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Modelling and testing of in-wheel motor drive intelligent electric vehicles based on co-simulation with Carsim/Simulink

期刊: IET INTELLIGENT TRANSPORT SYSTEMS, 2019; 13 (1)

To study the overall performance of the distributed drive intelligent electric vehicle (EV), a in-wheel motor drive (IWMD) vehicle is developed in this study. The configuration and 11-degrees of freedom model of IWMD EV is introduced firstly. Then, the co-simulation model of IWMD EV based on Carsim and Matlab/Simulink is established. The block design is employed for the co-simulation modelling, including the in-wheel motor model, driver model, tyre model, steering model, braking model, suspension model, aerodynamic model, and road surface model. The effectiveness and the reasonableness of the co-simulation model of IWMD EV are verified by the snake testing with on the campus road. The co-simulation model provides accuracy and reliable simulation method for the path-tracking and self-driving study of IWMD intelligent vehicle in the future.

IF:2.05

Study of the Underground Parts Identification and Saponins Content Prediction of Panax Notoginseng Based on FTIR Combined with Chemometrics

期刊: SPECTROSCOPY AND SPECTRAL ANALYSIS, 2019; 39 (1)

Phenomenon of adulterated traditional Chinese medicine (TCM) are still common in TCM market today. Unscrupulous traders used fibrous root powder pretending to be main root and rhizome powder of Panax notoginseng and such behavior has serious influence on the quality and efficacy of Panax notoginseng. In this study, we have established a rapid method to discriminate the main root, rhizome and fibrous root powder and detect saponins content of Panax notoginseng in order to provide some research bases for rapid quality assessment of Panax notoginseng. A total of 60 Fourier transform infrared (FTIR) spectra of the main root, rhizome and fibrous root powder of Panax notoginseng were collected, and ultra-high performance liquid chromatography (UPLC) was used for measuring the content of notoginsenoside R-1, ginsenoside R-g1, ginsenoside Rb-1 and ginsenoside Rd of samples. The origin data of identify model were processed by ordinate normalization and second derivative, and 2/3 of the 60 individuals were selected to form the calibration set by using Kennard-stone algorithm as well as the other 1/3 were used as validation set. Calibration set data were used to establish the discriminant model of support vector machine (SVM) and the cross-validation was used for screening optimal parameters c and g, and validation set data were used to verify the results of SVM discriminant model for external validation. The origin data used to predict saponins content were calculated by first (1D) and second derivative (2D), Savitsky-Golay smoothing with five, seven, nine, and eleven points. 2/3 of the 60 individuals were selected to form the calibration set and the rest were used as validation set. The orthogonal signal correction-partial least squares regression (OSC-PLSR) model was established by calibration set and the validation set was utilized to verify the results of the model for external validation. Results showed that, (1) with second derivative processing, the overlapped peak of FIIR spectra were efficiently separated and the resolution of the spectra has been improved. (2) The optimal parameters c and g of support vector machine calculated by cross-validation were 2.828 43 and 4.882 81 X 10(-4) respectively and the optimal accuracy rate of calibration set was 100%. (3) The parameter of support vector machine model was set as the optimal parameter and the accuracy rate of validation set was 100%, and all samples in validation set have been identified correctly. (4) The prediction content of greatest model of notoginsenoside R-1, ginsenoside R-g1, ginsenoside Rb-1 and ginsenoside Rd was close to the content measured by UPLC. The result indicated that, FTIR combined with support vector machine could effectively identify the main root, rhizome and fibrous root powder of Panax notoginseng. OSC-PLSR could accurately predict the content of four saponins of Panax notoginseng. In summary, the FTIR spectroscopy could provide a rapid and effective method for the quality control of Panax notoginseng.

IF:0.43

Compressive Spinal Codes

期刊: IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, 2019; 68 (12)

It is well known that spinal codes can essentially approach channel capacity for equiprobable source, and achieve seamless rate adaptation at the same time. But how to design an optimal spinal codes for non-equiprobable source is still an open problem. This paper proposes a novel Sparse Spinal (S-Spinal) codes design, which can essentially approach channel capacity for non-equiprobable and compressible source, and its seamless rate adaptation is also preserved. The main idea is to utilize source distribution information at the spinal decoder. The sparser the source is, the less symbols the receiver needs. The rateless feature of spinal codes can provide fine-grain compression ratio. The different decoder designs for Binary Symmetrical Channel (BSC) and Additive White Gaussian Noise (AWGN) channel are proposed, since their priori information is different. We also analyze and prove the S-Spinal codes with a practical pruning decoder can essentially achieve the channel capacity. The experimental results show that the proposed S-Spinal is very close to channel capacity of both BSC and AWGN channel for non-equiprobable source, and can achieve seamless rate adaption in practical system.

IF:5.34

Impact of Utilizing Construction Engineering and Inspection Consultants on Highway Construction Project Cost and Schedule Performance

期刊: TRANSPORTATION RESEARCH RECORD, 2019; 2673 (11)

State transportation agencies (STAs) are tasked with constructing and maintaining complex transportation networks while facing changes in agency construction staff with respect to age, experience level, turnover, retirement, and increasing levels of consulting services that are used to manage STA construction operations. To keep up with the increasing demands of projects, STAs are utilizing Construction and Engineering Inspection (CEI) consultants to fill the demand for construction-related human resources. However, the impact of using CEIs on project cost and schedule performance has not been quantified. The current work addresses this knowledge gap by analyzing a database of 305 completed highway construction projects across 16 STAs. The analysis found that projects that utilized CEI consultants had higher levels of full-time equivalent construction staffing than projects that utilized only agency staff. The use of CEI consultants had no impact on project cost compared with projects that relied solely on agency staff. Projects that used CEI consultants had an average cost overrun of 20.2% compared with agency-staffed projects, which experienced average schedule overruns of -7.7% (i.e., the project, on average, finished early). The schedule difference was statistically significant.

IF:0.75

Solvent viscosity induces twisted intramolecular charge transfer state lifetime tunable of Thioflavin-T

期刊: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 2019; 222 ()

Excited-state deactivation dynamics of Thioflavin-T (ThT) in gradual viscosity solvents were investigated. Femtosecond transient absorption spectra and dynamic decay curves both present significant distinction of ThT in different volume ratios binary mixtures solvents. Dynamics fitting lifetime of twisted intramolecular charge transfer (TICT) state is strongly dependent on solvents viscosity. Compared to rotation corresponding time of ThT in low viscosity solvent (0.6 cp) experimentally coincident well with Stokes-Einstein-Debye (SED) equation, the relation between rotation corresponding time and relatively high viscosity (5.9 cp to 1091.2 cp) is more consistent with fractional SED equation. Combined with optimized geometric structures of ThT by density functional theory and time-dependent density functional theory, further understand TICT state lifetime increases with increasing solvents viscosity. Our work provides a comprehensive understanding of fluorescence molecular rotor (FMR) deactivation process in different viscosity solvents and is helpful to design new FMR. (C) 2019 Elsevier B.V. All rights reserved.

IF:2.93

Research on the Influence of Haze for Detection System Based on Elastic Light Modulator

期刊: SPECTROSCOPY AND SPECTRAL ANALYSIS, 2019; 39 (2)

In recent years, haze phenomenon is becoming more and more serious in China. It not only harms people's health and air traffic caused by security risks, but also affects a lot of optics equipment used outdoor. In order to quantitatively analyze the effect of different haze levels on the performance of the trace gas concentration detection system based on the elastic light modulator, the test system was designed. The effect of different PM2. 5 concentration sample gas on the inversion of equivalent VOC gas concentration was quantitatively analyzed. In the experiment, different concentrations of PM2. 5 were collected in the field, and then mixed with the standard gas to be prepared. Finally, the comparison of the transmitted light spectrum and the measured gas concentration inversion data was made. The effect of PM2. 5 concentration on the system was quantitatively analyzed. In the experiment, formaldehyde and benzene were used as the gas to be measured. Six kinds of concentrations of the gas to be measured were prepared, and 6 haze concentration levels (from No. 1 to No. 6) were tested. The experimental results showed that when the PM2. 5 concentration increases, the system light energy absorption rate is significantly reduced. When the PM2. 5 concentration level is less than No. 3, the attenuation change is relatively slower, and when it is greater than No. 3, the attenuation effect is enhanced. When the PM2. 5 concentration is less than 150 g . m(-3), the test accuracy is better than 90%; When the concentration of PM2. 5 exceeds 150 g . m (-3) , the effect of inversion of VOC concentration becomes stronger. When 350 g . m (-3) is reached, the test error is nearly 30%. It can be seen that PM2. 5 concentration has a significant effect on the gas concentration detection of the optical modulation system.

IF:0.43

Real-time energy management for commute HEVs using modified A-ECMS with traffic information recognition

期刊: IET INTELLIGENT TRANSPORT SYSTEMS, 2019; 13 (4)

To further improve fuel consumption performance of hybrid electric vehicles (HEVs) running on commute route in the face of time-varying traffic information, this paper investigates a real-time energy management strategy based on the adaptive equivalent consumption minimization strategy (A-ECMS) framework with traffic information recognition. The proposed management strategy integrates the global near optimization and the real-time performance. The simple traffic recognition is constructed by utilising k-means clustering algorithm to deal with the historical traffic data to form four clusters. The adaptive equivalence factor of the A-ECMS is designed as a three-dimensional mapping on each cluster and the system states by employing stochastic dynamic programming (SDP) policy iteration to solve offline the stochastic optimal control problem formulated by each cluster statistical characteristic. In real-time energy management controller online, the instantaneous power split is performed by the ECMS with a proper equivalent factor, which is obtained from mappings according to the cluster recognised by the current traffic situation and the state-of-charge (SOC). The effectiveness of the designed control strategy is verified by the simulation test conducted on GT-suite HEV simulator over real driving cycles.

IF:2.05

Performance Analysis of Relay Selection in Cooperative NOMA Networks

期刊: IEEE COMMUNICATIONS LETTERS, 2019; 23 (4)

In this letter, we investigate the relay selection (RS) problem in cooperative non-orthogonal multiple access networks, where one base station communicates with two paired users with different priorities through multiple relays. A novel twostage RS scheme is proposed to satisfy the quality-of-service requirements of both users by considering the employment of the instantaneous channel state information in the user ordering. We derive a closed-form expression of the outage probability and obtain the diversity order for the proposed scheme. The simulation results show that the proposed RS scheme achieves a lower outage probability than the existing RS schemes.

IF:3.46

Pedestrian Injury Severities in Pedestrian-Vehicle Crashes and the Partial Proportional Odds Logit Model: Accounting for Age Difference

期刊: TRANSPORTATION RESEARCH RECORD, 2019; 2673 (5)

This study investigates factors that significantly contribute to the severity of pedestrian injuries resulting from pedestrian-vehicle crashes. Multinomial logit (MNL) models, mixed logit (ML) models, and ordered logit/probit models have been widely used in modeling crash injury severity, including pedestrian injury severity in pedestrian-vehicle crashes. However, both MNL and ML models treat injury severity levels as non-ordered, ignoring the inherent hierarchical nature of crash injury severities, and the data used in ordered logit models need to be strictly subjected to the proportional odds (PO) assumption. In this study, a partial proportional odds (PPO) logit model approach is employed to explore the issues of pedestrian safety associated with each age group: young (aged under 24), middle-aged (aged 25-55), and older pedestrians (aged over 55). Data used in this study are police-reported pedestrian crash data collected from 2007 to 2014 in North Carolina. A variety of motorist, pedestrian, environmental, and roadway characteristics are inspected. Results from likelihood ratio tests statistically show the better performance of developing separate injury severity models for each age group compared with estimating a single model utilizing all data. Relevant parameter estimates and associated marginal effects are used to interpret the results, followed by recommendations made in the concluding section.

IF:0.75

Direct generation of level of service maps from images using convolutional and long short-term memory networks

期刊: JOURNAL OF INTELLIGENT TRANSPORTATION SYSTEMS, 2019; 23 (3)

Congestion in transport stations could result in stampede development and deadly crush situations. Closed circuit television (CCTV) cameras enable station managers to monitor the crowd and reduce overcrowding risks. However, identifying congestion conditions is a very laborious task for a human operator who has to monitor multiple locations at the same time. This paper presents a new approach to automated image-based identification of congestion as measured by level of service (LOS), which is the most widely accepted standard for measuring congestion. Existing methods for measuring LOS based on crowd density estimation from images have the disadvantages that, crowd density cannot be estimated accurately. In addition, the calculation of flow parameters involves a complex process, and consequently these parameters are not indicative of congestion in real-time. This paper proposes a novel method based on machine learning to directly classify LOS without calculating flow parameters. In the proposed method, visual features extracted by a deep convolutional neural network are classified using a support vector machine classifier and the classification results are further refined by using a long short-term memory network. A second contribution of this research is to develop a web-based LOS map visualization platform to monitor pedestrian distribution and variation of distribution in real-time. Experimental evaluation at Flinders Street Station in Melbourne shows that this method can achieve an accuracy of 81.9% and efficiency of 0.40 seconds per frame in LOS classification using CCTV images.

IF:2.57

Different effects of Forsythia suspensa metabolites on bovine serum albumin (BSA)

期刊: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 2019; 214 ()

Forsythia suspensa metabolites have many bioactivities, such as selective immuno suppression, antioxidation, anti-hepatic injury, etc. In the present study, the interactions of the three metaboliteswith BSA have been investigated in a buffer (pH 7.40) using multi-spectroscopic techniques in combination with molecular docking methods. Two isoformers, forsythoside A and forsythoside I can statically quench BSA intrinsic fluorescence by forming the complexeswith BSA at stoichiometric ratio of 1:1 that is again proved by UV-visible absorption. During the binding, the proportion of alpha-helix in BSA increases, the microenvironment around Tryptophan 213 changes and FRET is one of the major factors to quench fluorescence. Forsythoside E forms BSA-forsythoside E complex (1:1) and thus enhances the intrinsic fluorescence of BSA. During the process, forsythoside E affects not only Tryptophan residues but also Tyrosine residues so that the conformation of BSA is consequently changed. All above binding processes are spontaneous mainly through hydrogen bonding and the hydrophobic force interaction, which is supported by docking analysis and thermodynamic parameters. In addition, three compounds do not induce BSA aggregation. These findings are beneficial to understand the detailed information of the interactions of Forsythia suspensa metabolites with BSA. (C) 2019 Published by Elsevier B.V.

IF:2.93

A comparative evaluation of the activities of thiol group and hydroxyl group in low-frequency vibrations using terahertz spectroscopy and DFT calculations

期刊: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 2019; 214 ()

Low-frequency vibrations of biomolecules governmany biological processes like allostery of proteins, binding interaction and solvation. Revealing how involved are different groups of molecules in low-frequency vibrations is of significance to understand the behaviors of biomolecules. To compare the activities of hydroxyl group and thiol group in low-frequency vibrations, we conducted THz measurements and DFT calculations of L-serine and L-cysteine. We performed quantitative analyses on their low-frequency vibrations to study their difference. Statistical analyses on the vibrational modes in our studied range suggest the thiol group shows a higher level of activity in low-frequency vibrations than hydroxyl group. (C) 2019 Elsevier B.V. All rights reserved.

IF:2.93

On the Ratio of Two Correlated Complex Gaussian Random Variables

期刊: IEEE COMMUNICATIONS LETTERS, 2019; 23 (12)

In this letter, we derive new results for the statistics of the ratio of two complex Gaussian random variables (RVs), where the numerator and denominator may have arbitrary means and are possibly correlated. Exact expressions are derived for the joint probability density function (pdf) of the real and imaginary parts, for the joint pdf of the amplitude and phase, and also for the joint characteristic function (cf) of the real and imaginary parts, which generalize the existing results. Then, we show an example application of the derived pdf to the symbol error probability (SEP) analysis for a single antenna communication system with imperfect channel state information (ICSI).

IF:3.46

Governing local sourcing practices of overseas projects for the Belt and Road Initiative: A framework and evaluation

期刊: TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW, 2019; 126 ()

A unified framework is proposed to investigate the ex-post factors of local sourcing practices in overseas projects for the Belt and Road Initiative, which includes twelve governance factors in four dimensions, i.e., coordinated adaptation, control and safeguarding, incentives and payment structure, and policies and regulations. A fuzzy Decision Making Trial and Evaluation Laboratory (DEMATEL) approach is applied to evaluate the inter-relationships among the factors. The results indicate that relational governance mechanisms such as trust building play a prominent role in implementing local sourcing practices while formal governance mechanisms such as country-level policies and regulations are the precondition for relational mechanisms.

IF:4.25

Connectedness-Aware Copy-Adaptive Routing Protocol in Intermittently Connected Networks

期刊: INTERNATIONAL JOURNAL OF WIRELESS INFORMATION NETWORKS, 2019; 26 (3)

In the intermittently connected networks where the complete paths from a source to a destination do not always exist, multi-copy forwarding is considered to be capable of providing more reliable transmission than single-copy forwarding. However, injecting too many copies into a network can cause unnecessary network resource consumption that degrades the network performance, especially if the network nodes are low-cost and resource-constrained. Therefore, copy control is a critical efficiency mechanism for the forwarding protocols in such situations. Using a preset threshold is a common copy-control mechanism used by many multi-copy forwarding protocols. The preset threshold is the maximum allowed number of copies of a packet in a network, calculated before running these protocols. It can effectively reduce the unnecessary copies and provide better performance than the protocols without using copy control. However, preset threshold makes the protocol less flexible with respect to the variations of network characteristics such as density or connectedness caused by node failures or new nodes joining. In this paper, we propose a multi-copy routing algorithm, Connectedness-Aware Copy-Adaptive Routing (CACAR) protocol, which adopts a novel copy-control mechanism. CACAR estimates the network connectedness locally and conducts the copy control and the next-hop selection based on the measured connectedness. This proposed protocol can achieve a higher delivery rate and lower latency without sacrificing the energy efficiency compared with other benchmark multi-copy routing protocols.

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