Movable Antennas for Wireless Communication: Opportunities and Challenges

Movable antenna (MA) technology is a recent development that fully exploits the wireless channel spatial variation in a confined region by enabling local movement of the antenna. Specifically, the positions of antennas at the transmitter and/or receiver can be dynamically changed to obtain better channel conditions for improving the communication performance. In this article, we first provide an overview of the promising applications for MA-aided wireless communication. Then, we present the hardware architecture and channel characterization for MA systems, based on which the variation of the channel gain with respect to the MA's position is illustrated. Furthermore, we analyze the performance advantages of MAs over conventional fixed-position antennas, in terms of signal power improvement, interference mitigation, flexible beamforming, and spatial multiplexing. Finally, we discuss the main design challenges and their potential solutions for MA-aided communication systems

Low Carbon Energy Policy Research

AbstractCase study of Korea, Low carbon energy efficiency labeling schemes (Energy Efficiency Label and Standard Program, High efficiency Appliance Certification Program, e-Standby Program) play a key role in carrying out the energy efficiency improvement policy in the appliances and equipment sector in Korea. Korea operates these Programs in an effort to improve energy efficiency in appliances and equipments. Mandatory energy efficiency standard which bans production and sales of low energy efficiency products which fall below the minimum energy performance standard. Ministry of Knowledge of Economy (MKE) and Korea Energy Management Corporation (KEMCO) is the key organizations in implementing energy efficiency standards and labeling. National energy efficiency efforts can be realized through energy efficiency improvements with the successful implementation of an energy efficient appliances dissemination policy and the phase out of low efficiency appliances. Through the implementation of the Energy Efficiency Label and Standard Program (1992), High-efficiency Appliance Certification Program (1996) and e-Standby Program (1999), significant energy efficiency improvements have been achieved, and 1.37 billion USD worth of energy savings

The large scale impact of offshore wind farm structures on pelagic primary productivity in the southern North Sea

The increasing demand for renewable energy is projected to result in a 40-fold increase in offshore wind electricity in the European Union by 2030. Despite a great number of local impact studies for selected marine populations, the regional ecosystem impacts of offshore wind farm structures are not yet well assessed nor understood. Our study investigates whether the accumulation of epifauna, dominated by the filter feeder Mytilus edulis (blue mussel), on turbine structures affects pelagic primary productivity and ecosystem functioning in the southern North Sea. We estimate the anthropogenically increased potential distribution based on the current projections of turbine locations and reported patterns of M. edulis settlement. This distribution is integrated through the Modular Coupling System for Shelves and Coasts to state-of-the-art hydrodynamic and ecosystem models. Our simulations reveal non-negligible potential changes in regional annual primary productivity of up to 8% within the offshore wind farm area, and induced maximal increases of the same magnitude in daily productivity also far from the wind farms. Our setup and modular coupling are effective tools for system scale studies of other environmental changes arising from large-scale offshore wind-farming such as ocean physics and distributions of pelagic top predators.Comment: 17 pages, 6 figures, re-revised manuscript submitted to Hydrobiologi

Movable-Antenna Array Enhanced Beamforming: Achieving Full Array Gain with Null Steering

Conventional beamforming with fixed-position antenna (FPA) arrays has a fundamental trade-off between maximizing the signal power (array gain) over a desired direction and simultaneously minimizing the interference power over undesired directions. To overcome this limitation, this letter investigates the movable antenna (MA) array enhanced beamforming by exploiting the new degree of freedom (DoF) via antenna position optimization, in addition to the design of antenna weights. We show that by jointly optimizing the antenna positions vector (APV) and antenna weights vector (AWV) of a linear MA array, the full array gain can be achieved over the desired direction while null steering can be realized over all undesired directions, under certain numbers of MAs and null-steering directions. The optimal solutions for AWV and APV are derived in closed form, which reveal that the optimal AWV for MA arrays requires only the signal phase adjustment with a fixed amplitude. Numerical results validate our analytical solutions for MA array beamforming and show their superior performance to the conventional beamforming techniques with FPA arrays.Comment: Submitted to IEEE Communications Letter

各種要因を考慮したセメント系材料の乾燥収縮挙動に関する研究

コンクリートのひび割れの宿命的な原因として乾燥収縮が挙げられる。そこで様々な要因が乾燥収縮挙動に及ぼす影響を明らかにする必要がある。本研究の目的はセメントの種類，高炉スラグ微粉末（GGBFS）の粉末度，養生材齢，細骨材・粗骨材種類および低減剤（SRA）混和材など様々な要因がセメント系複合材料の乾燥収縮挙動に及ぼす影響を検討することである。また，細孔構造，水和物の気泡組織およびSRA溶液の特徴に基づいてSRAの使用による耐凍害性低下の原因を検討した。１．細骨材種類がモルタルの乾燥収縮に顕著な影響を及ぼすものの，コンクリートに対する影響は顕著ではない。粗骨材のひずみ，細・粗骨材の平均比表面積および直径6-30nmmの粗骨材細孔容積が増加するにともない，コンクリートの乾燥収縮率も増加する。これは粗骨材の特性がコンクリートの乾燥収縮に大きな影響を及ぼすことを示している。また，コンクリートにおける乾燥収縮特性が粗骨材の吸水率，単位水量と骨材の単位量を考慮して求めた全水量と静弾性係数によって影響を受けることを明らかにした。２． 異なるGGBFS粉末度，セメント種類および養生材齢が乾燥収縮特性に及ぼす影響を検討するために行った実験結果からは，乾燥開始材齢７日と28日による収縮量はほとんど認められなかった。しかし，GGBFSがセメントの種類によって乾燥収縮に及ぼす影響が異なり，普通セメントにGGBFSを混和した場合，乾燥収縮量に及ぼす影響は小さいものの，中庸熱，低熱セメントでは，GGBFS粉末度が高いほど収縮量は増大した。また，水蒸気吸着法によってESW理論とBET理論から得られた比表面積は良く一致し，比表面積が大きくなるほど乾燥収縮量が増大する傾向が見られた。モルタルにおいて，直径6-30nmの細孔量が多くなるほど収縮量が増大する傾向がみられた。３． 低い表面張力をもつ収縮低減剤SRA-SとSRA-Hにおいてセメント系複合材料で良好な収縮低減効果が認められた。しかし，アルコール系のSRA-Hでは空気連行性の低下により耐凍害性が低下するということが明らかとなった。また，セメントとSRA種類が変化した場合には乾燥収縮に関与する細孔容積として直径30nm以下に限定することはできなかった。４．統計的手法を用いることで，SRAの有無によるモルタルの乾燥収縮に影響を及ぼす細孔径の範囲が直径10-50nmと20-30nm程度に関連していることを明らかにした。さらに，分散分析法（ANOVA）から乾燥収縮における各要因およびそれらの交互作用によって，乾燥収縮を低減するための最適調合を提案した。中庸熱セメント，GGBFS無混和で，高炉スラグ細骨材を用い，セメント質量に対して2.3％添加量の収縮低減剤を混合したモルタルの収縮率が最も小さいと判定した。Drying shrinkage is a phenomenon that may lead to inevitable cracking in many concrete structures. It is necessary to elucidate the drying shrinkage behavior affected by various influential factors. Therefore, the purpose of this research is to investigate the drying shrinkage behavior of cementitious composites affected by various affecting factors, such as cement type, ground granulated blast furnace slag (GGBFS) fineness, curing age, fine aggregate, coarse aggregate and shrinkage reducing admixture (SRA)admixture. Moreover, the frost resistance degraded due to SRA was also investigated by taking into consideration pore structure and air void system of hydration products and SRA solution characteristics.1. Fine aggregates significantly affect the drying shrinkage in mortar, but concrete. The drying shrinkage strain of concrete specimens proportionally increases with the increase of aggregate shrinkage strain, average specific surface area and pore volume of 6~30nm in diameter of aggregates, which implies the significant influence of aggregate characteristics on drying shrinkage behavior in concrete. It was also found that the drying shrinkage property in concrete can be affected by static modulus of elasticity and total amount of water content, in which the water absorption ratio, unit mass of aggregate and unit water content were considered.2. An experimental research on the effects of ground granulated blast furnace slag (GGBFS) fineness, cement type and curing age on the drying shrinkage and microstructure of GGBFS blended cement mortar was investigated. The test results revealed that the drying shrinkage evolution can be significantly affected by GGBFS powder fineness, cement type, specific surface area and 6~30nm porosity, but curing age (7 days and 28 days). ESW specific surface area (SSA) due to water vapor adsorption isotherm is in a good agreement with BET SSA with a correlation factor of 0.95. Smaller SSA and less pore volume of 6~30nm would decrease effectively the drying shrinkage. As a result of this study, the prediction equation of drying shrinkage is proposed based on ESW SSA, the volume of 6~30nm diameter pore and mass loss.3. Both SRA-S and SRA-H are very effective admixture for reducing cementitious composite due to lower surface tension, but cementitious composites with SRA have poor frost resistance, especially SRA-H. Moreover, frost resistance property could be enhanced by a certain high percent of air content. However, the pore volume involved in the drying shrinkage could not be limited to 30nm in diameter when the cement and SRA types were changed. 4. Through statistical investigation, the pore structure affecting on the drying shrinkage of mortar specimens without SRA and with SRA is related to 10-50nm and 20-30nm, respectively, which could provide a good perspective for the drying shrinkage behavior. Furthermore, by analyzed each factor and their interaction effect in the drying shrinkage by analysis of variance (ANOVA), we determined an optimization experiment design for reducing the drying shrinkage, that is moderate heat cement, without GGBFS admixture, blast furnace slag fine aggregate, SRA with 2.3% dosage by the weight of cement.室蘭工業大学 (Muroran Institute of Technology)博士（工学

Magnetosome Gene Duplication as an Important Driver in the Evolution of Magnetotaxis in the Alphaproteobacteria

The evolution of microbial magnetoreception (or magnetotaxis) is of great interest in the fields of microbiology, evolutionary biology, biophysics, geomicrobiology, and geochemistry. Current genomic data from magnetotactic bacteria (MTB), the only prokaryotes known to be capable of sensing the Earth’s geomagnetic field, suggests an ancient origin of magnetotaxis in the domain Bacteria. Vertical inheritance, followed by multiple independent magnetosome gene cluster loss, is considered to be one of the major forces that drove the evolution of magnetotaxis at or above the class or phylum level, although the evolutionary trajectories at lower taxonomic ranks (e.g., within the class level) remain largely unstudied. Here we report the isolation, cultivation, and sequencing of a novel magnetotactic spirillum belonging to the genus Terasakiella (Terasakiella sp. strain SH-1) within the class Alphaproteobacteria. The complete genome sequence of Terasakiella sp. strain SH-1 revealed an unexpected duplication event of magnetosome genes within the mamAB operon, a group of genes essential for magnetosome biomineralization and magnetotaxis. Intriguingly, further comparative genomic analysis suggests that the duplication of mamAB genes is a common feature in the genomes of alphaproteobacterial MTB. Taken together, with the additional finding that gene duplication appears to have also occurred in some magnetotactic members of the Deltaproteobacteria, our results indicate that gene duplication plays an important role in the evolution of magnetotaxis in the Alphaproteobacteria and perhaps the domain Bacteria

Genetic Evolution and Molecular Selection of the HE Gene of Influenza C Virus

Influenza C virus (ICV) was first identified in humans and swine, but recently also in cattle, indicating a wider host range and potential threat to both the livestock industry and public health than was originally anticipated. The ICV hemagglutinin-esterase (HE) glycoprotein has multiple functions in the viral replication cycle and is the major determinant of antigenicity. Here, we developed a comparative approach integrating genetics, molecular selection analysis, and structural biology to identify the codon usage and adaptive evolution of ICV. We show that ICV can be classified into six lineages, consistent with previous studies. The HE gene has a low codon usage bias, which may facilitate ICV replication by reducing competition during evolution. Natural selection, dinucleotide composition, and mutation pressure shape the codon usage patterns of the ICV HE gene, with natural selection being the most important factor. Codon adaptation index (CAI) and relative codon deoptimization index (RCDI) analysis revealed that the greatest adaption of ICV was to humans, followed by cattle and swine. Additionally, similarity index (SiD) analysis revealed that swine exerted a stronger evolutionary pressure on ICV than humans, which is considered the primary reservoir. Furthermore, a similar tendency was also observed in the M gene. Of note, we found HE residues 176, 194, and 198 to be under positive selection, which may be the result of escape from antibody responses. Our study provides useful information on the genetic evolution of ICV from a new perspective that can help devise prevention and control strategies