Unlike high altitude aircraft, helicopters aren't so vulnerable to being seen by radar, as they fly low and are often hidden by the terrain. The big issue is the sound.
与在高空飞行的飞机不同，直升机不容易被雷达发现，因为它的飞行高度较低，且常常被地形所隐藏，因此最大的问题是噪音。
So, choose as far as possible to improve the nozzle of small high cutting speed and cutting quality is useful, but the nozzle at low altitude may cause double arc phenomenon.
所以，选用尽量小的喷嘴高度对提高切割速度和切割质量都是有益的，但是，喷嘴高度过低时可能会引起双弧现象。
In 1975, Shenyang introduced a third variant for both high - and low - to medium-altitude reconnaissance missions.
在1975年，沈阳公司推出了第三种改型用于高空和低空到中空两者侦察任务。
The riskfactors of LBW rate included multiple fetus, multiple parturition, inadequate duration of pregnancy, high altitude, low GNP and maternal anemia, et al.
本次调查低出生体重率的危险因素有多胎、多产次、孕周不足、高海拔、低国民生产总值及妇女贫血等。
The alpine grassland is distributed in high altitude and low heat environment.
高寒草地分布在高海拔、低热量生态环境；
The alpine grassland is distributed in the area with high altitude and low temperary.
祁连山高寒草地分布在高海拔、低热量的生态环境；
The phenomenon of regional synchronic contamination in North China plain is restricted by persistently steady zephyr at high altitude and various steady synoptic types at low altitude.
华北平原区域性同步污染现象受制于高空持续稳定的西风及低空各类稳定的天气型配置。
At high altitude and low temperatures, water sometimes doesn't freeze. Instead, it hovers, but as soon as something solid — like a pitot tube — flies through it, the water flash-freezes to form ice.
在高海拔和低气温的环境下，水有时并不结冰，而是处于一种不稳定的状态，一旦有像皮托管那样的固体物质从中经过，水会附着在其表面闪冻成冰。
The ripeness, the phenolic compound contents and the antioxidant activities of Cabernet Sauvignon grape berries from valley land of low altitude were higher than those of slope land of high altitude.
在黄土高原地区，低海拔谷地赤霞珠果实的成熟度、酚类化合物含量及抗氧化能力均优于高海拔坡地赤霞珠果实。
Through theory analysis and simulation, this article presents a new method of low altitude target detection and tracking, based on high distance resolution technology.
本文以高距离分辨率技术为基础，通过理论分析和仿真，寻找一种解决低空目标探测与跟踪的新途径。
This may be the low-atmosphere at high altitude effect the liver metabolism, and regulated the Thyroid Hormone by the body in order to adapt the plateau environment.
这可能是高原低气压，缺氧对肝脏代谢的影响，调节甲状腺激素，以求机体对高原坏境的适应。
A lowlander exposed to the low oxygen concentrations of high elevations can quickly fall victim to altitude sickness, whose symptoms include nausea, dizziness, and fatigue.
生活于平地的人一旦暴露在高海拔环境中，因为缺氧立即会出现高原反应：恶心，眩晕及乏力。
Objective: Explore the difference of incidence of related diseases of hypertension between people who migrated from high-altitude and who lived at low-altitude all the time.
目的：探讨高海拔移居低海拔人群与世居低海拔人群高血压相关疾病发生率的异同。
This paper mainly studies the distribution of the electron density produced by the high-altitude nuclear burst in atmosphere and gives part o the results at low-altitude.
本文主要研究高空核爆炸在大气中产生的电子密度分布，同时给出低空核爆的部分结果。
High frequency surface wave radar is an important tool of the over horizon detection of sea and low-altitude targets.
高频地波雷达是对海面、低空目标进行超视距探测的重要手段。
The utility model has simple and reasonable structure, low manufacturing cost, flexible operation, small eject lifting resistance, high ejection altitude, long flight time and long service life.
本实用新型结构简单合理、制作成本低、操作灵活、弹射升空阻力小、弹射高度高、飞行时间长、使用寿命长。
With cold starting devices, such as inlet pre-heater, optional fuel heater and coolant heater, the unit has solved the difficult starting problem under low temperature and high altitude areas.
机组装有进气预热器，可选装燃油加热器和冷却液加热器等冷启动装置，解决机组在低温、高海拔地区的发动机起动难问题。
The results indicated that foehn effect in special topography, the maintenance of warm air mass in low-altitude and the urbanization effect had strengthened high-temperature.
通过对典型高温日影响因素的分析发现：特殊地形下的焚风效应、中低空暖气团的维持以及城市化效应，均对高温强度有加剧作用。
Analysis of the observational data, the TOMS total ozone, and NCEP circulation, shows that the atmospheric ozone amount experienced a high-low-high variation with low-high-low tropopause altitude.
分析大气监测资料、TOMS臭氧总量资料和NCEP大气环流资料表明，大气臭氧总量随着对流层顶的低一高一低变化呈高一低一高的变化过程。
Analysis of the observational data, the TOMS total ozone, and NCEP circulation, shows that the atmospheric ozone amount experienced a high-low-high variation with low-high-low tropopause altitude.
分析大气监测资料、TOMS臭氧总量资料和NCEP大气环流资料表明，大气臭氧总量随着对流层顶的低一高一低变化呈高一低一高的变化过程。
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