论齿轮样板

齿轮样板是齿轮参数量值的标准实物载体,用于将齿轮国家测量标准所复现的量值传递到各级齿轮测量仪器上,从而实现齿轮测量的准确性和一致性,保证齿轮产品质量。全面概述了齿轮样板起源及其发展历程;详细论述了齿轮样板的种类、结构及特点、齿轮样板的测量技术及装置、齿轮样板的国际比对、未来的发展与展望。齿轮样板迄今已历经九十多年发展,其种类在不断丰富、尺度不断延伸、复杂度不断简化,作为一种“有形”的实物量具,目前仍不可替代。未来随着“无形”的虚拟仿真测量技术发展,对“有形”实物样板的依赖将可以减弱,“无形”的技术将可能成为量值传递的新模式。

和胃解毒方对食管鳞癌同步放化疗病人血清肿瘤相关因子、免疫因子的影响

目的:研究和胃解毒方对食管鳞癌(ESC)同步放化疗(CRT)病人血清肿瘤相关因子、免疫因子及炎性因子的影响。方法:选取ESC同步放化疗病人84例,按照随机数字表法将病人分为观察组和对照组,各42例。对照组行CRT治疗,观察组行CRT联合和胃解毒方治疗。观察2组治疗前后血清细胞角蛋白19片段(CYFRA 21-1)、鳞状细胞癌抗原(SCC)、癌胚抗原(CEA)等肿瘤相关因子水平,血清CD3^(+)、CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+)等TBNK淋巴细胞亚群水平,血清白细胞介素(IL)-6、IL-8、肿瘤坏死因子-α(TNF-α)等炎性因子水平及中医症候积分。结果:治疗后,观察组血清CYFRA 21-1、SCC、CEA水平较对照组低(P<0.01),观察组CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)水平均较对照组高,CD8^(+)水平较对照组低(P<0.01)。观察组血清IL-6、IL-8、TNF-α水平明显较对照组低(P<0.01)。观察组中医症候积分较对照组低(P<0.01);结论:和胃解毒方应用于ESC CRT病人,可有效杀灭ESC细胞,降低肿瘤相关因子水平,改善免疫因子水平。

湖北杉木人工林生物量及其可变密度预估模型研究

利用6~59年生杉木人工林190个标准地资料和517株样木生物量测定数据,以建立的单木生物量估算方程为基础推算出各林分单位面积生物量,并基于林龄、立地指数以及7种不同林分密度指标构建并选择最优的全林分生物量预估方程,研究湖北杉木人工林林分生物量及其变化规律。结果表明:该区域杉木人工林平均单株生物量为52.8893 kg,以胸径和树高为变量的二元单木生物量方程的拟合优度为0.91,其拟合优度和精度更高;林分平均单位面积生物量为101.4923 t/hm^(2),总体上呈随林龄增加而增大的趋势;基于多元回归技术的经验方程构建了含7个林分密度指标和不含密度指标共计16种林分生物量预估模型,包含林分立木株数和林木大小信息的林分密度指标的模型均达到了较理想的拟合效果,其中密度指数SDI的Schumacher修正收获模型精度最高,确定系数为0.95,检验精度为97%,对本区域杉木生物量估算具有较好的适用性,能为其人工林经营和质量提升提供参考与支持。

转台负载工况下角位置误差补偿方法研究

负载会影响转台回转轴的运动状态,进一步影响转台角位置误差的大小。通过分析负载工况下转台角位置误差傅里叶阶次的变化情况,提出一种基于谐波补偿的误差补偿方法。首先,分析负载对转台回转轴的影响,建立回转轴误差运动与角位置误差之间的数学模型,并进行数值仿真;其次,通过负载变化影响回转轴误差运动的大小,获取转台不同负载下的自校准曲线,采用傅里叶法分析对负载变化敏感的傅里叶阶次;最后,选取对负载变化敏感的傅里叶阶次拟合谐波补偿函数对转台角位置误差进行补偿。误差补偿后转台在不同负载工况下的角位置误差最大为±0.25″,与补偿后空载工况下角位置误差相差±0.03″,有效减小了负载对转台角位置误差的影响。

4个柏木种源的抗寒性与抗旱性评价

以四川三台、湖北京山、重庆酉阳和浙江开化4个种源柏木的(Cupressus funebris)2年生实生苗为对象,分别进行了低温与干旱胁迫处理。通过观测表型以及测定针叶的相对和绝对含水量、相对电导率、光合色素含量、丙二醛含量、游离脯氨酸含量等指标,采用隶属函数分析法,对4个种源柏木的抗寒性与抗旱性进行了评价。结果表明:(1)低温胁迫下,随着温度的降低,所有种源植株的相对电导率明显上升;叶绿素含量显著降低,类胡卜素含量的变化趋势不明显;丙二醛和脯氨酸含量显著提高。4个种源对低温胁迫的响应和耐受程度有所不同,其抗寒性由强到弱排序为:浙江开化>四川三台>重庆酉阳>湖北京山。(2)干旱胁迫下,植株生长减缓,并出现明显失水症状。干旱30 d时,针叶的相对电导率和丙二醛含量明显上升,光合色素含量显著降低,复水10 d后均恢复至对照水平;脯氨酸含量亦显著增加,但复水后未达到对照处理水平。4个种源对干旱胁迫的响应和耐受程度亦明显不同,其抗旱性由强到弱排序为:重庆酉阳>四川三台>湖北京山>浙江开化。

基于地空激光雷达的池杉人工林林分空间结构优化

【目的】以池杉人工林为研究对象,融合地空激光雷达点云数据,评估林分空间结构特征,为池杉人工林质量提升和可持续经营提供科学依据和理论支持。【方法】以仙女林场2块30 m×30 m池杉样地的无人机激光雷达、地基激光雷达和野外实地调查数据为数据源,融合点云数据后进行单木分割和单木参数提取,选择角尺度、大小比数、空间密度指数、开敞度、生长空间指数、生长空间竞争指数、简单竞争指数等7个参数构建综合评价模型。通过综合评价模型进行模拟采伐,选取最优采伐强度,对林分空间结构优化策略进行评估。【结果】与实测数据对比,地空激光雷达的胸径和树高的提取精度R^(2)均值分别为0.9883、0.9853,均方根误差均值分别为0.4939 cm、0.1255 m;A、B样方的林分空间结构综合指数为0.526、0.349,通过模拟采伐选取的A、B两个样方的最优采伐强度分别为总蓄积6%、8%,该采伐强度能够在不过量采伐基础上,使林分空间结构综合指数分别上升0.067、0.132,有效地改善林分内树木的生长环境和降低资源竞争压力。【结论】利用地空激光雷达融合可高效实现林分结构信息的数字化、精细化,克服单一激光雷达和传统人工存在的局限性,对于人工林资源调查与监测具有重要的实际意义;利用综合评价模型对池杉人工林的空间结构进行综合评估和模拟采伐可以指导林分空间结构优化,为林分改造与森林质量提升提供科学依据和实践参考。

LiBF_(4)和LiDFOB双盐电解液实现硬碳负极的室温和低温电化学性能优化调控

为克服商用六氟磷酸锂(LiPF_6)基电解液无法使锂离子电池在0℃下正常工作的问题,开发低温锂离子电池电解液成为领域研究重点。其中,四氟硼酸锂(LiBF_(4))基电解液因其低温下电荷转移阻抗较小,二氟草酸硼酸锂(LiDFOB)基电解液因其良好的成膜性能都备受学者关注。开发了一种新型LiBF_(4)和LiDFOB双盐电解液,通过优化与调控,使硬碳负极在室温和低温条件下同时具有优异的电化学性能。通过循环伏安、倍率和循环性能测试,系统比较了LiBF_(4)和LiDFOB及其混合双盐电解液对硬碳负极室温及低温电化学性能的影响。结果表明:LiBF_(4)+LiDFOB双盐电解液在兼顾硬碳室温电化学性能的同时,仍能实现硬碳优异的低温循环性能,100圈循环后硬碳仍有134 mAh·g^(-1)的可逆容量,显著优于硬碳在商用LiPF_6基电解液中的循环性能(100圈循环后可逆容量仅为2 mAh·g^(-1))。

Efficient removal of U(VI) from wastewater by a sponge-like 3D porous architecture with hybrid electrospun nanofibers

Removal of uranium(VI)from nuclear wastewater is urgent due to the global nuclear energy exploitation.This study synthesized novel sponge-like 3D porous materials for enhanced uranium adsorption by combining electrospinning and fibrous freeze-shaping techniques.The materials possessed an organic-inorganic hybrid architecture based on the electrospun fibers of polyacrylonitrile(PAN)and SiO_(2).As a sup-porting material,the surface of fibrous SiO_(2) could be further functionalized by cyano groups via(3-cyanopropyl)triethoxysilane.All the cyano groups were turned into amidoxime(AO)groups to obtain a amidoxime-functionalized sponge(PAO/SiO_(2)-AO)through the subsequent ami-doximation process.The proposed sponge exhibited enhanced uranium adsorption performance with a high removal capacity of 367.12 mg/g,a large adsorption coefficient of 4.0×10^(4)mL/g,and a high removal efficiency of 97.59%.The UO_(2)^(2+)adsorption kinetics perfectly conformed to the pseudo-second-order reaction.The sorbent also exhibited an excellent selectivity for UO_(2)^(2+) with other interfering metal ions.2023 Hohai University.Production and hosting by Elsevier B.V.

车载毫米波雷达BSD功能系统的应用与设计

毫米波雷达BSD系统是一种将双角雷达置于车身2个尾角进行盲区监测和目标感知的高级辅助驾驶方案,是一种低成本的自动泊车以及变道辅助方案。本文设计一种BSD控制策略,在实车道路测试中得到可靠的验证,网络通信设计基于CAN总线对此雷达BSD系统进行整车通信和交互设计。

Clinical significance of expression of proliferating cell nuclear antigen and E-cadherin in gastric carcinoma

AIM to investigate the expression of proliferating cell nuclear antigen(p CNA)and E-cadherin in gastric carcinoma and to analyze their clinical significance.METHODS A total of 146 patients were selected for this study,including 38 patients with intestinal metaplasia,42with dysplasia,and 66 with primary gastric cancer.In addition,40 patients with normal gastric tissues were selected as controls.the expression of p CNA and E-cadherin was detected by immunohistochemistry.Differences in p CNA and the E-cadherin labeling indexes among normal gastric mucosa,intestinal metaplasia,dysplasia,and gastric carcinoma were compared.Subjects with normal gastric tissues were assigned to a normal group,while gastric cancer patients were assigned to a gastric cancer group.the difference in p CNA and E-cadherin expression between these two groups was compared.the relationship between expression of p CNA and E-cadherin and clinicopathological features was also explored in gastric cancer patients.furthermore,prognosis-related factors,as well as the expression of p CNA and E-cadherin,were analyzed in patients with gastric cancer to determine the 3-year survival of these patients.RESULTS the difference in p CNA and the E-cadherin labeling indexes among normal gastric mucosa,intestinal metaplasia,dysplasia,and gastric carcinoma was statistically significant(p<0.05).During the transition of normal gastric mucosa to gastric cancer,the p CNA labeling index gradually increased,while the E-cadherin labeling index gradually decreased(p<0.05).the p CNA labeling index was significantly higher and the E-cadherin labeling index was significantly lower in gastric cancer than in dysplasia(p<0.05).the expression of p CNA was significantly higher in the gastric cancer group than in the normal group,but E-cadherin was weaker(p<0.05).there was a negative correlation between the expression of p CNA and E-cadherin in gastric carcinoma(r=-0.741,p=0.000).p CNA expression differed significantly between gastric cancer patients with and without lymph node metastasis and between patients at different t stages.E-cadherin expression also differed significantly between gastric cancer patients with and without lymph node metastasis(p<0.05).High t stage and positive p CNA expression were risk factors for the prognosis of patients with gastric cancer(RR>1),while the positive expression of E-cadherin was a protective factor(RR<1).the sensitivity,specificity,and accuracy of p CNA positivity in predicting the 3-year survival of patients with gastric cancer were 93.33%,38.89%,and0.64,respectively;while these values for E-cadherin negativity were 80.0%,41.67%,and 0.59,respectively.When p CNA positivity and E-cadherin negativity were combined,the sensitivity,specificity,and accuracy were66.67%,66.67%,and 0.67,respectively.CONCLUSION Combined detection of p CNA and E-cadherin can improve the accuracy of assessing the prognosis of patients with gastric cancer.

Permanence and Global Stability for a Non-Autonomous Predator-Prey Model with Modified Leslie-Gower and Holling-Type II Schemes with Delays

In this paper, a nonautonomous predator-prey system based on a modified version of the Leslie-Gower scheme and Holling-type II scheme with delayed effect is investigated. The general criteria of integrable form on the permanence are established. By constructing suitable Lyapunov functionals, a set of easily verifiable sufficient conditions are derived for global stability of any positive solutions to the

Study on rolling process optimization of high carbon steel wire

The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experimental parameters for thermal simulation were optimized, and the thermal simulating experiments were carded out on a Gleeblel500 thermal simulator. The process parameters for the manufacture were optimized after analysis of the data, and the productive experiments were performed after the water box in front of the no-twist blocks was reconstructed, to control the temperature of the loop layer. The results from the productive experiments showed that the cooling rate of 10-15℃/s was reasonable before phase transformation, about 5℃/s during phase transformation, and 600-620℃ was the suitable starting temperature for phase transformation. The ultimate strength of the Ф11.0 mm wire was increased to 1150-1170 MPa with an increase of 20-30 MPa, the percentage reduction of section was to 34%-36% with an increase of 1%-3% by testing the finished products after reconstruction.

Challenges and Methods to Improve Well Cementing Quality for 177.8 mm Liner in Gaoshiti-Moxi Area

Gaoshiti-Moxi structure belt of An-Yue Sinian gas reservoir, which was China’s largest monomer Marine carbonate gas reservoir up to now, located in vying-dragon female temple structure group that belong to the ancient uplift slope of the middle of Sichuan. With the exploration and development of high temperature and high pressure carbonate reservoir, a large number of challenges and problems, such as long isolation section, active oil-gas show, large temperature difference, prone to super retarding cement slurry and gas channeling at flare position, have been encountered in the cementing of 177.8 mm hang-liner. In order to solve these problems, numerous measures and methods have been put into use for reducing the safety risk of cementing and improving cementing quality. The large temperature difference channeling cement slurry system, effective anti-pollution spacer and high-pressure packer type liner hanger were developed and applied for field tests in the early stage of development. In addition, equilibrium pressure cementing technology, optimizing of centralizer placement and plasma column structure, improvement of pump displacement and hold pressure while waiting on cement were used to ensure nice displacement efficiency and cementing quality. As Moxi X well for example, the cementing quality factor of merit was 40.29% and the qualification rate was up to 78.87% after adopting the cementing measures and methods above. The cementing quality was much higher than previous level and provided technical support for Gaoshiti-Moxi area.

高精度齿轮渐开线样板与测量仪器研究进展

渐开线圆柱齿轮是量大面广的关键机械基础件,为了实现渐开线量值的统一,通常需要将渐开线样板作为渐开线的实体标准器进行渐开线齿廓偏差的量值溯源、量值传递与量值比对。本文回顾了各国高精度单基圆参数、多基圆参数渐开线样板、集成其他几何参数的齿轮样板、非渐开线式样板及高精度渐开线测量仪器的研究进展,并对渐开线样板的使用展开长度提出了建议,对高精度渐开线样板的发展做出了展望。

林分密度对柏木人工林土壤养分及酶活性的影响

【目的】探索不同密度柏木(Cupressus funebris)人工林土壤养分含量及酶活性的变化趋势及其特征。【方法】以35~55年生柏木人工林为对象,研究不同林分密度(密度分别为4160、992、452株/公顷)下0~40 cm土层的土壤养分含量及酶活性变化。【结果】柏木人工林土壤养分含量及酶活性均随土层深度的增加呈降低趋势,具有明显的表聚现象。随着林分密度的降低,土壤养分含量呈先降低后增加的趋势,土壤全氮、全磷、全钾、碱解氮、速效钾在452株/公顷林分密度下含量最高;磷酸酶和蔗糖酶活性整体呈增加的趋势,且在452株/公顷林分密度下活性最大。相关分析结果显示:蔗糖酶、磷酸酶与土壤养分指标关系密切。【结论】适宜的林分密度有利于柏木人工林土壤养分的积累,能有效提高土壤肥力。

人工林土壤碳的影响途径研究进展

人工林已成为森林资源的关键组成部分和巨大的陆地碳储库,在土壤碳固存中发挥着重要作用。随着全球气候变化加剧,有关人工林土壤碳固存的研究愈发成为关注焦点。因此,综合探讨人工林土壤碳的影响途径可为其生态恢复和经营模式提供基础理论依据,对未来应对全球气候变化提供参考,在实现森林永续利用、维护生态系统平衡方面具有重要意义。本文综述了造林树种选择、植被和根系凋落物分解、土壤呼吸、土壤微生物活动、人为扰动对人工林土壤碳固存的影响,总结了当前诸多研究中有关土壤碳周转的侧重点,梳理了相关研究中存在的矛盾性观点,并对以后有关人工林土壤碳的研究作出展望:1)应加深多种生态环境途径综合作用的研究。2)拓展对不同尺度人工林土壤碳的探索。3)重视土壤微生物−土壤理化性质−植被根系之间的互作关系。4)构建更精确的人工林经营措施体系。5)建立对人工林土壤碳的长期动态监测网络。6)细化对人工林土壤碳组分的研究。

变法、党争与士大夫政治——王夫之的政治理论

王夫之在《宋论》中认为,维持良好政治风气的关键,是避免出现党争。一旦形成党争,君子也罢,小人也罢,都会意气用事,置国计民生于不顾,政治将成为泄愤工具,走向非理性的极化,国家也就随之崩溃。而要避免党争,关键是杜绝体制外的声音。尽管开国体制不可避免会丧失活力,但通过人事变更,上行下效,就能够带动体制自我更新。士大夫政治鼓励体制外发声,不仅会引发无谓甚至有害的变法,而且会催生党争。

Hepatitis B virus X protein-mediated upregulation of miR-221 activates the CXCL12-CXCR4 axis to promote NKT cells in HBVrelated hepatocellular carcinoma

Both hepatitis B virus X protein(HBx)and microRNA-221(miR-221)have been implicated in the development of hepatitis B virus(HBV)-related hepatocellular carcinoma(HCC).The present study demonstrates that HBx promotes HCC cell proliferation via the C-X-C motif chemokine ligand 12-C-X-C chemokine receptor type 4(CXCL12-CXCR4)axis.We predict that HBx/miR-221-mediated CXCL12/CXCR4 signaling induces NKT cells to promote HBV-related HCC.Methods:After miR-221 mimic,miR-221 mimic negative control,miR-221 inhibitor,miR-221 inhibitor negative control were transfected into cells,the expression of CXCL12 and miR-221 was detected by qPCR and western blot.Then we constructed a stable HBV-HCC cell line.HBV-HCC cells were injected into the nude mice,thus a HBV-HCC mouse model was constructed.Q-PCR and western blot were used to detect the expression of HBx,miR-221,CXCL12 and CXCR4 in tumor tissues.The expression of CXCL12 was detected by immunohistochemistry,and the expression of CXCR4,CD3 and CD56 was detected by immunofluorescence.The levels of CXCL12,IL-2 and TNF-αin serum of mice were detected by ELISA.Sixty-one patients with HBV-related HCC,61 patients with HBV-related cirrhosis,61 patients with chronic hepatitis B(CHB)and 30 healthy people were enrolled.CXCL12,cytokine levels,and clinicopathological parameters were tested.Results:Hepatitis B virus X protein upregulates the expression of miR-221 and CXCL12 in lentivirus(LV5)-HBx-transfected HepG2 cells.HBx protein promotes HepG2 cell proliferation in vitro.HBx protein promoted tumor growth via the miR-221/CXCL12/CXCR4 pathway in a mouse tumor model.HBx protein upregulated natural killer T cell expression via the CXCR4/CXCL12 pathway to promote tumor growth.The data demonstrated a positive correlation between CXCL12 concentration with Cre levels and Child-Pugh scores.CXCL12 had an inferior diagnostic efficiency compared to IL-2 and IL-6 for HBV-related HCC.Conclusions:We present evidence that HBx/miR-221-mediated CXCL12/CXCR4 signaling induces NKT cells to promote HBV-related HCC.

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