513 research outputs found
Old Concrete Makes Way for New Asphalt
Back in the middle seventies, the latest civil pavement engineering techniques and technology transformed the old single carriageway trunk road which linked the Western Cape towns of Cape Town and Somerset West together as well as connecting them to the eastern part of the country. This transformation changed this road into a modern dual carriageway facility. This new facility was constructed with the then latest technology involving slip form paved concrete. All went well until a new phenomenon involving the interaction of sodium monoxide in cement and the alkali minerals in the local crushed rock caused the concrete to expand and evidenced severe failure.
Although this early failure was kept in check for over 40 years, the section of this road which forms part of the transport hub at Cape Town International Airport, has finally been reconstructed giving way to a highly modified bituminous binder based pavement. The new pavement consists of an asphalt base, surfacing and friction course all produced with modified bituminous binders. The supporting layers have been constructed by recovering and crushing the old concrete and combining with further cement to form the stabilised supporting layers. This is regarded as a fully green approach to salvaging old problematic pavement materials.
With minimal effort and modification sound subbase layers have been created to provide the necessary support to the construction of modern asphalt layers to produce a more flexible pavement alternative for safe travelling on this busy route.Papers presented at the 38th International Southern African Transport Conference on "Disruptive transport technologies - is South and Southern Africa ready?" held at CSIR International Convention Centre, Pretoria, South Africa on 8th to 11th July 2019
Enhancing Performance and Energy Consumption of HER Caches by Adding Associativity
The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-54420-0_45Unlike other previous techniques, the recently proposed Hard Error
Recovery (HER) fault-tolerant cache provides 100% fault-coverage in L1 data
caches. This full coverage makes the HER cache appropiate for fault-dominated
future technology nodes.
An n-way set-associative HER cache implements one cache way with fast
SRAM banks and the remaining ways with eDRAM banks to address power and
area. Since the number of eDRAM cache blocks used in a specific HER cache
organization depends on the cache associativity (i.e., the implemented number of
ways), we expect that the performance and energy consumption provided by a
given HER cache design strongly depends on the cache geometry.
In this work we study the behavior of the HER cache design when applied to
a highly associative L1 cache like those found in some modern microprocessors.
In particular this work explores a 32KB 8-way associative L1 data cache such as
the one used in Intel Haswell microarchitecture.
Experimental results show that, at low-power modes compared to a conventional
cache with the same storage capacity and number of ways, area, leakage
power, and dynamic energy savings of a 4-way HER cache are by 25%, 85%,
and 62%, respectively. These percentages are further improved (by 40%, 89%,
and 68%, respectively) when the cache associativity is increased to 8 ways, while
the performance loss with respect to both an 8-way conventional cache and the
4-way HER cache is minimal.This work was supponed by Generalitat de Catalunya (200950R1250), by FP7 program of the European Commission (TRAMS-248789), by Spanish Ministerio de Economía y Competitividad (MINECO) and by FEDER funds
under Grant TlN2012-38341-C04-01 and TIN2010-18368.Lorente Garcés, VJ.; Valero Bresó, A.; Canal, R. (2014). Enhancing Performance and Energy Consumption of HER Caches by Adding Associativity. En Euro-Par 2013: Parallel Processing Workshops. Springer. 454-464. https://doi.org/10.1007/978-3-642-54420-0_45S454464Bhavnagarwala, A.J., et al.: The Impact of Intrinsic Device Fluctuations on CMOS SRAM Cell Stability. IEEE Journal of Solid-State Circuits 36(4), 658–665 (2001)Mukhopadhyay, S., et al.: Modeling of Failure Probability and Statistical Design of SRAM Array for Yield Enhancement in Nanoscaled CMOS. IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 24(12), 1859–1880 (2005)Shirvani, P.P., McCluskey, E.J.: PADded Cache: A New Fault-Tolerance Technique for Cache Memories. In: Proceedings of the 17th IEEE VLSI Test Symposium, pp. 440–445 (1999)Wilkerson, C., et al.: Trading off Cache Capacity for Reliability to Enable Low Voltage Operation. In: Proceedings of the 35th Annual International Symposium on Computer Architecture, pp. 203–214 (2008)Agarwal, A., et al.: Process Variation in Embedded Memories: Failure Analysis and Variation Aware Architecture. IEEE Journal of Solid-State Circuits 40(9), 1804–1814 (2005)Ansari, A., et al.: Archipelago: A Polymorphic Cache Design for Enabling Robust Near-Threshold Operation. In: Proceedings of the 17th International Symposium on High Performance Computer Architecture, pp. 539–550 (2011)Nomura, S., et al.: Sampling + DMR: Practical and Low-overhead Permanent Fault Detection. In: Proceedings of the 38th Annual International Symposium on Computer Architecture, pp. 201–212 (2011)Sinharoy, B., et al.: IBM POWER7 multicore server processor. IBM Journal of Research and Development 55(3) (2011)Lorente, V., et al.: Combining RAM technologies for hard-error recovery in L1 data caches working at very-low power modes. In: Proceedings of the Design, Automation, and Test in Europe Conference, pp. 83–88 (2013)Kanter, D.: Intel’s Haswell CPU Microarchitecture, ”Real World Technologies” (November 13, 2012), http://www.realworldtech.com/haswell-cpu/Paul, S., et al.: Reliability-Driven ECC Allocation for Multiple Bit Error Resilience in Processor Cache. IEEE Transactions on Computers 60(1), 20–34 (2011)Alameldeen, A.R., et al.: Adaptive Cache Design to Enable Reliable Low-Voltage Operation. IEEE Transactions on Computers 60, 50–63 (2011)Dreslinski, R.G., et al.: Reconfigurable Energy Efficient Near Threshold Cache Architectures. In: Proceedings of the 41st Annual IEEE/ACM International Symposium on Microarchitecture, pp. 459–470 (2008)Wilkerson, C., et al.: Reducing Cache Power with Low-Cost, Multi-bit Error-Correcting Codes. In: Proceedings of the 37th Annual International Symposium on Computer Architecture, pp. 83–93 (2010)Burger, D., Austin, T.M.: The SimpleScalar Tool Set, Version 2.0. ACM SIGARCH Computer Architecture News 25(3), 13–25 (1997)Thoziyoor, S., et al.: CACTI 5.1. Hewlett-Packard Laboratories, Palo Alto, Technical Report (2008)spec2000: Standard Performance Evaluation Corporation, http://www.spec.org/cpu2000Kulkarni, J.P., et al.: A 160 mV, Fully Differential, Robust Schmitt Trigger Based Sub-threshold SRAM. In: Proceedings of the ACM/IEEE International Symposium on Low Power Electronics and Design, pp. 171–176 (2007)Keeth, B., et al.: DRAM Circuit Design. Fundamental and High-Speed Topics. John Wiley and Sons, Inc., Hoboken (2008)Mueller, W., et al.: Challenges for the DRAM Cell Scaling to 40nm. In: IEEE International Electron Devices Meeting 4, pp. 336–339 (2005
Feshbach resonances in a quasi-2D atomic gas
Strongly confining an ultracold atomic gas in one direction to create a
quasi-2D system alters the scattering properties of this gas. We investigate
the effects of confinement on Feshbach scattering resonances and show that
strong confinement results in a shift in the position of the Feshbach resonance
as a function of the magnetic field. This shift, as well as the change of the
width of the resonance, are computed. We find that the resonance is strongly
damped in the thermal gas, but in the condensate the resonance remains sharp
due to many-body effects. We introduce a 2D model system, suited for the study
of resonant superfluidity, and having the same scattering properties as the
tightly confined real system near a Feshbach resonance. Exact relations are
derived between measurable quantities and the model parameters.Comment: 8 pages, 2 figure
Energy band structure and intrinsic coherent properties in two weakly linked Bose Einstein Condensates
The energy band structure and energy splitting due to quantum tunneling in
two weakly linked Bose-Einstein condensates were calculated by using the
instanton method. The intrinsic coherent properties of Bose Josephson junction
were investigated in terms of energy splitting. For , the
energy splitting is small and the system is globally phase coherent. In the
opposite limit, , the energy splitting is large and the
system becomes a phase dissipation. Our reslults suggest that one should
investigate the coherence phenomna of BJJ in proper condition such as
.Comment: to appear in Phys. Rev. A, 2 figure
Serum- and bone-mineral status of ostriches with tibiotarsal rotation
Tibiotarsal rotation in ostrich chicks is a serious problem that accounts for considerable financial loss to ostrich farmers. Serum- and bone-mineral analyses of 20 ostrich chicks with tibiotarsal rotation were compared with serum- and bone-mineral analyses of eight normal ostrich chicks of comparable age, sex and body mass, and raised under identical conditions. The serum-zinc values were significantly higher and the bone-calcium and phosphorus values significantly lower in the affected group than in the group of normal ostrich chicks. The results indicated poor mineralization of bone with subsequent reactive osteoid formation.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201
The Bogoliubov Theory of a BEC in Particle Representation
In the number-conserving Bogoliubov theory of BEC the Bogoliubov
transformation between quasiparticles and particles is nonlinear. We invert
this nonlinear transformation and give general expression for eigenstates of
the Bogoliubov Hamiltonian in particle representation. The particle
representation unveils structure of a condensate multiparticle wavefunction. We
give several examples to illustrate the general formalism.Comment: 10 pages, 9 figures, version accepted for publication in Phys. Rev.
Sperm-storage tubules in the vagina of the ostrich (Struthio camelus)
Sperm-storage tubules have been described in a number of species of birds. The presence of these
tubules in the Rhea has been mentioned, but no description of these structures in ratites is available.
The purpose of this study was to determine the presence and morphology of sperm-storage tubules in
the vagina of the ostrich. The study was performed with the use of conventional light- and electron-microscopic
techniques. Sperm-storage tubules were located in a 200-mm-wide band of the vagina adjacent
to the utero-vaginal junction. The tubules were mostly branched and slightly coiled and lined by
columnar epithelial cells. The cells contained a basal nucleus and displayed extensive apical junctional
complexes. TEM revealed sperm in all the tubules examined.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201
Evidence for cryptosporidial infection as a cause of prolapse of the phallus and cloaca in ostrich chicks (Struthio camelus)
Cloacas of male ostrich chicks that had suffered prolapse of the phallus and cloaca were compared
with cloacas of normal ostrich chicks of both sexes from the same area. Heavy infection of the cloacal
and bursal tissue with Cryptosporidium sp. was present in all the cases of prolapse, while no cryptosporidia
were observed in the normal chicks. Histopathological lesions as described in cryptosporidial
infection in other species were present in the infected cloacas. These included loss of the microvillous
border and epithelial hyperplasia, and degeneration, which was indicated ultrastructurally by vacuolation
of the apical cytoplasm, swelling of organelles, and nuclear changes. It is suggested that these lesions,
in combination with the anatomy of the male ostrich cloaca, may be responsible for prolapse of the
phallus and cloaca.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201
Direct observation by resonant tunneling of the B^+ level in a delta-doped silicon barrier
We observe a resonance in the conductance of silicon tunneling devices with a
delta-doped barrier. The position of the resonance indicates that it arises
from tunneling through the B^+ state of the boron atoms of the delta-layer.
Since the emitter Fermi level in our devices is a field-independent reference
energy, we are able to directly observe the diamagnetic shift of the B^+ level.
This is contrary to the situation in magneto-optical spectroscopy, where the
shift is absorbed in the measured ionization energy.Comment: submitted to PR
Cassini UVIS Observations of the Io Plasma Torus. IV. Modeling Temporal and Azimuthal Variability
In this fourth paper in a series, we present a model of the remarkable
temporal and azimuthal variability of the Io plasma torus observed during the
Cassini encounter with Jupiter. Over a period of three months, the Cassini
Ultraviolet Imaging Spectrograph (UVIS) observed a dramatic variation in the
average torus composition. Superimposed on this long-term variation, is a
10.07-hour periodicity caused by an azimuthal variation in plasma composition
subcorotating relative to System III longitude. Quite surprisingly, the
amplitude of the azimuthal variation appears to be modulated at the beat
frequency between the System III period and the observed 10.07-hour period.
Previously, we have successfully modeled the months-long compositional change
by supposing a factor of three increase in the amount of material supplied to
Io's extended neutral clouds. Here, we extend our torus chemistry model to
include an azimuthal dimension. We postulate the existence of two azimuthal
variations in the number of super-thermal electrons in the torus: a primary
variation that subcorotates with a period of 10.07 hours and a secondary
variation that remains fixed in System III longitude. Using these two hot
electron variations, our model can reproduce the observed temporal and
azimuthal variations observed by Cassini UVIS.Comment: Revised 24 August 2007 Accepted by Icarus, 50 pages, 2 Tables, 8
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