Passive Load Research Articles

Influence of Surcharge Load on the Adjacent Pile Foundation in Coastal Floodplain

In this paper, in order to investigate the behavior of existing piles caused by the horizontal and compression deformation of soft substratum due to backfill surcharge on coastal floodplain, three-dimensional finite element models of piles adjacent to surcharge load were established. The deformation and migration law of soft soil was analyzed. The behavior of single pile and double row pile adjacent to surcharge load were studied, in which the influence of surcharge load location, surcharge pressure, pile stiffness, and pile top constraint conditions were considered. The results show that as the position of surcharge load is closer and the surcharge pressure increases, the response (e.g. deformation and bending moment) is more obvious. With the increase of pile stiffness, the range of passive load is increased. The deformation behavior of pile body under different constraints of pile cap is significantly different. The effect of secondary bending moment caused by pile axial force is obvious and cannot be ignored. If there is a thick soft substratum, it is beneficial to improve the behavior of adjacent piles by using cement mixing pile reinforcement.

Performance of Permanent Magnet Synchronous Generator for Urban Water Pipeline Energy Harvester Considering Slotting and Load Effect on Radial Force Characteristic

This article proposes a 65 kW rim-driven direct-drive flux concentrated permanent magnet synchronous generator (FCPMSG) used in urban water pipeline energy harvester (UWEH) system. The proposed UWEH system plans to use hydraulic bearing; thus, a balanced radial force topology should be selected with high electromagnetic performance. Considering the hydraulic bearing mechanism and the installation of the proposed PM synchronous generator (PMSG), the effect of the loading and slot harmonics on the radial magnetic forces is analyzed. Furthermore, by studying the effect of the passive and active electric loads on the PMSGs, radial force characteristics are analyzed to select the operation region.

Making an Effort Versus Experiencing Load

In cognitive load theory (CLT), the role of different types of cognitive load is still under debate. Intrinsic cognitive load (ICL) and germane cognitive load (GCL) are assumed to be highly interlinked but provide different perspectives. While ICL mirrors the externally given task affordances which learners experience passively, germane resources are invested by the learner actively. Extraneous affordances (ECL) are also experienced passively. The distinction of passively experienced load and actively invested resources was inspired by an investigation where we found differential effects of a learning strategy training, which in fact resulted in reduced passive load and increased actively invested effort. This distinction is also mirrored in the active and passive forms for effort in German language: “es war anstrengend” (it has been strenuous) vs. “ich habe mich angestrengt” (I exerted myself). In two studies, we analyzed whether we could distinguish between these active and passive aspects of load by using these phrases and how this distinction relates to the three-partite concept of CLT. In two instructional design studies, we included the active and passive items into a differentiated cognitive load questionnaire. We found the factor structure to be stable, with the passive item loading on the ICL factor and the active item loading on the GCL factor. We conclude that it is possible to distinguish between active and passive aspects of load and that further research on this topic could be constructive, especially for learning tasks where learners act in a more self-regulated way and learner characteristics are taken into account.

Data-Driven Passivity-Based Control Design for Modular DC Microgrids

This article contains a new passivity-based control design approach for dc microgrids. The design is purely based on experimental data—bypassing the requirement of the network modeling. This approach permits the control of dc microgrids and preserve stability, despite of further interconnection of new passive loads and new passivity-based-controlled converters. This model-free approach generates control laws in a pure numerical way; bypassing the requirement of dealing with a high number of variables and equations that naturally appear in an increasingly complex dc microgrid. Experimental results are presented to corroborate the advantages of our approach.

A novel current amplitude differential protection for active distribution network considering the source-effect of IM-type unmeasurable load branches

The current amplitude differential protection is one of the effective means to overcome the deficiencies of the conventional over-current protection in the active distribution network. However, the existing criterions are rarely immune to the unmeasurable load branches especially the IM-type unmeasurable load branches. Therefore, this paper derives the positive-sequence equivalent model of the IM during fault occurrence. Then, the general variation law of the current amplitude difference between both terminals is revealed. For the passive unmeasurable load branch, the current amplitude difference is greater than its original value under internal faults while smaller under external faults. But for the IM-type unmeasurable load branch, such difference can exceed its original value temporarily under external low-resistance faults. To cover the maximum possible current amplitude difference during external fault occurrence, the adaptive operation characteristic curve is established. Accordingly, a novel protection scheme based on the pre-fault and post-fault current amplitude differences is proposed. The simulation results show that the proposed protection can avoid the risk of mal-operation in various external fault scenarios and identify internal faults sensitively.

Droop Control in DC Grids using the Universal Four Leg as Laboratory Setup

Droop control is used for power management in DC grids. Based on the level of the DC grid voltage, the amount of power regulated to or from the appliance is regulated such, that power management is possible. The Universal 4 Leg is a laboratory setup for studying the functionality of a grid manager for power management. It has four independent outputs that can be regulated with pulse width modulation to control the power flow between the DC grid and for example, a rechargeable battery, solar panel or any passive load like lighting or heating

Non-cylindrical wrapping rods and compliant adapters for multi-mode twisting string actuation

In this paper, improvements of the basic twisting string actuation commonly found in the literature are demonstrated based on the addition of two types of passive elements in order to optimise mechanical efficiency. First, the motion speed is increased with non-cylindrical rigid wrapping. Secondly, passive compliant load adjusters are added to improve the overall mechanical advantage of the transmission in reaction to varying loads. A mathematical model of the new system is first detailed in the paper and provides numerical simulations subsequently validated with experimental results. The impact on the important characteristics of the transmission of the design parameters are shown in details and the simulations highlight several improvements of our proposed design compared to existing twisting wire systems. Finally, this novel transmission with a compliant adjuster is used to drive an underactuated robotic finger to demonstrate its effectiveness.

IMMEDIATE IMPLANTATION AND AESTHETIC COMPONENT AS A RESULT OF SUCCESSFUL FORECAST TREATMENT

The aim: Improving the method of immediate implantation in the aesthetic zone in case of bone deficiency to obtain the highest aesthetic and predictable treatment result. Materials and methods: Under clinical observation were 32 patients with different clinical diagnoses in the anterior part of the upper jaw aged 30 to 55 years. In the course of recent advances, the following methods have been used: clinical protocol of immediate implantation with passive exceptional loads by temporary orthopedic constructions, X-ray method using cone-beam computed tomography, statistical analysis. Results: After surgical treatment of patients 1 year after surgery, the distribution of biotypes was as follows: in group 1 – thick biotype 12.87%, medium – 87.13%; in group 2 – thick biotype 27.04%, medium – 72.96%, with p <0.05. According to the results of CT, the distance between the implant and the vestibular in the first group was after 6 months – 1.67 ± 0.04 mm (p <0.05); in the second group of the study we obtained the following results after 6 months – 1.59 ± 0.06 mm (p <0.05). Conclusions: The advanced method of immediate implantation in the anterior part of the upper jaw allows to change the biotype of soft tissues, improve the color spectrum of the gums, increase the thickness of soft tissues with connective tissue autograft, and increase gum density and fixation of osteoplastic material in the presence of defect ), as well as reduce the risk of recession.

Sloshing induced damping in vertically vibrating systems

All aircraft are subject to a range of loading throughout ground and flight operations, which ultimately define the sizing and weight of the aircraft structure. Active and passive loads alleviation technologies provide an approach to reduce dynamic loads arising from atmospheric gusts and turbulence, leading to more fuel-efficient aircraft designs. Within the H2020 SLOWD project, fuel sloshing is being considered as a method for alleviating loads in aircraft wings via an increase in effective damping. Recent work has considered the transient response of a vertically vibrating, single degree of freedom system coupled to a rectangular liquid-filled tank. This research revealed identifiable dissipation regions in the free vibration responses characterised by their own distinct equivalent damping ratio values. In this work, free surface displacement has been extracted from high-speed camera footage during the chosen sloshing regimes, which are representative of a decaying parametrically excited fluid. These results are compared against a fluid-structure coupled numerical model based upon smoothed particle hydrodynamics, previously shown to have good agreement with the experimental damping response. Further analysis of the free-surface response of the numerical solution notes a presence of an undesired travelling longitudinal wave. The analysis of this discrepancy between the model and experiment is then used to improve the numerical formulation, showing a requirement for modelling surface tension.

Economic Dispatch With Distributed Energy Resources: Co-Optimization of Transmission and Distribution Systems

The increasing penetration of distributed energy resources (DERs) in the distribution networks has turned the conventionally passive load buses into active buses that can provide grid services for the transmission system. To take advantage of the DERs in the distribution networks, this letter formulates a transmission-and-distribution (T&D) systems co-optimization problem that achieves economic dispatch at the transmission level and optimal voltage regulation at the distribution level by leveraging large generators and DERs. A primal-dual gradient algorithm is proposed to solve this optimization problem jointly for T&D systems, and a distributed market-based equivalent of the gradient algorithm is used for practical implementation. The results are corroborated by numerical examples with the IEEE 39-Bus system connected with 7 different distribution networks.

Utilizing a High-Speed Marx Supply Modulator in an Amplitude-Modulated Mixerless Transmitter for 64 QAM

This article reports on the theory and application of a high-speed Marx generator (HSMG) circuit to realize supply modulation (SM). In order to achieve high-modulation bandwidth, the supply modulator complexity is kept low, enabling multilevel SM with four discrete voltage levels. A prototype is designed and fabricated on a four-layer FR4 board. The efficiency of the proposed modulator is measured with passive loads, achieving 89% at the 5-MHz switching frequency. Applied to a power amplifier (PA), the modulator demonstrates an error vector magnitude (EVM) of 2.64% at 10-MHz switching frequency with a four-ASK signal. Finally, the HSMG is utilized in an innovative mixerless transmitter architecture. Its capabilities are validated at the center frequency of 3.5 GHz for different modulation bandwidths from 2 up to 70 MHz and different constellation schemes-16 QAM, 32 QAM, and 64 QAM. EVM of 5.88% at 10-MHz bandwidth with 64 QAM is obtained without digital predistortion (DPD).

Dynamic Response Analysis on a 9-Kw Vrfb Test Facility

An industrial-scale Vanadium redox flow battery test facility (IS-VRFB) in operation at the Electrochemical Energy Storage and Conversion Laboratory of University of Padua aims at exploring the technological developments from VRFB laboratory testbeds to grid scale VRFB systems. The 40-cell 600-cm2 active-area stack and two 550-L tanks provide a power of 9 kW and an energy 27 kW h. An AC/DC bidirectional static converter that controlled by the battery management system (BMS) provides the electric power conditioning during charge and discharge with currents up to 75 A and a variable passive load allows high-current discharges up to 600 A. The plant is fully instrumented with electrical and thermo-fluid dynamic probes and the in-house LabVIEW-based BMS provides acquisition, processing and control functions. Since VRFBs are capable of fast response times and can provide fast grid services, such as frequency regulation, it is quite important characterizing their transient behavior. Nerveless, extensive experimental campaigns for investigating the fast response of a large-scale VRFB systems, are largely missing, especially in term of fast time-domain analysis. This presentation is an early contribution in such regard, in view of real large-scale applications of the VRFB technology. Two different time intervals involving different phenomena occurring in the cell have been analysed. Initially, the first 20 ms after battery powering were acquired using an oscilloscope with a sample rate of 2 GHz. Secondly, the first 120 s were explored by means of the BMS acquisition system a sampling rate of 1.25 Hz. In order to widely explore the fast response capability, different conditions were examined by varying state of charge (SOC), flow rate (Q), and current (I). The oscilloscope analyses revealed a “peak transient” time interval during which both current and voltage undergo large variations, up to 50%. During this interval, lasting few milliseconds, no reliable current and voltage value can be provided by the battery. In the longer timescale, different behaviors occurred depending on the Q, SOC, and I. The higher Q and SOC, the shorter the transient before a steady-state condition was achieved, with both current and voltage constant in time (Fig.1a). Preliminary analysis demonstrated the suitability of the model of Fig.1b to predict the stack dynamic response. Modelling resorted to experimental data obtained from a multichannel Electrochemical Impedance Spectroscopy (EIS) analyzer, tailored for IS-VRFB and capable of operating in the range 0─10 kHz with bias currents up to 400 A.

Effects of crowd behavior on dynamic responses of permanent grandstand structure

Constructions industry’s novel design and technological development have resulted in an enhanced use of slender structures having low natural frequency. The overwhelming happiness in concert, shows, sporting events etc., potentialize enthusiastic behaviour of people causes dynamic crowd load i.e., synchronized rhythmic movements may excite supporting slender structures such as stadium, grandstands, auditorium, bridges, malls and convention centre. The combination of slender structures with dynamic crowd load makes the structure easily vulnerable to excessive vibrations and dangerously affects the safety and comfort of occupants. Hence the vibration problems due to increased structural slenderness and dynamic crowd excitation have become more common. So studies regarding the behaviour of dynamic crowd load are mandatory. The present work aims to find out the behaviour of permanent grandstand structure under dynamic crowd load. Here we investigate the behaviour of grandstand structure considering load at different frequency of jumpers in the range of 1.5 Hz to 3.5Hz, different types of activity such as normal jumping, high aerobics and low aerobics and various percentage of active crowd with total crowd, also the effects of rake angle on the structure to reduce the vibration. Active dynamic crowd load was analytically developed as taken from BS 6399-Part 1 and generated as time history and applied to the structure. The passive live load as taken 5kN/m2 specified in IS 875 (Part II). A three dimensional finite element model is used to model the grandstand structure. For modelling the grandstand structure and dynamic analysis finite element software, SAP2000 was used. The results obtained are compared in form of horizontal frequency, vertical frequency, acceleration, displacement, shear force and bending moment.

Nutritional support for children with spinal cord injury at the I—II stages of rehabilitation

The article presents an individual approach to the correction of nutritional status based on the assessment of the need for macronutrients and the degree of motor activity of a patient with a spinal cord injury Objective. To study the needs for macronutrients (energy and protein) and to develop an algorithm of nutritional support for children with spinal cord injury, taking into account their motor activity. Children characteristics and research methods . The study included 44 patients with spinal cord injury from 2 to 18 years old who were admitted to the Research Institute of Emergency Pediatric Surgery and Traumatology in 2015-2019. All patients underwent anthropometric examination, laboratory monitoring and energy consumption using indirect calorimetry and the Harris — Benedict equations. To determine the true energy consumption, the study was carried out at rest, with passive and active loads. Results. The indirect calorimetry method is the most objective method to determine the energy consumption at rest; if it is impossible to use, the Harris — Benedict calculation equations without correction factors are used. The indirect calorimetry method for various types of load helps to calculate correction factors for true energy consumption. Passive motor exercises in the rehabilitation program do not require an increase in nutritional support. The increase in the patient’s motor activity is the critical factor for increasing the volume of nutritional support. To calculate the true energy consumption, it is necessary to take into account the time of patient’s activity and the correction factors obtained. It is necessary to correct protein losses during the period of hypercatabolism (1 month after injury); in the future it is enough to maintain age-related protein needs. Conclusion. The proposed algorithm of nutritional support for children with spinal cord injury can adequately meet the needs for macronutrients and avoid complications associated with their insufficient or excessive consumption.

A Wearable CMOS Impedance to Frequency Sensing System for Non-Invasive Impedance Measurements.

In this paper, we demonstrate a novel non-invasive, wearable impedance sensor. The impedance sensor, using an impedance to frequency measurement, with two modes of resistance and capacitance measurement is implemented in CMOS 130nm technology. The sensor consisting of current and voltage comparators for different mode of measurement, has a low power consumption of 30 μW per channel. The sensor is demonstrated in two applications, thoracic impedance and hand gesture recognition. Thoracic impedance is based on impedance modulation through fluid accumulation. Hand gestures are detected through tissue impedance sensing. The full thoracic impedance sensing system is smaller than a credit card, low cost, and consumes 3mW which includes the sensor, transmitter, and power control unit. Data received by this sensor can be easily transferred for further processing and, eventually, detection of heart failure. The electrodes were implemented using conductive paint, and the system was validated using passive loads to represent human tissue models and test subjects. The hand gesture system operates on 600 μW with the maximum number of electrodes, and uses adhesive copper with electrical paint as electrodes.

The influence of the bound vortex on the aerodynamics of curved wind turbine blades

Passive load alleviation on wind turbine blades can be achieved through geometric bend-twist coupling, for example by sweeping the blade backwards. In order to obtain the correct load distribution of a curved blade with in-plane sweep and/or out-of-plane dihedral, the influence of the blade shape on the aerodynamics must be modelled correctly. This includes the influence of the curved bound vortex, and it is especially important when designing a wind turbine blade with aeroelastic tailoring. In this paper, the background for modelling the curved bound vortex influence will be described in detail and a modified method is proposed. The proposed method of bound vorticity modelling is compared for curved and straight translating wings as well as wind turbine blades with results from a panel code and a Navier-Stokes solver. From this comparison, the advantages of the current modification with respect to the other lifting-line implementations are shown. The method proposed in the present work is general and applicable to any lifting-line like model.

Lightweight optimal rotor design of a 10MW-scale wind turbine using passive load control methods

The present paper investigates the potential to reduce the mass of the blade of the 10MW DTU Reference Wind Turbine through build-in, material bend-twist coupling (BTC). It is materialized by introducing an offset angle on the plies of the uni-directional material over the spar caps of the blade. Optimum BTC designs are obtained on the basis of an integrated optimization framework combining an aeroelastic solver for the calculation of the structural loads of the blade and a cross-sectional tool that provides beam-like structural properties of the blade and stresses distributions. The derived designs are verified based on a subset of representative fatigue and ultimate design loads cases of IEC 61400-1. Reduction of the combined bending moment at the root of the blade by 5% and reduction of the blade mass by 10% is achieved with a hybrid model consisting of three span-wise segments having different constant ply offset angles.

Passive load alleviation on wind turbine blades from aeroelastically driven selectively compliant morphing

AbstractLoad alleviation control is highly desirable to reduce penalties associated with the added structural mass required to withstand rare load scenarios. This is particularly true for wind turbine designs incorporating long‐span blades. Implementation of compliance‐based morphing structures to modify the lift distribution passively has the potential to mitigate the impact of rare, but integrally threatening, loads on wind turbine blades while limiting the addition of actuation and sensing systems. We present a novel passive load alleviation concept based on a morphing flap exhibiting selective compliance from an embedded bistable element. A multifidelity, aeroelastic tool is used to study the shape adaptability of a morphing flap indicating that passive changes from high lift generation to load alleviation configurations can be achieved by exploiting the energy of the flow. This mechanism offers a method to reduce catastrophic peak loads potentially, thus offering the possibility to lower the overall structural weight of wind turbine blades.

Research on advanced design technologies of large-scale wind turbine blades for use in complex terrain

In recent years, wind power has rapidly developed in China’s inland complex terrain. However, the level of core design technologies for related wind turbines is low. Therefore, on the basis of the achievements and experiences of the Institute of Engineering Thermophysics, the Chinese Academy of Sciences for the past 15 years, this study focuses on wind turbine blades, which are essential for the efficiency, reliability, and power cost of the wind power unit. In this study, the new generation of key technologies are researched (e.g., aerodynamic efficiency increase, passive coupling load reduction, and lightweight optimization under complex terrain conditions) to build an integrated optimization design technology system. This study fills the gaps in the domestic industry and strives to make the design level of large-scale Chinese wind turbine blades achieve the international advanced level. In addition, this study is essential for solving national energy security and environmental pollution problems.

Function and strain of the anterolateral ligament part II: reconstruction.

Anterolateral rotatory instability (ALRI) may result from isolated ruptures of the anterior cruciate ligament (ACL) or combined lesions with the anterolateral ligament (ALL). Biomechanical studies have demonstrated that the ALL contributes to the overall rotational stability of the knee. The purpose of this study was to investigate the biomechanical function of anatomic ALL reconstruction (ALLrec) in the setting of a combined ACL and ALL injury and reconstruction. The hypothesis was that combined ACL reconstruction (ACLrec) and ALLrec (ACL/ALLrec) significantly reduces internal rotation and shows load sharing between both reconstructions compared with isolated ACLrec. Eight fresh-frozen cadaveric knees were evaluated using a six degrees of freedom knee simulator. Continuous passive motion and external loads were tested. Kinematic differences between ACLrec and combined ACL/ALLrec were compared. Additionally, ACL graft tension and ALL graft strain were measured continuously throughout the testing protocol. Combined anatomic ACL/ALLrec significantly improved the internal rotatory stability compared with isolated ACLrec at 30°-90° under an internal rotation moment. During a static pivot-shift test, additional ALLrec showed no significant reduction of ap-translation. ALLrec resulted in an increase in ACL graft tension during continuous passive motion and with additional internal rotation moment. In the case of a combined ACL and ALL deficiency, concurrent ACLrec and ALLrec significantly improved the rotatory stability of the knee compared with solely reconstructing the ACL at flexion angles ≥ 30°. Nevertheless, additional ALLrec with fixation at 60° and with low tension could not restore extension-near rotatory stability. For that reason, ALLrec with fixation at 60° flexion cannot be recommended in clinical application.