Naval Postgraduate School

Abstract: This article presents a cognitive model of empowerment. Here, empowerment is defined as increased intrinsic task motivation, and our subsequent model identifies four cognitions (task assessments) as the basis for worker empowerment: sense of impact, competence, meaningfulness, and choice. Adopting an interpretive perspective, we have used the model also to describe cognitive processes through which workers reach these conclusions. Central to the processes we describe are workers' interpretive styles and global beliefs. Both preliminary evidence for the model and general implications for research are discussed.

Abstract: The use of an alternative to the research strategies employed for the past 20 yrs and more to investigate leadership produced results which question the traditional models and open new avenues for empirical exploration. Approaching leadership as an exchange relationship which develops within the vertical dyad over time during role making activities, this longitudinal study found that the degree of latitude that a superior granted to a member to negotiate his role was predictive of subsequent behavior on the part of both superior and member. Contrary to traditional views of leadership, superiors typically employed both leadership and supervision techniques within their units. With a select subset of their members, superiors developed leadership exchanges (influence without authority), and with others, superiors developed only supervision relationships (influence based primarily upon authority). Some of the many implications of these findings are discussed.

Abstract: This paper discusses the effects of frequency offset on the performance of orthogonal frequency division multiplexing (OFDM) digital communications. The main problem with frequency offset is that it introduces interference among the multiplicity of carriers in the OFDM signal. It is shown, and confirmed by simulation, that to maintain signal-to-interference ratios of 20 dB or greater for the OFDM carriers, offset is limited to 4% or less of the intercarrier spacing. Next, the paper describes a technique to estimate frequency offset using a repeated data symbol. A maximum likelihood estimation (MLE) algorithm is derived and its performance computed and compared with simulation results. Since the intercarrier interference energy and signal energy both contribute coherently to the estimate, the algorithm generates extremely accurate estimates even when the offset is far too great to demodulate the data values. Also, the estimation error depends only on total symbol energy so it is insensitive to channel spreading and frequency selective fading. A strategy is described for initial acquisition in the event of uncertainty in the initial offset that exceeds 1/2 the carrier spacing, the limit of the MLE algorithm. >

Abstract: The current understanding of the fundamentals of recrystallization is summarized. This includes understanding the as-deformed state. Several aspects of recrystallization are described: nucleation and growth, the development of misorientation during deformation, continuous, dynamic, and geometric dynamic recrystallization, particle effects, and texture. This article is authored by the leading experts in these areas. The subjects are discussed individually and recommendations for further study are listed in the final section.

Abstract: The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km2 in the open equatorial Pacific Ocean with iron This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production Similar increases were found in a chlorophyll-rich plume down-stream of the Galapagos Islands, which was naturally enriched in iron These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean