Engineering Computer Research Articles

An explicit time integration scheme of numerical manifold method

The traditional numerical manifold method (NMM) has the advantage of simulating a continuum and a discontinuum in a unified framework based on a dual cover system. However, since an implicit time integration algorithm is used, the computational efficiency of the original NMM is very low, especially when more contacts are involved. The present study proposes an explicit version of the NMM. Since a lumped mass matrix is used for the manifold element, the accelerations by the corresponding physical covers can be solved explicitly without forming a global stiffness matrix. The open–close iteration is still applied to ensure computational accuracy. The developed method is first validated by two examples, and a highly fractured rock slope is subsequently simulated. Results show that the computational efficiency of the proposed explicit NMM has been significantly improved without losing the accuracy. The explicit NMM is more suitable for large-scale rock mass stability analysis and it deserves to be further developed for engineering computations in rock engineering.

The (R, S)-symmetric least squares solutions of the general coupled matrix equations

Let and be two real symmetric orthogonal matrices. An real matrix is said to be an -symmetric matrix if . The -symmetric matrices have been widely used in engineering and scientific computing. In this paper, we construct an algorithm to solve the general coupled matrix equations , where is a -symmetric matrix. The algorithm produces suitable such that is minimized within a finite number of iteration steps in the absence of round-off errors. We show that the algorithm is stable any case. The algorithm requires little storage capacity. Numerical examples are given to show that the algorithm is efficient.

Parallel computation of Entropic Lattice Boltzmann method on hybrid CPU–GPU accelerated system

Nowadays, an increasing number of researchers have demonstrated a tendency to choose hybrid CPU–GPU hybrid computing as a high performance computing alternative. Entropic Lattice Boltzmann method (ELBM) parallelization, like many parallel algorithms in the field of rapid scientific and engineering computing, has given rise to much attention for applications of computational fluid dynamics. This study aims to present an efficient implementation of ELBM flow simulation for the D3Q19 model in a hybrid CPU–GPU computing environment, which consists of AMD multi-core CPUs with NVIDIA Graphics Processing Units (GPUs). To overcome the GPU memory size limitation and communication overhead, we propose a set of techniques for the development of an efficient ELBM algorithm for hybrid CPU–GPU computation. Considering the contribution of computational capacity for both the CPU and GPU, an efficient load balancing model is built. The efficiency and accuracy of the proposed approach and established model are tested on a hybrid CPU–GPU accelerated system, where the intensive parts of the computation are dealt with the software framework OpenMP and CUDA. Finally, we show the comparison of resulting computational performance using a hybrid CPU–GPU approach against both a single CPU core and a single GPU device.

A New Method To Predict the Performance of Gas-Condensate Reservoirs

Summary Gas-condensate reservoirs differ from dry-gas reservoirs. The understanding of phase and fluid flow-behavior relationships is essential if we want to make accurate engineering computations for gas-condensate systems. Condensate dropout occurs in the reservoir as the pressure falls below the dewpoint, resulting in significant gas-phase production decreases. The goal of this study is to understand the multiphase-flow behavior in gas-condensate reservoirs and, in particular, to focus on estimating gas-condensate-well deliverability. Our new method analytically generates the inflow-performance-relationship (IPR) curves of gas-condensate wells by incorporating the effect of condensate banking as the pressure near the wellbore drops below the dewpoint. The only information needed to generate the IPR is the rock relative permeability data and a constant-composition-expansion (CCE) experiment. We have developed a concept of critical oil saturation near the wellbore by simulating both lean and rich condensate reservoirs and have observed that the loss in productivity caused by condensate accumulation can be closely tied to critical saturation. We are able to reasonably estimate re-evaporation of liquid accumulation by knowing the CCE data. We validated our new method by comparing our analytical results with fine-scale-radial-simulation-model results. We demonstrated that our analytical tool can predict the IPR curve as a function of reservoir pressure. We also developed a method for generating an IPR curve with field data and demonstrated its application with field data. The method is easy to use and can be implemented quickly. Another advantage of this method is that it does not require the knowledge of accurate production data including the varying condensate/gas ratio (CGR).

Optically Allowed Photoluminescence from a Direct-Gap Si-Ge Superstructure on Si0.4Ge0.6

Light emission from Si nanostructures has been of great interest for some time now owing to the need for silicon-based light sources for applications in silicon photonics. Both Si and Ge possess indirect band gaps, which makes them very inefficient light emitters. Band gap engineering has been proposed as one way to overcome this limitation and although light emission with greatly improved efficiency has been obtained at low temperatures the emission at room temperature is still very weak, because of exciton dissociation. Recently, through employing novel band gap engineering computations, entirely new Si/Ge [M. d’Avezac, J.-W. Luo, T. Chanier, and A. Zunger, Phys. Rev. Lett. 108, 027401 (2012)] and Si [H. J. Xiang, B. Huang, E. Kan, S.-H. Wei, and X. G. Gong, Phys. Rev. Lett. 110, 118702 (2013)] supercell structures possessing direct gaps have been proposed. According to d’Avezac et al., a SiGe2Si2Ge2SiGen superstructure should have a direct and dipole-allowed gap of 0.863 eV, which is ideally suited for optical fiber data transmission applications. Here we report on the growth of such a structure and its optical properties. Two similar samples were prepared by different growth methods: molecular beam epitaxy (MBE) and solid phase epitaxy (SPE). In both samples the superstructure (terminated with n = 12 monolayers of Ge) was grown on a 30-nm thick buffer layer of Si0.4Ge0.6 on a 5 µm thick relaxed buffer layer of Si0.4Ge0.6on a 750 µm thick (001) Si substrate. The photoluminescence (PL) spectra were measured using a Bomem DA3 FTIR spectrometer, with the samples excited at low temperatures with either 70 mW of 405 nm or 35 mW of 458 nm laser light.Photoluminescence (PL) spectra obtained at 6 K with excitation at 405 nm are shown in Fig. 1. Similar spectra were obtained with 458 nm excitation. No PL was detected from the two samples in the energy range 1000-1850 meV or at room temperature. The sharp drop at low energy near 700 meV is due to the cut-off in the instrumental response. A strong low-energy PL doublet is seen, with peaks near 780 and 820 meV, together with a much weaker peak at 872 meV. The ratio of intensities of the strong and weak peaks is the same in both samples. The intensities of all three PL peaks decrease with increasing temperature up to 25 K, but the weak peak decreases in intensity faster than that of the strong peaks. The weak peak at 872 meV is most likely the dipole-allowed direct-gap transition expected at 0.863 eV in the superstructure. The small difference in energy between theory and experiment could be the result of a difference in strain within the layer in the sample compared with the ideal (perfect) modeled structure or from assumptions in parameter values in the model. The strong peaks at 820 and 780 meV are assigned to the no-phonon and transverse-optic-phonon emission lines, respectively, of the Si0.4Ge0.6 buffer layer. The ~40 meV separation between the two strong peaks is characteristic of the phonon energies in SiGe alloys. The energies of the peaks, however, are much lower than that expected for a bulk Si0.4Ge0.6 alloy (~0.97 eV). The energies and general appearance of these peaks is reminiscent of what has been obtained from PL studies of SiGe nanostructures imbedded in Si. It is therefore likely that this PL arises predominately at the Si0.4Ge0.6/superstructure interface where there is type-II band alignment. In conclusion, we have obtained experimental evidence of the predicted direct-gap optically-allowed transition in a special supercell comprised of a number of ultrathin layers of Si and Ge.

User-Centered Requirement Engineering for Accessible Chats in m-Learning

Chat applications are useful synchronous tools in mobile learning (m-learning) environments. However, these tools have accessibility problems which cannot be avoided by students and teachers with disabilities. This paper focuses on detecting these accessibility problems. Specifically, this paper presents the Requirement Engineering (RE) process carried out to obtain the requirements needed to improve the interaction for people who experience problems with the Flow and Rhythm of the conversation in chats. A methodological approach has been followed and Software Engineering (SE) and Human Computer Interaction (HCI) disciplines were combined in order to improve the interaction during the chat.

Design on Test Bench of Safety Belt Emergency Locking Property

The mechanical system and controlling system of test bench of safety belt emergency locking property are designed. Safety belt emergency locking property of a moving cars rider can be simulated by changing direct currents acceleration, so multifarious cars safety belt emergency locking property can be examined by the equipment which is developed by using engineering computer as control center,PARKER1505 and VC6.0.Fuzzy PID control algorithm is adopted to decrease the influence and enhance the systems robust.

ASYMPTOTIC FORMULAE FOR THE ACOUSTIC SELF-IMPEDANCE OF SIMPLY-SUPPORTED AND SIMPLY SUPPORTED-CLAMPED ANNULAR PLATES

This study focuses on the sound radiation of a vibrating flat annular plate. The rigorous theoretical considerations deal with sometime-harmonic and axisymmetric vibrations. Three different boundary configurations are considered, i.e. one of the plate’s edges is simply supported and the other one is clamped or also is simply supported. The active and reactive self-impedance of the system are presented in their Hankel’s representations, valid within the whole frequency spectrum. The expressions obtained are transformed to their elementary forms, valid for the high frequencies. Low fluid loading and low internal friction of the plate are assumed. The obtained results are illustrated with sample plots in the domain of acoustic wavenumber. Elementary formulae presented can be useful for further theoretical analysis of the total sound power radiated by an excited flat plate in an acoustic fluid as well as for efficient engineering computations.

Assessing the Power Generation Solution by Thermal-chemical Conversion of Meat Processing Industry Waste

The paper presents a waste to energy conversion solution using a pyro-air-gasification process applied to biodegradable residues from meat processing industry integrated with small scale thermodynamic cycle for power generation. The solution of air- gasification at atmospheric pressure is based on experimental research and engineering computation developed during the study. The input data, such as: waste chemical composition, low/high heating value and proximate analysis, correspond to real waste products, sampled directly from the industrial processing line. Separate drying as first stage pre-treatment and integrated partial drying inside the reactor was used. The syngas low heating value of about 4.3MJ/Nm3 is insured by its combustible fraction (H2– 12.2%, CO – 19.2%, CH4 – 1.6%). According to syngas composition the thermodynamic cycle was chosen – Otto gas engine. For a given waste feed-in flow considered in our computation of about 110kg/h the power output obtained is about 50 kWel. The global energy efficiency of the unit is about 15%. The results offer answers to energy recovery waste disposal for residues with characteristics that are not suitable for classic incineration or limit the energy efficiency of the process making it non-economical (the average humidity of the raw waste is about 42% in mass). The research focused on waste to energy conversion process energy efficiency, waste neutralization and power generation.

Applications of Soft Computing in Civil Engineering: A Review

field of engineering is a creative one. The problems encountered in this field are generally unstructured and imprecise influenced by intuitions and past experiences of a designer. The conventional methods of computing relying on analytical or empirical relations become time consuming and labor intensive when posed with real life problems. To study, model and analyze such problems, approximate computer based Soft Computing techniques inspired by the reasoning, intuition, consciousness and wisdom possessed by a human beings are employed. In contrast to conventional computing techniques which rely on exact solutions, soft computing aims at exploiting given tolerance of imprecision, the trivial and uncertain nature of the problem to yield an approximate solution to a problem in quick time. Soft Computing being a multi-disciplinary field uses a variety of statistical, probabilistic and optimization tools which complement each other to produce its three main branches viz., Neural Networks, Genetic Algorithms and Fuzzy Logic. The review paper presents the applications of two major Soft Computing techniques viz., Artificial Neural Networks and Genetic Algorithms in the field of Civil Engineering, which to some extent has replaced the time consuming conventional techniques of computing with intelligent and time saving computing tools.

Review of the book by Piotr Krzyżanowski: ,,Scientific and Engineering Computations - Fast, Reliable and Effective''

Scientific computation is at present one of the most efficient approaches available to researchers and developers for applied mathematics, technical, economical and natural sciences. This book provides practical guidance on how to perform numerical computer simulations using advanced computational and visualization software tools, and the book in particular caters for nonspecialists in this area seeking to utilize such approaches in their work. The book leads the reader step by step through different types of realization of computational tasks, with an increasing degree of depth. Initially MATLAB and Octave software packages are covered, followed by numerical libraries (for example BLAS and LAPACK), methods for optimizing the numerical programs in C and finally visualization packages. Catering for different levels of expertise and covering the most important tools, the book allows the reader to select and learn approaches suitable for their situation and computational task. Throughout there is a rich variety of well selected examples, exercises, source codes, pictures, diagrams and tables collating the experimental results. For example, the reader is familiarized with some numerical applications of solving ordinary and partial differential equations (ODEs or PDEs). In section 7.9.2 the equation of the van der Pola, which appears in the analysis of simple electrical circuits, is discussed. The programming script solving the equation in question is given and important pertinent details are given. Difficulties with the stability of the solution for ODE is on the other hand discussed for the specific Lorentz equation in the following section, 7.9.3., and likewise the pertinent programming script solving the Lorentz system is provided. Then in section 7.10 some numerical examples for solving PDEs are discussed. The classical equation of diffusion over a rectangle is here considered. All important issues related to discretization and the corresponding numerical schemes are covered for this particular type of equation. In summary, this book is particularly recommended to the nonspecialists, as it offers an attractive and soft entrance into the delicate matter of complicated scientific computation. The examples presented in the book are chosen carefully, and the exercises are stimulating, and help the reader gather the author’s expertise. This book should make resolution of computational problems both easier and enjoyable.

The Changing Face of Scientific and Engineering Computing

The guest editors discuss some recent advances in exascale computing, as well as remaining issues.

New Parallel Sparse Direct Solvers for Multicore Architectures

At the heart of many computations in science and engineering lies the need to efficiently and accurately solve large sparse linear systems of equations. Direct methods are frequently the method of choice because of their robustness, accuracy and potential for use as black-box solvers. In the last few years, there have been many new developments, and a number of new modern parallel general-purpose sparse solvers have been written for inclusion within the HSL mathematical software library. In this paper, we introduce and briefly review these solvers for symmetric sparse systems. We describe the algorithms used, highlight key features (including bit-compatibility and out-of-core working) and then, using problems arising from a range of practical applications, we illustrate and compare their performances. We demonstrate that modern direct solvers are able to accurately solve systems of order 106 in less than 3 minutes on a 16-core machine.

Estimation of the compression behaviour of reconstituted clays

The void index is a relative quantity measuring the position of the current void ratio of a clay against the void ratios of the clay at two specific vertical effective stresses (i.e., σv′=100kPa and σv′=1000kPa). Based on this concept, a simple systematic tool is proposed for estimating the compression behaviour of reconstituted clays over a wide range of stresses and water contents. Following the practice of geotechnical engineering computation, the compression behaviour of clays is idealised as linear segments in the Iv~lnp′ (or the void index and the mean effective stress) space. Considering the variation in the available data, there are three related but independent models for describing the compression behaviour of reconstituted clays. The accuracy of estimation increases with the level of available data. The proposed estimation is used to simulate the behaviour of a variety of reconstituted clays over a wide range of stresses and water contents. With different levels of available data, the estimation is evaluated on the basis of these simulations. The proposed estimation can take maximum use of available data and provide a simple yet practical tool for calculating the compression behaviour of reconstituted clays and a basic parameter for geotechnical engineering computations, the compression index. An empirical equation for the initial compression index is also suggested and verified.

Surveying the Evolution of Computing in Architecture, Engineering, and Construction Education

This paper includes the results of an online survey that was conducted by the American Society of Civil Engineers (ASCE) task committee on computing education to assess the evolution of computing in architecture, engineering, and construction (AEC) education in 2012. The committee aims to understand and measure the evolution of computing in civil engineering, architecture, and construction management curricula and evaluate the current state of computing within the AEC curricula. The paper contains an investigation of the levels and concentrations of computer-science knowledge versus computer skills in curricula. In addition, the committee seeks to recognize the similarities and differences between architecture, engineering, and construction management programs by comparing the data associated with these disciplines. The paper also includes a discussion of basic aspects of computing education including the prerequisites that are necessary for further learning. The survey results provide useful benchmarks for decision making regarding research, industry collaboration, and curricula. Findings of the study include: (1) the importance and coverage of computer skills and competence of graduates has increased over the past decade; (2) computing skills are judged to be more important than computer-science knowledge in AEC curricula; (3) the links between computer-science concepts and AEC applications of computing are not yet fully recognized; (4) computing education is not sufficient to meet the demands of the AEC industry and the share of computing courses is less than what educators desire; and (5) scientific concepts of computing are important for preparing architects and engineers for unknown future developments in information technology.

Engineering Calculation and Application of Perforation Impact Dynamic Loads in Oil and Gas well

The perforation impact dynamic loads can destroy or disable the tubing strings. The perforated completion process was simplified to explosion of ordinary explosive charge in perforation liquid. The dimensionless expression of perforation impact dynamic loads was derived based on main influence factors and then its engineering calculation formula was set up. A well perforation operation in western Sichuan as an example, the oil tubing strings security was analyzed by the perforation impact dynamic loads from the engineering computation formula. The results show that the tubing strings only occur elastic spiral bucking and do not occur plastic deformation which are in line with perforation operation results on site.

FDS Simulation High Rise Building Model for Unity 3D Game Engine

Smoke simulation is an interesting topic in simulation fluid dynamics and graphics area. Stack Effect Fire model was happened in fire of High Rise building. Simulation this fire model and smoke scene is one of the most challenging tasks in fluid dynamics of computer graphics area. In this paper proposed Smoke simulation rendering is based on game engine of particle system. But common game engine don’t have stack effect model and compute coordinate position algorithm. Recently proposed method based on FDS’s (Fire Dynamic Simulation) result Excel file which improves Unity 3D game engine for stake effective fire model and smoke boundaries. Using Excel file coordinates to improve Unity 3D game engine particle system, and changes the original game engine particle system, over the coordinates of particles moving location, boundary and fire model stake effect look like real world fire model. Recently game engine computer graphic researcher usually control computing resources focused on smoke visualization skip fire effect and physically problem. In this paper, need focused on smoke location boundary and fire model stake effect. The proposed method can change smoke and fire model of stack effect and particles more accurately and efficiently than other, rendering is implemented by making smoke particles and physically effect. After putting the coordinate form FDS into Unity3D game engine Experiment performance result shows particles more look like reality, and gives neutrality and reality to user's view. This algorithm problem is from simulation high rise building mesh with loading time need more computer resource, and need to change some effect in Unity 3D game asset.

The Semantics of Web Services: An Examination in GIScience Applications

Web service is a technological solution for software interoperability that supports the seamless integration of diverse applications. In the vision of web service architecture, web services are described by the Web Service Description Language (WSDL), discovered through Universal Description, Discovery and Integration (UDDI) and communicate by the Simple Object Access Protocol (SOAP). Such a divination has never been fully accomplished yet. Although it was criticized that WSDL only has a syntactic definition of web services, but was not semantic, prior initiatives in semantic web services did not establish a correct methodology to resolve the problem. This paper examines the distinction and relationship between the syntactic and semantic definitions for web services that characterize different purposes in service computation. Further, this paper proposes that the semantics of web service are neutral and independent from the service interface definition, data types and platform. Such a conclusion can be a universal law in software engineering and service computing. Several use cases in the GIScience application are examined in this paper, while the formalization of geospatial services needs to be constructed by the GIScience community towards a comprehensive ontology of the conceptual definitions and relationships for geospatial computation. Advancements in semantic web services research will happen in domain science applications.

Editorial

I am pleased to announce and welcome three new associate editors who recently joined the editorial board of the Journal: Dr. Xiaoping Du, Dr. Harrison Kim, and Dr. Kazuhiro Saitou.Dr. Xiaoping Du is an Associate Professor in the Department of Mechanical and Aerospace Engineering at Missouri University of Science and Technology. He received his B.S., M.S., and Ph.D. degrees from Chongqing University, China, Shanghai Jian Tong University, China, and the University of Illinois at Chicago, respectively, all in Mechanical Engineering. He served as an Associate Professor of Mechanical Engineering at Southwest Petroleum University in China. Dr. Du has also experience as a mechanical engineer at two companies. Dr. Du's areas of research include design under uncertainty, reliability, and optimization.Dr. Harrison Kim is an Associate Professor in the Department of Industrial and Enterprise Systems Engineering at the University of Illinois at Urbana-Champaign. He received his B.S. and M.S. degrees from the Korea Advanced Institute of Science and Technology (KAIST), and his Ph.D. from the University of Michigan, all in Mechanical Engineering. Dr. Kim is an editorial board member for the Engineering Optimization journal. Dr. Kim's areas of research include complex systems design, product design analytics, multidisciplinary design optimization, sustainability and market systems, and energy systems engineering.Dr. Kazuhiro Saitou is a Professor of Mechanical Engineering at the University of Michigan, Ann Arbor. He received a B.E. degree from the University of Tokyo, and M.S. and Ph.D. degrees from the Massachusetts Institute of Technology. He is a past chair of the ASME Design Automation Conference, ASME Design Automation Committee, and ASME Design for Manufacturing and the Life Cycle Committee. He has served as an associate editor for the ASME Journal of Computing and Information Science in Engineering, and IEEE Transactions on Automation Science and Engineering. Dr. Saitou's areas of research include assembly design, structural optimization, manufacturing systems, and biomedical image processing.I would also like to take this opportunity and thank the associate editors who have recently completed their term. These are Janet Allen, Diann Brei, Jim Schmiedeler, and Timothy Simpson.For more information about the Journal, please also refer to its companion site: www.asmejmd.org.

A theoretical global optimization method for vapor-compression refrigeration systems based on entransy theory

The vapor-compression refrigeration systems have been one of the essential energy conversion systems for humankind and exhausting huge amounts of energy nowadays. Surrounding the energy efficiency promotion of the systems, there are lots of effectual optimization methods but mainly relied on engineering experience and computer simulations rather than theoretical analysis due to the complex and vague physical essence. We attempt to propose a theoretical global optimization method based on in-depth physical analysis for the involved physical processes, i.e. heat transfer analysis for condenser and evaporator, through introducing the entransy theory and thermodynamic analysis for compressor and expansion valve. The integration of heat transfer and thermodynamic analyses forms the overall physical optimization model for the systems to describe the relation between all the unknown parameters and known conditions, which makes theoretical global optimization possible. With the aid of the mathematical conditional extremum solutions, an optimization equation group and the optimal configuration of all the unknown parameters are analytically obtained. Eventually, via the optimization of a typical vapor-compression refrigeration system with various working conditions to minimize the total heat transfer area of heat exchangers, the validity and superior of the newly proposed optimization method is proved.