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Experimental Study on Performance of a closed Wet Cooling Tower for Air Wet-Bulb Temperature near 0°C

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Journal of Thermal Science 2019年第5期28卷 1015-1023页

作者： ZHOU Yasu ZHANG Pan ZHAO Jingde YANG Honghai BAI Yufeng College of Environmental Science and Engineering Donghua University

closed wet cooling towers(CWCTs) are used widely because of their better water quality and smaller water consumption. However, the operating parameters shown in the technical documents are only for rated conditions in summer, not for any other conditions, especially in low air wet-bulb temperature areas such as those near 0℃. In addition, CWCTs often fail to achieve the designed cooling effect at low air wet-bulb temperatures. A experiment set of CWCT was built, and the performance of the CWCT at low air wet-bulb temperature near 0℃ was investigated. The impact of the operating parameters(air flow rate, cooling water flow rate, and spray water flow rate) on the heat and mass transfer performance of the CWCT was measured and analyzed. The results show the cooling performance of the CWCT at an air wet-bulb temperature 0℃, 2℃, and 4℃ is about 47%–63% of the rated operating condition;the optimal operating parameters of these conditions for the CWCT are just the same as those of the rated operating condition in summer. According to the experimental results, some operating advices are given.

关键词： closed wet cooling tower performance of cooling tower low air wet-bulb temperature rated operating parameters evaluation index

Influence of Filling Ratio and Working Fluid Thermal Properties on Starting up and Heat Transferring Performance of closed Loop Plate Oscillating Heat Pipe with Parallel Channels

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Journal of Thermal Science 2017年第1期26卷 73-81页

作者： SHI Weixiu PAN Lisheng School of Environment and Energy Engineering Beijing University of Civil Engineering and Architecture Beijing Key Lab of Heating Gas SupplyVentilating and Air Conditioning Engineering State Key Laboratory of High-temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences

Using ethanol or acetone as the working fluid, the performance of starting up and heat transfer of closed-loop plate oscillating heat pipe with parallel channels(POHP-PC) were experimentally investigated by varying filling ratio, inclination, working fluids and heating power. The performance of the tested pulsating heat pipe was mainly evaluated by thermal resistance and wall temperature. Heating copper block and cold water bath were adopted in the experimental investigations. It was found that oscillating heat pipe with filling ratio of 50% started up earlier than that with 70% when heating input was 159.4 W, however, it has similar starting up performance with filling ratio of 50% as compared to 70% on the condition of heat input of 205.4 W. And heat pipe with filling ratio of 10% could not start up but directly transit to dry burning. A reasonable filling ratio range of 35%-70% was needed in order to achieve better performance, and there are different optimal filling ratios with different heating inputs- the more heating input, the higher optimal filling ratio, and vice versa. However, the dry burning appeared easily with low filling ratio, especially at very low filling ratio, such as 10%. And higher filling ratio, such as 70%, resulted in higher heat transfer( dry burning) limit. With filling ratio of 70% and inclination of 75°, oscillating heat pipe with acetone started up with heating input of just 24 W, but for ethanol, it needed to be achieved 68 W, Furthermore, the start time with acetone was similar as compared to that with ethanol. For steady operating state, the heating input with acetone was about 80 W, but it transited to dry burning state when heating input was greater than 160 W. However, for ethanol, the heating input was in vicinity of 160 W. Furthermore, thermal resistance with acetone was lower than that with ethanol at the same heating input of 120 W.

关键词： closed loop with parallel channels, plate pulsating heat pipe, filling ratio, working fluid thermalproperties, start up, heat transfer performance

closed characteristics on non-degenerate star-shaped hypersurfaces in R^(2n)

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Science China Mathematics 2002年第8期45卷 1038-1052页

作者：胡锡俊龙以明 1. Nankai Institute of Mathematics Nankai University 300071 Tianjin China

In this paper, firstly we establish the relation theorem between the Maslov-type index and the index defined by C. Viterbo for star-shaped Hamiltonian systems. Then we extend the iteration formula of C. Viterbo for non-degenerate star-shaped Hamiltonian systems to the general case. Finally we prove that there exist at least two geometrically distinct closed characteristics on any non-degenerate star-shaped compact smooth hypersurface on R2n with n ＞ 1. Here we call a hypersurface non-degenerate, if all the closed characteristics on the given hypersurface together with all of their iterations are non-degenerate as periodic solutions of the corresponding Hamiltonian system. We also study the ellipticity of closed characteristics when n=2.

关键词： Maslov-type index, iteration theory, star-shaped hypersurface, closed characteristics, non-degeneracy.

CONDENSING HEAT TRANSFER IN AN ADVANCED TWO-PHASE closed THERMOSYPHON

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Chinese Journal of Chemical Engineering 1996年第1期4卷 88-92页

作者：李修伦闻建平单岩昆黄鸿鼎天津大学化学工程系天津

1 INTRODUCTIONclosed thermosyphon has been developed to enhance heat transfer and recover wasteheat in various process industries [1,2].Stimulated by this success,a new type oftwo-phase closed thermosyphon was designed by inserting respectively two inner tubesinto the thermosyphon,one in the boiling section and the other in the condensing *** two-phase flow boiling heat transfer coefficient was calculated successfully onthe basis of Chen’s dual-mechanism [3].A boiling heat transfer model for thetwo-phase closed thermosyphon with an inner tube in the boiling section was pro-

关键词： two-phase closed thermosyphon heat transfer narrow annulus

CLS-Miner: efficient and effective closed high-utility itemset mining

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Frontiers of Computer Science 2019年第2期13卷 357-381页

作者： Thu-Lan DAM Kenli LI Philippe FOURNIER-VIGER Quang-Huy DUONG College of Computer Science and Electronic Engineering Hunan University Changsha 410082 China Faculty of Information Technology Hanoi University of Industry Hanoi Vietnam CIC of HPC National University of Defense Technology Changsha 410073 China National Supercomputing Center in Changsha Changsha 410082 China School of Natural Sciences and Humanities Harbin Institute of Technology Shenzhen Graduate School Shenzhen 518055 China Department of Computer Science Norwegian University of Science and Technology Trondheim Norway

High-utility itemset mining (HUIM) is a popular data mining task with applications in numerous domains. However, traditional HUIM algorithms often produce a very large set of high-utility itemsets (HUIs). As a result, analyzing HUIs can be very time consuming for users. Moreover, a large set of HUIs also makes HUIM algorithms less efficient in terms of execution time and memory consumption. To address this problem, closed high-utility itemsets (CHUIs), concise and lossless representations of all HUIs, were proposed recently. Although mining CHUIs is useful and desirable, it remains a computationally expensive task. This is because current algorithms often generate a huge number of candidate itemsets and are unable to prune the search space effectively. In this paper, we address these issues by proposing a novel algorithm called CLS-Miner. The proposed algorithm utilizes the utility-list structure to directly compute the utilities of itemsets without producing candidates. It also introduces three novel strategies to reduce the search space, namely chain-estimated utility co-occurrence pruning, lower branch pruning, and pruning by coverage. Moreover, an effective method for checking whether an itemset is a subset of another itemset is introduced to further reduce the time required for discovering CHUIs. To evaluate the performance of the proposed algorithm and its novel strategies, extensive experiments have been conducted on six benchmark datasets having various characteristics. Results show that the proposed strategies are highly efficient and effective, that the proposed CLS-Miner algorithm outperforms the current state-ofthe- art CHUD and CHUI-Miner algorithms, and that CLSMiner scales linearly.

关键词： utility mining high-utility itemset mining closed itemset mining closed high-utility itemset mining

Enhancement effect of cumulative second-harmonic generation by closed propagation feature of circumferential guided waves

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Chinese Physics B 2020年第2期29卷 301-308页

作者： Guang-Jian Gao Ming-Xi Deng Ning Hu Yan-Xun Xiang Department of Physics Army Logistics UniversityChongqing 401331China College of Aerospace Engineering Chongqing UniversityChongqing 400044China School of Mechanical and Power Engineering East China University of Science and TechnologyShanghai 200237China

On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of *** appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the *** a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode *** theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic *** applications of the enhancement effect of cumulative SHG of CGWs are considered and *** theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube.

关键词： circumferential guided wave second-harmonic generation(SHG) enhancement effect of cumulative SHG closed propagation feature

Weakly closed Graphs and F-Purity of Binomial Edge Ideals

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Algebra Colloquium 2018年第4期25卷 567-578页

作者： Kazunori Matsuda Kitami Institute of Technology Kitami

Herzog,Hibi,Hreinddttir et *** the class of closed graphs,and they proved that the binomial edge ideal JG of a graph G has quadratic GrSbner bases if G is *** this paper,we introduce the class of weakly closed graphs as a generalization of the closed graph,and we prove that the quotient ring S/JG of the polynomial ring S=K[x1,...,xn,y1,...,yn]with K a field and n=|V(G)|is F-pure if G is weakly *** fact is a generalization of Ohtani's theorem.

关键词： binomial edge ideal closed graph weakly closed graph F-pure

Changes in neurological and pathological outcomes in a modified rat spinal cord injury model with closed canal

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Neural Regeneration Research 2020年第4期15卷 697-704页

作者： Xin Sun Xing-Zhen Liu Jia Wang Hai-Rong Tao Tong Zhu Wen-Jie Jin Kang-Ping Shen Shanghai Key Laboratory of Orthopedic Implants Department of Orthopedic SurgeryShanghai Ninth People’s HospitalShanghai Jiao Tong University School of MedicineShanghaiChina Department of Pathology Shanghai Xinhua HospitalShanghai Jiao Tong University School of MedicineShanghaiChina

Most animal spinal cord injury models involve a laminectomy,such as the weight drop model or the transection ***,in clinical practice,many patients undergo spinal cord injury while maintaining a relatively complete spinal ***,open spinal cord injury models often do not simulate real injuries,and few previous studies have investigated whether having a closed spinal canal after a primary spinal cord injury may influence secondary ***,we aimed to assess the differences in neurological dysfunction and pathological changes between rat spinal cord injury models with closed and open spinal ***-Dawley rats were randomly divided into three *** the sham group,the tunnel was expanded only,without inserting a screw into the spinal *** the spinal cord injury with open canal group,a screw was inserted into the spinal canal to cause spinal cord injury for 5 minutes,and then the screw was pulled out,leaving a hole in the vertebral *** the spinal cord injury with closed canal group,after inserting a screw into the spinal canal for 5 minutes,the screw was pulled out by approximately 1.5 mm and the flat end of the screw remained in the hole in the vertebral plate so that the spinal canal remained closed;this group was the modified model,which used a screw both to compress the spinal cord and to seal the spinal *** 7 days post-operation,the Basso-Beattie-Bresnahan scale was used to measure changes in neurological ***-eosin staining was used to assess *** evaluate the degree of local secondary hypoxia,immunohistochemical staining and western blot assays were applied to detect the expression of hypoxia-inducible factor 1α(HIF-1α)and vascular endothelial growth factor(VEGF).Compared with the spinal cord injury with open canal group,in the closed canal group the Basso-Beattie-Bresnahan scores were lower,cell morphology was more irregular,the percentage of morphologically normal neurons was lower

关键词： Basso-Beattie-Bresnahan scores closed spinal canal HIF-1α hypoxia model nerve regeneration open spinal canal rat secondary injury spinal cord injury VEGF

On the Cegrell Classes Associated to a Positive closed Current

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Chinese Annals of Mathematics,Series B 2019年第4期40卷 567-584页

作者： Mohamed ZAWAY Department of Mathematics Faculty of Sciences Ad DwadimiShaqra University Department of Mathematics Faculty of Science of Gabes University of Gabes

The aim of this paper is to study the operatoron■ on some classes of plurisubharmonic (psh) functions, which are not necessary bounded, where T is a positive closed current of bidimension (q, q) on an open set ? of C^n. The author introduces two classes F_p^T (?) and■ and shows first that they belong to the domain of definition of the operator■. Then the author proves that all functions that belong to these classes are C_T-quasi-continuous and that the comparison principle is valid for them.

关键词： Positive closed current Plurisubharmonic function Capacity Monge-Ampère Operator