Element Level Research Articles

Topology optimization of multimaterial distribution based on isogeometric boundary element and piecewise constant level set method

Based on isogeometric boundary element method (IGA BEM) and piecewise constant level set (PCLS) method, a new topology optimization approach is proposed to design the distribution of sound absorbing materials (SAMs) on structural surfaces. First, an efficient IGA BEM is developed with the combination of multipatch discretization and parallel CPU design. A complex submarine model comprising multiple non-uniform rational B-spline surfaces is built for engineering optimization design. Second, the PCLS method is applied to represent the multiple SAM domains without gray elements, and the sensitivities of the objective function with respect to PCLS functions are obtained using the adjoint variable method. Finally, the optimization algorithm based on PCLS method is improved by a novel penalty coefficient formulation and ordered volume constraints. The improved optimization algorithm can realize the control of multimaterial volume fractions and make the objective function steadily converge for different volume structures without the need to change any parameters. The accuracy, efficiency, and applicability of the proposed approach in engineering are demonstrated by several numerical examples.

IMPLEMENTASI PERATURAN DAERAH KOTA PALANGKA RAYA NOMOR 11 TAHUN 2017 TENTANG RENCANA INDUK PEMBANGUNAN KEPARIWISATAAN KOTA PALANGKA RAYA TAHUN 2017-2028

This study aims to find out and examine the implementation of the development of tourism in the city of Palangka Raya and also to find out what the benefits of tourism development for the community.The author uses the theories of Donald Van Metter and Carl Van Horn which are influenced by six indicators, namely the Size and Objectives of Policies, Resources, Characteristics of Implementing Agents, Attitudes / Dispositions of Implementers, Communication between Organizations and Implementing Activities, and Economic, Social and Environmental Political. This study used qualitative research methods. Data taken based on information from informants at the element level of the Head of Tourism, Attractiveness Management Section in the City Culture and Tourism Office of Palangka Raya and the Community and data obtained through the results of field research. Data announcement techniques in the form of observations and interviews.The results showed that the Culture and Tourism Office had implemented Palangka Raya City Regulation No. 11 of 2017 concerning the Master Plan for the Development of Tourism in Palangka Raya 2017-2028 quite well. Given that this development is a long-term nature, the government prioritizes development at several points that have the highest tourism potential, but the Culture and Tourism Office still lacks Human Resources with a tourism background to improve their performance. The benefits of tourism development felt by the people of Palangka Raya city are seen from several aspects, namely economic aspects, social and cultural aspects, environmental aspects, aspects of social values and science as well as aspects of opportunities and employment opportunities.

Construction Strategic Project Readiness Assessment

Proper use of construction strategic management consists of strategic planning for controlling the implementation of strategies during front-end planning (FEP). To improve FEP effort, industry best practice instrument, i.e., Project Definition Rating Index (PDRI) has been used to ensure continued alignment and focus on strategic project priorities. This study proposes a methodology for creating a SWOT (strengths, weaknesses, opportunities, and threats) analysis of big post-mining data from organizations that have implemented PDRI, as a standardized tool used across capital project portfolios. The results show that the proposed methodology has the potential to improve project success when applied as a benchmark of baseline conditions, the element level.

Lumped-Parameter Equivalent Circuit Modeling of CMUT Array Elements

Design and modeling are key steps in the value chain of Capacitive Micromachined Ultrasonic Transducer (CMUT) arrays. Although CMUT array element models are very powerful, most of them are still limited in their use as tools for electronic design assistance. The electroacoustic equivalent circuits developed are mainly based on a distributed-element approach while lumped-parameter electrical circuits are better suited for electronic software design tools interoperations. To meet this need, the present study aims to implement an electroacoustic equivalent scheme of a full array element, based on a two-port network representation made of lumped-parameters. After an extensive bibliographical review of CMUT models, the new model is set-up from a fully distributed approach using Foldy’s electroacoustic definitions at the element level. Transmit and receive modes are implemented using scalar equations given by the lumped parameters. Moreover, based on a reciprocity analysis, the performance of the complete measurement chain in emission and reception will be defined using the relevant transfer functions. Finally, to help one design CMUT array elements for a given application, a method based on the computation of membranes thickness-size master curves is proposed. The two-port network representation of a full CMUT-based array element allowed by the new lumped-parameter modeling opens a wide range of possibilities regarding array design, electronic integration, operations with acoustic propagation simulation tools and more.

Comparison of electronic versus manual abstraction for 2 standardized perinatal care measures.

Given that electronic clinical quality measures (eCQMs) are playing a central role in quality improvement applications nationwide, a stronger evidence base demonstrating their reliability is critically needed. To assess the reliability of electronic health record-extracted data elements and measure results for the Elective Delivery and Exclusive Breast Milk Feeding measures (vs manual abstraction) among a national sample of US acute care hospitals, as well as common sources of discrepancies and change over time. eCQM and chart-abstracted data for the same patients were matched and compared at the data element and measure level for hospitals submitting both sources of data to The Joint Commission between 2017 and 2019. Sensitivity, specificity, and kappa statistics were used to assess reliability. Although eCQM denominator reliability had moderate to substantial agreement for both measures and both improved over time (Elective Delivery: kappa = 0.59 [95% confidence interval (CI), 0.58-0.61] in 2017 and 0.84 [95% CI, 083-0.85] in 2019; Exclusive Breast Milk Feeding: kappa = 0.58 [95% CI, 0.54-0.62] in 2017 and 0.70 [95% CI, 0.67-0.73] in 2019), the numerator status reliability was poor for Elective Delivery (kappa = 0.08 [95% CI, 0.03-0.12] in 2017 and 0.10 [95% CI, 0.05-0.15] in 2019) but near perfect for Exclusive Breast Milk Feeding (kappa = 0.85 [0.83, 0.87] in 2017 and 0.84 [0.83, 0.85] in 2019). The failure of the eCQM to accurately capture estimated gestational age, conditions possibly justifying elective delivery, active labor, and medical induction were the main reasons for the discrepancies. Although eCQM denominator reliability for the Elective Delivery and Exclusive Breast Milk Feeding measures had moderate agreement when compared to medical record review, the numerator status reliability was poor for Elective Delivery, but near perfect for Exclusive Breast Milk Feeding. Improvements in eCQM data capture of some key data elements would greatly improve the reliability.

An adaptive isogeometric shell element for the prediction of initiation and growth of multiple delaminations in curved composite structures

In order to model prominent failure modes experienced by multi-layered composites, a fine through-thickness discretisation is needed. If the structure also has large in-plane dimensions, the computational cost of the model becomes large. In light of this, we propose an adaptive isogeometric continuum shell element for the analysis of multi-layered structures. The key is a flexible and efficient method for controlling the continuity of the out-of-plane approximation, such that fine detail is only applied in areas of the structure where it is required. We demonstrate how so-called knot insertion can be utilised to automatise an adaptive refinement of the shell model at arbitrary interfaces, thereby making it possible to model multiple initiation and growth of delaminations. Furthermore, we also demonstrate that the higher-order continuity of the spline-based approximations allows for an accurate recovery of transverse stresses on the element level, even for doubly-curved laminates under general load. With this stress recovery method, critical areas of the simulated structures can be identified, and new refinements (cracks) can be introduced accordingly. In a concluding numerical example of a cantilever beam with two initial cracks, we demonstrate that the results obtained with the adaptive isogeometric shell element show good correlation with experimental data.

Efficient numerical treatment of a gradient damage model for materials undergoing large deformations

AbstractIn this contribution we present a gradient damage formulation (cf. [1]) for hyperelastic materials undergoing large deformations, which is based on the small strain formulation of [2]. Through discretizing the gradient extended damage field with the neighbored element method the damage update can be performed at the element level. Although local update iterations remain present, the global system of equations goes without any additional degrees of freedom compared to purely elastic computations. Furthermore, in the case of severely damaged material, an element erosion based stabilization technique is considered. Computing efficiency and numerical robustness is demonstrated in several numerical examples.

Toxicity of coal fly ash and coal gangue leachate to Daphnia magna: Focusing on typical heavy metals

To identify potential toxicity of heavy metals (HMs) in coal fly ash (FA) and coal gangue (CG), this study measured Cd, Cr, Cu, Zn, Pb and Ni in two FAs and two CGs, and assessed their leachates' toxicity to Daphnia magna (D. magna). The results showed that the selected HMs in material and their leachates were low. However, under simplified Elendt M7 medium exposure system, the added leachates inhibited the survival and reproduction of D. magna. The HMs in D. magna increased as leachate increased, and D. magna mortality increased as the HMs in D. magna increased overall. The Cr and Ni in D. magna both showed significant linear positive correlation with the mortality. These indicated that HMs in leachate dilutions were important reason to inhibit D. magna. Moreover, the HMs in leachate also changed the biomarkers and caused oxidative stress in D. magna. Antioxidant system and cell structure of D. magna were further destroyed as leachates increased. The leachates’ inhabitation (mortality and living offspring) to D. magna depended on the properties of FA and CG, and the chemical composition of their leachates. Element level (e.g., C, S and N) and their chemical speciation (e.g., S2− and NH4+) likely impacted the leaching rate and toxicity of HMs.

Comparison of Forwarder Productivity and Optimal Road Density in Thinning and Clearcutting of Pine Plantation in Southern Brazil

The prescription of forest management determines the number of trees to be cut and, consequently, the harvested wood volume, which directly influences the forest operations dynamic. The objectives of this paper were (i) to analyze the effect of process factors on wood extraction performance with forwarder in first thinning and clearcutting of Pinus taeda L. plantations; and (ii) to economically determine the optimal road density to manage these plantations. Time and motion studies at the cycle element level were conducted to quantify and model the time consumption, productivity, and operational costs of the extraction. The optimal road density (ORD) for both operation types (OT) was determined based on the transport geometry model, considering the minimization of the sum of unitary costs with construction and maintenance of roads, loss of productive area, and wood extraction. The extraction distance (ED), slope (SL), average log volume (LV), and OT had a significant effect on the time consumed in travels, and therefore, on productivity (PPMH). In clearcutting, the average PPMH was 12.17 m3ob PMH0-1, while, in thinning, it was 10.94 m3ob PMH0-1; however, as the ED increased, the difference of PPMH and the cost of extraction between the operations decreased, which highlighted a greater effect of this factor on forwarder’s work in clearcutting. For this reason, the ORD for clearcutting (37.76 m ha-1) was higher than for thinning (27.84 m ha-1). Therefore, we demonstrated in this study that the type of operation and forest management regime, as well as their interaction with process factors, affect the sizing of the number of roads per unit area, and also the costs of the forest activity.

Nonlinear dynamic response analysis of buildings for wind loads. A new frontier in the structural wind engineering

The structural engineering practitioners often deal with natural hazards that generate a structural response that is dynamic in nature. The wind loads are long duration load types and their induced effects, especially for severe events, need to be predicted through analysis by efficient numerical nonlinear solvers. In this paper the nonlinear wind-induced effects on structures are predicted using a non-commercial software based on the 3D Force Analogy Method (3D-FAM). The wind loads consist of time-histories of pressure coefficients recorded at a large number of taps in the wind tunnel test for a model corresponding to an 80 m high prototype building. A considerable number of dynamic nonlinear analyses are performed for different mean hourly wind speeds and wind blowing directions. For each case, the inelastic behavior of building is monitored through and efficient complementary energy balance-based analysis and quantified in time-domain by damage indices at each section, element, story and structural level.

Homogenization and locality of landscape characteristics in the waterfront space based on geotagged photographs

AbstractThe urban landscape reveals the relationship between the natural evolution process and artificial intervention force in the watershed system and also represents the most direct reflection of man–land relationships in watersheds. However, the homogeneity of modern urban functions affects the expression of cultural atmospheres. As a result, quantitative and qualitative analyses of the landscape homogenization level are of great significance for considering local culture in landscape planning according to locality conditions. In this study, open geotagged photographs were assessed to determine the landscape changes and differences in the Yangtze River Basin and the spatial characteristics of locality elements in order to identify the relationship between landscape locality and urbanization. The results indicate that the landscape element level changes gradually downstream of the Yangtze River and with increasing distance from the river bank. The closer the city to the lower reaches of the Yangtze River, the less dominant the main landscape element of the city. Several landscape elements were significantly agglomerated in space, and this agglomeration distribution was attributed to the degree of urbanization.

Metals contamination and trace element level in breast milk samples of mothers in Kenitra, Morocco

ABSTRACT The current study aimed to examine the quality of breast milk in Kenitra city (Morocco), regarding its levels of essential elements Iron (Fe), Copper (Cu), and Zinc (Zn) and heavy metals chromium (Cr), lead (Pb), and cadmium (Cd), besides carried out the inter-element correlation and investigated their association with some sociodemographic parameters of lactating women. For this, a total of 95 (n = 95) samples of breast milk were collected, at the second postpartum month from mothers in five governmental health care centres in Kenitra. After total mineralisation, human milk sample analysis was conducted by using flame atomic absorption spectrophotometry (AAS) for the essential elements detection, and heavy metal quantification was performed by using the atomic absorption spectrophotometer with a graphite furnace. Mean levels of Fe, Cu and Zn were 0.43, 0.26 and 6.11 mg/L, while the main concentrations of Cr, Pb and Cd were 8.84, 3.20 and 0.60 µg/L, respectively. Statistical analysis had proved a highly significant correlation between surveyed elements, especially between Cu and Zn, Pb and Cd, besides the strong relationship between the essential elements mentioned before and the heavy metals. Moreover, breast milk elements are most affected by sociodemographic parameters, principally the body mass index (BMI) of mothers, dietary habits and newborn gender. Moreover, 6.46% and 27.37% of samples are exceeded the recommended limits for Cd and Pb, respectively, which verify the low contamination of surveyed breast milk samples. Whereas, the mean values of Cr and Zn were above the limits recommended by the word human organisation, but so far there are no reports of adverse effects on newborns at those reported doses. These data justify the requirement to set surveillance policies by health organisations with the purpose of limit maternal and foetal exposure to heavy metals and strengthen health education.

Time-domain analysis of framed structures based on “exact” structural-property matrices for nonprismatic Timoshenko’s elements

This paper applies a unified process to calculate ”exact” (consistent) finite-element (FE) matrices for framed structures having nonprismatic elements and including shear-deformation and rotational-inertia effects. In this process, the exact expressions for the element stiffness and nodal-load coefficients result from applying the principle of virtual forces (PVF) at the element level. Rigidity values, determined at a certain number of cross sections in the frame element, are employed to describe how the corresponding rigidities vary along its length. For that, interpolation polynomials of different orders are considered. Exact Timoshenko’s shape functions, built under the most general cases of rigidity variation, are used for evaluating the mass matrix coefficients. In the applications, complex 2D frames with nonprismatic elements are considered to simulate bridge structures under seismic excitation and a generic harmonic load. Comparisons with highly accurate response time-histories obtained by employing ANSYS (3D) solid-FE models are effected to verify the robustness of the proposed formulation.

An equilibrium‐based formulation with nonlinear configuration dependent interpolation for geometrically exact 3D beams

AbstractThis article describes a novel equilibrium‐based geometrically exact beam finite element formulation. First, the spatial position and rotation fields are interpolated by nonlinear configuration‐dependent functions that enforce constant strains along the element axis, completely eliminating locking phenomena. Then, the resulting kinematic fields are used to interpolate the spatial sections force and moment fields in order to fulfill equilibrium exactly in the deformed configuration. The internal variables are explicitly solved at the element level and closed‐form expressions for the internal force vector and tangent stiffness matrix are obtained, allowing for explicit computation, without numerical integration. The objectivity and absence of locking are verified and some important numerical and theoretical aspects leading to a computationally efficient strategy are highlighted and discussed. The proposed formulation is successfully tested in several numerical application examples.

Elastic Analysis of Steel-Concrete Composite Beams with Partial Interaction

The paper presents an exact analytical method for the elastic analysis of steel-concrete composite beams with partial interaction. Accepting the basic assumptions of the Newmark analytical model and adopting the axial force in the concrete slab as the main unknown, the second order nonhomogeneous differential equation of the steel-concrete composite element with partial interaction is derived. Further, the complete solutions for simply supported and fixed-ended composite beams subjected to concentrated and uniform loads respectively, are developed. The solution of the homogeneous equation is determined by imposing proper Dirichlet or Neumann boundary conditions depending on the static scheme of the element. The particular solutions are then derived for the considered loading conditions. It is shown that the internal axial force in concrete slab associated to composite beams with partial interaction can be expressed as a fraction of the axial force in concrete slab under full interaction through a non-dimensional function f(aL) which takes into account the connection’s stiffness, the mechanical properties and also the length of the element. Moreover, the solutions are included in a flexibility-based approach to derive the force-displacement relations of the beam element with partial interaction. For the resulted 2-noded beam-column element with 6DOF, the stiffness matrix is derived, showing that the partial composite action may be included at the element level by means of a series of correction factors applied to the standard full-interaction stiffness matrix coefficients. A numerical example is provided to demonstrate the accuracy and performance of the proposed method. Within the elastic range, the predicted load-midspan deflection curve is in very good agreement with both experimental and other numerical results retrieved from international literature. A parametric study was conducted to investigate the influence of the shear connection degree on the beam’s midspan deflection and the results were compared with those computed by using code provisions.

Performance evaluation of a RC frame structure from element level to structure level

Ductility is an important design parameter which controls the flow of plasticity in a structure to improve the ability to sustain severe load with nonlinear deformation. In the present study, the flow of ductility from element level to structure level has been assessed. For the study purpose, a RC frame structure has been considered and the displacement ductility capacity of the frame has been evaluated from the best possible combinations of curvature and rotation ductility capacity of beams and columns. To generate the capacity curve of the structure, nonlinear static pushover analysis has been performed. It has been observed that the variation of section ductility of the column is more significant with diameter and spacing of the transverse reinforcement bar than the same for beam section. A reduction of structural ductility has been observed as compared to the element ductility which needs more detailing requirement for the fulfillment.

Performance of a whole tree mechanised timber harvesting system when clear-felling a 32-year-old Pinus taeda L. stand

Background: Work studies are fundamental for the development and assessment of timber harvesting systems aimed at rationalising and improving forest management activities. Methods: This study evaluated the operational performance of a mechanised whole-tree harvesting system in 32-year-old Pinus taeda L. stands producing multiple timber products. A time and motion study at the cycle element level was conducted to evaluate the operational performance of each component of the harvesting system. Equations were developed to estimate the productivity of tree extraction activity with a wheeled skidder and log loading with a mechanical loader. Results: Tree felling with an excavator-based harvester had the highest mean productivity (135 m3 per productive machine hour), followed by tree extraction with a wheeled skidder (117 m3 per productive machine hour), while manually processing larger logs with a chainsaw had the lowest productivity (25.7 m3 per productive machine hour). Operator, extraction distance and mean log volume had a significant effect on the performance of different activities and were included in productivity models. Conclusions: Operational performance of equipment was variable and dependent on the effect of the operator, extraction distance and log volume. Thus, the use of models to estimate productivity considering such factors, coupled with reduced delays to increase utilisation of equipment, will contribute to the better management and planning of forest harvesting operations under the evaluated conditions.

Model and method for representing complex dynamic information objects based on LMS-trees in NoSQL databases

The article analyzes the existing approaches to the description of large dynamic information objects in the construction of Automated control systems. Introduced and defined the concept of a ComplexDynamical Information Object. A comparative analysis of the temporal complexities of tree-like structures is carried out and the optimal one for working with ComplexDynamical Information Objectis selected. Most modern automated control systems use various approaches to describe automation objects for their operation. Under the automation object, we mean functional objects that are described in the form of structural models that reflect the properties of physical objects. Thus, for optimal work with complex dynamic information objects, we have developed our own model and method for describing the LMS-tree (Log-structured merge-tree), with the ability to split and store down to elementary levels. One of the features of our approach to describing objects is the presence of tree-like levels -the so-called “leaves”, by which we mean special tree elements that expand the description of the tree structure of a particular tree level. The minimal elements of the leaves of the tree –“veins”-are details, that is, elementary information elements. A leaf is a combination of “veins”(details) according to certain characteristics, which provide extended information about the level of the tree object. An atomic-level descriptor is a multiple NoSQL database field (array) where the tree level number is the index of the database array. This approach allows you to retrieve and group objects according to the element level of the tree definition.

Development of a circularity assessment method for facade systems

Various authorities identify the circular building strategy as the best way to reduce the environmental impact of the building sector. The EURECA project aims to develop a circular facade system for the renovation of high-rise buildings. The circularity of the facade systems proposed within the project should be evaluated in an objective manner. Current circularity assessment methods exist, however, they appear unfit to evaluate facade systems at an early design stage. Based on the analysis of existing assessment methods a new circularity assessment method is developed. The developed method allows to measure the circularity on element level with a limited amount of required information, allowing early stage decision-making. The method considers the parameters recycling, environmental cost, expected service life, component dependency, layer dependency and flexibility for reuse. The method is tested on four facade renovation systems: standard ETICS, circular ETICS, ventilated facade with rigid insulation and ventilated facade with flexible insulation. The circularity of each system can be represented by a radar chart, giving the score per parameter, or by a single score. In addition to the circular aspect, the financial aspect is added in the evaluation of the facade systems by using the Pareto front method.

Environmental Life Cycle Assessment scenarios for a district heating network. An Italian case study

District heating networks have present and future great potential in decarbonization and in general for improving the environmental profile of the European building sector. It is due to the integration of solar-thermal energy and other renewable sources, flexibility by thermal storage, and mainly the ability to recover industrial and municipal waste heat: providing benefits at the element (energy system) and city level. However, individual appliances, such as electric-driven heat pumps, are and will be an attractive option; the decarbonization process of the European electricity grid makes them very appealing from an environmental perspective (from an energy system viewpoint). In this paper, the authors investigate the environmental competitiveness of a district heating network to provide space heating and domestic hot water using the Life Cycle Assessment method. The evaluation was carried out for a new building area (approx. 26 500 m2 of net surface) located in Milan. The present and future (2030) environmental profiles of North Milan’s district heating network were assessed and compared with three individual electric-driven heat pumps (groundwater-source and 450 kW capacity each), as an alternative energy system. 16 potential impact categories were evaluated using, 1 kWh of thermal energy as a functional unit, ecoinvent as background database, and the Environmental Footprint 3.0 as impact assessment method. The results indicated that despite the higher CO2eq emissions compared to the heat pumps (208 vs 118 gCO2eq/kWhth), district heating could potentially have an almost equivalent climate change impact in the future, due to the integration of renewables sources, feasible with the 4th generation. The value of district heating and electric-driven heat pumps were 89 and 81 gCO2eq/kWhth, respectively for 2030. In contrast, the weighting results showed a better environmental profile for the district heating in both scenarios, allowing a reduction of 67% (in the present) and 19% (in the future).