Active twist control methodology for vibration reduction of a helicopter with dissimilar rotor system

International Nuclear Information System (INIS)

Pawar, Prashant M; Jung, Sung Nam

2009-01-01

In this work, an active vibration reduction of hingeless composite rotor blades with dissimilarity is investigated using the active twist concept and the optimal control theory. The induced shear strain on the actuation mechanism by the piezoelectric constant d 15 from the PZN–8% PT-based single-crystal material is used to achieve more active twisting to suppress the extra vibrations. The optimal control algorithm is based on the minimization of an objective function comprised of quadratic functions of vibratory hub loads and voltage control harmonics. The blade-to-blade dissimilarity is modeled using the stiffness degradation of composite blades. The optimal controller is applied to various possible dissimilarities arising from different damage patterns of composite blades. The governing equations of motion are derived using Hamilton's principle. The effects of composite materials and smart actuators are incorporated into the comprehensive aeroelastic analysis system. Numerical results showing the impact of addressing the blade dissimilarities on hub vibrations and voltage inputs required to suppress the vibrations are demonstrated. It is observed that all vibratory shear forces are reduced considerably and the major harmonics of moments are reduced significantly. However, the controller needs further improvement to suppress 1/rev moment loads. A mechanism to achieve vibration reduction for the dissimilar rotor system has also been identified

Active twist control methodology for vibration reduction of a helicopter with dissimilar rotor system

Science.gov (United States)

Pawar, Prashant M.; Jung, Sung Nam

2009-03-01

In this work, an active vibration reduction of hingeless composite rotor blades with dissimilarity is investigated using the active twist concept and the optimal control theory. The induced shear strain on the actuation mechanism by the piezoelectric constant d15 from the PZN-8% PT-based single-crystal material is used to achieve more active twisting to suppress the extra vibrations. The optimal control algorithm is based on the minimization of an objective function comprised of quadratic functions of vibratory hub loads and voltage control harmonics. The blade-to-blade dissimilarity is modeled using the stiffness degradation of composite blades. The optimal controller is applied to various possible dissimilarities arising from different damage patterns of composite blades. The governing equations of motion are derived using Hamilton's principle. The effects of composite materials and smart actuators are incorporated into the comprehensive aeroelastic analysis system. Numerical results showing the impact of addressing the blade dissimilarities on hub vibrations and voltage inputs required to suppress the vibrations are demonstrated. It is observed that all vibratory shear forces are reduced considerably and the major harmonics of moments are reduced significantly. However, the controller needs further improvement to suppress 1/rev moment loads. A mechanism to achieve vibration reduction for the dissimilar rotor system has also been identified.

Reduction of interior sound fields in flexible cylinders by active vibration control

Science.gov (United States)

Jones, J. D.; Fuller, C. R.

1988-01-01

The mechanisms of interior sound reduction through active control of a thin flexible shell's vibrational response are presently evaluated in view of an analytical model. The noise source is a single exterior acoustic monopole. The active control model is evaluated for harmonic excitation; the results obtained indicate spatially-averaged noise reductions in excess of 20 dB over the source plane, for acoustic resonant conditions inside the cavity.

Finite element analysis using NASTRAN applied to helicopter transmission vibration/noise reduction

Science.gov (United States)

Howells, R. W.; Sciarra, J. J.

1975-01-01

A finite element NASTRAN model of the complete forward rotor transmission housing for the Boeing Vertol CH-47 helicopter was developed and applied to reduce transmission vibration/noise at its source. In addition to a description of the model, a technique for vibration/noise prediction and reduction is outlined. Also included are the dynamic response as predicted by NASTRAN, test data, the use of strain energy methods to optimize the housing for minimum vibration/noise, and determination of design modifications which will be manufactured and tested. The techniques presented are not restricted to helicopters but are applicable to any power transmission system. The transmission housing model developed can be used further to evaluate static and dynamic stresses, thermal distortions, deflections and load paths, fail-safety/vulnerability, and composite materials.

Experimental study on titanium wire drawing with ultrasonic vibration.

Science.gov (United States)

Liu, Shen; Shan, Xiaobiao; Guo, Kai; Yang, Yuancai; Xie, Tao

2018-02-01

Titanium and its alloys have been widely used in aerospace and biomedical industries, however, they are classified as difficult-to-machine materials. In this paper, ultrasonic vibration is imposed on the die to overcome the difficulties during conventional titanium wire drawing processes at the room temperature. Numerical simulations were performed to investigate the variation of axial stress within the contacting region and study the change of the drawing stress with several factors in terms of the longitudinal amplitude and frequency of the applied ultrasonic vibration, the diameter reduction ratio, and the drawing force. An experimental testing equipment was established to measure the drawing torque and rotational velocity of the coiler drum during the wire drawing process. The result indicates the drawing force increases with the growth of the drawing velocity and the reduction ratio, whether with or without vibrations. Application of either form of ultrasonic vibrations contributes to the further decrease of the drawing force, especially the longitudinal vibration with larger amplitude. SEM was employed to detect the surface morphology of the processed wires drawn under the three circumstances. The surface quality of the drawn wires with ultrasonic vibrations was apparently improved compared with those using conventional method. In addition, the longitudinal and torsional composite vibration was more effective for surface quality improvement than pure longitudinal vibration, however, at the cost of weakened drawing force reduction effect. Copyright © 2017 Elsevier B.V. All rights reserved.

The Study of Vibration Processes in Oil Flooded Screw Compressors

Directory of Open Access Journals (Sweden)

I. V. Filippov

2014-01-01

Full Text Available Vibration processes that accompany most of machines and mechanisms are of interest to the researcher, as a source of information about the technical condition and the nature of the business processes flow. Vibration-based diagnostics of oil flooded screw compressors allows us to estimate the deviation of their operation from the main mode in accordance with changing the settings of vibration processes.The oil flooded screw compressor transition from the main mode of operation to the abnormal one is accompanied by complex gas-dynamic phenomena i.e. the initial gaps and their decays. This leads to changes in the nature of vibration processes, prompting suggestions that there is a relationship to a change of vibration parameters and mode of compressor operation.Studies were conducted by combined method using an analytical calculation of the decay parameters of the initial discontinuity and an experimental one based on the measurement of acceleration on the body of the real oil flooded screw compressor. A virtually adequate reaction of the decay parameters of the initial gap and the peak values of vibration acceleration to the change of operation mode of oil flooded screw compressor has been received. The peak value of the vibration acceleration was selected by the method of Gating being time-coinciding with the beginning discharge phase of the oil flooded screw compressor, and therefore, with the decay time of the initial discontinuity.This indicates a large degree of hypothesis likelihood on an existing initial break in oil flooded screw compressor when operating in abnormal conditions. This work contains the study results of vibration processes and their relationship to the operating mode of the oil flooded screw compressor, which distinguish it from the other works studied vibration processes in reciprocating compressors. The vibration parameters control of operating oil flooded screw compressor allows us to create an automatic capacity control

Optimal deployment schedule of an active twist rotor for performance enhancement and vibration reduction in high-speed flights

Directory of Open Access Journals (Sweden)

Young H. YOU

2017-08-01

Full Text Available The best active twist schedules exploiting various waveform types are sought taking advantage of the global search algorithm for the reduction of hub vibration and/or power required of a rotor in high-speed conditions. The active twist schedules include two non-harmonic inputs formed based on segmented step functions as well as the simple harmonic waveform input. An advanced Particle Swarm assisted Genetic Algorithm (PSGA is employed for the optimizer. A rotorcraft Computational Structural Dynamics (CSD code CAMRAD II is used to perform the rotor aeromechanics analysis. A Computation Fluid Dynamics (CFD code is coupled with CSD for verification and some physical insights. The PSGA optimization results are verified against the parameter sweep study performed using the harmonic actuation. The optimum twist schedules according to the performance and/or vibration reduction strategy are obtained and their optimization gains are compared between the actuation cases. A two-phase non-harmonic actuation schedule demonstrates the best outcome in decreasing the power required while a four-phase non-harmonic schedule results in the best vibration reduction as well as the simultaneous reductions in the power required and vibration. The mechanism of reduction to the performance gains is identified illustrating the section airloads, angle-of-attack distribution, and elastic twist deformation predicted by the present approaches.

Investigation of a vibration-damping unit for reduction in low-frequency vibrations of electric motors

Science.gov (United States)

Grigoryey, N. V.; Fedorovich, M. A.

1973-01-01

The vibroacoustical characteristics of different types of electric motors are discussed. It is shown that the basic source of low frequency vibrations is rotor unbalance. A flexible damping support, with an antivibrator, is used to obtain the vibroacoustical effect of reduction in the basic harmonic of the electric motor. A model of the electric motor and the damping apparatus is presented. Mathematical models are developed to show the relationships of the parameters. The basic purpose in using a calculation model id the simultaneous replacement of the exciting force created by the rotor unbalance and its inertial rigidity characteristics by a limiting kinematic disturbance.

Researches Concerning to Minimize Vibrations when Processing Normal Lathe

Directory of Open Access Journals (Sweden)

Lenuța Cîndea

2015-09-01

Full Text Available In the cutting process, vibration is inevitable appearance, and in situations where the amplitude exceeds the limits of precision dimensional and shape of the surfaces generated vibrator phenomenon is detrimental.Field vibration is an issue of increasingly developed, so the futures will a better understanding of them and their use even in other sectors.The paper developed experimental measurement of vibrations at the lathe machining normal. The scheme described kinematical machine tool, cutting tool, cutting conditions, presenting experimental facility for measuring vibration occurring at turning. Experimental results have followed measurement of amplitude, which occurs during interior turning the knife without silencer incorporated. The tests were performed continuously for different speed, feed and depth of cut.

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

Active vibration reduction by optimally placed sensors and actuators with application to stiffened plates by beams

International Nuclear Information System (INIS)

Daraji, A H; Hale, J M

2014-01-01

This study concerns new investigation of active vibration reduction of a stiffened plate bonded with discrete sensor/actuator pairs located optimally using genetic algorithms based on a developed finite element modeling. An isotropic plate element stiffened by a number of beam elements on its edges and having a piezoelectric sensor and actuator pair bonded to its surfaces is modeled using the finite element method and Hamilton’s principle, taking into account the effects of piezoelectric mass, stiffness and electromechanical coupling. The modeling is based on the first order shear deformation theory taking into account the effects of bending, membrane and shear deformation for the plate, the stiffening beam and the piezoelectric patches. A Matlab finite element program has been built for the stiffened plate model and verified with ANSYS and also experimentally. Optimal placement of ten piezoelectric sensor/actuator pairs and optimal feedback gain for active vibration reduction are investigated for a plate stiffened by two beams arranged in the form of a cross. The genetic algorithm was set up for optimization of sensor/actuator placement and feedback gain based on the minimization of the optimal linear quadratic index as an objective function to suppress the first six modes of vibration. Comparison study is presented for active vibration reduction of a square cantilever plate stiffened by crossed beams with two sensor/actuator configurations: firstly, ten piezoelectric sensor/actuator pairs are located in optimal positions; secondly, a piezoelectric layer of single sensor/actuator pair covering the whole of the stiffened plate as a SISO system. (paper)

A novel magnetorheological elastomer isolator with negative changing stiffness for vibration reduction

International Nuclear Information System (INIS)

Yang, J; Sun, S S; Li, W H; Alici, G; Du, H; Deng, H X

2014-01-01

Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart isolators and absorbers due to their controllable stiffness and damping properties. For the purpose of mitigating unwanted structural and/or machinery vibrations, the traditional MRE-based isolators have been generally proven effective because the MR effect can increase the stiffness when the magnetic field is strengthened. This study presents a novel MRE isolator that experienced reduced stiffness when the applied current was increased. This innovative work was accomplished by applying a hybrid magnet (electromagnet and permanent magnets) onto a multilayered MRE structure. To characterise this negative changing stiffness concept, a multilayered MRE isolator with a hybrid magnet was first designed, fabricated and then tested to measure its properties. An obvious reduction of the effective stiffness and natural frequency of the proposed MRE isolator occurred when the current was continuously adjusted. This device could also work as a conventional MRE isolator as its effective stiffness and natural frequency also increased when a negative current was applied. Further testing was carried out on a one-degree-of-freedom system to assess how effectively this device could isolate vibration. In this experiment, two cases were considered; in each case, the vibration of the primary system was obviously attenuated under ON-OFF control logic, thus demonstrating the feasibility of this novel design as an alternative adaptive vibration isolator. (paper)

Vibration reduction at the engine-pumps assembly of the main moderator system

International Nuclear Information System (INIS)

Holostencu, Adriana; Dinu, Marius

2005-01-01

vibrations, (solution efficiency checked using the calibrated model). In order to reduce the pump-motor assembly vibrations, the EUROTEST/ Stevenson recommendation was to install 6 viscous dampers VES- 100. The modifications were completed in Outage 2002. After dampers coupling a considerable reduction on motor vibration level was noticed. The value read in MCR decreased from 9 mm/s to 2,5 mm/s. The results were confirmed by independent local measurements perform in field by CNE- PROD, Stevenson and Bently- Nevada teams. At the same time a slight increase of the vibration on the discharge header was noticed. The vibration regime in the discharge header was analysed by Stevenson in order to asses the impact of increased vibration on the system pipes. The analysis was made in accordance with ASME OM -S/ G. The conclusion of this analysis is that the vibrations regime for the moderator system including pumps, motors and pipes induces loads below the endurance limits. The same solution was also implemented at Quinshan NPP and it will be applied at Cernavoda NPP Unit 2

Measuring the Amount of Mechanical Vibration During Lathe Processing

Directory of Open Access Journals (Sweden)

Štefánia SALOKYOVÁ

2015-06-01

Full Text Available The article provides basic information regarding the measurement and evaluation of mechanical vibration during the processing of material by lathe work. The lathe processing can be characterized as removing material by precisely defined tools. The results of the experimental part are values of the vibration acceleration amplitude measured by the piezoelectric sensor on the bearing house of the lathe. A set of new knowledge and conclusions is formulated based on the analysis of the created graphical dependencies.

The Investigations of Friction under Die Surface Vibration in Cold Forging Process

DEFF Research Database (Denmark)

Jinming, Sha

investigation, and the second stage is to design and manufacture a more practical tool system which can be used to forging some industrial components with larger capacity. The high performance and power piezoelectric actuator stack as the vibration source will be used for designing the vibration system in order...... to 50% with vibration being applied in forming process. Furthermore, by using finite element method, a series of the simulations of the cold forging process under die surface excitation have been implemented in order to further understand the influence of vibration on friction, especially the influence...

Fingers' vibration transmission and grip strength preservation performance of vibration reducing gloves.

Science.gov (United States)

Hamouda, K; Rakheja, S; Dewangan, K N; Marcotte, P

2018-01-01

The vibration isolation performances of vibration reducing (VR) gloves are invariably assessed in terms of power tools' handle vibration transmission to the palm of the hand using the method described in ISO 10819 (2013), while the nature of vibration transmitted to the fingers is ignored. Moreover, the VR gloves with relatively low stiffness viscoelastic materials affect the grip strength in an adverse manner. This study is aimed at performance assessments of 12 different VR gloves on the basis of handle vibration transmission to the palm and the fingers of the gloved hand, together with reduction in the grip strength. The gloves included 3 different air bladder, 3 gel, 3 hybrid, and 2 gel-foam gloves in addition to a leather glove. Two Velcro finger adapters, each instrumented with a three-axis accelerometer, were used to measure vibration responses of the index and middle fingers near the mid-phalanges. Vibration transmitted to the palm was measured using the standardized palm adapter. The vibration transmissibility responses of the VR gloves were measured in the laboratory using the instrumented cylindrical handle, also described in the standard, mounted on a vibration exciter. A total of 12 healthy male subjects participated in the study. The instrumented handle was also used to measure grip strength of the subjects with and without the VR gloves. The results of the study showed that the VR gloves, with only a few exceptions, attenuate handle vibration transmitted to the fingers only in the 10-200 Hz and amplify middle finger vibration at frequencies exceeding 200 Hz. Many of the gloves, however, provided considerable reduction in vibration transmitted to the palm, especially at higher frequencies. These suggest that the characteristics of vibration transmitted to fingers differ considerably from those at the palm. Four of the test gloves satisfied the screening criteria of the ISO 10819 (2013) based on the palm vibration alone, even though these caused

Reduction of vibration forces transmitted from a radiator cooling fan to a vehicle body

Science.gov (United States)

Lim, Jonghyuk; Sim, Woojeong; Yun, Seen; Lee, Dongkon; Chung, Jintai

2018-04-01

This article presents methods for reducing transmitted vibration forces caused by mass unbalance of the radiator cooling fan during vehicle idling. To identify the effects of mass unbalance upon the vibration characteristics, vibration signals of the fan blades were experimentally measured both with and without an added mass. For analyzing the vibration forces transmitted to the vehicle body, a dynamic simulation model was established that reflected the vibration characteristics of the actual system. This process included a method described herein for calculating the equivalent stiffness and the equivalent damping of the shroud stators and rubber mountings. The dynamic simulation model was verified by comparing its results with experimental results of the radiator cooling fan. The dynamic simulation model was used to analyze the transmitted vibration forces at the rubber mountings. Also, a measure was established to evaluate the effects of varying the design parameters upon the transmitted vibration forces. We present design guidelines based on these analyses to reduce the transmitted vibration forces of the radiator cooling fan.

Reduction method for residual stress of welded joint using harmonic vibrational load

International Nuclear Information System (INIS)

Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

2007-01-01

Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model

Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

Directory of Open Access Journals (Sweden)

Dong-Xu Li

2017-01-01

Full Text Available Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections between substructures. Especially in this paper, a vibration antiresonance design method is proposed to realize the vibration reduction. The complex zero-point equations of the vibration system are firstly established, and then the vibration antiresonance design for the system is achieved. For solving the difficulties due to viscoelastic characteristics of the connecting parts, we present the determining formulas to obtain the structural parameters, so that the complex zero-point equations can be satisfied. Numerical simulation and ground experiment demonstrate the correctness and effectiveness of the proposed method. This method can solve the structural vibration control problem under the function constraints of load bearing and energy supplying and will expand the performance of spacecraft functional modules.

Reduction of the radiating sound of a submerged finite cylindrical shell structure by active vibration control.

Science.gov (United States)

Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

2013-02-06

In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

Directory of Open Access Journals (Sweden)

Seung-Bok Choi

2013-02-01

Full Text Available In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

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.

Comparison of dimensionality reduction techniques for the fault diagnosis of mono block centrifugal pump using vibration signals

Directory of Open Access Journals (Sweden)

N.R. Sakthivel

2014-03-01

Full Text Available Bearing fault, Impeller fault, seal fault and cavitation are the main causes of breakdown in a mono block centrifugal pump and hence, the detection and diagnosis of these mechanical faults in a mono block centrifugal pump is very crucial for its reliable operation. Based on a continuous acquisition of signals with a data acquisition system, it is possible to classify the faults. This is achieved by the extraction of features from the measured data and employing data mining approaches to explore the structural information hidden in the signals acquired. In the present study, statistical features derived from the vibration data are used as the features. In order to increase the robustness of the classifier and to reduce the data processing load, dimensionality reduction is necessary. In this paper dimensionality reduction is performed using traditional dimensionality reduction techniques and nonlinear dimensionality reduction techniques. The effectiveness of each dimensionality reduction technique is also verified using visual analysis. The reduced feature set is then classified using a decision tree. The results obtained are compared with those generated by classifiers such as Naïve Bayes, Bayes Net and kNN. The effort is to bring out the better dimensionality reduction technique–classifier combination.

Noise and vibration reduction technology in hybrid vehicle development; Hybrid sha kaihatsu ni okeru shindo soon teigen gijutsu

Energy Technology Data Exchange (ETDEWEB)

Yoshioa, T.; Sugita, H. [Toyota Motor Corp., Aichi (Japan)

2000-03-01

Accomplishing both environmental protection and good NVH performance has become a significant task in automotive development The first-in-the-world hybrid passenger car of mass production. 'Prius', has achieved superior NV performance compared with conventional vehicles with a 1.5-liter engine along with 50% reduction of fuel consumption and CO{sub 2} emissions. low HC, CO and NO{sub x} emissions. This paper describes NV reduction technology for solving problems peculiar to the hybrid vehicle such as engine start/stop vibration, drone noise at low engine speed and motor/generator noise and vibration. It also mentions application technology of low rolling resistance tires with light weight wheels and recycled material for sound proofing. (author)

Ride comfort enhancement in railway vehicle by the reduction of the car body structural flexural vibration

Science.gov (United States)

Dumitriu, M.

2017-08-01

The paper approaches the issue of reduction in the vertical bending vibrations of the railway vehicle carbody and the ride comfort enhancement at high velocities, starting from the prospect of isolating the vibrations by the best possible selection of the passive suspension damping in the vehicle. To this purpose, the examination falls on the influence of the vertical suspension damping upon the vibrations regime of the vehicle at the bending resonance frequency and upon the ride comfort. The results of the numerical simulations regarding the frequency response of the carbody acceleration and the comfort index will be therefore used. A value of the secondary suspension damping can be thus identified that will provide the best ride comfort performance. Similarly, the ride comfort can be increased by raising the primary suspension damping ratio.

Quality status display for a vibration welding process

Science.gov (United States)

Spicer, John Patrick; Abell, Jeffrey A.; Wincek, Michael Anthony; Chakraborty, Debejyo; Bracey, Jennifer; Wang, Hui; Tavora, Peter W.; Davis, Jeffrey S.; Hutchinson, Daniel C.; Reardon, Ronald L.; Utz, Shawn

2017-11-28

A method includes receiving, during a vibration welding process, a set of sensory signals from a collection of sensors positioned with respect to a work piece during formation of a weld on or within the work piece. The method also includes receiving control signals from a welding controller during the process, with the control signals causing the welding horn to vibrate at a calibrated frequency, and processing the received sensory and control signals using a host machine. Additionally, the method includes displaying a predicted weld quality status on a surface of the work piece using a status projector. The method may include identifying and display a quality status of a suspect weld. The laser projector may project a laser beam directly onto or immediately adjacent to the suspect welds, e.g., as a red, green, blue laser or a gas laser having a switched color filter.

Power flow prediction in vibrating systems via model reduction

Science.gov (United States)

Li, Xianhui

This dissertation focuses on power flow prediction in vibrating systems. Reduced order models (ROMs) are built based on rational Krylov model reduction which preserve power flow information in the original systems over a specified frequency band. Stiffness and mass matrices of the ROMs are obtained by projecting the original system matrices onto the subspaces spanned by forced responses. A matrix-free algorithm is designed to construct ROMs directly from the power quantities at selected interpolation frequencies. Strategies for parallel implementation of the algorithm via message passing interface are proposed. The quality of ROMs is iteratively refined according to the error estimate based on residual norms. Band capacity is proposed to provide a priori estimate of the sizes of good quality ROMs. Frequency averaging is recast as ensemble averaging and Cauchy distribution is used to simplify the computation. Besides model reduction for deterministic systems, details of constructing ROMs for parametric and nonparametric random systems are also presented. Case studies have been conducted on testbeds from Harwell-Boeing collections. Input and coupling power flow are computed for the original systems and the ROMs. Good agreement is observed in all cases.

Applying Low-Frequency Vibration for the Experimental Investigation of Clutch Hub Forming

Directory of Open Access Journals (Sweden)

De’an Meng

2018-05-01

Full Text Available A vibration-assisted plastic-forming method was proposed, and its influence on clutch hub forming process was investigated. The experiments were conducted on a vibration-assisted hydraulic extrusion press with adjustable frequency and amplitude. Vibration frequency and amplitude were considered in investigating the effect of vibration on forming load and surface quality. Results showed that applying vibration can effectively reduce forming force and improve surface quality. The drop in forming load was proportional to the vibration frequency and amplitude, and the load decreased by up to 25%. Such reduction in forming load raised with amplitude increase because the increase in amplitude would accelerate punch relative speed, which then weakened the adhesion between workpiece and dies. By increasing the vibration frequency, the punch movement was enhanced, and the number of attempts to drag the lubricant out of the pits was increased. In this manner, the lubrication condition was improved greatly. The 3D surface topography testing confirmed the assumption. Moreover, vibration frequency exerted a more significant effect on the forming load reduction than vibration amplitude.

Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction

Science.gov (United States)

Shin, SangJoon; Cesnik, Carlos E. S.

2001-01-01

Active integral twist control for vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight conditions: frequency domain analysis for hover, and time domain analysis for forward flight. Both stem from the same three-dimensional electroelastic beam formulation with geometrical-exactness, and axe coupled with a finite-state dynamic inflow aerodynamics model. A prototype Active Twist Rotor blade was designed with this framework using Active Fiber Composites as the actuator. The ATR prototype blade was successfully tested under non-rotating conditions. Hover testing was conducted to evaluate structural integrity and dynamic response. In both conditions, a very good correlation was obtained against the analysis. Finally, a four-bladed ATR system is built and tested to demonstrate its concept in forward flight. This experiment was conducted at NASA Langley Tansonic Dynamics Tunnel and represents the first-of-a-kind Mach-scaled fully-active-twist rotor system to undergo forward flight test. In parallel, the impact upon the fixed- and rotating-system loads is estimated by the analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well. It was also shown, both experimentally and numerically, that the ATR blade design has the potential for hub vibratory load reduction of up to 90% using individual blade control actuation. Using the numerical framework, system identification is performed to estimate the harmonic transfer functions. The linear time-periodic system can be represented by a linear time-invariant system under the three modes of blade actuation: collective, longitudinal cyclic, and lateral cyclic. A vibration

Process energy reduction

International Nuclear Information System (INIS)

Lowthian, W.E.

1993-01-01

Process Energy Reduction (PER) is a demand-side energy reduction approach which complements and often supplants other traditional energy reduction methods such as conservation and heat recovery. Because the application of PER is less obvious than the traditional methods, it takes some time to learn the steps as well as practice to become proficient in its use. However, the benefit is significant, often far outweighing the traditional energy reduction approaches. Furthermore, the method usually results in a better process having less waste and pollution along with improved yields, increased capacity, and lower operating costs

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.

Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

OpenAIRE

Li, Dong-Xu; Liu, Wang; Hao, Dong

2017-01-01

Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections b...

Theoretical and Experimental Study on Vibration Propagation in PMMA Components in Ultrasonic Bonding Process

Directory of Open Access Journals (Sweden)

Yibo Sun

2017-03-01

Full Text Available Ultrasonic bonding has an increasing application in the micro assembly of polymeric micro-electro mechanical systems (MEMS with high requirements for fusion precision. In the ultrasonic bonding process, the propagation of ultrasonic vibration in polymer components is related to the interfacial fusion, which can be used as a monitoring parameter to control ultrasonic energy. To study the vibration propagation in viscoelastic polymer components, finite element analysis on the bonding of poly methyl methacrylate (PMMA micro connector to substrate for microfluidic system is carried out. Curves of propagated vibration amplitude corresponding to interfacial temperatures are obtained. The ultrasonic vibration propagated in PMMA components are measured through experiments. The theoretical and experimental results are contrasted to analyze the change mechanism of vibration propagation related to temperature. Based on the ultrasonic bonding process controlled by the feedback of vibration propagation, interfacial fusions at different vibration propagation states are obtained through experiments. Interfacial fusion behavior is contrasted to the propagated vibration amplitude in theoretical and experimental studies. The relation between vibration propagation and fusion degree is established with the proper parameter range for the obtained high quality bonding.

Rotor Vibration Reduction via Active Hybrid Bearings

DEFF Research Database (Denmark)

Nicoletti, Rodrigo; Santos, Ilmar

2002-01-01

The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

Handbook Of Noise And Vibration

International Nuclear Information System (INIS)

1995-12-01

This book is about noise and vibration. The first chapter has explanations of noise such as basic of sound, influence of noise, assessment of noise, measurement of prevention of noise and technology, case of noise measurement and soundproof. The second chapter describes vibration with outline, theory of vibration, interpretation of vibration, measurement for reduction of vibration, case of design of protection against vibration. It deals with related regulation and method of measurement.

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

Active Vibration Reduction of Titanium Alloy Fan Blades (FAN1) Using Piezoelectric Materials

Science.gov (United States)

Choi, Benjamin; Kauffman, Jeffrey; Duffy, Kirsten; Provenza, Andrew; Morrison, Carlos

2010-01-01

The NASA Glenn Research Center is developing smart adaptive structures to improve fan blade damping at resonances using piezoelectric (PE) transducers. In this paper, a digital resonant control technique emulating passive shunt circuits is used to demonstrate vibration reduction of FAN1 Ti real fan blade at the several target modes. Single-mode control and multi-mode control using one piezoelectric material are demonstrated. Also a conceptual study of how to implement this digital control system into the rotating fan blade is discussed.

Active vibration reduction of rigid rotor by kinematic excitation of bushes of journal bearings

Directory of Open Access Journals (Sweden)

J. Ondrouch

2010-04-01

Full Text Available Possibilities of active lateral vibration reduction of a symmetric, rigid rotor supported by journal bearings are given. They were obtained by computational modelling. Efficiency of the feedback P and PD controllers in the stable revolution interval was examined. The linearized rotor system model was used. The results of the theoretical analysis are assigned for a testing stand where the bearing bush motions are deactivated by piezoelectric actuators connected to the controllers.

Numerical investigation on vibration characteristics of a micro-speaker diaphragm considering thermoforming effects

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyeong Min; Park, Ke Un [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2013-10-15

Micro-speaker diaphragms play an important role in generating desired sound responses, and are designed to have thin membrane shapes for flexibility in the axial direction. The micro-speaker diaphragms are formed from thin polymer film through the thermoforming process, in which local thickness reductions occur due to strain localization. This thickness reduction results in a change in vibration characteristics of the diaphragm and different sound responses from that of the original design. In this study, the effect of this thickness change in the diaphragm on its vibration characteristics is numerically investigated by coupling thermoforming simulation, structural analysis and modal analysis. Thus, the thickness change in the diaphragm is calculated from the thermoforming simulation, and reflected in the further structural and modal analyses in order to estimate the relevant stiffness and vibration modes. Comparing these simulation results with those from a diaphragm with the uniform thickness, it is found that a local thickness reduction results in the stiffness reduction and the relevant change in the natural frequencies and the corresponding vibration modes.

Numerical investigation on vibration characteristics of a micro-speaker diaphragm considering thermoforming effects

International Nuclear Information System (INIS)

Kim, Kyeong Min; Park, Ke Un

2013-01-01

Micro-speaker diaphragms play an important role in generating desired sound responses, and are designed to have thin membrane shapes for flexibility in the axial direction. The micro-speaker diaphragms are formed from thin polymer film through the thermoforming process, in which local thickness reductions occur due to strain localization. This thickness reduction results in a change in vibration characteristics of the diaphragm and different sound responses from that of the original design. In this study, the effect of this thickness change in the diaphragm on its vibration characteristics is numerically investigated by coupling thermoforming simulation, structural analysis and modal analysis. Thus, the thickness change in the diaphragm is calculated from the thermoforming simulation, and reflected in the further structural and modal analyses in order to estimate the relevant stiffness and vibration modes. Comparing these simulation results with those from a diaphragm with the uniform thickness, it is found that a local thickness reduction results in the stiffness reduction and the relevant change in the natural frequencies and the corresponding vibration modes.

Isotope separation process by transfer of vibrational energy

International Nuclear Information System (INIS)

Angelie, C.; Cauchetier, M.; Paris, J.

1983-01-01

This process consists in exciting A molecules by absorption of a pulsed light beam, then in exciting until their dissociation X molecules, present in several isotopic forms, by a vibrational transfer between the A molecules and the X molecules, the A molecules having a dissociation energy greater than that of the X molecules, the duration and energy of the light pulses being such that the absorption time by the A molecules is less than the excitation time of the X molecules and the temperature conditions such that the thermal width of the vibration rays is at the most near the isotopic difference between the resonance rays of the two isotopic varieties [fr

Study on design method and vibration reduction characteristic of floating raft with periodic structure

Science.gov (United States)

Fang, Yuanyuan; Zuo, Yanyan; Xia, Zhaowang

2018-03-01

The noise level is getting higher with the development of high-power marine power plant. Mechanical noise is one of the most obvious noise sources which not only affect equipment reliability, riding comfort and working environment, but also enlarge underwater noise. The periodic truss type device which is commonly applied in fields of aerospace and architectural is introduced to floating raft construction in ship. Four different raft frame structure are designed in the paper. The vibration transmissibility is taken as an evaluation index to measure vibration isolation effect. A design scheme with the best vibration isolation effect is found by numerical method. Plate type and the optimized periodic truss type raft frame structure are processed to experimental verify vibration isolation effect of the structure of the periodic raft. The experimental results demonstrate that the same quality of the periodic truss floating raft has better isolation effect than that of the plate type floating raft.

THE REDUCTION OF VIBRATIONS IN A CAR – THE PRINCIPLE OF PNEUMATIC DUAL MASS FLYWHEEL

Directory of Open Access Journals (Sweden)

Robert GREGA

2014-09-01

Full Text Available The dual-mass flywheel replaces the classic flywheel in such way that it is divided into two masses (the primary mass and the secondary mass, which are jointed together by means of a flexible interconnection. This kind of the flywheel solution enables to change resonance areas of the engine with regard to the engine dynamic behaviour what leads to a reduction of vibrations consequently. However, there is also a disadvantage of the dualmass flywheels. The disadvantage is its short-time durability. There was projected a new type of the dual-mass flywheel in the framework of our workplace in order to eliminate disadvantages of the present dual-mass flywheels, i.e. we projected the pneumatic dual-mass flywheel, taking into consideration our experiences obtained during investigation of vibrations.

Novel active vibration absorber with magnetorheological fluid

Energy Technology Data Exchange (ETDEWEB)

Gerlach, T; Ehrlich, J; Boese, H [Fraunhofer-Institut fuer Silicatforschung ISC, Neunerplatz 2, D-97082 Wuerzburg (Germany)], E-mail: thomas.gerlach@isc.fraunhofer.de

2009-02-01

Disturbing vibrations diminish the performance of technical high precision devices significantly. In search of a suitable solution for reducing these vibrations, a novel concept of active vibration reduction was developed which exploits the special properties of magnetorheological fluids. In order to evaluate the concept of such an active vibration absorber (AVA) a demonstrator was designed and manufactured. This demonstrator generates a force which counteracts the motion of the vibrating body. Since the counterforce is generated by a centrifugal exciter, the AVA provides the capability to compensate vibrations even in two dimensions. To control the strength of the force transmitted to the vibrating body, the exciter is based on a tunable MR coupling. The AVA was integrated in an appropriate testing device to investigate its performance. The recorded results show a significant reduction of the vibration amplitudes by an order of magnitude.

Environmental vibration reduction utilizing an array of mass scatterers

DEFF Research Database (Denmark)

Peplow, Andrew; Andersen, Lars Vabbersgaard; Bucinskas, Paulius

2017-01-01

.g. concrete or stone blocks, specially designed brick walls, etc.). The natural frequencies of vibration for such blocks depend on the local ground stiffness and on the mass of the blocks which can be chosen to provide resonance at specified frequencies. This work concerns the effectiveness of such “blocking......Ground vibration generated by rail and road traffic is a major source of environmental noise and vibration pollution in the low-frequency range. A promising and cost effective mitigation method can be the use of heavy masses placed as a periodic array on the ground surface near the road or track (e...

Quantitative Diagnosis of Rotor Vibration Fault Using Process Power Spectrum Entropy and Support Vector Machine Method

Directory of Open Access Journals (Sweden)

Cheng-Wei Fei

2014-01-01

Full Text Available To improve the diagnosis capacity of rotor vibration fault in stochastic process, an effective fault diagnosis method (named Process Power Spectrum Entropy (PPSE and Support Vector Machine (SVM (PPSE-SVM, for short method was proposed. The fault diagnosis model of PPSE-SVM was established by fusing PPSE method and SVM theory. Based on the simulation experiment of rotor vibration fault, process data for four typical vibration faults (rotor imbalance, shaft misalignment, rotor-stator rubbing, and pedestal looseness were collected under multipoint (multiple channels and multispeed. By using PPSE method, the PPSE values of these data were extracted as fault feature vectors to establish the SVM model of rotor vibration fault diagnosis. From rotor vibration fault diagnosis, the results demonstrate that the proposed method possesses high precision, good learning ability, good generalization ability, and strong fault-tolerant ability (robustness in four aspects of distinguishing fault types, fault severity, fault location, and noise immunity of rotor stochastic vibration. This paper presents a novel method (PPSE-SVM for rotor vibration fault diagnosis and real-time vibration monitoring. The presented effort is promising to improve the fault diagnosis precision of rotating machinery like gas turbine.

CONDITIONS FOR STABLE CHIP BREAKING AND PROVISION OF MACHINED SURFACE QUALITY WHILE TURNING WITH ASYMMETRIC TOOL VIBRATIONS

Directory of Open Access Journals (Sweden)

V. K. Sheleh

2015-01-01

Full Text Available The paper considers a process of turning structural steel with asymmetric tool vibrations directed along feeding. Asymmetric vibrations characterized by asymmetry coefficient of vibration cycle, their frequency and amplitude are additionally transferred to the tool in the turning process with the purpose to crush chips. Conditions of stable chip breaking and obtaining optimum dimensions of chip elements have been determined in the paper. In order to reduce a negative impact of the vibration amplitude on a cutting process and quality of the machined surfaces machining must be carried out with its minimum value. In this case certain ratio of the tool vibration frequency to the work-piece rotation speed has been ensured in the paper. A formula has been obtained for calculation of this ratio with due account of the expected length of chip elements and coefficient of vibration cycle asymmetry.Influence of the asymmetric coefficient of the tool vibration cycle on roughness of the machined surfaces and cutting tool wear has been determined in the paper. According to the results pertaining to machining of work-pieces made of 45 and ШХ15 steel the paper presents mathematical relationships of machined surface roughness with cutting modes and asymmetry coefficient of tool vibration cycle. Tool feeding being one of the cutting modes exerts the most significant impact on the roughness value and increase of the tool feeding entails increase in roughness. Reduction in coefficient of vibration cycle asymmetry contributes to surface roughness reduction. However, the cutting tool wear occurs more intensive. Coefficient of the vibration cycle asymmetry must be increased in order to reduce wear rate. Therefore, the choice of the coefficient of the vibration cycle asymmetry is based on the parameters of surface roughness which must be obtained after machining and intensity of tool wear rate.The paper considers a process of turning structural steel with asymmetric

An Assessment of Using Vibrational Compaction of Calcined HLW and LLW in DWPF Canisters

International Nuclear Information System (INIS)

Yi, Yun-Bo; Amme, Robert C.; Shayer, Zeev

2008-01-01

Since 1963, the INEL has calcined almost 8 million gallons of liquid mixed waste and liquid high-level waste, converting it to some 1.1 million gallons of dry calcine (about 4275.0 m3), which consists of alumina-and zirconia-based calcine and zirconia-sodium blend calcine. In addition, if all existing and projected future liquid wastes are solidified, approximately 2,000 m3 of additional calcine will be produced primarily from sodium-bearing waste. Calcine is a more desirable material to store than liquid radioactive waste because it reduces volume, is much less corrosive, less chemically reactive, less mobile under most conditions, easier to monitor and more protective of human health and the environment. This paper describes the technical issue involved in the development of a feasible solution for further volume reduction of calcined nuclear waste for transportation and long term storage, using a standard DWPF canister. This will be accomplished by developing a process wherein the canisters are transported into a vibrational machine, for further volume reduction by about 35%. The random compaction experiments show that this volume reduction is achievable. The main goal of this paper is to demonstrate through computer modeling that it is feasible to use volume reduction vibrational machine without developing stress/strain forces that will weaken the canister integrity. Specifically, the paper presents preliminary results of the stress/strain analysis of the DWPF canister as a function of granular calcined height during the compaction and verifying that the integrity of the canister is not compromised. This preliminary study will lead to the development of better technology for safe compactions of nuclear waste that will have significant economical impact on nuclear waste storage and treatment. The preliminary results will guide us to find better solutions to the following questions: 1) What are the optimum locations and directions (vertical versus horizontal or

Anti-vibration gloves?

Science.gov (United States)

Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

2015-03-01

For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered. © Crown copyright 2014.

Lateral vibration behavior analysis and TLD vibration absorption design of the soft yoke single-point mooring system

Science.gov (United States)

Lyu, Bai-cheng; Wu, Wen-hua; Yao, Wei-an; Du, Yu

2017-06-01

Mooring system is the key equipment of FPSO safe operation. The soft yoke mooring system is regarded as one of the best shallow water mooring strategies and widely applied to the oil exploitation in the Bohai Bay in China and the Gulf of Mexico. Based on the analysis of numerous monitoring data obtained by the prototype monitoring system of one FPSO in the Bohai Bay, the on-site lateral vibration behaviors found on the site of the soft yoke subject to wave load were analyzed. ADAMS simulation and model experiment were utilized to analyze the soft yoke lateral vibration and it was determined that lateral vibration was resonance behaviors caused by wave excitation. On the basis of the soft yoke longitudinal restoring force being guaranteed, a TLD-based vibration damper system was constructed and the vibration reduction experiments with multi-tank space and multi-load conditions were developed. The experimental results demonstrated that the proposed TLD vibration reduction system can effectively reduce lateral vibration of soft yoke structures.

Reduction of vibrational interference from the iron core on HBTXIA

International Nuclear Information System (INIS)

Wilcock, P.D.

1981-01-01

The HBTXIA machine is a toroidal reversed field pinch which utilises a 1 volt second iron core. This paper looks briefly at the sources of vibration from the iron core and describes the design of a novel support system that has been installed to minimise the transmission of vibration to plasma diagnostics and other equipment during the machine pulse. Vibration measurements on the completed installation when the core is driven to saturation are reported and compared with calculations for a ground mounted core. (author)

Integrated vibration-based maintenance: an approach for continuous reduction in LCC. A case study

Energy Technology Data Exchange (ETDEWEB)

Najjar, B [ER Konsult Utveckling AB, Vaexjoe (Sweden)

1999-12-31

The biggest thread in achieving and maintaining high equipment effectiveness can be stated as: whether the improved manufacturing processes capable of producing quality products at a competitive cost. The effect of a new vibration-based maintenance concept, called Total Quality Maintenance (TQMain), is introduced. It aims to make intensive use of the real-time data acquisition and analysis to detect causes behind product quality deviation and failures in machinery, and following defect development at an early stage to increase machine mean effective life and improve company`s economics. The effect of TQMain on LCC of machinery and company`s economics is discussed. A case study to reveal savings in maintenance cost when a vibration-based policy involved, is presented. Using TQMain, company`s economics can be improved effectively through continuous improvement of the technical and economic effectiveness of production processes. (orig.) 14 refs.

Integrated vibration-based maintenance: an approach for continuous reduction in LCC. A case study

Energy Technology Data Exchange (ETDEWEB)

Najjar, B. [ER Konsult Utveckling AB, Vaexjoe (Sweden)

1998-12-31

The biggest thread in achieving and maintaining high equipment effectiveness can be stated as: whether the improved manufacturing processes capable of producing quality products at a competitive cost. The effect of a new vibration-based maintenance concept, called Total Quality Maintenance (TQMain), is introduced. It aims to make intensive use of the real-time data acquisition and analysis to detect causes behind product quality deviation and failures in machinery, and following defect development at an early stage to increase machine mean effective life and improve company`s economics. The effect of TQMain on LCC of machinery and company`s economics is discussed. A case study to reveal savings in maintenance cost when a vibration-based policy involved, is presented. Using TQMain, company`s economics can be improved effectively through continuous improvement of the technical and economic effectiveness of production processes. (orig.) 14 refs.

Transport processes and sound velocity in vibrationally non-equilibrium gas of anharmonic oscillators

Science.gov (United States)

Rydalevskaya, Maria A.; Voroshilova, Yulia N.

2018-05-01

Vibrationally non-equilibrium flows of chemically homogeneous diatomic gases are considered under the conditions that the distribution of the molecules over vibrational levels differs significantly from the Boltzmann distribution. In such flows, molecular collisions can be divided into two groups: the first group corresponds to "rapid" microscopic processes whereas the second one corresponds to "slow" microscopic processes (their rate is comparable to or larger than that of gasdynamic parameters variation). The collisions of the first group form quasi-stationary vibrationally non-equilibrium distribution functions. The model kinetic equations are used to study the transport processes under these conditions. In these equations, the BGK-type approximation is used to model only the collision operators of the first group. It allows us to simplify derivation of the transport fluxes and calculation of the kinetic coefficients. Special attention is given to the connection between the formulae for the bulk viscosity coefficient and the sound velocity square.

Experimental chaos in nonlinear vibration isolation system

International Nuclear Information System (INIS)

Lou Jingjun; Zhu Shijian; He Lin; He Qiwei

2009-01-01

The chaotic vibration isolation method was studied thoroughly from an experimental perspective. The nonlinear load-deflection characteristic of the conical coil spring used in the experiment was surveyed. Chaos and subharmonic responses including period-2 and period-6 motions were observed. The line spectrum reduction and the drop of the acceleration vibration level in chaotic state and that in non-chaotic state were compared, respectively. It was concluded from the experiment that the nonlinear vibration isolation system in chaotic state has strong ability in line spectrum reduction.

Energy distribution in selected fragment vibrations in dissociation processes in polyatomic molecules

International Nuclear Information System (INIS)

Band, Y.B.; Freed, K.F.

1977-01-01

The full quantum theory of dissociation processes in polyatomic molecules is converted to a form enabling the isolation of a selected fragment vibration. This form enables the easy evaluation of the probability distribution for energy partitioning between this vibration and all other degrees of freedom that results from the sudden Franck--Condon rearrangement process. The resultant Franck--Condon factors involve the square of the one-dimensional overlap integral between effective oscillator wavefunctions and the wavefunctions for the selected fragment vibration, a form that resembles the simple golden rule model for polyatomic dissociation and reaction processes. The full quantum theory can, therefore, be viewed as providing both a rigorous justification for certain generic aspects of the simple golden rule model as well as providing a number of important generalizations thereof. Some of these involve dealing with initial bound state vibrational excitation, explicit molecule, fragment and energy dependence of the effective oscillator, and the incorporation of all isotopic dependence. In certain limiting situations the full quantum theory yields simple, readily usable analytic expressions for the frequency and equilibrium position of the effective oscillator. Specific applications are presented for the direct photodissociation of HCN, DCN, and CO 2 where comparisons between the full theory and the simple golden rule are presented. We also discuss the generalizations of the previous theory to enable the incorporation of effects of distortion in the normal modes as a function of the reaction coordinate on the repulsive potential energy surface

Comparison of sEMG processing methods during whole-body vibration exercise.

Science.gov (United States)

Lienhard, Karin; Cabasson, Aline; Meste, Olivier; Colson, Serge S

2015-12-01

The objective was to investigate the influence of surface electromyography (sEMG) processing methods on the quantification of muscle activity during whole-body vibration (WBV) exercises. sEMG activity was recorded while the participants performed squats on the platform with and without WBV. The spikes observed in the sEMG spectrum at the vibration frequency and its harmonics were deleted using state-of-the-art methods, i.e. (1) a band-stop filter, (2) a band-pass filter, and (3) spectral linear interpolation. The same filtering methods were applied on the sEMG during the no-vibration trial. The linear interpolation method showed the highest intraclass correlation coefficients (no vibration: 0.999, WBV: 0.757-0.979) with the comparison measure (unfiltered sEMG during the no-vibration trial), followed by the band-stop filter (no vibration: 0.929-0.975, WBV: 0.661-0.938). While both methods introduced a systematic bias (P interpolation method and the band-stop filter was comparable. The band-pass filter was in poor agreement with the other methods (ICC: 0.207-0.697), unless the sEMG(RMS) was corrected for the bias (ICC ⩾ 0.931, %LOA ⩽ 32.3). In conclusion, spectral linear interpolation or a band-stop filter centered at the vibration frequency and its multiple harmonics should be applied to delete the artifacts in the sEMG signals during WBV. With the use of a band-stop filter it is recommended to correct the sEMG(RMS) for the bias as this procedure improved its performance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Vibration-processing interneurons in the honeybee brain

Directory of Open Access Journals (Sweden)

Hiroyuki Ai

2010-01-01

Full Text Available The afferents of the Johnston’s organ (JO in the honeybee brain send their axons to three distinct areas, the dorsal lobe, the dorsal subesophageal ganglion (DL-dSEG, and the posterior protocerebral lobe (PPL, suggesting that vibratory signals detected by the JO are processed differentially in these primary sensory centers. The morphological and physiological characteristics of interneurons arborizing in these areas were studied by intracellular recording and staining. DL-Int-1 and DL-Int-2 have dense arborizations in the DL-dSEG and respond to vibratory stimulation applied to the JO in either tonic excitatory, on-off-phasic excitatory, or tonic inhibitory patterns. PPL-D-1 has dense arborizations in the PPL, sends axons into the ventral nerve cord (VNC, and responds to vibratory stimulation and olfactory stimulation simultaneously applied to the antennae in long-lasting excitatory pattern. These results show that there are at least two parallel pathways for vibration processing through the DL-dSEG and the PPL. In this study, Honeybee Standard Brain was used as the common reference, and the morphology of two types of interneurons (DL-Int-1 and DL-Int-2 and JO afferents was merged into the standard brain based on the boundary of several neuropiles, greatly supporting the understanding of the spatial relationship between these identified neurons and JO afferents. The visualization of the region where the JO afferents are closely appositioned to these DL interneurons demonstrated the difference in putative synaptic regions between the JO afferents and these DL interneurons (DL-Int-1 and DL-Int-2 in the DL. The neural circuits related to the vibration-processing interneurons are discussed.

IN-SITU TEST OF PRESSURE PIPELINE VIBRATION BASED ON DATA ACQUISITION AND SIGNAL PROCESSING

OpenAIRE

Hou, Huimin; Xu, Cundong; Liu, Hui; Wang, Rongrong; Jie, Junkun; Ding, Lianying

2015-01-01

Pipeline vibration of high frequency and large amplitude is an important factor that impacts the safe operation of pumping station and the efficiency of the pumps. Through conducting the vibration in-situ test of pipeline system in the pumping station, we can objectively analyze the mechanism of pipeline vibration and evaluate the stability of pipeline operation. By using DASP (data acquisition & signal processing) in the in-situ test on the 2# pipeline of the third pumping station in the gen...

Electrochemical Reduction Process for Pyroprocessing

Energy Technology Data Exchange (ETDEWEB)

Choi, Eun-Young; Hong, Sun-Seok; Park, Wooshin; Im, Hun Suk; Oh, Seung-Chul; Won, Chan Yeon; Cha, Ju-Sun; Hur, Jin-Mok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-06-15

Nuclear energy is expected to meet the growing energy demand while avoiding CO{sub 2} emission. However, the problem of accumulating spent fuel from current nuclear power plants which is mainly composed of uranium oxides should be addressed. One of the most practical solutions is to reduce the spent oxide fuel and recycle it. Next-generation fuel cycles demand innovative features such as a reduction of the environmental load, improved safety, efficient recycling of resources, and feasible economics. Pyroprocessing based on molten salt electrolysis is one of the key technologies for reducing the amount of spent nuclear fuel and destroying toxic waste products, such as the long-life fission products. The oxide reduction process based on the electrochemical reduction in a LiCl-Li{sub 2}O electrolyte has been developed for the volume reduction of PWR (Pressurized Water Reactor) spent fuels and for providing metal feeds for the electrorefining process. To speed up the electrochemical reduction process, the influences of the feed form for the cathode and the type of anode shroud on the reduction rate were investigated.

State of the direct reduction and reduction smelting processes

Directory of Open Access Journals (Sweden)

Markotić A.

2002-01-01

Full Text Available For quite a long time efforts have been made to develop processes for producing iron i.e. steel without employing conventional procedures - from ore, coke, blast furnace, iron, electric arc furnace, converter to steel. The insufficient availability and the high price of the coking coals have forced many countries to research and adopt the non-coke-consuming reduction and metal manufacturing processes (non-coke metallurgy, direct reduction, direct processes. This paper represents a survey of the most relevant processes from this domain by the end of 2000, which display a constant increase in the modern process metallurgy.

VIBRATION REDUCTION ON SINGLE-LINK FLEXIBLE MANIPULATOR USING H∞ CONTROL

Directory of Open Access Journals (Sweden)

Roberd Saragih

2012-06-01

Full Text Available This paper is concerned with the vibration and position control of a single link flexible manipulator. Robot link manipulators are widely used in various industrial applications. It is desirable to build light weight flexible manipulators. Light flexible manipulators have a variety of applications, most significantly in space exploration,manufacturing automation, construction, mining, and hazardous operation. Timoshenko beam theory is used to derive mathematical model of a flexible manipulator. The dynamic equations of motion are obtained using the Lagrange's formulation of dynamics.The H∞ controller is designed for vibration and position control of the system. Simulations are presented and show that vibration and position control of a single flexible link can be controlled with the designed H∞ controller.

Dynamic Characteristics of Buildings from Signal Processing of Ambient Vibration

Science.gov (United States)

Dobre, Daniela; Sorin Dragomir, Claudiu

2017-10-01

The experimental technique used to determine the dynamic characteristics of buildings is based on records of low intensity oscillations of the building produced by various natural factors, such as permanent agitation type microseismic motions, city traffic, wind etc. The possibility of recording these oscillations is provided by the latest seismic stations (Geosig and Kinemetrics digital accelerographs). The permanent microseismic agitation of the soil is a complex form of stationary random oscillations. The building filters the soil excitation, selects and increases the components of disruptive vibrations corresponding to its natural vibration periods. For some selected buildings, with different instrumentation schemes for the location of sensors (in free-field, at basement, ground floor, roof level), a correlation between the dynamic characteristics resulted from signal processing of ambient vibration and from a theoretical analysis will be presented. The interpretation of recording results could highlight the behavior of the whole structure. On the other hand, these results are compared with those from strong motions, or obtained from a complex dynamic analysis, and they are quite different, but they are explicable.

Experimental Investigation into Vibration Characteristics for Damage Minimization in a Lapping Process

Directory of Open Access Journals (Sweden)

J. Suwatthikul

2016-01-01

Full Text Available Lapping machines are used in a hard disk rough lapping process where a workpiece (a wafer row bar is locked with a robot arm and rubbed on a lap plate. In this process, the lap plate’s condition and lifetime are among important concerned factors. The lifetime can be too short due to the plate being accidentally scratched by the workpiece during lapping. This problem leads to undesired consequences such as machine downtime and excessive plate material usage. This paper presents an experimental investigation into vibration characteristics of passed and failed lapping scenarios and discusses a potential solution to minimize the serious damage so-called “plate scratch” which intermittently occurs in such process. The experimental results show that, by in situ monitoring vibration and utilizing artificial intelligence, damage minimization can be possible.

Intermittent whole-body vibration attenuates a reduction in the number of the capillaries in unloaded rat skeletal muscle.

Science.gov (United States)

Kaneguchi, Akinori; Ozawa, Junya; Kawamata, Seiichi; Kurose, Tomoyuki; Yamaoka, Kaoru

2014-09-26

Whole-body vibration has been suggested for the prevention of muscle mass loss and muscle wasting as an attractive measure for disuse atrophy. This study examined the effects of daily intermittent whole-body vibration and weight bearing during hindlimb suspension on capillary number and muscle atrophy in rat skeletal muscles. Sixty male Wistar rats were randomly divided into four groups: control (CONT), hindlimb suspension (HS), HS + weight bearing (WB), and HS + whole-body vibration (VIB) (n = 15 each). Hindlimb suspension was applied for 2 weeks in HS, HS + WB, and HS + VIB groups. During suspension, rats in HS + VIB group were placed daily on a vibrating whole-body vibration platform for 20 min. In HS + WB group, suspension was interrupted for 20 min/day, allowing weight bearing. Untreated rats were used as controls. Soleus muscle wet weights and muscle fiber cross-sectional areas (CSA) significantly decreased in HS, HS + WB, and HS + VIB groups compared with CONT group. Both muscle weights and CSA were significantly greater in HS + WB and HS + VIB groups compared with HS group. Capillary numbers (represented by capillary-to-muscle fiber ratio) were significantly smaller in all hindlimb suspension-treated groups compared with CONT group. However, a reduction in capillary number by unloading hindlimbs was partially prevented by whole-body vibration. These findings were supported by examining mRNA for angiogenic-related factors. Expression levels of a pro-angiogenic factor, vascular endothelial growth factor-A mRNA, were significantly lower in all hindlimb suspension-treated groups compared with CONT group. There were no differences among hindlimb suspension-treated groups. Expression levels of an anti-angiogenic factor, CD36 (receptor for thrombospondin-1) mRNA, were significantly higher in all hindlimb suspension-treated groups compared with CONT group. Among the hindlimb suspension-treated groups, expression of CD

Vibrational inelastic and charge transfer processes in H++H2 system: An ab initio study

Science.gov (United States)

Amaran, Saieswari; Kumar, Sanjay

2007-12-01

State-resolved differential cross sections, total and integral cross sections, average vibrational energy transfer, and the relative probabilities are computed for the H++H2 system using the newly obtained ab initio potential energy surfaces at the full CI/cc-pVQZ level of accuracy which allow for both the direct vibrational inelastic and the charge transfer processes. The quantum dynamics is treated within the vibrational close-coupling infinite-order-sudden approximation approach using the two ab initio quasidiabatic potential energy surfaces. The computed collision attributes for both the processes are compared with the available state-to-state scattering experiments at Ec.m.=20eV. The results are in overall good agreement with most of the observed scattering features such as rainbow positions, integral cross sections, and relative vibrational energy transfers. A comparison with the earlier theoretical study carried out on the semiempirical surfaces (diatomics in molecules) is also made to illustrate the reliability of the potential energy surfaces used in the present work.

Evaluation of protective gloves and working techniques for reducing hand-arm vibration exposure in the workplace.

Science.gov (United States)

Milosevic, Matija; McConville, Kristiina M Valter

2012-01-01

Operation of handheld power tools results in exposure to hand-arm vibrations, which over time lead to numerous health complications. The objective of this study was to evaluate protective equipment and working techniques for the reduction of vibration exposure. Vibration transmissions were recorded during different work techniques: with one- and two-handed grip, while wearing protective gloves (standard, air and anti-vibration gloves) and while holding a foam-covered tool handle. The effect was examined by analyzing the reduction of transmitted vibrations at the wrist. The vibration transmission was recorded with a portable device using a triaxial accelerometer. The results suggest large and significant reductions of vibration with appropriate safety equipment. Reductions of 85.6% were achieved when anti-vibration gloves were used. Our results indicated that transmitted vibrations were affected by several factors and could be measured and significantly reduced.

Vibrations of rotating machinery

CERN Document Server

Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

2017-01-01

This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

Monitoring the intensity of mechanical vibration during the processing of chrome steel 14109

Directory of Open Access Journals (Sweden)

Š. Salokyová

2017-01-01

Full Text Available Article deals with the examination of the effect of cutting parameters on the occurrence and size of mechanical vibration on three selected measured points during the processing of chrome steel. It also includes execution, experiment evaluation in this field and comparison of measured vibrations acceleration amplitude values according to the standards. The results of the measurement serve for early identification of a defect, which has great effect on the smoothness and efficiency of the machine. The article concludes with the proposed new findings from the measured values evaluation and formulated new recommendations for the operation in production system with lathe turning technology. The measured experimental values of the acceleration amplitude of mechanical vibrations were compared with theoretical values.

Free vibration analysis of corroded steel plates

Energy Technology Data Exchange (ETDEWEB)

Eslami-Majd, Alireza; Rahbar-Ranji, Ahmad [AmirKabir University of Technology, Tehran (Iran, Islamic Republic of)

2014-06-15

Vibration analysis of unstiffened/stiffened plates has long been studied due to its importance in the design and condition assessments of ship and offshore structures. Corrosion is inevitable in steel structures and has been so far considered in strength analysis of structures. We studied the free vibration of pitted corroded plates with simply supported boundary conditions. Finite element analysis, with ABAQUS, was used to determine the natural frequencies and mode shapes of corroded plates. Influential parameters including plate aspect ratio, degree of pit, one-sided/both-sided corroded plate, and different corrosion patterns were investigated. By increasing the degree of corrosion, reduction of natural frequency increases. Plate aspect ratio and plate dimensions have no influence on reduction of natural frequency. Different corrosion patterns on the surface of one-sided corroded plates have little influence on reduction of natural frequency. Ratio of pit depth over plate thickness has no influence on the reduction of natural frequency. The reduction of natural frequency in both-sided corroded plates is higher than one-sided corroded plates with the same amount of total corrosion loss. Mode shapes of vibration would change due to corrosion, except square mode shapes.

Ground test for vibration control demonstrator

Science.gov (United States)

Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

2016-09-01

In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

Identification and reduction of vibration and noise of a glass tempering system

International Nuclear Information System (INIS)

Ashhab, M S

2015-01-01

The vibration and noise of a glass tempering machine at a factory are studied. Experiments were conducted to identify the sources of vibration and noise. It was found that main sources for vibration and noise are two air barrels, the air pipes from the fans to the glass tempering machine and the fans location. Solutions were suggested to reduce vibration and noise from these three main sources. One of the solutions that were implemented is placing rubber dampers beneath the air barrels and pipes which almost cancelled the horizontal vibrations in the building structure and reduced the vertical vibrations to a low value most likely coming from noise. There are two types of noise, namely, radiation noise from the fans through the fans room walls and transmitted noise through the pipes caused by turbulence. A glass wool noise insulating layer was installed on the wall between the fans room and factory to reduce radiation noise through this wall. Part of the air pipe system in the factory is made of a light material which produced the highest levels of noise above 110 dBA. These air pipes were wrapped by glass wool rolls and the noise level near them was reduced to below 100 dBA which comes from other machine parts. In addition, noise levels were reduced between 2 and 15 dBA at different points in the factory. (paper)

Application of lithium in molten-salt reduction processes

International Nuclear Information System (INIS)

Gourishankar, K. V.

1998-01-01

Metallothermic reductions have been extensively studied in the field of extractive metallurgy. At Argonne National Laboratory (ANL), we have developed a molten-salt based reduction process using lithium. This process was originally developed to reduce actinide oxides present in spent nuclear fuel. Preliminary thermodynamic considerations indicate that this process has the potential to be adapted for the extraction of other metals. The reduction is carried out at 650 C in a molten-salt (LiCl) medium. Lithium oxide (Li 2 O), produced during the reduction of the actinide oxides, dissolves in the molten salt. At the end of the reduction step, the lithium is regenerated from the salt by an electrowinning process. The lithium and the salt from the electrowinning are then reused for reduction of the next batch of oxide fuel. The process cycle has been successfully demonstrated on an engineering scale in a specially designed pyroprocessing facility. This paper discusses the applicability of lithium in molten-salt reduction processes with specific reference to our process. Results are presented from our work on actinide oxides to highlight the role of lithium and its effect on process variables in these molten-salt based reduction processes

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...

Active Vibration Reduction of the Advanced Stirling Convertor

Science.gov (United States)

Wilson, Scott D.; Metscher, Jonathan F.; Schifer, Nicholas A.

2016-01-01

Stirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint compared to the current state of the art. The Stirling Cycle Technology Development (SCTD) Project is funded by the RPS Program to developing Stirling-based subsystems, including convertors and controller maturation efforts that have resulted in high fidelity hardware like the Advanced Stirling Radioisotope Generator (ASRG), Advanced Stirling Convertor (ASC), and ASC Controller Unit (ACU). The SCTD Project also performs research to develop less mature technologies with a wide variety of objectives, including increasing temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Active vibration reduction systems (AVRS), or "balancers", have historically been developed and characterized to provide fault tolerance for generator designs that incorporate dual-opposed Stirling convertors or enable single convertor, or small RPS, missions. Balancers reduce the dynamic disturbance forces created by the power piston and displacer internal moving components of a single operating convertor to meet spacecraft requirements for induced disturbance force. To improve fault tolerance for dual-opposed configurations and enable single convertor configurations, a breadboard AVRS was implemented on the Advanced Stirling Convertor (ASC). The AVRS included a linear motor, a motor mount, and a closed-loop controller able to balance out the transmitted peak dynamic disturbance using acceleration feedback. Test objectives included quantifying power and mass penalty and reduction in transmitted force over a range of ASC

Study on the vibrational scraping of uranium product from a solid cathode of electrorefiner

Energy Technology Data Exchange (ETDEWEB)

Park, Sung Bin; Kang, Young Ho; Hwang, Sung Chan; Lee, Han Soo; Paek, Seung Woo; Ahn, Do Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-12-15

A high-throughput electrorefiner has been developed for commercialization use by enhancing the uranium recovery from the reduced metal which is produced from the oxide reduction process. It is necessary to scrap and effectively collect uranium dendrites from the surface of the solid cathode for high yield. When a steel electrode is used as the cathode in the electrorefining process, uranium is deposited and regularly stuck to the steel cathode during electrorefining. The sticking coefficient of a steel cathode is very high. In order to decrease the sticking coefficient of the steel cathode effectively, vibration mode was applied to the electrode in this study. Uranium dendrites were scraped and fell apart from the steel cathode by a vibration force. The vibrational scraping of the steel cathode was compared to the self-scraping of the graphite cathode. Effects of the applied current density and the vibration stroke on the scraping of the uranium dendrites were also investigated.

A New CMOS Posicast Pre-shaper for Vibration Reduction of CMOS Op-Amps

Science.gov (United States)

Rasoulzadeh, M.; Ghaznavi-Ghoushchi, M. B.

2010-06-01

Posicast-based control is a widely used method in vibration reduction of lightly damped oscillatory systems especially in mechanical fields. The target systems to apply Posicast method are the systems which are excited by pulse inputs. Using the Posicast idea, the input pulse is reshaped into a new pulse, which is called Posicast pulse. Applying the generated Posicast pulse reduces the undesired oscillatory manner of under-test systems. In this paper, a fully CMOS Pulse pre-shaper circuit for realization of Posicast command is proposed. Our design is based on delay-and-add approach for the incoming pulses. The delay is done via a modified Schmitt Trigger-like circuit. The adder circuit is implemented by a simple non-binary analog adder terminated by a passive element. Our proposed design has a reasonable flexibility in configuration of time delay and amplitude of the desired pulse-like shapes. The delay is controlled via the delay unit and the pre-shaped pulse's amplitudes are controlled by an analog adder unit. The overall system has 18 MOS transistors, one small capacitor, and one resistor. To verify the effectiveness of the recommended method, it is experienced on a real CMOS Op-Amp. HSPICE simulation results, on 0.25u technology, show a significant reduction on overshoot and settling time of the under-test Op-Amp. The mentioned reduction is more than 95% in overshoot and more than 60% in settling time of the system.

Experimental Study on the Vibration Control Effect of Long Elastic Sleeper Track in Subways

Directory of Open Access Journals (Sweden)

Xiaopei Cai

2018-01-01

Full Text Available The vibration effect of urban rail transit has gained attention from both academia and the industry sector. Long Elastic Sleeper Track (LEST is a new structure for vibration reduction which has recently been designed and applied to Chinese subways. However, little research has been devoted to its vibration reduction effect. In this study, field tests were conducted during peak transit hours on Beijing Subway Line 15 to examine the vibration reduction effects of the common ballastless track and LEST on both straight and curved sections. The results demonstrate that although LEST increases the wheel-rail vertical forces, rail vertical displacements, and rail accelerations to some extent, these effects do not threaten subway operational safety, and vibrations of track bed and tunnel wall are positively mitigated. LEST has an obvious vibration reduction effect at frequencies above 40 Hz. In straight track, the vibration of bottom of the tunnel wall measured in one-third octave bands is reduced by 10.52 dB, while the vibration at point on the tunnel wall at 1.5 m height is reduced by 9.60 dB. For the curved track, the vibrations at those two points are reduced by 9.35 dB and 8.44 dB, respectively. This indicates that LEST reduces vibrations slightly more for the straight track than for the curved track.

A method of noise reduction in heterodyne interferometric vibration metrology by combining auto-correlation analysis and spectral filtering

Science.gov (United States)

Hao, Hongliang; Xiao, Wen; Chen, Zonghui; Ma, Lan; Pan, Feng

2018-01-01

Heterodyne interferometric vibration metrology is a useful technique for dynamic displacement and velocity measurement as it can provide a synchronous full-field output signal. With the advent of cost effective, high-speed real-time signal processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. However, due to the coherent nature of the laser sources, the sequence of heterodyne interferogram are corrupted by a mixture of coherent speckle and incoherent additive noise, which can severely degrade the accuracy of the demodulated signal and the optical display. In this paper, a new heterodyne interferometric demodulation method by combining auto-correlation analysis and spectral filtering is described leading to an expression for the dynamic displacement and velocity of the object under test that is significantly more accurate in both the amplitude and frequency of the vibrating waveform. We present a mathematical model of the signals obtained from interferograms that contain both vibration information of the measured objects and the noise. A simulation of the signal demodulation process is presented and used to investigate the noise from the system and external factors. The experimental results show excellent agreement with measurements from a commercial Laser Doppler Velocimetry (LDV).

Model reduction and analysis of a vibrating beam microgyroscope

KAUST Repository

Ghommem, Mehdi; Nayfeh, Ali Hasan; Choura, Slim A.

2012-01-01

The present work is concerned with the nonlinear dynamic analysis of a vibrating beam microgyroscope composed of a rotating cantilever beam with a tip mass at its end. The rigid mass is coupled to two orthogonal electrodes in the drive and sense directions, which are attached to the rotating base. The microbeam is driven by an AC voltage in the drive direction, which induces vibrations in the orthogonal sense direction due to rotation about the microbeam axis. The electrode placed in the sense direction is used to measure the induced motions and extract the underlying angular speed. A reduced-order model of the gyroscope is developed using the method of multiple scales and used to examine its dynamic behavior. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Model reduction and analysis of a vibrating beam microgyroscope

KAUST Repository

Ghommem, Mehdi

2012-05-08

The present work is concerned with the nonlinear dynamic analysis of a vibrating beam microgyroscope composed of a rotating cantilever beam with a tip mass at its end. The rigid mass is coupled to two orthogonal electrodes in the drive and sense directions, which are attached to the rotating base. The microbeam is driven by an AC voltage in the drive direction, which induces vibrations in the orthogonal sense direction due to rotation about the microbeam axis. The electrode placed in the sense direction is used to measure the induced motions and extract the underlying angular speed. A reduced-order model of the gyroscope is developed using the method of multiple scales and used to examine its dynamic behavior. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Integrated cable vibration control system using wireless sensors

Science.gov (United States)

Jeong, Seunghoo; Cho, Soojin; Sim, Sung-Han

2017-04-01

As the number of long-span bridges is increasing worldwide, maintaining their structural integrity and safety become an important issue. Because the stay cable is a critical member in most long-span bridges and vulnerable to wind-induced vibrations, vibration mitigation has been of interest both in academia and practice. While active and semi-active control schemes are known to be quite effective in vibration reduction compared to the passive control, requirements for equipment including data acquisition, control devices, and power supply prevent a widespread adoption in real-world applications. This study develops an integrated system for vibration control of stay-cables using wireless sensors implementing a semi-active control. Arduino, a low-cost single board system, is employed with a MEMS digital accelerometer and a Zigbee wireless communication module to build the wireless sensor. The magneto-rheological (MR) damper is selected as a damping device, controlled by an optimal control algorithm implemented on the Arduino sensing system. The developed integrated system is tested in a laboratory environment using a cable to demonstrate the effectiveness of the proposed system on vibration reduction. The proposed system is shown to reduce the vibration of stay-cables with low operating power effectively.

Investigation of the Processing Parameters Impact on the Flexural Tool Vibrations While Drilling

Directory of Open Access Journals (Sweden)

I. I. Ivanov

2015-01-01

Full Text Available The paper considers an approach to analyze a dynamic stability of the drilling process in terms of tool flexibility. The proposed technique takes into consideration a regenerative effect leading to time delay in the dynamic system. This regenerative delay is the main source of arising dynamically unstable machining conditions. The paper describes a principle of emerging self-vibrations while cutting. It mentions the undesirable nature of transverse bending selfvibrations of tool, which cause a decreasing quality of the processed hole surface.The suggested approach consists in building a diagram of the drilling process stability for a tool model allowing only its flexural vibrations. The feature of the study is to describe tool dynamics using a finite element model based on the quadratic approximation of displacements for tool dynamics modeling. The assumption of an axial symmetry of drill geometry was discarded. The reduced model of tool was built taking into account two eigenvectors corresponding to tool bending. This model contains 2 degrees of freedom (DOF, which are, essentially, rotations of a drill tip. The technology of rigid multi-point constraints was used to connect those DOFs with solid finite element nodes. The system of delayed differential equations describing the reduced tool model dynamics was derived to estimate a dynamic stability of the drilling process. The Floquet theory is applied to build a stability diagram as a maximum multiplicator value versus a drill rotation rate. The presented diagram allows us to draw a conclusion that in the wide range of rotation frequencies transverse bending self- vibrations can be excited. The results obtained and the calculation technique may be used to choose the operation modes free from undesirable flexural self-vibrations of tool.The reported study was supported by RFBR within the framework of the research project ” mol_a”№ 14-08-31603 “Development of methods and algorithms for

Wear reduction through piezoelectrically-assisted ultrasonic lubrication

International Nuclear Information System (INIS)

Dong, Sheng; J Dapino, Marcelo

2014-01-01

Traditional lubricants are undesirable in harsh aerospace environments and certain automotive applications. Ultrasonic vibrations can be used to reduce and modulate the effective friction coefficient between two sliding surfaces. This paper investigates the relationship between friction force reduction and wear reduction in ultrasonically lubricated surfaces. A pin-on-disc tribometer is modified through the addition of a piezoelectric transducer which vibrates the pin at 22 kHz in the direction perpendicular to the rotating disc surface. Friction and wear metrics including volume loss, surface roughness, friction forces and apparent stick-slip effects are measured without and with ultrasonic vibrations at three different sliding velocities. SEM imaging and 3D profilometry are used to characterize the wear surfaces and guide model development. Over the range of speeds considered, ultrasonic vibrations reduce the effective friction force up to 62% along with a wear reduction of up to 49%. A simple cube model previously developed to quantify friction force reduction is implemented which describes wear reduction within 15% of the experimental data. (paper)

Identification, detection, and validation of vibrating structures: a signal processing approach

International Nuclear Information System (INIS)

Candy, J.V.; Lager, D.L.

1979-01-01

This report discusses the application of modern signal processing techniques to characterize parameters governing the vibrational response of a structure. Simulated response data is used to explore the feasibility of applying these techniques to various structural problems. On-line estimator/indentifiers are used to estimate structural parameters, validate designed structures, and detect structural failure when used with a detector

Active vibration isolation of a rigidly mounted turbo pump

NARCIS (Netherlands)

Basten, T.G.H.; Doppenberg, E.J.J.

2006-01-01

Manufacturers of precision equipment are constantly aiming at increased accuracy. Elimination of disturbing vibrations is therefore getting more and more important. The technical limitations of passive isolation methods require alternative strategies for vibration reduction, such as active

Theory And Working Of Noise And Vibration

International Nuclear Information System (INIS)

Jeong, Il Rok

1988-09-01

This book deals with theory of noise including physical property of noise like term and characteristic of sound, occurrence of sound, characteristic of noise pollution and main cause of occurrence of noise, technique of prevention of noise with noise reduction, construction guide for prevention of noise, and measure of interior noise. It also has the theory of vibration such as an introduction of vibration, and technology of prevention of vibration, official test method of environmental pollution, and summary of protection of the environment.

Experimental studies of processes with vibrationally excited hydrogen molecules that are important for tokamak edge plasma

International Nuclear Information System (INIS)

Cadez, I.; Markelj, S.; Rupnik, Z.; Pelicon, P.

2006-01-01

We are currently conducting a series of different laboratory experimental studies of processes involving vibrationally excited hydrogen molecules that are relevant to fusion edge plasma. A general overview of our activities is presented together with results of studies of hydrogen recombination on surfaces. This includes vibrational spectroscopy of molecules formed by recombination on metal surfaces exposed to the partially dissociated hydrogen gas and recombination after hydrogen permeation through metal membrane. The goal of these studies is to provide numerical parameters needed for edge plasma modelling and better understanding of plasma wall interaction processes. (author)

Simulation of Vibrations in Real Time Plane Milling with Spindle Speed Correction

Directory of Open Access Journals (Sweden)

I. I. Ivanov

2017-01-01

forces, and geometrical models of cutting edges and work-piece surface.  The model is used to study an impact of described control system on the milling process dynamics. Simulations were performed for different values of rotation frequency, and two cases were considered: without and with control. Analysis of the simulations showed that the developed control system provides considerable reduction of vibration amplitudes when milling.

Determination of reduction yield of lithium metal reduction process

International Nuclear Information System (INIS)

Choi, In Kyu; Cho, Young Hwan; Kim, Taek Jin; Jee, Kwang Young

2004-01-01

Metal reduction of spent oxide fuel is the first step for the effective storage of spent fuel in Korea as well as transmutation purpose of long-lived radio-nuclides. During the reduction of uranium oxide by lithium metal to uranium metal, lithium oxide is stoichiometrically produced. By determining the concentration of lithium oxide in lithium chloride, we can estimate that how much uranium oxide is converted to uranium metal. Previous method to determine the lithium oxide concentration in lithium chloride is tedious and timing consuming. This paper describe the on-line monitoring method of lithium oxide during the reduction process

Vibration-based monitoring and diagnostics using compressive sensing

Science.gov (United States)

Ganesan, Vaahini; Das, Tuhin; Rahnavard, Nazanin; Kauffman, Jeffrey L.

2017-04-01

Vibration data from mechanical systems carry important information that is useful for characterization and diagnosis. Standard approaches rely on continually streaming data at a fixed sampling frequency. For applications involving continuous monitoring, such as Structural Health Monitoring (SHM), such approaches result in high volume data and rely on sensors being powered for prolonged durations. Furthermore, for spatial resolution, structures are instrumented with a large array of sensors. This paper shows that both volume of data and number of sensors can be reduced significantly by applying Compressive Sensing (CS) in vibration monitoring applications. The reduction is achieved by using random sampling and capitalizing on the sparsity of vibration signals in the frequency domain. Preliminary experimental results validating CS-based frequency recovery are also provided. By exploiting the sparsity of mode shapes, CS can also enable efficient spatial reconstruction using fewer spatially distributed sensors. CS can thereby reduce the cost and power requirement of sensing as well as streamline data storage and processing in monitoring applications. In well-instrumented structures, CS can enable continued monitoring in case of sensor or computational failures.

Advanced digital signal processing and noise reduction

CERN Document Server

Vaseghi, Saeed V

2008-01-01

Digital signal processing plays a central role in the development of modern communication and information processing systems. The theory and application of signal processing is concerned with the identification, modelling and utilisation of patterns and structures in a signal process. The observation signals are often distorted, incomplete and noisy and therefore noise reduction, the removal of channel distortion, and replacement of lost samples are important parts of a signal processing system. The fourth edition of Advanced Digital Signal Processing and Noise Reduction updates an

The Vibration Sensors Optimum Mounting Analysis at Planetary Reduction Gearmotor Vibration Diagnostics

OpenAIRE

Ļitvinovs, D

2008-01-01

Due to the specific mechanical peculiarities, planetary reduction gearmotors were and remain the most progressive types of reduction gearboxes for industry application. Compactness, small specific gravity and, simultaneously, possibility to pass the increased loadings – here what planetary reduction gearmotors are attractive for developers and customers. Because of planetary reduction gearmotors increased amount applying in industry, increases the requirements in their diagnostics. For this p...

Vibration behavior optimization of planetary gear sets

Directory of Open Access Journals (Sweden)

Farshad Shakeri Aski

2014-12-01

Full Text Available This paper presents a global optimization method focused on planetary gear vibration reduction by means of tip relief profile modifications. A nonlinear dynamic model is used to study the vibration behavior. In order to investigate the optimal radius and amplitude, Brute Force method optimization is used. One approach in optimization is straightforward and requires considerable computation power: brute force methods try to calculate all possible solutions and decide afterwards which one is the best. Results show the influence of optimal profile on planetary gear vibrations.

Semi-active control of helicopter vibration using controllable stiffness and damping devices

Science.gov (United States)

Anusonti-Inthra, Phuriwat

Semi-active concepts for helicopter vibration reduction are developed and evaluated in this dissertation. Semi-active devices, controllable stiffness devices or controllable orifice dampers, are introduced; (i) in the blade root region (rotor-based concept) and (ii) between the rotor and the fuselage as semi-active isolators (in the non-rotating frame). Corresponding semi-active controllers for helicopter vibration reduction are also developed. The effectiveness of the rotor-based semi-active vibration reduction concept (using stiffness and damping variation) is demonstrated for a 4-bladed hingeless rotor helicopter in moderate- to high-speed forward flight. A sensitivity study shows that the stiffness variation of root element can reduce hub vibrations when proper amplitude and phase are used. Furthermore, the optimal semi-active control scheme can determine the combination of stiffness variations that produce significant vibration reduction in all components of vibratory hub loads simultaneously. It is demonstrated that desired cyclic variations in properties of the blade root region can be practically achieved using discrete controllable stiffness devices and controllable dampers, especially in the flap and lag directions. These discrete controllable devices can produce 35--50% reduction in a composite vibration index representing all components of vibratory hub loads. No detrimental increases are observed in the lower harmonics of blade loads and blade response (which contribute to the dynamic stresses) and controllable device internal loads, when the optimal stiffness and damping variations are introduced. The effectiveness of optimal stiffness and damping variations in reducing hub vibration is retained over a range of cruise speeds and for variations in fundamental rotor properties. The effectiveness of the semi-active isolator is demonstrated for a simplified single degree of freedom system representing the semi-active isolation system. The rotor

Statistical Analysis of Deep Drilling Process Conditions Using Vibrations and Force Signals

Directory of Open Access Journals (Sweden)

Syafiq Hazwan

2016-01-01

Full Text Available Cooling systems is a key point for hot forming process of Ultra High Strength Steels (UHSS. Normally, cooling systems is made using deep drilling technique. Although deep twist drill is better than other drilling techniques in term of higher productivity however its main problem is premature tool breakage, which affects the production quality. In this paper, analysis of deep twist drill process parameters such as cutting speed, feed rate and depth of cut by using statistical analysis to identify the tool condition is presented. The comparisons between different two tool geometries are also studied. Measured data from vibrations and force sensors are being analyzed through several statistical parameters such as root mean square (RMS, mean, kurtosis, standard deviation and skewness. Result found that kurtosis and skewness value are the most appropriate parameters to represent the deep twist drill tool conditions behaviors from vibrations and forces data. The condition of the deep twist drill process been classified according to good, blunt and fracture. It also found that the different tool geometry parameters affect the performance of the tool drill. It believe the results of this study are useful in determining the suitable analysis method to be used for developing online tool condition monitoring system to identify the tertiary tool life stage and helps to avoid mature of tool fracture during drilling process.

The Analysis and Suppression of the spike noise in vibrator record

Science.gov (United States)

Jia, H.; Jiang, T.; Xu, X.; Ge, L.; Lin, J.; Yang, Z.

2013-12-01

During the seismic exploration with vibrator, seismic recording systems have often been affected by random spike noise in the background, which leads to strong data distortions as a result of the cross-correlation processing of the vibrator method. Partial or total loss of the desired seismic information is possible if no automatic spike reduction is available in the field prior to correlation of the field record. Generally speaking, original record of vibrator is uncorrelated data, in which the signal is non-wavelet form. In order to obtain the seismic record similar to explosive source, the signal of uncorrelated data needs to use the correlation algorithm to compress into wavelet form. The correlation process results in that the interference of spike in correlated data is not only being suppressed, but also being expanded. So the spike noise suppression of vibrator is indispensable. According to numerical simulation results, the effect of spike in the vibrator record is mainly affected by the amplitude and proportional points in the uncorrelated record. When the spike noise ratio in uncorrelated record reaches 1.5% and the average amplitude exceeds 200, it will make the SNR(signal-to-noise ratio) of the correlated record lower than 0dB, so that it is difficult to separate the signal. While the amplitude and ratio is determined by the intensity of background noise. Therefore, when the noise level is strong, in order to improve SNR of the seismic data, the uncorrelated record of vibrator need to take necessary steps to suppress spike noise. For the sake of reducing the influence of the spike noise, we need to make the detection and suppression of spike noise process for the uncorrelated record. Because vibrator works by inputting sweep signal into the underground long time, ideally, the peak and valley values of each trace have little change. On the basis of the peak and valley values, we can get a reference amplitude value. Then the spike can be detected and

[Treatment of acrylate wastewater by electrocatalytic reduction process].

Science.gov (United States)

Yu, Li-Na; Song, Yu-Dong; Zhou, Yue-Xi; Zhu, Shu-Quan; Zheng, Sheng-Zhi; Ll, Si-Min

2011-10-01

High-concentration acrylate wastewater was treated by an electrocatalytic reduction process. The effects of the cation exchange membrane (CEM) and cathode materials on acrylate reduction were investigated. It indicated that the acrylate could be reduced to propionate acid efficiently by the electrocatalytic reduction process. The addition of CEM to separator with the cathode and anode could significantly improve current efficiency. The cathode materials had significant effect on the reduction of acrylate. The current efficiency by Pd/Nickel foam, was greater than 90%, while those by nickel foam, the carbon fibers and the stainless steel decreased successively. Toxicity of the wastewater decreased considerably and methane production rate in the biochemical methane potential (BMP) test increased greatly after the electrocatalytic reduction process.

Model reduction for the dynamics and control of large structural systems via neutral network processing direct numerical optimization

Science.gov (United States)

Becus, Georges A.; Chan, Alistair K.

1993-01-01

Three neural network processing approaches in a direct numerical optimization model reduction scheme are proposed and investigated. Large structural systems, such as large space structures, offer new challenges to both structural dynamicists and control engineers. One such challenge is that of dimensionality. Indeed these distributed parameter systems can be modeled either by infinite dimensional mathematical models (typically partial differential equations) or by high dimensional discrete models (typically finite element models) often exhibiting thousands of vibrational modes usually closely spaced and with little, if any, damping. Clearly, some form of model reduction is in order, especially for the control engineer who can actively control but a few of the modes using system identification based on a limited number of sensors. Inasmuch as the amount of 'control spillover' (in which the control inputs excite the neglected dynamics) and/or 'observation spillover' (where neglected dynamics affect system identification) is to a large extent determined by the choice of particular reduced model (RM), the way in which this model reduction is carried out is often critical.

Controlling flexible rotor vibrations using parametric excitation

Energy Technology Data Exchange (ETDEWEB)

Atepor, L, E-mail: katepor@yahoo.co [Department of Mechanical Engineering, University of Glasgow, G12 8QQ (United Kingdom)

2009-08-01

This paper presents both theoretical and experimental studies of an active vibration controller for vibration in a flexible rotor system. The paper shows that the vibration amplitude can be modified by introducing an axial parametric excitation. The perturbation method of multiple scales is used to solve the equations of motion. The steady-state responses, with and without the parametric excitation terms, is investigated. An experimental test machine uses a piezoelectric exciter mounted on the end of the shaft. The results show a reduction in the rotor response amplitude under principal parametric resonance, and some good correlation between theory and experiment.

Condition Monitoring of a Process Filter Applying Wireless Vibration Analysis

Directory of Open Access Journals (Sweden)

Pekka KOSKELA

2011-05-01

Full Text Available This paper presents a novel wireless vibration-based method for monitoring the degree of feed filter clogging. In process industry, these filters are applied to prevent impurities entering the process. During operation, the filters gradually become clogged, decreasing the feed flow and, in the worst case, preventing it. The cleaning of the filter should therefore be carried out predictively in order to avoid equipment damage and unnecessary process downtime. The degree of clogging is estimated by first calculating the time domain indices from low frequency accelerometer samples and then taking the median of the processed values. Nine different statistical quantities are compared based on the estimation accuracy and criteria for operating in resource-constrained environments with particular focus on energy efficiency. The initial results show that the method is able to detect the degree of clogging, and the approach may be applicable to filter clogging monitoring.

Method for qualification of cementation processes and its application to a vibration mixer

International Nuclear Information System (INIS)

Vicente, R.; Rzyski, B.M.; Suarez, A.A.

1987-01-01

In this paper the definition of homogeneneity is discussed and methods to measure the 'degree of heterogeneity' of waste forms are proposed. These measurements are important as aids for mixing process qualification, and as tools in quality assurance procedures and in the development of waste management standards. Homogeneity is a basic quality requirement for waste forms to be accepted in final sites. It do not depend on the matrix immmobilization, rather it is one mean for qualification of the immobilization process. The proposed methods were applied to a vibration assisted mixing process and has proved to an useful mean to judge process improvements. There are many conceivable methods to evaluate homogeneity of waste forms. Some were selected as screening tests aiming at quickly reaching a promising set of process variables. Others were selected to evaluate the degree of excellence of the process in respect to product quality. These envisaged methods were: visual inspection, the use of cement dye as tracer, scanning of radioactive tracers, and measurements of variations of density, water absorption, porosity and mechanical strength across the waste form sample. The process variables were: waste-cement and water-cement ratios, mixer geometry, mixing time and vibration intensity. Some of the apparatus details were change during the experimental work in order to improve product quality. Experimental methods and results statistically analysed and compared with data obtained from samples prepared with a planetary paddle mixer, which were adopted as the homogeneity standard. (Author) [pt

Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

Science.gov (United States)

Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

2018-01-01

Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

Simulation Study of Electronic Damping of Microphonic Vibrations in Superconducting Cavities

International Nuclear Information System (INIS)

Alicia Hofler; Jean Delayen

2005-01-01

Electronic damping of microphonic vibrations in superconducting rf cavities involves an active modulation of the cavity field amplitude in order to induce ponderomotive forces that counteract the effect of ambient vibrations on the cavity frequency. In lightly beam loaded cavities, a reduction of the microphonics-induced frequency excursions leads directly to a reduction of the rf power required for phase and amplitude stabilization. Jefferson Lab is investigating such an electronic damping scheme that could be applied to the JLab 12 GeV upgrade, the RIA driver, and possibly to energy-recovering superconducting linacs. This paper discusses a model and presents simulation results for electronic damping of microphonic vibrations

Uranium manufacturing process employing the electrolytic reduction method

International Nuclear Information System (INIS)

Oda, Yoshio; Kazuhare, Manabu; Morimoto, Takeshi.

1986-01-01

The present invention related to a uranium manufacturing process that employs the electrolytic reduction method, but particularly to a uranium manufacturing process that employs an electrolytic reduction method requiring low voltage. The process, in which uranium is obtained by means of the electrolytic method and with uranyl acid as the raw material, is prior art

Vibration isolation of a building against earthquake, airplane crash and blast

International Nuclear Information System (INIS)

Mischke, J.; Hilpert, H.J.; Henkel, F.O.

1986-01-01

The influence of three different support concepts on the vibration responses of a building to the load cases earthquake, airplane crash and blast is numerically investigated. Compared are the three concepts: the standard version of a double shell structure with a combined base for inner and outer building without isolation system; the same building with isolation system between foundation slab and soil, as vibration isolation known so far; and as a third concept a double shell structure with completely separated inner and outer building, where the isolation system is placed between the two parts of the building. The results show that, compared to the standard concept, the third concept leads to a nearly complete isolation of shock-induced vibrations, and to a reduction of the vibrations caused by an earthquake, comparable to the reduction in the isolation concept known so far. (orig.)

Piezoelectric shunt damping of a circular saw blade with autonomous power supply for noise and vibration reduction

Science.gov (United States)

Pohl, Martin; Rose, Michael

2016-01-01

Circular saws are widespread tools for machining metal, wood or even ceramics. Due to the thin blade and excitation by the workpiece contact of the cutting edges, circular saws are prone to vibration and intense noise emission. Damping the blade will lower the hearing protection requirements of the users and possibly increase precision. Therefore a new damping concept for circular saw blades is presented in this paper. It is based on negative capacitance shunted piezoelectric transducers which are applied to the saw blade core. The required energy for the electronics is harvested from the rotation by a generator, so that no change of the machine tool is required. All components are integrated into an autonomous saw tool. Finally, the system is experimentally investigated without rotation, in idling and in cutting condition in a circular saw test stand in the Institute for Machine Tools and Production Engineering (IWF) at TU Braunschweig. The experimental investigation shows a good reduction of the vibration amplitude over a wide frequency range in the non-rotating condition. When rotating, the damping effect is lower and limited to some narrow frequency bands. The proposed reason for the reduced damping effect in rotating condition consists in the saturation of the electronic circuits due to the limited supply voltage capabilities.

Selection of site specific vibration equation by using analytic hierarchy process in a quarry

Energy Technology Data Exchange (ETDEWEB)

Kalayci, Ulku, E-mail: ukalayci@istanbul.edu.tr; Ozer, Umit, E-mail: uozer@istanbul.edu.tr

2016-01-15

This paper presents a new approach for the selection of the most accurate SSVA (Site Specific Vibration Attenuation) equation for blasting processes in a quarry located near settlements in Istanbul, Turkey. In this context, the SSVA equations obtained from the same study area in the literature were considered in terms of distance between the shot points and buildings and the amount of explosive charge. In this purpose, 11 different SSVA equations obtained from the study area in the past 12 years, forecasting capabilities according to designated new conditions, using 102 vibration records as test data obtained from the study area was investigated. In this study, AHP (Analytic Hierarchy Process) was selected as an analysis method in order to determine the most accurate equation among 11 SSAV equations, and the parameters such as year, distance, charge, and r{sup 2} of the equations were used as criteria for AHP. Finally, the most appropriate equation was selected among the existing ones, and the process of selecting according to different target criteria was presented. Furthermore, it was noted that the forecasting results of the selected equation is more accurate than that formed using the test results. - Highlights: • The optimum Site Specific Vibration Attenuation equation for blasting in a quarry located near settlements was determined. • It is indicated that SSVA equations changing over the years don’t give always accurate estimates at changing conditions. • Selection of the blast induced SSVA equation was made using AHP. • Equation selection method was highlighted based on parameters such as charge, distance, and quarry geometry changes (year).

Selection of site specific vibration equation by using analytic hierarchy process in a quarry

International Nuclear Information System (INIS)

Kalayci, Ulku; Ozer, Umit

2016-01-01

This paper presents a new approach for the selection of the most accurate SSVA (Site Specific Vibration Attenuation) equation for blasting processes in a quarry located near settlements in Istanbul, Turkey. In this context, the SSVA equations obtained from the same study area in the literature were considered in terms of distance between the shot points and buildings and the amount of explosive charge. In this purpose, 11 different SSVA equations obtained from the study area in the past 12 years, forecasting capabilities according to designated new conditions, using 102 vibration records as test data obtained from the study area was investigated. In this study, AHP (Analytic Hierarchy Process) was selected as an analysis method in order to determine the most accurate equation among 11 SSAV equations, and the parameters such as year, distance, charge, and r"2 of the equations were used as criteria for AHP. Finally, the most appropriate equation was selected among the existing ones, and the process of selecting according to different target criteria was presented. Furthermore, it was noted that the forecasting results of the selected equation is more accurate than that formed using the test results. - Highlights: • The optimum Site Specific Vibration Attenuation equation for blasting in a quarry located near settlements was determined. • It is indicated that SSVA equations changing over the years don’t give always accurate estimates at changing conditions. • Selection of the blast induced SSVA equation was made using AHP. • Equation selection method was highlighted based on parameters such as charge, distance, and quarry geometry changes (year).

Bandshapes in vibrational spectroscopy

International Nuclear Information System (INIS)

Dijkman, F.G.

1978-01-01

A detailed account is given of the development of modern bandshape theories since 1965. An investigation into the relative contributions of statistical irreversible relaxation processes is described, for a series of molecules in which gradually the length of one molecular axis is increased. An investigation into the theoretical and experimental investigation of the broadening brought about by the effect of fluctuating intermolecular potentials on the vibrational frequency is also described. The effect of an intermolecular perturbative potential on anharmonic and Morse oscillators is discussed and the results are presented of a computation on the broadening of the vibrational band of some diatomic molecules in a rigid lattice type solvent. The broadening of the OH-stretching vibration in a number of aliphatic alcohols, the vibrational bandshapes of the acetylenic C-H stretching vibration and of the symmetric methyl stretching vibration are investigated. (Auth./ C.F.)

Evaluation of vibration and vibration fatigue life for small bore pipe in nuclear power plants

International Nuclear Information System (INIS)

Wang Zhaoxi; Xue Fei; Gong Mingxiang; Ti Wenxin; Lin Lei; Liu Peng

2011-01-01

The assessment method of the steady state vibration and vibration fatigue life of the small bore pipe in the supporting system of the nuclear power plants is proposed according to the ASME-OM3 and EDF evaluation methods. The GGR supporting pipe system vibration is evaluated with this method. The evaluation process includes the filtration of inborn sensitivity, visual inspection, vibration tests, allowable vibration effective velocity calculation and vibration stress calculation. With the allowable vibration effective velocity calculated and the vibration velocity calculated according to the acceleration data tested, the filtrations are performed. The vibration stress at the welding coat is calculated with the spectrum method and compared with the allowable value. The response of the stress is calculated with the transient dynamic method, with which the fatigue life is evaluated with the Miners linear accumulation model. The vibration stress calculated with the spectrum method exceeds the allowable value, while the fatigue life calculated from the transient dynamic method is larger than the designed life with a big safety margin. (authors)

Automatic crack detection method for loaded coal in vibration failure process.

Directory of Open Access Journals (Sweden)

Chengwu Li

Full Text Available In the coal mining process, the destabilization of loaded coal mass is a prerequisite for coal and rock dynamic disaster, and surface cracks of the coal and rock mass are important indicators, reflecting the current state of the coal body. The detection of surface cracks in the coal body plays an important role in coal mine safety monitoring. In this paper, a method for detecting the surface cracks of loaded coal by a vibration failure process is proposed based on the characteristics of the surface cracks of coal and support vector machine (SVM. A large number of cracked images are obtained by establishing a vibration-induced failure test system and industrial camera. Histogram equalization and a hysteresis threshold algorithm were used to reduce the noise and emphasize the crack; then, 600 images and regions, including cracks and non-cracks, were manually labelled. In the crack feature extraction stage, eight features of the cracks are extracted to distinguish cracks from other objects. Finally, a crack identification model with an accuracy over 95% was trained by inputting the labelled sample images into the SVM classifier. The experimental results show that the proposed algorithm has a higher accuracy than the conventional algorithm and can effectively identify cracks on the surface of the coal and rock mass automatically.

«Green» Energy Harvesting by Means of Piezoflexogeneration from Vibration or Similar Processes

Directory of Open Access Journals (Sweden)

Timofey G. Lupeiko

2013-01-01

Full Text Available The piezoelectric systems of electric energy harvesting with an adaptive low-frequency resonance are developed. These systems allowed to obtain electricity from low-frequency vibration. The availability of their application for adaptation to other periodic processes including pedestrians and vehicles movement is shown.

Crack identification and evolution law in the vibration failure process of loaded coal

Science.gov (United States)

Li, Chengwu; Ai, Dihao; Sun, Xiaoyuan; Xie, Beijing

2017-08-01

To study the characteristics of coal cracks produced in the vibration failure process, we set up a static load and static and dynamic combination load failure test simulation system, prepared with different particle size, formation pressure, and firmness coefficient coal samples. Through static load damage testing of coal samples and then dynamic load (vibration exciter) and static (jack) combination destructive testing, the crack images of coal samples under the load condition were obtained. Combined with digital image processing technology, an algorithm of crack identification with high precision and in real-time is proposed. With the crack features of the coal samples under different load conditions as the research object, we analyzed the distribution of cracks on the surface of the coal samples and the factors influencing crack evolution using the proposed algorithm and a high-resolution industrial camera. Experimental results showed that the major portion of the crack after excitation is located in the rear of the coal sample where the vibration exciter cannot act. Under the same disturbance conditions, crack size and particle size exhibit a positive correlation, while crack size and formation pressure exhibit a negative correlation. Soft coal is more likely to lead to crack evolution than hard coal, and more easily causes instability failure. The experimental results and crack identification algorithm provide a solid basis for the prevention and control of instability and failure of coal and rock mass, and they are helpful in improving the monitoring method of coal and rock dynamic disasters.

Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

Science.gov (United States)

Platt, Michael; Jagodnik, John

2011-01-01

A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

Dimensional Reduction and Hadronic Processes

International Nuclear Information System (INIS)

Signer, Adrian; Stoeckinger, Dominik

2008-01-01

We consider the application of regularization by dimensional reduction to NLO corrections of hadronic processes. The general collinear singularity structure is discussed, the origin of the regularization-scheme dependence is identified and transition rules to other regularization schemes are derived.

On the neutron noise diagnostics of pressurized water reactor control rod vibrations. 1. periodic vibrations

International Nuclear Information System (INIS)

Pazsit, I.; Glockler, O.

1983-01-01

Based on the theory of neutron noise arising from the vibration of a localized absorber, the possibility of rod vibration diagnostics is investigated. It is found that noise source characteristics, namely rod position and vibration trajectory and spectra, can be unfolded from measured neutron noise signals. For the localization process, the first and more difficult part of the diagnostics, a procedure is suggested whose novelty is that it is applicable in case of arbitrary vibration trajectories. Applicability of the method is investigated in numerical experiments where effects of background noise are also accounted for

Low Cost Digital Vibration Meter.

Science.gov (United States)

Payne, W Vance; Geist, Jon

2007-01-01

This report describes the development of a low cost, digital Micro Electro Mechanical System (MEMS) vibration meter that reports an approximation to the RMS acceleration of the vibration to which the vibration meter is subjected. The major mechanical element of this vibration meter is a cantilever beam, which is on the order of 500 µm in length, with a piezoresistor deposited at its base. Vibration of the device in the plane perpendicular to the cantilever beam causes it to bend, which produces a measurable change in the resistance of a piezoresistor. These changes in resistance along with a unique signal-processing scheme are used to determine an approximation to the RMS acceleration sensed by the device.

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.

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.

Catalytic and inhibitory effects of thechnetium on reduction processes

International Nuclear Information System (INIS)

Grases, F.; Genestar, C.; March, J.G.; March, P.

1986-01-01

Interactions between technetium and some anthraquinones and tartrazin in the presence of tin(II) are described. It was found that whereas the reductive process between Sn(II) and 1-amino-4-hydroxyanthraquinone is catalyzed by technetium, the reduction of tartrazin is inhibited by this element. Study of such process seems to indicate that the catalytic effect of technetium on the reduction processes is due to Tc(V) action whereas the inhibitory effect is due to the Tc(IV) species. (author)

Hydrogen Plasma Processing of Iron Ore

Science.gov (United States)

Sabat, Kali Charan; Murphy, Anthony B.

2017-06-01

Iron is currently produced by carbothermic reduction of oxide ores. This is a multiple-stage process that requires large-scale equipment and high capital investment, and produces large amounts of CO2. An alternative to carbothermic reduction is reduction using a hydrogen plasma, which comprises vibrationally excited molecular, atomic, and ionic states of hydrogen, all of which can reduce iron oxides, even at low temperatures. Besides the thermodynamic and kinetic advantages of a hydrogen plasma, the byproduct of the reaction is water, which does not pose any environmental problems. A review of the theory and practice of iron ore reduction using a hydrogen plasma is presented. The thermodynamic and kinetic aspects are considered, with molecular, atomic and ionic hydrogen considered separately. The importance of vibrationally excited hydrogen molecules in overcoming the activation energy barriers, and in transferring energy to the iron oxide, is emphasized. Both thermal and nonthermal plasmas are considered. The thermophysical properties of hydrogen and argon-hydrogen plasmas are discussed, and their influence on the constriction and flow in the of arc plasmas is considered. The published R&D on hydrogen plasma reduction of iron oxide is reviewed, with both the reduction of molten iron ore and in-flight reduction of iron ore particles being considered. Finally, the technical and economic feasibility of the process are discussed. It is shown that hydrogen plasma processing requires less energy than carbothermic reduction, mainly because pelletization, sintering, and cokemaking are not required. Moreover, the formation of the greenhouse gas CO2 as a byproduct is avoided. In-flight reduction has the potential for a throughput at least equivalent to the blast furnace process. It is concluded that hydrogen plasma reduction of iron ore is a potentially attractive alternative to standard methods.

Model Predictive Vibration Control Efficient Constrained MPC Vibration Control for Lightly Damped Mechanical Structures

CERN Document Server

Takács, Gergely

2012-01-01

Real-time model predictive controller (MPC) implementation in active vibration control (AVC) is often rendered difficult by fast sampling speeds and extensive actuator-deformation asymmetry. If the control of lightly damped mechanical structures is assumed, the region of attraction containing the set of allowable initial conditions requires a large prediction horizon, making the already computationally demanding on-line process even more complex. Model Predictive Vibration Control provides insight into the predictive control of lightly damped vibrating structures by exploring computationally efficient algorithms which are capable of low frequency vibration control with guaranteed stability and constraint feasibility. In addition to a theoretical primer on active vibration damping and model predictive control, Model Predictive Vibration Control provides a guide through the necessary steps in understanding the founding ideas of predictive control applied in AVC such as: ·         the implementation of ...

MR Damper Controlled Vibration Absorber for Enhanced Mitigation of Harmonic Vibrations

Directory of Open Access Journals (Sweden)

Felix Weber

2016-12-01

Full Text Available This paper describes a semi-active vibration absorber (SVA concept based on a real-time controlled magnetorheological damper (MR-SVA for the enhanced mitigation of structural vibrations due to harmonic disturbing forces. The force of the MR damper is controlled in real-time to generate the frequency and damping controls according to the behaviour of the undamped vibration absorber for the actual frequency of vibration. As stiffness and damping emulations in semi-active actuators are coupled quantities the control is formulated to prioritize the frequency control by the controlled stiffness. The control algorithm is augmented by a stiffness correction method ensuring precise frequency control when the desired control force is constrained by the semi-active restriction and residual force of the MR damper. The force tracking task is solved by a model-based feed forward with feedback correction. The MR-SVA is numerically and experimentally validated for the primary structure with nominal eigenfrequency and when de-tuning of −10%, −5%, +5% and +10% is present. Both validations demonstrate that the MR-SVA improves the vibration reduction in the primary structure by up to 55% compared to the passive tuned mass damper (TMD. Furthermore, it is shown that the MR-SVA with only 80% of tuned mass leads to approximately the same enhanced performance while the associated increased relative motion amplitude of the tuned mass is more than compensated be the reduced dimensions of the mass. Therefore, the MR-SVA is an appropriate solution for the mitigation of tall buildings where the pendulum mass can be up to several thousands of metric tonnes and space for the pendulum damper is limited.

Signal Processing Methods for Removing the Effects of Whole Body Vibration upon Speech

Science.gov (United States)

Bitner, Rachel M.; Begault, Durand R.

2014-01-01

Humans may be exposed to whole-body vibration in environments where clear speech communications are crucial, particularly during the launch phases of space flight and in high-performance aircraft. Prior research has shown that high levels of vibration cause a decrease in speech intelligibility. However, the effects of whole-body vibration upon speech are not well understood, and no attempt has been made to restore speech distorted by whole-body vibration. In this paper, a model for speech under whole-body vibration is proposed and a method to remove its effect is described. The method described reduces the perceptual effects of vibration, yields higher ASR accuracy scores, and may significantly improve intelligibility. Possible applications include incorporation within communication systems to improve radio-communication systems in environments such a spaceflight, aviation, or off-road vehicle operations.

Experimental Research on Vibrations of Double Harmonic Gear Transmission

Directory of Open Access Journals (Sweden)

Sava Ianici

2017-11-01

Full Text Available Gears transmission can be important sources of vibration in the mechanical system structures and can have a significant share in the overall vibration level. The current trend of significant increase in powers and speeds transmitted by modern mechanical systems, along with the size reduction, may cause a worsening of the behaviour of transmissions with gears in terms of vibration, especially when the optimization criteria were not respected in the design, execution and installation phase. This paper presents a study of vibrations that occur in a double harmonic gear transmission (DHGT, based on experimental research. The experimental researches revealed that in a double harmonic gear transmission the vibrations are initiated and develop in the multipara harmonics engagement of the teeth and in the kinematic couplings materialized between the wave generator and the flexible toothed wheel. These vibrations are later transmitted by means of the shafts and bearings to the transmission housing, respectively, through the walls of it, propagating in the air.

Mitigation of Ground Vibration by Double Sheet-pile Walls

DEFF Research Database (Denmark)

Andersen, Lars; Frigaard, Peter; Augustesen, Anders

2008-01-01

Open trenches are an effective means of vibration mitigation, but they cannot be established in practice. When the trenches are covered by a concrete pavement, part of the efficiency may be lost. However, the present analysis indicates that barriers of this kind may still lead to a significant re...... reduction of the horizontal and vertical vibrations caused by traffic at a nearby road or railway....

Design and test on vibration reduction for knife driving device of combine harvester%联合收获机切割器驱动装置减振设计与试验

Institute of Scientific and Technical Information of China (English)

王志明; 马广; 吕彭民; 陈霓

2014-01-01

Summary In the knife driving system of combine harvester,a slider-crank mechanism with a simple structure is used for driving the cutter bar.A low-cost balance mass is generally used in this mechanism to offset the unbalanced force for vibration reduction.The vibration characteristics of the knife driving system should be clarified in order to develop a method to reduce the vibration.Furthermore,it is necessary to develop a design theory of the knife driving system of combine harvesters in order to derive the control parameters of the balance weights used for vibration reduction. The mechanical model of the knife driving device that is equipped with a slider-crank mechanism was constructed in order to derive the control parameters of the balance weights,such as the mass and the location of the balance mass.The simulation conditions of the model,which reflect the condition of the actual combine harvester, are listed.The angular velocity was equivalent to the rotation number of the crank wheel and was around 73 rad/s (700 r/min)in the clockwise direction.Vibration experiment was done with the type 4LZS-1.8 combine harvester. The vibration acceleration was measured using the preprocessing and cutting device of the actual combine harvester (the divider and conveying unit did not work;only the knife driving system worked).The interval time in calculation was set to 1 ms according to the sampling time of the measurement of the acceleration.The simulated inertia force was compared with measured acceleration in time series in order to evaluate the vibration model of the knife driving system.In the state without a balance mass,the simulation could express the vibration of the knife driving system well by comparing it with the measured acceleration.Consequently,this mechanical model could express the vibration characteristics of the knife driving system.The root mean square (RMS) value of the inertia force was simulated in the state with the balance mass in order to examine

Corrosion and wear behavior of Ni60CuMoW coatings fabricated by combination of laser cladding and mechanical vibration processing

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongxi, E-mail: piiiliuhx@sina.com [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Xu, Qian [Faculty of Adult Education, Kunming University of Science and Technology, Kunming 650051 (China); Wang, Chuanqi; Zhang, Xiaowei [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2015-02-05

Highlights: • Ni60CuMoW coatings were fabricated by mechanical vibration assisted laser cladding hybrid process. • The maximum micro-hardness of the coating with mechanical vibration increases by 16%. • The mass loss and friction coefficient of the coating decreases by 17% and 16%, respectively. • The E{sub corr} positive shifts 1134.9 mV and i{sub corr} decreases by nearly one order of magnitude. • The ideal vibration parameters is vibration frequency 200 Hz and vibration amplitude 140 μm. - Abstract: Ni60CuMoW composite coatings were fabricated on 45 medium carbon steel using mechanical vibration assisted laser cladding surface modification processing. The microstructure, element distribution, phase composition, microhardness, wear and corrosion resistance of cladding coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), hardness tester, friction and wear apparatus and electrochemical workstation. The results indicate that the microstructure of M{sub 23}C{sub 6} (Cr{sub 23}C{sub 6} or (Fe, Ni){sub 23}C{sub 6}) carbide dispersion strengthening phase is uniformly distributed in eutectic (Ni, Fe) phase. The in-situ BCr and MoC compounds distribute in lamellar structure Fe{sub 3}B and dendrite Fe{sub 3}Ni{sub 3}Si, and some new W{sub 2}C phases also generated in Ni60CuMoW coating. In addition, the coarse dendrite has been replaced by some fine grain structure at the bonding interface. The fine grain hard phase makes the average microhardness of cladding coating increase from 720 to 835 HV{sub 0.5}. Under the condition of 200 Hz mechanical vibration frequency, the wear mass loss and friction coefficient of Ni60CuMoW coating are 7.6 mg and 0.068, 17% and 16% lower than the coating without mechanical vibration, respectively. The corrosion potential of cladding coating with mechanical vibration increases by 1134.9 mV and the corrosion current density decreases by nearly one order of

Vibrationally coupled electron transport through single-molecule junctions

Energy Technology Data Exchange (ETDEWEB)

Haertle, Rainer

2012-04-26

Single-molecule junctions are among the smallest electric circuits. They consist of a molecule that is bound to a left and a right electrode. With such a molecular nanocontact, the flow of electrical currents through a single molecule can be studied and controlled. Experiments on single-molecule junctions show that a single molecule carries electrical currents that can even be in the microampere regime. Thereby, a number of transport phenomena have been observed, such as, for example, diode- or transistor-like behavior, negative differential resistance and conductance switching. An objective of this field, which is commonly referred to as molecular electronics, is to relate these transport phenomena to the properties of the molecule in the contact. To this end, theoretical model calculations are employed, which facilitate an understanding of the underlying transport processes and mechanisms. Thereby, one has to take into account that molecules are flexible structures, which respond to a change of their charge state by a profound reorganization of their geometrical structure or may even dissociate. It is thus important to understand the interrelation between the vibrational degrees of freedom of a singlemolecule junction and the electrical current flowing through the contact. In this thesis, we investigate vibrational effects in electron transport through singlemolecule junctions. For these studies, we calculate and analyze transport characteristics of both generic and first-principles based model systems of a molecular contact. To this end, we employ a master equation and a nonequilibrium Green's function approach. Both methods are suitable to describe this nonequilibrium transport problem and treat the interactions of the tunneling electrons on the molecular bridge non-perturbatively. This is particularly important with respect to the vibrational degrees of freedom, which may strongly interact with the tunneling electrons. We show in detail that the resulting

Vibration study of a vehicle suspension assembly with the finite element method

Science.gov (United States)

Cătălin Marinescu, Gabriel; Castravete, Ştefan-Cristian; Dumitru, Nicolae

2017-10-01

The main steps of the present work represent a methodology of analysing various vibration effects over suspension mechanical parts of a vehicle. A McPherson type suspension from an existing vehicle was created using CAD software. Using the CAD model as input, a finite element model of the suspension assembly was developed. Abaqus finite element analysis software was used to pre-process, solve, and post-process the results. Geometric nonlinearities are included in the model. Severe sources of nonlinearities such us friction and contact are also included in the model. The McPherson spring is modelled as linear spring. The analysis include several steps: preload, modal analysis, the reduction of the model to 200 generalized coordinates, a deterministic external excitation, a random excitation that comes from different types of roads. The vibration data used as an input for the simulation were previously obtained by experimental means. Mathematical expressions used for the simulation were also presented in the paper.

Equilibrium calculation for the electrolytic reduction process of the ACP

International Nuclear Information System (INIS)

Park, Byung Heung; Seo, Chung Seok; Yoon, Ji Sup

2006-01-01

The electrolytic reduction process is the most critical process of the advanced spent fuel conditioning process (ACP) since most of the chemical reactions take place during this reduction process in a molten salt bath. However, it is very difficult to observe the behavior of all the spent fuel elements by experiments. Therefore, a perspective calculation is required to predict how much the chemicals are distributed between the phases and which forms are stable in each phase. Chemical equilibria take place during the electrolytic reduction process. The reduction process uses a porous magnesia filter and the materials to be reduced are loaded into the filter, which means the filter, the cathode of the electrolytic reduction cell, acts as a packed-bed reactor. Lithium metal is produced by an electrolytic reaction in a molten Li 2 O-LiCl cell and the reaction is denoted as Eq. In this work, attention has been paid to the chemical reactions of Eq. since an electrochemical reaction is controlled easily by the supplied current and the extents of the chemical reactions are determined by considering many candidates species. Uranium oxides, for example, can be reduced to U 4 O 9 , UO 2 , and/or U when U 3 O 8 is fed to the electrolytic reduction process

Interference between vibration-to-translation and vibration-to-vibration energy transfer modes in diatomic molecules at high collision energies

International Nuclear Information System (INIS)

Shin, H.K.

1983-01-01

An explicit time dependent approach for simultaneous VT and VV energy transfer in diatom--diatom collisions is explored using the exponential form of ladder operators in the solution of the Schroedinger equation of motion. The collision of two hydrogen molecules is chosen to illustrate the extent of interference between VT and VV modes among various vibrational states. While vibrational energy transfer processes of nominally VT type can be treated with pure VT mode at low collision energies, the intermode coupling is found to be very important at collision energies of several hω. The occurrence of the coupling appears to be nearly universal in vibrational transitions at such energies. Exceptions to the coupling have been discussed

Vibration transducer calibration techniques

Science.gov (United States)

Brinkley, D. J.

1980-09-01

Techniques for the calibration of vibration transducers used in the Aeronautical Quality Assurance Directorate of the British Ministry of Defence are presented. Following a review of the types of measurements necessary in the calibration of vibration transducers, the performance requirements of vibration transducers, which can be used to measure acceleration, velocity or vibration amplitude, are discussed, with particular attention given to the piezoelectric accelerometer. Techniques for the accurate measurement of sinusoidal vibration amplitude in reference-grade transducers are then considered, including the use of a position sensitive photocell and the use of a Michelson laser interferometer. Means of comparing the output of working-grade accelerometers with that of previously calibrated reference-grade devices are then outlined, with attention given to a method employing a capacitance bridge technique and a method to be used at temperatures between -50 and 200 C. Automatic calibration procedures developed to speed up the calibration process are outlined, and future possible extensions of system software are indicated.

Application of the wavelet packet transform to vibration signals for surface roughness monitoring in CNC turning operations

Science.gov (United States)

García Plaza, E.; Núñez López, P. J.

2018-01-01

The wavelet packet transform method decomposes a time signal into several independent time-frequency signals called packets. This enables the temporary location of transient events occurring during the monitoring of the cutting processes, which is advantageous in monitoring condition and fault diagnosis. This paper proposes the monitoring of surface roughness using a single low cost sensor that is easily implemented in numerical control machine tools in order to make on-line decisions on workpiece surface finish quality. Packet feature extraction in vibration signals was applied to correlate the sensor signals to measured surface roughness. For the successful application of the WPT method, mother wavelets, packet decomposition level, and appropriate packet selection methods should be considered, but are poorly understood aspects in the literature. In this novel contribution, forty mother wavelets, optimal decomposition level, and packet reduction methods were analysed, as well as identifying the effective frequency range providing the best packet feature extraction for monitoring surface finish. The results show that mother wavelet biorthogonal 4.4 in decomposition level L3 with the fusion of the orthogonal vibration components (ax + ay + az) were the best option in the vibration signal and surface roughness correlation. The best packets were found in the medium-high frequency DDA (6250-9375 Hz) and high frequency ADA (9375-12500 Hz) ranges, and the feed acceleration component ay was the primary source of information. The packet reduction methods forfeited packets with relevant features to the signal, leading to poor results for the prediction of surface roughness. WPT is a robust vibration signal processing method for the monitoring of surface roughness using a single sensor without other information sources, satisfactory results were obtained in comparison to other processing methods with a low computational cost.

Effect of vibration loading on the fatigue life of part-through notched pipe

International Nuclear Information System (INIS)

Mittal, Rahul; Singh, P.K.; Pukazhendi, D.M.; Bhasin, V.; Vaze, K.K.; Ghosh, A.K.

2011-01-01

A systematic experimental and analytical study has been carried out to investigate the effect of vibration loading on the fatigue life of the piping components. Three Point bend (TPB) specimens machined from the actual pipe have been used for the evaluation of Paris constants by carrying out the experiments under vibration + cyclic and cyclic loading as per the ASTM Standard E647. These constants have been used for the prediction of the fatigue life of the pipe having part-through notch of a/t = 0.25 and aspect ratio (2c/a) of 10. Predicted results have shown the reduction in fatigue life of the notched pipe subjected to vibration + cyclic loading by 50% compared to that of cyclic loading. Predicted results have been validated by carrying out the full-scale pipe (with part-through notch) tests. Notched pipes were subjected to loading conditions such that the initial stress-intensity factor remains same as that of TPB specimen. Experimental results of the full-scale pipe tests under vibration + cyclic loading has shown the reduction in fatigue life by 70% compared to that of cyclic loading. Fractographic examination of the fracture surface of the tested specimens subjected to vibration + cyclic loading have shown higher presence of brittle phases such as martensite (in the form of isolated planar facets) and secondary micro cracks. This could be the reason for the reduction of fatigue life in pipe subjected to vibration + cyclic loading. - Highlights: → Vibration loading affects fatigue crack growth rate. → Crack initiation life depends on crack tip radius. → Crack initiation life depends on the characteristic distance. → Characteristic distance depends on the loading conditions. → Vibration + cyclic load gives lower fatigue life.

Proliferation resistance of the lithium reduction process

International Nuclear Information System (INIS)

Ko, W. I.; Ha, J. H.; Lee, S. Y.; Song, D. Y.; Kim, H. D.; Park, S. W.

2002-01-01

This paper addresses the characteristics of proliferation resistance of the lithium reduction process and international domestic safeguarding methods. In addition to dealing with qualitative features of the proliferation resistance, this study is emphasizing on the quantitative analysis of radiation barrier, which could be a significant accessibility barrier if the field is high enough to force a theft to shield the object during a theft. From the radiation barrier analysis, it is indicated that whole-body radiation dose is about 20 rem/hr at one meter of smelt and ingot metal of 40 kgHM, which could be considered to be a significant reduction in risk of theft. For safeguarding of this process, we propose a NDA concept for nuclear material accounting which is to measure the amount of curium in the reduction metal and associated process samples using a neutron coincidence counter and then to convert the curium mass into special nuclear material with predetermined curium ratios. For this, a well-type neutron coincidence counter with substantial shielding to protect the system from high gamma radiation is conceptually designed

Tensor-decomposed vibrational coupled-cluster theory: Enabling large-scale, highly accurate vibrational-structure calculations

Science.gov (United States)

Madsen, Niels Kristian; Godtliebsen, Ian H.; Losilla, Sergio A.; Christiansen, Ove

2018-01-01

A new implementation of vibrational coupled-cluster (VCC) theory is presented, where all amplitude tensors are represented in the canonical polyadic (CP) format. The CP-VCC algorithm solves the non-linear VCC equations without ever constructing the amplitudes or error vectors in full dimension but still formally includes the full parameter space of the VCC[n] model in question resulting in the same vibrational energies as the conventional method. In a previous publication, we have described the non-linear-equation solver for CP-VCC calculations. In this work, we discuss the general algorithm for evaluating VCC error vectors in CP format including the rank-reduction methods used during the summation of the many terms in the VCC amplitude equations. Benchmark calculations for studying the computational scaling and memory usage of the CP-VCC algorithm are performed on a set of molecules including thiadiazole and an array of polycyclic aromatic hydrocarbons. The results show that the reduced scaling and memory requirements of the CP-VCC algorithm allows for performing high-order VCC calculations on systems with up to 66 vibrational modes (anthracene), which indeed are not possible using the conventional VCC method. This paves the way for obtaining highly accurate vibrational spectra and properties of larger molecules.

Features of measurement and processing of vibration signals registered on the moving parts of electrical machines

OpenAIRE

Gyzhko, Yuri

2011-01-01

Measurement and processing of vibration signals registered on the moving parts of the electrical machines using the diagnostic information-measuring system that uses Bluetooth wireless standard for the transmission of the measured data from moving parts of electrical machine is discussed.

Random vibrations theory and practice

CERN Document Server

Wirsching, Paul H; Ortiz, Keith

1995-01-01

Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...

Behaviour of actinide elements in the lithium reduction process. 1. Feasibility of the Li reduction process to UO2 and PuO2

International Nuclear Information System (INIS)

Usami, Tuyoshi; Kurata, Masateru; Yuda, Ryoichi; Kato, Tetsuya; Inoue, Tadashi; Sims, Howard; Jenkins, Jon

2000-01-01

Lithium reduction process has been developed to apply pyrochemical recycle process for oxide fuels. This process uses lithium metal as a reductant to convert oxides of actinide elements to metal. Lithium oxide generated in the reduction is to be dissolved in a molten lithium chloride bath to enhance reduction. The authors have measured the solubility of lithium oxide in lithium chloride, and then reduced uranium dioxide and plutonium dioxide. The solubility measured at 923 K was 8.8 wt.%. The uranium dioxide was completely reduced with no intermediate products and formed porous metal. Plutonium dioxide including 3% of americium dioxide was also reduced completely and formed molten metal. Even lithium oxide was just under saturation , plutonium could be reduced to metal. Shown from this result was easier reduction than predicted from thermodynamic data. Americium dioxide was also reduced at 1.8 wt% lithium oxide, but was not reduced at 8.8 wt.%. (author)

Vibration-type particle separation device with piezoceramic vibrator

Science.gov (United States)

Ooe, Katsutoshi; Doi, Akihiro

2008-12-01

During hemanalysis, it is necessary to separate blood cells from whole blood. Many blood separation methods, for example, centrifugation and filtering, are in practical use. However, the use of these methods involves problems from the perspectives of processing speed and processing volume. We develop new types of blood separation devices that use piezo-ceramic vibrators. The first device uses a capillary. One end of the capillary is fixed to the device frame, and the other is fixed to a piezo-ceramic vibrator. The vibrator transmits bending waves to the capillary. This device can process only a small amount of solution; therefore, it is not suitable for hemanalysis. In order to solve this problem, we developed a second device; this device has a pair of thin glass plates with a small gap as a substitute for the capillary used in the first device. These devices are based on the fact that particles heavier than water move toward transverse velocity antinodes while those lighter than water move toward velocity nodes. In this report, we demonstrate the highspeed separation of silica microbeads and 50-vol% glycerol water by using these devices. The first device can separate the abovementioned solution within 3 min while the second can separate it within 1 min. Both devices are driven by a rectangular wave of 15 to 20 Vpp. Furthermore, it has been confirmed that red blood cells are separated from diluted whole blood using the first device within approximately 1 min. These devices have transparency, so they can compose as the analysis system with the chemical analyzer easily.

Process and system for isotope separation using the selective vibrational excitation of molecules

International Nuclear Information System (INIS)

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

1976-01-01

This invention concerns the separation of isotopes by using the isotopically selective vibrational excitation and the vibration-translation reactions of the excited particles. UF 6 molecular mixed with a carrier gas, such as argon, are directed through a refrigerated chamber lighted by a laser radiation tuned to excite vibrationally the uranium hexafluoride molecules of a particular uranium isotope. The density of the carrier gas is preferably maintained above the density of the uranium hexafluoride to allow a greater collision probability of the vibrationally excited molecules with a carried molecule. In such a case, the vibrationally excited uranium hexafluoride will collide with a carrier gas molecule provoking the conversion of the excitation energy into a translation of the excited molecule, resulting in thermal energy or greater diffusibility than that of the other uranium hexafluoride molecules [fr

The vibrational properties of Chinese fir wood during moisture sorption process

Science.gov (United States)

Jiali Jiang; Jianxiong Lu; Zhiyong Cai

2012-01-01

The vibrational properties of Chinese fir (Cunninghamia lanceolata) wood were investigated in this study as a function of changes in moisture content (MC) and grain direction. The dynamic modulus of elasticity (DMOE) and logarithmic decrement σ were examined using a cantilever beam vibration testing apparatus. It was observed that DMOE and 6 of wood vaned...

Feedforward Control of Gear Mesh Vibration Using Piezoelectric Actuators

Directory of Open Access Journals (Sweden)

Gerald T. Montague

1994-01-01

Full Text Available This article presents a novel means for suppressing gear mesh related vibrations. The key components in this approach are piezoelectric actuators and a high-frequency, analog feed forward controller. Test results are presented and show up to a 70% reduction in gear mesh acceleration and vibration control up to 4500 Hz. The principle of the approach is explained by an analysis of a harmonically excited, general linear vibratory system.

Enhanced vibration diagnostics using vibration signature analysis

International Nuclear Information System (INIS)

Ahmed, S.; Shehzad, K.; Zahoor, Y.; Mahmood, A.; Bibi, A.

2001-01-01

Symptoms will appear in equipment, as well as in human beings. when 'suffering from sickness. Symptoms of abnormality in equipment are vibration, noise, deformation, temperature, pressure, electric current, crack, wearing, leakage etc. these are called modes of failure. If the mode of failure is vibration then the vibration signature analysis can be effectively used in order to diagnose the machinery problems. Much valuable information is contained within these vibration 'Spectra' or 'Signatures' but is only of use if the analyst can unlock its 'Secrets'. This paper documents a vibration problem in the motor of a centrifugal pump (Type ETA). It focuses mainly on the roll of modern vibration monitoring system in problem analysis. The problem experienced was the motor unstability and noise due to high vibration. Using enhanced vibration signature data, the problem was analyzed. which suggested that the rotor eccentricity was the cause of excessive noise and vibration in the motor. In conclusion, advanced electronic monitoring and diagnostic systems provide powerful information for machine's condition assessment and problem analysis. Appropriate interpretation and use of this information is important for accurate and effective vibration analysis. (author)

Bomb reduction of uranium tetrafluoride. Part II: Influence of the addition elements in the reduction process

International Nuclear Information System (INIS)

Anca Abati, R.; Lopez Rodriguez, M.

1962-01-01

This work shows the influence of uranium oxide and uranyl fluoride in the reduction of uranium with Ca and Mg. These additions are more harmful when using smaller bombs. The uranyl fluoride has influence in the reduction process; the curves yield-concentration shows two regions depending upon the salt concentration. The behaviour of this addition in these regions can be explained following the different decompositions that can take place during the reduction process. (Author) 9 refs

SELECTION AND PRELIMINARY EVALUATION OF ALTERNATIVE REDUCTANTS FOR SRAT PROCESSING

Energy Technology Data Exchange (ETDEWEB)

Stone, M.; Pickenheim, B.; Peeler, D.

2009-06-30

Defense Waste Processing Facility - Engineering (DWPF-E) has requested the Savannah River National Laboratory (SRNL) to perform scoping evaluations of alternative flowsheets with the primary focus on alternatives to formic acid during Chemical Process Cell (CPC) processing. The reductants shown below were selected for testing during the evaluation of alternative reductants for Sludge Receipt and Adjustment Tank (SRAT) processing. The reductants fall into two general categories: reducing acids and non-acidic reducing agents. Reducing acids were selected as direct replacements for formic acid to reduce mercury in the SRAT, to acidify the sludge, and to balance the melter REDuction/OXidation potential (REDOX). Non-acidic reductants were selected as melter reductants and would not be able to reduce mercury in the SRAT. Sugar was not tested during this scoping evaluation as previous work has already been conducted on the use of sugar with DWPF feeds. Based on the testing performed, the only viable short-term path to mitigating hydrogen generation in the CPC is replacement of formic acid with a mixture of glycolic and formic acids. An experiment using glycolic acid blended with formic on an 80:20 molar basis was able to reduce mercury, while also targeting a predicted REDuction/OXidation (REDOX) of 0.2 expressed as Fe{sup 2+}/{Sigma}Fe. Based on this result, SRNL recommends performing a complete CPC demonstration of the glycolic/formic acid flowsheet followed by a design basis development and documentation. Of the options tested recently and in the past, nitric/glycolic/formic blended acids has the potential for near term implementation in the existing CPC equipment providing rapid throughput improvement. Use of a non-acidic reductant is recommended only if the processing constraints to remove mercury and acidify the sludge acidification are eliminated. The non-acidic reductants (e.g. sugar) will not reduce mercury during CPC processing and sludge acidification would

Aircraft gas turbine engine vibration diagnostics

Directory of Open Access Journals (Sweden)

Stanislav Fábry

2017-11-01

Full Text Available In the Czech and Slovak aviation are in service elderly aircrafts, usually produced in former Soviet Union. Their power units can be operated in more efficient way, in case of using additional diagnostic methods that allow evaluating their health. Vibration diagnostics is one of the methods indicating changes of rotational machine dynamics. Ground tests of aircraft gas turbine engines allow vibration recording and analysis. Results contribute to airworthiness evaluation and making corrections, if needed. Vibration sensors distribution, signal recording and processing are introduced in a paper. Recorded and re-calculated vibration parameters are used in role of health indicators.

Research Amplitudo Vibration On Holder Due To The Process Of Lathe Nozzle Rocket RX 450

Science.gov (United States)

Ediwan; Budi Djatmiko, Agus; Dody Arisandi, EfFendy; Purnomo, Heri; Ibadi, Mahfud

2018-04-01

The main function of the rocket nozzle is to convert the enthalpy efficiency from combustion gas to kinetic energy and also to make high velocity out of the gas. The rocket nozzle usually consists of a converging and diverging part. With a smaller area on the neck and enlarged at the exit area. The velocity flow through the nozzle enlarges into the speed of sound through the neck and then becomes super sonic in the divergent part. Nozzle making or machining using conventional lathes, first performed is drilling on a massive metal that is bonded to the veneer, then after a sufficient gap is done deep-boring. At the time of the process of lathe in the nozzle RX 450 there is an obstacle that is vibrating tool holder chisel or holder so it is worried about not precision of the process of lathe. This should not happen because it can cause failure in the latter for it needs to be studied and studied further so that the lathe process goes accordingly. The holder material of ST 60 with a modulus of elasticity 200 GPa and a nozzle material of AISI 4340 alloy steel with σyield = 470 MPa, Shear Modulus G = 80 GPa. The purpose of this research is to observe the amplitude of vibration on the holder due to RX- 450 nozzle lathe processing for the purpose of amplitude that occurs in accordance with the desired so that the nozzle structure is no damage process. The result of the research was obtained holder with length (L) 80cm, profile width (B) 5 cm, height of profile (H) 10 cm, turning machine ω = 8.98 rad / sec and natural holder frequency ωn = 89.8 rad / second, Amplitude of vibration of δ = 1.21 mm, while the amplitude of the design X = 1.22 mm From the results of this study it can be said that the holder of a chisel or holder can be used as a tool at the time of RX nozzle retrieval process and is quite safe because it works under the condition ω/ω n Rocket Payload "AKPV Engineering University of Wyoming 2009 )

Universality in the dynamical properties of seismic vibrations

Science.gov (United States)

Chatterjee, Soumya; Barat, P.; Mukherjee, Indranil

2018-02-01

We have studied the statistical properties of the observed magnitudes of seismic vibration data in discrete time in an attempt to understand the underlying complex dynamical processes. The observed magnitude data are taken from six different geographical locations. All possible magnitudes are considered in the analysis including catastrophic vibrations, foreshocks, aftershocks and commonplace daily vibrations. The probability distribution functions of these data sets obey scaling law and display a certain universality characteristic. To investigate the universality features in the observed data generated by a complex process, we applied Random Matrix Theory (RMT) in the framework of Gaussian Orthogonal Ensemble (GOE). For all these six places the observed data show a close fit with the predictions of RMT. This reinforces the idea of universality in the dynamical processes generating seismic vibrations.

Research of process of filtration of salt water by bulk filters with the use of vibration

Directory of Open Access Journals (Sweden)

A. I. Krikun

2018-01-01

Full Text Available For the purification of process water from impurities at fish processing plants, a large number of filtering devices are currently used, differing in their design parameters (mesh, woven, disco, etc.. However, in practice, these filtering devices are mainly used as the first stage of water treatment, since they can not provide sufficient quality of the filtrate. The most effective, as numerous studies of scientists of our country and the world show, are bulk granular filters. Their main advantages over other devices of similar designation are: they have a simple and reliable design; resistant to aggressive operating conditions; they are capable of effectively purifying seawater from mechanical impurities at relatively low pressure; most economical; have a filtering load capable of a long time to work without regeneration (the approximate service life of a grain-loading is 3 to 5 years etc. In this article, the influence of vibration effects on the filtration of sea water in a designed and fabricated filter unit with bulk granular materials of natural and artificial origin, the design of which is protected by two patents for the utility model. The results of the study are presented, revealing the degree of influence of the intensity of vibration of the perforated partitioning wall on the state of bulk granular materials located on it (segregation by size, stratified vibro-packing, compacting or loosening of a layer of granular material. The dependences of the capacity of the filtration unit on the amplitude, frequency and the vibration intensity factor have been experimentally established, which made it possible to establish rational vibration parameters of the perforated septum, under which the filtering layer becomes denser, the porosity of the loading decreases, and the precipitate does not break into the filtrate.

Vibrations of wind power plants; Schwingungen von Windenergieanlagen

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

Within the meeting of the department vibration engineering of the Association of German Engineers (Duesseldorf, Federal Republic of Germany) between 3rd and 4th February, 2010 in Hanover (Federal Republic of Germany) the following lectures are presented: (1) Reduction of forced strengths generated by wagging and snaking of the rotor in the power strain of wind power plants (F. Mitsch); (2) Reduction of vibrations at wind power plants by means of active additional systems (S. Katz, S. Pankoke, N. Loix); (3) Reduction of vibrations by means of balancing and alignment (E. Becker, M. Kenzler); (4) Active absorber for reducing tonal emissions of vibration at wind power plants (R. Neugebauer, M. Linke, H. Kunze, M. Ulrich); (5) Control structures for damping torsion vibrations and peak loads in the power strain of wind power converters (C. Sourkounis); (6) Possibilities of a non-contact investigation of vibrations at wind power plants (R. Behrendt, E. Reimers, H. Wiegers); (7) Influences on the loadability of CMS statements (R. Wirth); (8) Recording modal structural properties with sensor grids and methods of operational modal analysis (A. Friedmann, D. Mayer, M. Koch, M. Kauba, T. Melz); (9) Early failure detection of damages of roller bearings in wind power gear units with variable speed (B. Hacke, G. Poll); (10) Condition monitoring in wind power plants - structure monitoring and life time monitoring of wind power plants (SCMS and LCMS) (H. Lange); (11) Development of a model-based structural health monitoring system for condition monitoring of rotor blades (C. Ebert, H. Friedmann, F.O. Henkel, B. Frankenstein, L. Schubert); (12) Efficient remote monitoring at wind power plants by means of an external diagnosis centre (G. Ceglarek); (13) Accurate turbine modelling at component and assembly level for durability and acoustic analysis (D. v. Werner, W. Hendricx); (14) Possibilities of the investigation of the dynamic behaviour of power strains in wind power plants by

Mathematical modeling of vibration processes in reinforced concrete structures for setting up crack initiation monitoring

Science.gov (United States)

Bykov, A. A.; Matveenko, B. P.; Serovaev, G. S.; Shardakov, I. N.; Shestakov, A. P.

2015-03-01

The contemporary construction industry is based on the use of reinforced concrete structures, but emergency situations resulting in fracture can arise in their exploitation. In a majority of cases, reinforced concrete fracture is realized as the process of crack formation and development. As a rule, the appearance of the first cracks does not lead to the complete loss of the carrying capacity but is a fracture precursor. One method for ensuring the safe operation of building structures is based on crack initiation monitoring. A vibration method for the monitoring of reinforced concrete structures is justified in this paper. An example of a reinforced concrete beam is used to consider all stages related to the analysis of the behavior of natural frequencies in the development of a crack-shaped defect and the use of the obtained numerical results for the vibration test method. The efficiency of the method is illustrated by the results of modeling of the physical part of the method related to the analysis of the natural frequency evolution as a response to the impact action in the crack development process.

Denoising of Mechanical Vibration Signals Using Quantum-Inspired Adaptive Wavelet Shrinkage

Directory of Open Access Journals (Sweden)

Yan-long Chen

2014-01-01

Full Text Available The potential application of a quantum-inspired adaptive wavelet shrinkage (QAWS technique to mechanical vibration signals with a focus on noise reduction is studied in this paper. This quantum-inspired shrinkage algorithm combines three elements: an adaptive non-Gaussian statistical model of dual-tree complex wavelet transform (DTCWT coefficients proposed to improve practicability of prior information, the quantum superposition introduced to describe the interscale dependencies of DTCWT coefficients, and the quantum-inspired probability of noise defined to shrink wavelet coefficients in a Bayesian framework. By combining all these elements, this signal processing scheme incorporating the DTCWT with quantum theory can both reduce noise and preserve signal details. A practical vibration signal measured from a power-shift steering transmission is utilized to evaluate the denoising ability of QAWS. Application results demonstrate the effectiveness of the proposed method. Moreover, it achieves better performance than hard and soft thresholding.

Input Shaping to Reduce Solar Array Structural Vibrations

Science.gov (United States)

Doherty, Michael J.; Tolson, Robert J.

1998-01-01

Structural vibrations induced by actuators can be minimized using input shaping. Input shaping is a feedforward method in which actuator commands are convolved with shaping functions to yield a shaped set of commands. These commands are designed to perform the maneuver while minimizing the residual structural vibration. In this report, input shaping is extended to stepper motor actuators. As a demonstration, an input-shaping technique based on pole-zero cancellation was used to modify the Solar Array Drive Assembly (SADA) actuator commands for the Lewis satellite. A series of impulses were calculated as the ideal SADA output for vibration control. These impulses were then discretized for use by the SADA stepper motor actuator and simulated actuator outputs were used to calculate the structural response. The effectiveness of input shaping is limited by the accuracy of the knowledge of the modal frequencies. Assuming perfect knowledge resulted in significant vibration reduction. Errors of 10% in the modal frequencies caused notably higher levels of vibration. Controller robustness was improved by incorporating additional zeros in the shaping function. The additional zeros did not require increased performance from the actuator. Despite the identification errors, the resulting feedforward controller reduced residual vibrations to the level of the exactly modeled input shaper and well below the baseline cases. These results could be easily applied to many other vibration-sensitive applications involving stepper motor actuators.

Detection system for location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongbing, E-mail: liuhb07@mails.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education P. R. China, Beijing 100084 (China); Du, Dong, E-mail: dudong@tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education P. R. China, Beijing 100084 (China); Huang, An; Chang, Baohua; Han, Zandong [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education P. R. China, Beijing 100084 (China); He, Ayada [Shanghai Electric Power Generation Group Shanghai Generator Works, Shanghai 200240 (China)

2016-08-15

Highlights: • A detection system for locations of pebbles transported in pipes is introduced. • The detection system is based on vibration signal processing, which is original. • The characteristics of the vibration signals of the pipe are analyzed. • The experiment shows that the detection results are accurate. • The research provides an important basis for the design of the reactor. - Abstract: Pebble-bed high temperature gas-cooled reactors have many advantages such as inherent safety, high efficiency, etc., and have been considered as a candidate for Generation IV nuclear reactors. During the operation of the reactor, there are thousands of fuel pebbles transported in the pipes outside the core by gravity and helium flow. The pattern of the pipes which consist of straight and arc sections is very complex. When a fuel pebble is transported, it will constantly collide with the pipes, especially in the arc sections. The collisions will lead to the vibration of the pipes. This paper aims to provide a detection system for the location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing. Before the reactor is running, the system acquires the vibration signals of several key sections by sensors. Then the frequency characteristics of the signals are obtained by joint time–frequency analysis. When the reactor is running, the system detects the signals and processes them based on their frequency characteristics in real time. According to the results of the processing, the system can correctly judge whether the fuel pebble has passed through the section and records the time of the passing. The experiment validates the accuracy and reliability of the detection results. In this way, the operational condition of the reactor can be monitored so that the normal running of the reactor can be ensured. Additionally, the detection data are of great significance to the evaluation and optimization of the reactor performance

Detection system for location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing

International Nuclear Information System (INIS)

Liu, Hongbing; Du, Dong; Huang, An; Chang, Baohua; Han, Zandong; He, Ayada

2016-01-01

Highlights: • A detection system for locations of pebbles transported in pipes is introduced. • The detection system is based on vibration signal processing, which is original. • The characteristics of the vibration signals of the pipe are analyzed. • The experiment shows that the detection results are accurate. • The research provides an important basis for the design of the reactor. - Abstract: Pebble-bed high temperature gas-cooled reactors have many advantages such as inherent safety, high efficiency, etc., and have been considered as a candidate for Generation IV nuclear reactors. During the operation of the reactor, there are thousands of fuel pebbles transported in the pipes outside the core by gravity and helium flow. The pattern of the pipes which consist of straight and arc sections is very complex. When a fuel pebble is transported, it will constantly collide with the pipes, especially in the arc sections. The collisions will lead to the vibration of the pipes. This paper aims to provide a detection system for the location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing. Before the reactor is running, the system acquires the vibration signals of several key sections by sensors. Then the frequency characteristics of the signals are obtained by joint time–frequency analysis. When the reactor is running, the system detects the signals and processes them based on their frequency characteristics in real time. According to the results of the processing, the system can correctly judge whether the fuel pebble has passed through the section and records the time of the passing. The experiment validates the accuracy and reliability of the detection results. In this way, the operational condition of the reactor can be monitored so that the normal running of the reactor can be ensured. Additionally, the detection data are of great significance to the evaluation and optimization of the reactor performance

An Overview of Recent Automotive Applications of Active Vibration Control

National Research Council Canada - National Science Library

Kowalczyk, K; Svaricek, F; Bohn, C; Karkosch, H

2004-01-01

.... Continental has developed and implemented prototypes of active mounting systems on various test vehicles and demonstrated that significant reductions in noise and vibration levels are achievable...

Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process

Energy Technology Data Exchange (ETDEWEB)

Moussavi, Gholamreza, E-mail: moussavi@modares.ac.ir; Shekoohiyan, Sakine

2016-11-15

Highlights: • Simultaneous advanced oxidation and reduction processes were explored in VUV system. • Complete reduction of nitrate to N{sub 2} was achieved at the presence of acetaminophen. • Complete degradation of acetaminophen was achieved at the presence of nitrate. • Over 95% of acetaminophen was mineralized in the VUV photoreactor. • VUV is a chemical-less advanced process for treating water emerging contaminants. - Abstract: This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO· while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N{sub 2} selectivity achieved at HRT of 80 min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80 min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate.

Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process

International Nuclear Information System (INIS)

Moussavi, Gholamreza; Shekoohiyan, Sakine

2016-01-01

Highlights: • Simultaneous advanced oxidation and reduction processes were explored in VUV system. • Complete reduction of nitrate to N_2 was achieved at the presence of acetaminophen. • Complete degradation of acetaminophen was achieved at the presence of nitrate. • Over 95% of acetaminophen was mineralized in the VUV photoreactor. • VUV is a chemical-less advanced process for treating water emerging contaminants. - Abstract: This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO· while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N_2 selectivity achieved at HRT of 80 min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80 min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate.

Dynamical Behavior of a Pseudoelastic Vibration Absorber Using Shape Memory Alloys

Directory of Open Access Journals (Sweden)

Hugo De S. Oliveira

2017-01-01

Full Text Available The tuned vibration absorber (TVA provides vibration reduction of a primary system subjected to external excitation. The idea is to increase the number of system degrees of freedom connecting a secondary system to the primary system. This procedure promotes vibration reduction at its design forcing frequency but two new resonance peaks appear introducing critical behaviors that must be avoided. The use of shape memory alloys (SMAs can improve the performance of the classical TVA establishing an adaptive TVA (ATVA. This paper deals with the nonlinear dynamics of a passive pseudoelastic tuned vibration absorber with an SMA element. In this regard, a single degree of freedom elastic oscillator is used to represent the primary system, while an extra oscillator with an SMA element represents the secondary system. Temperature dependent behavior of the system allows one to change the system response avoiding undesirable responses. Nevertheless, hysteretic behavior introduces complex characteristics to the system dynamics. The influence of the hysteretic behavior due to stress-induced phase transformation is investigated. The ATVA performance is evaluated by analyzing primary system maximum vibration amplitudes for different forcing amplitudes and frequencies. Numerical simulations establish comparisons of the ATVA results with those obtained from the classical TVA. A parametric study is developed showing the best performance conditions and this information can be useful for design purposes.

Homogeneity Analysis of a MEMS-based PZT Thick Film Vibration Energy Harvester Manufacturing Process

DEFF Research Database (Denmark)

Lei, Anders; Xu, Ruichao; Borregaard, Louise M.

2012-01-01

This paper presents a homogeneity analysis of a high yield wafer scale fabrication of MEMS-based unimorph silicon/PZT thick film vibration energy harvesters aimed towards vibration sources with peak vibrations in the range of around 300Hz. A wafer with a yield of 91% (41/45 devices) has been...

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.

Research on the design of fixture for motor vibration test

Science.gov (United States)

Shen, W. X.; Ma, W. S.; Zhang, L. W.

2018-03-01

The vibration reliability of the new energy automobile motor plays a very important role in driving safety, so it is very important to test the vibration durability of the motor. In the vibration test process, the fixture is very important, simulated road spectrum signal vibration can be transmitted without distortion to the motor through the fixture, fixture design directly affect the result of vibration endurance test. On the basis of new energy electric vehicle motor concrete structure, Two fixture design and fixture installation schemes for lateral cantilever type and base bearing type are put forward in this article, the selection of material, weighting process, middle alignment process and manufacturing process are summarized.The modal analysis and frequency response calculation of the fixture are carried out in this design, combine with influence caused by fixture height and structure profile on response frequency, the response frequency of each order of the fixture is calculated, then ultimately achieve the purpose of guiding the design.

Active Low-frequency Vertical Vibration Isolation System for Precision Measurements

Institute of Scientific and Technical Information of China (English)

WU Kang; LI Gang; HU Hua; WANG Lijun

2017-01-01

Low-frequency vertical vibration isolation systems play important roles in precision measurements to reduce seismic and environmental vibration noise.Several types of active vibration isolation systems have been developed.However,few researches focus on how to optimize the test mass install position in order to improve the vibration transmissibility.An active low-frequency vertical vibration isolation system based on an earlier instrument,the Super Spring,is designed and implemented.The system,which is simple and compact,consists of two stages:a parallelogram-shaped linkage to ensure vertical motion,and a simple spring-mass system.The theoretical analysis of the vibration isolation system is presented,including terms erroneously ignored before.By carefully choosing the mechanical parameters according to the above analysis and using feedback control,the resonance frequency of the system is reduced from 2.3 to 0.03 Hz,a reduction by a factor of more than 75.The vibration isolation system is installed as an inertial reference in an absolute gravimeter,where it improved the scatter of the absolute gravity values by a factor of 5.The experimental results verifies the improved performance of the isolation system,making it particularly suitable for precision experiments.The improved vertical vibration isolation system can be used as a prototype for designing high-performance active vertical isolation systems.An improved theoretical model of this active vibration isolation system with beam-pivot configuration is proposed,providing fundamental guidelines for vibration isolator design and assembling.

The effects of vibration-reducing gloves on finger vibration

Science.gov (United States)

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

2015-01-01

Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new

Technology for Transient Simulation of Vibration during Combustion Process in Rocket Thruster

Science.gov (United States)

Zubanov, V. M.; Stepanov, D. V.; Shabliy, L. S.

2018-01-01

The article describes the technology for simulation of transient combustion processes in the rocket thruster for determination of vibration frequency occurs during combustion. The engine operates on gaseous propellant: oxygen and hydrogen. Combustion simulation was performed using the ANSYS CFX software. Three reaction mechanisms for the stationary mode were considered and described in detail. The way for obtaining quick CFD-results with intermediate combustion components using an EDM model was found. The way to generate the Flamelet library with CFX-RIF was described. A technique for modeling transient combustion processes in the rocket thruster was proposed based on the Flamelet library. A cyclic irregularity of the temperature field like vortex core precession was detected in the chamber. Frequency of flame precession was obtained with the proposed simulation technique.

Effect of some additives on mass transfer coefficient at a vibrating horizontal screen

Energy Technology Data Exchange (ETDEWEB)

Nosier, S.A.; El-Abd, M.Z. [Chemical Engineering Dept., Faculty of Engineering, Alexandria Univ. (Egypt); Zaki, M.M. [Environmental Engineering Dept., Faculty of Engineering, Zagazig Univ. (Egypt)

1998-01-01

The addition of small amounts of high molecular weight substances, such as polymers and surface-active agents, to fluids can produce significant reduction of friction in turbulent flow. The objectiv of the present work is to study the effect of drag-reducing additives such as Polyox WSR 301 and sodium lauryl sulfate (anionic surfactant) on the rate of mass transfer at a vibrating horizontal screen. The variables studied were the concentration of polymer and surfactant, frequency of vibration and amplitude of vibration. (orig.)

The Influence of Tractor-Seat Height above the Ground on Lateral Vibrations

Directory of Open Access Journals (Sweden)

Jaime Gomez-Gil

2014-10-01

Full Text Available Farmers experience whole-body vibrations when they drive tractors. Among the various factors that influence the vibrations to which the driver is exposed are terrain roughness, tractor speed, tire type and pressure, rear axle width, and tractor seat height above the ground. In this paper the influence of tractor seat height above the ground on the lateral vibrations to which the tractor driver is exposed is studied by means of a geometrical and an experimental analysis. Both analyses show that: (i lateral vibrations experienced by a tractor driver increase linearly with tractor-seat height above the ground; (ii lateral vibrations to which the tractor driver is exposed can equal or exceed vertical vibrations; (iii in medium-size tractors, a feasible 30 cm reduction in the height of the tractor seat, which represents only 15% of its current height, will reduce the lateral vibrations by around 20%; and (iv vertical vibrations are scarcely influenced by tractor-seat height above the ground. The results suggest that manufacturers could increase the comfort of tractors by lowering tractor-seat height above the ground, which will reduce lateral vibrations.

Study on the separation effect of high-speed ultrasonic vibration cutting.

Science.gov (United States)

Zhang, Xiangyu; Sui, He; Zhang, Deyuan; Jiang, Xinggang

2018-07-01

High-speed ultrasonic vibration cutting (HUVC) has been proven to be significantly effective when turning Ti-6Al-4V alloy in recent researches. Despite of breaking through the cutting speed restriction of the ultrasonic vibration cutting (UVC) method, HUVC can also achieve the reduction of cutting force and the improvements in surface quality and cutting efficiency in the high-speed machining field. These benefits all result from the separation effect that occurs during the HUVC process. Despite the fact that the influences of vibration and cutting parameters have been discussed in previous researches, the separation analysis of HUVC should be conducted in detail in real cutting situations, and the tool geometry parameters should also be considered. In this paper, three situations are investigated in details: (1) cutting without negative transient clearance angle and without tool wear, (2) cutting with negative transient clearance angle and without tool wear, and (3) cutting with tool wear. And then, complete separation state, partial separation state and continuous cutting state are deduced according to real cutting processes. All the analysis about the above situations demonstrate that the tool-workpiece separation will take place only if appropriate cutting parameters, vibration parameters, and tool geometry parameters are set up. The best separation effect was obtained with a low feedrate and a phase shift approaching 180 degrees. Moreover, flank face interference resulted from the negative transient clearance angle and tool wear contributes to an improved separation effect that makes the workpiece and tool separate even at zero phase shift. Finally, axial and radial transient cutting force are firstly obtained to verify the separation effect of HUVC, and the cutting chips are collected to weigh the influence of flank face interference. Copyright © 2018 Elsevier B.V. All rights reserved.

Vibration tests on single heat exchanger tubes in air and static water

International Nuclear Information System (INIS)

Collinson, A.E.; Warneford, I.P.

1978-07-01

The vibrational characteristics of a 7 span straight tube and a 26 span U-tube have been investigated for the effects of fluid medium (air/water), tube-grid clearance, tube-grid contact force, vibration transmission and scale. Measured frequency response and mode shapes compared favourably with theoretical values, vibration with pin-pin tube support being most readily excited. The frequency reduction on immersion in water corresponded to an added mass equivalent to the liquid displaced mass. Dynamic magnifiers varied in the range 12 to 135 with mean values of 30 to 40 in water and 45 to 60 in air. Principal vibration modes and damping values were reproducible in a half-scale model of a U-tube. (author)

Formulation and process considerations for the design of sildenafil-loaded polymeric microparticles by vibrational spray-drying

DEFF Research Database (Denmark)

Beck-Broichsitter, Moritz; Bohr, Adam; Aragão-Santiago, Leticia

2017-01-01

CONTEXT AND OBJECTIVE: The current study reports the preparation and characterization of sildenafil-loaded poly(lactide-co-glycolide) (PLGA)-based microparticles (MPs) by means of vibrational spray-drying. Emphasis was placed on relevant formulation and process parameters with influence on the pr......CONTEXT AND OBJECTIVE: The current study reports the preparation and characterization of sildenafil-loaded poly(lactide-co-glycolide) (PLGA)-based microparticles (MPs) by means of vibrational spray-drying. Emphasis was placed on relevant formulation and process parameters with influence......), respectively. Furthermore, interactions between sildenafil and the PLGA matrix were observed for the spray-dried MPs. Optimization of spray-drying conditions allowed for a fabrication of defined MPs (size range of ∼4-8 μm) displaying a high sildenafil encapsulation efficiency (>90%) and sustained sildenafil...... properties of the prepared powders. CONCLUSION: Identification of relevant formulation and spray-drying parameters enabled the fabrication of tailored sildenafil-loaded PLGA-based MPs, which meet the needs of the individual application (e.g. controlled drug delivery to the lungs)....

Blade-Mounted Flap Control for BVI Noise Reduction Proof-of-Concept Test

Science.gov (United States)

Dawson, Seth; Hassan, Ahmed; Straub, Friedrich; Tadghighi, Hormoz

1995-01-01

This report describes a wind tunnel test of the McDonnell Douglas Helicopter Systems (MDHS) Active Flap Model Rotor at the NASA Langley 14- by 22-Foot Subsonic Tunnel. The test demonstrated that BVI noise reductions and vibration reductions were possible with the use of an active flap. Aerodynamic results supported the acoustic data trends, showing a reduction in the strength of the tip vortex with the deflection of the flap. Acoustic results showed that the flap deployment, depending on the peak deflection angle and azimuthal shift in its deployment schedule, can produce BVI noise reductions as much as 6 dB on the advancing and retreating sides. The noise reduction was accompanied by an increase in low frequency harmonic noise and high frequency broadband noise. A brief assessment of the effect of the flap on vibration showed that significant reductions were possible. The greatest vibration reductions (as much as 76%) were found in the four per rev pitching moment at the hub. Performance improvement cam results were inconclusive, as the improvements were predicted to be smaller than the resolution of the rotor balance.

Bevel Gearbox Fault Diagnosis using Vibration Measurements

Directory of Open Access Journals (Sweden)

Hartono Dennis

2016-01-01

Full Text Available The use of vibration measurementanalysis has been proven to be effective for gearbox fault diagnosis. However, the complexity of vibration signals observed from a gearbox makes it difficult to accurately detectfaults in the gearbox. This work is based on a comparative studyof several time-frequency signal processing methods that can be used to extract information from transient vibration signals containing useful diagnostic information. Experiments were performed on a bevel gearbox test rig using vibration measurements obtained from accelerometers. Initially, thediscrete wavelet transform was implementedfor vibration signal analysis to extract the frequency content of signal from the relevant frequency region. Several time-frequency signal processing methods werethen incorporated to extract the fault features of vibration signals and their diagnostic performances were compared. It was shown thatthe Short Time Fourier Transform (STFT could not offer a good time resolution to detect the periodicity of the faulty gear tooth due the difficulty in choosing an appropriate window length to capture the impulse signal. The Continuous Wavelet Transform (CWT, on the other hand, was suitable to detection of vibration transients generated by localized fault from a gearbox due to its multi-scale property. However, both methods still require a thorough visual inspection. In contrast, it was shown from the experiments that the diagnostic method using the Cepstrumanalysis could provide a direct indication of the faulty tooth without the need of a thorough visual inspection as required by CWT and STFT.

Diagnostic aspects of vibration-induced white finger.

Science.gov (United States)

Olsen, Niels

2002-01-01

Vibration-induced white finger (VWF) is a secondary type of Raynaud's phenomenon (RP) caused by exposure to hand-arm vibration. The present review concerns the cold-provoked attack of RP in vasospastic VWF. It concentrates on the most common clinical and laboratory methods used to diagnose RP in vibration-exposed subjects. Some physiological aspects of the attack of RP are mentioned to elucidate the diagnostic principles of the tests. Anamnestic diagnostics by medical interviews and questionnaires as well as cold-provocation tests with detection of finger colour, finger systolic blood pressure (FSP), recovery time of finger skin temperature and recovery time of normal nail colour after nail compression are mentioned. The discriminative capacity and the reproducibility of the tests are discussed. Cold-provocation tests with detection of finger colour or zero FSP during cooling are recommended to be used if an attack of RP has to be registered for diagnostic or medico-legal purposes in individual cases. An abnormal reduction in FSP during cooling makes a history of RP very probable and is a suitable laboratory test for groups of subjects. Both recovery tests may be useful screening tests in field studies of vibration-exposed subject groups.

A Combined Probe-Molecule, Mössbauer, Nuclear Resonance Vibrational Spectroscopy, and Density Functional Theory Approach for Evaluation of Potential Iron Active Sites in an Oxygen Reduction Reaction Catalyst

Energy Technology Data Exchange (ETDEWEB)

Kneebone, Jared L. [Univ. of Rochester, Rochester, NY (United States); Daifuku, Stephanie L. [Univ. of Rochester, Rochester, NY (United States); Kehl, Jeffrey A. [Univ. of Rochester, Rochester, NY (United States); Wu, Gang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chung, Hoon T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hu, Michael Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Alp, E. Ercan [Argonne National Lab. (ANL), Argonne, IL (United States); More, Karren L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zelenay, Piotr [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Holby, Edward F. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Neidig, Michael L. [Univ. of Rochester, Rochester, NY (United States)

2017-07-06

While non-precious metal M-N-C (M = Fe or Co) catalysts have been developed that are effective for the oxygen reduction reaction in polymer electrolyte fuel cells, no consensus has yet been reached regarding the nature of the M sites in these heterogeneous catalysts that are responsible for reaction with dioxygen (O₂). While multiple studies have developed correlations between Fe distributions in as-prepared catalysts and ORR activity, the direct identification of sites reactive towards O₂ or O₂-analog molecules remains a significant challenge. In the present study, we demonstrate a new approach to identifying and characterizing potential Fe active sites in complex ORR catalysts that combines an effective probe molecule (NO_(g)) Mössbauer spectroscopy and nuclear resonance vibrational spectroscopy (NRVS) with density functional theory (DFT) calculations. Mössbauer spectroscopic studies demonstrate that NO_(g) treatment of electrochemically reduced PANI-57Fe-C leads to selective reaction with only a sub-set of the Fe species present. Nuclear resonance vibrational spectroscopic studies identified new Fe-ligand vibrations associated with the site reactive towards NO_(g). DFT calculations of vibrational properties of a small selection of previously proposed active site structures suggest that graphene zig-zag edge hosted Fe-N structures may be responsible for the observed vibrational behavior with NO_(g) probe molecules. Moreover, such sites are likely also reactive to O₂, possibly serving as the ORR active sites in the synthesized materials.

Fiber optic vibration sensor using bifurcated plastic optical fiber

Science.gov (United States)

Abdullah, M.; Bidin, N.; Yasin, M.

2016-11-01

An extrinsic fiber optic vibration sensor is demonstrated for a fiber optic displacement sensor based on a bundled multimode fiber to measure a vibration frequency ranging from 100 until 3000 Hz. The front slope has a sensitivity of 0.1938mV/mm and linearity of 99.7% within a measurement range between 0.15-3.00 mm. By placing the diaphragm of the concave load-speaker within the linear range from the probe, the frequency of the vibration can be measured with error percentage of less than 1.54%. The graph of input against output frequency for low, medium and high frequency range show very high linearity up to 99%. Slope for low, medium, and high frequency range are calculated as 1.0026, 0.9934, and 1.0007 respectively. Simplicity, long term stability, low power consumption, wide dynamic and frequency ranges, noise reduction, ruggedness, linearity and light weight make it promising alternative to other well-establish methods for vibration frequency measurement.

Electromagnetic harvester for lateral vibration in rotating machines

Science.gov (United States)

de Araujo, Marcus Vinícius Vitoratti; Nicoletti, Rodrigo

2015-02-01

Energy harvesters are devices that convert mechanical energy, usually vibration, into electrical energy that can be used to supply low power circuits (e.g. sensors). In this work, an energy harvester is designed for converting the mechanical energy of the lateral vibrations of shafts into electrical energy. For that, permanent magnets are mounted in the shaft and coils are mounted in a fixed structure. A configuration analysis is performed to find the appropriated polarization of the magnets and orientation of the coils in order to have electromagnetic induction without resisting torque on the shaft. Experimental tests are done for different electrical configurations of the coils: independent, in series and, in parallel. The results show that more electric power is induced when the coils are connected in series, and vibration reduction is more evident when the coils are connected independently.

A new potential energy surface for vibration-vibration coupling in HF-HF collisions. Formulation and quantal scattering calculations

Science.gov (United States)

Schwenke, David W.; Truhlar, Donald G.

1988-04-01

We present new ab initio calculations of the HF-HF interaction potential for the case where both molecules are simultaneously displaced from their equilibrium internuclear distance. These and previous ab initio calculations are then fit to a new analytic representation which is designed to be efficient to evaluate and to provide an especially faithful account of the forces along the vibrational coordinates. We use the new potential for two sets of quantal scattering calculations for collisions in three dimensions with total angular momentum zero. First we test that the angular harmonic representation of the anisotropy is adequate by comparing quantal rigid rotator calculations to those carried out for potentials involving higher angular harmonics and for which the expansion in angular harmonics is systematically increased to convergence. Then we carry out large-scale quantal calculations of vibration-vibration energy transfer including the coupling of both sets of vibrational and rotational coordinates. These calculations indicate that significant rotational energy transfer accompanies the vibration-to-vibration energy transfer process.

The study of reductive reextraction of plutonium in the Purex process

International Nuclear Information System (INIS)

Poczynajlo, A.

1985-01-01

The methods of separation of U and Pu in the Purex process and the thermodynamic and kinetic properties of Pu(4) reductants are discussed. The kinetic equation of the process of reductive reextraction of plutonium for the first order reaction with respect to Pu(4) is derived. The kinetics of plutonium reextraction with the use of uranium (4), ascorbic acid and other reductants has been studied. The necessity of application of the stoichiometric excess of reductant has been explained by simultaneously occured reoxidation process of plutonium. The method of calculation of the steady- state plutonium concentration profiles has been elaborated for counter-current separation of U and Pu in multistage contactor. 90 refs., 20 tabs., 29 figs. (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 effect of vibrationally excited nitrogen on the low-latitude ionosphere

Directory of Open Access Journals (Sweden)

B. Jenkins

1997-11-01

Full Text Available The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O+ ions are converted to NO+ ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest effect being at the location of the equatorial trough.

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

Sensor-based vibration signal feature extraction using an improved composite dictionary matching pursuit algorithm.

Science.gov (United States)

Cui, Lingli; Wu, Na; Wang, Wenjing; Kang, Chenhui

2014-09-09

This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP) algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP) is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and reconstruction algorithm

Sensor-Based Vibration Signal Feature Extraction Using an Improved Composite Dictionary Matching Pursuit Algorithm

Directory of Open Access Journals (Sweden)

Lingli Cui

2014-09-01

Full Text Available This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and

Chatter reduction in boring process by using piezoelectric shunt damping with experimental verification

Science.gov (United States)

Yigit, Ufuk; Cigeroglu, Ender; Budak, Erhan

2017-09-01

Chatter is a self-excited type of vibration that develops during machining due to process-structure dynamic interactions resulting in modulated chip thickness. Chatter is an important problem as it results in poor surface quality, reduced productivity and tool life. The stability of a cutting process is strongly influenced by the frequency response function (FRF) at the cutting point. In this study, the effect of piezoelectric shunt damping on chatter vibrations in a boring process is studied. In piezoelectric shunt damping method, an electrical impedance is connected to a piezoelectric transducer which is bonded on cutting tool. Electrical impedance of the circuit consisting of piezoceramic transducer and passive shunt is tuned to the desired natural frequency of the cutting tool in order to maximize damping. The optimum damping is achieved in analytical and finite element models (FEM) by using a genetic algorithm focusing on the real part of the tool point FRF rather than the amplitude. Later, a practical boring bar is considered where the optimum circuit parameters are obtained by the FEM. Afterwards, the effect of the optimized piezoelectric shunt damping on the dynamic rigidity and absolute stability limit of the cutting process are investigated experimentally by modal analysis and cutting tests. It is both theoretically and experimentally shown that application of piezoelectric shunt damping results in a significant increase in the absolute stability limit in boring operations.

Active Vibration Control of a Railway Vehicle Carbody Using Piezoelectric Elements

Science.gov (United States)

Molatefi, Habibollah; Ayoubi, Pejman; Mozafari, Hozhabr

2017-07-01

In recent years and according to modern transportation development, rail vehicles are manufactured lighter to achieve higher speed and lower transportation costs. On the other hand, weight reduction of rail vehicles leads to increase the structural vibration. In this study, Active Vibration Control of a rail vehicle using piezoelectric elements is investigated. The optimal control employed as the control approach regard to the first two modes of vibration. A simplified Car body structure is modeled in Matlab using the finite element theory by considering six DOF beam element and then the Eigen functions and mode shapes are derived. The surface roughness of different classes of rail tracks have been obtained using random vibration theory and applied to the secondary suspension as the excitation of the structure; Then piezoelectric mounted where the greatest moments were captured. The effectiveness of Piezoelectric in structural vibrations attenuation of car body is demonstrated through the state space equations and its effect on modal coefficient.

High precision NC lathe feeding system rigid-flexible coupling model reduction technology

Science.gov (United States)

Xuan, He; Hua, Qingsong; Cheng, Lianjun; Zhang, Hongxin; Zhao, Qinghai; Mao, Xinkai

2017-08-01

This paper proposes the use of dynamic substructure method of reduction of order to achieve effective reduction of feed system for high precision NC lathe feeding system rigid-flexible coupling model, namely the use of ADAMS to establish the rigid flexible coupling simulation model of high precision NC lathe, and then the vibration simulation of the period by using the FD 3D damper is very effective for feed system of bolt connection reduction of multi degree of freedom model. The vibration simulation calculation is more accurate, more quickly.

Modelling of slag emulsification and slag reduction in CAS-OB process

OpenAIRE

Sulasalmi, P. (Petri)

2016-01-01

Abstract Composition Adjustment by Sealed argon bubbling – Oxygen Blowing (CAS-OB) process is a ladle treatment process that was developed for chemical heating and alloying of steel. The main stages of the process are heating, (possible) alloying and reduction of slag. The CAS-OB process aims for homogenization and control of the composition and temperature of steel. In this dissertation, a mathematical reaction model was developed for the slag reduction stage of the CAS-OB process. Sl...

[Occupational standing vibration rate and vibrational diseases].

Science.gov (United States)

Karnaukh, N G; Vyshchipan, V F; Haumenko, B S

2003-12-01

Occupational standing vibration rate is proposed in evaluating a degree of impairment of an organism activity. It will allow more widely to introduce specification of quality and quantity in assessment of the development of vibrational disease. According out-patient and inpatient obtained data we have established criterial values of functional changes in accordance with accumulated occupational standing vibration rate. The nomogram was worked out for defining a risk of the development of vibrational disease in mine workers. This nomogram more objectively can help in diagnostics of the disease.

Fuzzy Multicriteria Model for Selection of Vibration Technology

Directory of Open Access Journals (Sweden)

María Carmen Carnero

2016-01-01

Full Text Available The benefits of applying the vibration analysis program are well known and have been so for decades. A large number of contributions have been produced discussing new diagnostic, signal treatment, technical parameter analysis, and prognosis techniques. However, to obtain the expected benefits from a vibration analysis program, it is necessary to choose the instrumentation which guarantees the best results. Despite its importance, in the literature, there are no models to assist in taking this decision. This research describes an objective model using Fuzzy Analytic Hierarchy Process (FAHP to make a choice of the most suitable technology among portable vibration analysers. The aim is to create an easy-to-use model for processing, manufacturing, services, and research organizations, to guarantee adequate decision-making in the choice of vibration analysis technology. The model described recognises that judgements are often based on ambiguous, imprecise, or inadequate information that cannot provide precise values. The model incorporates judgements from several decision-makers who are experts in the field of vibration analysis, maintenance, and electronic devices. The model has been applied to a Health Care Organization.

Vibration reduction and power generation with piezoceramic sheets mounted to a flexible shaft

NARCIS (Netherlands)

Sloetjes, P.J.; de Boer, Andries

2008-01-01

A flexible shaft with surface-mounted piezoceramic sheets and strain sensors is considered which suffers from resonance and self-excited vibration. Frequency domain models, time domain simulations, and control experiments are used to analyze active modal damping and active modal balancing methods.

Modelling and processing of data from a fibre-optic sensor of vibrations

International Nuclear Information System (INIS)

Morawski, R Z; Makowski, P L; Michalik, L; Domanski, A W

2010-01-01

A new technique of vibration sensing, based on a polarimetric fibre-optic strain sensor, is presented; it is designed for localisation of multiple sources of disturbances in a broad spectrum without using fibre gratings. A mathematical model of the sensor is used for development of a variational method for estimation of amplitudes of component vibrations on the basis of noisy samples of the voltage at the output of the sensor.

Process optimization for ultrasonic vibration assisted polishing of micro-structured surfaces on super hard material

Science.gov (United States)

Sun, Zhiyuan; Guo, Bing; Rao, Zhimin; Zhao, Qingliang

2014-08-01

In consideration of the excellent property of SiC, the ground micro-structured surface quality is hard to meet the requirement - consequently the ultrasonic vibration assisted polishing (UVAP) of micro-structures of molds is proposed in this paper. Through the orthogonal experiment, the parameters of UVAP of micro-structures were optimized. The experimental results show that, abrasive polishing process, the effect of the workpiece feed rate on the surface roughness (Ra), groove tip radius (R) and material removal rate (MRR) of micro-structures is significant. While, the UVAP, the most significant effect factor for Ra, R and MRR is the ultrasonic amplitude of the ultrasonic vibration. In addition, within the scope of the polishing process parameters selected by preliminary experiments, ultrasonic amplitude of 2.5μm, polishing force of 0.5N, workpiece feed rate of 5 mm·min-1, polishing wheel rotational speed of 50rpm, polishing time of 35min, abrasive size of 100nm and the polishing liquid concentration of 15% is the best technology of UVAP of micro-structures. Under the optimal parameters, the ground traces on the micro-structured surface were removed efficiently and the integrity of the edges of the micro-structure after grinding was maintained efficiently.

Two-dimensional vibrational-electronic spectroscopy

Science.gov (United States)

Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

2015-10-01

Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

Two-dimensional vibrational-electronic spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

2015-10-21

Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

Vibration produced by hand-held olive electrical harvesters

Directory of Open Access Journals (Sweden)

Emanuele Cerruto

2012-09-01

Full Text Available The paper reports the results of some laboratory and field tests aimed at assessing the acceleration levels transmitted to the hand-arm system by electric portable harvesters for olive. Four harvesting heads, different for shape and kinematic system, and five bars, different for diameter, length and material (aluminium and carbon fibre, were used in assembling eleven harvesters. The vibrations were measured in two points, next to the handgrips. The laboratory tests allowed the evaluation of the acceleration levels in standard controlled conditions, while the field tests allowed the assessing of the effects of the tree canopy with respect to the no load running. The laboratory tests showed that in reducing the vibration level plays a major role the kinematic system of the harvesting head and then the bar material. The classical flap-type harvester produced accelerations of around 20 m/s2, while by using a harvesting head with two parts in opposite movement, the accelerations were lowered to about 6 m/s2. The use of carbon fibres for the bars, besides the reduction in weight, produced also a reduction in acceleration (from 21 to 16 m/s2. The field tests proved that the tree canopy had a negative effect on the vibrations transmitted to the hand-arm system, especially when the aluminium bar of small diameter was used.

Recovering Intrinsic Fragmental Vibrations Using the Generalized Subsystem Vibrational Analysis.

Science.gov (United States)

Tao, Yunwen; Tian, Chuan; Verma, Niraj; Zou, Wenli; Wang, Chao; Cremer, Dieter; Kraka, Elfi

2018-05-08

Normal vibrational modes are generally delocalized over the molecular system, which makes it difficult to assign certain vibrations to specific fragments or functional groups. We introduce a new approach, the Generalized Subsystem Vibrational Analysis (GSVA), to extract the intrinsic fragmental vibrations of any fragment/subsystem from the whole system via the evaluation of the corresponding effective Hessian matrix. The retention of the curvature information with regard to the potential energy surface for the effective Hessian matrix endows our approach with a concrete physical basis and enables the normal vibrational modes of different molecular systems to be legitimately comparable. Furthermore, the intrinsic fragmental vibrations act as a new link between the Konkoli-Cremer local vibrational modes and the normal vibrational modes.

Studying the influence of vibration exposures on digestives system of workers in a food processing company

Directory of Open Access Journals (Sweden)

2012-12-01

Full Text Available Introduction: Today’s, defective and faulty equipments lose a large part of them energy as noise and vibration which beside their financial costs can be hazardous to the health of people. Vibration as a physical agent can cause an adverse health effect on human to nervous system. These effects, based on body region can be as specific or general systems. Digestion system has a natural vibration of 3-8Hz frequency. When the digestive system is exposed by such vibration, it can make impairment on that system. This study aimed to study vibration effect on digestion irregularities. . Material and Method: This was a retrospective case-control study conducted in a food industry. The number of 103 workers digestive problem and 431 healthy workers were selected as population study. Exposure to the vibration in the different parts were measured. People with more than 100 dB was considered exposed group. Then, after determining the number of exposed and non exposed groups, data were analyzed using statistical methodologies. .Result: The acceleration level of vibration was 109.8 dB in the packing section, which was less than standard limit (118.8 dB. Study population had a managed of 24-57 years old with 4-15 years of job tenure. In 59.2% of case comparing to 22.7% of control group were exposed to the vibration. The odds ratio (OR of prevalence rate of digestive problem among exposed group was 6.3 times more than non exposed group people, in risk of gastrointestinal complications. .Conclusion: Beside of the other risk factors of digestive problem, vibration can be also an effective cause of adverse health problem: Even by lower level of digestive problem can be seen in the exposed people. So, we suggest in the workplace with vibration risk factor, a digestive health exam be take general medical beside periodic examination. Moreover, it is recommended that researches related to the vibration is widely developed and the vibration standard limits is revised

Using frequency response functions to manage image degradation from equipment vibration in the Daniel K. Inouye Solar Telescope

Science.gov (United States)

McBride, William R.; McBride, Daniel R.

2016-08-01

The Daniel K Inouye Solar Telescope (DKIST) will be the largest solar telescope in the world, providing a significant increase in the resolution of solar data available to the scientific community. Vibration mitigation is critical in long focal-length telescopes such as the Inouye Solar Telescope, especially when adaptive optics are employed to correct for atmospheric seeing. For this reason, a vibration error budget has been implemented. Initially, the FRFs for the various mounting points of ancillary equipment were estimated using the finite element analysis (FEA) of the telescope structures. FEA analysis is well documented and understood; the focus of this paper is on the methods involved in estimating a set of experimental (measured) transfer functions of the as-built telescope structure for the purpose of vibration management. Techniques to measure low-frequency single-input-single-output (SISO) frequency response functions (FRF) between vibration source locations and image motion on the focal plane are described. The measurement equipment includes an instrumented inertial-mass shaker capable of operation down to 4 Hz along with seismic accelerometers. The measurement of vibration at frequencies below 10 Hz with good signal-to-noise ratio (SNR) requires several noise reduction techniques including high-performance windows, noise-averaging, tracking filters, and spectral estimation. These signal-processing techniques are described in detail.

Development of adaptive helicopter seat systems for aircrew vibration mitigation

Science.gov (United States)

Chen, Yong; Wickramasinghe, Viresh; Zimcik, David G.

2008-03-01

Helicopter aircrews are exposed to high levels of whole body vibration during flight. This paper presents the results of an investigation of adaptive seat mount approaches to reduce helicopter aircrew whole body vibration levels. A flight test was conducted on a four-blade helicopter and showed that the currently used passive seat systems were not able to provide satisfactory protection to the helicopter aircrew in both front-back and vertical directions. Long-term exposure to the measured whole body vibration environment may cause occupational health issues such as spine and neck strain injuries for aircrew. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew body. For proof-of-concept demonstration, a miniature modal shaker was properly aligned between the cabin floor and the seat frame to provide adaptive actuation authority. Adaptive control laws were developed to reduce the vibration transmitted to the aircrew body, especially the helmet location in order to minimize neck and spine injuries. Closed-loop control test have been conducted on a full-scale helicopter seat with a mannequin configuration and a large mechanical shaker was used to provide representative helicopter vibration profiles to the seat frame. Significant vibration reductions to the vertical and front-back vibration modes have been achieved simultaneously, which verified the technical readiness of the adaptive mount approach for full-scale flight test on the vehicle.

RESEARCH OF BRIDGE STRUCTURE VIBRATION CHARACTERISTICS

Directory of Open Access Journals (Sweden)

V.P. Babak

2005-02-01

Full Text Available  Bridge structure test results with using different types of dynamic force have been considered. It has been shown, that the developed technique of registering and processing vibration signals allows obtaining thin spectrum structure. The analysis of its change that is defined by the type of structure loading applied has been carried out. Key parameters of the vibration signals registered have been defined.

Tool vibration detection with eddy current sensors in machining process and computation of stability lobes using fuzzy classifiers

Science.gov (United States)

Devillez, Arnaud; Dudzinski, Daniel

2007-01-01

Today the knowledge of a process is very important for engineers to find optimal combination of control parameters warranting productivity, quality and functioning without defects and failures. In our laboratory, we carry out research in the field of high speed machining with modelling, simulation and experimental approaches. The aim of our investigation is to develop a software allowing the cutting conditions optimisation to limit the number of predictive tests, and the process monitoring to prevent any trouble during machining operations. This software is based on models and experimental data sets which constitute the knowledge of the process. In this paper, we deal with the problem of vibrations occurring during a machining operation. These vibrations may cause some failures and defects to the process, like workpiece surface alteration and rapid tool wear. To measure on line the tool micro-movements, we equipped a lathe with a specific instrumentation using eddy current sensors. Obtained signals were correlated with surface finish and a signal processing algorithm was used to determine if a test is stable or unstable. Then, a fuzzy classification method was proposed to classify the tests in a space defined by the width of cut and the cutting speed. Finally, it was shown that the fuzzy classification takes into account of the measurements incertitude to compute the stability limit or stability lobes of the process.

Rare gas dependence of vibration--vibration energy transfer processes: A diagnostic technique. Applications to CH2D2 and CH3F

International Nuclear Information System (INIS)

Apkarian, V.A.; Weitz, E.

1979-01-01

The rare gas dependence of V--V rates can be used as a diagnostic technique to identify different mechanisms of vibrational energy transfer and determine the rate constants for individual kinetic steps. The method is especially useful for the identification and measurement of rates of resonant vibrational energy transfer processes. Analytical and numerical solutions of pertinent model equations are presented and their range of applicability is discussed. The technique is applied to CH 2 D 2 and CH 3 F. In CH 2 D 2 results of studies on ν 9 , [ν 1 , ν 6 ] and states in the 2000 cm -1 region are presented where the application of the technique has made it possible to identify the pathways leading to population of these states and to assign rate constants to some of the steps involved. In CH 3 F, by studying the Ar dependence of the V--V rates of the [ν 2 , ν 5 ] and [ν 1 , ν 4 ] states it has been possible to construct a complete map of energy transfer pathways which can explain all experimental observations for this system, to date. The general applicability of the technique and its potential application to other systems is also considered

Reducing vibration transfer from power plants by active methods

Science.gov (United States)

Kiryukhin, A. V.; Milman, O. O.; Ptakhin, A. V.

2017-12-01

The possibility of applying the methods of active damping of vibration and pressure pulsations for reducing their transfer from power plants into the environment, the seating, and the industrial premises are considered. The results of experimental works implemented by the authors on the active broadband damping of vibration and dynamic forces after shock-absorption up to 15 dB in the frequency band up to 150 Hz, of water pressure pulsations in the pipeline up to 20 dB in the frequency band up to 600 Hz, and of spatial low-frequency air noise indoors of a diesel generator at discrete frequency up to 20 dB are presented. It is shown that a reduction of vibration transfer through a vibration-isolating junction (expansion joints) of pipelines with liquid is the most complicated and has hardly been developed so far. This problem is essential for vibration isolation of power equipment from the seating and the environment through pipelines with water and steam in the power and transport engineering, shipbuilding, and in oil and gas pipelines in pumping stations. For improving efficiency, reducing the energy consumption, and decreasing the overall dimensions of equipment, it is advisable to combine the work of an active system with passive damping means, the use of which is not always sufficient. The executive component of the systems of active damping should be placed behind the vibration isolators (expansion joints). It is shown that the existence of working medium and connection of vibration with pressure pulsations in existing designs of pipeline expansion joints lead to growth of vibration stiffness of the expansion joint with the environment by two and more orders as compared with the static stiffness and makes difficulties for using the active methods. For active damping of vibration transfer through expansion joints of pipelines with a liquid, it is necessary to develop expansion joint structures with minimal connection of vibrations and pulsations and minimal

Built-up edge investigation in vibration drilling of Al2024-T6.

Science.gov (United States)

Barani, A; Amini, S; Paktinat, H; Fadaei Tehrani, A

2014-07-01

Adding ultrasonic vibrations to drilling process results in an advanced hybrid machining process, entitled "vibration drilling". This study presents the design and fabrication of a vibration drilling tool by which both rotary and vibrating motions are applied to drill simultaneously. High frequency and low amplitude vibrations were generated by an ultrasonic transducer with frequency of 19.65 kHz. Ultrasonic transducer was controlled by a MPI ultrasonic generator with 3 kW power. The drilling tool and workpiece material were HSS two-flute twist drill and Al2024-T6, respectively. The aim of this study was investigating on the effect of ultrasonic vibrations on built-up edge, surface quality, chip morphology and wear mechanisms of drill edges. Therefore, these factors were studied in both vibration and ordinary drilling. Based on the achieved results, vibration drilling offers less built-up edge and better surface quality compared to ordinary drilling. Copyright © 2014 Elsevier B.V. All rights reserved.

Approaches for reducing structural vibration of the carbody railway vehicles

Directory of Open Access Journals (Sweden)

Dumitriu Mădălina

2017-01-01

Full Text Available Reducing the weight of the railway vehicles stands as a decisive rule in their design, entailed by higher velocities, the need to consume less energy and lower the manufacturing costs, along with the maximization of the use of loads on the axle. Once complied with this rule, the vehicle flexibility increases and leads to an easy excitation of the structural vibrations in the carbody, with an impact upon the ride comfort in the railway vehicle. For a better ride comfort in lightweight railway vehicles, both vibration isolation approaches and structural damping approaches have been introduced. The paper herein submits a brief review of the main structural damping approaches aiming to reduce the amplitude in the carbody structural vibrations, based on the use of the piezoelectric elements in passive control schemes. The paper outcomes show the potential of the presented methods concerning the reduction of the flexible vibrations in the carbody and the ride comfort improvement.

Vibration reduction methods and techniques for rotorcraft utilizing on-blade active control, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Rotor blades adapted for vibration control have the added benefit of extended blade and rotor life, as well as improved passenger comfort. Approaches that have been...

Vibration Measurement with PULSE and DSPACE Equipment

Directory of Open Access Journals (Sweden)

Radim KLEČKA

2009-06-01

Full Text Available This contribution describes techniques and results of measurement with TIRA vibration generator. A method of experimental modal analysis allows next restore of vibration data. The goal is check validity of head expanders and screw connection. This process is based to using ME’scope environment. Another goal is check possibilities of dSPACE platform to vibration measurement. This task includes design of connection between dSPACE system and power amplifier, creating of graphical user interface and analyzing main configuration parameters to improve quality of drive signal.

Random Vibration Testing of Advanced Wet Tantalum Capacitors

Science.gov (United States)

Teverovsky, Alexander

2015-01-01

Advanced wet tantalum capacitors allow for improved performance of power supply systems along with substantial reduction of size and weight of the systems that is especially beneficial for space electronics. Due to launch-related stresses, acceptance testing of all space systems includes random vibration test (RVT). However, many types of advanced wet tantalum capacitors cannot pass consistently RVT at conditions specified in MIL-PRF-39006, which impedes their use in space projects. This requires a closer look at the existing requirements, modes and mechanisms of failures, specifics of test conditions, and acceptance criteria. In this work, different lots of advanced wet tantalum capacitors from four manufacturers have been tested at step stress random vibration conditions while their currents were monitored before, during, and after the testing. It has been shown that the robustness of the parts and their reliability are mostly due to effective self-healing processes and limited current spiking or minor scintillations caused by RVT do not increase the risk of failures during operation. A simple model for scintillations events has been used to simulate current spiking during RVT and optimize test conditions. The significance of scintillations and possible effects of gas generation have been discussed and test acceptance criteria for limited current spiking have been suggested.

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....

Coupled Vibration of Unshrouded Centrifugal Compressor Impellers. Part II: Computation of Vibration Behavior

Directory of Open Access Journals (Sweden)

Dirk Hagelstein

2000-01-01

Full Text Available The increased use of small gas turbines and turbochargers in different technical fields has led to the development of highly-loaded centrifugal compressors with extremely thin blades. Due to high rotational speed and the correspondingly high centrifugal loads, the shape of the impeller hub must also be optimized. This has led to a reduction of the thickness of the impeller disc in the outlet region. The thin parts of the impeller are very sensitive and may be damaged by the excitation of dangerous blade vibrations.

Vibrational motions associated with primary processes in bacteriorhodopsin studied by coherent infrared emission spectroscopy.

Science.gov (United States)

Groma, Géza I; Colonna, Anne; Martin, Jean-Louis; Vos, Marten H

2011-03-16

The primary energetic processes driving the functional proton pump of bacteriorhodopsin take place in the form of complex molecular dynamic events after excitation of the retinal chromophore into the Franck-Condon state. These early events include a strong electronic polarization, skeletal stretching, and all-trans-to-13-cis isomerization upon formation of the J intermediate. The effectiveness of the photoreaction is ensured by a conical intersection between the electronic excited and ground states, providing highly nonadiabatic coupling to nuclear motions. Here, we study real-time vibrational coherences associated with these motions by analyzing light-induced infrared emission from oriented purple membranes in the 750-1400 cm(-)(1) region. The experimental technique applied is based on second-order femtosecond difference frequency generation on macroscopically ordered samples that also yield information on phase and direction of the underlying motions. Concerted use of several analysis methods resulted in the isolation and characterization of seven different vibrational modes, assigned as C-C stretches, out-of-plane methyl rocks, and hydrogen out-of-plane wags, whereas no in-plane H rock was found. Based on their lifetimes and several other criteria, we deduce that the majority of the observed modes take place on the potential energy surface of the excited electronic state. In particular, the direction sensitivity provides experimental evidence for large intermediate distortions of the retinal plane during the excited-state isomerization process. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps

Directory of Open Access Journals (Sweden)

Uğbreve;ur Dalli

2011-01-01

Full Text Available An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.

Noise and vibration improvement technologies for engines; Engine ni okeru soon shindo kaizen gijutsu

Energy Technology Data Exchange (ETDEWEB)

Kuzuoka, H.; Maeda, R. [Nissan Motor Co. Ltd., Tokyo (Japan)

1999-02-01

This is an outline of recent measurement and simulation technology for reduction of engine noise and vibration. We can recognize correct phenomenon by visualization of noise and vibration phenomena using new measurement technology. And we can create optimum countermeasures using new simulation technology In this report, examples of application of these technology in the development of NEO-DI engines are provided. (author)

Application of nonliner reduction techniques in chemical process modeling: a review

International Nuclear Information System (INIS)

Muhaimin, Z; Aziz, N.; Abd Shukor, S.R.

2006-01-01

Model reduction techniques have been used widely in engineering fields for electrical, mechanical as well as chemical engineering. The basic idea of reduction technique is to replace the original system by an approximating system with much smaller state-space dimension. A reduced order model is more beneficial to process and industrial field in terms of control purposes. This paper is to provide a review on application of nonlinear reduction techniques in chemical processes. The advantages and disadvantages of each technique reviewed are also highlighted

Evidence of impaired learning during whole-body vibration

Science.gov (United States)

Sherwood, N.; Griffin, M. J.

1992-01-01

A study of the effects of whole-body vibration on learning and memory was conducted, in which a context-dependent experimental design was used. Forty subjects completed a simple associative learning task, half during exposure to 16 Hz whole-body sinusoidal vertical vibration at 2.0 m s -2 r.m.s. and half while static. The results show that the rates of learning of the two groups differed, with that of the vibrated subjects significantly impaired. A second session, one week later, indicated that information learnt in one vibration environment could be recalled equally well in a different environment, suggesting no context-dependent effects on memory processes.

PC based vibration monitoring system

International Nuclear Information System (INIS)

Jain, Sanjay K.; Roy, D.A.; Pithawa, C.K.; Patil, R.K.

2004-01-01

Health of large rotating machinery gets reflected in the vibration signature of the rotor and supporting structures and proper recording of these signals and their analysis can give a clear picture of the health of the machine. Using these data and their trending, it is possible to predict an impending trouble in the machine so that preventive action can be taken in time and catastrophic failure can be avoided. Continuous monitoring and analysis can give quick warning and enable operator to take preventive measures. Reactor Control Division, BARC is developing a PC based Vibration monitoring system for turbo generator machinery. The System can acquire 20 vibration signals at a rate of 5000 samples per second and also 15 process signals at a rate of 100 samples/ sec. The software for vibration monitoring system includes acquisition modules, analysis modules and Graphical User Interface module. The acquisition module involves initialization, setting of required parameters and acquiring the data from PC-based data acquisition cards. The acquired raw vibration data is then stored for analysis using various software packages. The display and analysis of acquired data is done in LabVIEW 7.0 where the data is displayed in time as well as frequency domain along with the RMS value of the signal. (author)

Vibrational-rotational relaxation of the simplest hydrogen-containing molecules (review)

International Nuclear Information System (INIS)

Molevich, N.E.; Oraevskii, A.N.

1987-01-01

In connection with the development of chemical lasers much attention is now devoted to the study of kinetic processes is gaseous mixtures containing the hydrogen halides. Vibrational relaxation of molecules if primarily studied without specifying its relation to the rational levels. Rotational relaxation is regarded a priori as faster than vibrational relaxation, so that the population of the rotational levels is assumed to be in equilibrium. This approach to the relaxation of hydrogen halide molecules (and other diatomic hydrogen-containing molecules), however, is unable to explain satisfactorily the results of the papers discussed below. An analysis of the data obtained in these papers leads to the conclusion that the general picture of relaxation in diatomic hydrogen-containing molecules must be viewed as a unified process of vibrational and rotational relaxation. It is shown that those effects observed during vibrational relaxation of such molecules which are unusual from the standpoint of the theory of vibrational-translational relaxation are well explained in terms of intermolecular vibrational-rotational relaxation together with pure rotational relaxation

Vibration of imperfect rotating disk

Directory of Open Access Journals (Sweden)

Půst L.

2011-12-01

Full Text Available This study is concerned with the theoretical and numerical calculations of the flexural vibrations of a bladed disk. The main focus of this study is to elaborate the basic background for diagnostic and identification methods for ascertaining the main properties of the real structure or an experimental model of turbine disks. The reduction of undesirable vibrations of blades is proposed by using damping heads, which on the experimental model of turbine disk are applied only on a limited number of blades. This partial setting of damping heads introduces imperfection in mass, stiffness and damping distribution on the periphery and leads to more complicated dynamic properties than those of a perfect disk. Calculation of FEM model and analytic—numerical solution of disk behaviour in the limited (two modes frequency range shows the splitting of resonance with an increasing speed of disk rotation. The spectrum of resonance is twice denser than that of a perfect disk.

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...

Effects of nuclear vibration on the ionization process of H2+ in ultrashort intense laser field

International Nuclear Information System (INIS)

Phan, Ngoc-Loan; Nguyen, Ngoc-Ty; Truong, Tran-Chau

2015-01-01

By numerically solving the time-dependent Schrödinger equation, we calculate the ionization probability of a vibrating H 2 + exposed to ultrashort intense laser fields. The results show that the ionization probability increases by time and gets a saturation value. We also find that with some first vibration levels, the ionization probability from a higher vibration level is larger than that from a lower one. However, with higher vibration levels, at a certain level the ionization probability will take maximum and decrease with next levels. (paper)

Review on the processes of reduction and refining of metallic vanadium

International Nuclear Information System (INIS)

Mourao, M.B.; Capocchi, J.D.T.

1982-01-01

A literature survey on the processes of vanadium reduction and refining is presented. The results achieved by several research workers are comented. Enphasis is given to the aluminothermic reduction of V 2 O 5 followed by purification of the crude metal in an electron beam melting furnace or by high temperature molten salts electrolitic processes. (Author) [pt

Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps

OpenAIRE

Dalli, Uğbreve;ur; Yüksel, Şcedilefaatdin

2011-01-01

An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing condit...

An advanced purex process based on salt-free reductants

Energy Technology Data Exchange (ETDEWEB)

He, Hui; Ye, Guoan; Tang, Hongbin; Zheng, Weifang; Li, Gaoliang; Lin, Rushan [China Institute of Atomic Energy, Beijing (China). Dept. of Radiochemistry

2014-04-01

An advanced plutonium and uranium recovery process has been established based on two organic reductants, N,N-dimethylhydroxylamine (DMHAN) and methylhydrazine (MH), as U/Pu separation reagents. This Advanced Purex process based on Organic Reductants (APOR) is composed of three cycles, including U/Pu co-decontamination/separation cycle, uranium purification cycle and plutonium purification cycle. Using DMHAN and MH as plutonium stripping reagents in the U/Pu co-decontamination/separation cycle and plutonium purification cycle, the APOR process exhibits high performance with following highlights: (1) the process is much simpler because of the elimination of Tc scrubbing operation and the supplement extraction operation, (2) high efficiency of U/Pu separation can be achieved in the first cycle, (3) plutonium product solution of high concentration can be obtained in the Pu purification cycle with a simple extraction operation instead of circumfluent extraction or evaporation of the plutonium solution. (orig.)

Vibration isolation using nonlinear damping implemented by a feedback-controlled MR damper

International Nuclear Information System (INIS)

Ho, C; Lang, Z Q; Billings, S A; Sapiński, B

2013-01-01

The main problem of using a conventional linear damper on a vibration isolation system is that the reduction of the resonant peak in many cases inevitably results in the degradation of the high-frequency transmissibility. Instead of using active control methods which normally depend on the model of the controlled plant and where unmodelled dynamics may induce stability concerns, recent studies have revealed that optimal vibration isolation over a wide frequency range can be achieved by using nonlinear damping. The present study is concerned with the realization of the ideal nonlinear damping characteristic using a feedback-controlled MR damper. Both simulation and experimental studies are conducted to demonstrate the advantages of the simple but effective vibration control strategy. This research work has significant implications for the effective use of MR dampers in the vibration control of a wide range of engineering systems. (paper)

Development of reduction technology for oxide fuel. Behaviour of rare-earth in lithium reduction process

International Nuclear Information System (INIS)

Kato, Tetsuya; Usami, Tsuyoshi; Yuda, Ryoichi; Kurata, Masateru; Moriyama, Hirotake

2000-01-01

Solubility measurements of rare-earth oxides in molten LiCl-Li 2 O salt and reduction tests of UO 2 doped with rare-earth oxides were carried out to determine the behavior of rare-earths in lithium reduction process. The solubility of rare-earth oxides increases in the order of Gd 2 O concentration. In multi-element systems including 6 rare-earth oxides, the solubility of each element is smaller than that in the individual systems. In the reduction tests, more than 90% of UO 2 was reduced within 1 hour after starting reduction and about 7% of rare-earths eluded into the LiCl molten salt bath containing Li 2 O which is formed by the reduction of UO 2 . The rare-earth concentrations in the bath were evaluated using the solubility data, assuming that rare-earth oxides in multi-element systems form solid solution as the equilibrium solid phase and that the activity coefficients in the solid phase are independent of the compositions. The calculated concentrations are consistent with the experimental ones obtained in the reduction tests. (author)

Evaluating the transmitted vibration to operator′s hands hand and effect of protective gloves in real condition, based on International Standard Organization 5349 standard

Directory of Open Access Journals (Sweden)

Farhad Forouharmajd

2016-01-01

Full Text Available Aims: The objective of this research was an evaluation of hand-held tools vibration acceleration such as circular saw and drill transmitted to operator′s and also to determine the role of glove in vibration reduction of those tools. Materials and Methods: In this study, Bruel and Kjaer Vibration meter with a model of 2231 and its analyzer, 2522, along three types of gloves have been used. Accelerometer transducer installed according to International Standard Organization (ISO 5349:1-2 standards in the case of the operator handles the hand-held tool. In next step, the transducer was placed inside the glove. Results: The results show the most accelerated vibration in axis Y for circular saw while working on Plexiglas. All of the used gloves show a reduction of vibration transmission from tools to hands. Glove of C grouped had a reduction of vibration less than two other groups. Conclusion: Based on ISO 5349-1, 10% of workers who are working with circular saw and drill without using glove will be affiliated to white finger after about 7-12 years. As a whole, the results showed that the anti-vibration gloves should be tested in real conditions before using them.

Noise and vibration in friction systems

CERN Document Server

Sergienko, Vladimir P

2015-01-01

The book analyzes the basic problems of oscillation processes and theoretical aspects of noise and vibration in friction systems. It presents generalized information available in literature data and results of the authors in vibroacoustics of friction joints, including car brakes and transmissions. The authors consider the main approaches to abatement of noise and vibration in non-stationary friction processes. Special attention is paid to materials science aspects, in particular to advanced composite materials used to improve the vibroacoustic characteristics of tribopairs The book is intended for researchers and technicians, students and post-graduates specializing in mechanical engineering, maintenance of machines and transport means, production certification, problems of friction and vibroacoustics.

Vibration mixer

Energy Technology Data Exchange (ETDEWEB)

Alekhin, S.A.; Chernov, V.S.; Denisenko, V.V.; Gorodnyanskiy, I.F.; Prokopov, L.I.; Tikhonov, Yu.P.

1983-01-01

The vibration mixer is proposed which contains a housing, vibration drive with rod installed in the upper part of the mixing mechanism made in the form of a hollow shaft with blades. In order to improve intensity of mixing and dispersion of the mud, the shaft with the blades is arranged on the rod of the vibrator and is equipped with a cam coupling whose drive disc is attached to the vibration rod. The rod is made helical, while the drive disc of the cam coupling is attached to the helical surface of the rod. In addition, the vibration mixer is equipped with perforated discs installed on the ends of the rods.

Photocatalytic Graphene-TiO2 Thin Films Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray Coating in a Sol-Gel Process

Directory of Open Access Journals (Sweden)

Fatemeh Zabihi

2017-05-01

Full Text Available In this work, we communicate a facile and low temperature synthesis process for the fabrication of graphene-TiO2 photocatalytic composite thin films. A sol-gel chemical route is used to synthesize TiO2 from the precursor solutions and spin and spray coating are used to deposit the films. Excitation of the wet films during the casting process by ultrasonic vibration favorably influences both the sol-gel route and the deposition process, through the following mechanisms. The ultrasound energy imparted to the wet film breaks down the physical bonds of the gel phase. As a result, only a low-temperature post annealing process is required to eliminate the residues to complete the conversion of precursors to TiO2. In addition, ultrasonic vibration creates a nanoscale agitating motion or microstreaming in the liquid film that facilitates mixing of TiO2 and graphene nanosheets. The films made based on the above-mentioned ultrasonic vibration-assisted method and annealed at 150 °C contain both rutile and anatase phases of TiO2, which is the most favorable configuration for photocatalytic applications. The photoinduced and photocatalytic experiments demonstrate effective photocurrent generation and elimination of pollutants by graphene-TiO2 composite thin films fabricated via scalable spray coating and mild temperature processing, the results of which are comparable with those made using lab-scale and energy-intensive processes.

Occupational Noise Reduction in CNC Striping Process

Science.gov (United States)

Mahmad Khairai, Kamarulzaman; Shamime Salleh, Nurul; Razlan Yusoff, Ahmad

2018-03-01

Occupational noise hearing loss with high level exposure is common occupational hazards. In CNC striping process, employee that exposed to high noise level for a long time as 8-hour contributes to hearing loss, create physical and psychological stress that reduce productivity. In this paper, CNC stripping process with high level noises are measured and reduced to the permissible noise exposure. First condition is all machines shutting down and second condition when all CNC machine under operations. For both conditions, noise exposures were measured to evaluate the noise problems and sources. After improvement made, the noise exposures were measured to evaluate the effectiveness of reduction. The initial average noise level at the first condition is 95.797 dB (A). After the pneumatic system with leakage was solved, the noise reduced to 55.517 dB (A). The average noise level at the second condition is 109.340 dB (A). After six machines were gathered at one area and cover that area with plastic curtain, the noise reduced to 95.209 dB (A). In conclusion, the noise level exposure in CNC striping machine is high and exceed the permissible noise exposure can be reduced to acceptable levels. The reduction of noise level in CNC striping processes enhanced productivity in the industry.

Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

Science.gov (United States)

Zhang, Zhengyi; Liu, Chuntong; Li, Hongcai; He, Zhenxin; Zhao, Xiaofeng

2017-06-01

In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

Customized DSP-based vibration measurement for wind turbines

Energy Technology Data Exchange (ETDEWEB)

LaWhite, N.E.; Cohn, K.E. [Second Wind Inc., Somerville, MA (United States)

1996-12-31

As part of its Advanced Distributed Monitoring System (ADMS) project funded by NREL, Second Wind Inc. is developing a new vibration measurement system for use with wind turbines. The system uses low-cost accelerometers originally designed for automobile airbag crash-detection coupled with new software executed on a Digital Signal Processor (DSP) device. The system is envisioned as a means to monitor the mechanical {open_quotes}health{close_quotes} of the wind turbine over its lifetime. In addition the system holds promise as a customized emergency vibration detector. The two goals are very different and it is expected that different software programs will be executed for each function. While a fast Fourier transform (FFT) signature under given operating conditions can yield much information regarding turbine condition, the sampling period and processing requirements make it inappropriate for emergency condition monitoring. This paper briefly reviews the development of prototype DSP and accelerometer hardware. More importantly, it reviews our work to design prototype vibration alarm filters. Two-axis accelerometer test data from the experimental FloWind vertical axis wind turbine is analyzed and used as a development guide. Two levels of signal processing are considered. The first uses narrow band pre-processing filters at key fundamental frequencies such as the 1P, 2P and 3P. The total vibration energy in each frequency band is calculated and evaluated as a possible alarm trigger. In the second level of signal processing, the total vibration energy in each frequency band is further decomposed using the two-axis directional information. Directional statistics are calculated to differentiate between linear translations and circular translations. After analyzing the acceleration statistics for normal and unusual operating conditions, the acceleration processing system described could be used in automatic early detection of fault conditions. 9 figs.

Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process.

Science.gov (United States)

Moussavi, Gholamreza; Shekoohiyan, Sakine

2016-11-15

This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N2 selectivity achieved at HRT of 80min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasonic Low-Friction Containment Plate for Thermal and Ultrasonic Stir Weld Processes

Science.gov (United States)

Graff, Karl; Short, Matt

2013-01-01

The thermal stir welding (TSW) process is finding applications in fabrication of space vehicles. In this process, workpieces to be joined by TSW are drawn, by heavy forces, between "containment plates," past the TSW tool that then causes joining of the separate plates. It is believed that the TSW process would be significantly improved by reducing the draw force, and that this could be achieved by reducing the friction forces between the workpieces and containment plates. Based on use of high-power ultrasonics in metal forming processes, where friction reduction in drawing dies has been achieved, it is believed that ultrasonic vibrations of the containment plates could achieve similar friction reduction in the TSW process. By applying ultrasonic vibrations to the containment plates in a longitudinal vibration mode, as well as by mounting and holding the containment plates in a specific manner such as to permit the plates to acoustically float, friction between the metal parts and the containment plates is greatly reduced, and so is the drawing force. The concept was to bring in the ultrasonics from the sides of the plates, permitting the ultrasonic hardware to be placed to the side, away from the equipment that contains the thermal stir tooling and that applies clamping forces to the plates. Tests demonstrated that one of the major objectives of applying ultrasonics to the thermal stir system, that of reducing draw force friction, should be achievable on a scaled-up system.

State resolved vibrational relaxation modeling for strongly nonequilibrium flows

Science.gov (United States)

Boyd, Iain D.; Josyula, Eswar

2011-05-01

Vibrational relaxation is an important physical process in hypersonic flows. Activation of the vibrational mode affects the fundamental thermodynamic properties and finite rate relaxation can reduce the degree of dissociation of a gas. Low fidelity models of vibrational activation employ a relaxation time to capture the process at a macroscopic level. High fidelity, state-resolved models have been developed for use in continuum gas dynamics simulations based on computational fluid dynamics (CFD). By comparison, such models are not as common for use with the direct simulation Monte Carlo (DSMC) method. In this study, a high fidelity, state-resolved vibrational relaxation model is developed for the DSMC technique. The model is based on the forced harmonic oscillator approach in which multi-quantum transitions may become dominant at high temperature. Results obtained for integrated rate coefficients from the DSMC model are consistent with the corresponding CFD model. Comparison of relaxation results obtained with the high-fidelity DSMC model shows significantly less excitation of upper vibrational levels in comparison to the standard, lower fidelity DSMC vibrational relaxation model. Application of the new DSMC model to a Mach 7 normal shock wave in carbon monoxide provides better agreement with experimental measurements than the standard DSMC relaxation model.

Effect of nonlinearity of connecting dampers on vibration control of connected building structures

Directory of Open Access Journals (Sweden)

Masatoshi eKasagi

2016-01-01

Full Text Available The connection of two building structures with dampers is one of effective vibration control systems. In this vibration control system, both buildings have to possess different vibration properties in order to provide a higher vibration reduction performance. In addition to such condition of different vibration properties of both buildings, the connecting dampers also play an important role in the vibration control mechanism. In this paper, the effect of nonlinearity of connecting dampers on the vibration control of connected building structures is investigated in detail. A high-damping rubber damper and an oil damper with and without relief mechanism are treated. It is shown that, while the high-damping rubber damper is effective in a rather small deformation level, the linear oil damper is effective in a relatively large deformation level. It is further shown that, while the oil dampers reduce the response in the same phase as the case without dampers, the high-damping rubber dampers change the phase. The merit is that the high-damping rubber can reduce the damper deformation and keep the sufficient space between both buildings. This can mitigate the risk of building pounding.

An innovative MRE absorber with double natural frequencies for wide frequency bandwidth vibration absorption

International Nuclear Information System (INIS)

Sun, Shuaishuai; Yang, Jian; Li, Weihua; Alici, Gursel; Deng, Huaxia; Du, Haiping; Yan, Tianhong

2016-01-01

A new design of adaptive tuned vibration absorber was proposed in this study for vibration reduction. The innovation of the new absorber is the adoption of the eccentric mass on the top of the multilayered magnetorheological elastomer (MRE) structure so that this proposed absorber has two vibration modes: one in the torsional direction and the other in translational direction. This property enables the absorber to expand its effective bandwidth and to be more capable of reducing the vibrations especially dealing with those vibrations with multi-frequencies. The innovative MRE absorber was designed and tested on a horizontal vibration table. The test results illustrate that the MRE absorber realized double natural frequencies, both of which are controllable. Inertia’s influence on the dynamic behavior of the absorber is also investigated in order to guide the design of the innovative MRE absorber. Additionally, the experimentally obtained natural frequencies coincide with the theoretical data, which sufficiently verifies the feasibility of this new design. The last part in terms of the vibration absorption ability also proves that both of these two natural frequencies play a great role in absorbing vibration energy. (paper)

Videometrics-based Detection of Vibration Linearity in MEMS Gyroscope

Directory of Open Access Journals (Sweden)

Yong Zhou

2011-05-01

Full Text Available MEMS gyroscope performs as a sort of sensor to detect angular velocity, with diverse applications in engineering including vehicle and intelligent traffic etc. A balanced vibration of driving module excited by electrostatic driving signal is the base MEMS gyroscope's performance. In order to analyze the linear property of vibration in MEMS Gyroscope, a method of computer vision measuring is applied with the help of high-speed vidicon to obtain video of linear vibration of driving module in gyroscope, under the driving voltage signal of inherent frequency and amplitude linearly increasing. By means of image processing, target identifying, and motion parameter extracting from the obtained video, vibration curve with time variation is acquired. And then, linearity of this vibration system can be analyzed by focusing on the amplitude value of vibration responding to the amplitude variation of driving voltage signal.

Resonant vibration control of wind turbine blades

DEFF Research Database (Denmark)

Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker

2010-01-01

. The efficiency of the resonant controller is demonstrated for a representative turbine blade exposed to turbulent wind loading. It is found that the present explicit tuning procedure yields close to optimal tuning, with very limited modal spill-over and effective reduction of the vibration amplitudes.......The paper deals with introduction of damping to specific vibration modes of wind turbine blades, using a resonant controller with acceleration feedback. The wind turbine blade is represented by three-dimensional, two-node finite elements in a local, rotating frame of reference. The element...... formulation accounts for arbitrary mass density distributions, general elastic crosssection properties and geometric stiffness effects due to internal stresses. A compact, linear formulation for aerodynamic forces with associated stiffness and damping terms is established and added to the structural model...

Design and fabrication of an energy-harvesting device using vibration absorber

Science.gov (United States)

Heidari, Hamidreza; Afifi, Arash

2017-05-01

Energy-harvesting devices collect energy that is being wasted and convert to the electrical energy. For this reason, this type of devices is considered as a convenient alternative to traditional batteries. In this paper, experimental examinations were performed to investigate the application of harvesting device for the reduction of the vibration amplitude in a vibration system and also increase the efficiency of energy-harvesting device. This study focuses on the energy-harvesting device as both producing electrical device and a vibration disabled absorber. In this regard, a motion-based energy-harvesting device is designed to produce electrical energy and also eliminate vibrations of a two joint-end beam which is located under the harmonic excitation force. Then, the governing equations of the forced motion on the main beam are derived and energy-harvesting system are simulated. In addition, the system designed by MATLAB simulation is explained and its results are expressed. Finally, a prototype of the system was made and the ability of the energy-harvesting device to absorb the original system vibrations, as well as parameters impact on the efficiency of energy harvesting is investigated. Experimental results show that the energy-harvesting device, in addition to producing electric current with a maximum value of 1.5V, reduces 94% of the original system vibrations.

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

Space shuttle main engine vibration data base

Science.gov (United States)

Lewallen, Pat

1986-01-01

The Space Shuttle Main Engine Vibration Data Base is described. Included is a detailed description of the data base components, the data acquisition process, the more sophisticated software routines, and the future data acquisition methods. Several figures and plots are provided to illustrate the various output formats accessible to the user. The numerous vibration data recall and analysis capabilities available through automated data base techniques are revealed.

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

Theory of vibration protection

CERN Document Server

Karnovsky, Igor A

2016-01-01

This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

Vibrotactile Identification of Signal-Processed Sounds from Environmental Events Presented by a Portable Vibrator: A Laboratory Study

Directory of Open Access Journals (Sweden)

Parivash Ranjbar

2008-09-01

Full Text Available Objectives: To evaluate different signal-processing algorithms for tactile identification of environmental sounds in a monitoring aid for the deafblind. Two men and three women, sensorineurally deaf or profoundly hearing impaired with experience of vibratory experiments, age 22-36 years. Methods: A closed set of 45 representative environmental sounds were processed using two transposing (TRHA, TR1/3 and three modulating algorithms (AM, AMFM, AMMC and presented as tactile stimuli using a portable vibrator in three experiments. The algorithms TRHA, TR1/3, AMFM and AMMC had two alternatives (with and without adaption to vibratory thresholds. In Exp. 1, the sounds were preprocessed and directly fed to the vibrator. In Exp. 2 and 3, the sounds were presented in an acoustic test room, without or with background noise (SNR=+5 dB, and processed in real time. Results: In Exp. 1, Algorithm AMFM and AMFM(A consistently had the lowest identification scores, and were thus excluded in Exp. 2 and 3. TRHA, AM, AMMC, and AMMC(A showed comparable identification scores (30%-42% and the addition of noise did not deteriorate the performance. Discussion: Algorithm TRHA, AM, AMMC, and AMMC(A showed good performance in all three experiments and were robust in noise they can therefore be used in further testing in real environments.

Vibration of machine

International Nuclear Information System (INIS)

Kwak, Mun Gyu; Na, Sung Su; Baek, Gwang Hyeon; Song, Chul Gi; Han, Sang Bo

2001-09-01

This book deals with vibration of machine which gives descriptions of free vibration using SDOF system, forced vibration using SDOF system, vibration of multi-degree of freedom system like introduction and normal form, distribution system such as introduction, free vibration of bar and practice problem, approximate solution like lumped approximations and Raleigh's quotient, engineering by intuition and experience, real problem and experimental method such as technology of signal, fourier transform analysis, frequency analysis and sensor and actuator.

Structural dynamics and vibration 1995. PD-Volume 70

International Nuclear Information System (INIS)

Ovunc, B.A.; Esat, I.I.; Sabir, A.B.; Karadag, V.

1995-01-01

The themes of this symposium focused on: dynamic responses to temperature cycles and wind excitation; the influence of the hydraulic feedback on stability; structural reliability; vibratory stress relief; fault detection by signal processing; dynamic contact in mechanisms; vibration of thick flexible mechanisms; higher order mechanisms in flexible mechanisms; natural circular frequencies by finite element method; elastic buckling, stability, and vibration of linear and nonlinear structures; buckling of stiffened plates and rings; mixed variable optimization; vibration optimization; and optimization in a constrained space. Separate abstracts were prepared for 20 papers in this book

Efficient forced vibration reanalysis method for rotating electric machines

Science.gov (United States)

Saito, Akira; Suzuki, Hiromitsu; Kuroishi, Masakatsu; Nakai, Hideo

2015-01-01

Rotating electric machines are subject to forced vibration by magnetic force excitation with wide-band frequency spectrum that are dependent on the operating conditions. Therefore, when designing the electric machines, it is inevitable to compute the vibration response of the machines at various operating conditions efficiently and accurately. This paper presents an efficient frequency-domain vibration analysis method for the electric machines. The method enables the efficient re-analysis of the vibration response of electric machines at various operating conditions without the necessity to re-compute the harmonic response by finite element analyses. Theoretical background of the proposed method is provided, which is based on the modal reduction of the magnetic force excitation by a set of amplitude-modulated standing-waves. The method is applied to the forced response vibration of the interior permanent magnet motor at a fixed operating condition. The results computed by the proposed method agree very well with those computed by the conventional harmonic response analysis by the FEA. The proposed method is then applied to the spin-up test condition to demonstrate its applicability to various operating conditions. It is observed that the proposed method can successfully be applied to the spin-up test conditions, and the measured dominant frequency peaks in the frequency response can be well captured by the proposed approach.

Vibration signature analysis of compressors in the gaseous diffusion process for uranium enrichment

International Nuclear Information System (INIS)

Harbarger, W.B.

1975-01-01

Continuous operation of several thousand axial-flow and centrifugal compressors is vital to the gaseous diffusion process for uranium enrichment. Vibration signature analysis using a minicomputer-based Fast Fourier Transform Analyzer is being applied to the evaluation and surveillance of compressor performance at the Portsmouth Gaseous Diffusion Plant. Three areas of application include: (1) new blade design and prototype compressor evaluation; (2) corrective and preventive maintenance of machinery components; and (3) evaluation of machinery health. The present system is being used to monitor signals from accelerometers mounted on the load-bearing housings of 16 on-line compressors. These signals are transmitted by hard-wire to the analyzer for daily monitoring. A program for expansion of this system to monitor more than a thousand compressors and automation of the signature comparison process is planned for all three gaseous diffusion plants operated for the United States Energy Research and Development Administration. (auth)

Advanced Engine Health Management Applications of the SSME Real-Time Vibration Monitoring System

Science.gov (United States)

Fiorucci, Tony R.; Lakin, David R., II; Reynolds, Tracy D.; Turner, James E. (Technical Monitor)

2000-01-01

The Real Time Vibration Monitoring System (RTVMS) is a 32-channel high speed vibration data acquisition and processing system developed at Marshall Space Flight Center (MSFC). It Delivers sample rates as high as 51,200 samples/second per channel and performs Fast Fourier Transform (FFT) processing via on-board digital signal processing (DSP) chips in a real-time format. Advanced engine health assessment is achieved by utilizing the vibration spectra to provide accurate sensor validation and enhanced engine vibration redlines. Discrete spectral signatures (such as synchronous) that are indicators of imminent failure can be assessed and utilized to mitigate catastrophic engine failures- a first in rocket engine health assessment. This paper is presented in viewgraph form.

Kinetic model of vibrational relaxation in a humid-air pulsed corona discharge

International Nuclear Information System (INIS)

Komuro, Atsushi; Ono, Ryo; Oda, Tetsuji

2010-01-01

The effect of humidity on the vibrational relaxation of O 2 (v) and N 2 (v) in a humid-air pulsed corona discharge is studied using a kinetic model. We previously showed that humidity markedly increases the vibration-to-translation (V-T) rate of molecules in a humid-air pulsed corona discharge by measuring O 2 (v) density (Ono et al 2010 Plasma Sources Sci. Technol. 19 015009). In this paper, we numerically calculate the vibrational kinetics of O 2 , N 2 and H 2 O to study the reason behind the acceleration of V-T in the presence of humidity. The calculation closely reproduces the measured acceleration of V-T due to humidity, and shows that the increase in the V-T rate is caused by the fast vibration-to-vibration (V-V) processes of O 2 -H 2 O and N 2 -H 2 O and the subsequent rapid V-T process of H 2 O-H 2 O. In addition, it is shown that O atom density is also important in the vibrational kinetics owing to the rapid V-T process of O 2 -O.

Data interpolation for vibration diagnostics using two-variable correlations

International Nuclear Information System (INIS)

Branagan, L.

1991-01-01

This paper reports that effective machinery vibration diagnostics require a clear differentiation between normal vibration changes caused by plant process conditions and those caused by degradation. The normal relationship between vibration and a process parameter can be quantified by developing the appropriate correlation. The differences in data acquisition requirements between dynamic signals (vibration spectra) and static signals (pressure, temperature, etc.) result in asynchronous data acquisition; the development of any correlation must then be based on some form of interpolated data. This interpolation can reproduce or distort the original measured quantity depending on the characteristics of the data and the interpolation technique. Relevant data characteristics, such as acquisition times, collection cycle times, compression method, storage rate, and the slew rate of the measured variable, are dependent both on the data handling and on the measured variable. Linear and staircase interpolation, along with the use of clustering and filtering, provide the necessary options to develop accurate correlations. The examples illustrate the appropriate application of these options

Reduction of low frequency vibration of truck driver and seating system through system parameter identification, sensitivity analysis and active control

Science.gov (United States)

Wang, Xu; Bi, Fengrong; Du, Haiping

2018-05-01

This paper aims to develop an 5-degree-of-freedom driver and seating system model for optimal vibration control. A new method for identification of the driver seating system parameters from experimental vibration measurement has been developed. The parameter sensitivity analysis has been conducted considering the random excitation frequency and system parameter uncertainty. The most and least sensitive system parameters for the transmissibility ratio have been identified. The optimised PID controllers have been developed to reduce the driver's body vibration.

Optimal reduction of flexible dynamic system

International Nuclear Information System (INIS)

Jankovic, J.

1994-01-01

Dynamic system reduction is basic procedure in various problems of active control synthesis of flexible structures. In this paper is presented direct method for system reduction by explicit extraction of modes included in reduced model form. Criterion for optimal system discrete approximation in synthesis reduced dynamic model is also presented. Subjected method of system decomposition is discussed in relation to the Schur method of solving matrix algebraic Riccati equation as condition for system reduction. By using exposed method procedure of flexible system reduction in addition with corresponding example is presented. Shown procedure is powerful in problems of active control synthesis of flexible system vibrations

Seismic isolation floor and vibration control equipment for nuclear power plant

International Nuclear Information System (INIS)

Niwa, H.; Fujimoto, S.; Aida, Y.; Miyano, H.

1996-01-01

We have developed a seismic isolation floor to improve protection against earthquakes for process computer systems, and a magnetic dynamic damper to reduce the mechanical vibrations of piping systems and pumps in nuclear power plants. Seismic excitation tests of the seismic isolation floor, on which process computer systems were installed, were performed using large earthquake simulators. The test results proved that the seismic isolation floor significantly reduced seismic forces. To control mechanical vibrations, a magnetic dynamic damper was designed using permanent magnets. This magnetic dynamic damper does not require mechanical springs, dampers and supports in the floors and walls of the building. Vibration tests using a rotating machine model confirmed that the magnetic dynamic damper effectively controlled vibrations in such a rotating machine model. (author)

Dynamic Analysis of an Office Building due to Vibration from Road Construction Activities

Science.gov (United States)

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

2018-04-01

Construction activities are widely known as one of the predominant sources of man-made vibrations that able to create nuisance towards any adjacent building, and this includes the road construction operations. Few studies conclude the construction-induced vibration may be harmful directly and indirectly towards the neighbouring building. This lead to the awareness of study the building vibration response of concrete masonry load bearing system and its vibrational performance towards the road construction activities. This study will simulate multi-storey office building of Sekolah Menengah Kebangsaan (SMK) Bandar Enstek at Negeri Sembilan by using finite element vibration analyses. The excitation of transient loads from ground borne vibrations which triggered by the road construction activities are modelled into the building. The vibration response was recorded during in-situ ambient vibration test by using Laser Doppler Vibrometer (LDV), which specifically performed on four different locations. The finite element simulation process was developed in the commercial FEA software ABAQUS. Then, the experimental data was processed and evaluated in MATLAB ModalV to assess the vibration criteria of the floor in building. As a result, the vibration level of floor in building is fall under VC-E curve which was under the maximum permissible level for office building (VC-ISO). The vibration level on floor is acceptable within the limit that have been referred.

Energy consumption in smelting reduction (SR) processes

International Nuclear Information System (INIS)

Assis, Paulo Santos; Salierno, Giovanni Felice; Fang, Jue; Mankhand, Tilak R.; Assis, Carlos Frederico Campos de

2010-01-01

In contrast, conventional processes use coke and hematite/sinter in the blast furnace, in SR processes, other alternative fuels and iron ore sources, like charcoal and fine iron ores, can be used to produce sponge iron. The use of these alternative sources, by SR processes, can reduce environmental impacts and lower production costs. At first, the concepts of the theoretical gas utilization ratio, the smelting heat of the iron ore and the effective calorific value of coal were introduced. Then, the reason for gas utilization ratio and its performance in the shaft as a reducer in the smelting process are discussed and calculated. The relationship between coal consumption and iron ore reduction in the fluidized bed are also discussed. Finally, the influence of post-combustion on coal consumption in an iron bath furnace are calculated and discussed. (author)

Vibrational excitation in a hydrogen volume source

International Nuclear Information System (INIS)

Eenshuistra, P.J.

1989-01-01

In this thesis the complex of processes which determines the D - or H - density in a volume source, a hydrogen discharge, is studied. D - beams are of interest for driving the current of a fusion plasma in a TOKAMAK. Densities of vibrationally excited molecules, of H atoms, and of metastable hydrogen molecules were determined using Resonance-Enhanced MultiPhoton Ionization (REMPI). An experiment in which vibrationally highly excited molecules are formed by recombination of atoms in a cold metal surface, is described. The production and destruction of vibrationally excited molecules and atoms in the discharge is discussed. The vibrational distribution for 3≤ν≤5 (ν = vibrational quantumnumber) is strongly super-thermal. This effect is more apparent at higher discharge current and lower gas pressure. The analysis with a model based on rate equations, which molecules are predominantly produced by primary electron excitation of hydrogen molecules and deexcited upon one wall collision. The atom production is compatible with dissociation of molecules by primary electrons, dissociation of molecules on the filaments, and collisions between positive ions and electrons. The electrons are predominantly destroyed by recombination on the walls. Finally the production and destruction of H - in the discharge are discussed. The density of H - in the plasma, the electron density and temperature were determined. H - extraction was measured. The ratio of the extracted H - current and the H - density in the plasma gives an indication of the drift velocity of H - in the plasma. This velocity determines the emittance of the extracted beam. It was found that the H - velocity scales with the square root of the electron temperature. The measured H - densities are compatible with a qualitative model in which dissociative attachment of plasma electrons to vibrationally excited molecules is the most important process. (author). 136 refs.; 39 figs.; 10 tabs

Quantum Monte Carlo for vibrating molecules

International Nuclear Information System (INIS)

Brown, W.R.; Lawrence Berkeley National Lab., CA

1996-08-01

Quantum Monte Carlo (QMC) has successfully computed the total electronic energies of atoms and molecules. The main goal of this work is to use correlation function quantum Monte Carlo (CFQMC) to compute the vibrational state energies of molecules given a potential energy surface (PES). In CFQMC, an ensemble of random walkers simulate the diffusion and branching processes of the imaginary-time time dependent Schroedinger equation in order to evaluate the matrix elements. The program QMCVIB was written to perform multi-state VMC and CFQMC calculations and employed for several calculations of the H 2 O and C 3 vibrational states, using 7 PES's, 3 trial wavefunction forms, two methods of non-linear basis function parameter optimization, and on both serial and parallel computers. In order to construct accurate trial wavefunctions different wavefunctions forms were required for H 2 O and C 3 . In order to construct accurate trial wavefunctions for C 3 , the non-linear parameters were optimized with respect to the sum of the energies of several low-lying vibrational states. In order to stabilize the statistical error estimates for C 3 the Monte Carlo data was collected into blocks. Accurate vibrational state energies were computed using both serial and parallel QMCVIB programs. Comparison of vibrational state energies computed from the three C 3 PES's suggested that a non-linear equilibrium geometry PES is the most accurate and that discrete potential representations may be used to conveniently determine vibrational state energies

Multivariate Analysis of Ladle Vibration

Science.gov (United States)

Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle

2016-08-01

The homogeneity of composition and uniformity of temperature of the steel melt before it is transferred to the tundish are crucial in making high-quality steel product. The homogenization process is performed by stirring the melt using inert gas in ladles. Continuous monitoring of this process is important to make sure the action of stirring is constant throughout the ladle. Currently, the stirring process is monitored by process operators who largely rely on visual and acoustic phenomena from the ladle. However, due to lack of measurable signals, the accuracy and suitability of this manual monitoring are problematic. The actual flow of argon gas to the ladle may not be same as the flow gage reading due to leakage along the gas line components. As a result, the actual degree of stirring may not be correctly known. Various researchers have used one-dimensional vibration, and sound and image signals measured from the ladle to predict the degree of stirring inside. They developed online sensors which are indeed to monitor the online stirring phenomena. In this investigation, triaxial vibration signals have been measured from a cold water model which is a model of an industrial ladle. Three flow rate ranges and varying bath heights were used to collect vibration signals. The Fast Fourier Transform was applied to the dataset before it has been analyzed using principal component analysis (PCA) and partial least squares (PLS). PCA was used to unveil the structure in the experimental data. PLS was mainly applied to predict the stirring from the vibration response. It was found that for each flow rate range considered in this study, the informative signals reside in different frequency ranges. The first latent variables in these frequency ranges explain more than 95 pct of the variation in the stirring process for the entire single layer and the double layer data collected from the cold model. PLS analysis in these identified frequency ranges demonstrated that the latent

The electrochemical reduction processes of solid compounds in high temperature molten salts.

Science.gov (United States)

Xiao, Wei; Wang, Dihua

2014-05-21

Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution-electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

Near-Source Error Sensor Strategies for Active Vibration Isolation of Machines

NARCIS (Netherlands)

Beijers, C.A.J.; Basten, T.G.H.; de Boer, Andries; van den Brink, D.R.; Verheij, J.W.; Sas, P; de Munck, M.

2004-01-01

Due to lightweight construction of vehicles and ships, the reduction of structure borne interior noise problems with passive isolation of engine vibrations might be not sufficient. To improve the isolation, a combination of passive and active isolation techniques can be used (so-called hybrid

Ultra-low-vibration pulse-tube cryocooler system - cooling capacity and vibration

Science.gov (United States)

Ikushima, Yuki; Li, Rui; Tomaru, Takayuki; Sato, Nobuaki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira

2008-09-01

This report describes the development of low-vibration cooling systems with pulse-tube (PT) cryocoolers. Generally, PT cryocoolers have the advantage of lower vibrations in comparison to those of GM cryocoolers. However, cooling systems for the cryogenic laser interferometer observatory (CLIO), which is a gravitational wave detector, require an operational vibration that is sufficiently lower than that of a commercial PT cryocooler. The required specification for the vibration amplitude in cold stages is less than ±1 μm. Therefore, during the development of low-vibration cooling systems for the CLIO, we introduced advanced countermeasures for commercial PT cryocoolers. The cooling performance and the vibration amplitude were evaluated. The results revealed that 4 K and 80 K PT cooling systems with a vibration amplitude of less than ±1 μm and cooling performance of 4.5 K and 70 K at heat loads of 0.5 W and 50 W, respectively, were developed successfully.

Silicon Micromachined Sensor for Broadband Vibration Analysis

Science.gov (United States)

Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

1995-01-01

The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

Adaptation of U(IV) reductant to Savannah River Plant Purex processes

International Nuclear Information System (INIS)

Orebaugh, E.G.

1986-04-01

Partitioning of uranium and plutonium in the Purex process requires the reduction of the extracted Pu(IV) to the less extractable Pu(III). This valence adjustment at SRP has historically been performed by the addition of ferrous ion, which eventually constitutes a major component of high-level waste solids requiring costly permanent disposal. Uranous nitrate, U(IV), is a kinetically fast reductant which may be substituted for Fe(II) without contributing to waste solids. This report documents U(IV) flowsheet development in the miniature mixer-settler equipment at SRL and provides an insight into the mechanisms responsible for the successful direct substitution of U(IV) for Fe(II) in 1B bank extractant. U(IV) will be the reductant of choice when its fast reduction kinetics are required in centrifugal-contactor-based processing. The flowsheets investigated here should transfer to such equipment with minimal modifications

Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

International Nuclear Information System (INIS)

Wang, Yufeng; Zeng, Yongbin; Qu, Ningsong; Zhu, Di

2015-01-01

An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained

A quality control method by ultrasonic vibration energy and diagnosis system at trimming process

International Nuclear Information System (INIS)

Suh, Chang Min; Song, Gil Ho; Pyoun, Young Shik

2007-01-01

In this paper, the characteristics in mechanical properties of ultrasonic cold forging treatment (UCFT) used for the trimming knife and the effects of ultrasonic vibration energy (UVE) into the trimming process on the state of the strip cutting face were studied. And a diagnosis system to quality control for trimming knife and strip cutting face was developed and installed in plant. By the plant application of UCFT, service life of knife was more increased over 100% than that of conventional knife and using the developed diagnosis system, the knife breakage and saw ear have been perfectly detected and quality control of trimming face is effectively obtained

Vibrational spectroscopic study of fluticasone propionate

Science.gov (United States)

Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

2009-03-01

Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

Experimental Study of the Ultrasonic Vibration-Assisted Abrasive Waterjet Micromachining the Quartz Glass

Directory of Open Access Journals (Sweden)

Rongguo Hou

2018-01-01

Full Text Available The ultrasonic vibration is used to enhance the capability of the abrasive water micromachining glass. And, the ultrasonic vibration is activated on the abrasive waterjet nozzle. The quality of the flow is improved, and the velocity of the abrasive is increased because of the addition of the ultrasonic energy. The relevant experimental results indicate that the erosion depth and the material volume removal of the glass are obviously increased when ultrasonic vibration is working. As for the influence of process parameters on the material removal of the glass such as vibration amplitude, system pressure, distance of the standoff, and abrasive size, the experimental results indicate that the system pressure and vibration contribute greatly to the glass material removal. Also, the erosion depth and the volume of material removal are increased with the increase in the vibration amplitude and system pressure. There are some uplifts found at the edge of erosion pit. Then, it can be inferred that the plastic method is an important material removal method during the machining process of ultrasonic vibration-assisted abrasive waterjet.

Free vibration characteristics analysis of rectangular plate with rectangular opening based on Fourier series method

Directory of Open Access Journals (Sweden)

WANG Minhao

2017-08-01

Full Text Available Plate structures with openings are common in many engineering structures. The study of the vibration characteristics of such structures is directly related to the vibration reduction, noise reduction and stability analysis of an overall structure. This paper conducts research into the free vibration characteristics of a thin elastic plate with a rectangular opening parallel to the plate in an arbitrary position. We use the improved Fourier series to represent the displacement tolerance function of the rectangular plate with an opening. We can divide the plate into an eight zone plate to simplify the calculation. We then use linear springs, which are uniformly distributed along the boundary, to simulate the classical boundary conditions and the boundary conditions of the boundaries between the regions. According to the energy functional and variational method, we can obtain the overall energy functional. We can also obtain the generalized eigenvalue matrix equation by studying the extremum of the unknown improved Fourier series expansion coefficients. We can then obtain the natural frequencies and corresponding vibration modes of the rectangular plate with an opening by solving the equation. We then compare the calculated results with the finite element method to verify the accuracy and effectiveness of the method proposed in this paper. Finally, we research the influence of the boundary condition, opening size and opening position on the vibration characteristics of a plate with an opening. This provides a theoretical reference for practical engineering application.

Magnetoelectric coupling of a magnetoelectric flux gate sensor in vibration noise circumstance

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Zhaoqiang Chu

2018-01-01

Full Text Available A magnetoelectric (ME flux gate sensor (MEFGS consisting of piezoelectric PMN-PT single crystals and ferromagnetic amorphous alloy ribbon in a self-differential configuration is featured with the ability of weak magnetic anomaly detection. Here, we further investigated its ME coupling and magnetic field detection performance in vibration noise circumstance, including constant frequency, impact, and random vibration noise. Experimental results show that the ME coupling coefficient of MEFGS is as high as 5700 V/cm*Oe at resonant frequency, which is several orders magnitude higher than previously reported differential ME sensors. It was also found that under constant and impact vibration noise circumstance, the noise reduction and attenuation factor of MEFGS are over 17 and 85.7%, respectively. This work is important for practical application of MEFGS in real environment.

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

Rare earth intermetallic compounds produced by a reduction-diffusion process

International Nuclear Information System (INIS)

Cech, R.E.

1975-01-01

A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

Noncontact measurement of rotating blade vibrations. Doyoku shindo no hisesshoku keisokuho no kenkyu

Energy Technology Data Exchange (ETDEWEB)

Matsuda, Yukio; Endo, Masanori; Sugiyama, Nanahisa; Koshinuma, Takeshi

1989-08-01

The noncontact measurement method of rotating blade vibrations was developed for fans, compressors and turbines, and applied to turbofan engines and industrial gas turbines. The method required no machining of blades and rotor except sensors attached to a casing to detect blade-tips. The method allowed to measure simultaneously the vibration of all blades, by measuring elapsed times of blade-tips rotating from a measuring start point to a detecting point, and detecting the time differences between a vibration and non-vibration condition. The measuring system was composed of the detectors and subsystems for signal processing, control, calculation and display. The vibration wave forms of a few blades and the maximum vibration amplitudes of all the blades were displayed on a realtime basis in an on-line monitoring mode, and an off-line data processing mode was also available for subsequent analyses and reviews. The results of application to existing engines favorably agreed with those of strain gage measurements. 16 refs., 75 figs., 3 tabs.

Phase transition of Ni-Mn-Ga alloy powders prepared by vibration ball milling

International Nuclear Information System (INIS)

Tian, B.; Chen, F.; Tong, Y.X.; Li, L.; Zheng, Y.F.; Liu, Y.; Li, Q.Z.

2011-01-01

Research highlights: → The vibration ball milling with a high milling energy introduces the atomic disorder and large lattice distortion in the alloy during milling and makes the formation of disordered fcc structure phase in the alloy. → The transition temperature and activation energy for disordered fcc → disordered bcc are ∼320 o C and 209 ± 8 kJ/mol, respectively. → The alloy powders annealed at 800 o C for 1 h show a one-stage martensitic transformation with quite lower latent heat compared to the bulk alloy. - Abstract: This study investigated the phase transformation of the flaky shaped Ni-Mn-Ga powder particles with thickness around 1 μm prepared by vibration ball milling and post-annealing. The SEM, XRD, DSC and ac magnetic susceptibility measurement techniques were used to characterize the Ni-Mn-Ga powders. The structural transition of Heusler → disordered fcc occurred in the powders prepared by vibration ball milling (high milling energy) for 4 h, which was different from the structural transition of Heusler → disordered fct of the powders fabricated by planetary ball milling (low milling energy) for 4 h. The two different structures after ball milling should be due to the larger lattice distortion occurred in the vibration ball milling process than in the planetary ball milling process. The structural transition of disordered fcc → disordered bcc took place at ∼320 o C during heating the as-milled Ni-Mn-Ga powders, which was attributed to the elimination of lattice distortion caused by ball milling. The activation energy for this transition was 209 ± 8 kJ/mol. The Ni-Mn-Ga powder annealed at 800 o C mainly contained Heusler austenite phase at room temperature and showed a low volume of martensitic transformation upon cooling. The inhibition of martensitic transformation might be attributed to the reduction of grain size in the annealed Ni-Mn-Ga particles.

Whole-body vibration exercise in postmenopausal osteoporosis

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Magdalena Weber-Rajek

2015-01-01

Full Text Available The report of the World Health Organization (WHO of 2008 defines osteoporosis as a disease characterized by low bone mass and an increased risk of fracture. Postmenopausal osteoporosis is connected to the decrease in estrogens concentration as a result of malfunction of endocrine ovarian function. Low estrogens concentration causes increase in bone demineralization and results in osteoporosis. Physical activity, as a component of therapy of patients with osteoporosis, has been used for a long time now. One of the forms of safe physical activity is the vibration training. Training is to maintain a static position or execution of specific exercises involving the appropriate muscles on a vibrating platform, the mechanical vibrations are transmitted to the body of the patient. According to the piezoelectric theory, pressure induces bone formation in the electrical potential difference, which acts as a stimulant of the process of bone formation. Whole body vibration increases the level of growth hormone and testosterone in serum, preventing sarcopenia and osteoporosis. The aim of this study was to review the literature on vibration exercise in patients with postmenopausal osteoporosis based on the PubMed and Medline database. While searching the database, the following key words were used ‘postmenopausal osteoporosis’ and ‘whole-body vibration exercise’.

Effects of high power ultrasonic vibration on temperature distribution of workpiece in dry creep feed up grinding.

Science.gov (United States)

Paknejad, Masih; Abdullah, Amir; Azarhoushang, Bahman

2017-11-01

Temperature history and distribution of steel workpiece (X20Cr13) was measured by a high tech infrared camera under ultrasonic assisted dry creep feed up grinding. For this purpose, a special experimental setup was designed and fabricated to vibrate only workpiece along two directions by a high power ultrasonic transducer. In this study, ultrasonic effects with respect to grinding parameters including depth of cut (a e ), feed speed (v w ), and cutting speed (v s ) has been investigated. The results indicate that the ultrasonic vibration has considerable effect on reduction of temperature, depth of thermal damage of workpiece and width of temperature contours. Maximum temperature reduction of 25.91% was reported at condition of v s =15m/s, v w =500mm/min, a e =0.4mm in the presence of ultrasonic vibration. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamic Wetting Behavior of Vibrated Droplets on a Micropillared Surface

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Zhi-hai Jia

2016-01-01

Full Text Available The dynamical wetting behavior has been observed under vertical vibration of a water droplet placed on a micropillared surface. The wetting transition takes place under the different processes. In compression process, the droplet is transited from Cassie state to Wenzel state. The droplet undergoes a Wenzel-Cassie wetting transition in restoring process and the droplet bounces off from the surface in bouncing process. Meanwhile, the wetting and dewetting models during vibration are proposed. The wetting transition is confirmed by the model calculation. This study has potential to be used to control the wetting state.

PREFACE: Vibrations at surfaces Vibrations at surfaces

Science.gov (United States)

Rahman, Talat S.

2011-12-01

This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

Role of correlations of lattice vibrations in channeling

International Nuclear Information System (INIS)

Barrett, J.H.; Jackson, D.P.

1980-01-01

Computer simulations of channeling have been done using correlated thermal displacements of the lattice atoms. For the channeling minimum yield and half angles, results are given as a function of temperature. For the surface yield, results are given as a function of angle from the axial direction to supplement earlier results as a function of temperature. In all quantities correlations cause effects qualitatively similar to a reduction in vibration amplitude, although the reduction varies from quantity to quantity. These variations are consistent with the idea that correlations will be most important for a trajectory aligned with the rows and of decreasing importance as the direction of a trajectory approaches a random direction. The largest effect occurs for the surface yield wherein there is a reduction of about 15% for the cases studied so far. (orig.)

Determination of rheological properties of fresh concrete and similar materials in a vibration rheometer

Directory of Open Access Journals (Sweden)

Sandra Juradin

2012-02-01

Full Text Available A vibration rheometer has been developed for the purpose of determining the viscosity coefficient and the yield value of fresh concrete under vibration. The main parts of the apparatus, a test specimen and a vibration source form a unitary oscillatory system whose parameters can be measured with sufficient precision. Two types of fine grained reference material have been prepared and examined; one with a high coefficient of viscosity and the other with a high yield value. The rheological properties of reference materials have been determined in a capillary tube viscometer. Since there is no analytical solution to the flow in the vibration rheometer, the constants of the vibration rheometer have been determined by experiment, for each position of the apparatus piston within the measuring range. The parameters of the flow depend on the maximum acceleration of the vibration source. An increase in acceleration causes an increase in the yield value as well as a reduction in the plastic viscosity coefficient of the material specimen. A testing of fresh mortar has been carried out as well. The obtained results have been compared with the impact on reference materials, which makes the results of our research applicable to fresh vibrated concrete.

An adjoint method of sensitivity analysis for residual vibrations of structures subject to impacts

Science.gov (United States)

Yan, Kun; Cheng, Gengdong

2018-03-01

For structures subject to impact loads, the residual vibration reduction is more and more important as the machines become faster and lighter. An efficient sensitivity analysis of residual vibration with respect to structural or operational parameters is indispensable for using a gradient based optimization algorithm, which reduces the residual vibration in either active or passive way. In this paper, an integrated quadratic performance index is used as the measure of the residual vibration, since it globally measures the residual vibration response and its calculation can be simplified greatly with Lyapunov equation. Several sensitivity analysis approaches for performance index were developed based on the assumption that the initial excitations of residual vibration were given and independent of structural design. Since the resulting excitations by the impact load often depend on structural design, this paper aims to propose a new efficient sensitivity analysis method for residual vibration of structures subject to impacts to consider the dependence. The new method is developed by combining two existing methods and using adjoint variable approach. Three numerical examples are carried out and demonstrate the accuracy of the proposed method. The numerical results show that the dependence of initial excitations on structural design variables may strongly affects the accuracy of sensitivities.

Oxidation-reduction processes in ground water at Naval Weapons Industrial Reserve Plant, Dallas, Texas

Science.gov (United States)

Jones, S.A.; Braun, Christopher L.; Lee, Roger W.

2003-01-01

Concentrations of trichloroethene in ground water at the Naval Weapons Industrial Reserve Plant in Dallas, Texas, indicate three source areas of chlorinated solvents?building 1, building 6, and an off-site source west of the facility. The presence of daughter products of reductive dechlorination of trichloroethene, which were not used at the facility, south and southwest of the source areas are evidence that reductive dechlorination is occurring. In places south of the source areas, dissolved oxygen concentrations indicated that reduction of oxygen could be the dominant process, particularly south of building 6; but elevated dissolved oxygen concentrations south of building 6 might be caused by a leaking water or sewer pipe. The nitrite data indicate that denitrification is occurring in places; however, dissolved hydrogen concentrations indicate that iron reduction is the dominant process south of building 6. The distributions of ferrous iron indicate that iron reduction is occurring in places south-southwest of buildings 6 and 1; dissolved hydrogen concentrations generally support the interpretation that iron reduction is the dominant process in those places. The generally low concentrations of sulfide indicate that sulfate reduction is not a key process in most sampled areas, an interpretation that is supported by dissolved hydrogen concentrations. Ferrous iron and dissolved hydrogen concentrations indicate that ferric iron reduction is the primary oxidation-reduction process. Application of mean first-order decay rates in iron-reducing conditions for trichloroethene, dichloroethene, and vinyl chloride yielded half-lives for those solvents of 231, 347, and 2.67 days, respectively. Decay rates, and thus half-lives, at the facility are expected to be similar to those computed. A weighted scoring method to indicate sites where reductive dechlorination might be likely to occur indicated strong evidence for anaerobic biodegradation of chlorinated solvents at six sites

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.

Mechanisms of Coupled Vibrational Relaxation and Dissociation in Carbon Dioxide.

Science.gov (United States)

Armenise, Iole; Kustova, Elena

2018-05-21

A complete vibrational state-specific kinetic scheme describing dissociating carbon dioxide mixtures is proposed. CO 2 symmetric, bending and asymmetric vibrations and dissociation-recombination are strongly coupled through inter-mode vibrational energy transfers. Comparative study of state-resolved rate coefficients is carried out; the effect of different transitions may vary considerably with temperature. A non-equilibrium 1-D boundary layer flow typical to hypersonic planetary entry is studied in the state-to-state approach. To assess the sensitivity of fluid-dynamic variables and heat transfer to various vibrational transitions and chemical reactions, corresponding processes are successively included to the kinetic scheme. It is shown that vibrational-translational (VT) transitions in the symmetric and asymmetric modes do not alter the flow and can be neglected whereas the VT 2 exchange in the bending mode is the main channel of vibrational relaxation. Inter-mode vibrational exchanges affect the flow implicitly, through energy redistribution enhancing VT relaxation; the dominating role belongs to near-resonant transitions between symmetric and bending modes as well as between CO molecules and CO 2 asymmetric mode. Strong coupling between VT 2 relaxation and chemical reactions is emphasized. While vibrational distributions and average vibrational energy show strong dependence on the kinetic scheme, the heat flux is more sensitive to chemical reactions.

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

Science.gov (United States)

Xu, Long; Lin, Shuyu; Hu, Wenxu

2011-10-01

This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction. Copyright © 2011 Elsevier B.V. All rights reserved.

Design fix for vibration-induced wear in fuel pin bundles

International Nuclear Information System (INIS)

Naas, D.F.; Heck, E.N.

1976-01-01

In summary, results at 45,000 MWd/MTM burnup from the FFTF mixed oxide fuel pin irradiation tests in EBR-II show that reduction of the initial fuel pin bundle clearance and use of 20 percent cold-worked stainless steel ducts virtually eliminate vibration and wear observed in an initial series of 61-pin tests

Effect of electromagnetic vibration on the microstructure of direct chill cast Al-Zn-Mg-Cu alloy

International Nuclear Information System (INIS)

Zuo, Y; Fu, X; Zhu, Q; Li, L; Wang, P; Cui, J

2016-01-01

An electromagnetic vibration was achieved by the combined application of an alternating magnetic field and a stationary magnetic field during direct chill (DC) casting process. The ingots with 200 mm in diameter were prepared under the influence of electromagnetic vibration. The effect of electromagnetic vibration on the microstructure of an Al-Zn-Mg-Cu alloy was studied. The results showed that electromagnetic vibration has a significant effect on the solidification behaviour, under the influence of electromagnetic vibration during DC casting process, the microstructure is significantly refined and the uniformity of microstructure is evidently improved. This paper introduces the DC casting technology with the application of electromagnetic vibration, presents these results and gives corresponding discussions. (paper)

Global vibrations in the wetwell condensation process caused by LOCA in BWR plants

International Nuclear Information System (INIS)

Bjoerndahl, O.; Andersson, Magnus

1998-12-01

basis the GE methodology has been evaluated. The conclusion of this evaluation is that the GE methodology my lead to non-conservative and/or non-unique results when predictions of global vibration loading in secondary systems supported by the building structure. For the CO-case the assumption is made by GE that a conservative loading is established if an acoustic source is applied in the system model at the locations of all the vent pipe exits which is identical in magnitude and in time dependence in all vents. The source is derived from the one pipe experiments. This evaluation shows that the correlation between the time signals of the different vent pipe sources is a very significant parameter. This parameter is not possible to identify from one pipe experiment. The estimates of this parameter will strongly effect the calculated structural response both concerning the magnitude and the spatial characteristics. The assumption made by GE may lead to non-conservative responses in main parts of the building. The method developed by GE to predict responses for the CH-loading is by itself a random process. The responses computed by this method can be shown to be non-unique. The variance of predicted response spectra are significant. This effect is a direct result of the technique used to simulate the random behaviour of the start times of individual chuggs at the location of the vent pipe exits, the so called desyncronisation technique

The Effect of a Vibration Absorber on the Damping Properties of Alpine Skis

Directory of Open Access Journals (Sweden)

Stefan Schwanitz

2018-02-01

Full Text Available Coupled bending-torsion vibrations at the shovel are a severe problem when running an alpine ski at high velocities on hard or icy slopes. Thus, a major goal for ski manufacturers is to dampen vibrations through a proper multi-material design and/or additional absorbers. The aim of this study was to examine the effectiveness of a particular vibration absorber on a commercial slalom ski through a series of laboratory tests as well as a subjective field evaluation. Therefore, two identical pairs of ski were used and the absorber was deactivated on one pair. Laboratory tests revealed reductions of 5% to 49% of bending vibrations on skis with activated absorber. Subjective evaluation by 6 subjects suggested minor differences in the mean of the evaluated criteria turnablity, edge grip, steering behavior and stability towards a better performance of the skis with activated absorber. Subjects were able to identify the absorber mode with a success rate of 61.1%.

Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

International Nuclear Information System (INIS)

Mandal, Aritra; Tokmakoff, Andrei

2015-01-01

We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm −1 . We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions

Investigation into high-frequency-vibration assisted micro-blanking of pure copper foils

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Wang Chunju

2015-01-01

Full Text Available The difficulties encountered during the manufacture of microparts are often associated with size effects relating to material, process and tooling. Utilizing acoustoplastic softening, achieved through a high-frequency vibration assisted micro-blanking process, was introduced to improve the surface finish in micro-blanking. A frequency of 1.0 kHz was chosen to activate the longitudinal vibration mode of the horn tip, using a piezoelectric actuator. A square hole with dimensions of 0.5 mm × 0.5 mm was made, successfully, from a commercial rolled T2 copper foil with 100 μm in thickness. It was found that the maximum blanking force could be reduced by 5% through utilizing the high-frequency vibration. Proportion of the smooth, burnished area in the cut cross-section increases with an increase of the plasticity to fracture, under the high-frequency vibration, which suggests that the vibration introduced is helpful for inhibiting evolution of the crack due to its acoustoplastic softening effect. During blanking, roughness of the burnished surface could be reduced by increasing the vibration amplitude of the punch, which played a role as surface polishing. The results obtained suggest that the high-frequency vibration can be adopted in micro-blanking in order to improve quality of the microparts.

Implementation of internal model based control and individual pitch control to reduce fatigue loads and tower vibrations in wind turbines

Science.gov (United States)

Mohammadi, Ebrahim; Fadaeinedjad, Roohollah; Moschopoulos, Gerry

2018-05-01

Vibration control and fatigue loads reduction are important issues in large-scale wind turbines. Identifying the vibration frequencies and tuning dampers and controllers at these frequencies are major concerns in many control methods. In this paper, an internal model control (IMC) method with an adaptive algorithm is implemented to first identify the vibration frequency of the wind turbine tower and then to cancel the vibration signal. Standard individual pitch control (IPC) is also implemented to compare the performance of the controllers in term of fatigue loads reduction. Finally, the performance of the system when both controllers are implemented together is evaluated. Simulation results demonstrate that using only IMC or IPC alone has advantages and can reduce fatigue loads on specific components. IMC can identify and suppress tower vibrations in both fore-aft and side-to-side directions, whereas, IPC can reduce fatigue loads on blades, shaft and yaw bearings. When both IMC and IPC are implemented together, the advantages of both controllers can be used. The aforementioned analysis and comparisons were not studied in literature and this study fills this gap. FAST, AreoDyn and Simulink are used to simulate the mechanical, aerodynamic and electrical aspects of wind turbine.

DYNAMIC MODELLING OF VIBRATIONS ASSISTED DRILLING

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Mathieu LADONNE

2015-05-01

Full Text Available The number of multi-materials staking configurations for aeronautical structures is increasing, with the evolution of composite and metallic materials. For drilling the fastening holes, the processes of Vibration Assisted Drilling (VAD expand rapidly, as it permits to improve reliability of drilling operations on multilayer structures. Among these processes of VAD, the solution with forced vibrations added to conventional feed to create a discontinuous cutting is the more developed in industry. The back and forth movement allows to improve the evacuation of chips by breaking it. This technology introduces two new operating parameters, the frequency and the amplitude of the oscillation. To optimize the process, the choice of those parameters requires first to model precisely the operation cutting and dynamics. In this paper, a kinematic modelling of the process is firstly proposed. The limits of the model are analysed through comparison between simulations and measurements. The proposed model is used to develop a cutting force model that allows foreseeing the operating conditions which ensure good chips breaking and tool life improvement.

Using periodicity to mitigate ground vibration

DEFF Research Database (Denmark)

Andersen, Lars Vabbersgaard

2015-01-01

Introduction of trenches, barriers and wave impeding blocks on the transmission path between a source and receiver can be used for mitigation of ground vibration. However, to be effective a barrier must have a depth of about one wavelength of the waves to be mitigated. Hence, while great reductions......: A soil with periodic stiffening (ground improvement) and a ground with periodic changes in the surface elevation obtained by artificial landscaping. By means of a two-dimensional finite-element model, the stiffness and mass matrices are determined for a single cell of the ground with horizonal...

Surface quality monitoring for process control by on-line vibration analysis using an adaptive spline wavelet algorithm

Science.gov (United States)

Luo, G. Y.; Osypiw, D.; Irle, M.

2003-05-01

The dynamic behaviour of wood machining processes affects the surface finish quality of machined workpieces. In order to meet the requirements of increased production efficiency and improved product quality, surface quality information is needed for enhanced process control. However, current methods using high price devices or sophisticated designs, may not be suitable for industrial real-time application. This paper presents a novel approach of surface quality evaluation by on-line vibration analysis using an adaptive spline wavelet algorithm, which is based on the excellent time-frequency localization of B-spline wavelets. A series of experiments have been performed to extract the feature, which is the correlation between the relevant frequency band(s) of vibration with the change of the amplitude and the surface quality. The graphs of the experimental results demonstrate that the change of the amplitude in the selective frequency bands with variable resolution (linear and non-linear) reflects the quality of surface finish, and the root sum square of wavelet power spectrum is a good indication of surface quality. Thus, surface quality can be estimated and quantified at an average level in real time. The results can be used to regulate and optimize the machine's feed speed, maintaining a constant spindle motor speed during cutting. This will lead to higher level control and machining rates while keeping dimensional integrity and surface finish within specification.

Phase Evolution During the Carbothermic Reduction Process of Ilmenite Concentrate

Science.gov (United States)

Gou, Hai-Peng; Zhang, Guo-Hua; Chou, Kuo-Chih

2015-02-01

The phase evolution during the carbothermic reduction process of Panzhihua ilmenite concentrate was investigated under argon atmosphere. The Panzhihua ilmenite concentrate briquette with graphite powder was reduced at 1473 K, 1573 K, 1673 K, and 1773 K (1200 °C, 1300 °C, 1400 °C, and 1500 °C) respectively, with the molar ratios of C to FeTiO3 being 4:1 and 5:1. The phase transformation of the briquette reduced at different temperatures was investigated by X-ray diffraction and scanning electron microscope. During the carbothermic reduction process from 1473 K to 1773 K (1200 °C to 1500 °C), it was found that main phases were Fe, Ti3O5, Ti2O3, and TiC x O y . The lowest temperature for the generation of TiC x O y was 1573 K (1300 °C) for both kinds of briquettes with different C contents. The rate controlling step for the carbothermic reduction above 1573 K (1300 °C) obeyed the diffusion model. The reduction degree of the ilmenite was increased by increasing the temperature. With the increase of reaction temperature and reaction time, TiC x O y phase would be reduced to TiC phase.

Isotope separation using vibrationally excited molecules

International Nuclear Information System (INIS)

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

1977-01-01

A system for isotope separation or enrichment wherein molecules of a selected isotope type in a flow of molecules of plural isotope types are vibrationally excited and collided with a background gas to provide enhanced diffusivity for the molecules of the selected isotope type permitting their separate collection. The system typically is for the enrichment of uranium using a uranium hexafluoride gas in combination with a noble gas such as argon. The uranium hexafluoride molecules having a specific isotope of uranium are vibrationally excited by laser radiation. The vibrational energy is converted to a translation energy upon collision with a particle of the background gas and the added translation energy enhances the diffusivity of the selected hexafluoride molecules facilitating its condensation on collection surfaces provided for that purpose. This process is periodically interrupted and the cryogenic flow halted to permit evaporation of the collected molecules to provide a distinct, enriched flow

Supports for shock, vibration and seismic isolation for tube networks

International Nuclear Information System (INIS)

Prisecaru, Ilie; Serban, Viorel; Sandrea Madalina

2005-01-01

The paper presents a solution for diminishing the shocks, vibrations and seismic movements in pipe networks, with a simultaneous reduction in the general stress conditions in piping and supports. Total removal or reduction of vibrations is a hard problem which was not yet tackled either theoretically, in the sense of an analytical procedure for the analysis of occurrence and development of shocks and vibrations in complex systems, or practically, since the current supports and dampers cannot provide enough damping within all the frequency ranges met in the technical domain. Stiffness of classical supports do not allow always satisfactory source isolation to prevent propagation from environment of shocks and vibrations, Considering the actual condition met in the nuclear power plants, power plants and thermal power plants, etc. this paper represents a major practical aid because it provides new solutions for diminishing shocks, vibrations and seismic movements. Aiming at diminishing the effects of vibrations in pipe networks, this paper presents the results obtained in the design, construction and testing of new types of supports that include sandwich type components made up of elastic blade packages with controlled distortion provided by the central and peripheral stiff parts called SERB. With the new type of supports, the control of the distortion at static and dynamic loads and the thermal displacements is achieved by the relative movement among the sandwich structure subassemblies and by the sandwich structure distortion controlled by the central and peripheral distorting parts that generate a non - linear geometric response which has an easily controllable stiffness and damping, due to their non - linear geometric behavior. The supports of the new type are adjustable to the load and distortion level without overstressing the component material, due to a non - linear geometric behavior while the contact pressure among the blades is limited to pre-set values. Due

Integrated active sensor system for real time vibration monitoring.

Science.gov (United States)

Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

2015-11-05

We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0-60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems.

Vibrational spectroscopic study of terbutaline hemisulphate

Science.gov (United States)

Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

2009-05-01

The Raman spectrum of terbutaline hemisulphate is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation; these predictions compare favourably with the observed vibrational spectra. Comparison with previously published infrared data explains several spectral features. The results from this study provide data that can be used for the preparative process monitoring of terbutaline hemisulphate, an important β 2 agonist drug in various dosage forms and its interaction with excipients and other components.

Non-collocated fuzzy logic and input shaping control strategy for elastic joint manipulator: vibration suppression and time response analysis

Energy Technology Data Exchange (ETDEWEB)

Rashidifar, Mohammed Amin [Faculty of Mechanical Engineering, Islamic Azad University, SHADEGAN (Iran, Islamic Republic of); Rashidifar, Ali Amin, E-mail: rashidifar_58@yahoo.com [Computer Science, Islamic Azad University, SHADEGAN (Iran, Islamic Republic of)

2014-07-01

Conventional model-based control strategies are very complex and difficult to synthesize due to high complexity of the dynamics of robots manipulator considering joint elasticity. This paper presents investigations into the development of hybrid control schemes for trajectory tracking and vibration control of a flexible joint manipulator. To study the effectiveness of the controllers, initially a collocated proportional-derivative (P D)-type Fuzzy Logic Controller (FLC) is developed for tip angular position control of a flexible joint manipulator. This is then extended to incorporate a non-collocated Fuzzy Logic Controller and input shaping scheme for vibration reduction of the flexible joint system. The positive zero-vibration-derivative-derivative (ZVDD) shaper is designed based on the properties of the system. Simulation results of the response of the flexible joint manipulator with the controllers are presented in time and frequency domains. The performances of the hybrid control schemes are examined in terms of input tracking capability, level of vibration reduction and time response specifications. Finally, a comparative assessment of the control techniques is presented and discussed. (Author)

Vibration welding system with thin film sensor

Science.gov (United States)

Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

2014-03-18

A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

Electrochemical processing of spent nuclear fuels: An overview of oxide reduction in pyroprocessing technology

Directory of Open Access Journals (Sweden)

Eun-Young Choi

2015-12-01

Full Text Available The electrochemical reduction process has been used to reduce spent oxide fuel to a metallic form using pyroprocessing technology for a closed fuel cycle in combination with a metal-fuel fast reactor. In the electrochemical reduction process, oxides fuels are loaded at the cathode basket in molten Li2O–LiCl salt and electrochemically reduced to the metal form. Various approaches based on thermodynamic calculations and experimental studies have been used to understand the electrode reaction and efficiently treat spent fuels. The factors that affect the speed of the electrochemical reduction have been determined to optimize the process and scale-up the electrolysis cell. In addition, demonstrations of the integrated series of processes (electrorefining and salt distillation with the electrochemical reduction have been conducted to realize the oxide fuel cycle. This overview provides insight into the current status of and issues related to the electrochemical processing of spent nuclear fuels.

Influence of the relative deformation rate on tube processing by ultrasonic vibration drawing

International Nuclear Information System (INIS)

Susan, M.; Bujoreanu, L. G.; Galusca, D. G.; Munteanu, C.; Lliescu, V.

2004-01-01

After a brief review of the friction reversion mechanism during ultrasonic vibration drawing of tubes (UVD), the paper introduces a method to determine the drawing force based on the theorem of total consumed power, in the case of tube processing. The experiments performed on tubes made from 10TiNiCr180 (AISI321) austenitic stainless steel confirm the superiority of UVD technology regarding the diminution of the drawing force, the increase of the plasticity and the improvement of the safety coefficient, tendencies that are enhanced with the decrease of the relative drawing rate. The best results were obtained for the relative drawing rate of 0.12 for which the drawing force decreased with 33%, plasticity increased with 9% and safety coefficient with 22%, as compared to CT. (Author) 10 refs

The dynamic characteristics of harvesting energy from mechanical vibration via piezoelectric conversion

International Nuclear Information System (INIS)

Fan Kang-Qi; Ming Zheng-Feng; Xu Chun-Hui; Chao Feng-Bo

2013-01-01

As an alternative power solution for low-power devices, harvesting energy from the ambient mechanical vibration has received increasing research interest in recent years. In this paper we study the transient dynamic characteristics of a piezoelectric energy harvesting system including a piezoelectric energy harvester, a bridge rectifier, and a storage capacitor. To accomplish this, this energy harvesting system is modeled, and the charging process of the storage capacitor is investigated by employing the in-phase assumption. The results indicate that the charging voltage across the storage capacitor and the gathered power increase gradually as the charging process proceeds, whereas the charging rate slows down over time as the charging voltage approaches to the peak value of the piezoelectric voltage across the piezoelectric materials. In addition, due to the added electrical damping and the change of the system natural frequency when the charging process is initiated, a sudden drop in the vibration amplitude is observed, which in turn affects the charging rate. However, the vibration amplitude begins to increase as the charging process continues, which is caused by the decrease in the electrical damping (i.e., the decrease in the energy removed from the mechanical vibration). This electromechanical coupling characteristic is also revealed by the variation of the vibration amplitude with the charging voltage. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Forming the stress state of a vibroisolated building in the process of mounting rubber steel vibration isolator

Directory of Open Access Journals (Sweden)

Dashevskiy Mikhail Aronovich

2015-12-01

Full Text Available The necessity to specificate the formation process of stress-strain state of buildings in the construction process is a new problem which requires including real production characteristics going beyond calculation models into calculation methods. Today the construction process lacks this specification. When mounting vibroisolators the stress-strein of a structure state is changing. The mounting method of vibroisolators is patented and consists in multistage successive compression loading of each vibroisolator with the constant speed and following fixation of this displacement. The specified engineering method of rubber-steel pads calculation in view of change of their form during deformation, nonlinearity, rheological processes is offered. Resilient pads look like rubber plates rectangular in plane reinforced on the basic surfaces with metal sheets. The influence of a time-variable static load and free vibrations of loaded pads are considered.

Vibration control for precision manufacturing using piezoelectric actuators

Energy Technology Data Exchange (ETDEWEB)

Martinez, D.R.; Hinnerichs, T.D.; Redmond, J.M.

1995-12-31

Piezoelectric actuators provide high frequency, force, and stiffness capabilities along with reasonable Stroke limits, all of which can be used to increase performance levels in precision manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stability diagram is quantified. Experimental results are also given for embedding three piezoelectric actuators in a surrogate photolithography platen to suppress vibrations. These results demonstrate the potential benefit that can be realized by applying advances from the field of adaptive structures to problems in precision manufacturing.

Vibration and acoustic noise emitted by dry-type air-core reactors under PWM voltage excitation

Science.gov (United States)

Li, Jingsong; Wang, Shanming; Hong, Jianfeng; Yang, Zhanlu; Jiang, Shengqian; Xia, Shichong

2018-05-01

According to coupling way between the magnetic field and the structural order, structure mode is discussed by engaging finite element (FE) method and both natural frequency and modal shape for a dry-type air-core reactor (DAR) are obtained in this paper. On the basis of harmonic response analysis, electromagnetic force under PWM (Pulse Width Modulation) voltage excitation is mapped with the structure mesh, the vibration spectrum is gained and the consequences represents that the whole structure vibration predominates in the radial direction, with less axial vibration. Referring to the test standard of reactor noise, the rules of emitted noise of the DAR are measured and analyzed at chosen switching frequency matches the sample resonant frequency and the methods of active vibration and noise reduction are put forward. Finally, the low acoustic noise emission of a prototype DAR is verified by measurement.

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.

Electronic energy transfer through non-adiabatic vibrational-electronic resonance. II. 1D spectra for a dimer

Science.gov (United States)

Tiwari, Vivek; Jonas, David M.

2018-02-01

Vibrational-electronic resonance in photosynthetic pigment-protein complexes invalidates Förster's adiabatic framework for interpreting spectra and energy transfer, thus complicating determination of how the surrounding protein affects pigment properties. This paper considers the combined effects of vibrational-electronic resonance and inhomogeneous variations in the electronic excitation energies of pigments at different sites on absorption, emission, circular dichroism, and hole-burning spectra for a non-degenerate homodimer. The non-degenerate homodimer has identical pigments in different sites that generate differences in electronic energies, with parameters loosely based on bacteriochlorophyll a pigments in the Fenna-Matthews-Olson antenna protein. To explain the intensity borrowing, the excited state vibrational-electronic eigenvectors are discussed in terms of the vibrational basis localized on the individual pigments, as well as the correlated/anti-correlated vibrational basis delocalized over both pigments. Compared to those in the isolated pigment, vibrational satellites for the correlated vibration have the same frequency and precisely a factor of 2 intensity reduction through vibrational delocalization in both absorption and emission. Vibrational satellites for anti-correlated vibrations have their relaxed emission intensity reduced by over a factor 2 through vibrational and excitonic delocalization. In absorption, anti-correlated vibrational satellites borrow excitonic intensity but can be broadened away by the combination of vibronic resonance and site inhomogeneity; in parallel, their vibronically resonant excitonic partners are also broadened away. These considerations are consistent with photosynthetic antenna hole-burning spectra, where sharp vibrational and excitonic satellites are absent. Vibrational-excitonic resonance barely alters the inhomogeneously broadened linear absorption, emission, and circular dichroism spectra from those for a

A Study on the Vibration Measurement and Analysis of Rotating Machine Foundations

Energy Technology Data Exchange (ETDEWEB)

Lee, Jong Rim; Jeon, Kyu Sik; Suh, Young Pyo; Cho, Chul Hwan; Kim, Sung Taeg; Lee, Myung Kyu [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

1996-12-31

To search for the cause of vibration problem of rotating machine in the power plant, first the rotating machine is classified according to their type and each vibration characteristic is reviewed. The criteria for the evaluation of mechanical vibration effect on the structure and human being during the design of machine foundation is described below. The foundation of rotating machine is classified according to its shape and some factors are described which should be considered during dynamic modeling analysis for its correct result. Also the methods of incorporating foundation vibration into mechanical vibration analysis are reviewed. Type of vibration measurement and analysis which is used to find out the dynamic characteristic of structure is described in accordance with its signal processing and measuring method. Measurement of vibration and its analysis when there occurs real vibration troubles in power plant are compared with the results of numerical modeling as case studies. (author). 16 refs., 23 figs.

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

Conditions for Stable Chip Breaking and Provision of Machined Surface Quality While Turning with Asymmetric Tool Vibrations

OpenAIRE

Шелег, В. К.; Молочко, В. И.; Данильчик, С. С.

2015-01-01

The paper considers a process of turning structural steel with asymmetric tool vibrations directed along feeding. Asymmetric vibrations characterized by asymmetry coefficient of vibration cycle, their frequency and amplitude are additionally transferred to the tool in the turning process with the purpose to crush chips. Conditions of stable chip breaking and obtaining optimum dimensions of chip elements have been determined in the paper. In order to reduce a negative impact of the vibration a...

Single step preparation of NdFeB alloy by magnesiothermic reduction-diffusion process

International Nuclear Information System (INIS)

Singha, Vinay Kant; Surendranathana, A.O.; John Berchmans, L.

2014-01-01

Magnesiothermic reduction is a new approach to produce the NdFeB alloy on a commercial scale. Similar studies were conducted for the preparation of LaNi 5 and SmCo 5 using magnesium as the reductant. In the present investigation NdFeB Hard magnetic bulk materials were synthesized by metallothermic 'Reduction – Diffusion (R-D) Process' using Magnesium as a reductant. For this process oxide precursors of Nd, Fe and B were blended with flux (LiCl/CaCl 2 ) and Mg chips were sandwiched in alternate layers. Thermal analysis (TGA/DTA) was carried out to find the dissociation and decomposition temperature of the reactants. The phase analysis, structure, and elemental composition were assessed by X-ray diffraction (XRD) and electron dispersive spectrometry (EDS). The infrared (IR) spectra were recorded by Fourier transform infrared spectrometer (FTIR). The morphological features and particle size was assessed by scanning electron microscope (SEM). The magnetic behaviour of the alloy was assessed using electron paramagnetic resonance (EPR) and vibratory sample magnetometer (VSM). From these studies it has been concluded that the NdFeB magnetic particles can be prepared using magnesium as the reductant. The process is faster and consumes very less amount of energy for the completion as compared to conventional calciothermic reduction process. Traces of MgO were detected in the alloy which increases the perpendicular anisotropy, thus increasing the coercivity of the material

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...

NPP planning based on analysis of ground vibration caused by collapse of large-scale cooling towers

Energy Technology Data Exchange (ETDEWEB)

Lin, Feng; Ji, Hongkui [Department of Structural Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092 (China); Gu, Xianglin, E-mail: gxl@tongji.edu.cn [Department of Structural Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092 (China); Li, Yi [Department of Structural Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092 (China); Wang, Mingreng; Lin, Tao [East China Electric Power Design Institute Co., Ltd, No. 409 Wuning Road, Shanghai 200063 (China)

2015-12-15

Highlights: • New recommendations for NPP planning were addressed taking into account collapse-induced ground vibration. • Critical factors influencing the collapse-induced ground vibration were investigated. • Comprehensive approach was presented to describe the initiation and propagation of collapse-induced disaster. - Abstract: Ground vibration induced by collapse of large-scale cooling towers can detrimentally influence the safe operation of adjacent nuclear-related facilities. To prevent and mitigate these hazards, new planning methods for nuclear power plants (NPPs) were studied considering the influence of these hazards. First, a “cooling tower-soil” model was developed, verified, and used as a numerical means to investigate ground vibration. Afterwards, five critical factors influencing collapse-induced ground vibration were analyzed in-depth. These influencing factors included the height and weight of the towers, accidental loads, soil properties, overlying soil, and isolation trench. Finally, recommendations relating to the control and mitigation of collapse-induced ground vibration in NPP planning were proposed, which addressed five issues, i.e., appropriate spacing between a cooling tower and the nuclear island, control of collapse modes, sitting of a cooling tower and the nuclear island, application of vibration reduction techniques, and the influence of tower collapse on surroundings.

Vibrations and Eigenvalues

Indian Academy of Sciences (India)

We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

Lessons Learned on the Application of Vibration Absorbers for Enhanced Cannon Stabilization

Directory of Open Access Journals (Sweden)

Eric Kathe

2001-01-01

Full Text Available This paper will summarize the successful application of muzzle-end vibration absorbers to reduce cannon vibration. This technology constitutes a weapons stabilization approach that focuses on passive mechanical structural modification of the cannon, rather than relying upon an external control law to actively cancel vibrations. Challenges encountered during field testing, non-ideal behavior, and performance evaluation using digital signal processing will be highlighted.

General principles of control method of passenger car bodies bending vibration parameters

Science.gov (United States)

Skachkov, A. N.; Samoshkin, S. L.; Korshunov, S. D.; Kobishchanov, V. V.; Antipin, D. Ya

2018-03-01

Weight reduction of passenger cars is a promising direction of reducing the cost of their production and increasing transportation profitability. One way to reduce the weight of passenger cars is the lightweight metal body design by means of using of high-strength aluminum alloys, low-alloy and stainless steels. However, it has been found that the limit of the lightweight metal body design is not determined by the total mode of deformation, but its flexural rigidity, as the latter influences natural frequencies of body bending vibrations. With the introduction of mandatory certification for compliance with the Customs Union technical regulations, the following index was confirmed: “first natural frequency of body bending vibrations in the vertical plane”. This is due to the fact that vibration, noise and car motion depend on this index. To define the required indexes, the principles of the control method of bending vibration parameters of passenger car bodies are proposed in this paper. This method covers all stages of car design – development of design documentation, manufacturing and testing experimental and pilot models, launching the production. The authors also developed evaluation criteria and the procedure of using the results for introduction of control method of bending vibration parameters of passenger car bodies.

Gene regulation and noise reduction by coupling of stochastic processes

Science.gov (United States)

Ramos, Alexandre F.; Hornos, José Eduardo M.; Reinitz, John

2015-02-01

Here we characterize the low-noise regime of a stochastic model for a negative self-regulating binary gene. The model has two stochastic variables, the protein number and the state of the gene. Each state of the gene behaves as a protein source governed by a Poisson process. The coupling between the two gene states depends on protein number. This fact has a very important implication: There exist protein production regimes characterized by sub-Poissonian noise because of negative covariance between the two stochastic variables of the model. Hence the protein numbers obey a probability distribution that has a peak that is sharper than those of the two coupled Poisson processes that are combined to produce it. Biochemically, the noise reduction in protein number occurs when the switching of the genetic state is more rapid than protein synthesis or degradation. We consider the chemical reaction rates necessary for Poisson and sub-Poisson processes in prokaryotes and eucaryotes. Our results suggest that the coupling of multiple stochastic processes in a negative covariance regime might be a widespread mechanism for noise reduction.

Gene regulation and noise reduction by coupling of stochastic processes.

Science.gov (United States)

Ramos, Alexandre F; Hornos, José Eduardo M; Reinitz, John

2015-02-01

Here we characterize the low-noise regime of a stochastic model for a negative self-regulating binary gene. The model has two stochastic variables, the protein number and the state of the gene. Each state of the gene behaves as a protein source governed by a Poisson process. The coupling between the two gene states depends on protein number. This fact has a very important implication: There exist protein production regimes characterized by sub-Poissonian noise because of negative covariance between the two stochastic variables of the model. Hence the protein numbers obey a probability distribution that has a peak that is sharper than those of the two coupled Poisson processes that are combined to produce it. Biochemically, the noise reduction in protein number occurs when the switching of the genetic state is more rapid than protein synthesis or degradation. We consider the chemical reaction rates necessary for Poisson and sub-Poisson processes in prokaryotes and eucaryotes. Our results suggest that the coupling of multiple stochastic processes in a negative covariance regime might be a widespread mechanism for noise reduction.

Vibration-Assisted Handling of Dry Fine Powders

Directory of Open Access Journals (Sweden)

Paul Dunst

2018-04-01

Full Text Available Since fine powders tend strongly to adhesion and agglomeration, their processing with conventional methods is difficult or impossible. Typically, in order to enable the handling of fine powders, chemicals are added to increase the flowability and reduce adhesion. This contribution shows that instead of additives also vibrations can be used to increase the flowability, to reduce adhesion and cohesion, and thus to enable or improve processes such as precision dosing, mixing, and transport of very fine powders. The methods for manipulating powder properties are described in detail and prototypes for experimental studies are presented. It is shown that the handling of fine powders can be improved by using low-frequency, high-frequency or a combination of low- and high-frequency vibration.

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

Engineering Vibrationally Assisted Energy Transfer in a Trapped-Ion Quantum Simulator

Science.gov (United States)

Gorman, Dylan J.; Hemmerling, Boerge; Megidish, Eli; Moeller, Soenke A.; Schindler, Philipp; Sarovar, Mohan; Haeffner, Hartmut

2018-01-01

Many important chemical and biochemical processes in the condensed phase are notoriously difficult to simulate numerically. Often, this difficulty arises from the complexity of simulating dynamics resulting from coupling to structured, mesoscopic baths, for which no separation of time scales exists and statistical treatments fail. A prime example of such a process is vibrationally assisted charge or energy transfer. A quantum simulator, capable of implementing a realistic model of the system of interest, could provide insight into these processes in regimes where numerical treatments fail. We take a first step towards modeling such transfer processes using an ion-trap quantum simulator. By implementing a minimal model, we observe vibrationally assisted energy transport between the electronic states of a donor and an acceptor ion augmented by coupling the donor ion to its vibration. We tune our simulator into several parameter regimes and, in particular, investigate the transfer dynamics in the nonperturbative regime often found in biochemical situations.

Vibration mode and vibration shape under excitation of a three phase model transformer core

Science.gov (United States)

Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi

2018-04-01

Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.

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

Prediction of vibration level in tunnel blasting; Tonneru kusshin happa ni yotte reiki sareru shindo no reberu yosoku ho

Energy Technology Data Exchange (ETDEWEB)

Hirata, A. [Kumamoto Industries Univ, Kumamoto (Japan); Yamamoto, M. [Asahi Chemical Industry Co. Ltd., Tokyo (Japan); Inaba, C. [Nishimatsu Construction Co. Ltd., Kanagawa (Japan); Kaneko, K. [Hokkaido Univ (Japan)

1997-08-01

For avoiding the generation of public hazard due to ground vibration causes by blasting in tunneling, it is important to devise a blasting method for ensuring the level of the ground vibration caused thereby under a limit, and an exact predication of ground vibration before blasting is desirable. In this study, the characteristics of the ground vibration caused by tunnel blasting are analyzed, and a summary of amplitude spectra calculating method is described. A theoretical analysis method for predicting the vibration level is proposed based on spectrum-multiplicative method. Vibration caused by multistage blasting in tunneling is most strong and deemed as important. When observing the process of elastic wave motion caused by multistage blasting being measured, the process can be divided into three element processes in frequency area as vibration source spectrum, transmission attenuation spectrum and frequency response function vibrating test, and, with the multiplication of them, the amplitude spectra at an observation portion can be estimated. 12 refs., 12 figs.

analysis of profitability and poverty reduction of yoghurt processing

African Journals Online (AJOL)

Admin

KEY WORDS: Profitability, poverty reduction, yoghurt, processing, employment ... 70% percent of the rural working population (Joshua,. 1999). With about 76 out of every 120 people living ... traditionally the difference between total revenue and ... (70%) of the respondents were males while 30% were females. The age ...

Force illusions and drifts observed during muscle vibration.

Science.gov (United States)

Reschechtko, Sasha; Cuadra, Cristian; Latash, Mark L

2018-01-01

We explored predictions of a scheme that views position and force perception as a result of measuring proprioceptive signals within a reference frame set by ongoing efferent process. In particular, this hypothesis predicts force illusions caused by muscle vibration and mediated via changes in both afferent and efferent components of kinesthesia. Healthy subjects performed accurate steady force production tasks by pressing with the four fingers of one hand (the task hand) on individual force sensors with and without visual feedback. At various times during the trials, subjects matched the perceived force using the other hand. High-frequency vibration was applied to one or both of the forearms (over the hand and finger extensors). Without visual feedback, subjects showed a drop in the task hand force, which was significantly smaller under the vibration of that forearm. Force production by the matching hand was consistently higher than that of the task hand. Vibrating one of the forearms affected the matching hand in a manner consistent with the perception of higher magnitude of force produced by the vibrated hand. The findings were consistent between the dominant and nondominant hands. The effects of vibration on both force drift and force mismatching suggest that vibration led to shifts in both signals from proprioceptors and the efferent component of perception, the referent coordinate and/or coactivation command. The observations fit the hypothesis on combined perception of kinematic-kinetic variables with little specificity of different groups of peripheral receptors that all contribute to perception of forces and coordinates. NEW & NOTEWORTHY We show that vibration of hand/finger extensors produces consistent errors in finger force perception. Without visual feedback, finger force drifted to lower values without a drift in the matching force produced by the other hand; hand extensor vibration led to smaller finger force drift. The findings fit the scheme with

Nonlinear Model of Vibrating Screen to Determine Permissible Spring Deterioration for Proper Separation

Directory of Open Access Journals (Sweden)

Cristian G. Rodriguez

2016-01-01

Full Text Available Springs of vibrating screens are prone to fatigue induced failure because they operate in a heavy duty environment, with abrasive dust and under heavy cyclic loads. If a spring breaks, the stiffness at supporting positions changes, and therefore the amplitude of motion and the static and dynamic angular inclination of deck motion also change. This change in the amplitude and in the inclination of motion produces a reduction in separation efficiency. Available models are useful to determine motion under nominal operating conditions when angular displacement is not significant. However in practice there is significant angular motion during startup, during shutdown, or under off-design operating conditions. In this article, a two-dimensional three-degree-of-freedom nonlinear model that considers significant angular motion and damping is developed. The proposed model allows the prediction of vibrating screen behavior when there is a reduction in spring stiffness. Making use of this model for an actual vibrating screen in operation in industry has permitted determining a limit for spring’s failure before separation efficiency is affected. This information is of practical value for operation and maintenance staff helping to determine whether or not it is necessary to change springs, and hence optimizing stoppage time.

Ship Vibrations

DEFF Research Database (Denmark)

Sørensen, Herman

1997-01-01

Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board......Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board...

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].

Vibration control for precision manufacturing at Sandia National Laboratories

International Nuclear Information System (INIS)

Hinnerichs, T.; Martinez, D.

1995-01-01

Sandia National Laboratories performs R and D in structural dynamics and vibration suppression for precision applications in weapon systems, space, underwater, transportation and civil structures. Over the last decade these efforts have expanded into the areas of active vibration control and ''smart'' structures and material systems. In addition, Sandia has focused major resources towards technology to support weapon product development and agile manufacturing capability for defense and industrial applications. This paper will briefly describe the structural dynamics modeling and verification process currently in place at Sandia that supports vibration control and some specific applications of these techniques to manufacturing in the areas of lithography, machine tools and flexible robotics

Vibration control for precision manufacturing at Sandia National Laboratories

Energy Technology Data Exchange (ETDEWEB)

Hinnerichs, T.; Martinez, D. [Sandia National Labs., Albuquerque, NM (United States). Structural Dynamics and Vibration Control Dept.

1995-04-01

Sandia National Laboratories performs R and D in structural dynamics and vibration suppression for precision applications in weapon systems, space, underwater, transportation and civil structures. Over the last decade these efforts have expanded into the areas of active vibration control and ``smart`` structures and material systems. In addition, Sandia has focused major resources towards technology to support weapon product development and agile manufacturing capability for defense and industrial applications. This paper will briefly describe the structural dynamics modeling and verification process currently in place at Sandia that supports vibration control and some specific applications of these techniques to manufacturing in the areas of lithography, machine tools and flexible robotics.

Determination of temperature and pressure in the calcium reduction process

International Nuclear Information System (INIS)

Arceri, Mariana E.

1997-01-01

The calcium reduction process consists in the reduction of uranium tetrafluoride (UF 4 ) with calcium in a refractory material crucible, in order to obtain metallic uranium. The crucible is in turn contained in a steel reactor, heated by means of an induction coil to bring the reagents from the environmental temperature to the temperature necessary for the reaction starting. For the design of the reactor, mathematical expressions that allow to estimate the temperature and pressure of the system have been developed

Application for vibration monitoring of aspheric surface machining based on wireless sensor networks

Science.gov (United States)

Han, Chun Guang; Guo, Yin Biao; Jiang, Chen

2010-05-01

Any kinds of tiny vibration of machine tool parts will have a great influence on surface quality of the workpiece at ultra-precise machining process of aspheric surface. At present the major way for decreasing influence of vibration is machining compensation technology. Therefore it is important for machining compensation control to acquire and transmit these vibration signals effectively. This paper presents a vibration monitoring system of aspheric surface machining machine tool based on wireless sensor networks (WSN). Some key issues of wireless sensor networks for vibration monitoring system of aspheric surface machining are discussed. The reliability of data transmission, network communication protocol and synchronization mechanism of wireless sensor networks are studied for the vibration monitoring system. The proposed system achieves multi-sensors vibration monitoring involving the grinding wheel, the workpiece and the workbench spindle. The wireless transmission of vibration signals is achieved by the combination with vibration sensor nodes and wireless network. In this paper, these vibration sensor nodes are developed. An experimental platform is structured which employs wireless sensor networks to the vibration monitoring system in order to test acquisition and wireless transmission of vibration signal. The test results show that the proposed system can achieve vibration data transmission effectively and reliability and meet the monitoring requirements of aspheric surface machining machine tool.

Vibrational relaxation and energy transfer of matrix isolated HCl and DCl

Energy Technology Data Exchange (ETDEWEB)

Wiesenfeld, J.M.

1977-12-01

Vibrational kinetic and spectroscopic studies have been performed on matrix-isolated HCl and DCl between 9 and 20 K. Vibrational relaxation rates for v = 2 and v = 1 were measured by a tunable infrared laser-induced, time-resolved fluorescence technique. In an Ar matrix, vibrational decay times are faster than radiative and it is found that HCl relaxes about 35 times more rapidly than CCl, in spite of the fact that HCl must transfer more energy to the lattice than DCl. This result is explained by postulating that the rate-determining step for vibrational relaxation produces a highly rotationally excited guest in a V yield R step; rotational relaxation into lattice phonons follows rapidly. HCl v = 1, but not v = 2, excitation rapidly diffuses through the sample by a resonant dipole-dipole vibrational energy transfer process. Molecular complexes, and in particular the HCl dimer, relax too rapidly for direct observation, less than or approximately 1 ..mu..s, and act as energy sinks in the energy diffusion process. The temperature dependence for all these processes is weak--less than a factor of two between 9 and 20 K. Vibrational relaxation of HCl in N/sub 2/ and O/sub 2/ matrices is unobservable, presumably due to rapid V yield V transfer to the host. A V yield R binary collision model for relaxation in solids is successful in explaining the HCl(DCl)/Ar results as well as results of other experimenters. The model considers relaxation to be the result of ''collisions'' due to molecular motion in quantized lattice normal modes--gas phase potential parameters can fit the matrix kinetic data.

Vibrational relaxation and energy transfer of matrix isolated HCl and DCl

International Nuclear Information System (INIS)

Wiesenfeld, J.M.

1977-12-01

Vibrational kinetic and spectroscopic studies have been performed on matrix-isolated HCl and DCl between 9 and 20 K. Vibrational relaxation rates for v = 2 and v = 1 were measured by a tunable infrared laser-induced, time-resolved fluorescence technique. In an Ar matrix, vibrational decay times are faster than radiative and it is found that HCl relaxes about 35 times more rapidly than CCl, in spite of the fact that HCl must transfer more energy to the lattice than DCl. This result is explained by postulating that the rate-determining step for vibrational relaxation produces a highly rotationally excited guest in a V yield R step; rotational relaxation into lattice phonons follows rapidly. HCl v = 1, but not v = 2, excitation rapidly diffuses through the sample by a resonant dipole-dipole vibrational energy transfer process. Molecular complexes, and in particular the HCl dimer, relax too rapidly for direct observation, less than or approximately 1 μs, and act as energy sinks in the energy diffusion process. The temperature dependence for all these processes is weak--less than a factor of two between 9 and 20 K. Vibrational relaxation of HCl in N 2 and O 2 matrices is unobservable, presumably due to rapid V yield V transfer to the host. A V yield R binary collision model for relaxation in solids is successful in explaining the HCl(DCl)/Ar results as well as results of other experimenters. The model considers relaxation to be the result of ''collisions'' due to molecular motion in quantized lattice normal modes--gas phase potential parameters can fit the matrix kinetic data

Off-axis Modal Active Vibration Control Of Rotational Vibrations

NARCIS (Netherlands)

Babakhani, B.; de Vries, Theodorus J.A.; van Amerongen, J.

Collocated active vibration control is an effective and robustly stable way of adding damping to the performance limiting vibrations of a plant. Besides the physical parameters of the Active Damping Unit (ADU) containing the collocated actuator and sensor, its location with respect to the

Fluoroscopic dose reduction by acquisition frame rate reduction and image processing

International Nuclear Information System (INIS)

Fritz, S.L.; Mirvis, S.E.; Pals, S.O.

1986-01-01

A new design for fluoroscopic exposure reduction incorporates pulsed x-ray exposure, progressive scan video acquisition at frame rates below 30 Hz, interlaced video display at 30 Hz, and a video rate image processing. To evaluate this design, a variety of phantom systems have been developed to measure the impact of low frame rate pulsed digital fluoroscopy on the performance of several clinical tasks (e.g., catheter placement). The authors are currently using these phantoms with a digital fluoroscopy system using continuous x-ray, interlaced video acquisition and variable acquisition frame rate. The design of their target digital fluoroscopic system, sample image sequences, and the results of some preliminary phantom studies are reported

MEMS-based thick film PZT vibrational energy harvester

DEFF Research Database (Denmark)

Lei, Anders; Xu, Ruichao; Thyssen, Anders

2011-01-01

We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using a mechan......We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using...... a mechanical front side protection of an SOI wafer with screen printed PZT thick film. The fabricated harvester device produces 14.0 μW with an optimal resistive load of 100 kΩ from 1g (g=9.81 m s-2) input acceleration at its resonant frequency of 235 Hz....

Vibration in car repair work.

Science.gov (United States)

Hansson, J E; Eklund, L; Kihlberg, S; Ostergren, C E

1987-03-01

The main objective of the study was to find efficient hand tools which caused only minor vibration loading. Vibration measurements were carried out under standardised working conditions. The time during which car body repairers in seven companies were exposed to vibration was determined. Chisel hammers, impact wrenches, sanders and saws were the types of tools which generated the highest vibration accelerations. The average daily exposure at the different garages ranged from 22 to 70 min. The risk of vibration injury is currently rated as high. The difference between the highest and lowest levels of vibration was considerable in most tool categories. Therefore the choice of tool has a major impact on the magnitude of vibration exposure. The importance of choosing the right tools and working methods is discussed and a counselling service on vibration is proposed.

Preparation of spherical particles by vibrating orifice technique

Science.gov (United States)

Shibata, Shuichi; Tomizawa, Atsushi; Yoshikawa, Hidemi; Yano, Tetsuji; Yamane, Masayuki

2000-05-01

Preparation of micrometer-sized spherical particles containing Rhodamine 6G (R6G) has been investigated for the spherical cavity micro-laser. Using phenyl triethoxy silane (PTES) as a starting material, R6G-doped monodisperse spherical particles were prepared by the vibrating orifice technique. Processing consists of two major processes: (1) Hydrolysis and polymerization of PTES and (2) Droplet formation from PTES oligomers by vibrating orifice technique. A cylindrical liquid jet passing through the orifice of 10 and 20 micrometers in diameter breaks up into equal- sized droplets by mechanical vibration. Alcohol solvent of these droplets was evaporated during flying with carrier gas and subsequently solidified in ammonium water trap. For making smooth surface and god shaped particles, control of molecular weight of PTES oligomer was essential. R6G-doped hybrid spherical particles of 4 to 10 micrometers size of cavity structure were successfully obtained. The spherical particles were pumped by a second harmonic pulse of Q- switched Nd:YAG laser and laser emission peaks were observed at wavelengths which correspond to the resonance modes.

Vibration insensitive interferometry

Science.gov (United States)

Millerd, James; Brock, Neal; Hayes, John; Kimbrough, Brad; North-Morris, Michael; Wyant, James C.

2017-11-01

The largest limitation of phase-shifting interferometry for optical testing is the sensitivity to the environment, both vibration and air turbulence. An interferometer using temporal phase-shifting is very sensitive to vibration because the various phase shifted frames of interferometric data are taken at different times and vibration causes the phase shifts between the data frames to be different from what is desired. Vibration effects can be reduced by taking all the phase shifted frames simultaneously and turbulence effects can be reduced by averaging many measurements. There are several techniques for simultaneously obtaining several phase-shifted interferograms and this paper will discuss two such techniques: 1) Simultaneous phase-shifting interferometry on a single detector array (PhaseCam) and 2) Micropolarizer phase-shifting array. The application of these techniques for the testing of large optical components, measurement of vibrational modes, the phasing of segmented optical components, and the measurement of deformations of large diffuse structures is described.

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.

Development of an innovative device for ultrasonic elliptical vibration cutting.

Science.gov (United States)

Zhou, Ming; Hu, Linhua

2015-07-01

An innovative ultrasonic elliptical vibration cutting (UEVC) device with 1st resonant mode of longitudinal vibration and 3rd resonant mode of bending vibration was proposed in this paper, which can deliver higher output power compared to previous UEVC devices. Using finite element method (FEM), resonance frequencies of the longitudinal and bending vibrations were tuned to be as close as possible in order to excite these two vibrations using two-phase driving voltages at a single frequency, while wave nodes of the longitudinal and bending vibrations were also adjusted to be as coincident as possible for mounting the device at a single fixed point. Based on the simulation analysis results a prototype device was fabricated, then its vibration characteristics were evaluated by an impedance analyzer and a laser displacement sensor. With two-phase sinusoidal driving voltages both of 480 V(p-p) at an ultrasonic frequency of 20.1 kHz, the developed prototype device achieved an elliptical vibration with a longitudinal amplitude of 8.9 μm and a bending amplitude of 11.3 μm. The performance of the developed UEVC device is assessed by the cutting tests of hardened steel using single crystal diamond tools. Experimental results indicate that compared to ordinary cutting process, the tool wear is reduced significantly by using the proposed device. Copyright © 2015 Elsevier B.V. All rights reserved.

Nanoscale reduction of graphene oxide thin films and its characterization.

Science.gov (United States)

Lorenzoni, M; Giugni, A; Di Fabrizio, E; Pérez-Murano, Francesc; Mescola, A; Torre, B

2015-07-17

In this paper, we report on a method to reduce thin films of graphene oxide (GO) to a spatial resolution better than 100 nm over several tens of micrometers by means of an electrochemical scanning probe based lithography. In situ tip-current measurements show that an edged drop in electrical resistance characterizes the reduced areas, and that the reduction process is, to a good approximation, proportional to the applied bias between the onset voltage and the saturation thresholds. An atomic force microscope (AFM) quantifies the drop of the surface height for the reduced profile due to the loss of oxygen. Complementarily, lateral force microscopy reveals a homogeneous friction coefficient of the reduced regions that is remarkably lower than that of native graphene oxide, confirming a chemical change in the patterned region. Micro Raman spectroscopy, which provides access to insights into the chemical process, allows one to quantify the restoration and de-oxidation of the graphitic network driven by the electrochemical reduction and to determine characteristic length scales. It also confirms the homogeneity of the process over wide areas. The results shown were obtained from accurate analysis of the shift, intensity and width of Raman peaks for the main vibrational bands of GO and reduced graphene oxide (rGO) mapped over large areas. Concerning multilayered GO thin films obtained by drop-casting we have demonstrated an unprecedented lateral resolution in ambient conditions as well as an improved control, characterization and understanding of the reduction process occurring in GO randomly folded multilayers, useful for large-scale processing of graphene-based material.

Improving the effectiveness of detailed processing by dynamic control of processing with high sports range

Directory of Open Access Journals (Sweden)

Yu.V. Shapoval

2017-12-01

Full Text Available In this article the possibility of increasing the efficiency of the processing of parts with a diameter of up to 20 mm is analyzed, namely: vibration resistance of the cutting process at pinching due to cutting speed control in the processing, forecasting and selection of rotational frequencies, which ensure the stability of the processing system, controlling the dynamics of the process of displacement of the additional mass. The method of investigation of vibration processes during the sharpening is developed. As a result of the processing of experimental data, it was found that when an oscillatory motion is applied to the spindle rotation, the overall level of oscillation decreases, which is reflected on the quality of the treated surface. The choice of a previously known spindle rotation frequency range at which the lowest value of the oscillation amplitude of the instrument is observed in the radial direction to the detail part, allows you to increase the processing efficiency while maintaining the drawing requirements for roughness by increasing the spindle rotational speed. The combination of the node of the own forms of oscillation and the cutting zone, by dynamically controlling the fluctuations of the lathe armature due to the increase of the inertia characteristics of the machine and the reduction of the oscillation amplitude of the tool, can improve the accuracy of machining and roughness of the processed surface of the component at higher spindle speeds.

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

Directory of Open Access Journals (Sweden)

Jackson W. Cryns

2013-01-01

Full Text Available Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random, and sine on random (SOR input vibration scenarios; the implications of source vibration characteristics on harvester design are discussed. The rise in popularity of harvesting energy from ambient vibrations has made compact, energy dense piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. Variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. The results agree with numerical and theoretical predictions in the previous literature for optimal power harvesting in sinusoidal and flat broadband vibration scenarios. Going beyond idealized steady-state sinusoidal and flat random vibration input, experimental SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibration sources significantly alter power generation and processing requirements by varying harvested power, shifting optimal conditioning impedance, inducing voltage fluctuations, and ultimately rendering idealized sinusoidal and random analyses incorrect.

Simulation of multivariate stationary stochastic processes using dimension-reduction representation methods

Science.gov (United States)

Liu, Zhangjun; Liu, Zenghui; Peng, Yongbo

2018-03-01

In view of the Fourier-Stieltjes integral formula of multivariate stationary stochastic processes, a unified formulation accommodating spectral representation method (SRM) and proper orthogonal decomposition (POD) is deduced. By introducing random functions as constraints correlating the orthogonal random variables involved in the unified formulation, the dimension-reduction spectral representation method (DR-SRM) and the dimension-reduction proper orthogonal decomposition (DR-POD) are addressed. The proposed schemes are capable of representing the multivariate stationary stochastic process with a few elementary random variables, bypassing the challenges of high-dimensional random variables inherent in the conventional Monte Carlo methods. In order to accelerate the numerical simulation, the technique of Fast Fourier Transform (FFT) is integrated with the proposed schemes. For illustrative purposes, the simulation of horizontal wind velocity field along the deck of a large-span bridge is proceeded using the proposed methods containing 2 and 3 elementary random variables. Numerical simulation reveals the usefulness of the dimension-reduction representation methods.

Application of vibration to wrist and hand skin affects fingertip tactile sensation

Science.gov (United States)

Lakshminarayanan, Kishor; Lauer, Abigail W; Ramakrishnan, Viswanathan; Webster, John G; Seo, Na Jin

2015-01-01

A recent study showed that fingertip pads’ tactile sensation can improve by applying imperceptible white-noise vibration to the skin at the wrist or dorsum of the hand in stroke patients. This study further examined this behavior by investigating the effect of both imperceptible and perceptible white-noise vibration applied to different locations within the distal upper extremity on the fingertip pads’ tactile sensation in healthy adults. In 12 healthy adults, white-noise vibration was applied to one of four locations (dorsum hand by the second knuckle, thenar and hypothenar areas, and volar wrist) at one of four intensities (zero, 60%, 80%, and 120% of the sensory threshold for each vibration location), while the fingertip sensation, the smallest vibratory signal that could be perceived on the thumb and index fingertip pads, was assessed. Vibration intensities significantly affected the fingertip sensation (P sensation (P sensation (P sensation (P > 0.01), all compared with the zero vibration condition. This effect with vibration intensity conforms to the stochastic resonance behavior. Nonspecificity to the vibration location suggests the white-noise vibration affects higher level neuronal processing for fingertip sensing. Further studies are needed to elucidate the neural pathways for distal upper extremity vibration to impact fingertip pad tactile sensation. PMID:26177959

Vibration Analysis of a Residential Building

Directory of Open Access Journals (Sweden)

Sampaio Regina Augusta

2015-01-01

Full Text Available The aim of this paper is to present the results of a study regarding vibration problems in a 17 storey residential building during pile driving in its vicinity. The structural design of the building was checked according to the Brazilian standards NBR6118 and NBR6123, and using commercial finite element software. An experimental analysis was also carried out using low frequency piezo-accelerometers attached to the building structure. Structure vibrations were recorded under ambient conditions. Four monitoring tests were performed on different days. The objective of the first monitoring test was an experimental modal analysis. To obtain de modal parameters, data was processed in the commercial software ARTEMIS employing two methods: the Stochastic Subspace Identification and the Frequency Domain Decomposition. Human comfort was investigated considering the International Standard ISO 2631. The Portuguese standard, NP2074, was also used as a reference, since it aims to limit the adverse effects of vibrations in structures caused by pile driving in the vicinity of the structure. The carried out experimental tests have shown that, according to ISO2301, the measure vibration levels are above the acceptance limits. However, velocity peaks are below the limits established by NP2074. It was concluded that, although the structure has adequate capacity to resist internal forces according to normative criteria, it has low horizontal stiffness, which could be verified by observing the vibration frequencies and mode shapes obtained with the finite element models, and its similarity with the experimental results. Thus, the analyses indicate the occurrence of discomfort by the residents.

Sensitivity of molecular vibrational dynamics to energy exchange rate constants

International Nuclear Information System (INIS)

Billing, G D; Coletti, C; Kurnosov, A K; Napartovich, A P

2003-01-01

The sensitivity of molecular vibrational population dynamics, governing the CO laser operated in fundamental and overtone transitions, to vibration-to-vibration rate constants is investigated. With this aim, three rate constant sets have been used, differing in their completeness (i.e. accounting for single-quantum exchange only, or for multi-quantum exchange with a limited number of rate constants obtained by semiclassical calculations, and, finally, with an exhaustive set of rate constants including asymmetric exchange processes, as well) and in the employed interaction potential. The most complete set among these three is introduced in this paper. An existing earlier kinetic model was updated to include the latter new data. Comparison of data produced by kinetic modelling with the above mentioned sets of rate constants shows that the vibrational distribution function, and, in particular, the CO overtone laser characteristics, are very sensitive to the choice of the model. The most complete model predicts slower evolution of the vibrational distribution, in qualitative agreement with experiments

Vibration condition monitoring of planetary gearbox under varying external load

Energy Technology Data Exchange (ETDEWEB)

Bartelmus, W.; Zimroz, R. [Wroclaw University of Technology, Wroclaw (Poland)

2009-01-15

The paper shows that for condition monitoring of planetary gearboxes it is important to identify the external varying load condition. In the paper, systematic consideration has been taken of the influence of many factors on the vibration signals generated by a system in which a planetary gearbox is included. These considerations give the basis for vibration signal interpretation, development of the means of condition monitoring, and for the scenario of the degradation of the planetary gearbox. Real measured vibration signals obtained in the industrial environment are processed. The signals are recorded during normal operation of the diagnosed objects, namely planetary gearboxes, which are a part of the driving system used in a bucket wheel excavator, used in lignite mines. It has been found that the most important factor of the proper planetary gearbox condition is connected with perturbation of arm rotation, where an arm rotation gives rise to a specific vibration signal whose properties are depicted by a short-time Fourier transform (STFT) and Wigner-Ville distribution presented as a time-frequency map. The paper gives evidence that there are two dominant low-frequency causes that influence vibration signal modulation, i.e. the varying load, which comes from the nature of the bucket wheel digging process, and the arm/carrier rotation. These two causes determine the condition of the planetary gearboxes considered.

An experimental and analytical investigation into the effects of process vibrations on material removal rates during polishing

Science.gov (United States)

Mullany, B.; Mainuddin, M.; Williams, W.; Keanini, R.

2013-06-01

Experimental testing, using both commercially available polishing machines and a specially built test platform, demonstrates that material removal rates (MRRs) observed during polishing of fused silica are strongly affected by nanometer-scale vibration amplitudes. Specifically, a nanometer level increase in system vibrations can produce MRRs approximately 150% higher than on an inherently smoother running machine. Moreover the higher spatial frequency surface roughness values are little-effected by the spectral content of the polishing machine. Polishing under controlled conditions, using the test platform, shows that for vibration amplitudes, A ≲ 1.6 μm, and over a fairly wide range of vibration frequencies, MRR increases almost linearly with increasing input power. By contrast, for A ≳ 10 μm, MRR exhibits a rapid decay with increasing A. Order of magnitude analyses and physical arguments are presented in order to explain the qualitatively distinct MRR trends observed. In the small-amplitude limit, A ≲ 1.6 μm, two arguments are presented which suggest that the total observed removal rate, MRRtot, reflects the superposed action of chemical-mechanical removal, MRRcm, and vibration-driven, flow-induced removal, MRRflow, i.e., MRRtot=MRRcm+MRRflow. The analyses further indicate that MRRflow primarily reflects cyclic viscous shears and pressure gradients extant within the thin, non-Newtonian slurry film that exists between the polishing tool and workpiece. Shears and pressure gradients, and corresponding flow-induced MRRs, are, in turn, found to scale as √A /do ω, where A is the vibration amplitude, do is the characteristic gap thickness between the tool and workpiece, and ω is the vibration frequency. In the large-amplitude limit, A ≳ 5 μm, experimental measurements and a simple scaling argument show that the polishing slurry film becomes thick enough that the workpiece and polishing tool lose direct contact. In this limit, observed MRRs thus reflect

Collisional flow of vibrational energy into surrounding vibrational fields within S1 benzene

International Nuclear Information System (INIS)

Tang, K.Y.; Parmenter, C.S.

1983-01-01

Vapor phase fluorescence spectra are used to determine the absolute rate constants for the collisional transfer of vibrational energy from initial single vibronic levels of S 1 benzene into the surrounding S 1 vibronic field. 11 initial levels are probed with vibrational energies ranging to 2368 cm -1 where the level density is about 10 per cm -1 . CO, isopentane, and S 0 benzene are the collision partners. Benzene rate constants are three to four times gas kinetic for all levels, and electronic energy switching between the initial S 1 molecule and the S 0 collision partner probably makes important contributions. Isopentane efficiencies range from one to two times gas kinetic. Most of the transfer from low S 1 levels occurs with excitation of vibrational energy within isopentane. These V--V contributions decline to only about 10% for the high transfer. CO-induced transfer is by V-T,R processes for all levels. The CO efficiency rises from about 0.1 for low regions to about unity for levels above 1500 cm -1 . The CO efficiencies retain significant sensitivity to initial level identity even in the higher regions. Propensity rules derived from collisional mode-to-mode transfer among lower levels of S 1 benzene are used to calculate the relative CO efficiencies. The calculated efficiencies agree well enough with the data to suggest that it may be meaningful to model vibrational equilibration with the use of propensity rules. The rules suggest that only a small number of levels among the thousands surrounding a high initial level contribute significantly to the total relaxation cross section and that this number is rather independent of the level density

Detection of surface cracking in steel pipes based on vibration data using a multi-class support vector machine classifier

Science.gov (United States)

Mustapha, S.; Braytee, A.; Ye, L.

2017-04-01

In this study, we focused at the development and verification of a robust framework for surface crack detection in steel pipes using measured vibration responses; with the presence of multiple progressive damage occurring in different locations within the structure. Feature selection, dimensionality reduction, and multi-class support vector machine were established for this purpose. Nine damage cases, at different locations, orientations and length, were introduced into the pipe structure. The pipe was impacted 300 times using an impact hammer, after each damage case, the vibration data were collected using 3 PZT wafers which were installed on the outer surface of the pipe. At first, damage sensitive features were extracted using the frequency response function approach followed by recursive feature elimination for dimensionality reduction. Then, a multi-class support vector machine learning algorithm was employed to train the data and generate a statistical model. Once the model is established, decision values and distances from the hyper-plane were generated for the new collected data using the trained model. This process was repeated on the data collected from each sensor. Overall, using a single sensor for training and testing led to a very high accuracy reaching 98% in the assessment of the 9 damage cases used in this study.

Electron energy distribution functions and thermalization times in methane and in argon--methane mixtures: An effect of vibrational excitation processes

International Nuclear Information System (INIS)

Krajcar-Bronic, I.; Kimura, M.

1995-01-01

Electron thermalization in methane and argon--methane mixtures is studied by using the Boltzmann equation. The presence of low-lying vibrational excited states in methane significantly changes electron energy distribution functions and relaxation times. We found that (i) the mean electron energy just below the first vibrational excited state is reached faster by 1000 times when the vibrational states are taken into account, and (ii) electron energy distribution functions have distinct peaks at energy intervals equal to the vibrational threshold energies. Both these effects are due to large vibrational stopping cross section. The thermalization time in mixtures of argon--methane (without vibrational states) smoothly changes as the mixture composition varies, and no significant difference in the electron energy distribution function is observed. When the vibrational excited states are taken into account, thermalization is almost completely defined by CH 4 , even at very low fractional concentrations of CH 4 . The sensitivity of the electron energy distribution functions on the momentum transfer cross sections used in calculation on the thermalization is discussed. copyright 1995 American Institute of Physics

[Hand-arm vibration syndrome in caisson miners].

Science.gov (United States)

Kákosy, T; Németh, L; Hazay, B; Posgay, M; Diner, J

1997-07-06

Authors examined 43 caisson-miners with symptoms of the upper extremities because of suspicion of hand-arm vibration syndrome. Also vibration measurements were performed on the pneumatic hammer used by the workers. The acceleration of the vibration exceeded 2.5-3.5 times the maximum allowable level according to the ISO 5349. Symptoms and signs of hand-arm vibration syndrome were found in 39 cases (90.7%). The vascular, peripheral neurological and locomotor system of the upper extremities were affected in similar frequency: 54.8; 51.6 and 51.2%, respectively. The most common angiological alteration was the Raynaud's phenomenon. Neurologically predominated the tunnel syndromes. Among the osteoarticular lesions the degenerative phenomena were the most frequent. In most cases more than one pathological alteration occurred. Fatigue fracture of the spinous process of vertebra D. I. appeared in one single case, degenerative changes of cervical spine in 34 patients (79.1%). The very common occurrence of the locomotor alterations and tunnel syndromes respectively can be explained probably also by the high physical stress required by this profession. The detailed examination of the locomotor system is very important by the periodical screening of the caisson-miners.

Uncertainty Quantification for Monitoring of Civil Structures from Vibration Measurements

Science.gov (United States)

Döhler, Michael; Mevel, Laurent

2014-05-01

Health Monitoring of civil structures can be performed by detecting changes in the modal parameters of a structure, or more directly in the measured vibration signals. For a continuous monitoring the excitation of a structure is usually ambient, thus unknown and assumed to be noise. Hence, all estimates from the vibration measurements are realizations of random variables with inherent uncertainty due to (unknown) process and measurement noise and finite data length. In this talk, a strategy for quantifying the uncertainties of modal parameter estimates from a subspace-based system identification approach is presented and the importance of uncertainty quantification in monitoring approaches is shown. Furthermore, a damage detection method is presented, which is based on the direct comparison of the measured vibration signals without estimating modal parameters, while taking the statistical uncertainty in the signals correctly into account. The usefulness of both strategies is illustrated on data from a progressive damage action on a prestressed concrete bridge. References E. Carden and P. Fanning. Vibration based condition monitoring: a review. Structural Health Monitoring, 3(4):355-377, 2004. M. Döhler and L. Mevel. Efficient multi-order uncertainty computation for stochastic subspace identification. Mechanical Systems and Signal Processing, 38(2):346-366, 2013. M. Döhler, L. Mevel, and F. Hille. Subspace-based damage detection under changes in the ambient excitation statistics. Mechanical Systems and Signal Processing, 45(1):207-224, 2014.

Vibration Energy Harvesting Potential for Turbomachinery Applications

Directory of Open Access Journals (Sweden)

Adrian STOICESCU

2018-03-01

Full Text Available The vibration energy harvesting process represents one of the research directions for increasing power efficiency of electric systems, increasing instrumentation nodes autonomy in hard to reach locations and decreasing total system mass by eliminating cables and higher-power adapters. Research based on the possibility of converting vibration energy into useful electric energy is used to evaluate the potential of its use on turbomachinery applications. Aspects such as the structure and characteristics of piezoelectric generators, harvesting networks, their setup and optimization, are considered. Finally, performance test results are shown using piezoelectric systems on a turbine engine.

The role of electron-impact vibrational excitation in electron transport through gaseous tetrahydrofuran

Energy Technology Data Exchange (ETDEWEB)

Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Do, T. P. T. [School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

2015-03-28

In this paper, we report newly derived integral cross sections (ICSs) for electron impact vibrational excitation of tetrahydrofuran (THF) at intermediate impact energies. These cross sections extend the currently available data from 20 to 50 eV. Further, they indicate that the previously recommended THF ICS set [Garland et al., Phys. Rev. A 88, 062712 (2013)] underestimated the strength of the electron-impact vibrational excitation processes. Thus, that recommended vibrational cross section set is revised to address those deficiencies. Electron swarm transport properties were calculated with the amended vibrational cross section set, to quantify the role of electron-driven vibrational excitation in describing the macroscopic swarm phenomena. Here, significant differences of up to 17% in the transport coefficients were observed between the calculations performed using the original and revised cross section sets for vibrational excitation.

Catalytic/non-catalytic combination process for nitrogen oxides reduction

International Nuclear Information System (INIS)

Luftglass, B.K.; Sun, W.H.; Hofmann, J.E.

1992-01-01

This patent describes a process for the reduction of nitrogen oxides in the effluent from the combustion of a carbonaceous fuel. It comprises introducing a nitrogenous treatment agent comprising urea, one or more of the hydrolysis products of urea, ammonia, compounds which produce ammonia as a by-product, ammonium salts of organic acids, 5- or 6-membered heterocyclic hydrocarbons having at least one cyclic nitrogen, hydroxy amino hydrocarbons, or mixtures thereof into the effluent at an effluent temperature between about 1200 degrees F and about 2100 degrees F; and contacting the treated effluent under conditions effective to reduce the nitrogen oxides in the effluent with a catalyst effective for the reduction of nitrogen oxides in the presence of ammonia

Nonlinear Response of Vibrational Conveyers with Nonideal Vibration Exciter: Superharmonic and Subharmonic Resonance

Directory of Open Access Journals (Sweden)

H. Bayıroğlu

2012-01-01

Full Text Available Vibrational conveyers with a centrifugal vibration exciter transmit their load based on the jumping method. Common unbalanced-mass driver oscillates the trough. The motion is strictly related to the vibrational parameters. The transition over resonance of a vibratory system, excited by rotating unbalances, is important in terms of the maximum vibrational amplitude produced and the power demand on the drive for the crossover. The mechanical system is driven by the DC motor. In this study, the working ranges of oscillating shaking conveyers with nonideal vibration exciter have been analyzed analytically for superharmonic and subharmonic resonances by the method of multiple scales and numerically. The analytical results obtained in this study agree well with the numerical results.

Single-molecule electronics: Cooling individual vibrational modes by the tunneling current.

Science.gov (United States)

Lykkebo, Jacob; Romano, Giuseppe; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

2016-03-21

Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes can, in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions, or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular "heat sink" where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the "cooling mode," given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.

Model-based failure detection for cylindrical shells from noisy vibration measurements.

Science.gov (United States)

Candy, J V; Fisher, K A; Guidry, B L; Chambers, D H

2014-12-01

Model-based processing is a theoretically sound methodology to address difficult objectives in complex physical problems involving multi-channel sensor measurement systems. It involves the incorporation of analytical models of both physical phenomenology (complex vibrating structures, noisy operating environment, etc.) and the measurement processes (sensor networks and including noise) into the processor to extract the desired information. In this paper, a model-based methodology is developed to accomplish the task of online failure monitoring of a vibrating cylindrical shell externally excited by controlled excitations. A model-based processor is formulated to monitor system performance and detect potential failure conditions. The objective of this paper is to develop a real-time, model-based monitoring scheme for online diagnostics in a representative structural vibrational system based on controlled experimental data.

Vibration suppression in cutting tools using collocated piezoelectric sensors/actuators with an adaptive control algorithm

Energy Technology Data Exchange (ETDEWEB)

Radecki, Peter P [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory; Bement, Matthew T [Los Alamos National Laboratory

2008-01-01

The machining process is very important in many engineering applications. In high precision machining, surface finish is strongly correlated with vibrations and the dynamic interactions between the part and the cutting tool. Parameters affecting these vibrations and dynamic interactions, such as spindle speed, cut depth, feed rate, and the part's material properties can vary in real-time, resulting in unexpected or undesirable effects on the surface finish of the machining product. The focus of this research is the development of an improved machining process through the use of active vibration damping. The tool holder employs a high bandwidth piezoelectric actuator with an adaptive positive position feedback control algorithm for vibration and chatter suppression. In addition, instead of using external sensors, the proposed approach investigates the use of a collocated piezoelectric sensor for measuring the dynamic responses from machining processes. The performance of this method is evaluated by comparing the surface finishes obtained with active vibration control versus baseline uncontrolled cuts. Considerable improvement in surface finish (up to 50%) was observed for applications in modern day machining.

Recovery of Work-Related Stress: Complaint Reduction and Work-Resumption are Relatively Independent Processes

NARCIS (Netherlands)

Vente, W. de; Kamphuis, J.H.; Blonk, R.W.; Emmelkamp, P.M.

2015-01-01

Purpose The process of recovery from work-related stress, consisting of complaint reduction and work-resumption, is not yet fully understood. The aim of this study was to investigate predictors of complaint reduction and work-resumption, as well as testing complaint reduction as a mediator in the

Recovery of work-related stress: Complaint reduction and work-resumption are relatively independent processes

NARCIS (Netherlands)

de Vente, W.; Kamphuis, J.H.; Blonk, R.W.B.; Emmelkamp, P.M.G.

2015-01-01

Purpose: The process of recovery from work-related stress, consisting of complaint reduction and work-resumption, is not yet fully understood. The aim of this study was to investigate predictors of complaint reduction and work-resumption, as well as testing complaint reduction as a mediator in the

Study on the Effect of Reciprocating Pump Pipeline System Vibration on Oil Transportation Stations

Directory of Open Access Journals (Sweden)

Hongfang Lu

2018-01-01

Full Text Available Due to the periodic movement of the piston in the reciprocating pump, the fluid will cause a pressure pulsation, and the resulting pipeline vibration may lead to instrument distortion, pipe failure and equipment damage. Therefore, it is necessary to study the vibration phenomena of reciprocating pump pipelines based on pressure pulsation theory. This paper starts from the reciprocating pump pipe pressure pulsation caused by a fluid, pressure pulsation in the pipeline and the unbalanced exciting force is calculated under the action of the reciprocating pump. Then, the numerical simulation model is established based on the pipe beam model, and the rationality of the numerical simulation method is verified by indoor experiments. Finally, a case study is taken as an example to analyze the vibration law of the pipeline system, and vibration reduction measures are proposed. The following main conclusions are drawn from the analysis: (1 unbalanced exciting forces are produced in the elbows or tee joints, and it can also influence the straight pipe to different levels; (2 in actual engineering, it should be possible to prevent the simultaneous settlement of multiple places; (3 the vibration amplitude increases with the pipe thermal stress, and when the oil temperature is higher than 85 °C, it had a greater influence on the vertical vibration amplitude of the pipe.

Preliminary reduction of chromium ore using Si sludge generated in silicon wafer manufacturing process

Directory of Open Access Journals (Sweden)

Jung W.-G.

2018-01-01

Full Text Available In order to promote the recycling of by-product from Si wafer manufacturing process and to develop environment-friend and low cost process for ferrochrome alloy production, a basic study was performed on the preliminary reduction reaction between chromium ore and the Si sludge, comprised of SiC and Si particles, which is recovered from the Si wafer manufacturing process for the semiconductor and solar cell industries. Pellets were first made by mixing chromium ore, Si sludge, and some binders in the designed mixing ratios and were then treated at different temperatures in the 1116°C–1388°C range in an ambient atmosphere. Cordierite and SiO2 were confirmed to be formed in the products after the reduction. Additionally, metal particles were observed in the product with Fe, Cr, and Si components. It is found that temperatures above 1300°C are necessary for the reduction of the chromium ore by the Si sludge. The reduction ratio for Fe was evaluated quantitatively for our experimental conditions, and the proper mixing ratio was suggested for the pre-reduction of the chromium ore by the Si sludge. This study provides basic information for the production of ferrochrome alloys on the pre-reduction of chromium ore using Si sludge.

Preparation of rare earth-cobalt magnet alloy by reduction-diffusion process

International Nuclear Information System (INIS)

Krishnan, T.S.

1980-01-01

Preparation of rare earth-cobalt alloys by reduction-diffusion (R-D) process is described. The process essentially involves mixing of the rare earth oxide and cobalt/cobalt oxide powders in proper proportion and high temperature reduction of the charge in hydrogen atmosphere, followed by aqueous leaching of the reduced mass to yield the alloy powder. Comparison is made of the magnetic properties of the R-D powder with those of the powder prepared by the direct melting (DM) route and it is observed from the reported values for SmCo 5 that the energy product of the R-D powder (approximately 22 MGOe) is only marginally lower than that of the directly melted alloy (approximately 25 MGOe). The paper also includes the results of studies carried out at the Bhabha Atomic Research Centre, Bombay, on the preparation of misch metal-cobalt alloy by the R-D process. (auth.)

Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

Science.gov (United States)

Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

2006-04-20

Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

Quality improvement of organic thin films deposited on vibrating substrates

Energy Technology Data Exchange (ETDEWEB)

Paredes, Y.A.; Caldas, P.G.; Prioli, R.; Cremona, M., E-mail: cremona@fis.puc-rio.br

2011-12-30

Most of the Organic Light-Emitting Diodes (OLEDs) have a multilayered structure composed of functional organic layers sandwiched between two electrodes. Thin films of small molecules are generally deposited by thermal evaporation onto glass or other rigid or flexible substrates. The interface state between two organic layers in OLED device depends on the surface morphology of the layers and affects deeply the OLED performance. The morphology of organic thin films depends mostly on substrate temperature and deposition rate. Generally, the control of the substrate temperature allows improving the quality of the deposited films. For organic compounds substrate temperature cannot be increased too much due to their poor thermal stability. However, studies in inorganic thin films indicate that it is possible to modify the morphology of a film by using substrate vibration without increasing the substrate temperature. In this work, the effect of the resonance vibration of glass and silicon substrates during thermal deposition in high vacuum environment of tris(8-quinolinolate)aluminum(III) (Alq{sub 3}) and N,N Prime -Bis(naphthalene-2-yl)-N,N Prime -bis(phenyl)-benzidine ({beta}-NPB) organic thin films with different deposition rates was investigated. The vibration used was in the range of hundreds of Hz and the substrates were kept at room temperature during the process. The nucleation and subsequent growth of the organic films on the substrates have been studied by atomic force microscopy technique. For Alq{sub 3} and {beta}-NPB films grown with 0.1 nm/s as deposition rate and using a frequency of 100 Hz with oscillation amplitude of some micrometers, the results indicate a reduction of cluster density and a roughness decreasing. Moreover, OLEDs fabricated with organic films deposited under these conditions improved their power efficiency, driven at 4 mA/cm{sup 2}, passing from 0.11 lm/W to 0.24 lm/W with an increase in their luminance of about 352 cd/m{sup 2

Study on Nonlinear Vibration Analysis of Gear System with Random Parameters

Science.gov (United States)

Tong, Cao; Liu, Xiaoyuan; Fan, Li

2018-03-01

In order to study the dynamic characteristics of gear nonlinear vibration system and the influence of random parameters, firstly, a nonlinear stochastic vibration analysis model of gear 3-DOF is established based on Newton’s Law. And the random response of gear vibration is simulated by stepwise integration method. Secondly, the influence of stochastic parameters such as meshing damping, tooth side gap and excitation frequency on the dynamic response of gear nonlinear system is analyzed by using the stability analysis method such as bifurcation diagram and Lyapunov exponent method. The analysis shows that the stochastic process can not be neglected, which can cause the random bifurcation and chaos of the system response. This study will provide important reference value for vibration engineering designers.

Theoretical resonant electron-impact vibrational excitation, dissociative recombination and dissociative excitation cross sections of ro-vibrationally excited BeH"+ ion

International Nuclear Information System (INIS)

Laporta, V.; Chakrabarti, K.; Celiberto, R.; Janev, R. K.; Mezei, J. Zs.; Niyonzima, S.; Tennyson, J.; Schneider, I.F.

2017-01-01

A theoretical study of resonant vibrational excitation, dissociative recombination and dissociative excitation processes of the beryllium monohydride cation, BeH"+ , induced by electron impact, is reported. Full sets of ro-vibrationally-resolved cross sections and of the corresponding Maxwellian rate coefficients are presented for the three processes. Particular emphasis is given to the high-energy behaviour. Potential curves of "2σ"+, "2σ and "2δ symmetries and the corresponding resonance widths, obtained from R-matrix calculations, provide the input for calculations which use a local complex-potential model for resonant collisions in each of the three symmetries. Rotational motion of nuclei and isotopic effects are also discussed. The relevant results are compared with those obtained using a multichannel quantum defect theory method. Full results are available from the Phys4Entry database.

Time-resolved vibrational spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Tokmakoff, Andrei [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Champion, Paul [Northeastern Univ., Boston, MA (United States); Heilweil, Edwin J. [National Inst. of Standards and Technology (NIST), Boulder, CO (United States); Nelson, Keith A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ziegler, Larry [Boston Univ., MA (United States)

2009-05-14

This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE's Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all fiveof DOE's grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

Agglomeration of powders with a new-coupled vibration-compaction device

Directory of Open Access Journals (Sweden)

Serris Eric

2017-01-01

Full Text Available Inorganic powder recycling should be a crucial process for the “smart factories” in the future. A complex three-phase system (bauxite mixed with ordinary Portland cement and water with a new-coupled vibration-compaction device is studied. The compressive stress of compacts seems to be improved by using this device at low compaction pressure leaving the other characteristics unchanged. The tomographic study of macroscopic porosities shows differences in the pores repartitions inside vibrated and untreated compacts. Classic porosity repartition is shown in the classic compacted bauxite compacts whereas in the vibrated-compacted bauxite exhibits inhomogeneities. Despite this, we find these results quite promising for further investigations.

Stochastic output error vibration-based damage detection and assessment in structures under earthquake excitation

Science.gov (United States)

Sakellariou, J. S.; Fassois, S. D.

2006-11-01

A stochastic output error (OE) vibration-based methodology for damage detection and assessment (localization and quantification) in structures under earthquake excitation is introduced. The methodology is intended for assessing the state of a structure following potential damage occurrence by exploiting vibration signal measurements produced by low-level earthquake excitations. It is based upon (a) stochastic OE model identification, (b) statistical hypothesis testing procedures for damage detection, and (c) a geometric method (GM) for damage assessment. The methodology's advantages include the effective use of the non-stationary and limited duration earthquake excitation, the handling of stochastic uncertainties, the tackling of the damage localization and quantification subproblems, the use of "small" size, simple and partial (in both the spatial and frequency bandwidth senses) identified OE-type models, and the use of a minimal number of measured vibration signals. Its feasibility and effectiveness are assessed via Monte Carlo experiments employing a simple simulation model of a 6 storey building. It is demonstrated that damage levels of 5% and 20% reduction in a storey's stiffness characteristics may be properly detected and assessed using noise-corrupted vibration signals.

Portable vibration exciter

Science.gov (United States)

Beecher, L. C.; Williams, F. T.

1970-01-01

Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

Neck muscle vibration can improve sensorimotor function in patients with neck pain.

Science.gov (United States)

Beinert, Konstantin; Keller, Martin; Taube, Wolfgang

2015-03-01

People with neck pain display a diminished joint position sense and disturbed postural control, which is thought to be a result of impaired somatosensory afferent activity and/or integration. Afferent processing can be artificially manipulated by vibration and was shown to reduce motor performance in healthy subjects. However, the effect of vibration on sensorimotor function in neck pain patients is scarcely investigated. To assess the effect of neck muscle vibration on joint position sense and postural control in neck pain subjects and healthy controls. Case control study. Thirteen neck pain patients and 10 healthy controls participated in the present study. Cervical joint position sense and dynamic and static postural stability. Short-term, targeted neck muscle vibration with 100 Hz was applied after baseline measurement. Vibration had opposite effects in patients and healthy subjects. Patients showed improved joint position sense (pneck pain. Thus, vibration may be used to counteract sensorimotor impairment of the cervical spine. Potential underlying mechanisms are discussed. Copyright © 2015. Published by Elsevier Inc.

Ochratoxin A reduction in meat sausages using processing methods practiced in households.

Science.gov (United States)

Pleadin, Jelka; Perši, Nina; Kovačević, Dragan; Vulić, Ana; Frece, Jadranka; Markov, Ksenija

2014-01-01

The aim of this study was to investigate the possibilities of ochratoxin A (OTA) reduction in home-made meat products. Meat sausages (n = 50) produced from raw materials coming from pigs exposed to OTA-contaminated feed, were subject to common heat processes practiced in households (cooking, frying and baking). Concentrations of OTA in pre- and post-processed products were quantified using a validated immunoassay method, enzyme-linked immunosorbent assay, and confirmed using a high-performance liquid chromatography with fluorescence detection. In line with the differences in recipes used and the degree of OTA accumulation in raw materials, OTA concentrations established in Mediterranean and roast sausages were lower than those found in liver and blood sausages. Baking of contaminated sausages at the temperatures of 190-220°C (for 60 min) resulted in significant reduction of OTA levels (75.8%), while 30-min cooking (at 100°C) and frying (at 170°C) proved to be significantly less effective (e.g. yielding OTA reductions of 7.4% and 12.6%, respectively). The results pointed out that despite high OTA stability, heat processes are capable of reducing its concentration in home-made meat products, depending on the processing modality used.

Automated pre-processing and multivariate vibrational spectra analysis software for rapid results in clinical settings

Science.gov (United States)

Bhattacharjee, T.; Kumar, P.; Fillipe, L.

2018-02-01

Vibrational spectroscopy, especially FTIR and Raman, has shown enormous potential in disease diagnosis, especially in cancers. Their potential for detecting varied pathological conditions are regularly reported. However, to prove their applicability in clinics, large multi-center multi-national studies need to be undertaken; and these will result in enormous amount of data. A parallel effort to develop analytical methods, including user-friendly software that can quickly pre-process data and subject them to required multivariate analysis is warranted in order to obtain results in real time. This study reports a MATLAB based script that can automatically import data, preprocess spectra— interpolation, derivatives, normalization, and then carry out Principal Component Analysis (PCA) followed by Linear Discriminant Analysis (LDA) of the first 10 PCs; all with a single click. The software has been verified on data obtained from cell lines, animal models, and in vivo patient datasets, and gives results comparable to Minitab 16 software. The software can be used to import variety of file extensions, asc, .txt., .xls, and many others. Options to ignore noisy data, plot all possible graphs with PCA factors 1 to 5, and save loading factors, confusion matrices and other parameters are also present. The software can provide results for a dataset of 300 spectra within 0.01 s. We believe that the software will be vital not only in clinical trials using vibrational spectroscopic data, but also to obtain rapid results when these tools get translated into clinics.

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

Recovery Of Nickel From Spent Nickel-Cadmium Batteries Using A Direct Reduction Process

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Shin D.J.

2015-06-01

Full Text Available Most nickel is produced as Ferro-Nickel through a smelting process from Ni-bearing ore. However, these days, there have been some problems in nickel production due to exhaustion and the low-grade of Ni-bearing ore. Moreover, the smelting process results in a large amount of wastewater, slag and environmental risk. Therefore, in this research, spent Ni-Cd batteries were used as a base material instead of Ni-bearing ore for the recovery of Fe-Ni alloy through a direct reduction process. Spent Ni-Cd batteries contain 24wt% Ni, 18.5wt% Cd, 12.1% C and 27.5wt% polymers such as KOH. For pre-treatment, Cd was vaporized at 1024K. In order to evaluate the reduction conditions of nickel oxide and iron oxide, pre-treated spent Ni-Cd batteries were experimented on under various temperatures, gas-atmospheres and crucible materials. By a series of process, alloys containing 75 wt% Ni and 20 wt% Fe were produced. From the results, the reduction mechanism of nickel oxide and iron oxide were investigated.

Experimental Investigation of Ultrasonic Vibration Assisted Turning of 304 Austenitic Stainless Steel

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Ping Zou

2015-01-01

vibration method is employed to scheme out a machining system of ultrasonic vibration assisted turning (MS-UAT. The experiments for turning the workpiece of ASS 304 are conducted with and without ultrasonic vibration using the designed MS-UAT, and then the 3D morphology evaluation parameters Sa and Sq are applied to characterize and analyse the machined surface. The experimental results obtained demonstrate that the process parameters in UAT of ASS 304 have obvious effect on the 3D surface topography and surface roughness of machined workpiece, and the appropriate choice of various process parameters, including ultrasonic amplitude, feed rate, depth of cut, and cutting speed, can enhance the machined surface quality efficiently to make the machining effect of UAT much better than that of CT.

Calculated and experimental research of WWER-1000 assembly vibration and fretting damage

International Nuclear Information System (INIS)

Drozdov, Y.; Afanasyev, A.; Makarov, V.; Tutnov, A.; Tutnov, A.; Alekseev, E.

2008-01-01

The report covers the methods and results of the latest analytical and experimental studies of fretting corrosion and natural vibrations of a WWER-1000 reactor fuel assemblies (FA). The process of fretting-corrosion was investigated using a multi-specimen facility that simulated fragments of fuel rod-to-spacer grid and lower support grid mating units. A computational model was developed for vibrations in the mechanical system of a fuel rod fragment and a spacer grid fragment. A calculational and experimental modal analysis of a FA was performed. Natural frequencies, modes and decrements of FA vibrations were determined and a satisfactory coincidence of analytical and experimental results was obtained. The assessment of fretting-corrosion process dynamics was made and its dependences on operational factors were obtained. (authors)

Resonance tunneling electron-vibrational spectroscopy of polyoxometalates.

Science.gov (United States)

Dalidchik, F I; Kovalevskii, S A; Balashov, E M

2017-05-21

The tunneling spectra of the ordered monolayer films of decamolybdodicobaltate (DMDC) compounds deposited from aqueous solutions on HOPG were measured by scanning tunnel microscopy in air. The DMDC spectra, as well as the tunneling spectra of other polyoxometalates (POMs), exhibit well-defined negative differential resistances (NDRs). The mechanism of formation of these spectral features was established from the collection of revealed NDR dependences on the external varying parameters and found to be common to all systems exhibiting Wannier-Stark localization. A model of biresonance tunneling was developed to provide an explanation for the totality of experimental data, both the literature and original, on the tunneling POM probing. A variant of the tunneling electron-vibrational POM spectroscopy was proposed allowing the determination of the three basic energy parameters-energy gaps between the occupied and unoccupied states, frequencies of the vibrational transitions accompanying biresonance electron-tunneling processes, and electron-vibrational interaction constants on the monomolecular level.

Control aid for xenon vibration in reactor

International Nuclear Information System (INIS)

Kanekawa, Takashi.

1990-01-01

In the present invention, the control operation for suppressing xenon vibrations in a reactor is aided for saving forecasting analysis and operator's skills. That is, parameters to be controlled for the suppression of xenon vibrations are power distribution, iodine distribution and xenon distribution. But what can be observed by operaters by the conventional fast overtone method is only the output distribution. In the present invention, the output level of the reactor core is always observed. Then, mathematical processings are conducted for the iodine distribution, the xenon distribution and the power distribution in the reactor core based on the histeresis of the parameters obtained by the measurement using physical constants and reactor design data. The xenon vibration control is aided by displaying the change with time of the distortion in axial direction. Accordingly, operators can always recognize the axial distortion of the power distribution, the iodine distribution and the xenon distribution. (I.S.)

Resonant vibration control of three-bladed wind turbine rotors

DEFF Research Database (Denmark)

Krenk, Steen; Svendsen, Martin Nymann; Høgsberg, Jan Becker

2012-01-01

Rotors with blades, as in wind turbines, are prone to vibrations due to the flexibility of the blades and the support. In the present paper a theory is developed for active control of a combined set of vibration modes in three-bladed rotors. The control system consists of identical collocated...... to influence of other nonresonant modes. The efficiency of the method isdemonstrated byapplication to a rotor with 42 m blades, where the sensor/actuator system is implemented in the form of an axial extensible strut near the root of each blade. The load is provided by a simple but fully threedimensional...... correlated wind velocity field. It is shown by numerical simulations that the active damping system can provide a significant reduction in the response amplitude of the targeted modes, while applying control moments to the blades that are about 1 order of magnitude smaller than the moments from the external...

High-Temperature Vibration Damper

Science.gov (United States)

Clarke, Alan; Litwin, Joel; Krauss, Harold

1987-01-01

Device for damping vibrations functions at temperatures up to 400 degrees F. Dampens vibrational torque loads as high as 1,000 lb-in. but compact enough to be part of helicopter rotor hub. Rotary damper absorbs energy from vibrating rod, dissipating it in turbulent motion of viscous hydraulic fluid forced by moving vanes through small orifices.

Multi-objective genetic algorithm optimization of 2D- and 3D-Pareto fronts for vibrational quantum processes

International Nuclear Information System (INIS)

Gollub, C; De Vivie-Riedle, R

2009-01-01

A multi-objective genetic algorithm is applied to optimize picosecond laser fields, driving vibrational quantum processes. Our examples are state-to-state transitions and unitary transformations. The approach allows features of the shaped laser fields and of the excitation mechanisms to be controlled simultaneously with the quantum yield. Within the parameter range accessible to the experiment, we focus on short pulse durations and low pulse energies to optimize preferably robust laser fields. Multidimensional Pareto fronts for these conflicting objectives could be constructed. Comparison with previous work showed that the solutions from Pareto optimizations and from optimal control theory match very well.

Fiber-Optic Vibration Sensor Based on Multimode Fiber

Directory of Open Access Journals (Sweden)

I. Lujo

2008-06-01

Full Text Available The purpose of this paper is to present a fiberoptic vibration sensor based on the monitoring of the mode distribution in a multimode optical fiber. Detection of vibrations and their parameters is possible through observation of the output speckle pattern from the multimode optical fiber. A working experimental model has been built in which all used components are widely available and cheap: a CCD camera (a simple web-cam, a multimode laser in visible range as a light source, a length of multimode optical fiber, and a computer for signal processing. Measurements have shown good agreement with the actual frequency of vibrations, and promising results were achieved with the amplitude measurements although they require some adaptation of the experimental model. Proposed sensor is cheap and lightweight and therefore presents an interesting alternative for monitoring large smart structures.

The effect of material productivity on scrap reduction on aluminum reduction pot process

Science.gov (United States)

Huda, L. N.

2018-02-01

Scrap in the production process is defined as part of production that can not be accepted as the final product due to production failure. The amount of scarp occurring in the reduction pot production process of one of the aluminum smelting furnaces exceeds the acceptance standard of 5 to 10%. This affects the amount of production produced. The purpose of this study is to reduce the amount of scrap produced to increase the productivity of the materials used. The solution is carried-out by making improvements using Lean Six Sigma method. In the initial calculation, material productivity ranged from 0.88. Based on the study, the factors that cause the high amount of scrap produced is the use of Na2O which is inserted into the alumina is different in size and the influence of noise that occurs in pots that are difficult to control. The analysis base on Lean Six Sigma obtained process cycle efficiency (PCE) equal to 86,92% for actual condition. Process improvement is carried-out through define, measure, analyze, improve and control procedure on Na2O feeding process and PCE value decrease 6,05%. This indicates that increased process capability will reduce scrap. A decrease in scrap amount of about 6% will be able to increase material productivity by 0.05%. This indicates that continuous process control is needed to decrease the number of scraps and increase productivity.

EFFECT OF VIBRATION AND HEAT COMBINATION ON PRIMARY DYSMENORRHEA

Directory of Open Access Journals (Sweden)

M. Hoseini

2015-03-01

Full Text Available Background: Primary dysmenorrhoea is a common, idiopathic, chronic pelvic pain syndrome, with unknown aetiology which ‎about 50% of women with regular menstrual period suffer. This study was designed to determine the effect of vibration and heat on primary dysmenorrhea. Materials and Methods: In this clinical trial, 75 female students aged 18-22 years old were evaluated for two menstrual cycles. At the first cycle the participants received the routine pain-relief method (synthetic or herbal medicine and traditional remedies. At the second cycle for each participant combined vibration-heat device was applied for ten minutes during ‎menstrual pain. The average of perceived leg pain, lumbar pain and abdominal pain scores at two cycles were determined. The data were analyzed based on Wilcoxon and T tests by using SPSS (v 16.0 for Windows. Results: The average of all perceived pain scores at two cycles were significantly different before pain relief and after both routine methods and using the device (p<0.001. Those were more significantly reduced after using the device in comparison of using routine methods (p<0.001. Conclusion: Since “vibration-heat” is an effective pain relief method, it can be used as a complementary alternative medicine in primary dysmenorrhea reduction.