The non-axisymmetric three-dimensional flow and heat transfer in the stagnation-point region of a planar jet impingement boiling on a flat surface has been investigated by using similarity solution ...approach, considering additional diffusivity terms in momentum and energy equations as a result of bubble-induced mixing in flow. The free jet stream along
z
direction impinges on the surface and produces a flow with different velocity components. This situation may happen if the flow pattern on the plate is bounded from both sides in one of the directions, because of any physical limitation or due to conditions of the surface such as moving plates or stretching sheets with different values of stretching velocities in the
x
and
y
directions. The governing equations have been transformed into ordinary differential equations by introducing appropriate similarity variables, and an exact solution has been obtained for three-dimensional boiling problem for the first time. The similarity variables have been presented based on non-axisymmetric three-dimensional and additional diffusivity effects. The bubble-induced diffusion due to bubble formation, growth, departure and collapse causes an enhancement in heat transfer rate from the surface to the bulk flow. The total heat flux transferred from the surface to the flow has been estimated as summation of the single-phase heat transfer due to forced convection and the nucleate boiling heat flux due to bubble-induced diffusion. The effects of the velocity components ratio and the ratio between the maximum total diffusivity to the molecular diffusivity on the flow field and heat transfer characteristics have been obtained and discussed and illustrated graphically. A comparison of the predicted heat flux has been made with previously published experimental data. As expected, the average deviation values show relatively more accurate results for the three-dimensional simulation than the two-dimensional one because of being closer to the experimental conditions.
Background The associated factors and patterns of giving birth in home settings of rural areas have been extensively studied in Bangladeshi literature. However, urban areas still need to be explored, ...particularly with recent data. Therefore, the authors aimed to investigate the influential determinants of delivery at home in urban areas of Bangladesh. Materials and methods In this study, 1699 urban-dwelling women who had given birth within the previous 60 months of the survey and lived in urban areas were used. The secondary data were extracted from the latest Bangladesh Demographic and Health Survey 2017-2018. Descriptive statistics and logistic regression were applied along with the association among selected variables were examined by the Chi-square test. Results Findings depict that 36.49% of women who lived in urban areas of Bangladesh delivered at home, whereas, 63.51% delivered at different govt. and private health care facilities. Women who lived in Chittagong adjusted odds ratio (AOR) = 2.11, 95% CI 1.24-3.60, Barisal AOR = 2.05, 95% CI 1.16-3.64 and Sylhet AOR = 1.92, 95% CI 1.08-3.43 divisions have more likelihood to deliver at home (36.85%). Urban women following Christian religion AOR = 10.71, 95% CI 1.32-86.68 have higher odds of delivering child at home (0.47%). Urban women having three or more children before her latest delivery (22.37%) and who are employed (29.37%) have more likelihood to deliver at home. However, women aged between 25 and 34 years (43.50%), who have higher education (25.90%), play the role of household head (9.06%), have parity of more than two births (2.24%), and read daily newspapers (68.69%) had a lower chance of delivery at home. Furthermore, women from wealthier families (89.12%) and more antenatal care (ANC) visits (94.93%) were less likely to have a delivery at home. Conclusion Despite significant progress in women and reproductive health in Bangladesh, the proportion of delivery in the home in urban areas is alarming and should be emphasized more. The authors believe the identified factors will help design interventions and policy development on this issue. Keywords: Determinants, Delivery at home, Reproductive health, Bangladesh
To ensure reliable operation of electrical systems, batteries require robust battery monitoring systems (BMSs). A BMS’s main task is to accurately estimate a battery’s available power, referred to as ...the state of charge (SOC). Unfortunately, the SOC cannot be measured directly due to its structure, and so must be estimated using indirect measurements. In addition, the methods used to estimate SOC are highly dependent on the battery’s available capacity, known as the state of health (SOH), which degrades as the battery is used, resulting in a complex problem. In this paper, a novel adaptive battery health estimation method is proposed. The proposed method uses a dual-filter architecture in conjunction with the interacting multiple model (IMM) algorithm. The dual filter strategy allows for the model’s parameters to be updated while the IMM allows access to different degradation rates. The well-known Kalman filter (KF) and relatively new sliding innovation filter (SIF) are implemented to estimate the battery’s SOC. The resulting methods are referred to as the dual-KF-IMM and dual-SIF-IMM, respectively. As demonstrated in this paper, both algorithms show accurate estimation of the SOC and SOH of a lithium-ion battery under different cycling conditions. The results of the proposed strategies will be of interest for the safe and reliable operation of electrical systems, with particular focus on electric vehicles.
Type-2 fuzzy logic controllers (T2 FLC) can be viewed as an emerging class of intelligent controllers because of their abilities in handling uncertainties; in many cases, they have been shown to ...outperform their Type-1 counterparts. This paper presents a literature review on recent applications of T2 FLCs. To follow the developments in this field, we first review general T2 FLCs and the most well-known interval T2 FLS algorithms that have been used for control design. Certain applications of these controllers include robotic control, bandwidth control, industrial systems control, electrical control and aircraft control. The most promising applications are found in the robotics and automotive areas, where T2 FLCs have been demonstrated and proven to perform better than traditional controllers. With the development of enhanced algorithms, along with the advancement in both hardware and software, we shall witness increasing applications of these frontier controllers.
Natural convection heat transfer inside concentric annular enclosures has been well researched for decades. Such enclosures have been employed as intermediate layers between fluid streams in heat ...exchangers, particularly in latent heat thermal energy storage applications. Convection heat transfer coefficients originating from natural convection are relatively low, which drives the need for heat transfer enhancements by using extended surfaces (e.g., fins, heat sinks). In this study, numerical simulations are performed to investigate the natural convection heat transfer inside a concentric annulus in the presence of Y-shaped fins. Each Y-shaped fin has four important geometric parameters: (i) length of the fin base a, (ii) length of the fin branches b (i.e., the V-section), (iii) primary fin spacing angle θ, and (iv) secondary fin angle or branch angle α. Steady-state simulations are conducted using COMSOL Multiphysics® with constant temperature boundary conditions to generate the laminar natural convection profiles in the enclosure filled with air. The average Nusselt numbers, calculated at both the inner and outer walls of the enclosure, are used to gauge the heat transfer. The model is built with thin layer approximated fins first and subsequently compared to a modified model with fins with finite thickness. The optimized case using the thick fin model is found to yield a percent increase in Nu of 358.8% compared to the case with no fins. Lastly, the entropy generation is considered to determine the second law efficiency of the system, which is approximately 91%.
•Natural convection in horizontal concentric annulus with Y-shaped internal fins.•Fin geometric parameters are swept to explore effects on Nu.•Thin layer fin approximation is compared to “thick” fins for selected cases.•Optimal Y-shaped fin arrangement yields 358.8% increase to Nu compared to no fins.•Thin layer approximation loses accuracy as fin thickness is increased.
In the Wnt canonical pathway, Wnt3A has been known to stabilize β-catenin. In the non-canonical Wnt signaling pathway, Wnt is known to activate Rho GTPases. The correlation between canonical and ...non-canonical pathways by Wnt signaling, however, has not been well elucidated. Here, we identified that Wnt3A promoted superoxide generation, leading to Tyr42 phosphorylation of RhoA through activations of c-Src and Rho-dependent coiled coil kinase 2 (ROCK2) and phosphorylation of p47phox, a component of NADPH oxidase. Wnt3A also induced accumulation of β-catenin along with activations of RhoA and ROCK1. Concurrently, ROCK1 was able to phosphorylate GSK-3β at Ser9, which phosphorylated Src at Ser51 and Ser492 residues, leading to Src inactivation through dephosphorylation of Tyr416 during the late period of Wnt3A treatment. Meanwhile, p-Tyr42 RhoA bound to β-catenin via the N-terminal domain of β-catenin, thereby leading to the nuclear translocation of p-Tyr42 RhoA/β-catenin complex. Notably, p-Tyr42 RhoA as well as β-catenin was associated with the promoter of Vim, leading to increased expression of vimentin. In addition, stomach cancer patients harboring higher expressed p-Tyr42 Rho levels revealed the much poorer survival probability. Therefore, we propose that p-Tyr42 RhoA is crucial for transcriptional regulation of specific target genes in the nucleus by binding to their promoters and involved in tumorigenesis.
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•ROCK2 phosphorylates p47phox, a component of NADPH oxidase, leading to superoxide production upon Wnt3A.•Wnt3A upregulates not only β-catenin but also p-Tyr42 RhoA through Src, which is activated by superoxide.•p-Tyr42 RhoA/β-catenin complex translocates to nucleus and binds to the promoter of Vim, leading to vimentin expression.•ROCK1 phosphorylates GSK-3β at Ser9, resulting in Ser493 and Ser51 phosphorylation of Src and its inactivation for desensitizing Wnt3A.•Cancer patients harboring high p-Tyr42 RhoA level reveal the much poorer survival probability.
One of the main solutions to the issue of global warming and greenhouse gas emission caused by burning fossil fuels is storing energy in an efficient way. In this work, the detailed melting process ...of RT-35 as a phase change material (PCM) inside a cylindrical latent heat thermal energy storage (TES) system is investigated both numerically and experimentally. To achieve this aim, an experimental setup comprising of a transparent vertical cylindrical enclosure as a latent heat TES system, a constant temperature bath, and a temperature regulator is built. Moreover, a numerical model using COMSOL multiphysics is developed to simulate the melting process and provide a more detailed information on the flow and thermal fields. The model is able to provide the temperature and velocity fields, heat transfer behaviour, melting fraction, and the trend of solid-liquid interface at different time intervals. To validate the numerical model, a comparison between melting fraction and solid-liquid interfaces of the numerical model and experimental work is conducted which shows a good agreement between experimental and numerical results.
The advent of innovative engineering concepts and technologies to improve traditional systems for refrigeration, storage, and transportation of foods is inevitable to reduce energy consumption and ...thus reduce greenhouse gas emissions from the food sector. In this study, a Phase Change Material (PCM) based Thermoelectric (TE) refrigerator has been presented. As a novelty, the proposed prototype is evaluated experimentally with different tests by using the wind tunnel and temperature controller. The results indicate that the PCM-based TE refrigerator can maintain the temperature of a variety of food products for applications such as refrigerator vehicles. The suggested system can keep materials at temperatures below 5 ºC for 7 h without electricity. Based on the findings, by using PCM, the proposed refrigerator can maintain the temperature of the food items below 5 ºC without electricity for 29.4% of one week's hours facilitating the system for applications with unstable access to electricity. Furthermore, the life cycle environmental impacts (including global warming potential and ozone depletion) of the PCM-based TE refrigerator have been determined and compared with conventional refrigerators. The global warming potential, ozone depletion, smog, acidification, and eutrophication of the proposed refrigerator are found to be, 1190 kg of CO2 e, 1.29E-06 kg of CFC-11, 58.5 kg of O3, 15.8 kg of SO2, and 0.242 kg of nitrogen, respectively, which is about 28% lower than the magnetic refrigerator's CFC-11 emissions. Consequently, the results conclusively demonstrate that transitioning to a PCM-based TE refrigeration system significantly reduces the environmental impacts of the food transportation and storage sector.
Background and Aims
Due to the availability of more sophisticated cell phones with top‐notch gaming functions, the present generation is more active. The available literature indicates that ...adolescents experience a variety of psychological issues, like low self‐control brought on by an addiction to mobile games. Because of this, the aim of this study is to control the prevalence of, and factors that contribute to, online gaming addiction and its effects on academic performance in Bangladeshi university students.
Methods
Convenient sampling was adopted to collect primary data from 399 Bangladeshi university students utilizing a prestructured questionnaire. Descriptive statistics, the χ2 test, binary logistic regression, and multinomial logistic regression were also used to accomplish the study's objective.
Results
According to this study, 62.7% of students play online games over 30 h every week. The findings also show that male students are more inclined than female students to show signs of addiction. Also, regular online gaming can result in long‐term problems, and that factor including age, internet access, educational background, and frequency of play can influence the likelihood of these problems. The findings shows that a lower cumulative grade point average (CGPA), less physical activity, and less study time are associated with playing online games for at least 30 h per week. Moreover, the study found that playing online games, playing for long time, and skipping class can all have an adverse effect on a student's academic performance.
Conclusions
The authors recommend that the authorities set up a good entertainment environment and take into account the findings of this article to discourage students from playing online games. Furthermore, encouragement of extracurricular activities such as sports or other pursuits is also essential in assisting Bangladeshi students in overcoming their addiction to mobile games.
Experimental investigations on the technical viability of solid oxide fuel cells to replace internal combustion engines in automobiles have increased in recent years. However, the performance and ...stability of catalysts in the presence of carbon is key for the commercial success of fuel cell reformers. In this paper, finite element method was used to study the effect of coke deposition on heat and mass transfer during the catalytic partial oxidation of ethanol in a packed bed reactor. The properties of Ni/Al2O3 catalyst bed were investigated after being subjected to several hours of carbon buildup. Bed permeability, porosity, and temperature distribution were significantly affected after just 1500 s of reaction time. It was observed that void fraction and permeability became nonuniform across the bed. These two parameters decreased with axial position, and the difference became more pronounced with time. A decrease in bed porosity reduced the bed temperature due to an increase in effective thermal conductivity and ethanol conversion and hydrogen selectivity decreased as a result. Thus, it was concluded that heat transfer becomes a limiting factor in reforming reactions in the presence of carbon. Production distribution before deactivation was also studied, and it was observed that a maximum ethanol conversion of 100% was achieved at 600 °C and a C/O ratio of 1.0. Finally, results from the reactions were compared to that of a different study to validate the reaction mechanism and similar results were found in the literature.
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