Feed Point Research Articles

An Inversion Transformation of Feeding Waveform and Field Distribution on NEMP Simulator

The paper presents an inverse derivation method for the excitation signal of NEMP simulator and the field distribution near the simulator, and only one field measurement system is needed. Transformation functions from feeding point to arbitrary point have been calculated by the simulator’s external shape and the geometrical relationship between simulator and the ground, then with the waveform measured in one point, the excitation signal of NEMP simulator can be obtained, and the field distribution near the simulator can be depicted.

First detection of Vespa velutina nigrithorax (Hymenoptera: Vespidae) in the Balearic Islands (Western Mediterranean): a challenging study case

The yellow-legged hornet, Vespa velutina nigrithorax is an Invasive Alien Species introduced into Europe in 2004, and is currently present in France, Italy, Spain, Portugal, Germany, and Belgium. It was also recently introduced in the United Kingdom and Switzerland. Here we present the first detection of V. velutina in the westernmost Mediterranean islands (Majorca, Balearic archipelago). In October 2015, a specimen of hornet, which was later identified as V. velutina, was sent to the laboratory of Zoology at the University of the Balearic Islands by a beekeeper from the locality of Soller (northwest of Majorca). After the identification, and in coordination with the local authorities, an intensive survey was implemented in the area of first detection using sticky traps baited with protein and nest detection by directly observing the flight route of adult hornets from two or three feeding points. The first nest was detected on 30th October 2015 and was entirely removed. The next year, nine other nests were located from August to November 2016 in the same area and again, all of them were removed entirely. It is the first report on an island of destroying nests as a means of controlling the spread, a scenario very different to mainland Europe. All nests were detected in evergreen tree species (pines, holm oaks, and common cypress) in the “Serra de Tramuntana”, a mountain range located in the north-west of the island of Majorca (3667 km2), which is situated 176 km off the mainland. Considering the presumably early stage of the invasion of V. velutina in Majorca, the size of the island, and the confinement of the detection area, we consider that this species could be eradicated if resources and a specific program for eradication in Majorca are implemented in coordination with all involved partners.

Broadband Circularly Polarized Slot Antenna Array Fed by Asymmetric CPW for C-Band Applications

ABSTRACTIn this manuscript, a new design of broadband circularly polarized (CP) array antenna is presented. A 2 × 2 planar array antenna is accomplished using the proposed CP diamond-shaped slot element with an L-shaped patch. The feed network employs a 180-degree rat-race hybrid coupler to realize a −3 dB power split, equal in magnitude, 180-degree difference in phase. Two branch-line couplers then divide the signal energy into two paths and give the signal to each of the output branches with the same amplitude, but phase-shifted by 90 degrees, wherein the relative phases at four feed points are 0, 90, 180, and 270 degrees. The final dimensions of the 2 × 2 element array are 112 × 97 × 0.8 mm3. The simulated result shows that the impedance bandwidth for a voltage standing wave ratio (VSWR) < 2 is around 39.86% (4.78–7.16 GHz), and the 3-dB simulated AR (axial ratio) bandwidth is about 24.2% (4.83–6.16 GHz), and the antenna has a peak gain of 7.69 dBi over the bandwidth.

Utilization of lime-dried sludge for eco-cement clinker production: effects of different feeding points.

Co-processing lime-dried sludge (LDS) in cement kilns is an appropriate technique to solve the problem of LDS disposal and promote the sustainable development for cement industry. However, there were limited studies that investigated the effects of feeding points on product quality and cement kiln emissions. In this study, simulated experiments were conducted by dividing the feeding points into high-temperature zones (HTZs) and raw mill (RM). Cement quality and major cement kiln emission characteristics were comprehensively investigated. The results showed that in terms of burnability, compressive strength and microstructure, the optimum co-processing amount of LDS were 9 wt% when feeding at RM, while 6% when feeding at HTZs. Meanwhile, the organic emissions of RM samples were mainly low environmental risk compounds of amides and nitrogenous heterocyclic compounds. Inorganic gaseous pollutions of NOX and SO2, respectively, were 8.11 mg/g DS and 12.89 mg/g DS, compared with 7.61 mg/g DS and 4.44 mg/g DS for HTZs. However, all the cement kiln emissions concentration were still much lower than standard requirements. Overall, RM had a bigger LDS co-processing capacity and higher, but acceptable, cement kiln emissions. Feeding LDS via RM could dispose larger amounts of sludge and provide more alternative materials for cement manufacturing.

Single-Layer Dual-/Tri-Band Inverted-F Antennas for Conformal Capsule Type of Applications

Additional resonances are often introduced in an inverted-F antenna (IFA) by modifying the “F” structure, which typically makes the antenna both complex and bulky. To mitigate this problem, novel dual-/tri-band conformal capsule antennas with simple configuration are proposed in this paper by modifying the ground of the IFA and shifting the feed point. With these modifications, the IFA is miniaturized, and yet it is able to simultaneously cover the MedRadio band (401–406 MHz) and ISM bands (902–928 MHz and/or 2.4–2.5 GHz). The resulting configurations remain simple and compact despite the modifications, which is very desirable for conformal capsule type of applications. Furthermore, the impedance matching characteristics of the proposed IFAs remain stable even when a battery is added inside the capsule and the size or the position of the battery is modified. Moreover, the impedance matching of the antenna continues to remain stable even as its surrounding environment is changed. The operating principle of the proposed dual-/tri-band IFAs is discussed in detail and parametric study is carried out to investigate the characteristics of the proposed antennas. The results of this paper are expected to be helpful for designing multiband antennas in the future.

The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target

Abstract. The Iceland Deep Drilling Project research well RN-15/IDDP-2 at Reykjanes, Iceland, reached its target of supercritical conditions at a depth of 4.5 km in January 2017. After only 6 days of heating, the measured bottom hole temperature was 426 °C, and the fluid pressure was 34 MPa. The southern tip of the Reykjanes peninsula is the landward extension of the Mid-Atlantic Ridge in Iceland. Reykjanes is unique among Icelandic geothermal systems in that it is recharged by seawater, which has a critical point of 406 °C at 29.8 MPa. The geologic setting and fluid characteristics at Reykjanes provide a geochemical analog that allows us to investigate the roots of a mid-ocean ridge submarine black smoker hydrothermal system. Drilling began with deepening an existing 2.5 km deep vertical production well (RN-15) to 3 km depth, followed by inclined drilling directed towards the main upflow zone of the system, for a total slant depth of 4659 m ( ∼ 4.5 km vertical depth). Total circulation losses of drilling fluid were encountered below 2.5 km, which could not be cured using lost circulation blocking materials or multiple cement jobs. Accordingly, drilling continued to the total depth without return of drill cuttings. Thirteen spot coring attempts were made below 3 km depth. Rocks in the cores are basalts and dolerites with alteration ranging from upper greenschist facies to amphibolite facies, suggesting that formation temperatures at depth exceed 450 °C. High-permeability circulation-fluid loss zones (feed points or feed zones) were detected at multiple depth levels below 3 km depth to bottom. The largest circulation losses (most permeable zones) occurred between the bottom of the casing and 3.4 km depth. Permeable zones encountered below 3.4 km accepted less than 5 % of the injected water. Currently, the project is attempting soft stimulation to increase deep permeability. While it is too early to speculate on the energy potential of this well and its economics, the IDDP-2 is a milestone in the development of geothermal resources and the study of hydrothermal systems. It is the first well that successfully encountered supercritical hydrothermal conditions, with potential high-power output, and in which on-going hydrothermal metamorphism at amphibolite facies conditions can be observed. The next step will be to carry out flow testing and fluid sampling to determine the chemical and thermodynamic properties of the formation fluids.

Application of compound Poisson process for modelling of ore flow in a belt conveyor system with cyclic loading

This paper deals with the analysis of the random process of cyclic loading of a mining belt conveyor with portions of ore discharged by loaders or trucks. Such transfer of transported ore from a cyclic to a continuous transport is typical for the specific mining operations implemented in the underground copper ore mines with room and pillar mining. The conveyors in such systems are usually significantly oversized in order to match the peak loads of cumulated discharges of ore hauled from mining fields by loaders. Therefore, the actual loadings that occur in the mining transportation systems need to be analysed to provide the data for more accurate design and control of belt conveyors. The large data-set of actual loadings of the belt conveyors has been used for the stochastic modelling of the analysed process. The compound Poisson process has been proposed as mathematical tool to analyse/describe properties of ore flow. The discussion of the chosen distribution functions and results of the fitted model simulations compared with the examined measurement data are presented. In this paper, the case of a belt conveyor loaded only by a single feeding point where loaders are randomly discharged have been analysed. More complex cases (several loading points, mixed ore supply from cyclic and continuous ore mass flow from preceding conveyors or ore bunkers) are under investigation and will be presented in the future.

Tool path optimisation method for large thin-wall part of spacecraft

Roughing tool path of panel machining, which is a bottleneck of spacecraft production, should be optimised rapidly to shorten process time. This problem has a large solution space, and surface quality should be taken into account. The decision variables are cavity machining order, feed point and cutting direction of each cavity. Our problem is presented as an asymmetric general travelling salesman problem (AGTSP). A cluster optimisation-based hybrid max–tmin ant system (CO-HMMAS) is proposed, which solves two sub-problems as a whole. The oriented pheromone and dynamic heuristic information calculating methods are designed. We analyse the differences between one-stage and two-stage AGTSP local search heuristics and combine CO-HMMAS with them properly. An improved Global 3-opt heuristic suitable for both symmetric and asymmetric cases is proposed with sharply reduced time complexity. Comparison experiments verified that, two-stage local search heuristics decrease solution error significantly and rapidly when the error is great, and one-stage ones improve a near-optimal solution costing much more computing time. Benchmarks tests show that, CO-HMMAS outperforms the state-of-the-art algorithm on several technical indexes. Experiments on typical panels reveal that all algorithm improvements are effective, and CO-HMMAS can obtain a better tool path than the best algorithm within less CPU time.

Foraging areas of streaked shearwater Calonectris leucomelas nesting on the Karamzin Island (Peter the Great Bay, East Sea)

Karamzin Island (the Peter the Great Bay, the East Sea) is the only nesting point of streaked shearwaters in Russian Federation. To understand and determine distribution patterns of streaked shearwaters along the Eastern Sea waters during nesting period, the Trackers WT-300 were set to 10 adult birds. Over the observation period (from 5 July 2016 to 7 January 2017), 4812 locations were registered. Analysis of data obtained revealed that main feeding points of colony studied were situated in the Peter the Great Bay along 50 m isobath and, to the less extension, near the eastern coast of Korean Peninsula. It was determined that streaked shearwaters most frequently visited waters with circular flows or zones of junctions of multidirectional flow. It was also shown that these zones had high concentrations of zooplankton.

Double-Side Electromagnetic Band Gap Structure for Improving Dual-Band MIMO Antenna Performance

A double-side EBG structure with equivalent circuit model is proposed in this paper. Making H shape on surface and H with bridge shape on ground, the novel EBG that is built on FR4 substrate with height of 1.6mm, gets compact size of 8.6x8.6 mm2 at 2.6 GHz resonant frequency. Using 1x7 EBG structures for dual-band MIMO system, several performance parameters of antenna are improved. Firstly, the mutual coupling between antenna elements gets -40dB in the lower band and -30dB in the higher one with narrow distance of 0.11l from feeding point to feeding point. Then, at 2.6GHz, the antenna gain is increased significant by 160% as well as radiation efficiency of antenna is better. This improvement is unable to get in previous EBG studies

A Handbag Zipper Antenna for the Applications of Body-Centric Wireless Communications and Internet of Things

The idea of making use of the metal zipper on the handbag to serve as an off-body antenna is proposed, and the simulations together with measurements have been carried out. The feeding point can be located at the bottom of the zipper, and to be more specific, around one of the teeth. The excitation at certain tooth of the zipper would bring variations in the reflection coefficients as well as the radiation patterns. No matter the zipper is totally closed, quarterly opened, half opened, or is even totally opened, the antenna can operate with acceptable performance, though the common status of the handbag zipper is closed. Thus, it is to some extent reconfigurable, especially for radiation patterns. A fractional bandwidth of 4.92% at 2.44 GHz of the industrial, scientific, and medical band with a gain of about 5 dBi has been achieved. The impact of the human body has been evaluated. It is noticeable but affordable. The measured results indicate reasonable agreements to that of the simulations in both the matching performance and the radiation feature for the zipper antenna, which seems to be a promising candidate for body-centric wireless communications and the Internet of Things.

Chemical looping combustion of hard coal and torrefied biomass in a 1 MWth pilot plant

Chemical looping combustion (CLC) is an emerging CO2 capture technology utilizing two interconnected circulating fluidized beds (CFB). An oxygen carrier is oxidized in the air reactor and reduced in the fuel reactor. In comparison to a classic oxyfuel process, no air separation unit is required to provide the oxygen needed to burn the fuel. The solid fuel, such as coal or biomass, is gasified in the fuel reactor, and the products from gasification are oxidized by the oxygen carrier. This work presents results of 110h autothermal and partial autothermal CLC operation with ilmenite and iron ore as oxygen carriers. Hard coal and a fuel blend of hard coal and torrefied biomass were used as fuels. The results show that the oxygen demand of the fuel reactor required for a complete conversion of unconverted gases was in the range of 27%. At the same time, the carbon capture efficiency was low in the present configuration of the 1 MWth pilot. This means that unconverted char left the fuel reactor and burned in the air reactor. The reason for this is that no carbon stripper unit was used during these investigations. Some possible modifications like an oxygen carrier with oxygen uncoupling, a lower fuel feeding point or a secondary fluidization of the fuel reactor could significantly enhance the carbon capture efficiency.

Low-Profile High-Power Optically Addressed Phased Array Antenna

A low-profile optically fed ultra-wideband-connected array (CA) antenna with increased operational power is presented. Introduction of a miniature optical prism into the fiber optic feed enables an efficient 90° coupling to a high-power charge-compensated-modified uni-travelling carrier photodiode connected directly at the feed point of an integrated CA antenna element. This technique significantly reduces the array profile and, herein, is implemented into a 1-D CA antenna array consisting of eight photodiode-coupled active dipole elements. The experimentally verified array achieves effective beamforming and beam steering over a 3-dB bandwidth of 6–17 GHz, as well as a peak effective isotropic radiated power of 27.5 dBm at 13 GHz.

Impedance Bandwidth Enhancement of a Novel Fabricated Fractal Patch Antenna Using Invasive Weed Optimization Algorithm

In this paper, the possibility of different configurations of a novel Koch fractal geometry for the miniaturization and broad banding of a microstrip patch antenna, while maintaining its gain and radiation pattern, is investigated. To achieve the best results, the invasive weed optimization (IWO) algorithm, which is shown to be very robust and adaptive, is used for optimization. The whole design procedure is auto-controlled by linking, the high-frequency structure simulator with MATLAB software. For the first configuration, IWO is used to find the best location of feed point to minimize the return loss, e.g., S 11 ( $$\left| {S_{11} } \right| < {-}10\;{\text{dB}}$$ ) and hence increasing the radiation efficiency of the proposed antenna. $$\left| {S_{11} } \right|$$ of about −40 dB was achieved. Next, the proposed fractal with air-filled substrate and a ring slit is presented. The key design parameters such as air gap height, the slot gap width, location of feed point have been optimized using IWO to obtain the best possible bandwidth. Simulation results show a fractional impedance bandwidth of about 40% (2.42–3.59 GHz). This band is used by weather radar and some communication satellites. Gain and radiation pattern of the proposed antenna are acceptable within the frequency bandwidth. A prototype of the antenna is also fabricated and tested. Measured parameters are in good agreement with the simulated results.

Experimental Study of the Delay Spread in an Indoor Radiating Cable System

This paper presents the signal time dispersion in an indoor radiating cable system by using wide-band propagation measurements. The indoor environment was a university building, and the measurements were carried out in the first, second and third levels using a vector network analyzer with a frequency range of 1.25–1.75 GHz. Two cases were studied. The results show that despite both cases having the same environment and installation, the different connections of the feeding point generate dissimilar conditions of the channel, e.g., the channel is most affected by signal delays in one case. The analysis of rms delay spread includes local and global distributions, spatial correlations, and scatter diagrams with the mean excess delay and path loss. Most of the time, the results indicate a higher concentration of power at the middle delay path, and the relationship between the rms delay spread and path loss depends mainly on the delay spread generated by the cable installation. It was found that the rms delay spread increases when the mobile antenna is near to the feeding point of the cable. Furthermore, little adjustments to the cable installation were also made and their effects on the channel are presented. Therefore, the radiating cable can provide an almost uniform coverage; however, the planning and installation of indoor radiating cable systems for high transmission rate must be carefully developed. These results allow us to understand the channel behavior for better planning and designing of radiating cable applications in indoor environments.

Wideband Filtering Balun on a Novel Hybrid Multimode Resonator With the Functionality of Vertical Transition

In this paper, a novel hybrid multimode resonator (MMR) is proposed and applied for design and exploration of a wideband filtering balun with the functionality of vertical transition. This hybrid MMR consists of two distinctive kinds of transmission lines: 1) microstrip line placed at the top and bottom layers, and 2) slotline formed on the middle common ground. With this combination, a hybrid MMR is constituted not only to realize two wideband filtering baluns, but also to achieve wideband vertical transition function. By virtue of the field conversion from the slotline to the output coupled $\lambda $ /2 microstrip line resonator, the 180 out-of-phase and equal magnitudes at the balun’s outputs can be achieved inherently over a wide frequency range. Meanwhile, multiresonant modes can be excited by properly setting a certain offset distance at the two feeding points in the hybrid MMR. As such, good signal transmission and wideband filter performances between the top-and bottom-layer microstrip lines can be gained over a desired wideband frequency range, and they can be determined by proper reallocation of these resonant modes. As examples, two prototype circuits are designed and fabricated to confirm the proposed concept. Furthermore, both simulated and measured results indicate that this proposed balun filter exhibits not only a high-selectivity filtering performance, but also good phase and magnitude imbalance performance in the wide operating band with the functionality of vertical transition.

Switchable non‐physical LTE/WWAN antenna

This research proposes a switchable non-physical LTE/WWAN antenna. It adopts the metal zone around the hinge slot, created by the existing display ground plane, keyboard ground plane, and metal hinges, to create the radiator. It then feeds a signal at the proper position in the hinge slot to effectively excite the resonance modes of the loop path around the hinge slot. Moreover, it adopts switchable feeding points to cover the LTE700/2300/2500 triple-bands required by LTE and the GSM850/900/1800/1900/UMTS penta-bands required by WWAN, respectively, and fulfils the operating requirements of fourth generation communication. In addition, since no additional deployment space and structure design for antenna is required, the design can resolve the space requirement for communication device, and provide new antenna design technology.

Dual Null Steering and Limited Beam Peak Steering Using Triple-Mode Circular Microstrip Patch Antenna

A compact triple-mode circular microstrip patch antenna capable of creating two nulls in the upper hemisphere and steering them independently is presented. The antenna consists of a central circular patch supporting TM11 mode, a TM21 mode shorted annular ring around it and another shorted annular ring supporting TM31 mode encompassing the other two radiators. Each mode is fed using two feed points to create right-handed circular polarization. Analytical and simulation studies show that by controlling the individual mode amplitude and phase ratios, radiation pattern can be reconfigured. Especially, two nulls can be generated in upper hemisphere and can be steered independently based on the ratio of applied excitation to each mode. This is a highly desirable feature for satellite receives antenna system with antijamming capability. To calculate the required modes excitation ratios, a MATLAB optimization code using a hybrid method of particle swarm optimization and pattern search was used. To apply the calculated excitation, an analog beamforming network consisting of digital variable gain attenuators, digital phase shifters, and low-noise amplifiers was used. This antenna was fabricated and tested for radiation patterns showing full hemispherical null steering along with limited beam peak steering.

Design and Development of Microstrip Patch Antenna

A Microstrip Patch Antenna is a type of radio antenna with a low profile, which can be mounted on a low surface. It is a narrow band, wide-beam fed antenna fabricated by etching the antenna element pattern in metal trace bonded to the dielectric Substrate such as a printed circuit board with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. The main aim of this work is to design, develop and test the Printed Circuit antenna (Microstrip Patch antenna) suitable for use in L-band frequency range of 1-2GHz. This study also emphasizes on simulation of micro-strip patch antenna using IE3D software to simulate & study the radiation pattern & other radiation pattern parameters and comparison with specifications/requirements. Co-axial Feed technique was adopted and the location of the feed point was varied within the radiating patch to arrive at the point of minimum return loss. This work is also focused on characterization of fabricated antenna in view of parameters like VSWR, Antenna efficiency, Axial ratio, Gain and radiation pattern.

Investigating alternative methods for enhancing the establishment of the zoophytophagous mirid Nesidiocoris tenuis (Reuter) in greenhouse tomato crops

The zoophytophagous mirid Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is an effective natural enemy of some major pests of tomatoes in the Mediterranean region. In this area the colonization of protected tomato crops by this biocontrol agent may be hampered by the application of measures aimed at avoiding the transmission to tomato plants of insect-vectored diseases (e.g. TYLCD). Furthermore, various factors, such as the scarce availability of preys on crop plants and the severe deleafing of tomato plants, may affect the population build-up of artificially introduced predatory mirids. Since these natural antagonists have become commercially available in Europe, several methods have been explored to enhance their establishment on greenhouse tomatoes. This work reports the results of experiments carried out to investigate the effects of different release methods on the establishment of N. tenuis in commercial greenhouse tomato crops grown in southern Sardinia (Italy). The techniques tested can be summarized as follows: a) release of mirids before transplanting; b) introduction into release points covered by non-woven films; c) introduction into uncovered feeding points; d) traditional release method. N. tenuis was introduced at a rate of 0.8 individuals per stem grown (2.4-3.2 mirids plant-1) in crops planted during late summer. All methods except the traditional one envisaged the distribution of 0.01 g plant-1 of Ephestia kuehniella Zeller eggs, supplied three times at two-week intervals, as an alternative food source. Two months after planting, pre-plant release and the introduction into covered or uncovered release points allowed the predatory mirid to reach significantly higher densities in comparison with the traditional release method. Under the conditions tested, the anticipation of release and the supply of an artificial food source appear to be decisive factors for enhancing the establishment of N. tenuis in greenhouse tomato crops.