Hasil untuk "Industry"

M. Porter

William . Gillette, Phyllis F. Field

The communication sector of an economy comprises a range of technologies, physical media, and institutions/rules that facilitate the storage of information through means other than a society's oral tradition and its transmission over distances beyond the normal reach of human conversation. This chapter provides data on the historical evolution of a disparate range of industries and institutions contributing to the movement and storage of information in the United States over the past two centuries. These include the U.S. postal service, the newspaper industry, book publishing, the telegraph, wired and cellular telephone service, radio and television, and the Internet.

C. C. Snow, L. G. Hrebiniak

G. Stigler

Birger Wernerfelt, Cynthia A. Montgomery

D. Audretsch

S. Besen, Joseph Farrell

J. Mata, P. Portugal

W. H. Thompson, Phillip B. Leege

W. K. Part, M. Ramli, C. Cheah

R. Florida

Andrew B. Bernard, J. Jensen, Peter K. Schott

S. Nadkarni, P. Barr

Mercedes Delgado, Michael E. Porter, Scott Stern

Clusters are geographic concentrations of industries related by knowledge, skills, inputs, demand, and/or other linkages. A growing body of empirical literature has shown the positive impact of clusters on regional and industry performance, including job creation, patenting, and new business formation. There is an increasing need for cluster-based data to support research, facilitate comparisons of clusters across regions, and support policymakers and practitioners in defining regional strategies. This paper develops a novel clustering algorithm that systematically generates and assesses sets of cluster definitions (i.e., groups of closely related industries). We implement the algorithm using 2009 data for U.S. industries (6-digit NAICS), and propose a new set of benchmark cluster definitions that incorporates measures of inter-industry linkages based on co-location patterns, input-output links, and similarities in labor occupations. We also illustrate the algorithm's ability to compare alternative sets of cluster definitions by evaluating our new set against existing sets in the literature. We find that our proposed set outperforms other methods in capturing a wide range of inter-industry linkages, including grouping industries within the same 3-digit NAICS.

O. Bandiera, Ian Richard Gordon, B. McCormick et al.

K. Brownell, K. Warner

Ľuboš Pástor, Rob Stambaugh, Lucian A. Taylor

Sunil Mithas, Ali Tafti, W. Mitchell

Giovanni Gavetti, Daniel A. Levinthal, Jan W. Rivkin

Xiaohui Yan, Shiqing Liu, Yongjian Su et al.

Free radicals are a class of reactive substances produced during the operation of proton exchange membrane fuel cells (PEMFCs), which have a great impact on the durability of PEMFCs. Previous research on the fuel cell degradation mechanism mainly focused on the degradation of the membrane electrode assembly (MEA) in high Pt loading PEMFCs, especially the chemical degradation of proton exchange membrane (PEM). However, there are significant differences in the characteristics and performance of PEMFCs with low and high Pt loading especially under the high current density, which is mainly due to the oxygen transport process in cathode catalyst layers (CCLs). Currently, few relevant research has explored the impact of chemical degradation on oxygen transport in the cathode of low-Pt PEMFCs. Therefore, this work investigates the effects of free radical attack on the structure of ionomer films, the local oxygen transport process and the evolution of the ionomer coated Pt/C structure in CCLs through physicochemical characterizations, electrochemical measurements and molecular dynamic simulations. Our research found that free radical attacks decreased the electrochemical active area of CCLs, but it also temporarily improved the cell performance at high current densities. Furthermore, molecular dynamics simulations demonstrated that the ionomer exhibited higher oxygen self-diffusion and a more relaxed structure after degradation.