Low Time Delay Research Articles

Performance Analysis of MAC Layer Protocols for WSN with Considering the Effects of Hidden Node Problem

In this paper, the effects of the hidden node problem in Wireless sensor networks are studied on three different MAC protocols using various field distances and various numbers of nodes. This study provides the best number of nodes to be disseminated in a specific field distance depending on the needed performance metrics. Six performance metrics are used in this study, which are Goodput, Throughput, Packet delivery ratio (PDR), Residual Energy, Average Delay, and the first and last node dead in the network. IEEE 802.11, IEEE 802.15.4, and time division multiple access (TDMA) protocols are used. Results show that TDMA gives the best energy conservation and high delay time with high PDR, while IEEE 802.11 provides the best throughput and goodput results and low delay time.

Tailoring temperature stability of MgAl2O4 microwave dielectric ceramic via (Cu0.5Ti0.5)3+ co-substituted

In this work, the MgAl2-x(Cu0.5Ti0.5)xO4 (x ​= ​0, 0.04, 0.08, 0.12, 0.16, and 0.20) ceramic system was synthesized using the solid-state route. The crystalline phases, crystal structure,and microwave dielectric properties of the samples were investigated. The XRD data presented a typical spinel structure of MgAl2O4 and was processed using the Rietveld refinement method. TiO2, Al2TiO5 and MgTi2O5 were considered as secondary phases. SEM indicated that the densification was affected by the (Cu0.5Ti0.5)3+ content and sintering temperature. The successful fabrication of MgAl2-x(Cu0.5Ti0.5)xO4 and the presence of MgTi2O5 were confirmed by EDS. The densification, secondary phases and cation vacancies were responsible for the variation of Qf values. The εr values were dominated by secondary phases and ionic polarizability. Meanwhile, secondary phases and bond valence had a significant influence on the τf values. The optimum microwave dielectric properties (Qf ​= ​42,036 ​GHz, εr ​= ​8.72 and τf ​= ​-5.0 ​ppm/°C) were obtained. Temperature stability was improved by 93.8% when compared to pure MgAl2O4 (τf ​= ​-80.0 ​ppm/°C). The as-prepared ceramics possess low transmission delay time, high temperature stability, preferable frequency selective characteristics, and low dielectric loss.

Predictors of pre-hospital delay in seeking treatment among Jordanian patients with ST elevation myocardial infarction during COVID 19 pandemic

Pre-hospital delay lead to delay in receiving appropriate and timely reperfusion therapy among patients with STEMI, which increases morbidity and mortality rate. The current study aimed to explore predictors of pre-hospital delay time among Jordanian patients with STEMI during COVID 19 Pandemic. A descriptive cross-sectional design was used on a convenience sample of 163 patients diagnosed with STEMI. Multiple linear regression was used to explore the predictors of pre-hospital delay time. The mean pre-hospital delay time was 2.7 hours (SD = 1.9). Only 3% of patients attended the hospitals within the first hour of the onset of symptom, and 38% of patients used civil defense ambulance services to present to hospitals. Having a family history of cardiac disease and being medically insured were associated with lower pre-hospital delay time. Jordanian patients with STEMI have a lower delay time when compared with other countries during COVID 19 pandemic. Many demographic and clinical factors were found to cause pre-hospital delay, and efforts should be made to raise patients' awareness regarding the consequences of longer pre_hospital delay time.

A CFAR Algorithm Based on Monte Carlo Method for Millimeter-Wave Radar Road Traffic Target Detection

The development of Intelligent Transportation Systems (ITS) puts forward higher requirements for millimeter-wave radar surveillance in the traffic environment, such as lower time delay, higher sensitivity, and better multi-target detection capability. The Constant False Alarm Rate (CFAR) detector plays a vital role in the adaptive target detection of the radar. Still, traditional CFAR detection algorithms use a sliding window to find the target limit radar detection speed and efficiency. In such cases, we propose and discuss a CFAR detection method, which transforms the Monte Carlo simulation principle into randomly sampling instantaneous Range–Doppler Matrix (RDM) data, to improve the detection ability of radar for moving targets such as pedestrians and vehicles in the traffic environment. Compared with conventional methods, simulation and real experiments show that the method breaks through the reference window limitation and has higher detection sensitivity, higher detection accuracy, and lower detection delay. We hope to promote the detection application of millimeter-wave radar in road traffic scenes.

Blockchain-Based Incentive-Compatible Reputation Management System in Vehicular Networks

In Vehicular Networks, vehicles share information to improve traffic efficiency and safety. However, false information incurs severe damage or injuries because of malicious nodes. Althogh many schemes have been implemented for detection of false information,, there are problems concerning inadequate data security, large processing delay, weaker precision in detecting malicious nodes. In this paper, we put forward a Blockchain-based incentive-compatible trust management system. It provides a succinct and effective incentive mechanism to stimulate vehicles to broadcast road-related emergency information and vicinity vehicles to evaluate its timeliness. We also propose a novel method to calculate the reputation score to reflect the history behavior better. The transactions on the reputation scores are recorded in a consortium Blockchain consisted by Road Side Unit (RSU). The system has been experimentally validated to have a lower time delay and higher accuracy, and more accuracy reputation scores in Vehicular Networks.

Design of a Dynamic ADC Comparator with Low Power and Low Delay Time for IoT Application

Design of a Dynamic ADC Comparator with Low Power and Low Delay Time for IoT Application

Utilization of HEVC ChaCha20-Based Selective Encryption for Secure Telehealth Video Conferencing

Coronavirus (COVID-19) is a contagious disease that causes exceptional effect on healthcare organizations worldwide with dangerous impact on medical services within the hospitals. Because of the fast spread of COVID-19, the healthcare facilities could be a big source of disease infection. So, healthcare video consultations should be used to decrease face-to-face communication between clinician and patients. Healthcare video consultations may be beneficial for some COVID-19 conditions and reduce the need for face-to-face contact with a potentially positive patient without symptoms. These conditions are like top clinicians who provide remote consultations to develop treatment methodology and follow-up remotely, patients who consult about COVID-19, and those who have mild symptoms suggestive of the COVID-19 virus. Video consultations are a supplement to, and not a substitute for, telephone consultations. It may also form part of a broader COVID-19 distance care strategy that contains computerized screening, separation of possibly infectious patients within medical services, and computerized video-intensive observing of their intensive care that helps reduce mixing. Nowadays, the spread of the COVID-19 virus helps to expand the use of video healthcare consultations because it helps to exchange experiences and remote medical consultations, save costs and health procedures used to cope with the pandemic of the COVID-19 virus, and monitor the progress of treatment plans, moment by moment from a distance with precision, clarity and ease. From this perspective, this paper introduces a high-efficiency video coding (HEVC) ChaCha20-based selective encryption (SE) scheme for secure healthcare video Consultations. The proposed HEVC ChaCha20-based SE scheme uses the ChaCha20 for encrypting the sign bits of the Discrete Cosine Transform (DCT) and Motion Vector Difference (MVD) in the HEVC entropy phase. The main achievement of HEVC ChaCha20-based SE scheme is encrypting the most sensitive video bits with keeping low delay time, fixed bit rate of the HEVC, and format compliance. Experimental tests guarantee that the proposed HEVC ChaCha20-based SE scheme can ensure the confidentiality of the healthcare video consultations which has become easy to transmit through the internet.

E-CIS: Edge-based classifier identification scheme in green & sustainable IoT smart city

• E-CIS changes the traditional centralized architecture and realizes low time delay and efficient identification of IoT devices based on edge computing. • The types of IoT devices E-CIS can identify keeps growing. • All gateways of E-CIS have the continuous learning ability synchronously. Smart city has brought the unprecedented development and application of Internet of things (IoT) devices. Meanwhile, since both of the quantity and the type of IoT devices are growing rapidly, how to quickly identify the type of IoT devices is of paramount importance, especially in the fields of IoT Device Security, IoT Forensics, Cyber Defense, and Cyber Threats Intelligence Sharing, to make the IoT smart city green and sustainable. Traditional identification mode based on device or gateway often suffers from their limited computing and storage resources. Our work is motivated by the observation of the emergence of edge computing, in which computing and storage servers are placed in close proximity to IoT/mobile devices. In this paper, we propose an Edge-based Classifier Identification Scheme (E-CIS) for IoT Devices, where the neighboring edge servers provide powerful computing and storage capabilities. E-CIS changes the traditional centralized architecture and realizes low time delay and efficient identification of IoT devices based on edge computing. Experiments show that the average identification accuracy is as high as 99.2%. Besides, the optimization and security of the classification model can be maintained by the edge servers at the same time.

Phase change material based passive battery thermal management system to predict delay effect

In the modern scenario of the automobile industry there is a translation from conventional fuel vehicles to electric vehicles as a set to reduce carbon percentage. High power Lithium-ion batteries are the main power source of this vehicle to drive the powertrain, but due to the natural influence of various hot environmental conditions, there is a significant reduction in mileage of vehicle which is not desirable because a lithium-ion battery pack covers 50 to 60% whole cost of vehicle. To tackle this problem from recent years there are several types of research have been performed over active and passive thermal management techniques in which passive thermal management system is widely growth from recent years due to its numerous working advantages with the low-cost application. In the present study, we performed PCM based passive thermal management study over 60 Cell 18,650 Lithium-ion battery packs which are considered to be working for automobile applications. The high-power energy density battery is submerged with a layer of PCM to investigate the delay effect caused by the battery pack to resists the set limit of the threshold temperature range. The output field results from numerical investigation are predicted using neural network approach in which a multi-objective optimization strategy is proposed between battery pack delay effect for selected paraffin wax and RT-18 PCM against its given C-rate. furthermore, liquid fraction rate is monitored for the fixed temperature limit in varying C-rate condition, for optimization strategy Fixed temperature is taken as a function for time delay by PCM addition with liquid fraction rate of PCM over the varying C-rate condition. Correlations suggest paraffin wax is the best choice for a set temperature limit below 60 °C because paraffin wax is found to be melted faster and acts as a resistance to increase the temperature of the cell. The best fit line from the linear regression model using neural network approach suggest best fit line as the time delay is the function of liquid fraction rate over the selected PCM configuration. The highest time delay is occurred in case of paraffin wax PCM as 11,900 s for 1C rate and lowest time delay is occurred as 10,000 s for 1C rate in case of RT-18.

Wideband Underwater Wireless Optical Communication Based on Multi-Carrier Autoencoder

Underwater wireless optical communication (UWOC) has attracted considerable attention as a technology with high data rates and low time delays. However, the light scattering in water spreads beam pulse temporally, thereby resulting in time-varying underwater optical channels with inter-symbol interference (ISI) especially when the data rate is very high. To overcome this problem, in this letter, a multi-carrier autoencoder (AE) is proposed to incorporate the direct current optical orthogonal frequency-division multiplexing (DCO-OFDM) scheme into the AE network. In this way, proper constellation mapping and demapping schemes can be learned to cooperate with the DCO-OFDM modulation and the DC bias can be adaptively adjusted, efficiently dealing with the time-varying diffuse channel. The simulation results indicate that the proposed multi-carrier AE can achieve superior performance compared with other state-of-the-art techniques.

Enhanced prompt trigger optical switching using nonlinear photonic crystal ring resonator for application on all-optical AND/NAND and OR/NOR logic function

Abstract Nowadays, the development of optical telecommunication systems requires more efficient all-optical elements appreciation to their high data transmission speeds and reduced electromagnetic interferences. In this work, our objective is to attest by simulation a design of an optical switch using 2D photonic crystals from polystyrene, an organic polymeric material with high Kerr non-linearity. This excellent ultra-fast switching leads us to the exploited in the construction of two new structures of all-optical AND/NAND and OR/NOR logic gates. These structures based on non-linear ring resonator NRR of different radius in order to operate a telecom wavelength of 1550.3 µm using RSoft (Full-Wave) software. The average contrast intensity is between 15.52 and 23.42 dB and low delay time varied from 20 fs to 5.0 ps. Hence, resulting a very high output signal for ON-switching (82–130% of P in) and a weak signal for OFF-switching (0.2–7% of P in) through a minimum threshold power around of 1.2 mW/μm2.

A cerebellar-based solution to the nondeterministic time delay problem in robotic control

The presence of computation and transmission-variable time delays within a robotic control loop is a major cause of instability, hindering safe human-robot interaction (HRI) under these circumstances. Classical control theory has been adapted to counteract the presence of such variable delays; however, the solutions provided to date cannot cope with HRI robotics inherent features. The highly nonlinear dynamics of HRI cobots (robots intended for human interaction in collaborative tasks), together with the growing use of flexible joints and elastic materials providing passive compliance, prevent traditional control solutions from being applied. Conversely, human motor control natively deals with low power actuators, nonlinear dynamics, and variable transmission time delays. The cerebellum, pivotal to human motor control, is able to predict motor commands by correlating current and past sensorimotor signals, and to ultimately compensate for the existing sensorimotor human delay (tens of milliseconds). This work aims at bridging those inherent features of cerebellar motor control and current robotic challenges—namely, compliant control in the presence of variable sensorimotor delays. We implement a cerebellar-like spiking neural network (SNN) controller that is adaptive, compliant, and robust to variable sensorimotor delays by replicating the cerebellar mechanisms that embrace the presence of biological delays and allow motor learning and adaptation.

Principles-based accounting standards and the timeliness of annual reports: evidence from China

PurposeThis paper addresses the role of principles-based accounting standards as a potential mechanism for reducing firms' time delay of annual reporting disclosure while improving the timeliness of accounting information. The paper also contributes to the existing literature by addressing the mediating effects of the financial reporting complexity and the audit workload on the link between principles-based accounting standards and the time delay of annual reporting disclosure.Design/methodology/approachThe focus is placed on an unbalanced panel of 20,943 samples over the period of 2007–2017.FindingsThe results show that the more principles-based the accounting standards are, the lower the time delay of annual reporting disclosure is, and the timelier the disclosure of accounting information is. The relationship between the two is more significant especially in the first two months after the end of the fiscal year. The findings are all robust after controlling for a series of sensitivity checks and endogenous concerns. From the mediating effect results, the authors find that principles-based accounting standards decrease the financial reporting complexity and the audit workload which in turn can help lower time delay of annual reporting disclosure. In addition, the negative effect of principles-based accounting standards on the time delay of annual reporting disclosure is more significant in the case that the company has “good news” including with no losses and receiving the standard auditing opinions. The results confirm the law of “good news announces early, bad news announces late.” Furthermore, the moderating effect results show that the higher the economic policy uncertainty index and the legal environment index, the lower the benefit of principles-based accounting standards to the timeliness of annual reports. The results of the economic consequences of timeliness suggest that the timely disclosure of accounting reporting will bring greater market reaction and contain more information, and the information of companies that disclose annual reports timely are more transparent.Originality/valueThis paper studies the impact of accounting standards on the timeliness of annual report disclosure, which enriches the literature in the field of macro policies and micro-enterprise behaviors.

Bone collision detection method for robot assisted fracture reduction based on force curve slope

Background and objectiveThe application of robot technology in fracture reduction ensures the minimal invasiveness and accurate operation process. Most of the existing robot assisted fracture reduction systems don't have the function of bone collision detection, which is very important for system safety. In view of the deficiencies in the research of this field, a broken bone collision detection method based on the slope ratio of force curve was proposed in this paper, which could realize the real-time detection. MethodsIn order to analyze the factors influencing the slope of force curve, a collision mechanical model based on three-element viscoelastic model was established. The effects of four factors on the slope ratio of the force curve were studied based on the mechanical model. The proposed collision detection model was analyzed in detail. By drawing slope ratio curves under various experimental conditions, the universality of the collision detection model was proved; by comparative simulation, the differences between the slope ratio curves before and after optimization were analyzed. The factors that affect the performance of the detection model were also analyzed. ResultsThe results of collision experiments show that the increase of moving speed of distal bone and soft tissue mass reduces the slope ratio, while the increase of collision angle increases the slope ratio. In the verification experiment, the minimum main peak of KRopt curve is 14.16 and the maximum is 220.7, the maximum interference value before the peak is 6.1. When the detection threshold is 10, the model can detect the collision state of the broken bone. It is also proved that after optimization, the model can effectively filter out invalid waveforms and reduce the occurrence of false detections. When a=5 and b=40, the detection model has sufficient stability and a low detection time delay. ConclusionThis research developed a broken bone collision detection method based on the slope ratio of the force curve. After optimization, the method has good adaptability under a variety of experimental conditions. The collision of broken bones can be judged by setting an appropriate detection threshold. The application of this method in the robot fracture reduction system will improve the safety of the system.

A Low Insertion Loss Variation Trombone True Time Delay in GaAs pHEMT Monolithic Microwave Integrated Circuit

A wideband true time delay is proposed based on 0.25- μm GaAs pHEMT technology. The novel trombone topology is adopted for achieving low variation in insertion loss of different delay states. The fourth-order and second-order inductive all-pass networks (APNs) are operating as delay cells between input and output lines. By selecting different transmission ways, 3 bit with the step of 14 ps and maximum delay range of 98 ps are realized. Measurement results show the insertion loss of 3.8-10.5 dB over the frequency bandwidth of 6-16 GHz. The variation in insertion loss is less than ±1.4 dB. The chip area with pads is 1.955 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the power consumption is 110 mW.

5G Technology and Its Application in the Seismograph Intelligence

In order to meet the national intelligent development needs of coal mines, construct smart mines, improve their safety production levels and finally realize the vision of flexible manpower line and unmanned development, the application of 5G communication technology in intelligent seismographs for underground coal mines was discussed in this study based on the development history and advantages of 5G technology. Next, the application of 5G technology in the intelligent development of coal mines and the main application scenarios were explored by combining its three major unique advantages: high speed, low time delay and wide connection. The emphasis was laid on studying the seismograph intelligence based on 5G module, and then the uplink and downlink rates of three major operators under the same environmental conditions as well as uplink and downlink rates of the same operator at different positions under the 5G environment were tested. After being connected to 5G module, the seismographs sent data to the server side with fixed IP address, it was verified through the test that the normal communication was enabled under both TCP and UDP forms, and on this basis, the functions of seismograph, namely data passthrough to server and wireless real-time data transmission, were realized.

Emissions in short-gated ns/ps/fs-LIBS for fuel-to-air ratio measurements in methane-air flames.

A study of short-gated 10 nanosecond (ns), 100 picosecond (ps), and 100 femtosecond (fs) laser induced breakdown spectroscopy (LIBS) was conducted for fuel-to-air ratio (FAR) measurements in an atmospheric Hencken flame. The intent of the work is to understand which emission lines are available near the optical range in each pulse width regime and which emission ratios may be favorable for generating equivalence ratio calibration curves. The emission spectra in the range of 550-800 nm for ns-LIBS and ps-LIBS are mostly similar with slightly elevated atomic oxygen lines by ps-LIBS. Spectra from fs-LIBS show the lowest continuum background and prominent individual atomic lines, though have significantly weaker ionic emission from nitrogen. A qualitative explanation based on assumed local thermodynamic equilibrium and electron temperatures calculated by the ${{\rm{N}}_{\rm{II}}}({{565}}\;{\rm{nm}})$ and ${{\rm{N}}_{\rm{II}}}({{594}}\;{\rm{nm}})$ emissions is presented. In studying line emission ratios for FAR calculation, it is found that ${{\rm{H}}_\alpha}({{656}}\;{\rm{nm}})/{{\rm{N}}_{\rm{II}}}({{568}}\;{\rm{nm}})$ is best for FAR measurements with ns-LIBS and remains viable for ps-LIBS, while ${{\rm{H}}_\alpha}({{656}}\;{\rm{nm}})/{{\rm{O}}_{\rm I}}({{777}}\;{\rm{nm}})$ is optimal for the ps-LIBS and fs-LIBS cases. Due to low continuum background and short time delay for spectra collection, fs-LIBS is very promising for high-speed FAR measurements using short-gated LIBS.

A novel design of fast and compact all-optical full-adder using nonlinear resonant cavities

In this paper, we report a new design of an all-optical full-adder using two nonlinear resonators. The PhC-based full-adder consists of three input ports (A, B, and C for input bits), two nonlinear resonant cavities, several waveguides, and two output ports (for the SUM and CARRY). Eight silicon rods and a nonlinear rod composed of doped glass form each resonant cavity. The well-known plane wave expansion technique is used to calculate the photonic band structure. It shows a wide photonic bandgap in the wavelength range of 1365–2074 nm covering the C and L optical transmission bands. The finite-difference time-domain method is applied to study the light propagation inside the full-adder. Our numerical results demonstrate when the incoming light intensity increases, the nonlinear optical Kerr effect appears and controls the direction of light emitted inside the structure as desired. The maximum time delay and footprint of the proposed full-adder are about 3 ps and 758.5 μm2, respectively. Therefore, due to the low time delay and small footprint, the presented design can be used as a basic mathematical operator in the all-optical arithmetic logic unit.

A scheme for enabling the ultimate speed of threshold switching in phase change memory devices

Phase change materials exhibit threshold switching (TS) that establishes electrical conduction through amorphous material followed by Joule heating leading to its crystallization (set). However, achieving picosecond TS is one of the key challenges for realizing non-volatile memory operations closer to the speed of computing. Here, we present a trajectory map for enabling picosecond TS on the basis of exhaustive experimental results of voltage-dependent transient characteristics of Ge2Sb2Te5 phase-change memory (PCM) devices. We demonstrate strikingly faster switching, revealing an extraordinarily low delay time of less than 50 ps for an over-voltage equal to twice the threshold voltage. Moreover, a constant device current during the delay time validates the electronic nature of TS. This trajectory map will be useful for designing PCM device with SRAM-like speed.

Autoencoder based underwater wireless optical communication with high data rate.

Underwater wireless optical communication (UWOC) has great potential to provide higher data rates and lower time delay communication compared to radio frequency and acoustic counterparts. However, UWOC systems with wide bandwidths are subject to photon absorption and scattering, which result in severe energy loss for optical beams and inter-symbol interference. To overcome these issues, this Letter interprets the UWOC system as an autoencoder (AE), named UWOC-AE, which takes advantage of the double Gamma function approximating channel impulse response of underwater optical links to learn the channel characteristics. Thus, within the AE framework, the encoder and decoder can be optimized jointly. Experiments indicate that the proposed UWOC-AE can achieve superior performance with high data rates compared to existing techniques.