无人机辅助物联网中基于Safe Actor-Critic的信息年龄最小化研究

无人机作为一种新的通信设备,有望在物联网数据采集、监控等业务中发挥关键作用。为保证所采集数据的时效性,利用信息年龄来衡量无人机从物联网设备接收到的数据新鲜度。通过联合优化无人机轨迹和无人机与物联网设备的关联策略以最小化信息年龄加权和,并保证无人机累积飞行能量消耗满足预算要求。由于上述问题同时受短期和长期约束条件的限制,将问题建模为受约束的马尔可夫决策过程(CMDP),并利用Safe Actor-Critic来求解。仿真结果表明,所提算法在最小化信息年龄的同时,能有效保证能量预算。

A cross-sectional study to assess medication safety,knowledge,attitude,and practices regarding nutrition and medication among pregnant women

Objective:To assess pregnant women's knowledge,attitude,and practice regarding nutrition and medication usage,analyse the prescribing pattern,and categorize them based on the Food and Drug Administration(FDA)guidelines.Methods:A cross-sectional study was conducted with 264 pregnant women in the obstetrics and gynaecology department of a tertiary care hospital from October 2022 to August 2023.A knowledge,attitude,and practice(KAP)questionnaire was prepared in English language by the researchers and validated by an expert panel consisting of 12 members.The validated questionnaire was then translated into regional languages,Kannada and Malayalam.The reliability of the questionnaire was assessed with test-retest method with a representative sample population of 30 subjects(10 subjects for each language).The subjects'knowledge,attitude,and practice were evaluated using the validated KAP questionnaire.The safety of the medication was assessed using the FDA drug safety classification for pregnancy.Results:The mean scores for nutritional and medication usage knowledge,attitude,and practice were 4.14±1.15,4.50±1.09,and 3.00±1.47,respectively.Among 30 prescribed medications,3 belong to category A(no risk in human studies),8 belong to category B(no risk in animal studies),18 belong to category C(risk cannot be ruled out)and 1 drug is not classified.A significant association was observed between medication knowledge and practice(r=0.159,P=0.010).Conclusions:Most of the study population knows the need to maintain good dietary and medication practices during pregnancy.Counselling pregnant women regarding diet and medication usage is crucial in maternal care.

A Game-Theoretic Approach to Safe Crowd Evacuation in Emergencies

Obstacle removal in crowd evacuation is critical to safety and the evacuation system efficiency. Recently, manyresearchers proposed game theoreticmodels to avoid and remove obstacles for crowd evacuation. Game theoreticalmodels aim to study and analyze the strategic behaviors of individuals within a crowd and their interactionsduring the evacuation. Game theoretical models have some limitations in the context of crowd evacuation. Thesemodels consider a group of individuals as homogeneous objects with the same goals, involve complex mathematicalformulation, and cannot model real-world scenarios such as panic, environmental information, crowds that movedynamically, etc. The proposed work presents a game theoretic model integrating an agent-based model to removethe obstacles from exits. The proposed model considered the parameters named: (1) obstacle size, length, andwidth, (2) removal time, (3) evacuation time, (4) crowd density, (5) obstacle identification, and (6) route selection.The proposed work conducts various experiments considering different conditions, such as obstacle types, obstacleremoval, and several obstacles. Evaluation results show the proposed model’s effectiveness compared with existingliterature in reducing the overall evacuation time, cell selection, and obstacle removal. The study is potentially usefulfor public safety situations such as emergency evacuations during disasters and calamities.

Risk-Informed Model-Free Safe Control of Linear Parameter-Varying Systems

This paper presents a risk-informed data-driven safe control design approach for a class of stochastic uncertain nonlinear discrete-time systems.The nonlinear system is modeled using linear parameter-varying(LPV)systems.A model-based probabilistic safe controller is first designed to guarantee probabilisticλ-contractivity(i.e.,stability and invariance)of the LPV system with respect to a given polyhedral safe set.To obviate the requirement of knowing the LPV system model and to bypass identifying its open-loop model,its closed-loop data-based representation is provided in terms of state and scheduling data as well as a decision variable.It is shown that the variance of the closedloop system,as well as the probability of safety satisfaction,depends on the decision variable and the noise covariance.A minimum-variance direct data-driven gain-scheduling safe control design approach is presented next by designing the decision variable such that all possible closed-loop system realizations satisfy safety with the highest confidence level.This minimum-variance approach is a control-oriented learning method since it minimizes the variance of the state of the closed-loop system with respect to the safe set,and thus minimizes the risk of safety violation.Unlike the certainty-equivalent approach that results in a risk-neutral control design,the minimum-variance method leads to a risk-averse control design.It is shown that the presented direct risk-averse learning approach requires weaker data richness conditions than existing indirect learning methods based on system identification and can lead to a lower risk of safety violation.Two simulation examples along with an experimental validation on an autonomous vehicle are provided to show the effectiveness of the presented approach.

Enhanced Memory-Safe Linux Security Modules (eLSMs) for Improving Security of Docker Containers for Data Centers

The adoption of Docker containers has revolutionized software deployment by providing a lightweight and efficient way to isolate applications in data centers. However, securing these containers, especially when handling sensitive data, poses significant challenges. Traditional Linux Security Modules (LSMs) such as SELinux and AppArmor have limitations in providing fine-grained access control to files within containers. This paper presents a novel approach using eBPF (extended Berkeley Packet Filter) to implement a LSM that focuses on file-oriented access control within Docker containers. The module allows the specification of policies that determine which programs can access sensitive files, providing enhanced security without relying solely on the host operating system’s major LSM.

A Dual-Task Learning Approach for Bearing Anomaly Detection and State Evaluation of Safe Region

Predictive maintenance has emerged as an effective tool for curbing maintenance costs,yet prevailing research predominantly concentrates on the abnormal phases.Within the ostensibly stable healthy phase,the reliance on anomaly detection to preempt equipment malfunctions faces the challenge of sudden anomaly discernment.To address this challenge,this paper proposes a dual-task learning approach for bearing anomaly detection and state evaluation of safe regions.The proposed method transforms the execution of the two tasks into an optimization issue of the hypersphere center.By leveraging the monotonicity and distinguishability pertinent to the tasks as the foundation for optimization,it reconstructs the SVDD model to ensure equilibrium in the model’s performance across the two tasks.Subsequent experiments verify the proposed method’s effectiveness,which is interpreted from the perspectives of parameter adjustment and enveloping trade-offs.In the meantime,experimental results also show two deficiencies in anomaly detection accuracy and state evaluation metrics.Their theoretical analysis inspires us to focus on feature extraction and data collection to achieve improvements.The proposed method lays the foundation for realizing predictive maintenance in a healthy stage by improving condition awareness in safe regions.

Study on the Safety and Prevention Technology of Coal Mining under the River in Xingyuan Coal Mine

Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This project aims to address the extensive impact of coal mining on the environment, infrastructure, and overall safety, focusing on the Shigong River area above the working face. The study employs qualitative and quantitative analyses, along with on-site engineering measurements, to gather data on crucial parameters such as coal seam characteristics, roof rock lithology, thickness, water resistance, and structural damage degree. The research encompasses a multidisciplinary approach, involving mining, geology, hydrogeology, geophysical exploration, rock mechanics, mine surveying, and computational mathematics. The importance of effective safety measures and prevention techniques is emphasized, laying the foundation for research focused on the Xingyun coal mine. The brief concludes by highlighting the potential economic and social benefits of this project and its contribution to valuable experience for future subsea coal mining.

Smart materials for safe lithium-ion batteries against thermal runaway

In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.

Application and Effect Evaluation of the Integrated“5A and 3+3”Management Model in the Safe Medication Use for Chemotherapy Patients

Objective:To explore the application and effect evaluation of the integrated“5A and 3+3”management model in ensuring safe medication use for chemotherapy patients.Methods:A total of 100 intravenous chemotherapy patients admitted to the oncology department of Shaanxi Provincial People’s Hospital were randomly divided into two groups using a random number list method.Both groups received conventional nursing management during chemotherapy,while the study group additionally received the integrated“5A and 3+3”safety management model.The nursing intervention effects between the two groups were compared.Results:After the intervention,the study group showed higher levels of self-management ability,compliance,and nursing satisfaction compared to the control group.The overall incidence of adverse events during hospitalization was lower in the study group,with statistically significant differences(P<0.05).The knowledge scores of medical staff in the study group,related to the prevention and treatment of chemotherapy drug side effects,daily symptom management,and daily life management,were higher than those in the control group,with statistically significant differences(P<0.05).Conclusion:Implementing the integrated“5A and 3+3”model in the safe medication management of intravenous chemotherapy patients can effectively enhance patients’self-management abilities and compliance,improve medical staff’s ability to safely administer chemotherapy drugs,reduce adverse events caused by chemotherapy,and increase patient satisfaction.

Trimming the Degrees of Freedom via a K^(+) Flux Rectifier for Safe and Long‑Life Potassium‑Ion Batteries

High degrees of freedom(DOF)for K^(+)movement in the electrolytes is desirable,because the resulting high ionic conductivity helps improve potassium-ion batteries,yet requiring support from highly free and flammable organic solvent molecules,seriously affecting battery safety.Here,we develop a K^(+)flux rectifier to trim K ion’s DOF to 1 and improve electrochemical properties.Although the ionic conductivity is compromised in the K^(+)flux rectifier,the overall electrochemical performance of PIBs was improved.An oxidation stability improvement from 4.0 to 5.9 V was realized,and the formation of dendrites and the dissolution of organic cathodes were inhibited.Consequently,the K||K cells continuously cycled over 3,700 h;K||Cu cells operated stably over 800 cycles with the Coulombic efficiency exceeding 99%;and K||graphite cells exhibited high-capacity retention over 74.7%after 1,500 cycles.Moreover,the 3,4,9,10-perylenetetracarboxylic diimide organic cathodes operated for more than 2,100 cycles and reached year-scale-cycling time.We fabricated a 2.18 Ah pouch cell with no significant capacity fading observed after 100 cycles.

Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries

Solid polymer electrolytes(SPEs)are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries.Nevertheless,the poor ionic conductivity at room temperature(RT)and low resistance to Li dendrites seriously hinder the commercialization of SPEs.Herein,we design a bifunctional flame retardant SPE by combining hydroxyapatite(HAP)nanomaterials with Nmethyl pyrrolidone(NMP)in the PVDF-HFP matrix.The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of Li TFSI in the PVDF-HFP matrix.Consequently,the prepared SPE demonstrates superior ionic conductivity at RT,excellent fireproof properties,and strong resistance to Li dendrites.The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 m A cm^(-2),and the solid-state LiFePO_4||Li cell shows excellent capacity retention of 85.3%over 600 cycles at 0.5 C.

The collagen type Ⅰ alpha 1 chain gene is an alternative safe harbor locus in the porcine genome

Efficient and stable expression of foreign genes in cells and transgenic animals is important for gain-of-function studies and the establishment of bioreactors.Safe harbor loci in the animal genome enable consistent overexpression of foreign genes,without side effects.However,relatively few safe harbor loci are available in pigs,a fact which has impeded the development of multi-transgenic pig research.We report a strategy for efficient transgene knock-in in the endogenous collagen type I alpha 1 chain(COL1A1)gene using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system.After the knock-in of a 2A peptide-green fluorescence protein(2A-GFP)transgene in the last codon of COL1A1 in multiple porcine cells,including porcine kidney epithelial(PK15),porcine embryonic fibroblast(PEF)and porcine intestinal epithelial(IPI-2I)cells,quantitative PCR(qPCR),Western blotting,RNA-seq and CCK8 assay were performed to assess the safety of COL1A1 locus.The qPCR results showed that the GFP knock-in had no effect(P=0.29,P=0.66 and P=0.20 for PK15,PEF and IPI-2I cells,respectively)on the mRNA expression of COL1A1 gene.Similarly,no significant differences(P=0.64,P=0.48 and P=0.80 for PK15,PEF and IPI-2I cells,respectively)were found between the GFP knock-in and wild type cells by Western blotting.RNA-seq results revealed that the transcriptome of GFP knock-in PEF cells had a significant positive correlation(P<2.2e–16)with that of the wild type cells,indicating that the GFP knock-in did not alter the global expression of endogenous genes.Furthermore,the CCK8 assay showed that the GFP knock-in events had no adverse effects(P_(24)h=0.31,P_(48)h=0.96,P_(72)h=0.24,P_(96)h=0.17,and P_(120)h=0.38)on cell proliferation of PK15 cells.These results indicate that the COL1A1 locus can be used as a safe harbor for foreign genes knock-in into the pig genome and can be broadly applied to farm animal breeding and biomedical model establishment.

Determining safe yield and mapping water level zoning in groundwater resources of the Neishabour Plain

Groundwater is a crucial sources of water supply,especially in arid and semi-arid areas around the world.With uncontrolled withdrawals and limited availability of these resources,it is essential to determine the safe yield of these valuable resources.The Hill method approach was used in this study to determine the safe yield the Neishabour aquifer in Khorasan Razvi province in Iran.The results showed that the safe yield in the Neishabour aquifer is 60%lower than the current pumping amounts during the study period,indicating that further overdrafts could result in the destruction of this aquifer.This highlights the importance of using the Hill method to estimate the permitted exploitation from other aquifers,thus preventing problems caused by over-extraction and maintaining stability of global groundwater levels.

Morbi-Mortality Linked to Unsafe Abortions—Difficulties in Accessing Safe Abortions in Cameroon: Meta-Analysis and Systematic Review

Background: Unsafe abortions are one of the leading causes of maternal mortality, especially in developing countries. In Cameroon, the maternal mortality rate remains high, and the scarcity of data on abortions leads to a lack of solid evidence to advocate on the extent of the abortions related complications. Our objective was to evaluate the unsafe abortions related complications, and to assess the difficulties of accessing safe abortions in our setting. Methods: We carried out a meta-analytic and systematic review in the biomedical databases MEDLINE (Pubmed), Google Scholar and African Journal Online concerning unsafe abortions and/or difficulties in accessing safe abortions in Cameroon. The keywords used for the search are seen in table I. Selection of studies was simultaneously done by two authors. Data were extracted through a form designed on Google Form. We used a random-effect model for proportion estimation, and The I2 and Q statistics to assess the extent of heterogeneity. Results: A total of 430 studies were identified, from which 28 were included and analysed. About 5% (95% CI: 3 - 7) of unsafe abortions leads to death. The contribution of unsafe abortions in maternal deaths was 23% (95% CI: 20 - 27). The rate of severe bleeding and/or anemia were 40% (95% CI: 18 - 63) and the rate of infection was 17% (95% CI: 7 - 28), dominated by pelvic infections, pelviperitonitis, severe sepsis, and septic shock. Case reports described uterine perforations, uterine rupture during the following pregnancy. Abortion was performed in the practitioner’s or patient’s home in 41.4% of cases, in a health center in 35.1% of cases, in a private clinic in 21.2% of cases, drugs selling places and in traditional healer clinics. The restriction of abortion laws, the stigma surrounding abortion and its consequences at any level of the society, lead to the underreporting of unsafe abortions and a deep reluctance to advocate for safe abortion services. Conclusion: The strengthening of awareness campaigns for provider behavior change communication, family planning, the de-stigmatization of abortions, the training of health personnel in post-abortion care, a multidisciplinary and multicentric action would contribute to the reduction in morbidity and mortality due to abortions.

A surfactant-modified composite separator for high safe lithium ion battery

Separators have been gaining increasing attention to improve the performance of lithium ion batteries(LIBs),especially for high safe and long cycle life.However,commercial polyolefin separators still face the problems of rapid capacity decay and safety issues due to the poor wettability with electrolytes and low thermal stability.Herein,a novel composite separator is proposed by introducing a surfactant of sodium dodecyl thiosulfate(SDS)into the polytetrafluoroethylene(PTFE)substrate with the binder of polyacrylic acid(PAA)through the suction filtration method.The introduction of PAA/SDS enhances the adsorption energy between PTFE substrate and electrolyte through density functional theory calculations,which improves wettability and electrolyte uptake of the separator significantly.The asachieved composite separator enables the LIBs to own high Li^(+)conductivity(0.64×10^(-3)S cm^(-1))and Li^(+)transference number(0.63),further leading to a high capacity retention of 93.50%after 500 cycles at 1 C.In addition,the uniform and smooth surface morphology of Li metal employed the composite separator after cycling indicates that the lithium dendrites can be successfully inhibited.This work indicates a promising route for the preparation of a novel composite separator for high safe LIBs.

基于Safe-PPO算法的安全优先路径规划方法

现有的路径规划算法对路径规划过程中的路径安全性问题考虑较少,并且传统的近端策略优化(PPO)算法存在一定的方差适应性问题。为解决这些问题,提出一种融合进化策略思想和安全奖励函数的安全近端策略优化(Safe-PPO)算法,所提算法以安全优先进行路径规划。采用协方差自适应调整的进化策略(CMA-ES)的思想对PPO算法进行改进,并引入危险系数与动作因子来评估路径的安全性。使用二维栅格地图进行仿真实验,采用传统的PPO算法和Safe-PPO算法进行对比;采用六足机器人在搭建的场景中进行实物实验。仿真实验结果表明:所提算法在安全优先导向的路径规划方面具有合理性与可行性:在训练时Safe-PPO算法相比传统的PPO算法收敛速度提升了18%,获得的奖励提升了5.3%;在测试时采用融合危险系数与动作因子的方案能使机器人学会选择更加安全的道路而非直观上最快速的道路。实物实验结果表明:机器人可以在现实环境中选择更加安全的路径到达目标点。

Are life insurance futures a safe haven during COVID‑19?

This study aims to examine whether life insurance futures can serve as a hedge against the COVID-19 pandemic and whether they have the characteristics of a safe haven under the impact of the health shocks of the COVID-19 pandemic.We chose three life insurance stock futures in India and one in Taiwan as samples,including the market index of the two countries and the number of confirmed COVID-19 cases as sample variables.We used the growth rate of COVID-19 cases as the threshold variable,esti-mated the asymmetric threshold vector autoregression model,and found that insur-ance futures in the regime with a significant growth rate of confirmed COVID-19 cases can hedge against COVID-19 risks;therefore,insurance futures are a safe haven for the market.We further estimated the time-varying parameter vector autoregression model,and the impulse response results showed that insurance futures are a safe haven for COVID-19 pandemic risks.

SiC trench MOSFET with dual shield gate and optimized JFET layer for improved dynamic performance and safe operating area capability

A novel silicon carbide(SiC) trench metal–oxide–semiconductor field-effect transistor(MOSFET) with a dual shield gate(DSG) and optimized junction field-effect transistor(JFET) layer(ODSG-TMOS) is proposed. The combination of the DSG and optimized JFET layer not only significantly improves the device’s dynamic performance but also greatly enhances the safe operating area(SOA). Numerical analysis is carried out with Silvaco TCAD to study the performance of the proposed structure. Simulation results show that comparing with the conventional asymmetric trench MOSFET(Con-ATMOS), the specific on-resistance(Ron,sp) is significantly reduced at almost the same avalanche breakdown voltage(BVav). Moreover, the DSG structure brings about much smaller reverse transfer capacitance(Crss) and input capacitance(Ciss), which helps to reduce the gate–drain charge(Qgd) and gate charge(Qg). Therefore, the high frequency figure of merit(HFFOM) of Ron,sp·Qgdand Ron,sp· Qgfor the proposed ODSG-TMOS are improved by 83.5% and 76.4%, respectively.The switching power loss of the proposed ODSG-TMOS is 77.0% lower than that of the Con-ATMOS. In addition, the SOA of the proposed device is also enhanced. The saturation drain current(Id,sat) at a gate voltage(Vgs) of 15 V for the ODSGTMOS is reduced by 17.2% owing to the JFET effect provided by the lower shield gate(SG) at a large drain voltage. With the reduced Id,sat, the short-circuit withstand time is improved by 87.5% compared with the Con-ATMOS. The large-current turn-off capability is also improved, which is important for the widely used inductive load applications.

Fruit Safety Production Technology

The edible safety factor of fruit can be greatly improved by the following measures:avoiding industrial and mining pollution areas in orchard construction;reasonable shaping and trimming to maintain good light and ventilation conditions;strengthening soil,fertilizer and water management,and increasing the application of organic fertilizer to enhance the resistance of trees to bacterial infection;growing grass and mulching to avoid the exposure of soil surface and prevent the spread of harmful soil-derived bacteria;trapping pests and delaying their damage in the tree,to facilitate centralized killing;preventing and treating diseases and pests through biological and physical non-pharmaceutical means such as underplanting,solar insecticidal lamps,sex attractant,sweet and sour liquid,ozonizer,etc.;strengthening the use of mineral-based,plant-derived and biological agents,and reducing the use of chemical pesticides to avoid pesticide residues.

Disturbance Observer-Based Safe Tracking Control for Unmanned Helicopters With Partial State Constraints and Disturbances

In this paper, a disturbance observer-based safe tracking control scheme is proposed for a medium-scale unmanned helicopter with rotor flapping dynamics in the presence of partial state constraints and unknown external disturbances. A safety protection algorithm is proposed to keep the constrained states within the given safe-set. A second-order disturbance observer technique is utilized to estimate the external disturbances. It is shown that the desired tracking performance of the controlled unmanned helicopter can be achieved with the application of the backstepping approach, dynamic surface control technique, and Lyapunov method. Finally, the availability of the proposed control scheme has been shown by simulation results.