A continuous-wave ultrasonic Doppler system using wide field ultrasound transducers was applied to telemeter blood velocity from the carotid artery of exercising subjects. Velocity spectrogram was obtained by Hanning windowed fast Fourier transformation of the telemetered data. Distortion caused by a high-pass filter and transducers in the telemetry system was discussed in the paper. As the maximum Reynolds number in our experiment was 1478 which is smaller than the critical level of 2000, the blood flow should be laminar. Spatial velocity profiles were then reconstructed from the velocity spectrogram. In this paper, we defined a converging index Q of the velocity spectrum to measure the bluntness of the spatial velocity distribution across the blood vessel. Greater Q, the blunter the velocity profile will be. Simulation results for spatial velocity distributions of theoretical parabolic flow and Gaussian-distribution spectra with varied Q value showed that the cut-off effect by a high-pass filter of cut-off frequency fc=200Hz in our system could be ignored when the axial velocity is larger than 0.30 m/s and Q is greater than 2.0. Our experimental results, in contrast to those obtained from phantom systems by us and by Hein and O'Brien, indicate that the distribution of blood velocity is much blunter than previously thought. The Q index exceeded 10 during systole, whereas it was 0.5 in parabolic flow. The peak of Q index lagged behind that of axial blood velocity by approximately 0.02s. The phase delay of the Q index curve might be due to the time needed for the red blood cells to form the non-homogeneous distribution.

In this paper, we describe a distributed paged-object server to efficiently support the storage management for new generation database management systems. This storage server is based on distributed client/server architecture, and allows clients to directly map database files onto distributed shared virtual memory (DSVM). In this architecture, there is a server at each site and the server only supports the clients in the same site. This improves performance utilizing client machine resources and offloading the shared resourcer server machine and the network. Therefore, this architecture may avoid drawbacks such as bottleneck in a traditional centralized client/server architecture, and also may reduces network traffic and improve performance efficiency of remote file access using Net File System (NFS). Moreover, this architecture allows distributed shared objects to reside and execute anywhere and to be used by any clients on the network. A prototype system (called WAKASHI/D) is implemented under the Mach operating system. The distributed, shared, and transactional virtual memory that the system supports is either volatile or persistent and they can be accessed by user applications in a uniform way. This paper also presents a performance evaluation and analysis of WAKASHI/D to compare its centralized version WAKASHI/C and demonstrates that the distributed server has substantial performance benefits.

In general, multimedia files are much larger than ordinary text files because they consist of multiple monomedia. In order to process large multimedia files in real time, the file system must be able to store and access files efficiently. In th UNIX s5 file system, a multimedia file may be scattered into many disk blocks over the entire disk space, and accessing a multimedia file requires a considerable amount of time for random disk head movement. This paper proposes the internal structure of a multimedia file and its inode which is modified from UNIX s5 file system's. Also, we propose a mechanism for allocating and deallocating contiguous disk blocks for large multimedia files using the bitmap tree and compares its performance with that of the UNIX s5 file system. Our results show that the proposed mechanism reduces considerably the number of disk I/Os required to allocate and deallocate contiguous disk blocks. It also reduces the total access time for large multimedia files by approximately 95% due to the contiguous allocation of disk spaces.

Efficient retrieval of nested objects is an important issue in advanced database systems. So far, a number of indexing methods for nested objects have been proposed. However, they do not consider retrieval of nested objects based on the set comparison operators such as and . Previouly, we proposed four set access facilities for nested objects and compared their performance in terms of retrieval cost, storage cost, and update cost. In this paper, we extend the study and present refined algorithms and cost formulas applicable to more generalized situations. Our cost models and analysis not only contribute to the study of set-valued retrieval but also to cost estimation of various indexing methods for nested objects in general.

In this paper, we propose a register file with data bypassing function. This register file bypasses data using data bypassing units instead of functional units when actual operation in functional units such as ALU is unnecessary. Applying this method to a general purpose microprocessor with benchmark programs, we demonstrate 50% power consumption reduction in functional units. Though length of bus lines increases a little due to an additional hardware in register file, as buses are not driven when data is bypassed, power consumption in bus lines is also reduced by 40% compared with the conventional architecture.

In this paper, the diffusion parameter-values in the K+-ion diffused waveguides made by diluted KNO3 with NaNO3 in the soda-lime glass, which are determined from measured values of the effective index, are presented together with a simple method for the determination. The surface-index changes are measured for the waveguides by KNO3 melts with 75%-, 50%- and 30%-dilutions (weight ratio), and for comparison purpose, also by the pure KNO3, and the dependence of the index-profile on the dilution of KNO3 in the ion-source melt is shown. Change of the two-dimensional index profile in the diffused channel waveguide with the KNO3-dilution is also shown, which is calculated with the measured diffusion parameters.

The organization of the proposed file and algorithms for search and maintenance of the file are simpler than those of a similar key search file based on B+-tree. An experiment using 230,188 keys with length 1-16 shows the good performance of the file. The storage utilization of the file is about 68%.

Multifrequency microwave radiometry has been investigated for non-invasive measurement of temperatures in a human body. In this paper, we propose a new temperature profile model function, which is based on thermo-physiological considerations, for use in model fitting method of retrieving a temperature profile from a set of multifrequency radiometric data. The microwave radiometric technique using the new model function was tested by numerical simulations against animal experiment and clinical data reported elsewhere. The results show that the microwave radiometric technique can be used effectively to measure temperature profiles in tissues over a depth range from 0 to about 4.5 cm.

A problem of synthesizing an optimal file transfer on a file transmission net N is to consider how to distribute, with a minimum total cost, copies of a file J with some information from source vertex set S to all vertices of N by the respective vertices' copy demand numbers. The case of |S| =1 has been studied so far. This paper deals with N such that |S|1, where a forest-type file transfer is defined. This paper proposes a polynomial time algorithm to synthesize an optimal forest-type file transfer on such N satisfying SM U, where M and U are mother vertex set and positive demand vertex set of N, respectively.

Microwave radiometry has been investigated for non-invasive measurement of temperature in human body. Recent trends are to explore the capability of retrieving a temperature profile or map from a set of brightness temperatures measured by a multifrequency radiometer operating in a 1-6GHz range. The retrieval of temperature from the multifrequency measurement data is formulated as an inverse problem in which the number of independent measurement or data is limited (7) and the data suffer from considerably large random fluctuations. The standard deviation of the data fluctuation is given by the brightness temperature resolution of the instrument (0.04-0.1K). Solutions are prone to instabilities and large errors unless proper solution methods are used. Solution methods developed during the last few years are reviewed: singular system analysis, bio-heat transfer solution matched with radiometric data, and model-fitting combined with Monte Carlo technique. Typical results obtained by these methods are presented to indicate a crosssection of the present-state-of-the-development in the field. This review concludes with discussions on the radiometric weighting function which connects physical temperatures in object to the brightness temperature. Three-dimensional weighting functions derived by the modal analysis and the FDTD method for a rectangular waveguide antenna coupled to a four layered lossy medium are discussed. Development of temperature retrieval procedures incorporating the 3-D weighting functions is an important and challenging task for future work in this field.

A problem of obtaining an optimal file transfer on a file transmission net N is to consider how to distribute, with a minimum total cost, copies of a file with some information from a vertex of N to all vertices of N by the respective vertices' copy demand numbers (i.i., needed numbers of copies). The maximum number of copies of file which can be made at a vertex is called the copying number of the vertex. In this paper, we consider as N an arborescence-net with constraints on copying numbers, and give a necessary and sufficient condition for a file transfer to be optimal on N, and furthermore propose an O(n2) algorithm for obtaining an optimal file transfer on N, where n is the number of vertices of N.

An encoder of a trellis coded modulation (TCM) is composed of a linear convolutional encoder followed by a mapper to channel signals. A new condition, under which the performance evaluation of the TCM is possible based on the 2ν state error state transition diagram, is proposed, where ν is the number of delay elements in the convolutional encoder. There have been proposed three similar methods. This paper points out the restriction of the previous methods, and proposes a new method. The condition, under which the previous method is useful, is called nuiformity, such as, the error weight profile is independent from the encoder state. When uniformity does not hold, we discuss to divide an error state into substates based on the coset decomposition of output vectors of the convolutional encoder. The coset is determined by the vector called coset selector. If the condition defined as equal dividing holds, the subdivided states can be merged and the performance can be evaluated based on the 2ν state transition diagram, even for the codes without uniformity. When the row rank of the transformation matrix, from the input vector of the encoder to the coset selector vector, is full, the equal dividing condition holds under the assumption of equally probable i.i.d. (independently identically distributed) input sequence. For TCM schemes without uniformity (in the case, previous methods can not be applied), upper bounds of the bit error rate are evaluated by the proposed method and compared with the simulation results. The difference is less than 10% in the range of bet error rate 10-4.

A stored channel simulator for digital mobile radio enviroments is proposed, which enables the field tests in the laboratory under identical conditions, since it can reproduce the actual multipath radio channels by using the channel impulse responses (CIR's) measured in the field. Linear interpolation of CIR is introduced to simplify the structure of the proposed simulator. The performance of the proposed simulator is confirmed by the laboratory tests.

The propagation characteristics of nonlinear TE waves guided by planar optical waveguide whose guiding region has arbitrary inhomogeneous refractive-index profile are investigated theoretically by using the WKB method. The effects of inhomogeneous index profile of a guided region on the propagation characteristics such as the propagation constant and the field distribution are estimated numerically.

This paper discusses methods and numerical simulations of one and two dimensional profilings for an arbitrary convex conducting target using the electromagnetic backscattering. The inversions for profile reconstructions are based upon the modified extended physical optics method (EPO). The modified EPO method assumes the modified physical optics current properly over the entire surface of conducting scatterers. First, the cross sectional area along a line of sight is reconstructed by performing iteratively the Fourier transform of the backscattering field in the frequency domain. Second, the two dimensional profile is reconstructed by synthesizing the above one dimensional results for several incident angles. Numerical simulation results of the target profiling are shown for spheroids and cone-spheroid.

In a file transmission net N with vertex set V and arc set B, copies of a file J are distributed from a vertex to every vertex, subject to certain rules on file transmission. A cost of making one copy of J at each vertex µ is called a copying cost at µ, a cost of transmitting one copy of J through each arc (x, y) is called a transmission cost (x, y), and the number of copies of J demanded at each vertex u in N is called a copy demand at u. A scheduling of distributing copies of J from a vertex, say s, to every vertex on N is called a file transfer from s. The vertex s is called the source of the file transfer. A cost of a file transfer is defined, a file transfer from s is said to be optimal if its cost is not larger than the cost of any other file transfer from s, and an optimal file transfer from s is said to be optimum on N if its cost is not larger than that of an optimal file transfer from any other vertex. In this note, it is proved that an optimal file transfer from a vertex with a minimum copying cost is optimum on N, if there holds M U where M and U are the mother vertex set and the positive demand vertex set of N, respectively. Also it is shown by using an example that an optimal file transfer from a vertex with a minimum copying cost is not always optimum on N when M ⊃ U holds.

With rapid increase of information requirements from various application areas, there has been much research on the efficient information retrieval. A signature is an abstraction of information, and has been applied in many proposals of information retrieval systems. In this paper we evaluate the performance of various signature-based information retrieval methods and provide guidelines for the most effective usage to a given operational environment. We derive analytic performance evaluation models of these access methods based on retrieval time, storage overhead and insertion time. The relationships between various performance parameters are thoroughly investigated. We also perform simulation experiments by using wide range of parameter values and show that the performance experiments agree with those analytic models.

Compared to multi-level signature file techniques, PSF (Partitioned Signature File) technique has less processing overhead by its characteristics of a simple file organization. In a multi-processor environment, the PSF technique also has an advantage that queries can be processed in parallel effectively by allocating one or more partitions to each processor. Main point of the PSF technique is a partitioning scheme based on a key selection. In this paper, an n-BFK (n-Bounded Floating Key) partitioning scheme is proposed, in which the number of segments for a key selection is bounded by n. The cost model is developed for the performance evaluation of the proposed scheme. By performance comparison with the existing schemes, the efficiencies of the proposed scheme are shown with respect to a disk access cost, a signature reduction ratio, and an uniformity of workload.

This paper proposes the GDV system, which provides a format-independent interface with which to access documents in various formats. It also proposes a new approach for document representation to be used in the GDV system. In this approach, a document is represented by a chain of objects, each of which belongs to a certain class and transforms access operations according to the class-specific transformation rule. A user's request is interpreted as a request to the uppermost object of the chain, transformed by objects in the chain successively, and executed by the lowermost object in the chain. The initial state of a document is an object chain containing an unidentified object. As the unidentified object identifies and divides itself, classification (and chain generation) proceeds step by step.

Voyager Neptune radio science data were collected using three antennas on Earth on August 25, 1989. A parabolic antenna at Canberra, Australia, of 70 meter diameter received 2.3GHz and 8.4GHz carriers. The 64 meter parabolic antennas at Parkes. Australia and Usuda, Japan, received only the 8.4GHz and only the 2.3GHz carriers, respectively. It is necessary to reduce the frequency variation in the received signal carrier to extract accurate information on physically interesting objects such as Neptune's atmosphere, ionosphere, or the rings. After the frequency stabilization process, the frequency drift was reduced from 180Hz down to a maximum of 5Hz, making it possible to reduce the data bandwidth and, consequently, the data volume, by a factor of 30. The uncertainty of the signal frequency estimates were also reduced from 5 down to 510-3Hz/sec above the atmosphere, from 5 down to 0.5Hz/sec in the atmosphere, and from 50 down to 3Hz/sec at the beginning and the end of the atmospheric occultation. Much of the remaining uncertainty is due to scintillations in Neptune's atmosphere and cannot be reduced further. The estimates are thus meaningfully accurate and suitable for scientific analysis and coherent arraying of data from different antennas. Two results based on these estimates are shown: a preliminary temperature-pressure (T-p) profile of Neptune's atmosphere down to a pressure level of 2 bar computed using the Usuda 2.3GHz data, and a multipath phenomenon in the atmosphere seen in Canberra 8.4GHz data. Our T-p profile shows good agreement with the results presented by Lindal et al. within 1K below 100mbar pressure level, even though our result is based on an independent data set and processing. A comparison of the multipath phenomena at Neptune with that at Uranus implies that it was created by a cloud layer with a smaller scale height than the atmosphere above and below it. The processing methods described were developed in part with the interest to coherently array Canberra, Parkes and Usuda data. In this sense, while this paper does not extend any science results, the observations and results are derived independently from other published results, and in the case of Usuda, are completely new.