遵义地方生态智慧与绿色空间形塑过程研究

遵义作为国务院在1982年首批公布的全国24个历史文化名城之一,其历史文化底蕴深厚且自然资源丰富,“城中有山,山中有城,山水相映”的景观特色是当地历代先民在生息繁衍过程中与自然环境不断适应协调的集中体现,也是各个时期价值观念、社会制度、地方文化影响下绿色空间与建设空间层层累积的产物。以遵义市志、府志、城建志、图志及历史地图等为主要数据来源,借助空间信息图示转译的手段,将历史信息与现状遗存进行互证,对纵向时间轴上经历代人居环境建设实践累积而成的绿色空间形塑过程进行阶段性划分,进而在横向时间切片上分析不同阶段人工与自然的相互作用,全面阐述在山地民族特性、庄园经济发展、区域景观营建、交通条件改善、城市规划调控等多种驱动力下绿色空间的形塑过程,以及在人工与自然联动机制中涌现出的地方生态智慧。

跨国网络视角下善堂的形塑过程与特征

明清以降,以善会善堂为主要形态的民间慈善组织实施有效的慈善救济,与政府的社会福利职责形成功能互补,稳定社会秩序。在国家与社会强弱关系变化中,慈善与宗教信仰并重的潮汕善堂形成海内外并行的两条轨迹,构建了跨国的潮人善堂网络,但是目前多数研究忽略了形塑过程中地方政府取缔反动会道门活动,并将大峰祖师信仰视为封建迷信致使善堂活动沉寂的环节。因此,本文运用史料与田野调查梳理潮人善堂海内外并行的跨国网络形塑过程,关注形塑过程中发端、普及、海外流传、危机、沉寂及复兴等环节。研究发现,在社会救济公共领域,善堂通过应对危机的经验积累和海外华侨华人与侨乡联系的变化,呈现出显著的慈善性、民间性、宗教性与跨国性特征;在社会与国家互补对立的动态演变中,社会与国家最终寻求建立一种良性的积极互动关系,这对研究中国近代慈善事业与福利组织发展有重要的启示意义。

时空视野下桂林山水园林形塑过程与机理

桂林山水园林是喀斯特地貌下区域风景营建的优秀代表,体现着城市、人与风景要素协调共生的人居理念。通过古代文献解读与地理时空分析,探究在人文与自然联动作用下桂林山水园林形塑的时空过程与内在机理。研究表明:1)桂林山水园林依托于具有喀斯特地貌特征的独特风景基底而建设,营建数量和规模由唐至清持续增长,宋元为营建高峰;园林类型随时间逐渐丰富完善,公共园林长期占据主导地位;2)桂林山水园林的形塑过程在时间上可分为由山水到园林的初步建构(唐至宋元)和园林体系的完善(明清)2个阶段,最终形成了类型多样、风格鲜明的地域园林体系。在空间上,从散点式发展逐渐转化为城景相融一体化发展,形塑出桂林城园一体的风景面貌;3)山水环境支撑、政治经济影响、城市建设发展及游赏文化助推4方面的综合驱动作用,塑造了具有真山真水、类型多元、城景相融、开放共享等显著特征的桂林喀斯特区域风景园林系统。研究有利于促进区域风景特征的保护与文化传承,并对当代山水城市景观塑造具有一定参考意义。

Effects of process parameters on warpage of rapid heat cycle moulding plastic part

The effects of process parameters in rapid heat cycle moulding （RHCM） on parts warpage were investigated. A vehicle-used blue-tooth front shell （consisting of ABS material） was considered as a part example manufactured by RHCM method. The corresponding rapid heat response mould with an innovational conformal heating/cooling channel system and a dynamic mould temperature control system based on the Jll-W-160 type precise temperature controller was proposed. During heating/cooling process, the mould was able to be heated from room temperature to 160 ~C in 6 s and then cooled to 80 ~C in 22 s. The effects of processing conditions in RHCM on part warpage were investigated based on the single factor experimental method and Taguchi theory. Results reveal that the elevated mould temperature reduces unwanted freezing during the injection stage, thus improving mouldability and enhancing part quality, whereas the overheated of mould temperature will lead to defective product. The feasible mould temperature scope in RHCM should be no higher than 140 ~C, and the efficient mould temperature scope should be around the polymer heat distortion temperature. Melt temperature as well as injection pressure effects on warpage can be divided into two stages The lower stage gives a no explicit effect on warpage whereas the higher stage leads to a quasi-linear downtrend. But others affect the warpage as a V-type fluctuation, reaching to the minimum around the heat distortion temperature. Under the same mould temperature condition, the effects of process parameters on warpage decrease according to the following order, packing time, packing pressure, melt temperature, injection pressure and cooling time, respectively.

Nosing process of empty and foam-filled circular metal tubes on semispherical die by theoretical and experimental investigations

Nosing process of circular metal tubes in empty and polyurethane foam-filled conditions on a semispherical rigid die was analyzed by theoretical and experimental methods.A new theoretical model of plastic deformation of circular metal tubes was demonstrated during the nosing process on a rigid semispherical die.Based on the analytical model,some theoretical relations were calculated to estimate instantaneous forming load and dissipated energy of empty and foam-filled circular metal tubes versus axial displacement.Some circular brazen and aluminum tubes were prepared and shaped into semispherical nosed nozzles to verify the present theory.Comparison of theoretical predictions and the corresponding experimental measurements reveals that predicted load?displacement and dissipated energy?displacement diagrams by theoretical formulas have a good correlation with the corresponding experimental curves and it proves verity of the theory.Also,the present theory shows that dissipated energy and axial load of empty tubes depend on material type,wall thickness and diameter of the tubes and they are independent of tube initial length.Furthermore,the experimental results show that the presence of polyethylene Teflon-constraints increases ultimate axial displacement of the forming process.

Elastoplastic model for discontinuous shear deformation of deep rock mass

Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechanism,the complete deformation process of deep rock mass,with a great emphasis on local shear deformation stage,was analyzed in detail.The quasi continuous shear deformation of the deep rock mass is described by a combination of smooth functions:the averaged distribution of the original deformation field,and the local discontinuities along the slip lines.Hence,an elasto-plastic model is established for the shear deformation process,in which the rotational displacement is taken into account as well as the translational component.Numerical analysis method was developed for case study.Deformation process of a tunnel under high earth stress was investigated for verification.

Plastic deformation behavior of Mg97Zn1Y2 extruded alloys

The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic tension-compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 （molar fraction, %）, which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1 Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.

Simulation of bulk metal forming processes using one-step finite element approach based on deformation theory of plasticity

The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.

A relative permeability model for deformable soils and its impact on coupled unsaturated flow and elasto-plastic deformation processes.

Relative permeability is an indispensable property for characterizing the unsaturated flow and induced deformation in soils. The widely used Mualem model is inadequate for deformable soils because of its assumption of a rigid pore structure and the resultant unique dependence of the tortuosity factor on the volumetric water content. In this study, a unified relationship between the relative permeability and the effective degree of saturation was proposed for deformable soils by incorporating our newly developed water retention curve model into the original Mualem model, in which a new tortuosity factor was defined using the fractal dimension of flow paths and the mean radius of water-filled pores for representing the effect of pore structure variation. The modified deformation-dependent relative permeability model was verified using test data on five types of soils; the verification revealed a much better performance of the proposed model than the original model, which commonly overestimates the relative permeability of deformable soils. Finally, the proposed model was implemented in a coupled numerical model for examining the unsaturated flow and elastoplastic deformation processes in a soil slope induced by rain infiltration. The numerical results showed that the deformation-dependent nature of relative permeability has a remarkable effect on the elastoplastic deformation in the slope and that neglect of the deformation-dependent behavior of relative permeability causes overestimation of the depth of failure.

A New Model for Simulation of Cold Roll-Forming of Tubes by Using Spline Finite Strip Method

A new model,called object model,for the simulation of cold roll-forming of tubes is presented.The model inherits the advantages of old models and is the embodiment of forming process that the strip is rolled step by step from feed rollers to last rolling pass.The elastic-plastic large deformation spline finite strip method based on updated Lagrangian method has been developed by improving the stiffness and transition matrix.Combined theory formulas and new analytical model,the forming process of a tube has been simulated successfully as an example.The analytical results are submitted and indicate that the proposed simulation method and new model are applicable.