RESUMEN
With the ongoing promotion and adoption of electric vehicles, intelligent and connected technologies have been continuously advancing. Electrical control systems implemented in electric vehicles have emerged as a critical research direction. Various drive-by-wire chassis systems, including drive-by-wire driving and braking systems and steer-by-wire systems, are extensively employed in vehicles. Concurrently, unavoidable issues such as conflicting control system objectives and execution system interference emerge, positioning integrated chassis control as an effective solution to these challenges. This paper proposes a model predictive control-based longitudinal dynamics integrated chassis control system for pure electric commercial vehicles equipped with electro-mechanical brake (EMB) systems, centralized drive, and distributed braking. This system integrates acceleration slip regulation (ASR), a braking force distribution system, an anti-lock braking system (ABS), and a direct yaw moment control system (DYC). This paper first analyzes and models the key components of the vehicle. Then, based on model predictive control (MPC), it develops a controller model for integrated stability with double-layer torque distribution. The required driving and braking torque for each wheel are calculated according to the actual and desired motion states of the vehicle and applied to the corresponding actuators. Finally, the effectiveness of this strategy is verified through simulation results from Matlab/Simulink. The simulation shows that the braking deceleration of the braking condition is increased by 32% on average, and the braking distance is reduced by 15%. The driving condition can enter the smooth driving faster, and the time is reduced by 1.5 s~5 s. The lateral stability parameters are also very much improved compared with the uncontrolled vehicles.
RESUMEN
The direct copolymerization of p-tosyl isocyanate (TSI) with epoxides, initiated by onium salts in the presence of trialkylborane, to produce polyurethanes is reported. The rate of copolymerization and the (regio)selectivity were investigated in relation to the trialkylborane and the initiator used. Under optimized conditions such copolymerizations have been successfully performed for a wide range of epoxides, including ethylene oxide, propylene oxide, 1-octene oxide, cyclohexene oxide, and allyl glycidyl ether. These copolymerizations afford a new category of polyurethanes, clear of side products such as cyclic oxazolidinone, isocyanurate, and poly(isocyanate) linkages. The experimental conditions used in this work are compatible with those for the organocatalytic (co)polymerization of other oxygenated monomers and CO2 , holding the potential for their terpolymerization with p-tosyl isocyanate and the development of new materials with unprecedented properties.
RESUMEN
Various oxirane monomers including alkyl ether or allyl-substituted ones such as 1-butene oxide, 1-hexene oxide, 1-octene oxide, butyl glycidyl ether, allyl glycidyl ether, and 2-ethylhexyl glycidyl ether were anionically copolymerized with CO2 into polycarbonates using onium salts as initiator in the presence of triethylborane. All copolymerizations exhibited a "living" character, and the monomer consumption was monitored by in situ Fourier-transform infrared spectroscopy. The various polycarbonate samples obtained were characterized by 1H NMR, GPC, and differential scanning calorimetry. In a second step, all-polycarbonate triblock copolymers demonstrating elastomeric behavior were obtained in one pot by sequential copolymerization of CO2 with two different epoxides, using a difunctional initiator. 1-Octene oxide was first copolymerized with CO2 to form the central soft poly(octene carbonate) block which was flanked by two external rigid poly(cyclohexene carbonate) blocks obtained through subsequent copolymerization of cyclohexene oxide with CO2. Upon varying the ratio of 1-octene oxide to cyclohexene oxide and their respective ratios to the initiator, three all-polycarbonate triblock samples were prepared with molar masses of about 350 kg/mol and 22, 26, and 29 mol % hard block content, respectively. The resulting triblock copolymers were analyzed using 1H NMR, GPC, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy. All three samples demonstrated typical elastomeric behavior characterized by a high elongation at break and ultimate tensile strength in the same range as those of other natural and synthetic rubbers, in particular those used in applications such as tissue engineering.
RESUMEN
Whatever the chemistry used for the synthesis of aliphatic polycarbonates, in particular, those of high molar mass, the adventitious presence of water leads to bimodal GPC traces and affords polycarbonate samples of uncontrolled and unpredictable molar masses. It appears that among all reagents used in the copolymerization of CO2 and epoxides, CO2 is the most difficult one to dry. To address this issue, triisobutylaluminum (TiBA) was employed in this work to dry CO2 through a bubbling method; its drying capability was investigated in the context of the copolymerization of CO2 with epoxides initiated by onium chloride in the presence of triethylborane (TEB). It was then compared to the efficiency of other already reported drying agents such as phosphorus pentoxide, molecular sieves and commercially available CO2 purifiers. With TiBA-dried CO2, its copolymerizations respectively with propylene oxide (PO) and cyclohexene oxide (CHO) could be successfully achieved in a wide range of degrees of polymerization (DP), with the value of DP as high as 16000. Diblock copolymers poly(propylene carbonate-b-cyclohexene carbonate) (PPC-b-PCHC) could also be prepared through sequential addition of epoxide monomers. The polycarbonates obtained under the conditions were all well-defined as characterized by NMR, GPC, triple detector-GPC, and differential scanning calorimetry (DSC).
RESUMEN
The influence of ß-cyclodextrin-epichlorohydrin (ß-CD-EP) polymers on the improvement of the solubility and antifungal activity of carbendazim has been investigated. Meanwhile, the potential of the chitosan and ß-CD-EP composite film used as a plant healthcare material for carbendazim-controlled release to protect rape against Sclerotinia sclerotiorum (Lib.) de Bary has been evaluated. ß-CD-EP-1 and 2 (ß-CD content, 750 mg/g and 440 mg/g, respectively) were found to significantly improve the solubility of the guest molecule carbendazim (17.9 and 18.5 times, respectively) and the 1:1 stoichiometry of the host-guest was confirmed by the Job's plot. A slight synergism was observed for the ß-CD-EP/carbendazim complex against S. sclerotiorum (Lib.) de Bary, indicating an enhancement to the bioavailability of carbendazim. The in vitro release studies revealed that ß-CD-EP polymers could efficiently modulate carbendazim release behaviors, such as the release retard and rate. The in vivo efficacy experiments demonstrated that the ß-CD-EP/carbendazim and chitosan composite film could significantly prolong the effective duration of carbendazim at a concentration of 100 µg/mL compared with spraying carbendazim at 500 µg/mL. Thereby, a highly useful and strategic concept in plant disease control by a plant healthcare material-the chitosan and polymeric ß-CD-EP composite film-is provided, which could also serve as a concept for related plant diseases.
RESUMEN
High durability of low-k value is a desired property for dielectrics serving under humid conditions, because absorbing a small amount of moisture by the material can considerably increase the k value so as to result in function deterioration. Aiming to develop a dielectric polymer with superior durability of low-k value and high thermal stability, a perfluorocyclobutyl (PFCB) biphenyl ether-based polyimide, PFCBBPPI, was synthesized. This polymer possesses a Tg of 310.3 °C and a 5% weight loss temperature of 510.5 °C. PFCBBBPPI exhibited an extremely low water uptake of 0.065 ± 0.018%, representing the best water resistance in polyimides. The increasing percentage in k value was below 2% for PFCBBPPI film exposed to moisture under various humidity conditions for 6 h. PFCBBPPI film equilibrated at 75% R.H. for 2 weeks still kept its k value below 2.50, remarkably outperforming the Kapton film. The remarkable water resistance and resulting high durability of low-k property displayed by PFCBBPPI are originated from the hydrophobic nature and small free volume fraction of the polymer, as confirmed by contact angle test and positron annihilation lifetime spectroscopy results. The outstanding moisture resistance and overall performance of PFCBBPPI make it a suitable candidate for dielectric applications under both dry and humid conditions.