Author Keywords: power series; curve; surface; intersection problems; curve tracing; geometric continuity 相似文献
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61.
Joan M Ryder Monica Z Weiland Michael A Szczepkowski Wayne W Zachary 《International Journal of Industrial Ergonomics》1998,22(6):261-429
Many cognitive engineering methodologies for user-centered design involve modeling procedural knowledge; others deal with domain semantics or conceptual models. COGnitive NEwork of Tasks (COGNET) is a framework for modeling human cognition and decision-making which provides an integrated representation of the knowledge, behavioral actions, strategies and problem solving skills used in a domain or task situation, yielding a powerful cognitive engineering tool. A case study of the design of the user interface for a new telephone operator workstation is presented to illustrate the derivation of the design from the components of the COGNET model. The model does not directly convey any specific feature of the interface design, but rather a formal representation of what the user must do with the resulting interface. This information is then evolved through a set of transformations which systematically move toward design features, in a fully traceable manner.
Relevance to industry
With the increasing prevalence of technical systems in complex work domains, cognitive engineering is necessary in designing the user interface for those systems to promote efficient integration of person and machine. The cognitive engineering methodology presented here addresses that need. 相似文献
62.
Results from wear studies in repetitive impact sliding are described in this paper. The material pair studied consisted of steel CPM-10V (specimen) (where CPM denotes crucible particle metallurgy) and 17-4 precipitationhardened (PH) steel (counterface) with transverse sliding velocities of 4 and 8 m s?1. By means of scanning electron microscopy, energy-dispersive analysis of X-rays and X-ray diffraction methods it is shown that the wear is due to a material transport of the counterface 17-4 PH steel to the CPM-10V surface. In the wear process, a change in microhardness of the counterface substrate is apparent, and X-ray diffraction of debris confirms the presence of transformed metal. These products include γ-Fe together with trace amounts of α-Fe2O3; however, virtually no carbide from the CPM-10V steel was detected. 相似文献
63.
J Wayne H Suh Z Misulovin KA Sokol K Inaba MC Nussenzweig 《Canadian Metallurgical Quarterly》1994,1(2):95-107
Effects of etoposide (VP-16) and cytosine arabinoside (Ara-C) on the cell cycle of HL-60 and THP-1 cells were studied by flow cytometry using the bromodeoxyuridine (BrdU)/DNA assay technique to investigate the efficacy of VP-16 for monocytic leukemia cells. VP-16 inhibited the proliferation of THP-1 cells more strongly than that of HL-60 cells at any concentrations used at 24 and 48 hr. VP-16 arrested HL-60 and THP-1 cells in the G2/M phase and reduced them in the G0/G1 and early S phase at higher concentrations. There was no significant difference in the percentage of G2/M phase cells at the same concentration between both cells. However, reduction in the G0/G1 and early S phase cells was more marked in THP-1 than HL-60 cells significantly. On the other hand, Ara-C perturbed the cell cycle of HL-60 cells more than that of THP-1 cells at 24 and 48 hr. These results suggest that the effects of VP-16 on the cell cycle may be more intense in THP-1 than HL-60 cells, and support the efficacy of VP-16 for treating monocytic leukemia in vivo. 相似文献
64.
Scott R Boss Laurie J Kirsch Ingo Angermeier Raymond A Shingler R Wayne Boss 《欧洲信息系统杂志》2009,18(2):151-164
Information security has become increasingly important to organizations. Despite the prevalence of technical security measures, individual employees remain the key link – and frequently the weakest link – in corporate defenses. When individuals choose to disregard security policies and procedures, the organization is at risk. How, then, can organizations motivate their employees to follow security guidelines? Using an organizational control lens, we build a model to explain individual information security precaution-taking behavior. Specific hypotheses are developed and tested using a field survey. We examine elements of control and introduce the concept of ‘mandatoriness,’ which we define as the degree to which individuals perceive that compliance with existing security policies and procedures is compulsory or expected by organizational management. We find that the acts of specifying policies and evaluating behaviors are effective in convincing individuals that security policies are mandatory. The perception of mandatoriness is effective in motivating individuals to take security precautions, thus if individuals believe that management watches, they will comply. 相似文献
65.
Applications of power series in computational geometry 总被引:2,自引:0,他引:2
A number of algorithms are presented for obtaining power series expansions of curves and surfaces at a point. Some results on the radius of convergence are given. Two applications of series are given:
1. • for curve tracing algorithms, where a truncated series is used to approximate the curve of intersection of two surfaces
2. • to define nth degree geometric continuity, for arbitrary
66.
Bari ML Ukuku DO Kawasaki T Inatsu Y Isshiki K Kawamoto S 《Journal of food protection》2005,68(7):1381-1387
The inability of chlorine to completely inactivate human bacterial pathogens on whole and fresh-cut produce suggests a need for other antimicrobial washing treatments. Nisin (50 microg/ml) and pediocin (100 AU/ml) individually or in combination with sodium lactate (2%), potassium sorbate (0.02%), phytic acid (0.02%), and citric acid (10 mM) were tested as possible sanitizer treatments for reducing the population of Listeria monocytogenes on cabbage, broccoli, and mung bean sprouts. Cabbage, broccoli, and mung bean sprouts were inoculated with a five-strain cocktail of L. monocytogenes at 4.61, 4.34, and 4.67 log CFU/g, respectively. Inoculated produce was left at room temperature (25 degrees C) for up to 4 h before antimicrobial treatment. Washing treatments were applied to inoculated produce for 1 min, and surviving bacterial populations were determined. When tested alone, all compounds resulted in 2.20- to 4.35-log reductions of L. monocytogenes on mung bean, cabbage, and broccoli, respectively. The combination treatments nisin-phytic acid and nisin-pediocin-phytic acid caused significant (P < 0.05) reductions of L. monocytogenes on cabbage and broccoli but not on mung bean sprouts. Pediocin treatment alone or in combination with any of the organic acid tested was more effective in reducing L. monocytogenes populations than the nisin treatment alone. Although none of the combination treatments completely eliminated the pathogen on the produce, the results suggest that some of the treatments evaluated in this study can be used to improve the microbial safety of fresh-cut cabbage, broccoli, and mung bean sprouts. 相似文献
67.
Wei Hu Robert B. Clark Wayne R. Giles Colleen Kondo Henggui Zhang 《International journal of molecular sciences》2022,23(8)
A number of distinct electrophysiological mechanisms that modulate the myogenic spontaneous pacemaker activity in the sinoatrial node (SAN) of the mammalian heart have been investigated extensively. There is agreement that several (3 or 4) different transmembrane ionic current changes (referred to as the voltage clock) are involved; and that the resulting net current interacts with direct and indirect effects of changes in intracellular Ca2+ (the calcium clock). However, significant uncertainties, and important knowledge gaps, remain concerning the functional roles in SAN spontaneous pacing of many of the individual ion channel- or exchanger-mediated transmembrane current changes. We report results from patch clamp studies and mathematical modeling of the hyperpolarization-activated current, If, in the generation/modulation of the diastolic depolarization, or pacemaker potential, produced by individual myocytes that were enzymatically isolated from the adult mouse sinoatrial node (SAN). Amphotericin-mediated patch microelectrode recordings at 35 °C were made under control conditions and in the presence of 5 or 10 nM isoproterenol (ISO). These sets of results were complemented and integrated with mathematical modeling of the current changes that take place in the range of membrane potentials (−70 to −50 mV), which corresponds to the ‘pacemaker depolarization’ in the adult mouse SAN. Our results reveal a very small, but functionally important, approximately steady-state or time-independent current generated by residual activation of If channels that are expressed in these pacemaker myocytes. Recordings of the pacemaker depolarization and action potential, combined with measurements of changes in If, and the well-known increases in the L-type Ca2+ current, ICaL, demonstrated that ICaL activation, is essential for myogenic pacing. Moreover, after being enhanced (approximately 3-fold) by 5 or 10 nM ISO, ICaL contributes significantly to the positive chronotropic effect. Our mathematical model has been developed in an attempt to better understand the underlying mechanisms for the pacemaker depolarization and action potential in adult mouse SAN myocytes. After being updated with our new experimental data describing If, our simulations reveal a novel functional component of If in adult mouse SAN. Computational work carried out with this model also confirms that in the presence of ISO the residual activation of If and opening of ICaL channels combine to generate a net current change during the slow diastolic depolarization phase that is essential for the observed accelerated pacemaking rate of these SAN myocytes. 相似文献
68.
Peter Lloyd Woodfield Andrew Seagar Wayne Hall 《International Journal of Thermophysics》2012,33(2):259-278
Vibrating wire viscometers rely on the principle that the viscosity of the fluid surrounding the wire provides the dominant
damping action on the motion of the wire. However, some residual damping is always present due to other effects such as internal
friction of the wire (anelastic relaxation), losses through the wire supports, and magnetic damping. Magnetic damping is a
physical mechanism that has received relatively less attention than internal friction in the context of viscometers. The phenomenon
arises because the current induced by the motion of the wire contributes to the magnetic field in such a way as to oppose
its own motion. For a test circuit using a 40 μm diameter tungsten wire in a 0.3 T magnetic field, surprisingly, the effect
of magnetic damping was found to be of a similar order of magnitude to other non-viscous damping effects. The effect can be
accounted for by including the internal impedance of the oscillating voltage source in the model and it disappears completely
for a perfect oscillating current source. 相似文献
69.
70.
The method of the calculus of variations and the maximum principle are preposed for the design of 'LQR' controllers with the worst case disturbance rejection for a linear time-varying (LTV) plant on finite horizon. The disturbance is bounded by either the windowed L 相似文献