Design of a variable-focal-length optical system

Requirements to place an entire optical system with a variable focal length ranging from 20 to 200 cm within a overall length somewhat less than 100 cm placed severe restrictions on the design of a zoom lens suitable for use on a comet explorer. The requirements of a wavelength range of 0.4 to 1.0 microns produced even greater limitations on the possibilities for a design that included a catadioptric (using mirrors and glass) front and followed by a zooming refractive portion. Capabilities available commercial zoom lenses as well as patents of optical systems are reviewed. Preliminary designs of the refractive optics zoom lens and the catadioptric system are presented and evaluated. Of the two, the latter probably has the best chance of success, so long as the shortest focal lengths are not really needed

Planning, creating and documenting a NASTRAN finite element model of a modern helicopter

Mathematical models based on the finite element method of structural analysis as embodied in the NASTRAN computer code are widely used by the helicopter industry to calculate static internal loads and vibration of airframe structure. The internal loads are routinely used for sizing structural members. The vibration predictions are not yet relied on during design. NASA's Langley Research Center sponsored a program to conduct an application of the finite element method with emphasis on predicting structural vibration. The Army/Boeing CH-47D helicopter was used as the modeling subject. The objective was to engender the needed trust in vibration predictions using these models and establish a body of modeling guides which would enable confident future prediction of airframe vibration as part of the regular design process

Feasibility of using a knowledge-based system concept for in-flight primary flight display research

A study was conducted to determine the feasibility of using knowledge-based systems architectures for inflight research of primary flight display information management issues. The feasibility relied on the ability to integrate knowledge-based systems with existing onboard aircraft systems. And, given the hardware and software platforms available, the feasibility also depended on the ability to use interpreted LISP software with the real time operation of the primary flight display. In addition to evaluating these feasibility issues, the study determined whether the software engineering advantages of knowledge-based systems found for this application in the earlier workstation study extended to the inflight research environment. To study these issues, two integrated knowledge-based systems were designed to control the primary flight display according to pre-existing specifications of an ongoing primary flight display information management research effort. These two systems were implemented to assess the feasibility and software engineering issues listed. Flight test results were successful in showing the feasibility of using knowledge-based systems inflight with actual aircraft data

SOC-DS computer code provides tool for design evaluation of homogeneous two-material nuclear shield

SOC-DS Code /Shield Optimization Code-Direc Search/, selects a nuclear shield material of optimum volume, weight, or cost to meet the requirments of a given radiation dose rate or energy transmission constraint. It is applicable to evaluating neutron and gamma ray shields for all nuclear reactors

Traditional versus rule-based programming techniques: Application to the control of optional flight information

To the software design community, the concern over the costs associated with a program's execution time and implementation is great. It is always desirable, and sometimes imperative, that the proper programming technique is chosen which minimizes all costs for a given application or type of application. A study is described that compared cost-related factors associated with traditional programming techniques to rule-based programming techniques for a specific application. The results of this study favored the traditional approach regarding execution efficiency, but favored the rule-based approach regarding programmer productivity (implementation ease). Although this study examined a specific application, the results should be widely applicable

New anthropometric classification scheme of preoperative nutritional status in children: A retrospective observational cohort study

Objective: WHO uses anthropometric classification scheme of childhood acute and chronic malnutrition based on low body mass index (BMI) (\u27wasting\u27) and height for age (\u27stunting\u27), respectively. The goal of this study was to describe a novel two-axis nutritional classification scheme to (1) characterise nutritional profiles in children undergoing abdominal surgery and (2) characterise relationships between preoperative nutritional status and postoperative morbidity. Design: This was a retrospective observational cohort study. Setting: The setting was 50 hospitals caring for children in North America that participated in the American College of Surgeons National Surgical Quality Improvement Program Paediatric from 2011 to 2013. Participants: Children \u3e28 days who underwent major abdominal operations were identified. Interventions/main predictor: The cohort of children was divided into five nutritional profile groups based on both BMI and height for age Z-scores: (1) underweight/short, (2) underweight/tall, (3) overweight/short, (4) overweight/tall and (5) non-outliers (controls). Main outcome measures: Multiple variable logistic regressions were used to quantify the association between 30-day morbidity and nutritional profile groups while adjusting for procedure case mix, age and American Society of Anaesthesiologists class. Results: A total of 39 520 cases distributed as follows: underweight/short (656, 2.2%); underweight/tall (252, 0.8%); overweight/short (733, 2.4%) and overweight/tall (1534, 5.1%). Regression analyses revealed increased adjusted odds of composite morbidity (35%) and reintervention events (75%) in the underweight/short group, while overweight/short patients had increased adjusted odds of composite morbidity and healthcare-associated infections (43%), and reintervention events (79%) compared with controls. Conclusion: Stratification of preoperative nutritional status using a scheme incorporating both BMI and height for age is feasible. Further research is needed to validate this nutritional risk classification scheme for other surgical procedures in children

Aviation Safety Issues Database

The aviation safety issues database was instrumental in the refinement and substantiation of the National Aviation Safety Strategic Plan (NASSP). The issues database is a comprehensive set of issues from an extremely broad base of aviation functions, personnel, and vehicle categories, both nationally and internationally. Several aviation safety stakeholders such as the Commercial Aviation Safety Team (CAST) have already used the database. This broader interest was the genesis to making the database publically accessible and writing this report

Prevalence and severity of dental caries among American Indian and Alaska Native preschool children

Objectives: To describe the Indian Health Service (IHS) oral health surveillance system and the oral health status of American Indian and Alaska Native (AI/AN) children aged 1‐5 years. Methods: A stratified probability sample of IHS/tribal sites was selected. Children were screened by trained examiners at community‐based locations including medical clinics, Head Start, preschools, kindergarten, and Women, Infants, and Children (WIC). Data collection was limited to the primary dentition and included number of teeth present plus number of teeth with cavitated lesions, restorations, and extracted because of decay. Number of molars with sealants and urgency of need for dental care data were also obtained. Statistical analyses were performed with SAS (SAS Institute Inc., Cary, NC, USA). Sample weights were used to produce population estimates based on selection probabilities. Results: A total of 8,461 AI/AN children 12‐71 months of age were screened at 63 IHS/tribal sites, approximately 7 percent of the estimated IHS user population of the same age. Overall, 54 percent of the children had decay experience, 39 percent had untreated decay, 7 percent had primary molar sealants, 36 percent needed early or urgent dental care, and 6 percent needed urgent dental care. The mean of decayed, missing, or filled teeth was 3.5 (95 percent confidence interval, 3.1‐3.9). The prevalence of decay experience increased with age; 21 percent of 1‐year‐olds and 75 percent of 5‐year‐olds had a history of caries. When stratified by IHS area, there were substantial differences in the oral health of preschool children. Conclusions: The results confirm that in the United States, AI/AN children served by IHS/tribal programs are one of the racial/ethnic groups at highest risk of caries.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93514/1/j.1752-7325.2012.00331.x.pd

Performance requirements analysis for payload delivery from a space station

Operations conducted from a space station in low Earth orbit which have different constraints and opportunities than those conducted from direct Earth launch were examined. While a space station relieves many size and performance constraints on the space shuttle, the space station's inertial orbit has different launch window constraints from those associated with customary Earth launches which reflect upon upper stage capability. A performance requirements analysis was developed to provide a reference source of parametric data, and specific case solutions and upper stage sizing trade to assist potential space station users and space station and upper stage developers assess the impacts of a space station on missions of interest