The growing demand for prolonged fatigue life of automotive parts and components requires elaboration of their motion in Cartesian space having six degrees of freedom (DOF). Recently, the canonical Steward platform, consisting of six displacement sensors mounted on two parallel platforms, was introduced to comply with this request. In order to apply this pose sensor to automotive applications, the following two important matters are investigated in this study. First, update Jacobian is proposed as a faster and more stable numerical method to solve the forward kinematic problem without any iteration process. Second, the attachment position and initial configuration of the Stewart platform must be adjustable to avoid the interference with other components due to space constraints under the hood of automotive vehicle. In this case, however, the Jacobian matrix which converts six displacement components into a six DOF pose vector is prone to be ill-conditioned so that the converting accuracy becomes worse. The L1-norm of each row in the Jacobian matrix quantifies how much the error would be provoked according to the given kinematic geometry. Hence, it can be used here as a reliable error indicator. Furthermore, several numerical examples are discussed to demonstrate what to consider when designing a six DOF pose sensor for automotive applications. 相似文献
Journal of Mechanical Science and Technology - This paper presents the design and modeling of the UNI-Copter, a portable spherical unmanned aerial vehicle (UAV) that is powered by a single rotor.... 相似文献
A process for methanol production from 100 MM scfd of stranded gas and CO2 is proposed and simulated using a commercial process simulator, PRO/II v.9.1, for a FPSO (floating production, storage, off-loading) system. The process consists of Steam-CO2 Reforming (SCR), methanol synthesis, a Reverse Water-Gas Shift (RWGS) reaction and ancillaries with recycle streams to SCR and RWGS. All reactors were simulated using the Gibbs reactor model. Also, the Plug Flow Reactor (PFR) model with reaction rate equations was used for the methanol reactor and the result was compared to the Gibbs reactor model. To maximize the use of the carbon source in stranded gas and CO2 while avoiding an undesirable increase in process size, the optimum recycle ratios were calculated with a satisfying constraint, a steam-to-carbon ratio ≥ 1 in the SCR. In the proposed Methanol-FPSO process the RWGS reactor can maximize CO2 utilization and case studies were performed to analyze the influence of RWGS. 相似文献
The palladium‐catalyzed, one‐pot arylative cyclization of 3‐(γ,δ‐disubstituted)allylidene‐2‐oxindoles afforded spirodihydronaphthalene‐2‐oxindole frameworks via an oxidative Heck arylation (Fujiwara–Moritani reaction), an allylic palladium migration, and an aryl C H bond functionalization/arylation cascade of reactions. This is a first example of the palladium‐catalyzed oxidative arylation and an aryl C H bond functionalization/arylation cascade reaction which involves an electrophilic arylative quenching of a π‐allylpalladium intermediate and a regio‐controlled aryl C H bond activation assisted by a weak palladium‐arene interaction.
We compared novel size‐selective separators, namely the textile fabrics of polyphenylene sulfide (PPS) and sulfonated polyphenylene sulfide (S‐PPS), and the nonwoven fabrics of polypropylene80 (PP 80) and PP 100, with commonly used ion exchange separators (Nafion 117 and cation exchange membane‐7000; CMI‐7000) in terms of power generation, oxygen diffusion, and biofilm formation in a single chamber microbial fuel cell. Size‐selective separators exhibited more power generation than ion selective separators. MFC operation with size‐selective separators generated power output ranging 0.407 to 0.591 V (1000 Ω), whereas with Nafion it was 0.272 V. In polarization analysis, S‐PPS resulted in the highest power density of 190 mW/m2, whereas it was 24 mW/m2 with Nafion‐117. Size selective separators showed similar or higher proton conductivity than Nafion 117. Oxygen mass transfer coefficients of size‐selective separators (KO = 3.7 ∼ 7.5 × 10−5) were lower or similar to Nafion (KO = 7.5 × 10−5). Fourier‐transform infrared spectroscopy and scanning electron microscopy analysis revealed that all separators (PP80, S‐PPS, and Nafion) contained proteins or carbon chain compounds after 300‐day operation, and however, Nafion 117 seems to be more susceptible to biofouling than the other separators. 相似文献
Introduction: A recent study showed that early renal tubular injury is ameliorated in Nod-like receptor pyrin domain-containing protein 3 (NLRP3) KO mice with rhabdomyolysis-induced acute kidney injury (RIAKI). However, the precise mechanism has not been determined. Therefore, we investigated the role of NLRP3 in renal tubular cells in RIAKI. Methods: Glycerol-mediated RIAKI was induced in NLRP3 KO and wild-type (WT) mice. The mice were euthanized 24 h after glycerol injection, and both kidneys and plasma were collected. HKC-8 cells were treated with ferrous myoglobin to mimic a rhabdomyolytic environment. Results: Glycerol injection led to increase serum creatinine, aspartate aminotransferase (AST), and renal kidney injury molecule-1 (KIM-1) level; renal tubular necrosis; and apoptosis. Renal injury was attenuated in NLRP3 KO mice, while muscle damage and renal neutrophil recruitment did not differ between NLRP3 KO mice and WT mice. Following glycerin injection, increases in cleaved caspase-3, poly (ADP-ribose) polymerase (PARP), and a decrease in the glutathione peroxidase 4 (GPX-4) level were observed in the kidneys of mice with RIAKI, and these changes were alleviated in the kidneys of NLRP3 KO mice. NLRP3 was upregulated, and cell viability was suppressed in HKC-8 cells treated with ferrous myoglobin. Myoglobin-induced apoptosis and lipid peroxidation were significantly decreased in siNLRP3-treated HKC-8 cells compared to ferrous myoglobin-treated HKC-8 cells. Myoglobin reduced the mitochondrial membrane potential and increased mitochondrial fission and reactive oxygen species (ROS) and lipid peroxidation levels, which were restored to normal levels in NLRP3-depleted HKC-8 cells. Conclusions: NLRP3 depletion ameliorated renal tubular injury in a murine glycerol-induced acute kidney injury (AKI) model. A lack of NLRP3 improved tubular cell viability via attenuation of myoglobin-induced mitochondrial injury and lipid peroxidation, which might be the critical factor in protecting the kidney. 相似文献
It has been proposed that Mg2+ and Fe2+ are very similar in interacting with ribozymes and some protein-based enzymes, but their activities with DNAzymes have yet to be studied. Here, the activity of Fe2+ as cofactor for a few RNA-cleaving DNAzymes is investigated. 17E is a well-studied DNAzyme that is active in the presence of many different divalent metal ions; it is highly active with Fe2+ with an apparent Kd of 29.7±2.3 μm and a kobs of 1.12±0.11 min−1 in the presence of 1 mm Fe2+ at pH 7.5. Fe2+ has 21-fold higher activity than Mg2+. Six different DNAzymes are then tested, and only the DNAzymes active with Mg2+ (17E, 8–17, and E5) are active with Fe2+. Fe2+ has 25 and one- to twofold higher activity than Mg2+ for the 8–17 and E5 DNAzymes, respectively. In pH>7 buffer and in presence of air, 1 mm Fe2+ results in a nonspecific degradation of the DNA strand due to reactive oxygen species (ROS). Cleavage reactions in anoxic environment and antioxidant ascorbate can be used to overcome the effect of oxidation. The findings provide insights for potential DNAzyme catalysis in the early Earth, and they further support the similarity between Mg2+ and Fe2+ in enzyme catalysis. 相似文献
The effect of pH on the initiation of germination and on the inactivation of Bacillus cereus (KCTC 1012) spores during high hydrostatic pressure processing (HPP) with pressures of 0.1 to 600 MPa at different temperatures was investigated. Two different high-pressure treatments were adopted to evaluate the effect of pH on the inactivation of B. cereus on sporulation medium and in suspension medium. Inactivation of B. cereus spores with HPP treatment was affected more by sporulation medium pH than by suspension medium pH. B. cereus spores obtained through sporulation at pH 6.0 showed more resistance to inactivation by HPP at 20, 40, and 60 degrees C than did those obtained through sporulation at pHs of 7.0 and 8.0. Constituents of B. cereus spores obtained through sporulation at pH 6.0 may undergo electrochemical charge changes comparable to those for spores obtained through sporulation at pH 7.0. The initiation of B. cereus spore germination was more sensitive to pressure around 300 MPa at 20 degrees C. Increasing processing temperatures during HPP enhanced the effect of sporulation medium pH (i.e., environmental pH) on the inactivation of B. cereus spores. 相似文献