Influence of reflected waves at the bonded boundary in double-layered thickness-shear resonator using α-quartz

The influence of the reflected waves at the bonding boundary on the resonance waveform and temperature characteristics was investigated using α-quartz (QZ). The double-layered resonator specimen was fabricated using 129.55°Y- and 0°Y-cut QZ substrates with the thickness ratio x=0.520. The temperature characteristic at the range from 100°C to 300°C was deviated from the calculated values estimated by the equations considering thickness and electric flux density ratio proposed in the previous work, and the resonant waveform of the specimen was deteriorated as compared with that of single-layer resonators. In order to clarify these phenomena, the phase matching conditions and total amplitude in the specimen were examined. As a result, it was clarified that increase of the amplitude in the layer with lower acoustic impedance was affected to the temperature characteristic, and acoustic losses due to reflection / transmission at the bonding boundary was affected to the total amplitude of resonance.

Monopoles of the Dirac type and color confinement in QCD

We present results of SU(3) Monte-Carlo studies of a new color confinement scheme proposed recently due to Abelian-like monopoles of the Dirac type corresponding in the continuum limit to violation of the non-Abelian Bianchi identities (VNABI). The simulations are done without any additional gauge-fixing smoothing the vacuum. We get for the first time, in pure SU(3) simulations, (1) the perfect Abelian dominance with respect to the static potentials on (12 ~ 16)4 at β = 5.6 − 5.8 using the multilevel method, (2) the monopole as well as Abelian dominances with respect to the static potentials by evaluating the Polyakov-loop correlators on 243 × 4 at β = 5.6. The Abelian photon part gives zero string tension. The new SU(3) as well as the previous SU(2) results are consistent with the new Abelian picture of color confinement that each one of eight colored electric flux is squeezed by the corresponding colored Abelian-like monopole of the Dirac type corresponding to VNABI.

Liquid-Crystal-Based Floating-Electrode-Free Coplanar Waveguide Phase Shifter with an Additional Liquid-Crystal Layer for 28-GHz Applications

A liquid-crystal (LC)-based floating electrode-free (FE-free) coplanar waveguide (CPW) phase shifter with an additional LC layer is demonstrated for the first time. An LC layer is overlain on the electrodes of the original model; this change increases the amount of electric flux that the proposed structure can confine in the tunable region, and thereby greatly increases the figure-of-merit (FoM) while maintaining the benefits of the simple coplanar structure. We simulated the variations in the phase shifter’s FoM, characteristic impedance, and driving voltage while sweeping the additional LC layer thickness up to 300 μm with each electrode condition at 28 GHz. In the case of electrode thickness variation, the FoM increased as electrode thickness increased, regardless of the presence of the additional LC layer. However, in the case of the signal electrode width variation, we obtained an opposite FoM tendency depending on the presence of the additional LC layer. This work shows the possibility of an efficient LC-based FE-free CPW phase shifter design for a given LC layer and electrode conditions.

Effects of HPMC on Workability and Mechanical Properties of Concrete Using Iron Tailings as Aggregates

Iron ore tailings (IOTs) are gradually used as building materials to solve the severe ecological and environmental problems caused by their massive accumulation. However, the bulk density of IOT as aggregate is too large, which seriously affects the concrete properties. Therefore, in this paper, the effect of hydroxypropyl methylcellulose (HPMC) on the workability, mechanical properties, and durability of concrete prepared from IOT recycled aggregate was studied. The action mechanism of HPMC on the workability and the mechanical properties of the IOT concrete was analyzed by mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM). The results show that HPMC can effectively improve the segregation problem caused by the sinking and air entrainment of IOT aggregate and improve the crack resistance of concrete with little effect on its compressive strength and electric flux. These results are due to the air-entraining thickening effect of HPMC, which improves the slurry viscosity, hinders the sinking of aggregate, and improves the workability. At the same time, HPMC film, after concrete hardening, will bridge the slurry and aggregate through physical and chemical effects, hinder the propagation of microcracks, and improve the crack resistance.

Research on Interlayer Bonding Quality Control Method of Dam Concrete Based on Equivalent Age

Interlayer bonding quality is the key to the stability and durability of dam concrete. In this study, interlayer splitting tensile strength, relative permeability coefficient, and electric flux of dam concrete at different temperatures were tested. The relationships between equivalent age and strength coefficient, relative permeability coefficient ratio, and electric flux ratio were established. Meanwhile, a comprehensive early-warning and control system of dam interlayer bonding quality based on the above relationships was proposed. The results showed that the interlayer mechanical properties, impermeability, and anti-chloride ion permeability of dam concrete decreased with the increase of temperature. Moreover, the equivalent age was linearly correlated with strength coefficient, relative permeability coefficient ratio, and electric flux ratio of concrete. The correlation coefficients were 0.986, 0.973, and 0.924, respectively. In addition, the interlayer bonding quality of dam concrete can be effectively controlled by the early-warning system established according to the relationship between equivalent age and interlayer properties parameters.

Operator lifetime and the force-free electrodynamic limit of magnetised holographic plasma

Using the framework of higher-form global symmetries, we examine the regime of validity of force-free electrodynamics by evaluating the lifetime of the electric field operator, which is non-conserved due to screening effects. We focus on a holographic model which has the same global symmetry as that of low energy plasma and obtain the lifetime of (non-conserved) electric flux in a strong magnetic field regime. The lifetime is inversely correlated to the magnetic field strength and thus suppressed in the strong field regime.

Investigation on Electrical Resistance of Chloride Penetration of Alkali Activated Slag Concrete

Alternating-current method for measuring chloride penetration resistance of concrete, test method for coulomb electric flux and rapid chloride migration coefficient (RCM) were applied to evaluate the resistance of chloride penetration in alkali-activated slag concrete in this paper. At the same time, the applicability of the above three electrical parameters test methods to the alkali slag concrete was discussed. The results show that NaOH activated slag concrete behaves higher resistance to chloride penetration than water glass activated slag concrete. Blend of fly ash increases the porosity of alkali-activated slag concrete and weakens the resistance of chloride penetration. Correlation coefficient between chloride migration coefficient and AC electrical resistivity is 0.99. There are good correlations among the evaluation results of three electrical parameters test methods, and all of them behave sound applicability to alkali-activated slag concrete.

Application of Advanced Composite Cementitious Materials and High Performance Admixtures in High Performance Shotcrete

In this paper, the influence of liquid alkali-free accelerator and advanced composite cementitious materials on the mechanical properties, durability and workability of shotcrete was studied. The important role of the two materials in the performance improvement of shotcrete was clarified. The technical measures proposed were verified by field test. The results show that: In terms of workability, the composite use of alkali-free accelerator and functional admixture can achieve fast setting and high early strength of shotcrete, thus effectively reducing the rebound rate; In terms of mechanical properties, functional admixture can effectively improve the early mechanical properties of shotcrete, while alkali-free accelerator can ensure the long-term development of mechanical properties; In terms of durability, the use of functional admixtures can effectively improve the compactness of shotcrete, and the test results of 56d electric flux are lower than 1000C.