基于共生原理的3D打印技术种群竞合演化机理分析

基于共生原理、Logistic模型和进化博弈原理解析了3D打印技术种群的竞合演化机理,从技术进化视角揭示了3D打印技术创新的内在原理与发展规律。所得结论如下:当两种3D打印技术处于纯竞争性或替代性大于互补性的情境下时,不具有竞争优势的3D打印技术种群将会最终消亡;当两种3D打印技术处于纯互补性或替代性小于互补性的情境下时,两种3D打印技术种群都能在合作共生下获得更大的生存空间。

理性权衡即兴行为视角下的企业竞合关系:基本逻辑、演化机理及其治理

竞合关系体现在竞合演化和竞合治理之中。竞合关系的演化贯穿于企业内外部环境的变化过程中,竞合即兴行为的演化机理为:企业内外部环境的变化诱发了企业的即兴行为,完全理性下的竞合规则决定了即兴行为,有限理性下的竞合规范指导了即兴行为;在三种作用力下,竞合行为不断演化,完全理性与有限理性的权衡使得竞合行为满足阶段性与长期性决策的目标。竞合关系治理在于保障理性权衡的竞合即兴行为能够高质量地执行和存续,其治理结构选择为弹性联盟。通过对苹果和三星竞合案例分析,从实证层面验证了所构建的竞合理论的研究框架。

秦岭三叠系特提斯型沉积与“开-合”演化

秦岭三叠系为东—西向带状展布,与南、北两侧的前三叠系以区域性断裂为界。西宽东窄楔形向东尖灭,向西与巴颜喀喇特提斯复理石建造相连,建造类型独特,以深水相重力流、崩塌堆积、滑混堆积、浊流沉积为主,厚度巨大。塑性流变、纵弯褶皱普遍发育,形变程度显著高于与其比邻的前三叠系,具有裂陷槽沉积和演化特征。裂陷槽裂"开"于中三叠世,"合"于中三叠世晚期—晚三叠世早期。秦岭三叠系特提斯型建造显著有别于中国扬子型台地相三叠系建造,记录了一个环境相对独立、应变域特殊、"开-合"演化旋回完整的构造事件。

基于生态位的畜牧业商业生态系统中企业演化博弈分析

随着绿色生态与可持续发展理念的深入,我国畜牧业朝着产业竞争的高级形式(商业生态系统)演变已成为必然。笔者运用演化博弈对畜牧业商业生态系统中位于重叠生态位的企业进行了竞合博弈分析,对不同生态位的企业进行了合作博弈分析。在此基础上,分析了两种情境下的企业演化均衡过程,最后提出了对策建议。

Simultaneous Identification of Thermophysical Properties of Semitransparent Media Using a Hybrid Model Based on Artificial Neural Network and Evolutionary Algorithm

A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductivity and effective absorption coefficient of semitransparent materials.For the direct model,the spherical harmonic method and the finite volume method are used to solve the coupled conduction-radiation heat transfer problem in an absorbing,emitting,and non-scattering 2D axisymmetric gray medium in the background of laser flash method.For the identification part,firstly,the temperature field and the incident radiation field in different positions are chosen as observables.Then,a traditional identification model based on PSO algorithm is established.Finally,multilayer ANNs are built to fit and replace the direct model in the traditional identification model to speed up the identification process.The results show that compared with the traditional identification model,the time cost of the hybrid identification model is reduced by about 1 000 times.Besides,the hybrid identification model remains a high level of accuracy even with measurement errors.

基于竞合关系演化的中国集成电路本土企业市场渗透率

文章从企业更替频率、技术更新速度和企业地理集中度三个维度,分析2000—2018年中国集成电路本土企业间的竞争合作(竞合)关系及其演变过程,在此基础上构建市场渗透率模型,探究三种经营模式企业的市场渗透率发展态势及空间关联。结果表明:①三种经营模式的企业在“竞合平衡建立—平衡破坏”的动态过程中表现出不同的周期性规律,其中企业更替频率对“设计+销售”型企业的竞合关系变化起着主导作用,同时也是维持“设计+生产+销售”型企业竞合关系平缓发展的关键,而技术更新速度在推动“生产代工”型企业向新竞合平衡演进时有着明显的倒“U”型效应。②随着竞合关系演变,集成电路“设计+销售”型企业在设计环节的市场渗透率、“生产代工”型企业在制造环节的市场渗透率均增长明显,两者相互配合的代工模式大大削弱了“设计+生产+销售”型企业的市场竞争力。③2000—2008年三类企业的市场渗透率在空间上具有显著的正向依赖关系,2009年后低—高、高—低异类集聚比例上升,空间组合不断向随机和离散分布演化。

Effect of solution treatment and aging on microstructural evolution and mechanical behavior of NiTi shape memory alloy

As-received nickel-titanium （NiTi） shape memory alloy with a nominal composition of Ni50.9Ti49.1 （mole fraction,%） was subjected to solution treatment at 1123 K for 2 h and subsequent aging for 2 h at 573 K, 723 K and 873 K, respectively. The influence of solution treatment and aging on microstructural evolution and mechanical behavior of NiTi alloy was systematically investigated by transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, scanning electron microscopy （SEM） and compression test. Solution treatment contributes to eliminating the Ti2Ni phase in the as-received NiTi sample, in which the TiC phase is unable to be removed. Solution treatment leads to ordered domain of atomic arrangement in NiTi alloy. In all the aged NiTi samples, the Ni4Ti3 precipitates, the R phase and the B2 austenite coexist in the NiTi matrix at room temperature, while the martensitic twins can be observed in the NiTi samples aged at 873 K. In the NiTi samples aged at 573 and 723 K, the fine and dense Ni4Ti3 precipitates distribute uniformly in the NiTi matrix, and thus they are coherent with the B2 matrix. However, in the NiTi sample aged at 873 K, the Ni4Ti3 precipitates exhibit the very inhomogeneous size, and they are coherent, semi-coherent and incoherent with the B2 matrix. In the case of aging at 723 K, the NiTi sample exhibits the maximum yield strength, where the fine and homogeneous Ni4Ti3 precipitates act as the effective obstacles against the dislocation motion, which results in the maximum critical resolved shear stress for dislocation slip.

重器功能,合礼演化——从金石乐悬到本品鼓吹

本文以周公制礼作乐使礼乐制度彰显为前提,将两周时期之礼器分为有声礼器和无声礼器两大类。对两周时期各级有身份人士依制普适性拥有金石乐悬领衔的礼乐重器,该类礼乐器在多功能使用过程中不断内部扩充的意义进行辨析,观察其优势与局限,金石乐悬并非因战国所谓礼崩乐坏而缺失,实属汉唐礼制的制定者将其回归于"国之大事"中使用。文章把握金石乐悬汉唐宫廷小众化发展脉络,宋至清又因祀孔而达县治的过程;与此同时将目光投向另外一种彰显文武各级官员身份的礼乐重器鼓吹乐队组合及其承载,论证转型扩展中有声礼器的丰富性意义。作为军中走出的鼓吹在国家意义进入礼乐体制之后不断扩展其使用功能,从激励鼓舞到威仪警严,从卤簿仪仗到太常、教坊,既呈喧阗震慑,又有"乐"之侧重,渐呈体系化特征。自汉魏以降呈现金石乐悬为代表的"华夏正声"乐队小众化使用,军旅、宫廷与各级官府"胡汉杂陈"鼓吹乐普适性存在,两者并置承载礼乐重器功能。

Microstructural evolution of Al-0.66Mg-0.85Si alloy during homogenization

The microstructural evolution of Al-0.66Mg-0.85Si alloy was investigated by optical microscopy （OM）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and differential scanning calorimetry （DSC）. The as-cast microstructure is typical dendritical structure, consisting of α（Al）, Al（FeMn）Si, Mg2Si, AlCuMgSi and Si phases. The electron diffraction analyses indicate that the Al（FeMn）Si phase is Al15（FeMn）3Si2 and the AlCuMgSi phase is Q（Al1.9CuMg4.1Si3.3）. There are two kinds of Mg2Si phases in the as-cast microstructure. One is formed in the casting process, and the other is formed in the cooling process after casting process is finished. The phases have different crystal structures. After homogenization treatment at 545 ℃ for 20 h, Mg2Si, Si and Q intermetallic compounds are dissolved into matrix completely, and the remaining phases are α（Al） and Al15（FeMn）3Si2. The size of Al15（FeMn）3Si2 phase is decreased, and the phase is spheroidized and distributes along grain boundary discontinuously. The Zn-containing phases are not found during solidification and homogenization process.

Microstructural stability of long term aging treated Ti-22Al-26Nb-1Zr orthorhombic titanium aluminide

The microstructure development of lamellar structure of an orthorhombic Ti2AlNb-based Ti？22Al？26Nb？1Zr alloy, includingB2 decomposition and spheroidization ofO phase, was investigated. The results show that the lamellar structure is fabricated by heating the samples in the singleB2 phase field and cooling slowly in the furnace. Aging treatments are conducted in the （O＋B2） phases field by air cooling. After aging at 700 °C for a short time within 100 h, there is no significant change of microstructures, whereas the coarsening of lamellae is observed in the long-term aged microstructure. Ti？22Al？26Nb？1Zr alloy exhibits microstructural instability including the severe dissolution ofB2 lamella, discontinuous precipitation and spheroidization of O phase during the long term aging process at 700 °C up to 800 h. In addition, a pronounced formation of branch-shapedO phase lamella is observed for the alloy aged over 100 h.

Phase-field study on competition precipitation process of Ni-Al-V alloy

With microscopic phase-field kinetic model, atomic-scale computer simulation program for the precipitation sequence and microstructure evolution of the ordered intermetallic compound γ＇ and θ in ternary Ni75AlxV25-x alloy were studied. The simulation results show that Al concentration has important effects on the precipitation sequence. When Al concentration in Ni75AlxV25-x alloy is low, 0（Ni3V） ordered phase will be firstly precipitated, followed by γ＇（Ni3Al） ordered phase. With Al concentration increasing, θ and γ＇ ordered phases are simultaneously precipitated. With A1 concentration further increasing, γ＇ ordered phase is firstly precipitated, followed by θ ordered phase. There is a competition relationship between θ and γ＇ ordered phases during growth and coarsening process. No matter which first precipitates, θ ordered phase always occupies advantage in the competition process of coarsening, thus, the microstructure with preferred orientation is formed.

Effect of homogenization treatment on microstructure and mechanical properties of DC cast 7X50 aluminum alloy

The evolution of the eutectic structures in the as-cast and homogenized 7X50 aluminum alloys was studied by scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy dispersive spectrometer(EDS), differential scanning calorimetry(DSC), X-ray diffraction(XRD) and tensile test. The results show that the main phases are S(Al2CuMg), T(Al2Mg3Zn3) and Mg Zn2, with a small amount of Al7Cu2 Fe and Al3 Zr in the as-cast 7X50 alloy. The volume fraction of the dendritic-network structure and residual phase decreases gradually during the homogenization. After homogenization at 470 °C for 24 h and then 482 °C for 12 h, the T(Al2Mg3Zn3) phase disappears and minimal S(Al2CuMg) phase remains, while almost no change has happened for Al7Cu2 Fe. There is a strong endothermic peak at 477.8 °C in the DSC curve of as-cast alloy. A new endothermic peak appears at 487.5 °C for the sample homogenized at 470 °C for 1 h. However, this endothermic peak disappears after being homogenized at 482 °C for 24 h. The T(Al2Mg3Zn3) phase cannot be observed by XRD, which is consistent with that T phase is the associated one of S(Al2CuMg) phase and Mg Zn2 phase. The volume fraction of recrystallized grains is substantially less in the plate with pre-homogenization treatment. The strength and fracture toughness of the plate with pre-homogenization treatment are about 15 MPa and 3.3 MPa·m1/2 higher than those of the material with conventional homogenization treatment.

Microstructural evolution of Mg, Ag and Zn micro-alloyed Al-Cu-Li alloy during homogenization

The microstructural evolution of a Mg, Ag and Zn micro-alloyed Al?3.8Cu?1.28Li (mass fraction, %) alloy ingot during two-step homogenization was examined in detail by optical microscopy (OM), differential scanning calorimetry (DSC), electron probe micro-analysis (EPMA) and X-ray diffraction (XRD) methods. The results show that severe dendritic segregation exists in the as-cast ingot. There are many secondary phases, includingTB(Al7Cu4Li),θ(Al2Cu),R(Al5CuLi3) andS(Al2CuMg) phases, and a small amount of (Mg+Ag+Zn)-containing and AlCuFeMn phases. The fractions of intermetallic phases decrease sharply after 2 h of second-step homogenization. By prolonging the second-step homogenization time, theTB,θ,R,S and (Mg+Ag+Zn)-containing phases completely dissolve into the matrix. The dendritic segregation is eliminated, and the homogenization kinetics can be described by a constitutive equation in exponential function. However, it seems that the AlCuFeMn phase is separated into Al7Cu2Fe and AlCuMn phases, and the size of Al7Cu2Fe phase exhibits nearly no change when the second-step homogenization time is longer than 2 h.

Interfacial characteristics and microstructural evolution of Sn-6.5Zn solder/Cu substrate joints during aging

The influence of isothermal aging at 150 °C on the microstructural characteristics and microhardness of the Sn-6.5Zn solder/Cu joint was studied. The mechanisms for the formation and evolution of intermetallic compound （IMC） at the interface of the Sn-6.5Zn/Cu joint were also analyzed. The results indicate that a continuous layer consisting of CuZn and Cu5Zn8 IMCs is formed in the interface zone. As the aging time prolongs, the thickness of the IMC layer first increases and then decreases, and the continuous and compactable layer is destroyed due to the decomposition of the Cu-Zn IMC layer. A discontinuous layer of Cu6Sn5 IMC is present within the Cu substrate near the decomposed region. The interface becomes rough and evident voids form after aging. The microhardness of the interface increases owing to the application of aging.

Creep properties and microstructure evolution of nickel-based single crystal superalloy at different conditions

The creep properties of nickel-based single crystal superalloy with [001] orientation was investigated at different test conditions. The microstructure evolution of γ′ phase, TCP phase and dislocation characteristic after creep rupture was studied by SEM and TEM. The results show that the alloy has excellent creep properties. Two different types of creep behavior can be shown in the creep curves. The primary creep is characterized by the high amplitude at test conditions of (760 °C, 600 MPa) and (850 °C, 550 MPa) and the primary creep strain is limited at (980 °C, 250 MPa), (1100 °C, 140 MPa) and (1120 °C, 120 MPa). A little change ofγ′precipitate morphology occurs at (760 °C, 600 MPa). The lateral merging of the γ′ precipitate has already begun at (850 °C, 550 MPa). Theγphase is surrounded by theγ′phase at (980 °C, 250 MPa). Theγphase is no longer continuous tested at (1070 °C, 140 MPa). At (1100 °C, 120 MPa), the thickness ofγphase continues to increase. No TCP phase precipitates in the specimens at (760 °C, 600 MPa), (850 °C, 550 MPa) and (980 °C, 250 MPa). Needle shaped TCP phase precipitates in the specimens tested at (1070 °C, 140 MPa) and (1100 °C, 120 MPa). The dislocation shear mechanism including stacking fault formation is operative at lower temperature and high stress. The dislocation by-passing mechanism occurs to form networks atγ/γ′interface under the condition of high temperature and lower stress.

Microstructural evolution of ultra-high strength Al-Zn-Cu-Mg-Zr alloy containing Sc during homogenization

The microstructural evolution and composition distribution of an Al-Zn-Cu-Mg-Sc-Zr alloy during homogenization were investigated by optical microscopy（OM）,scanning electron microscopy（SEM）,energy dispersive spectrometry（EDS）,X-ray diffraction（XRD） and differential scanning calorimetry（DSC）.The results show that severe dendritic segregation exists in Al-Zn-Cu-Mg-Sc-Zr alloy ingot.There are a lot of eutectic phases at grain boundary and the distribution of the main elements varies periodically along interdendritic region.The main eutectic phases at grain boundary are Al7Cu2Fe phase and T（Al2Mg3Zn3）.The residual phases are dissolved into the matrix gradually during homogenization with increasing temperature and prolonging holding time,which can be described by a constitutive equation in exponential function.The overburnt temperature of the alloy is 473.9 ℃.The optimum parameters of homogenization are 470 ℃ and 24 h,which is consistent with the result of homogenization kinetic analysis.

Microstructure evolution and deformation features of single crystal nickel-based superalloy containing 4.2% Re during creep

By means of microstructure observation and measurement of creep properties,the high temperature creep behaviors of a single crystal nickel-based superalloy containing Re were investigated.Results show that the single crystal nickel-based superalloy containing 4.2% Re possesses a better creep resistance at high temperature.After being crept up to fracture,the various morphologies are displayed in the different areas of the sample,and the γ＇ phase is transformed into the rafted structure along the direction vertical to the applied stress axis in the regions far from the fracture.But the coarsening and twisting extents of the rafted γ＇ phase increase in the regions near the fracture,which is attributed to the occurrence of the larger plastic deformation.In the later stage of creep,the deformation mechanism of the alloy is that the dislocations with [01^-1]and [011] trace features shear into the rafted γ＇ phase.The main/secondary slipping dislocations are alternately activated to twist the rafted γ＇ phase up to the occurrence of creep fracture,which is thought to be the fracture mechanism of the alloy during creep.

Microstructure and evolution of(TiB_2+Al_2O_3)/NiAl composites prepared by self-propagation high-temperature synthesis

（TiB2＋Al2O3）/NiAl composites were synthesized by self-propagation high-temperature synthesis, and their phase compositions, microstructures and evolution modes were studied. The microstructures and shapes vary with the TiB2＋Al2O3 content in the NiAl matrix. TiB2 particles take a great variety of elementary shapes such as white bars, plates, herringbones, regular cubes and cuboids. These results outline a strategy of self-assembly processes in real time to build diversified microstructures. Some TiB2 grains in sizes of 2-5μm are embeded in Al2O3 clusters, while a small number of TiB2 particles disperse in the NiAl matrix. It is believed that the higher the TiB2＋Al2O3 content is, the more the regular shapes and homogeneous distributions of TiB2 and Al2O3 will be present in the NiAl matrix.

Evolution mechanism of demand for comprehensive transportation system based on metabolic ecology

The metabolic evolution model of transportation demand for comprehensive transportation systems is put forward on the basis of a metabolic theory of ecology. In the model, the growth rates or changing rates of transportation volumes for the various transportation modes of a city are determined not only by the GDP per capita which reflects the size of the city itself, but also by the relationship of competition and cooperation among transportation modes. The results of empirical analysis for Chinese cities show that the allometric growth exponent in the equation for the variation rate of passenger demand volume on rail is greater than the predicted value of 1/4 in metabolic ecology, whereas the allometric growth relationship is not so evident in the equation for the variation rate of passenger demand volume on road. The changing rate of road transportation is thus mainly affected by the relationship of competition and cooperation among transportation modes for Chinese cities.

Microstructure evolution of a new directionally solidified Ni-based superalloy after long-term aging at 950 ℃ upto 1 000 h

The microstructure evolution of a new directionally solidified（DS） Ni-based superalloy used for gas turbine blades after long-term aging at 950 ℃ was investigated.The results show that the γ ＇ phase becomes more regular in dendritic arm and interdendritic area,while both the mass fraction and the size of γ ＇ phase increase gradually with increasing aging time.During long-term aging,the MC carbide dissolves on the edge to provide the carbon for the formation of M23C6 carbide by the precipitation of Cr at the grain boundary.The rose-shaped γ ＇/γ eutectic partly dissolves into γ matrix and the aging promotes it transform into raft-shape γ ＇.The microstructure is generally stable and no needle-like topologically close-packed phase（TCP） can be found after aging for 1 000 h.