Photonic Stopband Filters Based on Graphene-Pair Arrays

We investigate the photonic bandgaps in graphene-pair arrays. Graphene sheets are installed in a bulk substrate to form periodical graphene photonic crystal. The compound system approves a photonic band structure as a light impinges on it. Multiple stopbands are induced by changing the incident frequency of light. The stopbands widths and their central frequencies could be modulated through the graphene chemical potential. The number of stopbands decreases with the increase in the spatial period of graphene pairs. Otherwise, two full passbands are realized in the parameter space composed of the incident angle and the light frequency. This investigation has potentials applied in tunable multi-stopbands filters.

Scattering of Antiplane SH Waves by Complex Landforms

The multiple scattering of SH waves by isosceles triangular hill, semicircle depression, and isosceles trapezoidal hill in the solid half-space is studied. The complex model is divided into multiple subdomains by using the region matching method, then the wave functions in each subdomain are constructed by using the fractional-order Bessel function, and finally, the infinite algebraic equations for solving the unknown coefficients in the wave function are established by using the multipolar coordinate technique and the complex function method according to the boundary conditions. Fourier series is used to solve the unknown undetermined coefficients. The results show that due to the multiple reflections of the incident wave between complex landforms, surface displacement amplitude is affected by the incident angle, incident frequency, and the distance between the isosceles triangular hill, semicircle depression, and isosceles trapezoidal hill. It is found that when the incident frequency increases, there is a certain amplification effect between the hills and the depression. When the wave is incident horizontally, there is a certain “barrier” effect between hills and depression, and when the distance between the hills and depression reaches a certain level, the “barrier” effect will reach a stable value.

Comparison of Fatigue, Quality of Life, Turnover Intention, and Safety Incident Frequency between 2-Shift and 3-Shift Korean Nurses

This study aimed to compare the fatigue, quality of life, turnover intention, and safety incident frequency between 2- and 3-shift nurses, and analyze their perceptions of the 2-shift system. Participants were 227 nurses working for one year or more in a tertiary hospital in Seoul, South Korea (113 were 2-shift nurses for two months or longer, and 114 were 3-shift nurses with no experience of 2-shift work). The Occupational Fatigue Exhaustion Recovery Scale (OFER) and Quality of Life Scale were used. Turnover intention, safety incident frequency, and perceptions of the 2-shift system were surveyed by questionnaires developed by the researchers. Results showed that 2-shift nurses had lower chronic fatigue (t = −2.38, p = 0.018) and higher recovery between shifts (t = 3.90, p < 0.001) and quality of life scores than 3-shift nurses (t = 3.69, p < 0.001). There were no significant differences for turnover intention (t = −1.48, p = 0.140), frequency of needlestick accidents (t = 0.30, p = 0.763), medication errors (t = −1.46, p = 0.146), or near-miss medication errors (t = 0.78, p = 0.437). Two-shift nurses found it easier to secure rest and personal leisure time, and their shift system was shown to improve work satisfaction by increasing the continuity of care. Additional research is necessary to examine how nurses’ health status and emotional satisfaction vary by shift type.

Application of a Hurdle Model with Random Effects to Explore the Relationship between Operational Characteristics and Safety Performance

This study used the bus incident data in Victoria, Australia to establish the relationship between operational characteristics and the safety performance of bus operators. A series of count models were investigated to account for methodological challenges, including excess zeros and panel data structure. The empirical results highlighted the different effects operational characteristics had on the risk and prevalence of bus incidents. Operators of smaller size, providing non-route services and operating in regional areas had a lower risk of having any reported incidents compared with larger route operators and operators in areas of higher accessibility. In cases where at least one incident had been reported, incident frequency was higher for operators with higher fleet total travel distance, older fleets and better roadworthy performance (this factor being counterintuitive). Findings from this study provide safety regulators with evidence-driven opportunities to enhance bus safety, including improving incident reporting practices, the establishment of a comprehensive database for heavy vehicle operators, and specific efforts targeted at older fleets.

Optical bistability in two-dimensional nonlinear composites of coated cylinders with nonlinear core and graded shell

The intrinsic optical bistability of the nonlinear composite consisting of coated cylinders with nonlinear core and graded Drude shell is investigated with self-consistent mean-field approximation. We derive the nonlinear equation of near field for such graded composite in the quasistatic limit. We demonstrate that the bistability threshold and the bistable width are highly dependent on the core radius, the incident frequency, and the graded coefficient of the coated cylinder inclusion. It is found that the optical bistability appears only when the core radius and the incident frequency satisfy some specific conditions. Therefore, the optical bistability for nonlinear composite materials may be optimized by the suitable adjustment of the physical and geometrical parameters. Our results may be helpful for the design of the nonlinear device with appropriate bistability.

Synthesis and Characterization of Structural, and Electrical Properties of Mg(0.25x)Cu(0.25x)Zn(1 – 5x)Fe2O4 Ferrites by Sol-Gel Method

The effects of magnesium, copper, and zinc substitutions on spinel ferrites have been investigated by the sol-gel technique. Ferrite compositions of Mg0,25xCu0,25xZn(1−0,5x)Fe2O4 (where x = 0.6, 0.7, 0.8 & 0.9) were prepared at a sintering temperature of 1100 ∘C with a presintering at 500 ∘C. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-precision impedance analysis are used to characterize structural and dielectric properties, as well as the surface topography and morphology of the samples. A single phase, cubic spinel structure, with decreased lattice constant was observed. SEM micrographs revealed a homogeneous microstructure with uniform size distributions. Both the dielectric constant and dielectric loss tangent decrease, as the incident frequency increases up to a certain saturation point. The direct current (dc) resistivity profile shows that the resistivity increases with the temperature up to the Curie point, then it goes to a constant value. The quality factor (Q-factor) increases with the incident frequency. Hence, the high Q-factor will make ferrites highly useful in applications, especially in multilayer chip inductors.

High-Resolution Ultrasonic Inspection Images of Semiconductor Packages by Advanced High-Frequency Transducers

This paper describes a method for obtaining high-resolution ultrasonic inspection images of semiconductor packages. We evaluated the effect of the incident ultrasonic frequency on the resolution and defect detection. When the incident frequency of the ultrasonic transducers is changed from 300 MHz to 400 MHz, the capability to detect package defect improves from 2.5 µm to 1.0 µm. The observed images of semiconductor packages proves that a 400 MHz transducer can be applied to inspect sophisticated LSIs.

Freeway Incident Frequency Analysis Based on CART Method

Classification and Regression Tree (CART), one of the most widely applied data mining techniques, is based on the classification and regression model produced by binary tree structure. Based on CART method, this paper establishes the relationship between freeway incident frequency and roadway characteristics, traffic variables and environmental factors. The results of CART method indicate that the impact of influencing factors (weather, weekday/weekend, traffic flow and roadway characteristics) of incident frequency is not consistent for different incident types during different time periods. By comparing with Negative Binomial Regression model, CART method is demonstrated to be a good alternative method for analyzing incident frequency. Then the discussion about the relationship between incident frequency and influencing factors is provided, and the future research orientation is pointed out.

Intensity Variation of the Electromagnetic Emission (EME) of Rock Masses Failure under Dynamic Load

Incident frequency of wave on the intensity variation of the EME had been studied in this paper, based on failure test under dynamic load of Granite. The results show that the intensity of EME gradually attenuates with increasing of incident frequency of wave. The intensity of EME with the joint stiffness; the intensity of EME increases with viscosity coefficient; the variation of the EME with viscosity coefficient is influenced by frequency. The research outcomes are in agreement with others experimental results.