Twin Flow Research Articles

Research and application of intelligent diagnosis method for impeller fault based on centrifugal pump digital twin flow field cloud map

With the development of industrial technology, the demand for health diagnosis and maintenance of centrifugal pumps is becoming increasingly urgent. Combining digital twin and machine vision technology, this paper proposes an intelligent diagnosis method for centrifugal pump impeller machinery fault based on digital twin flow field cloud map. Firstly, the centrifugal pump digital twin model is used to simulate the evolution of random fracture fault of impeller blades, and the impeller flow field pressure and velocity cloud maps with different fault characteristics are generated; secondly, based on the learning and training of Yolov5 algorithm, two types of machine vision models of pressure and velocity cloud maps are obtained, and the preliminary diagnosis of impeller faults is realized by combining statistical analysis; then, considering the complementary advantages of the two types of detection models, the two are integrated based on the idea of stacking integration to improve the accuracy of impeller fault diagnosis. Experimental verification shows that for random fracture faults of impeller blades, the centrifugal spring intelligent fault diagnosis method proposed in this paper can achieve a diagnostic accuracy of more than 0.99, and the developed intelligent diagnosis system for centrifugal pump impeller machinery faults enables the method in this paper to be put into practice.

Information Flow in Digital Twin for “Detection to Repair” of Defects Using Additive Manufacturing

Digitalization in inspection and manufacturing results in a wide range of advantages including the reduction of cost, complexity, and operation time, and increasing the flexibility, level of automation, and the capabilities to gain intelligence. This paper discusses an attractive benefit of digitalization which allows the integration of the information flow and control for the two processes of digital inspection and additive manufacturing. A digital twin of the additive manufacturing process is dynamically updated based on the intermittent inspection data obtained from the workpiece to integrate the information of the digital model for planning and controlling additive manufacturing process. The ultimate objective is to repair highly expensive, and large components in industrial sectors. The developed digital twin for this integrated system includes eight activities are demonstrated through an industrial case study.

(Invited) Redox Flow Battery Research, Development, and Manufacturing

Redox flow batteries are increasingly recognized as a promising candidate for large-scale grid energy storage due to their unique architecture that decouples the power and energy. This feature is desirable for long-duration energy storage since it enables the flow batteries to singularly increase the duration without the concomitant cost increase of the power component. This presentation will give an overview of the current research and development of the redox flow battery technologies, especially considering their manufacturing challenges from material synthesis, electrolyte formulation, cell components, and devices to the systems. Focuses will be given to developing organic redox-active molecules, new testing technics, testing protocols, and procedures. A data-driven flow battery research, development, and deployment platform, a digital twin flow battery, will also be discussed.

Doppler Waveform Analysis of Intertwin Venous Blood Flow in Twin Reversed Arterial Perfusion (TRAP) Sequence with a Rudimentary Heart.

Twin reversed arterial perfusion (TRAP) sequence is a rare anomaly in 1% of monochorionic twin pregnancies. Few TRAP sequence cases have a rudimentary heart with cardiac motion in the acardiac twins. Herein, we investigated the venous Doppler waveform in two cases of TRAP sequence with a rudimentary heart with cardiac motion in the acardiac twin. Although both cases had veno-venous anastomoses, the venous Doppler waveforms of the umbilical vein differed. A comparison of the characteristics of the cases indicated that the existence of a ductus venosus, or greater heart pulse power, in the acardiac twin might impact the venous Doppler waveform in the pump twin.

Monitoring colorless electroactive chemicals in complex background based on electrochemical difference absorption spectroscopy with twin flow cells

Conventional UV/Vis absorption spectroscopy is an economical and user-friendly technique for online monitoring, however, by which some electroactive chemicals are hardly determined in the presence of fluctuating background due to the formation of colored chemicals. Here, we propose an electrochemical difference absorption spectroscopy (EDAS) to accurately quantify colorless chemicals based on visible color change via electrolysis with strong variation in the background. EDAS is realized by twin spectroelectrochemical flow cells system, replacing the two cuvette cells of a dual beam spectrophotometer. Each cell consists of a three-electrode system, quartz windows and a thin flow channel. Flowing of analyte from one cell (reference cell) to the other (sample cell) can eliminate the influence of colored interferents even while their concentrations are changing. When different potentials are applied on the sample and reference cells respectively, electrolysis occurs and colored products flowing through quartz windows can absorb the incident light, resulting in difference absorption spectra induced from potential difference. We find that steady-state difference absorbance (ΔA) at characteristic wavelength is linearly changed with sample concentrations. EDAS is firstly verified by Fe(CN)64− at different potentials and flow rates, in good agreements with a simplified theory that describes linear relationship between ΔA and analyte concentration. Then EDAS is used to determine Cu(I) in Cu(I)–Cu(II) mixed solutions and tetramethylbenzidine in its partially oxidized solutions to illustrate the powerful ability to detect colorless chemicals with varied background, implying its promising potential applications in the chemical industry.

Towards Organizational Development In Digital Organizational Twin

Sustained continuous monitoring and replication of organizational development in digital organizational twins is of particular importance for labour-intensive enterprises and also those in which reciprocal relations between social, corporate, normative and performative aspects assume the leading role. The main purpose of the research is the developing of a digital representation of organizational processes, which focuses on the performance, working activities, organizational issues, behaviour and interactions between of the organizational members. Consequently, the objectives of research include the monitoring of current research state, concept and design of a digital twin. The implementation of digital organizational twin should improve considering timely optimization of proactive and reactive organizational development measures in the company in relation to the core variables of the 7S model. The created digital twin should map the dynamics of organizational development, as well as concomitant and deviating processes. Systematization literary sources and approaches for the digital replication of organizational development issues indicates the lack of publications on research and diffuse distribution of scientific interest. The initial design of organizational development in the digital twin is based on four main objects and limited to a certain number of investigated parameters. This paper compare the conventional and digitalized organizational development process, explain the data flow in digital organizational twin, the design of organizational development in the digital organizational twin, provide an overview of the individual facets of organizational development, list the parameterization models and exemplarily illustrate the visualization of selected parameters. The results of the research can be useful for the expansion of the tension bridge between organisational development and technologies and the development of new potentials for the study of socio-technical effects in companies. This can be extended to include the other facets of business management and supplemented by the connection of other technological resources.

Outcome of Pregnancies Diagnosed with TRAP Sequence Prenatally: A Single-Centre Experience

Introduction: Twin reversed arterial perfusion (TRAP) sequence is a phenomenon seen in 1–3% of monochorionic twin pregnancies, where the acardiac fetus is found to have multiple anomalies. The normal pump twin maintains its own perfusion in addition to that of its acardiac co-twin. As a result, if the acardiac twin increases in size, the burden on the pump twin is increased, leading to cardiac failure, hydrops fetalis, polyhydramnios, premature delivery, and perinatal death. The outcome of pregnancy is largely dependent on the growth of the acardiac twin. In view of high perinatal loss, surgical techniques to interrupt the blood flow to the acardiac twin have been evaluated. Methods: We evaluated interstitial laser therapy, which is the main mode of therapy in our unit, of TRAP pregnancies referred over a 5-year period. Interstitial laser was offered if the blood flow in the acardiac twin was found to be persistent at 2 consecutive examinations or if there were cardiac or hydropic changes in the pump twin at the first examination. Results: A total of 18 cases of TRAP were referred during this period and all were counselled regarding fetal therapy if the situation were to deteriorate; 5 couples (27.7%) opted for termination of pregnancy; of the remaining 13, 7 (53.8%) agreed to perform intervention following confirmation of a normal karyotype. Six (85.7%) and 1 (14.3%) lasers were performed in the second and third trimesters, respectively; all 7 had a normal outcome of the pump twin. There were 6/13 (46.2%) in the expectant group who continued the pregnancy with no intervention, with 2 term live births (33.3%). Conclusions: Our study confirms that there is a high risk of spontaneous loss in untreated pregnancies with TRAP, primarily due to polyhydramnios and fetal hydrops. In the pregnancies that underwent interstitial laser, there was a more favourable outcome. Interstitial laser is minimally invasive, safe, and feasible in experienced hands.

OC18.03: The relationship between recipient twin's hemodynamic deterioration and ductus venosus Doppler flow in Twin–twin transfusion syndrome

OC18.03: The relationship between recipient twin's hemodynamic deterioration and ductus venosus Doppler flow in Twin–twin transfusion syndrome

Design and Application of a Multidisciplinary Predesign Process for Novel Engine Concepts

The purpose of this paper is to present a multidisciplinary predesign process and its application to three aero-engine models. First, a twin spool mixed flow turbofan engine model is created for validation purposes. The second and third engine models investigated comprise future engine concepts: a counter rotating open rotor (CROR) and an ultrahigh bypass turbofan. The turbofan used for validation is based on publicly available reference data from manufacturing and emission certification. At first, the identified interfaces and constraints of the entire predesign process are presented. An important factor of complexity in this highly iterative procedure is the intricate data flow, as well as the extensive amount of data transferred between all involved disciplines and among different fidelity levels applied within the design phases. To cope with the inherent complexity, data modeling techniques have been applied to explicitly determine required data structures of those complex systems. The resulting data model characterizing the components of a gas turbine and their relationships in the design process is presented in detail. Based on the data model, the entire engine predesign process is presented. Starting with the definition of a flight mission scenario and resulting top level engine requirements, thermodynamic engine performance models are developed. By means of these thermodynamic models, a detailed engine component predesign is conducted. The aerodynamic and structural design of the engine components are executed using a stepwise increase in level of detail and are continuously evaluated in context of the overall engine system.

Intrafetal Laser Coagulation for Trap Sequence in a Complicated Dichorionic Triamniotic Triplet Pregnancy Case Report and Review of the Literature

Summary A rare case is reported of twin-reversed arterial perfusion (TRAP) sequence in a triplet pregnancy, fetal intervention in the first trimester and pregnancy outcome. We report a case of TRAP sequence complication in dichorionic triamniotic triplet pregnancy, with a normally developing fetus and an acardiac fetus connected via arterio-arterial anastomoses in a monochorionic diamniotic twin pair and a separate fetus. TRAP sequence was diagnosed at 13 weeks in triplet pregnancy after in vitro fertilization (IVF) and embryo transfer of two blastocysts. Color Doppler assessment showed persistent arterial flow in the acardiac twin. Intrafetal laser coagulation was carried out at the time of the diagnosis, and the pregnancy outcome was two survivals at 36.4 weeks of gestation.

Abnormal umbilical artery Doppler findings in the recipient twin before laser surgery for twin-twin transfusion syndrome.

In twin-twin transfusion syndrome (TTTS), persistent absent or reversed end-diastolic flow in the umbilical artery is a rare finding in the recipient twin, and the clinical implications of this finding are not well characterized. We sought to study the clinical importance of abnormal umbilical artery Doppler waveforms in recipient twins and determine the perinatal survival of these twins after laser surgery. A retrospective study of patients with TTTS treated with laser surgery between 2006 and 2012 was conducted. Recipient twins with absent or reversed umbilical artery end-diastolic flow on preoperative sonography were identified, and clinical and perinatal outcomes were compared to the remaining cohort. Statistical analyses were performed with Fisher exact and χ(2) tests. Of 369 consecutive TTTS cases, 14 (3.8%) had absent or reversed umbilical artery end-diastolic flow in the recipient twin. The rate of hydrops was higher in this group compared to those without absent or reversed flow (35.7% [5 of 14] versus 10.1% [36 of 355]; P = .0125). The rate of recipient twin growth restriction was also higher in the absent or reversed flow group (28.6% [4 of 14] versus 3.9% [14 of 355]; P = .0029). There was an increased rate of recipient fetal demise within 24 hours after surgery in those with absent or reversed flow (21.4% [3 of 14] versus 2.5% [9 of 355]; P = .0078), although there was no statistical difference in 30-day survival between the groups (78.6% [11 of 14] versus 89.9% [319 of 355]; P = .1751). Doppler findings of absent or reversed umbilical artery end-diastolic flow are rare in recipient twins. Although immediate post-laser surgery survival is relatively decreased in this group, overall perinatal survival rates appear to be favorable.

Doppler assessment of fetal aortic isthmus flow in twin.

ObjectiveThe purpose of this study was to investigate the aortic isthmus (AoI) flow difference between larger fetus and smaller fetus of twin; and to evaluate the predictive value of early diagnosis of hemodynamic change in twin growth.MethodsThis prospective study on 49 pairs of twin fetuses was performed to obtain AoI blood flow data. Cases with structural or chromosomal abnormalities and co-twin death were excluded. The interval from examination to delivery was within 4 weeks and 3 cases over 4 weeks interval were re-examined. Assessment of fetal AoI Doppler parameters were peak systolic velocity (PSV), end-diastolic velocity, times-averaged maximum velocities, pulsatility index (PI), and resistance index (RI). According to the direction of the diastolic flow in the AoI, antegrade and retrograde flow were made and was used to analyze the perinatal outcomes of each fetus. The predictive value of AoI Doppler parameters in predicting fetal growth was obtained by using ANOVA and logistic regression analysis of quantitative variables in each fetus of twins.ResultsThere were significant differences in the gestational weeks at delivery, birth weight and the incidence of growth discordance over 20% or more between monochorionic twin and dichorionic twin. The AoI PI and RI were significantly higher in smaller fetus than in larger regardless of chorionicity. Retrograde flow was noted in 8 of 98 cases (8.2%) and the only one case was of the larger fetus and the others were smaller fetuses of twin. Significant correlations were found between the AoI PI and birthweight (P=0.018) and between the PSV and growth discordance (P=0.032). In monochorionic twin, linear correlation was shown between the AoI PI and birthweight (P=0.004) and between AoI PI and growth discordance (P=0.031). Also, the meaningful correlation between the PSV and birthweight (P=0.036) was found by using logistic regression analyses.ConclusionOn the basis of our observation, AoI PI has revealed their hemodynamic status and this result may improve the understanding of growth patterns in twins.

Pressure dependence of excess enthalpy for (benzene + cyclohexane) mixture near the critical locus at T = (558.2, 563.2 and 573.2) K and p = (3 to 15) MPa

The pressure dependences of excess molar enthalpies HmE of the (benzene+cyclohexane) mixture at constant temperatures and compositions were measured near the critical locus, using a twin flow type mixing calorimeter. The measurement states are as follows; temperature T=(558.2, 563.2, and 573.2)K, mole fraction of benzene x=(0.119 to 0.916), and pressure range p=(3 to 15)MPa. The composition dependences of HmE at constant pressures and at each temperature were calculated from the pressure dependences of HmE. All pressure dependences of HmE have two peaks except at x=0.916. The pressure dependences at x=0.916 have one peak, and the curve at T=573.2K has a shoulder near p=5MPa. From the detailed consideration with respect to the phase behaviour near the critical locus for this mixture, two peaks should exist in the pressure dependences of HmE at T=558.2K and x=0.916, but the second peak cannot be detected because the peak width is too narrow. The composition dependences of HmE near the critical locus were skewed or S-shaped ones, which are ascribed as the characteristic behaviour in the vicinity of the critical locus.

Excess enthalpy for the (benzene + cyclohexane) mixture over a wide range of temperature and pressure

A twin flow type of mixing calorimeter was constructed for measuring excess enthalpies of fluid mixtures over wide temperature and pressure ranges. The precision of the calorimeter was tested with (water+ethanol) mixture. The excess molar enthalpies HmE for the (water+ethanol) mixture at temperatures T=(423.2 and 523.2)K and pressure p=5.00MPa and at T=523.2K and p=15.00MPa are in good agreement with the literature values. The HmE values for the (benzene+cyclohexane) mixture were measured using this calorimeter over the temperature range from T=298.2K to T=573.2K and the pressure range from p=5.00MPa to p=25.00MPa. All HmE values are positive and all mole fraction dependencies of HmE are almost symmetrically parabolic. The maximum values of the mole fraction dependence of HmE decrease with increasing temperature and are independent of the pressure, except for the conditions at T=(498.2 and 523.2)K and p=5.00MPa whose states are near the critical point of benzene. The maximum values of HmE of these states were greater than the values expected from the curve representing the temperature dependence of other maximum values of the mole fraction dependence of HmE.

Optimal Method and Timing of Intrauterine Intervention in Twin Reversed Arterial Perfusion Sequence: Case Study and Meta-Analysis

Introduction: The objective of this study was to define the optimal method and timing of intervention in twin reversed arterial perfusion (TRAP) sequence. Material and Methods: During a period of 20 years (1993-2013), we performed endoscopic laser coagulation of umbilical cord vessels or intrafetal laser in 67 pregnancies with TRAP sequence. These data were combined with those reported in the literature to determine the survival rate of the pump twin for different methods and timing of interventions. Results: A variety of techniques were used to interrupt the blood supply to the acardiac twin. Most procedures were performed at or after 16 weeks, and with most methods the survival rate of the pump twin was about 80%. Good results were also obtained for triplet pregnancies. In 18 of 30 cases (60%) diagnosed at 11-14 weeks, there was spontaneous cessation of flow in the acardiac twin before planned intervention at 16-18 weeks, and in 11 of these (61.1%) the pump twin died or suffered brain damage. In 103 pregnancies treated by intrafetal laser at 12-27 weeks, there was no correlation between gestational age at treatment and survival rate, but there was an inverse association between gestational age at treatment and gestational age at birth. Discussion: In TRAP sequence, survival may be improved by elective intervention at 12-14 weeks.

Successful pregnancy in triplet with trap sequence

A case report is presented on twin reversal arterial perfusion in Triplet. The acardiac twin usually grows along with the pump twin, but due to inadequate perfusion it is unable to develop the structures necessary for life. In this condition zero intervention will be associated with almost 100% mortality rate of one or all fetuses. Hence in utero therapy was decided for our patient. In utero thermogeneic coil was applied on the blood vessel to Acardiac monster. As there was reanastomosis, again second coil was applied. Subsequently, the blood supply to Acardiac was totally cut off. The pregnancy was scanned weekly thereafter and both fetuses maintained good growth without any evidence of cardiac decompensation in the pump twin. The acardius remained stable in size. As patient developed hydrominios, Amnioreduction was done further to prevent preterm labour. Expectant management and dexamethasone courses weregiven. At 35 weeks of gestation and ultrasound revealed redistribution of arterial blood flow in the pump twin. In view of the risk of further haemodynamic instability of the pump twin, a Caesarean section was done and delivered two alive babies weighing 2.4 kg and 2.6 Kg along with mumpified acardiac fetus.Since blood supply to acardiac twin was interrupted by 19 weeks our goal to get other two babies alive were achieved. This is the first case reported from Government R.S.R.M. Lying-in Hospital, Chennai, India.

Application of Twin Shear Unified Elastoplastic Finite Difference Method in Metallic Structures

Twin shear unified strength theory is applied to the numerical simulation of metallic structures with the method of elastoplastic finite difference.This work has actual significance for the problem of metallic structures strength or processing research.Firstly,the twin shear unified strength theory and the method of Lagrangian finite difference are briefly introduced.Secondly,the finite difference formulation of twin shear failure criteria and flow rule is derived and the model is loaded into FLAC code with dynamic-link library file compiled by language of C++.Finally,the cases of thick-walled cylinder under internal pressure and perforated plate in tension are calculated.The calculation results of analyses suggest that the precision of Lagrangian finite difference method and finite element method are similar.Twin shear unified strength theory can be applied to the metallic materials with a ratio of shear strength to tension strength between 0.5 and 0.667,so that it will have wide application in numerical simulation of metallic structures.

Selective intrauterine growth restriction in monochorionic twins: pathophysiology, diagnostic approach and management dilemmas

Selective intrauterine growth restriction (sIUGR) in monochorionic twins is associated with a substantial increase in perinatal mortality and morbidity for both twins. Clinical evolution depends on the combination of the effects of placental insufficiency in the IUGR twin with inter-twin blood transfer through placental anastomoses. Classification of sIUGR into types according to the characteristics of umbilical artery diastolic flow in the IUGR twin permits the differentiation of clinical and prognostic groups. sIUGR type I has normal diastolic flow and relatively good outcome. Type II is defined by persistently absent/reverse end-diastolic flow and is associated with a high risk of intrauterine demise of the IUGR twin and/or very preterm delivery. Type III is defined by the presence of intermittent absent/reverse end-diastolic flow (iAREDF), and is associated with 10-20% risk of unexpected fetal demise of the smaller twin and 10-20% risk of neurological injury in the larger twin. The management strategy for sIUGR with abnormal umbilical artery Doppler (types II and III) remains a challenge, and may include elective fetal therapy or close surveillance with fetal therapy or elective delivery in the presence of severe fetal deterioration. Small clinical series reporting the use of cord occlusion or laser therapy in severe cases suggest that the outcome of the larger twin might be improved. There is probably no single optimal strategy, since decisions will ultimately be influenced by the severity of IUGR, gestational age, parents' wishes and technical issues.

Umbilical venous volume flow in twin–twin transfusion syndrome

To examine umbilical venous volume flow (UVF) dynamics by twin status and disease severity in untreated twin-twin transfusion syndrome (TTTS). In 70 cases of untreated TTTS, absolute UVF, UVF corrected for estimated fetal weight (UVF/kg), intertwin difference (DeltaUVF/kg) and recipient to donor ratio (R/D-UVF/kg) were calculated. Parameters for UVF were compared with respect to twin status and disease severity (early, Quintero Stages I and II; advanced, Stages III and IV). UVF/kg was higher in recipients than in donors and decreased with advancing stage in both twins (in recipients, 183.9 mL/kg/min vs. 145.6 mL/kg/min, P = 0.043; in donors, 137.5 mL/kg/min vs. 122.5 mL/kg/min, P = 0.033). Linear regression analysis demonstrated that the overall best correlation coefficient for DeltaUVF/kg was obtained for the Doppler pulsatility index of the umbilical artery (t = - 4.536, P < 0.001). In advanced stage, absolute and weight-corrected UVF were lower overall, while significant differences in intertwin volume flows persisted. The lowest flows were observed in hydropic recipients (median, 67.0 (range, 55.2-122.0) mL/kg/min vs. 180.8 (range, 59.1-565.4) mL/kg/min; P = 0.001). In TTTS, UVF is significantly higher in recipients than in donors. With progression to advanced stage UVF/kg decreases in both twins as the magnitude of UVF that can be accommodated by the recipient declines. Further study of these dynamics in combination with cardiac performance parameters is warranted to refine diagnostic and prognostic assessment.

Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.