Alarm Line Research Articles

Analysis of the Runoff Component Variation Mechanisms in the Cold Region of Northeastern China under Climate Change

Climate change alters hydrological processes in cold regions. However, the mechanisms of runoff component variation remain obscure. We implemented a WEP-N model to estimate monthly runoff in the Songhua River Basin (SRB) between 1956 and 2018. All flow simulations were accurate (NSE > 0.75 and RE < 5%). The annual runoff was attenuated in 1998, and the hydrological series (1956–2018) was divided into base and change periods in that year. Relative to the BS (base scenario), annual production flow reduction was −28.2% under climate change and water use. A multifactor attribution analysis showed that climate change and water use contributed 77.0% and 23.0% to annual runoff reduction, respectively. Decreases in annual surface and base flow explained 62.1% and 35.7% of annual production flow reduction, respectively. The base flow increased by 8.5% and 6.5% during the freezing and thawing periods, respectively. Relative to the BS, groundwater recharge increased by 9.2% and 4.1% during the freezing and thawing periods, respectively, under climate change conditions. Climate change was the dominant factor attenuating production flow. The change in production flow occurred mainly during the non-freeze-thaw period. The decrease in total production flow in the SRB was caused mainly by the decrease in the surface flow, where the reduction in base flow accounted for a relatively small proportion. Production flow attenuation aggravated water shortages. The utilization rate of groundwater resources is far below the internationally recognized alarm line. Therefore, attention should be directed towards certain areas of the SRB and other regions with minimal groundwater exploitation.

Assessment on chronic and transgenerational toxicity of methamphetamine to Caenorhabditis elegans and associated aquatic risk through toxicity indicator sensitivity distribution (TISD) analysis

Evidence about the adverse effects of methamphetamine (METH) on invertebrates is scarce. Hence, C. elegans, a representative invertebrate model, was exposed to METH at environmental levels to estimate chronic and transgenerational toxicity. The results of chronic exposure were integrated into an underlying toxicity framework of METH in invertebrates (e.g., benthos) at environmentally relevant concentrations. The induction of cellular oxidative damage-induced apoptosis and fluctuation of ecologically important traits (i.e., feeding and locomotion) might be attributed by the activation of the longevity regulating pathway regulated by DAF-16/FOXO, and detoxification by CYP family enzymes. The adverse effects to the organism level included impaired viability and decreased fecundity. The results from transgenerational exposure elucidated the cumulative METH-induced damage in invertebrates. Finally, a new risk assessment method named toxicity indicator sensitivity distribution (TISD) analysis was proposed by combining multiple toxicity indicator test data (ECx) to derive the hazardous concentration for 10% indicators (C10) of one species. The risk quotient (RQ) values calculated by measured environmental concentrations and C10 in southern China, southeastern Australia, and the western US crossed the alarm line (RQ = 5), suggesting a need for long-term monitoring.

Analytical review of developments and im-provements of the working body of the cable-layer at trenchless laying of cables

The article provides an analytical review of scientific developments to improve the process of cable laying in general and specifically the working body of the cable layer in the trenchless laying of cables in different geological conditions.
 Using the patent documentation, the search and analysis of materials for the improvement of the working body of the cable layer and the main advantages of trenchless cable laying were carried out.
 The task of trenchless laying is: laying of water supply networks, sewerage, gas pipeline; laying of power supply cables, telephone and fibre-optic cable communication and alarm lines; laying on the bottom of rivers and reservoirs; laying in mountainous areas; replacement of worn-out communications with new ones.
 The article analyzes the improvement of the design of cable-laying with active earth-moving working bodies (ZRO), the principle of operation of which is based on the trenchless method, which has limited working speed and relative working speed, design complexity and low operational reliability.

Adaptive Early Warning Method Based on Similar Proportion and Probability Model

This paper presents a multi-state adaptive early warning method for mechanical equipment and proposes an adaptive dynamic update model of the equipment alarm threshold based on a similar proportion and state probability model. Based on the similarity of historical equipment, the initial thresholds of different health states of equipment can be determined. The equipment status is divided into four categories and analyzed, which can better represent its status and provide more detailed and reasonable guidance. The obtained dynamic alarm lines at all levels can regulate the operation range of equipment in the different health states. Compared to the traditional method of a fixed threshold, this method can effectively reduce the number of false alarms and attains a higher prediction accuracy, which demonstrates its effectiveness and superiority. Finally, the method was verified by means of lifetime data of a rolling bearings. The results show that the model improves the timely detection of the abnormal state of the equipment, greatly reduces the false alarm rate, and even overcomes the limitation of independence between the fixed threshold method and equipment state. Moreover, multi-state division can accurately diagnose the current equipment state, which should be considered in maintenance decision-making.

A study on stochastic degradation process models under different types of failure Thresholds

Stochastic degradation process models are developed in terms of cumulative degradation signals of systems under three types of thresholds including alarm line and two different failure thresholds. One of the failure thresholds corresponds to the degradation amount, and the other corresponds to the duration. We assume that the degradation process can be separated into two distinctive stages by a change-point which is the first passage time of the degradation process with respect to the alarm line. For simplicity, the first stage is regarded as an age-dependent (or non-stationary) Wiener process or an age-dependent (or non-stationary) Gamma process, and the second stage is regarded as an age-dependent (or non-stationary) Gamma process; thus, two special degradation models, Wiener-Gamma and Gamma-Gamma, are constructed. Specially, two-stage stationary Wiener-Gamma and Gamma-Gamma models can be viewed as special cases. The system reliability is defined as the probability that the degradation signals do not exceed a failure threshold and the duration of exceeding the alarm line is less than the duration threshold. Some reliability results including two cases in terms of duration thresholds (constants and random variables) are derived. The moments of lifetime are also given based on the results. In addition, simulation is carried out to verify the given results. And some numerical examples are presented to illustrate the results obtained in the paper.

Learning curve analysis of transapical NeoChord mitral valve repair.

Transapical off-pump mitral valve intervention with neochordae implantation is a novel, minimally invasive procedure for treatment of degenerative mitral valve regurgitation. The aim of this study was to apply control charts (CUSUM curves) to monitor the performance of NeoChord repair during the initial phase of its adoption. The first 112 consecutive patients who underwent NeoChord repair at our institution between November 2013 and March 2016 were included in the analysis. Mitral Valve Academic Research Consortium criteria for 1-year patient success was utilized to determine failed procedures. Control charts had predetermined acceptable and unacceptable failure rates of 5% and 15%, respectively. The actual incidence of 1-year-patient failure was 11% (12 of 112 cases), with a cluster of failures within the first 20 cases. The CUSUM analysis demonstrated an initial learning curve; however, the upper boundary (alarm line) was never crossed. The reassurance line was first crossed after 40 procedures and performance remained stable after 49 procedures. NeoChord repair is a safe procedure, and the results are maintained through the 1-year follow-up. A relative high number of implants were required to overcome the learning curve at our institution due to the concurrent development of patient selection criteria and the technical refinement of the procedure. Future studies are needed to assess the evolution of the learning curve after the wide adoption of the procedure across European and North American centres.

Associated bare stenting of distal aorta with a Djumbodis® system versus conventional surgery in type A aortic dissection

The effectiveness of additional stenting of the distal aorta as compared to conventional surgery alone in type A aortic dissection (TAD) has yet to be proven. We conducted this multicenter comparative study to evaluate the effects of antegrade bare stenting of the dissected aorta beyond the distal anastomosis with a Djumbodis(®) device system (DDS). Outcomes that were measured included early outcomes, overall mortality from aortic cause and late aortic events including re-interventions. A consecutive series of 134 patients operated on in two participating centers were distributed into study and control groups according to the treatment received: conventional surgery with DDS (DJ group, n=42) or without (control group, n=92). Operative mortality was 21.4% and 17.6% in the DJ and control groups, respectively (P=0.9), and was within pre-specified alarm lines for both groups. In multivariate analysis, the only independent predictor of operative mortality was the presence of any complication (cardiac tamponade or malperfusion, P=0.05), which occurred more in the DJ group (OR =1.3; non-significant). Sixty patients were included into the matched survivors cohorts study (propensity scoring). The aortic event-free survival at 7 years for early survivors was 77%±10% and 48%±11% in the matched DJ group and control group, respectively (HR =0.66). Late mortality from an aortic cause was 10% and 20% in the matched DJ group and control group, respectively (RR =0.5). Actuarial freedom from aortic or vascular interventions was 71%±10% and 67%±9% in the matched DJ and control group, respectively. Operative mortality was not influenced by the use of DDS as compared to conventional surgery alone for TAD. We observed a trend towards better organ perfusion in the DJ group postoperatively, and more aortic events and deaths of aortic cause in the control group during follow-up.

Research of alarm correlations based on static defect detection

refined semantic (line 2). As described earlier, if an alarm reported at the defect detection phase is not reported by the procedure (line 3) under the abstract refined semantic with an alarm (line 5-6), we say abstractly correlates with and is denotedly correlates with and is denoted

Whole-Condition Dynamic Alarm Research of Hydropower Unit Operating Parameters

Set the alarm value in the condition monitoring system of hydropower unit to monitor unit state parameters, if the difference between the two values exceeds the safety threshold, the alarm works, it is an effective method. Now the state parameters alarm values are set up mainly for the stable operation area in the unit condition monitoring system, which were not suit for low load conditions and in the process of load. To realize the full condition dynamic alarm of hydroelectric generating units, they are two ways: (1), build unit state parameter prediction model, compared predict values with the measured values. (2), set the alarm line, when the measured value exceeds the alarm line, the alarm works,. These two methods are considered the working condition head and output .This paper introduces several different alarm line settings, such as line alarm, partition line alarm, dynamic alarm curve and dynamic alarm surface.

Is proctoring mandatory when starting a TAVI program?

Is proctoring mandatory when starting a TAVI program?

Enhancing departmental quality control in minimally invasive mitral valve surgery: a single-institution experience

In recent years, there has been an increasing interest in monitoring the quality of cardiac surgical performance. The aim of the present study was to apply control charts (CUSUM curves) to monitor the performance of minimally invasive mitral valve procedures to enhance quality control for that operation. A total of 936 minimally invasive mitral valve procedures were performed from September 2003 to March 2011 by seven surgeons (range 26-401 procedures) at a single institution. Institutional and individual surgeons' performances were monitored using descriptive statistics and control charts, with a predetermined acceptable failure rate of 10% and calculated 80% alert and 95% alarm lines. Perioperative death or one or more of seven adverse events constituted failure. The incidence of in-hospital mortality was 1.8% (17/936) and compared favourably with the predicted mortality (logistic EuroSCORE 7.3%). Institutional CUSUM analysis revealed an initial learning curve and then the surgical process remained in control for all the study period. There were differences between surgeons with regard to the learning curves and perioperative complications (7.3-11.3%, P = 0.9). Five surgeons crossed the 95% reassurance boundary between operations 23 and 48. One surgeon crossed the 95% reassurance boundary after 116 operations. No surgeon crossed the 95% alarm line, which indicates unacceptably high failure rates. Minimally invasive mitral surgery can be safely performed with low morbidity and mortality. CUSUM curve analysis is a simple statistical method to implement continuous individual and departmental performance monitoring.

Safe Launching of a Newly Appointed Cardiac Surgery Unit at a Low-Volume Hospital With the Use of Cumulative Sum Analysis

Few studies have used the cumulative sum method to examine the initial performance of a newly appointed cardiac surgery team at a low-volume hospital. In the 4 years from April 2002 to December 2006, 274 cases of open-heart surgery were performed and the overall mortality and morbidity rates were 4.01% and 5.84%, respectively. The respective rates for coronary, valvular and aortic surgery were 2.05% and 2.74%, 3.61% and 7.23%, and 11.1% and 13.3%. The overall cumulative sum curve was below the 80% upper alarm line since the 58(th) case and below the 80% lower alarm line since the 139th case. The respective values for the cumulative sum curves of valvular and coronary surgery were the 1st and 41st cases, the 22nd and the 76th cases, but for aortic surgery the cumulative sum curve remained below the 80% upper alarm line since the 1st case but did not reach below the 80% lower alarm line An open-heart surgery unit at a low-volume hospital could compete with a high-volume hospital if it has a safe launching and low mortality and morbidity rates. The predictor of a safe launching is not the annual volume, but the cumulative experience of the surgical team.

Learning Curve of Arch-First Technique Analyzed by Cumulative Sum

This study was undertaken to verify efficacy of the arch-first technique in the light of its learning curve. From April 2002 to September 2005, 10 consecutive elective cases of total arch replacement were retrospectively examined. The learning curve of the arch-first technique was constructed using cumulative sum analysis. There were no operative deaths. The mean deep hypothermic circulatory arrest time was 28.4 +/- 13.7 min, the lower body ischemic time was 91.3 +/- 35.1 min, aortic cross clamp time was 133.2 +/- 18.1 min, cardiopulmonary bypass time was 198.8 +/- 21.5 min, and operation time was 383 +/- 24 min. The durations of deep hypothermic circulatory arrest, bypass, and operation were under the 90% lower alarm line in all 10 cases. The lower body ischemic time and cardiac arrest time were between the 80% upper and lower alert lines. Cumulative sum analysis of total arch replacement using the arch-first technique showed satisfactory rates of improvement in reconstruction of the 3 arch vessels, cardiopulmonary bypass time, and overall mortality.

Learning curve of coronary surgery by a cardiac surgeon in Japan with the use of cumulative sum analysis

Case-volume has been believed to be of paramount importance in becoming a good cardiac surgeon. However, for a training cardiac surgeon there is no evidence regarding the specific number of necessary cases to attain the medico-legally acceptable level. We attempted to observe the learning curve in performing coronary surgery with the use of the cumulative sum (CUSUM) method to provide some evidence. From April 2000 to March 2004, a cardiac surgeon, being board-certified but not being on the attending staff, performed 50 coronary artery bypass grafting (CABG) under supervision of three different chief attending surgeons at three different hospitals. His learning curve was analyzed with the use of CUSUM. Mortality and morbidity and the average time of crossclamp and operation at each hospital were examined. Also, the learning curve of 100 left internal mammary artery (LIMA) harvestings were analyzed via CUSUM in terms of harvesting time and injury rate. The CUSUM curve tended to come closer to the alert line (0.80 confidence) until the 23rd case, but never reached the alert line thereafter until the 50th case. The CUSUM curve never transgressed the alarm line (0.95 confidence) throughout 50 cases. The CUSUM curve of LIMA harvesting approached the alert line in the 38th case and the 59th case, but thereafter never reached the alert line and remained below the reassurance line from the 73rd case. Tentatively, it is inferred that approximately 23 cases of CABG may be sufficient to allow for independent practice and that 73 cases of LIMA harvesting are sufficient to allow independent practice.

Cumulative risk adjusted monitoring of 30-day mortality after cardiothoracic transplantation: UK experience

Guidelines are needed for real-time quality monitoring in heart and lung transplantation. The cumulative sum (CUSUM) methodology with boundary limits derived from the sequential probability ratio test (SPRT) provide a means of monitoring performance without the need for repeated statistical testing. The variable life adjusted display (VLAD) complements the SPRT chart and provides a directly interpretable assessment of performance. We present our experience with these charts in monitoring cardiothoracic transplant outcomes in the UK. Thirty-day-post-transplantation mortality after isolated first time transplantation of the heart (n=1634) or lung (n=1162) in adults, between July 1995 and March 2004 in eight centres were monitored. CUSUM charts, with and without risk-adjustment and risk-adjusted VLAD plots were constructed. Thirty-day mortality rates for the UK as a whole were taken as the reference values for the unadjusted charts and a 50% increase in risk provided the basis for construction of boundary lines for the SPRT. Risk-adjustment was based on multivariate models previously developed from the national database. For heart transplantation without risk-adjustment, four centres crossed the lower boundary, indicating 30-day mortality was in-line with or better than seen nationally. Two centres were close to signalling an alert, warning of a rise in mortality rate, but neither chart signalled an alarm. After risk-adjustment one centre's graph moved towards the centre of the chart, indicating monitoring should continue and the other signalled an alarm. For lung transplantation the unadjusted mortality rate at one centre was confirmed acceptable and the results remained inconclusive for five. At the other centre, following an alert to a possible increase in mortality half-way through the sequence, results improved. Case-mix adjustment served to pull the charts away from the upper boundary lines; no chart suggested any cause for concern. For most centres the VLAD charts oscillated around the horizontal axis. CUSUM charts are useful tools for monitoring performance, and provide a basis for visually comparing results between centres and identifying periods of 'bad runs'. Risk-adjustment, which down-weights higher risk activity, avoids inappropriate reaction to unadjusted breaches of alert and alarm lines.

Cumulative sum failure analysis of the learning curve with endovascular abdominal aortic aneurysm repair.

The purpose of this study was to evaluate the importance of experience and the learning curve with endovascular abdominal aortic aneurysm (AAA) repair. A retrospective analysis was performed of all elective endovascular AAA repairs attempted by an individual surgeon and radiologist over a 4-year period. The primary outcome variable was achievement and 30-day maintenance of initial clinical success as defined by the Society for Vascular Surgery/American Association of Vascular Surgery reporting standards. Following standard statistical analysis, the cumulative sum (CUSUM) method was used to analyze the learning curve, with a predetermined acceptable failure rate of 10% and calculated 80% alert and 95% alarm lines. Ninety-six elective endovascular AAA repairs were attempted by this team between 1998 and 2002 (mean age 74 +/- 0.8 years; mean aneurysm diameter 5.98 +/- 0.8 cm). Initial clinical success was achieved and maintained in 85 of 96 patients (88.5%). Although results were acceptable throughout the study period, improved results with respect to the target failure rate (10%) were not achieved until 60 patients were treated. The learning or CUSUM curves did not differ for different device manufacturers, with improved results being achieved following 20 implantations of each device. The results did differ when comparing aortouniiliac grafts (n = 27) and bifurcated grafts (n = 64). Results with bifurcated grafts remained consistent throughout the study period, whereas with aortouniiliac grafts, results improved after only a few procedures in comparison with the target failure rate. Success rates with endovascular aneurysm repair will improve with an individual's experience. The CUSUM method is a valuable tool in the evaluation of this learning curve, which has credentialing and training implications. Although acceptable results were obtained throughout the study period, this analysis indicates that 60 endovascular aneurysm repairs, or 20 with an individual device, are necessary before optimal rates of initial clinical success can be achieved. These results can be achieved more readily with aortouniiliac grafts than with bifurcated grafts.

The Learning Curve of an Academic Cardiac Surgeon: Use of the CUSUM Method

Despite the sizeable volume of research on the determinants of outcome after cardiac operations, few articles have analyzed the learning curves of individual cardiac surgeons over time. The objective of our study was to analyze statistically the learning curve of an academic cardiac surgeon in reducing operative morbidity and mortality during a 10-year interval. The study cohort of 1347 consecutive and unselected patients undergoing cardiac surgical operations from October 1988 to September 1998 were grouped into five 2-year blocks (periods 1 to 5) according to the date of operation. The main outcome measures were operative mortality rate and standardized definitions of perioperative myocardial infarction, intra-aortic balloon pump use, reoperation for bleeding, stroke, sternal wound complications, sepsis, and respiratory insufficiency. Preoperative risk factors and operative results in periods 1 to 5 were compared statistically using a chi-square test for linear trend (categorical variables) or analysis of variance with linear contrast and lack of fit tests (continuous variables). In addition, the cumulative sum (CUSUM) method was used to determine the association among operative morbidity, mortality, and prespecified 80% alert and 95% alarm boundary lines in practice years 1, 5, and 9. Of the preoperative risk factors, only patient age showed an important change during the 10 years of the study (61.3+/-0.7 to 64.3+/-0.6, p = 0.001). There were no statistically significant changes from periods 1 to 5 in overall operative mortality (4.0% to 2.2%, p = 0.56) or in the rates of perioperative stroke (1.8% to 3.8%, p = 0.33), sternal wound complications (0.4% to 0.8%, p = 0.97), sepsis (0.9% to 0.8%, p = 0.63), or respiratory failure (4.4% to 2.8%, p = 0.21). Decreases occurred in a linear fashion during periods 1 to 5 in mortality after coronary artery bypass grafting (5.1% to 1.3%, p = 0.012) and in the rates of perioperative myocardial infarction (7.0% to 2.2%, p = 0.005), intra-aortic balloon pump use (7.0% to 3.0%, p = 0.05), and reoperation for bleeding (8.4% to 2.2%, p = 0.001). The number of uneventful cases between a death or complication increased from 2.82+/-0.43 in period 1 to 6.44+/-1.10 in period 5 (p < 0.001). On CUSUM analysis, the cumulative failure rate in year 1 transgressed the upper 80% alert line after 56 cases and the upper 95% alarm line after 69 cases. During years 5 and 9 the failure rate gravitated around the 80% and 95% "reassurance" lines, respectively, indicating improved results as compared to year 1. The mortality rate after coronary artery bypass grafting and select perioperative morbidity rates improved in a linear fashion from the onset of independent practice to year 10. The CUSUM method was helpful in identifying suboptimal results during the first year of practice and shows promise as a method of prospective quality control in cardiac surgery. These data support mentorship of new consultants by a senior surgeon during the first year or two of independent practice.

Ventilator pressure alarm line adaptor for the Penlon 200 fitted with a Newton valve

Ventilator pressure alarm line adaptor for the Penlon 200 fitted with a Newton valve

The Learning Curve of an Academic Cardiac Surgeon: Use of the CUSUM Method

Abstract Background: Despite the sizeable volume of research on the determinants of outcome after cardiac operations, few articles have analyzed the learning curves of individual cardiac surgeons over time. The objective of our study was to analyze statistically the learning curve of an academic cardiac surgeon in reducing operative morbidity and mortality during a 10-year interval. Methods: The study cohort of 1347 consecutive and unselected patients undergoing cardiac surgical operations from October 1988 to September 1998 were grouped into five 2-year blocks (periods 1 to 5) according to the date of operation. The main outcome measures were operative mortality rate and standardized definitions of periopera-tive myocardial infarction, intra-aortic balloon pump use, reoperation for bleeding, stroke, sternal wound complications, sepsis, and respiratory insufficiency. Preoperative risk factors and operative results in periods 1 to 5 were compared statistically using a chi-square test for linear trend (categorical variables) or analysis of variance with linear contrast and lack of fit tests (continuous variables). In addition, the cumulative sum (CUSUM) method was used to determine the association among operative morbidity, mortality, and prespecified 80% alert and 9590 alarm boundary lines in practice years 1, 5, and 9. Results: Of the preoperative risk factors, only patient age showed an important change during the 10 years of the study (61· 3 ± 0· 7 to 64· 3 ± 0· 6, p = 0· 001). There were no statistically significant changes from periods 1 to 5 in overall operative mortality (4· 0% to 2· 2%, p = 0· 56) or in the rates of perioperative stroke (1· 8% to 3· 840, p = 0· 331, sternal wound complications (0· 496 to 0· 896, p = 0· 97), sepsis (0· 9% to 0· 856, p = 0· 631, or respiratory failure (4--4% to 2· 8Y0, p = 0· 21). Decreases occurred in a linear fashion during periods 1 to 5 in mortality after coronary artery bypass grafting (5·1% to 1·3%, p = 0·012) and in the rates of perioperative myocardial infarction (7·0% to 2·2%, p = 0·005), intra-aortic balloon pump use (7·096 to 3·0%, p = 0·051, and reoperation for bleeding (8·4% to 2·2%, p = 0·001). The number of uneventful cases between a death or complication increased from 2·82 ± 0·43 in period 1 to 6·44 ± 1·10 in period 5 (p < 0·001). On CUSUM analysis, the cumulative failure rate in year 1 transgressed the upper 80% alert line after 56 cases and the upper 95% alarm line after 69 cases. During years 5 and 9 the failure rate gravitated around the 80% and 95%“reassurance” lines, respectively, indicating improved results as compared to year 1. Conclusions: The mortality rate after coronary artery bypass grafting and select perioperative morbidity rates improved in a linear fashion from the onset of independent practice to year 10. The CUSUM method was helpful in identifying suboptimal results during the first year of practice and shows promise as a method of prospective quality control in cardiac surgery. These data support mentorship of new consultants by a senior surgeon during the first year or two of independent practice.