Effect of layering pattern on dynamic mechanical properties of randomly oriented short banana/sisal hybrid fiber–reinforced polyester composites

Dynamic mechanical test methods have been widely employed for investigating the structures and viscoelastic behavior of polymeric materials to determine their relevant stiffness and damping characteristics for various applications. Randomly oriented short banana/sisal hybrid fiber–reinforced polyester composites were prepared by keeping the volume ratio of banana and sisal 1 : 1 and the total fiber loading 0.40 volume fraction. Bilayer (banana/sisal), trilayer (banana/sisal/banana and sisal/banana/sisal), and intimate mix composites were prepared. The effect of layering pattern on storage modulus (E′), damping behavior (tan δ), and loss modulus (E″) was studied as a function of temperature and frequency. Bilayer composite showed high damping property while intimately mixed and banana/sisal/banana composites showed increased stiffness compared to the other pattern. The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites. The activation energy of the intimately mixed composite was found to be the highest. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2168–2174, 2005     

Intertemporal and interspatial productivity differentials in U.S. manufacturing

This study analyzes the role productivity plays in explaining the variation in regional manufacturing growth rates. Using the neoclassical growth accounting procedure, we measure productivity from an intertemporal and interspatial perspective. Previous regional studies of U.S. manufacturing look only at the contribution of intertemporal productivity growth in explaning regional growth. These studies ignore the level of productivity and its effect on regional growth. For each year of our study, we rank regions by their interspatial productivity index. We find little difference between the productivity growth rates among the regions of the north and south. Differences among the regions emerge only when we consider interspatial productivity differentials. The North's level of factor productivity is 25 to 30% higher than the South's. The absolute productivity disadvantage of the South, however, is offset by its low input prices. Thus, it is the cost advantage of the South and not its productivity advantage that explains the region's relatively high growth rate.     

Family-based scheduling of shops with functional layouts

Simulation studies of job shop scheduling have typically assumed that either setup times are zero (subsumed within the processing time), or that every part has such a unique setup that no setup advantages can be gained by better scheduling policies. These studies also assume that the shop has exactly one copy of every machine. Some researchers have proposed heuristics that explicitly consider setup times and parallel machines in the context of a one stage shop with static arrivals. In contrast, family-based scheduling centred around setup time reduction has been credited with achieving economic savings in batch production industries where GT is employed. We motivate this study by the case of an existing realworld semi-conductor testing facility that has family setups, parallel machines and dynamic job arrival. Using this setting, we investigate whether benefits can still be obtained by using a family-based scheduling philosophy in those environments which do not permit the physical creation of cellular layouts due to the presence of process related or other constraints. We propose and evaluate two new dispatching procedures in a functional job shop that is modelled after the semiconductor testing facility. Results show that a family-based scheduling philosophy centred around coordinating machine setups is advantageous at relatively high setup to processing time ratios, while classic job shop rules suffice otherwise. Based on these results, we present recommendations for managing such environments. We also suggest future research directions in this area.     

Thermodynamic properties of 2,2,4-trimethylpentane

p, V, T data for 2,2,4-trimethylpentane (TMP) have been obtained in the form of volume ratios for six temperatures in the range 278.15 to 338.15 K for pressures up to 280 MPa. Isothermal compressibilities, isobaric expansivities, and internal pressures have been evaluated from the volumetric data. There are strong indications that the combination of the present results with literature data at 348 and 373 K enable accurate extrapolations in the liquid range up to 473 K, and possibly to as low as 170 K, for pressures up to 980 MPa; use of only the present results with the requirement that the B coefficient of the Tait equation should become equal to the negative of the critical pressure at the critical temperature provides interpolations and extrapolations of comparable accuracy. It is suggested that 2,2,4-trimethylpentane is a suitable secondary reference material (because of its large liquid range at atmospheric pressure and the similarity of its volumetric properties to a wide range of fluids) for calibration of measuring cells used for determining volumes of fluids under pressure.     

Two-dimensional specification of universal quantification in agraphical database query language

A technique is proposed for specifying universal quantification and existential quantification (combined with negation) in a two-dimensional (graphical) database query language. Unlike other approaches that provide set operators to simulate universal quantification, this technique allows a direct representation of universal quantification. Syntactic constructs for specifying universal and existential quantifications, two-dimensional translation of universal quantification to existential quantification (with negation), and translation of existentially quantified two-dimensional queries to relational queries are presented. The resulting relational queries can be processed directly by many existing database systems. The authors claim that this technique renders universal quantifications easy to understand. To substantiate this claim, they provide a simple, easy-to-follow guideline for constructing universally quantified queries     

Effects of physical confinement (< 125 nm) on the curing behavior of phenolic resin

How the physical confinement of phenolic resin in nano porous silica (8 nm ≤ pore diameter (D_p) ≤ 125 nm) affected the polymer's curing behavior was examined by conducting differential scanning calorimetry experiments at 320 K ≤ T ≤500 K. Our results suggested that upon incorporating the phenolic resin into the silica, its curing temperature was lowered. However, what was interesting was that there was an inverse linear dependence between the pore size and the curing temperature, i.e., the smaller the pore diameter the higher the curing temperature. There was evidence that phenolic resin was unable to penetrate into 8 nm‐sized pores. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

An entity-relationship programming language

The syntax for an integrated E-R programming language is presented. The problems that arise when a query language is embedded in a general-purpose programming language are discussed. Other E-R languages are also discussed. The requirements for the language and a syntax for an E-R model in which entity sets are mutually disjoint and each entity type has a unique, perhaps multiattribute, key are presented. The syntax for a more limited model restricted to binary relationships between entity types and without attributes is presented. Some implementation considerations are discussed