CINXE.COM

Just a moment...

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="120"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "publications.waset.org",cType: 'non-interactive',cRay: '914bef9bdcd5fd2a',cH: 'Dij7J9yVXmS9eW1GSZY6W62JYyNiSHQWaCkh2.bR3zI-1740027657-1.2.1.1-xbbxWR8p7HxK0NZm_0AEUf1wbM5OBZXYsv7iXXaEL8.olZ.0O6PnPN2CQp4jcP7L',cUPMDTk: "\/abstracts\/search?q=levels&__cf_chl_tk=X9TSLriv5dFz2lh8Ug8T.Jx_cOCxMhrUuJbqLucK.Tk-1740027657-1.0.1.1-wfm2W0pAwqfkozZyf4Tt3JEaVkzv3GR7mZL9yTGc7qk",cFPWv: 'g',cITimeS: '1740027657',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported-browser",fa: "\/abstracts\/search?q=levels&__cf_chl_f_tk=X9TSLriv5dFz2lh8Ug8T.Jx_cOCxMhrUuJbqLucK.Tk-1740027657-1.0.1.1-wfm2W0pAwqfkozZyf4Tt3JEaVkzv3GR7mZL9yTGc7qk",md: "6rNSf8s_jinIMnPeLZRWo7N5xeoO4Q_1zn7q7C_DLmI-1740027657-1.2.1.1-w.wFdh_c9NoBTWlGlr7uBvK8YtCrMyE1mwZFu2f35IC9ww.YEP7UrMjTTPHuFrfZpkLAZD0CT7I8Jn74Wb1hT5mOAGa0uz7gXh1q5rCP5P5MfQmD6gAeG7sD8n2VVW6mQTRkfL..7Z9i.sSgwQNrTTe8FPzuqhN0DBfQ95Htkb0GoJWK0p68WJrdmcufBtc_4NZ2PwmeuXUspZuM29kUQKuMZVgWK2TIJyrXFGnzIUdNP_SUFPMK7UEUokFf2mSOO3KEFMkztCMVBhTyC_mIPrZcx.HtfFkWuP6YYkvK7pR4PR5.S3fN3.Lmwcb6_p11Z2u86x2S0vJM2WkITxpP0CMtRLLnXUZpoIVMUTE2YwNVsB2EGT2Gt61.F1P3za5OnuInpAZm6Yscna8GAMvxTTRz9x5pmWBsEnlfIBffV4.ioI9xTMLMRnP.pnxagAXkWBu2LOdJ41clxFLZsqko.2S_ojIK_ysX8A1UoqgIRJJ0tjsr9fnxos2r.Q5K_CG8hJkJzCifhcP1_jtnOAneMTvTm.HeEATsRIsvDlN_eCsHyl3aUI4BwWRIA19PaVjFAYoK63i8s4Uc4Nr2Syr8zggN1XVz8C1YFiBwc6hZ54OoM8f5BpweBUYUAlhQeZcEzGGNOL_hKSa.Ti8gpFTLnuKaMxZ.mujNo3SHZ6tlfUSnuKcBaAhpiNZKafsNTLSesgi0FWQbwNZgCdoCdqSxu5iNDbmvIlikR3hX4UoYV5WhHmBcE1wqbTTIx_5vpviRZAmtdJR5aHnL.73vzXjfW47c6kly.RUxpAO829ABjtaW3YizTjEmDMEEMomz2S1qwMu5RsnnMh8fzkIapsLXMGCynMO.1usqPcQSgo17ctkt_R7yhpfrN4N.uB5romVBqxte_x.HgFhkTg6I_4UHz6TjHpl.U_6M1kH9zlHzNGZrt1ZxZ_AcXW7J_mfVeDKMBXYkOpKF7rcFvy2KmcBDNyQeiOZBWt5XlVaGrE_CdCxJQnMnxNutOUqoihJWdDYyFSfdOY5vSW77qhlFOdMNqrjwPCvPktebh0B4HIWt2Y3N0OtV6cvxoy8fP00TtZdTl5wkxJTgRhVjvLJGHv8DMR3BTzztjFDiBYWnyw7Agn5xFpgCbKOJuhD7WtugEFipMDMD7sJyeqzog5D1JC3_rl9JfKUMvymJ3.vLKFmv0uAiHG_OzMzadkUvDc5lFPL5HElY7EurnCxazu97QPXrESf6yUf1BTdyFk0GUfIjRCJwFvfJ.5rTx0YjGyKPMaVptgS10.J.pYR06giayHE4ngqGr0GE3vxSYgBVYN26EucVNIuaWJZmCAIHFmBYY7ShWtKxKu0.Z4gzHTMGVLNhN9lWfofPGVvjth0i3e53O2wGDcTzPP3nrWOqA6gqBvKBYrjpW6G8fjqCLxQM3OHxaCazrECIeuBa9kRuQOw344b3oini5KlnSNxWVGrVbmjq3Fl8YrRMDrmINuP6KucIoUEySBipujdVXOS.R_2SU5SyuL0rw6QaGu0kLpVDU0F8ggoehsULmCVucZwAydNxfDEBwBimkWkOQneAJu3IWoofah1oPkEkdIm_LWgzgr.6Zz97tdW7EcH0CaBZjSiEszZyoNmqjsRMOB6ucWWlsO4CdLMtl5YXks78OZnFsDOg3UXRf6tzFovr3Cf4YQ9uEJ4f8Zkne5D_9CND23Rb6YQ34_5L7Fy_UwlTP97H8iz29y_fgaXm9vVqYM_bdWCTVNdm94gUNNfV476ZuyWprhm69.zxPT4.kd0oBERo1WzZTQfjVfBx1VIxwIG_nkiLP5zgMlFBvLmYx7EzSWeKK8PiE_8_2h6sjAkHhYYCqDQYZC6Nj.QFTlnTV7xGwL34Mt63k2HtOazYlgEK30XNzeErqQr7yCXkJYz43jrt.OVknmpCRQG_KQhErsEnHqlNQQ",mdrd: "eJPKtESkzFAUIRzEr8dGqDWwvuCT4JCxdyw6MHXIjps-1740027657-1.2.1.1-j5nnpKHxAbgbSX4hgige1JAXRXQBKJfMU9CMlRVOEqPlW2iRH9ij6iSAxc632zUbd3OaJbinjeLS9SnaqxgdF6IOwRi9n88jhFd_AsVjO9guPgVg7qwRYK.CnaKlfPOglJmrnH4s2bpyBb1DOknw.tkJD.1whCl..FQ5qMbXKHXN94ZUdnzvVBNVQwirBODQsWalv_M2z2m7kiu1MtsSkKsscqLYxhqezRD8_rPWb1XOjVRvAQw.ie8Vh29pkgqqfpPDuAinDtbUhDoqjWAkSsImkLLlYt6oUQAKMVQjSIj7BN7ZXM4Ml.lkweSTxAmA5GGizYMts5OLP_SWnjB2TXgV9PJHP2Ti0ta.QK75mUxJ3ubSa1Q3ZYuSowXSApjSyP0KZ2BWOjfj.XkSvOzdh_gMEGakU7lMmMQeHx1x8UhgWqwaCWUlaV7xyVsVF2Z01Tc9YziC1wSF9Fdlja54SP6ykW8fbRKBD.VrcU1EwlLaq0gFMTOMf.mz3a3MZ4fyAX0FUwkcS_gaxC.j2Y8sTLZOxghxhXAyfe4O3LOAJ463_jwei8hfgrWonjr9I2xDq9.kuo4Vxv9lchkKHH9KVqyFPYyipnUJ5SCVrx3orBuC0HFFLe_bvRWJLFe3D46Nts96Mn9EIVeJwRFBOqx9qMHad8XW6eNBAHwZB8Woym428bRhJs3nzHAPYERHa43rnQSDXkOfIxWY.L1q7RGqZLR2USNPNmgO1VNnAfcX5W6EVxbZuT59gxI3Y.2u6xPIC46lch_rdOSPqwEerCCoGNkBe49gBSKkHKvTzusMQkN0YX9f5q5T1jQMlYh7eglAFn1OnXmUxHnBRdzHA4b3B7KjxXz6RQnzNw9LHD1c7rNF3v6bHXRTErcXpDVPiBlgxq49uj1rTQYpHpdQyJaG0q9WedJOEFL1W9OcDwwuAaf414Ak5XhnQpmEqda6yIIqB.Wc54Bx.B18W21Xr_1I9zx2JHB5_ekaKACkQ6PAO.ZxLEM1qouqCqu5bO5rlteoPR8gZxXfQvDUEBhW8RGa9UWwpW2LMteLBQI92XJWQRkPgtjcHoUm3UZKB6c449GgT3UIkxdJ27lZUOPN1qRivgwh2KiKt4iW1QSQJFXYrcyL63fozuflwflE6lTsgpY6M3VNxB9T5wlQGPshwJzQG4CJ.bSd.syEca0Z52HISZHD0k5Ggd5kCXXowxSKgMWfLz5tiD_1AhZFTx1z4P_JrzqXCuxQdk05S.ODWwDLUUnmJYDZBcyF4GHvjr_E3nRvHw_X2ptnh7EZ5rTtYQ48DUxn0qJPT5liFPdAqc6YNB35DCBWLqbfUivHT82sx_wU0g237Yb0C98lSHsZ00Ng0RDhhQZ4oXpfG6BN0.jJxFtnAw.ZRVZxf83c7xASUtbxyg6bXfOXgy06RXdy6TMe5WwCLeXwG2eOMj0e7WUAGfyEK6CkygaOH4Gp2XWs5xdTIBEAgYbJbL38ylPo2Z4o6IKk7lyxOqDopUpTQsIdWJk0jpyU_G4ffB2Q6DC8Ps1Bs8_fgVWHYpUcxFsuUURcM4Fbta3awJmpRDeZsRgLzo8WDxunn6NkLPqAFMbtw0tDheuNzBHLSDQnTamUCHlOt2EzdabYhQWoQ2ASpR3i6amsdVW2hIZo_rlxYX2_m0KEPanPKcigxF3BUH_A4WBRkK8SFkzqE5mU8oaqIQsWZLgtSvN33A4m9KKNPmtI_tnHJ88TmOAyvgPBMaAIvo._U9TJtTiF45m6GqqpL88nh0qORt7dmcVEmmlZeEBqcxRDz8vEErJ5yCwnvTdkUP9xblNn_MRil6c7RoGpyfZrNSEjFS.SgWBrb96vjvFFEtwdcj.4EEN0h2dexUzMJq.O1OcapGYx2ehK2ucd98N5JW2tiXITtBOIx5dLCncIlWK2tI7YMPxInYLe7a5NK6PAysNqTc8tiFSPMvHqOm2sOiguRnbiK88HXiT26FAKx46x"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=914bef9bdcd5fd2a';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/abstracts\/search?q=levels&__cf_chl_rt_tk=X9TSLriv5dFz2lh8Ug8T.Jx_cOCxMhrUuJbqLucK.Tk-1740027657-1.0.1.1-wfm2W0pAwqfkozZyf4Tt3JEaVkzv3GR7mZL9yTGc7qk" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>