In this article we studied two types of teeth, spherical and
conical one. We compared the results with a previous study for the
flat tooth. the study of stresses field under these three teeth show
that in the soft rocks we prefer to use conical to
oth because it is
easy to be Implanted in the rock, and this was confirmed by the
values of stresses under the tooth. Either in hard rock and due to
our need for big values of pressure to shatter the rock we prefer to
use spherical tooth because of its property of forming tow cons of
stresses under tooth and therefore can be good in drilling hard
rock..
A computational model of the fatigue crack initiation period on the helical gears
,with consideration of the heat treatment by carburization and friction effects, is presented.
In order to calculate the number of stress cycles required for the appe
arance of the initial
cracks, and study the influence of dynamic behavior. For this end, a dynamic model of gear
with two freedom degrees in torsion developed in Matlab and fatigue criteria are used. The
computational results are compared with those obtained using strain- life method. The
obtained results show that appearance of initial fatigue crack depends strongly on the
friction coefficient between the surfaces, heat treatment, and on the dynamic load.
This research aim to recognize relationship between stresses
and Self-efficacy at college education students in Albaath
university, It also aimed to recognizing the levels of self-efficacy
and life stresses at them, and known differences of means
on
stresses and Self-efficacy according to Specialization school. The
research sample consist of (186) student male and female at
college education in Albaath University. To achieve this aims, the
researcher used the following materials: Test stresses and selfefficacy
prepared by the researcher.
Ship collision accidents are considered of the most serious incidents, due to the
subsequent disastrous results both in terms of economic losses in ships and cargo, and the
loss of human life as well as the great environmental pollution caused by i
t. Therefore,
continuous efforts are being made by research centers in order to understand the structural
response of the hull as a result of these incidents and accurately analyzed.
This research is interested in assessing the residual structural strength of a ship
exposed to collision through the internal energy and the various structural stresses
generated within it. The case is modeled for an oil tanker exposed to collision by the
bulbous bow of another vessel moves at different speeds and different angles. The
structural strength of the middle section of the struck ship was analyzed based on the
numerical methods using Ansys Dynamic Explicit program. Which allowed the
development of a clear vision for the structural changes and internal stresses energy with
time during the collision process.
The main objective of this article is to study the influence of static and dynamic
behavior on the occurrence of contact fatigue on spur gear tooth. For this end, a dynamic
model of geared transmission in one degree of freedom, with Crossland crite
rion, are used.
The motion equation is analyzed step par step in the time in order to determine the
dynamic load in all contact points on teeth profile. In this way, the time-varying dynamic
loads on tooth flanks are determined and the subsurface stress components can be derived
from the classic Hertzian theory.
The study aimed to identify the effect of pressure on the professional performance of
journalists working in the economic field in Syrian newspapers.
To achieve the objectives of the study were two questions are as follows
- What are the main prof
essional pressures facing journalists working in the economic field
in Syrian newspapers?
-What is the relationship of these variables (workload, organizational structure,
wages and bonuses, labor relations) level of professional pressures facing journalists
working for the economic domain in the Syrian press.
And to answer the question the study was used "application form" the researcher
prepared included several axes, according to the objectives of the study, which included
research community all journalists working in the economic sphere, the Syrian central
newspapers (public and private), whether they are full-time to this work or part-time,
totaling from (197) journalist working in the economic field.
This paper aims to calculate regular classical and complementary, so regular total Ignaczak solutions coupled with temperature field ,occupying R3 , and with vanishing stresses and temperature on the boundary.
In Syria, Barley is grown under rainfed conditions in areas receive less than 300mm
(zones: 2, 3 and 4), which is characterized by limited water availability and large year to
year variability in both total rainfall and distribution . A biotic stre
sses such as drought,
cold, heat , salinity and biotic stresses in addition to low soil fertility and the traditional
methods in agriculture production are the limiting factors for barley productivity in
Syria. In these agro-climatic environments, landraces and their wild relatives are
considered to be very useful as main sources of genetic materials in breeding programs,
also its widely recognized that these materials could be an important source of useful
genetic variation. A study of the genetic structure of landraces may explain to what
extent their adaptation to harsh environments is associated with remote or continuous
introgression of H. spontaneum, and hence indicates an additional avenue to improve
barley yield and its stability in dry areas. The ability of pure lines to sustain yield and
stability in dry areas highly correlated with its heterogeneity. and the mixture of several
lines gave higher productivity than the pure line Arabi asswad.
The objectives of this work were to study the relationships between the genotype and
environment interaction, to evaluate and compare the performance of number of
populations and barleymixtures with pure barley lines under rainfed conditions (Zone2)
in Tel Hadya Research Station (35 Km South of Aleppo city).
The study also aimed to investigate the population dynamic behavior of three pure
lines of barley in pure stands and in mixtures, each pure line being selected from
landraces of three climatically/ ecologically different regions in Syria and Jordan.
The results showed that, in spit of the narrow genetic variation between the
experimental materials, the variations were very wide and obvious for most of the studid
characteristics, mainly on grain yield (3.25-5.17 ton/ha) and biological yield 7.4 – 11.9.
The variation was due to highly productive tillers, 1000 kernel weight and grain size as
well as the morphological and phenological characteristics. The environmental conditions
during the three seasons did not allow the evaluation of the reaction of the Mixtures and
Populations even though mixture 2, which consists of 1: 2: 1 of zanbaka, Arta and Wadi
Al-Hassa showed a very good performance in grain yield, biological yield and many other
characteristics such as grain weight, harvest index, threshing percentage, grain number
and grain weight. It is expected that pure lines will perform better in favorable and
stable conditions and mixtures and some populations will play a very important role
under stressed environments.
