A half-car vibration model of an electric vehicle driven by rear in-wheel motors was developed using bond graph theory and the modular modeling method. Based on the bond graph model, modal analysis ...was carried out to study the vibration characteristics of the electric vehicle. To verify the effectiveness of the established model, the results were compared to ones computed on the ground of modal analysis and Newton equations. The comparison shows that the vibration model of the electric vehicle based on bond graph theory not only is able to better compute the natural frequency but also can easily determine the deformation mode, momentum mode, and other isomorphism modes and describe the dynamic characteristics of an electric vehicle driven by in-wheel motors more comprehensively than other modal analysis methods.
For in-wheel-motor-driven electric vehicles, the motor is installed in the wheel directly. Tyre runout and uneven load can cause magnet gap deformation in the motor, which will produce ...electromagnetic forces that further influence the vehicle rollover characteristics. To study the rollover characteristics, a verified 16-degree-of-freedom rollover dynamic model is introduced. Next, the vehicle rollover characteristics both with and without electromagnetic force are analyzed under conditions of the Fixed Timing Fishhook steering and grade B road excitation. The results show that the electromagnetic force has a certain effect on the load transfer and can reduce the antirollover performance of the vehicle. Therefore, the effect of the electromagnetic force on the rollover characteristic should be considered in the vehicle design. To this end, extensive analysis was conducted on the effect of the road level, vehicle speed, and the road adhesion coefficient on the vehicle rollover stability. The results indicate that vehicle rollover stability worsens when the above-mentioned factors increase, the most influential factor being the road adhesion coefficient followed by vehicle speed and road level. This paper can offer certain theory basis for the design of the in-wheel-motor-driven electric vehicles.
As the core component of in-wheel motor-driven electric vehicles, the in-wheel motor (IWM) directly affects the driving/braking performance of each driving wheel and the driving performance of the ...vehicle. The IWM operation involves a coupling of multi-fields, including the electromagnetic, temperature, flow, and mechanical fields, which influence each other. It is necessary to study coupling analysis methods to obtain accurate and consistent results. In this paper, a 15 kW in-wheel motor is taken as the research object. Based on the finite element model of the IWM, the coupling factors between the electromagnetic and temperature field, and the influence trend of coupling factors on the two fields are investigated. On this basis, considering the strong coupling factors obtained from the above analysis, the unidirectional coupling and bidirectional coupling analysis methods are used to analyze the electromagnetic–temperature characteristics of the IWM, and the comparative results between the two methods are discussed. It was found that the results showed the temperature of the IWM calculated by the bidirectional coupling method was higher than that obtained by the unidirectional coupling analysis method. The maximum temperature of stator windings calculated by bidirectional coupling was 7.1% higher than that calculated by unidirectional coupling analysis, and the effect on the relative difference of torque could reach 7.4%. Bidirectional coupling can more accurately reflect the variation of variables in the fields and the prediction of motor performance in the process of motor operation. The progress made in the electromagnetic–temperature coupled analysis method can provide a theoretical basis and useful ideas for the multi-fields coupling analysis of IWMs.
Prenatal inflammation is a risk factor for necrotizing enterocolitis (NEC), and it increases intestinal injury in a rat NEC model. We previously showed that maldevelopment of the intestinal ...microvasculature and lack of vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) signaling play a role in experimental NEC. However, whether prenatal inflammation affects the intestinal microvasculature remains unknown. In this study, mouse dams were injected intraperitoneally with lipopolysaccharide (LPS) or saline at
. Neonatal intestinal microvasculature density, endothelial cell proliferation, and intestinal VEGF-A and VEGFR2 proteins were assessed in vivo. Maternal and fetal serum TNF concentrations were measured by ELISA. The impact of TNF on the neonatal intestinal microvasculature was examined in vitro and in vivo, and we determined whether prenatal LPS injection exacerbates experimental NEC via TNF. Here we found that prenatal LPS injection significantly decreased intestinal microvascular density, endothelial cell proliferation, and VEGF and VEGFR2 protein expression in neonatal mice. Prenatal LPS injection increased maternal and fetal serum levels of TNF. TNF decreased VEGFR2 protein in vitro in neonatal endothelial cells. Postnatal TNF administration in vivo decreased intestinal microvasculature density, endothelial cell proliferation, and VEGF and VEGFR2 protein expression and increased the incidence of severe NEC. These effects were ameliorated by stabilizing hypoxia-inducible factor-1α, the master regulator of VEGF. Furthermore, prenatal LPS injection significantly increased the incidence of severe NEC in our model, and the effect was dependent on endogenous TNF. Our study suggests that prenatal inflammation increases the susceptibility to NEC, downregulates intestinal VEGFR2 signaling, and affects perinatal intestinal microvascular development via a TNF mechanism.
This report provides new evidence that maternal inflammation decreases neonatal intestinal VEGF receptor 2 signaling and endothelial cell proliferation, impairs intestinal microvascular development, and predisposes neonatal mouse pups to necrotizing enterocolitis (NEC) through inflammatory cytokines such as TNF. Our data suggest that alteration of intestinal microvascular development may be a key mechanism by which premature infants exposed to prenatal inflammation are at risk for NEC and preserving the VEGF/VEGF receptor 2 signaling pathway may help prevent NEC development.
For an in-wheel motor driving system with rubber bushings, the driving motor is integrated into the wheel. A magnet gap deformation of the motor will be inevitably caused by the road excitation, ...which will produce an unbalanced electromagnetic force and influence the power-train vibration. Furthermore, the rim is flexibly connected to the motor rotor by rubber bushings, and a strong coupling and nonlinear vibration of the power-train in all directions can be demonstrated under the electromagnetic excitations. Thus, a 14-degree-of-freedom coupling vibration model of the power-train is first developed for the in-wheel motor driving system with rubber bushings, including the bushing and bearing models. Then, the mathematical model is deduced using a Lagrangian approach. Finally, based on the model, a coupling vibration analysis is conducted under different electromagnetic force excitations. The results indicate that there are coupling vibration components in the torsional direction, except the one-time rotating frequency; however, in the bending direction, the vibration response includes a one-time rotating frequency component and an excitation frequency component of the electromagnetic force. Furthermore, the results indicate that the bushing plays an important role in reducing the power-train vibration, which has a positive effect on the improving vehicle dynamics.
OBJECTIVE： To assess the clinical effectiveness and safety of injections of ginkgo （GI） combined with Western Medicine （WM） for cerebral infarction （C/）. METHODS; Randomized controlled trials （RCTs） ...of C/treated by GI were searched in China National Knowledge Infrastructure Database, Wanfang, China Science and Technology Journal Database, Web of Science, Cochrane library, Embase, PubMed and Chinese Biomedical Literature Database, with the publication data no later than April, 2016. The Co- chrane risk of bias method was used to evaluate the methodological quality of the RCTs. The data were analyzed by Review Manager 5.3, Stata 13.0, and WinBUGS 14 software.RESULTS： Totally 37 RCTs involving 4330 patients were included. By direct comparison, the results of GI group were significantly superior to the routine WM group in the total effective rates OR = 3.61, 95% CI （2.93, 4.44）, P 〈 0.0001, the neural function defect score （NFDS） MD = - 4.39, 95% CI （- 5.47, - 3.32）, P 〈 0.0001. Network Meta-analysis （NMA） results showed that, between S GIs in efficacy, the difference comparing ginaton injections （GbE） to ginkgo-dipyidamolum injections （GD） OR = 1.74, 95% CI （0.73, 3.65）, shuxuening injections （SXN） OR = 1.06, 95% CI （0.609, 1.697） or ginkgolides in- jections （GK） OR = 4.711, 95% CI （1.178, 13.21） reach statistical significance; the difference compar- ing GD to GK reach statistical significance OR = 2.791, 95% CI （0.866, 6.908）; the difference com- paring SXN to GK reach statistical significance OR = 4.537, 95% CI （1.203, 12.41）. Besides, there was no difference between 4 GIs in NFDS. Proba- bility ranking result showed a great possibility for GK Surface under the Cumulative Ranking curve （SUCRA） = 80.3% in improving the total effective rates, which were followed by GD （SUCRA = 73.34%）, SXN （SUCRA = 46.59%）, GbE （SUCRA = 45.46%）, floium ginkgo extract and tertram ethy- pyrazine sodium chloride injections （FT） （SU- CRA = 35.64%）. However, GK （SUCRA = 80.3%） or GbE （SUCRA = 69.4%） was better than other GIs in reducing NFDS.GK ＋ WM is the best treatment measures to reduce NFDS in cerebral infarction, which were followed by SXN ＋ WM （SUCRA = 51.6%）, GD ＋ WM （SUCRA = 48.1%）. CONCLUSION： GIs was more effectiveness on CI than the routine Western Medicine. But based on the limitations of the study, more high-quality ran- domized controlled trials will be necessary.
The COVID-19 pandemic poses a great challenge to healthcare. We aimed to investigate the impact of COVID-19 on the healthcare of patients with inflammatory bowel disease (IBD) in epicenter and ...non-epicenter areas.
Patients with IBD from Hubei province (the epicenter of COVID-19) and Guangdong province (a non-epicenter area), China were surveyed during the pandemic. The questionnaire included change of medications (steroids, immunomodulators, and biologics), procedures (lab tests, endoscopy, and elective surgery), and healthcare mode (standard healthcare vs. telemedicine) during 1 month before and after the outbreak of COVID-19.
In total, 324 IBD patients from Guangdong province (non-epicenter) and 149 from Hubei province (epicenter) completed the questionnaire with comparable demographic characteristics. Compared to patients in Guangdong province (non-epicenter), significantly more patients in Hubei (epicenter) had delayed lab tests/endoscopy procedures 61.1% (91/149) vs. 25.3% (82/324),
< 0.001, drug withdrawal 28.6% (43/149) vs. 9.3% (30/324),
< 0.001, delayed biologics infusions 60.4% (90/149) vs. 19.1% (62/324),
< 0.001, and postponed elective surgery 16.1% (24/149) vs. 3.7% (12/324),
< 0.001. There was an increased use of telemedicine after the outbreak compared to before the outbreak in Hubei province 38.9% (58/149) vs. 15.4% (23/149),
< 0.001, while such a significant increase was not observed in Guangdong province 21.9% (71/324) vs. 18.8% (61/324),
= 0.38. Approximately two-thirds of IBD patients from both sites agreed that telemedicine should be increasingly used in future medical care.
Our patient-based survey study in a real-world setting showed that COVID-19 resulted in a great impact on the healthcare of patients with IBD, and such an impact was more obvious in the epicenter compared to the non-epicenter area of COVID-19. Telemedicine offers a good solution to counteract the challenges in an unprecedented situation such as COVID-19.
During the construction of precast concrete (PC) structures, concrete composite slabs are commonly used, employing PC planks with lattice girders as permanent formwork to enhance assembly efficiency ...while ensuring structural performance. However, traditional PC planks suffer from heavy weight and susceptibility to cracking, adversely affecting construction efficiency and quality. This paper proposes the incorporation of ultra-lightweight engineered cementitious composite (ULECC) into PC planks. The research aims to investigate the flexural behavior of precast ULECC planks with lattice girders during the construction stage. Four-point bending tests were conducted to study the effects of lattice girders and ULECC layer. The introduction of ULECC reduced the self-weight of precast planks by 24%, while resulting in a decrease in strength and stiffness due to ULECC's lower elastic modulus. Remarkably, precast ULECC planks exhibited excellent crack width control. Even at a deflection-span ratio of approximately 4%, precast ULECC planks were capable of maintaining crack widths below 0.2 mm. The combination of ULECC and lattice girders significantly improved the structural performance of precast ULECC planks, allowing them to meet construction requirements without requiring temporary support.
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