Mouse Chromosome 3

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46995/1/335_2004_Article_BF00648421.pd

Virtual construction of architecture using 3D CAD and simulation

3D modelling and computer simulations provide new ways for architecture students to study the relationship between the design and construction of buildings. Digital media help to integrate and expand the content of courses in drafting, construction and design. This paper describes computer-based exercises that intensify the student's experience of construction in several courses from sophomore to senior level. The courses integrate content from drafting and design communication, construction, CAD, and design. Several techniques are used to strengthen students'awareness and ability in construction. These include: Virtual design-build projects in which students construct 3D CAD models that include all elements that are used in construction. Virtual office in which several students must collaborate under the supervision of a student acting as project architect to create a 3D CAD model and design development documents. Virtual sub-contracting in which each student builds a trade specific 3D CAD model of a building and all of the trade specific models must be combined into a single model. Construction simulations (4D CAD) in which students build 3D CAD models showing all components and then animate them to illustrate the assembly process. Cost estimating using spreadsheets. These techniques are applied and reapplied at several points in the curriculum in both technical laboratory courses and design studios. This paper compares virtual construction methods to physical design-build projects and provides our pedagogical arguments for the use of digital media for understanding construction.

An experimental investigation of sand�mud suspension settling behaviour: implications for bimodal mud contents of submarine flow deposits

The settling behaviour of particulate suspensions and their deposits has been documented using a series of settling tube experiments. Suspensions comprised saline solution and noncohesive glass-ballotini sand of particle size 35·5 ?m &lt; d &lt; 250 ?m and volume fractions, ?s, up to 0·6 and cohesive kaolinite clay of particle size d &lt; 35·5 ?m and volume fractions, ?m, up to 0·15. Five texturally distinct deposits were found, associated with different settling regimes: (I) clean, graded sand beds produced by incremental deposition under unhindered or hindered settling conditions; (II) partially graded, clean sand beds with an ungraded base and a graded top, produced by incremental deposition under hindered settling conditions; (III) graded muddy sands produced by compaction with significant particle sorting by elutriation; (IV) ungraded clean sand produced by compaction and (V) ungraded muddy sand produced by compaction. A transition from particle size segregation (regime I) to suppressed size segregation (regime II or III) to virtually no size segregation (IV or V) occurred as sediment concentration was increased. In noncohesive particulate suspensions, segregation was initially suppressed at ?s ? 0·2 and entirely inhibited at ?s ? 0·6. In noncohesive and cohesive mixtures with low sand concentrations (?s &lt; 0·2), particle segregation was initially suppressed at ?m ? 0·07 and entirely suppressed at ?m ? 0·13. The experimental results have a number of implications for the depositional dynamics of submarine sediment gravity flows and other particulate flows that carry sand and mud; because the influence of moving flow is ignored in these experiments, the results will only be applicable to flows in which settling processes, in the depositional boundary, dominate over shear-flow processes, as might be the case for rapidly decelerating currents with high suspended load fallout rates. The 'abrupt' change in settling regimes between regime I and V, over a relatively small change in mud concentration (&lt;5% by volume), favours the development of either mud-poor, graded sandy deposits or mud-rich, ungraded sandy deposits. This may explain the bimodality in sediment texture (clean 'turbidite' or muddy 'debrite' sand or sandstone) found in some turbidite systems. Furthermore, it supports the notion that distal 'linked' debrites could form because of a relatively small increase in the mud concentration of turbidity currents, perhaps associated with erosion of a muddy sea floor. Ungraded, clean sand deposits were formed by noncohesive suspensions with concentrations 0·2 ? ?s ? 0·4. Hydrodynamic sorting is interpreted as being suppressed in this case by relatively high bed aggradation rates which could also occur in association with sustained, stratified turbidity currents or noncohesive debris flows with relatively high near-bed sediment concentrations.<br/