A new calibration method for time delay standard and its application

A method which is used to measure time delay accurately by using a Type 900-LB slotted line is described. The accuracy for calibrating time delay of a precision coaxial air line Type 900-L is about + or - (0.4 to 0.6)ps, and for coaxial cables with VSWR less than 1.5 and time delay t less than 50ns is about + or - (3 to 5)ps. Theoretical analysis and mathematical derivation of microwave networks in cascade are given. Methods to eliminate the errors which are caused by the discontinuities and the error analysis of the measuring system are presented. Skin effect analysis of the transient characteristic of coaxial transmission line are discussed in detail. Methods to eliminate the errors which result from using the calibrated time delay standard to calibrate time interval measurement instruments are presented. The estimation of errors and formulae for correction of those errors are described

Assessing the influence of the Merzbacher Lake outburst floods on discharge using the hydrological model SWIM in the Aksu headwaters, Kyrgyzstan/NW China

Glacial lake outburst floods (GLOF) often have a significant impact on downstream users. Including their effects in hydrological models, identifying past occurrences and assessing their potential impacts are challenges for hydrologists working in mountainous catchments. The regularly outbursting Merzbacher Lake is located in the headwaters of the Aksu River, the most important source of water discharge to the Tarim River, northwest China. Modelling its water resources and the evaluation of potential climate change impacts on river discharge are indispensable for projecting future water availability for the intensively cultivated river oases downstream of the Merzbacher Lake and along the Tarim River. The semi-distributed hydrological model SWIM was calibrated to the outlet station Xiehela on the Kumarik River, by discharge the largest tributary to the Aksu River. The glacial lake outburst floods add to the difficulties of modelling this high-mountain, heavily glaciated catchment with poor data coverage and quality. The aims of the study are to investigate the glacier lake outburst floods using a modelling tool. Results include a two-step model calibration of the Kumarik catchment, an approach for the identification of the outburst floods using the measured gauge data and the modelling results and estimations of the outburst flood volumes. Results show that a catchment model can inform GLOF investigations by providing ‘normal’ (i.e. without the outburst floods) catchment discharge. The comparison of the simulated and observed discharge proves the occurrence of GLOFs and highlights the influences of the GLOFs on the downstream water balance. © 2013 The Authors. Hydrological Processes Published by John Wiley & Sons Ltd

Energy efficiency convergence across countries in the context of China's Belt and Road initiative

© 2018 Elsevier Ltd After China launched its “Belt and Road” (BR) initiative, the international community became concerned that it may worsen the environmental performance of the BR countries. Due to a lack of data for empirical testing, this paper addresses this concern through an indirect method and draws the implications of the potential impacts of China's BR initiative. This method empirically examines the effects of trade integration and regional cooperation, two major functions of the BR initiative, on energy efficiency (EE) convergence, a concept that describes the catching up process of EE across countries. A sample of 89 countries was selected to analyse the process of EE convergence from 2000 to 2014. The results indicate that although the gaps in EE among countries around the world become larger after 2010, regional cooperation may lead to a convergence process. It also finds that trade integration has a positive influence on convergence across the countries, especially among middle- and low-income countries. The results suggest that the BR initiative, through its roles in trade integration and regional cooperation, may promote EE convergence among countries. This is a desirable environmental outcome. This research also provides policy implications for both China and the other BR countries

Cloning and expression analysis of an E-class MADS-box gene from Populus deltoides

An E-class MADS-box gene, PdMADS2, was isolated from Populus deltoides Bartr. ex Marsh male floral buds by RT-PCR. As shown by relative–quantitative real-time polymerase chain reaction analysis, the expression of PdMADS2 was high in apical and floral buds, intermediate in immature xylem and rootsand low in mature leaves of adult male P. deltoides. In developing male floral buds, PdMADS2 expression was high and remained constant from July to September, increased significantly on February 6 and quickly fell to a very low level with the maturation of the flowers. In male inflorescences, PdMADS2expression was abundant in the perianth cups and inflorescence peduncles; it was not detected in mature pollen. In female inflorescences, PdMADS2 was highly expressed in both ovaries and inflorescence peduncles. Our results suggest that PdMADS2 plays an important role in the developmentof inflorescence meristems and flower organs in poplar

Re-analyzing the economic impact of a global bunker emissions charge

© 2018 Elsevier B.V. Regulating bunker emissions continues to be a challenging task, largely due to the lack of a globally coordinated scheme providing economic and political incentives to potential participating countries. This paper analyses the economic costs and benefits of imposing a global carbon tax on international bunker emissions by employing a computable general equilibrium model approach. Under the assumption of an emissions reduction of 5% below 2000 levels by 2020, we demonstrate that a global bunker emissions charge, on one hand, reduces trade volume and change trade patterns between countries and regions, while on the other hand, accelerates the adoption of energy-saving technologies and reallocates the supply of international transportation services throughout the world. The net economic impact, though negative on average, is modest compared to the benefits obtained from the emissions reduction. If revenues from a bunker emissions charge are properly distributed among countries and regions, the losses to disadvantaged countries are likely to be offset by the benefits to advantaged countries. This finding provides useful insights for policy-makers: a global bunker emissions charge could, in future, be an economically feasible strategy to reduce the increasing bunker emissions through the implementation requires more political effort and wisdom

Economic, social and environmental impacts of fuel subsidies: A revisit of Malaysia

© 2017 Elsevier Ltd Subsidizing energy has been widely used but is economically unfavorable. The Malaysian government has shown strong intention to reduce energy subsidies recently, but face challenges to prepare policy instruments to manage the impact. This study develops a Computable General Equilibrium (CGE) model with breakdown of households by income level to evaluate the potential impacts of removing energy subsidies on the Malaysian economy. It is shown that removing petroleum and gas subsidy would improve economic efficiency and increase GDP up to 0.65%. Budget deficit would be largely reduced after removing the petroleum subsidies, especially when the saved subsidy cost is not budgeted for other expenditure. Households would be worse off in most scenarios due to higher price level, but some compensation policy could make the lowest income group no worse than baseline, without harm the economy. The reduction in carbon emissions ranges 1.84–6.63% in different scenarios. The simulation results suggest Malaysia to completely remove all fuel subsidies and use the saved funding to cut budget deficit or spend on education, health and other service sector. It is also necessary to set a compensation scheme to minimize public resistance and make sure such scheme is affordable

Reply to "Comment on 'Fano resonance for Anderson Impurity Systems' "

In a recent Comment, Kolf et al. (cond-mat/0503669) state that our analysis of the Fano resonance for Anderson impurity systems [Luo et al., Phys. Rev. Lett 92, 256602 (2004)] is incorrect. Here we want to point out that their comments are not based on firm physical results and their criticisms are unjustified and invalid.Comment: 1 page, 1 figure, to appear in PR

Nitrous oxide emissions increase exponentially when optimum nitrogen fertilizer rates are exceeded in the North China plain

The IPCC assume a linear relationship between nitrogen (N) application rate and nitrous oxide (N2O) emissions in inventory reporting, however, a growing number of studies show a nonlinear relationship under specific soil-climatic conditions. In the North China plain, a global hotspot of N2O emissions, covering a land as large as Germany, the correlation between N rate and N2O emissions remains unclear. We have therefore specifically investigated the N2O response to N applications by conducting field experiments with five N rates, and high-frequency measurements of N2O emissions across contrasting climatic years. Our results showed that cumulative and yield-scaled N2O emissions both increased exponentially as N applications were raised above the optimum rate in maize (Zea mays L.). In wheat (Triticum aestivum L.) there was a corresponding quadratic increase in N2O emissions with the magnitude of the response in 2012–2013 distinctly larger than that in 2013–2014 owing to the effects of extreme snowfall. Existing empirical models (including the IPCC approach) of the N2O response to N rate have overestimated N2O emissions in the North China plain, even at high N rates. Our study therefore provides a new and robust analysis of the effects of fertilizer rate and climatic conditions on N2O emissions

Estimation of surface energy fluxes under complex terrain of Mt. Qomolangma over the Tibetan Plateau

Surface solar radiation is an important parameter in surface energy balance models and in estimation of evapotranspiration. This study developed a DEM based radiation model to estimate instantaneous clear sky solar radiation for surface energy balance system to obtain accurate energy absorbed by the mountain surface. Efforts to improve spatial accuracy of satellite based surface energy budget in mountainous regions were made in this work. Based on eight scenes of Landsat TM/ETM+ (Thematic Mapper/Enhanced Thematic Mapper+) data and observations around the Qomolangma region of the Tibetan Plateau, the topographical enhanced surface energy balance system (TESEBS) was tested for deriving net radiation, ground heat flux, sensible heat flux and latent heat flux distributions over the heterogeneous land surface. The land surface energy fluxes over the study area showed a wide range in accordance with the surface features and their thermodynamic states. The model was validated by observations at QOMS/CAS site in the research area with a reasonable accuracy. The mean bias of net radiation, sensible heat flux, ground heat flux and latent heat flux is lower than 23.6 W m−2. The surface solar radiation estimated by the DEM based radiation model developed by this study has a mean bias as low as −9.6 W m−2. TESEBS has a decreased mean bias of about 5.9 W m−2 and 3.4 W m−2 for sensible heat and latent heat flux, respectively, compared to the Surface Energy Balance System (SEBS)

Electric-field-induced phase transition of <001> oriented Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals

oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals were poled under different electric fields, i.e. Epoling=4 kV/cm and Epoling=13 kV/cm. In addition to the temperature-dependent dielectric constant measurement, X-ray diffraction was also used to identify the poling-induced phase transitions. Results showed that the phase transition significantly depends on the poling intensity. A weaker field (Epoling=4 kV/cm) can overcome the effect of random internal field to perform the phase transition from rhombohedral ferroelectric state with short range ordering (microdomain) FESRO to rhombohedral ferroelectric state with long range ordering (macrodomain) FElRO. But the rhombohedral ferroelectric to tetragonal ferroelectric phase transition originating from to polarization rotation can only be induced by a stronger field (Epoling=13 kV/cm). The sample poled at Epoling=4 kV/cm showed higher piezoelectric constant, d33>1500 pC/N, than the sample poled at Epoling=13 kV/cm.Comment: 7 pages, 2 figure