Using portable falling weight deflectometer to determine treatment depth of subgrades in highway reconstruction of Southern China

Based on a highway reconstruction project in southern China,this study aims to put forward a method to determine the proper treatment depth of the existing subgrade.First,some field tests including the Beckman beam deflection test and portable falling weight deflectometer(PFWD)test were carried out.The results showed that there was a good correlation between the Beckman beam deflection(L)and PFWD modulus(Ep).Subsequently,a subgrade section was excavated and backfilled with cement-stabilized soil in layers.Compaction test,dynamic cone penetrometer rate test,plate load test and Beckman beam deflection test were performed to evaluate the treatment effect.To make sure,the subgrade was treated deeply enough,the Beckman beam deflection(L)was used as the controlled indicator among all the measured indexes for it was the hardest metric to meet.According to the design deflection and decreasing law of the measured deflections with the different number of the stabilized layers,the treatment depth was finally determined.As the PFWD test is superior to the deflection test in the detection efficiency,and the deflection value can be calculated from PFWD modulus by correlation formulas,thus the latter index can be used as a more suitable parameter for estimating the treatment depth instead of the former.Consequently,based on the measured PFWD moduli of the existing subgrade,six treatment schemes considering different treatment depths were proposed.It was confirmed that the method developed from this study is feasible and worth being extensively applied.

Coin-structured tunable beam shaping assembly design for accelerator-based boron neutron capture therapy for tumors at different depths and sizes

In the past decade,boron neutron capture therapy utilizing an accelerator-based neutron source(ABNS)designed primarily for producing epithermal neutrons has been implemented in the treatment of brain tumors and other cancers.The specifications for designing an epithermal beam are primarily based on the IAEA-TECODC-1223 report,issued in 2001 for reactor neutron sources.Based on this report,the latest perspectives and clinical requirements,we designed an ABNS capable of adjusting the average neutron beam energy.The design was based on a 2.8 MeV,20 mA proton beam bombarding a lithium target to produce neutrons that were subsequently moderated and tuned through a tunable beam shaping assembly(BSA)which can modify the thicknesses and materials of the coin-shaped moderators,back reflectors,filters,and collimators.The simulation results demonstrated that epithermal neutron beams for deep seated tumor treatment,which were generated by utilizing magnesium fluoride with lengths ranging between 28 and 36 cm as the moderator,possessed a treatment depth of 5.6 cm although the neutron flux peak shifts from 4.5 to 1.0 keV.When utilizing a thinner moderator,a less accelerated beam power can meet the treatment requirements.However,higher powers reduced the treatment time.In contrast,employing a thick moderator can reduce the skin dose.In scenarios that required relatively low energy neutron beams,the removal of the thermal neutron filter can raise the thermal neutron flux at the beam port.And the depth of the dose rate peak could be adjusted between 0.25 and 2.20 cm by combining magnesium fluoride and polyethylene coins of different thicknesses.Hence,this device has a better adaptability for the treatment of superficial tumors.Overall,the tunable BSA provides greater flexibility for clinical treatment than common BSA designs that can only adjust the port size.

Effects of Laser Hardening Process Parameters on Case Depth of 4340 Steel Cylindrical Specimen—A Statistical Analysis

Laser heat treatment is considered to be one of best-performing manufacturing processes used currently due to its flexibility and its ability to develop parts with complex geometries. In fact, this process is able to produce reliable parts with hard, thin martensite and compressive residual stresses. This paper explores the heat treatment applied to 4340 cylindrical parts heated using a Nd: Yag 3 kW laser source. In this case, the hardness profile is correlated to process parameters such as the laser source power, the beam scanning speed and the revolution speed of the part during heating. Based on preliminary tests stipulating that each parameter is varied alone within a specific range, a systematic design of final tests is performed using Taguchi matrix. The obtained results are analyzed using ANOVA method to extract the effects, the contributions and the interaction between the factors. The results are then exploited to study the sensitivity of the case depth according the variation of the process parameters. The developed model exhibits good potential for converging towards a robust model able to predict the hardness curve and to generalize it for other dimensions of cylindrical parts.

Dose Distributions in Simulated Electron Radiotherapy with Intraoral Cones Using Treatment Planning System

Aim: This study aims to evaluate the difference between depth data from an intraoral cone and a conventional irradiation tube calculated using a treatment planning system (TPS), and that measured using an intraoral cone for electron radiotherapy. Background: A TPS is only compatible with conventional irradiation tubes. However, such systems are not suitable for determining dose distributions when a special cone is employed. Materials and Methods: Dose distributions were calculated using the beam data for mounted intraoral cones using a TPS. Then, the dose distribution by field size was calculated for a low-melting-point lead alloy using the beam data for a mounted conventional tube. The calculated data were evaluated against the measured intraoral-cone depth data based on the dose and depth differences. Results: The calculated data for the intraoral cone case did not match the measured data. However, the depth data obtained considering the field size determined for the lead alloy using the conventional tube were close to the measured values for the intraoral cone case. The difference in the depth at which the absorbed dose was 50% of the maximum value of the percentage depth dose was less than ±4 mm for the generalized Gaussian pencil beam convolution algorithm and less than ±1 mm for the electron Monte Carlo algorithm. Conclusion: It was found that the measured and calculated dose distributions were in agreement, especially when then electron Monte Carlo algorithm was used. Thus, the TPS can be employed to determine dose distributions for intraoral cone applications.

宽厚板轧机用Cr3钢支承辊淬硬层深度的理论预测与实验验证

差温热处理是决定支承辊工作层组织、应力分布和使用性能的关键工序。为精准控制宽厚板轧机用Cr3钢支承辊辊身淬硬层深度以进一步提高其寿命周期内的服役性能,利用ABAQUS有限元模拟软件计算了支承辊在差温热处理过程中的温度场分布,分析了距离辊身不同深度处的温度与显微组织演变,预测了差温处理过程中辊身淬硬层的深度。结果表明:当加热温度达到840℃及以上时,Cr3钢可获得耐磨性较佳的非珠光体组织;Cr3钢支承辊实验件的淬硬层深度达110 mm,表面硬度达到55 HSD以上,且距离表面110 mm深处的硬度降低不大于4 HSD;淬硬层深度的理论预测结果与实测结果吻合较好,可以实现支承辊淬硬层深度的精确控制,指导Cr3钢支承辊差温热处理工艺制定。

黄土场地挤密地基处理深度的探讨

通过分析湿陷性黄土场地上挤密地基的浸水试验结果,探讨了沉管挤密桩地基处理的深度问题,建议在处理大厚度湿陷性黄土场地上的电力工程建设项目时,可以采用沉管挤密桩处理地基,处理深度可设定为12m,这一深度不仅能有效挤密桩间土,消除地基湿陷性,降低地基渗透系数,还能使处理深度范围内的土层形成良好的承载层和隔水层,从而保证地基的稳定性和工程的安全性。

基于多机器学习的强夯有效加固深度预测对比研究

采用当前应用较为广泛的6种算法模型,即BP神经网络模型、SVM模型、RF模型、MLP模型、XGBoost模型以及朴素贝叶斯模型,对不同土质、不同夯击能量、不同夯锤面积下的强夯有效加固深度进行预测,采用均方根误差、平均绝对百分比误差、决定系数以及平均绝对误差4项指标对比各模型的预测准确率、误差及泛化能力,并结合工程实例数据做检验。结果表明,机器学习方法具有较高的预测精度和泛化能力,可通过少量且简单的强夯数据进行预测强夯有效的加固深度,能为强夯工程设计提供参考依据;在小样本的情况下,RF模型性能较为优异,其次为XGBoost模型与朴素贝叶斯模型,BP神经网络模型、MLP模型与SVM模型表现较差,建议在样本数据有限的情况下,优先选用RF模型进行强夯有效加固深度预测。

焉耆盆地农田排盐暗管布设参数研究

【目的】研究焉耆盆地典型绿洲农田排盐暗管模式下,布设参数中影响土壤排盐效果的显著因素。【方法】设置不同暗管埋深(1.2、1.5 m)与间距(20、30、40 m),开展排盐试验,结合极差和方差分析方法,研究淋洗前后土壤剖面的水盐变化规律和暗管排水排盐量差异。【结果】①暗管排水过程中,田间持水率状态土壤经淋洗后能迅速达到饱和状态且位于暗管上方的土层能够排出土壤多余水分,土壤含水率与暗管布设参数未呈显著性关系;②在0~60 cm土壤深度内,土壤脱盐率与间距、埋深及组合有显著交互作用,暗管间距与埋深组合与单因素间距相比对脱盐率影响更显著。相同暗管间距下:暗管埋深越深,0~60 cm内的土壤脱盐率越高;相同暗管埋深下:当暗管间距为30 m时,0~60 cm内的土壤脱盐率最高,与20、40 m间距有显著差异(P<0.05);③在排水阶段初期,各处理暗管的排水和排盐量呈现快速增长后逐渐稳定趋势,暗管排水的电导率较为稳定,与土壤剖面的含盐量呈正相关关系。暗管埋深对累积排水和排盐量有显著性影响(P<0.05),间距对其无显著性影响(P>0.05),相较1.2 m深度,1.5 m埋深能有效提升排水效率,加速排出土壤盐分。【结论】在考虑最大脱盐率的情况下,建议将暗管埋深设为1.5 m,间距设为30 m,作为焉耆盆地农田暗管布设的参考。

地埋式设备水温与气温及埋深的关系研究

为了解地埋式农污处理设备水温的影响因素,对江苏苏南地区2台地埋式设备水温和气温进行了全年数据监测,分析了设备水温与气温的变化关系,得出3—8月是水温上升期,此时水温较气温低1.2~8.6℃;1—2月、9—12月是水温下降期,此时水温较气温高0.2~12.8℃;水温变化比气温变化滞后,且变化幅度小;通过拟合气温和平均设备水温的关系得到Sine拟合曲线,R2=0.97076。分析了设备水温与埋深的变化关系,得出设备埋深越深,水温变化幅度越小,水温对气温敏感程度越弱。

高速公路液化土与软土交互地基强夯法处理研究

针对某高速公路中液化土与软土交互层特殊地基进行强夯法试验研究 ,提出了拟静力法确定强夯加固深度的公式 ,与Menard公式对比分析表明本文提出的强夯有效加固深度的公式具有鲜明的土力学基础 ,理论计算结果与实际检测的结果相吻合。

合肥地区膨胀土路基处置深度问题探讨

采用统计分析气候资料和现场测试含水率的方法,对合肥地区大气影响深度进行了研究,其结果表明,按气象资料统计分析法计算的大气影响深度比实际值小。在此基础上,建议按膨胀力与零膨胀率的相关性来确定膨胀土路基处置深度。通过合肥地区18个代表性土样的膨胀力试验,给出了膨胀力与零膨胀率的相关曲线,为膨胀土路基处置深度的确定提供了可靠的依据。最后,给出了合肥地区膨胀土路基不同结构部位处置深度的建议。

油井深部堵水合理深度的实验研究

在平板物理模型上研究了油井深部堵水的合理深度。所用堵剂为短交联时间的聚合物铬冻胶。模型由环氧树脂胶结石英砂制成，沿一条对角线设置高渗条带。两端设注入、采出口（井）。按常规岩心驱油程序，模型水驱至含水98％时注入堵剂，顶替至设定位置后恢复水驱。在20×20×1（cm）的可视化模型上，注入堵剂至注采井距的1／6～5／6，恢复水驱后观测到注入深度为3／6井距时，平面波及率最大，其值略小于50％。在20×20×1．5（cm）、高渗每带渗透率5．13μm^2、基质渗透率1．85／μm^2的模型上。从采出口反向注入不同量堵剂。采收率增值随堵剂注入深度的增加（采注井距的1／10-5／10）而显著增大（1．8％-38．8％），但单位体积堵剂采收率增值在注入深度为3／10井距时最大，为5．35％／mL（孔隙体积22cm^3）。在13．5×13．5×0．15（cm）的可视化模型上，从采出口反向注入不同量堵剂，注入深度由1／10井距增加至5／10井距时观测到波及面积增大，采收率增值由2．2％升至17．7％。但注入深度为3／10井距时单位注入深度的采收率增值最大。考虑经济效益，合理深度为采注井距的3／10。指出油井深部堵水的关键。一是堵剂，另一是堵剂放置方式。图14表2参2。

饮用水微污染处理技术研究进展

概述了饮用水微污染的现状及危害;综述化学氧化,吸附及生物等饮用水微污染的预处理技术,着重介绍强化混凝,臭氧活性炭,生物活性炭,臭氧生物活性炭,光化学催化,膜法及新型生物反应器等深度处理的方法原理及应用前景,并阐明各自的优缺点。

窄带成像技术联合放大内镜JES分型对早期食管癌的诊断价值

目的探讨放大内镜日本食道学会(Japan Esophageal Society,JES)分型对早期食管癌的诊断价值。方法回顾性收集2014年1月至2020年10月于首都医科大学附属北京友谊医院行白光内镜检查高度疑似早期食管癌病灶或经活检证实为早期食管癌的203处病灶,所有病灶均行放大内镜窄带成像(narrow-band imaging magnifying endoscopy,NBI-ME)检查,并接受内镜或手术治疗,以术后病理结果作为“金标准”,分析放大内镜下JES分型对早期食管癌浸润深度的诊断价值。结果NBI-ME模式下JES分型B1型、B2型判断早期食管癌准确度分别为63.5%(95%CI:63.3%~63.8%)和71.9%(95%CI:71.7%~72.1%),灵敏度分别为65.7%(95%CI:58.0%~73.5%)和75.0%(95%CI:60.0%~90.0%),特异度分别为58.3%(95%CI 45.9%~70.8%)和71.3%(95%CI:64.6%~78.1%)。比较放大内镜JES分型及术后病理判断病变浸润深度的一致性,Kappa值为0.25,差异有统计学意义(P<0.01)。结论JES分型能够诊断早期食管癌和预测肿瘤浸润深度,但效果欠佳,预测结果与金标准一致性较低,需要更多多中心大样本对照研究进一步论证。

砂土地基强夯地面变形与加固深度的半模试验研究

在量纲分析的基础上,利用尺寸50cm×40cm×60cm(长×宽×高)的玻璃模型箱,采用3种不同干重度的砂土,对之施加4种不同能量的冲击能,观测了不同的夯击能作用时夯点下的地面变形与中心点下不同深度的竖向位移,拟合了位移—深度关系,建立了夯坑深度和有效加固深度与土质参数及施工工艺参数之间无量纲的相关方程,并用工程实例对方程进行了验证。结果表明:方程可有效地定量分析强夯时的夯坑深度和有效加固深度,对强夯法的设计与施工具有一定的指导意义。

冲击波碎石术中治疗深度与疗效的关系研究

目的:探讨输尿管结石冲击波碎石术(SWL)中的治疗深度与冲击剂量及疗效的关系。方法:输尿管结石患者932例,分为上中段输尿管组(A组)和下段输尿管组(B组),每组再按治疗深度范围分为连续性的三个亚组,比较各组治疗深度对SWL冲击剂量和疗效的影响;再以残石作为因变量,以组别、性别、年龄、病程、肾积水程度、结石大小、治疗深度、电压、冲击次数、复震为自变量拟合两分类Logistic回归模型,分析各因素对残石的影响。结果:单因素分析结果显示在A、B两组中,治疗深度与治疗电压、无石率、复震率、效率商、术后肾绞痛发生率均未发现存在统计学关联,但上中段输尿管组随着治疗深度的增加,冲击次数增加(P=0.016)。而Logistic回归分析结果显示随着治疗深度的增加,无石率有下降的趋势(P=0.049)。结论:治疗深度是SWL疗效的影响因素,提示缩短治疗深度可提高SWL效率。

新生儿泪囊炎的二次治疗时机与探通进针深度的分析

目的:探讨新生儿泪囊炎二次治疗的时机与探通进针的深度。方法:分析一次治疗失败的32眼新生儿泪囊炎患儿,采用二次鼻泪管探通后的治疗效果,并对一次探通成功的115眼患儿的探针进针深度进行统计。结果:由于泪道探通的有效率与年龄有关,本研究三组患儿的年龄构成差异无统计学意义(P>0.05)。按间隔时间分组,1wk以内的11只患眼中,经二次治疗有效10眼,占91%;1～2wk的13只患眼中,有效12眼,占92%;2wk以上8只患眼中,有效6眼,占75%。有效率差异有统计学意义,间隔1～2wk二次治疗的成功率最高,并发症发生率最低(P<0.05)。<3月龄患儿操作中进针深度24～26.5mm,3～7月龄26.5～28.5mm,7～12月龄28.5～30mm,12～36月龄30～32.5mm。结论:间隔1～2wk再行二次治疗的成功率最高,并发症发生率最低,是最佳治疗时机。操作中,<3月龄患儿操作中进针深度24～26.5mm,3～7月龄26.5～28.5mm,7～12月龄28.5～30mm,12～36月龄30～32.5mm。

大厚度湿陷性黄土场地地基基础设计分析

建筑物从低阶地向高阶地扩展是建设工程发展的必然趋势,在大厚度湿陷性黄土场地的地基基础设计中,面临着缺少经验、按常规设计思路不能满足规范要求等问题。分析认为大厚度湿陷性黄土场地应注重考虑工程场地的水环境和基底下土层的具体状况,当能确定通过一定的排水措施和防水措施可以避免黄土浸水湿陷时,可以以防水措施为主设计地基基础,选用合理的地基基础型式和地基处理深度。同时结合实际工程加以分析,阐述大厚度湿陷性黄土场地地基基础设计的思路。

双频双对电极射频热疗比吸收率及温度场模拟

针对双频双对电极射频热疗的比吸收率和瞬态温度分布进行了物理、数学建模和数值模拟计算。该模型能真实反映电磁波在生物组织中的衰减。在非稳态温度场模拟中考虑了血液灌流量随温度变化和肿瘤区低血液灌流的特点。对双频双对电极射频热疗电磁能量分布和温度分布的特点、电极位置和电极功率对有效治疗深度的影响作了细致的分析讨论。

用于慢性软组织损伤的大功率光谱治疗仪

光谱波段和治疗光强度是光治疗的关键,决定了适应症、治疗深度和疗效。基于水滤红外线A原理,本文采用大功率高效卤素灯为光源,通过对光束整形、密闭液体过滤器以及电子学控制等系统设计了大功率光谱治疗仪,其基本性能与国外先进产品基本相同。该治疗仪的光谱、光功率密度、电气安全性和电磁兼容性通过了医疗器械注册检验,并应用于慢性软织损伤炎症、疼痛的临床治疗中。临床实验结果显示,71例患者在经过(6±1)天治疗后的总有效率达100%,显效率达80.28%,未发生不良反应。该治疗仪提升了有效光谱宽度和治疗光强度,降低了热效应,提高了穿透深度和疗效,有望广泛用于软组织的损伤、慢性炎症、疼痛及伤口愈合等领域。