Studies on the Temperature Control System of the Geothermal-Source Heat Pump under Different Modes

Hu Tao,Su Huashan,Hong Feng,Xiao Renzheng,Zhu Jialing 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.3

Geothermal-source heat pump technology can increase the production efficiency and reduce the energy consumption. However, the application performance of the control system for the geothermal-source heat pump is always poor; such as a larger system operation energy consumption, low efficiency, poor stability and time effectiveness. In order to solve this issue, two advanced control strategies based on the research object of the geothermal-source heat pump temperature control system with different modes are developed: one is a feedforward-feedback control based on the variable speed integral PID control algorithm (“FFC-VSIPC”), the other is a feedforward-feedback control based on the fuzzy control algorithm (“FFC-FC”). The simulation and experimental studies of the effects of temperature control system in a geothermal-source heat pump by different models are carried out. The results shows that: (1) The overshoot of FFC-VSIPC is slightly larger than the FFC-FC when the set value is abruptly changed, but the adjustment time of FFC-VSIPC is shorter and there is no static error after the stabilization; (2) Changing the rate of flow interference suddenly, both FFC-VSIPC and FFC-FC can effectively eliminate the effects of interference with adding a feedforward control, also the adjustment time of FFC-VSIPC is greatly shortened than FFC-FC, but the stability of the adjustment is worse; (3) When the frequency amplification factor is suddenly changed, FFC-FC shows a non-stable control state of divergence gradually, FFC-VSIPC shows good robustness. The further comparisons between simulations and experiments reveal that FFC-VSIPC is better than FFC-FC in terms of the energy regulation and controlling of the geothermal source heat pump. Therefore, FFC-VSIPC is an advanced control strategy, which is worthy of research and application promotion.

Initial Report on the Oriented-precipitation of T1-Phase in Creep-Aged Al-Cu-Li Single Crystal

Wei Hu,Jiqiang Chen,Shuang Han,Jinjun Xu,Jiale Miao,Ting Xing,Renguo Guan 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5

In this work, the precipitation behavior of the T1-phase on each {111}Al habit plane was characterized by transmissionelectron microscopy (TEM), which was observed along two < 110 > Al zone axes in an Al-Cu-Li single crystal during creepaging. The results indicate that the oriented-precipitation of T1-phase in the Al-Cu-Li single crystal was originally determinedduring creep aging. The number densities of the T1-phase on the habit planes of (111)Al and (1−11)Al is noticeablyhigher than those of the T1-phase on the habit planes of (−111)Al and (11−1)Al in the same Al-Cu-Li single crystal when theexternal stress is loaded along the direction close to [111]Al orientation. It implies that the T1-phase tends to preferentiallyprecipitate on the habit planes that are perpendicular to the loading direction during creep aging. This work provides theinitial experimental evidence of the oriented-precipitation of the T1-phase in Al-Cu-Li alloy, and proposes the possibilityof regulating the precipitation distribution of the T1-phase.

Madecassic acid protects human periodontal ligament fibroblasts against hydrogen peroxide-induced cell damage by maintaining mitochondrial membrane potential

Jin Yuqin,Li Jialing,Ding Liang,Zhao Qing,Song Yuxian,Li Guifeng,Ji Jun,Ni Yanhong,Hu Qingang 대한독성 유전단백체 학회 2022 Molecular & cellular toxicology Vol.18 No.1

Background Oxidative stress is involved in the pathogenesis of various inflammatory diseases, such as periodontitis. When periodontitis occurs, reactive oxygen species (ROS) are overproduced and cannot be balanced by the antioxidant defense system, resulting in tissue damage. Madecassic acid (MA), an abundant triterpenoid in Centella asiatica (L.) Urban, has been used as a wound healing, antiinflammatory, and anticancer agent. Moreover, recent studies have shown that MA has an antioxidative effect, but the underlying mechanism remains unclear. Objective Here, we established an effective oxidative stress model induced by hydrogen peroxide (H 2 O 2 ) in human periodontal ligament fi broblasts (hPDLFs) to investigate the antioxidant and protective effects of MA against cell damage and its underlying mechanism of action. Results Pretreatment with MA inhibited cell apoptosis and promoted cell invasion and migration against oxidative injury induced by H 2 O 2 . In addition, MA was able to maintain mitochondrial membrane potential (ΔΨm) under oxidative stress. Notably, we found that MA restored redox balance by reducing intracellular ROS production. Furthermore, we investigated apoptosis-related proteins and found that the levels of anti-apoptosis markers Bcl-xL and Bcl-2 were remarkably upregulated, whereas that of the pro-apoptotic marker Bax was strikingly downregulated. Conclusions Collectively, these findings suggest that MA inhibits H 2 O 2 -induced oxidative stress and apoptosis of hPDLFs by reducing intracellular ROS production to maintain ΔΨm stability.

A fault diagnosis method using Interval coded deep belief network

Jiahui Tang,Jimei Wu,Bingbing Hu,Chang Guo,Jialing Zhang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5

The rolling bearing, though a widely used component in rotating machinery, is also failure-prone. There are some difficulties in extracting valuable fault features from the vibration signal generated by the rolling bearing operation. Based on the interval coded deep belief network, an improved method for fault diagnosis is introduced to deal with the existing problems. Interval code is an encoding method to characterize fault features by using bearing vibration amplitude distribution. This method can also reduce the complexity of the original data and integrate input dimension. The deep belief network can remove the dependence from manual feature extraction and quickly extract the fault features from coding results. This proposed method is employed in the fault diagnosis experiments of rolling bearing to evaluate the performance. From the obtained experiment results, it can be concluded that the interval coded deep belief network boosts performance, which can eliminate the limitation of the input data dimension in the traditional deep learning model.

Feasibility of Two-Screw Anterior Fixation for Odontoid Fractures in a Chinese Population: A Morphometric Study Based on Computed Tomography

Yixiang Ai,Dereje Gobena Alemayehu,Genwen Mao,Yaping Liang,Ran Cao,Jiale Hu,Yimin Yang,Zhiwei Ren 대한정형외과학회 2023 Clinics in Orthopedic Surgery Vol.15 No.6

Background: To evaluate the feasibility of treating odontoid fractures in the Chinese population with two cortical screws based on computed tomography (CT) scans and describe a new measurement strategy to guide screw insertion in treating these fractures. Methods: A retrospective review of cervical computed tomographic scans of 128 patients (aged 18–76 years; men, 55 [43.0%]) was performed. The minimum external transverse diameter (METD), minimum external anteroposterior diameter (MEAD), maximum screw length (MSL), and screw projection back angle (SPBA) of the odontoid process were measured on coronal and sagittal CT images. Results: The mean values of METD and MEAD were 10.0 ± 1.1 mm and 12.0 ± 1.0 mm, respectively, in men and 9.2 ± 1.0 mm and 11.0 ± 1.0 mm, respectively, in women. Both measurements were significantly higher in men (p < 0.001). In total, 87 individuals (68%) had METD > 9.0 mm that could accommodate two 3.5-mm cortical screws. The mean MSL value and SPBA range were 34.4 ± 2.9 mm and 13.5°–24.2°, respectively, with no statistically significant difference between men and women. Conclusions: The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fractures in 87 patients (68%) in our study, and there was a statistically significant difference between men and women.