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  • 1
    Electronic Resource
    Electronic Resource
    An intelligent specifications extraction interface for structural design (1990)
    Springer
    Engineering with computers 6 (1990), S. 153-165 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Many descriptions of the design process do not include the specifications as part of the process, but rather as an input to the design. Once the specifications are considered to be the input, the assumption is made that they are in a form that is suitable for the design process to proceed. The need for a design always starts with ill-defined objectives. The process by which this information is transformed into well-defined design objectives is called the design specification extraction process. An attempt to expose the underlying structure of the first step in the design process—the design specifications—is presented in this paper. The extraction of specifications is divided into four major tasks—diagnosis or information gathering, interpretation and assessment, classification and decomposition, and information patching. The conceptual framework for the design specification extraction and synthesis is implemented in the expert system program SEISD (specification extraction interface for structural design) developed in the LISP programming language. A few examples are presented to demonstrate the implementation strategies. These examples are drawn from the specific problem of a beam design.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01200313
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Propagation of ultrasonic Lamb waves in piezoelectric plates (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4113-4120 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The propagation of the lowest-order symmetric (S0) and antisymmetric (A0) Lamb wave modes in a piezoelectric plate is investigated both theoretically as well as experimentally. The characteristics of the modes and their relation to the surface acoustic wave is modified by electrical boundary conditions on the plate surfaces. It is found that when both surfaces are either metallized or unmetallized, the surface acoustic wave is obtained by a linear superposition of the A0 and S0 modes. On the other hand, if only one surface is metallized, then the surface acoustic wave is equivalent to just one of modes (either the A0 or S0 mode, depending on which surface is metallized). The beating phenomenon, whereby wave energy launched on one surface transfers periodically back and forth between opposite plate surfaces, is present when both surfaces are either metallized or unmetallized, but is absent if only one surface is metallized. Experimental measurements performed on Lamb wave devices fabricated on Y-cut, Z-propagating lithium niobate plates are found to be in good agreement with theoretical calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349133
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  • 3
    Electronic Resource
    Electronic Resource
    Excitation of ultrasonic Lamb waves in piezoelectric plates (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 8018-8024 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The excitation of ultrasonic Lamb waves by an interdigital transducer (IDT) deposited on a piezoelectric plate is analyzed using the Green's-function method. The amplitudes of the generated Lamb waves are obtained in terms of the charge density on transducer electrodes. An electrostatic analysis that neglects piezoelectric coupling is used to relate this charge density to the voltage applied across the IDT. This is then used to calculate the radiation conductance of the transducer. Experimentally measured characteristics of interdigital transducers deposited on 128° Y-X and Y-Z lithium niobate plates are found to be in fair agreement with theoretical calculations. The analysis can also be used to calculate the electromechanical coupling between the IDT and various Lamb-wave modes. It is found that when the plate is more than a few acoustic wavelengths thick, the lowest-order symmetric and antisymmetric Lamb modes are almost equally generated. The slight difference in the velocities of these modes gives rise to the beating effect, whereby energy launched by the IDT on one surface transfers periodically back and forth between the two surfaces as a sinusoidal function of the distance traveled. A 65-MHz Lamb-wave delay line fabricated on a 0.25-mm-thick Y-Z lithium niobate plate shows the beating effect, with a beat wavelength of 14.7 mm, in good agreement with theoretical calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347498
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  • 4
    Electronic Resource
    Electronic Resource
    Surface acoustic-wave device for measuring rate of gas flow (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 208-213 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The use of a surface acoustic wave (SAW) device for measuring rate of gas flow is described. A delay-line stabilized SAW oscillator is heated above the ambient by using a novel approach in which radio frequency (rf) energy is converted to heat via acoustic dissipation. This "self-heating'' arrangement eliminates the need for a separate heater and associated circuitry. Convective cooling caused by gas flow results in a change in the substrate temperature and thereby the oscillator frequency. The frequency of a 75-MHz oscillator fabricated on a 128° rotated Y-cut, X-propagating lithium niobate substrate is found to vary by more than 55 kHz for variation in flow rate from 0 to 500 cm3/min. A dual-oscillator configuration is implemented to provide temperature compensation and a convenient low-frequency output corresponding to flow rate. Adequate flow-sensing response is achieved with only modest (15 mW) oscillator loop power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142307
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of growth regulators on somatic embryogenesis, plantlet regeneration, and post-transplant survival of Echinochloa frumentacea (1992)
    Springer
    Plant cell reports 11 (1992), S. 368-371 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract After placement on Murashige and Skoog's basal medium supplemented with 3–5 mg/l 2,4-D, immature inflorescence expiants of Echinochloa frumentacea gave rise to three distinct types of callus: a) loosely arranged and soft; b) compact and translucent; c) compact, sticky and mucilaginous. Somatic embryo formation occurred in type ‘b’ callus in about 18–24 d. Callus types ‘a’ and ‘c’ did not produce somatic embryos. The highest percentage of cultures exhibiting somatic embryogenesis occurred on the medium containing 5 mg/l 2,4-D and 0.5 mg/l kinetin. Somatic embryos also formed directly on the inflorescence (without intervening callus formation) in about 15% of the expiants placed on this medium. The addition of paclobutrazol or uniconazole (0.25 or 1 mg/l) to the medium had no influence on the percentage of cultures exhibiting direct somatic embryogenesis, but paclobutrazol slightly increased the mean number of somatic embryos per culture. Many of the callus-derived somatic embryos germinated when subcultured on basal MS medium supplemented with kinetin. Addition of paclobutrazol or uniconazole to the culture medium at 0.25 or 1 mg/l decreased somatic embryo germination and shoot elongation but increased root length and leaf width. Both paclobutrazol and uniconazole increased survival of the plantlets following transplanting to soil. Increased post-transplant survival was accompanied by reduced water loss from plantlets produced on culture media containing triazoles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233368
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Controlled cell wall regeneration for efficient microinjections of Nicotiana tabacum var. Carlson protoplasts (1990)
    Springer
    Plant cell reports 9 (1990), S. 117-120 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nicotiana tabacum var. Carlson protoplast culture conditions were modified to contain a cell wall inhibitor, 2,6-dichlorobenzonitrile, in order to delay cell wall regeneration and to allow efficient nuclear and cytoplasmic microinjections. Under modified conditions, the protoplast preparations appeared healthier as compared to the control protoplasts and showed no resistance at all during microinjection. Furthermore, the duration of protoplast microinjection was extended for up to 3–4 days. In order to set up nuclear microinjections, the nuclei of these protoplasts were stained either before or after immobilization without any adverse effect on their mitotic activity. Successful cytoplasmic microinjections were demonstrated by injecting Alfalfa mosaic virus (AMV) RNA, which resulted in viral infection of 14% of the injected protoplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232084
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    A toxicological examination of whitefish (Coregonus clupeaformis) and northern pike (Esox lucius) exposed to uranium mine tailings (1990)
    Springer
    Archives of environmental contamination and toxicology 19 (1990), S. 578-582 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Operation of the Gunnar uranium mine, in northern Saskatchewan, Canada, from 1955 to 1964, resulted in the deposition of radioactive tailings in Langley Bay, a small bay connected to Lake Athabasca. Previous publications have described the contamination of the sediments, water, macrophytes and fish of this area. The present study compares the parasite infestations, blood hematocrit, histopathology and condition factor (K) of the Langley Bay whitefish and northern pike populations with these factors measured for control populations from Lake Athabasca. No significant differences could be found, in any of the physiological parameters measured, between the contaminated and control populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059078
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  • 8
    Electronic Resource
    Electronic Resource
    Lead-210 sedimentation in Lake Ontario (1992)
    Springer
    Environmental geology 19 (1992), S. 121-126 
    Details
    ISSN: 1432-0495
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The sedimentation rates and diffusive sediment mixing coefficients at several Lake Ontario locations have been derived from measurements of unsupported210Pb profiles in sediment cores. The values of mixing coefficients obtained in the present study are significantly lower than those obtained previously through an analysis of porosity profiles. The present estimates, however, are consistent with the rather well-preserved pollutant profiles at some of these locations. It is observed that the more realistic value of the mixing coefficient, obtained by inclusion of the sedimentation rate parameter, follows the sign opposite to that for the constant obtained by regression analysis of the porosity data. Further work is required to delineate this apparent relationship between two important physical characteristics of deposited sediments. Analysis of available suspended sediment data shows that Niagara River supplies about 1.8 million tonnes of sediment annually to Lake Ontario. This value is significantly lower than that (4.6 mt/yr) used previously in constructing sediment and pollutant budgets for Lake Ontario. From the presently derived sedimentation rate and suspended solid discharge estimates, an average value of 441 km2 (range 220-938 km2) is obtained for the minimum area of Lake Ontario over which the Niagara River-supplied fine sediment is deposited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01797440
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Spectrophotometric observations of UX arietis (1991)
    Springer
    Astrophysics and space science 183 (1991), S. 11-15 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spectrophotometric observations of the RS CVn binary UX Arietis have been presented. The comparison of the observed fluxes with model atmospheres indicates that during the four phases observed, the temperature does not vary significantly. However, brightness variation of 0 m .23 are thought to be due to change in the surface emitting regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00643014
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  • 10
    Electronic Resource
    Electronic Resource
    An insight into the expert-seisd: A knowledge based system for structural design (1992)
    Springer
    Engineering with computers 8 (1992), S. 151-161 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The research reported in this paper addresses the application of artificial intelligence towards the automation of the engineering design process, in particular the structural design process. The application involves the development of the knowledge based expert system (KBES). The resulting KBES, called Expert-Seisd, is developed in Common Lisp on IBM PS/II system. In this paper, examples demonstrating the implementation of various aspects of the Expert-Seisd as applied to structural design are presented. These include user interface, database, knowledge base, inference engine, and knowledge acquisition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01200366
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    Paper (German National Licenses)
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