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The growing concern over the adverse effects of synthetic dyes has generated interest in the use of natural pigments by the food industry. β-carotene, a carotenoid found in various plant sources, is recognized for its antioxidant properties and provitamin A activity. The fruit of the buriti palm (Mauritia flexuosa), which is particularly rich in β-carotene, serves as a significant natural source of this pigment. This study aimed to extract β-carotene from buriti fruit using ionic liquids as an alternative to conventional organic solvents like acetone. β-carotene content was determined by HPLC and showed that extraction with [C4mim] [BF4] not only improved β-carotene extraction efficiency compared to acetone (19.21 and 13.13 mg/100 g, respectively) but also provided greater pigment stability during light, thermal and color stability tests. Moreover, ionic liquids are aligned with the principles of green chemistry and offer a sustainable and safe alternative for the food industry. Its favorable characteristics not only reduce environmental impacts associated with conventional solvents, but also ensure an increase in the shelf life of natural dyes, thus promoting the safety and quality of food products.

Structurally controlled slope failure in open-pit mining occurs when the shear stress acting on the geological structure exceeds its shear strength. Mining slope stability is an extremely important topic from the ramifications of safety, social, economic, environmental and regulatory factors. This study reports the engineering geological setting of a bedded mining slope in China, and evaluates its stability via a numerical approach. First, a slope profile model is constructed using a synthetic rock mass (SRM) modeling approach. More specifically, the mechanical behavior of colluvium, intact rock and discontinuities are represented by linear contact model, bonded particle model and smooth joint model, respectively. Then, the factor of safety (FOS) and instability process are investigated by integrating the discrete fracture network (DFN)-distinct element method (DEM) and strength reduction technique (SRT). In addition, shear stress analyses of colluvium and bedrock are conducted for revealing the potential failure mechanism. Finally, the well-established limit equilibrium (LEM) and finite element method (FEM) are adopted for simulation results comparison and validation.

The formation of geotechnical structures on foundations composed of low-strength soils is associated with a number of risks and difficulties. Soils such as clay-salt slurries are characterized by low bearing capacity and a tendency to deform under load. In this study, a numerical simulation of the stability analysis of an embankment constructed on low-strength soils consisting of clay-salt slurries is carried out, and the study of the dependence of the stability and behavior of the embankment on the configuration of this foundation, without taking into account the embedment of rocks and with introduction of rocks into the geotechnical system, is considered. The results prove that the sloping configuration of low-strength soils greatly complicates the stability of the embankment. It is noted that the stability factor is significantly reduced under the influence of loads on low-strength soil, particularly when the geotechnical system has a configuration with slope angles of 5° and 10°, and, in addition, when rocks are embedded in low-strength soil if the underlying soil layer is a weak foundation. In view of this, the assessment of embankment stability on clay-salt slurries requires careful analysis due to a number of specific characteristics of these soils that create complex geotechnical conditions.

The complex terrain and abundant ravines in the western mountainous areas of Beijing have led to dramatic changes in the geological environment. Monitoring and assessing the stability of landslide surfaces is of great significance for disaster prevention and ensuring the safety of the capital city. According to the spatial similarity characteristics of landslide surfaces, we propose a new interferometric synthetic aperture radar (InSAR) deformation enhancement method by taking into account the time-series deformation information of spatially adjacent homogeneous monitoring points. Taking Dongjiang Gully, Beijing as a typical study area, using multitemporal InSAR technology, 80 scenes of RADARSAT-2 data from September 2016 to September 2022 were processed to obtain their time-series surface deformation to verify the advantages of the proposed method. The results show that the standard deviation of the deformation difference of all monitoring points is generally reduced after the deformation enhancement, and the mean value is reduced from 5.1 to 3.3, which is 35.2% lower in comparison. Then this study assesses the stability of the landslide surface based on the deformation enhancement results. First, the optical image interpretation was combined with the angular distortions derived from deformation gradients to analyze the spatial location and boundaries of the landslide, and then to identify the infrastructure that is more susceptible to landslide impact. Second, through the principal component analysis method, the correlation between each component and the distribution characteristics of surface deformation was analyzed. Finally, starting from geological factors and triggering conditions, the driving force for landslide surface deformation was discussed, and it was drawn that seasonal precipitation is a major influencing factor. The proposed method can provide a reference for landslide monitoring and assessment in similar areas.

Reactive oxygen species (ROS), commonly known as free radicals, induced by UV radiation can compromise the dermal structure, leading to a loss of skin elasticity and subsequent wrinkle formation. A promising strategy to prevent and mitigate skin aging involves the use of topical formulations with potent antioxidant properties. Secondary metabolites such as astaxanthin and zeaxanthin are known for their robust antioxidant activities, which surpass those of tocopherol, offering significant benefits for skin health and protection against UV-induced damage. These properties suggest their potential application in anti-aging products. This study aims to evaluate the stability, ex vivo penetration, and in vivo efficacy of a radiance serum containing an astaxanthin–zeaxanthin nanoemulsion (AZ-NE) designed as an anti-wrinkle agent for topical application. The research was conducted in four stages: production of the astaxanthin–zeaxanthin nanoemulsion (AZ-NE), formulation of the AZ-NE radiance serum, stability, and efficacy testing. In this study, the formulated radiance serum demonstrated stability over three months under specified storage conditions. Ex vivo penetration studies indicated efficient diffusion of the active ingredients, with astaxanthin showing a penetration rate of 25.95%/cm2 and zeaxanthin at 20.80%/cm2 after 120 min. In vivo irritation tests conducted on human subjects revealed no adverse effects. Moreover, the serum exhibited substantial anti-wrinkle efficacy, with 15 female participants experiencing a wrinkle reduction of 80% to 93% over a 28-day period.

Rock slopes are usually reinforced by a number of rock bolts due to the high efficiency and low price. However, where should the rock bolts be installed is still a troublesome issue. For anti-dip bedding rock slopes (ABRSs), the installation position of rock bolts is a controlling factor that determines the reinforcement effect. In this work, a theoretical method is firstly proposed for assessing the stability of ABRSs reinforced by rock bolts using a limit equilibrium model. A comparison of theoretical calculations and numerical results was conducted to test the correctness of the theoretical method. Based on the stability assessment of ABRSs, we introduce adaptive moment estimation method (Adam) to optimize the installation location of rock bolts. Using Adam optimizer, the optimal layout of rock bolts with the maximum factor of safety can be determined, and the factor of safety of the slope increases by about 25% using the same amount of rock bolts but with different installation locations. The proposed method enables the fast stability analysis and supporting design for reinforced ABRSs, which paves the way to smart supporting design of slopes.

Abstract The social economy is growing rapidly, and the power grid load demand is increasing. To maintain the stability of the power grid, it is crucial to achieve accurate and rapid power system stability assessment. In the actual operation of the power network, data loss is an unavoidable situation. However, most of the data‐driven models currently used assume that the input data is complete, which has obvious limitations in real‐world applications. This paper suggests an IVS‐GAN model to assess power system stability using incomplete phasor measurement unit measurement data with random loss. The proposed method combines the super‐resolution perception technology based on generative adversarial network (GAN) with a time‐series signal classification model. The generator adopts a 1D U‐Net network and uses convolutional layers to complete and recover missing data. The discriminator adopts a new gated recurrent unit–attention architecture proposed here to better extract voltage temporal variation features on key buses. The result of this paper is that the stability evaluation method outperforms other algorithms in high voltage data loss rates on the New England 10‐machine 39‐bus system.

In response to the escalating demand for electric energy in the world, the maintenance technology for electric power equipment has evolved significantly. This study addresses the critical issue of insulation aging in high voltage equipment through an innovative approach. By integrating advanced Deep Q-networks (DQN) algorithms and intelligent data mining techniques, our proposed diagnostic scheme enables accurate and timely fault detection. The intelligent DQN algorithms process real-time equipment data, providing essential insights into operational status and faults. Implementing this research offers a strategic framework for enhancing the reliability of high-voltage equipment, contributing to stable system operation, and laying the groundwork for future advancements in equipment condition maintenance.

Effective disaster countermeasures of landslide dams hinge on the stability prediction in the emergency and mid-long-term stages. Variable morphological characteristics and multiple geomorphic indices as well as complicated geotechnical parameters pose significant challenges to a quick stability assessment. A particle size distribution (PSD) database was established based on 83 landslide deposits, including damming and non-damming landslides from around the world. Characteristic parameter K for quantitatively measuring landslide dam material properties were suggested on the basis of statistical analysis of deposit PSDs. Here we proposed a geotechnical index MMI (morphometry & material index) including dam volume, height and width, as well as characteristic parameter K, grain size d90 and lake volume that helps to estimate landslide dam stability. Besides, landslide dams in our inventory were divided into four levels based on their material composition, longevity and spillway form. With this we achieved the stability classification criterion according to the relation between these historical cases stability levels and MMI values. This study underlines the need to include geotechnical aspects such as grain size distribution for assessing dam stability, because the impact of material conditions on landslide dam evolution cannot be ignored.

Sounding rockets constitute a class of rocket with a generally simple layout, being composed of a cylindrical center-body, a nosecone, a number of fins placed symmetrically around the longitudinal axis (usually three or four), and possibly a boat-tail. This type of flying craft is typically not actively controlled; instead, a passive stabilization effect is obtained through suitable positioning and sizing of the fins. Therefore, in the context of dynamic performance analysis, the margin of static stability is an index of primary interest. However, the classical approach to static stability analysis, which consists in splitting computations in two decoupled domains, namely, around the pitch and yaw axis, provides a very limited insight to the missile performance for this type of vehicle due to the violation of the classical assumptions of planar symmetry and symmetric flight conditions commonly adopted for winged aircraft. To tackle this issue, this paper introduces a method for analyzing static stability through a novel index, capable of more generally assessing the level of static stability for sounding rockets, exploiting the same information on aerodynamic coefficients typically required for more usual (i.e., decoupled) static stability analyses, and suggests a way to assess the validity and shortcoming of the method in each case at hand.

In northern Campania (Southern Italy), the historic center of many towns is characterized by the widespread presence of cavities in the subsoil, excavated over the centuries for quarrying tuff blocks for buildings, along with cathedrals, churches and chapels. A singular feature of these places of worship is, in fact, the presence of a wide and frequently connected network of underground cavities and tunnels, which were used for hydraulic, religious or connecting purposes. The cavity network is often unknown, abandoned or even buried, thus representing a risk for their susceptibility to sinkholes. Such elements are important as cultural heritage of inestimable value and as attractors for tourism; for this reason, the multidisciplinary study conducted on a place of worship in the Caserta area is illustrated herein: the Cloister of Sant’Agostino, in Caserta (XVI century CE). A geological and geotechnical characterization of the subsoil was performed at first. A laser scanner survey of the accessible cavities and the external churchyard was carried out. The resulting 3D model of the underground sector allowed for a clear understanding of the room size, their location, the levels and the path of the corridors. To understand the extension and layout of the crypts, Electrical Resistivity Tomography (ERT) surveys were undertaken in the surrounding areas. The analysis of the ERT measurements revealed some anomalies that could be ascribed to unknown structures (crypts). Finally, numerical methods were applied to estimate the stress state of the soft rocks and the potential areas of crisis, with preliminary assessments of the influence of the presence of cavities on the stability of the subsoil. The results allowed us to improve the knowledge of the study site and provide useful data for the planning of future targeted investigations, underlining how integrated research between applied disciplines can provide indispensable support both in the management and mitigation of geological risks in urban areas and in the sustainable reuse of hypogea.

The integration of a high proportion of wind power has brought disorderly impacts on the stability of the power system. Accurate wind power forecasting technology is the foundation for achieving wind power dispatchability. To improve the stability of the power system after the high proportion of wind power integration, this paper proposes a steady-state deduction method for the power system based on large-scale wind power cluster power forecasting. First, a wind power cluster reorganization method based on an improved DBSCAN algorithm is designed to fully use the spatial correlation of wind resources in small-scale wind power groups. Second, to extract the temporal evolution characteristics of wind power data, the traditional GRU network is improved based on the Huber loss function, and a wind power cluster power prediction model based on the improved GRU network is constructed to output ultra-short-term power prediction results for each wind sub-cluster. Finally, the wind power integration stability index is defined to evaluate the reliability of the prediction results and further realize the steady-state deduction of the power system after wind power integration. Experimental analysis is conducted on 18 wind power farms in a province of China, and the simulation results show that the RMSE of the proposed method is only 0.0869 and the probability of extreme error events is low, which has an important reference value for the stability evaluation of large-scale wind power cluster integration.

Motivated by emerging HVDC oscillation issues resulted from the interaction with AC grids, impedance-based stability analysis has become an attractive approach in the de-risking studies due to the capability of black-box modelling and clear physical meaning. However, impedance-based stability assessment of HVDC is typically conducted either from the AC side or from the DC side, without fully considering both AC and DC grid dynamics, thus impairs evaluation accuracy. In this paper, the nodal admittance matrix based resonance mode analysis method is extended to include both AC and DC dynamics through formulating a hybrid AC/DC nodal admittance matrix. In contrast to the widely adopted Nyquist-based methods, the dynamic mode identification and damping ratio extraction using the frequency scanning of modal impedances derived from nodal admittance matrix is more straightforward for stability check, and the eigenvalue-decomposition based participation factor analysis is more useful in analyzing system wide dynamic interaction and identifying oscillation sources, which is in favor of the design of mitigation measures. The effectiveness of the described method is illustrated by case studies using a simple hybrid AC/DC grid consisting of converter-interfaced generation, synchronous machine and HVDC. Stability impacts of the strengths and modelling details of the connected AC grids for HVDC, the switching states of parallel AC line(s) for HVDC, and different modulation modes of HVDC converters are analyzed. It is observed, the AC-DC dynamic coupling can induce the interaction of the AC grids connected in different HVDC terminals. EMT-simulations in MATLAB/Simulink validate the analytical results.

Aimed at the lack of effective stability evaluation methods for the current steam power system, an operation stability assessment method suitable for single parameter is proposed. This method is a composite method, which first applied the midpoint and regression based empirical mode decomposition (MREMD) and singular value decomposition (SVD) to decompose the time series of operation parameters and extract their hidden trend terms. Then, the components are selected for reconstruction according to the optimal algorithm parameter permutation entropy (OAPPE) of each component. Finally, the auto-regressive integrated moving average (ARIMA ) model commonly used in the non-stationary time series analysis is utilized to predict the trend and the disturbance of parameters, and their distribution characteristics are also extracted in this process, based on which, the probability of instability (PI) of operation parameters at each point on the predicted trend are calculated, and their stabilities are quantitatively evaluated. The actual case proves that this method can effectively assess the operation stability of a single parameter of the steam power system, which has a certain theoretical innovation and engineering application value.

IMO stability regulations include various stability parameters such as GM values. To assess the stability of the ships, we should check all stability parameters of the IMO requirements. However, since this process is complex, a more convenient way to evaluate stability performance is required. In this research, the index for marine ship intact stability assessment (IMSISA) model was developed to solve these problems. The IMSISA model consists of a stability index calculation module and a stability assessment module. In the stability index calculation module, ten stability parameters, including GM, were used to develop the stability index, which has the advantage of being able to quantify the ship stability. The stability assessment module uses the stability index value to determine the stability status of the ship and provides the captain with stability management guidelines. To verify the proposed model, the basic stability calculations were performed for two model ships in 32 loading situations. The proposed model was found to provide better performance in the stability assessment than the previous study. By applying the IMSISA model to the ships, the captain can assess the ship stability more quantitatively and efficiently.

The failure mechanism of hard anti-inclined bedded rock slopes with the possibility of undergoing flexural toppling is very complex so that it is difficult to effectively perform their stability assessment. In this study, an attempt was made to accurately predict the stability factor and the failure surface of such slopes: establishing a new failure zone model and developing a limit equilibrium method based on this model. In this model, the failure zones of such a slope were divided strictly according to the failure mechanisms of the rock layers. In the presented method, the failure surface was considered to be a bilinear-type surface as observed in field investigations and laboratory tests, and the non-dimensional parameter indicating the position of application of the interlayer force was revised by deriving the distribution and the equivalent substitution of interlayer force. Then, a comparative study on Yangtai slope was performed to prove the presented method, and the effect of the non-dimensional parameter on the stability was also investigated. The results reveal that the presented method can accurately determine the failure surface and precisely evaluate the slope stability factor. In addition, the presented method has higher predictive accuracy compared with other analytical methods. With the decrease of the non-dimensional parameter, the stability of the slope is reinforced, but the larger landslide with more serious damage effect will occur if the slope undergoes the overall failure.

Bioconversion (e.g. anaerobic fermentation and compost) is the common recycling method of waste activated sludge (WAS) and its hydrolysis, as the rate-limiting step of fermentation, could be accelerated by protease. However, the commercial protease was unstable in a sludge environment, which increased the cost. An endogenous alkaline protease stable in sludge environment was screened in this study and its suitability for treating the sludge was analyzed. The optimal production medium was determined by Response Surface Methodology as starch 20 g/L, KH2PO4 4 g/L, MgSO4·7H2O 1 g/L, sodium carboxy-methyl-cellulose 4 g/L, casein 4 g/L and initial pH 11.3, which elevated the yield of protease by up to 15 times (713.46 U/mL) compared with the basal medium. The obtained protease was active and stable at 35 °C–50 °C and pH 7.0–11.0. Furthermore, it was highly tolerant to sludge environment and maintained high efficiency of sludge hydrolysis for a long time. Thus, the obtained protease significantly hydrolyzed WAS and improved its bioavailability. Overall, this work provided a new insight for enzymatic treatment of WAS by isolating the endogenous and stable protease in a sludge environment, which would promote the resource utilization of WAS by further bioconversion. HIGHLIGHTS A novel protease-producing bacterium was isolated from the sludge.; The screened protease was highly tolerant to the sludge environment.; Treatment of the sludge by the screened protease elevated its bioavailability.; The screened protease was a promising biocatalyst for sludge treatment.;

The unloading relaxation caused by excavation for construction of high arch dams is an important factor influencing the foundation's integrity and strength. To evaluate the degree of unloading relaxation, the long-short term memory (LSTM) network was used to estimate the depth of unloading relaxation zones on the left bank foundation of the Baihetan Arch Dam. Principal component analysis indicates that rock characteristics, the structural plane, the protection layer, lithology, and time are the main factors. The LSTM network results demonstrate the unloading relaxation characteristics of the left bank, and the relationships with the factors were also analyzed. The structural plane has the most significant influence on the distribution of unloading relaxation zones. Compared with massive basalt, the columnar jointed basalt experiences a more significant unloading relaxation phenomenon with a clear time effect, with the average unloading relaxation period being 50 d. The protection layer can effectively reduce the unloading relaxation depth by approximately 20%.

One of the most common critical areas of longwall mining in terms of ground stability are the gateroad and bleeder entries. These critical entries provide much-needed safe access for miners and allow for adequate ventilation required for dilution of hazardous airborne contaminants and must remain open during mining of a multi-panel district. This paper is focused on the stability of the longwall entries subjected to a single abutment load such as bleeders, first tailgate, and last headgate. First tailgate and last headgate are also referred to as blind headgate and tailgate. A study of a longwall district through conditions mapping, support evaluations, and numerical modeling was conducted and evaluated by researchers from the National Institute for Occupational Safety and Health (NIOSH). The condition mapping and support evaluations were performed on entries that spanned the previous five years of mining and relied on a diverse selection of supports to maintain the functionality of the entry. Numerical modeling was also conducted to evaluate various support types with further investigation and comparison to the condition mapping. The study demonstrated the importance of the abutment load decay versus distance from the gob edge, the potential for a reduction in material handling related injuries, as well as optimal usage of secondary and standing support.

Cave geotechnical studies have been the key to meeting the requirements of Brazilian environmental legislation for the conservation of speleological heritage in mining areas. This paper presents a methodology that classifies iron caves according to their susceptibility to structural instability called the Cave Geomechanical Index (CGI). This index combines four variables: (1) Rock Mass Rating (RMR), Bieniawski’ s geomechanical variable, which classifies the quality of the rock mass hosting the cave; (2) Hydraulic Radius (HR), an engineering variable that allows the dimension of the span to be evaluated; (3) Ceiling Shape (CS), a speleological variable that indicates whether the ceiling geometry of the cave spans is favorable or unfavorable for block formation, and (4) Ceiling Thickness (CT), a geotechnical variable that represents the depth between the ceiling of the cave and the surface of the ground regarding auto-support issues. The CGI was developed, applied and calibrated over four years, by monitoring 63 spans from 27 caves adjacent to active iron ore mines in Carajás, Pará state, Brazil, that had been authorized to be eliminated. This geomechanical classification system proved to be easy to implement and its results showed that 76% of the spans with breakdown occurrences in the caves were classified as high or very high susceptibility to structural instability, while 94% of the spans classified as low susceptibility did not show any signs of physical damage. The CGI is discussed with the focus on improving stability studies, predictability of cave breakdown mechanisms and geotechnical risk analysis of iron caves near mining operations.

The proliferation of Photovoltaic (PV) generation has brought several changes in the transient stability analysis of power systems. The rotor angle dynamics based stability analysis used for synchronous generators may not be applicable for PV generators. In the existing literature, the transient stability of a grid connected PV generator with dc link voltage and reactive power control (Vdc and Q control) is analyzed from the coupled nonlinear functions corresponding to PV control loops, Phase Locked Loop (PLL) and network dynamics. The existing method may not be suitable for online transient stability assessment because it is computationally heavy. This paper proposes an online transient stability criterion for a PV generator (with Vdc and Q control) connected to grid modelled as infinite bus. The PV generator is considered to have Low Voltage Ride Through (LVRT) capability, but does not provide voltage support. In this study, the relation between the ac and dc side dynamics is explored. A stability criterion is proposed to assess the transient stability by monitoring the swing in the energy of the dc link capacitor. The proposed criterion requires the dc link voltage trajectory only till the first swing of the dc link voltage. As a result, the proposed assessment criterion is computationally less demanding and less prone to measurement errors in comparison to existing methods. Thus, the proposed criterion is suitable for online transient stability assessment. The effectiveness of the proposed criterion is verified for single-stage as well as two-stage converter configurations of PV generator. The proposed criterion is also verified on a modified IEEE 39 bus system. Time-domain simulations are carried out to validate the proposed criterion. The proposed approach is compared with an existing transient stability criterion for Vdc and Q control based grid connected PV generator. The advantages of the proposed method as compared to the existing method are discussed.

Assessing the stability of the breakwaters against incident waves is the most important issue in structure designing. Due to this fact, the effects of different parameters on the stability of multi-layer berm breakwater (MLBBs) have been presented in this study. A 2D experimental model of an MLBB with a JONSWAP spectrum of irregular waves is conducted. The effects of berm parameters such as berm elevation from SWL and water depth at the toe of the structure have been evaluated on MLBBs damage. The new parameter of stone class I height is assessed to find its effect on MLBBs stability. Outcomes disclose that an increase in stone class I height would increase the wave energy dissipation and consequently decrease the structure’s damaged eroded area. Moreover, with a 23% increase in water depth, the forces on the structure would increase and as a result, the structural damage is enhanced to 250%. The results indicate as, with a 40% increase in berm elevation from SWL, the eroded area is enlarged to 67%.

The transition from power systems dominated by synchronous machines to systems based on converter-based generation technologies (CGTs), is weakening currently robust power systems by reducing system inertia with the replacement of synchronous generators with low-inertia CGTs. From a frequency stability viewpoint, this is resulting in faster frequency dynamics and more frequent and larger frequency excursions after system contingencies, thus significantly affecting the stability of power systems dominated by CGTs, requiring detailed stability assessments to ensure the secure integration of CGTs. In this paper, a practical framework is presented for frequency stability studies based on time domain simulations of power systems with CGTs. A fundamental part of the proposed approach is the use of a filter to first identify worst-case scenarios among various possible system operating conditions. Once these worst-case scenarios are identified, a clustering technique is used to select representative worst-case operating conditions to evaluate the frequency stability of the system using time-domain simulations. The effectiveness of the proposed framework is demonstrated on the Chilean Northern Interconnected System (NIS), where it is shown that the proposed filter is able to quickly identify worst-case scenarios for further study. Moreover, we show that the selected representative operating conditions cover a wide-range of worst-case frequency responses, demonstrating the effectiveness of the proposed tool for frequency stability analyses.

Although the deployment of alternating current (AC) -busbar plug-in electric vehicle (PEV) charging station with photovoltaic (PV) is a promising alternative, the interaction among subsystems always causes the instability problem. Meanwhile, the conventional generalized Nyquist criterion (GNC) is complex, and it is not suitable for the design of the AC system. Therefore, this paper proposes a modified infinity-one-norm (MION) stability criterion based on the impedance method to assess the stability of the foresaid charging station. Firstly, the typical structure and operation modes of the charging station are studied. Furthermore, each subsystem impedance matrix is built by small-signal method, and the MION stability criterion based on impedance method is proposed to assess the charging station stability. Compared with the previous simplified stability criteria based on the norm, the proposed criterion has lower conservatism. Furthermore, the design regulation for the controller parameters is provided, and the stability recovery way is provided by connecting the doubly-fed line and energy storage equipment, which are selected based on intermediate variable, i.e., short-circuit ratio (SCR). Finally, the effectiveness and conservatism of the proposed stability criterion are validated through simulation and experimental results.

A feature selection algorithm (FSA) is used to eliminate redundant and irrelevant features. Obviously, it can reduce dimensionality as well as the complexity of the original problem. Furthermore, the stability of FSA output becomes a major issue in real-world applications. Stability refers to the consistency of its feature preference related to the perturbation of data samples. In sensor array optimization, an FSA is used to find the best sensor combination in a sensor array. Typically, the main objectives of sensor array optimization are reducing data dimensions, electrical consumption, production cost, computational and traffic overhead, etc. Furthermore, the stable outputs of FSA in several observations are necessary to make a firm conclusion of selected sensors. The contribution of this research is to investigate the stability of FSAs in twelve homogeneous datasets in relation to the sensor array optimization problem. In this study, the stability of seventeen filter-based FSAs is compared across twelve homogeneous datasets. These datasets are generated from the electronic nose (e-nose) used to monitor twelve types of beef cuts. In this case, gas sensor array must have good generalization to differentiate all beef types. The experimental results show that a single FSA cannot guarantee stable sensors recommendation in sensor array optimization. Thus, it becomes a caution to researchers and practitioners to use a proper approach when performing sensor array optimization.

A proper assessment of the stability leads to proactive decision making for the method of construction, the shape and size of the cross-section of the facility and the adequate support. The stability is directly dependent on the physical, mechanical and technical characteristics of the rock mass. The traditional assessment-based approach and the classification of stability of underground facilities is based on both experience and experiments with previously constructed facilities. To ease the process for the early phase of design, there was a need for the development of a mathematical model for assessment of the stability. Ambiguity in mining engineering, directs the development of the model using a fuzzy logic system and fuzzy "if-then" rules. The model was developed based on very scarce input data that is most often the only data available during the design stage. Fuzzy model results have shown, through the random selection of input data in the model, that in 70% of cases, there is high numerical congruence with the traditional method for determination of coefficient of stability S; and in 90% of cases, there is also congruence in accordance with the traditional approach to the classification of underground facilities based on the stability assessment.

Purpose- Rural production cooperatives (RPCs) play an important role in sustainable development in rural areas by considering three principles: domination, possession, and agency in the agriculture sector. The purposes of this study are to measure the stability of RPCs and presenting effective strategies to achieve it from the managers’ view point. Design/methodology/approach- The present study is a mixed-research method using analytic-descriptive method, including two different questionnaires. One questionnaire aiming at prioritizing and measuring the stability of the RPCs was prepared and presented to the members of RPCs. Stability was measured with 24 indices in three economic, social, and environmental dimensions using Shannon Entropy technique, according which the cooperatives were prioritized. The other questionnaire was prepared to present the best approach to achieve sustainable development from the view point of the managing directors and the board of directors. The best strategy was adopted using SWOT and ANP analysis. Findings- Regarding the sustainable development, the findings of the study indicated that among rural production cooperatives in Isfahan, 12 cooperatives were unstable, 8 cooperatives were semi-stable, and 8 cooperatives were stable; this type of farming system is semi-stable. Developmental strategy (SO) was adopted as the best strategy to achieve sustainability, and the focus was on endogenous development through reinforcing internal strengths to obtain external opportunities. It includes promoting self-reliance through increasing members’ participation in cooperative, empowering the staff and members (i.e. the experienced managing director and the staff with required specialty and expert holding promotional classes), using multilevel, multi-sectorial, multi-cluster, collaborative, and holistic approaches to manage the RPCs, and promoting systems based on collaborative team work. Practical Implications- In rural sustainable development planning, sustainable farming systems must be considered as the focal core of any development plan. Since a big part of farming system in rural areas is devoted to smallholdings, promoting cooperation culture by the rural development planners can prepare the ground for empowering the villagers to obtain sustainable development. Originally/value: For the first time in Iran, the current research attempted to present functional strategies for RPCs development using a mixed-method design.

To evaluate the safety of passenger ships’ stability, ten stability parameters should be calculated. However, since the process for calculating all stability parameters is complex without a ship loading program, a convenient methodology to simply calculate them and evaluate the safety condition of a passenger ship is required to alert the hazard to a captain, officer, and crew. The Index for Passenger Ship Intact Stability Appraisal Module (IPSAM) is proposed herein. According to the value of a passenger ship’s metacentric height (GM) which could be calculated by the ship’s roll period measured by sensors in real-time, IPSAM simply calculates nine intact stability parameters except for AnglemaxGZ and proposes the present stability status as a Single Intact Stability Index (SISI). It helps crews easily recognize the safety of passenger ships’ stability as a decision support system in real-time. Based on the intact stability parameters of 331 loading conditions of 11 passenger ships, empirical formulas for IPSAM were derived. To verify the empirical formulas of IPSAM, the stability parameters of a passenger ship in 20 loading conditions were calculated using proposed empirical formulas and the principal calculation methods respectively, then compared. Additionally, the result of the SISI of 20 loading conditions successfully indicates the danger as the value of the SISI under 1.0 of the three loading conditions that do not satisfy the IMO intact stability requirements.

Securing a ship’s safe stability is essential. Thus, monitoring the stability parameters of the IMO requirements is required to provide an alert about the risk of the safety of ships’ stability to the captain, officers, and the crew of a ship. However, calculating all ships’ intact stability parameters is complex without ship loading software or equipment. To evaluate ships’ intact stability parameters, a convenient methodology to simply calculate them is necessary as a supplementary method for ships in the absence of loading software or equipment. In the present study, the Simple Evaluation Methodology for Intact Stability (SEMIS) is proposed. SEMIS is introduced for simply evaluating the safety of ships’ stability according to GM. Based on the stability parameters of 336 loading conditions of 19 model ships, empirical formulas of SEMIS are derived. To verify the proposed methodology, the stability parameters of two model ships in 28 loading conditions are calculated using the proposed empirical formulas and the principal calculation methods, respectively, and then compared. The developed SEMIS efficiently evaluates the ships’ stability using only GM.

An assessment of the stability and performance of current controllers with harmonic compensators is presented for an inductive-capacitive-inductive (LCL)-filtered grid-connected inverter under distorted weak grid conditions. By using two typical current control schemes which are the direct current controller with the capacitor current-based active damping and integral-resonant state feedback current controller, the closed-loop system stability and current control performance are investigated in the presence of both uncertain grid impedance and distorted grid. Even though the controller stability has been investigated under weak grid in several studies, the stability assessment of the entire current control scheme, including the harmonic resonant controllers, still needs a further comprehensive investigation. The system stability is analyzed by obtaining the movement of the closed-loop poles in the discrete-time domain when the grid impedance varies. To fully study the impact of distorted weak grid condition on the LCL filters, three LCL filter parameter sets giving the resonance frequency in different frequency bands are chosen for the purpose of evaluating the system robustness and grid-injected current quality. In order to support the presented theoretical analyses, comprehensive simulation and experimental results based on 32-bit DSP TMS320F28335 to control 2 kVA grid-connected inverter are presented in terms of grid current quality and control stability in the environment of both uncertain grid impedance and distorted grid.

This work evaluates the stability of the Boostan earth dam by investigating its long-term performance and interpreting the measured data. To measure the dam response, several sensitive locations are instrumented. This process includes measuring various quantities such as pore water pressure, water level, and internal stress ratios using inspection devices such as ordinary and Casagrande piezometers, and total pressure cells. The recorded data shows that the pore pressure is in good agreement with the initial (stable) design condition. The installed piezometers show that the drainage is efficient, and the water table in the body is adequate. The instrument also shows a reasonable horizontal stress in the dam body. Overall, the condition of the case study dam is assessed to be normal. The results of this case report can be used as a guide in similar dams for instrumented health monitoring.

In this paper, dynamic analysis of a multi-battery dual mode charger, powered by a single solar array and suitable for lead-acid and lithium-ion cell-based batteries is presented. Each battery is interfaced to the solar array by means of a current-controlled buck power stage, operating either in constant power or constant voltage mode. Operation in former/latter charging mode implies regulating input/output voltage of the converter, which is a non-trivial situation since while feeding different batteries, all the converters share the same input terminals, connected to the solar array. It is revealed that when at least one of the batteries operates in constant power charging mode, open-loop instability occurs whenever converter input voltage is lower than maximum power point voltage of the solar array. Consequently, input voltage regulating controller must be designed to stabilize closed-loop dynamics for the worst case of instability, which is also derived. Moreover, it is shown that the dynamics of the converters operating under output voltage control are perceived as disturbances by input voltage control loop and must be properly rejected. Simple loop shaping design is proposed based on a PI controller, allowing stabilizing the system in case of worst case instability and rejecting output voltage control induced disturbances at the expense of non-constant, operating-point dependent closed-loop damping.

Torsional oscillations and stability assessment of the homokinetic Cardan shaft with a small misalignment angle is described in this paper. The simplified mathematical model of this system leads to the linearized equation of the Mathieu's type. This equation with and without a stationary damping parameter is considered. The solution of the original differential equation is identical with those one of the Fredholm’s integral equation with degenerated kernel assembled by means of a periodic Green's function. The conditions of solvability of such problem enable the identification of the borders between stability and instability regions. These results are presented in the form of stability charts and they are verified using the Floquet theory. The correctness of oscillation results for the system with periodic stiffness is then validated by means of the Runge-Kutta integration method.

The stability number of a breakwater can determine the armor unit’s weight, which is an important parameter in the breakwater design process. In this paper, a novel and simple machine learning approach is proposed to evaluate the stability of rubble-mound breakwaters by using Extreme Learning Machine (ELM) models. The data-driven stability assessment models were built based on a small size of training samples with a simple establishment procedure. By comparing them with other approaches, the simulation results showed that the proposed models had good assessment performances. The least user intervention and the good generalization ability could be seen as the advantages of using the stability assessment models.

This paper proposes an overall practical stability assessment for a multi-port single-phase solid-state transformer (MS3T) in the electromagnetic timescale. When multiple stable subsystems are combined into one MS3T, the newly formed MS3T has a certain possibility to be unstable. Thus, this paper discusses the stability assessment of the MS3T in detail. First and foremost, the structure of the MS3T and its three stage control strategies are proposed. Furthermore, the stability analysis of each of the MS3T’s subsystems is achieved through the closed loop transfer function of each subsystem, respectively, including an AC-DC front-end side converter, dual active bridge (DAB) with a high-frequency (HF) or medium-frequency (MF) transformer, and back-end side incorporating DC-AC and dc-dc converters. Furthermore, the practical impedance stability criterion in the electromagnetic timescale, which only requires two current sensors and one external high-bandwidth small-signal sinusoidal perturbation current source, is proposed by the Gershgorin theorem and Kirchhoff laws. Finally, the overall stability assessment, based on a modified impedance criterion for the MS3T is investigated. The overall practical stability assessment of the MS3T can be validated through extensive simulation and hardware results.