Variations of Frost-free Period and Its Impact on Grain Yields in Henan Province during 1961-2013

The aim of this study was to investigate the responses of frost dates to global warming and its influences on grain yields. In this study, based on the frost date series defined by daily minimum ground temperature, the spatial and temporal characteristics of first frost date （FFD）, last frost date （LFD） and frost-free period （FFP） were analyzed. The impact of extending FFP on major crop yields was also studied. The results were as follows： FFD showed a significantly delaying trend of 2.2 d/10 y, and LFD presented an advancing trend of 2.4 d/10 y. FFP extended at a rate of 4.5 d/10 y due to the later FFD and earlier LFD. The most obvious trend of FFD was in westem Henan, while the most significant trend of LFD and FFP oc- curred in south central parts of the study area. However, in eestem region, the trends of FFD, LFD and FFP were not so obvious. Major crop yield showed a sig- nificant correlation with frost-free period for Henan during 1961-2013. The yields of grain, rice, wheat, and maize increased by 79.5, 90.0, 79.5 and 70.5 kg/hm2 with FFP extending by one day.

Improving grain appearance of erect-panicle japonica rice cultivars by introgression of the null gs9 allele

The panicle architecture and grain size of rice affect not only grain yield but also grain quality,especially grain appearance.The erect-panicle(EP)trait controlled by the qpe9-1/dep1 allele has been widely used in high-yielding japonica rice breeding,but usually accompanied with moderate appearance of milled rice.The null gs9 allele shows a good potential for improving grain shape and appearance.However,GS9 and qPE9-1/DEP1 loci are tightly linked,and their interaction is unclear,which obviously restricts their utilization in modern rice breeding.In the present study,comparative analyses of protein and mRNA levels revealed that GS9 and qPE9-1 function independently.Three nearisogenic lines(NILs)carrying various allelic combinations of these two loci,NIL(gs9/qpe9-1),NIL(GS9/qPE9-1)and NIL(gs9/qPE9-1),in the EP japonica cultivar 2661(GS9/qpe9-1)background were developed for genetic interaction analysis.GS9 and qPE9-1 had additive effects on determining grain size,and the null gs9 allele could decrease grain chalkiness and improve grain appearance without affecting plant and panicle architecture in EP japonica cultivars.Additionally,introgression lines(ILs)developed in another released EP japonica cultivar Wuyujing 27(WYJ27)background showed the same additive effect and the feasibility of utilizing the gs9 allele to improve grain appearance quality in high-yielding EP cultivars.This study provides an effective strategy for rice breeders to improve rice grain appearance in EP japonica and related cultivars.

Grain selection and growth orientation of prior-β phase for Ti-6-4 during additive manufacturing:insights from a modeling perspective

The microstructure of Ti-6-4 components produced by additive manufacturing suffers from the coarse and elongated prior-β grain,which leads to a decrease of the tensile behavior and the occurrence of anisotropy.To understand and control the grain evolution,a multiscale simulation is applied to investigate the relationship between the grain selection,growth orientation,and the molten pool morphology with the different deposition layer numbers and processing parameters.The accuracy of the simulation is validated by experiments in both qualitative and quantitative ways.Results show that when the grain with unfavorable orientation loses the competitive growth with its neighbors,there will be a great chance that the blocked grain is eliminated in the following layer-and-layer deposition,which leads to the increase of the grain width.The size of the molten pool increases remarkably as the layer number increases,which lays a heavy burden on the stability of the molten pool.The analytical relationship between the molten pool morphology and the grain growth orientation is also deduced.The flat molten pool causes the grains with the <001> direction close to the building direction to have greater survival potential.Besides,decreasing the line power energy shows little effect on the stability of the molten pool and the grain growth orientation,especially when the deposited layer number is large.The revealing mechanisms will help in understanding and further controlling the grain evolution.

A dataset of agro-meteorological disasteraffected area and grain loss in China(1949–2015)

As a big agricultural country,the People’s Republic of China has experienced a series of natural disasters since its founding,such as the 1959–1961 Great Famine,the 1998 floods and the 2008 snowstorm.Here we present a dataset summarizing four categories of meteorological disasteraffected area at provincial level in China from 1949 to 2015:mildly-affected area,moderately-affected area,heavily-affected area,and total affected area.Based on crop-planting data and natural disaster data,grain losses are also evaluated by using a grain loss assessment model.The dataset plays an important role in the future prediction,prevention,and reduction of agrometeorological disasters.

A Simple,Efficient and Rapid Method for Good Quality DNA Extraction from Rice Grains

An efficient and good DNA extraction protocol should be simple, affordable and yield enough DNA with high quality. Rice(Oryza sativa L.) DNA extraction methods often use seedlings or leaves rather than the grains and tend to be time-consuming, involve multiple steps, and use hazardous chemicals and expensive enzymes. Rice grains offer several benefits over seedlings and leaves as a source of DNA for genetic analysis. However, these benefits are underutilized because the bulk of a rice grain is made up of starch. It is particularly important, but difficult to get rid of the starch while extracting DNA from rice grains. This co-precipitated polysaccharide is a known inhibitor of DNA polymerase activity in polymerase chain reaction(PCR). We describe here a very simple and highly affordable Chelex~?-100 based DNA extraction method from rice grains. It does not require any hazardous chemicals or enzymes. This method reproducibly extracts DNA with good purity indices(A_(260)/A_(230) and A_(260)/A_(280) values), but requires only a few steps.

Analysis of microstructure and performance of temper bead welded joints for SA508-3 steel by Quenching and Tempering mode

The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows that tempering sorbite which has excellent overall performance was obtained in both modes. The microstructure of Quenching and Tempering mode welded joints got more fine grain. Even though the hardness of tempering bead welded joints is higher than the general one,it still meets the standards which is lower than 350 HV. The impact absorbing energy of each district of tempering bead welded joints HAZ reached 170 J,which is equal to general one.

Effect of Pyrophyllite Particle Size on Properties of AI_2O_3-SiC-C Bricks for Iron Ladles

The Al2O3 -SiC-C bricks for iron ladles were pre-pared asing bauxite, fused corundum,pyrophyllite, SiC powder and flake graphite as main starting materials, and phenolic resin as binder. The effect of pyroph,yllite particle size on permanent change in dimensions, cold crushing strength, oxidation resistance, and corrosion resistance of Al2O3 - SiC - C bricks was investigated. The results show that with the decrease of the pyrophyllite particle size, the permanent change in dimensions of Al2O3 - SiC - C bricks decreases, cold crushing strength increases, the oxidation resistance at 1400 ℃ increases, and the corrosion resistance at 1500℃ decreases.

Microstructural evolution of pre-twinned Mg alloy with annealing temperature and underlying boundary migration mechanism

This study investigates the variations in the microstructural characteristics of a pre-twinned Mg alloy with the temperature of the subsequent annealing treatment.To this end,a rolled AZ31 alloy is compressed to 3%plastic strain along the rolling direction(RD)to activate{10-12}twinning and is subsequently annealed at 200,250,300,350,and 400℃.Numerous{10-12}twins are formed throughout the compressed material,leading to the formation of a RD-oriented texture.At an annealing temperature of 200℃,no microstructural variations occur during annealing.As the annealing temperature increases from 250 to 400℃,the residual strain energy and remaining twin boundaries of the annealed material decrease owing to the promoted static recovery and the increased area fraction of twin-free grown grains.Consequently,an increase in the annealing temperature results in a gradual microstructural transition from a fully twinned grain structure to a completely twin-free grain structure.The microstructural evolution during annealing is predominantly governed by the movement of high-angle grain boundaries via a strain-induced boundary migration mechanism,and a few twin boundaries migrate above 350℃because of their lower boundary energy.The boundary migration behavior and resultant microstructural evolution are discussed in detail based on the variations in boundary mobility and driving force for boundary migration with annealing temperature.

EQUILIBRIUM POTENTIAL OF DUST GRAINS IN COMETARY PLASMA ENVIRONMENTS

The equilibrium potential of fluffy dust grains in plasma are calculated for comet P/Halley and comet P/G-Z. It is found that the dust equilibrium potential linearly correlates with the logarithm of electron density. We propose this relationship can also be applied to comet Hale-Bopp.

Field Evaluation of Growth and Yield of Two Local Rice Varieties (Tox-728-1 and Madjitolngar) in Response to Indogenous Mycorrhizal Inoculation in South-Chad

This study was carried out to find out how dependent are two local rice varieties (Magitolngar and Tox-728-1) to inoculation with selected endogenous arbuscular mycorrhizal fungi (AMF) in a field where they were isolated. The multi-indigenous endomycorrhiza spores previously isolated and identified were the active ingredient in the production of bioinoculants used for this purpose. Spores massively multiplied from the rhizosphere of each rice variety in each of the four locally collected soils substrates were harvested to constitute 08 AMF inoculants (Kema = T1;Lama = T2;Latox = T3;Ndjatox = T4;Koloma = T5;Kolotox = T6;Ndjama = T7;Ketox = T8). These inoculants were field tested on the two rice varieties at Kelo, under a complete randomized block design, comprising 10 treatments (8 inoculants, 01 positive control = T9, 01 negative control = T10), each of which was repeated thrice. The analysis of data indicates that AMF-inoculated plants were taller, developed more tillers/plant, and produced more rice grains/panicle than non-AMF-inoculated plants for both studied rice varieties. The rice variety Madjitolngar yielded more grains (7.5 t/ha) than the Tox-728-1 variety (5.8 t/ha). Moreover, inoculants Koloma (T1), Latox (T3) and Kolotox (T6) on the one hand, Koloma (T1) and Ketox (T8) on the other hand, were best suited for the improvement of growth and yield of the rice varieties Madjitolngar and Tox-728-1 respectively, tested under field conditions at Kelo. In this study, the two rice varieties have shown a dependency to endomycorrhizal symbiosis at Kelo, and therefore, an industrial-scale production of efficient endomycorrhal inoculants is necessary to sustainably boost the productivity of this important crop in Chad.

Influence of pulse magneto-oscillation on the efficiency of grain refiner

Solidification experiments were carried out in Al-Cu （w（Cu） = 5%） alloy to investigate the influence of pulse magneto-oscillation （PMO） on the efficiency of the Al3Ti1B refining agent at high superheat. The experimental solidification results show that the degree of superheat has remarkable influence on the efficiency of the grain refiner. However, the application of PMO has the potential to reduce the influence of superheat variation on the efficiency of the grain refiner. Finally, the mechanism underlying this phenomenon is discussed by performing a numerical simulation to show the forced flow inside the melt caused by PMO.

基于属性和RBAC的混合扩展访问控制模型

针对单纯的RBAC模型在动态授权、细粒度授权等方面存在的不足,将属性与RBAC相结合,并保持RBAC以角色为中心的核心思想,提出了两者结合的混合扩展访问控制模型HARBAC。模型支持基于属性的用户—角色分配、角色—权限分配、角色激活、会话角色权限缩减和权限继承等动态访问控制功能。对模型的元素、关系、约束和规则等进行了形式化描述。通过引入权限过滤策略对会话角色的有效权限进行进一步控制,分析研究了基于属性的会话权限缩减方法。应用实例表明HARBAC模型可有效实现动态授权和细粒度授权。HARBAC模型可与传统RBAC无缝集成,并在遵循其最小特权和职责分离等安全原则的基础上,有效降低管理复杂度,支持灵活、动态、可扩展的细粒度访问控制。

铝细化剂的研究进展

分析比较了稀土、AlTiC,AlTiB三种铝细化剂各自的制作方法、性能特点,并进一步阐述了它们细化纯铝的机理和存在的问题,由此提出了一条更为有效的、利用复合细化剂进行纯铝细化的新方法。

纯铁脉冲放电超高能率热处理

采用自制的高压电容器组放电获取衰减正弦特性的脉冲电流 ,对电工纯铁DT4E进行超高能率热处理 ,平均加热速率可达 1 88× 10 6 ℃ /s ,功率密度可以达到 10 9W/m2 量级。试验结果表明 ,当电容器充电电压U0 >5 5kV时试样的晶粒明显细化 ,试样的显微硬度随U0 的增加显著提高。试样被加热至熔断时 ,获得一种由羽毛状、条状组织和块状铁素体组成的复杂组织 ,其显微硬度高达 2 16HV30。电容器脉冲放电进行超高能率热处理是细化金属晶粒尺寸、提高材料力学性能的有效方法。

基于领域驱动的MIS系统细粒度权限模型研究

权限管理是管理信息系统(MIS)中非常重要的组成部分,现有部分系统中的权限管理过于粗糙或混乱,无法实现较为完整细致的权限管理;而其它的权限管理方案理论虽好,但与当今主流的软件开发方式和框架不相符,且不具备可实现性,无法应用于实际开发的信息系统。为此本文基于领域驱动设计的思想,对传统的基于角色访问控制(RBAC)模型进行细化和改进,在此基础上构建一个基于领域驱动的MIS系统细粒度的权限模型,然后再实现该模型,以展示权限系统构建的全过程,从而给目前权限系统的开发提供一个较完善的解决方案。本文给出了权限实现的详细方法和技术。

SFCW生物雷达人体细粒度运动信号微多普勒特征增强方法研究

目的本文提出了一种基于反权重系数的综合距离累积时频变换方法,增强了步进频连续波超宽带生物雷达人体细粒度运动信号的微多普勒特征。方法基于双通道步进频连续波(SFCW)雷达系统,通过将人体运动超宽带雷达信号不同距离单元信号分别进行时频变换得到各自时间-频率谱,然后根据各自相对应合理权重沿距离轴进行累积。结果基于反权重综合距离累积时频谱效果好,信号特征明显,较远距离穿墙情况下,运动信号微多普勒特征因衰减较大而较为微弱时,本方法优势十分明显。结论此法充分利用人体运动SFCW超宽带雷达信号不同距离单元信息,在保证信号特征完整性和原始性的基础上合理有效地增强运动信号时间-频谱中的微多普勒特征。

Dynamic recrystallization behavior of 35CrMo structural steel

The dynamic recrystallization behavior of 35CrMo steel was studied with compression test in the temperature range of 1 223 1 423 K and the strain rate range of 0.01 10.00 s -1 . The initiation and evolution of dynamic recrystallization were investigated with microstructure analysis and then the critical strain ε c for dynamic recrystallization initiation, the strain for maximum softening rate ε * and the steady strain ε s were obtained to be 2.92×10 -3 Z 0.1381 , 1.60×10 -3 Z 0.178 0 and 3.26×10 -2 × Z 0.097 2 respectively by analysis of work hardening rate strain θ ε curves, where Z is the Zener Hollomon parameter. The dynamic recrystallization fraction was determined using recrystallization theory, and the effects of initial grain size, strain rate and deformated temperature on the dynamic recrystallization kinetics were investigated. The results show: X DRX =1- exp(-3.23( ε-ε cε s-ε c ) 2.28 ), the dynamic recrystallization fraction is slightly delayed due to the somewhat larger initial grain size and markedly delayed with the decrease of temperature. On the other hand, it is significantly accelerated with the increase of the strain rate. Finally, the relationships between the initiation time, ending time of dynamic recrystallization and the deformed temperature were analyzed in detail.

Phase Field Simulation for Grains Evolution of 17-4PH Steel During Cyclic Heat Treatment

A phase field model is developed to simulate the grain evolution of 17-4PH steel during cyclic heat treatment （CHT）. Our simulations successfully reproduce the grain morphologies of every CHT. In the process of every CHT, phase transformation recrystallization happens. The recrystallized grains appear mainly on the original grain boundaries. The average grain size of 13.2 μm obtained by 1040 ℃×1 h solution treatment for this experimental steel can be refined to 2.2 μm after five CHT＇s. Furthermore, the effects of phenomenological parameters in our model are discussed.

Determining the impact of rectangular grain aspect ratio on tortuosity–porosity correlations of two-dimensional stochastically generated porous media

Tortuosity is an important parameter for char- acterizing transport properties within porous materials and is of interest in a broad range of fields, such as energy storage and conversion materials. One of the parameters that impacts the tortuosity value is the geometry of the solid phase which, in this study, is considered as stochas- tically-placed rectangular particles. Through lattice Boltz- mann modelling （LBM）, we determined the impact of particle aspect ratio on the intrinsic tortuosity-porosity relationships of two-dimensional porous media composed of rectangular particles. These relationships were isolated for materials with grain （particle） aspect ratios of e { 1, 2, 3 } and porosities from [0.55 - 0.95]. We determined that a minimum of 6, 8 and 10 stochastic simulations, respec- tively, were required to calculate these average tortuosity values in laminar flow （Re 〈〈 1）. This novel application of the LBM to study the effects of porosity and aspect ratio of rectangular grains on tortuosity can be used in the tailoring of materials for clean energy.

Influence of pulsed magneto-oscillation on microstructure and mechanical property of rectangular 65Mn steel ingot

The pulsed magneto-oscillation （PMO） technique has the potential to be applied in the production of heavy steel ingot. In order to confirm it and achieve more insights, the solidification of rectangular 65Mn steel ingot with the size of 220 mm×220 mm × 1000 mm was investigated under the impact of PMO. Experimental results present that PMO treatment can remarkably refine the solidified microstructure of 65Mn steel ingot in comparison with the reference ingot without PMO. The application of PMO not only significantly reduces the grain size, but also promotes the morphology transition of equiaxed grains from well-developed dendritic structures to globular structures. And the resulted globular morphology is mainly due to the fact that the PMO-induced forced flow enhances the stability of crystal growth. As a consequence, the average tensile strength of as-cast samples is enhanced from 643.4 to 762.9 MPa under the application of PMO.