In this paper, we first give the concept of weakly P-inversive semigroup S（P）. Then we describe the strong P-congruences on S（P） in terms of their P-kernel normal systems. It is proved that there is a bijection be...In this paper, we first give the concept of weakly P-inversive semigroup S（P）. Then we describe the strong P-congruences on S（P） in terms of their P-kernel normal systems. It is proved that there is a bijection between the strong P-congruences and the P-kernel normal systems. Finally, it is also prove that the lattice of strong P-congruences and the lattice of P-kernel normal systems on S（P） are isomorphic.展开更多
Let S（P） be a P-inversive semigroup. In this paper we describe the strong P-congruences on S（P） in terms of their P-kernel normal systems. We prove that any strong P-congruence on S（P） can present a P-kernel nor...Let S（P） be a P-inversive semigroup. In this paper we describe the strong P-congruences on S（P） in terms of their P-kernel normal systems. We prove that any strong P-congruence on S（P） can present a P-kernel normal system; conversely any P-kernel normal system of S（P） can determine a strong P-congruence.展开更多
Background:Isotonic crystalloids are recommended as the first choice for fluid therapy in acute pan-creatitis(AP),with normal saline(NS)and lactate Ringer’s(LR)used most often.Evidence based recom-mendations on the t...Background:Isotonic crystalloids are recommended as the first choice for fluid therapy in acute pan-creatitis(AP),with normal saline(NS)and lactate Ringer’s(LR)used most often.Evidence based recom-mendations on the type of fluid are conflicting and generally come from small single-center randomized controlled trials(RCTs).We therefore conducted a systematic review and meta-analysis to compare the effect of balanced solutions(BS)versus NS on patient-centered clinical outcomes in AP.Methods:From four databases searched up to October 2024,we included only RCTs of adult patients with AP that compared the use of BS(including LR,acetate Ringer’s,etc.)with NS.The primary out-come was the disease advances from AP to moderately severe and severe AP(MSAP/SAP).Trial sequential analyses(TSA)were conducted to control for type-I and type-II errors and Grading of Recommendations Assessment,Development,and Evaluation(GRADE)was used to assess the quality of evidence.Results:Six RCTs were identified and included,involving 260 patients treated with BS and 298 patients with NS.Patients who received the BS had less MSAP/SAP[odds ratio(OR)=0.50,95%confidence in-terval(CI):0.29 to 0.85,P=0.01,I^(2)=0%;5 studies,299 patients],reduced the need of ICU admission(OR=0.60,95%CI:0.39 to 0.93,P=0.02,I^(2)=0%;5 studies,507 patients)and shorter length of hospital stay[mean difference(MD)=-0.88,95%CI:-1.48 to-0.28,P=0.004,I^(2)=0%;6 studies,558 patients;confirmed by TSA with high certainty]compared with those who received NS.The evidence for most of the clinical outcomes was rated as moderate to low due to the risk of bias,imprecision and inconsistency.Conclusions:BS,compared with NS,was associated with improved clinical outcomes in patients with AP.However,given the moderate to low quality of evidence for most of the outcomes assessed,further trials are warranted.展开更多
Under the National Innovation-Driven Development Strategy,establishing a scientifically sound evaluation system for normal university students’innovation and entrepreneurship capabilities serves as a crucial foundati...Under the National Innovation-Driven Development Strategy,establishing a scientifically sound evaluation system for normal university students’innovation and entrepreneurship capabilities serves as a crucial foundation for optimizing innovation education models and enhancing teacher candidates’comprehensive competencies.Based on existing indicator frameworks,we designed a questionnaire and applied exploratory factor analysis(EFA)to screen indicators,reduce dimensionality,and analyze weighting.This process identified key metrics for evaluating pedagogical students’innovation capacities,ultimately constructing a targeted assessment system for normal university students.The study provides theoretical support for cultivating teacher trainees’innovative capabilities while contributing to the national innovation strategy implementation.展开更多
Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to th...Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions.This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load(DNL)boundary from both laboratory experiments and discrete element method(DEM)simulations.The research investigates the influence of normal dynamic load amplitude(An)and rock type on shear strength parameters,elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading,with maximum shear load decreasing by 36.81%to 46.94%as An increases from 10%to 70%when rock type varies from coal to limestone.Through analysis of strain field evolution,the critical impact of rock type on localization of shear failure surface is revealed,with systematic summarization of differentiated wear characteristics,failure modes,and key controlling factors associated with shear failure surface.Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries,clarify rock type dependent crack propagation pathways,and quantitatively assess the damage extent of shear failure surface,with the anisotropic interface damage factor increasing from 34.9%to 56.6%as An rises from 10%to 70%,and decreasing from 49.6%to 23.4%as rock type varies from coal to limestone.展开更多
Nursing education in Indonesia experienced a number of changes during the new normal.The biopsychosocial health status reveals how students can complete their studies well at nursing school in the new normal.A quantit...Nursing education in Indonesia experienced a number of changes during the new normal.The biopsychosocial health status reveals how students can complete their studies well at nursing school in the new normal.A quantitative,descriptive correlational study sampled 368 student nurses from2 universities.This study used a biopsychosocial questionnaire,which included biological,physiological,and social dimensions.In this study,there was no significant demographic student nurse relationship with the biological,psychological,and social dimensions of health,at P-value 0.05(Age P=0.70,P=0.27,P=0.93)sex(P=1,P=0.919,P=0.5),as well as grade level(P=0.9,P=0.37,P=0.64).Student nurses were dynamic,such as process input,resulting in coping adaptation and the ability to care for themselves.There was a relationship between both universities with a psychological dimension and a P-value of 0.049.In terms of Generation Z technology,both universities played a role.Lifestyle influences can lead to intense feelings of isolation and loneliness in some teens,including self-negativity,fear of missing out on information,and shame about not meeting appropriate standards for social media.The influence of an unhealthy lifestyle impacts stress and anxiety.The student nurses assigned considered themselves to be“healthy”in terms of their biopsychosocial health status.Student nurses continued to develop in their biopsychosocial health by utilizing different coping strategies to adapt and adjust to their environment in their school of nursing.展开更多
Let G be a finite group and H a subgroup of G.The normal index of H in G is defined as the order of K/H_(G),where K is a normal supplement of H in G such that|K|is minimal and H_(G)≤K■G.Let p be a prime which divide...Let G be a finite group and H a subgroup of G.The normal index of H in G is defined as the order of K/H_(G),where K is a normal supplement of H in G such that|K|is minimal and H_(G)≤K■G.Let p be a prime which divides the order of a group G.In this paper,some characterizations of G being p-solvable or p-supersolvable were obtained by analyzing the normal index of certain subgroups of G.These results can be viewed as local version of recent results in the literature.展开更多
A model for dynamic frictionless contact between a viscoelastic body and foundation is considered.The viscoelastic constitutive law is assumed to be nonlinear and the contact is modelled with the normal compliance con...A model for dynamic frictionless contact between a viscoelastic body and foundation is considered.The viscoelastic constitutive law is assumed to be nonlinear and the contact is modelled with the normal compliance condition.We obtain the well-posedness using nonlinear semigroup theory arguments.Moreover,the exponential stability result of the solution is shown by using the energy method to produce a suitable Lyapunov function.展开更多
Intermittent joints are common in rock masses and are subjected to cyclic shear loads from seismic events,environmental factors,and human activities.In this study,we conducted cyclic shear tests to investigate the eff...Intermittent joints are common in rock masses and are subjected to cyclic shear loads from seismic events,environmental factors,and human activities.In this study,we conducted cyclic shear tests to investigate the effect of joint geometry(persistence,overlap,and spacing)on the cyclic shear behavior of intermittent joints under constant normal stiffness conditions.Our results revealed step‐path failure surfaces comprising tensile and shear failure surfaces.Shear failure surface controlled the degradation of shear properties,with shear strength decreasing progressively with cycles,ranging from 74.07%to 97.94%.Intermittent joints exhibited significant compressibility,with dilation predominant in early cycles and compression in later ones.Shear strength and dilation were more sensitive to joint persistence and spacing than overlap.Friction coefficients showed nonmonotonic variations with cycle number.High persistence,moderate overlap,and small spacing were identified as the most destabilizing combination.These findings offer valuable insights for stability assessment and deformation characterization in deep rock engineering.展开更多
Liquid core reduction(LCR)technology,originally developed for continuous thin-slab casting,allows space for a submerged entry nozzle in a mold while improving production efficiency.Recent experimental attempts explore...Liquid core reduction(LCR)technology,originally developed for continuous thin-slab casting,allows space for a submerged entry nozzle in a mold while improving production efficiency.Recent experimental attempts explore the implementation of LCR in regular slab casting processes.However,regular slabs(2–3 times thicker than thin slabs)face critical challenges in terms of excessive deformation and stress concentration under external forces,which induce intermediate cracks and thus hinder successful LCR adoption in regular slab production.This study evaluates the feasibility of LCR for producing regular slabs and identifies optimal reduction parameters to prevent crack initiation.A three-dimensional thermal–mechanical coupled model is proposed using the finite element method(FEM),integrated with the equivalent replacement liquid steel(ERLS)method and the normalized Cockcroft–Latham damage model,to achieve quantitative prediction of intermediate crack risk during the LCR process.The ERLS model simulates the extrusion flow and expulsion behavior of the liquid core,and its accuracy is validated against actual production measurements.To identify the critical damage value leading to intermediate crack initiation,this study conducts a consistency analysis between high-temperature tensile tests and FEM-based simulations using damage models.Based on this value,crack prediction is performed for Q355 slabs with cross-sectional dimensions of 170 mm×1450 mm.Using the prediction results,an optimal reduction scheme is determined,wherein the second segment accounts for 50%of the total reduction,the third segment for 32.5%,and the fourth segment for 17.5%,with the theoretical value of maximum reduction being 34 mm.These results provide actionable guidelines for the potential implementation of LCR in regular slab-casting systems.展开更多
A novel approach is proposed to detect the normal vector to product surface in real time for the robotic precision drilling system in aircraft component assembly, and the auto-normalization algorithm is presented base...A novel approach is proposed to detect the normal vector to product surface in real time for the robotic precision drilling system in aircraft component assembly, and the auto-normalization algorithm is presented based on the detection system. Firstly, the deviation between the normal vector and the spindle axis is measured by the four laser displacement sensors installed at the head of the multi-function end effector. Then, the robot target attitude is inversely solved according to the auto-normalization algorithm. Finally, adjust the robot to the target attitude via pitch and yaw rotations about the tool center point and the spindle axis is corrected in line with the normal vector simultaneously. To test and verify the auto-normalization algorithm, an experimental platform is established in which the laser tracker is introduced for accurate measurement. The results show that the deviations between the corrected spindle axis and the normal vector are all reduced to less than 0.5°, with the mean value 0.32°. It is demonstrated the detection method and the autonormalization algorithm are feasible and reliable.展开更多
The electro-hydraulic servo system was studied to cancel the amplitude attenuation and phase delay of its sinusoidal response,by developing a network using normalized least-mean-square (LMS) adaptive filtering algorit...The electro-hydraulic servo system was studied to cancel the amplitude attenuation and phase delay of its sinusoidal response,by developing a network using normalized least-mean-square (LMS) adaptive filtering algorithm.The command input was corrected by weights to generate the desired input for the algorithm,and the feedback was brought into the feedback correction,whose output was the weighted feedback.The weights of the normalized LMS adaptive filtering algorithm were updated on-line according to the estimation error between the desired input and the weighted feedback.Thus,the updated weights were copied to the input correction.The estimation error was forced to zero by the normalized LMS adaptive filtering algorithm such that the weighted feedback was equal to the desired input,making the feedback track the command.The above concept was used as a basis for the development of amplitude phase control.The method has good real-time performance without estimating the system model.The simulation and experiment results show that the proposed amplitude phase control can efficiently cancel the amplitude attenuation and phase delay with high precision.展开更多
In the northwest of the Himalayan-Tibetan Orogen, the ~250 km-long Kongur Shan extensional system in the eastern Pamir was formed during the convergence between the Indian and Asian plates. Tectonic activity of the Ko...In the northwest of the Himalayan-Tibetan Orogen, the ~250 km-long Kongur Shan extensional system in the eastern Pamir was formed during the convergence between the Indian and Asian plates. Tectonic activity of the Kongur Shan normal fault and the Tashkurgan normal fault can help to reveal the origin of east-west extension along the Kongur Shan extensional system. The Kongur Shan fault has been extensively studied, while the Tashkurgan fault calls for systemic research. In this study, low-temperature thermochronology including apatite fission track analysis and apatite and zircon(U-Th)/He analyses is applied to constrain the timing of activity of the Tashkurgan fault. Results indicate that the Tashkurgan fault initiated at 10–5 Ma, and most likely at 6–5 Ma. The footwall of the Tashkurgan fault has been exhumed at an average exhumation rate of 0.6–0.9 mm/a since the initiation of the Tashkurgan fault. Combined with previous research on the Kongur Shan fault, we believe that the origin of east-west extension along the Kongur Shan extensional system was driven by gravitational collapse of over-thickened Pamir crust.展开更多
In this paper, the normal Luenberger function observer design for second-order descriptor linear systems is considered. It is shown that the main procedure of the design is to solve a so-called second-order generalize...In this paper, the normal Luenberger function observer design for second-order descriptor linear systems is considered. It is shown that the main procedure of the design is to solve a so-called second-order generalized Sylvester-observer matrix equation. Based on an explicit parametric solution to this equation, a parametric solution to the normal Luenberger function observer design problem is given. The design degrees of freedom presented by explicit parameters can be further utilized to achieve some additional design requirements.展开更多
This paper proposes a novel method to quantify the error of a nominal normalized right graph symbol （NRGS） for an errors- in-variables （EIV） system corrupted with bounded noise. Following an identification framewo...This paper proposes a novel method to quantify the error of a nominal normalized right graph symbol （NRGS） for an errors- in-variables （EIV） system corrupted with bounded noise. Following an identification framework for estimation of a perturbation model set, a worst-case v-gap error bound for the estimated nominal NRGS can be first determined from a priori and a posteriori information on the underlying EIV system. Then, an NRGS perturbation model set can be derived from a close relation between the v-gap metric of two models and H∞-norm of their NRGSs＇ difference. The obtained NRGS perturbation model set paves the way for robust controller design using an H∞ loop-shaping method because it is a standard form of the well-known NCF （normalized coprime factor） perturbation model set. Finally, a numerical simulation is used to demonstrate the effectiveness of the proposed identification method.展开更多
The simplest normal form of resonant double Hopf bifurcation was studied based on Lie operator. The coefficients of the simplest normal forms of resonant double Hopf bifurcation and the nonlinear transformations in te...The simplest normal form of resonant double Hopf bifurcation was studied based on Lie operator. The coefficients of the simplest normal forms of resonant double Hopf bifurcation and the nonlinear transformations in terms of the original system coefficients were given explicitly. The nonlinear transformations were used for reducing the lower- and higher-order normal forms, and the rank of system matrix was used to determine the coefficient of normal form which could be reduced. These make the gained normal form simpler than the traditional one. A general program was compiled with Mathematica. This program can compute the simplest normal form of resonant double Hopf bifurcation and the non-resonant form up to the 7th order.展开更多
A tube model to simulate the normal black smoker system has been built, where the Darcy flow equation, the Ergun equation and the turbulent pipe flow equation are used respectively to describe the dynamic process of d...A tube model to simulate the normal black smoker system has been built, where the Darcy flow equation, the Ergun equation and the turbulent pipe flow equation are used respectively to describe the dynamic process of different key areas in the hydrothermal circulation system. At the same time, a convection - diffuse Equation for the temperature field is used for describe the exchange of thermal energy and the law of temperature variation. Combining the above facts and using efficient mathematical algorithms and programming with the MatLab programming language, the variation curves of temperature, pressure and mass flow rate are determined, while also the dynamic heat equilibrium and pressure equilibrium within the black smoker system are analyzed. On the basis of the model of the normal black smoker system, a megaplume formation model is further built. For instance, the hydrothermal venting plume on the Juan de Fuca Ridge has been simulated and the simulation results are fairly consistent with Baker＇ s imputed data in 1986. On the basis of the above productive simulation, a series of factors for megaplume formation and the effectiveness of the main parameters of the periodicity of the megaplume formation, temperature and the maximum mass flow rate are systematically discussed. Main conclusions are as follows： The normal black smoker system can evolve into a megaplum eruption. In fact, the passageway of the hydrothermal discharge is blocked by the hydrothermal sediments during the black smoker period, which leads to a hydrothermal fluid accumulation, rise of temperature and increase of buoyancy pressure under the seabed. After a period of 2 - 3 a, the megaplume hydrothermal eruption will occur when the increasing buoyancy pressure is high enough to crack the blockage （cap）. Meanwhile, the temperature of the heat source must exceed 500 ℃, while the highest temperature of the eruption fluid may be high up to 413 ℃, which is fairly consistent with the surveying data. If the temperature of the heat source were to be higher than 500 ℃, then the critical period for the megaplume formation could be obviously curtailed to be less than 1 a, while the critical temperature and the maximum mass flow rate are nearly invariable. As the permeability increases, the maximum mass flow rate increases gradually close to a steady value.展开更多
The nonlinear normal modes (NNMs) associated with integrnal resonance can be classified into two kinds: uncoupled and coupled. The bifurcation problem of the coupled NNM of system with 1 : 2 : 5 dual internal resonanc...The nonlinear normal modes (NNMs) associated with integrnal resonance can be classified into two kinds: uncoupled and coupled. The bifurcation problem of the coupled NNM of system with 1 : 2 : 5 dual internal resonance is in two variables. The singular analysis of it is presented after separating the two variables by taking advantage of Maple algebra, and some new bifurcation patterns are found. Different from the NNMs of systems with single internal resonance, the number of the NNMs of systems with dual internal resonance may be more or less than the number of the degrees of freedom. At last, it is pointed out that bifurcation problems in two variables can be conveniently solved by separating variables as well as using coupling equations.展开更多
English practice teaching has outstanding superiority over the extension and supplementation of English classroom teaching, and practice teaching is an indispensably important part of college English teaching. To stud...English practice teaching has outstanding superiority over the extension and supplementation of English classroom teaching, and practice teaching is an indispensably important part of college English teaching. To students, cultivation of the ability of practice is vital, affecting students＇ employment and future. To universities, teaching quality has a direct impact on the development prospect of schools and decides the future of schools. Moreover, local normal universities also undertake a more important task to cultivate local high-quality talents teaching primary and junior high schools. These teaching talents undertake the great task of English teaching over primary and junior high school students, and thus the construction and implementation of practice teaching system of English major in normal universities are urgent.展开更多
1 INTRODUCTIONAfter Prausnitz et al.published the perturbed hard-sphere chain theory(PHCT),manymodified theories have been put forward,such as the perturbed soft-sphere chain theory(PSCT),the perturbed anisotropic cha...1 INTRODUCTIONAfter Prausnitz et al.published the perturbed hard-sphere chain theory(PHCT),manymodified theories have been put forward,such as the perturbed soft-sphere chain theory(PSCT),the perturbed anisotropic chain theory(PACT)and the associated perturbedanisotropic chain theory(APACT).These theories are all concerned with the parameter3c.But,Wertheim in his work proved that the free energy of hard-sphere chain couldbe calculated without 3c.Induced by the work done by Wertheim,Chapman展开更多
基金the Science Research Foundation of Qingdao Technological University(C2002-214)
文摘In this paper, we first give the concept of weakly P-inversive semigroup S（P）. Then we describe the strong P-congruences on S（P） in terms of their P-kernel normal systems. It is proved that there is a bijection between the strong P-congruences and the P-kernel normal systems. Finally, it is also prove that the lattice of strong P-congruences and the lattice of P-kernel normal systems on S（P） are isomorphic.
文摘Let S（P） be a P-inversive semigroup. In this paper we describe the strong P-congruences on S（P） in terms of their P-kernel normal systems. We prove that any strong P-congruence on S（P） can present a P-kernel normal system; conversely any P-kernel normal system of S（P） can determine a strong P-congruence.
文摘Background:Isotonic crystalloids are recommended as the first choice for fluid therapy in acute pan-creatitis(AP),with normal saline(NS)and lactate Ringer’s(LR)used most often.Evidence based recom-mendations on the type of fluid are conflicting and generally come from small single-center randomized controlled trials(RCTs).We therefore conducted a systematic review and meta-analysis to compare the effect of balanced solutions(BS)versus NS on patient-centered clinical outcomes in AP.Methods:From four databases searched up to October 2024,we included only RCTs of adult patients with AP that compared the use of BS(including LR,acetate Ringer’s,etc.)with NS.The primary out-come was the disease advances from AP to moderately severe and severe AP(MSAP/SAP).Trial sequential analyses(TSA)were conducted to control for type-I and type-II errors and Grading of Recommendations Assessment,Development,and Evaluation(GRADE)was used to assess the quality of evidence.Results:Six RCTs were identified and included,involving 260 patients treated with BS and 298 patients with NS.Patients who received the BS had less MSAP/SAP[odds ratio(OR)=0.50,95%confidence in-terval(CI):0.29 to 0.85,P=0.01,I^(2)=0%;5 studies,299 patients],reduced the need of ICU admission(OR=0.60,95%CI:0.39 to 0.93,P=0.02,I^(2)=0%;5 studies,507 patients)and shorter length of hospital stay[mean difference(MD)=-0.88,95%CI:-1.48 to-0.28,P=0.004,I^(2)=0%;6 studies,558 patients;confirmed by TSA with high certainty]compared with those who received NS.The evidence for most of the clinical outcomes was rated as moderate to low due to the risk of bias,imprecision and inconsistency.Conclusions:BS,compared with NS,was associated with improved clinical outcomes in patients with AP.However,given the moderate to low quality of evidence for most of the outcomes assessed,further trials are warranted.
基金Mid-term Results of the 2024 Langfang Normal University Special Teaching Reform Project on Innovation and Entrepreneurship Education Reform,“Research on the Evaluation System of Innovation and Entrepreneurship Ability for Normal University Students Based on Big Data Application-A Case Study of Langfang Normal University”(Project No.:CXJG2024-06)。
文摘Under the National Innovation-Driven Development Strategy,establishing a scientifically sound evaluation system for normal university students’innovation and entrepreneurship capabilities serves as a crucial foundation for optimizing innovation education models and enhancing teacher candidates’comprehensive competencies.Based on existing indicator frameworks,we designed a questionnaire and applied exploratory factor analysis(EFA)to screen indicators,reduce dimensionality,and analyze weighting.This process identified key metrics for evaluating pedagogical students’innovation capacities,ultimately constructing a targeted assessment system for normal university students.The study provides theoretical support for cultivating teacher trainees’innovative capabilities while contributing to the national innovation strategy implementation.
基金support from the National Natural Science Foundation of China(Nos.51504247,52174092,51904290,and 52074259)the Natural Science Foundation of Jiangsu Province,China(No.BK20220157)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)the China University of Mining and Technology(CUMT)Open Sharing Fund for Large-scale Instruments and Equipment(No.DYGX-2025-47)is gratefully acknowledged.
文摘Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions.This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load(DNL)boundary from both laboratory experiments and discrete element method(DEM)simulations.The research investigates the influence of normal dynamic load amplitude(An)and rock type on shear strength parameters,elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading,with maximum shear load decreasing by 36.81%to 46.94%as An increases from 10%to 70%when rock type varies from coal to limestone.Through analysis of strain field evolution,the critical impact of rock type on localization of shear failure surface is revealed,with systematic summarization of differentiated wear characteristics,failure modes,and key controlling factors associated with shear failure surface.Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries,clarify rock type dependent crack propagation pathways,and quantitatively assess the damage extent of shear failure surface,with the anisotropic interface damage factor increasing from 34.9%to 56.6%as An rises from 10%to 70%,and decreasing from 49.6%to 23.4%as rock type varies from coal to limestone.
文摘Nursing education in Indonesia experienced a number of changes during the new normal.The biopsychosocial health status reveals how students can complete their studies well at nursing school in the new normal.A quantitative,descriptive correlational study sampled 368 student nurses from2 universities.This study used a biopsychosocial questionnaire,which included biological,physiological,and social dimensions.In this study,there was no significant demographic student nurse relationship with the biological,psychological,and social dimensions of health,at P-value 0.05(Age P=0.70,P=0.27,P=0.93)sex(P=1,P=0.919,P=0.5),as well as grade level(P=0.9,P=0.37,P=0.64).Student nurses were dynamic,such as process input,resulting in coping adaptation and the ability to care for themselves.There was a relationship between both universities with a psychological dimension and a P-value of 0.049.In terms of Generation Z technology,both universities played a role.Lifestyle influences can lead to intense feelings of isolation and loneliness in some teens,including self-negativity,fear of missing out on information,and shame about not meeting appropriate standards for social media.The influence of an unhealthy lifestyle impacts stress and anxiety.The student nurses assigned considered themselves to be“healthy”in terms of their biopsychosocial health status.Student nurses continued to develop in their biopsychosocial health by utilizing different coping strategies to adapt and adjust to their environment in their school of nursing.
基金Supported by the National Natural Science Foundation of China(Grant No.12071092)Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515012072)+1 种基金the Natural Science Research Project of Anhui Educational Committee(Grant No.2024AH051298)the Scientific Research Foundation of Bozhou University(Grant No.BYKQ202419).
文摘Let G be a finite group and H a subgroup of G.The normal index of H in G is defined as the order of K/H_(G),where K is a normal supplement of H in G such that|K|is minimal and H_(G)≤K■G.Let p be a prime which divides the order of a group G.In this paper,some characterizations of G being p-solvable or p-supersolvable were obtained by analyzing the normal index of certain subgroups of G.These results can be viewed as local version of recent results in the literature.
文摘A model for dynamic frictionless contact between a viscoelastic body and foundation is considered.The viscoelastic constitutive law is assumed to be nonlinear and the contact is modelled with the normal compliance condition.We obtain the well-posedness using nonlinear semigroup theory arguments.Moreover,the exponential stability result of the solution is shown by using the energy method to produce a suitable Lyapunov function.
基金National Natural Science Foundation of China,Grant/Award Number:42172292Shandong Energy Group,Grant/Award Number:SNKJ2022A01-R26Taishan Scholars Project Special Funding。
文摘Intermittent joints are common in rock masses and are subjected to cyclic shear loads from seismic events,environmental factors,and human activities.In this study,we conducted cyclic shear tests to investigate the effect of joint geometry(persistence,overlap,and spacing)on the cyclic shear behavior of intermittent joints under constant normal stiffness conditions.Our results revealed step‐path failure surfaces comprising tensile and shear failure surfaces.Shear failure surface controlled the degradation of shear properties,with shear strength decreasing progressively with cycles,ranging from 74.07%to 97.94%.Intermittent joints exhibited significant compressibility,with dilation predominant in early cycles and compression in later ones.Shear strength and dilation were more sensitive to joint persistence and spacing than overlap.Friction coefficients showed nonmonotonic variations with cycle number.High persistence,moderate overlap,and small spacing were identified as the most destabilizing combination.These findings offer valuable insights for stability assessment and deformation characterization in deep rock engineering.
基金financially supported by the Na-tional Natural Science Foundation of China (No.52474355)the Fundamental Research Funds for the Central Uni-versities,China (No.N25DCG006).
文摘Liquid core reduction(LCR)technology,originally developed for continuous thin-slab casting,allows space for a submerged entry nozzle in a mold while improving production efficiency.Recent experimental attempts explore the implementation of LCR in regular slab casting processes.However,regular slabs(2–3 times thicker than thin slabs)face critical challenges in terms of excessive deformation and stress concentration under external forces,which induce intermediate cracks and thus hinder successful LCR adoption in regular slab production.This study evaluates the feasibility of LCR for producing regular slabs and identifies optimal reduction parameters to prevent crack initiation.A three-dimensional thermal–mechanical coupled model is proposed using the finite element method(FEM),integrated with the equivalent replacement liquid steel(ERLS)method and the normalized Cockcroft–Latham damage model,to achieve quantitative prediction of intermediate crack risk during the LCR process.The ERLS model simulates the extrusion flow and expulsion behavior of the liquid core,and its accuracy is validated against actual production measurements.To identify the critical damage value leading to intermediate crack initiation,this study conducts a consistency analysis between high-temperature tensile tests and FEM-based simulations using damage models.Based on this value,crack prediction is performed for Q355 slabs with cross-sectional dimensions of 170 mm×1450 mm.Using the prediction results,an optimal reduction scheme is determined,wherein the second segment accounts for 50%of the total reduction,the third segment for 32.5%,and the fourth segment for 17.5%,with the theoretical value of maximum reduction being 34 mm.These results provide actionable guidelines for the potential implementation of LCR in regular slab-casting systems.
基金co-supported by Key Technology Research and Development Program of Jiangsu Province, China (No. BE2011178)the Aviation Industry Innovation Fund (No. AC2011214)
文摘A novel approach is proposed to detect the normal vector to product surface in real time for the robotic precision drilling system in aircraft component assembly, and the auto-normalization algorithm is presented based on the detection system. Firstly, the deviation between the normal vector and the spindle axis is measured by the four laser displacement sensors installed at the head of the multi-function end effector. Then, the robot target attitude is inversely solved according to the auto-normalization algorithm. Finally, adjust the robot to the target attitude via pitch and yaw rotations about the tool center point and the spindle axis is corrected in line with the normal vector simultaneously. To test and verify the auto-normalization algorithm, an experimental platform is established in which the laser tracker is introduced for accurate measurement. The results show that the deviations between the corrected spindle axis and the normal vector are all reduced to less than 0.5°, with the mean value 0.32°. It is demonstrated the detection method and the autonormalization algorithm are feasible and reliable.
基金Project(50905037) supported by the National Natural Science Foundation of ChinaProject(20092304120014) supported by Specialized Research Fund for the Doctoral Program of Higher Education of China+2 种基金 Project(20100471021) supported by the China Postdoctoral Science Foundation Project(LBH-Q09134) supported by Heilongjiang Postdoctoral Science-Research Foundation,China Project (HEUFT09013) supported by the Foundation of Harbin Engineering University,China
文摘The electro-hydraulic servo system was studied to cancel the amplitude attenuation and phase delay of its sinusoidal response,by developing a network using normalized least-mean-square (LMS) adaptive filtering algorithm.The command input was corrected by weights to generate the desired input for the algorithm,and the feedback was brought into the feedback correction,whose output was the weighted feedback.The weights of the normalized LMS adaptive filtering algorithm were updated on-line according to the estimation error between the desired input and the weighted feedback.Thus,the updated weights were copied to the input correction.The estimation error was forced to zero by the normalized LMS adaptive filtering algorithm such that the weighted feedback was equal to the desired input,making the feedback track the command.The above concept was used as a basis for the development of amplitude phase control.The method has good real-time performance without estimating the system model.The simulation and experiment results show that the proposed amplitude phase control can efficiently cancel the amplitude attenuation and phase delay with high precision.
基金funded by the National Natural Science Foundation of China (Nos. 41720104003 and 41330207)the National Science and Technology Major Project of China (Nos. 2017ZX05008-001 and 2016ZX05003-001)Chen S Q receives a PhD grant (No. 201706320352) from the China Scholarship Council。
文摘In the northwest of the Himalayan-Tibetan Orogen, the ~250 km-long Kongur Shan extensional system in the eastern Pamir was formed during the convergence between the Indian and Asian plates. Tectonic activity of the Kongur Shan normal fault and the Tashkurgan normal fault can help to reveal the origin of east-west extension along the Kongur Shan extensional system. The Kongur Shan fault has been extensively studied, while the Tashkurgan fault calls for systemic research. In this study, low-temperature thermochronology including apatite fission track analysis and apatite and zircon(U-Th)/He analyses is applied to constrain the timing of activity of the Tashkurgan fault. Results indicate that the Tashkurgan fault initiated at 10–5 Ma, and most likely at 6–5 Ma. The footwall of the Tashkurgan fault has been exhumed at an average exhumation rate of 0.6–0.9 mm/a since the initiation of the Tashkurgan fault. Combined with previous research on the Kongur Shan fault, we believe that the origin of east-west extension along the Kongur Shan extensional system was driven by gravitational collapse of over-thickened Pamir crust.
基金This work was supported by National Natural Science Foundation of China(No.60710002)Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT).
文摘In this paper, the normal Luenberger function observer design for second-order descriptor linear systems is considered. It is shown that the main procedure of the design is to solve a so-called second-order generalized Sylvester-observer matrix equation. Based on an explicit parametric solution to this equation, a parametric solution to the normal Luenberger function observer design problem is given. The design degrees of freedom presented by explicit parameters can be further utilized to achieve some additional design requirements.
基金supported in part by the National Natural Science Foundation of China(Nos.61203119,61304153)the Key Program of Tianjin Natural Science Foundation,China(No.14JCZDJC36300)the Tianjin University of Technology and Education funded project(No.RC14-48)
文摘This paper proposes a novel method to quantify the error of a nominal normalized right graph symbol （NRGS） for an errors- in-variables （EIV） system corrupted with bounded noise. Following an identification framework for estimation of a perturbation model set, a worst-case v-gap error bound for the estimated nominal NRGS can be first determined from a priori and a posteriori information on the underlying EIV system. Then, an NRGS perturbation model set can be derived from a close relation between the v-gap metric of two models and H∞-norm of their NRGSs＇ difference. The obtained NRGS perturbation model set paves the way for robust controller design using an H∞ loop-shaping method because it is a standard form of the well-known NCF （normalized coprime factor） perturbation model set. Finally, a numerical simulation is used to demonstrate the effectiveness of the proposed identification method.
基金Supported by National Natural Science Foundation of China(No. 10372068).
文摘The simplest normal form of resonant double Hopf bifurcation was studied based on Lie operator. The coefficients of the simplest normal forms of resonant double Hopf bifurcation and the nonlinear transformations in terms of the original system coefficients were given explicitly. The nonlinear transformations were used for reducing the lower- and higher-order normal forms, and the rank of system matrix was used to determine the coefficient of normal form which could be reduced. These make the gained normal form simpler than the traditional one. A general program was compiled with Mathematica. This program can compute the simplest normal form of resonant double Hopf bifurcation and the non-resonant form up to the 7th order.
文摘A tube model to simulate the normal black smoker system has been built, where the Darcy flow equation, the Ergun equation and the turbulent pipe flow equation are used respectively to describe the dynamic process of different key areas in the hydrothermal circulation system. At the same time, a convection - diffuse Equation for the temperature field is used for describe the exchange of thermal energy and the law of temperature variation. Combining the above facts and using efficient mathematical algorithms and programming with the MatLab programming language, the variation curves of temperature, pressure and mass flow rate are determined, while also the dynamic heat equilibrium and pressure equilibrium within the black smoker system are analyzed. On the basis of the model of the normal black smoker system, a megaplume formation model is further built. For instance, the hydrothermal venting plume on the Juan de Fuca Ridge has been simulated and the simulation results are fairly consistent with Baker＇ s imputed data in 1986. On the basis of the above productive simulation, a series of factors for megaplume formation and the effectiveness of the main parameters of the periodicity of the megaplume formation, temperature and the maximum mass flow rate are systematically discussed. Main conclusions are as follows： The normal black smoker system can evolve into a megaplum eruption. In fact, the passageway of the hydrothermal discharge is blocked by the hydrothermal sediments during the black smoker period, which leads to a hydrothermal fluid accumulation, rise of temperature and increase of buoyancy pressure under the seabed. After a period of 2 - 3 a, the megaplume hydrothermal eruption will occur when the increasing buoyancy pressure is high enough to crack the blockage （cap）. Meanwhile, the temperature of the heat source must exceed 500 ℃, while the highest temperature of the eruption fluid may be high up to 413 ℃, which is fairly consistent with the surveying data. If the temperature of the heat source were to be higher than 500 ℃, then the critical period for the megaplume formation could be obviously curtailed to be less than 1 a, while the critical temperature and the maximum mass flow rate are nearly invariable. As the permeability increases, the maximum mass flow rate increases gradually close to a steady value.
文摘The nonlinear normal modes (NNMs) associated with integrnal resonance can be classified into two kinds: uncoupled and coupled. The bifurcation problem of the coupled NNM of system with 1 : 2 : 5 dual internal resonance is in two variables. The singular analysis of it is presented after separating the two variables by taking advantage of Maple algebra, and some new bifurcation patterns are found. Different from the NNMs of systems with single internal resonance, the number of the NNMs of systems with dual internal resonance may be more or less than the number of the degrees of freedom. At last, it is pointed out that bifurcation problems in two variables can be conveniently solved by separating variables as well as using coupling equations.
文摘English practice teaching has outstanding superiority over the extension and supplementation of English classroom teaching, and practice teaching is an indispensably important part of college English teaching. To students, cultivation of the ability of practice is vital, affecting students＇ employment and future. To universities, teaching quality has a direct impact on the development prospect of schools and decides the future of schools. Moreover, local normal universities also undertake a more important task to cultivate local high-quality talents teaching primary and junior high schools. These teaching talents undertake the great task of English teaching over primary and junior high school students, and thus the construction and implementation of practice teaching system of English major in normal universities are urgent.
基金Supported by the National Nature Science Foundation of China.
文摘1 INTRODUCTIONAfter Prausnitz et al.published the perturbed hard-sphere chain theory(PHCT),manymodified theories have been put forward,such as the perturbed soft-sphere chain theory(PSCT),the perturbed anisotropic chain theory(PACT)and the associated perturbedanisotropic chain theory(APACT).These theories are all concerned with the parameter3c.But,Wertheim in his work proved that the free energy of hard-sphere chain couldbe calculated without 3c.Induced by the work done by Wertheim,Chapman
