Main Patch Research Articles

Ecosystem dynamics in the Liguro-Provençal Basin: the role of eddies in the biological production.

We study numerically the role of mesoscale structures in the Ligurian Sea (NW Mediterranean Sea) as a possible factor affecting the spatial distribution of the chlorophyll spring bloom. We use the Regional Ocean Modeling System (ROMS) configured for the NW Mediterranean Sea (ROMS_NWMed) and satellite derived Altimetric, Sea Surface Temperature and Chlorophyll concentration data, for years 2009 and 2010. Comparison of model output with satellite and in situ data shows agreement between numerical results and observations. There is a significant interannual variability in concentration and distribution of chlorophyll in the basin during the two years of the study. The ROMS_NWMed simulation reveals the formation of a number of mesoscale eddies along the Northern rim Current characterized by a long lifetime and closed streamlines. A significant higher number of eddies is found during the chlorophyll-rich year 2010. The high number of eddies, due to the “eddy pumping mechanism”, generate spatially and temporally localised fluxes of nutrient into the euphotic zone, thus contributing to the fertilization of the Ligurian Sea. Therefore, eddies in the Ligurian rim current can have important effects on the location of development of the main patch of chlorophyll spring bloom and consequently on the local ecosystem dynamics.

A Coplanar Waveguide Fed Rectangular Reconfigurable Patch Antenna with Switchable Strips for Polarization Diversity

A compact single feed rectangular patch antenna with reconfigurable circular polarization has been proposed in this paper. The basic antenna structure is a rectangular patch of dimensions 10 mm x 15 mm printed on a thin FR4 substrate of thickness 3 mm. Two rectangular strips are connected through switches at sideways of the main patch to get polarization diversity. The polarization of the proposed antenna can be reconfigured between left hand circular polarization (LHCP) and right hand circular polarization (RHCP) by the current path, which is changed by operating the switches in ON and OFF modes. The antenna is designed and simulated using IE3D MoM based electromagnetic simulator. The simulated results show good return loss, radiation pattern, axial ratio and acceptable gain at the operating frequency. The antenna has around 15 % effective impedance bandwidth over 4.0 GHz - 4.8 GHz frequency band at a maximum gain of 3.0 dBi with polarization diversity. Defence Science Journal, Vol. 64, No. 1, January 2014, DOI:10.14429/dsj.64.4807

Design of patch antenna on LTCC substrate with broadband and high gain at millimetre wave band

A new antenna structure with broadband and high gain at the millimetre wave bands is presented. This antenna consists of a conventional patch fabricated on a thick low-temperature cofired ceramic (LTCC) substrate. By introducing an inner ground plane surrounding the main patch, the propagation of the surface wave is prevented, and antenna gain is increased. Furthermore, the bandwidth of this antenna becomes wider due to the coupling between the main patch resonator and the newly introduced dielectric resonator. The simulated results of the proposed antenna show a bandwidth and peak antenna gain at 60 GHz of 12 GHz and 9.4 dBi, respectively.

Diegogattaite, Na2CaCu2Si8O20·H2O: a new nanoporous copper sheet silicate from Wessels Mine, Kalahari Manganese Fields, Republic of South Africa

AbstractDiegogattaite (IMA2012-096), Na2CaCu2Si8O20·H2O, is a new mineral from the Wessels mine in the Kalahari manganese fields of South Africa. It occurs as a minor phase with other copper-bearing silicates, Cu-rich pectolite, sugilite, quartz, aegirine and undifferentiated Fe-Mn oxides. Diegogattaite is pale turquoise through teal blue. It is found as sub-mm sized grains in a main crystalline patch 3–4 mm in size, and is currently known from only one sample. The mineral is transparent with a vitreous lustre and may have a good cleavage on {001}. It is brittle, with an uneven fracture and a very pale-blue streak. It is non-fluorescent in short- and long-wave UV light and has an estimated Mohs hardness of ∼5–6. Diegogattaite is biaxial (–), α = 1.598(2), β = 1.627(2), γ = 1.632(2); 2Vmeas = 44.0(6)°, 2Vcalc = 44.5°; dispersion: strong r < v, orientation: X = b, Y ≈ ⊥(001), Z ≈ a; pleochroism X colourless << Y ≈ Z blue green. The calculated density is 3.10 g/cm3. Electron-microprobe analysis gave: Na2O 8.07, CaO 7.3, CuO 20.5, FeO 0.36, SiO262.4, H2O(calc) 2.34, total 100.97 wt.%. A charge-balanced formula on the basis of 21 oxygen a.p.f.u. is: Na2.00Ca1.00Cu1.98Fe0.04Si7.99H2O21. Diegogattaite is monoclinic, space group C2/m, a = 12.2439(6) Å, b = 15.7514(4) Å, c = 10.6008(3) Å, β = 125.623(2)°, V = 1661.87(10) Å3 and Z = 4. The five strongest lines in the X-ray powder pattern are [dobs in Å (Iobs)(hkl)]: 4.25(75)(002,22,220), 3.951(77)(040), 3.261(100)(31,13), 2.898(89)(042,03,003), 2.332(66)(331,43,62,260,043). The crystal structure of diegogattaite was determined by single-crystal X-ray diffraction to final agreement indices of R1 = 0.027, wR2 = 0.071 and GoF = 1.090. It represents a completely new silicate topology based upon a double-sheet of SiO4 tetrahedra composed of connected 6482 cages. The structure of diegogattaite is related to those of synthetic nanoporous Na-Cu-Si-O-(OH)-H2O (CuSH) compounds, which are of interest to the solid-state chemistry community as potential ion-exchangers, catalysts and molecular sieves. The structure of diegogattaite forms a bridge between these structures and those of the gillespite-group minerals, including wesselsite. The close spatial association of wesselsite and diegogattaite suggests a possible reaction between them that may point to a synthetic route for the production of novel alkaline-earth-based nanoporous copper silicates.

Predicting the distribution of potential natural vegetation based on species functional groups in fragmented and species-rich forests

Background and aims – Potential natural vegetation (PNV) can provide a basic reference in guiding the restoration activities for damaged landscapes. Our aim was to find a practicable approach of reconstructing PNV based on functional groups (FGs) in species rich and fragmented forest region. Methods – A total of 149 sample plots (20 × 20 m) were laid and investigated systematically by 1 × 1 km or 1 × 2 km grids across the 482 km 2 forest region in Bawangling nature reserve, Hainan Island, China. The 579 woody plant species found were aggregated into eight functional groups (FGs) according to successional status and potential maximum height. The ecological niche model (MaxEnt) was adopted in predicting the potential distribution of the FGs. The relationship between occurrence probability of FGs and environmental factors was determined as a function of the predicted response curves. The PNV was produced by the overlay of maps for the potential distribution of the FGs, while referring the FGs interactions. Key results – The predicted pioneer FGs scattered widely in the whole landscape, while climax FGs mainly distributed in the central and south part of the study region. Pioneer FGs could better withstand environmental change and occurred in warmer and drier sites, while climax FGs are distributed in cooler and wetter conditions. The PNV could be reconstructed by considering interactions among the FGs. Sixteen main functional patch types were reconstructed in the tropical forest landscape, among which twelve were dominated by climax FGs, accounting for 72.7% of the area, and only four were dominated by pioneer FGs, and accounting for 18.8% of the area. Conclusion – We produced successful prediction of the observed PNV by applying a niche-based model (MaxEnt) based on FGs in fragmented and species rich forest region. This is helpful for predicting how PNV will change to natural and anthropic stressors.

Polarization Reconfigurable Patch Antenna for Wireless Sensor Network Applications

Polarization reconfigurable microstrip patch antenna is presented for 2.4–2.5 GHz wireless sensor network and WLAN applications. Dual feed degenerate mode patch is used as the starting point for circular polarization and L-shaped islands which can be connected or disconnected to the main patch via RF switches are placed around the patch. When L-shape structure is connected, the patch radiates in linear polarization modes with either vertical or horizontal polarization depending on the feed being used. When RF switches are not biased, the antenna is in circular polarization mode. Full wave simulations and measurements were carried out to validate the design.

Estrogen receptor-mediated induction of ABCG2 transporter by mitoxantrone in rat placental trophoblast cells

A research cruise in the North Atlantic during the annual diatom bloom provided an ideal platform to study chlorophyll-a (chl-a) transformations associated with a large scale diatom bloom and export below the photic zone. On one deployment, Lagrangian sediment traps captured a significant flux of aggregated diatom cells produced during the termination of the main bloom. We examined the distribution of chl-a transformation products in sinking particles from the sediment traps and in suspended particles from the water column using high-resolution HPLC with multistage mass spectrometry (LC–MSn). There was a dramatic change in the distribution of chl-a and its transformation products between the pre-sinking period, when the average chl-a concentration integrated over the upper 50 m was 68 ± 36 mg m− 2, and the post-sinking period, when it was 30 ± 11 mg m− 2. Before the diatom bloom left the euphotic zone (pre-sinking), suspended particles contained a considerably higher percentage of pheophorbide-a and other chl-a transformation products (27%) than during the post-sinking period (10%). Despite high levels of spatial variability in the chl-a concentration, and despite sampling from both within and outside a main bloom patch, the chl-a transformation products in suspended particles did not exhibit spatial variability. Sinking particles associated with the diatom bloom export had low POC:chl-a ratios (52–97), suggesting undegraded phytoplankton cells. However, the samples with especially low POC:chl-a ratios exhibited similar distributions of chl-a transformation products to those with a higher ratio. The proportions of demetalated and de-esterified transformation products increased with depth of suspended particles, although significant levels of these products were also found in the uppermost 20 m during the bloom. This suggests processes in both surface waters and through the water column led to the formation of these products.

A U-Shaped UWB Antenna with Band-Notched Performance

An ultra-wideband antenna with controllable band-notched is presented. Two semi-ellipses with different radiuses are subtracted to result in the main patch. By varying inner and outer radiuses, much more enhancement in bandwidth occurred. A U-shaped slot is used to make band-stop performance. Measured S11 is ≤-10 dB over 2.3 - 5 GHz and 6.1 - 15.1 GHz.

Compact Printed Multiband Antenna With Independent Setting Suitable for Fixed and Reconfigurable Wireless Communication Systems

This paper presents the design of a low-profile compact printed antenna for fixed frequency and reconfigurable frequency bands. The antenna consists of a main patch, four sub-patches, and a ground plane to generate five frequency bands, at 0.92, 1.73, 1.98, 2.4, and 2.9 GHz, for different wireless systems. For the fixed-frequency design, the five individual frequency bands can be adjusted and set independently over the wide ranges of 18.78%, 22.75%, 4.51%, 11%, and 8.21%, respectively, using just one parameter of the antenna. By putting a varactor (diode) at each of the sub-patch inputs, four of the frequency bands can be controlled independently over wide ranges and the antenna has a reconfigurable design. The tunability ranges for the four bands of 0.92, 1.73, 1.98, and 2.9 GHz are 23.5%, 10.30%, 13.5%, and 3%, respectively. The fixed and reconfigurable designs are studied using computer simulation. For verification of simulation results, the two designs are fabricated and the prototypes are measured. The results show a good agreement between simulated and measured results.

A Compact UWB Microstrip Antenna with Modified Ground Plane for Bandwidth Enhancement

This paper presents a bandwidth enhancing technique using a modified ground plane with diagonal edges, L-shaped slot and parasitic patches with main patch for the design of compact antennas. The proposed low-cost, compact-size rectangular patch antenna on 4.7 cm × 3.6 cm printed circuit board (FR-4) is designed and validated through simulations and experiments. Results show that the ground plane with Lshaped slot in presence of the diagonal cuts at the top corners and the rectangular parasitic patches can increase the bandwidth. Return losses of −23.6 dB and −29.7 dB for the first and second resonant frequencies, respectively, can be achieved when the depth of the diagonal cut is 3 mm, the dimension of each rectangular parasitic patch is 10 mm×3.5 mm, and the L-shaped slot size is 7.5 mm ×2.5mm, providing a 41.27% wider bandwidth than Federal Communication Commission’s(FCC) standard. General Terms Designing of Microstrip Antenna.

Model simulations on the long-term dispersal of 137Cs released into the Pacific Ocean off Fukushima

A sequence of global ocean circulation models, with horizontal mesh sizes of 0.5°, 0.25° and 0.1°, are used to estimate the long-term dispersion by ocean currents and mesoscale eddies of a slowly decaying tracer (half-life of 30 years, comparable to that of 137Cs) from the local waters off the Fukushima Dai-ichi Nuclear Power Plants. The tracer was continuously injected into the coastal waters over some weeks; its subsequent spreading and dilution in the Pacific Ocean was then simulated for 10 years. The simulations do not include any data assimilation, and thus, do not account for the actual state of the local ocean currents during the release of highly contaminated water from the damaged plants in March–April 2011. An ensemble differing in initial current distributions illustrates their importance for the tracer patterns evolving during the first months, but suggests a minor relevance for the large-scale tracer distributions after 2–3 years. By then the tracer cloud has penetrated to depths of more than 400 m, spanning the western and central North Pacific between 25°N and 55°N, leading to a rapid dilution of concentrations. The rate of dilution declines in the following years, while the main tracer patch propagates eastward across the Pacific Ocean, reaching the coastal waters of North America after about 5–6 years. Tentatively assuming a value of 10 PBq for the net 137Cs input during the first weeks after the Fukushima incident, the simulation suggests a rapid dilution of peak radioactivity values to about 10 Bq m−3 during the first two years, followed by a gradual decline to 1–2 Bq m−3 over the next 4–7 years. The total peak radioactivity levels would then still be about twice the pre-Fukushima values.

Reassessment of the source of the 1976 Friuli, NE Italy, earthquake sequence from the joint inversion of high-precision levelling and triangulation data

SUMMARY In this study, we revisit the mechanism of the 1976 Friuli (NE Italy) earthquake sequence (main shocks Mw 6.4, 5.9 and 6.0). We present a new source model that simultaneously fits all the available geodetic measurements of the observed deformation. We integrate triangulation measurements, which have never been previously used in the source modelling of this sequence, with high-precision levelling that covers the epicentral area. We adopt a mixed linear/non-linear optimization scheme, in which we iteratively search for the best-fitting solution by performing several linear slip inversions while varying fault location using a grid search method. Our preferred solution consists of a shallow north-dipping fault plane with assumed azimuth of 282° and accommodating a reverse dextral slip of about 1 m. The estimated geodetic moment is 6.6 × 1018 Nm (Mw 6.5), in agreement with seismological estimates. Yet, our preferred model shows that the geodetic solution is consistent with the activation of a single fault system during the entire sequence, the surface expression of which could be associated with the Buia blind thrust, supporting the hypothesis that the main activity of the Eastern Alps occurs close to the relief margin, as observed in other mountain belts. The retrieved slip pattern consists of a main coseismic patch located 3–5 km depth, in good agreement with the distribution of the main shocks. Additional slip is required in the shallower portions of the fault to reproduce the local uplift observed in the region characterized by Quaternary active folding. We tentatively interpret this patch as postseismic deformation (afterslip) occurring at the edge of the main coseismic patch. Finally, our rupture plane spatially correlates with the area of the locked fault determined from interseismic measurements, supporting the hypothesis that interseismic slip on the creeping dislocation causes strain to accumulate on the shallow (above ∼10 km depth) locked section. Assuming that all the long-term accommodation between Adria and Eurasia is seismically released, a time span of 500–700 years of strain-accumulating plate motion would result in a 1976-like earthquake.

높은 격리 특성을 갖는 이중 급전 방식 초소형 중계기용 안테나

In this paper, a dual-fed small ICS repeater antenna with high isolation is designed, fabricated, and measured. Bandwidth and gain are optimized by changing the stub lengths near main patch and power divider, and also by changing the size of parasitic patch. To improve the isolation characteristic of the antenna, a dual-feeding method is applied in designing the antenna. The fabricated antenna has a VSWR less than 2, a gain over 7 dBi, and an isolation between the donor and the server antennas less than -65 dB from 1,920~2,170 MHz for 3G mobile communication.

Broadband E‐shaped microstrip antenna with dipole RE‐radiators

AbstractNew design of microstrip patch antenna with coaxial feed is proposed in this article. The proposed construction includes additional dipole radiators placed over main patch and exhibits enhanced broadbandness comparing to classical E‐shaped patch antenna. Also, gain of proposed antenna is highly stable in the broad frequency band. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1785–1788, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26947

A Vertical Transition Between Rectangular Waveguide and Coupled Microstrip Lines

In this letter, a novel transition between a rectangular waveguide and coupled microstrip lines is presented. A differential microstrip patch antenna (DMPA) inside the waveguide acts as a radiation element. The antenna is composed of the main patch, the short-end parasitic patch, and the matching network. By implementing the short-end parasitic patch, the bandwidth of differential mode signals is greatly increased, while transmission of common mode signals is strongly suppressed. Back-to-back arrangements of such a transition were fabricated and measured. The results show that the 10 dB return loss bandwidth reaches 14.5 GHz, and the insertion loss at the center frequency (96 GHz) is 0.5 dB. Such a transition is suitable for numerous millimeter-wave applications.

보우-타이 모노폴 UWB 안테나의 소형화 및 대역 저지 특성

본 논문에서는 대역 저지 특성을 갖는 소형화된 보우-타이 모노폴 UWB 안테나를 제안하였다. 기존의 보우-타이 모노폴 안테나에 완전 자계벽(PMW) 조건을 적용하여 안테나의 물리적 크기를 소형화하였다. 임피던스 정합을 위해 접지면의 굴곡각을 조절하였고, 테이퍼 형태의 급전 선로를 적용하였으며, 패치면의 모서리를 잘라 내었다. UWB 대역 내에 존재하는 타 대역의 간섭을 저지하기 위해 패치면에 <TEX>${\lambda}/4$</TEX> 슬롯 공진기를 삽입하였다. 제작된 안테나는 비유전율 6.15를 갖는 Taconic RF60-A 기판을 사용하였다. 제안된 안테나의 크기는 <TEX>$30.0{\times}39.7mm^2$</TEX>로 기존 보우-타이 모노폴 안테나의 약 45 %가 줄어들었다. UWB 전체 대역에서 -10 dB 이하의 반사 손실 특성과 5 GHz WLAN 대역의 저지 특성을 나타내었다. -1~5 dBi의 최대 이득 및 1.0 ns 이내의 군지연 변화 특성과 x-y평면의 방사 패턴에서 지향성을 나타냈다. In this paper, a miniaturized bow-tie monopole UWB antenna with band rejection characteristic is proposed. To miniaturize the proposed antenna, a perfect magnetic wall(PMW) condition is applied to primitive bow-tie monopole antenna. An uneven ground patch, a tapered feeding structure and a edge-chopped main patch are adapted for impedance matching. A quater-lambda slot resonator is inserted at main patch to prevent interference in UWB band from another band. The proposed antenna is fabricated on Taconic RF60-A substrate with relative permittivity of 6.15. The size of the proposed antenna is <TEX>$30.0{\times}39.7mm^2$</TEX>, which is only 45 % of the conventional bow-tie monopole antenna. The proposed antenna covers full UWB band with return losses less than -10 dB and has band stop characteristic in 5 GHz WLAN band. The maximum gains are within -1.0~5.0 dBi, the group delay variations are within 1.0 ns and the radiation patterns show directivity characteristics in x-y plane.

Space‐time distribution of afterslip following the 2009 L'Aquila earthquake

The inversion of multitemporal DInSAR and GPS measurements unravels the coseismic and postseismic (afterslip) slip distributions associated with the 2009 MW 6.3 L'Aquila earthquake and provides insights into the rheological properties and long‐term behavior of the responsible structure, the Paganica fault. Well‐resolved patches of high postseismic slip (10–20 cm) appear to surround the main coseismic patch (maximum slip ≈1 m) through the entire seismogenic layer above the hypocenter without any obvious depth‐dependent control. Time series of postseismic displacement are well reproduced by an exponential function with best‐fit decay constants in the range of 20–40 days. A sudden discontinuity in the evolution of released postseismic moment at ≈130 days after the main shock does not correlate with independent seismological and geodetic data and is attributed to residual noise in the InSAR time series. The data are unable to resolve migration of afterslip along the fault probably because of the time interval (six days) between the main shock and the first radar acquisition. Surface fractures observed along the Paganica fault follow the steepest gradients of postseismic line‐of‐sight satellite displacements and are consistent with a sudden and delayed failure of the shallow layer in response to upward tapering of slip. The occurrence of afterslip at various levels through the entire seismogenic layer argues against exclusive depth‐dependent variations of frictional properties on the fault, supporting the hypothesis of significant horizontal frictional heterogeneities and/or geometrical complexities. We support the hypothesis that such heterogeneities and complexities may be at the origin of the long‐term variable behavior suggested by the paleoseismological studies. Rupture of fault patches with dimensions similar to that activated in 2009 appears to have a ≈500 year recurrence time interval documented by paleoseismic and historical studies. In addition to that, paleoseismological evidence of large (&gt;0.5 m) coseismic offsets seems to require seismic events, recurring every 1000–2000 years, characterized by (1) multisegment linkage, (2) surface ruptures larger than in 2009, and (3) complete failure of the 2009 coseismic and postseismic patches.

Directly-fed single-layer wideband RFID reader antenna

A wideband circularly-polarised (CP) antenna with a simple structure is proposed for universal ultra-high frequency (UHF) radio-frequency identification (RFID) reader applications. The antenna is composed of two patches, an L-shaped ground and an SMA connector. The main patch which is truncated to generate CP radiation is fed directly by the SMA connector oriented in the same plane via the vertical part of the L-shaped ground. The parasitic patch used to enhance the bandwidth is placed at the same layer of the main patch. These two schemes realised a directly-fed single-layer structure. The 3 dB axial ratio bandwidth and impedance matching bandwidth for 14 dB return loss overlap within the universal UHF RFID band (840–960 MHz), while high gain with an average level of 7.3 dBi is achieved. Simulation and measurements are in good agreement.

Design of antenna with broadband and high gain at millimetre-wave band

A new antenna structure with broadband and high gain at the millimetre-wave bands is presented. This antenna consists of a conventional patch and a new guard ring resonator. By introducing the guard ring resonator, the propagation of the surface wave is prevented, and antenna gain is increased. Furthermore, the bandwidth of this antenna becomes wider due to the coupling of the guard ring resonator with the main patch resonator. The simulated results of the proposed antenna show a bandwidth and peak antenna gain at 60 GHz of 7GHz and 9.6 dBi, respectively.

Fault geometry, coseismic-slip distribution and Coulomb stress change associated with the 2009 April 6, Mw 6.3, L’Aquila earthquake from inversion of GPS displacements

The 2009 April 6, Mw= 6.3 L’Aquila earthquake occurred within a complex system of NW-SE trending normal faults in the Abruzzi Central Apennines (Italy). We analyse the coseismic deformation as measured by >70 global positioning system (GPS) stations, both from continuous and survey-mode networks, providing unprecedented details for a moderate normal faulting earthquake in Italy from GPS measurements. We use rectangular, uniform-slip, dislocations embedded in an elastic, homogeneous and isotropic half-space and a constrained, non-linear optimization algorithm, to solve for the best-fitting rectangular dislocation geometry and coseismic-slip distribution. We use a bootstrap approach to investigate uncertainties in the model parameters and define confidence bounds for all the inverted parameters. The rupture occurred on a N129°E striking and 50° southwestward dipping normal fault, in agreement with geological observations of surface breaks along the Paganica fault. Our distributed slip model exhibits a zone of relatively higher slip (>60 cm) between ~1.5 and ~11 km depth, along a roughly downdip, NW-SE elongated patch, confined within the fault plane inverted assuming uniform-slip. The highest slip, of the order of ~1 m, occurred on a ~16 km2 area located at ~5 km depth, SE of the mainshock epicentre. The analysis of model resolution suggests that slip at depth below ~5 km can be resolved only at a spatial scale larger than 2 km, so a finer discretization of different asperities within the main patch of coseismic-slip is not allowed by GPS data. We compute the coseismic Coulomb stress changes in the crustal volume affected by the major aftershocks, and compare the results obtained from the uniform-slip and the heterogeneous-slip models. We find that most of the large aftershocks occurred in areas of Coulomb stress increase of 0.2-13 bar and that a deepening of the slip distribution down to a depth greater than 6 km in the SE part of the fault plane, in agreement with the inverted slip model, can explain the deepest, April 7, Mw 5.3 aftershock.