Tube Type Research Articles

Analyzing the Influence of Welding Process Selection on Residual Stresses in Tube-to-Tubesheet Welded Joints

Tube-to-tubesheet joints are used in the fabrication of shell and tube type heat exchangers, steam generators, boilers, condensers, and end shields of pressure tube type nuclear reactors like CANDU (Canada Deuterium Uranium) and PHWR (Pressurized Heavy Water Reactor). The weld joints connecting the tubes to the tubesheets are of prime importance as they have a direct impact on equipment safety. In the fabrication of these critical class-1 nuclear components, full penetration weld joints are used. Typically, these full penetration weld joints are created through multi-pass Tungsten Inert Gas (TIG) welding. However, more recent techniques, such as single-pass Electron Beam Welding (EBW) and Laser Beam Welding (LBW), have also been employed for this purpose. The fabrication time of these pieces of equipment containing full penetration weld joints can be drastically reduced if single-pass welding techniques are used compared to multi-pass welding techniques. However, the residual stresses developed in these joints due to the localized heat input and the substantial constraints of the tubesheet are unknown. Different welding processes, such as TIG welding, EBW, or LBW, can lead to varying levels of residual stresses in these joints, subsequently impacting their longevity. Weld residual stress plays a significant role in the initiation of failure modes of these tube-to-tubesheet welded joints, such as stress corrosion cracking, fatigue, and corrosion fatigue.This paper analyzes the residual stresses developed at the tube-to-tubesheet interface resulting from different welding techniques, such as multi-pass TIG welding and single-pass EBW/LBW. A comprehensive three-dimensional coupled thermo-mechanical finite element analysis is employed for this purpose. The findings reveal a significant difference, with single-pass EBW exhibiting up to 32% lower residual stresses compared to multi-pass TIG welding. Additionally, the Heat Affected Zone (HAZ) in EBW is approximately 50% smaller than in TIG welding, and the equivalent distortion in EBW is reduced by 90% compared to multi-pass TIG welding. In summary, this investigation concludes that single-pass EBW offers distinct advantages for tube-to-tubesheet weld joints, including reduced residual stresses, a smaller HAZ, and lower distortions.

Association of time to start of enteral nutrition and outcome in cats with hepatic lipidosis.

Enteral nutrition (EN) is essential for management of hepatic lipidosis (HL) in cats. To determine if time to start of EN and other clinicopathologic variables are associated with outcome in cats with HL. Forty-eight cats with HL. Retrospective study. Information retrieved from medical records and client communications included clinicopathologic findings, time to start of EN, initial % of resting energy requirements provided, type of feeding tube, duration of hospitalization, and 3-month survival. Variables were compared between surviving and nonsurviving cats and between cats fed ≤12 hours and >12 hours after hospital admission. Multivariable statistical testing was performed to further investigate variables of interest. Seventeen of 25 (68%) cats fed ≤12 hours and 13 of 23 (57%) of cats fed >12 hours after hospital admission survived (P = .55). Only increasing age (odds ratio [OR], 1.313; 95% confidence interval [CI], 1.032-1.671; P = .03) and the presence of ascites (OR, 6.415; 95% CI, 1.354-30.395; P = .02) were associated with death in multivariable analysis. Hospitalization duration (median, interquartile range [IQR]) was shorter in cats fed >12 hours (2.8 days; IQR, 2.1-3.8 days) as compared with cats fed ≤12 hours (4.8 days; IQR, 3.6-6.2 days) after hospital admission (P < .001). An initial stabilization period before EN introduction does not decrease survival or increase duration of hospitalization in cats with HL.

Features of nutrition and care of patients with jejunostomy

Introduction. A common type of palliative intervention is the imposition of nutritional fistulas for enteral nutrition in dysphagia. The operation of choice is gastrostomy, in which the gastric stage of digestion is preserved. This is more physiological and reduces the risk of developing dumping syndrome and metabolic disorders that can develop with the introduction of nutrition into the jejunum directly. Ejunostomy is applied when gastrostomy is technically impossible due to damage to the stomach, or as a stage in another operation. The infrequent use of jejunostomy leads to a lack of awareness among medical professionals about the specifics of care and nutrition through jejunostomy, which differ significantly from the standard recommendations for gastrostomy. The aim is to study. Offer advice on care and nutrition through the jejunostomy. Materials and Methods. The recommendations are based on literature data and the clinical experience of the authors who perform these operations, teach patients and their relatives care, nutrition through the jejunostomy, and manage these patients at the outpatient stage. The results and their discussion. The article provides recommendations for the care of jejunostomy, depending on the type of jejunostomy and feeding tube. The technique of feeding through the jejunostomy is described in the details, while an original method for the slow introduction of the nutrient mixture in the absence of special systems for drip nutrition is proposed. General recommendations on the selection of a nutrient mixture for feeding through the jejunostomy are given. Conclusion. Fistula care and feeding of patients with jejunostomy are differ from similar activities carried out in patients with gastrostomy. The proposed article will improve the orientation of medical workers in the problem and may serve as the beginning of the development of domestic recommendations for the care of the fistula and nutrition of patients with jejunostomy.

Discrepancies of bovine haptoglobin concentrations between serum and plasma using two different anticoagulants and a colorimetric assay based on peroxidase activity.

Haptoglobin (Hp) is an emerging diagnostic marker in cattle, and knowledge of suitable sample types and measurement methods is important. The aims of this study were to compare the results of a colorimetric assay (CA) and an ELISA for bovine Hp using serum, EDTA plasma, and lithium-heparinized (LH) plasma, respectively, and to assess the diagnostic potential for puerperal metritis. In experiment 1, Hp was measured in pooled aliquots of serum (n = 10), EDTA plasma (n = 10), and LH plasma (n = 10) of 100 healthy fresh lactating dairy cows from 10 farms using both the CA and the ELISA. In experiment 2, five healthy and five cows with acute puerperal metritis were sampled, and Hp was determined using both assays for all three sample types. In experiment 3, aliquots of serum and LH plasma from cows in different lactation stages were transferred into plain, EDTA-coated, and LH-coated tubes and mixed before colorimetric analyses. Distilled water was also placed into each tube type and treated similarly. Plasma samples measured with the CA showed on average 2.3 (EDTA) and 2.5 (LH) times higher Hp concentrations compared with serum, whereas no differences were seen with the ELISA results between sample types. Based on a clinical cut-off value, both methods differentiated sick from healthy cows. Haptoglobin measurements with the ELISA were less precise compared with CA measurements due to high dilutions. No influence of the anticoagulants on the CA was observed. Due to measurement discrepancies between serum and plasma, CAs for bovine Hp based on peroxidase activity should be performed with serum, or specific reference ranges for plasma samples should be established. In this study, CA results obtained with LH plasma were more precise than results obtained with EDTA plasma. Both the CA and the ELISA are suitable diagnostic tools for the diagnosis of puerperal metritis, but CA measurements were more precise in this study.

Development of a forensic DNA research grade test material.

Advancements in forensic DNA typing technology and methods have increased sensitivity and, while beneficial, carry the weight of more challenging profile interpretation. In response, the forensic DNA community has often requested more complex reference materials to address commonly encountered measurement and interpretation issues such as complex DNA mixtures, DNA degradation, and PCR inhibition. The National Institute of Standards and Technology (NIST) released Research Grade Test Material 10235: Forensic DNA Typing Resource Samples to support the forensic DNA community. Components include three single source samples, two degraded samples, and three mixture samples. As part of the Research Grade Test Material (RGTM) process, automated methods for bottling, alternative sample tube types, and the addition of carrier RNA for stabilizing low-quantity samples were investigated. Both internal and external testing demonstrate the stability of the material over time at 4°C through qPCR testing. In the development of a data portal, users have been allowed to anonymously upload results and compare their data with NIST and others. This report describes the preparation and stability of this material.

Differences Between Serum and Plasma: An Indirect Approach to Derive a Combined Reference Interval for Total Protein, Albumin, and Globulin

Abstract The objective of our study is to derive reference intervals (RI) for total protein (TP), albumin and globulin that are appropriate for both plasma and serum samples by applying statistical analyses to retrospective patient data. Both plasma and serum are acceptable matrices for these tests at our institution, with a single RI that applies to all specimens. The widespread shortage of lithium heparin (LH) tubes that occurred as a consequence of the pandemic prompted our lab to switch the primary tube type for comprehensive metabolic panels (CMPs) from LH to serum separator tubes (SST) in October 2021. The primary tube type reverted to LH in October 2023, and no adjustments were made to RIs at either time. To determine how well our RIs align with the accepted matrices, we used R Statistical Programing version 4.3.1 to apply an indirect, nonparametric statistical approach to data extracted from the laboratory information system (LIS) between July 2018 and December 2023. All orders for TP, albumin and globulin were queried to include the following components in the analysis: TP, albumin, globulin, serum TP, serum albumin and serum globulin. The records were divided into 3 epochs based on the primary tube type for CMP on the order date, with epochs 1 and 3 reflecting LH and epoch 2 reflecting SST. We attempted to identify a subset of serum and plasma samples in healthy individuals by applying exclusion criteria based on inpatient status, age, and draw station at which the specimen was collected. For each component, a resampling bootstrap method was used to calculate the RIs and corresponding 95% confidence intervals by epoch. Our results show that the RI of TP, albumin and globulin changed significantly between the epochs, reflecting the difference in primary matrix. The components serum TP, serum albumin, and serum globulin did not see a significant change in values over the epochs. A verification study looking at plasma and serum samples in 20 healthy individuals support these results. Based on these findings, our reference intervals were updated from 6.6-8.7 g/dL to 5.9-8.3 g/dL for TP, from 3.6-4.9 g/dL to 3.6-5.1 g/dL for albumin and from 2.3-3.5 g/dL to 1.5-3.9 g/dL for globulin. We show that there are statistically and potentially clinically significant differences in the reference intervals of TP, albumin and globulin in serum compared to plasma. This study demonstrates a big data analytics approach to derivation of RIs and emphasizes the importance of RI assessment and adjustment for patient population and acceptable specimen type.

Numerical study on fluid flow pattern regulation and heat transfer characteristics in oval-pit spiral tube

Spiral tube heat exchangers are widely applied in daily industrial production. In order to improve the comprehensive heat transfer performance of the spiral heat exchanger to meet industrial production and policy demands, improvements to spiral heat exchangers are necessary. In this study, a new type of oval-pit spiral tube is proposed. Ansys Fluent software was used to develop the numerical models and simulate the heat exchange conditions in smooth spiral tube and oval-pit spiral tube. The development and evolution of secondary flow and heat transfer characteristics in spiral tube were analyzed by theoretical analysis, and the heat transfer mechanism was explored. The dimensionless temperature parameter Θ and dimensionless acceleration number Ω were defined to explore the influence of secondary flow on heat transfer characteristics, which provided a new approach for improving spiral heat exchangers. The results show that the secondary flow in the smooth spiral tube has a symmetric double-vortex structure, and it has an asymmetric double-vortex structure in the oval-pit spiral tube. Compared with smooth spiral tube, the local dimensionless temperature parameter Θ in oval-pit spiral tube fluctuates more sharply, the heat transfer non-uniformity is greater, and the local Nu number is higher. Additionally, the fluid in the oval-pit tube is fully developed at the smaller axial angle, and the flow and heat transfer stability are better. In the working range of inlet Reynolds number of 1000∼5000, compared with smooth spiral tube, the heat transfer coefficient of oval-pit spiral tube increases by 11.58∼44.73 %, the pressure drop increases by 33.56∼119.27 %, and the comprehensive heat transfer performance increases by 1.23∼14.65 %.

Medical Alert Cards for Pediatric Patients With Antegrade Continence Enemas to Enhance Awareness

IntroductionThe antegrade continence enema (ACE) is a surgical technique that establishes a route for colonic irrigation, necessitating a detailed comprehension of the procedural methodology, including the conduit construction, the catheters selection, and the administration of irrigation solutions. It is critical to disseminate comprehensive information regarding ACE procedures to health-care professionals and caregivers to enhance their understanding and support management of patients undergoing this intervention. This study aims to evaluate the efficacy of a novel educational tool designed to augment the knowledge base of physicians and caregivers regarding ACE procedures. MethodsMedical alert cards were conceptualized for patients managed with ACEs via an appendicostomy, neoappendicostomy, or cecostomy. These cards included essential information such as (1) contact details of the health-care team, (2) specifics of the surgical procedure, (3) criteria for emergency department referral, and (4) bespoke patient-specific information. A single-institution survey was conducted to assess the cards’ role in improving awareness of ACE procedures among health-care providers and caregivers and guiding management of patients with ACEs. The study adhered to Consensus-Based Checklist for Reporting of Survey Studies guidelines. ResultsTwenty-seven responses were collected from 18 health-care providers and nine caregivers. A significant majority (n = 24, 88%) affirmed the cards’ effectiveness in providing detailed information about individual patients. The design and layout of the card were well-received by 93% (n = 25) of respondents, with a median readability score of 8 (interquartile range 7-10). Additionally, some providers (n = 3, 17%) highlighted the card’s utility in facilitating patient referrals to specialized care centers. Suggestions for improvement included adding information about different types of tubes, enhancing readability, and optimizing the visual representation of the conduit. ConclusionsMedical alert cards demonstrated a significant potential to improve understanding of ACEs among health-care providers and caregivers. The cards aid in informing stakeholders about the ACE procedure, guiding the child’s management, and referring the patients to specialized care facilities when necessary.

A-060 Assessing Glucose Stability: A Comparison of Citrate/NaF, NaF, and Gel Separator Vacuum Tubes in Routine Medical Laboratory Practice

Abstract Background In cases where a glycolysis inhibitor is not utilized, blood cells in vitro can consume glucose. Although current guidelines suggest using citrate-buffered inhibitors or ice-water slurry to mitigate this, practical and financial constraints often hinder adherence to these recommendations. Our objective was to evaluate the difference in glucose concentration in our routine sample management by employing Citrate buffered/NaF, NaF, and Gel Barrier tubes. Methods In this study, we utilized Greiner FCmix citrate-buffered NaF and EDTA tubes (3 mL), Becton Dickinson NaF and EDTA tubes (4 mL), and Becton Dickinson SSTII Gel Barrier tubes (5 mL). Following venipuncture, the tubes were transferred to the laboratory and centrifuged within 30 minutes. Glucose levels of 46 patients' samples were measured using a Cobas 6000 system (c501) employing the Glucose Hexokinase method, which exhibits an intermediate coefficient of variation (CV) of approximately 1.5% and no significant bias, as confirmed by monitoring with Biorad EQAS. Results The mean plasma glucose difference between Citrate-buffered tubes and NaF tube samples was 2.8 mg/dL with a 95% confidence interval (CI) ranging from 2.2 to 3.4 mg/dL (Mean: 0.16 mmol/L; CI: 0.12 - 0.19 mmol/L). The difference in paired samples of NaF plasma and Gel Barrier tubes serum glucose was 3.2 mg/dL with a CI of 2.5 - 3.9 mg/dL (Mean: 0.18 mmol/L; CI: 0.14 - 0.22 mmol/L). Lastly, the mean difference in Citrate-buffered plasma and serum Gel barrier tubes for 46 paired samples was 6.0 mg/dL with a CI of 5.2 - 6.7 mg/dL (Mean: 0.33 mmol/L; CI: 0.29 - 0.37 mmol/L). Conclusions Following guidelines, Citrate-buffered/NaF tubes demonstrate efficacy as glucose stabilizers. When compared to NaF tubes alone within a 30-minute timeframe, the mean difference between the two types of tubes was 2.8 mg/dL. Although NaF tubes are no longer recommended for glucose testing in plasma, they still outperform gel barrier serum tubes by 3.2 mg/dL. Furthermore, compared to citrate/NaF Plasma, serum glucose levels were on average 6.0 mg/dL lower. The preanalytical sample stage poses a significant obstacle to its reliable use for diagnostic or monitoring purposes. Laboratories should consider transitioning to Citrate/NaF tubes, or employ mathematical corrections if utilizing gel separator tubes for glucose testing in their established preanalytical process.

B-357 Siemens CA 72-4: an assay for measurement of Tumor Associated Glycoprotein (TAG) 72

Abstract Background The tumor associated glycoprotein (TAG) 72, also known as CA 72-4 is a mucin protein of high molecular weight. CA 72-4 is found on the surface of many cancer cells, including stomach (gastric), ovary, breast, colon and pancreatic cells. CA 72-4 is currently one of the primary markers for the diagnosis of gastric cancer and monitoring the course and efficacy of gastric cancer. In ovarian cancer, it has a higher sensitivity for mucin- type ovarian cancer, and its combination with CA125 for detection can significantly improve the clinical sensitivity. In colorectal cancer, CA 72-4 combined with CEA detection was also found to significantly improve the sensitivity of the initial diagnosis. An assay for CA 72-4 on Siemens Atellica IM (Siemens CA 72-4) is being developed and analytical performance is being presented. Methods The Siemens CA 72-4 assay (in development) is a one-step chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of CA 72-4 in human serum and plasma. The specimen is incubated with paramagnetic microparticles coated with the monoclonal antibody (mAb) B72.3 and acridinium-labeled mAb CC49 conjugate on the Siemens Atellica IM® System. After incubation and washing, Acid and Base reagents are added. The resulting relative light units (RLUs) are directly proportional to the amount of CA 72-4 in the sample allowing for the quantitative determination of CA 72-4 in the specimen. Results The following performance were determined using 3 unique lots of reagents and calibrators with the calibration range for the assay being 0.00 to 200.00 U/mL. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation at 20% CV (LoQ) were determined and met the goal of ≤ 1.00 U/mL. Linearity according to CLSI EP06 Ed2 was demonstrated for a range of 1.00 through 200.00 U/mL. A Precision study of 2 controls and 5 panels spanning the range of the assay demonstrated a total %CV ≤ 6% for samples ≥ 5.00 U/mL and ≤ 0.25 SD for samples &amp;lt;5.00 U/mL. In the sample tube type study, a matrix comparison of 23 matched serum and plasma samples were evaluated. Passing-Bablock slopes of &amp;lt; 8% and r &amp;gt; 0.99 were observed when evaluating samples within the measurement range for plasma (LiHep, LiHep separator, K2EDTA and K3EDTA) tubes and serum separator tubes (SST) compared to the Red Top serum samples. Five endogenous substances were evaluated for interference in the CA 72-4 assay. The average percent difference between test and control samples for all endogenous interferents was &amp;lt; 10%. Percent difference in the presence of 28 potentially interfering drugs was ≤ 4.0%. Conclusions The Siemens CA 72-4 assay currently in development is a sensitive and precise assay for the quantitative determination of CA 72-4 in human serum and plasma.

B-356 Siemens CYFRA 21-1: an assay for measurement of cytokeratin fragment 21-1

Abstract Background Cytokeratins are structural proteins forming the subunits of epithelial intermediary filaments. The soluble fragment of cytokeratin 19, cytokeratin fragment 21-1 (CYFRA 21-1), can be found in the blood of lung cancer patients, primarily those with non-small cell lung cancer (NSCLC). CYFRA 21-1 is the preferred biomarker in the management of NSCLC, particularly squamous cell and large cell carcinoma subtypes. An assay for CYFRA 21-1 on Siemens ADVIA Centaur® XPT and Siemens Atellica® IM (Siemens CYFRA) is being developed and analytical performance is being presented. Methods The Siemens CYFRA 21-1 assay (in development) is a one-step chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of CYFRA 21-1 in human serum and plasma. The specimen is incubated with paramagnetic microparticles coated with the monoclonal antibody (mAb) BM19.21 and acridinium-labeled mAb KS19.1 conjugate on the Siemens ADVIA Centaur XPT System and Siemens Atellica IM System. After incubation and washing, Acid and Base reagents are added. The resulting relative light units (RLUs) are directly proportional to the amount of CYFRA 21-1 in the sample allowing for the quantitative determination of CYFRA 21-1 in the specimen. Results The following performance were determined using 3 unique lots of reagents and calibrators with the calibration range for the assay being 0.00 to 100.00 ng/mL. For the ADVIA Centaur XPT and Atellica IM systems were shown to be equivalent within 4%. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation at 20% CV (LoQ) were determined and met the goal of ≤ 1.00 ng/mL. Linearity according to CLSI EP06 Ed2 was demonstrated for a range of 0.66 through 100.00 ng/mL. A Precision study of 2 controls and 5 panels spanning the range of the assay demonstrated a total %CV ≤ 8% at all levels. In the sample tube type study, a matrix comparison of 61 matched serum and plasma samples were evaluated. Passing-Bablock slopes of &amp;lt; 5% and r &amp;gt; 0.99 were observed when evaluating samples within the measurement range for plasma (LiHep, LiHep separator, K2EDTA and K3EDTA) tubes and serum separator tubes (SST) compared to the Red Top serum samples. Six endogenous substances were evaluated for interference in the CYFRA 21-1 assay. The average percent difference between test and control samples for all endogenous interferents was &amp;lt; 10%. Percent difference in the presence of 20 potentially interfering drugs was ≤ 4.0%. Conclusions The Siemens CYFRA 21-1 assay currently in development is a sensitive and precise assay for the quantitative determination of CYFRA 21-1 in human serum and plasma.

A-209 Preanalytical Phase Errors Constitute the Vast Majority of Errors in Clinical Laboratory Testing

Abstract Background Laboratory errors can occur during the preanalytical, analytic, or post-analytic phase of testing and may pose a considerable threat to patient safety. Studies have estimated that pre-analytical error encapsulates ∼45-68% of laboratory errors and occurs in up to 1.52% of specimens. However, limitations of previously published studies include the use of manual error detection, reliance on manual transcription, small study sizes, and exclusion of common errors. Herein, we aim to identify the types and frequency of errors occurring in each phase of clinical laboratory testing using a large retrospective dataset across a broad range of errors detected in clinical laboratories. Methods This study was performed in the Barnes-Jewish Hospital core laboratory which provides testing for a 1,400-bed tertiary care hospital and included all tests performed for clinical chemistry, special chemistry, toxicology, automated hematology, blood gas testing, coagulation, non-infectious serology, infectious disease serology, urinalysis, and send out testing between January 2022 and May 2023. Errors were compiled from two separate sources. The first source of errors was captured from the laboratory information system (LIS, Cerner). These errors were flagged manually by laboratory staff in real time. The second source of error was a daily report manually curated by a trained medial laboratory scientist as part of routine, laboratory operating procedures and standard workflow. Results There were ∼40,000,000 individual results from ∼11,000,000 specimens during the study period and 87,317 errors observed (∼0.8% of specimens). Of these errors, specimens that were hemolyzed sufficiently to impact result but still reportable were the majority (41,047, 47.2%). When excluding minimal hemolysis, there were 46,270 errors documented. Among these, 44,847 (97.0%) were in the preanalytical phase, 451 (1.0%) were in the analytical phase, and 972 (2.0%) occurred in the postanalytical phase. Subcategorization of preanalytical errors revealed that most of the errors were related to hemolyzed samples requiring results to be suppressed (n=19,701), quantity not sufficient samples (n=8,068), clotted specimens (n=5,840), collection errors (e.g., wrong tube type, n=5,780), not on ice (n=1,369) and IV fluid contamination (n=1,122). In the analytical phase, the causes of error were interfering substances (n=279), QC out of range (n=65), instrument problems (n=58) and reagent issues (n=49). Among the postanalytical errors, 581 were comment errors, 216 were results entry errors, 131 were comments errors with potential impact on patient care, and 44 were dilution errors. Conclusions This study demonstrates that the vast majority of lab errors (∼97.0%) occurring during the preanalytical phase. The high incidence of preanalytical errors, especially errors related to sample integrity implies a need for enhanced tools and training to minimizing errors from specimen collections, maintenance of sample stability, transportation, and processing.

Main heat transport system configuration influence on steam drum level control and safety for a pressure tube type boiling water reactor with multiple interconnected loops

Abstract NCABWR (Natural-Circulation-Advanced-Boiling-Water-Reactor) is a pressure-tube-type BWR with multiple inter-connected Main-Heat-Transport (MHT) system loops and steam drums (SDs). SD-Level-Control is related to, the MHT coolant inventory and sustained heat removal, hence the overall safety of the Nuclear-Power-Plant (NPP). SD-Level is vital for ensuring presence of adequate coolant-inventory with sufficient and prolonged cooling of fuel, for normal-operation and accidents. In the initial-MHT-configuration of NCABWR the four MHT-loops are, inter-connected at the Common-Reactor-Inlet-Header (CRIH), which influences the SDLC adversely; such occurrences are, not reported in the open literature. Open loop (without SD-level-controllers) step-change response showed that initial MHT-configuration response is stable, non-oscillatory and non-diverging even for a high-magnitude step-change in the feed-flows. Closed-loop (with SD-level-controllers) response, even to minor disturbances leads to diverging SD-Levels due to CRIH-MHT-configuration (Gaikwad, A.J., Vijayan, P., Iyer, K., Bhartiya, S., Kumar, R., Lele, H.G., Ghosh, A.K., Kushwaha, H.S., and Sinha, R.K. (2009). Effect of loop configuration on steam drum level control for a multiple drum interconnected loops pressure tube type boiling water reactor. IEEE Trans. Nucl. Sci. 56: 3712–3725). CRIH is required to overcome Postulated-Initiating-Event (PIE) for single-accumulator-failure-LOCA. A hypothetical MHT-configuration with partitioning of CRIH will isolate each loop from one another and lead to a stable SDLC, but then for the above-mentioned PIE safety is not met. LOCA in one of the four ECCS header-compartments require a mandatory interconnection among, the four MHT-Loops at CRIH. Solution to SDLC issue were explored with changes in MHT-configuration and with innovative solution-schemes for feed-water-system and SDLCs. In the present study the pioneering solution-schemes with individual SD pressure control for SD level control and the Split/Double baffle are proposed, implemented and the performance was tested with simulation are discussed in details with other solution schemes.

Effect of Fine-Pore Aeration Tube Layout on Dissolved Oxygen Distribution and Aeration Performance in Large-Scale Pond

Dissolved oxygen (DO) is a crucial water quality characteristic in the cultivation of vannamei shrimp. Increasing the DO concentration in shrimp ponds can be carried out using the aeration method with a tool called an aerator. In this study, types of fine-pore aeration tubes are chosen. This aerator offers multiple benefits, such as superior aeration efficiency, effortless installation, and minimal clogging. In practice, fine-pore aeration tubes can be arranged according to needs, so the layout used can influence the resulting aeration performance. This research uses the computational fluid dynamics (CFD) method to analyze DO distribution, water circulation, and aeration performance (KLa20, SOTR, and SOTE) produced in various aerator layouts, namely straight-type, ring-type, and square-type, in a vannamei shrimp pond. The results show that the straight-type layout has the best DO distribution because it is spread throughout the pond area. The square-type layout has the best water circulation because it has the largest area with water velocities of less than 5 cm/s. The optimal aeration performance was achieved with the straight-type layout, which demonstrated a KLa20 value of 3.16 h−1, SOTR value of 19.20 kg/h, and SOTE of 29.30%.

Optimizing Diagnosis and Management of Ventilator-Associated Pneumonia: A Systematic Evaluation of Biofilm Detection Methods and Bacterial Colonization on Endotracheal Tubes

Healthcare-associated infections, such as ventilator-associated pneumonia and biofilm formation on intubation cannulas, impose significant burdens on hospitals, affecting staffing, finances, and patient wellbeing, while also increasing the risk of patient mortality. We propose a research study aimed at exploring various methodologies for detecting these infections, discovered in the biofilm on medical devices, particularly tracheal cannulas, and understanding the role of each method in comprehending these infections from an etiological perspective. Our investigation also involves an analysis of the types of endotracheal tubes utilized in each case, the bacteria species identified, and strategies for combating biofilm-associated infections. The potential impact of our research is the substantial improvement of patient care through enhanced diagnosis and management of these infections.

Numerical simulation study of boiling heat transfer of R290 flow in horizontal microtubes

Abstract R290 is considered to be an excellent alternative refrigerant for domestic air conditioners in the future. In this paper, CFD numerical simulation was used to obtain the flow field distribution of R290 in a micro-fine circular tube with an inner diameter of 2mm under a specific range of working conditions, and the effects of saturation temperature, mass flow density, heat flow density and tube type on the boiling heat transfer characteristics of R290 tube were investigated. The results show that the boiling heat transfer coefficient increases with the increase of saturation temperature, and the maximum value of the heat transfer coefficient increases by 8.1% when the saturation temperature increases from 284K to 286K. The boiling heat transfer coefficient increases with the increase of mass flow density, and the maximum value appears in the medium dryness range. The boiling heat transfer coefficient in the tube increases and then decreases when the heat flow density increases from 10 kW/m2 to 20 kW/m2 and increases faster at high heat flow density conditions. In addition, compared with the circular tube, the boiling heat transfer coefficient in the elliptical tube with an aspect ratio of 1.56 increases by 2.78% for R290 under the same flow area.

Experimental study on the influence factors of falling film heat transfer characteristics outside different types of horizontal tubes

An experimental setup was established to analyze the performance of a spiral wound heat exchanger applied to natural gas liquefaction. The boiling behavior of subcooled flow over a small diameter, non-round, horizontal tube was investigated using n-pentane as the working fluid. The effects of flow rate, heat flux, fluid inlet temperature and tube spacing on heat transfer performance were investigated. Based on the experimental conditions of this study, the results indicate that: (1) raising the Reynolds number can effectively enhance the heat transfer coefficient; (2) the increasing in heat flux also has a positive impact on heat transfer performance, but the extent of which is related to the Reynolds number; (3) increasing the tube spacing resulted in higher heat transfer coefficients; (4) under the same working conditions, the heat transfer performance of non-round tubes is higher than that of round tubes; (5) correlation equations were developed to calculate the Nu for smooth, round, elliptical, and egg-shaped tubes. The predictions made by these correlation equations deviated by less than 10 % from the experimental results for the entirety of the experimental conditions.

Improvement in heat transfer and flow pattern of sprayed falling on horizontal tubes with rib structure for a sewage source heat pump

The falling film flow and heat transfer characteristics are critical to improve the performance of spray heat exchangers in a sewage source heat pump (SSHP), which is influenced by the operating and structural parameters. Therefore, considering the unique flow patterns of wastewater falling film caused by the oily content, and the influence of heat exchange tubes with surface structures on flow and heat transfer, two types of heat exchanger tubes with axial and circumferential ribs were designed and the falling flow over tubes were investigated through CFD method using VOF model. The falling film flow pattern, liquid film coverage and heat transfer coefficient (HTC) outside the ribbed heat exchange tubes were investigated, and the influence of rib structures and Re were analyzed. It was found that oily wastewater liquid film spreaded differently depending on the rib structures, and circumferential ribs of case 2 improved the flow pattern by increasing film coverage, which obviously affected the tube HTC. At higher Re, the ribbed tubes displayed higher potential in better heat transfer performance. Therein, the circumferential ribbed tubes showed highest average HTC, with up to 31.9 % higher than smooth tubes, which can be further enhanced by increasing Re. This study provides a foundation for enhancing the heat transfer performance of spray heat exchangers in sewage source heat pumps through the design and modification of tube surface structures.

Radial compression performance of glass fiber reinforced polyurethane composite tube with open-hole

Glass fiber reinforced polyurethane matrix composite (GFRP) is a novel composite material. GFRP circular tubes are widely used in engineering because of its excellent mechanical properties. It is inevitable to open holes on GFRP circular tubes when connecting with other components due to the use requirements and structural needs. The radial compression test, theoretical analysis, and finite element calculation of GFRP circular tubes produced by the braiding-winding-pultrusion process are carried out, to study the influence of holes on the compression performance of tubes. The GFRP circular tube has four layers with different fiber angles. From the inner to the outer structure layer, they are the inner woven layer, winding layer, longitudinal fiber layer, and outer woven layer. The mechanical properties of a 0° unidirectional plate are better than those of a 90° unidirectional plate according to the mechanical properties test. The radial compression tests are carried out on GFRP circular tubes with a length of 300 mm, an outer diameter of 140 mm, and a wall thickness of 6 mm. The theoretical calculation of the bearing capacity of the GFRP circular tube under the radial compression load in the elastic stage and the failure stage is well matched with the bearing capacity obtained from the test. The theoretical calculation can effectively predict the bearing capacity of the GFRP circular tube. The radial compression test of GFRP tubes is simulated by ABAQUS, which is a finite element software. The good agreement between the finite element calculation results and the test results verifies the feasibility of the finite element. Based on the above research, finite element models are established for different types of GFRP circular tubes to study the influence of opening ratio on the load borne by GFRP circular tubes. The results show that the hole with the opening rate less than or equal to 1/10 has little effect on the load of the GFRP circular tube. This paper studies the influence of opening on the radial compression properties of GFRP tubes, which has certain reference value for the opening of composite tubes in engineering.

Crashworthiness design for novel polygonal asymmetric origami tubes

Origami tubes have attracted widespread attention because it is inclined to deform in the complete diamond mode (DM) with a low initial peak force Fmax and high average crushing force Fave. Although conventional origami tubes can improve crashworthiness, there are still many areas that fail to generate traveling plastic hinge lines, and the crashworthiness can be further improved. This paper presents a novel polygonal asymmetric origami tube (PAT) with origami patterns that can trigger more traveling plastic hinge lines compared to those of conventional origami patterns. The theoretical analysis of the deformation mechanism suggests that the PAT can realize hierarchical deformation and avoid stress concentration at sharp corners. The quasi-static experiments and numerical simulations reveal that the novel origami pattern can successfully trigger up to four times more traveling plastic hinge lines than the conventional square box (CSB) under the premise that each plastic hinge line is similar in length. Compared with the CSB, the PAT can deform in DM with a 56.0 % reduction of Fmax and a 59.1 % increase of Fave. Notably, the stableness of load-carrying capacity SLC is 90.2 %, which is 260.8 % higher than the CSB. A series of parametric studies reveal that the dihedral angle ratio α / β and the width-to-thickness ratio c / t of the PAT have a significant effect on crashworthiness. A smaller ratio of α / β and c / t provides the PAT with superior crashworthiness. Comparing the PAT with other types of origami tubes and multi-cell tubes indicates that the PAT also exhibits outstanding crashworthiness. The impact experiments also unveil a significantly enhanced crashworthiness of the PAT. Compared with the CSB, the Fmax decreases by approximately 46.4 %, while the Fave increases by around 92.7 %. The SLC and SEA values for the PAT surpass those of the CSB by about 260.8 % and 93.1 %, respectively. Furthermore, the theoretical analysis for predicting the Fave of the PAT is developed, with a maximum error not exceeding 8.5 %.