Water availability in +2°C and +4°C worlds

While the parties to the UNFCCC agreed in the December 2009 Copenhagen Accord that a 2°C global warming over pre-industrial levels should be avoided, current commitments on greenhouse gas emissions reductions from these same parties will lead to a 50?:?50 chance of warming greater than 3.5°C. Here, we evaluate the differences in impacts and adaptation issues for water resources in worlds corresponding to the policy objective (+2°C) and possible reality (+4°C). We simulate the differences in impacts on surface run-off and water resource availability using a global hydrological model driven by ensembles of climate models with global temperature increases of 2°C and 4°C. We combine these with UN-based population growth scenarios to explore the relative importance of population change and climate change for water availability. We find that the projected changes in global surface run-off from the ensemble show an increase in spatial coherence and magnitude for a +4°C world compared with a +2°C one. In a +2°C world, population growth in most large river basins tends to override climate change as a driver of water stress, while in a +4°C world, climate change becomes more dominant, even compensating for population effects where climate change increases run-off. However, in some basins where climate change has positive effects, the seasonality of surface run-off becomes increasingly amplified in a +4°C climate.     

1700°C热校准风洞

1700°C热校准风洞是一台高温、高速的稳态与动态温度校准装置.本文介绍了1700°C热校准风洞的主要性能和特点,以及为此而采取的保温与冷却相结合的结构设计、高温内壳设计和其它一些技术方法.     

-80°C低温冰柜的系统设计

进行了 - 80°C的低温冷柜的设计计算 ,该低温冰柜采用自然复叠制冷循环 ,采用R2 2 /R1 4混合工质。文中涉及了蒸发器、冷凝器、冷凝蒸发器、中间换热器、毛细管和压缩机的设计计算。这种自然复叠式低温冷柜结构简单 ,在低温医学等方面有较好的应用。     

Rethinking adaptation for a 4°C world

With weakening prospects of prompt mitigation, it is increasingly likely that the world will experience 4°C and more of global warming. In such a world, adaptation decisions that have long lead times or that have implications playing out over many decades become more uncertain and complex. Adapting to global warming of 4°C cannot be seen as a mere extrapolation of adaptation to 2°C; it will be a more substantial, continuous and transformative process. However, a variety of psychological, social and institutional barriers to adaptation are exacerbated by uncertainty and long timeframes, with the danger of immobilizing decision-makers. In this paper, we show how complexity and uncertainty can be reduced by a systematic approach to categorizing the interactions between decision lifetime, the type of uncertainty in the relevant drivers of change and the nature of adaptation response options. We synthesize a number of issues previously raised in the literature to link the categories of interactions to a variety of risk-management strategies and tactics. Such application could help to break down some barriers to adaptation and both simplify and better target adaptation decision-making. The approach needs to be tested and adopted rapidly.     

Heat conductivity of water near 4°C

The results of short-term nonsteady-state measurements do not confirm the view that the heat conductivity of water behaves abnormally in the vicinity of 4°C.Notation L thickness of the liquid layer, m - T temperature, K - q heat flux, W/m² - thermal conductivity, W/m·deg K. Indices 0 and L denote the beginning and end of the layer, respectively Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 2, pp. 339–342, August, 1980.     

Synthesis of nanocrystalline TiO2 at 100 °C

A simple gel to crystal conversion route has been followed for the preparation of TiO₂ at 80–100 °C under refluxing conditions. Freshly prepared titanium hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 6–12 h. Formation of nanocrystallites of anatase is confirmed by X-ray diffraction (XRD) study. The anatase phase converts into rutile when calcined at 700 °C for 12 h. Raman scattering experiments were also performed to confirm both anatase and rutile phases. Transmission electron microscope (TEM) investigations revealed that the average particle size is 10 nm for the anatase phase whereas it is 35 nm for the rutile polymorph.     

When could global warming reach 4°C?

The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) assessed a range of scenarios of future greenhouse-gas emissions without policies to specifically reduce emissions, and concluded that these would lead to an increase in global mean temperatures of between 1.6°C and 6.9°C by the end of the twenty-first century, relative to pre-industrial. While much political attention is focused on the potential for global warming of 2°C relative to pre-industrial, the AR4 projections clearly suggest that much greater levels of warming are possible by the end of the twenty-first century in the absence of mitigation. The centre of the range of AR4-projected global warming was approximately 4°C. The higher end of the projected warming was associated with the higher emissions scenarios and models, which included stronger carbon-cycle feedbacks. The highest emissions scenario considered in the AR4 (scenario A1FI) was not examined with complex general circulation models (GCMs) in the AR4, and similarly the uncertainties in climate-carbon-cycle feedbacks were not included in the main set of GCMs. Consequently, the projections of warming for A1FI and/or with different strengths of carbon-cycle feedbacks are often not included in a wider discussion of the AR4 conclusions. While it is still too early to say whether any particular scenario is being tracked by current emissions, A1FI is considered to be as plausible as other non-mitigation scenarios and cannot be ruled out. (A1FI is a part of the A1 family of scenarios, with 'FI' standing for 'fossil intensive'. This is sometimes erroneously written as A1F1, with number 1 instead of letter I.) This paper presents simulations of climate change with an ensemble of GCMs driven by the A1FI scenario, and also assesses the implications of carbon-cycle feedbacks for the climate-change projections. Using these GCM projections along with simple climate-model projections, including uncertainties in carbon-cycle feedbacks, and also comparing against other model projections from the IPCC, our best estimate is that the A1FI emissions scenario would lead to a warming of 4°C relative to pre-industrial during the 2070s. If carbon-cycle feedbacks are stronger, which appears less likely but still credible, then 4°C warming could be reached by the early 2060s in projections that are consistent with the IPCC's 'likely range'.     

Evolution of M23C6 phase in HR3C steel aged at 650 °C

The evolution of the morphology, composition, and particle size of the M₂₃C₆ phase in HR3C steel aged at 650 °C was analysed, by means of metallographic microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed that the Cr/Fe ratio in the M₂₃C₆ phase, in the form of irregular square and long strip, increased with the ageing time. Fe was gradually replaced by Cr in the M₂₃C₆ lattice. The M₂₃C₆ phase gradually evolved and then became stable after ageing for 2000 h.     

Climate-induced population displacements in a 4°C+ world

Massive population displacements are now regularly presented as one of the most dramatic possible consequences of climate change. Current forecasts and projections show that regions that would be affected by such population movements are low-lying islands, coastal and deltaic regions, as well as sub-Saharan Africa. Such estimates, however, are usually based on a 2°C temperature rise. In the event of a 4°C+ warming, not only is it likely that climate-induced population movements will be more considerable, but also their patterns could be significantly different, as people might react differently to temperature changes that would represent a threat to their very survival. This paper puts forward the hypothesis that a greater temperature change would affect not only the magnitude of the associated population movements, but also--and above all--the characteristics of these movements, and therefore the policy responses that can address them. The paper outlines the policy evolutions that climate-induced displacements in a 4°C+ world would require.     

A Study of the Ni-Cr-Zr System at 900°C

The phase equilibrium relations of the ternary Ni-Cr-Zr system at 900℃have been investigated by means of diffusion triple and electron probe microanalysis(EMPA) techniques.A series of tie lines and triangles have been determined, and the corresponding tentative isothermal section is presented based on the current information.     

Alumina formation and microstructural changes of aluminized CoNiCrAlY coating during high temperature exposure in the temperature range 925°C–1075°C

Abstract

MCrAlY (M = Ni, Co) coatings are commonly used on gas-turbine components as oxidation resistant overlay coatings and bondcoats for thermal barrier systems. In the present work the microstructural features and oxidation behavior of an aluminized Co-base MCrAlY-coating on a Ni-based superalloy have been investigated in the temperature range 925–1075 °C. Microstructural studies of the oxidized coatings by SEM/EBSD were complemented with numerical thermodynamic calculations using the software package ThermoCalc. In the as-received condition the outer part of the coating consisted mostly of β-(Ni,Co)Al. Formation of σ-CoCr was observed at the interface between the β-layer and the inner initial CoNiCrAlY. During high-temperature air exposure alumina based surface scales were formed but the oxidation induced Al depletion of the aluminized coating did not result in formation of the γ’-(Ni₃Al) phase. Rather, the subscale formation of Co/Cr-rich phases was observed and a direct transformation of β- into γ-Ni phase after longer times. It is expected that these subscale microstructural changes thus affect the alumina formation and growth as well as the critical aluminum depletion in a different manner as in the case of corresponding β-NiAl coatings, although a direct comparison between various coating systems was not possible on the basis of the present results.     

Heat of Formation of Calcium Aluminate Monosulfate at 25 °C

The heat of formation of calcium aluminate monosulfate, 3CaO·Al₂O₃·CaSO₄·12H₂O, at 25 °C, and of less completely hydrated samples of the same compound, was determined by the heat-of-solution method, with 2N HCl as the solvent, and 3CaO·Al₂O₃·6H₂O(c) and CaSO₄·2H₂O(c), as the reactants. The results were as follows:

A Lithium Metal Anode Surviving Battery Cycling Above 200 °C

Lithium (Li) metal electrode cannot endure elevated temperature (e.g., >200 °C) with the regular battery configuration due to its low melting point (180.5 °C) and high reactivity, which restricts its application in high-temperature Li metal batteries for energy storage and causes safety concerns for regular ambient-temperature Li metal batteries. Herein, this work reports a Li₅B₄/Li composite featuring a 3D Li₅B₄ fibrillar framework filled with metallic Li, which maintains its initial structure at 325 °C in Ar atmosphere without leakage of the liquid Li. The capillary force caused by the porous structure of the Li₄B₅ fibrillar framework, together with its lithiophilic surface, restricts the leakage of liquid metallic Li and enables good thermal tolerance of the Li₅B₄/Li composite. Thus, it can be facilely operated for rechargeable high-temperature Li metal batteries. Li₅B₄/Li electrodes are coupled with a garnet-type ceramic electrolyte (Li_6.5La₃Zr_0.5Ta_1.5O₁₂) to fabricate symmetric cells, which exhibit stable Li stripping/plating behaviors with low overpotential of ≈6 mV at 200 °C using a regular sandwich-type cell configuration. This work affords new insights into realizing a stable Li metal anode for high-temperature Li metal batteries with a simple battery configuration and high safety, which is different from traditional molten-salt Li metal batteries using a pristine metallic Li anode.     

Solubility in the ternary system fullerenol-d-uranyl sulfate-water at 25°C

The solubility in ternary systems fullerenol-d-UO₂SO₄-H₂O at 25°C was studied by the method of isothermal saturation in ampules. The diagram consists of two branches corresponding to crystallization of fullerenol-d crystal hydrate and uranyl sulfate trihydrate and contains one nonvariant point of eutonic type, corresponding to joint saturation with both crystal hydrates. The eutonic is very close to the figurative point corresponding to the binary system UO₂SO₄-H₂O at 25°C. Strongly pronounced salting-out effect is observed in the crystallization branch of fullerenol-d crystal hydrate.