Application of the direct Liapunov method to the problem of symmetric stability in the atmosphere

The problem of symmetric stability is examined within the context of the direct Liapunov method. The sufficient conditions for stability derived by Fjørtoft are shown to imply finite-amplitude, normed stability. This finite-amplitude stability theorem is then used to obtain rigorous upper bounds on the saturation amplitude of disturbances to symmetrically unstable flows.By employing a virial functional, the necessary conditions for instability implied by the stability theorem are shown to be in fact sufficient for instability. The results of Ooyama are improved upon insofar as a tight two-sided (upper and lower) estimate is obtained of the growth rate of (modal or nonmodal) symmetric instabilities.The case of moist adiabatic systems is also considered

Detection of broken rotor bar faults and effects of loading in induction motors during rundown

© Copyright 2007 IEEEThe detection of broken rotor bar faults based on the common steady-state Fourier transform technique is known to be dependent on the loading condition and the quality of the supply. This paper attempts to minimise these issues by utilising the induced voltage in the stator windings after supply disconnection. When the supply is disconnected, the stator current rapidly drops to zero and the only source of the stator induced voltage an instant after the supply disconnection is due to currents in the rotor. The rotor currents are sensitive to broken rotor bar faults and directly affect the rundown induced voltage in the stator windings. The performance of two different broken rotor bar detection techniques, based on the Fourier transform and the wavelet transform, are investigated over a wide range of loading conditions

A small source in Q2237+0305 ?

Microlensing in Q2237+0305 between 1985 and 1995 (eg. Irwin et al. 1989; Corrigan et al. 1991; Ostensen et al. 1996) has been interpreted in two different ways; as microlensing by stellar mass objects of a continuum source having dimensions significantly smaller than the microlens Einstein radius (ER) (eg. Wambsganss, Paczynski & Schneider 1990; Rauch & Blandford 1991), and as microlensing by very low mass objects of a source as large as 5 ER (Refsdal & Stabell 1993; Haugan 1996). In this paper we present evidence in favour of a small source. Limits on the source size (in units of ER) are obtained from the combination of limits on the number of microlens Einstein radii crossed by the source during the monitoring period with two separate light-curve features. Firstly, recently published monitoring data (Wozniak et al. 2000; OGLE web page) show large variations (~0.8-1.5 magnitudes) between image brightnesses over a period of 700 days or ~15% of the monitoring period. Secondly, the 1988 peak in the image A light-curve had a duration that is a small fraction (<0.02) of the monitoring period. Such rapid microlensing rises and short microlensing peaks only occur for small sources. We find that the observed large-rapid variation limits the source size to be <0.2 ER (95% confidence). The width of the light-curve peak provides a stronger constraint of <0.02 ER (99% confidence). The Einstein radius (projected into the source plane) of the average microlens mass (m) in Q2237+0305 is ER ~ 10^{17}\sqrt{m} cm. The interpretation that stars are responsible for microlensing in Q2237+0305 therefore results in limits on the continuum source size that are consistent with current accretion disc theory.Comment: 8 pages, 3 figures, accepted for publication in M.N.R.A.

Investigation of static eccentricity fault frequencies using multiple sensors in induction motors and effects of loading

A significant number of studies have been reported in the literature on the detection of eccentricity faults in induction machines; however these have generally used one type of sensor such as current or vibration, and not studied in detail the effect of loading. This paper examines the use of fault frequency components in the current, flux and vibration sensor signals with the aim of both detecting and estimating the severity of static eccentricity faults in the presence of load variations. The research is based on an extensive series of sensor measurements taken using a specially modified 2.2kW induction machine under varying conditions of static eccentricity and loading.R. Supangat, J. Grieger, N. Ertugrul, W.L. Soong, D.A. Gray, C. Hanse

Using Estrus-Detection Patches to Vary Time of Insemination Improves Pregnancy Rates Compared with One Single Timed Insemination

Timed artificial insemination (TAI) of beef cows at a predetermined time is a management tool that reduces labor costs associated with conventional heat detection before insemination. Multiple research trials have examined timing of the individual components of the developed protocols associated with TAI. The 7-day CO-Synch + progesterone insert (controlled internal drug release; CIDR) protocol has been shown to initiate ovulation effectively in cycling and noncycling suckled beef cows, often producing pregnancy rates greater than 50% in beef cows. In the current research, we examined using two targeted insemination intervals depending on the occurrence of estrus. We hypothesized that by more closely synchronizing estrus and insemination that pregnancy rates would be increased. We further hypothesized that cows that do not demonstrate estrus and are subjected to a TAI protocol might benefit from an increased interval to insemination

Using Estrus-Detection Patches to Vary Time of Insemination Improves Pregnancy Rates Compared with One Single Timed Insemination

Timed artificial insemination (TAI) of beef cows at a predetermined time is a management tool that reduces labor costs associated with conventional heat detection before insemination. Multiple research trials have examined timing of the individual components of the developed protocols associated with TAI. The 7-day CO-Synch + progesterone insert (controlled internal drug release; CIDR) protocol has been shown to initiate ovulation effectively in cycling and noncycling suckled beef cows, often producing pregnancy rates greater than 50% in beef cows. In the current research, we examined using two targeted insemination intervals depending on the occurrence of estrus. We hypothesized that by more closely synchronizing estrus and insemination that pregnancy rates would be increased. We further hypothesized that cows that do not demonstrate estrus and are subjected to a TAI protocol might benefit from an increased interval to insemination

Progress of the Felsenkeller shallow-underground accelerator for nuclear astrophysics

Low-background experiments with stable ion beams are an important tool for putting the model of stellar hydrogen, helium, and carbon burning on a solid experimental foundation. The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso, using a 0.4 MV accelerator. In the present contribution, the status of the project for a higher-energy underground accelerator is reviewed. Two tunnels of the Felsenkeller underground site in Dresden, Germany, are currently being refurbished for the installation of a 5 MV high-current Pelletron accelerator. Construction work is on schedule and expected to complete in August 2017. The accelerator will provide intense, 50 uA, beams of 1H+, 4He+, and 12C+ ions, enabling research on astrophysically relevant nuclear reactions with unprecedented sensitivity.Comment: Submitted to the Proceedings of Nuclei in the Cosmos XIV, 19-24 June 2016, Niigata/Japa

Comparing the nutritional impact of dietary strategies to reduce discretionary choice intake in the Australian adult population: a simulation modelling study

Published: 3 May 2017. Corrected by: Erratum: Grieger, J.A.; et al.: Comparing the Nutritional Impact of Dietary Strategies to Reduce Discretionary Choice Intake in the Australian Adult Population: A Simulation Modelling Study. Nutrients 2017, 9, 442, in Vol. 9, Issue 8, 851. There was anerror in the median intake ratio calculation used in the substitution strategies. The median intake ratios have been corrected throughout Supplementary Table S1. The corrected calculations have led to minor changes (i.e., less than 5% change in nutrient intakes) to results reported in the abstract (page 1), the substitution results text (page 8 and 9), tables and figures (Table 2, columns 4 and 5, page 8; Figure 1, light green and dark green bars, page 6; Figure 2, green bars page 7; Supplementary Table S1, substitution replacement rows; Supplementary Table S3, columns 4–8; and Supplementary Table S6, columns 2 and 3). The corrected tables and text are shown below. These changes have no material impact on the conclusions of our paper. We apologize for any inconvenience caused. The manuscript will be updated and the original will remain online on the article website.Dietary strategies to reduce discretionary choice intake are commonly utilized in practice, but evidence on their relative efficacy is lacking. The aim was to compare the potential impact on nutritional intake of three strategies to reducing discretionary choices intake in the Australian adult (19–90 years) population. Dietary simulation modelling using data from the National Nutrition and Physical Activity Survey 2011–2012 was conducted (n = 9341; one 24 h dietary recall). Strategies modelled were: moderation (reduce discretionary choices by 50%, with 0%, 25% or 75% energy compensation); substitution (replace 50% of discretionary choices with core choices); reformulation (replace 50% SFA with unsaturated fats, reduce added sugars by 25%, and reduce sodium by 20%). Compared to the base case (observed) intake, modelled intakes in the moderation scenario showed: −17.3% lower energy (sensitivity analyses, 25% energy compensation −14.2%; 75% energy compensation −8.0%), −20.9% lower SFA (−17.4%; −10.5%), −43.3% lower added sugars (−41.1%; −36.7%) and 17.7% lower sodium (−14.3%; −7.5%). Substitution with a range of core items, or with fruits, vegetables and core beverages only, resulted in similar changes in energy intake (−13.5% and −15.4%), SFA (−17.7% and −20.1%), added sugars (−42.6% and −43%) and sodium (−13.7% and −16.5%), respectively. Reformulating discretionary choices had minimal impact on reducing energy intake but reduced SFA (−10.3% to −30.9%), added sugars (−9.3% to −52.9%), and alcohol (−25.0% to −49.9%) and sodium (−3.3% to −13.2%). The substitution and reformulation scenarios minimized negative changes in fiber, protein and micronutrient intakes. While each strategy has strengths and limitations, substitution of discretionary choices with core foods and beverages may optimize the nutritional impact.Jessica A. Grieger, Brittany J. Johnson, Thomas P. Wycherley and Rebecca K. Golle

The new Felsenkeller 5 MV underground accelerator

The field of nuclear astrophysics is devoted to the study of the creation of the chemical elements. By nature, it is deeply intertwined with the physics of the Sun. The nuclear reactions of the proton-proton cycle of hydrogen burning, including the 3He({\alpha},{\gamma})7Be reaction, provide the necessary nuclear energy to prevent the gravitational collapse of the Sun and give rise to the by now well-studied pp, 7Be, and 8B solar neutrinos. The not yet measured flux of 13N, 15O, and 17F neutrinos from the carbon-nitrogen-oxygen cycle is affected in rate by the 14N(p,{\gamma})15O reaction and in emission profile by the 12C(p,{\gamma})13N reaction. The nucleosynthetic output of the subsequent phase in stellar evolution, helium burning, is controlled by the 12C({\alpha},{\gamma})16O reaction. In order to properly interpret the existing and upcoming solar neutrino data, precise nuclear physics information is needed. For nuclear reactions between light, stable nuclei, the best available technique are experiments with small ion accelerators in underground, low-background settings. The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso/Italy, using a 0.4 MV accelerator. The present contribution reports on a higher-energy, 5.0 MV, underground accelerator in the Felsenkeller underground site in Dresden/Germany. Results from {\gamma}-ray, neutron, and muon background measurements in the Felsenkeller underground site in Dresden, Germany, show that the background conditions are satisfactory for nuclear astrophysics purposes. The accelerator is in the commissioning phase and will provide intense, up to 50{\mu}A, beams of 1H+, 4He+ , and 12C+ ions, enabling research on astrophysically relevant nuclear reactions with unprecedented sensitivity.Comment: Submitted to the Proceedings of the 5th International Solar Neutrino Conference, Dresden/Germany, 11-14 June 2018, to appear on World Scientific -- updated version (Figure 2 and relevant discussion updated, co-author A. Domula added