Strip silicon waveguide for code synchronization in all-optical analog-to-digital conversion based on a lumped time-delay compensation scheme

An all-optical analog-to-digital converter （ADC） based on the nonlinear effect in a silicon waveguide is a promising candidate for overcoming the limitation of electronic devices and is suitable for photonic integration. In this paper, a lumped time-delay compensation scheme with 2-bit quantization resolution is proposed. A strip silicon waveguide is designed and used to compensate for the entire time-delays of the optical pulses after a soliton self-frequency shift （SSFS） module within a wavelength range of 1550 nm-1580 nm. A dispersion coefficient as high as -19800 ps/（km.nm） with ＋0.5 ps/（km.nm） variation is predicted for the strip waveguide. The simulation results show that the maximum supportable sampling rate （MSSR） is 50.45 GSa/s with full width at half maximum （FWHM） variation less than 2.52 ps, along with the 2-bit effective- number-of-bit and Gray code output.

A Digital Background Calibration Technique for Successive Approximation Register Analog-to-Digital Converter

A digital background calibration technique that corrects the capacitor mismatches error is proposed for successive approximation register analog-to-digital converter (SAR ADC). The technique is implemented in SAR ADC which is based on tri-level switching. The termination capacitor in the Digital-to-Analog Converter (DAC) is regarded as a reference capacitor and the digital weights of all other unit capacitors are corrected with respect to the reference capacitor. To make a comparison between the size of the unit capacitor and that of the reference capacitor, each input sample is quantized twice. The unit capacitor being calibrated is swapped with the reference capacitor during the second conversion. The difference between the two conversion results is used to correct the digital weight of the unit capacitor under calibration. The calibration technique with two reference capacitors is presented to reduce the number of parameters to be estimated. Behavior simulation is performed to verify the proposed calibration technique by using a 12-bit SAR ADC with 3% random capacitor mismatch. The simulation results show that the Signal-to-Noise and Distortion Ratio (SNDR) is improved from 57.2 dB to 72.2 dB and the Spurious Free Dynamic Range (SFDR) is improved from 60.0 dB to 85.4 dB.

72 MHz/54 MHz SAMPLING RATE CONVERSION SYSTEM OF HDTV STUDIO SIGNAL

Sampling rate conversion finds great use in the area of multirate signal processing, communications system, speech processing system, etc. In this paper, we describe a structure of 72 MHz/54 MHz sampling rate conversion system which is applied to HDTV system. First, we discuss the theoretical model of a 4/3 conversion scheme and then design the hardware structure implemented in parallel and illustrate the subsystem structure in detail. Finally, the phase diagrams are presented to show the relations between the clocks.

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.

A Flexible and High Speed Digital Scan Converter for High Frequency Ultrasound Imaging

This paper presents a flexible and high speed digital scan converter (DSC) with the ability to handle high frequency ultrasound imaging in real-time. The characteristics in imaging system such as focus length of transducer, the swing radius and sampling length etc. could be changed easily in compliance with the researcher's application based on this flexible digital scan converter. Linear interpolation is employed to achieve the coordinate transformations algorithm. Custom-built software is programmed to preliminarily handle the algorithm according to different ultrasound imaging applications. High performance FPGA will implement high speed interpolation calculation based on the preliminary data which are stored in the DDR2 SDRAM from the software. 64 bit 66 MHz PCI is employed to accomplish high speed data transmission. Experiment has shown that more than 500 frame rate could be achieved based on this high speed digital scan converter. The designed flexible and high speed digital scan converter could be used in current FPGA based high frequency ultrasound imaging system.

基于FPGA的多通道温度采编装置设计

针对飞行试验中对设备温度测量的需求,设计了一种适用于飞行测试的高精度多通道温度采编装置。设计以FPGA构建信号采集处理系统,采用AD8227和AD590来实现信号的调理和温度冷端补偿,通过标准RS422协议实现16路温度信号传输,并采取线性拟合的方式对输出进行非线性校正,提高了系统准确率和稳定性。测试结果表明,测温电路全量程内最大测量误差为±0.083%F.S.。经过测试验证,该方案传输过程无丢帧零误码,系统运行高效、可靠。

基于FPGA的单光子时间数字转换器设计

针对单光子计数器对高速飞行光子时间测量的高分辨率要求,传统的TDC在时间测量上存在误差较大的不足。本文设计了一种利用FPGA内部逻辑延迟单元Carry4级联构建延迟链的TDC。该方法首先使用子链平均的方式进行数据采样,避免数据“气泡”。其次,结合码密度测试和bin-by-bin校准将各级延迟单元宽度校准至接近均匀宽度,提高系统的测量精度。最后,通过Vivado软件仿真并烧录至ZYNQ7000进行板级测试,实验结果表明,该TDC能够在3 ns的动态时间范围内实现时间分辨率10.91 ps,差分非线性(DNL)范围为[-0.75,1.01]LSB,积分非线性(INL)范围为[-1.74,2.19]LSB。

火炮角度参数计量装置关键技术研究与设计

针对现有手段无法满足火炮角度参数对高精度计量的需求,研究提出一种进一步提高火炮角度计量精度的方法,采用正、余弦函数电路及数字—舷角变换电路设计制作了18位高精度数字—舷角转换器,采用D/A转换、电机转速及传动比例换算的方式模拟角度、角速度信号,并制作基于该技术的火炮角度参数计量装置,通过实验验证了该装置的准确性。

职业教育数字化转型视角下专业群建设策略研究

数字化转型正在推动社会全面变革。数字化时代的到来,使职业教育面临数字化转型的机遇和挑战。数字化转型不仅会改变职业教育的教学方式和内容,也对职业教育的专业群建设提出了新的要求。基于职业教育数字化转型的视角,分析数字化转型对职业教育专业群建设的影响,并从专业动态调整、师资队伍建设、在线资源库建设等方面提出专业群建设的有效策略。

Time-stretch analog-to-digital conversion with a photonic crystal fiber

All-optical analog-to-digital conversion (ADC) has been extensively researched to break through the inherently limited operating speed of electronic devices. In this paper, we use the photonic crystal fiber (PCF) for time-stretch (TS) analog-to-digital (A/D) conversion system through generating low noise, linear chirp distribution and flat super-continuum (SC). Based on the radio frequency (RF) analog signal modulated to the linearly chirped super-continuum, the large-dispersion photonic crystal fiber is used for time-domain stretching.

沉浸美学视野下宋画山水的数字化转变

宋画的数字化美学体现在解构与重组中,主要从形式上的二维到三维的转变;叙事上的消解与转换;体验中的五感融合与沉浸这三点体现。本文以宋画中的山水画为主,从宋画与沉浸美学的关系入手,结合案例分析宋画在数字化过程中的转变与呈现,以沉浸美学的视角探究宋画本身可被活化的因素,希望能为其他中国传统绘画数字化提供参考,为文化与技术结合作出有意义的探讨。

一种教学演示用固体密度测量仪设计

为提高学生智能仪器设计水平,提高学生动手能力,该项目设计了一种教学演示用固体密度测量仪。首先,采用压力传感器分别测量吊篮中的固体在空气和浸没水中的重量;然后,通过比较两者的差值计算浮力大小,并采用阿基米德公式计算固体密度。实验证明:该设计测试样品的铝密度均值为2627.8kg/m3,相对误差均值为3.57%,固体密度测量仪测量精度符合设计要求,可在教学中作为智能仪器课程设计的实例使用。

磁阻式旋转变压器解码系统设计

在高性能电机的闭环控制系统中,旋转变压器(简称旋变)常用于测量电机转子的位置与速度信息,设计了一种以专用旋变数字转换芯片为核心的磁阻式旋变解码系统,用于将旋变输出的正余弦信号解码为转子的位置信息。解码系统包括主芯片模块、旋变输入信号调理模块、励磁缓冲电路模块和电源模块等,将各功能模块集成在一块印刷电路板(PCB)上,并通过实验验证了设计方案的有效性。实验结果表明:设计的磁阻式旋变解码系统运行稳定,能实时准确地输出电机转子的位置与速度信息。

客户数字化转型与企业营运资金管理效率——基于竞争侵占与约束防御的双重视角

无论在企业管理实践中,还是从已有文献来看,客户数字化转型对企业营运资金管理效率表现出促进还是抑制,仍未形成一致结论。文章采用中国深沪A股上市企业披露的前五大客户数据,探讨客户数字化转型对企业营运资金管理效率的溢出效应与作用机理。基准检验发现,客户数字化转型降低了企业营运资金管理效率,说明数字溢出存在负外部性。作用渠道检验发现,竞争侵占与约束防御是客户数字化转型影响企业营运资金管理效率的两大渠道,即客户数字化转型催生的数字溢出通过降低企业相对议价能力、降低企业应收账款回收率、加剧企业专用资产套牢风险、加大企业商业信用供给以及扩大企业存货储备规模进而降低了企业营运资金管理效率,说明数字溢出具有竞争约束特征。异质性检验发现,当客户集中度较低、企业规模较大、企业风险承担能力较强时,数字溢出的竞争约束特征得到缓解。研究结论解释了客户数字化转型是否能够提升企业营运资金管理效率的争议,发现了客户数字化转型引致的数字溢出具有竞争约束特征,并提供了企业克服数字溢出负外部性的理论指导,具有理论价值和现实意义。

基于FPGA的高精度振动采集传输系统

为了满足某飞行器飞行过程中不同部位振动监测的需求,完成多路振动信号实时采集,论文提出一种基于FPGA的高精度振动采集传输系统设计方案。首先设计调理电路,将传感器输出的电荷信号调理至采集范围内。其次,使用模拟开关对14路采集通道进行切换,使用16bit高精度ADC实现模数转换。最后,利用FPGA控制整个采集传输过程,将数字量编帧、打包、缓存,并通过以太网接口将采集数据发送至防护存储器进行数据存储。测试表明,数据可靠性高,在单路采样率为20kSPS、测量范围为±2000g时,振动信号的采集精度可达到±0.5%。

转基因定量检测量值转换系数的研究进展

基于PCR技术测定的转基因成分定量结果主要是拷贝数比值,而“产品标识”规定检测结果必须以质量分数表示。量值单位的不统一,造成无法根据检测结果直接进行标识与否的判定。因此亟须研究转基因含量2种单位间的量值关系,建立实现量值转换的“转换系数”定值方法,从而保障检测结果与标识阈值的直接可比。通过对国际转基因“产品标识”制度进行总结,系统分析了影响“转换系数”量值的关键因素和欧盟建立的定值方法,并就我国开展相关研究的重要性进行了论述,为我国转基因“产品标识”制度的有效执行提供参考。

个性数字化辅助椎体成形术单侧穿刺治疗胸腰椎骨质疏松性骨折的疗效分析

目的探讨术前CT个性数字化辅助椎体成形术单侧穿刺治疗胸腰椎骨质疏松性椎体压缩骨折的临床疗效。方法回顾性分析自2020年1月至2023年1月诊治的53例胸腰椎骨质疏松性椎体压缩骨折,28例采用个性数字化设计辅助单侧穿刺PVP治疗(单侧组),25例采用常规双侧PVP治疗(对照组)。比较2组患者手术时间、术中透视次数、骨水泥注入量、骨水泥渗漏率,比较2组术前、术后1 d、术后3个月、末次随访时的疼痛VAS评分、ODI评分以及伤椎Cobb角。结果各组均顺利完成手术。单侧组手术时间、术中透视次数、骨水泥注入量、骨水泥渗漏率较对照组少,差异差异有统计学意义(P<0.05)。2组术前、术后1 d、术后3个月、末次随访时的疼痛VAS评分、ODI评分以及伤椎Cobb角比较,差异无统计学意义(P>0.05)。结论个性数字化辅助单侧穿刺PVP可减少术中透视次数和手术时间,提高穿刺准确性和减少相关并发症,临床疗效满意。

基于环形游标时间数字转换器的编码转换电路

基于应用在锁相环的环形游标时间数字转换器(Vernier ring time-to-digital converter,VRTDC),提出了一种温度计码编码转换电路,解决了VRTDC电路在小量程计数时输出电路无法输出准确的码值,导致时间间隔错误的输出量化问题。采用Cadence Spectre仿真工具在标准180 nm CMOS混合信号工艺下对编码转换电路进行验证,验证结论表明该VRTDC可输出正确的编码值,有效分辨率可达10 ps、动态范围可达560 ns,且在测量范围内具有很好的线性度。

数字化转型升级的内在影响机理实证研究——基于回归分析模型

为深入探究数字化转型、技术创新投入和技术创新产出对数字化转型升级的影响,本文收集2014~2023年477家上市公司作为样本数据,分析数字化转型升级的内在驱动机制。其中,选取数字化转型升级水平为被解释变量,选取数字化转型、技术创新产出、技术创新投入为解释变量,选取企业规模、营运能力、成长能力、企业年龄为控制变量,通过回归分析验证数字化转型升级的内在影响机理,并开展稳健性检验。结果表明,数字化转型、技术创新投入和技术创新产出促进数字化转型升级的提升。根据实证结果得出:要实现数字化转型升级,应进一步加快对数字化资源的投入,同时加强技术创新,加快企业研发产出,从而才能更好地促进产业发展。