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Mechanical oscillators can be implemented to store and transfer information or to build hybrid systems. In order to couple a mechanical oscillator to a superconducting qubit, we fabricate a superconducting capacitor, in which diluted photoresist or electron beam photoresist is used as sacrificial layers. The upper plate of the capacitor, a suspended membrane, acts as a mechanical oscillator. We obtain its mechanical resonant frequency and response to the input microwave. Such mechanical oscillators can be used as the capacitor of a superconducting qubit to form a coupled system. In order to control the resonant frequency of the mechanical oscillator and the microwave resonator, we introduce a dc voltage bias between the upper and lower plates of the capacitor. We analyze the electromechanical coupling such as pull-in effect and experimentally demonstrate the dependence of the resonant frequency on the applied dc voltage. These results will contribute to the design and fabrication of hybrid systems comprising voltage-controlled mechanical oscillators and other systems.

An impedance matched parametric amplifier (IMPA) with Josephson junctions is fabricated and characterized. A hybrid structure containing coplanar and strip structures is implemented to realize an impedance taper line and a plate capacitor in an LC nonlinear resonator based on Josephson junctions. The upper plate of the capacitor is isolated with SiN x without grounding as well as the strips. Such easily-prepared designs greatly reduce the requirements for lithography alignment and precision, which makes the fabrication process more reliable. The experimental results show that in such IMPA a gain higher than 25 dB with a bandwidth of about 100 MHz can be obtained. This broadband amplifier operates close to the quantum limit. By adjusting the working point, a higher bandwidth of about 400 MHz can be obtained with a gain of about 17 dB.

We design and fabricate λ/2 coplanar waveguide NbN resonators, the thickness and length of which are only several nanometers and hundred microns, respectively. The quality factor of such compact resonators can reach up to 7.5 × 104 at single photon power level at 30 mK with the resonance frequency around 6.835 GHz. In order to tune the resonant frequency, the resonator is terminated to the ground with a dc-SQUID. By tuning the magnetic flux in the dc-SQUID, the effective inductance of the dc-SQUID is varied, which leads to the change in the resonant frequency of the resonator. The tunability range is more than 30 MHz and the quality factor is about 3 × 103. These compact and tunable NbN resonators have potential applications in the quantum information processing, such as in the precision measurement, coupling and/or reading out the quantum states of qubits.

Accurate calculation of the vehicle load is the foundation for the middle and small bridge safety. Longitudinal influence line and transverse distribution coefficient are used in traditional calculation method of vehicle load. This method brings a little big error because of the simplification. A new method based on influence surface is offered in this paper. The analysis results show that the new method can meet more accurate demand.

The transverse distribution of lane loading is one of the most concern for the assembly prefabricated T-girder bridges. Longitudinal influence line and transverse distribution coefficient are used in the traditional calculation method of lane loading effects. But, many research results show this method brings a little big error because of the simplification. Along with the advance of computer technology in mathematics, it is not difficult to use the 3D FEM model to calculate the inner force that caused by vehicle load in girder bridge. In this paper, some comparatively accurate 3D FEM models are established to analyze the lane loading effects on the simply supported T-girder bridge. The results show that the moment and shear force of each girder are quite different between traditional method and 3D FEM model. The results indicate that the traditional method in current code is non-conservative.

Oil dampers are widely used as a popular countermeasure to mitigate the stay cables vibration. In this study, one actual oil damper designed for some long cable-stayed was experimentally investigated to evaluate the durability. 4 million cycles loading, with frequency of 4 Hz and amplitude of 1 mm, was imposed on the damper. The excitation displacement and damping force were measured and the equivalent damping was calculated from the experimental results. The stiffness effects of dampers behaved during durability tests were also analyzed quantitatively. The test results showed that the dampers were still in good condition after 4 million cycles loading and the dampers temperatures were stable at 50 degree centigrade during the test. According to the durability test results, a model for performance deterioration of damper was proposed to predict the lifetime of oil dampers.