Detection of the synoptic southeastward-extending Siberian cold high during 1978-2017

为了更好地研究西伯利亚地区反气旋与冷空气活动,东亚地区气温变化之间的关联,本文提出一种基于Mask R-CNN的反气旋识别方法,能够较为准确地刻画反气旋形态特征变化.使用该方法能够识别对中国冬季气温具有较大影响的东南延伸型西伯利亚冷高压(SEESCH),这种冷高压是冬季出现在西伯利亚地区的主要天气系统之一(45.7%).SEESCH携带的冷空气与下游地区温度变化呈显著负相关,52%的SEESCH伴随着华北华东地区冷空气聚集,对区域降温有显著影响.这些结果为研究SEESCH与极端寒冷事件之间的联系提供线索.

Causes of a Cold Wave Process Accompanied by Gale and a Drop in Temperature in Central Inner Mongolia

Based on the conventional high-and low-altitude and surface observation data,the weather analysis and diagnosis methods were applied to analyze the cold wave process of Ulanqab in January 2016 from the aspects of weather reality,circulation background,weather causes,and forecast test.The results show that strong cold air accumulated gradually near Lake Baikal and Central Siberia,affecting the city in a northwest path.During the cold wave process,the transverse trough moved southwards slowly at 500 hPa,and the ground cold high pressure was strong and stable.The cold air continued to move southwards,resulting in the strong cold wave and gale weather with a large impact range and long duration.The high-altitude jet at 300 hPa strengthened the cold wave pile,which was conducive to the outbreak of the cold wave.The intensity and location changes of the 500 hPa positive vorticity center,850 hPa cold advection region and 24-h ground pressure variation well showed the intensity of the cold wave process and the variation of the affected region.The influence of strong cold advection,ground positive pressure variation,and strong vertical wind shear were the main reasons for a strong drop in temperature and gale weather in this process.The test results of prediction reveal that the forecast value of the maximum temperature were relatively lower than the actual value,while the forecast of the minimum temperature was more accurate.The three warning signals were issued timely and accurately.The circulation pattern predicted by numerical models was more accurate in the early stage of the process,but there was an error in the late stage,and the forecast system moved slower than the actual situation.

Influences of Seasonal Freezing and Thawing on Soil Water-stable Aggregates in Orchard in High Cold Region,Northeast China

Soil aggregate stability,as an important indicator of soil functions,may be affected by seasonal freezing and thawing(SFT)and land use in high cold and wet regions.Therefore,comprehensive understanding the effects of SFT on aggregate stability in orchards during winter and spring is crucial to develop appropriate management strategies that can effectively alleviate the degradation of soil quality to ensure sustainable development of orchard ecosystems.To determine the mechanism of degradation in orchard soil quality,the effects of SFT on the stability of water-stable aggregates were examined in apple-pear orchards(Pyrus ussuriensis var.ovoidea)of four different ages(11,25,40,and 63 yr)on 0 to 5%slopes before freezing and after thawing from October 2015 to June 2016 in Longjing City,Yanbian Prefecture,Northeast China,involving a comparison of planted versus adjacent uncultivated lands(control).Soil samples were collected to investigate water-stable aggregate stability in three incremental soil layers(0–20,20–40 and 40–60 cm).In the same samples,iron oxide,organic matter,and clay contents of the soil were also determined.Results showed that the destructive influences of SFT on water-stable aggregates were more pronounced with the increased orchards ages,and SFT exerted severe effects on water-stable aggregates of older orchards(40 and 63 yr)than juvenile orchards.Undergoing SFT,the soil instability index and the percentage of aggregate destruction increased by mean 0.15 mm and 1.86%,the degree of aggregation decreased by mean 1.32%,and the erosion resistance weakened,which consequently led to aggregate stability decreased.In addition,soil free,amorphous,and crystalline iron oxide as well as soil organic matter and clay contents are all important factors affecting the stability of water-stable aggregates,and their changes in their contents were consistent with those in the stability of water-stable aggregates.The results of this study suggest that long-term planting fruit trees can exacerbate the damaging effects of SFT on aggregate stability and further soil erosion increases and nutrient losses in an orchard,which hider sustainable use of soil and the productivity orchards.

Preparation and performance of a cold gas dynamic sprayed high-aluminum bronze coating

By mixing preheated high-aluminum bronze powders with different amounts of Al_2O_3 powder, a low-pressure cold-sprayed coating was prepared and sprayed onto a Cr12MoV steel substrate. The hardness of the coating and the bonding strength between the coating and the substrate were tested with a HV-1000 microhardness tester and a mechanical universal testing machine. The surface microstructure, cross-section and tensile fracture surface of the coating were observed with a scanning electron microscope(SEM). Correspondingly, the influences of the preheat treatment temperature of the bronze powder and the Al_2O_3 content on the coating performance were investigated. The results indicate that the hardness of bronze powders decreased and the coating deposition rate increased after the preheating treatment of the bronze powder. The Al_2O_3 content in the mixed powders contributed to the deformation of bronze powders during the spraying process. This trend resulted in varied performance of the coating.

Current Sharing Technology in Transmission Conductors of Cold Dielectric High Temperature Superconducting Cables Using Second-generation HTS Wires

冷绝缘高温超导电缆的导电层一般设计为多层结构以满足大电流载流特性，但伴随层数的增加，超导体上的集肤效应会引起电缆输电导体各层电流分布不均匀的问题，从而造成电缆损耗增加和传输性能下降。采用基于动态惯性权重因子的粒子群优化算法，提出了电缆导体层电流层间均流优化的设计方法。应用第2代高温超导材料钇钡铜氧涂层导体，通过建立超导电缆的等效电路模型，考虑电场、磁场等约束因素，对一根1km长，110kV／3kA等级的冷绝缘高温超导电缆进行优化设计，获得了电缆本体结构参数及输电导体层和屏蔽层的电流分布。比较优化前后层电流的结果可知，优化后超导电缆各导体层电流与平均电流相比最大不平衡率小于3．5％，各屏蔽层电流达到均布，较好地实现了电缆各导体层电流均匀分布的优化目标。最后，超导模型样缆载流特性实验也验证了优化设计方法的有效性。

Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.

Strain rate and cold rolling dependence of tensile strength and ductility in high nitrogen nickel-free austenitic stainless steel

The tensile strength and ductility of a high nitrogen nickel-free austenitic stainless steel with solution and cold rolling treatment were investigated by performing tensile tests at different strain rates and at room temperature. The tensile tests demonstrated that this steel exhibits a significant strain rate and cold rolling dependence of the tensile strength and ductility.With the increase of the strain rate from 10^-4s^-1to 1 s^-1, the yield strength and ultimate tensile strength increase and the uniform elongation and total elongation decrease. The analysis of the double logarithmic stress–strain curves showed that this steel exhibits a two-stage strain hardening behavior, which can be well examined and analyzed by using the Ludwigson equation. The strain hardening exponents at low and high strain regions（n2and n1） and the transition strain（εL） decrease with increasing strain rate and the increase of cold rolling RA. Based on the analysis results of the stress–strain curves, the transmission electron microscopy characterization of the microstructure and the scanning electron microscopy observation of the deformation surfaces, the significant strain rate and cold rolling dependence of the strength and ductility of this steel were discussed and connected with the variation in the work hardening and dislocation activity with strain rate and cold rolling.

Preparation of novel Ni-Ir/γ-Al_2O_3 catalyst via high-frequency cold plasma direct reduction process

The novel Ni-Ir/γ-Al2O3 catalyst, denoted as NIA-P, was prepared by high-frequency cold plasma direct reduction method under ambient conditions without thermal treatment, and the conventional sample, denoted as NIA-CR, was prepared by impregnation, thermal calcination, and then by H2 reduction method. The effects of reduction methods on the catalysts for ammonia decomposition were studied, and they were characterized by XRD, N2 adsorption, XPS, and H2-TPD. It was found that the plasma-reduced NIA-P sample showed a better catalytic performance, over which ammonia conversion was 68.9%, at T = 450℃, P = 1 atm, and GHSV = 30, 000 h^-1. It was 31.7% higher than that of the conventional NIA-CR sample. XRD results showed that the crystallite size decreased for the sample with plasma reduction, and the dispersion of active components was improved. There were more active components on the surface of the NIA-P sample from the XPS results. This effect resulted in the higher activity for decomposition of ammonia. Meanwhile, the plasma process significantly decreased the time of preparing catalyst.

A Cold Adhesion for Self-fused Alloy Coat by High Frequency Induction

In this study, a method to prepare self-fused alloy coat, which started with a cold adhesion precoating and then induction fusing plus, is presented. It also intended to analyze the mechanism, microstructure and anitwear ability of the coat. The workpiece was precoated with Ni60 powder through an adhesion agent. The oven-dried precoat was then heated by a high frequency induction generated by 100kw power with a frequency of 250kHz. The technological parameters of the method were determined through analysis of the thermal magnetism, thermal resistivity and anti-induction mechanism. By comparing the microstrucrures and properties of the coat produced by cold adhesion, thermal spraying and laser refusing, it is concluded that: (1) One side of the workpiece should be preheated to 200℃ before induction fusion, and the range of induction frequency should be 200～250kHz. (2) The microstrucrure of the coat by cold adhesion is superior to that by thermal spraying, but the particle size range should be 0.047～0.044mm (200～320 meshes) (3) The corrosion resistance of Ni60 coat by cold adhesion is better than that by thermal spraying, and the cold adhesion is the best method to prepare the antiwear coat.

Cold Atom Cloud with High Optical Depth Measured with Large Duty Cycle

We present a cold atom system with a dark-line two-dimensional magneto-optical trap, to increase the atomic density by suppressing the atomic radiation pressure. Optical depth （OD） and duty cycle are used to evaluate the system performance. We demonstrate a 100% increase in OD with the dark line, and obtain an ultrahigh OD of 264 with 10% for the duty cycle. Also, with an efficient dark line region, the OD could maintain above i00 with duty cycle as high as 30%. The cold atomic ensemble with an ultrahigh OD with a 10%-30% duty cycle is particularly advantageous in quantum i^formation processing and communication.

Study on microstructure and properties of cold-rolled high strength steel for enameling

With its superior comprehensive properties, cold-rolled enameling steel is widely applied in many fields. However, its low yield stress greatly limits its application. This study aims to improve the yield stress of cold-rolled enameling steel under the premise of meeting formability and enameling properties by strengthening the ferrite matrix via solid strengthening of Mn. The grain size of ferrite before and after enameling,mechanical properties of annealed steel, and precipitation behavior of second-phase precipitates are obtained through studying the microstructure and properties of enameling steel at different stages. The microstructure of the steel investigated at room temperature is found to contain equiaxial ferrite and bunchy cementite particles;the ferrite grains have grown to some extent after enameling. The fine dispersed TiC particles and cementite particles contained in the annealed steel are the main factors improving the hydrogen storage capability. Finally, the result of a falling-ball impact test shows that the steel has achieved excellent adherence.

Effects of cold rolling deformation on microstructure,hardness,and creep behavior of high nitrogen austenitic stainless steel

Effects of cold rolling deformation on the microstructure, hardness, and creep behavior of high nitrogen austenitic stainless steel （HNASS） are investigated. Microstructure characterization shows that 70% cold rolling deformation results in significant refinement of the microstructure of this steel, with its average twin thickness reducing from 6.4 μm to 14 nm. Nanoindentation tests at different strain rates demonstrate that the hardness of the steel with nano-scale twins （nt-HNASS） is about 2 times as high as that of steel with micro-scale twins （mt-HNASS）. The hardness of nt-HNASS exhibits a pronounced strain rate dependence with a strain rate sensitivity （m value） of 0.0319, which is far higher than that of mt-HNASS （m = 0.0029）. nt-HNASS shows more significant load plateaus and a higher creep rate than mt-HNASS. Analysis reveals that higher hardness and larger m value of nt-HNASS arise from stronger strain hardening role, which is caused by the higher storage rate of dislocations and the interactions between dislocations and high density twins. The more significant load plateaus and higher creep rates of nt-HNASS are due to the rapid relaxation of the dislocation structures generated during loading.

Research on the design of cold rolled ultra high strength sheet steel

This study researches cold rolled ultra high strength martensitic steel processed by water quenching. It is found that both the quenching and overageing temperatures greatly influence the mechanical properties of martensitic steel. A tensile strength of 1500 MPa can be obtained from 0.2% C-1.8% Mn steel by soaking at 840℃,quenching at 700℃ and overageing at 200℃ for several minutes. The continuous cooling transformation （CCT） diagram reveals that full martensite can be obtained at a cooling rate of 100℃/s or higher; and at a cooling rate of 3 - 10℃/s,austenite barely decomposes at 700℃. For steel with 0.2% carbon and less manganese, austenite decomposition occurs before it is cooled to 700℃ at a cooling rate of 3 - 10℃/s, which leads to lower tensile strength. It is possible to reduce the manganese content of the 1500 MPa martensitic steel by increasing the quenching temperature. To increase the quenching temperature,the control of flatness during water quenching becomes a major concern.

Structural analysis and design of frost resistance function for subgrade of high-speed railway ballasted track in cold regions

According to the technical characteristics of short fixed wheelbase of a high-speed carriage, a subgrade-track integrated space mechanical response analysis model is proposed for trains under the action ofbiaxial load after the comparison of the stress distribution characteristics of the ballast track subgrade bed structures for high-speed railway under the action of uniaxial load and biaxial load. The loading threshold value （high-cycle long-term dynamic strength） under the circum- stance where the cumulative deformation of subgrade structure gradually develops and finally reaches the convergent state, and its relationship with the foundation coefficient K30 were deduced, based on the characteristics of cumulative defor- mation evolution obtained from the unit structure filling model test under the action of cyclic loading. In view of structure stability and frost resistance requirements of the railway subgrade in cold regions, technical conditions to maintain good service performance of subgrade structure of high-speed railway ballasted track are discussed and analyzed. Study results show that the additive effect manifests itself obviously for railway train bogies under the action of biaxial load than uni- axial load, which has a significant dynamic effect on the subgrade bed bottom and a slight effect on the surface layer. Thus, the adoption of a biaxial load model in the design of a high-speed railway subgrade accurately reflects the vehicle load. Pursuant to the structure design principle, the design method of the subgrade structure of high-speed railway ballasted track is proposed to meet the technical requirements such as structural strength, bearing stiffness and high-cyclic and long-term stability. Technical indicators are obtained for the variation of thickness of the surface layer of reinforced sub- grade bed in the double-layer subgrade mode along with the change of K30 at the subgrade bed bottom. The double-layer structure mode of ＂closure on the upper layer and drainage on the lower layer＂ was proposed in order to meet the water- proofing and drainage requirements of the upper layer of the subgrade bed in cold regions. A dense-framework graded gravel filler with weak water permeability at a coefficient of 10 4 cm/s is used on the upper layer and the void-framework graded gravel filler at the water permeability coefficient of 10 2 cm/s is adopted on the lower layer.

Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

In this study, the suitability of current design methods for the 0.2% proof yield strength of the corner regions for high strength cold-formed steel at normal room temperature was investigated. The current standard predictions are generally accurate for outer corner specimen but conservative for inner corner specimen. Based on the experimental results, an analytical model to predict the corner strength of high strength cold-formed steel at normal room temperature was also proposed. The comparison indicated that the proposed model predicted well the corner strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures. It is shown that the predictions obtained from the proposed model agree well with the test results. Generally the corner strength enhancement of high strength cold-formed steel decreases when the temperature increases.

Precursory atmospheric teleconnection patterns for strong Siberian High events

本文利用日本55年逐日再分析资料,发现在SH异常增强前,有三种不同的大气遥相关型前兆信号,即斯堪的纳维亚(SCA)型,西太平洋(WP)型,极地-欧亚(POL)型据此,本文将异常增强的SH分为对应的三类事件.合成结果表明,三类事件在典型环流特征和对东亚气温的影响上存在着明显的不同.具体而言,SCA类事件主要表现为在欧亚中高纬度上自西向东的波列异常,WP类事件表现为环流异常自下游太平洋/俄罗斯远东地区向西发展的特征,POL型事件的显著信号则来源于自极区向南移动的反气旋式环流异常.在对东亚地表气温的影响上,SCA类与POL类事件类似,它们均可造成大范围的低温异常.而WP类仅在我国北方和东部地区造成强度较弱的地表气温异常,但该异常的持续性特征较明显。

无痛内镜下冷切除与高频电切在结直肠息肉治疗中的应用价值

目的:探究无痛内镜下冷切除与高频电切在结直肠息肉治疗中的应用价值。方法:选择2018年1月—2021年12月在大连市第三人民医院消化科治疗的结直肠息肉患者180例,应用随机数字表法将其分为对照组(无痛内镜下高频电切)及观察组(无痛内镜下冷切除),各90例。对比两组临床指标(手术时间、术后禁食时间、排便时间)、治疗总有效率、炎症因子[C反应蛋白(CRP)、白细胞介素-1β(IL-1β)、白细胞介素-6(IL-6)]、应激指标[肾上腺素(E)、去甲肾上腺素(NE)、皮质醇(Cor)]、并发症发生率。结果:观察组手术时间、术后禁食时间、排便时间均短于对照组,差异均有统计学意义(P<0.05)。对照组治疗总有效率低于观察组,差异有统计学意义(P<0.05)。术前,两组IL-1β、IL-6、CRP水平对比,差异均无统计学意义(P>0.05);术后,两组IL-1β、IL-6、CRP水平均升高,但观察组均低于对照组,差异均有统计学意义(P<0.05)。术前,两组E、NE、Cor水平对比,差异均无统计学意义(P>0.05);术后,两组E、NE、Cor水平均升高,但观察组均低于对照组,差异均有统计学意义(P<0.05)。对照组并发症发生率高于观察组,差异有统计学意义(P<0.05)。结论:相较高频电切治疗结直肠息肉,无痛内镜下冷切除效果更佳,可促进患者恢复,减轻炎症反应、应激损伤,降低并发症,安全性较高。

嵌套加强的LQ550高强冷弯薄壁C型钢连续檩条受力性能研究

为提高LQ550级高强冷弯薄壁C型钢连续檩条的承载能力,采用在支座处嵌套的方法来加强连续檩条。对未加强和采用两种嵌套方式加强的檩条共7组试件进行三点受弯试验,得到了试件的承载性能和破坏形态,试验结果表明加强后的试件出现跨中局部屈曲和嵌套端部局部屈曲两种破坏形态。采用ABAQUS软件建立了非线性有限元模型对嵌套加强的檩条进行数值模拟,有限元分析得到的承载力和破坏形态与试验结果吻合良好,验证了有限元模型的准确性。基于验证的有限元模型,分析了两种嵌套方式和不同嵌套长度对檩条承载力的提升,且表明嵌套檩条的长度宜取为连续檩条跨度的1/5~1/4。