Load Moment Research Articles

Prediction of functional zones cooling load for shopping mall using dual attention based LSTM: A case study

Prediction of cooling load for each functional zone is essential for implementing an efficient and economic energy management plan in shopping mall. While previous research has been concerned with the overall cooling load prediction of the shopping mall, which could not provide a reasonable control strategy for the on-demand cooling of functional zone in shopping malls. To address this, we present a novel approach to predict cooling load of functional zones in shopping mall which first uses gray relational analysis methods to screen the key influencing factors of cooling load considering the characteristics of cooling load for different functional zones in shopping mall. It then applies LSTM with dual attention mechanism to optimize the output of the prediction model. Feature attention extracts important features through the analysis of the relationship between historical information and input variables autonomously, while temporal attention improves the prediction accuracy by analyzing the importance of load of each historical moment to the prediction of time load. We evaluate the performance of the proposed approach using real data sets from a shopping mall, which locates at Xi 'an, in the north of China. Experimental results show that cooling load prediction based on function zones may not only better satisfy the cooling load demand of diverse zones, but also ensure that chilled water is available on demand for air conditioning systems. Meanwhile, the short-time zonal cooling load prediction model based on dual-attention-LSTM has increased prediction accuracy, generalization ability, and stability when compared to previous prediction models.

Design of Prototype Load Moment Indicator on Mobile Crane using Microcontroller based on Lifting Load Chart

A load moment indicator (LMI) is an electronic device on heavy equipment cranes that can provide information and a warning system to operators in the event of an overload during the lifting load process. This tool has a very important role because it provides accessible information to the operator about the safe working load (SWL) that the crane can lift. Mobile cranes have a high accident potential when compared to tower cranes, and this is because mobile cranes have high mobility. In this paper, a prototype LMI has been made on a mobile crane based on a microcontroller that can provide value. The method used is an algorithm to find the closest value from the lifting load chart of a crane car. The programming algorithm is still manual, namely by equating and comparing boom crane conditions such as boom length, boom angle, and radius contained in the lifting load chart with the results of measuring boom crane conditions by sensors. The nearest value search algorithm follows the rules of how to read the mobile crane lifting load chart. The test results show that the sensors used to measure boom length, boom angle, and actual load each have a maximum relative error of 0.92%, 8%, and 4%, respectively. Meanwhile, to find the SWL value, the comparison scanning method can provide the SWL value according to the lifting load chart of the mobile crane. It can provide accurate information on whether the lifting load process is safe or overloaded.

Failure surface considering the ultimate tensile and compressive capacities of suction caissons in clay

One of the important issues for suction caissons is to demonstrate the effect of the contact between the base and the soil on the ultimate capacities of vertical (V), lateral (H), and moment (M) loads. It has not yet been analytically revealed how the ultimate capacities of suction caissons are dependent on the contact conditions of tension and no-tension interfaces under combined loads including vertical compressive and tensile loads. In this article, an analytical investigation into the effect of interfaces on the ultimate vertical, lateral, and moment capacities of suction caissons in nonhomogeneous clay is made using a traditional bearing capacity theory with tension and no-tension interfaces. For failure envelopes of suction caissons in clay subjected to lateral and moment loads under vertical compressive and tensile loads, the results predicted by the present method are compared with those obtained from the finite element analysis. In order to compare failure envelopes obtained from a tension interface and those obtained from a no-tension interface under general loading, failure envelopes in the H-V, M-V, and H-M planes and in H-M-V space for suction caissons in clay are investigated.

Design and optimization of a joint torque sensor with small crosstalk error for robots

Joint torque sensors (JTS) are often mounted on the joints of a collaborative robot to measure torque but encounters crosstalk problem that affect measurement accuracy. We propose a multi-objective optimized design that considers sensitivity, crosstalk, and stiffness, and develop an anti-crosstalk circuit of a strain gauge-based unit make up a novel JTS. Experimental results show that the maximum crosstalk error was 0.429 Nm under a moment load of 54.384 Nm, 0.274 Nm under a radial load of 295.123 N, and 0.123 Nm under an axial load of 295.123 N without using cross-roller bearings. The proposed JTS can properly deal with crosstalk, and can accurately and directly measure the torque of interest without requiring expensive cross-roller bearings. This simplifies the structural design and reduces the weight and the cost of the robot. These results verify the efficiency and economy of the proposed method of customizing the JTS.

Prompto

Micro-learning [1], cognitive training, and even memory training [2] are a few examples of applications that have been made easier-to-use and more available with mobile, wearable, and ubiquitous technologies. Many of them are also presented through conversational interfaces. Current systems for learning and training focus on providing prompts via notifications to start the training sessions at times when we are available. They use timebased or activity-based reminders to prompt us to engage in the notified tasks, be it learning a new word or playing a cognition-enhancing game. A key challenge is that a well-timed prompt may not be effective if the user is not cognitively available to engage in the intervention [3]. Prompto [4] is a mobile system that opportunistically provides prompts when users are cognitively available: during moments of lowered cognitive load and emotional arousal; these are likely during calm and idle moments. At these moments, we are possibly more receptive to learning and remembering.

Experimental investigation of concrete-filled double-skin stainless steel tubular beam-columns

This paper presents an experimental investigation of the hysteretic behavior of concrete-filled double-skin stainless steel tubular (CFDSST) beam-columns with circular hollow section (CHS) outer and inner. A total of 18 specimens were designed and tested under constant axial compressive load and cyclically increasing flexural load to investigate the structural performance of the composite beam-columns and evaluate the effects of varied design parameters, including the thicknesses of the CHS outer and inner and concrete strength, on the performance of the hysteretic behavior of the CFDSST beam-columns. Both of the lateral load (P) versus lateral displacement (Δ) hysteresis response and moment (M) versus drift angel (θ) hysteresis response were obtained. Based on which, the failure mechanism, ductility, energy dissipation capacity, stiffness degradation, and ultimate strength of the specimens were investigated. The results show that the specimens failed in a ductile mechanism features bulge and rupture at the bottom of the CHS outer, unimpaired CHS inner, and local concrete crush, demonstrating the combined effect of the stainless tubes with the concrete. All of the specimens showed high level of ductility and energy dissipation capacity. Finally, comparisons of ultimate bending moments of the beam-columns between the test results and predictions from the existing design codes and design method demonstrate the deign codes underestimates bending moment strength of the CFDSST beam-columns.

Development of a new improved closed-form plastic collapse moment solution for structurally distorted and through-wall axially cracked 90° pipe bends subjected to in-plane closing bending moment

Plastic collapse loads of 90° pipe bends with structural defects subjected to in-plane closing bending are systematically examined in this study using three dimensional nonlinear finite element (FE) analyses. The analyses consider the large strain formulation option with the pipe bend material assumed to be of the elastic perfectly plastic (EPP) type. Pipe bends are analyzed by changing the ovality at the mid-section which is varied from 0% to 20% by 5% per step. The through-wall axial crack (TAC) parameter at the pipe bend's crown is varied from 0 to 1 by 0.2 per step. Moment rotation curves are drawn for all simulated pipe bend models and plastic collapse moment (PCM) loads are determined from the corresponding moment rotation curves using the Twice-Elastic-Slope (TES) methodology as recommended by clause NB-3213.25 in section III of ASME B&PV code. Both ovality and TAC of pipe bends significantly affects their plastic collapse moments (PCM) and this almost doubles when ovality and TAC act together. The observed effect of ovality and TAC on pipe bends having thin walled and short bend radius does not significantly change with increasing wall thickness and bend radius. The present FE analysis is validated using experimental PCM loads of pipe bends available in open literature. The crack closing effect of pipe bends during closing bending is examined. Based on the analysis, an improved structural integrity assessment equation for shape imperfect pipe bends with TAC is developed for in-plane closing bending moment loads.

Failure Envelopes for Circular Foundations on Two-Layered Clay under Combined Loading

This study numerically investigates the undrained bearing capacity of circular foundations founded on a two-layered clay under combined loading of vertical, horizontal, and moment loads using three-dimensional finite-element analysis. Each clay layer has different thicknesses and shear strengths, and two types of foundation–subsoil interface are considered: an interface with (a) zero tensile capacity or (b) nonzero tensile capacity. Analysis results are presented in the form of normalized failure envelopes for a wide range of layer thicknesses and shear strength ratios. The presented normalized failure envelopes under combined loads with or without the interface tension can be considered as graphical solutions for circular foundations on a two-layered clay in offshore marine environments. Failure mechanisms under various combined loads provide further insights into foundation-layered soil interactions.

Design of arbitrary anchor groups on concrete edge subjected to arbitrary shear load and torsional moment

Design of arbitrary anchor groups on concrete edge subjected to arbitrary shear load and torsional moment

Effect of loading patterns on in-plane flexural hysteretic performance of CHS X-connections

This paper presents an experimental investigations to study the hysteretic behavior of circular hollow section (CHS) X-connections which widely applied in various tubular structures. Cyclic in-plane bending moment (IPBM) loading patterns and geometric parameter of brace-to-chord diameter ratio (β) were varied in testing four connection specimens, to evaluate the influence of load patterns on the hysteretic behavior of the connections. Test results shown that regardless of load patterns and connection details, all specimens showed plump and no pinching effect for the hysteresis curve before cracking occurred, all specimens shared similar final failure modes (the chord wall near the intersection teared) and similar energy dissipation modes (mainly rely on the plastic deformation of the chord wall near the intersection). However, the influence of loading patterns on the hysteretic behavior of the X-connections with varied β is different. For the CHS X-connections with large β, it developed higher flexural strength, better ductility and more energy dissipation performance under synchronized down and up IPBM (SDUI) loading pattern than that under take turns to align clockwise and counterclockwise IBPM (TCCI) loading pattern; while for the X-connections with small β, it is opposite. This experimental observation result was further affirmed by a simplified analytical model and FE analysis results. The test results also indicated that regardless of the load patterns, increasing β trend to significantly improve the strength, ductility ratio and energy dissipation behavior of CHS X-connections under cyclic IPBM, and the current specification trend to give conservative prediction on the in-plane flexural strength of the X-connections.

Horizontal bearing capacity of composite bucket foundation in clay: A case study

Failure of offshore wind power structural system is an important research topic in many countries. Most previous researches focus on the tower failures and blade failures rather than foundation failure. Taking the 3 MW of the composite bucket foundation (CBF) in China as a case study, a comprehensive study of the horizontal bearing response of CBF were carried out by a centrifuge model test and a series of numerical simulations. Results show that the horizontal bearing capacity of CBF increase at first and then decrease with the increase of the existing vertical load in two-dimensional loading space. The relationship between bending moment and horizontal load in two-dimensional loading space is approximate linear. The aspect ratio has influence on the capacity envelopes peak in horizontal-vertical load loading space. Three-dimensional envelope surface is obtained, the results provide a basis for the design of CBF of offshore wind turbine.

Prediction of undrained failure envelopes of skirted circular foundations using gradient boosting machine algorithm

Skirted circular foundations have been widely used in offshore engineering and are subjected to combined vertical (V), horizontal (H) and moment (M) loading. Undrained load-carrying capacities of skirted circular foundations under combined V–H-M loading were derived from the finite element limit analysis (FELA) in this paper considering a wide range of embedment ratios and soil strength heterogeneity indices. A double-ellipse fitting strategy was proposed and employed to fit numerical results with a unified failure envelope expression. Due to complex interactions between different variables, gradient boosting machine (GBM) algorithm was introduced to learn the relationship between fitting parameters in the failure envelope expression and their influencing variables based on the database constructed by FELA. The results in this study show that the double-ellipse fitting strategy provides comparably accurate and more conservative predictions of failure envelopes compared with existing fitting strategies. The GBM model developed in this study has a good performance in predicting fitting parameters of failure envelopes. The importance of influencing variables and the effect of database size and data orthogonality on the performance of GBM model were discussed. The method based on double-ellipse fitting strategy and GBM algorithm can be implemented in a program to generate failure envelopes conveniently.

A review of equine tibial fractures.

Equine tibial fractures are relatively infrequent in racing and non-racing sport horses, but limitations in successful treatment of tibial fractures in adult horses result in relatively high mortality compared with other musculoskeletal injuries. The aetiology of tibial fracture can be classified into two general categories: traumatic impact or fatigue failure. Tibial stress fractures, also known as fatigue fractures, are often rated as the second most common stress fracture in racing Thoroughbreds; young age, early stage in race training, and initiation of training after a period of rest are the reported risk factors. Both impact and fatigue fracture propagation are dependent on the magnitude of force applied and on the local composition/alignment of mineralised collagen in the tibial lamella. Extensive research has characterised the pattern of strain distribution and stress remodelling within the equine tibia, but in vivo measurement of load and angular moments are currently not feasible. Further research is warranted to correlate biomechanical theory of tibia fatigue fracture propagation with current histopathological data. Preventative measures for fatigue fractures aim to optimise diagnostic efficiency, reduce the interval between injury and diagnosis and modify racing and training conditions to reduce non-specific fracture risk. Treatment options for complete tibial fractures in adult horses are limited, but with careful case selection, successful outcomes have been reported after open reduction and internal fixation. On the other hand, tibial stress fractures and minimally displaced incomplete fractures are typically treated conservatively and have good prognosis for athletic recovery. This review aims to describe the current literature regarding tibial fracture aetiology, prevalence, risk factors, fracture biomechanics, treatment, prognosis and prevention.

Assessment of pavement deflection under vehicle loads using a 3D-DIC system in the field.

This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing of pavements and to support the development of techniques for a rapid evaluation of the conservation status of existing roads. Little research was found on this topic. The passage of a car wheel on an asphalt pavement was adopted as a case study. The DIC measurements were compared to those gathered by contact sensors. From a qualitative point of view, the DIC measurements captured the realistic shape of a deflection basin. From a quantitative point of view, the deflection values provided by the DIC system had a mean error of 0.015 mm and a standard deviation of 0.011 mm. At the moment of highest load, these errors had a mean value and standard deviation of − 0.016 mm and 0.021 mm, respectively. Thus, to improve the accuracy of the system, we propose modifying the camera support, speckle pattern, and control of natural light.

Novel force–displacement control passive finite element models of the spine to simulate intact and pathological conditions; comparisons with traditional passive and detailed musculoskeletal models

Passive finite element (FE) models of the spine are commonly used to simulate intact and various pre- and postoperative pathological conditions. Being devoid of muscles, these traditional models are driven by simplistic loading scenarios, e.g., a constant moment and compressive follower load (FL) that do not properly mimic the complex in vivo loading condition under muscle exertions. We aim to develop novel passive FE models that are driven by more realistic yet simple loading scenarios, i.e., in vivo vertebral rotations and pathological-condition dependent FLs (estimated based on detailed musculoskeletal finite element (MS-FE) models). In these novel force–displacement control FE models, unlike the traditional passive FE models, FLs vary not only at different spine segments (T12-S1) but between intact, pre- and postoperative conditions. Intact, preoperative degenerated, and postoperative fused conditions at the L4-L5 segment for five static in vivo activities in upright and flexed postures were simulated by the traditional passive FE, novel force–displacement control FE, and gold-standard detailed MS-FE spine models. Our findings indicate that, when compared to the MS-FE models, the force–displacement control passive FE models could accurately predict the magnitude of disc compression force, intradiscal pressure, annulus maximal von Mises stress, and vector sum of all ligament forces at adjacent segments (L3-L4 and L5-S1) but failed to predict disc shear and facet joint forces. In this regard, the force–displacement control passive FE models were much more accurate than the traditional passive FE models. Clinical recommendations made based on traditional passive FE models should, therefore, be interpreted with caution.

Simple lower bound limit analysis model for masonry double curvature structures

A new Lower Bound LB plate and shell limit analysis Finite Element FE model for the analysis at collapse of masonry double curvature structures is presented. The discretization relies into hexahedrons assumed infinitely resistant and quadrilateral interfaces where all plastic dissipation occurs. On such interfaces, the flexural behavior is ruled by the interaction between bending moment and axial load, whereas the shear and torsional behavior are modeled by means of an in-plane tangential force, out-of-plane shear and a plate torque. The resultant limit analysis problem obtained by such a formulation is particularly straightforward and the number of variables to deal with very limited. Equilibrium is indeed imposed only on hexahedrons and admissibility on interfaces between adjoining elements. Masonry can be modeled obeying a classic no-tension material or with more complex linearized failure surfaces, for example derived from suitable homogenization techniques. A simple Linear Programming LP problem is so derived, where the actual thickness of the structure is accurately accounted for, a key feature to assess the stability of a vault in case of the no-tension material assumption. The numerical model is validated by means of several meaningful structural examples. A detailed comparison with numerical data available in the literature, obtained for the same examples with alternative numerical approaches shows the accuracy of the method proposed and its usefulness for a fast and reliable prediction of the load carrying capacity of masonry double curvature structures.

Analytical calculation of the coefficient of increasing the moment of resistance to milling the ground when the cutter hits the stump

One of the main operations in peat soil processing is milling. The entire subsequent production process depends on the quality of the milling. The presence of wood inclusions in the soil greatly complicates the work. The sharply increased moment of loading that occurs when the cutter hits the stump is capable of removing both the transmission elements and the drive of the milling unit from the operational state. Therefore, at the design stage, it is necessary to take into account the dynamic loads arising from the meeting of the cutter with wood inclusions. Attempts to describe this fact were made earlier by various authors, but due to mathematical and methodological errors, they were not crowned with success. In this article, an attempt was made to "work on errors", which allowed one, taking into account all the previous errors and inaccuracies, to achieve the desired result.

An analytical solution to estimate the critical buckling load of doubly-curved laminates under a combined load of uni-axial compression, in-plane shear and bending moment

Curved panels are structural elements that form the skin of wings, fuselages and tail booms in aircraft. Buckling of these structures would adversely affect aircraft performance. Due to this, the problem of buckling has been extensively researched in the past. Most of the research has been restricted to the analysis of flat composite panels and analysis of curved panels through simplifications involving geometry, material properties and boundary conditions. The present study aims to develop an analytical solution that can predict the critical buckling load for a wider range of problems. An analytical solution was developed in order to obtain the critical buckling load for a doubly-curved composite laminate under compression, shear, moment or any combination of the three loads. The assumptions of the classical laminate plate theory were used in order to obtain the displacement fields as well as strains of the laminate. The energy method was employed in order to obtain the critical buckling load for various load cases. The values obtained through the analytical solution are compared to the critical buckling loads obtained through finite element analysis (FEA). The highest deviation of critical buckling load from FEA was calculated to be 16.55%. Variation of the critical buckling load with respect to the radius of curvature, boundary conditions and stacking sequence was analyzed. The developed solution was also found to be valid for cases when radii of curvatures are unequal as well as when the length and breadth of laminate are unequal.

Numerical study on the bearing capacity of strip footing resting on partially saturated soil subjected to combined vertical-horizontal-moment loading

This study investigates the bearing capacity of strip footings resting on unsaturated soils subjected to combined loading using the lower-bound limit analysis coupled with the finite element discretization approach. In this regard, second-order cone programming (SOCP) is exploited to simulate the nonlinear form of the universal Mohr-Coulomb yield criterion during the process of stress field optimization. The significant influence of matric suction induced below the surface footing was accounted for by adopting the suction stress concept under the no-flow and steady-state infiltration/evaporation flow conditions. The eccentricity and inclination of the foundation loading are introduced into the equilibrium equations along the strip footing so as to render various combinations of moment (M), vertical (V) and shear (H) forces. The results stemming from the lower-bound finite element limit analysis are compared with several previous studies throughout the literature for verification of the model. The substantial contribution of suction stress to the evolution of failure loci and the distribution of subsurface stresses for the shallow foundation subjected to inclined and eccentric loadings is thoroughly discussed. A general three-dimensional failure envelope is presented for shallow foundations resting on partially saturated soils under combined vertical, horizontal and moment loadings.

Finite element study of the impact of pedicle screw density on the biomechanical response of a Lenke 1AN scoliotic curve

IntroductionBenefits of increasing screw density in posterior instrumentation used to treat a scoliotic deformity are demonstrated using a three-dimensional finite element model (FEM) of the thoracolumbosacral spine. MethodsThe FEM represents a Lenke 1AN scoliotic deformity with a 50° Cobb angle and 20° apical vertebral rotation. The curve is corrected with bilateral pedicle screw fixation and 75 separate randomized screw distributions. ResultsTotal construct screw density, concave rod screw locations at T6, T10, T11 and T12, and convex rod screw locations at T7 and T12 each correlate strongly with reductions in postoperative Cobb angle (P < 0.05). Apical vertebral rotation is greatly impacted (reduced) by screws placed at the apical vertebra on both concave and convex rods (P < 0.05). Under pure moment loading, intersegmental micromotion is generally reduced when motion segment screw density is increased, with the exception being the upper instrumented joint. ConclusionsThese results suggest that increasing the screw density of posterior constructs used to treat a Lenke 1AN scoliotic deformity may improve the de-rotation correction with better postural restoration, reducing the risk of future complications including pseudarthrosis.