Data-driven placemaking: Public space canopy design through multi-objective optimisation considering shading,structural and social performance

In the context of ongoing densification of cities and aging urban populations, public spaces are a crucial infrastructure to support the physical and mental wellbeing of urban residents. The design of public space furniture elements is often standardised, and not considered in relation to environmental conditions and mechanisms of social interaction. This article presents a digital workflow to generate site-specific designs for shaded public seating, considering the relationships of local public places to their surroundings. A strategy for customised and site-specific design is developed through the use of multiple software tools, employing evolutionary algorithms and multi-objective optimisation. The method is applied to a small public space canopy prototype installed within a public housing estate in Hong Kong, incorporating additional criteria to achieve a low-cost and light-weight structure. Through multiple stages of refinement and optimisation, a material, structural and social performance-driven outcome was achieved that creates a shaded space for public seating, people watching and social interaction. As part of a larger research agenda exploring architectural form-finding and environmental psychology, the project represents potential new applications in the emerging field of socially driven computational design.     

Electrodeposition of the manganese-doped nickel-phosphorus catalyst with enhanced hydrogen evolution reaction activity and durability

Hydrogen technology is widely considered a novel clean energy source, and electrolysis is an effective method for hydrogen evolution. Therefore, efficient hydrogen evolution reaction (HER) catalysts are urgently needed to replace precious metal catalysts and meet ecological and environmental protection standards. Herein, Ni–Mn–P electrocatalysts are synthesized using facile electrodeposition technology. The influence of the Mn addition on the catalytic behavior is studied by the comprehensive analysis of catalytic performance and morphology of the catalysts. Among them, the Ni–Mn–P0.01 catalyst exhibits small coral-like structures, greatly improving the adsorption and desorption of hydrogen ions and reducing the overpotential hydrogen evolution. Consequently, overpotential at 10 mA cm^?2 electric current density is 113 mV, and the value of the Tafel slope achieves 74 mV/dec. Furthermore, the Ni–Mn–P catalyst shows long-time (20 h) stability at current densities of 10 and 60 mA/cm². The results confirm that the synergistic effect of Ni, Mn, and P accelerates the electrochemical reaction. Meanwhile, the addition of manganese element can change the micromorphology of the catalyst, thereby exposing more active sites to participate in the reaction, enhancing water ionization, improving the catalytic performance. This study opens a new way toward improving the activity of the catalyst by adjusting Mn concentration during the electrodeposition process.     

An effect of hydrogenation on the photoemission of amorphous SiCN films

The structure, chemical bonding and photoemission of amorphous hydrogenated silicon carbonitride (a-SiCN:H) films deposited by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyldisilazane as a main precursor at different hydrogen flow rates are studied. Film properties are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), absorption optical spectra and photoluminescence (PL). The photoluminescence spectra were presented by four photoemission bands centered at 441–451, 489–496, 530–535 and 577–601 (in nm). To explain structural and photoluminescence properties of the deposited films, first-principles molecular dynamics simulations of un-hydrogenated and hydrogenated silicon carbonitride samples were carried out. Based on experimental and theoretical results a possible explanation of the photoemission of the deposited films and its evolution with increasing hydrogen flow rate was done.     

起重机械移动综合检测平台的研制开发

起重机械作为工业发展的基础性产业，其安全使用一直备受关注，有关的检测技术和手段日新月异。文中结合起重机械检验检测工作特点和流程，基于目前日趋成熟的移动实验室技术，提出了起重机械移动综合检测平台的设计方案。对现有检测手段、业务流程、办公软件、网络系统等进行整合，将检测平台结构分为车载基础和业务测试2个功能模块，实现了起重机械一站式的业务服务、检验检测、远程联检等功能，推进检验检测工作提质增效，并具有一定的扩展性，为智慧特检提供了一种思路。     

二维编织管状织物复合材料研究进展

与传统工程金属相比,复合材料具有许多优点,近年来应用占比显著增加。编织是一种前途广阔、应用普遍的制备连续纤维增强复合材料的方法,编织结构广泛应用于医疗、航空航天、汽车等领域。文章介绍了二维编织管状复合材料的准静态力学性能,列举了二维编织管状复合材料的广泛应用,展示了二维编织管状复合材料应用的可能性和优势,最后概述和讨论了用于预测编织复合材料各项性能的大量解析模型,从而有助于编织复合材料的进一步普及。     

Exploration on the origin of enhanced piezoelectric properties in transition-metal ion doped KNN based lead-free ceramics

In this work, we studied effects of Ni₂O₃ and Co₂O₃ doping on crystal structures, microstructures, orthorhombic and tetragonal phase transition temperature (T_o-t), and electrical properties of [Li_0.06(Na_0.57K_0.43)_0.94][Ta_0.05(Sb_0.06Nb_0.94)_0.95]O₃ (LNKTSN) lead-free ceramics. The experimental results showed that the Ni₂O₃ addition with appropriate amount could shift the T_o-t downwards to the room temperature, and thus obviously increasing the room-temperature piezoelectric coefficient (d₃₃), dielectric coefficient (ε_r) and electromechanical coupling coefficient (k_p) of the LNKTSN ceramics. These were consistent with previous experimental results obtained in Fe₂O₃ doped LNKTSN ceramics. On the contrary, Co³⁺ doping shifted continuously the T_o-t upward and deteriorated obviously piezoelectric properties of LNKTSN ceramics. Fe, Co and Ni had similar ion radii and were expected to result in the same (donor or acceptor) doping effects on electrical properties of LNKTSN ceramics. The different doping effects between Co³⁺ (deterioration) and Ni³⁺ or Fe³⁺ (improvement) on the electrical properties of LNKTSN ceramics suggested that the coexistence of orthorhombic and tetragonal phases at room temperature due to downward shift of T_o-t, rather than ion doping (donor or acceptor doping) effects was the main cause for enhanced room-temperature piezoelectric properties. This conclusion can be extended to all KNN-based materials in general, thus offering principle guide for future development of new lead-free materials with good piezoelectric properties.     

Critical roles of the rhombohedral-phase inducers in morphotropic NaNbO3-BaTiO3-ABO3 quasi-ternary lead-free piezoelectric ceramics

A morphotropic phase boundary (MPB) between rhombohedral (R) and tetragonal (T) phases was identified in a few (0.9-x)NaNbO₃-0.1BaTiO₃-xABO₃ (x?=?0–0.05) lead-free systems. Critical roles of R-phase inducers were specially evaluated in terms of phase boundary position, microstructure and piezoelectric responses. The results indicate not only the tolerance factor of the ABO₃ additive but also its ferroelectricity and corresponding volume change would influence the formation of phase boundary and further determine dielectric and ferroelectric responses. The piezoelectric coefficient d₃₃ of MPB compositions was compared with theoretically-calculated d_33-cal according to d₃₃?=?2P_r·ε₃₃·Q₃₃, demonstrating that the piezoelectric response of these systems should be determined by combined effects of the phase coexistence, nano-scale domains and particularly enhanced dielectric responses. The largest d₃₃ ～305 pC/N, the highest ε₃₃^T/ε_o ～2815 and the lowest P_r ～14.7 μC/cm² were achieved in the MPB composition with 3.75% SrZrO₃. These experimental results provide a valuable reference for designing new NaNbO₃-based lead-free piezoelectric materials.     

Improved thermal shock resistance of SiCnw/PyC core-shell structure-toughened CVD-SiC coating

In-situ SiC nanowire (SiCnw)/pyrolytic carbon (PyC) core-shell structures were introduced to mainly improve the thermal shock performance of chemical vapor deposition (CVD)-SiC coating on carbon/carbon (C/C) composites. The microstructure, phase composition, and mechanical properties of the CVD-SiC coating toughened by SiCnw/PyC core-shell structures were studied as well. The results show that the introduction of SiCnw/PyC core-shell structures can effectively alleviate the mismatch of coefficient of thermal expansion (CTE) between SiC coating and C/C substrate, thus enhancing the thermal shock resistance of the coating. Furthermore, the increased numbers of interfaces in the SiC coating owing to the addition of core-shell structures are beneficial to the mechanical properties of the coating after thermal shock test.     

Reversible Flat to Rippling Phase Transition in Fe Containing Layered Battery Electrode Materials

Layered sodium transition metal oxides of NaTMO₂ (TM = 3d transition metal) show unique capability to mix different compositions of Fe to the TM layer, a phenomenon that does not exist in LiTMO₂. Here, a novel spontaneous TM layer rippling in the sodium ion battery cathode materials is reported, revealed by in situ X‐ray diffraction, Cs‐corrected scanning transmission electron microscopy, and density functional theory simulation, where the softening and distortion of FeO₆ octahedra collectively drives the flat TM planes into rippled ones with inhomogeneous interlayer distance at high voltage. In such a rippling phase, charge and discharge of Na ions take different evolution pathways, resulting in an unusual hysteresis voltage loop. Importantly, upon discharge beyond a certain Na composition, the rippling TM layer will go back to flat, giving the reversibility of such structural evolution in the following cycles.     

Enhanced piezoelectric strain of BiFeO3–Ba(Zr0.02Ti0.98)O3 lead-free ceramics near the phase boundary

The xBiFeO₃-(1-x)Ba(Zr_0.02Ti_0.98)O₃ + 1.0 mol% MnO₂ (xBF-BZT) lead-free piezoelectric ceramics were prepared by conventional solid-state reaction method. The structure, dielectric, and piezoelectric properties were studied. X-ray diffraction (XRD) analysis showed that xBF-BZT ceramics exhibited pure perovskite structure with the coexistence of tetragonal and rhombohedral phases (0.66 ≤ x ≤ 0.74). The Curie temperature T_c, the dielectric constant ε_r (1 kHz), dielectric loss tanδ (1 kHz), piezoelectric constant d₃₃, coercive field E_c (80 kV/cm), and remnant polarization P_r (80 kV/cm) of 0.7BF-0.3BZT-Mn ceramics were 491°C, 633, 0.044, 165 pC/N, 35.6 kV/cm, and 22.6 μC/cm², respectively. The unipolar strain of 0.7BF-0.3BZT reached up to 0.20% under the electric field of 60 kV/cm, which is larger than that (0.15%) of BiFeO₃–BaTiO₃ ceramics. These results indicated that the xBF-BZT ceramics were promising candidates for high-temperature piezoelectric materials.