Small Pans Research Articles

A study of the conversion of different evaporation pans in South China based on the extreme learning machine model

ABSTRACT Evaporation is important basic information for irrigation decision making in water resources management. Developing countries usually use a small pan to observe surface evaporation, but the relationship between evaporation in different small pans is not sufficiently clear. In this paper, we use an extreme learning machine (ELM) model to predict and convert E20 (diameter 0.20 m) and E601 (diameter 0.62 m) pan data for 38 meteorological stations in southern China. Firstly, we obtained the best combination of meteorological parameters for forecasting E20 and E601, respectively, and we also found that the accuracy of the model can be significantly improved by adding pan data. Secondly, we found that during the conversion between E20 and E601, the model performance when using E601 data to predict the E20 evaporation is better than that when using E20 data to predict the E601 evaporation. Finally, the geographical factors were analysed, and the model performance was found to be relatively poor in the coastal area and the North–South junction.

Modelling of unsteady pool fires – fuel depth and pan wall effects

This paper presents physics-inspired mathematical model to predict the time varying burn rate of unsteady pool fires. The model benefits from the observations on the thermal behaviour and select data from systematically and carefully designed experiments on small and large pool fires of n-heptane and small pool fires of diesel, kerosene and ethanol fuels. All modelling features are based on dimensionless quantities. Amongst the three controlling heat transfer mechanisms, convection is dealt with simply. However, conduction and radiant heat transfer models have needed new considerations. A combination of steady and unsteady conduction along the pan wall affected by the thermal properties of the wall material and liquid phase conduction are modelled and validated against specific experiments. Radiant heat transfer modelling differs from the conventional approach to account for fuel depth-dependent enhancement in burn flux in small pans to values comparable to large pool fires. The radiation view factor invokes mass flux based Reynolds number to account for fuel depth-related effects. Several constants are modelled in terms of dimensionless parameters constructed from a large number of physical variables of the pan and the fuel and used in the model such that they allow the best fits between the simulation and a part of the experimental data. All the sub-models combined into a surface heat flux balance provide the temporal variation of the mass depletion as also the relative magnitudes of the fluxes in a MATLAB code. Comparisons of the predictions on the dependence of the burn behaviour on fuel depth, free board, pan diameter and wall material with the experimental data of the present authors and from literature on n-heptane are set out. Comparisons between the predictions and experimental data on diesel, kerosene and ethanol are also set out to show the ability of the model to track the mass loss history based on fundamental properties of the fuel and the pan. The outstanding-to-good quality of predictions in most cases is attributed to the necessary physics taken into account in the model.

Use of Weather and Climate Information in Decisions on Conservation of Water Resources in Kilombero River Catchment, Tanzania

The authors thankfully acknowledge the financial support from Uncertainty Reduction in Models for Understanding Development Applications (UMFULA) Project under the Future Climate for Africa (FCFA). Special thanks go to Declan Conway (London School of Economics and Political Science) who contributed invaluable inputs to the publication. Abstract This study assessed the use of climate information in decisions on the conservation of water resources and determined influencing factors in Kilombero River Catchment in Tanzania. A cross-sectional research design was employed. Purposive sampling was used to select Kilombero, Ulanga and Malinyi districts and Lumemo, Nakafulu and Biro villages while simple random sampling was used to select respondents. A total of 120 household respondents were interviewed in the three villages. In addition, 7 Key Informants’ Interviews (KIIs) involving officers from Kilombero Game Controlled Area (KGCA) and Rufiji Basin Water Board (RBWB) and 3 Focus Group Discussions (FGDs) with the villagers were conducted. Quantitative data were analyzed using Statistical Package for Social Science (SPSS) and STATA computer programs while qualitative information was analyzed using content analysis. Results show nearly half of respondents of weather and climate information in decisions to conserve water resources. Although ten decisions were identified in the area, weather and climate information was highly used in deciding conservation measures (X 2 =5.992, p<0.05), construction of small pans or bore holes for water storage (X 2 =6.580, <0.05) and reducing the number of livestock (X 2 =5.889, p<0.05). Four variables which had significant and positive correlation with conservation of water resources were identified. Foremost among them is extension visits (s=0.079; p<0.01) which implied access and frequency of extension visits influence use of weather and climate information in making decisions. It is concluded that communities in the area use weather and climate information in decisions which conserve water resources. Policy makers are advised to emphasize factors which had positive significant correlation with conservation of water resources. Keywords: Climate Information Use, Water Conservation Decisions. DOI: 10.7176/JEES/10-4-06 Publication date: April 30 th 2020

PHERECRATES FR. 60: SPINY FISH-HEADS, BUT NO SCRAPS

The scholia to Wasps gloss τραχήλια variously as τὰ ἄκρα καὶ τὰ εὐτελῆ κρέα (‘cheap trimmings of meat’), τὰ ἀποβαλλόμενα τῶν ὄψων (‘discarded scraps of prepared dishes’), ὀστράκιόν τι βραχὺ τελέως (‘a tiny bit of bone’), and εὐτελὲς προσόψημα ἐν λοπαδίσκοις σκευαζόμενον (‘a cheap side-dish prepared in small pans’). These might all be guesses, but the absence of the definite article in the original text shows that Bdelycleon's reference is to something more generic than ‘the backbones’ in the next verse. The ancient commentators were thus probably right not to interpret the word ‘bits of neck’, vel sim., as if this were a diminutive of τράχηλος (‘neck’ or ‘head and neck’). Instead, these must be ‘tail-ends’ of food, scraps and leftovers of a sort that might be fed to a dog; compare Hippocrates, Epidemiae 7.62 (v.428.7 Littré), where βόεια τραχήλια (‘beef tit-bits’, vel sim.) are mentioned along with ham as part of the diet of a man recovering from illness.

A hotspot of large branchiopod diversity in south-eastern Zimbabwe

Large branchiopods are considered threatened across much of their global range. However, because several regions, including Zimbabwe in general and its south-eastern lowveld in particular, remain largely unstudied, interpretations of species distribution patterns are often based on limited data. A detailed study of large branchiopods was carried out, with repeated sampling of 36 seasonal pans, in 2004-2008 in the Save Valley Conservancy, south-eastern lowveld. Sixteen large branchiopod species were collected, comprising eight Anostraca, one Notostraca, two Laevicaudata, four Spinicaudata and one cyclestherid species, representing 33% of all species known in southern Africa. Most species were new records for Zimbabwe. The enigmatic morphotype, Streptocephalus cf. bidentatus, was encountered for the first time in Zimbabwe, presenting an opportunity to resolve its taxonomic status. Streptocephalus wirminghausi, a species endemic to Zimbabwe, was also recorded. Large endorheic pans had higher species richness (an average of eight species) than small endorheic pans (average of six species), whilst floodplain pans housed fewest species (average of four species), probably due to predation by fish after floods. Since regional diversity and coexistence levels in the Save Conservancy were high, compared to other regions, this area should be considered a hotspot of large branchiopod diversity.

Erodibility and runoff-infiltration characteristics of volcanic ash soils along an altitudinal climosequence in the Ecuadorian Andes

Soil erosion is a widespread phenomenon in Andean South America, where many regions are covered with soils derived from volcanic parent materials. Climate-induced differences in the genesis of these soils have been demonstrated along toposequences on volcanic slopes. This research was conducted to study the impact of such differential pedogenesis on erodibility and runoff-infiltration characteristics along an altitudinal Entisols–Inceptisols–Andisols sequence in the Andes of northern Ecuador. Surface soils were packed into small pans and placed on a 9% slope, and a simulated rainstorm with varying intensities was applied for a duration of 30 min. The runoff-erosion behaviour of the studied volcanic ash soils is strongly affected by their pedological development. Accumulation of organic matter and precipitation of active amorphous materials at high elevations have led to the formation of well-developed Andisols with very stable aggregate structure. These soils remain wettable when air-dried, show very high infiltration capacity and, consequently, low potential for runoff generation and soil erosion. Low organic matter contents and absence of active amorphous materials at low elevations have led to the formation of weakly aggregated Entisols and Inceptisols. These soils are susceptible to surface crusting, which lowers their infiltration capacity and increases their erodibility. However, in comparison with other soils of different origin and composition, the interrill erodibilities determined for these more erodible low-elevation soils are classified as low. The findings of this study suggest that upland soil erosion is not a major threat to sustainability in the studied volcanic landscape, which is generally confirmed by field observations.

Processes of silicate karstification associated with pan formation in the Darwin–Koolpinya area of northern Australia

AbstractLyons Lagoon, one of many small pans near Darwin, Northern Australia, occurs in lateritized terrain. Formation by structurally facilitated silicate karstification of the parent Cretaceous sandy sediments was earlier proposed. This paper presents the results of thin section microscopy and scanning electron microscopy with energy‐dispersive X‐ray study of pan sediments with a view to assessing the extent to which they reflect the geomorphological/hydrogeological history. Severe corrosion was found to overprint the impact features of the primary sands, attributed to aggressive leaching and consistent with formation of the depression by karstification when the water table was low. Formation of a smectitic matrix is considered to have followed when the water table was high. Upon subsequent lowering of the water level leaching was resumed, altering smectite to kaolinite and resulting in incongruent dissolution of kaolinite to leave a siliceous residuum. At least two cycles of high followed by low water levels are recognized. Such periodic changes of levels are considered essential to pan formation within freely draining lateritic terrain. The processes of pan formation and alteration of pan sediments (essentially residual deposits) is ongoing, biocorrosion being implicated as an important mechanism. Incongruent kaolinite dissolution, to leave a silica residuum, a hitherto apparently unrecognized process, raises the possibility that silcrete may form as a relative accumulation which is synchronous with lateritic leaching in more elevated topographic positions. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Bedload and water-column transport and colonization processes by post-settlement benthic macrofauna: Does infaunal density matter?

In this study, we document dispersal and colonization by post-settlement benthic macrofauna on a large (250×500 m) area of intertidal sandflat at Wiroa Island in the Manukau Harbour, New Zealand, over a 2-week period in February 1994. We examine the effects of variation in the natural density of large (>15 mm) Macomona liliana Iredale (a tellinid bivalve) on these processes. Post-settlement transport was measured using cylindrical bedload and water-column traps positioned at 22 experimental sites within the study site. Macrofaunal colonization was documented using small pans of defaunated sediment deployed at each of the experimental sites. Greatest macrofaunal colonization of pans occurred in areas of greatest sediment reworking and deposition, suggesting transport and deposition of post-settlement stages may be passive processes. For some species [e.g. Austrovenus stutchburyi (Wood)] there was a significant positive relationship between their abundance and the weight of sediment in bedload traps, as well as wind conditions over the study period. This is consistent with passive transport processes, but does not exclude the possibility of active dispersal processes also being important. Differences in the hydrodynamic conditions (e.g. increased wind generated wave activity) over the 2-week study may have contributed to changes in abundance on the 2 sampling dates. For other species (e.g. Macomona liliana) the absence of significant positive relationships between abundance in either bedload or water-column traps and the weight of sediment retained in traps, as well as between ambient densities and the net flux of individuals across sites, is consistent with active dispersal and colonization. There was a negative relationship between background density of large Macomona liliana and numbers of smaller conspecifics (≤4 mm) and other bivalves [ Austrovenus stutchburyi, Cyclomactra ovata (Gray) and Nucula hartvigiana Pfeiffer] colonizing pans of defaunated sediment. The results suggest that 10 to 100s m scale variation in the natural densities of an abundant siphonal surface deposit feeder may have a significant influence on dispersal and colonization and, thus, the spatial patterns of macrofauna on the tidal flat.

Seasonal changes in the invertebrate community of small shallow ephemeral pans at Bain's Vlei, South Africa

Changes in invertebrate population numbers and composition were monitored in six small shallow ephemeral pans during four consecutive inundations of spring, summer and autumn 1988/1989. The community was generally characterized by crustaceans and was invaded by insect larvae in summer. Community changes and succession were prominent in spring but less so in summer and autumn. Large pans supported more species than small pans. During longer inundation there was less difference between the initial and the final population composition than during shorter inundation, although the total population density did not increase significantly. This indicated that population composition stabilized as inundation lengthened. Population changes of six representative taxa were not correlated to changes in the physical and chemical characteristics of the water.

Variations in the morphological characteristics ofTriops granarius (Lucas) (Crustacea:Notostraca) in a pan system at Bain's Vlei, South Africa

The morphological characteristics of a population ofTriops granarius in a system of small pans were examined during inundations of one season. Considerable variation was found in a number of characteristics. Differences in gender other than those of the reproductive organs were also significant, but diagnostic characteristics remained stable.

Interrill erodibility of highly weathered soils

Abstract In this study topsoil samples of fifteen Georgia Ultisols and Alfisols were used to assess the relative importance of total and water‐disperslble particle size distribution, and aggregation by wet sieving on interrill erodibility. A measure of aggregate stability to raindrop impact and amounts of soil splash were also determined on the soils. Water‐dispersibility was hypothesized to more accurately reflect availability of particles for transport and crusting under rainfall conditions than total (chemically dispersed) particle size. Correlation analysis showed that total silt and clay were not related to soil loss measured on small pans (interrill processes), nor were meaures of soil splash or stability under rainfall. Dispersible clay content and percentage of aggregates > 1 mm diameter were correlated with soil loss. Regression of dispersible clay vs. soil loss gave significant linear and exponential predictive relationships. The effect of clay dispersion on both detachment and transport of sediments appears to explain these results.

Versatile shuttle cloning vectors for the unicellular cyanobacteriumAnacystis nidulansR2

3 new shuttle cloning vectors for gene transfer into Escherichia coli and Anacystis nidulans have been constructed by utilizing the cyanobacterial origin of replication of the small plasmid pANS from A. nidulans. 2 of these new vectors, pXB7 (pDPL13 derivative) and pECAN8 (pUC8 derivative), convey ampicillin resistance, and transform A. nidulans with relatively high frequencies. Vector pXB7 has 10 unique cloning sites; pECAN8 contains 4 cloning sites within the lacZ gene permitting rapid detection of DNA inserts in the presence of Xgal. The third vector, pKBX, has a lower transformation frequency but adds kanamycin resistance as a selectable gene for shuttle vectors of cyanobacteria.

Statistical Laws and Dune Ridges in Southern Africa

In a recent note, Mabbutt and Sullivan (1968) investigated the nature and impor? tance of Y-junctions in dune ridge systems in Central Australia. From the descriptions in their paper, and also those of Mabbutt (1968) and Madigan (1936), it appears clear that the sand-ridges in question are very similar to those in the southern Kalahari. The dunes around the Molopo River before it reaches the large pan of Abiquas Puts (27?20/S, 20?io/E) correspond to Mabbutt's 'parallel ridges* and 'ridges with intersecting trends*. They are mainly between 10 and 25 m high, with a spacing of around 300 m. Their surfaces are lightly vegetated, with the vegetation occurring mainly along the crests, though the sand on the upper parts of the dunes is still capable of movement. Rainfall totals are around 17 cm per annum. The dunes were discussed in an early paper by Lewis (1936), whilst the Kalahari dunes in general have been mapped and described by Grove (1969). The sand has a mean size of 2-2 0 (approxi? mately 0*21 mm). Between the dunes there are many small pans or defiation basins, some of which may now be smaller than in the past. Some old strand lines seem to be evident, for example, around Abiquas Puts itself, whilst recently the Molopo channel has become crossed and constricted by small dunes. The Y-junctions in the Molopo area are of great interest as they appear to be random in distribution, and to be associa? ted with a network of dunes that obeys Horton*s Law of Stream Numbers (Horton, 1945). Using air photographs made available by the South African trigonometrical survey in Pretoria, I mapped the dune systems, and was able to identify 'basins* consisting of discrete dune networks which form, topologically, simply connected trees. Hence it is of interest to explore the formal analogy between these dune systems and river systems. After delineating the 'basins* the dune segments were ordered after the method of Strahler (1952), and dune order was plotted against numbers of dunes of each order on semi-logarithmic paper. A straightline inverse relationship was estab? lished. These dunes therefore obey Horton*s Law of Stream Numbers which states 'the number of streams of different orders in a given drainage basin tend closely to approximate an inverse geometric series in which the first term is unity and the ratio is the bifurcation ratio* (Horton, 1945, p. 291). Subsequent to Horton*s work, the law has been found to apply to a large number of diverse phenomena: alpine glaciers, bovine livers, some trees, and some road networks (Woldenburg, 1968). Because of the statistical nature and 'remarkable generality* of Horton*s Law of Stream Numbers, Shreve (1966) suggested that the law arises from the statistics of a large number of randomly merging stream channels. To test the applicability of this suggestion for dunes, I tested the distribution of dune junetions for randomness by plotting the nodes, and then counting the number of nodes in square quadrats (Kershaw, 1964). In no case did the number of nodes in any one quadrat exceed six. The mean density of nodes per quadrat was obtained (m), and then, following Kershaw (p. 99), from the Poisson distribution, e_m, me_m, m2e~m/2!, m3e~m/3!,.,.,.,

Rate of combustion from free surfaces of liquid hydrocarbons

The burning velocity of n-hexane and cyclohexane as related to the area of the burning fuel surface was studied using 10 open pans ranging from 0·22 to 11·94 in. in diameter. On the four larger pans fuel temperatures were also measured during the burning period at two depths below the surface. For small pans less than 5 in. in diameter burning velocity decreased with increasing pan size. For pans greater than 5 in. in diameter burning velocity increased with increasing pan size. Thus, there appear to be two burning regimes in the range of pan diameters tested, a laminar flow regime on small pans, and a transition flow regime on larger pans. This observation is in agreement with the experimental results reported by others for equivalent pan sizes burning less volatile hydrocarbon fuels.

The Multiple-Cone Sample Splitter

ABSTRACT A multiple-cone sample splitter, consisting of a series of powder funnels and inverted brass cones mounted alternately in a vertical column over a tray containing small sector-shaped pans,shortens the time necessary to reduce samples to grain-counting size by about 75 percent. A sample design has been set up by which three methods of sample splitting for grain counting--the microsplit, the cone splitter, and hand-quartering--may be compared. The methods of sample splitting are used for one classification in the design and the sample weights of 5, 10, and 20 grams of known grain composition for the other classification. Only one subset of data--that of the 5-gram sample split by the cone splitter--showed a value of 2 for precision that was equal to or less than that expected from chance alone. Similar calculations for estimates of accuracy show that the 5-gram sample by the cone splitter and the 10-gram sample by hand-quartering do not exceed the 2 values due to chance alone. If the subtotals of the 33 experimental design are used to calculate 2, it is seen that: (1) the splitting of the 5-gram sample by all methods is both more accurate and more precise than the splitting of the other two sample weights; and using the three weights for each method (2) the microsplit is the least accurate and the least precise of the three methods, (3) the hand-quartering is slightly more precise than the cone splitter, and (4) the cone splitter is slightly more accurate than hand quartering.

On the Mechanisms of Snow Melting-Some Studies on the Snow Melting by the Heat Transferred from the Air and Latent Heat of the Vapor

It is radiant heat (the solar radiation and thermal radiation), the heat transferred from the air and the latent heat of vapor that participate mainly in snow melting.Now, there is the analogy between heat transfer and condensation to pans. (Reynolds' analogy.) On this theory, I find the following formulas, for the small pans.(1) When windless, m = 2.1 l-1/4 θ'5/4× 10-3 gr/cm2. hr.where (m) is the rate of snow melting by the heat transferred, (l) is the length of the pan in cm and (θ') is temperature of the air current. Andm= 4.9 l-1/4|co-c'|θ1/4 ×104 gr/cm2. hr.where (m') is the rate of snow melting by the latent heat of the vapor, (co) anc (c') are respectively vapor concentration on the snow surface and in the air current in gr/cm2. (2) Under the laminar boundary condition, m= 4.0 l-1/2U1/2θ' × 10-3 gr/cm2. hr.where (U) is the wind valocity in cm/sec. And m'=9.0l1/2U1/2|co-c'|× 10-3=7.2 l-1/2U1/2|p'-6.1|× 10-3gr/cm2where (p') is vapor pressure in the air current in mb.(3) Under the turbulent boundary condition, m=3.4 l-1/5U4/5 θ'10-4 gr/cm2. hr.andm'=6.4l-1/5U4/5|co-c'|× 102=5.1l-1/5U4/5|p'-6.1|× 10-4gr/cm2.hrBut the above-mentioned are the case of smooth surface. In the cases of rough surface, perhaps, the rate of snow melting may be much more rapid.