Assessment of various code provisions based on optimum design of steel structures     

Franklin Y. Cheng  D. S. Juang 《地震工程与结构动力学》1988,16(1):45-61

This paper presents some comparative design results of typical structural systems in accordance with various code provisions, such as UBC and ATC-03 of the U.S. and TJ-11–78 of China. The solution comparisons are based on an optimization scheme for a given set of constraints and objective functions. Three levels of recursive procedures are employed in the algorithm to search for an optimum weight or construction cost including damages. Numerical examples are provided to compare the design results based on the aforementioned code provisions.  相似文献   

Thermoluminescence dating of tertiary period calcite     

A.D. Franklin  W.F. Hornyak  A.A. Tschirgi 《Quaternary Science Reviews》1988,7(3-4)

  相似文献   

Blast overbreak measurement by light sectioning     

John A. Franklin  Jose T. Ibarra  Norbert H. Maerz 《Geotechnical and Geological Engineering》1989,7(4):323-331

Summary In this new method for measuring the cross-section of tunnels and other excavations, the opening is outlined by a plane of light projected from a conical mirror. The image is recorded on videotape, enhanced, then measured by microcomputer. The measured profile is compared automatically with the specified profile to give values for overbreak and underbreak.Trials in Mexican tunnels and at an underground mine in Canada have evaluated the technique in relation to traditional mechanical, photographic, and surveying alternatives. Results indicate that the light sectioning method requires less than a minute per profile and no surveying skills. Costs are low, and the measurements are accurate to within a centimetre or two. Using the same photoanalysis technique and software, rock quality can be measured at the same time and place as overbreak, which helps the engineer to decide whether overbreak is caused by geological conditions or by deficiencies in blasting.  相似文献   

Fire and other disturbances of the forests in Mount Rainier National Park   总被引：1，自引：0，他引：1  

Miles A. Hemstrom  Jerry F. Franklin 《Quaternary Research》1982,18(1):32-51

The recent history of catastrophic disturbances in forests was reconstructed at Mount Rainier National Park. Basic data were ages of trees based on ring counts of early seral conifer species and maps of age-class boundaries from field work and aerial photographs. Maps illustrate age classes of the forests and show disturbances from fires, snow avalanches, and lahars (volcanic mudflows). Fires are by far the most important major disturbers, followed by snow avalanches and lahars. Fires over 250 ha in size are called fire events. Burns over 1000 ha, which may have been one fire or a series of fires within a short time, are called fire episodes. Important fire events or episodes occurred in the years 1230, 1303, 1403, 1503, 1628, 1688, 1703, 1803, 1825, 1856, 1858, 1872, 1886, 1894, 1930, and 1934 A.D. The largest fire episode was in 1230; it affected approximately 47% of the forests in the park. The majority of the forests are over 350 yr old, and several stands are over 1000 yr old. Stands 350 yr and 100 to 200 yr in age are the most extensive age classes in the park. Three fire frequency indices are compared. None describe fire frequency at Mount Rainier well. Natural fire rotation was estimated at about 434 yr. All but two episodes of major fires since 1300 A.D. correspond well with major droughts reconstructed for locations east of the Cascade Range crest. Impacts of humans on the disturbance regime may have increased the frequency of fire in the 1850–1900 period, followed by a decrease in frequency after 1900. Fuel build-up as a result of fire suppression should have no significant impact on fire frequency, since fires are relatively infrequent and fuels accumulate naturally.  相似文献   

Notes on the occurrence,distribution, and biology of elasmobranch fishes in the Indian River lagoon system,Florida     

Franklin F. Snelson 《Estuaries and Coasts》1981,4(2):110-120

Fifteen species of elasmobranchs, eight sharks and seven rays, have been recorded with reasonable certainty from the Indian River lagoon system on the central east coast of Florida. We collected four shark and six ray species during a three and one-half year study of the northern portion of the lagoon system. Five of these appear to be year-round residents, and the remainder utilize the area only at restricted times of the year or as a nursery ground. The most abundant resident species areDasyatis sayi, D. sabina, andCarcharhinus leucas. Pristis pectinata, once a common resident species, has been extirpated from the lagoons. The distribution of ocean inlets and salinity appear to be major factors affecting diversity and numbers of elasmobranchs in the Indian River system.  相似文献   

Overbreak and underbreak in underground openings Part 1: measurement using the light sectioning method and digital image processing     

N. H. Maerz  J. A. Ibarra  J. A. Franklin 《Geotechnical and Geological Engineering》1996,14(4):307-323

Summary Quick, simple, reliable, and inexpensive measurements of overbreak and underbreak are needed for proper evaluation of tunnelling by the drill and blast method. Problems causing rock damage can be identified and remedied while the work is still in progress. The measurements are also useful in identifying causes of overbreak and overbreak, and in helping to settle contractual disputes relating to payment for replacement concrete and secondary blasting of tights (zones of underbreak). A newly developed method to measure underbreak and overbreak is presented here. The light sectioning method (LSM) uses a radial sheet of light to define the tunnel profile. An image of the final tunnel profile is acquired and digitized, using digital image analysis. This profile is superimposed over the design profile, and from this zones of overbreak and underbreak are identified, quantified, and presented graphically.  相似文献   

Photometry of Saturn's satellites: The opposition effect of Iapetus at maximum light and the variability of Titan     

F.A. Franklin  A.F. Cook 《Icarus》1974,23(3):355-362

We present photometry, V and (B - V), of Iapetus at six western elongations (the phase of maximum brightness) that span a range in solar phase, α, from ≈6° to <0°.4, and we find that a substantial opposition effect, >0.12 mag (V), is present. We make a few cautious remarks about the possible relevance of the use of this result to interpret the phase curve of Saturn's ring. We also give a few measures of Rhea and Hyperion, at $\text{α ? 0.3°}$, and more of Titan, which indicate that the latter has been anomalously bright during much of 1973 and 1974, sometimes by nearly 0.1 mag (V).  相似文献   

Tidal torques on infrequently colliding particle disks in binary systems and the truncation of the asteroid belt     

F.A. Franklin  M. Lecar  D.N.C. Lin  J. Papaloizou 《Icarus》1980,42(2):271-280

We study numerically and analytically the conditions leading to the truncation, at the 2:1 resonance, of a disk of infrequently colliding particles surrounding the primary of a binary system. We focus on systems with small mass ratios, q, such as the Sun-Jupiter system with q = 10^?3. Previous studies showed that if collisions are frequent with respect to the orbital period, truncation 3nly occurs if the Reynolds number is greater than q^?2. This corresponds to particle eccentricity, e, less than of order q for a particle disk of optical depth unity. In thepresent case collisions are less frequent than $\text{q}{}^{\mathrm{<mtext>?2</mtext><mtext>3</mtext>}}$ orbital periods (the period of the forced eccentricity at the 2:1 resonance), and truncation occurs and (Kirkwood) gaps are produced only if e is less than some critical value which we estimate to be of order $\text{q}{}^{\mathrm{<mtext>5</mtext><mtext>9</mtext>}}$, or ～0.02 for the Sun-Jupiter case. We mention several means whereby the eccentricities may have been subsequently increased to their observed values.  相似文献   

On the original distribution of the asteriods. I.     

Myron Lecar  Fred A. Franklin 《Icarus》1973,20(4):422-436

The depletion of an initially uniform distribution of asteroids extending form Mars to Saturn, caused by the gravitational perturbations of Jupiter and Saturn, is calculated by numerical integration of the asteroid orbits. Almost all (about 85%) the asteroids between Jupiter and Saturn are ejected in the first 6000 years Most of the asteroids between the $\text{2}\text{3}$ Jupiter resonance (4.0 A.U.) and Jupiter are ejected in the first 2400 years with the exception of the stable librators (e.g., the Hilda group). Interior to the $\text{2}\text{3}$ resonance the depletion was small, and interior to the $\text{1}\text{2}$ resonance (3.3 A.U.) no asteroids were ejected in the first 2400 years.  相似文献   

Influence of improved performance monitoring on the consistency of a bottom trawl survey   总被引：1，自引：0，他引：1  

Zimmermann  Mark; Wilkins  Mark E; Weinberg  Kenneth L; Lauth  Robert R; Shaw  Franklin R 《ICES Journal of Marine Science》2003,60(4):818-826

  相似文献