Solution combustion synthesis of cerium oxide nanoparticles as corrosion inhibitor

In this study, combustion synthesis of cerium oxide nanoparticles was reported using cerium nitrate hexahydrate as starting material as well as urea, glycine, glucose, and citric acid as fuels. The influence of fuel type on structure, microstructure, band gap, and corrosion inhibition was investigated. X-ray diffraction (XRD) patterns and scanning electron microscopy micrographs showed that CeO₂ nanoparticles with different morphologies were obtained depending on the fuel type. Microstructural changes from unreacted gel to sponge-like morphologies were resulted by varying the fuel type from urea, glycine, and glucose to citric acid. In addition to Ce–O bonds, Fourier transform infrared analysis showed carbon bonds of carbonaceous compositions from incomplete combustion which were declined during combustion reaction. Furthermore, corrosion analyses showed that samples synthesized using urea fuel released the most Ce⁺⁴ ions and could have better protection than other samples.     

聚乙烯醇/牛I型胶原支架材料的制备及评价

研究了一种聚乙烯醇(PVA)和胶原(COL)复合支架材料的制备方法。采用氨基硅烷对PVA海绵表面进行了氨基化修饰后，通过戊二醛溶液交联牛Ⅰ型胶原(COL)，最后通过赖氨酸溶液封闭，获得一种PVA/COL复合支架材料。采用扫描电镜(SEM)、X光电子能谱仪(XPS)、傅里叶红外光谱(FT-IR)等手段对支架材料的理化性能进行表征，并通过细胞实验对支架材料的生物学性能进行评价。结果表明，经过COL修饰的PVA孔隙率为21.33%，平均孔径为168.68 ?m且均匀分布，支架材料接触角为20.03°。对支架材料的生物学评价结果表明C3A细胞在复合材料上黏附良好，优于PVA组；CCK-8增殖检测结果表明细胞在复合材料上呈增殖生长趋势，与对照组PVA相比差异显著(P?0.01)。将PVA和COL复合制备得到的支架材料具有良好的理化及生物学特性，具有广阔的应用前景。     

槽式太阳能集热管内相变微胶囊悬浮液的热力性能分析

针对传统使用水基和油基的太阳能集热器换热效果低和管壁热应力大的问题，以相变微胶囊悬浮液为工作流体，对抛物型槽式太阳能集热器进行了三维建模。采用蒙特卡罗射线追踪法结合有限容积法和有限元法的方法求解了太阳能集热管的光?热?力耦合问题，采用欧拉?欧拉多相流模型研究了相变微胶囊悬浮液在集热管内的流动换热特性。结果表明，相变微胶囊悬浮液强化了集热管内的对流换热，不仅降低了集热管的沿程壁温，且减少了集热管的周向温差，均化了集热管温度分布。集热管周向等效热应力呈花瓣型分布，对应的5个高温度梯度的位置附近(圆周角θ=5°, 90°, 175°, 225°和315°)出现等效应力局部峰值。吸热管内壁面θ=90°处轴向热应力为压应力，作用于整个管程，而径向热应力和切向热应力为拉应力，主要作用在进出口端。相变微胶囊悬浮液浓度越高，强化换热效果越好，集热管热应力越小，但产生的压降也随之增大。     

水泵水轮机导叶动态水力矩特性分析

采用SST k-ω湍流模型对某高水头水泵水轮机进行全流道三维非定常数值模拟,分别对在水轮机工况和水泵工况运行下的导叶动态力矩特性进行分析。结果表明:在水轮机工况下,随着流量的增大,不同位置处导叶的动态水力矩变化规律一致,力矩值由正值变为负值,力矩脉动频率与转轮叶片数相关,流量越大,叶频影响越显著;在水泵工况下,最高扬程工况时导叶水力矩脉动频率主频为转频且脉动幅值较大,而最低扬程工况下导叶水力矩脉动主频为叶频,力矩脉动幅值较小。     

Control Model for Large‐Sized Gantry Type Linear Motor Slider

At present, many industrial carrier devices utilize linear motor sliders. However, a heavier load requires a linear motor (which is an example of a direct drive device) to get higher power, compared with a rotary motor with a ball screw slider (which is an example of an indirect drive device). In order to obtain higher power at a lower cost, a linear slider with multiple motors can be utilized, for example, a gantry type linear motor slider. Moving the gantry type slider requires two linear motors that are set up in parallel to enable synchronization control. Some conventional synchronization control methods have been proposed for the parallel twin linear slider; however, a large‐scaled gantry type linear motor slider has two unique problems: mechanical distortion caused by the limitations of installation environment and coupling caused by joints with low stiffness. This paper proposes a control model to solve these problems, and an identification method of each parameter. Furthermore, the effectiveness of the control model is verified by comparison with simulation results and experimental results.     

The impact of the ICT4D project on sustainable rural development using a capability approach: Evidence from Bangladesh

Information and Communication Technology for Development (ICT4D) projects have shown a great promises in recent years. However, simply materializing of ICT4D projects is not enough for minimizing the prevalent digital divide in rural areas in developing countries. For the success of an Information and Communication Technology (ICT) intervention, it is important to consider the capabilities of users, who are responsible for converting ICT resources into outcome. While most of the ICT-related studies are focused on the adoption of actual technologies and influences of different internal and external factors on intervention outcomes, very few studies are focused on evaluating intervention outcomes and redesigning intervention strategies. In this study, I opted for using a conceptual framework following the Capability Approach that simultaneously identifies the influence factors for intervention outcome as well as evaluates the outcome based on Noble Laureate Amartya Sen’s five freedoms concept. A qualitative technique has been chosen to conduct the study. As part of the impact evaluation of an ICT4D intervention, a project known as Union Digital Centres (UDCs) in Bangladesh was selected. A total of ten themes are identified indicating that the outcome of the intervention is contributing to socio-economic and human development. However, the study has revealed that lack of capabilities of users (e.g. prior knowledge and financial inability) bar the UDC programs to fulfill their goals at highest level. This study would practically help the UDC policy makers to adjust the UDC intervention design by addressing the shortcomings of the users to yield higher UDC program outcome. Additionally, this study theoretically contributes in ICT adoption literature by showing that there is a mutual influence between users’ capabilities and ICT-related project outcomes. Finally, using specific case study (ICT4D project in Bangladesh), this study contextualizes Amartya Sen’s five freedoms concept in the ICT-specific context.     

裴沟煤矿典型断裂构造带水化学变化特征

断裂运动是错综复杂的地质作用，物质组成的变化能够通过水质中阴阳离子含量直观表现。以裴沟煤矿近20年来的突（涌）水点化验数据为依据探究各含水层水化学普遍性质，发现阳离子含量和矿化度可以作为水源判别的重要指标，以典型构造浮山寨断层为对象研究断裂构造带水化学变化特征，结果显示距离断裂构造带越近，水中Ca²⁺+Mg²⁺含量减小、Na⁺+K⁺含量增大、矿化度降低，揭示断层两盘不同含水层间水掺和程度。     

Developing microencapsulated 12‐hydroxystearic acid (HSA) for phase change material use

Phase change materials (PCM) have an increasingly more important role as a thermal energy storage (TES) media. However, leakage problem of PCM causes limitation during their integration in TES systems. Therefore, the encapsulation of PCMs is attracting research interest to extend usage of PCMs in real TES applications in recent years. In this study, hydroxystearic acid (HSA) was encapsulated with polymethyl methacrylate (PMMA) and different PMMA comonomer shells via emulsion polymerization method for the first time in literature. HSA with high melting temperature range (74–78°C) can widen the scope of using PCMs, and the encapsulated form can make it more versatile. The chemical structures, morphologies, and thermophysical properties of capsules were determined by FT‐IR, SEM, DSC, TGA, and thermal infrared camera. Among the produced HSA capsule candidates, PMMA‐HEMA is the most promising with latent heat of 48.5 J/g with melting range of 47 to 85°C. SEM analysis indicated that the capsules have spherical shape with compact surface at nano‐micro (100–440 nm) size range; however, some capsules exhibited agglomeration.     

Extensive evaluation and classification of low-cost dust sensors in laboratory using a newly developed test method

An extensive evaluation of low-cost dust sensors was performed using an exponentially decaying particle concentration. A total of 264 sensors including 27 sensors with light-emitting diodes (LEDs) and 237 sensors with laser lighting sources were tested. Those tested sensors were classified into 4 groups based on the deviation from the reference data obtained by a reference instrument. The response linearities of all the tested samples for PM₁, PM_2.5, and PM₁₀ were in excellent agreement with the reference instrument, except a few samples. For the measurements of PM₁ and PM_2.5, the lighting source, that is, LED or laser, did not show any significant difference in overall sensor performance. However, LED-based sensors did not perform well for PM₁₀ measurements. The 32, 24, and 16% of all the tested sensors for PM₁, PM_2.5, and PM₁₀ measurement, respectively, are in the category of Class 1 (reference instrument reading ± 20%) requirement. The performance of the low-cost dust sensors for PM₁₀ measurement was relatively less satisfactory.