Technique for Estimating the Cone Bearing Smoothing Parameters

Cone penetration testing (CPT) is an extensively utilized and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic cone into penetrable soils and recording the resistance to the cone tip (qc value). The measured qc values (after correction for the pore water pressure) are utilized to estimate soil type and associated soil properties based predominantly on empirical correlations. The most common cone tips have associated areas of 10 cm2 and 15 cm2. Investigators also utilized significantly larger cone tips (33 cm2 and 40 cm2) so that gravelly soils can be penetrated. Small cone tips (2 cm2 and 5 cm2) are utilized for shallow soil investigations. The cone tip resistance measured at a particular depth is affected by the values above and below the depth of interest which results in a smoothing or blurring of the true bearing values. Extensive work has been carried out in mathematically modelling the smoothing function which results in the blurred cone bearing measurements. This paper outlines a technique which facilitates estimating the dominant parameters of the cone smoothing function from processing real cone bearing data sets. This cone calibration technique is referred to as the so-called CPSPE algorithm. The mathematical details of the CPSPE algorithm are outlined in this paper along with the results from a challenging test bed simulation.

上颌前牙区多生牙的锥形束CT影像学特征研究

目的 利用锥形束CT(cone beam computed tomography,CBCT)分析上颌前牙区多生牙(supernumerary tooth,ST)的影像学特征,为ST的治疗提供帮助。方法 共收集805例CBCT数据,利用专用软件NNT评价ST的影像学特征,包括:数目、形态、位置、方向、发育情况和并发症,并分析上述影像学特征的性别差异。结果 男女比例2.96∶1,男性和女性ST均以单枚、锥形、牙弓腭侧、倒置和阻生为主,但男性发生2枚ST的比例显著高于女性(P<0.001),女性ST倒置的比例更高(P<0.001)。最常见的ST相关的并发症是鼻腭管管壁骨质吸收,且男性高于女性(P=0.01)。此外,ST累及解剖结构及相关临床并发症还包括鼻底骨质吸收,形成颌骨囊肿,牙滤泡间隙增宽,邻牙阻生、移位或扭转、根吸收。结论 男性和女性上颌前牙区的ST以单枚、锥形、牙弓腭侧、倒置和阻生为主,但发病特点存在性别差异。ST可导致多种并发症,CBCT的准确分析有助于ST的诊断和治疗。

Cone Bearing Estimation Utilizing a Hybrid HMM and IFM Smoother Filter Formulation

Cone penetration testing (CPT) is a widely used geotechnical engineering in-situ test for mapping soil profiles and assessing soil properties. In CPT, a cone on the end of a series of rods is pushed into the ground at a constant rate and resistance to the cone tip is measured (qm). The qm values are utilized to characterize the soil profile. Unfortunately, the measured cone tip resistance is blurred and/or averaged which can result in the distortion of the soil profile characterization and the inability to identify thin layers. This paper outlines a novel and highly effective algorithm for obtaining cone bearing estimates qt from averaged or smoothed qm measurements. This qt optimal filter estimation technique is referred to as the qtHMM-IFM algorithm and it implements a hybrid hidden Markov model and iterative forward modelling technique. The mathematical details of the qtHMM-IFM algorithm are outlined in this paper along with the results from challenging test bed. The test bed simulations have demonstrated that the qtHMM-IFM algorithm can derive accurate qt values from challenging averaged qm profiles. This allows for greater soil resolution and the identification and quantification of thin layers in a soil profile.

Methodology for Obtaining Optimal Sleeve Friction and Friction Ratio Estimates from CPT Data

Cone penetration testing (CPT) is a cost effective and popular tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic penetrometer into penetrable soils and recording cone bearing (qc), sleeve friction (fc) and dynamic pore pressure (u) with depth. The measured qc, fs and u values are utilized to estimate soil type and associated soil properties. A popular method to estimate soil type from CPT measurements is the Soil Behavior Type (SBT) chart. The SBT plots cone resistance vs friction ratio, Rf [where: Rf = (fs/qc)100%]. There are distortions in the CPT measurements which can result in erroneous SBT plots. Cone bearing measurements at a specific depth are blurred or averaged due to qc values being strongly influenced by soils within 10 to 30 cone diameters from the cone tip. The qcHMM algorithm was developed to address the qc blurring/averaging limitation. This paper describes the distortions which occur when obtaining sleeve friction measurements which can in association with qc blurring result in significant errors in the calculated Rf values. This paper outlines a novel and highly effective algorithm for obtaining accurate sleeve friction and friction ratio estimates. The fc optimal filter estimation technique is referred to as the OSFE-IFM algorithm. The mathematical details of the OSFE-IFM algorithm are outlined in this paper along with the results from a challenging test bed simulation. The test bed simulation demonstrates that the OSFE-IFM algorithm derives accurate estimates of sleeve friction from measured values. Optimal estimates of cone bearing and sleeve friction result in accurate Rf values and subsequent accurate estimates of soil behavior type.

向量优化问题最优性条件的锥刻画

研究实Banach空间中带有不等式约束的非光滑向量优化问题(VP).利用不同锥分别在目标函数的像空间和决策空间中研究了它的各种有效解的必要条件.

几种真有效点的锥刻画

本文在一般向量优化问题的目标空间中研究几种真有效点的锥刻画。设Y是偏序局部凸Hausdorff拓扑向量空间,Y*为其拓扑对偶空间,C是空间Y的序锥,D是Y中的一个凸子集,点y∈D。首先,笔者用切向锥TD(y)与负序锥-C或-C\(0)间的位置关系式来给出y是D的Benson真有效点(超有效点、强有效点和两种严有效点)的充分必要条件;利用这些结果,得到了这几种真有效点概念等价的一个充分条件。然后,在对偶空间Y*中,用法向锥ND(y)与锥C-i或-int(C-)间的位置关系式来给出y是D的Benson真有效点(强有效点)的充分必要条件。

向量优化问题真有效点的锥刻画

在向量优化问题中最佳目标值的存在性与求解始终是研究的核心问题,其实质是在目标函数的可行域中寻找使目标值在一定意义下的最佳点,而有效点、弱有效点和真有效点正是表征了点在集合中的某种最佳性。在一般向量优化问题的目标空间中研究了2种真有效点-Henig真有效点和Hurwicz真有效点的锥刻画。主要利用集合在某点的相依锥、法向锥和可行方向锥对向量优化问题的真有效点的特征进行了刻画。首先,利用切向锥与负序锥的位置关系式来给出成为Henig真有效点和Hurwicz真有效点的充分必要条件。然后,利用这些结果,得到了这2种真有效点概念等价的一个充分条件。最后,在对偶空间中,用法向锥与锥间的位置关系式来给出是成为凸子集中Henig真有效点的充分必要条件。

获取材料本构关系和硬度的压入法研究

依据锥形压入试验和弹塑性接触有限元分析,提出基于能量原理预测金属材料本构关系的CR-EMI方法。通过该方法揭示锥形压入能量比与表征应力之间存在线性律,提出通过压入曲线(P-h曲线)获取材料本构关系的关系式,根据Hollomon本构关系模型预测硬度的H-EMI方法。通过对多种金属材料进行压入试验和有限元分析,验证CR-EMI方法和H-EMI方法的有效性与精确性。

氯化亚锡对阻燃体系复合酚醛泡沫性能的影响

以多聚磷酸铵、季戊四醇、氯化亚锡为原料组成膨胀型阻燃系统，研究氯化亚锡添加量对膨胀型阻燃系统复合酚醛泡沫的极限氧指数、燃烧热量释放速率、燃烧总热释放量、有效燃烧热量、耗氧量、烟气释放、有毒气体释放等的影响。研究结果表明阻燃体系复合泡沫的极限氧指数在72．8％～74．5％之间，展现出良好的阻燃性，阻燃体系对酚醛泡沫的阻燃符合气相阻燃的机理，并且在氯化亚锡添加量为1．5％时，阻燃体系复合泡沫的阻燃性能最优。

基于原位测试指标的砂土时间效应定量表征初步研究

时间效应对土体抗液化强度有显著影响,其定量表征是砂土地震液化判别的研究难点之一。基于土体小应变剪切模量Gmax和静力触探锥尖阻力qc的经验表达式,对土体密实度和有效应力作归一化处理,提出了砂土时间效应的表征指标AI。该表征指标在数学上表达为小应变剪切模量与大应变静力触探锥尖阻力的结构性参数的比值函数。通过分析已有室内试验数据发现重塑砂土具有稳定的AI值,而对现场数据的分析则揭示了砂土沉积年代越久、AI值越大的整体趋势。该表征指标能揭示土体力学特性随时间的演变规律却不含时间变量,因此是一个"表观时间"参数,为进一步研究时间效应对砂土抗液化强度的影响规律提供了基础。

Self-Adaptive Grinding for Blind Tip Reconstruction of AFM Diamond Probe

Blind tip reconstruction(BTR) method is one of the favorable methods to estimate the atomic force microscopy(AFM) probe shape. The exact shape of the characterizer is not required for BTR, while the geometry of the sample may affect the reconstruction significantly. A cone-shaped array sample was chosen as a characterizer to be evaluated. The target AFM probe to be reconstructed was a diamond triangular pyramid probe with two feature angles, namely front angle(FA) and back angle(BA). Four conical structures with different semi-angles were dilated by the pyramid probe. Simulation of scanning process demonstrates that it is easy to judge from the images of the isolated rotary structure, cone-shaped, the suitability of the sample to be a tip characterizer for a pyramid probe. The cone-shaped array sample was repeatedly scanned 50 times by the diamond probe using an AFM. The series of scanning images shrank gradually and more information of the probe was exhibited in the images, indicating that the characterizer has been more suitable for BTR. The feature angle FA of the characterizer increasingly reduces during the scanning process. A self-adaptive grinding between the probe and the characterizer contributes to BTR of the diamond pyramid probe.

阻燃材料测试与表征方法简述

本文简单介绍了几种常用的阻燃材料测试和表征方法。随着阻燃科学的发展,出现了新一代的阻燃测试仪器一锥形量热仪,它能够较好地评价阻燃材料的真实燃烧行为。同时,多种测试方法的结合使用可以更为准确地评价材料的阻燃性能及分析其阻燃机理。

三氧化钼对无卤阻燃复合酚醛泡沫体系性能的影响

以多聚磷酸铵、季戊四醇、三氧化钼(Mo O3)组成无卤协同阻燃体系,研究了Mo O3不同添加量对阻燃体系复合酚醛泡沫的热释放性能、发烟性能及力学性能等的影响。研究结果表明:与纯酚醛泡沫相比,阻燃体系复合酚醛泡沫的极限氧指数(ILO)均值升高了约73%;900℃时的残炭量在Mo O3添加量≤1.5%时略有增加,而后有所降低;热释放速率(HRR)、总热释放量(THR)、氧气消耗量(O2C)、一氧化碳(COP)和二氧化碳产量(CO2P)的均值分别降低了约75%、68%、68%、28%和41%,总烟释放(TSR)均值上升了约72%;从比消光面积(SEA)显著升高和有效燃烧热(EHC)显著降低可知,阻燃体系符合气相阻燃的机理;复合酚醛泡沫的弯曲和压缩强度均值分别降低了约29%和19%。综合分析可知,Mo O3添加量为1.5%时,阻燃体系复合酚醛泡沫的综合性能最优。

三维六向锥管形预制件细观结构研究

研究了逐步全减细纤维束工艺,并利用该工艺实现了三维六向锥管形预制件的制备。通过分析纤维束的运动走向和位置分布,获得了锥管形预制件的6种单胞;根据不同单胞结构,将预制件分为5个区域,针对5个分区的不同单胞,逐一构建几何模型,从而得到各部分纤维束在单胞中的排列与分布规律,可视化地表征了逐步全减细纤维束预制件的内部细观结构。研究成果为预制件几何尺寸和纤维体积百分含量的计算奠定了基础,同时为三维六向锥管形预制件的研发提供了理论指导。

卷烟燃烧过程中烟丝形态结构变化的表征方法

为了研究卷烟燃烧过程中烟丝形态结构变化对烟气释放的影响,从烟丝的微观结构、燃烧锥平面结构等方面,建立了表征卷烟燃吸过程中烟丝形态结构变化的新方法,并探讨了卷烟燃吸过程中烟丝形态结构变化对主流烟气CO释放量的影响。结果表明:(1)烟丝形态结构发生变化的特征温度为300~350℃。在该温度区间内,烟丝的宽度和厚度均出现了显著的收缩,同时烟丝整体发生卷曲;(2)通过对包埋固定后的燃烧锥进行切片,获得了燃烧锥长度及面孔率等燃烧锥结构的表征参数;(3)烟丝宽度从0.6 mm增至1.4 mm,卷烟燃烧锥长度变短,面孔率增加,单位质量烟丝的CO释放量降低17.42%;(4)烟丝长度从大于4.0 mm降低至小于1.6 mm,卷烟燃烧锥长度变短,面孔率增加,单位质量烟丝的CO释放量降低16.73%。

多目标优化问题近似解的最优性条件

研究了多目标优化问题的一类近似有效解、近似弱有效解和近似真有效解,并利用切锥、可行方向锥、ε-法锥等几何概念刻画了近似解的必要性及充分性条件.

阻燃材料测试与表征方法概述

介绍几种常用的阻燃材料测试方法,包括水平和垂直燃烧法、氧指数法、NBS烟箱法、热分析法、锥形量热仪法,重点介绍了锥形量热仪法及其在阻燃材料研究中的应用。指出将多种测试方法结合使用可以更好地评价材料的阻燃性能。

一种基于CPT实测值预测地基处理工后沉降的理论计算方法

提供一种采用场地地基处理后的CPT实测值来预测堆场的工后沉降进而验证场地地基处理效果的方法。该计算方法可通过CPT实测值将土层划分出黏性土层和砂性土层,并针对不同的土层采用不同的沉降计算公式。在此基础之上,提供了一种针对大面积堆载和独立基础荷载沉降预测的计算方法,并对某港口集装箱区进行了沉降预测。该方法仅通过静力触探试验和固结试验即可获得计算参数,实用性较强,已成功运用于国外某大型集装箱码头堆场地基处理设计中。

几种多重线性约束逼近的特征问题

本文讨论了用一族线性约束多项式集合的交逼近函数 f 时的特征问题。特别,用局部凸锥形的多项式集合及多重约束导数值域多项式的集合作一致逼近时,我们获得了明确的结果。

Haar锥逼近的交错定理及其在系数有界逼近中的应用(英文)

本文首先推广了 P.Peisker 1983年给出的Haar锥的定义及 Haar锥一致逼近的交错定理,然后得到了Haar锥根数的一种求法。利用这些结果,讨论了系数有界限逼近的特征问题,特别是给出了系数有界限的代数多项式逼近与广义Bernstein多项式逼近的使用十分方便的交错定理。