Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2001-10-11
2003-09-02
Bui, Bryan (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S026000, C702S050000, C702S100000
Reexamination Certificate
active
06615145
ABSTRACT:
PRIOR APPLICATIONS
This application bases priority on German application no. 100 51 715.3-52 filed on Oct. 12, 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a procedure for the systematic determination of substances with particle character, moving with a vertical component in a flowing fluid, for the mass accumulation of particle groups in a calibrated sediment trap exposed to flow with knowledge of the actual values of the trap and flow parameters, and to an apparatus for executing this procedure.
2. Description of Prior Art
Materials with particle character, moving with a vertical component in flowing waters and oceans, play an essential role in sedimentological, biogeochemical, biological, climate-relevant, morphological and many other processes. Their systematic determination leads, among others, to detailed results regarding the global cycle of organic carbon and nutrients. Likewise, many technical installations with moving fluids require information about the vertical mass flux of embedded substances with particle character. In connection with the present text, the term “materials with particle character” is to be understood as representing both particles consisting of solids (either fully solid or aggregated) in the sense of “particles” as well as particles consisting of gas bubbles or solid-gas combinations. Depending on relative density of the particle type it experiences, either a sinking force (sinking materials) or a buoyancy force (raising materials). In the state-of-the-art, the major group considered in connection with sediment traps is that of sinking particles, which is the reason why the following text mostly refers to this type. The devices used according to the state-of-the-art for determination of the vertical mass flux (so called “sediment traps”) collect—even at the same measuring location—individually different amounts of sinking particles due to the different collection and extraction procedures and apparatus used. For these cases the prominent task was to determine qualitatively and quantitatively the composition of the pool of a sinking substance with particle character rather than to determine the “in-situ mass flux” of the different sinking particle groups it is comprised of in the sense of knowledge of the exact values of actually sinking mass and the detailed sinking processes in the fluid. The equation used accordingly by which the so called “trap flux” is determined by dividing the particle mass collected in the sediment trap by collection time and total area of the trap aperture (the opening area of a sediment trap), only permits one to calculate the mass flux of sinking particles and related variables in the open water column for fluids without motion.
In case the fluid carrying particles moves with a horizontal flow component towards the trap aperture which is typically horizontally aligned, then the actual collection process in the trap is strongly altered by the approach velocity in comparison with the sinking or sedimentation process in the free water column or at the bottom, respectively. A circulation pattern of the fluid is generated which is coupled to the approaching flow in the entrance zone of the trap, which thus is continuously flushed by new fluid. This “circulation zone” permits particles embedded in the fluid to reach not only gravimetrically but also advectively the inner space of the trap from where a fraction settles. This holds for particles with a sinking speed larger than 5 m/day, slower-sinking particles, whose fraction of the total mass flux is mostly less than 10%, can only be collected by other techniques. The flow-influenced collection process of sinking substances with particle character cannot be quantified by the classical trap flux equation for non-moving fluid (mentioned above) and is reflected mathematically in semi-empirical “accumulation equations”, by the help of which from the measured mass accumulation of a known, calibrated type of trap the in-situ mass flux of a single particle group can be calculated.
Here, the term “type of trap” is to be understood as a trap parameter specification based on coefficients related to an individual trap as sub-group of a “trap family” as the higher classification level. Such accumulation equations exist for different trap families, in particular for cylindrical and conical traps (see Reference 1 of Gust et al: “Mooring Line Motions and Sediment Trap Hydromechanics: In-Situ Intercomparison of Three Common Deployment Designs” 1994, Deep Sea Research 41, 831-857 and Reference 2 of G. Gust et al.: “Particle Accumulation in a Cylindrical Trap under Laminar and Turbulent Steady Flow: An Experimental Approach” 1996, Aquatic Sciences 58, 297-326) and plate traps (see Reference 3 by B. Westrich ‘Fluvialer Feststofftransport-Auswirkungen auf die Morphologie und Bedeutung fuer die Wasserguete’ 1988, Schriftenreihe Wasser-Abwasser 22, R. Oldenbourg Verlag, Muenchen, Wien, pages 24-29). The development of additional accumulation equations for other trap families is presently a research task. These can be incorporated without problem into the invention described here since they will be based on the same basic concepts. Particularly, Reference 2 provides basic explanations for the mass accumulation of particle groups in a calibrated sediment trap under flow as basis for the invention presented here. An excerpt for the necessary understanding of the invention is offered in the following. The accumulation equations presented in References 1 and 2 show that sediment traps of cylindrical and conical geometry operate on a basically different particle-collection principle compared to plate traps with flat, hydraulically smooth or rough surfaces. For example, for plate traps (see patent DE 197 37 448 A1) the particles settle immediately from the moving fluid onto the trap surface as soon as the deposition stress is larger than the counteracting flow-induced bottom stress at the collection location. In case the flow-generated bottom stress exceeds this value, the particles cannot settle any more. If the bottom stress reaches with increasing flow speed the critical bottom stress, then the particles which had already settled on the collection surface are eroded again. The plate traps thus provide a mean value of mass for experiment duration and collection area, which depends on the deposition stress of the sinking particles, on the flow-generated bottom stress, on the critical bottom stress for erosion of deposited particles as well as on the respective initial concentration of particle groups with different settling velocities. In contrast, for sediment traps with hollow geometry the accumulation process under flow leads via a trap-internal circulation pattern which is coupled to the outer flow and whose fluid flushing rate depends on the velocity of the approaching fluid. From the deepest section of this circulation zone where the particles are carried along with the fluid while sinking, a fraction of particles as described by the so called “yields function” is transferred into the underlying quiescent fluid zone where the particles are moving downwards exclusively by their sinking velocity and eventually settle on the collection surface. This type of collection process leads via the experiment duration to the cumulative increase of mass collected (mass accumulation). The quiescent zone beneath the circulation zone is required in both design and function and exists only for a proper length-width ratio of the trap geometry.
For a single, vertically aligned sediment trap the following accumulation equation holds for a substance comprised of a mixture of sinking particles (Gust et al., 1996)
M
TP
=&Sgr;(
M
T
)
n
=&Sgr;y
(
u
a
,w
sn
)
c
0n
t
(
Q
(
u
a
)+
A
s
w
sn
) [1]
For a single conical trap, a dependency of simular mathematical structure but with additional controlling parameters is assumed:
M
TP
=&Sgr;(
M
T
)
n
=&Sgr;(
y
(
u
a
,w
sn
,TKE
)
c
0n
t
(
Q
(
u
a
)+
A
s
W
sn
)) [2]
Bui Bryan
Larson James E.
Larson & Larson, PA
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