A methodological approach to the real-time software design and its use in a PCM toll office

A methodological approach to software development for real-time systems and its application to a stored-program controlled telephone exchange is described. In particular, the problems which arise from the use of a process structure to represent the switching exchange activities are discussed; the method adopted for defining the number and type of processes, the solution given to the synchronization problems and deadlock prevention are described. Moreover, the techniques adopted for decomposing the software into modules hierarchically organized are presented and their influence on system reliability and flexibility are pointed out. Lastly, the features of the adopted programming language are presented with a special reference to the choice of high-level constructs to reduce the complexity of the control paths within the programs and to facilitate the achievement of a correct cooperation among processes.     

Blood thymus hormone content in different types of neoplastic process and its changes as a result of chemotherapy and surgical removal of tumors

Levels of thymic hormones in blood serum were found to decrease during the development of Guerin's carcinoma, methylcholanthrene- and DMBA-induced carcinogenesis, soft tissue sarcomas, mammary cancer, in children with tumors of the urinary-genital tract, that evidences for the suppression of the thymic endocrine function in neoplastic processes. A decrease in the level of substances, active in the test under study is not revealed in patients with different forms of leukemias. The tumour elimination normalizes the thymic endocrine function, while multiagent chemotherapy increases the insufficiency. The data obtained suggest the immunotherapy for malignant neoplasms with thymic hormones.     

The use of pivot ratios as a guide to stability of matrix equations arising in the method of moments

In a previous communication the authors have shown that in applying the method of moments to problems in electromagnetics the matrix condition numbers can be used to indicate regions in Which instability occurs. However, the calculation of the condition numbers requires an explicit matrix inverse which is costly. The pivot ratio, which is easily calculated from information known within the Gaussian elimination scheme, indicates instabilities as well as the condition number but without requiring an explicit inverse. A number of examples illustrating the use of the pivot ratio are presented.     

Characterization of rain profiles in a second-order approximation and application to attenuation beyond 10 GHz

A new approach to characterizing the rain profile for applications involving attenuation beyond 10 GHz is presented. It is based on the use of three functionals of the rain intensity profile (referred to as "intrinsic profile parameters" because of their peculiarity of being independent of frequency) which encompasses all the relevant information contained in the profile itself with respect to the attenuation. The attenuation can then be evaluated without the need for any profile model, as happens when starting from the more usual "average rain intensity" or other similar meteorological parameters. The intrinsic parameters therefore allow for the separate accounting of the profile and the other factors affecting attenuation such as frequency, raindrop size distribution, etc. Moreover, they can be easily related to the various kinds of "effective rain intensity" and "rainy path length" defined in the literature, thus offering a tool to clean out the inherent dependence of these latter on frequency and to obtain results that are comparable among each other even though they are collected under different circumstances.     

Examining the use of YouTube as a Learning Resource in higher education: Scale development and validation of TAM model

The teaching–learning activity was a perishable service which was to be consumed as it was being delivered. It was also constrained previously by geographical location – teacher and learner being at the same place. The advent of technology has allowed some leeway for these time and space constraints. The printed books, recorded lectures, specific learning aids, etc. allow learner’s the freedom to determine the learning speed. YouTube is a content community with provision for individuals to post their own User Generated Content (UGC) for use by other users. Though, popular as an entertainment medium, it has become a valuable learning resource and is being considered as an alternative to written text hosted by different websites and blogs. However, there is no scale to measure the behavioral intentions of the users to use YouTube as a Learning Resource and no model to understand the factors influencing this behavioral intention. This paper aims at two objectives: scale development, and validating the basic Technology Acceptance Model (TAM). It defined constructs and developed scales to measure the factors explaining the behavioral intention and established the significance of relationship between different variables and the behavioral intention validating the TAM.     

Characterization of the jitter in a mode-locked Er-fiber laser and its application in photonic sampling for analog-to-digital conversion at 10 gsample/s

This paper compares two approaches for evaluating the amplitude and timing jitters of an Er-fiber laser mode-locked at 10 GHz. Using a low-noise oscillator as the clock drive for the mode-locking, relative amplitude jitter was measured as low as 0.0384% and timing jitter as low as 0.0153% (/spl Delta/f=100 Hz-40 MHz). Applying the mode-locked pulse train in a photonic sampling experiment at 10 Gsample/s, a spurious free dynamic range (SFDR) of /spl sim/48.5 dB (over the Nyquist bandwidth of 5 GHz) for multiple analog inputs at L band (1-2.6 GHz). These results correspond to an analog-to-digital conversion resolution of /spl sim/8 SFDR bits at 10 Gsample/s. Finally, the use of "instantaneous companding" is demonstrated to correct for third-order distortions generated by a Mach-Zehnder modulator used in the photonic sampling link.     

Evolution of the deformation state and composition as a result of changes in the number of quantum wells in multilayered InGaN/GaN structures

The methods of high-resolution X-ray diffraction have been used to study the multilayered structures in an In _x Ga_{1 − x} N/GaN system grown by the method of metal-organic chemical-vapor deposition. A correlation between the strain state (relaxation) of the system, the indium content within quantum wells, the ratio of the barrier/well thicknesses, and the number of quantum wells in the active superlattice is established. It is shown that partial relaxation is observed even in a structure with one quantum well. The results we obtained indicate that the relaxation processes are bound to appreciably affect the optical characteristics of devices.     

Operability diagram of drop formation and its response to temperature variation in a piezoelectric inkjet nozzle

The present study has focused on the operability diagram of drop formation and its response to temperature variation in an inkjet nozzle driven by a piezoelectric actuator. As an operating fluid, ethylene glycol was used, and square wave pulses were applied to the nozzle in the present experiments. The operability diagram was constructed in driving voltage and pulse width space by changing the operating temperature from 30 °C to 50 °C. Four distinct types of drop response have been uncovered and are summarized in the operability diagram. The four types of response include single primary drop formation, drop formation with satellites, nozzle wetting without drop formation, and emission of a random spray. From the operability diagram, W-shaped regime of single primary drop was found, which was enlarged as temperature increased. Furthermore, the time scale of the W-shaped regime is closely related to the optimal pulse width and meniscus oscillation period of the present inkjet nozzle. In addition, it was found that by increasing the driving voltage and temperature, the size of single primary drop is increased due to the reduction in viscosity and contact angle of the operating liquid.     

Floquet's theorem in three dimensions and its application to the dispersion characteristics of circular waveguides with screw periodicity for use with gyrotron backward-wave oscillators

Floquet's theorem for three dimensions is proved for each of the two mathematical conditions of periodicity: the differential equation and the boundary condition. The theorem applied to circular waveguides with screw periodicity provides the dispersion characteristics of the uncoupled modes. These characteristics are compared to those of a normal circular waveguide to show how screw periodic RF structures shift in phase the waveguide cutoff point and how such a shift is advantageous to gyrotron backward-wave oscillators.

     

Quality of service in telecommunications. I. Proposition of a QoSframework and its application to B-ISDN

The the quality of service (QoS) concept is becoming an ever more important issue in telecommunication and computer communication. The article focuses on the QoS notion and concept. The definition of QoS in the International Telecommunications Union-Telecommunications Sector (ITU-T) recommendations and the International Standards Organization (ISO) standards is analysed. Little is known about the asynchronous transfer mode (ATM) performance requirements of the broadband integrated services digital network (B-ISDN) services, especially for multimedia applications. This is because the ATM performance requirements of multimedia applications depend not only on the diverse QoS requirements from application and user, but also on the protocol stacks and scheduling in end systems. Therefore, in order to guarantee QoS to the user, it is necessary to introduce a set of QoS parameters whose properties indicate the nature and requirements of the layered protocol stack. We describe how a proposed QoS framework can be applied to B-ISDN as a specific network. The QoS aspects related to B-ISDN signaling (the control plane) and the QoS aspects related to layer and plane management (the management plane) are described. We also describe how the QoS framework resides in a protocol stack and works together with the B-ISDN network management and signaling     

扰动下一类超混沌系统的同步及其在保密通信中的应用

本文基于状态观测器方法,在扰动存在的情况下,对一类超混沌系统的同步及其在保密通信中的应用问题进行了研究。研究表明,本文所给的方法克服了扰动对系统同步所造成的影响,使得系统保持着良好的同步。另外,本文考虑的超混沌系统,对保密通信系统有着较高的保密性,因此本文的方法在实际中更加可行。     

Development and Use of the BLT Equation in the Time Domain as Applied to a Coaxial Cable

This paper discusses the use of the Baum-Liu-Tesche (BLT) equation for calculating transmission-line load responses directly in the time domain. From the frequency-domain BLT equation, its transient counterpart is first derived. For the special case of a coaxial cable, explicit expressions for the transient propagation function, the surge impedance and admittance, and the transient reflection coefficients at each end of the line are derived. These quantities, together with the transient-BLT equation, are used to compute the transient load voltages. The computed results are subsequently compared with transient responses obtained using the frequency-domain BLT equation and Fourier inversion, and the agreement is excellent for highly conducting cables. The benefit of deriving the BLT equation in the time domain is that it may be used, with slight modifications, to treat the case of nonlinear or time-varying loads. This will be described in a future paper     

A rigorous analysis of a cross waveguide to large circularwaveguide junction and its application in waveguide filter design

A rigorous analysis is obtained for the problem of scattering at the junction of a cross-shaped waveguide and a larger circular waveguide. The general case of an arbitrary offset and orientation of the cross waveguide axes is considered. The fields matching over the cross aperture of the smaller guide is facilitated by using the transformation of the circular cylindrical Bessel-Fourier modal fields of the circular guide into a finite series of exponential plane wave functions. This permits an analytical finite series solution for the elements of the fields mode matching matrix, from which the general scattering matrix of the junction is obtained. The application of the formulation to circular waveguide filter design is emphasized in the numerical examples. Excellent agreements between theoretical and experimental results are obtained in all the numerical examples     

Large scale space diversity in a widely spaced network of meteorscatter communication systems and its application to mobilecommunications

A model is developed for predicting the inherent spatial multiplexing or diversity in a widely dispersed network of meteor scatter receivers. The primary measure, network diversity, is defined as the ratio of the arrival rate of useful trails observed by the entire network to the arrival rate at an average node and is less than the number of receivers in the network. Network diversity is calculated from the ground illumination footprint of individual meteor trails and weighted by the spatial arrival pattern of trails. Predictions using the model are compared to an experiment conducted in the western US. Ramifications on the design of meteor scatter communication systems for very large network applications such as automatic vehicle location and tracking are discussed     

Anti-carcinogenic and anti-blastic effect of vitamin A in various modes of its administration to random-bred rats during carcinogenesis of the mammary gland, induced by 7,12-dimethylbenz(a)anthracene

The dependence of the anticarcinogenic and antiblastic effect of retinoid on the regime of its inoculation and on the process stage has been established using the 7,12 dimethylbenz(a)anthracene-induced mammary carcinogenesis of rats. The prophylactic administration of retinoid alone and its therapeutic inoculation against a background of hormonal correction resulted in the most expressed effect that was estimated by the elongation of the latent period, incidence and growth rate of tumours, lifespan of treated animals as well as by the distribution of malignant and benign tumours.     

大气压行波激励N_2激光器

近年来,由于高速摄影、光化学反应的研究以及荧光测量等的需要,人们希望获得超短脉冲的相干光源.行波激励的高气压N_2激光器,其光脉冲的宽度主要由受激分子的弛豫时间所决定,与光在光腔中的传播时间无关,从而成为获得微微秒脉冲紫外光源的器件之一.