Multi-objective topology optimization of multi-component continuum structures via a Kriging-interpolated level set approach

This paper explores a framework for topology optimization of multi-component sheet metal structures, such as those often used in the automotive industry. The primary reason for having multiple components in a structure is to reduce the manufacturing cost, which can become prohibitively expensive otherwise. Having a multi-component structure necessitates re-joining, which often comes at sacrifices in the assembly cost, weight and structural performance. The problem of designing a multi-component structure is thus posed in a multi-objective framework. Approaches to solve the problem may be classified into single and two stage approaches. Two-stage approaches start by focusing solely on structural performance in order to obtain optimal monolithic (single piece) designs, and then the decomposition into multiple components is considered without changing the base topology (identical to the monolithic design). Single-stage approaches simultaneously attempt to optimize both the base topology and its decomposition. Decomposition is an inherently discrete problem, and as such, non-gradient methods are needed for single-stage and second stage of two-stage approaches. This paper adopts an implicit formulation (level-sets) of the design variables, which significantly reduces the number of design variables needed in either single or two stage approaches. The number of design variables in the formulation is independent from the meshing size, which enables application of non-gradient methods to realistic designs. Test results of a short cantilever and an L-shaped bracket studies show reasonable success of both single and two stage approaches, with each approach having different merits.     

Development of a novel 6LoWPAN-based multipurpose sensor monitoring and notification system

In the area of wireless communication technologies, 6LoWPAN leverages the extensive capabilities of IPv6, even within the constraints imposed by resource-limited devices, particularly within wireless sensor networks (WSNs). The integration of 6LoWPAN into modern solutions for implementing the IPv6-based Internet of Things (IoT) is becoming increasingly important. In this paper, a sensor monitoring and notification system specifically designed for deployment over 6LoWPAN has been proposed. Multipurpose capability, scalability, and ease of deployability are the main features of the proposed system. Its architecture reflects the highest degree of flexibility and allows for a variety of use cases encountered in practical scenarios. In addition, a web interface has been developed as part of the comprehensive system architecture. This interface enables efficient management of the entire system and facilitates connection for new users and seamless integration of additional sensors. By encapsulating complex functions in a user-friendly interface, the system promotes accessibility, convenience, and an enhanced user experience. The proposed system overcomes the limitations of current approaches, thereby creating new opportunities. The flexibility of the proposed system allows it to be applied to various use cases.     

A novel approach to prediction of rheological characteristics of jet grout cement mixtures via genetic expression programming

Highly nonlinear flow behavior of cement-based grout mixtures has always become an important issue for experimenters during jet grouting applications. In this viewpoint, an investigation has been addressed in this paper on the applicability of a recent soft computing prediction tool, genetic expression programming (GEP), to the prediction of rheological characteristics (i.e., shear stress, viscosity) of the grout mixtures with various stabilizers (clay, sand, lime) for jet grouting purposes. The experimental data (shear stress versus shear rate with respect to stabilizer dosages) of grout mixtures obtained from rheometer tests have been collected from previous study conducted in a wide range of stabilizer dosage rates (0–100 %, by dry weight of binder). For predicting the shear stress and viscosity as the output variables during the train and testing stages, the input variables in the GEP models included shear rate and stabilizer dosage primarily. As a consequence of GEP modeling compared with measured data, this study reveals satisfactory GEP formulations in a good accuracy (R ≥ 0.86) for predictions of shear stress and viscosity regarding the stabilizer additions. The GEP formulas are also found adequate for modeling the flow behavior of the shear stress–shear rate, alternatively to conventional nonlinear regression and rheological models (Herschel–Bulkley, Robertson–Stiff). For assistance of preliminary evaluations, the derived GEP formulas could be potentially considered in practice for estimations of pumping pressure (shear stress), pumping rate (shear rate) and viscosity of jet grout mixtures.

     

A bigraphical model for specifying cloud-based elastic systems and their behaviour

The few recent years have witnessed the appearance of a new kind of self-adaptive systems called cloud based-elastic systems. These systems are particularly appealing for their ability to maintain a decent quality of service and reduce a system’s operating cost at the same time. They achieve this by dynamically adjusting resources allocation in terms of elasticity. Meanwhile, complexity of structural and behavioural aspects related to cloud-based elastic systems increase the difficulty of designing and developing such systems. In this paper, we address this challenge by proposing a formal approach based on bigraphical reactive systems for modelling both structural and behavioural aspects of cloud-based elastic systems. In particular, we represent their behaviour in terms of client/application interactions and elasticity methods at different levels using bigraphical reaction rules. The feasibility of the proposed approach is illustrated through a motivating example running on the top of an Amazon Elastic Compute Cloud (EC2) infrastructure.     

A qualitative exploration of arts-based neighbourhood revitalization: The case of ‘The Space at 2106 Main’ in West Tampa,Florida

As cities are compelled to compete for new sources of investment and revenue, arts-based economic development strategies have become the norm. The purpose of this paper is to revisit and reevaluate some of the conventional claims about the arts as an important economic development strategy by exploring a case study called “The Space at 2106 Main” in a rapidly gentrifying neighbourhood called West Tampa. The results of this study suggest that the arts are indeed assuming a greater role in economic policy under the auspices of West Tampa community redevelopment areas (CRA) and the direct actions of various arts related entrepreneurs. The results however, point to a mixed picture that raises difficult questions about the medium to long-term effects of this urban redevelopment strategy, especially on the poor and mostly minority residents of West Tampa.