Electronically Controlling the System of Preheating Intake Air by Flame for Diesel Engine Cold-Start

In order to improve the cold start performance of heavy duty diesel engine, electronically controlling the preheating of intake air by flame was researched. According to simulation and thermodynamic analysis about the partial working processes of the diesel engine, the amount of heat energy, enough to make the fuel self ignite at the end of compression process at different temperatures of coolant and intake air, was calculated. Several HY20 preheating plugs were used to heat up the intake air. Meanwhile, an electronic control system based on 8 bit micro controller unit (MCS 8031) was designed to automatically control the process of heating intake air. According to the various temperatures of coolant and ambient air, one plug or two plugs can automatically be selected to heat intake air. The demo experiment validated that the total system could operate successfully and achieve the scheduled function.

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.

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.

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.

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.

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。

煤矿机械用690MPa级高强钢不预热焊接技术

Q690是煤矿机械装备向着高强和大规格发展所必需的高性能钢铁材料,为解决高强钢需要焊前预热以防止产生冷裂纹的技术难题,也为解决焊前预热带来的生产效率低、成本高的行业困难,宝钢研制生产了煤矿机械用不预热焊接钢Q690HP,采用超低碳当量设计,使其具备了优良的焊接性、实现不预热焊接。通过斜Y型坡口焊接裂纹试验,评价了特定温度环境下冷裂纹敏感性与不预热焊接工艺可行性;通过不预热焊接接头试验,系统评价不预热焊接条件下接头使用性能,得到Q690HP不预热焊接技术匹配的焊丝和焊接工艺参数。结果表明:环境温度5℃不预热条件下,采用不同焊丝焊接的小铁研试样焊缝均无裂纹,Q690HP钢板具有优异的抗裂纹敏感性;环境温度5℃不预热条件下,线能量为7~12 kJ/cm且层间温度控制在100~150℃时,选用2#和5#焊丝进行不预热气保焊焊接,得到的焊接接头性能满足力学性能要求。

低温环境下柴油机冷起动性能试验研究

为改善柴油机冷起动性能,对某排量为2.5 L、采用进气加热器预热的柴油机开展环境温度为-30℃极寒条件下的冷起动试验,研究压缩比、节气门开度、预热方式、控制策略等对柴油机冷起动性能的影响。试验结果表明:压缩比为17.0,采用进气加热器时,柴油机加热时间较长,功率消耗大,无法正常起动;增大压缩比和节气门开度,能够提高压缩终了时缸内混合气的压力和温度,改善低温时柴油机的冷起动性能,但效果不佳;采用预热塞预热,柴油机起动迅速,起动时间为3.95 s,可有效提高柴油机冷起动性能;预热塞和燃油油束的相对距离通常设置为0.4~2.0 mm。

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。

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。

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.

Validation for equation of state in wide regime:Copper as prototype

In this paper we introduce the wide regime equation of state(WEOS)developed in Institute of Applied Physics and Computational Mathematics(IAPCM).A semi-empirical model of the WEOS is given by a thermodynamically complete potential of the Helmholtz free energy which combines several theoretical models and has some adjustable parameters calibrated via some experimental and theoretical data.The validation methods of the equation of state in wide regime are presented using copper as a prototype.The results of the WEOS are well consistent with the available theoretical and experimental data,including ab initio cold curve under compression,isotherm,Hugoniot,off-Hugoniot and sound velocity data.It enhances our confidence in the accuracy of the WEOS,which is very important for the validation and verification of equation of state in high temperature and pressure technology.

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.

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.

Compound control for speed and tension multivariable coupling system of reversible cold strip mill

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.

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.

Why the Cold War Will Never Return to World Politics

Every serious confrontation between the United States and Russia evokes new cold war debates.The Cold War found its true meaning because it had achieved to create its own momentum within time.This question is a great test in terms of measuring the level that today’s international relations has reached:Is cold war still relevant in a global politics?The answer to be given to this question depends on whether any cold war can be maintained against all the pluralistic tendencies of international relations.It will be a negative one because the dynamics unleashed by globalization are likely to marginalize new cold war regardless of the will to wage and sustain it.For,beyond the will to wage and sustain it,the concept of cold war is a technical issue that can only exist provided that it can achieve to subordinate all the dynamics of the global politics to itself.

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

与拉曼回声上的所有开车的地，一种三脚架类型原子 systemquickly 从有损耗的激动的水平演变为黑暗州的 decoupled。黑暗在 acomplicated 在地 Rabi 频率，自发的腐烂率，和起始的原子人口上 dependsstrongly 说方法。分析结果表明它是有它的 threecomponents 的一个六倍的退化黑暗状态由于人口再分配 fromspontaneous 排放协调地并且无条理地迭加。

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.