Chaotic Inflation with Time-Variable Space Dimensions

Assuming the space dimension is not constant but decreases during the expansion of the Universe, we study chaotic inflation with the potential $m^2\phi^2/2$. Our investigations are based on a model Universe with variable space dimensions. We write down field equations in the slow-roll approximation, and define slow-roll parameters by assuming the number of space dimensions decreases continuously as the Universe expands. The dynamical character of the space dimension shifts the initial and final value of the inflaton field to larger values. We obtain an upper limit for the space dimension at the Planck length. This result is in agreement with previous works for the effective time variation of the Newtonian gravitational constant in a model Universe with variable space dimensions.Comment: 19 pages, To be published in Int.J.Mod.Phys.D. Minor changes to match accepted versio

A novel non-intrusive microcell for sound-speed measurements in liquids. Speed of sound and thermodynamic properties of 2-propanone at pressures up to 160 MPa

A novel high-pressure, ultrasonic cell of extremely reduced internal dimensions ( 0.8 10 6 m3) and good precision for the determination of the speed of propagation of sound in liquids was conceived and built. It makes use of a non-intrusive methodology where the ultrasonic transducers are not in direct contact with the liquid sample under investigation. The new cell was used to carry out speed of sound measurements in 2-propanone (acetone) in broad ranges of temperature (265 < T =K < 340) and pressure (0:1 < p=MPa < 160). (p; q; T ) data for acetone were also determined but in a narrower T ; p range (298 to 333 K; 0.1 to 60 MPa). In this interval, several thermodynamic properties were thus calculated, such as: isentropic (js) and isothermal (jTÞ compressibility, isobaric thermal expansivity (ap), isobaric (cp) and isochoric (cv) specific heat capacity, and the thermal pressure coefficient (cv). Comparisons with values found in the literature generally show good agreement.info:eu-repo/semantics/publishedVersio

Geometry of dynamics, Lyapunov exponents and phase transitions

The Hamiltonian dynamics of classical planar Heisenberg model is numerically investigated in two and three dimensions. By considering the dynamics as a geodesic flow on a suitable Riemannian manifold, it is possible to analytically estimate the largest Lyapunov exponent in terms of some curvature fluctuations. The agreement between numerical and analytical values for Lyapunov exponents is very good in a wide range of temperatures. Moreover, in the three dimensional case, in correspondence with the second order phase transition, the curvature fluctuations exibit a singular behaviour which is reproduced in an abstract geometric model suggesting that the phase transition might correspond to a change in the topology of the manifold whose geodesics are the motions of the system.Comment: REVTeX, 10 pages, 5 PostScript figures, published versio

No maintenance -- no energy efficiency

Field investigations illustrate that it is not realistic to expect new high-tech equipment to function for a full life expectancy at high efficiency without significant operations and maintenance (O&M). A simple walk through inspection of most buildings reveals extensive equipment that is being operated on manual override, is incorrectly adjusted and operating inefficiently, or is simply inoperative. This point is illustrated with two examples at Robins Air Force Base, Georgia. The first describes development of a comprehensive, base-wide, steam trap maintenance program. The second describes a measured evaluation from a typical office building. The objective of both examples was to assess the importance of proper O&M. The proposed ``O&M First`` philosophy will result in more efficient building HVAC operation, provide improved services to the building occupants, and reduce energy consumption and unscheduled equipment repair/replacement. Implementation of a comprehensive O&M program will result in a 15--25% energy savings. The O&M foundation that is established will allow other energy conservation activities such is demand side management or energy management and control systems, to achieve and maintain their expected energy savings

Thermophysical and thermodynamic properties of ionic liquids over an extended pressure range: [bmim][NTf2] and [hmim][NTf2]

The current study focuses on 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [bmim][NTf2], and 1-hexyl-3- methylimidazolium bis(trifluoromethylsulfonyl)amide, [hmim][NTf2]. The objective is to study the influence of pressure as well as that of the cation s alkyl chain length on several properties of this type of ionic liquids. Speed of propagation of ultrasound waves and densities in pure ionic liquids (ILs) as a function of temperature and pressure have been determined. Several other thermody namic properties such as compressibilities, expansivities and heat capacities have been obtained. Speed of sound measurements have been carried out in broad ranges of temperature (283 < T/K < 323) and pressure (0.1 < p/MPa < 150), using a non-intrusive micro cell. Density measurements have been performed at broad ranges of temperature (298 < T/K < 333) and pressure (0.1 < p/MPa < 60) using a vibrating tube densimeter. The pressure dependence of heat capacities, which is generally mild, is highly dependent on the curvature of the temperature dependence of density.info:eu-repo/semantics/publishedVersio

Advanced metering techniques in the federal sector

The lack of utility metering in the federal sector has hampered introduction of direct billing of individual activities at most military installations. Direct billing will produce accountability for the amount of energy used and is a positive step toward self-directed energy conservation. For many installations, automatic meter reading (AMR) is a cost-effective way to increase the number of meters while reducing labor requirements and providing energy conservation analysis capabilities. The communications technology used by some of the AMR systems provides other demand-side management (DSM) capabilities. This paper summarizes the characteristics and relative merits of several AMR/DSM technologies that may be appropriate for the federal sector. A case study of an AMR system being installed at Fort Irwin, California, describes a cost-effective two-way radio communication system used for meter reading and load control

Cosmological zoo -- accelerating models with dark energy

ecent observations of type Ia supernovae indicate that the Universe is in an accelerating phase of expansion. The fundamental quest in theoretical cosmology is to identify the origin of this phenomenon. In principle there are two possibilities: 1) the presence of matter which violates the strong energy condition (a substantial form of dark energy), 2) modified Friedmann equations (Cardassian models -- a non-substantial form of dark matter). We classify all these models in terms of 2-dimensional dynamical systems of the Newtonian type. We search for generic properties of the models. It is achieved with the help of Peixoto's theorem for dynamical system on the Poincar{\'e} sphere. We find that the notion of structural stability can be useful to distinguish the generic cases of evolutional paths with acceleration. We find that, while the $\Lambda$CDM models and phantom models are typical accelerating models, the cosmological models with bouncing phase are non-generic in the space of all planar dynamical systems. We derive the universal shape of potential function which gives rise to presently accelerating models. Our results show explicitly the advantages of using a potential function (instead of the equation of state) to probe the origin of the present acceleration. We argue that simplicity and genericity are the best guide in understanding our Universe and its acceleration.Comment: RevTeX4, 23 pages, 10 figure

Measured energy savings from using night temperature setback

The measured energy savings resulting from using night temperature setback in typical light-construction wooden office buildings was determined. Researchers installed monitoring equipment in a six-building sample of two-story wooden buildings at Fort Devens, Massachusetts. Data obtained during both single-setting and night-setback operating modes were used to develop models of each building`s heat consumption as a function of the difference between inside and outside temperature. These models were used to estimate seasonal savings that could be obtained from the use of night-setback thermostat control. The measured savings in heating energy from using night temperature setback for the six Fort Devens buildings ranged from 14% to 25%; the mean savings was 19.2%. Based on an energy cost of $0.65/therm of natural gas, the estimated average cost savings of using automatic setback thermostats in these buildings is$780 per year per building

The trace left by signature-change-induced compactification

Recently, it has been shown that an infinite succession of classical signature changes (''signature oscillations'') can compactify and stabilize internal dimensions, and simultaneously leads, after a coarse graining type of average procedure, to an effective (''physical'') space-time geometry displaying the usual Lorentzian metric signature. Here, we consider a minimally coupled scalar field on such an oscillating background and study its effective dynamics. It turns out that the resulting field equation in four dimensions contains a coupling to some non-metric structure, the imprint of the ''microscopic'' signature oscillations on the effective properties of matter. In a multidimensional FRW model, this structure is identical to a massive scalar field evolving in its homogeneous mode.Comment: 15 pages, LaTeX, no figure