Optimizing 100%‐renewable grids through shifting residential water‐heater load

A low‐carbon electricity supply for Australia was simulated, and the installed capacity of the electrical grid was optimized by shifting the electricity demand of residential electric water heaters (EWHs). The load‐shifting potential of Australia was estimated for each hour of the simulation period using a nationwide aggregate EWH load model on a 90 × 110 raster grid. The electricity demand of water heaters was shifted from periods of low renewable resource and high demand to periods of high renewable resource and low demand, enabling us to effectively reduce the installed capacity requirements of a 100%‐renewable electricity grid. It was found that by shifting the EWH load by just 1 hour, the electricity demand of Australia could be met using purely renewable electricity at an installed capacity of 145 GW with a capacity factor of 30%, an electricity spillage of 20%, and a generation cost of 15.2 ¢/kWh. A breakdown of the primary energy sources used in our scenario is as follows: 43% wind, 29% concentrated solar thermal power, and 20% utility photovoltaic. Sensitivity analysis suggested that further reduction in installed capacity is possible by increasing the load‐shifting duration as well as the volume and insulation level of the EWH tank.     

Clean hydrogen generation and storage strategies via CO2 utilization into chemicals and fuels: A review

Hydrogen becomes one of the most clean energy sources. The major issues on hydrogen are lack of practical clean and high‐temperature processes and possible practical storage of clean hydrogen. An energy intensive of clean hydrogen storage via chemical and liquid fuel production route is the current demand. This article reviewed the most recent research for hydrogen (H₂) production by using several methods, such as thermochemical process, thermal decomposition, biological approaches, electrolysis, and photocatalytic method. H₂ storage types, including physical and chemical approaches, were also reviewed. The produced H₂ was stored as valuable chemicals and fuels via CO₂ hydrogenation reaction. Reactor designs are the illustrated number of design ranging from the fixed bed to the continuous stirred tank reactor. Catalyst type, catalytic system, and the related mechanism of CO₂ hydrogenation reaction to form alcohol, alkanes, and carboxylic acid were also discussed in detail.     

Evaluation of fluctuating voltage topology with fuel cells and supercapacitors for automotive applications

To develop a single‐stage power conversion topology in which energy storage devices can be directly coupled, a fluctuating voltage topology is applied, leading to lower cost and more compactness with the absence of DC/DC converters. This paper investigates such a topology for automotive applications where fuel cells are directly connected to the DC bus of the inverter, resulting in fluctuating voltage across the DC bus. Further, a supercapacitor pack is also introduced to maintain the power capacity and voltage stability. The hybridization principle and practical application of such a topology are then discussed in the time domain and frequency domain. Furthermore, the transient power requirement is decomposed to design the size of fuel cells and supercapacitors. Simulation results from the modeling of the fuel cell‐supercapacitor powertrain demonstrate the feasibility and effectiveness of this topology. The supercapacitors can serve as a low‐pass filter for the fuel cells. In conclusion, the peak power requirement can be successfully achieved because of the lowered system impedance, and the fuel cells only need to supply the average power.     

Survey of 1012 moldy dwellings by culture fungal analysis: Threshold proposal for asthmatic patient management

Different countries have tried to define guidelines to quantify what levels of fungi are considered as inappropriate for housing. This retrospective study analyzes indoor fungi by cultures of airborne samples from 1012 dwellings. Altogether, 908 patients suffering from rhinitis, conjunctivitis, and asthma were compared to 104 controls free of allergies. Portuguese decree law no 118/2013 (PDL118), ANSES (a French environmental and health agency) recommendations, and health regulations of Besançon University Hospital were applied to determine the rates of non‐conforming dwellings, which were respectively 55.2%, 5.2%, and 19%. Environmental microbiological results and medical data were compared. The whole number of colonies per cubic meter of air was correlated with asthma (P < 0.001) and rhinitis (P = 0.002). Sixty‐seven genera and species were detected in bedrooms. Asthma was correlated to Aspergillus versicolor (P = 0.004) and Cladosporium spp. (P = 0.02). Thresholds of 300 cfu/m³ for A. versicolor or 495 cfu/m³ for Cladosporium spp. are able to discriminate 90% of the asthmatic dwellings. We propose a new protocol to obtain an optimal cost for indoor fungi surveys, excluding surface analyses, and a new guideline to interpret the results based on >1000 cfu/m³ of whole colonies and/or above threshold levels for A. versicolor or Cladosporium spp.     

The effect of external flow on the feeding currents of sessile microorganisms

Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.     

Multi-channel charge readout ASIC for X-ray detection

To solve the problem of large area and high power consumption of the traditional multi-channel charge readout circuit for X-ray detection,a new multi-channel charge readout circuit structure is presented.The circuit integrates 32 charge acquisition channels,including an integrator,a differential output buffer,a digital control logic circuit and other functional modules.The proposed structure reduces the power consumption and area by integrating the sample and hold circuit and the correlated double sampling circuit into the output buffer.In order to reduce the offset and low-frequency noise,the correlated double sampling technology has been adopted.In addition,the way of overlapping the outputs between the even and odd channels is adopted to realize continuous transmission of the multi-channel signals.The chip has been fabricated using the CMOS 0.25 μm process with the chip size of 2.87 mm×2.68 mm.Measurement results show that the power consumption of each channel is 1.5 mW under the 5.0 V voltage supply and 2.5 V reference voltage.When the integrated capacitor is 7.8 pF,the integration non-linearity is less than 0.1% and the dynamic range reaches 13 100.     

Designing novel sodium bismuth titanate lead-free incipient perovskite for piezoactuator applications

Bismuth-based lead-free incipient piezoceramics have potential in piezoactuators owing to their large strain response. However, a substantial strain hysteresis and poor temperature/frequency stability heavily restrict their practical applications. Herein, we designed a compositional inhomogeneity and constructed quenched random fields to enhance the relaxor dynamics by introducing a classical relaxor material, Ba(Zr_0.2Ti_0.8)O₃, into a nonergodic material, (Na_0.5Bi_0.5)TiO₃–0.15SrTiO₃. Intriguingly, we obtained a large piezoelectric coefficient of 602 pm/V and a narrow hysteresis of 32% at the x = 0.04 (BZT4) composition. The strain properties present a robust frequency (~2%, 1-20 Hz) and temperature stability (~13%, 25-150°C). The excellent actuating properties of BZT4 were due to a field-induced reversible ergodic relaxor-ferroelectric transformation, and the narrow hysteresis can be attributed to quick switching of the dynamic relaxor phase to external stimuli. The origin of the structural transition and salient strain performance was systematically investigated. This study provides a novel route for designing lead-free incipient perovskite with a large strain, narrow hysteresis and high stability for eco-friendly actuators.     

现代炼铁工艺及低碳发展方向分析

分析了现代高炉炼铁和非高炉炼铁(直接还原、熔融还原)工艺特点和发展现状,从多个方面比较现有生产条件下各工艺的优缺点。从能源结构、生产规模及工艺成熟度阐述高炉炼铁在当前仍是国内主流工艺,并结合当前国内外低碳发展趋势和政策要求,提出高炉工艺降低碳耗的措施,明确了以“短流程”替代“长流程”和以新能源替代碳素冶金的发展方向,以最终实现“零碳炼铁”。结合现有的国际上的能源结构调整方向,指出了氢冶金的发展方向。     

基于ANSYS的脱溶机转子结构有限元分析及优化

大豆粕低温脱溶过程中,传统脱溶机转子的辐条式端板结构易出现疲劳断裂。通过对脱溶机转子辐条式端板的结构研究,建立力学模型,采用ANSYS软件对转子辐条式端板进行有限元分析,模拟辐条各截面上应力的变化,确定端板辐条应力集中位置。为该转子端板结构的改进方案提供理论依据。