形状记忆材料中二类变体的研究

在经过训练处理具有双程形状记忆效应的记忆合金材料中,相变变体可分为两类:(1)择优取向变体;(2)自协作的变体。择优取向变体提供可逆的形状记忆效应,外应力可以促进或抑制这类变体的相变,改变其相变平衡温度;但对自协作变体的相变无重要影响。由上述观点可以解释双程形状记忆元件在相变过程中电阻—温度曲线与记忆应变—温度曲线不一致等现象。

The Similarity Transformation of Regularizing Functionals and Simularity Property of Their Fourier Transformations

Let and denote respectively the functionswhere λ≥1, The author discusses the similarity transformation of the regularizing functionals of these functions and the similar property of their Fourier transformation.

Mechanism of microwave assisted suspension magnetization roasting of oolitic hematite ore

Oolitic hematite is an iron ore resource with rich reserves,complex composition,low grade,fine disseminated particle sizes,and a unique oolitic structure.In this study,a microwave-assisted suspension magnetization roasting technology was proposed to recover and utilize the ore.The results showed that under the conditions of microwave pretreatment temperature of 1050℃ for 2 min,a magnetic concentrate with an iron grade of 58.72%at a recovery of 89.32%was obtained by microwave suspension magnetization roasting and magnetic separation.Moreover,compared with the no microwave pretreatment case,the iron grade and recovery increased by 3.17%and 1.58%,respectively.Microwave pretreatment increased the saturation magnetization of the roasted products from 24.974 to 39.236(A∙m^(2))/kg and the saturation susceptibility from 0.179×10^(−3) m^(3)/kg to 0.283×10^(−3) m^(3)/kg.Microcracks were formed between the iron and gangue minerals,and they gradually extended to the core of oolite with the increase in the pretreatment time.The reducing gas diffused from outside to inside along the microcracks,which promoted the selective transformation of the weak magnetic hematite into the strong magnetic magnetite.

THEORETIC RESEARCH ON ROBUSTIFIED LEAST SQUARES ESTIMATOR BASED ON EQUIVALENT VARIANCE-COVARIANCE

Depending on analyzing the abuse of equivalent weights,a set of self-contained theory system on robust estimation based on equivalent variance-covariance is established,which includes ρ function, φ function,equivalent variance-covariance function,influence function and breakdown point.And an example is given to verify that the robust models proposed in this paper are reliable and correct.

Crystallization, Vitrification, and Gelation of Patchy Colloidal Particles

We present the phase diagrams for neutral patchy colloidal particles whose surface is decorated by different number of identical patches,where each patch serves as an associating site.The hard-core Lennard-Jones(LJ)potential and associating interaction are incorporated into the free energies of patchy particles in phases of the uid(F),random close packing(RCP),and face-centered-cubic(FCC)crystal.A rich phase structure of patchy particles with F-F,F-RCP,and F-FCC transitions can be observed.Meanwhile,the sol-gel transition(SGT)characterizing the connectivity of patchy particles is also investigated.It is shown that,depending on the number of patches and associating energy,the F-F transition might be metastable or stable with respect to the F-RCP and F-FCC transitions.Meanwhile,the critical temperatures,critical densities,triple points,and SGT can be significantly regulated by these factors.

Simulated response of the active layer thickness of permafrost to climate change

The active layer thickness(ALT)in permafrost regions,which affects water and energy exchange,is a key variable for assessing hydrological processes,cold-region engineering,and climate change.In this study,the authors analyzed the variation trends and relative changes of simulated ALTs using the Chinese Academy of Sciences Land Surface Model(CAS-LSM)and the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System Model,gridpoint version 3(CAS-FGOALS-g3).Firstly,the simulated ALTs produced by CAS-LSM were shown to be reasonable by comparing them with Circumpolar Active Layer Monitoring observations.Then,the authors simulated the ALTs from 1979 to 2014,and their relative changes across the entire Northern Hemisphere from 2015 to 2100.It is shown that the ALTs have an increasing trend.From 1979 to 2014,the average ALTs and their variation trends over all permafrost regions were 1.08 m and 0.33 cm yr-1,respectively.The relative changes of the ALTs ranged from 1%to 58%,and the average relative change was 10.9%.The variation trends of the ALTs were basically consistent with the variation trends of the 2-m air temperature.By 2100,the relative changes of ALTs are predicted to be 10.3%,14.6%,30.1%,and 51%,respectively,under the four considered hypothetical climate scenarios(SSP-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5).This study indicates that climate change has a substantial impact on ALTs,and our results can help in understanding the responses of the ALTs of permafrost due to climate change.

Comparison between the interannual and decadal components of the Silk Road pattern

The Silk Road pattern（SRP）, which is a teleconnection pattern along the Asian upper-tropospheric westerly jet in summer, exhibits both interannual and decadal variabilities. Through the nineyear Gaussian filtering method and regression analyses, this study compares the interannual and decadal components of the SRP. The results indicate that the interannual SRP corresponds to a well-organized wave train of alternate cyclonic and anticyclonic anomalies across the Eurasian continent along the Asian westerly jet, resulting in a similar wave-like pattern of cold and warm surface temperature anomalies. This pattern of temperature anomalies differs from that associated with the original SRP, which is characterized by warmer or cooler temperatures mainly over Europe–West Asia and Northeast Asia, depending on the phase of the SRP. On the other hand, the decadal SRP shows a similar pattern to the interannual one from Europe to Central Asia, but the meridional wind anomalies tend to be weak over East Asia. These circulation anomalies are responsible for the significant temperature anomalies over Europe–West Asia and Northeast Asia but weak anomalies between these two domains.

Airborne Pollen Grains Of Afyon, Turkey

The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of them, 6 732 were identified in 1999 and 7 635 in 2000. Of the total pollen grains, 69.67% were arboreal, 26.64% non_arboreal and 3.68 % unidentified. The majority of the investigated pollen grains were from Pinus, Gramineae, Cupressaceae, Platanus , Chenopodiaceae/Amaranthaceae, Quercus, Ailanthus, Moraceae, Juglans , Salix, Cedrus and Rosaceae. The highest level of pollen grains was in May.

Effect of compression ratio on microstructure evolution of Mg−10%Al−1%Zn−1%Si alloy prepared by SIMA process

A new Mg−10%Al−1%Zn−1%Si alloy with non-dendritic microstructure was prepared by strain induced melt activation(SIMA)process.The effect of compression ratio on the evolution of semisolid microstructure of the experimental alloy was investigated.The results indicate that the average size ofα-Mg grains decreases and spheroidizing tendency becomes more obvious with the compression ratios increasing from 0 to 40%.In addition,the eutectic Mg2Si phase in the Mg−10%Al−1%Zn−1%Si alloy transforms completely from the initial fishbone shape to globular shape by SIMA process.With the increasing of compression ratio,the morphology and average size of Mg2Si phases do not change obviously.The morphology modification mechanism of Mg2Si phase in Mg−10%Al−1%Zn−1%Si alloy by SIMA process was also studied.

New Representation of Maxwell Relation

A new representation of the Maxwell relation for phase transformation is given, which is expressed in simpler form and has more direct physical meaning than the original Maxwell relation. It is shown that the physical conjecture for the so-called "lock-up" condition suggested by Jensen (1999) is correct, but the equation for the "lock-up" condition suggested by Jensen (1999) is not. Numerical examples also demonstrate that the application of the new representation of Maxwell relation gives exactly the same solutions as the ones with application of the original Maxwell relation and, however, application of the "lock-up" condition gives no real solutions.

Interannual Variability of Sea Surface Temperature in the Northern Indian Ocean Associated with ENSO and IOD

The Northern Indian Ocean （NIO） sea surface temperature （SST） warming, associated with the E1 Nifio/Southern Oscillations （ENSO） and the Indian Ocean Dipole （IOD） mode, is investigated using the International Comprehensive Ocean-Atmosphere Data Set （ICOADS） monthly data for the period 1979-2010. Statistical analy- ses are used to identify respective contribution from ENSO and IOD. The results indicate that the first NIO SST warming in September-November is associated with an IOD event, while the second NIO SST warming in spring-summer following the mature phase of ENSO is associated with an ENSO event. In the year that IOD co-occurred with ENSO, NIO SST warms twice, rising in the ENSO developing year and decay year. Both short- wave radiation and latent heat flux contribute to the NIO SST variation. The change in shortwave radiation is due to the change in cloudiness. A cloud-SST feedback plays an important role in NIO SST warming. The latent heat flux is related to the change in monsoonal wind. In the first NIO warming, the SST anomaly is mainly due to the change in the latent heat flux. In the second NIO warming, both factors are important.

Effect of Forging Ratio on Microstructure of the of the 1.5710 Grade Steel

Intensity of structural changes during forging is usually determined in dependence on the forging ratio. Forging ratio at elongation is most often calculated with use of simple relations, which are based on the change of cross section of the forged pieces. The intensity of structure development is influenced not only by the simple change of cross sections, but also by relative length of the stroke, magnitude of deformation in individual passes, manner of edging, temperature, friction and shape of anvils. The paper gives an analysis of influence of the relative length of the stroke on the forging ratio.

Interactive effect of climate warming and nitrogen deposition may shift the dynamics of native and invasive species

Aims Projections of invasive species expansion under a warmer world often do not explicitly consider the concurring nitrogen(N)deposition.It remains largely unknown how the convoluted effect of climate warming and N deposition will shift the native and invasive species dynamics.Here,we hypothesize that the concurring in creases in N and temperature would promote growth of invasive species greater than that of native species.Methods A controlled greenhouse experiment was conducted to quantify the growth response of an invasive species(Solidago canadensis L.)and a co-existing native species(Artemisia argyi Levi,et Van)under the effects of climate warming,N deposition and their interactions.Important Findings Due to the strong positive effect of N addition,the interactive effect of temperature increase and N addition resulted in an overall significant increase in growth of both in vasive and native species,demonstrating that these manipulations may make microhabitats more favorable to plant growth.However,the relative increases in biomass,height and diameter of invasive S.canadensis were signifiesntly lower than those of native A.argyi.This suggests that the vegetative growth superiority of invasive S.canadensis over the native species A.argyi is reduced by the enhanced N availability in the warmer world.Therefore,the inclusion of N deposition may mitigate the projection of invasive species S.canadensis expansion under climate warming.

An Exotic Phase Change in Dynamic Electrorheological Fluids

It is well known that constant or time-varying electric fields can induce phase changes in electrorheological(ER) fluids, from a liquid to semi-solid state, provided the field strength is larger than some critical value. We describe here an experimental and theoretical study considering yet a different class of phase changes, specifically those for an ER fluid in the presence of both shear flow and a time-varying electric field. We note that as the frequency of the field is decreased, the ER fluid will go from a liquid to an intermediate transition state, and eventually to a shear banding state. Our theoretical analysis further indicates that this phase change originates from competing effects of viscous and electrical forces. Ultimately, we conclude that it is possible to achieve various states and corresponding(desired)macroscopic properties of dynamic colloidal suspensions by adjusting the frequency of the externally applied electric field.

Dual fermion condensate and phase transition in QED_3

In this paper,we investigate the behaviors of dual fermion condensate in QED 3 under variation of temperature.By means of Dyson-Schwinger equation for the fermion propagator,we extract the dual fermion condensate and compare its behavior with the ordinary chiral fermion condensate and the chiral susceptibility.It is found that the dual fermion condensate cannot be regarded as the order parameter for the confinement-deconfinement phase transition in QED 3.Furthermore,the change of the dual fermion condensate around the chiral phase transition point observed in the present work must therefore be interpreted as solely induced by the chiral transition.

A thermally tunable terahertz bandpass filter with insulator- metal phase transition of VO_2 thin film

A terahertz bandpass filter with the sandwich structure consisting of thermally tunable vanadium dioxide(VO2) thin film,silica substrate and subwavelength rectangular Cu hole arrays is designed and theoretically analyzed.The results show that the transmittance of the filter can be actively tuned by controlling the temperature of VO2,the narrow band terahertz(THz) waves with the transmittance from 85.2% to 10.5% can be well selected at the frequency of 1.25 THz when the temperature changes from 50 ℃ to 80 ℃,and the maximum modulation depth of this terahertz bandpass filter can achieve 74.7%.