A Sawtooth Permanent Magnetic Lattice for Ultracold Atoms and BECs

We propose a new permanent magnetic lattice for creating periodic arrays of Ioffe-Pritchard permanent magnetic microtraps for holding and controlling ultracold atoms and Bose-Einstein condensates (BECs). Lattice can be designed on thin layer of magnetic films such as $Tb_6$$Gd_10$$Fe_{80}$$Co_4$. In details, we investigate single layer and two crossed layers of sawtooth magnetic patterns with thicknesses of 50 and 500nm respectively with a periodicity of 1$\mu$m. Trap depth and frequencies can be changed via an applied bias field to handle tunneling rates between lattice sites. We present analytical expressions and using numerical calculations show that this lattice has non-zero potential minima to avoid majorana spin flips. One advantage of this lattice over previous ones is that it is easier to manufacture.Comment: 8 pages, 6 figure

Comparison of CO2-EOR performance between offshore and onshore classes of reservoirs

CO2 has been extensively used in onshore fields, primarily for EOR. However, it has been used less offshore due to limited transportation infrastructure and the lack of secure CO2 supply. Recently, CO2 flooding has been reconsidered in offshore fields for both EOR and storage. The performance of CO2 flooding in the offshore classes of reservoirs, which are characterised by fundamentally dissimilar properties and development characteristics than onshore reservoirs, might be different from the past experience of CO2 flooding observed onshore. Offshore developments are characterised by higher rates of depletion, fewer wells, larger well spacing and higher well rates compared to onshore reservoirs which are characterised by pattern development and shorter well spacings; moreover, the motivation behind CO2 flooding might be different offshore. The aim of this study is to review these differences between CO2 flooding in offshore and onshore classes of reservoirs, exclusively within the context of reservoir engineering. In the first part of this study, different aspects of CO2 flooding are compared between two major provinces i.e. the onshore Permian Basin province located in the United States and the offshore North Sea province. It will be shown that CO2-EOR has many similar characteristics in these two provinces despite the fact that ambient reservoir conditions are fundamentally different between them. Next, flow patterns are compared between these two classes of reservoirs. Flow patterns in each of reservoirs are investigated by deriving the key dimensionless numbers which may characterise CO2 flooding in each of them. It will be shown that CO2 flooding is slightly more gravity dominated in the North Sea class of reservoirs. Additionally, in the absence of gravity effects, flow patterns upon CO2 flooding are expected to be more stable in the North Sea class of reservoirs due to better mobility ratios that characterise the displacement in this province. The fact that the motivation for CO2 flooding is potentially different between these two classes of reservoir may also promote alternate CO2 flooding process designs offshore, which should satisfy both the EOR and storage requirements of CO2 flooding in the offshore class of reservoirs. The second part of this thesis investigates the grid size requirements for modelling miscible processes such as CO2-EOR. A new approach based on measuring heterogeneity induced dispersivities in longitudinal and transverse orientations is introduced and developed. Matching these dispersivities with equivalent numerical dispersion may determine the correct size of grid blocks in a miscible displacement simulation

development of a high-performance pressure swing sorption process for natural gas dehydration

Natural gas is an important energy source for industry, transportation, and homes. It is also used as a chemical feedstock in the manufacturing of plastics and other commercially important organic chemicals. The presence of water in natural gas not only substantially decreases the heating value of natural gas, but also damages the transportation pipeline by corrosion and methane hydrate formation. To dehydrate natural gas, technologies such as absorption, adsorption, condensation, and supersonic separation have been developed. Despite satisfactory results from these technologies, problems with pollution and high processing costs still exist. In this research project, a new pressure swing sorption process for dehydration of gases using biosorbents was developed, which is efficient, environmentally friendly, and economically favorable. Biosorbents were made from flax shives and oat hulls, which had high water vapor sorption capacity and selectivity compared to numerous commercial adsorbents. Six-step and four-step PSA cycles were designed and dual-column pressure swing experiments were conducted. The process worked for over 450 cycles without observable degradation and pipeline-quality dry gas was achieved. Equilibrium and kinetic modeling were performed to further investigate the water vapor sorption characteristics and mechanisms. In addition, the properties of the biosorbents such as sorption capacity, selectivity, pore size and pore volume distributions, surface functional groups, packing and true densities, thermal stability, and biopolymer/elemental compositions were determined. Furthermore, a life cycle assessment was performed to compare the environmental impacts of biosorbent production with those of molecular sieves production. The results showed that both the PSA process and the biosorbents developed in this work are environmentally friendly and efficient, and have a potential for industrial applications such as dehydration of natural gas, biogas, syngas, and air. The value propositions of the developed process are efficient gas dehydration with low negative environmental impacts and a potential market for agricultural residues as industrial biosorbents in this process

Evaluation of Persian Academy approved genetics terms acceptance in upper graduate user population

Finding Persian equivalents for scientific terms is one of the aims of Academy of Persian language and literature, and more than 50 scientific committees are now working on this scope in terminology department of the academy. Genetics and biotechnology terminology committee is one of these teams that started his activity from 2009 and since then approved more than 500 of these terms for use in academic fields. In this research 101 questionnaires including 20 questioned term were given to more than 101 upper graduate users including MSc and PhD students and academic staff of randomly selected universities in Tehran and Semnan provinces. And then the evaluation of their acceptance was carried out by a model given by Cooper for the Study of Language Spread. All 20 studied terms were randomly selected from genetic approved terms and divided in to two groups: newly coined equivalents (those equivalents that was newly coined by the committee) and selected equivalents (those that have the selected equivalent before).Results gathered and analyzed with statistical tests, and showed that most of accepted terms are among selected equivalents. By another words the newly coined terms has much less acceptability than the others. This research introduces a method for evaluation of approved Persian equivalents of scientific terms and besides show the state of some of these equivalents between user populations. The important point is that term selection for scientific terms including genetic terms; is not an obligatory rule, but is a proposal for meeting the researchers need to strength Persian language as a scientific language. And usage of these equivalents is completely on the part of researchers and students and their point of view to equivalents.

A statistical study of the luminosity gap in galaxy groups

The luminosity gap between the two brightest members of galaxy groups and clusters is thought to offer a strong test for the models of galaxy formation and evolution. This study focuses on the statistics of the luminosity gap in galaxy groups, in particular fossil groups, e.g. large luminosity gap, in an analogy with the same in a cosmological simulation. We use spectroscopic legacy data of seventh data release (DR7) of SDSS, to extract a volume limited sample of galaxy groups utilizing modified friends-of-friends (mFoF) algorithm. Attention is paid to galaxy groups with the brightest group galaxy (BGG) more luminous than \Mr = -22. An initial sample of 620 groups in which 109 optical fossil groups, where the luminosity gap exceeds 2 magnitude, were identified. We compare the statistics of the luminosity gap in galaxy groups at low mass range from the SDSS with the same in the Millennium simulations where galaxies are modeled semi-analytically. We show that the BGGs residing in galaxy groups with large luminosity gap, i.e. fossil groups, are on average brighter and live in lower mass halos with respect to their counter parts in non-fossil systems. Although low mass galaxy groups are thought to have recently formed, we show that in galaxy groups with 15 galaxies brighter than $M_r\ge -19.5$, evolutionary process are most likely to be responsible for the large luminosity gap. We also examine a new probe of finding fossil group. In addition we extend the recently introduced observational probe based on the luminosity gap, the butterfly diagram, to galaxy groups and study the probe as a function of halo mass. This probe can, in conjunction with the luminosity function, help to fine tune the semi-analytic models of galaxies employed in the cosmological simulations.Comment: 11 pages, 11 figures, accepted to PASP journa

The impact of background water flow on the early migration of a CO2 plume in a tilted aquifer during the post-injection period

The study presents a numerical modelling analysis on CO2 plume migration in a dipping storage aquifer with background flux, which incorporates residual and dissolution trapping of CO2. The purpose of this analysis is to investigate the effect of the background flow velocity on the CO2 plume migration during the early post-injection period. Different velocities of groundwater flow from low to high were considered in the aquifer model. The distribution, migration distance and velocity of the injected CO2 plume as well as the remaining mobile CO2 plume extent are estimated to determine how fast and far the plume propagates with time. Comparison of the results indicate that increasing the background flux velocity causes the plume to migrate longer distances up-dip, while it reduces the height distribution of the plume with time. This reduces the volume of mobile CO2 in the storage aquifer at larger velocities of background flux, hence decreasing the leakage risk of CO2 to the surface. In addition, the CO2 plume decelerates immediately after cessation of injection as its bottom rises vertically and the buoyancy force reduces as the thickness of the plume reduces. However, the plume then accelerates during the initial period of its subsequent lateral migration, as the plume becomes extended, and the buoyancy forces increases somewhat. The degree of lateral extension increases with increasing background water flow velocity, with the leading tip of the plume migrating faster than the trailing edge, until residual and dissolution trapping sufficiently reduce the volume of free phase CO2 that its migration is arrested.Document Type: Original articleCited as: Awag, M., Mackay, E., Ghanbari, A. The impact of background water flow on the early migration of a CO2 plume in a tilted aquifer during the post-injection period. Advances in Geo-Energy Research, 2023, 9(2): 125-135. https://doi.org/10.46690/ager.2023.08.0