Load Location Research Articles

Identifying interactive effects of task demands in lifting on estimates of in vivo low back joint loads

This investigation examined interactions between the magnitude of external load, movement speed and (a)symmetry of load placement on estimates of in vivo joint loading in the lumbar spine during simulated occupational lifting. Thirty-two participants with manual materials handling experience were included in the study. Three-dimensional motion data, ground reaction forces, and activation of six bilateral trunk muscle groups were captured while participants performed lifts with two loads at two movement speeds and using two load locations. L4-L5 joint compression and shear force-time histories were estimated using an EMG-assisted musculoskeletal model of the lumbar spine. Results from this investigation provide strong evidence that known mechanical low back injury risk factors should not be viewed in isolation. Rather, injury prevention efforts need to consider the complex interactions that exist between external task demands and their combined influence on internal joint loading.

A Broadband VHF/UHF-Loaded Dipole Antenna in the Vicinity of a Human Body

A broadband dipole antenna with a very simple low-cost mechanical structure is proposed. This dipole of the height of 173 cm with inductor/resistor ( LR ) loading circuits is designed to operate in the frequency range of 30–512 MHz—hence a 17:1 bandwidth (178%). By choosing the optimized location of LR loads, the radiation pattern is controlled. Meanwhile, the VSWR 1:3.5 is adjusted by an input matching circuit, tuning a number of LR loads, and using a transmission line transformer. The impedance matching is better than −6.5 dB in whole frequency bandwidth. The antenna gain is gradually increased from −20 dBi at 30 MHz to −2 dBi at 512 MHz. The manufactured prototype is presented along with its measured characteristics which map well onto software simulated counterparts. The antenna is considered to be used in portable applications. Therefore, the simulations and the measurements are conducted near the human body. A simple model of the adult human body at the frequency band of the proposed antenna is used, which helps to study the effects of the human on the antenna performance. Moreover, the electromagnetic exposure on the human body is investigated. Experimental evidence is presented to verify the conclusion.

Forced vibration of porous functionally graded nanoplates under uniform dynamic load using general nonlocal stress–strain gradient theory

Forced vibration analysis of porous functionally graded nanoplates under uniform dynamic loads is performed based on generalized nonlocal strain gradient theory. In this model, both stiffness-softening and stiffness-hardening effects are considered for more reliable forced vibration analysis of nanoplates. The present model is based on a vibrating higher order nanoscale plate subjected to transverse uniform dynamic load. Nanopores or nanovoids are incorporated to the model based on a modified rule of mixture. According to t Hamilton’s principle, the formulation of dynamically loaded nanoplate is derived. Applying Galerkin’s method, the resonance frequencies and dynamic deflections are obtained. It is indicated that the forced vibration characteristics of the nanoplate are significantly influenced by the porosities, excitation frequency, nonlocal parameter, strain gradient parameter, material gradation, elastic foundation and dynamic load location.

The experimental parameters that affect attentional modulation of the ERP C1 component

ABSTRACTThere is current debate as to whether spatial attention can modulate V1 activity during the initial wave of visual processing. Research on this topic has focused on the event-related potential (ERP) C1 component, which primarily reflects activity in V1. The purpose of the present selective review was to compare experimental parameters across spatial attention studies to determine whether certain stimulus, task, or analysis conditions were more likely to produce significant C1 attention effects. Specifically, C1 attention effects were evaluated as a function of visual field location, presence or absence of distractors, load (perceptual or attentional), cue type (endogenous or exogenous), and electrode location. As the C1 component has its peak magnitude at midline parietal-occipital electrodes, only studies that measured C1 attention effects at these electrode locations were considered. Furthermore, only studies that manipulated spatial attention, and no other factors, were considered. The current analysis indicated that to maximize sensitivity to C1 attention effects, stimuli should be in the upper visual field, there should be distractors, conditions should be high perceptual or attentional load, there should be exogenous cuing, and effects should be measured at midline parietal-occipital electrodes POz, Pz, and CPz.

Load location identification of fiber optic smart structures based on a genetic algorithm–support vector regression

A load location identification method of fiber optic smart structures based on a prototype data acquisition system is proposed. It employs a genetic algorithm–support vector regression to estimate the X, Y coordinates of loads loading on a composite panel. The panel is embedded with 8 sensors. When loads act on any position of smart composite structures, the output values of embedded fiber near the loading position will change. The 8 changed signals are the features of the genetic algorithm–support vector regression. The data acquisition center collects the features as the data samples. Data samples are divided into a training set, a validation set, and a testing set. Then a support vector regression model is established by using the training set and validation set, and the parameters are optimized by the genetic algorithm. The study compares the prediction accuracy between the genetic algorithm–support vector regression model and the back propagation model. The comparison results show that the prediction accuracy of the testing set was 85.78% and it is better than the back propagation neural network prediction model. This paper demonstrates that using the genetic algorithm–support vector regression model to identify loads is not only stable and feasible but also has high precision. The presented method in this paper is significant for the health monitoring and damage identification of composite materials in the future.

White Matter Integrity in Subcortical Vascular Cognitive Impairment: A Multimodal Structural MRI Study.

To investigate the disruption of white matter (WM) integrity in patients with subcortical vascular cognitive impairment (SVCI) with multimodal structural magnetic resonance imaging (MRI), and to explore the relationships between WM damage, structural network disruptions, and general cognitive function decline. Twenty-eight patients with SVCI and twenty control subjects underwent structural MRI scans and neuropsychological assessment. WM volume (WMV), WM hyperintensities (WMH), lacunar infarcts (LI), diffusion tensor imaging parameters and structural network characteristics were compared between two groups. Correlations between these parameters and general cognitive function were calculated. WMV, WMH load, LI number, mean fractional anisotropy (FA), peak height and peak location of mean diffusivity (MD) of normal-appearing WM (NAWM) and structural network characteristics were significantly different between the two groups. Disruption of WM microstructure and network characteristics was widespread. WMV, WMH load, mean FA and peak location of MD of NAWM explained about 70% of the variance in structural network characteristics. Shortest path length with LI number explained 47.5% of the variance in z-scores. SVCI was associated with widespread disruptions of WM integrity in the brain. Network characteristics may be a comprehensive reflection of WM integrity and a superior predictor of general cognitive function, while LI was an independent predictor of cognitive impairment.

Continuum topology optimization considering uncertainties in load locations based on the cloud model

ABSTRACTFew researchers have paid attention to designing structures in consideration of uncertainties in the loading locations, which may significantly influence the structural performance. In this work, cloud models are employed to depict the uncertainties in the loading locations. A robust algorithm is developed in the context of minimizing the expectation of the structural compliance, while conforming to a material volume constraint. To guarantee optimal solutions, sufficient cloud drops are used, which in turn leads to low efficiency. An innovative strategy is then implemented to enormously improve the computational efficiency. A modified soft-kill bi-directional evolutionary structural optimization method using derived sensitivity numbers is used to output the robust novel configurations. Several numerical examples are presented to demonstrate the effectiveness and efficiency of the proposed algorithm.

Effect on Stresses of Structural Details of Orthotropic Steel Deck with Thin Surfacing

Although it has the advantage of decreasing the loads on bridge deck when adopting thin surfacing, it is worse for the stress dispersion of vehicle loads, as a result, it is easy to generate local stress concentration of structural details of orthotropic steel deck. To study the stresses of orthotropic steel bridge decks, especially for the structural weld details, which is significant for fatigue durability evaluation. Partial models are created by finite element analyses to analyze the stresses of both normal thickness bridge pavement and thin surfacing under different load locations, and the kinds of material of pavement and the thickness of bridge deck are also considered in the calculations. It’s found that stress amplitude of objective fatigue details of TPO pavement increase up to 28.4% when the models share the same structure dimension, and the thickness of TPO pavement has little impact on the stress amplitude of objective fatigue details which could be ignored, while the influence of the thickness of the TPO pavement is considerable. And the increase of the thickness of bridge deck helps decrease the stress amplitude of objective fatigue details.

The Impact and Placement of Photovoltaic Distributed Generation in Ship Distribution Network for Loss Reduction

Recent advances in photovoltaic (PV) technologies, controls, and power converter topologies have resulted in the increasing application of green energy from solar in ship power system. However, there is very few research on the loss changes of shipboard distribution network produced by introduction of PV distributed generation. In this paper, we report on one ideal model and one model with an example of chain nine nodes distribution network for analyzing the impact and placement of ship distribution network with PV distributed generation. After empirical analyses, we concluded major results as follows: 1) the proper configuration of PV generation in the traditional power network can reduce the loss of distributed network effectively; 2) PV generation should be installed at the middle location of total loads; 3) the capacity of PV generation should approach the capacity of total loads; 4) PV generation should work at the lagging power factor.

In vitro release profiles of PLGA core-shell composite particles loaded with theophylline and budesonide

We investigated the effects of drug loading location, matrix material and shell thickness on the in vitro release of combinational drugs from core-shell PLGA (i.e., poly(lactic-co-glycolic acid)) particles. Budesonide and Theophylline were selected as highly hydrophobic and hydrophilic model drugs, respectively. The dual-capillary electrospray (ES) technique, operated at the cone-jet mode, was used to produce samples of drug-loaded core-shell composite particles with selected overall sizes, polymer materials, and shell thicknesses. Theophylline and Budesonide were loaded at different locations in a PLGA composite particle. This study illustrated how the aforementioned factors affect the release rates of Budesonide and Theophylline loaded in core-shell PLGA composites. We further identified that core-shell composite particles with both model drugs loaded in the core and with matrix PLGA polymers of low molecular weights and low LA/GA ratios are the best formulation for the sustained release of highly hydrophilic and hydrophobic active pharmaceutical ingredients from PLGA composite particles. The formulation strategy obtained in this study can be in principle generalized for biopharmaceutical applications in fixed-dose combination therapy.

Analysis, design and implementation of a residential inductive contactless energy transfer system with multiple mobile clamps

This study presents the analysis, design and implementation of a simple and cost-effective residential inductive contactless energy transfer system with multiple mobile clamps. The topology is based on the cascaded connection of a buck converter and a high-frequency resonant inverter loaded by several output passive rectifiers. The proposed system includes a sliding transformer to supply the mobile loads, leading to a safe and flexible location of loads. The theoretical analysis and design of the proposed system is based on a mathematical model derived using the first harmonic approximation. Selected experimental results are included to verify the system features. In comparison with conventional topology, the proposed system significantly improves efficiency, complexity and cost.

Retraction Notice: The WSN Energy Efficient Protocol Based on Adaptive Mechanism of Sleep

In view of node energy limitation in the wireless sensor network, efficient energy saving strategy has become one of the hot spots in the wireless sensor technology. Through the analysis of the energy efficiency solution of wireless sensor network in each layer, put forward a kind of wireless sensor energy efficient protocol based on adaptive sleep mechanism. The scheme according to the residual energy storage, location and degree of adjacent nodes load, using vari- able duration of sleep mechanism to choose forward grouping way. Compared with the random transmission scheme based on the geographical position, the given scheme can save the network node energy greatly and balance the network energy consumption effectively. Therefore, this scheme can improve overall network life significantly.

SURVEY AND RESTORATION: NEW WAYS OF INTERACTION

Abstract. The present paper analyses two cases exemplifying a possible use of survey and its elaborations in the field of conservation: the bell tower of the Basilica Santa Maria delle Vigne and the Chiesa di San Matteo, both situated in Genoa. In the first case, the threedimensional survey was used as a basis to build a model for the structural analysis. The need for an accurate database created with the three-dimensional survey allowed the research team to determine and highlight the critical points of the structure as the thickness of vaults and floors, the location of loads and the inclination of the walls. The data collected was used to create an accurate 3D model to be tested with simulations, in order to verify the stability of the bell tower when applying stress and limitations. In the second case, the three-dimensional survey was used as the basis for the collection, management and representation of the data derived from the survey on rising damp. The purpose was to test a dynamic data processing system that could be used as a tool to collect data on site as well as to access data remotely. By using software for three-dimensional representation and a node programming language, it was possible to define a system that offered dynamic viewing and was easy to use, through the use of chromatic scales and level curves, which can be generated starting from tables containing numerical data. Surveying, diagnostics, modelling and representation allow one to experiment with new ways of interaction within the common goal of conservation.

Accuracy of Manual Surgeon-Defined Assessment of Soft Tissue Balance in TKA In Comparison to Sensor-Guided Measures and its Effect on Final Balance

Objectives:Present literature supports the importance of final alignment and soft tissue balance in total knee arthroplasty (TKA) on implant survivorship and clinical outcomes. Current soft tissue balance techniques mostly depend on subjective static measures that don’t allow for quantitative determination of ligament tension. Sensor guided technique (Verasense, Orthosensor) allows demonstration of the magnitude and location of load in a dynamic way providing quantitative data about knee balance. The aim of this study is to test the accuracy of the surgeon’s manual assessment in judging knee balance in comparison to Verasense. We also aimed to determine whether Verasense can assist in achieving soft tissue balance from the unbalanced state.Methods:58 patients were enrolled in this prospective cohort study. The level of agreement between SDA and Verasense at 10, 45, 90 degrees was recorded. Initial trial pressures and final pressures after release or re-cut were recorded and compared. Final pressure measurements were then documented to assess whether appropriate knee balance (differential compartmental pressure of 15 lb/inch on 2 or more angular positions) had been achieved.Results:The mean age of the cohort was 67.5 years with deformities ranging from -16 degrees of varus to +20 degrees of valgus (mean -1.26 degrees varus). The capacity for the surgeon to manually identify an unbalanced knee was low with a test sensitivity of 33.3%. Manual test specificity to define a balanced knee was better with a specificity of 77.3%. The manual test had a positive predicitive value of 59.2% and a negative predictive value of 54%. There were 46.5% (27 of 58) of cases where the Verasense lead to a different surgical plan to that initially determined by the manual assessment. In 23 cases, either ligament release or tibial bone recut was performed. In the remaining 4 cases, the Verasense prevented a ligament release being performed. 95% of cases achieved a balanced state within 15lb/inch of pressure between compartments, with 100% balanced within 25 lb/inch.Conclusion:Manual surgeon assessment of soft tissue balance is a poor predictor of unbalanced knees. Verasense has the capacity to subsequently balance the knee within an acceptable pressure range as defined by prior studies. Further analysis to determine the impact on patient outcomes and implant survivorship is warranted.

Scope of inextensible frame hypothesis in local action analysis of spherical reservoirs

Spherical reservoirs, as objects perfect with respect to their weight, are used in spacecrafts, where thin-walled elements are joined by frames into multifunction structures. The junctions are local, which results in origination of stress concentration regions and the corresponding rigidity problems. The thin-walled elements are reinforced by frame to decrease the stresses in them. To simplify the analysis of the mathematical model of common deformation of the shell (which is a mathematical idealization of the reservoir) and the frame, the assumption that the frame axial line is inextensible is used widely (in particular, in the manual literature). The unjustified use of this assumption significantly distorts the concept of the stress-strain state. In this paper, an example of a lens-shaped structure formed as two spherical shell segments connected by a frame of square profile is used to carry out a numerical comparative analysis of the solutions with and without the inextensible frame hypothesis taken into account. The scope of the hypothesis is shown depending on the structure geometric parameters and the load location degree. The obtained results can be used to determine the stress-strain state of the thin-walled structure with an a priori prescribed error, for example, in research and experimental design of aerospace systems.

Finite element analysis on tooth and periodontal stress under simulated occlusal loads.

The tooth stress elicited by occluding contact represents critical biomechanical information about dental health during chewing. Effects of occlusal contact on tooth stress remain obscure. In this study, a mandibular first molar finite element model was built from CT images. The effects of area size, location and direction of occlusal loading on both tooth and periodontal stresses were analysed. Results showed tooth and periodontal stress had drastically different patterns. Tooth stress value was much higher than periodontal stress value under the same task. Tooth stress concentration area and its value decreased from outside to inside. The Maximum Tooth Stress (MTS) always occurred at the loading site and a larger loading area elicited a smaller MTS value. The variation of MTS was larger when the fossa bottoms were inclined loaded than when the cusp tips were inclined loaded, larger when lingually loaded than when buccally loaded and larger when mesially loaded than when distally loaded. Distal loadings generally induced smaller Maximum Periodontal Stress (MPS) variations than the mesial loadings. These findings indicated exposure of the rational site(s) to occlusal contact should be helpful to achieve proper tooth and periodontal stress, thus to diminish loading associated structure problems.

Disbond detection and load estimation on a composite test box using Fiber Bragg grating sensors

Detection of hidden damages such as disbonds and delaminations are of relevance to the safety and maintenance of composite airframe structures. This study explores damage identification and load estimation using artificial neural networks (ANNs) on a composite test box. The objective is to detect disbond between spar and skin of the composite box using strain measurements made using fiber optic sensors. A novel approach is devised to create disbonds of various lengths using a non-adhesive insert between top skin and flange of centre spar. Initially a large disbond is created and progressively the disbond size is reduced in stages to obtain a healthy structure. The composite box is loaded at every stage and strains are acquired at various locations in the box using fiber Bragg grating (FBG) sensors. The difference in strains between healthy and unhealthy stages of the box is indicative of the presence of damage, as well as its extent and the loads acting on the structure. ANNs are trained using data generated from numerical models of the composite test box for healthy and disbond cases. These trained ANNs are then used to estimate the applied load, disbond size and disbond location using experimental strain data.

NEW ENERGY PRINCIPLES OF STRUCTURES RATIONALIZATION

This paper examines the method of direct design of structures, which is based on usage of the compiler founded by finite element method (FEM) and method of adaptive evolution (MAE). In this connection, the concept of the reference stress-strain state of the system formed by sequential build its energy equally strong counterpart is introduced. In this case, the refinement exposed, in general, not only the geometry, but also the physical and mechanical properties of elements. At the same time, it has the opportunity to varying characteristics such as coordinates of the bearing design, constraint type, load location, and others. The result of indicated approach is to build an energetic portrait of the system, including the definition of the system topology, characterized by a minimum value of the accumulated during deformation, potential energy and uniform (quasiuniform) distribution of potential energy density. In the above test examples illustrated approach priorities and features of derived implementations Relationship between known criteria of structure parameters rationalization and new ones introduced in this paper is denoted. Noticed reference stress-strain state of the system is the first approach of the formation of the final decision. Therefore, in the paper, based on the exploitation of Kieffer-Johnson method a sequence of procedures for its numerical implementation is revealed. Derived results are the basis for CAD algorithm design of structures with improved characteristics.

Simulation of Distance Relay for Load Encroachment Alleviation with Agent Based Supervision of Zone 3

Cascaded tripping of power lines due to mal-operation of zone-3 distance relays has been one of the main causes of many previous blackouts worldwide. Encroachment of load into zone-3 characteristics during stressed system operation conditions is a basic factor for such mal-operation of the relays. By improving the operation of zone-3, it is possible to prevent mal-operations so that cascaded line tripping can be avoided. For proper study of the behavior of distance relay during faults and load encroachment phenomenon, we must build a model of distance relay, so in this paper a modeling study of distance relay is implemented using MATLAB/Simulink program. However, this model is distinguished from previous models that, examines in detail the third zone of distance relay. Many cases are simulated with changing line loading and fault location to ensure the capability of the relay to detect the fault and thus the maximum load ability limit of distance relay is obtained. In order to prevent cascading events caused by hidden failures in zone-3 relays, agent based relay architectures have been suggested in the recent past. In such architectures each zone-3 relay contains agents that require communication with other agents at various relevant relays in order to distinguish a real zone-3 event from a temporary overload. In this paper, a local master agent is consulted by all zone-3 agents before a tripping decision is made. The master agent maintains a rule base which is updated based on the local topology of the network and real time monitoring of the status of other relays and circuit breakers. Cisco Packet Tracer program is used for running communication network simulations. The result of the simulation indicate that the time estimated to send and receive a packet data unit (PDU) message between one relay to anther can satisfy the communication requirement for the proposed scheme with fiber media.

HPC-Based Probabilistic Analysis of LV Networks With EVs: Impacts and Control

Distribution network analyses have been traditionally carried out by sequentially processing computational tasks, i.e., without taking advantage of parallel processing now available in multi-core machines. However, future distribution networks require studies that cater for the uncertainties due to the location and behavior of loads and low carbon technologies, resulting in a much more computationally demanding environment. This paper investigates the adoption of high performance computing (HPC) to accelerate probabilistic impact and control analyses carried out on residential low voltage (LV) networks with electric vehicles (EVs). First, the impacts of uncontrolled charging of EVs are quantified using a Monte Carlo-based approach using 1000 time-series daily simulations per penetration level (i.e., 0%–100%). Then, to mitigate these impacts, the coordinated management of the on-load tap changer and EVs is proposed considering a preventive control approach that caters for the uncertainties ahead (1000 scenarios). Two real residential, underground U.K. LV networks considering realistic demand and EV load profiles (1-min resolution) are analyzed. Results show that the processing time for the impact analysis is reduced almost proportionally to the number of cores. From the control perspective, it is demonstrated that HPC can be a feasible and implementable alternative in the management of future smart grids.