Cibiyar kula da ruwan sha na birni a Gabashin Asiya na buƙatar cikakken tsarin iskar da za a iya dawo da shi don faɗaɗawa lokaci na 4{1} - rami ɗaya na oxidation a zurfin ruwa 7.15 m. AquaSust ya ba da 1,496 Φ90 × 1000 mm TPU kyawawan bubble bututu diffusers da ƙungiyoyi 22 na firam ɗin SS304 mai dawo da iska, suna kammala shigarwa cikin kwanaki 22. Binciken hadin gwiwa na jam'iyyu guda biyar da aka gudanar bayan watanni 4 na ci gaba da aiki ya tabbatar da cikakken cancantar tsarin - da aka rubuta. Wannan binciken binciken yana tattara tushen ƙirar injiniya, iyakar wadata, tsarin lokacin shigarwa, da sakamako mai ƙaddamarwa.

image

 

 

Fagen Aikin

 

 

Aeration shine mafi girman kuɗin makamashi guda ɗaya a cikin kowane tsarin kula da ruwan sharar halittu, lissafin kuɗi50-70% na jimlar shuka OPEX(ma'auni na masana'antu, daidai da bayanai a cikin * Metcalf & Eddy: Injiniyan Wastewater *, 6th ed.). Don shukar da ke fuskantar faɗaɗa ƙarfin lokaci, zaɓin nau'in shigar da iska yana ɗaukar sakamakon da ya wuce tsawon rayuwar aiki na sabbin kayan aikin - ba kawai ta hanyar ƙaddamarwa ba.

Wannan aikin fadada lokaci na 4 - ya ƙunshi gina rami mai oxidation tare da ƙirar zurfin ruwa.7.15 m- mai zurfi fiye da mita 4-6 na daidaitattun kwandunan iska. Babban zurfin nutsewar ruwa yana inganta daidaitaccen daidaitaccen isar da iskar oxygen (SOTE), amma kuma yana ƙara rikitar jiki na kowane taron kiyayewa na gaba idan an ƙayyade ƙayyadaddun masu watsawa na ƙasa{4}}.

Abokin ciniki da mashawarcin ƙira ya zaɓi acikakken dawo da tsarin iskasaboda dalilai guda uku masu yawa:

1. Oxidation rami sanyi tare da submersible mixers:Madaidaicin grid na ƙasa zai buƙaci daidaitawar tsari na dindindin tare da ƙirar sharewar mahaɗa. Tsarin firam ɗin da za a iya dawo da shi yana ba da damar ɗaukar taro na iska daga hanyar mahaɗa yayin kiyayewa - kiyaye amintaccen izinin aiki ba tare da rufe tsari ba.

2. Tsare-tsare na dogon lokaci{1} OPEX:Dangane da * US EPA Fine Pore Aeration Design Manual* (EPA/625/1-89/023), lalatar diffuser shine babban direban farashi na rayuwa. Ƙayyade damar dawowa daga matakin ƙira yana kawar da buƙatar magudanar ruwa a duk abubuwan da suka faru na sabis na gaba.

3. 4th{1}}Maganin fadada lokaci:Ana sa ran ayyukan lokaci na 5 na gaba. Tsarin da za a iya dawo da shi yana adana cikakken sassaucin aiki yayin kowane aikin gini kusa da - ana iya ɗagawa, dubawa, da kuma sake shiga ciki ba tare da tsangwama ba.

 

 

Zabin Bubble Bubble Diffuser Selection & Fassarar Fasaha

 

 

Cikakken iyakan samar da wannan aikin ya ƙunshi nau'ikan kayan aiki guda 6 da 15+ ƙayyadaddun fasaha na mutum ɗaya. Dukkanin abubuwan masana'anta sun kasance masana'anta{3}} an kera su kuma an gwada su kafin jigilar kaya.

 

Fine Bubble Diffuser- 90×1000 mm TPU Membrane

 

Siga

Ƙayyadaddun bayanai

1

2

Yawan

raka'a 1,496

Abun ciki

Shigo da TPU (thermoplastic polyurethane)

Girma

Φ90 × 1,000 mm

Micro{0}} ƙidaya pore

Mafi girma ko daidai da 25,000 pores kowace raka'a

Kewayon kwararar iska (kowace raka'a)

7.5 - 14 m³/h (tsarin ƙira: 6 - 18 m³/h)

Kaurin ƙwayar cuta

0.70 ± 0.05 mm

Layin ciki

PP ko ABS / UPVC (1.0 MPa rated)

Kumfa diamita

1-2 mm

SOTE @ zurfin ruwa 8.2m (ruwan tsafta)

Yafi ko daidai 35%

SAE (Tsarin Ƙirar iska)

Yafi ko daidaita 7.5kO₂/kW·h

SOTR (kowace raka'a)

Yafi ko daidaita 0.85 kgO₂/h

Rashin juriya

Kasa da ko daidai da 5,500 Pa

3-shekara rage lalacewar membrane

Kasa da ko daidai 8%

 

>Ƙimar SOTE da SAE waɗanda aka auna ƙarƙashin yanayin ruwa mai tsabta a zurfin zurfin ruwa na 8.2 m, masu daidaitawa tare da ka'idodin ma'aunin iskar oxygen na EN 12255-15.

 

Tsarin iska mai dawo da SS304

 

Bangaren

Ƙayyadaddun bayanai

Yawan

Kayan abu

Riser pipe

D159 × 3.4 mm

176 m duka

Saukewa: SS304

Rukunin firam ɗin da za a iya dawo da su ( taro na kan rarraba iska)

Babban bututu D159 × 3.4mm + reshe bututu D110 × 3.0mm

kungiyoyi 22

Saukewa: SS304

Magudanar ruwa + magudanar ruwa ta hannu

DN20

22 sets

Saukewa: SS304

Bututu clamps

Don daidaita duk girman bututu

Cikakken cikawa

Saukewa: SS304

 

Kayayyakin Tallafawa

 

Abu

Bayani

Yawan

Na'urar wanki ta wayar hannu{0}

Acid wankin keken + dosing famfo

1 saiti

 

!AquaSust SS304 da za a iya dawo da rukunin firam ɗin iska kafin shigarwa a cikin rami mai iskar oxygen

*Alt: SS304 mai iya dawo da firam ɗin iska - 22 ƙungiyoyi Φ90 tube diffuser oxidation ditch case*

 

 

Tushen Zane Injiniya

 

 

Dual- Zane-zanen Buga Duty Point Design

 

An ƙirƙira tsarin don yanayin aiki daban-daban guda biyu don dacewa da dabarun ƙaddamar da lokaci:

 

Siga

Single - Aikin Buga

Dual - Aikin Buga

Jimillar kwararar iska

12,000 m³/h

24,000 m³/h

Ƙididdigar diffuser

raka'a 1,496

raka'a 1,496

Gudun iska a kowace naúrar (ƙididdiga)

~8 m³/h

~16 m³/h

Zane iyakar iska

6 – 18 m³/h

6 – 18 m³/h

 

Duk abubuwan da ake buƙata suna faɗuwa a cikin kewayon ƙimar iska ta Φ90{5}} 1000 bututu diffuser (7.5 – 14 m³/h maras kyau; 6 – 18 m³/h ambulaf ɗin ƙira), yana mai tabbatar da ci gaba da aiki ba tare da matsananciyar matsi ba a mafi girman ƙarfin busa.

 

Diffuser Rufe Geometry

 

Kowane ɗayan raka'a 1,496 masu rarrabawa an sanya su mafi ƙarancin yanki na sabis na mutum ɗaya naYa fi ko daidai da 1.75m2a cikin oxidation ramukan sawun. An ƙididdige wannan yawan ɗaukar hoto don isar da narkar da iskar oxygen iri ɗaya a cikin ƙetaren yanki mai iska{1}, guje wa fitattun tashoshi masu gudana waɗanda zasu rage ƙimar nitrification a ƙimar kwarara mai yawa.

  • Zurfin ruwan tanki:7.15 m
  • Diffuser tsayin shigarwa sama da bene na tanki:0.40 m
  • Ingantacciyar nutsewa:6.75 m(Rukunin ruwa mai aiki sama da fuskar diffuser)
image

 

Me yasa Za'a iya Dawowa Cikakkun a cikin Ramin Oxidation?

 

Ramin Oxidation yana gabatar da takamaiman ƙalubalen injiniya:Submersible mixers (tashar kwarara propellers)dole ne a kula da hanyoyin share fage ba tare da toshewa ba ta yankin iska. Tsayayyen ƙasa{1}} grid ɗin da aka ɗora yana haifar da tsangwama ta dindindin tare da sabis na mahaɗa da sauyawa.

Cikakken ƙirar firam ɗin da za a iya dawo da shi yana warware wannan rikici da tsari. Kowace rukunin firam ɗin 22 yana ɗagawa a tsaye azaman cikakkiyar naúrar. Samun shiga, dubawa, ko musanya na iya ci gaba tare da cire haɗin iska - ba tare da matse tashar ba, ba tare da damun gadon sludge ba, kuma ba tare da rufe tsari ba. Wannan daidaituwar sararin samaniya tsakanin iska da kayan haɗaɗɗun kayan aiki shine tushen aikin injiniya na farko don cikakken bayani dalla-dalla akan wannan aikin.

Φ90 TPU tube diffuser shigarwa an gama gani a cikin rami mai iskar oxygen - 1496 raka'a AquaSust

 

 

Shigarwa & Tsarin Lokaci

 

 

Dukkanin aikin daga tashi daga masana'anta zuwa kammala shigarwa an aiwatar da shi a cikiQ1 2026, ya kai kusanKwanaki 22 na kan -aikin rukunin yanar gizo.

 

Jerin Mahimmanci

 

Muhimmi

Lokaci

Ayyuka

Aiwatar da masana'anta

Farkon Q{0}}

Karɓar masana'anta, marufi, da jigilar kaya

Tsarin tsari & isar da bututu

Mako na 1, Q{1}

SS304 firam ɗin da za a iya dawo da su, bututun tashi, taron magudanar ruwa na condensate sun isa wurin; dubawar unboxing wanda abokin ciniki da wakilai masu kulawa suka kammala

Isar da Tube diffuser

Mako na 2, Q{1}

1,496 Φ90 × 1000 TPU tube diffuser raka'a sun isa wurin; an kammala binciken cire akwatin

An gama shigarwa

Ranar 22, Q{1}

An shigar da duk ƙungiyoyin firam ɗin 22; duk 1,496 diffusers da aka saka kuma an gama isar da haɗin kai{3}

 

Iyakar Gudanarwa

 

A kan{0}Ayyukan ƙaddamar da rukunin yanar gizon da ƙungiyar injiniyan AquaSust ta yi sun haɗa da:

  • Gwajin zubewar iska:Cikakken gwajin matsa lamba na pneumatic na tsarin a matsa lamba a cikin duk ƙungiyoyin firam 22 da hanyoyin sadarwa 1,496
  • TAbbaci:Narkar da ma'aunin iskar oxygen a wurare da yawa na tanki don tabbatar da rarraba iri ɗaya a ƙarƙashin sharuɗɗan aikin busa guda ɗaya- da biyu{1}
  • Gwajin ingancin datti:Maganin halitta yana zubar da samfurin ingancin ruwa da bincike akan sigogin fitarwa na ƙira
  • Haɗaɗɗen ƙaddamarwa:Haɗe-haɗen busawa{0} zuwa{1}}masu rarraba iska, gwajin aikin magudanar ruwa, da tabbatar da sharewar mahaɗa.
  • Karɓar jam'iyyu da yawa{{0}:Akan -Duba shafin da sanya hannu{1}} ta wakilin abokin ciniki da mai kula da mazaunin

Ba a buƙatar magudanar tanki a kowane mataki na shigarwa ko ƙaddamarwa. Ramin oxidation ya kasance yana aiki a cikin nazarin halittu a duk lokacin shigarwa ta hanyar keɓe yankin da aka tsara.

 

 

Buga{0}}Tabbatar da ƙaddamarwa - 4-Sakamakon Aiki na Watan

 

 

Mafi tsananin inganci a cikin wannan aikin bai zo a lokacin shigarwa ba, ammaWatanni 4 cikin ci gaba da aiki.

 

Biyar -Duba Haɗin gwiwar Jam'iyya

 

Dangane da daidaitaccen tsarin gudanarwa na ayyukan samar da ababen more rayuwa na birni, an gudanar da binciken haɗin gwiwa na yau da kullun tare da ƙungiyoyi biyar masu alhakin da suka halarta:

1. Ma'aikacin shuka (abokin ciniki)

2. Mai kula da gine-gine / injiniyan mazaunin

3. Mashawarcin zane

4. Hukumar bincike mai zaman kanta

5. Ƙungiyar injiniya ta AquaSust

Tsarin dubawa ya haɗa da agwajin daga kai tsaye: Ƙungiyoyin firam ɗin da aka zaɓa an ɗaga su cikin jiki daga tankin aiki zuwa saman - tare da ramin oxidation a cikin aikin nazarin halittu na rayuwa - don ba da damar binciken kwamitin kwararru na:

  • Mutuncin Membrane (babu hawaye, nakasawa, ko ɓacin rai wanda ya wuce haƙurin ƙira)
  • Yanayin Orifice Diffuser (babu toshewa ko tsarin rufewa na al'ada)
  • SS304 frame yanayin tsarin (ba lalata, nakasawa, ko fastener gazawar)
  • Hanyoyin haɗin bututun iska (babu yabo ko lalacewar haɗin gwiwa)

Sakamako: Duk sharuɗɗan dubawa sun cika. Kwamitin ƙwararru ya tabbatar da cikakken cancanta tare da rakodin ƙarancin sifili.

Wannan gwajin dawo da kai tsaye - da aka gudanar a ƙarƙashin yanayin aiki na gaske bayan watanni 4 na ci gaba da sabis - shine tabbataccen nunin aikin injiniya wanda cikakken tsarin isar da iskar da za a iya dawo da shi ke bayarwa akan ainihin ƙirar sa: mai isa, ba{3}mai rugujewa ba tare da katsewa ba.

Buga{0}} tabbatar da taswirar ɗagawa - firam ɗin da za a iya dawo da shi daga ramin iskar oxygen

*Alt: tsarin iskar iska 4-watan wata{2}} tabbatarwa mai aiki - SS304 mai iya dawo da iskar firam ɗin gwajin ɗagawa*

 

 

Me yasa Za'a iya Dawowa Cikakkun Jiragen Sama don WWTP na Municipal?

 

 

Wannan aikin yana tabbatar da ƙimar dabara guda uku na ƙayyadaddun tsarin iskar da za a iya dawo dasu don kula da ruwan sha na birni:

Sifili Downtime don Kulawa na gaba

Gwajin ɗagawa kai tsaye da aka gudanar a binciken watanni 4{2} ya tabbatar da cewa ana iya ɗaga gabaɗayan taron iskar iska daga tanki mai aiki ba tare da rufe tsari ba. Don tsaftace membrane na gaba, maye gurbin mai watsawa, ko zagaye na duba tsarin, ana auna abubuwan da suka faru a cikin sa'o'i - ba kwanakin 10-15 na tanki ba{6}}magudanar ruwa{7}} tsarin da aka dora ƙasa (alamar masana'antu, daidai da bayanan aiki na WEF MOP 8 don kwatankwacin kayan aikin birni).

Kawar da Ciwon Tanki da Farashin Magudanar ruwa

Kowane taron magudanar ruwa na tanki na ƙasa na al'ada{0}}tsararrun tsarin yana buƙatar cire ruwa na inji, daidaitawar cire sludge, ƙayyadaddun izinin shigar da sarari, da kuma bayan{2}}samar da tsarin nazarin halittu-kwarewa. Don rami mai zurfi na iskar oxygen a zurfin ruwa na 7.15 m, ana haɓaka waɗannan farashin ta ƙarar da ke ciki. Cikakken tsarin da za a iya dawo da shi yana kawar da wannan nau'in farashi gaba ɗaya don watsa shirye-shirye{7}} abubuwan da suka shafi kiyayewa a cikin rayuwar tsarin aiki.

Dogon - Rage Ragewar OPEX

Haɗin sifili{0}} kula da magudanar ruwa da ƙayyadaddun rufin lalatar membrane (Kasa da ko daidai da 8% sama da shekaru 3) yana ƙirƙira ƙirƙira mai ƙima, ƙaramin{0}} bambance-bambancen bayanin farashin aiki. Masu gudanarwa na iya tsara abubuwan da aka tsara na kiyayewa ba tare da haɗarin bin ka'ida ba, rushewar tsarin ilimin halitta, ko fallasa kasafin kuɗi na gaggawa. Rahoton da aka ƙayyade na SAEYafi ko daidaita 7.5kO₂/kW·hyana tabbatar da cewa tsarin yana kula da ingancin makamashi a cikin sigogin ƙira a cikin lokacin garanti.

 

 

FAQ

 

 

Tambaya: Menene cikakken tsarin iskar da ake iya dawowa?

A: Tsarin iskar da ake iya dawowa da shi yana haɗa dukkan sassan manyan bututun rarraba iska ({0}}), bututun reshe, masu ɗorawa, da masu tarwatsa bututun membrane - cikin ƙayyadaddun tsarin tsarin kowane rukunin yanki na iska. An ƙera gabaɗayan taron ne don injin ƙira -taimakon hakar a tsaye daga tanki a matsayin raka'a ɗaya, ba tare da rarrabuwar ɓangarori ba kuma ba tare da magudanar tanki ba. A cikin wannan aikin, an shigar da irin waɗannan ƙungiyoyin firam guda 22 - kowanne ɗaya ɗauke da banki na Φ90×1000 TPU tube diffusers - a cikin rami mai zurfin oxidation mai zurfin mita 7.15, sannan an yi nasarar fitar da su kuma an sake su{12}} yayin gudanar da bincike kai tsaye bayan sabis na watanni 4. Bincika abubuwanAquaSust tube diffuser jerindon ƙayyadaddun samfur na yanzu.

Tambaya: Yaya tsawon lokacin shigarwa ke ɗauka don tsarin diffuser mai raka'a 1,500?

A: Don wannan faɗaɗawar WWTP na birni na huɗu{1}, ƙungiyar injiniyoyin AquaSust sun kammala cikakkiyar shigarwa na 1,496 Φ90 × 1000 TPU tube diffusers da 22 SS304 da za'a iya dawo dasu ƙungiyoyi a cikinKwanaki 22daga isar da rukunin farko zuwa sa hannun shigarwa{0}}. Wannan layin lokaci ya haɗa da dubawar buɗe akwatin, taron firam, hawan mai watsawa, iska{2}} hanyoyin samar da bututu, cikakken gwajin matsananciyar huhu, tabbatar da DO, da haɗin gwiwar ƙungiyoyi masu yawa{3}. Yanar Gizo{5} takamaiman dalilai - juzu'i na tanki, hanyar shiga crane, daidaita ɗakin busa - za su yi tasiri akan lokutan wasu ayyuka; Injiniyan AquaSust zai samar da takamaiman aiki - takamaiman jadawali a matakin zance.

Q: Menene bambanci tsakanin SOTE a 8.2 m vs 6 m zurfin ruwa?

A: Daidaitaccen Canjin Oxygen Canja wurin (SOTE) yana ƙaruwa tare da zurfin nutsewa saboda ginshiƙin ruwa mai zurfi yana ba da hanyar tuntuɓar kumfa mai tsayi da mafi girman matsin lamba na hydrostatic, duka biyun suna haɓaka ƙimar iskar oxygen. Φ90×1000 TPU tube diffusers da aka kawo don wannan aikin ana ƙididdige su aSOTE Mafi Girma ko daidai da 35% a zurfin ruwa 8.2 m(gwajin ruwa mai tsafta). A mafi yawan zurfin kwandon ruwa na 6m, ƙimar SOTE don kwatankwacin masu watsa bututu yawanci suna faɗuwa a cikin kewayon 28-32% (ma'auni na masana'antu, daidai da EPA/625/1-89/023 abubuwan gyara ruwa). Ƙayyadaddun kwandon iska mai zurfi - kamar yadda yake cikin wannan aikin a zurfin zurfin 7.15 m - don haka yana ba da ingantaccen ingantaccen isashshen iskar oxygen kowace naúrar shigar da makamashin iska ba tare da canza nau'in mai watsawa ko ƙayyadaddun busa ba.

Tambaya: Me yasa zabar TPU mai kyau bubble bubble diffuser membrane akan EPDM?

A: TPU (thermoplastic polyurethane) membranes suna ba da haɗin gwiwar injina da juriya na sinadarai waɗanda suka dace da ci gaba da aikin iska na birni. A cikin wannan aikin, an zaɓi ƙayyadaddun membrane na TPU don daidaiton girman sa a ƙarƙashin ɗorawa na matsa lamba na cyclical da kuma rubuce-rubucen ƙarancin lahani dangane da membranes na EPDM na al'ada a ƙarƙashin yanayin aiki mai kama da aiki (alamar masana'antu). A membrane lalata rufinKasa da ko daidai da 8% sama da shekaru 3ƙayyadaddun don wannan aikin shine anka aikin kwangila na garantin tsarin shekara 3{3} da garantin membrane na shekaru 5. Membran EPDM ya kasance madadin ingantacciyar hanyar shigarwa mai zurfi; don kwatankwacin daidaitawar faifan diski tare da membranes na EPDM, dubamadadin diski diffusershafi.

Tambaya: Za a iya shigar da iskar da za a iya dawo da ita a cikin rami mai oxidation tare da mahaɗa?

A: Ee - kuma wannan shine ainihin tsarin da aka tura cikin wannan aikin. Babban abin da ake buƙata na aikin injiniya shine kiyaye isasshiyar share fage tsakanin sawun firam ɗin da za a iya dawo da shi da hanyar share fage. A cikin wannan rami oxidation, ƙungiyoyin firam ɗin 22 waɗanda za a iya dawo dasu an sanya su don tabbatar da amintaccen nisan aiki daga tashar mai yuwuwa -masu haɗa ruwa a cikin duk saitunan aiki. Hakanan an tabbatar da hanyar cirewa a tsaye na kowane rukunin firam don share kayan hawan mahaɗa yayin jerin ɗagawa. Ana warware wannan haɗin kai yayin lokacin ƙira; Ƙungiyar injiniya ta AquaSust tana aiwatar da tabbatarwa a matsayin wani ɓangare na aikin{7}} takamaiman nazarin zane kafin ƙirƙira. Bitar daSS304 abubuwan da aka dawo da iska mai iskadon ƙayyadaddun tsari.

 

 

Kammalawa

 

 

Wannan fadada WWTP na birni na huɗu{1} a Gabashin Asiya yana nuna cewa acikakken dawo da bututu diffuser shigarwa- lokacin da aka ƙayyade daidai, ƙirƙira, da kuma ba da izini - yana ba da tabbataccen aiki a ƙarƙashin yanayin aiki na gaske. Mahimmin sakamakon da aka tabbatar:

  • 1,496 Φ90×1000 TPU tube diffuserskuma22 SS304 ƙungiyoyin firam ɗin da za a iya dawo dasushigar a cikin kwanaki 22 ba tare da buƙatar magudanar tanki ba
  • SOTE Mafi girma ko daidai da 35% a zurfin ruwa na 8.2 m, SAE Mafi girma ko daidai da 7.5 kgO₂/kW·h an tabbatar a cikin sigogin ƙira
  • Biyar -Biyar binciken haɗin gwiwa bayan watanni 4 na ci gaba da sabis: duk sharuɗɗan sun cika, an ƙididdige gazawar sifili
  • Gwajin ɗagawa kai tsaye ya tabbatar da dawo da aiki a ƙarƙashin yanayin aiki - ma'anar ma'anar wannan nau'in tsarin

Ga ma'aikatan WWTP na birni suna shirin sabon gini ko faɗaɗa iya aiki, yanayin aikin injiniya don cikakken isar da iskar da za a iya dawo da shi ya dogara ne akan farashin rayuwa, ba tsadar babban birnin kawai ba. Ikon yin hidimar diffusers 1,496 ba tare da zubar da rami mai zurfin oxidation mai zurfin mita 7.15 - da aka tabbatar a cikin wannan aikin bayan watanni na sabis na gaske - shine fa'idar aiki wanda ƙasa{6}maɗaukakin madadin ba zai iya yin kwafi ba.

Shirya don kimanta cikakken tsarin isar da iskar da za a iya dawo da shi don aikin ku?

Bincika abubuwan AquaSust tube diffuser jerindon cikakkun bayanai na fasaha da zaɓuɓɓukan sanyi. BitaSS304 abubuwan da aka dawo da iska mai iskadon cikakkun bayanai na kayan aiki da tsarin. Don madadin faifan diski{1}, dubamadadin diski diffusershafi. Ziyarciaeration diffuser bayyanidon cikakken kwatanta kewayon.

Don neman aikin - takamaiman aikin injiniya ko magana, tuntuɓi AquaSust

Injin Injiniya kai tsaye aaquasustfactory.com.