322 research outputs found
Prediction of in situ rock strength using sonic velocity
Uniaxial Compressive Strength (UCS) and sonic velocity correlations are used widely in the Australian coal mining industry to predict in situ rock strength. These models are cheap, fast and easy to produce, as well as easy to understand and have a number of practical applications in mine planning and design. The major downfall of these models is that there is a large variation in UCS values at high sonic velocities limiting their predictive ability. The aim of this research project is to improve the reliability of UCS/Sonic velocity correlations by reducing the variability in the underlying data. This is performed by identifying and eliminating sources of error affecting the data and looking at the impact of certain factors on the quality of the correlations. Results show that improved models can be obtained by filtering the datasets to remove samples with high length-to-height ratios, conglomerate or pebbly lithologies, and large sonic velocity ranges
Effects of different planting dates on improving yield of Fritillaria imperialis L. and Fritillaria persica L. bulbs damaged by small narcissus fly (Eumerus strigatus Fallen)
Fritillaria imperialis and F. persica were planted during April 2003 and May 2004 growing seasons on the basis of split block design with three replications to investigate the effects of planting dates on various plant parameters and extent of recovery by planting 25% damaged bulbs. The results showed significant effects of planting dates on plant height, number of bulbs per plant and infected bulb ratio. A comparison of the two species showed that F. persica gave more bulblets than F. imperialis. A generalcomparison of the two species also showed that damaged bulbs of F. imperialis produced lesser yield compared to F. persica. Furthermore, both species gave more number of bulblets from early and mid September plantings compared to early and mid October plantings. The most suitable date of planting was determined as September 1st and 15th
A study on wear rates of 100Cr6 steel running against sintered steel surfaces under dry and starved lubrication
This paper investigates the tribological behavior of 100Cr6 steel pin running against sintered steel bearing material used in hermetic compressors. Tests were conducted under dry and starved lubrication sliding conditions in air at room temperature. Although porous structure acts as crack initiation sites thus limiting the wear resistance of sintered iron in dry sliding conditions under high contact stresses, it is believed to be beneficial in lubricated sliding conditions as it absorbs a large amount of lubricant. Wear tests without lubrication show that these pores are completely filled by abrasive particles in the initial stages of the test and no longer maintain their oil absorption capability. Initial results show that oxidation of frictional surfaces by flash temperature in dry conditions reduces weight loss volume by decreasing the
coefficient of friction
Effects of sowing date on some agronomic characteristics and alkaloid content of Datura stramonium in semi-arid conditions
Alkaloids of diferent plant,
including many Solanaceae species,
constitute important natural sources for
variety of pharmaceutical products. The
amounts of various secondary plant
products are strongly dependent on the
growing conditions and agronomical
applications such as planting date,
fertilization, irrigation etc. The aim of this
was to study the effects of sowing date on
some agronomic characteristics and total
alkaloid content of thorn apple (Datura
stramonium), investigated in the
environmental conditions from Dicle
University, Agricultural Faculty, Field
Crops Department experimental area, during
2010 and 2011 growing years. In the
research, plant height, stem diameter,
number of branches per plant, number of
capsule per plant, capsule width, capsule
length, 1000-seed weight, fresh herb yield,
herba yield, seed yield and total alkaloid
content were examined. At the end of the
study, in the trial of thorn apple with sowing
dates, according to two years mean, seed
yield, fresh herb yield, dry herb yield and
total alkaloid yield were changed between
335 kg ha-1 and 704 kg ha-1, 5933 and 20537
kg ha-1, 1613 kg ha-1 and 4800 kg ha-1, and
0.270% and 0.391%, respectively. The
effect of sowing date was found significant
on the investigated characteristics, when
sowing delayed, agronomic characteristics
were also decreased. The highest values
related with seed yield, fresh and dry
herbage of thorn apple were obtained
sowing of 01 Apr. Moreover, thorn apple
plant showed morphogenetic variation when
compared leaf and seed alkaloid contents
Essential oil and microelement composition of Thymus citriodorus L. and Lippia citriodora H.B.K.
Lemon verbena (Lippia
citriodora H.B.K., Verbenaceae family) is
indigenous to South America and cultivated
as an aromatic plant in various parts of
world. Lemon thyme (Thymus citriodorus
L.), Lamiaceae family, is a perennial
medicinal plant native to southern Europe
and is cultivated in the Mediterranean
region. These species are cultivated mainly
for the lemon-like aroma emitted from their
leaves due to the presence of dimethyl-2,6-
octadienal, also known as lemonal or citral,
which is used in food and perfumery for its
citrus effect. The aim of this study was to
determine the mineral content and essential
oil components of L. citriodora and
T. citriodorus plants grown under semi-arid
climatic conditions in Turkey. The aerial
parts of lemon thyme and lemon verbena
plants were extracted using hydrodistillation.
The essential oil composition
was analyzed by gas chromatography-mass
spectrometry (GC-MS) and the
microelement contents of the herbs were
examined via inductively coupled plasmaoptical
emission spectrometry (ICP-OES).
The microelement contents were 0.249,
1.630, 16.41, 0.106, and 13.1-36.2 mg kg-1
for cadmium (Cd), copper (Cu), iron (Fe),
and manganese (Mn), respectively, in lemon
thyme, and 0.275, 4.584, 248.1, 15.71, and
1.803 mg kg-1 for Cd, Cu, Fe, Mn, and zinc
(Zn), respectively, in lemon verbena. Fifty
compounds were identified in lemon
verbena essential oil, including limonene
(30.33%), trans-citral (17%), cis-citral
(12.77%), caryophyllene oxide (5.71%), and
geraniol acetate (4.02%) that together
constituted 99.86% of the oil composition.
We also identified 22 compounds
constituting approximately 85.11% of
lemon thyme essential oil, including transgeraniol
(30.07%), trans-citral (15.06%),
cis-citral (11.71%), cis-geraniol (7.65%),
and 3-octanol (6.18%)
Effect of different nitrogen doses on some agricultural characteristics and alkaloid content of Hyoscyamus reticulatus L and Hyoscyamus Niger L.
Alkaloids, nitrogen
containing basic substance, have a complex
structure. They are one of the most
important groups of secondary metabolites,
which is synthesized in roots and
transported to other organs. Since alkaloids
are nitrogenous compounds, the availability
of nitrogen is expected to play an important
role in the biosynthesis and accumulation of
alkaloids in plants. Nitrogen affects yield
and quality of medicinal plants, therefore,
growers usually apply large amount of
nitrogen to obtain high yields. The objective
of the present study was to determine yield,
yield components and alkaloid content of
two henbane species (Hyoscyamus
reticulatus L. and Hyoscyamus niger L.),
collected from wild flora of South-eastern
Anatolia, grown under four nitrogen
applications (0, 50, 100 and 200 kg ha-1), in
2010-2011 growing seasons. In the field
trial, plant height, stem diameter, number of
branches per plant, number of capsule per
plant, capsule width, capsule length, number
of seed per capsule, 1000 seed weight, seed
yield per plant and total alkaloid content
were investigated. The results of study
showed that nitrogen doses were found
important for investigated characters but not
important for Hyoscyamus species. Seed
yield per plant varied from 8.4 to 11.6 g per
plant, their alkaloid contents were found
between 0.14% and 0.21%
Modelling of the Occurrence of Hydrogen Sulphide in Coal Seams
Hydrogen Sulphide (H2S) has been encountered within a number of Bowen Basin collieries, Central Queensland, Australia. High concentration occurrence during mining of a longwall panel raises a number of potential problems, which demand greater understanding to allow efficient mining while maintaining safe and healthy environmental conditions. Longwall panels at Mine A and Mine B have recently mined through H2S zones. The high H2S zone mined through at Mine A was wide and covering the whole length of the face comparing to the narrow H2S zone which was cutting the panel at 45° at Mine B. Longwall panels had been sampled for H2S in pre-mining phases with vertical and inseam exploration boreholes and rib sampling of gateroad development headings. During mining face coal samples were collected in an intensive program and tested in a drum tumbler to determine an indicated seam concentration level through contouring that could be used to calculate the concentrations of H2S liberated to the atmosphere. Data was analysed to determine a geostatistical method, which would best represent the indicated seam concentration level from the given data and the block dimension of the data set. This study discusses the different sampling methods used, selection of the most suitable geostatistical method and the impact of grid size on results of data analysis. Some general observations are made correlating indicated seam H2S concentrations from production face sampling with both predictions made from exploration and liberation rates during mining of the longwall panel
Improving the performance of the hardy cross algorithm for large ventilation models
The Hardy Cross algorithm offers a reliable method of solving network systems of fluid flow and has become widely used for solving water and ventilation flow networks. A limitation is that computational iterations and time to solve a network rises rapidly with the size of the model and modern detailed ventilation networks have typically grown to thousands of airways. Non-linear matrix solving methods can offer improved performance, however these are more complex and may be unstable if initial estimates are poor. This paper presents improvements that can be applied to the traditional Hardy Cross algorithm to greatly reduce iterations and solving time for large ventilation models
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