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Optimization Study of a Coanda Ejector

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Journal of Thermal Science 2006年第4期15卷 331-336页

作者： H.d.kim G.Rajesh T.Setoguchi S.Matsuo School of Mechanical Engineering Andong National University388Songcheon-dongAndongGyeongbuk 760-749Korea department of Mechanical Engineering Saga University1HonjoSaga 840-8502Japan

The Coanda effect has long been employed in the aerospace applications to improve the performances of various devices. This effect is the ability of a flow to follow a curved contour without separation and has well been utilized in ejectors where a high speed jet of fluid emerges from a nozzle in the ejector body, follows a curved surface and drags the secondary flow into the ejector. In Coanda ejectors, the secondary flow is dragged in the ejector due to the primary flow momentum. The transfer of momentum from the primary flow to the secondary flow takes place through turbulent mixing and viscous effects. The secondary flow is then dragged by turbulent shear force of the ejector while being mixed with the primary flow by the persistence of a large turbulent intensity throughout the ejector. The performance of a Coanda ejector is studied mainly based on how well it drags the secondary flow and the amount of mixing between the two flows at the ejector exit. The aim of the present study is to investigate the influence of various geometric parameters and pressure ratios on the Coanda ejector performance. The effect of various factors, such as, the pressure ratio, primary nozzle and ejector configurations on the system performance has been evaluated based on a performance parameter defined elsewhere. The performance of the Coanda ejector strongly depends on the primary nozzle configuration and the pressure ratio. The mixing layer growth plays a major role in optimizing the performance of the Coanda ejector as it decides the ratio of secondary mass flow rate to primary mass flow rate and the mixing length.

关键词： Coanda ejector compressible mixing layer flow dragging mixing length induced flow

dynamic behavior of stormwater quality parameters in South Texas

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Frontiers of Environmental Science & Engineering 2012年第6期6卷 825-830页

作者： Xubin PAN Jingyi ZHANG Wei-Ta FANG kim d.JONES Institute of Plant Quarantine Chinese Academy of Inspection and QuarantineBeijing 100029China department of Environmental Engineering Texas A&M University-KingsvilleKingsvilleTX 78363USA Graduate Institute of Environmental Education Taiwan Normal UniversityTaipei 116China

To control water impairment in urban storm- water, it is important to evaluate changing patterns of water quality parameters in stormwater runoff. Thus, the authors performed a series of experiments to investigate the dynamics of common water parameters during storm events in semi-arid areas, with multiple samples collected and analyzed in field stormwater applications. At this field monitoring site within McAuliffe Park, McAllen, Texas, in the United States, a storm event increased the concentra- tions of Escherichia coli （E. coli）, but this event represented a decreasing trend over the entire event period. Besides, peak intensity of different pollutants in the stormwater runoff occurred at different times other than at any peak flows, representing a complexity of the temporal and spatial measurements. Multi-sample per- event approaches recommended based on the complexity of the hydrograph and different peak intensity times of pollutants. In addition, high bacteria and total suspended solids （TSS） concentrations in the initial stage of the storm event should be considered when designing Best Manage- ment Practices （BMPs） and Low Impact developments （LIds）. New strategies and solutions for addressing ecohydrological challenges should be proposed to avoid collateral damages to their both common wealth in ecosystems and human well-beings.

关键词： event mean concentration first flush multi-sample per event ecohydrology

The significance of clinical practice guidelines on adult varicocele detection and management

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Asian Journal of Andrology 2016年第2期18卷 269-275,J0006,J0007页

作者： Anand Shridharani Ryan C Owen Osama O Elkelany Edward d kim department of Urology University of Tennessee College of Medicine Chattanooga TN 37403 USA division of Urology Department of Surgery University of Tennessee Graduate School of Medicine Knoxville TN 37920 USA.

Varicoceles are the most common correctable etiology of male factor infertility. However, the detection and management of varicoceles have not been standardized. This has led to decades of debate regarding the effect of varicocele on male infertility and subsequently whether repair leads to an improved fertility status. The current body of evidence investigating the role of varicocele and varicocelectomy is weak and conflicting. The stance taken by the AUA and ASRM suggests that there is insufficient outcomes data to support evidenced-based guidelines, citing evidence used to provide current recommendations are generally of a low quality level. On the other hand, the EAU Guidelines give a level la of evidence for management of varicoceles that are clinically palpable, associated with subnormal semen analyses and having otherwise unexplained fertility. Besides aiding with clinical varicocele detection and management, clinical practice opinion statements and guidelines aim to direct and strengthen the infrastructure of future studies. We review the current status of opinion statements and guidelines in varicocele and management detection with focus on their application in practice.

关键词： guidelines varicocele varicocele detection varicocele management varicocelectomy

Carbene-catalyzed activation of cyclopropylcarbaldehydes for mannich reaction andδ-lactam formation:remote enantioselecitvity control and dynamic kinetic asymmetric transformation

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Science China Chemistry 2021年第6期64卷 985-990页

作者： Jie Lv Jun Xu Xuling Pan Zhichao Jin Yonggui robin Chi State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering Key Laboratory of Green Pesticide and Agricultural BioengineeringMinistry of EducationGuizhou UniversityGuiyang 550025China School of Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China division of Chemistry&Biological Chemistry School of Physical&Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore

An N-heterocyclic carbene(NHC)-catalyzed enantioselective Mannich reaction of the remoteγ-carbon of cyclopropylcarbaldehydes is disclosed for the first ***-and enantiomerically enriched multicyclicδ-lactam compound is afforded as the main product from 8 possible stereo-specific isomers through dynamic kinetic asymmetric transformation(dYKAT)*** chiral functional molecules can be afforded from the lactam products through simple protocols with retentions of the optical purities.

关键词： N-heterocyclic carbene organocatalysis dynamic kinetic asymmetric transformation 1-cyclopropylcarbaldehydes asymmetric reactions

Riparian plant species differ in sensitivity to both the mean and variance in groundwater stores

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Journal of Plant Ecology 2020年第5期13卷 621-632页

作者： Kelly A.Steinberg kim d.Eichhorst Jennifer A.Rudgers department of Biology University of New MexicoAlbuquerqueNM 87131USA Bosque School Bosque Ecosystem Monitoring Program4000 Bosque School Road NWAlbuquerqueNM 87120USA

Aims determining the ecological consequences of interactions between slow changes in long-term climate means and amplified variability in climate is an important research frontier in plant *** combined the recent approach of climate sensitivity functions with a revised hydrological‘bucket model’to improve predictions on how plant species will respond to changes in the mean and variance of groundwater *** We leveraged spatiotemporal variation in long-term datasets of riparian vegetation cover and groundwater levels to build the first groundwater sensitivity functions for common plant species of dryland riparian *** results demonstrate the value of this approach to identifying which plant species will thrive(or fail)in an increasingly variable climate layered with declining groundwater *** Findings Riparian plant species differed in sensitivity to both the mean and variance in groundwater *** Grande cottonwood(Populus deltoides ***)cover was predicted to decline with greater inter-annual groundwater variance,while coyote willow(Salix exigua)and other native wetland species were predicted to benefit from greater year-to-year *** non-native species were sensitive to groundwater variance,but patterns for Russian olive(Elaeagnus angustifolia)predict declines under deeper mean groundwater *** air temperatures modulated groundwater sensitivity for cottonwood,which was more sensitive to variability in groundwater in years/sites with warmer maximum temperatures than in cool sites/*** cover declined most with greater intra-annual coefficients of variation(CV)in groundwater,but was not significantly correlated with inter-annual CV,perhaps due to the short time series(16 years)relative to cottonwood *** contrast,non-native tamarisk(Tamarix chinensis)cover increased with both intra-and inter-annual CV in ***,our results predict that changes in groundwater variab

关键词： climate change climate variability riparian Rio Grande New Mexico cottonwood willow tamarisk

Endovascular treatment of vasculogenic erectile dysfunction

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Asian Journal of Andrology 2015年第1期17卷 40-43,I0007页

作者： Edward d kim Ryan C Owen Gregory S White Osama O Elkelany Cyrus d Rahnema University of Tennessee Graduate School of Medicine Knoxville TN USA.

The treatment of erectile dysfunction （Ed） has been a fascination involving multiple medical specialities over the past century with urologic, cardiac and surgical experts all contributing knowledge toward this multifactorial disease. With the well-described association between Ed and cardiovascular disease, angiography has been utilized to identify vasculogenic impotence. Given the success of endovascular drug-eluting stent （dES） placement for the treatment of coronary artery disease, there has been interest in using this same technology for the treatment of vasculogenic Ed. For men with inflow stenosis, dES placement to bypass arterial lesions has recently been reported with a high technical success rate. Comparatively, endovascular embolization as an approach to correct veno-occlusive dysfunction has produced astonishing procedural success rates as well. However, after a thorough literature review, arterial intervention is only recommended for younger patients with isolated vascular injuries, typically from previous traumatic experiences. Short-term functional outcomes are less than optimal with long-term results yet to be determined. In conclusion, the hope for a minimally invasive approach to Ed persists but additional investigation is required prior to universal endorsement.

关键词： erectile dysfunction impotence penile erection vasculogenic

Enhanced thermoelectric performance of spark plasma sintered p-type Ca_(3-x)Y_(x)Co_(4)O_(9+δ)systems

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Journal of Materials Science & Technology 2020年第20期52卷 212-222页

作者： J.S.Cha d.H.kim H.Y.Hong K.Park Faculty of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul05006Republic of Korea

Highly textured dense Ca3-xYxCo4 O9+δ(0≤x≤0.3)samples were fabricated by combining sol-gel process with spark plasma sintering(SPS).Y^3+substitution for Ca^2+simultaneously increased the Seebeck coefficient and reduced the thermal *** latter was attributed to the increase in lattice anharmonicity,structural distortion,and grain boundary area,which enhanced the phonon ***2.7Y0.3Co4 O9+δshowed the largest dimensionless figure-of-merit(ZT=0.194)at 1073 K because it had the largest Seebeck coefficient and the lowest thermal *** ZT value was 55%larger than that of undoped Ca3 Co4 O9(0.125 at 1073 K).Therefore,Y^3+substitution,sol-gel powder synthesis,and SPS are highly effective for enhancing the thermoelectric prope rties of Ca_(3)Co_(4)O_(9).

关键词： Electrical conductivity Ca_(3)Co_(4)O_(9) Thermoelectric properties Seebeck coefficient Thermal conductivity Spark plasma sintering

Model-based adaptive locomotion and clustering control of microparticles through ultrasonic topological charge modulation

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Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 623-640页

作者： H.S.LEE H.X.CAO d.JUNG C.S.kim School of Mechanical Engineering Chonnam National UniversityGwangju 61186South Korea Korea Institute of Medical Microrobotics Gwangju 61011South Korea

We present a novel motion control technique for microrobot clusters to exploit the characteristics of the ultrasonic *** method comprises two steps,i.e.,introducing an ultrasonic actuation(UA)linear model for three-dimensional(3d)locomotion and controlling the topological charge(TC)in the ultrasonic vortex for microrobot ***,the TC is a controllable parameter for the expansion and contraction of the pressure null space inside the *** present a TC control method to cluster sporadically distributed microrobots in a specific *** validate the concept,a UA system composed of 30 ultrasonic transducers with 1 MHz frequency is fabricated,and the characteristics of the generated acoustic pressure field are analyzed through ***,the performances of the adaptive controller for precise 3d locomotion and the TC control method for clustering are ***,the UA technology,which performs both clustering and locomotion in a complex manner,is validated with a gelatin phantom in an in-vitro environment.

关键词： ultrasonic actuation(UA) topological charge(TC) adaptive control particle manipulation

Computational Analysis of the Compressible Flow driven by a Piston in a Ballistic Range

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Journal of Thermal Science 2007年第4期16卷 360-369页

作者： G.Rajesh R.Mishra H.G.Kang H.d.kim School of Mechanical Engineering Andong National University388Songcheon-DongAndong-760 749Korea

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics and aeroballistics, since it can create an extremely high-pressure state in very short time. Since the operation of the ballistic range includes many complicated phenomena, each process should be understood in detail for the performance enhancement of the device. One of the main processes which have significant influence on the device performance is the compression process of the driver gas. Most of the studies available in this field hardly discuss this phenomenon in detail and thus lack a proper understanding of its effect on the whole system performance. In the present study, a computational analysis has been made to investigate the fluid dynamic aspects of the compression process in the pump tube of a ballistic range and to assess how it affects the performance of the ballistic range. The results obtained are validated with the available experimental data. In order to evaluate the system performance, several performance parameters are defined. Effect of a shock tube added in between the pump tube and launch tube on the performance of the ballistic range is also studied analytically. Performance of the ballistic range could be significantly improved by the proper selection of the pump tube and high-pressure tube parameters and the addition of the shock tube.

关键词： Ballistic range compressible flow piston shock tube chimera mesh