A Novel Approach for Trajectory Tracking Control of an Under-Actuated Quad-Rotor UAV

Dear Editor,This letter presents a novel Udwadia-Kalaba(U-K)approach for the trajectory tracking control of a quad-rotor unmanned aerial vehicle(UAV).Compared to conventional control approaches,the desired trajectories are treated as trajectory tracking constraints in this approach.

Optimization and Characterization of Combined Degumming Process of Typha angustata L. Stem Fibers

Plant derived natural fibers have been widely investigated as alternatives to synthetic fibers in reinforcing polymers.Researchers over the years have explored many plant fibers using different extraction processes to study their physical,chemical,and mechanical properties.In this context,the present study relates to the extraction,characterization,and optimization of Typha angustata L.stem fibers.For this purpose,desirability functions and response surface methodology were applied to simultaneously optimize the diameter(D),linear density(LD);yield(Y),lignin fraction(L),and tenacity(T)of Typha stem fibers.Typha stems have been subjected to both alkali(NaOH)and enzymatic(pectinex ultra-SPL)treatments.Three levels of process variables including enzyme concentration(10,15,and 20 ml/L)and treatment duration(10,15,and 20 days)were used to design the experiments according to the factorial design.Experimental results were examined by analysis of variance and fitted to second order polynomial model using multiple regression analysis.The Derringer’s desirability function released that the values of process variables generating optimized diameter,linear density,yield,lignin ratio and tenacity are 20 ml/L and 20 days for concentration of pectinex ultra-SPL enzyme and treatment duration,respectively.Confirmation was performed and high degree of correlation was found between the experimental and statistical values.Moreover,the morphological structure has been investigated by the scanning electron microscope,showing a crenelated structure of ultimate fiber bundles of cellulose composing the Typha fiber.Compared to Typha stem non-treated fibers(TSNTF),Typha stem combined treated fibers(TSCTF),brings to improve mechanical properties.This change in mechanical properties is affected by modifying the fiber structure showing alpha cellulose of(66.86%)and lignin ratio of(10.83%)with a crystallinity index of(58.47%).

Desired Dynamic Equation for Primary Frequency Modulation Control of Gas Turbines

Gas turbines play core roles in clean energy supply and the construction of comprehensive energy systems.The control performance of primary frequency modulation of gas turbines has a great impact on the frequency control of the power grid.However,there are some control difficulties in the primary frequency modulation control of gas turbines,such as the coupling effect of the fuel control loop and speed control loop,slow tracking speed,and so on.To relieve the abovementioned difficulties,a control strategy based on the desired dynamic equation proportional integral(DDE-PI)is proposed in this paper.Based on the parameter stability region,a parameter tuning procedure is summarized.Simulation is carried out to address the ease of use and simplicity of the proposed tuning method.Finally,DDE-PI is applied to the primary frequency modulation system of an MS6001B heavy-duty gas turbine.The simulation results indicate that the gas turbine with the proposed strategy can obtain the best control performance with a strong ability to deal with system uncertainties.The proposed method shows good engineering application potential.

拉美亟待破解转型困局

In 2023, Latin America was confronted with increased domestic and international challenges, resulting in a stronger public desire for change. New social ideologies are continuing to emerge, and transformation through reform has become a broad consensus. However, during the complicated reshaping of Latin America's political ecology, the swing of the political pendulum and the change of regimes are accelerating.

Dynamic Event-Triggered Control of Continuous-Time Systems With Random Impulses

In this paper,the networked control problem under event-triggered schemes is considered for a class of continuoustime linear systems with random impulses.In order to save communication costs and lighten communication burden,a dynamic event-triggered scheme whose threshold parameter is dynamically adjusted by a given evolutionary rule,is employed to manage the transmission of data packets.Moreover,the evolution of the threshold parameter only depends on the sampled measurement output,and hence eliminates the influence of impulsive signals on the event-triggered mechanism.Then,with the help of a stochastic analysis method and Lyapunov theory,the existence conditions of desired controller gains are received to guarantee the corresponding input-to-state stability of the addressed system.Furthermore,according to the semi-definite programming property,the desired controller gains are calculated by resorting to the solution of three linear matrix inequalities.In the end,the feasibility and validity of the developed control strategy are verified by a simulation example.

Inverse Design of Phononic Crystal with Desired Transmission via a Gradient-Descent Approach

We propose a general approach based on the gradient descent method to study the inverse problem,making it possible to reversely engineer the microscopic configurations of materials that exhibit desired macroscopic properties.Particularly,we demonstrate its application by identifying the microscopic configurations within any given frequency range to achieve transparent phonon transport through one-dimensional harmonic lattices.Furthermore,we obtain the phonon transmission in terms of normal modes and find that the key to achieving phonon transparency or phonon blocking state lies in the ratio of the mode amplitudes at ends.

An effective array beamforming scheme based on branch-and-bound algorithm

In this paper, we propose an effective full array and sparse array adaptive beamforming scheme that can be applied for multiple desired signals based on the branch-and-bound algorithm. Adaptive beamforming for the multiple desired signals is realized by the improved Capon method. At the same time,the sidelobe constraint is added to reduce the sidelobe level. To reduce the pointing errors of multiple desired signals, the array response phase of the desired signal is firstly optimized by using auxilary variables while keeping the response amplitude unchanged. The whole design is formulated as a convex optimization problem solved by the branch-and-bound algorithm. In addition,the beamformer weight vector is penalized with the modified reweighted l_(1)-norm to achieve sparsity. Theoretical analysis and simulation results show that the proposed algorithm has lower sidelobe level, higher SINR, and less pointing error than the stateof-the-art methods in the case of a single expected signal and multiple desired signals.

Fly Ash and Slag as Partial Replacement of Cement for the Synthesis of Low Carbon Cementitious Materials

Tailings known as solid waste are generated by the mining industry.The development of tailings as wet shotcrete aggregates has significant economic and environmental benefits.The fine particle size of the tailings results in a large consumption of traditional cement as a cementitious material and insignificant improvement in strength.Therefore,a composite cementitious system of cement and solid waste resources(fly ash and slag powder)is explored for this study.In this paper,the response surface methodology(RSM)is used to optimize the experimental design and a multivariate nonlinear response model with cement,fly ash and slag powder contents as variables are constructed,which can investigate the effect of the composite cementitious system on the strength of tailing wet shotcrete(TWSC).In addition,the information entropy(IE)is introduced and combined with the RSM to evaluate the composite cementitious system.Finally,the desirability function(DF)combined with RSM is used to optimize the composite cementitious system.The results show that the response model constructed in this paper has R^(2)=0.96 and P-value<0.01(the test result of the model is P-value<0.01),which indicates that the model has high reliability.The higher the content of slag powder and cement in the composite cementitious system,the higher the strength and comprehensive score of the TWSC.There is a critical value of fly ash content,which makes the maximum cementation of the composite cementing system.The optimal mix proportion of the composite cementitious system is obtained based on RSM-DF,which leads to the strength of TWSC at different curing time to achieve the expected index.

Extension of Goal-Directed Behavior Model for Post-Pandemic Korean Travel Intentions to Alternative Local Destinations: Perceived Risk and Knowledge

Since the outbreak of COVID-19,tourists have been increasingly concerned over various risks of international travel,while knowledge of the pandemic appears to vary significantly.In addition,as travel restrictions continue to impact adversely on international tourism,tourism efforts should be placed more on the domestic markets.Via structural equation modeling,this study unearthed different risk factors impacting Korean travelers’choices of alternative local destinations in the post-pandemic era.In addition,this study extended the goal-directed behavior framework with the acquisition of perceived risk and knowledge of COVID-19,which was proven to hold a sig-nificantly superior explanatory power of tourists’decisions of local alternatives over foreign countries during the COVID-19 pandemic.Furthermore,desire was found to play an imminent mediating role in the conceptual mod-el,maximizing the impact of perceived risk on travel intentions.Henceforth,this research offers meaningful the-oretical implication as thefirst empirical study to deepen the goal-directed behaviour framework with perceived risk and knowledge in the context of post-COVID-19 era.It also serves as insightful knowledge for Korean tour-ism authorities and practitioners to understand local tourists’decision-making processes and tailor effective recovery strategy for domestic tourism.

On Laozi’s View of Desire

Laozi’s concept of desire has rich ideological connotations,not only referring to reducing personal desires.Laozi’s concept of desire is based on“desire”as human nature,acknowledging the legitimacy and necessity of desire and demand.The rational criticism of“having desire”formed by“no desire”is the value pursuit of Laozi’s concept of desire.From both personal physical and mental aspects and social order,“no desire”plays an important guiding role.Nature is the essence of Laozi’s concept of desire,and being in harmony with nature is the best state of desire.Laozi’s concept of desire reveals a deep spirit of love,and the“ethics of love”highlights Laozi’s strong sense of care for the“other”and ethical attitude towards responsibility.Laozi’s contemplation of desire contains a strong humanistic spirit,with the aim of promoting the healthy and sustainable development of life and society.

Social Determinants of Social Zapping:Exploring Predictors of Planned Scheduled Social Events with Others

Social zapping has gained popularity as a term that refers to canceling plans or appointments at the last minute to attend other,supposedly more appealing events.This behavior resembles rapidly switching channels on a television,as individuals frequently jump between different social engagements.The present study examined potential behavioral trait predictors of social zapping,such as belongingness,self-esteem,sense of control,and meaningful existence among community residents ranging from 40 to 75 years of age(n=48).The study utilized simple linear regressions to identify potential predictors of social zapping,exploring how the four fundamental needs(belongingness,self-esteem,sense of control,and meaningful existence)might be linked.Results indicated that belongingness and self-esteem are significant predictors of social zapping tendencies.Additionally,an independent samples t-test was conducted to determine the relationship both older and younger adults have with the four fundamental needs as well as the role age plays in social zapping tendencies.Older adults exhibited a significant and more positive association with self-esteem,sense of control,and meaningful existence compared to individuals aged 39 and younger.Social zapping frequency was nonsignificant for both older adults and younger adults.Furthermore,a separate set of linear regression analyses were completed to determine how social desirability affects social zapping across age groups.Social desirability significantly predicted both self-esteem and meaningful existence.Overall,the present study builds on what is currently a new phenomenon in research and will provide new information on the relationship between age,social zapping,and behavioral traits.

基于Desirability函数法对米根霉发酵制备富马酸的多目标优化

以富马酸产量和生产速率为目标,通过正交实验考察了种龄、接种量、葡萄糖和尿素浓度对两者的影响,进一步利用基于响应曲面方法的Desirability函数确定了葡萄糖和尿素的最佳浓度。结果表明,最佳的种龄和接种量分别为36h和15%(v/v),葡萄糖和尿素的优化浓度为132.73和0.0586g/L,此时模型预测的富马酸产量和生产速率达到71.42g/L和0.804g/(l.h),Desirability的函数值高达0.966。该条件下在5L发酵罐水平上进行验证试验,经过88h的发酵最终生成富马酸66.5g/L,生产速率达到0.755g/(l.h),与未优化前相比,产量和生产速率分别提高了13.9%和15.8%,取得了理想的效果,实现了产量和生产速率的同时优化,为发酵法制备富马酸的工业化放大奠定了基础。

FKAOS:一种面向Agent需求工程方法

面向Agent需求工程重点研究软件系统的面向Agent的抽象组织形式 .本文提出一种新的面向Agent需求工程方法———FKAOS方法 .该方法作为较高抽象程度的以Agent为核心的软件系统描述方法能辅助用户和系统设计人员更好地分析和设计系统需求 .FKAOS方法通过引入FuzzyZ语言 ,扩展经典的KAOS方法 ,描述多Agent系统中的非确定需求问题 .FKAOS方法中的描述视图引入了KAOS方法的目标和责任视图 ,并添加了一些新的专门描述面向Agent的需求问题的视图和表 .本文重点介绍了FKAOS方法的基本元模型概念和相关的主要视图描述模型等内容 。

人机情感交互智能体及其在控制性能评价中的应用

在智能体的信念、愿望、意图模型基础上,提出了一个人机情感交互模型。根据隐马氏链模型的情感强度空间表达和个性OCC模型的结构框架,融合了一种人工心理应激模型的内涵,建立起一个刺激转移情感计算模型。详细给出了智能体的情感计算方法,并进一步将其加入到智能体的人机交互机制中,构造了人机交互学习模型,提出了人机交互目标完成程度指标及其计算和情感学习算法。以过程控制性能评价为应用实例,讨论了智能体人机情感交互模型的构建和相关算法,并针对具体的控制回路进行了仿真和分析,验证了所提出方法的可行性和有效性。

基于角色的多Agent的网格资源管理框架与分配策略

提出了一种适应计算网格分布动态环境的基于角色的多代理的资源管理框架,其核心的三种角色代理都采用BDI(Belief,Desire,Intention)代理模型,利用BDI代理的智能交互,进行协同合作以管理复杂的网格资源。还初步探讨了基于此框架的网格资源优化分配的策略和方法。

目录及其在分布式主题网关中的应用

介绍了目录的基本概念 ,分析了 L DAP、WHOIS+ +、CIP目录协议的主要特点 ,研究了国外主要的主题网关项目 (ISAAC、ROADS、DESIRE、Imesh Tool Kit)中目录协议的应用情况 ,指出目录协议在分布式索引、查询路由中起着的重要作用。

又见五台山剧场,山西,中国

又见五台山项目的创作是一次奇妙的体验,导演和建筑师的紧密合作,打破彼此之间的边界,从建筑主体向前广场延续出连续七折的墙体,宛若徐徐拉开的经折,巧妙地化解了大型建筑体量对自然环境的压迫感,形成没有边际的建筑。

翻译文学的本土化策略探析——以The World’s Desire两个译本解读为例

目标语意识形态和诗学是影响翻译文学本土化的两个重要操控因素。林纾、周作人对英国冒险小说家哈格德The World’s Desire的翻译有着诸多差异,体现了意识形态和诗学在翻译本土化过程中所发挥的作用。这两个译本折射了翻译文学在中国的传播演变过程,也对中国文学翻译出口有一定的借鉴意义。

Analysis of distance headway

By means of the relationship between speed and distance headway, this paperattempts to directly determine the road capacity based on a new concept. At first it makes acomprehensive analysis of distance headway, including safe distance headway and desired one. Theformer is decided by the demand for the degree of safety, and the latter depends on the motorists'behavior, i.e. the model of traffic flow. Both of them are functions of speed. According to thecharacteristics of their curves, we can find a crossing point that is the capacity of a roadsegment. This capacity represents the maximum flow rate meeting the minimum safety requirement.

New Adaptive Cruise Control Method

A new adaptive cruise control (ACC) method based on the desired safety headway distance is investigated for improving the vehicle traffic safety at high speed by regulating the additional throttle opening and braking torque of driving wheels only. The selection of headway distance sensors, the determination of desired safety headway distance and desired deceleration are elaborated. The ACC flowchart and simulation, as well as signal misinformation and its resolutions are described. The simulation proves that the new ACC method is simpler and feasible. The new method is easily integrated ACC with ABS/ASR to form an organic ABS/ASR/ACC system.