Acceptable Time Delay Research Articles

An adaptive genetic algorithm with neighborhood search for integrated O2O takeaway order assignment and delivery optimization by e-bikes with varied compartments

To improve the dining experiences, online-to-offline (O2O) takeaway services with warm-keeping or refrigerated requirements are quickly expanding and becoming popular. However, single-compartment e-bikes are commonly used in takeaway platforms, which can only meet one kind of requirements and may result in an inflexible delivery. Within this context, a new type of e-bikes, namely e-bikes with mixed compartments, is introduced. Thus, warm-keeping and refrigerated orders can be delivered by one bike, namely on one route. This paper considers an integrated order assignment and delivery problem by e-bikes with warm, refrigerated, and mixed compartments (AD-EBM). To solve the problem, we develop a novel integer programming formulation to minimize the total cost by determining order assignments and finding optimal routes, and then some properties of the solutions are provided from the view of mathematics. An algorithm is designed by combining the self-adaptive genetic algorithm with the neighborhood search method (SGA-NS). Numerical experiments are conducted based on simulated different-scale takeaway instances. The experimental results highlight the excellent performance of the SGA-NS and the results are quite encouraging compared with Gurobi solver, SGA, and NS. The results of the model comparison demonstrate that the AD-EBM offers 12.38% total cost savings on average, compared to using only single-compartment e-bikes. A sensitivity analysis is performed to explore the effects of the mixed compartment costs, the customer acceptable delay time, the penalty costs for delays, and the e-bike capacity for the platform’s daily operations. Some management insights are provided to facilitate the O2O takeaway delivery.

Features of software implementing the prefix search method in cryptographically protected databases

The article addresses the specific considerations associated with the development of software implementing the prefix search method in cryptographically protected databases. This method is a variant of symmetric searchable encryption, which allows search among the encrypted data. The prefix search method allows searching for prefixes among encrypted data without the need for decryption. Such an approach resolves the issue of maintaining data confidentiality stored on remote or cloud servers. However, its usage introduces a set of issues that must be considered during the development of the corresponding software. The paper analyzes the requirements for software that implements the prefix search method, defines the software architecture, and justifies the choice of technologies and tools for software implementation, including ASP.NET, Java, JavaScript, PHP, Python programming languages, MongoDB database management system, and the FastAPI framework. A description of the deployment process of the corresponding software is provided. To assess the performance of the developed software, the well-known Apache JMeter tool for conducting load testing was utilized. The obtained performance evaluations of the proposed solution indicate acceptable time delays in processing relevant data search queries.

The Evaluation Technology of Manufacturer Intelligence Regarding the Selection of the Decision Support System of Smart Manufacturing Technologies: Analysis of China–South Africa Relations

With the development of international cooperation, South Africa (SA) has been China’s largest trading partner in Africa for several consecutive years. China and SA can build the digital “Belt and Road” to modernize the manufacturing system locally and optimize process control by benchmarking with the best-in-class manufacturers in each country. In this research, an evaluation technology of manufacturer intelligence regarding the selection of decision support system (DSS) of smart manufacturing technologies, analyzing China–South Africa relations, is described. Firstly, the three keys aspects that enable the technologies of DSS are discussed in detail. Then, one key technology, the manufacturers’ intelligent evaluation system with 15 indexes, was built. The indexes and their measurements are also proposed. Finally, a fusion method based on boosting with multi-kernel function (online sequential extreme learning machine based on boosting, Boosting-OSELM) is introduced. The purpose of Boosting-OSKELM is to combine several weak learners into a strong learner (lower mean square error, MSE) through an acceptable time delay. Finally, the case study is presented to demonstrate the improvement on the MSE and process time, showing a relative MSE improvement of 96.19% and a relative time delay ratio of 31.46%. Totally, the largest contribution of the proposed evaluation method in this study is the conversion of the history data saved by the manual scoring method into knowledge in accessible MES and resealable time delay, which will free up the expert workforce in the entire process. We expect this paper will help future research in this field.

Analysis of the Effects of the Two-Photon Temporal Distinguishability on Measurement-Device-Independent Quantum Key Distribution

Measurement-device-independent quantum key distribution (MDI-QKD) protects legitimate users from attacks on measurement devices. The decoy method allows for unconditionally secure quantum key generation using lasers. One of the most important issues in MDI-QKD is that photons from two independent lasers must be indistinguishable. Because Alice and Bob send Charlie laser pulses through separate fiber links, the arrival times of the pulses fluctuate independently. According to the Hong-Ou-Mandel (HOM) interference at Charlie's relay, the time delay between two photons has the greatest effect on distinguishability. However, to date, these effects have not been analyzed. Our study uses simulations to investigate the effects of two-photon temporal distinguishability in terms of the visibility of the HOM-dip of two photons on the final key rate of finite-size MDI-QKD. Furthermore, an acceptable time delay range was estimated based on photons with Gaussian spectral amplitude functions.

Dynamic Terrain Data Exchange in a Collaborative Terrain Editor

In a computer supported cooperative work (CSCW), data consistency between collaborating users is a crucial issue. Based on the type of the application, ensuring data consistency can be a lengthy process that takes time and affects the system’s performance. In most 3D application, terrain data are massive due to its size. Exchanging this data may be expensive and may cause significant delay. In a real-time collaborative terrain editor, this issue becomes more significant due to terrain data exchange is consistently occurred between collaborating users. We present a solution to perform a conflict-free dynamic terrain data exchange in a real-time collaborative terrain editor. Our objective is to develop a method that able to ensure data consistency amongst collaborating peers in real-time manner. The main idea of our method is to split the terrain into smaller patches and synchronize the changes efficiently by only exchanging the modified patches. We applied our solution to a collaborative terrain editor application to test its performance in a real-time collaborative editing session. The tests were done in multiple scenarios, using different patch model, brush size (in the terrain editor), and connection setup between server and collaborating clients. The result shows that our protocol is capable to maintain data consistency between collaborating clients in a real-time terrain edition session. The delay is varied and highly depends on the data size and client-server environment setup. The overall test shows that it is possible to perform a collaborative terrain editing with an acceptable response time delay. In this paper, we present our proposed method, the implementation, and the result data from the test.

VoIPChain: A decentralized identity authentication in Voice over IP using Blockchain

Confidentiality, availability, integrity, authentication, and non-repudiation when together became the top priority for secure communication. However, authentication is the first line of defense in all these security parameters. Unfortunately, several authentication mechanisms in the traditional methods cannot provide secure communication due to various vulnerabilities such as single point of failure and privacy issues. Furthermore, key distribution mechanisms such as Certificate Authority (CA) and Trusted Third Party (TTP) distribute keys over the central architecture fail, thus secure communication cannot occur. As a solution to these drawbacks, this paper proposes a new decentralized blockchain-based identity authentication mechanism for VoIP networks, VoIPChain. The proposed scheme utilizes the main features of the blockchain platform, such as immutability, transparency, and fault tolerance, to provide data privacy and secure communication in VoIP applications. The proposed scheme is evaluated as an actual implementation using the virtual Ethereum platform and Python language. The experimental results show that the proposed scheme is an efficient and cost-effective solution for the call process as a decentralized identity authentication system in VoIP. In addition, end-to-end secure call performance outperforms the existing blockchain-based authentication mechanisms by 30%–70% in terms of average time delay. The proposed scheme is almost ten times faster than the TLS process to authenticate between parties. Moreover, compared to fast but less secure basic methods over the SIP authentication the proposed scheme has an acceptable time delay in a call process.

Factors Affecting Demand Consolidation in Urban Air Taxi Operation

Urban air taxi (UAT) is envisioned as a point-to-point, (nearly) on-demand, and per-seat operation of passenger-carrying urban air mobility (UAM) in its mature state. A high flight load factor has been identified as one of the influential components in the successful operation of UAT. However, the uncertainties in demand, aircraft technology, and concept of operations have raised doubts about the viability of UAT. This study examines the impacts of exogenous parameters, such as demand intensity, demand spread, and ground speed, in addition to design parameters, including aerial speed, maximum acceptable delay, and reservations on average load factor and rate of rejected requests. The dynamic and stochastic problem of UAT fleet operation is studied by implementing a dynamic framework that aims to provide a solution to the problem via a discrete-event simulation. The results highlight the significance of demand spread, ground speed, and maximum acceptable delay in demand consolidation. Therefore, to ensure a high aircraft load factor, the UAT operator should specify the maximum acceptable delay and reservation time window given the demand pattern and ground-based transportation in the network.

Acute Coronary Syndromes and SARS-CoV-2 Infection: Results From an Observational Multicenter Registry During the Second Pandemic Spread in Lombardy.

BackgroundCOVID-19 had an adverse impact on the management and outcome of acute coronary syndromes (ACS), but most available data refer to March-April 2020.AimThis study aims to investigate the clinical characteristics, time of treatment, and clinical outcome of patients at hospitals serving as macro-hubs during the second pandemic wave of SARS-CoV-2 (November 2020-January 2021).Methods and ResultsNine out of thirteen “macro-hubs” agreed to participate in the registry with a total of 941 patients included. The median age was 67 years (IQR 58-77) and ST-elevation myocardial infarction (STEMI) was the clinical presentation in 54% of cases. Almost all patients (97%) underwent coronary angiography, with more than 60% of patients transported to a macro-hub by the Emergency Medical Service (EMS). In the whole population of STEMI patients, the median time from symptom onset to First Medical Contact (FMC) was 64 min (IQR 30-180). The median time from FMC to CathLab was 69 min (IQR 39-105). A total of 59 patients (6.3%) presented a concomitant confirmed SARS-CoV-2 infection, and pneumonia was present in 42.4% of these cases. No significant differences were found between STEMI patients with and without SARS-CoV-2 infection in treatment time intervals. Patients with concomitant SARS-CoV-2 infection had a significantly higher in-hospital mortality compared to those without (16.9% vs. 3.6%, P < 0.0001). However, post-discharge mortality was similar to 6-month mortality (4.2% vs. 4.1%, P = 0.98). In the multivariate analysis, SARS-CoV-2 infection did not show an independent association with in-hospital mortality, whereas pneumonia had higher mortality (OR 5.65, P = 0.05).ConclusionDuring the second wave of SARS-CoV-2 infection, almost all patients with ACS received coronary angiography for STEMI with an acceptable time delay. Patients with concomitant infection presented a lower in-hospital survival with no difference in post-discharge mortality; infection by itself was not an independent predictor of mortality but pneumonia was.

Conflict-free four-dimensional path planning for urban air mobility considering airspace occupancy

Urban air mobility (UAM) has attracted the attention of aircraft manufacturers, air navigation service providers and governments in recent years. Preventing the conflict among urban aircraft is crucial to UAM traffic safety, which is a key in enabling large scale UAM operation. Pre-flight conflict-free path planning can provide a strategic layer in the maintenance of safety performance, thus becomes an important element in UAM. This paper aims at tackling conflict-free path planning problem for UAM operation with a consideration of four-dimensional airspace management. In the paper, we first introduce AirMatrix, previously developed by the team, and extend it as a four-dimensional airspace management concept. On the basis of AirMatrix, we formulate the shortest flight time path planning problem considering resolution of conflicts with both static and dynamic obstacles. A Conflict-Free A* (CFA*) algorithm is developed for planning four-dimensional paths based on first-come-first-served scheme. The algorithm contains a novel design of heuristic function as well as a conflict detection and resolution strategy. Numerical simulation was carried out using the building information in a typical urban area in Singapore. The results show that the algorithm can generate paths resolving a significant number of potential conflicts in airspace utilization, with acceptable computational time and flight delay. The findings of this study will provide references for stakeholders to support the development of UAM.

A Novel Security Methodology for Smart Grids: A Case Study of Microcomputer-Based Encryption for PMU Devices

Coordination of a power system with the phasor measurement devices (PMUs) in real time on the load and generation sides is carried out within the context of smart grid studies. Power systems equipped with information systems in a smart grid pace with external security threats. Developing a smart grid which can resist against cyber threats is considered indispensable for the uninterrupted operation. In this study, a two-way secure communication methodology underpinned by a chaos-based encryption algorithm for PMU devices is proposed. The proposed system uses the IEEE-14 busbar system on which the optimum PMU placement has been installed. The proposed hyperchaotic system-based encryption method is applied as a new security methodology among PMU devices. The success of results is evaluated by the completeness of data exchange, durations, the complexity of encryption-decryption processes, and strength of cryptography using a microcomputer-based implementation. The results show that the proposed microcomputer-based encryption algorithms can be directly embedded as encryption hardware units into PMU and PDC devices which have very fast signal processing capabilities taking into considerations the acceptable delay time for power system protection and measuring applications and quality metering applications which is 2 ms and 10 ms, respectively. While proposed algorithms can be used in TCP or UDP over IP-based IEEE C37.118, IEC 61850, and IEC 61850-90-5 communication frameworks, they can also be embedded into electronic cards, smartcards, or smart tokens which are utilized for authentication among smart grid components.

Deploying battery swap stations for shared electric vehicles using trajectory data

• Proposing a novel Station-to-Point (S2P) Battery Swap Mode. • Extracting battery swap demand of Shared Electric Vehicles (SEVs) from trajectory data. • A data-driven approach to deploying and operating Battery Swap Stations (BSSs). • Setting up 53 scenarios to test the approach and the sensitivity of key parameters. • The desired quality of service was influential to the deployment and operation of BSSs. This paper proposed a novel Station-to-Point (S2P) Battery Swap Mode for Shared Electric Vehicles (SEVs), under which Battery Swap Stations (BSSs) have dedicated delivery vehicles transporting new/used batteries between BSSs and Battery Swapping Demand (BSD) points. We further developed a data-driven BSS location optimization model and day-to-day operation strategy, using a one-month GPS trajectory dataset containing 514 actual SEVs in Beijing. We set up 53 scenarios to test the model. In the baseline scenario, we found that the SEV fleet needed 15 BSSs, and each SEV, on average, needed 1.202 batteries and 0.031 delivery vehicles with the centralized management strategy applied. Through “what-if” scenarios, we found that the key parameters Q (the coverage rate of BSD points), R (the service radius of a BSS), and AADT (the acceptable average delay time) were influential to the outputs of interest.

From heart drug to propellant fuels: Designing nitroglycerin-ionic liquid composite as green high-energy hypergolic fluids

New-generation green bipropellants based on ionic liquids for aircraft have attracted the attention of researchers. However, the major defects of ionic liquid propellants are their low specific impulse and incomplete combustion, which limits their practical application. In this work, a series of novel hypergolic fluids were prepared by mixing oxygen-rich nitroglycerin (NG) with fuel-rich dicyanamide-based ionic liquids. The complete dissolution of NG in ionic liquids makes these hypergolic fluids became self-supplying oxygen composite fuels, which generate much less solid residual products than pure hypergolic ionic liquids (HILs). Moreover, the addition of NG inhibited the micro-explosion between fuel and white fuming nitric acid (WFNA), extended the contact time between fuel and oxidizer. And a proper amount of NG in the fuel could suppress the secondary combustion. These composite fuels have high density (>1 g cm−3), low viscosity (as low as 13.49 cP), wide liquid operating ranges and acceptable ignition delay time. Additionally, the specific impulses of the composite fuels were higher than pure HILs. For the first time, this work provides a simple and reliable method to control the ignition properties of HIL by adding oxygen-enriched additives.

An improved coordination control for a novel hybrid AC/DC microgrid architecture with combined energy storage system

This paper proposes a novel hybrid ac/dc microgrid (MG) architecture that integrates a combined energy storage system (ESS) for both ac and dc subgrids, which avoids the problems associated with the distributed ESSs with different state-of-charges (SoCs). To realize effective operation of the hybrid MG, this paper has also proposed an improved coordination control strategy between the combined ESS and the paralleled bidirectional interlinking converters (BILCs). First, a novel SoC-based adaptive droop control is designed for the combined ESS to provide dc bus voltage support and ac bus frequency support, and the lifetime of the combined ESS is extended because the overcharge and overdischarge can be avoided. Second, ac bus frequency and dc bus voltage are regarded as global parameters to enforce the power interaction between ac and dc subgrids. The power interactions between ac and dc subgrids can be proportionally allocated with the coordination coefficients to avoid an over-used BILC. Furthermore, the proposed distributed coordinated power control (DCPC) for BILCs network has plug-and-play capacity and allows an acceptable communication time delay and communication link failures. Finally, the effectiveness of the proposed coordination control strategy applied into the novel hybrid ac/dc MG system is verified by the real-time hardware-in-loop (HIL) tests.

Influence of Passenger Flow at the Station Entrances on Passenger Satisfaction Amid COVID-19

Railway stations are centers of mass accumulation of people. Additional regulations change the intensity of the flow of visitors and the time of entering the station. Delays become an essential factor affecting the perceived satisfaction with all services at stations. This paper analyzes the impact of the intensity of passenger flow in the key areas of the station (entrance groups) on the satisfaction of visitors with station functioning (by the example of Moscow railway stations). The authors of the paper used methods of observation to measure the current passenger flows at the entrances to the station and also collected secondary data on transport flows at city railway stations. To predict passenger flow, the authors used statistical methods to assess the relationship between variables and regression. The paper used a survey of passengers to analyze satisfaction with the functioning of railway station facilities and assess the acceptable delay time at the entrance/exit to the station. The article substantiates that in the context of current requirements for transport security, an important factor for perceived satisfaction with station services is the forecasting and management of passenger flows and control of time of entering the station.

Optimal breaker failure protection for potential over-limit short-circuit current

In this paper, an optimal breaker failure protection (OBFP) is proposed to deal with the risk of potential breaker failure which is caused by unpredictable over-limit short-circuit current (SCC). First of all, to avoid the severe consequence caused by directly opening the circuit breaker (CB) with unpredictable over-limit SCC, an ultrafast SCC forecasting method is adopted to detect the unpredictable over-limit SCC event. Once an over-limit SCC event is detected, any tripping signal corresponding to the CB will be temporarily blocked. The blocking signal will be kept until the SCC is reduced under the rated breaking capacity of the CB. Then the Thevenin equivalent model of the backside system interconnected to the bus is generated on-line to evaluate the effects of various potential current-limiting measures. Finally, a comprehensive strategy of OBFP consisting of multiple current limiting measures is put forward, which can reliably remove the above-mentioned extreme fault with an acceptable time delay and consequences. The effectiveness of OBFP is validated through various simulation test results.

Technical note: Effect of delayed analysis of cooled lithium-heparinized whole blood on the stability of ionized calcium, ionized magnesium, sodium, potassium, chloride, glucose, and lactate in samples from dairy cows

The objectives of this study were to describe the stability of bovine whole-blood electrolytes, glucose, and lactate in samples collected in lithium heparin tubes and stored in thermoconductive modules immersed in ice water. A total of 99 Jersey cows (40 first-parity, 18 second-parity, and 41 third-parity or greater cows) from a commercial dairy farm in West Texas were enrolled between June and July 2018. Blood was collected from the jugular vein using a 60-mL polypropylene syringe and equally distributed into 5 spray-dried evacuated lithium heparin tubes. Baseline samples were analyzed within 90 s of collection using a benchtop blood gas analyzer. The remaining 4 tubes were stored in a thermoconductive, passive-temperature-regulating module inside a cooler with ice water. At 30 min and 2, 4, and 8 h post-collection, samples were removed from the temperature-regulating module, gently inverted for 10 s, and analyzed. Repeated-measures models were built to evaluate the effect of time on the stability of ionized Ca (iCa), ionized Mg (iMg), Na, K, Cl, glucose, and lactate. Most of the analytes investigated remained stable up to 8 h under ice water storage conditions before analysis, including iCa, iMg, Cl, glucose, and lactate. However, Na and K were significantly affected by delayed analysis: Na remained stable up to 4 h post-collection, but K was not stable starting at 2 h post-collection. The results of this study are useful in helping future researchers and consultants to recognize acceptable time delays between whole blood collection and processing or analysis for electrolytes, glucose, and lactate.

Data Transmissions Using Hub Nodes in Vehicular Social Networks

Vehicular Social Networks (VSNs) consist of groups of individuals (i.e., people) who may share common interests, preferences and needs in the context of temporal spatial proximity on roads. In this environment, the impact of human social factors, such as mobility, willingness to cooperate and personal preferences, on vehicular connectivity is taken under consideration, thus extending the concept of Vehicular Ad-hoc Networks. In VSNs, vehicles are classified based on their social degree, a vehicle considered to be a “social” one if it accesses the vehicular social network and posts messages with a frequency higher than a given threshold. Therefore, to speed up the data dissemination process within a vehicular social network, a packet should be forwarded to those vehicles showing high social activity. In a previous paper, we introduced a new probabilistic-based broadcasting scheme called SCARF (SoCial-Aware Reliable Forwarding Technique for Vehicular Communications), and we analytically demonstrated its effectiveness in packet transmission reduction while guaranteeing network dissemination. In this paper, we assess SCARF in more realistic scenarios with real traffic traces, and we compare it with other similar techniques. We show that SCARF outperforms other approaches in terms of delivery ratio, while guaranteeing acceptable time delay values and average number of forwardings.

A Modified BA Anti-Collision Protocol for Coping with Capture Effect and Interference in RFID Systems

Radio frequency identification (RFID) technology has widely been used in the last few years. Its applications focus on auto identification, tracking, and data capturing issues. However, RFID suffers from the main problem of tags collision when multiple tags simultaneously respond to the reader request. Many protocols were proposed to solve the collision problems with good identification efficiency and an acceptable time delay, such as the blocking anti-collision protocol (BA). Nevertheless, most of these protocols assumed that the RFID reader could decode the tag’s signal only when there was one tag responding to the reader request once each time. Hence, they ignored the phenomenon of the capture effect, which results in identifying the tag with the stronger signal as the multiple tags simultaneously respond. As a result, many tags will not be identified under the capture effect. Therefore, the purpose of this paper is to take the capture effect phenomenon into consideration in order to modify the blocking BA protocol to ensure a full read rate, i.e., identifying all the tags in the frame without losing any tag. Moreover, the modifications include distinguishing between collision and interference responses (for the period of staying tags) in the noisy environments, for the purpose of enhancing the efficiency of the identification. Finally, the simulation and analytical results show that our modifications and MBA protocol outperform the previous protocols in the same field, such as generalized query tree protocols (GQT1 and GQT2), general binary tree (GBT), and tweaked binary tree (TBT).

A Fully Implantable Wireless ECoG 128-Channel Recording Device for Human Brain-Machine Interfaces: W-HERBS.

Brain–machine interfaces (BMIs) are promising devices that can be used as neuroprostheses by severely disabled individuals. Brain surface electroencephalograms (electrocorticograms, ECoGs) can provide input signals that can then be decoded to enable communication with others and to control intelligent prostheses and home electronics. However, conventional systems use wired ECoG recordings. Therefore, the development of wireless systems for clinical ECoG BMIs is a major goal in the field. We developed a fully implantable ECoG signal recording device for human ECoG BMI, i.e., a wireless human ECoG-based real-time BMI system (W-HERBS). In this system, three-dimensional (3D) high-density subdural multiple electrodes are fitted to the brain surface and ECoG measurement units record 128-channel (ch) ECoG signals at a sampling rate of 1 kHz. The units transfer data to the data and power management unit implanted subcutaneously in the abdomen through a subcutaneous stretchable spiral cable. The data and power management unit then communicates with a workstation outside the body and wirelessly receives 400 mW of power from an external wireless transmitter. The workstation records and analyzes the received data in the frequency domain and controls external devices based on analyses. We investigated the performance of the proposed system. We were able to use W-HERBS to detect sine waves with a 4.8-μV amplitude and a 60–200-Hz bandwidth from the ECoG BMIs. W-HERBS is the first fully implantable ECoG-based BMI system with more than 100 ch. It is capable of recording 128-ch subdural ECoG signals with sufficient input-referred noise (3 μVrms) and with an acceptable time delay (250 ms). The system contributes to the clinical application of high-performance BMIs and to experimental brain research.

Efficient Privacy-Preserving Dual Authentication and Key Agreement Scheme for Secure V2V Communications in an IoV Paradigm

The Internet of Vehicles (IoV) aims to provide a new convenient, comfortable, and safe driving way, and in turn enables intelligent transportation through wireless communications among road-side units, on-board units (OBUs), phones, and other devices inside a vehicle. However, significantly increasing reliance on wireless communication, control, and computing technology makes IoV more vulnerable to potential attacks, such as remote intrusion, control, and trajectory tracking. Therefore, efficient authentication solutions preventing unauthorized visitors need to be addressed to cope with these issues. Hence, in this paper we focus on the security and privacy-preserving by developing a dual authentication scheme for IoV according to its different scenarios. First, the OBU self-generates an anonymous identity and temporary encryption key to open an authentication session. Second, the legitimacy of the vehicle’s real and anonymous identity can be verified by trust authority (TA). After that, the vehicle’s reputation is evaluated according to its history interactive behavior and the session key for V2V can be finally established. There are three major advantages, including privacy-preserving and security enhancement without a burden of key management in the condition of acceptable time delay range, introducing trust evaluation into authentication protocol, as well as considering the vehicle behavior attributes in the new reputation evaluation method. In addition, we also prove the correctness of this scheme using the Burrows–Abadi–Needham (BAN) logic, and the performance comparison against the existing schemes is given as well.