Characteristics of two Al based functionally gradient composites reinforced by primary Si particles and Si/in situ Mg_2Si particles in centrifugal casting

Two kinds of Al based functionally gradient composite tubes reinforced by primary Si particles alone and primary Si/in situ Mg2Si particles jointly were successfully prepared by centrifugal casting,and their structural and mechanical characters were compared.It is found that the composite reinforced with primary Si particles takes a characteristic of particles distribution both in the inner and outer layers.However,composite reinforced with primary Si/Mg2Si particles jointly takes a characteristic of particles distribution only in the inner layer and shows a sudden change of particles distribution across the section of inner and outer layers.The hardness and wear resistance of Al-19Si-5Mg tube in the inner layer are greatly higher than that in the other layers of Al-19Si-5Mg tube and Al-19Si tube.Theoretical analysis reveals that the existence of Mg2Si particles is the key factor to form this sudden change of gradient distribution of two kinds of particles.Because Mg2Si particles with a lower density have a higher centripetal moving velocity than primary Si particles,in a field of centrifugal force,they would collide with primary Si particles and then impel the later to move together forward to the inner layer of the tube.

A Facile Route for Synthesis of LiFePO_4/C Cathode Material with Nano-sized Primary Particles

A facile and practical route was introduced to prepare LiFePO4/C cathode material with nano-sized primary particles and excellent electrochemical performance. LiH2PO4 was synthesized by using H3PO4 and LiOH as raw materials. Then, as-prepared LiH2PO4, reduced iron powder andα-D-glucose were ball-milled, dried and sin-tered to prepare LiFePO4/C. X-ray diffractometry was used to characterize LiH2PO4, ball-milled product and LiFePO4/C. Differential scanning calorimeter-thermo gravimetric analysis was applied to investigate possible reac-tions in sintering and find suitable temperature for LiFePO4 formation. Scanning electron microscopy was em-ployed for the morphology of LiFePO4/C. As-prepared LiH2PO4 is characterized to be in P21cn（33） space group, which reacts with reduced iron powder to form Li3PO4, Fe3（PO4）2 and H2 in ball-milling and sintering. The appro-priate temperature for LiFePO4/C synthesis is 541.3-976.7 ℃. LiFePO4/C prepared at 700 ℃ presents nano-sized primary particles forming aggregates. Charge-discharge examination indicates that as-prepared LiFePO4/C displays appreciable discharge capacities of 145 and 131 mA·h·g^-1 at 0.1 and 1 C respectively and excellent discharge ca-pacity retention.

Al_(80)Ni_6Y_8Co_4Cu_2 GLASS ALLOYS CONTAINING NANOSCALEPARTICLES BY ISOTHERMAL ANNEALING OR QUENCHING

Al80Ni6 Y8 Co4 Cu2 amorphous ribbons were isothermally annealed and a mixed structure consisting of α-Al particle with a size of less than 15nm and Al3Ni compound with a size of about 30nm was obtained. The crystallization kinetics of Al80Ni6 Y8 Co4 Cu2 amorphous alloy shows that the precipitation of α-Al particles is the growth process controlled by diffusion of the solute elements rejected from the growing crystals. By quenching at different cooling rates, a mixed structure consisting of nanoscale α-Al particles and the remaining glass matrix or structure consisting of nanoscale particle (Al phase or Al3Ni compound) with a size of about 100nm was formed. The addition of Co elements and Cu elements to Al-Ni-Y alloy systems increases the glass formation ability of the alloy and the thermal stability of the supercooled liquid region against crystallization, which results from significant difference of atomic size, strong bonding nature among constituent elements and the low diffisivity of the solute elements due to the concentration gradient in the growing front of crystals.

Particle size distribution and removal by a chemical-biological flocculation process

The particle characterization from the influent and effluent of a chemical-biological flocculation （CBF） process was studied with a laser diffraction device. Water samples from a chemically enhanced primary treatment （CEPT） process and a primary sediment tank process were also analyzed for comparison. The results showed that CBF process was not only effective for both the big size particles and small size particles removal, but also the best particle removal process in the three processes. The results also indicated that CBF process was superior to CEPT process in the heavy metals removal. The high and non-selective removal for heavy metals might be closely related to its strong ability to eliminate small particles. Samples from different locations in CBF reactors showed that small particles were easier to aggregate into big ones and those disrupted flocs could properly flocculate again along CBF reactor because of the biological flocculation.

A New Version of Unified Field Theory—Stochastic Quantum Space Theory on Particle Physics and Cosmology

Stochastic Quantum Space (SQS) theory is a new version of unified field theory based on three fundamental postulations: Gaussian Probability Postulation, Prime Numbers Postulation, Vacuon Postulation. It build a framework with theoretical results agree with many experimental data well. For more information, please refer to the PDF.

Effects of Mg content on primary Mg_2Si phase in hypereutectic Al-Si alloys

Hypereutectic Al-Si alloy with variant Mg contents were fabricated by casting,and the effects of Mg content on the microstructure of primary Mg2Si particles in hypereutectic Al-Si alloys were investigated.The results show that the volume fraction of primary Mg2Si particles increases linearly with raising the Mg content,but the average size of Mg2Si particles does not exhibit a corresponding change.When the Mg content is 3%,á1 0 0？ directions have the fastest growth velocity,so that Mg2Si particles are likely to form octahedron shape.When gradually increasing the Mg content,the distributions of Mg and Si atoms on the solid-liquid interface become inhomogeneous,which results in the formation of irregular octahedron structures.Finally,when the Mg content is about 10%,the morphology of primary Mg2Si particles changes from the octahedron shape into various complex structures with a large size.

Influence of pore structure on thermal stress distribution inside coal particles during primary fragmentation

Thermal stress is an important reason of coal particle primary fragmentation,during which the role of pore structure is ambiguous.Thermal stress induced fragmentation experiments were conducted with low volatile coal/char particles,and the results show that the fragmentation severity enhances with increasing porosity.Various porous thermal stress models were developed with finite element method,and the influences of the pore shape,size,position and porosity on the thermal stress were discussed.The maximum thermal stress inside particle increases with pore curvature,the pore position affects the thermal stress more significantly at the particle center and surface.The expectation of the maximum tensile thermal stress linearly increases with porosity,making the particles with higher porosity easier to fragment,contrary to the conclusion deduced from the devolatilization theory.The obtained results are valuable for the analysis of different thermal processes concerning the thermal stresses of the solid feedstocks.

不同化学制备工艺对α-Al_2O_3粉体形貌和团聚状态的影响

本文描述了以氯化铝为出发原料,有机酸铝盐为前驱体,热分解前驱体制备 Al_2O_3粉体的化学液相制备方法.通过改变制备前驱体工艺方法得到了四种较纯的α-Al_2O_3粉体.利用扫描电镜、透射电镜、比表面测试仪、颗粒沉降仪对四种粉体进行了全面观察与测试.结果表明,该粉体1次粒子的尺寸及形状主要取决于沉淀的最初产生过程.干燥方式对团聚粒子的形态有较大的影响,喷雾干燥有利于形成球形的团聚颗粒.冷冻干燥得到的是高比表面积、多孔结构的团聚颗粒.

Individual and synergistic effect of gamma alumina（γ-Al2O3） and strontium on microstructure and mechanical properties of Al-20Si alloy

An optimized combination of gamma alumina (4 wt.%) and strontium (0.1 wt.%) was incorporated in cast Al-20Si alloy to obtain fine form of silicon. During casting process, the amount of γ-Al2O3 was varied from 0.5.6 wt.% to refine primary Si and Sr was varied from 0.05.0.1 wt.% to modify eutectic Si. The results showed that the average size of primary Si is 24 μm for addition of 4 wt.%γ-Al2O3 to the alloy whereas 0.1 wt.% Sr resulted in sphericity of eutectic Si to ~0.6 and average length of ~1.2 μm. The thermal analysis revealed that γ-Al2O3 can act as potential heterogeneous nucleation sites. Moreover, simultaneous addition of γ-Al2O3 and Sr does not poison γ-Al2O3 particles and inhibit their nucleation efficiency as in the case of combined addition of phosphorous and strontium to Al-20Si alloy. Therefore, it was concluded that enhanced tensile strength, i.e., ultimate tensile strength (increase by 20%) and elongation (increase by 23%) in Al-20Si.4γ-Al2O3.0.1wt.%Sr alloy as compared to as-cast Al.20Si alloy can be attributed to refinement of primary Si, modification of eutectic Si and the presence of α(Al) in the alloy as evident from eutectic shift.

微晶活性α-Al_2O_3微粉在耐火浇注料中的应用

介绍了新研制的微晶活性α-Al2O3微粉,并重点对产品的原晶粒度、吸水率以及其应用性能进行了研 究,结果显示具有极好的应用前景。

In situ prepared Al-Si alloy matrix composites reinforced by γ-Al_2O_3p

A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al（SO4）2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly distributed in the matrix. The results of dry sliding wear tests show that the wear resistance of the composites increases with increasing mass fraction, and the volume loss is considerably lesser than that of the matrix and is lesser than that of the composites by adding γ-Al2O3 particles directly.

γ-Al_2O_3颗粒和铝屑粉末对半固态A356合金初生α相形貌的影响

对比研究了亚微米γ-Al_2O_3颗粒和铝屑粉末对半固态A356合金初生α相的细化行为。结果表明:γ-Al_2O_3颗粒含量增大时,α相晶粒尺寸呈先减小后增大的趋势,形状因子则呈先增大再减小的趋势。铝屑粉末含量增加时,晶粒尺寸呈减小趋势,减小幅度逐渐趋缓;形状因子则呈增大趋势,增大幅度也逐渐趋缓。

预留核心土法爆破开挖下隧道初期支护动力响应特性

初期支护是隧道施工阶段的主要承力结构,爆破施工动力扰动下初期支护的响应规律及安全控制对确保隧道安全快速施工有着重要意义。为研究预留核心土法爆破开挖影响下软岩隧道初期支护的动力响应特征及其安全控制,以林场隧道爆破施工为工程背景,依据隧道初期支护现场爆破振动监测结果,利用ANSYS/LSDYNA建立三维有限元数值计算模型,结合预留核心土法爆破作业特点,研究了两个不同距离爆源同时作用下隧道初期支护的应力分布特征,利用萨道夫斯基经验公式获得了预留核心土法爆破振动传播衰减规律,提出了以应力为控制标准的两侧下台阶同时起爆条件下隧道初期支护的爆破振动速度安全判据。结果表明:不同于全断面法和台阶法爆破,预留核心土法两侧下台阶同时起爆时,最大振动速度出现于隧道初期支护拱脚处,而非隧道底板或拱顶;仰拱未回填区域的存在显著影响爆破应力波传播路径,相较于右侧拱脚,隧道初期支护左侧拱脚处的振动速度更大,且随距离增加而衰减的更明显;初期支护结构稳定性受拉应力控制,最大拉应力及剪应力出现于隧道左侧拱脚处,最大拉应力为7.544 MPa,最大的剪应力为2.78 MPa,均超过规范允许值;根据建立的应力-振速线性关系,提出基于极限强度的隧道初期支护爆破振动安全判据;在林场隧道爆破条件下初期支护的爆破振速安全阈值为10 cm/s。研究成果为隧道爆破施工设计以及安全控制提供理论研究基础。

Application of an extreme learning machine network with particle swarm optimization in syndrome classification of primary liver cancer

Objective: By optimizing the extreme learning machine network with particle swarm optimization, we established a syndrome classification and prediction model for primary liver cancer(PLC), classified and predicted the syndrome diagnosis of medical record data for PLC and compared and analyzed the prediction results with different algorithms and the clinical diagnosis results. This paper provides modern technical support for clinical diagnosis and treatment, and improves the objectivity, accuracy and rigor of the classification of traditional Chinese medicine(TCM) syndromes.Methods: From three top-level TCM hospitals in Nanchang, 10,602 electronic medical records from patients with PLC were collected, dating from January 2009 to May 2020. We removed the electronic medical records of 542 cases of syndromes and adopted the cross-validation method in the remaining10,060 electronic medical records, which were randomly divided into a training set and a test set.Based on fuzzy mathematics theory, we quantified the syndrome-related factors of TCM symptoms and signs, and information from the TCM four diagnostic methods. Next, using an extreme learning machine network with particle swarm optimization, we constructed a neural network syndrome classification and prediction model that used "TCM symptoms + signs + tongue diagnosis information + pulse diagnosis information" as input, and PLC syndrome as output. This approach was used to mine the nonlinear relationship between clinical data in electronic medical records and different syndrome types. The accuracy rate of classification was used to compare this model to other machine learning classification models.Results: The classification accuracy rate of the model developed here was 86.26%. The classification accuracy rates of models using support vector machine and Bayesian networks were 82.79% and 85.84%,respectively. The classification accuracy rates of the models for all syndromes in this paper were between82.15% and 93.82%.Conclusion: Compared with the case of data processed using traditional binary inputs, the experiment shows that the medical record data processed by fuzzy mathematics was more accurate, and closer to clinical findings. In addition, the model developed here was more refined, more accurate, and quicker than other classification models. This model provides reliable diagnosis for clinical treatment of PLC and a method to study of the rules of syndrome differentiation and treatment in TCM.

Emission inventories of primary particles and pollutant gases for China

Detailed high-resolution emission inventories of primary particles(PM2.5,BC and OC) and pollutant gases(SO2,NOx,NH3,CO and VOCs) for China in 2007 were constructed on the basis of the latest fuel consumption data,mostly at the county level,and from socio-economic statistics and data on fossil and biomass fuels obtained from government agencies.New emission factors reflecting local features were also used.The calculated emissions were 13.212 Mt PM2.5,1.4 Mt BC,2.946 Mt OC,31.584 Mt SO2,23.248 Mt NOx,16.017 Mt NH3,164.856 Mt CO and 35.464 Mt VOCs.The national and regional emissions were gridded with 0.5°× 0.5° resolution for use in air quality models.Larger emissions were found in eastern and central China than in western China.The emissions estimated here are roughly equal to those obtained in previous studies,but with different contributions from because of seasonal changes in residential heating and biomass combustion.Finally,uncertainties in inventories were analyzed.

基于VMD的电力系统一次调频混合储能系统容量优化研究

将功率型储能和能量型储能组成混合储能系统,可大幅提升储能系统的对外出力。为充分利用混合储能参与风电场一次调频的优势并考虑经济性因素,提出一种基于变分模态的混合储能容量优化配置方法。首先,以最大化混合储能系统净效益为目标,建立数学模型;接下来,使用变分模态分解将目标信号分解为高频功率需求和低频功率需求;最后,以东北某100 MW风电场为研究实例,取一个典型日的目标功率数据为基础,考虑储能充放电功率和荷电状态等约束条件,使用量子粒子群算法对目标模型进行求解。结果表明,经过优化的储能配置方案可以有效提高混合储能辅助风电场一次调频的经济性。

A More Accurate Determination of the Magnitude of Cosmic Inflation in the Big Bang Model

According to our hypothesis, at the very beginning of the Big Bang, a hyperenergetic spherical wave was created. We described its characteristics in our previous work, and the present work is based on them. Logically, we saw that in cosmic inflation the frequency of such a wave would decrease sharply. Based on the temperature that prevailed immediately after inflation according to the hot Big Bang model, we determined a measure of the size of the inflation in this model, in accordance with our hypothesis.

经导管肝动脉栓塞术联合I 125粒子导管植入治疗原发性肝癌合并门静脉癌栓的疗效分析

目的探讨经导管肝动脉栓塞术联合I125粒子导管植入治疗原发性肝癌合并门静脉癌栓的疗效分析及安全性。方法回顾性分析2022年1月—2023年1月在上海市某医院就诊的30例原发性肝癌合并门脉癌栓患者的临床资料,30例均行TAE联合I125粒子导管植入治疗。每例患者植入粒子数量20~60粒,平均(32.67±12.66)粒,粒子活度为0.8 mCi/粒,长度约为5 mm、直径约0.8 mm,射线有效半径为17 mm,半衰期为59.6 d。植入粒子条1条16例,植入粒子条2条14例。评价指标包括手术成功率、术后并发症、癌栓术前术后对比,甲胎蛋白及肝功能指标术前术后对比,患者总生存期及治疗有效率、累计生存率。结果30例患者手术均获成功,术后10例患者感疼痛,5例患者出现发热,3例患者出现恶心呕吐,对症处理均缓解。癌栓长径术前平均(61.05±12.64)mm,术后平均(42.09±10.92)mm,癌栓明显缩小,差异有统计学意义(P<0.05)。患者术前及术后肝功能指标差异无统计学意义(P>0.05)。30例患者术后3个月、6个月和1年的累计生存率分别86.67%(26/30)、63.34%(19/30)和33.34%(11/30)。随访期内有10例患者接受再次TAE治疗(累计24例次),19例患者死亡。其中最长生存15个月,目前11例患者仍生存,平均中位生存时间为(8.37±3.59)个月。结论TAE联合I125粒子导管植入治疗原发性肝癌合并门脉癌栓安全可行,能有效延长患者生存期。

Numerical investigation of gas-particle flow in the primary air pipe of a low NO_x swirl burner-The DEM-CFD method

The gas-particle flow in the primary air pipe （PAP） of a low NOx swirl burner was investigated using the computational fluid dynamics （CFD） coupled with the discrete element method （DEM）. The mathematical models were validated using the measured values obtained at the outlet of the primary pipe through a phase Doppler anemometer （PDA） system. Particles of different Stokes numbers in the primary air pipe （PAP） were investigated, and the effects of the structure of the primary air pipe and the particle-particle interaction on particle dispersion were analyzed. The results indicate that particles under the combined effects of the Venturi pipe and the spindle body are concentrated into a narrow band area and that the PAP structure can more efficiently concentrate particles with large Stokes numbers. The formed fuel rich/lean jet persists for a long distance out of the burner, thereby favoring of air-staged combustion and NOx reduction. The particle collision frequency and its fluctuation range increase as the particle Stokes number increases. The collisions among particles result in an increase of the spanwise dispersion of particles. Experimental results indicate that the models that take particle-particle collision into consideration are more able to predict particle concentration.

微悬浮聚合工序影响聚氯乙烯糊树脂糊黏度的因素

对微悬浮聚合过程中影响聚氯乙烯糊树脂糊黏度的因素进行了分析,通过一系列生产试验,探讨了影响因素与聚氯乙烯糊树脂糊黏度的变化关系。