Abstract: Land use change, if not based on proper scientific
investigation affects other physical, chemical, and biological
properties of soil and leading to increased destruction and erosion. It
was imperative to study the effects of changing rangelands to
farmlands on some Soil quality indexes. Undisturbed soil samples
were collected from the depths of 0-10 and 10-30 centimeter in
pasture with good vegetation cover(GP), pasture with medium
vegetation cover(MP), abandoned dry land farming(ADF) and
degraded dry land farming(DDF) land uses in Ghareh Aghaj
watershed of Isfahan province. The results revealed that organic
matter(OM), cation exchange capacity(CEC) and available
potassium(AK) decreasing in the depth of 0-10 centimeter were 66.6,
38.8 and 70 percent and in the depth of 10-30 centimeter were 58,
61.4 and 83.5 percent respectively in DDF comparison with GP.
Concerning to the results, it seems that land use change can decrease
soil quality and increase soil degradation and lead in undesirable
consequences.
Abstract: The aim of the study was to investigate phytochemical
properties, antimicrobial activity and cytotoxicity of Aloe vera. The
phytochemical screening of the extracts of leaves of A. vera revealed
the presence of bioactive compounds such as alkaloids, tannins,
flavonoids phenolic compounds, and etc. with absence of cyanogenic
glycosides. Three different solvents such as methanol, ethanol and
Di-Methyl sulfoxide were used to screen the antimicrobial activity of
A. vera leaves against four human clinical pathogens by agar well
diffusion method. The maximum antibacterial activities were
observed in methanol extract followed by ethanol and Di-Methyl
sulfoxide. It was also found that remarkable antibacterial activities
with methanolic and ethanolic extracts of A. vera compared with the
standard antibiotic, tetracycline that was not active against E. coli
and S. boydii and supported the view that A. vera is a potent
antimicrobial agent compared with the conventional antibiotic.
Moreover, the brine shrimps (Artemia salina) toxicity test exhibited
LC50 value was 569.52 ppm. The resulting data indicated that the A.
vera plant have less toxic effects on brine shrimp. Hence, it is
signified that Aloe vera plant extract is safe to be used as an
antimicrobial agent.
Abstract: The essence of the 21st century is knowledge economy. Knowledge has become the key resource of economic growth and social development. Construction industry is no exception. Because of the characteristic of complexity, project manager can't depend only on information management. The only way to improve the level of construction project management is to set up a kind of effective knowledge accumulation mechanism. This paper first introduced the IFC standard and the concept of ontology. Then put forward the construction method of the architectural engineering domain ontology based on IFC. And finally build up the concepts, properties and the relationship between the concepts of the ontology. The deficiency of this paper is also pointed out.
Abstract: We present an operator for a propositional linear temporal logic over infinite schedules of iterated transactions, which, when applied to a formula, asserts that any schedule satisfying the formula is serializable. The resulting logic is suitable for specifying and verifying consistency properties of concurrent transaction management systems, that can be defined in terms of serializability, as well as other general safety and liveness properties. A strict form of serializability is used requiring that, whenever the read and write steps of a transaction occurrence precede the read and write steps of another transaction occurrence in a schedule, the first transaction must precede the second transaction in an equivalent serial schedule. This work improves on previous work in providing a propositional temporal logic with a serializability operator that is of the same PSPACE complete computational complexity as standard propositional linear temporal logic without a serializability operator.
Abstract: Let p be a prime number, Fp be a finite field and t ∈ F*p= Fp- {0}. In this paper we obtain some properties of ellipticcurves Ep,t: y2= y2= x3- t2x over Fp. In the first sectionwe give some notations and preliminaries from elliptic curves. In the second section we consider the rational points (x, y) on Ep,t. Wegive a formula for the number of rational points on Ep,t over Fnp for an integer n ≥ 1. We also give some formulas for the sum of x?andy?coordinates of the points (x, y) on Ep,t. In the third section weconsider the rank of Et: y2= x3- t2x and its 2-isogenous curve Et over Q. We proved that the rank of Etand Etis 2 over Q. In the last section we obtain some formulas for the sums Σt∈F?panp,t for an integer n ≥ 1, where ap,t denote the trace of Frobenius.
Abstract: Polylactic acid-g-polyvinyl acetate (PLLA-g-PVAc)
was used as a compatibilizer for 50/50 starch/PLLA blend. PLLA-g-
PVAc with different mol% of PVAc contents were prepared by
grafting PVAc onto PLLA backbone via free radical polymerization
in solution process. Various conditions such as type and the amount
of initiator, monomer concentration, polymerization time and
temperature were studied. Results showed that the highest mol% of
PVAc grafting (16 mol%) was achieved by conducting graft
copolymerization in toluene at 110°C for 10 h using DCP as an
initiator. Chemical structure of the PVAc grafted PLLA was
confirmed by 1H NMR. Blending of modified starch and PLLA in the
presence compatibilizer with different amounts and mol% PVAc was
acquired using internal mixer at 160°C for 15 min. Effects of PVAc
content and the amount of compatibilizer on mechanical properties of
polymer blend were studied. Results revealed that tensile strength and
tensile modulus of polymer blend with higher PVAc grafting content
compatibilizer showed better properties than that of lower PVAc
grafting content compatibilizer. The amount of compatibilizer was
found optimized in the range of 0.5-1.0 Wt% depending on the mol%
PVAc.
Abstract: The major objective of this study is to understand the
potential of a newly fabricated equipment to study the thermal
properties of nonwoven textile fabrics treated with aerogel at subzero
temperatures. Thermal conductivity was calculated by using the
empirical relation Fourier’s law, The relationship between the
thermal conductivity and thermal resistance of the samples were
studied at various environmental temperatures (which was set in the
clima temperature system between +25oC to -25oC). The newly
fabricated equipment was found to be a suitable for measuring at
subzero temperatures. This field of measurements is being developed
and will be the subject of further research which will be more suitable
for measurement of the various thermal characteristics.
Abstract: The process for predicting the ballistic properties of a liquid rocket engine is based on the quantitative estimation of idealized performance deviations. In this aim, an equilibrium chemistry procedure is firstly developed and implemented in a Fortran routine. The thermodynamic formulation allows for the calculation of the theoretical performances of a rocket thrust chamber. In a second step, a computational fluid dynamic analysis of the turbulent reactive flow within the chamber is performed using a finite volume approach. The obtained values for the “quasi-real" performances account for both turbulent mixing and chemistryturbulence coupling. In the present work, emphasis is made on the combustion efficiency performance for which deviation is mainly due to radial gradients of static temperature and mixture ratio. Numerical values of the characteristic velocity are successfully compared with results from an industry-used code. The results are also confronted with the experimental data of a laboratory-scale rocket engine.
Abstract: Martensitic stainless steels have been extensively used for their good corrosion resistance and better mechanical properties. Heat treatment was suggested as one of the most excellent ways to this regard; hence, it affects the microstructure, mechanical and corrosion properties of the steel. In the current research work the microstructural changes and corrosion behavior in an AISI 420A stainless steel exposed to temperatures in the 980-1035oC range were investigated. The heat treatment is carried out in vacuum furnace within the said temperature range. The quenching of the samples was carried out in oil, brine and water media. The formation and stability of passive film was studied by Open Circuit Potential, Potentiodynamic polarization and Electrochemical Scratch Tests. The Electrochemical Impedance Spectroscopy results simulated with Equivalent Electrical Circuit suggested bilayer structure of outer porous and inner barrier oxide films. The quantitative data showed thick inner barrier oxide film retarded electrochemical reactions. Micrographs of the quenched samples showed sigma and chromium carbide phases which prove the corrosion resistance of steel alloy.
Abstract: The nanofiber sheet of Multiwall Cabon Nanotube
(MWCNTs)/Polyacylonitile (PAN) composites was fabricated from
electrospun nanofiber. Firstly the surface of MWCNTs was
chemically modified, comparing two different techniques consisting
of admicellar polymerization and functionalization to improve the
dispersion and prevent the aggregation in the PAN matrix. The
modified MWCNTs were characterized by the dispersion in
dimethylformamide (DMF) solvent, Laser particle size, and FTRaman.
Lastly, DSC, SEM and mechanical properties of the
nanofiber sheet were examined. The results show that the mechanical
properties of the nanofiber sheet prepared from admicellar
polymerization-modified MWCNTs were higher than those of the
others.
Abstract: The mechanical properties including flexural and
tensile of neat vinyl ester and polymer based on layered silicate
nanocomposite materials are discussed. The addition of layered
silicate into the polymer matrix increased the tensile and flexural
modulus up to 1 wt.% clay loading. The incorporation of more clay
resulted in decreasing the mechanical properties which was traced to
the existence of aggregation layers. Likewise, up to 1 wt.% clay
loading, the thermal behaviour showed significant improvements and
at higher clay loading the thermal pattern was reduced. The
aggregation layers imparted a negative impact on the overall
mechanical and thermal properties. Wide Angle X-ray Diffraction,
Scanning Electron Microscopy and Transmission Electron
Microscopy were utilised in order to characterise the interlamellar
structure of nanocomposites.
Abstract: Coated tool inserts can be considered as the backbone
of machining processes due to their wear and heat resistance.
However, defects of coating can degrade the integrity of these inserts
and the number of these defects should be minimized or eliminated if
possible. Recently, the advancement of coating processes and
analytical tools open a new era for optimizing the coating tools.
First, an overview is given regarding coating technology for cutting
tool inserts. Testing techniques for coating layers properties, as well
as the various coating defects and their assessment are also surveyed.
Second, it is introduced an experimental approach to examine the
possible coating defects and flaws of worn multicoated carbide
inserts using two important techniques namely scanning electron
microscopy and atomic force microscopy. Finally, it is
recommended a simple procedure for investigating manufacturing
defects and flaws of worn inserts.
Abstract: In composting process, N high-organic wastes loss the
great part of its nitrogen as ammonia; therefore, using compost
amendments can promote the quality of compost due to the decrease
in ammonia volatilization. With regard to the effect of pH on
composting, microorganisms- activity and ammonia volatilization,
sulfuric acid and alkaline wastewater of paper mill (as liming agent
with Ca and Mg ions) were used as compost amendments. Study
results indicated that these amendments are suitable for reclamation
of compost quality properties. These held nitrogen in compost caused
to reduce C/N ratio. Both amendments had a significant effect on
total nitrogen, but it should be used sulfuric acid in fewer amounts
(20 ml/kg fresh organic wastes); and the more amounts of acid is not
proposed.
Abstract: In this paper, creep constitutive equations of base
(Parent) and weld materials of the weldment for cold-drawn 304L
stainless steel have been obtained experimentally. For this purpose,
test samples have been generated from cold drawn bars and weld
material according to the ASTM standard. The creep behavior and
properties have been examined for these materials by conducting uniaxial
creep tests. Constant temperatures and constant load uni-axial
creep tests have been carried out at two high temperatures, 680 and
720 oC, subjected to constant loads, which produce initial stresses
ranging from 240 to 360 MPa. The experimental data have been used
to obtain the creep constitutive parameters using numerical
optimization techniques.
Abstract: The epoxidation of soybean oil at temperature of 600C
was provided the best result in terms of attaching the –OH
functionality. Temperatures below and above 600C it is likely the
attaching reaction did not proceed sufficiently fast. The considerable
yield below 40%, implies the oil is not completely converted, it is not
possible by conventional methods, because the epoxide decomposes
at the temperature required. The objective of this work was the
development of catalyst toward the conversion of epoxide and polyol
with reaction temperature at 50,60, and 700C. The effect of different
type of catalyst were studied, the effect of alcohols with different
molecular configuration was determined which leads to selective
addition of alcohols to the epoxide oils.
Abstract: Nowadays, engineering ceramics have significant
applications in different industries such as; automotive, aerospace,
electrical, electronics and even martial industries due to their
attractive physical and mechanical properties like very high hardness
and strength at elevated temperatures, chemical stability, low friction
and high wear resistance. However, these interesting properties plus
low heat conductivity make their machining processes too hard,
costly and time consuming. Many attempts have been made in order
to make the grinding process of engineering ceramics easier and
many scientists have tried to find proper techniques to economize
ceramics' machining processes. This paper proposes a new diamond
plunge grinding technique using ultrasonic vibration for grinding
Alumina ceramic (Al2O3). For this purpose, a set of laboratory
equipments have been designed and simulated using Finite Element
Method (FEM) and constructed in order to be used in various
measurements. The results obtained have been compared with the
conventional plunge grinding process without ultrasonic vibration
and indicated that the surface roughness and fracture strength
improved and the grinding forces decreased.
Abstract: In this paper, we propose a Perceptually Optimized Foveation based Embedded ZeroTree Image Coder (POEFIC) that introduces a perceptual weighting to wavelet coefficients prior to control SPIHT encoding algorithm in order to reach a targeted bit rate with a perceptual quality improvement with respect to a given bit rate a fixation point which determines the region of interest ROI. The paper also, introduces a new objective quality metric based on a Psychovisual model that integrates the properties of the HVS that plays an important role in our POEFIC quality assessment. Our POEFIC coder is based on a vision model that incorporates various masking effects of human visual system HVS perception. Thus, our coder weights the wavelet coefficients based on that model and attempts to increase the perceptual quality for a given bit rate and observation distance. The perceptual weights for all wavelet subbands are computed based on 1) foveation masking to remove or reduce considerable high frequencies from peripheral regions 2) luminance and Contrast masking, 3) the contrast sensitivity function CSF to achieve the perceptual decomposition weighting. The new perceptually optimized codec has the same complexity as the original SPIHT techniques. However, the experiments results show that our coder demonstrates very good performance in terms of quality measurement.
Abstract: A satured liquid is warmed until boiling in a parallelepipedic boiler. The heat is supplied in a liquid through the horizontal bottom of the boiler, the other walls being adiabatic. During the process of boiling, the liquid evaporates through its free surface by deforming it. This surface which subdivides the boiler into two regions occupied on both sides by the boiled liquid (broth) and its vapor which surmounts it. The broth occupying the region and its vapor the superior region. A two- fluids model is used to describe the dynamics of the broth, its vapor and their interface. In this model, the broth is treated as a monophasic fluid (homogeneous model) and form with its vapor adiphasic pseudo fluid (two-fluid model). Furthermore, the interface is treated as a zone of mixture characterized by superficial void fraction noted α* . The aim of this article is to describe the dynamics of the interface between the boiled fluid and its vapor within a boiler. The resolution of the problem allowed us to show the evolution of the broth and the level of the liquid.
Abstract: Mycophenolic acid “MPA" is a secondary metabolite
of Penicillium bervicompactum with antibiotic and
immunosuppressive properties. In this study, fermentation process
was established for production of mycophenolic acid by Penicillium
bervicompactum MUCL 19011 in shake flask. The maximum MPA
production, product yield and productivity were 1.379 g/L, 18.6 mg/g
glucose and 4.9 mg/L.h respectively. Glucose consumption, biomass
and MPA production profiles were investigated during fermentation
time. It was found that MPA production starts approximately after
180 hours and reaches to a maximum at 280 h. In the next step, the
effects of methionine and acetate concentrations on MPA production
were evaluated. Maximum MPA production, product yield and
productivity (1.763 g/L, 23.8 mg/g glucose and 6.30 mg/L. h
respectively) were obtained with using 2.5 g/L methionine in culture
medium. Further addition of methionine had not more positive effect
on MPA production. Finally, results showed that the addition of
acetate to the culture medium had not any observable effect on MPA
production
Abstract: The main aim of this research is to study the possible
use of recycled fine aggregate made from waste rubble wall to
substitute partially for the natural sand used in the production of
cement and sand bricks. The bricks specimens were prepared by
using 100% natural sand; they were then replaced by recycled fine
aggregate at 25, 50, 75, and 100% by weight of natural sand. A series
of tests was carried out to study the effect of using recycled aggregate
on the physical and mechanical properties of bricks, such as density,
drying shrinkage, water absorption characteristic, compressive and
flexural strength. Test results indicate that it is possible to
manufacture bricks containing recycled fine aggregate with good
characteristics that are similar in physical and mechanical properties
to those of bricks with natural aggregate, provided that the percentage
of recycled fine aggregates is limited up to 50-75%.