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Liquid-vapor phase-change processes are becoming increasingly important in a wide variety of fields ranging from energy conversion, to microelectronics cooling, MEMs devices, and self-assembly. The phase change in these systems is governed by processes that occur at the contact line, where three phases meet. Evidence suggests that alterations of the surface chemistry and surface topography on the nanoscale can be used to dramatically enhance the phase-change process. This article reviews the current state of the art in nanoscale surface modification as applied to the enhancement of evaporative processes.

The optimum use of interfacial free-energy gradients to control fluid flow in small regions naturally leads to simpler passive heat transfer systems. In this context, passive refers to the natural pressure field for fluid flow due to changes in the intermolecular force field resulting from an imposed nonisothermal temperature field. Although the particular constrained vapor bubble (CVB) discussed can be viewed as a large version of a wickless heat pipe, it is a much more general heat transfer concept. Herein, it is an ideal system for the optical study of microscale transport processes in droplet condensation due to interfacial phenomena. This article concerns the movement of a single condensed ethanol sessile drop into a concave liquid film. The intermolecular force is found to be much larger than the gravitational force and dominates condensate removal. A dimensionless force balance for viscous shear stress demonstrates the effect of changes in the contact angle and curvature. A dimensionless difference in free energy is identified as the cause of spontaneous condensate removal

A Constrained Vapor Bubble (CVB) with a relatively large Bond number formed by partially underfilling liquid in an evacuated cavity is capable of high thermal conductance. Il operates on the principle of closed loop phase-change along with capillarity to circulate the working fluid. Analytical investigations were conducted to compare with existing experimental data. A steady-state fluid flow model combined with a two-dimensional heat transfer model was developed and solved to yield key operating parameters ( i.e., temperature and liquid meniscus curvature) of the CVB. The modeling results of the outside wall temperature in the evaporator were found to agree well with the measured experimental data. An area average heat transfer coefficient was used to characterize the heat transfer on the inside wall of the evaporator. The value of this heat transfer coefficient was found to increase with the heat flow rate. The fluid flow model with the heat transfer model in the evaporator to provide the energy balance ...

This document provides a summary of some of the technical solutions for producing anonymous communication on the Internet and presents an argument that anonymity is as much a part of crime prevention as requiring people to provide their names.

The equilibrium and nonequilibrium phenomena associated with a very thin liquid film formed between a vapor bubble and a container are discussed. Numerical examples of the effects of temperature and intermolecular forces on the film thickness and transport processes are presented. For relatively thick films, the sensitivity of experimental measurements to extremely small temperature gradients is found to be large. For extremely thin films, the sensitivity is small. Large superheats and heat fluxes are possible near the contact line. A small amount of adsorbed contamination has a large effect on the film profile. The constrained vapor bubble has both basic uses in the study of thermophysical properties and transport processes, and has applied uses as a heat exchanger.

Hiding the existence of a message can be an important technique in this era of terabit networks. One technique for practicing this obfuscation, Mimic Functions, is derived from Context-Free Grammars and can be as secure as inverting RSA or factoring Blum integers. This paper discusses the implications of the result and presents a practical solution for securely hiding information from inspection.

This paper describes modifications of Huffman coding permitting encryption to accompany compression. The resulting cipher can be used alone or as a first pass to protect systems like the Data Encryption Standard (DES) from an attack by a brute force machine.

Interferometry was used to measure in situ the thickness profiles of evaporating thin films as a function of heat flux for low concentration polystyrenel/cyclohexane solutions. Evaporative heat flow rates per unit width of contact line were calculated based on polynomial fits of interference data, combined with a fluid flow model. Temperature profiles obtained from thermocouple measurements were employed in evaluating macroscopic interline region heat sink capacities using a one-dimensional heat conduction model. Reasonable agreement between evaporative heat fluxes derived from both methods was established. Pure solvent integral heat fluxes were not significantly altered through polymer addition. Fluid flow toward the triple interline to replace that which evaporated resulted in an apparent non-equilibrium phase separation of concentrated polymer solution from the bulk phase; the separation increased with increasing polymer molecular weight and concentration. A substantial rise in the reflectivity beyond ...

A horizontal platinum resistance thermometer, which supported a meniscus above a pool of electrolyte, was used as an electrode. The unique design allows the simultaneous measurement of electrode potential, current, temperature, and heat flow. Results that demonstrate some of the advantages of this experimental electrode design are presented.

A horizontal platinum resistance thermometer, which supported a meniscus above a pool of electrolyte, was used as an electrode. The unique design allowed the simultaneous measurement of electrode potential, current, temperature, and heat flow. Initial results are presented.