Fluid phase analyzer Patent

Mixed liquid and vapor phase analyzer design with thermocouples for relative heat transfer measuremen

Choosing Dielectric or Magnetic Material to Optimize the Bandwidth of Miniaturized Resonant Antennas

We address the question of the optimal choice of loading material for antenna miniaturization. A new approach to identify the optimal loading material, dielectric or magnetic, is presented for resonant antennas. Instead of equivalent resonance circuits or transmission-line models, we use the analysis of radiation to identify the fields contributing mostly to the stored energy. This helps to determine the beneficial material type. The formulated principle is qualitatively illustrated using three antenna types. Guidelines for different antenna types are presented.Comment: 17 pages, 9 figure

A Review of Thermal Analysis on Novel Roofing Systems

In this paper, we reviewed three types of novel roofing systems which can reduce building thermal loads: cool roof, green roof, and phase change material (PCM) roof. Cool roofs are designed to keep the roof cool by reflecting the incident solar radiation away from the building and radiating the stored heat away at night. Green roof, also called eco-roof, covered by vegetation, utilizes the thermal insulation provided by the soil and evapo-transpiration to keep the roof cool under the sun. PCM roofs employ phase change material with high latent heat of fusion in the roofs. PCM roofs are able to absorb large amount of heat at demand peak when PCM changes its phase, so that the heat from outdoor is stored in the PCM rather than flows into indoor space. The effort in the paper has compared the key parameters of each of the systems, thermal analysis methodologies, and the energy savings due to each of them with reference cases, in addition, we provide a comprehensive thermal analysis methods applied in novel roof systems and a guide to design proper novel roofing system for a give climate and building types

Stored energies for electric and magnetic current densities

Electric and magnetic current densities are an essential part of electromagnetic theory. The goal of the present paper is to define and investigate stored energies that are valid for structures that can support both electric and magnetic current densities. Stored energies normalized with the dissipated power give us the Q factor, or antenna Q, for the structure. Lower bounds of the Q factor provide information about the available bandwidth for passive antennas that can be realized in the structure. The definition that we propose is valid beyond the leading order small antenna limit. Our starting point is the energy density with subtracted far-field form which we obtain an explicit and numerically attractive current density representation. This representation gives us the insight to propose a coordinate independent stored energy. Furthermore, we find here that lower bounds on antenna Q for structures with e.g. electric dipole radiation can be formulated as convex optimization problems. We determine lower bounds on both open and closed surfaces that support electric and magnetic current densities. The here derived representation of stored energies has in its electrical small limit an associated Q factor that agrees with known small antenna bounds. These stored energies have similarities to earlier efforts to define stored energies. However, one of the advantages with this method is the above mentioned formulation as convex optimization problems, which makes it easy to predict lower bounds for antennas of arbitrary shapes. The present formulation also gives us insight into the components that contribute to Chu's lower bound for spherical shapes. We utilize scalar and vector potentials to obtain a compact direct derivation of these stored energies. Examples and comparisons end the paper.Comment: Minor updates to figures and tex