Transfer Situation Research Articles

Knowledge Transfer Quality Model Implementation - An Empirical Study in Product Engineering Contexts

Employee turnover, especially of experienced employees, is a constant challenge for companies as they are confronted with a loss of knowledge which they must compensate for. This leads to an accepted need to successfully transfer knowledge. Knowledge transfer has been reviewed in literature by multiple disciplines, whereas this paper focuses on a product engineering context. In this context, empirical research results show that knowledge transfer situations, e.g., communication of complex product specifications, can be improved regarding the speed of knowledge transfers by so-called interventions. Based on those findings, the quality of knowledge transfers is investigated further. Velocity-dependent, as well as quality-dependent interventions, are summarized in an intervention catalog. Whereas the effect of those velocity-dependent interventions has been investigated in empirical studies, the quality-dependent interventions have not yet been implemented in an industrial setting. This paper, therefore, describes the design and results of a workshop with experts from the area of knowledge management as well as from product development of universities and companies. The workshop was used to validate previously developed interventions and further add quality-dependent interventions. Further, the implementation of selected interventions in a product engineering context, using a Live-Lab as a research environment, is presented. The interventions intend to improve the quality of knowledge transfers in specific knowledge transfer situations. As this is validated by an empirical implementation study, the validity of this approach is justified.

A comparative numerical study of a semi-infinite heat conductor subject to double strip heating under non-Fourier models

The present work considers a two-dimensional (2D) heat conduction problem in the semi-infinite domain based on the classical Fourier model and other non-Fourier models, e.g., the Maxwell–Cattaneo–Vernotte (MCV) equation, parabolic, hyperbolic, and modified hyperbolic dual-phase-lag (DPL) equations. Using the integral transform technique, Laplace, and Fourier transforms, we provide a solution of the problem (Green’s function) in Laplace domain. The thermal double-strip problem, allowing the wave interference within the heat conductor, is considered. A numerical technique, based on the Durbin series for inverting Laplace transform and the trapezoidal rule for calculating an integral form of the solution in the double-strip case, is adopted to recover the solution in the physical domain. Finally, discussions for different non-Fourier heat transfer situations are presented. We compare among the speeds of hyperbolic heat transfer models and shed light on the concepts of flux-precedence and temperature-gradient-precedence, hallmarks of the lagging response idea. Otherwise, we emphasize the existence of a relationship between the waves speed and the time instant of interference onset, underlying the five employed heat transfer models.

Heat exchange structure design and overall performance analysis of double-concentrator solar thermal thruster

In this paper, the platelet heat exchanger in the thermal propulsion system of micro satellite with liquefied gas as propellant was designed, the complete gasification and stabilization scheme of propellant was proposed. The unsteady conjugate heat transfer (CHT) characteristics between the heat exchanger and gaseous propellant were analyzed, and the cumulative data of error estimation in the numerical simulation process was provided to ensure the credibility of the results. The CHT computational fluid dynamics (CFD) simulation of the platelet 3D model under steady-state conditions was carried out to find the empirical correlation between the average Nusselt number and the average Reynolds number. A simplified unsteady 1D model of heat exchanger was established by using the loose coupling method based on quasi steady flow field. The results show that the platelet structure could heat the working medium to more than 2379 K with the heat transfer efficiency of 86%, the outlet temperature and heat transfer efficiency of the heat exchanger were maintained at 1871 K and 69% in steady state when the mass flow rate was 1.14e-6 kg/s. The 1D model could accurately reflect the real heat transfer situation to a certain extent, the simulation error was less than 8.5% compared with the 3D model, and the calculation time was greatly shortened, making the adjustment of heat transfer strategy more convenient. Intermittent heat transfer method could keep the outlet gas temperature, thrust and specific impulse of the thruster at a high level to improve the performance of the system. Taking the nanosatellite with a total mass of 7.55 kg and a propellant mass of 0.25 kg as an example, when the duration of valve open time was 1.5s, the velocity increment of the satellite reached 72.21 m/s with the specific impulse of over 2400 m/s, which was twice than that of nanosatellites without heat exchange structure.

Chaotic control of the dynamical behavior of COVID-19 through the electromagnetic fields

Investigating the dynamical behavior of a system is an effective method to predict and control its future behavior. Studying the dynamic behavior of a virus can prevent the pathogenicity of a virus and save human lives during the disease epidemic. If the transmission of information from the virus genome to the environment is locked, the pathogenicity of the virus stops. Information transmission can be checked via the investigation of the spin information transport. In the current study, we have characterized the dynamical behavior of the virus by studying the spin transport through its RNA chain to estimate the information transfer path in the system. A voltage generator with adjustable frequency as a control system has been designed using the control theory of chaotic systems. Our aim is disturbing and reduces the transmitted information from viruses to the environment. The external stimuli can propel the system to the locked information transfer situation. Applying an external field noise with a specific frequency range (200–500 GHz) controlled through the external controller system can destroy the information transmitted by the virus to the environment. Disturbance intensity as a control parameter adjusts the external field frequency to push the system to the chaotic behavior which will be able to lock the information transfer and then prevent the spread of the epidemic.

Behaviour-directed interventions for problematic person transfer situations in two dementia care dyads: a single-case design study

BackgroundPersons with dementia living in nursing homes need assistance with moving and transfers; however, caregivers assisting persons with dementia in their daily person transfers report strain-related and complicated transfer-related behavioural problems. The reciprocity of complex dyadic transfer-related behaviours is affected by environmental factors, the health status of the person with dementia and the caregiver’s skills and knowledge. The aim of this study was to explore tailored interventions guided by a functional behaviour analysis for problematic person transfer situations in two dementia care dyads.MethodsThis study was a quasi-experimental single-case study with an A-B design. Tailored interventions were developed in a five-step model for functional behavioural analysis. The study was conducted in a dementia special care unit at a nursing home, and the inclusion criteria were caregivers’ experiences of physical strain and/or resistiveness to care, which led to complex transfer-related behaviour. Two care dyads were included. Transfer situations were video-recorded and evaluated with the Dyadic Interaction in Dementia Transfer Assessment Scale, Pain Assessment in Advanced Dementia Scale, and Resistiveness to Care Scale for Dementia of the Alzheimer’s Type. The caregiver experience was evaluated with study-specific items addressing caregiver self-efficacy, catastrophizing thoughts, perceived control, and perceived physical strain. Scorings were graphically displayed. The graphs were inspected visually to identify changes in trend, level, latency, and variability. Nonoverlap of all pairs (NAP), including 90% confidence intervals (CIs), was calculated to complement the visual inspection.ResultsVerbal and nonverbal discomfort decreased in care dyad 1, which mirrored the caregiver changes in adapting their actions to the needs of the person with dementia. High variability was seen in both the intervention and the baseline phases in care dyad 2. In both care dyads, caregiver transfer-related behaviour improved.ConclusionsThe results indicate that the transfer-related behaviours of the care dyad might be improved through a behaviour-directed intervention tailored to meet the care dyad´s needs. The small number of cases and observations limits the generalizability, and the results should be interpreted in consideration of the piloting approach of the study.

Thermo-hydraulic and entropy generation investigation of nano-encapsulated phase change material (NEPCM) slurry in hybrid wavy microchannel

PurposeThis study aims to capture the heat transfer and entropy generation characteristics of temperature-dependent nano-encapsulated phase change material (NEPCM) slurry in a hybrid wavy microchannel. In addition, the effect of substrate material combined with NEPCM slurry on conjugate heat transfer condition is captured for different microchannel heat sinks.Design/methodology/approachA novel “hybrid wavy microchannel” is proposed to enhance the overall heat transfer and reduce the pressure drop by combining wavy and raccoon geometry. NEPCM–water slurry is implied in the hybrid wavy, conventional wavy and raccoon microchannel. A user-defined function (UDF) is used to observe the effect of phase-change of paraffin material in thermophysical properties of NEPCM–water nanofluid. All three (hybrid, wavy, raccoon) microchannels are engraved on a rectangular substrate of 1.8 mm width (ωs) and 30 mm length (L), respectively. For hybrid, wavy and raccoon microchannel, waviness (γ) of 0.067 is selected for the investigation.FindingsThe result shows that NEPCM particle presence reduces the fluid domain temperature. The thermal performance of proposed Heat sink 2 is found better than the Heat sink 1. The effect of the geometrical modification, wall thermal conductivity, different volumetric concentrations of nanoparticles (ϕ ∼ 1 – 5%) and Reynolds number (Re ∼ 100 – 500) on thermodynamic irreversibility is also observed. Additionally, the effect of thermal and frictional entropy generation is reduced with a combination of NEPCM slurry and higher conductive material for all heat sinks.Practical implicationsA combination of NEPCM slurry with laminar flow microchannel cooling system emerged as a better alternative over other cooling techniques for higher power density devices such as microprocessors, electronic radar systems, aerospace applications, semiconductors, power electronics in modern electronic vehicles, high power lasers, etc.Originality/valueThe phase-change process of the NEPCM slurry is tracked under conjugate heat transfer in a hybrid wavy microchannel. Furthermore, the phase-change process of NEPCM slurry is captured with different heat sink materials (SS316, silicon and copper) under conjugate heat transfer situation for different heat sinks and concentrations (ϕ ∼ 1–5) of NEPCM.

The Complexity of Olfactory Art The Use of Scent as Concept and Context in the Work of Art

The sense of smell is a powerful sense that offers many possibilities. To speak of olfactory art, there must be the intention to use odour or olfaction as both context and concept of the work of art. For this, we speak about the terms Olfactory Context and Olfactory Concept. The Olfactory Context can be divided into the Intrinsic and Intentional Odour Values. The intrinsic odour value brings with it their significance, while the intentional odour value gives an extra meaning to a smell. In addition, the Olfactory Perception is part of the Olfactory Concept of the artwork. To perceive this, the smell must be transferred to the spectator. The way in which an odour is transferred in a work largely determines how the smell is interpreted in relation to the work. The odour transfer and odour situation determine how an odour gets to the viewer. We call these methods of odour transfer Olfactory Transfers and divide them into five categories: Flowers, Smell Devices, Scent Spaces, Time and Translations. In most cases, Olfactory Transfers are used in crossovers. Together with the various possibilities of using the Olfactory Context, they also demonstrate the Complexity of Olfactory Art. The 1st Olfactory Art Manifest explains the differences in olfactory art, while the 2nd Olfactory Art Manifest demonstrates the Complexity of Olfactory Art.

Central liquid jet emanating from an impacting drop on superheated laser-ablated surfaces

Drop impacts on superheated textured surfaces have been studied extensively due to the unique characteristics arising from the roughness, which can be controlled through texturing features. The characteristics include novel modifications of the wettability and boiling regimes. The increased roughness of a textured surface also results in an unusual phenomenon where a central liquid jet emanates from an impinging drop. The central jet can interfere with the designated objective of textures or can be used in other applications, but it has rarely been reported and analyzed. Therefore, this study provides detailed and quantitative information on the central jet. With sufficient spatial and temporal resolutions, the impact and boiling behaviors including the central jet are clearly acquired and explained. The time-resolved height and speed of the jets are correlated to varying impact conditions such as the impact momentum of droplets, roughness and temperature of the surfaces. To understand and estimate the origin of the central jet, we also analyze several key findings, such as the motion of a cluster of vapor bubbles and the rim pattern of contact boiling. In addition, a hypothetical mechanism of the jet formation is proposed based on experimental evidence and a simplified heat transfer situation.

Nanofluids dynamic viscosity evolution using high-frequency acoustic waves: Application applied for droplet evaporation

Many interests are shown on nanofluids as it’s suitable for cooling applications. Knowing the physical properties of nanofluids such as viscosity plays a key role in practical heat transfer situations. The main goal of this work is to measure the dynamic viscosity of Gold nanofluids during sessile droplets evaporation, at ambient temperature, based on ultrasonic high-frequency acoustic waves (1 GHz). So, we have developed the high-frequency acoustic transducers, for longitudinal and shear waves, located at the bottom side of the silicon substrate. This method has access to characterize the liquid/solid interface (Droplet/Silicon). Due to viscoelastic losses (one of the causes of attenuation), the attenuation (attenuation in fluids about 220 dB/mm) of the sound energy produced by nanofluid generates a complex form for the mechanical impedance of the sessile droplet of nanofluid. The measured echoes diagram represented by amplitude and phase angle were obtained using a Network Analyzer. The complexity of the nanofluid for the shear signal wave has a direct relation between the attenuation and the viscosity and as a result, an online variation in the shear viscosity of a droplet contains 4% Cv gold nanoparticles were extracted throughout the evaporation process. At the same time, a new micromechanical model developed by FreeFem++ software was provided to compare the results obtained experimentally. This model has been validated to be used to calculate the viscosity of nanofluids.

The diagnostic value of chest CT and MRI for lymph node metastasis of thoracic esophageal cancer

Objective To compare the clinical value of chest CT and Magnetic Resonance Imaging (MRI) in the diagnosis of lymph node metastasis of thoracic esophageal cancer. Methods A retrospective analysis of 90 patients with thoracic esophageal cancer lymph node metastasis diagnosed and treated in our hospital from July 2015 to June 2019. All patients underwent chest CT and MRI scans after admission, and the lesion tissue samples were taken for pathological examination after surgery. Physical examination, with pathological diagnosis results as the gold standard, analyze the sensitivity and specificity of chest CT and MRI. Results The sensitivity, specificity, positive predictive value, and negative predictive value of MRI scan was 88.73%, 94.74%, 98.44%, and 69.23%, respectively, which were higher than 69.01%, 52.63%, 84.48%, and 31.25% of the chest CT scan. In the distribution of lymph node metastasis, the middle of the thorax was the largest, and the proportions of the upper, middle, and lower thoraxes were 26.67%, 60.00%, and 13.33%, respectively. The uppermost mediastinal and paratracheal lymph nodes had the largest metastases in the upper thorax, the paratracheal and subcarinal lymph nodes in the middle thoracic segment had the most metastasis, and the next to the cardia and left gastric artery lymph nodes in the lower thorax had the largest metastases. The accuracy of MRI diagnosis is higher than that of chest CT. Conclusion Both chest CT and MRI can diagnose lymph node metastasis of thoracic esophageal cancer. The diagnostic value of MRI in diagnosing lymph node metastasis of thoracic esophageal cancer is better than chest CT. The diagnostic accuracy of MRI in each part of the lymph node is higher than that of chest CT, which can show the lymph nodes more clearly in transfer situation. 摘要： 目的 比较胸部计算机断层扫描 (computer tomography, CT) 和磁共振成像 (magnetic resonance imaging, MRI) 判断胸段食管癌淋巴结转移的临床价值。 方法 回顾性分析2015年7月一2019年6月在我院诊治的胸段食管癌淋 巴结转移患者90例, 所有患者在入院后均采用胸部CT和MRI平扫及增强扫描, 并在手术后对病灶组织标本进行病 理学检测, 以病理诊断结果为金标准, 分析胸部CT和MRI灵敏度和特异度。 结果 MRI扫描, 灵敏度为88.73%, 特 异度为94.74%, 阳性预测值为98.44%, 阴性预测值为69.23%, 高于胸部CT扫描的69.01%、52.63%、84.48%、31.25%。淋巴结转移分布中, 胸中段最多, 胸上段、胸中段、胸下段所占比例分别为26.67%、60.00%、13.33%, 胸上段中 最上纵隔和气管旁淋巴结转移最多, 胸中段气管旁、隆突下淋巴结转移最多, 胸下段贲门旁、胃左动脉旁淋巴结转移最 多, MRI诊断准确率高于胸部CT。 结论 胸部CT、MRI均能够诊断出胸段食管癌淋巴结转移, MRI诊断胸段食管癌 淋巴结转移的诊断价值优于胸部CT, MRI在胸段淋巴结各部位的诊断准确率高于胸部CT, 能够更清晰显示淋巴结的 转移情况。

Use of knowledge pieces and context features during the transfer process in physics tasks

ABSTRACT In this article, we present a qualitative study examining students’ thoughts and strategies while transferring concepts about energy in physics. We include theoretical approaches of existing transfer research and findings from think-aloud interviews with 20 students of different ages and school levels to develop a framework for analysing the transfer process. The results of both traditional transfer studies and modern approaches, such as the ‘Actor-Oriented Transfer perspective’ (AOT) and ‘Coordination Class Theory’ (CCT), are regarded as a theoretical foundation for the framework. Our empirical data involves the statements of students solving a physics task with questions regarding the energy concept, which we used to inductively derive categories for our framework. We conclude that the transfer process is highly individual and that our framework can make this process visible. Knowledge can be transferred with or without a relation to the contextual features of the transfer situation, and it is possible that students describe the context situation itself without relating it to their existing knowledge pieces. Finally, we found four metacognitive strategies that students use while transferring their knowledge. The findings will help teachers to focus on the applicability of knowledge and on practising the use of transfer strategies.

China's carbon emissions from the electricity sector: Spatial characteristics and interregional transfer.

As a major carbon emitter, the electricity sector is crucial to the realization of China's emission reduction objectives. Existing studies focus mostly on the influencing factors, emission efficiency and low carbon development of carbon emissions in the electricity sector. Missing from the literature is an analysis of spatial characteristics of carbon emissions and the embodied carbon emission transfer caused by the separation of electricity production and consumption, which is the basis for assigning the responsibility for emission reduction. Thirty provinces in China were taken as research objects, and Moran's I index was adopted to analyze the spatial characteristics of the electricity sector's carbon emissions and carbon emission intensity. Based on multiregional input-output tables, we compared the transfer situation of China's provincial electricity carbon emissions in 2010 and 2015. The results demonstrate that, from 2010 to 2015, the electricity carbon emissions in 20 provinces increased, whereas the carbon emission intensity in 21 provinces decreased. Carbon emissions and carbon emission intensity of electricity in most provinces demonstrate positive spatial clustering characteristics. The total amount of carbon emission transfer in the electricity sector increased from 421.22 million tons in 2010 to 581.369 million tons in 2015, the number of net transfers out of areas increased from 13 to 15, and the number of net transfers into areas decreased from 16 to 15. The active degree of carbon emission transfer reveals the eastern region > the central region > the western region. Different emission reduction policies should be formulated based on the difference in resource endowment between the north and south. Provinces that transferred out large amounts of electricity carbon emissions should take greater responsibility for emission reduction. Integr Environ Assess Manag 2022;18:258-273. © 2021 SETAC.

The conductivity and redox properties of pyrolyzed carbon mediate methanogenesis in paddy soils with ethanol as substrate

Pyrolyzed carbon such as biochar and activated carbon could influence the methanogenesis in paddy soil, which is an important process controlling methane emission. Different electrochemical properties of pyrolyzed carbon may be involved in methanogenesis, such as conductivity and redox activity. However, their different roles have not been thoroughly illustrated before. In this study, we identified the roles of pyrolyzed carbon redox property and electron conductivity in methanogenesis with ethanol as a substrate, by comparing pyrolyzed carbon samples with sequential change of electrochemical properties. Right after the addition, pyrolyzed carbon with highest electron donating capacity (0.85 mmol/g) promoted the methane generation by 33.3%; while, other pyrolyzed carbon with higher electron accepting capacity and lower electron donating capacity than B4 inhibited the methane generation. The relative abundance of electroactive bacteria and certain methanogens increased with the pyrolysis temperature. The strict linear relationship between electroactive bacteria/certain methanogens and cyclic voltammetry peak currents of paddy soil implied that microbial structure was altered due to the improved the electron transfer situation by the electron shuttle ability of pyrolyzed carbon. This study could deepen our understanding about the effect of pyrolyzed carbon on methanogenesis process.

Stochastic Model for Energy Propagation in Disordered Granular Chains

Energy transfer is one of the essentials of mechanical wave propagation (along with momentum transport). Here, it is studied in disordered one-dimensional model systems mimicking force-chains in real systems. The pre-stressed random masses (other types of disorder lead to qualitatively similar behavior) interact through (linearized) Hertzian repulsive forces, which allows solving the deterministic problem analytically. The main goal, a simpler, faster stochastic model for energy propagation, is presented in the second part, after the basic equations are re-visited and the phenomenology of pulse propagation in disordered granular chains is reviewed. First, the propagation of energy in space is studied. With increasing disorder (quantified by the standard deviation of the random mass distribution), the attenuation of pulsed signals increases, transiting from ballistic propagation (in ordered systems) towards diffusive-like characteristics, due to energy localization at the source. Second, the evolution of energy in time by transfer across wavenumbers is examined, using the standing wave initial conditions of all wavenumbers. Again, the decay of energy (both the rate and amount) increases with disorder, as well as with the wavenumber. The dispersive ballistic transport in ordered systems transits to low-pass filtering, due to disorder, where localization of energy occurs at the lowest masses in the chain. Instead of dealing with the too many degrees of freedom or only with the lowest of all the many eigenmodes of the system, we propose a stochastic master equation approach with reduced complexity, where all frequencies/energies are grouped into bands. The mean field stochastic model, the matrix of energy-transfer probabilities between bands, is calibrated from the deterministic analytical solutions by ensemble averaging various band-to-band transfer situations for short times, as well as considering the basis energy levels (decaying with the wavenumber increasing) that are not transferred. Finally, the propagation of energy in the wavenumber space at transient times validates the stochastic model, suggesting applications in wave analysis for non-destructive testing, underground resource exploration, etc.

Linear and nonlinear triple diffusive convection in the presence of sinusoidal/non-sinusoidal gravity modulation: A comparative study

The non-uniform vertical vibrations (gravity modulation) or g-jitter or time-periodic body force, can be realized by oscillating the system vertically. The time periodic variations are considered to vary sinusoidally (trigonometric cosine) or non-sinusoidally (square, sawthooth and triangular) to study three-component convection in a Newtonian fluid using linear and non-linear analyses. In the linear theory, the expressions for the Rayleigh number and the correction Rayleigh number are obtained by using a regular perturbation method. The eigen value is obtained by adopting the classical Venezian approach. The generalized Lorenz model is derived using a Fourier series with additional modes and under the assumption of the Boussinesq approximation and small-scale convection motion. The resulting non-autonomous Lorenz model is solved numerically to quantify the heat and mass transports. The results are considered against the background of the results of no modulation. Study reveals that all the four types of gravity modulation delay the onset of convection and thereby lead to the diminished heat transfer situation. It is also found that in the case of trigonometric type of gravity modulation heat and mass transports are between those of the cases of triangular and square types. The results in respect of saw-tooth and triangular wave modulations are identical.

Steady-State Fluid-Solid Mixing Plane to Replace Transient Conjugate Heat Transfer Computations during Design Phase

The demand for increased turbomachinery performance, both, towards higher pressures and temperatures, leads to high thermal-loads of specific components and can critically affect mechanical integrity. In the particular case of rotating-disk configurations, like the back-side of wheels or in cavities, a very efficient way for cooling is jet impingement. An example for this situation are high pressure-ratio turbochargers, where cooling of the impeller disk (back wall) is introduced to achieve tolerable thermal loads. From the physical point of view, jet impingement on a rotating wall generates an unsteady heat transfer situation. On the other end, accurate values of time-averaged temperatures would be sufficient for design purposes. In general, obtaining circumferentially time-averaged solutions requires transient analysis of the conjugate heat transfer (CHT) process to account for the mean effect of jet cooling on solids. Such analysis is computationally expensive, due to the difference in information propagation time-scale for the solid and the fluid. In this paper, a new approach to directly compute circumferentially time-averaged (i.e., steady-state) temperature distributions for rotating-disk CHT problems is presented based on an adaption of the well known fluid-fluid mixing plane approach.

Predicted influence of overhead transmission lines on land-use transfer: A case study on landscape and famous scenery

Taking Baihetan—Jiangsu ±800kV UHVDC power transmission project as an example, the influence of tower foundation on land-use types and functions were predicted using ArcGIS platform and eCognition Developer. Through the construction of land-use transfer matrix analysis, the change of land-use transfer situation and structure were discussed. Our results showed that the forest transfer intensities (RT) of Tangya River Scenic spot and Three Gorges Scenic area were 0.64 and 1.49 respectively, the RT of bushes and grasses in Tangya River Scenic spot and Three Gorges Scenic area were 1.01 and 0.37. The RT of forest, bushes and grasses were both not high. The permanent occupation area of project was all transferred into building land, the construction land dynamics degrees (KT) of Tangya River Scenic spot and Three Gorges Scenic area were +0.40% and +0.031% respectively, which were both low. Thus we drew a conclusion that the project construction would have a slight impact on land use pattern and function and would not affect the overall ecological function and structure of landscape and famous scenery.

Conjugate effect on flow boiling instability in wavy microchannel

Three-dimensional numerical study on two-phase flow boiling in rectangular microchannel with wavy vertical wall configuration is considered that can be utilized for heat dissipation in high flux electronics devices. Straight and wavy microchannels are considered for comparison and analysis. Under conjugate heat transfer situation, effect of flow boiling instability in straight and wavy microchannel is numerically studied using water as the working fluid. Behaviour of bubble growth rate and two-phase flow pattern in straight and wavy microchannel are investigated for a wide range of parameters such as waviness (γ ~ 0 - 0.267), substrate thickness to channel height ratio (δsf ~ 1 and 5), wall to fluid conductivity ratio (ksf ~ 22 - 646), and mass flux (G ~ 118 - 590 kg/m2s). It is found that smaller bubbles are formed in wavy microchannel while confined and elongated bubbles are formed in straight microchannel which often causes flow clogging and premature dryout. The work also presents a comparative analysis between single-phase and two-phase flow boiling cooling technique in straight and wavy microchannel under same geometrical parameters and applied heat flux.

Study of the effects of three types of time-periodic vertical oscillations on the linear and nonlinear realms of Rayleigh-Bénard convection in hybrid nanoliquids

In the paper, the effect of time-periodic gravity modulation with trigonometric sine, triangular, and square waves-forms on Rayleigh Bénard convection in water-alumina nanoliquids and water-alumina-copper hybrid nanoliqiuds is studied by using a single-phase model. Using a perturbation method, linear stability analysis is performed for all the three wave-forms. A generalized Lorenz model that has the influence of nanoliquids and modulation incorporated in it is derived using a truncated Fourier series representation. The Lorenz model is then transformed into a Ginzburg-Landau model using the method of multiscales, and the solution is used to study heat transport. For trigonometric sine, triangular and square wave-forms of modulations comparison are made on their effect on the onset of convection and the heat transport. The linear stability analysis reveals that the critical Rayleigh number obtained in the case of a triangular wave-form is less compared to the value obtained in the cases of trigonometric sine and square wave-forms. This leads to an enhanced heat transfer situation in the case of triangular wave-form compared to that in the other two wave-forms. It is also found that such an enhancement in heat transport increases with amplitude and decreases with the modulation frequency. Thus, the modulation is found to be a regulating mechanism on heat transport. Further, it is observed that water-alumina-copper facilitates maximum heat transport compared to that by water-alumina and water, leading to the conclusion that hybrid nanoliquids facilitate enhanced heat transport compared to that by mono nanoliquids.

Knowledge Transfer Across Types of Assignments: Case study of an International Oil Company

The principal objective of this paper is to explore how using different sorts of international assignments (short-term expatriation, long-term expatriation, short-term inpatriation) enable the headquarters (HQ) and ancillary branches to transfer an assortment of knowledge types (procedural, declarative, axiomatic, and relational knowledge) from the HQ to their ancillaries, through the period of assignment. The current study used a qualitative approach based on the data collection strategy of semi-structured interviews with 20 partakers with standings of international assignment (IA). The content analysis methodology was managed to analyze and codify the interviews. The findings reveal that every single kind of assignment acts as a special knowledge transfer situation. The principal benefaction of our study is that it delivered a more precise understanding of international assignments as knowledge transfer situations than any research in precedence. While the contributions of this study have been salient, certain limitations pave the way for extensive research possibilities. To begin with, this paper lays emphasis on a large organisation in the Oil and Gas sector in three countries, UK (the HQ), Oman and UAE, which limits generalization of the findings. The paper reviews the implications of selecting IA to transfer the various types of knowledge. We achieve this by distinguishing the knowledge convey role of international assignments across different types of assignments, types of knowledge, and the direction and timing of knowledge transfer through or following the international assignment. First this paper is necessary to analyze the success of knowledge transfer and IA and ascertain their application. To the best of our knowledge, this research one of the rare studies that include the engineer’s perspective in the global Oil and Gas sector. This umbrella approach aids in better understanding IA and knowledge transfer.