Primary Reasoning behind the Double ITCZ Phenomenon in a Coupled Ocean-Atmosphere General Circulation Model

This paper investigates the processes behind the double ITCZ phenomenon, a common problem in Coupled ocean-atmosphere General Circulation Models (CGCMs), using a CGCM—FGCM-0 (Flexible General Circulation Model, version 0). The double ITCZ mode develops rapidly during the ?rst two years of the integration and becomes a perennial phenomenon afterwards in the model. By way of Singular Value Decomposition (SVD) for SST, sea surface pressure, and sea surface wind, some air-sea interactions are analyzed. These interactions prompt the anomalous signals that appear at the beginning of the coupling to develop rapidly. There are two possible reasons, proved by sensitivity experiments: (1) the overestimated east-west gradient of SST in the equatorial Paci?c in the ocean spin-up process, and (2) the underestimated amount of low-level stratus over the Peruvian coast in CCM3 (the Community Climate Model, Version Three). The overestimated east-west gradient of SST brings the anomalous equatorial easterly. The anomalous easterly, a?ected by the Coriolis force in the Southern Hemisphere, turns into an anomalous westerly in a broad area south of the equator and is enhanced by atmospheric anomalous circulation due to the underestimated amount of low-level stratus over the Peruvian coast simulated by CCM3. The anomalous westerly leads to anomalous warm advection that makes the SST warm in the southeast Paci?c. The double ITCZ phenomenon in the CGCM is a result of a series of nonlocal and nonlinear adjustment processes in the coupled system, which can be traced to the uncoupled models, oceanic component, and atmospheric component. The zonal gradient of the equatorial SST is too large in the ocean component and the amount of low-level stratus over the Peruvian coast is too low in the atmosphere component.

Simulation of double cold cores of the 35°N section in the YellowSea with a wave-tide-circulation coupled model

Based on the MASNUM wave-tide-circulation coupled numerical model, the temperature structure along 35°N in the Yellow Sea was simulated and compared with the observations. One of the notable features of the temperature structure along 35°N section is the double cold cores phenomena during spring and summer. The double cold cores refer to the two cold water centers located near 122°E and 125°E from the depth of 30m to bottom. The formation, maintenance and disappearance of the double cold cores are discussed. At least two reasons make the temperature in the center (near 123°E) of the section higher than that near the west and east shores in winter. One reason is that the water there is deeper than the west and east sides so its heat content is higher. The other is invasion of the warm water brought by the Yellow Sea Warm Current (YSWC) during winter.This temperature pattern of the lower layer (from 30m to bottom) is maintained through spring and summer when the upper layer (0 to 30m) is heated and strong thermocline is formed. Large zonal span of the 35°N section (about 600 km) makes the cold cores have more opportunity to survive. The double cold cores phenomena disappears in early autumn when the west cold core vanishes first with the dropping of the thermocline position.

高斯型耦合Tavis-Cummings模型中原子的量子特性

研究了原子与光场的耦合系数呈高斯型调制的双原子Tavis-Cummings模型中原子的量子特性。通过数值计算,分析了原子垂直于腔轴的运动以及系统初态对双原子能级布居数反转和双原子偶极压缩的影响。结果表明,原子垂直于腔轴的运动影响双原子能级布居数反转的崩塌和回复,但不改变双原子偶极压缩的最大压缩量,只改变最大压缩次数。光场初态为真空态,而两原子初始处在特定的非最大纠缠态时,双原子偶极压缩最大。

Multi-model Projection of July–August Climate Extreme Changes over China under CO_2 Doubling. Part I: Precipitation

Potential changes in precipitation extremes in July–August over China in response to CO 2 doubling are analyzed based on the output of 24 coupled climate models from the Twentieth-Century Climate in Coupled Models （20C3M） experiment and the 1% per year CO 2 increase experiment （to doubling） （1pctto2x） of phase 3 of the Coupled Model Inter-comparison Project （CMIP3）. Evaluation of the models’ performance in simulating the mean state shows that the majority of models fairly reproduce the broad spatial pattern of observed precipitation. However, all the models underestimate extreme precipitation by ～50%. The spread among the models over the Tibetan Plateau is ～2–3 times larger than that over the other areas. Models with higher resolution generally perform better than those with lower resolutions in terms of spatial pattern and precipitation amount. Under the 1pctto2x scenario, the ratio between the absolute value of MME extreme precipitation change and model spread is larger than that of total precipitation, indicating a relatively robust change of extremes. The change of extreme precipitation is more homogeneous than the total precipitation. Analysis on the output of Geophysical Fluid Dynamics Laboratory coupled climate model version 2.1 （GFDL-CM2.1） indicates that the spatially consistent increase of surface temperature and water vapor content contribute to the large increase of extreme precipitation over contiguous China, which follows the Clausius–Clapeyron relationship. Whereas, the meridionally tri-polar pattern of mean precipitation change over eastern China is dominated by the change of water vapor convergence, which is determined by the response of monsoon circulation to global warming.

Multi-Model Projection of July–August Climate Extreme Changes over China under CO_2 Doubling. Part II: Temperature

This is the second part of the authors’ analysis on the output of 24 coupled climate models from the Twentieth-Century Climate in Coupled Models （20C3M） experiment and 1% per year CO 2 increase experiment （to doubling） （1pctto2x） of phase 3 of the Coupled Model Inter-comparison Project （CMIP3）. The study focuses on the potential changes of July–August temperature extremes over China. The pattern correlation coefficients of the simulated temperature with the observations are 0.6–0.9, which are higher than the results for precipitation. However, most models have cold bias compared to observation, with a larger cold bias over western China （5°C） than over eastern China （2°C）. The multi-model ensemble （MME） exhibits a significant increase of temperature under the 1pctto2x scenario. The amplitude of the MME warming shows a northwest–southeast decreasing gradient. The warming spread among the models （～1°C– 2°C） is less than MME warming （～2°C–4°C）, indicating a relatively robust temperature change under CO 2 doubling. Further analysis of Geophysical Fluid Dynamics Laboratory coupled climate model version 2.1 （GFDL-CM2.1） simulations suggests that the warming pattern may be related to heat transport by summer monsoons. The contrast of cloud effects also has contributions. The different vertical structures of warming over northwestern China and southeastern China may be attributed to the different natures of vertical circulations. The deep, moist convection over southeastern China is an effective mechanism for ＂transporting＂ the warming upward, leading to more upper-level warming. In northwestern China, the warming is more surface-orientated, possibly due to the shallow, dry convection.

高斯型耦合多光子Tavis-Cummings模型中原子的量子特性

研究了多光子跃迁过程高斯型耦合Tavis-Cummings模型中原子的量子特性.运用了数值计算方法,讨论了多光子跃迁过程中,原子运动速度、光场初态的平均光子数、跃迁光子数对双原子能级布居数反转和双原子偶极压缩的影响.结果表明,原子运动速度的变化改变了双原子能级布居数反转和双原子偶极压缩与光场的有效作用时间.跃迁光子数的变化改变了双原子能级布居数反转和双原子偶极压缩时间演化曲线的振荡幅度和振荡频率.

不同起爆条件下双钢壁LNG储罐抗爆性能分析

由于双钢壁储罐具有建造周期短、投资小等优点,在LNG储存中应用越来越广泛,但其易在外罐受到外部冲击时引发内罐的破坏。为了分析储罐在不同外爆载荷条件下的破坏行为,以双钢壁LNG储罐为研究对象,考虑内、外罐及保冷材料之间的载荷传递与相互作用,建立了外罐-保冷材料-内罐多介质的多相耦合有限元模型,并对多影响因素下储罐在外爆载荷作用下的破坏进行了分析,探究其抗爆性能。结果表明:在外爆载荷作用下,内、外罐从迎爆面中心向内凹陷直至发生破坏,最大应力均在迎爆面中心,且越靠近中心应力值越大;内、外罐材料均先达到屈服强度后发生塑性变形,随后达到失效应变值并发生破坏;与外罐相比,内罐发生破坏的时间晚42.9%,变形范围和破坏范围分别小12.3%、6.7%;储罐的抗爆性能随着储存液位的升高和罐体容积的增大而增强,随着起爆位置从罐壁中心向上、下两侧移动而提高,在罐壁中心起爆时储罐的破坏程度最大。该研究成果可为双钢壁LNG储罐的设计和储存液位的控制等方面提供理论参考依据。

CRTSⅠ型双块式无砟轨道混凝土抗裂技术研究

CRTSⅠ型双块式无砟轨道受施工工艺及环境因素等影响,在一些薄弱环节易产生裂缝,影响高铁运营,引发安全事故。根据CRTSⅠ型无砟轨道预埋轨枕周边约束条件、底座板、道床板结构受力特点,平衡改善结构收缩变形和收缩应力,建立“水化-温度-湿度-约束-应力”多场耦合开裂风险模型,采用多场耦合模型、抗裂风险预控、抗裂措施管控、实时原位监测、动态措施保障相结合的方法,解决了CRTSⅠ型双块式无砟轨道混凝土裂缝病害,保证了混凝土结构施工质量。

Coupled Heat Transfer Simulation of the Spiral Water Wall in a Double Reheat Ultra-supercritical Boiler

This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m^2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers.

基于双磁场耦合式无线电能传输的WPT系统研究

无线电能传输(WPT)被广泛用于飞机、电动汽车、手机等领域,磁耦合谐振技术(Magnetic Coupling Resonance,MCR)是实现WPT的技术手段之一,具有效率高、传输距离远等优势。针对传统MCR技术的单线圈传输系统输出功率有限的缺点,采用一种前级双线圈传输系统,前级利用两个线圈进行并联,同时进行双磁场耦合谐振式电能传输,共同给负载供电,以期输出功率放大。同时,采用模型预测控制方法对逆变器进行控制,利用模型预测控制的高抗扰性去优化WPT系统的稳定性。仿真和实验验证了所提系统的有效性。

基于产量递减与LSTM耦合的常压页岩气井产量预测

针对常压页岩气井产气递减规律不明确、预测困难等问题,将产量递减模型与机器学习方法相结合,建立了一种新的页岩气井产量递减模型与LSTM(长短时间记忆神经网络)模型耦合预测方法。首先,依据页岩气井产水特点将南川常压页岩气井分为2类,类型1气井早期气水同产,后期产水明显减少,类型2气井长时间气水同产;其次,基于双对数诊断曲线和特征曲线明确气井的流动阶段,并采用7种常用的气井产量递减模型对不同类型页岩气井进行产量分析;最后,将递减模型的误差作为LSTM模型的输入,叠加得到耦合方法下产量预测。结果表明:拟稳态流动阶段的类型1的X1气井,优选递减模型为改进双曲递减模型和AKB递减模型,线性流动阶段的类型2的X2气井,优选SEPD(扩展指数递减)模型和Duong递减模型;对于递减模型误差较大时,耦合LSTM模型后,页岩气井产量预测精度明显提高,而递减模型误差较小时效果不显著。

双块式无砟轨道轨枕伤损对轨道结构性能的影响

为探明双块式无砟轨道轨枕伤损对轨道结构动力响应以及高速列车行车性能的影响,建立考虑局部轨枕伤损的车辆-双块式无砟轨道系统动力学耦合模型,分别对直线地段和曲线地段的轨枕伤损模式、伤损范围等因素进行仿真分析。结果表明:轨枕伤损导致单个扣件锚固性能失效对轮轨相互作用力和行车安全性指标影响较小,而连续3个扣件锚固性能失效使得轮轨垂向力、轮重减载率、钢轨垂向位移与振动加速度显著增加;轨枕挡肩失效对轮轨相互作用力影响不大,主要导致钢轨横向变形和横向振动加速度增大;曲线地段单侧轨枕失效主要对失效一侧的轮轨力产生不利作用,轮轨横向力增幅明显,从而导致脱轨系数增大。为保障高速列车行车安全,双块式无砟轨道轨枕锚固或挡肩连续失效个数不宜超过3个。

球面配流副油膜动态耦合建模及求解方法

柱塞泵摩擦副多场耦合建模及求解是柱塞泵失效机理研究及可靠性提升的基础,针对双斜式柱塞泵球面配流副多场耦合模型求解难的问题,提出油膜厚度场-压力场-温度场动态耦合模型及求解方法。在球面配流副受力分析的基础上结合雷诺方程和能量方程建立球面配流副油膜厚度场-压力场-温度场耦合模型;基于有限差分法和牛顿迭代法求解动态耦合模型,温度场、压力场、厚度场间相互耦合变化;通过仿真求解,与现有模型进行对比,结果相近且更符合实际,验证了所提模型及求解方法的有效性。

基于SCIR双层耦合网络的信息学教育培训市场发展策略分析——以徐州市为例

在“双减”政策背景下,针对徐州市信息学教育培训市场的发展现状,对当地群众开展了问卷调查,并对调查数据进行统计分析,总结出信息学教育遇到的问题。基于SCIR模型构建双层耦合网络,模拟徐州市学生参与信息学线上培训和线下培训的人数变化,通过建模仿真,得出在后疫情时代参与网络教育的人数将超越传统教育的人数,同时政府的引导能够有效地推动信息学教育的发展。最后通过仿真结果分析信息学教育发展前景,针对各个群体给出相应的建议,对徐州市信息学教育培训市场的发展具有重要意义。

Vector radiative transfer numerical model of coupled ocean-atmosphere system using matrix-operator method

A vector radiative transfer numerical model of the coupled ocean-atmosphere system is developed based on the matrix-operator method, which is named PCOART. Using the Fourier analysis, the vector radiative transfer equation (VRTE) is separated into a set of equations depending only on the observa-tion zenith angle. Using the Gaussian-Quadrature method, VRTE is finally transferred into the matrix equation solved by the adding-doubling method. According to the reflective and refractive properties of the ocean-atmosphere interface, the vector radiative transfer numerical model of the ocean and at-mosphere is coupled in PCOART. Compared with the exact Rayleigh scattering look-up tables of MODIS (Moderate-resolution Imaging Spectroradiometer), it is shown that PCOART is an exactly numerical model, and the processing methods of the multi-scattering and polarization are correct. Also, validated with the standard problems of the radiative transfer in water, it is shown that PCOART can be used to calculate the underwater radiative transfer problems. Therefore, PCOART is a useful tool for exactly calculating the vector radiative transfer of the coupled ocean-atmosphere system, which can be used to study the polarization properties of the radiance in the whole ocean-atmosphere system and the remote sensing of the atmosphere and ocean.

基于新型轴对称无网格方法的水下爆炸冲击波和气泡运动数值模拟

采用无网格光滑粒子流体动力学(smooth particle hydrodynamics,SPH)方法,结合粒子体积自适应技术(volume adaptive scheme, VAS)构建高精度、高效率的新型轴对称SPH模型,实现水下爆炸冲击波和气泡运动模拟。在冲击波传播阶段,通过与经验公式及文献理论值对比,验证了该轴对称SPH模型的精度。针对气泡脉动模拟,选取典型的双气泡耦合问题,分析气泡形态和压力载荷的力学特性,讨论了两气泡之间的距离参数对气泡相互作用过程的影响。结果表明,该新型轴对称SPH模型可实现水下爆炸过程压力载荷和气泡形态演化的精确预报。

基于DDPG算法的电动拖拉机双电机耦合传动 参数优化

针对电动拖拉机双电机耦合传动系统中,驱动电机与PTO电机耦合驱动时传动系统各档之间传动比优化的问题,提出一种考虑电机耦合规律的传动系统速比动态优化方法。通过设计传动系统速比最小,电机耦合效率最高和达到设计工况时间最短的目标函数,借助Simscape搭建拖拉机传动系统模型与Simulink中创建的驾驶员模型、电机模型、控制器模型和拖拉机车身模型组成仿真环境;采用DDPG(强化学习)算法在连续动作空间内对传动系统进行迭代求出最优值。与静态优化相比结果表明:在运输模式下,传动比下降0.7,拖拉机从0~20 km/h加速时间提前0.3 s,电机综合效率提升10%。在旋耕模式下,传动比下降1.6,拖拉机从0~15 km/h加速时间提前1 s,电机综合效率提升5%。

3/12相双绕组发电机数学模型研究

介绍了3/12相交直流同时供电(双绕组)发电机的结构特点。在某些近似假设条件下,将 12 相4Y互移15直流绕组等效为一个3相Y绕组,然后通过适当处理两套绕组之间的耦合,得出了与耦合有关的参数间的相互关系,从而简化了d-q-0 系统的数学模型、导出了简明的电压和磁链方程及相应的d和q轴等效电路,为分析该类电机的各项性能奠定了坚实的理论基础。该文所用方法同样适用于其它结构的双绕组发电机。

六相交直流同时供电发电机直流侧突然短路电流分析

通过适当处理六相交直流同时供电 (双绕组 )发电机两基金项目 :国家自然科学基金资助项目 ( 5 97770 0 7)。ProjectSupportedbyNationalNaturalScienceFoundationofChina( 5 97770 0 7) .套绕组之间的耦合 ,建立了其d q 0系统的简化数学模型 ;在此基础上 ,应用海维赛德运算微积法和叠加原理 ,分析了其稳态和直流侧突然短路运行 ,给出了定子和转子的时间常数以及交流侧完整的短路电流表达式 ;通过适当简化处理 ,得出了估算交、直流侧最大冲击电流和最大电流到达时刻的计算公式 ,并与普通三相电机突然短路的最大电流估算公式进行了比较 ,得出了到达最大电流时刻提前的结论 ;通过试验验证该文所得结果。该文对两套绕组之间耦合的处理大大简化了双绕组发电机的数学模型 ,为分析双绕组发电机的其它性能奠定了基础 ;所得结论和所用方法同样适用于其它结构的双绕组发电机 ,具有普遍意义。

12/3相双绕组感应发电机的谐波不对称分析

励磁调节器所引入的谐波电流会引起12相功率绕组的不对称工作。为了研究谐波不对称的产生机理,该文在建立基于基波的12/3相双绕组感应电机dq0模型的基础上,通过对两套绕组间的谐波耦合分析,经过简化,得出了可用于谐波分析的等效电路模型。从中得到了规律性的认识,为该类电机的设计和推广起到了促进作用。试验与理论分析结果的对比说明了所建模型和分析方法的正确性。