(1) School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China; (2) School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China

In the industrial field we need to know working conditions of equipments comprehensively and accurately. The operating parameters are generally obtained through the data acquisition system. With the development of technology, people demand higher accuracy of the data acquisition system. Besides, some data acquisition systems often fail to achieve the nominal accuracy. In this paper, a self-developed data acquisition system is chosen as the experimental equipment, and its accuracy of AD is assessed by the actual data. On this basis, we analysis the types of the errors，which mainly include random error and system error. And finally the accuracy of the data acquisition system is improved through operating software compensation. The system then can be used in the real workplace.

In this paper, graphene grown by Chemical vapor deposition (CVD) on a Cu foil in a cold-wall furnace was used to fabrication the graphene strain gauge. The graphene membrane was patterned to wire grid shape on the Cu substrate by photolithography method in the clean room. The pattern was transferred to PDMS substrate and seal by it also to make graphene in a stable surroundings. Through the standard calibration, it was calculated that the linearity and multiplicity of the graphene strain gauge both were 0.0076%F.S.. Which indicated the good quality of the gauge. The gauge factor was 2.4, as the highest value as that of the alloy strain gauge. We also find the graphene strain gauge output increase proportionally with increasing curvature of its deformation.

In practice the method is widely used, by which a gravity is measured using multiple load cells. A weighing system is introduced in this paper, in which a gravity is measured by multiple load cells with digital addition. The mathematical model of weighing system with digital addition is established. Normal calibration method is not suitable for the on-line calibration of weighing system with digital addition. When the mathematical model is given, the accurate on-line calibration of weighing system with digital addition is achieved by using optimization method.

In this paper, we report an improved transfer of graphene by directly picking up the graphene with target substrates and the comparison of such transferred graphene samples with other graphene samples transferred by the commonly used "PMMA-based transfer" method. Raman spectroscopy studies show that this "direct transfer method" does not degrade the graphene structure and field effect transistor measurements show that it does not introduce any extra doping in graphene; in contrast, PMMA-based transfer samples have strong n-type doping. We also find that graphene samples achieved by this direct transfer method show higher mobility than graphene obtained from the PMMA-based transfer method.

Graphene grown by chemical vapor deposition on a Cu foil and transferred onto a Si wafer has been used to fabricate a field effect transistor device that was used to study the sensing of SO2 gas. It was found by in-situ measurements that the SO2 strongly p-dopes the graphene and dramatically shifts its Dirac point. This effect was used to monitor the SO2 gas. The detector can be completely reset by thermal annealing at 100 °C in high vacuum. The response and recovery of the detector are faster at higher temperatures. Moreover, the sensitivity of the SO2 graphene detector increases proportionally with increasing temperature.

By using the key technology of wireless sensor networks, a stress test system was designed, which takes the M2110 wireless sensor networks as a platform. Based on the hardware design and software design of TinyOS2.0 sensor nodes and gateway nodes, the signal transmission performance of wireless sensor networks for the stress test system was tested and researched. In the visual conditions, the maximum communication distance of M2110 wireless node is up to 601 meters. In the non-visual conditions, M2110 wireless node also has a certain signal transmission capacity. On the situation of multi-hop nodes network, the success rate of data transfer has relation to the transmission rate of data packet and the number of hops for nodes.

By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould, friction between mould and shell can be determined. The condition of solidified shell can be monitored by thermocouples fixed to the mould. Breakouts, whether caused by shell cracking, shell sticking or entrained impurities, can therefore be predicted and effectively avoided through monitoring the change characteristics of friction and thermocouples temperature during the process.

By analyzing the reasons for the position of the breakout of sticking,crack and something abnormal involved in,and the slab shell of the characteristic,a new type of forecast system was developed to forecasting the breakout of the sticking,the cracks(longitudinal and angle) and something abnormal involved in.

Optimal design of hollow cylinder type force transducer with ultra low height is feasible and successful. The force transducer with ultra low height can be used to heavy duty machinery and constructive engineering. It is necessary to optimize force transducer with ultra low height. Choosing inner radius and wall-thick as design variables, maximum strain of cylinder is objective function and the active constraint is suitable. The experiment results show that linearity is improved.

There are many monitoring objects with vibration frequency under 5Hz in the engineering application. Their monitoring accuracy and reliability depend on the accurate calibration of vibration measurement system in the low-frequency vibration. When a conventional standard vibrator vibrates under 5Hz frequency, the contact acceleration sensors, as a compared datum, have the output signal with clear distortion. By using the non-contact eddy current sensor which was accurately calibrated as a compared datum, it is determined that the standard vibrator can achieve a regular sinusoidal vibration at the frequency of 1~5Hz. If the output signal of the contact sensors for measuring vibration is processed (filtering and smoothing), the standard vibrator can be used to calibrate the vibration measurement system at the frequency of 1~5Hz.

Piezoelectric accelerometers are widely used for the measurement of middle- or high-frequency vibration. It is necessary to verify via experiments whether piezoelectric accelerometers can accurately measure low-frequency vibration. An experiment is designed to test the output characteristics of piezoelectric accelerometers for vibration of 1~5 Hz frequency, using a standard vibrator at low frequency (≤5Hz) and an accurately calibrated non-contact eddy current sensor as datum sensor. The experiment shows that the output characteristics of piezoelectric accelerometers are relatively stable when measuring vibration of 4~5Hz frequency. However, the output characteristics of accelerometers change with the frequencies and accelerations of vibration when the vibration frequencies are 1~3 Hz. It will affect the accuracy of vibration measurement.

The deposition effect of metals on graphene was studied by in situ field effect transistor (FET) measurements in high vacuum. Metals such as gold (Au), silver (Ag), and copper (Cu) were deposited onto clean graphene surfaces, followed by FET measurements. The results show that Ag and Cu cause a shift in the Fermi level in the graphene from the Dirac point into the conduction band while Au causes a shift into the valence band. The induced carrier concentration was estimated at 2–6×1012/cm2. The shifts in the Fermi level of the graphene are explained by the different work functions of these metals.

The pressure of hydraulic servo cylinders and the position of their pistons,which were measured in hydraulic servo oscillation systems on the slab continuous casters,were substituted in the motion equation of hydraulic servo vibration systems to determine the frictional force between the mold and slab shell.The change characteristics of frictional force were found before the molten steel breakout.The characteristics can be used to the forecasting and reduction of molten steel breakouts.

Heavy duty machinery and constructive engineering need low height force transducer to measure great force. Because assembling space is not enough, it is necessary to design a special force transducer. Thus, hollow cylinder type force transducer with ultra low height is designed and experimented especially. The ratio of the height of hollow cylinder-type force transducer to the diameter of hollow cylinder-type force transducer is limited to less than 7/4. To break the limitation, two cases of the transducer are designed and studied, experimented data are processed by MATLAB.

The pressure of servo-hydraulic cylinders and the position of their pistons are measured in servo-hydraulic oscillation systems on the slab continuous casters. They are substituted in the motion equation of servo-hydraulic oscillation systems to determine the frictional force between the mould and slab shell. The change characteristics of frictional force are found, which were before the molten steel breakout. The characteristics can be used to the forecasting of molten steel breakouts, so that the molten steel breakouts are remarkably reduced.

Considering the advantages and disadvantages of both constant-current charging and constant-voltage charging mode for storage battery. The intelligent control system of quick charging is designed to adjust pulse width automatically. Comparing with constant current-constant voltage charging mode ,technology quick charging system have shorter charging time, higher charging efficiency.

本文通过结晶器液压伺服振动系统在拉钢过程中摩擦力大小的研究,找出结晶器与坯壳间摩擦力的变化特征来预报粘结、裂纹及异物卷入漏钢,并得出漏钢预报报警后板坯拉出结晶器不漏钢的必要条件.

On base of studying the weighing system of multiple load cells under "all-parallel manner", a method is put forward to reduce the measurement error of the weighing system in this article,that is applying series resistor to input of bridge circuit to adjust the actual bridge voltage of load cells. Then the effective sensitivities of load cells keep pace with each other. In this way, the weighing system can achieve higher measurement accuracy under the circumstances of uneven load.