Search

In order to provide a theoretical basis for the precise finite element method (FEM) analysis of the long-range operation structural behavior of concrete faced rockfill dams (CFRDs), an improved creep model and the parameter spatial estimation method under digital construction were proposed. Creep characteristics of rockfill materials were studied by large-scale indoor triaxial creep test. The precision of traditional creep model was analyzed, and an improved model was proposed. The average fitting accuracy of the test results improved by 32.9% compared to the traditional model, which greatly improves the accuracy of creep characterization. Then, two models were applied for the FEM calculations of the dam under different porosities. The maximum relative difference of dam settlement brought by the two models was 60.6%. On this basis, the abnormal early warning curves of dam deformation and face deflection were proposed. Furthermore, the regression models between porosity and improved model parameters were established. Finally, the parameter spatial estimation of the improved model was achieved relying on the digital construction technology. This method takes into account the spatial variations of the mechanical parameters of dam materials, thus aligning more closely with the actual conditions. [ABSTRACT FROM AUTHOR]

The potential of monitoring the movement of typhoons using the precipitable water vapor (PWV) has been confirmed. However, monitoring the movement of typhoon is focused on PWV, making it difficult to describe the movement of a typhoon in detail minutely and resulting in insufficient accuracy. Hence, based on PWV and meteorological data, we propose an improved typhoon monitoring mode. First, the European Centre for Medium-Range Weather Forecasts Reanalysis 5-derived PWV (ERA5-PWV) and the Global Navigation Satellite System-derived PWV (GNSS-PWV) were compared with the reference radiosonde PWV (RS-PWV). Then, using the PWV and atmospheric parameters derived from ERA5, we discussed the anomalous variations of PWV, pressure (P), precipitation, and wind speed during different typhoons. Finally, we compiled a list of critical factors related to typhoon movement, PWV and P. We developed an improved multi-factor typhoon monitoring mode (IMTM) with different models (i.e., IMTM-I and IMTM-II) in different cases with a higher density of GNSS observation or only Numerical Weather Prediction (NWP) data. The IMTM was evaluated through the reference movement speeds of HATO and Mangkhut from the China Meteorological Observatory Typhoon Network (CMOTN). The results show that the root mean square (RMS) of the IMTM-I is 1.26 km/h based on ERA5-P and ERA5-PWV, and the absolute bias values are mostly within 2 km/h. Compared with the models considering the single factor ERA5-P/ERA5-PWV, the RMS of the IMTM-I is improved by 26.3% and 38.5%, respectively. The IMTM-II model manifests a residual of only 0.35 km/h. Compared with the single-factor model based on GNSS-PWV/P, the residual of the IMTM-II model is reduced by 90.8% and 84.1%, respectively. These results propose that the typhoon movement monitoring approach combining PWV and P has evident advantages over the single-factor model and is expected to supplement traditional typhoon monitoring.

When a gas-liquid two-phase flow (GLTPF) enters a parallel separator through a T-junction, it generally splits unevenly. This phenomenon can seriously affect the operation efficiency and safety of the equipment located downstream. In order to investigate these aspects and, more specifically, the so-called bias phenomenon (all gas and liquid flowing to one pipe, while the other pipe is a liquid column that fluctuates up and down), laboratory experiments were carried out by using a T-junction connected to two parallel vertical pipes. Moreover, a GLTPF prediction model based on the principle of minimum potential energy was introduced. The research results indicate that this model can accurately predict the GLTPF state in parallel risers. The boundary of the slug flow and the churn flow in the opposite pipe can be predicted. Overall, according to the results, the pressure drop curves of the two-phase flow in the parallel risers are basically the same when there is no bias phenomenon, but the pressure drop in the parallel riser displays a large deviation when there is a slug flow-churn flow. Only when the parallel riser is in a state of asymmetric flow and one of the risers produces churn flow, the two-phase flow is prone to produce the bias phenomenon. [ABSTRACT FROM AUTHOR]

Aiming at the actuator failure in the work of unmanned underwater vehicle (UUV), an adaptive robust fault-tolerant control method based on finite time disturbance observer (FTDO) and improved model was proposed under system uncertainty and external interference. On the one hand, the external environmental interference could be estimated by FTDO in a limited time. On the other hand, sliding mode control and the universal approximation characteristics of radial basis function neyral network(RBF) were used to establish input compensation with actuator fault. Among them, the input saturation caused by system uncertainty was solved by the improved model, which improved the stability and robustness. Secondly, a new type of double-power approximation law was adopted to make the sliding modulus converge to the steady-state error range in a shorter time. The simulation and pool experimental results show that the proposed method has a better fault tolerance effect than the sliding mode control. [ABSTRACT FROM AUTHOR]

This work presents the experimental characterization and improved model of multi-strand entangled metallic wire materials (MS-EMWMs). MS-EMWM is a novel damping material made of several strands of entangled wires using a modified manufacturing process. Six batches of specimens were fabricated and tested under quasi-static loading. Secant stiffness and loss factor were calculated to indicate the mechanical properties. The results showed that MS-EMWM has the characteristics of high damping energy dissipation compared to EMWM. A micro-multi-strand spiral spring model was proposed to predict the mechanical properties of MS-EMWM. The probability distribution of micro-spring pairs between wires was used to characterize the random combination of materials. According to the results, the improved model can effectively reflect the mechanical behavior of MS-EMWM. The mechanical properties of MS-EMWM were predicted by the coefficient matrix obtained by particle swarm optimization. Through the prediction and test results, the predicted results are acceptable. [ABSTRACT FROM AUTHOR]

The YOLO-based algorithm is one of the hot research directions in target detection. In recent years, with the continuous proposition of YOLO series algorithms and their improved models, the YOLO-based algorithm has achieved excellent results in the field of target detection and has been widely used in various fields in reality. This article first introduces the typical datasets and evaluation index for target detection and reviews the overall YOLO framework and the development of the target detection algorithm of YOLOv1~YOLOv7. Then, models and their performance are summarized across eight improvement directions, such as data augmentation, lightweight network construction, and IOU loss optimization, at the three stages of input, feature extraction, and prediction. Afterwards, the application fields of YOLO algorithm are introduced. Finally, combined with the actual problems of target detection, it summarizes and prospects the development direction of the YOLO-based algorithm. [ABSTRACT FROM AUTHOR]

A systematic study was conducted to investigate the distinct mechanisms involved in the formation of the inner surfaces of cylindrical and parallelepipedic-shaped structures. The surface roughness, flatness, and sinking distance were used as key indices to measure the quality of overhanging surfaces, while the surface flatness and roughness were used to evaluate the quality of the side and bottom surfaces of the inner hole. The inner surface morphology was observed using a scanning electron microscope and a white light interferometer. The test results show that the quality of the overhanging surface had a significant impact on the quality of the parallelepipedic-shaped inner hole. In contrast, the cylindrical-shaped inner hole had a shorter but more uniformly distributed overhanging surface, resulting in a different behavior of the overhanging and side surface quality. An improved model of the overhanging surface was established by combining all of the above results and comparing them with the traditional Euler Bernoulli beam model. The factors affecting the quality of the overhanging surface were analyzed, and measures for improving the quality of the overhanging surface during the SLM manufacturing process were proposed. [ABSTRACT FROM AUTHOR]

Abstract Dynamic analysis for a bearing-rotor system with the imbalance and the asymmetric gap is conducted in this paper. A new improved analytical model overall considering the gap, the varying compliance vibration and the time-dependent unbalanced force is established, especially the new model is more accurate and closer to reality by abandoning the assumption of the traditional model that the three center points of the inner ring, the outer ring and the rolling ball are collinear. More general vibration characteristics are described and the calculation results based on the new model are more universal than those based on the traditional model. The comparison of the calculation result between the improved model and the traditional model shows that the phase difference for the two results is obviously different from each other, the dominant frequency has no obvious difference between the two models and the amplitudes have somewhat difference. The parametric excitation vibration induced by the varying compliance force of the rolling ball on the inner ring-rotor is analyzed and then the influences of the rotating speed, the gap, the eccentricity and the mass of the rotor on the nonlinear responses are studied and some important conclusions are drawn. As the speed increases, the VC frequency gradually loses its domination of the frequency spectrum, and the rotational speed frequency and its combined frequency with the VC frequency dominate the vibration. The bearing-rotor system is susceptible to the variations of the rotational speed, the gap, the eccentricity and the mass of the rotor in certain ranges; the parameters can make the system in a relatively stable, stable and unstable state; the system shows the complex dynamic behaviors such as the periodical vibration, the quasi-periodic vibration, the chaotic motion and the jumping phenomenon, the bifurcation, sudden change. The research is significant for the quantitative calculation of the dynamic response for parameter designation and the fault diagnosis of the system.

Various models and equations of water vapor sorption (WV) for hydrophilic polymers were considered. However, these models often do not correspond to the sorption mechanism. The new model proposed in this paper is based on the thermodynamics of binary systems and its combination with the Van Krevelen method of polar group contributions in the sorption of WV. It was shown that the mechanism of WV sorption by various hydrophilic polymers is the absorption of water molecules in the volume of amorphous domains of these polymers. Based on the developed model, a universal physicochemical equation was derived, which makes it possible to adequately describe the sorption isotherms of WV by amorphous hydrophilic polymers knowing only the chemical formulas of repeating units of these polymers. To calculate the sorption isotherms for semicrystalline samples, it is necessary to use an additional parameter, namely the degree of amorphicity (Y). The adequacy of the proposed equation was verified for samples of cellulose and other natural polysaccharides, as well as for samples of synthetic hydrophilic polymers such as polyvinyl alcohol, polyamide-6, and polycaprolactone having various Y-values. The verification showed that the experimental isotherms are almost identical to the isotherms calculated by the universal equation. [ABSTRACT FROM AUTHOR]

The data of the regular bus in Shenzhen during October 2019 was taken as an example. The improved model for the public transportation assignment was established based on considering the interval uncertainty theory and the basic algorithm of interval value, and the interval value acquisition method of bus impedance is established, the Method of Successive Averages ( MSA) algorithm is used to solve the problem. Finally, the error analysis of bus passenger flow assignment before and after the improvement of the model is carried out. It is found that the average absolute percentage error of the improved assignment model is 8.7% compared with the real value, while the average absolute percentage error is 10.9% when the impedance is invariant value, The result of passenger flow assignment under interval impedance is obviously better than that under certain impedance. On non-working days, when the bus passenger flow changes greatly, the bus passenger flow assignment result under interval impedance is better.

The error between the actual damping force and the simulated damping force obtained using the Bouc–Wen model under non-identification excitation conditions is large, and the model is too sensitive to non-identification excitation amplitude and thus features poor accuracy. To solve this sensitivity problem, an improved model describing hysteretic characteristics of shock absorbers was proposed. Firstly, the mechanical properties of a magnetorheological (MR) damper were tested to obtain the damping force under various excitation amplitudes, frequencies and currents using a mechanical testing and simulation(MTS) fatigue testing machine. The smooth hysteresis loop curve was simulated based on the relationship between the slope of the hysteresis loop and the damping force. The quadratic polynomial function was used to characterize the relationship between the slope of hysteresis loop and the damping force according to the hysteresis curve characteristics. At the same time, the revision term of the exponential function for the velocity value was introduced, and the parameters of the established improved Simulink model were identified. The damping forces under different working conditions were obtained from the experiment, and the new model was simulated and validated. The damping forces obtained from new model and the experiment were compared, and the curves obtained from the model agree well with the experimental results under different working conditions. Meanwhile, the improved model was compared with the Bouc–Wen model based on the characteristic curves of the damping force. The results show that the improved model can better simulate the damping force values obtained from tests under different conditions, and is superior to the Bouc–Wen model. At the same time, the problem of poor accuracy of the Bouc–Wen model under non identification excitation conditions was improved. The new model lays the foundation for ensuring the accuracy of the vehicle suspension system response under various working conditions.

From August 4th to 30th, 2020 and from November 27th to December 25th, 2020, a self-developed radiosonde balloon system was used to observe high-altitude atmospheric optical turbulence at three sites in northwestern China, and an improved model based on the observational data was established. Through comparative analysis of the observational data and the improved model, the distribution characteristics of atmospheric optical turbulence under the combined action of different meteorological parameters and different landform features in different seasons were obtained. The improved model can show the variation of the detailed characteristics of turbulence with the height distribution, and the degree of correlation with the measured values is above 0.82. The improved model can provide a theoretical basis and supporting data for turbulence estimation and forecasting in northwestern China. [ABSTRACT FROM AUTHOR]

With the continuous development of deep learning, its drawbacks are also beginning to appear. As an alternative to deep learning, broad learning is emerging. However, the level of broad learning model is shallow, so feature learning is not sufficient. In order to solve two problems of small samples whose dimensions are not very high in network model training, it cannot be adequately trained in the deep learning model and the features of input data cannot be fully learned in the broad learning model. This paper attempts to add a hidden layer on the enhancement nodes of the broad learning model and do shallow learning for the enhanced features to learn the hierarchical features again. This improved broad learning model also provides a new idea for solving the problem of small samples. From the perspective of regression and classification, this paper proves that for small samples whose dimensions are not very high, the effect of the improved broad learning model is better than that of the original broad learning model and also proves that the improved broad learning model has a good ability of application. This shows that the broad learning model based on enhanced features learning has the necessity and feasibility of further research.

Conventional AlexNet has the problems of slow training speed, single characteristic scale and low recognition accuracy. To solve these problems, a convolutional neural network identification model based on Inception module and dilated convolution is proposed in this study. The inception module combined with dilated convolution, could extract disease characteristics at different scales and increase the receptive field. By setting different parameters, six improved models were obtained. They were trained to identify 26 diseases of 14 different crops; then the authors selected optimal recognition model. On this basis, the segmented dataset and the grey‐scaled dataset were trained as comparative experiments to explore the influence of background and colour features on the recognition results. After only two training epochs, the improved optimal model could achieve an accuracy of over 95%. Moreover, the final average identification accuracy reached 99.37%. Contrast experiments indicate that colour and background features may influence the recognition effect. The improved model can extract disease information from different scales in the feature map to identify diverse diseases of different crops. The proposed model has faster training speed and higher recognition accuracy than the traditional model, and thus it can provide a reference for crop disease identification in actual production. [ABSTRACT FROM AUTHOR]

At present, the recognition method based on character segmentation is not effective in recognizing English text, and the traditional methods are based on the structural features and statistical characteristics of strokes. In order to improve the recognition effect of in English text, from the perspective of machine learning, this study introduces multi-features to improve the lack of information caused by the small Chinese data set. Moreover, this study disassembles the character recognition problem into a text matching problem of question and answer, and the textual entailment problem of answer and standard answer and continues training on the data set of short text score. The final result has a certain improvement, which proves the usability of the mechanism designed in this paper. In order to study the performance of the model proposed in this paper, the model proposed in this paper and the neural network recognition model are compared in terms of recognition accuracy and recognition speed. The research results show that the algorithm proposed in this paper has a certain effect. [ABSTRACT FROM AUTHOR]

At present, data is in a state of explosive growth. The rapid growth of data collected by enterprises has exceeded the processing capacity of traditional human resource management systems, resulting in their inability to perform data management and data analysis. In order to improve the practicality of the human resource management system, this paper applies machine learning technology to the human resource management system, selects dimensions according to the prediction method, and builds a combined model consisting of an optimized GM (1,1) model and a BP neural network model. The model is implemented by a three-layer BP neural network. In order to verify the performance of the research model, this article conducts research using an entity as an example. The research results show that the method proposed in this paper has certain practical effects and can improve the reference for subsequent related research. [ABSTRACT FROM AUTHOR]

The model used for the interaction between the pipe and the soil is to use a soil spring to transfer the load to the pipe. The basis of the selection of soil spring parameters is based on laboratory test, and the test site is a flat site. Therefore, laboratory results may not be effective for pipe-soil interface simulation and slip-wave conditions. Moreover, the load and soil spring coefficient of the pipeline in the abrupt slope and landslide should vary with space and time, these factors are ignored by current general rules. In this paper, we deduced the soil spring resistance formula when the ground is tilted, and the improved soil spring model of the abrupt slope and landslide section is established, and the variation law of the resistance of the various soil springs under different ground angles is obtained. The improved soil spring model of the abrupt slope and landslide section we have established has certain guiding significance for the calculation of the interaction between the soil and the abrupt slope and landslide section. [ABSTRACT FROM AUTHOR]

Multiple groups of triaxial shear tests and creep tests were performed on rockfill materials, stress–strain, volume-strain, volumetric creep-time and axial creep-time curves were obtained under different porosity levels. Based on the analysis of the test results, the improved Shen Zhujiang double yield surface elastic–plastic model and the improved creep model were proposed for deformation prediction with higher accuracy, and they were incorporated into the calculation program for concrete face rockfill dams (CFRDs) by program development. Afterward, the regression models were established between the porosity and the parameters of the improved models, which offer quick derivation of the model parameters by porosity under the condition that lithology and gradation are basically the same. Furthermore, relying on digital construction technology, the spatial distributions of model parameters within the entire dam were estimated. Finally, a set of improved model parameters reflecting actual construction quality was assigned to an element, and the refined finite element method (FEM) numerical simulation of the long-term deformation of the CFRD considering the actual construction quality was realized. The engineering example shows that the proposed method can greatly improve the simulation accuracy of the long-term service behavior of the CFRDs. [ABSTRACT FROM AUTHOR]

Organic Rankine cycle combined ejector expansion refrigeration cycle (ORC-EERC) has significant potential for utilizing low-temperature heat. The study on dynamic response of the ORC-EERC combined system plays a particularly important role in optimizing the control strategy for the system, given the instability of the low-temperature heat source. In this paper, the ORC-EERC dynamic models with single and dual condensers are proposed. The simulation results show that the proposed improved model of EERC subsystem presents more accurate results relevant to the experiment system. The impact of the ORC subsystem on the refrigeration subsystem is more pronounced in the ORC-EERC system with a single condenser than in the system with dual condensers. In addition, the phenomenon of chocking in the ejector throat leads to the degradation of system performance when the heat source is disturbed. Therefore, a multi-device cooperative control strategy is proposed to enhance the safety and performance of the system. In the case study of geothermal water mass flow scheduling disturbance, the control strategy increases the cooling capacity of the system by a maximum of 9.29%. • The Simulation results of the improved model are closer to the experimental values. • The dynamic response of ORC-EERC with single and dual condensers are compared. • A cooperative control strategy is proposed to improve the system performance. • The dynamic response of the system under geothermal water scheduling is analyzed. [ABSTRACT FROM AUTHOR]

For ultra‐rapid orbits provided by the Global Navigation Satellite System (GNSS), the key parameters, accuracy and timeliness, must be taken into consideration for real‐time and near real‐time navigation and positioning applications. With reference to the low accuracy in observed orbits (last 3 hours), an improved model based on the orbit dilution of precision (DOP) values is proposed by building the function models between DOP values and the orbit accuracy. Firstly, the prediction model of the DOP values is set based on observations and Akaike information criterion. Secondly, the function model between orbit accuracy and DOP values is built.At last, the predicted DOP values with highly precision are taken into orbit correction model to improve the observed ultra‐rapid orbit accuracy. With the comparison experiments, it is found that there is a correlation between the DOP values of orbit parameter and its precision, and the variation trend of DOP values can be fitted based on polynomial model. Furthermore, to verify the availability of im ‐ proved model, two experiment schemes were designed from the aspect of the length of observations and prediction models. In addition, there are no significant differences of orbit correction for different function models. With 10‐day orbit determination experiments, the results show that the observed ultra‐rapid orbit errors, generated by insufficient observations, can be corrected by 12.4%‐22.0% for the last 3 hours of the observed orbits. Thus, the observed ultra‐orbit correction model of our proposed is meaningful and can im ‐ prove the ultra‐rapid orbit accuracy of GNSS analysis center. [ABSTRACT FROM AUTHOR]

At present, there is less software related to sport technical behavior recognition, and there are few studies on the classification and identification of detailed actions. By introducing computer technology to analyze the efficiency and regularity of sports, not only the characteristics of athletes can be excavated, but also the visibility and dynamic tracking of sport training can be provided. The process of sports education is a fast and complex systematic process. Through the interactive system of physical education, we can use different methods to collect sports data and make a comparative analysis of athletes' movements. Through the data mining of the relationship between athletes' physiological indexes and sports load, the unreasonable link in sports training can be avoided. Also, in sports training, we can use computer vision and modern biomechanics to construct a virtual sports education situation. With the classification accuracy as the fitness function, this paper collects the data through the network database, and returns the corresponding sport training parameters on this basis. The results showed that the accuracy of the model was nearly 98%, which met the actual demand. Therefore, the development of sports education assistant system can provide strong support for the process control of sports training and education. [ABSTRACT FROM AUTHOR]

As the core material of an electrical device, the electrical steel sheet is often under ac and dc-biased magnetizing conditions due to the wide utilization of power electronics. For an accurate description of rotating magnetic properties of electrical steel sheet under the dc-biased field, an improved model considering magnetic hysteresis and nonlinear magnetization characteristics is established. The reluctivity coefficients and hysteresis coefficients of the improved model are calculated from magnetic flux density and magnetic field intensity waveforms measured by the feedback control system. The accuracy and reliability of the improved model are verified by the comparison of the measured and calculated hysteresis loops of electrical steel sheet under the dc-biased field. [ABSTRACT FROM AUTHOR]

It's generally known that ocean stores abundant energy resources for the development and growth of human beings. Nowadays, the sustainable development of marine economy calls for precisely speculation of marine energy prices and efficiency. However, the traditional methods of measuring energy price and efficiency, for instance, the EROI (energy return on investment) model unable to define system boundaries and to calculate labor and physical costs, be it tidal energy or marine biomass energy. Thus, these methods may ignore as much as 50% of input energy consumption. Energy efficiency could be calculated by the ratio of average energy input cost to the average useable energy output cost while energy price could be measured by the ratio of the monetary input to the output. The principle above could be viewed as a check for energy return on investment as well as an elimination for a redundant process analysis. The results give us a chance to innovate traditional energy efficiency model by social and environmental factors which could be depicted through monetary terms. The precise estimation of marine energy efficiency could also help us make appropriate policies to combat global warming. [ABSTRACT FROM AUTHOR]

In this paper, we propose a theoretically derived improved model for characterizing the fractal features of coalbed methane reservoirs, and we compare with previously published models for conventional reservoirs. The model was verified by mercury intrusion porosimetry. The results have shown that there is no linear relationship between the normalized wetting phase saturation, wetting phase saturation, or mercury saturation vs. the capillary pressure on a log-log plot. Therefore existing models are inapplicable for a high-rank CBM formation, which is characterized by low permeability and porosity. The improved model lets us calculate the multi-interval fractal features characterizing the physical properties of the formation. We show that higher fractal dimensions mean poorer physical properties of the formation. [ABSTRACT FROM AUTHOR]

Elber and Walker's effective stress intensity factor range model and Kujawski's two-parameter driving model were used for the normalization of the Crack growth curves under different stress ratios(R). These two models were applied under the condition that the stress ratio only affected the position of crack growth rate curves, but not their shapes. When crack growth curves under different stress ratio were normalized, these two models were only applicable to the intermediate-regions of crack growth threshold. A new improved two-parameter driving model was proposed, which is appropriate for intermediate-region and accelerated region of crack growth curves. In this model, the exponents are a function of these parameters: stress ratio, fracture toughness, stress intensity and the parameter calculated from the two-parameter driving model, when fatigue crack growth rate tends to infinity. The crack growth curves under different R can be normalized into one curve by using this new improved two-parameter driving model, which has different shape in the intermediate-region and accelerated region. The modified two-parameter model was verified by the fatigue crack growth data of PMMA (YB-MD-11 and YB-MD-3) and titanium alloy (Ti-1023). [ABSTRACT FROM AUTHOR]

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Many complex vacuum systems include edge-welded bellows. Their simulation in the molecular flow regime with a Test Particle Monte Carlo (TPMC) code, such as MolFlow+, can take considerable amounts of computing power and time. Therefore we investigated the change of the transmission probability of a bellow compared to a cylindrical tube in TPMC simulations. The results were used to develop an empirical model to simplify the geometry of a bellow in a TPMC model by replacing it with a cylindrical tube of extended length, consequently compensating the reduced conductance of the bellow. The simulated transmission probabilities of a variety of different bellow lengths have been used to fit the parameters of the model. Each bellow geometry simulated with MolFlow + comprised two cylindrical tubes, one at each end, and the central bellow section. The geometry of each bellow is described by two quantities. The first one is the total length of the geometry model normalized to the inner diameter of the bellow. The second one is the fraction of the bellow section with regard to the total length. Simulating a tube instead of a long bellow reduced the simulation time by a factor of up to 1000, while the error introduced through the replacement of the bellow with a cylindrical tube of modified length was in most cases negligible. Highlights • Simulation of the transmission probability of edge-welded bellows (TPMC model). • Deduce a simplified empirical model to estimate the transmission probability of a bellow. • Apply the model to replace the complex bellow geometry in a TPMC simulation by a cylindrical tube. • Reduce the simulation time by several orders of magnitude. [ABSTRACT FROM AUTHOR]

Published diffuse X-ray scattering from the high-Tc superconductor HgBa2CuO4+δ has been reexamined with a view to developing a model that more satisfactorily accounts for the observed patterns. The present work agrees with the previous conclusion that the doping oxygen atoms form long and isolated interstitial chains that run in both tetragonal directions. However, a distinctly different model is proposed for the accompanying displacement patterns of the atoms surrounding these linear defects. In this new model it is proposed that it is the correlated shifts of the Ba atoms along the length of the defect chains that are the primary source of the observed scattering, and that the variations of intensity in the generated diffuse streaks of scattering originate from lateral shifts of both Hg and Ba atoms away from defects. The new model yields diffraction patterns that are in much more convincing agreement with the observations than the original model.

Complete animal models investigating the pathogenesis and treatment of polycystic ovarian syndrome (PCOS) are not completely established. Although dehydroepiandrosterone (DHEA)-induced pre-pubertal rat model for PCOS has been widely used, the model exhibits weaknesses such as decreased ovary weight. Here, we report an innovative DHEA-induced PCOS model that addresses limitations of the pre-pubertal model. The 21-day-old (pre-pubertal) and 42-day-old (post-pubertal) female rats were subcutaneously injected with DHEA (60 mg/kg body weight) daily for up to 20–30 days. The post-pubertal model showed a steady increase in ovary weight and the number of ovarian cysts as well as uterine weight and thickness, which may be key features of PCOS, compared with the pre-pubertal model. Therefore, a post-pubertal PCOS model induced by DHEA may be an improved model to investigate the etiology of PCOS and development of therapeutic interventions.

To compare the differences in water resource consumption among hydropower projects in the Lancang-Mekong River basin, we chose 37 hydropower plants as examples. Based on an analysis of remote sensing data, the water footprints of these hydropower plants in 2015 were analyzed using the improved water footprint method. The results revealed that the hydropower plants in Lancang River basin, which have the smallest water footprint of hydropower plants in China, indicating a high efficiency of electricity production. In contrast, the hydropower plants in the Mekong River basin located in Laos and Thailand had a larger water footprint, suggesting a low efficiency of electricity production and high consumption of water resources. Therefore, from the perspective of power generation efficiency and water resources consumption, the upstream section in China is more suitable for hydropower development, and the influence of water resources consumption in hydropower should be appropriately considered in downstream countries. [ABSTRACT FROM AUTHOR]

With the globalization and rapid development every filed is taking an increasing interest in physical geography and human economics. There is a surging demand for small scale world map in large formats all over the world. Further study of automated mapping technology, especially the realization of small scale production on a large scale global map, is the key of the cartographic field need to solve. In light of this, this paper adopts the improved model (with the map and data separated) in the field of the mapmaking generalization, which can separate geographic data from mapping data from maps, mainly including cross-platform symbols and automatic map-making knowledge engine. With respect to the cross-platform symbol library, the symbol and the physical symbol in the geographic information are configured at all scale levels. With respect to automatic map-making knowledge engine consists 97 types, 1086 subtypes, 21845 basic algorithm and over 2500 relevant functional modules. In order to evaluate the accuracy and visual effect of our model towards topographic maps and thematic maps, we take the world map generalization in small scale as an example. After mapping generalization process, combining and simplifying the scattered islands make the map more explicit at 1:2.1 billion scale, and the map features more complete and accurate. Not only it enhance the map generalization of various scales significantly, but achieve the integration among map-makings of various scales, suggesting that this model provide a reference in cartographic generalization for various scales. [ABSTRACT FROM AUTHOR]

The Liao river is one of the seven major rivers in China, and the process of phosphorus (P) cycling and change of water quality in this basin are influenced to a considerable extent human activities. In this work, the traditional net anthropogenic phosphorus inputs (NAPI) model was improved by considering the dynamic change of wastewater treatment capacity and P deposition (PDEP) and reclassifying the sources of phosphorus into human P consumption (PHUM), agriculture P consumption (PAGR), livestock P consumption (PANIM) and PDEP to analyze its dynamic spatio-temporal change in the Liao river basin. The results showed that the annual mean NAPI was 785.53 kg P km−2 yr−1 (2001–2020), the maximum value was 940.49 kg P km−2 yr−1 in 2009, and the minimum value was 586.04 kg P km−2 yr−1 in 2001. The temporal variation of NAPI presented an increasing-fluctuation-increasing trend and was basically in line with that of the water quality throughout the three stages, and the spatial distribution of NAPI gradually increased from upstream to downstream. During the two decades, PANIM was the predominant component of NAPI with a share of 64.32%. PHUM, PAGR, and PDEP accounted for 15.97%, 11.54%, and 8.17%, respectively, and the point source NAPI (NAPIP) contributed to 4.95% of NAPI. Further, the INAPI (Improved NAPI) -MR (Multiple Regression) -SWAT (Soil and Water Assessment Tool) model was developed to predict the spatial distribution of P flux under two scenarios. The results showed that the Liao river basin experienced a reduction in P flux to different degrees due to the improvement of the wastewater treatment system, which was more significant in its downstream area. Long-term water quality monitoring is encouraged to develop refined water quality models in the future. [Display omitted] • Dynamic wastewater phosphorus removal was considered to improve NAPI model. • Spatiotemporal change of NAPI in the Liao river basin was investigated at city level. • INAPI-SWAT-MLR model was developed to describe the P flux across the basin. [ABSTRACT FROM AUTHOR]

Viscoelastic pipeline conveying fluid is analyzed with an improved variable fractional order model for researching its dynamic properties accurately in this study. After introducing the improved model, an involuted variable fractional order, which is an unknown piecewise nonlinear function for analytical solution, an equation is established as the governing equation for the dynamic displacement of the viscoelastic pipeline. In order to solve this class of equations, a numerical method based on shifted Legendre polynomials is presented for the first time. The method is effective and accurate after the numerical example verifying. Numerical results show that how dynamic properties are influenced by internal fluid velocity, force excitation, and variable fractional order through the proposed method. More importantly, the numerical method has shown great potentials for dynamic problems with the high precision model.

As a very important second messenger, Ca 2+ plays the role of adjusting various cellular physiological processes through calcium oscillations. In this paper, a further theoretical study is conducted to explore the kinetic behavior of the calcium signals based on a mathematical model. At first, the causes behind the appearance and disappearance of calcium oscillations are strictly verified from the theoretical level and a comparative analysis between the improved model and the original model is also made. Then, it is found that with the increase of relaxation time, the second bifurcation point of the system moves towards the increasing direction of the stimulus intensity and the oscillation interval displays gradual increase. It is also found that under given stimulus intensity, with the relaxation time getting longer, both the peak value and the period of the calcium oscillations display significant increase. Combining the results from the comparative analysis between the improved model and the original model with the results from the analysis of the relaxation time, it shows that the calcium pump activity exerts a direct impact on the calcium oscillation interval. Finally, the calcium leakage item is introduced into the improved model and it is found that as the calcium leakage increases, the two Hopf bifurcation points of the system both move towards the decreasing direction of the stimulus intensity and the oscillation interval gradually narrows down. The study also shows that under given stimulus intensity, as the calcium leakage increases, the peak value of the calcium oscillations displays slow increase and the oscillation period displays gradual decline. [ABSTRACT FROM AUTHOR]

Soil physical basic parameters are key factors for impacting the soil thermal conductivity, and they are also closely related to the model parameters used to calculate the soil thermal conductivity. In order to study the relationship between soil physical basic parameters, organic matter content and soil thermal conductivity model parameters, the precision of different soil thermal conductivity models was discussed by analyzing 10 types of soil samples in this paper. There were 9 types of soil textures which were sampled from different areas in Shaanxi Province, and the last one was sampled from Zhangye, Gansu Province, which was used to verify the feasibility of the new models. According to the sand content, these soil samples were divided into 2 types: fine-textured soil and coarse-textured soil. The soil thermal conductivity models were used to fit these 2 types of soils, and the comparison results indicated that the theoretical models such as Côté-Konrad model and Lu-Ren model were more precise than Campbell model and Johansen model. The fitted results of Johansen model were significantly smaller than the measured values, and the ranges of root mean square error (RMSE), coefficient of determination (R2) and relative error (Re) for this model were 0.0848-0.2548, 0.656-0.827 and 10.32%-20.41%, respectively. Moreover, Côté-Konrad model and Lu-Ren model had better fitting results for fine-textured soil, and the ranges of RMSE, R2 and Re were 0.0810-0.1208, 0.842-0.940 and 9.67%-10.57% for Côté-Konrad model and 0.0725-0.1238, 0.874-0.937 and 8.28%-9.91% for Lu-Ren model. However, these 2 models were not suitable for calculating the soil thermal conductivity of coarse-textured soil when the water saturation was larger than 50%. Thus, the improved models, which described the relationship between thermal conductivity and soil physical basic parameters, were developed based on Côté-Konrad model and Lu-Ren model. The results showed that the improved models could be used to fit the thermal conductivity in different soil textures, and the RMSE was less than 0.0964, the R2 was up to 0.92 and the Re was less than 9.6%. For predicting the soil thermal conductivity with higher sand content or higher silt content, the values of RMSE, R2 and Re for the improved Côté-Konrad model were 0.1183, 0.9259 and 9.47%, respectively, which was better than the Côté-Konrad model, Lu-Ren model, and improved Lu-Ren model through the analysis of simulation error. On the other hand, for predicting the soil thermal conductivity with lower sand and silt contents, the values of RMSE, R2 and Re for the improved Lu-Ren model were 0.0815, 0.9326 and 8.11%, respectively, which was better than the other 3 models. Moreover, the improved models were used to calculate the soil thermal conductivity of the other types of soil textures in Zhangye. Because the soil texture in Zhangye is sandy clay loam soil in which the sand content is higher than 60%, the improved Côté-Konrad model has the best effect when calculating the soil thermal conductivity according to the analysis results. The parameters in the improved models contain soil texture and organic matter content, which can be used to describe the relationship between thermal conductivity and soil physical basic parameters in detail. Furthermore, choosing an appropriate improved model based on soil texture can calculate the soil thermal conductivity more accurately. [ABSTRACT FROM AUTHOR]

In this study, we explain the causes and effects of the geometrical impossible result encountered in the widely adopted tetrakaidecahedron model (Boomsma and Poulikakos, 2001; Dai et al., 2010) for the effective thermal conductivities (ETCs) of metal foam. The geometrical impossible result is successfully eliminated by accounting for the size variation of the node with porosity. The improved model provides predictions of ETCs that are more precise than available models. For aluminum foams ( k s = 218 W m - 1 K - 1 ) using water and air as fluid media, the relative root-mean-square (RMS) deviation of the present predictions from the experimental data is about 5.3%; for the reticulated vitreous carbon (RVC) foams ( k s = 8.5 W m - 1 K - 1 ), the relative RMS deviation is about 7.4%. [ABSTRACT FROM AUTHOR]

Container stacking and reshuffling are important issues in the management of operations in a container terminal. Minimizing the number of reshuffles can increase productivity of the yard cranes and the efficiency of the terminal. In this research, the authors improve the existing static reshuffling model, develop five effective heuristics, and analyze the performance of these algorithms. A discrete-event simulation model is developed to animate the stacking, retrieving, and reshuffling operations and to test the performance of the proposed heuristics and their extended versions in a dynamic environment with arrivals and retrievals of containers. The experimental results for the static problem show that the improved model can solve the reshuffling problem more quickly than the existing model and the proposed extended heuristics are superior to the existing ones. The experimental results for the dynamic problem show that the results of the extended versions of the five proposed heuristics are superior or similar to the best results of the existing heuristics and consume very little time. [ABSTRACT FROM AUTHOR]

Abstract: An extension of a simplified model for the effective thermal conductivity (ETC) of open-cell porous foams, that originally contained only one adjustable parameter, is proposed in this article. The present improved model consists of two adjustable parameters those can be calculated directly from detailed numerical predictions of the ETC under vacuum condition and in presence of a reference fluid with known thermal conductivity ratio (of fluid and solid phases). The performance of present simplified model is evaluated by comparing its estimations with results obtained from detailed numerical simulations, those take into account the true morphology of porous media, as well as predictions obtained from the original simplified model, for the complete range of thermal conductivity ratios, lower than unity ( ). Geometries of porous media are either synthetically generated for idealized regular structures or obtained from high resolution three-dimensional computed tomography-scan images for real foams. The present study clearly demonstrates that the proposed simplified model yields extremely accurate estimation of the ETC for all the investigated structures, as long as the reference thermal conductivity ratio of fluid and solid phases is judiciously chosen. [Copyright &y& Elsevier]

Abstract: In this paper, a comprehensive modeling and parameters extraction method is proposed to describe the current–voltage and power–voltage characteristic of photovoltaic cells. This method is based on data commonly issued by commercial photovoltaic data sheet. By using Lambert W function, the improved model of solar cells is given. Meanwhile, the current–voltage and power–voltage curves of photovoltaic cells are calculated. To extract the model parameters from only three state points at standard test conditions, an optimized approach using iterative method and approximate method is presented. Compared to the popular R p model and experimental data, the proposed method shows excellent agreement between the current–voltages points. It is found that the proposed modeling and parameters extraction method has less error at the maximum power point state. Moreover, the proposed model is more realistic when subjected to ideality factors variations. [Copyright &y& Elsevier]

In this paper, the comparative study of series and parallel solar photovoltaic (SPV) array configurations is carried out to analyze their performance under different shaded working conditions. The different cases of partial shade of the panels have been analyzed. This study has been carried out from the improved model for the simulation work. A novel electronic load method to quickly draw the characteristics and recording the result has been proposed in this paper to validate the developed model. The results have been obtained by writing the mathematical equations in MATLAB- M file. Through M-file programming increased number of modules can be easily studied under different shading patterns. This approach can be extended for finding the different array configurations to attain the higher electrical energy production. [ABSTRACT FROM AUTHOR]

The Robinson equivalent circuit analytical model can be used only in calculating shielding effectiveness of enclosure with the same multi-holes in one wall, but cannot be used in different multi-holes in two walls. According to the practical requirement, this article uses Konefal's and Farhana's characteristic impedance of apertures to improve the equivalent circuit analytical model in different multi-holes in two walls. The improved equivalent circuit analytical model is more useful than Robinson equivalent circuit analytical model. In the article, all kinds of enclosures are simulated by TLM (Transmission-Line Matrix method) to prove that this improved model is feasible in multimode. [ABSTRACT FROM AUTHOR]