Incidence and transfer behaviors of high-order hot judder in passenger cars

As one of the brake-induced noises and vibrations, hot judder is forced vibration, which is caused by unevenness of the brake disc due to the thermal mechanical interactions in wheel brakes. Brake disc unevenness is normally described and evaluated as the Disc Thickness Variation (DTV) and the disc’ Lateral Run-Out (LRO). DTV and LRO gener-ate Brake Pressure Variation (BPV) and Brake Torque Variation (BTV) in wheel brakes, which are transmitted to the driver and perceived by the driver as the brake pedal pulsa-tion, the steering wheel oscillation, the car body vibrations, and low-frequency drone noises inside a vehicle. Hot judder is characterized by hot spots on the disc surfaces. The frequency of hot judder is dependent on the wheel rotational speed, showing order behaviors. The num-ber of hot spots generally corresponds to the dominant order of hot judder. In the last decades, most of the hot judder tests have been carried out with brake dynamometers, and high numbers (typically around 10) of hot spots were found in the majority of the tests. The generation and development mechanisms of the high dominant order have been almost the exclusive focus of current hot judder researches. However, the influ-ences of the vibrations and noises (with higher frequencies compared with the low-order cold judder) caused by high-order hot judder on the driver’s subjective perception have been still not clarified. That is to say, it is still unknown in which form and under which conditions, the high-order hot judder can be transmitted to and perceived by the driver, and thus causing customer complaints. A top-down approach is used in order to investigate the influences of high-order judder on driver’s perception with respect to two aspects: the incidence of high-order hot jud-der in vehicle tests and the drivers’ perception of high-order hot judder. The first aspect is mainly investigated by studying the transferability of dynamometer tests to vehicle tests and by identifying the incidence of high-order hot judder in production brakes. Specifically, identical brakes from one front brake and one rear brake are separately tested with a brake dynamometer and through vehicle tests by means of road tests and chassis dynamometer tests, and all brakes of four production passengers are identified with accelerometers attached on the brake caliper and the caliper bracket. The perception of high-order hot judder is chiefly studied by investigating its transfer behaviors. Global transfer functions from BPV/BTV to the selected driver interface quantities (brake pedal pulsation, steering wheel oscillation, seat track vibrations, and vehicle interior drone noise) are defined, which establish the links between the hot judder intensity in the wheel brake and the intensity at the driver interface. In order to identify the transfer functions with a high signal-noise-ratio and better reproducibility, a novel testing method is adopted: vehicle tests with brake discs that are artificially modi-fied with the desired surface shapes simulating the high-order DTV/LRO. Altogether three vehicles with seven different modified discs are tested. Two critical levels of drone noise (60 and 80 dB(A)) are selected according to the general vehicle total noise level and the human’s perception characteristics of sound. The perception threshold values of the driver interface vibrations are obtained through regression analysis between their subjective ratings and objective measurements. Based on the critical drone noise levels and the threshold values of vibrations, as well as the global transfer functions, threshold values of BPV and BTV for perceiving the high-order judder are computed. Concerning the incidence of high-order judder, both the dominant order and the thermal increases of BTV and BPV for the dominant order showed great discrepancies in differ-ent test types (e.g. brake dynamometer or vehicle, drag braking application with con-stant velocity and constant pressure/torque or stop braking application with decreasing velocity and constant deceleration/pressure). Hot judder behaviors in the brake dyna-mometer test were not transferable to the vehicle tests. Besides, no evident high-order hot judder has been identified in all the brakes of the four passenger cars. Generally, hot judder seems to be more likely to be excited at the brake dynamometer than in the vehi-cles. Therefore, brake dynamometer test is still appropriate for detecting hot judder in the early phase of brake development, and thus preventing its occurrence in the vehicle. Regarding the driver’s perception, the drone noise is the most probable reason leading to customer complaints, since higher than 100 Hz less than 10 Nm BTV is required to perceive the drone noise and 50 Nm BTV can already result in unacceptable drone noise. The driver is less sensitive to the vibrations caused by high-order judder. Roughly at least 20 Nm BTV or 2.5 bar BPV is needed for perceiving the vibrations, and the perception is most possibly due to the steering wheel oscillation or the vertical vehicle vibration. Moreover, some resonances in the transfer paths play a significant role in the high-order judder transmission. Although the investigations in this work are limited to three vehicles, the practical significance of high-order hot judder on the driver’s percep-tion is revealed for the first time. With these results, the impact of the measured BTV and BPV of hot judder, e.g. in the brake dynamometer tests, can be assessed. Combining these results, the most effective and efficient way to mitigate the high-order hot judder would be reducing its occurrences in the wheel brakes and diminishing the prominent resonances in the transfer paths

Incidence and transfer behaviors of high-order hot judder in passenger cars

As one of the brake-induced noises and vibrations, hot judder is forced vibration, which is caused by unevenness of the brake disc due to the thermal mechanical interactions in wheel brakes. Brake disc unevenness is normally described and evaluated as the Disc Thickness Variation (DTV) and the disc’ Lateral Run-Out (LRO). DTV and LRO gener-ate Brake Pressure Variation (BPV) and Brake Torque Variation (BTV) in wheel brakes, which are transmitted to the driver and perceived by the driver as the brake pedal pulsa-tion, the steering wheel oscillation, the car body vibrations, and low-frequency drone noises inside a vehicle. Hot judder is characterized by hot spots on the disc surfaces. The frequency of hot judder is dependent on the wheel rotational speed, showing order behaviors. The num-ber of hot spots generally corresponds to the dominant order of hot judder. In the last decades, most of the hot judder tests have been carried out with brake dynamometers, and high numbers (typically around 10) of hot spots were found in the majority of the tests. The generation and development mechanisms of the high dominant order have been almost the exclusive focus of current hot judder researches. However, the influ-ences of the vibrations and noises (with higher frequencies compared with the low-order cold judder) caused by high-order hot judder on the driver’s subjective perception have been still not clarified. That is to say, it is still unknown in which form and under which conditions, the high-order hot judder can be transmitted to and perceived by the driver, and thus causing customer complaints. A top-down approach is used in order to investigate the influences of high-order judder on driver’s perception with respect to two aspects: the incidence of high-order hot jud-der in vehicle tests and the drivers’ perception of high-order hot judder. The first aspect is mainly investigated by studying the transferability of dynamometer tests to vehicle tests and by identifying the incidence of high-order hot judder in production brakes. Specifically, identical brakes from one front brake and one rear brake are separately tested with a brake dynamometer and through vehicle tests by means of road tests and chassis dynamometer tests, and all brakes of four production passengers are identified with accelerometers attached on the brake caliper and the caliper bracket. The perception of high-order hot judder is chiefly studied by investigating its transfer behaviors. Global transfer functions from BPV/BTV to the selected driver interface quantities (brake pedal pulsation, steering wheel oscillation, seat track vibrations, and vehicle interior drone noise) are defined, which establish the links between the hot judder intensity in the wheel brake and the intensity at the driver interface. In order to identify the transfer functions with a high signal-noise-ratio and better reproducibility, a novel testing method is adopted: vehicle tests with brake discs that are artificially modi-fied with the desired surface shapes simulating the high-order DTV/LRO. Altogether three vehicles with seven different modified discs are tested. Two critical levels of drone noise (60 and 80 dB(A)) are selected according to the general vehicle total noise level and the human’s perception characteristics of sound. The perception threshold values of the driver interface vibrations are obtained through regression analysis between their subjective ratings and objective measurements. Based on the critical drone noise levels and the threshold values of vibrations, as well as the global transfer functions, threshold values of BPV and BTV for perceiving the high-order judder are computed. Concerning the incidence of high-order judder, both the dominant order and the thermal increases of BTV and BPV for the dominant order showed great discrepancies in differ-ent test types (e.g. brake dynamometer or vehicle, drag braking application with con-stant velocity and constant pressure/torque or stop braking application with decreasing velocity and constant deceleration/pressure). Hot judder behaviors in the brake dyna-mometer test were not transferable to the vehicle tests. Besides, no evident high-order hot judder has been identified in all the brakes of the four passenger cars. Generally, hot judder seems to be more likely to be excited at the brake dynamometer than in the vehi-cles. Therefore, brake dynamometer test is still appropriate for detecting hot judder in the early phase of brake development, and thus preventing its occurrence in the vehicle. Regarding the driver’s perception, the drone noise is the most probable reason leading to customer complaints, since higher than 100 Hz less than 10 Nm BTV is required to perceive the drone noise and 50 Nm BTV can already result in unacceptable drone noise. The driver is less sensitive to the vibrations caused by high-order judder. Roughly at least 20 Nm BTV or 2.5 bar BPV is needed for perceiving the vibrations, and the perception is most possibly due to the steering wheel oscillation or the vertical vehicle vibration. Moreover, some resonances in the transfer paths play a significant role in the high-order judder transmission. Although the investigations in this work are limited to three vehicles, the practical significance of high-order hot judder on the driver’s percep-tion is revealed for the first time. With these results, the impact of the measured BTV and BPV of hot judder, e.g. in the brake dynamometer tests, can be assessed. Combining these results, the most effective and efficient way to mitigate the high-order hot judder would be reducing its occurrences in the wheel brakes and diminishing the prominent resonances in the transfer paths

Transfer behaviours and influences of high-order hot judder in passenger cars

Hot judder consists of brake-induced forced vibrations which are characterized by hot spots on the brake discs. It mainly influences the driving comfort as perceived by the driver as vibrations and low-frequency noises. This article concentrates on the transfer behaviours of high-order hot judder and its effects on the driver’s subjective perception. A novel testing method is applied in this investigation, simulating the high-order hot judder by using discs that are artificially modified to generate tenth-order disc thickness variations or tenth-order lateral run-out. A high quality is achieved with respect to identification of the transfer functions from the brake pressure variation and the brake torque variation to the essential driver interface quantities of hot judder. The threshold values of the brake pressure variation and the brake torque variation for perception of the high-order hot judder in a high-frequency range are obtained on the basis of a regression analysis between subjective evluaitons and objective evaluations of the hot-judder-induced vibrations and the selected critical sound pressure level inside a vehicle. Generally, a brake pressure variation of more than 10 bar or a brake torque variation of 100 Nm is required for perception of the high-order judder-induced vibrations, whereas a brake torque variation of 50 Nm can result in annoying noises. According to the transfer functions and the threshold values of the brake pressure variation and the brake torque variation, the drone noise is shown to be the main reason for potential customer complaints arising from high-order hot judder. The practical significance of high-order judder to the driver’s perception is suitably quantified for the first time. Also, with these results, the impacts of high-order hot judder can be assessed from the observed brake pressure variation and the observed brake torque variation, which are mainly measured using dynamometers

6-Methyl-2,4-diphenylquinoline

The molecules of the title compound, C22H17N, are linked by weak interactions, among which the most prominent are C—H...π interactions. The dihedral angles between the phenyl rings and the quinoline ring system are 43.3 (3) and 21.4 (3)°. The title product resulted from a three-component reaction of benzaldehyde, 1-ethynylbenzene and p-toluidine via C—H activation of 1-ethynylbenzene catalyzed by CuI in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

Optimal Scheduling of Cogeneration System with Heat Storage Device Based on Artificial Bee Colony Algorithm

The rigid constraint of using heat in determining electricity for thermal power units is eliminated to improve the absorption capacity of wind power. In this study, heat storage devices and electric boilers are added to the cogeneration system to alleviate the wind curtailment phenomenon. First, the main reasons for wind curtailment are analyzed according to the structural characteristics of the power supply in the northern part of China. Second, a scheduling model of a cogeneration system, including a heat storage device and an electric boiler, is constructed. An improved artificial bee colony algorithm program is also designed and compiled based on MATLAB. Finally, the feasibility of the proposed scheme is verified by simulation examples, and an economic analysis of wind power consumption is performed. Results show that adding electric boilers lessens coal consumption costs and improves economic benefits

A novel JNK from Litopenaeus vannamei involved in white spot syndrome virus infection

National Basic Research Program of China (973 Program) [2012CB114403]; National High Technology Research and Development Program of China (863 Program) [2012AA092205]; China Agriculture Research System-47; National Natural Science Foundation of China [30830084]; Scientific Research Foundation of Third Institute of Oceanography, SOA [2011018]The c-Jun N-terminal kinase (JNK), a member of MAP kinases, is a serine/threonine-specific protein kinase which responds to extracellular stimuli and regulate various cellular activities. It is well documented in innate immune responses and reported to be involved in various viral infections of mammals. In present study, we cloned INK homolog in a crustacean, Litopenaeus vannamei (designated as LvJNK) and studied its role in white spot syndrome virus (WSSV) infection. Sequence analysis displayed that LvJNK shared high similarity with other members of the JNK subfamily, including the conserved TPY motif and serine/threonine protein kinase (S_TKc) domain. Western blot analysis showed that the activation of LvJNK took place in WSSV infection. Lvjnk silencing mediated by specific dsRNA in shrimps could significantly inhibit the proliferation of the virus. Moreover, inhibition of shrimp JNK signaling pathway by specific inhibitor resulted in the reduction of WSSV replication and the delay of WSSV gene transcription. These results indicate for the first time that shrimp JNK is activated in response to WSSV infection and WSSV could benefit from JNK activation. It may facilitate our understanding of the molecular mechanism of virus infection and provided a potential target for preventing the WSSV infection. (c) 2012 Elsevier Ltd. All rights reserved

Molecular cloning and characterization of a cDNA encoding extracellular signal-regulated kinase from Litopenaeus vannamei

Extracellular signal-regulated kinase (ERR) is a serine/threonine-specific kinase, which is activated by downstream signaling molecules of cellular activation, cytokine and chemokine stimulation and various other stimuli. Here we cloned an ERK gene from Litopenaeus vannamei and designated it as lverk. The lverk cDNA contained an open reading frame of 1098 bp encoding 365 amino acids. LVERK had a conserved TEY motif and serine/threonine protein kinase (S_TKc) domain, and close phylogenetic relationship to Penaeus monodon and Marsupenaeus japonicus ERR. Immunofluorescence staining analysis showed that following serum stimulation LVERK was located in cytoplasm and nucleus, but phospho-LVERK was prominently in nucleus, suggesting conserved ERR signaling module occurred in shrimp cells. Then during the white spot syndrome virus (WSSV) infection, LVERK and phospho-LVERK increased at the early stage of infection. Once silencing of lverk in vivo, the replication of WSSV was obviously inhibited. Moreover, treatment of mitogen-activated protein kinase kinase inhibitor in vitro could result in reduction of WSSV proliferation and delay of viral early gene transcription. Our results indicated a role of LVERK involved in WSSV infection. Understanding how WSSV influences ERR signaling pathway to dismantle an effective immune response may lead to insight into pathogenic progression and possible disease control. (C) 2012 Elsevier Ltd. All rights reserved.NSFC/HK-RGC Joint Research Scheme [N_HKUST609/09]; NSFC [20931160426

Optimal Scheduling of Cogeneration System with Heat Storage Device Based on Artificial Bee Colony Algorithm

The rigid constraint of using heat in determining electricity for thermal power units is eliminated to improve the absorption capacity of wind power. In this study, heat storage devices and electric boilers are added to the cogeneration system to alleviate the wind curtailment phenomenon. First, the main reasons for wind curtailment are analyzed according to the structural characteristics of the power supply in the northern part of China. Second, a scheduling model of a cogeneration system, including a heat storage device and an electric boiler, is constructed. An improved artificial bee colony algorithm program is also designed and compiled based on MATLAB. Finally, the feasibility of the proposed scheme is verified by simulation examples, and an economic analysis of wind power consumption is performed. Results show that adding electric boilers lessens coal consumption costs and improves economic benefits