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A large theoretical literature in sociology connects increases in incarceration to contractions in the demand for labor. But previous research on how the labor market affects incarceration is often functionalist and seldom causal. This article estimates the effect of a shock to the southern agricultural labor market during a time when planters exerted a clear influence over whether workers or potential workers were incarcerated. From 1915 to 1920, a beetle called the boll weevil spread across the state of Georgia, causing cotton yields and the demand for agricultural workers to fall. Using archival records of incarceration in Georgia, the authors find that the boll weevil infestation increased the Black prison admission rate for property crimes by more than a third. The article describes the institutional conditions under which falling labor demand should increase incarceration, clarifies the relationship between incarceration and the economic institutions that replaced slavery, and contributes to a growing literature on incarceration and exploitation in the labor market.

The stability and control characteristics of two twin-lift helicopter configurations are analyzed in this paper. In order to address the issue of configuration selection from a handling qualities viewpoint, their open-and closed-loop characteristics are compared. The two twin-lift configurations considered are the twin-lift with spreader bar and twin-lift without spreader bar. The nonlinear models describing the dynamics of these two configurations in the lateral/vertical plane are derived. The open-loop characteristics of the two systems are compared by linearizing the nonlinear models about a symmetric hovering equilibrium condition. The closed-loop characteristics of the two systems are compared using nonlinear controllers based on feedback linearization schemes. The performance of the resulting closed-loop systems in carrying out a typical twin-lift mission is evaluated through nonlinear simulation. Also, the effects of helicopter performance degradation and measurement errors on the overall system performance are discussed.

An integrated design and manufacturing approach allows economic decisions to be made that reflect an entire system design as a whole. To achieve this objective, we have developed and utilized integrated cost and engineering models within a focused design perspective. A framework for the integrated design of an aircraft system with a combined performance and economic perspective is described in this article. This framework is based on the concept of Design Justification using a Design-for-Economics approach. We have developed a knowledge-based system that can be used to evaluate aircraft structural concept material and process selections. The framework consists of the knowledge-based system, integrated with numerical analysis tools including an aircraft performance/sizing code and a life-cycle cost analysis code. Production cost estimates are applied for evaluation of process trades at the subcomponent level of design. Life-cycle cost estimates are used for evaluation of process trades at the system level. Results of a case study are presented for several advanced wing structural concepts for a future supersonic commercial transport aircraft. Cost versus performance studies indicate that a high-speed civil transport aircraft with a hybrid wing structural concept, though more expensive to manufacture than some homogeneous concepts, can have lower direct operating costs due to a lower take-off gross weight and less mission fuel required.

Computing architectures are being assembled that extend concurrent engineering practices by providing more efficient execution and collaboration on distributed, heterogeneous computing networks Built on the successes of Initial architectures, requirements for a next- generation design computing infrastructure can be developed These requirements concentrate on those needed by a designer in decision mak ing processes from product conception to recycling and can be categorized in two areas design process and design information management A designer both designs and executes design processes throughout design time to achieve better product and process capabilities while ex pending fewer resources In order to accomplish this, information, or more appropriately design knowledge, needs to be adequately managed during product and process decomposition as well as recomposition A foundation has been laid that captures these requirements in a design architecture called DRE AMS (Developing Robust Engineering Analysis Models and Specifications) In addition, a computing infrastructure, called IMAGE (Intelligent Multidisciplinary Aircraft Generation Environment), is being developed that satisfies design requirements defined in DREAMS and incorporates enabling computational technologies