Abstract: Vertical ZnO nanowire array films were synthesized
based on aqueous method for sensing applications. ZnO nanowires
were investigated structurally using X-ray diffraction (XRD) and
scanning electron microscopy (SEM). The gas-sensing properties of
ZnO nanowires array films are studied. It is found that the ZnO
nanowires array film sensor exhibits excellent sensing properties
towards O2 and CO2 at 100 °C with the response time shorter than 5
s. High surface area / volume ratio of vertical ZnO nanowire and high
mobility accounts for the fast response and recovery. The sensor
response was measured in the range from 100 to 500 ppm O2 and CO2
in this study.
Abstract: Digital watermarking in medical images can ensure
the authenticity and integrity of the image. This design paper reviews
some existing watermarking schemes and proposes a reversible
tamper detection and recovery watermarking scheme. Watermark
data from ROI (Region Of Interest) are stored in RONI (Region Of
Non Interest). The embedded watermark allows tampering detection
and tampered image recovery. The watermark is also reversible and
data compression technique was used to allow higher embedding
capacity.
Abstract: In this work, several ASP solutions were flooded into
fractured models initially saturated with heavy oil at a constant flow
rate and different geometrical characteristics of fracture. The ASP
solutions are constituted from 2 polymers i.e. a synthetic polymer,
hydrolyzed polyacrylamide as well as a biopolymer, a surfactant and
2types of alkaline. The results showed that using synthetic
hydrolyzed polyacrylamide polymer increases ultimate oil recovery;
however, type of alkaline does not play a significant rule on oil
recovery. In addition, position of the injection well respect to the
fracture system has remarkable effects on ASP flooding. For instance
increasing angle of fractures with mean flow direction causes more
oil recovery and delays breakthrough time. This work can be
accounted as a comprehensive survey on ASP flooding which
considers most of effective factors in this chemical EOR method.
Abstract: In this work, the precipitation of asphaltene from a Malaysian light oil reservoir was studies. A series of experiments were designed and carried out to examine the effect of CO2 injection on asphaltene precipitation. Different pressures of injections were used in Dynamic flooding experiment in order to investigate the effect of pressure versus injection pore volume of CO2. These dynamic displacement tests simulate reservoir condition. Results show that by increasing the pore volume of injected gas asphaltene precipitation will increases, also rise in injection pressure causes less precipitation. Sandstone core plug was used to represent reservoir formation during displacement test; therefore it made it possible to study the effect of present of asphaltene on formation. It is found out that the precipitated asphaltene can reduce permeability and porosity which is not favorable during oil production.
Abstract: Authentication of multimedia contents has gained much attention in recent times. In this paper, we propose a secure semi-fragile watermarking, with a choice of two watermarks to be embedded. This technique operates in integer wavelet domain and makes use of semi fragile watermarks for achieving better robustness. A self-recovering algorithm is employed, that hides the image digest into some Wavelet subbands to detect possible malevolent object manipulation undergone by the image (object replacing and/or deletion). The Semi-fragility makes the scheme tolerant for JPEG lossy compression as low as quality of 70%, and locate the tempered area accurately. In addition, the system ensures more security because the embedded watermarks are protected with private keys. The computational complexity is reduced using parameterized integer wavelet transform. Experimental results show that the proposed scheme guarantees the safety of watermark, image recovery and location of the tempered area accurately.
Abstract: This research deals with techno economic analysis to select the most economic desalination method for Asalouyeh combined cycle power plant . Due to lack of fresh water, desalination of sea water is necessary to provide required DM water of Power Plant. The most common desalination methods are RO, MSF, MED, and MED–TVC. In this research, methods of RO, MED, and MED– TVC have been compared. Simulation results show that recovery of heat of exhaust gas of main stack is optimum case for providing DM water required for injected steam of MED desalination. This subject is very important because of improving thermal efficiency of power plant using extra heat recovery. Also, it has been shown that by adding 3 rows of finned tube to de-aerator evaporator, which is very simple and low cost, required steam for generating 5200 m3/day of desalinated water is obtainable.
Abstract: Simultaneous recovery of copper and DCA from
simulated MEUF concentrated stream was investigated. Effects of
surfactant (DCA) and metal (copper) concentrations, surfactant to
metal molar ratio (S/M ratio), electroplating voltage, EDTA
concentration, solution pH, and salt concentration on metal recovery
and current efficiency were studied. Electric voltage of -0.5 V was
shown to be optimum operation condition in terms of Cu recovery,
current efficiency, and surfactant recovery. Increasing Cu recovery and
current efficiency were observed with increases of Cu concentration
while keeping concentration of DCA constant. However, increasing
both Cu and DCA concentration while keeping S/M ratio constant at
2.5 showed detrimental effect on Cu recovery at DCA concentration
higher than 15 mM. Cu recovery decreases with increasing pH while
current efficiency showed an opposite trend. It is believed that
conductivity is the main cause for discrepancy of Cu recovery and
current efficiency observed at different pH. Finally, it was shown that
EDTA had adverse effect on both Cu recovery and current efficiency
while addition of NaCl salt had negative impact on current efficiency
at concentration higher than 8000 mg/L.
Abstract: In this paper, we propose a reversible watermarking
scheme based on histogram shifting (HS) to embed watermark bits
into the H.264/AVC standard videos by modifying the last nonzero
level in the context adaptive variable length coding (CAVLC) domain.
The proposed method collects all of the last nonzero coefficients (or
called last level coefficient) of 4×4 sub-macro blocks in a macro
block and utilizes predictions for the current last level from the
neighbor block-s last levels to embed watermark bits. The feature of
the proposed method is low computational and has the ability of
reversible recovery. The experimental results have demonstrated that
our proposed scheme has acceptable degradation on video quality and
output bit-rate for most test videos.
Abstract: The modified Claus process is commonly used in oil
refining and gas processing to recover sulfur and destroy
contaminants formed in upstream processing. A Claus furnace feed
containing a relatively low concentration of H2S may be incapable of
producing a stable flame. Also, incomplete combustion of
hydrocarbons in the feed can lead to deterioration of the catalyst in
the reactors due to soot or carbon deposition. Therefore, special
consideration is necessary to achieve the appropriate overall sulfur
recovery. In this paper, some configurations available to treat lean
acid gas streams are described and the most appropriate ones are
studied to overcome low H2S concentration problems. As a result,
overall sulfur recovery is investigated for feed preheating and hot gas
configurations.
Abstract: As global industry developed rapidly, the energy
demand also rises simultaneously. In the production process, there’s a
lot of energy consumed in the process. Formally, the energy used in
generating the heat in the production process. In the total energy
consumption, 40% of the heat was used in process heat, mechanical
work, chemical energy and electricity. The remaining 50% were
released into the environment. It will cause energy waste and
environment pollution. There are many ways for recovering the waste
heat in factory. Organic Rankine Cycle (ORC) system can produce
electricity and reduce energy costs by recovering the waste of low
temperature heat in the factory. In addition, ORC is the technology
with the highest power generating efficiency in low-temperature heat
recycling. However, most of factories executives are still hesitated
because of the high implementation cost of the ORC system, even a lot
of heat are wasted. Therefore, this study constructs a nonlinear
mathematical model of waste heat recovery equipment configuration
to maximize profits. A particle swarm optimization algorithm is
developed to generate the optimal facility installation plan for the ORC
system.
Abstract: In the Enhanced Oil Recovery (EOR) method, use of Carbon dioxide flooding whereby CO2 is injected into an oil reservoir to increase output when extracting oil resulted significant recovery worldwide. The carbon dioxide function as a pressurizing agent when mixed into the underground crude oil will reduce its viscosity and will enable a rapid oil flow. Despite the CO2’s advantage in the oil recovery, it may result to asphaltene precipitation a problem that will cause the reduction of oil produced from oil wells. In severe cases, asphaltene precipitation can cause costly blockages in oil pipes and machinery. This paper presents reviews of several studies done on mathematical modeling of asphaltene precipitation. The synthesized result from several researches done on this topic can be used as guide in order to better understand asphaltene precipitation. Likewise, this can be used as initial reference for students, and new researchers doing study on asphaltene precipitation.
Abstract: The article deals with technical support of intracranial single unit activity measurement. The parameters of the whole measuring set were tested in order to assure the optimal conditions of extracellular single-unit recording. Metal microelectrodes for measuring the single-unit were tested during animal experiments. From signals recorded during these experiments, requirements for the measuring set parameters were defined. The impedance parameters of the metal microelectrodes were measured. The frequency-gain and autonomous noise properties of preamplifier and amplifier were verified. The measurement and the description of the extracellular single unit activity could help in prognoses of brain tissue damage recovery.
Abstract: Although lots of experiments have been done in enhanced oil recovery, the number of experiments which consider the effects of local and global heterogeneity on efficiency of enhanced oil recovery based on the polymer-surfactant flooding is low and rarely done. In this research, we have done numerous experiments of water flooding and polymer-surfactant flooding on a five spot glass micromodel in different conditions such as different positions of layers. In these experiments, five different micromodels with three different pore structures are designed. Three models with different layer orientation, one homogenous model and one heterogeneous model are designed. In order to import the effect of heterogeneity of porous media, three types of pore structures are distributed accidentally and with equal ratio throughout heterogeneous micromodel network according to random normal distribution. The results show that maximum EOR recovery factor will happen in a situation where the layers are orthogonal to the path of mainstream and the minimum EOR recovery factor will happen in a situation where the model is heterogeneous. This experiments show that in polymer-surfactant flooding, with increase of angles of layers the EOR recovery factor will increase and this recovery factor is strongly affected by local heterogeneity around the injection zone.