Capacity enhancement of cellular CDMA by traffic-based control ofspeech bit rate

Variable rate speech coding is now recognized as an important system component for high-capacity cellular networks because it exploits speech statistics to reduce the average bit rate, which results in reduced interference and increased capacity. Once a variable rate capability is available, an additional capacity enhancement can be achieved by introducing network control of the user bit rate in response to changing traffic levels. We introduce the concept of network control of rate and propose a particular network-control method for code-division multiple access (CDMA) systems. Based on an M/M/∞//M queueing model applied to a cell under heavy traffic conditions and a new performance measure called averaged speech quality, we obtain simulation results to demonstrate how network control of rate can achieve improved speech quality or increased capacity for a given quality objective     

State- and time-dependent routing in the NTT network

The purpose of state- and time-dependent routing (STR) is to achieve high performance despite unpredictable real-time traffic fluctuations, with minimum changes to existing switching software and operations systems. STR uses an appropriate combination of the two kinds of control, centralized and distributed. The article gives an overview of STR and its advanced call-level routing, describes the current STR network and the performance of STR with two examples from the NTT network, and addresses a dimensioning method for STR     

Torsional vibrations of quartz crystal beams

An exact solution of a partial differential equation including elastic compliance constant s'₅₆, with respect to stress function ψ has been found for torsional modes of vibration of an arbitrary (singly, doubly, triply) rotated beam with a pair of parallel free edges. The solution is obtained by relaxing the condition that the edge planes are perpendicular to the main faces of the beam. That is, the edges are off perpendicular by the angle Θ=arctan(-s'₅₆ /8'₅₅). The exact solution can reduce the difference of the calculated and measured values for a thickness-to-width ratio which gives the first-order temperature coefficient α=0. Also, a comparatively large inclination of the edge cuts is required to reduce the unwanted complicated mode shapes to simple ones     

Development of a current detection type cable fault locator

A cable fault location instrument based on the detection of traveling wave currents was developed. It is different from the conventional pulse radar method based on voltage detection. Measurement is automated, and the distance to the fault point is displayed by merely pushing a switch. In a branched or crossbonded line, the fault point can be located without interference from the branched or the crossbonded point. Tests performed in both real and simulated lines confirmed the practical utility of this instrument     

High-performance polymer alloys of polybenzoxazine and bismaleimide

Two series of high-performance polymer alloys were prepared by mixing typical benzoxine monomers, 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (P-a) or 6,6-(1-methylethyliden)-bis-(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) (B-a), with a typical bismaleimide, 4,4-bismaleimidodiphenyl methane by various ratios followed by thermal treatment up to 240 °C. DSC and IR of the alloys were examined to follow the curing reaction. These analyses showed that the obtained polymer alloys are AB co-cross-linked polymer networks through the formation of ether linkage between the hydroxyl group of polybenoxazine and the double bond of bismaleimide. Viscoelastic analysis and softening temperature measurement revealed that the polymer alloys have much higher glass transition temperatures than those of each homopolymer. The thermal stability also increased with the increase of bismaleimide content as evidenced by TGA.     

Heavy arsenic doping of silicon grown by atmospheric pressure selective epitaxial chemical vapor deposition

Selective epitaxial Si with a high arsenic concentration of 2.2×10¹⁹ atoms/cm³ was deposited at a high growth rate of 3.3 nm/min under atmospheric pressure. It was confirmed that this method had excellent selectivity and produced films having good crystalline quality, abrupt dopant profiles at the interfaces, and smooth surfaces. The growth mechanism is discussed in terms of the relationship between the effects of arsenic surface segregation and etching by hydrogen chloride.     

Anterior chamber inoculation of splenocytes without Fas/Fas-ligand interaction primes for a delayed-type hypersensitivity response rather than inducing anterior chamber-associated immune deviation

The inoculation of antigens into the anterior chamber (AC) of the eye induces an antigen-specific immune response that inhibits delayed-type hypersensitivity (DTH). This regulatory response is known as anterior chamber-associated immune deviation (ACAID). The ACAID response appears to be complex, as it can be elicited by a wide variety of soluble and cell-associated antigens, including foreign, self, tumor, and alloantigens. To evaluate the contribution of Fas/Fas ligand (FasL) interaction to the induction of ACAID to alloantigens, gld and lpr mutant mice were used in conjunction with normal C3H, MRL, and BALB/c mice. ACAID was induced by inoculation of non-irradiated splenocytes from donor mice into the AC of various recipients. After 1 week, recipients were primed intradermally with donor splenocytes. One week later DTH was measured by ear swelling. C3Hgld mutants lacking functional FasL did not develop ACAID after the AC inoculation of BALB/c splenocytes. Conversely, the AC inoculation sensitized these mutants. MRL/pr mutants, which lack Fas, developed ACAID following inoculation of BALB/c cells. AC inoculation of lpr splenocytes did not induce ACAID, but sensitized C3H recipients. Treatment of the AC inoculum with an anti-Fas antibody blocked ACAID induction in a transient manner, as the recipients developed ACAID later. These results show that interaction of the Fas and FasL is required to induce ACAID to allogeneic cells. In the absence of Fas expression on donor splenocytes, or FasL expression by the recipient, AC inoculation primes for a DTH response rather than inducing ACAID.     

Bonding silicon wafer to silicon nitride with spin-on glass as adhesive

Using spin-on glass (SOG) as an adhesive, an Si wafer with thermal oxide was successfully bonded to one with an RF-sputtered Si3N4 film. This ensures that SOG films are effective in bonding Si wafers to less reactive surfaces than Si or SiO2 such as silicon nitride. It was also found that the previously reported bonding procedure can be simplified by suppressing the spin-induced radial striations of the SOG films.     

Temperature-stable low-noise ferrite memory cores

Temperature-stable low-noise memory cores made from the substituted lithium and nickel ferrites were studied. Ferrite compositions which are suitable for miniature cores have been developed by studying magnetic properties of the ferrite in the system Li-M-M' and Ni-M-M' ferrite (M:Mn, Fe, Co, Ni, Cu, and Zn). Technological approaches for fabricating small memory cores were made by studying the effect of ferrite-powder parameters and sintering conditions on magnetic properties of the substituted ferrites. Typical pulse characteristics taken with coincident current mode for cores of 0.48, 0.32, and 0.27 mm φ OD are presented. It was found that the Ni-Mn-F(II) ferrites are suitable for a low-drive high signal-to-noise ratio (dV1/dVz) temperature-stable memory core.