uncertainty,不确定度

uncertainty of measurement,测量不确定度

uncorrected result,未修正结果

uncoupled modes,非耦合振型

undampted natural frequency,无阻尼固有频率

undamped natural mode of vibration,无阻尼固有振动模态

under water acoustic measurment,水声综合测量仪

underdamping,周期阻尼；欠阻尼

undersea buoy system,水下浮标系统

understandability,可理解性

underwater absorption meter,水下吸收仪

underwater acoustic,水（下）声学

underwater acoustic communication set,水下通讯装置

underwater acoustic measurement,水声测量

underwater acoustic transducer,水声换能器

underwater camera,水下照相机

underwater communication system,水下通讯装置

underwater holography,水下全息摄影

underwater irradiance meter,水下辐照度计

underwater lighting system,水下照明装置

underwater movie camera,水下电影摄影机

underwater panoramic camera,水下全景照相机

underwater polarimeter,水下偏振仪

underwater radiance meter,水下辐射率计

underwater scattering meter,水下散射仪

underwater sound,水（下）声学

underwater sound integrated measuring set,水声综合测量仪器

underwater sound test tank,水声试验水池

underwater television camera,水下电视摄像机

underwater towed system,水下拖曳系统

underwater towed vehicle,水下拖曳体

underwater transducer array,水声换能器基阵

underwater transmissometer,水下透射率仪

underwater vehicle,水下运载工具

underwater visibility,水下能见度

underwater window,水下“窗口”

undetermined components,非测组分

unearthed voltage transformer,不接地型电压互感器

uniaxial strain gauge,单轴应变计

uniform stability,一致稳定性

uniform temperature zone,均温区

uniform temperature zone length,均热带长度

uniformity of table motion,台面运动的均匀度

union nut,双端螺母

unit,单元；单位

unit(of measurement),（测量）单位

unit area acoustic impedance,声阻抗率

unit feedback,单位反馈

unit resolution,单位分辨

unit resolution mass,单位分辨质量

unit step function,单位阶跃函数

universal balancing machine,通用平衡机

universal gas chromatograph,通用气相色谱仪

universal head loss coefficient,通用压头损失系数

universal testing machine,万能试验机

universal toolmaker's microscope,万能工具显微镜

unmanned submersible,无人潜水器

unsaturated standard cell,不饱和式标准电池

unsteady flow,不稳定流

upper-air observation,高空观测

upper limit of the nominal of use for frequency,标称使用频率范围上限

upward (total) radiation,向上（全）辐射

upward terrestrial radiation,向上地球辐射

urea enzyme transducer [sensor],酶（式）尿毒传感器

urinary bladder inner pressure transducer [sensor],膀胱内压传感器

usable cross-section of the test channel,试验流道的可用横截面

usable minimum immersion depth,最小可用浸入深度

useful life,使用寿命

useful spectral range,有效光谱范围

user adjustment,用户调整

user layer,用户层

utility routine,服务程序；实用程序；实用例行程序

utility software,实用软件

UV dosimeter,紫外线表

UVW anemometer,三维风速表；UVW风速表

vacancy chromatography,空穴色谱法

vacuum,真空；负压

vacuum accumulator,真空贮气筒

vacuum correction,真空修正

vacuum drying chamber,真空干燥箱

vacuum evaporator,真空镀膜台

vacuum fusion gas chromatography,真空熔融气相色谱法

vacuum gauge,真空表；真空规管

vacuum system,真空系统

vacuum transducer [sensor],真空[负压]传感器

vacuum valve,真空阀门

validity check,有效性检验

validity event,有效事件

valley,谷

Vallot helio-thermometer,瓦劳特日光温度表

value analysis,价值分析

value engineering,价值工程

value (of a quantity),（量）值

value of image shift,图象漂移量

value of scale division,标度分格值

value of scale mark,标度值

values transfer,量值传递

valve,阀