Genetic Detection for Large-Scale Multiuser MIMO Systems in Presence of Non-Gaussian Noise

Tianyang Zhang,Rong Ran,Hayoung Oh 한국통신학회 2019 한국통신학회 학술대회논문집 Vol.2019 No.1

In many wireless systems, the ambient noise is known through experimental measurements to be decidedly non-Gaussian due to impulsive phenomena. Many conventional multiuser detectors may suffer a considerable performance loss in the presence of such impulsive ambient noise. In this paper, we study a large-scale multiuser multipleinput multiple-output (MIMO) system in presence of non-Gaussian noise. For the system, we present a genetic algorithm (GA) for a large-dimensional signal detecting as it performs multi-direction search by manipulating and maintaining a population of potential solutions, and thus can be more robust than other conventional detectors, especially with the presence of non-Gaussian noises. Meanwhile, GA can be less complicated than other conventional detectors since it doesn’t require any complicated computations (e.g., matrix inverse and derivation). Simulation results show that the GA detector offers performance gain over the linear Minimum Mean Square Error (MMSE) detector in presence of non-Gaussian noise as well as Gaussian noise.

Industrial Solid Waste-Based Layered Double Hydroxide Composite with Enhanced Adsorption Affinity to Congo Red, Acid Red, and Reactive Red

Zhang Siqian,Lee Jaewon,Li Bin,Zhang Tianyang,백성현,심상은 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.3

The synthesis of hierarchically porous materials from industrial solid waste as catalysts or adsorbents has attracted much attention in environmental pollution control. The present work highlights the synthesis of a series of MgFeAl layered double hydroxide (LDH) with diff erent ratios of Mg/(Fe + Al) from red mud and ferronickel slag under diff erent pH to decolorize three red dye solutions, namely, Congo red (CR), acid red (AR), and reactive red (RR). The maximum adsorption capacity (386.1 mg.g −1 ) for CR was obtained by the MgFeAl-LDH sample with Mg/(Fe + Al) mole ratio of 2 synthesized under pH 10. The optimized synthesis parameters led to a high surface area and large pore volume of MgFeAl-LDH, thereby enhancing the mass transfer of adsorbate to the active sites of the adsorbent. Further, the MgFeAl-LDH sample was also effi cient in removing AR (120.9 mg.g −1 ) and RR (114 mg.g −1 ). Moreover, the adsorption kinetics and isotherms of MgFeAl-LDH fi tted well with the pseudo-second-order and Langmuir models, respectively. The MgFeAl-LDH system developed a valuable approach to utilize industrial waste for dye removal.

Comparison of Dynamic Characteristics between Virtual Synchronous Machines Adopting Different Active Power Droop Controls

Yuan, Chang,Liu, Chang,Zhang, Xueyin,Zhao, Tianyang,Xiao, Xiangning,Tang, Niang The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

In modern power systems, high penetration of distributed generators (DGs) results in high stress on system stability. Apart from the intermittent nature of DGs, most DGs do not contribute inertia or damping to systems. As a result, a new control method named virtual synchronous machine (VSM) was proposed, which brought new characteristics to inverters such as synchronous machines (SMs). In addition, different active power droop controls for VSMs are being proposed in literatures. However, they are quite different in terms of their dynamic characteristics despite of the similar control laws. In this paper, mathematical models of a VSM adopting different active power droop controls are built and analyzed. The dynamic performance of the VSM output active power and virtual rotor angular frequency are presented for different models. The influences of the damping factor and droop coefficient on the VSM dynamic behaviors are also investigated in detail. Finally, the theoretical analysis is verified by simulations and experimental results.

Comparison of Dynamic Characteristics between Virtual Synchronous Machines Adopting Different Active Power Droop Controls

Chang Yuan,Chang Liu,Xueyin Zhang,Tianyang Zhao,Xiangning Xiao,Niang Tang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

In modern power systems, high penetration of distributed generators (DGs) results in high stress on system stability. Apart from the intermittent nature of DGs, most DGs do not contribute inertia or damping to systems. As a result, a new control method named virtual synchronous machine (VSM) was proposed, which brought new characteristics to inverters such as synchronous machines (SMs). In addition, different active power droop controls for VSMs are being proposed in literatures. However, they are quite different in terms of their dynamic characteristics despite of the similar control laws. In this paper, mathematical models of a VSM adopting different active power droop controls are built and analyzed. The dynamic performance of the VSM output active power and virtual rotor angular frequency are presented for different models. The influences of the damping factor and droop coefficient on the VSM dynamic behaviors are also investigated in detail. Finally, the theoretical analysis is verified by simulations and experimental results.

Study on micro-grinding mechanism and surface and subsurface quality of 20 vol% SiCp/Al composites

Xunyu Yin,Qi Gao,Quanzhao Wang,Ye Chen,Tianyang Cui,Ke Zhang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

A finite element model of single abrasive grinding was established to analyze the material removal during the grinding process and analyze the surface and subsurface defects of the material after grinding. Using the orthogonal test method to machine the surface of the workpiece with a grinding rod of 2 mm grinding head diameter, and to investigate the influence degree of the machining parameters on the roughness. It was concluded that the grinding depth has the most significant effect on surface roughness, followed by the spindle speed and the feed speed, and the minimum roughness of the ground surface obtained was 0.066 μm. The rough surface was simulated by the digital filtering method based on fast Fourier transform (FFT), and the morphological characteristics of the rough surface at Ra = 0.116 μm were described, and the simulated surface was consistent with the detected surface. The laser scanning confocal microscope (LSCM) and scanning electron microscope (SEM) were used for inspection, and the analysis showed that the main removal forms of the enhanced particles were broken, fractured, and pulled out. The surface defects were cracks, pits, and burrs, and the subsurface damages were voids, cracks, and pits.

Population dynamics of Frankliniella occidentalis Pergrande and its predator Orius similis Zheng on common crops and surrounding plants

Hu Changxiong,Li Yiru,Chen Guohua,Duan Pan,Wu Daohui,Liu Qing,Yin Honghui,Xu Tianyang,Zhang Xiaoming 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

Frankliniella occidentalis Pergrande is important invasive pests in China, causing damage to agricultural pro duction, and Orius similis Zheng is the dominant predator species of F. occidentalis. A two-year survey was conducted to determine the population density of F. occidentalis and O. similis, on chili (Capsicum annuum L.) and maize (Zea mays L.) crops and surrounding weed species, which included white clover (Trifolium repens L.), St. John’s wort (Hypericum beanii N. Robson), alfalfa (Medicago sativa L.) and beggarticks (Bidens pilosa L.) in Kunming, southern China. The activity of F. occidentalis on these 6 host plant species was determined using the quartile method. F. occidentalis mainly damaged plants during their flowering stage. The main activity period of F. occidentalis occurred earlier on H. beanii and T. repens than on C. annuum. The peak activity of F. occidentalis occurred in the middle of May (on T. repens). During the whole activity period, the highest thrips densities were recorded on H. beanii among all of the sampled host plant species, followed by C. annuum. The lowest density was recorded on B. pilosa. Dynamics of immature F. occidentalis were more irregular than that of adults. The highest density of O. similis was recorded on Z. mays. It was 2.27–26.43-fold (2017) and 2.01–19.09-fold (2018) higher than that on other host plant species. This study showed that F. occidentalis could migrate between C. annuum and surrounding weeds. The weeds were the main source of thrips on C. annuum. The results indicated that Z. mays can be planted around C. annuum fields as a potential banker plant, to attract O. similis to control F. occidentalis on C. annuum, T. repens and B. pilosa. The flowering period of plants and surrounding plant species has a great effect to the population activities of F. occidentalis and predator O. similis on crops.

Impact of Latrogenic Biliary Injury during Laparoscopic Cholecystectomy on Surgeon’s Mental Distress A Nationwide Survey from China

( Tian Yang ),( Hai-su Dai ),( Lei Liang ),( Cheng-cheng Zhang ),( Zhang-jun Cheng ),( Yong-hai Peng ),( Yao-ming Zhang ),( Zhi-yu Chen ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: Iatrogenic biliary injury (IBI) following laparoscopic cholecystectomy (LC) is the most common and recognized iatrogenic complications. Little is known whether LC-IBI would lead to surgeon’s mental distress. This study reports the incidence of surgeon’s mental distress who have caused LC-IBI and risk factors of surgeon’s severe mental distress (SMD). Methods: A cross-sectional survey in the form of electronic questionnaire was conducted among Chinese general surgeons who have caused LC-IBI. The six collected clinical features relating to mental distress included: 1) feeling burnout, anxiety, or depression, 2) avoiding performing LC, 3) having physical reactions when recalling the incidence, 4) having the urge to quit surgery, 5) taking psychiatric medications, and 6) seeking professional psychological counseling. Univariable and multivariable analyses were performed to identify risk factors of SMD, which was defined as meeting ≥3 of the above-mentioned clinical features. Results: Among 1,466 surveyed surgeons, 1,236(84.3%) experienced mental distress following LC-IBI, and nearly half (49.7%, 614/1236) had SMD. Multivariable analyses demonstrated that surgeons from non-university affiliated hospitals (OR:1.873), patients who required multiple repair operations (OR:4.075), patients who required hepaticojejunostomy/partial hepatectomy (OR:1.859), existing lawsuit litigation (OR:10.491), existing violent doctor-patient conflicts (OR:4.995), needing surgeons’ personal compensation (OR:2.531), and additional administrative punishment by hospitals (OR:2.324) were independent risk factors of surgeon’s SMD. Conclusions: Four out of five surgeons experienced mental distress following LC-IBI, and nearly half had SMD. Several independent risk factors of SMD were identified, which could help to make strategies to improve mental well-being of these surgeons.