Varying the performance of helical auxetic yarns by altering component properties and geometry

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.This paper presents a systematic study of the helical auxetic yarn (HAY) via careful in-house fabrication and characterisation of a wide range of polymeric fibres and yarns. It provides a better understanding of the auxetic behaviour of the HAY in order to tailor their properties for specific applications. The study focused on three parameters: component moduli, the core/wrap diameter ratio and the initial wrap angle. The results show that a larger difference in component moduli, a higher core/wrap diameter ratio and a lower initial wrap angle can produce a larger maximum negative Poisson's ratio value and thereby a better auxetic performance for HAYs. All three parameters could be carefully utilised when in combination to achieve the required auxetic behaviour of HAYs. Moreover, the instantaneous true Poisson's ratio analysis accurately presents the instantaneous behaviour of highly strain dependent HAYs.This work is supported by the UK Engineering and Physical Science Research Council (EPSRC Grant No. EP/J004553/1). The authors would like also to acknowledge their colleagues Dave Baker and Yat-Tarng Shyng for technical support

No spin-localization phase transition in the spin-boson model without local field

We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition (QPT) happening between the localized and delocalized phases, and the behavior of the model can be fully characterized by the even or odd parity as well as the parity breaking, instead of the QPT, owned by the ground state of the system. Our analytical treatment about the eigensolution of the ground state of the model presents for the first time a rigorous proof of no-degeneracy for the ground state of the model, which is independent of the bath type, the degrees of freedom of the bath and the calculation precision. We argue that the QPT mentioned previously appears due to unreasonable treatment of the ground state of the model or of the infrared divergence existing in the spectral functions for Ohmic and sub-Ohmic dissipations.Comment: 5 pages, 1 figure. Comments are welcom

Simulation of alnico coercivity

Micromagnetic simulations of alnico show substantial deviations from Stoner-Wohlfarth behavior due to the unique size and spatial distribution of the rod-like Fe-Co phase formed during spinodal decomposition in an external magnetic field. The maximum coercivity is limited by single-rod effects, especially deviations from ellipsoidal shape, and by interactions between the rods. Both the exchange interaction between connected rods and magnetostatic interaction between rods are considered, and the results of our calculations show good agreement with recent experiments. Unlike systems dominated by magnetocrystalline anisotropy, coercivity in alnico is highly dependent on size, shape, and geometric distribution of the Fe-Co phase, all factors that can be tuned with appropriate chemistry and thermal-magnetic annealing

Pricing Carbon Emissions in China

The purpose of the paper is to provide a clear mechanism for determining carbon emissions pricing in China as a guide to how carbon emissions might be mitigated to reduce fossil fuel pollution. The Chinese Government has promoted the development of clean energy, including hydroelectric power, wind power, and solar energy generation. In order to involve companies in carbon emissions control, a series of regional and provincial carbon markets have been established since 2013. Since China’s carbon market was established in 2013 and mainly run domestically, and not necessarily using market principles, there has been almost no research on China’s carbon price and volatility. This paper provides an introduction to China’s regional and provincial carbon markets, proposes how to establish a national market for pricing carbon emissions, discusses how and when these markets might be established, how they might perform, and the subsequent prices for China’s regional and national carbon markets. Power generation in manufacturing consumes more than other industries, with more than 40% of total coal consumption. Apart from manufacturing, the northern China heating system also relies on fossil fuels, mainly coal, which causes serious pollution. In order to understand the regional markets well, it is necessary to analyze the energy structure in these regions. Coal is the primary energy source in China, so that provinces that rely heavily on coal receive a greater number of carbon emissions permits from the Chinese Government. In order to establish a national carbon market for China, a detailed analysis of eight important regional markets will be presented. The four largest energy markets, namely Guangdong, Shanghai, Shenzhen and Hubei, traded around 82% of the total volume and 85% of the total value of the seven markets in 2017, as the industry structure of the western area is different from that of the eastern area. The China National Development and Reform Commission has proposed a national carbon market, which can attract investors and companies to participate in carbon emissions trading. This important issue will be investigated in the paper

Testing Spatial Noncommutativity via Magnetic Hyperfine Structure Induced by Fractional Angular Momentum of Rydberg System

An approach to solve the critical problem of testing quantum effects of spatial noncommutativity is proposed. Magnetic hyperfine structures in a Rydberg system induced by fractional angular momentum originated from spatial noncommutativity are discussed. The orders of the corresponding magnetic hyperfine splitting of spectrum $\sim 10^{-7} - 10^{-8} eV$ lie within the limits of accuracy of current experimental measurements. Experimental tests of physics beyond the standard model are the focus of broad interest. We note that the present approach is reasonable achievable with current technology. The proof is based on very general arguments involving only the deformed Heisenberg-Weyl algebra and the fundamental property of angular momentum. Its experimental verification would constitute an advance in understanding of fundamental significance, and would be a key step towards a decisive test of spatial noncommutativity.Comment: 11 pages, no figure

Establishing National Carbon Emission Prices for China

The purpose of the paper is to establish national carbon emissions prices for the People’s Republic of China, which is one of the world’s largest producers of carbon emissions. Several measures have been undertaken to address climate change in China, including the establishment of a carbon trading system. Since 2013, eight regional carbon emissions markets have been established, namely Beijing, Shanghai, Guangdong, Shenzhen, Tianjin, Chongqing, Hubei and Fujian. The Central Government announced a national carbon emissions market, with power generation as the first industry to be considered. However, as carbon emissions prices in the eight regional markets are very different, for a variety of administrative reasons, it is essential to create a procedure for establishing a national carbon emissions price. The regional markets are pioneers, and their experience will play important roles in establishing a national carbon emissions market, with national prices based on regional prices, turnovers and volumes. The paper considers two sources of regional data for China’s carbon allowances, which are based on primary and secondary data sources, and compares their relative strengths and weaknesses. The paper establishes national carbon emissions prices based on the primary and secondary regional prices, for the first time, and compares both national prices and regional prices against each other. The carbon emission prices in Hubei, Guangdong, Shenzhen and Tianjin are highly correlated with the national prices based on the primary and secondary sources. Establishing national carbon emissions prices should be very helpful for the national carbon emissions market that is under construction in China, as well as for other regions and countries worldwide

The Importance of Disk Structure in Stalling Type I Migration

As planets form they tidally interact with their natal disks. Though the tidal perturbation induced by Earth and super-Earth mass planets is generally too weak to significantly modify the structure of the disk, the interaction is potentially strong enough to cause the planets to undergo rapid type I migration. This physical process may provide a source of short-period super-Earths, though it may also pose a challenge to the emergence and retention of cores on long-period orbits with sufficient mass to evolve into gas giants. Previous numerical simulations have shown that the type I migration rate sensitively depends upon the circumstellar disk's properties, particularly the temperature and surface density gradients. Here, we derive these structure parameters for 1) a self-consistent viscous-disk model based on a constant \alpha-prescription, 2) an irradiated disk model that takes into account heating due to the absorption of stellar photons, and 3) a layered-accretion disk model with variable \alpha-parameter. We show that in the inner viscously-heated regions of typical protostellar disks, the horseshoe and corotation torques of super-Earths can exceed their differential Lindblad torque and cause them to undergo outward migration. However, the temperature profile due to passive stellar irradiation causes type I migration to be inwards throughout much of the disk. For disks in which there is outwards migration, we show that location and the mass range of the "planet traps" depends on some uncertain assumptions adopted for these disk models. Competing physical effects may lead to dispersion in super-Earths' mass-period distribution.Comment: 12 pages, Submitted to Ap

Which is better to preserve pulmonary function: Short-term or prolonged leukocyte depletion during cardiopulmonary bypass?

ObjectivesNeutrophils are crucial in the development of acute lung injuries during cardiopulmonary bypass. However, the efficacy of leukocyte depletion on pulmonary protection remains controversial, possibly owing to different filtration strategies used in the literature. In this study, we investigated whether short-term leukocyte depletion strategy is more efficacious than prolonged leukocyte depletion in preserving pulmonary function.MethodsEighteen adult dogs were randomized equally into 3 groups. Leukocyte-depleting filters were used for 10 minutes in the LD-S group, throughout cardiopulmonary bypass in the LD-T group, and not used in the control group. Neutrophil counts, elastase, and interleukin-8 concentrations in plasma, myeloperoxidase and interleukin-8 concentrations in pulmonary tissue, and pulmonary vascular resistance and oxygen index were determined to evaluate the inflammatory response and damage to pulmonary function.ResultsAlthough the neutrophil count and pulmonary parenchymal myeloperoxidase contents were significantly lower in both LD-S and LD-T groups than that in the control group, lower pulmonary parenchymal interleukin-8 level, lower pulmonary vascular resistance (113 ± 33 dyne · s/cm5), higher oxygen index (366 ± 82.3 mm Hg), and thinner alveolus wall thickness were seen only in the LD-S group, and the pulmonary parenchymal interleukin-8 levels were also lower in the LD-S group after cardiopulmonary bypass. The plasma elastase and interleukin-8 levels were significantly lower in the LD-S group, but they were significantly higher in the LD-T group compared with the control group after cardiopulmonary bypass.ConclusionsShort-term rather than prolonged leukocyte depletion during cardiopulmonary bypass appears to be more efficacious in protecting pulmonary function via attenuation of the extracorporeal circulation–induced inflammatory response

Faint young Sun paradox remains

The Sun was fainter when the Earth was young, but the climate was generally at least as warm as today; this is known as the `faint young Sun paradox'. Rosing et al. [1] claim that the paradox can be resolved by making the early Earth's clouds and surface less reflective. We show that, even with the strongest plausible assumptions, reducing cloud and surface albedos falls short by a factor of two of resolving the paradox. A temperate Archean climate cannot be reconciled with the low level of CO2 suggested by Rosing et al. [1]; a stronger greenhouse effect is needed.Comment: 3 pages, no figures. In press in Nature. v2 corrects typo in author list in original submissio