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Specific Weight (specific + weight)
Selected AbstractsFire hazard evaluation of thermoplastics based on analytic hierarchy process (AHP) methodFIRE AND MATERIALS, Issue 5 2010Baogang Yu Abstract Combustibility performance of 14 compositions including five main thermoplastics (polycarbonate (PC), polypropylene (PP), high impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS) and poly (vinyl chloride) (PVC)) was tested by cone calorimeter. The fire growth index, total heat release amount index, total smoke release amount index and toxicity product index were calculated, based on which an index system for evaluating fire hazard was set up. All factors in this index system had been analyzed by the analytic hierarchy process, and the specific weight for each factor had been determined. Then fire hazard of thermoplastics was evaluated considering integrated fire hazard index. The results show that fire hazards of HIPS-phosphate fire retardant (PFR), PVC-non-flame retardant, ABS-brominated flame retardant (BFR) and PC/ABS-PFR are higher than PC-BFR and PP-non-halogenated flame retardant. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ceramic Matrix Composites: A Challenge in Space-Propulsion Technology ApplicationsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2005Stephan Schmidt Various technology programs in Europe are concerned, besides developing reliable and rugged, low-cost, throwaway equipment, with preparing for future reusable propulsion technologies. One of the key roles for realizing reusable engine components is the use of modern and innovative materials. One of the key technologies that concerns various engine manufacturers worldwide is the development of fiber-reinforced ceramics,CMCs (ceramic matrix composites). The advantages for the developers are obvious,the low specific weight, the high specific strength over a large temperature range, and their great damage tolerance compared with monolithic ceramics make this material class extremely interesting as a construction material. Over the past few years, the EADS-ST Company (formerly DASA) has, together with various partners, worked intensively on developing components for hypersonic engines and liquid rocket propulsion systems. In the year 2000, various hot-firing tests with subscale (scale 1:5) and full-scale nozzle extensions were conducted. In this year, a further decisive milestone was achieved in the sector of small thrusters, and long-term tests served to demonstrate the extraordinary stability of the C/SiC material. Besides developing and testing radiation-cooled nozzle components and small-thruster combustion chambers, EADS-ST worked on the preliminary development of actively cooled structures for future reusable propulsion systems. In order to get one step nearer to this objective, the development of a new fiber composite was commenced within the framework of a regionally sponsored program. The objective here is to create multidirectional (3D) textile structures combined with a cost-effective infiltration process. Besides material and process development, the project also encompasses the development of special metal/ceramic and ceramic/ceramic joining techniques as well as studying and verifying nondestructive investigation processes for the purpose of testing components. [source] The effect of the time and mode of application of gibberellic acid and inhibitors of gibberellin biosynthesis on the dormancy of potato tubers grown from true potato seedJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2007Alexios A Alexopoulos Abstract Gibberellic acid (GA3) and inhibitors of gibberellin biosynthesis (daminozide and chlormequat chloride) were applied to the foliage of potato plants grown from true seed (TPS) either once at two stages of plant development, 40 and 60 days after transplantation (DAT), or repeatedly at 10 day intervals starting from the same growth stages. When GA3 was applied towards the end of the vegetative cycle (either singly 60 DAT or repeatedly from the same date), it induced rapid breakage of tuber dormancy, a reduction in specific weight, a higher rate of respiration and increased weight loss during storage. Single applications of GA3 early in the vegetative cycle (40 DAT) had no effect on the weight loss and specific weight of tubers during storage, whereas repeated foliar applications of GA3 starting from the same stage resulted in the formation of tubers with a low specific weight and a high rate of weight loss during storage. However, the tubers from these treatments did not break dormancy uniformly, and, although in the early stages of storage they exhibited a high rate of respiration, this declined to the level of the control (no growth regulator applied). Although daminozide and chlormequat chloride did not affect the duration of tuber dormancy and had little or no effect on any of the other metabolic indicators studied, gibberellin is nevertheless implicated in dormancy breakage, and its application late in the growth cycle may be of practical value in cases where tubers are required for planting soon after harvest. Overall, tubers from TPS respond to plant growth regulator treatment in a similar way to those from plants grown from seed tubers. Copyright © 2007 Society of Chemical Industry [source] The effects of irrigation, nitrogen fertilizer and grain size on Hagberg falling number, specific weight and blackpoint of winter wheatJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2004Matthew P Clarke Abstract The effects of irrigation and nitrogen (N) fertilizer on Hagberg falling number (HFN), specific weight (SW) and blackpoint (BP) of winter wheat (Triticum aestivum L) were investigated. Mains water (+50 and +100 mm month,1, containing 44 mg NO3, litre,1 and 28 mg SO42, litre,1) was applied with trickle irrigation during winter (17 January,17 March), spring (21 March,20 May) or summer (24 May,23 July). In 1999/2000 these treatments were factorially combined with three N levels (0, 200, 400 kg N ha,1), applied to cv Hereward. In 2000/01 the 400 kg N ha,1 treatment was replaced with cv Malacca given 200 kg N ha,1. Irrigation increased grain yield, mostly by increasing grain numbers when applied in winter and spring, and by increasing mean grain weight when applied in summer. Nitrogen increased grain numbers and SW, and reduced BP in both years. Nitrogen increased HFN in 1999/2000 and reduced HFN in 2000/01. Effects of irrigation on HFN, SW and BP were smaller and inconsistent over year and nitrogen level. Irrigation interacted with N on mean grain weight: negatively for winter and spring irrigation, and positively for summer irrigation. Ten variables derived from digital image analysis of harvested grain were included with mean grain weight in a principal components analysis. The first principal component (,size') was negatively related to HFN (in two years) and BP (one year), and positively related to SW (two years). Treatment effects on dimensions of harvested grain could not explain all of the effects on HFN, BP and SW but the results were consistent with the hypothesis that water and nutrient availability, even when they were affected early in the season, could influence final grain quality if they influenced grain numbers and size. Copyright © 2004 Society of Chemical Industry [source] Millimetre-scale bubble-like dielectric elastomer actuatorsPOLYMER INTERNATIONAL, Issue 3 2010Federico Carpi Abstract Hydrostatic coupling has recently been reported as a means to improve the versatility and safety of electromechanical actuators based on dielectric elastomers (DEs). Hydrostatically coupled DE actuators rely on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load. The work reported here was aimed at developing millimetre-scale bubble-like versions of such transducers. Silicone-made oil-filled actuators were manufactured as both single units and arrays of parallel elements. Bubbles had a base diameter of 6 mm and were driven up to a voltage of 2.25 kV, applied across a silicone film with a thickness of 42 µm. Active relative displacements and stresses up to 18% and 2.2 kPa, respectively, were recorded with static driving. Dynamic investigations reported a ,3 dB bandwidth of the order of 100 Hz and a resonance frequency of about 250 Hz. Millimetre-scale hydrostatically coupled DE actuators might play a useful role in several fields of application. Among them, we are currently exploring novel tactile displays and cutaneous stimulators, made of wearable, distributed and flexible devices. Although further miniaturization is required for high-resolution uses, this technology holds promise to properly combine performance with safe and compliant interfaces with users, low specific weight, no acoustic noise and low cost. Copyright © 2009 Society of Chemical Industry [source] Savannah woodland vegetation in the South-East District of South Australia: the influence of evaporative aerodynamics on the foliage structure of the understorey invaded by introduced annualsAUSTRAL ECOLOGY, Issue 6 2000R. L. SPECHT Abstract Evaporative aerodynamics determine the foliage projective cover of the understorey of perennial tussock grasses and associated perennial herbs in the savannah woodland dominated by Eucalyptus camalduknsis on gleyed podsolic soils in the Mediterranean climate of the South-East District of South Australia. By the mid 1940s, winter-spring evapotranspiration from the ,thin' leaves (with low leaf specific weight) of introduced annual plants was depleting surface soil water and thus reducing the annual growth of the summer-growing savannah understorey; perennial herbs between the tussock grasses were the first to succumb to this competition. During spring, the percentage of the ground covered by the savannah understorey was increased by 10% in the subhumid zone to 30% in the humid zone as the pre-European perennial herbs between the tussock grasses were replaced by introduced annuals. Application of phosphatic fertilizer to the understorey increased the growth of introduced annuals, which formed a dense stratum during their winter-spring growing season, increasing evapotranspiration and leading eventually to the extinction of the native perennial grasses. When the savannah understorey, invaded by introduced annuals in the mid-1940s, was converted to improved pasture, the percentage of ground covered by the seasonal foliage was increased by 20,30%; 100% coverage of overlapping foliage resulted in the humid zone. [source] Extensions of the 3-Dimensional Plasma Transport Code E3DCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2004A. Runov Abstract One important aspect of modern fusion research is plasma edge physics. Fluid transport codes extending beyond the standard 2-D code packages like B2-Eirene or UEDGE are under development. A 3-dimensional plasma fluid code, E3D, based upon the Multiple Coordinate System Approach and a Monte Carlo integration procedure has been developed for general magnetic configurations including ergodic regions. These local magnetic coordinates lead to a full metric tensor which accurately accounts for all transport terms in the equations. Here, we discuss new computational aspects of the realization of the algorithm. The main limitation to the Monte Carlo code efficiency comes from the restriction on the parallel jump of advancing test particles which must be small compared to the gradient length of the diffusion coefficient. In our problems, the parallel diffusion coefficient depends on both plasma and magnetic field parameters. Usually, the second dependence is much more critical. In order to allow long parallel jumps, this dependence can be eliminated in two steps: first, the longitudinal coordinate x3 of local magnetic coordinates is modified in such a way that in the new coordinate system the metric determinant and contra-variant components of the magnetic field scale along the magnetic field with powers of the magnetic field module (like in Boozer flux coordinates). Second, specific weights of the test particles are introduced. As a result of increased parallel jump length, the efficiency of the code is about two orders of magnitude better. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Vegetation structure and biodiversity along the eucalypt forest to rainforest continuum on the serpentinite soil catena in a subhumid area of Central Queensland, AustraliaAUSTRAL ECOLOGY, Issue 3 2006RAY L. SPECHT Abstract The deep lateritic earths that cap the serpentinite outcrop in the Rockhampton , Marlborough area on the Tropic of Capricorn in Central Queensland have been eroded to expose the underlying ultramafic rock. Water-holding capacity of these nutrient-poor soils increases in a gradient from the skeletal soils to the deep lateritic earths and results in a continuum of structural formations from open-woodland to woodland to open-forest. A couple of closed-forest (rainforest) stands have developed where seepage into Marlborough Creek occurs throughout the year. Aerodynamic fluxes (frictional, thermal and evaporative) in the atmosphere as it flows over and through the vegetation influence the annual foliage growth in all strata in the continuum from skeletal soils to deep lateritic earths. The lateral growth of each plant is abraded so that the sum of the foliage projective covers of overstorey (FPCo) and understorey (FPCu) strata , that is ,(FPCo + FPCu) , remains constant throughout the serpentinite soil catena. As more water becomes available in the soil catena, the mineral nutrient levels in overstorey leaves increase, making developing leaves more vulnerable to insect attack. Although the number of leaves produced annually on each vertical foliage shoot in the overstorey increases along the soil-water gradient, ,(FPCo + FPCu) remains constant in all stands. The carbon isotope ratios (a measure of stomatal resistance) and leaf specific weights (LSWs) (a measure of the proportion of structural to cytoplasmic content in a leaf) of overstorey and understorey strata, however, are constant throughout the continuum. The well-watered rainforest pockets , where seepage occurs , form the end point of this serpentinite continuum. LSWs and carbon isotope ratios of the canopy trees are similar to those in the sheltered understorey in the eucalypt communities. A gradient of foliage attributes is observed from evergreen canopy trees (12 m) to subshrubs (2 m) in the sunlit life forms that compose the complex structure of the rainforest stands in the humid to subhumid climate of Central Queensland. As alpha diversity (number of species per hectare) is correlated with annual shoot growth per hectare, species richness along the serpentinite continuum is almost half that of nearby plant communities on medium-nutrient soils. The one to two eucalypt species per hectare are about a tenth of the number recorded on adjacent medium-nutrient soils. [source] | ||||||||||