Sectors May Use Multiple Technologies Simultaneously: The Rectangular Choice-of-Technology Model with Binding Factor Constraints (Revised)

We develop the rectangular choice-of-technology model with factor constraints, or RCOT, a linear programming input-output model for analysis of the economy of a single region. It allows for one or more sectors to operate more than one technology simultaneously, with the relatively lowest-cost one supplemented by others if it encounters a binding factor constraint. The RCOT model solves for sector outputs, goods prices that are set by the highest-cost technologies in use, and scarcity rents that correspond to binding factor constraints experienced by the lower-cost technologies. The model is motivated by the fact that mineral deposits of different qualities may be exploited simultaneously, as may primary and recycled sources for the same materials or irrigated and rainfed techniques for producing the same crop. RCOT generalizes Carter’s square choice-of-technology model, in particular adding the factor constraints that allow several alternatives to operate simultaneously. The Appendix gives a numerical example.

Sectors May Use Multiple Technologies Simultaneously - The Rectangular Choice-of-Technology Model with Binding Factor Constraints

We develop the rectangular choice-of-technology model with factor constraints, or RCOT, for analysis of the economy of a single region, or of multiple regions in the context of a model of the world economy. RCOT allows for one or more sectors to operate more than one technology simultaneously, using the relatively lowest-cost one first and adding another if and when the preceding one encounters a binding factor constraint. The model is motivated by the evident fact that oil wells and mineral deposits of different qualities may be exploited simultaneously, as may the use of both primary and recycled sources for the same materials. RCOT generalizes Carter’s choice-of-technology model, which allowed one of two choices to all sectors, for up to q choices and adds the factor constraints that allow several alternatives to operate simultaneously. The Appendix gives a numerical example.

Human Ecology: Industrial Ecology

Industrial Ecology aims to inform decision making about the environmental impacts of industrial production processes by tracking and analyzing resource use and flows of industrial products, consumer products and wastes. Quantifying the patterns of use of materials and energy in different societies is one area of research in Industrial Ecology. An extensive literature is devoted in particular to Material Flow Analysis (MFA), the collection of data describing the flows of specific materials from sources to sinks within some portion of the global industrial system. Industrial Ecologists are also concerned with the system-wide environmental impacts associated with products. Design for the Environment involves the design or redesign of specific products so as to reduce their impacts, while Life Cycle Analysis (LCA) quantifies resource use and emissions per unit of product from material extraction to the eventual disposal of the product. The LCA community has created a significant body of best-practice methods and shared data and increasingly incorporates their analyses within input-output models of entire economies to capture that portion of the impact that would otherwise be overlooked. Input-output models, often incorporating both MFA and LCA data, analyze the effects on the environment of alternative consumption and production decisions. Industrial Ecology makes use of this array of top-down and bottom-up approaches, all of which are grounded in its origins in the ecology of the industrial system.

Embodied Resource Flows and Product Flows: Combining the Absorbing Markov Chain with the Input-Output Model

We develop the absorbing Markov chain (AMC) for describing in detail the network of paths through an industrial system taken by an embodied resource from extraction through intermediate products and finally consumer products.  We refer to this as a resource-specific network. This work builds on a recent literature in industrial ecology that uses an AMC to quantify the number of times a resource passes through a recycling sector before ending up in a landfill.  Our objective is to incorporate into that analysis an input-output (IO) table so that the resource paths explicitly take account of the interdependence of sectors through their reliance on intermediate products.  This feature makes it possible to track multiple resources simultaneously and consistently and to represent both resources and products in mixed units. Hypothetical scenarios about technological changes and changes in consumer demand are analyzed using an IO model, and model solutions generate the AMC database. A numerical example is provided.  AMC analysis describes the resource-specific networks using matrices that are derived not from the Leontief inverse but from a generalized variant of the Ghosh inverse matrix.  The Leontief inverse and especially the Ghosh inverse (although often not identified as such) have been used extensively to analyze ecological systems, and this paper extends these approaches for use in studying material cycles in industrial systems.  Constructing the AMC formalizes the resource-specific network analysis and generalizes the content and interpretation of the Ghosh matrix.  Path-based analyses derived from AMC theory are discussed in relation to the set of techniques called Structural Path Analysis (SPA). The paper concludes by identifying the three most critical enhancements to the IO model needed for analyzing material cycles: the simultaneous incorporation of waste-processing sectors, stock and flow relationships, and international trade.  The idea is to implement an AMC after each model extension. The modeling framework is intended for analyses such as: tracking a resource extracted in one region to landfills in other regions, evaluating ways to intensify secondary recovery at key junctures in-between.  There are other ways, of course, to approach such an analysis, but the combination of an extended IO model and an AMC, representing both resources and products in mixed units, provides a comprehensive, systematic and standardized approach that includes many features that are valued in industrial ecology and builds directly on a number of active research programs.

Labour Market and Investment Effects of Remittances

This paper examines the relationship between remittances from interna- tional migration and imperfections in labour and capital markets. We use a search-matching model of the labour market to show that remittances can have two opposing effects on the labour market of the source country. First, they raise the utility of the unemployed members back home and, if a worker's bargaining power is low, this causes the unemployment rate to rise. Second, remittances available for investment will relax credit constraints encountered by firms. If the `investment effect' outweighs the `search income' effect, then remittances will reduce the unemployment rate. Our empirical analysis sug- gests that remittances have a small negative effect on unemployment, but a positive and significant effect on investment.migration, remittances, capital constraints.

The Nucleus of Comet 10P/Tempel 2 in 2013 and Consequences Regarding Its Rotational State: Early Science from the Discovery Channel Telescope

We present new lightcurve measurements of Comet 10P/Tempel 2 carried out with Lowell Observatory's Discovery Channel Telescope in early 2013 when the comet was at aphelion. These data represent some of the first science obtained with this new 4.3-m facility. With Tempel 2 having been observed to exhibit a small but ongoing spin-down in its rotation period for over two decades, our primary goals at this time were two-fold. First, to determine its current rotation period and compare it to that measured shortly after its most recent perihelion passage in 2010, and second, to disentangle the spin-down from synodic effects due to the solar day and the Earth's orbital motion and to determine the sense of rotation, i.e. prograde or retrograde. At our midpoint of 2013 Feb 24, the observed synodic period is 8.948+/-0.001 hr, exactly matching the predicted prograde rotation solution based on 2010 results, and yields a sidereal period of the identical value due to the solar and Earth synodic components just canceling out during the interval of the 2013 observations. The retrograde solution is ruled out because the associated sidereal periods in 2010 and 2013 are quite different even though we know that extremely little outgassing, needed to produce torques, occurred in this interval. With a definitive sense of rotation, the specific amounts of spin-down to the sidereal period could be assessed. The nominal values imply that the rate of spin-down has decreased over time, consistent with the secular drop in water production since 1988. Our data also exhibited an unexpectedly small lightcurve amplitude which appears to be associated with viewing from a large, negative sub-Earth latitude, and a lightcurve shape deviating from a simple sinusoid implying a highly irregularly shaped nucleus.Comment: Accepted by AJ; 12 pages of text (pre-print style), 3 tables, 2 figure

Dynamic transverse debondong of a single s-2 fiber

Fiber reinforced composites are becoming increasingly common due to their high strength to weight ratios as compared to more conventional materials. Along with this increased used comes the need to have a higher level of understanding of the material characteristics. Specifically, the interface between the fiber and matrix is of particular interest. Loss of adhesion at this interface, known as debonding, can greatly decrease material strength. There has been significant research into debdonding phenomena at low strain rates. However, there is still a need for further insight at higher strain rates. In addition, given the opacity of many epoxy resins, conventional imaging is often unable to record debonding events or is restricted to only transparent matrices. By integrating a Kolsky tension bar along with X-Ray Phase Contrast Imaging and a high speed camera, high strain rate debonding events of an opaque fiber reinforced composite are recorded and analyzed. Specifically, imaging of transverse debonding initiation and progression along with debonding loads are obtained in this researc