This letter presents a method for analyzing single server queueing models having two classes of customers. This method, based on the conservation laws, makes it possible to analyze queueing models for various types of queueing disciplines.

We are given a polygonal region P with holes and one point q is specified in the region. The problem is how fast we can find the portion of the boundary of P that is visible from q. For this problem an efficient algorithm is presented which runs in time O(n log h) in the worst case and in time O(n+h log h) if every hole is a convex polygon, where n is the total number of vertices of P and h is the number of holes.

The following problem is considered: Given a rectilinear simple polygon P and a point q in its exterior, find the region that is reachable from q along orthogonal paths with at most k bends. For this problem we preset an efficient algorithm which runs in O(kn) time, where n is the number of vertices.

Mass transport was first employed in an OMVPE system for 1.55 µm GaInAsP/InP laser. The wafers grown by OMVPE were treated at 700 under cracked PH₃ and H₂+N₂ atmosphere for 1 hr, resulting in buried structure and the BH laser showed low threshold current of 50 mA (pulsed) without optimization.

A method for stereo matching is presented. Matching is searched between the edge segments of left and right images based on the features of the segments. A segment is a part of an edge line that is bounded by edge tips, branching points, or points of extremal y-coordinates.

This letter presents the construction of a high-speed time division switching system for the video network, using Si-bipolar super-high-speed RAMs and ECL 100 K families. A switching speed of 256 Mb/s and a switching throughput of 2 Gb/s (signal speed 32 Mb/s64 channels) are obtained.

A laser diode wavelength-division demultiplexer is first proposed. The worst crosstalk level in the 1.30 µm-channel is measured to be less than -33 dB for 0.88 µm, 1.30 µm and 1.55 µm wavelength signals. The free-carrier absorption loss is found to play a significant role in the crosstalk improvement.

This letter presents a method for removing undesirable push actions introduced by a lookahead solution from stack-controlling LALR(1) parsers. By this method, the same parsing algorithm can be surely used for all stack-controlling LALR(1) parsers.

An error-correcting parsing method for context-sensitive languages is described, which finds all sentences ω's in a language with the minimum weighted Levenshtein distance WLD (ω, T) for input string T. The method is obtained by adding an error-correction mechanism to the Adachi-Kamata's parsing method for context-sensitive languages. By introducing the notion of a WLD-graph we can split the error-correction mechanism from the derivation of sentence i.e., the construction of derivation graphs. This makes the algorithm conceptually simple and easy to understand.

The so-called level-crossing problem of a random process is concerned with the properties of a sequence of time points at which the random process crosses with a fixed level. In order to intuitively understand the various properties of the level-crossing problem, we employ the ransom excursion model as a simple mode of a random process, by which the level dependence of the fluctuation of the number of the crossing points is derived for Gaussian processes having modified lowpass spectra. The comparison of the derived result with exact calculation is satisfactory. Secondly, we estimate how the magnitude of the fluctuation of the number for a narrow bandpass Gaussian process is different from that of an independent point process. Finally we obtain expressions for variance of the lengths of the level-crossing intervals and other quantities for a narrow bandpass Gaussian process and we succeed in interpreting the experimentally obtained behavior of the above variance.

This paper reports an on-line recognition method of Thai characters being composed of curves, and having many complicated and similar shapes. A character stroke is segmented into clockwise and counter clockwise arcs according as the stroke tracing is clockwise or counter clockwise, by making use of eight directional codes and directional differences of stroke tracing. Intuitively described features such as the sequence of stroke arcs, types of arc and relative positions of arcs are utilized for classifying characters. A multi-step classification method is introduced to achieve a good recognition rate. By applying the method to 69 categories (414 data) of Thai characters, a recognition rate of 100% for learning data, and a recognition rate of 96.4% for test data have been obtained.

A boundary element solution for the s-dimensional convective diffusion equation in a steady state is formulated by means of transforming its governing operator into symmetric or selfadjoint operator. The traveling material under consideration is assumed to be orthotropic. The velocity field is also assumed to be uniform or variable in spaces. Simple and two-dimensional examples (s2) are treated in numerical experiments in order to demonstrate the validity of the present formulation. A comparison with standard and upwind finite element solutions is also given. It is shown that the boundary element solution is stable and accurate with respect to the Peclet number and the ratio of orthotropy. Moreover, an example of the variable velocity field is treated using the boundary element model without internal cells. It is finally proved that the present method is an improvement over the usual boundary element method.

This paper discusses a simplified three-dimensional (3-D) calculation method based on FEM (Finite Element Method) developed for the analysis of film heads. The calculation derived from the method allows for reproductive efficiency computation on film heads taking a 3-D configuration into consideration. As the calculation uses a two-dimensional (2-D) analysis program substituted for the full 3-D treatment, this program is, therefore, fast enough to be used interactively. The calculated results show that the head efficiency dependences of taper and yoke patterns are significant. The method is suitable for film heads with complicated geometries, because any individual length or pattern dependences can be calculated quite readily.

An experimental study of a strut-scattering contribution to small parabolic antenna secondary patterns is presented. The test reflector used in the measurement is the one with D (diameter)500 mm and with F (focal length)125 mm. In order to examine the strut effects on the reflector secondary patterns, all the data are measured two-dimensionally with a computer-aided antenna positioner. Two quantities, ψ_s (elevation angle) and φ_s (rotational angle varied from the plane of the source polarization), are introduced as the strut-position parameters. The results of the experiment done at f12 GHz with four struts (10 mm in diameter) show that the reflector patterns are considerably influenced by the strut. When, for example, φ_s0 and _s30, the H-plane first sidelobe level is found to increase to about -15 dB; the value for a non-strut parabola was -20.6 dB. The cross-polar levels are also disturbed. When φ_s45 and _s40, the cross-polar value is deteriorated to -22.5 dB; the corresponding value of a strut-free reflector was -37 dB. The loss of gain for a strut-free parabola was from 0.5 to 1.0 dB in this experiment. It is also experienced that for an one-strut parabola, on-axis cross polarization appears; the amount of which for φ_s45 and for _s70 was about 36 dB.

Assuming a perfect circulary polarized radar system, the cancellation ratio limitations were evaluated using the Sekine-Lind rain-drop distribution. Numerical methods were used and the cancellation limitation was plotted against rainfall rate for various wind velocities.