Transmission Time Difference Research Articles

A system to detect vibration sources using the difference in vibration transmission time.

A system to detect vibration sources using the difference in vibration transmission time.

A Minimum Loss Routing Algorithm Based on Real-Time Transaction in Energy Internet

Due to capacity constraints and the uneven distribution of resources, it becomes a trend that multiple microgrids are interconnected as a net structure through energy routers. With the large-scale penetration of distributed energy, the supply mode of energy networks has been gradually transformed into multisource, multipath, and networked supply. In order to adapt to the energy supply mode and the real-time power transaction, a minimum loss routing (MLR) algorithm based on real-time transaction is proposed to realize the end-to-end energy transmission. On the basis of bidding information, the real-time transaction is introduced to determine the source and destination address of power transmission and the amount and transmission time of power flows. Then, an MLR is selected for transaction power, which minimizes the power loss caused by conversion and transmission. As the key of power real-time transaction, the solutions to transmission time difference, single-loop or double-loop power supply modes, and congestion managements are incorporated with the Dijkstra algorithm to find a no-congestion MLR in this paper. Finally, the effectiveness of the proposed optimization algorithm in the selection of MLR and congestion managements is verified by simulations.

Securing RF Communication Using AES-256 Symmetric Encryption: A Performance Evaluation

Radio Frequency (RF) communication plays a vital role for sensor node data transmission, which typically runs on top of lightweight protocol such as Constrained Application (CoAP) and Trivial File Transfer Protocol (TFTP). Introducing a cryptographic scheme to the process is known to be the common and most efficient method to protect RF communication. This paper presents the performance comparison of AES-encrypted data transmission over RF communication via Raspberry Pi boards, experimented on a client-server architecture. The performance analysis is measured based on throughput metric and the transmission time delay when sending three types of payload which are, a plaintext data, a ciphertext with padding and a ciphertext without padding. The result from the study indicates that there is a significant difference in data transmission time between the three types of data due to the data expansion factor. The result also showed that adding padding to the ciphertext has increased the data size slightly but not significant enough to affect transmission time of ciphertext.

Securing RF Communication Using AES-256 Symmetric Encryption: a Performance Evaluation

Radio Frequency (RF) communication plays a vital role for sensor node data transmission, which typically runs on top of lightweight protocol such as Constrained Application (CoAP) and Trivial File Transfer Protocol (TFTP). Introducing a cryptographic scheme to the process is known to be the common and most efficient method to protect RF communication. This paper presents the performance comparison of AES-encrypted data transmission over RF communication via Raspberry Pi boards, experimented on a client-server architecture. The performance analysis is measured based on throughput metric and the transmission time delay when sending three types of payload which are, a plaintext data, a ciphertext with padding and a ciphertext without padding. The result from the study indicates that there is a significant difference in data transmission time between the three types of data due to the data expansion factor. The result also showed that adding padding to the ciphertext has increased the data size slightly but not significant enough to affect transmission time of ciphertext.

An implementation of ultrasonic water meter using dToF measurement

A method of the ultrasonic transmission time difference (ToF) flow measurement is the one which is mainly applied to large diameter flow meters by incorporating high power digital signal processing...

Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates.

Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

A methodology for determining complex permittivity of construction materials based on transmission-only coherent, wide-bandwidth free-space measurements

An integrated methodology for determining the unique combination of complex permittivity based on measured transmission coefficient and time difference of arrival (TDOA) information in free-space measurements is proposed. The methodology consists of an estimation procedure of the real part of complex permittivity based on TDOA, and a root-searching procedure based on parametric system identification (SI) together with an error sum of squares (SSE) criterion. Generally, non-unique combinations of dielectric constant and loss factor are encountered when lossy or low-loss materials are measured and the proposed methodology is aimed at the determination of unique combinations of dielectric constant and loss factor for such materials. The proposed methodology is validated by measurements of several materials with known dielectric properties . The estimated complex permittivity values for Teflon , Lexan , Bakelite , and concrete are in good agreement with those reported in the literature. The method has potential for in-situ measurement of dielectric properties for construction materials. Applicability and limitations of the methodology are discussed.

Local gas holdup measurement of a bubble column using SONIA-ultrasonic non-invasive method

A non-invasive technique for local gas holdup measurement of a bubble column using Self-Organized Network inspired by Immune Algorithm (SONIA) neural network and ultrasonic method is investigated. The energy attenuation and the transmission time difference of ultrasound are used as measurement parameters to obtain the local gas holdup in an air–water dispersion system using SONIA neural network reconstruction. Bubble size distributions in the bubble column are obtained by using a photographic method. The experimental results and simulations on three different mean bubble size condition show that the errors of SONIA neural network method is 1/9 times lower than those of the conventional back-propagation neural network. The results show a good agreement with measured data.

Use of Neural Network-Ultrasonic Technique for Measuring Gas and Solid Hold-ups in a Slurry Bubble Column Bubble Colum

A novel technique for measuring simultaneously the gas and solid hold-ups in a slurry bubble column using a combination of neural network-ultrasonic method was investigated in this study. A one-dimensional model using the basic parameters of ultrasound (the energy attenuation and the velocity change in terms of the transmission time difference) for measuring the gas and the solid hold-ups has been proposed to show the complexity of the system. The three layers feedforward neural network (3-FFNN) structure has been used to try and solve the nonlinear relationship between parameter sensing and measurement purpose. An adequate selection of the neural network structure has been chosen to perform the relationship between the measurement sensing (input of the network) and the measurement purpose (output of the network). Preliminary representation results of the gas and the solid hold-ups using the proposed method compare relatively well with measured data.

Beating in Membrane Potential Mediated by Cortical γ-Oscillations for Reading Out Synchronous Neuronal Activities Over Distant Cortical Areas

I investigate whether cortical γ-oscillations are relevant to reading out synchronous neuronal firings that are distributed over the brain. A cortical neural network model is proposed and simulated. The model consists of two sensory networks (SI and SII) and one coincidence-sensitive network (CS). γ-oscillatory inputs and external stimuli are applied to interneurons and projection neurons of the sensory networks, respectively. The SI and SII networks project to the CS network in a divergent/convergent manner. Here I show that beating in membrane potential of CS neurons mediates the detection of synchronous neuronal firings between the SI and SII networks. A slight increase (a few Hz) in difference between frequencies of the γ-oscillations in the SI and SII networks generates the beating in the CS network. The synchronous neuronal firings are detected at each peak of the beating, regardless of difference in signal transmission time between SI-to-CS and SII-to-CS pathways.

Simultaneous Measurement of Mean Bubble Diameter and Local Gas Holdup Using Ultrasonic Method with Neural Network

One of the greatest challenges in the characterization of bubbles in a bubble column has been the prediction of the bubble diameter and the gas holdup. In this study a novel technique for predicting the mean bubble diameter and the local gas holdup using a non-invasive ultrasonic method with neural network was investigated. The measurement parameters of the energy attenuation and the transmission time difference of ultrasound are used to obtain the mean bubble diameter and the local gas holdup in an air-water dispersion system using neural network reconstruction. Bubble size distributions in a 2-D bubble column are obtained experimentally by using a photographic method. An adequate selection of the neural network structure has been carried out to represent the training data. The representative results using the present structure show good agreement with the measured data.

Slotted aloha with PCT (power control during transmission) scheme using capture effect

This paper proposes two new access protocols, wherein the power control during transmission (PCX) scheme attempts improvement of the throughput by capture effect; this scheme is applied to s-ALOHA. Either method solves the problem of contradiction between the packet transmission time difference required in PCT scheme and the synchronized transmission as the basic requirement in PCT scheme and the synchronized transmission as the basic requirement in s-ALOHA. The first protocol is the s-ALOHA with capture interval (s-ALOHA/CI), which is concerned with the fixed-length packet format. A capture interval is provided in the first part of the slot, wherein the transmission time is selected at random to provide the transmission time difference. The second protocol is s-ALOHA with tail synchronization (s-ALOHA/TS), which is concerned with the variable-length packet format. Utilizing the variable-length property, the tail of the packet is synchronized to the tail of the slot and the packet is transmitted. Then the packet length difference produces the transmission time difference. It is verified through evaluation by analysis and simulation that the throughput performance of traditional s-ALOHA is greatly improved in either protocol by the capture effect. Especially, in contrast to the deterioration of the effective throughput of the traditional s-ALOHA due to the slot loss, it is verified that the performance of s-ALOHA/TS is better than that of the fixed-length packet scheme. These high-performance protocols will serve as a powerful means of realizing the effective operation of VSAT network, etc., with the synchronization function.

Auditory brainstem potentials in sons of alcoholic fathers.

With the use of event-related brain potentials we have observed sensory as well as cognitive deficits in abstinent alcoholics. By recording auditory brainstem potentials (BSP) from abstinent alcoholics we demonstrated significant delays in brainstem transmission time. We have also reported that P3 amplitudes are significantly reduced in abstinent alcoholics compared to control subjects. Although the neurophysiological deficits observed in abstinent alcoholics are presumed to be alcohol-related effects, it is possible that some of these deficits may exist prior to alcohol exposure, and may be present in subjects at high risk for alcoholism. We have recently observed significantly reduced P3 components in young sons of alcoholics similar to those observed in abstinent alcoholics. In the present study, we examined auditory BSPs in young boys at high risk for alcoholism and matched controls. We found no statistically significant difference in brainstem transmission time between high risk individuals and matched control subjects. These findings suggest that while some brain deficits observed in abstinent alcoholics may antecede the development of alcoholism (P3) and may represent a predisposing factor, other deficits (BSP) appear to be the consequence of alcohol and/or nutritional-related effects.

LEFT VENTRICULAR SYSTOLIC TIME INTERVALS BY DOPPLER-COMPARISON WITH CAROTID PULSE METHOD

We compared left ventricular systolic time intervals (L STI's) derived from pulsed Doppler(D) and from conventional(C) carotid pulse tracing(CPT) and phonocardiography(PCG) in 24 subjects, aged 1.7 to 18.5 yrs, median=12.1 yr. Using the apical 2-chamber view, D frequency-time curves from the proximal ascending aorta were recorded simultaneously with CPT,PCG and ECG. L STI's from the D tracings were measured as follows: pre-ejection period (PEP)-beginning of QRS to onset of D systolic upstroke; ventricular ejection time(VET)-onset of D systolic upstroke to maximal end-systolic flow reversal. The difference in pulse transmission time between onset and end of systole resulted in a systematically shorter PEP and longer VET by C. C PEP was best predicted by the regression equation C PEP=1.03(D PEP)-14, and C VET by C VET=0.99(D VET)+8. The cumulative distribution of the error of the predicted values and correlation coefficients(r) using these formulae were:

Central Transmission Time Differences in the Auditory Brainstem Response as a Function of Sex, Age, and Ear of Stimulation

Averaged auditory brainstem responses (ABRs) to monaural clicks were recorded from twenty-nine men and women and twenty children. Differences in the wave I to wave V transmission time, and wave I to wave III transmission time as a function of ear of stimulation and reference, sex, size and age were investigated. The wave I-V transmission time was shorter for the women compared to the men. Individual wave latencies were compared and the transmission time difference was found to be due to small, incremental differences between successive waves rather than to one particular wave component. Size differences, as measured by nasion-inion length and subject height, did not correlate to the transmission time difference and did not appear to contribute to the sex difference. An ear of stimulation difference was found in the women's group. The sex difference in transmission time was seen in the children's data, but the difference was not significant. Thus, sex differences, age differences, and ear of reference differences are seen in ABR transmission times.

Kinetocardiogram, Phonocardiogram, and Arterial Pulse Waves During Acute Hemodynamic Changes

The effects of drugs that produce known hemodynamic alterations were assessed on externally recorded pulse waves, heart sounds, and the relationship of these to each other and to the electrocardiogram. The shape of the carotid pulse and the carotid-femoral pulse-wave transmission time difference showed changes that could be related to alterations in central arterial distensibility. The ratio of the second to the first positive inflection, and of the incisura to the first positive inflection of the carotid pulse wave, increased following use of drugs which raised mean arterial pressure and decreased after those which lowered blood pressure. The carotid-femoral transmission time difference decreased with vasopressor agents, increased with amyl nitrite and hexamethonium, and showed no consistent change after isoproterenol. Left ventricular ejection time, measured from the carotid pulse, changed in relation to heart rate, increasing with cardiac slowing and decreasing when the rate accelerated. The ejection time index remained unchanged except for a slight increase following amyl nitrite and a decrease after hexamethonium. Alterations in isovolumic contraction time approximately paralleled changes in diastolic pressure. The ratio of diastolic pressure to isovolumic contraction time provides an index of the rate of rise of left ventricular pressure. The quotient of diastolic pressure divided by isovolumic contraction time increased with adrenergic stimulation (isoproterenol) and decreased after ganglion blockade. It was not significantly changed by angiotensin II, methoxamine, or amyl nitrite. The interval between the onset of QRS and the beginning of the first heart sound (Q-S 1 ), shortened considerably after isoproterenol and moderately following amyl nitrite. It increased after hexamethonium and remained essentially unchanged following angiotensin II or methoxamine. These results suggest that the Q-S 1 interval may reflect ventricular contractility in the absence of mitral valvular disease. The amplitude of the first heart sound appeared to be a sensitive indicator of ventricular contractility increasing with isoproterenol and amyl nitrite, decreasing with hexamethonium and remaining unchanged following use of angiotensin II or methoxamine.