Data Filtering Method for Intelligent Vehicle Shared Autonomy Based on a Dynamic Time Warping Algorithm.

Big data already covers intelligent vehicles and is driving the autonomous driving industry's transformation. However, the large amounts of driving data generated will result in complex issues and a huge workload for the test and verification processes of an autonomous driving system. Only effective and precise data extraction and recording aimed at the challenges of low efficiency, poor quality, and a long-time limit for traditional data acquisition can substantially reduce the algorithm development cycle. Based on the premise of driver-dominated vehicle movement, the virtual decision-making of autonomous driving systems under the accompanying state was considered as a reference. Based on a dynamic time warping algorithm and forming a data filtering approach under a dynamic time window, an automatic trigger recording control model for human-vehicle difference feature data was suggested. In this method, the data dimension was minimized, and the efficiency of the data mining was improved. The experimental findings showed that the suggested model decreased recorded invalid data by 75.35% on average and saved about 2.65 TB of data storage space per hour. Compared with industrial-grade methods, it saves an average of 307 GB of storage space per hour.

Highly Anisotropic Thermal Conductivity of Three-Dimensional Printed Boron Nitride-Filled Thermoplastic Polyurethane Composites: Effects of Size, Orientation, Viscosity, and Voids.

Extrusion-based three-dimensional (3D) printing techniques usually exhibit anisotropic thermal, mechanical, and electric properties due to the shearing-induced alignment during extrusion. However, the transformation from the extrusion to stacking process is always neglected and its influence on the final properties remains ambiguous. In this work, we adopt two different sized boron nitride (BN) sheets, namely, small-sized BN (S-BN) and large-sized BN (L-BN), to explore their impact on the orientation degree, morphology, and final anisotropic thermal conductivity (TC) of thermoplastic polyurethane (TPU) composites by fused deposition modeling. The transformation from one-dimensional axial alignment in the extruded filament to two-dimensional alignment (horizontal and vertical alignment) in the stacking filament of BN sheets is observed, and its impact on anisotropic TC in three directions is clarified. It is found that L-BN/TPU composites show a high TC of 6.45 W m-1 K-1 at 60 wt % BN content along the printing direction, while at a lower content (<40 wt %), S-BN/TPU composites exhibit a higher TC than L-BN/TPU composites. Effects of orientation, viscosity, and voids are comprehensively considered to elucidate such differences. Finally, heat dissipation tests demonstrate the great potential of 3D printed BN/TPU composites to be used in thermal management applications.

Highly Thermally Conductive 3D Printed Graphene Filled Polymer Composites for Scalable Thermal Management Applications.

Efficient thermal transportation in a preferred direction is highly favorable for thermal management issues. The combination of 3D printing and two-dimensional (2D) materials such as graphene, BN, and so on enables infinite possibilities for hierarchically aligned structure programming. In this work, we report the formation of the asymmetrically aligned structure of graphene filled thermoplastic polyurethane (TPU) composites during 3D printing process. The as-printed vertically aligned structure demonstrates a through-plane thermal conductivity (TC) up to 12 W m-1 K-1 at 45 wt % graphene content, which is ∼8 times of that of a horizontally printed structure and surpasses many of the traditional particle reinforced polymer composites. The superior TC is mainly attributed to the anisotropic structure design that benefited from the preferable degree of orientation of graphene and the multiscale dense structure realized by finely controlling the printing parameters. Finite element method (FEM) confirms the essential impact of anisotropic TC design for highly thermal conductive composites. This study provides an effective way to develop 3D printed graphene-based polymer composites for scalable thermal-related applications such as battery thermal management, electric packaging, and so on.

Chain dynamics and crystalline network structure of poly[R-3-hydroxybutyrate-co-4-hydroxybutyrate] as revealed by solid-state NMR.

The chain dynamics and crystalline network structure of poly[R-3-hydroxybutyrate-co-4-hydroxybutyrate] (P(3HB-co-4HB)) were systematically investigated by the combination of various solid-state NMR techniques. High-resolution 13C cross-polarization (CP) and direct-polarization (DP) MAS with selective recycle delay times were first used to check the presence or absence of the 4HB unit in the crystalline domain. The results show that the 4HB unit is excluded from the crystalline domain. Afterward, 1H MAS Nuclear Overhauser Effect Spectroscopy (NOESY) with different mixing times was used, which shows that no micro-phase separation exists in the amorphous domain. 1H magic-sandwich-echo (MSE)-FID at elevated temperature shows the absence of motions on a timescale of 100 µs and below in the crystalline domain, as evidenced by the invariant second moment M2 of the proton line shape. Finally, the crystalline based network density was characterized directly by magic and polarization echo (MAPE)-double quantum (DQ) NMR, which shows a significant decreasing tendency after 80 °C. Such a decreasing crystalline network density, together with the reduced relaxation time, results in the significant decrement of the maximum stretch ratio and modulus in the high-temperature region.

Global Evidence of Temperature Acclimation of COVID-19 D614G Linage.

The novel D614G linage is becoming the dominating species of SARS-CoV-2. The impact of meteorological and geographical factors on SARS-CoV-2 pandemic are presently not well understood. This research article presents a retrospective case series. Pandemic and meteorological data from 30 countries and 49 states from USA are collected as of June 10th, 2020. The primary outcome are the coefficients of correlations between meteorological factors and pandemic data. Hierarchical clustering analysis are used on SARS-CoV-2 genome, meteorological factors, and pandemic. Disseminating velocity of SARS-CoV-2 is negatively correlated with average temperature in majority of included countries and states from USA. Proportion of the GR clade is positively associated with temperature, but is negatively correlated with altitude in countries-set. Virus disseminating velocities in states from cluster A (Overwhelming proportion of G + GR + GH clades, GH > 60%) and C (Overwhelming proportion of G + GR + GH clades, G 20-30%) both has negative correlations with temperature, while cluster C has more significant negative correlation than cluster A. Climate and geographical environment are revealed to affect virus spreading. GH and GR clades of SARS-CoV-2 are probably acquiring higher temperature tolerance, while G clade may retain high temperature intolerance.

Manipulation of Chain Entanglement and Crystal Networks of Biodegradable Poly(butylene adipate-co-butylene terephthalate) During Film Blowing through the Addition of a Chain Extender: An In Situ Synchrotron Radiation X-ray Scattering Study.

One prerequisite for the large-scale application of biodegradable polymers is the manipulation of macroscopic performances of commercially available biopolymers during processing according to different real service requirements. Herein, the microstructural evolution of poly(butylene adipate-co-butylene terephthalate) (PBAT) modified by chain extender during film blowing was investigated by in situ synchrotron radiation X-ray scattering to unveil the origin of different performances. The chain dynamics difference induced by the chain extender was first characterized by the rheological measurement and 1H Multiple Quantum (MQ) NMR. It shows that the terminal relaxation is significantly slowed down, while the locally segmental dynamics is not apparently changed. With the assistance of the custom-built film blowing apparatus, the microstructure right above the die exit (D = 13-165 mm) was in situ, simultaneously captured by small- and wide-angle scattering (SAXS/WAXS), where four distinct regimes can be defined. Only the PBAT melt signals are found in regime I, whereas the formation of the mesomorphic domains as shown by the SAXS streaks appearing in regime II. The crystal shows up in regime III, where the WAXS signal appears. A dramatic increment of the crystallinity is found in regime III, which contributes to the continuous increasing bubble modulus with the formation of the crystal-based network. Such a crystal-based network is filled with crystals in regime IV, where the diameter of the PBAT bubble remains constant. The addition of the chain extender is found to significantly influence the structural evolution within different regimes. These dynamics and structure information could supply general guidance for bubble stability improvement and modification of macroscopic performances of biodegradable polymer products.

Preparation of Polyethylene and Ethylene/Methacrylic Acid Copolymer Blend Films with Tunable Surface Properties through Manipulating Processing Parameters during Film Blowing.

Polymer films based on polyethylene (PE) and ionomer ethylene/methacrylic acid (EMAA) copolymer blend were prepared by film blowing, whose surface properties were tuned by varying processing parameters, i.e., take up ratio (TUR). Blends of PE/EMAA copolymer were firstly prepared by the melt-mixing method, before being further blown to films. The wettability of the film was investigated by measuring the contact angle/water-film encounter time, and optical properties, i.e., the haze and transmittance. The wettability was found to be enhanced with the increase of TUR. So too was the haze, while the transmittance was found to be almost independent of TUR. The XPS and AFM results directly show the increasing polar functional groups (-COO-) on the surface and roughness with increasing TUR. Further analysis of the 2D SAXS and WAXS unveiled the origin of the invariant transmittance, which resulted from the minor change of the crystallinity and the monotonic increase of the haze, with TUR resulting from the evolution of crystal orientation. In addition to other post-modification methods, the current study provides an alternative route to prepare large-scale PE films as the template for the advanced potential applications, i.e., covering in the layer of roof, the privacy of protective windows, and multitudes of packaging.

Heterologous expression of two Aspergillus niger feruloyl esterases in Trichoderma reesei for the production of ferulic acid from wheat bran.

Feruloyl esterase (FAE)-encoding genes AnfaeA and AnfaeB were isolated from Aspergillus niger 0913. For overexpression of the two genes in Trichoderma reesei, constitutive and inductive expression plasmids were constructed based on parental plasmid pAg1-H3. The constructed plasmids contained AnfaeA or AnfaeB gene under the control of glyceraldehyde-3-phosphate dehydrogenase A gene (gpdA) promoter (from A. nidulans) or cellobiohydrolases I (cbh I) gene promoter (from T. reesei), and cbh I terminator from T. reesei. The target plasmids were transferred into T. reesei D-86271 (Rut-C30) by Agrobacterium tumefaciens-mediated transformation (ATMT), respectively. A high level of feruloyl esterase was produced by the recombinant fungal strains under solid-state fermentation, and the cbh I promoter was more efficient than the gpdA promoter in the expression of AnfaeA. The optimum temperatures and pH values were 50 °C and 5.0 for AnFAEA, and 35 °C and 6.0 for AnFAEB. The maximum production levels were 20.69 U/gsd for AnFAEA and 15.08 U/gsd for AnFAEB. The recombinant fungal enzyme systems could release 62.9% (for AnFAEA) and 52.2% (for AnFAEB) of total ferulic acids from de-starched wheat bran, which was higher than the 46.3% releasing efficiency of A. niger 0913. The supplement of xylanase from T. longibrachiatum in the enzymatic hydrolysis led to a small increment of the ferulic acids release.