Meter for use in detecting tension in straps having predetermined elastic characteristics

A meter for detecting tension in elastic bodies, especially in fabric straps employed as tie down straps for stowed objects is presented. The meter is characterized by a pair of elongated arms coupled together for pivotal motion about a common axis in a common plane and a strap receiver located at adjacent ends of the arms for receiving and securing adjacent portions of the strap. The receivers are supported by the arms for motion along intersecting arcs, and motion detection means is located at the opposite ends of the arms for detecting the magnitude of the motion imparted to the receivers as the strap is placed in tension

Alternative Approaches to Weed Management

Herbicide technology and use have been the focus of weed management research for the past several decades. Herbicides are an important component of weed management and will remain so for years to come. However, there is increasing pressure to improve the efficiency of herbicide use and develop alternative control methods. Herbicides are used on over 95% of the com and soybean in the Com Belt because of the presence of weeds and the need to minimize their adverse economic impacts. Large inputs of herbicides and tillage are needed to control weeds because of the lack of knowledge of weed biology and ecology, continuous production of summer annual row crops, and the absence of control alternatives. Currently, weed science has few, if any, alternatives to herbicides and tillage that are both economically and environmentally desirable

Tillage Systems and Weed Population Dynamics

Conservation tillage (CT) has had more impact on weed control in row crop production than any other recent change in management practices. In conventional tillage systems, moldboard plowing and secondary tillage just before planting help crop seedlings get an equal start with weed seedlings. In CT systems, herbicides are used to substitute for some or all of this tillage

Constricted high enthalpy arc heater design and performance data, including calculations for a 10 MW design First interim technical report

Performance prediction and design analysis of constricted coaxial-flow arc air heaters for materials testing and atmospheric entry simulatio

Occurrence of common milkweed (Asclepias syriaca) in cropland and adjacent areas

Interest in the population dynamics and geographic distribution of common milkweed (Asclepias syriaca L.) has recently increased due to the importance of common milkweed in the life cycle of the monarch butterfly (Danaus plexippus). A survey of common milkweed occurrence in various habitats was conducted in Iowa in June and July of 1999. Common milkweed was found in 71% of the roadsides and approximately 50% of the corn (Zea mays L.) and soybean (Glycine max L. Merr.) fields. Corn and soybean fields had 85% fewer patches than roadsides. Conservation reserve program fields had the greatest average area infested. While common milkweed was frequently found in corn and soybean fields, average frequency and patch sizes were much greater in noncrop areas

Initial dates of weed emergence

Timing of weed emergence varies both from year to year and also across the state. The table provides information on the initial date of emergence of five early weed species at locations across Iowa. Giant ragweed, one of the earliest emerging summer annuals found in crop fields, initiated emergence in the last week of March or first week of April in both 1998 and 1999. At most locations giant foxtail began emergence about 4 weeks after giant ragweed, but at the SE (Crawfordsville) location there has been only a 2-week difference in initial emergence of these species

Throughput-optimal systolic arrays from recurrence equations

Many compute-bound software kernels have seen order-of-magnitude speedups on special-purpose accelerators built on specialized architectures such as field-programmable gate arrays (FPGAs). These architectures are particularly good at implementing dynamic programming algorithms that can be expressed as systems of recurrence equations, which in turn can be realized as systolic array designs. To efficiently find good realizations of an algorithm for a given hardware platform, we pursue software tools that can search the space of possible parallel array designs to optimize various design criteria. Most existing design tools in this area produce a design that is latency-space optimal. However, we instead wish to target applications that operate on a large collection of small inputs, e.g. a database of biological sequences. For such applications, overall throughput rather than latency per input is the most important measure of performance. In this work, we introduce a new procedure to optimize throughput of a systolic array subject to resource constraints, in this case the area and bandwidth constraints of an FPGA device. We show that the throughput of an array is dependent on the maximum number of lattice points executed by any processor in the array, which to a close approximation is determined solely by the array’s projection vector. We describe a bounded search process to find throughput-optimal projection vectors and a tool to perform automated design space exploration, discovering a range of array designs that are optimal for inputs of different sizes. We apply our techniques to the Nussinov RNA folding algorithm to generate multiple mappings of this algorithm into systolic arrays. By combining our library of designs with run-time reconfiguration of an FPGA device to dynamically switch among them, we predict significant speedup over a single, latency-space optimal array

Emergence Patterns of Annual Weeds of Corn and Soybean

A better understanding of weed biology is critical for the development of more efficient weed management systems. Improved information on weed biology will not allow us to eliminate the inputs currently used to manage weeds. However, it provides the foundation for the development of new strategies and more efficient techniques to use these tools, resulting in more reliable weed management systems that are cost-effective and pose less threat to the environment

Efficient Deadlock Avoidance for Streaming Computation with Filtering

In this report, we show that deadlock avoidance for streaming computations with filtering can be performed efficiently for a large class of DAG topologies. We first give efficient algorithms for dummy interval computation in series-parallel DAGs, then generalize our results to a larger graph family, the CS4DAGs, in which every undirected cycle has exactly one source and one sink. Our results show that, for a large set of application topologies that are both intuitively useful and formalizable, the streaming model with filtering can be implemented safely with reasonable compilation overhead