Ambipolar Schottky-barrier TFTs

A novel Schottky-barrier metal-oxide-semiconductor thin-film transistor (SBTFT) was successfully demonstrated and characterized. The new SBTFT device features a field-induced-drain (FID) region, which is controlled by a metal field-plate lying on top of the passivation oxide. The FID region is sandwiched between the silicided drain and the active channel region. Carrier types and the conductivity of the transistor are controlled by the metal field-plate. The device is thus capable of ambipolar operation. Excellent ambipolar performance with on/off current ratios over 10⁶ for both p- and n-channel operations was realized simultaneously on the same device fabricated with polysilicon active layer. Moreover, the off-state leakage current shows very weak dependence on the gate-to-drain voltage difference with the FID structure. Finally, the effects of FID length are explored     

On the Estimation of the Second-Order Statistics of Log Normal Fading in Mobile Radio Environment

It is observed that the estimation of mean signal strength in the mobile radio environment has inherent uncertainties. These may not influence the observed distribution of the mean signal strength but would certainly mask efforts to obtain level crossing rates and duration of fades. A new parameter, duration of stay, is defined which appears to be insensitive to the granular variations of the mean signal strength and would be helpful in the determination of the switching rate in a base station diversity system.     

Strain-induced crystallization II. Subsequent fibrillar-to-lamellar transformation

Part II discusses numerous examples of a morphological fibrillar-to-lamellar transformation that has reportedly been observed in stretched polymers upon additional thermal treatment (or TIC), Stretched polymers containing initially a typical fibrillar morphology for either crystallites in cold-drawn polymers, crystallites induced by stretching, or simply non-crystalline fibrils can yield a more or less lamellar morphology after the thermally-induced transformation. There is no evidence of extended-chain crystals present in either the original fibrils or the transformed lamellae; however, the extent of the transformation is strongly dictated by the annealing conditions and the stretch ratios, and therefore the local strains on tie molecules between the crystallites. Of particular interest is the observation of lamellar formation in conjunction with decreasing stress (or increasing length) during TIG under strain. This is in conflict with the generally expected stress increase if chain folding is presumed to occur during formation of lamellae, Consequently, it leads to the conclusion that lamellae form from prefolded structures during TIC. In the light of this surprising conclusion, available evidence on the presence of structure or non-Gaussian chain segments in the amorphous state is also cited. Included are the most recent neutron scattering results from concentrated solutions of polystyrene.     

Polarization Diversity System for Mobile Radio

Conventional space diversity reception at typical elevated base locations requites separation of 30λ for broadside incidence and even more for in-line incidence and is therefore difficult to implement. A polarization diversity system for mobile radio is proposed. This is a two-branch receiver diversity system with the advantage that the base station antennas can be spaced as closely as desired. An experimental program has been carried out to obtain the statistical properties of vertically and horizontally polarized electromagnetic waves in a suburban environment at 836 MHz. It was observed that signals of both polarizations were Rayleigh plus log normal, where one is uncorrelated and other is correlated irrespective of base or mobile antenna spacings. The local means of the two signals were highly correlated and were with ± 3 dB for almost 90 percent of the time. Variation of base transmitter heights appeared to have little effect on the ratio of the local means of the two signals. The analysis and experiment demonstrated the feasibility of providing two diversity branches at UHF by polarization diversity.     

Calorimetric study of flammable fabrics. II. Analysis of flame retardant-treated cotton

Efficiencies of three flame retardants for cellulose, phosphoric acid, diammonium phosphate, and THPOH ammonia finish, have been evaluated based on the heat release value and the rate of heat release of treated fabrics burning in air measured with the isoperibol calorimeter. The results were compared and correlated with those obtained previously with the bomb-calorimetric technique. Complete heat balances were obtained for the systems studied by correlation of the calorimetric data and the measurement of combustible gases evolved from the fabric burning in air. The rate of heat release was found to correlate with the flame propagation rate measured at a 45° angle. The results from the heat, rate, and combustible gas measurements were interpretable in terms of existing mechanisms of flame-retardant action.     

A study on the separation efficiency of rotary thermal diffusion columns

Adjustment of the velocity profile in a concentric tube thermal diffusion column substantially increases the separation efficiency by rotating outer tube. Considerable improvement in separation was obtained by employing the rotary column instead of using the stationary column.     

Marker automata

This paper deals with finite automata augmented with markers which the automata can move about on their input tapes. The concept of augmenting markers to automata was first introduced by Blum and Hewitt [1] in two-dimensional automata. Kreider, Ritchie, and Springsteel [6, 7, 8, 12] investigated recognition of context-free languages by (one-dimensional) automata with markers. In this paper, we investigate some fundamental properties of marker automata and study their relationships to other types of automata and languages. The main result in this paper is the establishment of an infinite hierarchy of languages recognizable by deterministic and deterministic, halting marker automata. It also turns out that, because of the equivalence of finite marker automata and multi-head automata, the study of three-marker automata becomes very interesting due to results of Hartmanis [4] and Savitch [10].     

Solving boundary value problems in composite media by separation of variables and transient temperature of a reactor vessel

This paper presents the theorems of orthogonality of piecewise continous eigenfunctions. The theorems can be applied to solve boundary value problems in composite media by the method of separation of variables. Special application is made to solve the problem of transient temperature of a reactor pressure vessel during a postulated loss-of-coolant accident. The results of calculation are in good agreement with the experiments of Burck et al.     

Optimum control of a class of distributed-parameter systems

Optimum control of a class of distributed-parameter systems subject to control signal saturation is studied. The system performance is optimized with respect to an integral criterion function. This problem is solved by making use of coordinate transformation and Butkovskii's maximum principle. For this class of systems with distinct characteristic roots, the optimum control law is found to be the solution of a Fredholm integral equation of the second kind, subject to the condition of bounded signal.