捷联惯导系统内杆臂补偿方法及试验验证

在实际捷联惯组中,三只加速度计的比力测量对应于不同的点位置,如果直接作为捷联惯导算法的输入,角运动条件下会引起导航误差。对于加速度计非正交安装情形,在常规静态标定模型基础上,推导了考虑内杆臂效应后的动态标定模型。以导航速度为观测量,建立了加计组合内杆臂补偿的一般模型方程。针对激光捷联惯性组合,设计了简便的试验方法用于辨识内杆臂参数,高强度的摇摆试验表明内杆臂补偿有效地提高了导航精度,速度误差降低达77%以上。

舰用高精度激光陀螺惯导内杆臂误差分析及补偿方法研究

对于高精度激光陀螺旋转惯导系统,大部分惯性器件误差都能够通过惯性测量单元(IMU)旋转而调制掉,内杆臂误差不仅不能够被调制掉,反而因为IMU旋转将误差引入到系统对准和导航过程中。基于此,本文对内杆臂误差进行分析与建模,推导内杆臂误差与导航速度误差之间的数学表达式,通过分析确定内杆臂长度和振动频率是影响内杆臂误差的2个因素,并提出基于内杆臂长度的误差补偿方法。最后,通过试验对内杆臂误差模型和补偿方法进行了验证。

捷联惯导加速度计内杆臂误差分析与补偿

针对捷联惯导系统内杆臂误差的估计和补偿问题,提出了一种角度随正弦规律变化的旋转方案。通过推导内杆臂误差与载体角速度和角加速度之间的关系,分析内杆臂误差对捷联惯导系统的影响,基于内杆臂误差模型设计正弦旋转的标定路径,采用分段线性定常系统(PWCS)和奇异值分解(SVD)的方法对系统进行可观测性分析,设计卡尔曼滤波器对内杆臂误差进行估计。仿真结果表明:本文设计的正弦旋转方案使得9个内杆臂误差完全可观;在相同的摇摆频率下,摇摆幅值越大,内杆臂误差的估计精度越高;与两轴联动式误差激励方式相比,滤波估计时间减少50%以上。

惯性测量单元内杆臂标定卡尔曼滤波方法

在高动态环境下,由内杆臂引起的尺寸效应误差是高精度捷联惯导系统的重要误差源之一。从原理上分析了内杆臂误差的产生机理,推导了内杆臂误差的动态误差模型,并结合系统误差模型推导了内杆臂的标定模型,选取考虑了外杆臂误差的速度误差为系统观测量,提出了基于卡尔曼滤波的内杆臂参数辨识方法。试验结果表明,内杆臂标定重复性精度优于2 mm,快速旋转试验中,内杆臂误差补偿后,速度误差减小90%,摇摆试验中的导航精度也得到显著提升。

捷联惯导寻北系统中内杆臂误差的分析与补偿

为解决高精度激光陀螺捷联惯导寻北系统中,旋转调制对内杆臂效应误差起不到消除效果,反而会将误差引入寻北导航解算中的问题,提出具体的补偿方法。建模分析寻北过程中的内杆臂误差,推导具体的内杆臂误差效应的数学表达式,分析确定影响内杆臂误差的2个因素,并通过实验进行仿真验证。结果表明:内杆臂误差不会引起定位误差的发散;内杆臂效应导航速度增量与旋转中心无关,而与内杆臂长度、惯性测量单元(inertial measuring unit,IMU)的旋转角速度成正比。

拆分杆组的一种通用有效方法

从机构组成原理出发,通过引入“虚拟原动件”的概念,提出了一种简单通用、行之有效的拆分杆组的新方法。

3D股骨力线测量在人工全膝关节置换术中的应用

目的探讨人工全膝关节置换(total knee arthroplasty,TKA)术中在3D模型及2D图像上测量股骨外翻角及股骨髓内杆进针点位置的应用。方法收集105例患者下肢全长CT血管造影(CT angiography,CTA)影像学资料,其中男65例,女40例;年龄26~69岁,平均(52.40±3.22)岁;左膝49例,右膝56例。将105例患者CT数据导入Mimics 19.0软件并对股骨进行3D重建,3D股骨模型用Fluoroscopy Simulation透视工具获取2D股骨图像。比较3D模型及2D图像上测量的股骨外翻角及股骨髓内杆进针点,采用Shapiro-Wilk检验对所得数据进行分析。结果(1)股骨外翻角在3D模型与2D图像测量参数差异无统计学意义(P>0.05)。而3D模型与2D图像在股骨髓内杆进针点与whiteside’s线及股骨髓内杆进针点与髁间凹最顶点的距离方面比较,差异有统计学意义(P<0.05)。(2)3D模型测量参数中股骨外翻角、股骨髓内杆进针点与髁间凹顶点的距离,在不同性别中其差异有统计学意义(P<0.05);而股骨髓内杆进针点与whiteside’s线的距离差异无统计学意义(P>0.05)。(3)年龄与股骨外翻角的相关性分析,两者呈正相关r=0.54(P<0.001)。结论在2D图像中基于whiteside’s线及股骨髁间凹最顶点来获得的股骨髓内杆进针点不是可靠的参考依据,因此在X线片上测量的股骨髓内杆进针点的数据不能为TKA提供精准的参数。而股骨外翻角在2D图像上测量的结果具有重要参考意义,且随年龄及性别的不同发生改变。

弹载惯组的杆臂效应补偿

在舰载系统和机载系统,当子母惯导之间存在杆臂长度时,在传递对准中通常先消除杆臂效应误差再进行对准,以提高对准精度。在弹载环境中人们往往忽视杆臂效应,受制于弹体空间的限制,弹载惯组中的加速度计通常根据系统体积最小的原则寻找剩余空间布置,此时三个加速度计测量的是弹体三个不同点的加速度,不但存在外杆臂还存在内杆臂,导致惯组总体的杆臂误差。通过深入分析内外杆臂的形成机理,提出对弹载惯组也应进行杆臂效应误差补偿,对补偿算法进行了仿真和实验研究。系统半物理仿真表明补偿后在某些弹道条件下可以显著提高弹体攻击精度,其攻击目标误差由120m缩小为26 m。

套管加固法加固轴压钢管柱力学性能研究

套管加固法加固轴压钢管柱是一种能有效抑制轴压钢管柱屈曲失稳的加固方法,具有理论清晰、构造简单、安全可靠、技术合理、经济适用等显著优点。本文基于ABAQUS软件模拟分析内杆长细比及套管内杆长度比对杆件在轴向压力作用下的破坏机理及极限承载力的影响,选取4种不同套管内杆长度比和6组内杆长细比不同的杆件进行有限元模拟分析,得出套管内杆长度比及内杆长细比对杆件轴压极限承载力的影响规律,为套管加固法在工程中的应用提供一定的设计依据。

36维Kalman滤波的激光陀螺捷联惯导系统级标定方法

分析了系统级标定的研究现状,建立了惯导系统误差模型。额外考虑加速度计二次项误差系数与内杆臂参数对系统的影响,提出了一种36维Kalman滤波系统级标定方法。设计了合适的标定路径,建立了Kalman滤波模型。仿真及实验结果表明,激光陀螺和加速度计零偏估计精度分别优于0.001(°)/h和9μg,标度因数误差估计精度分别优于3 ppm(1 ppm=10-6)和2 ppm,安装误差角估计精度分别优于1″和3″,二次项误差系数估计精度优于4×10-10 s2/m,内杆臂参数估计精度优于3 mm,满足高精度惯导系统的标定要求。

捷联惯导加速度计尺寸效应误差建模及其标定

高动态条件下,加速度计(简称加计)的尺寸效应将成为捷联惯导系统精确导航的重要误差源。这个误差源于加计组合中三个加计振动中心(有效的加速度测量点)的不重合。从几何角度对加计尺寸效应误差进行了建模。设计了三类基于精密三轴速率转台的加计尺寸标定方案,即匀角速度旋转、匀角加速度旋转和正弦角加速度旋转方案。以旋转过程中捷联惯导系统的速度输出作为量测,利用Kalman滤波器可以实现对加计尺寸系数的有效估计。利用分段定常系统可观性分析方法研究表明,三类旋转标定机动均能使系统状态完全可观测。仿真结果证明了三类标定方案的有效性,而以匀角速度旋转方案估计过程最平稳,以正弦角加速度旋转方案估计精度最高。

基于高阶卡尔曼滤波的激光捷联惯导系统级标定方法

随着激光捷联惯导系统的不断发展,系统对于误差标定的精度要求也在不断提高。在现有系统级标定算法的基础上,全面考虑了惯性器件零偏、安装误差角、标度因数误差、加速度计二次项、内杆臂等误差,并在计算速度和位置误差观测量时考虑了外杆臂误差,提高了激光捷联惯导系统误差模型的准确性,并基于此设计了一种基于高阶卡尔曼滤波算法的系统级标定方法。通过实验验证表明,与分立式标定方法相比,所提出的系统级标定方法具有更高的标定精度,能够满足高精度激光捷联惯导系统的标定需求。

光纤陀螺捷联惯导系统艇上系泊状态自标定方法

从实际工程使用角度出发,提出了一种在系泊状态下的系统级自标定方案,避免了惯导系统在艇上的反复拆装。提出的系统级标定方法设计了15位置转位方案,可以通过Kalman滤波对陀螺仪和加速度计的零次项误差,标度因数误差,安装误差进行精确估计,除了对以上误差参数的估计外,对影响导航精度的内杆臂参数和加速度计正负通道非对称误差也可以进行估计。并根据系泊状态的特殊晃动环境,设计了零相位延迟的低通滤波器从惯导系统的速度解算中得到速度误差,保证了惯导系统在不依赖外界输入条件下完成自标定任务。仿真及实验结果表明,该方法能在系泊状态下准确估计出全部误差变量,且与静基座标定结果相符,具有实际应用价值。

Cloning of Endo-β-Glucanase Ⅲ and Expression in Eerevisiae Fermentum

Objective The aim was to construct bioengineering strains that could degrade the cellulosic solid waste. Method The cDNA of endo-β-glucanase III of Trichoderma vi ride AS313711 was cloned by RT-PCR method. After sequenced, this gene was constructed to expression vector pESP-2, and then the plasmid was transformed into competent cell of cerevisiae fermentum by electric shock, the transformant was then obtained. The enzyme activity of this transformant at the different temperatures and pH was measured by DNS method. Result The length of ORF of EG III was 1 257 bp, encoding 418 amino acids, while the deduced molecular weight was 44.1 × 103 kD. Conclusion The enzyme activity of EG III was the highest when it was at PH 4.9 and tempeture was of 60℃. Then the corresponding enzyme activity was about 100%.

Effect of Lactobacillus rhamnosus HN001 and Bifidobacterium longum BB536 on the healthy gut microbiota composition at phyla and species level: A preliminary study

AIMTo evaluate the ability of Lactobacillus rhamnosus HN001 and Bifidobacterium longum BB536 to colonize the intestinal environment of healthy subjects and modify the gut microbiota composition.METHODSTwenty healthy Italian volunteers, eight males and twelve females, participated in the study. Ten subjects took a sachet containing 4 × 109 colony-forming units (CFU) of Bifidobacterium longum BB536 and 109 CFU of Lactobacillus rhamnosus HN001, 30 min before breakfast (pre-prandial administration), while ten subjects took a sachet of probiotic product 30 min after breakfast (post-prandial administration). The ability of Lactobacillus rhamnosus HN001 and Bifidobacterium longum BB536 to colonize human gut microbiota was assessed by means of quantitative real-time PCR, while changes in gut microbiota composition were detected by using Ion Torrent Personal Genome Machine.RESULTSImmediately after 1-mo of probiotic administration, B. longum BB536 and L. rhamnosus HN001 load was increased in the majority of subjects in both pre-prandial and post-prandial groups. This increase was found also 1 mo after the end of probiotic oral intake in both groups, if compared to samples collected before probiotic consumption. At phyla level a significant decrease in Firmicutes abundance was detected immediately after 1-mo of B. longum BB536 and L. rhamnosus HN001 oral intake. This reduction persisted up to 1 mo after the end of probiotic oral intake together with a significant decrease of Proteobacteria abundance if compared to samples collected before probiotic administration. Whereas, at species level, a higher abundance of Blautia producta, Blautia wexlerae and Haemophilus ducrey was observed, together with a reduction of Holdemania filiformis, Escherichia vulneris, Gemmiger formicilis and Streptococcus sinensis abundance. In addition, during follow-up period we observed a further reduction in Escherichia vulneris and Gemmiger formicilis, together with a decrease in Roseburia faecis and Ruminococcus gnavus abundance. Conversely, the abundance of Akkermansia muciniphila was increased if compared to samples collected at the beginning of the experimental time courseCONCLUSIONB. longum BB536 and L. rhamnosus HN001 showed the ability to modulate the gut microbiota composition, leading to a significant reduction of potentially harmful bacteria and an increase of beneficial ones. Further studies are needed to better understand the specific mechanisms involved in gut microbiota modulation.

Mechanical properties and reinforcement effect of jointed rock mass with pre-stressed bolt

Pre-stressed bolt anchorage is the key technology for jointed rock masses in rock tunnelling,slope treatment and mining engineering.To investigate the mechanical properties and reinforcement effect of jointed rock masses with pre-stressed bolts,in this study,uniaxial compression tests were conducted on specimens with different anchoring types and flaw inclination angles.ABAQUS software was used to verify and supplement the laboratory tests.The laws of the uniaxial compressive strength(UCS)obtained from the numerical simulations and laboratory tests were consistent.The results showed that under the same flaw angle,both the UCS and elastic modulus of the bolted specimens were improved compared with those of the specimens without bolts and the improvements increased with an increase in the bolt pre-stress.Under the same anchoring type,the UCS and elastic modulus of the jointed specimens increased with an increase in the flaw angle.The pre-stressed bolt could not only restrain the slip of the specimens along the flaw surface but also change the propagation mode of the secondary cracks and limit the initiation of cracks.In addition,the plot contours of the maximum principal strain and the Tresca stress of the numerical models were influenced by the anchoring type,flaw angle,anchoring angle and bolt position.

Primary gastric lymphoma

AIM:The purpose of this review is to describe the various aspects of primary gastric lymphoma and the treatment options currently available. METHODS:After a systematic search of Pubmed,Medscape and MDconsult,we reviewed and retrieved literature regarding gastric lymphoma. RESULTS:Primary gastric lymphoma is rare however,the incidence of this malignancy is increasing.Chronic gastritis secondary to Helicobacter pylori (H pylori) infection has been considered a major predisposing factor for MALT lymphoma. Immune histochemical marker studies and molecular biology utilizing polymerase chain reaction have facilitated appropriate diagnosis and abolished the need for diagnostic surgical resection.Advances in imaging techniques including Magnetic Resonance Imaging (MRI) and Endoscopic Ultrasonography (EUS) have helped evaluation of tumor extension and invasion. The clinical course and prognosis of this disease is dependent on histopathological sub-type and stage at the time of diagnosis.Controversy remains regarding the best treatment for early stages of this disease.Chemotherapy,surgery and combination have been studied and shared almost comparable results with survival rate of 70-90%.However,chemotherapy possesses the advantage of preserving gastric anatomy. Radiotherapy alone has been tried and showed good results. Stage IIIE,IVE disease treatment is solely by chemotherapy and surgical resection has been a remote consideration. CONCLUSION:We conclude that methods of diagnosis and staging of the primary gastric lymphoma have dramatically improved.The modalities of treatment are many and probably chemotherapy is superior because of high success rate, preservation of stomach and tolerable complications.

Prevalence of Helicobacter pylori infection and intestinal metaplasia in subjects who had undergone surgery for gastric adenocarcinoma in Northwest Italy

AIM： To investigate the seroprevalence of Helicobacter pylori （Hpylori） infection and its more virulent strains as well as the correlation with the histologic features among patients who had undergone surgery for gastric cancer （GC）. METHODS： Samples from 317 （184 males, 133 females, mean age 69±3.4 years） consecutive patientswho had undergone surgery for gastric non-cardia adenocarcinoma were included in the study. Five hundred and fifty-five （294 males, 261 females, mean age 57.3±4.1 years） patients consecutively admitted to the Emergency Care Unit served as control. Histological examination of tumor, lymph nodes and other tissues obtained at the time of surgery represented the diagnostic ＂gold standard＇： An enzyme immunosorbent assay was used to detect serum anti-H pylori （IgG） antibodies and Western blotting technique was utilized to search for anti-CagA protein （IgG）. RESULTS： Two hundred and sixty-one of three hundred and seventeen （82.3%） GC patients and 314/555 （56.5%） controls were seropositive for anti-H pylori （P〈0.0001; OR, 3.58; 95%CI, 2.53-5.07）. Out of the 317 cases, 267 （84.2%） were seropositive for anti-CagA antibody vs 100 out of 555 （18%） controls （P〈0.0001; OR, 24.30; 95%CI, 16.5-35.9）. There was no difference between the frequency of H pylori in intestinal type carcinoma （76.2%） and diffuse type cancer （78.8%）. Intestinal metaplasia （IM） was more frequent but not significant in the intestinal type cancer （83.4% vs 75.2% in diffuse type and 72.5% in mixed type）. Among the patients examined for IM, 39.8% had IM type Ⅰ, 8.3% type Ⅱ and 51.9% type Ⅲ （type IU vs others, P = 0.4）. CONCLUSION： This study confirms a high seroprevalence of H pylori infection in patients suffering from gastric adenocarcinoma and provides further evidence that searching for CagA status over H pylori infection might confer additional benefit in identifying populations at greater risk for this tumor.

H pylori infection in patients with Behcet's disease

AIM:To evaluate endoscopic findings and the prevalence of H pylori in patients with Behcet's disease (BD) who have upper gastrointestinal symptoms. METHODS:The patients with BD diagnosed according to the International Study Group and followed up in the Department of Dermatology and other related departments and who had any upper gastrointestinal complaints,were included in this study. Forty-five patients with BD and 40 patients in the control group were evaluated by upper gastrointestinal endoscopy and two biopsied specimens were taken during endoscopy for H pylori . A two-week triple therapy for H pylori eradication was administered to H pylori positive patients. Two months after the treatment,the patients were evaluated by urea-breath test for eradication control. RESULTS:Patients with BD had a mean age of 36.2 ± 11.4 years (18-67 years). The mean follow-up time was 35 ± 14 mo (16-84 mo). Aphthous or deep ulcer in esophagus,stomach and duodenum had never been confirmed by endoscopic examination. Most gastric lesions were gastric erosion (40%) and the most duodenal lesions were duodenitis (17.5%) in two groups. H pylori was positive in 33 patients (73.3%) with BD. The two-week triple eradication therapy was successful in 75% of the patients. There was no difference between the groups in respect to prevalence of H pylori (73.3% vs 75%,P > 0.05),and eradication rate (75% vs 70%,P > 0.05). CONCLUSION:Endoscopic findings,eradication rate and prevalence of H pylori were similar in patients withBD and control group.

Helicobacter pylori infection and endocrine disorders:Is there a link?

Helicobacter pylori(H pylori) infection is a leading world-wide infectious disease as it affects more than half of the world population and causes chronic gastritis,peptic ulcer disease and gastric malignancies.The infection elicits a chronic cellular inflammatory response in the gastric mucosa.However,the effects of this local inflammation may not be confi ned solely to the digestive tract but may spread to involve extraintestinal tissues and/or organs.Indeed,H pylori infection has been epidemiologically linked to extra-digestive conditions and diseases.In this context,it has been speculated that H pylori infection may be responsible for various endocrine disorders,such as autoimmune thyroid diseases,diabetes mellitus,dyslipidemia,obesity,osteoporosis and primary hyperparathyroidism.This is a review of the relationship between H pylori infection and these endocrine disorders.