Data Acquisition for Automated Track Inspection

The purpose of this paper is to describe the use of a minicomputer in an integrated track inspection program. The basic elements of such a program include the measuring vehicle, data reduction process, and presentation of data to the various management levels. The paper describes such a system which has been in use on the Southern Railway for over five years and points out desirable changes, problems, and economics.     

SELENIUM BLACK GLASS*

A black glass was made by melting a soda-lime-silica glass under a reducing atmosphere with the addition of 0.6% of selenium and 0.1% of cobalt carbonate, CoCO_s. The light absorption of a specimen about 0.01 inch thick in the range of 400 to 750 mp was superior to that of commercial black glass. The maximum transmission was 27% at 750 mp. The use of nickel and iron oxides is less effective than cobalt oxide for obtaining selenium black glass.     

Investigations of the diurnal cycle and mixing state of oxalic acid in individual particles in Asian aerosol outflow

The mixing state of oxalic acid was measured in Asian outflow during ACE-Asia by direct shipboard measurements using an ATOFMS single-particle mass spectrometer. Oxalic and malonic acids were found to be predominantly internally mixed with mineral dust and aged sea salt particles. A persistent diurnal cycle of oxalic acid in mineral dust occurred for over 25 days in marine, polluted marine, and dust storm air masses. The preferential enrichment of diacids in mineral dust over carbonaceous particles and their diurnal behavior indicate a photochemical source of the diacids. Oxalate was only detected simultaneously with elevated aged dust particle counts. This suggests that the diurnal production of diacids most likely results from episodic atmospheric processing of the polluted dust aerosol. We propose a mechanism to explain these observations in which the photochemical oxidation of volatile organic compounds is followed by partitioning of the diacids and precursors to the alkaline Asian dust, with subsequent heterogeneous and aqueous oxidation. Our data indicate that the particulate diacids were produced over just a few hours close to the source; no significant production or destruction appears to have occurred during long-range transport to the ship. No evidence of extensive cloud processing of the sampled aerosol was found. This mixing state of diacids has important implications for the solubility and cloud nucleation properties of the dominant fraction of water-soluble organics and the bioavailability of iron in dust.     

Investigations of the influence of the laser texture design in the hard disk landing zone on the dynamic characteristics of Pico slider during contact take-off

 A good laser texture design in hard disk landing zone can significantly reduce the slider-disk contact force, contact time and contact frequency during a slider's contact start and stop process. In this paper a numerical investigation was conducted on the effects of laser texture properties, disk topography and slider design on the dynamic characteristics of a Pico slider during its take-off in the landing zone. Factors considered in this study are bump  height, bump diameter, bump density, slider crown, spin acceleration, and waviness. The slider contact take-off process was simulated with various values of those factors, and the results were analyzed through comparing the contact frequency, contact force, contact time, and take-off speed. The simulation results show that a regular take-off is not a continuous contact process, but composed of periodical contact bursts, and the time duration of each group of contact bursts is about the same. It has been found that some of the laser texture properties can significantly influence the slider's take-off characteristics. Properly choosing laser texture design parameters can reduce the impacts between slider and bumps during the take-off process. Received: 25 September 2001/Accepted: 7 May 2002     

Equipment replacement decisions and lean manufacturing

Traditional manufacturing systems are built on the principle of economies of scale. Here, the large fixed costs of production are depreciation-intensive because of huge capital investments made in high-volume operations. These fixed costs are spread over large production batch sizes in an effort to minimize the total unit costs of owning and operating the manufacturing system. As an alternative to “batch-and-queue,” high-volume, and inflexible operations, the principles of the Toyota Production System (TPS) and lean manufacturing have been widely adopted in recent years in the US [1, 2, 3 and 4]. In this paper, we illustrate an equipment replacement decision problem within the context of lean manufacturing implementation. In particular, we demonstrate how the value stream mapping (VSM) suite of tools can be used to map the current state of a production line and design a desired future state. Further, we provide a roadmap for how VSM can provide necessary information for analysis of equipment replacement decision problems encountered in lean manufacturing implementation.     

Reduced inorganic sulfur speciation in drain sediments from acid sulfate soil landscapes

We examined processes regulating reduced inorganic sulfur (RIS) speciation in drain sediments from coastal acid sulfate soil (ASS) landscapes. Pore water sulfide was undetectable or present at low levels (0.6-18.8 microM), consistent with FeS(s) precipitation in the presence of high concentrations of Fe2+ (generally >2 mM). Acid-volatile sulfide (AVS), with concentrations up to 1019 micromol g(-1), comprised a major proportion of RIS. The AVS to pyrite-S ratios were up to 2.6 in sediment profiles containing abundant reactive Fe (up to approximately 4000 micromol g(-1)). Such high AVS:pyrite-S ratios are indicative of inefficient conversion of FeS(s) to pyrite. This may be due to low pore water sulfide levels causing slow rates of pyrite formation via the polysulfide and H2S oxidation pathways. Overall, RIS speciation in ASS-associated drain sediments is unique and is largely regulated by abundant reactive Fe.     

Increasing the moisture content of imitation cheese: effects on texture, rheology and microstructure

Increasing moisture content may be a practical and cost-effective means to control the functional properties of imitation cheese. Imitation cheeses with moisture contents of 46, 50, 52 and 54 g/100 g were manufactured. An increase in the moisture content of the imitation cheese resulted in significantly increased meltability, tan values and decreased hardness (all P<0.05). The relationship between moisture content (x) and meltability (y) was described by the model (r²=0.99). A linear relationship emerged between moisture content (x) and hardness (y), where (r²=0.95) but cohesiveness was unaffected by moisture content. Increasing the moisture content to 52 or 54 g/100 g led to pockets of free water within the cheese and larger but fewer fat globules. The maximum level of moisture that the cheese matrix can retain appears to be 54 g/100 g.     

Vapor-Phase-Mediated Phenomena Associated with High Temperature,High Water Content Oxidation of MCrAlX Bond Coats

Oxidation of MCrAlX (M = Ni and Co; X = Y or Re) bond coats was carried out at 1,125 °C in a range of N₂–O₂–H₂O environments. A three-step process of (1) oxidation, (2) taper-polishing, and (3) re-oxidation was used to evaluate steady state development of thermally grown oxide (TGO). During initial oxidation, transient (Ni,Co)(Al,Cr)₂O₄ spinel formed above α-Al₂O₃. Following taper-polishing, no new spinel grew during 1–200 h of re-oxidation in any water vapor environment; spinel growth at the TGO surface by a steady state mechanism—owing to Al-depletion of the bond coat, as predicted elsewhere—was deemed unlikely. Observations of transient spinel volatilizing in wet environments were supported by measurements of nickel volatilizing from pre-fabricated NiAl₂O₄ spinel pellets as a function of humidity. In some cases, following volatilization, water promoted vapor phase-redeposition of spinel onto adjacent specimen surfaces. Spinel-related conclusions from past humid oxidation experiments for which volatilization phenomena were not considered—and especially for which Al-depletion of the bond coat is cited as the cause for spinel growth—should be reevaluated.     

Structural studies on an inhibitory antibody against Thermus aquaticus DNA polymerase suggest mode of inhibition

TP7, an antibody against Thermus aquaticus DNA polymerase I (TaqP), is usedas a thermolabile switch in 'hot start' variations of PCR to minimizenon-specific amplification events. Earlier studies have established thatTP7 binds to the polymerase domain of TaqP, competes with primer templatecomplex for binding and is a potent inhibitor of the polymerase activity ofTaqP. We report crystallographic determination of the structure of an Fabfragment of TP7 and computational docking of the structure with the knownthree-dimensional structure of the enzyme. Our observations stronglysuggest that the origin of inhibitory ability of TP7 is its binding toenzyme residues involved in DNA binding and polymerization mechanism.Although criteria unbiased by extant biochemical data have been used inidentification of a putative solution, the resulting complex offers aneminently plausible structural explanation of biochemical observations. Theresults presented are of general significance for interpretation of dockingexperiments and in design of small molecular inhibitors of TaqP, that arenot structurally similar to substrates, for use in PCR. Structural andfunctional similarities noted among DNA polymerases, and the fact thatseveral DNA polymerases are pharmacological targets, make discovery ofnon-substrate based inhibitors of additional importance.