Ke ʻano hana electromagnetic domain alapine (frequency domain) ma Geophysics
Pendahuluan
He lālā ʻepekema ʻo Geophysics e aʻo ana i nā ʻano kino o ka Honua a me kona wahi e puni ana ma o nā ʻano hana o ka physics a me ka makemakika. ʻO kekahi ʻano hana koʻikoʻi i ka geophysics ʻo ia ke ʻano electromagnetic (EM), kahi e hoʻohana ai i nā ʻano electromagnetic o nā mea subsurface e loaʻa ai ka ʻikepili pono a me ka ʻike e pili ana i ke ʻano o loko o ka Honua. Hoʻohana ʻia kekahi mau ʻano like ʻole o nā ʻano hana electromagnetic i ka geophysics, ʻo kekahi o ia mau mea ʻo ke ʻano Frequency Domain Electromagnetic (FDEM).
Nā Kumumanaʻo Kumu o ke ʻAno Hana Electromagnetic o ka Frequency Domain
Hoʻokumu ʻia ke ʻano hana Frequency Domain Electromagnetic (FDEM) ma luna o nā loina kumu o ka electromagnetics, ʻoiai ka pilina ma waena o nā kahua electromagnetic a me nā mea conductive ma lalo o ka ʻili o ka Honua. Ma kēia ʻano hana, hoʻopuka ʻia kahi kahua electromagnetic e kahi kumu, ʻo ia hoʻi he coil a antenna paha, kahi e hoʻopuka ai i nā ʻokoʻa alapine kikoʻī ma ka lewa a me ka manawa (ka frequency domain).
I ka laha ʻana o kēia kahua electromagnetic ma lalo o ka ʻili o ka Honua, launa pū ia me nā mea honua nona nā ʻano conductivity like ʻole. ʻO kēia launa pū ʻana ke kumu o ka hoʻokumu ʻia ʻana o nā kahe eddy i loko o ka mea conductive, kahi e hoʻololi ai i ke kahua electromagnetic i loaʻa e ka coil receiver. Ma ka nānā ʻana i kēia mau loli kahua ma nā alapine like ʻole, hiki iā mākou ke loaʻa ka ʻike e pili ana i ka hoʻolaha ʻana a me ka conductivity o nā mea subsurface.
ʻO ke Kumumanaʻo a me ke ʻano hana FDEM
Nā Kānāwai o Maxwell a me ke Kaulike o Helmholtz
Hoʻokumu ʻia ke ʻano FDEM ma nā kānāwai kumu o ka electromagnetism i hoʻomalu ʻia e nā kaulike a Maxwell. Hāʻawi nā kaulike a Maxwell i ka pilina ma waena o nā kahua uila a me nā kahua magnetic , a pehea e launa pū ai kēia mau kahua me nā uku uila a me nā au. Ma ke ʻano o FDEM, hoʻololi pinepine ʻia nā kaulike a Maxwell i nā kaulike Helmholtz no ka nānā hou aku.
ʻO ke kaulike Helmholtz kahi hoʻololi Fourier o nā kaulike a Maxwell e hoʻomaʻalahi ana i nā helu ma ka hoʻoneʻe ʻana i ka pilikia mai ka ʻāpana manawa a i ka ʻāpana alapine (frequency). Ma kēia ʻano, wehewehe ke kaulike Helmholtz pehea e laha ai kahi kahua electromagnetic ma o kahi mea alakaʻi:
\[ \nabla^2 \mathbf{E} + k^2 \mathbf{E} = 0 \]
kahi ʻo \(\mathbf{E}\) ke kahua uila a ʻo \(k\) ka helu nalu paʻakikī e hilinaʻi ana i ke alapine hoʻokele a me nā waiwai o ka waena.
Pane Alapine (Frequency Response) a me ka Wehewehe ʻIkepili
I ka hana maoli, pili ke ʻano FDEM i ke ana ʻana i ka pane alapine (frequency) o ke kahua electromagnetic i hana ʻia e kahi kumu. Hoʻopaʻa pinepine ʻia kēia pane ma ke ʻano he hana o ka amplitude a me ka pae o ke kahua i loaʻa ma nā alapine like ʻole. Hāʻawi kēia ʻike i ka ʻike i ka hoʻolaha ʻana o ka conductivity ma lalo o ka ʻili o ka Honua. ʻO ke conductivity kiʻekiʻe e hana i nā pane amplitude ikaika a me nā loli pae koʻikoʻi ma nā alapine kikoʻī.
A laila ua wehewehe ʻia ka ʻikepili i loaʻa mai ka noiʻi FDEM me ka hoʻohana ʻana i nā kumu hoʻohālike makemakika a me ka hoʻohuli helu e hana i nā ʻikepili conductivity subsurface. ʻAe kēia kaʻina hana i ka hoʻoholo ʻana i ke ʻano o ka papa, ka ʻike ʻana i nā mea mineral, a me ka ʻike ʻana i ka wai honua a i ʻole nā waihona hydrocarbon.
Ka Hoʻohana ʻana o ke ʻAno FDEM
Loaʻa i nā ʻano hana Electromagnetic ka laulā o nā noi ma nā ʻano geophysical a me nā ʻano kaiapuni like ʻole. ʻO kekahi o nā noi nui:
I ka ʻoihana mining, hoʻohana ʻia ʻo FDEM no ka ʻimi ʻana i nā waihona mineral metala. ʻAe kēia ʻano hana i ka ʻike ʻana i nā mea conductive e like me nā waihona sulfide waiwai nui. Ma ka hoʻoholo ʻana i ka hoʻolaha ʻana o ka conductivity, hiki i nā mea noiʻi ke ʻike i nā wahi me ka hiki ke loaʻa nā mineral kiʻekiʻe, e hōʻemi ana i nā kumukūʻai ʻimi a me ka manawa.
Ka Nānā ʻana i ke Kaiapuni
He mea pono nō hoʻi ka FDEM i ka nānā ʻana i ke kaiapuni, ʻoiai hoʻi i ka ʻike ʻana i ka haumia ʻoihana a me ke kahe ʻana o nā mea weliweli ma lalo o ka ʻili. No ka laʻana, hiki i kēia ʻano hana ke ʻike i nā leaka o ka ʻaila a i ʻole nā kemika ʻē aʻe mai nā pahu mālama a i ʻole nā paipu hoʻolaha. Hāʻawi ka ʻikepili conductivity i kahi hōʻailona o nā wahi i haumia a kōkua i ka hoʻolālā hoʻoponopono.
ʻIke wai honua
I ka hydrogeology, hoʻohana ʻia ka FDEM e palapala i nā ʻāpana aquifer a ʻike i nā ala kahe o ka wai honua. Hāʻawi kēia ʻano hana i ka ʻike koʻikoʻi e pili ana i ka hoʻolaha ʻana a me ka maikaʻi o ka wai honua, e kākoʻo ana i ka hoʻokele waiwai wai hoʻomau. Ma ka palapala ʻana i ka conductivity subsurface, hiki i nā mea noiʻi ke ʻike i nā wahi i loaʻa paha ka wai maʻemaʻe a haumia paha.
Nā Pōmaikaʻi a me nā Palena o FDEM
loaa
1. Hoʻonā Kū Kiʻekiʻe: Hāʻawi ka FDEM i ka hoʻonā kū maikaʻi i hoʻohālikelike ʻia me nā ʻano ana electromagnetic ʻē aʻe, e ʻae ana i ka hoʻoholo pololei ʻana i nā waiwai mea ma kahi hohonu i hāʻawi ʻia.
2. ʻAʻole Hoʻouka: E like me nā ʻano hana geophysical āpau, ʻo FDEM kahi ʻenehana ʻaʻole hoʻouka ʻia e pono ʻole ai ka ʻeli ʻana a i ʻole ka ʻeli ʻana e loaʻa ai ka ʻike e pili ana i nā hale ma lalo o ka ʻili.
3. Hohonu Noiʻi: Me ka hoʻohana ʻana i nā alapine kiʻekiʻe a me haʻahaʻa, hiki ke hoʻohana ʻia ʻo FDEM e noiʻi i nā hohonu like ʻole, mai ka papa ʻili a i kekahi mau haneli mika ma lalo o ka honua.
Nā Palena
1. Ke komo ʻana mai nā mea ʻilikai: Hiki i nā ʻano hana i hana ʻia e ke kanaka a i ʻole nā mea alakaʻi kokoke i ka ʻilikai ke komo i nā ana a hōʻemi i ka pololei o ka ʻikepili.
2. Ka ʻIkepili i nā Kūlana Lepo: Hiki i nā mea e like me ka makū o ka lepo, ke kū'ē ʻana o ka pōhaku, a me nā ʻano like ʻole ke hoʻopilikia i nā hopena ana, no laila pono ka mālama a me ka ʻike i ka wehewehe ʻana.
3. Ka Paʻakikī o ka Wehewehe ʻana: Pono pinepine ka ʻikepili FDEM i kahi kaʻina hana hoʻohuli paʻakikī e hoʻololi i nā ana o ke kahua electromagnetic i ʻike pono e pili ana i nā ʻano o lalo o ka honua. Pono kēia i ka hoʻohana ʻana i nā polokalamu kūikawā a me ka ʻike hohonu i ka geophysics.
Ka Hoʻomohala ʻenehana a me ka Wā e hiki mai ana o FDEM
Me ka holomua o ka ʻenehana i nā mea hana geophysical a me ka helu ʻana, ke hoʻomau nei ke ʻano FDEM i ka hoʻomaikaʻi ʻana i ka pololei a me ka pono. ʻO ka hoʻomohala ʻana o nā mea ʻike a me nā antennas ʻoi aku ka naʻauao, a me nā algorithms inversion ʻoi aku ka paʻakikī, e ʻae ai i ka loiloi ʻikepili hohonu a pololei.
Eia kekahi, ʻo ka hoʻohui ʻana i ka FDEM me nā ʻano hana geophysical ʻē aʻe, e like me ka Ground Penetrating Radar (GPR) a i ʻole nā ʻano hana seismic, hāʻawi i nā hopena piha aʻe i nā haʻawina subsurface. ʻO kēia hui pū ʻana o ka ʻikepili mai nā kumu he nui e hoʻoikaika i nā wehewehe ʻana a hiki ke hoʻopaʻa palapala ʻāina pololei no nā ʻano noi like ʻole.
Ka hopena
He mea hana waiwai nui ke ʻano hana Frequency Domain Electromagnetic (FDEM) i ka geophysics hou, me nā noi ākea i ka ʻimi ʻana i nā minerala, ka nānā ʻana i ke kaiapuni, a me ka hydrogeology. ʻOiai kona mau palena, ʻo kona mau pono i ka hoʻonā kū pololei, ka hohonu o ka noiʻi ʻana, a me ka non-invasiveness e hoʻolilo iā FDEM i koho alakaʻi no nā ʻano haʻawina subsurface like ʻole.
Me ka hoʻomau ʻana o ka hoʻomohala ʻana o ka ʻenehana a me nā ʻano hana loiloi, manaʻo ʻia ʻo FDEM e hoʻokani i kahi kuleana koʻikoʻi i ka hoʻomaopopo ʻana a me ka hoʻohana ʻana i nā kumuwaiwai o lalo o ka Honua me ka maikaʻi a me ke kūpaʻa.
