Further studies of methods for reducing community noise around airports

A simplified method of analysis was used in which all flights at a 'simulated' airport were assumed to operate from one runway in a single direction. For this simulated airport, contours of noise exposure forecast were obtained and evaluated. A flight schedule of the simulated airport which is representative of the 23 major U. S. airports was used. The effect of banning night-time operations by four-engine, narrow-body aircraft in combination with other noise reduction options was studied. The reductions in noise which would occur of two- and three-engine, narrow-body aircraft equipped with a refanned engine was examined. A detailed comparison of the effects of engine cutback on takeoff versus the effects of retrofitting quiet nacelles for narrow-body aircraft was also examined. A method of presenting the effects of various noise reduction options was treated

Morphology of Polyanhydride Microsphere Delivery Systems

Scanning electron microscopy (SEM) was used to elucidate the mechanism of polymer degradation and drug release in polyanhydride microspheres. Three different fabrication methods — solvent removal, solvent evaporation, and hot melt microencapsulation — were used to prepare polyanhydride microspheres containing a variety of drugs. The morphology of these microspheres releasing drug in vitro and in vivo was studied by SEM and compared with degradation and release data measured by conventional methods. Microspheres prepared by the three techniques were shown to have distinctive morphological characteristics induced by the nature of the fabrication method. In addition, SEM analysis could be used to explain the drug release profiles and polymer degradation behavior seen in vitro as well as the in vivo effects of insulin-loaded microspheres on diabetic rats. This study has shown SEM to be an important and powerful tool for analyzing the effects of microsphere fabrication method on drug release

Grown organic matter as a fuel raw material resource

An extensive search was made on biomass production from the standpoint of climatic zones, water, nutrients, costs and energy requirements for many species. No exotic species were uncovered that gave hope for a bonanza of biomass production under culture, location, and management markedly different from those of existing agricultural concepts. A simulation analysis of biomass production was carried out for six species using conventional production methods, including their production costs and energy requirements. These estimates were compared with data on food, fiber, and feed production. The alternative possibility of using residues from food, feed, or lumber was evaluated. It was concluded that great doubt must be cast on the feasibility of producing grown organic matter for fuel, in competition with food, feed, or fiber. The feasibility of collecting residues may be nearer, but the competition for the residues for return to the soil or cellulosic production is formidable

Dynamic Mechanical Behavior of Black Cherry (Prunus Serotina EHRH.)

The dynamic mechanical properties of black cherry (Prunus serotina Ehrh.) have been investigated as a function of temperature at audio frequencies. Relaxation processes are evident near 200, 360, and 510 K. The process near 200 K was investigated as a function of initial moisture content (based on mass measurements prior to testing). At moisture contents greater than about 20%, the damping peak is centered near 185 K. This relaxation shifts with moisture content, and at moisture contents below 6%, the peak is centered near 225 K. The relaxation in the 360 K region is also associated with initial moisture content. For oven-dry black cherry specimens, the dynamic mechanical properties in the 360 K region are nearly temperature-independent. The relaxation near 510 K is believed to be associated with thermal degradation of wood constituents that are known to degrade in that temperature region

Validation of the Standardized and Simplified Cutting Bill

This research validated the framework for the standardized and simplified cutting bill presented in an earlier paper. The cutting bill validation was carried out in two ways. First, all 20 of the cutting bill's part groups were examined to determine if significant yield influences resulted from changing specific part sizes within the boundaries of a given part group. Second, five cutting bills from industrial operations were fit into the framework of the cutting bill, and the simulated yields from these industrial cutting bills were compared with the fitted cutting bills. Yield differences between the two were calculated and tested for significance. Tests revealed that the standardized and simplified cutting bill framework performed as designed. The maximum yield difference observed was 2% and the average less than 1%. Clustering the industrial cutting bill part requirements according to the cutting bill framework led to an average absolute yield deviation between the original cutting bills and the clustered cutting bills of 3.25%. These results show while cutting bill part-size requirements can be clustered into part groups, yield differences of a certain magnitude are introduced by so doing

Some Physical Properties of Birch Carbonized in A Nitrogen Atmosphere

The dynamic mechanical properties, mass loss, and shrinkage data of birch carbonized in a nitrogen atmosphere to different temperatures from 473 to 973 K have been investigated. The dynamic elastic modulus data decreased as the heat treatment temperatures approached 673 K. Major mass loss and shrinkage accompanied the decrease in the modulus data. Treatments at higher temperatures (> 673 K) produced substantially less additional mass loss and shrinkage but produced increased rigidity in the char. The internal friction behavior of the char was complex

The Influence of Cutting-Bill Requirements on Lumber Yield Using a Fractional-Factorial Design Part II. Correlation and Number of Part Sizes

Cutting-bill requirements, among other factors, influence the yield obtained when cutting lumber into parts. The first part of this 2-part series described how different cutting-bill part sizes, when added to an existing cutting-bill, affect lumber yield, and quantified these observations. To accomplish this, the study employed linear least squares estimation technique. This second paper again looks at the influence of cutting-bill requirements but establishes a measure of how preferable it is to have a given part size required by the cutting-bill. The influence of the number of different part sizes to be cut simultaneously on lumber yield is also investigated.Using rip-first rough mill simulation software and an orthogonal, 220-11 fractional-factorial design of resolution V, the correlation between lengths, widths, and 20 part sizes as defined by the Buehlmann cutting-bill with high yield was established. It was found that, as long as the quantity of small parts is limited, part sizes larger than the smallest size are more positively correlated with high yield. Furthermore, only 4 out of the 20 part sizes tested were identified with having a significant positive correlation with above average yield (65.09%), while 10 were found with a significant negative correlation and above average yield. With respect to the benefit of cutting varying numbers of part sizes simultaneously, this study showed that there is a positive correlation between yield and the number of different part sizes being cut. However, Duncan's test did not detect significant yield gains for instances when more than 11 part sizes are contained in the cutting-bill

Creating A Standardized and Simplified Cutting Bill Using Group Technology

From an analytical viewpoint, the relationship between rough mill cutting bill part requirements and lumber yield is highly complex. Part requirements can have almost any length, width, and quantity distribution within the boundaries set by physical limitations, such as maximum length and width of parts. This complexity makes it difficult to understand the specific relationship between cutting bill requirements and lumber yield, rendering the optimization of the lumber cutting process through improved cutting bill composition difficult.An approach is presented to decrease the complexity of cutting bills to allow for easier analysis and, ultimately, to optimize cutting bill compositions. Principles from clustering theory were employed to create a standardized way to describe cutting bills. Cutting bill part clusters are part groups within the cutting bill's total part size space, where all parts are reset to a given group's midpoint. Statistical testing was used to determine a minimum resolution part group matrix that had no significant influence on yield compared to an actual cutting bill.Iterative search led to a cutting bill part group matrix that encompasses five groups in length and four groups in width, forming a 20-part group matrix. The lengths of the individual part groups created vary widely, with the smallest group being only 5 inches in length, while the longest two groups were 25 inches long. Part group widths were less varied, ranging from 0.75 inches to 1.0 inch. The part group matrix approach allows parts to be clustered within given size ranges to one part group midpoint value without changing cut-up yield beyond set limits. This standardized cutting bill matrix will make the understanding of the complex cutting bill requirements-yield relationship easier in future studies

The Influence of Cutting-Bill Requirements on Lumber Yield Using a Fractional-Factorial Design Part I. Linearity and Least Squares

The importance of lumber yield on the financial success of secondary solid wood products manufacturers has been known for quite some time. Various efforts have been undertaken to improve yield, such as inclusion of character marks (defects) in parts, "cookie-cutting" of boards, improved optimization algorithms, or improved cut-up technologies. For a variety of reasons, the relationship between cutting-bill requirements and lumber yield has attracted limited attention. This is Part I of a 2-part examination of this relationship.The standardized and simplified Buehlmann cutting bill and the Forest Service's Romi-Rip lumber cut-up simulator were used in this study. An orthogonal, 220-11 fractional-factorial design of resolution V was used to determine the influence of different part sizes on lumber yield. All 20 part sizes contained in the cutting bill and 113 of a total of 190 unique secondary interactions were found to be significant variables in explaining the variability in observed yield. Parameter estimates for the part sizes and the secondary interactions were used to specify the average yield contribution of each variable. Parts 445 mm long and 64 mm wide were found to have the most positive influence on yield. Parts smaller than 445 by 64 mm (such as, for example 254 by 64 mm) had a less pronounced positive yield effect because their quantity requirement is relatively small in an average cutting bill. Thus, the quantity required is obtained quickly during the cut-up process. Parts with size 1842 by 108 mm, on the other hand, had the most negative influence on high yield. However, as further analysis showed, not only the individual parts required by a cutting bill, but also their interaction determines yield. In general, it was found that by adding a sufficiently large number of smaller parts to a cutting bill that required large parts, high levels of yield can be achieved