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A reactivity control method for accelerator-driven system (ADS) is studied for its ability to reduce both the maximum beam current and the load on the beam window. A burnable position (BP) assembly (with gadolinium and zirconium hydride pins) is applied to the ADS core for reactivity control, and various BP assembly optimizations (such as pin arrangement, BP assembly loading position, and BP composition) are performed to minimize the burnup reactivity swing. These optimizations lead to a decreased burnup reactivity swing that is as much as 82.5% less than the swing of non-BP-loaded core; furthermore, the maximum beam current is 12.5 mA. The reactor characteristics of the optimized BP-loaded ADS core are also analyzed to investigate how the introduction of BP assembly influences the system. Safety parameters (such as the Doppler coefficient and the coolant void reactivity) worsen with the introduction of BP assembly, and the total minor actinide transmutation amount decreases 30–40 kg because of the moderated neutrons and changed fuel composition.

The estimation of elasticity distribution in static elastography methods strongly depends on the shape of the transducer head. It is known that the insertion of a damper layer is effective in improving the spatial nonuniformity of an applied strain distribution. We have developed a new estimation method for assessing the effectiveness of this technique through structural analysis using the finite element method and acoustic analysis using the finite-difference time-domain method with multilayered tissues. From the results, the strain flatness inside the compressed tissue is markedly improved, especially near the tissue surface, by inserting a damper layer between the transducer and the tissue surface. The elasticity of an inclusion and the deeper region of a three-layer tissue are also adequately imaged.

The first stable anthryldiphosphenes, 1and 2, were synthesized by utilizing kinetic stabilization of 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt) groups, and were characterized by spectroscopic and X-ray crystallographic analyses. The UV–visible spectroscopic data suggested the electronic communication between the anthryl moiety and the P=P unit. It was found that TbtP=P(9-Anth) (1a: 9-Anth = 9-anthryl) showed weak fluorescence in hexane solution. Furthermore, the reactivities of anthryldiphosphene 1with a chromium complex, chalcogenation reagents, a diene, and electron-deficient olefins have been revealed.

Kinetically stabilized 1,1′-bis[(E)-diphosphenyl]ferrocenes were synthesized by taking advantage of extremely bulky substituents, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (denoted as Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (denoted as Bbt) groups, and characterized by the spectroscopic and X-ray crystallographic analyses. The electronic structures of the 1,1′-bis[(E)-diphosphenyl]ferrocenes were determined by analyzing electronic spectra, the transitions of which were reasonably assigned based on theoretical calculations. In the cyclic voltammograms, there were two well-defined reversible one-electron reduction couples corresponding to the intramolecular two diphosphene units. Furthermore, the 1,1′-bis[(E)-diphosphenyl]ferrocene was found to undergo ligand-exchange reactions with group 6 metal carbonyl complexes along with the E-to-Zisomerization of the diphosphene moieties, leading to the formation of the corresponding 1,1′-bis[(Z)-diphosphenyl]ferrocene group 6 metal tetracarbonyl complexes, [M(CO)4{(Z,Z)-(BbtP=PC5H4)2Fe}] (M=Cr, Mo, and W). The molecular structures of these complexes were determined by spectroscopic analyses (1H, 13C, and 31P NMR spectra, and UV–vis spectra), and that of the tungsten complex was determined by X-ray crystallographic analysis. Several types of d→π∗P=Pelectron transitions due to the iron and group 6 metals were detected by using UV–vis spectroscopy, and these results were supported by theoretical calculations.

The first stable 9-germaanthracene and 9-germaphenanthrene were successfully synthesized by taking advantage of kinetic stabilization utilizing effective steric protection groups, Tbt and Bbt groups (Tbt 2,4,6-trisbis(trimeth-ylsilyl)methylphenyl, Bbt 2,6-bisbis(trimethylsilyl)methyl-4-tris(trimethylsilyl)methylphenyl). The similarities and differences of the structures and properties between the two isomers of germaaromatics are discussed.

An effective method in static elastography for improving the nonuniformity of stress applied by the shape of a transducer head is to insert a damper between the tissue being analyzed and the transducer head. We previously demonstrated the effectiveness of inserting a damper through computer simulations of structural and acoustic analyses on tissue models with flat surfaces. In this study, the optimal values were obtained for two parameters of the damper: Young's modulus and damper thickness. An effective damper shape was also determined through structural analyses.

We describe the phase-noise characteristics and analyze a model of the Butler crystal oscillators and propose an oscillation circuit with two quartz crystal resonators for the Base terminal of a Butler crystal oscillator and evaluated the phase noise in the carrier vicinity. The experiment and simulation were able to be carried out using the Colpitts oscillators to reduce the phase noise. However, in the recent mobile communication, it was requested that the oscillators, which were a high frequency, and Butler crystal oscillators corresponded to probable circuits of the reliability. The Butler crystal oscillator using two quartz crystal resonators, it was only implementation in the simulation before. We decided to demand previous simulation by the experiment this time. This noise decreased to [?]22.5 dBc Hz[?]1 with our oscillation circuit compared with that with only one quartz crystal resonator during our simulation and experiment.

Traditional quartz crystal frequency references include a large, power-starving, oven-controlled crystal oscillator (OCXO), which base stations favor because of their excellent stability. We simulated a temperature-compensated crystal oscillator (TCXO) in the stress-compensated cut (SC-cut) resonator using the C and B mode frequencies. Power-conscious base-station manufacturers use the compensation circuit combination of TCXOs. The large frequency change in the B mode will be employed in temperature compensation for the C mode. First, we examined the circuit that could drive the C mode and B mode by simulation at the same time.

The first stable 9-anthryldiphosphene, TbtP=P(9-Anth) (1: Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, 9-Anth = 9-anthryl), was synthesized and its properties were revealed by spectroscopic and X-ray crystallographic analyses. The weak fluorescence of 1was observed in hexane solution.

A novel technique of detecting the peak frequency of an ultrasonic reflection spectrum was proposed, with the aim of enhancing the sensitivity and accuracy of estimating the aggregation size of red blood cells (RBCs). Peak frequencies for stagnant and running suspensions prepared with monodisperse particles of graphite and acryl that were used to mimic aggregated RBCs were acquired. As a result, the relationships between particle diameter and peak frequency, which were independent of the material of the particles and flow rate, were obtained. For bidisperse samples, i.e., mixtures of two different sizes of particle samples, quantitative relationships corresponding to changes in the mixing ratio were observed.

We developed a coaxial-type fixture for precisely measurement of the impedance characteristics of small surface-mounted quartz crystal units. This fixture is applicable to the one-port S-parameter reflection method proposed in IEC60444-5, and measures the frequency impedance characteristics of a device under test (DUT) from its reflection coefficients. This measurement fixture uses a 65 GHz coaxial connector and calibrators with a 1.85 mm inside diameter. Using a “zero-length” coaxial center pin method, this fixture can be applied to up to 2 GHz devices without the need for electrical length compensation.

The first stable anthryldiphosphenes [cf.

In this paper, a quartz crystal microbalance (QCM) gas sensor using multiple resonant modes is studied. In this QCM gas sensor, the absorbent is not fully deposited onto the plate surface as in the case of conventional QCM gas sensors. The absorbent is coated on the plate surface, where the external-stress-sensitivity difference between the two modes used is greatest. To confirm the validity of multimode QCMs, we fabricated multimode QCM devices; a polyimide thin film is used as the adsorbent of carbon dioxide, and an 11 MHz AT-cut quartz resonator is used.

In this paper, the effect of stepped bi-mesa structures on the coupling of vibrations in AT-cut quartz plates is analyzed theoretically. Since strong coupling of thickness-flexure modes are of interest, straight-crested waves propagating along the Xaxis are treated. Calculated results for the stepped bi-mesa structure show that the coupling strength as estimated from its mode chart decreases to about one-third that of a bi-mesa resonator. The characteristics of bi-mesa structures appear to be amenable to further improvement by the use of a stepped bi-mesa structure.

A method for measuring the mode shapes of quartz crystal resonators using an electrostatic microphone is described. In this method the resonator driving current is strongly modulated, and a needle connected to the microphone picks up the modulation signal on the resonator surface. The vibrational patterns are obtained by mapping the detected modulation signals on the resonator surfaces. The experiments were carried out using AT-cut rectangular quartz plates and the results were compared with those from the calculations.

In this paper, we describe a method for detecting weak spurious modes in quartz plates. This method picks up the weak modes by measuring the frequency characteristics of high-frequency charge voltages, which are excited at resonant frequencies, at many points on the plate surface. The measured results for two strip AT-cut quartz resonators show that this method can detect very small resonance modes undetectable by conventional methods.

Strip AT-cut quartz resonators have recently been developed and are widely used in frequency applications because of their small size. Many spurious resonances can be supported in a rectangular AT-cut plate. Therefore, analysis of the influence of both the Xand Z'dimensions of the plate upon the spurious characteristics is necessary to design the strip resonators. However, it is very difficult to exactly solve three-dimensional equations of elasticity. The practical analysis of spurious characteristics has been carried out on the basis of approximate two-dimensional equations. In this paper, the applicability of Lee's two-dimensional equations to AT-cut plates is examined. The resonant frequencies are calculated as a function of X-length, and are compared to Koga's experimental data. The result shows that new correction factors should be introduced in the equations in order to adjust the approximate values of wave numbers for the thickness-flexure waves propagating in Xand Z'directions.

This paper describes a precise method of determining the supporting position of a stress compensated (SC) cut crystal wafer using a semiconductor pulsed laser. Because the supporting position greatly influences the frequency stability against acceleration and/or external stress, an accurate determination method is required. The experimental results for circular SC-cut quartz resonators with various supporting positions demonstrate the validity of this technique.

A new method for measuring the stress sensitivity distribution on a resonator surface, including a region without electrodes, using a low-frequency sound wave is described. The experimental results for an AT-cut quartz crystal resonator obtained using the proposed method and the current pulsed-laser method are shown. Additionally, we applied this method to the design of quartz crystal microbalances using multiple resonance modes.

The method described here accurately determines the two-dimensional surface charge pattern of a weak mode existing in the vicinity of a strong mode in quartz crystal plate using an equivalent model that suitably approximates the surface charge frequency characteristics in the target modes measured at each measurement coordinate. The surface charge frequency characteristics are measured by an automated measurement system based on the electrical probe method. The temperature characteristics of the measured surface charge pattern of a weak mode near the fundamental thickness-shear mode in a rectangular AT-cut plate demonstrated that even for a weak mode, the present procedure provides patterns clearer than those obtained with a previous technique.

A laser-diode-based system for measuring the patterns of in-plane vibrational displacement in quartz resonators is described. This system utilizes the force-frequency effect in detecting the displacement. Its employment of a semiconductor laser-diode module makes the measurement fixture very simple and compact. The experimental results for a very-high-frequency AT-cut quartz resonator demonstrate the validity of this system.

We have developed a technique for the three-dimensional (3-D) analysis of all the spurious vibrations of rectangular AT-cut quartz plates. The 3-D displacements are described with a linear combination of modes guided along the Xcrystal axis of an AT-cut quartz strip. We accurately calculate each guided mode by applying the one-dimensional finite element method to the two-dimensional strip waveguide problem. To uniquely determine the amplitudes of guided modes in the 3-D solutions we employ the variational expression for the stress-free conditions on the X-length edges. The present technique makes it possible to perform 3-D analysis of spurious vibrations within a reasonable computational time. Frequency spectra for rectangular AT-cut quartz plates are computed as a numerical example and are compared with the numerical results obtained using an extended version of the previous method and with Koga's experimental data. Vibrational patterns of spurious modes are shown, and a convergence study is carried out.