Статті в журналах: "Guiding curves"

1

Popa, Gabriel, Ioan Sebesan, Marius Adrian Spiroiu, and Claudiu Nicolae Badea. "Safety against Derailment for Railway Vehicles." Applied Mechanics and Materials 659 (October 2014): 223–30. http://dx.doi.org/10.4028/www.scientific.net/amm.659.223.

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The shock attack occurs at a railway vehicle circulation in a curve in which a discontinuous bend appears, mathematically represented by an angular point. In this point, shock angle produces an abrupt change of direction of the vehicle, respectively a dynamic shock force.The paper presents a mathematical model used to determine the dynamic force shock and its influence on vehicle guiding safety. The study was applied to the tank wagon on bogies for transportation of petroleum products, because such vehicles generally have derailed at circulation in curves in which have occurred accidentally discontinuous bends.It shows that the dynamic force may lead to an unacceptable increase of guiding force Y at leading axle of the vehicle, and therefore to overcome the (Y/Q)lim, which defines the limit of derailment, Q being the load on the attacking wheel.The conclusions indicate constructive measures to be taken to ensure the safety of the vehicle guiding at circulation in curves.

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Krivoshapko, Sergey N., and Svetlana L. Shambina. "The pendulum type surfaces with congruential cross sections." Structural Mechanics of Engineering Constructions and Buildings 17, no. 2 (December 15, 2021): 165–74. http://dx.doi.org/10.22363/1815-5235-2021-17-2-165-174.

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The article discusses new kinematic surfaces that can be attributed to the class of surfaces of congruent cross sections. The surfaces of congruent cross sections were first identified in a separate class by Professor I.I. Kotov. Circular, elliptical and parabolic cylinders are taken as the guiding surfaces, and circles and parabolas are taken as generating plane curves, which can be located in the plane of the generating curve of the guiding cylinder or in a plane parallel to its longitudinal axis. The introduction of a new independent parameter helped to solve the set geometric problems. The analytical formulas are presented in generalized form, so the shape of the flat generatrix curve can be arbitrary. Two types of surfaces are considered: 1) when the local axes of the generating curves remain parallel during their movement; 2) when these axes rotate. The resulting surfaces can be of interest to architects, or can find application in machine-building thin-walled structures or in the study of the trajectories of bodies during their oscillatory-translational motion.

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3

Müller, Dirk, Dana Z. Anderson, Randal J. Grow, Peter D. D. Schwindt, and Eric A. Cornell. "Guiding Neutral Atoms Around Curves with Lithographically Patterned Current-Carrying Wires." Physical Review Letters 83, no. 25 (December 20, 1999): 5194–97. http://dx.doi.org/10.1103/physrevlett.83.5194.

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4

Schutz, Hannah M., Rutger Quispel, Bart J. Veldt, Frank M. M. Smedts, Marie-Paule G. F. Anten, Klaas J. Hoogduin, Pieter Honkoop, et al. "Cumulative sum learning curves guiding multicenter multidisciplinary quality improvement of EUS-guided tissue acquisition of solid pancreatic lesions." Endoscopy International Open 10, no. 04 (April 2022): E549—E557. http://dx.doi.org/10.1055/a-1766-5259.

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Abstract Background and study aims In this study, we evaluated the performance of community hospitals involved in the Dutch quality in endosonography team regarding yield of endoscopic ultrasound (EUS)-guided tissue acquisition (TA) of solid pancreatic lesions using cumulative sum (CUSUM) learning curves. The aims were to assess trends in quality over time and explore potential benefits of CUSUM as a feedback-tool. Patients and methods All consecutive EUS-guided TA procedures for solid pancreatic lesions were registered in five community hospitals between 2015 and 2018. CUSUM learning curves were plotted for overall performance and for performance per center. The American Society of Gastrointestinal Endoscopy-defined key performance indicators, rate of adequate sample (RAS), and diagnostic yield of malignancy (DYM) were used for this purpose. Feedback regarding performance was provided on multiple occasions at regional interest group meetings during the study period. Results A total of 431 EUS-guided TA procedures in 403 patients were included in this study. The overall and per center CUSUM curves for RAS improved over time. CUSUM curves for DYM revealed gradual improvement, reaching the predefined performance target (70 %) overall, and in three of five contributing centers in 2018. Analysis of a sudden downslope development in the CUSUM curve of DYM in one center revealed temporary absence of a senior cytopathologist to have had a temporary negative impact on performance. Conclusions CUSUM-derived learning curves allow for assessment of best practices by comparison among peers in a multidisciplinary multicenter quality improvement initiative and proved to be a valuable and easy-to-interpret means to evaluate EUS performance over time.

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5

Krivoshapko, Sergey N., and Vyacheslav N. Ivanov. "Surfaces of congruent sections on cylinders." Vestnik MGSU, no. 12 (December 2020): 1620–31. http://dx.doi.org/10.22227/1997-0935.2020.12.1620-1631.

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Introduction. The definition of surfaces of congruent sections was first formulated in the work written by I.I. Kotov. These and several other types of surfaces, generated by the motion of a curve, belonged to the class of kinematic surfaces. Such kinematic surfaces as those of plane parallel displacement, surfaces of rotation, Monge surfaces, cyclic surfaces with ge-nerating circles having constant radius, rotative and spiroidal surfaces, helical some helix-shaped surfaces can be included into the class of surfaces that have congruent sections. Materials and methods. Using I.I. Kotov’s methodology, the authors first derived parametrical and vector equations for eight surfaces of congruent pendulum type cross sections of circular, elliptic, and parabolic cylinders and several helix-shaped surfaces. Circles, ellipses, and parabolas, located in the plane of the generating curve of a guiding cylinder or in the planes of a bundle that passes through the longitudinal axis of a cylinder, generate plane curves. Ellipses, analyzed in the article, can be easily converted into circles and this procedure can increase the number of shapes analyzed here. Results. Formulas are provided in the generalized form, so the shape of a plane generating curve can be arbitrary. Some surfaces of congruent sections are determined by two varieties of parametric equations. In one case, the central angle of the guiding cylindrical surface was used as an independent parameter, but in the other case, one of rectangular coordinates of the cylinder’s guiding curve served as an independent parameter. Two types of surfaces are analyzed: 1) when local axes of generating curves remain parallel in motion; 2) when these axes rotate. Conclusions. The analysis of the sources and the results, recommendations and proposals for application of surfaces, having congruent sections, is made with a view to their use in architecture and technology. The list of references has 27 positions, and it shows that the surfaces considered in this paper are being analyzed by architects, engineers, and geometricians both in Russia and abroad.

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Hauser, Vladimír, Olena S. Nozhenko, Kateryna O. Kravchenko, Mária Loulová, Juraj Gerlici, and Tomáš Lack. "Car body and bogie connection modification for track curves passability improvement." MATEC Web of Conferences 157 (2018): 03009. http://dx.doi.org/10.1051/matecconf/201815703009.

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For Tram cars, it is often necessary to operate in cities on strongly curved track, which is followed by an increased effect of the vehicle on the track. Especially, this increased effect occurs in spiral transition curves situated between direct and arc sections or between two arc sections of different radius. In such case, increased guiding forces, creep in the rail - wheel contact, wear and noise generation can be observed. Exactly with the aim to reduce these undesirable effects we designed a tram bogie with steered wheelsets. This paper deals with a modification of its coupling to vehicle body in order to improve vehicle dynamics in transition curves. Proposed innovative construction of this coupling unit is registered by authors under Utility Model Nr. u201609015 and Utility Model Nr. u201703246. Description of the proposed way for a vehicle to pass through curved track with regard to bogie-body coupling and wheelset steering mechanisms with usage of multibody computing software is given in this paper.

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7

Turner, Sean W. D., Wenwei Xu, and Nathalie Voisin. "Inferred inflow forecast horizons guiding reservoir release decisions across the United States." Hydrology and Earth System Sciences 24, no. 3 (March 19, 2020): 1275–91. http://dx.doi.org/10.5194/hess-24-1275-2020.

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Abstract. Medium- to long-range forecasts often guide reservoir release decisions to support water management objectives, including mitigating flood and drought risks. While there is a burgeoning field of science targeted at improving forecast products and associated decision support models, data describing how and when forecasts are applied in practice remain undeveloped. This lack of knowledge may prevent hydrological modelers from developing accurate reservoir release schemes for large-scale, distributed hydrology models that are increasingly used to assess the vulnerabilities of large regions to hydrological stress. We address this issue by estimating seasonally varying, regulated inflow forecast horizons used in the operations of more than 300 dams throughout the conterminous United States (CONUS). For each dam, we take actual forward observed inflows (perfect foresight) as a proxy for forecasted flows available to the operator and then identify for each week of the year the forward horizon that best explains the release decisions taken. Resulting “horizon curves” specify for each dam the inferred inflow forecast horizon as a function of the week of the water year. These curves are analyzed for strength of evidence for contribution of medium- to long-range forecasts in decision making. We use random forest classification to estimate that approximately 80 % of large dams and reservoirs in the US (1553±50 out of 1927 dams with at least 10 Mm3 storage capacity) adopt medium- to long-range inflow forecasts to inform release decisions during at least part of the water year. Long-range forecast horizons (more than 6 weeks ahead) are detected in the operations of reservoirs located in high-elevation regions of the western US, where snowpack information likely guides the release. A simulation exercise conducted on four key western US reservoirs indicates that forecast-informed models of reservoir operations may outperform models that neglect the horizon curve – including during flood and drought conditions.

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Ren, Nai Fei, Lei Jia, and Dian Wang. "Numerical Simulation Analysis on the Temperature Field in Indirect Selective Laser Sintering of 316L." Advanced Materials Research 711 (June 2013): 209–13. http://dx.doi.org/10.4028/www.scientific.net/amr.711.209.

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Using APDL programming language, an appropriate finite element model is created and the moving cyclic loads of Gauss heat source are realized. From the detailed qualitative analysis of the results, the variety laws of temperature field in indirect SLS are obtained. Plot results at different moments, temperature cyclic curves of key points and the curves of depth of fusion and width of fusion on the set paths, are of important guiding significance for subsequent physical experiments.

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9

Wu, Weidong, and Xunnian Yang. "Variational surface design under normal field guidance." Journal of Computational Design and Engineering 2, no. 3 (March 9, 2015): 129–36. http://dx.doi.org/10.1016/j.jcde.2015.03.001.

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Abstract This paper proposes a novel method for shape design of a Bézier surface with given boundary curves. The surface is defined as the minimizer of an extended membrane functional or an extended thin plate functional under the guidance of a specified normal field together with an initial prescribed surface. For given boundary curves and the guiding normal field, the free coefficients of a Bézier surface are obtained by solving a linear system. Unlike previous PDE based surface modeling techniques which construct surfaces just from boundaries, our proposed method can be used to generate smooth and fair surfaces that even follow a specified normal field. Several interesting examples are given to demonstrate the applications of the proposed method in geometric modeling. Highlights Two extended energy functionals are proposed for variational surface modeling. The guiding normal field can be used to control the shapes of the variational surfaces efficiently. The proposed technique can be used for various modeling purposes like editing, hole filling or transition surface design.

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10

Huang, Zhi Lu, and Kuan Min Chen. "Research on the Quantitative Technical Index of Combining Horizontal and Vertical Curves of Expressway." Applied Mechanics and Materials 668-669 (October 2014): 1442–48. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.1442.

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The factors of combining horizontal and vertical curves are analyzed for guiding road design on expressway in practice and ensuring the safety and comfort of vehicle. The influences on drivers' by all kinds of flat vertical combination characteristics are researched. The necessary conditions meeting the horizontal and vertical combination rationality are proposed through the highway and driver characteristics. The identification sight on convex and concave vertical curve under driving at night and overpass are studied based on driver's sight guidance; the indexes of the vertical curve radius and length that my not meet horizontal including vertical combination are raised. Based on road surface drainage, the indexes that may not meet horizontal including vertical combination is proposed from the aspects of longitudinal slope, cross slope drainage and pavement structure. Comprehensive the design of flat vertical combination put forward the quantitative technical indicators that may not meet horizontal including vertical combination.

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11

Yuan, Zhiwang, Zhiping Li, Li Yang, and Yingchun Zhang. "New Waterflooding Characteristic Curves Based on Cumulative Water Injection." Mathematical Problems in Engineering 2020 (April 27, 2020): 1–12. http://dx.doi.org/10.1155/2020/7415236.

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When a conventional waterflooding characteristic curve (WFCC) is used to predict cumulative oil production at a certain stage, the curve depends on the predicted water cut at the predicted cutoff point, but forecasting the water cut is very difficult. For the reservoirs whose pressure is maintained by water injection, based on the water-oil phase seepage theory and the principle of material balance, the equations relating the cumulative oil production and cumulative water injection at the moderately high water cut stage and the ultrahigh water cut stage are derived and termed the Yuan-A and Yuan-B curves, respectively. And then, we theoretically analyze the causes of the prediction errors of cumulative oil production by the Yuan-A curve and give suggestions. In addition, at the ultrahigh water cut stage, the Yuan-B water cut prediction formula is established, which can predict the water cut according to the cumulative water injection and solve the difficult problem of water cut prediction. The application results show Yuan-A and Yuan-B curves are applied to forecast oil production based on cumulative water injection data obtained by the balance of injection and production, avoiding reliance on the water cut forecast and solving the problems of predicting the cumulative oil production of producers or reservoirs that have not yet shown the decline rule. Furthermore, the formulas are simple and convenient, providing certain guiding significance for the prediction of cumulative oil production and water cut for the same reservoir types.

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12

Karygiannis, M. N., Z. Szatmary, P. A. Claudino, and E. Houdart. "Facial Vein Catheterization for Transvenous Embolization of the Cavernous Sinus." Interventional Neuroradiology 12, no. 1 (March 2006): 25–30. http://dx.doi.org/10.1177/159101990601200105.

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We describe three cases of transvenous embolization of arteriovenous fistulas of the cavernous sinus, achieved through the facial vein approach. The facial vein was catheterized from a jugular vein access. This cervical approach offered good stability to the guiding catheter that permitted us to negotiate difficult curves of the facial vein and to recanalize venous thrombosis in one case.

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13

NOCOŃ, Łukasz, and Konrad STEFAŃSKI. "Impact of Controller Performance on the Process of Guiding an Armour-Piercing Missile onto a Ground-Based Target." Problems of Mechatronics Armament Aviation Safety Engineering 7, no. 4 (December 30, 2016): 67–84. http://dx.doi.org/10.5604/01.3001.0009.5020.

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This work presents an analysis of guiding an anti-tank missile (ATGM) onto a ground-based target. The concept presented here is the feasibility of bypassing obstacles in the path of an ATGM when the obstacle coordinates are known prior to firing the ATGM weapon. The ATGM contemplated here uses a homing algorithm to calculate the stages of the ATGM flight path with the use of polynomial curves (including third-degree polynomial curves). The start and end coordinates of the polynomial curves are determined by the position of the obstacle(s) along the flight path. A method is presented for calculating the factors of subsequent flight path stages, along with a method of equating the ATGM kinematics and dynamics. A comparison is made between the operating efficiency of various configurations of a traditional proportional integral derivative (PID) controller, and at various gain factor values of the PID controller stages. The applied mathematical model of the ATGM are used in a series of numerical simulations for different take-off and in-flight conditions of the projectile. The simulation results are presented in a graphical form.

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Ghimire, Narayan, and Hemchandra Chaulagain. "Seismic Fragility Analysis of Institutional Building of Pokhara University." Himalayan Journal of Applied Science and Engineering 1, no. 1 (December 18, 2020): 31–39. http://dx.doi.org/10.3126/hijase.v1i1.33539.

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Fragility curves are derived from fragility function that indicates the probability of damage of structure due to earthquake as a function of ground motion parameter. It helps to predict the level of structural damage and consequently reduce the seismic risk in specific ground motion. In this scenario, this study is focused on the construction of fragility curve of institutional reinforced concrete (RC) building of Pokhara University. For this, the building of School of Health and Allied Science (SHAS) is considered as a guiding case study. For the numerical analysis, the study building blocks are modelled in finite element-based software. The non-linear static and linear dynamic analyses are employed for numerical analysis. In dynamic analysis, building models are subjected to the synthetic accelerograms of the 2015 Gorkha earthquake. Based on the analyses, the analytical fragility curves are plotted in terms of probability of failure at every 0.1 g interval of peak ground acceleration (PGA) with log normal distribution. Finally, the results are highlighted for different seismic performance level in buildings: slight damage, moderate damage, extensive damage and complete damage for the earthquake of 475 years return period.

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Chen, Wangang, Yu Yang, Hansen Sun, Chengwei Zhang, Qin Wen, and Yanyan Li. "Solution and type curves for the seepage model of the water-bearing coalbed with leakage recharge." Earth Sciences Research Journal 21, no. 1 (January 1, 2017): 17. http://dx.doi.org/10.15446/esrj.v21n1.63003.

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To analyze the effects of the leakage recharge of the aquifer on the initial dewatering of coalbed methane wells, the mathematical seepage model of water in the coalbed considering the aquifer leakage was established by using the leakage coefficient according to the unsteady seepage theory. The model was solved after Laplace transform and the Stehfest numerical reverse inversion was used to obtain the solution in right space. Then, the log-log type curves of pressure and pressure derivative were created with new combinations of parameters. Based on the natural seepage mechanism, the influence of aquifer leakage on curve shape was judged. It is found that the radial flow ends earlier as the leakage coefficient increases. Moreover, it was proposed to obtain reservoir permeability, skin factor, and leakage coefficient by using type curve matching. The type curves are useful for quantitatively evaluating the level of leakage, thereby guiding the adjustment of the following production system for CBM wells. Curvas de solución y tipo para el modelo de filtración de capas carboníferas acuíferas con recarga de fugasResumenEste estudio estableció el modelo matemático de filtración de agua en una capa carbonífera al estimar la salida acuífera con el uso del coeficiente de fuga, de acuerdo con la teoría de filtración inestable, para analizar los efectos en la recarga de pérdida de fluidos de un acuífero en el drenado inicial para pozos de gas metano. El modelo se resolvió tras usar la transformación Laplace y la inversión numérica Stehfest para encontrar la respuesta en el lugar indicado. Luego, se creó la representación algorítmica de la presión y la presión derivativa con nuevas combinaciones de parámetros. Se evaluó la influencia de la pérdida de fluido del acuífero en la forma de la curva con base al mecanismo físico de filtración. Se estableció que el flujo radial finaliza antes de que el coeficiente de pérdida de fluido se incremente. Además, se propone el uso de la curva tipo correspondiente para obtener la permeabilidad del reservorio, el factor de daño y el coeficiente de pérdida de fluido. Las curvas tipo son útiles para evaluar cuantitativamente el nivel de la pérdida de fluido, y de esta manera guiar el ajuste de un sistema de producción consecuente para pozos de gas metano de carbón.

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Alves, Roberto Dutra, Gilson de F. N. Gitirana, and Sai K. Vanapalli. "Evaluation of prediction models applied to the soil-water characteristic curve of ideal materials." E3S Web of Conferences 195 (2020): 02024. http://dx.doi.org/10.1051/e3sconf/202019502024.

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The development of theoretical and semi-empirical models to study capillary mechanisms and predict the soil-water characteristic curve (SWCC) generally requires the idealization of pore space and pore water, considering simplifying hypotheses. The study of ideal materials comprised of particles with controlled shape and size allows the evaluation of such simplifying hypotheses and the subsequent generalization to actual soils. In this paper, four theoretical and semi-empirical models for the prediction of the SWCC are applied to the prediction of artificial materials comprised of spherical particles. Nineteen grain-size distribution curves, with varying coefficients of uniformity are considered. The dataset is comprised of materials previously published and additional tests carried out by the authors, under highly controlled conditions. The analyses allowed the evaluation of the effect of grain-size distribution curve and shape of the particles. The limitations and advantages of each prediction model was investigated, and a detailed comparison is presented, guiding future implementations of improved models.

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Wang, Yan, Xinyu Bao, Song Zhang, Lin Yang, Guoli Liu, Yimin Yang, Xuwen Li, et al. "Fetal growth prediction: Establishing fetal growth prediction curves in the second trimester." Technology and Health Care 29 (March 25, 2021): 345–50. http://dx.doi.org/10.3233/thc-218032.

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BACKGROUND: Monitoring fetal weight during pregnancy has a guiding role in prenatal care. OBJECTIVE: To establish a personalized fetal growth curve for effectively monitoring fetal growth during pregnancy. METHODS: (1) This study retrospectively analyzed the birth weight database of 2,474 singleton newborns delivered normally at term. The personalized fetal growth curve model was formed by combining the estimating birth weight of newborns with the proportional weight formula. (2) Multiple linear stepwise regression method was used to estimate the birth weight of newborns. RESULTS: (1) Delivery gestational age, weight at first visit, maternal height, pre-pregnancy body mass index, fetal sex, parity had significant effects on birth weight. Based on these parameters, the formula for calculating term optimal weight was obtained (R2= 22.8%, P< 0.001). (2) The personalized fetal growth curve was obtained according to the epidemiological factors input model of each pregnant woman. CONCLUSIONS: A model of personalized fetal growth curve can be established, and be used to evaluate fetal growth and development through estimated fetal weight monitoring.

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Hussein, Aya J., Sofyan A. Taya, D. Vigneswaran, R. Udiayakumar, Anurag Upadhyay, Toni Anwar, and Iraj S. Amiri. "Universal dispersion curves of a planar waveguide with an exponential graded-index guiding layer and a nonlinear cladding." Results in Physics 20 (January 2021): 103734. http://dx.doi.org/10.1016/j.rinp.2020.103734.

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Stamou, Anastasios I. "Verification and application of a mathematical model for the assessment of the effect of guiding walls on the hydraulic efficiency of chlorination tanks." Journal of Hydroinformatics 4, no. 4 (October 1, 2002): 245–54. http://dx.doi.org/10.2166/hydro.2002.0024.

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A mathematical model is applied to the tank of Kipseli in Athens, Greece, which is used for storage, balancing and emergency chlorination. A Flow-Through Curve (FTC) experiment is performed for the initial geometry of the tank. The shape and the characteristics of the FTC show a very poor hydraulic efficiency, with extensive short-circuiting, intense mixing and low detention times. To improve the hydraulic efficiency of the tank the use of four alternative arrangements of guiding walls is examined by the model. Prior to its application, the model is verified by comparing the predicted FTC with the experimental. A satisfactory agreement is observed between the calculated and the experimental curves. Then the model is applied to calculate the flow field and the FTC for the four arrangements. Calculations are compared and the arrangement which shows the highest hydraulic efficiency is proposed for construction.

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Wang, Shih-Ming, Chun-Yi Lee, Hariyanto Gunawan, and Chin-Cheng Yeh. "An Accuracy-Efficiency-Power Consumption Hybrid Optimization Method for CNC Milling Process." Applied Sciences 9, no. 7 (April 10, 2019): 1495. http://dx.doi.org/10.3390/app9071495.

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This study proposes a hybrid optimization method which can help users to find optimal cutting parameters which will provide better efficiency and lower power consumption for a milling process. Empirical models including performance-power consumption characteristic curves of servo motors were built, and an optimization algorithm adopting the empirical models with procedure guiding function was developed. The empirical models were built based on the measurements from planned machining experiments with different combination of machining parameters including spindle speed, feedrate, and chip load, etc. After integrating the models and algorithm, an optimization system with human machine interface, which has procedure guiding function, was developed. The system can recommend optimal machining parameters for a milling process for shorter machining time and lower electricity costs based on the original machining parameters. Finally, cutting experiments were conducted to verify the proposed system, and the results showed that the proposed method can effectively enhance efficiency by 42.06% and save 34.74% in machining costs through reducing machining time and electrical power consumption.

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Zhang, Yunkai, Fei Liu, Yuhan Bao, and Haiyan Yuan. "Research on Dynamic Stress–Strain Change Rules of Rubber-Particle-Mixed Sand." Coatings 12, no. 10 (October 4, 2022): 1470. http://dx.doi.org/10.3390/coatings12101470.

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We conducted GDS dynamic triaxial tests to study the change rules of the hysteresis curve morphology, axial strain, dynamic elastic modulus, and damping ratio of waste tire rubber-mixed sand-based subgrade model samples with different rubber particle sizes, rubber mixing amounts, and loading times. The research revealed the developmental rule of the hysteresis curves of waste tire rubber-mixed-sand samples under cyclic loading. From the analyses and comparison of the dynamic stress–strain change rules of rubber-particle-mixed-sand samples under different test conditions, it was concluded that the dynamic elastic modulus and shear stiffness of rubber-mixed-sand samples were smaller than those of pure sand samples under cyclic loading while their damping ratios were greater than that of pure sand samples, promoting vibration resistance and reduction to a larger extent. Therefore, this conclusion is of guiding significance for engineering practice.

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Cao, Shuting, and Haiyuan Liu. "Effectiveness Analysis of Edmodo-Based Blended English Learning Mode." International Journal of Emerging Technologies in Learning (iJET) 14, no. 18 (September 30, 2019): 64. http://dx.doi.org/10.3991/ijet.v14i18.11184.

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This paper attempts to overcome the defects of traditional English learning mode, including poor real-time communication ability, heavy reliance on individual self-discipline, and undesirable learning effect. Drawing on the theories of English learning motivation, the author analyzed the relationship between learning motiva-tion and learning behavior in light of the Edmodo-based blended English learning mode, and put forward the English learning persistence rate formula, thus reveal-ing the correlations between learning cost, objective external learning environ-ment, learning motivation, and learning persistent rate. In addition, the English courses were made more pertinent according to the Ebbinghaus forgetting curve. The course test data were fitted and weighted, outputting intuitive curves on learning effect. The research results show that the Edmodo-based blended Eng-lish learning mode has a significant learning effect, and a guiding significance for English learning and English teaching reform.

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Gu, Zhenghan, Yi Zhang, Yifeng Wu, Feng Zhang, Lv Tang, and Jianguo Mo. "Study on the Operation Optimization Dispatching Strategy of Small and Medium-sized Pumped Storage Power Station." Journal of Physics: Conference Series 2254, no. 1 (April 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2254/1/012014.

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Abstract This paper uses equivalent substitution method and random production simulation method to calculate the static efficiency of daily operation of small and medium-sized pumped storage power stations, maximize the static efficiency under energy storage constraints, and obtain the daily output operation scheduling plan of pumped storage power station. Their utility and effectiveness are demonstrated by using multiple load curves including summer peak load and holiday load and applying the calculation results to practical scheduling operations. This method for the same type of pumped storage power station, has a general practical and guiding value.

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Dautov, Rafail Z., and Evgenii M. Karchevskii. "Numerical Modeling of Optical Fibers Using the Finite Element Method and an Exact Non-reflecting Boundary Condition." Computational Methods in Applied Mathematics 18, no. 4 (October 1, 2018): 581–601. http://dx.doi.org/10.1515/cmam-2017-0049.

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AbstractThe original problem for eigenwaves of weakly guiding optical fibers formulated on the plane is reduced to a convenient for numerical solution linear parametric eigenvalue problem posed in a disk. The study of the solvability of this problem is based on the spectral theory of compact self-adjoint operators. Properties of dispersion curves are investigated for the new formulation of the problem. An efficient numerical method based on FEM approximations is developed. Error estimates for approximate solutions are derived. The rate of convergence for the presented algorithm is investigated numerically.

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Krenning, Boudewijn J., Tamas Szili-Torok, Marco M. Voormolen, Dominic A. M. J. Theuns, Luc J. Jordaens, Charles T. Lancée, Nico de Jong, Anton F. W. van der Steen, Folkert J. Ten Cate, and Jos R. T. C. Roelandt. "Guiding and optimization of resynchronization therapy with dynamic three-dimensional echocardiography and segmental volume-time curves: a feasibility study." European Journal of Heart Failure 6, no. 5 (August 2004): 619–25. http://dx.doi.org/10.1016/j.ejheart.2004.05.005.

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Jiao, Fangtong, Zhigang Du, Yiik Diew Wong, Jialin Mei, and Feng Sun. "Design and evaluation of visual guiding facilities along urban road tunnel horizontal curves based on vision and speed perception." Tunnelling and Underground Space Technology 133 (March 2023): 104937. http://dx.doi.org/10.1016/j.tust.2022.104937.

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27

Terrell, Dirk. "Mass Ratio and Spot Parameter Estimation from Eclipsing Binary Star Light Curves." Galaxies 10, no. 1 (January 5, 2022): 8. http://dx.doi.org/10.3390/galaxies10010008.

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Анотація:

Eclipsing binary stars have a rich history of contributing to the field of stellar astrophysics. Most of the available information on the fundamental properties of stars has come from the analysis of observations of binaries. The availability of powerful computers and sophisticated codes that apply physical models has resulted in determinations of masses and radii of sufficient accuracy to provide critical tests of theories of stellar structure and evolution. Despite their sophistication, these codes still require the guiding hand of trained scientists to extract reliable information. The computer code will produce results, but it is still imperative for the analyst to ensure that those results make astrophysical sense, and to ascertain their reliability. Care must be taken to ensure that we are asking the codes for parameters for which there is information in the data. The analysis of synthetic observations with simulated observational errors of typical size can provide valuable insight to the analysis process because the parameters used to generate the observations are known. Such observations are herein analyzed to guide the process of determining mass ratios and spot parameters from eclipsing binary light curves. The goal of this paper is to illustrate some of the subtleties that need to be recognized and treated properly when analyzing binary star data.

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Chigora, Farai, Emmanuel Mutambara, Joram Ndlovu, Joe Muzurura, and Promise Zvavahera. "Towards Establishing Zimbabwe Tourism Destination Brand Equity Variables through Sustainable Community Involvement." December 2020, no. 9(5) (December 31, 2020): 1094–110. http://dx.doi.org/10.46222/ajhtl.19770720-71.

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The study investigated the contribution of local communities to Zimbabwe tourism destination brand equity through sustainable tourism practices, with a view of developing a model. A comparative investigation of two popular resorts in Zimbabwe which are Victoria Falls and Domboshava Curves was carried out. A sequential mixed method was used to get research data. Results from in-depth interviews showed that sustainable brand equity through community involvement can be developed from the following: maintaining culture; attractive traditional villages; traditional music and dances; unique traditional dressing; provision of indigenous food and drinks; guiding tourists and provision of transport and accommodation. A further survey then produced variables that were used to construct a community based sustainable brand equity model for the study. These variables were then grouped into two that is, household activities and service provision. Household activities included: providing indigenous food and drinks; attractive homesteads; and unique dress code. The service provision was discovered as guiding tourists in their activities and provision of transport. The study then recommended local eco-responsibility, destination manager partner with locals, cultural tourism focus and customisation of sustainable tourism.

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Meng, Wen Yuan, Jia Qing Li, Ying Kui Guo, Guan Chao Xu, and Jun Wei Guo. "The Impact on the Pier of Shaped Charge Ice-Breaking and Numerical Simulation Analysis." Applied Mechanics and Materials 501-504 (January 2014): 1883–87. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1883.

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In the process of shaped charge ice-breaking , the response of piers is great under the impact of air, ice, water etc, and relates to integral security of the bridge. For the impact on the pier with burst points of the different distances is simulated by ANSYS / DYNA software, summarizes the impact on the pier of shaped charge ice-breaking, and obtains the maximum stress curves of the pier at different distances. Simultaneously, the paper analyses critical damaging- model of the C30 reinforced concrete piers in detail. The conclusion has a major role in guiding when shaped charge ice-breaking appears.

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30

Zhong, Wantong. "Portfolio Construction in Terms of Bitcoin, S&P 500, Gold Futures and American 10-year National Debt." BCP Business & Management 35 (December 31, 2022): 675–82. http://dx.doi.org/10.54691/bcpbm.v35i.3369.

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Contemporarily, the financial sector occupies a vital part of the world, and asset allocation in it is the top priority. Portfolio construction is the main procedure of asset allocation. In order to gain better application of asset allocation, this paper selects two representative models from the most classic asset allocation models (i.e., Index model and Markowitz model), as well as processes and analyzes them with actual data and targets to obtain real model results. Specifically, this article compares the curves under five different constraints from two models. According to the analysis, the Index model has better performance and fit well in this case, while curves of the Markowitz model have more outliers, which may cause bad impacts in real cases. Based on the evaluations, the pros and cons of the two models and the different conditions for adaptation can be compared to a certain extent. These results shed light on guiding further exploration of portfolio designs.

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Shi, Yan, Miao Li, Weihua Ma, and Kang Chen. "Dynamic of Friction Coupling Independently Rotating Wheels for High Speed." Shock and Vibration 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/7456598.

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A new lateral coupling structure with independently rotating wheels (IRW) is proposed, and longitudinal creepage is obtained by replacing the gear pair with the friction pair to synchronize the rotation speed of left and right wheels. The auxiliary wheelset made up of two friction wheels can be placed either under the primary suspension or on the frame. Vehicles dynamics models with three different kinds of bogies are developed, including friction coupling bogie with independently rotating wheels (FCIRW-bogie), bogie with independently rotating wheels (IRW-bogie), and bogie with rigid wheelsets, and their guiding and resetting capability when negotiating large-radius curves are compared and analyzed. Results show that FCIRW has the advantages of both IRW and rigid wheelset. On the straight track, FCIRW has sufficient wheel-rail longitudinal creep force to assist the reset; its critical speed is much higher than that of the rigid wheelset. On the curved track, the whole vehicle wear power of FCIRW-bogie vehicle is about 2/3 of the rigid axle level.

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Wu, Shi, Yun Tong Jia, and Da Qu. "The Nonlinear Characteristic of Vibration Signal in Milling Flutter Process." Applied Mechanics and Materials 274 (January 2013): 128–31. http://dx.doi.org/10.4028/www.scientific.net/amm.274.128.

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In order to analysis the nonlinear characteristics of vibration signal in the milling chatter process, this article uses Lyapunov Exponent and Approximate Entropy to analysis vibration signal of stable milling, vibration signal of chatter development and vibration signal of chatter in varied cutting-depth milling process. Plot the relationship curves of milling parameters with Lyapunov Exponent and Approximate Entropy respectively. The results showed that vibration signal had strong chaos characteristics when the milling chatter developed and occurred, and chaos characteristics of the vibration signal can be regarded as an effective method to identify the development and occurrence of chatter, and it also has guiding function for choosing milling parameter.

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Kim, Sun, and Taeseok Ki. "Variable Guide Vane Scheduling Method Based on the Kinematic Model and Dual Schedule Curves." Applied Sciences 10, no. 19 (September 23, 2020): 6643. http://dx.doi.org/10.3390/app10196643.

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The variable guide vanes (VGV) of gas turbine engines are commonly utilized to expand operating range and to improve efficiency of the compressor. Guiding air flow using the VGVs in the compressor prevents aerodynamic instability by making proper incidence angle to the blades. In this study, we dealt with rig-type three-stages VGVs for developed engine tests. The three link mechanism of VGVs are linked to each other with two hydraulic actuators, and inevitably, induced hysteresis exists between vane rotations and actuators strokes, due to links with non-fully constrained degree of freedoms for easy installation and instrumentation, as well. Therefore, the adjustment of each VGVs link mechanism is required to satisfy vane angle demands. To adjust coupled three-stages VGVs link mechanism, an analytical VGV-link kinematic model was derived, and effects of two adjusting parameters (lengths of bell cranks and vertical links) were discovered. Lastly, we obtained two vane angle schedule curves from the experiments according to link moving directions, and applied them to the engine controller to minimize hysteresis of the variable inlet guide vane (VIGV). The proposed VGV adjusting and controlling method can be simply applied to the pre-designed or pre-manufactured VGVs system without mechanical compensation or additional cost.

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34

Garnier, Lucas, Arthur Doliveira, Fabrice Mahé, Etienne Gaviot, and Bruno Bêche. "Temporal derivation operator applied on the historic and school case of slab waveguides families eigenvalue equations: another method for computation of variational expressions." European Physical Journal Applied Physics 87, no. 1 (July 2019): 10501. http://dx.doi.org/10.1051/epjap/2019190092.

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Starting from the well-known and historic eigenvalue equations describing the behavior of 3-layer and 4-layer slab waveguides, this paper presents another specific analytical framework providing time-laws of evolution of the effective propagation constant associated to such structures, in case of temporal variation of its various geometrical features. So as to develop such kind of time-propagator formulation and related principles, a temporal derivation operator is applied on the studied school case equations, considering then time varying values of all the geometrical characteristics together with the effective propagation constant. Relevant calculations are performed on three different cases. For example, we first investigate the variation of the height of the guiding layer for the family of 3-layer slab waveguides: then, considering the 4-layer slab waveguide's family, we successively address the variation of its guiding layer and of its first upper cladding. As regards the family of 4-layer waveguides, calculations are performed for two different families of guided modes and light cones. Such another approach yields rigorous new generic analytical relations, easily implementable and highly valuable to obtain and trace all the family of dispersion curves by one single time-integration and one way.

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35

Singh, Vivek, B. Prasad, and S. P. Ojha. "Modal analysis and dispersion curves of an annular waveguide having a guiding-region cross section bounded by two lemniscates of Bernoulli." Microwave and Optical Technology Letters 28, no. 1 (2000): 75–78. http://dx.doi.org/10.1002/1098-2760(20010105)28:1<75::aid-mop21>3.0.co;2-4.

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36

Shi, Pei Cheng, and Wen Chen Xie. "The Vibration Analysis of Five Degrees of Freedom Man-Vehicle-Road Coupled Model." Advanced Materials Research 765-767 (September 2013): 361–65. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.361.

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The 5-DOF man-vehicle-road coupled vibration model is established by the relationship among three interactions of man-vehicle-road and the vibration differential equation of the 5-DOF man-vehicle-road model is obtained by Newtons method. The mathematical model is conversed into the derived simulation model based on MATLAB/SIMULINK software. The vibration characteristics of the 5-DOF couple model are analyzed by the excitations of ride speed and random road surface roughness time series since the corresponding parameters have been set. The paper demonstrates the acceleration curves and their response characteristics of the bodywork and man-chair system. The study results have a guiding significance and reference value to analyze the vehicle ride comfort.

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37

Xu, Wenbin, Zhihui Liu, Jie Liu, and Yongfei Yang. "New Understanding of Transient Pressure Response in the Transition Zone of Oil-Water and Gas-Water Systems." Geofluids 2018 (September 17, 2018): 1–15. http://dx.doi.org/10.1155/2018/1210950.

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Well test analysis requires a preselected model, which relies on the context input and the diagnostic result through the pressure logarithmic derivative curve. Transient pressure outer boundary response heavily impacts on the selection of such a model. Traditional boundary-type curves used for such diagnostic purpose are only suitable for single-phase flow in a homogeneous reservoir, while practical situations are often much more complicated. This is particularly true when transient pressure is derived during the field development phase, for example, from permanent down-hole gauge (PDG), where outer boundary condition such as an active aquifer with a transition zone above it plays a big role in dominating the late time pressure response. In this case, capillary pressure and the total mobility in the transition zone have significant effect on the pressure response. This effect is distinctly different for oil-water system and gas water system, which will result in the pressure logarithmic derivatives remarkably different from the traditional boundary-type curves. This paper presents study results derived through theoretical and numerical well testing approaches to solve this problem. The outcome of this study can help in understanding the reservoir behavior and guiding the management of mature field. According to the theoretical development by Thompson, a new approach was derived according to Darcy’s law, which shows that pressure response in the transition zone is a function of total effective mobility. For oil-water system, the total effective mobility increases with an increase in the radius of transition zone, while for gas-water system, the effect is opposite.

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38

Xu, Liqi, Xiaoli Xu, Yiming Sun, and Tianci Lu. "Evaluation of Rock Brittleness Based on Complete Stress–Strain Curve." Mathematics 10, no. 23 (November 26, 2022): 4470. http://dx.doi.org/10.3390/math10234470.

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As a basic mechanical property of rocks, brittleness is closely related to the drillability, wellbore stability, and rockburst characteristics of reservoir rocks. Accurate evaluation of rock brittleness is of great significance for guiding oil and gas production and reservoir reconstruction. This paper systematically introduced the commonly used brittleness evaluation methods based on the stress–strain curve and analyzed their theoretical background and mathematical models. Combined with practical engineering application, the characterization effect of commonly used brittleness indexes in various rock samples is verified and optimized, and it is obtained that the brittleness index (B17 in this paper), based on the stress–strain curve and considering energy conversion, has the best characterization result for rock brittleness, which has good differentiation for different rock samples. At the same time, considering that the stress–strain curve under high confining pressure may result in a significant yield plateau phenomenon before and after the peak strength, the endpoint of the plastic yield plateau is used to replace the peak point as the starting point for the drop of bearing capacity. The revised brittleness index is consistent with the changing trend of the original curve, which verifies the reliability of the model. Finally, the method for characterizing the brittleness of Class II curves is supplemented, and the combined brittleness index of rock is established, which verifies the rationality and correctness of the index and provide a more general evaluation method for rock brittleness in engineering.

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Zhang, Qiang, Ding Li, Juan Wen, Kai Jia Luo, and Zhi Chen. "Design and Experimental Simulation Analysis of a Kind of Prestressed Cementing Drillable Anchor." Applied Mechanics and Materials 628 (September 2014): 163–66. http://dx.doi.org/10.4028/www.scientific.net/amm.628.163.

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Cementing anchor plays an important role in prestressed cementing technology of heavy oil thermal recovery. For there are many problems of other anchor: undrillable structure, not to be satisfied the requirements of continue drilling or deepening old well, the authors have designed a drillable anchor. By the way of using finite element analysis, them obtained that the initial angle 38-40° was the best angle for eating into the formation; verified the intensity of anchor-pin system. Through cycling test, them verified the reliability of the anchor; obtained the curves of flow coefficient and the press differential with different nozzle. The analysis and experimental results is very important in guiding significance to optimize the design of the anchor and prestressed cementing operation.

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40

Wong, Lester P. K., Prudence W. H. Cheung, and Jason P. Y. Cheung. "Supine correction index as a predictor for brace outcome in adolescent idiopathic scoliosis." Bone & Joint Journal 104-B, no. 4 (April 1, 2022): 495–503. http://dx.doi.org/10.1302/0301-620x.104b4.bjj-2021-1220.r1.

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Aims The aim of this study was to assess the ability of morphological spinal parameters to predict the outcome of bracing in patients with adolescent idiopathic scoliosis (AIS) and to establish a novel supine correction index (SCI) for guiding bracing treatment. Methods Patients with AIS to be treated by bracing were prospectively recruited between December 2016 and 2018, and were followed until brace removal. In all, 207 patients with a mean age at recruitment of 12.8 years (SD 1.2) were enrolled. Cobb angles, supine flexibility, and the rate of in-brace correction were measured and used to predict curve progression at the end of follow-up. The SCI was defined as the ratio between correction rate and flexibility. Receiver operating characteristic (ROC) curve analysis was carried out to assess the optimal thresholds for flexibility, correction rate, and SCI in predicting a higher risk of progression, defined by a change in Cobb angle of ≥ 5° or the need for surgery. Results The baseline Cobb angles were similar (p = 0.374) in patients whose curves progressed (32.7° (SD 10.7)) and in those whose curves remained stable (31.4° (SD 6.1)). High supine flexibility (odds ratio (OR) 0.947 (95% CI 0.910 to 0.984); p = 0.006) and correction rate (OR 0.926 (95% CI 0.890 to 0.964); p < 0.001) predicted a lower incidence of progression after adjusting for Cobb angle, Risser sign, curve type, menarche status, distal radius and ulna grading, and brace compliance. ROC curve analysis identified a cut-off of 18.1% for flexibility (sensitivity 0.682, specificity 0.704) and a cut-off of 28.8% for correction rate (sensitivity 0.773, specificity 0.691) in predicting a lower risk of curve progression. A SCI of greater than 1.21 predicted a lower risk of progression (OR 0.4 (95% CI 0.251 to 0.955); sensitivity 0.583, specificity 0.591; p = 0.036). Conclusion A higher supine flexibility (18.1%) and correction rate (28.8%), and a SCI of greater than 1.21 predicted a lower risk of progression. These novel parameters can be used as a guide to optimize the outcome of bracing. Cite this article: Bone Joint J 2022;104-B(4):495–503.

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Li, Xiaofeng, and Zhixiang Yin. "A Time-Dependent Creep Constitutive Model of Deep Surrounding Rock under Temperature-Stress Coupling." Mathematical Problems in Engineering 2021 (June 14, 2021): 1–11. http://dx.doi.org/10.1155/2021/9938869.

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In order to study the creep behavior of the surrounding rock of Hengda coal mine in Fuxin under different temperatures, the triaxial creep test of sandstone is carried out by the MTS815.02 test system. The relationship between damage variables and temperature is constructed based on the Weibull distribution of the meso-probability voxel intensity. Aiming at the nonlinear characteristics of rock creep, a nonlinear viscous pot element and a nonlinear spring element are proposed. The two linear viscous pot elements and one linear spring element in the Nishihara model can be replaced separately. Thus, an unsteady parameter creep model is established. The comparison between the Nishihara model curve and the model and the experimental curves in this article has been added to the article. Furthermore, the superiority of this model can be proved. The results show that the established variable-time aging creep model not only can describe the rock attenuation creep and stable creep deformation characteristics but also can make up for the shortcomings of the traditional creep model that cannot describe the accelerated creep characteristics. Moreover, it predicts the development law of creep deformation well. The model is in good agreement with the test curve, which shows the correctness and rationality of the model. It has guiding significance for actual engineering support and prediction of long-term deformation of surrounding rock.

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42

Do, Ha T. T., Heidi C. Zimmer, Jerome K. Vanclay, John C. Grant, Bon N. Trinh, Hoang H. Nguyen, and J. Doland Nichols. "Site form classification—a practical tool for guiding site-specific tropical forest landscape restoration and management." Forestry: An International Journal of Forest Research 95, no. 2 (October 19, 2021): 261–73. http://dx.doi.org/10.1093/forestry/cpab046.

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Abstract Reliable estimates of forest productivity at the site scale can guide site-specific forest management. However, the best methods to evaluate productivity of natural forest sites, and in particular secondary natural forests, remain undefined. In this study we: (1) applied an indirect method for estimation of the potential productivity of a forest site (‘site form’) in Dong Nai Biosphere Reserve. In addition, we: (2a) investigated the influence of a range of environmental conditions on site form, (2b) built models to estimate site form from the corresponding environmental variables and (3) generated site form maps for the region. We found that Michaelis–Menten models provided the most consistent representation of tree height–diameter relationships, with reliable anamorphic curves at both plot-scale (50 m × 20 m) and multiplot-scales. Predicted tree height at 25-cm diameter (H25) was selected as the best indicator for site form as 25 cm was both a tree size, which was common in the forests, and for which height could be accurately predicted. H25 was significantly correlated with site environmental conditions, with the dominant influences being factors related to water availability. We generated site form maps for Dong Nai province based on the relationship between known environmental variables and H25. We conclude that maps such as these could have broad application in guiding tropical forest restoration measures elsewhere, particularly where there is limited knowledge of tree ages and species.

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Chen, Minxia, Yan Yang, Chengbin He, Litian Chen, and Jianmin Cheng. "Nomogram based on prognostic nutrition index and Chest CT imaging signs predicts lymph node metastasis in NSCLC patients." Journal of X-Ray Science and Technology 30, no. 3 (April 15, 2022): 599–612. http://dx.doi.org/10.3233/xst-211080.

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OBJECTIVE: To establish and validate a model capable of predicting lymph node metastasis (LNM) of non-small cell lung cancer (NSCLC) patients. METHODS: Preoperative clinical and CT imaging data on patients with NSCLC undergoing surgery were retrospectively analyzed. A model was developed using a training cohort of 290 patients. The univariate analysis followed by dichotomous logistic regression was performed to estimate different risk factors of lymph node metastasis, and a nomogram was constructed. Using another testing cohort of 120 patients, the performance of the nomogram was validated using several evaluation methods and indices and evaluated including via the area under the curve (AUC), calibration curve, Hosmer-Lemeshow test and decision curve analysis (DCA). RESULTS: CT-based imaging signs were important independent risk factors for lymph node metastasis in NSCLC patients. The possible risk factors also included four other independent risk factors through dichotomous logistic regression, i.e., age, SIRI, PNI and CEA, which were filtered and included in the nomogram. Nomogram yields AUC values of 0.828 [95% confidence interval (CI): 0.778–0.877] in the training cohort and 0.816 (95% CI: 0.737–0.895) in the validation cohort, respectively. The calibration curves showed high agreement in both the training and validation cohorts. At the threshold probability of 0–0.8, the nomogram increases the net outcomes compared to the treat-none and treat-all lines in the decision curve. CONCLUSIONS: The nomogram based on the PNI and CT images signs holds promise as a novel and accurate tool for predicting the LNM in NSCLC patients and guiding intraoperative lymph node dissection.

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Li, Dong Tao, Li Xin Xu, Yuan Yuan Sun, Qiu Rui Jia, and Jing Long Yan. "Study on Energy Distribution of Single-Hole Blasting Vibration Signal Based on Wavelet Packet Transform." Applied Mechanics and Materials 321-324 (June 2013): 1284–89. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.1284.

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It is conducive to reducedamage of blasting vibration to realize energy distribution and attenuation lawof single-hole blasting vibration signal. With the measured single-holeblasting vibration velocity curves, used wavelet packet analysis technologywith high-resolution character, the law of energy distribution of single-holeblasting vibration signals in different frequency bands, and the effect ofblasting source and distance from the source on single-hole blasting vibrationsignal energy distribution were analysised. The results show that the energy ofsingle-hole blasting vibration signals attenuation very quickly in thefrequency domain concentration distribution in 0~100Hz; and distance from thesource has significant influence on energy distribution in the frequencydomain; The energy is mainly distributed in the low frequency band whendistance from the source is larger, which has guiding significance inmitigation of blast-induced vibrations.

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Chen, Rongxin, Qing Han, Lianghui Zheng, Lingling Jiang, and Jianying Yan. "Establishment and assessment of a nomogram for predicting adverse outcomes of preterm preeclampsia." Journal of International Medical Research 48, no. 7 (July 2020): 030006052091182. http://dx.doi.org/10.1177/0300060520911828.

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Objective This prospective study was designed to develop and internally validate an accurate prognostic nomogram model with which to predict the adverse outcomes of preterm preeclampsia. Methods Pregnant women with preeclampsia were divided into the adverse outcome group and the no adverse outcome group. The Kaplan–Meier method, univariate Cox regression analysis, and calculation of the concordance index (C-index) were applied to predictive evaluation of the nomogram. Calibration curves were drawn to test the nomogram prediction and actual observation of the adverse outcome rate. Results After 1000 internal validations of bootstrap resampling, the C-index of the nomogram for predicting adverse outcomes within 48 hours was 0.74 and the cut-off value was 0.53, with a sensitivity of 61.57% and a specificity of 76.93%. The C-index of the nomogram for predicting adverse outcomes within 7 days was 0.76 and the cut-off value was 0.37, with a sensitivity of 58.17% and a specificity of 84.82%. The calibration curves showed good concordance of incidence of adverse outcomes between nomogram prediction and actual observation. Conclusion Cox regression has certain guiding significance in preventing and treating adverse outcomes, choosing the time of termination of pregnancy, and improving the prognosis of the mother and child.

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Wang, Yang, Ping Wang, Jun Xie, Zhaorui Yin, Xiaoyan Lin, Yuanhong Zhao, Zheng Li, et al. "Pharmacokinetic Comparisons of Different Combinations of Yigan Jiangzhi Formula in Rats: Simultaneous Determination of Fourteen Components by UPLC-MS/MS." Journal of Analytical Methods in Chemistry 2020 (March 21, 2020): 1–16. http://dx.doi.org/10.1155/2020/9353975.

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A rapid, specific, and sensitive analysis for simultaneous determination of fourteen components (daidzein, fermononetin, apigenin, luteolin, puerarin, ononin, calycosin-7-O-β-D-glucoside, tanshinol, rosmarinic acid, alkanoic acid, salvianolic acid B, berberine, jatrorrhizin, and palmatine) of Yigan Jiangzhi formula (YGJZF, a clinical experienced formula for damp-heat syndrome) in rat plasma was developed and validated using ultraperformance liquid chromatography coupled with mass spectrometry. Lower limit of quantitation ranged from 0.2–10.0 ng/mL, and the calibration curves showed good linearity over 500 times of measuring range. The validated method was successfully applied to the pharmacokinetics investigation of the fourteen compounds in rat plasma after oral administration of two different doses of YGJZF. Compared with the low-dose group of YGJZF, the high-dose group showed significant increase (P<0.01 or P<0.05) in maximum plasma concentration, maximum concentration time, and area under the plasma concentration-time curve and decrease (P<0.01 or P<0.05) in clearance of most of the fourteen analytes, which suggested that the bioavailability of these components could be enhanced by increasing dosage. The above results may provide useful information for cognizing the relationship between in vitro and in vivo data of the fourteen bioactive ingredients of YGJZF and further guiding rational clinical drug prescription.

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Korte, Sara, Veerle Boel, Wouter de Corte, and Geert de Schutter. "Vibrated Concrete vs. Self-Compacting Concrete: Comparison of Fracture Mechanics Properties." Key Engineering Materials 601 (March 2014): 199–202. http://dx.doi.org/10.4028/www.scientific.net/kem.601.199.

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This study focuses on the fracture mechanics aspect of self-compacting concrete, compared to vibrated concrete. The most commonly used experiments to investigate the toughness and cracking behaviour of concrete are the three-point bending test (3PBT) on small, notched beams, and the wedge-splitting test (WST) on cubic samples with guiding groove and starter notch. From the resulting P-CMOD curves (applied load versus crack mouth opening displacement), different fracture parameters, such as fracture energy and fracture toughness, can be extracted. Moreover, using inverse analysis, the σ-w relationship (tensile stress versus crack width) can be derived. This paper lists the results of a series of tests on samples, made of VC, SCC of equal strength, and SCC with identical w/c factor. Subsequently, a comparison of the mechanical characteristics is made, revealing important differences regarding several fracture parameters.

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Li, Wen Pu. "Experimental Study of Mechanical and Seepage Characteristics of Two Kinds of Coal Samples." Advanced Materials Research 1073-1076 (December 2014): 2098–101. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.2098.

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Mechanical and seepage characteristics of raw coal samples are the most important research contents of enhancing coal bed methane recovery, but the produce of raw coal sample is very difficult. Based on gas seepage instrument, mechanical and seepage characteristics were performed on normal briquette coal samples and coal samples containing gypsum. The results show that it can increase the cohesion and intensity level by adding gypsum in briquette coal. Porosity and permeability of coal containing gypsum is less than ordinary briquette coal sample. Permeability with axial strain curves of two kinds of coal samples can be fitted with a quadratic function well. In expansion stage, volumetric strain of ordinary coal sample is much smaller than the coal samples containing gypsum. The research has an important guiding significance on enhancing coal bed methane recovery and gateway supporting.

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Agboola, AbdulhameedKayode, and Ibrahim Yusuf. "INTERFACE OF SOCIAL MEDIA IN CONVENTIONAL MEDIA IN NIGERIA: AN OVERVIEW." International Journal of Research -GRANTHAALAYAH 3, no. 6 (June 30, 2015): 17–32. http://dx.doi.org/10.29121/granthaalayah.v3.i6.2015.2996.

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Technology will continue to develop and change how journalism is practice, it will bring with it new challenges and learning curves. What will not change is the public’s demand for news and information, the kind that helps them manage their personal lives and make decisions as educated citizens in the public realm. While much discussion focuses on how we read the news, technology is changing the way we report the news. The image of a reporter showing up to a scene with a pen and a pad is iconic but will soon lose to the vestiges of time. This paper argues that the Newspaper media will continue to satisfy this public demand using the new tools of technological innovation. They will expand their audiences and engage them in novel and exciting ways. Therefore, justice was done to the discussion by providing answers to the following guiding questions: In what form are social media projected / displayed in prints and electronic media? What use have they been put into? For what purpose are they being used for? These are the guiding questions that the study aims to answer in this study. The study concludes that the Nigeria media sector can now be said to be equally exploring new media to leverage on its activities. Finally, the paper recommends that other newspapers in Nigeria should emulate The Punch newspaper and Channel TV in capturing new media in their daily print and broadcast contents.

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Wang, Wei, Fengying Wu, and Ziyi Wang. "Revising Seismic Vulnerability of Bridges Based on Bayesian Updating Method to Evaluate Traffic Capacity of Bridges." Sustainability 12, no. 5 (March 2, 2020): 1898. http://dx.doi.org/10.3390/su12051898.

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Analyzing the seismic vulnerability of bridge structures is of great significance in assessing the sustainable capacity of bridges. However, previous seismic vulnerability analysis of bridge structures was based on theoretical simulation or experimental research, which couldn’t really reflect the actual seismic damage. Therefore, this paper used Bayesian updating method to obtain a corrected vulnerability curve of bridge structures considering the theoretical simulation and historical seismic data, which overcame the shortcomings that information couldn’t be updated. Specifically speaking, the seismic demand probability function of the bridge structure was obtained through numerical simulation, and a seismic vulnerability curve of a log-normal distribution with two parameters (median value c j and log-standard deviation ξ j ) was established, which was taken as the prior information. Then, combining the historical empirical damage data, the demand information is updated to obtain the posterior probability of the structural seismic demand. The possibility of exceeding the limit damage state of the bridge structure under different ground motion intensity can be obtained by using the corrected seismic vulnerability curve. The results show that the corrected seismic vulnerability curves are closer to theoretical simulation results, which provides a new idea for the reliability analysis of the bridge structure. Moreover, based on the corrected seismic vulnerability curve of Guxigou Middle Bridge, the post-earthquake traffic capacity of the bridge was evaluated by combining with traffic flow and traffic time. The research results show that the proposed method can quickly evaluate the sustainable traffic capacity of bridges after earthquakes, which has certain practicability and scientificity and provides the theoretical basis and practical guiding significance for the relief work after earthquakes.

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