Achieving multimedia communications on a heterogeneous network

A heterogeneous intelligent network has been designed and implemented to allow multimedia real-time communications and messaging among local area network workstations with logically associated speakerphones and among ISDN voice/data terminals with transparent tablets on top of bitmap screens and stylus pens. The architecture, presentation, editing, storage, and retrieval of multimedia documents in these two different kinds of terminals are described. The messages and protocol conversion facilities used for multimedia communications are presented, as are the lessons learned in internetworking a local area network with ISDN     

Effects of postdetection selection diversity reception in QDPSK land mobile radio

Postdetection selection diversity reception for Nyquist pulse shaped quadrature differential PSK (QDPSK) signal transmissions is addressed. Average bit error rate (BER) performance with differential and coherent demodulation is analysed for multiple-branch diversity reception under slow multipath Rayleigh fading. Diversity effects in real fading environments are verified by 8 and 16 kbit/s transmissions at 1.45 GHz carrier frequency.<>     

Preparation of monolithic silica gel and glass by the sol-gel method using N,N-dimethylformamide

The use of N,N-dimethylformamide (DMF) was found to be effective in the sol-gel synthesis of silica gel and glass monoliths from tetramethoxysi lane (TMOS) by the sol-gel method. Wet gel bodies prepared by gelation of TMOS-DMF-CH₃OH-H₂O-NH₄OH (or HNO₃) solutions could be dried without the occurrence of fracture or cracks when drying conditions were appropriate. Furthermore, the resultant dried gel monoliths could be converted without cracking or bloating to silica glass on heating up to 1050° C and holding there for 2 h, when the composition of the starting solution was appropriate.     

Degradation of Pentoses and Hexouronic Acids in Subcritical Water

The degradation of arabinose, xylose, ribose and lyxose in subcritical water was measured at 200, 220 and 240 °C. Ribose was the most rapidly degraded among the pentoses tested. The degradation of the glucuronic and galacturonic acids proceeded at lower temperatures than that of the pentoses, and was measured at 140, 150 and 160 °C. The degradation processes of the pentoses and hexouronic acids could be expressed by the Weibull model, and the kinetic parameters were then estimated. The activation energy and frequency factor for the degradation of each substrate were estimated from the temperature dependence of the rate constant. The enthalpy‐entropy compensation held for the degradation of the pentoses as well as the hexoses, which suggests that the degradation of the hexouronic acids proceeded through a mechanism different from that for the pentoses and hexoses. The molar yield of a pentose to furfural was ca. 0.3 at any temperature, irrespective of the pentose type. Acidic compounds were also formed from the pentoses in proportion to the amount of consumed substrates. The formation of acidic compounds resulted in a rapid decrease in pH.     

Production of functional substances from black rice bran by its treatment in subcritical water

Black rice bran was treated by water and subcritical water at temperatures ranging from 20 to 260 °C for 5 min and at 200 and 260 °C for 5-120 min. The bran extracts were analyzed for their radical scavenging activity, protein and carbohydrate contents, molecular-mass distribution, antioxidation activity, emulsifying activity, and emulsion-stabilizing activity. The radical scavenging activity and the protein content of the extract were higher at higher treatment temperature. The carbohydrate content also increased with increasing temperature up to 200 °C, then steeply decreased at the temperatures higher than 200 °C. The bran extracts treated at 260 °C for 5 min exhibited a suppressive activity toward autoxidation of linoleic acid with the increasing the weight ratio of the bran extract to linoleic acid. The bran extracts prepared at 40-200 °C for 5 min showed the emulsifying- and emulsion-stabilizing activities, while the extracts prepared at 220-260 °C were low in the activities.     

Inverse scattering method for one-dimensional inhomogeneous layered media

An inverse scattering method to reconstruct simultaneously the permittivity profile and the conductivity profile of one-dimensional inhomogeneons medium which makes use of the transverse electric (TE) wave and/or transverse magnetic (TM) wave, is proposed. The medium is illuminated by the TE and/or TM plane wave at oblique incidence, and the data are taken as the reflection coefficients for a set of discrete frequencies and/or a finite number of incident angles. Furthermore, the reflection coefficient data contain the Gaussian noise. The nonlinear integral equation relating the unknown constitutive parameter of the medium to the reflection coefficient for TE wave and/or TM wave is solved by the Newton iteration method. The inverse operator in the Newton method is determined by the regularization method. It is demonstrated in terms of the numerical examples that this method utilizing both polarizations and the incident angle of the incident plane wave is very effective even if the reflection coefficient contains the practical measurement error, or the phase of the reflection coefficient is unknown. Moreover, the relationships between the errors of reconstructed profile and the measured reflection coefficient are also discussed.