Energy saving potential of a counter-flow regenerative evaporative cooler for various climates of China: Experiment-based evaluation

© 2017 Recently there has been growing interest in regenerative evaporative coolers (REC), which can reduce the temperature of the supply air to below the wet-bulb of intake air and approach its dew-point. In this paper, we designed, fabricated and experimentally tested a counter-flow REC in laboratory. The REC's core heat and mass exchanger was fabricated using stacked sheets composed of high wicking evaporation (wickability of available materials was measured) and waterproof aluminium materials. The developed REC system has a much higher cooling performance compared to conventional indirect evaporative cooler. However, the decision to use the REC for China buildings depends on a dedicated evaluation of the net energy saved against the capital expended. Such an evaluation requires the hourly-based data on the availability of cooling capacity provided by the REC for various climates. The paper used an experiment-based method to estimate the cooling capacity and energy savings provided by the proposed REC for China's various climates. By using the experimental results and regional hourly-based weather data, the energy saving potential of the REC against an equivalent-sized mechanical air conditioner alone was analysed. The results indicate that, for all selected regions, the REC could reduce 53–100% of cooling load and 13–58% of electrical energy consumption annually

Experimental Study on the Energy Performance of PV-HP Water Heating System

AbstractMany studies have found that the decrease of photovoltaic (PV) cell temperature would increase the solar-to-electricity conversion efficiency. This paper provided a study on the thermal and electrical performance of PV panel with active cooling by attaching heat pipes beneath the PV panel, building up a PV-heat pipe (HP) combined system. The effect of solar radiation, inlet water temperature and water flow on the electrical and thermal efficiencies of the system were studied. The results showed that the thermal efficiency of the heat pipe PV/thermal (PV/T) solar water heating system decreased with the increasing inlet water temperature and water flow, and increased with the increasing solar radiation; the electrical efficiency decreased with increasing solar radiation, inlet water temperature and water flow

Numerical investigation of the energy performance of a guideless irregular heat and mass exchanger with corrugated heat transfer surface for dew point cooling

© 2016 The Author(s) The paper presents an investigation into the energy performance of a novel irregular heat and mass exchanger for dew point cooling which, compared to the existing flat-plate heat exchangers, removed the use of the channel supporting guides and implemented the corrugated heat transfer surface, thus expecting to achieve the reduced air flow resistance, increased heat transfer area, and improved energy efficiency (i.e. Coefficient of Performance (COP)) of the air cooling process. CFD simulation was carried out to determine the flow resistance (K) factors of various elements within the dry and wet channels of the exchanger, while the ‘finite-element’ based ‘Newton-iteration’ numerical simulation was undertaken to investigate its cooling capacity, cooling effectiveness and COP at various geometrical and operational conditions. Compared to the existing flat-plate heat and mass exchangers with the same geometrical dimensions and operational conditions, the new irregular exchanger could achieve 32.9%–37% higher cooling capacity, dew-point and wet-bulb effectiveness, 29.7%–33.3% higher COP, and 55.8%–56.2% lower pressure drop. While undertaking dew point air cooling, the irregular heat and mass exchanger had the optimum air velocity of 1 m/s within the flow channels and working-to-intake air ratio of 0.3, which allowed the highest cooling capacity and COP to be achieved. In terms of the exchanger dimensions, the optimum height of the channel was 5 mm while its length was in the range 1–2 m. Overall, the proposed irregular heat and mass exchanger could lead to significant enhanced energy performance compared to the existing flat-plate dew point cooling heat exchanger of the same geometrical dimensions. To achieve the same amount cooling output, the irregular heat and mass exchanger had the reduced size and cost against the flat-plate ones

Numerical analysis on magnetic leakage field of pipeline defect

Pipeline magnetic flux leakage inspection, mainly used for pipeline defect detection, is an important means of inner examination technology on pipeline. Flux leakage testing can't obtain valid defect identification signals by one hundred percent because of magnetization of the magnetic leakage field, the measured shape, size and location of pipeline defects, materials and operating conditions, and lift-off value, pole pitch and the length of steel brush during the measurement as well as forged pipe fittings such as welding seam, stiffener, flange and tee on the pipeline to be tested. This article reaches a conclusion that magnetic flux density distribution is influenced by the depth and width of defect through respectively researching magnetic leakage field of individual defect and double defects (thickness type) by finite-element method. It also conducts the numerical analysis on pipeline welding seam, stiffener, flange (increased wall thickness type) and tee (compound) leakage magnetic field in detection conditions of the same direction, and concludes their distribution rules of magnetic flux density. The characteristic parameters of distinguishing defect magnetic flux leakage field and the part of the pipeline magnetic flux leakage, derived from analysis and comparison of results on defective pipeline and conduit joint, stiffener, flange and tee magnetic flux leakage, provide a foundation of qualitative identification for accurately recognizing pipeline defect and eliminating the impact of other ancillary fittings on a pipe on pipeline magnetic flux leakage, and they can also offer infallible data to pipeline maintenance as a basis of quantitative analysis

Phosphorylation of Shox2 Is Required for Its Function to Control Sinoatrial Node Formation

Background: Inactivation of Shox2, a member of the short‐stature homeobox gene family, leads to defective development of multiple organs and embryonic lethality as a result of cardiovascular defects, including bradycardia and severe hypoplastic sinoatrial node (SAN) and sinus valves, in mice. It has been demonstrated that Shox2 regulates a genetic network through the repression of Nkx2.5 to maintain the fate of the SAN cells. However, the functional mechanism of Shox2 protein as a transcriptional repressor on Nkx2.5 expression remains completely unknown. Methods and Results: A specific interaction between the B56δ regulatory subunit of PP2A and Shox2a, the isoform that is expressed in the developing heart, was demonstrated by yeast 2‐hybrid screen and coimmunoprecipitation. Western blotting and immunohistochemical assays further confirmed the presence of phosphorylated Shox2a (p‐Shox2a) in cell culture as well as in the developing mouse and human SAN. Site‐directed mutagenesis and in vitro kinase assays identified Ser92 and Ser110 as true phosphorylation sites and substrates of extracellular signal‐regulated kinase 1 and 2. Despite that Shox2a and its phosphorylation mutants possessed similar transcriptional repressive activities in cell cultures when fused with Gal4 protein, the mutant forms exhibited a compromised repressive effect on the activity of the mouse Nkx2.5 promoter in cell cultures, indicating that phosphorylation is required for Shox2a to repress Nkx2.5 expression specifically. Transgenic expression of Shox2a, but not Shox2a‐S92AS110A, mutant in the developing heart resulted in down‐regulation of Nkx2.5 in wild‐type mice and rescued the SAN defects in the Shox2 mutant background. Last, we demonstrated that elimination of both phosphorylation sites on Shox2a did not alter its nuclear location and dimerization, but depleted its capability to bind to the consensus sequences within the Nkx2.5 promoter region. Conclusions: Our studies reveal that phosphorylation is essential for Shox2a to repress Nkx2.5 expression during SAN development and differentiation

Observation on the Curative Effect of Madopar Combined with Pramipexole in the Treatment of Parkinson’s Diseases

Parkinson’s disease is a common neurological degenerative disease in the elderly. The clinical manifestations are static tremor, increased muscle tone, slow movement, abnormal posture gait, and severe symptoms of loss of self-care. Parkinson’s disease has become a burden to not only patient, but also to his family and to the society. Normal human brain neurotransmitter dopamine and acetylcholine are in a balanced state, the two antagonism can maintain normal body function. The pathological changes of patients with Parkinson’s disease is degeneration and apoptosis of dopaminergic neurons in striatum, resulting in a significant reduction in dopamine levels, and thus lead to an imbalance in the effects of dopamine and acetylcholine, and a decrease in dopamine resistance to acetylcholine Parkinson’s disease symptoms. As such, this article will focus on the analysis of the Madopar and pramipexole in the treatment of Parkinson’s disease symptoms

Pest-YOLO: A model for large-scale multi-class dense and tiny pest detection and counting

Frequent outbreaks of agricultural pests can reduce crop production severely and restrict agricultural production. Therefore, automatic monitoring and precise recognition of crop pests have a high practical value in the process of agricultural planting. In recent years, pest recognition and detection have been rapidly improved with the development of deep learning-based methods. Although certain progress has been made in the research on pest detection and identification technology based on deep learning, there are still many problems in the production application in a field environment. This work presents a pest detector for multi-category dense and tiny pests named the Pest-YOLO. First, the idea of focal loss is introduced into the loss function using weight distribution to improve the attention of hard samples. In this way, the problems of hard samples arose from the uneven distribution of pest populations in a dataset and low discrimination features of small pests are relieved. Next, a non-Intersection over Union bounding box selection and suppression algorithm, the confluence strategy, is used. The confluence strategy can eliminate the errors and omissions of pest detection caused by occlusion, adhesion and unlabeling among tiny dense pest individuals to the greatest extent. The proposed Pest-YOLO model is verified on a large-scale pest image dataset, the Pest24, which includes more than 20k images with over 190k pests labeled by agricultural experts and categorized into 24 classes. Experimental results show that the Pest-YOLO can obtain 69.59% for mAP and 77.71% for mRecall on the 24-class pest dataset, which is 5.32% and 28.12% higher than the benchmark model YOLOv4. Meanwhile, our proposed model is superior to other several state-of-the-art methods, including the SSD, RetinaNet, Faster RCNN, YOLOv3, YOLOv4, YOLOv5s, YOLOv5m, YOLOX, DETR, TOOD, YOLOv3-W, and AF-RCNN detectors. The code of the proposed algorithm is available at: https://github.com/chr-secrect/Pest-YOLO