Relational mountain (density) clustering method and web log analysis

The mountain clustering method and the subtractive clustering method are useful methods for finding cluster centers based on local density in object data. These methods have been extended to shell clustering. In this article, we propose a relational mountain clustering method (RMCM), which produces a set of (proto) typical objects as well as a crisp partition of the objects generating the relation, using a new concept that we call relational density. We exemplify RMCM by clustering several relational data sets that come from object data. Finally, RMCM is applied to web log analysis, where it produces useful user profiles from web log data. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 375–392, 2005.     

Snakes on the watershed

We present a new approach for object boundary extraction, called the watersnake. It is a two-step snake algorithm whose energy functional is minimized by the dynamic programming method. It is more robust to local minima because it finds the solution by searching the entire energy space. To reduce the complexity of the minimization process, the watershed transformation and a coarse-to-fine strategy are used. The new technique is compared to standard methods for accuracy in synthetic data and is applied to segmentation of white blood cells in bone marrow images     

High-temperature superconducting microwave devices: Fundamental issues in materials, physics, and engineering

High-T _c superconductivity has generated a great deal of interest because of the challenges it presents in the fields of material science, condensed matter physics, and electrical engineering, and because of the potential applications which may result from these research efforts. Thin-film passive microwave components may become the first high-temperature superconducting (HTS) devices available for widespread use and commercialization. In this article, we review aspects of material science, physics, and engineering which directly impact high-T _c superconducting microwave devices and discuss issues which determine the performance of these devices. Methods of growing HTS thin films on large-area substrates, techniques for fabricating single-level HTS passive microwave components, and the relevant properties of high-T _c superconducting films are discussed, with a focus on thin films of the HTS material YBa₂Cu₃O_7–. Several known mechanisms for microwave loss in both the superconductor and the dielectric substrate are presented. An overview of the general classes of superconducting passive microwave devices is given, and representative microwave devices which have been recently demonstrated are described in detail. Examples of a select few HTS active microwave components are also presented. Potential microwave applications are illustrated with comparisons to current technology.     

Thermodynamics of iron-aluminum alloys at 1573 K

The activities of iron (Fe) and aluminum (Al) were measured in Fe-Al alloys at 1573 K using the ion-current-ratio technique in a high-temperature Knudsen cell mass spectrometer. The Fe-Al solutions exhibited negative deviations from ideality over the entire composition range. The activity coefficientsγ _Fe, andγ _A1 are given by the following equations as a function of mole fraction (x _Fe,x _Al): 1 $$\begin{gathered} 0< \chi _{A1}< 0.4 \hfill \\ ln \gamma _{Fe} = - 4.511 ( \pm 0.008)\chi _{A1}^2 \hfill \\ ln \gamma _{A1} = - 4.462 ( \pm 0.029)\chi _{Fe}^2 + 0.325( \pm 0.013) \hfill \\ 0.6< \chi _{A1}< 1.0 \hfill \\ ln \gamma _{Fe} = - 4.065 ( \pm 0.006)\chi _{A1}^2 + 0.099( \pm 0.003) \hfill \\ ln \gamma _{A1} = - 4.092 ( \pm 0.026)\chi _{Fe}^2 + 0.002( \pm 0.001) \hfill \\ \end{gathered} $$ The results showed good agreement with those obtained from previous investigations at other temperatures by extrapolation of the activity data to 1573 K.     

The supercooling dependence of the initial fold length of polyethylene crystallized from the melt: unification of melt and solution crystallization

Following the previous recognition [1], reached with the aid of real time low angle X-ray diffraction (using a synchrotron X-ray source) that in melt crystallized polyethylene the initial (primary) lamellar thickness is much smaller than hitherto envisaged, we have proceeded to construct the full relationship between primary fold length (I _g ^*) and supercooling (T) covering a wide range of crystallization temperature (T _c). The principal result of this work is the identification of supercooling as the sole factor which determinesI _g ^*. Comparison with crystallization from solution [2–4] has revealed that theI _g ^* against T curves are completely superposable thus removing the gap which has existed up to the present between melt and solution crystallization, bringing about a welcome unification of these two separate (at least as far as fold length was concerned) aspects of polymer crystallization. Further, we show that while T determinesI _g ^*, subsequent thickening is determined by the absolute temperature. Isothermal thickening in particular proceeds first by a large discontinuous step followed by a continuous logarithmic increase with time. The importance of these findings and in particular the affirmation of the unique role of supercooling for chain folding and lamellar crystallization in general is emphasized.     

High-temperature crystallization behaviour of amorphous Fe80B20

Samples of 0.003 in. round Fe₈₀B₂₀ amorphous wires were annealed in vacuo for 1 sec to 8 h periods at 780° C and the crystallinity induced in these wires from this heat treatment was studied through X-ray diffraction and field-ion microscopy. X-ray diffraction studies indicate that complete crystallinity is produced following 1 sec anneal at 780° C. However, the initial product is a primitive-tetragonal Fe₃B phase unlike the body-centred tetragonal Fe₃B observed in low-temperature isothermal transformation studies with this alloy. The Fe₃B phase is seen to persist in the diffraction patterns for annealing durations of up to 15 min. Upon annealing for periods of up to 1 h, an intermediate three-phase structure consisting of -Fe, Fe₃B, and Fe₂B is seen to result with a gradual decrease in the Fe₃B phase corresponding to longer annealing durations. Anneals of more than 1 h at 780° C are seen to result in the disappearance of the Fe₃B phase producing a two-phase microstructure consisting of -Fe(b c c) and Fe₂B (b c t). Field-ion-microscopy with a pure neon imaging gas at 78 K likewise indicates that existence of a three-stage phase structural change during the isothermal anneals, and the atomic arrangement of the various species are quite readily discernible because of the different symmetries contained in the three distinct phases.     

Annealing behaviour of amorphous Fe80B20 on continuous heating

Resistance measurements during direct heating of Fe₈₀B₂₀ amorphous alloys indicate phase changes occur at 395, 500, 720 and 840° C. Samples heated to these temperatures, and maintained for five minutes in a neutral atmosphere, show that a hardness maximum occurs at the crystallization temperature of 395° C and that annealing at 500° C produces a material with the same hardness. Above 500° C the microhardness is seen to drop below that of the amorphous alloy. Saturation magnetization measurements show a steady increase following each anneal, up to a temperature of 720° C, and the rate of increase is seen to drop in the range of 720 to 840° C. X-ray diffraction studies show that only a small fraction of the matrix is crystallized following the anneal at 395° C and the transformed phases are -Fe and Fe₃B. Following annealing at 500° C, an increased proportion of -Fe and Fe₃B are observed with complete crystallinity while samples heattreated at 720° C are seen to consist of a three-phase mixture of -Fe, Fe₂₃B₆ and Fe₂B. Annealing at 840° C is seen to produce an equilibrium phase mixture of -Fe and Fe₂B phases. Only in the sample annealed at 395° C is a fraction of the amorphous phase seen to persist, indicating that a 5 min anneal is not sufficient, at this temperature, to induce complete crystallization. These structural features are corroborated by field ion microscope analyses, made at liquid nitrogen temperature in a medium of pure neon, and scanning electron microscopy, and are also consistent with our earlier study involving the isothermal annealing, for various times, of Fe₈₀B₂₀ alloy at 780° C.     

AH-64D main transmission accessory drive spur gear installation fault detections

The US Army has launched an aggressive program to implement condition based maintenance on its rotary wing assets. Condition Based Maintenance takes advantage of technology developments in the areas of machinery monitoring, signal processing and fault modeling to reduce the cost of ownership through improved maintenance procedures. Documenting the reduction in maintenance burden, cost savings and increased safety through early detection of helicopter faults is an important step in justifying the program. This paper describes a novel technique used to detect a serious fault in the accessory section of the AH-64D Apache main transmission. The technique determines if the primary or secondary clutch system is driving the aircraft accessories through a tachometer speed ratio. The method has identified three aircraft operating on the secondary system allowing Army maintenance crews to replace the affected transmissions and quickly restore the aircraft to operational status.     

Office task effects on comfort and body dynamics in five dynamic office chairs

In the present study, we investigated the effect of office tasks on posture and movements in field settings, and the comfort rating for chair characteristics and correlation with type of task. The tasks studied were: computer work, telephoning, desk work and conversation. Postures, movements, chair part inclinations and comfort rating data were collected from 12 subjects. Computer work showed the lowest physical activity, together with upright trunk and head position and low backrest inclination. Conversation shows the highest activity of head legs and low back together with the highest cervical spine extension. In contrast, desk work provoked the most cervical spine flexion and showed the second lowest activity. The telephoning tasks showed medium activity and the highest kyphosis. Conversation showed the highest backrest inclination. Positive comfort relations were found for computer work and a "swing system" chair, for telephoning and an active longitudinal seat rotation, and for desk work and a chair with a three-dimensionally moveable seat.     

Human C-peptide. Part I: Radioimmunoassay

Synthetic human C-peptide bearing a Tyrosine group at its amino end is labelled with 125iodine using chloramin T or hydrogen peroxide and lactoperoxidase. The results are compared applying both methods. Antiserum to synthetic human C-peptide (without Tyrosine) which was partially compared to rabbit albumin, is raised in guinea pigs and goats. Goats show to be superior to guinea pigs concerning antibody production. The so-called "hook effect" phenomenon is observed in setting up the standard curves for the radioimmunoassay. Monotonically decreasing standard curves are obtained on dilution of antiserum with a high antibody titer which was produced by repeated immunization in goats. Free C-peptide and C-peptide bound to antiserum are separated with the anxion exchange resin Amberlite. Using this separation technique we excluded unspecific binding of labelled C-peptide to protein fractions in serum of diabetics. The sensitivity of our radioimmunoassay is approx. 0.3 ng C-peptide/ml serum. Intra- and interassay variability are below 10%. Human proinsulin is the only substance found to crossreact with the antiserum.