100 research outputs found
Advanced model for the calculation of meshing forces in spur gear planetary transmissions
This paper presents a planar spur gear planetary transmission model, describing in great detail aspects such as the geometric definition of geometric overlaps and the contact forces calculation, thus facilitating the reproducibility of results by fellow researchers. The planetary model is based on a mesh model already used by the authors in the study of external gear ordinary transmissions. The model has been improved and extended to allow for the internal meshing simulation, taking into consideration three possible contact scenarios: involute–involute contact, and two types of involute-tip rounding arc contact. The 6 degrees of freedom system solved for a single couple of gears has been expanded to 6 + 3n degrees of freedom for a planetary transmission with n planets. Furthermore, the coupling of deformations through the gear bodies’ flexibility has been also implemented and assessed. A step-by-step integration of the planetary is presented, using two typical configurations, demonstrating the model capability for transmission simulation of a planetary with distinct pressure angles on each mesh. The model is also put to the test with the simulation of the transmission error of a real transmission system, including the effect of different levels of external torque. The model is assessed by means of quasi-static analyses, and the meshing stiffness values are compared with those provided by the literature.The authors would like to acknowledge Project DPI2013-44860 funded by the Spanish Ministry of Science and Technology
Sustainable Value Added – Ein neues Maß des Nachhaltigkeitsbeitrags von Unternehmen am Beispiel der Henkel KGaA
Multiple carbon accounting to support just and effective climate policies
Negotiating reductions in greenhouse gas emission involves the allocation of emissions and of emission reductions to specific agents, and notably, within the current UN framework, to associated countries. As production takes place in supply chains,increasingly extending over several countries, there are various options available in which emissions originating from one and the same activity may be attributed to different agents along the supply chain and thus to different countries. In this way, several distinct types of national carbon accounts can be constructed. We argue that these accounts will typically differ in the information they provide to individual countries on the effects their actions have on global emissions; and they may also, to varying degrees, prove useful in supporting the pursuit of an effective and just climate policy. None of the accounting systems, however, prove 'best' in achieving these aims under real-world circumstances; we thus suggest compiling reliable data to aid in the consistent calculation of multiple carbon accounts on a global level
Social and Cultural Sustainability: Criteria, Indicators, Verifier Variables for Measurement and Maps for Visualization to Support Planning
Public Preferences for Forest Ecosystem Management in Japan with Emphasis on Species Diversity
We carried out online choice experiments (CE) to investigate what value Japanese individuals assign to rare versus familiar species in forest ecosystem, and to determine how preference heterogeneity arises. CE attributes comprised a forestry charge as the price attribute and rare versus familiar species of animals or plants as the good to be valued. Species numbers in a 5 km-mesh forest area were evaluated without the use of species names to focus purely on responses to numerical changes. Positional effects were also tested to validate results regarding alternatives and attributes other than the price attribute. A random parameter logit model was adopted to capture preferences for species diversity. After confirming that no positional effects existed, we found that (1) rare animals were valued more highly than rare plants, (2) familiar plants were assigned a positive value, but familiar animals were not assigned significant value at the mean parameter estimate, and (3) preference heterogeneities existed for all species. The sources of preference heterogeneity were analyzed with a latent class model having principal components of environmental attitudes. The influence of such attitudes was shown to be significant and suggested that attention should be paid to belief systems rather than solely demographics
From Economic General Equilibrium to Ecological System Services for Nature Conservation and Management: A Methodological Analysis and an Empirical Study Based on 30 Italian Industries
Gearbox dynamic modelling
The paper reports on current developments in gearbox dynamic modelling. It refers to Muller's one-mass two-parameter (stiffness and damping) gearbox model with rectilinear vibration. The paper shows that there is a need to develop a new model, which would incorporate torsional vibration. The paper refers to the previous papers on gearbox dynamic modelling published by the author in journals and conference proceedings. In the present paper, the influence of the clutch damping coefficient and one random parameter value from the three-parameter error mode, and that of the interaction between error parameters on the vibration generated by a gearbox system, is analyzed.Modelowanie dynamiki przekładni zębatych. Praca przedstawia aktualny rozwój zagadnień związanych z modelowaniem dynamiki przekładni zębatych. Nawiązuje ona do jednomasowego, dwuparametrowego (sztywność i tłumienie) modelu przekładni Mullera o ruchu prostoliniowym. Pokazuje potrzebę opracowania nowego modelu, który uwzględni drgania skrętne. Nawiązuje do wcześniejszych publikacji autora pracy na temat modelowania przekładni publikowanych w czasopismach i materiałach konferencyjnych. W presentowanej pracy przedstawiono analizę wpływu tłumienia w sprzęgle, wpływ losowego parametru w trójparametrowej funkcji błędu na drgania generowane przez przekładnię zębatą
Wspomaganie wnioskowania diagnostycznego modelowaniem matematycznym w zakresie od przekładni jednostopniowej do planetarnej
The paper shows possibilities of using mathematical modelling and computer simulations for supporting fault detection in gearbox systems. The paper refers to the model given by L. Muller in which the two wheels of a gear-set are reduced to one body. The paper gives the review of the systems with one and two-stage gear-sets. The models are used to investigate influence features/factors of systems with gear-sets to vibration. The torsional and lateral vibration is considered as the signal of a gearbox condition. The factors having influence to vibration signal are divided into four groups, that is: design factors, technology factors, operational factors and change of condition factors. The paper refers to modelling of planetary gearboxes. The paper also refers to the model-based fault diagnosis. Model-based is defined as determination of faults of the system from comparison of available gearbox system measurements with a priori information represented by the system's mathematical model, through generation of residual quantities.Praca pokazuje możliwości wykorzystania modelowania matematycznego i symulacji komputerowej do wspomagania wykrywania uszkodzeń w układach z przekładniami zębatymi. Praca nawiązuje do modelu L. Mullera w którym dwa koła zębate redukowane są do jednego ciała. Praca jest przeglądem układów z przekładnią jednostopniową i dwustopniową. Modele są używane do badania wpływu cech układu na z przekładniami zębatymi na generację drgań. Rozpatrywane są drgania skrętne i poprzeczne jako sygnał stanu przekładni. Czynniki wpływające na sygnał drganiowy podzielone są na cztery grupy a mianowicie: czynniki konstrukcyjne, technologiczne, eksploatacyjne i czynniki związane ze zmianą stanu. Praca nawiązuje również do modelowania przekładni planetarnych. Nawiązano również do diagnostyki opartej o modelowanie matematyczne (model- based diagnostic). Ten rodzaj diagnostyki zdefiniowano jako wykrywanie uszkodzeń w systemie na podstawie porównania bieżących wyników pomiarowych z informacjami przyjętymi a priori reprezentowanymi jako model matematyczny i powstającego w wyniku tego porównania sygnału rezydualnego
Problemy i rozwiązania w diagnostyce układów napędowych maszynowych gigantów podstawowych górnictwa odkrywkowego
In the paper is given discussion on demands connected with vibration signal analysis for condition monitoring of driving systems of monster machinery used in open cast mines. Because of external load variation which cause that the vibration signal generated by driving systems is no-stationary there is a need to use special techniques for signal analysis. The description of proper signal analysis techniques is given together with machinery description and external load characteristic. The description leads to design, production technology, operation, change of condition factors analysis [1].W pracy przedstawiona jest dyskusja o wymaganiach związanych z analizą drganiowego sygnału dla monitorowania układów napędowych maszynowych gigantów używanych w górnictwie odkrywkowym. Ponieważ drganiowe sygnały generowane przez układy napędowe na skutek zmienności obciążenia generują niestacjonarny sygnał istnieje potrzeba wykorzystania specjalnych technik do analizy sygnału. Przedstawiono opis niektórych maszynowych gigantów wraz z technikami analizy sygnałów i charakterystyki zmienności obciążenia. Opis prowadzi do analizy czynników konstrukcyjnych, technologicznych, eksploatacyjnych i zmiany stanu [1]
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