Renewable energy supply chains,performance, application barriers,and strategies for further development

Due to the depletion of traditional energy resources, such as crude oil, coal, and natural gas, many initiatives all over the world have addressed the efficient use or replacement of these resources. Several renewable energy sources have been introduced as alternatives to traditional sources to protect environmental resources and to improve the quality of life. This study assesses renewable energy sources from a supply chain perspective and presents an investigation of renewable energies focusing on four main components: renewable energy supply chain, renewable energy performance, and barriers and strategies to its development. The study provides managerial insights to governments, researchers, and stakeholders for the initiation of renewable energy use, and suggestions for overcoming the barriers to its development.     

Automated detection of fovea in fundus images based on vessel-free zone and adaptive Gaussian template

This study developed a computerised method for fovea centre detection in fundus images. In the method, the centre of the optic disc was localised first by the template matching method, the disc–fovea axis (a line connecting the optic disc centre and the fovea) was then determined by searching the vessel-free region, and finally the fovea centre was detected by matching the fovea template around the centre of the axis. Adaptive Gaussian templates were used to localise the centres of the optic disc and fovea for the images with different resolutions. The proposed method was evaluated using three publicly available databases (DIARETDB0, DIARETDB1 and MESSIDOR), which consisted of a total of 1419 fundus images with different resolutions. The proposed method obtained the fovea detection accuracies of 93.1%, 92.1% and 97.8% for the DIARETDB0, DIARETDB1 and MESSIDOR databases, respectively. The overall accuracy of the proposed method was 97.0% in this study.     

Nanoscratch Characterization of GaN Epilayers on c- and a-Axis Sapphire Substrates

In this study, we used metal organic chemical vapor deposition to form gallium nitride (GaN) epilayers on c- and a-axis sapphire substrates and then used the nanoscratch technique and atomic force microscopy (AFM) to determine the nanotribological behavior and deformation characteristics of the GaN epilayers, respectively. The AFM morphological studies revealed that pile-up phenomena occurred on both sides of the scratches formed on the GaN epilayers. It is suggested that cracking dominates in the case of GaN epilayers while ploughing during the process of scratching; the appearances of the scratched surfaces were significantly different for the GaN epilayers on the c- and a-axis sapphire substrates. In addition, compared to the c-axis substrate, we obtained higher values of the coefficient of friction (μ) and deeper penetration of the scratches on the GaN a-axis sapphire sample when we set the ramped force at 4,000 μN. This discrepancy suggests that GaN epilayers grown on c-axis sapphire have higher shear resistances than those formed on a-axis sapphire. The occurrence of pile-up events indicates that the generation and motion of individual dislocation, which we measured under the sites of critical brittle transitions of the scratch track, resulted in ductile and/or brittle properties as a result of the deformed and strain-hardened lattice structure.     

Controlling the morphology of poly(3‐hexylthiophene)/methanofullerene film through a dynamic‐cooling and freeze‐drying process

A dynamic‐cooling and freeze‐drying (DCFD) process has been applied to the fabrication of polymer solar cells. The dynamic‐cooling process allows poly(3‐hexylthiophene) molecules to aggregate in solution into a more organized structure during the cooling process; the freeze‐drying process prevents severe agglomeration of [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) during the solvent removing process. Application of these two processes to the preparation of the poly(3‐hexylthiophene)/methanofullerene photoactive layer results in an enhanced poly(3‐hexylthiophene) aggregation and smaller PCBM agglomerates. Devices fabricated using the DCFD process generate 14% more in current density than those prepared by the spin‐coating process under AM1.5G illumination. © 2015 Society of Chemical Industry     

Preparation of PZN-Based Ceramics Using a Sequential Mixing Columbite Method

In this experiment Pb(Zn_1/3Nb_2/3)O₃(PZN)-BaTiO₃ (BT)-Pb(Zr_0.52Ti_0.48)O₃ (PZT) ceramics were prepared using solid state reactions via columbite method by mixing the relevant oxides and were processed employing conventional sintering techniques. Dielectric, ferroelectric and piezoelectric properties were evaluated and the corresponding microstructures were examined using transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The experimental results imply that it is difficult to prepare PZN-PZT-BT ceramics with a full perovskite structure using a conventional columbite method, i.e., PZN was prepared using the columbite method and then mixed, calcined and sintered with PT, PZ and BT. A modified approach (MC) of mixing and calcining all B-site elements first, then mixing and sintering with all A site elements was adopted. Electrical properties were enhanced but a small amount of pyrochlore phase still exists. Finally, a mixing and calcining sequence (sequential mixing columbite, SMC) of well calcined B-site elements, firstly with BaO then with PbO was utilized. A full perovskite structure of the specimen with excellent electrical properties can be obtained. Microstructural investigations showed Ba segregation at triple junctions for IC and MC processes, implying that stabilization of the perovskite structure of the specimens was not completely achieved due to element segregation.     

Synthesis and characterization of the iron/copper composite as an electrode material for the rechargeable alkaline battery

Iron/copper composite particles were synthesized by a chemical reduction method and then used as the anode material for a rechargeable alkaline battery. The particle size and structure of the samples were characterized by SEM and XRD. Their electrochemical performance was also studied. The results showed that the iron/copper composite prepared by this method is nanosized. Copper improves the electron transfer between particles, and the nanosized iron/copper composite not only has a high electrochemical capacity of up to 800 mAh g⁻¹(Fe to Fe(III)), but also has an excellent rate-capacity performance at a current density of 3200 mA g⁻¹. Compared with the iron nanoparticle without copper, the iron/copper composite sample maintains a smaller particle size during electrochemical cycling, and therefore improves the cycling stability of the iron electrode.     

超快速加热退火下保温时间对5083铝合金组织及力学性能的影响

利用Gleeble-3500热模拟系统和电子背散射衍射(EBSD)技术对5083铝合金超快速退火组织的演变规律进行了研究,探讨了5083铝合金经过80%冷轧变形后以500 ℃/s加热至450 ℃时,不同保温时间(1~60 s,冷却速度40 ℃/s)对退火组织及力学性能的影响。结果表明,随退火保温时间从1 s延长到60 s,5083铝合金的平均晶粒尺寸由4.94 μm增大到6.44 μm,合金中主要产生了再结晶立方退火织构{001}<100>、旋转立方织构{001}<110>,以及少量的高斯织构{011}<100>和黄铜型织构{011}<211>。当退火保温时间从1 s增加到60 s,整体上合金中的再结晶退火织构先增强再减弱。退火保温时间对5083铝合金的强度影响较小,5083铝合金的屈服强度、抗拉强度没有明显的变化,分别约为170 MPa、326 MPa,而其伸长率由25.63%逐渐增大至30.06%,最后又降低至25.20%。     

MEMS压电-磁电复合式振动能量采集器

具有高能量输出密度的自我供电振动能量采集技术有着迫切的应用需求,是智能化MEMS器件系统发展的重要方向。研究了一种可将外界环境振动能转化为电能的MEMS压电-磁电复合振动能量采集器,其综合了压电发电和磁电发电的优势,为新型MEMS供电研究提供了新思路。利用溶胶-凝胶工艺完成锆钛酸铅(PZT)压电功能薄膜的制备,采用MEMS加工技术完成器件四悬臂梁-中心质量块基础结构的设计和制作,结合集成封装技术实现微结构与永磁铁的微组装。测试结果表明:在一阶谐振频率247 Hz,10 g加速度激励的振动状态下,器件压电部分压电敏感单元与磁电部分电感线圈的单位体积最大有效输出电压分别为2.066×107和5.002×106 mV/cm3。     

Negotiation‐based decision support model for utility relocations in transportation infrastructure projects

Highway projects in metropolitan areas often require that adjacent utilities be relocated to accommodate new or expanded highway facilities. Traditionally, utility owners have been responsible for their own relocations prior to highway construction. However, utility relocation delay was reported as one of the root causes of overall project delays in highway construction. In the USA, one strategic approach sporadically taken over the past 15 years by some state departments of transportation (DOTs) has been to combine utility relocation work with the highway contractor's scope of work. While the combined strategy offers many benefits, it does have its own set of challenges and disadvantages. Many of these difficulties involve disagreements between DOTs and utility owners over the appropriateness of the combined strategy for particular types of relocations. Hence, a negotiation‐based decision support model (DSM) for determining whether to use the combined strategy was developed to provide guidance to both DOTs and utility decision makers during the planning and design phases of highways. A literature review and interviews with experts from both DOTs and the utility industry were conducted to identify significant factors as well as their impact levels on the decision. A DSM aiming at synthesizing the factors and orchestrating the negotiation process for the decision was proposed and verified. As suggested by the model evaluators, the proposed DSM can improve the quality of this complex decision‐making process, especially for less experienced project managers or designers.