A Prototype of beam position and phase measurement electronics for the LINAC in ADS

This article presents a prototype of beam position and phase measurement(BPPM)electronics designed for the LINAC in China Accelerator Driven Sub-critical system(ADS).The signals received from the Beam Position Monitor(BPM)detectors are narrow pulses with a repetition frequency of 162.5 MHz and a dynamic range more than40 dB.Based on the high-speed high-resolution Analog-to-Digital conversion technique,the input RF signals are directly converted to In-phase and Quadrature-phase(IQ)streams through under-sampling,which simplifies both the analog and digital processing circuits.All signal processing is integrated in one single FPGA,in which real-time beam position,phase and current can be obtained.A series of simulations and tests have been conducted to evaluate the performance.Initial test results indicate that this prototype achieves a phase resolution better than 0.1 degree and a position resolution better than 20μm over a 40 dB dynamic range with the bandwidth of 780 kHz,which is well beyond the application requirements.

Research into the sampling methods of digital beam position measurement

A fully digital beam position monitoring system(DBPM) has been designed for SSRF(Shanghai Synchrotron Radiation Facility). As analog-to-digital converter(ADC) is a crucial part in the DBPM system, the sampling methods should be studied to achieve optimum performance. Different sampling modes were used and compared through tests. Long term variation among four sampling channels, which would introduce errors in beam position measurement, is investigated. An interleaved distribution scheme was designed to address this issue. To evaluate the sampling methods, in-beam tests were conducted in SSRF. Test results indicate that with proper sampling methods, a turn-by-turn(TBT) position resolution better than 1 μm is achieved, and the slow-acquisition(SA) position resolution is improved from 4.28 μm to 0.17 μm.

Design and Implementation of Digital Fractional Order PID Controller Using Optimal Pole-Zero Approximation Method for Magnetic Levitation System

The aim of this paper is to employ fractional order proportional integral derivative(FO-PID)controller and integer order PID controller to control the position of the levitated object in a magnetic levitation system(MLS),which is inherently nonlinear and unstable system.The proposal is to deploy discrete optimal pole-zero approximation method for realization of digital fractional order controller.An approach of phase shaping by slope cancellation of asymptotic phase plots for zeros and poles within given bandwidth is explored.The controller parameters are tuned using dynamic particle swarm optimization(d PSO)technique.Effectiveness of the proposed control scheme is verified by simulation and experimental results.The performance of realized digital FO-PID controller has been compared with that of the integer order PID controllers.It is observed that effort required in fractional order control is smaller as compared with its integer counterpart for obtaining the same system performance.

Simulation and Design Optimization of Novel Microelectromechanical Digital-to-Analog Converter

A microelectromechanical Digital to Analog Converter (DAC) based on Weighted Gap (WG) principle is described,which is analogous to the weighed resistor DAC in electronic circuits.To convert the input of binary voltage to the output of analog displacement,the gaps are proposed to be employed as a scale factor.A finite element method is used to simulate the performance of the DAC.To reduce the error,the structure design is optimized and the maximum error of 0 002μm is obtained.

Design and measurement of signal processing system for cavity beam position monitor

In this paper,in order to achieve the output signal processing of cavity beam position monitor(CBPM),we develop a digital intermediate frequency receiver architecture based signal processing system,which consists of radio frequency(RF) front end and high speed data acquisition board.The beam position resolution in the CBPM signal processing system is superior to 1μm.Two signal processing algorithms,fast Fourier transform(FFT) and digital down converter(DDC),are evaluated offline using MATLAB platform,and both can be used to achieve,the CW input signal,position resolutions of 0.31μm and 0.10μm at -16 dBm.The DDC algorithm for its good compatibility is downloaded into the FPGA to realize online measurement,reaching the position resolution of 0.49μm due to truncation error.The whole system works well and the performance meets design target.

A beam position measurement system of fully digital signal processing at SSRF

This fully digital beam position measurement instrument is designed for beam position monitoring and machine research in Shanghai Synchrotron Radiation Facility. The signals received from four position-sensitive detectors are narrow pulses with a repetition rate up to 499.654 MHz and a pulse width of around 100 ps, and their dynamic range could vary over more than 40 dB in machine research. By the employment of the under-sampling technique based on high-speed high-resolution A/D conversion, all the processing procedure is performed fully by the digital signal processing algorithms integrated in one single Field Programmable Gate Array. This system functions well in the laboratory and commissioning tests, demonstrating a position resolution (at the turn by turn rate of 694 kHz) better than 7 μm over the input amplitude range of -40 dBm to 10 dBm which is well beyond the requirement.

A Micro Study to Determine Porosity, Hydraulic Conductivity, Permeability and the Discharge Rate of Groundwater in Ondo State Riverbeds, Southwestern Nigeria

Laboratory study of three riverbed soil samples denoted as A, B and C have been carried out by determining the soils Porosity, Hydraulic conductivity, Permeability and also investigating if there are points of convergence between the discharge rate and angle of tilt for the above mentioned samples. The experimental results for Porosity were approximately within 34% - 37%, Hydraulic conductivity was within 3.02 × 10-5 - 9.70 × 10-5 (m/s) and Permeability was within 2.74 × 10-12 - 8.80 × 10-12 (m2). Pressure generally increases as distance of flow increases for θ = 5° - 25° but there was decrease in pressure as distance of flow increases for all three samples when θ = 0°. The points of convergence for the discharge rate ranged from 0.001 × 10-10 - 4.54 × 10-10 (m3/s), while the angle of tilt convergence points ranged from 0.1° to 3.6°. There was increase in discharge rate as angle of tilt increases for all three samples.

Cubic Root Extractors of Gaussian Integers and Their Application in Fast Encryption for Time-Constrained Secure Communication

There are settings where encryption must be performed by a sender under a time constraint. This paper de-scribes an encryption/decryption algorithm based on modular arithmetic of complex integers called Gaus-sians. It is shown how cubic extractors operate and how to find all cubic roots of the Gaussian. All validations (proofs) are provided in the Appendix. Detailed numeric illustrations explain how to use the method of digital isotopes to avoid ambiguity in recovery of the original plaintext by the receiver.

A GPS-Based Digital Dynamics Study of the Rugby World Cup 2019 Spectators

This study’s dynamic survey of spectators at the HRS(Hanazono Rugby Stadium)in HOC(Higashi Osaka City)during the 2019 RWC(Rugby World Cup)tournament used location information big data to analyze nine items,including spectator attributes-60 min or more stay in HOC(excluding residents),more than 15 min stay in the HRS on match days(besides,the days before and after the match).To compare spectators,visitors to HOC during the matches were added to the target group.The results show that the RWC attracted a high number of male visitors aged 20,40,and 50 years,mainly from the Kinki region,whose stopovers inside and outside the region were limited to Osaka City.Stopovers in tourist areas unrelated to the RWC were few,partly because it was possible to undertake a day trip solely to watch the game without any stopovers.

Implementation and integration of a systematic DBPM calibration with PLL frequency synthesis and FPGA

Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM(Beam Position Monitor) processor deteriorates the BPM performance.A systematic solution based on signal source calibration tactics has been carried out to rectify this defect.It is optimized for implementation in FPGA.Mathematical illustrations of the calibration method,hardware and software design and implementation are presented.A signal source circuit using frequency synthesis technique is designed as calibration standard.Data acquisition system using JAVA web technology and Ethernet is introduced.Integrated FPGA implementation code architecture is presented,and experimental test results show that the method implemented in FPGA is feasible.Compared to other methods,our approach can rectify the nonlinearity and asymmetry simultaneously.The whole solution is integrated into the DBPM processor and can be executed online.

An Intermediate Frequency Acquisition Scheme for S-band Single Access Link of the Tracking and Data Relay Satellite System

A nonzero intermediate frequency (IF) likelihood acquisition scheme designed for S-band Single Access (SSA) link of China’s Tracking and Data Relay Satellite System (CTDRSS) is introduced. The received signal is downconverted to IF, and then direct sampled in IF using a 1-bit A/D. After the digitalization, the sampled data is detected using a hybrid likelihood acquisition scheme. Using this structure, large noise figure of the analog mixer or active filters, amplitude and phase imbalance between low-frequency in-phase and quandrature-phase channel can be avoided. An easy designing algorithm of the acquisition scheme is also derived. The performance and algorithm are verified by computer simulation.

Pure Digital Control for the Outer Axis of a Three-Axis Flight Simulation Table

In this paper, a pure digital control method for the outer axis of a three-axis flight simulation table is worked out and a state observer is used to obtain the acceleration signal. The method is simple and easy to be emplayed, and especially suitable for the electrohydraulic (?)ervo-system with fast response. The simulation results show that the system given in this paper has optimal three-order system performance.

Digital Trade Rules and the Position of Chinese Enterprises in the Global Value Chain

Digital trade rules and higher positions of enterprises in the global value chain(GVC)are both important topics in the context of high-quality economic development.This paper refers to the data of RTA digital trade rules concluded by China in the TAPED database in 2000-2014 and the matched data in the WIOD database,the China Customs Import and Export Database and the China Industrial Enterprise Database to investigate the effects of digital trade rules on Chinese enterprises as to their ascending GVC positions.It finds that signing the RTA digital trade rules can steadily and significantly promote the position ascendance;compared with the digitalization rules on trading objects,signing the digitalization rules on trade modes produces greater effects of driving up the positions,which are realized mainly via the three channels of advancing cross-border flow of R&D factors,promoting corporate digital transformation,and improving professional management.Digital trade rules that are horizontally broader and vertically deeper are in greater favor of Chinese enterprises for ascending in the global value chain,which is especially evident among those in digital industry and processing trade.During the negotiations of digital trade rules,it's imperative to pay close attention to the rules on e-commerce cooperation,awareness of e-commerce importance,intellectual property protection,attempts in big data-related trade in goods,and cross-border data flow,so as to secure the core interests of Chinese enterprises in gaining higher positions.This paper offers great policy implications as to how to sign digital trade rules by China in the future and how to select partners in greater support for Chinese enterprises to ascend to the middle and high end of the global value chain.

The characteristics of gully erosion over rolling hilly black soil areas of Northeast China

In this study,short-term gully retreat was monitored from the active gullies selected in representative black soil area,using differential global positioning system(GPS).With the support of geographic information system(GIS),multi-temporal digital elevation models(DEM) were constructed from the data collected by GPS and used for further analysis.Based on the analysis of multi-temporal DEM,we discussed the erosion-deposition characteristics within gully and a developing model for black soil gully area of Northeast China was proposed.The results are:(1) The analysis of the monitored gully data in 2004 indicated that the retreat of gully head reached more than 10 m,gully area extended 170-400 m2,net gully eroded volume 220-320 m3,and gully erosion modulus 2200-4800 t?km?2?a?1.(2) Compared with the mature gully the initial gully grows rapidly,and its erosion parameters are relatively large.The erosion parameters have not only to do with flow energy,but also with the growth phase.(3) There are significant seasonal differences in gully erosion parameters.The extension of gully area and width dominates in winter and spring without marked net erosion while changes mainly occur in gully head and net erosion in rainy season.(4) It is remarkable for freeze-thaw erosion in the black soil area of NE China.The gully wall of SG2 extended 0.45 m under freeze-thaw effect in 2004,and the distance of gully head retreated maximally 6.4 m.(5) Due to freeze-thaw action and snowmelt,gully is primarily in the interior adjustment process in winter and early spring.There are much more depositions compared with that during rainy season,which can almost happen throughout the gully,while erosion mostly occurs near head,esp.for gullies having a relatively long history of development.On the other hand,the process of energy exchange with exterior dominates in rainy season.It is considered that this cyclic process is an important mechanism for gully growth in high latitude or/and high attitude regions.

Applications of RS, GPS and GIS to Forest Management in China

Applications of remote sensing (RS), global positioning system (GPS), geographic information system (GIS) and combination of three-S techniques in the forest management are introduced. It indicates that, with the quickly improvement of the computer technique, the three-S system will become a very important part of the forestry management system.

Influence factors of two dimensional position map on photomultiplier detector block designed by quadrant sharing technique

The position decoding accuracy and the spatial resolution of positron emission tomography detectors are greatly influenced by the performance of the two-dimensional position map,including the gain uniformity of photomultiplier tube (PMT),the baseline offset of the PMT signals and the accuracy of analogue to digital converter (ADC).In this work,a PMT-quadrant sharing detector was designed.Two data acquisition platforms are employed to conduct the influence factors on the two-dimensional position map performances,one was that the waveforms of the PMT signals were scanned by the sequence acquisition mode based on the oscilloscope of LeCroy waveRunner 204MXi-A,and another was a self-developed high speed ADC data acquisition module.Results show that the event decoding positions were concentrated on the PMT with higher gain,the position map was distorted at the baseline offset of signal,and the cross-line artifacts were caused by the insufficient ADC sampling bit for a larger size position map.All the parameters need be adjusted properly to stabilize a real system,and the flexible oscilloscope platform can be used to design the detector block and the other platform with high ADC accuracy.Likely,the electrical circuit with a proper ADC accuracy adjusts the PMT gains and baseline offsets.

Effect of Altitude Error on Position Precision of Double-Star Position System

The effects of two kinds of methods for obtaining altitudes on the position precision are analyzed, and the error expressions are deduced. Many simulation results show that in the two cases, the effects of the same altitude errors on the positioning precision are identical, and the rules that the two altitude errors affect positioning precision can be expressed as that altitude error has little effect on the east-west position error, but has large effect on the south-north position error.

Research on new software compensation method of static and quasi-static errors for precision motion controller

To reduce mechanical vibrations induced by big errors compensation, a new software compensation method based on an improved digital differential analyzer (DDA) interpolator for static and quasi-static errors of machine tools is proposed. Based on principle of traditional DDA interpolator, a DDA interpolator is divided into command generator and command analyzer. There are three types of errors, considering the difference of positions between compensation points and interpolation segments. According to the classification, errors are distributed evenly in data processing and compensated to certain interpolation segments in machining. On-line implementation results show that the proposed approach greatly improves positioning accuracy of computer numerical control (CNC) machine tools.

Digital Radio Broadcasting for Community Radios Using Pseudo-random Codes

This paper aims to present a digital radio broadcasting system that explores the advantages of pseudo-random codes. In this context, a transmitter and its dual receiver are able to reuse frequency spectrum bands without interfering on other existing communication systems. It is proposed a communication system that allows radio broadcasting with the following characteristics: lower transmission power, new communication channels and digital signal processing techinques to add positioning services in two dimensions.

企业数字化转型对客户集中度的影响

企业数字化转型是中国发展数字经济中的重要一环,在很大程度上推动了数字经济与实体经济实现融合发展,进而使中国在新一轮国际竞争中获得重要优势。采用2011—2021年沪深两市A股上市公司的数据,对数字化转型和客户集中度的关系及其中的渠道机制进行实证检验。研究结果表明,随着企业数字化转型程度的提升,客户集中度会显著降低,在这一过程中,数字化转型会提高企业进行高质量信息披露的能力和动力,从而缓解过于集中的客户资源给企业带来的压力。此外,对于销售费用率和盈余管理程度较高、全要素生产率和分析师关注度较低的企业以及非国有企业来说,进行数字化转型能够更加显著地为企业吸引客源,减少客户集中度。同时,相对于数字经济发展还较为落后的省份,处于数字经济发展水平较高地区的企业,更有可能通过进行数字化转型显著降低对大客户的依赖程度。最后,研究发现数字化转型降低客户集中度后,可以进一步提高企业市场地位。