sweden)

Xiuzhi Shi

2016-01-01

Full Text Available Ground vibrations originating from bench blasting may cause damage to slopes, structures, and underground workings in close proximity to an operating open-pit mine. It is important to monitor and predict ground vibration levels induced by blasting and to take measures to reduce their hazardous effects. The aims of this paper are to determine the weaker protection objects by comparatively studying bench blasting induced vibrations obtained at surface and in an underground tunnel in an open-pit mine and thus to seek vibration control methods to protect engineering objects at the site. Vibrations arising from measurement devices at surface and in an underground tunnel at the Zijinshan Open-Pit Mine were obtained. Comparative analysis of the peak particle velocities shows that, in the greatest majority of cases, surface values are higher than underground values for the same vibration distance. The transmission laws of surface and underground vibrations were established depending on the type of rock mass, the explosive charge, and the distance. Compared with the Chinese Safety Regulations for Blasting (GB6722-2014, the bench blasting induced vibrations would not currently cause damage to the underground tunnel. According to the maximum allowable peak particle velocities for different objects, the permitted maximum charges per delay are obtained to reduce damage to these objects at different distances.

Flow-induced vibration of circular cylindrical structures

International Nuclear Information System (INIS)

Chen, S.S.

1985-06-01

This report summarizes the flow-induced vibration of circular cylinders in quiescent fluid, axial flow, and crossflow, and applications of the analytical methods and experimental data in design evaluation of various system components consisting of circular cylinders. 219 figs., 30 tabs

Flow induced vibrational excitation of nuclear reactor structures

International Nuclear Information System (INIS)

Gibert, R.J.

1979-01-01

The pressure fluctuations generated by disturbed flows, encountered in nuclear reactors induce vibrations in the structures. In order to make forecastings for these vibrational levels, it is necessary to know the characteristics of the random pressure fluctuations induced in the walls by the main flow peculiarities of the circuits. This knowledge is essentially provided by experimentation which shows that most of the energy from these fluctuations is in the low frequency area. It is also necessary to determine the transfer functions of the fluid-structure coupled system. Given the frequency range of the excitations, a calculation of the characteristics of the first eigenmodes is generally sufficient. This calculation is carried out by finite element codes, the modal dampings being assessed separately. In this paper, emphasis is placed mainly on the analysis of the sources of excitation due to flow peculiarities. Some examples will also be given of assessments of vibrations in real structures (pipes, reactor internals, etc.) and of comparisons with the experimental results obtained on models or on a site [fr

Evaluation of human-induced vibration of continuous footbridges

Directory of Open Access Journals (Sweden)

El-Robaa Ahmed

2015-01-01

Full Text Available With the development of construction materials and the introduction of high strength steel and concrete, the human-induced vibration became a dominant criterion for the design of pedestrian bridges. Currently, longer spans and lightweight bridges have been comprised in most of design trends. This leads to lower the natural frequencies of the system which have a great effect on the dynamic performance of bridges subjected to human activities. Although the design of steel footbridges could reach the optimum level of design in terms of strength criterion, it might not reach the acceptance level for vibration condition. This will enforce the designer to choose section profiles with higher inertia to enhance stiffness of the whole system. This paper presents an overall assessment for floor vibration problem due to pedestrian induced vertical forces on continuous composite footbridges. The footfall method presented by concrete centre “CCIP-016” is adopted in this study to evaluate the response factor and acceleration of pedestrian bridges using a FEA software package “Robot Structural Analysis”.

Cooling Performance of ALIP according to the Air or Sodium Cooling Type

Energy Technology Data Exchange (ETDEWEB)

Ye, Huee-Youl; Yoon, Jung; Lee, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

ALIP pumps the liquid sodium by Lorentz force produced by the interaction of induced current in the liquid metal and their associated magnetic field. Even though the efficiency of the ALIP is very low compared to conventional mechanical pumps, it is very useful due to the absence of moving parts, low noise and vibration level, simplicity of flow rate regulation and maintenance, and high temperature operation capability. Problems in utilization of ALIP concern a countermeasure for elevation of internal temperature of the coil due to joule heating and how to increase magnetic flux density of Na channel gap. The conventional ALIP usually used cooling methods by circulating the air or water. On the other hand, GE-Toshiba developed a double stator pump adopting the sodium-immersed self-cooled type, and it recovered the heat loss in sodium. Therefore, the station load factor of the plant could be reduced. In this study, the cooling performance with cooling types of ALIP is analyzed. We developed thermal analysis models to evaluate the cooling performance of air or sodium cooling type of ALIP. The cooling performance is analyzed for operating parameters and evaluated with cooling type. 1-D and 3-D thermal analysis model for IHTS ALIP was developed, and the cooling performance was analyzed for air or sodium cooling type. The cooling performance for air cooling type was better than sodium cooling type at higher air velocity than 0.2 m/s. Also, the air temperature of below 270 .deg. demonstrated the better cooling performance as compared to sodium.

Plate-fin array cooling using a finger-like piezoelectric fan

International Nuclear Information System (INIS)

Shyu, Jin-Cherng; Syu, Jhih-Zong

2014-01-01

In this study, the heat transfer of a plate-fin array cooled by a vibrating finger-like piezoelectric fan comprising four flexible rectangular blades was investigated. The results indicated that the heat transfer enhancement of the fin array cooled by a vibrating piezoelectric fan at x/L = 0.5 and H = 5 mm ranged between 1.5 and 3.3, regardless of the fin array orientation. However, the heat transfer enhancement caused by a fan being placed at either edge of the fin array yielded a dissimilar result between both of the fin array orientations because of the superimposed effects of the boundary layer development and the air flow induced by the fan. This dissimilarity was especially noticeable when the piezoelectric fan was composed of aluminum blades to accommodate the moderate Reynolds number. In addition to the Reynolds number, the ratio of the fan blade vibration envelope to the source area determined the Nu number of the piezoelectric fan-cooled fin array. This design enhanced the fin array heat transfer and reduced cooler volume by embedding multiple vibrating beams into the fin array. -- Highlights: • Heat transfer of a piezoelectric fan-cooled plate-fin array was investigated. • Effects of fan position, fan height and fan material on heat transfer were examined. • Similar heat transfer enhancement range was shown for both fin array orientations. • Fin heat transfer with a running Al fan at x = 0 was higher than that at x = 0.25L. • Besides fan Reynolds number, the area ratio also determined Nu of the fin array

Two-phase flow induced parametric vibrations in structural systems

International Nuclear Information System (INIS)

Hara, Fumio

1980-01-01

This paper is divided into two parts concerning piping systems and a nuclear fuel pin system. The significant experimental results concerning the random vibration induced in an L-shaped pipe by air-water two-phase flow and the theoretical analysis of the vibration are described in the first part. It was clarified for the first time that the parametric excitation due to the periodic changes of system mass, centrifugal force and Coriolis force was the mechanism of exciting the vibration. Moreover, the experimental and theoretical analyses of the mechanism of exciting vibration by air-water two-phase flow in a straight, horizontal pipe were carried out, and the first natural frequency of the piping system was strongly related to the dominant frequency of void signals. The experimental results on the vibration of a nuclear fuel pin model in parallel air-water two-phase flow are reported in the latter part. The relations between vibrational strain variance and two-phase flow velocity or pressure fluctuation, and the frequency characteristics of vibrational strain variance were obtained. The theoretical analysis of the dynamic interaction between air-water two-phase flow and a fuel pin structure, and the vibrational instability of fuel pins in alternate air and water slugs or in large bubble flow are also reported. (Kako, I.)

Measurements of ground motion and magnet vibrations at the APS

International Nuclear Information System (INIS)

Shiltsev, V.

1996-01-01

This article presents results of ground motion and magnet vibrations measurements at the Advanced Photon Source. The experiments were done over a wide, frequency range (0-05-100 Hz) with the use of SM-3KV-type seismic probes from the Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. Also investigated were magnet vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quadrupole vibrations at different sectors of the ring. The influence of personnel activity in the hall and traffic under the ring on the slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators

Induced vibrations facilitate traversal of cluttered obstacles

Science.gov (United States)

Thoms, George; Yu, Siyuan; Kang, Yucheng; Li, Chen

When negotiating cluttered terrains such as grass-like beams, cockroaches and legged robots with rounded body shapes most often rolled their bodies to traverse narrow gaps between beams. Recent locomotion energy landscape modeling suggests that this locomotor pathway overcomes the lowest potential energy barriers. Here, we tested the hypothesis that body vibrations induced by intermittent leg-ground contact facilitate obstacle traversal by allowing exploration of locomotion energy landscape to find this lowest barrier pathway. To mimic a cockroach / legged robot pushing against two adjacent blades of grass, we developed an automated robotic system to move an ellipsoidal body into two adjacent beams, and varied body vibrations by controlling an oscillation actuator. A novel gyroscope mechanism allowed the body to freely rotate in response to interaction with the beams, and an IMU and cameras recorded the motion of the body and beams. We discovered that body vibrations facilitated body rolling, significantly increasing traversal probability and reducing traversal time (P locomotor pathways in complex 3-D terrains.

Topographic analysis of the skull vibration-induced nystagmus test with piezoelectric accelerometers and force sensors.

Science.gov (United States)

Dumas, Georges; Lion, Alexis; Perrin, Philippe; Ouedraogo, Evariste; Schmerber, Sébastien

2016-03-23

Vibration-induced nystagmus is elicited by skull or posterior cervical muscle stimulations in patients with vestibular diseases. Skull vibrations delivered by the skull vibration-induced nystagmus test are known to stimulate the inner ear structures directly. This study aimed to measure the vibration transfer at different cranium locations and posterior cervical regions to contribute toward stimulus topographic optimization (experiment 1) and to determine the force applied on the skull with a hand-held vibrator to study the test reproducibility and provide recommendations for good clinical practices (experiment 2). In experiment 1, a 100 Hz hand-held vibrator was applied on the skull (vertex, mastoids) and posterior cervical muscles in 11 healthy participants. Vibration transfer was measured by piezoelectric sensors. In experiment 2, the vibrator was applied 30 times by two experimenters with dominant and nondominant hands on a mannequin equipped to measure the force. Experiment 1 showed that after unilateral mastoid vibratory stimulation, the signal transfer was higher when recorded on the contralateral mastoid than on the vertex or posterior cervical muscles (Pskull vibration-induced nystagmus test in patients with unilateral vestibular lesions and enables a stronger stimulation of the healthy side. In clinical practice, the vibrator should be placed on the mastoid and should be held by the clinician's dominant hand.

A numerical method to calculate flow-induced vibrations in a turbulent flow

International Nuclear Information System (INIS)

Sadaoka, Noriyuki; Umegaki, Kikuo

1993-01-01

An unsteady fluid force on structures in a turbulent flow can cause their vibration. The phenomenon is the most important among various flow-induced vibrations and it is an important subject in design nuclear plant components such as heat exchangers. A new approach to simulate flow-induced vibrations is introduced. A fully coupled analysis of fluid-structure interaction has been realized in a turbulent flow field by integrating the following calculational steps: (a) solving turbulent flow by a direct simulation method where the ALE (arbitrary Lagrangian Eulerian) type approximation is adopted to take account of structure displacements; (b) estimating fluid force on structures by integrating fluid pressure and shear stress; (c) calculating dynamic response of structures and determining the amount of displacement; (d) regenerate curvilinear grids for new geometry using the boundary-fitted coordinate transformation method. Forced vibration of a circular cylinder in a cross flow were successfully simulated and the synchronization phenomena between Karman-vortices and cylinder vibrations were clearly seen

Induced vibrations increase performance of a winged self-righting robot

Science.gov (United States)

Othayoth, Ratan; Xuan, Qihan; Li, Chen

When upside down, cockroaches can open their wings to dynamically self-right. In this process, an animal often has to perform multiple unsuccessful maneuvers to eventually right, and often flails its legs. Here, we developed a cockroach-inspired winged self-righting robot capable of controlled body vibrations to test the hypothesis that vibrations assist self-righting transitions. Robot body vibrations were induced by an oscillating mass (10% of body mass) and varied by changing oscillation frequency. We discovered that, as the robot's body vibrations increased, righting probability increased, and righting time decreased (P locomotor transitions, but highlights the need for further stochastic modeling to capture the uncertain nature of when righting maneuvers result in successful righting.

Self-induced vibrations of a DU96-W-180 airfoil in stall

DEFF Research Database (Denmark)

Skrzypinski, Witold Robert; Gaunaa, Mac; Sørensen, Niels N.

2014-01-01

This work presents an analysis of two-dimensional (2D) and three-dimensional (3D) non-moving, prescribed motion and elastically mounted airfoil computational fluid dynamics (CFD) computations. The elastically mounted airfoil computations were performed by means of a 2D structural model with two...... degrees of freedom. The computations aimed at investigating the mechanisms of both vortex-induced and stall-induced vibrations related to a wind turbine blade at standstill conditions. In this work, a DU96-W-180 airfoil was used in the angle-of-attack region potentially corresponding to stallinduced...... vibrations. The analysis showed significant differences between the aerodynamic stability limits predicted by 2D and 3D CFD computations. A general agreement was reached between the prescribed motion and elastically mounted airfoil computations. 3D computations indicated that vortex-induced vibrations...

Flow-induced vibration analysis of heat exchanger and steam generator designs

International Nuclear Information System (INIS)

Pettigrew, M.J.; Sylvestre, Y.; Campagna, A.O.

1977-08-01

Tube and shell heat exchange components such as steam generators, heat exchangers and condensers are essential parts of CANDU nuclear power stations. Excessive flow-induced vibration may cause tube failures by fatigue or more likely by fretting-wear. Such failures may lead to station shutdowns that are very undesirable in terms of lost production. Hence good performance and reliability dictate a thorough flow-induced vibration analysis at the design stage. This paper presents our approach and techniques in this respect. (author)

Experimental study of flow induced vibration of the planar fuel assembly

International Nuclear Information System (INIS)

Wang Jinhua; Bo Hanliang; Jiang Shengyao; Jia Haijun; Zheng Wenxiang; Min Gang; Qu Xinxing

2005-01-01

The paper studied the flow-induced vibration of the planar fuel assembly under scour of coolant through experiments, the study includes: the characteristics of the inherent vibration, the response to the flow-induced vibration in rating condition and the confirmation of the critical flow velocity's scope of the flow flexible instability. The velocity distributions in different flow channels formed by fuel plates in the assembly were measured, and the velocity distribution in the same flow channel was also measured. The experimental conclusions includes: the inherent vibration frequency of the planar fuel assembly is different for a little in each direction. The damp ratio corresponding to the assembly each rank's inherent frequency is small, and the damp ratio decreased with the increase of the corresponding inherent frequency. The velocity in different flow channels decreased from outside to inside, and the velocity in the middle channel was the least; the velocity in the same channel decreased from inside to outside, and the velocity in the middle position was the most. The vibration swing of the fuel assembly was small at rating condition, and the vibration swing of the fuel plates was larger than side plates. The vibration of the fuel assembly increased with the increase of the velocity, the vibration of the middle fuel plate were larger than the border fuel plate, and the vibration of the border fuel plate was larger than the side plate. The large scale vibration of the flow flexible instability didn't occur in the velocity scope of 0-18.8 m/s in the experiment, so the critical flow velocity of the flow flexible instability was not in the flow velocity scope of the experiment. (authors)

Adsorbate-driven cooling of carbene-based molecular junctions

Czech Academy of Sciences Publication Activity Database

Foti, Giuseppe; Vázquez, Héctor

2017-01-01

Roč. 8, Oct (2017), s. 2060-2068 ISSN 2190-4286 R&D Projects: GA ČR GA15-19672S EU Projects: European Commission(XE) 702114 - HEATEXMOL Institutional support: RVO:68378271 Keywords : adsorbate * carbene * current-induced heating and cooling * molecular junction * vibrations Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.127, year: 2016

A study on mechanical properties and flow-induced vibrations of coil-shaped holddown spring

International Nuclear Information System (INIS)

Kim, Kyu-Tae

2010-01-01

The fuel assemblies used in the OPR1000s in Korea employ four coil-shaped hold-down springs to exert compressive load at the top of fuel assembly so that the assemblies may not be damaged by preventing its hydraulic-induced lifting-off from its lower seating surface. However, the coolant flow generates the flow-induced vibration at the coil-shaped hold-down springs which may cause wear on the spring surfaces. A hold-own spring may be fractured if torsional stress acting on its worn area exceeds a stress limit, resulting in the loss of hold-down spring force of the fuel assembly. In this paper, flow-induced vibration tests were performed for standard and improved coil type hold-down springs to investigate the effects of these two hold-down spring designs on flow-induced vibration wear. In parallel, a wide spectrum of mechanical tests was performed to obtain vibration-related characteristics of these two hold-down springs, which can be used as input data for the fuel assembly static and dynamic analysis. It is found that the improved hold-down spring design is better against flow-induced vibration wear than the standard one. With the use of the three-dimensional Solidwork model, the stress-related design lifetime of the improved hold-down spring was estimated by extrapolating its wear data measured from the flow-induced vibration tests, which indicates that the improved HD spring design will maintain integrity during the fuel design lifetime in OPR1000s in Korea.

Flow induced vibrations in gas tube assembly of centrifuge

International Nuclear Information System (INIS)

Alam, M.; Atta, M.A.; Mirza, J.A.; Khan, A.Q.

1986-01-01

A centrifuge essentially consists of a rotor rotating at very high speed. Gas tube assembly, located at the center of the rotor, is used to introduce feed gas into the rotor and remove product and waste streams from it. The gas tube assembly is thus a static component, the product and waste scoops of which are lying in the high pressure region of a fluid rotating at very high speed. This can cause flow induced vibrations in the gas tube assembly. Such vibrations affect not only the mechanical stability of the gas tube assembly but may also reduce the separative power of the centrifuge. In a cascade, if some of the centrifuges have gas tube vibration, then cascade performance will be affected. A theoretical analysis of the effect of waste tube vibrations on product and waste flow rates and pressures in the centrifuge is presented. A simple stage consisting of two centrifuges, in which one has tube vibration, is considered for this purpose. The results are compared with experiment. It is shown that waste tube vibration generates oscillations in waste and product flow rates that are observable outside the centrifuge. (author)

Prediction of dynamic loads and induced vibrations in stall

Energy Technology Data Exchange (ETDEWEB)

Thirstrup Petersen, J.; Aagaard Madsen, H. [Risoe National Lab. (Denmark); Bjoerck, A. [Aeronautical Research Inst. of Sweden (Sweden); Enevoldsen, P. [Bonus Energy A/S (Denmark); Oeye, S. [The Technical Univ. of Denmark (Denmark); Ganander, H. [Teknikgruppen AB (Sweden); Winkelaar, D. [Netherlands Energy Research Foundation (Netherlands)

1998-05-01

Results from research in an EC Joule-III project and from national projects are presented. The objectives are improvement of design methods for stall regulated wind turbines with emphasis on stall induced vibrations and dynamic stall. The primary concern is limitation of the edgewise vibrations in the fundamental blade natural mode shape, which have caused trouble on modern wind turbines of approximate size 500 kW nominal power and 40 m rotor diameter. A theoretical study of quasi-steady aerodynamics confirms that the vibrations are driven basically by energy supplied from the aerodynamic forces during stalled operation. This energy exchange is equivalent to negative aerodynamic damping. The theoretical approach identifies the main parameters controlling the phenomenon. These parameters describe the steady and the dynamic airfoil characteristics, the overall aerodynamic layout of the blade, e.g. chord length and twist, the structural properties of the blade, e.g. structural damping and properties controlling the resulting vibration direction. Furthermore, full aeroelastic calculations and comparison with measurements show that the properties of the supporting structure, i.e. the main shaft, the nacelle and the tower, are important, as the global vibration of the rotor on its support may exchange energy with the blade vibration, when the blade natural frequency is close to one of the frequencies of the coupled rotor tilt-yaw mode shapes, usually denoted the global rotor whirl frequencies. It is confirmed that the influence of changing the primary design parameters can be determined by use of qualified aeroelastic calculations. Presented design guidelines therefore build on both the simple quasi-steady models, which can be used for the preliminary choice of the design variables mentioned above, and on full aeroelastic calculations. The aeroelastic calculations refine the design basis and should be used for choosing the final design variables and for final

Fuel Rod Flow-Induced Vibration Overview

Energy Technology Data Exchange (ETDEWEB)

Lee, Kang Hee; Kang, Heung Seok; Kim, Hyung Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-10-15

To ensure fuel design safety and structural integrity requires the response prediction of fuel rod to reactor coolant flow excitation. However, there are many obstacles in predicting the response as described. Even if the response can be predicted, the design criteria on wear failure, including correlation with the vibration, may be difficult to establish because of a variety of related parameters, such as material, surface condition and environmental factors. Thus, a prototype test for each new fuel assembly design, i.e. a long-term endurance test, is performed for design validation with respect to flow-induced vibration (FIV) and wear. There are still needs of theoretical prediction methods for the response and anticipated failure. This paper revisits the general aspect on the response prediction, mathematical description, analysis procedure and wear correlation aspect of fuel rod's FIV

Neuropathic pain-like alterations in muscle nociceptor function associated with vibration-induced muscle pain.

Science.gov (United States)

Chen, Xiaojie; Green, Paul G; Levine, Jon D

2010-11-01

We recently developed a rodent model of the painful muscle disorders induced by occupational exposure to vibration. In the present study we used this model to evaluate the function of sensory neurons innervating the vibration-exposed gastrocnemius muscle. Activity of 74 vibration-exposed and 40 control nociceptors, with mechanical receptive fields in the gastrocnemius muscle, were recorded. In vibration-exposed rats ∼15% of nociceptors demonstrated an intense and long-lasting barrage of action potentials in response to sustained suprathreshold mechanical stimulation (average of 2635 action potentials with frequency of ∼44Hz during a 1min suprathreshold stimulus) much greater than that has been reported to be produced even by potent inflammatory mediators. While these high-firing nociceptors had lower mechanical thresholds than the remaining nociceptors, exposure to vibration had no effect on conduction velocity and did not induce spontaneous activity. Hyperactivity was not observed in any of 19 neurons from vibration-exposed rats pretreated with intrathecal antisense for the IL-6 receptor subunit gp130. Since vibration can injure peripheral nerves and IL-6 has been implicated in painful peripheral neuropathies, we suggest that the dramatic change in sensory neuron function and development of muscles pain, induced by exposure to vibration, reflects a neuropathic muscle pain syndrome. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Contributions of the Higher Vibrational Levels of Nitric Oxide to the Radiative Cooling of the Thermosphere

Science.gov (United States)

Venkataramani, K.; Yonker, J. D.; Bailey, S. M.

2014-12-01

The 5.3μm emission from the vibrational levels of nitric oxide (NO) and the 15μm emission from CO2 are known to be the dominant sources of cooling in the thermosphere above 100 km. The 5.3μm emission is primarily produced by the radiative de-excitation of NO from its first vibrational level, which in turn is mainly populated by the collisions of NO with atomic oxygen. However, the reaction of atomic nitrogen (N(4S) and N(2D)) with O2 yields vibrationally excited NO with v>1, resulting in a radiative cascade which produces more than one 5.3μm photon per vibrationally excited NO molecule. This chemiluminescence is approximately 20% in magnitude of the emission produced by thermal collisions. These additional sources of the 5.3μm emission are introduced into a one dimensional photochemical model and the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) to assess their variability with latitude and solar activity, and to also understand their effect on the thermospheric energy budget. The results from the models are compared with data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment on-board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, which has been making measurements of the infrared radiative response of the mesosphere and thermosphere to solar inputs since 2002.

Flow-induced vibrations of circular cylindrical structures

International Nuclear Information System (INIS)

Chen, S.

1977-06-01

The problems of flow-induced vibrations of circular cylindrical structures are reviewed. First, the general method of analysis and classification of structural responses are presented. Then, the presentation is broken up along the lines with stationary fluid, parallel flow, and cross flow. Finally, design considerations and future research needs are pointed out. 234 references

Development of Design Criteria for Fluid Induced Structural Vibrations in Steam Generators and Heat Exchangers

International Nuclear Information System (INIS)

Uvan Catton; Dhir, Vijay K.; Deepanjan Mitra; Omar Alquaddoomi; Pierangelo Adinolfi

2004-01-01

Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-induced vibration is constantly updated with new findings and improved design criteria for heat exchangers

Measurements of ground motion and magnets vibrations at the APS

International Nuclear Information System (INIS)

Shil'tsev, V.D.

1994-01-01

This article presents results of ground motion and magnets vibrations measurements at the Advanced Photon Source. The experiments were done over wide frequency range 0.05-100 Hz with use of SM-3KV type seismic probes from Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. There were also investigated magnets vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quads vibration at different sectors of the ring. Influence of personnel activity in the hall and traffic under the ring on slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators. 9 refs.; 10 figs.; 1 tab

Numerical modeling of deformation and vibrations in the construction of large-size fiberglass cooling tower fan

Directory of Open Access Journals (Sweden)

Fanisovich Shmakov Arthur

2016-01-01

Full Text Available This paper presents the results of numerical modeling of deformation processes and the analysis of the fundamental frequencies of the construction of large-size fiberglass cooling tower fan. Obtain the components of the stress-strain state structure based on imported gas dynamic and thermal loads and the form of fundamental vibrations. The analysis of fundamental frequencies, the results of which have been proposed constructive solutions to reduce the probability of failure of the action of aeroelastic forces.

Flow induced vibrations of piping

International Nuclear Information System (INIS)

Gibert, R.J.; Axisa, F.

1977-01-01

In order to design the supports of piping systems, estimations of the vibrations induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary to calculate the model parameters of liquid containing pipes. In most computer codes, fluid effects are accounted for just by adding the fuid mass to the structure. This may lead to serious errors.- Inertial effects from the fluid are not correctly evaluated especially in the case of bended or of non-uniform section pipes. Fluid boundary conditions are simply ignored. - In many practical problems fluid compressibility cannot be negelcted, even in the low frequencies domain which corresponds to efficient excitation by turbulent sources of the flow. This paper presents a method to take into account these efects, by solving a coupled mechanical acoustical problem: the computer code TEDEL of the C.E.A./D.E.M.T. System, based on the finite-elements method, has been extended to calculate simultaneously the pressure fluctuations in the fluid and the vibrations of the pipe. (Auth.)

CRBRP flow induced vibration program

Energy Technology Data Exchange (ETDEWEB)

Novendstern, E H [Westinghouse Advanced Reactor Division, Madison, PA (United States); Grochowski, F A; Yang, T M [General Electric Co., Fast Breeder Reactor Department, Sunnyvale, CA (United States); Ryan, J A; Mulcahy, T M

1977-12-01

The program to assure the structural adequacy of Clinch River Breeder Reactor (CRBRP) components during its planned 30 years of operation is described. The program includes (1) an assessment of reactor components relative to their susceptibility to FIV, (2) designing to minimize component excitation due to Fluid induced vibrations (FIV), (3) scale model tests to measure structural response during simulated operating conditions and (4) preoperational tests. An overview of the CRBRP test program is described. Additionally, details of scale model testing of reactor internals and the steam generator is described in more detail. (author)

Vibration-Induced Errors in MEMS Tuning Fork Gyroscopes with Imbalance.

Science.gov (United States)

Fang, Xiang; Dong, Linxi; Zhao, Wen-Sheng; Yan, Haixia; Teh, Kwok Siong; Wang, Gaofeng

2018-05-29

This paper discusses the vibration-induced error in non-ideal MEMS tuning fork gyroscopes (TFGs). Ideal TFGs which are thought to be immune to vibrations do not exist, and imbalance between two gyros of TFGs is an inevitable phenomenon. Three types of fabrication imperfections (i.e., stiffness imbalance, mass imbalance, and damping imbalance) are studied, considering different imbalance radios. We focus on the coupling types of two gyros of TFGs in both drive and sense directions, and the vibration sensitivities of four TFG designs with imbalance are simulated and compared. It is found that non-ideal TFGs with two gyros coupled both in drive and sense directions (type CC TFGs) are the most insensitive to vibrations with frequencies close to the TFG operating frequencies. However, sense-axis vibrations with in-phase resonant frequencies of a coupled gyros system result in severe error outputs to TFGs with two gyros coupled in the sense direction, which is mainly attributed to the sense capacitance nonlinearity. With increasing stiffness coupled ratio of the coupled gyros system, the sensitivity to vibrations with operating frequencies is cut down, yet sensitivity to vibrations with in-phase frequencies is amplified.

Effect of top ligament blanking on reducing flow induced vibration of protective grid

Energy Technology Data Exchange (ETDEWEB)

Eom, Kyong Bo; Ryu, Joo Young; Kwon, Oh Joon; Park, Joon Kyoo; Jeon, Sang Youn; Suh, Jung Min [KEPCO NF Co., Daejeon (Korea, Republic of)

2012-10-15

The protective grid is a Inconel 718 spacer grid located just above the bottom nozzle in many kinds of fuel assemblies for PWR. The purpose of using protective grid is to capture debris before they flow up into the fuel assembly and get trapped by the other grids causing fuel rod damages as well as to provide support at the lower end plugs of fuel rods. Recently, it has been reported that strap failure has occurred in the protective grids and the flow induced vibration of the strap has resulted in the strap fatigue failure. After the root cause of the protective grid failure was found to be the flow induced vibration of the strap, KEPCO NF has made an effort to find the vibration tendencies of grid strap and draw vibration mitigation concepts of the protective grid strap. The vibration tendency and the effect of the vibration mitigation concept of the protective grid which have been found by the results of the loop tests and simulations in KEPCO NF are presented herein.

Quantum limits of photothermal and radiation pressure cooling of a movable mirror

International Nuclear Information System (INIS)

Pinard, M; Dantan, A

2008-01-01

We present a general quantum-mechanical theory for the cooling of a movable mirror in an optical cavity when both radiation pressure self-cooling and photothermal cooling effects are present, and show that these two mechanisms may bring the oscillator close to its quantum ground state, although in quite different regimes. Self-cooling caused by coherent exchange of excitations between the cavity mode and the mirror vibrational mode is shown to dominate in the good-cavity regime-when the mechanical resonance frequency is larger than the cavity decay rate, whereas photothermal-induced cooling can be made predominant in the bad-cavity limit. Both situations are compared, and the relevant physical quantities to be optimized in order to reach the lowest final excitation number states are extracted.

Fluid-Induced Vibration Analysis for Reactor Internals Using Computational FSI Method

Energy Technology Data Exchange (ETDEWEB)

Moon, Jong Sung; Yi, Kun Woo; Sung, Ki Kwang; Im, In Young; Choi, Taek Sang [KEPCO E and C, Daejeon (Korea, Republic of)

2013-10-15

This paper introduces a fluid-induced vibration analysis method which calculates the response of the RVI to both deterministic and random loads at once and utilizes more realistic pressure distribution using the computational Fluid Structure Interaction (FSI) method. As addressed above, the FIV analysis for the RVI was carried out using the computational FSI method. This method calculates the response to deterministic and random turbulence loads at once. This method is also a simple and integrative method to get structural dynamic responses of reactor internals to various flow-induced loads. Because the analysis of this paper omitted the bypass flow region and Inner Barrel Assembly (IBA) due to the limitation of computer resources, it is necessary to find an effective way to consider all regions in the RV for the FIV analysis in the future. Reactor coolant flow makes Reactor Vessel Internals (RVI) vibrate and may affect the structural integrity of them. U. S. NRC Regulatory Guide 1.20 requires the Comprehensive Vibration Assessment Program (CVAP) to verify the structural integrity of the RVI for Fluid-Induced Vibration (FIV). The hydraulic forces on the RVI of OPR1000 and APR1400 were computed from the hydraulic formulas and the CVAP measurements in Palo Verde Unit 1 and Yonggwang Unit 4 for the structural vibration analyses. In this method, the hydraulic forces were divided into deterministic and random turbulence loads and were used for the excitation forces of the separate structural analyses. These forces are applied to the finite element model and the responses to them were combined into the resultant stresses.

Evaluation of blast-induced vibration effects on structures 1

Energy Technology Data Exchange (ETDEWEB)

Lee, Jong Rim; Jeon, Gyu Shick; Lee, Dae Soo; Joo, Kwang Ho; Lee, Woong Keon [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of); Ryu, Chang Ha; Chung, So Keul; Lee, Kyung Won; Shin, Hee Soon; Chun, Sun Woo; Park, Yeon Jun; Synn, Joong Ho; Choi, Byung Hee [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

1995-12-31

Due to the difficulties of obtaining construction site for new plants, following ones are inevitably being built in the site adjacent to existing power plants. Therefore considerable thought has been recently given to the dynamic loading generated by blasting works near the plants to maintain the safety of structures and facilities in power plants. Our own standard for safety level of blast vibration is not prepared yet, and foreign standards have been generally employed without theoretical and experimental verification. Safety-related structures of power plants and facilities have to be protected against the effects of possible hazards due to blast vibration. Earthquakes have been considered a major dynamic design loading as a requirement of plant design, but the effects of blast-induced vibration are not. In order to ensure the safety, rational safe criterion should be established and blast design should be satisfy it, which requires the development of a model for prediction of vibration level through more systematic measurement and analysis. The main objectives of the study are : to provide background data for establishing the rational safe vibration limits, to develop models for prediction of blast vibration level, to establish safe blast design criterion, and to accumulate techniques for field measurements, data acquisition and analysis (author). 80 refs., 347 figs.

Current pathophysiological views on vibration-induced Raynaud's phenomenon.

Science.gov (United States)

Stoyneva, Z; Lyapina, M; Tzvetkov, D; Vodenicharov, E

2003-03-01

This review attempts to summarize and discuss contemporary pathogenetic views on vibration-induced Raynaud's phenomenon assuming its multifactorial etiology. An increase in central and peripheral sympathetic nervous activity is discussed based on different physiological indicators of autonomic dysfunction and sympathetic hyperactivity. Local acral vasodysregulation is considered. Receptor and nerve endings dysfunction presented with predominance of alpha(2)-receptor function in the digital arteries and neuronal loss in those digital cutaneous perivascular nerves containing calcitonin gene-related peptide result in deficiency of endogenous release of this powerful vasodilator. Endothelial damage and dysregulation induced by vibration and increased shear stresses are demonstrated by the elevated plasma level of thrombomodulin and of von Willebrand factor and reduced endothelium-dependent vasodilator responses. The concentrations of endothelin-1 are high, the highest being in most advanced stages. Decreased plasma thiol level, indicating increased production and activity of free radicals, contribute to vasospastic paroxysms in vibration white finger patients. Dysbalance of local vasoactive factors with opposing effects on vascular smooth muscle like endothelin and nitric oxide, endothelin and calcitonin gene-related peptide, nitric oxide and superoxide anion are discussed. Disturbed smooth muscle response is supposed. Changes in hemostasis, fibrinolysis and hemorrheology, activation of blood cells with erythrocyte hyperaggregation and red cell hypodeformability, platelet aggregation with increased release of vasoconstricting thromboxane A(2) and serotonin as well as leukocyte activation, entrapment within capillaries and post-capillary venules and increased reactive oxygen species and lysosomal lytic enzymes release might also contribute to digital vasospasms and tissue damage. Elevated soluble intercellular adhesion molecule-1 levels involved in the adherence of

Flow Induced Vibration Program at Argonne National Laboratory

Science.gov (United States)

1984-01-01

The Argonne National Laboratory's Flow Induced Vibration Program, currently residing in the Laboratory's Components Technology Division is discussed. Throughout its existence, the overall objective of the program was to develop and apply new and/or improved methods of analysis and testing for the design evaluation of nuclear reactor plant components and heat exchange equipment from the standpoint of flow induced vibration. Historically, the majority of the program activities were funded by the US Atomic Energy Commission, the Energy Research and Development Administration, and the Department of Energy. Current DOE funding is from the Breeder Mechanical Component Development Division, Office of Breeder Technology Projects; Energy Conversion and Utilization Technology Program, Office of Energy Systems Research; and Division of Engineering, Mathematical and Geosciences, office of Basic Energy Sciences. Testing of Clinch River Breeder Reactor upper plenum components was funded by the Clinch River Breeder Reactor Plant Project Office. Work was also performed under contract with Foster Wheeler, General Electric, Duke Power Company, US Nuclear Regulatory Commission, and Westinghouse.

Full-scale investigation of wind-induced vibrations of mast-arm traffic signal structures.

Science.gov (United States)

2014-08-01

Because of their inherent : fl : exibility and low damping ratios, cantilevered mast : - : arm : tra : ffi : c signal structures are suscepti : b : le to : wind : - : induced vibrations. : These vibrations : cause stru : ctural stresses and strains t...

Study on Fluid-Induced Vibration Power Harvesting of Square Columns under Different Attack Angles

Directory of Open Access Journals (Sweden)

Meng Zhang

2017-01-01

Full Text Available A model of the flow-vibration-electrical circuit multiphysical coupling system for solving square column vortex-induced vibration piezoelectric energy harvesting (VIVPEH is proposed in this paper. The quasi steady state theory is adopted to describe the fluid solid coupling process of vortex-induced vibration based on the finite volume method coupled Gauss equation. The vibrational response and the quasi steady state form of the output voltage are solved by means of the matrix coefficient method and interactive computing. The results show that attack angles play an important role in the performance of square column VIVPEH, of which α=45° is a relatively ideal attack angle of square column VIVPEH.

General theory of detection of signal induced in vibrating magnetometer

International Nuclear Information System (INIS)

Pacyna, A.W.

1980-01-01

Assuming the point dipole approximation only and making use of the vectorial notation, signal (EMF) induced in a single-turn pick-up coil of the vibrating magnetometer are calculated for the case of any orientation of the coil, of vibration axis and of the magnetic moment of the sample. On the basis of formula obtained, three types of measurement geometries have been distinquished and for these the qualitative analysis is made. (author)

Intelligent control for braking-induced longitudinal vibration responses of floating-type railway bridges

Science.gov (United States)

Qu, Wei-Lian; Qin, Shun-Quan; Tu, Jian-Weia; Liu, Jia; Zhou, Qiang; Cheng, Haibin; Pi, Yong-Lin

2009-12-01

This paper presents an intelligent control method and its engineering application in the control of braking-induced longitudinal vibration of floating-type railway bridges. Equations of motion for the controlled floating-type railway bridges have been established based on the analysis of the longitudinal vibration responses of floating-type railway bridges to train braking and axle-loads of moving trains. For engineering applications of the developed theory, a full-scale 500 kN smart magnetorheologic (MR) damper has been designed, fabricated and used to carry out experiments on the intelligent control of braking-induced longitudinal vibration. The procedure for using the developed intelligent method in conjunction with the full-scale 500 kN MR dampers has been proposed and used to control the longitudinal vibration responses of the deck of floating-type railway bridges induced by train braking and axle-loads of moving trains. This procedure has been applied to the longitudinal vibration control of the Tian Xingzhou highway and railway cable-stayed bridge over the Yangtze River in China. The simulated results have shown that the intelligent control system using the smart MR dampers can effectively control the longitudinal response of the floating-type railway bridge under excitations of braking and axle-loads of moving trains.

Intelligent control for braking-induced longitudinal vibration responses of floating-type railway bridges

International Nuclear Information System (INIS)

Qu, Wei-Lian; Tu, Jian-Weia; Liu, Jia; Zhou, Qiang; Qin, Shun-Quan; Cheng, Haibin; Pi, Yong-Lin

2009-01-01

This paper presents an intelligent control method and its engineering application in the control of braking-induced longitudinal vibration of floating-type railway bridges. Equations of motion for the controlled floating-type railway bridges have been established based on the analysis of the longitudinal vibration responses of floating-type railway bridges to train braking and axle-loads of moving trains. For engineering applications of the developed theory, a full-scale 500 kN smart magnetorheologic (MR) damper has been designed, fabricated and used to carry out experiments on the intelligent control of braking-induced longitudinal vibration. The procedure for using the developed intelligent method in conjunction with the full-scale 500 kN MR dampers has been proposed and used to control the longitudinal vibration responses of the deck of floating-type railway bridges induced by train braking and axle-loads of moving trains. This procedure has been applied to the longitudinal vibration control of the Tian Xingzhou highway and railway cable-stayed bridge over the Yangtze River in China. The simulated results have shown that the intelligent control system using the smart MR dampers can effectively control the longitudinal response of the floating-type railway bridge under excitations of braking and axle-loads of moving trains

MEMS Device Being Developed for Active Cooling and Temperature Control

Science.gov (United States)

Moran, Matthew E.

2001-01-01

High-capacity cooling options remain limited for many small-scale applications such as microelectronic components, miniature sensors, and microsystems. A microelectromechanical system (MEMS) is currently under development at the NASA Glenn Research Center to meet this need. It uses a thermodynamic cycle to provide cooling or heating directly to a thermally loaded surface. The device can be used strictly in the cooling mode, or it can be switched between cooling and heating modes in milliseconds for precise temperature control. Fabrication and assembly are accomplished by wet etching and wafer bonding techniques routinely used in the semiconductor processing industry. Benefits of the MEMS cooler include scalability to fractions of a millimeter, modularity for increased capacity and staging to low temperatures, simple interfaces and limited failure modes, and minimal induced vibration.

A new methodology for predicting flow induced vibration in industrial components

International Nuclear Information System (INIS)

Gay, N.

1997-12-01

Flow induced vibration damage is a major concern for designers and operators of industrial components. For example, nuclear power plant operators have currently to deal with such flow induced vibration problems, in steam generator tube bundles, control rods or nuclear fuel assemblies. Some methodologies have thus been recently proposed to obtain an accurate description of the flow induced vibration phenomena. These methodologies are based on unsteady semi-analytical models for fluid-dynamic forces, associated with non-dimensional fluid force coefficients generally obtained from experiments. The aim is to determine the forces induced by the flow on the structure, and then to take account of these forces to derive the dynamic behaviour of the component under flow excitation. The approach is based on a general model for fluid-dynamic forces, using several non-dimensional parameters that cannot be reached through computation. These parameters are then determined experimentally on simplified test sections, representative of the component, of the flow and of the fluid-elastic coupling phenomena. Predicting computations of the industrial component can then be performed for various operating configurations, by applying laws of similarity. The major physical mechanisms involved in complex fluid-structure interaction phenomena have been understood and modelled. (author)

Experimental investigation of railway train-induced vibrations of surrounding ground and a nearby multi-story building

Science.gov (United States)

Xia, He; Chen, Jianguo; Wei, Pengbo; Xia, Chaoyi; de Roeck, G.; Degrande, G.

2009-03-01

In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing-Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration (FTA) criteria for acceptable ground-borne vibrations expressed in terms of rms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.

Effect of angle on flow-induced vibrations of pinniped vibrissae.

Directory of Open Access Journals (Sweden)

Christin T Murphy

Full Text Available Two types of vibrissal surface structures, undulated and smooth, exist among pinnipeds. Most Phocidae have vibrissae with undulated surfaces, while Otariidae, Odobenidae, and a few phocid species possess vibrissae with smooth surfaces. Variations in cross-sectional profile and orientation of the vibrissae also exist between pinniped species. These factors may influence the way that the vibrissae behave when exposed to water flow. This study investigated the effect that vibrissal surface structure and orientation have on flow-induced vibrations of pinniped vibrissae. Laser vibrometry was used to record vibrations along the whisker shaft from the undulated vibrissae of harbor seals (Phoca vitulina and northern elephant seals (Mirounga angustirostris and the smooth vibrissae of California sea lions (Zalophus californianus. Vibrations along the whisker shaft were measured in a flume tank, at three orientations (0°, 45°, 90° to the water flow. The results show that vibration frequency and velocity ranges were similar for both undulated and smooth vibrissae. Angle of orientation, rather than surface structure, had the greatest effect on flow-induced vibrations. Vibration velocity was up to 60 times higher when the wide, flat aspect of the whisker faced into the flow (90°, compared to when the thin edge faced into the flow (0°. Vibration frequency was also dependent on angle of orientation. Peak frequencies were measured up to 270 Hz and were highest at the 0° orientation for all whiskers. Furthermore, CT scanning was used to quantify the three-dimensional structure of pinniped vibrissae that may influence flow interactions. The CT data provide evidence that all vibrissae are flattened in cross-section to some extent and that differences exist in the orientation of this profile with respect to the major curvature of the hair shaft. These data support the hypothesis that a compressed cross-sectional profile may play a key role in reducing self

The meninges contribute to the conditioned taste avoidance induced by neural cooling in male rats.

Science.gov (United States)

Wang, Yuan; Chambers, Kathleen C

2002-08-21

After consumption of a novel sucrose solution, temporary cooling of neural areas that mediate conditioned taste avoidance can itself induce conditioned avoidance to the sucrose. It has been suggested that this effect is either a result of inactivation of neurons in these areas or of cooling the meninges. In a series of studies, we demonstrated that cooling the outer layer of the meninges, the dura mater, does not contribute to the conditioned taste avoidance induced by cooling any of these areas. The present experiments were designed to determine whether the inner layers of the meninges are involved. If they are involved, then one would expect that cooling locations in the brain that do not mediate conditioned taste avoidance, such as the caudate putamen (CP), would induce conditioned taste avoidance as long as the meninges were cooled as well. One also would expect that cooling neural tissue without cooling the meninges would reduce the strength of the conditioned taste avoidance. Experiment 1 established that the temperature of the neural tissue and meninges around the cold probes implanted in the CP were cooled to temperatures that have been shown to block synaptic transmission. Experiment 2 demonstrated that cooling the caudate putamen and overlying cortex and meninges induced conditioned taste avoidance. In experiment 3, a circle of meninges was cut away so that the caudate putamen and overlying cortex could be cooled without cooling the meninges. The strength of the conditioned taste avoidance was substantially reduced, but it was not entirely eliminated. These data support the hypothesis that cooling the meninges contributes to the conditioned taste avoidance induced by neural cooling. They also allow the possibility that neural inactivation produces physiological changes that can induce conditioned taste avoidance. Copyright 2002 Elsevier Science B.V.

Vibration damping method and apparatus

Science.gov (United States)

Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.

1999-01-01

The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.

Fast reactor flow induced vibration with particular reference to PFR and conceptual CDFR design

Energy Technology Data Exchange (ETDEWEB)

Collinson, A E [REML, UKAEA, RNPDE, Risley, Warrington (United Kingdom)

1977-12-01

This paper describes development work and basic design criteria as applied to vibration induced by fluid flow for the United Kingdom LMFBR programme. Possible harmful effects that could result from excessive vibration levels are highlighted with the associated excitation mechanisms. Instances of flow-induced vibration encountered in development models and in PFR are described. Basic design requirements and the overall philosophy are considered with respect to PFR and notional CDFRs. Ongoing research objectives are outlined giving some insight into the broad strategy involved. Finally, details are given concerning projects presently in progress along with more long term proposals. (author)

Fast reactor flow induced vibration with particular reference to PFR and conceptual CDFR design

International Nuclear Information System (INIS)

Collinson, A.E.

1977-01-01

This paper describes development work and basic design criteria as applied to vibration induced by fluid flow for the United Kingdom LMFBR programme. Possible harmful effects that could result from excessive vibration levels are highlighted with the associated excitation mechanisms. Instances of flow-induced vibration encountered in development models and in PFR are described. Basic design requirements and the overall philosophy are considered with respect to PFR and notional CDFRs. Ongoing research objectives are outlined giving some insight into the broad strategy involved. Finally, details are given concerning projects presently in progress along with more long term proposals. (author)

Studies on flow induced vibration of reactivity devices of 700 MWe Indian PHWR

Energy Technology Data Exchange (ETDEWEB)

Prabhakaran, K.M., E-mail: kmprabha@yahoo.com [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Goyal, P.; Dutta, Anu; Bhasin, V.; Vaze, K.K.; Ghosh, A.K. [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Pillai, Ajith V.; Mathew, Jimmy [Nuclear Power Corporation of India Ltd., Mumbai 400 094 (India)

2012-03-15

Highlights: Black-Right-Pointing-Pointer FIV studies on internals of heavy water filled calandria of 700 MWe Indian PHWR is presented. Black-Right-Pointing-Pointer This includes CFD and structural dynamic analysis to predict the dynamic behavior of component lying inside calandria. Black-Right-Pointing-Pointer Results of these calculations as well as conclusions from this investigation are presented. Black-Right-Pointing-Pointer It is established that FIV is not a concern in the present design of calandria internals. - Abstract: Component failures due to excessive flow-induced vibration are still affecting the performance and reliability of nuclear power stations. Tube failures due to fretting-wear in nuclear steam generators, and vibration related damage of reactor internals are of particular concern. In the Indian nuclear industry, flow induced vibrations are assessed early in the design process and the results are incorporated in the design procedures. In this paper the details of flow induced vibration studies on internals like liquid zone control unit and poison injection units of heavy water filled calandria of 700 MWe Indian pressurized heavy water reactor is given. This includes computational fluid dynamics studies from which the velocities are extracted for the components lying inside the calandria. With these velocities as input, further studies are performed to predict the dynamic behavior of these components. Results of these calculations as well as conclusions derived from this investigation are presented. Based on the studies it has been established that flow induced vibration is not a concern in the present design of 700 MWe calandria internals.

Neuropathic Pain-like Alterations in Muscle Nociceptor Function Associated with Vibration-induced Muscle Pain

OpenAIRE

Chen, Xiaojie; Green, Paul G.; Levine, Jon D.

2010-01-01

We recently developed a rodent model of the painful muscle disorders induced by occupational exposure to vibration. In the present study we used this model to evaluate the function of sensory neurons innervating the vibration-exposed gastrocnemius muscle. Activity of 74 vibration-exposed and 40 control nociceptors, with mechanical receptive fields in the gastrocnemius muscle, were recorded. In vibration-exposed rats ~15% of nociceptors demonstrated an intense and long-lasting barrage of actio...

Flow induced vibration of the large-sized sodium valve for MONJU

Energy Technology Data Exchange (ETDEWEB)

Sato, K [Sodium Engineering Division, O-arai Engineering Centre, Power Reactor and Nuclear Fuel Development Corporation, Nariata-cho, O-arai Machi, Ibaraki-ken (Japan)

1977-12-01

Measurements have been made on the hydraulic characteristics of the large-sized sodium valves in the hydraulic simulation test loop with water as fluid. The following three prototype sodium valves were tested; (1) 22-inch wedge gate type isolation valve, (2) 22-inch butterfly type isolation valve, and (3) 16-inch butterfly type control valve. In the test, accelerations of flow induced vibrations were measured as a function of flow velocity and disk position. The excitation mechanism of the vibrations is not fully interpreted in these tests due to the complexity of the phenomena, but the experimental results suggest that it closely depends on random pressure fluctuations near the valve disk and flow separation at the contracted cross section between the valve seat and the disk. The intensity of flow induced vibrations suddenly increases at a certain critical condition, which depends on the type of valve and is proportional to fluid velocity. (author)

Flow induced vibration of the large-sized sodium valve for MONJU

International Nuclear Information System (INIS)

Sato, K.

1977-01-01

Measurements have been made on the hydraulic characteristics of the large-sized sodium valves in the hydraulic simulation test loop with water as fluid. The following three prototype sodium valves were tested; (1) 22-inch wedge gate type isolation valve, (2) 22-inch butterfly type isolation valve, and (3) 16-inch butterfly type control valve. In the test, accelerations of flow induced vibrations were measured as a function of flow velocity and disk position. The excitation mechanism of the vibrations is not fully interpreted in these tests due to the complexity of the phenomena, but the experimental results suggest that it closely depends on random pressure fluctuations near the valve disk and flow separation at the contracted cross section between the valve seat and the disk. The intensity of flow induced vibrations suddenly increases at a certain critical condition, which depends on the type of valve and is proportional to fluid velocity. (author)

Flow induced vibrations of piping

International Nuclear Information System (INIS)

Gibert, R.J.; Axisa, F.

1977-01-01

In order to design the supports of piping systems, estimations of the vibrations induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary to calculate the model parameters of liquid containing pipes. In most computer codes, fluid effects are accounted for just by adding the fluid mass to the structure. This may lead to serious errors. This paper presents a method to take into account these effects, by solving a coupled mechanical-acoustical problem: the computer code TEDEL of the C.E.A /D.E.M.T. System, based on the finite-elements method, has been extended to calculate simultaneously the pressure fluctuations in the fluid and the vibrations of the pipe. By this way the mechanical-acoustical coupled eigenmodes of any piping system can be obtained. These eigenmodes are used to determine the response of the system to various sources. Equations have been written in the hypohesis that acoustical wave lengths remain large compared to the diameter of the pipe. The method has been checked by an experiment performed on the GASCOGNE loop at D.E.M.T. The piping system under test consists of a tube with four elbows. The circuit is ended at each extremity by a large vessel which performs acoustical isolation by generating modes for the pressure. Excitation of the circuit is caused by a valve located near the downstream vessel. This provides an efficient localised broad band acoustical source. The comparison between the test results and the calculations has shown that the low frequency resonant characteristics of the pipe and the vibrational amplitude at various flow-rates can be correctly predicted

Flow Induced Vibration Program at Argonne National Laboratory

International Nuclear Information System (INIS)

1984-01-01

Argonne National Laboratory has had a Flow Induced Vibration Program since 1967; the Program currently resides in the Laboratory's Components Technology Division. Throughout its existence, the overall objective of the program has been to develop and apply new and/or improved methods of analysis and testing for the design evaluation of nuclear reactor plant components and heat exchange equipment from the standpoint of flow induced vibration. Historically, the majority of the program activities have been funded by the US Atomic Energy Commission (AEC), Energy Research and Development Administration (ERDA), and Department of Energy (DOE). Current DOE funding is from the Breeder Mechanical Component Development Division, Office of Breeder Technology Projects; Energy Conversion and Utilization Technology (ECUT) Program, Office of Energy Systems Research; and Division of Engineering, Mathematical and Geosciences, Office of Basic Energy Sciences. Testing of Clinch River Breeder Reactor upper plenum components has been funded by the Clinch River Breeder Reactor Plant (CRBRP) Project Office. Work has also been performed under contract with Foster Wheeler, General Electric, Duke Power Company, US Nuclear Regulatory Commission, and Westinghouse

A Study on the Uncertainty of Flow-Induced Vibration in a Cross Flow over Staggered Tubes

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji-Su; Park, Jong-Woon [Dongguk univ, Gyeong Ju (Korea, Republic of); Choi, Hyeon-Kyeong [HanNam University, Daejeon (Korea, Republic of)

2015-05-15

Cross-flow in many support columns of very high temperature reactor (VHTR) lower plenum would have FIV issues under high speed flow jetting from the core. For a group of multiple circular cylinders subjected to a cross-flow, three types of potential vibration mechanisms may exist: (1) Vortex-induced vibration (VIV), (2) Fluid-elastic vibration (FEV) and (3) Turbulence-induced vibration (TIV). Kevalahan studied the free vibration of circular cylinders in a tightly packed periodic square inline array of cylinders. Pandey et al. studied the flue gas flow distribution in the Low Temperature Super Heater (LTSH) tube bundles situated in second pass of a utility boiler and the phenomenon of flow induced vibration. Nakamura et al. studied flow instability of cylinder arrays resembling U-bend tubes in steam generators. The FIV evaluation is usually performed with computational fluid dynamic (CFD) analysis to obtain unknown frequency of oscillation of the multiple objects under turbulent flow and thus the uncertainty residing in the turbulence model used should be quantified. In this paper, potential FIV uncertainty arising from the turbulence phenomena are evaluated for a typical cross flow through staggered tube bundles resembling the VHTR lower plenum support columns. Flow induced vibration (FIV) is one of the important mechanical and fatigue issues in nuclear systems. Especially, cross-flow in many support structures of VHTR lower plenum would have FIV issues under highly turbulent jet flows from the core. The results show that the effect of turbulence parameters on FIV is not negligible and the uncertainty is 5 to 10%. Present method can be applied to future FIV evaluations of nuclear systems. More extensive studies on flow induced vibration in a plant scale by using more rigorous computational methods are under way.

Vibration-free stirling cryocooler for high definition microscopy

Science.gov (United States)

Riabzev, S. V.; Veprik, A. M.; Vilenchik, H. S.; Pundak, N.; Castiel, E.

2009-12-01

The normal operation of high definition Scanning Electronic and Helium Ion microscope tools often relies on maintaining particular components at cryogenic temperatures. This has traditionally been accomplished by using liquid coolants such as liquid Nitrogen. This inherently limits the useful temperature range to above 77 K, produces various operational hazards and typically involves elevated ownership costs, inconvenient logistics and maintenance. Mechanical coolers, over-performing the above traditional method and capable of delivering required (even below 77 K) cooling to the above cooled components, have been well-known elsewhere for many years, but their typical drawbacks, such as high purchasing cost, cooler size, low reliability and high power consumption have so far prevented their wide-spreading. Additional critical drawback is inevitable degradation of imagery performance originated from the wideband vibration export as typical for the operation of the mechanical cooler incorporating numerous movable components. Recent advances in the development of reliable, compact, reasonably priced and dynamically quiet linear cryogenic coolers gave rise to so-called "dry cooling" technologies aimed at eventually replacing the traditional use of outdated liquid Nitrogen cooling facilities. Although much improved these newer cryogenic coolers still produce relatively high vibration export which makes them incompatible with modern high definition microscopy tools. This has motivated further research activity towards developing a vibration free closed-cycle mechanical cryocooler. The authors have successfully adapted the standard low vibration Stirling cryogenic refrigerator (Ricor model K535-LV) delivering 5 W@40 K heat lift for use in vibration-sensitive high definition microscopy. This has been achieved by using passive mechanical counterbalancing of the main portion of the low frequency vibration export in combination with an active feed-forward multi

Predicting vibration-induced displacement for a resonant friction slider

DEFF Research Database (Denmark)

Fidlin, A.; Thomsen, Jon Juel

2001-01-01

A mathematical model is set up to quantify vibration-induced motions of a slider, sandwiched between friction layers with different coefficients of friction, and equipped with an imbedded resonator that oscillates at high frequency and small amplitude. This model is highly nonlinear, involving non...

Preliminary Study on the Fretting Wear Behaviors of a Duel Cooled Fuel Rod

Energy Technology Data Exchange (ETDEWEB)

Lee, Y.H.; Lee, K.H.; Kim, H.K. [KAERI, 150 Dukjin-dong Yuseon-gu Daejeon, 305-353 (Korea, Republic of)

2009-06-15

Based on MIT's concept, an innovative fuel development project was launched by KAERI that a substantial power up-rating could be realized by introducing an internally and externally double cooled annular fuel for current PWR reactors. In order to apply this duel cooled fuel to an OPR 1000 reactor system, geometrical features of structural parts in a fuel assembly should be changed except an overall dimension of a fuel assembly. Typical changes are summarized as fuel rod diameter and weight, shape and position of a spacer grid spring, etc. When considering a duel cooled fuel rod, its vibration characteristic and fretting behavior should be verified because the modified shape and dimension of spacer grid spring, fuel rod diameter and weight, number of spacer grid assembly are closely related to a flow-induced vibration in a duel cooled fuel assembly. In this study, based on FIV test results of 4x4 fuel assembly, fretting wear tests of an outer duel cooled fuel rod were performed by using an embossing type spacer grid spring that could adjust its spring stiffness. The discussion was focused on the evaluation of the optimized spring stiffness and spring position in 1x1 cell by analyzing the fretting wear results. (authors)

Experimental chaotic quantification in bistable vortex induced vibration systems

Science.gov (United States)

Huynh, B. H.; Tjahjowidodo, T.

2017-02-01

The study of energy harvesting by means of vortex induced vibration systems has been initiated a few years ago and it is considered to be potential as a low water current energy source. The energy harvester is realized by exposing an elastically supported blunt structure under water flow. However, it is realized that the system will only perform at a limited operating range (water flow) that is attributed to the resonance phenomenon that occurs only at a frequency that corresponds to the fluid flow. An introduction of nonlinear elements seems to be a prominent solution to overcome the problem. Among many nonlinear elements, a bistable spring is known to be able to improve the harvested power by a vortex induced vibrations (VIV) based energy converter at the low velocity water flows. However, it is also observed that chaotic vibrations will occur at different operating ranges that will erratically diminish the harvested power and cause a difficulty in controlling the system that is due to the unpredictability in motions of the VIV structure. In order to design a bistable VIV energy converter with improved harvested power and minimum negative effect of chaotic vibrations, the bifurcation map of the system for varying governing parameters is highly on demand. In this study, chaotic vibrations of a VIV energy converter enhanced by a bistable stiffness element are quantified in a wide range of the governing parameters, i.e. damping and bistable gap. Chaotic vibrations of the bistable VIV energy converter are simulated by utilization of a wake oscillator model and quantified based on the calculation of the Lyapunov exponent. Ultimately, a series of experiments of the system in a water tunnel, facilitated by a computer-based force-feedback testing platform, is carried out to validate the existence of chaotic responses. The main challenge in dealing with experimental data is in distinguishing chaotic response from noise-contaminated periodic responses as noise will smear

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

Directory of Open Access Journals (Sweden)

Rasmus Bjerregaard Christensen

2016-01-01

Full Text Available We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces.

Acoustical environment of gas-cooled nuclear reactors

International Nuclear Information System (INIS)

Blevins, R.D.

1986-01-01

Methods for acoustical analysis of gas-cooled nuclear reactors in terms of the sources of sound, the propagation of sound about the coolant circuit and the response of reactor structures to sound, are described. Sources of sound that are considered are circulators, jets, vortex shedding and separated flow. Circulators are generally the dominant source of sound. At low frequency the sound propagates one dimensionally through the ducts and cavities of the reactor. At high frequency the sound excites closely spaced two- and three-dimensional acoustic modes, and the resultant sound field can be described only statistically. The sound excites plate and shell structures within the coolant circuit. Secondary steam piping can also be excited by pumps and valves. Formulations are presented for the resultant vibration. Vibration-induced damage is also reviewed. (author)

Mechanisms Mediating Vibration-induced Chronic Musculoskeletal Pain Analyzed in the Rat

OpenAIRE

Dina, Olayinka A.; Joseph, Elizabeth K.; Levine, Jon D.; Green, Paul G.

2009-01-01

While occupational exposure to vibration is a common cause of acute and chronic musculoskeletal pain, eliminating exposure produces limited symptomatic improvement, and re-exposure precipitates rapid recurrence or exacerbation. To evaluate mechanisms underlying these pain syndromes, we have developed a model in the rat, in which exposure to vibration (60–80 Hz) induces, in skeletal muscle, both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia t...

A modified wake oscillator model for predicting vortex induced vibration of heat exchanger tube

International Nuclear Information System (INIS)

Feng Zhipeng; Zang Fenggang; Zhang Yixiong; Ye Xianhui

2014-01-01

Base on the classical wake oscillator model, a new modified wake oscillator model is proposed, for predicting vortex induced vibration of heat exchanger tube in uniform current. The comparison between the new wake oscillator model and experimental show that the present model can simulate the characteristics of vortex induced vibration of tube. Firstly, the research shows that the coupled fluid-structure dynamical system should be modeled by combined displacement and acceleration mode. Secondly, the empirical parameter in wake oscillator model depends on the material properties of the structure, instead of being a universal constant. Lastly, the results are compared between modified wake oscillator model and fluid-structure interaction numerical model. It shows the present, predicted results are compared to the fluid-structure interaction numerical data. The new modified wake oscillator model can predict the vortex induced heat exchanger tube vibration feasibly. (authors)

Fluid dynamic forces acting on a circular tube bundle in cross flow. Proposals of generation condition of vortex-induced vibration and correlation equation of turbulence-induced exciting force

International Nuclear Information System (INIS)

Inada, Fumio; Yoneda, Kimitoshi; Yasuo, Akira; Nishihara, Takashi

2000-01-01

In the circular tube bundle immersed in the crossflow, the exciting force induced by the turbulence and periodically discharged vortices becomes large, and it is necessary to confirm a long-term integrity to the flow induced vibration. In this report, the local fluid exciting force and the correlation length in the direction of tube axis were measured. The exciting force acting on the first row was smaller than that inside the tube bundle, and the exciting force was almost saturated at the third row. As for vortex induced vibration, there could be an influence when a dimensionless frequency was 0.4 or less. When vortex induced vibration did not affect the vibration, a correlation composed of a correlation length and power spectrum density of the local fluid exciting force were proposed, with which we could estimate the amplitude of the vibration. A computer program to estimate the vibration amplitude and maximum stress was made using the flow velocity distribution and the mode of vibration. (author)

Mathematical model for cross-flow-induced vibrations of tube rows

International Nuclear Information System (INIS)

Chen, S.S.

1976-09-01

A mathematical model for flow-induced vibrations in heat exchanger tube banks is presented which includes the effects of vortex shedding, fluidelastic coupling, drag force, and fluid inertia coupling. Once the fluid forces are known, the model can predict the details of complex tube-fluid interactions: (1) natural frequencies and mode shapes of coupled vibrations; (2) critical flow velocities; (3) responses to vortex shedding, drag force, and other types of excitations; and (4) the dominant excitation mechanism at a given flow velocity. The analytical results are in good agreement with the published experimental results

Analysis of flow-induced vibrations in the PEC design

International Nuclear Information System (INIS)

Cornaggia, L.; Reale, M.; Martelli, A.; Zambelli, M.

1986-01-01

This paper summarizes the studies performed for the Italian PEC fast reactor test facility with regard to flow-induced vibration problems. Reference is made to the reactor-block, the primary and secondary coolant loops and the emergency loops. Studies in progress and future developments foreseen are also mentioned. (author)

Numerical Simulation of Airfoil Vibrations Induced by Turbulent Flow

Czech Academy of Sciences Publication Activity Database

Feistauer, M.; Horáček, Jaromír; Sváček, P.

2015-01-01

Roč. 17, č. 1 (2015), s. 146-188 ISSN 1815-2406 R&D Projects: GA ČR(CZ) GAP101/11/0207 Institutional support: RVO:61388998 Keywords : fluid-structure interaction * flow induced vibrations * turbulence models * finite element method Subject RIV: BI - Acoustics Impact factor: 1.778, year: 2015

Probabilistic analysis of wind-induced vibration mitigation of structures by fluid viscous dampers

Science.gov (United States)

Chen, Jianbing; Zeng, Xiaoshu; Peng, Yongbo

2017-11-01

The high-rise buildings usually suffer from excessively large wind-induced vibrations, and thus vibration control systems might be necessary. Fluid viscous dampers (FVDs) with nonlinear power law against velocity are widely employed. With the transition of design method from traditional frequency domain approaches to more refined direct time domain approaches, the difficulty of time integration of these systems occurs sometimes. In the present paper, firstly the underlying reason of the difficulty is revealed by identifying that the equations of motion of high-rise buildings installed with FVDs are sometimes stiff differential equations. Thus, an approach effective for stiff differential systems, i.e., the backward difference formula (BDF), is then introduced, and verified to be effective for the equation of motion of wind-induced vibration controlled systems. Comparative studies are performed among some methods, including the Newmark method, KR-alpha method, energy-based linearization method and the statistical linearization method. Based on the above results, a 20-story steel frame structure is taken as a practical example. Particularly, the randomness of structural parameters and of wind loading input is emphasized. The extreme values of the responses are examined, showing the effectiveness of the proposed approach, and also necessitating the refined probabilistic analysis in the design of wind-induced vibration mitigation systems.

Evaluation of the Perceptual Characteristics of a Force Induced by Asymmetric Vibrations.

Science.gov (United States)

Tanabe, Takeshi; Yano, Hiroaki; Iwata, Hiroo

2017-08-29

This paper describes the properties of proprioceptive sensations induced by asymmetric vibration using a vibration speaker-type non-grounded haptic interface. We confirm that the vibration speaker generates a perceived force that pulls or pushes a user's hand in a particular direction when an asymmetric amplitude signal that is generated by inverting a part of a sine wave is input. In this paper, to verify the system with respect to various factors of force perception caused by asymmetric vibration, we conducted six experiments and the following results were obtained. (1) The force vector can be controlled by reversing the asymmetric waves. (2) By investigating the physical characteristics of the vibration, asymmetric vibration was confirmed. (3) The presentation of vibration in the shear direction on the finger pad is effective. (4) The point of subjective equality of the perceived force can be controlled by up to 0.43 N by changing the amplitude voltage of the input signals. (5) The minimum stimulation time required for force perception is 66.7 ms. (6) When the vibration is continuously presented for 40 to 50 s, the perceived force decreases because of adaptation. Hence, we confirmed that we can control both the direction and magnitude of the reaction force by changing the input signal of the vibration speaker.

Numerical investigation on vibration and noise induced by unsteady flow in an axial-flow pump

Energy Technology Data Exchange (ETDEWEB)

Chen, Eryun; Ma, Zui Ling; Yang, Ai Ling; Nan, Guo Fang [School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai (China); Zhao, Gai Ping [School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai (China); Li, Guo Ping [Shanghai Marine Equipment Research Institute, Shanghai (China)

2016-12-15

Full-scale structural vibration and noise induced by flow in an axial-flow pump was simulated by a hybrid numerical method. An unsteady flow field was solved by a large eddy simulation-based computational fluid dynamics commercial code, Fluent. An experimental validation on pressure fluctuations was performed to impose an appropriate vibration exciting source. The consistency between the computed results and experimental tests were interesting. The modes of the axial-flow pump were computed by the finite element method. After that, the pump vibration and sound field were solved using a coupled vibro-acoustic model. The numerical results indicated that the the blade-passing frequency was the dominant frequency of the vibration acceleration of the pump. This result was consistent with frequency spectral characteristics of unsteady pressure fluctuation. Finally, comparisons of the vibration acceleration between the computed results and the experimental test were conducted. These comparisons validated the computed results. This study shows that using the hybrid numerical method to evaluate the flow-induced vibration and noise generated in an axial-flow pump is feasible.

Stabilization of axisymmetric liquid bridges through vibration-induced pressure fields.

Science.gov (United States)

Haynes, M; Vega, E J; Herrada, M A; Benilov, E S; Montanero, J M

2018-03-01

Previous theoretical studies have indicated that liquid bridges close to the Plateau-Rayleigh instability limit can be stabilized when the upper supporting disk vibrates at a very high frequency and with a very small amplitude. The major effect of the vibration-induced pressure field is to straighten the liquid bridge free surface to compensate for the deformation caused by gravity. As a consequence, the apparent Bond number decreases and the maximum liquid bridge length increases. In this paper, we show experimentally that this procedure can be used to stabilize millimeter liquid bridges in air under normal gravity conditions. The breakup of vibrated liquid bridges is examined experimentally and compared with that produced in absence of vibration. In addition, we analyze numerically the dynamics of axisymmetric liquid bridges far from the Plateau-Rayleigh instability limit by solving the Navier-Stokes equations. We calculate the eigenfrequencies characterizing the linear oscillation modes of vibrated liquid bridges, and determine their stability limits. The breakup process of a vibrated liquid bridge at that stability limit is simulated too. We find qualitative agreement between the numerical predictions for both the stability limits and the breakup process and their experimental counterparts. Finally, we show the applicability of our technique to control the amount of liquid transferred between two solid surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

FFTF scale-model characterization of flow-induced vibrational response of reactor internals

International Nuclear Information System (INIS)

Ryan, J.A.; Julyk, L.J.

1977-01-01

As an integral part of the Fast Test Reactor Vibration Program for Reactor Internals, the flow-induced vibrational characteristics of scaled Fast Test Reactor core internal and peripheral components were assessed under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup. The Hydraulic Core Mockup, a 0.285 geometric scale model, was designed to model the vibrational and hydraulic characteristics of the Fast Test Reactor. Model component vibrational characteristics were measured and determined over a range of 36 percent to 111 percent of the scaled prototype design flow. Selected model and prototype components were shaker tested to establish modal characteristics. The dynamic response of the Hydraulic Core Mockup components exhibited no anomalous flow-rate dependent or modal characteristics, and prototype response predictions were adjudged acceptable

FFTF scale-model characterization of flow induced vibrational response of reactor internals

Energy Technology Data Exchange (ETDEWEB)

Ryan, J A; Julyk, L J [Hanford Engineering Development Laboratory, Richland, WA (United States)

1977-12-01

As an integral part of the Fast Test Reactor Vibration Program for Reactor Internals, the flow-induced vibrational characteristics of scaled Fast Test Reactor core internal and peripheral components were assessed under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup. The Hydraulic Core Mockup, a 0.285 geometric scale model, was designed to model the vibrational and hydraulic characteristics of the Fast Test Reactor. Model component vibrational characteristics were measured and determined over a range of 36% to 111% of the scaled prototype design flow. Selected model and prototype components were shaker tested to establish modal characteristics. The dynamic response of the Hydraulic Core Mockup components exhibited no anomalous flow-rate dependent or modal characteristics, and prototype response predictions were adjudged acceptable. (author)

FFTF scale-model characterization of flow induced vibrational response of reactor internals

International Nuclear Information System (INIS)

Ryan, J.A.; Julyk, L.J.

1977-01-01

As an integral part of the Fast Test Reactor Vibration Program for Reactor Internals, the flow-induced vibrational characteristics of scaled Fast Test Reactor core internal and peripheral components were assessed under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup. The Hydraulic Core Mockup, a 0.285 geometric scale model, was designed to model the vibrational and hydraulic characteristics of the Fast Test Reactor. Model component vibrational characteristics were measured and determined over a range of 36% to 111% of the scaled prototype design flow. Selected model and prototype components were shaker tested to establish modal characteristics. The dynamic response of the Hydraulic Core Mockup components exhibited no anomalous flow-rate dependent or modal characteristics, and prototype response predictions were adjudged acceptable. (author)

The effect of mechanical vibration on orthodontically induced root resorption.

Science.gov (United States)

Yadav, Sumit; Dobie, Thomas; Assefnia, Amir; Kalajzic, Zana; Nanda, Ravindra

2016-09-01

To investigate the effect of low-frequency mechanical vibration (LFMV) on orthodontically induced root resorption. Forty male CD1, 12-week-old mice were used for the study. The mice were randomly divided into five groups: group 1 (baseline)-no spring and no mechanical vibration, group 2-orthodontic spring but no vibration, group 3-orthodontic spring and 5 Hz of vibration applied to the maxillary first molar, group 4-orthodontic spring and 10 Hz of vibration applied to maxillary first molar, and group 5-orthodontic spring and 20 Hz of vibration applied to maxillary first molar. In the different experimental groups, the first molar was moved mesially for 2 weeks using a nickel-titanium coil spring delivering 10 g of force. LFMVs were applied at 5 Hz, 10 Hz, and 20 Hz. Microfocus X-ray computed tomography imaging was used to analyze root resorption. Additionally, to understand the mechanism, we applied LFMV to MC3T3 cells, and gene expression analyses were done for receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG). Orthodontic tooth movement leads to decreased root volume (increased root resorption craters). Our in vivo experiments showed a trend toward increase in root volume with different frequencies of mechanical vibration. In vitro gene expression analyses showed that with 20 Hz of mechanical vibration, there was a significant decrease in RANKL and a significant increase in OPG expression. There was a trend toward decreased root resorption with different LFMVs (5 Hz, 10 Hz, and 20 Hz); however, it was not more statistically significant than the orthodontic-spring-only group.

Laser-induced vibration of a thin soap film.

Science.gov (United States)

Emile, Olivier; Emile, Janine

2014-09-21

We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free-standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be employed in an optofluidic diaphragm pump, the interfaces behaving like a vibrating membrane and the liquid in-between being the fluid to be pumped. Such a pump could then be used in delicate micro-equipment, in chips where temperature variations are detrimental and even in biological systems.

Development of Design Criteria for Fluid Induced Structural Vibrations in Steam Generators and Heat Exchangers

International Nuclear Information System (INIS)

Catton, Ivan; Dhir, Vijay K.; Alquaddoomi, O.S.; Mitra, Deepanjan; Adinolfi, Pierangelo

2004-01-01

OAK-B135 Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-induced vibration is constantly updated with new findings and improved design criteria for heat exchangers. In the nuclear industry, steam generators are often affected by this problem. However, flow-induced vibration is not limited to nuclear power plants, but to any type of heat exchanger used in many industrial applications such as chemical processing, refrigeration and air conditioning. Specifically, shell and tube type heat exchangers experience flow-induced vibration due to the high velocity flow over the tube banks. Flow-induced vibration in these heat exchangers leads to equipment breakdown and hence expensive repair and process shutdown. The goal of this research is to provide accurate measurements that can help modelers to validate their models using the measured experimental parameters and thereby develop better design criteria for avoiding fluid-elastic instability in heat exchangers. The research is divided between two primary experimental efforts, the first conducted using water alone (single phase) and the second using a mixture of air or steam and water as the working fluid (two phase). The outline of this report is as follows: After the introduction to fluid-elastic instability, the experimental apparatus constructed to conduct the experiments is described in Chapter 2 along with the measurement procedures. Chapter 3 presents results obtained on the tube array and the flow loop, as well as techniques used in data processing. The project performance is described and evaluated in Chapter 4 followed by

Advanced non-linear flow-induced vibration and fretting-wear analysis capabilities

Energy Technology Data Exchange (ETDEWEB)

Toorani, M.; Pan, L.; Li, R.; Idvorian, N. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Vincent, B.

2009-07-01

Fretting wear is a potentially significant degradation mechanism in nuclear steam generators and other shell and tube heat transfer equipment as well. This paper presents an overview of the recently developed code FIVDYNA which is used for the non-linear flow-induced vibration and fretting wear analysis for operating steam generators (OTSG and RSG) and shell-and-tube heat exchangers. FIVDYNA is a non-linear time-history Flow-Induced Vibration (FIV) analysis computer program that has been developed by Babcock and Wilcox Canada to advance the understanding of tube vibration and tube to tube-support interaction. In addition to the dynamic fluid induced forces the program takes into account other tube static forces due to axial and lateral tube preload and thermal interaction loads. The program is capable of predicting the location where the fretting wear is most likely to occur and its magnitude taking into account the support geometry including gaps. FIVDYNA uses the general purpose finite element computer code ABAQUS as its solver. Using ABAQUS gives the user the flexibility to add additional forces to the tube ranging from tube preloads and the support offsets to thermal loads. The forces currently being modeled in FIVDYNA are the random turbulence, steady drag force, fluid-elastic forces, support offset and pre-strain force (axial loads). This program models the vibration of tubes and calculates the structural dynamic characteristics, and interaction forces between the tube and the tube supports. These interaction forces are then used to calculate the work rate at the support and eventually the predicted depth of wear scar on the tube. A very good agreement is found with experiments and also other computer codes. (author)

Development of evaluation method on flow-induced vibration and corrosion of components in two-phase flow by coupled analysis. 1. Evaluation of effects of flow-induced vibration on structural material integrity

International Nuclear Information System (INIS)

Naitoh, Masanori; Uchida, Shunsuke; Koshizuka, Seiichi; Ninokata, Hisashi; Anahara, Naoki; Dosaki, Koji; Katono, Kenichi; Akiyama, Minoru; Saitoh, Hiroaki

2007-01-01

Problems in major components and structural materials in nuclear power plants have often been caused by flow induced vibration, corrosion and their overlapping effects. In order to establish safe and reliable plant operation, it is necessary to predict future problems for structural materials based on combined analyses of flow dynamics and corrosion and to mitigate them before they become serious issues for plant operation. An innovative method for flow induced vibration of structures in two phase flow by combined analyses of three dimensional flow dynamics and structures is to be introduced. (author)

Prolonged maintenance of capsaicin-induced hyperalgesia by brief daily vibration stimuli.

Science.gov (United States)

Kim, Hee Kee; Schattschneider, Jörn; Lee, Inhyung; Chung, Kyungsoon; Baron, Ralf; Chung, Jin Mo

2007-05-01

This study tests the hypothesis that central sensitization initiated by nociceptive input can be maintained by repeated brief innocuous peripheral inputs. Capsaicin was injected intradermally into the hind paw of adult rats. Three different types of daily cutaneous mechanical stimulations (vibration, soft brush, or pressure) were applied to the capsaicin-injected paw for a period of 2 weeks. Daily stimulation consisted of a 10-s stimulation repeated every 30s for 30 min. Foot withdrawal thresholds to von Frey stimuli applied to the paw were measured once a day for 4 weeks. The capsaicin-only group (control rats without daily stimulation) showed hyperalgesia lasting for 3 days. In contrast, hyperalgesia persisted for 2 weeks in the group that received vibration stimulation. Neither the soft brush nor the pressure group showed a significant difference in mechanical threshold from the control group (capsaicin only). The vibration-induced prolonged hyperalgesia was significantly reduced by systemic injection of ifenprodil, an NMDA-receptor antagonist, but it was not influenced by either an AMPA-receptor blocker or a reactive oxygen species (ROS) scavenger. Furthermore, a dorsal column lesion did not interfere with the prolongation of hyperalgesia. Data suggest that vibration-induced prolongation of hyperalgesia is mediated by spinal NMDA-receptors, and a similar mechanism may underlie some forms of chronic pain with no obvious causes, such as complex regional pain syndrome type 1 (CRPS-1).

Review of leakage-flow-induced vibrations of reactor components

International Nuclear Information System (INIS)

Mulcahy, T.M.

1983-05-01

The primary-coolant flow paths of a reactor system are usually subject to close scrutiny in a design review to identify potential flow-induced vibration sources. However, secondary-flow paths through narrow gaps in component supports, which parallel the primary-flow path, occasionally are the excitation source for significant vibrations even though the secondary-flow rates are orders of magnitude smaller than the primary-flow rate. These so-called leakage flow problems are reviewed here to identify design features and excitation sources that should be avoided. Also, design rules of thumb are formulated that can be employed to guide a design, but quantitative prediction of component response is found to require scale-model testing

Vibrational characteristics and wear of fuel rods

International Nuclear Information System (INIS)

Schmugar, K.L.

1977-01-01

Fuel rod wear, due to vibration, is a continuing concern in the design of liquid-cooled reactors. In my report, the methodology and models that are used to predict fuel rod vibrational response and vibratory wear, in a light water reactor environment, are discussed. This methodology is being followed at present in the design of Westinghouse Nuclear Fuel. Fuel rod vibrations are expressed as the normal bending modes, and sources of rod vibration are examined with special emphasis on flow-induced mechanisms in the stable flow region. In a typical Westinghouse PWR fuel assembly design, each fuel rod is supported at multiple locations along the rod axis by a square-shaped 'grid cell'. For a fuel rod /grid support system, the development of small oscillatory motions, due to fluid flow at the rod/grid interface, results in material wear. A theoretical wear mode is developed using the Archard Theory of Adhesive Wear as the basis. Without question certainty, fretting wear becomes a serious problem if it progresses to the stage where the fuel cladding is penetrated and fuel is exposed to the coolant. Westinghouse fuel is designed to minimize fretting wear by limiting the relative motion between the fuel rod and its supports. The wear producing motion between the fuel rod and its supports occurs when the vibration amplitude exceeds the slippage threshold amplitude

Vortex induced vibrations in gapped restrainted pipes

International Nuclear Information System (INIS)

Veloso, P. de A.A.; Loula, A.F.D.

1984-01-01

The vortex induced vibration problem of gapped restrained piping is solved numerically. The model proposed by Skop-Griffin is used to describe the pipe-fluid interaction. The variational formulation is obtained modeling the gapped restraints as non-linear elastic springs. The regularized problem is solved using a finite element discretization for the spatial domain. In the time domain a finite difference discretization is used for the lift coefficient equatin and a Newmark discretization for the equation of motion. (Author) [pt

A study on the flow induced vibration in two phase flow under heating and non-heating conditions

International Nuclear Information System (INIS)

Kim, Dae Hun

2007-02-01

Critical heat flux (CHF) enhancement devices, like a spacer grid with mixing vane, cause flow-induced vibration (FIV) due to turbulence made by structural resistance. CHF enhancement and FIV reduction are usually studied separately. The main purpose of this article is to investigate the relationship between CHF and FIV. Information of flow-induced vibration due to wire coil design, is experimentally presented in this study by detecting flow-induced vibration under the two-phase flow condition with wire coil inserts. CHF experiments were performed in an upward vertical annulus tube under controlled vibration conditions to determine the effect of vibration on CHF. FIV was measured in an upward vertical tube with various wire coil inserts using air-water as flow material. CHF experiments were performed at one atmosphere with mechanically controlled vibration. A quartz tube (inner diameter of 17 mm, thickness of 2mm and length of 0.72 m) was used for outer tube and a SUS-304 tube (outer diameter of 6.35 mm, thickness of 0.89 mm and length of 0.7 m) was used for the inner heater. Vibration of the heater tube with an amplitude range of 0.1 mm to 0.5 mm and a frequency range of 10 Hz to 50 Hz was carried out at a mass flux of 115 kg/m 2 s and 215 kg/m 2 s. CHF was enhanced by vibration with a maximum ratio of 16.4 %. CHF was increased with increased amplitude and quality. The CHF correlation was developed with R (coefficient of correlation) of 0.903. FIV measuring experiments were performed at one atmosphere by changing the inserted wire coil type. An acrylic tube was used for the test section with inner diameter of 25 mm, thickness of 10 mm and length of 0.5 m. Four types of wire coil, which have a thickness of between 2 mm and 3 mm and pitch length of between 25 mm and 50 mm, were used. FIV and dynamic pressure were detected in water mass flux range of 100 ∼ 3060 kg/m 2 s and air mass flux range of 5.02 ∼ 60.3 kg/m 2 s. Vibration increased along with mass flux and

Laser-induced vibrational dynamics of ozone in solid argon

DEFF Research Database (Denmark)

Hansen, Flemming Yssing; Amstrup, B.; Henriksen, Niels Engholm

1997-01-01

We consider the vibrational dynamics, induced by an intense infrared laser pulse, in an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18 and compare the dynamics in the gas phase and in solid ar on. not perturbed by argon on a time-scale of a few picoseconds and selective...

On vortex shedding and prediction of vortex-induced vibrations of circular cylinders

Energy Technology Data Exchange (ETDEWEB)

Halse, Karl Henning

1998-12-31

In offshore installations, many crucial components can be classified as slender marine structures: risers, mooring lines, umbilicals and cables, pipelines. This thesis studies the vortex shedding phenomenon and the problem of predicting vortex-induced vibrations of such structures. As the development of hydrocarbons move to deeper waters, the importance of accurately predicting the vortex-induced response has increased and so the need for proper response prediction methods is large. This work presents an extensive review of existing research publications about vortex shedding from circular cylinders and the vortex-induced vibrations of cylinders and the different numerical approaches to modelling the fluid flow. The response predictions from different methods are found to disagree, both in response shapes and in vibration amplitudes. This work presents a prediction method that uses a fully three-dimensional structural finite element model integrated with a laminar two-dimensional Navier-Stokes solution modelling the fluid flow. This solution is used to study the flow both around a fixed cylinder and in a flexibly mounted one-degree-of-freedom system. It is found that the vortex-shedding process (in the low Reynolds number regime) is well described by the computer program, and that the vortex-induced vibration of the flexibly mounted section do reflect the typical dynamic characteristics of lock-in oscillations. However, the exact behaviour of the experimental results found in the literature was not reproduced. The response of the three-dimensional structural model is larger than the expected difference between a mode shape and a flexibly mounted section. This is due to the use of independent hydrodynamic sections along the cylinder. The predicted response is not unrealistic, and the method is considered a powerful tool. 221 refs., 138 figs., 36 tabs.

On vortex shedding and prediction of vortex-induced vibrations of circular cylinders

Energy Technology Data Exchange (ETDEWEB)

Halse, Karl Henning

1997-12-31

In offshore installations, many crucial components can be classified as slender marine structures: risers, mooring lines, umbilicals and cables, pipelines. This thesis studies the vortex shedding phenomenon and the problem of predicting vortex-induced vibrations of such structures. As the development of hydrocarbons move to deeper waters, the importance of accurately predicting the vortex-induced response has increased and so the need for proper response prediction methods is large. This work presents an extensive review of existing research publications about vortex shedding from circular cylinders and the vortex-induced vibrations of cylinders and the different numerical approaches to modelling the fluid flow. The response predictions from different methods are found to disagree, both in response shapes and in vibration amplitudes. This work presents a prediction method that uses a fully three-dimensional structural finite element model integrated with a laminar two-dimensional Navier-Stokes solution modelling the fluid flow. This solution is used to study the flow both around a fixed cylinder and in a flexibly mounted one-degree-of-freedom system. It is found that the vortex-shedding process (in the low Reynolds number regime) is well described by the computer program, and that the vortex-induced vibration of the flexibly mounted section do reflect the typical dynamic characteristics of lock-in oscillations. However, the exact behaviour of the experimental results found in the literature was not reproduced. The response of the three-dimensional structural model is larger than the expected difference between a mode shape and a flexibly mounted section. This is due to the use of independent hydrodynamic sections along the cylinder. The predicted response is not unrealistic, and the method is considered a powerful tool. 221 refs., 138 figs., 36 tabs.

Clinical aspects of the hand-arm vibration syndrome. A review.

Science.gov (United States)

Pyykkö, I

1986-10-01

At present it seems likely that the different components of the hand-arm vibration syndrome, eg, vibration-induced white finger (VWF), numbing of the hands and arms, muscular fatigue, and occasionally prevalent bone degeneration, may arise independently, and therefore they should be evaluated separately. Evidence of changes caused in the autonomic nervous functions of the body by local vibration is not conclusive. The vascular history should be confirmed objectively with a cold provocation test under laboratory conditions. In individual diagnostics it is useful to record (with modern plethysmographic techniques) the recovery of digital temperature, digital blood pressure, and flow after local cooling. Vibrotactile perception measurement seems to be suitable for group diagnosis. Much of the diagnostic weight for VWF can be obtained from accurate case histories, although, for early changes, the history may be atypical. The lack of simple objective tests for evaluating the hand-arm vibration syndrome makes it difficult to, eg, confirm the history of its different components objectively and estimate the extent of the disability it causes.

Gravity Effects on the Free Vibration of a Graphite Column

International Nuclear Information System (INIS)

Ki, Dong-Ok; Kim, Jong-Bum; Park, Keun-Bae; Lee, Won-Jae

2006-01-01

The gravity effects on the free vibration of a graphite column are studied. Graphite block is a key component of a HTGR (High Temperature Gas Cooled Reactor). The major core elements, such as the fuel blocks and neutron reflector blocks, of HTTR (High Temperature Test Reactor, Japan) and GT-MHR (Gas Turbine- Modular Helium Reactor, USA) consist of stacked hexagonal graphite blocks forming a group of columns. The vibration of the columns induced by earthquakes may lead to solid impacts between graphite blocks and structural integrity problems. The study of free vibration characteristics of the graphite block column is the first step in the core internal structure dynamic analysis. Gravity force bring a negative stiffness term to the transverse vibration analysis of heavy long column structures, and results in natural frequency reductions. Generally it is not considered in the not so tall structure cases, because the gravity term makes the analysis and design complicated. Therefore it is important to check whether the gravity effect is severe or not

A study on waviness induced vibration of ball bearings based on signal coherence theory

Science.gov (United States)

Liu, Wentao; Zhang, Yun; Feng, Zhi-Jing; Zhao, Jing-Shan; Wang, Dongfeng

2014-11-01

This paper focuses on the effects of waviness on vibration of ball bearings. An experimental analysis method is developed by adopting signal coherence theory of multiple-inputs/single-output (MISO) system. The inputs are waviness excitations of the inner and outer races, and the output is vibration response of the outer ring. Waviness excitation signals are first derived from the manufacturing deviations, and found to be strongly coherent in low frequency range. Virtual input signals are then introduced by the method of orthogonalization. In both cases of vibration acceleration and speed responses, the cumulated virtual input-output coherence function verifies that the first peak region of vibration spectrum is mainly induced by the waviness excitations. In order to distinguish the contributions of the inner and outer races, coherence functions of the virtual inputs with real inputs are calculated, and the results indicate that the outer race waviness contributes more to vibration than the inner race waviness does in the example. Further, a multi-body dynamic model is constructed and employed to frequency response analyses. It is discovered that the waviness induced spectral peak frequency is close to the natural frequency of bearing.

Vibration induced hearing loss in guinea pig cochlea: expression of TNF-alpha and VEGF.

Science.gov (United States)

Zou, Jing; Pyykkö, Ilmari; Sutinen, Päivi; Toppila, Esko

2005-04-01

Transcranial vibration was applied for seven animals at a frequency of 250 Hz for 15 min, and five animals were used as normal controls to investigate cellular and molecular mechanism linked to vibration-induced hearing loss in animal model. Compound action potential (CAP) thresholds were measured by round window niche electrode. The expression of tumour necrosis factor alpha (TNF-alpha) and its receptors (TNF R1, TNF R2), vascular endothelium growth factor (VEGF) and its receptors (VEGF R1, VEGF R2) were analysed by immunohistochemistry. Transcranial vibration caused expression of TNF-alpha, TNF R1 and TNF R2 in the cochlea and the expression of TNF R2 was stronger than that of TNF R1. Vibration also induced VEGF and VEGF R2 expression in the cochlea. The average immediate hearing loss was 62 dB and after three days still 48 dB. It is concluded that transcranial vibration as during temporal bone drilling produces cochlear shear stress that is connected with up-regulation of TNF-alpha and its receptors. Also VEGF and VEGF R2 are up-regulated. These responses may be linked to both the damage and repair process of the cochlea.

Structural impact response for assessing railway vibration induced on buildings

Science.gov (United States)

Kouroussis, Georges; Mouzakis, Harris P.; Vogiatzis, Konstantinos E.

2018-03-01

Over the syears, the rapid growth in railway infrastructure has led to numerous environmental challenges. One such significant issue, particularly in urban areas, is ground-borne vibration. A common source of ground-borne vibration is caused by local defects (e.g. rail joints, switches, turnouts, etc.) that generate large amplitude excitations at isolated locations. Modelling these excitation sources is particularly challenging and requires the use of complex and extensive computational efforts. For some situations, the use of experiments and measured data offers a rapid way to estimate the effect of such defects and to evaluate the railway vibration levels using a scoping approach. In this paper, the problem of railway-induced ground vibrations is presented along with experimental studies to assess the ground vibration and ground borne noise levels, with a particular focus on the structural response of sensitive buildings. The behaviour of particular building foundations is evaluated through experimental data collected in Brussels Region, by presenting the expected frequency responses for various types of buildings, taking into account both the soil-structure interaction and the tramway track response. A second study is dedicated to the Athens metro, where transmissibility functions are used to analyse the effect of various Athenian building face to metro network trough comprehensive measurement campaigns. This allows the verification of appropriate vibration mitigation measures. These benchmark applications based on experimental results have been proved to be efficient to treat a complex problem encountered in practice in urban areas, where the urban rail network interacts with important local defects and where the rise of railway ground vibration problems has clearly been identified.

Diagnostic tests in Raynaud's phenomena in workers exposed to vibration: a comparative study

DEFF Research Database (Denmark)

Olsen, N

1988-01-01

Four objective tests to evaluate Raynaud's phenomena (RP) in workers exposed to handarm vibrations were applied on 23 exposed men with RP (vibration induced white finger 18, primary Raynaud's phenomenon 5), 56 exposed men without RP, and 15 male controls. Finger systolic blood pressure was measured...... greater than 0.20). The results indicate that a finger colour test may be as valuable as a FSP(0) test for diagnostic purposes. FSP(A) only indicates if a cold response is exaggerated and does not diagnose RP. The pressure measurements may further be of guidance in evaluating preventive measures...... by a cuff and strain gauge technique after combined body cooling and finger cooling during five minute ischaemia to 30 degrees, 15 degrees, and 6 degrees C. An attack of RP was detected as a zero pressure, FSP(0) test, whereas a pressure, reduced to a value below the normal 95% confidence limit at 6 degrees...

Study on flow-induced vibration of the fuel rod in HTTR

International Nuclear Information System (INIS)

Takase, Kazuyuki

1988-03-01

This study was performed in order to investigate flow-induced vibration characteristics of a fuel rod in HTTR (High Temperature engineering Test Reactor) from both an experiment and a numerical simulation. Two kinds of fuel rods were used in this experiment: one was a graphite rod which simulated a specification of the HTTR's fuel rod and the other was an aluminum rod whose weight was a half of the graphite one. The experiment was carried out up to Re = 31000 using air at room temperature and pressure. Air flowed downstream in an annular passage which consisted of the fuel rod and the graphite channel. Numerical simulations by fluid and frequency equations were also carried out. Numerical and experimental results were then compared. The following conclusions were drived: (1) The fuel rod amplitudes increase with the flow rate and with a decrease of the fuel rod weight. (2) The fuel rod amplitudes are obtained by δ/De = 2.22 x 10 -10 Re 1.43 , 9000 ≤ Re ≤ 31000, where δ is a vibration amplitude, De is a hydraulic diameter and Reis Reynolds number. (3) The fuel rod frequencies shift from lower natural frequency to higher as the flow rate increases. (4) The flow-induced vibration behavior of the fuel rod can simulate well by simultaneous equations which used the turbulence model for fluid and the mass model for vibration of the fuel rod. (author)

Vibration-induced displacement using high-frequency resonators and friction layers

DEFF Research Database (Denmark)

Thomsen, Jon Juel

1998-01-01

A mathematical model is set up to quantify vibration-induced motions of a slider with an imbedded resonator. A simple approximate expression is presented for predicting average velocities of the slider, agreeing fairly well with numerical integration of the full equations of motion. The simple ex...

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

Science.gov (United States)

Delor, Milan; Archer, Stuart A.; Keane, Theo; Meijer, Anthony J. H. M.; Sazanovich, Igor V.; Greetham, Gregory M.; Towrie, Michael; Weinstein, Julia A.

2017-11-01

Ultrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer donor-bridge-acceptor-bridge-donor 'fork' system: asymmetric 13C isotopic labelling of one of the two -C≡C- bridges makes the two parallel and otherwise identical donor→acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UVpump(excitation)-IRpump(perturbation)-IRprobe(monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices.

Scale-model characterization of flow-induced vibrational response of FFTF reactor internals

International Nuclear Information System (INIS)

Ryan, J.A.; Mahoney, J.J.

1980-10-01

Fast Test Reactor core internal and peripheral components were assessed for flow-induced vibrational characteristics under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup as an integral part of the Fast Test Reactor Vibration Program. The Hydraulic Core Mockup was an 0.285 geometric scale model of the Fast Test Reactor internals designed to simulate prototype vibrational and hydraulic characteristics. Using water to simulate sodium coolant, vibrational characteristics were measured and determined for selected model components over the scaled flow range of 36 to 110%. Additionally, in-situ shaker tests were conducted on selected Hydraulic Core Mockup outlet plenum components to establish modal characteristics. Most components exhibited resonant response at all test flow rates; however, the measured dynamic response was neither abnormal nor anomalously flow-rate dependent, and the predicted prototype components' response were deemed acceptable

Controlling flow-induced vibrations of flood barrier gates with data-driven and finite-element modelling

NARCIS (Netherlands)

Erdbrink, C.D.; Krzhizhanovskaya, V.V.; Sloot, P.M.A.; Klijn, F.; Schweckendiek, T.

2012-01-01

Operation of flood barrier gates is sometimes hampered by flow-induced vibrations. Although the physics is understood for specific gate types, it remains challenging to judge dynamic gate behaviour for unanticipated conditions. This paper presents a hybrid modelling system for predicting vibrations

Vibration analysis and vibration damage assessment in nuclear and process equipment

International Nuclear Information System (INIS)

Pettigrew, M.J.; Taylor, C.E.; Fisher, N.J.; Yetisir, M.; Smith, B.A.W.

1997-01-01

Component failures due to excessive flow-induced vibration are still affecting the performance and reliability of process and nuclear components. The purpose of this paper is to discuss flow-induced vibration analysis and vibration damage prediction. Vibration excitation mechanisms are described with particular emphasis on fluid elastic instability. The dynamic characteristics of process and power equipment are explained. The statistical nature of some parameters, in particular support conditions, is discussed. The prediction of fretting-wear damage is approached from several points-of-view. An energy approach to formulate fretting-wear damage is proposed. (author)

Raynaud′s phenomenon among men and women with noise-induced hearing loss in relation to vibration exposure

Directory of Open Access Journals (Sweden)

Hans Pettersson

2014-01-01

Full Text Available Raynaud′s phenomenon is characterized by constriction in blood supply to the fingers causing finger blanching, of white fingers (WF and is triggered by cold. Earlier studies found that workers using vibrating hand-held tools and who had vibration-induced white fingers (VWF had an increased risk for hearing loss compared with workers without VWF. This study examined the occurrence of Raynaud′s phenomenon among men and women with noise-induced hearing loss in relation to vibration exposure. All 342 participants had a confirmed noise-induced hearing loss medico legally accepted as work-related by AFA Insurance. Each subject answered a questionnaire concerning their health status and the kinds of exposures they had at the time when their hearing loss was first discovered. The questionnaire covered types of exposures, discomforts in the hands or fingers, diseases and medications affecting the blood circulation, the use of alcohol and tobacco and for women, the use of hormones and whether they had been pregnant. The participation rate was 41% (n = 133 with 38% (n = 94 for men and 50% (n = 39 for women. 84 men and 36 women specified if they had Raynaud′s phenomenon and also if they had used hand-held vibrating machines. Nearly 41% of them had used hand-held vibrating machines and 18% had used vibrating machines at least 2 h each workday. There were 23 men/6 women with Raynaud′s phenomenon. 37% reported WF among those participants who were exposed to hand-arm vibration (HAV and 15% among those not exposed to HAV. Among the participants with hearing loss with daily use of vibrating hand-held tools more than twice as many reports WF compared with participants that did not use vibrating hand-held tools. This could be interpreted as Raynaud′s phenomenon could be associated with an increased risk for noise-induced hearing loss. However, the low participation rate limits the generalization of the results from this study.

Numerical simulation of flow-induced vibrations in tube bundles

International Nuclear Information System (INIS)

Elisabeth Longatte; Zaky Bendjeddou; Mhamed Souli

2005-01-01

Full text of publication follows: In many industrial components mechanical structures like rod cluster control assembly, fuel assembly and heat exchanger tube bundles are submitted to complex flows causing possible vibrations and damage. Fluid forces are usually split into two parts: structure motion independent forces and fluid-elastic forces coupled with tube motion and responsible for possible dynamic instability development leading to possible short term failures through high amplitude vibrations. Most classical fluid force identification methods rely on structure response experimental measurements associated with convenient data processes. Owing to recent improvements in Computational Fluid Dynamics (C.F.D.), numerical fluid force identification is now practicable in the presence of industrial configurations. The present paper is devoted to numerical simulation of flow-induced vibrations of tube bundles submitted to single-phase cross flows by using C.F.D. codes. Direct Numerical Simulation (D.N.S.), Arbitrary Lagrange Euler formulation (A.L.E.) and code coupling process are involved to predict fluid forces responsible for tube bundle vibrations in the presence of fluid structure and fluid-elastic coupling effects. In the presence of strong multi-physics coupling, simulation of flow-induced vibrations requires a fluid structure code coupling process. The methodology consists in solving in the same time thermohydraulics and mechanics problems by using an A.L.E. formulation for the fluid computation. The purpose is to take into account coupling between flow and structure motions in order to be able to capture coupling effects. From a numerical point of view, there are three steps in the computation: the fluid problem is solved on the computational domain; fluid forces acting on the moving tube are estimated; finally they are introduced in the structure solver providing the tube displacement that is used to actualize the fluid computational domain. Specific

Two improvements on numerical simulation of 2-DOF vortex-induced vibration with low mass ratio

Science.gov (United States)

Kang, Zhuang; Ni, Wen-chi; Zhang, Xu; Sun, Li-ping

2017-12-01

Till now, there have been lots of researches on numerical simulation of vortex-induced vibration. Acceptable results have been obtained for fixed cylinders with low Reynolds number. However, for responses of 2-DOF vortex-induced vibration with low mass ratio, the accuracy is not satisfactory, especially for the maximum amplitudes. In Jauvtis and Williamson's work, the maximum amplitude of the cylinder with low mass ratio m*=2.6 can reach as large as 1.5 D to be called as the "super-upper branch", but from current literatures, few simulation results can achieve such value, even fail to capture the upper branch. Besides, it is found that the amplitude decays too fast in the lower branch with the RANS-based turbulence model. The reason is likely to be the defects of the turbulence model itself in the prediction of unsteady separated flows as well as the unreasonable setting of the numerical simulation parameters. Aiming at above issues, a modified turbulence model is proposed in this paper, and the effect of the acceleration of flow field on the response of vortex-induced vibration is studied based on OpenFOAM. By analyzing the responses of amplitude, phase and trajectory, frequency and vortex mode, it is proved that the vortex-induced vibration can be predicted accurately with the modified turbulence model under appropriate flow field acceleration.

The vibration measurements at the photon factory storage ring building

International Nuclear Information System (INIS)

Haga, K.; Nakayama, M.; Masuda, K.; Ishizaki, H.; Kura, M.; Meng, L.; Oku, Y.

1999-01-01

The Photon Factory is a 2.5 GeV electron storage ring and has been operating since 1982 as a dedicated SR source. At the Photon Factory, we have been pursuing the various sources of the beam instabilities which deteriorated the SR beam quality in the wide frequency range. Some of the sources were the vibrations of magnets and floor of the ring tunnel, temperature change of the cooling water and the elongation of the storage ring building roof due to sunshine that induced the diurnal motion of the SR beam axis. This article presents the results of the vibration measurements that have been performed at the Photon Factory storage ring building. (1) The vibrations of the ring tunnel floor and the experimental hall floor, comparing with the vibration of the ground surrounding the storage ring building, are same order in the 1 ∼ 5 Hz range, and 1/3 ∼ 1/5 in the 5 ∼ 100 Hz range, in the vertical and the horizontal direction. (2) The effects of the vibration arising from the operating eight air-conditioners can be seen in the Fourier spectrum of the vibration of the ring tunnel floor, experimental floor, Q-magnets and BPM vacuum duct. (3) The vibrations of the Q-magnet and girder at frequencies near their fundamental resonant frequencies have been amplified 100 limes in the lateral direction comparing to the floor vibration. (4) Correlation between the vibration of the BPM vacuum duct and the vibration of the electron beam motion is unknown for the lack of the precise data. (authors)

Characterizing human activity induced impulse and slip-pulse excitations through structural vibration

Science.gov (United States)

Pan, Shijia; Mirshekari, Mostafa; Fagert, Jonathon; Ramirez, Ceferino Gabriel; Chung, Albert Jin; Hu, Chih Chi; Shen, John Paul; Zhang, Pei; Noh, Hae Young

2018-02-01

Many human activities induce excitations on ambient structures with various objects, causing the structures to vibrate. Accurate vibration excitation source detection and characterization enable human activity information inference, hence allowing human activity monitoring for various smart building applications. By utilizing structural vibrations, we can achieve sparse and non-intrusive sensing, unlike pressure- and vision-based methods. Many approaches have been presented on vibration-based source characterization, and they often either focus on one excitation type or have limited performance due to the dispersion and attenuation effects of the structures. In this paper, we present our method to characterize two main types of excitations induced by human activities (impulse and slip-pulse) on multiple structures. By understanding the physical properties of waves and their propagation, the system can achieve accurate excitation tracking on different structures without large-scale labeled training data. Specifically, our algorithm takes properties of surface waves generated by impulse and of body waves generated by slip-pulse into account to handle the dispersion and attenuation effects when different types of excitations happen on various structures. We then evaluate the algorithm through multiple scenarios. Our method achieves up to a six times improvement in impulse localization accuracy and a three times improvement in slip-pulse trajectory length estimation compared to existing methods that do not take wave properties into account.

Numerical research of a super-large cooling tower subjected to accidental loads

Energy Technology Data Exchange (ETDEWEB)

Li, Yi; Lin, Feng [Department of Building Engineering, Tongji University, Shanghai 200092 (China); Gu, Xianglin, E-mail: gxl@tongji.edu.cn [Department of Building Engineering, Tongji University, Shanghai 200092 (China); Lu, Xiaoqin [Guangdong Electric Power Design Institute, Guangzhou 510660 (China)

2014-04-01

With the continued development of nuclear power plants, more and more super-large cooling towers are to be built in China and around the world. For the safe operation of nuclear power plants, research work has been done on the causes of collapse of cooling towers, collapse modes and the secondary disasters caused by the collapse of cooling towers. However, the collapse modes and the ground vibration induced by the collapse of cooling towers subjected to the accidental loads have not been fully understood. This paper has been focused on the modes and mechanisms behavior of the collapse of cooling towers subjected to accidental loads. Meanwhile, prediction of the ground vibration due to the collapse of the cooling towers has also been completed in a parallel project. Using dynamic finite element program LS-DYNA, a 3D finite element model for a super-large cooling tower was developed and the nonlinear material models were incorporated. In this paper, four types of accidental loads were considered to trigger the collapse or local failure of the tower, including vehicle collision, airplane impact, local explosion and missile attack. It was found that vehicle collision, missile attack and small TNT equivalent explosives (2 kg, 20 kg, 200 kg) might result in local failure of the cooling tower, however, the tower can still keep stable. On the other hand, large TNT equivalent explosives (2000 kg, 4500 kg) could cause severe damages in the inclined columns of the cooling tower, and lead to progressive collapse of the entire cooling tower. The two kinds of TNT equivalent explosives caused the same collapse mode while the collapsing duration was different. The airplane impacted at the throat of the cooling tower caused the local failure of shell structure of the tower, and then the progressive collapse of the cooling tower happened due to the gravitational action. The resulting collapse mode was different from that triggered by the local explosion.

Numerical research of a super-large cooling tower subjected to accidental loads

International Nuclear Information System (INIS)

Li, Yi; Lin, Feng; Gu, Xianglin; Lu, Xiaoqin

2014-01-01

With the continued development of nuclear power plants, more and more super-large cooling towers are to be built in China and around the world. For the safe operation of nuclear power plants, research work has been done on the causes of collapse of cooling towers, collapse modes and the secondary disasters caused by the collapse of cooling towers. However, the collapse modes and the ground vibration induced by the collapse of cooling towers subjected to the accidental loads have not been fully understood. This paper has been focused on the modes and mechanisms behavior of the collapse of cooling towers subjected to accidental loads. Meanwhile, prediction of the ground vibration due to the collapse of the cooling towers has also been completed in a parallel project. Using dynamic finite element program LS-DYNA, a 3D finite element model for a super-large cooling tower was developed and the nonlinear material models were incorporated. In this paper, four types of accidental loads were considered to trigger the collapse or local failure of the tower, including vehicle collision, airplane impact, local explosion and missile attack. It was found that vehicle collision, missile attack and small TNT equivalent explosives (2 kg, 20 kg, 200 kg) might result in local failure of the cooling tower, however, the tower can still keep stable. On the other hand, large TNT equivalent explosives (2000 kg, 4500 kg) could cause severe damages in the inclined columns of the cooling tower, and lead to progressive collapse of the entire cooling tower. The two kinds of TNT equivalent explosives caused the same collapse mode while the collapsing duration was different. The airplane impacted at the throat of the cooling tower caused the local failure of shell structure of the tower, and then the progressive collapse of the cooling tower happened due to the gravitational action. The resulting collapse mode was different from that triggered by the local explosion

First international symposium on Flow Induced Noise and Vibration Issues and Aspects

CERN Document Server

Rosa, Sergio; Franco, Francesco; Guyader, Jean-Louis; Hambric, Stephen; Flinovia - Flow Induced Noise and Vibration Issues and Aspects

2015-01-01

Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field. It describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation;
for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays;
for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements;
for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses. This book p...

Soft Computing Approach to Evaluate and Predict Blast-Induced Ground Vibration

Science.gov (United States)

Khandelwal, Manoj

2010-05-01

Drilling and blasting is still one of the major economical operations to excavate a rock mass. The consumption of explosive has been increased many folds in recent years. These explosives are mainly used for the exploitation of minerals in mining industry or the removal of undesirable rockmass for community development. The amount of chemical energy converted into mechanical energy to fragment and displace the rockmass is minimal. Only 20 to 30% of this explosive energy is utilized for the actual fragmentation and displacement of rockmass and rest of the energy is wasted in undesirable ill effects, like, ground vibration, air over pressure, fly rock, back break, noise, etc. Ground vibration induced due to blasting is very crucial and critical as compared to other ill effects due to involvement of public residing in the close vicinity of mining sites, regulating and ground vibration standards setting agencies together with mine owners and environmentalists and ecologists. Also, with the emphasis shifting towards eco-friendly, sustainable and geo-environmental activities, the field of ground vibration have now become an important and imperative parameter for safe and smooth running of any mining and civil project. The ground vibration is a wave motion, spreading outward from the blast like ripples spreading outwards due to impact of a stone dropped into a pond of water. As the vibration passes through the surface structures, it induces vibrations in those structures also. Sometimes, due to high ground vibration level, dwellings may get damaged and there is always confrontation between mine management and the people residing in the surroundings of the mine area. There is number of vibration predictors available suggested by different researchers. All the predictors estimate the PPV based on mainly two parameters (maximum charge used per delay and distance between blast face to monitoring point). However, few predictors considered attenuation/damping factor too. For

Risk of hearing loss among workers with vibration-induced white fingers.

Science.gov (United States)

Pettersson, Hans; Burström, Lage; Hagberg, Mats; Lundström, Ronnie; Nilsson, Tohr

2014-12-01

We examined the risk of hearing loss for workers who use hand-held vibrating tools with vibration-induced white fingers (VWF) compared to workers without VWF. Data on 184 participants from a 21-year cohort were gathered with questionnaires and measurements. The effects on hearing status of VWF, hand-arm vibration exposure, smoking habits, age and two-way interactions of these independent variables were examined with binary logistic regression. Analyses were made for the right hand and ear as well as for the hand with VWF and the ear with worse categorized hearing status. Workers with VWF in their right hand had an increased risk of hearing loss (odds ratio 2.2-2.3) in the right ear. Workers with VWF in any hand did not have any increased risk of hearing loss in the ear with worse hearing status. This study supports the hypothesis that VWF increases the risk of hearing loss among workers who use hand-held vibrating tools in a noisy environment. © 2014 Wiley Periodicals, Inc.

Evaluation of human-induced vibration of continuous footbridges

OpenAIRE

El-Robaa Ahmed; Gaawan Sameh; Malek Charles

2015-01-01

With the development of construction materials and the introduction of high strength steel and concrete, the human-induced vibration became a dominant criterion for the design of pedestrian bridges. Currently, longer spans and lightweight bridges have been comprised in most of design trends. This leads to lower the natural frequencies of the system which have a great effect on the dynamic performance of bridges subjected to human activities. Although the design of steel footbridges could reac...

Picosecond dynamics of the glutamate receptor in response to agonist-induced vibrational excitation.

Science.gov (United States)

Kubo, Minoru; Shiomitsu, Eiji; Odai, Kei; Sugimoto, Tohru; Suzuki, Hideo; Ito, Etsuro

2004-02-01

Conformational changes of proteins are dominated by the excitation and relaxation processes of their vibrational states. To elucidate the mechanism of receptor activation, the conformation dynamics of receptors must be analyzed in response to agonist-induced vibrational excitation. In this study, we chose the bending vibrational mode of the guanidinium group of Arg485 of the glutamate receptor subunit GluR2 based on our previous studies, and we investigated picosecond dynamics of the glutamate receptor caused by the vibrational excitation of Arg485 via molecular dynamics simulations. The vibrational excitation energy in Arg485 in the ligand-binding site initially flowed into Lys730, and then into the J-helix at the subunit interface of the ligand-binding domain. Consequently, the atomic displacement in the subunit interface around an intersubunit hydrogen bond was evoked in about 3 ps. This atomic displacement may perturb the subunit packing of the receptor, triggering receptor activation. Copyright 2003 Wiley-Liss, Inc.

Computer modeling of flow induced in-reactor vibrations

International Nuclear Information System (INIS)

Turula, P.; Mulcahy, T.M.

1977-01-01

An assessment of the reliability of finite element method computer models, as applied to the computation of flow induced vibration response of components used in nuclear reactors, is presented. The prototype under consideration was the Fast Flux Test Facility reactor being constructed for US-ERDA. Data were available from an extensive test program which used a scale model simulating the hydraulic and structural characteristics of the prototype components, subjected to scaled prototypic flow conditions as well as to laboratory shaker excitations. Corresponding analytical solutions of the component vibration problems were obtained using the NASTRAN computer code. Modal analyses and response analyses were performed. The effect of the surrounding fluid was accounted for. Several possible forcing function definitions were considered. Results indicate that modal computations agree well with experimental data. Response amplitude comparisons are good only under conditions favorable to a clear definition of the structural and hydraulic properties affecting the component motion. 20 refs

Noise-induced hearing loss and combined noise and vibration exposure.

Science.gov (United States)

Turcot, A; Girard, S A; Courteau, M; Baril, J; Larocque, R

2015-04-01

While there is a wide body of literature addressing noise-induced hearing loss (NIHL) and hand-arm vibration syndrome (HAVS) independently, relatively few studies have considered the combined effects of noise and vibration. These studies have suggested an increased risk of NIHL in workers with vibration white finger (VWF), though the relationship remains poorly understood. To determine whether hearing impairment is worse in noise-exposed workers with VWF than in workers with similar noise exposures but without VWF. The Quebec National Institute of Public Health audiometric database was used in conjunction with work-related accident and occupational diseases data from the Quebec workers' compensation board to analyse differences in audiometry results between vibration-exposed workers in the mining and forestry industries and the overall source population, and between mining and forestry workers with documented VWF and those without VWF. The International Organization for Standardization (ISO) 7029 standards were used to calculate hearing loss not attributable to age. 15751 vibration-exposed workers were identified in an overall source population of 59339. Workers with VWF (n = 96) had significantly worse hearing at every frequency studied (500, 1000, 2000 4000 Hz) compared with other mining and forestry workers without VWF. This study confirms previous findings of greater hearing loss at higher frequencies in workers with VWF, but also found a significant difference in hearing loss at low frequencies. It therefore supports the association between combined noise and hand-arm vibration (HAV) exposure and NIHL. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Harbor seal vibrissa morphology suppresses vortex-induced vibrations.

Science.gov (United States)

Hanke, Wolf; Witte, Matthias; Miersch, Lars; Brede, Martin; Oeffner, Johannes; Michael, Mark; Hanke, Frederike; Leder, Alfred; Dehnhardt, Guido

2010-08-01

Harbor seals (Phoca vitulina) often live in dark and turbid waters, where their mystacial vibrissae, or whiskers, play an important role in orientation. Besides detecting and discriminating objects by direct touch, harbor seals use their whiskers to analyze water movements, for example those generated by prey fish or by conspecifics. Even the weak water movements left behind by objects that have passed by earlier can be sensed and followed accurately (hydrodynamic trail following). While scanning the water for these hydrodynamic signals at a swimming speed in the order of meters per second, the seal keeps its long and flexible whiskers in an abducted position, largely perpendicular to the swimming direction. Remarkably, the whiskers of harbor seals possess a specialized undulated surface structure, the function of which was, up to now, unknown. Here, we show that this structure effectively changes the vortex street behind the whiskers and reduces the vibrations that would otherwise be induced by the shedding of vortices from the whiskers (vortex-induced vibrations). Using force measurements, flow measurements and numerical simulations, we find that the dynamic forces on harbor seal whiskers are, by at least an order of magnitude, lower than those on sea lion (Zalophus californianus) whiskers, which do not share the undulated structure. The results are discussed in the light of pinniped sensory biology and potential biomimetic applications.

Vibrations measurement in fast and PWR reactor study

International Nuclear Information System (INIS)

Tigeot, Y.; Epstein, A.; Hareux, F.

1975-01-01

In the past severe damages have occured in several nuclear reactors, by structural vibrations induced by the primary cooling flow. To avoid this kind of troubles, the SEMT makes studies for two different types of reactors. For the light pressurized water reactors, some tests have been made on the SAFRAN test loop which is a three loop 1/8 scale internal model of a 900 MWe reactor. This study is actually undertaken jointly with Framatome. Elsewhere, measurements have been made on the Phenix fast breeder sodium reactor, and studies are planned for the Super Phenix reactor [fr

Sympathetic cooling of a membrane oscillator in a hybrid mechanical-atomic system

Science.gov (United States)

Jöckel, Andreas; Faber, Aline; Kampschulte, Tobias; Korppi, Maria; Rakher, Matthew T.; Treutlein, Philipp

2015-01-01

Sympathetic cooling with ultracold atoms and atomic ions enables ultralow temperatures in systems where direct laser or evaporative cooling is not possible. It has so far been limited to the cooling of other microscopic particles, with masses up to 90 times larger than that of the coolant atom. Here, we use ultracold atoms to sympathetically cool the vibrations of a Si3N4 nanomembrane, the mass of which exceeds that of the atomic ensemble by a factor of 1010. The coupling of atomic and membrane vibrations is mediated by laser light over a macroscopic distance and is enhanced by placing the membrane in an optical cavity. We observe cooling of the membrane vibrations from room temperature to 650 ± 230 mK, exploiting the large atom-membrane cooperativity of our hybrid optomechanical system. With technical improvements, our scheme could provide ground-state cooling and quantum control of low-frequency oscillators such as nanomembranes or levitated nanoparticles, in a regime where purely optomechanical techniques cannot reach the ground state.

Inspection of arterial-induced skin vibration by Moire fringe with two-dimensional continuous wavelet transform

Science.gov (United States)

Wang, Chun-Hsiung; Chiu, Shih-Yung; Hsu, Yu-Hsiang; Lee, Shu-Sheng; Lee, Chih-Kung

2017-06-01

A non-contact arterial-induced skin vibration inspection system is implemented. This optical metrology system is constructed with shadow Moiré configuration and the fringe analysis algorithm. Developed with the Region of Interested (ROI) capturing technique and the Two-dimensional Wavelet Transform (2D-CWT) method, this algorithm is able to retrieve the height-correlated phase information from the shadow Moiré fringe patterns. Using a commercial video camera or a CMOS image sensor, this system could monitor the skin-vibration induced by the cyclic deformation of inner layered artery. The cross-sectional variation and the rhythm of heart cycle could be continuously measured for health monitoring purposes. The average vibration amplitude of the artery at the wrist ranges between 20 μm and 50 μm, which is quite subtle comparing with the skin surface structure. Having the non-stationary motion of human body, the traditional phase shifting (PS) technique can be very unstable due to the requirement of several frames of images, especially for case that artery is continuously pumping. To bypass this fundamental issue, the shadow Moiré technique is introduced to enhance the surface deformation characteristic. And the phase information is retrieved by the means of spectrum filtering instead of PS technique, which the phase is calculated from intensity maps of multiple images. The instantaneous surface can therefore be reconstructed individually from each frame, enabling the subtle arterial-induced skin vibration measurement. The comparative results of phase reconstruction between different fringe analysis algorithms will be demonstrated numerically and experimentally. And the electrocardiography (ECG) results will used as the reference for the validity of health monitoring potential of the non-contact arterial-induced skin vibration inspection system.

Health Assessment of Cooling Fan Bearings Using Wavelet-Based Filtering

Directory of Open Access Journals (Sweden)

Qiang Miao

2012-12-01

Full Text Available As commonly used forced convection air cooling devices in electronics, cooling fans are crucial for guaranteeing the reliability of electronic systems. In a cooling fan assembly, fan bearing failure is a major failure mode that causes excessive vibration, noise, reduction in rotation speed, locked rotor, failure to start, and other problems; therefore, it is necessary to conduct research on the health assessment of cooling fan bearings. This paper presents a vibration-based fan bearing health evaluation method using comblet filtering and exponentially weighted moving average. A new health condition indicator (HCI for fan bearing degradation assessment is proposed. In order to collect the vibration data for validation of the proposed method, a cooling fan accelerated life test was conducted to simulate the lubricant starvation of fan bearings. A comparison between the proposed method and methods in previous studies (i.e., root mean square, kurtosis, and fault growth parameter was carried out to assess the performance of the HCI. The analysis results suggest that the HCI can identify incipient fan bearing failures and describe the bearing degradation process. Overall, the work presented in this paper provides a promising method for fan bearing health evaluation and prognosis.

Planar measurements of spray-induced wall cooling using phosphor thermometry

Science.gov (United States)

Dragomirov, Plamen; Mendieta, Aldo; Abram, Christopher; Fond, Benoît; Beyrau, Frank

2018-03-01

The wall cooling induced by spray impingement is investigated using phosphor thermometry. Thin coatings of zinc oxide (ZnO) phosphor were applied with a transparent chemical binder onto a steel surface. Instantaneous spatially resolved temperatures were determined using the spectral intensity ratio method directly after the injection of UV-grade hexane onto the surface using a commercial gasoline injector. The investigations showed that 2D temperature measurements with high spatial and shot-to-shot precision of, respectively, 0.5 and 0.6 K can be achieved, allowing the accurate resolution of the cooling induced by the spray. The presence of a liquid film over the phosphor coating during measurements showed no noticeable influence on the measured temperatures. However, in some cases a change in the intensity ratio at the spray impingement area, in the form of a permanent "stain", could be observed after multiple injections. The formation of this stain was less likely with increasing annealing time of the coating as well as lower plate operating temperatures during the injection experiments. Finally, the experimental results indicate a noticeable influence of the thickness of the phosphor coating on the measured spray-induced wall cooling history. Hence, for quantitative analysis, a compromise between coating thickness and measurement accuracy needs to be considered for similar applications where the heat transfer rates are very high.

Methodology to monitor and diagnostic vibrations of the motor-pumps used in the primary cooling system of IEAR-1 nuclear research reactor

International Nuclear Information System (INIS)

Benevenuti, Erion de Lima

2004-01-01

The objectives of this study are to establish a strategy to monitor and diagnose vibrations of the motor pumps used in the primary reactor cooling system of the IEA-R1 nuclear research reactor, to verify the possibility of using the existing installed monitoring vibration system and to implement such strategy in a continuous way. Four types of mechanical problems were considered: unbalancing, misalignment, gaps and faults in bearings. An adequate set of analysis tools, well established by the industry, was selected. These are: global measurements of vibration, velocity spectrum and acceleration envelope spectrum. Three sources of data and information were used; the data measured from the primary pumps, experimental results obtained with a Spectra Quest machine used to simulate mechanical defects and data from the literature. The results show that, for the specific case of the motor-pumps of IEA-R1 nuclear research reactor, although the technique using the envelope of acceleration, which is not available in the current system used to monitor the vibration of the motor pumps, is the one with best performance, the other techniques available in the system are sufficient to monitor the four types of mechanical problems mentioned. The proposed strategy is shown and detailed in this work. (author)

A Numerical Study on the Screening of Blast-Induced Waves for Reducing Ground Vibration

Science.gov (United States)

Park, Dohyun; Jeon, Byungkyu; Jeon, Seokwon

2009-06-01

Blasting is often a necessary part of mining and construction operations, and is the most cost-effective way to break rock, but blasting generates both noise and ground vibration. In urban areas, noise and vibration have an environmental impact, and cause structural damage to nearby structures. Various wave-screening methods have been used for many years to reduce blast-induced ground vibration. However, these methods have not been quantitatively studied for their reduction effect of ground vibration. The present study focused on the quantitative assessment of the effectiveness in vibration reduction of line-drilling as a screening method using a numerical method. Two numerical methods were used to analyze the reduction effect toward ground vibration, namely, the “distinct element method” and the “non-linear hydrocode.” The distinct element method, by particle flow code in two dimensions (PFC 2D), was used for two-dimensional parametric analyses, and some cases of two-dimensional analyses were analyzed three-dimensionally using AUTODYN 3D, the program of the non-linear hydrocode. To analyze the screening effectiveness of line-drilling, parametric analyses were carried out under various conditions, with the spacing, diameter of drill holes, distance between the blasthole and line-drilling, and the number of rows of drill holes, including their arrangement, used as parameters. The screening effectiveness was assessed via a comparison of the vibration amplitude between cases both with and without screening. Also, the frequency distribution of ground motion of the two cases was investigated through fast Fourier transform (FFT), with the differences also examined. From our study, it was concluded that line-drilling as a screening method of blast-induced waves was considerably effective under certain design conditions. The design details for field application have also been proposed.

Physical and numerical investigation of the flow induced vibration of the hydrofoil

Science.gov (United States)

Wu, Q.; Wang, G. Y.; Huang, B.

2016-11-01

The objective of this paper is to investigate the flow induced vibration of a flexible hydrofoil in cavitating flows via combined experimental and numerical studies. The experiments are presented for the modified NACA66 hydrofoil made of POM Polyacetate in the closed-loop cavitation tunnel at Beijing Institute of Technology. The high-speed camera and the single point Laser Doppler Vibrometer are applied to analyze the transient flow structures and the corresponding structural vibration characteristics. The hybrid coupled fluid structure interaction model is conducted to couple the incompressible and unsteady Reynolds Averaged Navier-Stokes solver with a simplified two-degree-of-freedom structural model. The k-ω SST turbulence model with the turbulence viscosity correction and the Zwart cavitation model are introduced to the present simulations. The results showed that with the decreasing of the cavitation number, the cavitating flows display incipient cavitation, sheet cavitation, cloud cavitation and supercavitation. The vibration magnitude increases dramatically for the cloud cavitation and decline for the supercavitation. The cloud cavitation development strongly affects the vibration response, which is corresponding to the periodically developing and shedding of the large-scale cloud cavity. The main frequency of the vibration amplitude is accordance with the cavity shedding frequency and other two frequencies of the vibration amplitude are corresponding to the natural frequencies of the bending and twisting modes.

Study of the levels of serum cortisol and gastrin in dogs with vibration-induced injury

International Nuclear Information System (INIS)

Wei Zikun

2005-01-01

Objective: To study the changes of levels of serum cortisol and gastrin in dogs with vibration-induced injury for providing better treatment regimen. Methods: In this experiment, 8 or 10 domestic dogs were placed on each of four sites away from explosion center about 0, 100, 200, 300 meters respectively. The dogs were standing uncontrolled or lying right side down under anesthesia. Serum cortisol and gastrin levels were detected with RIA both before and after explosion. Results: The levels of serum cortisol and gastrin began to fall about 24 hours after explosion. The serum levels of cortisol were still decreased significantly after 9 days and 17 days. Conclusion: The levels of the serum cortisol declined when the animals were injured by vibration. Detection of serum cortisol levels might lead to definitive diagnosis and supplemental treatment with cortical hormones for vibration-induced injury. (authors)

Active control of annular flow-induced vibration of axisymmetric elastic beam by the local gap width control

International Nuclear Information System (INIS)

Takada, Shoji; Shintani, Atsuhiko; Ito, Tomohiro; Fujita, Katsuhisa

2011-01-01

Flow-induced vibration may occur in the structures such as elastic beams subjected to annular flow in the narrow passage. Once the flow-induced vibration occurs, vibration amplitude becomes larger, consequently it causes a lot of troubles such as fatigue or failure in mechanical structures. In this paper, for the purpose to avoid these troubles, the active control of vibration of an axisymmetric elastic beam subjected to annular flow is investigated. An air-pressured actuator is attached on the surface of the circular cylinder for the vibrational control. As the shape of the actuator changes by control, the gap width in narrow passage changes, which causes the change of the fluid pressure. Therefore, the vibration of the fluid-structure coupled system can be suppressed. The fluid-structure coupled equation based on the Euler-Bernoulli type of partial differential equation and the Navier-Stokes equations is analytically derived including control terms. By applying the optimal control law to the coupled system, the unstable behavior is stabilized. The stability of the coupled system is investigated by eigenvalue analyses of controlled coupled equations. Numerical simulations are performed to investigate the efficiency of the proposed control method. (author)

Numerical method to calculate flow-induced vibration in turbulent flow. 3rd Report. Analysis of vortex-induced vibration in an array of elastically supported tubes; Ranryuba ni okeru ryutai kozotai rensei shindo kaiseki shuho no kaihatsu. 3. Kangun ni okeru uzu reiki shindo kaiseki

Energy Technology Data Exchange (ETDEWEB)

Sadaoka, N.; Umegaki, K. [Hitachi, Ltd., Tokyo (Japan)

1996-01-25

A vortex-induced vibration of an array of elastically supported tubes is simulated in two-dimension by using a flow-induced vibration analysis program, which was developed in order to evaluate flow-induced vibration in various components such as heat exchangers. From a comparison of calculated results and experimental data, the following points are observed. (1) For the calculated results in a 5 {times} 5 square array, the flow pattern surrounding the first-row tubes is markedly different from that observed in the second-row or third-row tubes. This flow pattern is the same as that obtained from the experiment. (2) All tubes begin to oscillate due to unsteady fluid force and the oscillating mode is different for each row of tubes. These oscillation patterns show the same tendency in the experiments and it is concluded that the developed method can simulate vortex-induced vibration in an array of elastically supported tubes. 19 refs., 10 figs., 1 tab.

Calculation of the ex-core neutron noise induced by fuel vibrations in PWRs

International Nuclear Information System (INIS)

Tran Hoai Nam; Cao Van Chung; Hoang Thanh Phi Hung; Hoang Van Khanh

2015-01-01

Calculation of the neutron noise induced by fuel assembly vibrations in two pressurized water reactor (PWR) cores has been performed to investigate the effect of cycle burnup on the properties of the ex-core detector noise. Pendular vibrations of individual fuel assemblies were assumed to occur at different locations in the core. The auto power spectra density (APSD) of the ex-core detector noise was evaluated with the assumption of stochastic vibrations along a random two-dimensional trajectory. The results show that no general monotonic variation of APSD was found. The increase of APSD occurs predominantly for peripheral assemblies. Assuming simultaneous vibrations of a number of fuel assemblies uniformly distributed over the core with the more realistic perturbation model, the effect of the peripheral assemblies will dominate and the increase of the amplitude of the ex-core neutron noise with burnup can be confirmed. (author)

Factors Influencing the Effectiveness of Scalp Cooling in the Prevention of Chemotherapy-Induced Alopecia

OpenAIRE

Komen, Manon M.C.; Smorenburg, Carolien H.; van den Hurk, Corina J.G.; Nortier, Johan W.R.

2013-01-01

The success of scalp cooling in preventing or reducing chemotherapy-induced alopecia (CIA) is highly variable. In a review of the literature, this study found that the factors influencing the effectiveness of scalp cooling to prevent CIA in patients with cancer include chemotherapy type and dose, as well as the degree and duration of cooling.

Axial-flow-induced vibration for a rod supported by translational springs at both ends

International Nuclear Information System (INIS)

Kang, H.S.; Song, K.N.; Kim, H.K.; Yoon, K.H.

2003-01-01

An axial-flow-induced vibration model was proposed for a rod supported by two translational springs at both ends in order to evaluate the sensitivity to spring stiffness on the FIV for a PWR fuel rod. For developing the model, a one-mode approximation was made based on the assumption that the first mode was dominant in vibration behavior of the single span rod. The first natural frequency and mode shape functions for the flow-induced vibration, called the FIV, model were derived by using Lagrange's method. The vibration displacements were calculated by both of the spring-supported rod and the simple-supported (SS) one. As a result, the vibration displacement for the spring-supported (50 kN m -1 ) rod was 15-20% larger than that of the SS rod when the rods are in axial flow of 5-8 m s -1 velocity. The discrepancy between both displacements became much larger as flow velocity increased, and that of the rod having the short span length was larger than that of the rod having the long span length although the displacement value itself of the long span rod was larger than that of the short one. The vibration displacement for the spring-supported rod appeared to decrease with the increase of the spring constant. Since single span beam supported by the two translational springs are focused on in this paper, further study will be needed to reflect more realistic supporting conditions of the PWR fuel rod such as two springs and four dimples and cross or swirling flow caused by the mixing vane of the spacer grid

Flow and flow-induced vibration of a square array of cylinders in steady currents

Energy Technology Data Exchange (ETDEWEB)

Zhao, Ming [School of Computing, Engineering and Mathematics, University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751 (Australia); Cheng, Liang; An, Hongwei; Tong, Feifei, E-mail: m.zhao@uws.edu.au [School of Civil, Environmental and Mining Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

2015-08-15

Flow and flow-induced vibration of a square array of cylinders are investigated by two-dimensional numerical simulations. Flow past 36 cylinders in an inline arranged square array and 33 cylinders in a staggered arranged square array is firstly simulated, for Re = 100 and the spacing ratios of L/D = 1.5, 2, 3, 4, 5. Only one vortex street is observed in the wake of the cylinder array when the spacing ratio is 1.5 in the inline arrangement and 1.5 and 2 in the staggered arrangement, indicating that the critical spacing ratio for the single-vortex street mode in the staggered arrangement is higher than that in the inline arrangement. The vortex shedding from the cylinders is suppressed at L/D = 3 for both inline and staggered arrangements. Vortex shedding from each individual cylinder is observed when L/D = 4. Flow-induced vibration of 36 cylinders in an inline square arrangement is studied for a constant Reynolds number of 100, two spacing ratios of 2 and 5, a constant mass ratio of 2.5 and a wide range of reduced velocities. It is found that for a spacing ratio of 2, the vibration of the cylinders in the four downstream columns does not start until the reduced velocity exceeds 4.5. The vibration of the cylinders progresses downstream with increasing reduced velocity. For a spacing ratio of 5, the vibrations of the cylinders in the most upstream column are similar to that of a single cylinder. The vibration amplitudes of the downstream cylinders peak at higher reduced velocities than that of a single cylinder. The maximum possible response amplitudes occur at the most downstream cylinders. (paper)

Vibrational Stability of NLC Linac and Final Focus Components

Energy Technology Data Exchange (ETDEWEB)

Le Pimpec, Frederic

2002-09-25

Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structure and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. Design to properly decouple the structure vibrations from the linac quadrupoles is being pursued.

Noise-Induced Hearing Loss in Relation With Vibration Disease and Exposure to Vibration Among Employees in Latvia

Directory of Open Access Journals (Sweden)

Kristina Karganova

2016-05-01

Full Text Available Occupational noise-induced hearing loss (ONIHL is a form of sensorineural hearing loss that is caused by intensive and continuous exposure to noise. It is one of the most frequently encountered occupational diseases worldwide despite numerous available control measures. ONIHL is a preventable disease, however, once the damage to the inner ear structures has occurred no medical intervention can reverse it. Aim. The purpose of this study was to describe and analyse incidence of registered cases of ONIHL in relation to vibration disease and exposure to vibration among employees in Latvia between 2005 and 2014. Materials and methods. The data used in the study were acquired from the Latvian State Register of Patients with Occupational Diseases and afterwards analyzed with applicable statistical tests using both Excel and IBM SPSS programmes to compare epidemiological parameters between ONIHL, vibration disease (VD and exposure to vibration and to identify the association between them. Results. In total data were obtained about 2302 patients with 2562 cases of occupational ear, nose and throat (ENT diseases. Out of them ONIHL was registered in 1699 cases (819 cases were ONIHL in combination with VD. Most of the employees with ONIHL and ONIHL simultaneously with VD were males aged 55-64. There was found statistically significant association between ONIHL and VD (p<0.001; Cramer’s V=0.42; OR=32.08; 95% confidence interval (95% CI 19.62–52.45. Statistically significant association was encountered between ONIHL and exposure to vibration as well (p<0.001; Cramer’s V=0.46; OR=10.97; 95% CI: 8.63–13.96. Conclusion. In total ONIHL was the most prevalent occupational ENT disease followed by chronic laryngitis, chronic pharyngitis and allergic rhinitis. Statistically significant association was found between ONIHL and VD, and ONIHL and exposure to vibration. Study revealed that hearing quality of workers employed in manufacturing; transport, storage

Concorde noise-induced building vibrations: International Airport Dulles. [studies by Langley Research Center

Science.gov (United States)

Mayes, W. H.; Scholl, H. F.; Stephens, D. G.; Holliday, B. G.; Deloach, R.; Finley, T. D.; Holmes, H. K.; Lewis, R. B.; Lynch, J. W.

1977-01-01

A series of studies were conducted to assess the noise-induced building vibrations associated with Concorde operations. The vibration levels of windows, walls, and floors were measured along with the associated noise levels of Concorde, subsonic aircraft and some nonaircraft events. Test sites included Sully Plantation which is adjacent to Dulles International Airport and three residential homes located in Montgomery County, Maryland. The measured vibration response levels due to Concorde operations were found to be: (1) higher than the levels due to other aircraft, (2) less than the levels due to certain household events which involve direct impulsive loading such as door and window closing, (3) less than criteria levels for building damage, and (4) comparable to levels which are perceptible to people.

Interface tuning of current-induced cooling in molecular circuits

Czech Academy of Sciences Publication Activity Database

Foti, Giuseppe; Vázquez, Héctor

2017-01-01

Roč. 121, č. 2 (2017), s. 1082-1088 ISSN 1932-7447 R&D Projects: GA ČR GA15-19672S Institutional support: RVO:68378271 Keywords : current-induced heating and cooling * molecular junction * Carbene Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.536, year: 2016

Experimental and analytical studies on pedestrian induced footbridge vibrations

DEFF Research Database (Denmark)

Gudmundsson, Gudmundur Valur; Ingólfsson, Einar Thór; Einarsson, Baldvin

2007-01-01

characteristics and to measure the response of the bridges to human induced excitation such as walking, running and jumping. Two of the bridges were a part of a design competition related to the realignment of an existing highway in the city centre of Reykjavik in 2005. The bridges have similar cross sections...... modes corresponding to the measured values. The models were subsequently used to calculate the predicted acceleration according to the preliminary version of the Eurocode (ENV 1992-2: Concrete bridges) using time-history analysis with a moving load as representative for a single pedestrian. The load...... models describing human-induced vibrations on structures in current literature and standards are explained, both for a single person walking or running and crowd loading. The measured vertical acceleration induced by single pedestrians was compared against the predictions and it was found that all...

Study of flow induce vibration inside 3.5 inch hard disk drives

Directory of Open Access Journals (Sweden)

Wichitpon Seepangmon

2014-06-01

Full Text Available This study focused on flow induced vibration of head stack assembly (HSA in a 3.5 inch hard disk drive with 5 disks and 10 read/write heads. We studied the effects of air flow on gimbal flex and resonance on arm. The comparison of vibrations on slider between the normal model and the experiment has been done for verifying the model. The peaks of frequency in experiment match the normal model at 1,040 1,320 and 1,400 Hz respectively. After that, the RNG K-ε turbulence model was used to determine the turbulent air flow of 7,200 rpm hard disk drive. The comparison between the normal model and the model with spoiler was investigated by using, computational fluid dynamics software (ANSYS and FLUENT. The results shown velocity magnitudes at the arm were decreased by 0.725 - 57.689 % and pressure dropped by 74.028 - 87.222 %. The velocity magnitudes at the gimbal flex were decreased by 5.522 - 14.291 % and pressure dropped by 48.440 - 82.947 %. The peak of vibrations on arm and gimbal flex was occurred at the frequency 1200 Hz. The model with spoiler could reduce vibration at arm by 2.56 - 95.601 % and reduce vibration at gimbal flex by 4.065 - 95.503 %. In the conclusion, the model with a spoiler could decrease the vibration at all surface of the arm and gimbal flex due to the velocity and pressure reduction[1][4].

Acute whole-body cooling for exercise-induced hyperthermia: a systematic review.

Science.gov (United States)

McDermott, Brendon P; Casa, Douglas J; Ganio, Matthew S; Lopez, Rebecca M; Yeargin, Susan W; Armstrong, Lawrence E; Maresh, Carl M

2009-01-01

To assess existing original research addressing the efficiency of whole-body cooling modalities in the treatment of exertional hyperthermia. During April 2007, we searched MEDLINE, EMBASE, Scopus, SportDiscus, CINAHL, and Cochrane Reviews databases as well as ProQuest for theses and dissertations to identify research studies evaluating whole-body cooling treatments without limits. Key words were cooling, cryotherapy, water immersion, cold-water immersion, ice-water immersion, icing, fanning, bath, baths, cooling modality, heat illness, heat illnesses, exertional heatstroke, exertional heat stroke, heat exhaustion, hyperthermia, hyperthermic, hyperpyrexia, exercise, exertion, running, football, military, runners, marathoner, physical activity, marathoning, soccer, and tennis. Two independent reviewers graded each study on the Physiotherapy Evidence Database (PEDro) scale. Seven of 89 research articles met all inclusion criteria and a minimum score of 4 out of 10 on the PEDro scale. After an extensive and critical review of the available research on whole-body cooling for the treatment of exertional hyperthermia, we concluded that ice-water immersion provides the most efficient cooling. Further research comparing whole-body cooling modalities is needed to identify other acceptable means. When ice-water immersion is not possible, continual dousing with water combined with fanning the patient is an alternative method until more advanced cooling means can be used. Until future investigators identify other acceptable whole-body cooling modalities for exercise-induced hyperthermia, ice-water immersion and cold-water immersion are the methods proven to have the fastest cooling rates.

Numerical investigation on flow-induced vibration of a triangular cylinder at a low Reynolds number

Energy Technology Data Exchange (ETDEWEB)

Wang, Huakun; Zhao, Dongliang; Yang, Wenyu; Yu, Guoliang, E-mail: yugl@sjtu.edu.cn [State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, People’s Republic of China (China)

2015-02-01

Flow-induced vibration (FIV) of a triangular cylinder is numerically investigated at a Reynolds number of Re = 100. The four-step fractional finite element method is employed to solve the two-dimensional (2D) incompressible Navier–Stokes equations. The cylinder is endowed with a two-degree-of-freedom motion with the reduced mass ratio of M{sub r} = 2. Three typical flow incidence angles, α = 0°, 30° and 60°, are examined to identify the effect of incidence angle on the vibration characteristics of the cylinder. For each α, computations are conducted in a wide range of reduced velocities 2 U{sub r} ≤ 18. The numerical results show that at α = 0° and 30°, the responses of the cylinder are dominated by vortex-induced vibration which resembles that of a circular cylinder. At α = 0°, the peak amplitude of transverse vibration is the smallest among the three investigated α, and most of the cylinder motions exhibit a regular figure-eight trajectory. Some single-loop trajectories are observed at α = 30°, where the vibration frequency in the in-line direction is always identical to that in the transverse direction. At α = 60°, the triangular cylinder undergoes a typical transverse galloping with large amplitude and low frequency, and the vibration trajectories appear to be regular or irregular figure-eight patterns, which are strongly affected by the reduced velocity. (paper)

Man-Induced Vibrations

DEFF Research Database (Denmark)

Jönsson, Jeppe; Hansen, Lars Pilegaard

1994-01-01

work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...

The efficacy of airflow and seat vibration on reducing visually induced motion sickness.

Science.gov (United States)

D'Amour, Sarah; Bos, Jelte E; Keshavarz, Behrang

2017-09-01

Visually induced motion sickness (VIMS) is a well-known sensation in virtual environments and simulators, typically characterized by a variety of symptoms such as pallor, sweating, dizziness, fatigue, and/or nausea. Numerous methods to reduce VIMS have been previously introduced; however, a reliable countermeasure is still missing. In the present study, the effect of airflow and seat vibration to alleviate VIMS was investigated. Eighty-two participants were randomly assigned to one of four groups (airflow, vibration, combined airflow and vibration, and control) and then exposed to a 15 min long video of a bicycle ride shot from first-person view. VIMS was measured using the Fast Motion Sickness Scale (FMS) and the Simulator Sickness Questionnaire (SSQ). Results showed that the exposure of airflow significantly reduced VIMS, whereas the presence of seat vibration, in contrast, did not have an impact on VIMS. Additionally, we found that females reported higher FMS scores than males, however, this sex difference was not found in the SSQ scores. Our findings demonstrate that airflow can be an effective and easy-to-apply technique to reduce VIMS in virtual environments and simulators, while vibration applied to the seat is not a successful method.

Vibrational emission analysis of the CN molecules in laser-induced breakdown spectroscopy of organic compounds

Energy Technology Data Exchange (ETDEWEB)

Fernández-Bravo, Ángel; Delgado, Tomás; Lucena, Patricia; Laserna, J. Javier, E-mail: laserna@uma.es

2013-11-01

Laser-induced breakdown spectroscopy (LIBS) of organic materials is based on the analysis of atomic and ionic emission lines and on a few molecular bands, the most important being the CN violet system and the C{sub 2} Swan system. This paper is focused in molecular emission of LIBS plasmas based on the CN (B{sup 2}Σ–X{sup 2}Σ) band, one of the strongest emissions appearing in all carbon materials when analyzed in air atmosphere. An analysis of this band with sufficient spectral resolution provides a great deal of information on the molecule, which has revealed that valuable information can be obtained from the plume chemistry and dynamics affecting the excitation mechanisms of the molecules. The vibrational emission of this molecular band has been investigated to establish the dependence of this emission on the molecular structure of the materials. The paper shows that excitation/emission phenomena of molecular species observed in the plume depend strongly on the time interval selected and on the irradiance deposited on the sample surface. Precise time resolved LIBS measurements are needed for the observation of distinctive CN emission. For the organic compounds studied, larger differences in the behavior of the vibrational emission occur at early stages after plasma ignition. Since molecular emission is generally more complex than that involving atomic emission, local plasma conditions as well as plume chemistry may induce changes in vibrational emission of molecules. As a consequence, alterations in the distribution of the emissions occur in terms of relative intensities, being sensitive to the molecular structure of every single material. - Highlights: • Vibrational emission of CN species in laser-induced plasmas has been investigated. • Distribution of vibrational emission of CN has been found to be time dependent. • Laser irradiance affects the vibrational distribution of the CN molecules. • Plume chemistry controls the excitation mechanisms of CN

Improving hand sensibility in vibration induced neuropathy: A case-series

Directory of Open Access Journals (Sweden)

Lundborg Göran

2011-04-01

Full Text Available Abstract Objectives We report a long-term series of nine workers suffering from vibration-induced neuropathy, after many years of exposure to hand-held vibrating tools at high or low frequency. They were treated with temporary selective cutaneous anaesthesia (EMLA® cream of the forearm repeatedly for a period up to one year (in two cases four years. The aim was to improve their capacity to perceive touch and thereby improve hand function and diminish disability. The treatment principle is based on current concepts of brain plasticity, where a deafferentation of a skin area results in improved sensory function in adjacent skin areas. Methods All participants had sensory hand problems in terms of numbness (median touch thresholds > 70 mg and impaired hand function influencing ADL (mean DASH score 22. After an initial identical self-administered treatment period of 8 weeks (12-15 treatments with increasing intervals they did one treatment every 2-3 month. Results After one year sensibility (touch thresholds and tactile discrimination as well as hand function (mean DASH score 13 were improved in a majority of the cases. Seven of the participants choose to continue the treatment after the first year and two of them have continued at a regular basis for up to four years. A surprising, secondary finding was diminishing nocturnal numbness of the hand and arm in eight of the nine subjects from "frequently" to "hardly ever or never". Conclusions Our observations open new perspectives for treatment of impaired sensibility and hand function in a group of patients with vibration induced hand problems where we have no treatment to offer today.

Friction-induced vibrations and self-organization mechanics and non-equilibrium thermodynamics of sliding contact

CERN Document Server

Nosonovsky, Michael

2013-01-01

Many scientists and engineers do not realize that, under certain conditions, friction can lead to the formation of new structures at the interface, including in situ tribofilms and various patterns. In turn, these structures-usually formed by destabilization of the stationary sliding regime-can lead to the reduction of friction and wear. Friction-Induced Vibrations and Self-Organization: Mechanics and Non-Equilibrium Thermodynamics of Sliding Contact combines the mechanical and thermodynamic methods in tribology, thus extending the field of mechanical friction-induced vibrations to non-mechanical instabilities and self-organization processes at the frictional interface. The book also relates friction-induced self-organization to novel biomimetic materials, such as self-lubricating, self-cleaning, and self-healing materials. Explore Friction from a Different Angle-as a Fundamental Force of Nature The book begins with an exploration of friction as a fundamental force of nature throughout the history of science....

Wave-induced Ship Hull Vibrations in Stochastic Seaways

DEFF Research Database (Denmark)

Jensen, Jørgen Juncher; Dogliani, M.

1996-01-01

A theoretical Study is undertaken on the determination of wave-induced loads in flexible ship hulls. The calculations are performed within the framework of a non-linear, quadratic strip theory formulated in the frequency domain. Included are non-linear effects due to changes in added mass......, hydrodynamic damping and water line breadth with sectional immersion in waves. The study is limited to continuous excitations from the waves and thus transient so-called whipping vibrations due to slamming loads are not considered.Because of the non-linearities the ship hull responses become non...... to the large separation between dominating wave frequencies and the lowest two-node frequency of the hull beam. Both extreme value predictions and fatigue damage are considered.For a fast container ship the rigid body and two-node (springing) vertical wave-induced bending moments amidship are calculated...

Leakage flow-induced vibrations for variations of a tube-in-tube slip joint

International Nuclear Information System (INIS)

Mulcahy, T.M.

1986-01-01

Variations in the design of a specific slip joint separating two cantilevered, telescoping tubes conveying water were studied to determine their effect upon the leakage flow-induced vibration self-excitation mechanism known to exist for the original slip joint geometry. The important parameters controlling the self-excitation mechanism were identified, which, along with previous results, allowed the determination of a comprehensive set of design rules to avoid unstable vibrations. This was possible even though a new self-excitation mechanism was found when the engagement of the two tubes was small. 9 refs

Sensory training with vibration-induced kinesthetic illusions improves proprioceptive integration in patients with Parkinson's disease.

Science.gov (United States)

Ribot-Ciscar, Edith; Aimonetti, Jean-Marc; Azulay, Jean-Philippe

2017-12-15

The present study investigates whether proprioceptive training, based on kinesthetic illusions, can help in re-educating the processing of muscle proprioceptive input, which is impaired in patients with Parkinson's disease (PD). The processing of proprioceptive input before and after training was evaluated by determining the error in the amplitude of voluntary dorsiflexion ankle movement (20°), induced by applying a vibration on the tendon of the gastrocnemius-soleus muscle (a vibration-induced movement error). The training consisted of the subjects focusing their attention upon a series of illusory movements of the ankle. Eleven PD patients and eleven age-matched control subjects were tested. Before training, vibration reduced dorsiflexion amplitude in controls by 4.3° (Pkinesthetic illusions, is a simple means for re-educating the processing of muscle proprioceptive input in PD patients. Such complementary training should be included in rehabilitation programs that presently focus on improving balance and motor performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Regarding "A new method for predicting nonlinear structural vibrations induced by ground impact loading" [Journal of Sound and Vibration, 331/9 (2012) 2129-2140

Science.gov (United States)

Cartmell, Matthew P.

2016-09-01

The Editor wishes to make the reader aware that the paper "A new method for predicting nonlinear structural vibrations induced by ground impact loading" by Jun Liu, Yu Zhang, Bin Yun, Journal of Sound and Vibration, 331 (2012) 2129-2140, did not contain a direct citation of the fundamental and original work in this field by Dr. Mark Svinkin. The Editor regrets that this omission was not noted at the time that the above paper was accepted and published.

Impact of scalp cooling on chemotherapy-induced alopecia, wig use and hair growth of patients with cancer

NARCIS (Netherlands)

van den Hurk, C.J.; van den Akker-van Marle, E.M.; Breed, W.P.M.; van de Poll-Franse, L.V.; Nortier, J.; Coebergh, J.W.W.

2013-01-01

Introduction Cytotoxic therapy for patients with cancer frequently induces reversible, but long-lasting alopecia which might be prevented by scalp cooling. This study evaluates the effectiveness of scalp cooling with respect to the severity of chemotherapy-induced alopecia (CIA) and the purchase and

Understanding of bridge cable vibrations and the associate flow-field through the full-scale monitoring of vibrations and Wind

DEFF Research Database (Denmark)

Acampora, Antonio

This dissertation investigates the conditions that promote rain-wind-induced vibrations of inclined cable on cable-stayed bridges. Rain-wind-induced vibrations are known as the most common type of cable vibrations and capable of severe vibrations. The recent increase in the number of cable stayed...... bridges continuously becoming longer and lighter have resulted in a high number of observations of cable vibrations. A theoretical background for the tool used in this work is presented in terms of cables vibrations mechanisms, aerodynamic damping and system identification techniques. A detailed...... literature review of reported observations of rain-wind-induced cable vibrations of fullscale bridges is shown. The database of observed events on bridges collects information about the conditions that likely develop the phenomenon, together with the means used to suppress or reduce the occurrence of cable...

Modeling fluid forces and response of a tube bundle in cross-flow induced vibrations

International Nuclear Information System (INIS)

Khushnood, Shahab; Khan, Zaffar M.; Malik, M. Afzaal; Koreshi, Zafarullah; Khan, Mahmood Anwar

2003-01-01

Flow induced vibrations occur in process heat exchangers, condensers, boilers and nuclear steam generators. Under certain flow conditions and fluid velocities, the fluid forces result in tube vibrations and possible damage of tube, tube sheet or baffle due to fretting and fatigue. Prediction of these forces is an important consideration. The characteristics of vibration depend greatly on the fluid dynamic forces and structure of the tube bundle. It is undesirable for the tube bundles to vibrate excessively under normal operating conditions because tubes wear and eventual leakage can occur leading to costly shutdowns. In this paper modeling of fluid forces and vibration response of a tube in a heat exchanger bundle has been carried out. Experimental validation has been performed on an existing refinery heat exchanger tube bundle. The target tube has been instrumented with an accelerometer and strain gages. The bundle has been studied for pulse, sinusoidal and random excitations. Natural frequencies and damping of the tubes have also been computed. Experimental fluid forces and response shows a reasonable agreement with the predictions. (author)

Process of Equiaxed Grains of RE-Al Alloy under Slope Vibration

International Nuclear Information System (INIS)

Xie Shikun; Yi Rongxi; Pan Xiaoliang; Zheng Xiaoqiu; Guo Xiuyan

2010-01-01

A new technique using slope vibration casting process during heating and isothermal holding period to prepare Al-7Si-2RE alloy has been studied. The small, near-spherical and non-dendritic microstructure with the semi-solid processing requirements has been obtained. Experiments show that the cooling method, pouring process and the convection of melt caused by slope vibration had significant effects on the formation of near-spherical primary gains. The water-cooled copper mold casting with slope vibration at the temperature near liquidus can obtain Al-7Si-2RE alloy with small homogeneous equiaxed grains, the average grain diameter is 48.3 μm, and the average grain roundness is 1.92.

Effect of shelf aging on vibration transmissibility of anti-vibration gloves

Science.gov (United States)

SHIBATA, Nobuyuki

2017-01-01

Anti-vibration gloves have been used in real workplaces to reduce vibration transmitted through hand-held power tools to the hand. Generally materials used for vibration attenuation in gloves are resilient materials composed of certain synthetic and/or composite polymers. The mechanical characteristics of the resilient materials used in anti-vibration gloves are prone to be influenced by environmental conditions such as temperature, humidity, and photo-irradiation, which cause material degradation and aging. This study focused on the influence of shelf aging on the vibration attenuation performance of air-packaged anti-vibration gloves following 2 yr of shelf aging. Effects of shelf aging on the vibration attenuation performance of anti-vibration gloves were examined according to the Japan industrial standard JIS T8114 test protocol. The findings indicate that shelf aging induces the reduction of vibration attenuation performance in air-packaged anti-vibration gloves. PMID:28978817

Nonlinear Dynamic Analysis on the Rain-Wind-Induced Vibration of Cable Considering the Equilibrium Position of Rivulet

Directory of Open Access Journals (Sweden)

Xijun Liu

2013-01-01

Full Text Available The nonlinear dynamic behavior of rain-wind-induced vibration of inclined cable is investigated with the consideration of the equilibrium position of the moving rivulet. The partial differential governing equations of three-degree-of-freedom on the model of rain-wind-induced cable vibration are established, which are proposed for describing the nonlinear interactions among the in-plane, out-of-plane vibration of the cable and the oscillation of the moving rivulet. The Galerkin method is applied to discretize the partial differential governing equations. The approximately analytic solution is obtained by using the method of averaging. The unique correspondence between the wind and the equilibrium position of the rivulet is ascertained. The presence of rivulet at certain positions on the surface of cable is then proved to be one of the trigger for wind-rain-induced cable vibration. The nonlinear dynamic phenomena of the inclined cable subjected to wind and rain turbulence are then studied by varying the parameters including mean wind velocity, Coulomb damping force, damping ratio, the span length, and the initial tension of the inclined cable on the model. The jump phenomenon is also observed which occurs when there are multiple solutions in the system.

Wind-induced cable vibrations and countermeasures of cables of PC cable-stayed bridge. PC syachokyo keburu no kaze ni yoru shindo to sono taisaku

Energy Technology Data Exchange (ETDEWEB)

Yoneda, M. (Kawada Industries Inc., Tokyo (Japan))

1994-05-01

In recent years, long span of cable-stayed bridges is remarkable. The wind-induced cable vibration called as line vibration and wake galloping was given as an important problem not only in the steel cable-stayed bridges but also in the PC cable-stayed bridges. The technical engineers in design of the cable-stayed bridges have many times to confront the problems on the vibration control of cables, it is considered that sufficient understand of the wind-induced vibration and countermeasures for cables of the PC cable-stayed bridges is necessary. Many reports on the countermeasure examples and trend of vibration control centred on cables of the cable-stayed bridges have been published. In this paper, the wind-induced vibration of cables in the cable-stayed bridges was reviewed, the examples of countermeasures of vibration control on cables in the PC cable-stayed bridges was mainly introduced. The remaining tasks and future prospects on vibration control of the PC cable-stayed bridges were described. 14 refs., 13 figs., 4 tabs.

Preventive measures against vibration of FBR reactor vessel cooling structure

International Nuclear Information System (INIS)

Eguchi, Yuzuru; Tanaka, Nobukazu

1989-01-01

The present paper describes the fundamental feature of the fluid-elastic vibration of flexible overflow weir, as observed in the French demonstration fast breeder reactor, Super Phenix-1. In the experimental study, the instability criterion of the fluid-elastic vibration was studied by using a simple experimental apparatus of a rectangular tank separated by a flexible weir. A spring-mass model was developed to clarify the mechanism of the instability. The instability condition was analytically derived from the equations of the spring-mass model. The equations of the spring-mass model was also computationally integrated in time to simulate the temporal evolution of the fluid-elastic vibration. The comparison between the experimental and theoretical results indicates that the present theoretical model is capable of predicting most of the physical tendencies observed in the experiment. The present study revealed that the lag time of waterfall at the weir is the most influential parameter among other hydro-elastic parameters. (author)

Cooling reduces the cutaneous afferent firing response to vibratory stimuli in glabrous skin of the human foot sole.

Science.gov (United States)

Lowrey, Catherine R; Strzalkowski, Nicholas D J; Bent, Leah R

2013-02-01

Skin on the foot sole plays an important role in postural control. Cooling the skin of the foot is often used to induce anesthesia to determine the role of skin in motor and balance control. The effect of cooling on the four classes of mechanoreceptor in the skin is largely unknown, and thus the aim of the present study was to characterize the effects of cooling on individual skin receptors in the foot sole. Such insight will better isolate individual receptor contributions to balance control. Using microneurography, we recorded 39 single nerve afferents innervating mechanoreceptors in the skin of the foot sole in humans. Afferents were identified as fast-adapting (FA) or slowly adapting (SA) type I or II (FA I n = 16, FA II n = 7, SA I n = 6, SA II n = 11). Receptor response to vibration was compared before and after cooling of the receptive field (2-20 min). Overall, firing response was abolished in 30% of all receptors, and this was equally distributed across receptor type (P = 0.69). Longer cooling times were more likely to reduce firing response below 50% of baseline; however, some afferent responses were abolished with shorter cooling times (2-5 min). Skin temperature was not a reliable indicator of the level of receptor activation and often became uncoupled from receptor response levels, suggesting caution in the use of this parameter as an indicator of anesthesia. When cooled, receptors preferentially coded lower frequencies in response to vibration. In response to a sustained indentation, SA receptors responded more like FA receptors, primarily coding "on-off" events.

Advancements in flow-induced vibration research and design criteria

International Nuclear Information System (INIS)

Pettigrew, M.J.

2009-01-01

Two-phase flow exists in many nuclear components and, in particular, steam generators. So far relatively little research work has been done on two-phase flow-induced vibration probably because it is difficult to do. Two-phase flows are not homogeneous and are governed by an additional parameter called void fraction. This can lead to different flow patterns or regimes that can change completely the vibration behaviour. Fluidelastic instability, random turbulence excitation and detailed flow characteristics are being investigated in tube bundles subjected to two-phase cross flow. Fluidelastic instability of a tube bundle preferentially flexible in the flow direction was observed probably for the first time. This is particularly relevant to the problem of in-plane vibration of nuclear steam generator U-tubes and has resulted in changes in our design criteria. Unexpected quasi-periodic excitation forces were also measured in the tube bundle. These are attributed to an alternating wake in the lift direction and to fluctuating momentum flux in the drag direction. Vibration damping due to two-phase flow is very dependent on void fraction and appears directly related to the interface surface area between phases. Maximum damping values correspond to the transitions between flow regimes. Fibre optic probes were developed to measure the characteristics of two-phase flows. These probes are used to take detailed measurements in a triangular array of tubes in cross flow. The results show that the flow tends to stream between the tubes. These studies have yielded interesting results but have raised more questions that could lead to improved design criteria. The more puzzling results will be discussed in this presentation. Some of the dynamic phenomena will be illustrated by animation. (author)

Measuring the arterial-induced skin vibration by geometrical moiré fringe

Science.gov (United States)

Chiu, Shih-Yung; Wang, Chun-Hsiung; Lee, Shu-Sheng; Wu, Wen-Jong; Hsu, Yu-Hsiang; Lee, Chih-Kung

2018-02-01

The demand for self-measured blood pressure self-monitoring device has much increased due to cardiovascular diseases have become leading causes of death for aging population. Currently, the primary non-invasive blood pressure monitoring method is cuff-based. It is well developed and accurate. However, the measuring process is not comfortable, and it cannot provide a continuous measurement. To overcome this problem, methods such as tonometry, volume clamp method, photoplethysmography, pulse wave velocity, and pulse transit time are reported. However, the limited accuracy hindered its application for diagnostics. To perform sequential blood pressure measurement with a high accuracy and long-term examination, we apply moiré interferometry to measure wrist skin vibration induced by radial artery. To achieve this goal, we developed a miniaturized device that can perform moiré interferometry around the wrist region. The 0.4-mm-pitched binary grating and tattoo sticker with 0.46 mm-pitched stripe pattern are used to perform geometric moiré. We demonstrated that the sensitivity and accuracy of this integrated system were sufficient to monitor arterialinduced skin vibration non-invasively. Our developed system was validated with ECG signals collected by a commercial system. According to our studies from measurement, the repeatability of wrist pulsation measurement was achieved with an accuracy of 99.1% in heart rate. A good repeatability of wrist pulse measurement was achieved. Simulations and experiments are both conducted in this paper and prove of geometrical moiré method a suitable technique for arterial-induced skin vibration monitoring.

Flow induced vibration characteristics in 2X3 bundle critical heat flux experiment

International Nuclear Information System (INIS)

Kim, Dae Hun; Chang, Soon Heung

2005-01-01

Above a certain heat flux, the liquid can no longer permanently wet the heater surface. This situation leads to an inordinate decrease in the surface heat transfer. This heat flux is commonly referred to as the critical heat flux (CHF). The CHF in nuclear reactors is one of the important thermal hydraulic parameters limiting the available power. Flow induced vibration (FIV) is the vibration caused by a fluid flowing around a body. In the fluid flowing system, FIV occurred by structures and flow condition. Many structures in nuclear power plant system are designed to prevent from structure failure due to FIV. Recently, Hibiki and Ishii (1998) carried out an experimental investigation on the effect of flow-induced vibration (FIV) on two-phase flow structure in vertical tube and reported that the FIV drastically changed the void fraction profiles. The void fraction profiles is one of the important parameter for determining CHF. Therefore, the investigation on the effect of FIV on CHF are needed. The research on FIV characteristics detection during CHF experiment in 2X3 bundle using R-134a has been carried out in KAIST. Using the results new FIV correlation in 2-pahse turbulent flow are suggested after finding out relation between CHF and dynamic pressure fluctuation value

Flow-induced vibration test of an advanced water reactor model. Pt. 1. Turbulence-induced forcing function

International Nuclear Information System (INIS)

Au-Yang, M.K.; Brenneman, B.; Raj, D.

1995-01-01

A 1:9 scale model of a proposed advanced water reactor was tested for flow-induced vibration. The main objectives of this test were: (1) to derive an empirical equation for the turbulence forcing function which can be applied to the full-sized prototype; (2) to study the effect of viscosity on the turbulence; (3) to verify the ''superposition'' assumption widely used in dynamic analysis of weakly coupled fluid-shell systems; and (4) to measure the shell responses to verify methods and computer programs used in the flow-induced vibration analysis of the prototype. This paper describes objectives (1), (2), and (3); objective (4) will be discussed in a companion paper.The turbulence-induced fluctuating pressure was measured at 49 locations over the surface of a thick-walled, non-responsive scale model of the reactor vessel/core support cylinders. An empirical equation relating the fluctuating pressure, the frequency, and the distance from the inlet nozzle center line was derived to fit the test data. This equation involves only non-dimensional, fluid mechanical parameters that are postulated to represent the full-sized, geometrically similar prototype. While this postulate cannot be verified until similar measurements are taken on the full-sized unit, a similar approach using a 1:6 scale model of a commercial pressurized water reactor was verified in the mid-1970s by field measurements on the full-sized reactor. (orig.)

Effect of cooling water on stability of NLC linac components

Energy Technology Data Exchange (ETDEWEB)

F. Le Pimpec et al.

2003-02-11

Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structures and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. A design, incorporating the proper decoupling of structure vibrations from the linac quadrupoles, is being pursued.

Effect of Cooling Water on Stability of NLC Linac Components

Energy Technology Data Exchange (ETDEWEB)

Le Pimpec, Frederic

2002-11-01

Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structures and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. A design, incorporating the proper decoupling of structure vibrations from the linac quadrupoles, is being pursued.

Vibrationally coupled electron transport through single-molecule junctions

Energy Technology Data Exchange (ETDEWEB)

Haertle, Rainer

2012-04-26

vibrational effects have a profound influence on the transport characteristics of a single-molecule contact and play therefore a fundamental role in this transport problem. Our findings demonstrate that vibrationally coupled electron transport through a molecular junction involves two types of processes: (i) transport processes, where an electron tunnels through the molecular bridge from one lead to the other, and (ii) electron-hole pair creation processes, where an electron tunnels from one of the leads onto the molecular bridge and back to the same lead again. Transport processes directly contribute to the electrical current flowing through a molecular contact and involve both excitation and deexcitation processes of the vibrational modes of the junction. Electron-hole pair creation processes do not directly contribute to the electrical current and typically involve only deexcitation processes. Nevertheless, they constitute a cooling mechanism for the vibrational modes of a single-molecule junction that is as important as cooling by transport processes. As the level of vibrational excitation determines the efficiency of electron transport processes, they have an indirect influence on the electrical current flowing through the junction. As we show, however, this influence can be substantial, in particular, if the molecule is coupled asymmetrically to the leads. Accounting for all these processes and their complex interrelationship, we analyze a number of intriguing transport phenomena, including rectification, negative differential resistance, anomalous peak broadening, mode-selective vibrational excitation and vibrationally induced decoherence. Moreover, we show that higher levels of vibrational excitation are obtained for weaker electronic-vibrational coupling. Thus, based on physical grounds, we establish a relation between the weak electronic-vibrational coupling limit and the limit of large bias voltages, where the level of vibrational excitation in a molecular junction

Proceedings of the 8. international conference on Flow-induced vibration

International Nuclear Information System (INIS)

Langre, E. de; Axisa, F.

2004-01-01

FIV2004, the eighth of the series of International Conferences on Flow-Induced Vibration initiated at Keswick in 1973, evidences the sustained interest of the scientific and engineering international community for a subject area which incorporates at least two major disciplines: fluid mechanics and structural dynamics. Flow induced vibration (FIV) occur whenever a structure is in contact with a flowing fluid; which is a very common occurrence indeed. FIV can be rightly perceived as very useful and agreeable, in musical instruments, or at the opposite as annoying and even disastrous, in mechanical engineering. In both cases, the subject motivates a large and highly diversified amount of research work, driven either by scientific curiosity or engineering concerns, or both. In this field, empirical knowledge and experience are a precious asset but a certain breadth of perspective gained through a thorough background in theoretical mechanics is also necessary. In other words, to deal successfully with FIV problems, theoretical and pragmatic knowledge must be skillfully interwoven. Having also in mind the impressive progress achieved since the early seventies both in experimental techniques and computer science, it is rather fascinating to realize that we have still to learn so much about so 'elementary' systems as a pipe conveying air or water, or cylindrical rods subjected to cross-flow, to mention just two archetypical systems which are in fact extremely complex and which motivated so many studies already at the time of the first Keswick Conference and which still do at FIV2004. Though such systems are encountered in many industrial components and are rather easily accessible to experiment, they still give rise to many challenging questions concerning the extremely varied dynamical behavior they can display, which remain often insufficiently amenable to prediction. By no means this is to say that the research work devoted to FIV up to now has been made in vain. First

Study on the Effect and Mechanism of Aerodynamic Measures for the Vortex-Induced Vibration of Separate Pairs of Box Girders in Cable-Stayed Bridges

Directory of Open Access Journals (Sweden)

Han Xin He

2015-01-01

Full Text Available Although not always resulting in catastrophic failures, vortex-induced vibration (VIV response can seriously impact the fatigue life and functionality of bridges, especially for separate pairs of box girders in cable-stayed bridges. This study investigates the effects of three aerodynamic measures: grating, inclined web plate, and the baffles on separated box girders in the cable-stayed bridges. The experimental result indicates that the grating of different opening ratios can control the vortex-induced vibration effectively, and the optimized grating opening ratio set in this paper is 40%. Increasing the angle of inclined web plate has a great control on mitigation of the vortex-induced vibration. However, there is an optimum angle where the amplitude of vortex-induced vibration is the smallest at low wind speed. The amplitude of vortex-induced vibration becomes larger with the increase of the web inclined angle that exceeds the optimum angle. Comparatively, the baffles installed on both sides of the inclined webs are more effective to restrain the vortex-induced resonance. The Computational Fluent Dynamics (CFD software is utilized to investigate the mechanism of the experimental results.

Dynamic analysis of cooling towers

International Nuclear Information System (INIS)

Bittnar, Z.

1987-01-01

Natural draught cooling towers are shell structures subjected to random vibrations due to wind turbulence and earthquake. The need of big power plant units has initiated the design of very large cooling towers. The random response of such structures may be analysed using a spectral approach and assuming a linear behaviour of the structure. As the modal superposition method is the most suitable procedure for this purpose it is necessary to determine the natural frequencies and mode shapes with adequate accuracy. (orig./GL)

Predicting wind-induced vibrations of high-rise buildings using unsteady CFD and modal analysis

KAUST Repository

Zhang, Yue; Habashi, Wagdi G (Ed); Khurram, Rooh Ul Amin

2015-01-01

This paper investigates the wind-induced vibration of the CAARC standard tall building model, via unsteady Computational Fluid Dynamics (CFD) and a structural modal analysis. In this numerical procedure, the natural unsteady wind in the atmospheric

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

Science.gov (United States)

Zhu, Jin; Zhang, Wei

2015-04-01

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

Simulation of vibration-induced effect on plasma current measurement using a fiber optic current sensor.

Science.gov (United States)

Descamps, Frédéric; Aerssens, Matthieu; Gusarov, Andrei; Mégret, Patrice; Massaut, Vincent; Wuilpart, Marc

2014-06-16

An accurate measurement of the plasma current is of paramount importance for controlling the plasma magnetic equilibrium in tokamaks. Fiber optic current sensor (FOCS) technology is expected to be implemented to perform this task in ITER. However, during ITER operation, the vessel and the sensing fiber will be subject to vibrations and thus to time-dependent parasitic birefringence, which may significantly compromise the FOCS performance. In this paper we investigate the effects of vibrations on the plasma current measurement accuracy under ITER-relevant conditions. The simulation results show that in the case of a FOCS reflection scheme including a spun fiber and a Faraday mirror, the error induced by the vibrations is acceptable regarding the ITER current diagnostics requirements.

Processes setting the characteristics of sea surface cooling induced by tropical cyclones

OpenAIRE

Vincent, E.M.; Lengaigne, Matthieu; Madec, G.; Vialard, Jérôme; Samson, G.; Jourdain, N.C.; Menkès, Christophe; Jullien, S.

2012-01-01

A 1/2 degrees resolution global ocean general circulation model is used to investigate the processes controlling sea surface cooling in the wake of tropical cyclones (TCs). Wind forcing related to more than 3000 TCs occurring during the 1978-2007 period is blended with the CORE II interannual forcing, using an idealized TC wind pattern with observed magnitude and track. The amplitude and spatial characteristics of the TC-induced cooling are consistent with satellite observations, with an aver...

On the neutron noise diagnostics of pressurized water reactor control rod vibrations II. Stochastic vibrations

International Nuclear Information System (INIS)

Pazsit, I.; Glockler, O.

1984-01-01

In an earlier publication, using the theory of neutron fluctuations induced by a vibrating control rod, a complete formal solution of rod vibration diagnostics based on neutron noise measurements was given in terms of Fourier-transformed neutron detector time signals. The suggested procedure was checked in numerical simulation tests where only periodic vibrations could be considered. The procedure and its numerical testing are elaborated for stochastic two-dimensional vibrations. A simple stochastic theory of two-dimensional flow-induced vibrations is given; then the diagnostic method is formulated in the stochastic case, that is, in terms of neutron detector auto- and crosspower spectra. A previously suggested approximate rod localization technique is also formulated in the stochastic case. Applicability of the methods is then investigated in numerical simulation tests, using the proposed model of stochastic two-dimensional vibrations when generating neutron detector spectra that simulate measured data

Modeling skin cooling using optical windows and cryogens during laser induced hyperthermia in a multilayer vascularized tissue

International Nuclear Information System (INIS)

Singh, Rupesh; Das, Koushik; Okajima, Junnosuke; Maruyama, Shigenao; Mishra, Subhash C.

2015-01-01

This article deals with the spatial and the temporal evolution of tissue temperature during skin surface cooled laser induced hyperthermia. Three different skin surface cooling methodologies viz., optical window contact cooling, cryogenic spray cooling and cryogen cooled optical window contact cooling are considered. Sapphire, yttrium aluminum garnet, lithium tantalate, and magnesium oxide doped lithium niobate are the considered optical windows. The cryogens considered are liquid CO_2 and R1234yf. Heat transfer in the multilayer skin tissue embedded with thermally significant blood vessels pairs is modeled using the Pennes and Weinbaum–Jiji bioheat equations. Weinbaum–Jiji bioheat equation is used for the vascularized tissue. Laser transport in the tissue is modeled using the radiative transfer equation. Axial and radial (skin surface) temperature distributions for different combinations of optical windows and cryogens are analyzed. Liquid CO_2 cooled yttrium aluminum garnet is found to be the best surface cooling mechanism. - Highlights: • Skin surface cooled laser induced hyperthermia is studied. • A multi-layer 2-D cylindrical tissue geometry is considered. • Both Pennes and Weinbaum–Jiji bioheat models are considered. • Laser transport in the tissue is modeled using discrete ordinate method. • Results for 4 optical windows and 2 cryogens for skin cooling are presented.

High Energy Vibration for Gas Piping

Science.gov (United States)

Lee, Gary Y. H.; Chan, K. B.; Lee, Aylwin Y. S.; Jia, ShengXiang

2017-07-01

In September 2016, a gas compressor in offshore Sarawak has its rotor changed out. Prior to this change-out, pipe vibration study was carried-out by the project team to evaluate any potential high energy pipe vibration problems at the compressor’s existing relief valve downstream pipes due to process condition changes after rotor change out. This paper covers high frequency acoustic excitation (HFAE) vibration also known as acoustic induced vibration (AIV) study and discusses detailed methodologies as a companion to the Energy Institute Guidelines for the avoidance of vibration induced fatigue failure, which is a common industry practice to assess and mitigate for AIV induced fatigue failure. Such detailed theoretical studies can help to minimize or totally avoid physical pipe modification, leading to reduce offshore plant shutdown days to plant shutdowns only being required to accommodate gas compressor upgrades, reducing cost without compromising process safety.

Flow-induced vibration of steam generator helical tubes subjected to external liquid cross flow and internal two-phase flow

International Nuclear Information System (INIS)

Jong Chull Jo; Myung Jo Jhung; Woong Sik Kim; Hho Jung Kim

2005-01-01

Full text of publication follows: This paper addresses the potential flow-induced vibration problems in a helically-coiled tube steam generator of integral-type nuclear reactor, of which the tubes are subjected to liquid cross flow externally and multi-phase flow externally. The thermal-hydraulic conditions of both tube side and shell side flow fields are predicted using a general purpose computational fluid dynamics code employing the finite volume element modeling. To get the natural frequency and corresponding mode shape of the helical type tubes with various conditions, a finite element analysis code is used. Based on the results of both helical coiled tube steam generator thermal-hydraulic and coiled tube modal analyses, turbulence-induced vibration and fluid-elastic instability analyses are performed. And then the potential for damages on the tubes due to either turbulence-induced vibration or fluid-elastic instability is assessed. In the assessment, special emphases are put on the detailed investigation for the effects of support conditions, coil diameter, and helix pitch on the modal, vibration amplitude and instability characteristics of tubes, from which a technical information and basis needed for designers and regulatory reviewers can be derived. (authors)

Two-phase flow induced vibrations in CANDU steam generators

International Nuclear Information System (INIS)

Gidi, A.

2009-01-01

The U-Bend region of nuclear steam generators tube bundles have suffered from two-phase cross flow induced vibrations. Tubes in this region have experienced high amplitude vibrations leading to catastrophic failures. Turbulent buffeting and fluid-elastic instability has been identified as the main causes. Previous investigations have focused on flow regime and two-phase flow damping ratio. However, tube bundles in steam generators have vapour generated on the surface of the tubes, which might affect the flow regime, void fraction distribution, turbulent intensity levels and tube-flow interaction, all of which have the potential to change the tube vibration response. A cantilevered tube bundle made of electric cartridges heaters was built and tested in a Freon-11 flow loop at McMaster University. Tubes were arranged in a parallel triangular configuration. The bundle was exposed to two-phase cross flows consisting of different combinations of void from two sources, void generated upstream of the bundle and void generated at the surface of the tubes. Tube tip vibration response was measured optically and void fraction was measured by gamma densitometry technique. It was found that tube vibration amplitude in the transverse direction was reduced by a factor of eight for void fraction generated at the tube surfaces only, when compared to the upstream only void generation case. The main explanation for this effect is a reduction in the correlation length of the turbulent buffeting forcing function. Theoretical calculations of the tube vibration response due to turbulent buffeting under the same experimental conditions predicted a similar reduction in tube amplitude. The void fraction for the fluid-elastic instability threshold in the presence of tube bundle void fraction generation was higher than that for the upstream void fraction generation case. The first explanation of this difference is the level of turbulent buffeting forces the tube bundle was exposed to

Muscle-Cooling Intervention to Reduce Fatigue and Fatigue-Induced Tremor in Novice and Experienced Surgeons: A Preliminary Investigation

OpenAIRE

Jensen, Lauren; Dancisak, Michael; Korndorffer, James

2016-01-01

A localized, intermittent muscle-cooling protocol was implemented to determine cooling garment efficacy in reducing upper extremity muscular fatigue and tremor in novice ( n  = 10) and experienced surgeons ( n  = 9). Subjects wore a muscle-cooling garment while performing multiple trials of a forearm exercise and paired suturing task to induce muscular fatigue and exercise-induced tremor. A reduction in tremor amplitude and an extension in time to fatigue were expected with muscle...

Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation

Science.gov (United States)

Miyamoto, Yuki; Hara, Hideaki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

2018-01-01

We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 μm with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 μm. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.

A study on the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise

Directory of Open Access Journals (Sweden)

Yukio Takahashi

2011-01-01

Full Text Available To investigate the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise, we conducted two experiments. In Experiment 1, eight male subjects were exposed to seven types of low-frequency noise stimuli: two pure tones [a 31.5-Hz, 100-dB(SPL tone and a 50-Hz, 100-dB(SPL tone] and five complex noises composed of the pure tones. For the complex noise stimuli, the sound pressure level of one tonal component was 100 dB(SPL and that of another one was either 90, 95, or 100 dB(SPL. Vibration induced on the body surface was measured at five locations, and the correlation with the subjective rating of the vibratory sensation at each site of measurement was examined. In Experiment 2, the correlation between the body surface vibration and the vibratory sensation was similarly examined using seven types of noise stimuli composed of a 25-Hz tone and a 50-Hz tone. In both the experiments, we found that at the chest and the abdomen, the rating of the vibratory sensation was in close correlation with the vibration acceleration level (VAL of the body surface vibration measured at each corresponding location. This was consistent with our previous results and suggested that at the trunk of the body (the chest and the abdomen, the mechanoreception of body vibrations plays an important role in the experience of the vibratory sensation in persons exposed to high-level low-frequency noise. At the head, however, no close correlation was found between the rating of the vibratory sensation and the VAL of body surface vibration. This suggested that at the head, the perceptual mechanisms of vibration induced by high-level low-frequency noise were different from those in the trunk of the body.

Cryotherapy-Induced Persistent Vasoconstriction After Cutaneous Cooling: Hysteresis Between Skin Temperature and Blood Perfusion

Science.gov (United States)

Khoshnevis, Sepideh; Craik, Natalie K.; Matthew Brothers, R.; Diller, Kenneth R.

2016-01-01

The goal of this study was to investigate the persistence of cold-induced vasoconstriction following cessation of active skin-surface cooling. This study demonstrates a hysteresis effect that develops between skin temperature and blood perfusion during the cooling and subsequent rewarming period. An Arctic Ice cryotherapy unit (CTU) was applied to the knee region of six healthy subjects for 60 min of active cooling followed by 120 min of passive rewarming. Multiple laser Doppler flowmetry perfusion probes were used to measure skin blood flow (expressed as cutaneous vascular conductance (CVC)). Skin surface cooling produced a significant reduction in CVC (P cryotherapy. PMID:26632263

Water flow simulation of the flow-induced vibration phenomenon of the thermowell in the prototype-FBR 'Monju'

International Nuclear Information System (INIS)

Anoda, Yoshinari; Kuroda, Takeshi; Kondo, Masaya; Murata, Hideo

1996-06-01

On December 8, 1995 a sodium leak event occurred in the secondary heat transport system (SHTS) of the prototype fast breeder reactor (FBR), Monju, owned and operated by the Power Reactor and Nuclear Fuel Development Corporation (PNC). The direct cause of the leak was a break of a thermowell installed in the loop piping of the SHTS. The break of the thermowell is now believed to have resulted from the flow-induced vibrations due to vortex shedding from the thermowell subjected to a crossflow of sodium. The Japan Atomic Energy Research Institute has conducted a series of water flow model experiments on the flow-induced vibrations of the thermowell to contribute to the post-factor analyses of the event conducted by the Investigation Taskforce on the Sodium Leak Accident in Monju which was established by the Science and Technology Agency (STA) after this event. The experiments were performed for a wide range of experimental conditions including the condition corresponding to the operating condition of the Monju's thermowell and showed the relationship between the vortex shedding pattern and the vibration mode as well as influence of the damping (stability) parameter on the amplitude of vibration. (author)

Vulnerability Assessment for a Complex Structure Using Vibration Response Induced by Impact Load

International Nuclear Information System (INIS)

Park, Jeongwon; Park, Junhong; Koo, Man Hoi

2014-01-01

This work presents a vulnerability assessment procedure for a complex structure using vibration characteristics. The structural behavior of a three-dimensional framed structure subjected to impact forces was predicted using the spectral element method. The Timoshenko beam function was applied to simulate the impact wave propagations induced by a high-velocity projectile at relatively high frequencies. The interactions at the joints were analyzed for both flexural and longitudinal wave propagations. Simulations of the impact energy transfer through the entire structure were performed using the transient displacement and acceleration responses obtained from the frequency analysis. The kill probabilities of the crucial components for an operating system were calculated as a function of the predicted acceleration amplitudes according to the acceptable vibration levels. Following the proposed vulnerability assessment procedure, the vulnerable positions of a three-dimensional combat vehicle with high possibilities of damage generation of components by impact loading were identified from the estimated vibration responses

Numerical investigations of two-degree-of-freedom vortex-induced vibration in shear flow

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hui; Liu, Mengke; Han, Yang; Li, Jian; Gui, Mingyue; Chen, Zhihua, E-mail: zhanghui1902@hotmail.com [Science and Technology on Transient Physics Laboratory, Nanjing University of Science and Technology, Nanjing 210094 (China)

2017-06-15

Exponential-polar coordinates attached to a moving cylinder are used to deduce the stream function-vorticity equations for two-degree-of-freedom vortex-induced vibration, the initial and boundary conditions, and the distribution of the hydrodynamic force, which consists of the vortex-induced force, inertial force, and viscous damping force. The fluid-structure interactions occurring from the motionless cylinder to the steady vibration are investigated numerically, and the variations of the flow field, pressure, lift/drag, and cylinder displacement are discussed. Both the dominant vortex and the cylinder shift, whose effects are opposite, affect the shear layer along the transverse direction and the secondary vortex along the streamwise direction. However, the effect of the cylinder shift is larger than that of the dominant vortices. Therefore, the former dominates the total effects of the flow field. Moreover, the symmetry of the flow field is broken with the increasing shear rate. With the effect of the background vortex, the upper vortices are strengthened, and the lower vortices are weakened; thus, the shear layer and the secondary vortices induced by the upper shedding vortices are strengthened, while the shear layer and the secondary vortices induced by the lower shedding vortices are weakened. Therefore, the amplitudes of the displacement and drag/lift dominated by the upper vortex are larger than those of the displacement and drag/lift dominated by the lower vortex. (paper)

Heat exchanger vibration

International Nuclear Information System (INIS)

Richards, D.J.W.

1977-01-01

The heat exchangers of various types are common items of plant in the generation and transmission of electricity. The amount of attention given to the flow-induced vibrations of heat exchangers by designers is usually related to the operational history of similar items of plant. Consequently, if a particular design procedure yields items of plant which behave in a satisfactory manner during their operational life, there is little incentive to improve or refine the design procedure. On the other hand, failures of heat exchangers clearly indicate deficiencies in the design procedures or in the data available to the designer. When such failures are attributable to flow-induced vibrations, the identification of the mechanisms involved is a prime importance. Ideally, basic research work provides the background understanding and the techniques necessary to be able to identify the important mechanisms. In practice, the investigation of a flow-induced vibration problem may identify the presence of mechanisms but may not be able to quantify their effects adequately. In these circumstances the need for additional work is established and the objectives of the research programme emerge. The purpose of this paper is to outline the background to the current research programme at C.E.R.L. on heat exchanger vibration

Heat exchanger vibration

Energy Technology Data Exchange (ETDEWEB)

Richards, D J.W. [CERL, CEGB, Leatherhead, Surrey (United Kingdom)

1977-12-01

The heat exchangers of various types are common items of plant in the generation and transmission of electricity. The amount of attention given to the flow-induced vibrations of heat exchangers by designers is usually related to the operational history of similar items of plant. Consequently, if a particular design procedure yields items of plant which behave in a satisfactory manner during their operational life, there is little incentive to improve or refine the design procedure. On the other hand, failures of heat exchangers clearly indicate deficiencies in the design procedures or in the data available to the designer. When such failures are attributable to flow-induced vibrations, the identification of the mechanisms involved is a prime importance. Ideally, basic research work provides the background understanding and the techniques necessary to be able to identify the important mechanisms. In practice, the investigation of a flow-induced vibration problem may identify the presence of mechanisms but may not be able to quantify their effects adequately. In these circumstances the need for additional work is established and the objectives of the research programme emerge. The purpose of this paper is to outline the background to the current research programme at C.E.R.L. on heat exchanger vibration.

Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

Science.gov (United States)

Chik, T. N. T.; Kamil, M. R. H.; Yusoff, N. A.

2018-04-01

Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations. The vibration level on the slab is acceptable within the limit that have been used by Gordon.

Effect of cooling on thixotropic position-sense error in human biceps muscle.

Science.gov (United States)

Sekihara, Chikara; Izumizaki, Masahiko; Yasuda, Tomohiro; Nakajima, Takayuki; Atsumi, Takashi; Homma, Ikuo

2007-06-01

Muscle temperature affects muscle thixotropy. However, it is unclear whether changes in muscle temperature affect thixotropic position-sense errors. We studied the effect of cooling on thixotropic position-sense errors induced by short-length muscle contraction (hold-short conditioning) in the biceps of 12 healthy men. After hold-short conditioning of the right biceps muscle in a cooled (5.0 degrees C) or control (36.5 degrees C) environment, subjects perceived greater extension of the conditioned forearm at 5.0 degrees C. The angle differences between the two forearms following hold-short conditioning of the right biceps muscle in normal or cooled conditions were significantly different (-3.335 +/- 1.680 degrees at 36.5 degrees C vs. -5.317 +/- 1.096 degrees at 5.0 degrees C; P=0.043). Induction of a tonic vibration reflex in the biceps muscle elicited involuntary forearm elevation, and the angular velocities of the elevation differed significantly between arms conditioned in normal and cooled environments (1.583 +/- 0.326 degrees /s at 36.5 degrees C vs. 3.100 +/- 0.555 degrees /s at 5.0 degrees C, P=0.0039). Thus, a cooled environment impairs a muscle's ability to provide positional information, potentially leading to poor muscle performance.

IAEA specialist meeting on flow induced vibrations in fast breeder reactors, Paris, France, 22-24 October 1986

International Nuclear Information System (INIS)

Perez, M.A.

1986-10-01

The Specialists' Meeting on ''Flow Induced Vibrations in FBRs for LMFBR Applications'' was held in Paris under the auspices of the French CEA on 21-24 October 1982. The meeting was sponsored by the IAEA on the recommendation of the 14th Meeting of the IWGFR and was attended by 31 participants from France, the Federal Republic of Germany, India, Italy, Japan, the United Kingdom, the Union of Soviet Socialist Republics, the United States of America and one international organization (IAEA). The meeting was presided over by Pr. R.J. Gibert of France. After the first session on review of national positions in the subject field (7 papers), the meeting was divided into five technical sections as follows: fluid-structures interaction, calculation methods (3 papers); tubes bundles vibration and weir (4 papers); instability (6 papers); induced vibrations in the pumps (2 papers). A separate abstract was prepared for each of these papers

FIVPET Flow-Induced Vibration Test Report (1) - Candidate Spacer Grid Type I (Optimized H Type)

Energy Technology Data Exchange (ETDEWEB)

Lee, Kang Hee; Kang, Heung Seok; Yoon, Kyung Ho; Song, Kee Nam; Kim, Jae Yong

2006-03-15

The flow-induced vibration (FIV) test using a 5x5 partial fuel assembly was performed to evaluate mechanical/structural performance of the candidate spacer grid type I (Optimized H shape). From the measured vibration response of the test bundle and the flow parameters, design features of the spacer strap can be analyzed in the point of vibration and hydraulic aspect, and also compared with other spacer strap in simple comparative manner. Furthermore, the FIV test will contributes to understand behaviors of nuclear fuel in operating reactor. The FIV test results will be used to verify the theoretical model of fuel rod and assembly vibration. The aim of this report is to present the results of the FIV test of partial fuel assembly and to introduce the detailed test methodology and analysis procedure. In chapter 2, the overall configuration of test bundle and instrumented tube is remarked and chapter 3 will introduce the test facility (FIVPET) and test section. Chapter 4 deals with overall test condition and procedure, measurement and data acquisition devices, instrumentation equipment and calibration, and error analysis. Finally, test result of vibration and pressure fluctuation is presented and discussed in chapter 5.

Counter flow induced draft cooling tower option for supercritical carbon dioxide Brayton cycle

Energy Technology Data Exchange (ETDEWEB)

Pidaparti, Sandeep R., E-mail: sandeep.pidaparti@gmail.com [Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, GA 30332 (United States); Moisseytsev, Anton; Sienicki, James J. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Ranjan, Devesh, E-mail: devesh.ranjan@me.gatech.edu [Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, GA 30332 (United States)

2015-12-15

Highlights: • A code was developed to investigate the various aspects of using cooling tower for S-CO{sub 2} Brayton cycles. • Cooling tower option to reject heat is quantitatively compared to the direct water cooling and dry air cooling options. • Optimum water conditions resulting in minimal plant capital cost per unit power consumption are calculated. - Abstract: A simplified qualitative analysis was performed to investigate the possibility of using counter flow induced draft cooling tower option to reject heat from the supercritical carbon dioxide Brayton cycle for advanced fast reactor (AFR)-100 and advanced burner reactor (ABR)-1000 plants. A code was developed to estimate the tower dimensions, power and water consumption, and to perform economic analysis. The code developed was verified against a vendor provided quotation and is used to understand the effect of ambient air and water conditions on the design of cooling tower. The calculations indicated that there exists optimum water conditions for given ambient air conditions which will result in minimum power consumption, thereby increasing the cycle efficiency. A cost-based optimization technique is used to estimate the optimum water conditions which will improve the overall plant economics. A comparison of different cooling options for the S-CO{sub 2} cycle indicated that the cooling tower option is a much more practical and economical option compared to the dry air cooling or direct water cooling options.

Large scale vibration tests on pile-group effects using blast-induced ground motion

International Nuclear Information System (INIS)

Katsuichirou Hijikata; Hideo Tanaka; Takayuki Hashimoto; Kazushige Fujiwara; Yuji Miyamoto; Osamu Kontani

2005-01-01

Extensive vibration tests have been performed on pile-supported structures at a large-scale mining site. Ground motions induced by large-scale blasting operations were used as excitation forces for vibration tests. The main objective of this research is to investigate the dynamic behavior of pile-supported structures, in particular, pile-group effects. Two test structures were constructed in an excavated 4 m deep pit. Their test-structures were exactly the same. One structure had 25 steel piles and the other had 4 piles. The test pit was backfilled with sand of appropriate grain size distributions to obtain good compaction, especially between the 25 piles. Accelerations were measured at the structures, in the test pit and in the adjacent free field, and pile strains were measured. Dynamic modal tests of the pile-supported structures and PS measurements of the test pit were performed before and after the vibration tests to detect changes in the natural frequencies of the soil-pile-structure systems and the soil stiffness. The vibration tests were performed six times with different levels of input motions. The maximum horizontal acceleration recorded at the adjacent ground surface varied from 57 cm/s 2 to 1,683 cm/s 2 according to the distances between the test site and the blast areas. (authors)

Molecular rotation-vibration dynamics of low-symmetric hydrate crystal in the terahertz region.

Science.gov (United States)

Fu, Xiaojian; Wu, Hongya; Xi, Xiaoqing; Zhou, Ji

2014-01-16

The rotational and vibrational dynamics of molecules in copper sulfate pentahydrate crystal are investigated with terahertz dielectric spectra. It is shown that the relaxation-like dielectric dispersion in the low frequency region is related to the reorientation of water molecules under the driving of terahertz electric field, whereas the resonant dispersion can be ascribed to lattice vibration. It is also found that, due to the hydrogen-bond effect, the vibrational mode at about 1.83 THz along [-111] direction softens with decreasing temperature, that is, the crystal expands in this direction when cooled. On the contrary, the mode hardens in the direction perpendicular to [-111] during the cooling process. This contributes to the further understanding of the molecular structure and bonding features of hydrate crystals.

Muscle-Cooling Intervention to Reduce Fatigue and Fatigue-Induced Tremor in Novice and Experienced Surgeons: A Preliminary Investigation.

Science.gov (United States)

Jensen, Lauren; Dancisak, Michael; Korndorffer, James

2016-10-01

A localized, intermittent muscle-cooling protocol was implemented to determine cooling garment efficacy in reducing upper extremity muscular fatigue and tremor in novice ( n  = 10) and experienced surgeons ( n  = 9). Subjects wore a muscle-cooling garment while performing multiple trials of a forearm exercise and paired suturing task to induce muscular fatigue and exercise-induced tremor. A reduction in tremor amplitude and an extension in time to fatigue were expected with muscle cooling as compared with control trials. Each subject completed an intervention session (5°C cooling condition) and a control session (32°C or thermal neutral condition). A paired samples t test indicated that tremor amplitude was significantly reduced ( t [8] = 1.89458; p  effect was not significant. Time to fatigue and suture time improved in both cohorts with muscle cooling, but the effect did not reach significance. Results from the pilot work suggest muscle cooling as an intervention for reduction of fatigue and tremor is very promising, warranting further investigation. Surgical specialties that require prolonged procedures might benefit more from this intervention.

Flow-induced vibration characteristics of the BWR/5-201 jet pump

International Nuclear Information System (INIS)

LaCroix, L.V.

1982-09-01

A General Electric boiling water reactor BWR/5-201 jet pump was tested for flow-induced vibration (FIV) characteristics in the Large Steam Water Test Facility at Moss Landing, CA, during the period June-July 1978. High level periodic FIV were observed at reactor operating conditions (1027 psia, 532 0 F and prototypical flow rates) for the specific single jet pump assembly tested. High level FIV of similar amplitude and character have been shown capable of damaging jet pump components and associated support hardware if allowed to continue unchecked. High level FIV were effectively suppressed in two special cases tested: (1) lateral load (>500 lb) at the mixer to diffuser slip joint; and (2) a labyrinth seal (5 small, circumferential grooves) on the mixer at the slip joint. Stability criteria for the particular jet pump tested were developed from test data. A cause-effect relationship between the dynamic pressure within the slip joint and the jet pump vibration was established

Numerical study on flow induced vibration characteristics of heat transfer tube

International Nuclear Information System (INIS)

Feng Zhipeng; Zang Fenggang; Zhang Yixiong

2014-01-01

The model presents a fully coupled approach with solving the fluid flow and the structure vibration simultaneously. The three-dimensional unsteady, viscous, incompressible Navier-Stokes equation and LES turbulence model were solved by the finite volume approach and the heat transfer structure was solved by finite element method combined with moving mesh control technique. The dynamic equilibrium equation was discretized according to the finite element theory and the mesh update was achieved by the dynamic mesh technology. Based on this model, flow induced vibration responses of the tube were thus investigated using response branch, phase angle, Lissajou diagram, trajectory, phase portrait and Poincare section mapping. Meanwhile, the limit cycle and bifurcation of lift coefficient and lateral displacement were analyzed. The results reveal that a quasi-upper branch is found in the fluid-structure interaction system, and there is no bifurcation of lift coefficient and lateral displacement occurred in three-dimensional flexible tube submitted to uniform turbulent flow. (authors)

Acute exposure to vibration is an apoptosis-inducing stimulus in the vocal fold epithelium.

Science.gov (United States)

Novaleski, Carolyn K; Kimball, Emily E; Mizuta, Masanobu; Rousseau, Bernard

2016-10-01

Clinical voice disorders pose significant communication-related challenges to patients. The purpose of this study was to quantify the rate of apoptosis and tumor necrosis factor-alpha (TNF-α) signaling in vocal fold epithelial cells in response to increasing time-doses and cycle-doses of vibration. 20 New Zealand white breeder rabbits were randomized to three groups of time-doses of vibration exposure (30, 60, 120min) or a control group (120min of vocal fold adduction and abduction). Estimated cycle-doses of vocal fold vibration were extrapolated based on mean fundamental frequency. Laryngeal tissue specimens were evaluated for apoptosis and gene transcript and protein levels of TNF-α. Results revealed that terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was significantly higher after 120min of vibration compared to the control. Transmission electron microscopy (TEM) revealed no significant effect of time-dose on the mean area of epithelial cell nuclei. Extrapolated cycle-doses of vibration exposure were closely related to experimental time-dose conditions, although no significant correlations were observed with TUNEL staining or mean area of epithelial cell nuclei. TUNEL staining was positively correlated with TNF-α protein expression. Our findings suggest that apoptosis can be induced in the vocal fold epithelium after 120min of modal intensity phonation. In contrast, shorter durations of vibration exposure do not result in apoptosis signaling. However, morphological features of apoptosis are not observed using TEM. Future studies are necessary to examine the contribution of abnormal apoptosis to vocal fold diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flow induced vibrations of piping system (Vibration sources - Mechanical response of the pipes)

International Nuclear Information System (INIS)

Gibert, R.J.; Axisa, F.; Villard, B.

1978-01-01

In order to design the supports of piping system, an estimation of the vibration induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary. To evaluate the power spectra of all the main sources generated by the flow. These sources are located at the singular points of the circuit (enlargements, bends, valves, etc. ...). To calculate the modal parameters of fluid containing pipes. This paper presents: a methodical study of the most current singularities. Inter-correlation spectra of local pressure fluctuation downstream from the singularity and correlation spectra of associated acoustical sources have been measured. A theory of noise generation by unsteady flow in internal acoustics has been developed. All these results are very useful for evaluating the source characteristics in most practical pipes. A comparison between the calculation and the results of an experimental test has shown a good agreement

Vibrationally induced nuclear quadrupole coupling in the v3 = 1 state of 189OsO4

International Nuclear Information System (INIS)

Scappini, F.; Kreiner, W.A.; Frye, J.M.; Oka, T.

1987-01-01

Electric nuclear quadrupole hyperfine structure arising from a quadrupolar nucleus at the center of tetrahedral molecules, such as 189 OsO 4 , is symmetry forbidden. However, through vibration--rotation distortion a small nuclear quadrupole coupling is induced. The hyperfine structure due to the vibrationally induced eqQ has been measured for a number of P- and R-branch transitions in the ν 3 fundamental of 189 OsO 4 , by using inverse Lamb dip spectroscopy. Microwave modulation sidebands of CO 2 laser lines have been used as the tunable infrared radiation. From the analysis of the observed hyperfine structure patterns, the values of the scalar and tensor coupling constants have been determined to be chi/sup V//sub s/ = -4.103 +- 0.048 MHz and chi/sup V//sub t/ = -3.090 +- 0.059 MHz

Study and analysis for the flow-induced vibration of the core barrel of a PWR

International Nuclear Information System (INIS)

Yao Weida; Shi Guolin; Jiang Nanyan

1989-01-01

The resemblance criteria are derived and a test model is designed by applying the flow-soild coupling theory. After having completed the model analysis of the pressurized water reactor (PWR) core barrel in an 1:10 model, the dynamic characteristics are obtained. In an 1:5 reactor model with a hydraulic closed loop, the hydraulic vibration tests of the core barrel are performed, and the relations between the flow rate and the flow-induced pulse pressure on core barrel, acceleration and strain signals have been measured. The corresponding responses and a group of computational equations for hydraulic vibration are derived from these two experiments. The computational hydraulic vibration responses for core barrel in Qinshan Nuclear Power Plant are in good agreement with the test results, and it shows that the core barrel is safe within its lifetime of 30 years

The photodissociation and reaction dynamics of vibrationally excited molecules

Energy Technology Data Exchange (ETDEWEB)

Crim, F.F. [Univ. of Wisconsin, Madison (United States)

1993-12-01

This research determines the nature of highly vibrationally excited molecules, their unimolecular reactions, and their photodissociation dynamics. The goal is to characterize vibrationally excited molecules and to exploit that understanding to discover and control their chemical pathways. Most recently the author has used a combination of vibrational overtone excitation and laser induced fluorescence both to characterize vibrationally excited molecules and to study their photodissociation dynamics. The author has also begun laser induced grating spectroscopy experiments designed to obtain the electronic absorption spectra of highly vibrationally excited molecules.

Analytical Model of Underground Train Induced Vibrations on Nearby Building Structures in Cameroon: Assessment and Prediction

Directory of Open Access Journals (Sweden)

Lezin Seba MINSILI

2013-11-01

Full Text Available The purpose of this research paper was to assess and predict the effect of vibrations induced by an underground railway on nearby-existing buildings prior to the construction of projected new railway lines of the National Railway Master Plan of Cameroon and after upgrading of the railway conceded to CAMRAIL linking the two most densely populated cities of Cameroon: Douala and Yaoundé. With the source-transmitter-receiver mathematical model as the train-soil-structure interaction model, taking into account sub-model parameters such as type of the train-railway system, typical geotechnical conditions of the ground and the sensitivity of the nearby buildings, the analysis is carried out over the entire system using the dynamic finite element method in the time domain. This subdivision of the model is a powerful tool that allows to consider different alternatives of sub-models with different characteristics, and thus to determine any critical excessive vibration impact. Based on semi-empirical analytical results obtained from presented models, the present work assesses and predicts characteristics of traffic-induced vibrations as a function of time duration, intensity and vehicle speed, as well as their influence on buildings at different levels.

Vibration of hydraulic machinery

CERN Document Server

Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

2013-01-01

Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

Flow induced vibration studies for LMFBR in Japan: Past and recent studies of FIV for JOYO and MONJU

Energy Technology Data Exchange (ETDEWEB)

Sato, K [Sodium Engineering Division, O-arai Engineering Centre, Power Reactor and Nuclear Fuel, Development Corporation, Narita-cho, O-arai Machi, Ibaraki-ken (Japan)

1977-12-01

This paper presents the past and recent studies of flow induced vibration of the reactor components for the experimental fast breeder reactor JOYO and the prototype fast breeder reactor MONJU, in which many suggestive results for the higher flow velocity systems in a future reactor are contained. The fuel subassembly is the most important from the view point of the vibration. Thus, the studies were carried out with a mock-up subassembly for JOYO. In this experiment, statistical analysis results of the vibration characteristics of single core subassembly and the effects of external forced vibration, flow disturbance and fuel pin bundle vibration were reported. The further more detailed investigations are now being performed for MONJU. In addition to the above studies, the vibration failure of a sodium valve is reported. The valve is a 8-inch stop valve in SODIUM FLOW AND HEAT TRANSFER TEST LOOP at O-arai Engineering Center. The failure occurred in 1969 during the performance test of the mechanical pump, and this resulted in a small sodium leak. The cause of the failure was found to be the vibration fatigue of the metal bellows. (author)

Factors influencing the effectiveness of scalp cooling in the prevention of chemotherapy-induced alopecia.

Science.gov (United States)

Komen, Manon M C; Smorenburg, Carolien H; van den Hurk, Corina J G; Nortier, Johan W R

2013-01-01

The success of scalp cooling in preventing or reducing chemotherapy-induced alopecia (CIA) is highly variable between patients and chemotherapy regimens. The outcome of hair preservation is often unpredictable and depends on various factors. Methods. We performed a structured search of literature published from 1970 to February 2012 for articles that reported on factors influencing the effectiveness of scalp cooling to prevent CIA in patients with cancer. Results. The literature search identified 192 reports, of which 32 studies were considered relevant. Randomized studies on scalp cooling are scarce and there is little information on the determinants of the result. The effectiveness of scalp cooling for hair preservation depends on dose and type of chemotherapy, with less favorable results at higher doses. Temperature seems to be an important determinant. Various studies suggest that a subcutaneous scalp temperature less than 22 °C is required for hair preservation. Conclusions. The effectiveness of scalp cooling for hair preservation varies by chemotherapy type and dose, and probably by the degree and duration of cooling.

Isotope separation using vibrationally excited molecules

International Nuclear Information System (INIS)

Woodroffe, J.A.; Keck, J.C.

1979-01-01

Vibrational excitation of molecules having components of a selected isotope type is used to produce a conversion from vibrational to translational excitation of the molecules by collision with the molecules of a heavy carrier gas. The resulting difference in translaton between the molecules of the selected isotope type and all other molecules of the same compound permits their separate collection. When applied to uranium enrichment, a subsonic cryogenic flow of molecules of uranium hexafluoride in combination with an argon carrier gas is directed through a cooled chamber that is illuminated by laser radiaton tuned to vibrationally excite the uranium hexafluoride molecules of a specific uranium isotope. The excited molecules collide with carrier gas molecules, causing a conversion of the excitation energy into a translation of the excited molecule, which results in a higher thermal energy or diffusivity than that of the other uranium hexafluoride molecules. The flowing molecules including the excited molecules directly enter a set of cryogenically cooled channels. The higher thermal velocity of the excited molecules increases the probability of their striking a collector surface. The molecules which strike this surface immediately condense. After a predetermined thickness of molecules is collected on the surface, the flow of uranium hexafluoride is interrupted and the chamber heated to the point of vaporization of the collected hexafluoride, permitting its removal. (LL)

Vibrational dynamics of ice in reverse micelles

NARCIS (Netherlands)

Dokter, A.M.; Petersen, C.; Woutersen, S.; Bakker, H.J.

2008-01-01

he ultrafast vibrational dynamics of HDO:D2O ice at 180 K in anionic reverse micelles is studied by midinfrared femtosecond pump-probe spectroscopy. Solutions containing reverse micelles are cooled to low temperatures by a fast-freezing procedure. The heating dynamics of the micellar solutions is

Using vibrational molecular spectroscopy to reveal association of steam-flaking induced carbohydrates molecular structural changes with grain fractionation, biodigestion and biodegradation

Science.gov (United States)

Xu, Ningning; Liu, Jianxin; Yu, Peiqiang

2018-04-01

Advanced vibrational molecular spectroscopy has been developed as a rapid and non-destructive tool to reveal intrinsic molecular structure conformation of biological tissues. However, this technique has not been used to systematically study flaking induced structure changes at a molecular level. The objective of this study was to use vibrational molecular spectroscopy to reveal association between steam flaking induced CHO molecular structural changes in relation to grain CHO fractionation, predicted CHO biodegradation and biodigestion in ruminant system. The Attenuate Total Reflectance Fourier-transform Vibrational Molecular Spectroscopy (ATR-Ft/VMS) at SRP Key Lab of Molecular Structure and Molecular Nutrition, Ministry of Agriculture Strategic Research Chair Program (SRP, University of Saskatchewan) was applied in this study. The fractionation, predicted biodegradation and biodigestion were evaluated using the Cornell Net Carbohydrate Protein System. The results show that: (1) The steam flaking induced significant changes in CHO subfractions, CHO biodegradation and biodigestion in ruminant system. There were significant differences between non-processed (raw) and steam flaked grain corn (P R2 = 0.87, RSD = 0.74, P R2 = 0.87, RSD = 0.24, P < .01). In summary, the processing induced molecular CHO structure changes in grain corn could be revealed by the ATR-Ft/VMS vibrational molecular spectroscopy. These molecular structure changes in grain were potentially associated with CHO biodegradation and biodigestion.

Anharmonicity of lattice vibrations induced by charged nickel additions in A sup 2 B sup 6 semiconductors

CERN Document Server

Sokolov, V I; Shirokov, E A; Kislov, A N

2002-01-01

Paper presents the results of investigations into lattice vibrations induced by nickel impurities charged negatively as to the lattice in ZnSe:Ni, ZnO:Ni, ZnS:Ni, CdS:Ni semiconductors. To investigate into vibrations one applies a sensitive technique of field exciton-oscillation spectroscopy. One observes experimentally oscillating reiterations of the impurity exciton head line including the intensive peaks of combined repetitions up to the 8-th order. The experimental results are discussed on the basis of the model estimations of oscillations of a lattice with a charged impurity centre, as well as, on the ground of calculations for oscillations of monoatomic chain with high anharmonicity. Charged impurity centres are shown to induce new oscillations of lattice - impurity anharmonic modes

Multipole induced splitting of metal-cage vibrations in crystalline endohedral D2d-M2@C84 dimetallofullerenes.

Science.gov (United States)

Krause, M; Popov, V N; Inakuma, M; Tagmatarchis, N; Shinohara, H; Georgi, P; Dunsch, L; Kuzmany, H

2004-01-22

Metal-carbon cage vibrations of crystalline endohedral D2d-M2@C84 (M=Sc,Y,Dy) dimetallofullerenes were analyzed by temperature dependent Raman scattering and a dynamical force field model. Three groups of metal-carbon cage modes were found at energies of 35-200 cm(-1) and assigned to metal-cage stretching and deformation vibrations. They exhibit a textbook example for the splitting of molecular vibrations in a crystal field. Induced dipole-dipole and quadrupole-quadrupole interactions account quantitatively for the observed mode splitting. Based on the metal-cage vibrational structure it is demonstrated that D2d-Y2@C84 dimetallofullerene retains a monoclinic crystal structure up to 550 K and undergoes a transition from a disordered to an ordered orientational state at a temperature of approximately 150 K.

Effect of structural design on traffic-induced building vibrations

DEFF Research Database (Denmark)

Persson, Peter; Andersen, Lars Vabbersgaard; Persson, Kent

2017-01-01

Population growth and urbanization results in densified cities, where new buildings are being built closer to existing vibration sources such as road-, tram- and rail traffic. In addition, new transportation systems are constructed closer to existing buildings. Potential disturbing vibrations...... are one issue to consider in planning urban environment and densification of cities. Vibrations can be disturbing for humans but also for sensitive equipment in, for example, hospitals. In determining the risk for disturbing vibrations, the distance between the source and the receiver, the ground...... properties, and type and size of the building are governing factors. In the paper, a study is presented aiming at investigating the influence of various parameters of the building's structural design on vibration levels in the structure caused by ground surface loads, e.g. traffic. Parameters studied...

Experimental study of hydrodynamically induced vibrational processes in VVER-440 fuel assemblies

International Nuclear Information System (INIS)

Solonin, V.I.; Perevezentsev, V.V.; Rekshnya, N.F.; Krapivtsev, V.G.

2000-01-01

Investigations are described of hydrodynamically induced vibrations in a single fuel assembly of a VVER-440 reactor, performed on a full-scale model installed in a closed loop filled with distilled water; the model fuel elements contained simulators of fuel pellets. Data on hydrodynamic loads were obtained by measuring pressure oscillations along the height of the fuel assembly case. Results of the measurements are presented in graphs and are discussed in some detail. (A.K.)

Analysis of flow-induced vibration of heat exchanger and steam generator tube bundles using the AECL computer code PIPEAU-2

International Nuclear Information System (INIS)

Gorman, D.J.

1983-12-01

PIPEAU-2 is a computer code developed at the Chalk River Nuclear Laboratories for the flow-induced vibration analysis of heat exchanger and steam generator tube bundles. It can perform this analysis for straight and 'U' tubes. All the theoretical work underlying the code is analytical rather than numerical in nature. Highly accurate evaluation of the free vibration frequencies and mode shapes is therefore obtained. Using the latest experimentally determined parameters available, the free vibration analysis is followed by a forced vibration analysis. Tube response due to fluid turbulence and vortex shedding is determined, as well as critical fluid velocity associated with fluid-elastic instability

Piezoelectric energy harvesting from flow-induced vibration

International Nuclear Information System (INIS)

Wang, D-A; Ko, H-H

2010-01-01

A new piezoelectric energy harvester for harnessing energy from flow-induced vibration is developed. It converts flow energy into electrical energy by piezoelectric conversion with oscillation of a piezoelectric film. A finite element model is developed in order to estimate the generated voltage of the piezoelectric laminate subjected to a distributed load. Prototypes of the energy harvester are fabricated and tested. Experimental results show that an open circuit output voltage of 2.2 V pp and an instantaneous output power of 0.2 µW are generated when the excitation pressure oscillates with an amplitude of 1.196 kPa and a frequency of about 26 Hz. The solution of the generated voltage based on the finite element model agrees well with the experiments. Based on the finite element model, the effects of the piezoelectric film dimensions, the fluid pressure applied to the harvester and types of piezoelectric layer on the output voltage of the harvester can be investigated.

The Skull Vibration-Induced Nystagmus Test of Vestibular Function—A Review

Science.gov (United States)

Dumas, Georges; Curthoys, Ian S.; Lion, Alexis; Perrin, Philippe; Schmerber, Sébastien

2017-01-01

A 100-Hz bone-conducted vibration applied to either mastoid induces instantaneously a predominantly horizontal nystagmus, with quick phases beating away from the affected side in patients with a unilateral vestibular loss (UVL). The same stimulus in healthy asymptomatic subjects has little or no effect. This is skull vibration-induced nystagmus (SVIN), and it is a useful, simple, non-invasive, robust indicator of asymmetry of vestibular function and the side of the vestibular loss. The nystagmus is precisely stimulus-locked: it starts with stimulation onset and stops at stimulation offset, with no post-stimulation reversal. It is sustained during long stimulus durations; it is reproducible; it beats in the same direction irrespective of which mastoid is stimulated; it shows little or no habituation; and it is permanent—even well-compensated UVL patients show SVIN. A SVIN is observed under Frenzel goggles or videonystagmoscopy and recorded under videonystagmography in absence of visual-fixation and strong sedative drugs. Stimulus frequency, location, and intensity modify the results, and a large variability in skull morphology between people can modify the stimulus. SVIN to 100 Hz mastoid stimulation is a robust response. We describe the optimum method of stimulation on the basis of the literature data and testing more than 18,500 patients. Recent neural evidence clarifies which vestibular receptors are stimulated, how they cause the nystagmus, and why the same vibration in patients with semicircular canal dehiscence (SCD) causes a nystagmus beating toward the affected ear. This review focuses not only on the optimal parameters of the stimulus and response of UVL and SCD patients but also shows how other vestibular dysfunctions affect SVIN. We conclude that the presence of SVIN is a useful indicator of the asymmetry of vestibular function between the two ears, but in order to identify which is the affected ear, other information and careful clinical judgment are

Spectroscopy and reactions of vibrationally excited transient molecules

Energy Technology Data Exchange (ETDEWEB)

Dai, H.L. [Univ. of Pennsylvania, Philadelphia (United States)

1993-12-01

Spectroscopy, energy transfer and reactions of vibrationally excited transient molecules are studied through a combination of laser-based excitation techniques and efficient detection of emission from the energized molecules with frequency and time resolution. Specifically, a Time-resolved Fourier Transform Emission Spectroscopy technique has been developed for detecting dispersed laser-induced fluorescence in the IR, visible and UV regions. The structure and spectroscopy of the excited vibrational levels in the electronic ground state, as well as energy relaxation and reactions induced by specific vibronic excitations of a transient molecule can be characterized from time-resolved dispersed fluorescence in the visible and UV region. IR emissions from highly vibrational excited levels, on the other hand, reveal the pathways and rates of collision induced vibrational energy transfer.

Wind-induced Vibrations in the European Court Towers

DEFF Research Database (Denmark)

Hansen, Jannick B.; Brincker, Rune; Andersen, Ken G.

2012-01-01

Issues regarding occupancy comfort in vibration-sensitive structures are the motivation of this study concerning windinduced vibrations in the European Court Towers in Luxembourg. In one of the two identical towers tuned liquid dampers (TLD) have been installed. Recent studies investigate the cha...

Enhancement of Energy Harvesting Performance by a Coupled Bluff Splitter Body and PVEH Plate through Vortex Induced Vibration near Resonance

Directory of Open Access Journals (Sweden)

Wei Ken Chin

2017-09-01

Full Text Available Inspired by vortex induced vibration energy harvesting development as a new source of renewable energy, a T-shaped design vibration energy harvester is introduced with the aim of enhancing its performance through vortex induced vibration at near resonance conditions. The T-shaped structural model designed consists of a fixed boundary aluminum bluff splitter body coupled with a cantilever piezoelectric vibration energy harvesters (PVEH plate model which is a piezoelectric bimorph plate made of a brass plate sandwiched between 2 lead zirconate titanate (PZT plates. A 3-dimensional Fluid-Structure Interaction simulation analysis is carried out with Reynolds Stress Turbulence Model under wind speed of 7, 10, 12, 14, 16, 18, 19, 20, 22.5, and 25 m/s. The results showed that with 19 m/s wind speed, the model generates 75.758 Hz of vortex frequency near to the structural model’s natural frequency of 76.9 Hz. Resonance lock-in therefore occurred, generating a maximum displacement amplitude of 2.09 mm or a 49.76% increment relatively in vibrational amplitude. Under the effect of resonance at the PVEH plate’s fundamental natural frequency, it is able to generate the largest normalized power of 13.44 mW/cm3g2.

PWR control rods wear by vibrations induced by coolant fluid

International Nuclear Information System (INIS)

Reynier, R.

1997-01-01

Flow induced vibrations in pressurised water reactors generate the wear of control rods against their guidance systems. Alternate sliding (at 320 deg. C in water) and impact-sliding tests (at room temperature in air) were carried out on 304 L austenitic stainless steel control rods' claddings. Microstructural analysis were made on the wear scars of the tube specimen using Scanning ELectron Microscopy, microhardness measurements and X-ray diffractometry. The alternate sliding leads to an important mass loss, a strong plastic deformation due to the strain hardening of the surface layers and generates strong compressive residual stresses. These results are specific to a severe wear case. Therefore, the impact-sliding mode induces martensitic phase, a cracked oxide layer and a compressive residual stresses weaker than those created in the alternate sliding case. This type of motion leads to a milder wear of the control rods

A study on the annular leakage-flow-induced vibrations. 1st report. Stability for translational and rotational single-degree-of-freedom systems

International Nuclear Information System (INIS)

Li, Dong-Wei; Kaneko, Shigehiko; Hayama, Shinji

1999-01-01

This study reports the stability of annular leakage-flow-induced vibrations. The pressure distribution of fluid between a fixed outer cylinder and a vibrating inner cylinder was obtained in the case of a translationally and rotationally coupled motion of the inner cylinder. The unsteady fluid force acting on the inner cylinder in the case of translational and rotational single-degree-of-freedom vibrations was then expressed in terms proportional to the acceleration, velocity, and displacement. Then the critical flow rate (at which stability was lost) was determined for an annular leakage-flow-induced vibration. Finally, the stability was investigated theoretically. It is known that instability will occur in the case of a divergent passage, but the critical flow rate depends on the passage increment in a limited range: the eccentricity of the passage and the pressure loss factor at the inlet of the passage lower the stability. (author)

Theoretical study on flow-induced vibration of a cylindrical weir due to fluid discharge

International Nuclear Information System (INIS)

Fujita, Katsuhisa; Ito, Tomohiro; Hirota, Kazuo; Kodama, Tetsuhiko

1994-01-01

In a FBR, the inside of the reactor vessel is cooled by liquid sodium. Liquid sodium is supplied to the upper plenum from its bottom and discharges over the top of the cylindrical weir down to the lower plenum. The weir is so thin in order to decrease the thermal stress on it that the fluid--structure interaction becomes predominant. A fluidelastic vibration of the weir due to fluid discharge was discovered in a French FBR. In this study, a theoretical model was developed on the ''fluid--elastic mode'' instability of a cylindrical weir due to fluid discharge from the upper plenum to the lower plenum. In the analysis, the fluctuation of both the discharge flow rate over a weir due to the vibration of the cylindrical shell and the pressure in the lower plenum due to fluid discharge were formulated. Instability criteria was derived from the added damping ratio due to fluid discharge using modal analysis. The natural modes and modal mass of the weir were obtained by the analysis using the FEM code taking the fluid - structure interaction into consideration. The theoretical instability range in terms of the fall height and the flow rate is compared with the experimental results. The theoretical values showed a good agreement with the experimental ones

Flow induced vibration and stability analysis of multi wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Yun, Kyung Jae [Agency for Defense Development, Daejeon (Korea, Republic of); Choi, Jong Woon [Korean Intellectual Property Office, Daejeon (Korea, Republic of); Kim, Sung Kyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Song, Oh Seop [Chungnam National Univ., Daejeon (Korea, Republic of)

2012-12-15

The free vibration and flow induced flutter instability of cantilever multi wall carbon nanotubes conveying fluid are investigated and the nanotubes are modeled as thin-walled beams. The non-classical effects of the transverse shear, rotary inertia, warping inhibition, and van der Waals forces between two walls are incorporated into the structural model. The governing equations and associated boundary conditions are derived using Hamilton's principle. A numerical analysis is carried out by using the extended Galerkin method, which enables us to obtain more accurate solutions compared to the conventional Galerkin method. Cantilevered carbon nanotubes are damped with decaying amplitude for a flow velocity below a certain critical value. However, beyond this critical flow velocity, flutter instability may occur. The variations in the critical flow velocity with respect to both the radius ratio and length of the carbon nanotubes are investigated and pertinent conclusions are outlined. The differences in the vibration and instability characteristics between the Timoshenko beam theory and Euler beam theory are revealed. A comparative analysis of the natural frequencies and flutter characteristics of MWCNTs and SWCNTs is also performed.

The Impact of Traffic-Induced Bridge Vibration on Rapid Repairing High-Performance Concrete for Bridge Deck Pavement Repairs

Directory of Open Access Journals (Sweden)

Wei Wang

2014-01-01

Full Text Available Based on forced vibration tests for high-performance concrete (HPC, the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

BVI induced vibration and noise alleviation by active and passive approaches

Science.gov (United States)

Liu, Li

This dissertation describes the development of a comprehensive aeroelastic/aeroacoustic simulation capability for the modeling of vibration and noise in rotorcraft induced by blade-vortex interaction (BVI). Subsequently this capability is applied to study vibration and noise reduction, using active and passive control approaches. The active approach employed is the actively controlled partial span trailing edge flaps (ACF), implemented in single and dual, servo and plain flap configurations. The passive approach is based on varying the sweep and anhedral on the tip of the rotor. Two different modern helicopters are chosen as the baseline for the implementation of ACF approach, one resembling a four-bladed MBB BO-105 hingeless rotor and the other similar to a five-bladed MD-900 bearingless rotor. The structural model is based on a finite element approach capable of simulating composite helicopter blades with swept tips, and representing multiple load paths at the blade root which is a characteristic of bearingless rotors. An unsteady compressible aerodynamic model based on a rational function approximation (RFA) approach is combined with a free wake analysis which has been enhanced by improving the wake analysis resolution and modeling a dual vortex structure. These enhancements are important for capturing BVI effects. A method for predicting compressible unsteady blade surface pressure distribution on rotor blades has been developed, which is required by the acoustic analysis. A modified version of helicopter noise code WOPWOP with provisions for blade flexibility has been combined with the aeroelastic analysis to predict the BVI noise. Several variants of the higher harmonic control (HHC) algorithm have been applied for the active noise control, as well as the simultaneous vibration and noise control. Active control of BVI noise is accomplished using feedback from an onboard microphone. The simulation has been extensively validated against experimental data and

Laboratory measurements of vortex- and wake-induced vibrations of a tandem arrangement of two flexible risers

Science.gov (United States)

Liu, Huai-zeng; Wang, Fei; Jiang, Guo-sheng; Guo, Hai-yan; Li, Xiao-min

2016-03-01

The dynamic response of two flexible model risers in tandem arrangement immersed in a stepped current was analyzed. The risers, with an external diameter of 20 mm and a total length of 6200 mm, had an aspect ratio of 310. They were hinged to the support structure at the center-to-center distances away 3-12 times the external diameter. The top 1200 mm was exposed to a uniform current at a speed which was up to 0.9 m/s (the Reynolds number was 18000) and the rest in still water. The dynamic responses, which were obtained through the Fiber Bragg Grating strain gauges mounted on the surface, were analyzed by studying the cross-flow amplitudes and modal weights. The cross-flow vibration were observed up to the third mode, and the modal transformation from the second mode to the third mode was clearly observed. The experiment confirmed that the typical vortex-induced vibration (VIV) had occurred on the up-stream riser. But for the down-stream riser, the main excitation mechanism was wake-induced vibration (WIV). The modal transformation of WIV was more complex than that of VIV, which might be helpful for other researchers to study the interference effect.

Understanding and controlling wind-induced vibrations of bridge cables: Results from the Femern Crossing research project

DEFF Research Database (Denmark)

Georgakis, Christos T.; Jakobsen, J. B.; Koss, Holger

of the project has been the establishment of novel vibration mitigation schemes that could be readily, economically, and effectively implemented on a cable-supported bridge that might form part of the fixed link. In support of the proposed research, Femern A/S commissioned a new climatic wind tunnel, designed......Following the successful completion of the Storebælt and Øresund Crossings, the Danish Ministry of Transport appointed Femern A/S to be in charge of preparation, investigations and planning in relation to the establishment of a fixed link across the Fehmarnbelt. To further investigate the causes...... behind the cable vibrations that were observed on the cable-supported bridges forming part of the aforementioned crossings, Femern A/S commissioned a 5-year international collaborative research project, entitled “Understanding and controlling wind-induced vibrations of bridge cables”. The ultimate goal...

Smooth polishing of femtosecond laser induced craters on cemented carbide by ultrasonic vibration method

Science.gov (United States)

Wang, H. P.; Guan, Y. C.; Zheng, H. Y.

2017-12-01

Rough surface features induced by laser irradiation have been a challenging for the fabrication of micro/nano scale features. In this work, we propose hybrid ultrasonic vibration polishing method to improve surface quality of microcraters produced by femtosecond laser irradiation on cemented carbide. The laser caused rough surfaces are significantly smoothened after ultrasonic vibration polishing due to the strong collision effect of diamond particles on the surfaces. 3D morphology, SEM and AFM analysis has been conducted to characterize surface morphology and topography. Results indicate that the minimal surface roughness of Ra 7.60 nm has been achieved on the polished surfaces. The fabrication of microcraters with smooth surfaces is applicable to molding process for mass production of micro-optical components.

Design specifications to ensure flow-induced vibration and fretting-wear performance in CANDU steam generators and heat exchangers

International Nuclear Information System (INIS)

Janzen, V.P.; Han, Y.; Pettigrew, M.J.

2009-01-01

Preventing flow-induced vibration and fretting-wear problems in steam generators and heat exchangers requires design specifications that bring together specific guidelines, analysis methods, requirements and appropriate performance criteria. This paper outlines the steps required to generate and support such design specifications for CANDU nuclear steam generators and heat exchangers, and relates them to typical steam-generator design features and computer modeling capabilities. It also describes current issues that are driving changes to flow-induced vibration and fretting-wear specifications that can be applied to the design process for component refurbishment, replacement or new designs. These issues include recent experimental or field evidence for new excitation mechanisms, e.g., the possibility of in-plane fluidelastic instability of U-tubes, the demand for longer reactor and component lifetimes, the need for better predictions of dynamic properties and vibration response, e.g., two-phase random-turbulence excitation, and requirements to consider system 'excursions' or abnormal scenarios, e.g., a main steam line break in the case of steam generators. The paper describes steps being taken to resolve these issues. (author)

Influence of light-induced conical intersection on the photodissociation dynamics of D2(+) starting from individual vibrational levels.

Science.gov (United States)

Halász, Gábor J; Csehi, András; Vibók, Ágnes; Cederbaum, Lorenz S

2014-12-26

Previous works have shown that dressing of diatomic molecules by standing or by running laser waves gives rise to the appearance of so-called light-induced conical intersections (LICIs). Because of the strong nonadiabatic couplings, the existence of such LICIs may significantly change the dynamical properties of a molecular system. In our former paper (J. Phys. Chem. A 2013, 117, 8528), the photodissociation dynamics of the D(2)(+) molecule were studied in the LICI framework starting the initial vibrational nuclear wave packet from the superposition of all the vibrational states initially produced by ionizing D(2). The present work complements our previous investigation by letting the initial nuclear wave packets start from different individual vibrational levels of D(2)(+), in particular, above the energy of the LICI. The kinetic energy release spectra, the total dissociation probabilities, and the angular distributions of the photofragments are calculated and discussed. An interesting phenomenon has been found in the spectra of the photofragments. Applying the light-induced adiabatic picture supported by LICI, explanations are given for the unexpected structure of the spectra.

Analysis of the Suppression Device as Vortex Induced Vibration (VIV Reducer on Free Span using Finite Element Method

Directory of Open Access Journals (Sweden)

Dwi Priyanta

2016-12-01

Full Text Available Subsea pipeline is a transportation infrastructure of oil and gas as an alternative for ship tanker. The uneven topography surface of the sea floor resulting the pipe undergoes free span. The free span is a condition endured by the pipe where the pipe position has  distance or gap with the seabed supported by two pivot. The free span is at risk of experiencing a vibration caused by the presence of dynamic load that is current and the wave. The vibration that occurs is the impact of the presence of the phenomenon of Vortex Induced Vibration (VIV. The Phenomenon Of VIV occur on a cylindrical component caused by ocean currents, causing the occurrence of vibration by the movement of fluid on the pipe so that it raises the vortex at the rear of the direction of oncoming flow. One way to dampen or reduce the impact of VIV is by adding suppresion device. VIV suppression device is a tool that is installed on the pipeline on offshore piping installationcthat serves to dampen or reduce the impact of VIV. One of the simulations used to know the characteristics of a fluid is to use (CFD Computational Fluid Dynamic. With the addition of suppression device can add the rest of the operating time on a free span of affected VIV, on the condition of free span critical exposed VIV (Vortex Induced Vibration value has a life time on plain pipe 44.21 years, on pipe with 53.09 years and Fairing on the pipe with the Helical strike 52.95 year.

Floor Vibrations - as Induced and Reduced by Humans

DEFF Research Database (Denmark)

Pedersen, Lars

. As for dynamic loads focus is placed on heel impact excitation and actions of jumping people causing floor vibrations. As for interaction between stationary humans and the vibrating floor focus is on modelling humans as oscillating spring-mass-damper systems attached to the floor rather than as simple added mass...

An advanced tube wear and fatigue workstation to predict flow induced vibrations of steam generator tubes

International Nuclear Information System (INIS)

Gay, N.; Baratte, C.; Flesch, B.

1997-01-01

Flow induced tube vibration damage is a major concern for designers and operators of nuclear power plant steam generators (SG). The operating flow-induced vibrational behaviour has to be estimated accurately to allow a precise evaluation of the new safety margins in order to optimize the maintenance policy. For this purpose, an industrial 'Tube Wear and Fatigue Workstation', called 'GEVIBUS Workstation' and based on an advanced methodology for predictive analysis of flow-induced vibration of tube bundles subject to cross-flow has been developed at Electricite de France. The GEVIBUS Workstation is an interactive processor linking modules as: thermalhydraulic computation, parametric finite element builder, interface between finite element model, thermalhydraulic code and vibratory response computations, refining modelling of fluid-elastic and random forces, linear and non-linear dynamic response and the coupled fluid-structure system, evaluation of tube damage due to fatigue and wear, graphical outputs. Two practical applications are also presented in the paper; the first simulation refers to an experimental set-up consisting of a straight tube bundle subject to water cross-flow, while the second one deals with an industrial configuration which has been observed in some operating steam generators i.e., top tube support plate degradation. In the first case the GEVIBUS predictions in terms of tube displacement time histories and phase planes have been found in very good agreement with experiment. In the second application the GEVIBUS computation showed that a tube with localized degradation is much more stable than a tube located in an extended degradation zone. Important conclusions are also drawn concerning maintenance. (author)

Experimental validation of the design method to prevent flow-induced vibration in high Reynolds-number

International Nuclear Information System (INIS)

Sakai, Takaaki; Yamaguchi, Akira; Morisita, Masaki; Iwata, Koji

1998-08-01

The incident of sodium leakage from a main pipe of the secondary heat transport system of Monju fast breeder reactor was caused by the failure of a thermometer well. 'Flow-induced vibration design guide for thermometer wells' (express as 'design guide') was proposed by PNC Working Group to prevent the same cause of the sodium leak incident in future. On this report, applicability of the 'design guide' was estimated to plant conditions in high Reynolds-number(approximately 3x10 5 ∼ 3x10 6 ) involving the supercritical region, by measured data on a vortex synchronized vibration and a turbulence induced vibration. Experiments were performed for cylindrical and taper shaped types of test pieces. As results, reduced velocity (Vr) at onsets of the inline synchronized vibration were evaluated to be grater than 1.0 in the range of experimental conditions. Fluctuating drag and lift coefficients, which were evaluated from power spectrum of turbulence for Vr < 1.0 condition, were 0.01 ∼ 0.05 for drag direction and 0.04 ∼ 0.13 for lift direction. The fluctuating drag and lift coefficients used in the 'design guide' were estimated to be conservative by comparison with these data. Correlation lengths for a cylinder and a taper shaped one in the high Reynolds-number region were estimated to be 1.6 times of the diameter(D) in the maximum case. The measured value of correlation length is enough smaller than the 'design guide' value of 3.0D. Displacement amplitudes of test pieces for Vr < 1.0 conditions were enough smaller (fives times) than calculated values based on the 'design guide'. Consequently, the applicability of the design guide' was confirmed in the range of experiments involving the super critical Reynolds-number region. (author)

Impact-induced soft-tissue vibrations associate with muscle activation in human landing movements: An accelerometry and EMG evaluation.

Science.gov (United States)

Fu, Weijie; Wang, Xi; Liu, Yu

2015-01-01

Previous studies have not used neurophysiological methodology to explore the damping effects on induced soft-tissue vibrations and muscle responses. This study aimed to investigate the changes in activation of the musculoskeletal system in response to soft-tissue vibrations with different applied compression conditions in a drop-jump landing task. Twelve trained male participants were instructed to perform drop-jump landings in compression shorts (CS) and regular shorts without compression (control condition, CC). Soft-tissue vibrations and EMG amplitudes of the leg within 50 ms before and after touchdown were collected synchronously. Peak acceleration of the thigh muscles was significantly lower in CS than in CC during landings from 45 or 60 cm and 30 cm heights (p soft-tissue vibration damping was associated with a decrease in muscular activity of the rectus femoris and biceps femoris muscles during drop-jump landings from different heights.

Harvesting traffic-induced vibrations for structural health monitoring of bridges

International Nuclear Information System (INIS)

Galchev, T V; McCullagh, J; Peterson, R L; Najafi, K

2011-01-01

This paper discusses the development and testing of a renewable energy source for powering wireless sensors used to monitor the structural health of bridges. Traditional power cables or battery replacement are excessively expensive or infeasible in this type of application. An inertial power generator has been developed that can harvest traffic-induced bridge vibrations. Vibrations on bridges have very low acceleration (0.1–0.5 m s −2 ), low frequency (2–30 Hz), and they are non-periodic. A novel parametric frequency-increased generator (PFIG) is developed to address these challenges. The fabricated device can generate a peak power of 57 µW and an average power of 2.3 µW from an input acceleration of 0.54 m s −2 at only 2 Hz. The generator is capable of operating over an unprecedentedly large acceleration (0.54–9.8 m s −2 ) and frequency range (up to 30 Hz) without any modifications or tuning. Its performance was tested along the length of a suspension bridge and it generated 0.5–0.75 µW of average power without manipulation during installation or tuning at each bridge location. A preliminary power conversion system has also been developed

Intensity-gradient induced Sisyphus cooling of a single atom in a localized hollow-beam trap

International Nuclear Information System (INIS)

Yin, Yaling; Xia, Yong; Ren, Ruimin; Du, Xiangli; Yin, Jianping

2015-01-01

In order to realize a convenient and efficient laser cooling of a single atom, we propose a simple and promising scheme to cool a single neutral atom in a blue-detuned localized hollow-beam trap by intensity-gradient induced Sisyphus cooling, and study the dynamic process of the intensity-gradient cooling of a single 87 Rb atom in the localized hollow-beam trap by using Monte-Carlo simulations. Our study shows that a single 87 Rb atom with a temperature of 120 μK from a magneto-optical trap (MOT) can be directly cooled to a final temperature of 4.64 μK in our proposed scheme. We also investigate the dependences of the cooling results on the laser detuning δ of the localized hollow-beam, the power RP 0 of the re-pumping laser beam, the sizes of both the localized hollow-beam and the re-pumping beam, and find that there is a pair of optimal cooling parameters (δ and RP 0 ) for an expected lowest temperature, and the cooling results strongly depend on the size of the re-pumping beam, but weakly depend on the size of the localized hollow-beam. Finally, we further study the cooling potential of our localized hollow-beam trap for the initial temperature of a single atom, and find that a single 87 Rb atom with an initial temperature of higher than 1 mK can also be cooled directly to about 6.6 μK. (paper)

Vibrational relaxation induced population inversions in laser pumped polyatomic molecules

International Nuclear Information System (INIS)

Shamah, I.; Flynn, G.; Columbia Univ., New York

1981-01-01

Conditions for population inversion in laser pumped polyatomic molecules are described. For systems which exhibit metastable vibrational population distributions, large, long lived inversions are possible even when the vibrational modes are strongly coupled by rapid collisional vibration-vibration (V-V) energy transfer. Overtone states of a hot mode are found to invert with respect to fundamental levels of a cold mode even at V-V steady state. Inversion persists for a V-T/R relaxation time. A gain of 4 m -1 for the 2ν 3 → ν 2 transition in CH 3 F (lambda approx. 15.9 μ) was found assuming a spontaneous emission lifetime of 10 s for this transition. General equations are derived which can be used to determine the magnitude of population inversion in any laser pumped, vibrationally metastable, polyatomic molecule. A discussion of factors controlling the population maxima of different vibrational states in optically pumped, V-V equilibrated metastable polyatomics is also given. (orig./WL)

Measurement of ground and nearby building vibration and noise induced by trains in a metro depot.

Science.gov (United States)

Zou, Chao; Wang, Yimin; Wang, Peng; Guo, Jixing

2015-12-01

Metro depots are where subway trains are parked and where maintenance is carried out. They usually occupy the largest ground areas in metro projects. Due to land utilization problems, Chinese cities have begun to develop over-track buildings above metro depots for people's life and work. The frequently moving trains, when going into and out of metro depots, can cause excessive vibration and noise to over-track buildings and adversely affect the living quality of the building occupants. Considering the current need of reliable experimental data for the construction of metro depots, field measurements of vibration and noise on the ground and inside a nearby 3-story building subjected to moving subway trains were conducted in a metro depot at Guangzhou, China. The amplitudes and frequency contents of velocity levels were quantified and compared. The composite A-weighted equivalent sound levels and maximum sound levels were captured. The predicted models for vibration and noise of metro depot were proposed based on existing models and verified. It was found that the vertical vibrations were significantly greater than the horizontal vibrations on the ground and inside the building near the testing line. While at the throat area, the horizontal vibrations near the curved track were remarkably greater than the vertical vibrations. The attenuation of the vibrations with frequencies above 50 Hz was larger than the ones below 50 Hz, and the frequencies of vibration transmitting to adjacent buildings were mainly within 10-50 Hz. The largest equivalent sound level generated in the throat area was smaller than the testing line one, but the instantaneous maximum sound level induced by wheels squeal, contact between wheels and rail joints as well as turnout was close to or even greater than the testing line one. The predicted models gave a first estimation for design and assessment of newly built metro depots. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of a distributed polarization-OTDR to measure two vibrations with the same frequency

Science.gov (United States)

Pan, Yun; Wang, Feng; Wang, Xiangchuan; Zhang, Mingjiang; Zhou, Ling; Sun, Zhenqing; Zhang, Xuping

2015-08-01

A polarization optical time-domain reflectometer (POTDR) can distributedly measure the vibration of fiber by detecting the vibration induced polarization variation only with a polarization analyzer. It has great potential in the monitoring of the border intrusion, structural healthy, anti-stealing of pipeline and so on, because of its simple configuration, fast response speed and distributed measuring ability. However, it is difficult to distinguish two vibrations with the same frequency for POTDR because the signal induced by the first vibration would bury the other vibration induced signal. This paper proposes a simple method to resolve this problem in POTDR by analyzing the phase of the vibration induced signal. The effectiveness of this method in distinguishing two vibrations with the same frequency for POTDR is proved by simulation.

Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration

Science.gov (United States)

Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

2016-01-01

BACKGROUND Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined. OBJECTIVE The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools. METHODS A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations. RESULTS When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it. CONCLUSIONS This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for

Parallel two-phase-flow-induced vibrations in fuel pin model

International Nuclear Information System (INIS)

Hara, Fumio; Yamashita, Tadashi

1978-01-01

This paper reports the experimental results of vibrations of a fuel pin model -herein meaning the essential form of a fuel pin from the standpoint of vibration- in a parallel air-and-water two-phase flow. The essential part of the experimental apparatus consisted of a flat elastic strip made of stainless steel, both ends of which were firmly supported in a circular channel conveying the two-phase fluid. Vibrational strain of the fuel pin model, pressure fluctuation of the two-phase flow and two-phase-flow void signals were measured. Statistical measures such as power spectral density, variance and correlation function were calculated. The authors obtained (1) the relation between variance of vibrational strain and two-phase-flow velocity, (2) the relation between variance of vibrational strain and two-phase-flow pressure fluctuation, (3) frequency characteristics of variance of vibrational strain against the dominant frequency of the two-phase-flow pressure fluctuation, and (4) frequency characteristics of variance of vibrational strain against the dominant frequency of two-phase-flow void signals. The authors conclude that there exist two kinds of excitation mechanisms in vibrations of a fuel pin model inserted in a parallel air-and-water two-phase flow; namely, (1) parametric excitation, which occurs when the fundamental natural frequency of the fuel pin model is related to the dominant travelling frequency of water slugs in the two-phase flow by the ratio 1/2, 1/1, 3/2 and so on; and (2) vibrational resonance, which occurs when the fundamental frequency coincides with the dominant frequency of the two-phase-flow pressure fluctuation. (auth.)

Sideband-cooling of trapped ytterbium-ions in the microwave regime

International Nuclear Information System (INIS)

Scharfenberger, Benedikt J.

2012-01-01

Trapped ions in a Paul trap are at present one of the most promising candidates for Quantum Information Processing (QIP). The technique that is used for this purpose in this experiment was introduced in 2001 by F. Mintert and Ch. Wunderlich. The core of this method is the use of atomic transitions in the radio- or microwave region, while a magnetic field gradient along the trap axis (where the ion chain is situated) lifts the degeneracy of the transition frequencies, such that the ions can be distinguished in frequency space; it also serves for the coupling of internal and external degrees of freedom of the ion chain. This method is called MAGIC (MAgnetic Gradient Induced Coupling). The performance of the measurements required that the apparatus of the experiment, which consists of laser sources, lambdameter, vacuum- and microwave system as well as imaging- and detection-units, had to be assembled and tested, which was an important prerequisite for the successful performance of the here described experiments. For the experiments it is advantageous to prepare the ions in an energetic state close to the motional ground state, which contributes to a reduction of the dephasing of the system while manipulating it with microwaves. By using the sideband-cooling technique to the sub-Doppler regime it is taken advantage of the fact, that ions in a linear trap are in good approximation situated in a harmonic oscillator potential and can therefore only populate discrete vibrational energy levels, whose frequency difference is given by the axial trap frequency ω z . If the system is excited by a microwave, which frequency is detuned from resonance to lower energies by a vibrational quantum, the ion looses one such phonon within each cooling-cycle. When this cycle is driven several times, the average phonon number and thus the temperature of the ion can be reduced efficiently and the ion can be initialized in a state close to the motional ground state. As sideband-cooling

Fuel Rod Vibration Measurement Method using a Flap and its Verification

Energy Technology Data Exchange (ETDEWEB)

Yoo, Joo Young; Park, Nam Gyu; Suh, Jung Min; Jeon, Kyeong Lak [KEPCO NF Co., Daejeon (Korea, Republic of)

2011-10-15

Flow-induced vibration is a critical factor for the mechanical integrity of a fuel rod. This vibration can cause leaked fuel through the mechanism, such as grid to rod fretting. To minimize the failures caused by flow-induced vibration, a robust design is needed which takes into account vibrational characteristics. That is, the spacer grid design should be developed to avoid any excessive vibration. On the one hand, if fuel rod vibration can be measured, an estimation of the excitation forces, which are a critical cause of rod failure, should be possible. Therefore, by applying an external force, flow-induced vibration can be roughly estimated when the fuel rod vibration model is used. KEPCO Nuclear Fuel developed the test loop to research flow-induced vibration as shown in Fig.1. The investigation flow-induced vibration (INFINIT) - the test facility - can measure the grid strap vibration and pressure drop of a 5x5 small scale fuel bundle. Basically, using a Laser Doppler Vibrometer (LDV), the vibration of a structure immersed in high speed fluid can be measured. Grid strap vibration is easily measured using an LDV. However, it is quite difficult to measure fuel rod vibration because of the round surface shape of the rods. In addition, measuring current method using the LDV, it was only possible to directly measure fuel rod vibration at the first row of the bundle as the rods behind the first row are obscured. To solve this problem, a thin flap, as shown in Fig. 2(a) can be used as a reflecting target, gaining access to rods within the bundle. The flap is attached to the fuel rod, as in Fig. 2(b). As a result, most of the inner rod vibration can be measured. Before using a flap to measure fuel rod vibration, a verification process was needed to show whether the LDV signal from the flap vibration provided equivalent and reliable signals. Therefore, impact testing was carried out on the fuel rod using a flap. The LDV signals were then compared with accelerometer

The Acute Effect of Local Vibration As a Recovery Modality from Exercise-Induced Increased Muscle Stiffness

Directory of Open Access Journals (Sweden)

Hervé Pournot, Jérémy Tindel, Rodolphe Testa, Laure Mathevon, Thomas Lapole

2016-03-01

Full Text Available Exercise involving eccentric muscle contractions is known to decrease range of motion and increase passive muscle stiffness. This study aimed at using ultrasound shear wave elastography to investigate acute changes in biceps brachii passive stiffness following intense barbell curl exercise involving both concentric and eccentric contractions. The effect of local vibration (LV as a recovery modality from exercise-induced increased stiffness was further investigated. Eleven subjects performed 4 bouts of 10 bilateral barbell curl movements at 70% of the one-rep maximal flexion force. An arm-to-arm comparison model was then used with one arm randomly assigned to the passive recovery condition and the other arm assigned to the LV recovery condition (10 min of 55-Hz vibration frequency and 0.9-mm amplitude. Biceps brachii shear elastic modulus measurements were performed prior to exercise (PRE, immediately after exercise (POST-EX and 5 min after the recovery period (POST-REC. Biceps brachii shear elastic modulus was significantly increased at POST-EX (+53 ± 48%; p < 0.001 and POST-REC (+31 ± 46%; p = 0.025 when compared to PRE. No differences were found between passive and LV recovery (p = 0.210. LV as a recovery strategy from exercise-induced increased muscle stiffness was not beneficial, probably due to an insufficient mechanical action of vibrations.

Modelling nuclear fuel vibrations in horizontal CANDU reactors

International Nuclear Information System (INIS)

Jagannath, D.V.; Oldaker, I.E.

1976-01-01

Flow-induced fuel vibrations in the pressure tubes of CANDU reactors are of vital interest to designers because fretting damage may result. Computer simulation is being used to study how bundles vibrate and to identify bundle design features which will reduce vibration and hence fretting. (author)

Improvement Performance of the Filling Step in Injection Mold through Vibration

Directory of Open Access Journals (Sweden)

Trejo-Hernández M.

2012-10-01

Full Text Available This paper shows the flow improvement in the filling step of the polymer injection process due to the polymer excitation though vibration. This process can be split up into three main steps: filling, pocking and cooling. Several mechanical and aesthetic properties of the finished product can be changed in the filling step. The objective of this investigation is to demonstrate the improvement in the filling mold under vibration without adding chemical products. To reach this result, an experimental mold was designed and manufactured in which a vibration device was coupled; it was possible to demonstrate the vibration advantage through this process. Moreover, a heuristic methodology was proposed for the experiment which shows an improvement in the filling process with frequencies close to 3 Hz.

The Vibration Analysis of Tube Bundles Induced by Fluid Elastic Excitation in Shell Side of Heat Exchanger

Science.gov (United States)

Bao, Minle; Wang, Lu; Li, Wenyao; Gao, Tianze

2017-09-01

Fluid elastic excitation in shell side of heat exchanger was deduced theoretically in this paper. Model foundation was completed by using Pro / Engineer software. The finite element model was constructed and imported into the FLUENT module. The flow field simulation adopted the dynamic mesh model, RNG k-ε model and no-slip boundary conditions. Analysing different positions vibration of tube bundles by selecting three regions in shell side of heat exchanger. The results show that heat exchanger tube bundles at the inlet of the shell side are more likely to be failure due to fluid induced vibration.

Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

Directory of Open Access Journals (Sweden)

Ripeng Jiang

2014-07-01

Full Text Available The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

The application of external vibration monitoring to reactors with concrete pressure vessels

International Nuclear Information System (INIS)

Hammill, W.J.

1979-01-01

The application of external vibration monitoring techniques to advanced gas cooled reactors (AGR) which have concrete pressure vessels is considered. A monitoring system for a particular AGR coolant circuit structure is developed, whose primary objective is to detect impacting of two components, although the detection of forced vibration response is also considered. Experimental results from instrumented components in the reactor and data from rig tests on full size units have been used together with a mathematical model of some elements of the transmission path in order to establish its dynamic characteristics and relate internal component vibration to externally measured signals. The application of external vibration monitoring to the external detection of the forced vibration response of an internal reactor assembly and the remote monitoring of circulator sound output is discussed. (author)

Fluid-induced vibration of composite natural gas pipelines

Energy Technology Data Exchange (ETDEWEB)

Zou, G.P.; Cheraghi, N.; Taheri, F. [Dalhousie Univ., Dept. of Civil Engineering, Halifax, NS (Canada)

2005-02-01

Advancements in materials bonding techniques have led to the use of reinforced composite pipelines. The use of steel pipe with a fiber-reinforced composite over-wrap together has produced an exceptionally strong pipe with positive advantages in weight and corrosion resistivity. Understanding the dynamic characteristics of this kind of sub-sea composite pipelines, which often accommodate axial flow of gas, and prediction of their response is of great interest. This paper presents a state-variable model developed for the analysis of fluid-induced vibration of composite pipeline systems. Simply supported, clamped and clamped-simply supported pipelines are investigated. The influence of fluid's Poisson ratio, the ratio of pipe radius to pipe-wall thickness, laminate layup, the ratio of liquid mass density to pipe-wall mass density, the fluid velocity, initial tension and fluid pressure are all considered. The results of our proposed methodology are compared with those of finite element analysis, using ANSYS ssoftware. (Author)

Parameterization of typhoon-induced ocean cooling using temperature equation and machine learning algorithms: an example of typhoon Soulik (2013)

Science.gov (United States)

Wei, Jun; Jiang, Guo-Qing; Liu, Xin

2017-09-01

This study proposed three algorithms that can potentially be used to provide sea surface temperature (SST) conditions for typhoon prediction models. Different from traditional data assimilation approaches, which provide prescribed initial/boundary conditions, our proposed algorithms aim to resolve a flow-dependent SST feedback between growing typhoons and oceans in the future time. Two of these algorithms are based on linear temperature equations (TE-based), and the other is based on an innovative technique involving machine learning (ML-based). The algorithms are then implemented into a Weather Research and Forecasting model for the simulation of typhoon to assess their effectiveness, and the results show significant improvement in simulated storm intensities by including ocean cooling feedback. The TE-based algorithm I considers wind-induced ocean vertical mixing and upwelling processes only, and thus obtained a synoptic and relatively smooth sea surface temperature cooling. The TE-based algorithm II incorporates not only typhoon winds but also ocean information, and thus resolves more cooling features. The ML-based algorithm is based on a neural network, consisting of multiple layers of input variables and neurons, and produces the best estimate of the cooling structure, in terms of its amplitude and position. Sensitivity analysis indicated that the typhoon-induced ocean cooling is a nonlinear process involving interactions of multiple atmospheric and oceanic variables. Therefore, with an appropriate selection of input variables and neuron sizes, the ML-based algorithm appears to be more efficient in prognosing the typhoon-induced ocean cooling and in predicting typhoon intensity than those algorithms based on linear regression methods.

Study and analysis on the flow induced vibration of the core barrel of PWR

International Nuclear Information System (INIS)

Yao Weida; Shi Guolin; Jiang Nanyan; Peng YongYong; Zhang Huijun; Wang Yufen; Xie Yongcheng; Guo Chunhua; Shen Qinping

1989-01-01

The deduction of the resemblance criterion and the design of the test model by applying flow-solid coupling theory are described. The model analysis of a core barrel both in the air and stationary water were performed in a 1:10 model, thus obtaining the dynamic characteristic. In a 1:5 reactor model with a hydraulic closed loop, the inner structure and support were modeled for performing hydraulic closed loop, the inner structure and support were modeled for performing hydraulic vibration test of the core barrel. The flow induced pulse pressure of the core barrel and corresponding response were obtained by using miniature pressure capsule, strain gauge and accelerometer. Power spectrum, correlation functions, transfer function and amplitudes under different flow velocities were calculated. The hydraulic vibration test shows that the core barrel will be in safety during its 30-year life time

Estimation of the effects of rain-wind induced vibration in the design stage of inclined stay cables

NARCIS (Netherlands)

Geurts, C.P.W.; Staalduinen, P.C. van

1999-01-01

Rain-wind induced vibration of stay cables is a great concern for the designers of cable stayed bridges. Despite numerous experimental investigations, an accurate quantitative prediction of this effect in the design stage is not feasible without extensive experiments. This paper presents a model to

Prototype observation and influencing factors of environmental vibration induced by flood discharge

Directory of Open Access Journals (Sweden)

Xin Wang

2017-01-01

Full Text Available Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The results indicate that field vibrations caused by flood discharge have distinctive characteristics of constancy, low frequency, small amplitude, and randomness with impact, which significantly differ from the common high-frequency vibration characteristics. Field vibrations have a main frequency of about 0.5–3.0 Hz and the characteristics of long propagation distance and large-scale impact. The vibration of a stilling basin slab runs mainly in the vertical direction. The vibration response of the guide wall perpendicular to the flow is significantly stronger than it is in other directions and decreases linearly downstream along the guide wall. The vibration response of the underground turbine floor is mainly caused by the load of unit operation. Urban environmental vibration has particular distribution characteristics and change patterns, and is greatly affected by discharge, scheduling modes, and geological conditions. Along with the increase of the height of residential buildings, vibration responses show a significant amplification effect. The horizontal and vertical vibrations of the 7th floor are, respectively, about 6 times and 1.5 times stronger than the corresponding vibrations of the 1st floor. The vibration of a large-scale chemical plant presents the combined action of flood discharge and working machines. Meanwhile, it is very difficult to reduce the low-frequency environmental vibrations. Optimization of the discharge scheduling mode is one of the effective measures of reducing the flow impact loads at present. Choosing reasonable dam sites is crucial.

Observation of the v′=8←v=0 vibrational overtone in cold trapped HD +

NARCIS (Netherlands)

J.C.J. Koelemeij; D.W.E. Noom; D. de Jong; M.A. Haddad; W. Ubachs

2011-01-01

textabstractWe report the observation of the hitherto undetected v′=8←v=0 vibrational overtone in trapped HD+molecular ions, sympathetically cooled by laser-cooled Be+ions. The overtone is excited using 782 nm laser radiation, after which HD+ions in v=8 are photodissociated by the 313 nm laser used

Embedding human annoyance rate models in wireless smart sensors for assessing the influence of subway train-induced ambient vibration

Science.gov (United States)

Sun, Ke; Zhang, Wei; Ding, Huaping; Kim, Robin E.; Spencer, Billie F., Jr.

2016-10-01

The operation of subway trains induces ambient vibrations, which may cause annoyance and other adverse effects on humans, eventually leading to physical, physiological, and psychological problems. In this paper, the human annoyance rate (HAR) models, used to assess the human comfort under the subway train-induced ambient vibrations, were deduced and the calibration curves for 5 typical use circumstances were addressed. An autonomous measurement system, based on the Imote2, wireless smart sensor (WSS) platform, plus the SHM-H, high-sensitivity accelerometer board, was developed for the HAR assessment. The calibration curves were digitized and embedded in the computational core of the WSS unit. Experimental validation was conducted, using the developed system on a large underground reinforced concrete frame structure adjoining the subway station. The ambient acceleration of both basement floors was measured; the embedded computation was implemented and the HAR assessment results were wirelessly transmitted to the central server, all by the WSS unit. The HAR distributions of the testing areas were identified, and the extent to which both basements will be influenced by the close-up subway-train’s operation, in term of the 5 typical use circumstances, were quantitatively assessed. The potential of the WSS-based autonomous system for the fast environment impact assessment of the subway train-induced ambient vibration was well demonstrated.

Parametric Study and Optimization of a Piezoelectric Energy Harvester from Flow Induced Vibration

Science.gov (United States)

Ashok, P.; Jawahar Chandra, C.; Neeraj, P.; Santhosh, B.

2018-02-01

Self-powered systems have become the need of the hour and several devices and techniques were proposed in favour of this crisis. Among the various sources, vibrations, being the most practical scenario, is chosen in the present study to investigate for the possibility of harvesting energy. Various methods were devised to trap the energy generated by vibrating bodies, which would otherwise be wasted. One such concept is termed as flow-induced vibration which involves the flow of a fluid across a bluff body that oscillates due to a phenomenon known as vortex shedding. These oscillations can be converted into electrical energy by the use of piezoelectric patches. A two degree of freedom system containing a cylinder as the primary mass and a cantilever beam as the secondary mass attached with a piezoelectric circuit, was considered to model the problem. Three wake oscillator models were studied in order to determine the one which can generate results with high accuracy. It was found that Facchinetti model produced better results than the other two and hence a parametric study was performed to determine the favourable range of the controllable variables of the system. A fitness function was formulated and optimization of the selected parameters was done using genetic algorithm. The parametric optimization led to a considerable improvement in the harvested voltage from the system owing to the high displacement of secondary mass.

Interaction of spin and vibrations in transport through single-molecule magnets.

Science.gov (United States)

May, Falk; Wegewijs, Maarten R; Hofstetter, Walter

2011-01-01

We study electron transport through a single-molecule magnet (SMM) and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.

Vibrations on board and health effects

DEFF Research Database (Denmark)

Jensen, Anker; Jepsen, Jørgen Riis

2014-01-01

There is only limited knowledge of the exposure to vibrations of ships’ crews and their risk of vibration-induced health effects. Exposure to hand-arm vibrations from the use of vibrating tools at sea does not differ from that in the land-based trades. However, in contrast to most other work places...... of the health consequences of whole body vibrations in land-transportation, such exposure at sea may affect ships’ passengers and crews. While the relation of back disorders to high levels of whole body vibration has been demonstrated among e.g. tractor drivers, there are no reported epidemiological evidence...... for such relation among seafarers except for fishermen, who, however, are also exposed to additional recognised physical risk factors at work. The assessment and reduction of vibrations by naval architects relates to technical implications of this impact for the ships’ construction, but has limited value...

Hydrodynamics induced vibration to trash-racks

International Nuclear Information System (INIS)

Sadrnejad, A.

2002-01-01

In conventional power plants trash-racks are provided at the intakes to protect the turbines. In pumped storage plants, the draft tube or tailrace must also have trash-racks to protect the units while pumping. Because the loads believed to cause many failures of trash-racks are dynamic in nature, it is important to understand the dynamic characteristics of trash-racks structures in general and a single rack in particular. The classical added-mass solution structure-fluid dynamic interaction is known as an approximate solution procedure. An accurate added-mass approach mixed with implementation in finite element framework is proposed. In this proposal, experimental conclusions, supported by theory, led to presentation of more accurate results in vibration of trash-racks. This numerical solution as a powerful method to solve such a complex problem can be employed to carry out dynamic characteristics of these structures while vibrating in water

Equivalence of Electron-Vibration Interaction and Charge-Induced Force Variations: A New O(1 Approach to an Old Problem

Directory of Open Access Journals (Sweden)

Tunna Baruah

2012-04-01

Full Text Available Calculating electron-vibration (vibronic interaction constants is computationally expensive. For molecules containing N nuclei it involves solving the Schrödinger equation for Ο(3N nuclear configurations in addition to the cost of determining the vibrational modes. We show that quantum vibronic interactions are proportional to the classical atomic forces induced when the total charge of the system is varied. This enables the calculation of vibronic interaction constants from O(1 solutions of the Schrödinger equation. We demonstrate that the O(1 approach produces numerically accurate results by calculating the vibronic interaction constants for several molecules. We investigate the role of molecular vibrations in the Mott transition in κ-(BEDT-TTF2Cu[N(CN2]Br.

Fluidelastic vibration of cylinder arrays in axial and cross flow--state of the art

International Nuclear Information System (INIS)

Paidoussis, M.P.

1981-01-01

A critical assessment of the state of the art for flow-induced vibrations of cylinder arrays in cross and axial flow is presented. An historical review highlights the contributions which advanced understanding of the flow-induced vibration phenomena involved and/or predictive ability. In the case of axial-flow-induced vibration, the absence of separated flow regions has contributed towards the development of analytical predictive tools. The designer may predict the onset of fluidelastic instabilities, which generally occur at very high flow velocities, with greater confidence. In contrast, in the case of cross-flow-induced vibration, the complexity of the flow has encouraged more heuristic approaches to be adopted. The state of the art in this case is discussed with the aid of a new classification of the flow-induced vibration phenomena involved, to unify and clarify the contradictory claims facing the designer. It is concluded that, although the physical understanding of cross-flow-induced vibration phenomena is not good, useful design guidelines do exist. These are capable of predicting vibration characteristics to within a factor of 2 to 10. A comprehensive bibliography is included. 115 refs

Mitigating ground vibration by periodic inclusions and surface structures

DEFF Research Database (Denmark)

Andersen, Lars Vabbersgaard; Bucinskas, Paulius; Persson, Peter

2016-01-01

Ground vibration from traffic is a source of nuisance in urbanized areas. Trenches and wave barriers can provide mitigation of vibrations, but single barriers need to have a large depth to be effective-especially in the low-frequency range relevant to traffic-induced vibration. Alternatively...

Flow induced vibrations in a PWR piping system

International Nuclear Information System (INIS)

Seligmann, D.C.; Guillou, J.P.

1995-01-01

In this paper, we present and industrial study of the dynamic behaviour of the piping system of a French 1300 M We nuclear power plant. High-amplitude vibrations had been noticed on a safeguard system during the periodical operation startup tests. These vibrations, due to acoustical pump sources, cause fatigue-damage and it is therefore necessary to propose an estimation of the service-life of the piping and to propose modification of piping system to reduce vibrations. First, we define a mechanical model readjusted according to gauged vibratory speeds and construct a vibro-acoustic coupled model and a pump-behaviour model as a source of excitation. Second, we simulate a modification of the supports. The influence of this modification is analysed by comparison of the root mean square values of vibratory speeds and the stresses between the initial system and the modified system. 3 refs., 7 figs

Flow induced vibration of secondary piping of LMFBR

International Nuclear Information System (INIS)

Gibert, R.J.; Axisa, F.

1977-01-01

This paper presents a method for evaluating the characteristics of vibrations caused by internal flow in three-dimensional piping systems conveying high density fluids. The excitation of the circuit is mainly caused by the flow singularities, and it is shown that the problem may be reduced to calculate the response of the circuit to an acoustical pressure discontinuity, localised at each flow singularity. The paper is divided into two main parts: First part is devoted to the theoretical formulation of the coupled acoustical-mechanical problem and to its numerical solution by the french computer code TEDEL. Second part describes an experimental test of the method. The tested piping system consists of a stainless steel tube circuit comprising four 909 bends, conveying water. Vibrations are excited by a half closed gate valve. Satisfactory results are obtained concerning both the frequencies of resonance of the circuit and the level of the vibrations observed

SBIR Grant:No-Vibration Agile Cryogenic Optical Refrigerator

Energy Technology Data Exchange (ETDEWEB)

Epstein, Richard

2013-04-09

Optical refrigeration is currently the only all-solid-state cryocooling technology that has been demonstrated. Optical cryocoolers are devices that use laser light to cool small crystal or glass cooling elements. The cooling element absorbs the laser light and reradiates it at higher energy, an example of anti-Stokes fluorescence. The dif-ference between the energy of the outgoing and incoming light comes from the thermal energy of the cooling element, which in turn becomes colder. Entitled No-Vibration Agile Cryocoolers using Optical Refrigeration, this Phase I proposal directly addressed the continued development of the optical refrigerator components necessary to transition this scientific breakthrough into National Nu-clear Security Administration (NNSA) sensor applications in line with the objectives of topic 50b. ThermoDynamic Films LLC (TDF), in collaboration with the University of New Mexico (UNM), cooled an optical-refrigerator cooling element comprised of an ytterbium-doped yttrium lithium fluoride (Yb:YLF) crystal from room tempera-ture to 123 K with about 2% efficiency. This is the world record in optical refrigera-tion and an important step toward revolutionizing cryogenic systems for sensor ap-plications. During this period, they also designed and analyzed the crucial elements of a prototype optical refrigerator including the thermal link that connects the cool-ing element with the load.

Bubbling behavior of a fluidized bed of fine particles caused by vibration-induced air inflow.

Science.gov (United States)

Matsusaka, Shuji; Kobayakawa, Murino; Mizutani, Megumi; Imran, Mohd; Yasuda, Masatoshi

2013-01-01

We demonstrate that a vibration-induced air inflow can cause vigorous bubbling in a bed of fine particles and report the mechanism by which this phenomenon occurs. When convective flow occurs in a powder bed as a result of vibrations, the upper powder layer with a high void ratio moves downward and is compressed. This process forces the air in the powder layer out, which leads to the formation of bubbles that rise and eventually burst at the top surface of the powder bed. A negative pressure is created below the rising bubbles. A narrow opening at the bottom allows the outside air to flow into the powder bed, which produces a vigorously bubbling fluidized bed that does not require the use of an external air supply system.

Low frequency vibrations induce malformations in two aquatic species in a frequency-, waveform-, and direction-specific manner.

Directory of Open Access Journals (Sweden)

Laura N Vandenberg

Full Text Available Environmental toxicants such as industrial wastes, air particulates from machinery and transportation vehicles, and pesticide run-offs, as well as many chemicals, have been widely studied for their effects on human and wildlife populations. Yet other potentially harmful environmental pollutants such as electromagnetic pulses, noise and vibrations have remained incompletely understood. Because developing embryos undergo complex morphological changes that can be affected detrimentally by alterations in physical forces, they may be particularly susceptible to exposure to these types of pollutants. We investigated the effects of low frequency vibrations on early embryonic development of two aquatic species, Xenopus laevis (frogs and Danio rerio (zebrafish, specifically focusing on the effects of varying frequencies, waveforms, and applied direction. We observed treatment-specific effects on the incidence of neural tube defects, left-right patterning defects and abnormal tail morphogenesis in Xenopus tadpoles. Additionally, we found that low frequency vibrations altered left-right patterning and tail morphogenesis, but did not induce neural tube defects, in zebrafish. The results of this study support the conclusion that low frequency vibrations are toxic to aquatic vertebrates, with detrimental effects observed in two important model species with very different embryonic architectures.

Investigation of the integrity of u-bend tube bundles subjected to flow-induced vibrations

Energy Technology Data Exchange (ETDEWEB)

Hassan, M. [University of Guelph, Guelph, Ontario (Canada); Riznic, J. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada)

2012-07-01

Maintaining the integrity of nuclear steam generator (SG) tubes in CANDU reactors is a major safety issue since they maintain the physical barrier between the primary and secondary coolants. The integrity of these tubes can be compromised due to flow-induced vibrations in the form of fatigue and fretting wear damage. Wear is a result of the tube impacting and sliding against its loose supports, and it becomes more severe as the tube/support clearance increases. The vibration is caused by fluid flow around these tubes through turbulence and fluidelastic instability mechanisms. Supports are installed to stiffen the structure and to ensure safe and stable operation. The U-bend region is the most critical part since it is subjected to high cross flow. Therefore, special attention is paid to properly supporting this region. However, in some situations, tube support plates (TSP) located on the straight part of the tube may deteriorate to the point where extremely large clearances, or even total wastage of the supports, may result. One possible cause for such a situation is corrosion and/or excessive fretting wear. This loss of TSP may affect the rate of wear in the U-bend portion of the tube due to the increased flexibility in this region. The integrity could be seriously breached as result of a potential support loss. This paper addresses the flow-induced vibrations (FIV) aspect, consequences, and suggested remedies for support degradation. This analysis will include fretting wear producing parameters, such as impact force and normal work rate. Turbulence and fluidelastic instability (FEI) are considered to be the main excitation mechanisms. The investigation is conducted through a numerical simulation of the full Ubend tube bundles including modelling the variable flow distribution, flow excitation, impact, and friction at the supports. (author)

Interaction of spin and vibrations in transport through single-molecule magnets

Directory of Open Access Journals (Sweden)

Falk May

2011-10-01

Full Text Available We study electron transport through a single-molecule magnet (SMM and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.

On the Shaker Simulation of Wind-Induced Non-Gaussian Random Vibration

Directory of Open Access Journals (Sweden)

Fei Xu

2016-01-01

Full Text Available Gaussian signal is produced by ordinary random vibration controllers to test the products in the laboratory, while the field data is usually non-Gaussian. Two methodologies are presented in this paper for shaker simulation of wind-induced non-Gaussian vibration. The first methodology synthesizes the non-Gaussian signal offline and replicates it on the shaker in the Time Waveform Replication (TWR mode. A new synthesis method is used to model the non-Gaussian signal as a Gaussian signal multiplied by an amplitude modulation function (AMF. A case study is presented to show that the synthesized non-Gaussian signal has the same power spectral density (PSD, probability density function (PDF, and loading cycle distribution (LCD as the field data. The second methodology derives a damage equivalent Gaussian signal from the non-Gaussian signal based on the fatigue damage spectrum (FDS and the extreme response spectrum (ERS and reproduces it on the shaker in the closed-loop frequency domain control mode. The PSD level and the duration time of the derived Gaussian signal can be manipulated for accelerated testing purpose. A case study is presented to show that the derived PSD matches the damage potential of the non-Gaussian environment for both fatigue and peak response.

Development of monitoring system using acoustic emission for detection of helium gas leakage for primary cooling system and flow-induced vibration for heat transfer tube of heat exchangers for the High Temperature Engineering Test Reactor (HTTR)

International Nuclear Information System (INIS)

Tachibana, Yukio; Kunitomi, Kazuhiko; Furusawa, Takayuki; Shinozaki, Masayuki; Satoh, Yoshiyuki; Yanagibashi, Minoru

1998-10-01

The High Temperature Engineering Test Reactor (HTTR) uses helium gas for its primary coolant, whose leakage inside reactor containment vessel is considered in design of the HTTR. It is necessary to detect leakage of helium gas at an early stage so that total amount of the leakage should be as small as possible. On the other hand, heat transfer tubes of heat exchangers of the HTTR are designed not to vibrate at normal operation, but the flow-induced vibration is to be monitored to provide against an emergency. Thus monitoring system of acoustic emission for detection of primary coolant leakage and vibration of heat transfer tubes was developed and applied to the HTTR. Before the application to the HTTR, leakage detection test was performed using 1/4 scaled model of outer tube of primary concentric hot gas duct. Result of the test covers detectable minimum leakage rate and effect of difference in gas, pressure, shape of leakage path and distance from the leaking point. Detectable minimum leakage rate was about 5 Ncc/sec. The monitoring system is promising in leakage detection, though countermeasure to noise is to be needed after the HTTR starts operating. (author)

Experience in WWER fuel assemblies vibration analysis

International Nuclear Information System (INIS)

Ovtcharov, O.; Pavelko, V.; Usanov, A.; Arkadov, G.; Dolgov, A.; Molchanov, V.

2003-01-01

It is stated that the vibration studies of internals and the fuel assemblies should be conducted during the reactor designing, commissioning and commercial operation stages and the analysis methods being used should complement each other. The present paper describes the methods and main results of the vibration noise studies of internals and the fuel assemblies of the operating NPPs with WWER reactors, as an example of the implementation of the comprehensive approach to the analysis on equipment flow-induced vibration. At that, the characteristics of internals and fuel assemblies vibration loading were dealt jointly as they are elements of the same compound oscillating system and their vibrations have the interrelated nature

The integration of cryogenic cooling systems with superconducting electronic systems

International Nuclear Information System (INIS)

Green, Michael A.

2003-01-01

The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

A proposal for Coulomb assisted laser cooling of piezoelectric semiconductors

Energy Technology Data Exchange (ETDEWEB)

Nia, Iman Hassani; Mohseni, Hooman, E-mail: hmohseni@ece.northwestern.edu [Bio-Inspired Sensors and Optoelectronics Laboratory (BISOL), Department of Electrical Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

2014-07-28

Anti-Stokes laser cooling of semiconductors as a compact and vibration-free method is very attractive. While it has achieved significant milestones, increasing its efficiency is highly desirable. The main limitation is the lack of the pristine material quality with high luminescence efficiency. Here, we theoretically demonstrate that the Coulomb interaction among electrons and holes in piezoelectric heterostructures could lead to coherent damping of acoustic phonons; rendering a significantly higher efficiency that leads to the possibility of cooling a broad range of semiconductors.

Numerical solution for gate induced vibration due to under flow cavitation

International Nuclear Information System (INIS)

Sadrnezhad, S. A.

2001-01-01

Among the many forces to which hydraulic structures are exposed to, the forces induced by cavitation incident are of typical hydrodynamic unknown forces. The aim of this study is to define these forces as coupled fluid-structure interaction under two dynamic effects. The first dynamic effect which incorporates facilities for dealing with cavitation fluid is based on the appearance and bursting of vapor bubbles. The second hydrodynamic effect is dynamic excitation mechanism of the structure. In fluid-structure interaction, both the structure behavior and fluid are considered linear. Fluids can take some tension the extent of which depends on concentration and size of micro bubbles present; nevertheless, if the absolute pressure drops to a value close to the vapor pressure of the fluid, bubbles are formed and cavitation phenomena occurs. In this paper a fixed-wheel gate under the head pressure of a reservoir is considered to be affected by under flow cavitation. Normally, partially opened gates induce energy dissipation resulting in high turbulence, causing negative pressure and cavitation at the back and this exits the gate vibration. Moreover, there are several mechanisms which may cause heavy, self-excited vibration. According to the proposed method, a time function presenting the oscillation and pressure fluctuation in the vicinity of gate lip is estimated. This estimation is based on the parameters obtained from a two dimensional solution of flow under the gate lip. Accordingly, periodic time variable nodal forces are calculated and applied to gate lip element nodes. A transient dynamic solution of the gate, while its lip is sustaining nodal forces is estimated as time function. The results for the most server modal deformation of the structure time history of some critical elements and variation of equivalent force versus time are presented

New algorithm for controlling electric arc furnaces using their vibrational and acoustic characteristics

Science.gov (United States)

Cherednichenko, V. S.; Bikeev, R. A.; Serikov, V. A.; Rechkalov, A. V.; Cherednichenko, A. V.

2016-12-01

The processes occurring in arc discharges are analyzed as the sources of acoustic radiation in an electric arc furnace (EAF). Acoustic vibrations are shown to transform into mechanical vibrations in the furnace laboratory. The shielding of the acoustic energy fluxes onto water-cooled wall panels by a charge is experimentally studied. It is shown that the rate of charge melting and the depth of submergence of arc discharges in the slag and metal melt can be monitored by measuring the vibrational characteristics of furnaces and using them in a universal industrial process-control system, which was developed for EAFs.

Vibration test report on the instrumented capsule for fuel irradiation test

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jeong Soo; Yoon, D. B.; Wu, J. S.; Oh, J. M.; Park, S. J.; Cho, M. S.; Kim, B. G.; Kang, Y. W

2003-01-01

The fluid-induced vibration level of instrumented capsule, which was manufactured for fuel irradiation test at the reactor core of HANARO, was investigated. For this purpose, the instrumented capsule was loaded at the OR site of the HANARO design verification test facility that could simulate identical flow condition as the HANARO core. Then, vibration signals of the instrumented capsule subjected to various flow conditions were measured by using vibration sensors. In time domain analysis, maximum amplitudes and RMS values of the measured acceleration and displacement signals were obtained. By using frequency domain analysis, frequency components of the fluid-induced vibration were analyzed. In addition, natural frequencies of the instrumented capsule were obtained by performing modal test. The frequency analysis results showed that the natural frequency components near 7.5Hz and 17.5Hz were dominant in the fluid-induced vibration signal. The maximum amplitude of the accelerations was measured as 12.04m/s{sup 2} that is within the allowable vibrational limit(18.99m/s{sup 2})of the reactor structure. Also, the maximum displacement amplitude was calculated as 0.191mm. Since these vibration levels are remarkably low, excessive vibration is not expected when the irradiation test of the instrumented capsule is performed at the HANARO core.

Axial Fan Blade Vibration Assessment under Inlet Cross-Flow Conditions Using Laser Scanning Vibrometry

Directory of Open Access Journals (Sweden)

Till Heinemann

2017-08-01

Full Text Available In thermal power plants equipped with air-cooled condensers (ACCs, axial cooling fans operate under the influence of ambient flow fields. Under inlet cross-flow conditions, the resultant asymmetric flow field is known to introduce additional harmonic forces to the fan blades. This effect has previously only been studied numerically or by using blade-mounted strain gauges. For this study, laser scanning vibrometry (LSV was used to assess fan blade vibration under inlet cross-flow conditions in an adapted fan test rig inside a wind tunnel test section. Two co-rotating laser beams scanned a low-pressure axial fan, resulting in spectral, phase-resolved surface vibration patterns of the fan blades. Two distinct operating points with flow coefficients of 0.17 and 0.28 were examined, with and without inlet cross-flow influence. While almost identical fan vibration patterns were found for both reference operating points, the overall blade vibration increased by 100% at the low fan flow rate as a result of cross-flow, and by 20% at the high fan flow rate. While numerically predicted natural frequency modes could be confirmed from experimental data as minor peaks in the vibration amplitude spectrum, they were not excited significantly by cross-flow. Instead, primarily higher rotation-rate harmonics were amplified; that is, a synchronous blade-tip flapping was strongly excited at the blade-pass frequency.

[The adaptive capacities of the cardiovascular system in miners exposed to vibration].

Science.gov (United States)

Konevskikh, L A; Oranskiĭ, I E; Makogon, I S

2013-01-01

Diagnostics criteria for work-related adaptation disorders in respect of cardiovascular system factors have been developed; the stages of disadaptation have been characterized through the example of vibration exposed miners working under the conditions of cool microclimate.

Whole body vibration improves attention and motor performance in ...

African Journals Online (AJOL)

Background: Whole body vibration (WBV) is a form of physical stimulation via mechanical vibrations transmitted to a subject. It is assumed that WBV induces sensory stimulation in cortical brain regions through the activation of skin and muscle receptors responding to the vibration. The effects of WBV on muscle strength are ...

Laser-induced breakdown spectroscopy with laser irradiation resonant with vibrational transitions

International Nuclear Information System (INIS)

Khachatrian, Ani; Dagdigian, Paul J.

2010-01-01

An investigation of laser-induced breakdown spectroscopy (LIBS) of polymers, both in bulk form and spin coated on Si wafers, with laser irradiation in the mid-infrared spectral region is presented. Of particular interest is whether the LIBS signals are enhanced when the laser wavelength is resonant with a fundamental vibrational transition of the polymer. Significant increases in the LIBS signals were observed for irradiation on hydride stretch fundamental transitions, and the magnitude of the enhancement showed a strong dependence on the mode excited. The role of the substrate was investigated by comparison of results for bulk and spin-coated samples. The polymers investigated were Nylon 12 and poly(vinyl alcohol-co-ethylene).

Physiologic and Perceptual Responses to Cold-Shower Cooling After Exercise-Induced Hyperthermia.

Science.gov (United States)

Butts, Cory L; McDermott, Brendon P; Buening, Brian J; Bonacci, Jeffrey A; Ganio, Matthew S; Adams, J D; Tucker, Matthew A; Kavouras, Stavros A

2016-03-01

Exercise conducted in hot, humid environments increases the risk for exertional heat stroke (EHS). The current recommended treatment of EHS is cold-water immersion; however, limitations may require the use of alternative resources such as a cold shower (CS) or dousing with a hose to cool EHS patients. To investigate the cooling effectiveness of a CS after exercise-induced hyperthermia. Randomized, crossover controlled study. Environmental chamber (temperature = 33.4°C ± 2.1°C; relative humidity = 27.1% ± 1.4%). Seventeen participants (10 male, 7 female; height = 1.75 ± 0.07 m, body mass = 70.4 ± 8.7 kg, body surface area = 1.85 ± 0.13 m(2), age range = 19-35 years) volunteered. On 2 occasions, participants completed matched-intensity volitional exercise on an ergometer or treadmill to elevate rectal temperature to ≥39°C or until participant fatigue prevented continuation (reaching at least 38.5°C). They were then either treated with a CS (20.8°C ± 0.80°C) or seated in the chamber (control [CON] condition) for 15 minutes. Rectal temperature, calculated cooling rate, heart rate, and perceptual measures (thermal sensation and perceived muscle pain). The rectal temperature (P = .98), heart rate (P = .85), thermal sensation (P = .69), and muscle pain (P = .31) were not different during exercise for the CS and CON trials (P > .05). Overall, the cooling rate was faster during CS (0.07°C/min ± 0.03°C/min) than during CON (0.04°C/min ± 0.03°C/min; t16 = 2.77, P = .01). Heart-rate changes were greater during CS (45 ± 20 beats per minute) compared with CON (27 ± 10 beats per minute; t16 = 3.32, P = .004). Thermal sensation was reduced to a greater extent with CS than with CON (F3,45 = 41.12, P < .001). Although the CS facilitated cooling rates faster than no treatment, clinicians should continue to advocate for accepted cooling modalities and use CS only if no other validated means of cooling are available.

Mechanics and cooling of the Mu3e detector

Energy Technology Data Exchange (ETDEWEB)

Austermuehl, Rene Philipp; Henkelmann, Lars; Herkert, Adrian; Ng, Yanwing [Physikalisches Institut, Uni Heidelberg (Germany); Collaboration: Mu3e-Collaboration

2016-07-01

The Mu3e experiment will search for the charged lepton flavour violating decay μ{sup +} → e{sup +}e{sup -}e{sup +}, which is suppressed to unobservable levels in the Standard Model. A signal would be a clear sign of new physics. The aim is to reach a sensitivity for the branching ratio of 10{sup -16}, which requires high momentum resolution. Since the muons will decay at rest on target, the energy of the decay electrons will be E≤53 MeV. In this energy regime the momentum resolution is limited by multiple scattering in the detector material. Therefore, the Mu3e detector, including support structure and services, has to consist of as little material as possible in the active region. The main component of the detector is a pixel tracker consisting of four barrels of high voltage monolithic active pixel sensors (HV-MAPS) that can be thinned to 50 μm. A power consumption of 400 mW/cm{sup 2} is expected. To keep the material budget low, it is planned to cool with gaseous helium. In this talk results of computational fluid dynamics simulations of the Mu3e cooling system and experimental tests concerning the detector's stability against flow-induced vibrations are presented.

Cooling of electronic equipment

DEFF Research Database (Denmark)

A. Kristensen, Anders Schmidt

2003-01-01

Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...

Heating up the gas cooling market

International Nuclear Information System (INIS)

Watt, G.

2001-01-01

Gas cooling is an exciting technology with a potentially bright future. It comprises the production of cooling (and heating) in buildings and industry, by substituting environmentally-friendlier natural gas or LPG over predominantly coal-fired electricity in air conditioning equipment. There are currently four established technologies using gas to provide cooling energy or conditioned air. These are: absorption, both direct gas-fired and utilising hot water or steam; gas engine driven vapour compression (GED); cogeneration, with absorption cooling driven by recovered heat; and desiccant systems. The emergence of gas cooling technologies has been, and remains, one of evolution rather than revolution. However, further development of the technology has had a revolutionary effect on the performance, reliability and consumer acceptability of gas cooling products. Developments from world-renowned manufacturers such as York, Hitachi, Robur and Thermax have produced a range of absorption equipment variously offering: the use of 100 percent environmentally-friendly refrigerants, with zero global warming potential; the ideal utilisation of waste heat from cogeneration systems; a reduction in electrical distribution and stand-by generation capacity; long product life expectancy; far less noise and vibration; performance efficiency maintained down to about 20 percent of load capacity; and highly automated and low-cost maintenance. It is expected that hybrid systems, that is a mixture of gas and electric cooling technologies, will dominate the future market, reflecting the uncertainty in the electricity market and the prospects of stable future gas prices

Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

Science.gov (United States)

Yang, Yang; Pan, Yayue; Guo, Ping

2017-04-01

Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

Vibrational polarizabilities of hydrogen-bonded water

International Nuclear Information System (INIS)

Torii, Hajime

2013-01-01

Highlights: ► Vibrational polarizabilities of hydrogen-bonded water are analyzed theoretically. ► Total vibrational polarizability is (at least) comparable to the electronic one. ► Molecular translations contribute to the vibrational polarizability below 300 cm −1 . ► Intermolecular charge fluxes along H bonds are induced by molecular translations. ► The results are discussed in relation to the observed dielectric properties. - Abstract: The vibrational polarizabilities and the related molecular properties of hydrogen-bonded water are analyzed theoretically, taking the case of (water) 30 clusters as an example case. It is shown that some off-diagonal dipole derivatives are large for the translations of incompletely hydrogen-bonded molecules, and this is reasonably explained by the scheme of intermolecular charge fluxes induced along hydrogen bonds. In total, because of these intermolecular charge fluxes, molecular translations give rise to the vibrational polarizability of 2.8–3.3 a 0 3 per molecule, which is as large as about 40% of the electronic polarizability, mainly in the frequency region below 300 cm −1 . Adding the contributions of the molecular rotations (librations) and the translation–rotation cross term, the total polarizability (electronic + vibrational) at ∼100 cm −1 is slightly larger than the double of that at >4000 cm −1 . The relation of these results to some observed time- and frequency-dependent dielectric properties of liquid water is briefly discussed

[The Effectiveness of Cooling Packaging Care in Relieving Chemotherapy-Induced Skin Toxicity Reactions in Cancer Patients Receiving Chemotherapy: A Systematic Review].

Science.gov (United States)

Hsu, Ya-Hui; Hung, Hsing-Wei; Chen, Shu-Ching

2017-08-01

Anti-cancer chemotherapy may cause skin-toxicity reactions. Different types of cooling packages affect chemotherapy-induced skin toxicity reactions differently. To evaluate the effects of cooling packing care on chemotherapy-induced skin toxicity reactions in cancer patients receiving chemotherapy. A systematic review approach was used. Searches were conducted in databases including Cochrane Library, Embase, MEDLINE, PubMed and Airiti Library using the keywords "chemotherapy cutaneous toxicity", "chemotherapy skin reaction", "chemotherapy skin toxicity", "frozen glove", "frozen sock", "cooling packaging care", "ice gloves", "ice socks", "usual care", "severity", "comfort", "satisfaction", "severity", and "comfort". The search focused on articles published before December 2016. Based on the inclusion and exclusion criteria, 5 articles involving relevant randomized controlled trials were extracted for review. Elasto-Gel ice gloves or ice socks that were chilled to -25°C- -30°C and used for 15 mins during initial chemotherapy, for one hour during chemotherapy infusion, and for 15 mins after chemotherapy were shown to improve the frequency and severity of chemotherapy-induced skin toxicity reactions. Several studies were limited by small sample sizes and different types of cooling packing programs, temperature, timing, and frequency. Thus, further research is recommended to verify the effects of cooling packing care. Cancer patients who were treated with docetaxel or PLD and who used ice gloves or ice socks that were chilled to -25°C- -30°C for 15 mins during initial chemotherapy, for one hour during chemotherapy infusion, and for 15 mins after chemotherapy improved significantly in terms of the frequency and severity of their chemotherapy-induced skin toxicity reactions. Local cooling packing care is a non-pharmacotherapy approach that is low cost and free of side effects. This review is intended to provide a reference for clinical care.

Vibrations of bioionic liquids by ab initio molecular dynamics and vibrational spectroscopy.

Science.gov (United States)

Tanzi, Luana; Benassi, Paola; Nardone, Michele; Ramondo, Fabio

2014-12-26

Density functional theory and vibrational spectroscopy are used to investigate a class of bioionic liquids consisting of a choline cation and carboxylate anions. Through quantum mechanical studies of motionless ion pairs and molecular dynamics of small portions of the liquid, we have characterized important structural features of the ionic liquid. Hydrogen bonding produces stable ion pairs in the liquid and induces vibrational features of the carboxylate groups comparable with experimental results. Infrared and Raman spectra of liquids have been measured, and main bands have been assigned on the basis of theoretical spectra.

Comprehensive vibration assessment program for Yonggwang nuclear power plant unit 4

International Nuclear Information System (INIS)

Rhee, Hui Nam; Hwang, Jong Keun; Kim, Tae Hyung; Kim, Jung Kyu; Song, Heuy Gap; Kim, Beom Shig

1995-01-01

A Comprehensive Vibration Assessment Program (CVAP) has been performed for Yonggwang Nuclear Power Plant Unit 4 (YGN 4) in order to verify the structural integrity of the reactor internals for flow induced vibrations prior to commercial operation. The theoretical evidence for the structural integrity of the reactor internals and the basis for measurement and inspection are provided by the analysis. Flow induced hydraulic loads and reactor internals vibration response data were measured during pre-core hot functional testing in YGN 4 site. Also, the critical areas in the reactor internals were inspected visually to check any existence of structural abnormality before and after the pre-core hot functional testing. Then, the measured data have been analyzed and compared with the predicted data by analysis. The measured stresses are less than the predicted values and the allowable limits. It is concluded that the vibration response of the reactor internals due to the flow induced vibration under normal operation is acceptable for long term operation

Hand-Arm vibration assessment among tiller operator

Directory of Open Access Journals (Sweden)

P. Nassiri

2013-08-01

Result: Results of the present study indicated that in all measured situations, exposure to hand arm vibration was higher than the standard limit suggested by Iranian occupational health committee and there was risk of vibration-induced disorders. The maximum exposure to vibration is in plowing ground. Exposure to hand arm vibration in three modes of plowing, transmission and natural, were respectively 16.95, 14.16 and 8.65 meters per second squared. Additionally, in all situations, vibration exposure was highest in the X-axis in comparison with Z- and Y-axes. .Conclusion: This study emphasizes on the need to provide intervention and controlling and managing strategies in order to eliminate or reduce vibration transmitted from tiller to operators hand and arm and also prevent to serious problems including neurovascular disorders, discomfort and white finger syndrome. Meanwhile, more studies are necessary to identify the sources of vibration on different models of tiller.

Numerical simulation of an elementary Vortex-Induced-Vibration problem by using fully-coupled fluid solid system computation

Directory of Open Access Journals (Sweden)

M Pomarède

2016-09-01

Full Text Available Numerical simulation of Vortex-Induced-Vibrations (VIV of a rigid circular elastically-mounted cylinder submitted to a fluid cross-flow has been extensively studied over the past decades, both experimentally and numerically, because of its theoretical and practical interest for understanding Flow-Induced-Vibrations (FIV problems. In this context, the present article aims to expose a numerical study based on fully-coupled fluid-solid computations compared to previously published work [34], [36]. The computational procedure relies on a partitioned method ensuring the coupling between fluid and structure solvers. The fluid solver involves a moving mesh formulation for simulation of the fluid structure interface motion. Energy exchanges between fluid and solid models are ensured through convenient numerical schemes. The present study is devoted to a low Reynolds number configuration. Cylinder motion magnitude, hydrodynamic forces, oscillation frequency and fluid vortex shedding modes are investigated and the “lock-in” phenomenon is reproduced numerically. These numerical results are proposed for code validation purposes before investigating larger industrial applications such as configurations involving tube arrays under cross-flows [4].

One stacked-column vibration test and analysis for VHTR core

International Nuclear Information System (INIS)

Ikushima, Takeshi; Ishizuka, Hiroshi; Ide, Akira; Hayakawa, Hitoshi; Shingai, Kazuteru.

1978-07-01

This paper describes experimental results of the vibration test on a single stacked-column and compares them with the analytical results. A 1/2 scale model of the core element of a very high temperature gas-cooled reactor (VHTR) was set on a shaking table. Sinusoidal waves, response time history waves, beat wave and step wave of input acceleration 100 - 900 gal in the frequency of 0.5 to 15 Hz were used to vibrate the table horizontally. Results are as follows: (1) The column has a non-linear resonance and exhibits a hysteresis response with jump points. (2) The column vibration characteristics is similar to that of the finite beams connected with non-linear soft spring. (3) The column resonance frequency decreases with increasing input acceleration. (4) The impact force increases with increasing input acceleration and boundary gap width. (5) Good correlation in vibration behavior of the stacked-column and impact force on the boundary between test and analysis was obtained. (auth.)

Suppressing molecular vibrations in organic semiconductors by inducing strain.

Science.gov (United States)

Kubo, Takayoshi; Häusermann, Roger; Tsurumi, Junto; Soeda, Junshi; Okada, Yugo; Yamashita, Yu; Akamatsu, Norihisa; Shishido, Atsushi; Mitsui, Chikahiko; Okamoto, Toshihiro; Yanagisawa, Susumu; Matsui, Hiroyuki; Takeya, Jun

2016-04-04

Organic molecular semiconductors are solution processable, enabling the growth of large-area single-crystal semiconductors. Improving the performance of organic semiconductor devices by increasing the charge mobility is an ongoing quest, which calls for novel molecular and material design, and improved processing conditions. Here we show a method to increase the charge mobility in organic single-crystal field-effect transistors, by taking advantage of the inherent softness of organic semiconductors. We compress the crystal lattice uniaxially by bending the flexible devices, leading to an improved charge transport. The mobility increases from 9.7 to 16.5 cm(2) V(-1) s(-1) by 70% under 3% strain. In-depth analysis indicates that compressing the crystal structure directly restricts the vibration of the molecules, thus suppresses dynamic disorder, a unique mechanism in organic semiconductors. Since strain can be easily induced during the fabrication process, we expect our method to be exploited to build high-performance organic devices.

Cooling system upgrading from 250 kW to 1 MW

International Nuclear Information System (INIS)

Anderson, T.V.; Johnson, A.G.; Ringle, J.C.

1972-01-01

The Oregon State TRIGA reactor (OSTR) power capability was upgraded from 250 KW to 1 MW in 1969; however, funds were not available for simultaneous upgrading of the cooling system. Since then, the OSTR has been selectively operating at full power with the original 250 KW cooling system. After funds were made available in 1971 the construction on the new heat exchanger building began. The new cooling system was installed, equipment was checked out, corrections were made, and acceptance tests were run. In addition, several days were required to clean up the primary system water, since increased water flow (350 gpm) swirled 4 year's collection of sediment off the reactor tank bottom and into the primary system. Three interesting items have been noticed, which are apparently a result of the cooling system upgrading: (1) the radiation levels above the reactor tank have been reduced by a factor of 2 to 3, (2) a low resonance vibration in the reactor core occurs at 1 MW. The vibration is attributed to a combination of increased water turbulence and subcooled (surface) nucleate boiling, and (3) direct radiation levels from the demineralizer tank have increased approximately 8-fold. This resulted in a relocation of the tank and the use of supplemental shielding. Increased operating time at higher average power levels, plus disturbance of; sediment on the bottom of the reactor tank are believed to be the main sources of the higher radiation levels

Collaboratively Adaptive Vibration Sensing System for High-fidelity Monitoring of Structural Responses Induced by Pedestrians

Directory of Open Access Journals (Sweden)

Shijia Pan

2017-05-01

Full Text Available This paper presents a collaboratively adaptive vibration monitoring system that captures high-fidelity structural vibration signals induced by pedestrians. These signals can be used for various human activities’ monitoring by inferring information about the impact sources, such as pedestrian footsteps, door opening and closing, and dragging objects. Such applications often require high-fidelity (high resolution and low distortion signals. Traditionally, expensive high resolution and high dynamic range sensors are adopted to ensure sufficient resolution. However, for sensing systems that use low-cost sensing devices, the resolution and dynamic range are often limited; hence this type of sensing methods is not well explored ubiquitously. We propose a low-cost sensing system that utilizes (1 a heuristic model of the investigating excitations and (2 shared information through networked devices to adapt hardware configurations and obtain high-fidelity structural vibration signals. To further explain the system, we use indoor pedestrian footstep sensing through ambient structural vibration as an example to demonstrate the system performance. We evaluate the application with three metrics that measure the signal quality from different aspects: the sufficient resolution rate to present signal resolution improvement without clipping, the clipping rate to measure the distortion of the footstep signal, and the signal magnitude to quantify the detailed resolution of the detected footstep signal. In experiments conducted in a school building, our system demonstrated up to 2× increase on the sufficient resolution rate and 2× less error rate when used to locate the pedestrians as they walk along the hallway, compared to a fixed sensing setting.

Flow-induced vibration analysis of a helical coil steam generator experiment using large eddy simulation

Energy Technology Data Exchange (ETDEWEB)

Yuan, Haomin; Solberg, Jerome; Merzari, Elia; Kraus, Adam; Grindeanu, Iulian

2017-10-01

This paper describes a numerical study of flow-induced vibration in a helical coil steam generator experiment conducted at Argonne National Laboratory in the 1980s. In the experiment, a half-scale sector model of a steam generator helical coil tube bank was subjected to still and flowing air and water, and the vibrational characteristics were recorded. The research detailed in this document utilizes the multi-physics simulation toolkit SHARP developed at Argonne National Laboratory, in cooperation with Lawrence Livermore National Laboratory, to simulate the experiment. SHARP uses the spectral element code Nek5000 for fluid dynamics analysis and the finite element code DIABLO for structural analysis. The flow around the coil tubes is modeled in Nek5000 by using a large eddy simulation turbulence model. Transient pressure data on the tube surfaces is sampled and transferred to DIABLO for the structural simulation. The structural response is simulated in DIABLO via an implicit time-marching algorithm and a combination of continuum elements and structural shells. Tube vibration data (acceleration and frequency) are sampled and compared with the experimental data. Currently, only one-way coupling is used, which means that pressure loads from the fluid simulation are transferred to the structural simulation but the resulting structural displacements are not fed back to the fluid simulation

Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

Energy Technology Data Exchange (ETDEWEB)

Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

2009-05-07

Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, Californial 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

2015-05-07

Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.

Influence of contact conditions on vibration induced wear of metals

International Nuclear Information System (INIS)

Hofmann, P.J.; Schettler, T.; Wieling, N.; Steininger, D.A.

1990-01-01

Unfavourable design characteristics of nuclear power plant steam generators and heat exchangers in general may result in vibration induced tube wear. A systematic investigation was performed on the contact conditions which may appear between heat exchanger tubes and tube support structure and the influence of different parameters e.g., normal contact force, on the resulting steady state wear rates. It is concluded that not only are contact forces and sliding distances important in the wear process but also the type of relative motion has a decisive influence on the resulting wear rates. For a certain 'work rate', the wear rate caused by repeated impact motions between tube and tube support structure may be an order of magnitude higher than that caused by only sliding motion. This is the result of different operating wear mechanisms which are discussed in this paper. (orig.)

Toward Cooling Uniformity: Investigation of Spiral, Sweeping Holes, and Unconventional Cooling Paradigms

Science.gov (United States)

Shyam, Vikram; Thurman, Douglas R.; Poinsatte, Philip E.; Ameri, Ali A.; Culley, Dennis E.

2018-01-01

Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. Ways to quantify the efficacy of novel cooling holes that are asymmetric, not uniformly spaced or that show variation from hole to hole are presented. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and square holes. A patent-pending spiral hole design showed the highest potential of the nondiffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing ratios of 1.0, 1.5, 2.0, and 2.5 at a density ratio of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS. A section on ideas for future work is included that addresses issues of quantifying cooling uniformity and provides some ideas for changing the way we think about cooling such as changing the direction of cooling or coupling acoustic devices to cooling holes to regulate frequency.

Predictive analyses of flow-induced vibration and fretting wear in steam generator tubes

International Nuclear Information System (INIS)

Axisa, F.

1989-01-01

Maintaining the service life of PWR steam generators under highly reliable conditions requires a complex design to prevent various damaging processes, including those related to flow induced vibration. Predictive analyses have to rely on numerical tools to compute the vibratory response of multi-supported tubes in association with experimental data and semi-empirical relationships for quantifying flow-induced excitation mechanisms and tube damaging processes. In the presence of loose supports tube dynamics becomes highly nonlinear in nature. To deal with such problems CEA and FRAMATOME developed a computer program called GERBOISE. This paper provides a short description of an experimental program currently in progress at CEN Saclay to validate the numerical methods implemented in GERBOISE. According to the results obtained so far reasonable agreement is obtained between experiment and numerical simulation, especially as averaged quantities are concerned

Vibration-induced particle formation during yogurt fermentation-Effect of frequency and amplitude.

Science.gov (United States)

Körzendörfer, Adrian; Temme, Philipp; Schlücker, Eberhard; Hinrichs, Jörg; Nöbel, Stefan

2018-05-01

Machinery such as pumps used for the commercial production of fermented milk products cause vibrations that can spread to the fermentation tanks. During fermentation, such vibrations can disturb the gelation of milk proteins by causing texture defects including lumpiness and syneresis. To study the effect of vibrations on yogurt structure systematically, an experimental setup was developed consisting of a vibration exciter to generate defined vibrational states and accelerometers for monitoring. During the fermentation of skim milk, vibrations (frequency sweep: 25 to 1,005 Hz) were introduced at different pH (5.7 to 5.1, step width 0.1 units) for 200 s. Physical properties of set gels (syneresis, firmness) and resultant stirred yogurts (visible particles, rheology, laser diffraction) were analyzed. Vibrational treatments at pH 5.5 to 5.2 increased syneresis, gel firmness, and the number of large particles (d > 0.9 mm); hence, this period was considered critical. The particle number increased from 34 ± 5 to 242 ± 16 particles per 100 g of yogurt due to vibrations at pH 5.4. In further experiments, yogurts were excited with fixed frequencies (30, 300, and 1,000 Hz). All treatments increased syneresis, firmness, and particle formation. As the strongest effect was observed by applying 30 Hz, the amplitude was set to vibration accelerations of a = 5, 10, 15, 20, and 25 m/s 2 in the final experiments. The number of large particles was increased due to each treatment and a positive correlation with the amplitude was found. We concluded that vibrations during gelation increase the collision probability of aggregating milk proteins, resulting in a compressed set gel with syneresis. Resultant stirred yogurts exhibit large particles with a compact structure leading to a reduced water-holding capacity and product viscosity. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

An Intelligent Optimization Method for Vortex-Induced Vibration Reducing and Performance Improving in a Large Francis Turbine

Directory of Open Access Journals (Sweden)

Xuanlin Peng

2017-11-01

Full Text Available In this paper, a new methodology is proposed to reduce the vortex-induced vibration (VIV and improve the performance of the stay vane in a 200-MW Francis turbine. The process can be divided into two parts. Firstly, a diagnosis method for stay vane vibration based on field experiments and a finite element method (FEM is presented. It is found that the resonance between the Kármán vortex and the stay vane is the main cause for the undesired vibration. Then, we focus on establishing an intelligent optimization model of the stay vane’s trailing edge profile. To this end, an approach combining factorial experiments, extreme learning machine (ELM and particle swarm optimization (PSO is implemented. Three kinds of improved profiles of the stay vane are proposed and compared. Finally, the profile with a Donaldson trailing edge is adopted as the best solution for the stay vane, and verifications such as computational fluid dynamics (CFD simulations, structural analysis and fatigue analysis are performed to validate the optimized geometry.

Amplitude control of the track-induced self-excited vibration for a maglev system.

Science.gov (United States)

Zhou, Danfeng; Li, Jie; Zhang, Kun

2014-09-01

The Electromagnet Suspension (EMS) maglev train uses controlled electromagnetic forces to achieve suspension, and self-excited vibration may occur due to the flexibility of the track. In this article, the harmonic balance method is applied to investigate the amplitude of the self-excited vibration, and it is found that the amplitude of the vibration depends on the voltage of the power supplier. Based on this observation, a vibration amplitude control method, which controls the amplitude of the vibration by adjusting the voltage of the power supplier, is proposed to attenuate the vibration. A PI controller is designed to control the amplitude of the vibration at a given level. The effectiveness of this method shows a good prospect for its application to commercial maglev systems. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Hearing with an atympanic ear: good vibration and poor sound-pressure detection in the royal python, Python regius

DEFF Research Database (Denmark)

Christensen, Christian Bech; Christensen-Dalsgaard, Jakob; Brandt, Christian

2012-01-01

are sensitive to sound pressure and (2) snakes are sensitive to vibrations, but cannot hear the sound pressure per se. Vibration and sound-pressure sensitivities were quantified by measuring brainstem evoked potentials in 11 royal pythons, Python regius. Vibrograms and audiograms showed greatest sensitivity...... at low frequencies of 80-160 Hz, with sensitivities of -54 dB re. 1 m s(-2) and 78 dB re. 20 μPa, respectively. To investigate whether pythons detect sound pressure or sound-induced head vibrations, we measured the sound-induced head vibrations in three dimensions when snakes were exposed to sound...... pressure at threshold levels. In general, head vibrations induced by threshold-level sound pressure were equal to or greater than those induced by threshold-level vibrations, and therefore sound-pressure sensitivity can be explained by sound-induced head vibration. From this we conclude that pythons...

Improvement of Cooling Technology through Atmosphere Gas Management

Energy Technology Data Exchange (ETDEWEB)

Renard, Michel; Dosogne, Edgaar; Crutzen, Jean Pierre; Raick, Jean Mare [DREVER INTERNATIONAL S.A., Liege (Belgium); Ji, Ma Jia; Jun, Lv; Zhi, Ma Bing [SHOUGANG Cold Rolling Mill Headquarter, Beijin (China)

2009-12-15

The production of advanced high strength steels requires the improvement of cooling technology. The use of high cooling rates allows relatively low levels of expensive alloying additions to ensure sufficient hardenability. In classical annealing and hot-dip galvanizing lines a mixing station is used to provide atmosphere gas containing 3-5% hydrogen and 97-95% nitrogen in the various sections of the furnace, including the rapid cooling section. Heat exchange enhancement in this cooling section can be insured by the increased hydrogen concentration. Driver international developed a patented improvement of cooling technology based on the following features: pure hydrogen gas is injected only in the rapid cooling section whereas the different sections of the furnace are supplied with pure nitrogen gas: the control of flows through atmosphere gas management allows to get high hydrogen concentration in cooling section and low hydrogen content in the other furnace zones. This cooling technology development insures higher cooling rates without additional expensive hydrogen gas consumption and without the use of complex sealing equipment between zones. In addition reduction in electrical energy consumption is obtained. This atmosphere control development can be combined with geometrical design improvements in order to get optimised cooling technology providing high cooling rates as well as reduced strip vibration amplitudes. Extensive validation of theoretical research has been conducted on industrial lines. New lines as well as existing lines, with limited modifications, can be equipped with this new development. Up to now this technology has successfully been implemented on 6 existing and 7 new lines in Europe and Asia.

Cause elucidation of sodium leakage incident at `Monju` reactor. Vibration of thermometer due to fluid force

Energy Technology Data Exchange (ETDEWEB)

Iwata, Koji; Wada, Yusaku; Morishita, Masaki; Yamaguchi, Akira; Ichimiya, Masakazu [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1997-01-01

This is a report of summarized results of investigation and analysis on fracture of thermometer which is direct reason of sodium leakage incident at the second main cooling system of fast breeder reactor `Monju`. Various surveys such as on various damage factors, on flowing power vibrational features containing flowing power vibrational test of thermometer, on evaluation of high cycle fatigue due to flowing power vibration and details on propagation of and fracture due to fatigue crack, on why only said thermometer damaged, and so forth were executed. As results of these examinations, a decision was arrived that high cycle fatigue due to vibration formed by fluid force (fluid force vibration) was a direct cause of the thermometer damage. (G.K.)

Compact, single-tube scanning tunneling microscope with thermoelectric cooling.

Science.gov (United States)

Jobbins, Matthew M; Agostino, Christopher J; Michel, Jolai D; Gans, Ashley R; Kandel, S Alex

2013-10-01

We have designed and built a scanning tunneling microscope with a compact inertial-approach mechanism that fits inside the piezoelectric scanner tube. Rigid construction allows the microscope to be operated without the use of external vibration isolators or acoustic enclosures. Thermoelectric cooling and a water-ice bath are used to increase temperature stability when scanning under ambient conditions.

Exact analytical solution of shear-induced flexural vibration of functionally graded piezoelectric beam

Energy Technology Data Exchange (ETDEWEB)

Sharma, Pankaj, E-mail: psharma@rtu.ac.in; Parashar, Sandeep Kumar, E-mail: parashar2@yahoo.com [Mechanical Engineering Department, Rajasthan Technical University, Kota (India)

2016-05-06

The priority of this paper is to obtain the exact analytical solution for free flexural vibration of FGPM beam actuated using the d{sub 15} effect. In piezoelectric actuators, the potential use of d{sub 15} effect has been of particular interest for engineering applications since shear piezoelectric coefficient d15 is much higher than the other piezoelectric coupling constants d{sub 31} and d{sub 33}. The applications of shear actuators are to induce and control the flexural vibrations of beams and plates. In this study, a modified Timoshenko beam theory is used where electric potential is assumed to vary sinusoidaly along the thickness direction. The material properties are assumed to be graded across the thickness in accordance with power law distribution. Hamilton's principle is employed to obtain the equations of motion along with the associated boundary conditions for FGPM beams. Exact analytical solution is derived thus obtained equations of motion. Results for clamped-clamped and clamped-free boundary conditions are presented. The presented result and method shell serve as benchmark for comparing the results obtained from the other approximate methods.

A Peltier cooling diamond anvil cell for low-temperature Raman spectroscopic measurements

Science.gov (United States)

Noguchi, Naoki; Okuchi, Takuo

2016-12-01

A new cooling system using Peltier modules is presented for a low-temperature diamond anvil cell instrument. This cooling system has many advantages: it is vibration-free, low-cost, and compact. It consists of double-stacked Peltier modules and heat sinks, where a cooled ethylene glycol-water mixture flows through a chiller. Current is applied to the Peltier modules by two programmable DC power supplies. Sample temperature can be controlled within the range 210-300 K with a precision of ±0.1 K via a Proportional-Integral-Differential (PID) control loop. A Raman spectroscopic study for the H2O ice VII-VIII transition is shown as an example of an application of the Peltier cooling diamond anvil cell system.

Reactor internals vibration monitoring by neutron noise methods in PWRs

International Nuclear Information System (INIS)

Pazsit, I.; Por, G.; Lux, I.

1983-01-01

Certain elements of PWR cores such as control/fuel rods or cassettes, or other parts of reactor internals, often represent a vibration problem. Early analyses at operating PWR plant revealed that these vibrations can be detected by in-core neutron detectors, opening up the possibility of vibration monitoring and diagnostics by noise methods. Theoretical methods of calculating vibration induced neutron noise and its application to vibration diagnostics are summarized. Experiments to check theoretical conclusions are under way at the Central Research Institute for Physics, Budapest. (author)

Identification of warm day and cool night conditions induced flowering-related genes in a Phalaenopsis orchid hybrid by suppression subtractive hybridization.

Science.gov (United States)

Li, D M; Lü, F B; Zhu, G F; Sun, Y B; Xu, Y C; Jiang, M D; Liu, J W; Wang, Z

2014-02-14

The influence of warm day and cool night conditions on induction of spikes in Phalaenopsis orchids has been studied with respect to photosynthetic efficiency, metabolic cycles and physiology. However, molecular events involved in spike emergence induced by warm day and cool night conditions are not clearly understood. We examined gene expression induced by warm day and cool night conditions in the Phalaenopsis hybrid Fortune Saltzman through suppression subtractive hybridization, which allowed identification of flowering-related genes in warm day and cool night conditions in spikes and leaves at vegetative phase grown under warm daily temperatures. In total, 450 presumably regulated expressed sequence tags (ESTs) were identified and classified into functional categories, including metabolism, development, transcription factor, signal transduction, transportation, cell defense, and stress. Furthermore, database comparisons revealed a notable number of Phalaenopsis hybrid Fortune Saltzman ESTs that matched genes with unknown function. The expression profiles of 24 genes (from different functional categories) have been confirmed by quantitative real-time PCR in induced spikes and juvenile apical leaves. The results of the real-time PCR showed that, compared to the vegetative apical leaves, the transcripts of genes encoding flowering locus T, AP1, AP2, KNOX1, knotted1-like homeobox protein, R2R3-like MYB, adenosine kinase 2, S-adenosylmethionine synthetase, dihydroflavonol 4-reductase, and naringenin 3-dioxygenase accumulated significantly higher levels, and genes encoding FCA, retrotransposon protein Ty3 and C3HC4-type RING finger protein accumulated remarkably lower levels in spikes of early developmental stages. These results suggested that the genes of two expression changing trends may play positive and negative roles in the early floral transition of Phalaenopsis orchids. In conclusion, spikes induced by warm day and cool night conditions were complex in

Feasibility and safety of inducing modest hypothermia in awake patients with acute stroke through surface cooling

DEFF Research Database (Denmark)

Kammersgaard, L P; Rasmussen, B H; Jørgensen, Henrik Stig

2000-01-01

Hypothermia reduces neuronal damage in animal stroke models. Whether hypothermia is neuroprotective in patients with acute stroke remains to be clarified. In this case-control study, we evaluated the feasibility and safety of inducing modest hypothermia by a surface cooling method in awake patients...

Development and modelisation of a hydro-power conversion system based on vortex induced vibration

Science.gov (United States)

Lefebure, David; Dellinger, Nicolas; François, Pierre; Mosé, Robert

2016-11-01

The Vortex Induced Vibration (VIV) phenomenon leads to mechanical issues concerning bluff bodies immerged in fluid flows and have therefore been studied by numerous authors. Moreover, an increasing demand for energy implies the development of alternative, complementary and renewable energy solutions. The main idea of EauVIV project consists in the use of VIV rather than its deletion. When rounded objects are immerged in a fluid flow, vortices are formed and shed on their downstream side, creating a pressure imbalance resulting in an oscillatory lift. A convertor modulus consists of an elastically mounted, rigid cylinder on end-springs, undergoing flow- induced motion when exposed to transverse fluid-flow. These vortices induce cyclic lift forces in opposite directions on the circular bar and cause the cylinder to vibrate up and down. An experimental prototype was developed and tested in a free-surface water channel and is already able to recover energy from free-stream velocity between 0.5 and 1 m.s -1. However, the large number of parameters (stiffness, damping coefficient, velocity of fluid flow, etc.) associated with its performances requires optimization and we choose to develop a complete tridimensionnal numerical model solution. A 3D numerical model has been developed in order to represent the real system behavior and improve it through, for example, the addition of parallel cylinders. The numerical model build up was carried out in three phases. The first phase consists in establishing a 2D model to choose the turbulence model and quantify the dependence of the oscillations amplitudes on the mesh size. The second corresponds to a 3D simulation with cylinder at rest in first time and with vertical oscillation in a second time. The third and final phase consists in a comparison between the experimental system dynamic behavior and its numerical model.

Simulation Study on Train-Induced Vibration Control of a Long-Span Steel Truss Girder Bridge by Tuned Mass Dampers

Directory of Open Access Journals (Sweden)

Hao Wang

2014-01-01

Full Text Available Train-induced vibration of steel truss bridges is one of the key issues in bridge engineering. This paper talks about the application of tuned mass damper (TMD on the vibration control of a steel truss bridge subjected to dynamic train loads. The Nanjing Yangtze River Bridge (NYRB is taken as the research object and a recorded typical train load is included in this study. With dynamic finite element (FE method, the real-time dynamic responses of NYRB are analyzed based on a simplified train-bridge time-varying system. Thereinto, two cases including single train moving at one side and two trains moving oppositely are specifically investigated. According to the dynamic characteristics and dynamic responses of NYRB, the fourth vertical bending mode is selected as the control target and the parameter sensitivity analysis on vibration control efficiency with TMD is conducted. Using the first-order optimization method, the optimal parameters of TMD are then acquired with the control efficiency of TMD, the static displacement of Midspan, expenditure of TMDs, and manufacture difficulty of the damper considered. Results obtained in this study can provide references for the vibration control of steel truss bridges.

Frequency adjustable MEMS vibration energy harvester

Science.gov (United States)

Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

2016-10-01

Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

Frequency adjustable MEMS vibration energy harvester

International Nuclear Information System (INIS)

Podder, P; Constantinou, P; Roy, S; Amann, A

2016-01-01

Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators. (paper)

Combined experimental and numerical investigation of energy harness utilizing vortex induced vibration over half cylinder using piezoelectric beams

Science.gov (United States)

Ahmed, Md. Tusher; Hossain, Md. Tanver; Rahman, Md. Ashiqur

2017-06-01

Energy harvesting technology has the ability to create self-powered electronic systems that do not rely on battery power for their operation. Wind energy can be converted into electricity via a piezoelectric transducer during the air flow over a cylinder. The vortex-induced vibration over the cylinder causes the piezoelectric beam to vibrate. Thus useful electric energy at the range 0.2-0.3V is found which can be useful for self-powering small electronic devices. In the present study, prototypes of micro-energy harvester with a shape of 65 mm × 37 mm × 0.4 mm are developed and tested for airflow over D-shaped bluff body for diameters of 15, 20 and 28mm in an experimental setup consisting of a long wind tunnel of 57cm × 57cm with variable speeds of the motor for different flow velocities and the experimental setup is connected at the downstream where flow velocity is the maximum. Experimental results show that the velocity and induced voltage follows a regular linear pattern. A maximum electrical potential of 140 mV for velocity of 1.1 ms-1 at a bluff body diameter of 15 mm is observed in the energy harvester that can be applied in many practical cases for self-powering electronic devices. The simulation of this energy harvesting phenomena is then simulated using COMSOLE multi-physics. Diameter of the bluff bodies as well as flow velocity and size of cantilever beam are varied and the experimental findings are found to be in good agreement with the simulated ones. The simulations along with the experimental data show the possibility of generating electricity from vortex induced vibration and can be applied in many practical cases for self-powering electronic devices.

Fluid elastic vibration of nuclear fuel assemblies

International Nuclear Information System (INIS)

Kim, S. N.; Jung, S. Y.

1998-01-01

Since utilities and fuel venders have adopted the fuel design of high burn-up and improved thermal margin flow mixing vane, several PWR nuclear power plants have in recent years experienced fretting wear fuel rod failure due to flow induced vibration. Flow induced vibration can be resulted from fluidelastic instability, periodic shedding, turbulence-induced excitation, and acoustic resonance (1). Among these mechanisms found in the core of nuclear power plant, the governing mechanism that is fluidelastic instability, could be inferred from the analysis of fuel failure patterns. Therefore, to simulate the fuel failure in nuclear power plants, Tanaka's model (2) was chosen as most suitable one, which is well explaining the damage pattern, in particular it's second row damage characteristics. In the model, unsteady fluid dynamic forces acting on the vibrating cyclinders were included which consists of the inertia forces due to the added mass of fluid, damping forces of fluid in phase to the cylinder vibrating velocity, and stiffness forces proportional to cylinder displacements. However, the model did not account for radiation effect-spring forces deflection. So, the model was modified to account for the spring force relaxation due to radiation exposure. The stiffness of spring was fitted with experimental data. Finally the critical velocities were calculated with the modified spring force at beginning and end of cycle

Piezoelectric Wind Energy Harvesting from Self-Excited Vibration of Square Cylinder

Directory of Open Access Journals (Sweden)

Junlei Wang

2016-01-01

Full Text Available Self-excited vibration of a square cylinder has been considered as an effective way in harvesting piezoelectric wind energy. In present work, both of the vortex-induced vibration and unstable galloping phenomenon process are investigated in a reduced velocity (Ur=U/ωn·D range of 4≤Ur≤20 with load resistance ranging in 100 Ω≤R≤1 MΩ. The vortex-induced vibration covers presynchronization, synchronization, and postsynchronization branches. An aeroelectromechanical model is given to describe the coupling of the dynamic equation of the fluid-structure interaction and the equation of Gauss law. The effects of load resistance are investigated in both the open-circuit and close-circuit system by a linear analysis, which covers the parameters of the transverse displacement, aerodynamic force, output voltage, and harvested power utilized to measure the efficiency of the system. The highest level of the transverse displacement and the maximum value of harvested power of synchronization branch during the vortex-induced vibration and galloping are obtained. The results show that the large-amplitude galloping at high wind speeds can generate energy. Additionally, energy can be harvested by utilization of the lock-in phenomenon of vortex-induced vibration under low wind speed.

Non-traditional vibration mitigation methods for reciprocating compressor system

NARCIS (Netherlands)

Eijk, A.; Lange, T.J. de; Vreugd, J. de; Slis, E.J.P.

2016-01-01

Reciprocating compressors generate vibrations caused by pulsation-induced forces, mechanical (unbalanced) free forces and moments, crosshead guide forces and cylinder stretch forces. The traditional way of mitigating the vibration and cyclic stress levels to avoid fatigue failure of parts of the

CFD simulation of flow-induced vibration of an elastically supported airfoil

Directory of Open Access Journals (Sweden)

Šidlof Petr

2016-01-01

Full Text Available Flow-induced vibration of lifting or control surfaces in aircraft may lead to catastrophic consequences. Under certain circumstances, the interaction between the airflow and the elastic structure may lead to instability with energy transferred from the airflow to the structure and with exponentially increasing amplitudes of the structure. In the current work, a CFD simulation of an elastically supported NACA0015 airfoil with two degrees of freedom (pitch and plunge coupled with 2D incompressible airflow is presented. The geometry of the airfoil, mass, moment of inertia, location of the centroid, linear and torsional stiffness was matched to properties of a physical airfoil model used for wind-tunnel measurements. The simulations were run within the OpenFOAM computational package. The results of the CFD simulations were compared with the experimental data.

Corrosion induced clogging and plugging in water-cooled generator cooling circuit

International Nuclear Information System (INIS)

Park, B.G.; Hwang, I.S.; Rhee, I.H.; Kim, K.T.; Chung, H.S.

2002-01-01

Water-cooled electrical generators have been experienced corrosion-related problems that are restriction of flow through water strainers caused by collection of excessive amounts of copper corrosion products (''clogging''), and restriction of flow through the copper strands in the stator bars caused by growth or deposition of corrosion products on the walls of the hollow strands (''plugging''). These phenomena result in unscheduled shutdowns that would be a major concern because of the associated loss in generating capacity. Water-cooled generators are operated in one of two modes. They are cooled either with aerated water (dissolved oxygen >2 ppm) or with deaerated water (dissolved oxygen <50 ppb). Both modes maintain corrosion rates at satisfactorily low levels as long as the correct oxygen concentrations are maintained. However, it is generally believed that very much higher copper corrosion rates result at the intermediate oxygen concentrations of 100-1000 ppb. Clogging and plugging are thought to be associated with these intermediate concentrations, and many operators have suggested that the period of change from high-to-low or from low-to-high oxygen concentration is particularly damaging. In order to understand the detailed mechanism(s) of the copper oxide formation, release and deposition and to identify susceptible conditions in the domain of operating variables, a large-scale experiments are conducted using six hollow strands of full length connected with physico-chemically scaled generator cooling water circuit. To ensure a close simulation of thermal-hydraulic conditions in a generator stator, strands of the loop will be ohmically heated using AC power supply. Experiments is conducted to cover oxygen excursions in both high dissolved oxygen and low dissolved oxygen conditions that correspond to two representative operating condition at fields. A thermal upset condition is also simulated to examine the impact of thermal stress. During experiments

Experimental evaluation of vibrations in heat exchangers

International Nuclear Information System (INIS)

Martin Ghiselli, A.

1997-01-01

Flow induced vibrations may produce damage of heat exchangers, condensers and steam generators tubes. To evaluate this problem a set of tests were developed to know the real support state of the tubes, which have great influence on the vibration response. This paper include a description of the tests and the results obtained applying them on a heat exchanger equipment. (author) [es

Vibration aging of diesel-engine mounted electrical equipment

International Nuclear Information System (INIS)

Lee, B.J.; Morton, W.C.

1994-01-01

The Emergency Diesel Generator (EDG) in a Nuclear Power Plant is considered to be a component which is essential to safe plant operation. Failures of auxiliary equipment directly mounted on the EDG creates costly repairs, and compromises the engine's availability and reliability. Although IEEE-323 requires addressing of safety-related components due to mechanically induced vibration, very few guidelines exist in the nuclear industry to show how this may be accounted for. Most engine vendors rely on the empirical experience data as the basis of their evaluation for vibration. Upgrade of engine controls, addition of monitoring devices and other engine modifications require design and installation of new equipment to be mounted directly on the engine. This necessitates the evaluation for engine-induced vibration which is considered to be one of the most severe design parameters. This paper discusses the engine vibration characteristics, and the acquisition of extensive field vibration data on the diesel engine under operating conditions. The data is then used to develop life cycle vibration qualification test profiles that can be applied with confidence in a laboratory environment to qualify engine-mounted equipment. The intent is to validate a product's ability to survive under worst case, extended service on-engine conditions. This paper describes the procedures and approaches used to achieve those goals, and provides developed profile examples and test results

On the physics of laser-induced selective photothermolysis of hair follicles: Influence of wavelength, pulse duration, and epidermal cooling.

Science.gov (United States)

Svaasand, Lars O; Nelson, J Stuart

2004-01-01

The physical basis for optimization of wavelength, pulse duration, and cooling for laser-induced selective photothermolysis of hair follicles in human skin is discussed. The results indicate that the most important optimization parameter is the cooling efficiency of the technique utilized for epidermal protection. The optical penetration is approximately the same for lasers at 694, 755, and 800 nm. The penetration of radiation from Nd:yttrium-aluminum-garnet lasers at 1064 nm is, however, somewhat larger. Photothermal damage to the follicle is shown to be almost independent of laser pulse duration up to 100 ms. The results reveal that epidermal cooling by a 30-80-ms-long cryogen spurt immediately before laser exposure is the only efficient technique for laser pulse durations less than 10 ms. For longer pulse durations in the 30-100 ms range, protection can be done efficiently by skin cooling during laser exposure. For laser pulses of 100 ms, an extended precooling period, e.g., by bringing a cold object into good thermal contact with the skin for about 1 s, can be of value. Thermal quenching of laser induced epidermal temperature rise after pulsed exposure can most efficiently be done with a 20 ms cryogen spurt applied immediately after irradiation. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

Flow-induced vibration for light-water reactors. Progress report, April 1978-December 1979

International Nuclear Information System (INIS)

Schardt, J.F.

1980-03-01

Flow-Induced vibration for Light Water Reactors (FIV for LWRs) is a four-year program designed to improve the FIV performance of light water reactors through the development of design criteria, analytical models for predicting behavior of components, general scaling laws to improve the accuracy of reduced-scale tests, and the identification of high FIV risk areas. The program commenced December 1, 1976, but was suspended on September 30, 1978, due to a shift in Department of Energy (DOE) priorities away from LWR productivity/availability. It was reinitiated as of August 1, 1979. This progress report summarizes the accomplishments achieved during the period from April 1978 to December 1979

Vortex dynamics in the wake of a pivoted cylinder undergoing vortex-induced vibrations with elliptic trajectories

Science.gov (United States)

Marble, Erik; Morton, Christopher; Yarusevych, Serhiy

2018-05-01

Vortex-induced vibrations of a pivoted cylinder are investigated experimentally at a fixed Reynolds number of 3100, a mass ratio of 10.8, and a range of reduced velocities, 4.42 ≤ U^* ≤ 9.05. For these conditions, the cylinder traces elliptic trajectories, with the experimental conditions producing three out of four possible combinations of orbiting direction and primary axis alignment relative to the incoming flow. The study focuses on the quantitative analysis of wake topology and its relation to this type of structural response. Velocity fields were measured using time-resolved, two-component particle image velocimetry (TR-PIV). These results show that phase-averaged wake topology generally agrees with the Morse and Williamson (J Fluids Struct 25(4):697-712, 2009) shedding map for one-degree-of-freedom vortex-induced vibrations, with 2S, 2{P}o, and 2P shedding patterns observed within the range of reduced velocities studied here. Vortex tracking and vortex strength quantification are used to analyze the vortex shedding process and how it relates to cylinder response. In the case of 2S vortex shedding, vortices are shed when the cylinder is approaching the maximum transverse displacement and reaches the streamwise equilibrium. 2P vortices are shed approximately half a period earlier in the cylinder's elliptic trajectory. Leading vortices shed immediately after the peak in transverse oscillation and trailing vortices shed near the equilibrium of transverse oscillation. The orientation and direction of the cylinder's elliptic trajectory are shown to influence the timing of vortex shedding, inducing changes in the 2P wake topology.

Good vibrations: Assessing the stability of snake venom composition after researcher-induced disturbance in the laboratory.

Science.gov (United States)

Claunch, Natalie M; Holding, Matthew L; Escallón, Camilo; Vernasco, Ben; Moore, Ignacio T; Taylor, Emily N

2017-07-01

Phenotypic plasticity contributes to intraspecific variation in traits of many animal species. Venom is an integral trait to the success and survival of many snake species, and potential plasticity in venom composition is important to account for in the context of basic research as well as in human medicine for treating the various symptoms of snakebite and producing effective anti-venoms. Researchers may unknowingly induce changes in venom variation by subjecting snakes to novel disturbances and potential stressors. We explored phenotypic plasticity in snake venom composition over time in captive Pacific rattlesnakes (Crotalus oreganus) exposed to vibration treatment, compared to an undisturbed control group. Venom composition did not change significantly in response to vibration, nor was there a detectable effect of overall time in captivity, even though snakes re-synthesized venom stores while subjected to novel disturbance in the laboratory. This result indicates that venom composition is a highly repeatable phenotype over short time spans and that the composition of venom within adult individuals may be resistant to or unaffected by researcher-induced disturbance. On the other hand, the change in venom composition, measured as movement along the first principle component of venom phenotype space, was associated with baseline corticosterone (CORT) levels in the snakes. While differential forms of researcher-induced disturbance may not affect venom composition, significant changes in baseline CORT, or chronic stress, may affect the venom phenotype, and further investigations will be necessary to assess the nature of the relationship between CORT and venom protein expression. Copyright © 2017 Elsevier Ltd. All rights reserved.

Feedback damping of a microcantilever at room temperature to the minimum vibration amplitude limited by the noise level.

Science.gov (United States)

Kawamura, Y; Kanegae, R

2016-06-17

Cooling the vibration amplitude of a microcantilever as low as possible is important to improve the sensitivity and resolutions of various types of scanning type microscopes and sensors making use of it. When the vibration amplitude is controlled to be smaller using a feed back control system, it is known that the obtainable minimum amplitude of the vibration is limited by the floor noise level of the detection system. In this study, we demonstrated that the amplitude of the thermal vibration of a microcantilever was suppressed to be about 0.15 pmHz(-1/2), which is the same value with the floor noise level, without the assistance of external cryogenic cooling. We think that one of the reason why we could reach the smaller amplitude at room temperature is due to stiffer spring constant of the lever, which leads to higher natural frequency and consequently lower floor noise level. The other reason is considered to be due to the increase in the laser power for the diagnostics, which lead to the decrease in the signal to noise ratio determined by the optical shot noise.

Modeling the interference of vortex-induced vibration and galloping for a slender rectangular prism

Science.gov (United States)

Mannini, Claudio; Massai, Tommaso; Marra, Antonino Maria

2018-04-01

Several bluff bodies in an airflow, such as rectangular cylinders with moderate side ratio, in particular conditions of mass and damping can experience the interference of vortex-induced vibration (VIV) and galloping. This promotes a combined instability, which one may call "unsteady galloping", with peculiar features and possibly large vibration amplitudes in flow speed ranges where no excitation is predicted by classical theories. The mathematical model proposed between the 70's and the 80's by Prof. Y. Tamura to simulate this phenomenon was considered here for the case study of a two-dimensional rectangular cylinder with a side ratio of 1.5, having the shorter section side perpendicular to the smooth airflow. This wake-oscillator model relies on the linear superposition of the unsteady wake force producing VIV excitation and the quasi-steady force that is responsible for galloping. The model formulation was slightly modified, and the way to determine a crucial parameter was changed, revealing a previously unexplored behavior of the equations. In the present form, the model is able to predict the dynamic response of the rectangular cylinder with a satisfactory qualitative and, to a certain extent, quantitative agreement with the experimental data, although the limitations of the present approach are clearly highlighted in the paper. The mathematical modeling of unsteady galloping and the analysis of the results offer a deep insight into this complicated phenomenon and its nonlinear features. The model also represents a useful engineering tool to estimate the vibration of a structure or structural element for which the interference of VIV and galloping is envisaged.

Motion of a drop driven by substrate vibrations

Science.gov (United States)

Brunet, P.; Eggers, J.; Deegan, R. D.

2009-01-01

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wet by the drop. Frequency of vibrations ranges from 30 to 200 Hz, and above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up/down symmetry-breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements.

The application of infrared synchrotron radiation to the study of interfacial vibrational modes

International Nuclear Information System (INIS)

Hirschmugl, C.J.; Williams, G.P.

1992-01-01

Synchrotron radiation provides an extremely bright broad-band source in the infrared which is ideally suited to the study of surface and interface vibrational modes in the range 50--3,000 cm -1 . Thus it covers the important range of molecule-substrate interactions, as well as overlapping with the more easily accessible near-ir region where molecular internal modes are found. Compared to standard broadband infrared sources such as globars, not only is it 1,000 times brighter, but its emittance matches the phase-space of the electrochemical cell leading to full utilization of this brightness advantage. In addition, the source is more stable even than water-cooled globars in vacuum for both short-term and long-term fluctuations. The authors summarize the properties of synchrotron radiation in the infrared, in particular pointing out the distinct differences between this and the x-ray region. They use experimental data in discussing important issues of signal to noise and address the unique problems and advantages of the synchrotron source. Thus they emphasize the important considerations necessary for developing new facilities. This analysis then leads to a discussion of phase-space matching to electrochemical cells, and to other surfaces in vacuum. Finally they show several examples of the application of infrared synchrotron radiation to surface vibrational spectroscopy. The examples are for metal crystal surfaces in ultra-high vacuum and include CO/Cu(100) and (111) and CO/K/Cu(100). The experiments show how the stability of the synchrotron source allows subtle changes in the background to be observed in addition to the discrete vibrational modes. These changes are due to electronic states induced by the adsorbate. In some cases the authors have seen interferences between these and the discrete vibrational modes, leading to a breakdown of the dipole selection rules, and the observation of additional modes

Nonlinear laser dynamics induced by frequency shifted optical feedback: application to vibration measurements.

Science.gov (United States)

Girardeau, Vadim; Goloni, Carolina; Jacquin, Olivier; Hugon, Olivier; Inglebert, Mehdi; Lacot, Eric

2016-12-01

In this article, we study the nonlinear dynamics of a laser subjected to frequency shifted optical reinjection coming back from a vibrating target. More specifically, we study the nonlinear dynamical coupling between the carrier and the vibration signal. The present work shows how the nonlinear amplification of the vibration spectrum is related to the strength of the carrier and how it must be compensated to obtain accurate (i.e., without bias) vibration measurements. The theoretical predictions, confirmed by numerical simulations, are in good agreement with the experimental data. The main motivation of this study is the understanding of the nonlinear response of a laser optical feedback imaging sensor for quantitative phase measurements of small vibrations in the case of strong optical feedback.

Vibrationally induced inversion of photoelectron forward-backward asymmetry in chiral molecule photoionization by circularly polarized light

Science.gov (United States)

Garcia, Gustavo A.; Nahon, Laurent; Daly, Steven; Powis, Ivan

2013-01-01

Electron–nuclei coupling accompanying excitation and relaxation processes is a fascinating phenomenon in molecular dynamics. A striking and unexpected example of such coupling is presented here in the context of photoelectron circular dichroism measurements on randomly oriented, chiral methyloxirane molecules, unaffected by any continuum resonance. Here, we report that the forward-backward asymmetry in the electron angular distribution, with respect to the photon axis, which is associated with photoelectron circular dichroism can surprisingly reverse direction according to the ion vibrational mode excited. This vibrational dependence represents a clear breakdown of the usual Franck–Condon assumption, ascribed to the enhanced sensitivity of photoelectron circular dichroism (compared with other observables like cross-sections or the conventional anisotropy parameter-β) to the scattering phase off the chiral molecular potential, inducing a dependence on the nuclear geometry sampled in the photoionization process. Important consequences for the interpretation of such dichroism measurements within analytical contexts are discussed. PMID:23828557

Flow-Induced Pulsation and Vibration in Hydroelectric Machinery Engineer’s Guidebook for Planning, Design and Troubleshooting

CERN Document Server

Dörfler, Peter; Coutu, André

2013-01-01

Since the 1970’s, an increasing amount of specialized research has focused on the problems created by instability of internal flow in hydroelectric power plants. However, progress in this field is hampered by the inter­disciplinary nature of the subject, between fluid mechanics, structural mechanics and hydraulic transients. Flow-induced Pulsation and Vibration in Hydroelectric Machinery provides a compact guidebook explaining the many different underlying physical mechanisms and their possible effects.   Typical phenomena are described to assist in the proper diagnosis of problems and various key strategies for solution are compared and considered with support from practical experience and real-life examples. The link between state-of the-art CFD computation and notorious practical problems is discussed  and quantitative data is provided on  normal levels of vibration and pulsation so realistic limits can be set for future projects. Current projects are also addressed as the possibilities and limitatio...

A study on the evaluation of vibration effect and the development of vibration reduction method for Wolsung unit 1 main steam piping

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyun; Kim, Yeon Whan [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Tae Ryong; Park, Jin Ho [Korea Atomic Energy Research Inst., Daeduk (Korea, Republic of)

1996-08-01

The main steam piping of nuclear power plant which runs between steam generator and high pressure turbine has been experienced to have a severe effect on the safe operation of the plant due to the vibration induced by the steam flowing inside the piping. The imposed cyclic loads by the vibration could result in the degradation of the related structures such as connection parts between main instruments, valves, pipe supports and building. The objective of the study is to reduce the vibration level of Wolsung nuclear power plant unit 1 main steam pipeline by analyzing vibration characteristics of the piping, identifying sources of the vibration and developing a vibration reduction method .The location of the maximum vibration is piping between the main steam header and steam chest .The stress level was found to be within the allowable limit .The main vibration frequency was found to be 4{approx}6 Hz which is the same as the natural frequency from model test .A vibration reduction method using pipe supports of energy absorbing type(WEAR)is selected .The measured vibration level after WEAR installation was reduced about 36{approx}77% in displacement unit (author). 36 refs., 188 figs.

International Conference on Acoustics and Vibration

CERN Document Server

Chaari, Fakher; Walha, Lasaad; Abdennadher, Moez; Abbes, Mohamed; Haddar, Mohamed

2017-01-01

The book provides readers with a snapshot of recent research and industrial trends in field of industrial acoustics and vibration. Each chapter, accepted after a rigorous peer-review process, reports on a selected, original piece of work presented and discussed at International Conference on Acoustics and Vibration (ICAV2016), which was organized by the Tunisian Association of Industrial Acoustics and Vibration (ATAVI) and held March 21-23, in Hammamet, Tunisia. The contributions, mainly written by north African authors, covers advances in both theory and practice in a variety of subfields, such as: smart materials and structures; fluid-structure interaction; structural acoustics as well as computational vibro-acoustics and numerical methods. Further topics include: engines control, noise identification, robust design, flow-induced vibration and many others.This book provides a valuable resource for both academics and professionals dealing with diverse issues in applied mechanics. By combining advanced theori...

Effect of supporting structure stiffness on the drive train assembly of an induced draft cooling tower under seismic effects

International Nuclear Information System (INIS)

Raghavan, N.; Ramasubramanian, S.; Khan, K.

2005-01-01

In a nuclear power project an induced draft cooling tower, as a safety-related structure and part of the main cooling system, has to perform satisfactorily under designated seismic effects. While the structural elements can be designed by conventional methods to ensure adequate safety, the seismic qualification of the mechanical components poses a challenge. The paper describes a methodology adopted for the seismic qualification of a typical Drive Train Assembly for the axial flow fan of an induced draft cooling tower, to ensure the structural integrity and functional operability of the assembly during Operating Base Earthquake and Safe Shutdown Earthquake conditions. This is achieved by performing a detailed finite element analysis of the rotating equipment assembly consisting of the electric motor, gear box and fan along with the drive shaft between the motor and the gear box. The various components are modeled using beam elements, plate elements and spring elements to idealize the flexible connections and supports. The floor response spectra derived from a dynamic analysis of the overall structure under stipulated seismic acceleration spectra are the main excitation inputs into the system. The results validate the adequacy of gaps for movement and the strengths of the couplings and bolts to withstand the applied loads. The assumed modeling and analysis methodology are seen to be acceptable procedures for seismic qualification of important components of the cooling tower. (authors)

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

Energy Technology Data Exchange (ETDEWEB)

Justino, Licínia L. G., E-mail: liciniaj@ci.uc.pt; Reva, Igor; Fausto, Rui [CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra (Portugal)

2016-07-07

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N{sub 2}, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

Science.gov (United States)

Justino, Licínia L. G.; Reva, Igor; Fausto, Rui

2016-07-01

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N2, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

International Nuclear Information System (INIS)

Justino, Licínia L. G.; Reva, Igor; Fausto, Rui

2016-01-01

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N 2 , Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

A THEORETICAL STUDY AND 3D MODELING OF NONLINEAR PASSIVE VIBRATION ISOLATOR

OpenAIRE

Sabyasachi Mukherjee

2017-01-01

The study of sound and vibration are closely related. Sound or "pressure waves" are generated by vibrating structures (e.g. vocal cords); these pressure waves can also induce the vibration of structures (e.g. ear drum). Hence, when trying to reduce noise it is often a problem in trying to reduce vibration. The high speed engines and machines when mounted on foundations and supports cause vibrations of excessive amplitude because of unbalance forces setup during their working. These are the di...

A case report of vibration-induced hand comorbidities in a postwoman

Directory of Open Access Journals (Sweden)

Violante Francesco S

2011-02-01

Full Text Available Abstract Background Prolonged exposure to hand-transmitted vibration is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and osteoarticular systems of the upper limbs. However, the available epidemiological evidence is derived from studies on high vibration levels caused by vibratory tools, whereas little is known about possible upper limb disorders caused by chronic exposure to low vibration levels emitted by fixed sources. Case presentation We present the case of a postwoman who delivered mail for 15 years using a low-powered motorcycle. The woman was in good health until 2002, when she was diagnosed with bilateral Raynaud's phenomenon. In March 2003 a bilateral carpal tunnel syndrome was electromyographically diagnosed; surgical treatment was ineffective. Further examinations in 2005 highlighted the presence of chronic tendonitis (right middle finger flexor. Risk assessment From 1987, for 15 years, our patient rode her motorcycle for 4 h/day, carrying a load of 20-30 kg. For about a quarter of the time she drove over country roads. Using the information collected about the tasks carried out every day by the postwoman and some measurements performed on both handles of the motorcycle, as well as on both iron parts of the handlebars, we reconstructed the woman's previous exposure to hand-arm vibration. 8-hour energy-equivalent frequency weighted acceleration was about 2.4 m/s2. The lifetime dose was 1.5 × 109(m2/s4hd. Conclusions The particular set of comorbidities presented by our patient suggests a common pathophysiological basis for all the diseases. Considering the level of exposure to vibrations and the lack of specific knowledge on the effects of vibration in women, we hypothesize an association between the work exposure and the onset of the diseases.

Utilization of noise analysis technique for mechanical vibrations estimation in the ATUCHA1 and Embalse Argentine NPP

International Nuclear Information System (INIS)

Lescano, V.H.; Wentzeis, L.M.; Guevara, M.; Moreno, C.; Pineyro, J.

1996-01-01

In Argentine, comprehensive noise measurements have been performed with the reactor instrumentation of the PHWR power plant Atucha I and Embalse. The Embalse reactor is a CANDU-600 (600 Mwe) type pressurized heavy water reactor. It's a heavy water moderator and heavy water cooled natural uranium fueled pressure tube system. Signal of vanadium and platinum type in core-self power neutron detectors of ex-core ion chambers and of a moderator pressure sensor have been recorded and analysed. The vibration of reactor internals as vertical and horizontal in-core neutron flux detectors units and the coolant channels systems, consisting of calandria and pressure tubes with fuel bundles, have been identified and monitored during normal reactor operation. Atucha I, is a PHWR reactor natural uranium fueled, and heavy water moderated and cooled. Neutron noise techniques using of ex-core ionization chambers and in-core Vanadium SPND's were implemented, among others, in order to produce early detection of anomalous vibrations in the reactor internals. Noise analysis was successfully performed to identify normal and peculiar vibrations in particular reactor internals. (author)

Vibration of helical springs in cross water flow