5,629 research outputs found
XSECT: A computer code for generating fuselage cross sections - user's manual
A computer code, XSECT, has been developed to generate fuselage cross sections from a given area distribution and wing definition. The cross sections are generated to match the wing definition while conforming to the area requirement. An iterative procedure is used to generate each cross section. Fuselage area balancing may be included in this procedure if desired. The code is intended as an aid for engineers who must first design a wing under certain aerodynamic constraints and then design a fuselage for the wing such that the contraints remain satisfied. This report contains the information necessary for accessing and executing the code, which is written in FORTRAN to execute on the Cyber 170 series computers (NOS operating system) and produces graphical output for a Tektronix 4014 CRT. The LRC graphics software is used in combination with the interface between this software and the PLOT 10 software
Advanced communications payload for mobile applications
An advanced satellite payload is proposed for single hop linking of mobile terminals of all classes as well as Very Small Aperture Terminal's (VSAT's). It relies on an intensive use of communications on-board processing and beam hopping for efficient link design to maximize capacity and a large satellite antenna aperture and high satellite transmitter power to minimize the cost of the ground terminals. Intersatellite links are used to improve the link quality and for high capacity relay. Power budgets are presented for links between the satellite and mobile, VSAT, and hub terminals. Defeating the effects of shadowing and fading requires the use of differentially coherent demodulation, concatenated forward error correction coding, and interleaving, all on a single link basis
Plasma reactor development for methane decomposition to acetylene and hydrogen
High temperature plasma reactor development for methane decomposition to acetylene and hydroge
A relational approach to the development of expert diagnostic systems
The proposition that, given a structural and/or functional description of any real or abstract system, an expert system can be built based on this description is examined. First, a model is developed for a microprocessor-controlled end effector/sensor system using a modeling approach called a relational Knowledge-Base Machine (RKBM). Next, an explanation of how the end effector model could be used for the error diagnosis on the operational end effector is given and two versions of an error diagnosis algorithm based on the model are presented. Finally, areas of further research are described that are necessary before an expert system using this approach becomes a reality
Recommended from our members
Psychological distress after stroke and aphasia: the first six months
Objective: We explored the factors that predicted psychological distress in the first six months post stroke in a sample including people with aphasia.
Design: Prospective longitudinal observational study.
Setting and subjects: Participants with a first stroke from two acute stroke units were assessed while still in hospital (baseline) and at three and six months post stroke.
Main measures: Distress was assessed with the General Health Questionnaire-12. Other measures included: NIH Stroke Scale, Barthel Index, Frenchay Aphasia Screening Test, Frenchay Activities Index, MOS Social Support Scale and social network indicators. Logistic regression was used to identify predictors of distress at each stage post stroke; and to determine what baseline factors predicted distress at six months.
Results: Eighty-seven participants were able to self-report on measures used, of whom 32 (37%) had aphasia. 71 (82%) were seen at six months, including 11 (16%) with aphasia. Predictors of distress were: stroke severity at baseline; low social support at three months; and loneliness and low satisfaction with social network at six months. The baseline factors that predicted distress at six months were psychological distress, loneliness and low satisfaction with social network (Nagelkerke R2 = 0.49). Aphasia was not a predictor of distress at any time point. Yet, at three months post stroke 93% of those with aphasia experienced high distress, as opposed to 50% of those without aphasia (χ2 (1) = 8.61, P<0.01).
Conclusions: Factors contributing to distress after stroke vary across time. Loneliness and low satisfaction with one’s social network are particularly important and contribute to long-term psychological distress
Solving the time-dependent Schr\"odinger equation with absorbing boundary conditions and source terms in Mathematica 6.0
In recent decades a lot of research has been done on the numerical solution
of the time-dependent Schr\"odinger equation. On the one hand, some of the
proposed numerical methods do not need any kind of matrix inversion, but source
terms cannot be easily implemented into this schemes; on the other, some
methods involving matrix inversion can implement source terms in a natural way,
but are not easy to implement into some computational software programs widely
used by non-experts in programming (e.g. Mathematica). We present a simple
method to solve the time-dependent Schr\"odinger equation by using a standard
Crank-Nicholson method together with a Cayley's form for the finite-difference
representation of evolution operator. Here, such standard numerical scheme has
been simplified by inverting analytically the matrix of the evolution operator
in position representation. The analytical inversion of the N x N matrix let us
easily and fully implement the numerical method, with or without source terms,
into Mathematica or even into any numerical computing language or computational
software used for scientific computing.Comment: 15 pages, 7 figure
Intense physical activity is associated with cognitive performance in the elderly
Numerous studies have reported positive impacts of physical activity on cognitive function. However, the majority of these studies have utilised physical activity questionnaires or surveys, thus results may have been influenced by reporting biases. Through the objective measurement of routine levels of physical activity via actigraphy, we report a significant association between intensity, but not volume, of physical activity and cognitive functioning. A cohort of 217 participants (aged 60–89 years) wore an actigraphy unit for 7 consecutive days and underwent comprehensive neuropsychological assessment. The cohort was stratified into tertiles based on physical activity intensity. Compared with individuals in the lowest tertile of physical activity intensity, those in the highest tertile scored 9%, 9%, 6% and 21% higher on the digit span, digit symbol, Rey Complex Figure Test (RCFT) copy and Rey Figure Test 30-min recall test, respectively. Statistically, participants in the highest tertile of physical activity intensity performed significantly better on the following cognitive tasks: digit symbol, RCFT copy and verbal fluency test (all P<0.05). The results indicate that intensity rather than quantity of physical activity may be more important in the association between physical activity and cognitive function
Interactions of asbestos-activated macrophages with an experimental fibrosarcoma
Supernatants from in vivo asbestos-activated macrophages failed to show any cytostatic activity against a syngeneic fibrosarcoma cell line in vitro. UICC chrysotile-induced peritoneal exudate cells also failed to demonstrate any growth inhibitory effect on the same cells in Winn assays of tumor growth. Mixing UICC crocidolite with inoculated tumor cells resulted in a dose-dependent inhibition of tumor growth; this could, however, be explained by a direct cytostatic effect on the tumor cells of high doses of crocidolite, which was observed in vitro
- …