Application of CGP-cross route process for microstructure refinement and mechanical properties improvement in steel sheets

A modified method of severe plastic deformation (SPD) entitled constrained groove pressing-cross route (CGP-CR) was introduced for imposing a high magnitude of equivalent strain of about 2.32 per pass on the sheet form samples. The major benefit of this improved route compared to previous common route was the more homogeneity of strain in the rolling (RD) and transverse (TD) directions of sheets. In this study, low carbon steel samples were used for examination of evolutions in microstructure and mechanical properties during SPD via CGP-CR process. Mechanical properties improvement were measured by tensile and macro hardness tests. The results indicate that CGP-CR process can effectively improve tensile strength; and also, yield stress and hardness of as-received low carbon steel samples were improved up to about 100% after two deformation passes. Also, high magnitude of inhomogeneity can be observed in hardness distribution through first pass of the process which diminishes in the subsequent passes. Microstructural evolutions during process were monitored by optical microscopy observations and X-ray diffraction analysis. The results demonstrate that initial ferritic microstructure with grain size of about 30 μm was refined to a 225 nm cell structure after two passes of CGP-CR process.     

Coastal flooding,climate change and environmental justice: identifying obstacles and incentives for adaptation in two metropolitan Boston Massachusetts communities

We explored the possible future impacts of increased coastal flooding due to sea level rise and the potential adaptation responses of two urban, environmental justice communities in the metropolitan Boston area of Massachusetts. East Boston is predominantly a residential area with some industrial and commercial activities, particularly along the coastal fringe. Everett, a city to the north of Boston, has a diversified industrial and commercial base. While these two communities have similar socioeconomic characteristics, they differ substantially in the extent to which residents would be impacted by increased coastal flooding. In East Boston, a large portion of residents would be flooded, while in Everett, it is the commercial/industrial districts that are primarily vulnerable. Through a series of workshops with residents in each community, we found that the target populations do not have an adaptation perspective or knowledge of any resources that could assist them in this challenge. Furthermore, they do not feel included in the planning processes within their communities. However, a common incentive for both communities was an intense commitment to their communities and an eagerness to learn more and become actively engaged in decisions regarding climate change adaptation. The lessons that can be applied to other studies include 1) images are powerful tools in communicating concepts, 2) understanding existing cultural knowledge and values in adaptation planning is essential to the planning process and 3) engaging local residents at the beginning of the process can create important educational opportunities and develop trust and consensus that is necessary for moving from concept to implementation.     

External force-assisted laser forming process for gaining high bending angles

Laser forming process is used in forming and bending of metallic and non-metallic sheets. Laser beam irradiation causes a localized temperature increase and a localized mechanical strength decrease. In this article, an external mechanical force is added to a laser beam irradiation, which is called external force-assisted laser forming process, to gain a 90-degree bending angle. Furthermore, Numerical simulation of the process is performed to achieve a good understanding of the process. Simulation results show that more than two-third of the final forming is due to the laser beam irradiation. Equivalent plastic strain values during laser forming and external force-assisted laser forming processes are compared. Results show that equivalent plastic strain in laser forming process increases in a step pattern, with increasing in scan pass numbers. This occurs because when the laser beam irradiates on the sheet surface, it reduces the yield strength of the sheet. Equivalent plastic strain in external force-assisted laser forming process has an oscillatory step nature. This attributes to simultaneous effects of strain hardening and thermal induced reduction of yield strength of the sheet. Simulations were in good accordance with experiments.     

Influence of overlap between the laser beam tracks on surface quality in laser polishing of AISI H13 tool steel

Polishing by laser beam radiation is a novel manufacturing process to modify the initial surface topography in order to achieve a desired level of surface finish. The performance of laser polishing (LP) is determined by an optimum combination of several key process parameters. In this regard, the overlap between two successive laser beam tracks is one of the important LP process parameters, which has a significant effect over the final surface quality. In the current study, influence of overlap between the laser beam tracks on surface quality was experimentally investigated during the laser polishing of AISI H13 tool steel. Surface areas were polished by using four different overlap percentages (e.g. 80%, 90%, 95%, and 97.5%) while applying the same energy density. The improvement of surface quality was estimated through the analysis of line profiling surface roughness R_a, areal topography surface roughness S_a, and material ratio function. Also, individual components of the surface quality, e.g. waviness and roughness, and their evolution during LP were statistically analyzed using the power spectral density and the transfer functions. Finally, as an example of the best achieved LP result, flat surface area was polished using optimum set of the process parameters improving surface quality by 86.7% through the reduction of an areal topography surface roughness S_a from 1.35 μm to 0.18 μm.     

Incorporating stakeholder decision support needs into an integrated regional Earth system model

A new modeling effort exploring the opportunities, constraints, and interactions between mitigation and adaptation at regional scale is utilizing stakeholder engagement in an innovative approach to guide model development and demonstration, including uncertainty characterization, to effectively inform regional decision making. This project, the integrated Regional Earth System Model (iRESM), employs structured stakeholder interactions and literature reviews to identify the most relevant adaptation and mitigation alternatives and decision criteria for each regional application of the framework. The information is used to identify important model capabilities and to provide a focus for numerical experiments. This paper presents the stakeholder research results from the first iRESM pilot region. The pilot region includes the Great Lakes Basin in the Midwest portion of the United States as well as other contiguous states. This geographic area (14 states in total) permits cohesive modeling of hydrologic systems while also providing strong gradients in climate, demography, land cover/land use, and energy supply and demand. The results from the stakeholder research indicate that, for this region, iRESM should prioritize addressing adaptation alternatives in the water resources, urban infrastructure, and agriculture sectors, including water conservation, expanded water quality monitoring, altered reservoir releases, lowered water intakes, urban infrastructure upgrades, increased electric power reserves in urban areas, and land use management/crop selection changes. For mitigation in this region, the stakeholder research implies that iRESM should focus on policies affecting the penetration of renewable energy technologies, and the costs and effectiveness of energy efficiency, bioenergy production, wind energy, and carbon capture and sequestration.     

Opportunities to reduce greenhouse gas emissions from households in Nigeria

Efforts to mitigate climate threats should not exclude the household as the household is a major driver of greenhouse gas (GHG) emissions through its consumption patterns. This paper derives an emission index that could be used to estimate inventories of carbon dioxide (CO₂) emissions from kerosene combustion for lighting in Nigeria and also looks at the implications of solar pv lighting replacing kerosene lamp in Nigeria. Findings indicate that (1) average CO₂ emissions from kerosene combustion for lighting in Nigeria is about 0.06 kg per hour per lamp, which can be taken as the kerosene lamp CO₂ emission index for Nigeria. (2) about 3 × 10W_p solar pv will be required to replace a kerosene lamp, while about 0.124 tonnes of CO₂ will be avoided per lamp per year, operating at 6 h daily. At the national level, under the kerosene lamp replacement projection assumptions made, between 0.4 and 1.0 million tonnes of CO₂ will be avoided per year. The household investment required to owe a solar pv, including the capital cost of switching from kerosene lamp, is about US356, while the national capital investment outlay is between 1,138.265 and US356, while the national capital investment outlay is between 1,138.265 and US2,848 million. (3) Certified Emission Reduction (CER) units, assuming CO₂ is traded, will generate significant annual revenues on the order of 6.96 to almost US17.4 million per year, while earnings from unspent household kerosene fuel could amount to between 2,520 and US17.4 million per year, while earnings from unspent household kerosene fuel could amount to between 2,520 and US6,300 million over the life span of the solar pv. The micro-economic assessment carried out indicates the non-attractiveness of solar pv use at the household level, and (4) to promote solar pv use, both long and short term policy measures that aim at cost reduction were suggested. The paper concludes that, factoring the suggested measures into the climate, energy, and financial policy decision discourse in Nigeria could empower the households to play a significant role in achieving global CO₂ emission reduction, but at the local level.     

Observed LATCH use and misuse characteristics of child restraint systems in seven states

INTRODUCTION: Although the LATCH System (Lower Anchors and Tethers for Children) holds the promise of simplifying the installation of a child restraint system (CRS) to the vehicle's seat, many drivers transporting young children have difficulties using this technology. This paper reports on an observation study of LATCH use and misuse. METHOD: Observations of approximately 1,000 children less than 5 years of age in CRSs, in the back seats of vehicles that were equipped with tether and lower anchors, in seven states. RESULTS: Tethers were used for 51% of the children when the forward-facing CRS had tether straps and the vehicle had tether anchors. Lower anchors were used for 58% of the children when the CRS had lower attachments and the vehicle had lower anchors. The most common tether and lower attachment misuses were loose tether straps (18% of cases) and loose lower attachment installation (30% of the cases), respectively. Vehicle safety belts were used in combination with lower attachments in 20% of all lower anchor installations. CONCLUSION: As more caregivers of young children drive vehicles equipped with LATCH, it will be important to promote the proper installation of CRSs using this technology. LATCH education messages must also emphasize that the lower anchors may not always be the safest choice for CRS attachment -- the safest attachment is the one that results in a tight fit and will be used correctly consistently.     

Parasitoid-induced mortality of Araneus omnicolor (Araneae, Araneidae) by Hymenoepimecis sp. (Hymenoptera, Ichneumonidae) in southeastern Brazil

All species included in the Polysphincta genus-group develop as ectophagous parasitoids of active spiders, killing their hosts prior to pupation. However, little information regarding natural history and ovipositing behavior of most species are available. In this study we inspected 85 webs of Araneus omnicolor to evaluate the frequency of parasitism and host size preferences of the wasp Hymenoepimecis sp. We also described the web characteristics of normal and parasitized spiders and the wasp ovipositing behavior. About 41% of the adult females of A. omnicolor inspected were parasitized. The highest incidence of parasitism was observed among relatively small females while no egg or larva was found in large individuals. Araneus omnicolor builds a strong web composed of an orb and barrier threads, where the spider rests within a curled leaf. The parasitoid larva builds its cocoon within this refuge, and modified cocoon webs were not observed. The ovipositing behavior of Hymenoepimecis sp. was very similar to that of Hymenoepimecis argyraphaga parasitizing Leucauge argyra, including the position of the sting, the killing of a previously attached larva, and the expelling of the egg from the base of the ovipositor.     

A new THOR shoulder design: a comparison with volunteers, the Hybrid III, and THOR NT

OBJECTIVE: Since the shoulders are rarely seriously injured in frontal or oblique collisions, they have been given low priority in the development of frontal impact crash test dummies. The shoulder complex geometry and its kinematics are of vital importance for the overall dummy kinematics. The shoulder complex also influences the risk of the safety belt slipping off the shoulder in oblique forward collisions. The first aim of this study was to develop a new 50th percentile male THOR shoulder design, while the second was to compare the new shoulder, mounted on a THOR NT dummy, with volunteer, THOR NT, and Hybrid III range of motion and stiffness data. The third aim was to test the repeatability of the new shoulder during dynamic testing and to see how the design behaves with respect to belt slippage in a 45 degrees far-side collision. METHODS: The new 50th percentile THOR shoulder design was developed with the aid of a shell model of the seated University of Michigan Transportation Research Institute (UMTRI) 50th percentile male with coordinates for joints and bony landmarks (Schneider et al., 1983). The new shoulder design has human-like bony landmarks for the acromion and coracoid processes. The clavicle curvature and length are also made similar to that of a male human, as is the range of motion in the anterior-posterior, superior-inferior, and medial-lateral directions. The new shoulder design was manufactured and tested under the same conditions that T?rnvall et al. (2005b) used to compare the shoulder range of motion for the volunteers, Hybrid III, and THOR Alpha. The new design was also tested in two dynamic test configurations: the first was a 0 degrees full-frontal test and the second was a 45 degrees far-side test. The dummy tests were conducted with an R-16 seat with a three-point belt, the Delta V was 27.0+/-0.5 km/h and the maximum peak acceleration was approximately 14.6+/-0.5 g for each test. RESULTS: A new shoulder design with geometry close to that of humans was developed to be retrofitted to the THOR NT dummy. The results showed that the range of motion for the new shoulder complex during static loading was larger by at least a factor of three, for the maximum load (200 N/arm), than that of either the Hybrid III or the THOR NT; this means it was more similar to the volunteers' range of motion. It was observed that the THOR NT with the new shoulder did not slide out of the shoulder belt during a far-side collision. The performance of the new shoulder was reasonably repeatable and stable during both the static tests and the sled tests. CONCLUSION: A new shoulder for the THOR NT has been designed and developed, and data from static range of motion tests and sled tests indicate that the new shoulder complex has the potential to function in a more human-like manner on the THOR dummy.     

Impact on sward composition and stock performance of grazing Molinia-dominant grassland

A comparative experiment was conducted to test the extent to which grazing of rank Molinia caerulea-dominated grassland increases botanical diversity and improves animal performance. The study was carried out on an area of under-grazed Molinia-dominant pasture that had not been stocked for 20 years. Three treatments were compared from 2001 until 2008: (1) no grazing, (2) grazing by Welsh Mountain sheep and (3) grazing by Welsh Black heifers. Patterns of change in sward surface composition across the grazing season were consistent with greater consumption of Molinia by the cattle, but there was little evidence of management regime influencing changes in sward composition year-on-year. There was a significant effect of year on animal performance (P < 0.001). Although the growth rates of the heifers improved over the course of the first three years of the experiment, this performance was not sustained. In contrast, any weight changes for the sheep were positive. The results highlight the slow pace of change within upland swards, and the need to develop site-specific grazing guidelines.