Numerical Simulation and Experimental Research on Microstructural Evolution During Compact Hot Extrusion of Heavy Caliber Thick-Wall Pipe

Compact hot extrusion(CHE) process of heavy caliber thick-wall pipe is a new material-saving production process. In order to reveal the optimum hot extrusion parameters in CHE process, the e ects of the extrusion parameters on the microstructural evolution are investigated systematically. The metadynamic recrystallization(MDRX) kinetic models and grain size models of as-cast P91 steel are established for the first time according to the hot compression tests performed on the Gleeble-3500 thermal-simulation machine. Then a thermal-mechanical and micro-macro coupled hot extrusion finite element(FE) model is established and further developed in DEFORM software. The results indicated that the grain size of the extruded pipe increases with the increasing of initial temperature and extrusion speed, decreases when extrusion ratio increases. Moreover, the grain size is more sensitive to the initial temperature and the extrusion ratio. The optimum hot extrusion parameters are including that, the initial extrusion temperature of 1250 °C, the extrusion ratio of 9 and the extrusion speed of 50 mm/s. Furthermore, in order to verify the simulation precisions, hot extrusion experiment verification on the heavy caliber thick-wall pipe is carried out on the 500 MN vertical hot extrusion equipment. The load–displacement curve of the extrusion process and the grain sizes of the middle part extruded pipe are in good accuracy with the simulation results, which confirms that the hot extrusion FE models of as-cast P91 steel could estimate the hot extrusion behaviors. The proposed hot extrusion FE model can be used to guide the industrial production research of CHE process.

Two stages power generation test of the hot dry rock exploration and production demonstration project in the Gonghe Basin,northeastern Qinghai-Tibet plateau,China

The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.

Land Suitability Evaluation of Zanthoxylum schinifolium in Dry and Hot Valley of Jinsha River: A Case Study of Jiaopingdu Town of Luquan Yi and Miao Autonomous County,Yunnan Province

According to the recent practice in Laopingzi Village,Jiaopingdu Town,Luquan Yi and Miao Autonomous County(Luquan County hereinafter)in dry and hot valley of Jinsha River,the development of Zanthoxylum schinifolium Sieb.et Zucc planting industry can help farmers gradually get rid of poverty and achieve a virtuous cycle of ecological environment.It is a sustainable poverty alleviation way.Based on the three aspects of soil properties,climatic conditions,and topographical conditions influencing the growth of Z.schinifolium,this paper selected eight evaluation factors to establish a suitability evaluation system for Z.schinifolium,used the analytic hierarchy process to determine the indicator,and determined the weight of the evaluation indicators.Besides,it calculated the comprehensive suitability index of land suitability of Z.schinifolium and evaluated the suitability of Z.schinifolium land in Jiaopingdu Town of Luquan County.The results showed that the suitable area for the cultivation of Z.schinifolium in Jiaopingdu Town reached 7270.78 ha,accounting for 88.69%of the study area;the area of unsuitable land was 922.07 ha,accounting for 11.31%of the study area.Among the suitable land areas,the high suitability area reached562.99 ha,accounting for 7.79%;the moderate suitability area was 2206.76 ha,accounting for 28.61%;the low suitability area was4599.03 ha,accounting for 63.6%.Based on the results of suitability evaluation,it came up with pertinent recommendations for the development of Z.schinifolium industry in Jiaopingdu Town.

Augmenting the Heat Sink for Better Heat Dissipation

Heat sinks were invented to absorb heat from an electronic circuit conduct, and then to dissipate or radiate this heat to the surrounding supposedly, ventilated space, at a rate equal to or faster than that of its buildup. Ventilation was not initially recognized as an essential factor to thermal dispersion. However, as electronic circuit-boards continued to heat up, circuit failure became a problem, forcing the inclusion of miniaturized high speed fans. Later, heat sinks with fins and quiet fans were incorporated in most manufactured circuits. Now heat sinks come in the form of a fan with fans made to function as fins to disperse heat. Heat sinks absorb and radiate excess heat from circuit-boards in order to prolong the circuit’s life span. The higher the thermal conductivity of the material used the more efficient and effective the heat sink is. This paper is an attempt to theoretically design a heat sink with a temperature gradient lower than that of the circuit board’s excess heat.

Application of hot melt extrusion to enhance the dissolution and oral bioavailability of oleanolic acid

The aim of this study was to improve the in vitro dissolution rate and oral bioavailability of oleanolic acid(OA), a water insoluble drug belonging to BCS class IV. Hot melt extrusion(HME) was applied to develop OA amorphous solid dispersions. The characterizations of the optimal formulation were performed by differential scanning calorimetry, X-ray powder diffraction, Fourier transform infrared spectroscopy and in vitro dissolution test.The in vivo pharmacokinetic study was conducted in rats. As a result, OA solid dispersion based on PVP VA 64(OA-PVP) was successfully prepared. In the dissolution medium containing 0.3% SDS, OA-PVP dramatically increased the releasing rate of OA compared with the physical mixture(PM-PVP) and commercial tablet. Furthermore, OA-PVP exhibited higher AUC(P < 0.05) and Cmax(P < 0.05) than PM-PVP and commercial tablet. The superior dissolution property and bioavailability of OA-PVP mainly attributed to the amorphous state of OA in PVP VA64 and the well dispersion caused by thermal melting and shearing. Overall, hot melt extrusion was an efficient strategy to enhance the dissolution rate and oral bioavailability of OA.

HOTO工具箱系列设计,工具也要美美的

来源:https://www.red-dot.org/zh/project/hoto-toolbox-series-63470HOTO工具箱系列产品颜值在线、布局合理、携带方便。它极简优雅的外观设计,打破了人们心中对传统工具笨重、不美观的刻板印象,甚至让人丝毫看不出这是存放电动工具的产品。HOTO工具箱系列的外观以浅色为主,设计简约、线条柔和,边缘圆润。实用的提手和开合扣与整体设计融为一体,方便携带。极具设计美感的外观让它可与任何现代生活环境和谐地融为一体,无需像其他电动工具那样,只能放在储藏室或杂物间里。传统的工具箱一般都配有大量功能复杂的小工具,而HOTO系列则只提供了专为家庭使用而研发的四套工具,不同工具的组合使用可以满足用户的个性化需求。

A new constitutive theory for extrusion-extensional flow of anisotropic liquid crystalline polymer fluid

A new continuum theory of the constitutive equation of co-rotational derivative type was developed by the author for anisotropic viscoelastic fluid-liquid crystalline (LC) polymers (S.F. Han, 2008, 2010) . This paper is a continuation of the recent publication [1] to study extrusion-extensional flow of the fluid. A new concept of simple anisotropic fluid is introduced. On the basis of anisotropic simple fluid, stress behavior is described by velocity gradient tensor F and spin tensor W instead of the velocity gradient tensor D in the classic Leslie?Ericksen continuum theory. A special form of the constitutive equation of the co-rotational type is established for the fluid. Using the special form of the constitutive equation in components a computational analytical theory of the extrusion-extensional flow is developed for the LC polymer liquids - anisotropic viscoelastic fluid. Application of the constitutive theory to the flow is successful in predicting bifurcation of elongational viscosity and contraction of extrudate for LC polymer liquids–anisotropic viscoelastic fluid. The contraction of extrudate of LC polymer liquids may be associated with the stored elastic energy conversion into that necessary for bifurcation of elongational viscosity in extrusion extensional flow of the fluid.

Research on microstructure and high-temperature friction and wear properties of a cobalt-based alloy for hot extrusion die

The hot extrusion die is a key tool for determining the surface quality and dimensional accuracy of extruded products.Because its service process is subject to high temperature,high pressure,and wear,it must be resistant to these conditions.In this paper,the high-temperature friction and wear properties of a cobalt(Co)-based alloy were investigated and compared with those of a titanium carbide(TiC)cemented material.The results show that the high-temperature wear performance of the Co-based alloy is better than that of the TiC cemented material,and that Co-based materials have the potential for replacing TiC cemented materials as hot-extrusion-die materials.Due to the high density and good combination of the matrix and carbide,the carbides do not easily peel off from the matrix during the wear process.Due to the higher impact toughness of the Co-based alloys,microcracks that can cause worn-surface peeling are not easily generated.As a result,the high-temperature wear performance of Co-based alloys is found to be better than that of TiC cemented materials.

基于改进型跟踪微分器的HOT-FSMO无感控制

针对传统一阶磁链滑模观测器存在较大滑模抖振和相位延迟问题,文中提出了一种基于改进型跟踪微分器的高阶终端磁链滑模观测器(High-Order Terminal Flux Sliding Mode Observer,HOT-FSMO)。通过设计一种高阶滑模控制律实现磁链估计的抖振抑制,并结合了一种含终端吸引子的低抖振新型跟踪微分器取代传统低通滤波器以便精确跟踪磁链和转子位置,从而实现滤波功能。实验结果表明,在不同转速和负载条件下,相比于传统线性磁链滑模观测器,基于新型跟踪微分器的高阶终端磁链滑模观测器能够有效降低滑模抖振,减小位置估计误差,并加快系统的响应速度,提高系统的动态性能。

Bulk Al–Al_3Zr composite prepared by mechanical alloying and hot extrusion for high-temperature applications

Bulk Al/Al_3Zr composite was prepared by a combination of mechanical alloying(MA) and hot extrusion processes. Elemental Al and Zr powders were milled for up to 10 h and heat treated at 600℃ for 1 h to form stable Al_3Zr. The prepared Al_3Zr powder was then mixed with the pure Al powder to produce an Al–Al_3Zr composite. The composite powder was finally consolidated by hot extrusion at 550℃. The mechanical properties of consolidated samples were evaluated by hardness and tension tests at room and elevated temperatures. The results show that annealing of the 10-h-milled powder at 600℃ for 1 h led to the formation of a stable Al_3Zr phase. Differential scanning calorimetry(DSC) results confirmed that the formation of Al_3Zr began with the nucleation of a metastable phase, which subsequently transformed to the stable tetragonal Al_3Zr structure. The tension yield strength of the Al-10wt%Al_3Zr composite was determined to be 103 MPa, which is approximately twice that for pure Al(53 MPa). The yield stress of the Al/Al_3Zr composite at 300℃ is just 10% lower than that at room temperature, which demonstrates the strong potential for the prepared composite to be used in high-temperature structural applications.

Two-stage dynamic recrystallization and texture evolution in Al-7Mg alloy during hot torsion

Hot torsion tests were performed on the Al-7Mg alloy at the temperature ranging from 300 to 500℃ and strain rates between 0.05 and 5 s^(-1) to explore the progressive dynamic recrystallization(DRX)and texture behaviors.The DRX behavior of the alloy manifested two distinct stages:Stage 1 at strain of≤2 and Stage 2 at strains of≥2.In Stage 1,there was a slight increase in the DRXed grain fraction(X_(DRX))with predominance of discontinuous DRX(DDRX),followed by a modest change in X_(DRX) until the transition to Stage 2.Stage 2 was marked by an accelerated rate of DRX,culminating in a substantial final X_(DRX) of~0.9.Electron backscattered diffraction(EBSD)analysis on a sample in Stage 2 revealed that continuous DRX(CDRX)predominantly occurred within the(121)[001]grains,whereas the(111)[110]grains underwent a geometric DRX(GDRX)evolution without a noticeable sub-grain structure.Furthermore,a modified Avrami’s DRX kinetics model was utilized to predict the microstructural refinement in the Al-7Mg alloy during the DRX evolution.Although this kinetics model did not accurately capture the DDRX behavior in Stage 1,it effectively simulated the DRX rate in Stage 2.The texture index was employed to assess the evolution of the texture isotropy during hot-torsion test,demonstrating significant improvement(>75%)in texture randomness before the commencement of Stage 2.This initial texture evolution is attributed to the rotation of parent grains and the substructure evolution,rather than to an increase in X_(DRX).

热盐水致大鼠萎缩性胃炎胃粘膜扫描电镜观察

目的:研究热盐水灌胃导致大鼠萎缩性胃炎(CAG)胃粘膜组织细胞超微结构的变化,探讨长期热咸饮食与慢性萎缩性胃炎间的关系。方法:用热盐水灌胃(55℃,150g mL,2 5mL d)建立大鼠萎缩性胃炎动物模型。选取大鼠腺胃胃窦组织进行病理组织学检查,以扫描电镜观察胃粘膜上皮细胞超微结构的变化。结果:光镜下热盐水灌胃后第12周,大鼠胃粘膜出现腺体明显缩小,粘膜肌层的平滑肌呈束状增生插入粘膜固有层中。腺体上1 3至2 3腺上皮萎缩,腺管腔增宽,胃小凹颈部粘膜宽度变窄。扫描电镜见正常组大鼠胃粘膜被纵横交错的小沟分隔成许多胃小区,呈网状,胃小凹(胃腺开口)壁衬有圆形或椭圆形上皮细胞,体积基本一致,有短而稀的微绒毛。上皮细胞排列规则,被覆一薄层连续的粘液。热盐水组大鼠在12周时见胃粘膜细胞表面粗糙,粘膜表面糜烂、扁平;在32周时见胃粘膜细胞萎缩、腺腔直径增大、细胞表面破溃,并见纤维性渗出。结论:热盐水灌胃可引起胃粘膜上皮细胞损害,长期过咸及过热刺激可能会诱发萎缩性胃炎。

Effect of hot isostatic pressure on the microstructure and tensile properties of γ'-strengthened superalloy fabricated through induction-assisted directed energy deposition

The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples subjected to IDED under 1050℃ preheating with and without hot isostatic pressing(HIP,1190℃,105 MPa,and 3 h).Results show that the as-deposited sample mainly consisted of epitaxial columnar crystals and inhomogeneously distributed γ’ phases in interdendritic and dendritic core regions.After HIP,grain morphology changed negligibly,whereas the size of the γ’ phase became increasingly even.After further heat treatment(HT,1070℃,2 h + 845℃,24 h),the γ’ phase in the as-deposited and HIPed samples presented a bimodal size distribution,whereas that in the as-deposited sample showed a size that remained uneven.The comparison of tensile properties revealed that the tensile strength and uniform elongation of the HIP + HTed sample increased by 5% and 46%,respectively,due to the synergistic deformation of bimodal γ’phases,especially large cubic γ’ phases.Finally,the relationship between phase transformations and plastic deformations in the IDEDed sample was discussed on the basis of generalized stability theory in terms of the trade-off between thermodynamics and kinetics.

双相颗粒混合增韧ZrB_2陶瓷复合材料的研究

将增韧相与ZrB2陶瓷基体按配比混料、热压,制备了双相颗粒混合增韧ZrB2陶瓷复合材料,研究了其密度、硬度、力学性能、耐烧蚀性能以及显微组织.结果表明,采用混料热压法能制备99.5%理论密度的ZrB2复合材料;显微硬度为800HV,室温抗压强度为1.397GPa,相对压缩率为21.8%.随着温度升高,强度和压缩率均急剧下降;然而,到1100℃时抗压强度仍高达649MPa,相对压缩率为7.6%.该复合材料在等离子电弧加热器上烧蚀6s后,试样表面温升达2800℃,烧蚀后晶粒长大,部分韧化相熔化飞出,留下孔洞.在氧乙炔焰上烧蚀30s后,试样表面温升达到2000℃,烧蚀后表面无裂纹,表面形成一层氧化膜,晶粒略有长大.

Large-scale physical simulation of injection and production of hot dry rock in Gonghe Basin,Qinghai Province,China

Based on the independently developed true triaxial multi-physical field large-scale physical simulation system of in-situ injection and production,we conducted physical simulation of long-term multi-well injection and production in the hot dry rocks of the Gonghe Basin,Qinghai Province,NW China.Through multi-well connectivity experiments,the spatial distribution characteristics of the natural fracture system in the rock samples and the connectivity between fracture and wellbore were clarified.The injection and production wells were selected to conduct the experiments,namely one injection well and two production wells,one injection well and one production well.The variation of several physical parameters in the production well was analyzed,such as flow rate,temperature,heat recovery rate and fluid recovery.The results show that under the combination of thermal shock and injection pressure,the fracture conductivity was enhanced,and the production temperature showed a downward trend.The larger the flow rate,the faster the decrease.When the local closed area of the fracture was gradually activated,new heat transfer areas were generated,resulting in a lower rate of increase or decrease in the mining temperature.The heat recovery rate was mainly controlled by the extraction flow rate and the temperature difference between injection and production fluid.As the conductivity of the leak-off channel increased,the fluid recovery of the production well rapidly decreased.The influence mechanisms of dominant channels and fluid leak-off on thermal recovery performance are different.The former limits the heat exchange area,while the latter affects the flow rate of the produced fluid.Both of them are important factors affecting the long-term and efficient development of hot dry rock.

挤压膨化过程中物料组分的变化分析

挤压膨化加工广泛应用于食品加工业。挤压膨化过程中,物料组分发生了复杂的物化变化。在高温、高压、高剪切力环境下,淀粉分子间的氢键断裂,淀粉发生糊化、降解,生成小分子量物质,淀粉水溶性增强;蛋白质发生变性、重组,发生组织化,蛋白质水溶性和生物学效价下降;脂肪与淀粉以及蛋白质形成脂肪复合体,淀粉溶解性和消化率降低,脂肪氧化速度减慢,氧化程度减小,产品货架期延长。

热挤压法生产紫铜电脑散热片的研究

分析了电脑散热片产品的截面形状特点和该产品在挤压过程中的模具工况,从模具的强度出发,优化设计了一套分流挤压模具,用高温挤压成形技术进行电脑散热片实心型材成形实验。研究结果表明:通过减小悬臂承受的压力和受力面积以及转化悬臂的受力形式等结构优化设计,可以使悬臂的受力和变形减小,保证和加强了模具的强度,分流挤压模具没有出现任何失效形式,并保证了挤压制品的质量。利用SEM技术对产品焊合部位组织进行分析,产品的分流焊合部位和非分流焊合部位的组织都很致密,焊合质量较好。

Optimisation of Thermal Comfort of Building in a Hot and Dry Tropical Climate: A Comparative Approach between Compressed Earth/Concrete Block Envelopes

Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.

酿酒葡萄延迟栽培方式的研究

利用西昌地区丰富的光热资源,以3年生真芳德和梅尔诺为试材,2000年在西昌正大葡萄试验园进行了酿酒葡萄延迟栽培的研究。摘除一次花序,对新梢分别在花后20、40、60、80d进行中梢修剪,逼迫冬芽萌发结果。结果表明:真芳德具有较强的冬芽副梢结果能力。在延迟栽培条件下,两品种的果实成熟期可推迟到11月上中旬。单株产量、果实可溶性固形物含量和总糖的最大值均出现在花后60d的处理中;各处理滴定酸均高于对照;出汁率随处理时间延迟而降低。两品种花后40、60和80d处理的果实黑痘病和白腐病的发生均低于对照。冬芽副梢成熟度良好。结果表明,延迟栽培能够有效调节葡萄成熟期并改善原料质量,但同时也造成产量的下降和生产周期的加长。

陈化早籼糙米对仔猪小肠黏膜二糖酶及生产性能的影响

本试验研究了在经膨化处理的陈化早籼糙米日粮中添加外源α 淀粉酶和糖化酶对断奶仔猪小肠黏膜二糖酶、血液生化指标和生产性能的影响.试验为日粮不同加工处理(膨化、不膨化)和加外源酶(添加、不添加)两因子设计,共 4 个处理.结果表明,试验猪的生产性能总体趋势是非膨化组好于膨化组,非膨化加酶组的日增重比膨化加酶组在第 14 天和第 28 天分别高出 23 66%和16 83%,料肉质量比降低了16 88%和7 36%;膨化和添加外源酶显著提高了断奶仔猪试验第 14天十二指肠中麦芽糖酶的活性,然而膨化显著降低了断奶仔猪试验第 28 天空肠中乳糖酶、麦芽糖酶、异麦芽糖酶和蔗糖酶的活性,添加外源酶显著提高了断奶仔猪试验第 28 天空肠中乳糖酶和麦芽糖酶的活性.试验结果表明,对断奶仔猪高糊化度膨化陈化糙米是没有必要的.