1,720,986 research outputs found
The effect of temperature fluctuations on the spread of a buoyant plume
No full textEmissions from many natural and anthropogenic sources are hot compared with the surrounding ambient air. Such buoyancy effects cause the emitted plume to rise, increasing the effective source height and significantly decreasing the maximum ground level concentrations (in the vicinity of the source). A major aspect that distinguishes buoyant and passive dispersion is that buoyant fluid particles create their own turbulence and hence exchange processes between the plume and its environment need to be accounted for. The inclusion of plume rise in Lagrangian stochastic models (LSMs) of turbulent dispersion has been considered by many authors but the interaction of the buoyant plume with the environment (by means of entrainment) is difficult to model in a Lagrangian framework. Webster and Thomson [8] formulated a hybrid model in which the mean flow is calculated from a simple plume model and the fluctuations of velocity are calculated using an LSM. They model the effect of turbulence generated by the plume by an additional random increment to the position of a particle. Here, instead of including this extra term, we add a stochastic differential equation (SDE) for the temperature fluctuations suitably coupled with the SDE for the velocity fluctuations. The interaction of temperature and velocity fluctuations, directly related to the turbulence within the plume, determines the plume’s spread. The results of the model are compared with large-eddy simulation (LES) of buoyant plumes in a uniform crosswind and also with the plume generated by the explosion and fire at the Buncefield oil depot in 2005 using realistic profiles of the wind speed and direction and thermal stratification
A Lagrangian dispersion model with a stochastic equation for the temperature fluctuations
No full textIndagini preliminari sulla conservazione del polline di Ranunculaceae ornamentali e sul suo potenziale utilizzo per la valutazione della tossicità dei fitofarmaci impiegati nelle coltivazioni in serra.
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MGM Marmi: challenging tradition with entrepreneurial leadership and business communication
No full textThis case explores the concept of entrepreneurial leadership. It aims to foster students’ reflection on leadership roles and traits and on the barriers, challenges, and opportunities new leaders and entrepreneurs face when they take over the management of an established, family-owned business. The case focuses on MGM Marmi, a family-owned company established in 1960 in Italy, before and after the company was formally taken over by the founder’s successor. Particular attention is paid to the figure of Laura Olivari, the wife of Umberto Guarda, the founder’s son, and the impact she exerted on the company.
The difficulty level of this case is appropriate for first year undergraduate students who are toward the end of an organizational behaviour module or for second-year undergraduates at the beginning of a leadership module. Aspects of business communication, diversity, and culture (à la Hofstede) are encompassed in the case context; therefore, students’ prior knowledge of such issues may facilitate discussion. The case is designed to be taught in a one-hour seminar and is expected to require one hour of individual preparation for students. Although it aims to foster a critical evaluation of the actor’s profile against the major leadership theories suggested, it also hopes to stimulate students to reflect upon the consequences that roles and traits may exert on a company’s choices. The company website indicated in the text and bibliography enrich the case-study experience by showing the products of the company as well as its presence in the national and international press.
This case was prepared for classroom discussion rather than to illustrate either effective or ineffective handling of an administrative, ethical, or legal decision by management. Information was gathered from public as well as corporate sources
Effetti del metodo irriguo sugli aspetti qualitativi del cavolo broccolo (Brassica oleracea L. var. italica Plenk)
No full textContenuto in antiossidanti e qualità del pomodoro “cherry” prodotto con differenti agrotecniche
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H15-159: Offline approach for higher order concentration moments and chemical reactions
No full textWe developed a fluctuating plume model able to evaluate all the higher concentration moments only requiring the knowledge of the first one. The simple algorithm used to calculate the meander centroid component is independent of the method used to obtain the mean concentration field and makes the computational time lower than most meandering plume model versions. Thus it is especially suitable for practical applications
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