An overview of selective laser sintering and melting research using bibliometric indicators

The aim of this paper is to present an overview of published research in selective laser sintering/melting (SLS/M), by using bibliometric indicators. Bibliometrics is the quantitative statistical analysis of written publications, such as articles or books. It is useful for displaying and classifying information according to selected variables, such as authors, journals, citations, countries, and institutions. This type of review provides a clear picture of research in a targeted area, such as the most cited research, author with most publications, journal with most published papers, and universities and countries producing the largest amount of research in the target area. The Web of Science database was used to collect data on the topic of interest. The results reveal that the Rapid Prototyping journal is the most productive journal in this field, where the Huazhong University Science Technology is the most effective institution. Also China is the most productive country, whereas USA is the most influential country.     

Structure and electrochemical behavior of lithium vanadate materials for lithium batteries

New vanadate compounds having the molecular structure Li_xMg_1−xV_2−xMo_xO₆ (0 ≤ x ≤ 1) were studied. Six samples were prepared by sol-gel process from precursor using the following ratios of x = 0, 0.2, 0.4, 0.6, 0.8 and 1, respectively. These samples were labeled S1, S2, S3, S4, S5 and S6. The final process of firing occurred at 750 °C for 18 h in air. The prepared materials were characterized by XRD, SEM, IR, electron spin resonance (ESR) and magnetic measurements. The morphologies of S1, S2, S5 and S6 are prismatic as they have monoclinic crystal structures. S3 and S4 differ in the crystal morphology from the other previous samples due to their triclinic crystal lattice structure. IR spectra revealed that the bond lengths of the vanadyl groups ν_VO, ν_{sy V-O} and σ_V-O increase in the same direction from S1 to S6. The data of the ESR explain the existence of V⁴⁺ beside V⁵⁺ in S1, S4 and S6 and also presence of Mo⁵⁺ with Mo⁶⁺ in S4 and S6. S4 exhibited better magnetic susceptibility and saturated magnetization than the other samples. The first specific discharge capacities of the samples were performed. S4 showed the maximum specific capacity of 265 mAh g⁻¹ in comparison with the other samples. Cyclic voltammogram of S4 exhibited the highest current intensity in comparison with the other samples. This sample showed two peaks at 0.53 and 1.3 V versus Li/Li⁺ characterizing double de-insertions of two lithium atoms from Li_1.6Mg_0.4V_1.4Mo_0.6O_6−x and Li_0.6Mg_0.4V_1.4Mo_0.6O₆, respectively. Also, two additional peaks were characterized for the oxidation of Mo⁵⁺ to Mo⁶⁺ and V⁴⁺ to V⁵⁺ at 3.5 and 4 V, respectively.     

A study on the anchoring orientations of foam and sandwich composites with metal

Metallic anchors are used as the load transfer components for foam and sandwich composites when they are used as structural elements in design applications. The traditional method of fixation of these components is by gluing and fastening. The anchors are in the form of inserts and are imbedded in the foam during the foaming process. In this study, flexural testing was conducted on different metal anchor/foam configurations to establish typical interaction trends. The load‐deflection response, mode of failure, and fracture stresses of the structures were elucidated. Tests were conducted on foam and sandwich composites having rectangular, cylindrical, and taper geometries with different lengths. Leaf inserts were designed, manufactured, and tested inside foam and sandwich composites. Comparisons between the taper and leaf inserts are presented. Leaf inserts had better results compared with taper inserts in terms of adhesion and failure stresses. Finite element analysis (FEA) of the interactions between the inserts and the foam and sandwich composites under different loads was carried out. The FEA modeling results were very similar to the experimental results, thus validating the model. Simulations were also run with foam and sandwich composites with closeout configuration. Foam–sandwich with inserts had better adhesion and load‐bearing properties compared with same structures with closeouts. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

阴极保护—氯盐污染海工混凝土的最佳长效维修解决方案

混凝土结构劣化问题如今已成为建筑业面临的最严重的问题和巨大的挑战之一。在过去的30年里,对于遭受氯盐污染的混凝土码头结构,通常采用传统的＂打补丁＂法维修,即移除爆裂的混凝土,然后用维修砂浆回填。但是对于这些维修过的结构来说,难以得到长期的维修效果。通常在维修后短短几年内,维修过的部位周围又重新需要维修。阴极保护是一种电化学技术,利用直流电流来中止混凝土中钢筋的腐蚀进程。阴极保护方法已经被证明为氯盐污染的结构的最有效、技术上可行的长效修复解决方案。本文将重点介绍钢筋混凝土结构劣化的原因以及修复这些结构的最新方法。     

The effect of turbulence modeling on hydrogen jet dispersion inside a compartment space using the HYDRAGON code

The mitigation of hydrogen in the containment of nuclear reactor after the Loss of Coolant Accident is essential to preserve the structural reliability of the containment. This paper presents the results of the systematic work done by using the HYDRAGON code to investigate the effect of turbulence models on the concentration distribution of hydrogen and to determine the HYDRAGON code thermal-hydraulic simulation capability during a severe accident at the nuclear power plant. The HYDRAGON code is developed by the Department of Engineering Physics, Tsinghua University, which is an independent research program. The influence of various types of turbulence models, i.e. a standard k ? ? model, a re-normalized group (RNG) k ? ? model, and a realizable k ? ? model were analyzed and the simulation results were compared with the experimental data. When simulation results were compared to experimental data, it was found that, in most compartments, the standard k ? ? model generally yielded reasonable agreement with the experimental results as compared to RNG k ? ? and realizable k ? ? models; however, for probes P7 and P12, better trend was captured by RNG k ? ? and realizable k ? ? models, respectively.     

Experimental Testing of a Hybrid Power Plant for a Dirigible UAV

Dirigibles have the ability to take off and land vertically, hover and maintain lift without consuming energy, and can be easily deflated for packaging and transportation. As such, dirigibles are well suited for surveillance and surveyance missions such as rescue and aid operations after disasters. This paper reviews hybrid dirigible UAV design considerations, then presents a novel hybrid power plant design. The hybrid power plant design consists of a 2-stroke 4cc glow engine in-line with a brushless DC motor/ generator and variable pitch propeller. The experimental results have shown that the hybrid power plant is capable of producing a power output of 148.4 W.     

Optical and colorimetric studies of thorium nitrate‐doped poly(vinyl alcohol) films

In this study, poly(vinyl alcohol) (PVA) films doped with thorium nitrate hydrate [Th(NO₃)₄] have been prepared using casting technique. The optical absorption spectra were recorded at room temperature in the wavelength range 200–800 nm. From the absorption edge studies, the values of the Urbach energy (E_u) have been evaluated. These energy values vary slightly with composition, indicating that the model based on electronic transitions between localized states is not preferable. Optical parameters such as refractive index and complex dielectric constant have been determined. The dispersion of the refractive index is discussed in terms of the single‐oscillator Wemple‐DiDomenico model. Color properties of the prepared samples were discussed in the framework of CIE L*u*v* color space. POLYM. COMPOS., 35:1786–1791, 2014. © 2013 Society of Plastics Engineers     

Photocatalytic activity of Cr-doped TiO2 nanoparticles deposited on porous multicrystalline silicon films

This work deals with the deposition of Cr-doped TiO₂ thin films on porous silicon (PS) prepared from electrochemical anodization of multicrystalline (mc-Si) Si wafers. The effect of Cr doping on the properties of the TiO₂-Cr/PS/Si samples has been investigated by means of X-ray diffraction (XRD), atomic force microcopy (AFM), photoluminescence, lifetime, and laser beam-induced current (LBIC) measurements. The photocatalytic activity is carried out on TiO₂-Cr/PS/Si samples. It was found that the TiO₂-Cr/PS/mc-Si type structure degrades an organic pollutant (amido black) under ultraviolet (UV) light. A noticeable degradation of the pollutant is obtained for a Cr doping of 2 at. %. This result is discussed in light of LBIC and photoluminescence measurements.     

Analysis and interpretation of aeromagnetic data for Wadi Zeidun area,Central Eastern Desert,Egypt

The current study is mainly concerned with the analysis and interpretation of the available aeromagnetic data using different advanced processing techniques, to map the subsurface structural framework and depth estimation of these structures of the Wadi Zeidun area, Central Eastern Desert. The visual inspection of the RTP aeromagnetic map defines a rapid change in the subsurface geologic conditions in the form of the lithological characters and tectonic inferences. The shallow sources can be separated from those of deeper causatives, using power spectrum transformation tool. Two methods for locating magnetic sources, Source Parameter Image and Analytical Signal to identifying the properties of their sources indicated that, the depth calculation from the used tools ranges between 900 and 3000 m as the average ranges. Also, the comparative study among the 2D magnetic modelling was established by two profiles constructing. The mapped basement tectonic map is affected by a set of faults trending mainly in the N-S, NE-SW, NW-SE and ENE-WSW direction.