The sun shines brightly and light twinkles on the surface of the swimming pool. Everything looks peaceful and quite. Suddenly, the calm is broken by the sound of people flapping and splashing water. Despite the March cold, even the weather does not prevent people from swimming.

“People in Shantou like swimming very much,” said Yang Qingwei, who is in charge of the operation of Zhongshan Park, where there is also a swimming pool. “More than 1,000 people came to our swimming pool in a day in summer.”

As there are so many people, the quality of the water has become a topic of public concern.“We adopt the cycle of water purification devices, which works about 15 hours every day in summer, and six hours every two days in winter,” said Zeng Yonghua, 35, the manager of the swimming pool in Zhongshan Park. “We usually change the entire water once a year.”

There are 80 swimming pools in total in Shantou among the hotels, schools and residential areas, according to Zhang Biaoming, the Chief of Policies and Regulations of Sports Board.

The swimming pool in Zhongshan Park is one of the most famous swimming pools in Shantou. “Most of our customers are families, they train their children to learn swimming here,” Yang said.

There are two inlets and five outlets in the swimming pool in Zhongshan Park, and the latter is much bigger than the former. All the water entering into the pool has already been disinfected with Sodium Hypochlorite, which can protect people from the E. coli, a kind of bacterium which is harmful to the body when its content is more than 0.3mg per liter to 0.5 mg per liter.

Zeng emphasized that Sodium Hypochlorite should be liquid rather than powder, as liquid can more easily evaporate. Every time they have to get a certificate of quality from the Health Inspection and Supervision Centre, in order to buy the chemicals from the factory.

The swimming pool managers have an official record book from the quarantine station to keep track of the amounts of chemical agents poured into the pool.

“When the officials from the Health Inspection and Supervision Centre came, we showed the tally book to them,” Zeng said. “The inspectors often take a liter of water from the pool and add a special pill into it. And then the water becomes  colored. They compare the color to the standard color on a kind of special test paper.”

“We only are in charge of public swimming pools and go there irregularly. But we haven’t found any that have problems with the water,” said Zhang, the person in charge of inspecting pools.

The cycle of water purification devices functions well, but is also expensive. “It will take about 600 RMB if it works for ten hours continuously, and each time it will lose 10% of water during the process of backwashing and sewage disposal,” Zeng added.

The most advanced sterilization technology, however, is the ozone-activated carbon sterilization technology which combines the adsorption of activated carbon with the oxidization of Ozone. It is considered the most environment-friendly because it produces no secondary pollutants. This is the technology that was used in the National Aquatics Center during the Beijing Olympic Games.

However, because of its high equipment cost and large power consumption, it has only been used in the international competition swimming pool or a number of high-grade water parks. Even as the only national diving training base in Shantou, the swimming pool on the Haibin Road around the People’s Square still uses Sodium Hypochlorite for disinfection.

“But the water here is blue while it’s green in most of ordinary swimming pools, as we used Copper Sulfate to limit the growth of phytoplankton,” said Ma Liguang, the leader of Shantou Diving Team.

Apart from this, another kind of advanced equipment plays an important role in the water purification in the diving pool. It’s called preparatory pool which has a corresponding water level with the diving pool. When the latter doesn’t have enough water, the former will flow into it automatically. “In this way, we don’t have to empty the pool to infuse new water,” Ma said.

Inflatable armbands
    Inflatable armbands (usually referred to as just "armbands"), are a device to help a wearer float in water and learn to swim.
    Inflatable armbands are typically cylindrical inflatable plastic bands that are inflated and worn on the upper arm. When the wearer is in water, the air inside the armbands provides buoyancy on account of its far lower density than the water. Although often thought of as a child's flotation device, armbands are also available in adult sizes.

Spartan Scout
    The Spartan Scout is a crewless surface watercraft, also known as an unmanned surface vehicle (USV) developed by the United States in 2001 and first demonstrated in late 2003. The craft, a rigid hull inflatable boat, weighs two tons, and is seven meters (23 ft) in length. It has a .50 caliber machine gun, as well as various sensors such as electro-optical and infrared surveillance and surface search radar. The Spartan is capable of carrying a 3,000 lb payload. According to a press release from the US Navy, the Spartan Scout will also come in an 11-meter version, capable of carrying a 5,000 lb payload.
    Although a two-man boat crew is needed to deploy the Spartan Scout, once deployed it is capable of working autonomously or semi-autonomously. During its demonstration deployment, the Spartan Scout was configured for surface surveillance and force protection, although it can potentially be configured for more complex missions.

Flowerpot Island
    Flowerpot Island is an island in Georgian Bay, and is a part of the Fathom Five National Marine Park of Ontario, Canada. The island spans 2.1 km from east to west, and 1.5 km from north to south, and has a total area of 2 km² (500 acres). It has 6 km of trails on it, and is located 6.5 km north-east of Tobermory. It is accessible by cruises and rigid inflatable boats from Tobermory.
    Its name comes from two rock pillars (originally three, one collapsing in 1903) on its eastern shore, which looks like flowerpots.

Hypercone (spacecraft)
    A hypercone is a mechanism for atmospheric reentry deceleration proposed for use by future Mars landing missions. It is an inflatable structure combining characteristics of both heat shields and parachutes.
The hypercone is intended to supplement other deceleration mechanisms, bridging a gap in capability between conventional heat shields (which are useful for taking a spacecraft from orbital velocity down to several times the speed of sound) and conventional parachutes or landing rockets (which are only useful below the speed of sound). Mars' combination of thin atmospheric density and relatively large gravity makes it impossible for a conventional heat shield to break landing capsules of more than a few tons' mass to subsonic velocity before they would impact the surface.
    A hypercone consists of a large donut-shaped balloon that supports a cone-shaped sheet of heat-resistant fabric thirty to forty meters in diameter, with the capsule located at the point of the cone. The balloon is rapidly inflated to expand the cone to full size and the resulting drag slows the capsule to a velocity where other landing mechanisms can finish the job of bringing it to a soft landing.

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