Evaluation of a large dish‐type concentrator solar lighting system for underground car park

To utilize solar energy more efficiently and reduce lighting power consumption in underground public spaces such as car park, a large dish‐type concentrator solar lighting system is put forward along with its evaluation, which is a unique design to apply a laminated layer of beam split thin‐film coating and thin‐film solar cells onto the dish reflector. The collected sunlight is split into 2 parts, one being reflected into a fiber optical bundle and transmitted for daylighting, while the rest being absorbed by solar cells for electricity generation as the other way to replenish daylighting. A set of 4 solar lighting systems using 3.28‐m diameter dish are designed to meet the lighting requirement in a 1771‐m² underground car park. A mathematical model is adopted to calculate the output power and conversion efficiency of solar cells distributed on the parabolic dish surface. The indoor illuminance distribution is given by lighting simulation. The results indicate that the average daylight illuminance in the car park can vary between 62.7 and 284 lx on February 25, 2016 and between 62.7 and 353 lx on August 17, 2016 for 2 chosen days, respectively. For the presented design, the electricity produced by solar cells is just enough to power light‐emitting diodes for lighting meeting a criterion at night. Considering about 19% conversion efficiency of solar cells and the efficacy of 129.5 lm/W of light‐emitting diodes, the hybrid solar lighting system can have about 40% utilization ratio of solar energy, so it can be concluded that a sufficient lighting provision can be provided by the proposed large dish‐type concentrator solar lighting system for applications in underground car park.     

V2O5 nanosheets assembled on 3D carbon fiber felt as a free-standing electrode for flexible asymmetric supercapacitor with remarkable energy density

As an emerging energy storage device, supercapacitor is widely investigated owing to its excellent capability, quick charge-discharge and tremendous cycle life. The operation potential window, energy density and mass loading of supercapacitor must be taken into deep consideration for its practical application. In this work, an outstanding electrode based on CFF@V₂O₅ nanosheets was prepared. Then a free-standing asymmetric supercapacitor with CFF@V₂O₅ composite as positive electrode and CFF@AC as negative electrode was assembled. Owing to the functional groups produced on CFF after the activation, V₂O₅ nanosheets was immobilized. The composite exhibits remarkable specific capabilities of 1465 mF cm^?2 (492 F g^?1). The energy density of the assembled free-standing asymmetric supercapacitor achieves 0.928 mWh cm^?3 when the power density is 17.5 mW cm^?3. After 6000 charging-discharging cycles as under normal, bended and anti-bended conditions for respective 2000 cycles, the device retains 89.7% of the initial capacitance, exhibiting fascinating cycle stabilization. Finally, two devices linked series can lighten a LED of 1.8 V for 2 min after charging for 2.5 min, which is inspiring for the practical application and production of self-supporting asymmetric supercapacitors.     

Luminescent properties and X-ray imaging result of Lu2O3:Eu structured scintillation film on YSZ single crystal substrate by LCVD method

Micro-columnar structured europium doped lutecia (Lu₂O₃:Eu) scintillation film is one of the most attractive candidate materials for high-energy hard X-ray imaging detectors because of their excellent physical, scintillation properties and light guide effect. Lu₂O₃:Eu micro-columnar film (MCF) with 9 μm thickness was obtained on a yttrium stabilized zirconia (YSZ) (100) single crystal substrate by laser chemical vapor deposition (LCVD), and its structure, morphology, photoluminescence and scintillation properties were characterized. The structure and morphology of obtained film were investigated by grazing incidence X-ray diffraction (GIXRD) and scan electron microscopy (SEM). The photoluminescence and scintillation properties, including photoluminescence excitation (PLE), photoluminescence (PL), PL decay, X-ray excited luminescence (XEL), were measured and discussed. The X-ray imaging result of Lu₂O₃:Eu MCF on YSZ substrate was obtained for the first time and spatial resolution of 2 μm was obtained at BL13W beamline at Shanghai synchrotron radiation facility (SSRF).     

一种用于电气设备状态监测的新式FBG传感器北大核心CSCD

为了监测绕组变压器的静态应力场和发生短路等故障时的动态应力变化,设计了一种用于电气设备状态监测的新式FBG传感器。该传感器由聚醚醚酮材料封装的FBG构成,通过内部圆锥形空腔结构实现将轴向应力集中于FBG敏感位置。通过仿真对不同压力强度下传感器结构的应力场部分及形变趋势进行了计算与分析,论证了设计的合理性。实验分别对静态载荷和动态冲击进行测试,结果显示,在静态压载测试中,当100 N相似文献   

冷拌冷铺超粘纤维磨耗层研究与应用

冷拌冷铺超粘纤维磨耗层作为一种新型技术,结合了微表处的材料特点和Novachip的施工工艺,具有优异的粘结性、防裂性、防水性、耐久性、环保性和经济性。本文从该项技术原理及性能要求、施工工艺及经济和社会效益进行了阐述。     

Silica/mullite fiber composite membrane with double-layer structure for efficient sub-micrometer dust removal

Here, we developed silica/mullite fiber composite membranes with double-layer structure by a simple vacuum procedure for the removal of sub-micrometer dust. The support with three-dimensional skeleton structure exhibited high porosity (higher than 90%), low density (lower than 0.25?g/cm³) and high compressive strength (higher than 0.55?MPa) at 1000?°C. By controlling the mass ratio of silica sol to mullite fiber, we can obtain uniform and complete filtering layers with different thicknesses. The composite membranes exhibited high PM filtration efficiency with 99% for 1–10?µm, 97% for 0.5?µm and 90% for 0.3?µm. These samples had high air flow with very low pressure drop (lower than 600?Pa when airflow velocity reached 1?m/s). These results indicated that the silica/mullite fiber composite membranes were very promising for PM pollution control in the field of hot gas filtration.     

Recent Progress of Fiber Shaped Lighting Devices for Smart Display Applications—A Fibertronic Perspective

Advances in material science and nanotechnology have fostered the miniaturization of devices. Over the past two decades, the form-factor of these devices has evolved from 3D rigid, volumetric devices through 2D film-based flexible electronics, finally to 1D fiber electronics (fibertronics). In this regard, fibertronic strategies toward wearable applications (e.g., electronic textiles (e-textiles)) have attracted considerable attention thanks to their capability to impart various functions into textiles with retaining textiles' intrinsic properties as well as imperceptible irritation by foreign matters. In recent years, extensive research has been carried out to develop various functional devices in the fiber form. Among various features, lighting and display features are the highly desirable functions in wearable electronics. This article discusses the recent progress of materials, architectural designs, and new fabrication technologies of fiber-shaped lighting devices and the current challenges corresponding to each device's operating mechanism. Moreover, opportunities and applications that the revolutionary convergence between the state-of-the-art fibertronic technology and age-long textile industry will bring in the future are also discussed.     

On the design and optimization of hybrid carbon fiber reinforced polymer-steel cable system for cable-stayed bridges

This paper addresses the effective use of carbon fiber reinforced polymeric (CFRP) materials in the cable system. As the span length of cable-stayed bridges increases, several technical challenges become more dominant with traditional material. This paper mainly focuses on improving the aerodynamic performance through implementing CFRP composites in the cable system in combination with steel. In order to maximize the improvement, a genetic algorithm (GA)-based optimization procedure is developed to optimize the distribution of CFRP and steel. A numerical example is presented and the results suggest the typical composition of an optimized CFRP-steel cable system for long-span cable-stayed bridges.     

蔓越莓中膳食纤维的结构性质和功能性质研究

目的 考察蔓越莓中膳食纤维的结构性质和功能性质。方法 利用酶解法提取蔓越莓总膳食纤维、不溶性膳食纤维和可溶性膳食纤维, 并采用红外光谱和高效液相色谱测定其官能团结构和分子量, 采用质构仪和粘度计测定其凝胶性质和粘度, 同时对膳食纤维吸附亚硝酸根离子、交换阳离子、胆固醇、重金属和葡萄糖的能力进行研究。结果 总膳食纤维和不溶性膳食纤维的提取率较高, 分别为54.67%和38.70%, 膳食纤维具有凝胶和粘度的性质, 同时在功能上有吸附亚硝酸根离子, 交换阳离子, 吸收胆固醇, 重金属离子和葡萄糖的性能。结论 蔓越莓膳食纤维具有特殊的结构性质和很好的功能活性, 可以开发蔓越莓新功能食品。