联合GNSS与GRACE/GRACE-FO数据反演中国西南地区陆地水储量变化

GNSS和重力恢复与气候试验(GRACE)及其后续任务(GRACE-FO)给陆地水储量变化(TWSC)研究带来了技术革新,但这两种技术估计的区域TWSC具有不同的时空尺度和精度特性。因此,有必要融合两种观测数据,以获得同一尺度且高精度的TWSC。本文基于GNSS独立反演模型,使用求和算子对喷气推进实验室(JPL)的GRACE/GRACE-FO Mascon数据进行求和运算来构建约束,通过赤池贝叶斯准则选择最优模型参数,构建了一种联合GNSS与GRACE/GRACE-FO数据的区域TWSC反演模型。随后,本文设计数值模拟试验,以验证利用该模型反演中国西南地区TWSC的可行性。结果显示,1000次试验中联合反演估算的均方根误差均值为10 mm,比GNSS独立反演结果低47%。基于此方法,本文联合GNSS与JPL Mascon数据反演了中国西南地区2011年1月—2022年6月的时变TWSC。对比联合反演、GNSS独立反演、GRACE/GRACE-FO和高分辨率全球陆地数据同化系统(GLDAS)的结果,发现联合反演与GLDAS的TWSC周年振幅空间分布特征最吻合,表明联合反演估计的TWSC空间分辨率优于GNSS独立反演和GRACE的结果。最后,结合水平衡方程估算的区域水文收支情况,并通过广义三角帽方法评估陆地水储量等效水柱高的变化率(d(EWH)/d t)的不确定性。结果显示,联合反演估计的d(EWH)/d t不确定性为8 mm/月,较GRACE/GRACE-FO、GNSS独立反演和水平衡方程结果分别低33%、68%和62%。研究结果表明,与GNSS和GRACE/GRACE-FO独立反演方法相比,联合反演能够改善TWSC估值的精度,可为水资源管理决策及水文气候学研究提供更可靠的数据支撑。

Anderson's Motives for Exploring Man's Frustration

Man's frustration is a dominant theme in Anderson's short stories.It is the condensation of his impressions of American life.His motives for exploring the problem include:to reveal the painful experience,feeling and situation of ordinary people during the economic,social and cultural transformations of America;to remind the reader of the choking effects of outworn conventional morality and the destructive effects of modern industrial materialism;to draw the reader's attention to the emotional life of the ordinary people;and to express his own views on and attitudes toward humanity and society.

District Partisan Homogeneity, Communications, and the Electoral Motive: An Analysis of the Facebook Posts of Members of the U.S. House of Representatives

The research examines the way in which members of the U.S. House of Representative represent themselves on the social network site Facebook. Each member’s activity is observed on seven different occasions and the frequency and substantive character of posts made during the second half of 2013 are established. The focus is on position-taking posts versus posts which mention the district the member serves in. Our expectation is that members from electorally safe districts will be more likely to advertise their policy positions while members from marginal districts will be more inclined to advertise their district connections. We control for minority party status, gender, and ideological extremism among other concerns and learn electoral safety is a good predictor of both “position-taking” and “district mentions”. Consistent with an electoral motive, we also find members from the minority party less likely to take positions on the issues of the day and more likely to mention the district they serve in.

LPS'S CRITERION FOR INCOMPRESSIBLE NEMATIC LIQUID CRYSTAL FLOWS

In this paper we derive LPS＇s criterion for the breakdown of classical solutions to the incompressible nematic liquid crystal flow, a simplified version of Ericksen-Leslie system modeling the hydrodynamic evolution of nematic liquid crystals in R^3. We show that if 0 〈 T 〈 ＋∞ is the maximal time interval for the unique smooth solution u ∈ C^∞（[0, T）,R^3）,then ｜u｜＋｜△d｜∈L^q（[0,T],L^p（R^3））,where p and q satisfy the Ladyzhenskaya-Prodi-Serrin＇s condition：3/p＋2/q=1 and p∈（3,＋∞].

Numerical analyses of pillar behavior with variation in yield criterion,dilatancy, rock heterogeneity and length to width ratio

With recent advances in numerical modeling, design of underground structures increasingly relies on numerical modeling-based analysis approaches. While modeling tools like the discrete element method(DEM) and the combined finite-discrete element method(FDEM) are useful for investigating small-scale damage processes, continuum models remain the primary practical tool for most field-scale problems.The results obtained from such models are significantly dependent on the selection of an appropriate yield criterion and dilation angle. Towards improving its capabilities in handling mining-related problems, the authors have previously developed a new yield criterion(called progressive S-shaped criterion). The focus of the current study is to demonstrate its use in modeling rock pillars through a comparative analysis against four other yield criteria. In addition to the progressive S-shaped criterion,only one out of the four other criteria predicted a trend in strength consistent with an empirical pillar strength database compiled from the literature. Given the closely-knit relationship between yield criteria and dilation angle in controlling the overall damage process, a separate comparison was conducted using a mobilized dilation model, a zero degree dilation angle and a constant non-zero dilation angle. This study also investigates the impact of meso-scale heterogeneity in mechanical properties on the overall model response by assigning probability distributions to the input parameters. The comparisons revealed that an isotropic model using a combination of progressive S-shaped criterion and mobilized dilation angle model is sufficient in capturing the behaviors of rock pillars. Subsequently, the pillar model was used to assess the effect of L/W(length/width) ratio on the peak strength.

Strength criterion of porous media: Application of homogenization techniques

The present paper aims at giving some general ideas concerning the micromechanical approach of the strength of a porous material. It is shown that its determination theoretically amounts to solving a nonlinear boundary value problem defined on a representative elementary volume(REV). The principle of nonlinear homogenization is illustrated based on the case of a solid phase having a Green’s strength criterion. An original refinement of the so-called secant method(based on two reference strains) is also provided. The paper also describes the main feature of the Gurson’s model which implements the principle of limit analysis on a conceptual model of hollow sphere. The last part of the paper gives some ideas concerning poromechanical couplings.

Absolutely Stable of Takagi-Sugeno Fuzzy Control System by Using Popov’s Criterion

In this paper, we presented a sufficient condition on the frequency domain for the absolutely stable analysis of the Takagi-Sugeno (T-S)fuzzy control system, based on the Popov’s criterion. we use some numerical examples to illustrate the efficiency of frequency domain-based condition.

Motivations of Using Social Media Through Smartphones Among University Students in the United Arab Emirates

The aim of the study was to investigate gratifications of using social media among university students in the United Arab Emirates. Adopting the uses and gratification approach, the study investigates how the students utilize social media to gratify their personal, social, psychological, and educational needs. The study uses a questionnaire to collect data from a sample of 420 students from two universities in the UAE: University of Sharjah and Zayed University. In each university, two colleges were selected to represent art colleges and sciences colleges. The findings of the study show that 69.3% of the students are accessing social media more than five hours daily. 79.0% of the students access the social media through their smartphones. The main social media accessed are WhatsApp, Instagram, and Facebook. The main reasons of using social media are seeking information, communicating with friends, consuming time, and following up public affairs.

Motivating English Students in Class

Motivation plays a key role in English language learning. This study briefly discusses the main concepts on this issue and aims to present teaching implications for EFL classes in China. These implications are related to the motivation which can be inspired by appropriate tasks, the teacher＇s role and feedback.

Relations between cubic equation, stress tensor decomposition, and von Mises yield criterion

Inspired by Cardano＇s method for solving cubic scalar equations, the addi- tive decomposition of spherical/deviatoric tensor （DSDT） is revisited from a new view- point. This decomposition simplifies the cubic tensor equation, decouples the spher- ical/deviatoric strain energy density, and lays the foundation for the von Mises yield criterion. Besides, it is verified that under the precondition of energy decoupling and the simplest form, the DSDT is the only possible form of the additive decomposition with physical meanings.

Does Motivation Predict Persistence and Academic Success?

This study researches the relationship between motivation and academic success as measured by the Valence, Instrumentality, and Expectancy Scale. Utilizing Vroom’s Expectancy Theory as the framework, the research assesses the responses of 375 nurse assistant students in the state of Illinois to evaluate the self-report of the constructs of Vroom’s Expectancy theory in relation to their performance on a standardized high stakes test.

Herzberg’s Motivation Theory in Workplace

In this review authors will analyze Herzberg’s motivation theory as one of the content theories of motivation.It attempts to explain the factors that motivate individuals through identifying and satisfying their individual needs,desires,and the aims pursued to satisfy these desires.This theory of motivation is known as a two-factor content theory.It is based upon the deceptively simple idea that motivation can be dichotomized into hygiene factors and motivation factors and is often referred to as a“two-need system”.These two separate“needs”are the need to avoid unpleasantness and discomfort and,at the other end of the motivational scale,the need for personal development.A shortage of the factors that positively encourage employees(the motivating factors)will cause employees to focus on other,non-job related“hygiene”factors.The most important part of this theory of motivation is that the main motivating factors are not in the environment but in the intrinsic value and satisfaction gained from the job itself.It follows therefore that to motivate an individual,a job itself must be challenging,have scope for enrichment,and be of interest to the jobholder.Motivators(sometimes called“satisfiers”)are those factors directly concerned with the satisfaction gained from a job.

Motivations of Individuals Participating in Social Media： A Cultural Perspective

Social media is an information technology that allows users to communicate and share information. With steadily rising number of users across the globe, individuals participate in various activities, like connecting with friends and community members, sharing information, posting political messages, disaster recovery activities, reading daily news, learning, and entertainment, each driven by different sets of motivations. Culture has an influence on the kind of motivation―pro-social and personal needs oriented―that drives social media usage by individuals. Using Hofstede’s （1984b） cultural dimensions, the paper suggests that each of the dimensions will have influences on the social media behaviors differently. Such a cultural perspective helps future social media users to plan the kind of activity and information sharing based on the kind of motivation driving the target audience and the platform providers to design and market accordingly.

An analysis of the motivational effect on employees of Maslow＇s Hierarchy of Needs in international culture circumstances

Maslow＇ s Hierarchy of Needs, which is one of the important motivation theories, has become a strategy used by managers to motivate employees. The project will explain the definition of motivation and Maslow＇ s Hierarchy of Needs from the perspective of organizational behavior and the strengths and weaknesses of the theory. Then it will consider how the theory is applied effectively in the USA and Northwest Europe and ineffectively in some developing and undeveloped countries with different economical backgrounds, political systems and cultural preferences. The conclusion suggests that managers should choose motivation systems that fit in the local cultural backgrounds.

一种AES S盒改进方案及其硬件设计

为提高高级加密标准(advanced encryption standard, AES)算法的安全性,提出了一种新的S盒生成方案。在分析了现有S盒存在的问题后,基于S盒的构造原理和密码学性质,通过选择新的不可约多项式和仿射变换对,同时调整仿射变换与乘法逆的运算顺序,构造出一种新的S盒;对生成的新S盒与AES的S盒以及其他改进S盒在代数式项数、严格雪崩标准距离等方面进行了比较,结果显示,新S盒具有更好的代数性质,能够有效抵御代数攻击;还对新S盒进行了硬件设计并优化,DC综合结果显示新S盒复域优化实现消耗的资源比传统复域实现少12%,比查找表法实现少41%。新S盒在安全性方面优于现有S盒,将其应用于AES软件设计和硬件设计,并通过仿真测试验证了其正确性。

Stability analysis of the simplest Takagi-Sugeno fuzzy control system using circle criterion

A frequency-domain-based sufficient condition is derived to guarantee the globally asymptotic stability of the simplest Takagi-Sugeno （T-S） fuzzy control system by using the circle criterion. The analysis is performed in the frequency domain, and hence the condition is of great significance when the frequency-response method, which is widely used in the linear control theory and practice, is employed to synthesize the simplest T-S fuzzy controller. Besides, this sufficient condition is featured by a graphical interpretation, which makes the condition straightforward to be used. Comparisons are drawn between the performance of the simplest T-S fuzzy controller and that of the linear compensator. Two numerical examples are presented to demonstrate how this sufficient condition can be applied to both stable and unstable plants.

基于SAIC方法的纵向数据模型平均

传统的SAIC模型平均所需运行时间随数据维数而呈现出阶乘级的增长,其预测精度也随之下降.本文基于传统SAIC模型平均法进行了改进,提出一类基于SAIC加权法的纵向数据模型平均法,使运算效率大幅提升,并且使预测效果拥有良好的稳定性.模拟实验结果表明,与传统方法相比,在预测残差平方和层面,本文提出的新模型在稳定性、精准性和运行速度方面均优于传统方法.

利用Yabuki & Matsu′ura反演方法计算2011年日本东北地区太平洋海域M_w9.0级地震同震滑动分布

Yabuki&Matsu′ura反演方法是利用ABIC最佳模型参数选取方法和平滑的滑动分布作为约束条件,由形变观测数据计算发震断层滑动分布.本文基于日本列岛同震GPS观测数据和发震断层曲面构造模型,利用Yabuki&Matsu′ura反演方法计算2011年日本东北地区太平洋海域Mw9.0级地震的发震断层同震滑动分布.反演结果表明,断层面上的最大滑动量为35m,较大滑动分布在浅于30km的震源中心上部,最大破裂集中在20km深度的地方.其地震矩约为3.63×1022 N.m,对应的矩震级为Mw9.0.模拟结果显示Yabuki&Matsu′ura反演方法更适用于倾角低于40°的断层模型反演.最后,本文基于上述方法获得的发震断层滑动模型,利用地球体位错理论正演计算该地震在中国及其邻区产生的远场形变,正演计算结果基本可以解释由中国GPS陆态网络观测到的同震形变.

基于多重映射的安全S盒构造方法

将构造S盒的问题转化为寻找满足一定条件的映射的问题。利用Tent映射的混沌特性,提出初始映射算法,并使用该算法得到可作为初始S盒的初始映射。为了提高S盒的安全性,提出了使用多个初始映射对初始S盒做非线性操作的多重映射算法,经安全性准则检验,该算法能够获得安全性更高的S盒。最后通过设定一个安全指标统计了该算法能够生成的优良S盒的个数,表明优良S盒的个数随着算法采用初始映射个数的增加而增加,并且实现算法所需的时间与算法中采用的初始映射的个数成正比。

应用Sheard准则评估集合不足患者的临床研究

目的:运用Sheard准则对集合不足的屈光不正患者的双眼视失平衡症状进行评估和诊治。方法:对2009-06以来18例集合不足的患者进行眼屈光检查,同时检测远近分离性隐斜,远近辐辏,正相对调节,调节状态,负相对调节,辐辏近点,调节幅度等眼动参数。计算AC/A参数,检测其对Sheard准则符合性,并利用该准则计算所需的棱镜处方。结果:近距棱镜不符合Sheard准则有14例(78%),其所需的基底朝内棱镜度数为(3.47±2.83)△。结论:临床上运用Sheard准则可有效地评估和诊治近距离用眼不适的集合不足患者。