Original Scheme Research Articles

A seventh-order accurate weighted compact scheme for shock-associated noise computation

High-fidelity computation of shock-associated noise places stringent requirements on the accuracy, linear and nonlinear spectral properties of shock-capturing scheme. In this paper, a novel weighted nonlinear compact scheme with seventh-order accuracy is developed for the purpose of improving the linear and nonlinear spectral properties of original scheme (Zhang et al., (2008) [1]). The numerical fluxes at cell centers are obtained using upwind-biased weighted nonlinear interpolation based on the new S-type smoothness indicator that be constant for sine and cosine functions (Wu et al., (2020) [2]). Through systematic spectral analysis and numerical experiments, it is demonstrated that the newly proposed scheme has very weak nonlinear effect and reduces the dissipation and dispersion at the medium and high wavenumbers. The resolution for the short waves and the fine-scale structures is improved. It has the potential to become a suitable candidate for the computation of shock-associated noise.

Influence of Atmospheric Non-Uniform Saturation on Extreme Hourly Precipitation Cloud Microphysical Processes in a Heavy Rainfall Case in Zhengzhou

Heavy rainfall not only affects urban infrastructure, it also impacts environmental changes, and which then influence the sustainability of development and ecology. Therefore, researching and forecasting heavy rainfall to prevent disaster-related damages is essential. A high-resolution numerical simulation was carried out for a heavy rainfall case in Zhengzhou, Henan Province, China, from 19–20 July 2021. The analysis of weather conditions revealed that the main cause of heavy rainfall in Zhengzhou was the supersaturation and condensation of water vapor, resulting from the invasion of dry and cold air from the upper and middle atmospheric layers. This weather condition is ideally suited for applying generalized potential temperature that is informed by the non-uniform saturation theory. Based on this, the new scheme revised the cloud microphysical scheme of the cloud water condensation parameterization process by substituting generalized potential temperature. The characteristics of the mesoscale environment and water condensates were comparatively analyzed between the original and the new scheme. Then, the quantitative mass budget and latent heat budget related to microphysical conversions were comparatively calculated over Zhengzhou. Furthermore, the possible two-scheme mechanisms through which the cloud microphysics processes affected the rainfall were investigated and discussed. It was found that: (1) The new scheme, which takes into account generalized potential temperature, produced precipitation fields more in line with observations and simulated stronger hourly precipitation compared to the original scheme. (2) The conversions of snow were the main source of microphysical processes that produced precipitation and released latent heat due to the dry and cold air invasion. (3) Given that the condensation of water vapor was hypothesized to occur at 70% relative humidity (RH) or above, rather than the original 100% RH, the new scheme simulated more supercooled water and ice-phase particles than the original scheme. This enhancement, in turn, intensified convective development owing to positive feedback within the cloud microphysics processes and cloud environment, ultimately leading to the simulation of more intense hourly precipitation.

Evaluation of Ten Fresh Snow Density Parameterization Schemes for Simulating Snow Depth and Surface Energy Fluxes on the Eastern Tibetan Plateau

Snow cover on the Tibetan Plateau has a shallow depth, plaque distribution, and repeated ablation. The applicability of the snow parameterization scheme in the current land surface process model on the TP needs to be further tested using observational data. In this paper, using the land surface process model CLM4.5 and ten fresh snow density parameterization schemes characterized by temperature, wind speed, and relative humidity, three discontinuous snow processes in Maqu, Madoi, and Yakou and two continuous snow processes in Madoi and Yakou were simulated. By comparing the simulated snow depth with the observed, it was found that this model can clearly describe repeated snow accumulation and ablation processes for the discontinuous snow cover process. The KW scheme, compared with the original Anderson scheme, performed the best regarding snow depth simulation. However, all schemes overestimated the melting rate of snow, and were not able to simulate continuous snow accumulation. The simulation effect of the Schmucki scheme on radiation and energy flux under discontinuous snow cover was significantly improved compared with other scheme. None of schemes performed perfectly, so future studies that focus on the simulations of snow depth, radiation flux, and energy flux under continuous snow cover for accurate and wide applications are recommended.

Rational reparameterization of unstructured quadrilateral meshes for isogeometric analysis with optimal convergence

Unstructured quadrilateral meshes are widely used in representing surfaces of arbitrary topology. However, in connection with isogeometric analysis, unstructured meshes suffer from sub-optimal convergence rates in extraordinary regions, especially for solving higher-order PDEs (partial differential equations). In this work, a rational reparameterization method is proposed to achieve optimal convergence rates for isogeometric analysis using Catmull-Clark surfaces. The scheme lifts the convergence of analysis solutions by tuning the weights of control vertices of the input geometry in extraordinary regions, which are often neglected in constructing analysis-suitable parameterizations. Preferred tuning parameters with optimal convergence rates in L2-norm are determined statistically based on a test suite composed of typical testing solutions with a range of parameters. Numerical experiments confirm the validity of the proposed method for PDEs up to the fourth-order. Comparisons with the original Catmull-Clark scheme and a state-of-the-art tuned subdivision scheme also show the superiority of the proposed method in terms of both optimal convergence and reduced absolute errors of resulting analysis solutions.

Thermal comfort performance prediction method using sports center layout images in several cold cities based on CNN

Sports centers are core spaces for urban sports and fitness, and reasonable layout of large public buildings can alleviate urban climate issues. But the adverse effects of planning and layout and surrounding urban microclimate on the thermal comfort of outdoor activity space are rarely considered. In this study, an EnergyPlus and Openfoam collaborative computing platform was constructed to calculate the universal thermal climate index of the outdoor space of sports center. By comparing the simulation results of sports centers in three severely cold cities, improving the wind environment of the site's microclimate was found to be key in improving thermal comfort, and the hours of overall site thermal comfort increased mainly in spring and autumn. In this paper, a design method combining numerical simulations and a convolutional neural network was proposed, which can effectively predict the thermal comfort performance of affected sites. The application of this prediction method to the design of the Yingkou Sports Center increased the hours of overall site thermal comfort by 15.01% compared with the original scheme. Synthesizing the results and methods of this study can provide an effective reference and analysis tool for the overall environmental performance of urban areas.

Q-learning based multi-objective immune algorithm for fuzzy flexible job shop scheduling problem considering dynamic disruptions

Confronted with complex industrial environments, dynamic disruptions like new job arrival and machine breakdown bring significant challenges to the robustness and stability of the manufacturing process, making the static production depart from the original scheduling scheme. To address this problem, a flexible job shop scheduling problem with fuzzy processing time, dynamic disruptions, and variable processing speeds is considered simultaneously. As well as three objectives of maximum completion time, total energy consumption, and average agreement index are demonstrated in this study. Then, a predictive-reactive dynamic/static rescheduling model is developed, where the off-line based mixed integer linear programming model and the on-line based rescheduling heuristics are proposed. Next, a multi-objective immune algorithm combined with a Q-learning algorithm (Q-MOIA) is developed. In the proposed algorithm, an active decoding heuristic based on the interval insertion mechanism is used to optimize the initial solutions. After that, the clonal selection-based immune algorithm and the Q-learning algorithm are adopted to improve the exploration and exploitation capabilities, respectively, where four objective-driven neighborhood structures are designed. Eventually, extensive computational experiments were conducted on 27 instances under static and dynamic scenarios to demonstrate the superiority and stability of the proposed predictive-reactive dynamic/static rescheduling model and the Q-MOIA. Comparative analysis with four state-of-the-art approaches revealed that proposed Q-MOIA outperformed in approximately 51.9, 66.7, and 83.3 % of the instances for the three multi-objective metrics.

Design optimization of a Dual-Interlocked-Cell in 65 nm CMOS tolerant to Single Event Upsets

Dual-Interlocked-Cell (DICE) latches are tolerant to Single Event Effects (SEE) by design owing to intrinsic redundancy. In nanometric technologies, as in the 65 nm scale, there are new SEE vulnerabilities associated with charge sharing between nodes. Herein we present a systematic analysis of the robustness against radiation using a simulation software tool for analog and mixed-signal circuits (AFTU) that emulates the possible effects generated by particle impacts. In this paper, we evaluate the influence of SEE on circuit performance using this tool as an RHbD assessment for designers. An exhaustive study of the possible vulnerabilities of the DICE architecture is performed, including an evaluation of the proximity between critical nodes at the layout level. As a result, we propose several modifications to the cell implementation to optimize its robustness against Single Event Upsets (SEU). An assortment of five designs with different variations of the original DICE scheme was sent for fabrication on a new chip and tested under ion beams, with promising results showing a clear improvement in the SEU sensitivity of the cell. The best results come from a redesign of the load circuitry to avoid a SET2SEU effect and full interleaved layout to avoid charge sharing effects after a single event.

INTRAUTERINE INFECTIONS: A MODERN VIEW AT THE PROBLEM

The work summarizes both the results of many years of research by the author and his collaborators, and the ideas available in the literature. The principles of classification of intrauterine infections (IUI) and approaches to their laboratory and morphological diagnosis are discussed. Original schemes for various infection options are presented. Characteristics of both the most well-known and less studied etiological formsof IUI are given.

Application of improved multi objective particle swarm optimization and harmony search in highway engineering

Highway engineering construction is a complex multi-objective management project, and the traditional multi-objective task management approach has been difficult to cope with the uniqueness of highway engineering construction management. In order to improve the efficiency of multi-objective management in highway engineering, the study proposes to construct a multi-objective management model using particle swarm and harmony search algorithms for highway engineering management. First of all, the study first explores the management indexes in highway engineering, and constructs the functional relationship according to the selected indexes. Then the particle swarm algorithm is used to optimize the database of the harmonic search algorithm, and the harmony search algorithm can be based on the optimized database to find the optimal solution for objective management. The experimental results show that the improved particle swarm and harmony search algorithm has good distribution and convergence. After the optimization of the proposed model, the multi-objective highway project management scheme is 39% ahead of schedule, 17% savings in input funds, and 2.56% and 3.56% improvement in highway quality indexes and ecological environment management indexes, respectively, compared with the original scheme. Therefore, the model has a good application prospect to formulate the optimal multi-objective management scheme with excellent performance to improve the management efficiency of highway engineering.

Generative design: Integrating rent and retail compatibility goals for automated tenant mix layout

Tenant mix is a central issue in the development and operation of shopping malls. An effective tenant layout can enhance the consumer experience and increase shop sales. So it is crucial to comprehensively consider the rent and retail compatibility when crafting the tenant mix. Developers mainly considered the rent income from anchor and non-anchor tenants. But many studies ignored the externality effect of anchor tenants on the rent of non-anchor tenants. Furthermore, the relationship between different tenant type and retail compatibility under customers' behavioral preferences is not adequately studied. In addition, existing optimization methods is inefficient, poorly integrated and cannot rapidly explore design options. Therefore, this paper aims to achieve automatic generation and optimization of tenant mix layouts considering the rent and retail compatibility objective. Firstly, a bi-objective model consisting of the rent and retail compatibility objectives is developed to evaluate the performance of the generated schemes. The rent objective function quantifies the externality of anchor shop on the rent of non-anchor shops in the shopping center. The retail compatibility function quantifies the relationship between the consumers’ behavior preferences and retail types. Then this paper proposed a generative mechanism consisting of parametric design, scheme optimization and decision making processes. The results of the case study show that the optimized scheme outperforms the original scheme in terms of both rent and retail compatibility objectives. The proposed generative mechanism achieves automatic generation and optimization of tenant mix layouts, and greatly improves the efficiency of the design process.

Rarefaction and extrapolation with beta diversity under a framework of Hill numbers: The iNEXT.beta3D standardization

AbstractBased on sampling data, we propose a rigorous standardization method to measure and compare beta diversity across datasets. Here beta diversity, which quantifies the extent of among‐assemblage differentiation, relies on Whittaker's original multiplicative decomposition scheme, but we use Hill numbers for any diversity order q ≥ 0. Richness‐based beta diversity (q = 0) quantifies the extent of species identity shift, whereas abundance‐based (q > 0) beta diversity also quantifies the extent of difference among assemblages in species abundance. We adopt and define the assumptions of a statistical sampling model as the foundation for our approach, treating sampling data as a representative sample taken from an assemblage. The approach makes a clear distinction between the theoretical assemblage level (unknown properties/parameters of the assemblage) and the sampling data level (empirical/observed statistics computed from data). At the assemblage level, beta diversity for N assemblages reflects the interacting effect of the species abundance distribution and spatial/temporal aggregation of individuals in the assemblage. Under independent sampling, observed beta (= gamma/alpha) diversity depends not only on among‐assemblage differentiation but also on sampling effort/completeness, which in turn induces dependence of beta on alpha and gamma diversity. How to remove the dependence of richness‐based beta diversity on its gamma component (species pool) has been intensely debated. Our approach is to standardize gamma and alpha based on sample coverage (an objective measure of sample completeness). For a single assemblage, the iNEXT method was developed, through interpolation (rarefaction) and extrapolation with Hill numbers, to standardize samples by sampling effort/completeness. Here we adapt the iNEXT standardization to alpha and gamma diversity, that is, alpha and gamma diversity are both assessed at the same level of sample coverage, to formulate standardized, coverage‐based beta diversity. This extension of iNEXT to beta diversity required the development of novel concepts and theories, including a formal proof and simulation‐based demonstration that the resulting standardized beta diversity removes the dependence of beta diversity on both gamma and alpha values, and thus reflects the pure among‐assemblage differentiation. The proposed standardization is illustrated with spatial, temporal, and spatiotemporal datasets, while the freeware iNEXT.beta3D facilitates all computations and graphics.

Grid-scale crop dynamic layout optimization model considering stakeholders' cropping preferences and practice behaviours

Rapid population growth has led to an increasing demand for food, accompanied by an increase in the resources invested in producing food, and the extensive food production practices have placed a huge burden on the environment. There is an urgent desire of need to find a sustainable model of food production. Therefore, this study attempted to develop a dynamic regional grid-scale crop layout model (ABCAMODP-Crop) combining agent-based model, multi-objective programming, dynamic programming and cellular automata model to promote more sustainable food production from a supply-side perspective. The model can: (1) take into account the planting preferences and practical behaviours of government and farmer as stakeholders in crop layout; (2) further weigh the conflicts among the various objectives that stakeholders are concerned with from resource, environmental, nutritional and economic dimensions; (3) consider the impact of the previous year's crop layout on the next year's crop placement; and (4) obtain grid-scale accurate crop layout solutions by considering the spatial variability of optimization parameters and the neighborhood effects of crop layout cells. The model was applied to the Shiyang River Basin in China to verify its usefulness. Over the entire planning period, crop layout schemes optimized with the objective of integrating irrigation water productivity, environmental impact, nutrient availability and economic benefits have higher comprehensive benefits than the original scheme, with an increase in average irrigation water productivity per unit area of 14.55%, an increase in total yield of 14.45%, an increase in total carbohydrate availability of 7.39%, an increase in total calcium availability of 18.74%, an increase in total net carbon sequestration of 8.05%, an increase in total net benefit of 20.08%. The model developed allows for a holistic view of crop layout and guides decision-makers in a rational distribution of regional crops, thus promoting more sustainable food production. It can equally be extended to other regions as a generic modelling framework.

Study on the High Strength Cable Truss System Control of the Surrounding Coal Roadway Excavated in Regions Left Intensively Mining-Induced Stresses

In coal mine roadway support, the arrangement of roadways in areas with high-stress concentrations is a challenging issue. It is crucial to solve this problem in order to ensure the safety and productivity of the mine. In this study, we selected a typical roadway in Zhong Xing Coal Mine, Fen Xi, Shanxi Province, as our research focus. We analyzed the deformation and failure characteristics of the surrounding rock under field mining pressure during roadway excavation through theoretical analysis, numerical simulation, and on-site measurements. Using the Flac3D numerical simulation technique, we studied the stress distribution characteristics of the roadway in the stress concentration area. To address the significant deformation of the roadway, we proposed a high-pretensioned top beam high-strength dual-anchor truss support system (HSCTS) and carefully studied its control mechanism and structural characteristics. After simulating and comparing its support effectiveness with the original support scheme and conducting on-site industrial tests, we determined the HSCTS support system as the alternative support system for roadway 1409. The test results showed that the convergence of the rib plates and the roof was no more than 79 mm and 191 mm, respectively. The significant influence of the roadway on the control of the surrounding rock also indicated effective control of the surrounding rock’s deformation along the 1409 goaf. The support control technology system can provide specific reference values for roadways under similar geological production conditions.

Collaborative optimization of driving support technology in the W3233 working face return airway

Deep-shaft mining in roadway stress concentration, difficult control of the surrounding rock, and mining imbalance affect mining efficiency in coal mines. The mechanical parameters and crack development law of roadway surrounding rock were studied by laboratory experiments. The mechanical model was established by the method of theoretical analysis, the maximum empty roof distance was deduced, and two support schemes were designed. Through the numerical simulation method, the support scheme was compared and analyzed, the deformation rule of roadway surrounding rock, the optimization of roadway support parameters and the application of hysteresis technology are studied. The effect of different support schemes was verified by three-dimensional similar simulation experiments. The practical engineering verification showed that the construction time of each support circle was reduced by approximately 1 h, and the work was completed 60 days earlier. The research showed that the optimal support scheme was support scheme 1 (7 bolts with 800 mm × 1000 mm spacing between the roof, 10 bolts with 800 mm × 1000 mm spacing between the two sides, and 2 × 1 × 2 cables with 1600 mm × 2000 mm spacing between the roof). Support scheme 1 was applied to the engineering site to control the deformation of surrounding rock at 80 mm, and the deformation was less than the original support scheme. The construction was completed in advance under the hysteresis process, and the support efficiency and operation safety were improved. The results revealed the mechanism of surrounding rock control and proved the effectiveness of digging support synergy. This optimization plan serves as a reference for studying roadway support in rapid excavation and provides theoretical support for safe and efficient coal roadway mining.

An efficient HLL-based scheme for capturing contact-discontinuity in scalar transport by shallow water flow

An efficient numerical scheme is developed for coupled hydrodynamic and scalar transport systems to guarantee the conservation and the positivity-preserving properties for water depth and scalar concentration. A second-order well-balanced positivity-preserving central-upwind scheme based on the finite volume method is adopted to discretize both the Saint-Venant system and the advective fluxes in the scalar transport system. In particular, an anti-diffusion modification is augmented in an ad hoc manner to the Harten–Lax–van Leer approximate Riemann solver for the scalar transport system, with the aim of significantly reducing the numerical diffusion near contact discontinuities. The proposed scheme is validated through seven numerical experiments, wherein the advection and diffusion processes of scalar transport are considered either separately or in combination. Accuracy is measured based on the difference between the numerical results and analytical solutions, and the performance of the proposed scheme is assessed by comparing it with that of the existing scheme. Convergence analysis confirms that the proposed scheme is accurate to the second order. The stationary steady state with wet-dry fronts is simulated, which verifies that the proposed scheme can preserve the exact C-property. The results for the pure diffusion case reveal that the original scheme has limitations in precisely predicting scalar diffusion when the diffusion coefficient is small. By contrast, the proposed scheme accurately approximates scalar diffusion, even at low diffusivity. The results under flow conditions with various Froude and Péclet numbers confirm that the proposed scheme is more accurate than the existing scheme in solving scalar transport problems over a wide range of shallow water flows.

A Large Time Step Wave-Adding Simple Scheme for Unsteady Compressible Flows

In this paper, we construct a large time step wave-adding scheme (LTS-WA) for unsteady Euler equations in compressible flows with a much simpler strategy in the wave-adding procedure, named LTS-WAS. The new method does not need to calculate coefficients of contribution and also add the waves according to their types and families, which makes the scheme easy for coding and optimisation. The new scheme has a high speedup ratio, and its formulation is the same in scalar and system cases. The scheme is extended to 3D compressible flows using the dimension split method. Numerical experiments show that the new scheme maintains the advantages of the original LTS-WA scheme at large CFL numbers, and has a higher efficiency.

Classifying patients with non-specific chronic low back pain using the impact stratification score in an online convenience sample

BackgroundIn 2014, the National Institute of Health Pain Consortium’s research task force (RTF) on research standards for chronic low back pain (CLBP) proposed the Impact Stratification Score (ISS) as a patient-reported outcome measure that could stratify patients by the impact CLBP has on their lives. This work compares three newly developed ISS-based classifications to the RTF’s original to provide an optimal recommendation.MethodsThe online sample included 1226 individuals from Amazon’s Mechanical Turk who indicated having non-specific CLBP, average age of 40, 49% female, and 67% White. Participants completed the PROMIS-29 v2.1 profile survey that contains the 9 ISS items as well the Roland-Morris Disability Questionnaire (RMDQ) and Graded Chronic Pain Scale (GCPS). Other items included high-impact chronic pain; not working due to health problems; overall health; and number of healthcare visits for back pain in the past 6 months. Three new classifications were created using quartiles (Classification 2), latent profile analysis (Classification 3), and one modeled after the GCPS (Classification 4). Classifications were subsequently compared to the RTF-proposed classification (Classification 1) on several concurrent and prognostic criteria.ResultsClassification 1 had three CLBP severity groups, four in Classification 2, three in Classification 3, and four in Classification 4. All novel classifications improved upon the original. Classification 2 performed best at minimizing the classification of those with negative outcomes into the lowest severity groups at baseline (e.g., 11% with RMDQ ≥ 7) and 6 months (e.g., 8.2% had fair/poor health). Classification 4 performed best at maximizing classification of those with negative outcomes into the most severe group concurrently (e.g., 100% had GCPS grade ≥ 2) and at 6 months (e.g., 100% with RMDQ ≥ 7).ConclusionsWe developed three ISS-based classification schemes and tested them against several outcomes. All three improved upon the original scheme. While appearing more optimal than other classifications in the lowest severity groups, Classification 2 presents some considerations and limitations. Given that Classification 4 was an improvement at the lowest end of severity and was the best at the highest end, it is our tentative recommendation that this approach be adopted to classify individuals with non-specific CLBP.

Syuzevskoye diamond placer: A new stage in studying the diamond potential of Western Urals

Research subject. Geological features of the structure and composition of the Syuzevskoye diamond placer in the Aleksandrovsky region of the Perm Krai. The placer was found in the border zone of two regional tectonic structures of the Urals: the Western Ural outer folding zone and the Central Ural uplift. This placer was developed within the erosion-karst (?), erosion-structural or tectonically determined Chikman-Nyarskaya depression. Materials and methods. The placer was identified in the period from 2017 to 2022 during a geological study of the subsoil area “Glubokiy” (License PEM 02687 KP LLC “Almining”). Mining and enrichment works were carried out according to the original enrichment scheme using the clamshell sampling method, heavy media and electromagnetic separation. The morphometric characteristics of several hundred diamonds were identified and described; reports were prepared; and reserves were assessed. Results. In the section of the Syuzevskoye placer, two diamond-bearing strata are clearly distinguished, separated by poor- and non-diamond-bearing deposits; anomalously high seam thickness for the Ural placers (up to 14-16 m) was established; high areal productivity of the placer (up to 0.7-1.2 ct/m2) and high diamond content (up to 0.5 ct/m3 per sample and an average of 0.09 ct/m3 for the placer). The placer is attributed to the type of placers of tectonic scarp zones. Reserves of alluvial diamonds weighing 430.5 thousand ct of the Syuzevskoye deposit are estimated at C1 + C2 categories in the area limited by the area between exploration lines 107-116 (size 1000 x 750 m); approved by the Minutes of the GKZ Rosnedra No. 7139 dated November 18, 2022 and will be increased. Certificate No. PEM 23 DRK 10147 confirming the discovery of a mineral deposit, issued by the Federal Agency for Subsoil Use of the Russian Federation to LLC Almining on March 29, 2023. Over 90% of diamonds are of gem quality. The average mass of crystals in the reserve calculation loop is 87 mg, and behind the loops is 29 mg. The leading size classes by mass -8 + 4 and -4 + 2 mm are 93.9% and 72.3% in quantity with an average mass of a diamond crystal of 99.9 mg. The shape is dominated by dodecahedroids (66.9%), less fragments of crystals with an unpreserved shape (14.9%) and fragments of crystals (13.1%); octahedrons (2.4%) and tetrahedroids (2.2%) are rare, rhombic dodecahedroids (0.4%) are rare. The preservation of crystals is good: full crystals make up 63.7%, fragments of crystals - 16.3%, fragments - 12.9%. Most of the crystals do not have wear (42.4%), or have weak wear of the tops and ribs (43.0%), medium and strong wear was noted only in 13.7% of the crystals. The average cost of diamonds is estimated at 361.59 USD per 1 ct. Conclusions. A unique deep-seated diamond deposit has been discovered, which is considered as a new type of deep-seated diamond-bearing placers in tectonic ledge zones. The geological criteria for identifying such diamond deposits in the Urals were determined. A new technological scheme for prospecting and exploration of deep-seated diamond placers within erosion-karst and tectonically determined depressions was developed, which is applicable for prospecting for precious metal placers.

Sliding-mode observer-based fault diagnosis and fault-tolerant control of the main drive system of rolling mill

In order to address the problem that the main drive system of rolling mill is easily affected by the impact of biting steel, and considering the nonlinear friction damping and the external perturbations of the main drive system of rolling mill during the rolling process, a fault model of the main drive system of rolling mill is established, and a fault diagnosis and fault tolerance control method of the main drive system of rolling mill based on the nonlinear sliding-mode observer is proposed. In order to suppress the influence of external perturbations on fault diagnosis, a nonlinear sliding-mode observer is constructed for fault diagnosis and fault reconfiguration of the system, and the robustness of the observer to fault reconfiguration is improved by using the sliding-mode control rate [Formula: see text], and the stability of the designed nonlinear sliding-mode observer is proved using Lyapunov’s stability theorem. In order to ensure that the system can operate normally even after a fault occurs, a reference model is designed, and a new controller is redesigned for fault-tolerant control of the system by adding a fault compensation term to the original control scheme using fault estimation information. Through the simulation study of the main drive system of stand F4 of 2030 mm cold rolling mill, it is verified that the observer can accurately track the system state with an angular velocity error of 2.45% and detect and estimate the main drive system failure of rolling mill with an estimation error of no more than 0.04% after a fault occurs; the fault-tolerant control of the main drive system of rolling mill is carried out by using the fault information to restore the system to its normal state, and the angular velocity error is 1.89%.

A genetic algorithm-based approach for flexible job shop rescheduling problem with machine failure interference

Rescheduling is the guarantee to maintain the reliable operation of production system process. In production system, the original scheduling scheme cannot be carried out when machine breaks down. It is necessary to transfer the production tasks in the failure cycle and replan the production path to ensure that the production tasks are completed on time and maintain the stability of production system. To address this issue, in this paper, we studied the event-driven rescheduling policy in dynamic environment, and established the usage rules of right-shift rescheduling and complete rescheduling based on the type of interference events. And then, we proposed the rescheduling decision method based on genetic algorithm for solving flexible job shop scheduling problem with machine fault inter-ference. In addition, we extended the "mk" series of instances by introducing the machine fault interference information. The solution data show that the complete rescheduling method can respond effectively to the rescheduling of flexible job shop scheduling problem with machine failure interference.