三激波滚柱活齿行星传动原理研究

传动原理是研究设计理论的基础,以三激波滚柱活齿行星传动为研究对象,建立了理论齿廓与实际齿廓方程,证明了定传动比,采用不同的安装方式及滚柱数目可得到12种不同的传动比。

波式滚动活齿传动内齿轮齿廓曲线的选择

论述波式滚动活齿传动内齿轮齿廓曲线的两种选择:内摆线的等距曲线、密切圆弧曲线的理论成因。

无溶剂微波辐射下的Knoevenagel缩合反应

采用固体氢氧化钠为催化剂 ,在无溶剂微波辐射下芳香醛与活泼亚甲基化合物发生knoeve nagel缩合反应 ,合成了一系列苄叉基化合物 ,测定了产物的熔点 ,并利用红外光谱、核磁共振及质谱对部分产物的结构进行了表征 ;同时对微波加速反应的机理进行了探讨 .结果表明 ,该方法不但化学选择性好、反应时间短 ( 1.5～ 4min)、产率高 ( 73%～ 95 % ) ,而且产物易处理 ,对环境污染小 .

Thermodynamics and kinetics of carbothermal reduction of zinc ferrite by microwave heating

The kinetics of carbon reduction of ZnFe2O4 in the temperature range of 550-950 °C was investigated in a microwave tank-type reactor. The mechanism of formation of ZnO and Fe3O4/FeO by the decomposition of ZnFe2O4 was detailed using the equilibrium calculations and thermodynamics analysis by HSC chemistry software 6.0. In addition, the effects of decomposition temperature, the C/ZnFe2O4 ratio, the particle size and the microwave power were assessed on the kinetics of decomposition. Zn recovery as high as 97.93%could be achieved at a decomposition temperature of 750 °C with C/ZnFe2O4 ratio of 1：3, particle size of 61-74 μm and microwave power of 1200 W. The kinetics of decomposition was tested with different kinetic models and carbon gasification control mechanism was identified to be the appropriate mechanism. The activation energy for the carbon gasification reaction was estimated to be 38.21 kJ/mol.

摆线凸轮外激波摆杆活齿传动齿形设计

为实现外激波摆杆活齿减速器高传动比、重载的稳定传动,采用三阶导数连续、无刚性柔性冲击的摆线作为外激波凸轮的齿形曲线。建立复直角坐标系,采用复数矢量法设计基激波凸轮齿形,基于转速变换原理和包络理论,推导了中心轮理论及实际齿形方程。分析齿形曲率半径,制定中心轮避免齿形等距干涉的设计条件。分析了传动压力角的变化规律。

Effects of Microwave Blanching Treatment on POD Activity and Crispness in Capsicum frutescens L.

[Objective] To study the effects of microwave blanching treatment on POD activity and crispness in Capsicum frutescens L., and to compare the effects of microwave blanching method, normal blanching method, boiling water blanching and steam blanching. [Methods] In order to obtain the optimal condition for microwave blanching, response surface methodology was used to construct a quadratic regression model describing the effects of microwave power, microwave time and calcium lactate concentration on the POD activity in C. frutescens. [Results] The optimal technology was obtained based on central composite design： 525 W microwave power, 64.5 s microwave time, and 0.08% calcium lactate concentration. Under this condition, POD enzyme activity of C. frutescens was desactivated and crispness of C. frutescens was 68.77 N. [Conclusions] This research would provide references for the crispness protection and enzyme deactivation of C. frutescens.

Herpetin, a New Bioactive Lignan Isolated from Herpetospermum caudigerum

Aim To study the chemical constituents of seeds of Herpetospermum caudigerum. Methods Column chromatography was used in the isolation procedure, and the structure was elucidated by spectral data, whose pharmacologic activity was assayed in vitro. Results A new compound named herpetin was isolated, whose structure was determined to be 3-benzofuran methanol-2, 3-dihydm-2-（4- hydroxy-3-methoxyphenyl ）-4-methoxy-6-[ tetrahydm-2-（ 3-hydroxy-4-methoxyphenyl ）-3-methanol ]-2- furanmethyl, showed significant inhibitory effects on HBV-DNA and the replication and expression of HBsAg and HBeAg. Conclusion Herpetin offers wide research and development prospect.

封面人物 张鑫--2018年平昌冬奥会自由式滑雪女子空中技巧亚军

张鑫,女,1985年8月4日出生于徐州沛县,中国自由式滑雪运动员,在2018年平昌冬奥会自由式滑雪女子空中技巧比赛中勇夺亚军张鑫从小活波好动,儿童时期她从事蹦床运动,13岁时被滑雪教练员发现其运动的天赋.

Effects of Salinity Fluctuation and Dietary Traditional Chinese Herbal Medicines on Survival,Growth and Immunity of Exopalaemon carinicauda

[Objective]The aim of this study was to provide a theoretical basis for the large-scale breeding of Exopalaemon carinicauda. [Method]Effects of salinity fluctuation （S0,S3,S6 and S9 represented salinity fluctuations of 0,3,6 and 9 respectivley） and dietary traditional Chinese herbal medicines （0,1%,2% and 4% respectively） on survival,growth and immunity of E.carinicauda were studied,and its experiment lasted for 60 d. [Result]The results showed that specific growth rate,feed conversion efficiency and superoxide dismutase activity of E.carinicauda in the treatment group with 1% dietary traditional Chinese herbal medicine and S6 salinity fluctuation were higher than those in other treatments,which was significantly higher than the treatment groups with S0,S3 and S9 salinity fluctuation at the same adding level of 1% dietary traditional Chinese herbal medicine. The regression analysis indicated that at S0,S3 and S6 salinity fluctuation,the optimal adding level of dietary traditional Chinese herbal medicines in feeds decreased with the increase of salinity fluctuation,accounting for 2.74%,1.77% and 0.51% respectively. At four adding levels of dietary traditional Chinese herbal medicines,the optimal salinity fluctuation of E.carinicauda also decreased with the increase of dietary traditional Chinese herbal medicines in feeds,accounting for 5.26,4.95,3.54 and 1.97 respectively. [Conclusion]Salinity,dietary traditional Chinese herbal medicines and their interactions have a significant effect on survival,growth and immunity of E.carinicauda,which calls for attentions in the breeding.

Experimental Study on Tissue Ablation with Novel Microwave Probe

Objective: To validate a newly designed microwave probe capable of producing larger volume of ablated lesions in ex vivo swine livers. Methods: A novel microwave probe was developed and tested in ex vivo specimens of swine liver. Group A was not given saline infusion under power output 50 W. Group B, C, D under power output 90 W were tested respectively according to the condition of no saline infusion (group B), 5 min preinfusion (5 ml saline, group C), preinfusion and continuous infusion (at the rate of 1 ml/min, group D) using the novel probe. The sizes of the microwave-induced lesions were evaluated and the volume of the tissue destruction qualified. Results: The approximate volumes of the microwave-induced lesions were (16.48±3.86) cm3, (28.86±6.15) cm3, (34.11±5.86) cm3, (40.50±10.88) cm3, respectively (P<0.01). Preinfusion and continuous infusion (group D) created more spherical lesions than only preinfusion (group C). Conclusion: The newly-developed microwave probe increased the volume of coagulation necrosis, created a more spherical lesion under the power output of 90 W, and might achieve the effective treatment of larger neoplasm with a single application of microwave energy.

Analysis of Pseudomomentum Wave-Activity Density in a Heavy Rainfall Event in East China

Taking into account moisture in virtue of general potential temperature,the author derive a three-dimensional(3D) pseudomomentum wave-activity relation for the moist atmosphere from the primitive equations in Cartesian coordinates using the Momentum-Casimir method.Since the wave-activity relation is constructed in an ageostrophic and non-hydrostatic dynamical framework,it may be applicable to diagnosing the evolution and propagation of mesoscale systems leading to heavy rainfall.The theoretical analysis shows that,besides the local change of wave-activity flux divergence and source or sink,the wave-activity relation includes two additional forcing terms.The first is the zonal gradient of difference between general potential temperature and potential temperature perturbations,and the second is the covariance of the solenoid and gradient of water vapor,denoting the direct influence of moisture on wave-activity density.The wave-activity density was applied to a heavy precipitation event occurring in the Jianghuai region of China.The calculation showed that the wave-activity density was consistent with 6-h accumulated precipitation observations,in terms of both spatial distribution and temporal tendency.This suggested that the disturbance represented by wave-activity density was closely related to the heavy precipitation.Although the wave-activity flux divergence and the covariance of the solenoid and gradient of water vapor made the primary contribution to the local change of wave-activity density,the covariance was more remarkable.The zonal gradient of difference between general potential temperature and potential temperature perturbations made a weaker contribution to the waveactivity density.

Synthesis of Hierarchically Porous CaFe204/Carbon Fiber Hybrids and Microwave Induced Catalytic Activity

Hierarchically porous CaFe204/carbon fiber hybrids with enhanced microwave induced cat- alytic activity for the degradation of methyl violet （MV） from water were synthesized from kapok by a novel two-step process coupling pore-fabricating and nanoparticles assembling. The as-prepared samples exhibited characteristic hollow fiber morphology, CaFe204 nanopar- ticles dispersed uniformly on the surface of hollow carbon fibers （HCF）. The effects of various factors such as CaFe204 loading, microwave power, catalyst doses, initial concen- tration of MV solution and pH value on the microwave induced degradation of MV over CaFe204/HCF were evaluated. It was found that the microwave induced degradation of MV over CaFe204/HCF had high reaction rate and short process time. The kinetic study indicated that the degradation of MV over CaFe204/HCF followed pseudo-first-order kinet- ics model. The high catalytic activity of CaFe204/HCF was facilitated by the synergistic relationship between microwave induced catalytic reaction and adsorption characteristics.

Large-scale circulation features associated with the heat wave over Northeast China in summer 2018

In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP–NCAR reanalysis data.The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China,and the related downward motions were directly responsible for the extreme high-temperature anomalies.The northwestward shift of the western Pacific subtropical high(WPSH)and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China.In addition,an anomalous Pacific–Japan pattern in the lower troposphere led to the northwestward shift of the WPSH,jointly favoring the anomalous geopotential height over Northeast China.Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes,respectively,and converged over Northeast China,leading to the enhancement of the geopotential height anomalies.

2-Steps Preparation Activated Carbon from Solidago Canadensis:Carbonized by Electrial heating and Activated by Microwave Radiation

The activated carbon(AC)was prepared from Solidago Canadensis(SC),an alien invasive plant.The plant was firstly carbonized under nitrogen at 400 ℃ for 90 min in an electrical furnace,and then the carbonized product was activated with KOH through microwave radiation.Effects of KOH/C ratio,microwave power,microwave radiation time on the adsorption capacities and yield of AC were evaluated.It indicated that the optimum conditions were KOH/C ratio 2 g/g,microwave power 700 W,and microwave radiation time 6 min.The carbonation process of SC was analyzed by thermogravimetry(TG).The pore structural parameters and surface functional groups of the AC were characterized by nitrogen adsorption-desorption and Fourier Transformed Infrared Spectroscopy(FTIR),respectively.The activation yield,the surface area,the average pore size,and the average micropore size of AC prepared from optimum conditions were 53.75%,1 888 m2/g,0.567 nm,and 0.488 nm,respectively.The adsorption amounts of AC were 302.4 mg/g for methylene blue and 1 470.27 mg/g for iodine.

The Use of Ultrasonics in the Treatment of Waste Activated Sludge

The present paper reports on extensive investigations using an ultrasomc treatment ot WAS, to study its potential to meet one or all of four objectives： （1） reduce WAS quantities; （2） achieve a better dewaterability; （3） provoke a release of COD from the biosolids, preferably transformed into biodegradable organics and （4） possibly destroy the filamentous micro-organisms responsible for sludge bulking. The experiments are carried out in a batch reactor of volume up to 2.3L. The ultrasonic apparatus consisted of a generator, a converter and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different sludge kinds were tested, at approximate concentration （DS/WAS） between 3.5 and 20g·L^-1. The release of COD from the WAS-phase into the filtrate phase is a function of the specific energy-input SE with yields of about 30% achievable at SE-values of 30000 kJ·kg^-1. A major fraction of the COD is transformed into biodegradable organics （BOD）. The reduction of DS-fraction of the sludge is equivalent to the COD-release rates. Although the dry solids content （DS） is reduced, the dewaterability of the sludge is not improved. This reflects itself in a slightly decreased dryness of the filter cake using vacuum filtration, and in increased values of the capillary suction time （CST）. This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area. More surface water is bound （CST increases） and the filterability decreases due to clogging of the cake. To reach the same dryness as the untreated cake, the required dosage of poly-electrolyte increases proportionally with the level of ultrasound energy supplied. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. Especially the release of COD and its transformation into BOD certainly merit further research.

Comparison of microwave and conventional heating routes for kaolin thermal activation

The effect of activation properties of the precursors of zeolite directly prepared from kaolin influenced by microwave field and conventional heating was investigated.XRD,TG-DSC,FT-IR,SEM,particle size analysis,specific surface area(BET),pore size distribution(BJH)and N2 adsorption-desorption were discussed to determine the optimal activation temperature.It is concluded that the conversion of kaolin to metakaolin in the microwave field is at 500°C holding for 30 min,which is 100°C lower than that in conventional calcination and 90 min shorter,and the phase transition process of kaolin under the effect of microwave field is the same as that of conventional heating method.SEM analysis indicates that the particle size is more uniform and agglomeration appears slightly in the microwave field.The N2 adsorption-desorption isotherm,BET and BJH of kaolin indicate that the pore properties are almost invariable regardless of calcination route during the process of calcining kaolin into metakaolin.It indicates that microwave calcination is superior to conventional calcination in the activation pathway of kaolin.It is attributed to microwave heating relying on objects to absorb microwave energy and convert it into thermal energy,which can simultaneously and uniformly heat the entire substance.

Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.

Comparative kinetic analysis of conventional and ultrasound-assisted leaching of scheelite by sodium carbonate

For further comprehending the mechanism of the intensification of ultrasound for extraction,the difference of leaching kinetics between the ultrasound-assisted and conventional sodium carbonate leaching of scheelite was studied,and the corresponding kinetic equations were established.The results indicate that the obtained apparent activation energy with or without ultrasound is same 72 kJ/mol,and both reactions are controlled by surface chemical reaction.By comparing the leaching kinetics of scheelite by Na2CO3,NaOH and Na3PO4 reactants with or without ultrasound,a general conclusion for scheelite hydrometallurgy is obtained.For the process with the formation of compact product layer,the intensification of the tungsten extraction with ultrasound mainly reflects in the stripping and elimination of product layer,corresponding to the transformation of kinetic controlling step from diffusion controlling step and reduction of apparent activation energy.For the one without compact product layer or with a loose and porous product layer,the intensification mainly embodies in the increase of frequency factor,and the controlling step and apparent activation energy of the reaction always remain constant.

Multi-Resonant-Activation for a System Only Driven by Multi-State Noise

We consider the escape of the particles multi-state noise. It is shown that, the noise can make over fluctuating potential barrier for a system only driven by a the particles escape over the fluctuating potential barrier in some circumstances; but in other circumstances, it can not. If the noise can make the particle escape over the fluctuating potential barrier, the mean first passage time （MFPT） can display the phenomenon of multi-resonant-activation. For this phenomenon, there are two kinds of resonant activation to appear. One is resonant activation for the MFPTs as the function of the flipping rates of the fluctuating potential barrier; the other is that for the MFPTs as the functions of the transition rates of the multi-state noise.