Flexible Ground Research Articles

UAV-enabled software defined data collection from an adaptive WSN

AbstractUnmanned aerial vehicle (UAV)-based data gathering from wireless sensor networks is one of the recent research topics that has currently attracted research interest. One of the challenges for the UAV-aided WSN data collection efforts is to design an energy-efficient UAV/drone communication with arbitrarily dispersed ground sensors by improving the ground network structure. This paper aims to develop a technique titled UAV Fuzzy Travel Path' that supports UAV smooth path design and enables ground network topology shifting. A comprehensive UAV-based data collection model is proposed to enable dynamic orchestration/re-orchestration of wireless ground sensors to jointly improve network performance and UAV path fluidity. This provides a more flexible ground network framework that can be restructured based on network demands and UAV optimal paths, effectively allowing for a software-defined network concept. The main contribution of this work is the implementation of the software-defined wireless sensor network on the ground network that adaptably supports the movement of the UAV and enhances the communication network’s energy efficiency with a proposed latency analytical analysis via network orchestration/re-orchestration phases. The main significance of this research is in offering a flexible span for UAV path design than being fixed in one strict route for data gathering purposes. Four various simulation tools are employed for modelling and performance evaluation, namely MATLAB, CupCarbon, Contiki-Cooja and Mission Planner. The proposed software-defined ground network system demonstrates encouraging results in terms of network performance metrics including energy consumption of UAV versus ground sensor nodes energy usage, packet delivery rate, and the communication time of the ground orchestrated or/and re-orchestrated network.

Seismic evaluation and reliability index of soft story buildings on flexible soils by using old and current seismic regulations in Mexico

A very important number of buildings with a flexible ground floor in Mexico City presented severe damages and collapses during the intraplate earthquake (Mw = 7.1) of September 19, 2017. The statistics of the damaged buildings showed that most of the collapsed structures were designed with a regulation in force in the late 70′s. As a response to the damages observed during this seismic event, the current version of the seismic regulation for Mexico City added a specific chapter for the analysis and design of structures with a flexible ground floor. This study assesses the seismic response of the existing buildings subjected to accelerograms recorded during the occurrence of this earthquake and the expected behavior of new structures designed with the current seismic regulations. To evaluate the methodology proposed in the code to design weak-story buildings, reliability indices of buildings designed with the regulation in force at the end of the 70′s and those obtained in buildings designed with the current regulation were determined. Soil-structure interaction played a very important role in the geographical distribution of the buildings with the greatest damage and also in areas that presented only slight damage. The soil-structure interaction was modeled as suggested in the current Mexican standards. The results show that the range of computed reliability indices in the structures built in the 70′s explain the collapses observed, and not in all cases, the current regulation leads to satisfactory values ​​of the reliability index, particularly when including the soil-structure interaction effects.

Fault location of flexible grounding distribution system based on multivariate modes and kurtosis calibration

Aiming at the problems of large fault location errors when the traditional traveling wave fault location is applied to flexible ground distribution systems. This paper proposed the fault location of flexible grounding distribution system based on multivariate modes and kurtosis calibration. Firstly, a disturbance signal is generated by putting a small resistor in parallel. This signal reaches the fault point and undergoes a sudden change, generating an aerial mode traveling wave signal. Secondly, it used the multivariate variational mode decomposition algorithm to decompose the aerial mode current and extracts the fault features. Then, the discrete kurtosis value is calculated for the highest frequency intrinsic mode function component. The moment of maximum kurtosis is the arrival time of the aerial mode current. Finally, it adopted the head-end detection device to calculate the fault distance. For the complex topology of the flexible ground distribution systems, the localization equation of the overhead line, cable line, and hybrid lines are studied, and the pseudo-fault points are excluded by adding auxiliary devices at the branch end. The simulation results demonstrate that the proposed method can accurately locate faults and is not affected by the fault's initial phase angle, transition resistance, and location.

Seismic response and reliability index of RC weak story buildings on soft soils of Mexico city

For more than 50 years, buildings with soft ground floors continue to suffer severe damage and collapse when subjected to seismic events. During the earthquakes of September 19, 1985 and 2017 that occurred in Mexico, a significant number of collapsed buildings had this type of structure. Currently, many existing buildings have a parking zone on the ground floor and apartments for residential use on the upper floors. The parking area is supported by columns and beams, whereas the slabs of the upper floors are supported by masonry walls, creating a weak story at the ground level. In order to explain the collapses of weak story buildings observed during the earthquake of September 19, 2017, this study evaluates the seismic response and determines the reliability indices of a typology of buildings with flexible ground floors in Mexico City. Additionally, passive control devices with friction energy dissipation, hysteric behavior and viscous dampers, were proposed to retrofit the buildings and increase the reliability indices of the structures. Results showed that the reliability indices of existing buildings with a weak ground floor are very low, which explains the observed damages and collapses during the 2017 earthquake. Reliability indices of the retrofitted buildings were significantly increased and the failure probabilities of the structures were strongly reduced, showing the effectiveness of passive control systems to mitigate the seismic risk of this type of structures.

Using the Data of Geocryological Monitoring and Geocryological Forecast for Risk Assessment and Adaptation to Climate Change

Permafrost monitoring should be organized in different ways within undisturbed landscapes and in areas with technogenic impacts. The state and dynamics of permafrost are described by special indicators. It helps to characterize seasonal and long-term tendencies and link them with permafrost hazards estimation. The risk is determined by the hazard probability and the vulnerability of infrastructure elements. The hazard does not have integral indicators, but is determined by separate spatial and temporal characteristics. The spatial characteristics include the ground’s physical and cryolithological features that are linked with the history of the permafrost. The temporal characteristics are associated with the future evolution of the climate and anthropogenic pressures. The geocryological monitoring content and geocryological forecasting are interdependent and should be implemented together. The adaptation recommendations are based on the analytical algorithms and use the results of permafrost monitoring and permafrost state forecasting. The development of an adaptation program is a recognition of the company’s responsibility for the sustainable development of resource management territories. Risk management uses the methods of the flexible ground temperature regime management.

Aggregation-Induced Emission: From Small Molecules to Polymers-Historical Background, Mechanisms and Photophysics.

The enhancement of photoluminescence through formation of molecular aggregates in organic oligomers and conjugated organic polymers is reviewed. A historical contextualization of aggregation-induced emission (AIE) phenomena is presented. This includes the loose bolt or free rotor effect and J-aggregation phenomena, and discusses their characteristic features, including structures and mechanisms. The basis of both effects is examined in key molecules, with a particular emphasis on the AIE effect occurring in conjugated organic polymers with a polythiophene (PT) skeleton with triphenylethylene (TPE) units. Rigidification of the excited state structure is one of the defining conditions required to obtain AIE, and thus, by changing from a flexible ground state to rigid (quinoidal-like) structures, oligo and PTs are among the most promising emerging molecules alongsidewith the more extensively used TPE derivatives. Molecular structures moving away from the domination of aggregation-caused quenching to AIE are presented. Future perspectives for the rational design of AIEgen structures are discussed.

Stress and stability analysis of slewing motion for crawler crane mounted on flexible ground

The ground deformation causes the increasing of crawler crane side loading, even leads to the boom stress failure or crane tipping failure during slewing motion. This paper established a flexible multibody dynamics simulation model considering the coupling effects of the crane mechanical structure flexibility, ground deformation, and load's dynamic pendulum motion. The model has been verified by analytical model based on Winkler foundation and experimental data. Then the simulation model has been further used to analyze the influence of different foundation modulus, slewing speeds, and lifting heights on the crane boom max stress and the tipping stability. The result offers the slewing speed threshold, which can prevent stress and tipping failures for the crawler crane mounted on flexible ground. The research provides reference for the design and safe operation of crawler cranes.

STUDY ON THE DYNAMIC NUMERICAL ANALYSIS METHOD FOR THE SETTLEMENT OF FLEXIBLE PAVEMENT

In view of the problems of a single parameter of rock and soil materials, unclear boundary simulation and a simplified dynamic load in the current calculation of pavement settlement, the stochastic finite element-infinite element coupling method was adopted in this study to simulate the roadbed of rock and soil, with a dynamic response analysis and a flex- ible pavement settlement calculation of roadbed were carried out under stochastic dynamic load. Discrete methods and dynamic stochastic finite element formulas for rock and soil random fields were particularly dealt with in this study. The results show that the method to stimulate roadbed is true with high calculation accuracy and strong engineering guiding significance. The displacement of flexible ground at any depth can be obtained by calculating the settlement of flexible pavement with the aid of the Matlab computer program.

Supporting Capacity-Building Project Characteristics Test of Zhoushan Multi-Terminal HVDC Flexible Demonstration Project

In this paper, a flexible Zhoushan multiterminal HVDC test demonstration projects supporting capacity-building project for the study, the DC cables through the flexible testing ground field measurements of its surrounding environment, the DC cables of a flexible environment affect the characteristics of the test site. The results show: the project on the surrounding environment has little effect of electromagnetic radiation, which affect the field strength generated by the project on the environment is negligible, the project generated frequency electric field, power frequency magnetic fields, DC magnetic field, radio interference strength, noise are smaller than the corresponding standard limits.

‘They all just want to get healthy!’ Drinking the Qur’an between forming religious and medical subjectivities in Zanzibar

This article investigates how the practice of drinking kombe (drinking washed off Qur’anic verses) informs subjectivities in the nexus of ‘religion’, ‘medicine’ and their Swahili approximations dini and dawa. Situated in Zanzibar, it is mostly referred to as dawa ya kiislamu, bringing ‘medicine’ and ‘religion’ together and providing space for multiple enactments of subjectivities. Most prominently, Christians’ use of kombe requests a different engagement with kombe and accentuates the ambiguity of drinking kombe as an embodiment of Islamic scripture conveyed by Islamic connotations of the Qur’an that heals, on the one hand, and drinking kombe as treatment irrespective of ‘religious’ affiliation, on the other. This becomes particularly pertinent in the discourse justifying drinking the Qur’an against anticipated criticism. These justifications enable the practice of drinking kombe to reveal different implications for the formation and cultivation of subjectivities with respect to the flexible ground of enacting dawa ya kiislamu.

The effect of boundary conditions, model size and damping models in the finite element modelling of a moving load on a track/ground system

An investigation is presented of the use of finite element models in the time domain to represent a load moving on a railway track on a flexible ground. A systematic study is carried out to compare different sizes and shapes of finite element mesh, different boundary conditions intended for suppressing reflections from the truncated model boundaries, and different models of soil damping. The purpose is to develop guidance to assist in selecting appropriate finite element models for moving load problems. To prevent reflections from the boundaries of the finite domain two approaches are compared. A 40m radius hemispherical finite element mesh has been used first with infinite elements around the perimeter. This approach gives good results for a point harmonic load at the centre of the domain but some problems are highlighted when it is used for moving load calculations. An alternative approach has therefore been investigated based on a cuboid mesh. The base was fixed to prevent rigid-body motions of the model and, rather than use infinite elements at the sides, these were also fixed. It is shown that, provided that a suitable damping model is used, the spurious reflections from the sides of the model can be suppressed if the model is wide enough. On the other hand, if infinite elements are used, the calculations are found to be considerably more costly with little added benefit. Different models of soil damping are also compared. It is shown that a mass-proportional damping model gives a decay with distance that is independent of frequency, making it particularly suitable for this application. The length of model required to achieve steady state has been investigated. For a homogeneous half-space it is found that the required length increases considerably in the vicinity of the critical speed, up to 130m in the present example, whereas for the layered ground a more modest length is sufficient for all speeds.

Closed-Form Critical Earthquake Response of Elastic–Plastic Structures on Compliant Ground under Near-Fault Ground Motions

The double impulse is introduced as a substitute of the fling-step near-fault ground motion. A closed-form solution of the elastic-plastic response of a structure on compliant (flexible) ground by the ‘critical double impulse’ is derived for the first time based on the solution for the corresponding structure with fixed base. As in the case of fixed-base model, only the free-vibration appears under such double impulse and the energy approach plays an important role in the derivation of the closed-form solution of a complicated elastic-plastic response on compliant ground. It is remarkable that no iteration is needed in the derivation of the critical elastic-plastic response. It is shown via the closed-form expression that, in the case of a smaller input level of double impulse to the structural strength, as the ground stiffness becomes larger, the maximum plastic deformation becomes larger. On the other hand, in the case of a larger input level of double impulse to the structural strength, as the ground stiffness becomes smaller, the maximum plastic deformation becomes larger. The criticality and validity of the proposed theory are investigated through the comparison with the response analysis to the corresponding one-cycle sinusoidal input as a representative of the fling-step near-fault ground motion. The applicability of the proposed theory to actual recorded pulse-type ground motions is also discussed.

Perfectly matched discrete layers for three-dimensional nonlinear soil–structure interaction analysis

The dynamic behavior of structures established in flexible ground can be greatly influenced by soil–structure interaction. The challenge with regard to soil–structure interaction is to model the nonlinear behavior of soil in the vicinity of the foundation, including the boundary nonlinearity at the interface and the radiation of energy into infinity simultaneously. In this study, a three-dimensional time-domain formulation of perfectly matched discrete layers (PMDLs) is developed. It can be combined with a detailed finite-element model of the near-field region surrounding the foundation. The developed PMDL formulation can minimize the modeling region. A procedure to determine the parameters of the three-dimensional PMDLs to model a layered half-space effectively and accurately is proposed. Green’s functions are calculated in half-spaces with the developed method and found to agree well with existing solutions. The developed PMDL formulation is applied to a nonlinear three-dimensional soil–structure interaction analysis, confirming its capability.

Seismic Response of Rocking Oscillators on a Soft Story: Elastic Response

AbstractThe elastic response of a class of nonlinear oscillators that represent structural systems with a relatively rigid superstructure on a soft ground story is evaluated under lateral base excitation. The governing equations of motion are developed, accounting for both lateral translation and overturning rocking of the rigid superstructure relative to the flexible ground story. In this work, the system parameters are identified initially for linear elastic response and, subsequently, in a companion publication, for the case of the base exhibiting nonlinear resistance–deformation characteristics. The dynamic coupling between lateral and rocking modes is evaluated under a base excitation for different system period and resistance parameters, and the deformation and force demands are compared with the single-degree-of-freedom lateral-response-only predictions, as typically considered in seismic design. It is shown that the presence of rocking of the rigid superstructure causes an increase in the transver...

The effect of flexibility in ground storey of concrete walls and infilled frames on their seismic response

By using a previously developed numerical model of the authors for both static and dynamic analysis of plane reinforced concrete and masonry structures that can simulate their main nonlinear effects, the influence of flexibility in ground storey of concrete walls and infilled reinforced concrete frames on their behavior under earthquakes has been researched. Single three‐storey reinforced concrete walls and single three‐storey reinforced concrete frames were analyzed, each for the case of the equal rigidity through all floors and for the case with flexible ground storey. Frames with strong and weak infilled masonry were considered. Five different earthquakes were applied, that cause high structural nonlinearity. It is assumed that foundations are supported by a rigid base, with the possibility of lifting. Typical displacements, inertial forces, stresses and damage zones of the analyzed structures are presented. Finally, main conclusions and recommendations for practical application are given.

High-Performance Interface Electronic System for a 13$\,\times\,$13 Flexible Biomechanical Ground Reaction Sensor Array Achieving a Gait Ground Velocity Resolution of 100 $\mu{\rm m/sec}$

This paper describes a high-performance interface electronics system design for a high-density flexible biomechanical ground reaction sensor array (GRSA). The prototype system can be incorporated into a personal boot heel to measure real-time ground force, shear strain, and sole deformation associated with a human bipedal locomotion, thus providing zero-velocity correction to an inertial measurement unit placed in a close proximity. This approach can greatly reduce inertial error accumulation and improve positioning accuracy. The sensing electronics consist of a front-end multiplexer that can sequentially connect individual sensing nodes from a 13 × 13 GRSA to a capacitance-to-voltage converter followed by a 12-bit algorithmic ADC with a sampling rate of 66.7 k-samples/s. The entire sensor array can be scanned within 10 ms. The GRSA employs capacitive sensing scheme and is fabricated using PDMS deformable dielectric layer. The integrated sensing electronics are fabricated in XFAB 0.35 μm CMOS process and dissipate 3 mW power. The overall system sensing resolution is limited by electrical interferences coupled through long interconnect traces between a GRSA and an electronic sensing module. Dynamic and static pressure testing shows the prototype system functionality achieving a gait ground velocity sensing resolution of 100 μm/s.

Wing/kite-based wind energy generation: An overview

Several technologies, aimed at converting high-altitude wind into electricity, are actually being investigated by companies, research centers and universities worldwide, and the community of people working in this field has coined the term airborne wind energy (AWE) as a common umbrella for these concepts. Indeed, many basic ideas that are now being developed in the context of AWE were already present in patents and publications since the ’70s. Then, these ideas remained somehow silent, until more recent years, when several research groups and companies started to carry out theoretical, numerical and experimental analyses, made possible by important advances in diverse fields like materials, aerodynamics, sensors, computation and control. In this lecture, the basic AWE concepts and results that have been up to date accomplished are overviewed, with a focus on a particular class of AWE generators, namely with flexible wings and ground level generators, and emphasis on optimization and control aspects. Finally, we delineate what challenges are still to be faced, in order to fully demonstrate the viability of airborne wind energy.

Escaping death: single-patterning contact printing for <inline-formula><math display="inline" overflow="scroll"><mrow><mn mathvariant="bold">32</mn><mo mathvariant="bold">/</mo><mn mathvariant="bold">28</mn></mrow></math></inline-formula>-nm logic technology nodes

As 193-nm immersion lithography is extended indefinitely to sustain technology roadmaps, there is increasing pressure to contain escalating lithography costs by identifying patterning solutions that can minimize the use of multiple-pass processes. Contact patterning for the 32/28-nm technology nodes has been greatly facilitated by the just-in-time introduction of new process enablers that allow the support of flexible foundry-oriented ground rules alongside high-performance technology, without inhibiting migration to a single-pass patterning process. The incorporation of device-based performance metrics, along with rigorous patterning and structural variability studies, was critical in the evaluation of material innovation for improved resolution and CD shrink. Additionally, novel design changes for single patterning incorporating mask optimization efforts, along with new capability in data preparation, were assessed to allow for minimal impact of implementation of a single patterning contact process late in the 32-nm and 28-nm development cycles. In summary, this paper provides a comprehensive study of what it takes to turn a contact-level double-patterning process into a single-patterning process consisting of design and data manipulation, as well as wafer manufacturing aspects, together with many results.

Modeling and Simulation of Passive Vibration Isolation System of Combustion Engine with Flexible Base

Based on multi-body dynamics, finite element method and solid modeling technology, a dynamic model combined rigid bodies and flexible bodies about passive vibration isolation system of combustion engine with flexible base was built. A simulation analysis was done for a passive vibration isolation system of four-cylinder diesel supported on a flexible flat plate. Simulation result showed static balance and exciting force were same with theory calculation. Through changing support stiffness between flexible flat plate and ground, boundary condition of flexible base could be changed. And the characteristics of vibration isolation were obtained when combustion engine’s flexible base had different stiffness. Compared bearing force of vibration isolator on flexible base with bearing force on rigid base, the results could be gotten that flexible base had important influence to bearing force of vibration isolator and free vibration influenced by base’s flexibility might become main factor to influence change of vibration isolator’s bearing force.

Calculation of Settlement of Composite Foundation with Rigid Piles under Flexible Ground

According to the character of the interaction of the pile, soil and cushion in composite foundation by fitting the vertical relative displacement distribution function of pile-soil element and introducing an elastic-plastic load transfer model, and deformation form of the pile-soil relative displacement, friction variation of pile, and pile-side soil reaction force model were simplified to a certain degree, and a basic differential equation of settlement calculation of the rigid pile composite foundation was established with consideration of both upward and downward penetration displacements of piles and the coordination of deformation of neutral point and the pile-soil interface. Then, a new method of calculating the settlement of the rigid pile composite foundation considering the interaction of pile-soil-cushion system was developed. At last, this new method was applied to the analysis of a model experiment and a project example, and the results show that (1) there exist great difference between the deformation mode and pile-soil stress ratio of rigid pile composite foundation under flexible ground and those under rigid ground; (2) the calculated results are close to the measured values. This method can reduce the calculation and provide a reference for the settlement calculation of rigid pile composite foundation.