用英文介绍乒乓球(有中文)

Posted 2023-05-10

Like many other sports, table tennis began as a mild social diversion. Descending, along with lawn tennis and badminton, was from the ancient medieval game of tennis. It was popular in England in the second half of the nineteenth century under its present name and various trade names such as Gossima and Whiff-Whaff. After the name Ping-Pong was introduced by J. Jaques & Son, the game became a fashionable craze.

和其他运动一样，乒乓球一开始只是社会中无足轻重的一部分。它跟草坪网球和羽毛球都是由网球演变而来的。在19世纪的后半叶，乒乓球就以其现在的名字或其他商业名流行于英国，比如： GOSSIMA, WHIFF-WHAFF。而当乒乓这个名字被J.Jaques&Son引进之后，乒乓球就开始越来越受欢迎。

Now, competitive table tennis is popular in Asia and Europe and has been gaining attention in the United States. The most important international competitions are the World Table Tennis Championships, the Table Tennis World Cup, the Olympics and the ITTF Pro Tour.

Continental competitions include the European Championships, Europe Top-12, the Asian Championships and the Asian Games. Chinese players have won the men's World Championships 60% of the time since 1959; in the women's competition, Chinese players have won all but three of the World Championships since 1971. Other strong teams come from East Asia and European countries, including Austria, Belarus, Germany, Japan, South Korea, Singapore and Sweden.

现在，乒乓球比赛在亚洲、欧洲都十分普遍，也开始引起美国的重视。最受重视的乒乓球比赛是世界乒乓球锦标赛、乒乓球世界杯、奥运会乒乓球赛、国际乒联职业巡回赛。

区域赛包括欧洲乒乓球锦标赛、欧洲十二强赛、亚洲乒乓球锦标赛和亚运会。自从1959年以来，中国男子乒乓球获世界冠军场次达60%。从1971年以来，中国女子乒乓球除了3次无缘世界冠军，包揽了所有的世界冠军。其他的乒乓球强国来自东亚及欧洲国家，包括奥地利，白俄罗斯、德国、日本、韩国、新加波和瑞典。

扩展资料

乒乓球在中国

新中国成立后，毛泽东主席号召“发展体育运动，增强人民体质”，乒乓球因为对场地要求不高，简便易行所以在全国开展得比较好。1959年乒乓球运动员容国团为中国夺得了第一个世界冠军，让世界瞩目。国人振奋。第26届世界乒乓球锦标赛上庄则栋和丘钟慧分别获得男女单打冠军，中国队也拿下了男子团体冠军。

从这个时候开始，中国乒乓球开始在世界上称霸，乒乓运动也长盛不衰。至2005年，共获冠军143.5枚，其中世锦赛100. 5枚，世界杯赛27枚，奥运会16枚。而且已有三次包揽世锦赛全部7个金杯，两次包揽奥运会全部4枚金牌。这样的成绩足以自傲。 

其次，乒乓球运动开展的条件不苛刻，可参与性强。男女老少都能打，天南海北都能打，室内室外都能打，有钱没钱都能打。条件好的可用高级球台打，条件差的水泥球台也能打，没有球台用几张桌子拼起来也能打。

天气好在露天可以打，遇上大风大雪在一间不大的房间里就可以打。乒乓运动又是一项全身运动，健体健脑又健心。相对于足球篮球等运动，它没有直接的身体对抗，自己可控制运动量，非常有利于普及。总之，这项运动特别适合中国的国情，得到了国人的普遍喜爱，普及程度很高

参考资料：百度百科-乒乓球

参考技术A Ping-pong
Ping-pongAthletic creation, belong to the fortuity purely.Is because of twoEnglandThe youth plays to cause of. The end of 19 centuries, a dayLondonTwo youths the person has a meal to a restaurant, at wait for the bellboy sends the rice, they feel the boredom, will pack then and at randomCigarOf a cover takes atHandPlay inside, filled the cork of the wine bottle to also stir down again at the same time, two people are on the dining table you to I to, beat to come over to beat mutually past, result, his a pair play unexpectedly into be fond of, connect to have a meal to all attend to not ascend.From here, this the game on the dining table, turn into, develop very quickly ping-pong ball game, combine to roll up London, became a ping-pong the heat at that time.In honor of contrivance country,1926, the first batch world ping-pong championships holds in London.

In former times When people play ping-pong, like mostly to stick on the wooden board racket a layer leather or cork.The rubber racket is British the thou is virtuous to invent first and use of. When a small change for, over ball in ancient virtuous match empress, on the way home arriving medicine store buying medicine, being medicine store boss will finding back throws to him, the coin falls to played to get up on the rubber plate.Ancient virtuous eye eye immediately a bright, hence direction medicine store the boss bought the rubber plate, on where own racket, reformed the oneself with meticulous care at first of racket. Afterwards, the thou is virtuous to use this piece of in this worlds a racket for gluing last rubber takes part in a game, combining to win all opponents calmly.From that time on, the rubber racket published then and publicly.

The ping-pong gets cause and others of

In exercising history, the ping-pong sport can be regarded as a young athletics exercises, it only has the history of more than 100 years, than rises the athletics(2,000 years are above) comes, it can be regarded as the reputation corresponds to reality younger generation.

In 1890, several garrisonsIndia( India) of England navy( navy) the military officer discovers by chance to play the tennis to stimulate very on an estrade for not very.Afterwards they change to replace the flexibility with the hollow and small ball solid ball not very, counteract the wooden board replaced the net claps, going forward in the table a line of this kind of is novel of" tennis match", this is the cause that table tennis get.

The Table tennis appears soon, then a kind of popular sport that become popular for a time.At the beginning of 20 centuries,The United StatesBeginning a game for producing ping-pong tools and implements.At the beginning, table tennis contain other name, such as Indoor tennis.Afterwards, a the United States manufactory creates the this new phrase in ping- pong with the voice that ping-pong send out when bumping shot, being used as the " ping-pong" patent registration trademark that he make.The Ping- pong is afterwards table tennis formal name in another.It spread to China behind, people creates the this new phrase in " ping-pong" language again.

AtJapanese, the ping-pong is called"Table tennis".The ping-pong is athletic and a lot of to use the phrase changes from the tennis of.Playing ping-pong a ball for using calls ping- pong ball or table- tennis ball, the ping-pong set calls ping- pong table, the set calls the court, the in-between ball net calls the net, propping up the shelf of the ball net call net support.

The ping-pong single game adopts generally three bureau two 胜 or five bureau three 胜 system, so-called" bureau", English is a set.The hair ball calls serve.

The ping-pong originates England.EuropeThe person call the " a last tennis" to the ping-pong up to now, from here then, the ping-pong be developped by tennis since then.The end of 19 centuries, the European widely accepted tennis exercises, but be suffered by 於 to be present a ground of with the restrict of the weather, some university students in England move to the indoors to the tennis then, regarding dining table as the ball set, the book makes the ball net, using the parchment does the racket, beating on the dining table to beat to go to.

At the beginning of 20 centuries, the ping-pong exercises in Europe withAsiaIt is booming to open the exhibition gets up.In 1926, in Germany Berlin held the international ping-pong invitational tournament.The 后 were confirmed for first batch world ping-pong championships.Established the international ping-pong the consociation the meeting at the same time.

The ping-pong is athletic extensive to open the exhibition, urging the racket to have the very big improvement with the ball.The first racket is a piece of slightly wooden board that pass through process.The 后 comes to someone to stick on the racket a layer sheepskin.With the modern industrial development in著 , the European sticks to take the rubber of the gum grain on the racket.In the beginning of 50's, the Japanese invents to stick the racket of the thick sea cotton again.First ball is a category the rubber ball,1890 of the tennis, the athlete 吉 cloth of England bring back the some conduct and actions toy from the United States ofCelluloidBall, use the 於 ping-pong sport.

In title numerously of ping-pong game, most the negative great reputation is the ping-pong championships of world, holding once annually at first,1957 the 后 changes to two years to hold once.

In 1904, an owner of stationer store in Shanghai the kingly way noon buy to return to 10 sets of ping-pongs device from Japan.From now on, the ping-pong sport streams into China.

The ping-pong sport originates England in last phase in 19 centurieses about, spreading to later on the United States, European central part, Japan, China and Korea etc. ground.The ping-pong exercises the inception was seen by the many people for amusing the activity, but the development is up to now, having become one of a world and main sports.The Olympic sports games in winning of ping-pong sport admits in 1988, becoming the event formally, among them included single, women's singles, men's doubles in man and women's doubleses.

Ping-pong technical term

A, the district of the game set

( a) the left and right half area calls again 1/2 area, its direction to hit ball with racket oneself but speech.
( two) the near net area points to be apart from the ball net 40 the rice of 厘 including of district
( three) the bottom line area points to be apart from to carry the line 30 the rice of 厘 including of district
( four) inside area is pointed to lie in near net area with the district of the bottom line area

Two, the racket bounce the form racket claps the form includes to clap the angle with clap the direction.

( a) clap the angle clap the angle is an angle to points to clap become with set.
(1) clap and set 90 for perpendicular.
(2) clap is smaller with the angle of the set formation 90 for ex- 倾 .
(3) clap is over and above with the angle of the set formation 90 for empress 仰 .
( two) clap the direction clap the direction is an angle to points the racket the or so deflecting, become with ball you line.

Three, hit ball with racket the part hit ball with racket the part is a concrete position to point to hit ball with racket racket 触 ball, it is basic up with clap the form angle to fit together mutually.

( a) upper part
( two) top central part
( three) inside upper part
( four) central part
( five) inside lower part
( six) bottom central part
( seven) lower part

Four, hit ball with racket time hit ball with racket time is that time to be pointed ball after this square set play rises to drop.

( a) run high the period:The ball playses to rise for new- risen stage from the set.
( two) period after running high:The ball plays the stage that rises nears to the apogee.
( three) apogee period:The ball plays the stage that rises attains the apogee.
( four) ex- period in descent:First stage that ball descend from the apogee beginning.
( five) descent empress period:The ball descends to near to the previous this stage in ground.

Five, hit ball with racket the route hit ball with racket the route is a line to point from hit ball with racket to order to fall the pedestal a formation.Five basic circuit( then hit ball with racket for basis)s for:The right oblique line, right straight line, left oblique line, left is straightly and inside the road the straight line.The inside road straight line ball to stand at any time in actual game an and settle of, then make track for the body ball, also call that the road of inside makes track for the body road.

Six, hit ball with racket to order to hit ball with racket to order is an opposite position for belonging to spatial position, this is to hitting ball with racket but speech of, include below three factors:The ball of ① is placed in bodily in front and back position ② ball and the high and low position of the bodily and far close quarter ③ ball.

The main military tactics of the ping-pong
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A, push to offend the military tactics

Characteristics:Main application offend the ball with versa push the speed that block with power, combine the combination falls to order the variety with rhythm variety to inhibit with transfer the other party, to fight for active or get a goal.Pushing to offend military tactics is a left pushing right strike against the method deals with the type that attackstone the main military tactics beats the method, having versa push the both sides of the ability of blocking offend the athlete and offend the 削 the combination athlete etc. to also often use it.

Method:
1, left push the right offending 2, push to block the side body to rush toward the positive hand after offending 3, push to block, the side body offends 4, left push to join together the versa offending 5, left push, versa offend, the side body rushes toward the positive hand after offending.

Announcements:
1, push, offend to all want the wired road change, fall to order the variety to change with the rhythm, this is the main method to push to offend military tactics fight for active with creates to button up intention to murder meeting.
2, push to block general regard pressing the versa hand in the other party as lord, then become suddenly positive hand, to create the aggression opportunity.If the positive hand in the other party is worse, can just push the other party positive hand for lord.
3, add suddenly in push block the dint push the other party inside road, making the other party difficult in make an effort to return to shot, then button up to kill with positive hand or side bodies.
4, the hour of opportunity to meet ball wants to be resolute to button up to kill, this is the main means to push to offend military tactics get a goal.
5, push to offend the military tactics wants to insist near set, can't defend to the death the near set again, want the near pedestal in academic association to convert with the position of the inside set, control the opponent rhythm.
6, push to offend the military tactics deal with turn of 弧 beats the method should insist near set as lord, use to push quickly with add, reduce the dint push to block the control falls to order, waiting for an opportunity near pedestal in adoption anti pull or the inside waits the power buttons up to kill the 弧 a ball, then enter positive hand continue take the offensive.

Two, the both sides offends the military tactics

Characteristics:Make use of primarily positive, versa offend the technical speed in ball to inhibit the other party with power, fight for active button up with creation intention to murder meeting.The both sides offends the technique is a main military tactics that both sides strike against the method deal with to attackstone the type beats the method.

Method:
1, offend the left buttonning up right 2, strike against two Cape, fierce button up the road of inside.

Announcements:
1, positive and versa offend the ball to all want the wired road change with fall to order the variety, for the purpose of creation button up the intention to murder the meeting.
2, want to press versa hand in the other party is lord, then attackstone the other party positive hand or the road of inside, to create to button up intention to murder meeting.
3, the hour of opportunity to meet ball wants the brave buttons up to kill.
4, the both sides offends the military tactics to under the active aggression circumstance to insist near set, passive circumstance bottom can appropriate countermarch, in near pedestal of inside or the set proceeds the countercharge.
5, the both sides offends the military tactics deals with the 弧 a ball beats the method should insist near set, use to take a 弧 for living the other party a ball quickly, wait for an opportunity near pedestal in adoption anti pull or the inside etc. power buttons up to kill the 弧 a ball, then turn in to continue the aggression.

Three, pull to offend the military tactics

Characteristics:Continuous the application is quick moving pull the creation aggression opportunity, then the adoption mounts sudden attack with button up to kill to be used as to get a goal the means.Pull to offend the military tactics to strike against quickly ball of 削 that method deal with main military tactics fight the method.

Method:
1, button up to kill after pulling 2, versa button up to kill after pulling

Main items:
1, the power that pull, button up wants the bigger 悬殊 , toing make the other party caught unprepared.
2, pull the ball want the wired road with fall to order the variety with the transfer the other party, fight for active with create opportunity to take the offensive.
3, the hour of opportunity to meet ball wants the brave buttons up to kill or mount sudden attack.
4, adopt to pull to offend the military tactics want the patience, doing not want to impatient of beg, did not want the 凶 to the opportunity ball that did not have confidence.

Four, pull, button up, hang the combinative military tactics

Characteristics:From pull to offend with put the short ball combine together but, offend quickly the method that type play the ball of 削 deal with the in common use military tactics beats the method.

Method:
1, put the short ball after pulling to offend to button up to kill or mount sudden attack tactically.
2, after pulling to offend to put the short ball in the military tactics, the combination buttons up to kill or mount sudden attack.

Main items:
1, pull to offend the inside put the short ball, wanting at the other party stands a farther and come to near net in ball hour proceed, like this, put the short ball of falling and ordering easy closing to the ball net, can increase the distance that the other party forward move with the difficulty.
2, button up to kill after putting the short ball, if the other party is been very near by pedestal, can aim at the other party body direction button up to kill, like this, can usually make the other party difficult in let return the shot.

Five, rub to offend the military tactics

Characteristics:Main application" turn, low, quick, change" of rub ball control the other party, then look for battleplane, then adopt the low 突 , hurry or pull to offend to wait the technique launches the offensive combine into consecution take the offensive;At rub the ball inside opportunity to meet ball hour the proceeding buttons up to kill, usually taking suddenly sex, can usually get a goal directly.Rubbing to offend military tactics is ping-pong every kind of an assistance whose method is all indispensable military tactics.

Method:
1, positive, versa rub the ball the combination the quick moving pull, hurry, mounting sudden attack or buttonning up kill.
2, positive, versa rub the ball the combination anti are quick moving to pull, hurry, mount sudden attack or button up to kill.

Announcements:
1, rub to offend the military tactics since want to rise early possibly plank, to fight for active, but can't have the nasty the motion of 噪 again, otherwise, rise the plank mistakes easily.
2, at rub the ball inside opportunity to meet ball hour want the brave button up to kill, this is to rubs to offend the tactical getting a goal the means primarily.
3, put in rub shortly short, can make the other party not easy to take the offensive compete first, so benefit to create aggression opportunity, in order to wait for an opportunity to use, versa hand or side bodies take the offensive.

Six, counterattack the military tactics in the 削

Characteristics:From the ball of 削 and offend ball combination but, often then force Cape added to turn the ball of 削 is lord, wait for an opportunity the countercharge;Or to turn, low, steady, the ball of 削 that change, force the opponent to pull to offend in took a stroll, with from the inside in search of opportunity, give the countercharge.This kind of military tactics has" force, change, 凶 , offend" of characteristics, is a main technique to offend, 削 join together a method.

Method:
1, positive, the versa hand 削 ball forces Cape, combinative offend or the side body offends the right side of the other party empty be.
2, positive, versa hand 削 two greatest Capeses grow the ball, joining together the positive and versa hand countercharge.

Announcements:
1, the positive and versa hand 削 ball all notices the variety that revolve the strength.Add with the 削 after 削 add turn the ball that turn the skill 削 resembles to do not turn the ball, is a valid method to make the other party pull up the high ball, to proceed to counterattack.
2, the hour of 削 ball wants to press the low curve possibly, toing avoid the other party button up to kill or mount sudden attack.
3, the ball of 削 forces the hour of Cape want the adequacy to match with the 削 the other corner, toing make the other party to hit ball with racket in took a stroll.

Seven, the hair ball attacks and occupy the military tactics

Characteristics:The hair ball attacks and occupy the military tactics to revolve, circuit, fall to order and the flat-out and different hair ball return to shot to the other party that increase the difficulty, making its emergence opportunity ball, or lower to return to ball quantity, then take the offensive compete first, toing fight for active or get a goal directly, this is the main military tactics that ping-pong is all a method takes the offensive especially the type beats the method with get a goal the means.

Method:
1, send down to revolve with" do not turn" attack and occupy.
2, the hair is positive and versa to rush the ball attacks and occupy.
3, positive and versa hand in hair side top, bottom the 旋 ball attacks and occupy.
乒乓球
乒乓球运动的产生，纯属偶然。是因两个英国青年玩耍引起的。 19世纪末，一天伦敦两个青年人到一家饭馆去吃饭，在等待侍者送饭时，他们感到无聊，便信手将装雪茄的盒盖拿在手中玩，同时又将酒瓶上的软木塞也拨了下来，两人在餐桌上你来我往，相互打过来打过去，结果，他俩玩得竟入了迷，连吃饭都顾不上了。由此，这项餐桌上的游戏，很快就演变、发展成乒乓球赛，并席卷伦敦，一时形成了一股乒乓球热。 为了纪念发明国，1926年，第一届世界乒乓球锦标赛在伦敦举行。

早先人们打乒乓球时，大都喜欢在木板球拍上贴一层皮革或软木。胶皮球拍是英国人古德首先发明并使用的。 一天，古德赛完球后，在回家途中到药店买药，当药店老板将找回的零钱扔给他时，钱币落在胶皮盘子上弹了起来。古德的眼眼顿时一亮，于是向药店老板买下了胶皮盘子，安在自己的球拍上，精心改革了自己原先的球拍。 后来，古德用这块世上第一个粘上胶皮的球拍参赛，并从容地战胜了所有的对手。自此，胶皮球拍便公开问世了。

乒乓球得名的由来及其它

在运动史上，乒乓球运动可以算是一项年轻的体育运动，它只有100多年的历史，比起田径运动（两千年以上）来，它可算是名副其实的后辈。

1890本回答被提问者采纳

赛事解析｜乒乓球时序动作定位大赛亚军方案分享

比赛介绍

时序动作定位(提案生成)是计算机视觉和视频分析领域一个具有挑战性的任务。本次比赛不同于以往的ActivityNet-TAL，FineAction等视频时序检测动作定位比赛，采用了更精细的动作数据集–乒乓球转播画面，该数据集具有动作时间跨度短、分布密集等特点，给传统模型精确定位细粒度动作带来了很大挑战。

数据集介绍及处理

数据集介绍

本次比赛的数据集包含了19-21赛季兵乓球国际比赛（世界杯、世锦赛、亚锦赛，奥运会）和国内比赛（全运会，乒超联赛）中标准单机位高清转播画面的特征信息，共包含912条视频特征文件，每个视频时长在0～6分钟不等，特征维度为2048，以pkl格式保存。

数据处理方案

1.数据预处理

本赛题数据集中每条视频特征有不同的帧长（训练集帧长范围为464~8992，其中90%的序列帧长超过8704），对于如此长且长度不统一的视频序列，将其直接输入到模型中用于训练是不现实的。我们对最初的训练集按39:1的比例进行划分，得到新的训练集与验证集。当然，可以按照其他比例如9:1进行数据集划分，但是因为我们设计的验证方案（后续会提到）在数据量较多时耗费的时间更长，因此在验证可靠性与验证时间之间做出了取舍。

训练集 

参照BMN[1]论文单元3.5中Training Data Construction部分所讲，我们也以一个滑动窗口对每一个长视频序列进行切分，其中步长为窗口长度的一半，同时要注意的是我们所保留的每一个视频切片必须包含至少一个完整提案。但是滑动窗口的长度如何选取呢？

首先我们对训练集相应的动作提案标签进行分析，总共有19054个提案标签（长度范围为1~831），分布如图1所示。我们设提案长度为D，当D=93时，已能够覆盖99.9%的动作提案。因此我们选择提案长度D为100，足以覆盖几乎全部的动作提案。当然为了减少训练推理时计算量，也可以选择更小的D，如D=50。正如冠军团队所说，PaddleVideo的anet_pipeline.py第50行出现错误，使得视频切片长度T与提案长度D不相等时便报错，故我们默认滑动窗口长度T与D相等，皆为100。当然，当T稍微更大时，比如T=200，可以使模型更好地建模长提案的上下文，但会带来更多的计算代价，因此T大小的选择可以在速度与性能之间进行权衡。

图1 训练集动作提案长度分布

验证集 

为了在训练完模型之后对保存的模型进行筛选得到其中较好的模型，我们先后设计了两种验证方案。第一种方案是将验证集按照训练集的视频切分方式，即最后保留的切片都包含至少一个完整提案。这其实是与测试时不符的，即我们不应该事先知道哪些切片包含提案，而是应该对所有切片一视同仁。因此，第一种方案的验证分数远超A榜测试分数，但并不推荐。第二种方案则是模拟测试过程，即将验证集按照训练集的视频切分方式，但最后保留所有切片（每个切片不一定包含提案）。模型预测之后将每个视频对应的所有切片预测的提案进行汇总并进一步使用soft nms等方法筛选之后作为原未划分视频的预测提案信息，与标签对比计算AUC分数，作为模型筛选的凭证。

因此，我们对测试数据集的处理与验证集的第二种验证方案一致，即以一个滑动窗口对每一个长视频序列进行切分，其中步长为窗口长度T的一半，保留所有的切片。

2.提案后处理

如验证集第二种验证方案所讲，在选定的模型对测试集所有视频切片预测之后，我们将每个视频对应的所有切片预测的提案进行汇总并进一步使用soft nms等方法筛选之后作为原未划分视频的预测提案信息，并保存在submission.json中，打包之后即可提交A榜或B榜。

模型设计思路

这里围绕我们的最终模型进行讲述，思路演进可以见[2]。

模型整体架构

首先要提及的是我们的基础网络，即百度自研的BMN[1]模型，如图2所示。

图2 BMN模型整体架构

该模型由三个模块组成，基础模块（Base Module）作为主干网络处理输入的特征序列，TEM模块（Temporal Evaluation Module）预测每一个时序位置属于动作开始、动作结束的概率，PEM模块(Proposal Evaluation Module)生成BM置信度图。基于BMN[1]模型，我们对Base Module部分进行了修改，但继续沿用TEM模块和PEM模块，如图3所示。

图3 （a）我们最终模型的Base Module；

图3 （b）我们最终模型的整体结构

Base Module

为了使模型轻量，BMN[1]的基础模块使用的是两层的3x3分组卷积。由于分组之后，每通道信息只在各组中融合，而组与组之间无信息流通，会使得模型丢失一部分信息，降低模型容量。轻量化网络ShuffleNet采用Channel Shuffle操作使得信息跨组流通来解决这个问题，同样地，在这里我们也引入了Channel Shuffle操作。当然，也可以使用1x1卷积来解决，但会引入额外的参数和计算量。Channel Shuffle操作的代码如下：

为了扩大时域建模的感受野和建模更多的上下文信息，同时保证模型轻量，我们采用stride=2的3x3分组卷积对输入特征进行下采样。由于U-Net网络在图片分割领域的成功，正如BSN++[3]中所述，采用U-Net这种Encoder-Decoder结构，网络可以同时捕捉高层次的全局上下文和低层次的局部细节。这恰恰可以帮助模型对提案边界的预测和对预测提案置信度的评估。但是与BSN++[3]不同，我们将U-Net结构应用到了基础模块，且采用的不是U-Net++[5]。由图3（a）可以看到我们的基础模块的结构，在使用U-Net结构之前，由于输入特征序列的维度为2048，为了减少计算量，我们先利用两层卷积对输入特征序列进行降维，将降维后的输出输入到Encoder-Decoder结构中。为了尽可能地不引入过多的参数量和计算量，我们采取分组卷积和Channel Shuffle操作，且尽可能地使用较少的通道数，同时U-Net结构仅采用了5层。当然，也引入了额外的跳过连接，来使得U-Net结构的输入输出特征融合。

从骨骼点动作识别方法SGN[6]显式使用节点类型和帧索引来增强模型对节点语义信息的建模得到启发，我们引入时域位置编码，显式地将视频帧顺序加入到模型中，确定视频开始与结束的差异，增强模型对一帧的表达能力和对全局、局部上下文的建模能力，更好地确定动作提案的开始与结束边界。当然，位置编码的加入位置是有多种选择的。我们经过比较AUC分数与引入的代价，最终确定将其加入到降维模块与U-Net结构之间。当然当我们在TEM模块之前加入位置编码时，可以将视频序列时间正向、反向两次传入模型的TEM模块，利用类似集成的方式来提高提案开始点和结束点的预测精度，但考虑到两次可能增加一部分计算量，没有采用。不过仅仅引入时域位置编码就大大地提高了模型的预测性能，使得我们的A榜分数从48.216提升至48.828。

当然，在Base Module中也可以引入注意力机制，但测试发现SE模块没有带来性能提升，且引入了额外的计算量。

Temporal Evaluation Module

与BMN[1]模型一致，我们沿用了它的TEM模块结构，仅在第一个卷积的输入通道数有差别。当然，修改过的SE模块、non-local块等注意力机制也曾应用到两层卷积之间，但提升不大，且引入了额外的计算量，故最终方案没有采用。

SE模块代码如下：

Proposal Evaluation Module

PEM模块是BMN[1]模型推理时间占比最大的部分，从图[2]可以看到，PEM模块存在3D卷积和多个2D卷积，带来了巨大的计算耗费。当然我们最终方案沿用的是BMN[1]模型的PEM模块。这里只提及我们做过的一些尝试。首先，如何对3D卷积进行取代？可以采用（2D+1D）来取代3D卷积；也可以减小3D卷积的输出通道数，采用2D卷积与3D卷积两路混合来取代3D卷积；采用3D可分离卷积或分组卷积等。虽然产生了高效的模型，但不可避免地带来了性能下降，不过A榜AUC分数仍能达到48分以上。然后，对2D卷积进行处理，我们尝试2D分组卷积和Channel Shuffle操作来替代，引入U-Net结构等，但相对最终方案性能都略低，但相对高效。

总结与完善方向

由于比赛要求不超过两个模型，且提到除了模型精度以外模型数量和模型耗时指标的权重分数会高于其他指标，我们专注于模型本身的设计，在兼顾轻量的同时追求高性能，故TTA等集成方法均没有采用。由于是基于A榜分数改进模型，最终模型不可避免地对A榜测试集过拟合，使得B榜分数下降，因此提高模型泛化性也是未来要改进的一个方向。此外，模型压缩等手段我们均未采用，所以设计容量大但冗余的模型，再进行压缩得到轻量结构也是一个完善方向。当然，模型本身也有许多完善的方向，比如PEM模块的轻量化。参照冠军方案[7]，训练数据处理与增强方案也可以进一步完善。

最后感谢百度官方提供算力与框架支持，感谢PaddleVideo套件提供强力支持。最后希望PaddleVideo可以把更多前沿的学术成果迁移到飞桨框架，越做越好！

参赛项目地址：

https://aistudio.baidu.com/aistudio/projectdetail/3548768

PaddleVideo地址：

https://github.com/PaddlePaddle/PaddleVideo

参考文献

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[3] Haisheng Su, Weihao Gan, Wei Wu, Yu Qiao, and Junjie Yan. BSN++: Complementary Boundary Regressor with Scale-Balanced Relation Modeling for Temporal Action Proposal Generation[C]. In Proceedings of the AAAI Conference on Artificial Intelligence. 2021, 35(3): 2602-2610.

[4] Ronneberger O, Fischer P, and Brox T. U-Net: Convolutional Networks for Biomedical Image Segmentation. In International Conference on Medical image computing and computer-assisted intervention. Springer, Cham, 2015: 234-241.

[5] Zongwei Zhou, Md Mahfuzur Rahman Siddiquee, Nima Tajbakhsh, and Jianming Liang. UNet++: A Nested U-Net Architecture for Medical Image Segmentation[M]. Deep learning in medical image analysis and multimodal learning for clinical decision support. Springer, Cham, 2018: 3-11.

[6] Pengfei Zhang, Cuiling Lan, Wenjun Zeng, Junliang Xing, Jianru Xue, and Nanning Zheng. Semantics-Guided Neural Networks for Efficient Skeleton-Based Human Action Recognition[C]. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition. 2020: 1112-1121.

[7] 来路生云烟，路里老咯，基于飞桨实现乒乓球时序动作定位大赛 ：B榜第1名方案.