First-principles insight into two-dimensional palladium phosphide tellurium (PdPTe) monolayer as a promising scavenger for detecting SF6 decompositions

Journal of Materials Science - Recently, the monitoring of SF6 decomposition components has allured notable attention. SF6 decomposition products are toxic and corrosive, which will greatly reduce...     

A New Three-mode Maximum Power Point Tracking Algorithm for Doubly Fed Induction Generator Based Wind Energy Conversion System

This paper proposes a new algorithm for maximum power point tracking of a wind energy conversion system, which is based on a doubly fed induction generator. The algorithm has three modes. In the first mode, the maximum power point is tracked and also the output power is smoothed. Once the turbine operating point reaches the optimal point, the second mode is activated to fix the speed of the turbine. In addition, this mode has a self-tuning capability. When the turbine operating point is far from the optimal value, the third mode is activated. In this mode, the optimal power curve along with the fuzzy logic is used to bring the turbine operating point rapidly to a point near the maximum power point. To verify the accuracy of the proposed algorithm, a large wind energy conversion system is simulated, and the simulation results are compared with the perturbation and observation algorithm.     

Statistical Modeling of Zr/Hf Extraction using TBP–D2EHPA Mixtures

In the present work, response surface methodology was employed for the study and prediction of Zr/Hf extraction curves in a solvent extraction system using D2EHPA-TBP mixtures. The effect of change in the levels of temperature, nitric acid concentration, and TBP/D2EHPA ratio (T/D) on the Zr/Hf extraction/separation was studied by the use of central composite design. The results showed a statistically significant effect of T/D, nitric acid concentration, and temperature on the extraction percentage of Zr and Hf. In the case of Zr, a statistically significant interaction was found between T/D and nitric acid, whereas for Hf, both interactive terms between temperature and T/D and nitric acid were significant. Additionally, the extraction curves were profitably predicted applying the developed statistical regression equations; this approach is faster and more economical compared with experimentally obtained curves.     

Detection of Winding Radial Deformation in Power Transformers by Confocal Microwave Imaging

In this article, a new bi-static method for the detection and determination of magnitude and location of winding radial deformation in power transformers has been proposed. In this method, which is based on confocal microwave imaging, a ultra-wideband transceiver is utilized to emit a short pulse toward the transformer winding and determine its reflection at several points along a linear path. The measured signals are then processed to obtain a 2D image of the winding. The effectiveness of this algorithm for radial deformation is demonstrated through four different experiments. The resultant image provides satisfactory information of the magnitude and position of the radial deformation in transformer.     

Remote‐controlled peristaltic locomotion in free‐floating pnipam hydrogels

Peristalsis‐driven locomotion, by nature of its flexibility and deformability, is a highly advantageous mechanism for mobility in soft materials and robots; however, utilization of this mechanism has been limited to restricted, frictional environments. (Seok et al., presented at 2010 IEEE International Conference on Robotics and Automation, Anchorage, AK May 3–8, 2010; Boxerbaum et al., Int J Robotics Res 2012, 31, 302; Boxerbaum et al., presented at 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, San Francisco, CA, 2011; Arora et al., J Polym Sci Part A: Polym Chem 2009, 47, 5027). We have removed this limitation and expanded the use of peristaltic locomotion to open aqueous environments by remotely inducing peristalsis via spatially controlled volume phase transitions in thermosensitive poly(N‐isopropylacrylamide) (PNIPAM) hydrogels. The resulting asymmetry causes steady, incremental linear displacement in the hydrogel's center of mass, thus producing directed, remote‐controlled locomotion. In our proof‐of‐principle system, we controlled the peristaltic locomotion of the hydrogels using a handheld laser to selectively induce volume phase transitions in the hydrogel. The PNIPAM hydrogels' energy absorbance capability was enhanced by incorporating the New Indocyanine Green laser dye (IR‐820) into the gel. The use of IR‐820 is likely to expand the application space for these hydrogels due to new opportunities for conjugation chemistry. (Prajapati et al., Molecular Imaging 2009, 8, 45; Fernandez‐Fernandez et al., Molecular Imaging 2011, 11, 1). Overall, such an approach increases the capability of both peristaltic locomotion as a mechanism for mobility in soft robots, and PNIPAM hydrogels as a biotechnological platform. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40927.     

Evaluation of site response characteristic using nonlinear method (Case study: Babol,Iran)

In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data and synthesis of drilling data extracted from the Babol’s subsurface database have enabled authors to determine the geotechnical properties of each site. These data are consisted of twenty five boreholes up to depth of 40 m. Based on the obtained data from geotechnical investigation the study area is divided to five zones. Dynamic analysis was performed in time domain, using fully nonlinear model by PLAXIS. A series of analysis in the study area showed the site period, ranging from 0.4 to 0.8 s. Finally the obtained response spectra from fully nonlinear method were compared with site response spectra of Iran’s 2800 (earthquake) code.     

Structural and free volume characterization of sol–gel organic–inorganic hybrids,obtained by co-condensation of two ureasilicate stoichiometric precursors

In this study two hybrid organic–inorganic ureasilicate monomers with different length of polymer segments were chosen for preparation of sol–gel material that includes two moieties blended on the molecular scale. The first monomer was obtained by crosslinking a double terminated polyoxyalkyleneamine with an isocyanate modified silicone ethoxide and the second one – by crosslinking between the isocyanate modified silicone ethoxide with an amino modified silicone ethoxide. Sol–gel route was applied for transformation of the liquid monomer blends in transparent materials with varying degree of rigidity. The prepared samples were characterized by small-angle X-ray scattering, Fourier-transform infrared spectroscopy, positron annihilation lifetime spectroscopy, and swelling experiments. The results demonstrate that the structure of the obtained materials could be tuned by a simple variation of molar fraction ratio between these two monomers. This makes it possible to obtain nanostructured materials with predictable properties.     

Dominant role of drivers’ attitude in prevention of road traffic crashes: A study on knowledge,attitude, and practice of drivers in Iran

Objective

Evaluating the relation between Iranian drivers’ knowledge, attitude, and practice (KAP) regarding traffic regulations, and their deterministic effect on road traffic crashes (RTCs).

Setting

Two cities of Tehran and Zahedan, Iran.

Methods

A cross-sectional study was designed. Using a simplified cluster sampling design, 2200 motor vehicle drivers including 1200 in Tehran and 1000 in Zahedan were selected. Sixty locations in Tehran and 50 in Zahedan were chosen. In each pre-identified location, 20 adult drivers were approached consecutively. A questionnaire developed by researchers was filled by each participant. The questionnaire had four sections including items assessing the demographics, knowledge, attitude and practice of drivers toward traffic regulations. Logistic regression analysis was used to evaluate the relationship between the RTCs and KAP variables.

Results

The study sample consisted of 619 (28.1%) occupational and 1580 (71.8%) private drivers. Among them, 86.4% were male. The median age was 33.6 ± 10.83. Drivers in Tehran and Zahedan had no significant differences between their mean scores of KAP items of the questionnaire. Higher knowledge, safer attitude, and safer practice were associated with a decreased number of RTC. After adjusting for possible confounders, increase of one standard deviation in attitude and practice scores (but not knowledge) resulted in 26.4% and 18.5% decrease in RTC, respectively. Finally, considering knowledge, attitude and practice of drivers in one model to assess their mutual effect, it was shown that only attitude is significantly associated with a decrease of RTC (OR = 0.76, P = 0.007).

Conclusion

Increase in attitude and practice accompanied with decreased number of RTCs in Iranian drivers. Specifically, drivers’ attitude had the crucial effect. It is not knowledge and standard traffic education; rather it is how such education is registered as an attitude that translates what is being learned into actions. Without safer attitude, even safer self-reported practice will not result in lower RTCs.     

A new frequency compensation technique for three stages OTA by differential feedback path

A new single Miller capacitor for frequency compensation of three‐stage amplifier is proposed in this paper. In this scheme, a differential stage in which its negative and positive inputs are connected to the output and input nodes of third stage with a cascade capacitor forms the compensation block of a conventional three‐stage amplifier. Analysis shows that this configuration significantly improves the frequency domain performances of total circuit such as phase margin (PM) and gain‐bandwidth product (GBW) with just a very small amount of compensation capacitor. A three‐stage amplifier has been simulated with and without a differential feedback path in a 0.18 µm complementary metal–oxide–semiconductor (CMOS). The simulated amplifier with a 100 pF capacitive load achieved more than 9 MHz GBW and 83° PM while the compensation is less than 0.2% of load capacitor. An amplifier based on conventional nested Miller compensation can just achieve less than 0.23 MHz GBW with the same load, while using more than 100 pF as compensation capacitor. So this method shows an improvement of a factor of 40 in GBW and reduction of a factor of 550 in the size of compensation capacitor. It is a suitable strategy for ON‐CHIP compensation in comparison to other methods. Copyright © 2014 John Wiley & Sons, Ltd.