PWS

引用部分微軟的話就是：

“...在企業 Intranet 上，Personal Web Server 可用於以自身的格式快速共享文檔，或者將文檔轉換為 HTML，然後使用 PWS 在不同的操作系統共享這些文檔。”

“由於 Personal Web Server 支持 Active Server Pages，因此可以作為 Web 站點的開發和測試平台。在企業伺服器上或 Internet 服務提供商處使用您的站點前，可以先在辦公室或家裡創建站點，並使用 Personal Web Server 進行測試。

普達-威利綜合症英文全稱為Prader-Willi syndrome，為一種罕見疾病，與基因組印跡相關、以肥胖和生長發育遲緩為主要臨床特徵的遺傳性疾病。目前證實為15號染色體缺失所致，屬於遺傳疾病致範疇。

患者表現為飢餓，且不能因進食而消除飢餓感，致使患者暴飲暴食。有時患者會出現吃貓糧狗糧，甚至煤等不是食物的物品進行“充饑”。由於長期的暴飲暴食患者表現為病態肥胖。同時患者可伴有智力低下及其它異常。

該病尚無藥物治療，只能通過控制飲食，加強鍛煉來對抗疾病。抑制食慾的藥物對該病無效。若不能有力的控制食慾，患者常因體重超標而引起的各種疾病而英年早逝。

PWS：風切變預警系統

英文全稱為Predictive Windshear System ( PWS)

現在飛機的氣象雷達大多都加裝了PWS預測風切變功能。飛機的GPWS近地警告系統也提供低空風切變警告。判斷原理是多普勒頻移原理。飛機頂風產生正的多普勒頻移，順風產生負的多普勒頻移，如果在一個很短的距離內探測到明顯的正負風速變化，則可判斷為風切變。機組得到風切變警告后需立即採取措施，比如停止近進，復飛，風切變機動飛行，來躲開風切變。起飛和復飛時，飛機的自動駕駛系統會提供飛行指引，幫助機組進行正確的俯仰操作。進近時，如果遭遇嚴重風切變，機組應該脫開自動駕駛，進行人工飛行，否則有可能失速。不操縱飛機的駕駛員要密切監視垂速表和高度表，機組的快速反應和清醒的意識是非常重要的。

Windshear is a sudden, rapid change in wind velocity or direction. It is often found in –– but is not limited to –– thunderstorms or other highly unstable atmospheric events.

The most dangerous form of windshear is known as microburst, a vertical column of air rapidly descending toward the ground.

Upon reaching the ground, microburst spreads out horizontally, creating a horizontal outflow.

Entering a microburst is very dangerous for an airplane because the wind may be strong enough to overcome the maximum of climb performance.

Known as the Predictive Windshear System ( PWS), this technology permits weather radar systems to scan the atmosphere ahead of an airplane and detect windshear before the airplane enters it.

Predictive Windshear System ( PWS)

The Principle of PWS

PWS uses wind velocity data gathered by a Doppler weather radar system to identify the existence of a windshear.

Radar energy is emitted through the airplane's radome in order to gather atmospheric information such as wind speed and direction. The weather radar receiver/transmitter then uses this information, in addition to air data and inertial data, to determine the presence of a windshear.

The weather radar processor identifies wind velocity characteristic that indicate a rapid change in wind velocity or direction over a relatively small area. When the magnitude of the detected windshear reaches a predetermined intensity level, the system alerts the flight crew.

If the PWS detects a windshear from a significant distance, the flight crew may be able to avoid it completely. If windshear is unavoidable, however, PWS gives the flight crew valuable time to increase speed or altitude before the airplane enters a windshear.

The Principle of PWS

PWS provides windshear detection with very few operational changes that will affect flight crews.

First, the flight crew does not need to manually turn on the weather radar for it to operate in the windshear mode.

If not already turned on by the flight crew, the radar automatically turns on at 2,300 feet (700m) above ground level (AGL) for approach and landing coverage.

The radar also turns on automatically before takeoff—using air-ground and takeoff thrust logic—to provide windshear coverage during takeoff roll, rotation, and climbout.

The flight crew can manually activate PWS on the ground by turning on the weather radar. The automatic activation of PWS does not affect the weather radar display; it will remain in the mode and range selected by the flight crew.

The Principle of PWS

The PWS automatically sets weather radar gain and tilt when in a windshear mode. As a result, it is effective regardless of the settings made by the flight crew on the weather radar control panel.

Crew-selected tilt and gain are used when the radar is in a weather sweep. PWS requires a dedicated sweep of the weather radar to detect windshear.

If the flight crew uses the weather radar below 2,300 feet (700m) AGL, the radome will alternate between normal weather radar sweeps and PWS sweeps.

The Principle of PWS

Figure 11.1

Weather Radar Control Panel

The Principle of PWS

Predictive Windshear System has an effective range of three nautical miles ahead of the airplane.

At typical approach speeds of Boeing airplanes, the radar gives a detected windshear alert from 10 to 70 seconds before windshear entry.

The level of alert given to the flight crew depends on the position of the detected windshear threat relative to the airplane.

PWS：power system/ power subsystem 電源系統/ 電源適配器

在計算機，尤其是計算機硬體中，PWS與ADA (Adapter)一樣，指代電源適配器。