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Selective Laser Melting (SLM) – as one of a number of additive manufacturing techniques – is a promising method for the manufacturing of complex structures and may bring about significant improvements in the context of custom-made designs and lightweight constructions. However, the complex multiphysical processes occurring during SLM necessitates the establishment of appropriate constitutive and process models in order to quantitatively predict the properties of the final workpiece. In particular, the accurate determination of process-induced eigenstresses is a challenging yet important task. In this work, a constitutive modelling framework stemming from phase transformations in shape memory alloys is adopted to the modelling of the changes of state during SLM. This model is based on energy densities and energy minimisation in general and specifically serves as a basis for further enhancements such as the consideration of multiple solid phases of the underlying material. This is particularly considered important due to the fact that the cooling rates during SLM are heterogeneously distributed and that thus different solid phases may form out of the molten material pool. As a first step, the present overall model comprises three phases of the material, namely powder, molten, and re-solidified material. The thermomechanically fully coupled Finite-Element-based process model incorporates approaches for, e.g., the laser beam impact zone and the layer construction model.

This study is the first to characterize the impact properties of a new hybrid composite made with woven carbon fibres plus unidirectional (i.e. Type A) or cross-ply (i.e. Type B) flax fibres in an epoxy matrix. A pendulum impact tester applied a range of impact energies (5–40 J) to a series composite plates, which were assessed using photographic, thermographic, and geometric techniques. The Type B composite had better impact performance vs the Type A as indicated by lower absorbed energies, higher penetration energy, smaller crack lengths, smaller indentation depths, smaller damage areas, lower temperature rises in the impact zone vs applied impact energy, and higher impact strength. Both the Type A and B hybrid composites had superior impact properties compared to pure flax fibre-reinforced epoxy composites reported in prior literature, suggesting that hybridization using synthetic and natural fibres can be done successfully.

In this study, we evaluated the emission rates of ambient fine particulate matter (PM2.5) mass, particle number (PN), and black carbon (BC) from sources at the Ports of Los Angeles (POLA) and Long Beach (POLB), including ships, cargo-handling equipment (CHE), locomotives, and heavy-duty vehicles (HDVs) operating at the ports terminal, as well as from vehicles on the nearby freeways. We also evaluated the impact of these emissions on local air quality (i.e., within the “impact zone” of POLA and POLB), and on the air quality in the Los Angeles County. The impact zone of POLA and POLB was defined as the area confined by the I-105, I-110, and I-710 freeways, and the ports’ ship terminals. At the local scale, emission rates were dominated by the sources at the ports (i.e., ships, locomotives, CHE, and HDVs operating at the ports), with overall PM2.5, PN, and BC emission rates of 97.8 ± 9.8 kg day−1, 91.6 ± 10.6 × 1019 particles day−1, and 60.3 ± 5.3 kg day−1, respectively. Emission rates from sections of the abovementioned nearby freeways were considerably lower, with corresponding values of 8.4 ± 3.8 kg day−1 for PM2.5, 2.4 ± 1.3 × 1019 particles day−1 for PN, and 2.0 ± 1.6 kg day−1 for BC. However, at the scale of Los Angeles County, the emission rates from total freeways across the Los Angeles County were significantly higher than those of the POLA and POLB, with overall values of 506.9 ± 20.3 kg day−1 for PM2.5, 1.9 ± 0.4 × 1021 particles day−1 for PN, and 119.4 ± 10.2 kg day−1 for BC. Our findings illustrate the major impact of emissions from POLA and POLB on the air quality of communities in the vicinity of the port. However, across the Los Angeles County as a whole, freeway emissions become the most important source of PM2.5, PN, and BC emissions, with emission rates 2–5 times higher than those of source categories at POLA and POLB.

This study uses the opening of the new Circle Line (CCL) in Singapore as a natural experiment to test the effects of urban rail transit networks on non-landed private housing values. We use a network distance measure and a local-polynomial-regression approach to identify the CCL impact zone with discontinuity in housing price gradient between a treatment zone and a control zone. We then estimate the spatial difference-in-differences models that account for spatial autocorrelation in housing price changes in the two zones “before and after” the opening of the CCL. We find that the opening of the CCL increases housing value in the treated neighborhoods located within the 600-metre network distance from the new CCL stations by approximately 8.6%, relative to other properties in the untreated neighborhoods controlling for heterogeneities in housing attributes and local amenities, and spatial and temporal fixed effects. We find significant “anticipation” effects as early as 1 year prior to the opening of the CCL line, but the effects diminish closer to the actual opening date. The results imply that the inter-dependent spatial structure between the treated and the untreated neighborhoods, if neglected, may lead to over-estimation of the capitalization effects of the new transit lines on housing values.

In this paper, the analysis of technical requirements (TR) for the development of modern space launch vehicles (LV) with main liquid rocket engines (LRE) is fulfilled in relation to the anthropogenic impact decreasing. Factual technical characteristics on the example of a promising type of rocket “Soyuz-2.1.v.” are analyzed. Meeting the TR in relation to anthropogenic impact decrease based on the conventional design approach and the content of the onboard system does not prove to be efficient and leads to depreciation of the initial technical characteristics obtained at the first design stage if these requirements are not included. In this concern, it is shown that the implementation of additional active onboard de-orbiting system (AODS) of worked-off stages (WS) into the onboard LV stages systems allows to meet the TR related to the LV environmental characteristics, including fire-explosion safety. In some cases, the orbital payload mass increases.

Artisanal gold mining (galamsey) and cocoa farming are essential sources of income for local populations in Ghana. Unfortunately the former poses serious threats to the environment and human health, and conflicts with cocoa farming and other livelihoods. Timely and spatially referenced information on the extent of galamsey is needed to understand and limit the negative impacts of mining. To address this, we use multi-date UK-DMC2 satellite images to map the extent and expansion of galamsey from 2011 to 2015. We map the total area of galamsey in 2013 over the cocoa growing area, using k-means clustering on a cloud-free 2013 image with strong spectral contrast between galamsey and the surrounding vegetation. We also process a pair of hazy images from 2011 and 2015 with Multivariate Alteration Detection to map the 2011–2015 galamsey expansion in a subset, labelled the change area. We use a set of visually interpreted random sample points to compute bias-corrected area estimates. We also delineate an indicative impact zone of pollution proportional to the density of galamsey, assuming a maximum radius of 10 km. In the cocoa growing area of Ghana, the estimated total area of galamsey in 2013 is 27,839 ha with an impact zone of 551,496 ha. In the change area, galamsey has more than tripled between 2011 and 2015, resulting in 603 ha of direct encroachment into protected forest reserves. Assuming the same growth rate for the rest of the cocoa growing area, the total area of galamsey in 2015 is estimated at 43,879 ha. Galamsey is developing along most of the river network (Offin, Ankobra, Birim, Anum, Tano), with downstream pollution affecting both land and water.

Fibre Metal Laminates have been manufactured by liquid moulding. Flow paths have been drilled to enable the impregnation through the aluminium sheets. The effect of these holes on the low velocity impact behaviour has been studied. Damage mechanisms, dissipated energy and peak force of drilled samples have been compared to those of reference samples without holes. Results show that the presence of the holes has no effect on the performance of the plate and that the internal damage is confined to the surrounding of the impact zone. When the holes are inside the impact contact zone cracks in aluminium sheets propagate through the holes, but their effect is mitigated by the fibre bridging mechanism. Holes located out of the impact contact zone have no effect in the damage mechanisms.

The periodic region with a helicoidal structure and the impact zone with a herringbone structure of the mantis shrimp’s dactyl club, which makes it excellent in energy absorption. This biological structure gives us effective methods for making novel composite structures. In this paper, a dactyl-inspired sinusoidal-corrugated helicoidal sandwich-structural honeycomb (DSHSH) was manufactured with unidirectional basalt fiber and aluminum honeycomb based on periodic region and impact region of dactyl club. The DSHSH was compared with dactyl-inspired sinusoidal-corrugated plain-woven skin sandwich-structural honeycomb (DSPSH) and dactyl-inspired sinusoidal-corrugated unidirectional skin sandwich-structural honeycomb (DSUSH), dactyl-inspired helicoidal sandwich-structural honeycomb (DHSH), traditional plain-woven skin sandwich-structural honeycomb (TPSH), and traditional unidirectional skin sandwich-structural honeycomb (TUSH) in tests of impact and flexrual. The results exhibited that DSHSH that simulates multi-structures (periodic and impact regions) significantly improves peak load and energy absorption capabilities.

In this paper, some of the important defeating mechanisms of the high hardness perforated plates against 7.62 x 54 armor piercing ammunition were investigated. The experimental and numerical results identified three defeating mechanisms effective on perforated armor plates which are the asymmetric forces deviates the bullet from its incident trajectory, the bullet core fracture and the bullet core nose erosion. The initial tests were performed on the monolithic armor plates of 9 and 20 mm thickness to verify the fidelity of the simulation and material model parameters. The stochastic nature of the ballistic tests on perforated armor plates was analyzed based on the bullet impact zone with respect to holes. Various scenarios including without and with bullet failure models were further investigated to determine the mechanisms of the bullet failure. The agreement between numerical and experimental results had significantly increased with including the bullet failure criterion and the bullet nose erosion threshold into the simulation. As shown in results, good agreement between Ls-Dyna simulations and experimental data was achieved and the defeating mechanism of perforated plates was clearly demonstrated. (C) 2014 Elsevier Ltd. All rights reserved.

Exurban development represents a potential threat to wildlife communities and ecological integrity in rural landscapes worldwide and recent work has suggested that its ecological impacts can be similar to those associated with more characteristically urban development patterns. Despite the large scope and rapid pace of exurbanization, understanding of its ecological consequences is incomplete and most North American research has occurred in the western United States. The ecological impact zone denotes the area surrounding a home which should be considered affected habitat and has been shown to be demonstrably larger than the actual footprint of homes and lawns. We conducted a study to determine whether an impact zone of 180 m identified for a shrub-oak community in the Rocky Mountain west was applicable in an eastern, closed forest system. We sampled bird communities at the forest/lawn edge of exurban homes, and at 200- and 400-m in surrounding forest and modeled occupancy at increasing distances from residential structures for human-adapted, human-sensitive, and neutral species. Occupancy rates of human-adapted and human-sensitive species were different (36% higher and 26% lower, respectively) at points near homes versus those in surrounding forest. Our findings indicate a similarity in the effects of exurban homes on avian communities and the size of the ecological impact zone in these structurally different eastern and western North American landscapes. This similarity suggests the possibility that human behaviors associated with exurban homes may play a larger role in shaping avian community characteristics nearby than do habitat alterations created by construction and clearing.

Ionomers are known to exhibit a unique self-healing capacity under ballistic impact by sharp projectiles. As the kinetics of the event is such that a systematic exploration of the relevant mechanisms are impossible, a novel quasi-static test method was developed to identify the relevant processes. The method mimics the self-healing process by pulling a pre-heated disk-shaped object through the ionomeric polymer rapidly and in a controlled manner. The advantage of this method over other reported methods is that the penetrant is completely removed from the impact zone and thus does not interfere with the self-healing process. Due to the controlled manner of the test, quantitative information can be obtained which allows for further mechanistic studies. The two key parameters which optimise the mimicry of the healing process investigated are (1) the localised heating of the impact region and (2) the speed of the impact. Both variables have been shown to play an important role in healing from both a macroscopic and micro-structural perspective.

The monitoring of the odor annoyance generated by a landfill area is difficult, since it is a multi-area-sources problem, with a discontinuous odor emission. This paper proposes an adaptation of the method of sniffing team campaigns to the particular case of fresh waste odors. The method is based on the field determination of odor perception points, followed by data processing with a bi-Gaussian-type model, adapted to handle the odors. In a first step, field observers delineate the region in which odor impact is experienced and then the emission rate is manipulated in a dispersion model until the predicted size of the impact zone matches that observed in the field. In a second step the adjusted emission rate is entered into the model to calculate the percentiles corresponding to the average annoyance zone. The originality of the proposed method is the introduction of all observation points and of all recorded meteorological data into the model. The paper discusses the method limitations and the errors induced on the results, i.e. the odor emission rate and the percentile lines (or iso-concentration lines) which are used to describe the odor concentrations on a map of the surroundings of the plant. The proposed method proves to be reliable for diffuse sources, such as landfill areas. The obtained results are coherent with other results found in the literature with other techniques.

The sputtering characteristics of Cu crystal targets with stepped surfaces have been examined with classical dynamics computer simulations. The predicted yields, angular distributions, statistical properties and spatial origins of sputtered atoms are reported. The three targets investigated were: a Cu(1 0 0) surface with a monatomic step, denoted Cu(1 0 0)-(S); the Cu(29, 1, 1) surface; and the Cu(20, 1, 1) surface. A 3 keV Ar projectile with a glancing angle of incidence (ϕ=5°) was employed. The surface structures of the targets consist of (1 0 0) terraces separated by monatomic (1 1 1) steps. For the Cu(29, 1, 1) and Cu(20, 1, 1) targets, the spatial distributions of sputtered atom lattice sites display a bimodal character. The peaks of the distributions are localised in the vicinity of the (1 1 1) steps which lie behind the primary zone of projectile impact. This pattern of sputtering can be understood with the help of a two-dimensional description of the projectile–target interaction. Projectile–surface atom close encounters are possible when projectiles undergo direct collisions with atoms at the leading terrace edge on their approach to the surface, or when projectiles reflected from the primary impact zone are focussed onto edge atoms in the adjacent terrace. For the Cu(1 0 0)-(S) target, only the first mechanism is feasible.

Testimonies disclosed that a 44-year-old pedestrian was struck head-on by a truck while she was roaming on the motorway; at the time of collision, the truck was travelling at a speed of about 90 km/h. In the second phase of the collision, the pedestrian was projected about 100 m before her body was run over by the truck and then by a car. The autopsy revealed extensive mutilations, making it impossible to verify the testimonies of witnesses to the collision as regards the pedestrian's position at the moment of the first impact. However, the reports produced by the technical expert and the forensic pathologist were able to confirm the testimonies, based on an impact zone on the front panel of the cab of the truck, where part of the pedestrian's face was reproduced like a "modern holy shroud".

The current radioecological situation around the reprocessing plant “Mayak”, which was constructed more than 40 years ago for the production of plutonium for military purposes, is overviewed. The following topics are considered: Karachay Lake; artificial water reservoirs contaminated by radionuclides; solid radioactive wastes and their vitrification. Some new approaches, methods and tools developed at the Vernadsky Institute of the Russian Academy of Sciences for determination of different radionuclides in various environmental samples from the impact zone of the facility are discussed. Data on distribution, occurrence forms and migration processes of90Sr,137Cs,237Np,239Pu and241Am in aquatic and terrestrial ecosystems are presented.

The effects of material nonlinearities on response spectra resulting from the impact of a commercial aircraft on the secondary containment of a BWR reactor are investigated. A unite element model taking into account concrete cracking and crushing and steel yielding is used for the analysis. The results show that, for the design considered here, no reduction of the response spectra due to material nonlinearity in the impact zone can be expected. As a matter of fact, an amplification results close to the impact area.