Strontium ferrite powders prepared from oily cold rolling mill sludge by solid-state reaction method

Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.

Cold-state Experimental Study on Flow Characteristics of Multi-nozzle in Natural Gas Reburning Burner

Based on the prototypes of a 130 t/h boiler, constant proportional cold-state test bench is established, flow characteristics of multi-nozzle in natural gas reburning burner and its influence on the covering effect for the upflow in the furnace are researched. Numerical simulations of this process are also made with standard ?turbulence model. The results show that air flow fullness in furnace is better in the case of the reburning zone with 8 nozzles compared to 4 nozzles and also coverage effect of the reburning flow for the updraft gas in the furnace is better. In the condition each nozzle airflow velocity is constant, the effect of reburning flow on coverage of up-secondary air is best when the incident angle for four corners is 14.17?, while Center of the furnace wall is 84.57. And while the best incident angle is invariable, the effect of reburning flow on coverage of up-secondary air is best when the speed of reburning gas in the corners of furnace is 51 m/s, the same to the center of the furnace wall’s.

State Preparation in a Cold Atom Clock by Optical Pumping

We implement optical pumping to prepare cold atoms in our prototype of the ST Rb space cold atom clock, which operates in the one-way mode. Several modifications are made on our previous physical and optical system. The effective atomic signal in the top detection zone is increased to 2.5 times with 87% pumping efficiency. The temperature of the cold atom cloud is increased by 1.4 μK. We study the dependences of the effective signal gain and pumping efficiency on the pumping laser intensity and detuning. The effects of σ transition are discussed. This technique may be used in the future space cold atom clocks.

Generation of Schrdinger cat state of a single trapped cold ion

The fidelity of the generated Schrodinger Cat state （SCS） of a single trapped ion in the Lamb-Dicke approximation is discussed. The results show that the fidelity significantly decreases with the values of Lamb-Dicke parameter η and coherent state amplitude α increasing. For η= 0.20 and α = 3, the typical values of experimental parameters, the fidelity is rather low （3070）. A scheme for generating the SCS is proposed without making the Lamb-Dike approximation in laser-ion interaction, and the fidelity of the generated SCS is about 99% for the typical values of experimental Lamb- Dicke parameters.

冷热态对燃气轮机起动性能的影响

以燃气轮机整机起动试验数据为基础,定量分析燃气轮机冷热态对起动性能,包括整机点火成功转速、起动过程三个阶段时间、升转速率、压气机压比及动力涡轮出口温度的影响,初步探讨了影响机理。

冷态钢渣水化活性激发研究现状及展望

冷态钢渣作为炼钢副产物,我国每年钢渣产生量超过1亿吨,截止2022年我国有超过0.7亿吨钢渣未得到有效利用。钢渣堆存不仅占用大量土地,而且对生态环境造成了严重威胁。钢渣的化学成分和矿相组成与水泥熟料相近,通过对其活性激发处理能够用作胶凝材料。本文分析了冷态钢渣的特性,综述了国内外关于陈化激发、物理激发、化学激发、热激发和微生物激发冷态钢渣的研究现状,并对冷态钢渣水化活性激发技术的发展进行了展望。

基于水热耦合的寒区隧道仰坡稳定性研究

【目的】研究我国西北部寒冷地区的隧道仰坡稳定性及其季节温度效应的变化规律。【方法】建立寒区隧道仰坡的水热全耦合数学模型,以冻融环境变化为模拟分析基础,对其水热环境和稳定性进行数值模拟计算。【结果】结果表明,寒区隧道仰坡稳定性与土体冻融状态相关;临空面土体受环境温度影响较为明显,而内侧土温变化不显著。【结论】当温度降低,土体冻结层厚度增加时,仰坡稳定性表现较好;气温回暖季节冻融层融化,仰坡破坏滑移面几乎与坡面平行并向上延伸,极易发生滑塌灾害。

电气安全的系统性梳理与分析

电气安全在现代建筑中具有举足轻重的地位。为确保电气安全,需严格遵守相关安全规程和标准。文章旨在对电气安全进行系统性的梳理与分析,以提升电气系统在现代建筑中的安全性能,降低电气事故的发生率。对安全故障进行了分析,从降低接触电压、谐波电流、电气装置的电击防护、爆炸危险环境下的安全事项等方面进行了阐述,对整个建筑电气安全进行了系统的梳理和分析。

以期刊作为方法:美国的中国学学术史变迁

中国学期刊是展示美国中国学领域科研成果的重要载体之一,为美国和全球的区域研究提供了重要的交流平台和思想资源。美国中国学期刊的发展反映了中美关系的冷暖亲疏,大致分为三个阶段:冷战前后的曲折起步;中美建交前后的繁荣发展;全球化时代的深化拓展。为了更好推进这一领域的研究,可以从系统论、谱系论、关系论、比较论四个方面寻找解决办法。以中国学期刊作为方法,考察其不同历史阶段所呈现的创刊理念、发展路径、学者活动以及学术影响,可以透视期刊视野中的中国学历史面貌与演进过程,了解美国文化软实力的建构方式,加强中美之间的文明互鉴与交流。

Microstructure and mechanical properties of AZ31B magnesium alloy prepared by solid-state recycling process from chips

AZ31B magnesium alloy chips were recycled by three solid-state recycling processes including cold-pressing,hot-pressing followed by hot extrusion and double extrusion.Microstructure and mechanical properties of the recycled specimens and reference specimens were compared.For the recycled specimen by cold-pressing,the grains are refined to a large extent during hot extrusion due to the presence of twins and high density dislocation.The recycled specimens by hot-pressing and double extrusion do not exhibit finer grain than that the recycled specimen by cold-pressing.Consequently,higher ultimate tensile strength of the recycled specimen by hot-pressing and double extrusion is not achieved.For hot pressing process,more compact billet lowers the porosity in recycled material,so elongation to failure of the recycled specimen increases.The recycled specimen fabricated by double extrusion process shows slightly higher elongation than the reference specimen.The second extrusion makes the oxides further crush and distribute more dispersedly,and minimizes porosity,which is responsible for the improved ductility.

Six-Fold Degenerate Dark States in a Four-Level Atomic System

With all driving fields on Raman resonance, a tripod-type atomic system quickly evolves into a dark state decoupled from the lossy excited level. The dark state depends strongly on field Rabi frequencies, spontaneous decay rates, and the initial atomic population in a complicated way. Analytical results reveal that it is a sixfold degenerate dark state with its three components superposed both coherently and incoherently due to population redistribution from spontaneous emission.

废旧沥青路面绿色高值化冷态再生循环利用关键技术及示范应用

围绕废旧沥青路面绿色高值化再生利用中“新旧沥青之间混溶难”、“残余水对性能牵制强”和“施工质量变异性大”等技术难题,在国内外率先将“烹饪废油处治”和“废旧沥青路面材料再生”结合,发明了沥青质沉淀干扰技术,研发了生物油基系列再生新材料,实现了老化沥青冷态活化再生技术的“促溶升级”;研发了确定残留含水率的试验方法,提出了旧料预润技术,建立了基于性能平衡的设计方法,实现了冷态活化沥青再生技术的“减水增效”;建立了再生材料多指标分级数据库,构建了生产施工质量控制体系,实现了冷态活化沥青再生技术的全流程“控变提质”。“产学研用”以废治废形成了具有自主知识产权的废旧沥青路面绿色高值化冷态再生循环利用关键技术,推动了传统再生沥青路面工程的技术升级,实现了全产业链技术应用和示范,促进了交通运输行业绿色、循环、低碳发展,取得了显著的经济和社会效益。

Model for Interaction Between Photon and Cold Atom in QED Cavity

A model has been established for the interaction between a single-mode optical field and a 2-energy-level cold atom with exact analytic solutions given. The processes of momentum and energy exchanges between the optical field and the cold atom due to the interaction between them are discussed in detail, and a formula has been given for the variation of momentum and energy exchange volumes with time t in dress state while both the effects of photon recoil and Doppler effect are taken into consideration.

Chiral p-wave pairing of ultracold fermionic atoms due to a quadratic band touching

We study the superfuild ground state of ultracold fermions in optical lattices with a quadratic band touching. Examples are a checkerboard lattice around half filling and a kagome lattice above one third filling. Instead of pairing between spin states, here we focus on pairing interactions between different orbital states. We find that our systems have only odd-parity （orbital） pairing instability while the singlet （orbital） pairing instability vanishes thanks to the quadratic band touching. In the mean field level, the ground state is found to be a chiral p-wave pairing superfluid （mixed with finite f-wave pairing order-parameters） which supports Majorana fermions.

Simulation of global ocean acidification and chemical habitats of shallow-and cold-water coral reefs

Using the UVic Earth System Model,this study simulated the change of seawater chemistry and analyzed the chemical habitat surrounding shallow-and cold-water coral reefs from the year 1800 to 2300 employing RCP2.6,RCP4.5,RCP6.0,and RCP8.5 scenarios.The model results showed that the global ocean will continue to absorb atmospheric CO2.Global mean surface ocean temperature will rise 1.1e2.8 K at the end of the 21st century across RCP scenarios.Meanwhile,the global mean surface ocean p H will drop 0.14e0.42 and the ocean surface mean concentration of carbonate will decrease 20%e51%across the RCP scenarios.The saturated state of sea water with respect to calcite carbonate minerals(U)will decrease rapidly.During the pre-industrial period,99%of the shallow-water coral reefs were surrounded by seawater with U>3.5 and 87%of the deep-sea coral reefs were surrounded by seawater with aragonite supersaturation.Within the 21st century,except for the high mitigation scenario of RCP2.6,almost none shallow-water coral reefs will be surrounded by seawater with U>3.5.Under the intensive emission scenario of RCP8.5,by the year 2100,the aragonite saturation horizon will rise to 308 m under the sea surface from 1138 m at the preindustrial period,thus 73%of the cold-water coral reefs will be surrounded by seawater with aragonite undersaturation.By the year 2300,only5%of the cold-water coral reefs will be surrounded by seawater with aragonite supersaturation.

涡扇发动机装机状态自然低温试验

为完成涡扇发动机状态鉴定,在北方场站开展了发动机装机状态下的自然环境低温试验。通过地面试验完成了自然低温试验环境的量化分析,研究了不同气源起动模式、不同使用方法对装机状态自然低温条件下发动机起动性能的影响,分析了发动机样本量对试验鉴定结果的影响。结果表明:APU供气是低温冷浸透起动的首选起动方式;冷运转可以有效改善发动机低温起动性能,使相对起动时间缩短0.125~0.250;增加发动机样本量可以获得更加科学的鉴定结果,在低温起动过程中,发动机可能出现失速等不稳定现象,甚至造成起动失败。开展了飞行试验,研究了空中低温环境对发动机工作参数及加减速特性的影响。结果表明:在相同高度和速度下发动机加速时间随进气温度的降低而延长,当空中进气温度相差约30℃时,加速时间延长最多约为18%;减速时间随进气温度的变化不大。

冷喷涂固态增材制造沉积体形貌控制数值模拟的研究进展与展望

冷喷涂固态增材制造技术因其沉积效率高、喷涂速度快、热影响小等优点,逐渐成为各国研究热点.但由于沉积原理与目前发展较为成熟的传统激光增材制造技术具有显著不同,沉积体的形貌控制成为了限制其应用的难点.基于现有的冷喷涂条件对沉积体形貌影响的研究结果,结果表明,数值模拟成为了形貌预测与控制的主要方法.因此,综述了冷喷涂沉积体形貌预测的不同数值模拟方法,总结了各个方法的特点,最后对冷喷涂沉积体形貌模拟的现存难题及未来发展方向进行了展望.创新点:数值模拟成为了冷喷涂增材制造沉积体形貌预测的主要方法,为沉积体形貌控制和喷涂路径规划提供了理论指导.

美国FDA冷藏血小板生产替代程序指引主要内容及其启示

美国FDA新近发布了行业指引《冷藏血小板生产替代程序》,通告了有关血小板生产规定要求的例外和替代程序:在活动性出血治疗没有传统血小板可供使用及或其使用不切实际的情况下,允许采用1~6℃保存的单采血小板,其保存期为自采集之日起最长14 d,血小板生产过程验证和质量监测保留保存期末pH项目,免做血小板计数和实际血浆容量检测项目;提供了冷藏血小板制备、贴签、保存、运输、细菌污染控制、过程验证和质量监测抽样方法的具体要求和建议,讨论了冷藏血小板疗效的进一步研究需求,尤其需要在有传统血小板可供使用且其使用切合实际的情形下是否仍然支持使用冷藏血小板的研究数据。FDA建立的血液制品管理法规和质量标准的例外和替代程序的机制和实践经验颇具参考和借鉴价值。

美国、英国与战后德国的分裂(1945~1949)

二战后,美国、英国与苏联在德国问题上的分歧和矛盾越来越深。西方国家改变了原来的对德政策,由分割、限制和打击转为扶植,力图把德国纳入其势力范围,使其成为对抗苏联的重要力量。随着美苏关系的紧张,美国进一步加快了分裂德国的步伐,德国成为欧洲冷战的焦点,并由此出现了所谓第一次柏林危机,形成战后第一次美苏冷战高潮。这次危机不仅导致了德国乃至欧洲的分裂局面,也揭示出美苏冷战的基本特征。

基于“态靶辨治”理论治疗痉挛性斜颈验案

痉挛性斜颈是一种发生在颈部的局灶性肌张力障碍性疾病,临床常规治疗效果有限。本文从“态靶辨治”理论出发,认为痉挛性斜颈多属寒态,使用葛根汤加减治疗痉挛性斜颈,可取得一定疗效。葛根汤不但是寒态的调态方,也是颈项部疾病的靶方,方中葛根亦是颈项强痛之靶药,舒筋解肌时需重用至60 g,甚则可至120 g。在临床运用葛根汤时,要注意随症施量,以取得良好疗效。