Performance Analysis of a Two-Hop Fixed-Gain MIMO Multiuser Relay Network with End-to-End Antenna Selection

Guangping Li,Steven David Blostein,Guangchi Zhang,Jiuchao Feng 한국전자통신연구원 2012 ETRI Journal Vol.34 No.2

This letter analyzes the performance of a two-hop MIMO multiuser relay network with a fixed gain amplify-and-forward protocol and antenna selection at the transmitter and receiver. A new expression for the cumulative distribution function of the highest instantaneous end-to-end signal-to-noise ratio is derived. Based on the above result, closed-form expressions for outage probability and bit error rate are presented. Also, the diversity order of the system is determined. Finally, computer simulations are compared to the analytical results, and insights and observations are provided.

Identification of putative olfactory genes in newly hatched larvae of a Coleopteran ectoparasitoid Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) by transcriptome analysis

Li Xiaojuan,Dong Guangping,Fang Jianmin,Liu Hongjian,Guo Wanlin,Yin Huayang 한국곤충학회 2020 Entomological Research Vol.50 No.7

Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an effective ectoparasitoid of pine sawyer beetle Monochamus alternatus Hope (Coleoptera: Cerambycidae) which is the major median insect for transmission of pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle (Aphelenchida: Parasitaphelenchidae). A sensitive and acute olfactory system is extremely essential for newly hatched larva of D. helophoroides to forage for a host. Therefore, we established the transcriptome of newly hatched D. helophoroides larvae and characterized the expression profiles of olfactory genes. We identified 20 transcripts encoding putative odorant binding proteins (OBPs), 11 putative chemosensory proteins (CSPs), 9 putative odorant receptors (ORs), 11 putative ionotropic receptors (IRs), 7 putative gustatory receptors (GRs) and 4 putative sensory neuron membrane proteins (SNMPs) olfactory genes from the transcriptome of newly hatched D. helophoroides larvae. According to the phylogenetic analysis, 3 OBPs (DhelOBP6, DhelOBP14 and DhelOBP19), 1 CSP (DhelCSP11), 1 OR (DhelOrco1), 3 IRs (DhelIR3, DhelIR6 and DhelIR8), 3 GRs (DhelGR2, DhelGR4 and DhelGR5) and 2 SNMPs (DhelSNMP1 and DhelSNMP3) had high similarities with reported Coleopteran species. The highest expressed olfactory gene was DhelCSP3, followed by DhelOBP8 and DhelCSP2. The expression levels of the majority of OR, IR, GR and SNMP genes were low. These results indicate that CSPs and OBPs may play important roles in the olfactory recognition process in newly hatched D. helophoroides larvae. The findings from the present study are helpful in unraveling the profound mystery between D. helophoroides and M. alternatus, as well as improving the parasitism efficiency of D. helophoroides larvae.

Effect of glass cooling rate on the crystallization behavior and structure of Al2O3-SiO2-Na2O-CaF2 oxyfluoride glass-ceramics

Mengxuan Li,Jinxin Zou,Guangping Guo,Jianxiang Liu,Guicheng Wang 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.5

The glass cooling rate during molding process has significant effect on the crystallization behavior and structural uniformityof Al2O3-SiO2-Na2O-CaF2 oxyfluoride glass-ceramics. Abaqus Finite Element Analysis indicated that at room temperaturecooling environment, the cooling rate of 8mm thick glass was notably lower than that of 3 mm thick glass. The interiortemperature of 8 mm thick precursor glass was still above 710 oC even after the sample was cooled for 15 s, which caused theformation of “crystal stones” in precursor glass. The microstructure of oxyfluoride glass and glass-ceramics with differentthickness was analyzed by using DTA, XRD, IR and SEM. Since the 8 mm thick glass was cooled slowly, the initial crystalnucleation generated in the interior of glass, mixed crystal phases were formed in the interior after heat treatment, while singleCaF2 crystal phase formed on the surface. On the contrary, there was only uniform CaF2 crystal phase generating in the 3mm thick precursor glass after heat treatment, as a result of high cooling rate during molding process. Besides, the mechanismand ways to optimize the structure uniformity of glass ceramics were also be discussed.

Efficiently visible and 2 μm infrared emission in K2YbF5: Ce3+/Ho3+ microcrystals

Hao Dong,Guangping Zhu,Min Zhang,Kai Dai,Qiang Li,Chaopeng Cui 한국물리학회 2020 Current Applied Physics Vol.20 No.6

Ho3+/Ce3+ co-doped K2YbF5 microcrystals were synthesized by solvent-thermal method. Under excitation of 980 nm laser diode, effectively visible and 2 μm-infrared luminescence of Ho3+ ion were obtained in the microcrystals. By changing Ce3+-ion doping concentration, the luminescence properties of visible and 2 μm emission were effectively regulated. At low Ce3+-ion doping level, the red and green upconversion emission obviously increases and decreases respectively with the increase of Ce3+-ion amount in the samples, meanwhile the intensity of 2 μm fluorescence changes very little. At high Ce3+-ion doping level, the intensities of the red and green emission both decrease with the increase of Ce3+-ion concentration, while the 2 μm emission intensity increases obviously. In the sample doped with 16% Ce3+ ion, the intensity of 2 μm emission is about 4.5 times that of the sample without Ce3+ ion, and the corresponding quantum efficiency is about 78.3%. The result is attributed to the influence of the different cross relaxation between Ho3+ and Ce3+ ion in luminescence process at low and high Ce3+-ion doping concentration. The corresponding luminescence mechanism and energy transfer process were discussed in detail.

High Temperature and Pressurized Steaming/Silane Coupling Co-Modification for Wood Fibers and Its Effect on the Properties of Wood Fiber/HDPE Composites

Xun Gao,Qingde Li,Wanli Cheng,Guangping Han,Lihui Xuan 한국고분자학회 2017 Macromolecular Research Vol.25 No.2

Poplar fibers were pretreated under high temperature and pressurized steam at different temperatures and pressures; they were further modified using different amounts of silane coupling agent. The obtained modified fibers were used to prepare wood fiber/high-density polyethylene (HDPE) composites by an extrusion-molding process. The effects of high temperature and pressurized steaming/silane coupling co-modification on the properties of wood fiber/HDPE composites were investigated. The results show that after the high temperature and pressurized steaming treatment, the amount of hydroxyl groups on the surface of the fibers and surface polarity of the fibers decreased, whereas the crystallinity and thermal stability significantly increased. The storage modulus and mechanical properties of the composites improved as well. The addition of silane to the steam-treated fibers further enhanced the storage modulus, loss modulus, and the mechanical properties of the composites. Moreover, when the wood fibers were only modified by adding silane and the silane content was 5%, the prepared composites showed better mechanical properties than the high temperature and pressurized steaming treatment. However, the addition of a small amount of silane to the wood fibers exposed to steam at 170 °C and 0.8 MPa provided even better results; when 2% silane was added, the composites showed the best mechanical properties.

Influence of the properties of corundum aggregates on the strength and slag resistance of refractory castables

Wen Yan,Nan Li,Zheng Miao,Guangping Liu,Yuanyuan Li 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

Three refractory castables containing corundum aggregates with different porosities, average pore size and strength and the same matrices were fabricated. The effects of the properties of corundum aggregates on the strength and slag resistance of refractory castables were investigated through an X-ray diffractometer (XRD), scanning electron microscopy (SEM), mercury porosimetry measurements, etc. It was found that the properties of corundum aggregates have an important effect on the bulk density, porosity, compressive strength and slag resistance of refractory castables, but have little effect on the flexural strength of refractory castables. Compared with a castable containing white fused corundum aggregate (with a porosity of 4.2% and a bulk density of 3.62 g/cm3), the castable containing a porous corundum aggregate (with a porosity of 42.0% and a bulk density of 2.29 g/cm3) has a higher porosity of 35.7%, a lower bulk density of 2.44 g/cm3, a lower but sufficient compressive strength (80.4 MPa) and a lower slag resistance, but has a similar flexural strength (20.3 MPa), and then has a potential application for a non-slag working lining of a ladle to decrease the consumption of energy and Al2O3 material.

Study on tool wear for efficient grooving blisk with disc milling cutter

Qingsi Cheng,Song Wang,Hongmin Xin,Jian Zhang,Changfeng Yao,Minchao Cui,Guangping Li 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

Tool wear has an important influence on machining quality, cost, cutting force and heat. Grooving blisk with disc milling cutter is 3-4 times more efficient than plunge milling and side milling, but the tool wear is serious because of the large milling force and high milling temperature during the machining process. In the study, the damage and wear morphology of the tool was observed by focused ion/double beam system; the wear mechanism was studied by energy spectrum analysis; the tool life curve was drawn by the increase of flank wear. The experimental results show that the main wear and damage morphologies of disc milling cutter are chip sticking to the tool, chip accumulation, edge collapse, peeling, crack, plastic deformation and boundary wear; the main wear mechanism are abrasive wear, adhesive wear, oxidation wear and diffusion wear; the wear rate of the left blade is the fastest, followed by the right blade, and the wear rate of the middle blade is the slowest. These results can provide guidance for iimproving tool life, optimizing tool and mproving machining processes.