Use Of Superstructures Research Articles

Quality Control of the Thermal Properties of Superstructures in Accommodation Spaces in Naval Constructions

The application of passive design strategies in ships, such as the use of superstructures with high thermal insulation, allows the energy demand of heating, ventilation, and air conditioning systems to be reduced. There is a knowledge gap in the scientific literature on the possibilities to thermally characterize superstructures. Knowing such possibilities would make a methodology available for the quality control of naval constructions and for the inspection of the appropriate state of insulations in existing ships. For this purpose, a total of three different typologies of ship superstructures were monitored, and the data obtained were analyzed by using various existing approaches for the thermal characterization of façades: the heat flow meter method and temperature measurement methods. The results showed that the heat flow meter method constitutes a valid methodology to obtain representative results. In addition, guaranteeing a thermal gradient dependent of the wall typology and placing probes in zones not influenced by thermal bridges ensure that representative results are achieved.

A new stage-wise superstructure for heat exchanger network synthesis considering substages, sub-splits and cross flows

Several optimization models for process synthesis and optimization are derived from superstructures. Those used for Heat Exchanger Networks (HEN) must comprise consistent design options so that efficient structures may be found. The complexity arisen from nonlinearities and non-convexities in the mathematical models for HEN synthesis, though, hampers the use of superstructures with elaborated streams splits and mixing alternatives as well as multiple options for devices allocation. In this work, a new superstructure based on a previous stage-wise one is presented encompassing, for each process stream, the use of splits, sub-splits, cross flows (i.e., partial stream mixing), serial heat exchanger allocation in single stream split branches and heaters/coolers allocation in intermediate stages of the structure (i.e., before process streams heat exchangers). The meta-heuristic approach used to solve the optimization model was able to achieve solutions better than those previously reported in the literature for five case studies, demonstrating efficiency in solving such complex model.

An Enhanced Stage-wise Superstructure for Heat Exchanger Networks Synthesis with New Options for Heaters and Coolers Placement

Several methods for heat exchanger networks (HEN) design are based on the use of superstructures. The models they give rise to can lead to different design options to be explored in HEN synthesis. In this work, a stage-wise superstructure with new features for the optimal placement of heaters and coolers, including the possibility of the use of multiple utilities, is presented. In the model, those units can be placed in different stream split branches in all stages, differing from the usual allocation at stream ends. Such possibilities yield a more complex mathematical model. To solve it, an improved version of a previously presented hybrid meta-heuristic method was used. Three examples from the literature were studied. The use of the superstructure with the additional utility-related options, as well as the enhanced meta-heuristic solution method, led to configurations with lower associated total annual costs than those reported in previous works.

Superstructure-free synthesis and optimization of thermal power plants

The optimal synthesis and design of thermal power plants is best addressed using mathematical optimization techniques. However, conventional optimization methods require the user to manually define a priori the potential solution space through the modeling of a superstructure, which is a time-consuming, complex, and error-prone task. More importantly, the final superstructure model can not guarantee to contain all good alternatives (in particular, the optimal solution), while it might consider a huge number of meaningless or even infeasible alternatives. To circumvent the use of superstructures, recently, a generic superstructure-free optimization approach has been proposed by the authors to synthesize distributed energy supply systems. The approach employs hybrid optimization integrating evolutionary and deterministic optimization to enable simultaneous alternatives generation and optimization. In this paper, the approach is extended by a new mutation rule to enable the synthesis of thermal power plants. The features of the extended superstructure-free approach are illustrated by a case study. The optimization is initialized with the simplest plant cycle consisting of one turbine, one pump, one steam generator, and one condenser. The superstructure-free approach automatically identifies highly efficient and complex structures featuring multi-stage reheating and feedwater preheating.

Efficient methods for learning Bayesian network super-structures

Learning large Bayesian networks (BN) from data is a challenging problem due to the vastness of the structure space. An effective way to turn this problem affordable is the use of super-structures—SS (undirected graphs that contain the BN skeleton). However, the literature has been lacking of specialized methods for estimating SS. We present here two algorithms intended for such purpose in the hybrid approach of BN structure learning. The first one, called Opt01SS, learns SS using only zero-and-first-order conditional independence (CI) tests in a way that allows dealing with the presence of approximate-deterministic relationships and inconsistent CIs, commonly found in small samples. The second algorithm, called OptHPC, is a computational optimized version of the recent HPC algorithm (De Morais and Aussem 2010, [17]) that showed an attractive accuracy for SS recovery. Results on various benchmark networks showed that the proposed algorithms achieve a balance between sensitivity and specificity clearly more favorable for the task of SS estimation than several representative state-of-the-art methods. The computational cost was also found to be reasonable, being Opt01SS one of the most competitive among the analyzed algorithms.

The Milwaukee Brace

The second edition of this useful small book, first published in 1973, has been modified to bring it in line with current practices in brace management of spinal deformities. Recognition of the possible harmful effects of excess radiation is acknowledged by recommendations that substantially reduce the number of recommended radiographs. The use of underarm braces with no neck ring or metallic superstructure for curves in the low thoracic and lumbar regions is described. Also, the indications for the use of superstructure are clarified, namely, in curves with their apices above the tenth thoracic vertebra and in the management of Scheuermann's kyphosis. Long-term studies performed by the authors have shown the tendency for a curve to return toward its original degree long after the brace has been removed. Because of this knowledge, the indications for brace management have been redefined. A brace and exercise program is indicated for curves between 20°