Sentech Corporation (United States)

During the mid-1970s, following the first oil embargo, heat pumps became of great interest to northern U. S. electric power companies, particularly for those experiencing large peak demands during the heating season, as shortages of natural gas and oil led to increased usage of direct electric heating. Air-source heat pumps (ASHP), given their wider market presence relative to other heat pump types, almost universal applicability, and inherent efficiency and capacity issues at cold outdoor temperatures were of primary interest as an electrical heating system alternative at that time. ASHPs based on the simple vapor compression cycle suffer both heating capacity (output) and efficiency (coefficient of performance or COP) degradation as the outdoor ambient temperature drops.

We report for the first time fabrication of self-aligned hexagonally closed-packed titania nanotube arrays of over 1000 μm in length and aspect ratio ≈10 000 by potentiostatic anodization of titanium. We describe a process by which such thick nanotube array films can be transformed into self-standing, flat or cylindrical, mechanically robust, polycrystalline TiO2 membranes of precisely controlled nanoscale porosity. The self-standing membranes are characterized using Brunauer−Emmett−Teller surface area measurements, glancing angle X-ray diffraction, and transmission electron microscopy. In initial application, such membranes are used to control the diffusion of phenol red.

In this paper we examine the different functions performed by an acoustic-seismic unattended ground sensor (UGS) and how they contribute to the overall cost of the sensor and its implementation. A key point made is that the performance of the acoustic-seismic depends on target characteristics and environmental conditions and cannot easily be traded off against implementation costs. At the present time, sensor implementation costs are dominated by the radios. In general, it is best to use radios whose range is consistent with the detection capabilities of the sensors. Dense networks of sensors using short-range radios supporting distributed communication architecture will produce an unnecessary duplication of coverage and a much-increased cost. Different scenarios for the utilization of acoustic-seismic UGS are examined, and evaluated with respect to their implementation costs. The most cost-effective use of acoustic-seismic sensors is in those applications where they can use satellite communications or tap into an existing communications network.

Contamination of optical elements during photoresist exposure is a serious issue in optical lithography. The outgassing of photoresist has been identified as a problem at 248 nm and 193 nm in production because the organic films that can be formed on an exposure lens can cause transmission loss and severe image distortion. At these exposure energies, the excitation of the photo acid generator, formation of acid, and cleavage of the protecting group are highly selective processes. At 157 nm, the exposure energy is much higher (7.9 eV compared to 6.4 eV at 193 nm) and it is known from laser ablation experiments that direct laser cleavage of sigma bonds occurs. The fragments formed during this irradiation can be considered as effective laser deposition precursors even in the mid ppb level 1 . In this study, methods to quantify photoresist outgassing at 157 nm are discussed. Three criteria have been set up at International SEMATECH to protect lens contamination and to determine the severity of photoresist outgassing. First, we measured film thickness loss as a function of exposure dose for a variety of materials. In a second test we studied the molecular composition of the outgassing fragments with an exposure chamber coupled to a gas chromatograph and a mass spectrometer detector. Our third method was a deposition test of outgassing vapors on a CaF 2 proof-plate followed by analysis using VUV and X-ray photoelectron spectroscopies (XPS). With this technique we found deposits for many different resists. Our main focus is on F- and Si-containing resists. Both material classes form deposits especially if these atoms are bound to the polymer side chains. Whereas the F-containing films can be cleaned off under 157 nm irradiation, cleaning of Si-containing films mainly produces SiO 2 . Our cleaning studies of plasma deposited F-containing organic films on SiO 2 did not indicate damage of this surface by the possible formation of HF. Despite that we strongly recommend engineering measures to overcome contamination by resist, such as optimizing the purge flow between the final lens element and wafer surface or utilization of a lens pellicle.

One can detect and track vehicles and personnel using a three-component seismic velocity transducer. Persons or vehicles moving over ground generate a succession of impacts; these soil disturbances propagate away from the source as seismic waves. Because the soil is an elastic medium both vertical and longitudinal waves propagate, diminishing in intensity as R<SUP>-2</SUP>. Furthermore because the surface of the soil is the boundary of an elastic space, a Rayleigh surface wave is also generated, diminishing in intensity as R<SUP>-1</SUP>. This surface wave is a vector wave that can be used to track the source. In addition to the classic model of surface waves on an elastic half space we discuss special features of seismic measurements. Among these are: contamination of the seismic signal by local acoustic waves, the excess non-geometric attenuation of the seismic signal, the influence of reflections from layered soil in tracking personnel, and finally a method of ranging using the periodic impact signature of vehicles.

This book concentrates on the design of individual parts, that is detail design, leading to the design of machines to meet a statistically quantified requirement of reliability. Here the author shows for the first time that even when material properties are expressed statistically there are some aspects (for example, strain hardening) that are fundamentally deterministic. The steps in the design methodology are given in detail and possible difficulties of implementation are discussed. Reference is also made to the economic optimization of a design. Finally, a general design strategy which ensures a reliable product is formulated.

An application is presented of the methodology used bythe Global Environment Facility (GEF) to measureincremental costs. Incremental cost estimates are usedby the GEF to determine its financial contribution toprojects that protect the global environment, such asinvestments in renewable energy. The importance ofadopting a system-wide view in certain types ofprojects (such as investments in grid-connected power)is illustrated using the case of wind power inMorocco. A narrow plant-by-plant comparison wouldneglect the adjustments in the system expansion planthat may be warranted when one type of plant (e.g., acoal fired thermal plant) is replaced by another (e.g.,a wind farm).

Discusses the characteristics of data broadcasting from the point of view of the Adaptec company with particular reference to DBS-PC (direct broadcast satellite-PC). The data path taken and push technology are discussed. Prospects for the future operation of this system are considered.