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•Coal combustion, ASHP, solar heating, gas furnace and electric heating are compared.•Thermal comfort, economic, energy consumption and environmental benefit are evaluated.•Different ...PMV-PPD are set, and the design thermal index is amended.•The optimal heating mode of rural buildings in cold areas is found.
In recent years, space heating modes are diversified. In the early stage of space heating design, we should reasonably evaluate and optimize the heating mode in order to get a better heating effect. In the past, the evaluation of different heating modes was mostly single evaluation. In this paper, the thermal comfort, economic, energy consumption and environmental benefit are comprehensively evaluated. Four heating modes in the “Coal to electricity” project of China are compared with coal combustion. The modes are ASHP (Air Source Heat Pump), solar heating, gas furnace and electric heating. Based on PMV-PPD, a more reasonable design thermal index of 35.18 W/m2 is obtained. The matched capacity and operation of heating system are optimized. The results show that ASHP combined with floor radiation heating is the best space heating mode in cold areas of China. The comprehensive rate of the four evaluations is 89.64%, and its thermal comfort is the best. For a 120 m2 house in Lanzhou, after the transformation of traditional coal burning heating mode, the static payback period is 6.9 years. The actual energy consumption reduction of society is 2,769 kg/year. The reduction of CO2 emissions is 4,014 kg/year.
A computational hydrodynamics method was formulated and implemented for horizontal axis tidal turbines. This paper presents a comparative analysis between screw propellers and horizontal axis ...turbines, in terms of geometry and motion parameters, inflow velocity analysis and the implementation methodologies. Comparison and analysis are given for a marine propeller model and a horizontal axis turbine model that have experimental measurements available in literature. Analysis and comparison are presented in terms of thrust coefficients, shaft torque/power coefficients, blade surface pressure distributions, and downstream velocity profiles. The effect of number of blades from 2 to 5, of a tidal turbine on hydrodynamic efficiency is also obtained and presented. The key implementation techniques and methodologies are provided in detail for the propeller based panel method tool to migrate as a prediction tool for tidal turbine. While the method has been proven to be accurate and robust for many propellers tested in the past, this numerical tool could be validated further for turbines. To further refine and validate the panel method for various turbines, it requires substantial additional experimental measurements. These measurements include downstream velocity profile by using LDV and/or SPIV, which are essential for numerical wake vortices descritization.
This paper proposes a new variational pansharpening model with joint spectral and spatial consistency priors, which aims to fuse a low resolution (LR) multispectral (MS) image and a high resolution ...(HR) panchromatic (Pan) image to produce a pan-sharpened HR MS image. Specifically, the proposed model combines three consistency terms into a unified variational framework, which are (1) Local spectral consistency fidelity term, which enforces the degradation relation-based local spectral consistency constraint between the HR MS and LR MS images; (2) Hessian feature-enforced spatial consistency prior term, which particularly models the Hessian feature consistency constraint between the HR MS and Pan images to enforce spatial consistency; and (3) Wavelet-based spectral-spatial consistency prior term, which models the consistency between the HR MS image and the constructed Wavelet-based matching image to enforce spectral-spatial consistency. Moreover, the proposed model is efficiently solved by designing an optimization algorithm under the forward-backward splitting framework. Finally, experiments on the QuickBird, Pleiades and GeoEye-1 satellite datasets systematically illustrate that the proposed method performs better spectral and spatial qualities than various compared methods.
Considering the risk aversion characteristics of supply chain members, how to effectively design the government subsidy strategy and green supply chain strategy is a realistic and urgent issue. ...Regarding this, we optimize and compare four three-stage Stackelberg game models between government and a two-echelon green supply chain, namely both manufacturer and retailer risk neutral (BN), manufacturer risk aversion while retailer risk neutral (MA), retailer risk aversion while manufacturer risk neutral (RA) and both manufacturer and retailer risk aversion (BA). The government as the leader decides the subsidy rate of green input cost with the goal of maximizing social welfare; the manufacturer as the first follower makes decisions on product greenness and wholesale price to maximize its own interests; and the retailer as the second follower determines retail prices to maximize its own interests. Employing mathematical reasoning and numerical simulation investigate thoroughly the effects of the government subsidies and the members' risk aversion. Results indicate that an appropriate government subsidy investment has a positive effect on optimal decisions and related benefits. Risk aversion is in favor of improvement of product greenness and social welfare while reduction of retail price. With the increase of manufacturer risk aversion, green subsidy investment rate and retailer expected revenue increase; on the contrary, the wholesale price and manufacturer expected revenue decrease. With the increase of retailer risk aversion, the wholesale price and manufacturer expected revenue increase, while green subsidy investment rate and retailer expected revenue decrease. In the model of BN, product greenness and social welfare are the lowest, while retail price is the highest. BA is opposite to BN. In the model of RA, green subsidy investment rate and retailer expected revenue the lowest, while wholesale price and manufacturer expected revenue the highest. RA is opposite to MA. The government should formulate appropriate subsidy policies to encourage manufacturers to produce green products and raise consumers' green awareness. Enterprises should control their own risk aversion and assess the risk aversion of the other party reasonably.
The mixed halide perovskites have emerged as outstanding light absorbers for efficient solar cells. Unfortunately, it reveals inhomogeneity in these polycrystalline films due to composition ...separation, which leads to local lattice mismatches and emergent residual strains consequently. Thus far, the understanding of these residual strains and their effects on photovoltaic device performance is absent. Herein we study the evolution of residual strain over the films by depth-dependent grazing incident X-ray diffraction measurements. We identify the gradient distribution of in-plane strain component perpendicular to the substrate. Moreover, we reveal its impacts on the carrier dynamics over corresponding solar cells, which is stemmed from the strain induced energy bands bending of the perovskite absorber as indicated by first-principles calculations. Eventually, we modulate the status of residual strains in a controllable manner, which leads to enhanced PCEs up to 20.7% (certified) in devices via rational strain engineering.
Tidal turbine rotor blade fractures and failures have resulted in substantial damage and hence cost of repair and recovery. The present work presents a rotor blade design and optimization method to ...address the blade structural strength design problem. The generic procedure is applicable to both turbine rotors and propellers. The optimization method seeks an optimum blade thickness distribution across the span with a prescribed constant safety factor for all the blade sections. This optimization procedure serves two purposes: while maintaining the required structural strength and integrity for an ultimate inflow speed, it aims to reduce the material to a minimum and to maintain power generation efficiency or improve the hydrodynamic efficiency. The value of the chosen minimum safety factor depends on the actual working conditions of the turbine in which the sectional peak loading and frequency are used: the harsher the environment, the larger the required safety factor. An engineering software tool with both hydrodynamic and structural capabilities was required to predict the instantaneous loading acting on all the blade sections, as well as the strength of a local blade section with a given blade geometry and chosen material. A time-domain, 3D unsteady panel method was then implemented based on a marine propeller software tool and used to perform the optimization. A 3-blade 20-m tidal turbine that was prototyped in parallel with the current work for the Bay of Fundy was used as an example for optimization. The optimum thickness distribution for a required safety factor at the ultimate possible inflow speed resulted in 37.6% saving in blade material. The blade thickness and distribution as a function of a maximum inflow speed of 6 m/s is also presented. The blade material used in the example was taken as nickel–aluminium–bronze (NAB) but the procedure was developed to be applicable to propeller or turbine blades of basically any material.
► A generic procedure was established to address a remaining problem that has lead to rotor blade fractures and failures. ► This manuscript presents also a design-optimization example for a 20 m rotor targeted at the Bay of Fundy, NS Canada. ► The new procedure suggests the inflow speed for strength evaluation be the extreme in the harsh environment. ► The finalized blade thickness design is 5 times stronger at the new speed specification for the Bay of Fundy. ► The new procedure saved 86 tonnes (37.6%) materials in the design example for NAB ($17 M saving at $200/kg).
Abstract
Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation ...of sulfur dioxide (SO
2
) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO
2
oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO
2
by nitrogen dioxide (NO
2
) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N
2
O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO
2
by NO
2
, producing HONO which can in turn oxidize SO
2
to yield N
2
O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.
Earth-abundant first-row (3d) transition metal–based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials substantially above thermodynamic ...requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxyhydroxides materials with an atomically homogeneous metal distribution. These gelled FeCoW oxyhydroxides exhibit the lowest overpotential (191 millivolts) reported at 10 milliamperes per square centimeter in alkaline electrolyte. The catalyst shows no evidence of degradation after more than 500 hours of operation. X-ray absorption and computational studies reveal a synergistic interplay between tungsten, iron, and cobalt in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER.
Microbial and viral communities transform the chemistry of Earth's ecosystems, yet the specific reactions catalyzed by these biological engines are hard to decode due to the absence of a scalable, ...metabolically resolved, annotation software. Here, we present DRAM (Distilled and Refined Annotation of Metabolism), a framework to translate the deluge of microbiome-based genomic information into a catalog of microbial traits. To demonstrate the applicability of DRAM across metabolically diverse genomes, we evaluated DRAM performance on a defined, in silico soil community and previously published human gut metagenomes. We show that DRAM accurately assigned microbial contributions to geochemical cycles and automated the partitioning of gut microbial carbohydrate metabolism at substrate levels. DRAM-v, the viral mode of DRAM, established rules to identify virally-encoded auxiliary metabolic genes (AMGs), resulting in the metabolic categorization of thousands of putative AMGs from soils and guts. Together DRAM and DRAM-v provide critical metabolic profiling capabilities that decipher mechanisms underpinning microbiome function.
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