Ballistic limit velocity of small caliber projectiles against SS400 steel plates:Live fire experiments and empirical models

This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.

Diagnostic utility of small-caliber and conventional endoscopes for gastric cancer and analysis of endoscopic false-negative gastric cancers

AIM: To analyze the diagnostic utility of a small-caliber endoscope(SC-E) and clinicopathological features of false-negative gastric cancers(FN-GCs). METHODS: A total of 21638 esophagogastroduodenoscopy(EGD) gastric cancer(GC) screening examinations were analyzed. Secondary endoscopic examinations(n = 3352) were excluded because most secondary examinations tended to be included in the conventional endoscopy(C-E) group. Detection rates of GCs and FN-GCs were compared between SC-E and C-E groups. FN-GC was defined as GC performed with EGD within the past 3 years without GC detection. Macroscopic types, histopathological characteristics and locations of FN-GCs were compared with firstly foundgastric cancers(FF-GCs) in detail. RESULTS: SC-E cases(n = 6657) and C-E cases(n = 11644), a total of 18301 cases, were analyzed. GCs were detected in 16(0.24%) SC-E cases and 40 C-E(0.34%) cases(P = 0.23) and there were 4 FN-GCs(0.06%) in SC-E and 13(0.11%) in C-E(P = 0.27), with no significant difference. FN-GCs/GCs ratio between SC-E and C-E groups was not significantly different(P = 0.75). The comparison of endoscopic macroscopic types of FN-GCs tended to be a less advanced type(P = 0.02). Histopathologically, 70.6% of FN-GCs were differentiated and 29.4% undifferentiated type. On the other hand, 43.0% of FF-GCs were differentiated and 53.8% undifferentiated type, so FN-GCs tended to be more differentiated type(P = 0.048). CONCLUSION: The diagnostic utility of SC-E for the detection of GCs and FN-GCs was not inferior to that of C-E. Careful observation for superficially depressed type lesions in the upper lesser curvature region is needed to decrease FN-GCs.

IN VIVO EFFECT OF HEPARIN PRETREATMENT OF SMALL-CALIBER DECELLULARIZED XENOGRAFT

Objective To develop a new vascular xenograft and to compare the in vivo behavior of thrombogenicity and intimal hyperplasia in the heparin-treated and the non-heparin-treated decellularized xenografts.Methods Canine common carotid arteries were decellularized by enzymatic and detergent extraction procedures.Then a part of decellularized vascular grafts were covalently linked with heparin.Xenografts with(n=24)and without(n=24)heparin treatment were implanted in rabbits' left and right carotid artery respectively as bypass grafts.Graft patency were checked by Duplex ultrasonography at 3 and 6 months after implantation.Twelve rabbits were euthanized randomly at 3 and 6 months respectively and bilateral grafts were explanted.Histological examination and immunohistochemical staining were performed to observe the vascular remodeling.The efficiency of heparin release was demonstrated with toluidine blue staining.HE staining and micrograph analysis system were used for valuating the intima hyperplasia(IH)of bilateral grafts.Results During implantation,thrombosis rate was 4% in the heparin-treated xenografts and 25% in the non-heparin-treated xenografts after 3 weeks(P<0.05).After 6 months,it was 8% versus 58% respectively(P<0.01).Both xenografts of two groups harvested at the end of 3 or 6 months showed a satisfactory cellular reconstruction of either smooth muscle cells or endothelial cells.Intimal hyperplasia in the heparin-treated vascular was less than in the non-heparin treated xenografts.In addition,intimal hyperplasia was liable to appear close to the proximal and distal anastomotic stoma.Toluidine blue staining demonstrated that heparin was slowly released during 6 months.Conclusion This study provides a new strategy to develop a small-caliber vascular xenograft through enzymatic-detergent extraction and heparin treatment.Heparin treatment of the decellularized xenograft is helpful for improving bypass graft patency and reducing intimal hyperplasia.If there was no thrombus,bilateral bypass grafts will undergo a vessel remodeling procedure.Canine common carotid artery treated by detergent and enzymatic extraction and heparin treatment may be used as a new small-caliber vascular xenograft.

Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses

Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the wall.In our previous studies,it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end anastomoses.In order to better understand the beneficial effect of the swirling flow,we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow conditions.The numerical models were created based on our previous experimental studies.The simulation results revealed that when compared with the normal flow,the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion tube.The present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts,or in end-to-end anastomoses as observed in our previous experimental study,was possibly through a mechanism of platelet transport,in which the swirling flow reduced the near-wall concentration of platelets.

Shenqi Fuzheng injection combined with GP chemotherapy in the treatment of advanced non-small cell lung cancer： a meta-analysis

Objective： To evaluate the clinical efficacy of Shenqi Fuzheng injection combined with gemcitabine plus cisplatin（GP） in the treatment of advanced non-small cell lung cancer （NSCLC）. Methods： we performed a systematicsearch in the electronic databases such as Cochrane Library, Pubmed, Embase, Chinese Journal Full-text Database,Chinese Biomedical Literature Database, Chinese Science and Technology Periodical Full-text Database andWanfang Database up to 30 January 2017. Randomized controlled trials （RCT） of Shenqi Fuzheng Injectioncombined with GP chemotherapy in the treatment of advanced NSCLC were searched, and all the RCTs wereconducted on methodological quality assessment. Data extraction and data analysis were according to standards ofCochrane systematic review. Results： Eight trials were included including a total of 701 patients. Meta-analysisresults： Shenqi Fuzheng injection combined with GP chemotherapy could significantly improve the functionalstatus of patients with NSCLC （OR = 3.44, 95% CI [2.26, 5.25], P 〈 0.0001） and clinical treatment efficacy （OR =（OR = 0.31, 95%CI [0.20, 0.47], P 〈 0.0001. The rate of leukopenia （OR = .31, 95%CI [0.20,0.47], P 〈 0.0001）,thrombocytopenia （OR = 0.58, 95%CI [0.37, 0.91], P = 0.020）, hemoglobin decline （（OR = 0.31, 95%CI [0.16,0.59], P = 0.0004） and incidence of gastrointestinal reactions （OR = 0.58,P 〈 0.05） could be reduced. Conclusion：Shenqi Fuzheng injection combined with GP chemotherapy in the treatment of advanced NSCLC obtainedsignificantly clinical efficacy. The quality of the literature incorporated is low, the conclusion requires high-qualityresearch to further prove.

Molecular Engineering Design for High-Performance Aqueous Zinc-Organic Battery

Novel small sulfur heterocyclic quinones(6a,16adihydrobenzo[b]naphtho[2′,3′:5,6][1,4]dithiino[2,3-i]thianthrene-5,7,9,14,16,18-hexaone(4S6Q)and benzo[b]naphtho[2′,3′:5,6][1,4]dithiino[2,3-i]thianthrene-5,9,14,18-tetraone(4S4Q))are developed by molecule structural design method and as cathode for aqueous zincorganic batteries.The conjugated thioether(–S–)bonds as connected units not only improve the conductivity of compounds but also inhibit their dissolution by both extendedπ-conjugated plane and constructed flexible molecular skeleton.Hence,the Zn//4S6Q and Zn//4S4Q batteries exhibit satisfactory electrochemical performance based on 3.5 mol L-1(M)Zn(ClO4)2electrolyte.For instance,the Zn//4S6Q battery obtains 240 and 208.6 mAh g^(-1)of discharge capacity at 150 mA g^(-1)and 30 A g^(-1),respectively.The excellent rate capability is ascribed to the fast reaction kinetics.This system displays a superlong life of 20,000 cycles with no capacity fading at 3 A g^(-1).Additionally,the H+-storage mechanism of the 4S6Q compound is demonstrated by ex situ analyses and density functional theory calculations.Impressively,the battery can normally work at-60℃benefiting from the anti-freezing electrolyte and maintain a high discharge capacity of 201.7 mAh g^(-1),which is 86.2%of discharge capacity at 25℃.The cutting-edge electrochemical performances of these novel compounds make them alternative electrode materials for Zn-organic batteries.

CYFRA 21-1 as an early predictor of first line chemotherapy response in advanced non small cell lung cancer

Objective： In an era of ever evolving, promising new therapies for advanced non small cell lung cancer （NSCLC）, early predictors of response to therapy, are needed. We evaluated early variations in CYFRA 21-1 serum levels of patients with advanced NSCLC receiving first line chemotherapy and correlated the results with objective tumor response. Methods： 29 consecutive, previously untreated, patients of advanced non small cell lung cancer, with measurable disease on CT scan were evaluated. All patients were treated with conventional systemic chemotherapy, although the choice of chemotherapy was left to the discretion of the treating physicians. Serum samples were obtained immediately before the start of 1st and 2nd cycles of chemotherapy. CYFRA 21-1 was measured with an electrochemiluminescense immunoassay on an automatic analyzer （Elecsys 2000; Roche Diagnostics）. Response was evaluated using Response evaluation criteria in solid tumors （RECIST） criteria. Results： 10 patients had partial response, 9 patients had stable disease and 9 had progressive disease. None of the patients had complete response. 21/29 （72%） patients had an elevated baseline value of CYFRA 21-1.62% patients （18/29） had a decrease in CYFRA 21-1 after 1 cycle of chemotherapy. The average reduction in the 2nd reading was irrespective of whether baseline value was normal or not. The average reduction was statistically significant （P = 0.002; 95% CI, from 0.8369 to 3.49464; t test）. 8 out of 10 （80%） patients with partial response had a reduction in their 2nd reading of. CYFRA （P = 0.019; 95% CI, from 0.81965 to 7.20035; t test） which was significant. We also observed that 6/9 （66%） patients whose disease remains stable also had a decrease in their subsequent reading （P = 0.0106; 95% CI, from -0.44942 to 3.82720; t test）, though it was not significant statistically. Although 5 out of 9 （55%） patients, who had an increase in their CYFRA 21-1 level, had progressive disease, but it was not statistically significant （P = 0.537; 95% CI, from -1.20021 to 2.13354; ttest）. 14 out of 19 （73%） who either had partial response or had stable disease, had a reduction in their 2nd value of CYFRA 21-1 and was significant statistically （P = 0.004; 95% CI, from 0.74792 to 3.50208; t test）. We also observed that except for 1 patient, all patients who had a decrease of 42% or more in their subsequent CYFRA 21-1 level, were those who had either responded to chemotherapy or had stable disease （P = 0.001）, which was statistically significant. Conclusion： We can conclude that monitoring of serum marker CYFRA 21-1, early dudng first-line chemotherapy may be a useful prognostic tool for evaluation of early tumor response in patients with advanced NSCLC.

The New Molecular Entity Evolocumab, One Kind of PCSK9 Inhibitor, Reduce Plasma Small Size LDL-Cholesterol Levels by Using a New Standardized Method of Measuring LDL Size

Aims: There has been no evidence on the effects of evolocumab, protein convertase subtilisin/kexin type 9 (PCSK9) inhibitor, on small size LDL. We observationally investigated the efficacy and side effects of evolocumab on the LDL subfraction particle diameter using PAGE system for lipoprotein analysis. Methods: We defined 30 patients with high-risk hyperlipidemia. As for analysis of LDL subfraction profile, we used polyacrylamide gel electrophoresis three methods: 1) 3% nondenatured poly-acrylamide gel electrophoresis method (3%PAGE), 2) 2% - 16% nondenatured poly-acrylamide gradient gel electro-phoresis method (2% - 16% GGE) and 3) 2.7% - 5% GGE. Evolocumab 140 mg/day administered together with statin significantly improved serum total cholesterol (TC), triglyceride (TG), high-dense lipoprotein-cholesterol (HDL-C), and LDL-C after four-week treatment. Results: TC, TG, HDL-C and LDL-C levels were improved by, respectively, 33%, 20%, 10%, and 54%. The mean LDL size significantly increased from 25.6 ± 0.4 nm to 26.4 ± 0.8 nm. The small dense LDL-cholesterol (sdLDL-C), large buoyant LDL-cholesterol (lbLDL-C), and mid-band lipoprotein-cholesterol were reduced, respectively. Therefore, the preliminary study on this paper can be the first step into a new insight on the world of lipid metabolism. Conclusion: Short-term administration of evolocumab addedons to statin therapy, significantly reduced small size LDL levels.

Development Strategies of E-commerce for Small and Medium - sized Enterprises

In the economic structure of our country, small and medium-sized enterprises （SMEs） are the most important part of the backbone, with the continuous popularization of the Internet, e-commerce has gradually become a business model that the current small and medium enterprises must face and accept, The development of enterprises is of great signifi cance. In this context, the article first introduced the importance of the development of e-commerce SMEs, and then based on the actual operation of the community put forward and analyzed the current e-commerce development under the existing problems, and finally based on the actual lack of effective Development Strategy of E - commerce for Small and Medium - sized Enterprises.

Mechanism of lncRNA SNHG19 miR-299-5p MAPK6 signaling axis promoting metastasis of non-small cell lung cancer cells

Objective The aim of this study was to explore the mechanism behind lncRNA small nucleolar RNA host gene 19(lncRNA SNHG19)/microrNA-299-5P(miR-299-5p)/mitogen-activated protein kinase 6(MAPK6)signaling axis promoting metastasis of non-small cell lung cancer(NSCLC).Methods To analyze the abnormal expression of lncRNAs in NSCLC,50 surgically resected NSCLC and adjacent tissue samples were collected from August 2021 to August 2022.The mRNA expression levels of lncRNA SNHG19,Mir-299-5p,and MAPK6 were detected by qRT-PCR.The functions of lncRNA SNHG19,Mir-299-5p and MAPK6 were investigated by CCK-8,clone formation,EdU,scratch,Transwell western blotting(WB)and in vivo xenograft assay.RNA fluorescence in-situ hybridization(FISH),RNA pull-down,dual luciferase reporter,and RNA co-immunoprecipitation assays were used to explore the mechanism of action between lncRNA SNHG19,miR-299-5p,and MAPK6.Results High expression of lncRNA SNHG19 was correlated with poor prognosis,tumor size,lymph node metastasis,and TNM stage in NSCLC patients(P<0.05).Cell function experiments showed that lncRNA SNHG19 could improve the proliferation,clone formation,migration,and invasion ability of A549 cells both in vitro and in vivo(all P<0.05)and increased the relative expression levels of vimentin and MAPK6(P<0.05).The relative expression level of E-cadherin was decreased(P<0.05).lncRNA SNHG19 can interact with Mir-299-5p and regulate the expression level of MAPK6.Conclusion lncRNA SNHG19 is upregulated in NSCLC tissues and cells,and its high expression is associated with tumor progression and poor survival.Moreover,it can act as a molecular sponge for Mir-299-5p to regulate MAPK6 expression and promote the proliferation and metastasis of A549 cells.

基于身管应变的小口径火炮弹丸速度测试方法

针对传统火炮弹丸速度测试方法中存在难以获取整条速度曲线、易受环境影响、体积庞大、成本较高、操作复杂等问题,提出了一种基于身管应变的小口径火炮弹丸速度测试方法。基于30 mm口径火炮设计了应变测试仪,实现身管外壁应变测试。根据厚壁圆筒理论计算得出火炮膛压曲线,通过弹底压力解算模型得出弹底压力曲线,与弹载存储测试方法得到的弹底压力曲线进行对比。结合弹丸运动方程得出弹丸速度曲线,采用四阶龙格库塔算法建立弹丸速度仿真模型,将应变测试、弹载存储测试得到的弹丸速度曲线与仿真曲线进行对比。结果表明:应变测试、弹载存储测试与仿真弹丸速度曲线趋势基本吻合,最大速度误差分别为1.1%和0.5%,验证了应变测试方法的可行性,为小口径火炮弹丸测速开辟了新途径。

小口径弹载遥测系统天线设计

天线是弹载遥测系统的核心器件。针对小口径弹载遥测系统的特殊需求,开展弹载天线设计。采用圆极化模式消除炮弹飞行过程中自旋对遥测信号的影响;通过扩展天线的波束宽度适应炮弹的曲线弹道;为满足小口径炮弹对天线小尺寸的需求,通过采用高介电常数介质基板并对辐射单元开槽实现天线小型化;天线和弹载遥测系统板卡之间采用插针相连以实现天线的抗过载要求。对所设计的天线进行试制加工,并测得其阻抗带宽为24 MHz,沿轴线±80°内的轴比均小于3 dB,且其顶点处增益为2.18 dBi。测试结果表明此天线的性能够满足实际使用需求。

小口径定距空爆弹末端防空拦截实时模拟及开舱距离研究

针对现有小口径定距空爆弹末端防空拦截及开舱距离模拟中,无法体现开舱后子弹云团与目标的动态交会过程,并忽略了定距空爆引信实际启动规律,导致毁伤效能评估不准确的问题,开展小口径定距空爆弹末端防空拦截实时模拟及开舱距离进行研究。通过建立多束定向预制破片战斗部、弹目交会及以巡航导弹为拦截目标的等效目标数值模型,搭建小口径定距空爆弹末端防空拦截实时模拟平台。基于实时模拟平台,引入武器系统误差与定距空爆引信实测启动规律,分析炮弹在不同射击距离下开舱距离与毁伤效能的关系,并对小口径定距空爆弹引信技术发展方向进行展望。研究结果表明,引信实际启动规律使得最优毁伤效能随射击距离的增加而减少的幅度增大,在射击远距离目标时,0~20 m的开舱距离内都存在着较高的完全脱靶率。

小口径人工血管的研究现状及展望

近年来,由于心血管疾病发生率逐渐上升,临床上对再生血管的需求日益增加。目前,大口径人工血管(直径>6 mm)已成功应用于临床,小口径人工血管(直径<6 mm)由于血栓形成、内膜增生、炎症反应和顺应性差导致血流动力学改变等原因,使其移植后远期通畅率低,距离临床应用尚有一段距离。其中,快速内皮化、抑制血栓形成及与自体血管相匹配的顺应性仍是解决问题的关键。本文简述制备小口径人工血管常用材料及技术的特点,重点讨论提高人工血管生物相容性和顺应性的策略,并对未来的研究工作进行展望。

盐雾环境对典型步枪自动机运动影响

盐雾环境对自动步枪战术技术性能和作战效能有着重要影响,但目前对盐雾环境对自动机运动特性和故障的影响机理尚不明确。以某小口径自动步枪为试验对象,设计并进行盐雾全寿命试验,在每次盐雾后通过高速摄影非接触测量自动机运动、高精度天平测量枪机框质量、簧力测试仪测量复进簧参数;对枪机框及导轨表面形貌特征进行拍照,统计全寿命过程中故障情况,获得自动机运动典型故障类型。研究结果表明:随着盐雾时间增长,枪机框质量逐渐增加;复进簧自由长度及预压力逐渐减小,工作压力先减小、后趋于平缓;自动机后坐到位速度先减小、后增大;复进开始及复进到位速度逐渐减小,且二者具有相同变化趋势。盐雾使自动机后座到位速度减小,自动机运动故障次数增多,盐雾环境引起的多参数变化对自动机故障频次影响明显。在试验研究的基础上,构建枪机框质量、复进簧参数、特征点速度随时间变化定量关系公式,为推断盐雾环境自动机运动件参数变化状况和分析其对故障的影响提供参考依据。

蚕丝基小口径人工血管研究进展

心血管疾病居全球死亡率首位,其中冠状动脉和周边堵塞性血管疾病威胁巨大。为了降低该疾病对人类生命的严重威胁,小口径人工血管移植术(搭桥)是较为普遍的治疗手段,但目前常用的制备方法和材料存在长期通畅率低、易形成血栓和难以在体内促进血管内皮化等问题。桑蚕丝因具备良好的力学性能、生物相容性及可控的生物降解性而被广泛用于小口径人工血管。本文综述了蚕丝基小口径人工血管在动物体内的应用,总结了以蚕丝基为材料制备小口径血管的优势,分析了存在的缺陷和改进方向,以期为蚕丝基小口径人工血管的研究发展提供参考。

25 mm口径引信高过载条件下强度有限元分析

针对小口径引信的强度安全性问题,完成了高过载条件下引信零部件的强度有限元分析。完成了某型25 mm小口径引信的三维建模、工作原理及其受力情况分析;为实现引信关键零部件的强度有限元分析,确定了引信零部件的材料属性并对模型进行简化。利用Hyper Mesh进行网格划分、连接关系设置和高过载工作环境(后座过载70000 g和转速过载30000 r/min)搭建。通过有限元计算获得了引信零部件在高过载条件下的应力分布情况、变形情况,仿真分析发现压板和底座所承受的应力最大,分别为87.69 MPa和292.51 MPa。在转速载荷加载时,隔爆机构解除保险,离心转子在离心力的作用下转动44.395°,使传火孔与击针对正,保证了引信的正常工作,引信零部件的强度满足发射安全性要求。

负载铜复合物小口径人工血管材料的构建及其生物功能评价

目的构建负载内源性一氧化氮供体催化剂铜复合物的纳米纤维小口径人工血管材料,评价其生物功能。方法合成催化体内一氧化氮供体释放一氧化氮的铜离子复合物(Cu(Ⅱ)-DTTCT)。用Cu(Ⅱ)-DTTCT和具有良好生物相容性的高分子聚合物——聚己内酯(PCL)为原材料,精确催化剂用量,同轴电纺方式制备小口径人工血管支架材料。对其进行一氧化氮释放量、铜离子复合物包载率以及细胞毒性的测定。采用SD大鼠作为半体外和体内评估载体。应用动静脉分流、植入材料原位移植术、活体超声检测、体式显微镜和扫描电镜观察、HE染色等技术评价其生物功能。结果构建以催化剂Cu(Ⅱ)-DTTCT和PCL为芯,以PCL为壳的具有芯壳结构的小口径人工血管支架材料PCL&Cu(Ⅱ)-DTTCT。PCL&Cu(Ⅱ)-DTTCT在所检测时间没有出现一氧化氮明显突释现象。铜离子复合物包载率为91.60%;PCL&Cu(Ⅱ)-DTTCT纤维薄膜的细胞毒性与对照组(PCL)相比几乎没有明显差异。半体外行动静脉分流实验1 h后,体视显微镜下对照组PCL材料内壁见沉积和血小板黏附现象,实验组PCL&Cu(Ⅱ)-DTTCT材料内壁相对干净光滑,没有明显血栓;扫描电镜下观察,对照组PCL见大量血小板黏附,实验组PCL&Cu(Ⅱ)-DTTCT材料上血小板很少,清晰可见人工血管纤维结构;PCL对照组和PCL&Cu(Ⅱ)-DTTCT实验组在行人工血管原位移植术2周、1个月、3个月、6个月后,用超声检测移入血管均通畅,均无因血管阻塞死亡情况;1个月后活体取材后体视显微镜下实验组PCL&Cu(Ⅱ)-DTTC管壁均匀,内腔干净,没有明显的血栓,对照组由于红细胞的浸润表面出现了一些微血栓;扫描电镜观察可见,两组管腔表面已被完全的覆盖,PCL对照组可见血小板,PCL&Cu(Ⅱ)-DTTCT实验组未见明显血小板影像;通过HE染色来分析血管支架的组织再生情况,对照组和实验组血管支架内腔可以观察到一层再生组织,实验组新生组织的厚度明显高于对照组。实验组有核细胞黏附高于对照组。结论构建的负载内源性一氧化氮供体催化剂铜复合物的纳米纤维小口径人工血管材料PCL&Cu(Ⅱ)-DTTCT,可以促使一氧化氮持续释放,发挥抑制血小板黏附的生理功能,抑制血栓的形成和早期再狭窄的发生,在早期促进组织再生。

微小口径涡街流量计设计与测量特性研究

涡街流量计是基于流体振荡原理对流量进行测量的流量计,但在低流速下输出的信号很微弱,在实际测量过程中会叠加各种现场产生的噪音。并且目前工业上使用小口径涡街流量计在小流量工况下存在测量局限性,一般最小口径仅到DN15。针对目前涡街流量计存在的问题对DN10及以下的微小口径涡街流量计结构及参数进行研究,以满足工业上的测量新需求。基于模拟仿真计算平台,建立不同尺寸参数的微小口径涡街流量计数值计算模型并进行仿真计算,提出优化的涡街流量计结构尺寸。通过对不同压力监测点的压力波动强度及频率的研究,分析传感器的最佳布置位置。最后以电磁流量计为标准表对所研制的微小口径涡街流量计在微量程段进行了测试,对该被检流量计的误差、精度等参数进行实验,同时对雷诺数与斯特劳哈尔数之间的关系及仪表系数进行分析,结果表明,仿真所获的测量特性与实验测得的特性具有较好的一致性,且该微小口径涡街流量计相对误差优于0.5%,重复性等指标能够满足微量程段内的测量标准。

双环境力耦合作用下小口径弹药引信火工品装药的力学响应

为探究轴向过载和由高转速引起的离心过载耦合作用下小口径弹药引信火工品装药的力学响应,采用ANSYS软件对实际发射情况和简化情况下药剂最大等效应力和最大静水压力的变化进行了数值模拟研究。结果表明,采用静态等效方法分析时,离心过载对药剂最大等效应力影响很小,基本可以忽略不计,但其对最大静水压力有一定影响;当药剂处于弹性变形阶段时,其最大等效应力基本由最大轴向过载决定,而由高转速产生的离心过载和轴向过载曲线周期对最大等效应力的影响很小;最大等效应力、最大静水压力均与最大轴向过载呈明显的线性关系。