A Comparative Study of Heat Transfer Coefficients for Film Condensation

Film condensation heat transfer has wide applications in a variety of industrial systems. A number of film condensation heat transfer correlations (FCHTCs) have been proposed. However, their predictions are often inconsistent. This paper presents a comparative study of existing FCHTCs. Totally 1214 experimental data points are obtained from 10 published papers, and 14 FCHTCs are reviewed, among which four correlations are used for horizontal flow outside smooth tubes, three for flow on vertical surfaces of plates or tubes, two for flow inside smooth tubes either vertically or horizontally, and five for horizontal flow inside smooth tubes. 13 FCHTCs are compared with the experimental data. There are three FCHTCs for horizontal flow inside smooth tubes having a mean absolute relative deviation (MARD) less than 26%, among which the best one has an MARD of 22.2%. More efforts should be made to develop better correlations.Key words: Correlation; Heat transfer; Film; Condensatio

Create and Find Flatness: Building Flat Training Spaces in Advance for Continual Learning

Catastrophic forgetting remains a critical challenge in the field of continual learning, where neural networks struggle to retain prior knowledge while assimilating new information. Most existing studies emphasize mitigating this issue only when encountering new tasks, overlooking the significance of the pre-task phase. Therefore, we shift the attention to the current task learning stage, presenting a novel framework, C&F (Create and Find Flatness), which builds a flat training space for each task in advance. Specifically, during the learning of the current task, our framework adaptively creates a flat region around the minimum in the loss landscape. Subsequently, it finds the parameters' importance to the current task based on their flatness degrees. When adapting the model to a new task, constraints are applied according to the flatness and a flat space is simultaneously prepared for the impending task. We theoretically demonstrate the consistency between the created and found flatness. In this manner, our framework not only accommodates ample parameter space for learning new tasks but also preserves the preceding knowledge of earlier tasks. Experimental results exhibit C&F's state-of-the-art performance as a standalone continual learning approach and its efficacy as a framework incorporating other methods. Our work is available at https://github.com/Eric8932/Create-and-Find-Flatness.Comment: 10pages, ECAI2023 conferenc

Growth responses of Ulva prolifera to inorganic and organic nutrients: Implications for macroalgal blooms in the southern Yellow Sea, China

International audienceThe marine macrophyte Ulva prolifera is the dominant green-tide-forming seaweed in the southern Yellow Sea, China. Here we assessed, in the laboratory, the growth rate and nutrient uptake responses of U. prolifera to different nutrient treatments. The growth rates were enhanced in incubations with added organic and inorganic nitrogen [i.e. nitrate (NO3−), ammonium (NH4+), urea and glycine] and phosphorus [i.e. phosphate (PO43−), adenosine triphosphate (ATP) and glucose 6-phosphate (G-6-P)], relative to the control. The relative growth rates of U. prolifera were higher when enriched with dissolved organic nitrogen (urea and glycine) and phosphorus (ATP and G-6-P) than inorganic nitrogen (NO3− and NH4+) and phosphorus (PO43−). In contrast, the affinity was higher for inorganic than organic nutrients. Field data in the southern Yellow Sea showed significant inverse correlations between macroalgal biomass and dissolved organic nutrients. Our laboratory and field results indicated that organic nutrients such as urea, glycine and ATP, may contribute to the development of macroalgal blooms in the southern Yellow Sea

PreDiff: Precipitation Nowcasting with Latent Diffusion Models

Earth system forecasting has traditionally relied on complex physical models that are computationally expensive and require significant domain expertise. In the past decade, the unprecedented increase in spatiotemporal Earth observation data has enabled data-driven forecasting models using deep learning techniques. These models have shown promise for diverse Earth system forecasting tasks but either struggle with handling uncertainty or neglect domain-specific prior knowledge, resulting in averaging possible futures to blurred forecasts or generating physically implausible predictions. To address these limitations, we propose a two-stage pipeline for probabilistic spatiotemporal forecasting: 1) We develop PreDiff, a conditional latent diffusion model capable of probabilistic forecasts. 2) We incorporate an explicit knowledge control mechanism to align forecasts with domain-specific physical constraints. This is achieved by estimating the deviation from imposed constraints at each denoising step and adjusting the transition distribution accordingly. We conduct empirical studies on two datasets: N-body MNIST, a synthetic dataset with chaotic behavior, and SEVIR, a real-world precipitation nowcasting dataset. Specifically, we impose the law of conservation of energy in N-body MNIST and anticipated precipitation intensity in SEVIR. Experiments demonstrate the effectiveness of PreDiff in handling uncertainty, incorporating domain-specific prior knowledge, and generating forecasts that exhibit high operational utility.Comment: Technical repor

Feasibility of a mean platelet volume standard:an international council for standardization in hematology (ICSH) inter-laboratory study

We have evaluated a commercial-fixed porcine platelet preparation (with and without added fixed human red blood cells (RBC)) for the potential standardization of mean platelet volume (MPV) measurements. The standards (Biotechne) were distributed internationally to 19 laboratories including all major hematology instrument manufacturers and academic/pathology laboratories. Overall, the standards demonstrated excellent stability up to 1 month within both MPV values and platelet counts when stored at 4°C. The presence of RBC significantly increased the platelet count and MPV values compared to platelets alone. However, as expected, there were differences in MPV values between different instruments and manufacturers. MPV values were also significantly higher in the whole blood standard compared to the platelet standard in the majority of instruments except with some instruments, where MPV values were significantly higher in the platelet only preparation. To further investigate this phenomenon, two different Platelet MPV preparations (with low and high MPV) in combination with 3 different RBC MCV preparations (with low, normal or high MCVs) were tested to try and further elucidate how RBC populations may impact upon platelet analysis (count, MPV, and PDW) using a single impedance analyzer. Both MPV and MCV values showed good stability over the course of the study for up to 50 days. As expected, the RBC preparation with the lowest MCV had the greatest impact on the MPV. However, this was not observed with an increase in MCV of the RBC or by a larger MPV of the platelet population. To further understand how different gating strategies may also influence results, we investigated the effect of either fixed or floating gate strategies upon MPV raw data from patient samples in a single impedance analyzer. Overall, it was clear that floating and fixed gate strategies also significantly impact upon MPV values. In conclusion, we have demonstrated the potential of an MPV standard with good stability characteristics for calibrating and comparing full blood counters that use different analysis principles, gating and MPV calculations. This may facilitate future instrument calibration and harmonization of results between different technologies

The IRE1α-XBP1 Pathway of the Unfolded Protein Response Is Required for Adipogenesis

SummarySignaling cascades during adipogenesis culminate in the expression of two essential adipogenic factors, PPARγ and C/EBPα. Here we demonstrate that the IRE1α-XBP1 pathway, the most conserved branch of the unfolded protein response (UPR), is indispensable for adipogenesis. Indeed, XBP1-deficient mouse embryonic fibroblasts and 3T3-L1 cells with XBP1 or IRE1α knockdown exhibit profound defects in adipogenesis. Intriguingly, C/EBPβ, a key early adipogenic factor, induces Xbp1 expression by directly binding to its proximal promoter region. Subsequently, XBP1 binds to the promoter of Cebpa and activates its gene expression. The posttranscriptional splicing of Xbp1 mRNA by IRE1α is required as only the spliced form of XBP1 (XBP1s) rescues the adipogenic defect exhibited by XBP1-deficient cells. Taken together, our data show that the IRE1α-XBP1 pathway plays a key role in adipocyte differentiation by acting as a critical regulator of the morphological and functional transformations during adipogenesis

Microstructure and performance of rare earth element-strengthened plasma-facing tungsten material

Pure W and W-(2%, 5%, 10%) Lu alloys were manufactured via mechanical alloying for 20 h and a spark plasma sintering process at 1, 873 K for 2 min. The effects of Lu doping on the microstructure and performance of W were investigated using various techniques. For irradiation performance analysis, thermal desorption spectroscopy (TDS) measurements were performed from room temperature to 1, 000 K via infrared irradiation with a heating rate of 1 K/s after implantations of He+ and D+ ions. TDS measurements were conducted to investigate D retention behavior. Microhardness was dramatically enhanced, and the density initially increased and then decreased with Lu content. The D retention performance followed the same trend as the density. Second-phase particles identified as Lu2O3 particles were completely distributed over the W grain boundaries and generated an effective grain refinement. Transgranular and intergranular fracture modes were observed on the fracture surface of the sintered W-Lu samples, indicating some improvement of strength and toughness. The amount and distribution of Lu substantially affected the properties of W. Among the investigated alloy compositions, W-5%Lu exhibited the best overall performance