Remaining Useful Life Model and Assessment of Mechanical Products: A Brief Review and a Note on the State Space Model Method

The remaining useful life(RUL) prediction of mechanical products has been widely studied for online system performance reliability, device remanufacturing, and product safety(safety awareness and safety improvement). These studies incorporated many di erent models, algorithms, and techniques for modeling and assessment. In this paper, methods of RUL assessment are summarized and expounded upon using two major methods: physics model based and data driven based methods. The advantages and disadvantages of each of these methods are deliberated and compared as well. Due to the intricacy of failure mechanism in system, and di culty in physics degradation observation, RUL assessment based on observations of performance variables turns into a science in evaluating the degradation. A modeling method from control systems, the state space model(SSM), as a first order hidden Markov, is presented. In the context of non-linear and non-Gaussian systems, the SSM methodology is capable of performing remaining life assessment by using Bayesian estimation(sequential Monte Carlo). Being e ective for non-linear and non-Gaussian dynamics, the methodology can perform the assessment recursively online for applications in CBM(condition based maintenance), PHM(prognostics and health management), remanufacturing, and system performance reliability. Finally, the discussion raises concerns regarding online sensing data for SSM modeling and assessment of RUL.

Space Life Science of China in 2013

In the past two years, space life science research in China is characterized by a wide area of basic researches for providing foundation for the future China Space Station. The effect of microgravity and radiation was further studied from physiology phenomena to the level of bio-molecule mechanisms. Chinese space life science is maturing in a new era of comprehensive development.Here, we review and summarize researches on space life sciences which were contributed by Chinese scientists.

Space Life Science of China

In the past two years,China’s space life science has made great progress.Space biomedical and life science programs have carried out ground-based research for the first batch of projects,and are preparing to carry out space-based experiments along with the construction of China’s space station.And space life science payload of the space station completed the development of positive samples.Thus,with the development of lunar exploration and Mars exploration projects,astrobiology research has also made a lot of basic achievements.On the basis of summarizing the development of space life science in China,this paper mainly introduces the important progress of payload technology and life science research.

Space Life Science in China

With the further advancement of China’s major manned spaceflight project,the national space laboratory was successfully built.China has also made considerable progress and breakthroughs in the field of space life sciences.This paper reviews the related biological effects under space flight conditions,mainly including epigenetic effects,skeleton remodeling and peripheral body fluid circulation effects,as well as the research and application of space life science related biotechnology in the field of microbial culture and biological regeneration life support system.

Remaining Useful Life Prediction for Aero-Engines Combining Sate Space Model and KF Algorithm

The key to failure prevention for aero-engine lies in performance prediction and the exhaust gas temperature margin(EGTM)is used as the most important degradation parameter to obtain the operating performance of the aero-engine.Because of the complex environment interference,EGTM always has strong randomness,and the state space based degradation model can identify the noisy observation from the true degradation state,which is more close to the actual situations.Therefore,a state space model based on EGTM is established to describe the degradation path and predict the remaining useful life(RUL).As one of the most effective methods for both linear state estimation and parameter estimation,Kalman filter(KF)is applied.Firstly,with EGTM degradation data,state space model approach is used to set up a state space model for aero-engine.Secondly,RUL of aero-engine is analyzed,and expected RUL and distribution of RUL are determined.Finally,the sate space model and KF algorithm are applied to an example of CFM-56aero-engine.The expected RUL is predicted,and corresponding probability density distribution(PDF)and cumulative distribution function(CDF)are given.The result indicates that the accuracy of RUL prediction reaches 7.76%ahead 580 flight cycles(FC),which is more accurate than linear regression,and therefore shows the validity and rationality of the proposed method.

基于CiteSpace的老年人生活空间研究的可视化分析

目的分析近20年老年人生活空间研究现状、研究热点及前沿。方法以“老年人和生活空间”为主题,系统检索2000年1月1日-2023年6月30日Web of Science核心合集数据库发表的有关老年人生活空间的相关文献,使用CiteSpace 6.1.R6软件对文献的发表时间、作者、国家、机构和关键词进行可视化分析。结果最终共纳入291篇文献,整体发文量呈上升态势;发文量最多的国家是美国;发文量最多的机构是Univ Jyvaskyla(于韦斯屈莱大学);研究热点主要集中在老年人生活空间流行病学调查、生活空间的评估、老年人生活空间受限的相关影响因素及不良结局。结论近年来老年人的生活空间问题受到持续关注,我国未来应加强与国外在生活空间研究领域的合作与交流,提高我国该领域的研究水平。

Space Life Science of China in 2015

With the human space exploration activities,space life science is an emerging interdisciplinary and it covers a wide range of research.Based on our country's manned space station and recoverable satellite science experimental platform,the development of space life science research is very important to acquire new knowledge or new innovation in technology,to give further services to the human space exploration activities,to improve the national economic and social development.Based on present situation,both theoretical and applied researches were continuously performed in2015.Here,we review and summarize the researches on space life sciences which were contributed by Chinese scientists.

Progress Report of Space Life Science in China

In the past two years,space life sciences research in China is characterized by a tendency toward integration of scientific and engineering resources in preparing and implementing advanced space programs.In the field of operational medicine,we carried out an international cooperated Head-Down Bed Rest(HDBR) experiment and investigated the effects of Chinese herbs compounds on astronaut's physiological functions.The effect of microgravity and its mechanisms were further studied from the level of physiology and biology.At the same time,state-level platform for ground and space experiment was established.

Predictive Maintenance of Manned Spacecraft Through Remaining Useful Life Estimation Technique

Manned spacecraft pose challenges in terms of extremely high safety and reliability, and with the growth of system complexity and longer on-orbit operation time, the traditional management mode, such as monitoring the threshold of parameter passively, is difficult to meet the required safety standards. Predictive maintenance, which analyzes the system heath trend and estimates remaining useful life(RUL) to establish maintenance strategies ahead of time before failure occurs, is a new mode to approach maintenance tasks. Here, a predictive maintenance strategy for complex manned spacecraft is proposed based on the remaining useful life estimation technique. Firstly, a health index is established based on an abundance of telemetry data, reflecting the system's current health state. Secondly, we map the health index to the remaining useful life through system degradation modelling, taking into consideration both the system's stochastic deterioration and uncertainty. The maintenance and management strategies are then made based on the calculated distribution of RUL time. Finally, a case study on Chinese space station energy system predictive maintenance is presented.

Space Life Science of China

With the human space exploration activities, space life science is an emerging interdiscipline,which covers a wide range of researches. Based on our country's manned space station and recoverable satellite science experimental platform, the development of space life science research is very important to acquire new knowledge or new technological innovation, to give further services to the human space exploration activities,to improve the national economic and social development. Both ground-based and flight applied studies were continuously performed in the previous 2 years. Here, we review and summarize the researches on space life sciences contributed by Chinese scientists.

Recent Progress in Space Science and Applications on Chinese Space Station in 2022–2024

Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as space life science and biotechnology,space materials science,microgravity fundamental physics,fluid physics,combustion science,space new technologies,and applications.In this review,we introduce the progress of CSS development and provide an overview of the research conducted in Chinese Space Station and the recent scientific findings in several typical research fields.Such compelling findings mainly concern the rapid solidification of ultra-high temperature alloy melts,dynamics of fluid transport in space,gravity scaling law of boiling heat transfer,vibration fluidization phenomenon of particulate matter,cold atom interferometer technology under high microgravity and related equivalence principle testing,the full life cycle of rice under microgravity and so forth.Furthermore,the planned scientific research and corresponding prospects of Chinese space station in the next few years are presented.

Life Space Assessment in Older Women Undergoing Non-Surgical Treatment for Urinary Incontinence

Objective: Urinary incontinence (UI) impacts all aspects of life activities. This study aims to characterize change in mobility within the community utilizing the Life Space Assessment (LSA) questionnaire in women undergoing non-surgical UI treatment. Methods: This prospective cohort study, performed from July 2007 to March 2009, followed women seeking non-surgical UI treatment from an outpatient tertiary-care clinic and assessed their mobility and symptoms using LSA, Urogenital Distress Inventory (UDI-6), and Incontinence Impact Questionnaire (IIQ-7) at baseline and 2, 6, and 12 months post-treatment. Estimated Percent Improvement (EPI) and Patient Satisfaction Question (PSQ) were obtained post-treatment. The women were treated with multi-component behavioral and/or pharmacologic therapies, and we hypothesized that LSA would improve with treatment. Repeated measures analysis with Tukey’s HSD and backwards selection linear regression model were performed. Results: 70 ambulatory, community-dwelling women, aged 65 years or older, seeking non-surgical care for UI were recruited. LSA score decreased from baseline to 2 months (mean ± SD;63 ± 29 to 56 ± 28, p < 0.001) and was sustained at 6 and 12 months (54 ± 28, 54 ± 28). UDI scores improved from 36 ± 23 to 25 ± 24, p < 0.001, at 2 months, and improvement persisted at 6 and 12 months (22 ± 22, 21 ± 24). Improvements in UDI and patient perceived improvement in UI were not associated with LSA change. Age, race, and depression impacted LSA, which decreased 1-point for each additional year of age (p = 0.004), 6-points for each point higher on the Geriatric Depression Scale (GDS) (p = 0.002), and 6-point for African American race (p = 0.048). Conclusion: Decreased mobility represented by LSA was related to age, depression, and race, but not UI symptom improvement.

Identity of Urban Spaces: Assessment and Evaluation

As a major symbol of civilization,the city was built by man for his security and comfort.It is not only a settlement,but also an urban development which has been identified with the spirit that has been breathed into the community.Urban identity which is also known as collective identity,has gained meaning through the content of objective manifestation and the creation of flashbacks,citizens’memories and mental associations.That is what makes urban dwellers become citizens.Although the identity of the city is a result of civic culture,it still has an influence on the process of citizenship and can also be a reason for developing criteria related to the participation and assessment of its inhabitants.According to the view that identity is a set of traits and characteristics that distinguishes the dignity of a person and a society from other individuals and communities,a city becomes characterized and independent by adhering to these criteria.Despite the importance of identity as one of the richest qualitative aspects of urban life that gives meaning and fulfilment to the human quiddity,this complicated and expanded concept has still not been seriously considered,especially in relation to urban spaces.In fact,identity in architecture and urban spaces has recently diminished,since the main focus lies on building spaces for optimized profit and not for high quality living areas.In this research paper,parameters affecting urban identity are evaluated,and strategies and guidelines to promote these parameters are finally presented.

Extraterrestrial Life in the Thermosphere: Plasmas, UAP, Pre-Life, Fourth State of Matter

“Plasmas” up to a kilometer in size and behaving similarly to multicellular organisms have been filmed on 10 separate NASA space shuttle missions, over 200 miles above Earth within the thermosphere. These self-illuminated “plasmas” are attracted to and may “feed on” electromagnetic radiation. They have different morphologies: 1) cone, 2) cloud, 3) donut, 4) spherical-cylindrical;and have been filmed flying towards and descending from the thermosphere into thunderstorms;congregating by the hundreds and interacting with satellites generating electromagnetic activity;approaching the Space Shuttles. Computerized analysis of flight path trajectories documents these plasmas travel at different velocities from different directions and change their angle of trajectory making 45°, 90°, and 180° shifts and follow each other. They’ve been filmed accelerating, slowing down, stopping, congregating, engaging in “hunter-predatory” behavior and intersecting plasmas leaving a plasma dust trail in their wake. Similar life-like behaviors have been demonstrated by plasmas created experimentally. “Plasmas” may have been photographed in the 1940s by WWII pilots (identified as “Foo fighters”);repeatedly observed and filmed by astronauts and military pilots and classified as Unidentified Aerial—Anomalous Phenomenon. Plasmas are not biological but may represent a form of pre-life that via the incorporation of elements common in space, could result in the synthesis of RNA. Plasmas constitute a fourth state of matter, are attracted to electromagnetic activity, and when observed in the lower atmosphere likely account for many of the UFO-UAP sightings over the centuries.

“Second Life”中的图书馆2.0

文章简要介绍了Second life的应用情况,并主要对在Second life中建立和延伸图书馆服务的意义和国外的应用发展状况进行了阐述。

城市公园绿地碳汇能力影响因素的网状荟萃(Meta)分析

[目的]城市公园绿地为人类提供与健康福祉密切相关的多种生态系统服务,具备生态、社会、经济多重效益,其碳汇能力受多个影响因素控制。综合评估多个因素对城市公园绿地碳汇能力的影响,以此探讨低碳城市公园设计策略的最优解。[方法]以“碳汇”“公园”等为关键词进行文献检索,使用网状荟萃(Meta)分析对城市公园绿地碳汇能力的不同影响因素进行系统性定量评估,并根据其影响大小进行分类统计。通过基于网络证据图的影响因素重要性评估、基于联赛表的相对影响能力分析、基于累积排序概率曲线下面积(surface under the cumulative ranking curves,SUCRA)图的综合影响能力分析,综合评估不同影响因素对城市公园绿地碳汇能力的实际作用,并结合亚组分析和漏斗图评估研究样本的异质性、误差及偏倚。[结果]共检索952篇文献,纳入50篇有效文献,提取34个城市公园绿地碳汇能力的关键影响因素,划分为设计形态、生境组成、种植方式、管护形式、外部环境五大聚类。其中,设计形态和管护形式对于提升城市公园绿地碳汇能力效果稳定,适用性较强,是提升碳汇能力的基础因素;生境组成和种植方式在特定场景下提升碳汇能力效果显著,但受场地特征限制;外部环境对城市公园绿地碳汇能力的直接影响较弱。[结论]城市公园绿地碳汇能力受多种因素共同作用,在以碳汇为导向的设计方案中,应优先考虑优化设计形态和管护形式,根据场地实际条件灵活调配不同的生境组成和种植方式,并适当考虑外部环境的影响。

内在能力在社区老年人外环境与生活空间移动性间的中介效应研究

目的探讨内在能力在社区老年人外环境与生活空间移动性间的中介效应,为制订针对性干预措施提供参考。方法2024年4-6月,采用整群随机抽样法选取延吉市12个社区的517名老年人作为研究对象,并采用一般资料调查表、生活空间评价量表、内在能力评估工具(康奈尔医学指数、简易精神状态评估量表、巴氏指数评定量表、简易营养评价精法、正性负性情绪量表)、外环境测评工具进行调查。结果社区老年人生活空间移动性受限发生率为61.51%,得分为(54.07±30.38)分,内在能力得分为(194.58±27.73)分,外环境得分为(80.60±11.69)分;生活空间移动性与外环境、内在能力呈正相关,外环境与内在能力呈正相关(均P<0.05);外环境可正向影响生活空间移动性,内在能力在外环境和生活空间移动性之间起部分中介作用,中介效应为0.240,占总效应的43.40%。结论社区老年人生活空间移动性处于中等偏低水平,内在能力在外环境和生活空间移动性之间发挥部分中介效应。社区医护人员可将内在能力作为靶点进行干预,结合外环境特点基于内在能力发展的不同时期因地制宜地制订个性化方案,促进老年人社会参与。

校园科学场馆空间:“生活·实践”教育沉浸式体验的新阵地

为了探讨校园科学场馆空间在“生活·实践”教育中的重要性,以及将其打造成沉浸式体验的新阵地,通过对校园中科学场馆空间的特点、优势以及当前教育需求的分析,提出了一系列具体的策略和方法,以实现“生活·实践”教育在校园科学场馆空间中的沉浸式体验,并希望以此促进学生的全面发展。

Remaining Useful Life Prediction of Rolling Element Bearings Based on Different Degradation Stages and Particle Filter

A method is proposed to improve the accuracy of remaining useful life prediction for rolling element bearings,based on a state space model(SSM)with different degradation stages and a particle filter.The model is improved by a method based on the Paris formula and the Foreman formula allowing the establishment of different degradation stages.The remaining useful life of rolling element bearings can be predicted by the adjusted model with inputs of physical data and operating status information.The late operating trend is predicted by the use of the particle filter algorithm.The rolling bearing full life experimental data validate the proposed method.Further,the prediction result is compared with the single SSM and the Gamma model,and the results indicate that the predicted accuracy of the proposed method is higher with better practicability.

Robust Remaining Useful Life Estimation Based on an Improved Unscented Kalman Filtering Method

In the Prognostics and Health Management(PHM),remaining useful life(RUL)is very important and utilized to ensure the reliability and safety of the operation of complex mechanical systems.Recently,unscented Kalman filtering(UKF)has been applied widely in the RUL estimation.For a degradation system,the relationship between its monitored measurements and its degradation states is assumed to be nonlinear in the conventional UKF.However,in some special degradation systems,their monitored measurements have a linear relation with their degradation states.For these special problems,it may bring estimation errors to use the UKF method directly.Besides,many uncertain factors can result in the fluctuations of the estimated results,which may have a bad influence on the RUL estimation method.As a result,a robust RUL estimation approach is proposed in this paper to reduce the errors and randomness of estimation results for this kind of degradation problems.Firstly,an improved unscented Kalman filtering is established utilizing the Kalman filtering(KF)method and a linear adaptive strategy.The linear adaptive strategy is used to adjust its noise term adaptively.Then,the robust RUL estimation is realized by the improved UKF.At last,three problems are investigated to demonstrate the effectiveness of the proposed method.