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Proposes an object‐oriented role‐based access control (ORBAC) model to efficiently represent the real world. Though ORBAC is a good model, administration of ORBAC, including creating and maintaining an access control security policy, still remains a challenging problem. Presents a practical method that can be employed in an enterprise environment to manage security policies using eXtensible Markup Language (XML). Based on ORBAC security policy expressed in XML, a role assignment algorithm is presented. The computation complexity of the algorithms is O(N) where n is the number of position roles in a user’s assigned position role scope.

Information flow analysis is a necessary step to determine the information security for a given system. In this paper, we introduce an object oriented role‐based access control model (ORBAC) and illustrate that the confinement problem may occur on the ORBAC based system. In order to deal with the problem, a technique called information flow analysis is proposed. Moreover, under the principle of mandatory access control (MAC) security policy, a role set assignment method is developed and proved to solve the confinement problem on ORBAC.

This paper aims to study the oscillation phenomenon before chaos as well as its mechanism of occurrence in the energy-saving and emission-reduction system.

The system dynamics analysis, phase portrait analyses, equilibrium point analysis and bifurcation curve were applied to this paper.

First, the authors find an oscillation phenomenon previous to chaos. Second, on the one hand, the existence of two unstable saddles is the reason for the occurrence of oscillation phenomenon. On the other hand, the increasing of carbon emissions can arouse oscillation phenomenon.

This paper finds an oscillation phenomenon previous to chaos in the energy-saving and emission-reduction system. The mechanism of occurrence of oscillation phenomenon is studied. The existence of two unstable saddles is the reason for the occurrence of such oscillation phenomenon. The oscillation is related with fold bifurcation. The study also provides a theoretical basis for the further study of chaos control.

Recent studies have shown that hyperuricemia is a predictor of non-communicable disease and an increment of mortality rate. Also, elevated serum uric acid may be associated with obesity in the adult population. This study aims to evaluate the association between serum uric acid levels with metabolic parameters and risk of obesity in the Iranian population.

The cross-sectional study was done on 550 participants, who were referred to a hospital for elective angiography in Rasht, Iran; anthropometric indices (waist circumference (WC) and body mass index (BMI)) and hematological factors were measured using the standard approaches. Based to the angiography results, the severity of atherosclerosis was defined.

The mean (SD) concentration of serum uric acid for all participants was 5.15 (1.37) mg/dl. Individuals who were at the highest tertile had higher mean (SD) of weight (p = 0.004), creatinine and blood urea nitrogen (p < 0.001) lower fasting blood sugar (FBS) (p = 0.000) and HbA1c (p = 0.016), and they were mostly men compared with those in the lowest tertile. After adjusting for confounders, FBS (ß = –0.145, p = 0.001) and HbA1c (%) (ß = –0.130, p = 0.019) had inverse and weight (ß = 0.156, p = 0.001) had direct association with serum uric acid. After adjustment for additionally potential confounders subjects in the highest tertile of serum uric acid had 92 per cent higher chance of obesity compared with subjects in the lowest tertile (OR 1.92; 95 per cent CI 1.13, 3.23).

The present study has concluded that increase serum uric acid related to high risk of obesity and low mean of FBS and HbA1c.

Managing the growing word-of-mouth (WOM) of brand fans has become a new challenge for companies in the fan economy era. The purpose of this paper is to examine the effect of language intensity of brand fan WOM on customers' willingness to adopt WOM based on psychological resistance theory and to reveal the underlying mechanism of this process.

A research model was developed to test the proposed hypotheses. Two experiments were conducted on an online platform using data from 708 participants. The independent samples t-test and analysis of variance were used to analyze the data.

The results show that, in the context of WOM among brand fans, high-intensity language leads to a lower willingness to adopt than low-intensity language and threats to freedom mediate this effect. Moreover, the restoration postscript moderates the effect of language intensity on threats to freedom and customers' willingness to adopt WOM.

Unlike previous studies that focused on electronic word-of-mouth (eWOM) language content, this paper focuses on language intensity to reveal the psychological process of customers' willingness to adopt brand fan WOM. The findings not only enrich the research related to the language effect in eWOM, but also deepen the understanding of the influence effect on brand fan WOM, providing effective guidance for brands to manage fan WOM.

In this study, response surface methodology (RSM) is applied to a three-point bending stiffness analysis of low-cost material (PLA) specimens printed using FDM technology to analyze the performance of different internal lattice structures (Octet and IsoTruss principally). The purpose of this study is to extend the definition from a discrete (lattice) model to an analytical one for its use in subsequent design phases, capable of optimizing the type of cell to be used and its defining parameters to find the best stiffness-to-weight ratio.

The representative function of their mechanical behavior is extrapolated through a two-variable polynomial model based on the cell size and the thickness of the beam elements characterizing it. The polynomial is obtained thanks to several tests performed according to the scheme of RSM. An analysis on the estimation errors due to discontinuities in the physical specimens is also conducted. Physical tests applied to the specimens showed some divergences from the virtual (ideal) behavior of the specimens.

The study allowed to validate the RSM models proposed to predict the behavior of the system as the size, thickness and type of cells vary. Changes in stiffness and weight of specimens follow linear and quadratic models, respectively. This generally allows to find optimal design points where the stiffness-to-weight ratio is at its highest.

Although the literature provides numerous references to studies characterizing and parameterizing lattice structures, the industrial/practical applications concerning lattice structures are often still detached from theoretical research and limited to achieving functioning models rather than optimal ones. The approach here described is also aimed at overcoming this limitation. The software used for the design is nTop. Subsequent three-point bending tests have validated the reliability of the model derived from the method’s application.

This study aims to report the CO₂ corrosion performance of 3Cr steel and 3Cr2Al steel and reveal the role of aluminum in mitigating corrosion of low-Cr steel.

Aluminum was added to 3Cr steel to prepare a new type of 3Cr2Al steel, and the effect of aluminum on the corrosion resistance of pipeline steel was studied using morphology observation and composition analysis, weight loss tests and electrochemical test.

In the CO₂/O₂ coexistence environment, the average corrosion rate of the 3Cr2Al steel was obviously lower than that of the 3Cr steel. The addition of aluminum expanded the range of prepassivation, and the dynamic potential polarization curve of 3Cr2Al steel showed duplex prepassivation phenomena. 3Cr steel underwent severe local corrosion, and 3Cr2Al steel underwent uniform corrosion. The addition of aluminum contributed to the formation of a dense corrosion product layer and greatly reduced the localized corrosion sensitivity.

The studies on CO₂ corrosion of aluminum containing low-Cr steel are quite rare. This study clarifies the role of aluminum by comparing the corrosion behavior of 3Cr2Al and 3Cr steel. The effect of aluminum on the growth of corrosion product film was discussed, and the duplex prepassivation phenomena of Cr and Al were revealed.

The rail transport sector in China represents one of the largest consumers of energy today, and the primary purpose of this paper is to examine the causes of changes in energy consumption of Chinese national rail transport (ECCNRT).

For this study, reasonable indicators as factors that affected conversion volume (CV) and unit energy consumption (UEC) based on statistical data from 1990 to 2010 were selected. CV and UEC models were established by regression analysis and tested using real data of 2011-2014. The CV model indicates it has an exponential relationship with GDP. Besides, there is a quantitative relationship between UEC and the quantity of locomotives. The ECCNRT calculation model was proposed and ECCNRT model data were compared with the real data. Impacts of different factors on ECCNRT were analyzed with economic principles.

The analysis conducted shows that the calculation model can reflect variation of ECCNRT precisely, and ECCNRT has a quantitative relation with GDP and quantities of locomotives. GDP accounts for changes of ECCNRT 20.02 per cent, while those for quantity of diesel locomotives and electric locomotives are 26.87 and 53.11 per cent, respectively. The number of electric locomotives is the main factor that influences variation of ECCNRT.

Through regression analysis, this study discovered the inner quantitative relationship between the conversion volume (important index of Chinese national rail transport production) and GDP. In addition, this study establishes the ECCNRT model according to the Chinese national rail transport data, which can be used to calculate the amount of ECCNRT and conduct quantitative analysis for different impacts of various factors on ECCNRT’s changes.

This paper aims to address the challenges in hydroacoustic signal detection, signal distortion and target localization caused by baseline drift. The authors propose a combined algorithm that integrates short-time Fourier transform (STFT) detection, smoothness priors approach (SPA), attitude calibration and direction of arrival (DOA) estimation for micro-electro-mechanical system vector hydrophones.

Initially, STFT method screens target signals with baseline drift in low signal-to-noise ratio environments, facilitating easier subsequent processing. Next, SPA is applied to the screened target signal, effectively removing the baseline drift, and combined with filtering to improve the signal-to-noise ratio. Then, vector channel amplitudes are corrected using attitude correction with 2D compass data. Finally, the absolute target azimuth is estimated using the minimum variance distortion-free response beamformer.

Simulation and experimental results demonstrate that the SPA outperforms high-pass filtering in removing baseline drift and is comparable to the effectiveness of variational mode decomposition, with significantly shorter processing times, making it more suitable for real-time applications. The detection performance of the STFT method is superior to instantaneous correlation detection and sample entropy methods. The final DOA estimation achieves an accuracy within 2°, enabling precise target azimuth estimation.

To the best of the authors’ knowledge, this study is the first to apply SPA to baseline drift removal in hydroacoustic signals, significantly enhancing the efficiency and accuracy of signal processing. It demonstrates the method’s outstanding performance in the field of underwater signal processing. In addition, it confirms the reliability and feasibility of STFT for signal detection in the presence of baseline drift.

This study examines the influence of stock liquidity on stock price crash risk and the moderating role of institutional blockholders in Vietnam’s stock market.

Crash risk is measured by the negative coefficient of skewness of firm-specific weekly returns (NCSKEW) and the down-to-up volatility of firm-specific weekly stock returns (DUVOL). Liquidity is measured by adjusted Amihud illiquidity. The two-stage least squares method is used to address endogeneity issues.

Using firm-level data from Vietnam, we find that crash risk increases with stock liquidity. The relationship is stronger in firms owned by institutional blockholders. Moreover, intensive selling by institutional blockholders in the future will positively moderate the relationship between liquidity and crash risk.

Since stock liquidity could exacerbate crash risk through institutional blockholder trading, firm managers should avoid bad news accumulation and practice timely information disclosures. Investors should be mindful of the risk associated with liquidity and blockholder trading.

We contribute to the literature by showing that the activities of blockholders could partly explain the relationship between liquidity and crash risk. High liquidity encourages blockholders to exit upon receiving private bad news.