•The potential of butanol has been investigated at partial load operation.•Torque and thermal efficiency slightly decrease when the alcohol content increases.•At part load, spark advance does not ...require changes when alcohol content increases.
Biofuels seem to represent one of the most promising means for the limitation of the greenhouse gas emissions coming from traditional energy systems.
In this paper, the performance of a “downsized” spark-ignition engine, fueled by gasoline and bio-butanol blends (20% and 40% butanol mass percentage), has been analyzed.
In the first phase of this activity, the experimental tests have been carried out at operating points ranging from low to medium engine speed and load.
The first investigations were aimed to assess the main differences among the different fuels in terms of output torque, thermal efficiency, combustion duration and optimal spark timing. In order to study the engine behavior in a wide range of fuel mixtures, these parameters have been evaluated for equivalence ratio values ranging from 1.25 to 0.83.
The results obtained in this step show that both the engine torque and thermal efficiency slightly decrease (meanly about 4%) when the blend alcohol content increases. However, butanol increases the burning rate of lean mixtures and an interesting result is that the spark advance does not require adjustments when fueling changes from neat gasoline to bio-butanol/gasoline blends.
Later, the pollutant emissions and the CO2 emissions, for both rich and lean mixtures of pure gasoline and gasoline bio-butanol blends, have been measured. In general, firing with alcohol blends, NOx and CO emissions remain quite the same, HC emissions slightly decrease while the CO2 emissions slightly increase.
At the end, in order to reproduce the real world urban driving cycle, stoichiometric mixtures have been analyzed. In these conditions, the engine thermal efficiency, at given speed and torque, has been evaluated for each kind of fueling. The results obtained in these operating points have shown that the alcohol blend fueling performs an efficiency penalty less than 2 percent.
The potential of a simple variable valve timing (VVT) system has been investigated. This system has been designed to update a small displacement engine pursuing the objective of optimizing both ...engine performance and, particularly, fuel consumption at part load operation. A continuously variable cam phaser (CVCP), able to produce a reverse Miller cycle effect during the intake phase and a significant internal EGR generation at the end of the exhaust stroke, has been introduced. A numerical approach, based on both 1-D and 3-D computational models, has been adopted in order to evaluate the engine performance when load is controlled by the VVT system and to deeply investigate the influence, on in-cylinder phenomena, of the valve timing variation. In this way, the VVT system here analyzed revealed as an effective tool in reducing the pumping losses, hence the specific fuel consumption, at partial load.
A statistical approach to LiDAR derived topographic attributes for the automatic extraction of channel network and for the choice of the scale to apply for parameter evaluation is presented in this ...paper. The basis of this approach is to use distribution analysis and statistical descriptors to identify channels where terrain geometry denotes significant convergences. Two case study areas with different morphology and degree of organization are used with their 1 m LiDAR Digital Terrain Models (DTMs). Topographic attribute maps (curvature and openness) for various window sizes are derived from the DTMs in order to detect surface convergences. A statistical analysis on value distributions considering each window size is carried out for the choice of the optimum kernel. We propose a three-step method to extract the network based (a) on the normalization and overlapping of openness and minimum curvature to highlight the more likely surface convergences, (b) a weighting of the upslope area according to these normalized maps to identify drainage flow paths and flow accumulation consistent with terrain geometry, (c) the standard score normalization of the weighted upslope area and the use of standard score values as non subjective threshold for channel network identification. As a final step for optimal definition and representation of the whole network, a noise-filtering and connection procedure is applied. The advantage of the proposed methodology, and the efficiency and accurate localization of extracted features are demonstrated using LiDAR data of two different areas and comparing both extractions with field surveyed networks.
Abstract Despite significant advances in the fabrication of bioengineered scaffolds for tissue engineering, delivery of nutrients in complex engineered human tissues remains a challenge. By taking ...advantage of the similarities in the vascular structure of plant and animal tissues, we developed decellularized plant tissue as a prevascularized scaffold for tissue engineering applications. Perfusion-based decellularization was modified for different plant species, providing different geometries of scaffolding. After decellularization, plant scaffolds remained patent and able to transport microparticles. Plant scaffolds were recellularized with human endothelial cells that colonized the inner surfaces of plant vasculature. Human mesenchymal stem cells and human pluripotent stem cell derived cardiomyocytes adhered to the outer surfaces of plant scaffolds. Cardiomyocytes demonstrated contractile function and calcium handling capabilities over the course of 21 days. These data demonstrate the potential of decellularized plants as scaffolds for tissue engineering, which could ultimately provide a cost-efficient, “green” technology for regenerating large volume vascularized tissue mass.
In the last decades the Euro-Mediterranean region has experienced an increase in extreme temperature events such as heat waves. These extreme weather conditions can strongly affect arable crop growth ...and final yields. Here, early heat waves over Italy from 1995 to 2013 are identified and characterised and their impact on durum wheat yields is investigated. As expected, results confirm the impact of the 2003 heat wave and highlight a high percentage of concurrence of early heat waves and significant negative yield anomalies in 13 out of 39 durum wheat production areas. In south-eastern Italy (the most important area for durum wheat production), the percentage of concurrent events exceeds 80 %.
In this work, the behavior of an engine running with binary and ternary mixtures of n-butanol, ethanol and gasoline has been investigated.
Analyses have been performed at different engine speed both ...at low load and at high load. For each blend, the air to fuel ratio has been kept stoichiometric, while the spark time has been tuned in order to maximize the engine brake torque and hence the engine fuel conversion efficiency. The performance, the combustion characteristics and the pollutant emissions of the engine fueled by biofuel mixtures have been compared to those characterizing the engine running with neat gasoline.
In an attempt to provide a guideline for the development of engines running with every mix of gasoline and alcohol, measurements are presented as a function of the oxygen content of the fuel. When the fuel oxygen content increases, results show that the optimal spark time must be retarded at part load while must be advanced at high load. At this operation, the maximum obtainable efficiency increases, the CO2 specific emissions decrease almost linearly together with NOx and HC specific emissions, the engine torque remains practically the same, while the brake specific fuel consumption increases.
An engine running with alcohol-gasoline blends has been investigated. Analyses have been performed at different engine speed both at low load and at high load. The air to fuel ratio has been kept stoichiometric. When the alcohol content increases, results show that the optimal spark time must be retarded at part load while must be advanced at high load. At this operation, the maximum obtainable efficiency increases and the CO2 specific emissions decrease. The engine torque remains practically the same, while the brake specific fuel consumption increases. Trends are almost linearly with respect to the fuel oxygen content. Display omitted
•A spark ignition engine running with alcohol/gasoline blends has been investigated.•When the alcohol content increases:•the maximum obtainable engine efficiency increases.•the spark timing must be retarded at part load and advanced at high load.•specific CO2 emissions decrease.•A guideline for tuning of engines burning alcohol-gasoline blend has been obtained.
Antiphospholipid Syndrome (APS) is an autoimmune disease which was defined in the early 1980s. The principal features include thromboembolic events and/or pregnancy losses in association with ...antiphospholipid antibodies (aPL). As an historical note, the full-blown picture of the syndrome resembles the illness suffered by Anne Stuart, Queen of England in the XVIII century, whose repeated miscarriages caused the end of the royal Stuart line and the Hanoverian succession. The identification of aPL started in the early XX century and was linked to the introduction of the serological test for the diagnosis of syphilis. This involves a reaction between an antibody (reagin) and a phospholipid antigen derived from bovine heart (cardiolipin). Later on, it was observed that not all subjects with a positive test had syphilis, and that the so called "false positive reaction" was often reported in patients with systemic lupus erythematosus. Different tests for the identification of aPL were subsequently developed: first lupus anticoagulant (1971) and then immunoassays for anticardiolipin (1983) and anti-beta2 glycoprotein I (1990) antibodies. In the same period the association between the presence of circulating aPL and thrombotic and obstetric events was established, both in patients with autoimmune diseases and in otherwise healthy subjects, leading to the identification of APS as a distinct autoimmune disease. This has allowed better diagnosis and more targeted treatment for many patients.
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•Bio-fuels will reduce the overall CO2 emission.•The properties of butanol/gasoline–air mixtures have been determined.•A 1-D model of a SI engine has been calibrated and ...validated.•The butanol content reduces the combustion duration.•The optimal ignition timing slightly changes.
In this paper, the performance of a turbocharged SI engine, firing with butanol/gasoline blends, has been investigated by means of numerical simulations of the engine behavior. When engine fueling is switched from gasoline to alcohol/gasoline mixture, engine control parameters must be adapted. The main necessary modifications in the Electronic Control Unit have been highlighted in the paper.
Numerical analyses have been carried out at partial load operation and at two different engine speeds (3000 and 4000rpm). Several n-butanol/gasoline mixtures, differing for the alcohol contents, have been analyzed.
Such engine performances as torque and indicated efficiency have been evaluated. Both these characteristics decrease with the alcohol contents within the mixtures. On the contrary, when the engine is fueled by neat n-butanol, torque and efficiency reach values about 2% higher than those obtained with neat gasoline.
Furthermore, the optimal spark timing, for alcohol/gasoline mixture operation, must be retarded (up to 13%) in comparison with the correspondent values of the gasoline operation.
In general, engine performance and operation undergo little variations when fuel supplying is switched from gasoline to alcohol/gasoline blends.
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