The aim of this paper is robust identification of SMART FOAM, as an electroacoustic transducer, considering un modelled dynamics due to nonlinearities in behaviour at low frequencies and measurement noise at high frequencies as existent uncertainties. Set membership estimation combined with model error modelling technique is used where the approach is based on worst case scenario with unknown but bounded uncertainties. The outcome is a robust identified model which consists of a nominal model with its uncertainty bounds that fits exactly the H∞ robust control scheme which has been utilized in active noise control in recent years. While the nominal model has the desired physical characteristics as cut-off frequency and the anticipated slope and flatness before and after this frequency, respectively, it is maintained in the acceptably tight uncertainty upper and lower limits, thus validating the identification procedure. Looseness and tightness of uncertainty strip has also been discussed regarding nonlinearities and measurement noise in low and high frequency regions. Meanwhile the identified nominal model can also be utilized in non-robust noise control methods due to its lower order, reflecting the advantage of the applied identification approach.

In this study, free vibration of a FOAM-core orthotropic SMART composite cylindrical shell (SCCS) filled with a non-viscous compressible fluid, subjected to combined electro-thermo-mechanical loads is investigated. Piezoelectric polymeric cylindrical shell, is made from polyvinylidene fluoride (PVDF) and reinforced by armchair double walled boron nitride nanotubes (DWBNNTs). Characteristics of the equivalent composite are determined using micro-electro-mechanical models. The poly ethylene (PE) FOAM-core is modeled based on Winkler and Pasternak foundations. Employing the charge equation for coupling electrical and mechanical fields, the problem is turned into an eigenvalue one, for which analytical frequency equations are derived considering free electrical and simply supported mechanical boundary conditions at circular surfaces at either ends of the cylindrical shell. The influence of electric potential generated, filled-fluid, orientation angle of DWBNNTs, FOAM-core and a few other parameters on the resonance frequency of SCCS are investigated. Results show that SCCS and consequently the generated Φ improve sensor and actuator applications in several process industries, because it not only increases the vibration frequency, but also extends economic viability of the SMART structure.

The aim of this study is to provide a method of making ultralight open cell copper FOAM with high surface area using chemical procedures. Among the various methods of making open-cell metal FOAMs, electrodeposition method is selected because it can be done in a clean way and is cheaper than other methods. In this method, an open cell polyurethane sponge was used as substrate. Then by choosing appropriate chemical solutions with specific technical knowledge, first polyurethane surface has activated and then by electroless-deposition method, polyurethane activated surface covered with a thin layer of copper. In the final stage, with the aid of electrodeposition the thickness of copper layer was increased to the desired thickness with a minimum required strength. The results show that electrodeposition can increase the thickness of copper layer from 3-5 microns that is obtained in electroless-deposition method to above100 to 150 microns. SEM results show that the micro structure of the deposited layer is globular. By controlling the thickness of deposited copper in electroplating, the surface area of the copper FOAM can be increased. According to results optimum time for electroless-deposition is between 5 to 7 minutes and for electrodeposition is 1 hour. The open-cell copper FOAM that is produced in this research is ultralight and due to it high surface can transfer heat with high rates.

Background & objectives: File fracture is one of the main concerns in root canal therapy, which can affect endodontic treatment outcomes. The present study aimed to assess the fracture rate of the SMART Tract X3 as a new file system, in comparison with the commonly used rotary file system, during the preparation of simulated severely curved root canals. Methods: A total of  180 resin blocks with simulated severely curved canals were randomly assigned to three equal groups (n=60) including SMART Tract X3, ProTaper Universal and Neoniti. Each set of files was used for cleaning and shaping of five canals, in total, 12 sets of files were used to prepare 60 channels in each group. All files were prepared according to the manufacturer’s instructions. The number (%) of fractures, location, length and distance of fractured segments from the apex of the block were recorded. Results: Overall 60 files of SMART tractX3 and ProTaper universal (5 files in a set) and 36 files of the Neoniti (3 files in a set) were used. The fracture rate did not show a statistically significant difference in between-groups comparison. All fractures occurred at the apical third of the canal with the mean length of fractured segments and the distance of fractured segments from the apex of the block 2. 228±0. 216 mm and 0. 845±0. 186 mm, respectively. Conclusion: There was no significant statistical difference among SMART Tract X3, ProTaper Universal, and Neoniti files regarding the incidence of fracture during the preparation of five severely curved canals.

In this paper, a new method for extending and relaxing the noise-coupling (NC) technique is proposed to enhance the noise-shaping order without adding the number of integrators. The noise-shaping order of the introduced ∑∆ modulator whit applying a second-order noise-coupling technique is enhanced and its performance with optimizing the noise transfer function (NTF) zeros is improved. Also, by removing the analog adder at feedforward path and transferring it to a new feedback branch before the last integrator and adding second-order NC path can be decreased the input voltage swing to the quantizer. Thus, by improving the modulator resolution, power consumption can be reduced. Mathematical analyses and behavioural simulation results confirm the effectiveness of the new NC method. To examine its performance, a 2nd-order single loop ΣΔ modulator was designed. The new noise-coupling method is used to achieve the three-order noise shaping to increase the resolution with low complexity and low-power. The results show an outstanding improvement in signal-to-noise and distortion ratio (SNDR) compared to the conventional structure.

Abstract In the design and construction of structures, especially water structures, and contact with any problematic soils, many issues and problems may arise during construction or operation, eventually leading to local destruction or destruction of the structure. Iran is one of the countries that, due to its special arid and semi-arid climatic conditions as well as its geology, many types of problematic soils are found in it, so the existence of this category of soils has been the source of many destructions and damages caused in There have been all kinds of structures, especially water structures in the country. To achieve the goals of the present research, tests were conducted on the soils of the construction site of Ramhormoz canals in three sections to identify the mineral type and morphology of the tested samples and to investigate the effect of different additives on the mechanical properties of the soil samples. The results of the research show that there are changes in the paste limit for all related samples, the lowest value for the sample with 5% lime is an increase of 3.58 and the highest value for the sample with 7% cement is an increase of 9.65. The changes in internal friction angle for all samples show that the lowest value related to the sample with 7% cement is equal to 0.1% increase and the highest value related to the sample with 7% cement is equal to 24.9% increase. INTRODUCTION In the design and construction of structures, especially water structures, and contact with any problematic soils, many issues and problems may arise during construction or operation, eventually leading to local destruction or destruction of the structure. Iran is one of the countries that, due to its special arid and semi-arid climatic conditions as well as its geology, many types of problematic soils are found in it, so the existence of this category of soils has been the source of many destructions and damages caused in There have been all kinds of structures, especially water structures in the country. METHOD AND MATERIAL To achieve the objectives of the present research, field sampling was done after studying the previous research, and then relevant laboratory studies were carried out by transferring the prepared samples to the laboratory. Laboratory studies of the current research in three sections: mineralogy of samples with XRD device, morphology of samples with SEM device; and Granulation of the samples was done by LPSA method. For sampling for the present research, data collection was done from the Ramhormoz region located in Khuzestan province, which has chalk soils and is the place where various water transfer structures are implemented. In this research, manual boreholes were dug from a depth of -30 (minus 30 cm) from the base level to a depth of -60 (minus 60 cm) and the information about the state of the soil layer was obtained by sampling the mentioned boreholes by performing the necessary tests. From the soil composition that was sampled from the mentioned places with 3 types of solid materials including: a- The combination of soil with type 2 cement with a combination of 2, 5%, and 7% by volume. b- Mixing the soil with slaked lime with a combination of 5% and 7% by volume. C - Mixing the soil with slag with 3 with a combination of 5% and 7% by volume. Results The results of this research show that the changes in the paste limit for all the samples show that the lowest value for the sample with 5% lime is a 3.58% increase and the highest value for the sample with 8% cement is a 9.65% increase. Also, the changes in the dry density of compaction show that the lowest value of the sample with 7% cement is equal to a 22% decrease and the highest value of the sample with 7% slag is equal to a 6% increase. The changes in adhesion coefficient show that the lowest value of the sample with 5% cement is a 15.4% decrease and the highest value of the sample with 5% slag is a 450% increase. The changes in the internal friction angle show that the lowest value corresponding to the sample with 5% and 7% lime, 5% and 7% slag, and the highest value corresponding to the sample with 5% cement is equal to a 5.8% increase. DISCUSSION AND CONCLUSION In general, the most important reactions of lime with soil can be divided into four categories: a) flocculation, b) carbonation, 3) ion exchange, and d) pozzolanic reactions, and each of these changes can be Even in a short period observed in the soil. In the event of any of the presented reactions, changes can be observed in the optimum moisture content, specific weight, reduction in plasticity indices, and increase in unconfined compressive strength. The mixture of lime and clay with the cation exchange reaction of clay minerals and as a result, coagulation of its fine particles, provides suitable conditions by which the flocculated clay particles together cause the formation of larger particles. This process involves the hydration reaction of quicklime. After this initial rapid reaction, more permanent reactions begin, such as the pozzolanic reaction in which materials impregnated with cement are used, the best performance of the samples is expected in a longer time. Hydration reactions are effective at temperatures above 20 degrees Celsius, at higher stages this reaction causes an increase in resistance through the formation of hydrated calcium silicate and hydrated calcium aluminate silicate from hydration and pozzolanic reactions. The formation of these compounds increases resistance.   Considering that the soil of the study area is gypsum, therefore, among the mechanical parameters of the soil, the coefficient of adhesion can be considered as the most important parameter. Therefore, based on the above explanation and based on the results obtained, mineral slag is added to the soil of the study area. It can be a suitable solution to solve the mentioned soil problem. ACKNOWLEDGEMENT The authors of the article express their gratitude to Khorramshahr University of Marine Sciences and Technology and Khuzestan Water and Power Organization for their financial and spiritual support of this research.