Miniaturized Microstrip Filter Design Using Active Learning Method

Relating coupling and external quality factor of a filter to the physical parameters of the structure which is the final step of any filter design is usually complicated due to geometrical complexities of the filter, or in the case of microstrip resonators due to the lack of the exact solution for the field distribution. Therefore, common approach is using time consuming full wave simulations. In this paper active learning method (ALM) which is a fuzzy-based modeling technique developed by a procedure algorithmically mimics the information-handling process of the human brain, is proposed to overcome this drawback. Modeling steps of an unknown function using ALM will be described using an illustrative example. Afterwards, the modeling approach will be implemented to model coupling factor between two coupled spiral resonators (SRs) for two different coupling structures and external quality factor of the same resonator. Accuracy of the extracted surfaces is validated using two different criteria. Using the extracted surfaces; a four pole chebychev bandpass filter was designed and fabricated. Good agreement between the measured response and simulation validated the accuracy of the extracted surfaces again. Comparing the fabricated SR filter with a square open loop resonator (SOLR) one demonstrates more than 70% of filter area reduction

Production performance of hydraulic fractures in tight gas sands, a numerical simulation approach. Journal of Petroleum Science and Engineering

Hydraulically fractured tight gas reservoirs are one of the most common unconventional gas sources being produced today, and will be a regular source of gas in the future. The extremely low permeability of tight gas sands leads to inaccuracy of conventional build-up and draw-down well test results. This is primarily due to the increased time required for transient flow in tight gas sands to reach pseudo-steady state condition. To increase accuracy, well tests for tight gas reservoirs must be run for longer periods of time which is in most cases not economically viable. The large amount of downtime required to conduct well tests in tight sands makes them far less economical than conventional reservoirs, which leads to the need for accurate simulation of tight gas reservoir well tests. This paper presents simulation results of a 3-D hydraulically fractured tight gas model created using Eclipse software. The key aims are to analyze the effect of differing fracture orientation, number and length. The focus of the simulation runs will be on the effect of hydraulic fracture orientation and length. The results will be compared to simulation runs without the abovementioned factors to determine their effects on production rates and well performance analysis. All results are plotted alongside an un-fractured tight gas scenario in order to put the hydraulic fracture performance in perspective. Key findings from this work include an approximately linear relationship between initial gas rate and the number of hydraulic fractures intersecting the wellbore. In addition, fracture length is found to have less of an impact on initial gas rate compared to number of fractures intersecting the wellbore, for comparable total fracture volumes

Characterizing natural fractures productivity in tight gas Reservoirs

Tight formations normally have production problems mainly due to very low matrix permeability and various forms of formation damage that occur during drilling completion and production operation. In naturally fractured tight gas reservoirs, gas is mainly stored in the rock matrix with very low permeability, and the natural fractures have the main contribution on total gas production. Therefore, identifying natural fractures characteristics in the tight formations is essential for well productivity evaluations. Well testing and logging are the common tools employed to evaluate well productivity. Use of image log can provide fracture static parameters, and welltest analysis can provide data related to reservoir dynamic parameters. However, due to the low matrix permeability and complexity of the formation in naturally fractured tight gas reservoirs, welltest data are affected by long wellbore storage effect that masks the reservoir response to pressure change, and it may fail to provide dual-porosity dual-permeability models dynamic characteristics such as fracture permeability, fracture storativity ratio and interporosity flow coefficient.Therefore, application of welltest and image log data in naturally fractured tight gas reservoirs for meaningful results may not be well understood and the data may be difficult to interpret. This paper presents the estimation of fracture permeability in naturally fractured tight gas formations, by integration of welltest analysis results and image log data based on Kazemi’s simplified model. Reservoir simulation of dual-porosity and dual-permeability systems and sensitivity analysis are performed for different matrix and fracture parameters to understand the relationship between natural fractures parameters with welltest permeability. The simulation results confirmed reliability of the proposed correlation for fracture permeability estimation. A field example is also shown to demonstrate application of welltest analysis and image log data processing results in estimating average permeability of natural fractures for the tight gas reservoir

Dynamics of a vapour bubble near a thin elastic plate

Numerical and experimental results show that during the collapse phase of a vapor bubble near a rigid boundary, in the absence of strong buoyancy forces, a liquid micro jet is developed on the side of the bubble far from the rigid surface and directed towards it. Numerical and experimental results also show that, in the case of a bubble near a free surface, during the collapse phase of the bubble and in the absence of strong buoyancy forces, the vapor bubble is repelled by the free surface. In this case a liquid micro jet is developed on the closest side of the bubble to the free surface and is directed away from it. The dynamic behavior of a vapor bubble near a free surface leads to the idea that a vapor bubble during its growth and collapse phases near a deformable diaphragm may have a behavior similar to its behavior near a free surface. In this paper dynamics of a vapor bubble during its growth and collapse phases near a thin elastic plate is investigated. It has been shown that the growth and collapse of a vapor bubble generated due to a high local energy input causes considerable deformation on the nearby thin elastic plate. Different thin elastic plates with different thicknesses and different flexural rigidities are assumed and the dynamic behavior of a vapor bubble near each of these plates is investigated. Results show that during the growth and collapse of a vapor bubble near a thin elastic plate with a proper thickness and flexural rigidity, in the absence of strong buoyancy forces, a liquid micro jet may develop on the closest side of the bubble to the thin elastic plate and directed away from it.http://deepblue.lib.umich.edu/bitstream/2027.42/84307/1/CAV2009-final132.pd

Permeability Prediction from Mercury Injection Capillary Pressure: An Example from the Perth Basin, Western Australia

For shale gas reservoirs, permeability is one of the most important—and difficult—parameters to determine. Typical shale matrix permeabilities are in the range of 10 microdarcy–100 nanodarcy, and are heavily dependent on the presence of natural fractures for gas transmissibility. Permeability is a parameter used to measure the ability of a rock to convey fluid. It is directly related to porosity and depends on the pore geometry features, such as tortuosity, pore shape and pore connectivity. Consequently, rocks with similar porosity can exhibit different permeability. Generally, permeability is measured in laboratories using core plugs. In some cases, however, it is difficult to obtain suitable core plugs. In these instances, other approaches can be used to predict permeability, which are chiefly based on mathematical and theoretical models. The approach followed in this peer-reviewed paper is to correlate permeability with capillary pressure data from mercury injection measurements. The theoretical and empirical equations, introduced in the literature for various conventional and unconventional reservoir rocks, have been used to predict permeability. Estimated gas shale permeabilities are then compared with results from transient and steady state methods on small pieces of rocks embedded in a resin disk. The study also attempts to establish a suitable equation that is applicable to gas shale formations and to investigating the relationship between permeability and porosity

Concept analysis of palliative care in nursing: Introducing a hybrid model

Background and purpose: Palliative care is an important concept in nursing practice and in literature several definitions are suggested for this concept. This study aimed at analyzing the concept of palliative care and identifying its features, antecedents and consequences within Iran�s cultural context. Materials and methods: Hybrid model of concept analysis was used to clarify the meaning of palliative care. The three phases of a hybrid concept analysis included theoretical, fieldwork, and final analysis. In theoretical phase different databases including PubMed, CINAHL, Science direct, Google scholar, SID and Magiran were searched for related articles (published in 2003-2013). The search keywords were palliative care and nursing care in the titles and abstracts. In the fieldwork phase semistructured in-depth interviews were conducted through purposive sampling in eight nurses. In next step, by combining the two previous stages the final analysis was performed. Results: In final analytical phase, main themes were extracted including pain management, holistic care, spirituality based care and religious based care. Conclusion: The findings showed that palliative care is an important aspect of clinical practice. It is a holistic, humanistic and corporative care for promoting the quality of life of patients and their families that support them while considering physical, psychological, spiritual, religious, cultural and social aspects. This type of care is beneficial throughout life and also in difficult situations such as famine and it should not be used just for end-stage patients. © 2015 Mazandaran University of Medical Sciences. All rights reserved

Identification and Evaluation of Unconventional Hydrocarbon Reserves: Examples from Zagros and Central Iran Basins

It is notable that over the past decade, proven reserves of natural gas have dramatically increased as higher prices and advances in technology have turned previously unrecoverable resources into major sources of domestic production. Moreover, the decline in crude oil reserves has significantly slowed over the past decade. Therefore, there would be an end to the conventional hydrocarbon resources sooner or later and, in the meantime, global natural gas consumption is projected to grow 52% from about 108 Tcf in 2009 to about 163 Tcf in 2030, which is an annual increase of almost 2%. In addition, since natural gas combustion produces less CO2 than coal and other petroleum products, governments are encouraged to use it as an alternative to other fossil fuels to reduce greenhouse gas emissions. Shale gas accumulations, with a unique all in one nature, where all petroleum system elements reside in just one lithology, have become the focus of gas exploration strategies after recent successes in the Barnett Shale gas production. Meanwhile, significant advances in drilling and stimulation technologies have made gas shale attractive for development in many countries including Iran. The unconventional gas resources such as coal bed methane and gas trapped in shale are growing in importance. Such estimated reserves account for approximately 18% of total proven gas reserves. Shale formations in particular offer enormous potential for future production. This study compares several shale gas resources in different areas and highlights the possible potential unconventional resources in Iran

Disulfide-induced self-assembled targets:A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles

A modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol-modified probes, each of which specifically binds at one half of the target introduced SH groups at both ends of dsDNA. Continuous disulfide bond formation at 3' and 5' terminals of targets leads to the self-assembly of dsDNAs into the sulfur-rich and flexible products with different lengths. These products have a high affinity for the surface of Au-NPs and efficiently protect the surface from salt induced aggregation. To evaluate the assay efficacy, a small part of the citrus tristeza virus (CTV) genome was targeted, leading to a detection limit of about 5 x 10(-9) mol. L-1 over a linear ranged from 20 x 10(-9) to 10 x 10(-7) mol. L-1. This approach also exhibits good reproducibility and recovery levels in the presence of plant total RNA or human plasma total circulating RNA extracts. Self-assembled targets can be then sensitively distinguished from non-assembled or mismatched targets after gel electrophoresis. The disulfide reaction method and integrating self-assembled DNAs/RNAs targets with bare AuNPs as a sensitive indicator provide us a powerful and simple visual detection tool for a wide range of applications