Abstract: Heavy metals have a damaging impact for the environment, animals and humans due to their extreme toxicity and removing them from wastewaters is a very important and interesting task in the field of water pollution control. Biosorption is a relatively new method for treatment of wastewaters and recovery of heavy metals. In this study, a continuous fixed bed study was carried out by using Bacillus thuringiensis as a biosorbent for the removal of Cu and Mn ions from Sarcheshmeh Acid Mine Drainage (AMD). The effect of operating parameters such as flow rate and bed height on the sorption characteristics of B. thuringiensis was investigated at pH 6.0 for each metal ion. The experimental results showed that the breakthrough time decreased with increasing flow rate and decreasing bed height. The data also indicated that the equilibrium uptake of both metals increased with decreasing flow rate and increasing bed height. BDST, Thomas, and Yoon–Nelson models were applied to experimental data to predict the breakthrough curves. All models were found suitable for describing the whole dynamic behavior of the column with respect to flow rate and bed height. In order to regenerate the adsorbent, an elution step was carried out with 1 M HCl and five adsorption-desorption cycles were carried out in continuous manner.
Abstract: The discharge of dye in industrial effluents is of great concern because their presence and accumulation have a toxic or carcinogenic effect on living species. The removal of such compounds at such low levels is a difficult problem. The adsorption process is an effective and attractive proposition for the treatment of dye contaminated wastewater. Activated carbon adsorption in fixed beds is a very common technology in the treatment of water and especially in processes of decolouration. However, it is expensive and the powdered one is difficult to be separated from aquatic system when it becomes exhausted or the effluent reaches the maximum allowable discharge level. The regeneration of exhausted activated carbon by chemical and thermal procedure is also expensive and results in loss of the sorbent. The focus of this research was to evaluate the adsorption potential of the raw clay in removing rhodamine B from aqueous solutions using a laboratory fixed-bed column. The continuous sorption process was conducted in this study in order to simulate industrial conditions. The effect of process parameters, such as inlet flow rate, adsorbent bed height, and initial adsorbate concentration on the shape of breakthrough curves was investigated. A glass column with an internal diameter of 1.5 cm and height of 30 cm was used as a fixed-bed column. The pH of feed solution was set at 8.5. Experiments were carried out at different bed heights (5 - 20 cm), influent flow rates (1.6- 8 mL/min) and influent rhodamine B concentrations (20 - 80 mg/L). The obtained results showed that the adsorption capacity increases with the bed depth and the initial concentration and it decreases at higher flow rate. The column regeneration was possible for four adsorption–desorption cycles. The clay column study states the value of the excellent adsorption capacity for the removal of rhodamine B from aqueous solution. Uptake of rhodamine B through a fixed-bed column was dependent on the bed depth, influent rhodamine B concentration, and flow rate.
Abstract: This study reports a comparison from an exergetic point of view between three configurations of vapor compression industrial refrigeration systems operating with R134a as working fluid. The performances of the different cycles are analyzed as function of several operating parameters such as condensing temperature and inter stage pressure. In addition, the contributions of component exergy destruction to the total exergy destruction are obtained for each system. The results are estimated to be used in the selection of the most advantageous configuration from an exergetic view point.
Abstract: We investigate the performance of an integrated cascade (IC) refrigeration system which uses environment friendly zeotropic mixtures. Computational calculation has been carried out by varying pressure level at the evaporator and the condenser of the system. Effects of mass flow rate of the refrigerant on the coefficient of performance (COP) are presented. We show that the integrated cascade system produces ultra-low temperatures in the evaporator by using environment friendly zeotropic mixture.
Abstract: In this study, thermal fatigue properties of 400 series
ferritic stainless steels have been evaluated in the temperature ranges
of 200-800oC and 200-900oC. Systematic methods for control of
temperatures within the predetermined range and measurement of load
applied to specimens as a function of temperature during thermal
cycles have been established. Thermal fatigue tests were conducted
under fully constrained condition, where both ends of specimens were
completely fixed. It has been revealed that load relaxation behavior at
the temperatures of thermal cycle was closely related with the thermal
fatigue property. Thermal fatigue resistance of 430J1L stainless steel
is found to be superior to the other steels.
Abstract: Asphalt pavement itself is a mixture made up of mainly aggregates, binders, and fillers that acts as a composition used for pavement construction. An experimental program was setup to determine the fatigue performance test of Asphalt with three different grades of conventional binders. Asphalt specimen has achieved the maximum optimum bulk density and air voids with a consistent bulk density of 2.3 t/m3, with an air void of 5% ± 0.5, before loading into the Asphalt Mixture Performance Tested (AMPT) for fatigue test. The number of cycles is defined as the point where phase angle drops, which is caused by the formation of cracks due to the increasing micro cracks when asphalt is undergoing repeated cycles of loading. Thus, the data collected are analyzed using the drop of phase angle as failure criteria. Based in the data analyzed, it is evident that the fatigue life of asphalt lies on the grade of binder. The result obtained shows that all specimens do experience a drop in phase angle due to macro cracks in the asphalt specimen.
Abstract: Over the last two decades, externally bonded fiber
reinforced polymer (FRP) composites bonded to concrete substrates
has become a popular method for strengthening reinforced concrete
(RC) highway and railway bridges. Such structures are exposed to
severe cyclic loading throughout their lifetime often resulting in
fatigue damage to structural components and a reduction in the
service life of the structure. Since experimental and numerical results
on the fatigue performance of FRP-to-concrete joints are still limited,
the current research focuses on assessing the fatigue performance of
externally bonded FRP-to-concrete joints using a direct shear test.
Some early results indicate that the stress ratio and the applied cyclic
stress level have a direct influence on the fatigue life of the externally
bonded FRP. In addition, a calibrated finite element model is
developed to provide further insight into the influence of certain
parameters such as: concrete strength, FRP thickness, number of
cycles, frequency, and stiffness on the fatigue life of the FRP-toconcrete
joints.
Abstract: This paper deals with using of prevailing operation
system MS Office (SmartArt...) for mathematical models, using
DYVELOP (Dynamic Vector Logistics of Processes) method. It
serves for crisis situations investigation and modelling within the
organizations of critical infrastructure. In first part of paper, it will be
introduced entities, operators, and actors of DYVELOP method. It
uses just three operators of Boolean algebra and four types of the
entities: the Environments, the Process Systems, the Cases, and the
Controlling. The Process Systems (PrS) have five “brothers”:
Management PrS, Transformation PrS, Logistic PrS, Event PrS and
Operation PrS. The Cases have three “sisters”: Process Cell Case,
Use Case, and Activity Case. They all need for the controlling of
their functions special Ctrl actors, except ENV – it can do without
Ctrl. Model´s maps are named the Blazons and they are able
mathematically - graphically express the relationships among entities,
actors and processes. In second part of this paper, the rich blazons of
DYVELOP method will be used for the discovering and modelling of
the cycling cases and their phases. The blazons need live PowerPoint
presentation for better comprehension of this paper mission. The
crisis management of energetic crisis infrastructure organization is
obliged to use the cycles for successful coping of crisis situations.
Several times cycling of these cases is necessary condition for the
encompassment for both emergency events and the mitigation of
organization´s damages. Uninterrupted and continuous cycling
process brings for crisis management fruitfulness and it is good
indicator and controlling actor of organizational continuity and its
sustainable development advanced possibilities. The research reliable
rules are derived for the safety and reliable continuity of energetic
critical infrastructure organization in the crisis situation.
Abstract: The transesterification of dimethyl malonate (DMM)
with phenol has been studied in vapour phase over cordierite
honeycomb coated with solid acid catalysts such as ZrO2,
Mo(VI)/ZrO2 and SO42-/ZrO2. The catalytic materials were prepared
honeycomb coated, powder forms, and characterized for their total
surface acidity by NH3-TPD and crystalinity by powder XRD
methods. Phenyl methyl malonate (PMM) and diphenyl malonate
(DPM) were obtained as the reaction products. A good conversion of
DMM (up to 82%) of MPM with 95% selectivity was observed when
the reactions were carried out at a catalyst bed temperature of 200 °C
and flow-rate of 10 mL/h in presence of Mo(VI)/ZrO2 as catalyst.
However, over SO4^2-/ZrO2 catalyst, the yield of DPM was found to be
higher. The results have been interpreted based on the variation of
acidic properties and powder XRD phases of zirconia on
incorporation of Mo(VI) or SO42– ions. Transesterification reactions
were also carried out over powder forms of the catalytic materials
and the yield of the desired phenyl ester products were compared
with that of the HC coated catalytic materials. The solid acids were
found to be reusable when used for at least 5 reaction cycles.
Abstract: Considering the challenges of short product life cycles
and growing variant diversity, cost minimization and manufacturing
flexibility increasingly gain importance to maintain a competitive
edge in today’s global and dynamic markets. In this context, an
aerodynamic part feeding system for high-speed industrial assembly
applications has been developed at the Institute of Production
Systems and Logistics (IFA), Leibniz Universitaet Hannover. The
aerodynamic part feeding system outperforms conventional systems
with respect to its process safety, reliability, and operating speed. In
this paper, a multi-objective optimisation of the aerodynamic feeding
system regarding the orientation rate, the feeding velocity, and the
required nozzle pressure is presented.
Abstract: A number of studies have been conducted recently to
investigate the influence of randomly oriented fibers on some
engineering properties of cohesive and cohesionless soils. However,
few studies have been carried out on freezing-thawing behavior of
fine-grained soils modified with discrete fiber inclusions and additive
materials. This experimental study was performed to investigate the
effect of randomly distributed polypropylene fibers (PP) and some
additive materials [e.g.., borogypsum (BG), fly ash (FA) and cement
(C)] on freezing-thawing durability (mass losses) of a fine-grained
soil for 6, 12, and 18 cycles. The Taguchi method was applied to the
experiments and a standard L9 orthogonal array (OA) with four
factors and three levels were chosen. A series of freezing-thawing
tests were conducted on each specimen. 0-20% BG, 0-20% FA, 0-
0.25% PP and 0-3% of C by total dry weight of mixture were used in
the preparation of specimens. Experimental results showed that the
most effective materials for the freezing-thawing durability (mass
losses) of the samples were borogypsum and fly ash. The values of
mass losses for 6, 12 and 18 cycles in optimum conditions were
16.1%, 5.1% and 3.6%, respectively.
Abstract: In order to be competitive, companies have to reduce
their production costs while meeting increasing quality requirements.
Therefore, companies try to plan their assembly processes as detailed
as possible. However, increasing product individualization leading to
a higher number of variants, smaller batch sizes and shorter product
life cycles raise the question to what extent the effort of detailed
planning is still justified. An important approach in this field of
research is the concept of determining the economic planning depth
for assembly process planning based on production specific
influencing factors. In this paper first solution hypotheses as well as a
first draft of the resulting method will be presented.
Abstract: Work presented is interested in the characterization of
the quasistatic mechanical properties and in fatigue of a composite
laminated in jute/epoxy. The natural fibers offer promising prospects
thanks to their interesting specific properties, because of their low
density, but also with their bio-deterioration. Several scientific
studies highlighted the good mechanical resistance of the vegetable
fiber composites reinforced, even after several recycling. Because of
the environmental standards that become increasingly severe, one
attends the emergence of eco-materials at the base of natural fibers
such as flax, bamboo, hemp, sisal, jute. The fatigue tests on
elementary vegetable fibers show an increase of about 60% of the
rigidity of elementary fibers of hemp subjected to cyclic loadings. In
this study, the test-tubes manufactured by the method infusion have
sequences of stacking of 0/90° and ± 45° for the shearing and tensile
tests. The quasistatic tests reveal a variability of the mechanical
properties of about 8%. The tensile fatigue tests were carried out for
levels of constraints equivalent to half of the ultimate values of the
composite. Once the fatigue tests carried out for well-defined values
of cycles, a series of static tests of traction type highlights the
influence of the number of cycles on the quasi-static mechanical
behavior of the laminate jute/epoxy.
Abstract: This contribution presents a friction estimator for
industrial purposes which identifies Coulomb friction in a steering
system. The estimator only needs a few, usually known, steering
system parameters. Friction occurs on almost every mechanical
system and has a negative influence on high-precision position
control. This is demonstrated on a steering angle controller for highly
automated driving. In this steering system the friction induces limit
cycles which cause oscillating vehicle movement when the vehicle
follows a given reference trajectory. When compensating the friction
with the introduced estimator, limit cycles can be suppressed. This
is demonstrated by measurements in a series vehicle.
Abstract: The using of waste materials in the construction
industry can reduce the dependence on the natural aggregates which
are going at the end to deplete. The glass waste is generated in a huge
amount which can make one of its disposals in concrete industry
effective not only as a green solution but also as an advantage to
enhance the performance of mechanical properties and durability of
concrete. This article reports the performance of concrete specimens
containing different percentages of milled glass waste as a partial
replacement of cement (Powder), when they are subject to cycles of
freezing and thawing. The tests were conducted on 75-mm cubes and
75 x 75 x 300-mm prisms. Compressive strength based on laboratory
testing and non-destructive ultrasonic pulse velocity test were
performed during the action of freezing-thawing cycles (F/T). The
results revealed that the incorporation of glass waste in concrete
mixtures is not only feasible but also showed generally better strength
and durability performance than control concrete mixture. It may be
said that the recycling of waste glass in concrete mixes is not only a
disposal way, but also it can be an exploitation in concrete industry.
Abstract: Durability of Membrane Electrode Assembly for
Proton Exchange Membrane Fuel Cells was evaluated in both steady
state and accelerated decay modes. Steady state mode was carried out
at constant current of 800mA/cm2 for 2500 hours using air as cathode
feed and pure hydrogen as anode feed. The degradation of the cell
voltage was 0.015V after such 2500 hrs operation. The degradation
rate was therefore calculated to be 6uV/hr. Continuously Vigorous
fluctuation of the cell voltage, which was switched between OCV and
0.2V, was employed for the accelerated decay mode. No obvious
change in performance of the MEA was observed after 10000 cycles
of such operation.
Abstract: The numerical simulation has made tremendous
advances in investigating the blood flow phenomenon through elastic
arteries. Such study can be useful in demonstrating the disease
progression and hemodynamics of cardiovascular diseases such as
atherosclerosis. In the present study, patient specific case diagnosed
with partially stenosed complete right ICA and normal left carotid
bifurcation without any atherosclerotic plaque formation is
considered. 3D patient specific carotid bifurcation model is generated
based on CT scan data using MIMICS-4.0 and numerical analysis is
performed using FSI solver in ANSYS-14.5. The blood flow is
assumed to be incompressible, homogenous and Newtonian, while
the artery wall is assumed to be linearly elastic. The two-way
sequentially coupled transient FSI analysis is performed using FSI
solver for three pulse cycles. The hemodynamic parameters such as
flow pattern, Wall Shear Stress, pressure contours and arterial wall
deformation are studied at the bifurcation and critical zones such as
stenosis. The variation in flow behavior is studied throughout the
pulse cycle. Also, the simulation results reveal that there is a
considerable increase in the flow behavior in stenosed carotid in
contrast to the normal carotid bifurcation system. The investigation
also demonstrates the disturbed flow pattern especially at the
bifurcation and stenosed zone elevating the hemodynamics,
particularly during peak systole and later part of the pulse cycle. The
results obtained agree well with the clinical observation and
demonstrates the potential of patient specific numerical studies in
prognosis of disease progression and plaque rupture.
Abstract: Knowledge of bone mechanical properties is important
for bone substitutes design and fabrication, and more efficient
prostheses development. The aim of this study is to characterize the
viscoelastic behavior of bone specimens, through stress relaxation
and fatigue tests performed to trabecular bone samples from bovine
femoral heads. Relaxation tests consisted on preloading the samples
at five different magnitudes and evaluate them for 1020 seconds,
adjusting the results to a KWW mathematical model. Fatigue tests
consisted of 700 load cycles and analyze their status at the end of the
tests. As a conclusion we have that between relaxation stress and
each preload there is linear relation and for samples with initial
Young´s modulus greater than 1.5 GPa showed no effects due fatigue
test loading cycles.
Abstract: Due to the increasing efforts on saving our natural
environment a change in the structure of energy resources can be
observed - an increasing fraction of a renewable energy sources.
In many countries traditional underground coal mining loses its
significance but there are still countries, like Poland or Germany, in
which the coal based technologies have the greatest fraction in a total
energy production. This necessitates to make an effort to limit the
costs and negative effects of underground coal mining. The longwall
complex is as essential part of the underground coal mining. The
safety and the effectiveness of the work is strongly dependent of the
diagnostic state of powered roof supports.
The building of a useful and reliable diagnostic system requires
a lot of data. As the acquisition of a data of any possible operating
conditions it is important to have a possibility to generate a demanded
artificial working characteristics. In this paper a new approach of
modelling a leg pressure in the single unit of powered roof support.
The model is a result of the analysis of a typical working cycles.
Abstract: The atmospheres in many cities along the coastal lines
in the world have been rapidly changed to coastal-industrial
atmosphere. Hence, it is vital to investigate the corrosion behavior of
steel exposed to this kind of environment. In this present study,
Electrochemical Impedance Spectrography (EIS) and film thickness
measurement were applied to monitor the corrosion behavior of
weathering steel covered with a thin layer of the electrolyte in a
wet-dry cyclic condition, simulating a coastal-industrial environment
at 25oC and 60% RH. The results indicate that in all cycles, the
corrosion rate increases during the drying process due to an increase in
anion concentration and an acceleration of oxygen diffusion enhanced
by the effect of the thinning out of the electrolyte. During the wet-dry
cyclic corrosion test, the long-term corrosion behavior of this steel
depends on the periods of exposure. Corrosion process is first
accelerated and then decelerated. The decelerating corrosion process is
contributed to the formation of the protective rust, favored by the
wet-dry cycle and the acid regeneration process during the rusting
process.