EC72-1226 Growing Vegetable Transplants

Extension circular 72-1226 shows how to grow vegetable transplants

Pulse-Echo Harmonic Generation Measurements for Non-destructive Evaluation

Ultrasonic harmonic generation measurements have shown great potential for detecting nonlinear changes in various materials. Despite this, the practical implementation of the technique in non-destructive evaluation (NDE) has typically been limited to the through transmission setup case, with which problems arise in certain situations. Recently, works in the fields of nonlinear fluids and biomedical imaging have reported different application of the harmonic generation theory by making use of reflective boundaries and beam focusing. It is thought that such techniques may be similarly applied in the field of NDE to enable single-sided nonlinear inspection of components. In this paper, we initially describe a numerical model which has been used to determine the effects of attenuation and acoustic beam diffraction on measurements of the nonlinear parameter beta. We then extend the model to incorporate first the effects of multiple reflecting boundaries in the propagation medium, then of focused source excitation. Simulations, supported by experimental data, show that nonlinear pulse-echo measurements have the potential to provide a viable (and practical) alternative to the usual through-transmission type as a means of measuring beta in solids. Furthermore, it is shown that such measurements may be optimised, both by adjusting the excitation frequency, and by focusing the acoustic source at a certain point relative to the specimen boundary.</p

EC73-1229 Growing and Harvesting the Cole Crops.....Broccoli, Brussels Sprouts, Cabbage, Cauliflower, Kohlrabi

Extension circular 73-1229 is about growing and harvesting the cole crops like broccoli, Brussels sprouts, cabbage, cauliflower, and kohlrabi

Growing Degree Days Predictions for Corn and Sorghum Development and Some Applications to Crop Production in Nebraska

The concept of growing degree days (GDD) originated with observations by Reamur (1735) that plant development is more closely related to the temperature accumulated to a given stage than with time alone. It was not until nearly 200 years later, however, that Merriam (1894), Livingston (1916) and Klages (1942) began to use temperature accumulations in plant distribution studies and in crop geography. In the early 1950\u27s, a system involving growing degree days became widely used in the canning industry to schedule plantings and thus control time of harvest of rapidly maturing vegetables. This system provided a more precise control of both quantity and maturity of produce delivered for processing. It had a profound effect on processing efficiency and the cost and quality of canned vegetables, particularly peas and sweet corn. This study concerns GDD requirement for the series of consecutive phenological stages of field corn (Zea mays L.) and grain sorghum (Sorghum bicolor (L.) Moench) from emergence to physiological maturity. Such data are important for crop management decisions throughout the growing season

Simulation Studies of Corn Hybrid-Climate Response in Nebraska

Crop development models can be used to determine the expected phenological responses of corn hybrids to different planting dates and locations. The number of days from planting to maturity for a particular hybrid varies considerably between different dates of planting at a single location and between locations at the same planting date

An optimized tuned mass damper/harvester device

Much work has been conducted on vibration absorbers, such as tuned mass dampers (TMD), where significant energy is extracted from a structure. Traditionally, this energy is dissipated through the devices as heat. In this paper, the concept of recovering some of this energy electrically and reuse it for structural control or health monitoring is investigated. The energy-dissipating damper of a TMD is replaced with an electromagnetic device in order to transform mechanical vibration into electrical energy. That gives the possibility of controlled damping force whilst generating useful electrical energy. Both analytical and experimental results from an adaptive and a semi-active tuned mass damper/harvester are presented. The obtained results suggest that sufficient energy might be harvested for the device to tune itself to optimise vibration suppression

CROPSTATUS--A Computer Program to Assess the Effects of Seasonal Weather Changes on Nebraska\u27s Agriculture

CROPSTATUS is a series of programs residing in Nebraska\u27s AGNET system using daily weather data to assess seasonal changes in crops, livestock, and other agricultural conditions. Assessments are based on parameters developed from accumulations of current daily temperature and precipitation data collected from a network of synoptic, climate, and automated micrometeorological stations in Nebraska in comparison with daily normals. The daily normals were derived from monthly summaries using multiple regression models to compute daily values as a function of Julian day numbers. Crop phenology models based on growing degree days were used to monitor and forecast the progress of different crop strains and times of planting. Biological time scale statistical yield models are used for production estimates. Weather probability information is also available from CROPSTATUS. Long term climatic records have been used to determine spring and autumn freeze probabilities, preseason precipitation available for subsoil moisture recharge and the probabilities of weekly averages of daily maximum and minimum temperatures. These and other features are available in a menu of over 20 different agricultural weather information items developed from a network of 60 weather stations. CROPSTATUS is also used to prepare tabular data and computer maps showing changes in conditions throughout the state. These maps are used in meetings by an interdisciplinary committee of agricultural extension specialists to prepare weekly agweather situation/advisory reports

CROPSTATUS--A Computer Program to Assess the Effects of Seasonal Weather Changes on Nebraska\u27s Agriculture

CROPSTATUS is a series of programs residing in Nebraska\u27s AGNET system using daily weather data to assess seasonal changes in crops, livestock, and other agricultural conditions. Assessments are based on parameters developed from accumulations of current daily temperature and precipitation data collected from a network of synoptic, climate, and automated micrometeorological stations in Nebraska in comparison with daily normals. The daily normals were derived from monthly summaries using multiple regression models to compute daily values as a function of Julian day numbers. Crop phenology models based on growing degree days were used to monitor and forecast the progress of different crop strains and times of planting. Biological time scale statistical yield models are used for production estimates. Weather probability information is also available from CROPSTATUS. Long term climatic records have been used to determine spring and autumn freeze probabilities, preseason precipitation available for subsoil moisture recharge and the probabilities of weekly averages of daily maximum and minimum temperatures. These and other features are available in a menu of over 20 different agricultural weather information items developed from a network of 60 weather stations. CROPSTATUS is also used to prepare tabular data and computer maps showing changes in conditions throughout the state. These maps are used in meetings by an interdisciplinary committee of agricultural extension specialists to prepare weekly agweather situation/advisory reports

Substructurability:The effect of interface location on a real-time dynamic substructuring test

A full-scale experimental test for large and complex structures is not always achievable. This can be due to many reasons, the most prominent one being the size limitations of the test. Real-time dynamic substructuring is a hybrid testing method where part of the system is modelled numerically and the rest of the system is kept as the physical test specimen. The numerical–physical parts are connected via actuators and sensors and the interface is controlled by advanced algorithms to ensure that the tested structure replicates the emulated system with sufficient accuracy. The main challenge in such a test is to overcome the dynamic effects of the actuator and associated controller, that inevitably introduce delay into the substructured system which, in turn, can destabilize the experiment. To date, most research concentrates on developing control strategies for stable recreation of the full system when the interface location is given a priori. Therefore, substructurability is mostly studied in terms of control. Here, we consider the interface location as a parameter and study its effect on the stability of the system in the presence of delay due to actuator dynamics and define substructurability as the system’s tolerance to delay in terms of the different interface locations. It is shown that the interface location has a major effect on the tolerable delays in an experiment and, therefore, careful selection of it is necessary