The Capability Maturity Model (CMM) proposed by the Software Engineering Institute (SEI) of Carnegie Mellon University (CMU) is an effective framework for software process improvement (SPI) because it can increase development productivity and improve software quality for many software development companies. However, the CMM only indicates 'what' needs to be improved, it does not indicate 'how to' perform software process improvement activities (SPIA). In this paper we describe a Software Process Improvement support System (SPIS) that does indicate 'how to' perform SPIA. It is designed to be used mainly for internal SPIA by software development companies and their project teams. The SPIS is composed of seven support tools and promotes SPIA. The tools include a specific capability maturity model (SCMM), rules for assessing a company's maturity level, and an assessor qualification system for organizing the assessment team. These tools were extracted deductively from our experience and have proved to be effective when used for the SPIA at our company. (R): CMM is registered trademarks in the U. S. Patent and Trademark Office. SM: CMM is a service mark of Carnegie Mellon University.

In an optical submarine cable transmission system, small size, low consumption power, and high reliability are required for inline repeaters. The structure of the inline repeater should be a simple single stage. The design of erbium doped fiber (EDF) itself is very important for the inline repeater to achieve broad bandwidth, high output power, and low noise figure. We designed and developed high alumina co-doped erbium doped fiber amplifiers (EDFAs) for long-haul, high-capacity WDM transmission systems. We investigated the trade-off relationship between the gain flatness and the output power to optimize the EDF length. We obtained high performance, including a slightly sloped gain flatness of +0.04 dB/nm at 1550 nm, a superior noise figure of 4.7 dB, and a relatively large output power of +11.5 dBm for an EDF length of 5 m using a 1480-nm pumping laser diode. We applied gain-equalizers (GEQs) using Mach-Zehnder type filters with different FSRs to accurately compensate for the EDFAs ' gain-wavelength characteristics. The main GEQs have free-spectral-ranges (FSRs) of 48-nm, which are about 2 times as long as the wavelength difference between a 1558-nm EDFA gain peak and a 1536-nm EDFA gain valley. Using a circulating loop with the above EDFAs and GEQs, we performed the broad wavelength bandwidth. The achieved signal wavelength bandwidth after 5,958-km transmission was 20 nm. We successfully transmitted 700-Gbit/s (66 10.66-Gbit/s) WDM signals over 2,212 km. The combination of high alumina co-doped silica EDFA and large FSR GEQ is attractive for long-haul, high-capacity WDM transmission systems.

In this paper, we analytically study the effects of overlap and overlay structure on the quality of service (QoS) of Low Earth-Orbital Satellite (LEOS) communication systems. We consider two-layered overlay of cells and intentional overlap of neighboring small cells. In order to measure the QoS, the probabilities of rejection of a newly arrived call (blocking) and forced termination due to failure of a handover (call dropping) are derived. In addition to these measures, the largest traffic intensity which guarantees the required blocking and dropping probabilities is also used.

In modems for burst transmission of digital data, rapid carrier and clock synchronization are essential. Typically, frequency correction occurs prior to phase recovery since estimators are sensitive to frequency offsets. In this paper, we derive the bit error rate (BER) performance of a M-ary phase shift keying (MPSK) receiver in a closed form when there is no frequency offset estimator. Then we derive a relationship of the required burst length for certain BER with frequency offset estimator. To obtain the BER=10-4, approximately we need the burst length of 101 at Eb/N0=10 dB and 69 at Eb/N0=15 dB.

Our recent progress in GaN-based nanostructures for quantum dot (QD) lasers and vertical microcavity surface emitting lasers (VCSELs) is discussed. We have grown InGaN self-assembled QDs on a GaN epitaxial layer, using atmospheric-pressure metalorganic chemical vapor deposition. The average diameter of the QDs was as small as 8.4 nm and strong photoluminescence emission from the QDs was observed at room temperature. Furthermore, we found that InGaN QDs could be formed even after 10 QD layers were stacked, thus increasing the total QD density. Using these growth results, we fabricated a laser structure with InGaN QDs embedded in the active layer. A clear threshold was observed in the dependence of the emission intensity on the excitation energy at room temperature under optical excitation. We succeeded in demonstrating in lasing action in vertical cavity surface emitting lasers at room temperature with a cavity finesse of over 200.

To bridge a wide gap between the end users and the requirements engineers, we propose a business flow diagram for acquiring users' requirements of the object oriented software development in the business application domain. Each field of this diagram shows either a role or a responsibility of a particular person or an organization. This paper proposes a development method that the engineers acquire the requirements by using our diagrams. We have implemented a supporting tool based on this study for collaborating the requirements engineers with their users. At first, the end users of an information system to be developed draw diagrams representing the flows of information and physical objects in their work from their own points of view. Sometimes the engineers write them with the users. If all users submit their diagrams, then our tool collects them and constructs a total diagram. The requirements engineers analyze the total diagram for improving the business flow. After the engineers complete this diagram, our tool can automatically transform it into an initial version of the class diagram. We show the effectiveness of our approach with some experiments. Comparing the related works, we discuss some issues of the practical aspects of this proposal.

A software requirements specification (SRS) is a document at the first phase of software development. Since it is difficult to make an accurate SRS at the beginning of software development, we propose a supporting method to detect and interpret the inconsistency of SRS. First, we classify and define the inconsistency of SRS. Next, we describe how to detect and interpret the inconsistency of SRS. We use the Requirements Frame Model to detect the inconsistency of SRS. We apply the Dempster and Shafer's theory to interpret the inconsistency of SRS. We illustrate our method with an example.

We propose a learning algorithm for simple deterministic languages from queries and a priori knowledge. To the learner, a special finite subset of the target language, called a representative sample, is provided at the beginning and two types of queries, equivalence queries and membership queries, are available. This learning algorithm constructs nonterminals of a hypothesis grammar based on Ishizaka(1990)'s idea. In Ishizaka(1990)'s algorithm, the learner makes rules as many as possible from positive counterexamples, and diagnoses wrong rules from negative counterexamples. In contrast, our algorithm guesses a simple deterministic grammar and diagnoses them using positive and negative counterexamples based on Angluin(1987)'s algorithm.

This paper describes a scheme to capture a wide-view image using a camera setup with uncalibrated cameras. The setup is such that the optical axes are pointed in divergent directions. The direction of view of the resulting image can be chosen freely in any direction between these two optical axes. The scheme uses eight-parameter perspective transformations to warp the images, the parameters of which are obtained by using a relative orientation algorithm. The focal length and scale factor of the two images are estimated by using Powell's multi-dimensional optimization technique. Experiments on real images show the accuracy of the scheme.

The sense of equilibrium is influenced by various factors of visual stimulation, especially far peripheral vision and a motion parallax. An investigation of these two factors was made in order to apply the findings to construct a rehabilitation method for equilibrium disorders. From the experimental results, it was found that the center of gravity for the subjects was greatly affected by both far peripheral vision and the motion parallax. This finding suggests how visual stimulation should be displayed to control the sense of balance in the case of equilibrium disorders.

Continuous-wave operation at room-tempera-ture has been demonstrated for InGaN multi-quantum-well (MQW) laser diodes (LDs) grown on FIELO GaN substrates with a backside n-contact. This was made possible by introducing important new concept of reducing threading dislocations that occur during the growth of the GaN substrates. We found that InGaN active layers grown on FIELO GaN are superior to those grown on conventional sapphire substrates in terms of their growth mode and the resultant In compositional fluctuation. The fabricated laser diode shows the threshold current, the threshold current density and the threshold voltage were 36 mA, 5.4 kA/cm2 and 7.5 V, respectively, with the lasing wavelength of 412 nm and internal quantum efficiency as high as 98%.

The three dimensional (3D) packing problem is to arrange given rectangular boxes in a rectangular box of the minimum volume without overlapping each other. As an approach, this paper introduces the system of three sequences of the box labels, the sequence-triple, to encode the topology of the 3D-packing. The topology is the system of relative relations in pairs of boxes such as right-of, above, front-of, etc. It will be proved that the sequence-triple represents the topology of the tractable 3D-packings which is a 3D-packing such that there is an order of the boxes along which all the boxes are extracted one by one in a certain fixed direction without disturbing other remaining boxes. The idea is extended to the system of five ordered sequences, the sequence-quintuple. A decoding rule is given by which any 3D-packing is represented. These coding systems are applied to design heuristic algorithms by simulated annealing which search the codes for better 3D-packings. Experimental results were very convincing its usefulness as automated packing algorithms.

Bit error rates (BER) for playback of (1,7) code employed in optical disc recording were simulated using an ideal (Gaussian) playback waveform, with playback being performed by PRML (Partial Response Maximum-Likelihood) combining a partial response equalizer and a double clock weighted Viterbi decoder. It was found that best BER occurs for PR(2,3,3,2) +7/10 level Viterbi decoding at a weighted value of w = 0.5 for data consisting of 107 symbols. For a minimum bit length of 0.28 µm, BER of 10-4 and less than 10-6 was obtained for SN ratios of 15.6 dB and 17.7 dB, respectively. And for a minimum bit length of 0.26 µm, BER of 10-4 and less than 10-6 was obtained for SN ratios of 16.7 dB and 18.8 dB, respectively. These results demonstrate the feasibility of a minimum bit length of 0.26 µm in current optical disc recorders.

Let S be a set of n points in the plane and CH(S) be the convex hull of S. We consider the problem of constructing an approximate convex hull which contains CH(S) with strong convexity. An ε-convex δ-superhull of S is a convex polygon P satisfying the following conditions: (1) P has at most O(n) vertices, (2) P contains S, (3) no vertex of P lies farther than δ outside CH(S), and (4) P remains convex even if its vertices are perturbed by as much as ε. The parameters ε and δ represent the strength of convexity of P and the degree of approximation of P to CH(S), respectively. This paper presents the first parallel method for the problem. We show that an ε-convex (8+42)ε-superhull of S can be constructed in O(log n) time using O(n) processors, or in O(log n) time using O(n/log n) processors if S is sorted, in the EREW-PRAM model. We implement the algorithm and find that the average performance is even much better: the results are more strongly convex and much more approximate to CH(S) than the theoretical analysis shows.

In this paper, we propose a method for detecting conserved domains from a set of amino acid sequences that belong to a protein family. This method detects the domains as follows: first, generate fixed-length subsequences from the sequences; second, construct a weighted graph that connects any two of the subsequences (vertices) having higher similarity than a pre-defined threshold; third, search for the maximum-density subgraph for each connected component of the graph; finally, explore conserved domains in the sequences by combining the results of the previous step. From the performance results obtained by applying the method to several protein families that have complex conserved domains, we found that our method was able to detect those domains even though some domains were weakly conserved.

In a phase-locked-loop (PLL) frequency synthesizer with binary phase comparison, jitter is hard to suppress. In this paper, we propose a PLL frequency synthesizer with an improved binary phase comparison which can solve the above problem. The effectiveness of the proposed method is confirmed by PSpice simulation results.

This paper describes a fiber-optic level sensor designed to measure the level of liquid propane-butane in a relatively short range (60 cm) in the top part of storage tanks at oil refineries with the purpose of monitoring the level of this product in the filled or slightly underfilled or overfilled tanks during various measuring operations. A discrete multi-element device employing novel refractometric transducers was selected because it yields both a large measurement range and high resolution. Several innovations offer a competitive advantage to industrial users: 1) Special micro-optical refractometric transducer; 2) Efficient and economical sensor multiplexing scheme; 3) Fast level-tracking operational algorithm. The vertical resolution of the sensor -1 cm, the maximum excess pressure in the tank -40 atm (4 MPa). The sensor has the spark-proof and explosion-proof design and optical fiber interface for the transmission of the output data. The sensor successfully measured liquid propane-butane level in storage tanks during numerous cycles of measuring operations.

The legal firing sequence problem (LFS) asks if it is possible to fire each transition some prescribed number of times in a given Petri net. It is a fundamental problem in Petri net theory as it appears as a subproblem, or as a simplified version of marking reachability, minimum initial resource allocation, liveness, and some scheduling problems. It is also known to be NP-hard, however, even under various restrictions on nets (and on firing counts), and no efficient algorithm has been previously reported for any class of nets having general edge weights. We show in this paper that LFS can be solved in polynomial time (in O(n log n) time) for a subclass of state machines, called cacti, with arbitrary edge weights allowed (if each transition is asked to be fired exactly once).

The pseudo-lattice method has been developed for dynamic 3-D liquid-crystal director simulation in thin-film-transistor liquid-crystal displays. Its feature is that the equation of motion of the director is not formularized from the real-lattices, but from the pseudo-lattices organized between the real-lattices. The director on the pseudo-lattice is calculated from the real-lattices by insertion. The objective is to simulate the continuous nematic symmetry correctly and to reduce time and memory needed for the calculation. Especially in this paper, the pseudo-lattice method is explained in detail. Moreover, experiments have been done, and the simulated behavior and location of the bright line, which is caused by the distortion of the director profile, were confirmed to be the same as the actual ones. In particular, the movement and elimination process of the bright line were simulated for the first time.

A systematic method for connection-wise end-to-end delay analysis in asynchronous transfer mode (ATM) networks is proposed. This method consists of the followings: (i) per-stream nodal analysis; (ii) output processes characterization; and (iii) moment matching scheme. Following our previous work, we employ H-MMPPs/Slotted D/1 to model ATM queues. Each virtual connection (VC) in ATM networks can be regarded as a tandem configuration of such queues. In [1], the per-stream analytical results for such an H-MMPPs/Slotted D/1 queue have been provided. In this paper, not only the composite output process is exactly characterized, but also the component in an output process that corresponds to a specific traffic stream is approximated via a decomposition scheme. A moment matching scheme to emulate the per-stream output process as a two-state MMPP is further proposed. Through moment matching, we can then approximate the connection-wise end-to-end delay by recursively performing the nodal performance analysis. The connection-wise end-to-end delay is crucial to network resource decision or control problems such as call admission control (CAC) and routing.