²é¿´: 646  |  »Ø¸´: 4
µ±Ç°Ö÷ÌâÒѾ­´æµµ¡£

ttpig2005

[½»Á÷] EiÖÐÓ¢ÎÄժ׫д½Ì³Ì

Ï£Íû¶Ô´ó¼ÒÓÐÓá£
EiÎÄÕªÒªÇó
ÃÀ¹ú¹¤³ÌË÷ÒýEiΪ¶þ´ÎÎÄÏ×£¬Êô¼ìË÷Êý¾Ý¿â£¬¿¯µÇµÄÌõÄ¿ÄÚÈÝÓÐÌâÃû¡¢×÷Õß¡¢Ó¢ÎÄÎÄÕª¡¢²Î¿¼ÎÄÏ׵ȵȡ£Òò¶þ´ÎÎÄÏ×ÎÞÈ«ÎÄÐÅÏ¢£¬ËùÒÔÎÄÕªµÄÖÊÁ¿·Ç³£ÖØÒª¡£Ò»·½Ãæ¼ìË÷Êý¾Ý¿âÒªÒÀ¾ÝÎÄÕªµÄÖÊÁ¿À´¾ö¶¨¸ÃÎÄÕÂÊÇ·ñ±»ÊÕ¼£»ÁíÒ»·½Ãæ¶ÁÕßÒª¸ù¾ÝÎÄÕªÌṩµÄÐÅÏ¢¿¼ÂÇÊÇ·ñÔĶÁ¡¢ÒýÓÃÔ­ÎÄ£¬ÈçÄܱ»ÀûÓ㬲ÅÄÜÌåÏÖÎÄÕµÄѧÊõ¼ÛÖµ£¬Ìá¸ßÔ­ÎĵÄÒýÓÃÆµ´Î¡£Òò´ËÏ£Íû¹ã´ó×÷Õß°´¹æ·¶ÈÏÕæ±àдӢÎÄÕªÒª¡£¾ßÌåÒªÇóÈçÏ¡£
1.¶ÔÎÄÏ×½øÐÐÖ÷Ìâ·ÖÎö£¬Í¨¹ýÎÄÕªÌåÏÖÖ÷Ìâ¸ÅÄî¡¢Ö÷ÌâÄÚÈÝµÈ¸ÃÆªÎÄÏ××îÖØÒªµÄÐÅÏ¢£¬Ê¹¶ÁÕßÔÚûÓп´µ½È«ÎĵÄÇé¿öÏ£¬Äܹ»ºÜÇå³þµØÁ˽⵽¸ÃƪÎÄÏ×µÄÖÐÐÄ˼Ïë¡£
2.Ó¢ÎÄÎÄÕªÓ¦ÓëÖÐÎÄÎÄÕªÏà¶ÔÓ¦¡£
3.ÐÅÏ¢Á¿ÒªÍêÕû£¬Äܹ»È«Ãæ°üº¬ÂÛÎĵĹؼüÐÅÏ¢£¬Ó¦°üÀ¨Èý·½ÃæÄÚÈÝ¡£
1)Ä¿µÄ£ºËµÃ÷д´ËÎÄÕµÄÄ¿µÄ¡¢ÄÚÈÝ£¬Òª½â¾öµÄÎÊÌ⣻
2)¹ý³Ì¼°·½·¨£ºËµÃ÷Ö÷Òª¹¤×÷¹ý³Ì¼°²ÉÓõķ½·¨¡¢Ô­Àí£¬Ò²°üÀ¨ÒÇÆ÷É豸¡¢±ß½çÌõ¼þ£¬Ò²°üº¬±ØÒªµÄÊý¾Ý£»
3) ½á¹û£ºµÃ³öµÄ½á¹ûºÍ½áÂÛ£¬ÈçÓбØÒª£¬Ó¦Ö¸³ö¸Ã½á¹ûºÍ½áÂÛµÄÓ¦Ó÷¶Î§ºÍÇé¿ö¡£
4.Ó¢ÎÄÎÄÕªµÄ³¤¶ÈÒ»°ã²»³¬¹ý250 words£¬²»ÉÙÓÚ150 words£¬ÓïÑÔ¼ò½à¡£²»¼ÓÆÀÂÛÓï¾ä£¬Èç¡°Ï൱ÂúÒ⡱¡¢¡°ÁîÈË¿Éϲ¡±µÈ¡£²»Ê¹ÓöàÓàµÄ´ÊÓÈç¡°¾Ý±¨µÀ¡­¡­¡±¡¢¡°´óÁ¿µÄµ÷²é±íÃ÷¡­¡­¡±¡¢¡°±¾ÎÄËù̸µÄÓйØÑо¿¹¤×÷ÊǶԹýÈ¥ÀϹ¤ÒÕµÄÒ»¸ö¼«´óµÄ¸Ä½ø¡±¡¢¡°±¾¹¤×÷Ê×´ÎʵÏÖÁË¡­¡­¡±¡¢¡°¾­¼ìË÷ÉÐδ·¢ÏÖÓë±¾ÎÄÀàËÆµÄÎÄÏס±µÈ¡£Ó¦¾¡Á¿É¾È¥µÄÖ÷Òª×Ö¾äÓУºin this paper£¬It is reported£¬Extensive investigation show that£¬The author discusses£¬This paper concerned with£¬based on the analyses conducted£¬on the above basis£¬in detail£¬briefly£¬mainly£¬here£¬in addition£¬qualitatively£¬furthermoreµÈµÈ¡£
5.¾¡Á¿¼ò»¯Ò»Ð©´ë´ÇºÍÖØ¸´µÄµ¥Ôª£¬É¾·±´Ó¼ò£¬È磺

²»Óà                                 ¶øÓÃ
      at temperature of 250¡æ to 300¡æ                 at 250¡«300¡æ
      at a high pressure of 2000 Pa                at 2000 Pa
      at high temperature of 1500¡æ                at 1500¡æ
      discussed and studied in detail              discussed
      has been found to increase                        increased
      from the experimental results,                     the results show
      it can be concluded that

6.×¢ÒâÎÄ·¨¡£Ö÷ҪΪÒÔϼ¸·½Ãæ¡£
1)ÄÜÓÃÃû´Ê×ö¶¨Óï²»ÒªÓö¯Ãû´Ê×ö¶¨ÓÀýÈ磺
ÓÃ measurement accuracy           ²»ÓÃ measuring accuracy
ÓÃ experimental results             ²»ÓÃ experiment results
2)¿ÉÖ±½ÓÓÃÃû´Ê»òÃû´Ê¶ÌÓï×ö¶¨ÓïµÄÇé¿öÏ£¬ÒªÉÙÓÃof ¾äÐÍ£¬ÀýÈ磺
ÓÃ measurement accuracy           ²»ÓÃ accuracy of measurement
ÓÃ camera curtain shutter            ²»ÓÃ curtain shutter of camera
ÓÃ equipment structure             ²»ÓÃ structure of equipment
3)¿ÉÓö¯´ÊµÄÇé¿ö¾¡Á¿±ÜÃâÓö¯´ÊµÄÃû´ÊÐÎʽ£¬ÀýÈ磺
Óà  Thickness of plastic sheet was measured.
²»ÓÃ Measurement of thickness of plastic sheet was made.
4)±ÜÃâʹÓÃÒ»³¤´®ÐÎÈÝ´Ê»òÃû´ÊÀ´ÐÞÊÎÃû´Ê¡£
5)¾¡Á¿ÓÃÖ÷¶¯Óï̬´úÌæ±»¶¯Óï̬£¬È磺A exceeds B ±È B is exceeded by A ºÃ¡£
6)×éÖ¯ºÃ¾ä×Ó£¬Ê¹¶¯´Ê¾¡Á¿¿¿½üÖ÷ÓÀýÈ磺
ÓÃ When the pigment was dissolved in dioxane , decolorization was irreversible after 10h of UV irradiation.
²»ÓÃ The decolorization in solutions of the pigment in dioxane , which were exposed to 10h of UV irradiation , was no longer irreversible.
7)ÓÃÖØÒªµÄÊÂʵ¿ªÍ·£¬¾¡¿ÉÄܱÜÃâÓø¨Öú´Ó¾ä¿ªÍ·£¬ÀýÈ磺
ÓÃ Power consumption of telephone suitching systems was determined from data obtained experimentally.
²»ÓÃ From data obtained experimentally, power consumption of telephone suitching systems was determined.
7.È¡Ïû»ò¼õÉÙ±³¾°ÐÅÏ¢¡£±³¾°ÐÅÏ¢Èç¹û¹ý³¤»òÕ¼ÎÄժƪ·ùµÄ±ÈÀý¹ý´ó£¬Ôò·´Ó³³öµÄ¾ÍÊǶÔ×÷ÕßËù×öµÄ¹¤×÷ÃèÊö¹ýÓÚÁýͳºÍ¼òµ¥¡£
8.×÷ÕßÔÚÎÄÏ×ÖÐ̸¼°µÄδÀ´¼Æ»®²»ÄÉÈëÎÄÕª¡£
9.Ê׾䲻µÃ¼òµ¥Öظ´ÌâÃûÖÐÒÑÓеÄÐÅÏ¢¡£
10.Óùýȥʱ̬ÐðÊö×÷Õß¹¤×÷£¬ÓÃÏÖÔÚʱ̬ÐðÊö×÷Õß½áÂÛ¡£
11.ÎÄÕªÖеÄËõдÃû³ÆÔÚµÚÒ»´Î³öÏÖʱҪÓÐÈ«³Æ¡£
12.ÎÄÕªÖеÄÌØÊâ×Ö·û¡£Ö÷ÒªÖ¸¸÷ÖÖÊýѧ·ûºÅ¡¢Êýѧ¹«Ê½¡¢¾ØÕó¡¢ÊýÁС¢Ï£À°×Öĸ¡¢ÉÏϽDZêµÈ¡£Ei¶Ô´ËרÃÅÓй涨£¬Ï£ÍûÔÚÎÄÕªÖо¡Á¿ÉÙÓÃÌØÊâ×Ö·û£¬ÒòΪËüÃǵÄÊäÈ뼫ΪÂé·³£¬¶øÇÒ¼«Ò׳ö´í£¬Ó°ÏìÎÄÕª±¾É«µÄ׼ȷÐԺͿɶÁÐÔ£¬Ó¦¾¡Á¿²»Ó㬸ÄÓÃÎÄ×Ö±í´ï»òÎÄ×ÖÐðÊö¡£¸ü¸´Ôӵıí´ïʽ¼¸ºõÄÑÒÔÊäÈ룬ӦÉ跨ȡÏû¡£

ÒÔÏÂÁгöÁ½ÆªÎÄÕµÄÕªÒª£º

»ùÓÚIGESÎļþÊäÈëµÄͼÐεç´Å¼ÆËã·½·¨

ÕªÒª:  ÔÚ²»Í¬²¨¶Î²»Í¬¼«»¯Ï£¬Ó¦ÓÃͼÐεç´Å¼ÆË㣨GRECO£©·¨¼ÆËãÁËijģÐÍµÄ¸ßÆµÀ×´ïÉ¢Éä½ØÃæ£¨RCS£©.²ÉÓüÆËã»úÓ²¼þÍê³ÉÕÚµ²¼ÆË㣬ͨ¹ýÎå¹âÔ´·ÖÁ½´ÎÕÕÉä»ñȡģÐͱíÃæ·¨Ê¸ÐÅÏ¢.ÔÚ¼ÆËã¾µÃæÉ¢Éäʱ£¬ÀûÓÃÁ½¸öSincº¯ÊýµÄ³Ë»ýÏû³ýÎïÀí¹âѧ¼ÆËãÖÐµÄÆæÒìµã£¬Àâ±ß±ßÔµÈÆÉäÓõÈЧµç´ÅÁ÷·¨¼ÆËã.×îÖÕ¼ÆËã½á¹ûºÍÊÔÑé½á¹ûÎǺϽϺÃ,±íÃ÷ÕâÖÖ·½·¨¹ÀËãÄ¿±êRCS¿ì½ÝÓÐЧ£¬¿ÉÒÔÓ¦ÓÃÓÚ¹¤³Ì·ÖÎö.ÔÚÄ¿±êÔìÐͶËÌí¼ÓÁËʶ±ð¶ÁÈëIGESÎļþµÄ¶Ë¿Úºó£¬½â³ýÁ˶ÔÄ£ÐÍÔìÐ͸ñʽµÄÑϸñÏÞÖÆ£¬À©´óÁËÆäÓ¦Ó÷¶Î§.

Graphical electromagnetic computing method research
based on IGES files import

Abstract: The high frequency radar cross section (RCS) of a model was computed with the graphical electromagnetic computing (GRECO) method at different wave band and polarization. The shadowed and eclipsed surfaces were identified by using the visualization hardware, and the unit normal to surfaces were got with 5 light sources  through 2 times of illumination. While computing the mirror-scattering RCS, 2 Sinc-functions were used to avoid singular points in physical optics (PO) results and method of equivalent currents (MEC) was used to compute the reflection of the edges. The agreement of the final computation results with the experimental data indicates this method could be used to estimate the model's RCS quickly and effectively at engineering analyses. Having added the interface that can identify and read initial graphics exchange specification (IGES) files, the limit to the type of the modeling files is released and the GRECO method's application range is extended.





·´ÉäÆ÷¼Ð²ãÃæ°å¾«ÃܳÉÐÎÔ­Àí

ÕªÒª:¶Ô¸ß¾«¶È¡¢´óÃæ»ý²»¿Éչ˫Çú·´ÉäÃæµÄÖÆÔìÎÊÌ⣬Ìá³öÁË»ùÓÚÀëÉ¢¶¤Ä£¡¢Õæ¿Õ¸ºÑ¹¡¢·äÎѼв㡢ӦÁ¦ÊÍ·Å¡¢»Øµ¯²¹³¥µÄ¸ß¾«¶È·´ÉäÃæ°å³ÉÐÎÔ­Àí£»½¨Á¢ÁËËıß×ÔÓÉÃæÄÚ¶àµãÔ¼ÊøµÄ±¡°å´óÄÓ¶ÈÍäÇú½â·¨¼°¼Ð²ã°å³ÉÐιý³Ì·ÂտģÐÍ£¬ÓÃÓÚÈ·¶¨³ÉÐι¤ÒÕ²ÎÊý£»ÀûÓö¯Á¦ÏÔʽºÍ¾²Á¦ÒþʽËã·¨Ïà½áºÏµÄ·½·¨ÊµÏÖ³ÉÐιý³Ì·ÂÕæ£»Í¨¹ý¿ª·ìºÍ¿ª²Û·½·¨ÊÍ·ÅÃæÄÚѹӦÁ¦£¬È·¶¨ÁËÃæ°å¿ª·ìºÍ¿ª²Û·½°¸£»Í¨¹ýÄæÏòÐÞÕýÀëɢģ°üÂçÃæ£¬Ê¹ÆäÓë³ÉÐÎÄ£ÄâµÃµ½µÄ¼Ð²ã°åÐÍÃæÎó²î×îС£¬µÃµ½Ä£¾ßÐÞÕýÒò×Ó£¬²¹³¥»Øµ¯Îó²î.ÔÚ´Ë»ù´¡ÉÏ¿ª·¢Á˼вã°å¾«ÃܳÉÐÎϵͳ.¸Ã·½·¨ÖÆÔìµÄÃæ°åÐÍÃæ¾«¶È´ïµ½25 ¦ÌmÒÔÏ£¬Òѳɹ¦µØÓ¦ÓÃÓÚ¶àÏî´óÐͽôËõ³¡ºÍºÁÃײ¨ÌìÏßµÄÖÆÔì.

Principle of precision forming for sandwich panel of
large antenna reflector

Abstract: To solve precision forming problem of the antenna panels with large non-developable double-curvature surface, the precision forming principle was proposed, based on ¡°discrete nails die, vacuum press, honeycomb sandwich, stress release in-plane, and springback compensation¡±. The problem of rectangle thin plate with free edges and constrained at arbitrary inner points with large deflection was discussed. An explicit/implicit hybrid method was used to simulate the forming process and springback to determine the processing parameters. The slotting and notching techniques were developed for releasing the compression stresses of panel in order to ensure good fit of panel on nails die. The compensation of springback has carried out by modifying discrete nails die, the adjusting coefficient of nail-head height was obtained by minimizing the shape-error between modified surface and simulation shape. The system for precision forming of antenna panels was developed and was used successfully in several actual projects of compact antenna test range and millimeter-wave antenna. The precision of reflector panel can reach below 25 ¦Ìm.
»Ø¸´´ËÂ¥

» ÊÕ¼±¾ÌûµÄÌÔÌûר¼­ÍƼö

д×÷

» ²ÂÄãϲ»¶

ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

ttpig2005

´ËÍâÈçºÎÉÏ´«¸½¼þ°¡£¬ÊÇ·ñгæÃ»ÓÐÕâ¸öȨÏÞ£º£©
2Â¥2005-12-17 14:43:09
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

goodtimeuk

Òø³æ (СÓÐÃûÆø)

1

ÊÇѽ£¬Ö»ÄÜ·¢ÕâÑùµÄÌù×ÓÁË
3Â¥2005-12-17 16:37:36
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

7654321

ÈÙÓþ°æÖ÷ (Ö°Òµ×÷¼Ò)

ÏíÊÜÉú»î

1

ÐÂÊÖ¹ÄÀø
http://muchong.com/bbs/viewthread.php?tid=97875&fpage=1
Çë°´ÕÕ°à¹æÐ޸ĺópm°æÖ÷ÖØÐÂÆÀÔÄ

½ð±ÒµÍÓÚ20ÊÇÎÞ·¨ÉÏ´«¸½¼þµÄ
Äã¿ÉÒÔ·¢µ½Òƶ¯ÓÅÅÌÉÏ
È»ºó¹«²¼Õʺŵȷ½Ê½
ÐÁ¿àÁË´ó°ë±²×Ó£¬ÖÕÓÚÔÚ±±¾©½¼ÇøÂòÁËÌ×·¿×Ó£¬½»¿îÄÇÌìÎÒÁ÷×ÅÀáÓòü¶¶µÄÊÖÌͳöÊÖ»ú×¼±¸¸æËß¼ÒÀïÈË£¬Ë­Öª¿ª»ú»­ÃæÈ´ÏÔʾ£ººÓ±±Òƶ¯»¶Ó­Äú¡­¡­
4Â¥2005-12-17 19:56:06
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

xcchen

¾èÖú¹ó±ö (ÖøÃûдÊÖ)

ľ³æ

1

²»´í£¡
·´¶Ôת¡°»ù¡±ÒòʳƷ£¡È«ÃñµÄÃâ·ÑÒ½ÁÆ¡¢Ãâ·Ñ½ÌÓý¡¢Ãâ·Ñס·¿¡¢¿É¿¿µÄÑøÀϱ£ÏÕ£¬²ÅÊÇÎÒÒªµÄ£¡
5Â¥2005-12-20 13:40:42
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
Ïà¹Ø°æ¿éÌø×ª ÎÒÒª¶©ÔÄÂ¥Ö÷ ttpig2005 µÄÖ÷Ìâ¸üÐÂ
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] Ò»Ö¾Ô¸Ìì´ó²ÄÁÏÓ뻯¹¤£¨085600£©×Ü·Ö338 +4 ²Ì´óÃÀÅ® 2026-03-13 4/200 2026-03-18 22:47 by walc
[¿¼ÑÐ] 085410È˹¤ÖÇÄÜר˶317Çóµ÷¼Á£¨0854¶¼¿ÉÒÔ£© +3 xbxudjdn 2026-03-18 3/150 2026-03-18 22:14 by zhq0425
[¿¼ÑÐ] 085600²ÄÁÏÓ뻯¹¤ +5 °²È«Éϰ¶£¡ 2026-03-16 5/250 2026-03-18 15:33 by cmz0325
[¿¼ÑÐ] 286Çóµ÷¼Á +6 lemonzzn 2026-03-16 9/450 2026-03-18 15:31 by vgtyfty
[¿¼ÑÐ] »¯Ñ§¹¤³Ì321·ÖÇóµ÷¼Á +15 ´óÃ×·¹£¡ 2026-03-15 18/900 2026-03-18 14:52 by haxia
[¿¼ÑÐ] 311Çóµ÷¼Á +6 26ÑÐ0 2026-03-15 6/300 2026-03-18 14:43 by haxia
[¿¼ÑÐ] 288Çóµ÷¼Á£¬Ò»Ö¾Ô¸»ªÄÏÀí¹¤´óѧ071005 +4 ioodiiij 2026-03-17 4/200 2026-03-18 12:36 by Linda Hu
[¿¼ÑÐ] 304Çóµ÷¼Á +12 СÐÜjoy 2026-03-14 13/650 2026-03-18 12:34 by Linda Hu
[¿¼ÑÐ] 280Çóµ÷¼Á +6 ¹¾ààÏþÏþ 2026-03-18 7/350 2026-03-18 11:25 by Î޼ʵIJÝÔ­
[¿¼ÑÐ] ²ÄÁÏÓ뻯¹¤Çóµ÷¼Á +6 Ϊѧ666 2026-03-16 6/300 2026-03-17 20:15 by peike
[¿¼ÑÐ] ²ÄÁÏר˶326Çóµ÷¼Á +6 Ä«ìÏæ¦Ý· 2026-03-15 7/350 2026-03-17 17:10 by ruiyingmiao
[¿¼ÑÐ] ±¾ÈË¿¼085602 »¯Ñ§¹¤³Ì ר˶ +16 ²»ÖªµÀ½Ðʲô£¡ 2026-03-15 18/900 2026-03-17 17:05 by ruiyingmiao
[¿¼ÑÐ] Áº³ÉΰÀÏʦ¿ÎÌâ×é»¶Ó­ÄãµÄ¼ÓÈë +8 һѼѼӴ 2026-03-14 10/500 2026-03-17 15:07 by һѼѼӴ
[»ù½ðÉêÇë] ½ñÄêµÄ¹ú»ù½ðÊÇ´ò·ÖÖÆÂ𣿠50+3 zhanghaozhu 2026-03-14 3/150 2026-03-16 17:07 by ±±¾©À³ÒðÈóÉ«
[¿¼ÑÐ] 070303 ×Ü·Ö349Çóµ÷¼Á +3 LJY9966 2026-03-15 5/250 2026-03-16 14:24 by xwxstudy
[¿¼ÑÐ] 0703 ÎïÀí»¯Ñ§µ÷¼Á +3 ÎÒ¿ÉÒÔÉϰ¶µÄ¶Ô 2026-03-13 5/250 2026-03-16 10:50 by ÎÒ¿ÉÒÔÉϰ¶µÄ¶ÔÂ
[¿¼ÑÐ] 26¿¼ÑÐÒ»Ö¾Ô¸ÖйúʯÓÍ´óѧ(»ª¶«)305·ÖÇóµ÷¼Á +3 ¼ÎÄêÐÂ³Ì 2026-03-15 3/150 2026-03-15 13:58 by ¹þ¹þ¹þ¹þºÙºÙºÙ
[¿¼ÑÐ] 294Çóµ÷¼Á +3 Zys010410@ 2026-03-13 4/200 2026-03-15 10:59 by zhq0425
[¿¼ÑÐ] 255Çóµ÷¼Á +3 Àî¼Î»Û£¬ 2026-03-12 4/200 2026-03-14 16:58 by ÓÐÖ»ÀêÅ«
[¿¼²©] ¸£ÖÝ´óѧÑî»ÆºÆ¿ÎÌâ×éÕÐÊÕ2026Äêרҵѧλ²©Ê¿Ñо¿Éú£¬2026.03.20½ØÖ¹ +3 Xiangyu_ou 2026-03-12 3/150 2026-03-13 09:36 by duanwu655
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û