Dragonflies’ Wings Have a Novel Shape

Dragonflies flit about freely in the open sky, equally comfortable on a gentle breeze or a strong wind. This is actually quite an amazing feat! The air is a very viscous medium for a dragonfly, whose body mass is a mere 1-2g. To put this in perspective, imagine a human being trying to fly underwater. How then is a dragonfly able to glide around so smoothly? The secret lies in the shape of its wings. Unlike the streamlined cross-section of a hawk wing or an airplane wing, a cross-section of a dragonfly wing reveals uneven ridges. When the dragonfly is in flight, these ridges create small vortices of air that smoothly stream external air towards the back of the wings, generating lift even in light breezes. In stronger winds, the vortices counteract turbulence in the air flowing around the wings, allowing the dragonfly to remain steady as it hovers.

Transfer/Dispose/Circulate:: Convection、Flight

Energy creation

The Nippon Bunri University Microfluid Engineering Laboratory has carried out successful flight experiments with Mars Flyer, a miniature robot (palm-sized and weighs just 4g) that flies without flapping wings, and Dragon Flyer (also palm-sized and weighs 25g).

Dragon Flyer.

Small flying objects modeled after dragonflies can maintain flight stability at extremely low speeds. One anticipated application is the development of miniature, remote-controlled “robot insects” equipped with cameras to aid in rescue missions in disaster areas. The uneven wing structure, capable of capturing air even in a light breeze, could be borrowed in the development of micro wind turbines. The large wind turbines currently in production are costly to build, and concerns have been raised regarding the high frequency waves created by the high-speed blade rotation and their impact on the environment and human residents. A micro wind turbine constantly spinning away inside a home or under the eaves may be the solution to such problems.

Query	Affected	Num. rows	Took (ms)	Actions
SHOW FULL COLUMNS FROM `contents`	16	16	3	maybe slow
SELECT CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.COLLATIONS WHERE COLLATION_NAME= 'utf8_general_ci';	1	1	1
SHOW FULL COLUMNS FROM `users`	10	10	2	maybe slow
SHOW FULL COLUMNS FROM `groups`	4	4	2	maybe slow
SHOW FULL COLUMNS FROM `permissions`	5	5	2	maybe slow
SHOW FULL COLUMNS FROM `groups_permissions`	3	3	2	maybe slow
SHOW FULL COLUMNS FROM `groups_users`	3	3	9	maybe slow
SHOW FULL COLUMNS FROM `contents_searches`	6	6	2	maybe slow
SHOW FULL COLUMNS FROM `attachments`	11	11	2	maybe slow
SHOW FULL COLUMNS FROM `attachments_revs`	13	13	3	maybe slow
SHOW FULL COLUMNS FROM `contents_related_items`	5	5	2	maybe slow
SHOW FULL COLUMNS FROM `related_items`	6	6	2	maybe slow
SHOW FULL COLUMNS FROM `contents_related_items_revs`	8	8	2	maybe slow
SHOW FULL COLUMNS FROM `contents_tags`	5	5	10	maybe slow
SHOW FULL COLUMNS FROM `tags`	7	7	2	maybe slow
SHOW FULL COLUMNS FROM `tag_groups`	6	6	4	maybe slow
SHOW FULL COLUMNS FROM `contents_tags_revs`	7	7	2	maybe slow
SHOW FULL COLUMNS FROM `contents_revs`	18	18	16	maybe slow
SELECT `Content`.`id`, `Content`.`user_id`, `Content`.`last_edit_user_id`, `Content`.`post_date`, `Content`.`post_date_year`, `Content`.`post_date_month`, `Content`.`post_date_day`, `Content`.`title`, `Content`.`title_en`, `Content`.`content`, `Content`.`plain_content`, `Content`.`page_view`, `Content`.`flag`, `Content`.`mod_count`, `Content`.`created`, `Content`.`modified` FROM `contents` AS `Content` WHERE `id` = 175 LIMIT 1	1	1	0
SELECT `Attachment`.`file_name`, `Attachment`.`dir`, `Attachment`.`model`, `Attachment`.`foreign_key` FROM `attachments` AS `Attachment` WHERE `file_name` <> 'default.jpg' AND `Attachment`.`foreign_key` = (175)	2	2	0
SELECT `ContentsRelatedItem`.`content`, `ContentsRelatedItem`.`related_item_id`, `ContentsRelatedItem`.`content_id` FROM `contents_related_items` AS `ContentsRelatedItem` WHERE `ContentsRelatedItem`.`content_id` = (175)	11	11	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 1	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 2	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 4	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 6	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 7	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 8	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 9	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 9	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 9	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 11	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 12	1	1	0
SELECT `ContentsTag`.`id`, `ContentsTag`.`tag_group_id`, `ContentsTag`.`mod_count`, `ContentsTag`.`tag_id`, `ContentsTag`.`content_id` FROM `contents_tags` AS `ContentsTag` WHERE `ContentsTag`.`content_id` = (175)	3	3	0
SELECT `Tag`.`name`, `Tag`.`comment`, `Tag`.`tag_group_id` FROM `tags` AS `Tag` WHERE `Tag`.`id` = 37	1	1	0
SELECT `TagGroup`.`code`, `TagGroup`.`name` FROM `tag_groups` AS `TagGroup` WHERE `TagGroup`.`id` = 3	1	1	0
SELECT `Tag`.`name`, `Tag`.`comment`, `Tag`.`tag_group_id` FROM `tags` AS `Tag` WHERE `Tag`.`id` = 40	1	1	0
SELECT `TagGroup`.`code`, `TagGroup`.`name` FROM `tag_groups` AS `TagGroup` WHERE `TagGroup`.`id` = 3	1	1	0
SELECT `Tag`.`name`, `Tag`.`comment`, `Tag`.`tag_group_id` FROM `tags` AS `Tag` WHERE `Tag`.`id` = 104	1	1	0
SELECT `TagGroup`.`code`, `TagGroup`.`name` FROM `tag_groups` AS `TagGroup` WHERE `TagGroup`.`id` = 7	1	1	0
SELECT `RelatedItem`.`id`, `RelatedItem`.`code`, `RelatedItem`.`name`, `RelatedItem`.`created`, `RelatedItem`.`modified`, `RelatedItem`.`flag` FROM `related_items` AS `RelatedItem` WHERE `code` = 'function' LIMIT 1	1	1	0
SELECT `Content`.`id`, `Content`.`title`, `Content`.`title_en` FROM `contents` AS `Content` WHERE id = (NULL) ORDER BY `id` desc	0	0	0

Message	Memory use
Component intitailization	6.79 MB
Controller action start	6.83 MB
Controller render start	6.90 MB
View render complete	7.93 MB

Message	Time in ms	Graph
Core Processing (Derived)	445.11
Component initialization and startup	85.56
Controller action	58.27
Render Controller Action	69.85
» Rendering View	64.57
» » Rendering APP/views/contents/view.ctp	33.48
» » Rendering APP/views/layouts/default.ctp	20.84
» » » Rendering APP/views/elements/header.ctp	1.59
» » » Rendering APP/views/elements/content_sidebar.ctp	0.45
» » » Rendering APP/views/elements/footer.ctp	0.72

Dragonflies’ Wings Have a Novel Shape

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Dragonflies’ Wings Have a Novel Shape

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