Real time and an in-process measuring system for the grinding process cylindrical workpieces using Kalman filtering

This paper introduces an in-process measurement system that does not pause during the machining processes. The system could result in enhanced productivity and quality control in manufacturing processes that use a surface grinding spindle. For the gauging sensor of the measurement system, we propose an eddy-current sensor because it is a noncontact type, which uses an eddy current induced when a metallic material is placed in a high-frequency electromagnetic field. Also, it is very insensitive to other kinds of interference such as cutting fluids, coolants, contact pressure, and wear at the contact point. For data analysis, the measurement system was modeled as a linearized discrete form, and the states with noises were estimated by an extended Kalman filter. Validation of this system was performed through a simulation and an experiment.     

Stereoisomers of P. aeruginosa autoinducer analog to probe the regulator binding site

Quorum sensing (QS) regulates the production of virulence factors and the maturation of biofilms in many bacteria, including Pseudomonas aeruginosa. The QS cascade is activated by the interaction of bacterial signaling molecules, called autoinducers (AIs), with their corresponding regulatory proteins. Here, we report a series of studies to define the stereochemical preferences of synthetic agonists and perform docking studies to understand the microenvironment of the binding site in P. aeruginosa QS regulators. One of the key findings of this work is that the ring structure and the absolute and relative stereochemistries of the amide and hydroxyl groups dictate the agonist activity. This study aids in determining important structural and stereochemical characteristics necessary for interaction with the QS regulatory proteins, thus expanding our understanding of their inducer binding sites.     

Nonlinear instability of an annular liquid sheet exposed to gas flow

Nonlinear instability and breakup of an annular liquid sheet has been modeled in this paper. The liquid sheet is considered to move axially and is exposed to co-flowing inner and outer gas streams. Also, the effect of outer gas swirl on sheet breakup has been studied. In the developed model a perturbation expansion method has been used with the initial magnitude of the disturbance as the perturbation parameter. This is a comprehensive model in that other geometries of planar sheet and a coaxial jet can be obtained as limiting cases of very large inner radius and inner radius equal to zero, respectively. In this temporal analysis, the effect of liquid Weber number, initial disturbance amplitude, inner gas-to-liquid velocity ratio, outer gas-to-liquid velocity ratio and outer gas swirl strength on the breakup time is investigated. The model is validated by comparison with earlier analytical studies for the limiting case of a planar sheet as well as with experimental data of sheet breakup length available in literature. It is shown that the linear theory cannot predict breakup of an annular sheet and the developed nonlinear model is necessary to accurately determine the breakup length. In the limiting case of a coaxial jet, results show that gas swirl destabilizes the jet, makes helical modes dominant compared to the axisymmetric mode and decreases jet breakup length. These results contradict earlier linear analyses and agree with experimental observations. For an annular sheet, it is found that gas flow hastens the sheet breakup process and shorter breakup lengths are obtained by increasing the inner and the outer gas velocity. Axially moving inner gas stream is more effective in disintegrating the annular sheet compared to axially moving outer gas stream. When both gas streams are moving axially, the liquid sheet breakup is quicker compared to that with any one gas stream. In the absence of outer gas swirl, the axisymmetric mode is the dominant instability mode. However, when outer gas flow has a swirl component higher helical modes become dominant. With increasing outer gas swirl strength, the maximum disturbance growth rate increases and the most unstable circumferential wave number increases resulting in a highly asymmetric sheet breakup with shorter breakup lengths and thinner ligaments.     

Intercalated poly(vinylidene fluoride)/clay nanocomposites: Structure and properties

The preparation and characterization of melt‐intercalated poly(vinylidene fluoride) (PVDF)/clay nanocomposites are reported. Organophilic clay (clay treated with dimethyl dihydrogenated tallow quaternary ammonium chloride) was used for the nanocomposite preparation. The composites were characterized with X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). XRD results indicated the intercalation of the polymer in the interlayer spacing. The incorporation of clay in PVDF resulted in the β form of PVDF. DSC nonisothermal curves showed an increase in the melting and crystallization temperatures along with a decrease in crystallinity. Isothermal crystallization studies show an enhanced rate of crystallization with the addition of clay. DMA indicated significant improvements in the storage modulus over a temperature range of ?100 to 150 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 31–38, 2003     

Copolyester/layered silicate nanocomposites: The effect of the molecular size and molecular structure of the intercalant on the structure and viscoelastic properties of the nanocomposites

The preparation of poly(ethylene glycol‐co‐cyclohexane‐1,4‐dimethanol terephthalate)/layered silicate nanocomposites via a melt‐intercalation technique is reported. Layered silicates modified with different alkyl ammonium intercalants have been used for this purpose. A comparison is made between carefully chosen pairs of the nanocomposites, the choice depending on the cation‐exchange capacity or the intercalant concentration of the organically modified montmorillonite, to study the effects of the molecular size and molecular structure of the intercalant. The structure of the nanocomposites is characterized with wide‐angle X‐ray diffraction. The presence of well‐defined diffraction peaks and an observed increase in the interlayer spacing in the nanocomposites imply the formation of an intercalated hybrid. To investigate the viscoelastic behavior, these nanocomposites are also subjected to dynamic mechanical analysis. The dynamic mechanical properties show an increase in the storage modulus of the nanocomposites over the entire temperature range studied (except in the transition region from 68 to 78 °C) in comparison with that of the pristine polymer. The size of the intercalant molecule and the presence of functional groups capable of forming favorable interactions with the polymer govern the amount of polymer infiltrating the clay gallery space and control the increase in the modulus of the nanocomposite. The tan δ peak signifying the glass‐transition temperature shifts to lower temperatures in the nanocomposites. Interestingly, the nanocomposites show less damping than the pristine polymer. This behavior is understood in terms of the confinement of the polymer chains in the clay interlayer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3102–3113, 2003     

Molecular dynamics of copolyester/clay nanocomposites as investigated by viscoelastic and dielectric analysis

We have investigated the molecular dynamics of poly(ethylene glycol-co-cycloxeane-1,4-dimethanol terephthalate) (PETG) nanocomposites based on a organically modified layered silicate. Intercalated nanocomposites were prepared by melt compounding technique as evidenced from the X-ray diffraction and transmission electron microscopy studies. Two relaxation processes were observed in pure PETG as well as in the nanocomposites. The low-temperature β-process was assigned to the local motions of CO polar groups and the α-process was due to the glass-rubber transition or the segmental relaxations associated with the polymer chain backbone. Presence of layered silicates accelerated α-relaxation dynamics in the nanocomposites accompanied by a depression in T_g which was attributed to the reduced intermolecular cooperativity between intercalated polymers chains. Additionally, a direct comparison between the viscoelastic and dielectric studies shows excellent agreement between the accelerated α dynamics of the nanocomposites. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2539–2555, 2008     

Lopsided spiral galaxies

The light distribution in the disks of many galaxies is ‘lopsided’ with a spatial extent much larger along one half of a galaxy than the other, as seen in M101. Recent observations show that the stellar disk in a typical spiral galaxy is significantly lopsided, indicating asymmetry in the disk mass distribution. The mean amplitude of lopsidedness is 0.1, measured as the Fourier amplitude of the m=1$m=1$ component normalized to the average value. Thus, lopsidedness is common, and hence it is important to understand its origin and dynamics. This is a new and exciting area in galactic structure and dynamics, in contrast to the topic of bars and two-armed spirals (m=2)$(m=2)$ which has been extensively studied in the literature. Lopsidedness is ubiquitous and occurs in a variety of settings and tracers. It is seen in both stars and gas, in the outer disk and the central region, in the field and the group galaxies. The lopsided amplitude is higher by a factor of two for galaxies in a group.     

Electron-beam-induced conduction in fluorinated ethylene propylene copolymer and its acrylonitrile graft copolymer

Electron-beam-induced conductivity (EBIC) studies were carried out on fluorinated ethylene propylene copolymer (FEP) and its acrylonitrile graft copolymer (FEP-g-AN). The current transport parallel to the surface under the influence of an electron beam of medium energy (6–30 keV) is reported. The gain in EBIC is calculated and its characteristic variation as a function of beam energy is studied. Minima in the gain versus energy curves have been obtained around 21 keV for FEP, 12 and 18 keV for FEP-g-AN, and 12 keV for polyacrylonitrile (PAN). This behavior is explained by assuming the existence of electron trapping bands close to the surface, at characteristic distances below the surface of the polymeric film corresponding to the range of incident electrons. Gains of the order of 5, 12, and 30 have been obtained respectively for FEP, FEP-g-AN, and PAN for the maximum energy of incident electrons used.     

A domino approach (hydrolysis/dehydrohalogenation/Heck coupling) for the synthesis of styrene sulfonate salts

A domino approach of hydrolysis/dehydrohalogenation/Heck coupling was used to synthesize styrene sulfonate salts from iodoarenes and chloroethanesulfonyl chloride in good to excellent yields. Methodology was applicable for heterocyclic as well as disubstituted iodoarenes. Some of the key features of this synthetic methodology include the use of phosphine free catalytic system, water as an environmentally friendly solvent, short reaction times, and absence of additives.