Overbreak and underbreak in underground openings Part 2: causes and implications   总被引：7，自引：0，他引：7  

J. A. Ibarra  N. H. Maerz  J. A. Franklin 《Geotechnical and Geological Engineering》1996,14(4):325-340

Summary The newly developed light sectioning method has been used to investigate some of the causes and costs of overbreak and underbreak. Investigations at the Aquamilpa Hydroelectric Project in Mexico have shown decreased overbreak and increased underbreak as a result of increased rock quality and decreased explosive energy. A new measure of explosive energy, the perimeter powder factor (PPF), has been defined and shown to be useful in the context of tunnel-wall rock damage. Tentative results indicate that explosive energy (PPF) may be a more important factor in producing underbreak, whereas rock quality may be a greater factor in producing overbreak. A site-specific equation is given for predicting overbreak or underbreak as a function of rock quality and explosive energy, with an evaluation of the cost of underbreak and overbreak.  相似文献   

Optimal placement of dampers and actuators based on stochastic approach     

Franklin Y. Cheng  Hongping Jiang  Xiaozhe Zhang Ph.D. Candidate 《地震工程与工程振动(英文版)》2002,1(2):237-249

A general method is developed for optimal application of dampers and actuators by installing them at optimal location on seismic-resistant structures. The study includes development of a statistical criterion, formulation of a general optimization problem and establishment of a solution procedure. Numerical analysis of the seismic response in time-history of controlled structures is used to verify the proposed method for optimal device application and to demonstrate the effectiveness of seismic response control with optimal device location. This study shows that the proposed method for the optimal device application is simple and general, and that the optimally applied dampers and actuators are very efficient for seismic response reduction.  相似文献   

The age of glacier peak tephra in west-central Montana     

Peter J. Mehringer  John C. Sheppard  Franklin F. Foit 《Quaternary Research》1984,21(1):36-41

At Sheep Mountain Bog, near Missoula, Montana, a late-glacial tephra, that probably fell in late summer, is preserved as an 8-mm-thick graded bed overlain by another 8 mm of redeposited ash mixed with lake deposits. Sediment surrounding the ash was ¹⁴C dated to about 11,200 yr B.P. Electron-microprobe analyses of the volcanic glass and hornblende phenocrysts from this ash layer indicate that they are similar in major-element chemistry to those of Glacier Peak layer G previously considered to be about 12,000 yr old or older.  相似文献   

Laboratory tests as a basis for the control of sewage sludge dumping at sea     

Frances L Franklin 《Marine pollution bulletin》1983,14(6):217-223

Toxicity and bioaccumulation studies were carried out on a number of UK sewage sludges to determine whether laboratory experiments could be used to regulate sludge dumping at sea. Whilst the acute toxicity of sewage sludges to adult marine organisms was generally low, shrimp larvae were found to be up to 500 times more sensitive than adults of the same species. No significant bioaccumulation of mercury or cadmium could be detected following up to 60 days exposure of fish, shrimps and mussels to the most heavily contaminated sludges available, although there was some uptake of lead, zinc and copper.  相似文献   

Secular resonance,solar spin down,and the orbit of Mercury     

William R. Ward  G. Colombo  F.A. Franklin 《Icarus》1976,28(4):441-452

A mechanism capable of accounting for the large mean eccentricity (0.175) and inclination (7°.2) of Mercury is discussed. Provided the gravitational field of the rapidly rotating primordial Sun had a sufficiently large second degree harmonic (i.e., J₂ ? order 10^?3), subsequent solar spin down would drive the orbit of Mercury through two secular resonances with Venus, one involving the precession of the line of apsides, the other one involving the regression of the nodal line. Resonance passage generates contributions to the eccentricity and inclination that are proportional to the square root of the characteristic solar spin down time. We find that an initial solar rotation l period of $\text{P ? 5}\text{1}\text{2}\text{hr}$ guarantees passage through resonance and that a spin down time of $\text{τ = Ω|dΩ/dt|}{}^{\mathrm{?1}}$ of order 10⁶ years could have produced the observed eccentricity and inclination. Such a primordial rotation rate is comparable to the measured rotations of very young stars and the spin down time appears consistent with the time scale derived for magnetic braking of the Sun's rotation by an intense solar wind during a T-Tauri stage of solar evolution.  相似文献   

Species distribution and diversity,habitat selection and connectivity: introduction to the Third Special Issue on Spatial Ecology     

Shawn William Laffan  Andrew K. Skidmore  Janet Franklin 《International journal of geographical information science》2014,28(8):1527-1530

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“Washed away”—assessing community perceptions of flooding and prevention strategies: a North Queensland example     

Richard C. Franklin  Jemma C. King  Peter J. Aitken  Peter A. Leggat 《Natural Hazards》2014,73(3):1977-1998

This article explored the perceptions of residents of a regional city in North Queensland of how to remain safe during flood events. It also explored reasons for and how to prevent risk-taking behaviour in floodwater using the protection motivation theory (PMT). PMT is a psychological theory which has recently been applied to assess behaviour during floods and was used as a framework to analyse the themes of responses to the online survey. The online survey was conducted prior to the wet season of 2011/2012 with 130 Townsville residents participating. The results indicate that about half of respondents (55 %) had some experience with floods of which driving through floodwater (38 %) was the most common type of flood experience listed and was more common amongst male respondents. Respondents’ advice to keep friends and family safe during floods was consistent with “coping appraisal”, which would improve their ability to cope with the flood. Prior experiences with floodwater influenced the reasons given for why people drive through floodwater and were taken to be indicative of an actor/observer bias. Respondents who had experience driving through floodwater (the actors) indicate how the context of the situation can influence decision-making, whereas those respondents who had no personal experience of driving through floodwater (the observers) were more likely to cite low perceived vulnerability of harm as a motivator. Prevention strategies focused on structural mechanisms to block access, information provision and punishment of offenders. It is suggested that in communities which regularly experience flooding, timely and context-specific reminders of the dangers inherent in floodwater along with the type, effectiveness and cost of protective action could minimise the public’s contact with floodwater and prove useful regardless of past experiences.  相似文献   

Subtidal response of the Scotian shelf bottom pressure field to meteorological forcing     

Franklin B. Schwing 《大气与海洋》2013,51(1):157-180

Abstract

Data collected during the Canadian Atlantic Storms Program (CASP) show subtidal variations in subsurface pressure (SSP) to be highly coherent throughout the Scotian Shelf region, and well correlated to fluctuations in the alongshelf component of wind stress (τ^y). Analysis using a frequency‐dependent multiple regression model verified that τ^y is the primary source of local forcing to the SSP field, although non‐locally generated variations in SSP are also important. The two components of local wind stress and a non‐local SSP term combine to explain over 90% of SSP variance on the Scotian Shelf.

Statistical results describing the response to τ^y change dramatically depending upon the inclusion of non‐local forcing. In a model including both types of forcing, the SSP response to local forcing behaves like the solution to a dynamical model forced by time‐dependent wind stress with sea‐level prescribed to zero at the eastern cross‐shelf boundary. Local τ^y forcing becomes more effective to the west and onshore, whereas the phase suggests propagation to the west. The importance of τ^y is reduced at higher frequencies. Describing SSP with a statistical model containing local forcing alone may lead to an incorrect interpretation of SSP dynamics, particularly in the synoptic band where the wind variance is greatest.

Energy originating from a non‐local source is most obvious at ω > 0.5 cpd and at locations on the eastern half of the shelf, but plays an important role at all sites and at all frequencies. These variations propagate to the west at speeds of 6.5 (ω < 0.2 cpd), 25–33 (0.2 cpd < ω < 0.5 cpd), and 12–17m s^?1 (ω > 0.5 cpd). The exponential decay scales at all frequencies are ～900 km in the direction of phase propagation. The non‐local response is consistent with theoretical estimates of first‐ and second‐mode shelf waves for this region and represents the most direct evidence of shelf wave activity on the Scotian Shelf to date.  相似文献   

Growing up and cleaning up: The environmental Kuznets curve redux   总被引：1，自引：0，他引：1  

Rachel S. Franklin  Matthias Ruth 《Applied geography (Sevenoaks, England)》2012,32(1):29-39

Borrowing from the Kuznets curve literature, researchers have coined the term “environmental Kuznets curve” or EKC to characterize the relationship between pollution levels and income: pollution levels will increase with income but some threshold of income will eventually be reached, beyond which pollution levels will decrease. The link between the original Kuznets curve, which posited a similar relationship between income and inequality, and its pollution-concerned offspring lies primarily with the shape of both curves (an upside-down U) and the central role played by income change. Although the EKC literature has burgeoned over the past several years, few concrete conclusions have been drawn, the main themes of the literature have remained constant, and no consensus has been reached regarding the existence of an environmental Kuznets curve. EKC research has used a variety of types of data and a range of geographical units to examine the effects of income levels on pollution. Changes in pollution levels might also be at least partly explained by countries’ position in the demographic transition and their general population structure, however little research has included this important aspect in the analysis. In addition, few analyses confine themselves to an evaluation for one country of the long-term relationship between income and pollution. Using United States CO₂ emissions as well as demographic, employment, trade and energy price data, this paper seeks to highlight the potential impact of population and economic structure in explaining the relationship between income and pollution levels.  相似文献   

Saturn's rings—A survey     

A.F. Cook  F.A. Franklin  F.D. Palluconi 《Icarus》1973,18(2):317-337

In this review paper we first discuss the dimensions of major ring features and of the disk of the planet. We then summarize the observed photometric parameters, and because frozen H₂O appears to be a major ring constituent, we compare the appropriate photometric properties of various forms of snow with those of the ring. We examine several ring models, noting certain characteristics that any model should supply. In our view, a physical means of accounting for the observed ring thickness of ～2 km is a prime requirement. There appears to be one model that presents no clear observational or theoretical inconsistency. Finally, we list certain problems whose solutions should broaden our knowledge of the ring system.  相似文献