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A transport equation for the one‐point velocity probability density function (pdf) of turbulence is derived, modelled and solved. The new pdf equation is obtained by two modeling steps. In the first step, a dynamic equation for the fluid elements is proposed in terms of the fluctuating part of Navier‐Stokes equation. A transition probability density function (tpdf) is extracted from the modelled dynamic equation. Then the pdf equation of Fokker‐Planck type is obtained from the tpdf. In the second step, the Fokker‐Planck type pdf equation is modified by Lundgren’s formal pdf equation to ensure it can properly describe the turbulence intrinsic mechanism. With the new pdf equation, the turbulent plane Couette flow is solved by the direct finite difference method coupled with dimensionality reduction and QUICKER scheme. A simple boundary treatment is proposed such that the near‐wall solution is tractable and then no refined grid is required. The calculated mean velocity, friction coefficient, and turbulence structure are in good agreement with available experimental data. In the region departed from the center of flow field, the contours of isojoint pdf of V₁ and V₂ is very similar to that of experimental result of channel flow. These agreements show the validity of the new pdf model and the availability of the boundary treatment and QUICKER scheme for solving the turbulent plane Couette flow.

The purpose of this paper is to investigate the relationship between the Chinese stock market indices and a set of macro‐economic variables, i.e. money supply, industrial production, inflation, exchange rate and interest rates.

The aims of this paper are addressed using heteroscedastic cointegration analysis.

Results show that the cointegrating relationship does exist between stock prices and the macro‐economic variables in the highly speculative Chinese stock market. Detailed analysis shows stock market performance is positively related to that of macro‐economy in the long term.

The results imply that in the long run, investors can benefit in terms of better returns and portfolio diversification as the Chinese economy is expected to continue to perform strongly.

The main contributions of this paper are two‐fold: first, this is the first paper to examine the long‐term relationship between the stock market indices and macro‐economic variables in China, one of largest economies in the world. Second, heteroscedastic cointegration analysis is used and hence this paper controls for time‐varying volatility.

The development, maintenance and improvement of quality efforts rest significantly on several internal and external enablers that encompass the building of quality infrastructure, changes in quality culture, transfer of technology, skills and management, integration of quality management practices, and so on. This paper reviews the contemporary quality concepts, and presents a glimpse into the major developments in the quality management domain in China. China’s experiences verified that the transformation process has gone through several phases, and finally attained the synergy of total quality management and compliance requirements of internationally recognized standards. China’s quality transformation efforts have been promoted through legislation and by the building of an institutional infrastructure. Moreover, the Chinese Government has played a directive role in shaping the context and institutional structure of Chinese enterprises and affecting the quality transformation efforts throughout the country.

In electronic commerce (EC), user interest reflects the behavior set of a users’ group acting on certain impulses. Electronic commerce web stations (ECWS) might be useful for intelligent information technology to create and refine the user interests database (UIDB) to make all kinds of service personalized. Usually two types of information should be included in UIDB. The first is contents of products or services and the second is forms for showing the contents. Both their structures are tangled trees. The issues about how to implement personalized service were investigated, the concepts of user interests and the structure of UIDB are defined, those about ECWS, how to create UIDB by user answers' selections, update and refine UIDB by user’s feedback information are discussed in detail in this paper. By means of UIDB, ECWS can actively recommend suitable series of pre‐sent web pages for different user groups and gradually arrive at their aim: offering personalized service for user groups.

It is quite possible that financial institutions including life insurance companies would encounter turbulent situations such as the COVID-19 pandemic before policies mature. Constructing models that can generate scenarios for major assets to cover abrupt changes in financial markets is thus essential for the financial institution's risk management.

The key issues in such modeling include how to manage the large number of risk factors involved, how to model the dynamics of chosen or derived factors and how to incorporate relations among these factors. The authors propose the orthogonal ARMA–GARCH (autoregressive moving-average–generalized autoregressive conditional heteroskedasticity) approach to tackle these issues. The constructed economic scenario generation (ESG) models pass the backtests covering the period from the beginning of 2018 to the end of May 2020, which includes the turbulent situations caused by COVID-19.

The backtesting covering the turbulent period of COVID-19, along with fan charts and comparisons on simulated and historical statistics, validates our approach.

This paper is the first one that attempts to generate complex long-term economic scenarios for a large-scale portfolio from its large dimensional covariance matrix estimated by the orthogonal ARMA–GARCH model.

The purpose of this paper is to construct an array of sensors using polypyrrole–zinc oxide (PPy–ZnO) and PPy–vanadium (V; chemical formula: V₂O₅) fibers. To test responses of sensors, a central composite design (CCD) has been used. The results of the CCD technique revealed that the developed sensors are orthogonally sensitive to diacetyl, lactic acid and acetic acid. In total, 20 different mixtures of diacetyl, lactic acid and acetic acid were prepared, and the responses of the array sensors were recorded for each mixture.

A response surface regression analysis has been used for correlating the responses of the sensors to diacetyl, lactic acid and acetic acid concentrations during the gas phase in food samples. The developed multivariate model was used for simultaneous determination of diacetyl, lactic acid and acetic acid concentrations. Some food samples with unknown concentrations of diacetyl, lactic acid and acetic acid were provided, and the responses of array sensors to each were recorded.

The responses of each sensor were considered as target response in a response optimizer, and by an overall composite desirability, the concentration of each analyte was predicted. The present work suggests the applicability of the response surface regression analysis as a modeling technique for correlating the responses of sensor arrays to concentration profiles of diacetyl, lactic acid and acetic acid in food samples.

The PPy–ZnO and PPy–V₂O₅ nanocomposite fibers were synthesized by chemical polymerization. The provided conducting fibers, PPy–ZnO and PPy–V₂O₅, were used in an array gas sensor system for the analysis of volatile compounds (diacetyl, lactic acid and acetic acid) added to yogurt and milk samples.

The purpose of the paper is to develop a method of automatic classification of the components of the assembly units. The method is crucial for developing an automatic ship assembly planning tools. The proposed method takes into account the assumptions specific for shipbuilding technology processes: high complexity of structures, difficult expert-based classification of components, fixed priority relations between connections resulting from geometrical constraints and demands of welding processes.

The set of ex post determined liaisons and assembly sequences constitutes the database of structures which have been made-up earlier. The components classification problem is solved using matrix coding of graphs. Information in such form is stored in the database. The minimization of number of cycles in the graph of classes sequence and minimization of diversity of classes within all constructions has been proposed as criteria of optimization. The genetic algorithm has been proposed as a solution method.

The proposed method solves the problem of components’ classifications. It allows setting the pattern of priorities between classes of various connections. This gives a chance to determine the relationship constraints between the connections of new structures for which assembly sequences are not established.

Mathematical formulation of the database is quite laborious. The possibility of partial automation of this process should be considered. Owing to the complexity of the problem, a relatively simple objective function has been proposed. During a ship hull assembly, additional criteria should be taken into account, what will be the direction of further research.

Automatic classification of components is dedicated for implementation in shipyards and similar assembly systems. Tests performed by the authors confirm efficiency of presented method in supporting management of the database and assembly of new structures planning. Suggested activity-oriented approach allows for easy conversion of any assembly unit structure to the form of a matrix.

The new approach for components classification according to its assembly features distinguishes the proposed method from others. The use of nilpotent matrix theory in an acyclicity of graphs analysis is also a unique achievement. Original crossover and mutation operators for assembly sequence were proposed in the article.