The role for search frictions for output and inflation dynamics: A Bayesian assessment

A search-theoretic monetary DSGE model with capital and in¬ventory investment is estimated, and its implications on output and inflation dynamics are contrasted with those of standard flexible price monetary models: a cash-in-advance and a portfolio adjustment cost model. Model estimation and comparison is conducted in a Bayesian way in order to account for possible model misspecification. The search model can track inflation and output data better. It dominates the other models in the ability to predict the autocorrela¬tions of inflation, the contemporaneous correlation between output growth and inflation, and in the persistent (dis-)inflation process after a (technol¬ogy) monetary shock. It generates a hump-shaped but delayed output response to a monetary shock that matches the data better than the other models.Inflation and Output Dynamics, Business Cycle, Search-Theory of Money, Bayesian Estimation, Model Comparison.

Fire Retardancy of Vinyl Ester Nanocomposites: Synergy with Phosphorus-Based Fire Retardants

Vinyl ester (PVE) nanocomposites were prepared using both clay and polyhedral oligosilsesquioxanes (POSS) as the nano-dimensional material. From cone calorimetric data, it was shown that both POSS and clay affect the flammability of the nanocomposites to the same extent. To improve on the flame retardancy, the nanocomposites were combined with phosphorous-containing fire retardants (FRs) and the result compared to the benchmark halogen-containing system. The use of the cone calorimeter to investigate the fire properties of these nanocomposites showed a great reduction in peak heat release rate (PHRR) in the presence of phosphate and slight improvements in average mass loss rate (AMLR) while thermogravimetric analysis showed improvement in char yield in the presence of phosphate. Several different organically modified clays were used and they affected the flammability to different extents. The time that the resin and clay were mixed and the atmosphere in which the reaction was carried out do not have an effect on the flammability and thermal stability of the nanocomposites. The effect of curing temperature on the clay dispersion and flammability was also investigated

Formal modelling for Ada implementations: tasking Event-B

This paper describes a formal modelling approach, where Ada code is automatically generated from the modelling artefacts. We introduce an implementation-level specification, Tasking Event-B, which is an extension to Event-B. Event-B is a formal method, that can be used to model safety-, and business-critical systems. The work may be of interest to a section of the Ada community who are interested in applying formal modelling techniques in their development process, and automatically generating Ada code from the model. We describe a streamlined process, where the abstract modelling artefacts map easily to Ada language constructs. Initial modelling takes place at a high level of abstraction. We then use refinement, decomposition, and finally implementation-level annotations, to generate Ada code. We provide a brief introduction to Event-B, before illustrating the new approach using small examples taken from a larger case study

The role of search frictions for output and inflation dynamics: a Bayesian assessment

Search frictions in the goods market have proven to be a fruitful deviation from the fiction of a centralized Walrasian market providing a micro-foundation of the use of money as a medium of exchange. Moreover, persistent propagation of monetary shocks can arise in search-theoretic monetary models through the interaction of search-frictions in the goods and labor markets, and inventory holdings. Here, a search-theoretic monetary DSGE model with capital and inventory investment is estimated, and its implications on output and inflation dynamics are contrasted with those of standard flexible price monetary models: a cash-in-advance and a portfolio adjustment cost model. Model estimation and comparison is conducted in a Bayesian way in order to account for possible model misspecification. The search model can track inflation and output data better, as well as it dominates the other models in the ability to predict the autocorrelations of inflation and the persistent disinflation process after a technology shock. It generates a hump-shaped but not strong enough output response to a monetary shock. Current and near current correlations between output growth inflation are predicted well.

Polybutadiene modified clay and its nanocomposites

A butadiene-modified clay was prepared by ionic exchange between sodium montmorillonite and a butadiene surfactant; the butadiene surfactant was obtained from the reaction of vinylbenzyl chloride grafted polybutadiene with a tertiary amine. Nanocomposites of polystyrene, high impact polystyrene, acrylonitrile–butadiene–styrene terpolymer, poly(methyl methacrylate), polypropylene and polyethylene were prepared by melt blending this modified clay with the virgin polymers. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, cone calorimetry and the evaluation of mechanical properties. A morphological study of PBD-modified clay–polymer nanocomposites shows that all the composites are immiscible micro-composites. The consistency of the result from XRD and TEM with that of cone calorimetry indicates that the cone calorimeter must also be considered as another method to examine the bulk sample and infer if good dispersion of the clay in the polymer has been achieved. The mechanical properties of the nanocomposites prepared from different methods show that the mechanical properties are, in general, predictable based on the type of dispersion

Evaluation of shuttle solid rocket booster case materials. Corrosion and stress corrosion susceptibility of several high temperature materials

Candidate alloys for the Shuttle Solid Rocket Booster (SRB) case were tested under simulated service conditions to define subcritical flaw growth behavior under both sustained and cyclic loading conditions. The materials evaluated were D6AC and 18 Ni maraging steel, both heat treated to a nominal yield strength of 1380 MN/sq m (200 ksi). The sustained load tests were conducted by exposing precracked, stressed specimens of both alloys to alternate immersion in synthetic sea water. It was found that the corrosion and stress corrosion resistance of the 18 Ni maraging steel were superior to that of the D6AC steel under these test conditions. It was also found that austenitizing temperature had little influence on the threshold stress intensity of the D6AC. The cyclic tests were conducted by subjecting precracked surface-flawed specimens of both alloys to repeated load/thermal/environmental profiles which were selected to simulate the SRB missions. It was found that linear removal operations that involve heating to 589 K (600 F) cause a decrease in cyclic life of D6AC steel relative to those tests conducted with no thermal cycling

Synergy Between Nanocomposite Formation and Low Levels of Bromine on Fire Retardancy in Polystyrenes

An organically-modified clay has been prepared using ammonium salts which contain an oligomeric material consisting of vinylbenzyl chloride, styrene and dibromostyrene. The presence of dibromostyrene enhances the flame retardancy of polystyrene nanocomposites compared to both the virgin polymer and polystyrene nanocomposites prepared from non-halogen-containing organically-modified clays. The nanocomposites were prepared both by bulk polymerization and melt blending and they were evaluated by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry measurements. Bulk polymerization produced nanocomposites with reduced peak heat release rate, reduced total heat release and improved thermal stability. It is noteworthy that all these improvements were obtained with clay loading as low as 3% and bromine content less than 4%

The role of search frictions for output and inflation dynamics: a Bayesian assessment

Search frictions in the goods market have proven to be a fruitful deviation from the fiction of a centralized Walrasian market providing a micro-foundation of the use of money as a medium of exchange. Moreover, persistent propagation of monetary shocks can arise in search-theoretic monetary models through the interaction of search-frictions in the goods and labor markets, and inventory holdings. Here, a search-theoretic monetary DSGE model with capital and inventory investment is estimated, and its implications on output and inflation dynamics are contrasted with those of standard flexible price monetary models: a cash-in-advance and a portfolio adjustment cost model. Model estimation and comparison is conducted in a Bayesian way in order to account for possible model misspecification. The search model can track inflation and output data better, as well as it dominates the other models in the ability to predict the autocorrelations of inflation and the persistent disinflation process after a technology shock. It generates a hump-shaped but not strong enough output response to a monetary shock. Current and near current correlations between output growth inflation are predicted well