Meandering Path Research Articles

VOF-DEM study of particle entrainment behaviors in the gas–solid-liquid system with multi-inlet configuration

Enhancing the entrainment capability of particles by bubbles is pivotal for facilitating particle elutriation and augmenting reaction efficiency in gas–liquid-solid systems. The current work utilizes the volume of fluid method in conjunction with discrete element method (VOF-DEM) to study particle entrainment in gas–liquid-solid three-phase reactors featuring different gas inlet layouts. Following model validation, this study delves into the multiphase flow characteristics and particle behaviors in detail. The results reveal that the merging of adjacent channels leads to the formation of larger combined bubbles, thereby increasing particle force, velocity and entrainment height. The average entrainment height during the merging of adjacent bubble channels is 42% higher compared to the four-channel configuration. However, this amalgamation diminishes the channel count and particle entrainment count. Specifically, the highest particle entrainment occurs in the two-channel configuration, which is 26% greater than that in the adjacent-channel merging configuration. Conversely, increasing the channel number decreases bubble size and overall particle entrainment capacity. With consistent bubble sizes, an increase in particle entrainment is associated with reduced entrainment height, indicative of diminished momentum transfer from bubble wakes to individual particles. Additionally, maintaining an optimal number of channels ensures high gas inlet velocity and bubble size, thereby enhancing particle entrainment efficiency. Lastly, appropriately reducing channel distance fosters interaction between adjacent channels, resulting in a meandering bubble path that further promotes particle entrainment and elution efficiency. The results obtained from this study serve as a useful reference for the design and optimization of similar systems.

Bed shear stress distribution across a meander path

ABSTRACT Laboratory experimentation for bed shear stress distribution has been carried out in two sets of meandering channels. The channels have crossover angles of 110° and 60° constructed by ‘sine-generated’ curves over a flume of 4 m width. Variations in bed roughness were studied for the meandering main channel. Bed shear stress distribution across a meandering length for the 110° and 60° channels was examined for different sinuosities and roughnesses. The boundary shear stress study illustrated the position of maximum shear along the apex section and across the meandering path. These variations were observed for different flow depths. A comparison of the bed shear among the three experimental channels was conducted, and the results were analyzed.

Deep Winter Mixed Layer Anchored by the Meandering Antarctic Circumpolar Current: Cross-Basin Variations

Abstract A deep winter mixed layer forms north of the Antarctic Circumpolar Current (ACC) in the Indo-Pacific sectors, while the mixed layer depth (MLD) is shallow in the Atlantic. Using observations and a global atmospheric model, this study investigates the contribution of surface buoyancy flux and background stratification to interbasin MLD variations. The surface heat flux is decomposed into broad-scale and frontal-scale variations. At the broad scale, the meandering ACC path is accompanied by a zonal wavenumber-1 structure of sea surface temperature (SST) with a warmer Pacific than the Atlantic; under the prevailing westerly winds, this temperature contrast results in larger surface heat loss facilitating deeper MLD in the Indo-Pacific sectors than in the Atlantic. In the Indian sector, the intense ACC fronts strengthen surface heat loss compared to the Pacific. The surface freshwater flux pattern largely follows that of evaporation and reinforces the heat flux pattern, especially in the southeast Pacific. A diagnostic relationship is introduced to highlight the role of ACC’s sloping isopycnals in setting a weak submixed layer stratification north of ACC. This weak stratification varies in magnitude across basins. In the Atlantic and western Indian Oceans where the ACC is at a low latitude (∼45°S), solar heating, intrusions of subtropical gyres, and energetic mesoscale eddies together maintain relatively strong stratification. In the southeast Pacific, in comparison, the ACC reaches the southernmost latitude (56°S), far away from the subtropical front. This creates weaker stratification, allowing deep mixed layers to form, aided by surface buoyancy loss.

Global path planning for autonomous construction vehicles in building construction: A comparative study with a focus on vehicle kinematic characteristics

Technological advancements in robotics and automation have led to a growing emphasis on integration into construction industry from a global research context. In particular, autonomous construction vehicles (ACVs) stand out as a pivotal innovation. One key aspect of successful deployment of ACVs on construction sites is the path planning technology, especially the global path planning (GPP) methods. Thus, this study conducted a comparative study of the six GPP algorithms from various underlying principles, including graph search methods (e.g. Dijkstra and A*), sampling-based methods (e.g. rapidly exploring random tree (RRT) and rapidly exploring random tree star (RRT*)), evolutionary computation (e.g. genetic algorithms (GAs)), and artificial intelligence (e.g. deep Q learning (DQN)), to reveal how GPP algorithms perform on the travel of ACVs. These algorithms were evaluated with consideration of the kinematic characteristics of typical construction vehicles, including truck-trailers and excavators, within a typical unstructured real-world building construction site and based on two tasks and eight criteria encompassing efficiency and safety. The findings were analysed from three perspectives, i.e. the planned global paths and travel paths of ACVs, the performance of algorithms in each metric, and the overall performance of each algorithm, to identify the strengths of each GPP algorithm. GAs excel in generating smoother travel paths than others, whereas the global paths from RRT and DQN exhibit unpredictable changes, leading to a meandering travel paths for ACVs. The quality of global paths induces a greater impact on differential-wheeled excavators compared to front-wheel steering truck-trailers. Practical guidance can therefore be provided to select and improve the GPP algorithms and thereby to enhance the safety and efficiency of ACVs on construction sites.

Influence of wake meandering path on floater motions

This study shows how different versions of the dynamic wake meandering (DWM) model will result in different dynamic behaviour of a floating wind turbine. In this study, different softwares as well as different input wind boxes are applied. The effect of these variations were studied using statistics from both the meandering behaviour of the wake and the response of a floating wind turbine. The yaw response is the most sensitive, and this study shows that the standard deviation of the yaw response is between 10% to 60%, depending on the DWM options used when generating the wake wind field.

Experimental investigation of three-dimensional flow dynamics in a laboratory-scale meandering channel under subcritical flow condition

This study investigates the three-dimensional turbulence flow properties in a meandering channel under subcritical flow conditions, specifically focusing on a few critical parameters such as three-dimensional velocity behaviour, Turbulent kinetic energy, skewness, and kurtosis. A model study has been attempted by considering the same sinuosity, Froude number, and bed material from an Indian peninsular river to understand the basic hydrodynamics of a meandering channel. Understanding these critical parameters is crucial for comprehending the complex flow behaviour and its implications in meandering channels. Experimental measurements were conducted to collect data on Velocity, Turbulent Kinetic energy, skewness, and kurtosis in all three directions. The objective was to analyse their variations and behaviour along the meandering path, providing insights into the flow dynamics and turbulence characteristics. Advanced measurement techniques, such as Acoustic Doppler Velocimeters (ADV), were utilized to obtain accurate and detailed data. The study revealed distinct patterns and trends in the velocity, Turbulent Kinetic energy, skewness, and kurtosis along the flow path of a sand bed meandering channel. These parameters were found to vary significantly in different sections, highlighting the influence of channel geometry and flow conditions. Graphical representations of the flow profiles were employed to visualize the spatial distribution and understand the variations in these turbulence properties. The findings of this study enhance our understanding of the three-dimensional turbulence flow properties in sand bed meandering channels under subcritical flow conditions. The results offer valuable information for designing hydraulic structures, flood control measures, and river restoration projects.

Impact of the Kuroshio large meander on local atmospheric circulation and precipitation in winter

The Kuroshio, which flows to the south of Japan, typically takes two paths on decadal timescales; the straight path and the large meander path, or the so-called Kuroshio large meander. This phenomenon is characterized by the presence of the cyclonic cold-core eddy located south of Japan, which leads to both negative and positive sea surface temperature (SST) anomalies along the southeastern coast of Japan. To clarify the atmospheric response to these SST anomalies in winter, we conducted a control experiment employing a regional atmospheric model with observed SSTs and two sensitivity experiments in which the SST boundary conditions were substituted with those corresponding to the periods of for the Kuroshio large meander and the straight path. The differences in these two sensitivity experiments showed that the surface wind response to the SST anomalies associated with the Kuroshio large meander was not only characterized by wind divergence over the cyclonic cold-core eddy, as reported previously but also wind convergence along the southeastern coast of Japan. Interestingly, this wind anomaly blew into the positive SST anomaly along the east coast of Japan at around 36°N. Similar wind anomalies along the east coast of Japan were observed in a reanalysis product. The results of the model simulation and the reanalysis product showed that during the Kuroshio large meander period, the number of rainy days increased significantly over the warm SST anomaly, while the precipitation and the number of rainy days decreased over the cyclonic cold-core eddy. Moisture budget analysis revealed that the observed decrease in precipitation was attributed to the disparity between the reduced evaporation and the anomalous horizontal moisture convergence in a region where the surface winds were divergent. This moisture convergence was mainly induced by a decrease in specific humidity, implying this change in specific humidity effectively mitigated the variation in precipitation.

The Writing in the Sand. Introducing Sandtray Work in Futures Research Supervision

This paper presents an open inquiry that embraces curiosity and vulnerability in the anticipatory space of an art-led, Futures orientated PhD supervisory relationship. We use sandtray work to elicit an anticipatory aesthetic, recording emergent data and processes through the dialogical method of duoethnography, and the visual format of photography. We seek to generate an environment that rouses imagination, creativity and futures consciousness implicit in the Australian Research Council’s definition of research. We use a duoethnographic method to collaborate, reflect and provide dialogical ways to surface deep meanings. There is a shared equity of understanding of the research process as a vehicle for engaging with the unknown. Both supervisor and supervisee hold explicit and implicit referent knowledge in relation to person and process. Therefore, it is a collaborative, reciprocal and fluid environment, where 1 + 1 = ∞ possibilities. We use sandtray to provide the location of open inquiry, dialogical reciprocation, reflection, and improvisation. This gives voice to the meaning that is made in the meandering paths between the words and an opportunity to loosen the shackles of business as usual. The sandtray moves not-known material into conscious awareness via somatic/intuitive symbol selection, engagement with metaphor, and projection; each privileging the unconscious. Introducing sandtray process into the supervisory relationship provides an alternative and adjunct modality of non-verbal inquiry that can support the calling of an anticipatory aesthetic through the Futures Senses. While there is rich, though sparse, literature describing the facilitation of sandtray work within the context of clinical supervision of mental health professionals, the introduction of such an approach within research supervision appears rare, or unique in relation to published research.

Modeling Multiphase Debris Floods Down Straight and Meandering Channels

Natural debris floods travel in straight and meandering courses. The flow behaviour greatly depends on the volume fractions of solid and fluid, as well as on their dynamic interactions with the channel geometry. For the quasi three-dimensional simulations of flow dynamics and mass transport of these floods through meandering and straight channels, we employ a two-phase debris flow model to carry out simulations for debris floods within straight and sine-generated meandering channels of different amplitudes. The results for different sinuous meandering paths are compared with that in the straight one in terms of phase velocity, downslope advection and dispersion, depths of the maxima, deposition of mass, position of front and rear parts of the solid and fluid phases, and also the flow dynamics out of the conduits. The results reveal the slowing of the flow and increase of momentary deposition of the mixture mass in the vicinity of the bends along with the increasing sinuosity. The numerical experiments are useful to better understand the dynamics of debris floods down meandering channels as seen in the natural paths of the rivers as well as already existing channels like episodic rivers in hilly regions. The results can be extended to propose some appropriate mitigation strategies.

Like the space in-between beats :a dialogue on dialogues

This article transmits a dialogue between two theatre practitioners: theatre maker Lotte van den Berg, co-founder of Building Conversation, and performer/creator Marije Nie, co-founder of the Parliament of Practices and the Cross Pollination collective. The dialogue is not an argument or a debate, it is an encounter in the space in-between, in-between our practises, experiences, professional ethos and praxis as theatre-makers. It is an exercise in inviting the swirls and eddies of thoughts and impulses and following them, with care. The text follows the meandering path of the dialogue, both an exchange and a search for a state of being together that allows thoughts to emerge and take flight while staying connected to our centres, like in a physical theatre training.

Same but different - pseudo-pectin in the charophytic alga Chlorokybus atmophyticus.

All land-plant cell walls possess hemicelluloses, cellulose and anionic pectin. The walls of their cousins, the charophytic algae, exhibit some similarities to land plants' but also major differences. Charophyte 'pectins' are extractable by conventional land-plant methods, although they differ significantly in composition. Here, we explore 'pectins' of an early-diverging charophyte, Chlorokybus atmophyticus, characterising the anionic polysaccharides that may be comparable to 'pectins' in other streptophytes. Chlorokybus 'pectin' was anionic and upon acid hydrolysis gave GlcA, GalA and sulphate, plus neutral sugars (Ara≈Glc>Gal>Xyl); Rha was undetectable. Most Gal was the l-enantiomer. A relatively acid-resistant disaccharide was characterised as β-d-GlcA-(1→4)-l-Gal. Two Chlorokybus 'pectin' fractions, separable by anion-exchange chromatography, had similar sugar compositions but different sulphate-ester contents. No sugars were released from Chlorokybus 'pectin' by several endo-hydrolases [(1,5)-α-l-arabinanase, (1,4)-β-d-galactanase, (1,4)-β-d-xylanase, endo-polygalacturonase] and exo-hydrolases [α- and β-d-galactosidases, α-(1,6)-d-xylosidase]. 'Driselase', which hydrolyses most land-plant cell wall polysaccharides to mono- and disaccharides, released no sugars except traces of starch-derived Glc. Thus, the Ara, Gal, Xyl and GalA of Chlorokybus 'pectin' were not non-reducing termini with configurations familiar from land-plant polysaccharides (α-l-Araf, α- and β-d-Galp, α- and β-d-Xylp and α-d-GalpA), nor mid-chain residues of α-(1→5)-l-arabinan, β-(1→4)-d-galactan, β-(1→4)-d-xylan or α-(1→4)-d-galacturonan. In conclusion, Chlorokybus possesses anionic 'pectic' polysaccharides, possibly fulfilling pectic roles but differing fundamentally from land-plant pectin. Thus, the evolution of land-plant pectin since the last common ancestor of Chlorokybus and land plants is a long and meandering path involving loss of sulphate, most l-Gal and most d-GlcA; re-configuration of Ara, Xyl and GalA; and gain of Rha.

Flood-Prone Zones of Meandering Rivers: Machine Learning Approach and Considering the Role of Morphology (Kashkan River, Western Iran)

We utilized the random forest (RF) machine learning algorithm, along with nine topographical/morphological factors, namely aspect, slope, geomorphons, plan curvature, profile curvature, terrain roughness index, surface texture, topographic wetness index (TWI), and elevation. Our objective was to identify flood-prone areas along the meandering Kashkan River and investigate the role of topography in riverbank inundation. To validate the flood susceptibility map generated by the random forest algorithm, we employed Sentinel-1 GRDH SAR imagery from the March 2019 flooding event in the Kashkan river. The SNAP software and the OTSU thresholding method were utilized to extract the flooded/inundated areas from the SAR imagery. The results showed that the random forest model accurately pinpointed areas with a “very high” and “high” risk of flooding. Through analysis of the cross-sections and SAR-based flood maps, we discovered that the topographical confinement of the meander played a crucial role in the extent of inundation along the meandering path. Moreover, the findings indicated that the inner banks along the Kashkan river were more prone to flooding compared to the outer banks.

Jimmy Carter, Vietnam, and the Rhetoric of Gratitude: Antecedents to the Noble Cause

Abstract The study of the Vietnam War and American presidential discourse has followed a somewhat meandering path. The Vietnam discourse of Jimmy Carter remains the most poorly understood of the late Cold War presidents. Throughout the 1970s, Carter participated in, and at times led, the national debate over the federal government's responsibility to Vietnam veterans. He spoke of a debt of gratitude that the American people owed to the war's veterans. As president, parts of his domestic agenda prioritized Vietnam veterans, leading him to preside over commemorative events for the war's veterans on several occasions. During his time in elective office, he alternatingly defined the purpose of the war in Southeast Asia as preserving the American way of life, promoting democracy, or defending liberty and freedom. Carter practiced an ethics of remembering that sought to redeem the American soldier, to erase the divisiveness of the past, and to “delegitimize and marginalize anti-war opinions.”1 Despite the obvious importance of both his discourse and his actions, Carter's Vietnam War rhetoric has received very little attention.

Why Did the 2017 Kuroshio Large Meander Event Become the Longest in the Past 70 Years?

AbstractThe Kuroshio south of Japan is known to vacillate between a straight and a large meander (LM) path. Since 1950, eight LM events have been observed with different durations. The most recent/on‐going LM started in August 2017 and has become the longest event in record. By analyzing eddy‐resolving sea surface height data and by adopting a wind‐forced linear vorticity model, we demonstrate that the on‐going LM is maintained by an exceptionally stable dynamic state of the Kuroshio Extension (KE) forced by wind stresses across the Pacific basin. The highly‐stable KE system not only minimizes westward eddy perturbations from disrupting the upstream Kuroshio path, its strengthened southern recirculation gyre further helps to anchor the Kuroshio across the Izu Ridge. By contrasting the on‐going event to the 2004–2005 event, we argue that the LM duration is more sensitive to the wind‐forced KE dynamic state than the eastward Kuroshio transport south of Japan.

Subtropical Mode Water in a recent persisting Kuroshio large-meander period: part II—formation and temporal evolution in the Kuroshio recirculation gyre off Shikoku

Since August 2017, the large meander (LM) path of the Kuroshio south of Japan has continued to date for more than five years, with a local Kuroshio recirculation gyre off Shikoku (RGOS). The formation and temporal evolution of Subtropical Mode Water (STMW) in the isolated RGOS were examined by using Argo profiling float and shipboard observation data. Since the late winter of 2018, which was the first winter of the current LM event, multiple STMW layers with different densities overlapping with each other have been observed for more than three years inside the RGOS. The deeper STMW layer of 18.0 °C, which was formed in the late winter of 2017 before the current LM event began, has survived at least until September 2021 while its thickness and horizontal extent has decreased gradually. We may have succeeded in discovering the longest survived STMW ever observed due to a suitable environment for STMW conservation inside the RGOS. On the other hand, the shallower STMW layer(s) of 19.0–19.8 °C, which was originally formed over the deeper STMW layer in the late winter of 2018, has been repeatedly renewed or dissipated in the following years. The oxygen utilization rate at the core of the deeper STMW at a depth of 500 dbar was estimated to be 4.6 μmol kg−1 yr−1, which is believed to be explained solely by oxygen consumption due to remineralization.

Imagery in Katherine Mansfield's Short Story "Bliss"

Since the death of Katherine Mansfield, the kind of attention
 
 her short stories have received has followed an understandably
 meandering path. There is no doubt that she joins D.H.Lawrence and
 Aldous Huxly among others in parading those she knew in real life
 through the pages of her fiction-and no one more consistently than
 herself.(Magalaner,p.413).
 
 The vision of the human condition which emerges from
 Katherine Mansfield's stories is a painful one. It is predicated upon the
 notion that to be human is to be a victim and that life preys upon those
 least capable of defending themselves against the impossible and
 intolerable situations it presents. Each stage and condition of life has
 inescapable situations peculiar to it. Women are victimized by the basic
 fact of their sex: demanding and insensitive men brutalize them, child
 birth exploits them, and female self-sacrifice is regarded by the male
 world as routine and expectable. The young and naïve are victimized by
 the process of learning the lessons life waits to teach: the fact of death,
 the relentless passage of beauty and vigor, the disappointment of
 idealism. The old are victimized by loneliness and sickness,by fear of
 death,by the thoughtless energy of the younger world around
 them.Mansfield's sympathies are torn between her commitment to life
 itself, the potential beauty of experience,and the apparent denial of that
 potential beauty when the chips are down.
 
 To enter into a relationship with another person is,according to
 Mansfield,to be victimized by the one most loved,most trusted .The only
 option is to become a victimizer,to inflict the pain,betray the trust.

조선통신사 국내루트의 역사문화콘텐츠 고찰

In this article, the historical and cultural contents of the domestic route of the Joseon Tongsinsa were reviewed with the records of the Joseon Tongsinsa. First, the domestic route of the Joseon Tongsinsa was organized by comparing the official route proposed by Yang Hyo-sung, 1-jin 1-po 32, with the current administrative district. Based on this, the historical and cultural contents of the Joseon Tongsinsa were classified into place contents, person contents, and festival events. The location contents were divided into five sections: Seoul, Gyeonggi-do, Chungcheongbuk-do, Gyeongsangbuk-do, Ulsan, and Busan, and the main areas of each section were derived. Moreover, the historical meaning and current address were also considered. In the character content and festival events, the direction of historical and cultural content that local governments related to the domestic route where the Joseon Tongsinsa event took place was presented. Among the historical and cultural contents of Joseon Tongsinsa considered in this article, the place contents will be particularly important if a physical restoration of the Joseon Tongsinsa's meandering path is carried out in the future.

Sprinkle lunacy over legs: A review of WoW workshop writing exercises

In the summer of 2021 I organized and facilitated a short series of three online workshops to launch the Ways of Writing in Art and Design Research Network (WoW). This article reviews the collaborative writing exercises I devised for the workshops, designed to explore potential approaches to writing in/on/about/beside/with art and design beyond the conventional academic essay and in relation to the condition and experience of living and working through the COVID-19 pandemic and subsequent lockdowns. The article adheres to academic convention in its presentation and format, while gently pushing against academic orthodoxies in its playful execution, as the text is interwoven with anecdotal asides, subjectivity, description and metaphor. Alongside familiar staples of academic art writing, such as Barthes and Csikszentmihalyi, I draw on a broader range of resources that include poetry and song lyrics. Rather than set out to efficiently argue or prove a point or position, the writing takes a more meandering path (it is littered with the academically maligned word ‘perhaps’) that resembles the ‘carrier bag’ approach of the gatherer, rather than the target driven spear trajectory of the hunter.

Dancers, Mountains, and People in the Fields

Dancers, Mountains, and People in the Fields

Optimal Precursor Triggering Kuroshio Large Meander Decay Obtained in a Regional Ocean Model

AbstractThis study investigates the optimal precursor (OPR) triggering Kuroshio large meander (LM) decay using a conditional nonlinear optimal perturbation (CNOP) approach and a regional ocean modeling system (ROMS). The results show that the large amplitudes of the OPR are mainly concentrated at 1,000–2,500 m in the LM upstream region (west of 137°E), and their propagation downstream along the Kuroshio axis contributes to triggering the transition from the LM path to the nonlarge meander (NLM) path. Using the growth of the OPR, it is found that baroclinic instability contributes to the fast vertical development of the perturbations in the early stage of the LM decay, while barotropic processes play a leading role during the cyclonic ring shedding of the LM decay. In particular, the LM decay process is evaluated by the depth‐integrated vorticity equation, implying that the advection term dominates over the beta effect in the LM decay. Furthermore, the vorticity balance associated with the cyclonic eddy indicates that the advection and divergence terms represent a main balance in the spin‐down process of the cyclonic eddy. Under the effects of both, high potential vorticity water flows out from the LM meander tip and then the amplitude of the LM experiences a remarkable decrease. With the detachment of a cyclonic ring, a transition from the LM path to the NLM path occurs. This study further deepens our understanding of the LM decay and provides us some useful hints about designing the observation system of the LM.