ZL109铝合金车削表面完整性实验研究

设计了三因素四水平正交车削实验,综合运用极差分析、方差分析等方法,研究了切削参数对硅铝合金ZL109车削表面完整性的影响规律,得到了切削参数对于表面粗糙度、残余应力和显微硬度的影响程度和趋势,分析了ZL109车削表面完整性的形成机理,以期为切削参数优选提供实验和理论基础。研究结果表明,进给量f对表面粗糙度具有显著影响,切削速度v和进给量f增加会导致表面残余拉应力增大,显微硬度受切削参数的影响较小。     

Critical state model for structured soil

Structure is an evident determinant for macroscopic behaviors of soils. However, this is not taken into account in most constitutive models, as structure is a rather complex issue in models. For this, it is important to develop and implement simple models that can reflect this important aspect of soil behavior. This paper tried to model structured soils based on well-established concepts, such as critical state and sub-loading. Critical state is the core of the classic Cam Clay model. The sub-loading concept implies adoption of an inner (sub-loading) yield surface, according to specific hardening rules for some internal strain-like state variables. Nakai and co-workers proposed such internal variables for controlling density (ρ) and structure (ω), using a modified stress space, called t_ij. Herein, similar variables are used in the context of the better-known invariants (p and q) of the Cam Clay model. This change requires explicit adoption of a non-associated flow rule for the sub-loading surface. This is accomplished by modifying the dilatancy ratio of the Cam Clay model, as a function of the new internal variables. These modifications are described and implemented under three-dimensional (3D) conditions. The model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured soils. The good agreements show the capacity and potential of the proposed model.     

Artificial neural networks as alternative tool for minimizing error predictions in manufacturing ultradeformable nanoliposome formulations

This work was aimed at determining the feasibility of artificial neural networks (ANN) by implementing backpropagation algorithms with default settings to generate better predictive models than multiple linear regression (MLR) analysis. The study was hypothesized on timolol-loaded liposomes. As tutorial data for ANN, causal factors were used, which were fed into the computer program. The number of training cycles has been identified in order to optimize the performance of the ANN. The optimization was performed by minimizing the error between the predicted and real response values in the training step. The results showed that training was stopped at 10?000 training cycles with 80% of the pattern values, because at this point the ANN generalizes better. Minimum validation error was achieved at 12 hidden neurons in a single layer. MLR has great prediction ability, with errors between predicted and real values lower than 1% in some of the parameters evaluated. Thus, the performance of this model was compared to that of the MLR using a factorial design. Optimal formulations were identified by minimizing the distance among measured and theoretical parameters, by estimating the prediction errors. Results indicate that the ANN shows much better predictive ability than the MLR model. These findings demonstrate the increased efficiency of the combination of ANN and design of experiments, compared to the conventional MLR modeling techniques.     

Airborne spread of expiratory droplet nuclei between the occupants of indoor environments: A review

This article reviews past studies of airborne transmission between occupants in indoor environments, focusing on the spread of expiratory droplet nuclei from mouth/nose to mouth/nose for non‐specific diseases. Special attention is paid to summarizing what is known about the influential factors, the inappropriate simplifications of the thermofluid boundary conditions of thermal manikins, the challenges facing the available experimental techniques, and the limitations of available evaluation methods. Secondary issues are highlighted, and some new ways to improve our understanding of airborne transmission indoors are provided. The characteristics of airborne spread of expiratory droplet nuclei between occupants, which are influenced correlatively by both environmental and personal factors, were widely revealed under steady‐state conditions. Owing to the different boundary conditions used, some inconsistent findings on specific influential factors have been published. The available instrumentation was too slow to provide accurate concentration profiles for time‐dependent evaluations of events with obvious time characteristics, while computational fluid dynamics (CFD) studies were mainly performed in the framework of inherently steady Reynolds‐averaged Navier‐Stokes modeling. Future research needs in 3 areas are identified: the importance of the direction of indoor airflow patterns, the dynamics of airborne transmission, and the application of CFD simulations.     

磁絮凝强化技术处理厌氧消化污泥脱水液

为满足后续生物处理单元对固体悬浮物（SS）和铁浓度的进水要求，采用磁絮凝强化技术对厌氧消化污泥脱水液进行预处理。通过正交试验和单因素试验，本文考察了混凝水力条件、聚合氯化铝（PAC）投加量、聚丙烯酰胺（PAM）投加量、磁粉投加量及药剂投加顺序对磁絮凝效果的影响。试验结果表明：磁絮凝强化技术在快搅300r/min（2min）、慢搅100r/min（15min）、静置10min时，依次投加磁粉（40mg/L）、PAC（30mg/L）、PAM（4mg/L）时处理效果最好。在此运行条件下，SS和Fe³⁺去除率分别为97.61%、98.24%、絮凝指数（FI值）取得最大值、zeta电位绝对值最小，絮凝效果最佳。与对照相比，磁絮凝强化技术对SS和Fe³⁺去除率分别可提高3.70%和10.82%，同时絮体最大沉降速度可提高33%。磁絮凝技术处理后的出水不仅可以满足后续生物处理单元对SS和铁浓度的要求，还可以有效提高磁絮凝体的沉降速度，减小沉淀时间，具有较好的实用价值。     

于都黄麟-祁禄山地区土地质量地球化学评价

通过对于都县黄麟-祁禄山地区开展1:5万土地质量地球化学调查,在野外土壤样品采集和化验测试的基础上,系统地研究了影响土地质量的各项地球化学指标特征与控制因素,基本查明有益元素、重金属元素分布,划分出重点污染区和绿色土地发展区,并进行土地质量等级评价,为永久基本农田建设、土地资源开发与利用等方面提出建议。     

柱淋滤模式下生活垃圾焚烧炉渣中Cu2+和Zn2+浸出规律

垃圾焚烧炉渣是一种活性材料，在其储存、预处理及应用等过程与雨水频繁接触时，炉渣中重金属随着水域环境发生迁移和浸出现象。本研究采用连续柱淋滤试验装置模拟自然降雨，开展了0～5mm和5～10mm焚烧炉渣的动态淋滤毒性浸出分析，重点研究了pH和降雨强度对Cu²⁺和Zn²⁺的浸出影响。结果表明，动态淋滤过程中，淋滤液pH变化对Cu²⁺和Zn²⁺的浸出水平影响显著，且在酸性较强淋滤液作用下Cu²⁺浸出水平比Zn²⁺更强，与Ⅴ类地表水环境浓度限值对比，在整个淋滤时间内Cu²⁺浸出浓度严重超标，在炉渣工程应用时需预防相关的环境风险；原生炉渣粒径大小与重金属浸出水平无直接相关性，但是0～5mm细炉渣中可浸出Zn²⁺含量更高，这与细颗粒物中Zn赋存形态和可溶出态含量较高有关；淋滤强度对重金属浸出水平影响主要反应了动态淋滤过程液固比和水分运移速率情况，当较低淋滤强度时具有低液固比，溶出液中重金属含量较高。     

于都县黄麟地区绿色富硒土壤分布选区评价

通过于都县黄麟地区1:5万土地质量地球化学调查,基本査明该地区农作物中硒元素及其他元素的地球化学特征,综合分析岀绿色富硒土壤分布,并优选出绿色富硒地块,为特色农产品基地建设的开发与利用提供理论依据。     

铝合金表面GPTMS硅烷膜的制备及耐蚀性能研究

为提高铝合金耐腐蚀力，运用正交试验法研究在铝合金表面制备 γ-（2，3-环氧丙氧）丙基三甲氧基硅烷（GPTMS）自组装膜最佳工艺条件，利用极化曲线和扫描电子显微镜研究该硅烷膜在铝合金表面的耐腐蚀性能。研究表明：最佳工艺条件为 100 mL溶液中， pH＝4. 5，V（GPTMS）∶V（EtOH）∶V（H₂O）= 2∶7∶91，T_{1（水解温度）}＝25 ℃，t_{1（水解时间）}＝7 h，t_{2（浸涂时间）}＝10 min，t_{3（固化时间）}＝90 min，T_{2（固化温度）}＝120 ℃，该工艺条件下制备的硅烷膜具有优异的耐腐蚀性能。