An ultrathin acoustic metasurface composed of an anisotropic three-component resonator

An ultrathin acoustic metasurface consisting of an anisotropic three-component resonator is proposed. The resonator can induce nondegenerate dipole resonances at the same resonant frequencies. A large phase delay can be obtained based on the resonance, which can be modulated by the direction of polarization. The anisotropic resonator can be regarded as an effective homogenous medium with an anisotropic mass density, and the phase change can also be attributed to the change of the effective material parameters. A good comparison between the results for the metasurface and its effective slab is obtained.

Periodicities in the time-series of the annual mean temperatures of Central England

ABSTRACT .Maximum Entropy spectral Analysis (MESA) of the 8IUlua1 mean temperature series for Central England for 1659-1991 indicated significant periodicilies at T = 7.8, 11.1, 12.5, 15, 18, 23, 32, 37, 68, 81, l09 and 203 years. These compare well with T = 22, 30, 80, 200 years obtained for China. Also, a good comparison is obtained with some periodicities in the sunspot number series.

Application of Linear Free Energy Relationships (LFER) to pKaH+ of Benzimidazolium Cations: Chemical Education Perspective

Application of Linear Free Energy Relationships (LFER) to pKaH+ data in water at 25o C of deprotonation of protonated fused ring systems like benzimidazolium cations is carried out in the present work. With a good comparison of the sites of substituents with reference to a functional group in benzene ring and the imidazolium ring, an excellent Hammett correlation is observed for the deprotonation of (pKaH+) of protonated fused ring systems like benzimidazolium cations. For the three substituents OH, MeO and Me at position 4 in the benzimidazole satisfy the correlation with I values. A positive Hammet  values of 1.93 indicates that electron withdrawing substituents facilitate the deprotonation. Under the same conditions a Taft * value of 1.11 is obtained for the deprotonation of 2-substituted-benzimidazolium cations. The available pKaH+ data in 5% aq. ethanol at 30o C of 2-methyl benzimidazolium cations and 2-(hydroxyethyl) benzimidazolium cations also followed Hammett correlation. The lower Hammett  value of 0.89 for 2-(hydroxyethyl) benzimidazolium cation series than that of 1.78 of 2-methyl benzimidazolium cation series is explained in terms of strong intramolecular hydrogen bonding in 2-(hydroxyethyl) benzimidazolium cation which resists the easy deprotonation. Deprotonation of 1-substituted-benzimidazolium cations did not follow Hammett relation.

The effect of crumb rubber in dense graded and open graded cold mixture asphalt

Recycling tires is one of the eco-friendly way for reducing environmental problems. Incorporating crumb rubber in asphalt mixtures is an alternative way for reusing the end-of-life tires in road construction. The main purpose of this study is to evaluate the cold mix asphalt incorporating crumb rubber as a substitute for a part of fine aggregates. In this study, the aggregate gradations for mix design were selected according to the specification, Dense Graded Emulsion Mixtures (DGEM) Type IV and Open Graded Emulsion Mixtures (OGEM) Type E/20. The design bitumen content in this study was optimized for stability, void in mixture (porosity), and density. Crumb Rubber (CR) emulsion mixtures were made with optimum bitumen content at 8% by mass of total mixture for DGEM and OGEM. In order to incorporate crumb rubber into the cold emulsion mixtures, laboratory testing were performed for 25% and 50% of fine aggregates replaced with an equal volume of crumb rubber. In general, CR emulsion mixtures showed good results in all parameters. The CR emulsion mixtures also had a good comparison to hot mix asphalt specification for medium volume traffic loads with porosity less than 10%. From this study, crumb rubber can be recommended as a substitution material of fine aggregates in cold mix asphalt.

A variety of exact solutions of the (2+1)-dimensional modified Zakharov–Kuznetsov equation

From the point of view of two distinct methods, we will construct new multiple types of private exact solutions of the (2+1)-dimensional modified Zakharov–Kuznetsov equation (MZKE) which is a famous model in plasma physics. The suggested methods for this purpose are the extended simple equation method (ESEM) and the Paul–Painleve approach method (PPAM). Moreover, the numerical solutions corresponding to the achieved solutions are demonstrated in the framework of the variational iteration method (VIM). Furthermore, we will demonstrate a good comparison not only between our achieved solutions but also with that realized previously by other authors who studied this model before.

Comparing Measurements of Intracardiac Echocardiography and Other Periprocedural Imaging of the Left Atrial Appendage For Percutaneous Occlusion

Background: Intracardiac echocardiography (ICE) has recently been used as a safe and feasible imaging to guide left atrial appendage occlusion (LAAO). However, there is no good comparison of the correlation of left atrial appendage (LAA) measurements between ICE, transesophageal echocardiography (TEE), cardiac computed tomography angiography (CCTA) and fluoroscopy. Methods: We compared the correlation between ICE and CCTA, TEE, fluoroscopy on two key LAA measurements of each patient: (1) Lambre measured the landing zone and orifice; (2) Watchman measured the ostium and depth. Results: In this study, the success rate of operation was 100%, and no major adverse events occurred. For Lambre landing zone, mean measurements were 22.5±4.0mm with ICE, 23.5 ±4.5mm CCTA, 22.0±4.5mm TEE, 21.5±4.4mm fluoroscopy (P < 0.001). R values 0.78 ICE/CCTA, 0.85 ICE/TEE, 0.81 ICE / fluoroscopy; For Lambre orifice, mean measurements were 29.1±4.0mm with ICE, 31.0±3.9mm CCTA, 25.6±4.6mm TEE and 28.9±3.9mm fluoroscopy (P < 0.001). R values 0.68 ICE/CCTA, 0.76 ICE/TEE, and 0.75 ICE/fluoroscopy. For Watchman ostium, mean measurements were 22.7±3.2mm with ICE, 23.9±3.2mm CCTA, 21.9±3.1mm TEE, and 21.6±3.0mm fluoroscopy (P<0.001). R values 0.69 ICE/CCTA, 0.85 ICE/TEE, and 0.71 ICE/fluoroscopy; For Watchman depth, mean measurements were 22.1±3.1mm with ICE, 24.8±4.1mm CCTA, 23.7±2.9mm TEE, and 21.1±3.3mm fluoroscopy (P=0.002). R values 0.31 ICE/CCTA, 0.67 ICE/TEE, and 0.41 ICE/fluoroscopy. Conclusion: ICE from LA can be a safe and efficacious imaging option to guide LAAO, and ICE has good correlation with CCTA, TEE and fluoroscopy.

Creep Behavior of Intact Loess Followed Unloading Paths

Several high-fill projects are carried out on the Loess Plateau, China, accompanying the progressive failure of slopes due to excavation. The compelling need requires a deep understanding of variation in the creeping behaviors of intact loess exposed to unloading. A series of creep tests of intact loess were performed under two separated unloading paths: decrease in confining pressure at constant deviator stress and decrease in confining pressure at axial stress. The results demonstrated that axial deformation followed the first unloading path always appears as compression while the three forms of axial deformation followed the second path, depending on the applied axial stress level. At a low unloading stress level, the elongation of axial deformation was observed. At a relatively unloading stress level, the axial deformation of the soil experienced the first elongation and then compression. At a high unloading stress level, the axial deformation appeared as compression, and finally, failure occurred with the increase of the unloading stress level. The failure approach index was introduced to use as the criterion for the loess to transform from stable to accelerated creeping. Finally, a modified Burgers model was proposed to characterize the creeping behavior of intact loess followed unloading paths. There was a good comparison between the calculated and measured data of the soil that establishes the rationality and validity of the proposed model.

Reducing Furnace Operating Costs: IGBT/MFDC Technology Saves on Energy

Real power savings are observed in a case study comparing a VRT (Variable Reactance Transformer) and an IGBT/MFDC power supply in a furnace retrofit. The IGBT (Insulated Gate Bipolar Transistor) is the power controller and MFDC (Mid Frequency Direct Current) is the transformer portion of the power supply. The VRT was replaced with a similarly sized IGBT/MFDC power supply. Other variables remained essentially equivalent and provided a good comparison between the power consumption of a VRT versus an IGBT/MFDC system in an equivalent furnace. IGBT/MFDC offers cost savings through less kilowatt usage, lower peak demand, and better power factor when compared to other power controls. From this case study, we will demonstrate a 40 percent reduction in kilowatt consumption, a 14 percent reduction peak demand, and a high displacement power factor throughout the cycle. All of this results in lower costs for furnace operation.

Compact Tri-Band Microstrip Patch Antenna Using Complementary Split Ring Resonator Structure

In this letter, a compact complementary split ring based tri-band antenna is proposed. The proposed antenna resonates at 1.9 GHz (1.70-1.91 GHz), 2.45 GHz (2.23-2.52 GHz) and 3.2 GHz (2.9-3.25 GHz); the input match values are 24.56 dB, 27.21 dB and 22.46 dB, respectively. The antenna’s realised peak gain is 4.15 dBm at 1.9 GHz, 4.25 dBm at 2.4 GHz and 4.74 dBm at 3.2 GHz, with approximately 42% of reduction in antenna size. The results demonstrate that the proposed metamaterial antenna is tunable, electrically small and highly efficient, which makes it a suitable candidate for RF energy harvesting. The antenna is numerically and experimentally analysed and validated with very good comparison between the simulated and measured results.

Application of Ground based Microwave Radiometer in Aviation Weather Forecasting in Indian Air Force

Time and intensity specific very short-term forecasting or nowcasting is the biggest challenge faced by an Aviation Meteorologist. Ground-based Microwave Radiometer (MWR) has been used for nowcasting convective activity and it was established that there is a good comparison between thermodynamic parameters derived from MWR and GPS radiosonde observations, indicating that MWR observations can be used to develop techniques for nowcasting severe convective activity. In this study, efforts have been made to bring out the efficacy of MWR in nowcasting thunderstorms and fog. Firstly, the observations of MWR located at Palam, New Delhi, India have been compared with the nearest radiosonde (RS) data to ascertain the variation in respective profiles. Large differences were found in Relative Humidity (RH) whereas temperatures from MWR were found to be close to RS observed temperature upto 3.5 Km. Subsequently, the scattered plots and correlation coefficient of thermodynamic indices / parameters indicated that most of the parameters are either not correlated or have moderate correlation only for 1200 UTC profiles. The superepoch technique of lagged composite for various thermodynamic indices / parameters to obtain a combined picture of all the thunderstorm and dense fog cases on the time series could not determine any pattern to predict thunderstorm and dense fog with lead time of 2-4 hours. MWR profile for a case of occurrence of thunderstorm was analyzed. No significant variation was observed in most of the indices (as calculated from MWR observed parameters) prior to the occurrence of thunderstorm. RH at freezing level and between 950 and 700 hPa levels were the only parameters which increased four hours prior to the occurrence.