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Physical Size (physical + size)
Selected AbstractsSize-dependent species-area relationships in benthos: is the world more diverse for microbes?ECOGRAPHY, Issue 3 2002Andrey I. Azovsky Using original and literature data on species richness, I compared the species-area relations for 5 different size classes of the Arctic benthos: macrofauna sensu lato, polychaetes, nematodes, ciliates and diatom algae. The data pool covered a wide range of areas from single samples to the whole seas. Both the slopes and intercepts of the curves depended significantly on the logarithm of the mean body size of the group. The number of small species (ciliates and diatom algae) showed relatively higher local diversity but increased more slowly with the area than the number of larger ones. Thus, both ,- and ,-components of species diversity of the marine benthos were size-dependent. As a consequence, the actual relations between number of species and their physical size are spatially scale-dependent: there are many more species of smaller size classes in any one local community, but at a global scope the situation changes drastically. The possible reasons are discussed, including dispersal efficiency, rates of speciation and size-dependent perception of environmental heterogeneity. Body size is suggested to be the important scaling factor in manifestation of so-called "general ecological laws". [source] A zero ODP replacement for R12 in a centrifugal compressor: an experimental study using R134aINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2002C. Aprea Abstract It is well believed that the hydrofluorocarbons (HFCs) and their mixtures are the most promising candidates to substitute the conventional refrigerants, chlorofluorocarbons (CFCs) and HCFCs which contain chlorine atoms in the molecule. This substitution is necessary for the harmful action of CFCs and of HCFCs toward atmospheric ozone layer damage because the disruption of ozone has been attributed to chlorine. For this reason they must be replaced by more environment-friendly refrigerants, as the new family, designated as HFCs, that are chlorine free. Centrifugal compressors differ from positive displacement compressors in two major respects: high vapour volume flow for a given physical size and lower pressure ratio. They are particularly suited to applications where differences between evaporator and condenser temperatures are low. The preferred properties for fluids used in centrifugal compressors differ in certain important aspects from those preferred for fluids used in positive displacement units. In particular centrifugal compressors typically utilize fluids such as CFC114, CFC113, CFC12 and CFC11 for which many potential candidate replacements exist; however, for CFC12, HFC134a is the most suitable replacement. A comparison of the refrigerants HFC134a and CFC12 has been carried out and the results from the tests, using data from a refrigerating plant operating with a centrifugal compressor are reported. The chilled water cooling plant, with a refrigerating capacity of 6500 kW is made up of a centrifugal two-stage compressor, a condenser linked to a cooling tower, an economizer and a flooded evaporator. Experimental results show that a lower coefficient of performance is found when R134a is used as substitute for R12; the difference between the COP values decreases rising the compression ratio. Copyright © 2002 John Wiley & Sons, Ltd. [source] An optimum design of deep-space downlinks affected by tropospheric attenuation,INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2009Emilio Matricciani Abstract In the paper, we propose an optimum design of deep-space downlinks made with 2 hops, at Ka band and above, in which each hop should be designed for providing half of the total noise-to-signal power ratio. We have derived this result from maximizing the ratio between the tropospheric attenuation in the 2-hop downlink and that in the 1-hop downlink. The design of the 1st hop (free-space) of the 2-hop downlink can reduce the spacecraft power, for the same antennas physical size, by increasing the carrier frequency from Ka band (32,GHz) to W band (80,GHz). This choice is not available in 1-hop downlink design because of the huge Earth tropospheric attenuation expected in the W frequency band. To show a practical design, we have applied the theory to compare 1-hop downlink design at 32,GHz to 2-hop downlink design that adopts 32 or 80,GHz in the 1st hop. The calculations refer to spacecrafts located at two astronomical units (300×106,km, about planet Mars) and to NASA and ESA receiving stations located in Goldstone (California), Cebreros (Madrid, Spain), Canberra and New Norcia (Australia). At 0.1% outage probability, in an average year or in the worst month, 1-hop downlinks show performance critical or close to fail, because of the large tropospheric attenuation (except at Goldstone), while 2-hop downlinks always work. Copyright © 2009 John Wiley & Sons, Ltd. [source] Bigger is better: the influence of physical size on aesthetic preference judgmentsJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 3 2002David H. Silvera Abstract The hypothesis that the physical size of an object can influence aesthetic preferences was investigated. In a series of four experiments, participants were presented with pairs of abstract stimuli and asked to indicate which member of each pair they preferred. A preference for larger stimuli was found on the majority of trials using various types of stimuli, stimuli of various sizes, and with both adult and 3-year-old participants. This preference pattern was disrupted only when participants had both stimuli that provided a readily accessible alternative source of preference-evoking information and sufficient attentional resources to make their preference judgments. Copyright © 2002 John Wiley & Sons, Ltd. [source] A wideband planar monopole microstrip antenna with coupled parasitic linesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2006Lu Lu Abstract A wideband microstrip-fed monopole antenna with two shorted inverted-L coupled lines is presented. The proposed antenna has a large impedance bandwidth covering the range from 3.22 to 11.68 GHz. The radiating elements only occupy a small area of 9.3 × 8.2 mm2. The gain and bandwidth of the antenna are predicted using a commercial finite-element method software package. For frequencies across the operating bands, the proposed antenna displays monopolelike radiation patterns and good antenna gain, given its small physical size. The predicted results show good agreement with measured data. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1507,1509, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21718 [source] | ||||||||||