CINXE.COM

<!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: '917c080c5fd98333',cH: 'I_gPYGN_5y1nH10nrK4rjVCi7Ejb4rIrYoa9abIdsJw-1740531975-1.2.1.1-MvGoBsjP8n58.dUdskFMJ6JwDbc9UGbIViaw.X1qvyBCijTmHSRMJmsfU7vUrt.M',cUPMDTk: "\/abstracts\/search?q=Perpetual%20Onyejelem&__cf_chl_tk=8zVSMHoEeOjw401ht_QoTYAXz7lTJZzcA9NEohXBiY4-1740531975-1.0.1.1-eN1fLFXkZ216lcmNfS5W9IReXbVzJC8Ek429g3p2ipg",cFPWv: 'b',cITimeS: '1740531975',cTTimeMs: '1000',cMTimeMs: '120000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/abstracts\/search?q=Perpetual%20Onyejelem&__cf_chl_f_tk=8zVSMHoEeOjw401ht_QoTYAXz7lTJZzcA9NEohXBiY4-1740531975-1.0.1.1-eN1fLFXkZ216lcmNfS5W9IReXbVzJC8Ek429g3p2ipg",md: "1G.wJ23UotHKxfTgNWUiKtncNrMUfwDc9aCoFD9I..E-1740531975-1.2.1.1-WPcgaR8_BPCw8c.SBtKUx8IhFemftImf5ceXU9XCbwEVkIgXdvEZgxF6RoyY2zdJ4Hhs9Xwuo.BjZGPc5FKP6w5QYbEsC5iBD3MpQWzXo.qiV_AbVJk9AMBrGyxbhczSREervcdq18Yx8DVFLm2ITQB47djwkfp_GXWxyfU6Xv.L55Nkeo7OiP6uLt_.i85M5r_cR7mRoO0AltvIVYkq2tWsyH69CvRKpv2s2JqvqwWlJ8931z2hw3bY_oUKVobls8LYcn_KpklR8xZzB6ToFYsv4YMZtWwqHGs1B07nZBO9jWC91bTDwex1hr8hduPerqWC_xAl.ZX5o5f_szOehRSTVDjRImFPz0R0GVRHje4BhFCnLnjdduAKbIx7RNfnMqYT8Zp5rKmEYgHgYOeNaXJbtt5.5s4VfakypoVSVXxzz0PC4gwFFdwXWpqOPBljXVfPL3nLPs0St1yAqXe.3m1v6u6W1INj_2aZCBcXL0GFxd4A.SwzatzY0vnZo04lcWN7p04t3y_bkH14AwgJc1ji5GT8DsQKXqV2ySkn9KnPnkwY.fF934vqakSMEVXALq2gzQF39MUTcyPf1PR7xbEXoSwxMs5mLtS7cBlPx6NlSsu3e668Qity1wkjx0qqfsrfWUQZS5lfkDiwomfGm7KaLI3SC_KcJMhN955u_kf2dKdueBnjyDRGdrutAkxlwJgLpEYNeEDlsf6iQNVEWs00wHe6UyQSl5zQL5gYTYC8qS3hznY_Ti8YqwQkv6W.MYy7BbpfOSzYOMWi6n8drP_e44WyRMe62wWFuM8sFzdtze0CiNd9RDfkD.r4.__G96x4gws2OPJ5OCfgYLd3zSZgnEuhscfFCdLZIN5eQg1XtWqx1XN8K61w94UF.eGBniy6UxEWVJzR_SuYAR13N8mZIalUHJtnkm_tBsu2gkAw1YdOE_nEWiCpQ8goxK_A3d2T3.jMW1YHFW05GFjT82Y2xtgGXeRr8hkLSlppcbK3WWcoJ1o.Dd4p5vXaLD.KsRnBBLiYOJcT6E97svEXebhYacYZi65odM2pIQB8QQhFXuwTrEfKCNreIrGgXfcsVTX7hB.Qvc.rjrUla9W6Tt.UisSphSYjGZSjCxF9OOBlT4TT3l9GJhp9KYOQpHewREdmzBkgLaReepxNcIplgl3VezQsNsSc5WARGX4MUYXExAP1fJXR1RdyRhHiDG528vCL64ESWgV1HHxctLQVKy_WVkLLprXFxWdiT9IGGEKj63vya.tkghRapJETmjEJEiBZlNhr0d__uTEGdEakK80zd8Pm.ok4a3DaQwcce.NwGq0q11Or0eZ6VnQqHze8by9CQOCoxg6wl5ZdrS06CP4XG6_y7oq0BHgpzglvy7Ul8aLXUmqHCzdxb3xUjbO8wbKIuznHT3T.nEd6Ww.6cfvTY5uL7ZWCnnJtMSA_qtASwkSAHpM6gLDC8KJJnUucRVA6MhCkv3CbQ3IV.loQIk39kgXykiVDn9Q139wH220iC3QADyHPS_5gngTkpT0i3nZDzugSdLfGMbN9YMppB8DN3sRi_nEAzo56ObmC_jJ8FbxuWckHYpmxbOS2ujdS7MxqKse1dUduSXu4yDz0TX1rjRTGqgKnKsgOxzMH040majOzB0kh7HKgHUfDp33i3hCLNmdgqZPkzVLWVk4HQhoI5PkRJLF.VvS98EPEbV_KvFTcq4QDHJkhkbD7DXTTp16PzcKQ4jSIzgblf1p3JAYZbgN1lOiin6No1XJUTlI85jmPxi5aSa9K2ADMTtQ.o1KSNoa6SrVMfWucy3CnZ9QNTdwiYFJCEmnzUCnNoLMFMZQbdJFH7Jr.qmvf.tNMPeH_IuHV3sQXLHCUmzBsVM2a.Q5guq1EZf9CoKrGwR9P2aoEZmvG85j9LDbiO3pdMMr07S6fnwop0jAYJ_F3o9DPJviwu.Ubs0f3A.rHwc2JarHiPtBbG3zBfnhut0ED",mdrd: "noJ1rQXhmSKHmhZe6gNE.mj0i7v8Hh4Y1R9M5Ps5NYY-1740531975-1.2.1.1-2YQRR3EBSlyjsROy35964PCNokl.X8iloNO4cdXuUfHm6Bk1g6jsAcXYfQyVhNYUWH64v2ltLpKCZPhxgwCx_MhK_C5Iylao35u9OhDop_3ggPdJAHH0S5XrWWffjGA_Q8SS2WlFNKWVg5xMYoOqGP9L3YxVHR1aRQlKSMHlPShWPn9IQVM9UWqDoQflpeG0HmyQLY7NMArIIYK4upElGJQ8JnK5UaAmUBN4NU3P.nhCXCb7E9jbpSO9GCQqujMk06.PaLmC3T7NOlyrHVAxCxjCRZ7FYhyYmFHKK8fSQU4ZcNj3l6cCEUgJLN1mms.g1S.Llx7q7Jku3O9kQG.Hh.2wP0W6VzT512U7fXjLAwqUABUK9ZK3.Pzt6NiumTv.g1zj2sP2rtBzT.en1uMLXv4W7YGBs0UqrvPnoVMKsBksptGoIYgLJE93kbpFMGfyJjPT6mEuuplm.bk6B7xDX.NRnrb.OykW2B5O7TibPc6UdV9n_iI9V04VryTQteoYBsJMb.Qdvrg2mDsAmJmBmaocHJxBQx5WAqNW.fQWG1YX8VSYRtgC3VLheiKVSxTexTvwF_FPKYMHYJYtiukZtv5GsOIFhq48D0OtWrMJKNT_.g6JKwO5hnSGOLJVH3B0Wqrb72vNrQAYz7yqdXgoFw8NQmrkKYXzCT6xcdN2vD_MJsPc1RjBqN_D1t8S4j5x6SeGwkY_7LxRrJvhTAYe0V3tpOWe4hqbp8RSqFDcNiOWs9kxZj82GtN9h6N0I3zMNL3MTjzmcbSfZfbLeWrD0OCjzuOmMH..BlTW4hHy2crEosI9oqtilCrdxoHlBFrVRrIa7blpb.tO7qUPIMYpyvlhTsbnDOn8oh3ZgRlo.Yh7Xw4EmOdfhfnbR7OKEByl8KZSKwunZpb58M28gY_MKcrPnZLgvGH0knSTXjA4R5ypk08l2emJ0Ax6J6V6N4_oqyura4KI3Ni_WORSWtVlSH5lOfEDkek9FSzvs7lvJyZ1bm0rpsyjKL2vMpMO7arAejVJm_SDnheUFaPyq_dmlF5V6DoIJHzRA6hQanqiHXA.jXKhaqFcxjsMZVN7lb4dpIN8aYF7SWKo5U4l7TqQe3H6CMlarbldvjy6YgPBitKAl6_11YQ5tGiH1ZvTGCJQOS2lN25_WqqIN9bvHSQhSFIfgDjYyP0C4rPC0PaRXP7uX.XqQCP2s0ea5WtAwMj.KPmDfApvsYYWspxzAVbjLeNOsUTqXa9vdUkvqnYkD5TTib.B7d0hrl9AugSEbhQ20hOP0gWPJDtFLTwJNkIdnODwUkNKPkTanw.sX5R99_7CQdw9Ep0h3GeB.bF91v1rUz.EhoL81Ed3sX_VQizZSPTY7OExwfZJt8tIS38x_xm3lKiDYT4cAbSoxeNEa3JuhNCkdbDl1jYknfmiiNqLq.DTZ8IDEtKs.Pystpojyp3_.XlgmYGvhFqmjJZIFV3BMpKxu4WfNb1UElRxSGjr1jtCoVSpubuB3A1XilCxd31L9RbrFE8soaICdDJVLIJeKACzLvD1IetPSy9L28JjRCbC_NruGmtHhtverim930BlWU4VD6kklRIYIR54vQEUe1_cYbR_WMXqmslpw29f0QQ1LXSdCUMs5pAukB6XmYpG9nmiq71_CQbuGORgIEHtaVmt2xwyAGA5buh3dodc297mEWbRq9UtUY06Jsw6zAvCJfhcM6HNlSy8QNI7Gr8b4wtu9cT4v6J7aFdbxCYxRqY.QYZKGW27v4e27I44daI8kAT_iUFmnNk36a1BO1CRYiF2yB.kJlt9RlUblh8rIvEnt7W0gMqJog4NpNHrjfqYeKZcAOickMnTH8i6A.GfdZLkpOqk.JuMsG12dHRWLhBcbUg2zmvTLmQc_bsfrUGUvHUSvj7leAxdNl7zBsdaonXqriw.k7ciOilwLpbMhmevGalEDHdZ52QPth2ZJn1bfcOo5Dkka3D6OfHAioG4"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=917c080c5fd98333';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=Perpetual%20Onyejelem&__cf_chl_rt_tk=8zVSMHoEeOjw401ht_QoTYAXz7lTJZzcA9NEohXBiY4-1740531975-1.0.1.1-eN1fLFXkZ216lcmNfS5W9IReXbVzJC8Ek429g3p2ipg" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>