Comparing orthogonal force and unidirectional strain component processing for tool condition monitoring

Signal processing using orthogonal cutting force components for tool condition monitoring has established itself in literature. In the application of single axis strain sensors however a linear combination of cutting force components has to be processed in order to monitor tool wear. This situation may arise when a single axis piezoelectric actuator is simultaneously used as an actuator and a sensor, e.g. its vibration control feedback signal exploited for monitoring purposes. The current paper therefore compares processing of a linear combination of cutting force components to the reference case of processing orthogonal components. Reconstruction of the dynamic force acting at the tool tip from signals obtained during measurements using a strain gauge instrumented tool holder in a turning process is described. An application of this dynamic force signal was simulated on a filter-model of that tool holder that would carry a self-sensing actuator. For comparison of the orthogonal and unidirectional force component tool wear monitoring strategies the same time-delay neural network structure has been applied. Wear-sensitive features are determined by wavelet packet analysis to provide information for tool wear estimation. The probability of a difference less than 5 percentage points between the flank wear estimation errors of above mentioned two processing strategies is at least 95 %. This suggests the viability of simultaneous monitoring and control by using a self-sensing actuator.     

Primary beneficiation of tantalite using magnetic separation and acid leaching

Primary beneficiation was successfully performed prior to dissolution of manganotantalite （sample A） and ferrotantalite （sample C） samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and -2wt% each of Nb205 and Ta205 were removed from sample C （ferrotantalite） using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe203 and TiO2, respectively, and -2wt% each of NbEOs and Ta2O5 were removed from sample A （manganotantalite）. A temperature of 50℃ and a leaching time of 3 h in the presence of concentrated HESOa were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% ThO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and Ta2O5, respectively.     

The electric quadrupole contribution to the circular birefringenceof nonmagnetic anisotropic chiral media: a circular waveguide experiment

Constitutive relations which include electric quadrupole terms, in addition to electric and magnetic dipole terms, are used to describe the “optical activity”, in particular the circular birefringence, of an anisotropic chiral medium which is nonmagnetic. The resulting permittivity and chirality tensors are then used to predict the rotation of the polarization plane of a linearly polarized wave propagating in a circular waveguide filled with the medium. The numerical predictions were tested by measurements between 2.4 and 4 GHz on a 2 m long artificial crystal in a circular waveguide and it was found that the rotation of the polarization was within 13% of the predicted value-good agreement after considering the possible sources of error. It is thus established that the effect of electric quadrupoles must be included when modeling the optical activity of anisotropic chiral media in the long wavelength regime. The anisotropic chiral media which are dealt with here can be classified according to the crystallographic point groups to which they belong, and they may therefore also be considered to be artificial crystals     

A sensitive seminested PCR method for the detection of Shigella in spiked environmental water samples

A rapid seminested polymerase chain reaction (PCR) method for the specific, sensitive detection of virulent Shigella spp. in spiked environmental water samples was developed. A set of primers specific for the invasion plasmid antigen gene (ipaH) of virulent Shigella spp. and enteroinvasive Escherichia coli produced a 620-bp fragment that was used as template for the seminested primer pair delineating a 401-bp fragment. By using agarose gel electrophoresis for detection of the seminested PCR-amplified products, a detection limit of 1.6 x 10(3) cfu S. flexneri was obtained with amplification reactions from crude bacterial lysates. The PCR procedure coupled with an enrichment culture incubated for 6 h detected as few as 1.6 S. flexneri organisms in pure culture. Treated sewage, ground, surface and drinking water samples collected from various sources were seeded with S. flexneri and incubated in GN broth for 6 h before detection by seminested PCR. A detection limit lower than 14 cfu/ml was achieved in some water samples. The results indicate that the described seminested PCR has the advantage of a rapid turnaround time and it fulfills the requirements of sensitivity and specificity for use in an environmental laboratory.     

Experimental investigation of the effects of heat release on mixing processes and flow structure in a high-speed subsonic turbulent H2 jet

In this paper, we explore the effects of heat release on mixing and flow structure in a high-speed subsonic turbulent H₂ jet in an air coflow. Heat release effects are determined from the comparison of nonreacting and reacting jet behavior, boundary conditions being identical in both cases. Experiments are performed in a wind tunnel specifically designed for this purpose. Planar laser induced fluorescence on OH radicals and on acetone (seeded in the hydrogen jet) are used to characterize the cartography of scalars, and laser Doppler velocimetry is used to characterize velocity profiles in the far field of the H₂ jet. Results show significant effects of heat release on mixing and flow structure, indicating an overall reduction of mixing and entrainment in the reacting jet compared to the nonreacting jet. First, a change is observed in the orientation of coherent structures originating from Kelvin-Helmholtz type instabilities, and responsible for air entrainment within the jet, which appear “flatter” in the jet flame. Then, the flame length is increased over what would be predicted from the intersection of the mean stoichiometric contour with the centerline of the nonreacting jet. And finally, the longitudinal average velocity decrease along the jet axis is quicker in the nonreacting jet, and nondimensional transverse velocity fluctuations are about half as high in the reacting jet as in the nonreacting jet, indicating a reduction of the turbulence intensity of the flow in this direction in the jet flame.     

LT-GaAs with high breakdown strength at low temperature for power MISFET applications

Low temperature grown GaAs has been fabricated containing a limited amount of excess arsenic. The material has a low conductivity in the order of 100KΩ cm, due to hopping in a deep donor band. This σ-LT-GaAs was grown reproducibly by using the lattice mismatch as the primary parameter for substrate temperature calibration. Breakdown fields, in the order of 100kV/cm, are observed for planar structures and increased at low measurement emperatures. Low hopping conductivity and high breakdown field are also observed in the lossy dielectric metal-insulator-semiconductor field-effect transistor device using σ-LT-GaAs as a surface layer. The record radio frequency power density of 4.0W/mm at 77K is extracted from the dc output characteristics.     

Effect of rolipram and dibutyryl cyclic AMP on resequestration of cytosolic calcium in FMLP-activated human neutrophils

Fluorescence microscopic methods have been used to characterize the cell cycle of Bacillus subtilis at four different growth rates. The data obtained have been used to derive models for cell cycle progression. Like that of Escherichia coli, the period required by B. subtilis for chromosome replication at 37 degrees C was found to be fairly constant (although a little longer, at about 55 min), as was the cell mass at initiation of DNA replication. The cell cycle of B. subtilis differed from that of E. coli in that changes in growth rate affected the average cell length but not the width and also in the relative variability of period between termination of DNA replication and septation. Overall movement of the nucleoid was found to occur smoothly, as in E. coli, but other aspects of nucleoid behavior were consistent with an underlying active partitioning machinery. The models for cell cycle progression in B. subtilis should facilitate the interpretation of data obtained from the recently introduced cytological methods for imaging the assembly and movement of proteins involved in cell cycle dynamics.     

1 W/mm power pseudomorphic HFET with optimised recess technology

The authors report record DC characteristics and RF performance of a power double heterostructure (DH) pseudomorphic (PM) InGaAs quantum well HFET. The device, with a 0.3×70 μm² gate, exhibits an intrinsic transconductance as high as 720 mS/mm, a maximum current density of ~1 A/mm and delivers a state-of-the-art output power density of 1 W/mm with 5.7 dB linear gain and 38% power added efficiency at 33 GHz. A detailed analysis of the technological aspects and electrical characteristics of the device is proposed to explain these excellent performances