Constant Circulation Research Articles

Contemporary Gifts: Solidarity, Compassion, Equality, Sacrifice, and Reciprocity from an NGO Perspective

This study explores how nongovernmental organizations (NGOs) at the recipient end of the foreign aid relationship perceive partnership and cooperation with donors. Empirical research in the West Bank and Gaza Strip has revealed that relations established by foreign aid resemble archaic gift exchange in the extent to which both foreign aid and gift exchange evoke concepts of solidarity, equality, reciprocity, and related power dynamics. The results of the research indicate that return-gifts exist even in financially unreciprocated foreign aid relations. Recipients return the “contemporary gifts” by providing a special material (documenting and sharing stories of suffering or poverty) to the donor, which leads to the constant circulation of the gift (“aid for pain” and “pain for aid,” to put it bluntly). The study draws attention to the complex social and political factors that local NGOs need to navigate to secure contemporary gifts, while it may also strengthen the validity of critical theories concerning...

Characterization of a Standardized Ex-vivo Porcine Model to Assess Short Term Intraocular Pressure Changes and Trabecular Meshwork Vitality After Pars Plana Vitrectomy with Different Silicone Oil and BSS Tamponades

ABSTRACTPurpose: The aim of this study was to characterize a standardized porcine ex-vivo testing system for intraocular pressure (IOP) monitoring after vitrectomy with different endotamponades.Methods: Twenty-four pig eyes, six per endotamponade group were obtained immediately postmortem. After pars plana vitrectomy, vitreous substitutes (silicone oil 1000 mPas, 2000 mPas, 5000 mPas, and Balanced Salt Solution (BSS)) were instillated and IOP was observed over 24-hours. Infusion pumps with Dulbecco’s Modified Eagle Medium (DMEM) simulated a constant aqueous humor circulation. A histological examination of the trabecular meshwork with DAPI- and TUNEL-staining was performed to detect the amount of apoptotic cells.Results: TUNEL-assay showed a mean cell death rate of 3.78% (SD ± 1.46%) for silicone oil endotamponades compared to 5.05% (SD ± 2.18%) in BSS group. One-way ANOVA (p = 0.425) showed no significant difference between both groups. Mean IOP in silicone oil endotamponades was 9.50 mmHg (SD ± 1.68 mmHg) at baseline, 13.23 mmHg (SD ± 0.79 mmHg) after 1 hour, 18.46 mmHg (SD ± 2.13 mmHg) after 12 hours and 15.51 mmHg (SD ± 2.82 mmHg) 24 hours after instillation. A comparison of all silicone oil groups (one-way ANOVA, Bonferroni post-hoc test, p = 0.269 to 1.000) didn’t reveal significant differences in mean IOP.Conclusion: The standardized ex-vivo porcine model represents an effective alternative to the in-vivo testing in animals. Maintaining the trabecular and uveoscleral outflow pathway enables a pseudo in-vivo analysis.

Experimental investigation of the impact and freezing processes of a water droplet on an ice surface

In the present study, we report for the first time the detailed dynamic motions of a water droplet impacting on an ice surface. Besides, the effects of the initial height of the water droplet and the ice surface temperature on the impact and freezing processes of the water droplet were experimentally investigated. During the experiment, an ice surface was generated first and then kept at a desired temperature by a constant temperature bath circulator. After that, a deionized water droplet was deposited onto the ice surface and its impact and freezing processes were recorded. The results showed that, during the impact process of the water droplet, once the water droplet reached its maximum contact diameter, the contact line of the water droplet was pinned on the ice surface without recoiling. Besides, at the same initial height of the water droplet, the decrease of the ice surface temperature resulted in the reduction of the maximum spreading factor and an apparent increase of the height of the ice bead. Moreover, once the droplet initial height was increased, the maximum spreading factor increased while the height of the ice bead reduced significantly.

Gypsy leadership, cohesion and social memory in the Evangelical Church of Philadelphia

Nowadays, although throughout Europe the Catholic, Orthodox, Muslim and Protestant denominational identities remain among Roma, the conversion rate would suggest the number of Roma Pentecostal will have numerically overtaken all the others in just a few years’ time. The uniqueness of Spanish Gypsy Pentecostalism contradicts some of the stereotypes of global Pentecostalism and resides in its organisational complexity and hierarchical structure, its rapid institutionalisation as a sole church, the thorough theological training of its leaders, and its autonomy both from the State and from the European and Latin American Pentecostal Roma Movement. This article is structured around a life history and two concerns: (a) the role of the constant circulation of the gypsy evangelical ministers as regards charisma and leadership; (b) the growing transfer of prestige from the respected gypsy elders to the young evangelical pastors and their role in wide pacification processes involving ethnic cohesion and kinship.

Fan Efficiency Improvement via Changing Guide Blade Shape Under Various Operating Conditions

The aim of this study is to examine the influence of sweep and tangential blade lean the guide vanes (GV) on the pressure losses in the blade row, and development of an approach to creating the GV with a rationally-shaped blades to ensure increased efficiency in the partial operating conditions. A numerical simulation method was used for research. As an object to be studied, was used an axial fan comprising an impeller and a GV, which were profiled to have constant circulation of velocity in radius. Verification of numerical simulation was based on the experimental data of fan. It comprised a GV with a straight blade and a circular-arc blade, with an impeller remained stationary in both cases. Among the turbulence models under consideration, preference is given to k-ω, as under operating conditions close to design ones, its result falls within the confidence span of the experimental characteristics, and at much higher and lower discharge coefficients a discrepancy is 4% at most. In addition to the characteristics, the fields of pressure losses in GV have been analyzed. Numerical modeling allowed us to have a well-reproduced structure of losses in the stationary blade row. Analysis of pressure loss fields has shown that in the original GV near the hub, on the blade back, under design conditions a flow breakdown takes off. In view of the research, was designed a new GV with a modified blade geometry. The GV blade axis near the hub was bent in the circumferential direction by 0.1 length of the blade. In the near-hub cross-sections the blade chord was increased by 10%. The results of numerical simulation have shown that, with the flow less than the designed one, a change of just the GV blade tip sections leads to reduced break-down zone near the hub by about 40% under both operating conditions without raising profile losses and to improved fan efficiency, which reduces fan drive power consumption under typical operating conditions in the propulsion system.

Control of Body Motion in an Ideal Fluid Using the Internal Mass and the Rotor in the Presence of Circulation Around the Body

In this paper, we study the controlled motion of an arbitrary two-dimensional body in an ideal fluid with a moving internal mass and an internal rotor in the presence of constant circulation around the body. We show that by changing the position of the internal mass and by rotating the rotor, the body can be made to move to a given point and discuss the influence of nonzero circulation on the motion control. We have found that in the presence of circulation around the body the system cannot be completely stabilized at an arbitrary point of space, but fairly simple controls can be constructed to ensure that the body moves near the given point.

A simplified model for heat extraction by circulating fluid through a closed-loop multiple-fracture enhanced geothermal system

Multiple hydraulic fractures have been proposed for improving the performance of an enhanced geothermal system (EGS) by providing conductive flow pathways and increased contact area between flowing fluid and surrounding rock formation. Use of more fractures incurs a higher drilling and hydraulic fracturing cost, but the additional cost can be offset by improved operation performance of an EGS. In this paper, a model is presented for efficiently predicting the output temperature so as to optimize the number of fractures and fracture spacing to maximize the EGS lifetime under a constant circulation rate. This optimal spacing is shown to arise due to the interplay among number of fractures, fracture spacing, well depth, and the pre-existing geothermal gradient. Specifically, under a typical geothermal gradient associated with EGS for a 5km total vertical depth of the well, the number of fractures N and the equal fracture spacing d have optimal values: 6⩽N⩽13 and 30m⩽d⩽90m. In addition, the semi-analytical solution method presented is effective and efficient in computation and, for this reason, is useful for optimizing the design of a geothermal reservoir with multiple layers at equal or non-equal spacing.

Momentum theory of Joukowsky actuator discs with swirl

Actuator disc theory is the basis for most rotor design methods, be it with many extensions and engineering rules added to make it a well-established method. However, the off-design condition of a very low rotational speed Ω of the disc is still a topic for scientific discussions. Several authors have presented solutions of the associated momentum theory for actuator discs with a constant circulation, the so-called Joukowsky discs, showing the efficiency Cp → ∞ for Ω → 0. The momentum balance is very sensitive to the choice of the vortex core radius δ as the pressure and velocity gradients become infinite for δ → 0. Viscous vortex cores do not show this singular behaviour so an inviscid core model is sought which removes the momentum balance sensitivity to singular flow. A vortex core with a constant δ does so. Applying this results in Cp → 0 for Ω → 0, instead of Cp → ∞. The Joukowsky actuator disc theory is confirmed by a very good match with the numerically obtained results. It gives higher Cp values than corresponding solutions for discs with a Goldstein-based wake circulation published in literature.

CO2/H2o High Temperature Co-Electrolysis Using LaFeO3-Based Oxide Cathode

An increasing awareness of severe environmental impact has been seriously concerned due to the increasing demand for energy, the diminishing resources of fossil fuels, and the tremendous effects on climate change. An important indication is from global warming effect, caused by effluent greenhouse gas emission (mainly CO2). Therefore, efficient management and utilisation of CO2 and energy (generation and storage) are required attention urgently. Co-electrolysis of steam and CO2in a solid state electrolysis cells (SOECs) is a promising strategy, which may provide an approach to not only effectively reduce climate impact, but also produce useful fuels (such as syngas and hydrocarbon source) through waste heat. Thus, this allows the conversion of electricity into a fuel, while giving new opportunities for efficient and effective use of energy. Ni-based cermet materials are usually used as fuel electrodes for SOECs, while constant circulation of reducing gas (H2 or CO) is required in order to prevent the oxidation of the metallic phase, which can lead to an issue of long-term operation. In addition, the stability of the conventional cathodes applied in electrolyser is still required to be much improved. Hence, decrease in degradation rate is essential for the application of high-temperature electrolyser. Therefore, utilisation of oxides as fuel electrodes has been highly suggested instead of metallic based electrodes. Previous our study has reported a promising LaFeO3-based perovskite material as a fuel electrode for CO2 electrolysis, showing a good activity and cell performance for CO2 reduction without carbon formation.[ 1 ] In this study, we further investigate co-electrolysis of CO2 and steam, using LSGM and LaFeO3-based materials for the electrolyte and cathode, respectively. Galvanostatic measurements and electrochemical impedance spectroscopy has been conducted to investigate the cell performance. A comparable current density of over ~0.61 A/cm2 has been achieved at ~1.6 V and 800°C. This study was focused on the formation of the syngas CO/H2 in operation. The content of the product gases was measured by gas chromatography installed with a thermal conductive detector. As Ni-based cermet is used as a cathode, a H2-enriched gas composition was formed particularly at < 800°C because of the dominant electrolysis of H2O and water-gas shift reaction (CO+H2O↔CO2+H2). However, in case of LaFeO3-based perovskite oxide cathode, a reasonable electrolysis current was achieved and the CO/H2 ratio in product was similar to the CO2/H2O in feeding composition. This suggests that LaFeO3-based oxide is active to CO2 electrolysis and presents low activity for water-gas shift reaction. Therefore, using LaFeO3-based oxide as a cathode of a co-electrolyser may be feasible for the control of CO/H2 ratio. [1] T. Ishihara, K.-T. Wu, S. Wang, ECS Trans. 2015, 66, 197.

Actuator line simulations of a Joukowsky and Tjæreborg rotor using spectral element and finite volume methods

The wake structure behind a wind turbine, generated by the spectral element code Nek5000, is compared with that from the finite volume code EllipSys3D. The wind turbine blades are modeled using the actuator line method. We conduct the comparison on two different setups. One is based on an idealized rotor approximation with constant circulation imposed along the blades corresponding to Glauert's optimal operating condition, and the other is the Tjffireborg wind turbine. The focus lies on analyzing the differences in the wake structures entailed by the different codes and corresponding setups. The comparisons show good agreement for the defining parameters of the wake such as the wake expansion, helix pitch and circulation of the helical vortices. Differences can be related to the lower numerical dissipation in Nek5000 and to the domain differences at the rotor center. At comparable resolution Nek5000 yields more accurate results. It is observed that in the spectral element method the helical vortices, both at the tip and root of the actuator lines, retain their initial swirl velocity distribution for a longer distance in the near wake. This results in a lower vortex core growth and larger maximum vorticity along the wake. Additionally, it is observed that the break down process of the spiral tip vortices is significantly different between the two methods, with vortex merging occurring immediately after the onset of instability in the finite volume code, while Nek5000 simulations exhibit a 2-3 radii period of vortex pairing before merging.

Performance analysis of wind turbines at low tip-speed ratio using the Betz-Goldstein model

Analyzing wind turbine performance at low tip-speed ratio is challenging due to the relatively high level of swirl in the wake. This work presents a new approach to wind turbine analysis including swirl for any tip-speed ratio. The methodology uses the induced velocity field from vortex theory in the general momentum theory, in the form of the turbine thrust and torque equations. Using the constant bound circulation model of Joukowsky, the swirl velocity becomes infinite on the wake centreline even at high tip-speed ratio. Rankine, Vatistas and Delery vortices were used to regularize the Joukowsky model near the centreline. The new formulation prevents the power coefficient from exceeding the Betz-Joukowsky limit. An alternative calculation, based on the varying circulation for Betz-Goldstein optimized rotors is shown to have the best general behavior. Prandtl’s approximation for the tip loss and a recent alternative were employed to account for the effects of a finite number of blades. The Betz-Goldstein model appears to be the only one resistant to vortex breakdown immediately behind the rotor for an infinite number of blades. Furthermore, the dependence of the induced velocity on radius in the Betz-Goldstein model allows the power coefficient to remain below Betz-Joukowsky limit which does not occur for the Joukowsky model at low tip-speed ratio.

Carbon capture test unit design and development using amine-based solid sorbent

This paper presents the design and development of a reactor system and the subsequent modifications to evaluate an integrated process to scrub carbon dioxide (CO2) from synthetic flue gas using amine based solid sorbents. The paper presents the initial system design and then discusses the various changes implemented to address the change in sorbent from a 180μm Geldart group B material to a 115μm Geldart group A material as well as issues discovered during experimental trials where the major obstacle in system operation was the ability to maintain a constant circulation of a solid sorbent stemming from this change in sorbent material.The system primarily consisted of four fluid beds, through which an amine impregnated solid sorbent was circulated and adsorption, pre-heat, regeneration, and cooling processes occurred. Instrumentation was assembled to characterize thermal, hydrodynamic, and gas adsorption performance in this integrated unit. A series of shakedown tests were performed and the configuration altered to meet the needs of the sorbent performance and achieve desired target capture efficiencies. Methods were identified, tested, and applied to continuously monitor critical operating parameters including solids circulation rate, adsorbed and desorbed CO2, solids inventories, and pressures.

Linear stability of Hill’s vortex to axisymmetric perturbations

We consider the linear stability of Hill’s vortex with respect to axisymmetric perturbations. Given that Hill’s vortex is a solution of a free-boundary problem, this stability analysis is performed by applying methods of shape differentiation to the contour dynamics formulation of the problem in a three-dimensional axisymmetric geometry. This approach allows us to systematically account for the effect of boundary deformations on the linearized evolution of the vortex under the constraint of constant circulation. The resulting singular integro-differential operator defined on the vortex boundary is discretized with a highly accurate spectral approach. This operator has two unstable and two stable eigenvalues complemented by a continuous spectrum of neutrally stable eigenvalues. By considering a family of suitably regularized (smoothed) eigenvalue problems solved with a range of numerical resolutions, we demonstrate that the corresponding eigenfunctions are in fact singular objects in the form of infinitely sharp peaks localized at the front and rear stagnation points. These findings thus refine the results of the classical analysis by Moffatt &amp; Moore (J. Fluid Mech., vol. 87, 1978, pp. 749–760).

MÉTODO PARA LA CRÍA EN LABORATORIO DE CHIRONOMIDAE (DIPTERA) DE AMBIENTES LÓTICOS

&lt;p&gt;La taxonomía de Chironomidae se apoya fuertemente en la integración de las características morfológicas de todas las fases del ciclo de vida, las cuales se pueden obtener mediante la cría en laboratorio. Este estudio desarrolló un método de cría en laboratorio de larvas de Chironomidae de ambientes lóticos. El método consta de una circulación constante de agua y distintos ítems alimenticios. Esta metodología ha permitido obtener asociaciones de los estados de larva, pupa y adulto para la identificación de especies presentes en una región de Argentina en la que el estado de conocimiento de la familia Chironomidae es incipiente.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Laboratory Rearing Methodology for Chironomidae (Diptera) of Lotic Environments&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;The taxonomy of Chironomidae is strongly supported by the integration of morphological characteristics of all stages of the life cycle, which can be obtained through laboratory rearing. This study was developed in laboratory to test rearing method for lotic Chironomidae larvae. The method included constant water circulation and different food items. This methodology allowed obtaining associations of larva, pupa and adult stages for the identification of species from an Argentinean region in which the knowledge of Chironomidae family is incipient.&lt;/p&gt;

Hepatitis E Virus SeroprevalencE among Different Age Groups of the Healthy Population of Kyrgyzstan

Knowledge regarding distribution of serological markers of Hepatitis E Virus (HEV) infection in the population of endemic regions is an important indicator of the public health and hygiene. The aim of this study was to determine seroprevalence of HEV among different age groups of the population in Kyrgyzstan regions. 648 serum samples of persons without liver pathology received in December 2014 to February 2015 was tested by immunoassay kit «DS-EIA-ANTI-HEV-G» (Diagnostic systems, Russia). IgG antibodies to HEV were detected in 4.8% (n = 31) of the examined samples. An analysis of the level of seropositivity in different regions and in different age groups of the population was made. The greatest number of seropositive persons were identified in Bishkek and Chuskaya oblast. The antibodies were detected most frequently in individuals aged 1 to 5, 15 to 19 years old and older than 50 years old. The obtained data indicate the constant virus circulation in Kyrgyzstan in interepidemic period.

Pengaruh Perbedaan Transportasi Sistem M-CLOVE dengan Konvensional dan Jenis Kelamin terhadap Respon Fisiologis Ayam Broiler

Meat consumption in Indonesia has increased with most needs come from broiler meat. However, it is not followed by development of the transportation technology that consider animal welfare. The purpose of this study was to compare the level of broiler stress measured from comb, shank and rectal temperature among sex between conventional transport system and environmentally transportation M- CLOVE. The results showed average of temperature and relative humidity during the transport process in the M-CLOVE was lower compared to the open crate. Temperature differences occured 1.4 °C with a relative humidity of 2.5% different. M-CLOVE transport reduced the level of stress of broiler which was indicated from lower comb temperature, shank temperature and rectal temperature which compared to broiler transported in open crate. Closed system and constant air circulation in the M-CLOVE might reduce the effects of heat generated from exposure to direct sunlight during the transportation process.

Free and controlled motion of a body with a moving internal mass through a fluid in the presence of circulation around the body

The free and controlled motion of an arbitrary two-dimensional body with a moving internal mass and constant circulation around the body in an ideal fluid is studied. Bifurcation analysis of the free motion is performed (under the condition of a fixed internal mass). It is shown that the body can be moved to a given point by varying the position of the internal mass. Some problems related to the presence of a nonzero drift of the body with a fixed internal mass are noted.

DID THE UNITED STATES SCARE THE EUROPEANS? THE PROPAGANDA ABOUT THE “AMERICAN DANGER” IN EUROPE AROUND 1900

During a brief period—1898 to 1907—the “American danger” proved a powerful slogan in Europe. Propaganda campaigns were launched that targeted the new ambitions of the emerging economic power. Historians have studied this episode but only as one among many examples of anti-Americanism embedded in European intellectual traditions. This paper insists on the distinctive character of this episode. It refutes the notion of anti-Americanism as the explanation most relevant to this episode and even questions the possibility of opposing Europe to the United States at a time of constant transnational circulation inside the “Atlantic world.” Disputing the idea that a common fear of American superiority united Europeans, the study reveals how people in England, France, and Germany used the “American danger” to put forward their own ideas of the national interest, which explains why the theme did not meet with the same success in each of these countries. Finally, the author offers the hypothesis that the “American danger” was less the expression of fear—as the Yellow Peril could be—and more a rallying cry for economic circles motivated by defense of their sectional interests and by a desire for national union in a time of deep political division.

On the Maximum of Wind Power Efficiency

In our paper we demonstrate that the filtration equation used by Gorban’ et al. for determining the maximum efficiency of plane propellers of about 30 percent for free fluids plays no role in describing the flows in the atmospheric boundary layer (ABL) because the ABL is mainly governed by turbulent motions. We also demonstrate that the stream tube model customarily applied to derive the Rankine-Froude theorem must be corrected in the sense of Glauert to provide an appropriate value for the axial velocity at the rotor area. Including this correction leads to the Betz-Joukowsky limit, the maximum efficiency of 59.3 percent. Thus, Gorban’ et al.’s 30% value may be valid in water, but it has to be discarded for the atmosphere. We also show that Joukowsky’s constant circulation model leads to values of the maximum efficiency which are higher than the Betz-Jow-kowsky limit if the tip speed ratio is very low. Some of these values, however, have to be rejected for physical reasons. Based on Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and S&oslashrensen we also illustrate that the maximum efficiency of propeller-type wind turbines depends on tip-speed ratio and the number of blades.

Comparison between DC Brushless Fan and DC Hybrid Solar Panel Cooling System

The purpose of this paper is compare between DC brushless fan and DC hybrid solar panel cooling system. The efficiency of PV module is depending on solar irradiance and ambient temperature. As temperature of PV module increase, the output current will increase but output voltage and output power will decrease and also vice versa. As solar irradiance increase, output current and output power will increase with linear and output voltage will increase with marginal and vice versa. The DC cooling system is a way to fix the issue of low efficiency of PV module with the intention to generate more electrical energy. To make an attempt to cool down the PV module, DC brushless fan and water pump with inlet/outlet manifold are built for constant fresh air movement and water flow circulation at the backside and front surface of PV module. The PV module with DC brushless fan cooling system increase 3.47 %, 29.55 %, 32.23 % in term of output voltage, output current, and output power respectively. It decrease 6.1 °C compare than to PV module without DC brushless fan cooling system. While PV module with DC hybrid cooling system increase 4.99 %, 39.90 %, 42.65 % in term of output voltage, output current, and output power respectively. It decrease 6.79 °C compare to PV module without DC hybrid cooling system. The efficiency of PV module with cooling system was increasing compared to PV module without cooling system, for the reason that the ambient temperature dropped significantly. An increase in efficiency of PV module, investment payback period of the system can reduce and the lifespan of PV module will be prolonged.