723 research outputs found

    Investigation of Application of Suction Line Heat Exchanger in R290 Air Conditioner with Small Diameter Copper Tube

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    R290 is a potential refrigerant replacing R22 because of its zero Ozone Depletion Potential (ODP) and virtually zero Global Warming Potential (GWP). However, R290 is flammable and requires excellent containment to avoid leakage and reduce the risk of fire. The use of small diameter copper tube (5 mm or even smaller) is an effective way to reduce refrigerant charge and thus reduce the risk of fire in the event of a refrigerant leak. However, employing small diameter copper tube will increase pressure drop and consequently reduce system performance. A suction line heat exchanger which employs the low temperature refrigerant in suction line to cool down the refrigerant before expansion value is a potential solution to improve system performance because R290 has low discharge temperature compared with HFC refrigerants (e.g. R22, R410A). This paper presents an investigation of application of a suction line heat exchanger in an R290 air conditioner with small diameter copper tube. A theoretical analysis is proposed at first to investigate the effect of the suction line heat exchanger on capacity and system energy efficiency under variable evaporating and cooling temperatures. A prototype R290 air conditioner with and without a suction line heat exchanger is tested in order to explore the effect of a suction line heat exchanger on system performance and refrigerant charge in real working conditions. Finally, a refrigerant circuit solution for heat pump air conditioners is proposed. The results of theoretical analysis indicate that the capacity and system energy efficiency increase linearly with the heat exchange of the suctionline heat exchanger, and the suction line heat exchanger can improves capacity by up to 12% and system energy efficiency by up to 4% under both cooling and heating modes. This is because the suction line heat exchanger increases the sub-cooling but has less impact on compressor power due to good thermal properties of R290. Further, the evaporating and condensation temperature have insignificant impact on the performance of suction line heat exchanger. The experimental results show that the suction line heat exchanger improves the cooling capacity and system efficiency by 5.3% and 4.5%, respectively. These results agree well with that of the system analysis. The sub-cooling temperature increases 10.2o C and the discharge temperature increases 25.4o C. Further, the suction line heat exchanger reduces the refrigerant charge by as much as 6%. This is because suction line heat exchanger increases the discharge temperature, and thus the superheat region of the condenser increases resulting in less refrigerant in the condenser. Overall, the use of a suction line heat exchanger in a system with small diameter copper tube improves the performance of R290 and more importantly reduces the refrigerant charge

    Deep Reinforcement Learning-based Multi-objective Path Planning on the Off-road Terrain Environment for Ground Vehicles

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    Due to the energy-consumption efficiency between up-slope and down-slope is hugely different, a path with the shortest length on a complex off-road terrain environment (2.5D map) is not always the path with the least energy consumption. For any energy-sensitive vehicles, realizing a good trade-off between distance and energy consumption on 2.5D path planning is significantly meaningful. In this paper, a deep reinforcement learning-based 2.5D multi-objective path planning method (DMOP) is proposed. The DMOP can efficiently find the desired path with three steps: (1) Transform the high-resolution 2.5D map into a small-size map. (2) Use a trained deep Q network (DQN) to find the desired path on the small-size map. (3) Build the planned path to the original high-resolution map using a path enhanced method. In addition, the imitation learning method and reward shaping theory are applied to train the DQN. The reward function is constructed with the information of terrain, distance, border. Simulation shows that the proposed method can finish the multi-objective 2.5D path planning task. Also, simulation proves that the method has powerful reasoning capability that enables it to perform arbitrary untrained planning tasks on the same map

    RESEARCH ON DATA MANAGEMENT MODEL OF NATIONAL DEFENSE MOBILIZATION POTENTIAL BASED ON GEO-SPATIAL FRAMEWORK

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    At present, the national defense mobilization potential data is mainly unstructured data composed of text, images, report forms, lacking space attribute and location information. Therefore, a large study of national defense mobilization potential database has focused on data collection, reporting and information system construction, etc. To solve national defense mobilization potential data application problems in the construction of informatization, taking advantage of the characteristics of geographical spatial framework, this paper discusses national defense mobilization potential data management model based on geographical spatial framework

    Study on the dynamic response characteristics of roadbed and pavement under the humidity and season factors in the hilly area of Southwest China

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    The environment of the roadbed and pavement often has a significant impact on its dynamic performance. The stability of the strata in the Hilly Area is poor, and long-term complex environmental impacts will cause significant damage to the pavement. This article tests the dynamic response characteristics of semi rigid and inverted asphalt pavement through road load tests, and measures the humidity data of the roadbed during on-site rainfall. In addition, the variation of pore water pressure in the transition layer under the coupling effect of humidity and dynamic load was analyzed, revealing the influence of seasonal factors on the dynamic response of the pavement and roadbed. The test results indicate that the humidity inside the roadbed is greatly influenced by seasonal factors, and the humidity conditions of the roadbed and pavement vary significantly due to differences in measurement point depth, season, and rainfall. Graded crushed stone cushion is beneficial for improving the humidity conditions of the roadbed. The pore water pressure of the graded crushed stone transition layer did not show significant pore water reabsorption throughout the entire loading process. Meanwhile, the thickness of the surface layer and the magnitude of the load have a significant impact on the measurement of pore water pressure in the transition layer. The measured values of the dynamic response indicators of the pavement are greatly influenced by seasonal factors. The research in this article will provide theoretical and guiding significance for the dynamic response characteristics of pavement under the influence of multiple factors in the southwestern hilly area

    Genome Editing of Pik3cd Impedes Abnormal Retinal Angiogenesis

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    Abnormal angiogenesis is associated with myriad human diseases including proliferative diabetic retinopathy. Signaling transduction via phosphoinositide 3-kinases (PI3Ks) plays a critical role in angiogenesis. Herein, we showed that p110δ, the catalytic subunit of PI3Kδ, was highly expressed in pathological retinal vascular endothelial cells (ECs) in a mouse model of oxygen-induced retinopathy (OIR) and in fibrovascular membranes from patients with proliferative diabetic retinopathy. To explore novel intervention with PI3Kδ expression, we developed a recombinant dual adeno-associated viral (rAAV) system for delivering CRISPR/Cas9 in which Streptococcus pyogenes (Sp) Cas9 expression was driven by an endothelial specific promoter of intercellular adhesion molecule 2 (pICAM2) to edit genomic Pik3cd, the gene encoding p110δ. We then demonstrated that infection of cultured mouse vascular endothelial cells with the dual rAAV1s of rAAV1-pICAM2-SpCas9 and rAAV1-SpGuide targeting genomic Pik3cd resulted in 80% DNA insertion/deletion in the locus of genomic Pik3cd and 70% depletion of p110δ expression. Furthermore, we showed that in the mouse model of OIR editing retinal Pik3cd with the dual rAAV1s resulted in not only a significant decrease in p110δ expression, and Akt activation, but also a dramatic reduction in pathological retinal angiogenesis. These findings reveal that Pik3cd editing is a novel approach to treating abnormal retinal angiogenesis

    Correction to: Genome Editing of Pik3cd Impedes Abnormal Retinal Angiogenesis, by Wu et al. Hum Gene Ther 2023;34(1-2):30-41; doi: 10.1089/hum.2022.079

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    In the January 2023 issue of Human Gene Therapy (vol. 34, no. 1-2; 30–41), the article titled Genome Editing of Pik3cd Impedes Abnormal Retinal Angiogenesis, by Wu et al. requires correction. The author byline originally appeared with the 13th author's name incorrectly published as GuomingZhao Wenyi Wu,1,2,3 Gaoen Ma,4 Hui Qi,5 Lijun Dong,5 Fang Chen,6 Yun Wang,5 Xingxing Mao,5 Xiaoqing Guo,2,3 Jing Cui,7 Joanne Aiko Matsubara,7 Bart Vanhaesebroeck,8 Xiaohe Yan,5Guoming Zhao,5 Shaochong Zhang,5,* and Hetian Lei 5,* The correct spelling of the author's name is GuomingZhang The online version of the article has been corrected to reflect this. The authors apologize for the error
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