Flat Platform Research Articles

A flat management platform based on mobile internet

A flat management platform based on mobile internet

Application of Tiling Theory for Path Planning Strategy in a Polyiamond Inspired Reconfigurable Robot

Commercial floor cleaning robots face significant challenges in accessing convex and narrow corners due to their fixed and regular morphologies. To overcome this, we develop a new class of self-reconfigurable floor cleaning robot, hTetrakis, which is composed of tetriamonds (four equilateral triangles aligned along the edges) that adopt three distinct forms (“I”, “A”, and “U” shapes). When on a flat and rigid platform, these forms have convex corners that help to cover narrow regions. This paper addresses the mechanical structural design, reconfiguration of the robot platform through the hinge mechanism, and the electronics and navigation module of hTetrakis. Based on finite element studies, we estimate the system’s natural frequency, stress, and deformation patterns developed in the structural components of the robot, and validate the proposed design to overcome structural failure and system resonance. In order to achieve maximum area coverage using the tetriamond forms, we formulate tiling theorems and apply them for path-planning techniques during the floor cleaning process. By using a robot prototype, we conduct experiments to validate the proposed tiling theorem based on the percentage of area coverage, and demonstrate that this platform is able to cover the floor area efficiently.

Influence of some environmental factors on growth of gray sea urchin (Strongylocentrotus intermedius) at the northwestern coast of the Japan Sea

Habitat conditions, as qualitative and quantitative composition of aquatic vegetation and oceanographic factors, are compared for six populations of sea urchinStrongylocentrotus intermediuswith different growth rate and mean size of individuals. The highest growth rate is observed in the areas between Cape Sosunov and Plitniak Bay, between Oprichnik Bay and Cape Grozny, and between Cape Lisuchenko and Kreiser Rock Island; all these areas are distinguished by high density and species diversity of macrophytes. On the contrary, the growth rate is the lowest at Cape Yuzhny where the vegetation is less abundant. All populations of slow-growing sea urchins inhabit the areas exposed to wave action that usually forms flat rocky platforms: at Cape Yuzhny, at Cape Nadezhda, and between the Yezhovaya Bay and Cape Khitrovo. However, density of sea urchin populations in these areas is higher (on average from 9.8 to 20.8 ind./m2) than in the areas with relatively high growth rate (from 0.16 to 7.20 ind./m2). Any signifcant correlation between the water temperature and mean size of sea urchins, by ages, is not detected.

Adaptive gait generation for humanoid robot using evolutionary neural model optimized with modified differential evolution technique

Abstract Gait generation plays a decisive role to the performance of biped robot walking. Under mathematical viewpoint, the task of gait generation design is investigated as an optimization problem with respect to various trade-off constraints, hence it prefers to evolutionary computation techniques. This paper introduces a novel approach for the biped robot gait generation which aims to enable humanoid robot to walk more naturally and stably on flat platform. The proposed modified differential evolution (MDE) optimisation algorithm is initiatively applied to optimally identify the novel adaptive evolutionary neural model (AENM) for a dynamic biped gait generator. The performance of proposed MDE method is demonstrated in comparison with other genetic algorithm (GA) and particle swarm optimisation (PSO) approaches. The proposed method is implemented and tested on a prototype small-sized humanoid robot. The identification result demonstrates that the new proposed neural AENM model proves an effective approach for a robust and precise biped gait generation.

Real-time modeling and parameter approximation of dexterous garment folding by robot

One of the challenging tasks for general household robot of doing household work is to manipulate deformable objects such as garments. The improper folding procedure by the robot will cause the failures such as generating wrinkles, cause the garment to misalign and the following folding process will possibly fail. Moreover, given different types and sizes of garment, the robot should able to understand its perception and planning strategy such as the start and end position of grasping points, the trajectory for each sequence and also the completed folding procedure. This paper present a novel generic approach of real-time modeling and parameter approximation applied in the dexterous robotic manipulation of unknown garment using particle-based polygonal model with online simulation. The proposed approach is a system that can judge which of the prepared polygonal models is appropriate. The prepared model is used to simulate a crudely spread-out garment placed on the flat platform that can be recognized by vision sensor. The parameters of the garment can be approximated from the proposed model and then the folding procedure can be planned based on these parameters. Later, the robot can follow the trajectory from simulation to achieve the acceptable result in the real garment folding.

Does Chronic Ankle Instability Influence Knee Biomechanics of Females during Inverted Surface Landings?

The primary purpose of the study was to determine whether atypical knee biomechanics are exhibited during landing on an inverted surface. A seven-camera motion analysis system and two force plates were used to collect lower extremity biomechanics from two groups of female participants: 21 subjects with chronic ankle instability (CAI) and 21 with pair-matched controls. Subjects performed ten landings onto inverted and flat platforms on the CAI/matched and non-test limbs, respectively. Knee and ankle joint angles, joint angular displacements, joint moments and eccentric work were calculated during the landing phase and/or at the initial contact. Paired t-tests were used to compare between-group differences (p<0.05). We observed that CAI group displayed a significantly increased knee flexion angle, knee flexion displacement, peak knee extension moment and internal rotation moment, and eccentric work in the sagittal plane, possibly due to altered ankle biomechanics. Participants with CAI employed some compensatory strategy to improve their ankle and postural stability during landing onto the tilted surface. The increased knee extension and internal rotation moments of CAI participants could potentially result in a greater ACL loading. In future studies, it may be worthwhile to measure or estimate the ACL loading to confirm whether CAI could relate to the mechanism of ACL injury.

The lacustrine microbial carbonate factory of the successive Lake Bonneville and Great Salt Lake, Utah, USA

AbstractThe Bonneville Basin is a continental lacustrine system accommodating extensive microbial carbonate deposits corresponding to two distinct phases: the deep Lake Bonneville (30 000 to 11 500 14C bp) and the shallow Great Salt Lake (since 11 500 14C bp). A characterization of these microbial deposits and their associated sediments provides insights into their spatio‐temporal distribution patterns. The Bonneville phase preferentially displays vertical distribution of the microbial deposits resulting from high‐amplitude lake level variations. Due to the basin physiography, the microbial deposits were restricted to a narrow shoreline belt following Bonneville lake level variations. Carbonate production was more efficient during intervals of relative lake level stability as recorded by the formation of successive terraces. In contrast, the Great Salt Lake microbial deposits showed a great lateral distribution, linked to the modern flat bottom configuration. A low vertical distribution of the microbial deposits was the result of the shallow water depth combined with a low amplitude of lake level fluctuations. These younger microbial deposits display a higher diversity of fabrics and sizes. They are distributed along an extensive ‘shore to lake’ transect on a flat platform in relation to local and progressive accommodation space changes. Microbial deposits are temporally discontinuous throughout the lake history showing longer hiatuses during the Bonneville phase. The main parameters controlling the rate of carbonate production are related to the interaction between physical (kinetics of the mineral precipitation, lake water temperature and runoff), chemical (Ca2+, Mg2+ and HCO3− concentrations, Mg/Ca ratio, dilution and depletion) and/or biological (trophic) factors. The contrast in evolution of Lake Bonneville and Great Salt Lake microbial deposits during their lacustrine history leads to discussions on major chemical and climatic changes during this interval as well as the role of physiography. Furthermore, it provides novel insights into the composition, structure and formation of microbialite‐rich carbonate deposits under freshwater and hypersaline conditions.

High‐Efficiency Metasurfaces: Principles, Realizations, and Applications

AbstractMetasurfaces are planar metamaterials exhibiting certain inhomogeneous phase distributions for transmitted or reflected waves, which can efficiently reshape the wave‐fronts of incident beams in desired manners based on the Huygens principle. Due to their exotic abilities to freely manipulate electromagnetic (EM) waves on a flat and ultrathin platform, metasurfaces have attracted intensive attention recently, resulting in numerous new concepts and effects that could possibly find applications in many different aspects. In this article, the key achievements in this field are briefly summarized, with focus put on the efficiency issue of metasurfaces. After introducing the basic concept of metasurfaces and their early realizations, successively the mechanisms and realizations of high‐efficiency metasurfaces are described: for manipulating linearly polarized EM waves in reflection and transmission geometries, and for manipulating circularly polarized EM waves based on the geometric‐phase concept, using plasmonic materials as well as dielectric ones. Then, several important applications of high‐efficiency metasurfaces are summarized, including polarization control, metaholograms, metalenses, and surface wave couplers. Finally, this review is concluded with personal perspectives on the future directions of this rapidly growing research field.

Sedimentation adjacent to atolls and volcano-cored carbonate platforms in the Mozambique Channel (SW Indian Ocean)

Recently acquired data from the Iles Eparses (southwestern Indian Ocean) reveal new information about the geomorphology, depositional processes, and sedimentary deposits on the slopes of atolls and atoll-like platforms. The deposits discussed here lie on the deepwater flanks of isolated, inactive volcanos that are capped by shallow, relatively flat carbonate platforms 45–210 km2 in area. Much of the slope geomorphology is controlled by the underlying volcanic edifice. Steep (~25–35°) upper slopes consist of outcrops of volcanic basement, smooth banks, failure scarps, and channels. Sedimentary features seen in the lower slope and proximal basin (2000–3500 m deep) consist of channels, levees, lobes, and mass transport deposits (MTDs). In places, channels terminate 13–18 km from the platform margin, ending in lobes up to 3.5 km across, a feature not often seen in modern carbonates. In the subsurface, MTDs are present near all platforms. Within MTDs, seismic character is variable, often consists of chaotic reflections indicative of sediment gravity flow processes. Subsurface units with organized (retro- or progradational) reflections are interpreted as turbidite lobes or MTDs with compressional features. Core taken within lobes and near the base of slopes reveal decimeter-scale turbidites and debrites composed primarily of graded and massive bioclastic grainstones and packstones with abundant neritic skeletal components, interbedded with hemipelagic aragonitic and clay-rich foraminiferal ooze. Slope depositional processes are therefore primarily gravity-driven and occur at different scales; i.e., bed-scale turbidites and muds may be remobilized and redeposited through slope failure and deposition of large MTDs. Dominant wind direction may also play a role in slope sedimentation: leeward slopes are generally less rugose and show increased sedimentation at the toe of the slope. This study thus provides new insight into depositional systems surrounding atoll-like carbonate platforms, and provides a new analogue for similar deposits in the geologic record.

Facile synthesis of one-dimensional hollow Sb2O3@TiO2 composites as anode materials for lithium ion batteries

Metallic Sb is deemed as a promising anode material for lithium ion batteries (LIBs) due to its flat voltage platform and high security. Nevertheless, the limited capacity restricts its large-scale application. Therefore, a simple and effective method to explore novel antimony trioxide with high capacity used as anode material for LIBs is imperative. In this work, we report a facile and efficient strategy to fabricate 1D hollow Sb2O3@TiO2 composites by using the Kirkendall effect. When used as an anode material for LIBs, the optimal Sb2O3@TiO2 composite displays a high reversible discharge capacity of 593 mAh g−1 at a current density of 100 mA g−1 after 100 cycles and a relatively superior discharge capacity of 439 mAh g−1 at a current density of 500 mA g−1 even after 600 cycles. In addition, a reversible discharge capacity of 334 mAh g−1 can also be obtained even at a current density of 2000 mA g−1. The excellent cycling stability and rate performance of the Sb2O3@TiO2 composite can be attributed to the synergistic effect of TiO2 shell and hollow structure of Sb2O3, both of which can effectively buffer the volume expansion and maintain the integrity of the electrode during the repeated charge-discharge cycles.

Do depressive symptoms affect balance in older adults with mild cognitive impairment? Results from the “gait and brain study”

Background: Mild cognitive impairment (MCI) and depression independently affect balance control in older adults. However, it is uncertain whether depressive symptoms would amplify balance problems in older adults with MCI.Aim: To evaluate if the presence of significant depressive symptoms affects postural sway under somatosensory challenges in a MCI population.Methods: Eighty two participants (mean of 75.3 ± 6.4 years of age; 46% women) with MCI completed cognitive and balance assessments. Participants were grouped by severity of depressive symptoms using the Geriatric Depression Scale-15, as MCI with depressive symptoms (MCI-D = 14, score ≥ 5) and MCI without depressive symptoms (MCI = 68, score < 5). Postural sway area was evaluated during eyes open (EO) and eyes closed (EC) while standing on a rigid flat force plate platform, and compared across groups. Analyses were controlled for age, sex, comorbidities, anti-depressant medication use, executive function, and baseline sway.Results: MCI-D showed larger postural sway area when compared with MCI irrespective of visual feedback conditions (p = 0.03). This difference remained significant after adjusting for anti-depressant use and executive function performance. The lack of interaction between groups and visual condition was associated with group differences in postural sway during EO condition (Beta = 0.08, CI −257.5–621.9; p = 0.41) and by comparable sway increase from EO to EC in both groups.Conclusion: Depressive symptoms in individuals with MCI worsened postural stability during both eyes open and eyes closed conditions independently of cognitive function. Significant depressive symptoms may affect balance in MCI populations, potentially increasing the risk of falls.

The emergence and significance of heavy-duty scrapers in ancient stone toolkits

Heavy-duty scrapers are documented as a specific morphotype in ancient African and Eurasian toolkits from the Oldowan into the Acheulian. They are characterized by a flat platform perpendicularly oriented to a carinated edge. The convex surface of that edge displays semi-peripheral, unidirectional removals associated with steep retouch and/or crush marks. This morphotype has been described from numerous sites covering a long temporal scale and are diversely referred to in French as “rostro-carénés” or “nucléus-racloirs” and in English as “massive scrapers”, “core scrapers”, “large scrapers”, or “heavy end-scrapers”. Morpho-technological definitions and interpretations are reviewed to track the origin and evolution of heavy-duty scrapers over time and space. Results show that tools referred to as heavy-duty scrapers were made on thick cobbles during the Oldowan, and later, at the onset of the Acheulian, on Large Flakes, while smaller-sized items in Late Acheulian sites assume end-scraper morphologies. But should all of these tools really be grouped under a single denomination? Experimental work explores whether heavy-duty scrapers are the result of knapping processes, or if their morphology could be derived from other kinds of activities. Chronological continuity of the attributes specific to heavy-duty scrapers points to their role in ancient toolkits, suggesting that these scarce but ubiquitous primitive implements are, on equal footing with chopper-cores, one of the oldest morphotypes in the world.

The Role of Bed Roughness in Wave Transformation Across Sloping Rock Shore Platforms

AbstractWe present for the first time observations and model simulations of wave transformation across sloping (Type A) rock shore platforms. Pressure measurements of the water surface elevation using up to 15 sensors across five rock platforms with contrasting roughness, gradient, and wave climate represent the most extensive collected, both in terms of the range of environmental conditions, and the temporal and spatial resolution. Platforms are shown to dissipate both incident and infragravity wave energy as skewness and asymmetry develop and, in line with previous studies, surf zone wave heights are saturated and strongly tidally modulated. Overall, the observed properties of the waves and formulations derived from sandy beaches do not highlight any systematic interplatform variation, in spite of significant differences in platform roughness, suggesting that friction can be neglected when studying short wave transformation. Optimization of a numerical wave transformation model shows that the wave breaker criterion falls between the range of values reported for flat sandy beaches and those of steep coral fore reefs. However, the optimized drag coefficient shows significant scatter for the roughest sites and an alternative empirical drag model, based on the platform roughness, does not improve model performance. Thus, model results indicate that the parameterization of frictional drag using the bottom roughness length‐scale may be inappropriate for the roughest platforms. Based on these results, we examine the balance of wave breaking to frictional dissipation for rock platforms and find that friction is only significant for very rough, flat platforms during small wave conditions outside the surf zone.

Postural Training using Augmented Visual Feedback and Vestibular Activation in Healthy Adults

Postural Training using Augmented Visual Feedback and Vestibular Activation in Healthy Adults

Cell-Based Microarrays Using Superhydrophobic Platforms Patterned with Wettable Regions.

The use of patterned platforms to print cellular arrays enables the high-throughput study of cell behavior under a multitude of different conditions. This rapid, cost-saving and systematic way of acquiring biologically relevant information has found application in diverse scientific and industrial fields. In an initial stage of development, platforms targeting high-throughput cellular studies were restricted to standard two-dimensional (2D) setups. The design of novel platforms compatible with three-dimensional (3D) cell culture arose after the elucidation of the extreme importance of culturing cells in matrices resembling the native extracellular matrix-cells and cell-cell interactions. This need for biomimetic environments has been established in fields like drug discovery and testing, disease model development, and regenerative medicine. Here, we provide a description of the processing of flat platforms based on wettability contrast, compatible with the high-throughput generation and study of cell response in 3D biomaterials, including cell-laden hydrogels and porous 3D scaffolds. The application of the aforementioned platforms to produce 3D microtissues, which may find application as tissue models for drug screening or as biomimetic building blocks for tissue engineering, is also addressed. In this chapter, a description of the steps for (1) high-throughput platform processing, (2) deposition of cell and biomaterial arrays, and (3) image-based results screening is provided.

Fabrication and assessment of an electrospun polymeric microfiber-based platform under bulk flow conditions with rapid and efficient antigen capture.

This study investigated the fabrication and proof of concept design demonstrating rapid and highly sensitive antigen capture utilizing electrospun polystyrene (PS) microfiber mat substrates paired with vacuum pump pressurization to induce bulk flow. In comparison with conventional flat PS surfaces used for immunoassay purposes, this system optimizes the increased surface area of the electrospun polystyrene (ESPS) fiber mat substrates and the accelerated propagation of the antigen through the detection platform by using a vacuum pump to enable efficient and rapid antigen capture. The novelty of this work was demonstrated through a parametric study detailing how a fiber substrate can capture antigen sensitively and at high speeds. In terms of sensitivity, the current system is comparable to the conventionally used flat PS substrates. Additionally, the amount of antigen captured on a flat PS substrate in 60 minutes was surpassed in under 5 seconds when utilizing the ESPS-vacuum system. Three-dimensional ESPS fiber mats were then noted as a comparison between Damkohler numbers and between flat PS and ESPS-vacuum systems. The bulk flow of the ESPS-vacuum system allows for a Damkohler number of 0.37 indicating a balance between the flow rate and the reaction rate as opposed to a PS flat platform of 5.80 × 104 which illustrates a diffusion rate limited system. Finally, the overall ESPS-vacuum system was tested for its immunoassay capability. A sandwich fluorescence-based immunoassay was performed on both PS flat-diffusion and ESPS-vacuum systems. The ESPS-vacuum system indicated a wider detection range capability from 5 to 1000 ng mL-1 in comparison with the PS flat-diffusion system at 5 to 100 ng mL-1.

Controlled growth and optical response of a semi-hollow plasmonic nanocavity and ultrathin sulfide nanosheets on Au/Ag platelets.

Herein, we report a strategy to construct a semi-hollow plasmonic nanocavity and grow ultrathin sulfide nanosheets inside. The competition and cooperation of Au deposition with Ag etching based on flat Ag nanoplates are proposed. For the establishment of the semi-hollow nanocavity, Au shells are grown on Ag nanoplates, which serve as a stable frame, followed by partial etching of the Ag nanoplates. By controlling the thickness of the initial Ag nanoplates or the injected amount of etchant, the nanocavity size is fine-tuned. Significantly, the remaining unetched Ag layers provide a flat platform for the growth of 2D ultrathin sulfides of Ag2S and CdS inside the semi-hollow plasmonic nanocavity. Strong plasmon resonance and large local field enhancement are exhibited inside the plasmonic cavity where the ultrathin semiconductor sulfides are grown, indicating strong plasmon-exciton interactions in the hybrids. Furthermore, this synthetic approach is extended to grow other metal sulfides such as Bi2S3 and PbS. The combination of a flat plasmonic cavity with ultrathin semiconductor nanosheets in this study provides a new strategy for the development of unique plasmon-based hybrids with excellent optical properties.

The World’s Oldest Bridges - Mycenaean Bridges

The ancient bridges and their remnants located in the vicinity of and Arkadico villages are considered to be the world's oldest bridges. The bridges were built with massive irregular limestone blocks, called Cyclopean boulders, in the Bronze Age. Two of the four objects discussed here are still in operation, occasionally used for the needs of local agriculture. The bridges are classified as clapper schemes, but a lot points to the parallel use of the arch bridge technology. The remnants of the bridge in the vicinity of the modern , due to the significant width of the riverbed, suggest that it might have been the longest among Mycenaean bridges. Probably, it was a multi-span bridge. The structures of the discussed bridges have flat bottom platforms that stabilize the walls of the bridge openings and protect them against washing out. The technological problem of the bridge keystone installation was investigated in the cases of corbel and arch systems.

Long term analysis of bone stability around platform switched implants: a radiologic analysis of flat platform implants

Long term analysis of bone stability around platform switched implants: a radiologic analysis of flat platform implants

Optimization-based Dielectric Metasurfaces for Angle-Selective Multifunctional Beam Deflection

Synthesization of multiple functionalities over a flat metasurface platform offers a promising approach to achieving integrated photonic devices with minimized footprint. Metasurfaces capable of diverse wavefront shaping according to wavelengths and polarizations have been demonstrated. Here we propose a class of angle-selective metasurfaces, over which beams are reflected following different and independent phase gradients in the light of the beam direction. Such powerful feature is achieved by leveraging the local phase modulation and the non-local lattice diffraction via inverse scattered field and geometry optimization in a monolayer dielectric grating, whereas most of the previous designs utilize the local phase modulation only and operate optimally for a specific angle. Beam combiner/splitter and independent multibeam deflections with up to 4 incident angles are numerically demonstrated respectively at the wavelength of 700 nm. The deflection efficiency is around 45% due to the material loss and the compromise of multi-angle responses. Flexibility of the approach is further validated by additional designs of angle-switchable metagratings as splitter/reflector and transparent/opaque mirror. The proposed designs hold great potential for increasing information density of compact optical components from the degree of freedom of angle.