Chiral tunneling in trilayer graphene

We study the effect of chiral-tunneling in Bernal and Rombhohedral stacked trilayer-graphene (3LG). Based on the chirality of the electronic bands, at the K-point, (Rombhohedral) Bernal-3LG exhibits 100% (50%) transparency across a heterojunction. Utilizing this property, we further investigate the effect of electron collimation in 3LG. Due to the difference in the Berry's phase, we show that, Rombhohedral-3LG is a better electron collimator, compared to monolayer and Bernal-bilayer graphene. Since, Bernal-3LG can be decomposed into two separate channels consisting of a monolayer and a modified Bernal-bilayer graphene; the Bernal-3LG is weaker electron collimator, compared to Rombhohedral-3LG.Comment: APL, 2012; http://dx.doi.org/10.1063/1.370375

Transversal electric field effect in multilayer graphene nanoribbon

We study the effect of transversal electric-field (E-field) on the electronic properties of multilayer armchair-graphene-nanoribbon (AGNR). The bandgap in multilayer-AGNRs can be reversibly modulated with the application of E-field. At optimized widths, we obtain a semiconductor (SC) to metallic (M), as well as M-SC transition. The AGNR electronic bands undergo vivid transformations due to the E-field, leading to phenomena such as increase in electron velocity, change in the sign of the electron effective mass, and the formation of linear dispersion with massless Dirac fermions similar to 2D-graphene. These effects are very useful and can be utilized for device applications.Comment: 8pages, 3 fi

Theoretical Implementation of All-Optical XOR Gate at 160 Gb/s Using Semiconductor Optical Amplifiers-Based Turbo-Switched Mach-Zehnder Interferometer

The implantation of an all-optical eXclusive-OR (XOR) gate run at 160 Gb/s using semiconductor optical amplifiers (SOAs)-based turbo-switched Mach-Zehnder interferometer (TS-MZI) is theoretically investigated and verified. The dependence of the quality factor (QF) on the signal and SOA key operating parameters is examined and assessed, including the impact of amplified spontaneous emission in order to obtain realistic results. A higher QF is obtained when using SOAs-based TS-MZI than when using conventional SOAs-based MZI

Wind speed modeled as an indexed semi-Markov process

The increasing interest in renewable energy, particularly in wind, has given rise to the necessity of accurate models for the generation of good synthetic wind speed data. Markov chains are often used with this purpose but better models are needed to reproduce the statistical properties of wind speed data. In a previous paper we showed that semi-Markov processes are more appropriate for this purpose but to reach an accurate reproduction of real data features high order model should be used. In this work we introduce an indexed semi-Markov process that is able to fit real data. We downloaded a database, freely available from the web, in which are included wind speed data taken from L.S.I. -Lastem station (Italy) and sampled every 10 minutes. We then generate synthetic time series for wind speed by means of Monte Carlo simulations. The time lagged autocorrelation is then used to compare statistical properties of the proposed model with those of real data and also with a synthetic time series generated though a simple semi-Markov process.Comment: arXiv admin note: substantial text overlap with arXiv:1109.425

Determination of statistical homogeneity by comprehensively considering the discontinuity information

Statistička homogenost stijenske mase oduvijek je važno pitanje u inženjerstvu stijenske mase. U ovom je radu analizirana stijenska masa podzemnog skladišta nafte na otoku Huang usmjerena na raspodjelu statistički homogenog područja. Duljina rasprostiranja je osnovni element za određivanje karakteristika pukotina. Stijenska masa različitih duljina rasprostiranja pukotina uvelike se razlikuje kad se radi o mehaničkim i karakteristikama deformacije. Ovaj rad obuhvaća podatke o duljini rasprostiranja u podjeli statistički homogenog područja i razmatra vrijednosti varijance i srednje vrijednosti uzoraka pukotina odvojeno u različitim područjima F-testom i T-testom kako bi se utvrdilo imaju li uzorci statistički slične podatke o duljini rasprostiranja. Potrebni su brojni uzorci pukotina da bi se dobilo statistički homogeno područje. U ovom je radu primijenjen Watsonov test za određivanje statistički homogenog područja i razmatrani su podaci o pojavi pukotina u svrhu dobivanja manjeg broja uzoraka za usporedbu pojave pukotina. Podaci o postojanju pukotina i duljini rasprostiranja analiziraju se uvođenjem F-testa, T-testa i Watson-testa kako bi se dobili osnovni podaci o pukotinama i objektivni i prihvatljivi rezultati za statističku homogenost.The statistical homogeneity of rock mass has always been an important issue in rock mass engineering. The rock mass of national underground oil storage in Huang Island is analyzed in this study with focus on the division of a statistically homogeneous area. Trace length is a basic element in determining crack features. The rock mass of different track lengths differs widely in terms of mechanics and deformation characteristics. This study includes trace length information in the division of a statistically homogeneous area and considers the variances and mean values of crack samples in different regions separately by F-test and T-test to determine if the samples have statistically similar trace length information. Numerous crack samples are required to divide a statistically homogeneous area. This study adopts the Watson test to divide a statistically homogeneous area and considers data on crack occurrence to achieve the purpose of obtaining fewer samples for occurrence comparison. Crack occurrence and trace length information are considered by integrating F-test, T-test, and Watson test to gather adequate basic information on cracks and obtain objective and reasonable results for statistical homogeneity

Long-chain polyunsaturated fatty acid metabolism in carnivorous marine teleosts: insight into the profile of endogenous biosynthesis in golden pompano Trachinotus ovatus

Golden pompano Trachinotus ovatus is an important farmed carnivorous marine teleost. Although some enzymes for long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis have been identified, the ability of T. ovatus for endogenous biosynthesis is unknown. Here, we evaluated in vivo LC-PUFA synthesis in a 56-day culture experiment using six diets (D1-D6) formulated with linseed and soybean oils to produce dietary linolenic/linoleic acid (ALA/LA) ratios ranging from 0.14 to 2.20. The control diet (D0) used fish oil as lipid source. The results showed that, compared with the corresponding indeces of fish fed D0, the weight gain rate and specific growth rate, as well as the contents of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in tissues (liver, muscle, brain and eye) of D1-D6 groups were significantly lower (P < 0.05). These data suggested that T. ovatus could not synthesize LC-PUFA from C18 PUFA or such ability was very low. However, tissue levels of 20:4n-3 in fish fed diets D1-D6 were higher than that of D0 fish (P < 0.05), and positively correlated with dietary ALA/LA ratio, while levels of EPA showed no difference among the D1-D6 groups. These results indicated that Δ5 desaturation, required for the conversion of 20:4n-3 to EPA, may be lacking or very low, suggesting incomplete LC-PUFA biosynthesis ability in T. ovatus

Fine control of Curie temperature of magnetocaloric alloys La(Fe,Co,Si)13 using electrolytic hydriding

This work demonstrates precision control of hydrogen content in La(Fe,Co,Si)13Hδ for the development of environmentally friendly magnetocaloric-based cooling technologies, using an electrolytic hydriding technique. We show the Curie temperature, a critical parameter which directly governs the temperature window of effective cooling, can be varied easily and reproducibly in 1 K steps within the range 274 K to 402 K. Importantly, both partially (up to 10%) and fully hydrided compositions retain favorable entropy change values comparable to that of the base composition. Crucially, we show in these second-order phase transition compounds, partial hydriding is stable and not susceptible against phase separation