模态理性论的双重两难

模态理性论是模态认识论领域占主导地位的主流理论。它在哲学各分支领域,如心灵哲学和形而上学的应用也非常广泛。本文有两个目的:(1)通过梳理模态理性论的理论建构,本文将揭示该理论面临双重两难。(2)本文将指出,学者们在应用模态理性论时往往忽视了这两个两难。对两难的忽视导致模态理性论在哲学各分支领域的应用存在走弯路和误用的现象。

ENHANCED UNSTEADY AND NONLINEAR ROTOR WAKE MODEL FOR REAL-TIME FLIG HT SIMULATION

WT5 'BZThis paper presents an unsteady and nonlinear wake model based on th e widely used Peters He finite state dynamic wake model with improvements. The swirl component in the tip trace plane (TTP) can be predicted, nonlinear items are added into the linear theory, and the old small angle assumption use d in matrix prediction is removed. All of these enha ncements are aimed at the low speed flight phase and formulations for the induce d velocity field just in the TTP frame are derived. The corresponding FORTRAN pr ogram is tested and optimized for the real time applications on PCs.

模态与本质:先验的模态本质主义知识论——以洛的严肃本质主义知识论为例

本质主义在近几年模态知识论的讨论中得到了大量的关注和认可。继法恩对本质的模态性解释路径提出挑战之后,学界起了新亚里士多德式的本质主义的新浪潮。洛提出了一种先验的严肃本质主义,他认为我们可以凭借对给定事物的真实定义的理解而把握到该事物的本质,然后再依据桥律(□xP→□P)我们就可获得模态知识。我们认为,面对自然类事物的模态探讨时,运用纯粹的先验方法总会顾此而失彼,而采用一种混合式的分析进路将会是未来探讨如何获得模态知识的主要趋势。

A theoretical model for assessing the sustainability of ecosystem services

The Value of the World＇s Ecosystem Services and Natural Capital by Costanza in 1997 is generally regarded as a monumem for the research of valuing ecosystem services. However, the classification of ecosystem services, the method of various services summation and the purpose for static global value had be confronted by many criticisms. Based on the summary of these criticisms, suggestions, related function assessment and further study direction, the sustainability of ecosystem Services is presented. The two basic indicators in ecology, productivity and biodiversity, respectively charactering the ability of producing and self-organizing, not only represent the internal function of ecosystem, but also are proportioned to its external function of supporting and providing for human life. On presenting the general.form of ecosystem services assessment, this paper improves the mathematical formula by giving a function adjusting coefficient composea of productivity and biodiversity. Theoretically, the integration of the two indicators reflects the changes of ecosystem services at spatial and temporal scales, can physically assess the sustainability of ecosystem services, and build a firm scientific fundament of value assessment for ecosystem services. Objectively, its application should be strictly tested in next step.

Fuzzy robust sliding mode control of a class of uncertain systems

Aiming at a class of systems under parameter perturbations and unknown external disturbances, a method of fuzzy robust sliding mode control was proposed. Firstly, an integral sliding mode surface containing state feedback item was designed based on robust H∞ control theory. The robust state feedback control was utilized to substitute for the equivalent control of the traditional sliding mode control. Thus the robustness of systems sliding mode motion was improved even the initial states were unknown. Furthermore, when the upper bound of disturbance was unknown, the switching control logic was difficult to design, and the drawbacks of chattering in sliding mode control should also be considered simultaneously. To solve the above-mentioned problems, the fuzzy nonlinear method was applied to approximate the switching control term. Based on the Lyapunov stability theory, the parameter adaptive law which could guarantee the system stability was devised. The proposed control strategy could reduce the system chattering effectively. And the control input would not switch sharply, which improved the practicality of the sliding mode controller. Finally, simulation was conducted on system with parameter perturbations and unknown external disturbances. The result shows that the proposed method could enhance the approaching motion performance effectively. The chattering phenomenon is weakened, and the system possesses stronger robustness against parameter perturbations and external disturbances.

Ecological suitability evaluation for urban growth boundary in red soil hilly areas based on fuzzy theory

The fuzziness exists in spatial distribution of geographic data of land suitability evaluation processes,which makes it difficult to quantify land boundaries by using traditional binary logic-based overlay model.Aiming at this limitation,an ecological suitability evaluation analysis model was presented based on fuzzy theory and a research on urban growth boundary(UGB) of the Great-Hexi Leading District(GHLD) of Changsha was conducted.With the support of GIS,RS and MATLAB,slope,elevation,vegetation,soil productivity,soil permeability,water body and land use are selected as the input of model according to the characteristic properties of soil and terrain in red soil hilly areas.The running result of this model indicates that the ratios of highly suitable land,suitable land,moderately suitable land and unsuitable land in GHLD are 18.75%,10.31%,64.16%,6.78%,respectively.This result accords with spatial structure worked out by Space Development Strategy Planning of GHLD,Based on this result,several suggestions are made to guide UGB developments in future.

模态经验论的两难困境——以罗卡洛斯的相似性理论为例

关于“我们如何获得关于可能性的知识?”这个问题,模态知识论领域一向有理性论和经验论的二分。模态理性论者认为可能性知识来自于先天设想;模态经验论者认为可能性知识来自于后天经验。理性论长期占据主流地位,并被广泛应用于其它领域。但是,学界发现理性论面临两难困境:要么遭遇反例;要么解释范围过窄。理性论的两难引发了模态知识论领域的经验论转向。经验论路径下最受瞩目的理论是罗卡洛斯的相似性理论。然而,以相似性理论为例,本文将指出,经验论面临和理性论类似的两难困境。进一步,本文将论证,经验论的困境更糟糕:它比理性论的解释范围更窄。最后,本文将阐述经验论和理性论解释范围有如此差别的根源,并展望一种融合理性论和经验论的新模态认知理论。

Quantization of black hole entropy from unstable circular null geodesics

The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassically construct the entropy spectrum of the static and stationary black holes from the null geodesics. The result shows that the spacing of the entropy spectrum only depends on the property of the black hole in the eikonal limit. Moreover, for a black hole far from the extremal case, the spacing is found to be smaller than 2π for any dimension, which is very different from the result of the previous work by using the usual quasinormal mode frequencies.

Turing patterns in a reaction-diffusion epidemic model

In this paper, we investigate the spatiotemporal dynamics of a reactio^diffusion epi- demic model with zero-flux boundary conditions. The value of our study lies in two aspects： mathematically, by using maximum principle and the linearized stability theory, a priori estimates of the steady state system and the local asymptotic stability of positive constant solution are given. By using the implicit function theorem, the exis- tence and nonexistence of nonconstant positive steady states are shown. Applying the bifurcation theory, the global bifurcation structure of nonconstant positive steady states is established. Epidemiologically, through numerical simulations, under the conditions of the existence of nonconstant positive steady states, we find that the smaller the space, the easier the pattern formation; the bigger the diffusion, the easier the pattern formation. These results are beneficial to disease control, that is, we must do our best to control the diffusion of the infectious to avoid disease outbreak.