The effects of process conditions on the plasma characteristic in radio-frequency capacitively coupled SiH_4/NH_3/N_2 plasmas: Two-dimensional simulations

A two-dimensional （2D） fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma （CCP） reactor. The plasma–wall interaction （including the deposition） is modeled by using surface reaction coefficients. In the present paper we try to identify, by numerical simulations, the effect of variations of the process parameters on the plasma properties. It is found from our simulations that by increasing the gas pressure and the discharge gap, the electron density profile shape changes continuously from an edge-high to a center-high, thus the thin films become more uniform. Moreover, as the N2 /NH3 ratio increases from 6/13 to 10/9, the hydrogen content can be significantly decreased, without decreasing the electron density significantly.

Extraction Conditions of Essential Oil from Eucalyptus Leaves by Distillation

[Objectives]To explore the extraction conditions of essential oil from eucalyptus leaves.[Methods]The essential oil of eucalyptus leaves was extracted by steam distillation,and the yields of essential oil from eucalyptus leaves under different extraction times,soaking times and different solid-liquid ratios were analyzed through orthogonal test with three factors and three variables.[Results]The effects of various factors on extraction results were:distillation time>solid-liquid ratio>soaking time.When the extraction time and soaking time were 1.5 and 2 h,and the solid-liquid ratio of eucalyptus leaves to distilled water was 1:10,the yield of essential oil was the highest(0.8%).The yield of essential oil increased with the increase of extraction and soaking time,but when reaching the optimal value,the yield decreased with the extension of time.Increasing the solid-liquid ratio can improve the yield of essential oil,but beyond a certain value the yield increased gradually while the cost performance decreased.[Conclusions]The results will provide some reference for the recovery and utilization of eucalyptus leaves.

Effects of Processing Conditions on Hydrothermal Synthesis of K_(0.5)Bi_(0.5)TiO_3 Nano-Powders

Potassium bismuth titanate nanosized powders were prepared by the hydrothermal method using Ti(C_4H_9O)_4 and Bi(NO_3)_3·5H_2O as raw materials in alkaline solution.The phase composition,particle size and morphology of the powders were studied by XRD and TEM analysis.The results showed that the powders were well crystallized and dispersed.The crystal phase of the powders was K_(0.5)Bi_(0.5)TiO_3 with the grain size of about 50 nm～100 nm.Hydrothermal temperature and alkaline concentrations had great effects on the phase composition and morphology of the resultant powders.Pure K_(0.5)Bi_(0.5)TiO_3 powders could be synthesized at 170℃～180℃with KOH concentration of 8 mol/L～12 mol/L.

Magneto-Caloric Effect of Gd5Si2Ge2Compounds under Different Processing Conditions

The magneto-caloric effect of Gd5 Si2Ge2 compounds produced by various techniques is investigated in terms of their magnetization behaviors in the magnetic field from 0 to 2.0 T.The studied materials include arc-melted, annealed and sintered alloys.The results demonstrate that the Gd5Si2Ge2 alloys obtained under different processing conditions possess distinct magneto-caloric effect due to their various microstructures.Proper annealing treatment can enhance the magneto-caloric effect of the alloy remarkably.While the sintered alloy bears relatively lower value of magnetic entropy change ( △ SM) than arc-melted one.The magnetic entropy change of the annealed Gd5 Si2Ge2 alloy arrives the arrives the maximum value of - △SM = 15.29 J· kg-1· K-1 for magnetic field change under 2.0 T in the present work.

Effect of Processing Conditions on the Interlaced Yarn

A new interlacer is used in this paper to investigate the effect of processing conditions on the properties of interlaced yarn. The experimental results show that number of tangles of interlaced yarn changes little with air pressure from 0.2 MPa to 0.5 MPa, and the number of tangles has a maximum value with yarn speed changing. For two yarn directions of entering and leaving yarn guide of interalcer, the yarn speed for the maximum number of tangles is 400 m/rain and 600 m/rain, respectively. The number of tangles changes with air pressure and yarn speed for two yarn directions is compared.

THE EXERGETIC EFFICIENCY OF MSF PROCESS AND THE CONDITIONS OF DESALINATION BY WASTE HEAT

The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found mainly in irreversible heat-transfer and flash evaporationprocesses.However,the basic variables are the temperature drop from stage to stage and the temperaturedifferences between flashed vapor and cooling water.In this paper,the flash temperature difference func-tion,the heat transfer temperature difference function and the total temperature difference function are sug-gested.The proposed temperature difference functions of MSF plant provide a convenient tool to analyse theirreversible behavior and evaluate the exergetic efficiency of this system,because without such improvement thecalculation of the exergetic efficiency of a MSF plant according to the classical formula will be not onlyinconvenient but also insignificant.As a result of present analysis,the reasonable parameters based on theenergy consumption are easily chosen.The above-mentioned principles are confirmed by commercial plants and a pilot plant in Tianjin.

THE APPLICATION OF MICROELECTRODE TO THE STUDY OF MULTISTEP ELECTRODE PROCESSES UNDER STEADY STATE CONDITIONS PART I EE MECHANISM

Under steady-state conditions, the general currents of EE reactions at disk,hemispherical and spherical microelectrodes are derived.From these equations, some electrode reaction parameters can be very simply obtained.

Effect of Deformation Condition on Axial Compressive Precision Forming Process of Tube with Curling Die

The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mainly on geometric condition rp/d0, little on tube material properties and friction condition; the relative gap △/2rp of double-walled tubes obtained decreases with Increasing rp/d0, and there is a parameter k for a given to/do or rp/t0, when rp/d0 >k, △/2rp< 1, otherwise △/2rp>1.

Effect of gelcasting conditions on quality of porous Al-Cu alloy

The porous A1-Cu alloy was prepared by the gelcasting process. And the effects of gelcasting conditions, such as monomer, the volume ratio of cross-linker and monomer, dispersant and redox initiating system on the height, gelling time and the quality of green body were investigated. （It was found that the dispersant and monomer played significant roles in the height and quality of green bodies, respectively.） The optimal conditions were 10% monomer, 2% cross-linker, 0.2% initiator （volume fraction）, and 1.2 g dispersant, in which the green body exhibited the best quality. The mechanisms of process conditions in eliminating the cracks and forming the pores of in the five stages were proposed. Mercury porosimetry provided a description of pore diameter ranging from 10 to 10000 nm and open porosity of 38.78 %.

生物炭基产品及其对土壤培肥改良效应的研究进展

生物炭疏松多孔,具有很强的吸附和抗分解能力,其在农业中的应用不仅实现了秸秆资源的有效利用,还对改良土壤、减少化肥使用、增强土壤固碳能力和降低温室气体排放具有重要意义。然而,生物炭直接用作肥料时,由于其养分含量相对较低,运输和储存成本较高,加之易引起粉尘污染等问题,限制了其在农业中的广泛应用。近年来,将生物炭作为载体或特定功能组分,开发新型土壤培肥改良产品及配套技术,成为推动可持续农业发展的重要方向。通过养分合理组配和控制释放,生物炭基产品不仅能改善土壤结构、提高养分利用率,还能缓解土壤障碍、改善作物生长条件,已成为当前本领域研究热点。本文综述了生物炭基产品的类型、制备工艺、性能评价和在土壤改良与培肥中的应用,指出其对提升土壤质量、促进作物增产和环境保护具有显著效果,未来需加强新材料和技术研发,完善检测标准,加快示范推广,并关注其长期应用的生态环境效应。

Optimization of Extraction Process for Polysaccharides of Urtica fissa E. Pritz.

[Objectives] To study the optimal extraction process for polysaccharides of Urtica fissa E. Pritz. [Methods] Leaves of wild U. fissa E. Pritz. collected in Nyingchi of Tibet were used as raw materials. Water extraction method was used to extract polysaccharides from U. fissa E. Pritz. Besides,comparison was made for the effects of extraction time,extraction temperature and solid-to-liquid ratio on the yield rate of polysaccharides from U. fissa E. Pritz. In addition,using the extraction time,extraction temperature and solid-to-liquid ratio as factors,L9( 33) orthogonal experiment was carried out to determine the optimal process parameters for water extraction of polysaccharides from U. fissa E. Pritz.[Results] The optimal process parameters: hot water extraction time was 4 h,the extraction temperature was 90℃,and the mass ratio of water to leaves of U. fissa E. Pritz. was 1∶ 25. Under such extraction conditions,the yield rate of polysaccharides from U. fissa E. Pritz.was up to 11. 611%. [Conclusions]This experiment is expected to provide certain reference for reasonable development and utilization of wild U. fissa E. Pritz. resources in Tibet.

河道疏浚底泥脱水技术及工艺优化研究进展

底泥脱水是底泥实现后续处置的最重要一环。归纳总结了目前底泥脱水技术研究现状,对常用的底泥脱水技术、底泥脱水调理剂进行了调研,并对底泥脱水设备的工艺优化进行了总结,发现目前单一的底泥脱水技术均有一定的缺陷。建议在对单一技术进行优化的同时,开发其他辅助高效低耗的新型底泥脱水技术。以期为底泥脱水技术在我国的发展和研究工作提供有效借鉴。

基于模糊层次分析法的淤泥板框压滤脱水调理剂综合性能评价

淤泥调理剂是提升淤泥机械脱水固化处置效率的关键因素,目前缺乏淤泥调理剂筛选的综合性评价方法。文章对比研究了聚丙烯酰胺(PAM)、聚二烯丙基二甲基氯化铵(PDDA)、聚合氯化铝(PAC)、粉煤灰、商业固结剂和生石灰6种调理剂在淤泥板框压滤脱水工艺中的使用效果,分析了不同调理剂使用下淤泥脱水尾水的水质差异。充分考虑淤泥脱水效果、淤泥脱水尾水水质和运行维护投入3个方面因素,运用模糊层次分析法对调理剂的作用效果进行综合评价。结果表明,生石灰在淤泥脱水效率的提升方面效果最优,其次为PAC、PDDA和PAM。在淤泥脱水尾水水质方面,PAM、PDDA和PAC会显著降低尾水的浊度、COD、总氮和总磷,生石灰则会导致尾水的pH、COD和总氮升高,造成尾水水质恶化。模糊层次分析法评价结果显示,PDDA为最优的淤泥调理剂。该方法避免了对调理剂效果评价的片面性,为河湖淤泥机械脱水工艺中调理剂的科学筛选提供了依据。

Probabilistic prediction of expected ground condition and construction time and costs in road tunnels

Ground condition and construction （excavation and support） time and costs are the key factors in decision-making during planning and design phases of a tunnel project. An innovative methodology for probabilistic estimation of ground condition and construction time and costs is proposed, which is an integration of the ground prediction approach based on Markov process, and the time and cost variance analysis based on Monte-Carlo （MC） simulation. The former provides the probabilistic description of ground classification along tunnel alignment according to the geological information revealed from geological profile and boreholes. The latter provides the probabilistic description of the expected construction time and costs for each operation according to the survey feedbacks from experts. Then an engineering application to Hamro tunnel is presented to demonstrate how the ground condition and the construction time and costs are estimated in a probabilistic way. In most items, in order to estimate the data needed for this methodology, a number of questionnaires are distributed among the tunneling experts and finally the mean values of the respondents are applied. These facilitate both the owners and the contractors to be aware of the risk that they should carry before construction, and are useful for both tendering and bidding.

Process-condition-driven Automatic Location of Components

In order to reduce the development cycle of mechanical products and corresponding toolings, a large number of components are utilized in these structures. Accordingly, automatic location method for components is a key issue in the research on intelligent computer aided design （CAD） techniques. Integrated with the investigation into intelligent design techniques for aircraft manufacturing toolings, in-depth researches on this issue are conducted. Formalized automatic location principles, representative methods and implementation algorithms are proposed and established. First, several terms and their formalized representative methods including process condition, location base and location operator are defined. Second, computation modeling of components automatic location and methods of location transformation are proposed. Then, definition of base structure and some key algorithms for automatic location are introduced. These principles and algorithms are developed, applied and verified in research project ＂Jig Intelligent CAD （JiglCAD） System＂.

空调翅片成形工艺与模具设计

以厚度0.25 mm的波纹翅片为研究对象,确定了其成形工艺,并设计了级进模,模具可实现1~12列任一列直线切断,通过气动、电控装置实现间歇性横切切断,满足不同片形的生产需要;利用Dynaform对拉深工序进行有限元模拟,模拟的翅片无起皱、破裂等缺陷。经实际试制表明:模具结构合理,翅片成形良好,为类似翅片成形提供参考。

空调外机锌铝镁免喷涂底盘的应用探讨

主要通过对镀锌铝镁钢板制作的室外机底盘的耐腐蚀性和底盘的加工工艺进行研究,为镀锌铝镁钢板在空调外机底盘上的应用提供了依据,以推动镀锌铝镁钢板在空调室外机底盘上的应用和普及。研究结果表明,镀锌铝镁钢板具有相比镀锌钢板更好的耐腐蚀性能和自润滑性,通过铆接后可以不喷涂直接用于空调的室外机底盘。

城市沼渣堆肥工艺及其施肥技术的优化

为探讨缩短城市沼渣堆肥时间,提高堆肥效率和沼渣施肥技术,采用二步法对好氧堆肥工艺进行物料配比中试试验,开展毛豆种植的沼渣施肥试验.研究结果表明:调理剂菇土、稻壳、木屑可以促进堆肥效率;堆体初期24h,它们比对照组的温度分别提高8,5,3℃,产品水的质量分数分别减少45%,38%,14%,种子发芽率指数分别提高10%,8%,7%,产品粒度分别减少54%,34%,20%;毛豆种植配施沼渣有机肥与对照施肥比较,产量增加9.4%,土壤渗漏水硝态氮、总磷质量浓度分别减少13.4%,21.6%,配施沼渣有机肥有利于毛豆增产和降低菜田氮磷淋失.

高效调质低温制粒工艺对颗粒饲料加工质量及维生素E保留率的影响

本试验旨在研究同一饲料配方条件下,高效调质低温制粒工艺对颗粒饲料加工质量及维生素E保留率的影响。对照组(A组)饲料采用普通畜禽饲料加工工艺,试验组饲料分别选用3种调质器,即双层调质器(B组)、调质保持器(C组)及膨胀器(D组),对饲料配方中大料混合料进行湿热处理,经湿热处理后的大料混合料与添加剂和其他饲料原料混合后经低温(50、55、60和65℃)调质后制粒。结果表明,大料混合料经双层调质器处理后淀粉糊化度显著低于调质保持器及膨胀器处理后(P<0.05)。D组淀粉糊化度显著高于B组及C组(P<0.05),C组颗粒硬度显著高于B组及D组(P<0.05),C组颗粒耐久性指数显著高于B组及D组(P<0.05),B组颗粒成型率显著低于其余3组(P<0.05),B组、C组及D组维生素E保留率显著高于A组(P<0.05)。65℃组淀粉糊化度显著高于50、55及60℃组(P<0.05),65℃组颗粒硬度显著高于50、55及60℃组(P<0.05),65℃组颗粒耐久性指数显著高于50、55及60℃组(P<0.05),65℃组颗粒成型率显著高于50及55℃组(P<0.05),65℃组维生素E保留率显著低于50、55及60℃组(P<0.05)。由此可见,大料混合料经调质保持器加工熟化,采用65℃低温制粒能有效保护维生素E热敏性成分,且饲料加工质量与普通畜禽饲料加工工艺制得的饲料无显著差异。

沉积过程的河流相随机建模方法改进及应用

Alluvsim算法通过模拟河道沉积过程达到再现储层形态的目的，但其条件化是一个难题，限制了其实际应用。为了解决源程序密集井条件化困难问题，根据条件数据与河道中线的空间配置关系，创建了条件化的3种改进方法，即局部条件化方法、旋转条件化方法及整体条件化方法。理论模型比较研究表明，该方法在保证河流沉积成因和形态不变的情况下，能够完全忠实于井数据，条件化效果较原始方法要好。利用改进后的方法实现了密井网区储层条件化建模，能够直接服务于河流储层精细三维模型建立。