bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of interference among parallel absorbers on acoustic characteristics of an absorbing panel
Authors: Han Lei , Ji Hongli , Qiu Jinhao
Published: June 2021

This paper proposes a modified theory for synthesizing the acoustic impedance of an absorbing panel by considering the interference among parallel absorbers. The absorbing panel comprises periodically distributed absorbers with different acoustic characteristics, and the periodic distribution allows the impedance of the panel to be characterized by that of a unit cell. However, at frequencies between the resonances of the absorbers in the unit cell, the unit-cell impedance given by traditional theory deviates significantly from that given by a finite-element model. Inspecting the flow field near the surface of the unit cell reveals that the out-of-phase flow plays an important role in the interaction among the parallel absorbers and induces the deviation. A modified theory is proposed by multiplying the original resultant impedance by a factor that considers the interaction. The modified theory is verified by numerical results for several typical absorbing panels with different patterns of unit cells and different geometrical parameters of absorbers, and experimental validation is also carried out. As further evidence for the correctness and universality of the modified theoretical model, a comparison is presented with the mutual-radiation-impedance theoretical model based on a Helmholtz resonator array panel. The results of validation on different absorbing panels and the comparison with the mutual-radiation-impedance method show that the modified theoretical model is better at predicting the absorption coefficient than is the traditional theory.
Printed flexible supercapacitor: Ink formulation, printable electrode materials and applications
Authors: Liang Jing , Jiang Changzhong , Wu Wei
Published: June 2021

Flexible supercapacitors (FSCs) have attracted extensive attention due to their lightweight, easy integration, high power density, fast charge/discharge rate, and safe features. Printed FSC has provided an economical and simple solution for the fabrication of FSCs different from the traditional manufacturing methods. The successful preparation of printed FSCs mainly depends on the formulating of functional inks and designing of innovative electrode materials. Here, we reviewed the recent development of the ink's formulation principle, printable electrode materials, and integrated application of FSCs devices. The inks with excellent rheological properties, acquired by tuning the components (including binders, additives and solvents), are first introduced to match different printing techniques. The design of printable electrode materials is also highlighted, focusing on electrical double-layer capacitive carbons, pseudocapacitive materials (metal oxides, conducting polymer, etc.), and the newly emerging materials (MXenes, etc.). We concluded that 3D printing and new printable electrode materials will be key in successfully designing next-generation printed FSC with high energy and high power, and thus offer general guidelines to its integrated applications.
Locally active memristor based oscillators: The dynamic route from period to chaos and hyperchaos
Authors: Ying Jiajie , Liang Yan , Wang Guangyi , Iu Herbert Ho-Ching , Zhang Jian , Jin Peipei
Published: June 2021

To explore the complexity of the locally active memristor and its application circuits, a tristable locally active memristor is proposed and applied in periodic, chaotic, and hyperchaotic circuits. The quantitative numerical analysis illustrated the steady-state switching mechanism of the memristor using the power-off plot and dynamic route map. For any pulse amplitude that can achieve a successful switching, there must be a minimum pulse width that enables the state variable to move beyond the attractive region of the equilibrium point. As local activity is the origin of complexity, the locally active memristor can oscillate periodically around a locally active operating point when connected in series with a linear inductor. A chaotic oscillation evolves from periodic oscillation by adding a capacitor in the periodic oscillation circuit, and a hyperchaotic oscillation occurs by further putting an extra inductor into the chaotic circuit. Finally, the dynamic behaviors and complexity mechanism are analyzed by utilizing coexisting attractors, dynamic route map, bifurcation diagram, Lyapunov exponent spectrum, and the basin of attraction.
Orientation and size effects on electronic structure of rectangular cross-sectional Sn nanowires
Authors: Sato M. , Tanaka H. , Kimoto T.
Published: June 2021

The band structures of Sn nanowires with various cross-sectional shapes and orientations were calculated by a tight-binding method. The wave functions of bulk Sn and Sn nanowires were also analyzed. The calculation revealed that the conduction band minimum of some Sn nanowires originates from the electronic states in the valence band of bulk Sn. This behavior was discussed in terms of the dependence on the orientation and cross-sectional shape of Sn nanowires. In addition, we clarified that the [110]-oriented nanowires with a narrow (001) sidewall and [111]-oriented nanowires have the lightest effective mass among the considered nanowires.
Dual modulation STM: Simultaneous high-resolution mapping of the differential conductivity and local tunnel barrier height demonstrated on Au(111)
Authors: Oldenkotte V. J. S. , Witmans F. J. , Siekman M. H. , de Boeij P. L. , Sotthewes K. , Castenmiller C. , Ackermann M. D. , Sturm J. M. , Zandvliet H. J. W.
Published: June 2021

We present a scanning tunneling microscopy (STM) technique to simultaneously measure the topography, the local tunnel barrier height (dI/dZ), and the differential conductivity (dI/dV). We modulate the voltage and tip piezo with small sinusoidal signals that exceed the cut-off frequency of the STM electronics and feed the tunneling current into two lock-in amplifiers (LIAs). We derive and follow a set of criteria for the modulation frequencies to avoid any interference between the LIA measurements. To validate the technique, we measure Friedel oscillations and the subtle tunnel barrier difference between the hcp and fcc stacked regions of the Au(111) herringbone reconstruction. Finally, we show that our method is also applicable to open feedback loop measurements by performing grid I(V) spectroscopy.
Drop-to-drop liquid–liquid extraction of DNA in an electrowetting-on-dielectric digital microfluidics
Authors: Paul Shubhodeep , Moon Hyejin
Published: June 2021

Recent advancements in microfluidics and lab-on-a-chip technologies enabled miniaturization and automation of many downstream nucleic acid analysis steps such as PCR. However, DNA extraction/isolation protocol remains a stand-alone sample preparation step. For a quick sample-to-result solution, downstream protocols and sample preparation protocols need to be seamlessly integrated into a single lab-on-a-chip platform. As a step toward such integration, this paper introduces microfluidic DNA isolation using the liquid–liquid extraction (LLE) method in the drop-to-drop (DTD) format. The electrowetting-on-dielectric digital microfluidic platform is capable of handling a two-phase liquid system easily, which enables DTD LLE. In this study, the extraction of plasmid DNA (pDNA) from an aqueous sample to an ionic liquid is demonstrated. Prior to pDNA extraction study, the DTD LLE protocol was developed and optimized using organic dyes as solutes. The selective extraction of pDNA in the presence of proteins as interfering molecules is also demonstrated. This work implies that DTD LLE can substitute for magnetic beads steps in standard DNA isolation protocols.
On the temperature-dependent characteristics of perpendicular shape anisotropy-spin transfer torque-magnetic random access memories
Authors: Zhang Wei , Tong Zihan , Xiong Yuzan , Wang Weigang , Shao Qiming
Published: June 2021

The perpendicular shape anisotropy-spin transfer torque-magnetic random access memories (PSA-STT-MRAMs) take advantage of the nanopillar free-layer geometry for securing a good thermal stability factor from the shape anisotropy of the nanomagnet. Such a concept is particularly well-suited for small junctions down to a few nanometers. At such a volume size, the nanopillar can be effectively modeled as a Stoner–Wohlfarth particle, and the shape anisotropy scales with the spontaneous magnetization by ∼Ms2. For almost all ferromagnets, Ms is a strong function of temperature; therefore, the temperature-dependent shape anisotropy is an important factor to be considered in any modeling of the temperature-dependent performance of PSA-STT-MRAMs. In this work, we summarize and discuss various possible temperature-dependent contributions to the thermal stability factor and coercivity of the PSA-STT-MRAMs by modeling and comparing different temperature scaling and parameters. We reveal nontrivial corrections to the thermal stability factor by considering both temperature-dependent shape and interfacial anisotropies. The coercivity, blocking temperature, and electrical switching characteristics that resulted from incorporating such a temperature dependence are also discussed, in conjugation with the nanomagnet dimension and coherence volume.
No observation of lead hydride in the Pb–H system under pressure up to 140 GPa
Authors: Guigue Bastien , Loubeyre Paul
Published: June 2021

The possibility of high pressure formation of lead hydrides has been investigated through the direct reaction of lead with hydrogen in a laser-heated diamond anvil cell. Synchrotron x-ray diffraction was used to detect any structural changes and volume expansion due to hydrogen absorption in the Pb metal. The compression curve of lead embedded in helium, measured under the same experimental conditions, was used as a reference. No volume expansion of the Pb lattice was measured, hence indicating no formation of an interstitial hydride. The observed structural changes match those of pure lead with the sequence of compact structures fcc, hcp, and bcc. The PbH6 and PbH4 compounds, found by various crystal structure prediction calculations to be stable below 140 GPa, were not observed. Lead seems very reluctant to absorbing hydrogen, which could be used for plating materials to resist hydrogen embrittlement under extreme conditions.
The dynamic epigenetic regulation of the inactive X chromosome in healthy human B cells is dysregulated in lupus patients
Authors: Pyfrom Sarah , Paneru Bam , Knox James J. , Cancro Michael P. , Posso Sylvia , Buckner Jane H. , Anguera Montserrat C.
Published: June 2021

Significance

Pathogenic autoantibodies are a feature of systemic lupus erythematosus (SLE), of which 85% of patients are women. Multiple X chromosomes increase the risk for SLE, suggesting an important role for X-linked gene expression for the female sex bias. X-chromosome inactivation (XCI) regulates X-linked gene expression on the inactive X. This study examines XCI maintenance across multiple human B cell subsets from healthy individuals and SLE patients. Importantly, we found that both pediatric and adult SLE patient B cells have significant reductions with epigenetic modifications on the inactive X and aberrant X-linked gene expression. Our findings will be instrumental for future investigations of disease mechanisms underlying the female bias of SLE and abnormal autoantibody production in B cells.
Selective filtering of excitatory inputs to nucleus accumbens by dopamine and serotonin
Authors: Christoffel Daniel J. , Walsh Jessica J. , Hoerbelt Paul , Heifets Boris D. , Llorach Pierre , Lopez Ricardo C. , Ramakrishnan Charu , Deisseroth Karl , Malenka Robert C.
Published: June 2021

Significance

Dopamine (DA) and serotonin (5-HT) release in the nucleus accumbens (NAc) influence motivated behaviors, yet the mechanisms by which they modulate NAc activity are unclear. Here, we report that DA selectively reduced excitatory postsynaptic currents (EPSCs) from paraventricular thalamus (PVT) inputs, whereas 5-HT reduced EPSCs from PVT, ventral hippocampus (vHip), and basolateral amygdala (BLA) inputs but not medial prefrontal cortex (mPFC) inputs. Mimicking the input-specific effect of DA via optogenetic inhibition of the PVT promoted cocaine-conditioned place preference, while inhibition of the mPFC blocked the enhancement of sociability induced by (±)3,4-methylenedioxymethamphetamine (MDMA). Together, these results suggest that these input-specific effects on NAc excitatory transmission contribute to the distinct modulation of behavior that is generated by release of DA and 5-HT.
Filtration of 2-particles suspension in a porous medium
Authors: Kuzmina L I , Osipov Yu V , Astakhov M D
Published: June 2021

Abstract During the construction of underground storage of hazardous waste, it is necessary to create waterproof walls in the ground. The grout is filtered in the rock, fills the pores and, when hardened, creates a reliable barrier to groundwater. A one-dimensional model of the flow of inhomogeneous particles in a porous medium is considered. The retained particles profiles formed during deep bed filtration are studied. It is shown that when filtering a 2-particle suspension, the deposit is distributed unevenly. The profile of large retained particles is always monotonous, and the profile of small retained particles is nonmonotonic. The monotonicity of the total deposit profile depends on the model parameters. The shape of non-monotonic profiles is time-dependent. At short times, the profile decreases monotonously. At some point, a maximum appears on the profile graph, which shifts from the inlet to the output with increasing time. When the maximum point reaches the outlet, the profile becomes monotonically increasing. With a further increase in time, the retention profiles remain monotonically increasing. Analytical solutions for a filtration model with particles of three or more different types are unknown. Analysis of the retention profiles of the polydisperse suspension requires further study.
Stress state of an earth dam under main loads considering data from field observations
Authors: Salyamova K D , Turdikulov Kh Kh
Published: June 2021

Reliable and safe operation of hydro-technical structures (earth dams), in the seismic regions of the republic, requires researchers to constantly improve the calculation methods in accordance with the requirements of regulatory documents for basic and special combinations of loads, including seismic ones. A calculation method is proposed for estimating the stress state on the example of an earth dam of the Charvak HPP (in operation for 47 years) in a plane elastic statement under main loads, taking into account the real piecewise-inhomogeneous physical and mechanical characteristics of soil of the structure body. Individual results of solving the problem were compared with the data of long-term field observations. The calculation method allows determining the kinematic characteristics (displacements, settlements, stresses, pore pressure) of an earth dam, which makes it possible to predict the state of the most vulnerable places in the structure and, if necessary, to develop appropriate measures to strengthen them. The problem was solved by the numerical finite element method. According to the developed technique, the problem by the numerical finite element method was reduced to solving a system of linear equations relative to the desired displacements. The calculation results are presented in the form of isolines of the stress-strain state of the dam body under the main loads (gravitational forces, hydrostatics). The numerical results of solving the problem and their comparison with the data of field observations make it possible to determine the reliability of the developed methods and software and thereby determine the vulnerable zones of the earth dam, where the loss of stable operation of the structure is possible. Based on the research results, appropriate recommendations were made.
Mathematical modeling of one-dimensional air movement with dispersed particles in a continuously working pneumatic mixer
Authors: Uvarov V A , Orekhova T N , Chekhovskoy E I , Kachaev A E
Published: June 2021

The improvement of methods and technologies for the production of dry building mixes, dispersed modifiers, dry paints and other finely ground, homogeneous systems is associated with the quality of their compositions, which, in turn, requires the use of high-tech energy-saving equipment. The use of the original pneumatic mixers proposed in the paper makes it possible to obtain high-quality multicomponent mixtures due to the specially organized movement of the two-phase flow meeting with the peripheral supply of the energy carrier. Forecasting and analyzing the dynamics of two- and multiphase systems distributed in the air in units of this type allows assessing the nature of the technological process of mixing components, while a mathematical description of the complex movement of particles in the air flow allows obtaining a result that helps to characterize the operating modes of the pneumatic mixer, which is important when operating this machine in production. The paper presents a method for numerical simulation of the axisymmetric motion of a two-phase flow in the homogenization chamber of a pneumatic mixer, which allows setting adequate operating modes of the unit for various dispersed systems mixed in it. The main assumptions in the construction of the mathematical model are also reflected, the conditions for setting the problem for this study are formulated, and the results are obtained in the form of analytical expressions of the main dynamic parameters of the flow with particles for the volume of the mixing chamber, depending on the design features of the pneumatic mixer.
Ratio of the ash concentration to the cement binder in the composition of concrete with the use of a modified additive
Authors: Lukpanov R E , Dusembinov D S , Yenkebayev S B , Tsygulyov D V
Published: June 2021

The paper presents studies of cement-ash binder in the composition of concrete with the use of a complex modified additive (CMA). The research is aimed at improving the conditions for the production of concrete works, in particular, improving the workability of a concrete mixture based on ash-cement binders. The main evaluation criterion of the study was the change in the viscosity of the composition with a change in the water-binding ratio. The measurements were carried out in two stages: at the first stage, the influence of the ash component on the water-binding ratio was estimated, at the second stage, the issue of changing the viscosity over time was considered. Laboratory tests were carried out using adapted methods for measuring the spread of the mixture and determining the setting time. According to the results of the first stage, the regularities of changes in the viscosity of the mixture by changing the water content were obtained, and the optimal ratios of water to the binder were obtained, depending on the percentage of the ash component. According to the results of the second stage, the regularities of changes in the viscosity (from the liquid to the solid state) of the mixture over the holding time, depending on the same percentage of ash were obtained. In conclusion, the data on the optimal water-binding ratio from the conditions for the manifestation of the ash-cement mixture of texotropic properties corresponding to the classical cement mixture, without the inclusion of ash, are presented.
Reduction of plane-radial freezing - thawing problems to plane-parallel ones
Authors: Aksenov B G , Abrosimova S A , Rydalina N V
Published: June 2021

Construction in northern conditions is complicated by the processes of seasonal freezing and thawing of soils. This factor is of particular importance in the area of permafrost distribution. The paper deals with the problems that arise when laying communication networks. Any engineering solution must be justified by a heat engineering calculation. In one case, it is necessary to exclude the thawing of water or sewer networks, in the other case – to prevent the destructive effect of the heating main on the permafrost soil. The most common mathematical model of the heat transfer process in the presence of phase transitions is the Stefan problem. When calculating the processes of freezing-thawing near the pipes of communications, it is rational to set the problem in cylindrical coordinates, using the property of plane-radial symmetry. But the Stefan problem has an exact solution only in Cartesian coordinates, for the case of plane-parallel symmetry. For this case, many approximate dependencies are also obtained. The paper presents a method that allows using the results of solving the plane-parallel Stefan problem to solve the plane-radial problem with the same values of the input parameters. Approximate values of the coordinate of the phase transition front as a function of time for the plane-parallel and plane-radial areas are obtained using the method of sequential change of stationary states. A one-to-one relationship is established between the obtained values. If there is a solution obtained by any method for a plane-parallel area, and then using this dependence, it can be applied to a plane-radial area. This technique is suitable not only for the Stefan problem, but also for many nonlinear heat conduction problems. The results given in the paper are of practical importance: using the above method, almost any solution obtained for one type of symmetry directly extends to other types of symmetry.
The model of formation of the spatial organization of shift settlements
Authors: Kh Ishmametov R
Published: June 2021

The purpose of the study contains two main aspects: - improvement of the spatial organization of the shift settlement of the oil and gas industry - the potential of the structure-forming component of the country’s settlement system; - development of the optimal functional and planning structure of the morph types of the shift settlements, providing a high level of comfort that meets the increasing needs of a modern, dynamically developing society. Comprehensive review of the existing forms of spatial organization of shift settlements is carried out on the example of foreign and domestic experience in the design, construction and operation of shift settlements at various stages of development in order to identify the intensity of their formation and determine the most perspective type, as a basis for development and the subject of further research. The vector of external and internal, first of all, production -technological and social factors influencing the morphology of shift settlements and the structure of territorial settlement in the system of industrial development of the natural complex is determined. The evolutionary transformations of the morphology of shift settlements in all countries took place taking into account the factors and characteristics of natural-geographical, climatic, socio-economic aspects and functional-industrial affiliation. Considered the circumstances and features of formation of the architectural and planning organization of shift settlements that affect the creation of an algorithm of gradual development through modernization the quality of its internal spatial structure. The increasing technological potential of the territories stimulated to the formation of typological and classification diversity of the territorial structure and spatial organization of shift settlements, their morphological and taxonomic hierarchy. On the basis of a concept formulated a predictive theoretical model of the holistic shift space settlements, with the functional program of the formation of the quality of the environment is comparable to quality of life in large urbanized space with respect to information-technology resource of the modern world, shaping the potential for sustainable development.
Features of thermal decomposition of titanium hydride fraction
Authors: Pavlenko V I , Yastrebinsky R N , Bondarenko N I , Kuprieva O V
Published: June 2021

One of the areas of work on the technology of producing products based on titanium hydride fraction HTK-D is the study of methods and modes of modifying the surface of titanium hydride fraction in order to increase its thermal stability at high temperatures and protect titanium from oxidation. The research was carried out using modern instrumental physical methods and physical and chemical analyses. Differential thermal and thermogravimetric analyses of the initial and modified titanium hydride fractions were performed in the temperature range of 20-1000 °C in the air atmosphere. The curves TG and DTG of the initial fraction of titanium hydride show a slight change in mass in the temperature range of 20-100 °C with a maximum at T– 82 °C, which is associated with the removal of sorbed moisture. The data of the DTG analysis showed that the modification of the titanium hydride fraction with sodium borosilicate leads to a noticeable decrease in the mass loss of the samples: in the temperature range of 600-900 °C, the mass loss for the modified titanium hydride fraction was 0.39 and 1.58% (wt.) for the initial fraction of titanium hydride. In the course of the experiment, it was revealed that a further increase in the temperature leads to an increase in the mass of titanium hydride fraction samples, which is a consequence of titanium oxidation. It was found that the modification of the titanium hydride fraction with sodium borosilicate increases its thermal stability.
Joukowski’s wake model for tip-splitting rotors
Authors: Castillo-Castellanos A , Durán Venegas E , Le Dizés S
Published: June 2021

The interaction between a tip vortex and a solid surface is responsible for premature structural component fatigue in wind turbines and undesirable noise in helicopter rotors during low speed and descending flight. One noise reduction strategy uses a modified airfoil to split and spread the vorticity in two tip vortices. The present paper aims to provide the wake structure produced by such a rotor for wind turbine and helicopter regimes. We use a filamentary approach, such that vortices are assumed to roll-up quickly to form thin vortex filaments of finite but small size and compute the induced velocity using a cut-off method. The structure of the wake is analyzed in the near- and far-fields separately. It is found to have a dual nature and to be well-described by a twisted vortex pair locally aligned along with a larger helical structure. The linear stability of the far-wake with respect to long-wave displacements is also analyzed. Two kinds of instability modes are obtained associated with a pairing between successive turns of the large helical structure and a pairing between successive turns of the vortex pair.
Deformation and wake of a flexible rotor in water
Authors: Eldemerdash A S , Leweke T
Published: June 2021

In this paper, we study experimentally the fluid-structure interaction of a simplified small-scale rotor operating in a water channel. The rotor consists of a single untwisted rectangular blade and is tested with various pitch angles at different rotation speeds and free stream velocities. Flapwise blade deformations are measured using image processing, and flow fields are obtained by Particle Image Velocimetry. The blade exhibits extreme downstream and upstream bending at high negative and positive pitch angles, respectively. In addition, for negative pitch angles, unsteady flapwise fluctuations are observed, accompanied by large-scale recirculation zones. These zones are formed and shed periodically behind the rotor, resembling the dynamics of the Vortex Ring State known for helicopters in steep descent. The induced axial velocity near the blade tip changes direction from upstream to downstream, in accordance with the bending direction, reaching values that exceed twice the free-stream velocity in extreme bending conditions. The blade deformation has a strong dependence on the tip speed ratio for low pitch angles, and a more pronounced dependence on the tip Reynolds number for high pitch angles. Results for a two-bladed rotor are also shown and compared to the behaviour observed for a single blade.
Wind turbine wake inflow over a heterogeneous forest - comparison between measurement and LES simulation
Authors: Navarro Diaz Gonzalo P. , Arnqvist Johan , Ivanell Stefan
Published: June 2021

In this work a new step in understanding the wind turbine (WT) wake behavior on forested areas is made. For this analysis, a pair of real scale WTs located on a site with moderately complex terrain and heterogeneous forest is simulated using Large Eddy Simulation (LES). This simulation is compared with met mast and power output measurements of two WTs in Ryningsnas, Sweden, considering near neutral stratification in the atmospheric boundary layer (ABL). Three validation steps are followed; first, the undisturbed wind profile is compared with met mast data and another similar LES code. Then, the wake for each WT wake impacting on the met mast at different directions is addressed. A feature of this pair of WTs is that these have different hub heights, but the same rated power and rotor diameter, which helps provide insight into how the tip clearance over the forest affects the operation and wake characteristics. Finally, power output deficits when the WTs are operating in each others wakes are compared to observed power deficits. For these simulations SOWFA, the Open FOAM project for wind farms simulation in ABL, is used. In this code, three new additions are made; the forest model, the mesh modification for complex terrain and the representation of the WT using an actuator disc model with local force adaptation for wind farm flows. The simulation results show a good performance on quantitatively and qualitatively capturing the velocity in the wake, but for TKE the simulation underestimates the magnitude, and fails to match the measured structure of the wake for one of two WTs. The power deficit on the impacted WTs is well captured, despite the complexity related to turbines with different hub heights. This study makes one of the first steps on validating LES simulations for wind farms in forest.
A Quantitative Comparison of Aeroelastic Computations using Flex5 and Actuator Methods in LES
Authors: Hodgson E L , Andersen S J , Troldborg N , Forsting A Meyer , Mikkelsen R F , Sørensen J N
Published: June 2021

Actuator disc and actuator line techniques are widely used for modelling wind turbines operating in wind farms. These techniques essentially replace the blade geometry with applied body forces, which reduce the resolved length scales significantly and hence the required grid resolution. This work is a verification of the coupling between the flow solver EllipSys3D and the aeroelastic tool Flex5, through a quantitative comparison of coupled actuator line, coupled actuator disc, and standalone Flex5. Steady state performance predictions, instantaneous reaction to turbulence and damage equivalent load analyses all show a very good agreement between the three methods. Differences can be explained primarily by the higher fidelity modelling of the coupled simulations; this is particularly in regard to the influence of blade flexibility, as the actuators deflect and interact with the modelled flow. Additionally, some overpredictions of loading at the blade tip and root below rated velocity for the actuator methods can be attributed to the Gaussian smearing used to apply the body forces.
Evaluating wind farm wakes in large eddy simulations and engineering models
Authors: Stieren Anja , Stevens Richard J. A. M.
Published: June 2021

We study wind farm wakes with large eddy simulations (LES) and use these results for the evaluation of engineering models such as the Jensen model, the coupled wake boundary layer model (CWBL), the Turbulence Optimized Park model (TurbOPark), and the wind farm model developed by Niayifar and Porté-Agel (Energies 9, 741 (2016)). We study how well these models capture the wake effects between two aligned wind farms with 72 turbines separated by 10 kilometers in a neutral boundary layer. We find that all considered models over-predict the wind farm wake recovery compared to what is observed in LES. The TurbOPark model predictions on the wind farm wake effect are closest to the LES results for the scenario considered here.
Feasibility assessment of climate change adaptation options across Africa: an evidence-based review
Authors: Williams Portia Adade , Simpson Nicholas Philip , Totin Edmond , North Michelle A , Trisos Christopher H
Published: June 2021

Considering the feasibility and effectiveness of adaptation options is essential for guiding responses to climate change that reduce risk. Here, we assessed the feasibility of adaptation options for the African context. Using the Global Adaptation Mapping Initiative, a stocktake of adaptation-related responses to climate change from the peer-reviewed literature in 2013–2020, we found 827 records of adaptation actions in Africa. We categorised and evaluated 24 adaptation options and for each option, six dimensions of feasibility were considered: economic, environmental, social, institutional, technological, and evidence of effectiveness. Over half (51%) of all adaptation actions were reported in the food sector where sustainable water management (SWM) was the most reported option. The fewest actions were reported for cities (5%). The majority of actions (53%) were recorded in just six countries: Ghana, Ethiopia, Kenya, Tanzania, Nigeria and South Africa. Encouragingly, effectiveness was assessed as medium or high for 95% of adaptation options. However, no options had high feasibility on any other dimension. Technological and institutional factors present major barriers to implementation. Crop management, SWM, sustainable agricultural practices, agroforestry, livelihood diversification, ecosystem governance and planning, health governance and planning, infrastructure and built environment, all had moderate feasibility across three or more dimensions. Human migration has low feasibility but high potential for risk reduction. Major knowledge gaps exist for environmental feasibility, for assessing adaptation limits at increasing levels of climate hazard, for economic trade-offs and synergies, and for Central and Northern Africa. Our results highlight sectors where enablers for adaptation can be increased. Future assessments can apply the method established here to extend findings to other national and local levels.
The arrangement of Hamdan Sukaraja Slum Settlements in Medan Indonesia, through the concept of affordable vertical village
Authors: Tanjung Z , Fitri I
Published: June 2021

Initially, the city of Medan consisted of villages, often called urban villages, which evolved to form cities. Sukaraja and Hamdan villages are old villages that are part of the Sultanate of Deli and reflect the sociocultural character of the local people of Medan. Now, these villages have grown to the banks of the Deli River. The residents choose to live in riverbank areas that are not well-designed and create unhealthy slums that have social, economic, and cultural problems. These villages will be displaced soon by the discourse of the toll project in the city of Medan on the Deli River. This paper aims to analyze and provide solutions to the problems of the development of slums in the Deli River area. Both environmental, architectural, social, and economic issues of the population. Based on data analysis, the people of Hamdan and Sukaraja villages need livable housing at an affordable cost and can support the community’s economy. This study recommends a vertical village design with an Ecological Architecture approach and integrated with sustainable economic systems. The vertical village design also accommodates the economic empowerment of Sukaraja and Hamdan villagers by developing and integrating businesses that have grown previously in this village.
Identification building mass pattern placement in the central government complex
Authors: Ashila T I , Kridarso E R , Iskandar J
Published: June 2021

Central governement complex is a place for organazing politics and adminitrative activities between government and society. Central government complex consists of some buildings that are adjusted to the organizational structure of the government, accompenied by its facilities and infrastructure. Each central government area should have a certain pattern that is considered the most suitable for its site. Determination of the pattern and the placement of building masses in the central government complex is important, because of its effect on the effectiveness and efficiency of the activities in it. This study uses a qualitative-comparative method by comparing the complex’ patterns and building mass placement at Tangerang Regency Government Center, Bandung Regency Government Center, Sejong City Administrative Complex, South Korea, and Tamar Government Center Complex, Hong Kong. This study results in an alternative range of optimal building mass pattern placement in the central government complex.
Comparative analysis of the flexural capacity of conventional steel beams with Castellated beams
Authors: Barkiah I , Darmawan A R
Published: June 2021

South Kalimantan, especially Banjarmasin City, has a thick layer of soft soil. Low bearing capacity is a major issue in planning the structure. Castellated beam is an innovation to create high structural capability with low weight. This research aims to gain the effect of the hexagonal opening angle on the bending capacity of the castellated beam. The research was conducted by numerical testing using ANSYS. This research compares the flexural capacity of conventional steel beams to the geometric effect of castellated beam with hexagonal opening angle variations. This research concluded that the geometric effect of a castellated beam can provide an increase in flexural capacity of about 8 to 19% compared to conventional steel beams. The optimum bending capacity is at the hexagonal opening angle of 45° to 50°. At the 60° opening angle, the castellated beam has decreased its flexural capacity.
Lost space as an inhibiting factor for city sustainability
Authors: Tharziansyah M , Sarbini G N , Nurfansyah N
Published: June 2021

The formation of urban slums is caused by a culture of irregular configuration of land arrangements. Many are found in old cities, does not correspond to urban planning, including in Banjarmasin. Irregularity in land patterns and natural conditions of swamps and river flows, forces organic linear development, following patterns of roads and river flows. The formation of lost spaces makes it difficult to develop sustainable cities. This study aims to see how the pattern of lost space in the city of Banjarmasin causes the formations of irregular areas and spaces within the cityscape, which make the cityscape even worse. The unit of analysis is divided by subdistrict areas. The focus of the research lies in lost space which is categorized based on the level of accessibility that is low or difficult to reach. Data collection methods include, 1) common data collection to reveal preliminary conditions; 2) field observation and literature study; 3) field survey; and 4) mapping and measuring. Data of lost spaces are compiled into 2 parts accordingly to its positions and dimensions. Methods of urban solid and void are used to identify forms of lost spaces. Analysis of lost spaces are categorized in three conditions, 1) mild; 2) moderate; and 3) severe. Almost all districts in Banjarmasin has lost space units; Central Banjarmasin District 87 spots, West Banjarmasin 60, South Banjarmasin 51, North Banjarmasin 62, East Banjarmasin 79. A lot of lost space is located some distance from the main road, while the most size is more than 1000 m2. There are 5 types of lost space: square, rectangular, L shaped, U shaped, and irregular. The irregular shape is very dominant. The results of this research show that such a wide lost space, difficult position and irregular shape is very difficult in the arrangement of a sustainable city of Banjarmasin.
Repositioning sociocultural safety and security in shaping disabled-friendly urban spaces
Authors: Rudwiarti L A , Setiadi A , Mustaqim K F , Longa J M T
Published: June 2021

Sociocultural aspects are very critical in the daily life activities of people, including for the disabled, as their mobility limitation quite often cause a handicap for dependency. Disabled-friendly environment design becomes essential for their daily needs of behaviour and activities. This paper aims to investigate how sociocultural aspects guarantee the disabled’s safety and security in urban public spaces in Yogyakarta, Indonesia. It searches the conceptual framework of how do the disabled consume the urban public areas, and whether the ICT (Information Communication and Technology) sufficiently support a better solution for the environment. The methods for collecting data used behaviour setting, observation of the physical environment, interviews with interrelated actors in disabled-friendly design to test the results. The preliminary findings show that the use of ICT that psychologically represents the power of techno-socio-cultural network among society is a significant matter to support the solution.
Evaluating human-centered design methods as an approach for inclusive green design: Case study Kampung Kota Surakarta
Authors: Kusumaningdyah N H , Ratri W
Published: June 2021

Acceptable design by community is a significant indicator of success inclusive design and sustainable human settlement. There are many cases where programs initiated by the government to cope with specific issues or problems have failed to gather support from the community. The communities do not have a sense belonging to the design which leads to unsustainable program. The human design center (HCD) has been advocated as an approach for inclusive, participatory design in community programs. This study aims to investigate the key success of implementation of human centre design methods with Program Kampung Iklim (Proklim) Surakarta as a case study. Proklim is a national program to promote community actions to promote resilience to climate change impacts. Elaborating Human Center Design in the implementation of Proklim program in Surakarta city, the collaboration process in design is discussed, placing emphasis on how to include end-users in the development process. The study shows that the same method would not necessarily produce the same outcomes in different areas. Despite scant evidence of its effectiveness to produce acceptable design, The study reveals that four pre-conditions need to be established in using participatory design approach implemented in community programs, that are knowledgeable community leaders, informed communities, social bonding and community acceptance regarding the program. Thus, this is crucial for the government to take into consideration community leader regeneration as a regular agenda.
Green space as potential for forming a sustainable city
Authors: Safrilia A , Poerwoningsih D
Published: June 2021

The growing of development in Malang City, Indonesia has unwittingly brought an impact on changes in land use and exploitation of natural resources. With this development, it also affects the amount of Green Open Space. This study aims to determine how much benefit is obtained in increasing the area of green open space in Malang, given the importance of green space in improving the quality of the urban environment, as well as how architects implement components to support the creation of green open spaces that are safe, inclusive, and accessible. The method used is descriptive qualitative. The expected result is to be able to find out how much influence the amount of Green Open Space in Malang City and what components are needed in order to create a Green Open Space that is safe, inclusive, and accessible.
Study of indigenous village settings in Bali
Authors: Mandaka M , Sasmito A , Andadari T S
Published: June 2021

Traditional villages in Bali are traditional villages that are unique, especially in their settlement patterns which are integrated with local culture. Currently these settlements still exist and are well maintained. The research objective of the study of settlement patterns in traditional villages in Bali is to determine the settlement patterns of traditional villages in Bali, namely Panglipuran village, Tengahan village and Trunyan village as well as the effort factors that affect the sustainability of settlement patterns in Bali. The research method used is descriptive qualitative method by observing and studying literature. From the results of the study, it can be seen that the formation of the settlement patterns of the three traditional villages are (1) based on the history of settlement formation, (2) regional cosmology, (3) characteristics of house shapes and (4) kinship systems as well as several factors that affect the sustainability of traditional village settlement patterns. in Bali.
Livable floodplain settlement, force adaptation, or landform adaptation? (Case in Bengawan Solo river downstream)
Authors: Firsandy B A , Gunawan T , Kurniawan A , Prayitno B
Published: June 2021

The growth of settlements in the floodplain area downstream of Bengawan Solo has caused by conversion from agricultural to residential areas so that the growth of the settlements in this area have a high vulnerability to river floods. Mapping of Landsat results was carried out in residential areas affected by river floods and compiled with settlement tracing maps. Overlay results are analyzed by referring to the concept of building distance, building boundaries with rivers, building boundaries with roads. The results obtained are the pattern of adaptation of the settlements to the area that is the place of inundation, the tendency of adaptation based on function orientation, and physical orientation of the settlement pattern of floodplain downstream of the Bengawan Solo river.
The role of site development in sustainable city (Case study: Site of the noble house in Mega Kuningan, Jakarta)
Authors: Pribadi I G O S , Achadiat M P
Published: June 2021

The availability of open space has become increasingly limited. It is important to see how urban area is developed towards sustainability. At present, the completeness of infrastructure, urban networks, transportation, utilities, public and social facilities have been often developed to meet mostly commercial aspects related to human need without environmental consideration. This research aims to recognize the condition of site development in one case of office building in Jakarta through quality measurement using green building criteria. The green area of the site is the main aspect which become prerequisite for assessing the appropriate site development. In addition, site selection, community accessibility, and public transportation are also included as criteria for this study. The steps of this research can be generally implemented in many new building cases.