Time Response Characteristics Research Articles

Application of time-resolved shadowgraph imaging and computer analysis to study micrometer-scale response of superfluid helium.

Application of inexpensive light emitting diodes as backlight sources for time-resolved shadowgraph imaging is demonstrated. The two light sources tested are able to produce light pulse sequences in the nanosecond and microsecond time regimes. After determining their time response characteristics, the diodes were applied to study the gas bubble formation around laser-heated copper nanoparticles in superfluid helium at 1.7 K and to determine the local cavitation bubble dynamics around fast moving metal micro-particles in the liquid. A convolutional neural network algorithm for analyzing the shadowgraph images by a computer is presented and the method is validated against the results from manual image analysis. The second application employed the red-green-blue light emitting diode source that produces light pulse sequences of the individual colors such that three separate shadowgraph frames can be recorded onto the color pixels of a charge-coupled device camera. Such an image sequence can be used to determine the moving object geometry, local velocity, and acceleration/deceleration. These data can be used to calculate, for example, the instantaneous Reynolds number for the liquid flow around the particle. Although specifically demonstrated for superfluid helium, the technique can be used to study the dynamic response of any medium that exhibits spatial variations in the index of refraction.

Hierarchical Voltage Control of Weak Subtransmission Networks With High Penetration of Wind Power

In this paper, we propose a novel coordinated control framework to handle negative voltage impacts caused by wind power in a weak subtransmission system. The designed controller addresses the problem of optimal coordination of controls with different response time and control characteristics. In our control design, the traditional voltage regulators (TVRs) such as on-load tap changers and capacitors are primarily used to regulate voltages in the network. If the control actions of TVRs cannot meet the control requirements, an event-triggered load-side aggregate controller will be activated immediately to help regulate voltages. The control schedules of TVRs are calculated through a multitime-step optimization-based model-predictive control method and are updated with the help of wind power predictions. The load-side controller is realized by controlling active power consumptions of load aggregators through an optimal distributed algorithm that relies on local information exchanges between neighboring load aggregators. The effectiveness of the proposed control scheme is tested through a case study on a modified IEEE 30-bus test system with high penetration of wind power.

E-health-IoT Universe: A Review

The Internet of Things (IoT) devices are able to collect and share data directly with other devices through the cloud environment, providing a huge amount of information to be gathered, stored and analyzed for data-analytics processes. The scenarios in which the IoT devices may be useful are amazing varying, from automotive, to industrial automation or remote monitoring of domestic environment. Furthermore, has been proved that healthcare applications represent an important field of interest for IoT devices, due to the capability of improving the access to care, reducing the cost of healthcare and most importantly increasing the quality of life of the patients. In this paper, we analyze the state-of-art of IoT in medical environment, illustrating an extended range of IoT-driven healthcare applications that, however, still need innovative and high technology-based solutions to be considered ready to market. In particular, problems regarding characteristics of response-time and precision will be examined. Furthermore, wearable and energy saving properties will be investigated in this paper and also the IT architectures able to ensure security and privacy during the all data-transmission process. Finally, considerations about data mining applications, such as risks prediction, classification and clustering will be provided, that are considered fundamental issues to ensure the accuracy of the care processes.

Studies on inter-dependency of electrooptic characteristics of orange azo and blue anthraquinone dichroic dye doped polymer dispersed liquid crystals

The optical properties of dyes dissolved in polymer dispersed liquid crystals (PDLCs) typically required fulfilling their absorption properties, degree of alignment and stability for practical applications. Reported herein is the absorption and electro optic behaviour of dye doped PDLCs prepared by equal weight ratio of nematic liquid crystal (LC) and photo-curable polymer (NOA 65) with different weight concentrations (0.0312, 0.0625, 0.1248, and 0.2494%) of azo and anthraquinone dyes. Considering Beer's law, OFF state absorption coefficients were measured followed by dyes' extinction coefficients. Higher absorption coefficient of azo dye doped PDLCs with dye concentrations (0.1248 and 0.2494%) resulted in superior contrast ratio (CR) as compared with anthraquinone dye doped PDLCs. However, at lower concentrations (0.0312 and 0.0625%) of anthraquinone dye, ON state transmittance of dye doped PDLCs is more dominating which resulted in higher CR at these concentrations. The experimental results were found be consistent with the theoretical results. In addition, inter-dependency among transmission, absorption coefficient, CR, applied voltage and response time characteristics of azo and anthraquinone dye doped PDLCs have been discussed and analyzed.

Cooling power and characteristic times of composite heatsinks and insulants

Thermal energy storage materials for transient thermal management applications must exhibit large energy storage densities as well as large cooling/heating power densities. The latter property has proven difficult to quantify on a materials basis because it depends on extrinsic effects. Here, we apply a previously defined cooling power figure of merit, a measure of a material’s intrinsic capacity to absorb a transient heat pulse, to analyze composite phase change material heatsinks and insulants. The results demonstrate important limits on the effects of high- and low-conductivity component volume fractions, orientations, and the critical lengthscales of individual components. Champion composites are predicted to have up to 5 times greater figure of merit than pure high-conductivity materials and up to 30 times greater figure of merit than pure phase change materials. Furthermore, composites consisting of insulating materials containing dispersed phase change materials are predicted to exhibit an order of magnitude increase in their characteristic response time. These results demonstrate the utility of the cooling power figure of merit to design compact high power and energy density heatsink and insulant materials.

Сценарий управления сетью операторского класса Carrier Ethernet и оценка длительности цикла управления

Objective: To develop a formalized algorithm of carrier class network Carrier Ethernet operation and, by means of the latter, obtain an assessment of control cycle duration for intelligent control system (ISU) of the network in question. The given operation scenario is different from those currently in use by an account of processes of the new generation Carrier Ethernet network, failures’ identification and reconstruction of network elements by means of core control technologies of elements’ status (OAM technologies) and application of statistically defined change traffic (distributive laws) of Carrier Ethernet network elements’ status. Methods: In order to achieve the objective in question the following methods were applied: signature method, statistical method and neural networks. Results: The building principles of Carrier Ethernet network were presented and its OAM architecture was formed. In accordance with the analyzed types of Carrier Ethernet network connections and failure control mechanisms on the basis of OAM, control process and Carrier Ethernet network operation scenario was developed. Practical importance: The obtained operation scenario of the new generation network and the assessment of ISU control cycle of Carrier Ethernet network makes it possible to formulate the requirements to perspective operation system, whereas the assessment result of Carrier Ethernet network operation cycle duration allows one to determine probabilistically time response characteristics of network functioning and assess the input of different subprocesses in the total process time. The presented building principles of Carrier Ethernet network make it possible to solve the task halfway, which is aimed at the necessity of building a unified methodological basis for the formation of perspective operation system for the network in question.

Vanadium, rhodium, silver and cobalt self-powered neutron detector calculations by RAST-K v2.0

Vanadium, rhodium, silver and cobalt Self-Powered Neutron Detectors (SPNDs) are evaluated and compared in this study, including their characteristic response time. The module for response calculations of different SPNDs has been programmed and added to RAST-K v2.0 (Reactor Analysis code for Steady-state and Transient). For simplification purposes and running time minimization, previously studies have often adopted the simplified depletion chain of the SPNDs. The isomers are often neglected in the detectors studies because of their low levels of contribution to the final signal. Besides, few published documents can be found for comparisons of the behavior of different emitters in normal power changes, especially for silver and cobalt emitters. In this paper, the full depletion chains for different emitters are adopted, and the isomers’ contributions are calculated. A new method for detector response calculation based on Chebyshev Rational Approximation Method (CRAM) is used as the depletion method. It is shown that the response of silver SPND is very similar to that of rhodium SPND and can be considered as an alternate emitter material for light water reactors. This study can contribute to the selection of proper SPNDs in specific applications.

Dynamics of overall swelling profile of multiresponsive ionic dimethylacrylamide-based hydrogels and cryogels: Diffusion characteristics evaluation of salt-dependent swelling

ABSTRACTDue to the importance of ion–polymer interactions in many technological applications, systematic measurements have been investigated on a variety of ionic poly(N,N-dimethylacrylamide) (PDMAAm) hydrogels and cryogels to determine the effect of mono- and multivalent ions on their dynamic properties. Using uniaxial compression, the influence of counter-ion valency on flexibility of charged polymer chains was investigated and the results were discussed as a function of ionic comonomer. To estimate the general swelling features, diffusion process and oscillating swelling–deswelling kinetics of ionic PDMAAm gels in salt solutions have been explained by model equations using early-time approximation as a function of characteristic response time.

On the kinematics and dynamics of crystal‐rich systems

AbstractPartially molten rocks, often called a mush, are examples of a hydrogranular mixture where the dynamics are controlled by both fluid and crystal‐crystal interactions. An obstacle to progress in understanding high‐temperature hydrogranular systems has been the lack of adequate levels of description of microphysical processes. Here we rationalize the hydrogranular kinematic and dynamic states by applying the concept of particle (crystal) force chains. We exemplify this with discrete‐element computational fluid dynamic simulations of the intrusion of a basaltic melt into an olivine‐basalt mush, where crystal‐scale force chains, crystal transport, and melt mixing are resolved. To describe the microscale kinematics of the system, we introduce the coordination number and the fabric tensors of particle contacts and forces. We quantify the changing contact and force fabric anisotropy, coaxiality, and the connectedness of the mush, under dynamic conditions. To describe the dynamics, particle and fluid characteristic response times are derived. These are used to define local and bulk Stokes numbers, and viscous and inertia numbers, which quantify the multiphase coupling under crystal‐rich conditions. We employ the Sommerfeld number, which describes the importance of crystal‐melt lubrication, with a viscous number to illustrate the dynamic regimes of crystal‐rich magmas. We show that the notion of mechanical “lock up” is not uniquely identified with a particular crystal volume fraction and that distinct mechanical behaviors can emerge simultaneously within a crystal‐rich system. We also posit that this framework describes magmatic fabrics and processes which “unlock” a crystal mush prior to eruption or mixing.

A novel technique to design cuckoo search based FOPID controller for AVR in power systems

Firstly, this paper develops a robust fractional order proportional integral derivative (FOPID) controller for automatic voltage regulator (AVR) in power systems. In the proposed controller, optimum design parameters, such as, proportional, integral, derivative gains, integral and derivative constants, have been achieved by using cuckoo search (CS) algorithm. Then, the time response characteristics of AVR with and without proposed controller have been investigated to reveal the effectiveness of the proposed controller. Also, the performance of the proposed controller has been tested under the condition of the parameter uncertainty and improved performance has been revealed. Finally, the accuracy and robustness of the proposed controller has been investigated through the comparative analysis of the results, achieved from proposed and other existing controllers using the same sets of data. It is shown that the proposed controller provides the better time response characteristics than the other existing techniques.

Design and Fabrication of a Novel Stimulus-Feedback Anticorrosion Coating Featured by Rapid Self-Healing Functionality for the Protection of Magnesium Alloy.

Corrosion potential stimulus-responsive smart nanocontainers (CP-SNCs) are designed and synthesized based on the installation of the supramolecular assemblies (bipyridinium ⊂ water-soluble pillar[5]arenes) onto the exterior surface of magnetic nanovehicles (Fe3O4@mSiO2), linked by disulfide linkers. The supramolecular assemblies with high binding affinity as gatekeepers effectively block the encapsulated organic corrosion inhibitor, 8-hydroxyquinoline (8-HQ), within the mesopores of Fe3O4@mSiO2. When the corrosion potential of the magnesium alloy (-1.5 V vs SHE) is exerted, 8-HQ is released instantly because of the cleavage of disulfide linkers and the removal of the supramolecular assemblies. CP-SNCs were incorporated into the hybrid organic-inorganic sol-gel coating to construct a corrosion potential stimulus-feedback anticorrosion coating (CP-SFAC) that was then deposited on the magnesium alloy, AZ31B. With the aid of a magnetic field, CP-SNCs were gathered in the proximity of the surface of AZ31B. CP-SFAC showed a satisfactory anticorrosion performance, more importantly, through the evaluation of microzone electrochemical techniques. CP-SFAC presented the rapid self-healing functionality when the localized corrosion occurred. Shortening the distance between CP-SNCs and the surface of AZ31B enhances the availability of the incorporated CP-SNCs and makes most of the CP-SNCs to timely respond to the corrosion potential stimulus and facilitates the formation of a compact molecular protective film before the corrosion products pile up. The characteristics of fast response time and quick self-healing rate meet the requirements of the magnesium alloy for self-healing in local regions.

Sensing characteristics of nanocrystalline bismuth oxide clad-modified fiber optic gas sensor

Gas sensing properties of nanocrystalline bismuth oxide clad – modified fiber optic sensor is reported for ammonia, ethanol, methanol and acetone gasses at room temperature. The output of sensor increases or decreases for certain gasses when the concentration of the gas is increased. The sensor exhibits high response and good selectivity to methanol gas. Time response characteristics of the sensor are also reported.

GPU acceleration of absolute EIT image reconstruction using simulated annealing

Electrical impedance tomography (EIT) is a portable low-cost medical image technique with fast time response characteristics. EIT can be approached as an optimization problem whose objective is to minimize the difference between the simulated and measured distributions. A preconditioned conjugated gradient is employed to solve a linear system with a symmetric sparse positive definite matrix. In order to increase its efficiency, a matrix format, the colored padded jagged diagonals storage (pJDS) format, is proposed. Parallelization is applied to several steps of the algorithm and at each step performance is observed to be superior to fast serial implementation. However, API overhead degraded the performance of the forward problem. Kernel consolidation combined with the pJDS format obtained a significant performance improvement. The inverse problem is solved as an optimization problem using the simulated annealing with adaptive neighborhood. While several instances of the conjugated gradients run on the GPU, the remaining processes are executed in parallel in the CPU. The GPU saturates at a speedup of 5 times as compared to CPU processing.

超微細なパルス射出に対する嗅覚の時間応答特性と時間分解能の測定( 香り・人・システム)

超微細なパルス射出に対する嗅覚の時間応答特性と時間分解能の測定( 香り・人・システム)

Сравнение эффективности работы точных и приближенных алгоритмов для решения задачи о покрытии множества

Introduction. A quite general class of practical tasks is guided by the set covering problem: schedules building, layout of service stations, and creation of electronic circuits. It defines relevance of searching methods to improve the solution efficiency of this task. Materials and Methods. Techniques of the set covering problem solution by exact and approximate algorithms are considered. The genetic algorithm is used as the approximate method, and the branch and bounds algorithm - as the exact method. Research Results. The genetic algorithm in all its modifications on time response characteristics has shown predictability and stability in all series of experiments. The branch and bounds method was applied to the set covering task, and it has shown exact results. Discussion and Conclusions . The conducted research shows that for small sets, it is expedient to use the branch and bounds method which has demonstrated fast runtime with an assured exact result. For large sets, it is recommended to use the genetic algorithm which guarantees receiving a result with a negligible error where the execution time shift is stable and predictable.

Centennial glacier retreat as categorical evidence of regional climate change

The near-global retreat of glaciers over the last century provides some of the most iconic imagery for communicating the reality of anthropogenic climate change to the public. Surprisingly, however, there has not been a quantitative foundation for attributing the retreats to climate change, except in the global aggregate. This gap, between public perception and scientific basis, is due to uncertainties in numerical modelling and the short length of glacier mass-balance records. Here we present a method for assessing individual glacier change based on the signal-to-noise ratio, a robust metric that is insensitive to uncertainties in glacier dynamics. Using only meteorological and glacier observations, and the characteristic decadal response time of glaciers, we demonstrate that observed retreats of individual glaciers represent some of the highest signal-to-noise ratios of climate change yet documented. Therefore, in many places, the centennial-scale retreat of the local glaciers does indeed constitute categorical evidence of climate change. Glaciers have been retreating almost globally over the past century. An analysis using signal-to-noise ratio as a metric of individual glacier change reveals that glacier retreat constitutes categorical evidence for regional climate change.

Response Time Characteristics of the Fast-2D Optical Array Probe Detector Board

AbstractTwo-dimensional optical array probes are commonly used for imaging raindrops and ice particles on research aircraft. The ability of these probes to accurately measure particle concentration and size partly depends on the response characteristics of the detection system. If the response characteristics are too slow, then small particles are less likely to be detected and the associated effective sample volume decreases. In an effort to better understand the sample volumes of optical array probes at the National Center for Atmospheric Research, the temporal response of the Fast-2D optical array probe detector board from optical input on the detector to digitization was characterized. The analysis suggests that the board electronics have a response time constant consistently near 50 ns. However, there is also a slow decay term that conforms to a decay rate. The amplitude of this slow function can impact the probe response, varying the minimum detectable pulse width between 60 and 150 ns. Also, the amplitude of the slow function is largely dictated by the illumination angle of incidence. The effects of the response time characteristics are analyzed using a simulator for a 2D cloud (2D-C) probe with 25-μm photodiode spacing. The results show the greatest sensitivity to response time characteristics when particles are smaller than 150 μm, where 10% uncertainty in the slow fraction is likely to produce sample volume uncertainties near 10%. Ignoring response time effects may bias sample volume estimates in the small size regime by as much as 25%.

Gas sensing based on detection of light radiation from a region of modified cladding (nanocrystalline ZnO) of an optical fiber

A new type of fiber optic gas sensor is proposed by detecting a light radiated from a region of cladding modified with metal oxide (nanocrystalline ZnO). The intensity of radiated light is found to vary with different gasses and concentrations. Sensing characteristics are studied for ammonia, methanol, ethanol and acetone gasses. Gas sensitivity of the proposed sensor is compared with clad-modified fiber optic gas sensor. The new sensor exhibits enhanced sensitivity. Time response characteristics of the sensor are reported.

층류제트유동 불안정성에 미치는 교류 전기장 효과

The effect of applied electric fields on jet flow instability was investigated experimentally by varying the direct current (DC) voltage and the alternating current (AC) frequency and voltage applied to a jet nozzle. We aimed to elucidate the origin of the occurrence of twin-lifted jet flames in laminar jet flow configuration, which occur when AC electric fields are applied. The results indicate that a twin-lifted jet flames originates from cold jet instability, caused by interactions between negative ions in the jet flow via electron attachment as <TEX>$O_2+e{\rightarrow}O_2{^-}$</TEX> when AC electric fields are applied. This was confirmed by experiments in which a variety of gaseous jets were ejected from a nozzle to which DC voltages and AC frequencies and voltages were applied, with ambient air between two deflection plates connected to a DC power source. Experiments in which jet flows of several gases were ejected from a nozzle and AC electric fields were applied in coflow-nitrogen provided further evidence. The flow instability occurred only for oxygen and air jets. Additionally, jet instability occurred when the applied frequency was less than 80 Hz, corresponding to the characteristic collision response time. The effect of AC electric fields on the overall structure of the jet flows is also reported. Based on these results, we propose a mechanism to reduce jet flow instability when AC electric fields are applied to the nozzle.

Early detection of Parkinson’s diseases by using the relation between time response and movement characteristics of human’s arms

Parkinson’s and stroke diseases are closely linked to the brain of the elderly. This study was to investigate the early detecting method of Parkinson’s disease by using the relation between the brain time response and the arm movement characteristics. 120 Healthy people were examined and classified into 4 groups of ages ( 60 years old).The relationship between the two parameters were conducted by using the self-made electronics set which had an accelerometer attached on the hammer; and pattern generator using star-pattern with 9-position lighted keypad. Several simple and complex light patterns were designed to test the brain function of the elderly. The experimental treatments were subjected to 4×2 Factorial Experiment in Completely Randomized Design (CRD). The results showed that the time response of the group of+60’s years old was the longest compared with other group with P<0.01. Based on the experiments on pattern-position approach, those selected samples with 4 groups of age completed the experiment with a sample pattern faster than the complex pattern in all 4 groups of age with P<0.01. The acceleration signal’s patterns in 20-40 years old and +60 years old were found polynomial and linear signal patterns, respectively. The relationship between the time response and acceleration signal were found negative monotonic correlated ( 0.835, P < 0.01). Therefore, this finding could identify the healthy people without Parkinson’s disease with accuracy of 99.58 %. The results could be concluded that relationship between the time response and the acceleration signal could predict Parkinson’s disease and related diseases in the future.