Element Length Research Articles

A FRAMEWORK FOR PROCESS-RESOURCE REQUIREMENTS PREDICTION IN A FACTORED OPERATING SYSTEMS USING MACHINE LEARNING

The evolution of multicore technology has come with new challenges to process scheduling. An intelligent process resource requirement prediction framework in a factored operating system (FOS) was developed using machine learning. To simulate this system, an array of positive integer numbers in the interval of 1 to 10, with a maximum length of 20, was used to represent process. The properties of this array (array length and sum of the array elements) were used as the parameters of the application processes. These served as input into the machine learning network to predict the process’ size and hence, the resource requirements for each process. The framework was simulated using Java 2EE. Experimental results of the framework showed that prediction of processes’ sizes with enhanced resource requirement allocation, and hence, required faster and efficient scheduling of processes to multiple resource cores, with an increased system throughout.

Phase-field fracture modeling for creep crack

Creep cracks will significantly impact the structure’s safety under high temperatures. Currently, most phase-field models describe the creep crack growth by considering the viscous strain energy as a part of the driving force. This work proposes a phase-field model for creep crack in elasto-plastic materials with a different approach. A creep degradation function of creep strain acting on fracture toughness is introduced to describe the effect of creep on crack growth. And it is modified with a function of stress triaxiality to consider the effect of multiaxial stress. Several numerical examples are simulated to validate the presented model. In addition, some parametric studies are performed for different element sizes, length scales, and creep parameters.

Hydraulic Capacity of Bend Manholes for Supercritical Flow

Sewer bend manholes are frequent elements of urban drainage systems. Any deviation of straight-lined supercritical flow, as within the manhole, generates shock waves, possibly impinging at the manhole end or imposing a hydraulic jump. Then the free-surface flow regime abruptly breaks down and backwater effects occur. Thus it is important to know the maximum discharge that safely can pass across a bend manhole, as a function of its geometry, without generating collapsing flow. This study conducted calibrated numerical simulations to assess the hydraulic features of supercritical bend manholes with variable deflection angles, curvature radii, and lengths of straight downstream extension elements. The numerical model was validated previously with data from analogous physical model tests documented in the literature. The combined data from the numerical simulation and from the physical model indicated a hydraulic capacity of the bend manholes for different geometrical setups. It was demonstrated that the hydraulic capacity of a bend manhole increases with increased curvature radii and straight extension lengths, whereas the effect of the deflection angle is less significant. A multiple regression technique provided an empirical equation indicating the normalized discharge capacity of supercritical bend manholes as a function of the governing geometrical parameters, along with the approach flow filling ratio.

THE IMPACT OF OIL PRODUCTION ON THE EROSION NETWORK DEVELOPMENT IN VOLGA-URAL STEPPE REGION

The purpose of the work is to consider the features of the erosion network development of the in the steppe zone with mixed agricultural and oil-producing land use. The research was carried out on six key study plots with an area of 100 km2 each which allocated within the Volga-Ural agricultural and oil region. Satellite images and fieldwork were used to digitize, map and classify erosive landforms. The main directions of erosion activity at key plots are identified for the period from 1985 to 2020. The analysis of the length and density of the spatial distribution of the erosion elements is carried out. It is shown that the activation of production activities at an oilfield is capable of initiating new and strengthening current erosion processes. During the time of maximum technogenic load, the total length of the erosion elements can increase by more than 50%. There is a steady increase in the total length of the erosion network during the increase in the time of operation of the oil field. Agricultural lands located in the zone of the oilfield are influence increased risk of soil erosion. In such cases, the tasks of protecting land from technogenic transformations and their return to agricultural circulation are actualized.

Elastic shear buckling of cold-formed steel channels with edge stiffened web holes

Cold-formed steel (CFS) beams are commonly deployed in construction with web holes to accommodate service conduits. The web holes are subjected to stiffening methods aiming to restore the load-carrying strength reduction. In the shear design of CFS channels with stiffened web holes, the elastic shear buckling strength is the basis for the design irrespective of the available post-buckling strength. Therefore, this paper investigates the elastic shear buckling characteristics of CFS channels with stiffened circular web holes, which is still unresearched. Numerical simulations were conducted using the Abaqus finite element analysis software to study the elastic shear buckling response. Parametric studies were then performed, where a data pool was generated for CFS channels with no web holes, unstiffened web holes, and stiffened web holes, covering a range of parameters including web slenderness, web hole size, corner radius and edge stiffening element length. It was shown that edge stiffening of the web hole improves the shear buckling capacity compared to the CFS channels with no web holes and unstiffened web holes. New unified design proposals to estimate the elastic shear buckling strength of CFS channels with no web holes, unstiffened web holes, and edge stiffened web holes were developed based on the generated data. The new unified design proposals of modified shear buckling coefficient and equivalent thickness method offer accurate elastic shear buckling strength predictions.

Shear loading dominated damage mechanisms and strain localization studied by in situ 3D laminography imaging and Digital Volume Correlation for AA2198-T8

Damage and strain changes during shear dominated loading were assessed in situ via synchrotron laminography. In combination with digital volume correlation (DVC), local strain fields inside the material were determined thanks to the contrast provided by intermetallic particles. Testing was performed on a thin sheet sample with an optimized geometry that induced shear stress states in two ligaments opposite to each other with respect to the loading axis. Examining one of the ligaments, the strain fields in the material showed the expected localization in the shear plane with a central peak in shear strain. The Lode parameter fields associated with incremental strain measurements were determined for the analyzed zone and found to be close to zero. The total Hencky von Mises strain close to failure was measured in the material bulk and reached values between 0.6 and 0.7 for a DVC element length of 20μm. In the shear zone, damage onset in the form of grain-related elongated cracks and of voids nucleating on intermetallic particles was detected from about half of the maximum value of the equivalent strain to failure onward. Voids between particle clusters grew in shear as the particles were rigid and mostly brittle. Damage was mainly concentrated in the gage section subjected to shear and away from free surfaces, in particular away from the notches. It was characterized and quantified with respect to the maximum equivalent strain found inside the band.

Stability of antenna support belts

Introduction. The article deals with the issues of stability of compressed belts of lattice construction, as systems in the form of continuous rods consisting of panel elements. Currently, the estimated length of compressed elements is established by design standards for calculating stability without taking into account variability due to the influence of numerous random and systemic factors. This approach does not encourage the improvement of design solutions, the quality of their execution and the control of the structure. And most importantly, it does not allow to realize the reserves of the bearing capacity of structures laid down by the norms. The purpose of this study is to identify and substantiate the reserves of the bearing capacity of antenna supports of a lattice structure according to the criterion of stability of compressed belts.Materials and methods. It is shown that the values of the calculated length coefficient are set by norms with a margin, due, in particular, to ensuring the reliability of structural systems of compressible elements. It is proposed to consider the estimated length of compressed elements as a random variable. The problem of probabilistic estimation of the free (calculated) length of a centrally compressed element as a parameter of the critical force of loss of stability is solved. The possible normative and calculated values of the calculated length coefficient are given, ensuring the reliability of the calculation of compressed antenna support belts, adopted in the current design standards. To assess the variability of stability indicators, the task is to conduct experimental studies, in particular, with the measurement of vibration frequencies of full-scale structures. By controlling the variability indicators of the calculated length coefficient, it is possible to regulate not only reliability, but also the load-bearing capacity reserves provided for by design standards.Conclusions. The proposed approach to the calculation of stability allows to control the calculated values of the calculated length coefficient by controlling statistical variability (coefficient of variation). If there are available methods for measuring indicators, the approach described in the article to calculating compressed elements for stability can be an effective means and tool for improving design solutions, the quality of their execution and control of the structure.

Predicting the buckling behaviour of thin-walled structural elements using machine learning methods

The design process of thin-walled structural members is highly complex due to the possible occurrence of multiple instabilities. This research therefore aimed to develop machine learning algorithms to predict the buckling behaviour of thin-walled channel elements subjected to axial compression or bending. Feed-forward multi-layer Artificial Neural Networks (ANNs) were trained, in which the input variables comprised the cross-sectional dimensions and thickness, the presence/location of intermediate stiffeners, and the element length. The output data consisted of the elastic critical buckling load or moment, while also providing an immediate modal decomposition of the buckled shape into the traditionally defined ‘pure’ buckling mode categories (i.e. local, distortional and global buckling). The sample output for training was prepared using a combination of the Finite Strip Method (FSM) and the Equivalent Nodal Force Method (ENFM). The ANN models were subjected to a K-fold cross-validation technique and the hyperparameters were tuned using a grid search technique. The results indicated that the trained algorithms were capable of predicting the elastic critical buckling loads and carrying out the modal decomposition of the critical buckled shapes with an average accuracy (R2-value) of 98%. The influence of the various channel parameters on the output was assessed using the SHapley Additive exPlanations (SHAP) method.

Experimental Analysis of Channel Steel Member under Tension Load with Damage in the Unconnected Legs.

Damage occurring to steel element structures is highly possible due to tearing ruptures, corrosion, or the adoption of sudden loads. The damage has a great effect on their capacity to bear load and the corresponding elongation, as well as the distribution of the stresses in the cross-section of the element. Therefore, in the present research, experimental tests were carried out on 15 specimens of channel steel elements with different damage ratios in the unconnected legs and at different locations along the element's length. Through the test, the load and the corresponding elongation values were obtained for the control and damaged specimens. From the study of the different variables, it was demonstrated that the damage location does not significantly affect the load capacity, with a maximum difference of 1.9%. With the presence of the damage in only one leg at a ratio of less than or equal to 40%, the prediction of the value of the loss in the load is within the safe limit. However, if this ratio increases, there is a defect in calculating the loss in the load as it is greater than the effect of the damage. If there is any damage in the two legs of the channel together, the prediction of the loss of load is within the safe limit, where the loss is less than the effect of the damage ratio. We propose a model that can predict the capacitance of the axial load of steel channel elements through identifying the ratio of damage in the unconnected leg.

ALE-ANCF modeling of the lowering process of a J-lay pipeline coupled with dynamic positioning

A novel structural dynamics model for the lowering process of a J-lay pipeline is established by combining the absolute nodal coordinate formula with the arbitrary Lagrangian–Eulerian description. The constraint on the top of the pipeline is introduced into the dynamic equation in the form of generalized coordinates by using a material transport boundary to simulate the lowering process of the top end of the pipeline. A mesh scheme is adopted to control the element length and prevent numerical disturbances. The accuracy of the material transport boundary and mesh scheme is verified for the case of a pendulum with a time-varying length. Then, a coupled analysis program is developed to investigate J-lay deployment by a vessel using dynamic positioning. The tensioner is modeled as a damper to adjust the pay-out speed of the upper end of the pipeline. The numerical analysis is carried out on an explanatory example of a 16-inch pipeline being laid at a 1000-m water depth. The results show that the lowering process strongly affects the dynamic characteristics of the touch-down zone.

On the issue of dynamics of two-tier mechanical hydroponic installations with rigid load-bearing elements

Hydroponic green forage (HGF) is a high-quality ecological product containing a full range of required nutrients and vitamins. A two-tier hydroponic installation with rigid load-bearing elements has been developed at Kuban State Agrarian University named after I. T. Trubilin. The purpose of the research is to determine the strength and mass complex ratios that ensure stable dynamics of movement of all elements of the system during the operation of a two-tier hydroponic installation. The derivation and solution of differential equations of the dynamics of the elements of the installation is given. As a result of experimental studies, it is proved that the maximum deviation of the center of mass of the system, tray-crop-guides does not exceed 15 cm. Based on theoretical studies, the ratio of the parameters of the system under consideration was determined, in which there is no beating phenomenon. The lengths of the load-bearing elements should not be different, and the ratio of the weights of the loaded and free trays should vary within 0.15–0.25.

Fiber Bragg Gratings for Temperature Measurements Under Thermal Gradients: Comparison Between Two Different Lengths

In recent decades, fiber Bragg grating (FBG) sensors found widespread acceptance in several biomedical applications thanks to their indisputable advantages. Thermal ablation treatments (TATs) account for one of the fields where FBGs have gained large applicability for temperature measurements. The sensing element length can affect the accuracy of the FBG measurement in this application. A longer length provides a more prominent peak in the FBG reflected spectrum, resulting in a higher signal-to-noise ratio (SNR). A shorter FBG length implies a lower SNR but offers the benefits of better spatial resolution. Therefore, the choice of an adequate length can be crucial to minimize measurement errors, but the literature lacks exhaustive investigations on this parameter. The aim of our study is to supply additional knowledge about the effect of two different FBG lengths on temperature estimation in the presence of linear thermal gradients and with gradients mimicking the condition caused by TATs. In both cases, we compared the output of a 10-mm FBG with those of four FBGs 1 mm long, using a thermal camera as a reference instrument. Results suggest the better suitability of shorter sensors to retrieve thermal gradient information along their position instead of the longer FBG, which could lead to unacceptable measurement errors during TATs.

On the Effects of Driven Element L/D Ratio and Length in VHF-SHF Yagi-Uda Arrays

While the Yagi-Uda array has been studied for decades, one issue appears to have received less attention than perhaps it should, namely, the effects on performance of the array’s driven element length and its length-to-diameter ratio. This paper looks at that question. It shows that decreasing the L/D ratio increases impedance bandwidth, but it may shift the IBW band sufficiently far from the design frequency that other parameters such as gain and front-to-back ratio probably are adversely affected. It also shows that array performance is not relatively independent of element diameters. This paper also investigates the effect of lengthening the driven element, which can substantially improve IBW. Several iterations of a 3-element prototype and improved arrays are modeled with the Method of Moments and discussed in detail. A five step design procedure is recommended and applied to a Genetic Algorithm-optimized 3-element Yagi at 146 MHz. This array exhibits excellent performance in terms of gain, front-to-back ratio, and especially impedance bandwidth (nearly 14% for voltage standing wave ratio ≤ 2:1 with two frequencies at which 50 ? is almost perfectly matched). While the analysis and recommended design steps are applied to cylindrical array elements, which commonly are aluminum tubing for stand-alone VHF-SHF Yagis, they can be applied to other element geometries as well using equivalent cylindrical radii, for example, Printed Circuit Board traces for planar arrays. One consequence of lengthening the driven element while reducing its L/D ratio is that some reactance is introduced at the array feedpoint which must be tuned out, and two approaches for doing so are suggested.

Fuzzy Inverse Logic Method and Its Usage in the Design of Steel Truss System Elements Constructed with Steel Pipe Profiles

Bu çalışmada, yapay zekâ yöntemlerinden biri olan bulanık mantık yöntemi kullanılarak, çelik boru profillerin çekme ve basınç kuvveti etkisindeki kapasitelerini belirleyebilmek için iki adet bulanık model oluşturulmuştur. 2018 Türk Çelik yapılar Yönetmeliğinde belirtilen GKT yöntemine göre oluşturulan her iki bulanık modelde de, çelik sınıfı S355 olarak sabit olarak tutulurken, kesit çapı (D), profil et kalınlığı (t) ve eleman uzunluğu (L) değişken parametreler olarak dikkate alınmıştır. Eksenel çekme kapasitesi (Tn) ve eksenel basınç kapasitesi (Pn) ayrı ayrı olarak bu modellerin çıktı parametrelerini oluşturmuşlardır. Her iki modelin oluşturulmasında aynı girdi değişkenleri değerlerine sahip ancak çıktı parametreleri farklı olan 1400 ‘er adet örnek çözüm kullanılmıştır. Kullanılan bu örnek çözümlerin haricinde 988 ‘şer adet farklı örnek çözüm ile bu modeller test edilerek, sırasıyla maksimum % 2.764 ve maksimum % 4.076 hata ile eksenel çekme ve basınç dayanımlarının tahminde kullanılabilecekleri ortaya konulmuştur. Daha sonra geliştirilen bulanık modellere, bulanık ters mantık yöntemi 3 farklı izostatik düzlem kafes sistem örneği için uygulanarak bu kafes sistemleri oluşturan çubuk elemanların tasarımları gerçekleştirildikten sonra dayanım kontrolleri karşılaştırmalı olarak 2018 Türk Çelik yapılar Yönetmeliğinde belirtilen GKT yöntemi ile gerçekleştirilmiştir. Sonuç olarak, bulanık mantık ve bulanık ters mantık yöntemlerinin birlikte aynı sayısal veriyi kullanarak boru kesitli çelik kafes sistem elemanların kapasitelerinin belirlenmesinde ve aynı zamanda tasarımlarının gerçekleştirilmesinde model hataları da dikkate alınarak güvenle kullanılabilecekleri ortaya konulmuştur.

Modelling and design of low-power, non-conventional current sensors based on smart materials for high-voltage transmission lines

This paper presents a new technique for measurement of current based on magnetic shape memory (MSM) smart alloys. MSM alloys undergo shape changes when exposed to magnetic fields. The non-conventional instrument transformer (NCIT) proposed in this paper utilises this property to measure current. There is a correlation between the magnetic field produced by a current and the shape change of an MSM material (MSM sensor). By exploiting this correlation, we have shown that it is possible to measure alternating currents (a.c.) in high voltage overhead transmission lines. A change in the length of the MSM element causes voltage output in a linear variable differential transducer. The design of the NCIT was optimised for transmission lines. Several designs of its magnetic circuit were simulated using finite element package ANSYS APDL. Several key parameters were investigated to evaluate their effects on the sensitivity of the NCIT. Results are presented as the relationship between the current in the conductor and strain (linear elongation) of the MSM element. A commonly used conductor in high-voltage transmission lines was modelled together with the MSM element and the magnetic circuit. Recommendations have been made on the design of NCITs considering various parameters. In addition, analyses of errors in ANSYS models for the magnetic circuit have been presented. The developed methodology and obtained results are verified by comparing them to the results obtained through an experiment done by a manufacturer of MSM materials.

Agent-based modelling for early-stage optimization of spatial structures

Agent-based modelling (ABM) is a complex problem-solving approach that can be employed in early-stage parametric design, and certain design applications may benefit from such a bottom-up strategy. This research investigates the potential of ABM for structural design optimization. A case study of a form-found cantilevered truss is presented that has a doubly curved shape over a regular grid, resulting in individual members with different lengths across the structure. It is hypothesized that an agent-based approach might generate an irregular grid of similar or better structural performance, but with more uniform length of individual elements. This approach could be useful when designing a global structural form from a kit of parts or adaptively reusing a disassembled existing structure with regular member lengths. A series of ABM simulations are conducted with different hyperparameters, and the generated designs are compared to the original form-found shape in terms of structural performance.

PSSNet—An Accurate Super-Secondary Structure for Protein Segmentation

A super-secondary structure (SSS) is a spatially unique ensemble of secondary structural elements that determine the three-dimensional shape of a protein and its function, rendering SSSs attractive as folding cores. Understanding known types of SSSs is important for developing a deeper understanding of the mechanisms of protein folding. Here, we propose a universal PSSNet machine-learning method for SSS recognition and segmentation. For various types of SSS segmentation, this method uses key characteristics of SSS geometry, including the lengths of secondary structural elements and the distances between them, torsion angles, spatial positions of Cα atoms, and primary sequences. Using four types of SSSs (βαβ-unit, α-hairpin, β-hairpin, αα-corner), we showed that extensive SSS sets could be reliably selected from the Protein Data Bank and AlphaFold 2.0 database of protein structures.

Tunable Cross-Coupled metallic elements loaded epsilon negative and Near-Zero index characteristics based metamaterial

This study examines epsilon-negative (ENG) and near-zero index (NZI) tunable cross-coupled (TCC) metamaterial (MTM) unit cells for multi-band wireless communications. The square split ring resonator (SSRR), a cross-coupled metallic element, and a star-like shape are added at the center of the resonator. The EMR value is 10.24, representing the proposed structure's compactness. The tunability characteristics are investigated by varying the cross-coupled nearby metallic element length within the frequencies of 3.38–3.44 GHz, 7.53–8.0 GHz, and 10.24–10.79 GHz. The NZI characteristics are observed within the frequencies of 3.40–4.66 GHz, 7.41–7.75 GHz, and 10.17–10.31 GHz, respectively, while the ENG characteristics are observed at 2.61–5.15 GHz, 6.43–8.23 GHz, and 9.28–10.45 GHz, respectively. The bandwidth of the designed TCC MTM unit cell is 2.49–4.00 GHz, 6.89–7.83 GHz, and 9.75–10.64 GHz, respectively. The tunability, ENG, and NZI characteristics with a high EMR value enable it for critical microwave applications, including S, C, and X frequency bands. The anticipated structure may be a good candidate for enhancing the gain and bandwidth of the antenna and filter designs and operations, as well as frequency stability and efficiency for multi-band wireless communications.

Enhanced moving finite element method based on error geometric estimation for simultaneous trajectory optimization

The direct method has been widely used in various fields of trajectory optimization due to the need to optimize the performance of a controlled dynamic system. An essential issue in the development of the direct method is the selection of the finite element mesh. Although there have been many pieces of research on adaptive mesh refinement, few works focused on finite element layout optimization before the refinement. This paper proposes an enhanced moving finite element method (EMFE), taking the length of each finite element as a variable, based on the geometric estimation of non-collocation-point error (NCPE) and generalized finite element length (GFEL). The features of EMFE include flexible problem reformulation, stable numerical calculation and the ability to locate breakpoints for singular control problems (the control variables appear linearly in the problems) and finding the local minimum numerical error. The theoretical basis of the ability to locate the breakpoints for singular control problems and the feature of NCPE estimate has also been investigated. Three numerical examples, two of which are singular control problems for lunar landing and the other is a multi-phase nonlinear problem for launch vehicles, demonstrated the performance and features of the proposed EMFE method.

Comparative wood anatomy of 16 Malagasy Dalbergia species (Fabaceae) using multivariate techniques

Summary Rosewood and palisander (Dalbergia L.f., Fabaceae) are sources of highly valuable tropical timber and include species threatened by habitat degradation and selective logging for national and international trade. Law enforcement depends on reliable and cost-effective species-level identification of timber along the supply chain. The potential of wood anatomy to distinguish between species has not yet been systematically investigated for Dalbergia species from Madagascar. We assessed 36 qualitative and eight quantitative wood anatomical features in 16 Malagasy Dalbergia species that form medium-sized to large trees, representing each species by at least five individuals. We integrated and contrasted the newly collected data with existing data from InsideWood and two previous studies. Principal component analysis of 93 individuals and 29 variables resulted in non-overlapping hulls for eight species with respect to the first two dimensions. Four quantitative features (number of ray tiers per millimetre, number of rays per millimetre, vessel density, and vessel element length) and two qualitative features (scanty paratracheal axial parenchyma and irregular to absent storied structure) were found to be potentially diagnostic to distinguish three single species and three pairs of closely related species. Following our analyses, we provide a provisional microscopic wood anatomical identification key for the 16 Dalbergia species, which can be applied to both logs and sawn wood.