简介:Recently,Changetal.proposedaSudoku-basedsecretimagesharingscheme.TheyutilizedtheSudokugridtogeneratemeaningfulshadowimages,andtheirschemesatisfiedallessentialrequirements.BasedonChangetal.'sscheme,weproposeanovel(n,n)secretimagesharingschemebasedonSudoku.Intheproposedscheme,asecretimagecanbesharedamongndifferentcoverimagesbygeneratingnshadowimages,andthesecretimagecanbereconstructedwithoutdistortionusingonlythesenshadowimages.Also,theproposedschemecansolvetheoverflowandunderflowproblems.Theexperimentalresultsshowthatthevisualqualityoftheshadowimagesissatisfactory.Furthermore,theproposedschemeallowsforalargeembeddingcapacity.
简介:Excessivenitrogen(N)fertilizerapplicationtowinterwheatisacommonproblemontheNorthChinaPlain.TodeterminetheoptimumfertilizerNrateforwinterwheatproductionwhileminimizingNlosses,fieldexperimentswereconductedfortwogrowingseasonsateightsites,inHuiminCounty,ShandongProvince,from2001to2003.TheoptimumNrateformaximumgrainyieldwasinverselyrelatedtotheinitialsoilmineralNcontent(Nmin)inthetop90cmofthesoilprofilebeforesowing.TherewasnoyieldresponsetotheappliedNatthethreesiteswithhighinitialsoilmineralNlevels(average212kgNha-1).TheaverageoptimumNratewas96kgNha-1forthefivesiteswithlowinitialsoilNmin(average155kgNha-1)beforesowing.ResidualnitrateNinthetop90cmofthesoilprofileafterharvestincreasedwithincreasingfertilizerNapplicationrate.TheapparentNlossesduringthewheat-growingseasonalsoincreasedwithincreasingNapplicationrate.TheaverageapparentNlosseswiththeoptimumNrateswerelessthan15kgNha-1,whereasthefarmers'conventionalNapplicationrateresultedinlossesofmorethan100kgNha-1.Therefore,optimizingNuseforwinterwheatconsiderablyreducedNlossestotheenvironmentwithoutcompromisingcropyields.