Typical Delay Time Research Articles

Development of a population pharmacokinetic model of olanzapine for Chinese health volunteers and patients with schizophrenia

ObjectiveOlanzapine is an atypical antipsychotic drug commonly used for the treatment of schizophrenia. However, there are still many complications associated with the use of olanzapine, and researchers continually strive to...

An identification method for room temperature dynamic model based on analytical solution in VAV system

Variable Air Volume (VAV) system is a typical time delay system with multiple variables, and it is difficult to build a dynamic response model for describing room temperature regulation process. This paper firstly proposes a novel model of dynamic response of room temperature based on the analytical solution of heat balance equation in VAV air conditioning zone. According to the solution, inertia time constant and magnification coefficient of room temperature response can be directly calculated by initial environmental parameters. The model is further extended to a Multi-Input Single-Output (MISO) model with airflow regulating actuators as input and room temperature as model output. Experimental studies are carried out to test practical supply airflow and room temperature response and corresponding model parameters are identified according to the measured data in the VAV experimental platform. The proposed identification method based on analytical solution is validated through simulation and compared with classical identification method. Results indicate that the proposed identification method could describe the room temperature dynamic characteristics of VAV system well, and it can be applied in control simulation and engineering application in future work.

Oscillator Phase Noise Suppression in Surface Acoustic Wave Sensor Systems

Surface acoustic wave (SAW) sensors are widely used in different fields of application. In order to maximize the limit of detection of such sensor systems, it is of high importance to understand and to be able to quantify the relevant noise sources. A straightforward approach to detect the desired phase information of SAW sensors is to compare the sensor output signal with a reference signal. In this paper, the effect of decorrelation of oscillator phase noise as a function of delay time and offset frequency is discussed and analyzed. An analytical expression is derived which describes the degree of phase noise suppression in heterodyne readout systems. The model is verified by various measurement series, showing a degree of phase noise suppression of −100 dB for an offset frequency of 1 Hz and for a decorrelation time of 1500 ns which represents a typical time delay of SAW sensors. Although the effect is analyzed with respect to SAW sensors, the results are basically applicable to all kinds of phase sensitive sensors.

Research on a reduced order closed-loop identification algorithms based on AIC for process with time delay

In view of the limitations of traditional closed-loop identification methods, and considering process with time delay, a new closed-loop identification method based on Akaike’s information criterion (AIC) was proposed.it is possible to identify process model using closed-loop data under the reference signal was being excited. Firstly, the time delay term is approximated by first-order Pade and the equivalent closed-loop transfer function of closed-loop system is calculated. Secondly, the high-order discrete model which is determined by proposed method based on AIC can be obtained by the identification of the real closed-loop system. The terminal identification model which is gained from after reduction of the high-order discrete model has the same model structures as the equivalent closed-loop transfer function. Finally, solving methods of process parameters could be deduced by coefficient of same power in the two typical time delay process. Feasibility, universality, high identification accuracy and practicability of the proposed method were verified by a simulation test. It achieves satisfying identification effect in the closed-loop system identification of temperature and liquid level in distillation column reactor.

PC index as a proxy of the solar wind energy that entered into the magnetosphere: 3. Development of magnetic storms

Relationships between the 30-min smoothed PC and SymH indices in course of 430 magnetic storms observed in period of 1998–2015 have been examined. The storms were classified, by features of the PC evolution, as classic, pulsed and composite magnetic storms. It is shown these storm types are related, correspondingly, to such solar drivers as Interplanetary Coronal Mass Ejections (ICME), Stream Interaction Regions (SIR), and their joint action. Results of the statistical analysis demonstrate that depression of geomagnetic field (“Dst variation”) starts to develop as soon as PC index steadily excess the threshold level ∼1.5 mV/m, like to case of magnetic substorms. SymH index in course of magnetic storms (during 48 h preceding and succeeding the maximal depression of geomagnetic field) generally follows the time evolution of the PC index with typical delay time of ΔT ∼ 1 ± 0.5 h. The storm intensity (SymHMIN) is linearly related to maximal value of the foregoing PC index (PCMAX) observed ∼0.5÷2 h before the moment of maximal depression. The conclusion is made that the PC index can be successfully used for nowcasting the magnetic storm development.

Probing Motion of Fast Radio Burst Sources by Timing Strongly Lensed Repeaters

Abstract Given the possible repetitive nature of fast radio bursts (FRBs), their cosmological origin, and their high occurrence, detection of strongly lensed sources due to intervening galaxy lenses is possible with forthcoming radio surveys. We show that if multiple images of a repeating source are resolved with VLBI, using a method independent of lens modeling, accurate timing could reveal non-uniform motion, either physical or apparent, of the emission spot. This can probe the physical nature of FRBs and their surrounding environments, constraining scenarios including orbital motion around a stellar companion if FRBs require a compact star in a special system, and jet-medium interactions for which the location of the emission spot may randomly vary. The high timing precision possible for FRBs (∼ms) compared with the typical time delays between images in galaxy lensing (≳10 days) enables the measurement of tiny fractional changes in the delays ( ) and hence the detection of time-delay variations induced by relative motions between the source, the lens, and the Earth. We show that uniform cosmic peculiar velocities only cause the delay time to drift linearly, and that the effect from the Earth’s orbital motion can be accurately subtracted, thus enabling a search for non-trivial source motion. For a timing accuracy of ∼1 ms and a repetition rate (of detected bursts) of ∼0.05 per day of a single FRB source, non-uniform displacement ≳0.1–1 au of the emission spot perpendicular to the line of sight is detectable if repetitions are seen over a period of hundreds of days.

On the three explosion limits of an H2–O2 system and their relationships to ignition delay

We propose a unified model for the three branches of the explosion limits of an H2–O2 mixture. By using different expressions for the ignition delay time at each limit, and by utilizing the Le-Chatelier rule, we obtain an analytical expression for the ignition delay time of the mixture. We show that by solving the time delay equation for a selected typical ignition delay time we obtain a single expression for the Z-shape explosion limits.

The ionospheric storms in the American sector and their longitudinal dependence at the northern middle latitudes

On the basis of the total electron content (TEC) observations from Madrigal database, we have made a statistical analysis of the ionospheric response during 217 geomagnetic storms from the year 2001 to 2015, including observations at 6 different latitude zones along one meridian in the American sector and 4 different longitudes at the middle latitude zone. Our results show that the ionospheric storm has prominent latitudinal dependence, with negative storm prevailing at high latitudes and positive storm at lower latitudes. The maximum ratio of positive to negative storms is observed at around 30°N magnetic latitude. The ionospheric response depends also on the phases of the storm. The occurrence of positive storm decreases during recovery phase when compared to that during main phase, while the negative storm presents opposite pattern. However, the occurrence of positive storm increases at equatorial and low latitudes during recovery phase. Additionally, during main phase, the occurrence of negative storm is higher at equatorial and low latitudes than that at middle latitudes. The local time dependences of the ionospheric storm onsets are quite different for different latitudes. The negative storm mainly occurs from post-middle night to morning hours and the positive storm mainly occurs during daytime at middle latitudes; while both the positive and negative storms mainly occur during nighttime at equatorial latitude. For all latitudes, the typical time delay between the main phase onset and the onset time of ionospheric negative storm is longer than 10h, while it is shorter than 10h for positive storm (expect at low and equatorial latitudes). We further check the longitudinal dependence of the ionospheric storm at middle latitude, and find that the occurrence of positive storm is higher in American and Asian sectors than that in European sector, and the non-significant storm is mostly observed in European sector. The ‘forbidden time interval’ of negative storm in Asian sector is different with that in American and European sectors.

Lensing of Fast Radio Bursts as a Probe of Compact Dark Matter.

The possibility that part of the dark matter is made of massive compact halo objects (MACHOs) remains poorly constrained over a wide range of masses, and especially in the 20-100 M_{⊙} window. We show that strong gravitational lensing of extragalactic fast radio bursts (FRBs) by MACHOs of masses larger than ∼20 M_{⊙} would result in repeated FRBs with an observable time delay. Strong lensing of a FRB by a lens of mass M_{L} induces two images, separated by a typical time delay ∼few×(M_{L}/30 M_{⊙}) msec. Considering the expected FRB detection rate by upcoming experiments, such as canadian hydrogen intensity mapping experiment (CHIME), of 10^{4} FRBs per year, we should observe from tens to hundreds of repeated bursts yearly, if MACHOs in this window make up all the dark matter. A null search for echoes with just 10^{4} FRBs would constrain the fraction f_{DM} of dark matter in MACHOs to f_{DM}≲0.08 for M_{L}≳20 M_{⊙}.

The rate, luminosity function and time delay of non-Collapsar short GRBs

We estimate the rate and the luminosity function of short (hard) Gamma-Ray Bursts (sGRBs) that are non-Collapsars, using the peak fluxes and redshifts of BATSE, Swift and Fermi GRBs. Following Bromberg2013 we select a sub-sample of Swift bursts which are most likely non-Collapsars. We find that these sGRBs are delayed relative to the global star formation rate (SFR) with a typical delay time of a 3-4 Gyr (depending on the SFR model). However, if two or three sGRB at high redshifts have been missed because of selection effects, a distribution of delay times of ~1/t would be also compatible. The current event rate of these non-Collapsar sGRBs with L_iso > 5*10^49 erg/s is 4.1(-1.9,+2.3)Gpc^-3 yr^-1. The rate was significantly larger around z ~ 1 and it declines since that time. The luminosity function we find is a broken power law with a break at 2.0(-0.4,+1.4) * 10^52~erg/s and power-law indices 0.95(-0.12,+0.12) and 2.0(-0.8,+1.0). When considering the whole Swift sGRB sample we find that it is composed of two populations: One group (~ 60%-80% of Swift sGRBs) with the above rate and time delay and a second group (~ 20%-40% of Swift sGRBs) of potential "impostors" that follow the SFR with no delay. These two populations are in very good agreement with the division of sGRBs to non-Collapsars and Collapsars suggested recently by Bromberg2013. If non-Collapsar sGRBs arise from neutron star merger this rate suggest a detection rate of 3-100 yr^-1 by a future gravitational wave detectors (e.g. Advanced Ligo/Virgo with detection horizon on 300 Mpc), and a co-detection with Fermi (Swift) rate of 0.1-1 yr^-1 (0.02-0.14 yr^-1). We estimate that about 4 * 10^5 (f_b^-1 / 30) mergers took place in the Milky Way. If $0.025 m_\odot$ were ejected in each event this would have been sufficient to produce all the heavy r-process material in the Galaxy.

Integrated photonic reservoir computing based on hierarchical time-multiplexing structure.

An integrated photonic reservoir computing (RC) based on hierarchical time-multiplexing structure is proposed by numerical simulations. A micro-ring array (MRA) is employed as a typical time delay implementation of RC. At the output port of the MRA, a secondary time-multiplexing is achieved by multi-mode interference (MMI) splitter and delay line array. This hierarchical time-multiplexing structure can ensure a large reservoir size with fast processing speed. Simulation results indicate that the proposed RC system yields better performance than previously reported ones. The achieved normalized mean square error between the system output and target sequence are 0.5% and 2.7% for signal classification and chaotic time series prediction, respectively, while the sample rate is as high as 1.3 Gbps.

Upgrade of the CMD-3 TOF system

The upgrade of the CMD-3 Time of Flight system (TOF) based on strip scintillation counters is described. The TOF is located inside 7 mm gap between LXe and CsI barrelcalorimeters. The principal objective of this system is to identifyslow antineutrons produced in the reaction e+e−→nn̄.Due to low velocities these antineutrons annihilate in calorimetersand have a typical delay time about 4-10 ns with respect to the beamcrossing in VEPP-2000 e+e− collider. The signals coming from stripscintillation counters are readout by two SiPM on both sides of thestrip. Time resolution is measured with cosmic rays and is ∼ 1ns.

THE BIRTH RATE OF SNe Ia FROM HYBRID CONe WHITE DWARFS

Considering the uncertainties of the C-burning rate (CBR) and the treatment of convective boundaries, Chen et al. (2014) found that there is a regime where it is possible to form hybrid CONe white dwarfs (WDs), i.e. ONe WDs with carbon-rich cores. As these hybrid WDs can be as massive as 1.30 $M_{\odot}$, not much mass needs to be accreted for these objects to reach the Chandrasekhar limit and to explode as Type Ia supernovae (SNe Ia). We have investigated their contribution to the overall SN Ia birth rate and found that such SNe Ia tend to be relatively young with typical time delays between 0.1 and 1 Gyr, where some may be as young as 30 Myr. SNe Ia from hybrid CONe WDs may contribute several percent to all SNe Ia, depending on the common-envelope ejection efficiency and the CBR. We suggest that these SNe Ia may produce part of the 2002cx-like SN Ia class.

STRONG GRAVITATIONAL LENSING AS A TOOL TO INVESTIGATE THE STRUCTURE OF JETS AT HIGH ENERGIES

The components of blazar jets that emit radiation span a factor of $10^{10}$ in scale. The spatial structure of these emitting regions depends on the observed energy. Photons emitted at different sites cross the lens plane at different distances from the mass-weighted center of the lens. Thus there are differences in magnification ratios and time delays between the images of lensed blazars observed at different energies. When the lens structure and redshift are known from optical observations, these constraints can elucidate the structure of the source at high energies. At these energies, current technology is inadequate to resolve these sources and the observed light curve is thus the sum of the images. Durations of $\gamma$-ray flares are short compared with typical time delays; thus both the magnification ratio and the time delay can be measured for the delayed counterparts. These measurements are a basis for localizing the emitting region along the jet. To demonstrate the power of strong gravitational lensing, we build a toy model based on the best studied and the nearest relativistic jet M87.

High-pressure low-temperature ignition behavior of syngas mixtures

Ignition properties of simulated syngas mixtures were systematically investigated at high-pressure low-temperature conditions relevant to gas turbine combustor operation using the University of Michigan Rapid Compression Facility. Pressure time history measurements and high-speed imaging of the ignition process in this facility were used to determine auto-ignition delay times and observe and characterize ignition behaviors. The simulated syngas mixtures were composed of H2 and CO with a molar ratio of 0.7, for equivalence ratios (φ) of 0.1 and 0.5, near air dilution (i.e. molar O2 to inert gas ratio of 1:3.76), with N2 as the primary diluent gas. The pressures and temperatures after compression ranged from 3–15atm and 870–1150K respectively. The comprehensive results of the present work combined with those from previous shocktube studies in the literature clearly illustrate the existence of both homogeneous and inhomogeneous auto-ignition behaviors at these conditions. Analysis of patterns in the ignition behaviors revealed a dependence on temperature, pressure, and equivalence ratio with distinct thermodynamic regions in which the ignition behavior is consistent and repeatable. Predicted locations of the strong ignition limit made using a criterion which compares laminar flame speed to a thermal gradient driven front propagation speed have excellent agreement with the experimental findings for each φ and an assumed gradient of 5K/mm. Experimental validation of this unique and powerful criterion means that it can be used for a priori prediction of the strong ignition limit using basic computational simulations. The validity of this criterion is fundamentally important, quantitatively describing the roles of chemical kinetics, thermo-physical properties, and device dependent thermal characteristics in determining auto-ignition behavior. Additionally, a comparison of the measured auto-ignition delay times to predictions made using zero-dimensional homogeneous reactor modeling revealed that agreement was dependent on φ, with excellent agreement for φ=0.1 and large discrepancies for φ=0.5. These results indicate that while inhomogeneous ignition phenomena are not entirely avoidable by reducing equivalence ratio, the subsequent effects on the accuracy of typical auto-ignition delay time predictions may be reduced or eliminated.

A High-Precision and Low-Cost Planar Array Signal Simulator Based on Cable Delays

For common planar array in Global Navigation Satellite System (GNSS) receivers, effective array signal simulation requires high-precision control of time delays and is very sensitive to errors. Typical array time delay range is about 0 ~ 0.6 ns. The resolution and accuracy needed for time delay controlling is within 0.005 ns. Such rigorous specifications make array simulation quite difficult. Common techniques always need the collaboration of a large number of hardware equipments, which are costly and complicated and therefore limited to widespread applications. This letter presents a planar array signal simulator based on cable delays, which is less expensive, easy to implement, and high-precision. However, electromagnetic waves propagate at a relatively lower velocity in transmission lines than in air, which may result in large errors and problems in designing of the array wavefront simulator. In this letter, the velocity difference and its influence mechanism on array simulator design were analyzed deeply. On this basis, errors introduced by propagation velocity difference were calibrated, which effectively improved the accuracy of array signal simulators based on cable delays. Experimental results show that the direction-of-arrival (DOA) simulation accuracy is better than 5 °. The technique can be utilized in the research of adaptive antenna array anti-interference algorithm.

Short-Term Facilitation may Stabilize Parametric Working Memory Trace

Networks with continuous set of attractors are considered to be a paradigmatic model for parametric working memory (WM), but require fine tuning of connections and are thus structurally unstable. Here we analyzed the network with ring attractor, where connections are not perfectly tuned and the activity state therefore drifts in the absence of the stabilizing stimulus. We derive an analytical expression for the drift dynamics and conclude that the network cannot function as WM for a period of several seconds, a typical delay time in monkey memory experiments. We propose that short-term synaptic facilitation in recurrent connections significantly improves the robustness of the model by slowing down the drift of activity bump. Extending the calculation of the drift velocity to network with synaptic facilitation, we conclude that facilitation can slow down the drift by a large factor, rendering the network suitable as a model of WM.

THE STELLAR AGES AND MASSES OF SHORT GAMMA-RAY BURST HOST GALAXIES: INVESTIGATING THE PROGENITOR DELAY TIME DISTRIBUTION AND THE ROLE OF MASS AND STAR FORMATION IN THE SHORT GAMMA-RAY BURST RATE

[Abridged] We present optical and NIR observations of 19 short GRB host galaxies, aimed at measuring their stellar masses and population ages. The goals of this study are to evaluate whether short GRBs track the stellar mass distribution of galaxies, to investigate the progenitor delay time distribution, and to explore any connection between long and short GRB progenitors. Using single stellar population models we infer masses of log(M/M_sun)=8.8-11.6 and population ages of tau=0.03-4.4 Gyr. We further infer maximal masses of log(M/M_sun)=9.7-11.9 by assuming stellar population ages equal to the age of the universe at each host's redshift. Comparing the distribution of stellar masses to the general galaxy mass function we find that short GRBs track the cosmic stellar mass distribution only if the late-type hosts generally have maximal masses. However, there is an apparent dearth of early-type hosts compared to the equal contribution of early- and late-type galaxies to the cosmic stellar mass budget. These results suggest that stellar mass may not be the sole parameter controlling the short GRB rate, and raise the possibility of a two-component model with both mass and star formation playing a role. If short GRBs in late-type galaxies indeed track the star formation activity, the resulting typical delay time is ~0.2 Gyr, while those in early-type hosts have a typical delay of ~3 Gyr. Using the same stellar population models we fit the data for 22 long GRB hosts and find that they have lower masses and younger population ages, with <log(M/M_sun)>=9.1 and <tau>=0.06 Gyr, respectively; their maximal masses are similarly lower, <log(M/M_sun)>=9.6. Most importantly, the two host populations remain distinct even if we consider only the star-forming hosts of short GRBs, supporting our previous findings that the progenitors of long GRBs and short GRBs in late-type galaxies are distinct.

宇宙線と雲形成―フォーブッシュ現象で雲は減るか？―

Possible influences of cosmic rays on terrestrial climate have been studied by many researchers since a good correlation between neutron monitor counts and global cloud amount was reported by Svensmark and Friis-Christensen in 1997. The cosmic ray-cloud relationship may be best tested during Forbush decrease events, in which cosmic rays largely decrease for several days associated with coronal mass ejections. Some cloud parameters are likely to respond to the transient decrease of cosmic rays with a typical time delay of several days, although we do not know the physics behind the cosmic-ray cloud relationship.

Patterns of seismic sequences in the Levant—interpretation of historical seismicity

There are historical accounts of about a hundred damaging earthquakes that occurred during the last two millennia in the Levant, in and around the Dead Sea fault system, and about half of which were associated with additional felt shocks. Several modes of earthquake sequences can be distinguished in them: (a) In 46 accounts, only one single event is noted. These are not known from tectonic settings similar to that of the Levant, and may just be a result of incomplete reporting. (b) In four cases, quakes preceded the mainshock by minutes, hours, and up to several weeks—possibly foreshocks. (c) Thirty-five mainshock–aftershock sequences were noted, lasting hours, days, weeks, months, and even more than a year; four of these also have foreshocks. No typical delay time was recognized for the largest or most significant aftershocks: they appeared up to several months later. (d) Six of the reported mainshock–aftershock sequences appeared in a “storm.” Another 13 sequences are insufficient to specify further.