Analysis of thickness-shear and thickness-twist modes of AT-cut quartz acoustic wave resonator and filter

The thickness-shear （TS） and thickness-twist （TT） vibrations of partially electroded AT-cut quartz plates for acoustic wave resonator and filter applications are theoretically studied. The plates have structural variations in one of the two in-plane directions of the plates only. The scalar differential equations derived by Tiersten and Smythe for electroded and unelectroded AT-cut quartz plates are used, resulting in free vibration resonant frequencies and mode shapes for both fundamental and overtone fam- ilies of modes. The trapped modes with vibrations, mainly confined in the electroded areas, are found to exist in both the resonator and the filter structures. The numerical results for the trapped modes are presented for different aspect ratios of electrodes and material properties, providing a reference to the design and optimization of quartz acous- tic wave resonators and filters.

Soliton formation in electron-temperature-gradient-driven magnetoplasma

Electron-temperature-gradient（ETG）-driven solitons are studied in a plasma.We derive the linear dispersion relation and an admitted solitary wave solution Korteweg–de Vries-typeequation（Kd V）for the ETG mode in the nonlinear regime by using the Braginskii model and a transformation.It is found that the ETG mode supports only rarefactive solitons.It is also observed that the ratio of electron-to-ion temperature t=T T,e ithe ratio of gradient scale lengths h=L L,（en） Tand the magnetic field B affect both the amplitude and width of a soliton.It is found that the soliton profile changes with variation in these parameters.We apply the homotopy perturbation method to the derived Kd V equation.It is found this method is computationally attractive and the results are very impressive.This work may be useful to study the low electrostatic modes in inhomogeneous electron–ion plasma with density and ETGgradients.For illustration,the model has been applied to tokamak plasma.

Mechanism of water savings and pollution reduction in paddy fields of three typical areas in southern China

Field irrigation and drainage regulation and fertilization application could affect water utilization and pollution transportation in a paddy field.In this study,representative rice-producing areas of Zhejiang Province in southern China were selected to study the effects of different field water level control(conventional irrigation and drainage W0,controlled irrigation and drainage W1 and W2)and different fertilization methods(2 times of fertilization F2 and three times of fertilization F3)on water irrigation quantity and consumption of rice,rice growth,water utilization,and pollution reduction.Results showed that field water level control had a great effect on irrigation quota in growing period rather than that in soaking period,and irrigation quota for W0 was 37.0%-71.7%higher than that for W1 and W2 in the whole growth period of rice.Although the upper limit of rain storage was greatly increased by W1 and W2,on the contrary,the yield under W1 and W2 was 0.4%-2.1%higher than that under W0.Water consumption,water leakage,and evapotranspiration were 16.63%-34.4%,39.97%-60.8%,and 9.40%-31.53%lower under W1 and W2 than those under W0,respectively,while it showed no significant changes under W1 and W2.Rainfall use rate and WUEI(water use efficiency of irrigation)under W1 and W2 had been significantly improved by 8.20%-129.58%and 31.58%-201.61%compared to W0.The contribution of nitrogen and phosphorus loss from surface water accounted for 90%and the total pollution load of total nitrogen(TN),NO_(3)^(-)-N,NH_(4)^(+)-N and chemical oxygen demand(COD)were 20.0%-63.4%,21.8%-66.3%,21.5%-63.8%,and 21.4%-46.5%lower for W1 and W2 than that for W0,respectively.Meanwhile,compared to F2,dispersed fertilization(F3)was beneficial to increase the yield and decrease pollutant load.Additionally,the path of IRA→NH_(4)^(+)-N→COD and IRA→WCA→WUE_(I) presented partial remediation effect,and the effect size was 23.6%and 38.1%,respectively,the path of IRA→WUE_(I)→WUE_(ET) presented a full remediation effect,and the path of IRA→WCA→WUE_(ET) presented suppression effect.