摘要:
A method to determine the systematic error of an instrument that measures features of a semiconductor wafer includes the following sequential steps. Collecting sensor data from measurement runs on front and back surfaces of a wafer while the wafer is oriented at different angles to the instrument for each run, yielding a front data set and a back data set for each angle. Then organizing the data in each set into a wafer-fixed coordinate frame. Reflecting all back surface data about a diameter of the wafer creates a reflected back data set. Subtracting the reflected back data from the front data for each wafer angle, and dividing the result by two, yields an averaged wafer shape for each load angle. Adding the reflected back data to the front data and dividing the result by two, yields an instrument signature for each load angle. The symmetric corrector is calculated by taking the average over all instrument signatures at each load angle. The symmetric corrector is successively rotated to the same angle as a front shape measurement and subtracted, yielding a calibrated wafer data set. A wafer mean is computed by averaging these calibrated wafer shape measurements. When the wafer mean is subtracted from the individual front side corrected shape measurements, a set of shape residual maps for each load angle results. The average of the aligned residuals is the asymmetric error. The systematic error is the sum of the symmetric and asymmetric errors.
摘要:
A data management system for managing the storage of data on primary and secondary storage from a primary information source having original file content to be stored including: a data file stub stored on primary storage; a data file stored on secondary storage; and wherein: the data file stub comprises original file meta data and additional stub meta data relevant to the data file; the data file comprises the original file content and additional file meta data relevant to the data file stub; the additional stub meta data includes location and information relevant to locate and recover the data file; the additional file meta data includes information relevant to the location and content of the stub; the additional stub meta data and additional file meta data being so formed and arranged that the data to be stored may be accessed without stateful middleware.
摘要:
A modular measurement while drilling sensor assembly is presented. A typical cross-over assembly for mating with a measurement while drilling (MWD) tool is connected to a typical positive displacement mud motor (e.g., a Moineau motor). A modular sensor assembly comprises two portions, an upper drive shaft portion which includes a flexible shaft connected to the motor and a lower sensor portion and supported by a radial bearing. The lower end of the flexible shaft is connected to a hollowed shaft which extends beyond the lower end of the upper drive shaft portion and which is supported by a radial bearing. The lower sensor portion has a central channel extending longitudinally therethrough, with the lower portion of the hollowed shaft extending through this channel. The sensor portion may comprise any type of MWD sensor, however the present invention is preferably used with sensors (e.g., formation evaluation sensors) that benefit from obtaining measurements close to the bit. The lower end of the hollowed shaft is supported with a radial bearing and connected to a flexible shaft of an adjustable kick off assembly connected to the sensor portion. The adjustable kick off assembly allows the introduction of a kick off angle, generally between 0.degree. and 3.degree., in the assembly. The adjustable kick off assembly is connected to a typical bearing pack assembly. The lower end of the bearing pack assembly is typically connected to a drive shaft, a bit box and then the bit.
摘要:
Geophysical measurement system employed during the drilling of a well borehole. The system employs a reference clock disposed within equipment at the surface of the earth and a borehole assembly which houses a downhole clock and at least one sensor. The borehole assembly is operationally connected to a drill string, which advances the borehole. At least one synchronization shuttle apparatus containing a shuttle clock is conveyed downhole to the borehole assembly to synchronize the borehole clock with the reference clock. Reference and borehole clock synchronization is maintained at one millisecond or less over a period of days. Outputs from the reference clock and borehole clock and sensor are combined to obtain a measure of a geophysical parameter of interest. Although the measurement system is particularly applicable to seismic-while-drilling measurements, it can be used in a wide variety of clock driven geophysical measurements.
摘要:
A layer of plastics material is applied to at least one selected surface of a metal article by a method in which the article is heated and positioned in such a way that the selected surface or surfaces is or are lowermost; a table having an upper surface or surfaces carrying a layer of powdered plastics material, said carrier surface or surfaces of the table being of a shape and area such that the surface or surfaces will wholly underlie the selected surface or surfaces of the article, is raised upwardly beneath the article to urge said carrier surface or surfaces against the overlying selected surface or surfaces and so transfer powder from the carrier surface or surfaces to the selected surface or surfaces; and the powdered material adhering to the selected surface or surfaces is permitted or caused to coalesce and form a plastics layer on the or each surface. Preferably powdered plastics material is applied to the carrier surface or surfaces by raising the table upwardly through a fluidized bed of powdered plastics material.
摘要:
A binding device (300) is useful for securing materials such as booklets and magazines in a ring binder. The device (300) has a perforated side (305) including holes (315) for securing the device (300) in a ring binder. A clamping side (310) includes an upper jaw (320) and a lower jaw (325). The upper jaw (320) and the lower jaw (325) each include a component (335) of a snap fit mechanism for securing the upper jaw (320) and the lower jaw (325) together along a longitudinal axis of the device (300).
摘要:
An optical cable, especially suitable for use as an aerial cable, comprises a circumferentially rigid flexible tube which is of composite form and comprises a plurality of elongate flexible bodies helically laid up together, each of which bodies is of a cross-section approximating to a sector of an annulus and comprises extruded electrically insulating plastics material and a mulitiplicity of longitudinally stressed elongate flexible non-metallic reinforcing elements encapsulated in said plastics material, e.g. polypropylene or nylon, the multiplicity of non-metallic reinforcing elements being substantially evenly distributed throughout the cross-sectional area of the body. An outer protective non-metallic sheath surrounds the tube and at least one flexible optical guide, e.g. a separate optical fibre, optical bundle or optical fibre ribbon structure, is housed in the bore of and is movable relative to the tube.
摘要:
A simple and inexpensive dead end fitting for securing an overhead conductor loosely housing an optical guide to a tower comprises a sleeve of malleable metal or metal alloy, open at each of its ends, for compression jointing to the conductor; a steel termination in screw threaded engagement with the sleeve and having a clevis for securing the fitting to a tower; and a lug welded to the sleeve for effecting electrical connection to a jumper cable. The lug engages in a notch in the adjacent end of the termination to lock positively the screw threaded engagement between the sleeve and termination.
摘要:
In an inexpensive and simple method of effecting a joint between two overhead electric conductors incorporating optical fibres or between an overhead electric conductor incorporating an optical fibre and an optical cable extending to a sub-station or other location, at least a part of each or the overhead conductor is introduced into a metal sleeve extending from a wall of a metal housing and the sleeve is compression jointed to the conductor to effect a mechanical and electrical joint between the conductor and the housing. The part of the conductor protruding into the housing is cut back and a joint is effected between the optical fibres of the two overhead conductors or between the optical fibres of the overhead conductor and the optical cable that has been introduced into the housing. The housing is sealed to render it fluid tight and is preferably filled with petroleum jelly. An elongate metal shroud may be assembled around the metal housing and be so shaped as to provide aerodynamic and corona protection.
摘要:
An electric cable support system is provided having means for supporting electric cables and an elongate metal duct housing said support means and divided transversely into separately formed parts that are detachably secured together, the internal surface of at least a part of the length of the elongate duct is lined with a continuous wall of thermal insulating material and/or absorbing material comprising a closed envelope, or at least two closed envelopes arranged adjacent one another, containing non-flammable evaporative cooling fluid. Preferably, the or each envelope is made of a flexible material which will melt at a temperature at or near the boiling point of the cooling fluid. In the event of an external fire, when the temperature of the duct wall is sufficient to melt the flexible material of an envelope, the cooling fluid will start to evaporate and cool the duct interior.