Search results

A system for solving a wide variety of inverse and optimization problems in solid mechanics is introduced. The system consists of a general purpose finite element method (FEM) analysis system “Elfen” and a shell which controls this system. The shell functions as a stand‐alone programme, so the system is physically divided into two separated parts. The “optimization part”, which corresponds to the shell, possesses optimization and inverse problem solution algorithms. The “analysis part”, which corresponds to an FEM system, serves for the definition of the objective function to which these algorithms are applied. The shell has a user interface implemented in the form of file interpreter which imposes a great flexibility at the definition of various optimization and inverse problems, including parameter identification in constitutive modelling, frictional contact problems and heat transfer. Concepts of the shell are discussed in detail.

This paper aims to provide organizations with a new tool to make decisions related to a facility (building) selection process. Traditionally, value engineering (VE) applies the Value = Function/Cost formula to evaluate the worth of a product. In this paper, the VE-based facility-selection approach is proposed, where the cost of a facility is expressed in net present value (NPV) as it contains the net expense of purchasing or leasing a building as well as the time value of money. Also, a method of quantifying functions and involved risks of different facility choices is proposed.

The framework of the VE-based facility-selection process is broken down into three steps: preparation, calculation/analysis and assessment. In the latter part of this paper, the authors share a sample analysis by illustrating the analysis and decision-making process when three hypothetical facility-selection options are available.

The sample analysis indicates that companies can get the lowest cost and risk while improving their functions to achieve the highest value by using the modified VE formula to drive an optimal option for company’s business expansion and facility-selection process.

This paper provides organizations with a strategic system and process to select proper facilities or buildings for business expansion. The VE approach suggested in this study can allow facility/real estate portfolio decision-makers to analyze financial and functional aspects of the facility at the same time and obtain the value coefficient when they choose a new facility from different options. Finally, they can select the best option, which has the highest value coefficient, given financial and functional considerations.

The purpose of this paper is to develop a new mathematical method for the reliability analysis and evaluation of multi-state system (MSS) reliability that agrees with specifics of such system. It is possible based on the application of multiple-valued logic (MVL) that is a natural extension of Boolean algebra used in reliability analysis.

Similar to Boolean algebra, MVL is used for the constriction of the structure function of the investigated system. The interpretation of the structure function of the MSS in terms of MVL allows using mathematical methods and approaches of this logic for the analysis of the structure function.

The logical differential calculus is one of mathematical approaches in MVL. The authors develop new method for MSS reliability analysis based on logical differential calculus, in particular direct partial logical derivatives, for the investigation of critical system states (CSSs). The proposed method allows providing the qualitative and quantitative analyses of MSS: the CSS can be defined for all possible changes of any system component or group of components, and probabilities of this state can also be calculated.

The proposed method permits representing the MSS in the form of a structure function that is interpreted as MVL function and provides the system analyses without special transformation into Boolean interpretation and with acceptable computational complexity.

Three-dimensional computer-aided design (CAD) assembly model has become important resource for design reuse in enterprises, which implicates plenty of design intent, assembly intent, design experience knowledge and functional structures. To acquire quickly CAD assembly models associated with specific functions by using product function requirement information in the product conceptual design phase for model reuse, this paper aims to find an approach for structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model before functional semantic-based assembly retrieval.

An approach for structure-function correlations analysis and functional semantic annotation of CAD assembly model is proposed. First, the product knowledge model is constructed based on ontology including design knowledge and function knowledge. Then, CAD assembly model is represented by part attributed adjacency graph and partitioned into multiple functional regions. Assembly region and flow-activity region are defined for structure-function correlations analysis of CAD assembly model. Meanwhile, the extraction process of assembly region and flow-activity region is given in detail. Furthermore, structure-function correlations analysis and functional semantic annotation are achieved by considering comprehensively assembly structure and assembled part shape structure in CAD assembly model. After that, a structure-function relation model is established based on polychromatic sets for expressing explicitly and formally relationships between functional structures, assembled parts and functional semantics.

The correlation between structure and function is analyzed effectively, and functional semantics corresponding to structures in CAD assembly model are labeled. Additionally, the relationships between functional structures, assembled parts and functional semantics can be described explicitly and formally.

The approach can be used to help designers accomplish functional semantic annotation of CAD assembly models in model repository, which provides support for functional semantic-based CAD assembly retrieval in the product conceptual design phase. These assembly models can be reused for product structure design and assembly process design.

The paper proposes a novel approach for structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model. Functional structures in assembly model are extracted and analyzed from the point of view of assembly structure and function part structure. Furthermore, the correlation relation between structures, assembled parts and functional semantics is expressed explicitly and formally based on polychromatic sets.

To provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.

In this paper, recent researches on efficient reliability analysis and applications in complex engineering structures like aeroengine rotor systems are reviewd.

The recent reliability analysis advances of engineering application in aeroengine rotor system are highlighted, it is worth pointing out that the surrogate model methods hold great efficiency and accuracy advantages in the complex reliability analysis of aeroengine rotor system, since its strong computing power can effectively reduce the analysis time consumption and accelerate the development procedures of aeroengine. Moreover, considering the multi-objective, multi-disciplinary, high-dimensionality and time-varying problems are the common problems in various complex engineering fields, the surrogate model methods and its developed methods also have broad application prospects in the future.

For the strong demand for efficient reliability design technique, this review paper may help to highlights the benefits of reliability analysis methods not only in academia but also in practical engineering application like aeroengine rotor system.

Studies of police organizations typically involve examining predictors consistent with structural contingency theory while comparatively fewer have examined the applicability of institutional theory. The purpose of the current study is to examine the influence of institutional factors on the elaboration of organizational structure, specifically the incorporation of a crime analysis unit into a police organization's structure.

Data were obtained using a 2002 mail survey of law enforcement agencies focusing on the crime analysis function and environmental factors influencing the organization of that function. Additional information complementing the survey data was obtained through telephone interviews with representatives from 12 of the surveyed departments.

Multivariate results show that, consistent with contingency theory, size is an important predictor of structural elaboration. Analyses and interview responses suggest that institutional factors, particularly accreditation standards, may play some role in shaping organizational structures.

The survey was returned by 160 agencies for a response rate of 56 percent but analyses were based on relatively small samples of 67‐77 agencies. Telephone interviews were conducted using a purposive, non‐probability sampling method.

The results of this exploratory study provide insight into factors contributing to the adoption of structures and strategies in policing.

The research is one of only a small number of studies in policing to explicitly test propositions derived from institutional theory, particularly the concept of institutional isomorphism.

This paper aims to analyze the evolution and interaction over time of the functions of a technological innovation system (TIS) based on the concept of an innovation motor.

It is a case study of the innovation system associated with the technology for producing cage-free pullets for laying eggs in Pelotas/Rio Grande do Sul (RS).

The motors proposed by the TIS approach evolve sequentially and are associated with cumulative causality mechanisms. The study's results identified two functionalities: analysis of the chain as a whole and coordination of the actors involved in the system. The study's results also identified the presence of inflection points at the beginning of each of the motors.

The absence of a more accurate detailing of the market motor in discussions of the evolution of the motors and functions of TIS cage free Pelotas.

Innovation Motors as a new guiding approach for participatory innovation initiatives in rural areas.

Application of the TIS approach in agribusiness and proposition of two new functions for motor analysis, in addition to including inflection points as activation triggers in the evolution between motors.

Like all other natural fibers, the physical properties of cotton also vary owing to changes in the related genetic and environmental factors, which ultimately affect both the mechanics involved in yarn spinning and the quality of the yarn produced. However, information is lacking about the degree of influence that those properties impart on the spinnability of cotton fiber and the strength of the final yarn. This paper aims to discuss this issue.

This paper proposes the application of discriminant analysis as a multivariate regression tool to develop the causal relationships between six cotton fiber properties, i.e. fiber strength (FS), fiber fineness (FF), upper half mean length (UHML), uniformity index (UI), reflectance degree and yellowness and spinning consistency index (SCI) and yarn strength (YS) along with the determination of the respective contributive roles of those fiber properties on the considered dependent variables.

Based on the developed discriminant function, it can be revealed that FS, UI, FF and reflectance degree are responsible for higher YS. On the other hand, with increasing values of UHML and fiber yellowness, YS would tend to decrease. Similarly, SCI would increase with higher values of FS, UHML, UI and reflectance degree, and its value would decrease with increasing FF and yellowness.

The discriminant functions can effectively envisage the contributive role of each of the considered cotton fiber properties on SCI and YS. The discriminant analysis can also be adopted as an efficient tool for investigating the effects of various physical properties of other natural fibers on the corresponding yarn characteristics.

The purpose of this paper is to develop a computational technique to couple finite element and meshfree methods for locking‐free analysis of shear deformable beams and plates, and to impose the boundary conditions directly when the matching field approach is adopted in the meshfree region.

Matching field approach eliminates shear‐locking which may occur due to inconsistencies in the approximations of the transverse displacement and rotation fields in shear‐deformable beams and plates. Continuous blending method is modified in order to be able to satisfy the constraint conditions of the matching field strategy.

For both transverse displacement and rotation fields, the developed technique produces approximation functions that satisfy the Kronecker delta property at the required nodes of the meshfree region when the matching field approach is adopted.

This approach allows for direct assembly of the stiffness matrices that are built for separate finite element and meshfree regions when the matching field approach is adopted. The boundary conditions can be directly applied, and the reaction forces can also be calculated directly from the structural stiffness matrix by using the developed technique.

Aiming at the inefficiency of solving the Sobol index using the traditional mathematical analytical method, a Sobol global sensitivity analysis method is proposed.

In this paper, a support vector regression (SVR) surrogate model is constructed to solve the Sobol index. The optimal combination of SVR hyperparameters is obtained by using the improved beluga whale optimization (IBWO). Meanwhile, in order to solve the problem that Sobol sequences will form correlation regions in high-dimensional space leading to the uneven distribution of sampling points, a scrambled strategy is introduced in the Sobol sensitivity analysis using IBWO-SVR. Thus, the IBWO-SVR-SS sensitivity analysis model is established.

The results of two test functions show that the method further improves the accuracy of the sensitivity analysis. Finally, the first-order Sobol index and second-order Sobol index are solved by the IBWO-SVR-SS method using the metro bogie frame as an engineering example. Through the analysis results, the key design parameters of the frame and the design parameter combinations with more obvious coupling relationships are identified, providing a strong reference for the subsequent analysis and structural optimization.

Sobol sensitivity analysis using the surrogate model method can effectively improve the efficiency of the solution. In addition, IBWO is used for the optimization of the SVR hyperparameters to improve the accuracy and efficiency of the optimization, and finally, the correction of the Sobol sequence through the introduction of the disruption strategy also further improves the accuracy of the sensitivity analysis of Sobol.