Lee Model Research Articles

Improved age estimation from semen using sperm-specific age-related CpG markers

Accurate age estimation from semen has the potential to greatly narrow the pool of unidentified suspects in sexual assault investigations. However, previous efforts utilizing semen age-related CpG (AR-CpG) markers have shown lower accuracy compared to blood AR-CpG-based methods. This discrepancy may be attributed to DNA methylation (DNAm) interferences from “round cells” such as leukocytes and immature sperm cells in semen. This study aimed to develop age calculators based on sperm-specific AR-CpG markers and to achieve performance-improved age estimates from sperm DNA. Through an analysis of publicly available MethylationEPIC microarray data from 90 sperm samples of healthy males aged 22–51 years, we identified 31 sperm-specific AR-CpG markers with absolute Pearson’s R values > 0.5 and Benjamini-Hochberg adjusted p values < 0.013. The top 19 AR-CpG markers with the largest absolute R values and beta ranges > 0.10, along with 3 reported semen AR-CpG markers (cg06304190, cg06979108, and cg12837463), were integrated into two methylation SNaPshot panels (Ⅰ and Ⅱ), each containing 11 markers. The 21 qualified AR-CpG markers showed absolute R values ≥ 0.427 in an independent validation cohort of 253 sperm DNA samples (22–67 years), with cg21843517 exhibiting the strongest age correlation (R = 0.853). The optimal models, constructed using sperm DNAm data of the training set (n = 214, 22–67 years) and markers from panel Ⅰ (n = 11), panel Ⅱ (n = 10), or both panels, achieved mean absolute errors (MAEs) of 2.526–4.746, 3.890–5.715, and > 9.800 years on the test sets of sperm (n = 39, 23–64 years), semen (same donors as the sperm test set), and whole blood (n = 40, 22–65 years), respectively. The simplified models incorporating 3, 5, 9, or 14 AR-CpG markers (MAE = 2.918–4.139 years for sperm) still outperformed the Lee et al. original model (MAE = 6.444 years for semen) and the reconstructed panel Lee model (MAE = 6.011 years for sperm). The final models, utilizing all sperm DNAm data (n = 253) and markers from panel Ⅰ, panel Ⅱ, or both panels, yielded mean MAEs of 2.587, 2.766, and 2.200 years, respectively, on the 50 test sets generated by 5 repeats of 10-fold cross-validations. Additionally, multiple markers in both panels demonstrated the ability to discern sperm or semen from blood with 100% accuracy. In summary, our study substantiates the potential of sperm-specific AR-CpG markers for precise age estimation from sperm DNA, providing an improved toolset for forensic investigations.

Fluid–Thermal–Structural Analysis of Partial Admission Axial Impulse Turbines With Liquid Jet Impingement Cooling

Abstract Increasing turbine inlet temperature is beneficial to enhance turbine performance. However, this also results in stringent cooling requirements. Unlike turbines in air cycle machines, the partial admission axial impulse turbines for underwater vehicles can utilize the abundant seawater as the cooling medium. In addition, the short blades cannot accommodate the complex cooling channels used in aero-engines, and the alternative way is jet impingement liquid cooling. This paper proposes a fluid–thermal–structural coupling method to investigate the performance of partial admission axial impulse turbines with water-cooling on the rotating wheel front surface. The volume of fluid multiphase model is employed to study the transient gas–liquid interaction, while the Lee model is chosen to model the heat and mass transfer during phase change. Also, a two-way weakly coupling method among fluid, thermal, and structure is utilized to account for fluid–structure interaction. The results show that the temperature distribution at the turbine wheel drops significantly with the jet impingement liquid cooling. The turbine efficiency is also reduced by 3.38% due to the mixing of cooling medium and gas. From stress analysis, the use of water-cooling can minimize turbine damage and ensure stable turbine operation. This study provides insight into the cooling method for partial admission axial impulse turbines for the underwater vehicle.

Role of Vacancies in the Yao–Lee Model

Role of Vacancies in the Yao–Lee Model

A modified dynamic Lee model for two-phase closed thermosyphon (TPCT) simulation

A modified model consisting of a dynamic Lee model, volume of fluid model, and continuum surface force model is developed. The modified model investigates heat transfer characteristics of the vapor–liquid phase change process and details of the two-phase flow during operation of a two-phase closed thermosyphon. The mass transfer time relaxation parameters for the Lee phase change model are the most critical coefficients which determine the rate of the vapor–liquid phase change. A dynamic adjustment of the mass transfer time relaxation parameters for the Lee phase change model is realized based on the amount of mass transfer between the vapor and liquid phases and the values of the mass transfer time relaxation parameters become stabilized. The relative error between the modified model and experimental data for the temperature distribution is 5%, representing an acceptable agreement. Compared with the original model, the maximum thermal resistance errors in evaporation section and condensation section are reduced by 19.3% and 107.1%, respectively. These results indicate that the modified model can provide good corrections with high accuracy.

3D numerical investigation on flow boiling characteristics in large length-to-diameter ratio microchannel

To meet the demand of thermal management with large power and high heat flux in the future engineering applications, more and more attentions have been draw to develop the two-phase microchannel cooling technology. In this work, a three dimensional numerical investigation is performed to study the influence of mass flux and heat flux on the two phase flow boiling characteristics in a single microchannel with large length-to-diameter ratio. The related calculation results show that the Volume of Fluid (VOF) model coupled with Lee model can predict the two phase pressure drop and heat transfer coefficient of the microchannel well. And the flow patterns in the microchannel are classified as bubbly flow, slug flow and annular flow, which can be captured by this numerical model precisely. Besides, the transient pressure drop augments with the increase of mass flux. But the effect of mass flux on the amplitude of quasi-steady pressure drop and the peak value of time-averaged heat transfer coefficient along the microchannel is small. At last, the amplitude of quasi-steady pressure drop increases with the augmentation of heat flux. The maximum and fully developed time-averaged heat transfer coefficients along the microchannel increase with the heat flux.

Experimental and computational investigation of thermal performance and fluid flow in two-phase closed thermosyphon

Over the last two decades, energy recovery has become increasingly important in the transition from fossil fuels to green energy. Waste heat recovery, such as the two-phase closed thermosyphon (TPCT) type of heat exchanger, is a highly efficient energy recovery technique. However, accurately predicting the thermal performance and flow patterns in TPCTs is challenging due to the complex physics of phase-change phenomena. A new predictive model is suggested that can provide improved accuracy when predicting thermal performance and flow patterns in TPCTs. An experimental study was conducted to acquire the data, and the results were compared with computational results obtained from the new proposed model. The model uses the volume of fluid (VOF) model with the Lee model for the phase change process in OpenFOAM v2106. To increase accuracy, the saturation temperature and vapor density were defined as a function based on the mass balance in the TPCT. In addition, a simulation was conducted to predict the thermal performance and flow patterns in a TPCT, during which the effects of the empirical value of the mass transfer intensity factor were investigated. The study is expected to provide insights into phase-change modeling with high accuracy and an understanding of the thermal characteristics of TPCTs.

A numerical analysis study on the characteristics of evaporation in liquid hydrogen tank with vacuum layer according to changes in heat flux and vacuum pressure

Recently, many studies have been conducted on hydrogen, one of the new energy sources, because of environmental pollution and energy depletion. In the case of liquid hydrogen, since it is necessary to maximize insulation performance to maintain a cryogenic (20 K) environment, high-pressure gas hydrogen is currently applied that simply increases pressure and increases density. However, liquid hydrogen compared to gas hydrogen has the advantage of compressing the volume by 800 times and compared to high-pressure hydrogen gas (70.0 MPa high-pressure hydrogen gas), it can secure a density of about 10 times, which is advantageous in terms of storage/transportation. Therefore, in order to convert its form from high-pressure hydrogen to liquid hydrogen in the transport and storage of hydrogen energy, study on storage tanks with insulation performance that can maintain liquid hydrogen is needed. This work presents a numerical simulation study on characteristics of evaporation in liquid hydrogen tank related to heat flux and vacuum pressure by using verified numerical method. To study this characteristics of evaporation in liquid hydrogen tank, first, data of a prior study with numerical analysis data was compared to verify the numerical method. In this step, the coefficient values for the evaporation model was presented. Second, the heat conduction value according to the degree of vacuum was calculated by using rarefied gas condition and set on the outer wall of the liquid hydrogen tank to confirm the insulation performance according to the increase in the degree of vacuum. As a result, the mass transfer time relaxation parameter of the Lee model applied for evaporation simulation was derived as about 0.0035 1/s by trial and error. In addition, as a result of research from the perspective of thermal conductivity according to the pressure reduction of the vacuum layer, it was confirmed that the vacuum degree should be maintained below 0.001 to 0.0001 torr and the insulation performance effect was insignificant due to the decrease in vacuum layer pressure.

New empirical flow-regime-based model of water boiling in rectangular microchannels

A new empirical flow-regime-based model of water boiling in rectangular microchannels is proposed and programmed using MATLAB code in the present paper. The prediction model divides the flow regime map into four parts: single-phase convection regime, sub-cooled boiling regime, saturated boiling regime, and partial dry-out boiling regime. Each zone is also divided into several sub-zones according to corresponding criteria. Suitable empirical heat transfer correlations and flow transition criteria are adopted for each flow pattern to reasonably capture the boiling heat transfer mode according to the vapor quality or the efficient heat flux. The prediction results generally present a similar trend to experimental results from the literature. The new model is also compared with the existing empirical flow-regime-based models in the literature. The Lee and Mudawar model and the Ma model can only capture up to 3 and 2 different trends of HTC, respectively. However, the new model considers a complete flow regime map and can capture up to 4 different trends of HTC.

LES model of flash-boiling and pressure recovery phenomena during release from large-scale pressurised liquid hydrogen storage tank

The paper presents large eddy simulations (LES) model of two-phase (liquid-gas) hydrogen behaviour during pressurised tank venting. The results of simulations are compared against published experiment on flash-boiling of liquid hydrogen (LH2) in a large-scale tank of 7.622 m height, 2.3 m internal diameter, filled with LH2 to 6.248 m (80% tank filling) at pressure 321.8 kPa gauge. The volume-of-fluid model is applied for tracking phases and Lee's model is used to simulate evaporation and condensation. The effect of various Lee's model evaporation-condensation coefficients on the process dynamics is assessed. The simulations are compared against experimental pressure dynamics monitored at the venting pipe and experimental temperature measured by thermocouples in gaseous and liquid phases during the first 15 s of venting. The LES model reasonably predicts physical phenomena during depressurisation of LH2 storage tank, including the pressure recovery phenomenon, LH2 level and temperature dynamics in the tank.

The effectiveness of AR e-module of flower structure material on biology students’ science literacy

The electronic-module (e-module) is one of the teaching materials needed so that the learning process can take place optimally. E-module owned by UM biology students generally do not use the latest technology. Augmented Reality (AR) is a form of technology where there is a process of integrating the virtual world with the real world. Not a few students experience difficulties in understanding the flower structure material. Student scientific literacy is still far from what is expected. The research conducted is Research and Development with the Lee and Owens Development Model. Data collection was carried out during October-December 2022. The technique of analyzing quantitative descriptive data. The subjects in this study were 37 biology students class of 2021 without any differences in gender, age and study program. The results of the effectiveness of the AR electronic-module based on n-gain calculations obtained a score of 0.7 where on that score the AR e-module was categorized as quite effective in increasing scientific literacy. It is hoped that in the future there will be teaching materials and media that can improve some of the competencies needed by the latest generation.

Excess mortality associated with the COVID-19 pandemic during the 2020 and 2021 waves in Antananarivo, Madagascar

IntroductionCOVID-19-associated mortality remains difficult to estimate in sub-Saharan Africa because of the lack of comprehensive systems of death registration. Based on death registers referring to the capital city of Madagascar,...

Numerical study on the interfacial heat and mass transfer characteristics of bubble direct contact condensation with the effect of non-condensable gas

Bubble condensation is one of the fundamental issues in the direct contact condensation, which is also affected significantly by the existence of non-condensable gas. In this study, a further investigation is carried out on air-steam bubble condensation with the Proportion Integration Differentiation (PID) control model which adjusts the mass transfer coefficient of Lee model in each time step by comparing the parameters obtained in the simulation with the ones calculated based on the empirical correlations originated from the experiments. Furthermore, species transport equations are employed to obtain the local mass fractions of steam and air. The proposed simulation schema is verified by the existing experimental data.Results show that the air-steam bubble condensation can be divided into initial and stable stages. The mass transfer coefficient used in Lee model can be regarded as linear growth over time at each stage, but with different slopes. The non-condensable gas can weaken the heat and mass transfer of condensation, but stabilize the bubble deformation. The present study also reveals the influences of subcooling and initial bubble diameter on the air-steam bubble condensation, which is expected to be instructive for better understanding the effect of non-condensable gas on the interfacial characteristics of bubble condensation in subcooled water.

High-order parametrization of the hypergeometric-Meijer approximants

In this work, we introduce an extension to the hypergeometric algorithm we developed before for the resummation of divergent series. The extension overcome the time-consuming problem we face in the parametrization process of the hypergeometric approximants. In the previous version, the parametrization process results in a set of non-linear equations which is hard to solve (might be impossible) for relatively high orders (greater than six) using normal PCs with Mathematica software for instance. To solve this problem, we formulate an equivalent (order by order) linear set of equations which is easy to solve in an appropriate time using normal PCs. We also show that such extension of the hypergeometric resummation algorithm is able to employ non-perturbative information like strong-coupling and large-order asymptotic data which are always used to accelerate the convergence. We applied the algorithm for different orders (up to O(29)) of the ground state energy of the x4 anharmonic oscillator with and without the non-perturbative information. We also considered the available 20 orders for the ground state energy of the PT−symmetric ix3 anharmonic oscillator as well as the given 20 orders of its strong-coupling expansion or equivalently the Yang–Lee model. For high order weak-coupling parametrization, accurate results have been obtained for the ground state energy and the non-perturbative parameters describing strong-coupling and large-order asymptotic behaviors. The employment of the non-perturbative data accelerated the convergence very clearly. The High temperature expansion for the susceptibility within the SQ lattice has been also considered and led to accurate prediction for the critical exponent and critical temperature.

Development and modified implementation of Lee model for condensation simulation

Numerical oscillation is a non-physical phenomenon in which the interface temperature fluctuates around the saturation temperature. The simulation for condensation is more susceptible to the numerical oscillation caused by the phase change model. To suppress the numerical oscillation and reduce interface temperature deviation in condensation simulation, a developed model modified the Lee model is presented in this study. In the present model, the mass source terms and the energy source terms are added in the governing equations to calculate the condensate within the cell and the allocation of condensation energy between the interface cells. The mass and energy source transfer model is firstly compared with the original Lee model to simulate one-dimensional Stefan problem. Indicating that with the similar accuracy the developed model could increase computational efficiency by 40 times. Then the Nusselt condensation problem is verified with a reasonable selection of model parameters, and the average error of the film thickness was controlled below 2%, as the interfacial temperature deviation within 3%. Finally, verification is also attained on the forced convective condensation of R134a and the interfacial temperature deviation is below 0.1 K. Simulation results validate the feasibility of using this model to predict heat and mass transfer in condensation. The numerical oscillations are also significantly suppressed in the simulations.

Improvement on evaporation-condensation prediction of Lee model via a temperature deviation based dynamic correction on evaporation coefficient

Lee model has been commonly accepted for modelling the mass transfer processes subject to both evaporation or condensation. However, severe concern caused by improper setting of mass transfer relaxation coefficient exists for the high-accuracy prediction. The complicated influence factor and variable parameters result in the failure of definition on the mass transfer relaxation coefficient. In this paper, the temperature deviation based dynamic modification model to define the evaporation mass transfer relaxation coefficient (MTRC) is proposed. The MTRC is no longer needed to be manually adjusted and numerous human and computation resources could be saved, with better prediction accuracy. The hyperbolic tangent function is applied to describe the relationship between the evaporation MTRC and the product of temperature deviation and volume fraction. Compared with the commonly used Lee model, better prediction accuracy at the evaporation section can be achieved with the prediction error lowered by 38.79%, 16.24% and 4.38% under power input of 100.65, 49.61 and 19.88 W, and the maximum relative error decrement by 44.74% and the average reduction by 14.26%, which could be attributed to the elimination of liquid temperature deviation. Note that the liquid temperature deviations are strictly restrained within acceptable range 0–2 K all the time with the dynamic correction model while the temperature deviation by common Lee model would up to 13 K. Meanwhile, the proposed model is found to effectively save the computational time with reduction around 83.3% because of the quick match of the mass transfer rate impacted by the modified evaporation coefficient.

Experiments and modelling of liquid nitrogen jet release and dispersion for fire-related applications

Cryogenic liquid nitrogen (LN2) is proposed as an effective fire suppressant/extinguisher for challenging fires. Upon reaching a fire source, this inert cryogen vaporizes expediently and separates the fuel from the air. Additionally, it cools the burning fuel and slows down its pyrolysis/gasification reactions. A prior investigation concentrated on the survivability of single LN2 droplets, following breakup of the jet exiting the nozzle, and the predicted the droplet size that reaches a target. This investigation addresses the application of a liquid nitrogen jet for the extinction of fires with a combination of experiments and theoretical analysis. Small scale laboratory experiments were conducted with a sprayer and larger scale experiments were conducted with a cryogenic hose and nozzle. In these experiments the reach of the liquid nitrogen jets was measured, and their fire extinction capabilities were assessed. Numerical simulations were performed with the ADREA-HF CFD code using the mixture approach and explicit modelling of LN2 evaporation using the Lee model. Numerical results on the reach of a liquid nitrogen jet qualitatively matched the experimental observations for release of a liquid nitrogen jet in open atmosphere. The Lee model coefficient was found to depend strongly on the nozzle diameter. An integral model was also constructed to explore the effects of relevant parameters, such as the LN2 storage tank pressure, the initial jet vapor quality, the jet velocity at the nozzle exit and the effects of the ambient air entrainment. Based on experiments and theoretical analysis, it became evident that for effective extinction of a fire with liquid nitrogen a commercial nozzle should have a large diameter and should be brought close to the burning target, i.e., within a few meters. As this action can pose potential safety risks to firefighters, the advancement of the nozzle towards the fire should be operated remotely.

Research on Bruce Lee's Classic Film Image and Cross-cultural Communication

Bruce Lee was a well-known actor, martial artist, and philosopher who brought quality films to people. At the same time, he used his way to spread Chinese culture to the world. This kind of cross-cultural communication was undoubtedly very successful at that time. This paper introduces the influence of Bruce Lee, the symbol of the era on the cross-cultural communication mode and the combination of films through the literature summary. Bruce Lee's model of cross-cultural communication was based on the medium of film. Due to the popularity of the Internet and social media, the effect of movies on cultural communication is gradually diminishing. The achievements made by internet celebrities headed by Li Ziqi on social media are gradually forming a new and significant cross-cultural communication effect. Cross-cultural communication is based on media consistent with social development and use its characteristics to maximize the benefits of cross-cultural communication.

Observation of plasma dynamics in a theta pinch by a novel method

A novel experimental method is proposed for observing plasma dynamics subjected to magnetic fields based on a newly developed cylindrical theta-pinch device. By measuring simultaneously the temporal profiles of multiple parameters including the drive current, luminosity, plasma density, and plasma temperature, it provides a basis for observing the plasma dynamics of the theta pinch, such as shock transport and magnetohydrodynamic instability. We show that the plasma evolution can be distinguished as three phases. First, in the radial implosion phase, the trajectories of the current sheath and shock wave are ascertained by combining experimental data with a snowplow model (Lee model) in a self-consistent way. Second, in the axial flow phase, we demonstrate that m = 0 (sausage) instability associated with the plasma axial flow suppresses the plasma end-loss. Third, in the newly observed anomalous heating phase, the lower-hybrid-drift instability may develop near the current sheath, which induces anomalous resistivity and enhanced plasma heating. The present experimental data and novel method offer better understanding of plasma dynamics in the presence of magnetic fields, thereby providing important support for relevant research in magneto-inertial fusion.

Evaluation of several liquid–vapor phase change models for numerical simulation of subcooled flow boiling

The phase change model has recently attracted attention for use in flow-boiling numerical simulation research. Comparison and evaluation of the calculation accuracies and resource consumptions of phase change models are essential for developing an efficient and high-precision phase change model. In this study, the Dong and Chen models, were added to the FLUENT software as two new models by introducing a unique user-defined function (UDF). The two unique models and the Lee model served as the foundation for numerical research, and the values of dependabilities and properties for flow and heat transmission predicted by these models were compared. Visual studies and flow-boiling heat transfer correlations were used to validate the results. The results reveal that the Chen model, which considers the active nucleation density site of bubbles, has a significant advantage over the other two models in terms of predicting flow characteristics. The Lee and Dong models are better suited for forecasting the changing tendency of the heat transfer coefficient, whereas the values obtained with the Chen model are closer to the reference values for the Liu–Winterton correlation. Besides, the two novel models also have higher computational costs.

Development of Online Web Learning with Ethnomatematics Content on Self Regulated Learning

Along with the development of technology, a set of abilities is needed to master the 21st-century skills which are often referred to as 4C, namely Critical Thinking, Communication, Collaboration, and Creativity and Innovation. The purpose of this research is to develop online web learning with ethnomathematics content on self-regulated learning. The development model in this research is to develop online web learning with ethnomathematics content on KPK and FPB material for elementary schools with the Lee and Owen model design (2004). The development model consists of (1) analysis, (2) design, (3) development, (4) implementation, and (5) evaluation. After discussing the findings, this study produces several conclusions. First, in order to achieve learning outcomes and learning objectives, content from the etomathematics aspect is needed in the KPK and FPB materials so that students do not only get mathematics but understand how elements of local culture can foster a love for local culture. Second, to foster student interest, it requires the use of images, audio and video more than text. Third, applications can be used to support learning. This is due to the limited time that the researcher has. In the future, products that have been made large group trials and tests on student self-regulated learning.