3,333 research outputs found
Rapa Nui (Easter Island)’s Stone Worlds
No full textThis article explores the spatial, architectural and conceptual relationships between landscape places, stone quarrying, and stone moving and building during Rapa Nui’s statue-building period. These are central themes of the ‘Rapa Nui Landscapes of Construction Project’ and are discussed using aspects of the findings of our recent fieldwork. The different scales of expression, from the detail of the domestic sphere to the monumental working of quarries, are considered. It is suggested that the impressiveness of Rapa Nui’s stone architecture is its conceptual coherence at the small scale as much as at the large scale. </div
The influence of flow acceleration on stone stability
No full textThe stability of a bed of stones subject to a flow is often described in terms of a critical velocity or shear stress generated by the flow. These classical design methods like for example Shields, do not take the influence of flow acceleration into account. In experiments and practice, it appeared that when a flow is accelerated, stones start to move at a point where the so-called critical velocity is not reached yet. The movement of stones must have a second cause beside the velocity of flow. Only a little information is known on the influence of flow acceleration on stone stability of the bed. The objective of this thesis is to obtain more insight into the influence of acceleration of flow on the stability of stones. By carrying out experiments in a flume containing a local contraction, the stone stability in an accelerated flow is investigated. In the contraction the stability of two different stone sizes, subject to different velocity-acceleration combinations, is analysed. If the hypothesis is correct, than for some velocity-acceleration combinations movement occurs while for the same velocity combined with a lower acceleration no movement occurs. The shear stress occurring in the accelerated flow is determined using the shear velocity. According to the classical Shields method the shear velocity is responsible for the movement of the stones. Movement is detected for lower shear velocities then expected. According to the hypothesis this is a result of the extra generated force on the stones due to acceleration. After analysing the data it appeared that combinations of the same velocity and different accelerations showed differences in movement. The amount of movement goes up for an increase in acceleration combined with a constant or slightly decreasing velocity. This proves that there is a relation between the stability of the stones and a combination of the velocity and acceleration generated forces. The Morison equation is used to describe the relation between the forces acting on a stone. It combines the force generated by acceleration and the force generated by the peak velocities due to turbulence, as the sum of both forces. The extra force due to acceleration appeared to be of the same order as the force due to the velocity. Therefore, when looking at the stone stability in an accelerated flow, it is important to take the force generated by the acceleration into account. The resulting Morison force acting on a stone is proved to be responsible for the stability of the stones. Finally, a unique relation, valid for both stone diameters, between the force acting on the stone and the entrainment is found. This power relation consists of a dimensionless Morison-Shields parameter representing the force on a stone and a dimensionless entrainment parameter. The relation does not depend on stone size and is therefore expected to be universal in use.Civil Engineering and Geoscience
The legal rights and responsibilities of the public school principal in Virginia
No full textThe public school principal in Virginia is in a most vulnerable position. Not only must the principal enforce the policies and regulations of the local school board, state mandates, federal laws and regulations, but must also respond to a multitude of daily crises, any one of which could result in litigation.
The primary purposes of this study were to examine and report the current legal status of the public school principalship in Virginia; to analyze and clarify the law as it relates to the school principal's role as both employee and “employer;” and to project trends in the direction which the courts applicable to Virginia appear to be headed.
The courts have been very protective of one's constitutional rights, regardless of whether one is a principal, teacher, or student. Thus, principals should guard against violating the constitutional rights of persons under his charge. However, the courts are also sympathetic to the many problems facing schools and administrators, but do expect them to act in a reasonable and prudent manner.Ed. D
Stratigraphy and sedimentology, Cambrian Shady Dolomite, Virginia
No full textCambrian Shady Dolomite facies exposed northwest and southeast of Austinville, southwestern Virginia, apparently formed in a platform-to-basin setting. Northwest of Austinville, the Shady Dolomite (600 m thick) overlies the Lower Cambrian Erwin Formation and is overlain by the Middle Cambrian Rome Formation. Here the unit consists of ribbon-laminated carbonates (Patterson Member) overlain by massive dolomites and fenestral, cryptalgal carbonates (Austinville and Ivanhoe Members) which pass up into Rome Formation red mudcracked clastics and carbonates. Relict textures suggest that northwestern belts of the Shady Dolomite were deposited in an upward-shoaling sequence on the inner part of a carbonate platform.
The Shady Dolomite thickens southeast of Austinville where exposed (400 m thick) upper Shady Dolomite beds (partly equivalent to Rome Formation) contain calcareous algal bioherms, limeclast grain-stone, monomictic and polymictic carbonate breccia and black laminated limestone and shale. Algal bioherms, limeclast grain-stones and carbonate breccias of southeastern belts suggest seaward, outer platform environments; black laminated limestone and shale units containing local algal bioherms and breccias may indicate local off-platform "deeper water" deposits. Slopes on the carbonate platform margin were probably low (few degrees) as indicated by interlayering of shallow and deeper water lithologies recording considerable migration of facies bands. This southeasternmost facies of the Shady Dolomite exposed in the Valley and Ridge may give important clues as to the lithologic character of equivalent units in the Virginia Piedmont.Master of Scienc
Construction Minerals in the Baltimore-Washington Metropolitan Area: A Land Management Analysis
No full textThe patchwork of government influences that shape the protection and management of construction mineral resources--sand, gravel, and crushed stone--includes statutes, regulations, guidance documents, and court decisions at the federal, state, and local level. Across the Washington-Baltimore metropolitan area, both these influences and the experiences that the counties have had in managing construction mineral resources range widely. The principal objective in this study is to discuss the mechanisms that counties use to manage such resources; the level and source of concern that local residents have with respect to construction mineral extraction operations; officials' perceptions about trends in the supply and demand for mineral resources; and the level of interest in protecting mineral resources for future exploitation. The study rests principally on a review of federal, state, and local planning documents, two detailed case studies of counties active in construction mineral management, and structured telephone interviews of thirty-six local planning officials and state and federal agency staff.
Scrivere di pietra | Writing about stone
No full textIl lavoro è uno degli 8 capitoli, dei quali 5 dell’autore, risultato di un’attività di ricerca commissionata dal Consorzio Produttori Pietra Piasentina di Torreano (Ud), responsabile scientifico il prof. Mauro Bertagnin. In questo caso viene fornita una bibliografia ragionata, che si auspica esaustiva, sulla pietra piasentina, brecciola calcarea eocenica usata in tutta l’area del Friuli orientale, partendo dai primi studi geologici di fine ‘800 e arrivare ai contributi più recenti, di carattere tanto geologico-tecnico che storico-etnografico. | This work is one of eight chapters, including five by the author, resulting from research commissioned by the Consortium of Producers of Piasentina Stone in Torreano (Ud), directed by prof. Mauro Bertagnin. This chapter contains an annotated bibliography, meant to be exhaustive, on Piasentina stone, the Eocene breccia used throughout the area of eastern Friuli, beginning with the early geological studies of the late 1800s and concluding with the most recent contributions, be they of a geological or historical and ethnographic nature
A performance baseline for stone matrix asphalt.
No full textIn 2003, Virginia launched an expanded commitment to stone matrix asphalt (SMA). By the end of 2004, contracts that encompassed nearly 400,000 tons of SMA had been awarded and most of the material produced and placed. During this 2-year timeframe, more construction districts and contractors were engaged in the design, production, and placement of SMA than at any time in the history of the Virginia Department of Transportation (VDOT). Most were experiencing it for the first time. This report documents many aspects of the 2003/2004 SMA "implementation initiative." It summarizes and presents detailed information on costs and quantities, volumetric properties, compaction, permeability, aggregate quality, and initial functional character (ride and friction) for SMA pavements placed during the 2003 and 2004 seasons. SMA is a complex and expensive HMA material. Carefully documenting (or "baselining") today's experiences and understanding the consequences in terms of lifetime costing are important keys to the continued successful deployment of the best HMA technologies for Virginia. If the cost savings associated with SMA (as identified by the National Asphalt Pavement Association) continue and are applied to only the 14% of VDOT's annual program allotted to SMA in 2005, the fruits of this research can contribute to more than $14 million per year in savings
Filemone, fr. 102 K.–A. e la reviviscenza tragica di una metafora mitica
No full textThis paper argues that the mention of Niobe turned into a stone in Philemon fr.
102 K.–A. is not merely a reference to the myth, but an allusion of the famous Aeschylean
Niobe. After presenting and discussing the comic fragment, the author provides sections
about the popularity of the Niobe myth and the reasons why Aeschylus’ Niobe was so
significant already in antiquity, which was mainly owing to the dramatist’ s presentation of
Niobe as silent until an advanced point of the performance. Niobe’ s silence is not attested
in other literary or mythographical sources. Next the author discusses the rationalization
of Niobe’ s metamorphosis in the fragment by Philemon, pointing out that it focuses
precisely on the silence of the woman, while other versions by different authors refer to
different aspects (linguistic misunderstandings, immobility, insensibility). Lastly, a short
meta-linguistic survey of the association stone/silence shows that this was not the only
possible nor the most expected outcome in Greek
Stability of Column-Supported Embankments
No full textColumn-supported embankments have a great potential for application in the coastal regions of Virginia, where highway embankments are often constructed on soft ground. The columns can be driven piles, vibro-concrete columns, deep-mixing-method columns, stone columns, or other suitable types. Column-supported embankments are used to accelerate construction by eliminating consolidation times that are needed for preloading and surcharging operations associated with conventional prefabricated vertical drains. This study has resulted in a development of new numerical stress-strain analyses to evaluate the stability of embankments supported on columns installed by deep mixing method. Such analyses reflect the multiple realistic failure mechanisms that can occur when strong columns are installed in weak soil. Detailed recommendations for performing numerical analyses are presented. The findings are also expected to apply to vibro-concrete columns, because they, like deep-mixing-method columns, are strong in compression but weak in bending and tension. The study also recommends the use of reliability analyses in conjunction with the stability analysis. Reliability analyses are necessary, because deep-mixed materials can be highly variable and because typical variations in the strength of the surrounding clay can induce abrupt tensile failure in columns. Additional benefit of the reliability-based design is that it permits rational development of statistically-based specifications for constructing deep-mixed materials.Virginia Department of Transportation 7397
Tacit knowledge, learning and expertise in dry stone walling
No full textThis is a detailed study of learning in the context of dry stone walling. It examines
what happens in the learning situation. The aim of this work was:
'To understand the nature of expertise in dry stone walling, how it is understood
by those practising the craft, and how it is transmitted to others'.
The main research questions were, therefore:
What happens when dry stone wallers are learning their craft?
How do they acquire expertise in dry stone walling?
How is this learning communicated?
This process necessitated developing a way of engaging with the practitioners,
eliciting descriptive data about what they were doing, and why they were doing it,
through interviews (or conversations) with both individuals and groups, whilst
they practiced their skill. Twenty three wailers were interviewed as they worked,
building walls.
The material obtained was analysed under seven different themes:
'Knowing how'
The use of tacit knowledge or intuition
'Flow'
Constant decision making, reflection and learning from mistakes
Individual and subjective variations and experiences
The relevance of emotion
The use of 'rules of thumb' or maxims.
Learning walling does not fit simply into any of the seven themes. It is
contextualised, complex and individual. It demonstrates tacit knowledge and
intuition. It involves emotion, sometimes consciously, sometimes not. It involves
memory, problem solving, and learning from mistakes, and reflection. Maxims or
'rules of thumb' were a key element in the learning process at all stages. Linear
stages of learning were not evidenced. Deep understanding of the practice is
evidenced, and the wider learning and teaching implications are explored
- …
