Electrical characteristics of a free-burning direct-current argon arc operating between 90 and 563 kilowatts with two types of cathodes

The electrical characteristics of a high-power, long-lived, free-burning dc argon arc are presented. Empirical formulas relating voltage to current, electrode separation, and operating pressure are given for two types of cathodes: a typical point tip cathode and a cathode with a 1.27-cm-(0.5-in.-) diameter crater in the tip. Power was varied from 90 to 563 kW. A discussion of the cathode with the crater tip is given

Existence Advertising, Price Competition, and Asymmetric Market Structure

We examine a two stage duopoly game in which firms advertise their existence to consumers in stage 1 and compete in prices in stage 2. Whenever the advertising technology generates positive overlap in customer bases the equilib- rium for the stage 1 game is asymmetric in that one firm chooses to remain small in comparison to its competitor. For a specific random advertising technology we show that one firm will always be half as large as the other. No equilibrium in pure price strategies exists in the stage 2 game and as long as there is some overlap in customer bases the mixed strategy equilibrium is far from the Bertrand equilibrium.Existence advertising; price dispersion; Bertrand paradox; information; duopoly

Spam - solutions and their problems

We analyze the success of filtering as a solution to the spam problem when used alone or concurrently with sender and/or receiver pricing. We find that filters alone may exacerbate the spam problem if the spammer attempts to evade them by sending multiple variants of the message to each consumer. Sender and receiver prices can effectively reduce or eliminating spam, either on their own or when used together with filtering. Finally, we discuss the impli- cations for social welfare of using the different spam controls.Spam; filtering; email; receiver pricing; sender pricing

Effects of outdoor exposure on solar cell modules in the ERDA/NASA Lewis Research Center Systems Test Facility

The effects of outdoor exposure were determined by comparing standard I-V data obtained for the as-received modules with similar data obtained after removal from the field and cleaning with detergent solution. All modules measured in this way exhibited nonrecoverable degradation in P sub maximum varying from 4 to 7 percent. One module exposed for 41 days exhibited partial cell discoloration, loss of front surface metallization over the discolored portion, and a decrease in P sub maximum of 7 percent, tentatively attributed to cell damage. Measurements before and after cleaning showed a recoverable degradation due to dirt accumulation. This recoverable loss in power was 11 percent after 245 days in the field for one brand of module, 6 percent after 48 days for another brand, and 4 1/2 percent for the third brand

Design considerations for lunar base photovoltaic power systems

A survey was made of factors that may affect the design of photovoltaic arrays for a lunar base. These factors, which include the lunar environment and system design criteria, are examined. A photovoltaic power system design with a triangular array geometry is discussed and compared to a nuclear reactor power systems and a power system utilizing both nuclear and solar power sources

Housing insecurity among urban fathers

This article examines housing insecurity among an understudied population: urban fathers of young children. Housing security is of particular importance for vulnerable populations, and urban fathers, many of whom face unemployment and monitoring from the child support and criminal justice systems, often rely on this security to mitigate the socioeconomic challenges they face. By assessing the extent and type of housing insecurity affecting urban fathers, we identify a potentially serious source of disadvantage facing families more broadly. A year after the birth of a new child, fully a quarter of fathers reported significant housing insecurities with 3% experiencing homelessness. Results suggest that from 9-12% of fathers are doubling up, relying on others for living expenses, and moving more than once every year. Finally, only half of fathers had been able to maintain housing security over the three to four years since the focal child's birth

A sort of homecoming : incarceration and the housing security of urban men

While individuals returning from prison face many barriers to successful re-entry, among the most serious are the challenges they face in securing housing. Housing has long been recognized as a prerequisite for stable employment, access to social services, and other aspects of individual and family functioning. The formerly incarcerated face several administrative and de facto restrictions on their housing options; however, little is known about the unique instabilities that they face. We use a longitudinal survey of urban families to examine housing insecurity among nearly 3,000 urban men, including over 1,000 with incarceration histories. We find that men recently incarcerated face greater housing insecurity, including both serious hardships such as homelessness, and precursors to homelessness such as residential turnover and relying on others for housing expenses. Their increased risk is tied both to diminished annual earnings and other factors, including, potentially, evictions from public housing supported by Federal "one-strike" policies

Calibration of Computational Models with Categorical Parameters and Correlated Outputs via Bayesian Smoothing Spline ANOVA

It has become commonplace to use complex computer models to predict outcomes in regions where data does not exist. Typically these models need to be calibrated and validated using some experimental data, which often consists of multiple correlated outcomes. In addition, some of the model parameters may be categorical in nature, such as a pointer variable to alternate models (or submodels) for some of the physics of the system. Here we present a general approach for calibration in such situations where an emulator of the computationally demanding models and a discrepancy term from the model to reality are represented within a Bayesian Smoothing Spline (BSS) ANOVA framework. The BSS-ANOVA framework has several advantages over the traditional Gaussian Process, including ease of handling categorical inputs and correlated outputs, and improved computational efficiency. Finally this framework is then applied to the problem that motivated its design; a calibration of a computational fluid dynamics model of a bubbling fluidized which is used as an absorber in a CO2 capture system