Reconfigurable Pattern Research Articles

The ascending arousal system promotes optimal performance through mesoscale network integration in a visuospatial attentional task.

Previous research has shown that the autonomic nervous system provides essential constraints over ongoing cognitive function. However, there is currently a relative lack of direct empirical evidence for how this interaction manifests in the brain at the macroscale level. Here, we examine the role of ascending arousal and attentional load on large-scale network dynamics by combining pupillometry, functional MRI, and graph theoretical analysis to analyze data from a visual motion-tracking task with a parametric load manipulation. We found that attentional load effects were observable in measures of pupil diameter and in a set of brain regions that parametrically modulated their BOLD activity and mesoscale network-level integration. In addition, the regional patterns of network reconfiguration were correlated with the spatial distribution of the α2a adrenergic receptor. Our results further solidify the relationship between ascending noradrenergic activity, large-scale network integration, and cognitive task performance.

Optimization ofvirtually aperiodiclinear sparse arrays

AbstractMulti‐port multi‐mode antenna elements have the ability to move their phase centers and modify their radiation patterns electronically. Arrays composed of such elements are referred to as virtually aperiodic arrays in this paper. Herein, optimization of the mode excitation coefficients in virtually aperiodic sparse linear arrays is proposed, by introducing novel design constraints with the aim of synthesizing wide‐angle scanning, reconfigurable patterns, with grating/side lobe reduction. A dual‐mode patch antenna is used for demonstration purposes. An efficient convex optimization based algorithm is adopted to optimize the excitation weight at each element mode port, while considering the mutual coupling effects. Through full‐wave simulations, the effectiveness of the optimization in suppressing the unwanted radiation and adapting to different fields‐of‐view is shown. A novel investigation on the impacts of defining different mode excitation ratios on the radiation pattern characteristics is conducted.

A Pentaband Compound Reconfigurable Antenna for 5G and Multi-Standard Sub-6GHz Wireless Applications

This work proposes a low-profile, printed antenna that offers pattern and frequency reconfiguration functionalities printed on FR-4 substrate with a size of 46 × 32 × 1.6 mm3. The proposed antenna can operate in five different frequency bands, each one identified as a Mode, wherein there are possibilities of pattern reconfiguration. The frequency and pattern reconfigurability are made possible through 12 p-i-n diode switches (S1 to S12). The former is enabled through the switches S1 to S4 within the radiating patch, hence effectively controlling the resonant bands of the antenna; the latter is made possible through main lobe beam steering, enabled by the rest of the eight switches (S5 to S12), loaded in split parasitic elements designed on both sides of the radiator. The proposed antenna operates in the 5 GHz (4.52–5.39 GHz) band when all switches are OFF. When S1 is ON, the operating band shifts to 3.5 GHz (2.96–4.17 GHz); it changes to a 2.6 GHz (2.36–2.95 GHz) band when S1 and S2 are ON. When S3 is also turned ON, the antenna shifts to the 2.1 GHz Band (1.95–2.30 GHz). When S1–S4 are ON, the operating band shifts to a 1.8GHz (1.67–1.90 GHz) band. In all these bands, the return loss remains less than −10 dB while maintaining good impedance matching. At each operating band, the ON/OFF states of the eight p-i-n diode switches (S5 through S12) enable beam steering. The proposed antenna can direct the main beam in five distinct directions at 3.5GHz, 2.6 GHz, and 2.1 GHz bands, and three different directions at 5 GHz and 1.8 GHz bands. Different 5G bands (2.1, 2.6, 3.5, and 5) GHz, which fall in the sub 6GHz range, are supported by the proposed antenna. In addition, GSM (1.8 GHz), UMTS (2.1 GHz), 4G-LTE (2.1 GHz and 2.6 GHz), WiMAX (2.6 GHz and 3.5 GHz) and WLAN (5 GHz) applications are also supported by the proposed antenna, which is a candidate for handheld 5G/4G/3G devices.

Concentric circular compound reconfigurable microstrip patch antenna for wireless applications

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.

Investigation of functional brain network reconfiguration during exposure to naturalistic stimuli using graph-theoretical analysis

Objective. One of the most significant features of the human brain is that it can dynamically reconfigure itself to adapt to a changing environment. However, dynamic interaction characteristics of the brain networks in naturalistic scenes remain unclear. Approach. We used open-source functional magnetic resonance imaging (fMRI) data from 15 participants who underwent fMRI scans while watching an audio–visual movie ‘Forrest Gump’. The community detection algorithm based on inter-subject functional correlation was used to study the time-varying functional networks only induced by the movie stimuli. The whole brain reconfiguration patterns were quantified by the temporal co-occurrence matrix that describes the probability of two brain regions engage in the same community (or putative functional module) across time and the time-varying brain modularity. Four graph metrics of integration, recruitment, spatio-temporal diversity and within-community normalised centrality were further calculated to summarise the brain network dynamic roles and hub features in their spatio-temporal topology. Main results. Our results suggest that the networks that were involved in attention and audio–visual information processing, such as the visual network, auditory network, and dorsal attention network, were considered to play a role of ‘stable loners’. By contrast, ‘unstable loner’ networks such as the default mode network (DMN) and fronto-parietal network tended to interact more flexibly with the other networks. In addition, global brain network showed significant fluctuations in modularity. The ‘stable loner’ networks always maintained high functional connectivity (FC) strength while ‘unstable loner’ networks, especially the DMN, exhibited high intra- and inter-network FC only during a low modularity period. Finally, changes in brain modularity were significantly associated with variations in emotions induced by the movie. Significance. Our findings provide new insight for understanding the dynamic interaction characteristics of functional brain networks during naturalistic stimuli.

Using Antenna Arrays with Only One Active Element for Beam Reconfiguration and Sensitive Study in Dielectric Media.

Antenna array pattern reconfiguration is usually achieved by changing the relative amplitudes and/or phases of the excitation distribution present in the array, at the cost of complex feeding networks. In this work, the mechanical displacement of a parasitic array perpendicular to another array with a single driven element is proposed. Additionally, the antenna is optimized addressing the variation of its response led by changes of the environmental dielectric constant of a surrounding gaseous medium. In such a way, a novel multipurpose antenna of utmost simplicity is obtained. From the computation of the self and mutual impedances, a control of the antenna radiation pattern by means of the induced currents in the parasitic elements is modelled. To illustrate the procedure, the technique will be applied to the variation of the side lobe level of a pencil beam and to obtain a flat-topped broadside beam from the same pencil beam, something with high interest for satellite applications. The proposed methodology represents an advance on the development of multipurpose antennas which resounds in simplicity not only in the reconfiguration of antenna beams, but in applications for the detection of particulate matter and/or measurements of the atmospheric dielectric constant.

P-054. Maternal hemodynamics assessed by USCOM® device in patients with hypertensive disorders of pregnancy during peripartum

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.

P-067. Biomarkers profiles of hypertensive disorders of pregnancy on term gestational period: revival of von Willebrand factor

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.

Noniridescent structural color from enhanced electromagnetic resonances of particle aggregations and its applications for reconfigurable patterns

Hypothesis: The conventional noniridescent structural colors refer to the coherent scattering of visible light by the short-range ordered structures assembled from the small colloids (100–250 nm). Our hypothesis is that noniridescent structural color can be generated by the random aggregations of large silica particles through the enhanced electromagnetic resonances.Experiments: The random aggregations of large silica particles (350–475 nm) were prepared through the infiltration of silica particles solution with the porous substrate. The mechanism of the structural color is investigated. Reconfigurable patterns are prepared.Findings: Dissimilar to the conventional noniridescent colors, the angle-independent colors of silica aggregations originate from the enhanced electromagnetic resonances due to the random aggregation of the particles. The colors (blue, green, and red) and corresponding reflection peak positions of the particle aggregations can be well controlled by simply altering the size of the silica particles. Compared to the traditional prints with permanent patterns, reconfigurable patterns with large-area and multicolor can be fabricated by the repeatedly selective spray of water on the substrate pre-coated with noniridescent colors. This work provides new insight and greenway for the fabrication of noniridescent structural colors and reconfigurable patterns, and will promote their applications in soft display, green printing, and anti-counterfeiting.

Design of Reconfigurable Antenna for RFID System

This paper proposes a reconfigurable antenna for RFID system which can operate between 860MHz to 960MHz frequency that belongs to ultra-high frequency (UHF) band used in Malaysia with the center frequency of 910MHz. One rectangular slot and two triangle-shaped slots are used in designing this antenna. A good circular polarization obtained from the slotted structure along the diagonal axis in the design. RF pin diodes are used as the switching mechanism of the antenna. However, in this work to proof the concept of switching mechanism, copper pins are used as artificial switches. Parasitic elements are deployed on the right and left side of the driven element to assist the radiation pattern reconfiguration. Overall, the proposed antenna able to steer the beam at approximately at -30°, -16°, and 10° with peak gain of 3.2dB and average gain of 2.5dB. With this result, overall coverage of UHF RFID reader antenna could be improved.

Erratum to “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OAM” [Feb 21 1168-1172

In <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , the title of the article was incorrectly stated as “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OA. ” The correct title is: “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OAM. ”

Advanced SuDoKu-Based Reconfiguration Strategies for Maximum Power Extraction From Partially Shaded Solar Photovoltaic Array

Abstract Individual performance of photovoltaic (PV) modules is contravened by mismatch losses which result in blockage in most of the solar power generated by the PV array (PVA). Partial shading conditions (PSCs) are the main causes of these losses. Several techniques have been discussed to reduce the issues caused by PSCs. Reconfiguration techniques have been proven to be one of the most successful methods that help toward this cause. In this method, the location of PV module (PVM) in the PVA is reconfigured so that the shading effects get distributed throughout the entire array and, hence, maximizing the power output. Two novel reconfiguration patterns such as canonical SuDoKu (CS) and multi diagonal SuDoKu (MDS) for total cross tied (TCT) configuration have been put forth in this paper. This approach aims to rearrange the PVMs in the TCT array as per the fed-in patterns without causing a change in the internal electrical connections. Further parts of the paper focus on the comparison of the proposed pattern's performance with other pre-existing PVA arrangements such as, TCT, SuDoKu, optimal SuDoKu (OS), and modified SuDoku (MS) by taking into account the effects of global maximum power (GMP) point, mismatch power loss, fill factor, and performance ratio. The results obtained from the detailed analysis presented in this paper give proper evidence that, in many cases, the GMP is amplified in the CS and, in all cases, GMP is amplified in the proposed MDS PVA under different shading conditions.

Differentially-fed dual-polarization four beam pattern reconfigurable antenna

A planar differentially-fed dual-polarization four beam pattern reconfigurable antenna is proposed in this paper. It is composed of two orthogonal dual-dipole elements and four parasitic elements embedded with four PIN diodes. The two dual-dipole elements are overlapped and 90° rotational symmetrical, making the overall structure very compact. Dual-dipole elements are excited differentially through short microstrip feeding lines. All dipoles and parasitic elements are etched on the same substrate, resulting in a full planar structure. Four beam pattern reconfigurability and dual-polarization reconfigurability are realized by switching the combinations of PIN diodes states. The antenna obtains a −10 dB impedance bandwidth of 8.9% covering from 3.27 to 3.58 GHz, an average gain of 5.6 dBi, an FBR about 10 dB, and average radiation efficiency of 68% in the measurement. The proposed antenna has compact structure, low cost and easy processing.

Large-scale network topology reveals brain functional abnormality in Chinese dyslexic children

It has been revealed that dyslexic children learning alphabetic languages are characterized by aberrant topological organization of brain networks. However, little is known about the functional organization and the reconfiguration pattern of brain networks in Chinese dyslexic children. Using graph theoretical analysis and functional magnetic resonance images (fMRI), we examined this issue specifically from the perspective of functional integration and segregation. We first compared large-scale topological organizations between dyslexic children and typically developing children during a Chinese phonological rhyming task, and found that dyslexic children showed increased local efficiency and clustering coefficient compared with typically developing children, which were negatively correlated with task performance. Furthermore, dyslexic children and typically developing children could be accurately distinguished at the individual-subject level based on the nodal local efficiency or clustering coefficient. Second, we studied the group difference of network reconfiguration and found that dyslexic children showed more difficulty when shifting from the resting state to the phonological task. Our results suggest an over-segregated brain functional organization and deficits in brain network reconfiguration in Chinese dyslexic children, which helps to advance our knowledge on the neural mechanisms underlying dyslexia.

An Event-B formal model for a system reconfiguration pattern and its instantiation: application to Web services compensation

An Event-B formal model for a system reconfiguration pattern and its instantiation: application to Web services compensation

Switched-Beam Graphene Plasmonic Nanoantenna in the Terahertz Wave Region

Large-distance communications beyond a few meters is challenging for Terahertz (THz) signals because of high spreading loss and absorption in the media. The smart antenna concept used for RF antennas to improve the signal-to-interference/noise level can be extended to these THz antennas. Out of the two types of implementations of this concept, viz. (i) adaptive array and (ii) switched-beam antenna, this paper presents the switched-beam nanoantenna for the THz wave region. Based on the Yagi-Uda antenna concept, switched-beam graphene nanoantennas over silicon dioxide (SiO2) substrate is proposed in this paper. In one case (Antenna-I), the antenna is able to switch the beam in ± 90o directions, whereas in the other case (Antenna-II), the switching directions are 0o, ± 90o, 180o. This pattern reconfigurability can also be observed over a frequency range leading to simultaneous pattern and frequency reconfigurable nature of the nanoantenna. The reconfigurability is obtained by changing the graphene conductivity through its chemical potential. Due to plasmonic wave propagation in graphene at THz, the proposed graphene nanoantenna resonates at a sub-wavelength scale. Design aspects and the working principle of switched-beam graphene plasmonic nanoantennas in the THz region are discussed in this paper.

A Conformal, Dynamic Pattern-Reconfigurable Antenna Using Conductive Textile-Polymer Composite

A conformal antenna with electronically tuning capability of its radiation pattern between broadside and monopole-like patterns is proposed. The antenna is based on a proximity-fed circular patch, loaded with a ring patch and four rectangular slots. The design is planar without any use of rigid shorting posts or a complex feeding network. The reconfigurability is achieved by activating and deactivating the slots using p-i-n diodes to switch between TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> (monopole-like mode) and perturbed TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> distributions (broadside mode) of the antenna. For conformability, the antenna is fabricated using a highly flexible PDMS-conductive fabric composite. All the antenna parts, including the RF switches, wires, and dc biasing circuit, are fully encapsulated by PDMS to provide resilience against deformation and harsh environment. Investigations on the RF performance and mechanical stability of the antenna were conducted. Under various bendings, it was demonstrated that all the antenna components, including those for electronic switching, remained intact and in working order even under the radius bending of 40 mm, thus maintaining good pattern reconfigurability and overall performance. When bent, the measured results at 5.2 GHz show a stable radiation performance relative to those of the flat case (i.e., the maximum gain of 2.9 dBi and the efficiency of 64% in the broadside mode, corresponding to 1.75 dBi and 52% in the monopole-like mode). To the best of our knowledge, all these features have never been demonstrated in previously published pattern reconfigurable antennas.

Digital pattern synthesis with a compact MIMO antenna of half-wavelength diameter

The paper presents a compact multiport antenna, with beamforming capabilities and a realized gain of 4.31 dBi with the size of λ/2. The antenna allows digital beamforming with independent control over three parameters: main-beam direction, beamwidth, and null-depth. Those parameters can be dynamically adjusted within a continuous range, create multiple beams for different frequency channels, and simultaneously generate multiple digital patterns. Due to digital beamforming capabilities, the proposed antenna offers much greater flexibility over switch-based analogue beamforming of Electronically Steerable Parasitic Array Radiator (ESPAR) antennas. The reconfiguration properties are achieved by using superposition of three dipole-like radiation patterns, where each radiator generates different spherical mode, i.e. with different angular phase distribution in the horizontal plane. This allows beamsteering with compact size, while the use of different modes ensures low Envelope Correlation Coefficient (ECC) from 10−4 to 3.2 × 10−5 for the operating frequency of 2.4 GHz. The proposed technique allows for significantly greater pattern reconfiguration than any reconfigurable antenna or array of comparable size and is a perfect candidate for Software Defined Radios.

ADMM-based array antenna synthesis algorithm with reconfigurable pattern element selection

The paper considers the array beam pattern synthesis (BPS) problem with reconfigurable pattern elements (RPE). Both the array weight and the array pattern are optimized, which further suppresses the peak sidelobe level (PSLL) compared with the fixed pattern array. For the array pattern optimization, the conventional selecting of appropriate N elements from K radiation patterns requires to evaluate all possible KN choices, resulting in the non-deterministic polynomial-hard RPE selection problem. In this work, this problem is solved through investigating different element pattern combinations with randomly arranged pattern locations. In such way, the possible solutions to the RPE selection problem has an overall choices of CN+K−1K−1=(N+K−1)!N!(K−1)!, which extremely shrinks the solution space. An algorithm with the RPE selection and array weight optimization is proposed for the BPS problem. Furthermore, the alterative direction method of multipliers (ADMM) framework is introduced to accelerate the computation speed. The proposed algorithm provides an effective scheme for generating appropriate RPE combinations for PSLL suppression, resulting in a wider-angular scanning ability for array antenna. Simulation results demonstrate 0 dB to 4 dB lower PSLL can be obtained compared with the algorithms based on the fixed element pattern.

A Flexible and Pattern Reconfigurable Antenna with Small Dimensions and Simple Layout for Wireless Communication Systems Operating over 1.65–2.51 GHz

This research article proposes a compact frequency and pattern reconfigurable flexible antenna for heterogeneous applications. A triangular monopole antenna with a semicircular stub is made frequency and pattern tunable by connecting and disconnecting two inverted L-shaped stubs utilizing diodes. When either of the stubs is connected to the radiator, a relative phase difference happens at both ends of the radiator that changes the direction of the electromagnetic radiations, consequently pattern reconfigurability can be obtain. Besides that, because of the reactive load introduced by the stubs, the antenna’s effective length has changed and, as a result, the frequency reconfigurability can be attained. The antenna features a compact size of 40 × 50 × 0.254 mm3 corresponding to 0.22λo × 0.27λo × 0.001λo, where λo is free-space wavelength at 1.65 GHz, while its operational bandwidth is from 1.65 GHz to 2.51 GHz, with an average gain and radiation efficiency of better than 2.2 dBi and 80%, exhibiting a pattern reconfigurability of 180° in the E-plane. The frequency of the proposed antenna can be switched from 2.1 GHz to 1.8 GHz by switching the state of both diodes in OFF and ON-state, respectively. The fabricated prototype of the antenna is tested to verify its performance parameters. In addition, to validate the proposed design, it has been compared with prior arts in terms of the overall size, reconfigurability type, flexibility, radio frequency (RF) switch type used for reconfigurability, and frequency bandwidth. The proposed antenna provides smaller size with a large bandwidth coverage alongside with discrete RF switch type with the advantages of flexibility and both frequency and pattern reconfigurability. As a result, the proposed compact flexible and pattern reconfigurable antenna is a promising candidate for heterogeneous applications, including the global system for mobile (GSM) band (1800 and 1900 MHz) and industrial, scientific and medical (ISM) band (2.4 GHz) along with well-known cellular communication bands of 3G, 4G, and long term evolution (LTE) bands ranging from 1700–2300 MHz around the globe.