Narrow Results

$\tau$ lepton is one of three charged leptons in nature, the measurements of its mass have been performed since its discovery. The present relative accuracy is already at the level of $10^{-4}$; more factors are still being studied in order to increase the accuracy. However, the available techniques for analysis and expectable luminosity from e${}^{+}$e${}^{-}$ collider indicate that the precision upper limit of $\tau$ mass is almost reached, which means that brand new approaches should be considered if a great improvement is yearned for.

The Beam Dynamics simulation package in COSY INFINITY is built upon a differential algebra data type. With it, it is possible to compute transfer maps or arbitrary systems to arbitrary order. However, this data type is limited by the precision of the underlying floating point number model provided by the computer processor.

We will present a method to extend the effective precision of the calculations based purely on standard floating point operations. Those algorithms are then integrated into the differential algebra data type to efficiently extend the available precision, without unnecessarily affecting overall efficiency. To that effect, the precision of each coefficient is adjusted automatically during the calculation.

We will then proceed to show the effectiveness of our implementation by calculating high precision maps of combinations of homogeneous dipole segments, for which the exact results are known, and comparing the high precision coefficients with the results produced by the traditional COSY beam physics package.

The CEPC booster will accelerate the $e^{-}{e}^{+}$ beam from 10 GeV to 120 GeV, so the field of the dipole magnets will change with the beam energy, of which the minimal working field is 29 Gs whereas the maximal field is 338 Gs. To reach the requirement of high precision at lower field level, three kinds of new dipole magnets are proposed and studied. To test and verify the designs of the magnets, two subscale prototype magnets are fabricated.

A high precision fast projective synchronization method for chaotic systems with unknown parameters was proposed by introducing optimal matrix. Numerical simulations indicate that the precision be improved about three orders compared with other common methods under the same condition of software and hardware. Moreover, when average error is less than 10^-3, the synchronization speed is 6500 times than common methods, the iteration needs only 4 times. The unknown parameters also were identified rapidly. The theoretical analysis and proof also were given.

In order to increase more greatly the measurement accuracy for the laser tracking system in measuring the moving body, a laser beat-wave interferometry method is approached based on the absolute measuring distance. The He–Ne laser with the two hot steady frequency modes is used as the light source for the laser tracking system. The light source developed by us not only has the advantages of steady frequency, high precision and strongly anti-interference capability, but also it mainly has the same character in the shoot stability degrees and laser frequency stability degrees. By using the laser beat-wave interferometry method, we can realize the absolute distance measurement of the moving body, and the laser tracking system has very high measurement precision, fast tracking speed and anti-interference capability.

Acoustic wave measurement technology is the supporting technology in acoustic wave field. It is important to study acoustic wave with high precision and reliability testing equipment and scientific testing methods. The mathematical model of this acoustic wave measurement system was analyzed on the building of the system. The BP neural network algorithm was used in order to attain the higher accuracy for the acoustic wave measurement system. Frequency domain calibration was carried out by which the amplitude/frequency character curve of this system could be obtained. Then the model of the system was established by BP neural network algorithm. Finally, the validity of the established model was tested. The conclusion was that the math model reflected the original acoustic wave measurement system’s character through the regression result in the frequency domain.

A design of digital application specific integrated circuit (ASIC) of quartz-gyro is proposed in this paper. The digital drive circuit with fast-start oscillation and digital detection circuit with low noise are adopted to implement the digital output of the main circuit node and high precision angular velocity detection. The interface circuit is fabricated in a standard 0.35 $\mu$m CMOS technology and test result shows the angular random walk and zero stability are $0.022^{\circ }$/$\sqrt{\mathrm{\text{h}}}$ and $2.9^{\circ }$/h ($1\sigma$), respectively. The bias-instability is $1^{\circ }$/h (Allen). The nonlinearity is limited to 0.035% and the zero temperature drift is $16^{\circ }$/h from $-45^{\circ }\mathrm{\text{C}}$ to $85^{\circ }\mathrm{\text{C}}$. The chip exhibits great superiority on the aspects of high precision angular velocity digital detection and temperature characteristics of overall system.

There is an increasing demand for biometric security systems in several fields. This study presents a highly accurate facial recognition method that uses high-speed transformation and facial morphing using region-limited log-polar transformation based on a center point calculated from the coordinates of both eyes and corners of the mouth. Log-polar transformation is limited to the region, so that the region including the feature can be suppressed to the minimum range, thereby facilitating high-speed transformation. Additionally, after facial morphing, the shapes of the eyes and mouth are altered based on the outline of the face, enabling high-precision facial recognition. The efficacy of the proposed method is verified experimentally. Therefore, we can confirm that 91.72% of images using the color FERET database and 96% of images using the FEI face database can be recognized using our method.

This paper presents a new high speed voltage-mode MAX–MIN method for fuzzy applications. In the proposed circuits, a differential pair is employed to choose the desired input. In addition to high speed, high precision and simple expansion for multiple inputs are the main advantages of this method. HSPICE simulation results show that the proposed circuit has maximum of 1% error at 100 MHz.

The Arctangent function is used in several signal processing applications and it is widely needed for hardware implementations. However, it often constitutes the performance bottleneck because of its inaccuracy and/or its poor performances. We present a generic VLSI design to respond to some applications' need of fast Arctangent functions handling high precision data. The method presented here contrasts with the usual Look Up table based solutions which allow the output customization but limit the precision of the corresponding tangent input. Detailed logical design and FPGA implementation results are provided to show our solution as the best candidate to comply with fast execution as well as high precision for both input and output data.

With the application of the voltage divider to the traditional bandgap reference without resistors, a high precision CMOS voltage reference without resistors has been proposed. The temperature coefficient has improved because the divider introduces the temperature compensation. The output reference voltage is 410.39 mV at the room temperature. The temperature coefficient of the voltage reference is 3.02 ppm/°C in the range from -20°C to 120°C. Moreover, the power supply rejection ratio of the voltage reference is -52.6 dB and the power consumption is 5.61 μW.

A novel digital constant output current controller with demagnetization-time compensation for flyback converter is proposed in this paper. The secondary winding demagnetization time $T_d(n)$ is sampled from the comparison module output signal by output voltage sampling state machine. The ratio between $T_d(n)$ and switching period $T_s(n)$ is kept constant by bidirectional counter module to achieve constant output current based on invariable primary-side peak-current. Meanwhile, demagnetization-time compensation is proposed in order to enhance load regulation ratio. The compensation $\mathrm{\Delta }{T}_s(n)$ acquired from a look-up table, is utilized to compensate the impacts caused by the delay $\mathrm{\Delta }t$ from the process of sampling the signal of $T_d(n)$. The digital controller (DC) is implemented by hardware description language Verilog HDL. Experimental results of the proposed 2A constant current output flyback converter based on FPGA(EP2C8Q208C8N) indicate that the constant current precision is within $\pm$1% in a wide range of universal-input AC voltage from 110V to 240V and the voltage load range between 2V and 8V.

High precision structural displacement monitoring is challenging, but an effective method for structural health monitoring and particularly damage evaluation. In this paper, a high precision fiber Bragg grating (FBG) displacement sensor with embedded spring is developed to monitor structural displacement variation even at very small ranges. The principle of such monitoring is based on the central wavelength shifts in accordance with the displacement between measuring points. Calibration experiments are conducted to examine the performance of the innovative displacement sensor. The result indicates that the sensor has excellent linearity and repeatability, with the sensitivity coefficient being 23.96pm/mm, and the static relative error is 4.94% after three loading and unloading cycles. The displacement sensor therefore shows an excellent sensitivity and high precision for application. Moreover, it has been verified that this sensor is suitable and applicable for displacement monitoring in quasi-static experiment of structures.