Adaptive target and jamming recognition for the pulse doppler radar fuze based on a time-frequency joint feature and an online-updated naive bayesian classifier with minimal risk

This paper considers the problem of target and jamming recognition for the pulse Doppler radar fuze(PDRF).To solve the problem,the matched filter outputs of the PDRF under the action of target and jamming are analyzed.Then,the frequency entropy and peak-to-peak ratio are extracted from the matched filter output of the PDRF,and the time-frequency joint feature is constructed.Based on the time-frequency joint feature,the naive Bayesian classifier(NBC)with minimal risk is established for target and jamming recognition.To improve the adaptability of the proposed method in complex environments,an online update process that adaptively modifies the classifier in the duration of the work of the PDRF is proposed.The experiments show that the PDRF can maintain high recognition accuracy when the signal-to-noise ratio(SNR)decreases and the jamming-to-signal ratio(JSR)increases.Moreover,the applicable analysis shows that he ONBCMR method has low computational complexity and can fully meet the real-time requirements of PDRF.

Study on the method of polarization suppression of cheating jamming in pulse Doppler radar

A jamming suppression method based on polarization signal detection is proposed under common range and velocity cheating jammingfor pulse Doppler radar. On the basis of the separation of the target and the jamming, the range and velocity track on the true target are realized. Firstly the signal processing model of the full polarization pulse Doppler radar is introduced. Secondly the method of correct target separation is discussed, which is the twice detections of energy and polarization state on the two dimension resolution cells of range and velocity of the radar echo. Finally the simulations are performed and the results prove the validity. What's more, multiple range and velocity cheating jamming can be suppressed at the same time if the target and the jamming are different in the polarization domain.

Repeater jamming suppression method for pulse Doppler fuze based on identity recognition and chaotic encryption

Pulse Doppler(PD) fuze is widely used in current battlefield. However, with the threat of repeater jamming, especially digital radio frequency memory technology, the deficiency in the anti-repeater jamming of a traditional PD fuze increasingly emerges. Therefore, a repeater jamming suppression method for a PD fuze based on identity(ID) recognition and chaotic encryption is proposed. Every fuze has its own ID which is encrypted with different chaotic binary sequences in every pulse period of the transmitted signal. The thumbtack-shaped ambiguity function shows a good resolution and distance cutoff characteristic. The ability of anti-repeater jamming is emphatically analyzed, and the results at different signal-to-noise ratio(SNR) show a strong anti-repeater jamming ability and range resolution that the proposed method possesses. Furthermore, the anti-repeater jamming ability is influenced by processing gain, bit error rate(BER) and correlation function. The simulation result validates the theoretical analysis, it shows the proposed method can significantly improve the anti-repeater jamming ability of a PD fuze.

Pulse wave Doppler ultrasound of testicular arteries and their relationship with semen characteristics in healthy bulls

Background: Semen evaluation is used to estimate the testicular function. In bulls, the spermatozoa present in the ejaculate are the result of a process that begun more than 2 mo earlier, bequeathing a delayed depiction of the actual function of the testis. Since testis vascularization might be critical for the gonad function, selected pulse wave Doppler ultrasound parameters were assessed in this study, for instance the peak systolic velocity, the end diastolic velocity and the resistive index of the testicular artery along the spermatic cord, the marginal portion of the testicular artery and the intratesticular branches of the testicular artery both in healthy adult and young bulls.Correlations between these parameters and characteristics of semen that was collected numerous times, before and after the Doppler ultrasound examination.Results: The peak systolic velocity and the end diastolic velocity measured in the testicular artery along the spermatic cord(supratesticular artery – SA) were variable among the bulls and within individual bulls, likely due to the convoluted course of the vessel. The resistive index was found highly repeatable in the same bull. A reduction in the resistive index was found between the supratesticular artery and the marginal portion of the testicular artery(P < 0.01), and between the marginal portion of the testicular artery and the intratesticular branches of the testicular artery(P < 0.05). No differences were recorded for the pulse wave Doppler ultrasound parameters in young bulls compared with adults. A significant correlation was found between the resistive index of the marginal portion of the testicular artery and total sperm in the ejaculate(r = 0.516, P < 0.05), the immature sperm(r = 0.462, P < 0.05), the teratoid sperm(r = 0.375, P < 0.05), and the "Dag defect" sperm(r = 0.389, P < 0.05). Similarly, the resistive index of the intratesticular branches of the testicular artery were found correlated with the total sperm number in the ejaculate(r = 0.568, P < 0.05), the immature sperm(r = 0.523, P < 0.05), the teratoid sperm(r = 0.418, P < 0.05), and the "Dag defect" sperm(r = 0.341, P < 0.05).Conclusions: The data presented in this study suggest that the resistive index, measured at the marginal portion of the testicular artery, could be an easy-to-perform parameter to evaluate the spermatogenesis quality in young bulls and normal adults.

加速器生产^(103)Pd的厚铑靶制备工艺研究

铑靶的制备是加速器生产核素^(103)Pd的关键技术。为制得致密、稳定、厚度高的铑靶,采用改性工艺对硫酸铑溶液进行预处理,并加入一定量电镀添加剂A,得到低应力镀铑液。实验靶片选择金属铜材质,靶片面积约100 mm×10 mm。分别针对电镀过程中的电源电流密度、电镀温度、H_(2)SO_(4)浓度、电镀添加剂A浓度等进行条件实验,获得最佳电镀条件。结果表明,选用最佳电镀条件下,连续四个批次制备的铑镀层质量厚度均大于150 mg/cm^(2),在热冲击实验和坠落实验中,镀层未出现起皮、脱落等问题,镀层致密、平整、与基底结合牢固。在C30回旋加速器内辐照5~51.5 h,可以获得产额5.18~6.04 MBq/(μA·h)、核纯度大于99.9%的^(103)Pd核素。本研究解决了脉冲电镀法制备铑靶工艺稳定性差的问题,制备的厚铑靶可满足^(103)Pd批量化生产要求。

SEVERAL PROBLEMS IN DESIGNING DBS SYSTEMS FOR AIRBORNE PULSE DOPPLER RADAR

ＳＥＶＥＲＡＬＰＲＯＢＬＥＭＳＩＮＤＥＳＩＧＮＩＮＧＤＢＳＳＹＳＴＥＭＳＦＯＲＡＩＲＢＯＲＮＥＰＵＬＳＥＤＯＰＰＬＥＲＲＡＤＡＲＹＡＮＧＪｉａｎｈａｎｇ（杨建航）（ＤｅｐａｒｔｍｅｎｔｏｆＡｅｒｏ－ＥｌｅｃｔｒｏｎｉｃＥｎｇｉｎｅｒｉｎｇ，ＡｉｒＦｏ...

Doppler shift of a laser pulse beam scattered by a rotating cone and cylinder

Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the detected area elements are analyzed by geometric methods. The Doppler shift characteristics of the rotating cone and cylinder are discussed and the difference between the laser pulse beam and the plane wave scattered from the same rotating target is compared accordingly. Numerical simulations show that the Doppler shift is tightly relevant to their dimensions, speeds, and so on. In the same incidence conditions, the pulse beam and plane wave have difference peak values and the same Doppler shift bandwidth. If the waist radius of the pulse beam is larger, the peak value is higher, and the Doppler shifts are proportional to the speed of the rotating target. By virtue of our theoretical model, we probe into the scattered characteristics of the Doppler shifts of a laser pulse beam, which would benefit target identification in national defense.

STUDY OF PULSED DOPPLER SIGNAL PROCESSING AND VELOCITY TRACKING TECHNIQUE

This paper describes a signal processing system in a Pulsed Doppler (PD) radar. It mainly consists of a velocity tracking loop and a digital signal processing auxiliary channel. With many signal processing techniques, the system successfully solves the signal detection and tracking at low SNR and the interference identification and rejection. The idea of system design is introduced in detail. Finally, some simulation and experimental results are presented.

Prevalence of Atrial Fibrillation in Systolic Heart Failure, Pulsed and Tissue Doppler Echocardiographic Abnormalities

Background: Heart failure (HF) is a common clinical syndrome mostly due to the impaired ability of the Left Ventricle (LV) to eject blood with reduced cardiac output. Heart failure is called systolic (SHF) if left ventricle ejection fraction on echo-cardiogram is low (LVEF of ≤50%). Aim: To assess the echocardiographic characteristics of patients with SHF with Atrial Fibrillation (AF) and compare with those with Sinus Rhythm (SR) on 12 leads ECG. Furthermore, to evaluate the clinical and biochemical markers for the prediction of AF in SHF. Method: Over two years duration, each patient diagnosed with SHF was enrolled in the study (n = 354) based on admission code. AF or sinus rhythm on 12 leads ECG was documented on each patient. Multiple logistic regression analysis was applied to assess the risk ratio of different clinical and Doppler derived variables for the development of AF in SHF. Results: Out of the total hospital medical admissions of 14,674 patients, there were 354 patients with diagnosis of SHF, a prevalence of 2.4%. The incidence of AF on ECG was 109 (31%) patients in the whole study population and 245 (69%) in SR. M Mode echocardiogram in patients with SHF and AF compared with those in SR showed significant dilation of LV cavity in systole with LVESD of 5.72 ± 0.63 vs. 5.23 ± 0.76 cm, P < 0.001 and in Diastole LVEDD of 6.83 ± 0.51 vs. 6.58 ± 0.63 cm, P < 0.001. Pulsed Doppler echocardiogram showed a severe restrictive-pattern with shorter Decellration Time (DT) of 163.73 ± 7.42 vs. 214.9 ± 31.81msec, P < 0.001 and higher Pulse to Tissue Doppler ratio of E/Em of 14.26 ± 1.34 vs. 9.99 ± 1.27, P , and the serum level of Brain Natriuretic Peptide (BNP) hormone of 723.72 ± 13.45 vs. 686.98 ± 72.57 pg/ml, P < 0.001. The predictive risks (odd ratio) of different clinical variables for the development of AF in SHF were positive for high BNP > 500 pg/ml of 2.8, history of hypertension of 1.8, history of DM of 1.7, BMI > 28 of 1.4, LV hypertrophy on ECG of 1.3. Conclusions: The prevalence of Systolic Heart Failure in the study population was 2.4%. The prevalence of AF in the study population was 31%. The best predictors of AF in SHF were high BNP > 500 pg/ml, history of hypertension, Diabete Mellitus and LV Hypertrophy on ECG.

QUANTITATIVE ANALYSIS ON CHANGES OF HEPATIC HEMODYNAMICS AFTER TRANSCUTANEOUS ELECTRIC PULSE STIMULATION OF LOCAL POINTS BY USING COLOR DOPPLER ULTRASOUND DIAGNOSTIC APPARATUS

Objective: To evaluate the effect of transcutaneous electric pulse stimulation (TEPS) on hepatic blood flow and parenchymal microcirculation in patients with fatty liver. Methods: A total of 31 fatty liver volunteer patients were observed in this study. Changes of color Doppler energy (CDE) images before and after TEPS of local points nearby the liver were recorded by using color Doppler ultrasound diagnostic apparatus (ACUSON 128XP/10C). Sum of color pixel area (SCPA), average of color value (ACV) and SCPA×ACV (integral) of the hepatic flow images were analyzed by an image processing system, single blind method and paired t-test. Programmed TEPS (0.5- 150 Hz / 2 000 Hz , 10- 25 V ) was applied to the right Qimen (期门 LR 14)-Jingmen (京门 GB 25), Fuai (腹哀 SP 16)-Ganshu (肝俞 BL 18) respectively for 15 min. Results: Compared with basic values of pretreatment, SCPA, ACV and SCPA×ACV increased significantly (t=2.71, P<0.02; t=3.42, P<0.01; and t=8.15, P<0.001) after TEPS, meaning improvement of hepatic blood flow supply. Conclusion: TEPS of acupoints near the liver can improve hepatic blood flow and hepatic parenchymal microcirculation in patients with fatty liver.

Ankle-brachial index and brachial-ankle pulse wave velocity are risk factors for ischemic stroke in patients with type 2 diabetes

The incidence of ischemic stroke in patients with diabetes is increasing. While brachial-ankle pulse wave velocity （BaPWV） and ankle-bra- chial index （ABI） are known to be associated with ischemic cardiovascular and cerebrovascular diseases, whether these measures predict the risk of ischemic cerebrovascular disease in diabetic patients remains unclear. 117 patients with type 2 diabetes were enrolled in this study. According to the results of head magnetic resonance imaging, the patients were divided into a diabetes-only group （n = 55） and a diabetes and ischemic stroke group （n = 62）. We then performed ABI and BaPWV examinations for all patients. Compared with the diabe- tes-only group, we found decreased ABI and increased BaPWV in the diabetes and ischemic stroke group. Multivariate logistic regression analyses revealed that BaPWV and ABI were risk factors for ischemic stroke in patients with type 2 diabetes. Our findings indicate that decreased ABI and increased BaPWV are objective indicators of increased risk of ischemic stroke in patients with type 2 diabetes.

Use of pocket pulse oximeters for detecting peripheral arterial disease in patients with diabetes mellitus

Recent Aims: New diagnostic methods are needed to detect peripheral arterial disease easier than using the ankle-brachial index measured by Doppler devices. We investigated whether the use of pocket pulse oximeters could meet sensitivity and specificity criteria as screening method to detect significant peripheral arterial perfusion deficits. Methods: We measured oxygen saturation (SaO2) at index fingers and great toes (on horizontal and elevated 30°) by a pocket pulse oximeter in 250 subjects with diabetes mellitus attending the outpatient clinic. A finger-to-toe SaO2 gradient greater than 2% was considered abnormal. Ankle-brachial index was measured by a hand held Doppler device. Peripheral arterial disease was defined as an ankle-brachial index less than 0.9. Results: A total of 1392 (93%) valid SaO2 readings were obtained. Twenty-seven (11%) patients were excluded due to not having measurable SaO2 finger-to-toe gradients. A total of 223 patients were analyzed. Peripheral arterial disease was detected in 47 (21%) patients. A finger-to-toe SaO2 gradient greater than 2% had sensitivity 42.6% (95% CI 30.0% - 55.3%), specificity 79.1% (95% CI 75.7% - 82.6%), positive predictive value 35.7% (95% CI 25.2% - 46.4%), negative predictive value 83.4% (95% CI 79.8 - 87.1), positive likelihood ratio 2.03 (95% CI 1.23 - 3.17) and negative likelihood ratio 0.73 (95% CI 0.54 - 0.93) to detect peripheral arterial disease. The area under the receiving operating characteristic curve was 0.69 (95% CI 0.62 - 0.77). Conclusion: Pocket pulse oximeters showed insufficient sensitivity as screening method for detecting peripheral arterial disease in patients with diabetes mellitus.

Simultaneous range and radial velocity estimation with a single narrowband LFM pulse

The mismatch effect induced by the radial motion of a target is analyzed for linear frequency modulated （LFM） signals. Then, a novel integrated processing scheme is proposed to re- solve the delay-Doppler coupling effect in LFM pulse compression. Therefore the range and radial velocity of the target can be si- multaneously estimated with a narrowband LFM pulse. Finally, numerical simulation results demonstrate the effectiveness and good performance of the proposed method.

Simulation and experiment of the cooling effect of trapped ion by pulsed laser

We investigate the process of pulsed laser cooling using a self-constructed molecular dynamics simulation(MDSimulation)program.We simulate the Doppler cooling process and pulsed laser Doppler cooling process of a single^(40)Ca^(+)ion,and the comparison with the experimental results shows that this self-constructed MD-Simulation program works well in the weak laser intensity situation.Furthermore,we analyze the pulsed laser Doppler cooling process of a single^(27)Al^(+)ion.This program can be used to analyze the molecular dynamic process of various situations of Doppler cooling in an ion trap,which could give predictions and experimental guidance.

PULSE CUMULATING METHOD FOR MULTI-TARGETS' JOINT AZIMUTH-ELEVATION FREQUENCY-DELAY ESTIMATION

The Directions of Arrivals （DOAs）, speeds and distances of targets are all required for array signal processing. Based on the periodic phase shift of coherent pulse sequence waveform, a new estimation of multi-targets＇ 2-Dimentional （2-D） DOA angle, Doppler frequency shift and relative time-delay is proposed. Based on a virtual sensor array constructed by pulse cumulating, the estinaations of azimuth, elevation, Doppler frequency shift and time-delay can be obtained simultaneously, and the least number of pulses could be two. This method is computationally efficient even in heavier noised environment, and all estimations are automatically paired in calculation process with no used to any plane sensor array and deal with many spectrum searching. Further more, this algorithm can be targets at the same time only by few sensors. The targets number that can deal with simultaneously is several times to the sensor number, which is the upper limit for normal algorithms such as ESPRIT and MUSIC. These characteristics would be very useful, especially, for aerial systems. Simulations demonstrate the capabilities of this method efficiently.

基于二相码的PD雷达解模糊及遮挡方法

为避免二相编码脉冲多普勒(pulse Doppler,PD)雷达的速度以及距离模糊,采用高脉冲重复频率工作(high pulse repetition frequency,HPRF)模式,并在多个脉冲间采用互相关峰值较低的二相编码信号,在接收端对多个发射脉冲间的回波信号进行数据重排,然后进行脉冲压缩、动目标检测,最终得到的峰值可无模糊体现目标的速度和距离。为减小PD雷达的工作盲区,采用了小的发射脉冲时间宽度,即二相编码信号的码片长度;为避免PD雷达的发射脉冲遮挡,采用两种HPRF发射正交二相编码脉冲信号。仿真结果验证了所提方法的有效性和可行性。

基于遗传算法的机载中重频高效多维优化

机载脉冲多普勒(PD)雷达的重频组设计是雷达总体设计的基础,直接影响雷达的性能和应用场景。在中重频组设计过程中,必须考虑多维度参数的优化,由于可调整参数多,会导致潜在组合数膨胀严重,对计算资源和时间提出了极大的挑战。传统的优化方法,即便在限定参数范围后,仍面临穷举组合数庞大的问题。此外,机载雷达系统设计周期通常较短,模式需求多变,需要在较短时间内完成方案前期参数的选择和初步优化,便于开展后续设计。本文提出了一种基于遗传算法的高效多维优化方法,不仅增加了优化维度以更好满足工程需求,同时显著提升了优化效率。通过应用实例验证了所提方法的有效性,对机载PD雷达总体设计论证具有重要价值。

基于多频脉冲采样的血流速度估计方法

传统双模超声技术相较于新兴技术更具实现可穿戴化的潜力。在进行脉冲多普勒血流速度估计时,双模超声需同时发射B模式脉冲进行成像定位,这要求B模式脉冲和多普勒脉冲共享采样时间。采用基于单频多普勒脉冲的稀疏间隔发射方式可以解决这一问题,但常见的稀疏发射排布方式(如嵌套发射、互质发射等)存在采样时间窗较长的缺点,特别是在血流速度变化明显的情况下存在时间分辨率不足的问题。此外,长时间窗包含了较多的血流速度分量,容易由于稀疏采样引起伪影,从而影响血流速度估计的准确性。因此,文中提出了一种基于多频脉冲采样的新型血流速度估计方法。首先,构建了多频脉冲采样的回波模型,并对该模型进行推导,证明了在频率衰减平稳假设下,该数学模型等价于单频多普勒脉冲稀疏发射方式,即多频脉冲采样可以通过较短的时间窗实现类似于基于单频脉冲采样模式的长时间窗的性能,从而提高血流速度谱的时间分辨率和估计精度;然后,提出了两种可用于多频脉冲采样模式的血流速度谱的构建方法,分别为复杂度较低的BMUSIC算法和伪影抑制效果较佳的VMUSIC算法。基于FieldⅡ仿真数据和人体实测数据的实验结果表明:相较于单频多普勒脉冲稀疏发射方式,文中方法不仅可以采用较短的时间窗提升血流速度谱的时间分辨率,还可以获得连续、清晰、精度较高且伪影抑制效果较佳的血流速度估计结果;在人体实测数据实验中,由于实验条件所限,文中方法无法实现非整数倍频,未能充分展现VMUSIC算法的性能优势。

方位向调制干扰对高分宽幅多通道SAR的影响

多通道合成孔径雷达(synthetic aperture radar,SAR)能够利用方位向多通道重构处理去除多普勒模糊,获得高分宽幅SAR图像。针对此特殊的多通道重构处理方式,研究了传统SAR方位向调制干扰对高分宽幅多通道SAR的影响,包括多普勒调制干扰和脉冲延迟转发干扰两种类型的方位向调制干扰方式,为高分宽幅多通道SAR干扰决策提供理论基础。理论分析指出,多普勒调制干扰信号经成像处理后将在方位向生成等间隔分布的虚假目标,并且幅度受与多普勒调制频率相关的正弦函数和匹配滤波损失联合调制;而脉冲延迟转发干扰信号在成像后将只有单个干扰目标出现,且目标的方位位置仅与延迟的脉冲数有关。仿真实验验证了理论分析的正确性。

一种基于脉冲方位的多普勒解要素方法

舰船发射的主动声呐脉冲信号声源级高,频带窄,信噪比高,利用这些特点,可以比较精确地测量声呐脉冲信号的方位和频率信息从而有利于目标运动要素解算。本文针对发射主动脉冲的水下目标,提出一种基于主动声呐脉冲方位的多普勒解要素方法,首先估计主动脉冲信号时间位置及频率,在此基础上利用非线性回归的方法,将每一个脉冲的时刻、方位、频率以及本平台相应时刻的速度和位置等要素组成的多维向量,视作样本空间中的一个点,根据各要素间的函数关系,进行非线性拟合,从而获得目标运动要素的估计值。实测数据验证表明,提出的频率估计方法精度满足目标运动分析的要求;仿真验证了基于非线性回归的脉冲方位-频率目标运动分析算法整体的有效性。