A noncontact measurement technique for the density and thermal expansion coefficient of solid and liquid materials

A noncontact measurement technique for the density and the thermal expansion coefficient of refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2–3 mm diam samples can be levitated, melted, and radiatively cooled in vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045–1565 °C. The result for the liquid phase density can be expressed by rho=8.848+(6.730×10^−4)×T (°C) g/cm^3 within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by beta=(9.419×10^−5) −(7.165×10^−9)×T (°C) K^−1 within 0.2% accuracy

Fermion Production in Strong Magnetic Field and its Astrophysical Implications

We calculate the effective potential of a strong magnetic field induced by fermions with anomalous magnetic moments which couple to the electromagnetic field in the form of the Pauli interaction. For a uniform magnetic field, we find the explicit form of the effective potential. It is found that the non-vanishing imaginary part develops for a magnetic field stronger than a critical field and has a quartic form which is quite different from the exponential form of the Schwinger process. We also consider a linear magnetic field configuration as an example of inhomogeneous magnetic fields. We find that the imaginary part of the effective potential is nonzero even below the critical field and shows an exponentially decreasing behavior with respect to the inverse of the magnetic field gradient, which is the non-perturbative characteristics analogous to the Schwinger process. These results imply the instability of the strong magnetic field to produce fermion pairs as a purely magnetic effect. The possible applications to the astrophysical phenomena with strong magnetic field are also discussed.Comment: 13 pages, 3 figure

USER INFORMATION SATISFACTION: TOWARD CONCEPTUAL CLARITY

User information satisfaction (UIS) has been generally recognized by management information systems (MIS) researchers as one of the more important indicators of success in designing and implementing MIS. However, the existence of various UIS measures using different definitions of UIS has resulted in the use of inconsistent theoretical constructs and an inability to interpret across studies. Using consumer satisfaction research as a reference theory, this paper develops a conceptual model of UIS to clarify the concept. In the model, UIS is considered a function of organizational factors and the discrepancy between expected information service quality and perceived information service quality. This discrepancy, in turn, is a result of a series of gaps which are related to the MIS development and information service delivery processes. The implications of this model for future research and practice are discussed

Production of Neutral Fermion in Linear Magnetic Field through Pauli Interaction

We calculate the production rate of neutral fermions in linear magnetic fields through the Pauli interaction. It is found that the production rate is exponentially decreasing function with respect to the inverse of the magnetic field gradient, which shows the non-perturbative characteristics analogous to the Schwinger process. It turns out that the production rate density depends on both the gradient and the strength of magnetic fields in 3+1 dimension. It is quite different from the result in 2+1 dimension, where the production rate depends only on the gradient of the magnetic fields, not on the strength of the magnetic fields. It is also found that the production of neutral fermions through the Pauli interaction is a magnetic effect whereas the production of charged particles through minimal coupling is an electric effect.Comment: 11 pages, 2 figure

The Power of Integrality: Linkages between Product Architecture, Innovation, and Industry Structure

A substantial literature stream suggests that many products are becoming more modular over time, and that this development is often associated with a change in industry structure towards higher degrees of specialization. These developments can have strong implications for an industry’s competition as the history of the PC industry illustrates. To add to our understanding of the linkages between product architecture, innovation, and industry structure we study an unusual case in which a firm – through decreasing its product modularity – turned its formerly competitive industry into a near-monopoly. Using this case study we explore how existing theories on modularity explain the observed phenomenon, and show that most consider in their analysis technological change in rather long-term dimensions, and tend to focus on efficiencyrelated arguments to explain the resulting forces on competition. Expanding on these theories we add three critical aspects to the theory construct that connects technological change and industry dynamics. First, we suggest re-integating as a new design operator to explain product architecture genesis. Second, we argue that a finer-grained analysis of the product architecture shows the existence of multiple linkages between product architecture and industry structure, and that these different linkages help explain the observed intra-industry heterogeneity across firms. Third, we propose that the firm boundary choice can also be a pre-condition of the origin of architectural innovation, not only an outcome of efficiency considerations

The impact of a firm’s make, pseudoâ make, or buy strategy on product performance

The bulk of the product architecture and makeâ buy choice literature deals with product architecture changes from integral to modular form. This development is often associated with a firm’s tendency to change from a make to a buy strategy. However, a few studies investigate the change of product architecture in the reverse direction â from modular to integral form â and the subsequent change in the firm sourcing decision from a buy to a make strategy. These studies hold to the presumption that a firm following a make strategy will outperform firms following a buy strategy in dealing with integral product architectures. Based on the knowledgeâ based view, we argue for the viability of a sourcing strategy between the pure make and buy strategies â a pseudoâ make strategy. We also argue that as product architecture changes from a modular to integral form, firms adopting this pseudoâ make strategy are likely to show better product performance than firms following a pure make or buy strategy due to the relative knowledge advantages of the pseudoâ make strategy in dealing with the integral product architecture. We examine the impact of the make/pseudoâ make/buy strategies on product performance in the U.S. bicycle derailleur and freewheel market from 1980 to 1992 and provide theoretical and managerial implications of our results. Our findings highlight an important distinction between the pseudoâ make and makeâ buy strategies that has not previously been fully appreciated in the extant literature, and as a result increases our understanding of why some firms do not switch strategies from a buy to a make strategy when product architecture changes from modular to integral form as previously expected.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146818/1/joom289.pd