Shape optimization of multi-chamber cross-flow mufflers by SA optimization

Because of the necessity of maintenance and operation in industries in which the equipment layout is occasionally tight, the space for a muffler is constrained. An interest in maximizing the acoustical performance of mufflers within a limited space is of paramount importance. As mufflers hybridized with reverse-flow ducts may visibly increase acoustical performance, the main purpose of this paper is to numerically analyze and maximize their acoustical performance within a limited space. In this paper, a four-pole system matrix for evaluating the acoustic performance —sound transmission loss (STL)— is derived by using a decoupled numerical method. Moreover, simulated annealing (SA), a robust scheme used to search for the global optimum by imitating the metal annealing process, has been used during the optimization process. Before dealing with a broadband noise, the STL’s maximization with respect to a one-tone noise (300 Hz) is introduced for a reliability check on the SA method. Moreover, an accuracy check of the mathematical model is performed. Results reveal that the STL of a muffler with reverse-flow perforated ducts can be maximized at the desired frequency for pure tone elimination; moreover, the noise reduction for a broadband noise can reach 97.5 dB. Consequently, the approach used for the optimal design of the mufflers is simple and effective.

It has been noted that the application of high performance, compact mufflers is the future for modern factories where place is at a premium. However, as research on mufflers equipped with extended tubes has been exhausted, and frankly at the juncture, shown to be inadequate (unsuitable), attention has turned to mufflers conjugated with perforated intruding tubes which can dramatically increase acoustical performance. Therefore, the focus of this paper is not only to analyze the sound transmission loss (STL) of a one-chamber open-ended perforated muffler but also to optimize the best design shape within a limited space. In this paper, the four-pole system matrix for evaluating the acoustic performance ― sound transmission loss (STL) ― is derived by using a decoupled numerical method. Additionally, a simulated annealing (SA), a robust scheme used to search for the global optimum by imitating the metal's heating process, has been used during the optimization process. Before dealing with a broadband noise, the STL's maximization with respect to a one-tone noise is introduced for a reliability check on the SA method. Also, an accuracy check on the mathematical model is performed. To appreciate the acoustical ability of the new mufflers, traditional mufflers, including a simple expansion muffler as well as a non-perforated intruding-tube muffler, have been assessed. Results reveal that the maximal STL is precisely located at the desired targeted tone. In addition, the acoustical performance of mufflers conjugated with perforated intruding tubes is found to be superior to the traditional mufflers. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is quite effective.

Optimization of process parameters in the abrasive waterjet machining using integrated SA–GA

This paper explores the potential of quantum computing on a WCET(Worst-Case Execution Time (of a program).)-related combinatorial optimization problem applied to a set of several polynomial special cases. We consider the maximization problem of determining the most expensive path in a control flow graph. In these graphs, vertices represent blocks of code whose execution times are fixed and known in advance. We port the considered optimization problem to the quantum framework by expressing it as a QUBO. We then experimentally compare the performances in solving the problem of classic Simulated Annealing (SA), Quantum Annealing (QA), and Quantum Approximate Optimization Algorithm (QAOA). Our experiments suggest that QA represents a fast equivalent of simulated annealing. Indeed, we measured the approximation ratio on the results of QA and SA, showing that their performances are comparable, at least on our set of simplified problems.KeywordsWCETsQuantum computingQUBOCombinatorial optimizationQuantum annealingQAOA

Recently, research on new techniques of single-chamber mufflers equipped with a non-perforated intruding tube has been addressed; however, the research work on multi-chamber mufflers conjugated with open-ended perforated intruding inlet-tubes which may dramatically increase the acoustical performance has been neglected. Therefore, the main purpose of this paper is not only to analyze the sound transmission loss (STL) of a multi-chamber open-ended perforated inlet-tube muffler but also to optimize the best design shape within a limited space. In this paper, the four-pole system matrix for evaluating the acoustic performance - sound transmission loss (STL) - is derived by using a decoupled numerical method. Moreover, a genetic algorithm (GA), a robust scheme used to search for the global optimum by imitating a genetic evolutionary process, has been used during the optimization process. Results reveal that the maximal STL is precisely located at the desired tone. In addition, it has been shown that the acoustic performance for both pure tone and broadband noise will increase if the muffler has more chambers.

Research on new techniques of multi-chamber mufflers equipped with a side inlet and an internal non-perforated tube has been well addressed and developed; however, the research work of multi-chamber mufflers in conjunction with side inlet and internal perforated tubes which may efficiently increase the acoustical performance is rare. Therefore, the main purpose of this paper is to not only analyze the sound transmission loss (STL) of three-chamber side mufflers with a perforated tube but also to optimize their best design shape under a limited space. In this paper, both the generalized decoupling technique and plane wave theory in solving the coupled acoustical problem are used. The four-pole system matrix in evaluating the acoustic performance is also deduced in conjunction with a simulated algorithm (SA). To verify the liability of the SA technique, the noise minimization of muffles at a targeted frequency is exemplified first. To appreciate the acoustical performance of various multi-chamber mufflers with/without inner perforated tube, three kinds of multi-chamber mufflers ― a one-chamber side muffler, a two-chamber side muffler hybridized with a non-perforated tube, and a three-chamber side muffler hybridized with a perforated tube are introduced and assessed. In eliminating the broadband exhausted noise emitted from an air compressor’s inlet. Before the SA operation can be carried out, the accuracies of the mathematical models have to be checked by experimental data. The result reveals a three-chamber side muffler hybridized with a perforated tube exhibits an excellent acoustical ability beyond the other mufflers. Consequently, the approach used seeking the optimal design of the STL proposed in this study is indeed easy, economical and quite effective.

An optimal shape of two-dimensional asymmetric diffuser with maximum pressure recovery at the exit is numerically obtained using a mathematical theory based on the variational calculus and gradient algorithm. The initial diffuser is taken to be a two-dimensional asymmetric diffuser for which much experimental and numerical data are available. The Reynolds number based on the bulk mean velocity and the channel height at the diffuser entrance is 1.8 × × 10 4 .F rom this initial shape, optimal diffuser shapes are designed for six different geometric constraints, such as the streamwise length and height of the diffuser. The optimality condition for maximum pressure recovery is obtained to be zero skin friction along the diffuser wall. The turbulent flow inside the diffuser is predicted using the k‐� ‐v2‐f model, and optimal shapes are obtained through iterative procedures to satisfy the optimality condition. With the shape design, flow separation that appeared in the initial diffuser is completely removed or significantly reduced. For one of the optimal diffuser shapes obtained, large-eddy simulation is carried out to validate the result of the shape design. The wall shear stress, wall pressure, mean velocity, and turbulence quantities obtained from large-eddy simulation are in good agreement with those from the simulation using the turbulence model.

Noise control is essential in an enclosed machine room where the noise level has to comply with the occupational safety and health act. In order to overcome a pure tone noise with a high peak value that is harmful to human hearing, a traditional reactive muffler has been used. However, the traditional method for designing a reactive muffler has proven to be time-consuming and insufficient. In order to efficiently reduce the peak noise level, interest in shape optimization of a Helmholtz muffler is coming to the forefront. Helmholtz mufflers that deal with a pure tone have been adequately researched. However, the shape optimization of multi-chamber Helmholtz mufflers that deal with a broadband noise hybridized with multiple tones within a constrained space has been mostly ignored. Therefore, this study analyzes the sound transmission loss (STL) and the best optimized design for a hybrid Helmholtz muffler under a space- constrained situation. On the basis of the plane wave theory, the four-pole system matrix used to evaluate the acoustic performance of a multi-tone hybrid Helmholtz muffler is presented. Two numerical cases for eliminating one/two tone noises emitted from a machine room using six kinds of mufflers (muffler A~F) is also introduced. To find the best acoustical performance of a space-constrained muffler, a numerical assessment using a simulated annealing (SA) method is adopted. Before the SA operation can be carried out, the accuracy of the mathematical model has been checked using the experimental data. Eliminating a broadband noise hybridized with a pure tone (130 Hz) in Case I reveals that muffler C composed of a one- chamber Helmholtz Resonator and a one-chamber dissipative element has a noise reduction of 54.9 (dB). Moreover, as indicated in Case II, muffler F, a two-chamber Helmholtz Resonator and a one-chamber dissipative element, has a noise reduction of 69.7 (dB). Obviously, the peak values of the pure tones in Case I and Case II are efficiently reduced after the muffler is added. Consequently, a successful approach in eliminating a broadband noise hybridized with multiple tones using optimally shaped hybrid Helmholtz mufflers and a simulated annealing method within a constrained space is demonstrated.

Simulated annealing was first introduced in 1983 as a generic stochastic algorithmic approach to solve optimization Prof. C. L. Liu and his students H. W. Leong and D. F. Wong were among the earliest EDA researchers who applied simulated annealing to EDA. They solved a wide range of EDA problems with successes and reported their results in a series of papers at premier EDA conferences such DAC and ICCAD. Liu, Leong, and Wong later summarized their works in a research monograph entitled Simulated Annealing for VLSI Design, published in 1988 by Kluwer Academic Publishers. In the Preface of their book, the authors wrote We hope that our experiences with the we employed, some of which indeed bear certain for different problems, could be useful as hints and guides for other researchers in applying the method to the solutions of other problems. Indeed, there were similarities in techniques among Liu's works that had influenced the design of simulated annealing EDA algorithms in the past 20 some years. To better understand Liu's contributions in simulated annealing, one should note that a typical simulated annealing algorithm uses a solution space and a cost function that come directly with the problem. Although computation time may be high, the algorithm is straightforward to design, making simulated annealing an attractive option for difficult problems where clever algorithms are hard to come by. On the contrary, Liu's simulated annealing algorithms have a completely different style: They resemble clever algorithms that attempt to solve difficult problems in polynomial time, and they often have a strong algorithmic flavor with a significant effort spent on optimizing the solution space and cost function. In this talk, we will discuss Prof. Liu's pioneering contributions in simulated annealing for EDA.

The sound transmission losses (STL) of a metal panel with rib reinforcement (MPRR) are studied by both an experimental method and a simulation approach. The experimental method and data processing technique for obtaining STL are presented. Six MPRRs with different number of rib reinforcement and different geometry size of rib reinforcement, and six MPRRs with different type of the pasted damping material are designed and anufactured, and their STL performances are investigated by experimental method. The calculation model for STL of a MPRR is proposed and the calculated STL are compared favorably with the experimental data, which validates the proposed model. The analytical methods and conclusions are instructive for the design and the tuning of STL of MPRRs.

Sound transmission loss of plate-type metastructures: Semi-analytical modeling, elaborate analysis, and experimental validation

A combined strategy of an improved simulated annealing (SA) algorithm and genetic algorithm is presented, with the goal of reducing the computational expenses. The improvements made on the SA algorithm include two parts, i.e., the adaptive regulating for the step vector, and the dynamic testing for the equilibrium of the Metropolis process. The proposed strategy has both the advantage of SA algorithm, the ability to avoid being trapped in a local optimum, and that of genetic algorithm, the ability to use the information about the searched states for the next iteration. A practical application on geometry optimization of pole shoes in large salient pole synchronous generators is effectively implemented using the strategy. The numerical results show that the number of iterations used by executing the combined strategy are only about 75% of those by executing basic SA algorithm.

Network lifetime play a vital role in setting up an energy efficient wireless sensor network. The lifetime of the network can be improved by efficient deployment and scheduling of the sensor nodes inside the network. In this paper, on the basis of mathematically calculated upper bound lifetime of the network, the sensor nodes are efficiently deployed by using Simulated Annealing and Particle Swarm Optimization with pre-specified sensing range of the sensor nodes and on the second fold the sensor nodes are efficiently scheduled by applying the Simulated Annealing and Dempster Shafer Theory. The overall objective of this paper is to find the optimized location and schedule for sensor nodes. The comparative study shows that the simulated annealing and particle swarm optimization algorithms performs better for sensors deployment. Simulated annealing and Dempster Shafer theory achieves the goal to provide the different schedules with high efficiency.

Over recent years, new methods have been developed to integrate uncertainty into the optimisation of life-of-mine production planning. One of these methods is based on scheduling with a simulated annealing (SA) algorithm and equally probable realisations of a given mineral deposit. The latter realisations are used to generate production schedules that minimise the possibility of deviating from production targets, and result in schedules with a substantial improvement in the net present value (NPV), shown to be in the order of 25% when compared to conventional scheduling within the conventionally optimal pit limits. To facilitate the utilisation of this method, a sensitivity analysis is presented in this study. The study documents the case of a copper deposit where 10 simulated realisations are sufficient to provide stable life-of-mine optimisation results. In addition, the study shows that the selected true optimal pit limits are larger than those derived through conventional optimisation. Stochastically optimised pit limits are found to be ∼17% larger, in terms of total tonnage, than the conventional (deterministic) optimal pit limits. The difference adds one year of mining and ∼10% of additional NPV when compared to the NPV of conventional optimal pit limits and a production schedule generated stochastically with the same simulated annealing algorithm.

Summary The Simulated Annealing (SA) algorithm has been widely used in geophysical data processing. However, the seri al SA algorithm is limited by low computing efficiency. In this paper, the annealing schedule has been improved in the SA algorithm, and a constrained inversion of magnetotelluric (MT) data using the parallel SA algorithm has been applied. The test of synthetic data shows that the improved Very Fast Simulated Annealing (VFSA) method is significantly better than the traditional method. Additionally, the computing efficiency has been improved using the parallel SA inversion algorithm. This method has also been applied in MT data processing for geothermal exploration and good geological results have been achieved.