9,146 research outputs found
Characteristics and Behavior of Guineafowl and Domesticated Chicken Hybrids
The description, behavior, and morphologic measurements are presented for two hybrid crosses of domesticated chicken and guineafowl. The ease at which gallinaceous birds hybridize might warrant a closer look at the classification system. Possibly the number of families in the superfamily Phasianoidea should be reduced as some other researchers suggest
Machine Design Experiments Using Gears to Foster Discovery Learning
Machine Design Experiments Using Gears to Foster Discovery Learning For the typical undergraduate engineering student the topic of gears is introduced and discussed in several courses. Early exposure may be in a physics course or in a first dynamics course,where gear pairs are presented as an idealized means to change speed ratios and torque ratios.They are used for mechanical advantage or to achieve desired speed, and the focus is usually on kinematics. Since gears have inertia they store kinetic energy and are part of the dynamic equations of motion of mechanisms and machines. For mechanical engineering students, gears are a core component studied in courses such as \u27kinematics and dynamics of mechanisms\u27 and \u27machine design\u27, where the nomenclature and design equations are developed for various types of gears. There may be exposure to real gears in a mechanical engineering laboratory; more often, students may see gears passed around in class and as part of demonstrations.In this paper we describe new experiments that were designed to provide mechanical engineering students with discovery learning experiences with gears and mechanical systems using gears.The suite of practical experiments presents students with a range of challenges that require them to analyze, measure, design, and fabricate gears. Activities in the experiments include: (1) Identifying gear types (spur, helical, bevel, etc.) and appropriate applications (automotive transmissions and differentials, drills, gear head motors). (2) Disassembling and re-assembling a kitchen mixer (with design and manufacturing questions related to its gears). (3) Disassembling and re-assembling an automotive HVAC baffle sub-assembly (with measurement of train ratios, and design and manufacturing questions related to its gears). (4) Designing the gear mechanism for driving the minute and hour hands of a gear clock given a known yet arbitrary drive speed. Fabricating the gears of the clock via rapid prototyping (3D printing), assembling the clock, and then testing the timing accuracy.In addition to reporting the details of the experiments, we share experiences of students and teaching assistants in their use and effectiveness. We provide insights into how well students became familiar with types and nomenclature of gears and understood the applicability of different gears to actual real-world problems. The intent of the experiments is to effectively enhance mechanical engineering students\u27 awareness of gears and expand their knowledge and confidence in the use of gears in machine and mechanism design
Human factors of flight-deck checklists: The normal checklist
Although the aircraft checklist has long been regarded as the foundation of pilot standardization and cockpit safety, it has escaped the scrutiny of the human factors profession. The improper use, or the non-use, of the normal checklist by flight crews is often cited as the probable cause or at least a contributing factor to aircraft accidents. An attempt is made to analyze the normal checklist, its functions, format, design, length, usage, and the limitations of the humans who must interact with it. The development of the checklist from the certification of a new model to its delivery and use by the customer are discussed. The influence of the government, particularly the FAA Principle Operations Inspector, the manufacturer's philosophy, the airline's culture, and the end user, the pilot, influence the ultimate design and usage of this device. The effects of airline mergers and acquisitions on checklist usage and design are noted. In addition, the interaction between production pressures and checklist usage and checklist management are addressed. Finally, a list of design guidelines for normal checklists is provided
Asymmetric Intellectual Property Rights Protection and North-South Welfare
We construct a model of dynamic endogenous product innovation and international trade, using it to calculate the welfare effects of lower intellectual property rights (IPR) protection in the non-innovating South than in the innovating North. We find that it is generally in the North’s interest to protect its innovating sector by an import embargo on IPR-offending goods from abroad. We explain the paradoxical outcome where the North gains from weaker IPR enforcement in the South through a decomposition of the dynamic welfare formula. Key features include the ability of lower Southern IPR protection to spur innovation of Northern goods and to make available greater resources for Northern production of current consumption goods. Maintaining Northern IPR standards can be in the South’s interests even though the South would favor lower uniform levels of IPR protection.Intellectual Property Rights; Innovation; Imitation; North; South; Welfare
Business Profitability and Social Profitability: Evaluating Industries with Externalities, The Case Casinos.
Casino gambling is a social issue, because in addition to the direct benefits to those who own and use casinos, positive and negative externalities are reaped and borne by those who do not gamble. To correctly assess the total economic impact of casinos, one must distinguish between business profitability and social profitability. This paper provides the most comprehensive framework for addressing the theoretical cost–benefit issues of casinos by grounding cost–benefit analysis on household utility. It also discusses the current state of knowledge about the estimates of both the positive and negative externalities generated by casinos. Lastly, it corrects many prevalent errors in the debate over the economics of casino gambling.casino, crime, gambling, social costs, externality
Diablo Canyon Power Plant site ecological study Quarterly Report No. 2; October 1 - December 31, 1973
During the period October 1 - December 31, 1973, Fall surveys of permanent subtidal stations were completed with one station being surveyed. We were unable to locate 3
subtidal stations.
Intertidal studies were initiated in November. A total of 12
random stations was surveyed.
Interviews were conducted with commercial abalone fishermen
working between Pt. Buchon to Pecho Rock. We continued to
monitor the sea otter herd foraging between Pt. Buchon and
Lion Rock.
Progress was achieved in the abalone temperature tolerance
studies when a successful spawning occurred. (20pp.
Species Composition and Diversity of Hawk Populations in Northeastern Arkansas
Species composition and diversity of hawk populations were analyzed for northeastern Arkansas by the use of roadside censuses conducted in September through April from 1974- 1977. Data from 10 years of Jonesboro Christmas Bird Counts were also analyzed. During the roadside survey 20,174 miles were driven and 1819 raptors were counted. Ten species were observed with the Red-tailed Hawk being most abundant followed by the Marsh Hawk and the American Kestrel. Eight species were recorded from the 10 years of Christmas Bird Counts. Annual breeding bird surveys and spot records turned up three additional species making a total of 14 species in 15 years of study. Although hawk populations fluctuate from year to year, the data do not reveal any downward trend in numbers in northeastern Arkansas. Large concentrations of hawks do not appear in this region of the state until after mid-September. Populations reach a peak in December after which they decline in January. A second peak is reached in February followed by a gradual decline such that in April the American Kestrel is the only species consistently seen from the roadside. After April only a few hawks remain to nest. Both Krider\u27s and melanistic Red-tails occur here but from a total of 864 Red-tailed Hawks observed only 26 Krider\u27s and 31 melanistic or Buteo iamaicensis harlanii were recorded
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