The effect of confinement on the development of an axisymmetric wall jet in confined jet impingement

Impinging jets have been widely used in the industry for cooling, heating, drying and many other purposes due to their excellent level of mass and heat transfer capacities. When issued into a confinement gap fully filled with working liquid, which is a typical configuration for the compact cooling devices designed to handle the extremely high heat fluxes generated by continuously working electronic components, they are classified as submerged confined impingement jets. Though the complicated flow field induced by the jet has attracted enormous amount of research efforts from heat transfer as well as fluid dynamics points of view, many key questions still remain unanswered. The present work reports a detailed experimental study of the flow field surrounding an axisymmetric, confined, impingement jet using stereo particle image velocimetry (SPIV). The experiments are conducted at three different orifice-to-plate spacings (2, 4 and 8 jet diameters) across Reynolds number ranging from 1000 to 9000. A maximum spatial resolution of 25 μm is achieved and the temporal resolution of the measurement remains 750 Hz. Special attention has been paid to the development of the triple-layered wall-jet with incomplete self-similarity. The jet core length and expansion angle for the vertical impingement jet has been calculated and presented. At small confinement height, the recirculating vortical structure has been found to strongly affect the wall-jet development. These flow field measurements and analysis will serve to inform a variety of practical applications in which impinging jets are used

Functional characterization of clade-I HIPP proteins from Arabidopsis thaliana interacting with cytokinin-catabolizing CKX enzymes

The plant hormone cytokinin controls various processes in plant development and responses to environmental stresses. Cytokinin degradation is catalyzed by a group of CKX enzymes. Cellular levels of these proteins significantly impact the cytokinin homeostasis in plants and it is, therefore, important to understand the mechanisms regulating their activities. In this study, several CKX-interacting proteins, belonging to a plant-unique protein family (HIPP), were molecularly characterized and their biological function elucidated, particularly in respect to the regulation of cytokinin homeostasis. In the first part of this work, the molecular basis of the CKX-HIPP interaction, such as the essential interaction motifs, interaction specificity, and the subcellular compartmentation of the CKX-HIPP complex, were investigated. Interaction assays performed in yeast and in planta revealed protein-protein interactions between specific members of the CKX and HIPP protein families. CKX1 interacted with HIPP proteins from the phylogenetic cluster I and III, but not other members of the family. The analyzed cluster I-HIPP proteins interacted additionally with most CKX proteins targeted to the secretory system but did not interact with the cytosolic CKX7 isoform. The CKX1-HIPP7 interaction required the prenylation motif at the C-terminus of HIPP7, implying that the lipid modification mediates the CKX-HIPP interaction. In addition, the tested HIPP proteins were found to form homodimers, which required both the functional prenylation and HMA domains, suggesting that metal binding could mediate the HIPP homodimerization. The Arabidopsis CKX1 protein, a case example in this study, has been shown to be a type II membrane protein that localizes predominantly to the ER. However, the subcellular localization studies in this work revealed that HIPP1, HIPP5 and HIPP7 are localized apparently outside of the secretory system, predominantly in the cytosol and nucleus. To address this discrepancy, bimolecular fluorescence complementation (BiFC) assays were performed. The fluorescence of the BiFC CKX1/HIPP7 complex clearly showed that the interaction occur at the cortical and perinuclear ER. Moreover, a strong BiFC signal mainly localized in the nucleus and cytosol was detected for the CKX1/HIPP1 pair. These results suggest that CKX1 in the detected complexes represents a protein form that was relocated to the cytosolic site of the ER membrane. The second part of this work aimed to uncover the biological function of the identified HIPP proteins, especially in respect to their potential role in regulating CKX protein levels and cytokinin responses in Arabidopsis. The HIPP-overexpressing plants displayed cytokinin-related phenotypic changes and were hypersensitive to cytokinin. This was correlated with an increased cytokinin activity in these plants. It could be further shown that HIPP proteins differentially affected the abundance of the CKX1 protein. Given that CKX1 has been previously shown to be an ERAD substrate protein, it is proposed that the analyzed HIPP proteins might play a role during the retrotranslocation of CKX proteins from ER into the cytosol or during their cytosolic proteasomal degradation. It is hypothesized that the increased cytokinin activity displayed by HIPP-overexpressing plants is due to reduced levels of CKX proteins in the ER, which results in more cytokinin being sensed by the AHK cytokinin receptors localized in this compartment. Analysis of the concentration of other phytohormones or key genes determining their biosynthesis revealed that HIPP-overexpression resulted in the accumulation of stress-related hormones, i.e. ABA and SA, and downregulation of genes related to GA biosynthesis. These changes probably accounted for the enhanced drought tolerance and delayed onset of flowering of the HIPP-overexpressing plants. These data suggest that HIPPs may have broader biological activity beyond the regulation of CKX. Additionally, the effects of hipp loss-of-function mutations and the expression patterns of the analyzed HIPP genes were investigated in this work. In comparison to the phenotypic changes of the HIPP-overexpressing plants, hipp single and double mutants did not display obvious phenotypic changes, suggesting a higher degree of functional redundancy among the cluster I HIPP genes in controlling cytokinin responses and plant development. The HIPP genes were found to be expressed in distinct tissues, including mainly root and shoot apical meristems, and vascular tissues. Interestingly, HIPP transcript levels were repressed by exogenous cytokinin applications, suggesting a regulatory feedback loop between cytokinin and analyzed HIPP genes

Design and implementation of remote meter reading system in smart grid

Every progress of science and technology will drive the reform of other undertakings, with the continuous improvement of computer network technology, power grid operation has also appeared technical reform, the outstanding performance is the operation and use of remote meter reading system. Through the analysis and contrast of the relevant data, the paper specifi cally discusses the design and implementation of the remote meter reading system in the smart grid, hoping that through the introduction of this paper can eff ectively drive the reform of the operation of the grid, improve the stability, security and reliability of the operation of China’s power grid

Design and implementation of comprehensive sign monitor based on Internet +

Along with our country has accelerated into the aging society, the majority of the elderly medical and health problems, the shortage of medical resources, diffi cult to see a doctor, long cycle and other problems become increasingly prominent. In order to provide the elderly with better and more convenient health status monitoring, this paper proposes a comprehensive sign monitor based on Internet +. In this paper, the overall design framework of the comprehensive signs monitor is studied, STM32 processor is used as the CPU, and the physiological signifi cance and measurement methods of each physical sign parameter (blood oxygen, blood pressure, body temperature, etc.) are introduced. It allows doctors to obtain patients’ health data remotely, analyze patients’ health status, and achieve timely prevention and diagnosis and treatment, which provides great convenience for doctors and patients

ContraNorm: A Contrastive Learning Perspective on Oversmoothing and Beyond

Oversmoothing is a common phenomenon in a wide range of Graph Neural Networks (GNNs) and Transformers, where performance worsens as the number of layers increases. Instead of characterizing oversmoothing from the view of complete collapse in which representations converge to a single point, we dive into a more general perspective of dimensional collapse in which representations lie in a narrow cone. Accordingly, inspired by the effectiveness of contrastive learning in preventing dimensional collapse, we propose a novel normalization layer called ContraNorm. Intuitively, ContraNorm implicitly shatters representations in the embedding space, leading to a more uniform distribution and a slighter dimensional collapse. On the theoretical analysis, we prove that ContraNorm can alleviate both complete collapse and dimensional collapse under certain conditions. Our proposed normalization layer can be easily integrated into GNNs and Transformers with negligible parameter overhead. Experiments on various real-world datasets demonstrate the effectiveness of our proposed ContraNorm. Our implementation is available at https://github.com/PKU-ML/ContraNorm.Comment: ICLR 202