Attosecond ionization time delays in strong-field physics

Electronic processes within atoms and molecules reside on the timescale of attoseconds. Recent advances in the laserbased pump-probe interrogation techniques have made possible the temporal resolution of ultrafast electronic processes on the attosecond timescale, including photoionization and tunneling ionization. These interrogation techniques include the attosecond streak camera, the reconstruction of attosecond beating by interference of two-photon transitions, and the attoclock. While the former two are usually employed to study photoionization processes, the latter is typically used to investigate tunneling ionization. In this review, we briefly overview these timing techniques towards an attosecond temporal resolution of ionization processes in atoms and molecules under intense laser fields. In particular, we review the backpropagation method, which is a novel hybrid quantum-classical approach towards the full characterization of tunneling ionization dynamics. Continued advances in the interrogation techniques promise to pave the pathway towards the exploration of ever faster dynamical processes on an ever shorter timescale.

Adaptive predictor-based control for a helicopter system with input delays:Design and experiments

In this paper,we consider a 2-degrees-of-freedom(DOF)helicopter system subject to long input delays and uncertain system parameters.To address the challenges including unknown system parameters and input delays in control design,we develop an adaptive predictor-feedback control law to achieve trajectory tracking.Stability of the closed-loop system is further established,where the tracking errors are shown to converge towards zero.Through simulation and experiments on the helicopter system,we illustrate that tracking of a desired trajectory is achieved with the proposed control scheme.

Sliding Mode Control for Recurrent Neural Networks With Time-Varying Delays and Impulsive Effects

Dear Editor,This letter studies the problem of sliding mode control(SMC)design for recurrent neural networks(RNNs)with impulsive disturbances and time-varying transmission delays.To this end,an appropriate integral sliding surface function and SMC law are adopted for use under impulsive disturbances and time-varying delays.

Position Measurement Based Slave Torque Feedback Control for Teleoperation Systems With Time-Varying Communication Delays

Bilateral teleoperation system is referred to as a promising technology to extend human actions and intelligence to manipulating objects remotely.For the tracking control of teleoperation systems,velocity measurements are necessary to provide feedback information.However,due to hardware technology and cost constraints,the velocity measurements are not always available.In addition,the time-varying communication delay makes it challenging to achieve tracking task.This paper provides a solution to the issue of real-time tracking for teleoperation systems,subjected to unavailable velocity signals and time-varying communication delays.In order to estimate the velocity information,immersion and invariance(I&I)technique is employed to develop an exponential stability velocity observer.For the proposed velocity observer,a linear relationship between position and observation state is constructed,through which the need of solving partial differential and certain integral equations can be avoided.Meanwhile,the mean value theorem is exploited to separate the observation error terms,and hence,all functions in our observer can be analytically expressed.With the estimated velocity information,a slave-torque feedback control law is presented.A novel Lyapunov-Krasovskii functional is constructed to establish asymptotic tracking conditions.In particular,the relationship between the controller design parameters and the allowable maximum delay values is provided.Finally,simulation and experimental results reveal that the proposed velocity observer and controller can guarantee that the observation errors and tracking error converge to zero.

Hopf bifurcation and phase synchronization in memristor-coupled Hindmarsh–Rose and FitzHugh–Nagumo neurons with two time delays

A memristor-coupled heterogenous neural network consisting of two-dimensional(2D)FitzHugh–Nagumo(FHN)and Hindmarsh–Rose(HR)neurons with two time delays is established.Taking the time delays as the control parameters,the existence of Hopf bifurcation near the stable equilibrium point in four cases is derived theoretically,and the validity of the Hopf bifurcation condition is verified by numerical analysis.The results show that the two time delays can make the stable equilibrium point unstable,thus leading to periodic oscillations induced by Hopf bifurcation.Furthermore,the time delays in FHN and HR neurons have different effects on the firing activity of neural network.Complex firing patterns,such as quiescent state,chaotic spiking,and periodic spiking can be induced by the time delay in FHN neuron,while the neural network only exhibits quiescent state and periodic spiking with the change of the time delay in HR neuron.Especially,phase synchronization between the heterogeneous neurons is explored,and the results show that the time delay in HR neurons has a greater effect on blocking the synchronization than the time delay in FHN neuron.Finally,the theoretical analysis is verified by circuit simulations.

Cyclic-Pursuit-Based Circular Formation Control of Mobile Agents with Limited Communication Ranges and Communication Delays

This article addresses the circular formation control problem of a multi-agent system moving on a circle in the presence of limited communication ranges and communication delays.To minimize the number of communication links,a novel distributed controller based on a cyclic pursuit strategy is developed in which each agent needs only its leading neighbour’s information.In contrast to existing works,we propose a set of new potential functions to deal with heterogeneous communication ranges and communication delays simultaneously.A new framework based on the admissible upper bound of the formation error is established so that both connectivity maintenance and order preservation can be achieved at the same time.It is shown that the multi-agent system can be driven to the desired circular formation as time goes to infinity under the proposed controller.Finally,the effectiveness of the proposed method is illustrated by some simulation examples.

Cascading Delays for the High-Speed Rail Network Under Different Emergencies:A Double Layer Network Approach

High-speed rail(HSR) has formed a networked operational scale in China. Any internal or external disturbance may deviate trains’ operation from the planned schedules, resulting in primary delays or even cascading delays on a network scale. Studying the delay propagation mechanism could help to improve the timetable resilience in the planning stage and realize cooperative rescheduling for dispatchers. To quickly and effectively predict the spatial-temporal range of cascading delays, this paper proposes a max-plus algebra based delay propagation model considering trains’ operation strategy and the systems’ constraints. A double-layer network based breadth-first search algorithm based on the constraint network and the timetable network is further proposed to solve the delay propagation process for different kinds of emergencies. The proposed model could deal with the delay propagation problem when emergencies occur in sections or stations and is suitable for static emergencies and dynamic emergencies. Case studies show that the proposed algorithm can significantly improve the computational efficiency of the large-scale HSR network. Moreover, the real operational data of China HSR is adopted to verify the proposed model, and the results show that the cascading delays can be timely and accurately inferred, and the delay propagation characteristics under three kinds of emergencies are unfolded.

Lyapunov-Based Output Containment Control of Heterogeneous Multi-Agent Systems With Markovian Switching Topologies and Distributed Delays

This paper considers the mean square output containment control problem for heterogeneous multi-agent systems(MASs)with randomly switching topologies and nonuniform distributed delays.By modeling the switching topologies as a continuous-time Markov process and taking the distributed delays into consideration,a novel distributed containment observer is proposed to estimate the convex hull spanned by the leaders'states.A novel distributed output feedback containment controller is then designed without using the prior knowledge of distributed delays.By constructing a novel switching Lyapunov functional,the output containment control problem is then solved in the sense of mean square under an easily-verifiable sufficient condition.Finally,two numerical examples are given to show the effectiveness of the proposed controller.

Investigation on maternal mortality in Southeast Asia,Europe and Africa using three delays model

Background:Maternal mortality is a prevalent issue in healthcare provision worldwide.It is particularly common in developing and underdeveloped countries,where maternal deaths during childbirth or pregnancy occur frequently.Various internal and external factors contribute to the high maternal mortality rate in specific regions.One model,known as the three delays model approach,examines three distinct causes that contribute to this problem.The first delay is the lack of awareness in seeking timely healthcare,the second delay involves obstacles in reaching healthcare facilities on time,and the third delay relates to poor or inadequate healthcare provision in tertiary care facilities.These delays are responsible for the elevated maternal mortality rates,with the prevalence of each delay varying across regions.Objective:The objective of this literature review is to examine and critically evaluate existing literature on perceptions and investigations regarding maternal mortality in Southeast Asia,Europe and Africa,utilizing the three delays model approach as a categorization framework.Method:This literature review followed BEME guide No.3.A total of 18 articles were included in the sample after conducting a thorough search of various databases and search engines.A Prisma flowchart was created,and the articles were critically appraised.Results:A total of 18 articles focusing on different regions were analyzed.The findings revealed that in countries of Southeast Asia,the primary cause of maternal mortality is the first delay,which refers to the lack of awareness in seeking medical care.On the other hand,in Africa and other European countries,the second and third delays are more prominently associated with maternal mortality.Conclusion:Inadequate care is one of the major causes of maternal mortality in majority of regions acrossthe globe.Multiple factors can hinder access to appropriate healthcare.The three delays model plays a significant role in the higher maternal mortality rate.By raising awareness among women and their families about the importance of seeking healthcare,the risk of fatality can be reduced.Similarly,in developing regions,it is crucial to ensure that healthcare facilities are easily accessible and provide high-quality emergency obstetric care to meet the needs of pregnant women in critical situations.

中国西南地区电解锰渣特性分析及影响因素研究

电解锰行业发展面临的困境之一是锰渣的处理处置方法。为探索绿色低碳的锰渣无害化处理技术,选取中国5家典型电解锰企业新、旧电解锰渣,通过其理化特性及浸出毒性分析,研究堆存条件、时间及工艺参数等因素对不同企业锰渣特性的影响。结果显示:不同企业的新、旧锰渣平均质量含水率相差最大时均达19%以上,浸出液pH值最高分别相差0.95、1.45,不同企业新鲜锰渣的SiO_(2)和Al_(2)O_(3)平均质量分数最大相差分别为43.18%、146.25%,且可溶性盐质量分数均超过10%,未达到填埋入场标准。锰渣中石膏和石英的质量分数随堆存条件和时间发生不同的变化。企业C在堆存过程中石膏和石英的质量分数在增加,而企业E锰渣中烧石膏质量分数在增加,石英质量分数在减少。历史锰渣浸出液中Mn^(2+)和氨氮(NH_(4)^(+)N)的质量浓度较高,分别超过GB/T 8978—1996一级排放标准限值的65.92~935.00倍和2.56~63.80倍,表明长期堆存的锰渣仍存在较大的环境污染风险。不同地区企业的锰渣应通过无害化处理与资源化利用来降低其环境污染风险,须根据化学成分、理化性质不同选择合适的资源化方式。

Hopf Bifurcation of Nonresident Computer Virus Model with Age Structure and Two Delays Effects

This paper constructed and studied a nonresident computer virus model with age structure and two delays effects. The non-negativity and boundedness of the solution of the model have been discussed, and then gave the basic regeneration number, and obtained the conditions for the existence and the stability of the virus-free equilibrium and the computer virus equilibrium. Theoretical analysis shows the conditions under which the model undergoes Hopf bifurcation in three different cases. The numerical examples are provided to demonstrate the theoretical results.

Perception-Based Assessment of the Factors Causing Delays in Construction Projects

Construction delay is a widespread issue in the construction industry of developing countries, and Nepal is no exception. These delays extend project durations and lead to cost overruns and disputes among stakeholders. To address this problem, this study aimed to identify and analyze the significant factors that contribute to construction project delays in Nepal. To gather data, a well-structured questionnaire was developed and administered to a sample of 100 participants, including contractors, consultants, and civil engineers. Various statistical tests were conducted to ensure the data’s integrity and consistency, such as reliability assessments and factor analyses. The findings of the study highlighted multiple factors contributing to delays in construction projects such as inadequate design, poor communication, and coordination among stakeholders, insufficient experience and planning by contractors, delays in material delivery and testing, labor-related problems including shortages and low qualifications, and external factors like regulatory changes and unforeseen circumstances. By identifying these major causes of construction project delays, this study presented insightful information that can contribute to the analysis and evaluation of project performance.

A Study of Radiation-Induced Instability for the Gene Locus Associated with Intellectual Disorders or Developmental Delays

Multiplex Ligation-Dependent Probe Amplification (MLPA) was used to study the integrity of the chromosomes for two WIL2-derived lymphoblastoid cell lines (TK6 and WTK1) in the presence and absence of ionizing radiation. WTK1 cells contain a p53 mutation, whereas the TK6 cell line has the native p53 tumor-suppressor gene. Each cell line was isolated pre- and post-irradiation (2 and 3 Gy) and analyzed by MLPA. Using probes that target specific regions on chromosomes associated with a distinct subset of microdeletions and microduplications either established or thought to be responsible for intellectual disability or developmental delay, we have demonstrated that WTK1 and TK6 are not impacted in the same way by irradiation. Instead, each cell line presents its own unique MLPA profile. The most notable differences are the appearance of nine unique probe signals only seen in WTK1 cells. These results are important in the study of how different cell lines can be affected in significantly different ways depending on the presence or absence of wild type p53.

我国黑水虻研究现状与展望——基于CiteSpace的可视化分析

文章检索中文文献和国内机构中黑水虻的相关文献,运用CiteSpace可视化分析软件对2000—2023年已发表的黑水虻相关中、英文文献共670篇进行可视化分析。根据对文献的发文量、发表时间、作者、研究机构、关键词的分析,结果显示:黑水虻相关文献发文时间集中在2016—2022年期间;国内的机构合作的群体较多,基本集中在西北地区;黑水虻的关键词分析主要集中在抗菌肽、资源化利用、血清生化指标、黑水虻幼虫、亮斑扁角水虻、幼虫、波长、产业化养殖这8个方面。综合以上分析结果,未来黑水虻的研究方向集中在黑水虻抗菌肽的推广应用、黑水虻资源产业化的运用、黑水虻养殖技术的升级应用、黑水虻幼虫饲料的开发应用这三个方面。

有机硅高沸物催化裂解技术进展

催化裂解技术可高效低能耗地资源化处理利用有机硅高沸物,有机硅高沸物催化裂解技术根据所用催化剂不同可分为氯化铝基催化裂解技术、有机胺基催化裂解技术、钯磷配位化合物基催化裂解技术、磷酸盐基催化裂解技术、过渡金属及其化合物基催化裂解技术、分子筛和活性炭基催化裂解技术等。对这些技术的特点、发展现状和趋势进行了研究,为有效利用这些技术对有机硅高沸物通过催化裂解实现资源化处理利用提供技术支持。研究表明,有机胺基催化裂解技术相对其他技术具有其他技术无可比拟的技术优势,是未来有机硅高沸物催化裂解技术发展的一个趋势和热点。

二次铝灰无害化处理和资源化利用研究进展

二次铝灰是铝熔渣经提取金属铝后得到的固体废弃物,含有氮化铝以及盐类精炼剂,二次铝灰具有污染和资源的双重属性,长期堆存会对环境构成威胁,而夹杂其中的铝化合物可用于二次回收利用,缓解环境危机。目前,二次铝灰的回收利用方法主要包括湿法冶金和火法冶金,湿法冶金主要是将二次铝灰进行溶解,提取里面的铝元素制备氧化铝、聚合氯化铝等;火法冶金主要是在高温条件下煅烧,制备微晶玻璃、耐火材料等。本文总结了二次铝灰的危害,概述了二次铝灰的无害化处理和资源化利用的现状,以期提高二次铝灰的资源化利用效率,降低二次铝灰对环境的污染。

无垫料病死畜禽无害化处理设备设计思路

简要介绍了福建省病死畜禽无害化处理主要方式,提出无垫料病死畜禽无害化处理的工艺流程,介绍了无害化处理设备结构设计思路和样机试验验证情况。

焚烧飞灰水热合成托贝莫来石过程中重金属的固化特性

城市生活垃圾焚烧飞灰的环境安全利用处置已成为当前环境管理部门和行业部门亟待解决的问题。为降低焚烧飞灰中重金属对环境的潜在风险,以水洗飞灰为原料水热合成托贝莫来石,探讨Ca与(Si+Al)的摩尔比[以Ca/(Si+Al)表示]对水热产物的晶相组成、微观形貌和表面官能团的影响,研究水热过程中重金属(Hg、Ni、Pb、Zn和Cr)的浸出浓度、浸出率、液相迁移率、形态分布和环境风险的变化。结果表明:Ca/(Si+Al)对水热产物的类型具有重要影响,Ca/(Si+Al)的增加有利于抑制沸石类结构的生成,促进托贝莫来石的形成。随着托贝莫来石的形成,水热产物中5种重金属的毒性浸出浓度和浸出率逐渐降低,相较于水洗飞灰,在最佳比例为1.10的条件下水热产物中重金属的浸出浓度分别下降99.5%、99.0%、99.4%、88.9%和63.7%,浸出率低至0.25%、0.08%、0.01%、0.01%和2.73%,同时重金属向液相的迁移率仅为1.41%、4.28%、0.29%、0.05%和0%,表明大部分重金属均稳定地存在于固相产物中,而不是迁移至水热液中。这归因于托贝莫来石的形成增加了5种重金属残渣态的占比,降低了重金属的迁移性。风险评价指数(risk assesssment code,RAC)结果显示,最佳比例条件下水热产物中5种重金属的RAC均低于10%,达到环境低风险水平。综上,水热合成托贝莫来石是一种稳定焚烧飞灰中重金属很有前景的方法,为富含重金属的危险废物的安全处置和回收利用提供了一种可行的替代方案。

某金矿氰化尾渣氧化焙烧无害化处置及机理研究

针对某金矿氰化尾渣络合氰化物占比极高的特点,采用氧化焙烧工艺处理氰化尾渣.试验结果表明,将氰化尾渣样品在焙烧温度550℃,焙烧时间30 min,O_(2)体积分数20%,总气量600 mL/min条件下进行氧化焙烧试验,可将氰化尾渣中的总氰化物含量降至检出限0.04 mg/kg以下,同时硫元素保留率达到82.22%.针对相应的铁氰络合物K_(4)Fe(CN)_(6)进行热重分析,结果表明K4Fe(CN)_(6)首先被氧化为KCNO,进而氧化为K_(2)CO_(3),两阶段均伴随有CO_(2),CO,NO_(2),NO等气态产物生成,且第一阶段伴随有副反应发生.该工艺不仅可以将氰化尾渣中的氰化物特别是络合氰化物有效分解,同时可保证尾渣中硫元素不易被氧化,大幅减少后续烟气脱硫成本,具有广泛的应用前景.

利用响应面法优化废弃钻井液破胶

针对废弃水基钻井液破胶难、回用难且存在二次污染等问题,开展废弃水基钻井液破胶过程的优化。基于对废弃水基钻井液的性能分析,采用单因素试验对复合破胶剂破胶过程中各因素的影响规律进行研究,借助响应面法对破胶过程的显著性影响因素进行深度优化。结果表明:废弃水基钻井液的工作性能无法满足油田作业区规定的指标要求,必须对其进行破胶回用处理;当破胶剂加入量为3.97 kg/m^(3)废弃水基钻井液,反应温度为51℃,搅拌速度为419 r/min时,废弃水基钻井液破胶出水率的预测最优值(体积分数)可达62.37%,经t检验,预测最优值和实验验证值之间不存在显著差异。该研究可为深层复杂钻井液的无害化处理提供准确可靠的理论依据和数据来源。