Search

The article is devoted to one of the main types of quality control in production, as well as the features of control of high-pressure sodium lamps. To increase the reliability of control, it is proposed to additionally use the analysis of time series generated by the control system. We used archive data obtained by the control system as time series.

В работе отмечается, что одной из наиболее актуальных задач имитационного моделирования в области морских контейнерных перевозок является взаимодействие между собой контейнерных терминалов одного порта или нескольких портов морского побережья (морского фасада хинтерленда).По этой причине в статье рассматриваются методы оценки производительности причала, основанные на статистических данных и методе Монте-Карло, преимуществом которых является возможность оценить производительность всех операций контейнерного терминала с учетом случайного характера продолжительности отдельных движений путем наблюдения лишь за некоторыми, наиболее часто встречающимися операциями. Эти методы могут использоваться для решения задачи о взаимодействующих терминалах, когда суда осуществляют погрузо-разгрузочные операции на нескольких терминалах порта в рамках одного судозахода. Информация о производительности причала позволяет промоделировать данную систему без учета внутренних процессов контейнерного терминала. В работе доказывается, что существует зависимость между производительностью причала и размером судозахода судна. Корреляционно-регрессионный анализ позволил выявить наиболее подходящие формы зависимости линейную и степенную. В работе также получены оценки разброса выявленных зависимостей для целей имитационного моделирования. Полученная зависимость доказывает адекватность аналитических рассуждений о производительности причала, представленных в предыдущих работах.The paper notes that one of the most important tasks of simulation in the field of container shipping is the interaction of container terminals of one port or several ports of the sea coast (sea front of the hinterland) .For this reason, the article discusses methods for assessing the performance of a berth based on statistical data and Monte Carlo method, the advantage of which is the ability to evaluate the performance of all operations of the container terminal, taking into account the random nature of individual movements by monitoring only for some of the most frequently used operations. These methods can be used to solve the problem of interacting terminals when ships carry out loading and discharging operations at several port terminals within the framework of a single call. Information about the berth productivity allows to simulate this system without taking into account the internal processes of the container terminal. The paper proves that there is a relationship between the berth productivity and the size of the ships call. Correlation-regression analysis revealed the most appropriate forms of dependence - linear and power-law. The paper also obtained estimates of the spread of identified dependencies for the purpose of simulation. The obtained dependence proves the adequacy of analytical reasoning about the performance of the berth presented in previous works.

The parametric identification of nonlinear systems opens up broad prospects for the creation of modern monitoring and control systems, thereby ensuring a significant increase in their technical and economic indicators. The paper uses methods of mathematical modeling, numerical methods and the theory of neural networks. The result of the work was the proof of the possibility and acceptability of using a combination of dynamic and static neural networks for the tasks of identifying nonlinear systems. It is preferable to use a multidimensional and multilayered direct transmission network as a dynamic neural network, and a radial basis network as a static network.

The hotspot model has been used to simulate the intermediate frequency bandwidth of a lattice cooled NbN hot-electron bolometer mixer. The results of simulation suggest that with the increase of the bias current, the bandwidth decreases, passes the minimum, and recovers again. The appearance of the bandwidth minimum correlates with experimentally observed noise maximum at the mixer output that drastically reduces the sensitivity of a relevant receiver. At large bias currents the bandwidth exceeds the reciprocal electron cooling time. Since the noise temperature also increases with the bias current, a compromise between the desirable bandwidth and acceptable noise temperature can be reached by varying the bias current.

We present an analysis of a diffusion-cooled hot-electron bolometer in the limiting case of a weak thermalization of non-equilibrium quasiparticles. We propose a new model relying on the non-thermal suppression of the superconducting energy gap by excess quasiparticles. Using material parameters typical for Al, we evaluate performance of the bolometer in the heterodyne regime at terahertz frequencies. Estimates show that the mixer may have quantum limited noise temperature and a few tens of GHz bandwidth, while the required local oscillator power is in the /spl mu/W range due to in-effective suppression of the energy gap by quasiparticles with high energies.

We studied the interaction of high-frequency (HF) fields with the miniband electrons in semiconductor superlattices that show (at room temperature) negative differential conductance. We observed a field-induced reduction of current through the superlattices, with a different bias dependence for fields below and above a characteristic frequency (1 THz). An analysis based on Bloch oscillations, indicating that the electrons relaxed within one cycle of the HF field (quasistatic interaction) or followed the field adiabatically (dynamic interaction), allows one to extract the intraminiband relaxation time ${(10}^{\ensuremath{-}13}\mathrm{s}).$

Voltage and microwave photoresponse of NbN thin films to modulated and pulsed optical radiation reveals, far below the superconducting transition, a response time consistent with the lifetime of nonequilibrium quasiparticles. We show that even in 5 nm thick films at 4.2 K the phonon trapping is significant resulting in a quasiparticle lifetime of a few nanoseconds that is an order of magnitude larger than the recombination time. Values and temperature dependence of the quasiparticle lifetime obey the Bardeen-Cooper-Schrieffer theory and are in quantitative agreement with the electron-phonon relaxation rate determined from the resistive response near the superconducting transition. We discuss a positive effect of the phonon trapping on the performance of kinetic inductance detectors.

We report on a heterodyne submillimeter-wave spectrometer for laboratory studies of gases in the frequency range 280–450 GHz. The spectrometer with two backward-wave oscillators as radiation sources has been used for the measurement of transmission spectra of gaseous formic acid in the frequency range 314–317 GHz. We observed theoretically predicted absorption lines corresponding to rotational transitions of the aR(J = 13–14, ΔKa = 0) branch. We determined for the transition 133,10–143,11 the line intensity (∼ 4.6 · 10−22 cm/molecule) and the pressure broadening coefficient (10.5 MHz/Torr).

Using an autocorrelation method we studied the voltage photoresponse of a current-carrying superconducting YBa2Cu3O7−δ film excited by femtosecond near infrared radiation pulses. Near the transition temperature we found a picosecond response time consistent with the energy relaxation of nonequilibrium quasiparticles. We also observed a subpicosecond component of the voltage response which we attributed to the current redistribution between excited quasiparticles and the superconducting condensate.

We report on a superconducting hot electron bolometer coupled to radiation via a broadband antenna. The bolometer, a structured NbN film, was patterned on a thin dielectric membrane between terminals of a gold slotline antenna. We investigated the response to submillimeter radiation (wave-lengths ∼ 0.1 mm to 0.7 mm) in the fundamental Gaussian mode. We found that the directivity of the antenna was constant within a factor of 2.5 through the whole experimental range. The noise equivalent power of the bolometer at 119 µm was ∼ 3 · 10−13 W/Hz1/2; a time constant of ∼ 160 ps was estimated.

We report on the photoresponse of structured superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and NbN films to femtosecond visible light pulses. The photoresponse signals obtained at temperatures below the transition temperature consist of a positive voltage peak of 25 ps width for the YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// sample and 40 ps for the NbN sample, each limited by the temporal resolution of the different setups, followed by a longer negative voltage transient. We attribute the photoresponse signals to a nonthermal change of the kinetic inductance of the superconducting films. We also present a model describing the dynamics of nonequilibrium quasiparticles (QP) and phonons, allowing to simulate our results. Our model provides the physical background for optimization of fast detectors based on the kinetic inductance photoresponse of thin superconducting films. >

We report on the generation of far-infrared laser pulses by stimulated Raman scattering in CH3I gas. Applying a continuosly tunable high-pressure CO2 laser as pump source we obtained 38 laser lines, 35 of them new, in the spectral range from 12 to 27 cm−1. Resonantly enhanced Raman scattering occured at vibrational-rotational transitions of the ν6 fundamental as well as the 2ν3 overtone band. In our experiment the efficiency of the 2ν3 Raman transitions was found to be about three times higher than for the ν3 Raman transitions. From the temporal behavior of the CH3I Raman laser we conclude a bandwidth of about 200 MHz for the realized Raman gain region for both kinds of transitions. Our results are also discussed with respect to the properties of the other methylhalides CH3F, CH3Cl and CH3Br.

We studied the far-infrared emission characteristics of a cyclotron p-germanium laser using a broad-band superconducting Nb film detector. For magnetic fields between ∼25 kOe and ∼50 kOe, emission in a frequency range from ∼50 cm -1 to ∼100 cm -1 with maximum intensity around 90 cm -1 was obtained. We determined, for fixed magnetic fields, electric field dependences of the emission intensity taking into account that the total electric field is a sum of the applied and the Hall electric field. An analysis of the emission intensity characteristic gives evidence that transitions between the two lowest Landau levels of light holes are responsible for the laser action.

We have measured the resistance response of a current biased YBa2Cu3O7-δ thin film (thickness ∼ 700 A) at temperatures below Tc to pulsed laser radiation in a large spectral range from far-infrared waves to visible light. For generation of short pulses we used an optically pumped D2O Raman far-infrared laser and infrared high pressure CO2 laser, both delivering pulses with durations less than 500 ps, and a Nd: YAG picosecond pulse laser. We found that the responde time was less than 0.5 ns at far-infrared frequencies and increased strongly (to ∼ 4 ns) at a critical frequency of about 7 THz. The slower response is consistent with heat escape from the film while the fast response may be connected with a nonequilibrium electronic effect.

In this paper we report on the detection of new far-infrared laser lines from CH3Cl and CH3Br optically pumped with a continuously tunable high pressure CO2 laser. We found 80 new lines for CH3Cl and 9 new lines for CH3Br in the frequency region between 16 cm−1 and 41 cm−1, all due to stimulated Raman scattering. For the Raman gain regions bandwidths up to about 700 MHz were found. We also observed high intensity short far-infrared laser pulses of durations in the nanosecond regime.

Ultrafast mechanisms of radiation detection in granular YBaCuO films are studied in the wide wavelength range from millimeter waves to near infrared. With an increase in radiation frequency, the Josephson detection at the grain-boundary weak links is replaced by electron heating into the grains. This change occurs in the submillimeter wavelength range. The electron-phonon relaxation time tau /sub eph/ is determined from direct measurements, quasi-stationary electron heating measurements, and the frequency dependence of the current at which maximum voltage shift is observed. The temperature dependence of tau /sub eph/ at T

The noise temperature of a NbN phonon cooled hot-electron mixer has been measured at a frequency of 2.5 THz for various operating conditions. We obtained for optimal operation a double sideband mixer noise temperature of /spl ap/14000 K and a system conversion loss of /spl ap/23 dB at intermediate frequencies up to 1 GHz. The dependences of the mixer noise temperature on the bias voltage, local oscillator power, and intermediate frequency were consistent with the phenomenological description based on the effective temperature approximation.

Photoresponse of a superconducting film in the resistive state to pulsed radiation has been studied in the framework of a model assuming that two different effective temperatures can be assigned to the quasiparticle and phonon nonequilibrium distributions. The coupled electron-phonon-substrate system is described by a system of time-dependent energy-balance differential equations for effective temperatures. An analytical solution of the system is given and calculated voltage transients are compared with experimental photoresponse signals taking into account the radiation pulse shape and the time resolution of the readout electronics. It is supposed that a resistive state (vortices, fluxons, network of intergrain junctions, hot spots, phase slip centers) provides an ultrafast connection between electron temperature changes and changes of the film resistance and thus plays a minor role in the temporal evolution of the response. In accordance with experimental observations a two-component response was revealed from simulations. The slower component corresponds to a bolometric mechanism while the fast component is connected with the relaxation of the electron temperature. Calculated photoresponse transients are presented for different ratios of the electron and phonon specific heat, radiation pulse durations and fluences, and frequency band passes of registration electronics. From the amplitude of the bolometric component we determine the radiation energy absorbed in a film. This enables us to reveal an intrinsic electron-phonon scattering time even if it is much shorter than the time resolution of readout electronics. We analyze experimental voltage transients for NbN, ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, and ${\mathrm{TlBa}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{9}$ superconducting films and find the electron-phonon interaction times at the transition temperatures of 17, 2.5, and 1.8 ps, respectively. The values are in reasonable agreement with data of other experiments.

Photoresponse of a superconducting film in the resistive state to pulsed radiation has been simulated making use of different effective temperatures to describe electron and phonon nonequilibrium distributions. Fitting of calculated voltage transients to experimental response signals gives electron-phonon interaction times at the transition temperature 3.5 ps, and 1.8 ps for YBa 2 Cu 3 O 7 , and TlBa 2 Ca 2 Cu 3 O 9 films respectively.

We report the observation of an ultrafast photoresponse of a high-T(c), film to far-infrared radiation pulses. The response of a sample, consisting of a current-carrying structured YBa(2)Cu(3)O(7-delta) film cooled to liquid-nitrogen temperature, was studied by use of ultrashort laser pulses from an optically pumped far-infrared laser in the frequency range from 0.7 to 7 THz. We found that the response time was limited by the time resolution, 120 ps, of our electronic registration equipment.

We report what is to our knowledge the first generation of far-infrared laser radiation by stimulated Raman scattering resonantly enhanced by an overtone vibrational-rotational transition. Using a frequency-tunable high-pressure CO(2) laser as the pump source, we obtained laser emission in the frequency range from 12 to 27 cm(-1) by optical pumping of gaseous CH(3)I near resonant vibrational-rotational transitions of the 2v(3) overtone and the v(6) fundamental band. Overtone Raman transitions involving the nondegenerate v(3) vibration were found to show higher efficiency than Raman transitions within the fundamental band of the twofold-degenerated v(6) vibration. From the studies of the temporal behavior of the far-infrared laser emission, we estimate a bandwidth of approximately 200 MHz for the Raman gain regions for both the 2v(3) overtone and the v(6) fundamental transitions.