Topics

  • U
  • Ultrafine particles (UFP)
    According to the most common definitions, ultrafine particles (UFP) or ultrafine dust refer to airborne particles with a diameter of between 1 and 100 nanometres (nm) (DIN 2006; ISO 2007; VDI 2009; EPA 2004). UFPs…
  • Underground installations
    Pursuant to Section 2(15) of the Ordinance on Facilities for Handling Substances Hazardous to Water (AwSV), these are installations of which at least one part  is completely or partially embedded in the ground;…
  • Unquestionably pleasant smell from a hedonistic point of view
    In accordance with Annex 7 of the TA Luft, an odour emitted by an installation is classified as unambiguously pleasant if it is demonstrated, using the polarity profile method, that the odour from the installation…
  • Upper explosive limit (UEL)
    The upper explosive limit (UEL) is the highest concentration of a flammable gas or vapour in the air at which an explosion is possible. Above this limit, the mixture is too rich to cause an explosion. The UEL is…
  • Upper-class operating area
    In an upper-class operating area, hazardous substances are present in quantities that reach or exceed the quantity thresholds specified in column 5 of the list of substances stated in Annex I to the Major Accidents…
  • Urban land-use planning
    The purpose of urban land-use planning is to prepare and guide the development or other uses of land within the municipality in accordance with the Building Code (BauGB). Key instruments of urban land-use planning…
  • Urban sound design
    Urban sound design focuses on the overall acoustic experience in urban environments. Building on the principles of conventional noise control, it aims to incorporate positive and desirable sound experiences into the…
  • Usability
    Describes how easy and intuitive a device is to use.
  • Usability test
    Assessment of the usability of devices, programmes or apps by a trained panel.
  • User Interface (UI)
    The graphical user interface of a device.  

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