Subsurface Irrigation Research in Arkansas

A pilot study conducted in 1963 indicated that (1) cotton yields could be increased by subirrigation, (2) drilled orifices were unsatisfactory because of internal plugging caused by burrs and drilling particles, and (3) operating pressures of 5 and 10 psi were excessive, and 5 psi probably should be considered as an upper-limit pressure. A greenhouse study of a subirrigation system indicated that 2 psi should, in general, for in-wall orifices, be considered as a lower-limit pressure when orifices are built into the pipe wall. The greenhouse study also indicated that a placement depth of 12 inches was preferable to 18 inches in terms of the amount of water required. Twelve inches was used as the depth of placement for the field subirrigation system. A device was developed for forming orifices with a hot needle. This method has advantages over the drilled orifices used in the pilot study in that the forming process does not produce loose particles to fall inside the pipe or burrs which remain attached to the inner edge of the orifice and later cause stoppage problems. This method also seems preferable to punched orifices which tend to become smaller with time due to rebound of the plastic

ECONOMIC IMPACTS OF LAND USE CHANGES FROM A RESTRICTED NITROGEN FERTILIZER STRATEGY

Land Economics/Use,

Development of tandem cells consisting of GaAs single crystal and CuInSe2/CdZnS polycrystalline thin films

The tandem cells consisting of GaAs single crystal and CuInSe2 polycrystalline thin films are being developed under the joint program of the Boeing Co. and Kopin Corp. to meet the increasing power needs for future spacecraft. The updated status of this program is presented along with experimental results such as cell performance, and radiation resistance. Other cell characteristics including the specific power of and the interconnect options for this tandem cell approach are also discussed

Improved Analysis of RANKING for Online Vertex-Weighted Bipartite Matching

In this paper, we consider the online vertex-weighted bipartite matching problem in the random arrival model. We consider the generalization of the RANKING algorithm for this problem introduced by Huang, Tang, Wu, and Zhang (TALG 2019), who show that their algorithm has a competitive ratio of 0.6534. We show that assumptions in their analysis can be weakened, allowing us to replace their derivation of a crucial function $g$ on the unit square with a linear program that computes the values of a best possible $g$ under these assumptions on a discretized unit square. We show that the discretization does not incur much error, and show computationally that we can obtain a competitive ratio of 0.6629. To compute the bound over our discretized unit square we use parallelization, and still needed two days of computing on a 64-core machine. Furthermore, by modifying our linear program somewhat, we can show computationally an upper bound on our approach of 0.6688; any further progress beyond this bound will require either further weakening in the assumptions of $g$ or a stronger analysis than that of Huang et al.Comment: 23 pages, 7 figure

Effective Training for Flight in Icing Conditions

The development of a piloted flight simulator called the Ice Contamination Effects Flight Training Device (ICEFTD) was recently completed. This device demonstrates the ability to accurately represent an iced airplane s flight characteristics and is utilized to train pilots in recognizing and recovering from aircraft handling anomalies that result from airframe ice formations. The ICEFTD was demonstrated at three recent short courses hosted by the University of Tennessee Space Institute. It was also demonstrated to a group of pilots at the National Test Pilot School. In total, eighty-four pilots and flight test engineers from industry and the regulatory community spent approximately one hour each in the ICEFTD to get a "hands on" lesson of an iced airplane s reduced performance and handling qualities. Additionally, pilot cues of impending upsets and recovery techniques were demonstrated. The purpose of this training was to help pilots understand how ice contamination affects aircraft handling so they may apply that knowledge to the operations of other aircraft undergoing testing and development. Participant feedback on the ICEFTD was very positive. Pilots stated that the simulation was very valuable, applicable to their occupations, and provided a safe way to explore the flight envelope. Feedback collected at each demonstration was also helpful to define additional improvements to the ICEFTD; many of which were then implemented in subsequent demonstrations

Sociological Variables Affecting Clinical Issues: A Comparison of Graduate Distance Education Sites

This study examined the differences between students residing in urban and rural areas while enrolled in a graduate practice methods course taught via two-way interactive television. A questionnaire was administered to sixty-six students which assessed sociodemographic characteristics, current practice topics, practice approaches, and diversity issues. Rural offcampus students were found to reside in significantly smaller communities than the urban-based university campus students, and viewed several clinical issues as having more relevance to their future practice. Further, on-campus students were significantly younger than their rural counterparts, were more ethnically diverse, and placed more emphasis on the relevance of course material to address ethnicity, physical disability, and religiosity. Qualitative findings revealed mat the university site was the most supportive of privatization. The applicability of urbanized course content across rural sites was discussed, and implications for clinical sociology were provided

Current Methods Modeling and Simulating Icing Effects on Aircraft Performance, Stability, Control

Icing alters the shape and surface characteristics of aircraft components, which results in altered aerodynamic forces and moments caused by air flow over those iced components. The typical effects of icing are increased drag, reduced stall angle of attack, and reduced maximum lift. In addition to the performance changes, icing can also affect control surface effectiveness, hinge moments, and damping. These effects result in altered aircraft stability and control and flying qualities. Over the past 80 years, methods have been developed to understand how icing affects performance, stability, and control. Emphasis has been on wind-tunnel testing of two-dimensional subscale airfoils with various ice shapes to understand their effect on the flowfield and ultimately the aerodynamics. This research has led to wind-tunnel testing of subscale complete aircraft models to identify the integrated effects of icing on the aircraft system in terms of performance, stability, and control. Data sets of this nature enable pilot-in-the-loop simulations to be performed for pilot training or engineering evaluation of system failure impacts or control system design

Joint Custody as a Parenting Alternative

Joint custody of children has been a recently accepted alternative to the traditional child custody/visitation orders that usually follow dissolution proceedings. In 1980, California became one of the first states to provide, by statute, a presumption in favor of an award of joint custody to the parents. The authors present the legislative history of this joint custody statute and synthesize the various views that have been expressed on the subject of joint custody. Also presented is a discussion of the legislative intent behind the statute and whether the current law is the most effective means of protecting the best interests of the child and of assuring minor children of frequent and continuing contact with both parents after a marital dissolution