Abstract: Phosphate-contaminated water passes through a domestic sewage treatment system, in which oxidation of the ammonium progresses far enough to cause a lowering of the pH to 5 or less. The water is passed over sand grains coated with aluminum hydroxide (gibbsite). Enough Al3+ ions enter solution, at the low pH, to cause all the phosphate-P to precipitate as aluminum phosphate, and nothing else precipitates other than the aluminum phosphate.

Abstract: Sun sensors or position sensors may be used to determine the angular location of the sun or other object with respect to the sensor. The sun sensor provides high resolution over a wide field of regard. A position or sun sensor comprises a sensor housing, a plurality of pinholes formed In the sensor housing, a detector mounted within the housing and a method of processing the information detected. The detector is mounted in the sensor housing. Each pinhole has a field of view and the detector receives the images from each field of view. Each field of view is defined by the position of the pinhole relative to the detector. The images are received in an overlay relationship thereby providing a field of regard. The processing method determines the presence and location of an object In a field of regard.

Abstract: The present invention provides a method for distinguishing a boundary of an object, and the object itself, from its background. In the method electromagnetic radiation is detected from at least one field of view substantially spanning the boundary of the object and background adjacent to the boundary and superimposed or overlaid as images onto a detector. The method includes correlating spatial transitions in intensity of the overlaid images on the detector with a boundary of the object. When used for determining the attitude of a satellite with respect to the earth, the detector is a thermal infrared detector thereby providing a sharp contrast between the thermal emission of the earth and cold space. The invention provides a simple, effective method and device for determining satellite orientation and/or attitude with respect to a thermal infrared-emitting target body.

Abstract: The present invention provides a method and device for producing an illusion of weightlessness. An enclosed room having walls, a floor and a ceiling defining an interior is provided. A plurality of visually polarized objects are rigidly secured to the walls, ceiling or floor to indicate an up and down direction. A user is secured into a cushioned user support member mounted in the enclosed room and rotated into the supine posture. The room is then rotated into alignment with the user's body. The room containing a rich variety of visually polarized objects having recognizable tops and bottoms still appears upright when the room and person in the support member are both rotated at an angle of 90.degree. from the upright position. The gravity sense organs in the inner ear (otolith organs) which normally indicate when the head is erect, are not powerful enough in most people to overcome the strong contradictory visual information.