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TAUBERIAN THEOREMS FOR WEAK ALMOST CONVERGENT FUNCTIONS

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Acta Mathematica Scientia 2011年第3期31卷 1203-1212页

作者： Meng-kuang kuo Center for General Education Jen- Teh Junior College of Medicine Nursing and Management NO 79-9 Sha-Luen Hu Xi-Zhou Li Hou-Loung Town Miaoli County Taiwan China

The almost convergent function which was introduced by Raimi [6] and discussed by Ho [4], Das and Nanda [2, 3], is the continuous analogue of almost convergent sequences （see [5]）. In this paper, we establish the Ta... 详细信息

关键词： almost convergent functions weak almost convergent functions Tauberian theorems Cauchy criterions

Optimization on bicriterion policies for M/G/1 system with second optional service

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1437-1445页

作者： Jau-chuan KE Yunn-kuang chu Department of Applied Statistics National Taichung Institute of Technology Taichung 404 Taiwan China

We compare the optimal operating cost of the two bicriterion policies, and , for an M/G/1 queueing system with second optional service, in which the length of the vacation period is randomly controlled either by the number of arrivals during the idle period or by a timer. After all the customers are served in the queue exhaustively, the server immediately takes a vacation and may operate policy or policy. For the two bicriterion policies, the total average cost function per unit time is developed to search the optimal stationary operating policies at a minimum cost. Based upon the optimal cost the explicit forms for joint optimum threshold values of (p,T) and (p,N) are obtained.

关键词： Average operating cost Bicriterion policy Optimization comparisons Optional service Optimal threshold values

Experimental and numerical study of tip injection in a subsonic axial flow compressor

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Chinese Journal of Aeronautics 2017年第3期30卷 907-917页

作者： Wei WANG Wuli chu Haoguang ZHANG Haiyang kuang School of Power and Energy Northwestern Polytechnical University Xi'an 710072 China Faculty of Water Resources and Hydroelectric Engineering Xi'an University of Technology Xi'an 710048 China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100083 China

Parametric study of tip injection was implemented experimentally on a subsonic axial flow compressor to understand the underlying flow mechanisms of stability improvement of the compressor with discrete tip *** throat height varied from 2 to 6 times the height of rotor tip clearance,and circumferential coverage percentage ranged from 8.3% to 25% of the *** pressure fluctuations over the rotor tip were measured with fast-response pressure ***-passage time-accurate simulations were also carried out to help us understand the flow *** combinations of tip injection with traditional casing treatments were experimentally studied to generate an engineering-acceptable method of compressor stall *** results indicate that the maximum stability improvement is achieved when injectors are choked despite their different *** effect of circumferential coverage percentage on compressor stability depends on the value of injector throat height for un-choked injectors,and vice *** blockage in the blade passage is greatly reduced by the choked injectors,which is the primary reason for stability *** accomplishment of blockage diminishment is maintained in the circumferential direction with the unsteady effect of tip injection,which manifests as a hysteresis between the recovery of tip blockage and the recovery of tip leakage *** unsteady effect is primarily responsible for the effectiveness of tip injection with a partial circumferential *** injection cannot enhance the stability of the rotor with axial slots significantly,but it can improve the stability of the rotor with circumferential grooves *** combined structure of tip injection with circumferential grooves is an alternative for engineering application.

关键词： Axial flow compressor Casing treatments Compressor stability Tip blockage Tip injection Tip leakage vortex

A combined application of micro-vortex generator and boundary layer suction in a high-load compressor cascade

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Chinese Journal of Aeronautics 2019年第5期32卷 1171-1183页

作者： Shan MA Wuli chu Haoguang ZHANG Xiangjun LI Haiyang kuang School of Power and Energy Northwestern Polytechnical University Collaborative Innovation Center of Advanced Aero-Engine

In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall.

关键词： Boundary layer suction Flow control strategies High-load compressor cascade Numerical simulations Vortex generators

Experimental investigation of nanoparticles precipitation in a rotating packed bed

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Particuology 2010年第4期8卷 372-378页

作者： Yang Xiang Guangwen chu Lixiong Wen kuang Yang Guangting Xiao Jianfeng Chen Key Laboratory for Nanomateriais Ministry of Education and Research Center of the Ministry of Education for High Gravity Engineering and Technology.Beijing University of Chemical Technology. Beijing 100029 China

Precipitation of BaSO4 nanoparticles was studied for the first time in a specially designed rotating packed bed （RPB）, which allowed sampling at different radial positions to provide better insight of the mechanism of precipitation in RPB. Particle size and morphology were characterized by TEM, while the quality of synthesized BaSO4 powders was analyzed by XRD and BET, and compared with those prepared in a stirred-tank reactor. The important role of the inlet region of the RPB in the whole precipitation process was experimentally confirmed, as a significant essence for the design of industrial RPB for the precipitation of sparingly soluble materials. The effects of different operating conditions on particle size were also investigated, showing that particle size decreases with increasing rotational speed and liquid flow rate, due to the enhancement of micromixing in the RPB.

关键词： Rotating packing bed BaSO4 Nanoparticle Precipitation Mixing

Tidal Asymmetry Changes in a Shallow Mud Estuary by a Restoration Project

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Journal of Ocean University of China 2019年第2期18卷 339-348页

作者： LIANG Huidi kuang Cuiping GU Jie MA Yue CHEN kuo LIU Xu College of Civil Engineering Tongji University College of Marine Ecology and Environment Shanghai Ocean University

The tidal asymmetry-induced siltation below tidal barriers is a worldwide problem that restricts regional socio-economic and environmental development. The hydrodynamic processes of the small mud estuary also feature a high uncertainty after estuary restoration measures. In this study, a hydrodynamic model based on the MIKE21 is used to quantify the responses of tidal asymmetry to a two-phase restoration project in Shuanglong Estuary, Bohai Bay, China. According to the numerical modeling results, the tidal flat removal in the upper estuary(first-phase restoration) induces the flood asymmetry switching to the ebb asymmetry in unrestored reach but enhances flood asymmetry in widening restored reach. Although the tidal asymmetry reverts to flood-dominated pattern after full restoration over the estuary, the imbalance between flood and ebb velocities is relieved. A possible net sediment transport pattern based on a comparison of dominant asymmetric current and actual sediment transport period shows net sediments in the upper estuary and inlet transport seaward and landward, respectively, in the first-phase restoration, whereas landward net sediment transport occurs in the whole estuary under the second-phase restoration scenario. Given these results, we assume that a switch from the flood-dominated estuary to ebb-dominated estuary can be caused by redesigning the cross-sectional profile. The quantitative comparison of Lagrangian residual currents also implies that a channel–shoal structure rather than a flat bathymetry can promote the mass transport. Therefore, reshaping the channel–tidal flat system in restoration projects can prevent the sedimentation of the estuary and improve the water environment.

关键词： tidal asymmetry restoration project mud estuary net sediment transport

Numerical simulation of flow hydrodynamics of struvite pellets in a liquid–solid fluidized bed

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Journal of Environmental Sciences 2017年第7期29卷 391-401页

作者： Xin Ye Dongyuan chu Yaoyin Lou Zhi-Long Ye Ming kuang Wang Shaohua Chen Key Laboratory of Urban Pollutant Conversion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China College of the Environment and Ecology Xiamen UniversityXiamen 361102China Fujian Academic of Agricultural Sciences Fuzhou 350003China

Phosphorus recovery in the form of struvite has been aroused in recent decades for its dual advantages in eutrophication control and resource *** usage of the struvite products is normally determined by the size which is largely depended on the *** this study,flow behavior of struvite pellets was simulated by means of Eulerian–Eulerian two-fluid model combining with kinetic theory of granular flow in a liquid–solid fluidized bed reactor（FBR）.A parametric study including the mesh size,time step,discretization strategy,turbulent model and drag model was first developed,followed by the evaluations of crucial operational conditions,particle characteristics and reactor *** results showed that a cold model with the mesh resolution of 16 × 240,default time step of 0.001 sec and first order discretization scheme was accurate enough to describe the *** struvite holdup profile using Syamlal–O＇Brien drag model was best fitted to the experimental data as compared with other drag models and the empirical Richardson–Zaki *** the model evaluation,it showed that liquid velocity and particle size played important roles on both solid holdups and *** reactor diameter only influenced the solid velocity while the static bed height almost took no *** results are direct and can be applied to guide the operation and process control of the struvite ***,the model parameters can also be used as the basic settings in further crystallization simulations.

关键词： Numerical simulation Flow hydrodynamics Struvite Liquid–solid fluidized bed

User-guided line abstraction using coherence and structure analysis

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Computational Visual Media 2017年第2期3卷 177-188页

作者： Hui-Chi Tsai Ya-Hsuan Lee Ruen-Rone Lee Hung-kuo chu Department of Computer Science "National Tsing Hua University" Information and Communications Research Laboratories Industrial Technology Research Institute

Line drawing is a style of image abstraction where the perceptual content of the image is conveyed using distinct straight or curved lines. However,extracting semantically salient lines is not trivial and mastered only by skilled artists. While many parametric filters have successfully extracted accurate and coherent lines, their results are sensitive to parameter choice and easily lead to either an excessive or insufficient number of lines. In this work, we present an interactive system to generate concise line abstractions of arbitrary images via a few user specified strokes. Specifically, the user simply has to provide a few intuitive strokes on the input images, including tracing roughly along edges and scribbling on the region of interest, through a sketching interface. The system then automatically extracts lines that are long,coherent and share similar textural structures to form a corresponding highly detailed line drawing. We have tested our system with a wide variety of images. Our experimental results show that our system outperforms state-of-the-art techniques in terms of quality and efficiency.

关键词： line abstraction interactive drawing coherence strokes structure strokes stroke matching

Nomogram to predict permanent stoma in rectal cancer patients after sphincter-saving surgery

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World Journal of Gastrointestinal Surgery 2022年第8期14卷 765-777页

作者： Chih-Yu kuo Po-Li Wei Chia-Che Chen Yen-kuang Lin Li-Jen kuo Department of Surgery Taipei Medical University HospitalTaipei 11031Taiwan Division of Colorectal Surgery Department of SurgeryTaipei Medical University HospitalTaipei 11031Taiwan Department of Surgery School of MedicineCollege of MedicineTaipei Medical UniversityTaipei 11031Taiwan Graduate Institute of Athletics and Coaching Science National Taiwan Sport UniversityTaoyuan 33301Taiwan Taipei Cancer Center Taipei Medical UniversityTaipei 11031Taiwan

BACKGROUND Approximately 20 percent of patients with a tumour localized in the low rectum still encounter the possibility of requiring permanent stoma(PS), which can cause drastic changes in lifestyle and physical *** To determine the risk factors for PS and to develop a prediction model to predict the probability of PS in rectal cancer patients after sphincter-saving *** A retrospective cohort of 421 rectal cancer patients who underwent radical surgery at Taipei Medical University Hospital between January 2012 and December 2020 was included in this study. Univariate and multivariate analyses were performed to identify the independent risk factors for PS. A nomogram was developed according to the independent risk factors obtained in the multivariate analysis. The performance of the nomogram was assessed using a receiver operating characteristic curve and a calibration *** The PS rate after sphincter-saving surgery was 15.1%(59/391) in our study after a median follow-up of 47.3 mo(range 7–114 mo). Multivariate logistic regression analysis demonstrated that local recurrence, perirectal abscess, anastomosis site stenosis, perineural invasion, tumor size and operative time were independent risk factors for PS. These identified risk factors were incorporated into the nomogram, and the concordance index of this model was 0.903(95%CI: 0.851-0.955). According to the calibration curves, the nomogram represents a perfect prediction *** Several risk factors for PS after sphincter-saving surgery were identified. Our nomogram exhibited perfect predictive ability and will improve a physician’s ability to communicate the benefits and risks of various treatment options in shared decision making.

关键词： Nomogram Permanent stoma Risk factor Shared decision making Sphincter-saving operation Rectal cancer