Self Piercing Riveting for Metal-Polymer Joints

Self-Piercing Riveting (SPR) is a sheet metal joining technique based on the insertion of a rivet into two or more sheets, with no preparatory hole. This process has gained wide diffusion in the automotive industry, due to the increasing use of materials alternative to steel, that are difficult or impossible to join with traditional techniques. In particular, polymeric materials are becoming increasingly used, due to their favorable weight/strength ratio. This paper reports the results of experimental investigations, aimed at identifying the variables affecting the mechanical characteristics of mixed metal-plastic joints. A statistic model for the optimization of the geometrical parameters has been computed. The paper demonstrates that self-piercing riveting appears competitive for metal/polymer junction. The results analyzed in light of statistical techniques show that some geometrical parameters affect joint performance more than others and can therefore be used as independent variables for joint performance optimizatio

Guiding and reflecting light by boundary material

We study effects of finite height and surrounding material on photonic crystal slabs of one- and two-dimensional photonic crystals with a pseudo-spectral method and finite difference time domain simulation methods. The band gap is shown to be strongly modified by the boundary material. As an application we suggest reflection and guiding of light by patterning the material on top/below the slab.Comment: 12 pages, 7 figure

Method for increasing the energy efficiency of wirelessly networked ambulatory health monitoring devices

In-home healthcare applications that use wearable devices ordinarily have strict power constraints due to the small size of the battery in the device. The power constraints are a key driver of research to develop new methods for improving the energy efficiency of ambulatory health monitoring devices. The radio-communication components typically consume a large proportion of the available energy in systems such as these. Given that radio transmissions use far more power than on-board processing, it is proposed that energy can be conserved by performing fall detection at the node. The proposed algorithm is intended to be performed at the node and provide a suitable balance between power consumption and detection accuracy. The research and prototype system described in this article focuses on wearable fall detection devices to be used elderly people who are living in non-hospital settings, and discusses considerations arising from the development of a prototype system. The outcomes of the system design and development process are discussed, and conclusions are drawn concerning the potential of the method to improve the energy efficiency of fall detection systems

A Numerical Study on Temperature Distribution of Line Heated Anisotropic Carbon Fiber Composites

Earlier we have described the various uses of infrared line scanner based thermal nondestructive testing equipment [1]. Time constants of measurements made with these kind of equipment are very suitable for testing carbon fiber composites. Scanning a line heat source over a sample surface causes a nonuniform temperature distribution in the sample. In addition to the heat flow normal to the surface, lateral heat flow exists in the surface plane. In the case of carbon fiber composites with a specific oriented structure, the surface temperature distributions depend on the direction where the line source moves. Generally, this is true of any sample having anisotropic thermal conductivity. In oriented carbon fiber composites the bulk thermal conductivity can be considered anisotropic, because the heat transfer in the composite is different in the direction of the fibers compared to perpendicular directions [2,3]. Varis et al. have discussed these phenomenon briefly with the testing of carbon fiber tubes using numerical methods [4]. Here, we represent a more detailed numerical analysis of the effects of line heating on a sample having anisotropic thermal conductivity

Climate-driven interannual variability of water scarcity in food production potential: A global analysis

Interannual climatic and hydrologic variability has been substantial during the past decades in many regions. While climate variability and its impacts on precipitation and soil moisture have been studied intensively, less is known on subsequent implications for global food production. In this paper we quantify effects of hydroclimatic variability on global "green" and "blue" water availability and demand in global agriculture, and thus complement former studies that have focused merely on long-term averages. Moreover, we assess some options to overcome chronic or sporadic water scarcity. The analysis is based on historical climate forcing data sets over the period 1977-2006, while demography, diet composition and land use are fixed to reference conditions (year 2000). In doing so, we isolate the effect of interannual hydroclimatic variability from other factors that drive food production. We analyse the potential of food production units (FPUs) to produce a reference diet for their inhabitants (3000 kcal cap-1 day -1, with 80% vegetal food and 20% animal products). We applied the LPJmL vegetation and hydrology model to calculate the variation in green-blue water availability and the water requirements to produce that very diet. An FPU was considered water scarce if its water availability was not sufficient to produce the diet (i.e. assuming food self-sufficiency to estimate dependency on trade from elsewhere). We found that 24% of the world's population lives in chronically water-scarce FPUs (i.e. water is scarce every year), while an additional 19% live under occasional water scarcity (water is scarce in some years). Among these 2.6 billion people altogether, 55% would have to rely on international trade to reach the reference diet, while for 24% domestic trade would be enough. For the remaining 21% of the population exposed to some degree of water scarcity, local food storage and/or intermittent trade would be enough to secure the reference diet over the occasional dry years

Comparison of novel fungal mycelia strains and sustainable growth substrates to produce humidity-resistant biocomposites

Fungal mycelia are versatile, highly productive and sustainable sources for biocomposites to replace conventional plastics. However, with only very few fungal strains that have been characterized, numerous strains still remain unexplored as potential competitors against traditional non-biodegradable materials. Moreover, the functionality of mycelium composites at commonly occurring, challenging ambient conditions such as changing humidity and temperature is not well characterized. Here we evaluated the properties of the fungal composite material produced by novel fungal strains, including Trichoderma asperellum and Agaricus bisporus, grown on oat husk and rapeseed cake after oil pressing. The results showed that the mycelium composites were hydrophobic and strong, particularly when grown on rapeseed cake. A. bisporus grown on rapeseed cake exhibited increased stiffness after humidity was successively increased and decreased. The moisture-resistance of these novel mycelium composites is encouraging for novel sustainable material solutions.Peer reviewe

Conventional and organic cropping systems at Suitia II: Crop growth and yield

Crop yields between 1982 and 1988 are reported here as a part of a cropping system experiment carried out at Suitia, Southern Finland. The soil was silty clay. There were four conventional and four organic systems: conventional cropping systems for barley monoculture, cereal production, diverse plant production, or a cattle farm, and organic cropping systems either for plant production with or without composting, or for cattle farms with or without composting. The crop sequences were fixed by six-year rotations, carried out in two phases. There were great differences in yields between the years, and the organic cropping systems were more negatively affected by poor growing conditions than the conventional ones. In the organic systems, the barley yields in 1985 and in 1988 were 25 % of the yields obtained from conventional stands, when the latter yielded about 3 t/ha. In better years, barley in the organic plant production yielded 50 % of the yield obtained in conventional barley monoculture (6 t/ha). It was not possible to differentiate between the effects of two different causes the preceeding crop and annual variation. The yields obtained with ’organic’ winter wheat and oats (+ Vicia faba) were 40 % of those from the respective conventional pure stands. The clover-grass leys of the organic systems yielded as much as the conventional grass leys until they were destroyed by water and the resulting ice cover during winter. Compared to those of ‘conventional’ system, the ‘organic’ system gave annual mean yields of potato varying from 37 % of the 16 t/ha obtained conventionally to 48% of the 21 t/ha obtained conventionally. Barley variety was found to interact with cropping system in 1988, a year characterised by draught stress. In 1989, in a separate trial carried out on the same field, an interaction between soil wetness (location) and cropping system was observed. Wetness of soil in winter seemed to interfere more severely in the organic system than in the conventional one. Because the uncontrolled variation of the field itself as to topography and drainage makes the comparisons between the organic and the conventional systems somewhat biased and unreliable, these results should not be generalised to cover the overall question of yield level in organic cropping

A New Method for Combined Hyperventilation and Hypoxia Training in a Tactical Fighter Simulator

Physiological episodes are an issue in military aviation. Some non-pressure-related in-flight symptoms are proved to be due to hyperventilation rather than hypoxia. The aim of this study was to validate a new training method provoking hyperventilation during normobaric hypoxia (NH) training in an F/A-18 Hornet simulator. METHODS: In a double-blind setting, 26 fighter pilots from the Finnish Air Force performed 2 setups in a WTSAT simulator in randomized order with full flight gear. Without the pilot's knowledge, 6% O2 in nitrogen or 6% O2 + 4% CO2 in nitrogen was turned on. Ventilation (VE) was measured before, during, and after hypoxia. SpO2 and ECG were monitored and symptoms documented. The subjects performed a tactical identification flight until they recognized symptoms of hypoxia. Thereafter, they performed hypoxia emergency procedures with 100% O2 and returned to the base with a GPS malfunction and executed an instrument landing system (ILS) approach with the waterline HUD mode evaluated by the flight instructor on a scale of 1 to 5. RESULTS: Ventilation increased during normobaric hypoxia (NH) from 12 L · min−1 to 19 L · min−1 at SpO2 75% with 6% O2, and from 12 L · min−1 to 26 L · min−1 at SpO2 77% with 6% O2 + 4% CO2. ILS flight performance was similar 10 min after combined hyperventilation and hypoxia (3.1 with 6% O2 + 4% CO2 and 3.2 with 6% O2). No adverse effects were reported during the 24-h follow-up. DISCUSSION: Hyperventilation-provoking normobaric hypoxia training is a new and well-tolerated method to meet NATO Standardization Agreement hypoxia training requirements

Planck-LFI radiometers' spectral response

The Low Frequency Instrument (LFI) is an array of pseudo-correlation radiometers on board the Planck satellite, the ESA mission dedicated to precision measurements of the Cosmic Microwave Background. The LFI covers three bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central frequency. The characterization of the broadband frequency response of each radiometer is necessary to understand and correct for systematic effects, particularly those related to foreground residuals and polarization measurements. In this paper we present the measured band shape of all the LFI channels and discuss the methods adopted for their estimation. The spectral characterization of each radiometer was obtained by combining the measured spectral response of individual units through a dedicated RF model of the LFI receiver scheme. As a consistency check, we also attempted end-to-end spectral measurements of the integrated radiometer chain in a cryogenic chamber. However, due to systematic effects in the measurement setup, only qualitative results were obtained from these tests. The measured LFI bandpasses exhibit a moderate level of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins

Evaluating the impact of pyrethroid insecticide resistance on reproductive fitness in Sitobion avenae

Resistance to insecticides used to control pests is an issue of increasing concern for agriculture. The grain aphid, Sitobion avenae, is a pest of cereals and grasses worldwide, and one of growing concern due to the evolution of resistance to certain insecticides. Resistance confers benefits to insects by enabling them to survive exposure to insecticide compounds; however, the mutations conferring resistance may also penalise the insect in pesticide-free environments due to fitness costs associated with the new phenotype. Here we tested the hypothesis of a reproductive penalty linked to the knockdown resistance mutation (kdr) to pyrethroid insecticides. The mutation occurs predominantly in a single SA3 clone. To date, only heterozygous-resistant forms (kdr-SR) have been detected in populations in Ireland and the UK, and this suggests that a fitness penalty may preclude the formation of both male and female heterozygous-resistant sexual forms. By designing an experiment which included a resistant and a non-resistant clone, we were able to simulate reduced daylight and temperature conditions which, in nature, trigger sexual reproduction and therefore study the responses of each clone. This allowed us to detect the switch from asexual females to sexual females and males and report on the conditions associated with the production of sexual forms. The results showed that both aphid clones were able to produce sexual forms with no difference in the onset of sexual reproduction, although reproductive strategies differed between clones. The later onset of male forms in the SA3 clone may decrease the likelihood of mating interactions to create fully resistant (kdr-RR) genotypes and this may constitute a fitness penalty due to pyrethroid resistance