Analysis and Optimization of Truss Structures, Constrained Handling using Genetic Algorithm

Multilocus variable number tandem repeat analysis (MLVA) utilizes short DNA repeat polymorphism in genomes, which is termed variable number tandem repeat (VNTR), to differentiate closely related organisms. One research challenge is to find an optimal set of VNTR to distinguish different members accurately. An intuitive method is to use an exhaustive search method. However, this method is not an efficient way to find optimal solutions from a dataset comprising many attributes (loci) due to the curse of dimensionality. In this study, metaheuristic methods are proposed to find an optimal set of loci combination. Basic genetic algorithm (BGA) and modified genetic algorithm (MGA) were proposed in our previous work for this purpose. However, they require prior knowledge from an experienced user to specify the minimum number of loci for achieving good results. To impose no such expertise requirement for parameter setting, a GA with Duplicates (GAD), which allows the inclusion of duplicated loci in a chromosome (potential solution) during the search process, is developed. The study also investigates the search performance of a hybrid metaheuristic method, namely quantum-inspired differential evolution (QDE). Hunter-Gaston Discriminatory Index (HGDI) is used to indicate the discriminatory power of a loci combination. Two Mycobacterium tuberculosis MLVA datasets obtained from a public portal and a local laboratory respectively, are used. The results obtained by using exhaustive search and metaheuristic methods are first compared, followed by a performance comparison among BGA, MGA, GAD, and QDE by a statistical approach. The best-performing GA method (i.e., GAD) and QDE are selected for a performance comparison with several recent metaheuristic methods using both MLVA datasets by a statistical approach. The statistical results show that both GAD and QDE could achieve higher HGDI than the recent methods using a small but informative set of loci combination.

The scientific article is devoted to a complex study of the stress-strain state of a monolithic slab, implemented using the author’s method of hydrostatic loading, which involves setting the load by the weight of water and regulating its value by the height of the water column. To implement the given procedure, we used a tank-shaped facility for field tests of structures for vertical short-term and long-term loads. To determine the deflections of the loaded slab system, we installed mechanical deflection gauges of the 6PAO brand under the slab at pre-planned places. The short-term loading of the selected section of the monolithic reinforced concrete slab involved three stages. The first two stages of loading were carried out step by step, with a load step of 1–2 kN/m2 and a time delay until the arrows of the deflection gauges stopped. The maximum load on the slab was 5 kN/m2. The maximum deflection was recorded for point 2 (conventional centre of the tank) and was equal to 1.27 mm. The third stage of slab loading proceeded by analogy with the previous two. The maximum load on the slab was 8 kN/m2. The maximum deflection was recorded for point 2 and equalled 1.57 mm. After completing the stepped loading, the water tank was left on the slab to track vertical deflections for 32 days. The study experimentally established that the displacement of the examined slab in the span and support zones under increased load did not exceed the normative values. We carried out numerical verification using finite-element modelling followed by calculations in a linear and non-linear model. The theoretical and experimental calculation results showed a qualitative and quantitative data match (the difference did not exceed 15–20%). The nature of the change in the deflections remained practically linear and closely correlated with the experimental data (the values of the maximum deflections were equal to 1.16 and 1.57 mm, respectively, which was less than the maximum allowable deflection of 30 mm). Based on the results of the comprehensive study, we have made proposals for further safe operation of the investigated slab system through the use of lightweight floor elements (lighter filling, reduction of screed thickness, and others) to limit the total load on the overlapping to 10 kN/m2 (taking into account dead weight of the slab, load from floor structure and partitions, load from people and various types of construction and other equipment). Keywords: hydrostatic loading, testing, concrete, calculation, deflection, modelling.

The objective of this paper is to optimize the amount of spare capacity reserved for the backup virtual paths (BVPs) in multicast asynchronous transfer mode networks. In this paper, we study the capacity and routing assignment problem arising in the design of self-healing networks using the VP concept. A major contribution of this work is to apply a genetic algorithm (GA) to the backup path search process instead of the trivial exhaustive search method. Experimental results indicate that both approaches have very comparable results in finding the multicast backup paths. Further, it also indicated that using a GA approach has a number of advantages over the exhaustive search approach, such as the computational requirement for a GA in finding good BVPs is small when compared to the exhaustive search method. A major drawback of our approach is that we cannot guarantee the finding of global optimum in real time.

Implementing a quality assurance (QA) process for compaction of aggregates using light weight deflectometer (LWD) requires construction of a 100 ft. long, 24 ft. wide test section prior to other uses. However, there are numerous cases where aggregates are used in construction of subgrade, subbase course, and base course in small areas, such as bridge approach, lane widening, patching, and shoulders, and construction of a test section is not possible. In addition, there are over 70 LWDs currently used in construction projects by Indiana Department of Transportation (INDOT). Maintaining a quality control process requires timely and appropriate calibration and verification of the LWD devices. This study performed intensive laboratory experiments on the aggregate materials commonly used by INDOT to determine the target deflection values for compaction QA and evaluate the effects of the moisture content and the interface condition of the inner wall of the Proctor mold on LWD test results. Intensive experiments were also performed in the test pits with LWD to determine the effect of the thickness of aggregate layer and close the gap between the LWD measurements made in-situ and in the Proctor mold. Extensive field LWD testing was conducted during construction of many projects in 2016 and 2017 to validate the compaction of various types of projects. Statistical tests were performed on historical compaction QA data from LWD testing and LWD verification data. It was concluded that moisture content has a significant effect on LWD deflection or modulus. Unbound aggregates compacted near the optimum moisture are capable of providing a stable modulus value when becoming wet and experiencing dramatic gains in modulus with decreasing the moisture content. Maximum allowable deflections were developed for QA of aggregate compaction, particularly in small areas. It was also found that annual verification is necessary to ensure repeatability of LWD deflection measurements. Recommendations were made for immediate and future implementations, such as improvement of the current field practice of compaction QA with LWD in terms of test frequency, test position, and moisture content test. Finally, it was recognized that urgent effort is needed to determine the optimum interval for LWD calibration and necessary training is needed to further improve compaction quality and consistency of compaction QA with LWD.

Truss structures are widely employed in the industrialized world. They appear as bridges, towers, roof supports, building exoskeletons or high technology light space structures. This paper investigates the simultaneous size, geometry and topology optimization of real life large truss structures using Genetic Algorithms (GAs) as optimizer and Finite Element Method as analyzer. In general the large truss structures are constructed from the duplication of some basic modules called bays. Thus, the final optimum design may be reached by optimizing the characteristics of the basic bays instead of optimizing the whole structure. Both single and multi-objective functions based on the mass of the structure and the maximum nodal displacement, have been considered as the cost functions. In order to have realistic optimal designs, the cross-sectional areas have been extracted from the standard profiles according to AISC codes and practical conditions are imposed to the bays. The design optimization problem is also constrained by the maximum stress, maximum slenderness ratio and the maximum and minimum cross-sectional area of the truss members. To accommodate all these constraints, two different penalty functions are proposed. The first penalty function considers the normalization of violated constraints with respect to the allowable stress or slenderness ratio. The second penalty function is a constant function, which is used to penalize the violations of the slenderness ratio. Two illustrative examples of realistic planar and space truss structures have been optimized to demonstrate the effectiveness of the proposed methodology.

One of the challenging engineering aspects of the new Cowboys Stadium in Arlington, Texas was design of foundations for the retractable roof arches. The two arches, with a clear span of approximately 393 m (1,290 ft), produce a lateral thrust of approximately 86,740 kN (19,500 kips) at each foundation with the lateral thrust line 32 degrees from horizontal. Design criteria included a maximum allowable deflection of approximately 12 mm (0.5 inches) for the foundations. Adding to the complexity was the varying geologic conditions with dense sand being predominant at one end of the arches and sandy shale being predominant at the other. Initial options considered by the design and construction teams included large mat foundations oriented perpendicular to the line of thrust of the arches, horizontal mat foundations with tie-down anchors, both vertical and battered drilled shaft groups, and battered micropile groups with both tension and compression elements. These options were determined to be problematic due to excessive deflection and/or constructability issues. Subsequently, the geotechnical design team proposed a foundation system consisting of slurry-placed diaphragm walls. This option resulted in a foundation system that is completely in compression without tension elements and provided a much stiffer system that could meet the deflection criteria. Preliminary dimensions of the diaphragm wall foundations were established based upon soil strength data obtained from field and laboratory testing. Final dimensions were confirmed based on instrumented load testing of two full-depth sacrificial diaphragm wall panels installed and tested prior to final design.

This paper presents a parametric study aimed at uncovering general design principles that govern the structural performance of honeycomb-type rigidified inflatable structures (RIS) as load-bearing wall systems for use in residential housing. This study involves the use of finite element modeling and optimization. A series of honeycomb-type RIS wall systems, each comprising different honeycomb cell sizes, are examined. The problem at hand is stated in the form of minimizing material volume subject to: permissible stress, maximum allowable deflection, and membrane thickness. The optimization results help identify optimal design configurations for given sets of loading conditions and material properties. The effects of various design parameters, such as cell size, material properties, and membrane thicknesses, are discussed. The performance of honeycomb-type RIS wall systems is compared with that of rectilinear-type RIS wall systems, which were studied previously. The work presented makes a significant step in establishing the feasibility of RIS for housing applications.

This study focused on improving light weight deflectometer (LWD) testing protocols and understanding material and equipment variability. The Indiana Department of Transportation (INDOT) adopted the LWD test for its efficiency and effectiveness in measuring soil stiffness, a crucial parameter for pavement structural layers. However, challenges remain for implementing LWD testing, particularly in small construction areas. There are also challenges with establishing standardized performance-related criteria for various subgrade treatments. To address these obstacles, this research aimed to develop maximum allowable deflections for compaction quality assurance without relying on site-specific test sections. A large-scale laboratory testing facility was established at the INDOT research center and equipped with advanced sensing systems and a sandbox for controlled testing environments. Finite element (FE) models simulate material behavior under LWD testing conditions by using the viscoelastic plastic model to predict realistic deflection basins for different materials. Initial findings suggest that Dynatest LWD equipment provides more reliable results compared to Zorn LWD equipment, based on FE simulations. This study underscored the need for standardized calculation protocols and aimed to refine LWD testing procedures, enhancing the durability and reliability of pavement structures across various construction scenarios.

A torque ripple optimization scheme for SRM drive, based on exhaustive search method and 2-phase excitation model of SRM has been presented in this paper. The 2-phase excitation model of SRM used here takes into account the nonlinear effects because of saturation and mutual flux linkages caused by multi-phase excitation. In the proposed scheme the incoming and outgoing phase currents are modulated to minimize the torque ripple. Because of the highly nonlinear nature of torque, exhaustive search method is used for optimizing the torque ripple, by simulating the model multiple times. Modulation of phase current is done by addition, subtraction and multiplication of constants and variables. This can be very easily achieved in DSP micro-controllers and FPGAs. It has been shown by simulations, that the proposed optimization scheme reduces the torque ripple by more than 50% as compared to constant current scheme. The proposed optimization scheme has been experimentally validated

Parameter identification of modified fractional Zener model for thermorheological materials

Modified hybrid bat algorithm with genetic crossover operation and smart inertia weight for multilevel image segmentation

Trading strategies for image segmentation using multilevel thresholding aided with minimum cross entropy

For the future advanced applications in consumer electronic products, the need of flexible interconnects increases rapidly. The reliability study of ultra-thin chip-on-flex (UTCOF) interconnects using anisotropic conductive adhesive (ACA) is thus reported herein. When the flexible device is bent, since the interface between ultra-thin chip (<50 mum in thickness) and substrate may create the major possibility for delamination, the flexibility of ultra-thin silicon chip is first evaluated by 3-point bending test. The ACA-P and ACA-F materials are assembled at different bonding temperatures to study the temperature effects of bonding on the interface adhesion for substrate-adhesive and adhesive-passivation layer by differential scanning calorimeter (DSC) measurement and peeling test. The contact resistance of daisy chain with 188 I/Os is measured to evaluate the bonding quality through the 80 mum pitch dummy test samples. The flexibility of the UTCOF interconnects bonded with ACA joints is then performed by the static and 4-point bending tests. The reliability of UTCOF interconnects with ACA is also evaluated by the 85 degC/85%RH thermal humidity storage test (THST) for 1,000 hours. To demonstrate the techniques developed, the interface between ultra-thin silicon chip and substrate is finally inspected through the cross-section SEM works. As expected, the average maximum allowable deflections of the UTCOF interconnects by using ACA-P and ACA-F materials increase 26% and 153% as compared with those obtained by COF ones with 670 mum chip thickness, respectively. Moreover, the contact resistance remains stable and varies under 10% with the bending curvature 30 mm for 1,000 hours. Based on the results achieved, the UTCOF with ACA joints presented in this work would be reliable for serving as the flexible interconnects by choosing an appropriate ACA material and optimum curing conditions.

The existing cement concrete pavement treated with rubblization technique was regarded as a linear, isotropic elastic body at macro level. By using a double-layer elastic system model, the stress and deflection of asphalt overlay were analyzed, the minimum resilient modulus and maximum allowable deflection on rubblized cement concrete pavement related to different traffic volumes and asphalt overlay thicknesses were analysed. The analytic result indicates that in general the surface deflection on rubblized cement concrete pavement should vary from 41 to 114 (×0.01 mm) against different traffic volumes and asphalt overlay thicknesses, otherwise the rubblized cement concrete pavement is incapable of meeting the requirement on structural stiffness, and a base layer shall be placed before paving asphalt overlay.

This paper introduces two simplified equations, "Nori formulae," for calculating maximum allowable stress (MAS) in mechanical design engineering. These formulae eliminate the need for traditional safety margins or factors of safety along with factored values across applications ranging from safety pins to spacecraft components. The first formula determines the maximum allowable stress in tension, while the second addresses the maximum allowable stress in shear. The Nori formulae were developed by incorporating fundamental mechanical properties of steel: ultimate tensile strength, yield strength, elongation, and reduction of area—all commonly derived from engineering stress-strain curves in standard tensile testing. This approach effectively utilizes existing global databases of elongation and reduction of area measurements, requiring no additional data generation that would otherwise demand significant time and financial investment. This work addresses a critical gap in the field, as various international design codes and standards currently employ inconsistent design philosophies and safety margins when determining the maximum allowable stress for steel materials.