Abstract: In the present paper, a set of parametric FE stress
analyses is carried out for two-planar welded tubular DKT-joints
under two different axial load cases. Analysis results are used to
present general remarks on the effect of geometrical parameters on
the stress concentration factors (SCFs) at the inner saddle, outer
saddle, toe, and heel positions on the main (outer) brace. Then a new
set of SCF parametric equations is developed through nonlinear
regression analysis for the fatigue design of two-planar DKT-joints.
An assessment study of these equations is conducted against the
experimental data; and the satisfaction of the criteria regarding the
acceptance of parametric equations is checked. Significant effort has
been devoted by researchers to the study of SCFs in various uniplanar
tubular connections. Nevertheless, for multi-planar joints
covering the majority of practical applications, very few
investigations have been reported due to the complexity and high
cost involved.
Abstract: Having a very many number of pipelines all over the
country, Iran is one of the countries consists of various ecosystems
with variable degrees of fragility and robusticity as well as
geographical conditions. This study presents a state-of-the-art method
to estimate environmental risks of pipelines by recommending
rational equations including FES, URAS, SRS, RRS, DRS, LURS
and IRS as well as FRS to calculate the risks. This study was carried
out by a relative semi-quantitative approach based on land uses and
HVAs (High-Value Areas). GIS as a tool was used to create proper
maps regarding the environmental risks, land uses and distances. The
main logic for using the formulas was the distance-based approaches
and ESI as well as intersections. Summarizing the results of the
study, a risk geographical map based on the ESIs and final risk score
(FRS) was created. The study results showed that the most sensitive
and so of high risk area would be an area comprising of mangrove
forests located in the pipeline neighborhood. Also, salty lands were
the most robust land use units in the case of pipeline failure
circumstances. Besides, using a state-of-the-art method, it showed
that mapping the risks of pipelines out with the applied method is of
more reliability and convenience as well as relative
comprehensiveness in comparison to present non-holistic methods for
assessing the environmental risks of pipelines. The focus of the
present study is “assessment" than that of “management". It is
suggested that new policies are to be implemented to reduce the
negative effects of the pipeline that has not yet been constructed
completely
Abstract: Fisheries management all around the world is
hampered by the lack, or poor quality, of critical data on fish
resources and fishing operations. The main reasons for the chronic
inability to collect good quality data during fishing operations is the
culture of secrecy common among fishers and the lack of modern
data gathering technology onboard most fishing vessels. In response,
OLRAC-SPS, a South African company, developed fisheries datalogging
software (eLog in short) and named it Olrac. The Olrac eLog
solution is capable of collecting, analysing, plotting, mapping,
reporting, tracing and transmitting all data related to fishing
operations. Olrac can be used by skippers, fleet/company managers,
offshore mariculture farmers, scientists, observers, compliance
inspectors and fisheries management authorities. The authors believe
that using eLog onboard fishing vessels has the potential to
revolutionise the entire process of data collection and reporting
during fishing operations and, if properly deployed and utilised,
could transform the entire commercial fleet to a provider of good
quality data and forever change the way fish resources are managed.
In addition it will make it possible to trace catches back to the actual
individual fishing operation, to improve fishing efficiency and to
dramatically improve control of fishing operations and enforcement
of fishing regulations.
Abstract: A biocompatible ferrofluid have been prepared by coprecipitation
of FeCl2.4H2O and FeCl3.6H2O under ultrasonic
irradiation and with NaOH as alkaline agent. Cystein was also used
as capping agent in the solution. Magnetic properties of the produced
ferrofluid were then determined by VSM test and magnetite
nanoparticles were characterized by XRD and TEM techniques. The
effect of surfactant to Fe ion weight ratio was also studied during this
project by using two different amount of Dextran. Results showed the
presence of a biocompatible superparamagnetic ferrofluid including
magnetite nanoparticles with particle size ranging under 20 nm. The
increase in the surfactant content results in the narrowing of the size
distribution and reduction of the particle size and more solution
stability.
Abstract: Establishing pumping stations is one of the most common ways of providing water from rivers. There are many issues involved in the design and operation of pumping stations most important of which is the problem of sedimentation. One of the significant issues which must be taken into consideration in designing pumping stations is the operation method and technical matters related to it. Safety and convenience of operation is one of the issues that must be always considered by the designer. Some of the major issues in making decisions regarding the type of design for the station are geographical condition, the location of the station and availability of experts in maintenance and operation of the station. Dimensions of the station must allow free movement for checking and operating pumps after installation of pumps and plumbing system.
Abstract: This paper at first presents approximate analytical
solutions for systems of fractional differential equations using the
differential transform method. The application of differential
transform method, developed for differential equations of integer
order, is extended to derive approximate analytical solutions of
systems of fractional differential equations. The solutions of our
model equations are calculated in the form of convergent series with
easily computable components. After that a drive-response
synchronization method with linear output error feedback is
presented for “generalized projective synchronization" for a class of
fractional-order chaotic systems via a scalar transmitted signal.
Genesio_Tesi and Duffing systems are used to illustrate the
effectiveness of the proposed synchronization method.
Abstract: Cyprus- offshore aquaculture industry has promising
prospects taking into account that Cyprus is an island. Its production
trend is increasing overtaking bigger countries such Greece and Italy.
However, current mooring systems seem to be under-performing
acting as obstacles for its future development. Furthermore, shallow
coastal waters scarcity due to competing industries dictates future
development to come by moving further from shore exposing fish
farms and subsequently mooring systems to harsher environmental
loadings. It is, therefore, of paramount importance to design mooring
systems based on engineering and scientific principles and leave
behind the present “trial and error" methods. This paper presents the
current state of Cyprus- offshore aquaculture industry and focuses of
its mooring designs by proposing a new methodology for designing
more reliable systems, hence ensuring its future.
Abstract: Nowadays, offshore's complicated facilities need their
own communications requirements. Nevertheless, developing and
real-world applications of new communications technology are faced
with tremendous problems for new technology users, developers and
implementers. Traditional systems engineering cannot be capable to
develop a new technology effectively because it does not consider
the dynamics of the process. This paper focuses on the design of a
holistic model that represents the dynamics of new communication
technology development within offshore industry. The model shows
the behavior of technology development efforts. Furthermore,
implementing this model, results in new and useful insights about the
policy option analysis for developing a new communications
technology in offshore industry.
Abstract: Steel corrosion in concrete is considered as a main
engineering problems for many countries and lots of expenses has been paid for their repair and maintenance annually. This problem
may occur in all engineering structures whether in coastal and offshore or other areas. Hence, concrete structures should be able to
withstand corrosion factors existing in water or soil. Reinforcing
steel corrosion enhancement can be measured by use of concrete
electrical resistance; and maintaining high electric resistivity in concrete is necessary for steel corrosion prevention. Lots of studies
devoted to different aspects of the subjects worldwide. In this paper, an evaluation of the effects of W/C ratio, cementitious materials, and
percent increase in silica fume were investigated on electric resistivity of high strength concrete. To do that, sixteen mix design
with one aggregate grading was planned. Five of them had varying amount of W/C ratio and other eleven mixes was prepared with
constant W/C ratio but different amount of cementitious materials.
Silica fume and super plasticizer were used with different proportions
in all specimens. Specimens were tested after moist curing for 28 days. A total of 80 cube specimens (50 mm) were tested for concrete
electrical resistance. Results show that concrete electric resistivity can be increased with increasing amount of cementitious materials
and silica fume.
Abstract: Minimally invasive surgery (MIS) is now being widely used as a preferred choice for various types of operations. The need to detect various tactile properties, justifies the key role of tactile sensing that is currently missing in MIS. In this regard, Laparoscopy is one of the methods of minimally invasive surgery that can be used in kidney stone removal surgeries. At this moment, determination of the exact location of stone during laparoscopy is one of the limitations of this method that no scientific solution has been found for so far. Artificial tactile sensing is a new method for obtaining the characteristics of a hard object embedded in a soft tissue. Artificial palpation is an important application of artificial tactile sensing that can be used in different types of surgeries. In this study, a new method for determining the exact location of stone during laparoscopy is presented. In the present study, the effects of stone existence on the surface of kidney were investigated using conceptual 3D model of kidney containing a simulated stone. Having imitated palpation and modeled it conceptually, indications of stone existence that appear on the surface of kidney were determined. A number of different cases were created and solved by the software and using stress distribution contours and stress graphs, it is illustrated that the created stress patterns on the surface of kidney show not only the existence of stone inside, but also its exact location. So three-dimensional analysis leads to a novel method of predicting the exact location of stone and can be directly applied to the incorporation of tactile sensing in artificial palpation, helping surgeons in non-invasive procedures.
Abstract: Environment-assisted cracking (EAC) is one of the most serious causes of structural failure over a broad range of industrial applications including offshore structures. In EAC condition there is not a definite relation such as Paris equation in Linear Elastic Fracture Mechanics (LEFM). According to studying and searching a lot what the researchers said either a material has contact with hydrogen or any other corrosive environment, phenomenon of electrical and chemical reactions of material with its environment will be happened. In the literature, there are many different works to consider fatigue crack growing and solve it but they are experimental works. Thus, in this paper, authors have an aim to evaluate mathematically the pervious works in LEFM. Obviously, if an environment is more sour and corrosive, the changes of stress intensity factor is more and the calculation of stress intensity factor is difficult. A mathematical relation to deal with the stress intensity factor during the diffusion of sour environment especially hydrogen in a marine pipeline is presented. By using this relation having and some experimental relation an analytical formulation will be presented which enables the fatigue crack growth and critical crack length under cyclic loading to be predicted. In addition, we can calculate KSCC and stress intensity factor in the pipeline caused by EAC.
Abstract: The oil and gas industry has moved towards Load and
Resistance Factor Design through API RP2A - LRFD and the
recently published international standard, ISO-19902, for design of
fixed steel offshore structures. The ISO 19902 is intended to provide
a harmonized design practice that offers a balanced structural fitness
for the purpose, economy and safety. As part of an ongoing work, the
reliability analysis of tubular joints of the jacket structure has been
carried out to calibrate the load and resistance factors for the design
of offshore platforms in Malaysia, as proposed in the ISO.
Probabilistic models have been established for the load effects (wave,
wind and current) and the tubular joints strengths. In this study the
First Order Reliability Method (FORM), coded in MATLAB
Software has been employed to evaluate the reliability index of the
typical joints, designed using API RP2A - WSD and ISO 19902.