5,699 research outputs found

    An embedded energy monitoring circuit for a 128kbit SRAM with body-biased sense-amplifiers

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    Embedded energy monitoring of critical system components can be used to enable better power management by capturing run time system conditions such as temperature and application load. In this work, an energy sensing circuit that provides digitally represented absolute energy per operation of a 128kbit SRAM is presented. Designed in a 65nm low-power CMOS process, SRAMs can operate down to 370 mV. Energy sensing circuit consumes 16.7μW during sensing at 1.2V (only 0.28% of SRAM active power at the same voltage). For improved performance, SRAMs utilize body-biased PMOS input strong-arm type sense amplifiers that can achieve 45% tighter input offset distribution for only ~3.5% of total SRAM area overhead.United States. Defense Advanced Research Projects Agency. The Ubiquitous High Performance Computing Progra

    Striations in the Taurus molecular cloud: Kelvin-Helmholtz instability or MHD waves?

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    The origin of striations aligned along the local magnetic field direction in the translucent envelope of the Taurus molecular cloud is examined with new observations of 12CO and 13CO J=2-1 emission obtained with the 10~m submillimeter telescope of the Arizona Radio Observatory. These data identify a periodic pattern of excess blue and redshifted emission that is responsible for the striations. For both 12CO and 13CO, spatial variations of the J=2-1 to J=1-0 line ratio are small and are not spatially correlated with the striation locations. A medium comprised of unresolved CO emitting substructures (cells) with a beam area filling factor less than unity at any velocity is required to explain the average line ratios and brightness temperatures. We propose that the striations result from the modulation of velocities and the beam filling factor of the cells as a result of either the Kelvin-Helmholtz instability or magnetosonic waves propagating through the envelope of the Taurus molecular cloud. Both processes are likely common features in molecular clouds that are sub-Alfvenic and may explain low column density, cirrus-like features similarly aligned with the magnetic field observed throughout the interstellar medium in far-infrared surveys of dust emission.Comment: 11 pages, 4 figures. Accepted for publication in MNRA

    Credit default swaps and firms' financing policies

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    This paper examines the impact of credit default swaps (CDS) on firms' financing and trade credit policies. Our results indicate firms with CDS trading on their debt increase their equity issuances. Further, firms with CDS trading on their debt and high levels of long-term debt issuances decrease their debt financing. Total and idiosyncratic risks are also higher for firms with CDS trading on their debt. These firms pay their suppliers and collect from their customers quicker. Thus, the impacts of the CDS market are not limited to the borrowing firms but also affect economically connected firms

    The hot core towards the intermediate mass protostar NGC7129 FIRS 2: Chemical similarities with Orion KL

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    NGC 7129 FIRS 2 (hereafter FIRS 2) is an intermediate-mass (2 to 8 Msun) protostar located at a distance of 1250 pc. High spatial resolution observations are required to resolve the hot core at its center. We present a molecular survey from 218200 MHz to 221800 MHz carried out with the IRAM Plateau de Bure Interferometer. These observations were complemented with a long integration single-dish spectrum taken with the IRAM 30m telescope. We used a Local Thermodynamic Equilibrium (LTE) single temperature code to model the whole dataset. The interferometric spectrum is crowded with a total of ~300 lines from which a few dozens remain unidentified yet. The spectrum has been modeled with a total of 20 species and their isomers, isotopologues and deuterated compounds. Complex molecules like methyl formate (CH3OCHO), ethanol (CH3CH2OH), glycolaldehyde (CH2OHCHO), acetone (CH3COCH3), dimethyl ether (CH3OCH3), ethyl cyanide (CH3CH2CN) and the aGg' conformer of ethylene glycol (aGg'-(CH2OH)_2) are among the detected species. The detection of vibrationally excited lines of CH3CN, CH3OCHO, CH3OH, OCS, HC3N and CH3CHO proves the existence of gas and dust at high temperatures. In fact, the gas kinetic temperature estimated from the vibrational lines of CH3CN, ~405 K, is similar to that measured in massive hot cores. Our data allow an extensive comparison of the chemistry in FIRS~2 and the Orion hot core. We find a quite similar chemistry in FIRS 2 and Orion. Most of the studied fractional molecular abundances agree within a factor of 5. Larger differences are only found for the deuterated compounds D2CO and CH2DOH and a few molecules (CH3CH2CN, SO2, HNCO and CH3CHO). Since the physical conditions are similar in both hot cores, only different initial conditions (warmer pre-collapse phase in the case of Orion) and/or different crossing time of the gas in the hot core can explain this behavior.Comment: 30 pages, 9 figure

    Effect of anisotropy and destructuration on behavior of Haarajoki test embankment

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    This paper investigates the influence of anisotropy and destructuration on the behavior of Haarajoki test embankment, which was built by the Finnish National Road Administration as a noise barrier in 1997 on a soft clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. The construction and consolidation of the embankment is analyzed with the finite-element method using three different constitutive models to represent the soft clay. Two recently proposed constitutive models, namely S-CLAY1 which accounts for initial and plastic strain induced anisotropy, and its extension, called S-CLAY1S which accounts, additionally, for interparticle bonding and degradation of bonds, were used in the analysis. For comparison, the problem is also analyzed with the isotropic modified cam clay model. The results of the numerical analyses are compared with the field measurements. The simulations reveal the influence that anisotropy and destructuration have on the behavior of an embankment on soft clay

    Impact of ambient air filters on PM concentration levels at an urban traffic hotspot (Stuttgart, Am Neckartor)

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    Air pollution can have severe impacts on public health. A novel approach to lower the local particle concentrations at urban hotspots is ambient air filtration. This study presents experimental investigations into the effectiveness of air filters to lower ambient particle concentration levels at two different locations. Seventeen outdoor filtration devices with a total flow rate of 170.000 m³/h were installed beside federal highway B14 at Stuttgart “Am Neckartor” targeting to reduce PM10 concentration levels within a 300 m × 50 m area around the urban pollution hotspot. Further measurements were conducted at the residential area “Bleyle quarter” to show the capabilities of a single filter device under relatively defined conditions. By periodically switching the filters on and off while monitoring the particle mass concentrations with optical particle counters, the effects of the filters on the PM10 and PM2.5 concentration levels were determined. A long term investigation at the Neckartor installation site (466 h) yielded an average PM10 reduction of 10.4% (6.3 μg/m³) at the official Neckartor measurement station. Additional in situ measurement campaigns showed that the PM reduction effect decreases with increasing distance to the filter devices. However, the effect is clearly measurable in the walkway areas across the installation site
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