Implementation of ultrasonic sensing for high resolution measurement of binary gas mixture fractions

We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10−5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions

Розробка алгоритму побудови областей сумнівних рішень для пристроїв, що містять гази у лінійному багатовимірному просторі небезпечних факторів

The issue of danger emanating from industrial devices with combustible gases has been considered in the linear multidimensional continuous space of dangerous factors. Dangerous factors are categorized into factors associated with industrial devices and the physical-chemical properties of gases that these devices contain. The actual existing combustible gases are characterized by numerical discrete properties such as molecular mass, specific heat of combustion, etc. An abstract model space of gases is represented in the space of dangerous factors by points whose coordinates are the physical-chemical properties of gases. Given the continuity of the space of dangerous factors, actual gases will be represented by individual points within this space or regions in which certain properties, for example temperature, density, volume, are continuously changing. In addition, there would be a large number of points at which the properties of gases are incompatible, that is such that are impossible for real gases. This has allowed us to consider the issue of danger emanating from combustible gases from some general positions. Thus, using the methodology of p-functions has made it possible to split the space of dangerous factors into dangerous and safe parts. It was also possible to identify the border regions in which the task of determining the hazard from a device is incorrect. That means that some variation of dangerous factors within the accuracy known about them leads to different, mutually exclusive conclusions about danger. Such areas are termed the regions of questionable decisions. It has been found that the regions of questionable decisions may be complex in shape and their size depends on the accuracy that is inherent in the quantitative values for dangerous factors. An algorithm for constructing regions of questionable decisions has been developed that could define whether a device containing gas belongs to a region of questionable decisions. It has been shown that determining whether a device is associated with a region of questionable decisions is a numerical problem with an unambiguous solutionВ линейном многомерном непрерывном пространстве опасных факторов рассмотрена проблема опасности производственных устройств с горючими газами. Опасные факторы делятся на факторы, связанные с производственными устройствами и физико-химическими свойствами газов, находящихся в этих устройствах. Реально существующие горючие газы характеризуются численными дискретными свойствами, такими как молекулярная масса, удельная теплота сгорания и т. д. Абстрактное модельное пространство газов представлено в пространстве опасных факторов точками, координаты которых являются физико-химическими свойствами газов. Вследствие непрерывности пространства опасных факторов, реальные газы будут представлены отдельными точками в этом пространстве или областями, в которых непрерывно меняются некоторые свойства, например температура, плотность, объем и т. д. Кроме этого, будет существовать большое количество точек, в которых свойства газов являются несовместными, т. е. такими, которые невозможны для реальных газов. Это позволило рассмотреть проблему опасности горючих газов с некоторых общих позиций. Используя методологию р-функций, пространство опасных факторов было разделено на опасную и безопасную части. Были выявлены пограничные области, в которых задача определения опасности устройства является некорректной. Это означает, что некоторые вариации опасных факторов в пределах точности, с которой они известны, приводит к различным, взаимоисключающим выводам об опасности. Такие области названы областями сомнительных решений. Выяснено, что области сомнительных решений могут иметь сложную форму и их обширность зависит от точности, с которой известны количественные значения опасных факторов. Разработан алгоритм построения областей сомнительных решений и определения, принадлежит ли устройство с газом области сомнительных решений. Показано, что определение, находится ли устройство в области сомнительных решений, представляет собой однозначно решаемую численную задачуУ лінійному багатовимірному безперервному просторі небезпечних факторів розглянута проблема небезпеки виробничих пристроїв з горючими газами. Небезпечні фактори поділяються на фактори, пов'язані з виробничими пристроями та фізико-хімічними властивостями газів, що знаходяться в цих пристроях. Реально існуючі горючі гази характеризуються чисельними дискретними властивостями, такими як молекулярна маса, питома теплота згоряння і т. д. Абстрактний модельний простір газів представлений в просторі небезпечних факторів точками, координати яких є фізико-хімічними властивостями газів. Внаслідок безперервності простору небезпечних факторів реальні гази будуть представлені окремими точками в цьому просторі або областями в яких безперервно змінюються деякі властивості, наприклад температура, щільність, обсяг і т. д. Крім цього, буде існувати велика кількість точок, в яких властивості газів є несумісними, тобто такими, які неможливі для реальних газів. Це дозволило розглянути проблему небезпеки горючих газів з деяких загальних позицій. Так, використовуючи методологію р-функцій, вдалося розділити простір небезпечних факторів на небезпечну і безпечні частини. Також вдалося виявити прикордонні області, в яких завдання визначення небезпеки пристрою є некоректною. Це означає, що деяка варіація небезпечних факторів в межах точності, з якої вони відомі, призводить до різних, взаємовиключних висновків про небезпеку. Такі області названі областями сумнівних рішень. З'ясовано, що області сумнівних рішень можуть мати складну форму і їх розмір залежить від точності, з якою відомі кількісні значення небезпечних факторів. Розроблено алгоритм побудови областей сумнівних рішень і визначення, чи належить пристрій з газом області сумнівних рішень. Показано, що визначення, чи знаходиться пристрій в області сумнівних рішень, являє собою чисельну задачу, що однозначно вирішуєтьс

Applications and Perspectives of Ultrasonic Multi-Gas Analysis with Simultaneous Flowmetry

International audienceWe have developed ultrasonic instrumentation to simultaneously monitor flow and composition in a variety of gas mixtures. Continuous, real-time precision measurements of the relative concentration of binary pairs of gases are required in many applications. The presence of other gases can however cause ambiguities in the measurement: a particular measured sound velocity can be the result of varying combinatorial concentrations of additional gases. We have developed an algorithm to compensate for known concentrations of additional gases, allowing the concentrations of a pair of gases of primary interest to be measured on top of a varying baseline from other known components. This algorithm uses a thermodynamic data for the contaminant gases to �deduct� their effects in multidimensional on-line databases. In our instrumentation flow and mixture composition are respectively derived from measurements of the difference and average of sound transit times in two opposite directions in a flowing process gas blend. Gas composition is then determined from an automated comparison of the measured sound velocities with a velocity/composition database of thermodynamic parameters for the gas pair of primary interest as well as for known third party gases whose concentrations in the multi-gas mixture are measured by other means. Several instruments are used in the CERN ATLAS experiment. Three monitor C3F8, (R218) and CO2 coolant leaks into N2-purged environmental envelopes. Precision in molar concentration of better than 2.10−5 is routinely seen in mixtures of C3F8 in N2 in the presence of varying known concentrations of CO2. Further instruments monitor air ingress and C3F8 vapour flow (at high massflows around 1.2 kgs-1) in a 60 kW thermosiphon C3F8 evaporative cooling recirculator. This instrumentation and analysis technique, targeting binary pairs of gases of interest in multi-gas mixtures, is promising for mixtures of anaesthetic gases, particularly in the developing area of xenon anaesthesia

Construction of an Algorithm for Building Regions of Questionable Decisions for Devices Containing Gases in a Linear Multidimensional Space of Hazardous Factors

The issue of danger emanating from industrial devices with combustible gases has been considered in the linear multidimensional continuous space of dangerous factors. Dangerous factors are categorized into factors associated with industrial devices and the physical-chemical properties of gases that these devices contain. The actual existing combustible gases are characterized by numerical discrete properties such as molecular mass, specific heat of combustion, etc. An abstract model space of gases is represented in the space of dangerous factors by points whose coordinates are the physical-chemical properties of gases. Given the continuity of the space of dangerous factors, actual gases will be represented by individual points within this space or regions in which certain properties, for example temperature, density, volume, are continuously changing. In addition, there would be a large number of points at which the properties of gases are incompatible, that is such that are impossible for real gases. This has allowed us to consider the issue of danger emanating from combustible gases from some general positions. Thus, using the methodology of p-functions has made it possible to split the space of dangerous factors into dangerous and safe parts. It was also possible to identify the border regions in which the task of determining the hazard from a device is incorrect. That means that some variation of dangerous factors within the accuracy known about them leads to different, mutually exclusive conclusions about danger. Such areas are termed the regions of questionable decisions. It has been found that the regions of questionable decisions may be complex in shape and their size depends on the accuracy that is inherent in the quantitative values for dangerous factors. An algorithm for constructing regions of questionable decisions has been developed that could define whether a device containing gas belongs to a region of questionable decisions. It has been shown that determining whether a device is associated with a region of questionable decisions is a numerical problem with an unambiguous solutio

The use of a 90 metre thermosiphon cooling plant and associated custom ultrasonic instrumentation in the cooling of the ATLAS inner silicon tracker

International audienceA new 60kW thermosiphon fluorocarbon cooling plant has been commissioned to cool the silicon tracker of the ATLAS experiment at the CERN LHC. The thermosiphon operates over a height of 90 metres and is integrated into the CERN UNICOS system and the ATLAS detector control system (DCS). The cooling system uses custom ultrasonic instrumentaton to measure very high coolant vapour flow (up to 1.2 kg/second), to analyse binary gas mixtures and detect leaks. In these instruments ultrasound pulses are transmitted in opposite directions in flowing gas streams. Pulse transit time measurements are used to calculate the flow rate and the sound velocity, which - at a given temperature and pressure - is a function of the molar concentration of the two gases. Gas composition is computed from comparisons of real-time sound velocity measurements with a database of predictions, using algorithms running in the Siemens SIMATIC WinCC SCADA environment. A highly-distributed network of five instruments is currently integrated into the ATLAS DCS. Details of the thermosiphon, its recent operation and the performance of the key ultrasonic instrumentation will be presented

Implementations of Custom Sonar Instruments for Binary Gas Mixture and Flow Analysis in the ATLAS Experiment at the CERN LHC

Precision ultrasonic measurements in binary gas systems provide continuous real-time monitoring of mixture composition and flow. Using custom microcontroller-based electronics, we have developed sonar instruments, with numerous potential applications, capable of making continuous high-precision sound velocity measurements. The instrument measures sound transit times along two opposite directions aligned parallel to - or obliquely crossing - the gas flow. The difference between the two measured times yields the gas flow rate while their average gives the sound velocity, which can be compared with sound velocity vs. molar composition look-up curves to obtain the binary mixture at a given temperature and pressure. The look-up curves may be generated from prior measurements in known mixtures of the two components, from theoretical calculations, or from a combination of the two. We describe the instruments and their performance within numerous applications in the ATLAS experiment at the CERN Large Hadron Collider (LHC). The instruments can be of interest in other areas where continuous in-situ binary gas analysis and flowmetry are required

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research