Sail–sail and sail–hull interaction effects of hybrid-sail assisted bulk carrier

In a previously reported study, wind tunnel experiments were undertaken to investigate the aerodynamic characteristics of hybrid-sails in isolation. Such sails are seen as providing a worthwhile reduction in the delivered power to the propeller and hence the engine generated thrust, with a corresponding reduction in the CO₂ production of diesel engine exhaust. In this paper, wind tunnel testing is used to investigate sail–sail interaction effects for two sets of four identical hybrid-sails, and the sail–hull interaction effects for the same two sets of four identical sails in the presence of a bulk carrier hullform. The analysis presented suggests that to build a sail-assisted ship requires an appreciation of the sail–sail and sail–hull interaction effects.     

A reduced-gravity model of the Catalan Sea

A reduced-gravity model is used to study the effects of the wind on the upper layer circulation in the Catalan Sea. The model parameters were set by observed features of the circulation in the basin. It is shown that the results are particularly sensitive to the open sea boundary conditions. Simulations were done using the following boundary fluxes: (i) mean values estimated by Bethoux (1980) and (ii) more recent geostrophic transports computed from hydrographic data by Font et al. (1988). The latter seem to lead to more realistic circulation patterns. The influence of seasonal winds (climatological data) on the dynamics is clear, especially during the winter.     

Sediment geochemistry and mineralogy in Milos bay, SW Kyklades, Aegean Sea, Greece

This work aims at studying the geochemistry and mineralogy of Milos bay surface sediments. The bay forms an enclosed marine area, supplied totally by volcanic formations. Totally 16 samples were subjected to sedimentological (grain size), mineralogical (microscope examination and X-ray diffraction of the bulk sample and the pelitic fraction), and geochemical analyses (X-ray fluorescence in the pelitic fraction). Also the carbonate content was determined. Sediments were sandy with a high carbonate content (14–58%). The dominant minerals recognized in the pelitic fraction were smectite, kaolinite and illite, followed by chlorite, quartz, calcite, Mg-calcite and feldspars. In general, element concentrations appeared to be within the normal range, except Pb and Zn, which exhibited relatively high values. The Index of Geoaccumulation I_geo was computed, in order to investigate a possible enrichment of the surface sediments in metals. The analysis revealed again high values of I_geo class for both Pb and Zn. A careful study of the area, in relation to the quality of the catchment basins petrology, lead to a non-anthropogenic origin of these high concentrations. The enrichment of the surface sediments in Pb and Zn is attributed to the weathering of several mineral deposits, pyroclastic rocks and lavas, covering almost all Milos vicinity. A study of the geochemical data correlation coefficient matrix revealed three major groups of elements: (i) the elements of detrital origin represented by Si, Al, K and a part of the metals; (ii) the carbonates group; and (iii) a Fe–Mn oxyhydroxides–oxides group, which attracts a part of Pb, Cr and Ni.     

Urban form,travel time,and cost relationships with tour complexity and mode choice

The primary purpose of this study was to investigate how relative associations between travel time, costs, and land use patterns where people live and work impact modal choice and trip chaining patterns in the Central Puget Sound (Seattle) region. By using a tour-based modeling framework and highly detailed land use and travel data, this study attempts to add detail on the specific land use changes necessary to address different types of travel, and to develop a comparative framework by which the relative impact of travel time and urban form changes can be assessed. A discrete choice modeling framework adjusted for demographic factors and assessed the relative effect of travel time, costs, and urban form on mode choice and trip chaining characteristics for the three tour types. The tour based modeling approach increased the ability to understand the relative contribution of urban form, time, and costs in explaining mode choice and tour complexity for home and work related travel. Urban form at residential and employment locations, and travel time and cost were significant predictors of travel choice. Travel time was the strongest predictor of mode choice while urban form the strongest predictor of the number of stops within a tour. Results show that reductions in highway travel time are associated with less transit use and walking. Land use patterns where respondents work predicted mode choice for mid day and journey to work travel.

Fatigue design for plug/ring type gas welded joints of sts301l including welding residual stresses

This paper presents a fatigue design method for plug and ring type gas welded joints, which incorporates welding residual stress effects. A non-linear finite element analysis (FEA) was first performed to simulate the gas welding process. The numerically predicted residual stresses of the gas welds were then compared to experimental results measured using a hole drilling method. In order to evaluate the fatigue strength of the plug and ring type gas welded joints, a stress amplitude (σ _a ) _R taling the welding residual stress of the gas weld into account was introduced and is based on a modified Goodman equation incorporating the effect of the residual stress. Using the stress amplitude (σ _a ) _R , the ΔP-N _f relations obtained from fatigue tests for plug and ring type gas welded joints having various dimensions and shapes were systematically rearranged into (σ _a ) _R -N _f relations. It was found that the proposed stress amplitude (σ _a ) _R could provide a systematic and reasonable fatigue design criterion for the plug and ring type gas welded joints.     

Ergonomic and biomechnical analysis of automotive general assembly using XML and digital human models

Automotive general assembly requires many manual assembly operations to be carried out by human workers. Ergonomic analysis is an important part of the design and evaluation of products, jobs, tools, machines and environments for safe, comfortable and effective human functioning. Most recent researches have involved the evaluation of working conditions to prevent work-related musculoskeletal disorders. The majority of previous research on automotive companies has mainly considered the results of ergonomic analyses such as RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment) and OWAS (Ovako Working Posture Analysis System). Analysis of static posture including reachability, clearances for arm, hand and tool has also been used to evaluate working conditions. However, in addition to static posture analysis, a biomechanical analysis in dynamic conditions should also be conducted. There are no integrated frameworks or standard schema for ergonomic analysis using digital human models in digital environments. The purpose of this paper is to propose a new framework for the evaluation of working conditions by ergonomic and biomechanical analysis using digital models based on XML standard schema, including: products, processes, manufacturing resources and human workers. This paper presents the analysis results using the proposed framework for automotive general assembly operations. We propose a new framework for the evaluation of the assembly operations and their environments. Then we apply a digital human model to the dynamic simulation of general automotive assembly operations based on standard schemas in XML and PPRH (Product, Process, Resource and Human). Using PPRH information based on a standard XML schema to analyze the ergonomic and biomechanical results, the engineer can visualize, analyze and improve assembly operations and working environments in automotive general assembly shops using digital models.     

Parametric study of the main parameters influencing the catalytic efficiency of a diesel oxidation catalyst: Parameters influencing the efficiency of a diesel catalyst

This work studies the impact of five parameters: CO and HC engine-out emissions, space velocity, average value and profile of exhaust temperature, on Diesel CO and HC tail-pipe emissions. The first part of this work is conducted on a reactor and shows that both HC and CO light-off temperature increases with CO and HC input concentration. CO and HC initial concentration influence the adsorption/desorption capacities of HC only at high temperatures. Space velocity also influences CO and HC conversion efficiency. The second part of this work studies the impact of different combinations of HC and CO engine-out emissions on CO and HC conversion and tail-pipe emissions in the case of New European Driving Cycle. This part proposes that a Diesel oxidation catalyst must be mainly studied at the Urban Part of NEDC, as the CO and HC conversions are very high at the extra-urban part of NEDC. CO and HC conversion efficiencies are also dependent on exhaust temperature and catalytic volume. In the case of two different profiles of exhaust temperature with the same average temperature, CO and HC conversion efficiency is lower in the case of the smoother profile.     

Development of an LIF image processing technique for measuring drop sizes in a pre-swirl spray

Depth of field effects in laser sheet imaging were considered for droplet sizing of a pre-swirl spray. A pre-swirl spray is formed before the hollow-cone type main-swirl spray from a D.I. gasoline injector, and shows transient characteristics with high axial velocity. A microscopic imaging technique was applied to obtain high spatial resolution LIF tomograms of the pre-swirl spray. A 1 mm thick Nd:YAG laser sheet was used as a light source to make the LIF tomograms that were imaged using a high-resolution CCD camera. The droplet sizing of the pre-swirl spray was carried out using an image processing technique. In the image processing procedure, the laser sheet-straddling large-sized droplets were carefully taken into account to remove the errors caused by the depth of field effects from the limited thickness and the energy distribution of the laser sheet. The mean intensity of the individual droplets and the line profile of the LIF signal around the droplet edge were inspected to screen the laser sheet-straddling large-sized droplets. In order to consider the effects of the size-dependent LIF signal intensity, the size-classified or ensemble-averaged mean intensity of the individual droplets was introduced. The mean droplet sizes such as AMD and SMD were calculated using only screened droplets, and they slightly increase before considering the depth of field effects.     

Comparison of HC species from diesel combustion modes and characterization of a heat-up doc formulation

This study summarizes engine speed and load effects on HC species emissions from premixed charge compression ignition (PCI) and conventional diesel combustion, and it evaluates diesel oxidation catalyst (DOC) formulations on a gas flow reactor for the purpose of diesel particulate filter regeneration or lean NO_x trap desulfation. HC emissions are sampled simultaneously by a Tedlar bag for light HC species and by a Tenax TA™ adsorption trap for semi-volatile HC species, and they are analyzed by gas chromatography with a flame ionization detector. The bulk temperature and residence time during combustion are key parameters that are important for understanding the effects of speed and load on engine-out HC emissions. The degree of post-flame oxidation is higher in PCI than in conventional combustion, and it is increased for PCI with a higher speed and load, as indicated by a lower fuel alkanes/THC ratio, a higher alkenes/fuel alkanes ratio, and a higher methane/THC ratio. Ethene and n-undecane are two representative HC species, and they are used as a surrogate mixture in the gas flow reactor to simulate PCI and conventional combustion with in-cylinder post fuel injection. Among the three DOC formulations tested, the catalyst with constituent precious metals of platinum and palladium (PtPd) showed the best light-off performance, followed by PtPd with an addition of cerium dioxide (PtPd+CeO₂), and platinum (Pt), regardless of exhaust compositions. Conventional combustion exhaust composition shows a lower light-off temperature than that of PCI, regardless of catalyst formulation.