Isotopic dependence of the yield ratios of light fragments from different projectiles and their unified neutron skin thicknesses

The yield ratios of neutron-proton(R(n/p))and^(3)H-^(3)He(R(^(3)H∕^(3)He))with reduced rapidity from 0 to 0.5 were simulated at 50 MeV/u even-even ^(36−56)Ca+^(40)Ca,even-even ^(48−78)Ni+^(58)Ni,and ^(100−139)Sn(every third isotopes)+112 Sn for full reduced impact parameters using the isospin-dependent quantum molecular dynamics(IQMD)model.The neutron and proton density distributions and root-mean-square radii of the reaction systems were obtained using the Skyrme-Hartree-Fock model,which was used for the phase space initialization of the projectile and target in IQMD.We defined the unified neutron skin thickness asΔRnp=<r^(2)>^(1∕2) n−<r^(2)>^(1∕2)p,which was negative for neutron-deficient nuclei.The unifiedΔRnp values for nuclei with the same relative neutron excess from different isotopic chains were nearly equal,except for extreme neutron-rich isotopes,which is a type of scaling behavior.The yield ratios of the three isotopic chain-induced reactions,which depended on the reduced impact parameter and unified neutron skin thickness,were studied.The results showed that both R(n/p)and R(^(3)H∕^(3)He)decreased with a reduced impact parameter for extreme neutron-deficient isotopes;however,they increased with reduced impact parameters for extreme neutron-rich isotopes,and increased with theΔRnp of the projectiles for all reduced impact parameters.In addition,a scaling phenomenon was observed betweenΔR np and the yield ratios in peripheral colli-sions from different isotopic chain projectiles(except for extreme neutron-rich isotopes).Thus,R(n/p)and R(^(3)H∕^(3)He)from peripheral collisions were suggested as experimental probes for extracting the neutron or proton skin thicknesses of non-extreme neutron-rich nuclei from different isotopic chains.

Effect of Cooling History on Yield Ratio of Fine-grain Ferrite/Pearlite Steel

Effect of different cooling history on yield ratio of HP295 steel for welded gas cylinder was studied and the result implied that both fine microstructure and good mechanical properties can be attained by using two-stage cooling and controlling the coiling temperature. The yield ratio of HP295 steel sheet was reduced to less than 0.8 by twostage cooling process. The pass percent of yield ratio was enhanced from less than 90% to 100%. The mechanical properties satisfied the criteria of GB6653-1994.

Determining role of heterogeneous microstructure in lowering yield ratio and enhancing impact toughness in high-strength low-alloy steel

Here we present a novel approach of intercritical heat treatment for microstructure tailoring,in which intercritical annealing is introduced between conventional quenching and tempering.This induced a heterogeneous microstructure consisting of soft intercritical ferrite and hard tempered martensite,resulting in a low yield ratio(YR)and high impact toughness in a high-strength low-alloy steel.The initial yielding and subsequent work hardening behavior of the steel during tensile deformation were modified by the presence of soft intercritical ferrite after intercritical annealing,in comparison to the steel with full martensitic microstructure.The increase in YR was related to the reduction in hardness difference between the soft and hard phases due to the precipitation of nano-carbides and the recovery of dislocations during tempering.The excellent low-temperature toughness was ascribed not only to the decrease in probability of microcrack initiation for the reduction of hardness difference between two phases,but also to the increase in resistance of microcrack propagation caused by the high density of high angle grain boundaries.

Yield ratios and directed flows of light particles from proton-rich nuclei-induced collisions

The neutron-to-proton and3 H-to-3 He yield ratios, and the directed flows of particles dependent on a reduced rapidity, the transverse momentum per nucleon,and a reduced impact parameter are investigated for ^(28)S+^(28)Si and ^(32)S+^(28)Si systems at 50 and 400 MeV/u using an isospin-dependent quantum molecular dynamics model.The results show that these yield ratios of projectile-like fragments are approximately equal to the constituent neutron-to-proton ratio of the projectile. There are clear differences of the directed flows for isospin-related fragments neutron and proton,~3H and ~3He from ^(28)S+^(28)Si collisions.The differences in directed flows for neutrons and protons and ~3H–~3He from a proton-rich nucleus ^(28)S- induced collisions are noticeably larger than those from a stable nucleus ^(32)S- induced reactions under medium impact parameters. Thus, the yield ratios and differences in directed flows for the neutrons and protons and ~3H–~3He under medium impact parameters are proposed as possible observable items for studying isospin physics.

Impact parameter dependence of the yield ratios of light particles as a probe of neutron skin

The yield ratios of neutron/proton(R(n/p)) and ~3H=~3He(R(t/~3He)) with reduced rapidity from 0 to 0.5 are investigated for 50 MeV/u ^(42;44;46;48;50;52;54;56)Ca+^(40)Ca.This was conducted at whole reduced impact parameters using the isospin-dependent quantum-molecular-dynamics model in which the initial neutron and proton densities are sampled within the Skyrme–Hartree–Fock model, using which the neutron skin thickness(△R_(np)) is determined for different neutron-rich Ca isotopes. The results show that both R(n/p) and R(t/~3He) have strong linear correlations with △R_(np) of different Ca isotopic projectiles from five different centralities. It is suggested that R(n/p) and R(t/~3He), from the same centrality, could be treated as possible experimental observables to extract the neutron skin or halo thickness for neutron-rich isotopic nuclei,including the nuclei near the neutron drip line.

A nuclear density probe:isobaric yield ratio difference

We report our recent progress on the nuclear symmetry energy probe,which is called the isobaric yield ratio difference(IBD),and its application in neutron density determination in experiments.The results obtained by the IBD,from which the isobaric yields in the measured 140 A MeV ^(40.48)Ca + ~9Be and ^(58.64)Ni + ~9Be reactions,and the calculated 80 A MeV ^(38-52)Ca +^(12)C reactions by using a modified statistical abrasion-ablation model,show the sensitivity of the IBD to the density differences between reactions.

Effects of Coiling Temperature on Strength,Yield Ratio and Precipitation Behaviors of Hot Rolled High Strength Microalloyed Steel for Cold Forming

Various hot rolling schedules were applied to a Nb,V,Ti contained HSLA steel.Coiling temperature had crucial effects on not only yield strength,but also yield ratio and precipitation behavior.600Mpa yield strength is achieved when coiled at 450℃,which is 100Mpa higher than those coiled at 570℃.However,the low coiling temperature had adverse effect to increase yield ratio,which increased from 0.78 to 0.88 as coiling temperature dropped from 570℃ to 450℃.High resolution SEM analysis shows that sizes of Nb,V,Ti precipitates are affected by coiling temperature.Coarse (Nb,Ti)(C,N) precipitates up to 5μm are observed at higher coiling temperature and to decrease tensile strength,where high coiling temperature corresponds to low cooling rate.With strong cooling and coiling capacity of Shasteel’s 1450mm width hot rolling mill,these results indicate that strength and formability of the steel can be balanced when coiling temperature has been optimized.Alloying and microalloying costs can be reduced by efficiently utilizing the capacity of rolling mill.Alumina inclusions are found to act as nucleus for Nb,V,Ti precipitates,contributing to coarsening of precipitates.

Effects of Rolling Processes on Yield Ratio and Formability of Hot Rolled Gas Cylinder Steel

Deep drawing properties of hot rolled gas cylinder steel was investigated by using HP295 steel in terms of microstructure, texture, yield ratio, plastic strain ratio （r value） and plastic anisotropy （Ar）. The grains in the hot strip were largely equiaxed, and the texture was weak, containing a- and ？＇fibre. Reheating temperature, finish roll ing temperature and cooling rate after rolling influenced the ferrite-pearlite band formation significantly, and the yield ratio increased steeply with decreasing coiling temperature below 630 ~C. The anisotropy is relatively high due to re- tained severe ferrite-pearlite band. A mechanism of the band formation due to manganese segregation is elaborated and confirmed validly, from which the measures to avoid the band formation are worked out. Rolling parameters have been optimized by the measures, and industrial production of the gas cylinder steel has been made possible with much improved r-and △r-values, while meeting other specifications.

Yield ratios and directed flows of light fragments from reactions induced by neutron-rich nuclei at intermediate energy

The yield ratios of neutron/proton and ^3H/^3He and the directed flow per nucleon for these projectile-like fragments at large impact parameters are studied for ^50Ca ＋ ^40Ca and ^50Cr ＋ ^40Ca for comparison at 50 MeV/u using the isospin-dependent quantum molecular dynamics（IQMD model.It is found that the yield ratios and the directed flows per nucleon are different for reactions induced by the neutron-rich nucleus ^50Ca and the stable isobaric nucleus ^50Cr,and depend on the hardness of the EOS.The ratios of neutron/proton and ^3H/^3He and the difference of directed flow per nucleon of neutron-proton are suggested to be possible observables to investigate the isospin effects.

Probing Temperature from Intermediate Mass Fragment by Isobaric Yield Ratio in Heavy-Ion Collisions

A probe to extract the temperature(T_(iyr)) from intermediate-mass fragment has been proposed using the isobaric yield ratio(IYR) difference based on the modified Fisher model.By analyzing the isobaric cross section in the measured 140 A MeV^(40,48)Ca+~9Be reactions,the Tiyr can well fit the IYR difference for the large mass fragments.Because of the fragments are produced in different colliding regions,it is also suggested to select the fragments according to different mechanisms when using TIYR.

Responses of Seed Yield and Economic Benefit of Winter Oilseed Rape(Brassica napus L.) to Different NPK Ratio and Dose

Field experiments were conducted during 2008-2010 to investigate the effects of NPK fertilization on seed yield and economic benefit of a new hybrid cultivar of winter oilseed rape(Brassica napus L.)- Xiangzayou763,and to determine the optimum NPK ratio and dose in Hunan,China.The results showed that NPK ratio(1:0.50:0.50) with 180 kg/hm2 N,90 kg/hm^2 P_2O_5 and 90 kg/hm^2 K_2O was the optimum combination for the highest seed yield(2 231.13 kg/hm2) and economic benefit(9 816.97 Yuan/hm^2),of which 1 641.23 Yuan/hm^2 being set for fertilizer investment(VCR=4.11).Besides,the effects of N,P and K fertilizers on seed yield and oil production of winter oilseed rape were not identical.N had the greatest effect on plant growth of winter oilseed rape,followed by P and K.Total leaf number,green leaf number,leaf length and width,rhizome diameter,branch number,dry weight per plant and other agronomic characters in high N treatments were higher than those in low N treatments.By correlation and path analysis of yield components,the contribution rate to seed yield was found:effective silique number per plant>seed number per silique>1 000-seed weight.

Influence of yield-to-tensile strength ratio(Y/T) on failure assessment of defect-free and corroded X70 steel pipeline

The effect of yield-to-tensile strength ratio(Y/T) on failure pressure of X70 pipeline without and with corrosion defects was investigated.The stress-strain response of materials was characterized by a power-law hardening curve.Two formulas to estimate the strain hardening exponent n for a special Y/T were obtained by least squared regression method and the influence of Y/T on n was analyzed.As an application of n-Y/T expression,the analytical solutions of burst pressure for X70 pipeline without and with corrosion defects were also obtained.The results indicate that the burst pressure of defect-free X70 pipe without corrosion defects is a function of the Y/T,pipe geometry t0/D0 and engineering tensile strength,and increases as Y/T or t0/D0 increases; whilst the burst pressure of corroded X70 pipe decreases with the increase of defect depths,d/t.Comparisons indicate that the present analytical solutions closely match available experimental and numerical data.

Study on the Relationship of Seedling Density and Line Spacing to Leaf-stem Ratio, DW/FW Ratio and Grass Yield of Forage Sweet Sorghum

[ Objectives ] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum （ Sorghum blcolor （ L. ） Moench） and explore its high-yield cultivation techniques. [ Methods] Effects of such two influencing factors as line spacing and seedling density on the leaf-stem ratio, DW/FW ratio and grass yield of forage sweet sorghum were analyzed by using split-plot experiment design experiment method and LSD method of IBM. SPSS. Statis- tics. v22 stati, stics software. [ Results ~ Seedling density and line spacing had no obvious effect on the leaf-stem ratio and DW/FW ratio of forage sweet sorghum but had obvious influences on the grass yield. Moreover, the optimal combination of seedling density and line spacing for high yield of forage sweet sorghum was A2 B4, that is, seedling density was 225 000 plants/hm2, and line spacing was 40 cm. [ Conclusions] The results provided a theoretical basis and technical support for high-yield cultivation techniques of forage sweet sorghum.

Effect of Shoot-Fruit Ratio on Grape Yield,Quality and Storage Nutrient

With the grape variety ＂Summer Black＂ as the test material, the effects of different shoot-fruit ratios on grape yield, fruit quality and grapevine storage nutrient were investigated for 2 consecutive years, so as to determine the optimized load for Summer Black grapes in Shandong. The results showed that the grapes with shoot-fruit ratio of 1∶ 1 had the highest soluble solid content, vitamin C content and grapevine storage nutrient. Based on the comprehensive analysis, the shoot-fruit ratio of 1∶ 1 was the optimized load for Summer Black grapes in Tai an of Shandong Province, and the yield was 1 179.37-1 288.63 kg per 667 m^2.

Effects of Ratio of Row Spacing to Intrarow Spacing on Yield and Nitrogen Accumulation and Utilization of Early and Late Rice

[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17’and late rice‘Ganxin 688’and‘Wufengyou T025’as materials,the effects of RS/IS on yield,nitrogen accumulation and utilization were studied in the same planting density of31.20×104hills/hm2.[Results]The results showed that yield of early rice was higher in RS/IS2.8(30.0 cm×10.7 cm)and RS/IS2.0(25.0 cm×12.8 cm)treatment,and lower in RS/IS5.0(40.0 cm×8.0 cm)and RS/IS1.3(20.0 cm×16.0 cm)treatment,while late rice were higher in RS/IS5.0and RS/IS2.0treatment,and lower in RS/IS2.8and RS/IS1.3treatment.Total nitrogen accumulation and apparent utilization ratio of nitrogen of early rice were higher in RS/IS2.0treatment and lower in RS/IS5.0treatment,while,for late rice were higher in RS/IS2.8treatment and lower in RS/IS5.0treatment.Nitrogen requirement for 100 kg grain production of early rice was higher in RS/IS1.3treatment and lower in RS/IS2.0treatment,while,for late rice were higher in RS/IS2.8treatment,lower in RS/IS5.0treatment.[Conclusion]In sum,4 varieties of early and late rice obtained higher yield in 25.0 cm×12.8 cm and lower yield in 20.0 cm×16.0 cm,and total nitrogen accumulation,nitrogen requirement for 100 kg grain production and apparent utilization ratio of nitrogen were all lower in 40.0 cm×8.0 cm.

玉米大豆带状复合种植模式研究

为探讨适宜云南玉米大豆带状复合种植模式,2022年选用玉米云瑞668和大豆台湾75-3为试验材料进行大田试验,研究玉米大豆带状复合种植不同模式下不同处理对玉米和大豆农艺性状和产量构成因素的影响。结果表明,可机械化作业的田块应优先选用玉米大豆行比4∶4和4∶3模式,山区或半山区推广玉米大豆行比2∶2模式。该研究为玉米、大豆带状复合种植在云南省保山市及气候类似地区推广提供了理论依据。

两相区淬火温度对Ni-Cr-Mo-V系高强船体钢组织及性能的影响

为改善高强船体钢高屈强比、回火区间窄的问题,研究了两相区二次淬火温度对Ni-Cr-Mo-V系高强船体钢组织及性能的影响。通过改变二次淬火温度,研究实验钢冲击拉伸性能和显微组织的变化规律,并通过OM、TEM、XRD衍射等方法进行表征。结果表明,在淬火温度区间内,材料的性能表现出两种变化趋势。当淬火温度在640~700℃时,实验钢的强度随着二次淬火温度的上升而增加,而韧性下降。在该淬火温度范围内,实验钢的机械性能由铁素体+马氏体的双相组织和逆转变奥氏体的含量决定。随着二次淬火温度的上升,双相组织中铁素体的比例从40%降至10%,逆转变奥氏体的含量从11%下降至1%。当二次淬火温度从700℃增加到780℃时,实验钢的强度和韧性变化不明显,原因是二次淬火的温度已经超过了A3温度,实验钢组织转变为单一的马氏体组织,奥氏体晶粒尺寸变化不大(7.3~8.5μm)。综上,在680℃下进行两相区二次淬火可以获得最佳的强度和韧性匹配。

不同基质配比对大叶芹生长和产量的影响

选用田园土、松针、椰糠、炉渣按照不同比例配置6种复合基质,以田园土为CK,通过测定基质理化性状、出苗率、幼苗生长指标、成苗的品质与产量,筛选出大叶芹人工栽培的最优基质。结果表明,S3(田园土:松针:炉渣=1:1:1)处理的大叶芹发芽率可达100%,总干物质量为0.20 g,壮苗指数为1.20。与CK相比,株高提高了21.8%,茎粗提高了26.1%,可溶性糖含量提高了20.5%,纤维素含量降低了33.9%,总黄酮含量提高了79.7%,总酚含量提高了28.5%,产量提高了14.6%。综合产量及品质指标,得出S3为较理想的人工栽培基质配方。

等带宽间作模式下不同玉米花生行比对花生光合特性和系统产量的影响

【目的】明确相同带宽条件下不同玉米花生种植行比对花生光合特性和系统产量的影响,为构建适宜行比的玉米花生带状间作模式提供理论参考和技术支持。【方法】以玉米花生带状间作系统为对象,设置玉米单作,花生单作,玉米花生间作(3.6 m的总带宽,行比分别为2∶6、4∶4、6∶2),研究不同行比对间作花生干物质积累、叶面积指数、叶片光合参数、产量构成和玉米花生系统产量的影响。【结果】3种间作模式的干物质量和叶面积指数均小于单作,其中2∶6种植模式在花生生育后期的叶面积指数较4∶4和6∶2分别提高30.07%和44.19%,等带宽间作体系下相对较少的玉米行比可以增加间作花生的叶绿素含量和光合速率,保持花生叶片较高的光合能力,从而获得产量优势。间作显著降低了玉米的穗数、穗粒数和百粒重以及花生的单株饱果数和百果重,系统产量以2行玉米6行花生的种植模式最高,为13749.9 kg/hm^(2),3种间作模式的土地当量比均大于1,且综合产量均显著高于单作玉米和单作花生。【结论】在玉米花生等带宽间作模式下,花生行比的增加缓解了玉米的荫蔽效应,改善了花生的光合能力,同时提高土地利用率,实现稳粮增油、均衡生产。

有机无机肥配施对江苏滨海盐碱土农田生产力和碳库的影响

[目的]有机肥施用是江苏滨海轻度盐碱地主要的改土提质技术,本试验通过研究在有机替代模式下夏玉米种植系统农田生产力和土壤碳库的变化特征,探索在粉垄耕作模式下有机肥还田同氮肥减量的最佳比例。[方法]按照等氮量投入原则,以当地氮肥施用(CK)为对照,设置25%有机肥+75%氮肥(CT25)、50%有机肥+50%氮肥(CT50)、75%有机肥+25%氮肥(CT75)、有机肥全量替代氮肥(CT100)处理,开展粉垄耕作模式下不同比例有机肥替代氮肥玉米种植田间试验,对玉米农田生产力和土壤碳库指标进行测定。[结果]与氮肥全量施用相比,有机肥替代化肥比例在25%~50%时,玉米籽粒产量可增加8.74%~11.21%,其中CT25处理的玉米光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))、胞间CO_(2)浓度(C_(i))显著增加,土壤全氮、全磷、全钾、碱解氮、速效磷、速效钾含量均较单施氮肥显著增加,有机替代比例超过50%以上时玉米产量和土壤养分较纯施氮肥无显著变化。相较于纯施氮肥,有机肥替代比例在25%~75%时土壤碳储量提升9.47%~14.61%,这主要依赖于土壤有机碳含量和容重的显著增加。土壤有机碳含量和玉米产量呈显著的正相关关系。[结论]粉垄耕作模式条件下,有机肥替代氮肥在25%~50%可以显著改善土壤理化性质,增加土壤碳储量,提升农田生产力,可作为江苏滨海旱作玉米种植推荐施肥技术。