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Abstract. In the field of requirements engineering, measuring inconsistency is crucial to effective inconsistency management. A practical measure must consider both the degree and significance of inconsistency in specification. The main contribution of this paper is providing an approach for measuring inconsistent specification in terms of the prioritybased scoring vector, which integrates the measure of the degree of inconsistency with the measure of the significance of inconsistency. In detail, for each specification ∆ that consists of a set of requirements statements, if L is a m-level priority set, we define a m-dimensional priority-based significance vector − → V to measure the significance of the inconsistency in ∆. Furthermore, a priority-based scoring vector − → SP : P(∆) → N m+1 has been defined to provide an ordering relation over specifications that describes which specification is "more essentially inconsistent than" others.

We introduce some new perfect state transfer and teleportation schemes by quantum walks with two coins. Encoding the transferred information in coin 1 state and alternatively using two coin operators, we can perfectly recover the information on coin 1 state at target position only by at most two times of flipping operation. Based on quantum walks with two coins either on the line or on the N -circle, we can perfectly transfer any qubit state. In addition, using quantum walks with two coins either on complete graphs or regular graphs, we can first implement perfect qudit state transfer by quantum walks. Compared with existing schemes driven by one coin, more general graph structures can be used to perfectly transfer more general state. Moreover, the external control of coin operator during the transmitting process can be decreased greatly. Selecting coin 1 as the sender and coin 2 as the receiver, we also study how to realize generalized teleportation over long steps of walks by the above quantum walk models. Because quantum walks is an universal quantum computation model, our schemes may provide an universal platform for the design of quantum network and quantum computer.

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In the past few years, there has been considerable research and interest in a topic known by various names, such as Time Reverse Acoustics (TRA), Time Reverse Mirrors (TRM), and Time Reverse Cavities (TRC), which exploits reciprocity and the time symmetric property of the wave equation. Very little of this work has been directed at the seismic exploration imaging problem. In fact, most of the work has had application in sonar, medical and non-destructive testing applications. Here we present some initial results of applying this technology to the seismic imaging of a salt dome flank. We create a set of synthetic traces representing a multi-level, walk away VSP for a model composed of a simplified Gulf of Mexico vertical velocity gradient and an embedded overhanging salt dome. To process these data, we first apply the concepts of TRA to the synthetic traces. This creates a set of stacked traces without having to perform any velocity analysis or complicated processing. Each of these stacked traces is equivalent to the output of a spatially coincident, or zero offset, down hole source and receiver pair. Thus we have the equivalent of a zero offset seismic section as if it were collected from down hole sources and receivers. After having applied the TRA concepts, we then apply conventional post stack depth migration to this zero offset section to produce the final image of the salt dome flank. Our results show a very good image of the salt. In fact, the image created is nearly identical to an image actually using data from down hole, zero offset source and receiver pairs. The simplicity of the TRA implementation provides a virtually automated method to create a stacked section as if it had been collected from the reference frame of the borehole containing the VSP survey. IntroductionTime Reverse Acoustics (TRA) is a part of a set of closely related technologies which have been evolving over the past few years by researchers in several fields. As such, it is been referred to by terms like Time Reverse Mirrors, Time Reverse Acoustics, and Time Reverse Cavities (e.g. Derode et al., 2000;Fink, 2000 Fink, , 2001Jonsson et al, 2004). Much of this work pertains to measuring a recorded wave field from a sound source in a physical experiment, time reversing the recorded pressures, and then re-injecting the time reserved waveforms into the medium at the recording locations. The result of this process effectively back propagates the signal to the original sound source location. This is highly effective, for example, in deriving the beam steering parameters to focus a blast of ultrasonic sonic energy created by an array of sources located outside of a person's body to heat and destroy internal tumors in medical treatment applications. In this paper we extend the notion of time reverse acoustics to the seismic exploration problem.Since the 1980's there has been much work done on the topic of reverse time migration of seismic data (e.g. Whitmore, 1983;Baysal et al, 1983; Levin, S.A., 1984; Hellman et al, 1986; Chang and ...

We describe a new shortcut strategy for imaging the sediments and salt edge around a salt flank through an overburden salt canopy. We tested its performance and capabilities on 2D synthetic acoustic seismic data from a Gulf of Mexico style model. We first redatumed surface shots, using seismic interferometry, from a walkaway vertical seismic profile survey as if the source and receiver pairs had been located in the borehole at the positions of the receivers. This process creates effective downhole shot gathers by completely moving surface shots through the salt canopy, without any knowledge of overburden velocity structure. After redatuming, we can apply multiple passes of prestack migration from the reference datum of the bore-hole. In our example, first-pass migration, using only a simple vertical velocity gradient model, reveals the outline of the salt edge. A second pass of reverse-time, prestack depth migration using full two-way wave equation was performed with an updated velocity model that consisted of the velocity gradient and salt dome. The second-pass migration brings out dipping sediments abutting the salt flank because these reflectors were illuminated by energy that bounced off the salt flank, forming prismatic reflections. In this target-oriented strategy, the computationally fast redatuming process eliminates the need for the traditional complex process of velocity estimation, model building, and iterative depth migration to remove effects of the salt canopy and surrounding overburden. This might allow this strategy to be used in the field in near real time.

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