目的探讨限制平均生存时间(restricted mean survival time,RMST)的原理及其在脑血管病研究中的应用。方法RMST是一种稳健的生存分析方法,在满足比例风险(proportional hazards,PH)假设时可作为Cox比例风险模型的有益补充,在不满足PH假...目的探讨限制平均生存时间(restricted mean survival time,RMST)的原理及其在脑血管病研究中的应用。方法RMST是一种稳健的生存分析方法,在满足比例风险(proportional hazards,PH)假设时可作为Cox比例风险模型的有益补充,在不满足PH假设时可作为替代方法。根据PH假设检验结果,本研究对主要结局分别采用Cox比例风险模型和RMST方法进行分析。以氯吡格雷用于急性非致残性脑血管事件高危人群的疗效研究-Ⅱ(Clopidogrel with Aspirin in High-Risk Patients with Acute Nondisabling Cerebrovascular EventsⅡ,CHANCE-2)为例,计算替格瑞洛-阿司匹林组相比于氯吡格雷-阿司匹林组1年卒中复发的RMST差值;同时在中国国家卒中登记研究-Ⅲ(China National Stroke Registry-Ⅲ,CNSR-Ⅲ)中,探讨降压治疗对脑血管病合并高血压患者5年生存时间的影响。结果在CHANCE-2研究中,PH假设成立,相比于氯吡格雷-阿司匹林组,Cox回归提示替格瑞洛-阿司匹林组1年卒中复发风险下降约20%(HR=0.805,95%CI:0.682~0.949),RMST分析进一步显示,替格瑞洛-阿司匹林组在1年随访期内平均无卒中复发时间可延长约6.646 d(341.316 d vs 334.755 d,P<0.05)。在CNSR-Ⅲ研究中,PH假设不成立,多变量调整的RMST分析表明降压治疗可在5年随访期内为脑血管病合并高血压患者平均延长17.455 d生存时间,倾向性评分匹配后观察到类似结果(ΔRMST=22.883 d,P=0.011)。结论RMST不仅能在比例风险假设不满足时提供稳健的效应估计,还能以直观的时间尺度呈现临床获益,在脑血管病临床研究中具有重要的应用价值。展开更多
Electrochemical models,characterized by high fidelity and physical interpretability,have been applied in var-ious fields such as fast charging,battery state estimation,and battery material design.Currently,widely util...Electrochemical models,characterized by high fidelity and physical interpretability,have been applied in var-ious fields such as fast charging,battery state estimation,and battery material design.Currently,widely utilized single particle-based model exhibits high computational efficiency but suffers from low simulation accuracy under high-rate charge/discharge conditions.In this work,an electrochemical model for lithium-ion batteries based on multi-particle hypothesis is developed.Two particles are employed to represent the electrode char-acteristics of the positive and negative electrodes,respectively.Through theoretical derivation,mathematical equations are established to describe various processes within the battery,including solid-phase diffusion,li-quidphase diffusion,reaction polarization,and ohmic polarization.In addition,a method for obtaining model parameters is proposed.Finally,the model is experimentally validated by using lithium iron phosphate and nickel-cobalt-manganese lithium-ion batteries under constant current conditions.The identified battery elec-trochemical model parameters are within reasonable accuracy as evidenced by the experimental validation results.展开更多
Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the compu...Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.展开更多
Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain...Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results.展开更多
Background:Familiarity with a simulation platform can seduce modellers into accepting untested assumptions for convenience of implementation.These assumptions may have consequences greater than commonly suspected,and ...Background:Familiarity with a simulation platform can seduce modellers into accepting untested assumptions for convenience of implementation.These assumptions may have consequences greater than commonly suspected,and it is important that modellers remain mindful of assumptions and remain diligent with sensitivity testing.Methods:Familiarity with a technique can lead to complacency,and alternative approaches and software can reveal untested assumptions.Visual modelling environments based on system dynamics may help to make critical assumptions more evident by offering an accessible visual overview and empowering a focus on representational rather than computational efficiency.This capacity is illustrated using a cohort-based forest growth model developed for mixed species forest.Results:The alternative model implementation revealed that untested assumptions in the original model could have substantial influence on simulated outcomes.Conclusions:An important implication is that modellers should remain conscious of all assumptions,consider alternative implementations that reveal assumptions more clearly,and conduct sensitivity tests to inform decisions.展开更多
Inspired by the framework of Boyen, in this paper, an attribute-based signature（ABS） scheme from lattice assumption is proposed. In this attribute-based signature scheme, an entity＇s attributes set corresponds to t...Inspired by the framework of Boyen, in this paper, an attribute-based signature（ABS） scheme from lattice assumption is proposed. In this attribute-based signature scheme, an entity＇s attributes set corresponds to the concatenation of a lattice matrix with the sum of some random matrices, and the signature vector is generated by using the Preimage Sampling algorithm. Compared with current attribute-based signature schemes, this scheme can resist quantum attacks and enjoy shorter public-key, smaller signature size and higher efficiency.展开更多
Mechanisms of animal learning and memory were traditionally studied without reference to niche-specific functional considerations. More recently, ecological demands have informed such investigations, most notably with...Mechanisms of animal learning and memory were traditionally studied without reference to niche-specific functional considerations. More recently, ecological demands have informed such investigations, most notably with respect to foraging in birds. In parallel, behavioural ecologists, primarily concerned with functional optimization, have begun to consider the role of mechanistic factors, including cognition, to explain apparent deviations from optimal predictions. In the present paper we discuss the application of laboratory-based constructs and paradigms of cognition to the real-world challenges faced by avian foragers. We argue that such applications have been handicapped by what we term the ＇paradigmatic assumption＇ - the assumption that a given laboratory paradigm maps well enough onto a congruent cognitive mechanism （or cognitive ability） to justify confiation of the two. We present evidence against the paradigmatic assumption and suggest that to achieve a profitable integration between function and mechanism, with respect to animal cognition, a new conceptualization of cognitive mechanisms - functional cogni- tion - is required. This new conceptualization should define cognitive mechanisms based on the informational properties of the animal＇s environment and the adaptive challenges faced. Cognitive mechanisms must be examined in settings that mimic the im- portant aspects of the natural environment, using customized tasks designed to probe defined aspects of the mechanisms＇ opera- tion. We suggest that this approach will facilitate investigations of the functional and evolutionary relevance of cognitive mecha- nisms, as well as the patterns of divergence, convergence and specialization of cognitive mechanisms within and between species .展开更多
The distribution of shear stress on the cross-section of plastic metal solid circular shaft under pure torsion yielding, the applicability of complete plastic model assumption and the shear stress formula were researc...The distribution of shear stress on the cross-section of plastic metal solid circular shaft under pure torsion yielding, the applicability of complete plastic model assumption and the shear stress formula were researched. Based on the shear stress formula of circular shaft under pure torsion in elastic stage, the formula of torque in elastic stage and the definition of yield, it is obtained that the yielding stage of plastic metal shaft under pure torsion is only a surface phenomenon of torque-torsion angle relationship, and the distribution of shear stress is essentially different from that of tensile stress when yielding under uniaxial tension. The pure torsion platform-torsion angle and the shape of torque-torsion angle curve cannot change the distribution of shear stress on the shaft cross-section. The distribution of shear stress is still linear with the maximum shear stress ts. The complete plasticity model assumption is not in accordance with the actual situation of shaft under torsion. The experimental strength data of nine plastic metals are consistent with the calculated results of the new limiting strain energy strength theory （LSEST）. The traditional yield stress formula for plastic shaft under torsion is reasonable. The shear stress formula based on the plane assumption in material mechanics is applicable for all loaded stages of torsion shaft.展开更多
The article is devoted to hitherto never undertaken applying an almost unknown logically formalized axiomatic epistemology-and-axiology system called “Sigma-V” to the Third Newton’s Law of mechanics. The author has...The article is devoted to hitherto never undertaken applying an almost unknown logically formalized axiomatic epistemology-and-axiology system called “Sigma-V” to the Third Newton’s Law of mechanics. The author has continued investigating the extraordinary (paradigm-breaking) hypothesis of formal-axiological interpreting Newton’s mathematical principles of natural philosophy and, thus, has arrived to discrete mathematical modeling a system of formal axiology of nature by extracting and systematical studying its proper algebraic aspect. Along with the proper algebraic machinery, the axiomatic (hypothetic-deductive) method is exploited in this investigation systematically. The research results are the followings. 1) The Third Newton’s Law of mechanics has been modeled by a formal-axiological equation of two-valued algebraic system of metaphysics as formal axiology. (Precise defining the algebraic system is provided.) The formal-axiological equation has been established (and examined) in this algebraic system by accurate computing compositions of relevant evaluation-functions. Precise tabular definitions of the evaluation-functions are given. 2) The wonderful formula representing the Third Newton’s Law (in the relevant physical interpretation of the formal theory Sigma-V) has been derived logically in Sigma-V from the presumption of a-priori-ness of knowledge. A precise axiomatic definition of the nontrivial notion “a-priori-ness of knowledge” is given. The formal derivation is implemented in strict accordance with the rigor standard of D. Hilbert’s formalism;hence, checking the formal derivation submitted in this article is not a difficult task. With respect to proper theoretical physics, the formal inference is a nontrivial scientific novelty which has not been discussed and published elsewhere yet.展开更多
This paper presents a thorough study of the effect of the Constant Eddy Viscosity(CEV)assumption on the optimization of a discrete adjoint-based design optimization system.First,the algorithms of the adjoint methods w...This paper presents a thorough study of the effect of the Constant Eddy Viscosity(CEV)assumption on the optimization of a discrete adjoint-based design optimization system.First,the algorithms of the adjoint methods with and without the CEV assumption are presented,followed by a discussion of the two methods’solution stability.Second,the sensitivity accuracy,adjoint solution stability,and Root Mean Square(RMS)residual convergence rates at both design and offdesign operating points are compared between the CEV and full viscosity adjoint methods in detail.Finally,a multi-point steady aerodynamic and a multi-objective unsteady aerodynamic and aeroelastic coupled design optimizations are performed to study the impact of the CEV assumption on optimization.Two gradient-based optimizers,the Sequential Least-Square Quadratic Programming(SLSQP)method and Steepest Descent Method(SDM)are respectively used to draw a firm conclusion.The results from the transonic NASA Rotor 67 show that the CEV assumption can deteriorate RMS residual convergence rates and even lead to solution instability,especially at a near stall point.Compared with the steady cases,the effect of the CEV assumption on unsteady sensitivity accuracy is much stronger.Nevertheless,the CEV adjoint solver is still capable of achieving optimization goals to some extent,particularly if the flow under consideration is benign.展开更多
This study is focused on the mineralogical and chemical compositions,deposition environment and mechanism of formation of sediments of Kyzyltokoy basin.By an interpretation of formation,an environment of sedimentation...This study is focused on the mineralogical and chemical compositions,deposition environment and mechanism of formation of sediments of Kyzyltokoy basin.By an interpretation of formation,an environment of sedimentation of a basin was separated into three general conditions:a condition where glauconitization process interrupted,where process reached a completion and where occurred decay of glauconites,i.e.,the beginning and interruption in the middle of glauconitization,completion of the展开更多
Recently, many bit commitment schemes have been presented. This paper presents a new practical bit commitment scheme based on Schnorr's one-time knowledge proof scheme,where the use of cut-and-choose method and ma...Recently, many bit commitment schemes have been presented. This paper presents a new practical bit commitment scheme based on Schnorr's one-time knowledge proof scheme,where the use of cut-and-choose method and many random exam candidates in the protocols are replaced by a single challenge number. Therefore the proposed bit commitment scheme is more efficient and practical than the previous schemes In addition, the security of the proposed scheme under factoring assumption is proved, thus the cryptographic basis of the proposed scheme is clarified.展开更多
文摘目的探讨限制平均生存时间(restricted mean survival time,RMST)的原理及其在脑血管病研究中的应用。方法RMST是一种稳健的生存分析方法,在满足比例风险(proportional hazards,PH)假设时可作为Cox比例风险模型的有益补充,在不满足PH假设时可作为替代方法。根据PH假设检验结果,本研究对主要结局分别采用Cox比例风险模型和RMST方法进行分析。以氯吡格雷用于急性非致残性脑血管事件高危人群的疗效研究-Ⅱ(Clopidogrel with Aspirin in High-Risk Patients with Acute Nondisabling Cerebrovascular EventsⅡ,CHANCE-2)为例,计算替格瑞洛-阿司匹林组相比于氯吡格雷-阿司匹林组1年卒中复发的RMST差值;同时在中国国家卒中登记研究-Ⅲ(China National Stroke Registry-Ⅲ,CNSR-Ⅲ)中,探讨降压治疗对脑血管病合并高血压患者5年生存时间的影响。结果在CHANCE-2研究中,PH假设成立,相比于氯吡格雷-阿司匹林组,Cox回归提示替格瑞洛-阿司匹林组1年卒中复发风险下降约20%(HR=0.805,95%CI:0.682~0.949),RMST分析进一步显示,替格瑞洛-阿司匹林组在1年随访期内平均无卒中复发时间可延长约6.646 d(341.316 d vs 334.755 d,P<0.05)。在CNSR-Ⅲ研究中,PH假设不成立,多变量调整的RMST分析表明降压治疗可在5年随访期内为脑血管病合并高血压患者平均延长17.455 d生存时间,倾向性评分匹配后观察到类似结果(ΔRMST=22.883 d,P=0.011)。结论RMST不仅能在比例风险假设不满足时提供稳健的效应估计,还能以直观的时间尺度呈现临床获益,在脑血管病临床研究中具有重要的应用价值。
基金Supported by the National Natural Science Foundation of China(Grant Nos.52407238,52177210)the Youth Foundation of Shandong Provincial Natural Science Foundation(Grant No.ZR2023QE036).
文摘Electrochemical models,characterized by high fidelity and physical interpretability,have been applied in var-ious fields such as fast charging,battery state estimation,and battery material design.Currently,widely utilized single particle-based model exhibits high computational efficiency but suffers from low simulation accuracy under high-rate charge/discharge conditions.In this work,an electrochemical model for lithium-ion batteries based on multi-particle hypothesis is developed.Two particles are employed to represent the electrode char-acteristics of the positive and negative electrodes,respectively.Through theoretical derivation,mathematical equations are established to describe various processes within the battery,including solid-phase diffusion,li-quidphase diffusion,reaction polarization,and ohmic polarization.In addition,a method for obtaining model parameters is proposed.Finally,the model is experimentally validated by using lithium iron phosphate and nickel-cobalt-manganese lithium-ion batteries under constant current conditions.The identified battery elec-trochemical model parameters are within reasonable accuracy as evidenced by the experimental validation results.
基金Scientific Research Deanship,Taibah University Grant No.6363/436
文摘Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.
基金Project(11B033)supported by the Foundation for Excellent Young Scholars of Hunan Scientific Committee,ChinaProject(116001)supported by the Consultative Program of the Chinese Academy of Engineering+1 种基金Project(11JJ6040)supported by the National Natural Science Foundation of Hunan Province,ChinaProject(2010GK3198)supported by the Science and Research Program of Hunan Province,China
文摘Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results.
文摘Background:Familiarity with a simulation platform can seduce modellers into accepting untested assumptions for convenience of implementation.These assumptions may have consequences greater than commonly suspected,and it is important that modellers remain mindful of assumptions and remain diligent with sensitivity testing.Methods:Familiarity with a technique can lead to complacency,and alternative approaches and software can reveal untested assumptions.Visual modelling environments based on system dynamics may help to make critical assumptions more evident by offering an accessible visual overview and empowering a focus on representational rather than computational efficiency.This capacity is illustrated using a cohort-based forest growth model developed for mixed species forest.Results:The alternative model implementation revealed that untested assumptions in the original model could have substantial influence on simulated outcomes.Conclusions:An important implication is that modellers should remain conscious of all assumptions,consider alternative implementations that reveal assumptions more clearly,and conduct sensitivity tests to inform decisions.
基金Supported by the National Natural Science Foundation of China(61173151,61472309)
文摘Inspired by the framework of Boyen, in this paper, an attribute-based signature（ABS） scheme from lattice assumption is proposed. In this attribute-based signature scheme, an entity＇s attributes set corresponds to the concatenation of a lattice matrix with the sum of some random matrices, and the signature vector is generated by using the Preimage Sampling algorithm. Compared with current attribute-based signature schemes, this scheme can resist quantum attacks and enjoy shorter public-key, smaller signature size and higher efficiency.
文摘Mechanisms of animal learning and memory were traditionally studied without reference to niche-specific functional considerations. More recently, ecological demands have informed such investigations, most notably with respect to foraging in birds. In parallel, behavioural ecologists, primarily concerned with functional optimization, have begun to consider the role of mechanistic factors, including cognition, to explain apparent deviations from optimal predictions. In the present paper we discuss the application of laboratory-based constructs and paradigms of cognition to the real-world challenges faced by avian foragers. We argue that such applications have been handicapped by what we term the ＇paradigmatic assumption＇ - the assumption that a given laboratory paradigm maps well enough onto a congruent cognitive mechanism （or cognitive ability） to justify confiation of the two. We present evidence against the paradigmatic assumption and suggest that to achieve a profitable integration between function and mechanism, with respect to animal cognition, a new conceptualization of cognitive mechanisms - functional cogni- tion - is required. This new conceptualization should define cognitive mechanisms based on the informational properties of the animal＇s environment and the adaptive challenges faced. Cognitive mechanisms must be examined in settings that mimic the im- portant aspects of the natural environment, using customized tasks designed to probe defined aspects of the mechanisms＇ opera- tion. We suggest that this approach will facilitate investigations of the functional and evolutionary relevance of cognitive mecha- nisms, as well as the patterns of divergence, convergence and specialization of cognitive mechanisms within and between species .
文摘The distribution of shear stress on the cross-section of plastic metal solid circular shaft under pure torsion yielding, the applicability of complete plastic model assumption and the shear stress formula were researched. Based on the shear stress formula of circular shaft under pure torsion in elastic stage, the formula of torque in elastic stage and the definition of yield, it is obtained that the yielding stage of plastic metal shaft under pure torsion is only a surface phenomenon of torque-torsion angle relationship, and the distribution of shear stress is essentially different from that of tensile stress when yielding under uniaxial tension. The pure torsion platform-torsion angle and the shape of torque-torsion angle curve cannot change the distribution of shear stress on the shaft cross-section. The distribution of shear stress is still linear with the maximum shear stress ts. The complete plasticity model assumption is not in accordance with the actual situation of shaft under torsion. The experimental strength data of nine plastic metals are consistent with the calculated results of the new limiting strain energy strength theory （LSEST）. The traditional yield stress formula for plastic shaft under torsion is reasonable. The shear stress formula based on the plane assumption in material mechanics is applicable for all loaded stages of torsion shaft.
文摘The article is devoted to hitherto never undertaken applying an almost unknown logically formalized axiomatic epistemology-and-axiology system called “Sigma-V” to the Third Newton’s Law of mechanics. The author has continued investigating the extraordinary (paradigm-breaking) hypothesis of formal-axiological interpreting Newton’s mathematical principles of natural philosophy and, thus, has arrived to discrete mathematical modeling a system of formal axiology of nature by extracting and systematical studying its proper algebraic aspect. Along with the proper algebraic machinery, the axiomatic (hypothetic-deductive) method is exploited in this investigation systematically. The research results are the followings. 1) The Third Newton’s Law of mechanics has been modeled by a formal-axiological equation of two-valued algebraic system of metaphysics as formal axiology. (Precise defining the algebraic system is provided.) The formal-axiological equation has been established (and examined) in this algebraic system by accurate computing compositions of relevant evaluation-functions. Precise tabular definitions of the evaluation-functions are given. 2) The wonderful formula representing the Third Newton’s Law (in the relevant physical interpretation of the formal theory Sigma-V) has been derived logically in Sigma-V from the presumption of a-priori-ness of knowledge. A precise axiomatic definition of the nontrivial notion “a-priori-ness of knowledge” is given. The formal derivation is implemented in strict accordance with the rigor standard of D. Hilbert’s formalism;hence, checking the formal derivation submitted in this article is not a difficult task. With respect to proper theoretical physics, the formal inference is a nontrivial scientific novelty which has not been discussed and published elsewhere yet.
基金supported by the National Science and Technology Major Project,China(No.2017-II-0009-0023)China’s 111 project(No.B17037)sponsored by Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China.
文摘This paper presents a thorough study of the effect of the Constant Eddy Viscosity(CEV)assumption on the optimization of a discrete adjoint-based design optimization system.First,the algorithms of the adjoint methods with and without the CEV assumption are presented,followed by a discussion of the two methods’solution stability.Second,the sensitivity accuracy,adjoint solution stability,and Root Mean Square(RMS)residual convergence rates at both design and offdesign operating points are compared between the CEV and full viscosity adjoint methods in detail.Finally,a multi-point steady aerodynamic and a multi-objective unsteady aerodynamic and aeroelastic coupled design optimizations are performed to study the impact of the CEV assumption on optimization.Two gradient-based optimizers,the Sequential Least-Square Quadratic Programming(SLSQP)method and Steepest Descent Method(SDM)are respectively used to draw a firm conclusion.The results from the transonic NASA Rotor 67 show that the CEV assumption can deteriorate RMS residual convergence rates and even lead to solution instability,especially at a near stall point.Compared with the steady cases,the effect of the CEV assumption on unsteady sensitivity accuracy is much stronger.Nevertheless,the CEV adjoint solver is still capable of achieving optimization goals to some extent,particularly if the flow under consideration is benign.
文摘This study is focused on the mineralogical and chemical compositions,deposition environment and mechanism of formation of sediments of Kyzyltokoy basin.By an interpretation of formation,an environment of sedimentation of a basin was separated into three general conditions:a condition where glauconitization process interrupted,where process reached a completion and where occurred decay of glauconites,i.e.,the beginning and interruption in the middle of glauconitization,completion of the
基金Supported by the National Natural Science Foundation of China(No.69772035,69882002) and "863" Programme
文摘Recently, many bit commitment schemes have been presented. This paper presents a new practical bit commitment scheme based on Schnorr's one-time knowledge proof scheme,where the use of cut-and-choose method and many random exam candidates in the protocols are replaced by a single challenge number. Therefore the proposed bit commitment scheme is more efficient and practical than the previous schemes In addition, the security of the proposed scheme under factoring assumption is proved, thus the cryptographic basis of the proposed scheme is clarified.
