In situ colonization of marine biofilms on UNS S32760 duplex stainless steel coupons in areas with different water qualities: Implications for corrosion potential behavior

In the presence of biofilms, stainless steels （SS） exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential （Eco,） behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor （an anthropogenically disturbed area） was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms （especially Navicula sp.） on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island （an undisturbed area）. The ennoblement of Ecor values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Eco values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in imnortant gaps in this knowledge.     

A study of the environmental impacts of intelligent automated vehicle control at intersections via V2V and V2I communications

This article presents a novel intersection traffic management system for automated vehicles and quantifies its impact on fuel consumption and greenhouse gas emissions of CO₂ relative to traditional traffic signal and roundabout intersection control. The developed intelligent traffic management (ITM) techniques, which are based on a spatiotemporal reservation scheme, ensure that vehicles proceed through the intersection without colliding with other vehicles while at the same time reducing the intersection delay and environmental impacts. Specifically, the spatiotemporal reservation scheme provides each vehicle a collision-free path that is decomposed into a speed profile along with navigational instructions. The integration of the developed microscopic traffic simulator with instantaneous emission model, provides improved assessments of the environmental impact of traffic control strategies at intersections. The simulator architecture integrates several ITM algorithms, vehicle sensors, V2V/V2I communications, and emission and fuel consumption models. Each vehicle is modeled by an agent and each agent provides information depending on the specific vehicle sensors. The ITM system is supported by V2V and V2I communications, allowing the exchange of information among vehicles and infrastructure. The data include the estimated vehicle position and speed. Compared with traditional traffic management techniques, the simulation results prove that the proposed ITM system reduces CO₂ emissions significantly. The research also shows that these reductions are more significant when the traffic flow increases.     

The relevance of international transport costs on food prices: Endogenous and exogenous effects

The paper addresses the problem of transport costs and their influence on food prices for South American imports. While transport does not seem to be in the focus of existing analyses, its impact on food prices might be underestimated and even closely linked to the development of commonly mentioned drivers of food prices. Since transport price formation is a function of demand and supply, drivers of food prices are also expected to impact on transport prices. The authors argue that a number of relevant factors that drive transport costs - and in consequence food prices - can be influenced by policy makers. Based on empirical analysis, the authors explain the functioning of the determinants of transport costs in the segment of international shipping, trying to describe their exogenous and endogenous components. These results are discussed in reference to policy development in the region.     

Analysis of single pipeline pull-in procedure using small scale models

The structural elastic behaviour of steel pipelines during on-bottom pull-in procedure is investigated experimentally by using small scale models. Despite the lack of a sea-bed soil pipeline interaction effect in the model, it is possible to show that the unevenness of the sea-bed surface and the non-uniform distribution of friction forces can lead to large deflection bending stresses, higher than the numerical results yielded by standard software packages commonly used for design calculations. Due to foreseen difficulties in overcoming the drawbacks in practical and numerical procedures, the off-bottom pull-in operation arises as an attractive alternative even for shallow waters.     

An empirical comparison of disaggregate category and regression trip generation analysis techniques

Category and regression household trip generation analysis techniques were compared and contrasted. The comparative research was facilitated through a discussion that revealed the interchangeability of two methods of calibrating a category model. While the cell mean method is simple to implement, it does not readily yield statistical indexes for comparison with regression models. The general linear model analysis of variance (GLANOVA) readily provides statistical indexes for the comparison of category and regression trip generation models, and it produces identical empirical results to the simpler cell mean approach of calibrating a category model.The empirical comparison supports the widespread use of category models for trip generation analysis in transportation planning studies. It was found that regression and category models yielded equivalent results for typical planning applications at the district level of aggregation. In addition, both techniques estimated overall trip rate with equal accuracy in the calibration phase, and the two approaches were indistinguishable with respect to sample size sensitivity. However, households with extremely large trip rates were underestimated to a greater degree by category models than regression models. This tendency, in turn, resulted in larger calibration coefficients of determination for regression models. Since the cell mean method of calibrating a model is simpler and easier to understand than a regression model representation, category models can be recommended over regression models for planning studies.     

A method for solving the multi‐objective transit frequency optimization problem

Frequency setting takes place at the strategic and tactical planning stages of public transportation systems. The problem consists in determining the time interval between subsequent vehicles for a given set of lines, taking into account interests of users and operators. The result of this stage is considered as input at the operational level. In general, the problem faced by planners is how to distribute a given fleet of buses among a set of given lines. The corresponding decisions determine the frequency of each line, which impacts directly on the waiting time of the users and operator costs. In this work, we consider frequency setting as the problem of minimizing simultaneously users' total travel time and fleet size, which represents the interest of operators. There is a trade‐off between these two measures; therefore, we face a multi‐objective problem. We extend an existing single‐objective formulation to account explicitly for this trade‐off, and propose a Tabu Search solving method to handle efficiently this multi‐objective variant of the problem. The proposed methodology is then applied to a real medium‐sized problem instance, using data of Puerto Montt, Chile. We consider two data sets corresponding to morning‐peak and off‐peak periods. The results obtained show that the proposed methodology is able to improve the current solution in terms of total travel time and fleet size. In addition, the proposed method is able to efficiently suggest (in computational terms) different trade‐off solutions regarding the conflicting objectives of users and operators. Copyright © 2017 John Wiley & Sons, Ltd.     

“Cutting costs to the bone”: the Portuguese experience in renegotiating public private partnerships highways during the financial crisis

Transportation - How can governments renegotiate public private partnerships (PPPs) in order to reduce public expenditures? In 2011, in the aftermath of the financial and sovereign debt crisis,...     

The annual cycle of nanoflagellates in the Central Cantabrian Sea (Bay of Biscay)

The annual cycle of nanoflagellates (NF) including autotrophic (ANF), heterotrophic (HNF) and mixotropic (MNF) flagellates carried out in a temperate sea (Central Cantabrian Sea, southern Bay of Biscay) is presented. Three stations with characteristics ranging from coastal to oceanic conditions were analysed in order to compare NF response to this gradient. Samples were monthly collected at each station at three different depths between February 2002 and December 2002. CTD profiles were also taken at each station. NF were grouped according to their trophic status into ANF, HNF and MNF. Abundance and biomass were determined for each group. The annual cycle showed a general pattern consisting in a maximum in July with secondary maxima in March and October and minimum values in May. ANF were the most important fraction, making a major contribution (nearly 75%) to total NF biomass in all stations. HNF represented over 20% along the cycle, except for a peak in spring found in every station. MNF reached less than 5%, showing low seasonability. Small flagellates (2–5 µm) dominated throughout the cycle. Microplankton community was also analysed in terms of abundance and biomass. A significant positive correlation (r² = 0.49) was obtained between 2–5 µm NF and 10–20 µm HNF–MNF biomasses, suggesting a possible trophic relationship between these groups which should be cautiously taken. No significant relationships were found between microplankton and NF or between nutrients and ANF, indicating that the regulation of NF numbers is complex and probably implicates other groups. In addition to this, the unexpected 2002 Chl a concentration pattern and the misplacing of upwelling events render necessary to perform additional studies to fully understand the precise behaviour of NF in the Cantabrian Sea. To the best of our knowledge, this is the first study of a NF cycle in a temperate sea that considers all functional groups.     

Influence of the heavy fuel spill from the Prestige tanker wreckage in the overlying seawater column levels of copper, nickel and vanadium (NE Atlantic ocean)

The water column above the Prestige wreckage was sampled during two consecutive campaigns: Prestinaut (December 2002) two weeks after the tanker sunk and HidroPrestige0303 (March 2003) one month after the sealing of the main fuel leaks. Samples of the original cargo fuel and the emulsified fuel in the surface of the ocean were also collected. Analysis of the fuel indicated the release of 135 kg of Cu, 1700 kg of Ni and 5300 kg of V from the original fuel to the water column, remaining 35 kg of Cu, 3100 kg of Ni and 13,800 kg of V in the emulsified fuel. The metal partitioning between the water column and the emulsioned floating fuel, Cu > Ni ~ V, are in accordance with the stability index for the metal–nitrogen bond in metalloporphyrins. This release had an impact on dissolved trace metal concentrations in the water column. An increase on dissolved copper (2.8–4.7 nM) and nickel (2.2–8.0 nM) with respect to natural values (1–3 nM for Cu and 1.6–5 nM for Ni) was observed. Values for vanadium (28–35 nM) were in the range of pristine North Atlantic waters (30–36 nM). This contamination was especially observed in the upper water column (0–50 m), associated with the mixing of seawater with the fuel moving upwards, and in deep waters, where the residence time of fuel is higher. Future research in this field should focus on the environmental variables and the processes that control the release of contaminants from fuels for a better assessment of the contamination in oil-spill events.