The mathematical modeling of rapid solidification processing

The detailed formulation of and the results obtained from a continuum mechanics-based mathematical model of the planar flow melt spinning (PFMS) rapid solidification system are presented and discussed. The numerical algorithm proposed is capable of computing the cooling and freezing rates as well as the fluid flow and capillary phenomena which take place inside the molten puddle formed in the PFMS process. The FORTRAN listings of some of the most useful computer programs and a collection of appendices describing the basic equations used for the modeling are included

Multilevel modelling of mechanical properties of textile composites: ITOOL Project

The paper presents an overview of the multi-level modelling of textile composites in the ITOOL project, focusing on the models of textile reinforcements, which serve as a basis for micromechanical models of textile composites on the unit cell level. The modelling is performed using finite element analysis (FEA) or approximate methods (method of inclusions), which provide local stiffness and damage information to FEA of composite part on the macro-level

Complementarities between IT and Organizational Structure: The Role of Corporate Exploration and Exploitation

The decentralization of organizational decision authority has been shown to be complementary to Information Technology (IT) in prior research. We draw from the information processing view of organizations, the IT and de/centralization debate, and organizational learning theory to argue that IT payoffs can also be improved by greater centralization of decision authority, contingent on a firm’s corporate learning type. We argue that an exploratory learning type is best pursued with a decentralized organization design, while an exploitative learning type requires a centralized organization design. We hypothesize that under corporate exploration, IT payoffs are enhanced through greater decentralization, whereas under corporate exploitation, returns to IT are improved by greater centralization. Our study uses a novel multi‐source panel on the IT capital, the degree of de/centralization, and the performance of almost 260 German manufacturing firms. We estimate production functions to assess the contribution of combning IT with de/centralization to firmlevel productivity under different corporate learning types. Our results strongly support our hypotheses and hold up to a variety of robustness tests

Product–process matrix and complementarity approach

The relationship between different types of innovation is analysed from three different approaches. On the one hand, the distinctive view assumes that the determinants of each type of innovation are different and therefore there is no relationship between them. On the other hand, the integrative view considers that the different types of innovation are complementary. Finally, the product–process matrix framework suggests that the relationship between product innovation and process innovation is substitutive. Using data from Spain belonging to the Technological Innovation Panel (PITEC) for the years 2008, 2009, 2010, 2011 and 2012, we tested which of the three approaches is predominant. To perform the hypothesis test, we used the so-called complementarity approach. We find that there is no unique relation. The nature of the relationship depends on the types of innovation that interact. Our most significant finding is that the relationship between product innovation and process innovation is complementary. This finding contradicts the proposal of the product–process matrix framework. Consequently, the joint implementation of both types of innovation generates a greater impact on the performance of a company than the sum of their separate implementation

Estimating Demand for Cellular Phone Service Under Nonlinear Pricing

Cellular phone carriers typically offer complicated nonlinear tariffs. Consumers make a discrete choice among several rate plans. Each plan has a nonlinear price schedule, and price is usually lower for in-network calls. I present an empirical framework to estimate demand under such nonlinear pricing schemes by using parsimonious data and apply the estimation method to analyze the cellular phone service market in Taiwan. Based on the estimated model, I evaluate the impacts of termination-based pricing schemes on the market structure. While the existence of in-network discounts causes considerable tipping effects on market shares, the effects come primarily from reducing the average prices, not from the difference between in-network and off-network prices. There is no evidence showing that termination-based pricing by itself has significant effects on market structure

Description of a traffic bridge of the Cantabrian SpeedWay made of composite materials

6 páginas, 9 figuras.[ES] En julio del 2004 se ha finalizado un paso superior vehicular de 46 metros de luz en la Autovía del Cantábrico en el tramo Tamón (Carreño) - Otur (Luarca) en el sub-tramo Vegarrozadas-Soto del Barco, muy próximo al Aeropuerto de Asturias. La peculiaridad de esta obra es que su estructura resistente está formada íntegramente por materiales compuestos. Este paso superior ha sido el resultado del proyecto Iberoeka “Pumacom”, iniciado en el año 2003. Un aspecto fundamental en el desarrollo de esta obra ha sido la resolución de las vigas del puente,fabricadas en fibra de carbono/epoxi sobre un bloque de poliuretano. Otro de los desafíos de mayor interés desde el punto de vista de los materiales consistía en la unión entre las vigas en carbono/epoxi y poliuretano con el tablero realizado en hormigón con un armado muy ligero formado por barras de diámetro 16 mm separadas cada 20 cm. El material seleccionado para los conectores de ambos elementos estructurales fue un material compuesto de fibra de vidrio AR fabricado mediante pultrusión.[EN] In july 2004 a 46 metres length bridge was placed at the Cantábrico Highway between Tamón (Carreño) - Otur (Luarca) that place is located near Asturias airport. This particular bridge has been manufactured mainly with composite materials. This bridge is the final result of an Iberoeka “Pumacom” funded project launched at the beginning of 2003. An innovative issue was the beams of the structure totally manufactured with epoxy/carbon fibre laminated on polyurethane preforms. Another very interesting challenge considered in this project is the joint between longitudinal bridge beams and the supporting platform made of light mortar and steel rods. Joints and connectors were made of AR galls fiber pultruded profiles.Peer reviewe

Pricing Services Subject to Congestion: Charge Per-Use Fees or Sell Subscriptions?

Should a firm charge on a per-use basis or sell subscriptions when its service experiences congestion? Queueing-based models of pricing primarily focus on charging a fee per use for the service, in part because per-use pricing enables the firm to regulate congestion--raising the per-use price naturally reduces how frequently customers use a service. The firm has less control over usage with subscription pricing (by definition, with subscription pricing customers are not charged proportional to their actual usage), and this is a disadvantage when customers dislike congestion. However, we show that subscription pricing is more effective at earning revenue. Consequently, the firm may be better off with subscription pricing, even, surprisingly, when congestion is intuitively most problematic for the firm: e.g., as congestion becomes more disliked by consumers. We show that the absolute advantage of subscription pricing relative to per-use pricing can be substantial, whereas the potential advantage of per-use pricing is generally modest. Subscription pricing becomes relatively more attractive if consumers become more heterogeneous in their service rates (e.g., some know they are "heavy" users and others know they are "light" users) as long as capacity is fixed, the potential utilization is high, and the two segments have substantially different usage rates. Otherwise, heterogeneity in usage rates makes subscription pricing less attractive relative to per-use pricing. We conclude that subscription pricing can be effective even if congestion is relevant for the overall quality of a service.service operations, operations strategy, pricing and revenue management, game theory, queueing theory