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MANY engineers look upon plastics and allied materials as entirely new to the aircraft industry, but such is not the case. Phenol fibre sheet and resin bonded waterproof plywood have been used for years, and acrylic resin sheet has been in use for transparent enclosures for some time past; yet all come under the above category. The primary difference between the past and present uses of these materials is that they are now used in applications where structural loads are involved, while they were previously used only in non‐stressed parts where special characteristics, such as transparency or insulating qualities, were of paramount importance. If these materials are classified according to their major characteristics they fall into three categories; those made with thermosetting resins, those made with thermoplastic resins, and those made with wood veneer. This classification also in a general way divides them according to their principal uses; thermosetting materials being used mostly in the production of relatively small structural parts, the thermoplastics being used mostly for their transparent properties, and the wood veneer materials being used mostly in relatively large structural parts and assemblies.
IN our report of the tenth annual meeting of the Institute of the Aeronautical Sciences we shall not follow precisely the order in which the sessions occurred nor at all times classify the papers in exactly the manner of the meeting. Unfortunately, certain of the papers presented will not be found in our review owing to lack of preprints, but this in no way reflects on the value or timeliness of the papers omitted in the review.
The emergence of climate science denialism in the United States provides a challenge to STS theories of the relationship between scientific expertise and public policy…
The emergence of climate science denialism in the United States provides a challenge to STS theories of the relationship between scientific expertise and public policy because a situation of epistemic rift occurs: the capacity of scientific consensus to establish the grounds of political debate is broken, and the standard circulation of expertise from the scientists and funding from the state is interrupted. Three mechanisms for the containment of scientific expertise are studied: direct intellectual suppression of climate scientists, industry support of contrarian scientists and policymakers, and cutbacks on government research programs that support climate change. This situation politicizes climate scientists, who are drawn into the public sphere as a counterpublic to the effort to contain the circulation of their knowledge in the political field. Although the strategy of contained expertise has been effective in blocking climate legislation at the federal government level in the United States, it may be losing effectiveness, and an emergent alternative strategy based on adaptation may be coming to replace it. Factors that affect the reduction in the capacity to contain the circulation of scientific expertise are also analyzed.
The purpose of this paper is to tackle a satellite module layout design problem (SMLDP). As a complex engineering layout and combinatorial optimization problem, SMLDP…
The purpose of this paper is to tackle a satellite module layout design problem (SMLDP). As a complex engineering layout and combinatorial optimization problem, SMLDP cannot be solved effectively by traditional exact methods. Although evolutionary algorithms (EAs) have shown some promise of tackling SMLDP in previous work, the solution quality and computational efficiency still pose a challenge. This paper aims to address these two issues.
Scatter search (SS) and a cooperative co‐evolutionary architecture are integrated to form a new approach called a cooperative co‐evolutionary scatter search (CCSS). The cooperative co‐evolutionary architecture is characterized by the decomposition and cooperation for dealing with complex engineering problems. SS is a flexible meta‐heuristic method that can effectively solve the combinatorial optimization problems. Designing the elements of SS is context‐dependent. Considering the characteristics of SMLDP, our work focuses on two folds: the diversification method, and the reference set update method. The diversification method is built on the method of coordinate transformation and the controlled randomness. The reference set is updated by the static method on the basis of two dissimilarities. Two test problems for circles packing illustrated the capacity of SS. However, when solving SMLDP, SS shows some limitations in the computational time and quality. This study adopts divide‐conquer‐coordination strategy to decompose SMLDP into several layout sub‐problems. Then CCSS is applied to cooperatively solve these sub‐problems. The experimental results illustrate the capability of the proposed approach in tackling the complex problem with less computational effort.
Applying CCSS to SMLDP can obtain satisfying solutions in terms of quality and computational efficiency. This contrasts with the limiting experimental results of SMLDP with some approaches (including modified SS).
A new CCSS is proposed to provide an effective and efficient way of solving SMLDP. Some elements of SS are improved to address the layout problem. SMLDP is decomposed into several sub‐problems that can be solved cooperatively by CCSS after its characteristics are taken into consideration.
Purpose – Latino and African-American children and families in Washington, DC, face difficult circumstances, including high poverty, crime, and teenage pregnancy rates…
Purpose – Latino and African-American children and families in Washington, DC, face difficult circumstances, including high poverty, crime, and teenage pregnancy rates coupled with lower educational attainment. This chapter describes empirically supported approaches to positive development within and between the Latino and African-American communities, highlighting those utilized by CentroNía, a community-based, multicultural learning community in Washington, DC.
Approach – Community psychology promotes strength-focused, evidence-based practices shown to enrich child, family, neighborhood, and societal development among disenfranchised groups. This community psychology framework is used to examine CentroNía's work in support of the Latino and African-American communities of Washington, DC.
Findings – CentroNía espouses many of the tenets of community psychology. Its systematic efforts include the promotion of cultural unity and development, preventive interventions in early childhood and during the after-school hours, and context-enhancing practices at the family, school, and city levels.
Social implications – As the neighborhood of Columbia Heights becomes gentrified and the cost of living increases, Latino and African-American families find it increasingly difficult to remain in the community they have established together over the past 25 years. The consequences for low-income children, youth, and families, along with the evolution of CentroNía in this rapidly changing context, are discussed.
In 1987, Campbell Soup Company introduced the Souper Combo, a line of frozen soup and sandwiches. Melvin Druin, vice‐president for packaging, called it “the perfect combination of old‐fashioned good taste and today's convenience. No mess. No fuss. Easy to use. All you have to do is clean your spoon. Everything else just throw away.” Unfortunately, the multi‐layered plastic‐coated packaging does not just disappear when thrown away. Plastics packaging, particularly from convenience products, has become a waste disposal nightmare. Garbage, an environmental magazine, gave the Souper Combo an “in the dumpster” award, saying, “It's precisely the kind of product that's created the municipal landfill monster.”
America has a long history of environmental awareness which evolvedas the country grew and changed during the past 300 years. Today, anenvironmental concern by the people…
America has a long history of environmental awareness which evolved as the country grew and changed during the past 300 years. Today, an environmental concern by the people of the country is mainstream and therefore has become an integral part of corporate America. Explores the development, influence and direction of the US environmental movement. Provides background information to help understand why the marketplace is currently responding to the environmental stimulus. Looks at the marketing methods by which the country is expressing this environmental concern and traces the paths taken by those who first advocated the need for an environmental consciousness. Combines historical aspects of the American environmental movement with addressing the growing challenges facing the integration of business and environmental sensitivity.