The Optimization of Preventive Maintenance Scheduling for Production Machine of Production System in Finite Time Horizon

The recursion relation of preventive maintenance (PM) cycle is built up concerning the concept of effective age and age setback factor proposed in this paper, which illustrates the dynamic relationship between failure rate and preventive maintenance activity. And the nonlinear optimal PM policy model satisfying the reliability constraints in finite time horizon following Weibull distribution is proposed. The model built in this paper avoids the shortcoming of steady analytical PM model in infinite time horizon and can be used to aid scheduling the maintenance plan and providing decision supporting for job shop scheduling.

China has become the largest producer and exporter of masks,protective clothing and other pandemic prevention supplies

Due to the effective control of the local COVID-19 pandemic,and the previous related production capacity has been greatly improved,China has become the largest producer and exporter of anti-pandemic products such as masks and protective clothing,helping many countries in the world to fight against pandemics.Except for China,reporters from the Global Times have reported that there are not many countries or regions that continue to export medical supplies.

Cancer burden in China:trends,risk factors and prevention

As the most populous country in the world,China has made strides in health promotion in the past few decades.With the aging population,the burden of cancer in China continues to grow.Changes in risk factors for cancer,especially diet,obesity,diabetes,and air pollution,continue to fuel the shift of cancer transition in China.The burden of upper gastrointestinal cancer in China is decreasing,but still heavy.The rising burden of colorectal,prostate,and breast cancers is also significant.Lung cancer became the top cause of cancer-related deaths,together with smoking as the most important contributor to cancer deaths.The Chinese government has taken several approaches to control cancer and cancer-related risk factors.Many achievements have been made,but some challenges remain.Health China 2030 is ambitious and depicts a bright vision of the future for cancer control in China.The decrease in the cancer burden in China will require cross-sector collaboration and coordinated efforts on primary and secondary preventions by governments,public health organizations,and individuals.In this review,we describe the trends of cancer burden and discuss cancer-related risk factors in China,identifying strategies to reduce the burden of cancer in China.

Parametric study on performance of bridge retrofitted by unseating prevention devices

Over the past decade, seismically induced damage to bridges has been widely reported following major earthquakes such as the 1994 Northridge, 1995 Kobe and 1999 Chi-Chi events. Since these earthquakes, restrainers and stoppers have been installed on bridges to prevent unseating and excessive displacements, respectively. Alternatively, column jacketing has also been proven to be effective. However, the enhanced shear strength may result in extra retrofitting works on the footing. For bridges damaged in the Chi-Chi earthquake, investigations revealed that most bridge columns experienced none-to-minor damage in the longitudinal direction. The reason for this unexpected performance was the construction practice of using a rubber bearing, which is an unbolted design that may slide under large lateral forces. In this paper, parametric studies on simply-supported bridges retrofitted by a restrainer or concrete shear key along the longitudinal and transverse axes were carried out. The research focuses on finding suitable combinations of the design force and gap spacing so the restrainer and concrete shear key can be used as an unseating prevention device, with respect to the allowable column damage in terms of displacement ductility under near-fault type earthquakes. A two-lane PCI-girder bridge was selected as the benchmark model. In the longitudinal direction, a total of nine combinations considering yielding strength and gap spacing for the restrainer were analyzed; while parameters for the concrete shear key were divided into three shear force levels and three gap spacings. In the transverse direction, a similar approach was adapted, except smaller gap spacing was used. For each of the above mentioned earthquakes, seven input ground motions were selected and their PGAs were adjusted to 0.36g and 0.45g as the Design earthquake and Maximum Considerable Earthquake, respectively. Based on the results of nonlinear time history analyses, proper parameters to design the restrainers and concrete shear keys are obtained. Responses obtained from numerical simulations under the Chi-Chi earthquake leaded to new implications to design those devices. Restrainer should not exceed its breaking strain and sufficient unseating length will be needed always. Concrete Shear key was determined by considering both displacement demand of the superstructure and displacement ductility of the column at the same time. Further study is needed to provide optimal design parameters for use in performance based bridge design.

The descriptive epidemiology of sitting in Chilean adults: Results from the National Health Survey 2009-2010

Background: Although evidence on the health effects of sedentary behavior(SB) has grown systematically in recent years, few developing countries have reported population levels of SB, especially in South America. Our objective was to describe time spent sitting in a representative sample from Chile categorized by age, gender, educational level, and body mass index(BMI).Methods: A national health survey was conducted in Chile in a nationally representative sample(n = 5411) in 2009-2010. Sitting time(ST) was measured with the Global Physical Activity Questionnaire Version 2.Results: Data were from 5031 participants(43.26±0.41 years, mean±SE; 40.3% male). Overall, there were no gender differences in mean ST(men: 158.10±5.80 min/day, women 143.45±4.77 min/day; p = 0.05). ST was lower in those who lived in rural areas compared with urban areas(99.4 min/day vs. 160.0 min/day; p = 0.001). ST increased significantly with increasing BMI, but only in men(p = 0.009), and was positively related to years of education in both men and women(p < 0.0001).Conclusion: The findings were different from those reported in other countries and contexts, reinforcing the need for international surveillance and monitoring over time to inform policy makers. Differences in ST across different groups emphasize the need to develop tailored messages and interventions for reducing ST in different population subgroups.

Assessing the effects of alternative fuel treatments to reduce wildfire exposure

Effective landscape-scale fuel management strategies are essential for reducing wildfire risk in Mediterranean fire-prone areas.In this study,the minimum travel time(MTT)fire-spread algorithm as implemented in FlamMap was applied to assess the potential of alternative fuel treatments for lowering wildfire losses in a 5,740-ha study area in eastern Sardinia,Italy.Twenty-seven wildfires at 10-m resolution were simulated considering three wind speeds(15,18,and 21 km h-1)to compare fuel treatments:no treatment(NT),irrigated agroforestry areas with shrub clearing(T1),prescribed fire in eucalyptus stands(T2),and irrigated grasslands(T3).The simulations replicated a recent large wildfire that occurred in the study area(Orrìwildfire,2019)and considered the weather and fuel moisture conditions associated with this event.The average wildfire exposure outputs(burned area,probability of burning,conditional flame length,potential crown fire occurrence,and surfaces withflame lengths above 2.5 m)decreased after fuel treatments,compared to no treatment.T1 was the most effective strategy in mitigating wildfire hazards and provided the most significant performance for several wildfire exposure indicators.Treating only 0.5%of the study area(~30 ha)resulted in a decrease in all wildfire exposure metrics to~10%within the study area.In addition,the total surface characterized by high flame length(average>2.5 m)was the lowest in the T1 treatment.This study can help land and fire managers optimize fuel treatment opportunities and wildfire risk mitigation strategies in Mediterranean areas.

A Functional Inspection Model for the Immeasurable Potential Failure State

Functional inspection is a type of preventive maintenance of Reliability Centered Maintenance （ RCM）. We, in this paper, establish a functional inspection model（ FIM） the cost model and the availability model for the immeasurable potential failure state based on the delay time concept. This model can be used to determine the appropriate Functional Inspection Interval（FII） to achieve the goal of specific cost and availability and to assist in maintenance decision making.

美国“Time-out”惩罚教育对幼儿园教育的启示

"Time-out"是美国幼儿园中较为常用的一种教育策略,用于应对儿童的不适宜或违纪行为。本文主要阐述了美国"Time-out"惩罚教育的含义及实施策略,以及它对幼儿园教育的启示。

Periodical Inspections and Delay Replacement Model Based on Age Preventive Replacement Policy

Periodical inspections and an age-based preventive replacement( APR) model were proposed based on a two-stage failure process for a single component system. Inspection activities were performed at regular intervals. Once the system was identified to be at defective state by inspection,a maintenance decision needed to be made that whether to replace the defective system immediately or wait till the preset APR time. So a threshold was introduced into the model and called as inspection-based preventive replacement( IPR) threshold. If the distance from the defect identification point to the APR time was longer than the threshold, a preventive replacement( PR) action was made; otherwise PR action was to wait till the APR time. Two models were proposed and compared,and a numerical example was conducted to illustrate the applicability of the model.

基于ATG实报的空中颠簸预防管理系统设计

在对颠簸伤害事件原因分析的基础上,设计了基于ATG实报的空中颠簸预防管理系统,该系统设计主要包括:开发QAR计算EDR程序,通过EDR指标提高颠簸预报精度;开发颠簸管理平台,实现颠簸信息的有效传递;利用ATG技术使颠簸预报向颠簸实报提升,提高颠簸信息的实时性。该解决方案可实现空地高精度颠簸风险实时自动预警,有效降低颠簸伤害。

Estrogen rapid effects:a window of opportunity for the aging brain?

Estrogen produces several beneficial effects in healthy neurological tissues and exhibits cardioprotective effects.Hormone therapy has been widely used to treat menopausal estrogen deficiency for more than 80 years.Despite high initial expectations of cardioprotective effects,there has been substantial distrust following important randomized clinical trials,such as the Women’s Health Initiative.Subsequently,the timing of treatment in relation to the onset of menopause came under consideration and led to the proposal of the timing hypothesis,that early initial treatment is important,and benefits are lost as the timing since menopause becomes prolonged.Subsequent analyses of the Women’s Health Initiative data,together with more recent data from randomized and observational trials,consistently show reductions in coronary heart disease and mortality in younger menopausal women.Regarding cognitive function,the timing hypothesis is consistent with observations from basic and animal studies.There is some clinical evidence to support the benefits of hormonal therapy in this context,though skepticism remains due to the paucity of clinical trials of substantial length in younger menopausal women.It is likely that the effects of estrogens on cognitive performance are due to rapid mechanisms,including mechanisms that influence Ca2+homeostasis dynamics,provide protection in a hostile environment and reduce inflammatory signals from neural tissues.In the future,inflammatory profiles accounting for early signs of pathological inflammation might help identify the‘window of opportunity’to use estrogen therapy for successful cognitive protection.

《刑法修正案(十二)》下行贿犯罪的均衡适用

《刑法修正案(十二)》对行贿犯罪的修改,旨在实现与受贿犯罪惩处的实质均衡,并增强行贿犯罪处罚条款的积极预防功能。这体现的是对行贿犯罪的预防性严惩,而非单纯对其进行严厉惩治。司法应遵循该修法精神指引,确保罪名适用的稳健性。为实现修正案关于贿赂犯罪的处罚均衡性目标,需要将预防性严惩的修法精神与宽严相济、从严治吏等一贯的刑事政策相结合,将“入罪认定总体稳健,量刑评价适度从严”作为新法适用方向。贿赂犯罪的保护法益为职务行为的自主决策权,对行贿犯罪的惩处力度取决于侵害该法益的具体形式,而非“受贿行贿同等罚”。新增的行贿罪从重处罚情节仅为量刑情节,应根据从重处罚的实质依据对各个情节进行目的性限缩解释,以确保司法适用的精确性与均衡性。

时间压力对工作退缩行为的影响机制研究

基于压力认知评价理论和调节焦点理论,通过对404个二阶段问卷样本的实证分析,探析时间压力对工作退缩行为的影响机制。研究结果表明:时间压力通过促进型调节焦点负向影响工作退缩行为,通过防御型调节焦点正向影响工作退缩行为;员工感知的过度工作氛围在时间压力与员工防御型调节焦点之间起负向调节作用,并进一步调节了防御型调节焦点的中介作用;触发工作退缩行为的前因构型包括:低收入×防御型调节焦点、时间压力×防御型调节焦点和低收入×低过度工作氛围×时间压力。

A Wireless Body Sensor Platform to Detect Progressive Deterioration in Musculoskeletal Systems

Recent developments in technology have helped to reduce the physical size and weight of devices and opened up new opportunities for their application in delivering unobtrusive healthcare services. In particular, kinetic and kinematic systems, that use sensors attached to the body, are currently being used to measure and understand many different aspects of human gait and behaviour. This has been particularly useful in treating stroke patients, rehabilitation, and understanding sedentary behaviour. Nonetheless, many of these systems are only capable of providing information about rudimentary movement rather than data on the mechanics of motion itself (tendons, ligaments and so on). Therefore, the information required by healthcare professionals to treat diseases like progressive deterioration of the musculoskeletal system, i.e. arthritis, cannot be determined. This paper discusses some of the technologies currently used to assess movement and posits a novel approach based on strain gauge technology to measure the constituent parts of a joint and its movement. In this way, the mechanics of motion can be studied and used to help detect and treat musculoskeletal diseases. A case study is presented to demonstrate the applicability of our approach.

基于Flink的动态感知用户兴趣漂移的电影推荐系统

传统使用Hadoop平台基于协同过滤算法搭建的分布式推荐系统,存在两个亟待解决的问题:(1)在面对海量数据与复杂的推荐算法模型时,处理数据的速度明显下降,不能做到低延时,无法对用户进行实时推荐;(2)传统基于协同过滤的推荐算法,无法实时感知用户兴趣漂移的问题,导致推荐的结果差强人意。针对以上两个问题,引入新一代流式计算引擎Flink,使用Spark、Flume、Kafka等大数据组件搭建电影推荐系统,整个推荐系统的推荐算法部分,分为离线与在线推荐两大模块,离线推荐算法引入堆排序,解决MLlib中ALS算法在模型预测时会进行笛卡尔积计算,消耗大量内存与算法执行时间长的问题;实时推荐算法引入艾宾浩斯遗忘曲线,通过融合时间权重与奖惩因子,来动态地感知用户兴趣发生漂移的问题。通过离线与在线推荐算法的改进,产生更好的个性化Top-N推荐结果,提升最终用户的体验。实验结果表明:(1)通过堆排序改进后的离线推荐ALS算法,在RMSE指标基本不变的情况下执行速率显著提高;(2)通过引入艾宾浩斯遗忘曲线,融合时间权重与奖惩因子的实时推荐算法,在准确率和召回率指标上明显提高,推荐结果更符合用户兴趣爱好;(3)Flink计算引擎相比较Spark计算引擎在数据量不断增加的情况下,算法执行速度更快。

可信拜占庭容错共识机制

针对实用拜占庭容错共识机制中存在共识效率低和激励机制不足的问题,提出一种可信拜占庭容错共识机制。首先,建立引入奖惩机制和时间衰减因子的节点信任评价模型,计算节点的信任值。然后,根据节点信任值进行排序,选择信任值高的节点组成共识节点集,利用可验证随机函数选取共识节点集中信任值高的节点作为主节点。此外,在拜占庭共识过程中利用BLS签名保证主节点不会作恶。实验仿真结果表明,信任模型可以有效惩罚作恶的节点,可信拜占庭容错共识相比于实用拜占庭容错共识交易吞吐量可以提高43%.

鲜水河构造带隧道高地应力区岩爆特性分析

研究目的:青藏高原持续隆升,导致鲜水河构造带及邻区高地应力特征突出,地应力场极其复杂,研究高地应力的孕灾特征有助于隧道岩爆的风险防控,特别是时滞型岩爆的孕灾和致灾机理的研究。本文阐述鲜水河构造带地貌、地层岩性、构造及地应力场特征的孕灾总体认识,通过对该区域隧道近10 km约1300次岩爆统计,从发生概率、等级、埋深、位置、时间、距离等多角度研究岩爆特征,对发生的5次时滞型岩爆和隧道时效性变化特征进行分析,展望后续岩爆研究的重点。研究结论:(1)鲜水河构造带及邻区受高地应力影响,隐伏小微构造发育且无规律,为岩爆创造了特殊的孕灾环境,岩爆发生的随机性大;(2)该区域隧洞岩爆等级以轻微岩爆为主,具有“分区破裂”和脆性变形特征,时滞型岩爆一定程度上具有“继承性”;(3)建议加强沟谷应力场低埋型岩爆和滞后型岩爆或硬岩潜在时效破坏的监测研究;(4)本文研究成果可为类似高地应力环境下岩爆预测和防控提供借鉴。

考虑运输时间和机器预维护的柔性作业车间绿色调度

针对柔性作业车间调度问题,在同时考虑运输时间、机器预维护和能耗等约束的情况下,建立了最小化完工时间和总能耗的混合整数规划模型,并提出一种多目标离散Jaya算法进行求解。根据问题的特点,设计了基于工序和机器的双层编码方式,并采用均衡加工时间和能耗的种群初始化方法产生高质量的初始种群。为了将解转化为可行有效的调度方案,设计了带有预维护动态调整策略和考虑运输时间的贪婪插入解码方法。根据解的不同情况,采用不同的方式更新个体。将本文设计的算法与常用的多目标优化算法在18组不同规模的测试算例下进行对比分析,验证了所提算法的有效性。实验结果表明,所提算法能够有效解决考虑运输时间和机器预维护的柔性作业车间绿色调度问题。

利用长时序卫星影像评估防沙治沙区植被变化

为了探究西北荒漠区防沙治沙成效定量评估的技术方法,本文以古浪县北部防沙治沙区为研究范围,基于2000—2021年的11期Landsat影像,利用像元二分模型反演植被覆盖度、趋势分析法等对研究区的植被覆盖度变化趋势与空间特征进行了分析,并从自然因素与人为因素两方面对引起植被覆盖度变化的因素进行了探究。结果表明:①2000—2021年,古浪县北部防沙治沙区植被覆盖度呈现波动上升趋势,在2019年达到监测期内的最大值。不同类型沙地的植被覆盖度呈现明显的差异,平均植被覆盖度由大到小分别为:固定沙地>半流动沙地>盐碱地>半固定沙地>流动沙地。②植被覆盖度明显改善的区域主要位于沙漠与绿洲的交界地带;在沙漠南部边缘存在由于人类开发建设产生的植被退化区域;在沙漠北部,植被覆盖基本稳定区域、轻微退化区域、中度改善区域、轻微改善区域呈南北方向的条带状间错分布。③防沙治沙区植被覆盖度变化除受降水影响外,还与当地政府实施的许多重大防沙治沙工程有关。

ESG信息披露能否抑制股票价格波动风险?

基于2009—2022年沪深两市A股上市公司的样本数据,使用多时点双重差分法探究ESG信息披露对股票价格波动风险的影响。通过实证分析发现:ESG信息披露抑制了股票价格波动风险,这一结论在经过一系列稳健性检验后依然成立。机制检验结果显示:ESG披露主要通过降低机构投资者抱团来抑制股价波动。进一步分析发现:外部的媒体关注强化了ESG信息披露的风险降低效应。异质性检验表明:在制造业等特定行业、信息披露质量高以及中、东部地区的企业中,ESG披露对股价波动风险的抑制作用更强。研究在理论上为探索ESG信息披露的经济后果研究提供了新的视角,在实践上为资本市场的发展与稳定以及风险防范提供了一定的经验证据。