A Study on the Nonlinear Stability of Fronts in the Ocean on a Sloping Continental Shelf

The baroclinic nonlinear stability of fronts in the ocean on a sloping continental shelf is studied, the model equations, called the frontal geostrophic model, developed by Cushman—Roisin et al.(1992) for describing the dynamics of surface density fronts in the ocean are developed and the two—layer frontal geostrophic model for fronts on a sloping continental shelf is first obtained. The nonlinear stability criteria for the fronts on a sloping bottom are obtained by using Arnol’d (1965, 1969) variational principle and a prior estimate method. It is shown that our result is better than the former works. Key words Fronts in the ocean - Frontal geostrophic model - Nonlinear stability This Work was supported by “ the National Key Programme for Developing Basic Sciences” G199804901-1 and the National Natural Science Foundation of China “ Research Programme for Excellent State Key Laboratory” under Grant No. 49823002 and No. 49805002.

On the stability of fronts near shelfbreak

Using a two-dimensional semi-geostrophic model. the stability of fronts near shelf break (shelfbreak font, western boundary current front) and its mechanism are studied. We find that the stability of the front is related to the frontal structure. In general, the increase of the lower layer depth lowers the unstable growth rate (a1). (1) The shelfbreak front is baroclinically unstable and ai increases with the increase of the bottom slope, different from the conclusion of Flagg and Beardsley (1978). (2) A western boundary current front with uniform vorticity in the upper layer is barotropically unstable, due to the strong horizontal shear of the mean current. The unstable growth rate of this front for a realistic topography is only one seventh of that of the flat bottom case. (3) For a western boundary current front with hyperbolic tangent structure, we find its wave propagation speed to be about 0. 5 m/s, in agreement with the observed values. The front is baroclinically unstable. (4)The unstable growth rate of a domed structure front and its wave speed do not seem to be related to its wavelength. The front is baroclinically unstable.

Cellular Chemical Field and Cellular Homeostasis

1.Introduction Cell structure and function are controlled by a complex regulatory networking process,in which molecular adaptation and interaction are essential to maintain cellular homeostasis following dynamic multi-omics rules and multi-systematic changes.This complex chemical process is an important mechanism for stabilizing the cell microenvironment.

STABILITY OF TIME-PERIODIC TRAVELING FRONTS IN BISTABLE REACTION-ADVECTION-DIFFUSION EQUATIONS

This paper is concerned with the global exponential stability of time periodic traveling fronts of reaction-advection-diffusion equations with time periodic bistable nonlinearity in infinite cylinders. It is well known that such traveling fronts exist and are asymptotically stable. In this paper, we further show that such fronts are globally exponentially stable. The main difficulty is to construct appropriate supersolutions and subsolutions.

Macroregulation in all-around recovery:Maintain stability and orient to long-term priorities

Since last October, loose monetary and credit policies and the stimulus package have produced desired results. The economy has entered into a "V-shaped" recovery in the second quarter of this year after hitting the bottom in the first quarter, with various economic indicators rising fast, rescue missions completed and short-term objectives basically met. In this context, the next step of macro-regulation should focus on long-term objectives, speed up institutional innovation and restructuring, control the intensity, pattern and pace of short-term policy loosening and prevent inflation and wild swings in the economy so as to achieve a new round of sustained and rapid economic growth.

Multidimensional Governance Logic and Path to Maintain Social Stability

With China’s reform and development entering a critical period,the interweaving of various interest relations and the superimposing of the old and new contradictions have intensified social risks.Based on the concept of“pluralism,sharing,participation,cooperation and tolerance”,social stability can be maintained by the balanced protection of civil rights and the full realization of the development strategy.In addition,with the guidance of comprehensive legal thinking and core socialist values,the legal regulation of administrative behavior and rights-protection behavior is strengthened.In this way,the win-win of maintaining rights and stability can be realized in the positive-sum game that will help resolve social risks and achieve high-quality social stability.

On stability of elastic domain during isothermal solid-solid phase transformationin a tube configuration

Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation （during loading） and vanishing （in unloading） of a high strain （martensite） domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales （the normalized tube length and normalized wall-thickness） and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model.

LOCAL STABILITY OF TRAVELLING FRONTS FOR A DAMPED WAVE EQUATION

The paper is concerned with the long-time behaviour of the travelling fronts of the damped wave equation αutt ＋ut = uxx -V′（u） on R. The long-time asymptotics of the solutions of this equation are quite similar to those of the corresponding reaction-diffusion equation ut = uxx - V′（u）. Whereas a lot is known about the local stability of travelling fronts in parabolic systems, for the hyperbolic equations it is only briefly discussed when the potential V is of bistable type. However, for the combustion or monostable type of V, the problem is much more complicated. In this paper, a local stability result for travelling fronts of this equation with combustion type of nonlinearity is established. And then, the result is extended to the damped wave equation with a case of monostable pushed front.

Association between balloon atrial septostomy and prostaglandin E1 therapy until repair of transposition of the great arteries in neonates

The standard of care in the management of d-transposition of the great arteries(TGA)includes the arterial switch operation(ASO).1,2 Although some institutions have begun to publish the results of performing the ASO within the first few hours of life,most centers continue to"electively"delay ASO for several days to allow for a reduction in pulmonary vascular resistance and the stabilization of renal and liver function.1,2 The early initiation of prostaglandin E1(PGE)infusion to maintain ductal patency is a nearly universal component of therapy in order to maintain adequate arterial oxygen saturation and systemic oxygen delivery during the pre-operative period via intercirculatory mixing at the atrial septal and patent ductus arteriosus levels1,3.

Compressible Rayleigh-Taylor Instability with Preheat in Inertial Confinement Fusion

The compressible Rayleigh-Taylor instability of accelerated ablation front is analysed in consideration of the preheat effects, and the corresponding eigen-problem is solved numerically using the fourth-order accurate two- point compact difference scheme. Both the growth rate and perturbation profiles are obtained, and the obtained growth rate is close to the results of direct numerical simulation. Our results show that the growth rate is more reduced and the cutoff wave length becomes longer as preheat increases.

Weak Nonlinearity of Ablative Rayleigh-Taylor Instability

The weakly nonlinear regime of single mode ablative Rayleigh-Taylor instability is studied, with consideration of preheat effect and the width of the ablation front. The Rayleigh-Taylor linear growth rate agrees well with the direct numerical simulation. For the density perturbation, the amplitude distribution of the fundamental mode has one peak value whereas those of the second and third harmonics have two and three peak values, respectively. Harmonics generation versus wave number is also given and it is close to the result of direct numerical simulation.

Dyeing and printing industry:Scientific and technical progress,energy-saving and environmental protection have achieved balanced development Interview with Chen Zhihua,president of China Dyeing and Printing Association

The general operation of dyeing and printing industry maintained a trend of slow stabilization during the 12th Five-Year Program period with obvious results in science and technology,management,energy conservation and environmental protection as well as the balanced development of the industries.Chen Zhihua,president of China Dyeing and Printing Association(CDPA),said that the dyeing and printing industry has in-

Detection of early-stage research fronts——An example of complex networks research

Purpose:This study aims to detect research fronts of a scientific field in its early development stage using bibliometric indicators developed based on the features of research fronts.Design/methodology/approach:We first focused on conceptualization of'research fronts'and outlined 4 indicators to measure different aspects of the concept:Innovation,timeliness,stability and interdisciplinarity.Then research specialties obtained based on direct citation networks were evaluated with the 4 indicators and research fronts were identified.Finally,methodology was illustrated and verified in the research domain of complex networks.Findings:The results indicate that the proposed method is useful in detecting research fronts in a specific field which is at an early development stage.Research limitations:The quality of clustering results was not assessed.It needs to be further studied whether the method can be applicable to the fields that evolve slowly such as mathematics or are highly specialized like entomology and zoology.Practical implications:This study helps researchers keep abreast of emerging trends and policy-makers formulate science and technology policies and strategic plans.Originality/value:This research provides insights into a quantitative assessment method to detect research fronts of a scientific field in its early development stage.

苏州出口贸易保稳提质策略研究——基于深圳和上海出口贸易的经验

出口作为拉动经济增长的三驾马车之一,对属于典型外向型经济的苏州来讲更是如此。然而,作为贸易强市的苏州面临制造业新的竞争优势还未形成、外资企业对出口的贡献不断下降、对主要目标市场的出口不增反降、贸易数字化发展水平较低等出口困境,2023年以来出口贸易额出现了明显下滑。在此情况下,文章研究了深圳和上海出口贸易持续高质量发展的经验,认为苏州应该从强化贸易产业链视角出台组合政策,形成贸易促进合力;大力推动数智技术赋能出口贸易,增强制造业和贸易数字化对出口贸易的支撑力度;加大对民营企业的支持力度,不断提高出口贸易发展韧性;坚持市场多元化策略,降低出口贸易过度依赖少数市场带来的风险。

矢车菊-3-葡萄糖苷提取纯化、生物活性及稳态化技术的研究进展

矢车菊-3-葡萄糖苷(Cyanidin-3-glucoside,C3G)是自然界中分布最为广泛的一种花青素,富含于水果、蔬菜和谷物中,具有抗氧化、抗癌、抗炎以及维持视觉健康等生理功能,在食品、医药等行业备受关注。提取纯化是利用C3G的重要步骤,但C3G在储存、加工过程中易受外界环境的影响而失去原有的颜色和生理价值。为促进C3G在食品领域的应用,该文汇总了C3G在不同食物中的含量及常见的提取纯化方法,概述了C3G抗氧化、抗癌、抗炎以及维持视觉健康等生物活性,并从生物大分子复合和分子修饰两个方面介绍了C3G的稳态化方法,为未来研究和综合开发利用C3G提供理论依据。

水-气耦合下的土质边坡稳定系数场分析

传统边坡稳定性分析方法仅对潜在滑动面进行整体稳定性评估,无法获取各点的安全系数.基于稳定系数场理论,综合考虑水-气耦合作用,对降雨条件下边坡稳定性进行分析.结果表明:1)稳定系数场法能够直观地体现水-气耦合作用下边坡的具体破坏区域,得到各点的安全系数;2)孔隙气压力对边坡降雨入渗有一定阻碍作用,并且随着降雨时间的推移阻渗效果愈明显,相同条件下降雨40 h时,两相流湿润锋深度较单向流减小了28.6%;3)相同条件下,考虑水-气耦合作用将降低边坡稳定性,以降雨40 h为例,两相流边坡失稳面积约为单向流的1.7倍.因此,在实际工程中对边坡稳定性分析时考虑水-气耦合作用,工程偏于安全.

汽车线控转向系统稳定性控制策略研究

以汽车线控转向系统为研究对象,构建滑模观测器对汽车质心侧偏角进行实时估计,用于主动前轮转向控制器设计。以汽车线性二自由度模型为参考模型,设计了基于扰动补偿的主动前轮转向滑模控制器,由主动转向控制器决策出额外附加前轮转角,使车辆响应跟随理想横摆角速度与质心侧偏角,改善汽车的横向稳定性。通过所建立的Carsim和Simulink联合仿真平台,在双移线低路面附着系数,有、无侧向风的工况下验证了主动转向控制策略的有效性。

“反向闹大”式集体行动何以成功——兼论“维稳”意涵的拓展与进阶

进入新时代,随着国家治理体系与治理能力现代化建设水平的不断提高,特别是“人民至上”执政理念的深入践行,国家与社会在“维稳”场域内的互动逻辑发生转变。典型案例研究表明,传统“大闹→闹大”式抗争逻辑的效用呈衰变态势,而“不闹→闹大”的“反向闹大”式集体行动逻辑形成,并取得成功。根本原因在于,新时代国家“维稳”意涵的丰富化,具体表现为:从“机制”到“价值”的进阶、从“秩序”到“人本”的深化、从“事件”到“问题”的拓展。民众从“大闹”到“不闹”的行为选择,触发了国家“维稳”意涵层级的转换,进而引发了政府应对策略的转变与升级。“反向闹大”式集体行动逻辑的提出,丰富了“闹大”议题既有的研究谱系,拓展了研究视野,同时为社会抗争的有效治理提供了新思路。

“稳中求进”工作总基调的历史演进及新时代内涵

“稳中求进”的工作总基调及重要原则,经历了从思想萌芽到逐渐成熟、不断丰富内涵的历史演进,包括计划经济体制下稳定与增长的理论争论,伴随改革开放的理论提出与实践试错。这一理论是习近平治国理政思想的重要组成部分,蕴含着马克思主义辩证法及生产力与生产关系矛盾的运动规律。它包含着以增强风险意识和底线思维为核心,确保经济在合理区间内平稳运行以及社会发展平稳有序的“稳”的主基调,又包含着以供给侧结构性改革为主线,构建新发展格局、加快促进经济增长方式质的转变以及经济社会全面发展的“进”的目标。这一工作总基调和原则,是我国面对未来发展“危”与“机”的应对之策,以全面落实“稳”和“进”之间的融合发展,助力实现中国式现代化。

分布式驱动电动汽车执行器失效容错控制研究

为了提高单电机故障状态下分布式驱动电动汽车的稳定性,提出了一种驱动力重构和主动前轮转向(AFS)结合的容错控制方法。首先,设计滑模控制器,控制输入量为横摆角速度和质心侧偏角,进而对所需横摆力矩和前轮附加转角进行控制。其次,建立电机故障状态下的整车驱动力优化分配模型。当车辆电机出现故障时,运用二次规划算法对各电机转矩进行重构分配。同时,当某一电机发生故障且同侧电机出现输出饱和而无法提供足够的横摆力矩时,通过主动前轮转向提供附加横摆力矩。最终搭建CarSim/Simulink联合仿真模型进行验证,结果显示,所采用的容错控制方法可有效提高车辆稳定性和动力性。