基于多超声波传感器的自主移动机器人探测系统

超声波传感器在自主式移动机器人领域有着广泛的应用。本研究根据自主式移动机器人对实时探测未知环境的要求以及超声波传感器的特点 ,设计并实现了一种适用于自主式移动机器人的声纳环探测系统。首先 ,采用了多超声波分组循环发射的方法 ,极大地降低了多超声波传感器之间的回波干扰 ;然后在对原始数据进行初步处理的基础上 ,给出了多种距离信息表示形式 ;

多超声波传感器的工作空间识别

将超声波传感器应用于煤矿井下机器人的工作空间识别问题 ,研究了应用 DS( Dempster-Shafer)证据理论对超声波传感器信息进行融合的方法 ,包括测量系统的信度分配、证据的提取及动态融合算法等 .最后 ,构造了一个假想的三维工作空间 ,将机器人手臂近似为理想直线段杆件联合体 ,进行了仿真实验 ,取得了满意的仿真结果 .研究表明 ,DS证据理论不但可以合理地表示完全未知的情况 ,还能表示非特定性的信息 ,且具有实用上的简单性 .

多超声波传感器的轮式机器人避障系统研究

移动机器人是能够在一定工作环境中完成预定任务并自主移动的一种智能系统。近年来，随着计算机、微电子、人工智能、网络通信、传感器等技术的发展．对移动机器人的研究逐渐成为了一门多学科交叉研究课题，在民用、军事、工业以及农业等多领域中具有广泛的应用前景。在移动机器人的研究和应用中．避障是最基本也是最重要的问题．机器人必须在其作业过程中具备灵敏可靠的自主避障能力，因此对移动机器人避障系统的研究具有重大的意义。

基于多超声波传感器的移动机器人目标识别

移动机器人在不确定环境中的目标识别技术是自主导航及复杂任务分解的一项关键技术。本文利用自行设计的多超声波传感器探测系统感知外界环境,提出了基于目标原型的目标识别和对感兴趣目标的主动探测方法。根据多超声波传感器的TOF(Time-of-Flight)信息,利用Dempster-Shafer证据理论,实现了移动机器人对室内特征环境的准确识别。测试结果及分析验证了该方法的可行性和识别准确性,并且该方法适用于室内机器人运动中的实时探测。

超声波传感器环系统设计

在自主移动机器人的避障导航中,精确实时探测周围环境信息传感系统至关重要。提出一种基于89s52单片机,多超声波的环境探测器,通过CAN总线,用SDS协议与其他模块通讯,采用分组循环启动的方法大大降低了超声波之间的串扰问题.并对传感器环进行了标定,标定结果证明该传感器环具有较高的精度和较好稳定性。

基于超声波和无线控制自主导航系统研究与设计

智能机器人能够在未知的环境中,根据采集的环境信息或者目标发出的导航信息,确定目标的方向并计算到目标的最优路径。进行全局的路径规划则是实现自主导航的关键技术。在本系统中使用多超声波信息融合技术,探测车载系统周围的环境信息,使用嵌入式处理器ARM7作为系统核心,对采集的信息进行处理,实现避障功能;利用ZigBee无线控制模块,实现PC机对车载系统的导航控制。在全局的路径规划过程中,以蚁群算法为核心,并根据人工势场算法的思想对其进行改进,避免造成局部最优解。测试结果中,证明了系统设计的可行性和合理性。

基于超声阵列的输送带动态煤量检测系统

输送带动态煤量检测是实现顺煤流启动和自动调速等多级带式输送机能耗优化措施的基础和关键。针对现有基于超声波的煤量检测方法精度较低、多超声波传感器之间易受干扰等问题,设计了基于超声阵列的输送带动态煤量检测系统。利用超声波测距原理,通过超声阵列实时检测各超声波传感器阵元对应检测点的煤料高度,采用横截面切片法计算单位时间内输送带上通过煤料的总体积,结合煤料堆积密度计算输送带实时煤流量及总煤量。为降低同频声波串扰及超声波在井下恶劣环境中衰减带来的误差,选用10路中心频率不同的超声波传感器阵元,布置为2×5线性阵列形式,通过多行超声波传感器对采集的煤高数据进行补偿,以提高煤高数据检测准确性。实时性分析结果表明,超声阵列检测速度在理论上满足带速为5 m/s的带式输送机煤量检测要求。实验结果表明:在0.125,0.170 m/s带速下,规则物料体积检测的平均相对误差分别为4.99%,5.16%;模拟实际工况条件下,煤量检测的平均相对误差为5.56%。在低带速状态下,该系统对规则物料和煤料的测量准确度达94%以上,基本实现了输送带动态煤量实时准确检测,满足带式输送机煤量检测需求。

BP多传感器融合技术在罐车油位误差处理中的应用

在油罐车油位测量中,超声波传感器受本身结构和外界温度等因素的干扰,其输入输出特性呈明显的非线性,仅靠硬件补偿的方法来提高精度,效果不明显.采用BP多传感器融合来实现多超声波传感器的非线性误差校正,大大提高了超声波测距精度.另外,BP网络模型很好的泛化能力,简单的网络结构,简明的算法,使其在测控系统及智能传感器中具有良好的应用前景和推广价值.

移动机器人漫游避障的研究

移动机器人在做漫游运动时,它的运动是随机的,因而避障是漫游过程中必须要解决的问题。本文应用多超声波传感器设计了移动机器人漫游避障的控制算法,在Pioneer 3-Dx型移动机器人自带的仿真平台SRIsim上进行了仿真实验,仿真结果表明了所设计算法的有效性和可行性。

基于支持向量机的移动机器人环境识别

针对未知环境下移动机器人的环境理解与识别问题,提出了一种支持向量机(SVM)的环境识别算法。在对移动机器人室内外特征环境分析和建模的基础上,通过机器人配置的多超声波传感器获取环境的距离信息,直接作为环境的特征,按照从左到右的顺序组成表征环境轮廓的六维特征向量,送入支持向量机训练并用于特征环境的识别。克服了多超声波传感器测量数据的不确定性对分类结果准确度的影响,实现了移动机器人对室内外特征环境的正确识别。仿真和实验验证了方法的可行性,与传统的分类算法相比,算法对环境具有更高的识别正确率,在训练样本较少的情况下,能够在不同的位置和角度准确测量识别多类特征环境,具有一定的实用价值。

Optimal Ultrasonic Extraction of Pachyman from Jiuzihe Poria cocos

This study was conducted to extract pachyman to the greatest degree with ultrasonic technology, and to determine the content of pachyman by the phe-nol-sulfuric acid method, so as to choose the optimal technique of ultrasonic extrac-tion of pachyman. Firstly, the ultrasonic power, extraction time and solid-to-liquid ra-tio were investigated by ultrasonic extraction method. Then, on this basis, a respon-sible surface experiment was designed, to select the optimal process conditions ac-cording to the index of pachyman yield. The optimized ultrasonic water extraction conditions were as fol ow： ultrasonic power of 100 W, extraction time of 30 min, and solid-to-liquid ratio at 1：40. The Oxford cup method was used to study the an-timicrobial activity of pachyman. lt was found that pachyman could significantly in-hibit Bacilus subtilis_and Staphylococcus aureus.

Postoperative complications in patients with portal vein thrombosis after liver transplantation:Evaluation with Doppler ultrasonography

AIM： To study the postoperative complications in patients with preoperative portal vein thrombosis （PVT） undergoing liver transplantation （LT） and to evaluate the complications with Doppler ultrasonography.METHODS： Retrospective studies were performed on 284 patients undergoing LT （286 LT） with respect to pre- and postoperative clinical data and Doppler ultrasonography. According to the presence and grade of preoperative PVT, 286 LTs were divided into three groups： complete PVT （c-PVT）, partial PVT （p-PVT） and non-PVT, with 22, 30 and 234 LTs, respectively. Analyses were carried out to compare the incidence of early postoperative complications.RESULTS： PVT, inferior vena cava （IVC） thrombosis, hepatic artery thrombosis （HAT） and biliary complications were found postoperatively. All complications were detected by routine Doppler ultrasonography and diagnoses made by ultrasound were confirmed by clinical data or/and other imaging studies. Nine out of 286 LTs had postoperative PVT. The incidence of the c-Pv-r group was 22.7%, which was higher than that of the p-Pv-r group （3.3%, P 〈 0.05） and non- PVT group （1.3%, P 〈 0.005）. No difference was found between the p-PVT and non-PVT groups （P 〉 0.25）. Of the 9 cases with postoperative PVT, recanalizations were achieved in 7 cases after anticoagulation under the guidance of ultrasound, 1 case received portal vein thrombectomy and 1 case died of acute injection. Ten LTs had postoperative 1VC thrombosis. The c-PVT group had a higher incidence of IVC thrombosis than the non- PVT group （9.1% vs 2.6%, P 〈 0.05）; no significant difference was found between either the c-PV-T and p-PVT groups （9.1% vs 6.7%, P 〉 0.5） or between the p-PVT and non-PVT groups （P 〉 0.25）. Nine cases with IVC thrombosis were cured by anticoagulation under the guidance of ultrasound, and 1 case gained natural cure without any medical treatment after 2 mo. HAT was found in 2 non-PVT cases, giving a rate of 0.7% among 286 LTs. Biliary complications were seen in 12 LTs. The incidence of biliary complications in the c-PVT, p-PVT and non-PVT groups was 9.1%, 3.3% and 4.3%, respectively （P 〉 0.25 for all）, among which 2 stenosis led retransplantations and others were controlled by relative therapy.CONCLUSION： C-PVT patients tend to have a higher incidence of PVT and IVC thrombosis than non- PVT patients after LT. The incidence of postoperative complications in p-PVT patients does not differ from that of non-PVT patients, A relatively low incidence of HAT was seen in our study, Doppler ultrasonography is a convenient and efficient method for detecting posttransplant complications and plays an important role in guiding treatment.

Ultrasonic Extraction of Polysaccharides from Laminaria japonica and Their Antioxidative and Glycosidase Inhibitory Activities

In the present study, ultrasonic extraction technique （UET） is used to improve the yield of polysaccharides from Lami- naria japonica （LJPs）. And their antioxidative as well as glycosidase inhibitory activities are investigated. Box-Behnken design （BBD） combined with response surface methodology （RSM） is applied to optimize ultrasonic extraction for polysaccharides. The optimized conditions are obtained as extraction time at 54 min, ultrasonic power at 1050 W, extraction temperature at 80℃ and ratio of material to solvent at 1：50 （g mL-1）. Under these optimal ultrasonic extraction conditions, an actual experimental yield （5.75% ＋ 0.3%） is close to the predicted result （5.67%） with no significant difference （P〉0.05）. Vitro antioxidative and glycosidase inhibitory activities tests indicate that the crude polysaccharides （LJP） and two major ethanol precipitated fractions （LJP1 and LJP2） are in a concentration-dependent manner. LJP2 （30%-60% ethanol precipitated polysaccharides） possesses the strongest α-glucosidase in- hibitory activity and moderate scavenging activity against hydroxyl radicals （66.09% ±2.19%, 3.0 mg mL-l）. Also, the inhibitory activity against a-glucosidase （59.08% ± 3.79%, 5.0 mg mL-1） is close to that of acarbose （63.99% ± 3.27%, 5.0 mg mL-l）. LJP 1 （30% ethanol precipitated polysaccharides） exhibits the strongest scavenging activity against hydroxyl radicals （99.80%q-0.00%, 3.0mg mL-1） and moderate a-glucosidase inhibitory activity （47.76%± 1.92%, 5.0 mgmL-1）. LJP shows the most remarkable DPPH scav- enging activity （66.20%±0.11%, 5.0mgmL-1） but weakest a-glucosidase inhibitory activity （37.77%±1.30%, 5.0mgmL-1）. How- ever, all these LJPs exert weak inhibitory effects against a-amylase. These results show that UET is an effective method for extract- ing bioactive polysaccharides from seaweed materials. LJP 1 and LJP2 can be developed as a potential ingredient in hypoglycemic agents or functional food for the management of diabetes. This study provides scientific evidence and advances in the preparation technology and a hypoglycemic activities evaluation method for seaweed polysaccharides, especially glycosidase inhibition in com- bination with an antioxidative activity evaluation method.

Basket pattern blood flow signals discovered in a case of splenic hamartoma by power Doppler ultrasonography

We present the gray-scale ultrasonography （GSUS）, power Doppler ultrasonography （PDUS）, abdominal computed tomography （CT）, and magnetic resonance imaging （MRI） findings for a case of splenic hamartoma in a 27-year-old man, showing a φ 50 mm homogeneous, iso- and hypo-echoic splenic mass with evidence of a small plural cystic lesion. This splenic hamartoma showed increased vascularity on power Doppler sonograms. PDUS showed multiple circular blood flow signals inside the mass （i.e. a basket pattern）, which was consistent with the small plural cystic lesion shown by GSUS. Spectral analysis also confirmed arterial and venous flow. CT scans showed that the mass had lowdensity relative to the normal spleen and MRI showed that the mass was isodense, relative to the normal spleen. Therefore, CT and MRI are not useful for the diagnosis of splenic hamartoma. Ultrasonography can be used to diagnose splenic hamartoma without administration of a contrast matedal and therefore is an indispensable method for the diagnosis of splenic hamartoma.

Sonographic signs of neutropenic enterocolitis

AIM： To investigate the sonographic features at time of diagnosis and follow-up in patients with neutropenic enterocolitis. METHODS： The sonographic findings in 14 patients with neutropenic enterocolitis were described and evaluated regarding symptoms and clinical outcome. RESULTS： In all patients with neutropenic enterocolitis, the ileocoecal region was involved with wall thickening 〉10 mm. A transmural inflammatory pattern, hypervascularity of the thickened bowel wall and free abdominal fluid were the common findings. The sonographically revealed thickness of the bowel wall was associated with lethal outcome （P〈0.03）. In the 11 surviving patients, the improvement of clinical symptoms was accompanied by progressive reduction of intestinal wall thickness. CONCLUSION： High-end sonography of the bowel is a helpful tool for diagnosis, assessment of prognosis and follow-up of patients with neutropenic enterocolitis. The ultrasonographically revealed bowel thickness reflects the severity and the course of the disease, and seems to be predictive for the clinical outcome.

Ultrasonic-associated extraction of water soluble polysaccharides from defatted Korean pine kernel

Experiments of ultrasonic-associated extraction and hot water extraction of water soluble polysaccharides from defatted Korean pine （Pinus koraiensis） were conducted in Northeast Forestry University, Harbin, China. The factors affecting extraction yield and content, such as extracting temperature, extracting time, the ratio of water to defatted kernel and concentration of ethanol were analyzed under specific condition. The optimal extracting parameters for ultrasound-associated extraction were determined as the ultrasonic temperature 70℃, the ratio of defatted kernel to water 1：20, the extracting time 40 min, and ethanol concentration 80%. Under such extraction conditions, the yield of water soluble polysaccharide was 3.65% and the average content of polysaccharide was 45.38% in the raw polysaccharides which gained in the experiment. Both extraction yield and content of polysaccharides extracted with ultrasound-associated extraction were higher than that with hot water extraction. The study demonstrates that ultrasound is a reliable and extremely effective tool for the fast extraction of water soluble polysaccharide of Korean pine kernel.

FEASIBILITY STUDY OF AN ULTRASOUND CONTRAST AGENT(LEVOVIST) IN COLOR DOPPLER IMAGING OF LIVER NEOPLASMS

The purpose of this study was to determine the efficacy of using an ultrasound contrast agent(levovist)to enhance the color Doppler imaging of liver neoplasms.Thirty patients with hepatic tumors were enrolled in this study.After intravenous administration of levovist,the color Doppler signals of normal hepatic vessels were enhanced.In various hepatic tumors,the different patterns of tumor vascularity were observed,which had not been demonstrated in conventional non contrast color Doppler imaging.In 11 of 16 patients with hepatocarcinoma,additional color Doppler signals were observed in the central part of the tumors.On the contrary,3 patients with metastatic liver lesions the enhanced color Doppler signals appear only at the peripheral of tumors.A typical rim like color enhancement was seen in 2 of the 3 cases.In six patients with hepatic hemangiomas contrast enhanced color Doppler imaging demonstrated the blood vessels at the margin of the neoplasms.Contrast enhanced color Doppler imaging improves the visualization of the hepatic neoplasm vascularity.This technique holds great promise for detecting small liver tumors and differentiating hepatic neoplasms.

Role of echo Doppler ultrasonography in the evaluation of postprandial hyperemia in cirrhotic patients

AIM: To assess the role of echo-Doppler ultrasonography in postprandial hyperemia in cirrhotic patients by comparing the results with the hepatic vein catheterization technique.METHODS: Patients with cirrhosis, admitted to the portal hemodynamic laboratory were included into the study. After an overnight fast, echo-Doppler ultrasonography (basal and 30 min after a standard meal) and hemodynamic studies by hepatic vein catheterization (basal, 15 min and 30 min after a standard meal) were performed. Ensure Plus (Abbot Laboratories, North Chicago, IL) was used as the standard liquid meal. Correlation analysis of the echo-Doppler and hepatic vein catheterization measurements were done for the basal and postprandial periods.RESULTS: Eleven patients with cirrhosis (5 Child A, 4 Child B, 2 Child C) were enrolled into the study. After the standard meal, 8 of the 11 patients showed postprandial hyperemia with increase in portal blood flow, portal blood velocity and hepatic venous pressure gradient. Hepatic venous pressure gradient in the postprandial period correlated positively with postprandial portal blood velocity (r = 0.8, P < 0.05) and correlated inversely with postprandial superior mesenteric artery pulsatility index (r = -1, P < 0.01).CONCLUSION: Postprandial hyperemia can be efficiently measured by echo-Doppler ultrasonography and the results are comparable to those obtained with the hemodynamic studies.

The Influences of Ultrasonic on Embedding Nano Particles into Porous Fabric Materials

The feasibility of embedding 40nm ZnO particles into porous textile material by using ultrasonic and its influence factors were studied. Through investigations, it is proved that the higher the concentration of nanoparticle suspension is, the higher the weight of embedding percentage (EPW) is. However, the increasing trend of EPW will minish quickly when the concentration exceeds 1%. In addition, the longer the process time of ultrasonic is, the higher EPW is. EPW is always higher when the distance between film and ultrasonic transducer is 1/2λ and 3/2λ, and lower when the distance is 1λ and 2λ. For 40nm ZnO particles, EPW of the film effected by ultrasonic with the frequency of 42kHz reaches the maximum.

Comparison of mini-probe endoscopic ultrasonography with computed tomography scan in preoperative staging of esophageal cancer

Objective:To compare mini-probe endoscopic ultrasonography(MCUS)with computed tomography(CT)in pre-operative T and N staging of esophageal cancer,and to find out the MCUS parameters to judge lymph nodes metastasis for esophageal cancer.Methods:Thirty-five patients received both MCUS and CT preoperatively,on both of which the T and N stages were determined.The accuracy,sensitivity,specificity,positive predicting value and negative predicting value were compared with the postoperative pathological results.Results:The accuracy of MCUS was 85.7% in T staging and 85.7% and 80.0% in N staging by two different methods,which were 45.7% and 74.3%,respectively,by CT.Conclusion:MCUS is better than CT in preoperative staging for esophageal cancer.The ratio of short to long axis(S/L)combined with short axis is a useful way to determine lymph nodes metastasis.