Outsourcing with Heterogeneous Firms

A general framework for the study of outsourcing is introduced that incorporates dynamics and heterogeneity among both upstream and downstream producers to mimic an exit approach (Hirschman, 1970) to building vertical relations. The environment is one of search friction and incomplete contracts, where final-good producers require a specialized input and, upon matching with a supplier, can only contract the quantity of input. The results imply an assorted matching between producers and suppliers, so that more productive producers pair with more productive suppliers in the long run. It is shown that most efficient producers have some propensity to outsource, but only when there is a thick enough density of highly productive suppliers. Average employment in this model might increase or decrease with outsourcing, which is an observed pattern in the data. Some other diversities in plant-level behavior are also present in the results.Outsourcing; Productivity; Heterogeneity; Search Friction; Incomplete Contracts; Exit Strategy

Microwave Nondestructive Detection and Evaluation of Disbonding and Delamination in Layered-Dielectric Slabs

A microwave nondestructive technique for detection and evaluation of disbonding and delamination in layered-dielectric-slabs backed by a conducting plate is discussed. The theoretical development begins by considering an incident wave illuminating such a medium and then formulating the characteristics of the wave reflected by the metal plate. An effective reflection coefficient is determined in this way whose phase characteristics are used in the detection and evaluation of delaminations in the media. The characteristics of this phase as a function of several parameters such as delamination dielectric constant and thickness, slab dielectric constant, and thickness and the frequency of operation are investigated. The description of an experimental apparatus is given and it is used to perform several experiments to test and verify the theory. Very good agreement was obtained between the theoretical and experimental results

Productivity Dispersion, Plant Size, and Market Structure

Ample evidence from micro data suggests that productivity at establishment level is dominated by idiosyncratic factors. The productivity differences across establishments are very large and persistent even with the narrowest definition of industries. There is an attempt to identify sources of frictions that cause such productivity dispersion and negatively affect the average productivity of industries. This dissertation contemplates a non-monotonic relationship between productivity and input size and studies its importance in shaping the relationship between productivity dispersion and the producer size, a fact that is presented along with supportive empirical results. The role of market structure is then elaborated in creating the observed behavior. The US Census of Manufactures reveals significant productivity dispersion at any employment level. Moreover, this productivity dispersion falls with employment size within most manufacturing industries. This pattern is considerably strong for establishments in industries whose products are primarily locally traded. It will be shown that general approaches such as industry selection and simple statistical aggregation do not explain this pattern convincingly, while sector-specific factors such as market localization can mimic this behavior much more closely. Based on these results, a market structure model is introduced that uses demand size and market localization as constraining forces to generate a bell-shaped relationship between input size and productivity within a market and for locally traded goods. The non-monotonicity of the relationship is a clear departure from most economic models where input size of plants is monotonically increasing with their productivity in the long-run. Because of the bell-shaped relationship, the proposed model predicts significant long-run productivity dispersion at any level of input size. Also this dispersion decreases with input size, in the same way as is observed in the data. The model is calibrated and then simulated using data on Ready-Mix Concrete. First, the relationship between productivity and input size in the data is of a similar bell-shaped form. The effect of market size is also shown to be consistent with model predictions. Second, simulated results produce productivity dispersions that fall with input size with almost the same slope as observed in the data. This, in turn, suggests that the difference between simulated and actual productivity dispersions, summarizing the effect of other frictions, is almost uniform across sizes. Finally the robustness of the results is demonstrated through various tests. Throughout the discussion, a distinction is made between physical and revenue productivities and the theoretical implications of both measures are shown to be qualitatively the same

Multiproduct Multinationals and the Quality of Innovation

This research sheds light on the role of product scope on the innovation activity of multinational multi-product firms. We use patent citation data to break down innovation into two types by measuring the degree to which innovation performed by firms is fundamental and the extent to which the output of the R&D can be spread across different product lines. We focus on two features in multinational production: (i) fundamental innovation is geographically more difficult to transfer abroad to foreign production sites, (ii) learning spillovers can occur from international operations. The results reveal that the second effect is more likely to dominate when a firm is active in more product lines. We argue that a more diversified portfolio of products increases a firm’s scope of learning from international operations, thereby enhancing its ability to engage in more fundamental research. In contrast, firms with less product lines that geographically separate production from innovation shift the innovation activities towards more specialized types of innovation

Open-Ended Rectangular Waveguide for Nondestructive Thickness Measurement and Variation Detection of Lossy Dielectric Slabs Backed by a Conducting Plate

Solutions of fields inside a slab of a generally lossy dielectric medium backed by a conducting plate, placed outside a waveguide-fed rectangular aperture, are evoked in the application to the microwave nondestructive thickness measurement of such dielectric slabs. Upon construction of the waveguide terminating admittance expression from its variational form, an inverse problem is then solved to extract the slab thickness from the conductance and susceptance in a recursive manner. A comparison between the experimental and theoretical results showed that the significance of higher order modes is minimal; hence, the dominant mode assumption is, in general, valid to describe the aperture field distribution. The validity of this assumption has led to the construction of a simple integral solution which is fast converging for generally lossy dielectric slabs, and may easily be implemented for realtime applications. Experiments were conducted to verify the theoretical findings. Good agreement was obtained between the theoretical and experimental results. Multiple thicknesses of two different dielectric samples were estimated in this way

A Novel Numerical Technique for Dielectric Measurement of Generally Lossy Dielectrics

A method for determining the dielectric properties of infinite half-space of generally lossy dielectric materials is described. This method utilizes the measurement of the admittance of a rectangular waveguide radiating into such dielectrics. It is shown that the real part of the admittance is relatively insensitive to the variations of the imaginary part of the dielectric constant. Subsequently, a numerical procedure is initiated which provides a simple and fast-converging approach for calculating the dielectric properties. This numerical procedure lends itself to implementation by personal computers--a major advantage over the existing computational schemes. The theoretical formulation for the expression of the admittance of an open-ended waveguide and the numerical procedure are discussed in detail. Results of several measurements of freespace and lossy dielectric samples (rubber with carbon black) to verify the theory and the numerical scheme are given. The results give good agreement with other measurement schemes. Comments on the accuracy of the results are also provided

Analysis of Radiation from an Open-Ended Coaxial Line into Stratified Dielectrics

Radiation from an open-ended coaxial transmission line into an N-layer dielectric medium is studied in application to nondestructive evaluation of materials. Explicit formulations for two cases of layered media, one terminated into an infinite half-space and the other into a conducting sheet are addressed in general form. In the theoretical derivations it is assumed that only the fundamental TEM mode propagates inside the coaxial line. The terminating admittance of the line is then formulated using the continuity of the power flow across the aperture. The admittance expressions for specific cases of two-layer dielectric composite with generally lossy dielectric properties, and a two-layer composite backed by a conducting sheet are presented and inspected explicitly. The numerical results of the aperture admittance formulation are discussed and compared with the available infinite half-space model which had been experimentally verified

Microwave Noncontact Examination of Disbond and Thickness Variation in Stratified Composite Media

Numerical and experimental results of a microwave noncontact, nondestructive detection and evaluation of disbonds and thickness variations in stratified composite media are presented. The aperture admittance characteristics of a flange mounted rectangular waveguide radiating into a layered, generally lossy dielectric media backed or unbacked by a conducting sheet is modeled. The theoretical implementation is based on a Fourier transform boundary matching technique to construct the field components in each medium, coupled with a stationary form of the terminating aperture admittance of the waveguide. The model can serve as a reliable test bed for real-time examination of layered composite media. Experimental results for several cases are presented which show good agreement with the theoretical findings. This is a versatile technique for near-field in situ interrogation of stratified composite media which provides for high resolution measurements