An opportunistic maintenance model is presented for a continuously deteriorating series system with economical de-pendence. The system consists of two kinds of units, which are respectively subjected to the deteriorat...An opportunistic maintenance model is presented for a continuously deteriorating series system with economical de-pendence. The system consists of two kinds of units, which are respectively subjected to the deterioration failure described by Gamma process and the random failure described by Poisson process. A two-level opportunistic policy defined by three decision parameters is proposed to coordinate the different maintenance actions and minimize the long-run maintenance cost rate of the system. A computable expression of the average cost rate is established by using the renewal property of the stochastic process of the maintained system state. The optimal values of three deci- sion parameters are derived by an iteration approach based on the characteristic of Gamma process. The behavior of the proposed policy is illustrated through a numerical experiment. Comparative study with the widely used corrective maintenance policy demonstrates the advantage of the proposed opportunistic maintenance method in significantly reducing the maintenance cost. Simultane- ously, the applicable area of this opportunistic model is discussed by the sensitivity analysis of the set-up cost and random failure rate.展开更多
Modular unit systems provide an eco-friendly advanced construction method that improves productivity and reduces carbon emissions and construction waste. In these systems, the prefabrication ratio of the modules shoul...Modular unit systems provide an eco-friendly advanced construction method that improves productivity and reduces carbon emissions and construction waste. In these systems, the prefabrication ratio of the modules should be high in order to support these eco-friendly features. The purpose of this study was to verify the functionality and driving safety of fixing a modular unit with a high prefabrication ratio to a vehicle for transportation to the site using two novel adapter blocks specially developed for this purpose. When asked to evaluate their performance for this study, the truck drivers selected adaptor block type B as providing the highest convenience and functionality. In real-world driving experiments, maximum loads of 15 kN and 25 kN were measured on adapter block types A and B, respectively. Future improvements in the adapter blocks that take the safety ratio and the improved convenience of use into account are confidently expected to contribute to the eco-friendliness and the improved productivity of modular unit systems.展开更多
The new energy power generation is becoming increasingly important in the power system.Such as photovoltaic power generation has become a research hotspot,however,due to the characteristics of light radiation changes,...The new energy power generation is becoming increasingly important in the power system.Such as photovoltaic power generation has become a research hotspot,however,due to the characteristics of light radiation changes,photovoltaic power generation is unstable and random,resulting in a low utilization rate and directly affecting the stability of the power grid.To solve this problem,this paper proposes a coordinated control strategy for a newenergy power generation system with a hybrid energy storage unit based on the lithium iron phosphate-supercapacitor hybrid energy storage unit.Firstly,the variational mode decomposition algorithm is used to separate the high and low frequencies of the power signal,which is conducive to the rapid and accurate suppression of the power fluctuation of the energy storage system.Secondly,the fuzzy control algorithm is introduced to balance the power between energy storage.In this paper,the actual data is used for simulation,and the simulation results show that the strategy realizes the effective suppression of the bus voltage fluctuation and the accurate control of the internal state of the energy storage unit,effectively avoiding problems such as overshoot and over-discharge,and can significantly improve the stability of the photovoltaic power generation systemand the stability of the Direct Current bus.It is of great significance to promote the development of collaborative control technology for photovoltaic hybrid energy storage units.展开更多
Large-scale new energy grid connection leads to the weakening of the system frequency regulation capability,and the system frequency stability is facing unprecedented challenges.In order to solve rapid frequency fluct...Large-scale new energy grid connection leads to the weakening of the system frequency regulation capability,and the system frequency stability is facing unprecedented challenges.In order to solve rapid frequency fluctuation caused by new energy units,this paper proposes a new energy power system frequency regulation strategy with multiple units including the doubly-fed pumped storage unit(DFPSU).Firstly,based on the model predictive control(MPC)theory,the state space equations are established by considering the operating characteristics of the units and the dynamic behavior of the system;secondly,the proportional-differential control link is introduced to minimize the frequency deviation to further optimize the frequency modulation(FM)output of the DFPSU and inhibit the rapid fluctuation of the frequency;lastly,it is verified on theMatlab/Simulink simulation platform,and the results show that the model predictive control with proportional-differential control link can further release the FM potential of the DFPSU,increase the depth of its FM,effectively reduce the frequency deviation of the system and its rate of change,realize the optimization of the active output of the DFPSU and that of other units,and improve the frequency response capability of the system.展开更多
BACKGROUND Prolonged immobility during intensive care unit(ICU)admission has been a cause of muscle atrophy and worsening functional outcomes with longer recovery times.Prior research has demonstrated that mobilizatio...BACKGROUND Prolonged immobility during intensive care unit(ICU)admission has been a cause of muscle atrophy and worsening functional outcomes with longer recovery times.Prior research has demonstrated that mobilization within a week of ICU admission potentially benefits physical function in critically ill patients.AIM To evaluate the effects of initiating mobilization within 72 hours of ICU admission in critically ill patients through an updated systematic review and meta-analysis.METHODS A systematic search was performed through MEDLINE,Scopus,and Cochrane Library from inception until September 2024 for randomized controlled trials(RCTs)comparing early mobilization(EM)with usual or conventional care in critically ill adult patients.Primary outcomes included length of ICU(days)and ventilation duration(days).Secondary outcomes included muscle strength,functional status,adverse events,all-cause mortality,and quality of life(QOL).A random effects meta-analysis was performed for pooled effect estimates and to derive risk ratios(RR)and corresponding 95%confidence intervals(CI).RESULTS Out of 3487 results,16 RCTs were included with a population of 2385 patients(1195 receiving EM and 1190 with usual care.)A significant reduction in the length of ICU stays[mean difference(MD)=-1.02,95%CI:-1.96 to-0.09;P=0.03;I2=60%]and ventilation duration(MD=-1.07,95%CI:-1.91 to-0.23,P=0.01;I2=57%)was observed in the EM group compared to usual care.EM significantly improved muscle strength[standard MD(SMD)=0.47,95%CI:0.18-0.75,P=0.001;I2=79%]and functional status(SMD=0.70,95%CI:0.40-1.00,P<0.00001;I2=81%)in ICU patients.No statistically significant difference was observed in adverse events(RR=1.72,95%CI:1.01-2.94,P=0.05;I2=31%),all-cause mortality(RR=1.10,95%CI:0.79-1.53,P=0.57;I2=30%),and QOL(SMD=0.04,95%CI:-0.07-0.15,P=0.50;I2=9%)between the two groups.CONCLUSION Initiating mobilization within 72 hours of ICU admission is associated with improved functional outcomes and reduced ICU length of stay and ventilation duration.These findings indicate that EM may be a safe option for ICU patients,contributing to lower recovery times and healthcare costs.Further extensive research is required to validate the long-term effects on survival and QOL.展开更多
Cultural rights are important human rights established by the Universal Declaration of Human Rights(UDHR)and the International Covenant on Economic,Social and Cultural Rights(ICESCR).However,they have not received due...Cultural rights are important human rights established by the Universal Declaration of Human Rights(UDHR)and the International Covenant on Economic,Social and Cultural Rights(ICESCR).However,they have not received due attention within the United Nations human rights system and related academic research.As a specialized agency within the United Nations system primarily responsible for cultural affairs,United Nations Educational,Scientific and Cultural Organization(UNESCO)has played a significant role in promoting the recognition and advocacy of cultural rights in the international community,mainly by expanding and deepening the normative connotations of cultural rights,strengthening the integration of culture and cultural rights with the United Nations’development agenda,and creating cultural heritage rights and other specific examples of protection practices.Under its leadership,the United Nations system is exploring a new agenda of collective actions to promote cultural rights,which shows a trend of emphasizing cross-sectoral collaboration between culture and science,as well as culture and education.Guided by Xi Jinping Thought on Culture,China should further leverage the advantages of UNESCO as a global cultural governance platform to share its concepts and experience in protecting and realizing cultural rights with the international community.Through the Global Civilization Initiative,China can lead and shape the emerging international agenda on cultural rights and promote the progress of international human rights and the building of a community with a shared future for mankind.展开更多
In this paper,a strength-constrained unit commitment(UC)model incorporating system strength constraints based on the weighted short-circuit ratio(WSCR)is proposed.This model facilitates the comprehensive assessment of...In this paper,a strength-constrained unit commitment(UC)model incorporating system strength constraints based on the weighted short-circuit ratio(WSCR)is proposed.This model facilitates the comprehensive assessment of area-wide system strength in power systems with high inverter-based resource(IBR)penetration,thereby contributing to the mitigation of weak grid issues.Unlike traditional models,this approach considers the interactions among multiple IBRs.The UC problem is initially formulated as a mixed-integer nonlinear programming(MINLP)model,reflecting WSCR and bus impedance matrix modification constraints.To enhance computational tractability,the model is transformed into a mixed-integer linear programming(MILP)form.The effectiveness of the proposed approach is validated through simulations on the IEEE 5-bus,IEEE 39-bus,and a modified Korean power system,demonstrating the ability of the proposed UC model enhancing system strength compared to the conventional methodologies.展开更多
BACKGROUND Systemic lupus erythematosus(SLE)patients are admitted to the intensive care unit(ICU)for disease flares and infections,both of which carry a high mortality risk.Studies characterizing the outcome predictor...BACKGROUND Systemic lupus erythematosus(SLE)patients are admitted to the intensive care unit(ICU)for disease flares and infections,both of which carry a high mortality risk.Studies characterizing the outcome predictors of SLE are few in the Asian continent.This study characterized the clinical profile,treatment,and outcome predictors of ICU admissions with SLE.AIM To ascertain the reasons for ICU admission among SLE patients and to explore outcome predictors in these patients.The primary outcome was ICU mortality.Secondary outcomes included need for ventilation,inotropes,renal replacement therapy,and length of ICU and hospital stay.METHODS A retrospective study of 77 SLE patients was conducted in the medical ICU of a tertiary care teaching hospital in India.Clinical features,treatment,and outcomes of patients admitted between January 2018 and December 2022 were recorded.Factors associated with mortality were explored using bivariate and multivariate logistic regression analysis and reported as adjusted odds ratios with 95%confidence intervals.RESULTS The mean(SD)age was 31.1(10.3)years;83.1%were female.The median(interquartile)duration of SLE before admission was 12(1-60)months;SLE was newly diagnosed in the current admission in 23.4%.The median Acute Physiology and Chronic Health Evaluation II score was 16.3(14.5-18.2)and similar among survivors and nonsurvivors;32 had evidence of disease flare,44 had an infection,and one patient had an intracranial bleed.ICU admission was for respiratory failure(46.7%),hemodynamic instability(32.5%),and status epilepticus(14.3%).Twenty-nine patients(37.7%)had autoimmune hemolytic anemia,and 11(14.3%)had diffuse alveolar hemorrhage.Immunomodulation included corticosteroids(96.1%),cyclophosphamide(33.8%),mycophenolate(23.4%),plasma exchange(13%),and immunoglobulins(11.7%).All patients received broad-spectrum antibiotics.Respiratory support,inotropes,and renal replacement therapy were required in 93.5%,51.7%,and 32.5%,respectively.ICU mortality was 50.7%(95%confidence interval:39%-62%).The mean±SD hospital length of stay was 18.9±14.3 days.On multivariate analysis,only shock(P=0.004)was independently associated with mortality.CONCLUSION Intercurrent infection and disease flare are common reasons for ICU admission in SLE patients.Despite multimodal therapy,mortality is high.Shock was independently associated with mortality.展开更多
BACKGROUND Parental presence in neonatal units(NUs)is essential for infant development and family well-being.A deeper understanding of the factors influencing parental presence is vital and will contribute to the deve...BACKGROUND Parental presence in neonatal units(NUs)is essential for infant development and family well-being.A deeper understanding of the factors influencing parental presence is vital and will contribute to the development of targeted interventions and policies that enhance parental engagement in neonatal care,thereby improving outcomes for infants and their families.AIM To identify and analyze primary factors influencing parental involvement in their child’s care in a neonatal intensive care unit(NICU).METHODS A literature search was conducted using the PubMed,MEDLINE,and Cochrane Library for systematic reviews databases,with the following search terms:“parental presence neonatology”,“couplet care”,“zero separation neonatal care”,“family integrated care”,“couplet care intervention”,“mother-child separation”,“parents newborn togetherness”,“mother-baby care”,“closeness and separation NICU”,“mother-infant interaction NICU”,“kangaroo care”,“dyad mother-infant”,and“newborn integrated care”.The database search for this literature review began on December 10,2024,with the final search conducted on April 10,2025.RESULTS The literature search yielded 281 articles,out of which 23 were selected for a detailed review.The factors associated with parental presence in NUs were grouped into five main categories:Parents’socio-demographic and cultural traits;the physical layout and care model of the NUs;the quality of parents’relationships with the healthcare staff;their active involvement in neonatal care;and the newborn’s health status.CONCLUSION The identification of factors that affect parental presence in NUs is critical for developing effective strategies aimed at encouraging increased parental involvement and ultimately improving neonatal and family outcomes.展开更多
The rise of the aging population parallels the rapidly increasing cases of neurological disorders. This puts pressure on scientists and physicians to find novel methods that can prevent and treat neurodegeneration. Th...The rise of the aging population parallels the rapidly increasing cases of neurological disorders. This puts pressure on scientists and physicians to find novel methods that can prevent and treat neurodegeneration. The brain is made up of a complex network of different cell types that work in tandem to maintain systemic homeostasis.展开更多
BACKGROUND Living donor kidney transplantation is the optimal method of long-term renal replacement therapy.Minimally invasive donor nephrectomy techniques,such as robot-assisted(RALDN)and hand-assisted(HALDN)laparosc...BACKGROUND Living donor kidney transplantation is the optimal method of long-term renal replacement therapy.Minimally invasive donor nephrectomy techniques,such as robot-assisted(RALDN)and hand-assisted(HALDN)laparoscopic procedures,are well-established in high-income countries and are being increasingly adopted worldwide.Nevertheless,no studies have reported surgical outcomes of RALDN donor nephrectomy from a United Kingdom center to date.AIM To compare surgical outcomes between RALDN and HALDN laparoscopic donor nephrectomy in a United Kingdom high-volume living kidney donor transplant program.METHODS A case-control matching analysis was performed based on the following parameters:Sex,age,body mass index,procedure laterality,number of renal arteries,and previous abdominal surgeries.Key surgical outcomes,including primary warm ischemia time,operative duration,and post-operative recovery,were evaluated.RESULTS In this cohort of 140 living donors(70 RALDN vs 70 HALDN),donor and recipient outcomes were equivalent across key metrics:Pain scores,overall complication rates,readmissions,reoperations,and creatinine levels at 30 days and 1 year.Recipient long-term renal function did not differ between groups.Operative time for RALDN decreased significantly over the study period,indicating progressive improvement along the learning curve.Although RALDN was associated with a modestly longer mean warm ischaemia time(3.53 minutes vs 2.76 minutes,P<0.001)and extended hospital stay(4.21 days vs 3.17 days,P<0.001),these did not translate into any disadvantage in clinical outcomes.CONCLUSION In this first United Kingdom comparative cohort,RALDN demonstrated excellent safety and efficacy,even in the early phase of our programme,matching the outcomes of the well-established,gold-standard HALDN approach.Moreover,the pronounced learning-curve trajectory suggests considerable potential for further improvements in robotic surgical outcomes as the programme matures.展开更多
A remote antenna unit （RAU） selection model is presented, and two kinds of handoffs, intra-cell handoff （HO） and inter-cell HO, are defined in distributed mobile communications systems （DAS）. After that, an inte...A remote antenna unit （RAU） selection model is presented, and two kinds of handoffs, intra-cell handoff （HO） and inter-cell HO, are defined in distributed mobile communications systems （DAS）. After that, an inter-cell HO model is proposed, in which the average power of the active set （AS） is used to predict the position of the mobile station （MS）. The total power of the AS and the handoff set （HOS） are utilized to determine whether an inter-cell HO is necessary. Furthermore, the relationship between HO parameters and performance metrics is studied in detail based on RAU selection. Simulation results show that both the intra-cell HO and the inter-cell HO can achieve oerfect performance by aoprooriate settings of HO parameters.展开更多
Using the characteristic of addition of information quantity and the principle of equivalence of information quantity, this paper derives the general conversion formulae of the formation theory method conversion (synt...Using the characteristic of addition of information quantity and the principle of equivalence of information quantity, this paper derives the general conversion formulae of the formation theory method conversion (synthesis) on the systems consisting of different success failure model units. According to the fundamental method of the unit reliability assessment, the general models of system reliability approximate lower limits are given. Finally, this paper analyses the application of the assessment method by examples, the assessment results are neither conservative nor radical and very satisfactory. The assessment method can be popularized to the systems which have fixed reliability structural models.展开更多
In the process of designing self-elevating drilling unit, it is important, yet complicated, to use comparison and filtering to select the optimum scheme from the feasible ones. In this research, an index system and me...In the process of designing self-elevating drilling unit, it is important, yet complicated, to use comparison and filtering to select the optimum scheme from the feasible ones. In this research, an index system and methodology for the evaluation of self-elevating drilling unit was proposed. Based on this, a multi-objective combinatorial optimization model was developed, using the improved grey relation Analysis （GRA）, in which the analytic hierarchy process （AHP） was used to determine the weights of the evaluating indices. It considered the connections within the indices, reflecting the objective nature of things, and also considered the subjective interests of ship owners and the needs of designers. The evaluation index system and evaluation method can be used in the selection of an optimal scheme and advanced assessment. A case study shows the index system and evaluation method are scientific, reasonable, and easy to put into practice. At the same time, such an evaluation index system and evaluation method will be helpful for making decisions for other mobile platforms.展开更多
Let k=Q((D 2+md)(D 2+nd)(D 2+rd)), this paper proves firstly that the fundamental unit of k is ε=((D 2+md)(D 2+nd)+D 2(D 2+rd)) 2/(|mn|d 2), where D,d,m,n, and r are rational integers satisfying certain cond...Let k=Q((D 2+md)(D 2+nd)(D 2+rd)), this paper proves firstly that the fundamental unit of k is ε=((D 2+md)(D 2+nd)+D 2(D 2+rd)) 2/(|mn|d 2), where D,d,m,n, and r are rational integers satisfying certain conditions. Consequently, we describe the fundamental unit system of K=Q(D 2+md,D 2+nd,D 2+rd) explicitly by the fundamental unit of all the quadratic subfields and the class number h K explicitly by the class numbers of all the quadratic subfields. We also provide the fundamental unit system of some fields of (2,2) type.展开更多
In the optimal maintenance modeling, all possible maintenance activities and their corresponding probabilities play a key role in modeling. For a system with multiple non-identical units, its maintenance requirements ...In the optimal maintenance modeling, all possible maintenance activities and their corresponding probabilities play a key role in modeling. For a system with multiple non-identical units, its maintenance requirements are very complicated, and it is time-consuming, even omission may occur when enumerating them with various combinations of units and even with different maintenance actions for them. Deterioration state space partition (DSSP) method is an efficient approach to analyze all possible maintenance requirements at each maintenance decision point and deduce their corresponding probabilities for maintenance modeling of multi-unit systems. In this paper, an extended DSSP method is developed for systems with multiple non-identical units considering opportunistic, preventive and corrective maintenance activities for each unit. In this method, different maintenance types are distinguished in each maintenance requirement. A new representation of the possible maintenance requirements and their corresponding probabilities is derived according to the partition results based on the joint probability density function of the maintained system deterioration state. Furthermore, focusing on a two-unit system with a non-periodical inspected condition-based opportunistic preventive-maintenance strategy;a long-term average cost model is established using the proposed method to determine its optimal maintenance parameters jointly, in which “hard failure” and non-negligible maintenance time are considered. Numerical experiments indicate that the extended DSSP method is valid for opportunistic maintenance modeling of multi-unit systems.展开更多
Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit(HDU),and the contacting between the robot foot end and the ground is complex and variable,which increases the difficulty of force con...Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit(HDU),and the contacting between the robot foot end and the ground is complex and variable,which increases the difficulty of force control inevitably.In the recent years,although many scholars researched some control methods such as disturbance rejection control,parameter self-adaptive control,impedance control and so on,to improve the force control performance of HDU,the robustness of the force control still needs improving.Therefore,how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper.The force control system mathematic model of HDU is established by the mechanism modeling method,and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived,considering the dynamic characteristics of the load stiffness and the load damping under different environment structures.Then,simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform,which provides the foundation for the force control compensation experiment research.In addition,the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping,under which the force control compensation method is introduced,and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment.The research results indicate that if the load characteristics are known,the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation,i.e.,this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters,thereby,the online PID parameters tuning control method which is complex needs not be adopted.All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.展开更多
The reliability assessment of unit-system near two levels is the mostimportant content in the reliability multi-level synthesis of complex systems. Introducing theinformation theory into system reliability assessment,...The reliability assessment of unit-system near two levels is the mostimportant content in the reliability multi-level synthesis of complex systems. Introducing theinformation theory into system reliability assessment, using the addible characteristic ofinformation quantity and the principle of equivalence of information quantity, an entropy method ofdata information conversion is presented for the system consisted of identical exponential units.The basic conversion formulae of entropy method of unit test data are derived based on the principleof information quantity equivalence. The general models of entropy method synthesis assessment forsystem reliability approximate lower limits are established according to the fundamental principleof the unit reliability assessment. The applications of the entropy method are discussed by way ofpractical examples. Compared with the traditional methods, the entropy method is found to be validand practicable and the assessment results are very satisfactory.展开更多
The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression...The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio.Moreover,the following influential factors have been taken into account:evaporation temperature,condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor.The following quantities have been selected as the unit performance measurement indicators:refrigeration capacity,energy efficiency ratio(COP),compressor power consumption,and refrigerant flow rate.The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature,increase of condensation temperature,and increase in pressure ratio.The refrigerant flow rate increases with the increase in evaporation temperature,decrease in condensing temperature and increase in pressure ratio.The compressor power consumption increases with the increase in condensing temperature and increase in pressure ratio,but is not significantly affected by the evaporation temperature.展开更多
The concept of the glial-vascular unit(GVU)was raised recently to emphasize the close associations between brain cells and cerebral vessels,and their coordinated reactions to diverse neurological insults from a“glio-...The concept of the glial-vascular unit(GVU)was raised recently to emphasize the close associations between brain cells and cerebral vessels,and their coordinated reactions to diverse neurological insults from a“glio-centric”view.GVU is a multicellular structure composed of glial cells,perivascular cells,and perivascular space.Each component is closely linked,collectively forming the GVU.The central roles of glial and perivascular cells and their multi-level interconnections in the GVU under normal conditions and in central nervous system(CNS)disorders have not been elucidated in detail.Here,we comprehensively review the intensive interactions between glial cells and perivascular cells in the niche of perivascular space,which take part in the modulation of cerebral blood flow and angiogenesis,formation of the blood-brain barrier,and clearance of neurotoxic wastes.Next,we discuss dysfunctions of the GVU in various neurological diseases,including ischemic stroke,spinal cord injury,Alzheimer’s disease,and major depression disorder.In addition,we highlight the possible therapies targeting the GVU,which may have potential clinical applications.展开更多
基金supported by the National Natural Science Foundation of China(6090400271201166)
文摘An opportunistic maintenance model is presented for a continuously deteriorating series system with economical de-pendence. The system consists of two kinds of units, which are respectively subjected to the deterioration failure described by Gamma process and the random failure described by Poisson process. A two-level opportunistic policy defined by three decision parameters is proposed to coordinate the different maintenance actions and minimize the long-run maintenance cost rate of the system. A computable expression of the average cost rate is established by using the renewal property of the stochastic process of the maintained system state. The optimal values of three deci- sion parameters are derived by an iteration approach based on the characteristic of Gamma process. The behavior of the proposed policy is illustrated through a numerical experiment. Comparative study with the widely used corrective maintenance policy demonstrates the advantage of the proposed opportunistic maintenance method in significantly reducing the maintenance cost. Simultane- ously, the applicable area of this opportunistic model is discussed by the sensitivity analysis of the set-up cost and random failure rate.
文摘Modular unit systems provide an eco-friendly advanced construction method that improves productivity and reduces carbon emissions and construction waste. In these systems, the prefabrication ratio of the modules should be high in order to support these eco-friendly features. The purpose of this study was to verify the functionality and driving safety of fixing a modular unit with a high prefabrication ratio to a vehicle for transportation to the site using two novel adapter blocks specially developed for this purpose. When asked to evaluate their performance for this study, the truck drivers selected adaptor block type B as providing the highest convenience and functionality. In real-world driving experiments, maximum loads of 15 kN and 25 kN were measured on adapter block types A and B, respectively. Future improvements in the adapter blocks that take the safety ratio and the improved convenience of use into account are confidently expected to contribute to the eco-friendliness and the improved productivity of modular unit systems.
基金supported by the State Grid Corporation of China Science and Technology Project,grant number 52270723000900K.
文摘The new energy power generation is becoming increasingly important in the power system.Such as photovoltaic power generation has become a research hotspot,however,due to the characteristics of light radiation changes,photovoltaic power generation is unstable and random,resulting in a low utilization rate and directly affecting the stability of the power grid.To solve this problem,this paper proposes a coordinated control strategy for a newenergy power generation system with a hybrid energy storage unit based on the lithium iron phosphate-supercapacitor hybrid energy storage unit.Firstly,the variational mode decomposition algorithm is used to separate the high and low frequencies of the power signal,which is conducive to the rapid and accurate suppression of the power fluctuation of the energy storage system.Secondly,the fuzzy control algorithm is introduced to balance the power between energy storage.In this paper,the actual data is used for simulation,and the simulation results show that the strategy realizes the effective suppression of the bus voltage fluctuation and the accurate control of the internal state of the energy storage unit,effectively avoiding problems such as overshoot and over-discharge,and can significantly improve the stability of the photovoltaic power generation systemand the stability of the Direct Current bus.It is of great significance to promote the development of collaborative control technology for photovoltaic hybrid energy storage units.
基金supported by the National Natural Science Foundation of China(Project No.52377082)the Scientific Research Program of Jilin Provincial Department of Education(Project No.JJKH20230123KJ).
文摘Large-scale new energy grid connection leads to the weakening of the system frequency regulation capability,and the system frequency stability is facing unprecedented challenges.In order to solve rapid frequency fluctuation caused by new energy units,this paper proposes a new energy power system frequency regulation strategy with multiple units including the doubly-fed pumped storage unit(DFPSU).Firstly,based on the model predictive control(MPC)theory,the state space equations are established by considering the operating characteristics of the units and the dynamic behavior of the system;secondly,the proportional-differential control link is introduced to minimize the frequency deviation to further optimize the frequency modulation(FM)output of the DFPSU and inhibit the rapid fluctuation of the frequency;lastly,it is verified on theMatlab/Simulink simulation platform,and the results show that the model predictive control with proportional-differential control link can further release the FM potential of the DFPSU,increase the depth of its FM,effectively reduce the frequency deviation of the system and its rate of change,realize the optimization of the active output of the DFPSU and that of other units,and improve the frequency response capability of the system.
文摘BACKGROUND Prolonged immobility during intensive care unit(ICU)admission has been a cause of muscle atrophy and worsening functional outcomes with longer recovery times.Prior research has demonstrated that mobilization within a week of ICU admission potentially benefits physical function in critically ill patients.AIM To evaluate the effects of initiating mobilization within 72 hours of ICU admission in critically ill patients through an updated systematic review and meta-analysis.METHODS A systematic search was performed through MEDLINE,Scopus,and Cochrane Library from inception until September 2024 for randomized controlled trials(RCTs)comparing early mobilization(EM)with usual or conventional care in critically ill adult patients.Primary outcomes included length of ICU(days)and ventilation duration(days).Secondary outcomes included muscle strength,functional status,adverse events,all-cause mortality,and quality of life(QOL).A random effects meta-analysis was performed for pooled effect estimates and to derive risk ratios(RR)and corresponding 95%confidence intervals(CI).RESULTS Out of 3487 results,16 RCTs were included with a population of 2385 patients(1195 receiving EM and 1190 with usual care.)A significant reduction in the length of ICU stays[mean difference(MD)=-1.02,95%CI:-1.96 to-0.09;P=0.03;I2=60%]and ventilation duration(MD=-1.07,95%CI:-1.91 to-0.23,P=0.01;I2=57%)was observed in the EM group compared to usual care.EM significantly improved muscle strength[standard MD(SMD)=0.47,95%CI:0.18-0.75,P=0.001;I2=79%]and functional status(SMD=0.70,95%CI:0.40-1.00,P<0.00001;I2=81%)in ICU patients.No statistically significant difference was observed in adverse events(RR=1.72,95%CI:1.01-2.94,P=0.05;I2=31%),all-cause mortality(RR=1.10,95%CI:0.79-1.53,P=0.57;I2=30%),and QOL(SMD=0.04,95%CI:-0.07-0.15,P=0.50;I2=9%)between the two groups.CONCLUSION Initiating mobilization within 72 hours of ICU admission is associated with improved functional outcomes and reduced ICU length of stay and ventilation duration.These findings indicate that EM may be a safe option for ICU patients,contributing to lower recovery times and healthcare costs.Further extensive research is required to validate the long-term effects on survival and QOL.
文摘Cultural rights are important human rights established by the Universal Declaration of Human Rights(UDHR)and the International Covenant on Economic,Social and Cultural Rights(ICESCR).However,they have not received due attention within the United Nations human rights system and related academic research.As a specialized agency within the United Nations system primarily responsible for cultural affairs,United Nations Educational,Scientific and Cultural Organization(UNESCO)has played a significant role in promoting the recognition and advocacy of cultural rights in the international community,mainly by expanding and deepening the normative connotations of cultural rights,strengthening the integration of culture and cultural rights with the United Nations’development agenda,and creating cultural heritage rights and other specific examples of protection practices.Under its leadership,the United Nations system is exploring a new agenda of collective actions to promote cultural rights,which shows a trend of emphasizing cross-sectoral collaboration between culture and science,as well as culture and education.Guided by Xi Jinping Thought on Culture,China should further leverage the advantages of UNESCO as a global cultural governance platform to share its concepts and experience in protecting and realizing cultural rights with the international community.Through the Global Civilization Initiative,China can lead and shape the emerging international agenda on cultural rights and promote the progress of international human rights and the building of a community with a shared future for mankind.
基金partially supported by Korea Electrotechnology Research Institute(KERI)Primary research program through the National Research Council of Science&Technology(NST)funded by the Ministry of Science and ICT(MSIT)(No.25A01038)partially supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00218377).
文摘In this paper,a strength-constrained unit commitment(UC)model incorporating system strength constraints based on the weighted short-circuit ratio(WSCR)is proposed.This model facilitates the comprehensive assessment of area-wide system strength in power systems with high inverter-based resource(IBR)penetration,thereby contributing to the mitigation of weak grid issues.Unlike traditional models,this approach considers the interactions among multiple IBRs.The UC problem is initially formulated as a mixed-integer nonlinear programming(MINLP)model,reflecting WSCR and bus impedance matrix modification constraints.To enhance computational tractability,the model is transformed into a mixed-integer linear programming(MILP)form.The effectiveness of the proposed approach is validated through simulations on the IEEE 5-bus,IEEE 39-bus,and a modified Korean power system,demonstrating the ability of the proposed UC model enhancing system strength compared to the conventional methodologies.
文摘BACKGROUND Systemic lupus erythematosus(SLE)patients are admitted to the intensive care unit(ICU)for disease flares and infections,both of which carry a high mortality risk.Studies characterizing the outcome predictors of SLE are few in the Asian continent.This study characterized the clinical profile,treatment,and outcome predictors of ICU admissions with SLE.AIM To ascertain the reasons for ICU admission among SLE patients and to explore outcome predictors in these patients.The primary outcome was ICU mortality.Secondary outcomes included need for ventilation,inotropes,renal replacement therapy,and length of ICU and hospital stay.METHODS A retrospective study of 77 SLE patients was conducted in the medical ICU of a tertiary care teaching hospital in India.Clinical features,treatment,and outcomes of patients admitted between January 2018 and December 2022 were recorded.Factors associated with mortality were explored using bivariate and multivariate logistic regression analysis and reported as adjusted odds ratios with 95%confidence intervals.RESULTS The mean(SD)age was 31.1(10.3)years;83.1%were female.The median(interquartile)duration of SLE before admission was 12(1-60)months;SLE was newly diagnosed in the current admission in 23.4%.The median Acute Physiology and Chronic Health Evaluation II score was 16.3(14.5-18.2)and similar among survivors and nonsurvivors;32 had evidence of disease flare,44 had an infection,and one patient had an intracranial bleed.ICU admission was for respiratory failure(46.7%),hemodynamic instability(32.5%),and status epilepticus(14.3%).Twenty-nine patients(37.7%)had autoimmune hemolytic anemia,and 11(14.3%)had diffuse alveolar hemorrhage.Immunomodulation included corticosteroids(96.1%),cyclophosphamide(33.8%),mycophenolate(23.4%),plasma exchange(13%),and immunoglobulins(11.7%).All patients received broad-spectrum antibiotics.Respiratory support,inotropes,and renal replacement therapy were required in 93.5%,51.7%,and 32.5%,respectively.ICU mortality was 50.7%(95%confidence interval:39%-62%).The mean±SD hospital length of stay was 18.9±14.3 days.On multivariate analysis,only shock(P=0.004)was independently associated with mortality.CONCLUSION Intercurrent infection and disease flare are common reasons for ICU admission in SLE patients.Despite multimodal therapy,mortality is high.Shock was independently associated with mortality.
文摘BACKGROUND Parental presence in neonatal units(NUs)is essential for infant development and family well-being.A deeper understanding of the factors influencing parental presence is vital and will contribute to the development of targeted interventions and policies that enhance parental engagement in neonatal care,thereby improving outcomes for infants and their families.AIM To identify and analyze primary factors influencing parental involvement in their child’s care in a neonatal intensive care unit(NICU).METHODS A literature search was conducted using the PubMed,MEDLINE,and Cochrane Library for systematic reviews databases,with the following search terms:“parental presence neonatology”,“couplet care”,“zero separation neonatal care”,“family integrated care”,“couplet care intervention”,“mother-child separation”,“parents newborn togetherness”,“mother-baby care”,“closeness and separation NICU”,“mother-infant interaction NICU”,“kangaroo care”,“dyad mother-infant”,and“newborn integrated care”.The database search for this literature review began on December 10,2024,with the final search conducted on April 10,2025.RESULTS The literature search yielded 281 articles,out of which 23 were selected for a detailed review.The factors associated with parental presence in NUs were grouped into five main categories:Parents’socio-demographic and cultural traits;the physical layout and care model of the NUs;the quality of parents’relationships with the healthcare staff;their active involvement in neonatal care;and the newborn’s health status.CONCLUSION The identification of factors that affect parental presence in NUs is critical for developing effective strategies aimed at encouraging increased parental involvement and ultimately improving neonatal and family outcomes.
文摘The rise of the aging population parallels the rapidly increasing cases of neurological disorders. This puts pressure on scientists and physicians to find novel methods that can prevent and treat neurodegeneration. The brain is made up of a complex network of different cell types that work in tandem to maintain systemic homeostasis.
文摘BACKGROUND Living donor kidney transplantation is the optimal method of long-term renal replacement therapy.Minimally invasive donor nephrectomy techniques,such as robot-assisted(RALDN)and hand-assisted(HALDN)laparoscopic procedures,are well-established in high-income countries and are being increasingly adopted worldwide.Nevertheless,no studies have reported surgical outcomes of RALDN donor nephrectomy from a United Kingdom center to date.AIM To compare surgical outcomes between RALDN and HALDN laparoscopic donor nephrectomy in a United Kingdom high-volume living kidney donor transplant program.METHODS A case-control matching analysis was performed based on the following parameters:Sex,age,body mass index,procedure laterality,number of renal arteries,and previous abdominal surgeries.Key surgical outcomes,including primary warm ischemia time,operative duration,and post-operative recovery,were evaluated.RESULTS In this cohort of 140 living donors(70 RALDN vs 70 HALDN),donor and recipient outcomes were equivalent across key metrics:Pain scores,overall complication rates,readmissions,reoperations,and creatinine levels at 30 days and 1 year.Recipient long-term renal function did not differ between groups.Operative time for RALDN decreased significantly over the study period,indicating progressive improvement along the learning curve.Although RALDN was associated with a modestly longer mean warm ischaemia time(3.53 minutes vs 2.76 minutes,P<0.001)and extended hospital stay(4.21 days vs 3.17 days,P<0.001),these did not translate into any disadvantage in clinical outcomes.CONCLUSION In this first United Kingdom comparative cohort,RALDN demonstrated excellent safety and efficacy,even in the early phase of our programme,matching the outcomes of the well-established,gold-standard HALDN approach.Moreover,the pronounced learning-curve trajectory suggests considerable potential for further improvements in robotic surgical outcomes as the programme matures.
基金The National Natural Science Foundation of China(No60496311)
文摘A remote antenna unit （RAU） selection model is presented, and two kinds of handoffs, intra-cell handoff （HO） and inter-cell HO, are defined in distributed mobile communications systems （DAS）. After that, an inter-cell HO model is proposed, in which the average power of the active set （AS） is used to predict the position of the mobile station （MS）. The total power of the AS and the handoff set （HOS） are utilized to determine whether an inter-cell HO is necessary. Furthermore, the relationship between HO parameters and performance metrics is studied in detail based on RAU selection. Simulation results show that both the intra-cell HO and the inter-cell HO can achieve oerfect performance by aoprooriate settings of HO parameters.
文摘Using the characteristic of addition of information quantity and the principle of equivalence of information quantity, this paper derives the general conversion formulae of the formation theory method conversion (synthesis) on the systems consisting of different success failure model units. According to the fundamental method of the unit reliability assessment, the general models of system reliability approximate lower limits are given. Finally, this paper analyses the application of the assessment method by examples, the assessment results are neither conservative nor radical and very satisfactory. The assessment method can be popularized to the systems which have fixed reliability structural models.
基金Supported by the National 863 Plan Foundation under Grant No.2003AA414060
文摘In the process of designing self-elevating drilling unit, it is important, yet complicated, to use comparison and filtering to select the optimum scheme from the feasible ones. In this research, an index system and methodology for the evaluation of self-elevating drilling unit was proposed. Based on this, a multi-objective combinatorial optimization model was developed, using the improved grey relation Analysis （GRA）, in which the analytic hierarchy process （AHP） was used to determine the weights of the evaluating indices. It considered the connections within the indices, reflecting the objective nature of things, and also considered the subjective interests of ship owners and the needs of designers. The evaluation index system and evaluation method can be used in the selection of an optimal scheme and advanced assessment. A case study shows the index system and evaluation method are scientific, reasonable, and easy to put into practice. At the same time, such an evaluation index system and evaluation method will be helpful for making decisions for other mobile platforms.
文摘Let k=Q((D 2+md)(D 2+nd)(D 2+rd)), this paper proves firstly that the fundamental unit of k is ε=((D 2+md)(D 2+nd)+D 2(D 2+rd)) 2/(|mn|d 2), where D,d,m,n, and r are rational integers satisfying certain conditions. Consequently, we describe the fundamental unit system of K=Q(D 2+md,D 2+nd,D 2+rd) explicitly by the fundamental unit of all the quadratic subfields and the class number h K explicitly by the class numbers of all the quadratic subfields. We also provide the fundamental unit system of some fields of (2,2) type.
文摘In the optimal maintenance modeling, all possible maintenance activities and their corresponding probabilities play a key role in modeling. For a system with multiple non-identical units, its maintenance requirements are very complicated, and it is time-consuming, even omission may occur when enumerating them with various combinations of units and even with different maintenance actions for them. Deterioration state space partition (DSSP) method is an efficient approach to analyze all possible maintenance requirements at each maintenance decision point and deduce their corresponding probabilities for maintenance modeling of multi-unit systems. In this paper, an extended DSSP method is developed for systems with multiple non-identical units considering opportunistic, preventive and corrective maintenance activities for each unit. In this method, different maintenance types are distinguished in each maintenance requirement. A new representation of the possible maintenance requirements and their corresponding probabilities is derived according to the partition results based on the joint probability density function of the maintained system deterioration state. Furthermore, focusing on a two-unit system with a non-periodical inspected condition-based opportunistic preventive-maintenance strategy;a long-term average cost model is established using the proposed method to determine its optimal maintenance parameters jointly, in which “hard failure” and non-negligible maintenance time are considered. Numerical experiments indicate that the extended DSSP method is valid for opportunistic maintenance modeling of multi-unit systems.
基金Supported by National Key Basic Research Program of China(973 Program,Grant No.2014CB046405)State Key Laboratory of Fluid Power and Mechatronic Systems(Zhejiang University)Open Fund Project(Grant No.GZKF-201502)Hebei Military and Civilian Industry Development Funds Projects of China(Grant No.2015B060)
文摘Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit(HDU),and the contacting between the robot foot end and the ground is complex and variable,which increases the difficulty of force control inevitably.In the recent years,although many scholars researched some control methods such as disturbance rejection control,parameter self-adaptive control,impedance control and so on,to improve the force control performance of HDU,the robustness of the force control still needs improving.Therefore,how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper.The force control system mathematic model of HDU is established by the mechanism modeling method,and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived,considering the dynamic characteristics of the load stiffness and the load damping under different environment structures.Then,simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform,which provides the foundation for the force control compensation experiment research.In addition,the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping,under which the force control compensation method is introduced,and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment.The research results indicate that if the load characteristics are known,the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation,i.e.,this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters,thereby,the online PID parameters tuning control method which is complex needs not be adopted.All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.
文摘The reliability assessment of unit-system near two levels is the mostimportant content in the reliability multi-level synthesis of complex systems. Introducing theinformation theory into system reliability assessment, using the addible characteristic ofinformation quantity and the principle of equivalence of information quantity, an entropy method ofdata information conversion is presented for the system consisted of identical exponential units.The basic conversion formulae of entropy method of unit test data are derived based on the principleof information quantity equivalence. The general models of entropy method synthesis assessment forsystem reliability approximate lower limits are established according to the fundamental principleof the unit reliability assessment. The applications of the entropy method are discussed by way ofpractical examples. Compared with the traditional methods, the entropy method is found to be validand practicable and the assessment results are very satisfactory.
基金supported by the National Natural Science Foundation of China(No.41877251)the Key project of Natural Science Foundation of Tianjin City(No.6JCZDJC39000).
文摘The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio.Moreover,the following influential factors have been taken into account:evaporation temperature,condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor.The following quantities have been selected as the unit performance measurement indicators:refrigeration capacity,energy efficiency ratio(COP),compressor power consumption,and refrigerant flow rate.The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature,increase of condensation temperature,and increase in pressure ratio.The refrigerant flow rate increases with the increase in evaporation temperature,decrease in condensing temperature and increase in pressure ratio.The compressor power consumption increases with the increase in condensing temperature and increase in pressure ratio,but is not significantly affected by the evaporation temperature.
基金supported by the Ministry of Science and Technology China Brain Initiative Grant(2022ZD0204704)the National Natural Science Foundation of China(81974180)the Young Excellent Medical Scholarship of Hubei Province(2020LJRCO11).
文摘The concept of the glial-vascular unit(GVU)was raised recently to emphasize the close associations between brain cells and cerebral vessels,and their coordinated reactions to diverse neurological insults from a“glio-centric”view.GVU is a multicellular structure composed of glial cells,perivascular cells,and perivascular space.Each component is closely linked,collectively forming the GVU.The central roles of glial and perivascular cells and their multi-level interconnections in the GVU under normal conditions and in central nervous system(CNS)disorders have not been elucidated in detail.Here,we comprehensively review the intensive interactions between glial cells and perivascular cells in the niche of perivascular space,which take part in the modulation of cerebral blood flow and angiogenesis,formation of the blood-brain barrier,and clearance of neurotoxic wastes.Next,we discuss dysfunctions of the GVU in various neurological diseases,including ischemic stroke,spinal cord injury,Alzheimer’s disease,and major depression disorder.In addition,we highlight the possible therapies targeting the GVU,which may have potential clinical applications.
