3 research outputs found
REDUCING POWER DURING MANUFACTURING TEST USING DIFFERENT ARCHITECTURES
Power during manufacturing test can be several times higher than power consumption in functional mode. Excessive power during test can cause IR drop, over-heating, and early aging of the chips. In this dissertation, three different architectures have been introduced to reduce test power in general cases as well as in certain scenarios, including field test.
In the first architecture, scan chains are divided into several segments. Every segment needs a control bit to enable capture in a segment when new faults are detectable on that segment for that pattern. Otherwise, the segment should be disabled to reduce capture power. We group the control bits together into one or more control chains.
To address the extra pin(s) required to shift data into the control chain(s) and significant post processing in the first architecture, we explored a second architecture. The second architecture stitches the control bits into the chains they control as EECBs (embedded enable capture bits) in between the segments. This allows an ATPG software tool to automatically generate the appropriate EECB values for each pattern to maintain the fault coverage. This also works in the presence of an on-chip decompressor.
The last architecture focuses primarily on the self-test of a device in a 3D stacked IC when an existing FPGA in the stack can be programmed as a tester. We show that the energy expended during test is significantly less than would be required using low power patterns fed by an on-chip decompressor for the same very short scan chains
The application of seismic reflection surveying to the characterisation of aquifer geometry and related active tectonic deformation, North Canterbury
Groundwater resources critical to North Canterbury's agriculture, and industrial sustainability and development are predominately located within the Late Quaternary age (0- 0.78 myr)
sediments that underlie, and form the North Canterbury Plains.
The aim of this research is to determine if shallow seismic reflection P-wave surveying is
capable of delineating sedimentary architecture related to groundwater resources in the glaciofluvial
and fluvial sediments of the North Canterbury Plains and in particular, if (high
porosity/permeability pathways) and aquitard (low permeability) units can be differentiated
and so be applied to understanding groundwater resource in the North Canterbury region.
The research was undertaken in three geographic areas in North Canterbury, which represent
the main environments for Late Quaternary sedimentary deposition. i) The Omihi Valley a
thrust controlled foothill valley setting. ii) The Racecourse Hill-Burnt Hill area which
represents a basin-marginal setting close to the emergence of the glacial outwash fans that
constitutes the Northwest Canterbury composite aggradation surfaces, and iii) Pines Beach, a
more extensively reworked prograding postglacial braidplain with repeated episodes of
marine incursion.
Three methodologies have been developed to identifY aquifer units in the Late Quaternary
sediments of North Canterbury using shallow seismic reflection surveying.
1. Combined structural delineation seismic surveys and borehole logging to define
medium scale (lOrn- 2 km) structures and lithology which affect aquifer and aquitard
location and extents.
2. Tailored two and three dimensional shallow seismic reflection surveys to define
sedimentary architecture within the larger scale sediment packages delineating high
porosity/permeability pathways e.g. paleo-channels in the Omihi Valley and paleo-cut
and fill valleys on the Northwestern Canterbury Plains margin.
3. Changes in seismic reflection attributes which directly reflect sediment changes in
permeability and porosity such as the decrease in interval velocity with reduced matrix
clay/silt content in the Omihi Valley Late Quaternary sediments.
The main research outcome achieved from the 33 km2 Omihi Valley was the integration of
geological/geophysical mapping with lithological borehole logging to develop a groundwater
resource model allowing a predictive approach to its exploration and utilization. Structural
geometry and styles of deformation of the Valley have also been characterised .
The seismic reflection survey results for Burnt Hill and Racecourse Hill, both basin-margin
areas, indicate that seismic surveying can be successfully used to image alluvial and fluvial
architecture at scales from 10m- 1000's m, but with lower lateral ( ~28m@ 100m depth)
and vertical resolution ( 4 m) than that of the Omihi Valley surveys. The interpretation of the
intra-gravel seismic reflections is complex, and likely only to be possible with three
dimensional seismic reflection surveying.
In the third site, only a limited survey of one line was undertaken at Pines Beach (Canterbury
Plains/Pegasus Bay junction). This survey indicates that interfingering of reworked finergrained
fluvial sediments and coastal marine sediments can be successfully characterized with a lateral resolution of< 11 m and vertical resolution of 1.5 m for sediments within the top 50
m.
The research generally demonstrates that shallow seismic reflection P-wave surveying can be
extended to the more laterally extensive North Canterbury Plains as a whole, where it is
capable of delineating subsurface sedimentary facies, including hydrologically important
architecture, down to sub-two metre vertical resolution, in glacio-fluvial, fluvial and shallow
marine derived sediments in the 20 - 500 m depth range. The paleo-sedimentary structures
successfully delineated in the three field areas include paleo-channels, channel fill, large scale
erosional cut-and-fill valleys, floodplain surfaces, and alluvial fans.
It is shown that the aquifer and aquitard contrast in North Canterbury is not characterised by
porosity, but by permeability differences (which are also affected by porosity). Aquifers are
saturated high porosity/permeable sediments with low silt/clay content while aquitards are
saturated units with low permeability which appear (in the Omihi Valley) to be controlled by
silt/clay content, but not necessary low porosity.
P-wave seismic reflection surveying is shown to be insensitive to sediment permeability
variations, but limited data from the Omihi Valley indicates that seismic P-wave velocities
may be sensitive to matrix clay/silt content. If proven elsewhere in the Canterbury Plains
region, this may lead to a method of defining aquifer/aquitard geometry directly, without the
need to use indirect methods such as paleo-fluvial facies architecture delineation.
This thesis concludes that shallow seismic reflection surveying is capable of characterizing
the North Canterbury Plains and foothills valleys sedimentary lithofacies architecture, and
also shallow, tectonically-driven structural deformation, when used as part of a multi-faceted
programme of investigation. These data can be used to delineate the main groundwater
resources. Further research is required to determine if direct aquifer geometry identification is
possible by seismic P-wave interval velocity inversions and to increase seismic reflection
acquisition speed to allow efficient coverage of large areas
Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress
Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018