A method for static and dynamic load analysis of standard and modified spur gears

The mesh stiffness and dynamic load characteristics for several cases of the Normal Contract Ratio and High Contact ratio gearing. The considered contact ratios were grouped in the general range of 1.7,2.0, and 2.3. The HCR gearing is defined by contact ratios equal to or greater than 2.0. The HCR gearing is represented by a group of small pressure angle, fine pitch, and long addendum gearing

Conceptual design of a fixed-pitch wind turbine generator system rated at 400 kilowatts

The design and cost aspects of a fixed pitch, 400 kW Wind Turbine Generator (WTG) concept are presented. Improvements in reliability and cost reductions were achieved with fixed pitch operation and by incorporating recent advances in WTG technology. The specifications for this WTG concept were as follows: (1) A fixed pitch, continuous wooden rotor was to be provided by the Gougeon Bros. Co. (2) An 8 leg hyperboloid tower that showed promise as a low cost structure was to be used. (3) Only commercially available components and parts that could be easily fabricated were to be considered. (4) Design features deemed desirable based on recent NASA research efforts were to be incorporated. Detailed costs and weight estimates were prepared for the second machine and a wind farm of 12 WTG's. The calculated cost of energy for the fixed pitch, twelve unit windfarm is 11.5 cents/kW hr not including the cost of land and access roads. The study shows feasibility of fixed pitch, intermediate power WTG operation

Dynamics of early planetary gear trains

A method to analyze the static and dynamic loads in a planetary gear train was developed. A variable-variable mesh stiffness (VVMS) model was used to simulate the external and internal spur gear mesh behavior, and an equivalent conventional gear train concept was adapted for the dynamic studies. The analysis can be applied either involute or noninvolute spur gearing. By utilizing the equivalent gear train concept, the developed method may be extended for use for all types of epicyclic gearing. The method is incorporated into a computer program so that the static and dynamic behavior of individual components can be examined. Items considered in the analysis are: (1) static and dynamic load sharing among the planets; (2) floating or fixed Sun gear; (3) actual tooth geometry, including errors and modifications; (4) positioning errors of the planet gears; (5) torque variations due to noninvolute gear action. A mathematical model comprised of power source, load, and planetary transmission is used to determine the instantaneous loads to which the components are subjected. It considers fluctuating output torque, elastic behavior in the system, and loss of contact between gear teeth. The dynamic model has nine degrees of freedom resulting in a set of simultaneous second order differential equations with time varying coefficients, which are solved numerically. The computer program was used to determine the effect of manufacturing errors, damping and component stiffness, and transmitted load on dynamic behavior. It is indicated that this methodology offers the designer/analyst a comprehensive tool with which planetary drives may be quickly and effectively evaluated

A multi-purpose method for analysis of spur gear tooth loading

A large digitized approach was developed for the static and dynamic load analysis of spur gearing. An iterative procedure was used to calculate directly the "variable-variable" gear mesh stiffness as a function of transmitted load, gear tooth profile errors, gear tooth deflections and gear hub torsional deformation, and position of contacting profile points. The developed approach can be used to analyze the loads, Hertz stresses, and PV for the normal and high contrast ratio gearing, presently the modeling is limited to the condition that for a given gear all teeth have identical spacing and profiles (with or without surface imperfections). Certain types of simulated sinusoidal profile errors and pitting can cause interruptions of the gear mesh stiffness function and, thus, increase the dynamic loads in spur gearing. In addition, a finite element stress and mesh subprogram was developed for future introduction into the main program for calculating the gear tooth bending stresses under dynamic loads

Dynamic effects of internal spur gear drives

Static analysis, dynamic analysis, and computer programs are discussed. Spur gear formulae and involute profile development and deflection are also discussed

Nuclear pores as versatile reference standards for quantitative superresolution microscopy

Quantitative fluorescence and superresolution microscopy are often limited by insufficient data quality or artifacts. In this context, it is essential to have biologically relevant control samples to benchmark and optimize the quality of microscopes, labels and imaging conditions. Here, we exploit the stereotypic arrangement of proteins in the nuclear pore complex as in situ reference structures to characterize the performance of a variety of microscopy modalities. We created four genome edited cell lines in which we endogenously labeled the nucleoporin Nup96 with mEGFP, SNAP-tag, HaloTag or the photoconvertible fluorescent protein mMaple. We demonstrate their use (1) as three-dimensional resolution standards for calibration and quality control, (2) to quantify absolute labeling efficiencies and (3) as precise reference standards for molecular counting. These cell lines will enable the broader community to assess the quality of their microscopes and labels, and to perform quantitative, absolute measurements

What research agenda could be generated from the European General Practice Research Network concept of Multimorbidity in Family Practice?

This is the final version of the article. Available from the publisher via the DOI in this record.BACKGROUND: Multimorbidity is an intuitively appealing, yet challenging, concept for Family Medicine (FM). An EGPRN working group has published a comprehensive definition of the concept based on a systematic review of the literature which is closely linked to patient complexity and to the biopsychosocial model. This concept was identified by European Family Physicians (FPs) throughout Europe using 13 qualitative surveys. To further our understanding of the issues around multimorbidity, we needed to do innovative research to clarify this concept. The research question for this survey was: what research agenda could be generated for Family Medicine from the EGPRN concept of Multimorbidity? METHODS: Nominal group design with a purposive panel of experts in the field of multimorbidity. The nominal group worked through four phases: ideas generation phase, ideas recording phase, evaluation and analysis phase and a prioritization phase. RESULTS: Fifteen international experts participated. A research agenda was established, featuring 6 topics and 11 themes with their corresponding study designs. The highest priorities were given to the following topics: measuring multimorbidity and the impact of multimorbidity. In addition the experts stressed that the concept should be simplified. This would be best achieved by working in reverse: starting with the outcomes and working back to find the useful variables within the concept. CONCLUSION: The highest priority for future research on multimorbidity should be given to measuring multimorbidity and to simplifying the EGPRN model, using a pragmatic approach to determine the useful variables within the concept from its outcomes.The study had a Grant of 8000 Euros from the EGPRN

A study protocol for the evaluation of occupational mutagenic/carcinogenic risks in subjects exposed to antineoplastic drugs: a multicentric project

<p>Abstract</p> <p>Background</p> <p>Some industrial hygiene studies have assessed occupational exposure to antineoplastic drugs; other epidemiological investigations have detected various toxicological effects in exposure groups labeled with the job title. In no research has the same population been studied both environmentally and epidemiologically. The protocol of the epidemiological study presented here uses an integrated environmental and biological monitoring approach. The aim is to assess in hospital nurses preparing and/or administering therapy to cancer patients the current level of occupational exposure to antineoplastic drugs, DNA and chromosome damage as cancer predictive effects, and the association between the two.</p> <p>Methods/Design</p> <p>About 80 healthy non-smoking female nurses, who job it is to prepare or handle antineoplastic drugs, and a reference group of about 80 healthy non-smoking female nurses not occupationally exposed to chemicals will be examined simultaneously in a cross-sectional study. All the workers will be recruited from five hospitals in northern and central Italy after their informed consent has been obtained.</p> <p>Evaluation of surface contamination and dermal exposure to antineoplastic drugs will be assessed by determining cyclophosphamide on selected surfaces (wipes) and on the exposed nurses' clothes (pads). The concentration of unmetabolized cyclophosphamide as a biomarker of internal dose will be measured in end-shift urine samples from exposed nurses.</p> <p>Biomarkers of effect and susceptibility will be assessed in exposed and unexposed nurses: urinary concentration of 8-hydroxy-2-deoxyguanosine; DNA damage detected using the single-cell microgel electrophoresis (comet) assay in peripheral white blood cells; micronuclei and chromosome aberrations in peripheral blood lymphocytes. Genetic polymorphisms for enzymes involved in metabolic detoxification (i.e. glutathione <it>S</it>-transferases) will also be analysed.</p> <p>Using standardized questionnaires, occupational exposure will be determined in exposed nurses only, whereas potential confounders (medicine consumption, lifestyle habits, diet and other non-occupational exposures) will be assessed in both groups of hospital workers.</p> <p>Statistical analysis will be performed to ascertain the association between occupational exposure to antineoplastic drugs and biomarkers of DNA and chromosome damage, after taking into account the effects of individual genetic susceptibility, and the presence of confounding exposures.</p> <p>Discussion</p> <p>The findings of the study will be useful in updating prevention procedures for handling antineoplastic drugs.</p