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A dual-band metasurface antenna is designed consisting of three-layer metal patches and two-layer dielectric substrates. To facilitate the modal analysis of the metasurface, Characteristic Mode Analysis (CMA) is used to analyze the metasurface antenna with 4 × 4 rectangular patches, and the performance of the antenna is optimized based on the Modal Significance (MS) curves. In order to excite the current of different characteristic modes at certain frequencies, symmetric resonant arms and cross-shaped impedance matching converters are used in the feeding structure. The measured results are consistent with the simulated values, and the designed antenna can yield gains of 7.67 dBi at 3.5 GHz and 7.28 dBi at 4.9 GHz, which provides the potential applications in 5G and other wireless communications. [ABSTRACT FROM AUTHOR]

LiFePO4 (LFP) is a promising cathode material for lithium-ion batteries. In this study, low temperature direct writing (LTDW)-based 3D printing was used to fabricate three-dimensional (3D) LFP electrodes for the first time. LFP inks were deposited into a low temperature chamber and solidified to maintain the shape and mechanical integrity of the printed features. The printed LFP electrodes were then freeze-dried to remove the solvents so that highly-porous architectures in the electrodes were obtained. LFP inks capable of freezing at low temperature was developed by adding 1,4 dioxane as a freezing agent. The rheological behavior of the prepared LFP inks was measured and appropriate compositions and ratios were selected. A LTDW machine was developed to print the electrodes. The printing parameters were optimized and the printing accuracy was characterized. Results showed that LTDW can effectively maintain the shape and mechanical integrity during the printing process. The microstructure, pore size and distribution of the printed LFP electrodes was characterized. In comparison with conventional room temperature direct ink writing process, improved pore volume and porosity can be obtained using the LTDW process. The electrochemical performance of LTDW-fabricated LFP electrodes and conventional roller-coated electrodes were conducted and compared. Results showed that the porous structure that existed in the printed electrodes can greatly improve the rate performance of LFP electrodes. [ABSTRACT FROM AUTHOR]

The current codes and specifications use the equivalent beam-column method to predict the in-plane stability capacity of concretefilled steel tubular (CFST) arches. Using this method, the effects of the rise-span ratio and the nonuniform moment on the stability capacity of CFST parabolic arches are not considered. This may induce a difference between calculation results and actual structural stability capacity. To study the effects of the rise-span ratio and the nonuniform moment, six fixed CFST parabolic arches, with rise-span ratios of 1/4.5, 1/6, and 1/9, were tested and analyzed in this study. The failure patterns and mechanisms were studied. The confining effect of the steel tube to the concrete at failure was investigated. The influence of the rise-span ratio and loading conditions on the in-plane stability of fixed CFST arches was also considered. A nonlinear elastic-plastic finite-element (FE) model was used to predict the buckling behavior of the fixed CFST parabolic arches. Based on the test and the FE results, a design equation is proposed for the design of in-plane stability of fixed CFST parabolic arches under combined bending and compression. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tubular (CFST) arch bridges have the advantages of high compressive strength, light self-weight, and convenience in construction, and thus have been widely used in recent years. The current codes or specifications use the equivalent beam-column method to predict the in-plane strength of CFST arches. In this method, the CFST arches are considered under central or eccentric axial compression and are treated similarly to CFST columns. However, different from the CFST columns, the in-plane strength of CFST arches is affected by not only the slenderness ratio but also the rise-span ratio. Especially for the arches with small rise-span ratios, the prebuckling deformation becomes quite nonlinear, leading to a remarkable decrease in in-plane strength. Therefore, it is doubtful if the current method for in-plane strength design of CFST arches can provide correct predictions. In this paper, the elastic buckling and elastic-plastic buckling behaviors of fixed CFST parabolic arches that are subjected to uniform axial compression are investigated. The effect of the rise-span ratio on both the elastic buckling load and the in-plane strength are studied. A new method for the prediction of the in-plane strength of fixed CFST parabolic arches that are subjected to uniform axial compression is developed by considering both the slenderness ratio and the rise-span ratio. [ABSTRACT FROM AUTHOR]

Web 2.0 enables a two-way interaction between servers and clients. GPS receivers become available to more citizens and are commonly found in vehicles and smart phones, enabling individuals to record and share their trajectory data on the Internet and edit them online. OpenStreetMap (OSM) makes it possible for citizens to contribute to the acquisition of geographic information. This paper studies the use of OSM data to find newly mapped or built roads that do not exist in a reference road map and create its updated version. For this purpose, we propose a progressive buffering method for determining an optimal buffer radius to detect the new roads in the OSM data. In the next step, the detected new roads are merged into the reference road maps geometrically, topologically, and semantically. Experiments with OSM data and reference road maps over 2 an area of 8494 km² in the city of Wuhan, China and five of its 5 km x 5 km areas are conducted to demonstrate the feasibility and effectiveness of the method. It is shown that the OSM data can add 11.96% or a total of 2008.6 km of new roads to the reference road maps with an average precision of 96.49% and an average recall of 97.63%. [ABSTRACT FROM AUTHOR]

BiHoTiO and (BiHo)TiVO (BHTV) ( x = 0.3, 1.2, 3.0 and 6.0%) thin films were prepared on Pt/Ti/SiO/Si substrates by sol-gel method. The effect of V content on their microstructure and ferroelectric properties were investigated. All the BHTV samples consisted of the single phase of Bi-layered Aurivillius phase. The B-site substitution with high-valent cation of V, in BiHoTiO films, enhanced the remanent polarizations (2P) and reduced the coercive field (2E). The BHTV film with x = 0.3% exhibited the better electrical properties with 2P 45.5 μC/cm, 2E 257 kV/cm, good insulting behavior, as well as the fatigue-free characteristic. [ABSTRACT FROM AUTHOR]