A wavelet-based procedure for process fault detection

To detect faults in a time-dependent process, we apply a discrete wavelet transform (DWT) to several independently replicated data sets generated by that process. The DWT can capture irregular data patterns such as sharp "jumps" better than the Fourier transform and standard statistical procedures without adding much computational complexity. Our wavelet coefficient selection method effectively balances model parsimony against data reconstruction error. The few selected wavelet coefficients serve as the "reduced-size" data set to facilitate an efficient decision-making method in situations with potentially large-volume data sets. We develop a general procedure to detect process faults based on differences between the reduced-size data sets obtained from the nominal (in-control) process and from a new instance of the target process that must be tested for an out-of-control condition. The distribution of the test statistic is constructed first using normal distribution theory and then with a new resampling procedure called "reversed jackknifing" that does not require any restrictive distributional assumptions. A Monte Carlo study demonstrates the effectiveness of these procedures. Our methods successfully detect process faults for quadrupole mass spectrometry samples collected from a rapid thermal chemical vapor deposition process     

Further studies on polyamides from bisacid a2

Earlier work on the low temperature solution polyamidation of bisacid A2 has raised a number of structural problems. Work carried out more recently showed that the problem of apparent nonisostoichiometry could be reasonably satisfactorily explained. The present paper reports the synthesis and investigates the properties of a further series of polyamides based upon Bisacid A2. More importantly, however, a detailed characterization and evaluation of the new polymers with respect to their structures is presented. This enabled us to compare the various structures in the light of the experimental evidence provided by a number of analytical and spectroscopic techniques, solution behavior, molecular weight, and thermal, morphological, and mechanical properties. Some work was also done on the effect of incorporating a small amount of a trifunctional monomer into the polyamide system.     

Fatty acid composition of phospholipids and neutral lipids during embryonic and early larval development in Atlantic herring (Clupea harengus,L.)

The fatty acid compositions of total polar and total neutral lipids of Atlantic herring eggs and larvae were determined immediately before fertilization, after fertilization and at various times during subsequent embryonic and early larval development. Within 3 hr after fertilization the percentage of total PUFA in neutral lipid decreased from 33% to 20%, with a reciprocal increase in monoenes. Thereafter the percentage of PUFA in the neutral lipids increased progressively, attaining the original level in ripe eggs by the time of yolk sac absorption. During the larval stages the percentage of PUFA continued to increase in the neutral lipid, reaching almost 44% of the total by day 32 after fertilization, although it was reduced to 32% by day 36. The percentage of monoenes in the neutral lipid displayed a progressive decrease during the whole period of development from 3 hr after fertilization. Throughout all the developmental periods the fatty acid composition of total polar lipids remained essentially constant. The polar lipids of the yolk sac displayed virtually the same fatty acid composition as the larval bodies, but the neutral lipids of the yolk sac were low in PUFA compared to the larval bodies. The results are discussed with reference to changes in lipid class composition during development. The conservation of high levels of PUFA in lipids during embryogenesis and early larval development reflects the importance of these fatty acids during development.     

Dynamics of hydrated iron(II) cations in nafion polymer membranes

Mössbauer studies of Fe²⁺ in water-soaked nafion polymer membranes in the temperature range between 90 K and 250 K have been performed. Above a critical temperature (～ 180 K) the spectra exhibit both elastic narrow absorption lines and quasielastic broad lines. These spectra are typical of bounded diffusion phenomena observed by Mössbauer spectroscopy in macromolecular systems like haemoglobin, myoglobin and ferritin. Similar spectral shapes have been observed by quasielastic neutron scattering from water in nafion membranes. Within 50 K above the critical temperature the total Mössbauer absorption area decreases by an order of magnitude whereas the narrow absorption line decreases by two orders of magnitude. The results are interpreted in terms of bounded diffusive motion of the iron. Using a model based on overdamped harmonically bound Brownian motion, the essential parameters of the iron motion can be derived as a function of temperature. The iron motion most probably reflects the motion of a large Fe²⁺ complex, e.g. Fe(H₂O)²⁺₆, which is attached to the polymer side chains via the sulphonic group.     

ALUM SHALE BITUMEN MATURATION AND MIGRATION: IMPLICATIONS FOR GOTLAND'S OIL

Thermal maturation of Swedish Alum Shale kerogen and bitumen has been determined from core samples from Eastern and Central Sweden. In samples from Eastern Sweden (Öland and Gotland), the kerogen and bitumen are thermally immature with respect to petroleum generation. In some areas of Central Sweden (Närke, ÖstergÖtland, and Kinnekulle in VästergÖtland), the kerogen is immature, whereas the bitumen is marginally mature to mature. In other areas of Central Sweden (Halleberg-Hunneberg in VästergÖtland), the kerogen is supermature and the bitumen mature. This suggests that bitumen from a mature source-rock has migrated into the Alum Shales of Central Sweden. Migration in Central Sweden is further evidenced by the occurrence of obviously-migrated bituments in vugs and voids in the organicpoor Ordovician limestone overlying the Alum Shale in Central Sweden, and in concretions within the Alum Shale itself. Based on biomarker distributions of extracted bitumen, Alum Shale kerogen pyrolysate and obviously-migrated oils, and the fact that the Alum Shale in most of the areas studied is the only petroleum source-rock extant, it is suggested that the migrated bitumen in Central Sweden is from the Alum Shale itself. Bitumen has migrated from areas where the Alum Shale is in close proxmity to Permo-Carboniferous intrusions, such as Halleberg-Hunneberg, into nearby areas such as Närke and ÖstergÖtland, where there is no evidence of intrusion and the indigenous organic matter is thermally immature. Other areas, where Alum Shales were associated with intrusions and consequently sourced oil, may have been eroded away. There are producing wells on the island of Gotland, where the Alum Shale is also thermally immature. It is therefore assumed that heating which was responsible for generating Gotland's oil was very localized (such as by an intrusion) or that the oil has migrated from a thermally moremature, distant area. On the basis of reservoir rock porosity, and the fact that the Alum Shale of Gotland contains no migrated component, localized heating is favored.     

Fine-line conductor manufacturing using drop-on demand PZT printingtechnology

An emerging selective metallization process to fabricate fine-line conductors based on drop-on-demand (DOD) ink jet printing and novel nano-particle fluid suspensions (NPFS) was studied. The suspensions consist of 1-10 nm silver or gold particulates that are homogeneously suspended in an organic carrier. A piezo-electric droplet generator driven by a bipolar voltage signal is used to dispense 50-70 μm diameter droplets traveling at 1-3 m/s before impacting a compliant polyimide substrate. The deposit/substrate composite is subsequently processed at 300°C for 15 min to allow for complete evaporation of the carrier and for sintering of the nano-particles, thereby yielding a finished circuit interconnect. Test vehicles created using this technique exhibit features as fine as 120 μm wide and 1 μm thick with resistivities on the order of 3.5×10^-5 Ωcm. The circuitry performed well under environmental conditioning. As expected, repeatability of circuitry fabrication showed sensitivity to the generation of steady, satellite-free droplets. In an effort to generate droplets consistently, it is essential to develop a strong fundamental understanding of the correlation between device excitation parameters and dispensed fluid properties, and to resolve the microrheological behavior of the NPFS when flowing through the droplet generator     

Scrubbing Hydrogen Sulfide from Gases. A Rational Approach

Worsening of the environmental situation in many regions of Russia in recent decades is to a great degree due to production and refining of oil and gas with a high hydrogen sulfide content. Industrial methods of utilization of hydrogen sulfide are extremely irrational: it is either burned in flares or used for production of sulfur whose quality and quantity pose new problems related to its use.     

An investigation of the Co:MgF2laser system

The Co:MgF2laser, tunable over the range from 1.5 to 2.3 μm, has been investigated under a variety of operating conditions. Included in this paper are reports on basic spectroscopy of Co:MgF2, a determination of the gain cross section, the efficiency and temporal behavior under pulsed excitation, and performance in theQ-switched mode. In addition, operation with thermoelectric cooling and CW oscillation at the multiwatt power level are discussed. Equations covering laser-pumped lasers are derived and comparisons between experiments and theory are presented.