3,220 research outputs found
The Entrepreneurial State Goes to Europe
This article investigates state-level export programs in response to the emerging new economic and political regime of Europe 1992. Little related export promotion activity is found, even in states reputed to have the most active entrepreneurial policies. The authors conclude that states have few resources to invest in export promotion and are inappropriate jurisdictions around which to organize such policy, despite the much touted entrepreneurial state
Design of a compliant wheel for a miniature rover to be used on Mars
The Jet Propulsion Laboratory has identified the need for a compliant wheel for a miniature martian rover vehicle. This wheel must meet requirements of minimum mass, linear radial deflection, and reliability in cryogenic conditions over a five year lifespan. Additionally, axial and tangential deflections must be no more than 10 percent of the radial value. The team designed a wheel by use of finite element and dimensionless parameter analysis. Due to the complex geometry of the wheel, a finite element model describing its behavior was constructed to investigate different wheel configurations. Axial and tangential deflections were greatly reduced but did not meet design criteria. A composite material was selected for its high strength, toughness, fatigue resistance, and damping characteristics. The team chose a Kevlar fiber filled thermoplastic composite. This report is divided into four primary sections. First, the introduction section gives background information, defines the task, and discusses the scope and limitations of the project. Second, the alternative designs section introduces alternative design solutions, addresses advantages and disadvantages of each, and identifies the parameters used to determine the best design. Third, the design solution section introduces the methods used to evaluate the alternates, and gives a description of the design process used. Finally, the conclusion and recommendations section evaluates the wheel design, and offers recommendations pertaining to improvement of the design solution
Imprints of a Primordial Preferred Direction on the Microwave Background
Rotational invariance is a well-established feature of low-energy physics.
Violations of this symmetry must be extremely small today, but could have been
larger in earlier epochs. In this paper we examine the consequences of a small
breaking of rotational invariance during the inflationary era when the
primordial density fluctuations were generated. Assuming that a fixed-norm
vector picked out a preferred direction during the inflationary era, we explore
the imprint it would leave on the cosmic microwave background anisotropy, and
provide explicit formulas for the expected amplitudes of
the spherical-harmonic coefficients. We suggest that it is natural to expect
that the imprint on the primordial power spectrum of a preferred spatial
direction is approximately scale-invariant, and examine a simple model in which
this is true.Comment: 7 pages, no figures; v5: Corrections, as well as use of more standard
convention, in section I
Preparation of charge transfer salt/polymer composites, and characterisation by saturable absorption
This thesis describes the preparation of microcrystalline dispersions of a series of organic semiconductors (the alkali metal salts of tetracyanoquinodimethane) within a host polymer. The linear optical properties of these composites are found to be dependent on the method of preparation. Their third order nonlinear optical properties are then investigated by measurement of the intensity dependence of their transmision. Close to the low energy, local excitation band saturable absorption is observed. In the region of the charge transfer band reverse saturable absorption is observed. The results are discussed in terms of a two level model
A Case Of Social Entrepreneurship: Tackling Homelessness
Social entrepreneurship integrates the resourcefulness of traditional entrepreneurship with the compelling drive to mitigate social ills. The focus of this study is on one social entrepreneurial organization that has changed the lives of the poor and homeless in a large urban area. The case study describes the dilemma the organization faces in deciding whether to enter into a joint venture with another non-profit social service entity. The joint venture would increase the number of at-risk people it could serve but threatens to change the unique nature of its operation and could compromise the organization’s brand
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