A Spatial and Temporal Analysis of Riparian Vegetation along Satus Creek on the Yakama Indian Reservation

Satus Creek provides critical habitat for the Yakima River Basin steelhead. A diverse community of riparian vegetation is important for healthy fish habitat; vegetation changes can affect shade, cover, channel structure, water quality, and food availability. The purpose of this thesis is to analyze and illustrate riparian vegetation change, both temporally and spatially, along three separate reaches of Satus Creek. A Geographic Information Systems approach was applied to assess the vegetation change by comparing plant species composition and density on 1949 and 1995 aerial photographs. The GIS approach allowed patterns and trends in the vegetation to be identified. In less than fifty years, a significant shift from woody to herbaceous species has occurred. Black cottonwood (Populus trichocarpa) population size has decreased and white alder (Alnus rhombifolia) population size has increased. This thesis links these and other vegetation patterns occurring along Satus Creek to land use practices in the watershed

Using signaling to aid computer program comprehension

Guidelines for using style to improve computer program comprehension have often been proposed without empirical testing. This thesis reports on the results of three controlled experiments that investigated ways program style may be used to aid comprehension of source code listings. Experiments 1 and 2 were conducted using advanced computer science students as subjects and short Pascal programs. Results showed that student programmers used meaningful identifier names as important sources of information during comprehension of short programs. A review of the literature showed the need for the thesis' proposed methodology for designing controlled experiments on program comprehension that produce results which generalize well to situations involving professional programmers working on real world tasks. This methodology was used to design Experiment 3. Text comprehension researchers have investigated the use of signaling, or the placement of non-content information, in a text in order to emphasize certain ideas and/or clarify the organization. Experiment 3 investigated the role of signaling in another domain, that of computer program source code listings. The experiment had professional programmers study a 913-line C program. Three types of signals were investigated: preview statements, headings, and typographic cueing. The major results were (a) meaningful module names served as headings in the source code listing and helped professional programmers understand and locate information in the program; (b) header comments, when written as preview statements, helped professional programmers understand and locate information in the program; (c) typographic cueing, designed to provide emphasis and segmentation cues, helped programmers understand the program; and (d) the effects of meaningful names, header comments, and typographic cueing were additive. No significant interactions of effects were observed. Based on these results, guidelines are proposed for ways programmers may use comments and module names in source code to act as signals that aid future readers. In addition, guidelines are suggested for adding typographic signaling to provide emphasis to the comments and names

Does signaling help professional programmers read and understand computer programs?

Signaling refers to the addition of non-content information to a text in order to emphasize certain ideas and/or clarify the organization. There is increased interest in using typographic signaling, such as boldface type, different font sizes and ruled lines, to format computer program source code listings. However, little evidence exists to show that this type of formatting makes programs easier to read and understand. The present study reports on a controlled experiment which investigated the effectiveness of typographic signaling, header comments before modules, and mnemonic module names as ways to aid comprehension. We found that while all three factors helped experienced programmers confirm hypotheses about a 913-line program, only the header comments and mnemonic names helped the programmers locate material in the program. We also found only modest improvements in comprehension when typographic signaling was used with header comments and mnemonic names

An investigation of procedure and variable names as beacons during program comprehension

Beacons are defined as sets of key features that typically indicate the presence of a particular data structure or operation. It has been claimed that programmers use them to help comprehend an unfamiliar program. However, despite their importance, beacons are not well-defined and very few have been identified. The present study investigated the importance of procedure and variable names as beacons during comprehension of short Pascal procedures. Ninety-six college seniors and graduate computer science students studied versions of a binary search and sorting procedures for one minute each and then provided a written description of the functions of each procedure. It was found that both meaningful procedure and variable names served as beacons to high-level comprehension. However, a strong code beacon, like the swap operation in a sorting routine, was found to be relied on more than the procedure name for high-level comprehension

AN EVALUATION OF MERCURY COOLED BREEDER REACTORS

Under the New Reactor Concepts Evaluation Program sponsored by the United States Atomic Energy Commission. Advanced Technology Laboratories (a Division of American Radiator & Standard Sanitary Corporation) has undertaken am investigation of the technical feasibility and economic potential of the use of boiling mercury as a coolant for fast breeder reactors The investigation was performed between January 1, 1959, and October 31. 1959. This is the final report on that investigation and is submitted in compliance with the terms of the program authorization, Contract Number AT(04-3)-109, Project Agreement Number 4. (auth

A parametric study on supercritical water gasification of Laminaria hyperborea: a carbohydrate-rich macroalga.

The potential of supercritical water gasification (SCWG) of macroalgae for hydrogen and methane production has been investigated in view of the growing interest in a future macroalgae biorefinery concept. The compositions of syngas from the catalytic SCWG of Laminaria hyperborea under varying parameters including catalyst loading, feed concentration, hold time and temperature have been investigated. Their effects on gas yields, gasification efficiency and energy recovery are presented. Results show that the carbon gasification efficiencies increased with reaction temperature, reaction hold time and catalyst loading but decreased with increasing feed concentrations. In addition, the selectivity towards hydrogen and/or methane production from the SCWG tests could be controlled by the combination of catalysts and varying reaction conditions. For instance, Ru/Al2O3 gave highest carbon conversion and highest methane yield of up to 11 mol/kg, whilst NaOH produced highest hydrogen yield of nearly 30 mol/kg under certain gasification conditions

Model and Design of a Fully-Integrated Bioregenerative Life Support System (FI-BLSS) Using Scalable Interactive Model of an Off-World Community (SIMOC)

The focus of human spaceflight is shifting from near Earth operations to making humanity a multi-planetary species. Bioregenerative life support systems (BLSS) capitalize on biological processes to provide food, water, and oxygen for the crew, manage wastes, and minimize reliance on consumables from Earth. BLSS that integrate multiple types of organisms into one interconnected system such as BIOS, MELiSSA, and the Lunar PALACE have seen some success but do not take full advantage of other types of organisms. To further BLSS design, a novel agent-based modeling program (Scalable Interactive Model of an Off-world Community, SIMOC) was enhanced for one of its first research applications and used to develop models of Fully-Integrated Bioregenerative Life Support Systems (FI-BLSS). Two novel agents representing mushroom and algae cultures were developed and programmed in SIMOC. These two agents were informed using experimental data collected on a Pleurotus ostreatus culture and an Arthrospira (Spirulina) platensis culture respectively. Three FI-BLSS models were developed showing that: (1) the oxygen concentration in a habitat with a crew of 4 could be maintained between 19.5% and 20% for 500 days; (2) the food requirements of a crew of 4 can be met by a FI-BLSS for 425 days after an initial 75 day growing period; and (3) incorporating a FI-BLSS within the habitat volume of the Space Analog for Moon and Mars (SAM) can reduce the use of physicochemical life support systems and injected oxygen usage by 21.3% . Limitations were noted with the data and modeling process, and comparing similar models shows the benefit of including algae and mushrooms as part of a FI-BLSS. Future enhancements can be made to SIMOC to further advance its research and educational capability. This would empower the use of SIMOC to design a FI-BLSS for construction within a sealed facility such as SAM and long duration human spaceflight missions

A Predictive Model for the Production Rates of a Bioregenerative Life Support System

Future long-term human space flight will require systems that are reliable, sustainable, and can continue to function for the entire length of the mission. Included in these possibilities are a relatively short two-year expedition to Mars as well as the indefinite colonization of another celestial body. Life support presents a significant challenge to this concept as many of the systems currently in use would require bringing a prohibitively heavy and bulky amount of supplies and consumables. An additional challenge is what to do with all the refuse from humans and other systems within the habitat. An innovative solution that addresses both of these problems is the use of bioregenerative life support (BLS). This type of life support utilizes the evolutionarily refined abilities of biological organisms to produce oxygen and sequester carbon dioxide through photosynthesis, purify water through transpiration, and produce edible biomass and calories for human consumption. In addition to being reliable, these systems operate at ambient conditions which reduces risk, and also provide psychological benefits to the crew. A successful BLS system will likely include many subsystems of which a higher plants production chamber will be one. The inclusion of biology as part of a life support system introduces complexity and mathematical models that can accurately predict the production rates of these systems is necessary. One such model that describes the production of a higher plants growth system is the Modified Energy Cascade Model (MEC) which was developed by James Cavazzoni in the early 2000’s. Around this model, a wrapper was developed to allow a user or system designer to input parameters for a hypothetical design and receive graphics depicting the production rates of said system over the entire course of the proposed mission for two different harvest strategies. This allows the user to accurately predict the production of any design and optimize to find the solution that best fits the needs of the mission. Four different BLS system example analogues were analyzed to show this utility and to allow for the further discussion of the design process surrounding such a system. This tool could also be modified to allow the design to identify deficiencies in the astronauts’ diets and show the effect of variable environmental conditions. In its current form, this tool would have the most potential benefit during the system and concept of operations (ConOps) design phases of a life support system for a long duration human space flight mission