Dynamic behaviour of materials

A simple unstructured mathematical model for the oxidation of glucose to 2,5-diketo-D-gluconic acid with Erwinia citreus was developed. The kinetic parameters of the model were estimated by the oxygen partial pressure method and directly from the temporal response obtained from the experimental data collected in the batch fermentation. The simple developed model based on the kinetic measurements was able to simulate quite well the dynamic behaviour of the batch fermentation.

In this work the dynamic behaviour of the one-dimensional family of maps F p,q (x) = 1/(1 À px À qx 2 ) is examined, for specific values of the control parameters p and q. Lyapunov exponents and bifurcation diagrams are numerically calculated. Consequently, a transition from periodic to chaotic regions is observed at values of p and q, where the related maps correspond to Fibonacci generating functions associated with the golden-, the silver-and the bronze mean.

To accurately predict the dynamic behaviour of spanwise uniform, non-homogeneous, anisotropic beams with arbitrary cross-sectional geometry is an important part of engineering analysis. Classical one-dimensional beam theory fails in this endeavour, and development of more sophisticated one-dimensional theories is an important task. A basis for development of improved one-dimensional theory is the dispersion curve analysis. A means to find the dispersion curves is discussed in this paper. The code is developed to calculate the dispersion curves, as well as corresponding mode shapes. The code is based on finite element discretization over the cross-sectional domain. Use of this code provides benchmark results for the testing of any existing one-dimensional theory, as well facilitating the construction of new one-dimensional theories. Dispersion information can be also useful in non-destructive evaluation. As an example of a case where non-classical effects are particularly important, results obtained from this code for an I-beam are presented. Qualitative comparison with the well-known case of isotropic rectangular beam is provided. Features that are common for all beams are emphasized along with pointing out qualitative differences that exist for beams other than rectangular or circular.

An important contributory factor to the bullwhip effect (i.e. the variance amplification of order quantities observed in supply chains) is the replenishment rule implemented by supply chain members. We analyse the bullwhip effect induced by the use of different forecasting methods in order-up-to replenishment policies. We not only quantifY the variance amplification, but we prove that the bullwhip effect is guaranteed irrespective of the forecasting method used. Avoiding the bullwhip effect consequently means avoiding the order-up-to policies. In a second part of the paper we introduce a general decision rule that avoids variance amplification and succeeds in generating smooth ordering patterns, even when demand has to be forecasted. The methodology is based on control systems engineering and allows us to gain important insights in the dynamic behaviour of replenishment rules.

The paper is aimed at presenting the dynamic behaviour of a wind turbine equipped with a doubly fed induction generator (DFIG) in case of disturbances in the interconnected grid. A model of a DFIG is presented and adapted for analyzing the response of the wind generator to voltage control, frequency control, voltage sags and wind variations. Simulations, performed by a widely used power system analysis code, are reported and commented.

Occupants' behaviour when improving the indoor environment plays a significant role in saving energy in buildings. Therefore the key step to reducing energy consumption and carbon emissions from buildings is to understand how occupants interact with the environment they are exposed to in terms of achieving thermal comfort and well-being; though such interaction is complex. This paper presents a dynamic process of occupant behaviours involving technological, personal and psychological adaptations in response to varied thermal conditions based on the data covering four seasons gathered from the field study in Chongqing, China. It demonstrates that occupants are active players in environmental control and their adaptive responses are driven strongly by ambient thermal stimuli and vary from season to season and from time to time, even on the same day. Positive, dynamic, behavioural adaptation will help save energy used in heating and cooling buildings. However, when environmental parameters cannot fully satisfy occupants' requirements, negative behaviours could conflict with energy saving. The survey revealed that about 23% of windows are partly open for fresh air when air-conditioners are in operation in summer. This paper addresses the issues how the building and environmental systems should be designed, operated and managed in a way that meets the requirements of energy efficiency without compromising wellbeing and productivity.

Sommario Il presente lavoro è dedicato alla modellazione analitica ed alla validazione sperimentale di smorzatori a correnti parassite di tipo a riluttanza. Tali smorzatori elettromagnetici sfruttano la variazione di flusso concatenato agli avvolgimenti di una bobina per generare correnti parassite all'interno degli avvolgimenti stessi e quindi dissipare energia meccanica. L'effetto smorzante è di interesse applicativo per lo smorzamento di vibrazioni. L'analisi dinamica del sistema elettromeccanico è stata condotta mediante il formalismo bond graph. I modelli sviluppati sono poi stati validati sperimentalmente su due banchi prova con differenti geometrie di circuito magnetico e diversa configurazione della struttura vibrante. La campagna di prove sperimentali condotta sui due banchi per varie condizioni di funzionamento, ha permesso di validare i modelli matematici e di comparare le prestazioni ottenibili con le due configurazioni magnetiche. Il confronto analitico/sper...

In 2003 the IAEA has initiated a Coordinated Research Project (CRP) on "Studies of Advanced Reactor Technology Options for Effective Incineration of Radioactive Waste". Major intermediate results have been obtained and will be reported here. The overall objective of the CRP, performed within the framework of IAEA's Nuclear Energy's Department Technical Working Group on Fast Reactors, is to increase the capability of Member States in developing and applying advanced technologies in the area of long-lived radioactive waste utilization and transmutation. Sixteen institutions from 12 member states and one international organization participated in this CRP. The CRP concentrated on the assessment of the dynamic behaviour of various transmutation systems. The reactor systems investigated comprise critical reactors, subcritical accelerator driven systems with heavy liquid metal and gas cooling, critical molten salt systems and hybride fusion/fission systems. Both fertile and fertile-free fuel options have been investigated. For a deep assessment of the transient and safety behaviour, the analytical capabilities have to be qualified. A major effort of the CRP consisted in the benchmarking of steady state core configurations and performing transient/accident simulations. For a general assessment and comparison, the safety coefficients were determined for the individual systems. In a second step transient analyses were performed which reflected the generic behaviour of the various reactors types. In addition the transmutation potential, burn-up behaviour and decay heat of minor actinide bearing fuels were investigated.

SOMMARIO Il comportamento dinamico di edifici in c.a. progettati per i soli carichi verticali è stato analizzato, al fine di valutarne la vulnerabilità sismica nonché l'efficacia di alcune tecniche di miglioramento, mediante analisi non lineari sia statiche che dinamiche su modelli di telai piani a plasticità concentrata, considerando diversi possibili comportamenti delle cerniere plastiche e utilizzando differenti gruppi di terremoti naturali. Le analisi svolte hanno evidenziato prestazioni sismiche della struttura superiori a quelle attese, tanto che gli edifici della tipologia considerata sembrano avere capacità non trascurabili per resistere ad azioni orizzontali, purché i difetti tipici della configurazione strutturale originaria, connessi all'impostazione non sismica del progetto, vengano opportunamente eliminati. SUMMARY Dynamic behaviour of GLD buildings has been studied by means of non linear static and dynamic analyses, in order to evaluate the corresponding seis...