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20 个结果
  • 简介:InthispaperweproposeamodificationoftheLandweberiterationtermedfrozenLandweberiterationfornonlinearill-posedproblems.Aconvergenceanalysisforthisiterationispresented.ThenumericalperformanceofthisfrozenLandweberiterationforanonlinearHammersteinintegralequationiscomparedwiththatoftheLandweberiteration.WeobtainashorterrunningtimeofthefrozenLandweberiterationbasedonthesameconvergenceaccuracy.

  • 标签: 非线性不适定问题 冻结Landweber叠代 改良 收敛分析
  • 简介:Twodynamicalsystemmethodsarestudiedforsolvinglinearill-posedproblemswithbothoperatorandright-handnonexact.ThemethodssolveaCauchyproblemforalinearoperatorequationwhichpossessesaglobalsolution.Thelimitoftheglobalsolutionatinfinitysolvestheoriginallinearequation.Moreover,wealsopresentaconvergentiterativeprocessforsolvingtheCauchyproblem.

  • 标签: 动力系统 算符方程 计算数学 线性问题
  • 简介:Forill-posedbilevelprogrammingproblem,theoptimisticsolutionisalwaysthebestdecisionfortheupperlevelbutitisnotalwaysthebestchoiceforbothlevelsiftheauthorsconsiderthemodel'ssatisfactorydegreeinapplication.Toacquireamoresatisfyingsolutionthantheoptimisticonetorealizethetwolevels'mostprofits,thispaperconsidersbothlevels'satisfactorydegreeandconstructsaminimizationproblemofthetwoobjectivefunctionsbyweightedsummation.Then,usingthedualitygapofthelowerlevelasthepenaltyfunction,theauthorstransferthesetwolevelsproblemtoasingleoneandproposeacorrespondingalgorithm.Finally,theauthorsgiveanexampletoshowamoresatisfyingsolutionthantheoptimisticsolutioncanbeachievedbythisalgorithm.

  • 标签: 二层规划问题 加权求和 罚函数方法 不适定 威盛 求解
  • 简介:高一英语第五课开篇不几行有Mathilde和Jeanne这样两句对话:“Idon’tthinkIknowyou”,“Ihopeyouweren’till”。有学生问第二句可否写成“Idon’thopeyouwereill”。回答当然是否定的。以上两句的共同点是:否定词都是否定从句谓语的。不同的是:前一句否定词需置于主句谓语中,称为

  • 标签: THINK 章振邦 语法学家 SUPPOSE EXPECT assume
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  • 简介:AbstractFortheweaklyinhomogeneousacousticmediuminΩ={(x,y,z):z>0},weconsidertheinverseproblemofdeterminingthedensityfunctionρ(x,y).Theinversioninputforourinverseproblemisthewavefieldgivenonaline.Wegetanintegralequationforthe2-Ddensityperturbationfromthelinearization.Byvirtueoftheintegraltransform,weprovetheuniquenessandtheinstabilityofthesolutiontotheintegralequation.Thedegreeofill-posednessforthisproblemisalsogiven.

  • 标签: LINEARIZATION INVERSION INTEGRAL GEOMETRY ILL-POSEDNESS
  • 简介:性恶的稳定的倒置为其零动力学不可思议地被使不安的稍微非最小的阶段系统被学习,也就是说,相对的度是不清楚的。为这些系统,我们证明那在那里存在在当经由稳定的倒置的调节得好的前馈控制输入被寻求时,要追踪的一条引用轨道的带宽的固有的限制。我们断言当这限制的违背发生时,所谓的参考书轨道重新设计被叫为。如果需要,我们的分析结果能为参考书轨道重新设计提供一个明确的评价以及有用指导。

  • 标签: 动力学分析 控制理论 自动化 最佳化
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  • 简介:AbstractBackground:Glucose control is an important aspect in managing critically ill patients. The goal of this study was to compare the effects of sequential feeding (SF) and continuous feeding (CF) on the blood glucose of critically ill patients.Methods:A non-inferiority randomized controlled trial was adopted in this study. A total of 62 patients who were fed enteral nutritional suspension through gastric tubes were enrolled. After achieving 80% of the nutrition target calories (25 kcal·kg-1·day-1) through CF, the patients were then randomly assigned into SF and CF groups. In the SF group, the feeding/fasting time was reasonably determined according to the circadian rhythm of the human body as laid out in traditional Chinese medicine theory. The total daily dosage of the enteral nutritional suspension was equally distributed among three time periods of 7 to 9 o’clock, 11 to 13 o’clock, and 17 to 19 o’clock. The enteral nutritional suspension in each time period was pumped at a uniform rate within 2 h by an enteral feeding pump. In the CF group, patients received CF at a constant velocity by an enteral feeding pump throughout the study. Blood glucose values at five points (6:00/11:00/15:00/21:00/1:00) were monitored and recorded for seven consecutive days after randomization. Enteral feeding intolerance was also recorded. Non-inferiority testing was adopted in this study, the chi-square test or Fisher test was used for qualitative data, and the Mann-Whitney U test was used for quantitative data to determine differences between groups. In particular, a repeated measure one-way analysis of variance was used to identify whether changes in glucose value variables across the time points were different between the two groups.Results:There were no significant demographic or physiological differences between the SF and CF groups (P > 0.050). The average glucose level in SF was not higher than that in CF (8.8 [7.3-10.3] vs. 10.7 [9.1-12.1] mmol/L, Z = -2.079, P for non-inferiority = 0.019). Hyperglycemia incidence of each patient was more common in the CF group than that in the SF group (38.4 [19.1-63.7]% vs. 11.8 [3.0-36.7]%, Z = -2.213, P = 0.027). Hypoglycemia was not found in either group. Moreover, there was no significant difference during the 7 days in the incidence of feeding intolerance (P > 0.050).Conclusions:In this non-inferiority study, the average blood glucose in SF was not inferior to that in CF. The feeding intolerance in SF was similar to that in CF. SF may be as safe as CF for critically ill patients.

  • 标签: Intensive care unit Enteral feeding Blood glucose Feeding intolerance
  • 简介:摘要BACKGROUNDEarly physical rehabilitation in the intensive care unit (ICU) has been shown to improve short-term clinical outcomes but long-term benefit has not been proven and the optimum intensity of rehabilitation is not known.METHODSWe conducted a randomised, parallel-group, allocation- concealed,assessor-blinded, controlled trial in patients who had received at least 48 hours of invasive or non-invasive ventilation. Participants were randomised in a 1∶1 ratio, stratified by admitting ICU, admission type and level of independence. The intervention group had a target of 90 min physical rehabilitation per day, the control group a target of 30 min per day (both Monday to Friday). The primary outcome was the Physical Component Summary (PCS) measure of SF-36 at 6 months.RESULTSWe recruited 308 participants over 34 months: 150 assigned to the intervention and 158 to the control group. The intervention group received a median (IQR) of 161 (67-273) min of physical rehabilitation on ICU compared with 86 (31-139) min in the control group. At 6 months, 62 participants in the intervention group and 54 participants in the control group contributed primary outcome data. In the intervention group, 43 had died, 11 had withdrawn and 34 were lost to follow-up, while in the control group, 56 had died, 5 had withdrawn and 43 were lost to follow-up. There was no difference in the primary outcome at 6 months, mean (SD) PCS 37 (12.2) in the intervention group and 37 (11.3) in the control group.CONCLUSIONSIn this study, ICU-based physical rehabilitation did not appear to improve physical outcomes at 6 months compared with standard physical rehabilitation.

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  • 简介:AbstractBackground:It is crucial to improve the quality of care provided to ICU patient, therefore a national survey of the medical quality of intensive care units (ICUs) was conducted to analyze adherence to quality metrics and outcomes among critically ill patients in China from 2015 to 2019.Methods:This was an ICU-level study based on a 15-indicator online survey conducted in China. Considering that ICU care quality may vary between secondary and tertiary hospitals, direct standardization was adopted to compare the rates of ICU quality indicators among provinces/regions. Multivariate analysis was performed to identify potential factors for in-hospital mortality and factors related to ventilator-associated pneumonia (VAP), catheter-related bloodstream infections (CRBSIs), and catheter-associated urinary tract infections (CAUTIs).Results:From the survey, the proportions of structural indicators were 1.83% for the number of ICU inpatients relative to the total number of inpatients, 1.44% for ICU bed occupancy relative to the total inpatient bed occupancy, and 51.08% for inpatients with Acute Physiology and Chronic Health Evaluation II scores ≥15. The proportions of procedural indicators were 74.37% and 76.60% for 3-hour and 6-hour surviving sepsis campaign bundle compliance, respectively, 62.93% for microbiology detection, 58.24% for deep vein thrombosis prophylaxis, 1.49% for unplanned endotracheal extubations, 1.99% for extubated inpatients reintubated within 48 hours, 6.38% for unplanned transfer to the ICU, and 1.20% for 48-hour ICU readmission. The proportions of outcome indicators were 1.28‰ for VAP, 3.06‰ for CRBSI, 3.65‰ for CAUTI, and 10.19% for in-hospital mortality. Although the indicators varied greatly across provinces and regions, the treatment level of ICUs in China has been stable and improved based on various quality control indicators in the past 5 years. The overall mortality rate has dropped from 10.19% to approximately 8%.Conclusions:The quality indicators of medical care in China’s ICUs are heterogeneous, which is reflected in geographic disparities and grades of hospitals. This study is of great significance for improving the homogeneity of ICUs in China.

  • 标签: Medical quality ICU China Epidemiological survey