Implementation of DSTFCs in MIMO MB-IR-UWB System

Zheng Dou,Zijing Jin,Yun Lin,Zhiqiang Wu,Zhiping Zhang 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.3

This paper implements differential space-time-frequency codes (DSTFCS) to multiple-input multiple-output (MIMO), multi-band impulse radio ultra-wideband (MB-IR-UWB) system. Four scenarios of the system operating mode have been put forward and combination of DSTFCs and the system has been studied in this paper. Through simulation, a comparison of BER performance among different scenarios and channel statements is analyzed. In addition, considered inter-symbol interference (ISI), the simulation on system with ISI and without ISI is given. Finally the conclusion that scenario 3 is more suitable to the proposed MIMO MB-IR-UWB system for it being less sensitive to ISI has been drawn.

Detection Method of Weak Low-Frequency Electromagnetic Signal Based on Multi-layer Autocorrelation

Zheng Dou,Yu Tao,Yun Lin,Zhiqiang Wu,Dong Li,Zhiping Zhang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.4

Low frequency electromagnetic signals play an important role in the detection of underground electrical structure. After propagation of long distance, signal will be attenuated to a certain extent and probably buried in noise, make it difficult to extract. In this paper, the method of multi-layer autocorrelation will be used to detect and extract the weak low frequency electromagnetic signal, and its performance will be compared with the narrow-band filter and the method of synchronous accumulation. Simulation results show that the correlation coefficient of signal obtained by multi-layer autocorrelation and source signal can achieve more than 0.8 when SNR is -18dB. However, the value of narrow-band filter and synchronous accumulation is lower than that mentioned above when SNR is only -14dB. Experimental verifies that multi-layer autocorrelation method can suppress noise more effectively and detect weak signals more accurately.

An Optimized MPC Method for Restraining the Midpoint Voltage Fluctuation of 3-Level T-Type Grid-Connected Inverter

Dou Zhifeng,Wang Nan,Chen Zhinan,Zheng Anping,Lu Falong,Lv Zhongbin 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

Conventional Finite Control Set Model Predictive Control (FCS-MPC) suffers from large neutral point voltage fluctuation, cumbersome calculation process, as well as high current Total Harmonic Distortions for 3-level T-type grid-tied inverter. An improved FCS-MPC method is proposed in this paper by directly calculating the switch state’s cost function. This method uses the 3-phase switching state Sx to represent the load current i, the DC side neutral point voltage offset ΔUc, the load current prediction value i(k + 1), and establishes a real-time cost function g through 27 switching vectors. In the loop calculation, the switching vector is selected by minimizing the absolute value of the cost function g, and the output switching state is represented by the switching vector. Thus, the inverter can be switched ON or OFF depending on the stat of the next moment. The FCS-MPC of a 3-level T-type grid-tied inverter is also established by simulation, and the effectiveness of the proposed method is verified by experimental results.

Drug-loaded microbubble delivery system to enhance PD-L1 blockade immunotherapy with remodeling immune microenvironment

Zheng Jun,Huang Ju,Zhang Liang,Wang Mengna,Xu Lihong,Dou Xiaoyun,Leng Xiaojing,Fang Mingxiao,Sun Yang,Wang Zhigang 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Although programmed cell death protein 1 (PD-1)/ programmed cell death-ligand protein 1 (PD-L1) checkpoint blockade immunotherapy demonstrates great promise in cancer treatment, poor infiltration of T cells resulted from tumor immunosuppressive microenvironment (TIME) and insufficient accumulation of anti-PD-L1 (αPD-L1) in tumor sites diminish the immune response. Herein, we reported a drug-loaded microbubble delivery system to overcome these obstacles and enhance PD-L1 blockade immunotherapy.Docetaxel (DTX) and imiquimod (R837)-loaded microbubbles (RD@MBs) were synthesized via a typical rotary evaporation method combined with mechanical oscillation. The targeted release of drugs was achieved by using the directional "bursting" capability of ultrasound-targeted microbubble destruction (UTMD) technology. The antitumor immune response by RD@MBs combining αPD-L1 were evaluated on 4T1 and CT26 tumor models.The dying tumor cells induced by DTX release tumor-associated antigens (TAAs), together with R837, promoted the activation, proliferation and recruitment of T cells. Besides, UTMD technology and DTX enhanced the accumulation of αPD-L1 in tumor sites. Moreover, RD@MBs remolded TIME, including the polarization of M2-phenotype tumor-associated macrophages (TAMs) to M1-phenotype, and reduction of myeloid-derived suppressor cells (MDSCs). The RD@MBs + αPD-L1 synergistic therapy not only effectively inhibited the growth of primary tumors, but also significantly inhibited the mimic distant tumors as well as lung metastases.PD-L1 blockade immunotherapy was enhanced by RD@MBs delivery system.

Experimental Study on Combined Column of Steel Pipe

Liang Zheng,Shengrun Dou,Wen Wang,Ying Gao,Hongwei Gai 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

To study the properties of various steel-pipe combined columns, ten steel pipe combined columns were designed, including fi ve axial compression specimens and fi ve eccentric compression specimens. The test mainly investigated the infl uence of the combination of a fl ange steel pipe and web steel pipe on the combined column, including the overall failure mode, local failure mode, load–displacement curve, bearing capacity, and stability of the fl ange steel pipe and web steel pipes. The test results showed that the overall and local failure modes of the axial compression specimens with diff erent steel pipe combinations were diff erent. The failure modes of the eccentric compression specimens with diff erent steel pipe combinations were almost identical. Except for the eccentric compression specimen PZH2, none of the other eccentric compression specimens exhibited local buckling. The combination of the fl ange steel pipes and web steel pipes near the fl ange steel pipes had an obviously eff ect on the bearing capacity, while the combination of steel pipes in the middle of the web had a lower eff ect on the bearing capacity. During the loading process, the fl ange and web steel pipe did not lose stability, and the weld between the steel pipes of the axial compression specimen and the eccentric compression specimen was not damaged. There was no obvious separation between the unwelded parts of the steel pipes.

Effects of clearance flow on the characteristics of centrifugal pump under low flow rate

Lulu Zheng,Xiaoping Chen,Hua-Shu Dou,Wei Zhang,ZuChao Zhu,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

The Reynolds averaged Navier-Stokes equations and the shear stress transport k-ω turbulence model are employed to simulate the centrifugal pump with or without clearance flows. The simulation results have been compared with the experimental data and good agreement has been achieved. Results show that clearance flow causes a decrease in the characteristics of the centrifugal pump, particularly in pressure fluctuation. The largest deviation of the amplitude of pressure fluctuation between the centrifugal pump with and without clearance flow is 65.34 %. The numerical results also show that the clearance flow causes collision impact with the mainstream flow and forms a multiple vortex structure at the impeller entrance. Clearance flow greatly affects the pressure distribution in the impeller passage, which is opposite to the volute tongue, especially at the suction side of the blade surface. The wave distribution decreases along the direction of the hub to the shroud, which indicating that the influence of clearance flow weakens along this direction.

Association Between Nasal Colonization of Staphylococcus aureus and Eczema of Multiple Body Sites

Guo Yang,Dou Xia,Chen Xiao-Fan,Huang Cong,Zheng Ying-Jie,Yu Bo 대한천식알레르기학회 2023 Allergy, Asthma & Immunology Research Vol.15 No.5

Purpose: Staphylococcus aureus is the critical pathogenic bacterium of eczema. The relationship between nasal colonization by S. aureus and eczema has not been well studied. We aimed to evaluate the associations between nasal colonization by S. aureus and eczema of multiple body sites, including persistent and ever-reported eczema. We further examined the associations between eczema and different subtypes of S. aureus, that is, methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA). Methods: The real-world data from the US National Health and Nutrition Examination Survey were used. The associations were calculated using survey-weighted multinomial logistic regression models and further calculated in subgroups stratified by demographic factors. Results: In total, 2,941 adults were included. The prevalence rate of S. aureus nasal carriage was significantly higher in adults with persistent hand eczema (51.0%) than in those with ever-reported hand eczema (23.3%) and never eczema (26.9%). S. aureus nasal colonization was associated with an approximately two-fold increased risk of persistent hand eczema (odds ratios ranges in different models: 2.86–3.06) without significant heterogeneity in the association by demographic factors. No significant associations between S. aureus nasal colonization and persistent eczema of other body sites or ever-reported eczema of multiple body sites (including hands) were observed. Furthermore, similar significant association between nasal colonization of MSSA and persistent hand eczema was seen; the association was much stronger (odds ratios ranges in different models: 4.64–6.54) for MRSA, although with borderline significant. Conclusions: Nasal colonization of S. aureus was associated with increased risk of persistent hand eczema. Our findings imply that preventive measures targeting S. aureus for the anterior nares should be considered in preventing and treating eczema.

Research on Multiband Impulse Radio UWB System based on PSWF in Multipath Fading Channel

Chen Lili,Dou Zheng,Yan Li,Lin Yun 보안공학연구지원센터(IJSIP) 2013 International Journal of Signal Processing, Image Vol.6 No.6

Reinforcement Learning-Based Intelligent Decision-Making for Communication Parameters

Xia. Xie,Zheng Dou,Yabin Zhang 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.9

The core of cognitive radio is the problem concerning intelligent decision-making for communication parameters, the objective of which is to find the most appropriate parameter configuration to optimize transmission performance. The current algorithms have the disadvantages of high dependence on prior knowledge, large amount of calculation, and high complexity. We propose a new decision-making model by making full use of the interactivity of reinforcement learning (RL) and applying the Q-learning algorithm. By simplifying the decision-making process, we avoid large-scale RL, reduce complexity and improve timeliness. The proposed model is able to find the optimal waveform parameter configuration for the communication system in complex channels without prior knowledge. Moreover, this model is more flexible than previous decision-making models. The simulation results demonstrate the effectiveness of our model. The model not only exhibits better decision-making performance in the AWGN channels than the traditional method, but also make reasonable decisions in the fading channels.

Lumbar Endoscopic Unilateral Laminotomy With Bilateral Decompression Surgery in Severe Lumbar Stenosis Under Electrophysiological MonitoringFocused on Full-Visualized Trephine/ Osteotome

Ning-Ning Dou,Hao-lin Wang,Shao-Zhen Hu,Zheng-Nan Huang,Jun Zhong,Shi-Ting Li 대한척추신경외과학회 2023 Neurospine Vol.20 No.3

Objective: Although endoscopic drill has the advantages in manipulation and hemostasis, whose low efficiency and blurred vision reduce the efficacy of lumbar endoscopic unilateral laminotomy with bilateral decompression (LE-ULBD). The present study was designed to evaluate the safety and efficacy of full-visualized trephine/osteotome in the LE-ULBD surgery for severe lumbar stenosis. Methods: Fifty-seven severe lumbar stenosis patients who underwent LE-ULBD between January 2020 to January 2023 were enrolled, who were divided into drill and visualized trephine groups. The medical records including demographics, operative duration, intraoperative electrophysiological findings, postoperative hospital stay or hospital stay, postoperative outcomes and complications were retrospectively reviewed and analyzed. Results: A total of 57 patients included 15 in drill and 42 in trephine group were enrolled in the study. There was significant difference in the pre- and postoperative visual analogue scale and Oswestry Disability Index scores in both groups (p < 0.05). The mean operative duration in the trephine group (101.05 ± 12.18 minutes) was shorter than that in the drill group (134.67 ± 9.68 minutes) (p < 0.05). There was no statistical difference between the 2 groups in electrophysiological monitoring, posthospital stays, postoperative outcomes and complications. Abnormal free-electromyography (EMG) were recorded in 2 (13.3%) and 5 patients (11.9%) in the drill and trephine group. Intraoperative somatosensory evoked potential changes occurred in 3 (20%) and 3 patients (7.1%) in the drill and trephine group and all patients recovered immediately when surgery ended. No serious complications and recurrence occurred in all the patients. Conclusion: Full-visualized trephine/osteotome has been approved to be convenient, safe and efficient in our study, which combined with translaminar inside-out technique and EMG monitoring especially free-EMG may offer a new choice in LE-ULBD surgery for lumbar stenosis patients.