Some materials in drainage ditches that have traditionally been referred to and studied as sediments may be soils. In this study, we described and characterized materials found within agricultural ditches at the University of Maryland Eastern Shore Research Farm (Princess Anne, MD). Sixty-nine profiles were described in 10 ditches ranging in length from 225 to 550 m. Particle size, pH, and organic C were analyzed on 21 representative profiles. The materials met the definition of a soil in that they supported rooted vegetation. Samples of initial parent material were not collected; however, evidence was observed that horizons had formed through pedogenic processes including organic matter humification and accumulation, structure formation, Fe oxidation and reduction, sulfuricization, sulfidization, translocation, and bioturbation. Ditch soils were generally A horizons formed in loamy alluvial sediments eroded from loess-derived topsoil over gravelly and sandy C horizons formed in Coastal Plain sediments. Soil structure was described in 75% of A horizons. Redoximorphic features were described in 41% of A and 63% of C horizons. Organic C ranged from 0.4 to 124 g kg −1 Monosulfidic black oozes were observed on some soil surfaces; geological sulfidic materials were observed at depth. Shallow ditches (<1.5 m) tended to have structure and a layer in the substratum with a bright matrix color. Deep ditches (1.5–4 m) tended to have high n value, structureless sola, and Fe-depleted subsoil horizons. The presence of plants and the operation of pedologic processes may significantly affect ditch ecosystems and environmental functions.

Agricultural drainage ditches serve as P transport pathways from fields to surface waters. Little is known about the spatial variation of P at the soil-water interface within ditch networks. We quantified the spatial variation of surficial (0-5 cm) soil P within vegetated agricultural ditches on a farm in Princess Anne, MD with an approximately 30-yr history of poultry litter application. Ditch soils from 10 ditches were sampled at 10-m intervals and analyzed for acid ammonium oxalate-extractable P, Fe, Al (P(ox), Fe(ox), Al(ox)), and pH. These variables were spatially autocorrelated. Oxalate-P (min = 135 mg kg(-1), max = 6919 mg kg(-1), mean = 700 mg kg(-1)) exhibited a high standard deviation across the study area (overall 580 mg kg(-1)) and within individual ditches (maximum 1383 mg kg(-1)). Several ditches contained distinct areas of high P(ox), which were associated with either point- or nonpoint-P sources. Phosphorus was correlated with Al(ox) or Fe(ox) within specific ditches. Across all ditches, Al(ox) (r = 0.80; p < 0.001) was better correlated with P(ox) than was Fe(ox) (r = 0.44; p < 0.001). The high level of spatial variation of soil P observed in this ditch network suggests that spatially distributed sampling may be necessary to target best management practices and to model P transport and fate in ditch networks.

The mineral and organic materials in drainage ditches, when stable, may form soils as defined as materials that can support rooted vegetation or form horizons through processes of soil formation. Vegetation in ditches increases sediment retention, Cycles nutrients. and promotes the development of soil structure. Soil-forming processes such as horizon formation, biogeochemical cycling, structure formation, and faunal activity may affect the environmental quality of a ditch and its role in mediating the quality of overlying waters. In ibis paper we provide an overview of soil formation and biogeochemical processes that operate in ditches and discuss the role that these processes have in the mitigation of nutrient and pollutant losses from agriculture. We propose that ditch soil formation is a function of climatic temperature regime, organisms, topography (including the topography of the ditch and the surrounding landscape). bathymetry flow regime, parent material, time, water column attributes, and catastrophic events. Management procedures that encourage ditch vegetation. such as targeted clean-outs and gradual inundation, may increase the stability and ecosystem services of ditch soils. Site assessment and modeling of ditches may be improved by integrating information about ditch soils.

Pedological processes such as gleization and organic matter accumulation may affect the vertical distribution of P within agricultural drainage ditch soils. The objective of this study was to assess the vertical distribution of P as a function of horizonation in ditch soils at the University of Maryland Eastern Shore Research Farm in Princess Anne, Maryland. Twenty-one profiles were sampled from 10 agricultural ditches ranging in length from 225 to 550 m. Horizon samples were analyzed for total P; water-extractable P; Mehlich-3 P; acid ammonium oxalate-extractable P, Fe, and Al (P ox, Fe ox, Al ox); pH; and organic C (n = 126). Total P ranged from 27 to 4882 mg kg(-1), P ox from 4 to 4631 mg kg(-1), Mehlich-3 P from 2 to 401 mg kg(-1), and water-extractable P from 0 to 17 mg kg(-1). Soil-forming processes that result in differences between horizons had a strong relationship with various P fractions and P sorption capacity. Fibric organic horizons at the ditch soil surface had the greatest mean P ox, Fe ox, and Al ox concentrations of any horizon class. Gleyed A horizons had a mean Fe ox concentrations 2.6 times lower than dark A horizons and were significantly lower in total P and P ox. Variation in P due to organic matter accumulation and gleization provide critical insight into short- and long-term dynamics of P in ditch soils and should be accounted for when applying ditch management practices.

This paper reports on a new generation of composites fabricated by placing a low modulus, lightweight matrix over multiple layers of a relatively stiff reinforcement. These remarkable concoctions called Strategically Tuned Absolutely Resilient Structures (STARS) are designed to store strain energy in the form of elastic deformation that can be released in a controlled fashion as work or kinetic energy. They are designed to resist reverse loadings created by bending and torsion and can be highly stressed and deformed to store large amounts of elastic strain energy. When the structural response is modified as the service loads are decreased, the stored energy can be released in a controlled fashion to do useful work.

This paper describes analytical methods that can be used to determine the deflections and stresses in highly compliant graphite-reinforced cementitious composites. It is demonstrated that the standard transform section method fails to provide accurate results when the elastic modulus ratio exceeds 20. So an alternate approach is formulated by using the rule of mixtures to determine a set of effective material properties for the composite. Tensile tests are conducted on composite samples to verify this approach; and, when the effective material properties are used to characterize the deflections of composite beams subjected to pure bending, an excellent agreement is obtained.

Butt weld joints are most commonly designed into pressure vessels by using weld material properties that are determined from a tensile test. These properties are provided to the stress analyst in the form of a stressvs strain diagram. Variations in properties through the thickness of the weld and along the width of the weld have been suspect but not explored because of inaccessibility and cost. The purpose of this study is to investigate analytical and computational methods used for analysis of multiple pass aluminum 2219-T87 butt welds. The weld specimens are analyzed using classical plasticity theory to provide a basis for modeling the inelastic properties in a finite element solution. The results of the analysis are compared to experimental data to determine the weld behavior and the accuracy of currently available numerical prediction methods.

A signal-processing software system is described which allows the simulation of systems described by block diagrams or signal-flow graphs. A high-level data-flow language describes the interconnection of the components. All configurations of interconnections are allowed, including those containing feedback. Component systems (blocks) are allowed to be multi-input, multi-output, and to be programmed in any language. Blocks are implemented as separate processes running under a UNIX2 operating system. Input and output signals are transferred between blocks via the UNIXpipe facility. Thedata type of a signal is arbitrary in the context of the compiler; within a component or system, signals and internal variables can be either floating point or fixed point. The compiler enforces strong or weak type checking of signals according to the characteristics of the blocks generating and receiving the signals. The invariance of the program to implementation data type is accomplished by the use of abstract data types. Fixed-point simulations having differing number of bits per signal and per internal variable in a block are supported. Special display software is used to allow any signal in the system to be displayed on any graphics device.