With the development of intelligent manufacturing and automation, the precision and complexity of mechanical equipment are increasing, which leads to a higher requirement for fault diagnosis. Fault ...diagnosis has gradually transformed from traditional diagnosis algorithm to deep feature mining and expression of highly nonlinear, complex and multidimensional systems. At present, the mechanical fault signals of various equipment are mostly time series. In addition, recurrent neural network (RNN) has strong nonlinear feature learning and processing ability of time sequence information, which has achieved promising results in mechanical fault diagnosis and big data processing. Therefore, this study reviews state-of-the-art RNN method in mechanical fault diagnosis and introduces applications from two aspects: RNN and the combined neural networks which include RNN. Then, this paper discusses the challenges and future development of RNN based fault diagnosis.
During the bioconversion of xylose to ethanol,
Pichia stipitis
cells are often inhibited by substances generated in the lignocellulosic hydrolysate. However, the response mechanism of
P. stipitis
to ...inhibitors has not been completely understood till date. With this aim, integrated transcriptomic and metabolomic analyses were performed on
P. stipitis
to investigate the interactive effects of three representative inhibitors vanillin, 5-hydroxymethylfurfural (5-HMF), and acetic acid present in lignocellulosic hydrolysates. The genes involved in carbohydrate metabolism were observed to significantly down-regulated in the presence of the three combined inhibitors in both lag and middle exponential phases. In addition, inhibitor addition induced amino acid metabolism (e.g., glutamine and asparagine syntheses), since the yeast cells required more amino acids in stressful conditions. The metabolomic analysis yielded similar results, particularly those related with the analysis of metabolic biomarkers including fatty acids, amino acids, and sugars. 70 intracellular metabolites were detected by gas chromatography coupled with mass spectrometry (GC–MS), and samples from different phases were clearly separated by principal component analysis (PCA). The large amount of specific responsive genes and metabolites highlighted the complex regulatory mechanisms involved in the fermentation process in the presence of the three combined inhibitors.
We aimed to explore the correlations of high molecular weight adiponectin (HMW-ADP), tumor necrosis factor-alpha (TNF-α) and vascular endothelial growth factors (VEGFs) with the occurrence of colonic ...polyps in the prediabetic population. Two hundred patients with prediabetes were enrolled, and their clinical data were retrospectively analyzed. They were divided into group A (75 patients with colonic polyps) and group B (125 patients without colonic polyps). Eighty patients with normal glucose tolerance in the same period were divided into group C (32 patients with normal glucose tolerance and colonic polyps) and group D (48 patients with normal glucose tolerance but no colonic polyps). The correlations of serum HMW-ADP, TNF-α and VEGF levels with plasma glucose and insulin levels were explored by Pearson’s analysis. The factors influencing the occurrence of colonic polyps were determined by logistic regression analysis. Serum HMW-ADP was negatively correlated with TNF-α, VEGFs, FPG, 2hPG, FI and HOMA-IR (
r
<0, P<0.05), whereas serum TNF-α and VEGFs were positively correlated with FPG, 2hPG, FI and HOMA-IR (
r
>0, P<0.05). Age, body mass index, waist-to-hip ratio, history of smoking, history of drinking, family history of colon cancer, TNF-α and VEGF were independent risk factors odds ratio (OR)>1, P<0.05, and HMW-ADP was a protective factor (OR<1, P<0.05). The areas under the curves of serum HMW-ADP, TNF-α, VEGFs and their combination for predicting the occurrence of colonic polyps were 0.899, 0.787, 0.908 and 0.922, respectively. The combination of HMW-ADP, TNF-α and VEGFs can effectively predict the occurrence of colonic polyps in prediabetic patients.
The aim of this study was to compare the biomechanical performance of 6 pedicle screw internal fixation strategies for the treatment of burst fractures of the thoracolumbar spine using finite element ...(FE) analysis.
A finite element model of the T11-L3 thoracolumbar segment was established to simulate L1 vertebral burst fractures, and 6 models were conducted under multidirectional loading conditions: P2-D2, P1-D1, P2-D1,P1-D, P1-BF-D1, and P1-UF-D1. The range of motion (ROM) in the T12-L2 region and the von Mises stresses of pedicle screws and rods under the 6 internal fixation models were mainly analyzed.
The maximum ROM and von Mises stress were obtained under flexion motion in all models. The P1-BF-D1 model had the least ROM and screw stress. However, when the injured vertebra was not nailed bilaterally, the P1-UF-D1 model had the smallest ROM; the maximum von Mises stress on the screw and rod was remarkably higher than that recorded in the other models. Moreover, the P2-D1 model had a ROM similar to that of the P1-D2 model, but with lower screw stress. The 2 models outperformed the P1-D1 model in all 6 conditions. The P2-D2 model had a similar ROM with the P2-D1 model; nevertheless, the maximum von Mises stress was not substantially reduced.
The P1-BF-D1 model exhibited better stability and less von Mises stress on the pedicle screws and rods, thereby reducing the risk of screw loosening and fracture. The P2-D1 internal fixation approach is recommended when the fractured vertebrae are not nailed bilaterally.
This paper presents an antilock braking system/direct yaw-moment control (ABS/DYC) coordinated control scheme in order to shorten the braking distance while ensuring the vehicle stability during ...emergency braking under complex driving conditions. Particularly, the braking actuator failure and driving on low-<inline-formula> <tex-math notation="LaTeX">\mu </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\mu </tex-math></inline-formula>-split roads are considered. The proposed control scheme is composed of three cascaded controllers. The first-level controller is used to derive and trace the desired yaw rate for DYC control based on the driver's intent, exert conventional ABS control to maximize the braking force without considering braking actuator fault occurrence, and synthesize constraint conditions such as braking actuator failure and so forth. The second-level controller is used to determine on which side to fully capitalize for the maximum tire/road adhesion utilization. The third-level controller is leveraged to realize optimal torque allocation to each actuation motor with the purpose of minimizing the tire load. The effectiveness of the proposed ABS/DYC coordinated control scheme is verified through both simulation and hardware-in-loop experimentation.
The spatial political logic of the construction of Chinese metropolitan areas (CMAs) is unique and complex, involving the interaction of power, spatial production, and the construction of political ...rationality between multiple scales. Taking the representative Nanjing metropolitan area as an example, we use the “material–organizational–discursive” analytical framework of politics of scale theory to analyze the construction logic of CMAs. This study finds the following: (1) In general, the CMA is a high-quality spatial construction resulting from multi-city negotiation, inter-provincial collaboration, and central–territory linkage, and has generally undergone a process of increasing the power of subjects, nested power relations, frequent scale interactions, and complex interest games; among them, planning is not only a scale tool for competing for power, but also an important representation of the results of multiple power games. (2) In terms of the construction of material space, both the delineation of boundaries and the cross-border connection of infrastructure represent rational thinking and stand as two-way choices of the two power subjects in the MA based on the maintenance and expansion of their own spatial development rights. (3) In terms of organizational space construction, CMAs mainly adopt flexible means, with bilateral and multilateral cooperation at the horizontal level, while there is a certain power inequality at the vertical level. (4) In the construction of discursive space, CMAs have experienced increasing construction significance, escalating scale subjects, and overlapping discourse narratives, and the contrast of power relations has also changed. The contribution of this paper is an expansion of the analytical framework of politics of scale based on the division of spatial dimensions, which provides a new perspective for understanding the construction of CMAs, and also helps us to picture Chinese city–regionalism.
•An integrated process was to produce ethanol, vanillin, and xylooligosaccharides.•NaOH pretreatment was to obtain the solid residue and the liquid fraction.•The residue after enzymatic hydrolysis ...was further fermented to produce ethanol.•The liquid was firstly hydrolyzed with xylanase to produce xylooligosaccharides.•The liquid after xylanase hydrolysis was further oxidized to produce vanillin.
This study aims to present an integrated process that can be used to produce ethanol, vanillin, and xylooligosaccharides from Camellia oleifera shell. After the shell was pretreated with NaOH, two fractions were obtained: solid and liquid fractions. The solid fraction was hydrolyzed with cellulase and then fermented with Pichia stipitis to produce ethanol. The liquid fraction was subjected to oxidation to prepare vanillin or hydrolysis with xylanase to prepare xylooligosaccharides. The optimal pretreatment conditions of an orthogonal test were as follows: 12% NaOH concentration; 120°C; 150min; and liquid–solid ratio of 10.0. After pretreatment, the solid fraction containing cellulose and a small part of xylan at 10% substance concentration via enzymatic hydrolysis and glucose–xylose cofermentation could obtain 17.35g/L of ethanol, 80.90% of the theoretical yield. The liquid fraction was initially hydrolyzed with xylanase to produce 1758.63mg/L of xylooligosaccharides (DP2–6) and then oxidized to produce 322.07mg/L of vanillin.
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