Sparse nanowire arrays for facile transport measurements

Nanowires can be electrodeposited into partially etched porous alumina templates such that only a very small number of nanowires reach the top surface of the template. This allows transport measurements of small clusters or single nanowires in their alumina matrix by connecting leads to the hemispherical domes marking the protrusion of nanowires on the surface. Copper, nickel, and silver nanowires have been synthesized in this manner, and a more general synthesis method is proposed.     

A practical approach towards mathematical modeling of deposition rate during twin-wire submerged arc welding

The present paper deals with a shop floor applicable mathematical model for deposition rate during twin-wire submerged arc welding. The salient features of this model are (1) instead of melting rate, as modeled during past investigations, it quantifies the deposition rate, which is the actual outcome of the process and always remains smaller than the melting rate because of evaporation or spatters losses and (2) it estimates electrode extension in order to predict the deposition rate which makes the proposed model more practical than the models constituted with the help of experimental measurement of electrode extension. The model is more scientific than the simplified models where contact tube to work-piece distance has been considered as the electrode extension. A critical review of the relevant past investigation is given and a mathematical model is developed for deposition rate during the twin-wire welding with both the polarities, i.e., direct current electrode positive and direct current electrode negative. The model is calibrated using the results of 200 experimental runs and it is found to be very accurate with very high coefficient of regression and admissible standard error. The developed model is further validated with extra experimental runs. The practicality of the considered approach for prediction of deposition rate can further be used in future research for other consumable arc welding processes.     

Anthropogenic I in the atmosphere: Overview over major sources, transport processes and deposition pattern

Wet and, to a lesser extent, dry deposition of atmospheric ¹²⁹I are known to represent the dominating processes responsible for ¹²⁹I in continental environmental samples that are remote from ¹²⁹I sources and not directly influenced by any liquid ¹²⁹I release of nuclear installations. Up to now, however, little is known about the major emitters and the related global deposition pattern of ¹²⁹I.In this work an overview over major sources of ¹²⁹I is given, and hitherto unknown time-dependent releases from these were estimated. Total gaseous ¹²⁹I releases from the US and former Soviet reprocessing facilities Hanford, Savannah River, Mayak, Seversk and Zheleznogorsk were found to have been 0.53, 0.27, 1.05, 0.23 and 0.14 TBq, respectively. These facilities were thus identified as major airborne ¹²⁹I emitters.The global deposition pattern due to the ¹²⁹I released, depending on geographic latitude and longitude, and on time was studied using a box model describing the global atmospheric transport and deposition of ¹²⁹I. The model predictions are compared to ¹²⁹I concentrations measured by means of Accelerator Mass Spectrometry (AMS) in water samples that were collected from various lakes in Asia, Africa, America and New Zealand, and to published values.As a result, both pattern and temporal evolution of ¹²⁹I deposition values measured in and calculated for different types of environmental samples are, in general, in good agreement. This supports our estimate on atmospheric ¹²⁹I releases and the considered substantial transport and deposition mechanisms in our model calculations.     

Effects of ventilation strategies and source locations on indoor particle deposition

A computer model for predicting aerosol dispersion in indoor spaces was validated with experimental data found in the literature. The validated model was used to explore the effect of the area or point source locations on aerosol particle transportation in ventilation rooms with rough surfaces. Two different ventilation strategies were studied: mixing ventilation (MV) and underfloor air distribution (UFAD) system. The simulation results show that in MV, the particle concentration and removal effectiveness are little dependent on the position of the pollutant sources. In UFAD, the source location has a strong impact on the distribution and removing of the contaminants. The particle removal performance strongly depends on the ventilation efficiency and the particle deposition loss in the room with rough surfaces. The important consideration in both the relative ventilation efficiency and the deposition rate is the relative position of the sources to the main airflow and the occupied zone in an UFAD room.     

Study on ash deposition under oxyfuel combustion of coal/biomass blends

Combustion in an O₂/CO₂ mixture (oxyfuel) has been recognized as a promising technology for CO₂ capture as it produces a high CO₂ concentration flue gas. Furthermore, biofuels in general contribute to CO₂ reduction in comparison with fossil fuels as they are considered CO₂ neutral. Ash formation and deposition (surface fouling) behavior of coal/biomass blends under O₂/CO₂ combustion conditions is still not extensively studied. Aim of this work is the comparative study of ash formation and deposition of selected coal/biomass blends under oxyfuel and air conditions in a lab scale pulverized coal combustor (drop tube). The fuels used were Russian and South African coals and their blends with Shea meal (cocoa). A horizontal deposition probe, equipped with thermocouples and heat transfer sensors for on line data acquisition, was placed at a fixed distance from the burner in order to simulate the ash deposition on heat transfer surfaces (e.g. water or steam tubes). Furthermore, a cascade impactor (staged filter) was used to obtain size distributed ash samples including the submicron range at the reactor exit. The deposition ratio and propensity measured for the various experimental conditions were higher in all oxyfuel cases. The SEM/EDS and ICP analyses of the deposit and cascade impactor ash samples indicate K interactions with the alumina silicates and to a smaller extend with Cl, which was all released in the gas phase, in both the oxyfuel and air combustion samples. Sulfur was depleted in both the air or oxyfuel ash deposits. S and K enrichment was detected in the fine ash stages, slightly increased under air combustion conditions. Chemical equilibrium calculations were carried out to facilitate the interpretation of the measured data; the results indicate that temperature dependence and fuels/blends ash composition are the major factors affecting gaseous compounds and ash composition rather than the combustion environment, which seems to affect the fine ash (submicron) ash composition, and the ash deposition mechanisms.     

Performance and Evaluation of Cu‐based Nano‐composite Anodes for Direct Utilisation of Hydrocarbon Fuels in SOFCs

The anodes for direct utilisation of hydrocarbon fuels have been developed by using Cu/Ceria‐based nano‐composite powders. The CuO/GDC/YSZ–YSZ or CuO/GDC‐GDC nano‐composite powders were synthesised by coating nano‐sized CuO and CeO₂ particles on the YSZ or GDC core particles selectively by the Pechini process. Their microstructures and electrical properties have been investigated with long‐term stability in reactive gases of dry methane and air. The anodes fabricated using Cu‐based nano‐composite anodes showed almost no carbon deposition until 500 h in dry CH₄ atmosphere. The type of an electrolyte‐supported single cell in conjunction with the Cu/Ceria‐based anode must be selected together for the low melting temperature of Cu/CuO. The GDC electrolyte supported unit cell with the Cu/GDC–GDC anode showed the maximum power density of 0.1 Wcm^–2 and long‐term stability for more than 500 h under electronic load of 0.05 Acm^–2 at 650 °C in dry methane atmosphere.     

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东部地区区块评价与优选及相关研究表明，箕状断陷盆地可分为早、中、晚期断陷、坳陷和萎缩隆升五个演化阶段。不同阶段，其变形和沉积充填特征不一。断陷早期，构造坡折带不发育，以干旱的冲积—滨浅湖沉积体系为主；断陷中期，发育单断式构造坡折带，以比较湿润的冲积—滨浅湖—半深湖沉积体系为主；断陷晚期是断陷湖盆扩张的鼎盛时期，发育多断式构造坡折带，以湿润的滨浅湖—深湖相沉积体体系为主；坳陷期，构造稳定，地势平坦，相类型比较齐全；萎缩阶段，湖盆遭受强烈的剥蚀，沉积基本缺失。文章最后指出，中、晚期断陷和坳陷〖JP3〗阶段是盆地烃源岩和储集层发育的黄金时期，经历了这三个演化阶段的成熟和过成熟箕状断陷的油气勘探前景较好。     

Ultrasonic spray deposition for production of organic solar cells

Recent improvements of organic photovoltaic power conversion efficiencies have motivated development of scalable processing techniques. We compare chlorobenzene and p-xylene, as solvents with similar bulk properties, in a case study of ultrasonic spray depositions of bulk heterojunction layers in photovoltaic devices. Structure and morphology of spray-deposited films are investigated via small-angle X-ray diffraction and optical microscopy. Unique phases are observed in bulk heterostructure films sprayed from p-xylene. Films sprayed from chlorobenzene resulted in higher device efficiencies than p-xylene due to large differences in film morphologies. Carrier loss mechanisms are also investigated. Post-production annealing increases power conversion efficiency to 3.2% when chlorobenzene is used.     

Investigation of electroless copper plating on polyurethane foam,as an initial step of open cell foam production process

Abstract

Coating of polymeric foams is known as a method for production of metallic foams, which produces foams with high volume of porosity and controllable pore size. In this research, this method was employed to produce open cell copper foam by use of polyurethane foam with an average pore size of 0.4?mm as the substrate. Since polyurethane foam as a non-conductive material is not able to be coated directly by electrolytic deposition, the substrate was initially metallised by electroless copper plating. In the electroless plating process, the effects of the main parameters such as bath chemical composition, solution pH and temperature on deposition rate and thickness of the coatings obtained were investigated. The results showed that the optimum condition of the process is obtained when CuSO₄ concentration in the deposition bath is 12?g?L^??1, pH is 13 and plating temperature range is 55–60°C.