基于FPGA 超声信号数字动态滤波器的实现

目的:本文研究了基于现场可编程门阵列(Field Programmable Gate Array,FPGA)超声成像系统中数字动态滤波器的实现方法和过程。方法:动态滤波器中FIR滤波器采用分布式算法(Distributed Arithmetic,DA)实现结构,并在应用中对DA算法进行了改进,包括数据并行处理结构的设计、对查找表(Look Up Table,LUT)输入字长N大小的控制和具有对称系数的FIR滤波器的采用。改进后的DA实现在FPGA资源占用和处理速度之间达到了平衡。同时,结合多级流水线结构,动态滤波器实现了数字超声信号并行处理。结果:采用常值滤波器(远场匹配参数)进行滤波后,超声回波图像远场分辨率达到了要求,但越靠近近场效果越差。相比之下,本文设计的基于FPGA超声信号动态数字滤波器达到了很好的滤波效果,使回声图像近场和远场都有最佳分辨率。结论:利用FPGA实现超声系统中动态滤波器是完全可行的,并且有助于提高系统的稳定性和可靠性,并大大减低系统成本。     

基于SOPC技术的多路并行ECG实时检测分析系统的设计

针对目前心电监护设备微型化、实时性、高采样率、存储量大等实际需求,采用了一种基于最新的SOPC（System On a Programmable Chip）技术的心电检测系统的设计。将DSP和MCU的功能集成在一块FPGA上,在FPGA内部实现多路心电信号的并行处理,由SD卡记录较长时间的连续心电信号,并实现心电信号的实时分析和心律失常的预警等扩展功能。     

FPGA技术在生物医学成像中的研究进展

数字图像处理技术和微电子集成电路的飞速发展,使实时动态生物医学成像成为可能.生物医学动态成像的关键是高的通讯带宽和快速的数据处理能力,FPGA (field programmable gate array)即现场可编程逻辑门阵列,为数字图像实时处理系统在算法、系统结构上提供了新的思路与方法.文中首先简单介绍FPGA的概念、特点及其发展历程,详细对比FPGA与通用处理器之间的性能指标,然后重点介绍常规生物医疗成像技术原理和FPGA在医疗领域高速成像技术方面的研究和应用情况,最后对FPGA在实时成像方面进行总结和展望.     

High-performance hardware implementation of a parallel database search engine for real-time peptide mass fingerprinting

Motivation: Peptide mass fingerprinting (PMF) is a method for protein identification in which a protein is fragmented by a defined cleavage protocol (usually proteolysis with trypsin), and the masses of these products constitute a 'fingerprint' that can be searched against theoretical fingerprints of all known proteins. In the first stage of PMF, the raw mass spectrometric data are processed to generate a peptide mass list. In the second stage this protein fingerprint is used to search a database of known proteins for the best protein match. Although current software solutions can typically deliver a match in a relatively short time, a system that can find a match in real time could change the way in which PMF is deployed and presented. In a paper published earlier we presented a hardware design of a raw mass spectra processor that, when implemented in Field Programmable Gate Array (FPGA) hardware, achieves almost 170-fold speed gain relative to a conventional software implementation running on a dual processor server. In this article we present a complementary hardware realization of a parallel database search engine that, when running on a Xilinx Virtex 2 FPGA at 100 MHz, delivers 1800-fold speed-up compared with an equivalent C software routine, running on a 3.06 GHz Xeon workstation. The inherent scalability of the design means that processing speed can be multiplied by deploying the design on multiple FPGAs. The database search processor and the mass spectra processor, running on a reconfigurable computing platform, provide a complete real-time PMF protein identification solution.     

Endovenous laser treatment of the great saphenous vein: Measurement of the pullback speed of the fiber by magnetic tracking

Endovenous laser treatment (ELT) is a minimally invasive technique used to treat varicose veins. In this technique, an optical fiber is inserted into the vein to be treated and the laser lights while the optical is slowly withdrawn. The average linear endovenous energy density (LEED) delivered during the procedure is determinant in the success of this therapy. Recanalization and side effects are energy-dependent. Thus, the success of the therapy is mainly related to the pullback speed of the fiber. Ideally this speed has to be 1 mm/s. The purpose of this investigation was to evaluate in real time the fiber pullback speed. In order to measure in real time the motion of the fiber inside the saphenous vein, magnetic tracking was used. The system was evaluated during the treatment procedures for 18 patients. The mean pullback speed was 1.02 ± 0.15 mm/s similar to the speed the physician wanted to obtain. Based on quality control, safety standards, and regulations official documents for medical lasers, where a 20% accuracy is admitted; only one patient was treated with an average pullback speed inferior to 0.8 mm/s (0.77 cm/s) and two patients were treated with an average pullback speed superior to 1.2 mm/s (1.26 mm/s and 1.32 mm/s). Consequently, even for a well-trained physician, variations can be observed. These variations could easily explain why complications (too low speed and consequently too high LEED) or recurrences (too fast speed and consequently too low LEED) are sometimes reported in clinical studies. A standardized or an automatic withdrawal of the fiber could possibly improve this technique but remains to be carefully evaluated.     

Particle Size, Moisture, and Fluidization Variations Described by Indirect In-line Physical Measurements of Fluid Bed Granulation

The aim of this study was to evaluate an instrumentation system for a bench scale fluid bed granulator to determine the parameters expressing the changing conditions during the spraying phase of a fluid bed process. The study focused mainly on four in-line measurements (dependent variables): fluidization parameter (calculated by inlet air flow rate and rotor speed), pressure difference over the upper filters, pressure difference over the granules (lower filter), and temperature of the fluidizing mass. In-line particle size measured by the spatial filtering technique was an essential predictor variable. Other physical process measurements of the automated granulation system, 25 direct and 12 derived parameters, were also utilized for multivariate modeling. The correlation and partial least squares analyses revealed significant relationships between various process parameters highlighting the particle size, moisture, and fluidization effect. Fluidization parameter and pressure difference over upper filters were found to correlate with in-line particle size and therefore could be used as estimates of particle size during granulation. The pressure difference over the granules and the temperature of the fluidizing mass expressed the moisture conditions of wet granulation. The instrumentation system evaluated here is an invaluable aid to gaining more control for fluid bed processing to obtain repeatable granules for further processing.     

Magnetic aqueous two-phase separation in preparative applications.

Magnetic aqueous two-phase separation is a new technique to speed up the separation of aqueous two-phase systems (Anal. Biochem. 1987, 167, 331-339). It is based on the addition of magnetically susceptible material (e.g. 1-micron iron oxide particles) which induces rapid phase separation when a mixed system is placed in a magnetic field. The technique has been applied to a number of two-phase systems. The time for phase separation was decreased by a factor of 5-240,000, with the largest improvement for systems containing high concentrations of protein and for systems with viscous or nearly isopycnic phases. An apparatus for preparative multistage extraction with magnetic separation was constructed and tested on glycolytic enzymes present in a yeast extract using a dextran/Cibacron blue-polyethylene glycol system. The presence of iron oxide particles did not adversely affect the extracted enzymes. An electromagnet-based apparatus for continuous phase separation on a larger scale was also designed. A phase system containing crude dextran and unpurified cell homogenate was effectively processed. The apparatus also allowed effective separation when the phase containing iron oxide particles was only a small fraction (4%) of the total phase system.     

土壤微生物的分离、提取与纯化研究进展

综合评述了土壤微生物提取与纯化研究的最新进展及存在的主要问题。土壤微生物的分离提取过程一般分为土壤分散、提取与纯化3个步骤。采用过滤、离心和淘选3种方法可以成功地分离提取大部分土壤细菌;但土壤真菌的提取则相对较为困难,目前可采用的方法有旋转框技术、液相提取与滤膜检测、以及低速离心技术,这些方法可提取出部分真菌菌丝。两相分离技术可用以提取的土壤微生物进行纯化。     

Magnetic aqueous two-phase separation: a new technique to increase rate of phase-separation, using dextran-ferrofluid or larger iron oxide particles

A new technique to speed up the phase separation of aqueous two-phase systems is described. The technique is based on the addition of magnetically susceptible additives (ferrofluids or iron oxide particles). In a magnetic field such additives will induce a faster phase separation. In one approach, dextran-stabilized ferrofluid was added to an aqueous two-phase system containing polyethylene glycol and dextran. The ferrofluid was totally partitioned to the dextran phase. After mixing of the two-phase system, it was possible to reduce the separation time by a factor of 35 by applying a magnetic field to the system. Another approach involved the use of 1-micron iron oxide particles instead of ferrofluid. In this case also, the phase-separation time was reduced, by a factor of about 70, when the system was placed in a magnetic field. The addition of ferrofluid and/or iron oxide particles was shown to have no influence on enzyme partitioning or on enzyme activity. The partitioning of chloroplasts, on the other hand, was influenced unless the ferrofluid used had been treated with epoxysilane. A column system comprising 15 magnetic separation stages was constructed and was used for semicontinuous separation of enzyme mixtures.     

活体动物全细胞记录技术及其应用

活体动物全细胞记录技术不仅可以用于研究感觉系统对自然刺激（如视觉系统的光刺激、听觉系统的声音刺激等）反应的特性和规律,还可以较准确地记录细胞的突触电位（包括阈下反应）,实现EPSP和IPSP的相对分离,并实现活体细胞内灌流,从而进一步研究感觉信息的处理机制。本文较为详细地介绍了在活体动物上进行全细胞记录的方法,包括一些技术细节和关键仪器设备的选取原则,举例说明了该技术在视觉系统研究和体感系统研究中的应用,并讨论了这一方法在神经科学中的应用前景。     

Implementation of a field programmable gate array based transcranial Doppler ultrasound system using pulse compression techniques

A field programmable gate array (FPGA) based hardware platform that is used to implement a digital, multi-gate pulsed Doppler ultrasound system for transcranial Doppler (TCD) use is described. The Doppler audio signal is extracted from the digitised radio-frequency signal by matched filtering and suitable sampling. The system was configured to acquire Doppler signals from 16 depth locations and to display Doppler signal power versus depth as well as a sonogram from a user specified depth. The signal-to-noise performance of the system was comparable with that of a commercially available TCD unit for equivalent pulse repetition frequency and sample volume settings.The flexibility of the platform was used to demonstrate the feasibility of using coded transducer excitation and pulse compression techniques to improve axial resolution compared to a non-coded implementation. The axial resolution improvement was demonstrated using a flow phantom and measured using a vibrating wire phantom. The measured resolutions were 9.1 and 2.4 mm for the conventional and coded implementations, respectively. The reduction in signal-to-noise ratio of approximately 5 dB associated with the configuration using coded excitation was attributable to the frequency response characteristics of the transducer rather than the processing technique used. This work demonstrates both the flexibility associated with an FPGA implementation of a Doppler ultrasound system and the potential for coded excitation to improve axial resolution in TCD systems.     

Mobile image sensors for object detection using color segmentation

The intelligent mobile robot with sensors and image processing embedded system combines the suction and aerodynamic attraction to achieve good balance between strong adhesion force and high mobility. Experimental results showed that the robot can move upward on the wall at the speed of 2.9 m/min and carry 5 kg payload in addition to 2.5 kg self-weight, which record the highest payload capacity among climbing robots of similar size. It also implements object detection ability using effective color transform and segmentation technique for the exact target detection on the wall using a embedded camera system, communication module and several active sensors.     

Two Speed Factors of Visual Recognition Independently Correlated with Fluid Intelligence

Growing evidence indicates a moderate but significant relationship between processing speed in visuo-cognitive tasks and general intelligence. On the other hand, findings from neuroscience proposed that the primate visual system consists of two major pathways, the ventral pathway for objects recognition and the dorsal pathway for spatial processing and attentive analysis. Previous studies seeking for visuo-cognitive factors of human intelligence indicated a significant correlation between fluid intelligence and the inspection time (IT), an index for a speed of object recognition performed in the ventral pathway. We thus presently examined a possibility that neural processing speed in the dorsal pathway also represented a factor of intelligence. Specifically, we used the mental rotation (MR) task, a popular psychometric measure for mental speed of spatial processing in the dorsal pathway. We found that the speed of MR was significantly correlated with intelligence scores, while it had no correlation with one’s IT (recognition speed of visual objects). Our results support the new possibility that intelligence could be explained by two types of mental speed, one related to object recognition (IT) and another for manipulation of mental images (MR).     

基于直线电机的大视场快速光声显微成像系统

光声成像技术是近年来发展的一种新型的无损医学成像技术,它是以脉冲激光作为激发源,以检测的声信号为信息载体,通过相应的图像重建算法重建组织内部结构和功能信息的成像方法。该方法结合了光学成像和声学成像的特点,可提供深层组织高分辨率和高对比度的组织层析图像,在生物医学临床诊断以及在体成像领域具有广泛的应用前景。目前光声成像的扫描方式主要有基于步进电机扫描方式和基于振镜的扫描方式,本文针对目前步进电机扫描速度慢(10 mm×10 mm;0.001帧/s),振镜扫描范围小(1 mm2)的不足,发展了基于直线电机扫描的大视场快速光声显微成像系统。同一条扫描线过程中直线电机速度最高可达200 mm/s。该技术采用逐线采集光声信号的方式,比逐点采集光声信号的步进电机快800倍。该系统对10 mm×10 mm全场扫描的扫描速度为0.8帧/s。最大可扫描视场范围可以达到50 mm×50 mm。大视场快速光声显微成像系统的发展将为生物医学提供新的成像工具。     

An FPGA hardware/software co-design towards evolvable spiking neural networks for robotics application

This paper presents an approach that permits the effective hardware realization of a novel Evolvable Spiking Neural Network (ESNN) paradigm on Field Programmable Gate Arrays (FPGAs). The ESNN possesses a hybrid learning algorithm that consists of a Spike Timing Dependent Plasticity (STDP) mechanism fused with a Genetic Algorithm (GA). The design and implementation direction utilizes the latest advancements in FPGA technology to provide a partitioned hardware/software co-design solution. The approach achieves the maximum FPGA flexibility obtainable for the ESNN paradigm. The algorithm was applied as an embedded intelligent system robotic controller to solve an autonomous navigation and obstacle avoidance problem.     

A 15.6 frames per second 1‐megapixel multiple exposure laser speckle contrast imaging setup

A multiple exposure laser speckle contrast imaging (MELSCI) setup for visualizing blood perfusion was developed using a field programmable gate array (FPGA), connected to a 1000 frames per second (fps) 1‐megapixel camera sensor. Multiple exposure time images at 1, 2, 4, 8, 16, 32 and 64 milliseconds were calculated by cumulative summation of 64 consecutive snapshot images. The local contrast was calculated for all exposure times using regions of 4 × 4 pixels. Averaging of multiple contrast images from the 64‐millisecond acquisition was done to improve the signal‐to‐noise ratio. The results show that with an effective implementation of the algorithm on an FPGA, contrast images at all exposure times can be calculated in only 28 milliseconds. The algorithm was applied to data recorded during a 5 minutes finger occlusion. Expected contrast changes were found during occlusion and the following hyperemia in the occluded finger, while unprovoked fingers showed constant contrast during the experiment. The developed setup is capable of massive data processing on an FPGA that enables processing of MELSCI data in 15.6 fps (1000/64 milliseconds). It also leads to improved frame rates, enhanced image quality and enables the calculation of improved microcirculatory perfusion estimates compared to single exposure time systems.      

A quantitative method for the analysis of cell shape and locomotion

A rapid, semiautomated system to quantitate and analyze leukocyte shape and locomotion was developed. Video images of moving leukocytes were obtained using a Vidicon camera mounted on a Nikon phase microscope. The video signal was either inputted directly, or indirectly via a video cassette recorder, to a Datacube video analog-digital, digital-analog converter. A Digital Equipment Corporation LSI 11/23 computer using the RT-11/TSX-Plus operating system and computer programs written in FORTRAN and MARCO assembly language permitted image segmentation, image display, and calculation of position, speed, direction of movement and orientation of each leukocyte at 10 s intervals. These data were stored on a winchester disk for subsequent evaluation of the leukocyte orientation, speed and direction of movement using statistical and graphical methods. The reproducibility of measurements made with the video system was tested by comparison with manual measurements; a correlation coefficient of 0.998 was obtained for the two methods. Rates of chemokinesis were then determined for unstimulated and chemokinetically stimulated polymorphonuclear leukocytes (PMNs) and found to average 12.8 micron/min and 18.1 micron/min, respectively. The high speed, ease of data analysis, and potential for multiparameter evaluation makes this system useful for directly evaluating leukocyte locomotion.     

An autocorrelation model of bat sonar

Their sonar system allows echolocating bats to navigate with high skill through a complex, three- dimensional environment at high speed and low light. The auditory analysis of the echoes of their ultrasonic sounds requires a detailed comparison of the emission and echoes. Here an auditory model of bat sonar is introduced and evaluated against a set of psychophysical phantom-target, echo-acoustic experiments. The model consists of a relatively detailed simulation of auditory peripheral processing in the bat, Phyllostomus discolor, followed by a functional module consisting of a strobed, normalised, autocorrelation in each frequency channel. The model output is accumulated in a sonar image buffer. The model evaluation is based on the comparison of the image-buffer contents generated in individually simulated psychophysical trials. The model provides reasonably good predictions for both temporal and spectral behavioural sonar processing in terms of sonar delay-, roughness, and phase sensitivity and in terms of sensitivity to the temporal separations in two-front targets and the classification of spectrally divergent phantom targets.     

Swimming speed distributions of bull spermatozoa as determined by quasi-elastic light scattering.

88 semen samples from 39 bulls have been investigated by the quasi-elastic light scattering technique. Normal, defective, and dead cells each yielded characteristic autocorrelation functions. The form of these functions indicates that the swimming speed distribution of normal cells is a gamma distribution with two degrees of freedom while that for defective or circular swimmers is a gamma distribution with one degree of freedom. The resulting analysis of the experimental autocorrelation functions yields the fraction of the sample that is normal, the fraction that is defective, and the average speed of each group. The average helical swimming speed of normal cells was found to be 384 micron/s, while the average trajectory speed of the circular swimmers was found to be 103 micron/s. The overall quality of the semen samples as determined by light scattering is compared to quality determination on the same samples by technicians from the artificial insemination industry.     

Hardware acceleration of processing of mass spectrometric data for proteomics

MOTIVATION: High-resolution mass spectrometers generate large data files that are complex, noisy and require extensive processing to extract the optimal data from raw spectra. This processing is readily achieved in software and is often embedded in manufacturers' instrument control and data processing environments. However, the speed of this data processing is such that it is usually performed off-line, post data acquisition. We have been exploring strategies that would allow real-time advanced processing of mass spectrometric data, making use of the reconfigurable computing paradigm, which exploits the flexibility and versatility of Field Programmable Gate Arrays (FPGAs). This approach has emerged as a powerful solution for speeding up time-critical algorithms. We describe here a reconfigurable computing solution for processing raw mass spectrometric data generated by MALDI-ToF instruments. The hardware-implemented algorithms for de-noising, baseline correction, peak identification and deisotoping, running on a Xilinx Virtex 2 FPGA at 180 MHz, generate a mass fingerprint over 100 times faster than an equivalent algorithm written in C, running on a Dual 3 GHz Xeon workstation.