Continuous wavelet transform and neural network for condition monitoring of rotodynamic machinery

This paper describes a novel method of rotodynamic machine condition monitoring using a wavelet transform and a neural network. A continuous wavelet transform is applied to the signals collected from accelerometer. The transformed images are then extracted as unique characteristic features relating to the various types of machine conditions. In the experiment, four types of machine operating conditions have been investigated: a balanced shaft; an unbalanced shaft, a misaligned shaft and a defective bearing. The back propagation neural network (BPNN) is used as a tool to evaluate the performance of the proposed method. The experimental results result in a recognition rate of 90 percent

Design of an instrumented smart cutting tool and its implementation and application perspectives

This paper presents an innovative design of a smart cutting tool, using two surface acoustic wave (SAW) strain sensors mounted onto the top and the side surface of the tool shank respectively, and its implementation and application perspectives. This surface acoustic wave-based smart cutting tool is capable of measuring the cutting force and the feed force in a real machining environment, after a calibration process under known cutting conditions. A hybrid dissimilar workpiece is then machined using the SAW-based smart cutting tool. The hybrid dissimilar material is made of two different materials, NiCu alloy (Monel) and steel, welded together to form a single bar; this can be used to simulate an abrupt change in material properties. The property transition zone is successfully detected by the tool; the sensor feedback can then be used to initiate a change in the machining parameters to compensate for the altered material properties.The UK Technology Strategy Board (TSB) for supporting this research (SEEM Project, contract No. BD266E

Metallic Triple Beam Resonator with Thick-film Printed Drive and Pickup

A triple beam resonator fabricated in 430S17 stainless steel with thick-film piezoelectric elements to drive and detect the vibrations is presented. The resonator substrate was fabricated by a simultaneous, double-sided photochemical etching technique and the thick-film piezoelectric elements were deposited by a standard screen-printing process. The combination of these two batch-fabrication processes provides the opportunity for mass production of the device at low cost. The resonator, a dynamically balanced triple beam tuning fork (TBTF) structure 23.5 mm long and 6.5 mm wide, has a favoured mode at 4.96 kHz with a Q-factor of 3630 operating in air

Ion Charge States in Halo CMEs: What can we Learn about the Explosion?

We describe a new modeling approach to develop a more quantitative understanding of the charge state distributions of the ions of various elements detected in situ during halo Coronal Mass Ejection (CME) events by the Advanced Composition Explorer (ACE) satellite. Using a model CME hydrodynamic evolution based on observations of CMEs propagating in the plane of the sky and on theoretical models, we integrate time dependent equations for the ionization balance of various elements to compare with ACE data. We find that plasma in the CME ``core'' typically requires further heating following filament eruption, with thermal energy input similar to the kinetic energy input. This extra heating is presumably the result of post eruptive reconnection. Plasma corresponding to the CME ``cavity'' is usually not further ionized, since whether heated or not, the low density gives freeze-in close the the Sun. The current analysis is limited by ambiguities in the underlying model CME evolution. Such methods are likely to reach their full potential when applied to data to be acquired by STEREO when at optimum separation. CME evolution observed with one spacecraft may be used to interpret CME charge states detected by the other.Comment: 20 pages, accepted by Ap

Daily Mutual Fund Flows and Redemption Policies

We examine how redemption policies affect daily fund flows in open-end mutual funds. Since short-term trading of fund shares, as manifested in daily fund flows, can have an adverse impact on returns to the fund’s shareholders, mutual funds might find it desirable to discourage short-term trading through the use of redemption fees. However, if daily fund flows are due to fund shareholders’ legitimate liquidity demands, the redemption fee would have little effect on daily fund flows and possibly adversely affect fund shareholders by imposing a liquidity cost on them. We find that the likelihood of a fund charging a redemption fee is largely a function of its overall fee structure. We also use a sample of funds that imposed redemption fees to examine whether the distribution of daily fund flows changes after the initiation of the redemption fee. We find that the redemption fee is an effective tool in controlling the volatility of fund flows

Manipulation of Beams of Ultra-relativistic Electrons to Create Femtosecond X-ray Pulses

The research proposed here is expected to result in a crucial component used in a next-generation X-ray source. Typical conventional high-brightness X-ray sources (so-called synchrotron lightsources) are up to 30 football fields in size. Our group uses a novel technique based on ultrahigh-power lasers to develop a similar source that can readily fit into a single, university-scale laboratory. More specifically, the research conducted within this proposal will be concerned with the manipulation of beams of ultra-relativistic electrons, (electrons that move with almost the speed of light) with the goal to focus the particles into an area that is smaller than the diameter of a human hair. X-ray sources are commonly used to resolve the molecular constituents of matter on the atomic-scale (i.e. to spatially resolve molecular structures and dynamics on their natural length and time scale). This requires X-ray pulses with Angström wavelengths (less than a billionth meter, 10^(-10) m) and femtosecond (a millionth of a billionth second, 10^(-15) s) duration

Manipulation of Beams of Ultra-relativistic Electrons to Create Femtosecond X-ray Pulses

The research proposed here is expected to result in a crucial component used in a next-generation X-ray source. Typical conventional high-brightness X-ray sources (so-called synchrotron lightsources) are up to 30 football fields in size. Our group uses a novel technique based on ultrahigh-power lasers to develop a similar source that can readily fit into a single, university-scale laboratory. More specifically, the research conducted within this proposal will be concerned with the manipulation of beams of ultra-relativistic electrons, (electrons that move with almost the speed of light) with the goal to focus the particles into an area that is smaller than the diameter of a human hair. X-ray sources are commonly used to resolve the molecular constituents of matter on the atomic-scale (i.e. to spatially resolve molecular structures and dynamics on their natural length and time scale). This requires X-ray pulses with Angström wavelengths (less than a billionth meter, 10^(-10) m) and femtosecond (a millionth of a billionth second, 10^(-15) s) duration

Investigating ion recombination effects in a liquid‐filled ionization chamber array used for IMRT QA measurements

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134893/1/mp6822.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134893/2/mp6822_am.pd

Spatially Dependent Heating and Ionization in an ICME Observed by Both ACE and Ulysses

The 2005 January 21 interplanetary coronal mass ejection (ICME) observed by multiple spacecraft at L1 was also observed from January 21-February 4 at Ulysses (5.3 AU). Previous studies of this ICME have found evidence suggesting that the flanks of a magnetic cloud like structure associated with this ICME were observed at L1 while a more central cut through the associated magnetic cloud was observed at Ulysses . This event allows us to study spatial variation across the ICME and relate it to the eruption at the Sun. In order to examine the spatial dependence of the heating in this ICME, we present an analysis and comparison of the heavy ion composition observed during the passage of the ICME at L1 and at Ulysses . Using SWICS, we compare the heavy ion composition across the two different observation cuts through the ICME and compare it with predictions for heating during the eruption based on models of the time-dependent ionization balance throughout the event.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98582/1/0004-637X_760_2_105.pd

The Physics of Supernova Remnant Blast Waves. I. Kinematics of DEM L71 in the Large Magellanic Cloud

We present the results from Fabry-Perot imaging spectroscopy of the Balmer-dominated supernova remnant DEM L71 (0505-67.9) in the LMC. Spectra extracted from the entire circumference of the blast wave reveal the broad and narrow component H-alpha line emission characteristic of non-radiative shocks in partially neutral gas. The new spectra of DEM L71 include portions of the rim that have not been previously observed. We find that the broad component width varies azimuthally along the edge of DEM L71, ranging from 450+/-60 km/s along the eastern edge to values as high as 985 (+210)(-165) km/s along the faint western edge. In part of the faint northern rim the broad component is not detected, possibly indicating a lower density in these regions and/or a broad component width in excess of 1000 km/s. Between the limits of zero and full electron-ion temperature equilibration at the shock front, the allowed range of shock velocities is 430-560 km/s along the east rim and 700-1250 km/s along other parts of the blast wave. The H-alpha broad-to-narrow flux ratios vary considerably around the remnant, ranging from 0.4 to 0.8. These ratios lie below the values predicted by our shock models. We find that narrow component H-alpha emission from a cosmic ray precursor may be the cause of the discrepancy. The least decelerated portions of the blast wave (i.e., regions excluding the brightest filaments) are well characterized by Sedov models with a kinetic energy E_51= (0.37+/-0.06)*D_50**(5/2), where D_50 is the LMC distance in units of 50 kpc. The corresponding age for DEM L71 is (4360+/-290)*D_50 yr. This is the first time that velocity information from the entire blast wave has been utilized to study the global kinematics of a non-radiative SNR at a known distance.Comment: 21 pages, including 8 postscript figures and 4 tables, LaTeX, accepted to ApJ; see companion pape