24 research outputs found
Development of an Exhaust System for Agricultural Tractors
No full textThe main sources of sound emitted by vehicles are the engine and the rolling noise produced by the tires. In case agricultural tractors are considered, the engine and the transmission are responsible of the main emissions since they often work in the fields on soft ground at low speeds. This work focuses on the combined acoustic and mechanical development of a new exhaust system for an existing agricultural tractor, with the aim of providing a product with improved acoustic performances and a neater design. The host vehicle is equipped with a 300 hp diesel engine which can be particularly noisy at low rpm, with a further constraint being the “under the bonnet” available volume to fit the system into. The existing exhaust system is the baseline for the engineering process. The acoustic design is carried out by a 1D simulation software based on an electro-acoustic analogy, while the design modelling is performed by using Solidworks® 3D CAD. After the design stage a prototype has been manufactured and tested at the MWL/KTH laboratory. The engineering process gave the product a cleaner design and allowed to identify feasible solutions ensuring increased sound attenuation performances
Promotion of Destinations of Excellence: Reevaluation of a Medieval Tourist Route – Guidone’s Itinerary (1119 a.d.)
No full text
Molecular markers of hepatocellular carcinoma: RT-PCR study of uPA, uPAR and t-PA mRNAs.
No full textQuantitative in situ hybridization for the evaluation of gene expression in asynchronous and synchronized cell cultures and in tissue sections
No full textWe describe an image analysis (IA) system that has been applied for the quantitative evaluation of mRNAs evidenced by in situ hybridization (ISH) with radiolabelled probes in cultured cells and in tissue sections. The ISH-IA method was used for the evaluation of cultured cell morphological parameters such as cell and nucleous area (CA and NA, respectively) in parallel with the levels of mRNAs detected as hybridization grains areas (GA). The evaluation of these parameters, together with the analysis of the levels of mRNAs (c-jun, cyclin A) specific for given cell cycle phases (i.e. G1 and S/G2), allowed the identification, in asynchronous cultures of human skin fibroblasts, of cells in G1 and S/G2 phases. The mRNA levels measured by ISH-AI were comparable with those detected by RT-PCR. This method was also applied for the analysis of fibronectin (FN) gene expression in control skin fibroblasts in relationship with the different phases of the cell cycle and in comparison with a tumor cell line (Sk-Hep1), heterogeneous either for morphometric parameters or for the levels of this transcript. Finally, the ISH-AI was applied for the semiquantitative evaluation of the expression, localization and alternative splicing pattern of FN mRNA in normal liver and in hepatocellular carcinoma (HCC) tissue sections
Assessment of Energy Consumption and Range in Electric Vehicles with High Efficiency HVAC Systems Based on the Tesla Expander
No full textBattery electric vehicles (BEVs) are considered one of the most promising solution to improve the sustainability of the transportation sector aiming at a progressive reduction of the dependence on fossil fuels and the associated local pollutants and CO2 emissions. Presently, the major technological obstacle to a large scale diffusion of BEVs, is the fairly low range, typically less than 300 km, as compared to classical gasoline and diesel engines. This limit becomes even more critical if the electric vehicle is operated in severe weather conditions, due to the additional energy consumption required by the cabin heating, ventilating, and air-conditioning (HVAC). The adoption of vapor-compression cycle, either in heat pump or refrigerator configuration, represents the state-of-the-art technology for HVAC systems in vehicles. Such devices typically employ an expansion valve to abruptly reduce the pressure causing the flash evaporation of the working fluid. This component, although necessary to provide the cooling effect, is also responsible of a significant exergy loss, which reduces the efficiency of the thermodynamic cycle. In this paper we study the possible benefits in terms of energy saving and consequent increase of the driving range, that can be obtained in electric vehicles that adopt a high efficiency HVAC system, where the Tesla turbine replaces the classical expansion valve in order to recover part of the exergy typically lost by the working fluid in the expansion phase. First, an off-design thermodynamic model was developed to assess the performance of the proposed HVAC system as function of the ambient temperature. Then, the calculated COP curves were implemented in an in-house Matlab code based on Nissan Leaf design data. Simulations are carried out considering various reference driving cycles showing that this solution may result in a potential increase of the electric vehicle range up to 5%
