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Early tied-arch bridges cannot satisfy the current traffic load demand due to their load grades and maintenance levels. Also, these tied-arch bridges have accumulated structural damage with increasingly prominent safety risks. In order to accurately evaluate the characteristics of tied-arch bridges' structural-influenced lines and identify damage of their arch ribs and suspenders, two analytical solutions are derived and established in this paper for the thrust-influenced lines of parabola and catenary two-hinged arches with a tie beam. A new method and an index for identifying damage of arch ribs and suspenders of tied-arch bridges are proposed. The results of numerical simulation in this paper verified that the proposed analytical solution has good analytical accuracy in practice on those two-hinged nonflat arches. With the use of equivalent thrust-influenced line difference curvature, the effectiveness of damage identification and the verification method were verified on the tie beam, suspender, and arch rib of plane tie arch structure as well as the suspender and arch rib of tied-arch bridges in this research. Furthermore, combining with grey relation analysis, the noise immunity of the proposed index method can be verified. Also, thrust-influenced line recognition based on VMD (variational mode decomposition) is introduced, and a practical process of bridge health assessment based on the quasistatic-influenced line loading of three-axle heavy vehicles is established. Theoretical analysis and numerical verification show that the calculated error of the analytic solution of two-hinged arches with a rise-span ratio greater than 1/8 is less than 9.57%, and the error decreases with the increase of the rise-span ratio. Therefore, it can be applied to the calculation and analysis of tied-arch bridges with a rise-span ratio range between 1/4 and 1/5. With the equivalent thrust-influenced line index proposed in this paper, the damage of suspenders and arch ribs of tied-arch bridges can be accurately located. It has been found that the proposed method is more effective to identify the damage of suspenders than the damage of arch ribs does, showing good noise immunity. In summary, this research has provided theoretical support for arch bridge design and evaluation. Combining with existing bridge-monitoring methods, the new bridge damage identification method proposed in this paper has the prospect of realizing the normal health status assessment of existing tied-arch bridges. [ABSTRACT FROM AUTHOR]

In this study, a heterojunction (P+ a-SiC/i intrinsic/n-Si) solar cell has been examined and characterized using the Analysis of Microelectronics and Photonic Structures (AMPS-1D) simulator. In this heterojunction solar cell, an intrinsic layer is imposed to enhance the efficiency and performance. The optimum efficiency of 36.52% (Voc = 1.714 V, Jsc = 27.006 mA/cm2, and FF = 0.789) has been achieved with this intrinsic layer. It has also been observed the solar cell without intrinsic layer. In this case, the maximum efficiency of 2.378% has been observed which is very poor. The heterojunction solar cell also has been investigated with electron blocking layer (EBL) and defect layer. In this case, the simulation result shows the lower efficiency (34.357%) than the previous. This research paper introduces an optimized model of a heterojunction solar cell enhanced with an intrinsic layer to improve efficiency. The proposed design shows significant promise in its theoretical framework. Looking forward, the design could be realized in laboratory settings and has the potential to be scaled up for broader applications. [ABSTRACT FROM AUTHOR]

Considering that the effect of solar radiation on the super-high arch dam temperature field remains poorly studied, the calculation accuracy of dam temperature deformation is unable to be guaranteed accordingly. To address the issue, the solar radiation effect is adequately taken into consideration by proposing a practical calculation method based on the ray-tracing algorithm, the precomputation algorithm, and the ASHRAE clear sky model in this paper. With the aid of the ASHRAE clear sky model, the solar radiation received by the super-high arch dam and reservoir water is calculated. The shading effects are calculated by means of the ray-tracing algorithm, and the precomputation technology is introduced to further enhance the computational efficiency. Finally, to guarantee the authenticity of the calculation results, the dam thermodynamic parameters are inversed by employing the hybrid genetic algorithm. Based on the application in a real-life case, we concluded that around one third of the entire dam radial temperature deformation was attributable to solar radiation during continuous sunny days. The analysis results signify a critical role for taking account of the solar radiation in dam deformation calculation. Furthermore, the practicability and utilization prospect of the proposed method was verified. [ABSTRACT FROM AUTHOR]

The search for efficient higher order methods is a constant goal in numerical analysis. In this paper, a higher order two-step hybrid block method is presented to directly solve second-order initial value problems in ordinary differential equations. In addition to the higher order, the proposed method has been formulated in variable step-size mode to extract its best performance. Comparisons with other methods in the literature show the good accuracy it can provide. Theoretical aspects such as linear stability and convergence analysis are also discussed. [ABSTRACT FROM AUTHOR]

This paper combines the digital twin system modeling method to conduct an in-depth study and analysis of graph-theoretic combinatorial optimization. This paper provides new ideas and approaches for optimal numerical analysis work by studying the digital twin modeling method that integrates digital modeling and graph theory combination, provides theoretical support for safe, stable, and economic operation of the system, proposes a solution for digital twin model based on big data platform, focuses on the nearest neighbor propagation (AP) and graph theory combination, solves the digital twin real-time monitoring data asynchronous, incomplete problem, and applies the algorithm to the digital twin model based on the big data platform for data preprocessing to achieve better results. This paper also presents a web-based digital twin system based on intelligent practical needs, analysis, and comparison of existing models, combined with digital twin technology, detailing the differences and connections between the various levels of numerical analysis and the implementation of this data in various fields, such as user management, equipment health management, product quality management, and workshop 3D navigation and detailed modeling of the digital twin system based on this numerical analysis to realize remote online monitoring, analysis, and management. In this paper, for the numerical analysis process, firstly, the key technologies of modeling and simulation operation control of production line based on digital twin are studied, and the rapid response manufacturing system based on a digital twin is designed and validated. Secondly, a scheduling technology framework for capacity simulation evaluation and optimization is established, and batching optimization, outsourcing decision, and rolling scheduling techniques are thus proposed to form a batching optimization algorithm based on priority rules, which realizes batching processing, outsourcing decision, and rolling scheduling of production orders to optimize equipment utilization and capacity. Finally, digital twin-based modeling is designed, and the validation results demonstrate the system's superior performance in achieving information interaction between physical and virtual production lines, optimization of numerical analysis, and display of results. [ABSTRACT FROM AUTHOR]

This paper studies the complexity analysis in production between competition and R&D for a traditional energy vehicles enterprise and a new energy vehicles enterprise under the introduction of corporate average fuel consumption credits and new energy vehicle credits mandate. From the internal perspective of market complexity evolution, this paper analyzes the internal mechanism of market competition fluctuation and discusses the influence of different corresponding speeds of enterprises on market stability through the nonlinear dynamics' theory. The research results show that the adjustment coefficient of R&D investment and the price coefficient of credit transactions are the key factors affecting the competitive strategies of the two companies. The difference between these two factors will even change the relative R&D investment intensity, relative profitability, and market stability of the two companies in a balanced state. In addition, the numerical analysis showed that the time-delay feedback control method could control the unstable behavior of the dynamic system efficiently and quickly and make the market quickly recover a stable and orderly state, which provided a scientific basis for decision makers to effectively solve the market instability. [ABSTRACT FROM AUTHOR]

The willingness to improve the security and reliability of power supply to end-users, often pushed by prescriptions of national regulatory authorities, is bringing considerable challenges for distribution system operators. Islanding a portion of the public distribution network after a fault is considered a measure to mitigate the effects of service interruptions. This procedure is usually carried out by counterfeeding the grid through a generator set (GenSet). Even if this approach is widely adopted around the world, reenergizing the grid and keeping the electric island stable is not a trivial task. In this framework, the scope of this paper is to provide a set of technical guidelines for the usage of GenSets to supply public grids in emergency conditions. The goal is to highlight the static and dynamic limits of the GenSet operations and simplify their exploitation for the grid operators. The numerical analyses, which have been carried out through the RMS simulation tool of the DigSilent PowerFactory software, also aim to evaluate the technical constraints in the case of active networks, which involve distributed generation implementing regulations according to ENTSO-E and Italian technical standards. [ABSTRACT FROM AUTHOR]

The development of geographically indicative (GI) agricultural products can effectively promote the development of local rural residents' per capita net income (PCNI) and the gross output value of agriculture, forestry, animal husbandry, and fishery (GOV-AFAHF). This paper takes agricultural products with geographical indications in Anhui Province as the object of study and uses numerical analysis to analyze their application, geographical distribution, and various distribution in detail. By comparing it with the central region, this paper conducts an empirical study on its impact on agricultural economic development, analyzes its related variables and data, draws its effect on farmers' PCNI, and on this basis puts forward some countermeasures. In order to make the agricultural products with GI in Anhui Province develop better, according to the results of comparative analysis and empirical analysis, it puts forward suggestions for regulating the development of management industry associations, implementing the regional branding strategy of GI agricultural products, and increasing the construction of rural infrastructure. In addition, the experiment shows that under the condition of controlling other influencing factors unchanged, for every 1% increase in GI agricultural products, the average increase of PCNI of rural residents is 0.08%, which further confirms the conclusion that GI agricultural products can promote the development of GOV-AFAHF. [ABSTRACT FROM AUTHOR]

The topology optimization design invariably shall be used in various applications such as four bar mechanisms, robotics designs, aircraft engineering designs, and many other mechanical innovative systems for improving the efficiency in the system. This research paper emphasizes more on general topology optimization design for a rectangular domain in which numerically analyzed with defined boundary conditions. Furthermore, the same setting geometry has been taken for sensitivity analysis to find the objective stress and nonstress zones. Then, the geometry is topology optimized to analyze stress, safety factor, output deflection, and mass reduction. Also this research work focuses more on topology optimization, design synthesis, and objective function comparison in different materials. Hence, the results are suitable volume and mass reduction in various robotic devices. Validation and comparison of compliance base materials will further support the paper to extend the work for experimental analysis. This final topology optimized and validated device can be manufactured and forced to experimental fatigue endurance test cycle test condition in static and dynamic state. The results outshoot the final destination of this optimization design. [ABSTRACT FROM AUTHOR]

The introduction of hierarchical structures into conventional honeycomb structure materials can increase the mechanical properties of honeycomb materials. This paper studies the in-plane collapse response of a new second-order diamond-shaped hierarchical honeycomb (DHH) (the cell walls are composed of equilateral triangles) and systematically studies the quasi-static collapse response and dynamic collapse response of the DHH in two directions through the finite element method. The quasi-static collapse response of the DHH is analyzed by a two-scale research method, and combined with momentum conservation law, the study is extended to dynamic collapse response. This paper also studies the collapse response of the DHH with different number of substructures, different relative densities, and different impact speeds, and the results are verified by theoretical analysis and numerical simulation. The results show that adding hierarchical structure can greatly increase the collapse stress of the diamond honeycomb structure and make the structure have better energy absorption effect. [ABSTRACT FROM AUTHOR]

SiC fiber-reinforced silicon matrix (SiCf/SiC) composites are of significant interest for the aircraft engine. The thermal conductive behaviors of [0-90-0]s SiCf/SiC composites along in-plane and out-of-plane (thickness) directions were reported in this paper. The thermal conductivity of the SiCf/SiC composite was tested by using the steady-state measuring apparatus. Then, the thermal conductivity of the SiC matrix was predicted by finite element analysis (FEA). The representative volume element (RVE) models of SiCf/SiC composites were built, and FEA was used to investigate thermal conductive behaviors. It was found that the thermal conductivity along the fiber radial direction was greater than it was in the axial direction in the SiCf/SiC composite and that the thermal conductivity of the out-of-plane direction is lower than that of the in-plane one. The thermal conductivity of the SiCf/SiC composite in the in-plane direction at room temperature was 31.1 Wm−1K−1 and 28.5 Wm−1K−1, and the thermal conductivity in the thickness direction was 24.9 Wm−1K−1. The experimental thermal conductivity showed a good agreement with the thermal conductivity of FEA. [ABSTRACT FROM AUTHOR]

The squeezed multiple-branch pile is a variable section pile that was built by adding a bearing branch cavity to a constant section pile using expansion and extrusion equipment. It is widely used in engineering practice for its high bearing capacity, small settlement deformation, high economic benefits, strong adaptability, and simple pile forming process. In this paper, a new type of squeezed multiple-branch pile is proposed and its forming tool is invented. The forming tool of the pile has applied for an invention patent and is authorized by the China National Intellectual Property Administration. Multiple groups of comparison models of the new squeezed multiple-branch piles are established by using FLAC3D numerical simulation software to investigate the influence of the number and spacing of branches on the bearing mechanism in response to uplift load. The results indicated that the number and spacing of branches have a significant effect on the uplift bearing capacity, load–displacement curves, side friction resistance, and stress distribution law in the new pile and soil around the pile. The suitable number and spacing of branches maximize the uplift bearing capacity and minimize the settlement of a single pile. [ABSTRACT FROM AUTHOR]

The temperature is a critical factor that determines the unfrozen water content and ice content in the frozen soil. In view of mechanical properties of the frozen soil depend on the volume of components of the four-phase systems, thus the temperature has a significant impact on the mechanical behaviors and deformation properties. The thermal state of the embankment in permafrost regions has a significant seasonal difference, then the seismic performance of the embankment alters with the season. In addition, the seismic performance is highly influenced by the properties of the earthquake motion, especially the seismic intensity. Combining these factors, a numerical simulation was conducted in this study. In this study, taking a typical section of Qinghai-Tibet Railway as an example, a numerical case study on the seismic behavior of embankment was carried out using the dynamic explicit FEM code ABAQUS/Explicit. The El Centro excitation with different intensities was performed in numerical analysis and two distinct thermal states of the embankment in extreme cold and warm days were considered as well. The seismic behaviors of the embankment, including the acceleration responses, the strain response, and the displacement response, were studied effectively. This paper proposes approaches and methods to study the seismic failure mechanism of the infrastructures, and the results can serve as a scientific basis for resisting earthquakes and preventing disasters in cold regions. [ABSTRACT FROM AUTHOR]

As the composite pile, the precast concrete piles reinforced with cement-treated soil (PCCS) is formed by driving the precast cement (PC) pile into the deep mixing (DM) column, which has been successfully and widely utilized to support buildings and embankments over soft soil. To increase the pile spacing and give full play to the economic merits of the PCCS, a reinforcement scheme, which involves the combined use of rigid piles and flexible columns, employing penetrated PCCSs and floating DM columns is proposed and utilized for soft soil ground treatment. However, there is a lack of feasible method for consolidation behaviors of this combined composite foundation (CCF) reinforced with penetrated PCCSs and floating DM columns under flexible loads. This paper developed an analytical solution to predict the average consolidation degree of this CCF based on a cylinder consolidation model and double-layer ground consolidation theory. The excess pore pressure and average consolidation degree were calculated by considering the composite pile penetration into the cushion. The analytical method agrees well with results obtained by numerical analysis. Additionally, a parametric study was conducted systematically to analyze the effect of key influence factors on the average consolidation degree of this CCF. The results indicate that the consolidation rate of this CCF can be much faster than that of the natural ground. The consolidation rate strongly depends on the compressive modulus and area replacement ratio of PCCSs. The increasing inner core-outer core modulus ratio and the inner core-subsoil modulus ratio increase the consolidation rate of this CCF. In addition, the consolidation rate increases with the gravel cushion-subsoil modulus ratio, while it decreases with the loading period. [ABSTRACT FROM AUTHOR]

In this paper, we use digital twin technology to conduct in-depth analysis and research on the modeling of complex systems for smart aging. The solution of the digital twin model based on a big data platform is proposed, and the problem of asynchronous and incomplete digital twin real-time monitoring data is solved, and the algorithm is applied to the digital twin model based on the big data platform for data preprocessing to achieve better results. To improve the real-time data transmission, the OPCUA information modeling method is optimized by using node merging and adaptive compression, which statutes the system data and achieves the effect of information fusion. The Web protocol is also used to unify the digital twin information interaction form. After experimental testing, the effectiveness of the information modeling scheme designed in this paper is verified. The fall detection results based on the digital twin selected thresholds are significantly better than the experimental results of the manually set threshold method; the thresholds set by the digital twin can more accurately identify daily behaviors, especially the more violent daily behaviors such as lying down, and the accurate alarm rate of the falling behavior reaches 92.5%. In contrast, the artificially set thresholds have a lower overall recognition rate for human behaviors and are prone to misclassification, with a misclassification rate of 3.8%. Therefore, it can be determined that using the digital twin method to set feature thresholds is better than the manual setting threshold method in terms of detection accuracy, and the digital twin method is chosen to select the thresholds for each stage of the fall process in this project. The validation results demonstrate the system's excellence in information interaction, optimization of numerical analysis, and display of results for smart aging. [ABSTRACT FROM AUTHOR]

Because thermowells are prone to fatigue damage in petroleum cracking gas pipelines, in this paper, the LES method is used to simulate the flow around thermowells through two-way thermal-fluid-solid coupling, the internal causes of thermowell damage are explored, and measures for improving the thermowell safety are proposed. According to this study, when high-speed, high-temperature gas passes the thermocouple bushing, the main factors affecting the structural safety of the thermocouple bushing are the alternating stress caused by the vortex falling off, the thermal stress cycle due to the temperature gradient, and the pressure gradient impacted by the gas. Furthermore, this paper proposes improving the thermowell safety by installing the interference devices and optimizing the installation angle. The improvement measures were studied by conducting a two-way thermal fluid-structure coupling simulation. The results of this study show that after installing the interference device and optimizing the installation angle the displacement deformation of the thermowell and the equivalent stress is reduced by 57.2% and 72.1%, respectively, which indicates the safety improvement of the thermowell structure and the effectiveness of the method. The research contents of this paper can provide guidance for the installation and use of thermocouple bushing. [ABSTRACT FROM AUTHOR]

In Dempster–Shafer evidence theory (DST), some classical evidence combination rules can be used to fuse the multiple pieces of evidence, respectively abstracted from different attributes (features) so as to increase the accuracy of multiattribute classification decision making. However, most of them have not yet considered the interdependence among multiple pieces of evidence. The newly proposed maximum likelihood evidential reasoning (MAKER) rule measures such ubiquitous interdependence by introducing correlation factors into evidence combination. Hence, this paper designs a MAKER-based classifier to mine more correlation information for data classification. Finally, some numerical analysis (classification) experiments are carried out using five popular benchmark databases from the University of California, Irvine (UCI) to illustrate that the refined measure for evidence interdependence can aggregate the fused probability (belief degree) into real class label of a sample and further improve classification accuracy. [ABSTRACT FROM AUTHOR]

The development of underground space is fast because of the lack of space. To build shafts in underwater tunnels, the vertical tunneling method (VTM) was invented in 1974 in China, which can act as a freshwater intake or sewage outlet. During the operation of the VTM, the jacking force is one of the essential factors that draw attention. This paper conducts a numerical study of the jacking force and its influencing factors during the vertical tunneling process. First, based on the finite element software ABAQUS, a numerical model of the vertical tunneling process is established according to the VTM project in Beihai, China. Second, in accordance with the Latin hypercube sampling method and the multivariate significance analysis, the mechanical parameters are determined or back-analyzed. Then, the calculated jacking force of the numerical model is compared with the measured jacking force. It turns out that the changing trend of the jacking force in the numerical model and the measured jacking force is relatively consistent. Finally, the influencing factors of the jacking force, such as elastic modulus and the angle of internal friction, are analyzed based on the numerical model. The results show that the elastic modulus and the angle of internal friction of soil are the main influencing factors of the jacking force. The secondary factors are Poisson's ratio, static earth pressure coefficient, unit weight, and cohesion. [ABSTRACT FROM AUTHOR]

Compared with a conventional turbine, counter rotating turbine has larger thrust weight ratio, shorter axial distance, and higher efficiency. It has been widely used in high-performance aviation. In conventional counter-rotating turbine, HPT is located in the front of LPT, and only a stator row can be eliminated. The layout limits the turbine weight and efficiency. Therefore, the staggered counter rotating turbine is proposed, and the staggered counter rotating turbine can eliminate the all-internal stators, which can greatly improve the turbine weight and efficiency. The staggered counter rotating turbine is the development and improvement of counter rotating turbine. Due to the elimination of the all-internal stators, the downstream rotor will suffer from the insufficient inlet swirl, which is the main question in staggered counter rotating turbine design. Furthermore, the turbine outlet angle is also an important parameter to evaluate the turbine design. The coordination of inlet swirl and outlet Mach number and the outlet angle is discussed by the theoretical method. In order to verify the design method, two-dimensional throughflow design, blade design, and three-dimensional numerical analysis are performed. Expansion ratios and efficiency at the speed combinations of the 80% to 105% are discussed to reveal the turbine characteristics at off-design conditions. An adiabatic total-to-total efficiency of 92.1% with expansion ratio of 4.47 at design point is obtained and achieves the initial design goal very well. The paper is aimed at providing a technical approach to improve the thrust weight ratio, efficiency of high bypass turbofan engines, and provide new ideas for the development of aeroengines. [ABSTRACT FROM AUTHOR]

To provide decision support to the commander, it is necessary to calculate shipborne vehicles' sortie mission reliability during the formulation of the layout plan. Therefore, this paper presents the sortie mission network model and reliability calculation method for shipborne vehicles. Firstly, the shipborne vehicle layout and sortie task characteristics are used to establish the sortie mission network model. The shipborne vehicles' sortie mission reliability problem is transformed into a two-terminal network reliability problem. Secondly, the minimal path set method is used to calculate the two-terminal network reliability. An improved tabu search algorithm based on a strategy of breaking up the whole into parts is proposed to search for the minimal path set that matches the length. Finally, the sum of disjoint products is used to process the minimal path set to obtain the shipborne vehicles' sortie mission reliability calculation formula. A numerical analysis of two simplified shipborne vehicles' layouts is given to illustrate the calculation process of the method. This study provides a new evaluation index and an effective quantitative basis for the evaluation system of shipborne vehicles' layout. It also provides theoretical support for the development of decision-making related to the sortie mission of shipborne vehicles. [ABSTRACT FROM AUTHOR]

Summary: The paper considers errors that occur during strain measurement by fiber‐optic sensors based on Bragg gratings, which are mounted on the surface of the controlled object with a connecting material. Errors due to the use of the assumption of a uniaxial stress state in the Bragg grating zone in the strains calculation based on the measured physical quantities are considered. The errors associated with the strain gradient along the Bragg grating and the strain gradient from the measurement zone to the measuring element are analyzed. To answer the question of what strain is measured, the change in the measured strain as a result of mounting the sensor on the material surface is estimated. Models and algorithms for numerical simulation of errors arising in the strain measurement are presented. Numerical results are given for estimating the considered types of errors when sensor is mounted with epoxy adhesives on the surface of isotropic and anisotropic (fiberglass, carbon fiber) materials. Variants of experiments are presented in which various options of nonuniform distribution of strains and a complex stress state are provided in the zones of strain measurement. The experimental results are compared with the results of numerical simulation based on the finite element method. The results of the analysis of the choice of the resonant wavelength from the reflected optical spectrum, which is used to calculate the strains under the assumption of a uniaxial stress state in the Bragg grating, are presented. [ABSTRACT FROM AUTHOR]

The study of landslide dynamic characteristics and accumulation patterns is of great significance for the quantitative evaluation of landslide hazards. This paper takes the Tangjiashan landslide as a research case, a real 3D model was established based on high precision DEM data to determinate the terrain characteristics and pre- and postlandslide image data to determinate the shape and size of the sliding body. Particle flow 3D program (PFC3D) is carried out to reappear the complete movement of the Tangjiashan landslide. And the dynamic characteristic factors are monitored and analyzed such as the velocity and displacement of the landslide body. The result shows that the Tangjiashan landslide is a traction-type landslide, which lasts about 37 s in total and can be divided into four stages: destabilization and destruction, collapse and accelerated sliding, high-speed sliding, and deceleration and accumulation. The maximum sliding distance is about 642.05 m and the maximum sliding speed is about 38.67 m/s. This is a typical high-speed short-range landslide, and the speed of sliding body surface is much greater than that of other parts, which show an obvious characteristic of clastic flow. In the Tangjiashan landslide, the slip distance is the controlling factor in determining the speed of the landslide at different locations. [ABSTRACT FROM AUTHOR]

According to the needs generated by the industry, there is an urgent need to investigate the flow vibration response law of the elastic tube bundle of heat exchangers subjected to the coupling effect of shell and tube domain at different inlet flow velocities. In this paper, based on the continuity equation, momentum equation, turbulence model, and dynamic grid technology, the vibration response of the elastic tube bundle under the mutual induction of shell and tube fluids is studied by using pressure-velocity solver and two-way fluid-structure coupling (FSC) method. The results show that the monitoring points on the same connection block have the same vibration frequency, while the vibration amplitude is different. Monitoring point A is the most deformed by the impact of fluid in the shell and tube domain. When the inlet velocity( v shell = v tube = 0.15 , 0.4, 0.5 m/s) of shell and tube is low, the amplitude of tube bundle vibration in the Y direction is greater than that in X and Z direction, and the tube bundle produces periodic vibration in the vertical direction. The vibration equilibrium position of the tube bundle along the shell flow direction gradually moves up with the increase of the inlet velocity. The amplitude in the Y -direction of the elastic bundle decreases with the increase of shell-side and tube-side velocity. The relationship between the vibration amplitude in the Y direction and the entrance velocity is a linear function. [ABSTRACT FROM AUTHOR]

A ballastless track is susceptible to damage and even failure of structural components under the long-term effects of extremely high temperatures. In this paper, considering the influence of different constraint boundaries, a 1 : 4 scaled model of a ballastless track-bridge structural system was produced and placed in a large-sized environmental chamber. The thermal performance of the track structure was studied by carrying out temperature loading tests at extreme temperatures. In combination with the scaled-down model test data, a 3D nonlinear finite element model was established to investigate the damage evolution of broad-narrow joints under temperature gradient loading. The results are shown as follows: (1) the cement asphalt (CA) mortar layer has a hysteretic effect on the vertical temperature transfer. The most unfavorable structural part is between the track slab and the CA mortar layer of the track structure. (2) The constraint conditions accelerate the rate of temperature transfer, creating disturbances to the internal stresses of the track structure and amplifying the internal stresses induced by the environmental temperature increase. (3) Temperature and longitudinal stresses in the track's structural layers are highly correlated. There is a significant quadratic regression between internal temperature and structural stresses in different extreme high-temperature environments. (4) As the temperature gradient load increases, the damage occurs at the junction of the broad-narrow joint and tends to expand towards the ends, which has little effect on the compression damage of the broad-narrow joint but significantly increases the tension damage. The research could provide useful guidance for the scientific operation and maintenance of the ballastless track in extreme high-temperature environments. [ABSTRACT FROM AUTHOR]

The obvious anisotropy of layered rock mass prevents the built-in constitutive model of commercial simulation software from accurately describing the elastoplastic behavior of the rock mass. In this paper, a transversely isotropic elastoplastic constitutive model (called the AN-MC model) that characterizes the elastoplastic failure behavior of the layered rock mass is developed by introducing the Mohr-Coulomb yield criterion with the tension cutoff in the model based on the transversely isotropic constitutive model and deriving its finite difference scheme. The development and programming of the transversely isotropic elastoplastic constitutive model are achieved on the basis of the secondary development platform of FLAC3D and the VC++ environment. The accuracy and rationality of the proposed constitutive model are verified in terms of consistency of the calculation results of the developed transversely isotropic elastoplastic constitutive model and the built-in constitutive models. In the numerical analysis of the Queerxi tunnel project, the calculation results of the AN-MC model are in good agreement with the field monitoring data. Thus, the deformation characteristics of the tunnel surrounding rock are well characterized. Comparative analysis of the deformation and failure laws of the layered surrounding rock and isotropic surrounding rock indicates that the plastic failure range of the layered surrounding rock tunnel is larger, and the arch foot and waist are prone to plastic penetration failure with butterfly-shaped characteristics. The research results are important for the scientific prediction and precise support of layered rock mass deformation. [ABSTRACT FROM AUTHOR]

In recent years, there are many problems in the construction of street landscape spatial pattern, such as emphasizing the surface, ignoring the substance, focusing on construction, and ignoring protection. The reason is closely related to the lack of visual evaluation of streetscape for guidance. This research mainly discusses the numerical analysis and calculation for the spatial pattern of urban streetscape. This study clarifies the related concepts of visual evaluation of urban streetscape and discusses the formation process, overall characteristics, and constituent elements of streetscape. It emphasizes the importance of two subjective and objective factors of "landscape" and "vision" for evaluation. This paper studies this spatial composition relationship from the perspective of street space and the building itself. In the research process, it selects the pedestrian street in the northwest of the city as the object and uses the questionnaire survey method and the multifactor evaluation method to carry out the visual evaluation of the streetscape. It deeply discusses the application of evaluation methods in practice and counts the relevant evaluation results. In the urban street space proportion curve and the corresponding comparative analysis, it is found that most of the street space proportion is between 0.6 and 3.0. This kind of space composition has mutual inclusive symmetry, which enhances the order and communication of urban architecture. This somewhat improves this alienated spatial morphological pattern. This research is helpful to promote the development of streetscape visual evaluation. [ABSTRACT FROM AUTHOR]

This paper is devoted to the analysis and design of H∞ filtering for discrete-time Takagi–Sugeno (TS) fuzzy systems with time-varying delays. By using the delay-partitioning method, more systematic information is introduced, which can reduce the conservatism of the conclusion. By constructing an appropriate Lyapunov functional and combining with a newly Wirtinger-based summation inequality, the existence condition of the H∞ filter is obtained. Thus, utilizing the contract matrix transformation method, the H∞ filter design for discrete-time TS fuzzy systems with time-varying delay based on LMI is proposed. Finally, a few numerical analysis results are given to prove the effectiveness of the method. [ABSTRACT FROM AUTHOR]

English is a universal language in the world. It has become the consensus of society as a subject of education in primary and secondary schools and even universities. Therefore, how to improve English reading ability has also become a focus area of school education and students. The current research on English reading is mainly based on the sense of reading questions, reading patterns, answering skills, etc. and lacks the analysis of English reading corpus. In view of this, this paper used a self-built English reading corpus, adopts the feature extraction method, and combines the convolutional neural network (CNN) to build a model to carry out numerical analysis on the self-built English reading corpus, optimized the model, and compared and analyzed the results obtained. The optimal dropout rate and iteration times were obtained by updating experimental parameters. In order to make the experimental results more convincing, the W2V-SVM and W2V-CNN models that combine different feature extraction and classification methods are designed. Compared with the optimized CNN model, the accuracy rate, recall rate, and F1 value of the optimized CNN model were 89.81%, 92.39%, and 92.8%, respectively. The accuracy, recall, and F1 value of the W2V-SVM model are 81.31%, 82.09%, and 81.25%, respectively. The accuracy, recall, and F1 value of the W2V-CNN model are 85.24%, 84.98%, and 85.12%, respectively. It shows that the optimized CNN feature classification model has better feature classification effect on the self-built English reading corpus. The experimental results meet the expected value. [ABSTRACT FROM AUTHOR]

The thermal insulation effect of snow on the active layer thickness of permafrost cannot be ignored. Under the dual influence of snow cover and roadbed construction, this paper studies the influence of snow cover on the temperature field and permafrost upper limit under the permafrost roadbed in the alpine mountains. Through the application of PDE module in Comsol software, the hydrothermal coupling analysis of roadbed is carried out by means of numerical analysis. The results show that the permafrost degradation is accelerated by the snow on the subgrade surface, the temperature increases significantly, the thickness of the active layer increases, and the permafrost upper limit moves downward. With the increase of seasonal snow thickness, the permafrost temperature under the subgrade increases, the low-temperature permafrost under the subgrade has the risk of changing to high-temperature permafrost. The melting groove is formed under the subgrade on the right side, and with the increase of snow thickness, the area of the melting groove expands and develops towards the center of the subgrade. Permafrost upper limit on the left and right shoulder is lower than that on the right shoulder, and snow cover has a greater impact on permafrost upper limit on the right shoulder. [ABSTRACT FROM AUTHOR]

Aiming at the safety of tunnel operation, based on the investigation and statistical analysis of a large number of operating tunnel diseases, comprehensively considering the interaction between the surrounding rock and the structure, this paper establishes the failure criteria for surrounding rocks and lining materials by using numerical limit analysis and theoretical analysis methods, analyzes the overall stability and instability failure mechanism on the shallow tunnel under unsymmetrical pressure during the operation period by using the strength reduction method in light of the operation safety of the tunnel, proposes the reasonable monitoring strategy, and also constructs monitoring index system. The analysis and research results show that the tunnel structure is affected by bias pressure due to the asymmetry of the terrain. The probability of disease in the bias pressure tunnel under asymmetric terrain conditions is significantly higher than that of the general terrain. The shallow tunnel under unsymmetrical pressure has experienced three development stages from shear failure to overall instability, including rock mass fracture and sliding, structural damage, and overall instability, which can be divided into eight processes. During operation, the key monitoring indicators of surface deformation are the subsidence and deformation of the slope top and the horizontal displacement of the slope itself, followed by the monitoring of the uplift and deformation at the bottom of the slope. Meanwhile, close attention should be paid to the structural stress states in the sliding direction and perpendicular to the sliding direction of the lining structure, which demonstrates that the principal compressive stress in the sliding direction is more sensitive than the principal tensile stress in perpendicular to the sliding direction and should be listed as the key monitoring and early warning indicators of the structural stress. [ABSTRACT FROM AUTHOR]

Precast technology is increasingly favoured by bridge engineers, and the seismic performance of precast bridge piers urgently needs to be addressed. Precast piers have a complex load-bearing mechanism, and their design method has not been clearly determined. Fibre plastic hinge theory can satisfactorily analyse the seismic performance of precast piers. In this study, the seismic performance of precast piers is analysed through numerical simulation of pier columns based on the pseudostatic testing of a set of existing precast piers and combined with fibre plastic hinge theory. The results show the following: With reasonable constructional measures, precast piers connected by grouted sleeves indeed have seismic performance similar to that of cast-in-place components. Finite-element programs can be employed to simulate the mechanical properties of steel rebars before yielding well but not those after yielding or under fatigue. When fibre plastic hinges are used for finite-element analysis, if the fibre cross-section is reasonably divided, the length of the plastic hinge has little influence on the results; otherwise, too densely distributed plastic hinges may lead to nonconvergence of the results in a later working condition. The plastic hinge method recommended in this paper, especially the sectional fibre-cross-section division method, can obtain the plastic hinge performance state, it can help save the test cost and make up for the shortage of test data. [ABSTRACT FROM AUTHOR]

The positioning accuracy is a key index to measure the performance of the robot. This paper studies the positioning accuracy of the main pouring mechanism of the hybrid truss pouring robot and analyzes that the main error sources affecting the positioning accuracy are machining error, assembly error, and thermal deformation error. Error transfer matrix is constructed to describe the influence of machining errors and assembly errors on the position and pose of the terminal, and the error parameters have physical significance. The probability distribution of sensitive errors is discussed. A joint regression prediction model based on sensitive error sets is established to determine the thermal deformation error on the basis of fully considering the contribution rate of component error. The results show that the position error has a wide range of influences on the end pose, but the angle error is more sensitive, and the probability distribution of the sensitive error is concentrated. The reliable data can be obtained without reorganizing the measurement in the calibration process. The joint regression model considering the contribution rate of component error can effectively eliminate the collinearity problem in the prediction of thermal deformation from a single heat source. Compared with the single regression model, it has better prediction accuracy and effect. [ABSTRACT FROM AUTHOR]

Entropy is a useful indicator of information content that has been used in a number of applications. The Log-Logistic (LL) distribution is a probability distribution that is often employed in survival analysis. This paper addresses the problem of estimating multiple entropy metrics for an LL distribution using progressive type II censoring. We derive formulas for six different types of entropy measurements. To obtain the estimators of the proposed entropy measures, the maximum likelihood approach is applied. Approximate confidence intervals are calculated for the entropy metrics under discussion. A numerical evaluation is performed using various censoring methods and sample sizes to characterize the behavior of estimator's measures using relative biases, related mean squared errors, average interval lengths, and coverage probabilities. Numerical analysis revealed that the accuracy measures improve with sample size, and the suggested entropy estimates approach the genuine values as censoring levels decrease. Finally, an actual dataset was evaluated for demonstration purposes. [ABSTRACT FROM AUTHOR]

In this paper, we study the basket CDS pricing with two defaultable counterparties based on the reduced-form model. The default jump intensities of the reference firms and counterparties are all assumed to follow the mean-reverting constant elasticity of variance (CEV) processes. Taking the Vasicek process which is a special case of CEV process as an example, the approximate analytic solutions of the joint survival probability density, the probability densities of the first default and the first two defaults can be solved by using PDE method. In addition, we also extend the Vasciek process to the Vasciek process with cojumps and obtain the approximate closed-form solutions of the relevant default probability densities. Then with the expressions of the probability densities, we can get the formula of the basket CDS price with two defaultable counterparties. In the numerical analysis, we do sensitivity analysis and compare the basket CDS prices under our model with that with only one defaultable counterparty. The numerical results show that our model can be applied into practice. [ABSTRACT FROM AUTHOR]

In this paper, we examine two structure preserving numerical finite difference methods for solving the various reaction-diffusion models in one dimension, appearing in chemistry and biology. These are the finite difference methods in splitting environment, namely, operator splitting nonstandard finite difference (OS-NSFD) methods that effectively deal with nonlinearity in the models and computationally efficient. Positivity of both the proposed splitting methods is proved mathematically and verified with the simulations. A comparison is made between proposed OS-NSFD methods and well-known classical operator splitting finite difference (OS-FD) methods, which demonstrates the advantages of proposed methods. Furthermore, we applied proposed NSFD splitting methods on several numerical examples to validate all the attributes of the proposed numerical designs. [ABSTRACT FROM AUTHOR]

With the gradual expansion of the book logistics market and the year-on-year increase in book publications, the incidence of book reverse logistics continues to increase, and the problem of book companies' inventory backlog has become increasingly prominent. To effectively alleviate the current backlog of book returns and exchanges, this paper constructs a two-party game model of "book publisher-book retailer," analyzes the evolution process of book publishers and book retailers' participation strategies and the influence of parameter changes on stable strategies through theoretical analysis and numerical simulation, and draws the following conclusions. (1) Whether book publishers and book retailers choose to participate in the reverse logistics optimization of book returns and exchanges is closely related to their benefits and costs, and it also depends on whether the other party participates in the reverse logistics optimization of books. (2) When the cost of participating in book reverse logistics reaches a certain condition, the probability of both parties participating in the optimization is the greatest. [ABSTRACT FROM AUTHOR]

This paper is a study on the elongational deformation induced by pins in pin-barrel cold-feed extruders. The mathematical model is established by using simple flow field, plate model, and Newton constitutive relation. It is proved that there is elongational deformation when the fluid bypasses the pin, and the elongational deformation is quantitatively calculated. The finite element method is used to simulate the flow field of the screw mixing section of the pin-barrel cold-feed extruder with different specifications. The velocity vector nephogram in the simulation results is analyzed by numerical analysis of elongational deformation and compared with the theoretical elongational deformation value. The results show that the simulated and theoretical values of elongational deformation are approximately consistent. The numerical analysis of the key factors affecting the elongational deformation shows that the elongational deformation will gradually increase with the increase of screw diameter. For the screw of the same specification, the increasing helical angle will reduce the elongational deformation, and the increasing rotational speed will linearly increase the elongational deformation in unit time. This study can be used to roughly estimate the elongational deformation induced by pins and establish the mixing theoretical model of the pin-barrel cold-feed extruder. [ABSTRACT FROM AUTHOR]

The VOF (volume of fluid) multiphase transient simulation model of the windage loss of the gear pair under oil-jet lubrication was carried out by using the dynamic mesh technology with the powerful parallel computing capabilities of the Super Cloud Computing Center. Firstly, a two-phase (oil-gas) turbulence numerical model was established in the process of oil-jet lubrication. The numerical simulation test was designed by orthogonal experiment. The influence of the oil-jet lubrication parameters and their interaction on the windage power loss was studied by means of variance analysis. The results showed that the influence of injection speed on the windage power loss was the largest and proportional, followed by injection temperature and injection pressure, and the latter two factors were inversely proportional. Then, the fitting calculation formula of windage loss related to each influencing factor is obtained based on the numerical simulation results. Furthermore, by observing the velocity vector distribution of the internal flow field of the gearbox with different time, the formation mechanism of windage loss is understood intuitively, and the measures to reduce windage loss are put forward. Finally, the mechanical and energy characteristics of the windage loss under different oil injection parameters are proposed, by analyzing and calculating the differential pressure force, viscous force, turbulent kinetic energy, and turbulent dissipation rate around the gear pair. This paper provides a method guidance for the calculation of windage power loss and efficiency of aviation gear pair under elastohydrodynamic lubrication in engineering application. [ABSTRACT FROM AUTHOR]

In order to improve mechanical properties of fly ash/slag concrete with large size cobble as coarse aggregate, this paper analyzes the effect of different factors on the concrete through the flexural strength test. The Monte Carlo simulation is used in the finite element solver of ANSYS to conduct the four-point bending beam test. Three-dimensional and two-dimensional finite element models are established to discuss how the gradation of large size cobbles affects the performance of the concrete by comparing macromechanical experiments. Results show that the gradation of large size cobbles is the main factor affecting the performance of the concrete. Slag generates the least effect on the concrete with cobble as coarse aggregate. When the mixing amount of slag and fly ash is 10%, the concrete presents the best flexural performance. Through the numerical loading test of the two-dimensional model for fly ash/slag concrete with cobble as coarse aggregate, it can be concluded that the change of the concrete follows the law of macromechanical properties. [ABSTRACT FROM AUTHOR]

This paper presents the numerical analysis of prestressed reinforced concrete (PRC) beams strengthened with near-surface mounted (NSM) carbon fiber reinforced polymers (CFRP). ABAQUS finite element software was used to simulate the existing test beams to investigate the flexural behaviors of PRC beams strengthened with NSM CFRP strips. The finite element model of beams strengthened with NSM CFRP strips was established. The finite element calculation results were compared with the experimental results to verify the accuracy and effectiveness of the model. Based on this model, the influences of concrete strength grade and amount of CFRP strips on the flexural behaviors of directly strengthened beams and the cycle numbers and overload amplitude on the flexural behaviors of damaged strengthened beam were further analyzed, and the load-carrying capacity calculation formula of PRC beam strengthened with NSM CFRP strips was established. The results showed that the simulation results and the theoretical calculation were consistent with the test results. With the increase of concrete strength grade and amount of CFRP strips, the ultimate load of directly strengthened beams increased significantly, with a maximum increase of 21.3% and 23.0%, respectively. When the concrete strength grade exceeded C50, the improvement of the ultimate load was limited. When the overload amplitude was less than 60% of the ultimate load, the cycle numbers (within 500 times) had little effect on the yield load, ultimate load, and deformation. When the overload amplitude was higher than 60% of the ultimate load, the deformation increased, and the ultimate load decreased with the increase of the cycle numbers. The larger the overload amplitude, the smaller the ultimate load, and the larger the deformation under the same cycle numbers. [ABSTRACT FROM AUTHOR]

To analyze heat effect in deep metal mines, it is crucial to understand the temperature field distribution around the mine tunnel. In this paper, a numerical model of the random mineral composition of the rock body is established based on finite element software to analyze the influence of the internal composition of the surrounding rock on the temperature field, and a numerical simulation model based on COMSOL finite element software is established based on the two heat exchange modes of heat conduction and heat convection in the surrounding rock. The results show that the numerical simulation results of a typical numerical simulation model using a single material are lower than the real situation; increasing the tunnel length does not increase the heat exchange efficiency between the rock wall and the air; increasing the wind velocity has a limited impact on the temperature field; the wind temperature more directly affects the mining surface; and the effect of wet air on the temperature field of the surrounding rock has a more substantial variation. [ABSTRACT FROM AUTHOR]

This paper presents the nonlinear systems of Volterra-type fractional integro-differential equation solutions through a Chebyshev pseudospectral method. The proposed method is based on the Caputo fractional derivative. The results that we get show the accuracy and reliability of the present method. Different nonlinear systems have been solved; the solutions that we get are compared with other methods and the exact solution. Also, from the presented figures, it is easy to conclude that the CPM error converges quickly as compared to other methods. Comparing the exact solution and other techniques reveals that the Chebyshev pseudospectral method has a higher degree of accuracy and converges quickly towards the exact solution. Moreover, it is easy to implement the suggested method for solving fractional-order linear and nonlinear physical problems related to science and engineering. [ABSTRACT FROM AUTHOR]

With the increasing depth of coal mining and expanding mining scale, the rocks surrounding deep roadways are in a complex mechanical condition of frequent dynamic disturbance. The heterogeneity has an important influence on rock mass failure under dynamic loads. Therefore, it is necessary to study the deformation and failure of heterogeneous roadway under dynamic load. In this paper, the effect of heterogeneity on stability of roadway under static and different dynamic loads is studied. According to the results, the effect of rock mass heterogeneity on the deformation and failure of surrounding rock varies with different degrees of heterogeneity. Under static loading conditions, the stability of roadway is negatively correlated with the degree of heterogeneity of the rock mass. Under dynamic loading conditions, the change of heterogeneity degree has significant influence on the stability of surrounding rock. With the increase in dynamic load strength, the change in variation difference in the average value of roof sag, stress distribution, and plastic zone caused by variations in heterogeneity will increase. This study contributes to understanding the deformation and failure characteristics of heterogeneous roadways under dynamic loads and can be used to analyze heterogeneous roadways under dynamic loads. [ABSTRACT FROM AUTHOR]

The impact attenuator is a safety vehicle system designed to absorb the kinetic energy from a collision that is converted into deformation and ensures the deceleration level acting on the human body remains low. In this paper, we propose that the impact attenuator be fabricated with used cans, which are easy to obtain. Compared to fabricating cylinders through machining and other production processes using new material, the application of used cans may reduce production costs by approximately IDR 500,000 (USD 34.50) for one attenuator structure, while the attenuator still meets the weight criterion, i.e., it has to be light to improve acceleration and fuel efficiency. As a type of metal waste product, food cans are often fabricated from aluminum and other metal alloys. These products are widely used in our lives; if they are not recycled, they can potentially pollute the environment as waste. Given these problems and considering the use of environmentally friendly materials, lightweight used cans were chosen as materials for the proposed impact attenuator design. In the initial study, the verification and validation tests of the impact attenuator shell and used cans show good agreement between the numerical and experimental impact tests. The proposed impact attenuator design under the predetermined parameters showed that used cans of aluminum 6063 series can be recommended as an alternative material in this system. [ABSTRACT FROM AUTHOR]

In the paper, we have considered a nonlinear compartmental mathematical model that assesses the effect of treatment on the dynamics of HIV/AIDS and pneumonia coinfection in a human population at different infection stages. Our model revealed that the disease-free equilibrium points of the HIV/AIDS and pneumonia submodels are both locally and globally asymptotically stable whenever the associated basic reproduction numbers ( R H and R P ) are less than unity. Both the submodel endemic equilibrium points are locally and globally asymptotically stable whenever the associated basic reproduction numbers ( R P and R H ) are greater than unity. The full HIV/AIDS-pneumonia coinfection model has both locally and globally asymptotically stable disease-free equilibrium points whenever the basic reproduction number of the coinfection model R H P is less than unity. Using standard values of parameters collected from different kinds of literature, we found that the numerical values of the basic reproduction numbers of the HIV/AIDS-only submodel and pneumonia-only submodel are 17 and 7, respectively, and the basic reproduction number of the HIV/AIDS-pneumonia coinfection model is max 7 , 17 = 17. Applying sensitive analysis, we identified the most influential parameters to change the behavior of the solution of the considered coinfection dynamical system are the HIV/AIDS and pneumonia transmission rates β 1 and β 2 , respectively. The coinfection model was numerically simulated to investigate the stability of the coinfection endemic equilibrium point, the impacts of transmission rates, and treatment strategies for HIV/AIDS-only, pneumonia-only, and HIV/AIDS-pneumonia coinfected individuals. Finally, we observed that numerical simulations indicate that treatment against infection at every stage lowers the rate of infection or disease prevalence. [ABSTRACT FROM AUTHOR]

To select reasonable PID controller parameters and improve control performances of hydraulic systems, a variable weight beetle antenna search algorithm is proposed for PID tuning in the hydraulic system. The beetle antennae search algorithm is inspired by the beetle preying habit depending on symmetry antennae on the head. The proposed algorithm added the exponential equation mechanism strategy in the basic algorithm to further improve the searching performance, the convergence speed, and the optimization accuracy and obtain new iteration and an updating method in the global searching and local searching stages. In the PID tuning process, advantages of less parameters and fast iteration are realized in the PID tuning process. In this paper, different dimension functions were tested, and results calculated by the proposed algorithm were compared with other famous algorithms, and the numerical analysis was carried out, including the iteration, the box-plot, and the searching path, which comprehensively showed the searching balance in the proposed algorithm. Finally, the reasonable PID controller parameters are found by using the proposed method, and the tuned PID controller is introduced into the hydraulic system for control, and the time-domain response characteristics and frequency response characteristics are given. The results show that the proposed PID tuning method has good PID parameter tuning ability, and the tuned PID has a good control ability, which makes the hydraulic system achieve the desired effect. [ABSTRACT FROM AUTHOR]

This paper studied the fractional-order telegraph equations via the natural transform decomposition method with nonsingular kernel derivatives. The fractional result considered in the Caputo-Fabrizio derivative is Caputo sense. Currently, the communication system plays a vital role in a global society. High-frequency telecommunications continuously receive significant attention in the industry due to a slew of radiofrequency and microwave communication networks. These technologies use transmission media to move information-carrying signals from one location to another. We used natural transformation on fractional telegraph equations followed by inverse natural transformation to achieve the solution of the equation. To validate the technique, we have considered a few problems and compared them with the exact solutions. [ABSTRACT FROM AUTHOR]

In this paper, a full‐wave analytical theory has been proposed based on the field theory approach and numerically solved for computing radiation properties of the dielectric‐loaded helical antenna (DLHA). First, the dispersion equation is analytically derived from the source‐free Maxwell equation subject to necessary boundary conditions. Then radiation characteristics of DLHA are derived using the field theory approach. The effect of polarization current arising due to dielectric on radiation properties is addressed for the first time in the case of DLHA. All the numerical analysis is carried out in MATLAB. To further validate the results, computation analysis is carried out using CST Microwave Studio Software. From the result, it was observed that when the circumference of the antenna (C) is comparable to the wavelength (λ) corresponding to operating frequency then the wave propagates axially through the helical wire in the axial direction and is radiated in the end‐fire direction whereas when the circumference is not equal to the wavelength then the wave gets radiated in the normal direction and attenuated in the axial direction. Also, the impedance bandwidth of the antenna is increased from 2.5% to 52.9% and the gain is increased from 8.35 dB to 11.5 dB due to teflon loading. Finally, the antenna prototype is fabricated, measured, and compared with the numerical and computational results. A close agreement between the analytical, computational, and measurement results are found. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a nonlinear dynamic of permanent magnet synchronous machine scalar drive systems (PMSMSDS) is investigated thoroughly. At first, the mathematical dynamic model of the PMSMSDS is developed and formulated for open‐ and close‐loop cases. Then, constant and periodic load torque are considered for the analysis of the system. The Jacobian matrix and the Poincaré mapping of the system are calculated analytically to study the feasibility of nonlinear phenomena at each point of equilibrium for constant and periodic loads, respectively. Computer simulation is used to obtain bifurcation diagram, time response, and phase plane of the state variables to investigate the complex behavior of the system by changing some parameters. It is shown that by changing the parameters of reference speed command, supply voltage range, and speed controller gain, the response of PMSMSDS state variables will be routed to limit cycle, bifurcated, and chaotic. Numerical analysis is provided to confirm the simulation results. [ABSTRACT FROM AUTHOR]

In this study, a detailed analysis was conducted to evaluate the impacts of the deviatoric stress component and spherical stress component on the stability of surrounding rocks in the roadway via the theoretical analysis and calculation and numerical simulation. Based on the analysis, the distribution laws guiding the main stress differences, plastic zone, convergence of surrounding rocks, and third invariant of stress under various conditions (such as equal spherical stress and unequal deviatoric stress and equal deviatoric stress and unequal spherical stress) were developed, providing an optimization scheme for roadway support misunderstanding under the conditions of high spherical stress field and high deviator stress field. The study further reveals that under the circumstance of the constant spherical stress, the greater the deviatoric stress, the plastic zone range of the surrounding rock of the roadway, the range of tensile deformation of the surrounding rock, the amount of convergence of the surrounding rock, the probability of separation of the roof and floor of the roadway, and the principal stress difference and the main stress, the greater the concentration range of the maximum stress difference is, and the maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway, and the greater the deviatoric stress, the greater the probability that the roof and floor rocks of the roadway will be separated, and the maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway, the greater the deviator stress, the greater the concentration range of the maximum value of the principal stress difference and the principal stress difference; when the deviator stress is constant, the range of the plastic zone and the maximum principal stress difference concentration range of the surrounding rock of the roadway decrease with the increase of the ball stress, and the principal stress difference, the amount of convergence of the surrounding rock, and the range of tensile deformation increase with the increase of the ball stress. The maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway. The principal stress difference increases with the increase of the spherical stress, and the maximum concentration range of the principal stress difference decreases with the increase of the spherical stress. After the method proposed in this paper optimizes the actual roadway support on site, the surrounding rock deformation of the roadway is small and the control is relatively ideal, which basically meets the engineering needs. [ABSTRACT FROM AUTHOR]