Determining the Impact of Wind on System Costs via the Temporal Patterns of Load and Wind Generation

Wind Energy, System Costs, Alternative Energy, Electricity Generation, Environmental Economics and Policy, Resource /Energy Economics and Policy, Q4, Q42, Q54,

Field tests of a portable MEMS gravimeter

Gravimeters are used to measure density anomalies under the ground. They are applied in many different fields from volcanology to oil and gas exploration, but present commercial systems are costly and massive. A new type of gravity sensor has been developed that utilises the same fabrication methods as those used to make mobile phone accelerometers. In this study, we describe the first results of a field-portable microelectromechanical system (MEMS) gravimeter. The stability of the gravimeter is demonstrated through undertaking a multi-day measurement with a standard deviation of 5.58 × 10−6 ms−2 . It is then demonstrated that a change in gravitational acceleration of 4.5 × 10−5 ms−2 can be measured as the device is moved between the top and the bottom of a 20.7 m lift shaft with a signal-to-noise ratio (SNR) of 14.25. Finally, the device is demonstrated to be stable in a more harsh environment: a 4.5 × 10−4 ms−2 gravity variation is measured between the top and bottom of a 275-m hill with an SNR of 15.88. These initial field-tests are an important step towards a chip-sized gravity senso

A High Stability Optical Shadow Sensor with Applications for Precision Accelerometers

Gravimeters are devices which measure changes in the value of the gravitational acceleration, \textit{g}. This information is used to infer changes in density under the ground allowing the detection of subsurface voids; mineral, oil and gas reserves; and even the detection of the precursors of volcanic eruptions. A micro-electro mechanical system (MEMS) gravimeter has been fabricated completely in silicon allowing the possibility of cost e-effective, lightweight and small gravimeters. To obtain a measurement of gravity, a highly stable displacement measurement of the MEMS is required. This requires the development of a portable electronics system that has a displacement sensitivity of $\leq 2.5$ nm over a period of a day or more. The portable electronics system presented here has a displacement sensitivity $\leq 10$ nm$/\sqrt{\textrm{Hz}}$ ($\leq 0.6$ nm at $1000$ s). The battery power system used a modulated LED for measurements and required temperature control of the system to $\pm$ 2 mK, monitoring of the tilt to $\pm$ 2 $\mu$radians, the storage of measured data and the transmission of the data to an external server.Comment: 8 Pages, 12 figures, 5 equations, currently submitted and under review at IEEE Sensors SIE

Microelectromechanical system gravimeters as a new tool for gravity imaging

A microelectromechanical system (MEMS) gravimeter has been manufactured with a sensitivity of 40 ppb in an integration time of 1 s. This sensor has been used to measure the Earth tides: the elastic deformation of the globe due to tidal forces. No such measurement has been demonstrated before now with a MEMS gravimeter. Since this measurement, the gravimeter has been miniaturized and tested in the field. Measurements of the free-air and Bouguer effects have been demonstrated by monitoring the change in gravitational acceleration measured while going up and down a lift shaft of 20.7 m, and up and down a local hill of 275 m. These tests demonstrate that the device has the potential to be a useful field-portable instrument. The development of an even smaller device is underway, with a total package size similar to that of a smartphone

The Luminosity Function of Galaxies in the Las Campanas Redshift Survey

We present the $R$-band luminosity function for a sample of 18678 galaxies, with average redshift $z = 0.1$, from the Las Campanas Redshift Survey. The luminosity function may be fit by a Schechter function with $M^* = -20.29 \pm 0.02 + 5 \log h$, $\alpha = -0.70 \pm 0.05$, and $\phi^* = 0.019 \pm 0.001 \ h^3$~Mpc$^{-3}$, for absolute magnitudes$-23.0 \leq M - 5 \log h \leq -17.5$. We compare our luminosity function to that from other redshift surveys; in particular our normalization is consistent with that of the Stromlo-APM survey, and is therefore a factor of two below that implied by the$b_J \approx 20$bright galaxy counts. Our normalization thus indicates that much more evolution is needed to match the faint galaxy count data, compared to minimal evolution models which normalize at$b_J \approx 20$. Also, we show that our faint-end slope$\alpha = -0.7$, though ``shallower'' than typical previous values$\alpha = -1$, results primarily from fitting the detailed shape of the LCRS luminosity function, rather than from any absence of intrinsically faint galaxies from our survey. Finally, using [OII] 3727 equivalent width$W_{\lambda} = 5$~\AA \ as the dividing line, we find significant differences in the luminosity functions of emission and non-emission galaxies, particularly in their$\alpha$values. Emission galaxies have Schechter parameters$M^* = -20.03 \pm 0.03 + 5 \log h$and$\alpha = -0.9 \pm 0.1$, while non-emission galaxies are described by$M^* = -20.22 \pm 0.02 + 5 \log h$and$\alpha = -0.3 \pm 0.1$. (abridged abstract)Comment: 41 pages, including 13 postscript figures, uses AASTEX v4.0 style files. Important clarification of R-band definition, plus correction of luminosity densities and updated references. Main conclusions unchanged. Final version to appear in Ap

Murraya Paniculata Mediated Synthesis Of CdS Nanoparticles For Potent Biomedical Applications

The leaf extract of Murraya paniculata (MPL) is used to create cadmium sulphide nanoparticles, or CdS NPs and the reducing and stabilizing agent is plant extract. A crucial capping agent in nano production is played by phytochemicals. Analytical methods such as XRD and FTIR are used to characterize CdS NPs. The biomedical applications of prepared CdS NPs were examined, including their anticancer, antifungal, and antibacterial properties. The antibacterial performance was carried out with S.flexneri, C.perfringens, S.typhimurium, and E.faecalis which were all susceptible to the antibacterial action of CdS NPs. At 150µg/ml, S.flexneri and E.faecalis showed a maximum zone of inhibition is 20mm. In addition, A.niger and C.albicans were used to test the antifungal activities, results shows the concentration of 400 µg/ml CdS NPs inhibited the growth of A.flavus (16mm). By using the NRU assay, it was found that the biosynthesized CdS NPs exhibited cytotoxic action against the MCF-7 cell line. Analysis using the NRU assay revealed that treating cell lines with increasing concentrations of NPs had lethal effects. The 24-hour treatment's IC50 was found to be 153.2 µg/ml

A Point's Point of View of Stringy Geometry

The notion of a "point" is essential to describe the topology of spacetime. Despite this, a point probably does not play a particularly distinguished role in any intrinsic formulation of string theory. We discuss one way to try to determine the notion of a point from a worldsheet point of view. The derived category description of D-branes is the key tool. The case of a flop is analyzed and Pi-stability in this context is tied in to some ideas of Bridgeland. Monodromy associated to the flop is also computed via Pi-stability and shown to be consistent with previous conjectures.Comment: 15 pages, 3 figures, ref adde

Low temperature characterization of modulation doped SiGe grown on bonded silicon-on-insulator

Modulation doped pseudomorphic Si0.87Ge0.13 strained quantum wells were grown on bonded silicon-on-insulator (SOI) substrates. Comparison with similar structures grown on bulk Si(100) wafers shows that the SOI material has higher mobility at low temperatures with a maximum value of 16 810 cm 2/V s for 2.05 × 1011 cm – 2 carries at 298 mK. Effective masses obtained from the temperature dependence of Shubnikov–de Haas oscillations have a value of (0.27 ± 0.02) m0 compared to (0.23 ± 0.02) m0 for quantum wells on Si(100) while the cyclotron resonance effective masses obtained at higher magnetic fields without consideration for nonparabolicity effects have values between 0.25 and 0.29 m0. Ratios of the transport and quantum lifetimes, tau/tau q=2.13 ± 0.10, were obtained for the SOI material that are, we believe, the highest reported for any pseudomorphic SiGe modulation doped structure and demonstrates that there is less interface roughness or charge scattering in the SOI material than in metal–oxide–semiconductor field effect transistors or other pseudomorphic SiGe modulation doped quantum wells

The Breakdown of Topology at Small Scales

We discuss how a topology (the Zariski topology) on a space can appear to break down at small distances due to D-brane decay. The mechanism proposed coincides perfectly with the phase picture of Calabi-Yau moduli spaces. The topology breaks down as one approaches non-geometric phases. This picture is not without its limitations, which are also discussed.Comment: 12 pages, 2 figure